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Littérature scientifique sur le sujet « Physicochemical characterisations »

Auteur : Grafiati

Publié le 21 décembre 2024

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Articles de revues sur le sujet "Physicochemical characterisations"

Evangelista, Tereza Cristina Santos, Giordano Toscano Paganoto, Marco Cesar Cunegundes Guimarães et Josimar Ribeiro. « Raman Spectroscopy and Electrochemical Investigations of Pt Electrocatalyst Supported on Carbon Prepared through Plasma Pyrolysis of Natural Gas ». Journal of Spectroscopy 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/329730.

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Physicochemical and electrochemical characterisations of Pt-based electrocatalysts supported on carbon (Vulcan carbon, C1, and carbon produced by plasma pyrolysis of natural gas, C2) toward ethanol electrooxidation were investigated. The Pt20/C180and Pt20/C280electrocatalysts were prepared by thermal decomposition of polymeric precursors at 350°C. The electrochemical and physicochemical characterisations of the electrocatalysts were performed by means of X-ray diffraction (XRD), transmission electron microscope (TEM), Raman scattering, cyclic voltammetry, and chronoamperometry tests. The XRD results show that the Pt-based electrocatalysts present platinum metallic which is face-centered cubic structure. The results indicate that the Pt20/C180electrocatalyst has a smaller particle size (10.1–6.9 nm) compared with the Pt20/C280electrocatalyst; however, the Pt20/C280particle sizes are similar (12.8–10.4 nm) and almost independent of the reflection planes, which suggests that the Pt crystallites grow with a radial shape. Raman results reveal that both Vulcan carbon and plasma carbon are graphite-like materials consisting mostly of sp2carbon. Cyclic voltammetry and chronoamperometry data obtained in this study indicate that the deposition of Pt on plasma carbon increases its electrocatalytic activity toward ethanol oxidation reaction.

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Tokárová, Zita, et Anna Biathová. « Synthesis and structure-physicochemical properties relationship of thiophene-substituted bis(5,4-d)thiazoles ». Nova Biotechnologica et Chimica 17, n^o 2 (1 décembre 2018) : 193–200. http://dx.doi.org/10.2478/nbec-2018-0020.

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Abstract Substituted thiophene-2-carbaldehydes 1a-dwere utilized in the synthesis of symmetrically substituted thiazolo[5,4-d]thiazoles 3a-d. Bis(5,4-d)thiazoles with thiophene core at the termini are the most employed in the chemistry of materials but exhibit insufficient solubility in majority of organic solvents with notable impact on the low yields of products. Accordingly, the synthetic approach towards 2,5-dithiophen- 2-yl-thiazolo[5,4-d]thiazole (3a) and its substituted derivatives 3b-d is discussed under the various reaction conditions. Appropriate structural characterisations are included with emphasis on relationship between structure and physicochemical properties highlighting the UV-Vis and fluorescence.

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Alemu, Negese, Subramanian Balakrishnan et Baru Debtera. « Extraction and Characterisation of Avocado Seed Starch, and Its Blend with Enset Cellulosic ». Advances in Materials Science and Engineering 2022 (22 octobre 2022) : 1–10. http://dx.doi.org/10.1155/2022/9908295.

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Avocado seed starch was extracted to prepare a biodegradable plastic film with enset cellulosic reinforcement and glycerol plasticiser. The characterisations were made in detail. Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimeter (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), rheometer, and Rapid Visco Analyser (RVA) techniques were employed to characterise the physicochemical properties of avocado seed starch, enset cellulosic, and the blend. Starch and enset cellulosic extraction yields are 18.3 ± 0.02% and 67.5 ± 0.08%, respectively. As a result, avocado seed starch and enset cellulosic blend can be used as alternative raw materials to develop biodegradable plastics.

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Boulangé, Laurence, Estelle Bonin et Michel Saubot. « Physicochemical characterisations of the bitumen–aggregate interface to get a better understanding of stripping phenomena ». Road Materials and Pavement Design 14, n^o 2 (juin 2013) : 384–403. http://dx.doi.org/10.1080/14680629.2013.803494.

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De, Arnab, Bhaskar Das, Debmalya Mitra, Asish K. Sen et Amalesh Samanta. « Exploration of an arabinogalactan isolated from Odina wodier Roxb. : Physicochemical, compositional characterisations and functional attributes ». Polymers for Advanced Technologies 31, n^o 8 (25 mars 2020) : 1814–26. http://dx.doi.org/10.1002/pat.4908.

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Jaffar, Syafiqah Syazwani, Suryani Saallah, Mailin Misson, Shafiquzzaman Siddiquee, Jumardi Roslan et Wuled Lenggoro. « Green Synthesis of Flower-Like Carrageenan-Silver Nanoparticles and Elucidation of Its Physicochemical and Antibacterial Properties ». Molecules 28, n^o 2 (16 janvier 2023) : 907. http://dx.doi.org/10.3390/molecules28020907.

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Herein, we report the green synthesis of flower-like carrageenan-silver nanoparticles (c-AgNPs) through a facile hydrothermal reaction at 90 °C for 2 h. The reduction of silver nitrate (AgNO3) to c-AgNPs was evident by the colour change of the solution from colourless to dark brown and further confirmed by a UV-Vis surface plasmon resonance (SPR) peak at ~420 nm. The FTIR spectra showed that the abundance of functional groups present in the carrageenan were responsible for the reduction and stabilisation of the c-AgNPs. The XRD pattern confirmed the crystalline nature and face-centred cubic structure of the c-AgNPs, while the EDX analysis showed the presence of a high composition of elemental silver (85.87 wt%). Interestingly, the morphological characterisations by SEM and FE-SEM revealed the formation of flower-like c-AgNPs composed of intercrossed and random lamellar petals of approximately 50 nm in thickness. The growth mechanism of flower-like c-AgNPs were elucidated based on the TEM and AFM analyses. The c-AgNPs displayed promising antibacterial properties against E. coli and S. aureus, with zones of inhibition ranging from 8.0 ± 0.0 to 11.7 ± 0.6 mm and 7.3 ± 0.6 to 9.7 ± 0.6 mm, respectively, as the concentration of c-AgNPs increased from 0.1 to 4 mg/mL.

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Bai, Dorottya, Zsuzsanna Schelz, Dóra Erdős, Anna K. Kis, Viktória Nagy, István Zupkó, György T. Balogh et Zsolt Szakonyi. « Stereoselective Synthesis and Antiproliferative Activities of Tetrafunctional Diterpene Steviol Derivatives ». International Journal of Molecular Sciences 24, n^o 2 (6 janvier 2023) : 1121. http://dx.doi.org/10.3390/ijms24021121.

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A new family of diterpene-type aminotriol derivatives has been synthesised from stevioside in a stereoselective manner. The key intermediate spiro-epoxide was prepared through the methyl ester of the allilyc diol derived from steviol. The oxirane ring was opened with primary and secondary amines, providing a versatile library of aminotriols. The corresponding primary aminotriol was formed by palladium-catalysed hydrogenation, and an N,O-heterocyclic compound was synthesised in a regioselective reaction. All new compounds were characterised by 1D- and 2D-NMR techniques and HRMS measurements. In our in vitro investigations, we found that the aromatic N-substituted derivatives exhibited high inhibition of cell growth on human cancer cell lines (HeLa, SiHa, A2780, MCF-7 and MDA-MB-231). The antiproliferative activities were assayed by the MTT method. Furthermore, the introduction of an additional hydroxy group slightly increased the biological activity. The drug-likeness of the compounds was assessed by in silico and experimental physicochemical characterisations, completed by kinetic aqueous solubility and in vitro intestinal-specific parallel artificial membrane permeability assay (PAMPA-GI) measurements.

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Ting, Chao Wen, Naji Arafat Mahat, Aida Rasyidah Azman, Nor Wajihan Muda et Nurazira Anuar. « Performance of the Nanobio-Based Reagent for Visualising Wet Fingerprints Exposed to Different Levels of Water Salinity ». Journal of Clinical and Health Sciences 6, n^o 1(Special) (30 juin 2021) : 32. http://dx.doi.org/10.24191/jchs.v6i1(special).13169.

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Introduction: Recovery of evidence such as murder weapons in waterways has been commonly reported. However, visualising latent fingerprints on the immersed substrates may prove challenging due to its obliteration by physicochemical parameters (e.g. pH, temperature, salinity) as well as the mechanical effect of water. Although the use of Small Particle Reagent (SPR) for visualising latent fingerprints on wet non-porous substrates has been suggested, it contains molybdenum and titanium that are toxic, and their utilisation must be reduced. Furthermore, no study verifies the chemical and/or physical interaction between SPR and the lipid constituents of wet latent fingerprints that leads to the visualisation of ridge details. Methods: The SPR and newly developed nanobio based reagent (NBR) i.e. Candida rugosa lipase-multiwalled carbon nanotubes (CRL-MWCNTs) were used for visualising latent fingerprints on glass slides immersed in water with salinitylevels representing those of estuary and swimming pool for up to 15 days. Results: It was observed that the quality of the visualised fingerprints using NBR was comparable with that of SPR. Characterisations via instrument and bioinformatics analyses have also verified the incorporation of CRL onto MWCNTs and the chemical interaction between NBR and lipid constituents of wet latent fingerprints. Conclusions: Therefore, the newly developed NBR may prove a promising relatively greener alternative for substituting SPR for visualising latent fingerprints on glass slides immersed in different levels of water salinity.

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Asma, Remil, Taghouti Mona, Benali Mohammed et Belbraouet Slimane. « Physicochemical Analysis, Electrophoretic Characterization and Verifica-tion of the Protein Fractions Responsible for Celiac Disease of Wheat Varieties Imported and Grown in Western Algeria ». South Asian Journal of Experimental Biology 7, n^o 3 (8 mars 2018) : 113–21. http://dx.doi.org/10.38150/sajeb.7(3).p113-121.

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Celiac disease is an inflammatory enteropathy induced by ingestion of wheat proteins. This study aims to verify the protein quality of wheat varieties that are either grown in or imported into Western Algeria, by carrying out physi-cochemical and electrophoretic characterisations of the gluten proteins. We carry out physicochemical analysis of thirty-four samples of durum and bread wheat, with regard to gluten proteins. The quality of gluten was ap-preciated by Zeleny volume of bread wheat and the SDS sedimentation test for durum wheat. Meanwhile, we also characterized glutenins and gliadins into thirteen cereal varieties by monodimensional electrophoresis on SDS-PAGE and Acid-PAGE respectively. The results showed that gluten levels ranges varied from 26.82±3.99% to 56.1±1.43%. The values of the total pro-tein content had the range of 11.35±0.42% to 20.57±0.98%. The varieties studied had Zeleny values between 7.79±1.45 mL to 40.07±2.96 mL for bread wheat, and the SDS sedimentation volume ranged from 24.5±0.70 mL to 51.25±2.47 mL for durum varieties. The analysis of the glutenin and gliadin composition of the wheat varieties by electrophoresis showed the existence of α- and ω-gliadins subunits, responsible for celiac disease. Furthermore, the results revealed the presence of gliadin subunits "γ-45" and glutenins "GS-LMW Type2" related to the good quality of gluten in some varieties of wheat. As a result, we can conclude that the wheat consumed in Western Algeria has a good quality of storage proteins. Therefore, it is far from being responsible for the decrease of celiac disease in this region.

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Hamman, Naasika, Poornima Ramburrun et Admire Dube. « Selenium Nanoparticle Activity against S. mutans Biofilms as a Potential Treatment Alternative for Periodontitis ». Pharmaceutics 16, n^o 4 (25 mars 2024) : 450. http://dx.doi.org/10.3390/pharmaceutics16040450.

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The disruption of periodontal biofilms and prevailing antimicrobial resistance issues continue to pose a great challenge to the treatment of periodontitis. Here, we report on selenium nanoparticles (SeNPs) as a treatment alternative for periodontitis by determining their antibiofilm activity against S. mutans biofilms and the potential role of particle size in disrupting biofilms. SeNPs were synthesised via a reduction reaction. Various physicochemical characterisations were conducted on the NPs, including size and shape. The microbroth dilution method was used to conduct the biofilm and antibiofilm assay against S. mutans, which was analysed by absorbance. SeNPs displayed hydrodynamic sizes as low as 46 ± 4 nm at a volume ratio of 1:5 (sodium selenite/ascorbic acid) with good monodispersity and stability. Hydrodynamic sizes of SeNPs after resuspension in tryptic soy broth supplemented with 2.5% sucrose (TSB + 2.5% suc.) and incubated at 37 °C for 24 h, ranged from 112 to 263 nm, while the zeta potential values increased to greater than −11 mV. The biofilm assay indicated that S. mutans are weakly adherent, bordering on moderately adherent biofilm producers. The minimum biofilm inhibitory concentration (MBIC) was identified at 500 µg/mL. At a 1000 µg/mL concentration, SeNPs were able to inhibit S. mutan biofilms up to 99.87 ± 2.41% at a volume ratio of 1:1. No correlation was found between antibiofilm activity and particle size; however, antibiofilm activity was proven to be concentration-dependant. SeNPs demonstrate antibiofilm activity and may be useful for further development in treating periodontitis.

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Thèses sur le sujet "Physicochemical characterisations"

Andrews, G. P. « Physicochemical characterisations of novel pharmaceutical polymer gel networks ». Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397846.

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Hadrane, Bachchar. « Vanadates de métaux de transition à feuillets kagomé : effets de la microstructure et des substitutions cationiques sur les propriétés structurales, vibrationnelles, optiques et magnétiques ». Electronic Thesis or Diss., Nantes Université, 2024. http://www.theses.fr/2024NANU4029.

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Cette thèse explore les effets de la microstructure et des substitutions cationiques sur les propriétés structurales, vibrationnelles, optiques et magnétiques de matériaux vanadates à feuillets Kagomé de cobalt et de zinc, dont les structures cristallines sont similaires à celles de minéraux (karpenkoite, martyite et vesignieite). La structure cristalline du pyrovanadate microstructuré Co3V2O7(OH)2·nH2O, préparé via la voie hydrothermale est résolue. Ses propriétés physicochimiques et magnétiques sont étudiées et comparées à celles reportées dans la littérature. L’effet de la substitution des ions Co2+ haut-spin par des ions Zn2+ est analysé pour une nouvelle solution solide microstructurée (Co1-xZnx)3V2O7(OH)2·wH2O. Les essais de synthèse du matériau Co3V2O7(OH)2·nH2O nanostructuré par coprécipitation à pression ambiante conduisent à un nouveau pyrovanadate microstructuré de formulation approchée NH4Co2.5V2O7(OH)2·H2O. Par ailleurs, l’orthovanadate BaCo3(VO4)2(OH)2 microstructuré est obtenu en utilisant Co3V2O7(OH)2·nH2O comme précurseur et ses propriétés sont comparées à celles d’échantillons nanostructurés récemment obtenus. Une telle comparaison est également réalisée pour le nouvel orthovanadate isostructural BaZn3(VO4)2(OH)2, préparé sous formes micro- et nanocristallisée. L’effet de la substitution cationique Co/Zn est étudié pour une nouvelle solution solide microstructurée Ba(Co1-xZnx)3(VO4)2(OH)2 et pour des échantillons nanostructurés de compositions similaires. Ce travail ouvre des possibilités d’études d’autres solutions solides analogues, comme Ba(Co1-xNix)3(VO4)2(OH)2
This thesis explores the effects of microstructure and cationic substitutions on the structural, vibrational, optical, and magnetic properties of cobalt or zinc Kagome layered vanadate materials, whose crystalline structures are similar to those of minerals (karpenkoite, martyite, and vesignieite). The crystalline structure of the microstructured pyrovanadate Co3V2O7(OH)2·nH2O , prepared by the hydrothermal route, was solved. Its physicochemical and magnetic properties were studied and compared with those reported in the literature. The effect of the substitution of Zn2+ ions for high-spin Co2+ ions is analysed for a new microstructured solid solution (Co1-xZnx)3V2O7(OH)2·wH2O. Synthesis attempts of the nanostructured Co3V2O7(OH)2·nH2O material led to a new microstructured pyrovanadate with an approximate formula NH4Co2.5V2O7(OH)2·H2O. In addition, the microstructured orthovanadate BaCo3(VO4)2(OH)2 is obtained using Co3V2O7(OH)2·nH2O as a precursor and its properties are compared with those of recently obtained nanostructured samples. Such a comparison is also carried out for the new isostructural orthovanadate BaZn3(VO4)2(OH)2, prepared in micro- and nanocrystallised forms. The effect of Co/Zn cationic substitution is studied for a new microstructured solid solution Ba(Co1-xZnx)3(VO4)2(OH)2 and for nanostructured samples of similar compositions. This work opens up the possibility of studying other analogous solid solutions, such as Ba(Co1-xNix)3(VO4)2(OH)2

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Trainor, D. M. « Physicochemical characterisation of cystic fibrosis sputum ». Thesis, Queen's University Belfast, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.398172.

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Griffith, Vivienne Jean. « Physicochemical characterisation of cyclodextrin-drug complexes ». Doctoral thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/25979.

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The cyclodextrins and their derivatives are finding increasing application in the pharmaceutical industry as carrier molecules for many drugs, as complexation can result in improved physical characteristics such as increased aqueous solubility and dissolution rates. The aim of this work was to prepare solid cyclodextrin complexes with selected drugs which have already been shown to interact with cyclodextrins in solution and ultimately to grow crystals of these inclusion complexes of sufficient quality for single crystal X-ray structure determination. The designated drugs included an antibacterial, sulfathiazole; three non-steroidal anti-inflammatory drugs (NSAIDs), (S)-naproxen and the sodium salts of diclofenac and meclofenamic acid; and (L)-menthol, a compound used in many pharmaceutical preparations. The chosen host molecules were ,β-cyclodextrin, γ-cyclodextrin, heptakis(2,6-di-O-methyl)-, β-cyclodextrin (DIMEB) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TRIMEB). The unit cell parameters of thirteen cyclodextrin-drug complexes and of TRIMEB monohydrate were determined by X-ray photography and the cry tal structures of six of these complexes and of TRIMEB monohydrate were solved. The water content of the complexes was established by thermogravimetric analysis and the host:guest stoichiometries of those complexes whose crystal structures were not solved were determined by UV spectrophotometry or, in one case, by a combination of NMR and thermogravimetric analysis. The complexes were also characterised by differential scanning calorimetry. Hot stage microscopy was a useful method for initial testing for the formation of inclusion complexes of the native cyclodextrins, since their behaviour on heating differs markedly from that of the relevant host alone. The events observed could be correlated with the thermal analyses of the complexes. Complexes which contained alkali metal cations appeared to retain water molecules of crystallisation to higher temperatures, on average, than those which did not. XRD patterns were calculated from the crystal structures which were solved and matched the experimental patterns of the prepared samples well. The calculated patterns serve as the best references for establishing the identity and purity of prepared complexes. Host-guest interactions included hydrogen bonding, van der Waals contacts and hydrophobic interactions. Guest molecules maintained similar conformations on the whole as those observed in other crystal structures containing these particular guests. Conformations of the hosts were akin to those found in known crystal structures, except in TRIMEB monohydrate, where the TRIMEB conformation was distorted to a remarkable extent even in comparison with the distorted conformations observed in its complexes. In addition, one of the methylglucose residues is present in the ¹C₄ inverted chair conformation which has not been observed before in the cyclodextrins or their complexes in the solid state. The invariable occurrence in the TRIMEB host of C(6Gn)-H···0(5Gn-1) hydrogen bonds noted in this study is partly responsible for the uniformity in the conformation of TRIMEB in its complexes. The packing arrangement found in the diclofenac sodium-β-CD complex is unique and is the first example of a β-CD complex crystallising in the hexagonal crystal system. The inclusion by β-CD of meclofenamate sodium (a structural isomer of diclofenac sodium) is similar to that of diclofenac sodium, but the packing arrangement is different and while unique for a complex of unsubstituted β-CD, resembles the packing arrangement found in most of the known TRIMEB complexes.

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Badruddin, Ahmad Fasihuddin. « Physicochemical characterisation and properties of sago starch ». Thesis, University of Salford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265740.

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Pena, Marcos Miguel Gonzalez. « Comparative physicochemical characterisation of thermally modified wood ». Thesis, Bangor University, 2007. https://research.bangor.ac.uk/portal/en/theses/comparative-physicochemical-characterisation-of-thermally-modified-wood(544e97d3-72ad-444e-9ebc-4a5076663cd9).html.

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Small matched samples of beech, Scots pine and Norway spruce woods were heattreated to twenty schedules, at temperatures of 190, 210, 230 and 245°C for heating periods of 0.3, 1, 4, 8 and 16 h. Following thermal modification, physical changes and chemical composition in thermally modified wood (TMW) were analysed and compared to the characteristics of untreated materials. Most of the analysis were carried out using the heat-induced weight loss values (WL, %) as the independ~nt variable to make the comparisons. Average treatment WL values ranged from 0.3 to 27.0, from 0.6 to 21.5, and from 1.0 to 26.7 for beech, pine, and spruce samples respectively. A major finding of this research was that each characteristic changed following the same profile in the three wood species for all properties studied. Save for hardness in beech, the magnitude and rate of change of each property was often found not to be significantly different between species when relative-to-control values in function ofthe WL were compared. The results show that the gravimetric and dimensional changes in the transverse plane are mainly due to chemical breakdown of wood hemicelluloses. On the other hand, the readiness ofTMW to dimensional changes and moisture uptake below the FSP was of a much lower concern than in raw wood. Similarly, several mechanical properties were found to be little affected by heat exposure at treatment levels likely to be achieved industrially. Among these were compression strengths parallel and perpendicular to the axis in the tangential direction, and the axial modulus of elasticity in bending (MOE). Other mechanical strength parameters (e.g. shear strength, hardness and the modulus of rupture in bending) were reduced at almost any given treatment schedule, but the rate of reduction was mild. It is contended that design practices could make up for the strength loss incurred by the treatment for these properties. On the other hand, parameters related to the energy required to produce failure and also impact strength were greatly diminished at low levels of modification. This may restrict the use of TMW where unpredictable sudden loads may occur. Properties at the limit of proportionality were found to be less reduced than the same property at maximum load. Mechanical properties more affected by heat were found to be those more intimately related to the chemical integrity of the wood material and/or the structural configuration of wood polymers in the cell wall substance, whilst compression strength and hardness were more related to wood density. MOE was proposed to be more dependent of cellulose, microfibril angle and wood density, all of these little altered by wood heating. Lastly, a description of the colour changes in the test samples was undertaken using image analysis and qualitatively by infrared spectroscopy. It was determined that colour changes in wood were caused mainly by changes in the lignin. The major input of this work to the state of the art is given by modelling the properties studied using various linear, non-linear and multivariate methods. Properties in TMW were estimated from gravimetric, colour and moisture-related parameters. Solid-state mid-infrared spectra data, treatment parameters and interrelationship between variables were also explored. It is concluded that all changes in small heated samples of wood are amenable to be estimated efficiently in multiple ways, using cost-effective indicators. Remarkably encouraging results for the prediction of physical properties were found for models using colour parameters or by the analysis of the infrared spectra data. Whilst descriptions of the heat-induced changes in wood exist, prediction studies are fairly scarce and not comprehensive. This part of the study is thus very timely, giving the current requirements of quality control and assurance of TMW at the industrial stage. The relevance of these fmdings to property prediction in larger wood members would depend on the property considered; safety factors will probably be needed for some forms ofwood strength in larger heated materials.

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Stone, Lisa Ann. « Physicochemical characterisation of disease associated abnormal prion proteins ». Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1446127/.

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The central feature of prion disease is the conversion of normal host-encoded cellular prion protein, PrPc, to an abnormal isoform, PrP. PrP80 appears to be the principal, if not the sole, component of infectious prions. Prion strain diversity seems to be encoded within PrP itself through a combination of PrP conformation, glycosylation and possibly other, as yet, unidentified post-translational modifications. Efficient purification of PrP will facilitate detailed chemical characterisation and investigation of conformations or assembly states required for prion infectivity. Purification of denatured PrP has been achieved through enrichment from brain homogenate using selective precipitation followed by chemical and thermal denaturation and isolation by immunoafTinity chromatography. These methods have isolated PrP from rodent prion strains with a yield of 50 % and purity of > 90 % of total protein and for the first time permit isolation of full length denatured PrPSc facilitating comprehensive structural analysis. Purified denatured PrP is expected to have all the covalent post-translational modifications that may be required for prion infectivity. In attempts to reconstitute prion infectivity, denatured PrP was refolded under different solvent conditions and assessed for changes in solubility, resistance to proteolytic digestion and infectivity in bioassay. Although distinct changes in the physicochemical properties of PrP were observed, to-date no evidence for reconstitution of prion infectivity has been found. In the course of these studies, it was discovered that Cu2f ions inhibit proteinase K activity and a detailed kinetic description of this inhibition was obtained. The lack of prion infectivity seen in refolded preparations of denatured PrP suggests a requirement for other as yet unidentified co-factors. The identity of PrP interacting proteins was investigated during the purification of PrP under differential extraction conditions in which prion infectivity was observed using an in vitro assay. Proteinase K digestion gave a change in prion infectivity implying that a correlation with the removal of a protease sensitive component occurred. Continuation of these studies may facilitate the identification of co-factors required for specific prion infectivity.

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Ngilirabanga, Jean Baptiste. « A supramolecular derivatised study of BIS(Adamantan-1- Aminium) carbonate ». University of the Western Cape, 2014. http://hdl.handle.net/11394/4188.

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Magister Pharmaceuticae - MPharm
In this study, new solid supramolecular derivatised forms of bis(adamantine-1-aminium) carbonate (ADTCO3) were prepared. ADTCO3 is a derivative of amantadine used for Parkinson’s disease and has antiviral properties against influenza-A, dengue fever and pharmacological activity towards Parkinson’s disease. The new forms prepared were polymorphic and co-crystal forms of ADTCO3. Polymorphism is a phenomenon where the ability of a substance to exist in two or more crystalline forms occurs when crystallised under different conditions and co-crystallization is the process of formation of multicomponent crystals of a drug substance. New solid forms often display different mechanical, physicochemical and thermal properties that can remarkably influence the bioavailability, hygroscopicity and stability of active pharmaceutical ingredients (APIs). For the formation of polymorphs of ADTCO3, techniques such as dry grinding, solvent-drop grinding, co-precipitation, sublimation and vapour diffusion were applied. For the development of co-crystals and/or complex formation, ADTCO3 was treated in combination with ten selected co-formers viz; benzoic acid, 4-hydroxybenzoic acid, cinnamic acid, 4-hydroxycinnamic acid, succinic acid, tartaric acid, salicylic acid, L-glutamic acid, citric acid monohydrate and L-glutaric acid using similar techniques as applied in the polymorphism study. The first four co-formers were selected for their potential biological activity and the latter six were selected for their generally regarded as safe (GRAS) status. All products were isolated and characterized using different analytical techniques to assess the thermal behaviour of the products by hot stage microscopy (HSM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). FTIR spectroscopy and proton-nuclear magnetic resonance (1HNMR) were used to identify and determine the purity of the parent compounds and the modified forms. X-ray powder diffraction was used to determine the formation of a new phase and single crystal X-ray diffraction was applied at the initial stages to identify ADTCO3 by its unit cell parameters. Furthermore, the Cambridge Structural Database (CSD) and other resources were used to generate information on the molecular structures of all elucidated parent compounds, their polymorphs and reported co-crystals. Four different polymorphic forms of ADTCO3 were identified (viz. ADTCO3 Forms I to IV) and sixteen co-crystals (viz. ADTCO3BA1 to ADTCO3BA5, ADTCO3HBA, ADTCO3CIN, ADTCO3HCIN, ADTCO3SUC, ADTCO3LTTA, ADTCO3SA, ADTCO3CA, ADTCO3GLA, ADTCO3GA) were synthesised. Of the sixteen co-crystals 5 were identified as ADTCO3BA “salt” co-crystal polymorphic forms and 2 as ADTCO3SUC co-crystal polymorphic forms. Two solvated “salt” co-crystal forms were also identified, namely; ADTCO3GLA and ADTCO3LTTA. ADTCO3GLA had a mass loss of 10.3% (n = 2.4) and ADTCO3LTTA had a mass loss of 5.25% (n = 0.86). Finally, the rest of the co-crystals ADTCO3HBA, ADTCO3CIN, ADTCO3HCIN, ADTCO3SA, ADTCO3CA and ADTCO3GA all crystallised as “salt” co-crystals.

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Fisk, Ian. « Physicochemical characterisation of sunflower seed oil bodies ex-vivo ». Thesis, University of Nottingham, 2007. http://eprints.nottingham.ac.uk/13575/.

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Oilseeds store energy as triacylglycerides during periods of dormancy in preparation for germination and the early stages of development. The triacylglyceride is stored in discrete organelles termed oil bodies. Oil bodies are formed during the synthesis of neutral lipids within the bilayer of cellular endoplasmic reticulum (ER); as lipid is synthesised it forms droplets of oil that swell distending the ER membrane and at a critical diameter separate from the ER by vesiculation forming independent organelles. These organelles are structurally stabilised by a phospholipid monolayer originating from the ER and the addition of highly amphiphilic oleosin proteins. Oil bodies have been shown previously to be extremely stable organelles that can be easily extracted and purified from oilseeds; our aim was to develop an understanding of the physical and chemical properties of sunflower oil bodies ex-vivo prior to their subsequent use in commercial products. Several novel findings were elucidated through this work: oil body phytochemical composition, their physical and oxidative stability and their ability to store and deliver flavour compounds. It was hypothesised that tocopherol is tightly associated with sunflower oil bodies. This was tested by recovering oil bodies from sunflower seed and washing them to remove extraneous proteins and associated phenolic compounds. Tocopherol remained with washed oil bodies (392 mg tocopherol.kg-1 oil body oil) and this population of tocopherol represented 38% of the total seed tocopherol. It was hypothesised that this high tocopherol concentration and its intrinsic association to oil body structures would contribute to an increased level of oxidative stability. Sunflower seed lipids were significantly more resistant to thermally induced oxidation when stabilised in oil body suspensions compared to sunflower oil emulsions stabilised by a range of commercial emulsifiers (sodium dodecyl sulfate, polyoxyethylenesorbitan monolaurate (tween 20) and dodecyltrimethylammonium bromide). Oxidative stability was assessed through lipid hydroperoxide concentration and the concentration of headspace hexanal. Maximum lipid hydroperoxide concentration in surfactant stabilised emulsions after 8 days at 45oC ranged between 26 and 333 mmol lipid hydroperoxide.kg-1 oil whereas lipid hydroperoxide concentrations in oil body suspensions did not exceed 12 mmol lipid hydroperoxide.kg-1 oil. In addition there was no development in oxidative rancidity over the 8 day storage trial of oil bodies stored at 5oC. The composition of phospholipids in a range of oil body preparations was assessed; purified oil bodies contained principally phosphatidylcholine (91%) and a smaller fraction of phosphatidylethanolamine (9%). Less purified preparations contained other phospholipid species; the presence of which was explained by contamination with either non-intrinsic cellular phospholipids or phospholipase D that catalysed the breakdown of phospholipids to phosphatidic acid. Mechanisms and the extent of oil body physical stability were assessed using charge analysis and resistance of oil body preparations to changes in temperature and pH. Oil bodies are stabilised by a combination of steric hindrance and electrostatic repulsion provided by the surface proteins and phospholipids. Oil bodies had a zeta potential of -30mV at neutral pH and the surface charge was pH dependant with an apparent isoelectric point of between pH3 and pH6 was calculated from electrophoretic mobility, streaming potential and creaming stability measurements. Purified oil bodies were physically stable to thermal stresses up to 45oC for 2 days, although less purified preparations lost structural integrity at temperatures above 25oC. When assessed for their ability to delivery flavour molecules, oil bodies had comparable bulk phase properties to artificial emulsions stabilised by tween 20. Oil bodies did show a greater rate of flavour delivery during headspace dilution, when compared with the model artificial emulsions, suggesting commercial benefits may be gained through the incorporation of oil bodies into commercial emulsions. The key findings of this work are that oil bodies are extremely stable organelles that are resistant to thermal stress and physical processing. When lipid is stored within oil bodies it has greater resistance to the onset of lipid oxidation which may be explained by the intrinsic association of phospholipids, proteins and phytochemicals (vitamin E).

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Wood, David. « Physicochemical characterisation of pluronic block copolymers in aqueous solutions ». Thesis, King's College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441991.

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Livres sur le sujet "Physicochemical characterisations"

Ahmad, Fasihuddin Badruddin. Physicochemical characterisation of alginates. Salford : University of Salford, 1987.

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Protozanova, Ekaterina. Physicochemical characterisation of multistranded DNA assemblies--DNA frayed wires. 2000.

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Chapitres de livres sur le sujet "Physicochemical characterisations"

Mulloy, Barbara. « Structure and Physicochemical Characterisation of Heparin ». Dans Heparin - A Century of Progress, 77–98. Berlin, Heidelberg : Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-23056-1_5.

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Park, Su Hyeon, Thanh Huyen Phan, Jeung Eun Kim et Wojciech Chrzanowski. « CHAPTER 3. Physicochemical Characterisation of Extracellular Vesicles ». Dans Biomaterials Science Series, 45–75. Cambridge : Royal Society of Chemistry, 2021. http://dx.doi.org/10.1039/9781839164552-00045.

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Ahmad, Fasihuddin B., Siraj Omar et Peter A. Williams. « Physicochemical Characterisation of Alginate from Malaysian Brown Seaweeds ». Dans Food Hydrocolloids, 187–92. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2486-1_28.

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Concha-Riedel, Jose, et Susana Lopez-Querol. « Unsaturated Geomechanical and Physicochemical Characterisation of Soils Used for Adobe Blocks ». Dans Lecture Notes in Civil Engineering, 433–40. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-20172-1_42.

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Lingard, Justin J. N., Barbara J. Brooks, Sarah J. Norris, Ian M. Brooks et M. H. Smith. « Physicochemical Characterisation of Marine Boundary Layer Aerosol Particles during the Sea Spray, Gas Fluxes, and Whitecaps (SEASAW) Experiment ». Dans Nucleation and Atmospheric Aerosols, 1050–54. Dordrecht : Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6475-3_208.

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Morency, Maurice, Denise Fontaine et Guoji Shan. « Physicochemical Characterisation and Recycling of Industrial Residues ». Dans Perspectives on Industrial Ecology, 67–81. Routledge, 2017. http://dx.doi.org/10.4324/9781351282086-7.

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Prakashan, D. « Nanomaterials for Tissue Engineering : Synthesis, Characterisation and Application ». Dans Nanoparticle Toxicity and Compatibility, 27–63. Materials Research Forum LLC, 2024. http://dx.doi.org/10.21741/9781644902998-2.

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Tissue engineering has recently become an effective method for restoring and rebuilding injured tissues and organs. Scaffolds for tissue engineering are essential because they not only give targeted cells structural support, but also act as templates to direct regeneration of tissue and regulate structure of tissue. Nanomaterials of various types have gradually grown and attracted a wide spectrum of research interests over the previous few years due to their distinctive physicochemical properties and exceptional biocompatibility, allowing remarkable advancements in the repair of wounds, wound healing, regeneration of neural tissue, and cardiac tissue engineering. This chapter focuses on the most recent different types of nanomaterials, its synthesis method, functionalisation and characterisation method for the different application in tissue regeneration and engineering. The chapter also focusses on the developments in the usage of scaffolds, nanosheets, or hydrogels based on different nanomaterials that are designed to repair cartilage, bone, and skin tissues. We have also summarised the difficulties and potential of nanomaterial applications in tissue engineering.

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Ramírez de Agudelo, M. M., E. Mujica et J. A. Salazar. « Physicochemical characterisation of VGO MHCK catalysts and its extrapolation to catalytic activity ». Dans Studies in Surface Science and Catalysis, 279–86. Elsevier, 1999. http://dx.doi.org/10.1016/s0167-2991(99)80419-4.

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Sun, Runcang, J. Mark Lawther et W. B. Banks. « Isolation and physicochemical characterisation of xylose-rich pectic polysaccharide from wheat straw ». Dans Progress in Biotechnology, 637–43. Elsevier, 1996. http://dx.doi.org/10.1016/s0921-0423(96)80297-8.

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John, Vineetha, et Neethu Ninan. « Biodegradation of Nanocellulose Scaffolds ». Dans Nanocellulose-based Hybrid Systems for Tissue Engineering, 222–44. Royal Society of Chemistry, 2024. https://doi.org/10.1039/9781837673094-00222.

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This chapter covers the various biodegradation mechanisms of nanocellulose scaffolds using microorganisms, enzymes and radiation, where factors like pH, temperature and hydrophobicity play a vital role in the reduction of molecular weight and increase in crystallinity. In vivo and in vitro breakdown procedures are included which can follow the hydrolysis, enzymatic and/or thermal degradation steps. In reactive oxygen species (ROS)-mediated scaffold degradation studies, faster splitting facilitating cell infiltration, resulting in better neovascularisation and engraftment at the implanted site, is observed distinguished by improved swelling ratio, porosity and hydrophilicity. Quantifying methods used for characterisation, like X-ray diffraction, high-performance liquid chromatography, thermogravimetric analysis, nuclear magnetic resonance and others, to identify the typical comparative physicochemical changes in the pristine and degraded nanocellulose structures are explained. These non-destructive techniques allow quantitative assessment and repeated measurement of the same sample which is an added advantage during the degradation process.

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Actes de conférences sur le sujet "Physicochemical characterisations"

Dodoo, Daniel, Francis Kotoka, Godfred Appiah et Samuel Tulashie. « Oil produced from Ghana cocoa bean for potential industrial applications ». Dans 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/fzpf7288.

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Cocoa bean (Theobroma cacao) oil is a promising intermediate cocoa product with few research demonstrating its potential for the direct production of industrial cocoa products. The liquefied form could be utilised as an intermediate cocoa bean product to manufacture industrial cocoa products with a controllable yield and low cost. This study highlights the extraction and characterisations of oil obtained from the Ghana cocoa bean crop to evaluate its suitability for industrial applications. A solvent extraction method was employed to extract the oil at variable extraction temperatures and times. Kinetic and thermodynamic models were adopted to study the oil's extraction at varying temperatures and times. The maximum yield of the oil (21.62%) was reached at the highest temperature and time at 333 K and 130 min, respectively, following first-order kinetics. The thermodynamic studies indicated that the extraction process is a forward, irreversible, endothermic, and spontaneously favourable process with activation energy 15.57 kJ mol-1. Next, the physicochemical properties were below the recommended values and acceptable for industrial and commercial applications. For instance, the oil's iodine, peroxide, saponification, unsaponification, and free fatty acids were below the recommended standards acceptable for industrial applications. The gas chromatography identified stearic acid (37%), oleic acid (34%), and palmitic acid (26%) as the major fatty acids in the oil. Differential scanning calorimetry “thermal gravimetric studies showed that the oil was thermally stable at high temperatures until thermal decomposition occurred around 260Â°C. Likewise, computational modelling and Fourier infrared red spectroscopy analysis revealed that the oil was highly stable to thermal oxidation despite the high temperatures employed for the extraction process. All in all, the results indicate that the extraction process can be optimised to maximise the oil's yield and reduce production costs. The oil's chemical and physical properties make it a suitable intermediate cocoa product for industrial applications.

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Rosli, Nurul Liyana, Ku Halim Ku Halim et Rusmi Alias. « Crude Palm Oil Physicochemical and Quality Characterisation ». Dans 5th International Conference on Global Sustainability and Chemical Engineering 2021 (ICGSCE2021). Switzerland : Trans Tech Publications Ltd, 2023. http://dx.doi.org/10.4028/p-j4n8l5.

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Crude Palm Oil (CPO) is extracted from the mesocarp of fruit obtained from the oil palm tree, which is also known as Elaeis guineensis. CPO contains Free Fatty Acid (FFA), which is one of the unnecessary constituents in CPO that is not good for food items and human consumption. Various methods for the deacidification process led to maximising the processing time, energy, and operating costs. Therefore, the aim of this research is to do a physical upgrading of the CPO, which may remove the FFA from the CPO while minimising the processing time, energy, and operating costs. However, prior to the physical upgrading of the CPO, it is important to highlight the physicochemical and quality characterisation of the CPO, which is essential and becomes a necessary procedure before the refining process. The purpose of this research is to examine the physicochemical and quality characteristics, which are fatty acid composition and FFA content, of the CPO, respectively. The American Oil Chemists’ Society (AOCS) method was used for this research work. The results showed the percentage of palmitic acid, stearic acid, oleic acid, and linoleic acid of the CPO were 40.1 %, 2.5 %, 37.5 %, and 19.9 %, respectively. The FFA content of the CPO was 4.90 %. The findings indicated the CPO met the recommended value by the Malaysian Palm Oil Board (MPOB). The physicochemical and quality characterisation of the CPO provide information as a guideline before the physical upgrading of the CPO that may produce palm oil products with good constituents for human health and the food industry.

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Titah, Harmin Sulistiyaning, Herman Pratikno et Atiek Moesriati. « Physicochemical characterisation of seawater at area of ship dismantling activities ». Dans THE 2ND INTERNATIONAL CONFERENCE ON SCIENCE, MATHEMATICS, ENVIRONMENT, AND EDUCATION. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5139859.

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Wágberg, Lars, et Göran Annergren. « Physicochemical Characterization of Papermaking Fibres ». Dans The Fundamentals of Papermaking Materials, sous la direction de C. F. Baker. Fundamental Research Committee (FRC), Manchester, 1997. http://dx.doi.org/10.15376/frc.1997.1.1.

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The purpose of this paper is to present as complete as possible, a picture of our present knowledge about papermaking fibres and their physico-chemical characteristics. The properties of the papermaking fibres are, in most cases, significantly influenced by the morphology of the wood fibres, but, from one and the same kind of wood fibres, paper can be produced with widely different properties as a result of different pulping and papermaking processes. Dissolution of material from the fibre wall and the middle lamella, structural changes of the polymeric material, and mechanical work on the fibrous material (defibration, refining, and to a certain extent undesired mechanical damage to the fibres in the pulp mill machinery) combine to produce the fibre properties required in the papermaking process. Starting from the structure of the wood, a survey is given of the pattern of dissolution of different important pulping processes and the resulting bulk composition of the pulps. Characterisation of papermaking properties should include effects of both bulk and surface of the fibres and for that reason they are both discussed. The bulk composition has been studied for many years and we have a fairly good knowledge of the main features, although there is still a need for more detailed knowledge. The properties of the fibre surface are less known, but they have been the subject of several recent studies. They are therefore dealt with in more detail, particularly the problem of making reliable and relevant measurements. Dissolution of lignin and other components in the pulping process is also important for the chemical composition of the surface. Mechanical removal of the remaining middle lamella and the outer layers of the fibre wall (the primary wall and SI of the secondary wall) substantially change the surface composition and create fines with a large surface area, which may interact with the wet-end chemicals in the paper mill and decrease the over-all effects of these chemicals. Removal of the outer layers will also change the fibre properties as a whole since, for instance, the SI layer restricts outward swelling of the main part of the secondary wall, S2, and preserves fibre rigidity. Swelling of the fibres influences there fining behaviour of a pulp. For lignin-containing pulps, swelling facilitates refining. For bleached pulps with a very low content of residual lignin, the effect of swelling on refining is rather difficult to as will be briefly discussed.

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« Physicochemical Characterisation and Phenolic Content of Algerian Honey Samples Collected from Different Bioclimatic Areas ». Dans Dec. 15-16, 2022 Istanbul (Turkey). Dignified Researchers Publication, 2022. http://dx.doi.org/10.17758/dirpub13.dir1222295.

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Rabi Prasad, B., Polaki Suman, Goutam Ghosh et Radha Krushna Padhi. « Physicochemical characterisation of lignocellulosic biomass for the identification of potential candidacy towards alternative renewable energy ». Dans 2023 International Conference on Power, Instrumentation, Energy and Control (PIECON). IEEE, 2023. http://dx.doi.org/10.1109/piecon56912.2023.10085857.

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Toma, F. L., L. M. Berger, T. Naumann et S. Langner. « Characterisation of Ceramic Nanostructured Coatings Prepared by Thermal Spraying of Suspensions ». Dans ITSC2008, sous la direction de B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima et G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p0417.

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Abstract Functional characteristics of materials including the mechanical, electrical, environmental and tribological performance can be significantly improved using nanostructured feedstock. Over the last few years much research has been dedicated to the development of thermal spraying techniques with liquid precursors to prepare fine nanostructured coatings. In this work nanostructured ceramic coatings were prepared using the technique of suspension spraying. Titania and alumina powders with sizes in the nanometre to submicrometre range were used to prepare aqueous and alcoholic suspensions. Atmospheric plasma and high-velocity flame were employed as enthalpy sources. The morphologies and crystalline structures of the sprayed ceramics were mainly characterised by SEM and XRD. The aim of this work was to carry out a comparative study and to discuss the nanostructured ceramic coating microstructures as a function of the physicochemical properties of the feedstock suspensions and spraying parameters.

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Stucchi, N. M. E., C. De Nardi, G. Franceschin, L. Ronchin, A. Vavasori et A. Traviglia. « Characterisation of Innovative Mortar Formulations for the Restoration of Roman Mosaics ». Dans Cardiff University Engineering Research Conference 2023. Cardiff University Press, 2024. http://dx.doi.org/10.18573/conf1.o.

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This contribution is focused on the study of the workability and mechanical properties of innovative mortars previously developed for preservation of ancient mosaics. The new formulations are based on the study of the Vitruvian recipe for Roman mortars, respecting the compatibility criteria with the original material. Different additives in different concentrations have been added to the previous formulations with the aim of studying their role in improving the durability, physicochemical, and rheological properties of the consolidating formulations. Preliminary slump tests were carried out to evaluate the effect of the additives on the workability of designed lime-based mortars. The achieved results highlighted the benefits of the use of plant-derived gel and inorganic nanoparticles in mortar mixtures, when added in suitable concentration. Considering these results, the best mortars formulations have been selected to examine in depth their mechanical properties.

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Kostić, Marijana S., Nikola D. Radnović, Ana Radović, David Kočović, Željko Jaćimović, Berta Barta Holló et Mirjana M. Radanović. « Synthesis and physicochemical characterisation of the Ni(II) complex with 3- (4-chlorophenyl)-1H-pyrazole ligand ». Dans 2nd International Conference on Chemo and Bioinformatics. Institute for Information Technologies, University of Kragujevac, 2023. http://dx.doi.org/10.46793/iccbi23.527k.

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The coordination properties of 3-(4-chlorophenyl)-1H-pyrazole (HL) was investigated and its complex with Ni(II) ion was synthesized. The structure of the ligand was proven using SC-XRD, while both the ligand and the complex were characterized by spectroscopic, and thermogravimetric measurements. The purity and composition of the complex were confirmed by PXRD, elemental analysis, and conductometric measurements. Besides, the search for CSD was made to establish the frequency of different coordination modes of similar compounds. It was found that monodentate coordination of the neutral ligand molecule or the exo-bidentate one in the case of the deprotonation of the pyrazole ring is possible. Based on the results obtained, the formula [Ni2(μ-L)2(OH)2(H2O)2]·2H2O and the bridging bidentate coordination of the monoanionic form of the ligand via nitrogen atoms of the pyrazole ring was suggested.

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Nyambi, Ntiyiso Faith, Kasturie Premlall et Krishna Kuben Govender. « The Physicochemical Characterisation and Computational Studies of Tilapia Fish Scales as a Green Inhibitor for Steel Corrosion ». Dans International Electronic Conference on Processes, 34. Basel Switzerland : MDPI, 2024. http://dx.doi.org/10.3390/engproc2024067034.

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Rapports d'organisations sur le sujet "Physicochemical characterisations"

Azzi, Elias S., Cecilia Sundberg, Helena Söderqvist, Tom Källgren, Harald Cederlund et Haichao Li. Guidelines for estimation of biochar durability : Background report. Department of Energy and Technology, Swedish University of Agricultural Sciences, 2023. http://dx.doi.org/10.54612/a.lkbuavb9qc.

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Biochar is produced by heating biomass in the total or partial absence of oxygen. This report addresses the long-term persistence of biochar in soil and how this can be managed in climate calculations and reporting. The report consists of this summary and four chapters, which can be read independently. Different terms have been used to describe the durability of biochar carbon storage, but also the physical presence of biochar in soils, e.g. persistence, permanence, recalcitrance, residence times, stability. Today, the term “durability of carbon storage” is preferred in policy contexts, but various academic disciplines such as soil science have other established terms like “persistence”. Here, both durability and persistence are used, rather interchangeably. It is important to be aware of differences in meaning that exist between disciplines. The purpose of this report is to present the state of knowledge regarding the proportion of carbon in biochar that remains in the soil over time and provide recommendations for calculating this. There is a need to calculate the persistence of biochar in soil for national climate reporting, corporate climate reporting, carbon credit trading, and life cycle assessments for various purposes. On the persistence of biochar The amount of biochar remaining after a certain time depends on the properties of the biochar and the environment in which it is located. Nearly all research on biochar persistence has focused on its application in agricultural soils. The main reason for the high durability of biochar carbon storage is the formation of fused aromatic stable structures during biomass pyrolysis. A high degree of fused aromatic structures makes biochar much less prone to microbial decomposition than fresh biomass. Different biochars have different properties, and this influences how long they persist in the soil. To achieve biochar with properties that provide higher persistence, it should be produced at higher temperatures for a sufficient duration. Measuring and calculating biochar persistence Established quantification methods of 100-year biochar persistence (e.g. referenced in IPCC inventory guidelines and used in voluntary carbon markets, to date) extrapolate short-term soil decomposition processes, and do not fully consider the processes that may explain millennial persistence. Calculations regarding biochar persistence have traditionally used a time span of 100 years to describe the amount of remaining carbon after a certain time. The use of specifically 100 years lacks a well founded scientific reason, but has been regarded as “far enough” into the future from a climate perspective and close enough for modelling to be meaningful. An active area of research relevant for the understanding biochar carbon storage durability is the development of advanced analytical characterisation methods of biochar that will enable measurement of the physicochemical heterogeneity in carbon structures present in biochar. Another area of continued research is biochar incubation, with a focus on field conditions, to elucidate both differences from laboratory conditions, and how transport processes affect biochar in the field. Recommendation and conclusion In the project, available research data has been aggregated into a functional model that calculates how much of the carbon in biochar remains after a given number of years. The model is based on the H/C ratio of the biochar placed in the soil and the annual average temperature at the location. The model is made freely accessible to provide biochar market actors with the best available knowledge for estimating the durability of biochar carbon. Existing research results provide a sufficient foundation for estimation of the amount of biochar expected to remain over time. Future research results are expected to lead to increased knowledge regarding the decomposition properties of biochar, in particular biochars with a very low H/C ratio. Therefore, this recommendation will be revised by the end of the project in 2025.

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