Academic literature on the topic 'Chemical LTP'
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Journal articles on the topic "Chemical LTP"
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Hoppanová, Lucia, Veronika Medvecká, Juliana Dylíková, Daniela Hudecová, Barbora Kaliňáková, Svetlana Kryštofová, and Anna Zahoranová. "Low-temperature plasma applications in chemical fungicide treatment reduction." Acta Chimica Slovaca 13, no. 1 (April 1, 2020): 26–33. http://dx.doi.org/10.2478/acs-2020-0005.
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AbstractIn order to reduce the environmental burden of chemicals, various new alternatives to seed protection are being sought. Our aim was to find an environmentally acceptable solution leading to the inactivation of seed-borne phytopathogenic fungi Fusarium culmorum on the surface of wheat and barley seeds with a positive effect on their germination. As a low-temperature plasma (LTP) source, a Diffuse Coplanar Surface Barrier Discharge (DCSBD) was used. Plasma generated by DCSBD is non-equilibrium, cold, diffuse, macroscopically homogeneous even in ambient air at atmospheric pressure. Experimental results showed that LTP treatment in the range of 120—300 s significantly inhibits the growth of F. culmorum on the surface of the seeds. The efficiency of LTP treatment was compared with traditional seed protection processes using chemical fungicide and also with combined seed pretreatment by plasma and subsequent application of chemical fungicide. No growth of F. culmorum was observed after the combination of Vitavax 2000 fungicide application in the dose of 10 % and 60 s of LTP treatment even on the 5th day of incubation. Better wettability of seeds with the chemical fungicide was related to the change on seed surface, which becomes hydrophilic after 10 s of LTP application. Short LTP exposure times did not affect germination and improved the growth parameter of cereal seeds. By combining physical (LTP) and chemical (Vitavax 2000) treatments of cereal seeds, it is possible to effectively reduce the required amount of chemical fungicide and to stimulate germination and early growth seed parameters.
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Ahmad, Faraz, Yu Jing, Albert Lladó, and Ping Liu. "Chemical Stimulation of Rodent and Human Cortical Synaptosomes: Implications in Neurodegeneration." Cells 10, no. 5 (May 12, 2021): 1174. http://dx.doi.org/10.3390/cells10051174.
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Synaptic plasticity events, including long-term potentiation (LTP), are often regarded as correlates of brain functions of memory and cognition. One of the central players in these plasticity-related phenomena is the α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor (AMPAR). Increased levels of AMPARs on postsynaptic membranes thus constitute a biochemical measure of LTP. Isolated synaptic terminals (synaptosomes) are an excellent ex vivo tool to monitor synaptic physiology in healthy and diseased brains, particularly in human research. We herein describe three protocols for chemically-induced LTP (cLTP) in synaptosomes from both rodent and human brain tissues. Two of these chemical stimulation protocols are described for the first time in synaptosomes. A pharmacological block of synaptosomal actin dynamics confirmed the efficiency of the cLTP protocols. Furthermore, the study prototypically evaluated the deficiency of cLTP in cortical synaptosomes obtained from human cases of early-onset Alzheimer’s disease (EOAD) and frontotemporal lobar degeneration (FLTD), as well as an animal model that mimics FLTD.
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Boccella, Serena, Ida Marabese, Monica Iannotta, Carmela Belardo, Volker Neugebauer, Mariacristina Mazzitelli, Gorizio Pieretti, Sabatino Maione, and Enza Palazzo. "Metabotropic Glutamate Receptor 5 and 8 Modulate the Ameliorative Effect of Ultramicronized Palmitoylethanolamide on Cognitive Decline Associated with Neuropathic Pain." International Journal of Molecular Sciences 20, no. 7 (April 9, 2019): 1757. http://dx.doi.org/10.3390/ijms20071757.
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This study investigated whether metabotropic glutamate receptor (mGluR) 5 and 8 are involved in the effect of ultramicronizedpalmitoylethanolamide (um-PEA) on the cognitive behavior and long term potentiation (LTP) at entorhinal cortex (LEC)-dentate gyrus (DG) pathway in mice rendered neuropathic by the spare nerve injury (SNI). SNI reduced discriminative memory and LTP. Um-PEA treatment started after the development of neuropathic pain had no effects in sham mice, whereas it restored cognitive behavior and LTP in SNI mice. 2-Methyl-6-(phenylethynyl) pyridine (MPEP), a selective mGluR5 antagonist, improved cognition in SNI mice and produced a chemical long term depression of the field excitatory postsynaptic potentials (fEPSPs) in sham and SNI mice. After theta burst stimulation (TBS) MPEP restored LTP in SNI mice. In combination with PEA, MPEP antagonized the PEA effect on discriminative memory and decreased LTP in SNI mice. The (RS)-4-(1-amino-1-carboxyethyl)phthalic acid (MDCPG), a selective mGluR8 antagonist, did not affect discriminative memory, but it induced a chemical LTP and prevented the enhancement of fEPSPs after TBS in SNI mice which were treated or not treated with PEA. The effect of PEA on LTP and cognitive behavior was modulated by mGluR5 and mGluR8. In particular in the SNI conditions, the mGluR5 blockade facilitated memory and LTP, but prevented the beneficial effects of PEA on discriminative memory while the mGluR8 blockade, which was ineffective in itself, prevented the favorable action of the PEA on LTP. Thus, although their opposite roles (excitatory/inhibitory of the two receptor subtypes on the glutamatergic system), they appeared to be required for the neuroprotective effect of PEA in conditions of neuropathic pain.
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Bhalla, Upinder S. "Multiscale interactions between chemical and electric signaling in LTP induction, LTP reversal and dendritic excitability." Neural Networks 24, no. 9 (November 2011): 943–49. http://dx.doi.org/10.1016/j.neunet.2011.05.001.
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Zhang, Lin, Xu Zhao, Yabin Zhao, Fujian Xu, Jinglin Kong, Zhian Hu, Mingying Ma, Sichun Zhang, and Xinrong Zhang. "Rapid analysis of chemical warfare agents by metal needle-enhanced low-temperature plasma mass spectrometry." Analytical Methods 11, no. 29 (2019): 3721–26. http://dx.doi.org/10.1039/c9ay00886a.
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KAN, C. W., C. W. M. YUEN, C. K. CHAN, and M. P. LAU. "EFFECT OF SURFACE TREATMENT ON THE PROPERTIES OF WOOL FABRIC." Surface Review and Letters 14, no. 04 (August 2007): 559–63. http://dx.doi.org/10.1142/s0218625x07009840.
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Wool fiber is commonly used in textile industry, however, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling, and dyeability. These problems may be attributed mainly in the presence of wool scales on the fiber surface. Recently, chemical treatments such as oxidation and reduction are the commonly used descaling methods in the industry. However, as a result of the pollution caused by various chemical treatments, physical treatment such as low temperature plasma (LTP) treatment has been introduced recently because it is similarly capable of achieving a comparable descaling effect. Most of the discussions on the applications of LTP treatment on wool fiber were focused on applying this technique for improving the surface wettability and shrink resistance. Meanwhile, little discussion has been made on the mechanical properties, thermal properties, and the air permeability. In this paper, wool fabric was treated with LTP treatment with the use of a non-polymerizing gas, namely oxygen. After the LTP treatment, the fabrics low-stress mechanical properties, air permeability, and thermal properties were evaluated and discussed.
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Li, Wei, Xin Xu, and Lucas Pozzo-Miller. "Excitatory synapses are stronger in the hippocampus of Rett syndrome mice due to altered synaptic trafficking of AMPA-type glutamate receptors." Proceedings of the National Academy of Sciences 113, no. 11 (February 29, 2016): E1575—E1584. http://dx.doi.org/10.1073/pnas.1517244113.
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Deficits in long-term potentiation (LTP) at central excitatory synapses are thought to contribute to cognitive impairments in neurodevelopmental disorders associated with intellectual disability and autism. Using the methyl-CpG-binding protein 2 (Mecp2) knockout (KO) mouse model of Rett syndrome, we show that naïve excitatory synapses onto hippocampal pyramidal neurons of symptomatic mice have all of the hallmarks of potentiated synapses. Stronger Mecp2 KO synapses failed to undergo LTP after either theta-burst afferent stimulation or pairing afferent stimulation with postsynaptic depolarization. On the other hand, basal synaptic strength and LTP were not affected in slices from younger presymptomatic Mecp2 KO mice. Furthermore, spine synapses in pyramidal neurons from symptomatic Mecp2 KO are larger and do not grow in size or incorporate GluA1 subunits after electrical or chemical LTP. Our data suggest that LTP is occluded in Mecp2 KO mice by already potentiated synapses. The higher surface levels of GluA1-containing receptors are consistent with altered expression levels of proteins involved in AMPA receptor trafficking, suggesting previously unidentified targets for therapeutic intervention for Rett syndrome and other MECP2-related disorders.
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Yang, Shao-Nian, Yun-Gui Tang, and Robert S. Zucker. "Selective Induction of LTP and LTD by Postsynaptic [Ca2+]i Elevation." Journal of Neurophysiology 81, no. 2 (February 1, 1999): 781–87. http://dx.doi.org/10.1152/jn.1999.81.2.781.
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Selective Induction of LTP and LTD by Postsynaptic [Ca2+]i Elevation. Long-term potentiation (LTP) and long-term depression (LTD), two prominent forms of synaptic plasticity at glutamatergic afferents to CA1 hippocampal pyramidal cells, are both triggered by the elevation of postsynaptic intracellular calcium concentration ([Ca2+]i). To understand how one signaling molecule can be responsible for triggering two opposing forms of synaptic modulation, different postsynaptic [Ca2+]i elevation patterns were generated by a new caged calcium compound nitrophenyl-ethylene glycol-bis(β-aminoethyl ether)- N, N, N′, N′-tetraacetic acid in CA1 pyramidal cells. We found that specific patterns of [Ca2+]i elevation selectively activate LTP or LTD. In particular, only LTP was triggered by a brief increase of [Ca2+]i with relatively high magnitude, which mimics the [Ca2+]i rise during electrical stimulation typically used to induce LTP. In contrast, a prolonged modest rise of [Ca2+]i reliably induced LTD. An important implication of the results is that both the amplitude and the duration of an intracellular chemical signal can carry significant biological information.
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Ngamsomrit, S., T. Eknapakul, S. Pinitsoontorn, and P. Songsiriritthigul. "Effect of Mn grinding time on structural, chemical, and magnetic properties of the Manganese Bismuth prepared by sintering in vacuum." Journal of Physics: Conference Series 2431, no. 1 (January 1, 2023): 012060. http://dx.doi.org/10.1088/1742-6596/2431/1/012060.
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Abstract This work reports the changes in structural, chemical, and magnetic properties of the low-temperature phase manganese bismuth (LTP-MnBi) sintered from mixtures of Bi and Mn ball-milled for different times. The milling time was varied from 1 to 15 hr to produce Mn powder with different particle sizes. The average particle size reduced from ~400 µm (original size) to 35 ± 5 µm and 6 ± 2 µm after 1 and 15 hr milling times, respectively. The LTP-MnBi powder was sintered at 275 °C at vacuum pressure below 5 × 10−7 mbar for 12 hours. By increasing the Mn grinding time, the maximum energy product ((BH)max) of LTP-MnBi decreased from 1.98 ± 0.05 to 1.59 ± 0.07 MGOe, and the saturation magnetization (M s) decreased from 53.42 ± 0.90 to 44.32 ± 0.72 emu/g. The x-ray diffraction patterns indicated the reduction of LTP-MnBi content as a function of the milling time, which is agreed with the decrease in the M s value. This is supported by the x-ray photoelectron results, which also showed the increment of Mn oxides on the surface as a function of Mn milling time. The unexpected decrease in M s, which results in a significant reduction of magnetic performance, might be due to the presence of the oxides preventing diffusion during sintering.
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KAN, C. W., C. W. M. YUEN, and S. Q. JIANG. "EFFECT OF SURFACE TREATMENT ON THE ENZYMATIC TREATMENT OF CELLULOSIC FIBER." Surface Review and Letters 14, no. 04 (August 2007): 565–69. http://dx.doi.org/10.1142/s0218625x07009852.
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Fiber modifications by environmentally friendly processing are essential in order to simplify the preparation and finishing processes, in addition to minimizing the chemical waste and associated disposal problem. In this regard, enzymes have been used extensively because it can remove the small fiber ends from yarn surface to create a smooth fabric surface appearance and introduce a degree of softness without using traditional chemical treatment. However, a significant strength reduction and slow reaction rate of the enzymatic reaction limit its industrial application. In this paper, the potential of using low-temperature plasma (LTP) as a surface pre-treatment prior to enzyme treatment on flax fiber has been studied. By means of the LTP pre-treatment, the effectiveness of enzyme treatment can be enhanced.
Dissertations / Theses on the topic "Chemical LTP"
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Montalbano, Alberto. "Synaptic plasticity regulation mediated by BDNF: functional and morphological study." Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7404.
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2010/2011The long-term potentiation (LTP) represents a widely studied form of synaptic plasticity related to learning and memory processes, which involves a long-lasting strengthening of synaptic connections through changes of their transmission and cytoarchitecture. The induction of LTP is classically achieved by tetanic stimulation of presynaptic components but it is also possible to in- duce chemically a long-term potentiation of the synaptic efficacy, thus enhancing a larger number of synapses compared to electrical stimulation and facilitating the biochemical and morphological study. The first part of this thesis is a methodological study of glycine and tetraethylammonium (TEA) induced chemical LTP (cLTP) in cultured hippocampal cells. Brief glycine (in Mg2+-free) application activate NMDA receptors, whereas TEA blocks of K+ channels inducing a depolariza- tion responsible for Ca2+ influx. Both drugs were briefly superfused and mEPSCs were monitored for all the duration of the experiments (≃60 min). This was considered as a necessary step to detect later the role of the Brain Derived Neurophic Factor (BDNF) in cLTP. Healthy hippocampal cells were dissected from rats of postnatal day 1-2. After a period of 10-12 days in vitro the cells reached optimal density, a typical mature pyramidal neuron morphology, and an extended dendritic arborization which facilitates synaptic contacts. At this stage patch-clamp technique in the whole-cell configuration was used to study the electrophysiological properties of pyramidal hippocampal neurons, able to produce spontaneous electrical activity. cLTP was tested recording miniature excitatory postsynaptic currents (mEPSCs) in voltage-clamp mode focusing on changes in their amplitude and frequency. A significant decrease in mEPSCs inter-event intervals was observed after glycine and TEA application, without significant changes in aptitudes. Therefore 20 min after glycine application an increase (≃ 61.6 %) in mEPSCs frequency was observed. A similar result was obtained also after TEA application (≃ 66 %). Following cLTP we observed also morphological changes such as an increase in density and a remodeling of different classes of dendritic spines. The role of BDNF in this cLTP model was assessed testing by ELISA assay the total BDNF expres- sion on cell lysate and by blocking Tropomyosin Receptor Kinase (Trk) with K252A. A significant increase in BDNF levels (≃ 120 %) was observed 50 min after cLTP induction. A switch from cLTP into cLTD was observed blocking Trk receptors. Moreover, confocal images collected before and after chemical potentiation in the presence of K252A showed a significant reduction (≃10%) in the average spine density both at the proximal and distal level. A significant reduction of the p-TrkB/TrkB ratio, after both gly- and TEA-LTP, was observed in distal dendrites compared to the soma. This therefore suggests a translocation of the activated receptor from periphery to the soma.
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Carey, Thomas. "Chemical control of thermal expansion in zeolites with the LTA topology." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4258/.
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Zeolites are microporous materials that have been commonly shown to exhibit remarkable negative thermal expansion (NTE) behaviour in their purely siliceous forms, with reported thermal expansion coefficients ranging from −3 x 10–\(_6\) K–\(_1\) to −26.1 x 10–\(_6\) K–\(_1\). In contrast, very little research has been reported on the aluminium-containing structures which are widely used for various commercial applications. Compounds exhibiting this property, which has only been observed in a small number of solids, are of considerable technological interest as their inclusion in devices or composite materials can counterbalance the more usual expansion on heating and contraction on cooling, thereby reducing the incidence of thermally induced failures. Here, we report an investigation into the effect that changing the chemical composition of the zeolite framework and intrapore species has on thermal expansion properties of zeolites with the LTA topology. Variable-temperature powder X−ray diffraction studies were used to determine the thermal expansion coefficients of the chemically modified zeolites over a sub-ambient temperature range and investigate the structural basis behind their thermal behaviour. Dramatic changes in the thermal expansion behaviour (from strong negative to weak positive) of the zeolites were observed as the structures were modified through ion-exchange, dehydration, varying the Al content in the framework and loading the pores with silver nitrate. The zeolitic pores contents have been shown to play a key role in the manner in which LTA-zeolites react to temperature variation, especially in the case of intra-porous water molecules. Detailed atomistic structural mechanisms behind the observed NTE behaviour have been produced for the more simplistic systems. Several key breakthroughs have also been achieved in understanding the formation of the superlattice when silver nitrate is incorporated into the zeolite pores and with regards to solving the unit cell structure.
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Galant, Malikaah. "The characterisation of the lead flotation circuit at Black Mountain Mining (Pty) Ltd. using the floatability component model approach." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/24313.
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Black Mountain Mining (Pty) Ltd. (BMM) is a base metal operation that has been producing chalcopyrite-, galena- and sphalerite-bearing concentrates for over 30 years. Silver is recovered in the concentrates as a result of elemental substitution within the crystal lattice of chalcopyrite and galena minerals. The primary objective of this study was to adapt the Floatability Component Model (FCM) as a simplified proof-of-concept model for the Lead flotation circuit of the BMM Concentrator based on plant- and laboratory-scale data. The model obtained, using the FCM approach in conjunction with the Woodburn and Wallin (1984) methodology, should give insight to the metallurgical team regarding the performance of the circuit based on the data pertaining to the feed characteristics of the Lead flotation circuit. Additionally, as a result of the known association of silver with galena minerals, an objective of the study was to be able to predict the response of silver based on the response of galena minerals. The model for the Lead flotation circuit of BMM Concentrator was developed in a single MS Excel spreadsheet and it was important that the raw data used to develop the model could be obtained easily, inexpensively and in a manner that was not disruptive to the operation.
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Chiu, Yen-ni, and chiuyenni@yahoo com au. "Ethoxylation reactor modelling and design." Swinburne University of Technology. Centre for Micro-Photonics, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20050610.140607.
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The manufacture of nonionic surfactants generally involves ethoxylation via ethylene oxide condensation onto a hydrophobe substrate, mostly in the presence of an alkaline catalyst. Nonionic surfactants are used widely in industrial applications, such as detergents, health and personal care, coatings, and polymers. In Australia, approximately one-third of the annual consumption of nonionic surfactants is imported from offshore manufacturers; the market is highly competitive with the local manufacturer facing increasing
competition from imports. Optimisation is a pressing need for the current manufacturing plant of the industrial partner for this research project, Huntsman Corporation Australia Pty Limited, the sole domestic manufacturer of nonionic surfactants in Australia. Therefore, the objectives of this research project were
to gain a better understanding of the various chemical and physical processes occurring
simultaneously in an ethoxylation process; to identify the process limitation in an existing production plant operated by Huntsman Corporation Australia, and to explore measures for enhancing the asset productivity of the production plant. An ethoxylation process working model, describing the chemical kinetics and the physical transport processes involved, was developed to aid the exploration of optimisation opportunities, which would
otherwise be empirical. Accordingly, this research project was structured into a two-stage program. The first stage determined the ethoxylation kinetics experimentally. The second stage investigated the interactions of physical transport processes numerically using a computational fluid dynamics (CFD) technique. The manufacturing scheme discussed in this thesis gave particular emphasis to the
ethoxylation process operated in semi-batch stirred reactors. In the first stage, a series of kinetic experiments was performed in a well-stirred laboratory autoclave under base-catalysed conditions. The experimental outcomes were developed into a comprehensive kinetic model which took into account the non-ideal features in the reactor operation. Time-dependent
physical changes of the reaction system, such as liquid volume, ethylene oxide solubility and density were also included. The ethoxylation behaviour predicted by the model was shown to be in good agreement with the experimental measurements. This indicated that the kinetic model was sufficiently robust to reproduce the reaction behaviour of a commercially operated ethoxylation operation. In the second stage, numerical simulations of an existing ethoxylation reactor system were presented.
In addition, two components were addressed: identification of the process limitation and increasing productivity of the industrial-scale ethoxylation plant. An important assumption was made for the ethylene oxide injection system used in this research project which subsequently simplified the ethoxylation system into a single liquid with miscible chemical species. In the identification of the process limitation, three possible rate-limiting factors were examined:
mixing, heat removal and reactor pressure rating. Examination and analysis of the physical data available from plant batch reports found that the reactor pressure rating and the presence of nitrogen padding were the rate-limiting factors to the ethoxylation operations in the industrial reactors. It was recommended that the reactor pressure rating be increased to raise the asset productivity of the reactor.
In the numerical simulations of the ethoxylation reactor, time-dependent CFD models were developed for two systems: the ethylene oxide injection pipe and the stirred ethoxylation reactors. The heat transfer of ethylene oxide liquid injection was calculated in a two-dimensional model of the dip-leg pipe used in an industrial-scale ethoxylation reactor. The computation gave the temperature of the
injection outflow which was validated against the calculated value by empirical correlation. The effects of various surrounding reaction temperatures, injection rates and pipe sizes on the heat transfer rate were investigated. From these, a range of operating conditions yielding a liquid ethylene oxide outflow was selected. Furthermore, it was found that boiling of ethylene oxide was significantly reduced with increasing pipe diameters. It was recommended that the asset productivity of the reactor be improved by keeping more ethylene oxide injected as a liquid in the reaction mixture to raise the reaction rate and shorten the reaction time.
Three-dimensional simulations of a baffled reactor agitated by a single- or a dual-Rushton impeller were presented for both non-reactive and reactive flows. Multiple frames of reference and sliding grid methods were used in sequence to describe the relative motion between the rotating impeller and the stationary baffles. The turbulence parameters were modelled with the standard k- � turbulence model. The simulations of non-reactive flow were compared with the literature velocity data obtained from both the experiments and simulations. Good agreement was achieved. The model was then extended to
incorporate ethoxylation flow with integration of the kinetics established in the first stage. Both the laboratory autoclave and the industrial-scale reactors were simulated. The former took into account the ethoxylation exotherm and the latter was carried out isothermally. Both simulations were validated against reaction data obtained from physical experiments, either the kinetic experiments or the plant batch
productions. The validated model allowed us to determine the optimum operating condition and explore a new reactor system with enhanced asset productivity. A 50% increase in productivity could be accomplished if the ethoxylation was operated closer to the current design pressure limit. Furthermore, the operating pressure of a new reactor system needed to be doubled if the asset productivity were to be increased to approximately three times the current performance.
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Chiu, Yen-ni. "Ethoxylation reactor modelling and design." Australasian Digital Thesis Program, 2005. http://adt.lib.swin.edu.au/public/adt-VSWT20050610.140607.
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Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, Centre for Micro-Photonics, 2005.A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy, Centre for Micro-Photonics, Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, 2005. Typescript. Bibliography: p. 201-210. Also available on cd-rom.
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Stonkutė, Edita. "Chemical composition of kinematically identified galactic stellar group." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130925_093107-33619.
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A number of stellar streams, moving and kinematic groups were identified in the Milky Way galaxy. Some of them are suspected to originate from accreted satellites. Can we also find such traces of ancient merger events in the solar neighbourhood? Helmi et al. (2006) identified three new coherent groups of stars in the Geneva-Copenhagen survey (Nordström et al. 2004) and suggested that those might correspond to remains of disrupted satellites.
With the detailed chemical composition analysis of the newly identified kinematic group we aim to contribute to the Galactic substructure studies. The main aim of the study is to perform a high-resolution spectroscopic elemental abundance analysis in stars belonging to one of the newly identified kinematic groups and to compare the results with other stars in the Galactic disc.
We performed the detailed chemical analysis of 21 stars attributed to Group 3 of the Geneva-Copenhagen survey and six comparison Galactic thin disc stars. The main atmospheric parameters and abundances of 22 chemical elements were determined. All programme stars are overabundant in oxygen and α-elements compared with the Galactic thin-disc. This abundance pattern has similar characteristics to those of the Galactic thick disc. The abundances of chemical elements produced predominantly by the r-process are overabundant in comparison with Galactic thin-disc dwarfs of the same metallicity. The abundances of iron-group elements and chemical elements produced mainly... [to full text]Paukščių Tako galaktikoje yra identifikuota žvaigždžių srautų, judančių bei kinematinių grupių, kurių kilmė siejama su įkritusiomis galaktikomis. Aktualu ištirti, ar yra tokių senųjų substruktūrų pėdsakų mūsų Saulės aplinkoje? Helmi ir kt. (2006), panaudoję Nordström ir kt. (2004) Ženevos–Kopenhagos apžvalgos (ŽKA) katalogą, identifikavo tris naujas koherentines žvaigždžių grupes, kurios pasižymi išskirtiniais kinematiniais parametrais ir gali būti užgalaktinės kilmės. Šiuo disertacijos darbu siekiama prisidėti prie Galaktikos substruktūrų tyrimų, nustatant detalią cheminę vienos iš Helmi ir kt. identifikuotų žvaigždžių grupių sudėtį. Svarbu išsiaiškinant, ar ŽKA kinematinės grupės žvaigždžių atmosferų cheminė sudėtis skiriasi nuo Galaktikos disko žvaigždžių. Nustatėme 21 3–osios ŽKA kinematinės grupės bei 6 palyginamųjų plonojo disko žvaigždžių atmosferų pagrindinius parametrus bei 22 cheminių elementų gausas. Kinematinės žvaigždžių grupės deguonies ir α–elementų gausos yra padidėjusios lyginant su plonuoju disku ir yra panašios į storojo disko. Cheminių elementų, daugiausia pagaminamų s–procese, gausos ir geležies grupės elementų gausos yra panašios į to paties metalingumo plonojo disko nykštukių cheminių elementų gausas, o cheminių elementų, daugiausia pagaminamų r–procese, gausos yra padidėjusios lyginant su plonuoju disku. Panaši cheminė tirtos kinematinės grupės bei storojo Galaktikos disko sudėtis rodo, kad kinematinės žvaigždžių grupės ir storojo disko žvaigždžių... [toliau žr. visą tekstą]
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Benvenga, Sérgio Roberto. "Neoleucinodes elegantalis (Guenée) (Lep.: Crambidae) em tomateiro estaqueado : dinâmica populacional, nível de controle com feromônio sexual e eficiência de agrotóxicos /." Jaboticabal : [s.n.], 2009. http://hdl.handle.net/11449/102319.
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Orientador: Sergio Antonio De BortoliBanca: José Eudes de Morais Oliveira
Banca: José Ednilson Miranda
Banca: Robson Thomaz Thuler
Banca: Marcelo da Costa Ferreira
Resumo: A relação entre a infestação da broca-pequena-do-fruto, Neoleucinodes elegantalis, e a produtividade foi avaliada na cultura do tomate, Lycopersicon esculentum, em ciclo de verão e inverno, com o objetivo de analisar a influência da infestação na produtividade da cultura e aperfeiçoar a tomada de decisão de controle. Armadilhas com feromônio sexual foram instaladas em parcelas experimentais e na mesma data foi avaliada a densidade de adultos capturados e a infestação de plantas com ovos nos frutos. A pressão populacional foi mais expressiva nos cultivos de verão. O aumento no número de adultos capturados nas armadilhas correspondeu a um incremento na infestação de ovos nos frutos e houve influência positiva da infestação de plantas com a produção descartada. Definiu-se que a tomada de decisão de controle deve ocorrer quando for capturada a média de 0,24 e de 0,23 adultos na armadilha por dia, nos cultivos de verão e de inverno, respectivamente. Numa etapa complementar avaliou-se a eficiência de inseticidas sobre os ovos (ação ovicida), lagartas recém-eclodidas (ação de choque) e em fase de crescimento (ação fisiológica), sob condições de laboratório. Para tanto, frutos com ovos foram imersos na calda inseticida para avaliação da ação ovicida e ação de choque aos 7 dias após a imersão e aos 21 dias, para a ação fisiológica. Foram avaliados 24 inseticidas e uma testemunha em aplicação isolada e com a adição de óleo vegetal (0,25%), respectivamente. Trebon 100 SC (etofenprox; 200 mL de produto comercial/100 L), Lannate BR (methomil; 100 mL), Thiobel 500 (cartap; 250 g) e Vertimec 18 CE (abamectin; 100 mL) apresentaram ação efetiva sobre os ovos e lagartas de N. elegantalis. A adição do adjuvante interfiriu de forma significativa e positiva na eficiência dos inseticidas.
Abstract: The relationship between the infestation of Neoleucinodes elegantalis and productivity was evaluated in tomato crops, Lycopersicon esculentum, in summer and winter cycles, with the objective of analyzing the infestation influence on the productivity and improving the decision making control. Sex pheromone traps were installed in experimental plots and at the same date was assessed the density of adults caught and infestation of plants with eggs in fruits. The population pressure was more significant in the summer crops. The increase in the number of adults caught in traps corresponded to an increase in infestation of eggs in the fruit and with positive influence of the infestation on plants with the production. Decision-making control should occur when the average catch of 0.24 and 0.23 adults in the trap per day in the summer and winter crops, respectively. An additional step was conducted to evaluate the efficiency of insecticides on the eggs (ovicidal action), newly-hatched larvae (shock action) and in the growth phase (physiological action) under laboratory conditions. Fruit with eggs were emmerged in the insecticide solutions for assessing ovicidal action and the shock action at 7 days after immersion and at 21 days, to physiological action. It was evaluated 24 insecticides and a control application in with and without addition of vegetable oil (0.25%). Trebon 100 SC (etofenprox; 200 mL of commercial product/100 L), Lannate BR (methomil; 100 mL), Thiobel 500 (cartap; 250 g) and Vertimec 18 EC (abamectin; 100 mL) had action on the eggs and larvae of N. elegantalis. The addition of adjuvant showed significantly and positively effects in the insecticides efficiency.
Doutor
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Mikolaitis, Šarūnas. "Evolutionary Effects of Chemical Composition in Red Giants of Open Clusters." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120913_085458-84188.
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Open clusters are important tools for studying of the Galactic disk and for understanding stellar evolution. Stars of clusters have constant age, composition and distance. This makes them to be excellent laboratories for investigations of stellar and Galactic chemical evolution. The main aim of the study is the analysis of mixing tracers and extra mixing evidences in photospheres of evolved stars. Extra-mixing processes may modify the surface abundances of 12^C/13^C and 12^C/14^N ratios. This study aims to test theoretical models. The secondary goal is a contribution to the study of present properties of the Galactic disc. The 12^C/13^C ratios in helium-core-burning clump stars for the clusters with turn-off masses lower than 2 solar masses are in agreement with the Cool-bottom processing (CBP) model and the Thermohaline mixing (TH) model. The observed 12^C/13^C ratios of the helium-core-burning stars in the open cluster NGC 6134 support evidences of larger then theoretically predicted extra-mixing in stars heavier than 2.5 solar masses. In two open clusters the 12^C/13^C ratios in core-helium-burning stars are lower than in the first ascent giants, located above the RGB luminosity bump. This could be caused by the material mixing during a very violent helium flash event. Almost all element to iron ratios show essentially flat radial abundance distributions across Galactic disk. The radial distributions of [O/Fe] and [Mg/Fe] have a tendency to increase towards larger... [to full text]Padrikieji spiečiai naudojami astrofizikoje, tiriant Galaktikos disko cheminę raidą bei žvaigždžių evoliuciją. Spiečiaus žvaigždžių amžius, atstumas nuo Saulės, pirminė cheminė sudėtis yra apytiksliai vienodi, tad juos galima laikyti kosminėmis laboratorijomis. Pagrindinis disertacijos tikslas skirtas tirti maišymosi procesus evoliucionavusiose žvaigždėse. Siekiama įvertinti kaip maišymosi procesai paveikia 12^C/13^C ir 12^C/14^N gausų santykius ir palyginti su teoriniais maišymosi modeliais. Kitas tikslas skirtas prisidėti prie Galaktikos disko cheminės sudėties bei evoliucijos tyrimo. 12^C/13^C ir 12^C/14^N gausų santykiai nustatyti penkių spiečių evoliucionavusių žvaigždžių atmosferose. Helį centre deginančiose žvaigždėse kurių žvaigždžių posūkio iš pagrindinės sekos masės (M_toff) yra mažesnės nei 2 saulės masės, 12^C/13^C santykiai gerai sutampa su termohalinio (TH) bei šaltojo žemutinių sluoksnių (CBP) papildomo maišymosi modeliais, o tokių spiečių kurių M_toff yra didesnės nei 2,5 saulės masių papildomas maišymasis yra didesnis nei numato teoriniai modeliai. Dviejuose padrikuosiuose spiečiuose anglies izotopų gausų santykiai helį centre deginančių žvaigždžių atmosferose yra mažesni nei žvaigždėse, perkopusiose šviesio mazgą raudonųjų milžinių sekoje. Tai galėtų būti dėl galimo papildomo medžiagos maišymosi helio žybsnio metu. Beveik visų tirtų elementų radialinis pasiskirstymas Galaktikoje yra iš esmės plokščias, bet [O/Fe] ir [Mg/Fe] gausos turi tendenciją augti... [toliau žr. visą tekstą]
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Garbarienė, Inga. "Origin, chemical composition and formation of submicron aerosol particles in the atmosphere." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140520_134625-72680.
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The objective of the work was to investigate physical and chemical properties and sources of the atmospheric aerosol particles in the submicron fraction by combining different analytical techniques. The dependence of concentrations of organic and elemental carbon in different air masses was determined and the contribution of regional and local sources to the net aerosol particle pollution was estimated. Analysis of the size distribution of carbonaceous aerosol particles in background and urban areas was performed. Biogenic organic aerosol made up 15 % of the organic aerosol mass at the Preila atmospheric pollution research station, but in the North Atlantic air masses this factor was up to 50 %. Aerosol and stable isotope ratio mass spectrometry has revealed that traffic is the primary source of aerosol particles in the city, while biomass burning is the primary source at the Rūgšteliškis background station. It was determined that secondary anthropogenic organic compounds were dominating (76 %) in Vilnius, while in Rūgšteliškis secondary biogenic organic compounds made up 50 % of the total organic aerosol mass. The influence of the long-range air mass transport on the local origin aerosol particle formation and transformation has been evaluated and it has been shown that volcanic aerosol particles can significantly change the concentration, chemical composition and size distribution of local aerosol particles in the submicron range.Disertacija skirta smulkiosios aerozolio dalelių frakcijos šaltinių, fizikinių ir cheminių savybių įvertinimui kompleksiškai apjungiant įvairius tyrimo metodus. Darbe susieti elementinės ir organinės anglies koncentracijų pokyčiai su tolimąja oro masių pernaša, įvertinta regiono bei vietinių šaltinių įtaka bendrai aerozolio dalelių taršai. Aprašyti anglies turinčių aerozolio dalelių pasiskirstymai pagal dydį foninėse vietovėse ir miesto aplinkoje. Naudojant aerozolio masių spektrometrą Preilos atmosferos užterštumo tyrimų stotyje buvo identifikuotas biogeninis organinių medžiagų šaltinis, kuris vidutiniškai sudaro 15 % nuo organinių medžiagų masės, tačiau Šiaurės Atlanto oro masėje biogeninių medžiagų indėlis siekia net 50 %. Atlikus kompleksinę aerozolio ir stabiliųjų anglies izotopų masių spektrometrinę analizę buvo nustatyta, kad pirminis anglies turinčio aerozolio dalelių šaltinis mieste yra autotransportas, o Rūgšteliškio foninėje vietovėje – biomasės deginimas. Taip pat buvo nustatyta, kad Vilniuje dominavo antropogeninės antrinės organinės medžiagos (76 %), o Rūgšteliškyje vyravo biogeninės antrinės organinės medžiagos (apie 50%). Vertinant tolimosios oro masių pernašos įtaką vietinės kilmės aerozolio dalelių formavimuisi ir kaitai, buvo nustatyta, kad vulkaninės kilmės aerozolio dalelės turi įtakos submikroninės aerozolio dalelių frakcijos koncentracijai, cheminei sudėčiai ir pasiskirstymui pagal dydį.
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Larsson, Carl-Emil. "Emission Problems and Opportunities from Calcium Carbide Production : A STUDY OF INNER MONGOLIA HAIJI CHLOR ALKALI-CHEMICALCO. LTD. IN WUHAI, CHINA." Thesis, KTH, Industriell ekologi, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-32715.
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This master thesis in Industrial Ecology has been carried out at Royal Institute of Technology, KTH, in cooperation with Swedish Environmental Research Institute, IVL andShandong University. It discusses the air pollution control techniques in calcium carbidemanufacturing by studying Inner Mongolia Haiji Chlor-Alkali Chemical Co. Ltd’s plants inWuhai, Inner Mongolia, China. China’s environmental situation is discussed and its severe state is found to be similar to the western world in the last century. One of the main reasons for the air pollution problems arethe coal based industries in cities like Wuhai. Calcium carbide is a chemical based on coaland limestone which in China is mainly used for PVC plastics production. The emission from the carbide production is mainly particulate matter. This is suggested to be controlled by adding cyclone and electrostatic precipitator as treatment for the waste gas. Investments in particulate matter control will be at least a few million SEK (similar in RMB),but the waste, both the solid and the gas, can be used in other processes, namely cementproduction, heat exchanging and as fuel. By investing in equipment to use this waste and sell the energy, it is expected that close to ten million RMB1 can be earned annually, meaning that the particulate matter control investment will pay off quickly. The Fischer-Tropschmethod for producing synthetic diesel from carbon monoxide and hydrogen gas provides another opportunity to use the waste gas.www.ima.kth.se
Books on the topic "Chemical LTP"
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Brodie, Patrick. Crescent over Cathay: China and ICI, 1898 to 1956. Hong Kong: Oxford University Press, 1990.
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Commission, Monopolies and Mergers. Kemira Oy and Imperial Chemical Industries PLC: A report on the proposed merger. London: H.M.S.O., 1991.
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Commission, Monopolies and Mergers. Kemira Oy and Imperial Chemical Industries PLC: A report on the proposed merger. London: H.M.S.O., 1991.
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Great Britain. Dept. of Trade and Industry., ed. BASF AG and Takeda Chemical Industries Ltd: A report on the acquisition by BASF AG of certain assets of Takeda Chemical Industries Ltd. London: Stationery Office, 2001.
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The awakening giant: Continuity and change in Imperial Chemical Industries. Oxford [Oxfordshire]: Blackwell, 1985.
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Great Britain. Health and Safety Executive., ed. Release of chemicals from International Biosynthetics Ltd: A report of the investigation by the Health and Safety Executive into the chemical emission from International Biosynthetics Ltd on 7 December 1991. London: HMSO, 1993.
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Coleman, Kim. IG Farben and ICI, 1925-53: Strategies for growth and survival. Houndmills, Basingstoke, Hampshire: Palgrave Macmillan, 2006.
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National Conference and Annual Paper Meet (2nd 2003 Brāhmanbāria, Bangladesh). Second National Conference and Annual Paper Meet (APM), January 23, 2003: Venue, Zia Fertilizer Company Ltd., Ashuganj Sub-Centre, Brahmanbaria. Dhaka: Chemical Engineering Division, The Institution of Engineers, 2003.
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ICI: The company that changed our lives. 2nd ed. London: P. Chapman Pub., 1993.
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ICI: The company that changed our lives. London: Hutchinson, 1986.
Find full textBook chapters on the topic "Chemical LTP"
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Lascelles, P. T., and D. Donaldson. "Fluorescein Dilaurate (Pancreolauryl, International Laboratories Ltd) Test5." In Diagnostic Function Tests in Chemical Pathology, 57–58. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1846-7_30.
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Tedeschi, Aurora. "Chemical Peeling for the Lip and the Eye Regions." In Nonsurgical Lip and Eye Rejuvenation Techniques, 37–43. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-23270-6_6.
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Davies, Martin, and Jiang Lin. "Shanghai Dingheng Shipping Co., Ltd. v. Liaoning Hua Xin Petroleum & Chemical Co., Ltd." In Chinese Maritime Cases, 1121–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2022. http://dx.doi.org/10.1007/978-3-662-64029-6_57.
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Davies, Martin, and Jiang Lin. "ZIM Integrated Shipping Services Co., Ltd. v. Hefei Salt Chemical Co., Ltd. et al." In Chinese Maritime Cases, 2055–76. Berlin, Heidelberg: Springer Berlin Heidelberg, 2022. http://dx.doi.org/10.1007/978-3-662-64029-6_104.
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Baur, W. H., and R. X. Fischer. "Crystal structure and chemical composition of compounds with LTA type zeolite frameworks." In Microporous and other Framework Materials with Zeolite-Type Structures, 479–83. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-54252-1_83.
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Baur, W. H., and R. X. Fischer. "Crystal structure and chemical composition of compounds with LTL type zeolite frameworks." In Microporous and other Framework Materials with Zeolite-Type Structures, 484–87. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-54252-1_84.
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Shen, Dekui, Chongbo Cheng, Nana Liu, and Rui Xiao. "Lignin Depolymerization (LDP) with Solvolysis for Selective Production of Renewable Aromatic Chemicals." In Production of Biofuels and Chemicals from Lignin, 289–320. Singapore: Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-1965-4_10.
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Hubený, I. "Model Atmospheres and Radiative Transfer in Chemically Peculiar Stars: Interpretational Significance of Non-LTE." In Upper Main Sequence Stars with Anomalous Abundances, 57–79. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4714-6_11.
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Rosca, Iosif D., Roham Mactabi, and Suong V. Hoa. "Influence of the Carbon Nanotube Type, Loading and Chemical Functionalization on the Fatigue Resistance of Aluminum Lap Joints." In ICAF 2011 Structural Integrity: Influence of Efficiency and Green Imperatives, 179–87. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-1664-3_14.
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Ma, Yunpeng. "Xixia Longcheng Special Materials Co., Ltd. v. Yulin Intellectual Property Bureau, Shenmu Tianyuan Chemical Co., Ltd. of Shaanxi Coal and Chemical Industry (Dispute over Administrative Resolution of Patent Rights): Identification and Resolution on Procedure Violations in Administrative Enforcement of Patent Law." In Library of Selected Cases from the Chinese Court, 337–45. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-15-9136-5_35.
Full textConference papers on the topic "Chemical LTP"
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Liu, Mingyan, Kwanghoon Baek, Fransico Argüelles Vivas, Gayan Aruna Abeykoon, and Ryosuke Okuno. "Effects of Surfactant Partitioning Coefficient and Interfacial Tension on the Oil Displacement in Low-Tension Polymer Flooding." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206220-ms.
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Abstract Complex surfactant formulations have been applied to generate an ultra-low interfacial tension (IFT) (e.g., 10-3 dyne/cm) between the displacing water phase and the displaced oil phase in chemical enhanced oil recovery (CEOR), where the residual oil after waterflooding can be largely recovered as an oil bank. This paper is concerned with a simpler, lower-cost CEOR, in which a sole additive of surface active solvent (SAS) makes low-tension displacement fronts in polymer flooding (e.g., 10-2 dyne/cm) without involving ultra-low IFT microemulsion phase behavior. The main objective of this research is to technically verify such low-tension polymer (LTP) flooding for a secondary-mode oil displacement through a sandpack of 9.5 Darcy. Previous research found that 2-ethylhexanol-7PO-15EO (2-EH-7PO-15EO, or "7-15") as SAS was able to reduce the IFT between polymer solution and the reservoir oil from 15.8 dyne/cm to 0.025 dyne/cm. In this research, the effect of SAS partition coefficient on LTP flooding was studied as an additional factor for SAS optimization. In particular, the comparison between two SAS species, 2-EH-4PO-15EO (4-15) and 2-EH-7PO-25EO (7-25), was important, because they had similar IFT values, but markedly different partition coefficients. The IFT was 0.18 dyne/cm with 4-15 and 0.20 dynes/cm with 7-25; and the partition coefficients were 1.61 with 4-15 and 0.68 with 7-25 at the experimental temperature, 61°C. These two SAS species were compared in secondary-mode LTP flooding with a slug of 0.5 wt% SAS for 0.5 pore-volumes injected (PVI). The oil recovery factor at 1.0 PVI was 65% with 4-15 and 67% with 7-25. At 5.0 PVI, it was 74% with 4-15 and 84% with 7-25. Although these two SAS species gave comparable IFT values, their oil-displacement efficiencies were quite different because 7-25 propagated more efficiently in the sandpack with the smaller partition coefficient. The smaller partition coefficient helped the SAS flow more efficiently in the aqueous phase with less retention in the remaining oil. Optimization of SAS likely requires taking a balance between lowering the partition coefficient and lowering the IFT. The SAS recovery at the effluent was 61% for the 4-15 SAS and 78% for the 7-25 SAS. The propagation of the 4-15 SAS was retarded approximately by 1.0 PVI in comparison to that of the 7-25 SAS. The adsorption of the 4-15 and 7-25 SAS were 0.019 mg/g sandpack and 0.020 mg/g sandpack. With a similar IFT reduction, the SAS with a smaller partition coefficient (i.e., 7-25) resulted in less retention, less retardation, and more oil production for a given amount of injection.
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Lakkaraju, H. S., D. S. Jebens, W. J. Borucki, and C. P. Mckay. "Time Resolved Spectra of Lightning Simulation in Titan's Atmosphere." In Laser Applications to Chemical Analysis. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/laca.1990.tuc4.
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We report, for the first time, time resolved spectroscopic measurements pertaining to the chemical evolution in a gas mixture reflecting the composition of Titan's atmosphere, under simulated lightning via Laser Induced Plasma (LIP)1.
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Wills, Kendall Scott. "Planar Deprocessing of Advanced VLSI Devices." In ISTFA 2006. ASM International, 2006. http://dx.doi.org/10.31399/asm.cp.istfa2006p0393.
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Abstract Modern day VLSI Semiconductor devices are manufactured using a chemical mechanical polish (CMP) process. The resultant layers are planar with respect to one another and should be easy to remove. All that needs to be done is to lap the layer until the region of interest is exposed. In practice this has been difficult. This article describes the combination of processes that are required to take full advantage of the strength of deprocessing techniques (lapping, plasma and gel controlled wet chemical deprocessing) to deliver a perfectly planar sample for inspection. A discussion on the thought process required to adequately select the proper chemicals for the gel controlled etch is given. Finally, a typical deprocessing flow is described. It is concluded that this combined solution enables planarity to be maintained across 100% of the device surface. There is less chance the failure site is damaged by the deprocessing.
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Hays, A. D., R. B. Husketh, and R. Burnham. "Chemically Pumped Nd:YAG Laser." In Advanced Solid State Lasers. Washington, D.C.: OSA, 1992. http://dx.doi.org/10.1364/assl.1992.lt3.
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Marikkar, Nuhuman, Matthieu Vierling, Maher Aboujaib, Richard Denolle, and Michel Moliere. "Soot Reduction in Gas Turbine Combustors Using Oxidation Catalyst Additives." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42067.
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The combustion of viscous ash forming fuels generates soot and ash that collectively form the so called particulate matter (PM). In addition to existing SOx and NOx emission regulations, the World Bank has enacted a 50 mg/Nm3 limit for the PM emissions of large combustion plants, creating a new challenge to power generators who use heavy fuel oils. LTL Holdings Ltd (Colombo, Sri Lanka) that own and operate a 300MW heavy-fueled gas turbine combined cycle (GTCC) at its Kerawalapitiya (Sri Lanka) power plant and GE Power & Water have embarked on a study intended to investigate the best PM abatement technique for heavy fueled gas turbines. This was done with TEKAT Ltd (London, UK) as the additive suppliers and the IRTES-LERMPS laboratory (Sévenans, France). In recent lab and field tests, the authors have thus evaluated the soot abatement capability of various combustion catalysts at different dosages. The results show that cerium proves an efficient oxidation catalyst in a real gas turbine, irrespective to its chemical form (Ce(III) or Ce(IV)), providing very substantial soot abatement rates. After briefly reviewing the different PM abatement techniques, the paper focuses on the lab and field tests performed and places emphasis on the performances of cerium in gas turbine combustors, along with the complex ash chemistry developed by heavy fuel oils.
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Czerwinski, John, Vijay K. Garikipati, Charlene N. Jones, Brad Pires, John P. Ludman, Debra H. McCauley, and Brian Linnemann. "A Collaborative Approach to Achieving a Gas-Tight Seal Using Expanded Polytetrafluorethylene (ePTFE) Gaskets in a Fiberglass-Reinforced Plastic (FRP) Lap-Joint Flanges." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78847.
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The work presented here is a collaborative approach to achieving a reliable gas tight seal in fiberglass reinforced plastic (FRP) flanged joints using expanded polytetrafluoroethylene (ePTFE) gaskets. There are many advantages to incorporating FRP flanged piping systems in today’s chemical process industry plant build. As regulations on reliability and fugitive emissions become stricter, it is more important than ever to eliminate possible damage and leak paths at the flanged connections in these systems. This paper details a case study on a collaboration between a chemical plant operator (end user), an ePTFE gasket manufacturer, and a FRP piping original equipment manufacturer. Over a twenty-four month period a FRP flanged system was designed and validated using a custom FRP stub and ring, also known as a lap joint, flange with an ePTFE gasket. The result was the development of a FRP bolted flange system that successfully achieved a reliable gas tight seal for aggressive chemicals. Beginning with a theoretical model and ending with experimental lab analyses, the conclusive results are included herein.
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Mlynczak, M. G. "A Technique to Infer the Heating Rate Associated With Non-LTE Processes in Upper Mesospheric and Lower Thermospheric Ozone." In Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1991. http://dx.doi.org/10.1364/orsa.1991.omb4.
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Non-LTE processes in ozone are significant components of the energy budget of the upper mesosphere and lower thermosphere [Mlynczak, 1991]. The exothermic recombination reaction that forms ozone and the upwelling radiation (from the vicinity of the stratopause) absorbed by ozone have the potential to heat the mesopause region (80-105 km) at rates exceeding 6K/day if all potential (radiative plus chemical) energy would be converted to heat. Calculation of the heating rate requires a detailed knowledge of the processes by which ozone exchanges internal energy with its environment through chemical, collisional, and radiative processes. At present, the knowledge of the rate coefficients describing the non-LTE processes is probably not sufficient to permit reliable calculations of the heating associated with non-LTE processes in ozone. Shown in Fig. 1 are the heating rates (in K day-l) calculated using two different models of non-LTE processes in ozone. The curve labeled "1" is the heating rate calculated using the model of Solomon et al. [1986] and the curve labeled "2" is the heating rate calculated using a model from Mlynczak and Dray son [1990a]. The two non-LTE models differ significantly in their parameterization of the non-LTE processes in ozone. In this paper, a technique whereby the heating rate may be inferred from appropriate measurements from satellite remote sensing instruments will be examined. This technique allows for the inference of the heating rate virtually independent of assumed kinetics models.
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Benter, Markus M., Ian G. Bywater, and Ken E. Scott. "Low Ash Fuel and Chemicals From the Convertech Process." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-351.
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A new, efficient process for reducing the ash content, drying and fractionating raw lignocellulosic materials into chemicals and a dry solid end product, eminently suitable as a fuel for conventional boilers or for milling to a fine powder for gas turbine firing, shows strong potential for renewable power generation. The dry, low ash solids, termed “Cellulig™”, will also be suitable for gasification and to drive gas turbines. Sustainable liquid and gaseous fuels will become increasingly necessary in the 21st century to reduce dependence on imported fuels, to replace dwindling supplies of oil and natural gas and to avoid environmental damage from green house gases. Convertech Group Ltd. has built a demonstration biomass processing plant at Burnham, Canterbury, New Zealand, with investment from the energy industry and the Australian Energy Research and Development Council. The essential chemical and process engineering elements are described and the current and future development opportunities outlined.
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Zhou, Nancy Chun, Meng Lu, Fuchen Liu, Wenhong Li, Jianshen Li, Steven Vaughan, Eric Trine, Zhitao Li, Matt Dean, and Chris Britton. "Development of the Surfactant-Based Chemical EOR Formula for Low Permeability Reservoirs." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207969-ms.
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Abstract Based on the results of the foam flooding for our low permeability reservoirs, we have explored the possibility of using low interfacial tension (IFT) surfactants to improve oil recovery. The objective of this work is to develop a robust low-tension surfactant formula through lab experiments to investigate several key factors for surfactant-based chemical flooding. Microemulsion phase behavior and aqueous solubility experiments at reservoir temperature were performed to develop the surfactant formula. After reviewing surfactant processes in literature and evaluating over 200 formulas using commercially available surfactants, we found that we may have long ignored the challenges of achieving aqueous stability and optimal microemulsion phase behavior for surfactant formulations in low salinity environments. A surfactant formula with a low IFT does not always result in a good microemulsion phase behavior. Therefore, a novel synergistic blend with two surfactants in the formulation was developed with a cost-effective nonionic surfactant. The formula exhibits an increased aqueous solubility, a lower optimum salinity, and an ultra-low IFT in the range of 10-4 mN/m. There were challenges of using a spinning drop tensiometer to measure the IFT of the black crude oil and the injection water at reservoir conditions. We managed the process and studied the IFTs of formulas with good Winsor type III phase behavior results. Several microemulsion phase behavior test methods were investigated, and a practical and rapid test method is proposed to be used in the field under operational conditions. Reservoir core flooding experiments including SP (surfactant-polymer) and LTG (low-tension-gas) were conducted to evaluate the oil recovery. SP flooding with a selected polymer for mobility control and a co-solvent recovered 76% of the waterflood residual oil. Furthermore, 98% residual crude oil recovery was achieved by LTG flooding through using an additional foaming agent and nitrogen. These results demonstrate a favorable mobilization and displacement of the residual oil for low permeability reservoirs. In summary, microemulsion phase behavior and aqueous solubility tests were used to develop coreflood formulations for low salinity, low temperature conditions. The formulation achieved significant oil recovery for both SP flooding and LTG flooding. Key factors for the low-tension surfactant-based chemical flooding are good microemulsion phase behavior, a reasonably aqueous stability, and a decent low IFT.
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Wang, Chenxi, Jikai Xu, Xiaorun Zeng, Yanhong Tian, Chunqing Wang, and Tadatomo Suga. "Low-temperature direct bonding of silicon to quartz glass wafer via sequential wet chemical surface activation." In 2017 5th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D). IEEE, 2017. http://dx.doi.org/10.23919/ltb-3d.2017.7947417.
Full textReports on the topic "Chemical LTP"
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Idakwo, Gabriel, Sundar Thangapandian, Joseph Luttrell, Zhaoxian Zhou, Chaoyang Zhang, and Ping Gong. Deep learning-based structure-activity relationship modeling for multi-category toxicity classification : a case study of 10K Tox21 chemicals with high-throughput cell-based androgen receptor bioassay data. Engineer Research and Development Center (U.S.), July 2021. http://dx.doi.org/10.21079/11681/41302.
Full textAbstract:
Deep learning (DL) has attracted the attention of computational toxicologists as it offers a potentially greater power for in silico predictive toxicology than existing shallow learning algorithms. However, contradicting reports have been documented. To further explore the advantages of DL over shallow learning, we conducted this case study using two cell-based androgen receptor (AR) activity datasets with 10K chemicals generated from the Tox21 program. A nested double-loop cross-validation approach was adopted along with a stratified sampling strategy for partitioning chemicals of multiple AR activity classes (i.e., agonist, antagonist, inactive, and inconclusive) at the same distribution rates amongst the training, validation and test subsets. Deep neural networks (DNN) and random forest (RF), representing deep and shallow learning algorithms, respectively, were chosen to carry out structure-activity relationship-based chemical toxicity prediction. Results suggest that DNN significantly outperformed RF (p < 0.001, ANOVA) by 22–27% for four metrics (precision, recall, F-measure, and AUPRC) and by 11% for another (AUROC). Further in-depth analyses of chemical scaffolding shed insights on structural alerts for AR agonists/antagonists and inactive/inconclusive compounds, which may aid in future drug discovery and improvement of toxicity prediction modeling.
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Sartain, Bradley, Kurt Getsinger, Damian Walter, John Madsen, and Shayne Levoy. Flowering rush control in hydrodynamic systems : part 1 : water exchange processes. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45425.
Full textAbstract:
In 2018, field trials evaluated water-exchange processes using rhodamine WT dye to provide guidance on the effective management of flowering rush (Butomus umbellatus L.) at McNary Dam and Reservoir (Wallula Lake, 15,700 ha). Additional evaluations determined the effectiveness of BubbleTubing (hereafter referred to as bubble curtain) at reducing water exchange within potential flowering rush treatment areas. Dye readings were collected from multiple sampling points at specific time intervals until a dye half-life could be determined. Whole-plot dye half-lives at sites without bubble curtain ranged 0.56–6.7 h. In slower water-exchange sites (≥2.6 h dye half-life), the herbicide diquat should have a sufficient contact time to significantly reduce flowering rush aboveground biomass. Other sites demonstrated very rapid water exchange (<1.5 h dye half-life), likely too rapid to effectively control flowering rush using chemical treatments without the use of a barrier or curtain to slow water exchange. At one site, the use of the bubble curtain increased the dye half-life from 3.8 h with no curtain to 7.6 and 7.1 h with a bubble curtain. The bubble curtain’s ability to slow water exchange will provide improved chemical control and in-crease the potential for other chemical products to be effectively used.
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Asenath-Smith, Emily, Emma Ambrogi, Lee Moores, Stephen Newman, and Jonathon Brame. Leveraging chemical actinometry and optical radiometry to reduce uncertainty in photochemical research. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42080.
Full textAbstract:
Subtle aspects of illumination sources and their characterization methods can introduce significant uncertainty into the data gathered from light-activated experiments, limiting their reproducibility and technology transition. Degradation kinetics of methyl orange (MO) and carbamazepine (CM) under illumination with TiO₂ were used as a case study for investigating the role of incident photon flux on photocatalytic degradation rates. Valerophenone and ferrioxalate actinometry were paired with optical radiometry in three different illumination systems: xenon arc (XE), tungsten halogen (W-H), and UV fluorescent (UV-F). Degradation rate constants for MO and CM varied similarly among the three light systems as k W-H < kiv-F < kXE, implying the same relative photon flux emission by each light. However, the apparent relative photon flux emitted by the different lights varied depending on the light characterization method. This discrepancy is shown to be caused by the spectral distribution present in light emission profiles, as well as absorption behavior of chemical actinometers and optical sensors. Data and calculations for the determination of photon flux from chemical and calibrated optical light characterization is presented, allowing us to interpret photo-degradation rate constants as a function of incident photon flux. This approach enabled the derivation of a calibrated ‘rate-flux’ metric for evaluating and translating data from photocatalysis studies.
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Glasscott, Matthew, Johanna Jernberg, Erik Alberts, and Lee Moores. Toward the electrochemical detection of 2,4-dinitroanisole (DNAN) and pentaerythritol tetranitrate (PETN). Engineer Research and Development Center (U.S.), March 2022. http://dx.doi.org/10.21079/11681/43826.
Full textAbstract:
Analytical methods to rapidly detect explosive compounds with high precision are paramount for applications ranging from national security to environmental remediation. This report demonstrates two proof-of-concept electroanalytical methods for the quantification of 2,4-dinitroanisol (DNAN) and pentaerythritol tetranitrate (PETN). For the first time, DNAN reduction was analyzed and compared at a bare graphitic carbon electrode, a polyaniline-modified (PANI) electrode, and a molecularly imprinted polymer (MIP) electrode utilizing PANI to explore the effect of surface-area and preconcentration affinity on the analytical response. Since some explosive compounds such as PETN are not appreciably soluble in water (<10 μg/L), necessitating a different solvent system to permit direct detection via electrochemical reduction. A 1,2-dichloroethane system was explored as a possibility by generating a liquid-liquid extraction-based sensor exploiting the immiscibility of 1,2-dichloroethane and water. The reduction process was explored using a scan rate analysis to extract a diffusion coefficient of 6.67 x 10⁻⁶ cm/s, in agreement with literature values for similarly structured nitrate esters. Once further refined, these techniques may be extended to other explosives and combined with portable electrochemical hardware to bring real-time chemical information to soldiers and citizens alike.
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Kontak, D. J., S. Paradis, Z. Waller, and M. Fayek. Petrographic, fluid inclusion, and secondary ion mass spectrometry stable isotopic (O, S) study of Mississippi Valley-type mineralization in British Columbia and Alberta. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/327994.
Full textAbstract:
A comprehensive study of Mississippi Valley-type base-metal deposits across the Canadian Cordillera was done to compare and contrast their features. Extensive dissolution of host rocks is followed by multiple generations of dolomite cements from early, low-temperature, fine-grained to coarser, higher temperature types that overlap with Zn-Pb sulfide minerals; late-stage calcite occludes residual porosity. Dolomite is generally chemically stoichiometric, but ore-stage types are often rich in Fe (&lt;1.3 weight per cent FeO) with small sphalerite inclusions. Sphalerite-hosted fluid inclusions record ranges for homogenization temperatures (77-214°C) and fluid salinity (1-28 weight per cent equiv. NaCl±CaCl2). These data suggest fluid mixing with no single fluid type related to all sulfide mineralization. In situ secondary ion mass spectrometry (SIMS) generated delta-18OVSMOW values for carbonate minerals (13-33 permille) reflect dolomite and calcite formation involving several fluids (seawater, basinal, meteoric) over a large temperature range at varying fluid-rock ratios. Sphalerite and pyrite SIMS delta-34SVCDT values vary (8-33 permille) but in single settings have small ranges (&lt;2-3 permille) that suggest sulfur was reduced via thermochemical sulfate reduction from homogeneous sulfur reservoirs. Collectively, the data implicate several fluids in the mineralizing process and suggest mixing of a sulfur-poor, metal-bearing fluid with a metal-poor, sulfide-bearing fluid.
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Amirav, Aviv, and Steven Lehotay. Fast Analysis of Pesticide Residues in Agricultural Products. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7695851.bard.
Full textAbstract:
The overall theme of this project was to increase the speed of analysis for monitoring pesticide residues in food. Traditionally, analytical methods for multiple pesticides are time-consuming, expensive, laborious, wasteful, and ineffective to meet critical needs related to food safety. Faster and better methods were needed to provide more cost-effective detection of chemical contaminants, and thus provide a variety of benefits to agriculture. This overarching goal to speed and improve pesticide analysis was successfully accomplished even beyond what was originally proposed by the investigators in 1998. At that time, the main objectives of this project were: 1) to further develop a direct sample introduction (DSI) device that enables fast sampling and introduction of blended-only agricultural products for analysis by gas chromatography (GC); 2) to evaluate, establish, and further develop the method of simultaneous pulsed flame photometric detector (PFPD) and mass spectrometry (MS) detection for enhanced pesticide identification capabilities; and 3) to develop a new and novel MS pesticide analysis method, based on the use of supersonic molecular beams (SMB) for sampling and ionization. The first and third objectives were successfully accomplished as proposed, and the feasibility of the second objective was already demonstrated. The capabilities of the GC/SMB-MS approach alone were so useful for pesticide analysis that the simultaneous use of a PFPD was considered superfluous. Instead, the PFPD was investigated in combination with an electron-capture detector for low-cost, simultaneous analysis of organophosphorus and organochlorine pesticides in fatty foods. Three important, novel research projects not originally described in the proposal were also accomplished: 1) development of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for pesticides in foods; 2) development and optimization of a method using low-pressure (LP) GC/MS to speed pesticide residue analysis; and 3) innovative application of analyte protectants to improve the GC analysis of important problematic pesticides. All of the accomplishments from this project are expected to have strong impact to the analytical community and implications to agriculture and food safety. For one, an automated DSI approach has become commercially available in combination with GC/MS for the analysis of pesticide residues. Meanwhile, the PFPD has become the selective detector of choice for the analysis of organophosphorus pesticides. Great strides were made in SMB-MS through the manufacture of a prototype "Supersonic GC/MS" instrument, which displayed many advantages over commercial GC/MS instruments. Most notably, the QuEChERS method is already being disseminated to routine monitoring labs and has shown great promise to improve pesticide analytical capabilities and increase lab productivity. The implications of these developments to agriculture will be to increase the percentage of food monitored and the scope of residues detected in the food, which will serve to improve food safety. Developed and developing countries alike will be able to use these methods to lower costs and improve results, thus imported/exported food products will have better quality without affecting price or availability. This will help increase trade between nations and mitigate certain disputes over residue levels in imported foods. The improved enforcement of permissible residue levels provided by these methods will have the effect to promote good agricultural practices among previously obstinate farmers who felt no repercussions from illegal or harmful practices. Furthermore, the methods developed can be used in the field to analyze samples quickly and effectively, or to screen for high levels of dangerous chemicals that may intentionally or accidentally appear in the food supply.
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Mueller, C., S. J. Piercey, M. G. Babechuk, and D. Copeland. Stratigraphy and lithogeochemistry of the Goldenville horizon and associated rocks, Baie Verte Peninsula, Newfoundland. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/328990.
Full textAbstract:
The Goldenville horizon in the Baie Verte Peninsula is an important stratigraphic horizon that hosts primary (Cambrian to Ordovician) exhalative magnetite and pyrite and was a chemical trap for younger (Silurian to Devonian) orogenic gold mineralization. The horizon is overlain by basaltic flows and volcaniclastic rocks, is intercalated with variably coloured argillites and cherts, and underlain by mafic volcaniclastic rocks; the entire stratigraphy is cut by younger fine-grained mafic dykes and coarser gabbro. Lithogeochemical signatures of the Goldenville horizon allow it to be divided into high-Fe iron formation (HIF; &gt;50% Fe2O3), low-Fe iron formation (LIF; 15-50% Fe2O3), and argillite with iron minerals (AIF; &lt;15% Fe2O3). These variably Fe-rich rocks have Fe-Ti-Mn-Al systematics consistent with element derivation from varying mineral contributions from hydrothermal venting and ambient detrital sedimentation. Post-Archean Australian Shale (PAAS)-normalized rare earth element (REE) signatures for the HIF samples have negative Ce anomalies and patterns similar to modern hydrothermal sediment deposited under oxygenated ocean conditions. The PAAS-normalized REE signatures of LIF samples have positive Ce anomalies, similar to hydrothermal sediment deposited under anoxic to sub-oxic conditions. The paradoxical Ce behaviour is potentially explained by the Mn geochemistry of the LIF samples. The LIF have elevated MnO contents (2.0-7.5 weight %), suggesting that Mn from hydrothermal fluids was oxidized in an oxygenated water column during hydrothermal venting, Mn-oxides then scavenged Ce from seawater, and these Mn-oxides were subsequently deposited in the hydrothermal sediment. The Mn-rich LIF samples with positive Ce anomalies are intercalated with HIF with negative Ce anomalies, both regionally and on a metre scale within drill holes. Thus, the LIF positive Ce anomaly signature may record extended and particle-specific scavenging rather than sub-oxic/redox-stratified marine conditions. Collectively, results suggest that the Cambro-Ordovician Taconic seaway along the Laurentian margin may have been completely or near-completely oxygenated at the time of Goldenville horizon deposition.
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Fallik, Elazar, Robert Joly, Ilan Paran, and Matthew A. Jenks. Study of the Physiological, Molecular and Genetic Factors Associated with Postharvest Water Loss in Pepper Fruit. United States Department of Agriculture, December 2012. http://dx.doi.org/10.32747/2012.7593392.bard.
Full textAbstract:
The fruit of pepper (Capsicum annuum) commonly wilts (or shrivels) during postharvest storage due to rapid water loss, a condition that greatly reduces its shelf life and market value. The fact that pepper fruit are hollow, and thus have limited water content, only exacerbates this problem in pepper. The collaborators on this project completed research whose findings provided new insight into the genetic, physiological, and biochemical basis for water loss from the fruits of pepper (Capsicum annuum and related Capsicum species). Well-defined genetic populations of pepper were used in this study, the first being a series of backcross F₁ and segregating F₂, F₃, and F₄ populations derived from two original parents selected for having dramatic differences in fruit water loss rate (very high and very low water loss). The secondly population utilized in these studies was a collection of 50 accessions representing world diversity in both species and cultivar types. We found that an unexpectedly large amount of variation was present in both fruit wax and cutin composition in these collections. In addition, our studies revealed significant correlations between the chemical composition of both the fruit cuticular waxes and cutin monomers with fruit water loss rate. Among the most significant were that high alkane content in fruit waxes conferred low fruit water loss rates and low permeability in fruit cuticles. In contrast, high amounts of terpenoids (plus steroidal compounds) were associated with very high fruit water loss and cuticle permeability. These results are consistent with our models that the simple straight chain alkanes pack closely together in the cuticle membrane and obstruct water diffusion, whereas lipids with more complex 3-dimensional structure (such as terpenoids) do not pack so closely, and thus increase the diffusion pathways. The backcross segregating populations were used to map quantitative trait loci (QTLs) associated with water loss (using DART markers, Diversity Arrays Technology LTD). These studies resulted in identification of two linked QTLs on pepper’s chromosome 10. Although the exact genetic or physiological basis for these QTLs function in water loss is unknown, the genotypic contribution in studies of near-isogenic lines selected from these backcross populations reveals a strong association between certain wax compounds, the free fatty acids and iso-alkanes. There was also a lesser association between the water loss QTLs with both fruit firmness and total soluble sugars. Results of these analyses have revealed especially strong genetic linkages between fruit water loss, cuticle composition, and two QTLs on chromosome 10. These findings lead us to further speculate that genes located at or near these QTLs have a strong influence on cuticle lipids that impact water loss rate (and possibly, whether directly or indirectly, other traits like fruit firmness and sugar content). The QTL markers identified in these studies will be valuable in the breeding programs of scientists seeking to select for low water loss, long lasting fruits, of pepper, and likely the fruits of related commodities. Further work with these newly developed genetic resources should ultimately lead to the discovery of the genes controlling these fruit characteristics, allowing for the use of transgenic breeding approaches toward the improvement of fruit postharvest shelf life.
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Shomer, Ilan, Ruth E. Stark, Victor Gaba, and James D. Batteas. Understanding the hardening syndrome of potato (Solanum tuberosum L.) tuber tissue to eliminate textural defects in fresh and fresh-peeled/cut products. United States Department of Agriculture, November 2002. http://dx.doi.org/10.32747/2002.7587238.bard.
Full textAbstract:
The project sought to understand factors and mechanisms involved in the hardening of potato tubers. This syndrome inhibits heat softening due to intercellular adhesion (ICA) strengthening, compromising the marketing of industrially processed potatoes, particularly fresh peeled-cut or frozen tubers. However, ICA strengthening occurs under conditions which are inconsistent with the current ideas that relate it to Ca-pectate following pectin methyl esterase (PME) activity or to formation of rhamnogalacturonan (RG)-II-borate. First, it was necessary to induce strengthening of the middle lamellar complex (MLX) and the ICA as a stress response in some plant parenchyma. As normally this syndrome does not occur uniformly enough to study it, we devised an efficient model in which ICA-strengthening is induced consistently under simulated stress by short-chain, linear, mono-carboxylic acid molecules (OAM), at 65 oC [appendix 1 (Shomer&Kaaber, 2006)]. This rapid strengthening was insufficient for allowing the involved agents assembly to be identifiable; but it enabled us to develop an efficient in vitro system on potato tuber parenchyma slices at 25 ºC for 7 days, whereas unified stress was reliably simulated by OAMs in all the tissue cells. Such consistent ICA-strengthening in vitro was found to be induced according to the unique physicochemical features of each OAM as related to its lipophilicity (Ko/w), pKa, protonated proportion, and carbon chain length by the following parameters: OAM dissociation constant (Kdiss), adsorption affinity constant (KA), number of adsorbed OAMs required for ICA response (cooperativity factor) and the water-induced ICA (ICAwater). Notably, ICA-strengthening is accompanied by cell sap leakage, reflecting cell membrane rupture. In vitro, stress simulation by OAMs at pH<pKa facilitated the consistent assembly of ICAstrengthening agents, which we were able to characterize for the first time at the molecular level within purified insoluble cell wall of ICA-strengthened tissue. (a) With solid-state NMR, we established the chemical structure and covalent binding to cell walls of suberin-like agents associated exclusively with ICA strengthening [appendix 3 (Yu et al., 2006)]; (b) Using proteomics, 8 isoforms of cell wall-bound patatin (a soluble vacuolar 42-kDa protein) were identified exclusively in ICA-strengthened tissue; (c) With light/electron microscopy, ultrastructural characterization, histochemistry and immunolabeling, we co-localized patatin and pectin in the primary cell wall and prominently in the MLX; (d) determination of cell wall composition (pectin, neutral sugars, Ca-pectate) yielded similar results in both controls and ICA-strengthened tissue, implicating factors other than PME activity, Ca2+ or borate ions; (e) X-ray powder diffraction experiments revealed that the cellulose crystallinity in the cell wall is masked by pectin and neutral sugars (mainly galactan), whereas heat or enzymatic pectin degradation exposed the crystalline cellulose structure. Thus, we found that exclusively in ICA-strengthened tissue, heat-resistant pectin is evident in the presence of patatin and suberinlike agents, where the cellulose crystallinity was more hidden than in fresh control tissue. Conclusions: Stress response ICA-strengthening is simulated consistently by OAMs at pH< pKa, although PME and formation of Ca-pectate and RG-II-borate are inhibited. By contrast, at pH>pKa and particularly at pH 7, ICA-strengthening is mostly inhibited, although PME activity and formation of Ca-pectate or RG-II-borate are known to be facilitated. We found that upon stress, vacuolar patatin is released with cell sap leakage, allowing the patatin to associate with the pectin in both the primary cell wall and the MLX. The stress response also includes formation of covalently bound suberin-like polyesters within the insoluble cell wall. The experiments validated the hypotheses, thus led to a novel picture of the structural and molecular alterations responsible for the textural behavior of potato tuber. These findings represent a breakthrough towards understanding of the hardening syndrome, laying the groundwork for potato-handling strategies that assure textural quality of industrially processed particularly in fresh peeled cut tubers, ready-to-prepare and frozen preserved products.
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Science, Fera. Analysis of CBD Products. Food Standards Agency, November 2022. http://dx.doi.org/10.46756/sci.fsa.cis490.
Full textAbstract:
The Food Standards Agency commissioned Fera Science Ltd. to carry out a survey to obtain a snapshot of CBD products on sale in England and Wales in order to inform FSA risk assessment of CBD products. Thirty CBD products were purchased from a range of online sellers from England and Wales. Samples comprised of two broad categories: oils and sprays, and edibles (including beverages). The sampling followed a scheme suggested by FSA. This is not a statistically representative sample of the market and instead provides a snapshot of the current market, to assist the design of future sampling and surveillance activity. There is the potential for residues of chemicals to be present in CBD products as a result of their natural occurrence in the raw material or arising from the manufacturing process, for example, mycotoxins, metals, pesticides, and the residues of solvents used to extract CBD. This study informs the FSA’s understanding of the type and levels of contaminants that may arise in CBD products. A wide range of analysis on CBD products was undertaken using accredited methods, for heavy metals, Polycyclic Aromatic Hydrocarbons (PAHs), pesticides, mycotoxins, CBD content and cannabinoid profiles. Analysis for residual solvents and additional mycotoxins was also carried out, but these were not accredited. The results of testing found the following: Heavy metals (cadmium, mercury & lead) and arsenic were not detected in the majority of samples, meaning levels were below the limits of quantification of the method. Seven samples contained lead, four samples arsenic and two samples contained cadmium. Mercury was not found in any sample. A definitive statement as to whether products exceed maximum levels cannot be made due to uncertainty as to whether products would be classified as a food (i.e. oil) or a food supplement. A low incidence of low levels of mycotoxins, with Fusarium mycotoxins found more frequently than aflatoxins and ochratoxin A, mostly at the methods reporting limit. Three samples were found to contain ochratoxin A at the methods reporting limit. A total of seven pesticide residues were found across all of the products (each product was tested for over 400 pesticides). There are no specific Maximum Residue Limits (MRL) for CBD products. One oil product was found to have PAHs above the regulated levels, if classed as a product for direct consumption. If classed as a food supplement the PAHs were within regulated levels. Three samples contained residual solvents. One product was over the MRL. Most products contained CBD close to the declared value. Two oils had substantially different levels than that declared (one higher and one lower). CBD was not detected in one of the drink products. These are potentially non-compliant with compositional and standards requirements. Delta 9-THC was detected in 87 % (26) of the samples analysed. Of these 40% (12) were found to have THC+ (the total sum of illicit cannabinoids in the product) above the 1mg threshold outlined in current Home Office guidance (Opens in a new window).