Dissertations / Theses: 'Malic acid'

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Mitsch, Michael James. "Characterization of the NADP+-dependent malic enzyme of Sinorhizobium (Rhizobium) meliloti and investigations into the requirements of malate uptake and malic enzyme activity in bacteroids /." *McMaster only, 2001.

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Pounder, Ryan J. "The synthesis and ring-opening polymerisation of novel cyclic esters from malic acid." Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/34607/.

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The work in this thesis is directed towards the preparation of cyclic ester monomers using malic acid as a renewable resource. Their subsequent controlled ring-opening polymerisation (ROP) to yield functionalised poly(ester)s is studied and application in micellar self-assembly reported. Chapter 1 reviews the many synthetic strategies that have been employed in the preparation of functional glycolides, lactides, ε-caprolactones, δ-valerolactones and β-propiolactones. Their subsequent polymerisation and applications are also discussed. Chapter 2 describes the improved synthesis of 3-(S)- [(benzyloxycarbonyl)methyl]- and 3,6-(S)-[di(benzyloxycarbonyl)methyl]-1,4- dioxane-2,5-diones, BMD and malide respectively, from L-malic acid. Controlled organocatalytic ROP of BMD realised functional poly(glycolic acid-co-benzyl α- malate)s (PBMD) with the choice of initiator proving important in determining the resulting molecular weight. Successful hydrogenolysis of these poly(glycolic acid-co-benzyl α-malate)s yielded hydrophilic poly(glycolic acid-co-α-malic acid)s (PGMA) with subsequent degradation studies in H2O observing complete degradation after six days. In Chapter 3, the synthesis of 5-(S)- and 5-(R)-[(benzyloxycarbonyl)methyl]-1,3- dioxolane-2,4-dione (L-malOCA and D-malOCA respectively) from L- and Dmalic acid respectively is reported. ROP of malOCA with a range of pyridine based catalysts enabled the synthesis of functional poly(benzyl α-malate)s (PBMA). Mechanistic studies revealed the formation of several side products that were eliminated via judicious choice of catalyst and column chromatography. Subsequent hydrogenolysis realised hydrophilic poly(α-malic acid)s (PMA) with degradation studies in H2O observing complete degradation after 10 days. Chapter 4 reports the synthesis of novel amphiphilic PEO-b-PBMA block copolymers by the ROP of L-malOCA or D-malOCA from PEO macroinitiators with subsequent self-assembly realising polymeric micelles. Variation in both size dimensions and stability of the micelles through changes in both the hydrophobic and hydrophilic block lengths and their relative ratios was demonstrated. The self-assembly of an equimolar mixture of homochiral PEO-b- P(L-BMA) and PEO-b-P(D-BMA) resulted in the formation of stereocomplexed polymeric micelles. Chapter 5 provides a summary of the findings in chapters 2 – 4 with chapter 6 providing the corresponding experimental data.

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Hahn, Christian Joachim [Verfasser]. "Polyesters Based on Malic Acid - Pendant Hydroxyl Groups as Distinctive Feature for Versatile Modifications / Christian Joachim Hahn." Aachen : Shaker, 2013. http://d-nb.info/1051574692/34.

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Sandéhn, Alexandra. "Capillary Organic Electronic Ion Pump for Delivering Malic Acid - Towards Better Understanding of Drought Tolerance in Tropical Plants." Thesis, Linköpings universitet, Laboratoriet för organisk elektronik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-178191.

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Delivery of biologically relevant ions such as drugs, neurotransmitters and hormones have been recognized as powerful a tool to control physiology of animals and plants for research purposes and practical applications. In the plant research community, ions are most commonly delivered as part of a solvent by soaking, spraying, pipetting or by adding to the soil. These methods have low control of the delivery dynamics and quantity of ion uptake. These issues motivated the development of the Organic Electronic Ion Pump (OEIP), which delivers only ions of interest by applying an external electric field through a polyelectrolyte membrane of high fixed charge concentration. A miniaturized, implantable version of the OEIP based on capillary fibres (c-OEIP), where the polyelectrolyte is enclosed in a capillary, enabled even higher precision of the delivery. In this master thesis, c-OEIP has been applied in the tropical plant Kalanchoe Blossfeldiana, chosen due to its characteristic skill to gradually learn to save water: while maturing it shifts to night time photosynthesis and transpiration, called Constitutive Crassulacean Acid Metabolism. A better understanding of this metabolism and water saving ability could guide engineering of enhanced drought tolerance in crop plants, which is motivated by the increasing global warming. One of the biologically relevant ions that is potentially involved in this water-saving learning process is the malate ions. The aim of this thesis is to test the hypothesis that c-OEIP is able to deliver malate ions to cause a reduction in stomatal conductance and transpiration of intact leaves of Kalanchoe Blossfeldiana. To test this hypothesis, firstly, the capillary-based OEIP were fabricated using polyimide coated glass capillaries filled with AETMAC polyelectrolyte. The ability of these devices to deliver malic acid (MA) was verified by using current-voltage characterisation during loading and delivery of MA. Secondly, the setup for MA delivery with c-OEIP to intact kalanchoe leaf was developed, optimising the insertion method to minimize the wounding of the plant and increase assay reproducibility. Finally, the MA was delivered to intact kalanchoe leaves via c-OEIP, where the plant transpiration response was evaluated using standard gas exchange porometer and also novel infrared camera, as plant temperature can be correlated with plant transpiration status. The results indicate that c-OEIP can deliver MA and trigger reduction of transpiration of young kalanchoe leaves, supporting the hypothesis that malate ions act to reduce stomatal conductance, potentially conveying a feedback message from the mesophyll to the guard cells.

Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet

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Coetzee, Zelmari. "Site and vintage response of malic and tartaric acid in Vitis vinifera L. cv’s Cabernet Sauvignon and Sauvignon blanc." Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85736.

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Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Acids are one of the major components that originate largely from the berry, that are found in wine, and that influence the sensory perception. The presence of organic acids in adequate concentrations in the grape berry, of which tartaric- and malic acid are the main organic acids present, is important as this determines the potential of a must to produce a good and stable wine. The effect of temperature on the organic acid content of the must is widely discussed with higher temperatures in general being associated with lower quantities of organic acids present in the juice, and lower temperatures during ripening associated with higher quantities, specifically in the case of malic acid. Due to the topographical diversity of the Stellenbosch Wine of Origin district and the closeness of the ocean and the occurrence of sea breezes, the mesoclimate differs greatly over short distances. Sixteen sites, consisting of eight Sauvignon Blanc and Cabernet Sauvignon sites respectively, were selected from a broader terroir study site network. Three vintages with complete climatic datasets were selected for vintage comparisons. Climate in the study area was monitored on differing scales, and data from a weather station network, as well as from mesoclimatic dataloggers within the sites were available. The available data was firstly compared to determine the variability of the data, not only between the two climatic scales, but also between the sites. Different climate classification indices and parameters available in literature were thereafter compared and evaluated for the best representation in this area. The Huglin index was found to be a better representation regarding the thermal climatic indices. Due to the great differences between temperatures noted for the mesoclimatic loggers and the nearest automatic weather station, the use of mesoclimatic logger data was preferred, and is advised in future studies where this scale of data is available. Malic and tartaric acid has a definite synthesis period up until véraison, after which the content of tartaric acid remains constant in the berry and the content of malic acid decreases until harvest due to mainly respiration. The temperature data was therefore separated in a synthesis period from flowering to véraison, and a ripening period from véraison to harvest. In this study, clear differences were firstly seen in the climate as expected, not only between sites per vintage, but in addition between vintages and between vintages per site. The phenological differences between the sites could be largely attributed to the differences in temperature as phenology and temperature was found to be highly correlated in this study. Differences in the ripening parameters were noticed in addition to the contents of the organic acids between sites, although no definite contribution of temperature was shown to affect the contents of these compounds at either véraison or harvest. These differences may be attributed to other factors such as the soil water content and the canopy architecture. In addition, these factors all contribute in differing percentages to the differences found in the contents per site. It was found though that temperature can be used as an indicator of the organic acid content in the grape berry, considering that the temperature data is available on a mesoclimatic scale, separated in a synthesis and period of degradation, and the number of hours within the temperature thresholds are determined. Differences seen in the organic acid contents can however not only be attributed to the differences in topography and the temperature as discussed in this study.
AFRIKAANSE OPSOMMING: Sure is belangrike druifkomponente wat grootliks hul oorsprong in die korrel het, in die wyn voorkom, en die sensoriese persepsie van die wyn beïnvloed. Die voorkoms van organiese sure in genoegsame konsentrasies in die korrel, waarvan wynsteensuur en appelsuur die hoof organiese sure is, is belangrik aangesien dit die potensiaal van die sap om ŉ goeie en stabiele wyn te produseer, bepaal. Hoe temperatuur die inhoud van organiese sure in die druiwesap affekteer is gereeld onder bespreking, met hoër temperature in die algemeen geassosieer met ŉ laer inhoud van organiese sure, terwyl laer temperature geassosieer word met ŉ hoër inhoud van organiese sure in die sap, veral in die geval van appelsuur. As gevolg van die topografiese diversiteit van die Stellenbosch Wyn van Oorsprong distrik, asook die nabyheid van die oseaan met die gepaardgaande voorkoms van die seebries, verander die mesoklimaat aansienlik oor klein afstande in hierdie area. Vir die studie was sestien wingerde, wat bestaan het uit agt Sauvignon Blanc en agt Cabernet Sauvignon wingerde, geselekteer vanuit ŉ groter terroir studie. Verder was drie seisoene, met volledige klimaatsdatastelle, geselekteer vir die vergelyking van data tussen die seisoene. Klimaat was op verskillende skale binne die studie area gemonitor en data van ŉ weerstasie netwerk, sowel as van mesoklimaat dataversamelaars binne die wingerde, was beskikbaar. Die beskikbare datastelle was vergelyk, asook geëvalueer, om die mees verteenwoordigende datastel vir die area te bepaal. Met die oorweging van die termiese indekse was daar gevind dat die Huglin indeks beter verteenwoordigend van die area was. Verder, as gevolg van die groot verskille wat gevind is tussen die temperature gemeet met die mesoklimaat dataversamelaars en die naaste outomatiese weerstasie, was daar besluit dat die gebruik van die mesoklimaat data verkies is en is dit ook aan te beveel vir die gebruik in toekomstige navorsing indien die tipe data beskikbaar is. Wynsteen- en appelsuur het beide ŉ definitiewe sintese periode tot en met véraison, waarna die hoeveelheid wynsteensuur in die korrel relatief konstant bly en die hoeveelheid appelsuur afneem hoofsaaklik as gevolg van respirasie. Die temperatuur data was dus verdeel in ‘n periode van sintese vanaf blom tot en met véraison, en ŉ rypwordingsperiode vanaf véraison tot en met oes. In hierdie studie was daar eerstens groot verskille waargeneem in die klimaat soos wat daar verwag is. Hierdie verskille was nie net waargeneem as tussen die seisoene nie, maar ook tussen die wingerde binne ŉ seisoen. Die fenologiese veskille tussen die wingerde wat ook waargeneem is, kon hoofsaaklik aan die verskille in die temperatuur toegeskryf word en ŉ goeie korrelasie tussen temperatuur en fenologie is opgemerk. Merkwaardige verskille in die rypwordingsparameters, asook in die inhoud van die organiese sure, was waargeneem, alhoewel die bydrae van temperatuur op die inhoud van hierdie komponente by véraison of oes nie as definitief getoon is nie. Dit kan toegeskryf word aan die bydrae van ander faktore, soos byvoorbeeld die grondwaterinhoud en die lowerargitektuur, op die inhoud van hierdie komponente. Die addisionele faktore dra egter in verskillende persentasies by tot die verskille waargeneem tussen die wingerde.

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Horáček, Pavel. "Studium produkce extracelulárních polymerů pomocí mikroorganismu Aureobasidium pullulans." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2013. http://www.nusl.cz/ntk/nusl-216967.

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The diploma thesis is focused on the study of the influence of cultivation conditions and arrangement for the production of extracellular polymeric substances by using yeast-like microorganism Aureobasidium pullulans. In the theoretical part a brief description of A. pullulans, its use in biotechnology and produced exobiopolymers, especially pullulan and poly-L-malic acid are presented. The first aim of the experimental part was to set the most appropriate cultivation conditions for A. pullulans CCM 8182. Growth and production properties in optimum conditions were compared with cultivation on waste substrates - oat bran, buckwheat husks, apple fiber and others. Waste substrates can be used as cheap nutrient sources which enable reducing cost of potential biotechnological production. As a further part of this work, optimization of HPLC/RI method for analysis of exobiopolymers has been done. Optimal mobile phase composition and chromatography conditions were proposed. Column Roa organic acid H+ was the most suitable for simultaneous separartion of glucose and malic acid. Before HPLC analysis hydrolysis of polymers was done. Sulphuric acid (5 mmol/L) was used as a mobile phase at flow rate 0.5 mL/min and temperature 60 °C. The highest production of pullulan occurred using oat bran as a substarate (13.03 g/L) at an initial pH 7.5. Maximum production of poly-L-malic acid was observed during the cultivation on apple peels (2.89 g/L) at pH 6. It was found that the higher production of poly-L-malic acid occurred at pH 6, while higher production of pullulan was at pH 7.5.

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Al-Hossain, Md Shahriar. "Study of superconducting and electromagnetic properties of un-doped and organic compound doped MgB₂ conductors." Access electronically, 2008. http://ro.uow.edu.au/theses/90.

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Kniel, Kalmia Elisabeth. "Evaluation of chemical treatments and ozone on the viability of Cryptosporidium parvum oocysts in fruit juices." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/27243.

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Cryptosporidium parvum is a protozoan parasite historically associated with waterborne and more recently foodborne outbreaks of diarrheal illness. Contamination of certain foods, such as unpasteurized apple cider, with infective oocysts may occur as oocysts are shed in the feces of common ruminants like cattle and deer that graze in and around orchards. Cryptosporidiosis can result in a severe illness for previously healthy individuals and a life-threatening illness in immunocompromised individuals. Disease occurs after the ingestion of small infective oocysts (4 to 5 mm in size). The relatively thick membrane of the oocysts allows them to be resistant to chlorine and many other environmental pressures, making oocysts difficult to inactivate. In this study, alternative treatments to pasteurization were evaluated for their ability to inhibit C. parvum oocyst viability in fruit juices. Oocyst viability was analyzed with a cell culture infectivity assay, using a human illeocecal cell line (HCT-8) that is most similar to human infection. The percent inhibition of infection by each treatment was determined along with the corresponding log reduction for the treatments found to be most effective. Infection by treated oocysts was compared to that of control untreated oocysts. Cell monolayers were infected with 10⁶ treated oocysts or a series of 10-fold dilutions. Parasitic life stages were visualized using an immunohistochemistry system and 100 microscope fields counted per monolayer. Organic acids and H₂O₂ were added on a wt/vol basis to apple cider, orange juice, and grape juices. Malic, citric, and tartaric acids at concentrations from 1%-5% inhibited C. parvum infectivity of HCT-8 cells by up to 88%. Concentrations ranging from 0.025%-3% H₂O₂ were evaluated where addition of 0.025% H₂O₂ to each juice resulted in a >5 log reduction of C. parvum infectivity as determined with an MPN-based cell culture infectivity assay. Treating apple cider, orange juice, and grape juice with ozone for a time period of 30 seconds up to 15 minutes at 6Â° and 22Â°C (0.9 g/L flow rate) inhibited C. parvum viability to > 90% as monitored in the cell culture assay. It is hypothesized that oocyst wall proteins that are necessary for infection are oxidized by the reactive oxygen species generated from the decomposition of the ozone and hydrogen peroxide treatments. These treatments or combinations thereof may offer potential alternatives to traditional pasteurization for fruit juices to successfully inhibit C. parvum viability.
Ph. D.

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Volschenk, Heinrich. "Characterisation of L-malic acid metabolism in strains of Saccharomyces and the development of a commercial wine yeast strain with an efficient malo-ethanolic pathway." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/52728.

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Dissertation (PhD)--University of Stellenbosch, 2002.
ENGLISH ABSTRACT: L-Malic and tartaric acid are the most prominent organic acids in wine and playa crucial role in winemaking processes and wine quality, including the organoleptic quality and the physical, biochemical and microbial stability of wine. The production of premium wines depends on the oenologist's skill to accurately adjust wine acidity to obtain the optimum balance with other wine components to produce wine with optimum colour and flavour. Strains of Saccharomyces, in general, rarely degrade L-malic acid completely in grape must during alcoholic fermentation, with relatively minor modifications in total acidity during vinification. The degree of L-malic acid degradation, however, varies from strain to strain. Some strains of Saccharomyces are known to be able to degrade a higher percentage of L-malic acid, but the underlying reason for this phenomenon is unknown. The underlying mechanisms of this phenomenon have been partially revealed during preliminary transcriptional regulation research during this study. In contrast, S. pombe cells can effectively degrade up to 29 gil L-malic acid via the malo-ethanolic pathway that converts L-malic acid to pyruvate and CO2, and ultimately to ethanol under fermentative conditions. A number of reasons for the weak degradation of L-malic acid in Saccharomyces cerevisiae have been postulated. Firstly, S. cerevisiae lacks the machinery for the active transport of L-malic acid found in S. pombe and relies on rate-limiting simple diffusion for the uptake of extracellular L-malic acid. Secondly, the malic enzyme of S. cerevisiae has a significantly lower substrate affinity for L-malic acid (Km = 50 mM) than that of S. pombe (Km = 3.2 mM), which contributes to the weaker degradation of L-malic acid in S. cerevisiae. Lastly, the mitochondrial location of the malic enzyme of S. cerevisiae, in contrast to the cytosolic S. pombe malic enzyme, suggests that the S. cerevisiae malic enzyme is inherently subject to the regulatory effects of fermentative metabolism. The malate permease gene tmael) and the malic enzyme gene (mae2) of S. pombe was therefore cloned and co-expressed in single or multi-copy under regulation of the constitutive S. cerevisiae 3-phosphoglycerate kinase (PGK1) promoter and terminator sequences in a laboratory strain of S. cerevisiae. This introduced a strong malo-ethanolic phenotype in S. cerevisiae where L-malic acid was rapidly and efficiently degraded in synthetic and Chardonnay grape must with the concurrent production of higher levels of ethanol. Functional expression of the malo-ethanolic pathway genes of S. pombe in a laboratory strain of S. cerevisiae paved the way for the genetic modification of industrial wine yeast strains of Saccharomyces for commercial winemaking. A prerequisite for becoming an inherited component of yeast is the stable integration of the malo-ethanolic genes into the genome of industrial wine yeast strains. Genetic engineering of wine yeasts strains of Saccharomyces is, however, complicated by the homothallic, multiple ploidy and prototrophic nature of industrial strains of Saccharomyces. Transformation and integration of heterologous genes into industrial strains of Saccharomyces require the use of dominant selectable markers, i.e. antibiotic or toxic compound resistance markers. Integration of these markers into the yeast genome is, however, not acceptable for commercial application due to the absence of long-term risk assessment and consumer resistance. A unique strategy for the integration of the S. pombe mae} and mae2 expression cassettes without the incorporation of any non-yeast derived DNA sequences was. The malo-ethanolic cassette, containing the S. cerevisiae PGK} promoter and terminator regions together with the S. pombe mae] and mae2 open reading frames, was integrated into the VRA3 locus of an industrial strain of Saccharomyces bayanus EC 1118 during co-transformation with a phleomycin-resistance plasmid, pUT332. After initial screening for phleomycin resistance, S. bayanus EC1118 transformants were cured of the phleomycin-resistance plasmid, resulting in the loss of non-yeast derived DNA sequences. After correct integration of the mae] and mae2 expression cassettes was verified, small-scale vinification in synthetic and Chardonnay grape must with stable transformants resulted in rapid and complete degradation of L-malic acid during the early stages of alcoholic fermentation. Integration and expression of the malo-ethanolic genes in S. bayanus ECll18 had no adverse effect on the fermentation ability of the yeast, while sensory evaluation and chemical analysis of the Chardonnay wines indicated an improvement in wine flavour compared to the control wines, without the production of any off-flavours.
AFRIKAANSE OPSOMMING: L-Appelsuur en wynsteensuur is die mees prominente organiese sure in wyn en speel 'n kritiese rol in die wynbereidingsproses en organoleptiese wynkwaliteit, insluitende die fisiese, biochemiese en mikrobiese stabiliteit van wyn. Die produksie van hoë-kwaliteit wyne berus op die vermoë van 'n wynmaker om die suurinhoud korrek aan te pas om sodoende 'n gebalanseerde produk met optimale geur en kleur te produseer. Saccharomyces rasse kan gewoonlik nie appelsuur volledig tydens alkoholiese gisting benut nie en dra dus nie noemenswaardig tot 'n verlaging van die totale suurinhoud van wyn by nie. Die mate van appelsuur afbraak deur Saccharomyces wissel egter van ras tot ras. Sekere Saccharomyces rasse kan 'n groter persentasie appelsuur afbreek, maar die onderliggende rede vir hierdie verskynsel is onbekend. Die onderliggende meganismes vir hierdie verskynsel is gedurende hierdie studie uitgelig na afloop van voorlopige transkripsionele regulerings studies op die malaatensiemgeen. In teenstelling hiermee kan S. pombe tot 29 gIl appelsuur via die malo-alkoholiese padweg afbreek waartydens appelsuur na pirodruiwesuur en CO2, en uiteindelik na alkoholonder fermentatiewe toestande omgeskakel word. Verskeie redes vir die swak afbraak van appelsuur deur Saccharomyces cerevisiae is voorgestel. Eerstens beskik S. cerevisiae nie oor 'n meganisme vir die aktiewe transport van appelsuur, soos in die geval van S. pombe nie, en is aangewese op die stadige opname van appelsuur deur eenvoudige diffusie. Tweedens het die S. cerevisiae malaatensiem 'n baie laer substraataffiniteit vir appelsuur (Km = 50 mM) in vergelyking met die van S. pombe (Km = 3.2 mM), wat verder bydra tot die swak afbraak van appelsuur in S. cerevisiae. Laastens dra die mitochondriale ligging van die S. cerevisiae malaatensiem in teenstelling met die sitoplasmiese ligging van die S. pombe malaatensiem, verder by tot die swak afbraak van appelsuur, aangesien die mitochondria onder fermentatiewe toestande negatief gereguleer word. Die malaatpermease geen (maely en malaatensiem geen (mae2) van S. pombe is gevolglik gekloneer en heteroloog in 'n laboratoriumras van S. cerevisiae onder die beheer van die konstitutiewe 3-fosfogliseraat kinase (PGKI) promoter- en termineerdervolgordes uitgedruk. 'n Sterk malo-alkoholiese fenotipe was duidelik tydens fermentasies met die rekombinante gis in sintetiese en Chardonnay druiwemos, met 'n gepaardgaande verhoging in alkoholvlakke. Funksionele uitdrukking van die malo-alkoholiese gene van S. pombe in 'n S. cerevisiae laboratoriumras het die weg vir die genetiese modifisering van industriële wynrasse van S. cerevisiae vir kommersiële wynfermentasie gebaan. Om 'n integrale deel van die gis te word, moet die malo-alkoholiese gene stabiel in die genoom van industriële wynrasse geïntegreer word. Genetiese manipulering van industriële wynrasse word egter bemoeilik deur die homotalliese, multi-ploïediese en prototrofiese aard van industriële Saccharomyces rasse. Transformasie en integrasie van heteroloë gene in industriële Saccharomyces rasse vereis die gebruik van dominante merkers, bv. weerstandbiedendheid teen antibiotika of ander gifstowwe. Integrasie van hierdie merkers in die gisgenoom is egter nie vir kommersiële toepassing aanvaarbaar nie weens die afwesigheid van langtermyn risikobepalings en verbruikersweerstand. Tydens hierdie studie is daar dus gepoog om industriële wynrasse met 'n unieke strategie geneties te verbeter sodat slegs gis-DNA tydens die integrasie van die S. pombe mae1 en mae2 uitdrukkingskassette in die gisgenoom opgeneem word. Die Malo-alkoholiese integrasiekasset wat slegs die S. pombe mae1, mae2 oopleesrame en die S. cerevisiae PGK1 promoter en termineerdervolgordes bevat, is in die URA3 lokus van Saccharomyces bayanus ECll18 geïntegreer tydens parallelle transformasie met 'n 'phleomycin' weerstandbiedendheidsplasmied. Na seleksie van transformante op 'phleomycin' -bevattende media, is die S. bayanus EC 1118 transformante in nieselektiewe kondisies opgegroei sodat verlies van die 'phleomycin' plasmied kon plaasvind. Integrasie van die mae1 en mae2 uitdrukkingskassette is bevestig en kleinskaalse fermentasies in sintetiese en druiwemos het 'n vinnige en doeltreffende afbraak van appelsuur in die vroeë fases van die alkoholiese fermentasie getoon. Integrasie en uitdrukking van die malo-alkoholiese gene in S. bayanus ECl118 het geen nadelige effek op die fermentasievermoë van die gis getoon nie, terwyl sensoriese en chemiese ontleding van die Chardonnay wyne 'n verbetering in aroma relatief tot die kontrole wyne getoon het, met die afwesigheid van enige afgeure.

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Duchêne, Eric. "Une exploration des possibilités génétiques pour l'adaptation de la vigne au changement climatique." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAJ059/document.

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Les effets du changement climatique ont d’ores et déjà été observés sur la vigne : avancement des stades de développement, augmentation des teneurs en alcool des vins, baisse excessive de leur acidité. Une des voies d’adaptation possible de la viticulture est la création de nouvelles variétés. J’ai caractérisé la variabilité phénotypique de 120 descendants de croisements entre Riesling (RI) et Gewurztraminer (GW) pour (1) les stades de développement, décrits à l’aide de sommes de températures (2) la capacité à accumuler des sucres dans les raisins (3) les paramètres de l’acidité des raisins. L’utilisation de marqueurs moléculaires sur l’ADN a permis de mettre en évidence des relations entre données génétiques et phénotypiques pour tous les caractères étudiés (QTLs ou Quantitative trait loci). La principale conclusion est que la variabilité génétique pour les paramètres de l’acidité des raisins est la voie à valoriser en priorité pour l’adaptation de la vigne au changement climatique
The effects of climate change have already been observed on the grapevine : advance of phenological stages, increase in the alcohol content of the wines, excessive decrease of their acidity. Breeding new varieties is one of the possible means of adaptation. I have characterized the phenotypic variability of 120 genotypes, offspring from crossings between Riesling (RI) and Gewurztraminer (GW)for (1) the developmental stages, described with heat sums (2) the ability to accumulate sugars in the berries (3) the parameters for acidity. The use of DNA molecular markers allowed the detection of quantitative trait loci (QTLs) for all the traits studied. The main conclusion is that the genetic variability for the parameters determining the acidity of the berries is the most promising for the adaptation of grapevine cultivation to climate change

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Chabert, Adèle. "Traitement biosourcé du Hêtre par la formation in situ de polyesters à base d’Acide Malique - Étude du procédé et des propriétés physiques conférées, du petit échantillon à l’échelle de la planche." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0252.

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Le bois est un matériau hygroscopique dont les dimensions varient avec les conditions hygrothermiques de l'environnement qui l'entoure. Une des essences les plus nerveuses en France est le hêtre. Il est très abondant en Europe, peu durable, et nécessite donc une protection additionnelle pour améliorer sa durabilité et étendre son utilisation. Ce travail de thèse a étudié plusieurs traitements biosourcés par la formation in situ de polyesters à base d'acide malique. Deux types d'alcool ont été utilisés, l'un ramifié, le glycérol, l'autre linéaire, le 1,4-butanediol, afin d'observer si une plus faible réticulation du polymère pouvait limiter la baisse de la résistance mécanique. Ce type de traitement est imprégné dans le bois en solution aqueuse et la cuisson (150°C-24h, dans la première approche) permet la polymérisation. Tous les traitements développés ont montré qu'ils apportaient au bois de hêtre des améliorations importantes. Au niveau des indicateurs de gains et de stabilité, un gain de masse d'environ 40%, un bulking supérieur à 20% pour du bois sec à l'air, une plus grande stabilité dimensionnelle, l'ASE, supérieure à 60%, et un retrait-gonflement total divisé par 3 ont été observés. Concernant les propriétés mécaniques, celles-ci ont aussi vu des modifications importantes, telles que la rigidité augmentée de 30 à 60% (MOE) et la dureté Brinell jusqu'à 65%. Cependant, le bois modifié a perdu de sa ductilité et présente un mode de rupture fragile avec un module de rupture (MOR) réduit de près de 30%. De plus, la mesure du profil de densité par atténuation de rayons-X a montré une distribution hétérogène du traitement, plus concentré au niveau des surfaces de l'échantillon plus qu'à cœur. Pour réduire la sévérité du traitement, le couple durée-température de la cuisson du bois imprégné a été étudié en suivant l'avancement de la réaction à différentes températures au moyen d'une ATG. Ainsi qu'en utilisant des catalyseurs et un mélange pré-polymérisé, MaGNW. Les résultats ont montré qu'une diminution de la durée de cuisson pourrait être réduite d'un facteur 3, de 24h à 8h, et ainsi être possible à 150°C avec catalyseurs, bien qu'un lessivage plus élevé soit alors observé pour ces traitements dans le bois. Une baisse de la température de cuisson pourrait être envisageable selon l'usage prévu du hêtre. Nous avons ensuite regardé la possibilité d'appliquer ce traitement à l'échelle d'une planche (up-scaling). Pour limiter l'hétérogénéité du traitement dans les planches, plusieurs pistes ont été étudiées. Celles-ci sont, la réduction de l'épaisseur de la planche, l'ajout d'une phase de séchage basse température avant la phase de cuisson, mais encore par l'utilisation du mélange pré-polymérisé, sans eau de solution, pour tenter de fixer le produit dans le bois au plus tôt de la cuisson. Les deux premières options ont montré les résultats les plus intéressants en améliorant l'homogénéité du traitement dans la planche. La troisième option conduit à une densification du matériau
Wood is a hygroscopic material whose dimensions will vary with the hygrothermal conditions of the surrounding environment. One of the wood species the most susceptible to dimensions variations in France is beech wood. It is very abundant in Europe, and has a low durability, requiring additional protection to improve it and extend its use. This thesis work studied several bio-based treatments by the in situ formation of malic acid-based polyesters. Two types of alcohols were used, one is ramified, the glycerol, and the other one is linear, the 1,4-butanediol, to observe if a lower crosslinking of the polymer could limit the decrease in mechanical strength. This type of treatment is impregnated in the wood in an aqueous solution and the curing (150°C-24h, in the first approach) enables the polymerization. All the treatments developed showed that they brought significant improvements to beech wood. In terms of gain and stability indicators, a mass gain of about 40%, a bulking greater than 20% for air-dried wood, as well as a greater dimensional stability, the ASE, over 60%, and a total shrinkage-swelling divided by 3 was observed. Regarding the mechanical properties, they also saw significant changes, such as the stiffness increased by 30% to 60% (MOE) and the Brinell hardness up to 65%. However, the modified wood has lost its ductility and showed a brittle mode of failure with a modulus of rupture (MOR) reduced by almost 30%. In addition, measurement of the density profile by X-rays attenuation showed a heterogeneous distribution of the treatment in the board thickness, more concentrated at the surfaces of the sample than at the core. To reduce the severity of the treatment, the time-temperature relationship of the wood curing was studied by monitoring the reaction progress at different temperatures using TGA analysis as well as using catalysts and a pre-polymerized mixture, MaGNW. The results showed that a lowering of the curing time could be possible by a factor 3, from 24h to 8h, and thus be possible at 150°C with catalysts, although higher leaching is then observed from these treatments into the wood. A lowering of the curing temperature could be considered depending on the intended use of the beech. We then looked at the possibility of applying this treatment at the board scale (up-scaling). Several avenues have been studied to limit the heterogeneity of the treatment in the boards. These are the reduction of the board thickness, the addition of a low temperature drying phase before the curing phase, as well as the use of the pre-polymer mixture, removing the aqueous phase of the solution, aiming to fix the product in the wood as soon as possible during curing. The first two options demonstrated the most interesting results in improving the homogeneity of the treatment in the board thickness. As for the third option, it led to a densified material

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12

Thomson, C. C. "Rootstock and canopy density effects on grape berry composition : organic acid composition, potassium content and pH." Lincoln University, 2006. http://hdl.handle.net/10182/772.

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The influence of rootstock and canopy density on grape berry composition was investigated over the summer of 2003-2004 on a commercial vineyard at Waipara, North Canterbury. This experiment was designed to investigate the influence of rootstock and canopy density on the acid composition, potassium (K) content and final pH of harvested fruit (Pinot Noir AM 10/5 Lincoln Selection). The trial block consisted of eight rootstocks laid out to an 8 x 8 latin square, each plot consisting of five vines of the same rootstock. Two canopy treatments were overlaid the block (down whole rows, assigned randomly, four rows to each treatment); one treatment allowed to grow naturally, in the other treatment the canopy was thinned removing double burst shoots and laterals. The bunch numbers were adjusted in the Unthinned canopy treatment (UCT) to match the Thinned canopy treatment (TCT). Information was gathered to assess: the canopy size and density (Pinot Quadrat Leaf Layer and Percent Gaps and canopy porosity), the plant yield (and berry size, berries per cluster, cluster weight, clusters per plant), plant K levels at flowering and veraison (from petioles and leaf blades) and berry composition at harvest (soluble solids (as brix), K, titratable acidity (TA), tartaric acid concentration, malic acid concentration and pH). The trial area was non-irrigated on clay loam soils and viticultural management was to best commercial practice. It was found that although rootstock influenced the levels of K in the plant and in the juice at harvest, the level of K in the juice did not influence pH in this experiment (range of rootstock juice K: 808 ppm to 928 ppm, l.s.d. = 75 ppm). The level of tartaric acid concentration in the juice was found to be the dominant influence on the level of pH in this experiment (rootstock pH range: 3.21 to 3.39, l.s.d. = 0.05). The juice concentration of tartaric acid was influenced by both rootstock (rootstock range 4.0 to 4.7 g/L, l.s.d = 0.4) and canopy density (UCT = 4.1, TCT = 4.7, l.s.d. = 0.4), decreased shading positively increasing the level of tartaric acid. The malic acid concentration in the juice was positively influenced by increasing canopy density (UCT = 4.7 g/L, TCT = 4.1 g/L, l.s.d = 0.4) and this played a minor role in the determination of pH in this experiment; an influence of rootstock on the level of malic acid concentration was found. The malic acid concentration strongly influenced the determination of TA (UCT = 11.0 g/L, TCT = 10.2 g/L, l.s.d = 0.5); tartaric acid concentration had a minor influence on the recorded TA. Attempts to characterise the influence of rootstock on malic acid, tartaric acid and pH were inconclusive. Rootstock was found to influence the canopy variables measured in this experiment and the recorded average plant yield. Crosses of Vitis rupestris were found to exhibit the most canopy vigour and those derived from Vitis berlandieri and Vitis riparia the least. The Canopy treatment did not show an influence over yield but the rootstock was found to influence plant yield, through the numbers of berries set in a cluster and the final harvest cluster weight. The influence of rootstock on pH may be described by the influence it exerts on canopy growth and yield but this was thought unlikely. Further research is required to describe the nature of the rootstock influence on K, malic acid, tartaric acid and pH.

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13

Lautrette, Guillaume. "Capsules hélicoïdales auto-organisées par repliement d’oligoamides aromatiques pour la reconnaissance moléculaire." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14850/document.

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La reconnaissance moléculaire constitue l’une des questions fondamentales les plus discutées dans le domaine de la chimie supramoléculaire. Cette thèse présente la conception, la synthèse et l’étude des propriétés de capsules hélicoïdales auto-organisées par repliement d’oligoamides aromatiques. Ces récepteurs sont constitués d’une chaîne oligomérique se repliant en hélice et comprenant une séquence d’unités codant pour des diamètres différents. Le repliement de l’oligomère donne naissance à une cavité pouvant accueillir des molécules invitées. La grande modularité des séquences, permettant une évolution contrôlée des structures des foldamères, donne lieu à la reconnaissance sélective et anticipée de substrats d’intérêts biologiques. Le phénomène d’encapsulation a été mis en évidence en solution par spectroscopie RMN et CD, et dans le solide par diffraction des rayons X
Molecular recognition is one of the major challenges of supramolecular chemistry. Here, we present the design, synthesis and study of helical capsules properties self-organised by aromatic oligoamide folding. These receptors consist of oligomeric chains that fold into a helical conformation and comprise of a sequence of units which code for different diameters. Oligomeric folding defines a cavity which can recognize guests. The great modularity of the sequences has allowed a controlled evolution of foldamer structure resulting in the selective and predict recognition of biological substrates. The phenomenon of encapsulation was demonstrated in solution by NMR and CD spectroscopy and in the solid state by X-ray diffraction

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Ayoub, Nadim. "Synthèse et valorisation des dérivés furaniques issus de la biomasse par oxydations sélectives." Electronic Thesis or Diss., Compiègne, 2022. http://www.theses.fr/2022COMP2677.

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La biomasse fait partie des ressources renouvelables qui peuvent répondre durablement à nos besoins de production de carburants, de produits chimiques et de matériaux. En effet, la biomasse non comestible telle que la lignocellulose a attiré l'attention des chercheurs et des scientifiques au cours des dernières décennies en tant qu'alternative renouvelable. Le furfural et le 5-hydroxyméthylfurfural (HMF), dérivés de la déshydratation des pentoses et des hexoses respectivement, sont produits à plusieurs millions de tonnes par an. Ces derniers composés sont donc des molécules plateformes et représentent un intérêt majeur dans le cadre du développement durable. Ce travail vise à explorer des méthodes nouvelles et vertes pour l'oxydation sélective du furfural et de HMF afin de produire des produits biosourcés à haute valeur ajoutée tels que le 2,5-diformylfurane (DFF), l'acide maléique et l'acide succinique. Tout d'abord, un système alternatif d'oxydation de HMF a été présenté, sans l'utilisation de catalyseurs de métaux nobles, de hautes pressions et évitant la production de déchets toxiques. Dans ce contexte, l'oxydation à l'échelle du gramme de HMF conduit à la formation de DFF. Cette réaction a été catalysée par l'acide 2-iodobenzènesulfonique en présence d'Oxone®. Dans des conditions expérimentales optimisées, la conversion du HMF s'est avérée être de 100%, tandis que le rendement et la sélectivité du DFF étaient vers 90%. Par la suite, nous avons démontré un processus sans catalyseur pour la synthèse à l'échelle du gramme de l'acide maléique à partir de furfural en utilisant des irradiations ultrasonores à hautes fréquences. Une sélectivité de 70% en acide maléique avec 92% de conversion du furfural a été obtenue sans aucun catalyseur dans des conditions douces en utilisant H2O2 comme oxydant. Notre approche alternative permet l'utilisation de la biomasse au lieu du pétrole pour synthétiser l'acide maléique à partir du furfural dans un processus écologique et économe en énergie. Enfin, un nouveau procédé catalytique est développé en utilisant des nanoparticules de magnétite, comme catalyseur métallique bon marché et non noble, et du peroxyde d'hydrogène pour l'oxydation du furfural en acide succinique. La conversion totale du furfural a été obtenue avec 67% de rendement en acide succinique dans des conditions douces
Biomass is one of the renewable and green resources that can sustainably meet our needs for the production of fuels, chemicals and materials. Indeed, nonedible biomass such as lignocellulose has attracted attention of researchers and scientists in the last decades as a renewable alternative. Furfural and 5-hydroxymethylfurfural (HMF), derived from the dehydration of pentoses and hexoses respectively, are produced in multimillion ton-scale annually. The latter compounds are, therefore, platform molecules and represent a major interest in the context of sustainable development. This work aims to explore novel and green methods for the selective oxidation of furfural and HMF to produce high value-added bio-sourced products such as, 2,5-diformylfuran (DFF), maleic acid and succinic acid. First, an alternative system of HMF oxidation was presented, without the use of noble metal catalysts, high pressures and avoiding the production of toxic wastes. In this context, the gram-scale oxidation HMF leads to the formation of DFF. This reaction was catalyzed by 2-iodobenzenesulfonic acid in the presence of Oxone®. Under optimized experimental conditions, the HMF conversion was found to be 100%, while the DFF yield and selectivity were almost 90%. Subsequently, we demonstrated a catalyst-free process for the gram-scale synthesis of maleic acid from furfural using high frequency ultrasound irradiations. A 70% selectivity of maleic acid with 92% of furfural conversion were achieved without any catalyst under mild conditions using H2O2 as oxidant. Our alternative approach enables the use of biomass instead of petroleum to synthesize maleic acid from furfural in an eco-friendly and energy-efficient process. At last, a novel catalytic process is developed using magnetite nanoparticles, as a cheap and non-noble metal catalyst, and hydrogen peroxide for the oxidation of furfural into succinic acid. Total conversion of furfural was achieved with 67% of succinic acid yield under mild conditions

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15

Li, Shengchun. "Antioxidant systems and protein phosphatases in metabolic and signaling responses to oxidative stress." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA112086.

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Le stress oxydant est un acteur clé dans les réponses des plantes à des conditions contraignantes. En raison de la complexité de la régulation de l’état redox cellulaire, il reste beaucoup à élucider concernant les interactions entre différentes composantes dans ces conditions. Grâce à une approche de génétique inverse basée sur un mutant d’Arabidopsis déficient en catalase (cat2) qui présente des modifications d’état redox prévisibles et bien définies, cette étude a exploré les interactions entre le stress oxydant et (1) un gène spécifique impliqué dans la déphosphorylation des protéines, (2) des enzymes spécifiques impliquées dans les systèmes antioxydants réducteurs. Les résultats obtenus révèlent que la sous-unité B'γ de la protéine phosphatase de type 2A (PP2A-B'γ) est importante dans la détermination des phénotypes et des réponses de défense photopériode-dépendantes chez cat2. En conditions de jours courts (SD), un double cat2 pp2a-b'γ mutant montrait une gamme de réponses qui n’étaient pas observées chez cat2. Ces effets comprenaient l’apparition de lésions ainsi que l’accumulation de l’acide salicylique et d’autres composés de défense. Des analyses métabolomiques et protéomiques ont permis de démontrer que ces effets étaient accompagnés de modifications de l’abondance de métabolites et protéines spécifiques, ainsi que des changements dans le statut de phosphorylation de certains polypeptides. Dans un deuxième volet du travail, l’importance d’une enzyme productrice du NADPH a été évaluée en produisant des doubles cat2 nadp-me2 mutants chez lesquels l’isoforme majeure de l’enzyme malique cytosolique n’est plus exprimée. Malgré une induction de cette enzyme par le stress oxydant aux niveaux de transcrits et d’activité, et une diminution importante de l’activité foliaire associée aux mutations nadp-me2, peu de différence a été observée entre les lignées cat2 et cat2 nadp-me2. De même, la mutation nadp-me2 n’a pas affecté la réponse phénotypique de plantes exposées à l’ozone. Dans la troisième partie du travail, le couplage entre les pools ascorbate et glutathion lors du stress oxydant a été exploré par l’introduction de mutations pour la déshydroascorbate réductase (DHAR) dans le fond génétique cat2. L’activité extractible de cette enzyme a été diminuée à des niveaux très faibles chez des lignées portant à la fois les mutations dhar1 et dhar3. Cependant, peu de différence a été observée dans les phénotypes et les statuts d’ascorbate et de glutathion chez un triple mutant cat2 dhar1 dhar3 par rapport à cat2. Des analyses préliminaires d’un quadruple cat2 dhar1 dhar2 dhar3 mutant semblent pourtant indiquer que les trois DHARs jouent des rôles fonctionnellement redondants dans le stress oxydant. Dans son ensemble, ces travaux apportent des données nouvelles sur les enzymes qui régulent les réponses aux stress oxydants et ont généré des outils intéressants pour des études ultérieures
Oxidative stress is a key player in plant responses to challenging environmental conditions. The intricate nature of the regulation of cellular redox state means that much remains to be elucidated on interactions between different components in these conditions. By using a genetic approach based on a catalase-deficient Arabidopsis mutant (cat2) that presents well-defined, predictable changes in redox state, this study explored interactions between oxidative stress and (1) a specific gene involved in protein dephosphorylation, and (2) specific enzymes involved in the antioxidative/reducing system. The results showed that protein phosphatase 2 subunit B'γ (PP2A-B'γ) is involved in determining day length-dependent phenotypes and related defense responses in cat2. A cat2 pp2A-B'γ double mutant showed a range of responses that were not observed in cat2 grown in short days, including lesion formation and accumulation of salicylic acid (SA) and related metabolites. Metabolomics and proteomics analyses showed that these effects were associated with altered abundance of specific metabolites and proteins, as well as changes in protein phosphorylation status. A second part of the study investigated the importance of NADP-generating enzymes in oxidative stress by production of cat2 nadp-me2 double mutants, in which the cytosolic isoform of NADP-malic enzyme is knocked out. Although NADP-ME2 was shown to be induced by oxidative stress, and mutants for this gene had much decreased leaf NADP-malic enzyme activity, no effects on cat2 phenotypes or redox profiles were apparent. Similarly, phenotypic responses to ozone were not affected in an nadp-me2 single mutant. In the third part, coupling between ascorbate and glutathione pools during oxidative stress was investigated by introduction of loss of function mutations for dehydroascorbate reductase (DHAR) into the cat2 background. In lines carrying a combination of dhar1 and dhar3 mutations, extractable leaf activity was decreased to very low levels. Despite this, cat2 dhar1 dhar3 and cat2 phenotypes and ascorbate and glutathione pools were similar. However, preliminary functional analysis of a cat2 dhar1 dhar2 dhar3 quadruple mutant suggested that the three DHARs play functionally redundant roles in oxidative stress. Overall, the work provides new data on enzymes that regulate responses to oxidative stress and has produced interesting genetic tools for further study

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16

Zhang, Baohua. "Metabolic Engineering for Fumaric and Malic Acids Production." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1346338118.

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17

Barouti, Ghislaine. "New poly(hydroxyalkanoate)-based copolymers : from synthesis to tunable self-assembled systems." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S064/document.

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Les copolymères à blocs amphiphiles s’auto-assemblent en solution aqueuse grâce à l’association de leurs segments hydrophobes. Les nanoparticules formées à partir de copolymères biocompatibles et biodégradables tels que les poly(hydroxyalkanoates) (PHAs) sont particulièrement attractives pour la conception de systèmes à libération prolongée de principes actifs. La relation entre la composition/structure chimique du copolymère, ses propriétés d’auto-assemblage et ses effets sur les cellules in-vitro doit être étudiée. Des copolymères à blocs poly(acide malique)-b-poly(3-hydroxybutyrate) (PMLA-b-PHB), PMLA-b-PHB-b-PMLA et poly(triméthylène carbonate)-b-poly(acide-malique) (PTMC-b-PMLA) ont été synthétisés par polymérisation par ouverture cycle (ROP) des monomères correspondants, suivie d’une hydrogénolyse. Une gamme de copolymères bien définis, caractérisés par spectroscopie RMN 1H, 13C{1H}, HSQC, HMBC, et DOSY, par analyses SEC, DSC, TGA, et mesure des angles de contact, présentant des balances hydrophile/hydrophobe modulables, a été obtenue grâce au control précis de la fraction hydrophile f (11-82%). Des auto-assemblages modulables ont été formés par nanoprécipitation des copolymères en l’absence d’agent tensio-actif. De larges agrégats ainsi que des micelles cœur-couronne (Rh = 16-335 nm) ont été obtenus en fonction du copolymère utilisé (dibloc vs. tribloc). Des micelles stables pendant 10 jours à 37 °C en solution aqueuse ont été obtenues pour les copolymères avec f allant jusqu’à 50%. Les copolymères PMLA-b-PHB et PTMC-b-PMLA n’ont pas révélé de toxicité aigüe in-vitro. De plus, l’utilisation du PHB a avantageusement permis de diminuer la captation des nano-objets par les macrophages et d’augmenter la captation par les cellules hépatiques
Amphiphilic block copolymers are able to form self-assembled systems in aqueous solution by association of their hydrophobic segments. Nanoparticles formed from biodegradable and biocompatible polymers such as poly(hydroxyalkanoate) copolymers are particularly attractive for drug delivery applications. The relationship between the chemical structure/composition of the macromolecule, its self-assembly properties and its effect on cells in-vitro has to be studied.The synthesis of poly(-malic acid)-b-poly(3-hydroxybutyrate) (PMLA-b-PHB), PMLA-b-PHB-b-PMLA, and poly(trimethylene carbonate)-b-poly(-malic acid) (PTMC-b-PMLA) was established through the ring-opening polymerization (ROP) of the corresponding monomers followed by hydrogenolysis. A range of well-defined copolymers characterized by 1H, 13C{1H}, HSQC, HMBC, DOSY NMR spectroscopy, SEC, DSC, TGA, contact angle analyses, with tunable hydrophilic/hydrophobic balance were thus obtained through the precise control of the hydrophilic weight fraction f (11-82%). Tunable self-assembled systems were obtained by nanoprecipitation of the amphiphilic PHA-based copolymers without the use of a surfactant. Large aggregates and core-shell micelles (Rh = 16-335nm) were obtained depending on the polymer topology. PHB-based copolymers with f up to 50% formed highly stable micelles at 37 °C over a period of 10 days in aqueous solution. PMLA-b-PHB as well as PTMC-b-PMLA copolymers revealed no acute in-vitro cytotoxicity. The use of PHB as hydrophobic segment enabled to minimize the non-specific scavenging by macrophages cells while the cellular uptake by hepatocytes was favored

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18

Queji, Mary Dias. "DETERMINAÇÃO DE AÇÚCARES SIMPLES, ÁCIDO MÁLICO E COMPOSTOS FENÓLICOS TOTAIS EM BAGAÇO DE MAÇÃ POR ESPECTROSCOPIA NO INFRAVERMELHO E MÉTODO DE CALIBRAÇÃO MULTIVARIADA." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2008. http://tede2.uepg.br/jspui/handle/prefix/662.

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Made available in DSpace on 2017-07-21T18:53:09Z (GMT). No. of bitstreams: 1 Mary Dias Queji.pdf: 909281 bytes, checksum: 0364cd27c13b09019850a0944168a898 (MD5) Previous issue date: 2008-04-05
The agro industry of the apple generates, during the processing, the pomace which is considered the main by-product. Studies show that of the total amount of fruit that is processed to obtain the apple juice, 20 to 40 correspond to this by-product, which, is usually destined as a complement in animal feed or delivered onto the soil as organic fertilizer. The chemical composition, in moist base, is constituted by moisture (80), fibers (5) and soluble solids (14) represented, mainly, by fructose, glucose and sucrose, as well as, by organic acids, represented, in the most part by malic acid. The apple pomace also presents phenolic compounds that are target nutrients of great sensory and nutritional importance. Therefore, the quantification of its constituents represents an important source of data in the characterization of apple pomace for biotechnological purposes, seeking to attribute an appropriate use for this by-product. The conventional methodologies used for the quantification of sugars, organic acids and total phenols, although being part of the routine analyses in the quality control laboratories, are onerous, time consuming and generate residues. The aim of this study was to develop a fast, versatile analytical technique, of low cost and no pollutant, using the diffuse reflectance infrared spectroscopy (DRIFTS) allied to methods of multivariate calibration (PLSR). For the construction of the multivariate models, the averages of the concentrations of the simple sugars, malic acid and total phenols were used, obtained by the conventional methodologies, as well as the data in the medium infrared spectroscopy (MID) and near (NIR), obtained in duplicate, and of the 52 spectra obtained for the samples of apple pomace, 47 made part of the set calibration and 5 of the set validation. The regression models for the prediction of the concentration of fructose, sucrose, total phenols and malic acid obtained better results in MID, with averages of relative standard errors of 3.9 (with 5 Latents Variable), 6.6 (with 5 Latents Variable), 6.4 (with 4 Latents Variable) and 5.9 (with 5 Latents Variable), respectively. Already the best capacity prediction for glucose concentration was obtained by NIR, in which the average of relative standard error was 7.4 (with 6 Latents Variable). The obtained results demonstrate the good capacity of prediction of the multivariate models based in infrared spectroscopy and characteristic advantages of the association DRIFTPLSR.
A agroindústria da maçã gera, durante o processamento, o bagaço que é considerado o principal subproduto deste setor. Levantamentos mostram que da quantidade total de fruta que é processada para a obtenção do suco de maçã, 20 a 40 correspondem a este subproduto, que, normalmente, é destinado como complemento na alimentação animal ou dispensado no solo como adubo orgânico. Sua composição química, em base úmida, é constituída por umidade (80), fibras (5) e sólidos solúveis (14), estes últimos representados, principalmente, por frutose, glucose e sacarose, bem como, ácidos orgânicos, representados, majoritariamente pelo ácido málico. O bagaço da maçã também apresenta compostos fenólicos, que são fito-nutrientes de grande importância sensorial e nutricional. Portanto, a quantificação desses constituintes representa uma importante fonte de dados na caracterização do bagaço de maçã para finalidades biotecnológicas, visando atribuir um fim mais nobre a este subproduto. As metodologias convencionais empregadas para a quantificação de açúcares, ácidos orgânicos e fenóis totais, embora façam parte das análises de rotina nos laboratórios de controle de qualidade, são onerosas, demoradas e geram resíduos. O objetivo deste trabalho foi desenvolver uma técnica analítica rápida, versátil, de baixo custo e não poluente. Para tal, utilizou-se a espectroscopia no infravermelho por refletância difusa (DRIFTS) aliada a métodos de calibração multivariada (Regressão de Mínimos Quadrados Parciais - PLSR). Para a construção dos modelos multivariados, foram utilizadas as médias das concentrações dos açúcares simples, ácido málico e fenóis totais, obtidas pelas metodologias convencionais, bem como, os dados de espectroscopia no infravermelho médio (MID) e próximo (NIR). Os espectros foram obtidos em duplicata, sendo que dos 52 espectros das amostras de bagaço de maçã, 47 fizeram parte do conjunto de calibração e 5 do conjunto de validação externa. Os modelos de regressão para a previsão da concentração de frutose, sacarose, fenóis totais e ácido málico obtiveram melhores resultados no MID, com médias de erro padrão relativo de 3.9 (com 5 Variáveis Latentes), 6.6 (com 5 Variáveis Latentes), 6.4 (com 4 Variáveis Latentes) e 5.9 (com 5 Variáveis Latentes), respectivamente. Já a melhor capacidade de previsão para a concentração de glucose foi obtida pelo NIR, na qual a média de erro padrão relativo foi de 7.4 (com 6 Variáveis Latentes). Os resultados obtidos demonstram a boa capacidade de previsão dos modelos multivariados fundamentados em espectroscopia no infravermelho e vantagens características da associação DRIFT-PLSR.

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19

Saayman, Maryna. "Characterisation of the malate transporter and malic enzyme from Candida utilis." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/16520.

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Dissertation (PhD)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Yeast species differ remarkably in their ability to degrade extracellular dicarboxylic acids and to utilise them as their only source of carbon. The fission yeast Schizosaccharomyces pombe effectively degrades L-malate, but only in the presence of an assimilable carbon source. In contrast, the yeast Saccharomyces cerevisiae is unable to effectively degrade L-malate, which is ascribed to the slow uptake of L-malate by diffusion. In contrast, the yeast Candida utilis can utilise L-malate as the only source of carbon and energy, but this is subject to substrate induction and catabolite repression. Very little research has been done on a molecular level in C. utilis and only a few of its genes have been studied. In this study, we have shown that the yeast C. utilis effectively degraded extracellular L-malate and fumarate, but in the presence of glucose or other assimilable carbon sources, the transport and degradation of these dicarboxylic acids was repressed. The transport of both dicarboxylic acids was shown to be strongly inducible by either L-malate or fumarate and kinetic studies suggest that the same transporter protein transports the two dicarboxylic acids. In contrast, S. pombe effectively degraded extracellular L-malate, but not fumarate, only in the presence of glucose or other assimilable carbon sources. The S. pombe malate transporter was unable to transport fumarate, although fumarate inhibited the uptake of L-malate. In order to clone the C. utilis dicarboxylic acid transporter, a cDNA library from C. utilis was constructed using a number of strategies to ensure representativeness and high transformation frequencies. The cDNA library was transformed in a S. cerevisiae strain carrying a plasmid containing the S. pombe malic enzyme gene (mae2) to allow screening for a malate-degrading S. cerevisiae clone. However, no positive clones that would indicate the successful cloning of the C. utilis malate transporter were obtained. The C. utilis malic enzyme gene, CuME, was subsequently isolated from the cDNA library based on conserved sequence homologies with the genes of S. cerevisiae and S. pombe, and characterised on a molecular and biochemical level. Sequence analysis revealed an open reading frame of 1926 bp, encoding a 641 amino acid polypeptide with a predicted molecular weight of 70.2 kDa. The optimum temperature for the C. utilis malic enzyme was 52°C and the enzyme was stable at 50°C for 2 hours. The inferred amino acid sequence showed significant homology with the malic enzymes of S. pombe and S. cerevisiae. Expression of the CuME gene is subject to glucose repression and substrate induction, as was observed for the dicarboxylic acid transporter from C. utilis. The CuME gene was successfully coexpressed with the S. pombe malate permease gene (mae1), resulting in a recombinant strain of S. cerevisiae able to effectively degrade L-malate.
AFRIKAANSE OPSOMMING: Daar is ’n merkwaardige verskil in die vermoë van verskillende gisspesies om ektrasellulêre dikarboksielsure af te breek en dit as enigste bron van koolstof te benut. Die splitsingsgis Schizosaccharomyces pombe kan L-malaat effektief afbreek, maar slegs in die teenwoordigheid van ’n ander benutbare koolstofbron. In teenstelling hiermee is dit vir die gis Saccharomyces cerevisiae onmoontlik om L-malaat effektief af te breek en te benut, wat hoofsaaklik toegeskryf kan word aan die stadige opname van L-malaat deur middel van diffusie. Die gis Candida utilis kan egter L-malaat as die enigste bron van koolstof en energie benut, maar dit is onderhewig aan substraat-induksie en kataboliet onderdrukking. Baie min navorsing op molekulêre vlak is tot hede in C. utilis uitgevoer en slegs ’n paar gene in hierdie gis is al bestudeer. In hierdie studie het ons aangetoon dat die gis C. utilis L-malaat en fumaraat effektief afbreek, maar dat glukose of ander benutbare koolstofbronne die opname en afbraak van hierdie dikarboksielsure onderdruk. Die opname van beide dikarboksielsure is sterk induseerbaar deur L-malaat óf fumaraat, terwyl kinetiese studies toon dat beide dikarboksielsure deur dieselfde transporter-proteïen vervoer word. In teenstelling hiermee kan S. pombe ekstrasellulêre L-malaat, maar nie fumaraat nie, in die teenwoordigheid van glukose of ’n ander benutbare koolstofbron effektief afbreek. Die S. pombe L-malaat transporter was nie in staat om fumaraat te vervoer nie, alhoewel fumaraat die opname van L-malaat onderdruk het. Ten einde die dikarboksielsuur transporter van C. utilis te kloneer, is verskeie strategieë gevolg ten einde ’n cDNA-biblioteek van C. utilis te konstrueer wat verteenwoordiging en hoë transformasie-frekwensies kan verseker. Die cDNA-biblioteek is getransformeer in ’n S. cerevisiae ras wat die S. pombe malaatensiem geen (mae2) bevat om die sifting van ’n S. cerevisiae kloon wat malaat effektief kan afbreek, moontlik te maak. Geen positiewe klone wat dui op die klonering van die C. utilis malaat transporter kon egter gevind word nie. Die C. utilis malaatensiem geen, CuME, is vervolgens van uit die cDNA biblioteek geïsoleer deur van gekonserveerde DNA-homologie met S. cerevisiae en S. pombe gebruik te maak, en op molekulêre en biochemiese vlak gekarakteriseer. DNA-volgordebepaling het ’n oopleesraam van 1926 bp onthul, wat kodeer vir ’n 641 aminosuur polipeptied met ’n verwagte molekulêre gewig van 70.2 kDa. Die optimale temperatuur van die C. utilis malaatensiem was 52°C en die ensiem was vir 2 ure stabiel by 50°C. Die afgeleide aminosuurvolgorde het beduidende homologie met die malaatensieme van S. pombe en S. cerevisiae getoon. Die CuME geen is suksesvol saam met die S. pombe malaat permease geen (mae1) uitgedruk om ’n rekombinante S. cerevisiae ras te genereer wat in staat is om L-malaat effektief af te breek.

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Homola, Ondřej. "Acid Drop Age." Master's thesis, Vysoké učení technické v Brně. Fakulta výtvarných umění, 2015. http://www.nusl.cz/ntk/nusl-232447.

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21

Wang, Lili. "Adsorption of (poly)maleic acid and aquatic fulvic accids by goethite." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1302190533.

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22

Yeniay, Secil. "Sulfonated Styrene-co-maleic Acid And Its Derivatives As Superplasticizers In Concrete." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609455/index.pdf.

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In the past three decades, a new group of concrete admixtures, termed &ldquo
superplasticizers&rdquo
, were introduced to the concrete industry. They have gained wide acceptance because of their many advantages. The addition of superplasticizers to concrete improves the workability and strength of concrete. In this study, the effect of the chemical structure of poly (4-styrenesulfonic acid-co-maleic acid) sodium salt (SSAMA), which contains both sulfonic and carboxylic acid groups, which is a new superplasticizer, was analyzed. Two different molecular weights of PEG (polyethylene glycol monomethyl ether) were grafted to this water-soluble copolymer at different weight compositions. The structures of synthesized copolymers were verified by FTIR and NMR analyses. The molecular weight difference of the grafted copolymers with different side chain lengths was determined by dilute solution viscosimetry. The effects of chemical structure of grafted copolymers on the fluidity of cement paste and the mechanical properties of the mortars were investigated. The zeta potential measurements revealed the interactions between the cement particles and polycarboxylate type superplasticizers. The maximum fluidity was achieved for the PEG grafted copolymer with the weight ratio 3:3. The mechanical properties of this copolymer showed the highest flexural and compressive strength compared to other copolymers. The addition of various Li salts to SSAMA affected the ionic medium, therefore, the dispersion performance of cement paste and the mechanical properties of the mortars improved. The mixture of LiCl: SSAMA in 1:1 mol ratio exhibited the maximum fluidity compared to other Li salts and their compositions. This mixture gave the highest flexural strength but the mixture of Li2CO3 in 1:1 composition gave the highest compressive strength in each salt mixtures.

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23

Charlton, Jack. "Solubilisation and characterisation of G-protein-coupled receptors using styrene maleic acid polymer." Thesis, University of Birmingham, 2016. http://etheses.bham.ac.uk//id/eprint/6525/.

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Detergent-free solubilisation using a polymer of styrene maleic acid (SMA) has proven useful in the study of membrane proteins. SMA was employed to solubilise G-protein-coupled receptors (GPCRs) from mammalian cells, into SMA lipid particles (SMALPs). Optimal SMALP solubilisation conditions were determined to be 2 % (w/v) SMA, at 37 °C for 1 h retaining wildtype (WT)-like pharmacological profiles and conferring improved stability on GPCRs over detergent micelles. Endoplasmic reticulum (ER)-retention motifs –KDEL and –KHILFRRRRRGFRQ were found not to be applicable to all proteins. Study of SMALP-solubilisation of intracellular membranes was prevented by the inability to retain the adenosine 2a receptor (A2aR) in the ER. A cysteine-nul A2aR construct was produced containing two reporter groups and behaved as WT-A2aR. This construct is ready for use in fluorescence studies to further understanding of A2aR and the use of SMALPs in biophysical techniques. A range of GPCRs, from different GPCR subfamilies, were SMALP-solubilised with retention of ligand binding capability. Methods were successfully developed to reduce non-specific binding arising from ionic interactions of ligand and SMA. Finally, in a world first, the SMA analogue styrene maleimide, was shown to solubilise GPCRs with retention of ligand binding capability.

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24

Malibo, Petrus Molaoa. "Development of heterostructured tin oxide nanocatalysts for the synthesis of bio-based maleic acid." University of Western Cape, 2021. http://hdl.handle.net/11394/8438.

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Philosophiae Doctor - PhD
Maleic acid (MA) is a key intermediate for the synthesis of polyester resins, surface coatings, lubricant additives, plasticizers, copolymers, pharmaceuticals and agricultural chemicals. The current industrial production of MA is an energy-intensive gas-phase oxidation process of n-butane. The dwindling fossil resources and environmental issues have brought about a worldwide paradigm shift from fossil feedstocks to biomass resources for the sustainable production of fuel and chemicals. Furfural (FFR) and 5-hydroxymethylfurfural (HMF) are excellent biomass-derived platform chemicals, which present an alternative route for the production of renewable bio-based MA. There has been considerable success achieved in the oxidation of furfural and HMF to maleic acid and maleic anhydride with different catalysts in recent years.

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25

Issaadi, Kahina. "Étude des propriétés thermiques et de la morphologie des nanobiopolymères à base de poly acide lactique : effet de la composition et de la nature de la nanocharge." Thesis, Lorient, 2015. http://www.theses.fr/2015LORIS388/document.

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La thèse porte sur l’étude de la morphologie et des différentes propriétés thermiques, mécaniques et barrières à la vapeur d’eau des nanobiocomposites à base de poly acide lactique (pla). La première partie est consacrée au greffage de l’anhydride maléique (am) sur le poly acide lactique plagma et à la mise en oeuvre de nanobiocomposites pla/cloisites, plagma/cloisites et pla/plagma/cloisites en utilisant deux cloisites® différentes (c20a et c30b), préparés par voie fondue. Au travers des différentes techniques utilisées, les résultats révèlent que les nanobiocomposites pla/cloisites élaborés se caractérisent par une morphologie mixte intercalée-exfoliée. L’ensemble des échantillons élaborés indiquent une meilleure dispersion de la cloisite apolaire c20a en présence de l’anhydride maléique et la réagrégation de la cloisite polaire c30b et par conséquent, l’amélioration à la fois des propriétés mécaniques et barrières à la vapeur d’eau des nanobiocomposites à base de la c20a. La seconde partie traite l’influence des groupements fonctionnels d’oxyde de graphène synthetisé au laboratoire et de graphène fonctionnalisé époxy commercialisé et fournit par nanovia (france) sur la dispersion des nanofeuillets de graphène au sein de la matrice pla, en présence ou en absence du compatibilisant plagma. L’étude révèle que la présence du compatibilisant améliore la dispersion de deux nanocharges étudiées. Le maximum des performances rhéologiques indiquant la meilleure dispersion de la nanocharge est enregistré pour une faible quantité d’oxyde de graphène possédant plus de groupements fonctionnels contenant l’atome d’oxygène. Les propriétés thermiques et barrières ont été considérablement améliorées avec l’incorporation des deux nanocharges et en présence de l’agent compatibilisant plagma. L’étude montre aussi que les propriétés mécaniques en traction des nanobiocomposites à base de graphène fonctionnalisé époxy (gfe) ont été améliorées en présence du plagma
The thesis focuses on the study of the morphology and thermal, mechanical and barrier properties of the nanobiocomposites based on poly lactic acid (pla). The first part is devoted to the grafting of maleic anhydride (ma) on the poly lactic acid plagma and the elaboration of the nanobiocomposites pla/cloisites, plagma/cloisites and pla/plagma/cloisitres using two different cloisites (c20a and c30b), prepared by melt intercalation and the characterization of the main properties. The results indicate that the pla/cloisites nanobiocomposites exhibit a mixed intercalated-exfoliated morphology. All the prepared samples showed an improvement in both thermal, mechanical and barrier properties in the presence of the nanofiller. All prepared samples show better dispersion of apolar cloisite (c20a) in the presence of maleic anhydride and reaggregation of the polar cloisite (c30b) and therefore, the improvement of both the mechanical and barrier properties of the nanobiocomposites based on c20a. The second section discusses the effect of the functional groups of graphene oxide synthetized in the laboratory and the graphene fonctionnalized epoxy marketed and supplied by nanovia (france) on the dispersion of the graphene nanofillers in the pla matrix. The study reveals that the presence of compatibilizer improves the dispersion of two studied nanofillers. Maximum rheological performance indicating better dispersion of the nanofiller is registered for a small amount of graphene oxide (og) with more functional groups containing oxygen atom. The thermal and barriers properties have been considerably improved with the incorporation of two nanofillers and in the presence of plagma compatibilizer. The study also shows that the tensile properties of the pla containing graphene functionalized epoxy (gfe) were improved in the presence of plagma

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26

Wang, Yutong. "The role of accessory proteins in controlling the thyroid hormone regulation of transcription of the malic enzyme gene." Morgantown, W. Va. : [West Virginia University Libraries], 2001. http://etd.wvu.edu/templates/showETD.cfm?recnum=1793.

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Thesis (Ph. D.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains vii, 106 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 83-102).

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27

Lin, Yu-pin. "Over-expression and biophysical characterisation of membrane proteins solubilised in a styrene maleic acid polymer." Thesis, University of Birmingham, 2011. http://etheses.bham.ac.uk//id/eprint/1738/.

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Membrane proteins are the gateways into cells and therefore a critical part of pharmaceutical research. Membrane proteins, in fact, have been shown to be the target of over 50% of all medicinal drugs. The development of drugs that acts on membrane proteins, however, has been limited by the lack of high resolution structural data. This lack of information results from a lack of a generic method to extract active membrane proteins from the cell membrane. We have developed a novel styrene maleic acid (SMA) / lipid particle system termed SMALP that preserves the structural and functional integrity of membrane proteins. We have optimised this system and used it to solubilise two membrane proteins with different architectures and functions. The first, human adenosine 2a receptor (A2aR), is a G-protein coupled receptor, a 7 transmembrane helix protein that is involved in cell signalling, whereas the second, FtsZ-interacting protein A (ZipA), is a protein involved in bacterial cell division that contains a single transmembrane domain. In this project, standardised purification protocols were developed that produced pure proteins without the need to add any detergents. The subsequent biophysical characterisation that included circular dichroism, mass spectrometry and sedimentation velocity analytical ultracentrifugation indicated that these purified SMALP solubilised proteins were natively folded once encapsulated. The activities of both proteins were then tested and shown to be close to that expected for the intact proteins in the cell membrane. Taken together these data suggest that the SMALP system offers the solution to membrane protein purification into the future.

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28

Alramadan, Ghada. "The Effect of Styrene-Maleic Acid (SMA) Copolymers on Solubilizing Lipid Bilayers and Forming Nanodiscs." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4843.

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Cell membranes, or plasma membranes, play an essential role in the structure and the function of living cells. In 1972, the fluid mosaic membrane model was the first unifying paradigm of membrane structure. It is no longer considered adequate because evidence of many non-homogeneous lipid structures in both natural and model membranes have been discovered over the past thirty years. The field of membrane biophysics now uses updated versions of the mosaic model, which consists of the complex mixture of different lipid species. The lipid species found in natural membranes produce a range of dynamic, laterally segregated, non-homogeneous domains, which exist on time scales ranging from microseconds to minutes. The cell membrane is an enclosing or separating membrane that acts as a selectively permeable barrier within living things. It consists of the phospholipid bilayer with associated embedded proteins, integral (intrinsic) and peripheral (extrinsic) proteins used for various biological activities. Proteins, especially integral membrane proteins, perform a range of key functions vital to the cell, such as controlled movement of molecules across lipid bilayers, as well as participating in cell signaling and motility. The major obstacle to studying membrane proteins is the tendency for some of their properties to change and the proteins themselves may be denatured when extracted by detergents. One of the most significant approaches to solve this problem is the use of styrene-maleic acid copolymers (SMAs), which offers detergent-free solubilization of embrane, which allows studies of membrane proteins to be done in very small systems. The main goal of this thesis is to examine the effects of these polymers on the interior of the lipid bilayer. With these, membrane proteins can be extracted from cell membranes while conserving a patch of near-native membrane around them. It has been suggested but not proven that proteins in nanodiscs reside in a hydrophobic environment that is identical to that found in the native cell membrane. Moreover, I also investigate the kinetics of membrane solubilization by SMA by using UV/visible spectrophotometer. In addition, I examine how lipid packing in the nanodiscs is affected by the presence of the polymers and how it depends on polymer composition by using SMA variants with different styrene-to-maleic acid ratios.

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29

Badot, Pierre-Marie. "Approche cellulaire du mécanisme du mouvement révolutif des tiges volubiles : Étude de quelques paramètres physico-chimiques." Besançon, 1987. http://www.theses.fr/1987BESA2032.

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Le mouvement révolutif serait la conséquence du déplacement circulaire d'une onde d'enrichissement en potassium qui induit avec un certain déphasage une onde de turgescence. Le mouvement serait donc le résultat d'un processus cellulaire marqué par un déséquilibre hydrique constamment entretenu

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30

Barcellos, Talita da Silva. "Eletrooxidação do ácido maleico utilizando diferentes composições de anodos dimensionalmente estáveis." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/59/59138/tde-11092009-110932/.

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Este projeto propôs a utilização de eletrodos de óxidos metálicos contendo RuO2 para realizar a eletrooxidacao do ácido maleico visando sua degradação total ou formação de produtos com menor grau de toxicidade. A oxidação de compostos fenólicos, clorados ou não, resultam em alguns produtos que interferem na mineralização completa das estruturas clorofenólicas, o ácido maleico, que é um dos principais intermediários obtidos depois da abertura do anel aromático. Os recobrimentos óxidos foram caracterizados por Microscopia Eletrônica de Varredura e Análise Dispersiva de Raios X. A caracterização eletroquímica por voltametria cíclica foi utilizada para determinação de potenciais de oxidação do acido maleico em função do eletrólito de suporte. As eletrólises foram realizadas a corrente controlada visando à melhor relação entre eficiência de corrente/degradação e melhoria no entendimento do mecanismo de oxidação. As análises quantitativas dos produtos da eletrólise foram feitas através de CLAE e a taxa de mineralização foi determinada pela quantidade de COT. Além destes dois métodos, também foram realizados testes de DQO e AOX. Os resultados mostraram que os métodos de preparação utilizados são apropriados, pois apresentaram estabilidade química, mecânica, eficiência na oxidação do ácido maleico e redução do carbono orgânico total.
This project proposed the use of metallic oxide electrodes containing RuO2 to perform the total degradation or formation of products with less toxicity. The oxidation of phenolic compounds, chlorinated or not, result in some products that interfere with complete mineralization of chlorophenol structures, the maleic acid, which is a important intermediate obtained after opening the aromatic ring. The coatings were characterized by scanning electron microscopy and X-ray dispersive analysis. The electrochemical characterization by cyclic voltammetry was used to determine the potential for the oxidation of maleic acid as a function of electrolyte support. The electrolyses were carried out at controlled current to the best ratio of efficiency of current/degration and improving the understanding of the mechanism of oxidation. The quantitative analysis of the electrolysis products were made by HPLC and the rate of mineralization was determined by the amount of TOC. Besides these two methods were also investigated COD and AOX. The results showed that the electrode preparation methods used are appropriate, showing chemical stability, mechanical efficiency in the oxidation of maleic acid and reduction of total organic carbon

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31

Šikyňová, Martina. "Funkcionalizace polypropylenu maleimidy." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-432952.

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Diploma thesis deals with preparation of polypropylene functionalized by maleimides, based on the reaction between maleic anhydride and amine. The overview of functionalization of polypropylene by maleic anhydride by reactive extrusion and routes for the synthesis and utilization of maleimides are contained in the theoretical part. Samples of maleimide-functionalized polypropylene were prepared by reactive extrusion using low molecular weight amines (aniline and 4-aminophenol) and hight molecular weight polyether monoamines. Functionalized polypropylene samples were prepared by several methods differing in the composition of the reaction mixture and performing a grafting reaction. Appropriate maleamic acids and maleimides were synthesized from low molecular weight amines and further used to functionalize the polypropylene. To characterize the samples, the degree of monomer conversion and melt flow index were determined and further analyses were performed by Fourier transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The synthesis of low molecular weight products was further monitored by thin layer chromatography and thermogravimetric analysis with evolved gas analysis.

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32

Teo, Alvin Chen Kuang. "Detergent-free approach to the studies of bacterial cell division membrane proteins using styrene maleic acid copolymer." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/101773/.

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Membrane proteins represent a subset of proteins embedded in or associated with the biological membrane. Despite accounting for 30% of the prokaryotic and eukaryotic proteomes and over 50% of current therapeutic targets, the structural and functional studies of membrane proteins still largely lag behind their soluble counterparts. This is predominantly due to the challenges in the isolation and purification of these proteins from their native mmembrane environment. Traditionally, detergents are employed for the extraction of membrane proteins from the native membrane, with subsequent solubilisation in mixed micelles. However, the surrounding lipids could be sequestered and lost during this process, which is potentially denaturing to the proteins. A novel method exploiting the styrene maleic acid (SMA) copolymer for membrane solubilisation (in the total absence of detergents) results in the generation of SMA/lipid particles (SMALPs) or ‘native nanodiscs’ of polymer-encapsulated membrane proteins together with their surrounding lipid moieties. Besides allowing the direct solubilisation of target membrane proteins from their native environment, analyses of native protein-lipid interactions and the characterisation of membrane lipidomes could be implemented, which may provide pivotal information to underpin the development of the next-generation antimicrobial agents. This detergent-free approach was successfully applied to the two cell division proteins, i.e. ZipA and FtsA and another integral membrane lipid phosphatase - PgpB from Escherichia coli. An analytically robust ‘SMALP lipidomics’ method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to elucidate the co-extracted membrane lipidomes of these proteins, resulting in the first comprehensive report of their respective native phospholipid compositions. Biophysical and biochemical characterisations were also conducted on PgpB in the context of SMALP and a detergent benchmark to facilitate the direct comparison between these two approaches for membrane protein studies.

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Kunimasa, Junichi. "Pharmacokinetics and pharmacological effect of recombinant human granulocyte colony-stimulating factor conjugated to poly (styrene-co-maleic acid) in rats." Kyoto University, 2001. http://hdl.handle.net/2433/150596.

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34

Maric, Hans-Michael [Verfasser], and Hermann [Akademischer Betreuer] Schindelin. "Molecular Basis of the Multivalent Glycine and γ-Aminobutyric Acid Type A Receptor Anchoring / Hans-Michael Maric. Betreuer: Hermann Schindelin." Würzburg : Universität Würzburg, 2012. http://d-nb.info/1107802466/34.

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Hassan, Anwar I. "Development of ¹⁹F NMR Methods for the Study of GlpG Rhomboid Protease in Detergents and Lipid Nanoparticle Systems." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/42521.

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Rhomboids are a family of intramembrane serine proteases that cleave transmembrane protein substrates within the lipid membrane. They are involved in a wide range of biological processes, including signal transduction, parasite invasion, bacterial quorum sensing and apoptosis. While previous X-ray crystal structures and functional studies have provided some detailed insights into the mechanism of intramembrane hydrolysis, it is still not clear how the transmembrane substrate can gain access into the active site from the lipid environment. While several modes of action have been suggested, one hypothesis proposes a lateral movement of the fifth transmembrane helix, causing a displacement that would allow transmembrane substrates to enter the rhomboid active site. A powerful method that has the potential to yield insights into rhomboid dynamics is solution NMR; however, the large size of rhomboid protease samples has complicated conventional methods typically used to assess protein structure and dynamics. ¹⁹F NMR could allow the study of rhomboid conformational dynamics by providing a simplified spectrum with high sensitivity to changes in local chemical environments. In this thesis various methods of ¹⁹F incorporation were evaluated for utility in studying rhomboid conformational dynamics, focusing on the GlpG rhomboid from E. coli. First, GlpG samples were prepared with ¹⁹F incorporated into tryptophan sidechains, and 1D ¹⁹F NMR spectra were acquired. While spectra with decent spectral dispersion were obtained, the assignment process was complicated by low signal-to-noise, and multiple changes in the spectrum introduced by the mutation. Chemoselective labelling of cysteine residues with probes containing a trifluoromethyl group was also investigated and found to give rise to well resolved ¹⁹F NMR spectra with promising characteristics. In addition, protocols for incorporation of trifluoromethyl-phenylalanine using unnatural amino acid incorporation at introduced amber codon sites were also explored, since one of the long-term goals of this work is to study ¹⁹F-labelled GlpG in its native lipid environment. For this purpose, some protocol development was also performed to introduce GlpG into lipid nanoparticles using styrene maleic acid co-block polymers. However, low expression yields of trifluoromethyl-phenylalanine-labelled GlpG and the large size of the lipid nanoparticles are not yet compatible with solution NMR. Nonetheless, this thesis lays the groundwork for further development of these samples to allow the future study of conformational exchange of GlpG in native lipid membranes.

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36

Reghizzi, Bruno. "Selective oxidation of furfural and 5-methylfurfural under green conditions." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13421/.

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Bio-renewable fuels and chemicals are becoming increasingly important as humans continue to deplete petroleum resources. An important aim for the future is to develop new processes from biomass and use it as a versatile feedstock because it is the largest carbon resources on earth. The increasing cost of fossil fuels and concerns about their environmental impact are accelerating the transition to a biomass-based economy. While fuel production from biomass has gained much attention, the use of renewable resources is also very important for the production of chemicals. Typically, chemical intermediates have a much higher value than fuels. These intermediates, traditionally derived from fossil fuels, can be further transformed into solvents, polymers, and specialty chemicals. The aim of this work is to investigate the catalytic transformation of furfural and 5-methyl furfural, two important intermediates obtained from biomass upgrading. It is more particular focused on their oxidation using green conditions and heterogeneous catalysts. In literature many processes for the catalytic oxidation of furfural are reported. In this process the highly desired product is maleic acid, but many other interesting products like furoic acid and furanone can be also obtained depending on the catalytic system used (and/or conditions). The reactivity of 5-methyli furfural is still instead quite unknown. The first part of the thesis screened different types of heterogeneous catalysts to produce selectively furoic acid or maleic acid from furfural and 5-methyl furoic acid from 5-methyl furfural. Very often this type of reactions hides several problems and specific conditions must be applied to improve furfural and 5-methyl furfural conversion, overall carbon balance, yield and selectivity to the desired products and this is was the aim of the second part of the study.

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37

Zhang, Shuo. "Physical properties and crystallization of theophylline co-crystals." Licentiate thesis, KTH, Transport Phenomena, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-13255.

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This work focuses on the physical properties and crystallization of theophyline co-crystals. Co-crystals of theophylline with oxalic acid, glutaric acid and maleic acid have been investigated.

The DSC curves of these co-crystals show that their first endothermic peaks are all lower than the melting temperature of theophylline. The decomposition temperature of theophylline – oxalic acid co-crystal is at about 230 °C, determined by DSC together with TGA. After decomposition, the remaining theophylline melts at about 279 °C, which is higher than the known melting temperature of theophylline, suggesting a structure difference, ie. a new polymorph may have been formed. The formation of hydrogen bonds in theophylline – oxalic acid co-crystal was investigated by FTIR. Changes of FTIR peaks around 3120 cm^-1 reflects the hydrogen bond of basic N of theophylline and hydroxyl H of oxalic acid. The solubility of theophylline – oxalic acid co-crystal and theophylline – glutaric acid co-crystal was determined in 4:1 chlroform – methanol and in pure chloroform respectively. At equilibrium with the solid theophylline – oxalic acid co-crystal, the theophylline concentration is only 60 % of the corresponding value for the pure solid theophylline. At equilibrium with the solid theophylline – glutaric acid co-crystal, the theophylline concentration is at least 5 times higher than the corresponding value for the pure solid theophylline. Two phases of theophylline were found during the solubility determination. In the chloroform – methanol mixture (4:1 in volume ratio) the solubility of the stable polymorph of theophylline is found to be about 14 % lower than that of the metastable phase. Various aspects of the phase diagram of theophylline – oxalic acid co-crystal was explored.

Theophylline – oxalic acid co-crystal has been successfully prepared via primary nucleation from a stoichiometric solution mixture of the two components in chloroform – methanol mixture. By slurry conversion crystallization, the co-crystal can be prepared in several solvents, and yield and productivity can be significantly increased. Theophylline – glutaric acid can be successfully prepared via both co-grinding of the two components and slow evaporation with seeding.

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38

Matláková, Jana. "Modifikace PLA reaktivní extruzí." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2012. http://www.nusl.cz/ntk/nusl-216866.

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Diplomová práce se zabývá roubováním maleinanhydridu a anhydridu kyseliny itakonové na kyselinu poly(mléčnou) (PLA). U modifikované kyseliny poly(mléčné) byla sledována závislost konverze monomerů na různých molárních poměrech monomer/iniciátor při teplotách 180°C a 200°C. Množství naroubovaného monomeru bylo stanovováno acidobazickou titrací a pomocí FT-IR spektroskopií. Vliv stupně naroubování na krystalinitu modifikované PLA byl zjišťován pomocí diferenční kompenzační kalorimetrie, DSC. Degradace PLA byla orientačně pozorována pomocí indexu toku taveniny, MFI.

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39

Goetz, Lee Ann. "Preparation and analysis of crosslinked lignocellulosic fibers and cellulose nanowhiskers with poly(methyl-vinyl ether co maleic acid) â " polyethylene glycol to create novel water absorbing materials." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45893.

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The search for cellulosic based products as a viable alternative for petroleum-based products was the impetus for covalently crosslinking lignocellulosic fibers and nanocellulose whiskers with poly(methyl vinyl ether) co maleic acid (PMVEMA) - polyethylene glycol (PEG). The lignocellulosics used were ECF bleached softwood (pine) and ECF bleached birch kraft pulp. This thesis also tests the hypothesis that water absorption and retention can be improved by grafting PMVEMA-PEG to the surface of ECF bleached kraft pulp hardwood and softwood fibers via microwave initiated crosslinking. The crosslinking of the PMVEMA to hardwood and softwood kraft ECF bleached pulp fibers resulted in enhanced water absorbing pulp fibers where the PMVEMA is grafted onto the surface of the fibers. The crosslinking was initiated both thermally and via microwave irradiation and the water absorption and water retention was measured as the percent of grafted PMVEMA. This was the first application of microwave crosslinking of pulp fibers with the goal of creating water absorbing pulp fibers. Ultimately, the water absorption values ranged from 28.70 g water per g dry crosslinked pulp fiber (g/g) to 230.10 g/g and the water retention values ranged from 26% to 71% of the water retained that was absorbed by the crosslinked pulp fibers. The microwave initiated crosslinked fibers had comparable results to the thermally crosslinked fibers with a decreased reaction time, from 6.50 min (thermal) to 1 min 45 sec (microwave). Cellulose nanowhiskers, crystalline rods of cellulose, have been investigated due to their unique properties, such as nanoscale dimensions, low density, high surface area, mechanical strength, and surface morphology and available surface chemistry. Prior to this study, the crosslinking of cellulose whiskers with the matrix via solution casting of liquid suspensions of whiskers and matrix had not been explored. The hypothesis to be investigated was that incorporating cellulosic whiskers with the PMVEMA-PEG matrix and crosslinking the whiskers with the matrix would yield films that demonstrate unique properties when compared to prior work of crosslinking of PMVEMA-PEG to macroscopic ECF bleached kraft pulp fibers. Solution cast composites of cellulose nanowhiskers-PMVEMA-PEG were crosslinked at 135 °C for 6.5 min and analyzed for crosslinking, thermal stability, strength and mechanical properties, whisker dispersion, and water absorption and uptake rates. The whisker-composites demonstrated unique properties upon crosslinking the whiskers with PMVEMA-PEG, especially the elongation at break and tensile strength upon conditioning of the final materials at various relative humidities. In addition, the whiskers improved the thermal stability of the PMVEMA-PEG matrix. This is significant as methods of improving processing thermal stability are key to developing new materials that utilize cellulose whiskers, PMVEMA, and PEG. This thesis addresses the hypothesis that cellulose nanowhiskers that are crosslinked with a matrix can create new whisker-matrix composites that behave differently after crosslinking.

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40

Nugroho, Robertus Wahyu Nayan. "Steric Stabilization of Polylactide particles achieved by Covalent 'grafting-from' with Hydrophilic Polymers." Licentiate thesis, KTH, Polymerteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122429.

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Despite numerous advantages of using particles in a wide range of applications, they have one drawback that is their tendency to agglomerate. One way to overcome this problem is to sterically stabilize the particles by introducing polymeric chains covalently attached to the surface. Surface modification by covalently attaching polymer chains to the particle surface can be achieved by e.g. a ‘grafting-from’ technique under UV irradiation. In this thesis, polylactide (PLA) particles were surface modified, under UV irradiation, with the hydrophilic monomers: acrylamide (AAm), acrylic acid (AA), and maleic anhydride (MAH). The developed ‘grafting-from’ technique was shown to be nondestructive method for surface modification of PLA particles of two different geometries. The change in surface chemistry of the PLA particles was confirmed by FTIR and XPS, indicating the success of the surface grafting technique. Force interaction between two surface grafted PLA substrates was measured by colloidal probe AFM in different salt concentrations. In order to understand the repulsive force, the AFM force profiles were compared to the DLVO theory and AdG model. Long range repulsive interactions were mainly observed when hydrophilic polymers were covalently attached to the surface of PLA particles, leading to steric interaction. Attractive force dominated the interaction when neat PLA particle was approaching each other, resulting in particle aggregation, even though short range repulsion was observed at small separation distance, i.e. approximately 10 nm. Attractive interaction was also observed when neat PLA was approaching to PAA-grafted PLA substrate. This attractive interaction was much greater than force interaction between two neat PLA substrates. The surface grafted particles can be used in biomedical application where secondary interactions are important to overcome particle agglomeration such as particle-based drug delivery.

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Anjos, Otavia Faria dos. "Exsudação de ácido málico e alongamento radicular de genótipos de milho tratados com níveis tóxicos de alumínio." Universidade Federal de Viçosa, 2007. http://locus.ufv.br/handle/123456789/4283.

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Made available in DSpace on 2015-03-26T13:36:32Z (GMT). No. of bitstreams: 1 texto completo.pdf: 233114 bytes, checksum: c512aebdda22870fd45ba41c414294f0 (MD5) Previous issue date: 2007-10-31
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Aluminum effects on malic acid exudation and root elongation were evaluated in two maize genotypes: UFVM 100 e UFVM 200, selected from a group of six genotypes developed by the Agronomy Department of the Federal University of Viçosa, Viçosa, MG, Brazil. Five days-old seedlings of the six genotypes were exposed to Al 50 µM in 0.4 mM CaCl2, pH 4.0, for 24 h and, based on growth inhibition of the main root, they were classified into two categories: a) Al sensitive (≥ 68% inhibition): UFVM 8 and UFVM 100; and b) Al tolerant (≤ 64% inhibition): UFVM 6, UFVM 7, UFVM 9 and UFVM 200. The genotypes: UFVM 100 and UFVM 200 were selected for the following experiments. Seedlings of both genotypes were treated with different Al concentrations and different time of exposition to the metal and then the Al effect on root elongation was evaluated. The elongation of the main root decreased with increasing Al concentration in both genotypes, especially in the UFVM 100 genotype. Differences between cultivar were higher at lower concentration but decreased as Al concentration was increased in the growth medium. Inhibition in the elongation of the main root was evident from the beginning of Al treatment and increased linearly with the time of exposition to Al. The UFVM 200 genotype always showed higher Al tolerance than the UFVM 100 genotype and the differences between them were bigger at Al concentration between 25 and 50 µM. Aluminum contents in leaves were always low in comparison with the roots, but the UFVM 200 genotype showed higher Al contents than the UFVM 100 genotype. In the roots Al contents increased with increasing Al concentration in the growth medium and they were always higher in the UFVM 100 genotype. The activity of the malate dehydrogenase (MDH) was higher in roots, but it increased with Al treatment only in leaves of the tolerant genotype. Malic acid exudation to the growth medium was observed in control plants of both genotypes. In Al-treated plants of both genotypes malic acid exudation increased with increasing Al concentration in the growth medium but UFVM 200 genotype always showed higher exudation at all Al concentrations. Maximum malic exudation occurred at estimated Al concentration of 133 and 197 µM for the genotypes UFVM 200 e UFVM 100, respectively. Although, both genotypes have exudated malic acid to the growth medium, in none of them the amount of malic acid was enough to detoxify the Al in the nutrient solution.
Os efeitos do alumínio sobre o alongamento radicular e a exsudação de ácido málico foram avaliados em dois genótipos de milho: UFVM 100 e UFVM 200, selecionados de um grupo de seis genótipos desenvolvidos pelo Departamento de Fitotecnia da Universidade Federal de Viçosa, Viçosa, MG, Brasil. Plântulas, com cinco dias de idade, dos seis genótipos foram expostas a Al 50 µM em solução de CaCl2 0,4 mM, por 24 horas e, baseado na inibição do alongamento radicular, foram classificados em duas categorias: a) sensíveis ao Al (≥ 68% de inibição): UFVM 8 e UFVM 100; e b) tolerantes ao Al (≤ 64% de inibição): UFVM 6, UFVM 7, UFVM 9 e UFVM 200. Os genótipos UFVM 100 e UFVM 200 foram selecionados para os demais experimentos. Plântulas dos dois genótipos foram expostas a diferentes concentrações de Al e diferentes tempos de exposição e, então, o efeito do Al sobre o alongamento da raiz principal foi avaliado. O alongamento da raiz principal decresceu com o incremento na concentração de Al nos dois genótipos, especialmente no genótipo UFVM 100. Diferenças entre os genótipos foram maiores em baixas concentrações de Al e decresceram à medida que a concentração de alumínio foi aumentando no meio de cultivo. Inibições no crescimento da raiz principal foram evidentes desde o início da aplicação do tratamento e aumentaram linearmente com o tempo de exposição ao Al. O genótipo UFVM 200 mostrou sempre maior tolerância ao Al que o genótipo UFVM 100, tendo as maiores diferenças entre eles ocorrido entre 25 e 50 µM de Al. Os teores de Al nas folhas foram sempre baixas em comparação aos teores nas raízes, mas o genótipo UFVM 200 apresentou teores mais elevados que o genótipo UFVM 100. Nas raízes, os teores de Al aumentaram com a elevação na concentração de Al na solução de cultivo e foram sempre mais elevados no genótipo UFVM 100. A atividade da enzima desidrogenase malato (MDH) foi maior nas raízes, mas só foi modificada pelo tratamento com Al nas folhas do genótipo tolerante. Exsudação de ácido málico para o meio de cultivo ocorreu nas plantas controle dos dois genótipos. A exposição das plantas ao Al resultou em aumento na exsudação de ácido málico para o meio de cultivo, tendo o genótipo UFVM 200 apresentado maior exsudação deste ácido em todas as concentrações de Al. A exsudação máxima de ácido málico ocorreu nas concentrações estimadas de Al de 133 e 197 µM para os genótipos UFVM 200 e UFVM 100, respectivamente. Embora, os dois genótipos tenham exsudado ácido málico para o meio de cultivo, em nenhum deles a quantidade de ácido málico foi suficiente para eliminar a toxidez do Al na solução nutritiva.

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42

Touré, Fodé Saliou. "L’appui du Canada au processus de gouvernance démocratique au Mali (2006 – 2012) - Motivations ambiguës et résultats mitigés." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35012.

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Cette thèse est une contribution à la réflexion du rôle dynamique du Canada dans le soutien international au développement démocratique. Elle dresse un bilan des actions menées, entre 2006 et 2012, par l’Agence canadienne de développement international (ACDI), principal organe d’aide du Canada, en appui à la gouvernance démocratique au Mali, pays de concentration de l’aide canadienne. Elle soutient que les motivations de la coopération canadienne au Mali sont ambiguës et que les résultats sont mitigés. Les progrès accomplis ces dernières années ont été fragilisés par les conséquences de la crise sécuritaire et politique de 2012 et la suspension de l’aide bilatérale canadienne a compromis l’évolution dynamique de ses projets. La démarche analytique combine une approche constructiviste critique avec une analyse inductive pour l’interprétation des motivations ambiguës et des résultats mitigés obtenus. L’étude a été conduite au moyen d'analyses documentaires et d'entretiens semi-directifs approfondis auprès d’une dizaine de personnes ressources.

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43

Paulenka, Igor. "Funkcionalizace polyolefinů roubováním." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-316409.

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The theoretical part of the diploma thesis is focused on the funcionalization of polyolefins in order to accelerate their degradation and to increase their carbon content from renewable resources with focus on hydroxyacids. The experimental part is focused on preparing samples and studying the properties of the polypropylene and polyethylene blends with the polylactide with different contents of the initiator and the maleic anhydride. Samples were evaluated by determining the degree of conversion maleic anhydride, differential scanning calorimetry, infrared spectroscopy, melt flow index and mechanical properties.

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44

Mubarok, Mahdi. "Valorization of beech wood through development of innovative and environmentally friendly chemical modification treatments." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0141.

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Dans cette étude, l’amélioration des propriétés physiques et de sa durabilité aux agents de dégradation biologique du hêtre européen (Fagus sylvatica) a été réalisée au moyen de différents traitements. Les premiers types de traitements sont basés sur l'imprégnation de dérivés vinyliques de glycérol ou de polyglycérol en tant qu'additif suivi d’une étape de modification thermique réalisée dans un réacteur ouvert (OHT) ou fermé (HPS). Le deuxième type de traitement repose sur la poly-estérification in situ du sorbitol et de l'acide citrique à différentes concentrations et températures de durcissement en système ouvert. Diverses propriétés de durabilité physique, chimique, mécanique et biologique des bois modifiés ont été évaluées. Les résultats montrent que certains traitements peuvent améliorer de manière significative les propriétés de durabilité physique et biologique du bois contre les agents de pourriture blanche, brune et molle et surtout vis-à-vis de l’attaque des termites comparativement au bois non traité ou modifié thermiquement uniquement
In this study, improvement of physical and biological durability properties of European beech (Fagus sylvatica) has been performed through different bulking impregnation treatments. The first modification was based on the impregnation of vinylic derivatives of glycerol or polyglycerol as additive followed with different thermal modification conditions in the opened system (OHT) or in the closed system (HPS). The second modification was based on the in-situ polyesterification of sorbitol and citric acid at different concentrations and curing temperatures in the opened system. Various physical, chemical, mechanical, and biological durability properties of the modified woods were evaluated, including certain properties during modification. The results have disclosed that certain treatments can improve significantly physical and biological durability properties of wood against decay (white rot, brown rot, and soft rot fungi) and termites attacks in comparison to untreated wood or thermally modified woods

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45

Metin, Onder. "Synthesis And Characterization Of Water Soluble Polymer Stabilized Transition Metal(0) Nanoclusters As Catalyst In Hydrogen Generation From The Hydrolysis Of Sodium Borohydride And Ammonia Borane." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612717/index.pdf.

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Metal nanoclusters exhibit unique properties which differ from their bulk materials, owing to the quantum size effects. For example, the catalytic activity of transition metal nanoclusters generally increases with decreasing particle size. However, nanoclusters tend to be fairly unstable with respect to the agglomerate into bulk metal in solution and thus special precautions have to be taken to avoid their aggregation or precipitation during the preparation of such nanoclusters in solution. In order to obtain stable nanoclusters dispersed in solution, a stabilizing agent is usually added into the reaction system. The stabilization of metal nanoclusters in solution can be achieved either by electrostatically by using charged ions such as acetate ion or sterically by long chain molecules such as polymers. Polymers are one of the most widely used steric stabilizers for the preparation of stable metal nanoclusters in solution. The use of polymers as stabilizer for the synthesis of transition metal nanoclusters provides advantegous regarding solubility, conductivity, thermal stability and reusability. The metal nanoclusters stabilized by polymers generally show higher catalytic activity, stability and optical properties. In this dissertation we report the preparation and characterization of water soluble polymer stabilized transition metal(0) (metal= Ni, Co and Ru) nanoclusters and their v catalysis in hydrogen generation from the hydrolysis of sodium borohydride (NaBH4) and ammonia borane (AB) which are the best candidates as chemical hydrogen storage materials for on-board applications. The water soluble polymer stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters were prepared by using two different facile methods
(i) the reduction of metal precursors by sodium borohydride in the presence poly(N-vinyl pyrrolidone) (PVP) in methanol solution after 1h reflux, (ii) the in situ generation during the hydrolysis of ammonia borane in the presence of poly(4-styrene sulfonicacid-co-maleic acid) (PSSA-co-MA). The characterization of both type of polymer stabilized transition metal(0) nanoclusters were done by using UV-Visible electronic absorption spectroscopy (UV-Vis), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and FT-IR techniques. The catalytic activity of PVP stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters was tested in the hydrolysis of NaBH4 and AB. The catalytic acitivity of PSSA-co-MA stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters was tested only in the hydrolysis of AB in which they were in situ generated. The kinetics of hydrogen generation from both hydrolysis reactions in the presence PVP or PSSA-co-MA stabilized nickel(0), cobalt(0) and ruthenium(0) nanoclusters were studied depending on the polymer to metal ratio, catalyst concentration, substrate concentration and temperature as well as the activation parameters (Arrhenius activation energy (Ea), activation enthalpy (

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46

陳一中. "Synthesis and Purification of Malic Acid." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/04270956877438013391.

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碩士
長庚大學
化學工程研究所
89
英文摘要 D,L-malic acid is utilized in great quantity as food additives, pH control agent, and raw material of alkyd polyester resins. The demand of D,L-malic acid is increasing with the increase of the beverage market. There is no any Corporation for production D,L-malic acid yet in Taiwan. But two companies of Excel Corp. and Grand Union Chemical Corp. can supply maleic anhdride,which is the raw material of malic acid. Open literature has shown that maleic acid or maleic anhydride reacts with water at 120~200℃ would produce malic acid, in which the product will also contain fumaric acid which is the isomer of maleic acid. Impurities contained in food-grade malic acid should be less than 0.05wt% for maleic acid and 1.0wt% for fumaric acid. It is very difficult to purify the malic acid to meet the specification of food grade. Some experinmenp disclosed that activated carbon can effectively remove fumaric, but maleic acid should be exchanged by ion exchange resin.Pore diffusivities of , and ( ) for maleic acid, fumaric acid and malic acid by activated carbon were regressed with the isothermal diffusion model of mixed adsorber system. The breakthrough curves of the mixture acid containing malic acid, maleic acid and fumaric acid were setted well with the dispersed plug flow-linear driving force model. This work will study the experiment of the synthesis reaction of malic with maleic acid and fumaric acid as reactants. The adsorption isotherms and kinetics of fumaric acid, maleic acid and malic acid with activated carbon will be studied both by experiment and mathematics modeling.

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47

劉建盛. "Synthesis and Kinetics Study of Malic acid." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/89784077695907102331.

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碩士
長庚大學
化工與材料工程研究所
92
Malic acid exists in various kinds of organism . Natural fruit such as apple,hawthorn, grape, and cherry has high content of malic acid . Malic acid has many aspects of characteristics：its sourness can stand longer , it can get rid of our thirst ,being tasty and refreshing , its quality stable , and with high solubility in the water. FDA of the United States announced in 1969 that malic acid is safety edible. Afterward, malic acid is widely applied to be the sources of the food, to foodstuff manufacturing process, to foodstuff additive industries, to tobacco producing process, to medical industry, commodity chemical industries and to chemical industries. It can be widely used in various kinds of application and the consumption is very huge. Malic acid has very good potential in the marketing development at present. Malic acid can be produced by the following: fermentation, chemical synthesise and extraction from plant and fruit. Chemical syn- thesise method is normally carried out by reacting maleic acid or maleic anhydride with water, or by reacting fumaric acid with water. The reaction output, besides the malic acid, contains maleic acid and fumaric acid. Commercial production of malic acid maybe uses both maleic acid and fumaic acid as the raw material. This study uses two different groups of raw material to synthesize malic acid. One is maleic acid reaction with water, the other is maleic acid and fumaric acid reaction with water. The object of this study is investigation of how to get more than 95% conversion and more than 60% yield based on the above raw material with in a batch-high-pressure reactor with different operation conditions. The concentration profiles would form the basis for study the reaction kinetics. mathematical analysis, we can obtain isotherm constant and diffusivity coefficient, and discuss the consistence between experimental results and perio- dical brakethrough curves.

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48

Faria, Marta Pastor Fernandes Arraios. "Catalytic Valorization of Malic Acid with Alternative Solvents." Master's thesis, 2017. http://hdl.handle.net/10362/26837.

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The main focus of this research project consisted on the catalytic hydrogenation of malic acid, using ionic liquids as solvents and in presence of supercritical CO2. The catalysts used in this project were ruthenium and palladium heterogeneous catalysts. Using the catalyst ruthenium (II) bis(2-methylallyl)(1,5-ciclooctadiene) in the presence of ionic liquids containing the NTf2 anion, at 120 bar of hydrogen and a final pressure of 180 bar (after the addition of supercritical CO2), gamma-butyrolactone, 4-ethoxy-4-oxobutanoic acid, diethyl succinate and diethyl 2-hydroxysuccinate were mainly formed and were identified by gas chromatography coupled with mass spectrometry (GC-MS). When the ionic liquid [Bmim]NTf2 was used it was possible to obtain the compounds gamma-butyrolactone with a selectivity of 23.4%. However, increasing the aliphatic chain of the IL cation to [C6mim] it was possible to increase selectivity of this compound up to 41.4%. Nevertheless, using a completely different IL like [Emim]OAc, the formation of such compound did not occur. The referred compound has a significant importance in biodiesel field, and it is generally used as a building block in the synthesis of polymers and plastics, and therefore it is a target of this project. Changing the catalyst to palladium 5% on alumina and using ionic liquids with the [Emim] cation and different anions, new reaction conditions were studied to understand the influence of IL and catalyst in the type of products. Hence, using only 60 bar of hydrogen and around 60 bar of supercritical CO2, compounds butane-1,4-diol, diethyl succinate and diethyl 2-hydroxysuccinate were mainly obtained. Interestingly, the ionic liquid [Emim]OAc favored the formation of 1-methylpyrrolidine-2,5-dione and 1-ethylpyrrolidine-2,5-dione with high selectivity (30-60%). Catalysts used in these reactions were recovered by filtration, and analyzed by transmission electronic microscopy (TEM) which allowed the measurement of particles diameters. With ruthenium catalyst, nanoparticles were formed with 1.5-2.5 nm diameter. Ionic liquids used in the hydrogenation of malic acid were recovered by liquid-liquid extraction with an immiscible solvent. Their purity was assessed by NMR experiments, and compared with spectra from original ILs. Generally, it is possible to conclude that recovered ionic liquids were effectively recovered in high level of purity. In summary, the goals of this project were successfully accomplished, proving the usefulness of supercritical fluids and ionic liquids in carboxylic acid hydrogenation.
O objetivo principal deste trabalho de investigação consistiu na hidrogenação catalítica do ácido málico, utilizando líquidos iónicos como solventes e na presença de CO2 supercrítico. Os catalisadores utilizados neste projeto foram catalisadores heterogéneos de ruténio e de paládio. Utilizando o catalisador bis(2-metilalilo)(1,5-ciclooctadieno) de ruténio (II), na presença de líquidos iónicos com o anião NTf2 em comum, a 120 bar de hidrogénio e uma pressão final de 180 bar (após a adição de CO2 supercrítico), foram obtidos maioritariamente os compostos gamma-butirolactona, ácido 4-etoxi-4-oxobutanóico, succinato de dietilo e 2-hidroxi-succinato de dietilo, identificados através de cromatografia gasosa acoplada à espetrometria de massa (GC-MS). Com o líquido iónico [Bmim]NTf2 foi possível obter o composto gamma-butirolactona com uma seletividade de 23.4%. Contudo, aumentando a cadeia alifática do catião para [C6mim] foi possível aumentar a seletividade do mesmo composto para 41.4%. Porém, utilizando um líquido iónico composto por um catião e um anião diferentes, nomeadamente o líquido iónico [Emim]OAc, não ocorreu a formação deste produto. Este composto tem uma importância significativa na área do biodiesel, sendo geralmente utilizado como building block na síntese de polímeros e plásticos e como tal, consiste num composto alvo deste projeto. Mudando para um catalisador de paládio, e utilizando líquidos iónicos com o catião [Emim] em comum e diferentes aniões, foram estudadas novas condições reacionais de forma a entender a influência tanto do líquido iónico como do catalisador no tipo de compostos obtidos. Assim, diminuindo a quantidade de hidrogénio para 60 bar e usando cerca de 60 bar de CO2 supercrítico foram obtidos maioritariamente os compostos butano-1,4-diol, succinato de dietilo e 2-hidroxisuccinato de dietilo. Curiosamente, em ambas as condições reacionais o líquido iónico [Emim]OAc favorece a formação dos compostos 1-metilpirrolidina-2,5-diona e 1-etilpirrolidina-2,5-diona com elevada seletividade (30-60%). Os catalisadores utilizados foram recuperados após as reações através de filtração, e foram sujeitos a análise por microscopia eletrónica de transmissão (TEM) a qual permitiu medir o diâmetro das partículas. No caso do catalisador de ruténio, formaram-se nanopartículas com um diâmetro de 1.5-2.5 nm. Os líquidos iónicos utilizados nas reações de hidrogenação do acido málico foram recuperados através de extração líquido-líquido com um solvente imiscível. A pureza destes foi avaliada através de experiências de ressonância magnética nuclear (NMR), tendo sido comparados os resultados com os espectros dos líquidos iónicos originais. De uma forma geral pode-se concluir que os líquidos iónicos foram recuperados com sucesso e com elevado grau de pureza. Em resumo, os objetivos deste projeto foram cumpridos, comprovando a utilidade de fluídos supercríticos e dos líquidos iónicos na hidrogenação catalítica de ácidos carboxílicos.

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49

Chang, Jung-Chieh, and 張榮傑. "Synthesis and analysis of citric acid and malic acid modified chitosan beads." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/50423696816153199547.

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碩士
明志科技大學
化學工程研究所
99
The chitosan-citrate (CC) and chitosan-malate (CM) beads, prepared by ionotropic cross-linking and freeze-drying method, were used for the adsorption of Cu(II) ion from aqueous solution. The characterization of CC and CM beads were investigated by means of IR, X-ray diffraction (XRD), thermogravimetric analysis (TGA), inductively coupled plasma optical emission spectrometry (ICP-OES). The equilibrium adsorption data of Cu(II) on the CC and CM beads were correlated well with by Langmuir isotherm model. The maximum adsorption capacity for adsorption of Cu(II) ion, has been calculated from Langmuir isothermal, were 238.0mg/g (CC) and 256.4mg/g (CM). The experiment data was provide better fit in pseudo-second order adsorption equation , indicating that the chemical adsorption is rate-limit step in the adsorption of Cu(II) ion onto adsorbent. The thermodynamic parameters such as enthalpy change(△H°), entropy change (△S°)and Gibbs free energy change(△G°) were computed and the results showed that the adsorption of Cu(II) ion onto CC and CM beads was spontaneous and endothermic in nature.

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50

高一辰. "Purification of Malic Acid with Basic Ion Exchange Resin." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/37404362650203289219.

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碩士
長庚大學
化學工程研究所
87
DL-malic acid is white crystal compound. The major uses of DL-malic acid are food additive and pH value controlling agent in textile industry. The general industrial process for production DL-malic acid is followed by reaction of maleic acid or maleic anhydride with water. The specification of food grade DL-malic acid from U.S. FDA shows that the concentration of maleic acid should be less than 0.05 wt%, and the concentration of fumaric acid should be less than 1.0 wt% in the DL-malic acid product. No any company in Taiwan produce DL-malic acid yet.This work is investigate the adsorption characteristics of DL-malic acid, maleic acid and fumaric acid on the strong basic ion exchange resin Dainion SA-20A. Adsorption isotherms and diffusivities are to be obtained in the batch mixing system. Experimental and mathematical model of ion exchange column will also be developed and verified. The ion exchange column is high selective adsorption of maleic acid. DL-malic acid and fumaric acid are not high selective adsorption in ion exchange column.

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