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1
Seager, C. H., R. A. Anderson, and J. K. G. Panitz. "The diffusion of hydrogen in silicon and mechanisms for “unintentional” hydrogenation during ion beam processing." Journal of Materials Research 2, no. 1 (February 1987): 96–106. http://dx.doi.org/10.1557/jmr.1987.0096.
Повний текст джерелаАнотація:
Experiments are described in which hydrogen is injected into silicon by various techniques and detected by the neutralization of boron acceptor sites. Wet chemical etching is shown to inject protons several microns in a few seconds; this experiment is used to set a lower limit on the diffusivity of hydrogen of ⋍2⊠10−11 cm2/s at 300 K, a number in reasonable agreement with prior estimates deduced by Van Wieririgen and Warmholtz from high-temperature permeation measurements. A number of experiments are reported to elucidate the mechanism for “unintentional” hydrogenation occurring during argon ion bombardment. The data suggest that this effect is caused by bombardment-induced injection of hydrogen from surface H2O/hydrocarbon contaminants.
2
Smagulova, Nazym, Zhaxyntay Kairbekov, and Gulsezim Yermekbayeva. "Obtaining coke of improved quality by hydro-gentrification of coal tar." MATEC Web of Conferences 340 (2021): 01034. http://dx.doi.org/10.1051/matecconf/202134001034.
Повний текст джерелаАнотація:
The catalytic properties of non-applied nickel-sulfide catalysts in the reactions of hydrogenation and hydrodesulphurization of coal tar from the coal semi-coking of the Shubarkul field (Republic of Kazakhstan) were studied to obtain data necessary for the intensification of the resin processing technology, increasing the yield and improving the quality of the resulting needle coke. As a feedstock, the resin was used without preliminary dehydration (water content 3.4 %) and distillation in a mixture with the prepared catalyst and the residue of distillation with boiling point above 320°C of oil from the Kumkol field (Republic of Kazakhstan), taken in a mass ratio of 1:1.
3
Flid, M. R., L. M. Kartashov, and Yu A. Treger. "Theoretical and Applied Aspects of Hydrodechlorination Processes—Catalysts and Technologies." Catalysts 10, no. 2 (February 11, 2020): 216. http://dx.doi.org/10.3390/catal10020216.
Повний текст джерелаАнотація:
The commercial implementation of hydrodechlorination processes will be an essential step in resolving the problem of environmentally sound organochlorine wastes processing. By now, there is a number of fundamental, applied, and process elaborations of such processes, in which chlorine is almost completely removed from wastes. The review article contains a significant number of results including basic regularities of thermal hydrodechlorination, comprehensive and selective catalytic hydrodechlorination. It discusses thermodynamics, kinetics, and catalysts of gas and liquid phase processes. Considerable attention is paid to hydrodechlorination of vinyl chloride production wastes and utilization of tetrachloromethane, which is the ozone-depleting substance. It also discusses hydrodechlorination of mono- and (poly)chlorobenzenes. The important examples of liquid phase data include hydrogenation using complex hydrides of elements. It also includes several flow sheets of hydrodechlorination processes.
4
Grundy, W. M., M. K. Bird, D. T. Britt, J. C. Cook, D. P. Cruikshank, C. J. A. Howett, S. Krijt, et al. "Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth." Science 367, no. 6481 (February 13, 2020): eaay3705. http://dx.doi.org/10.1126/science.aay3705.
Повний текст джерелаАнотація:
The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU69) has been largely undisturbed since its formation. We studied its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide–rich ice and/or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, which suggests that Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 kelvin.
5
Li, Luya, Yuting Chen, Xue Feng, Jintuo Yin, Shenghao Li, Yupeng Sun, and Lantong Zhang. "Identification of Metabolites of Eupatorin in Vivo and in Vitro Based on UHPLC-Q-TOF-MS/MS." Molecules 24, no. 14 (July 23, 2019): 2658. http://dx.doi.org/10.3390/molecules24142658.
Повний текст джерелаАнотація:
Eupatorin is the major bioactive component of Java tea (Orthosiphon stamineus), exhibiting strong anticancer and anti-inflammatory activities. However, no research on the metabolism of eupatorin has been reported to date. In the present study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) combined with an efficient online data acquisition and a multiple data processing method were developed for metabolite identification in vivo (rat plasma, bile, urine and feces) and in vitro (rat liver microsomes and intestinal flora). A total of 51 metabolites in vivo, 60 metabolites in vitro were structurally characterized. The loss of CH2, CH2O, O, CO, oxidation, methylation, glucuronidation, sulfate conjugation, N-acetylation, hydrogenation, ketone formation, glycine conjugation, glutamine conjugation and glucose conjugation were the main metabolic pathways of eupatorin. This was the first identification of metabolites of eupatorin in vivo and in vitro and it will provide reference and valuable evidence for further development of new pharmaceuticals and pharmacological mechanisms.
6
Anh, Hoang, Vera A. Kalashnikova, and Olga V. Lefedova. "KINETIC OF HYDROGENATION OF 4-NITRO-2'-HYDROXY-5'-METHYLAZOBENZEN ON SKELETAL NICKEL IN AQUEOUS SOLUTION OF 2-PROPANOL." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 61, no. 3 (February 27, 2018): 10. http://dx.doi.org/10.6060/tcct.20186103.5604.
Повний текст джерелаАнотація:
The article is devoted to the kinetics of hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene on skeletal nickel in an aqueous solution of 2-propanol with the azeotropic composition at various initial concentrations of the starting compound. According to the obtained dependences of hydrogen absorption during the process, the changes in the amounts of the initial 4-nitro-2'-hydroxy-5'-methylazobenzene, the processing of the kinetic curves in linear coordinates of different orders, the data on the material balance of reaction products, the conlusion is drawn that at low concentrations the hydrogen addition is carried out through the nitro and azo groups to the starting 4-nitro-2'-hydroxy-5'-methylazobenzene molecule. An increase in the initial amount of 4-nitro-2'-hydroxy-5'-methylazobenzene introduced into the reactor leads to a marked decrease in the content of 4-amino-2'-hydroxy-5'-methylazobenzene. It was experimentally established that at the low initial concentrations, hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzene on skeletal nickel in aqueous solution of 2-propanol with the azeotropic composition proceeds on the first order and zero one for hydrogen. An increase in the initial concentration of hydrogenated compound above the solubility limit leads to a sharp increase in a value of excessive adsorption of 4-nitro-2'-hydroxy-5'-methylazobenzene, to an increase in diffusion inhibition on hydrogen and to a change in the order for reducing agent. At the initial amounts of 4-nitro-2'-hydroxy-5'-methylazobenzene studied the transformation proceeds in two parallel directions. One of the directions is due to the addition of hydrogen on nitro groups to form 4-amino-2'-hydroxy-5'-methylazobenzene, and the second one on azo groups to form 2-amino-4-cresol and 4-nitroaniline.Forcitation:Hoang Anh, Kalashnikova V.A., Lefedova O.V. Kinetic of hydrogenation of 4-nitro-2'-hydroxy-5'-methylazobenzen on skeletal nickel in aqueous solution of 2-propanol. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 10-15
7
Leroux, Killian, Jean-Claude Guillemin, and Lahouari Krim. "Organic residues in astrophysical ice analogues: Thermal processing of hydrogenated glyoxal ices under interstellar conditions." Monthly Notices of the Royal Astronomical Society 504, no. 2 (April 14, 2021): 2181–89. http://dx.doi.org/10.1093/mnras/stab951.
Повний текст джерелаАнотація:
ABSTRACT Organic residues are considered as part of the chemical composition of the interstellar dust grains. They are formed under the extreme conditions of the interstellar medium and play an important role in exobiology. They may contain pre-biotic organic species such as amino acids, constituents of proteins and building blocks of DNA and RNA, key elements of life. By investigating the formation of organic residues in an astrophysical context, many groups have been focusing in the UV irradiation and subsequent warm-up of astrophysical ice analogues. This aims to suggest that organic residues are mainly formed in regions of molecular clouds exposed to UV light or cosmic rays. This study shows an organic residue formation involving glyoxal ice and H atoms. While the hydrogenation of glyoxal at 10 K leads mainly to small molecules such as CO and H2CO and CH3OH, we show that the heating of the hydrogenated ice in the 10–300 K temperature range leads to solid residues whose structure is similar to that of glycolaldehyde but they remain stable in solid phase at 300 K and atmospheric pressure. The analysis of the IR data shows that the organic residues formed through the thermal processing of CHOCHO + H reaction would be a mixture of hydroxypyruvaldehyde and methyl glyoxylate, two solid organics whose formation starts with an H-abstraction from glyoxal to form CHOCO• radical which recombines to •CH2OH and •OCH3 radicals. These latter may be formed and trapped in glyoxal ice as secondary products from H2CO + H secondary reaction.
8
Fan, Xiaoyong, Dong Li, Louwei Cui, Ruitian Shao, Chunran Chang, Long Yan, and Bo Yang. "Analysis of Distribution and Structures of Heteroatom Compounds in Asphaltene of Medium/Low Temperature Coal Tar by Negative Anion Mode ESI FT-ICR MS." Sustainability 14, no. 23 (November 22, 2022): 15497. http://dx.doi.org/10.3390/su142315497.
Повний текст джерелаАнотація:
The existence of heteroatomic compounds with complex structure and different polarity in the asphaltene of medium and low temperature coal tar (M/LTCT) limits its processing and utilization. Combined with negative ion electrospray ionization source (ESI), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize the molecular composition of O, N, and S heteroatom compounds in M/LTCT asphaltenes. Acidic oxygen-containing compounds (OCCs) and non-basic nitrogen-containing compounds (NCCs) in asphaltenes were identified, except for sulfur-containing compounds (SCCs). The mass spectra showed that the heteroatom compounds in asphaltene mainly existed as NX, N1OX, N2OX, N3OX, N4OX, N5OX, N6OX, and OX class species (where x = 1–6). The M/LTCT asphaltenes were enriched with O4, N4, and N1O1 class species. The core structure of O4 class species were likely to be composed of 1–7 aromatic rings with 4 phenolic hydroxyl groups, the core structure of N4 class species were likely to be comprised of 4–7 aromatic rings with a piperazine ring and a pyrazole ring, and the core structure of N1O1 was mainly 3–6 aromatic rings with a phenolic hydroxyl group and a pyrrole ring. These results suggest that more condensed NCCs and OCCs with short, substituted alky side chains are presented, which are more easily to undergo condensation to generate fused molecules, making it too difficult to be removed by hydrogenation. Through the analysis of the molecular structures of OCCs and non-basic NCCs in M/LTCT asphaltenes, important information about the molecular composition can be obtained, which can provide basic data for the hydrogenation of deasphaltene.
9
Le, Linh D., J. D. Tate, Mary Beth Seasholtz, Manish Gupta, Thomas Owano, Doug Baer, Trevor Knittel, Alan Cowie, and Jie Zhu. "Development of a Rapid On-Line Acetylene Sensor for Industrial Hydrogenation Reactor Optimization Using Off-Axis Integrated Cavity Output Spectroscopy." Applied Spectroscopy 62, no. 1 (January 2008): 59–65. http://dx.doi.org/10.1366/000370208783412654.
Повний текст джерелаАнотація:
A spectroscopic analyzer has been developed for rapid, accurate quantification of acetylene and methyl acetylene in hydrocarbon cracked gas processing plants. The system utilizes off-axis integrated output cavity spectroscopy to measure the near-infrared, cavity-enhanced absorption spectrum of ethylene, methyl acetylene, and acetylene and employs a chemometric data analysis strategy to quantify the respective constituents. Initial tests verified that the instrument is capable of measuring <0.050 ppmv of acetylene, has a precision of ±0.025 ppmv, and can accurately determine acetylene concentrations with comparable accuracy to a gas chromatograph (±0.1 ppmv) in an actual process stream composition matrix under plant operating conditions. Subsequently, the prototype analyzer was installed in a hydrocarbon facility for field-trials, where its rapid response (≤30 seconds or better) allowed it to measure transient acetylene and methyl acetylene fluctuations that were too fast for conventional methodologies. Moreover, the analyzer showed an extended dynamic range that enabled measurement of very high acetylene levels (0–1000 ppmv) during abnormal plant operations. Finally, two commercial acetylene analyzer systems with stream-switching capabilities were implemented in an industrial facility and initial results are presented.
10
Verevkin, Sergey P., Sergey P. Safronov, Artemiy A. Samarov, and Sergey V. Vostrikov. "Hydrogen Storage: Thermodynamic Analysis of Alkyl-Quinolines and Alkyl-Pyridines as Potential Liquid Organic Hydrogen Carriers (LOHC)." Applied Sciences 11, no. 24 (December 10, 2021): 11758. http://dx.doi.org/10.3390/app112411758.
Повний текст джерелаАнотація:
The liquid organic hydrogen carriers (LOHC) are aromatic molecules, which can be considered as an attractive option for the storage and transport of hydrogen. A considerable amount of hydrogen up to 7–8% wt. can be loaded and unloaded with a reversible chemical reaction. Substituted quinolines and pyridines are available from petroleum, coal processing, and wood preservation, or they can be synthesized from aniline. Quinolines and pyridines can be considered as potential LOHC systems, provided they have favorable thermodynamic properties, which were the focus of this current study. The absolute vapor pressures of methyl-quinolines were measured using the transpiration method. The standard molar enthalpies of vaporization of alkyl-substituted quinolines and pyridines were derived from the vapor pressure temperature dependencies. Thermodynamic data on vaporization and formation enthalpies available in the literature were collected, evaluated, and combined with our own experimental results. The theoretical standard molar gas-phase enthalpies of formation of quinolines and pyridines, calculated using the quantum-chemical G4 methods, agreed well with the evaluated experimental data. Reliable standard molar enthalpies of formation in the liquid phase were derived by combining high-level quantum chemistry values of gas-phase enthalpies of formation with experimentally determined enthalpies of vaporization. The liquid-phase hydrogenation/dehydrogenation reaction enthalpies of alkyl-substituted pyridines and quinolines were calculated and compared with the data for other potential liquid organic hydrogen carriers. The comparatively low enthalpies of reaction make these heteroaromatics a seminal LOHC system.
11
Nechaev, Yury S., Evgeny A. Denisov, Alisa O. Cheretaeva, Nadezhda A. Shurygina, Ekaterina K. Kostikova, Andreas Öchsner, and Sergei Yu Davydov. "On the Problem of “Super” Storage of Hydrogen in Graphite Nanofibers." C 8, no. 2 (March 29, 2022): 23. http://dx.doi.org/10.3390/c8020023.
Повний текст джерелаАнотація:
This article is devoted to some fundamental aspects of “super” storage in graphite nanofibers (GNF) of “reversible” (~20–30 wt.%) and “irreversible” hydrogen (~7–10 wt.%). Extraordinary results for hydrogen “super” storage were previously published by the group of Rodriguez and Baker at the turn of the century, which been unable to be reproduced or explained in terms of physics by other researchers. For the first time, using an efficient method of processing and analysis of hydrogen thermal desorption spectra, the characteristics of the main desorption peak of “irreversible” hydrogen in GNF were determined: the temperature of the highest desorption rate (Tmax = 914–923 K), the activation energy of the desorption process (Q ≈ 40 kJ mol−1), the pre-exponential rate constant factor (K0 ≈ 2 × 10−1 s−1), and the amount of hydrogen released (~8 wt.%). The physics of hydrogen “super” sorption includes hydrogen diffusion, accompanied by the “reversible” capture of the diffusant by certain sorption “centers”; the hydrogen spillover effect, which provides local atomization of gaseous H2 during GNF hydrogenation; and the Kurdjumov phenomenon on thermoelastic phase equilibrium. It is shown that the above-mentioned extraordinary data on the hydrogen “super” storage in GNFs are neither a mistake nor a mystification, as most researchers believe.
12
Singh, Kunal, Ruchika Nandha, and Savita Prashar. "A cross-sectional study to estimate the knowledge and practices regarding transfats among Panjab University students, Chandigarh." International Journal Of Community Medicine And Public Health 10, no. 1 (December 29, 2022): 218. http://dx.doi.org/10.18203/2394-6040.ijcmph20223547.
Повний текст джерелаАнотація:
Background: Transfats also infamous as ugly fat is unsaturated fat which is formed in industries by hydrogenation of monosaturated fat by thermal processing etc. to make cheaper plant fat look like animal fat. Various organizations like FSSAI have given guidelines on transfats. WHO has committed to removing industrially produced transfats by 2023.Objectives of current study were to estimate the knowledge and practices about transfats among university students and do a comparative analysis of knowledge and practices about transfats among different groups of university students.Methods: The study was conducted at Panjab university. Total N=362. Data were analyzed and comparison was done on basis of gender, educational level, place of stay, and family income.Results: 72% students had knowledge regarding transfats, males (73%) had more knowledge than females (70%) (r=-0.09, p<0.05). Hostellers (85%) had more knowledge than day scholars (75%) and students staying in rented accommodation (60%) regarding transfats (r=-0.015, p<0.05), 58% students had good practices while remaining 42% lack good practices regarding transfats, students in rented accommodation (64%) had better practices than day scholars (32%) and hostellers (43%) regarding transfats (r=0.028, p<0.05).Conclusions: It was found youth lack awareness and knowledge (28%) regarding transfats, had wrong practices (42%) regarding transfats and the adoption of food containing transfats among youth is common.
13
Melnikov, Evgeny, Galina Maier, Valentina Moskvina, and Elena Astafurova. "Influence of hydrogen saturation on the structure and mechanical properties of Fe-17Cr-13Ni-3Mo-0.01C austenitic steel during rolling at different temperatures." Metal Working and Material Science 23, no. 2 (June 10, 2021): 81–97. http://dx.doi.org/10.17212/1994-6309-2021-23.2-81-97.
Повний текст джерелаАнотація:
Introduction. The development of hydrogen energy implies a decrease in the dependence of various human activities on fossil energy sources and a significant reduction in carbon dioxide emission into the atmosphere. Therefore, the requirements for the quality of structural materials, which have the prospect of being used for storage and transportation of hydrogen, as well as for the creation of infrastructure facilities for hydrogen energy, are increasing. Therefore, the scientific researches on the hydrogen-assisted microstructure and mechanical behavior of structural materials in various loading schemes are of great importance. The aim of this work is to establish the effect of chemical-deformation treatment, including rolling combined with hydrogen saturation, on the microstructure, phase composition, and mechanical properties of 316L-type austenitic stainless steel. Methods. Transmission electron microscopy and backscattered electron diffraction, X-ray diffraction, X-ray phase and magnetic phase analysis, microindentation and uniaxial static tension are utilized. Results and Discussion. It is shown experimentally that after rolling with 25 and 50 % upset, the morphology of the defect structure and the phase composition of 316L steel substantially depends on the deformation temperature (at room temperature or with the cooling of the samples in the liquid nitrogen) and on hydrogen saturation rate (for 5 hours at a current density of 200 mA/cm2). The main deformation mechanisms of the steel in rolling are slip, twinning, and microlocalization of plastic flow, which all provide the formation of ultrafine grain-subgrain structure in the samples. In addition, deformation-induced ε and α' martensitic phases are formed in the structure of the rolled samples. Regardless of the regime of chemical-deformation processing, grain-subgrain structures with a high density of deformation defects are formed in steel, but its morphologies are dependent on the processing regime. The experimental data indicate that both preliminary hydrogen saturation and a decrease in the deformation temperature contribute to the more active development of mechanical twinning and deformation-induced phase transformations during rolling. Despite the discovered effects on the influence of hydrogen saturation on the deformation mechanisms and the morphology of a defective microstructure formed during rolling, preliminary hydrogenation has little effect on the mechanical properties of steel at a fixed degree and temperature of deformation. These data indicate that irrespective of the morphology of the defective grain-subgrain structure, grain refinement, accumulation of deformation defects and an increase in internal stresses lead to an increase in the strength characteristics of the steel.
14
Zaitsev, I. O., A. S. Levytskyi, and V. E. Sydorchuk. "AIR GAP CONTROL SYSTEM FOR HYDROGENERATORS." Devices and Methods of Measurements 8, no. 2 (June 9, 2017): 122–30. http://dx.doi.org/10.21122/2220-9506-2017-8-2-122-130.
Повний текст джерелаАнотація:
In this paper, we report of the solving the actual problem of control the air gap in the hydrogenerators. The aim of the study was development of a computerized information-measuring system for measuring the air gap in the hydrogenator, which used two capacitive sensors with parallel coplanar electrodes, and the method of determining the shape of the envelope parameters hydrogenerator rotor poles relative to the center axis of rotation, using the measurement results of the air gap.In practical studies of the sensor circuit it has been shown that its use allows for the informative value of the sensor capacitance conversion function to obtain a high accuracy and resolution measurement with digital linearization of converting function of the sensor with use program utility. To determine the form deviations of the envelope line of the rotor pole from the ideal cylinder, which is one of the main structural defects of the technological errors as results the distortion of the shape of the air gap in the hydrogenator, when the machine was manufacture and assembly. It is proposed to describe the shape of the envelope to use a Fourier transform. Calculation of the coefficients of the Fourier series is performed using the method of least squares as the regression coefficients.Application of this method in processing the measuring data in a computerized information-measuring system the developed with the primary converter with coplanar parallel electrodes allowed attaining the high measurement accuracy and resolution informative in magnitude of the capacity.
15
Ready, S. E., J. B. Boyce, D. K. Fork, P. Mei, G. B. Anderson, and R. I. Johnson. "Temperature Dependence of the Hall Mobility in Polycrystalline Silicon." MRS Proceedings 297 (January 1, 1993). http://dx.doi.org/10.1557/proc-297-545.
Повний текст джерелаАнотація:
Crystallization of amorphous silicon thin films by various methods has fostered enhancements in the electrical characteristics over their amorphous counterparts. For example, carrier mobilities ranging from 10 to >100 cm2/V-sec have been reported for laser crystallized films. The rather large variability of the transport characteristics with crystallization processing conditions is not well understood and, as a result, greatly complicates device process debugging. In addition, while it is generally believed that defects inherent in the grain boundaries provide the primary barriers degrading transport properties relative to single crystal silicon, the specific nature of these defects is not known. In this paper, we present data on the temperature dependence of the Hall mobility of thin silicon films crystallized by thermal and excimer laser processing. Hall data for the laser-crystallized phosphorus-doped material show a temperature dependence which differs dramatically from that for thermally crystallized materials, while the effects of hydrogenation are similar, reducing the barriers at the grain boundaries.
16
Tadepalli, Sunitha, and Adeniyi Lawal. "The Catalytic Hydrogenation of Aromatic Nitro Ketone in a Microreactor: Reactor Performance and Kinetic Studies." International Journal of Chemical Reactor Engineering 6, no. 1 (January 3, 2009). http://dx.doi.org/10.2202/1542-6580.1766.
Повний текст джерелаАнотація:
Catalytic hydrogenation of nitro aromatics is an important class of reactions in the pharmaceutical and fine chemical industries. These reactions are extremely fast and highly exothermic in nature; hence, mass and heat transfer limitations play an important role when these reactions are conducted in conventional batch reactors. The use of a micro-channel reactor for such reactions provides improved mass transfer rates which may ensure that the reaction operates close to intrinsic kinetics. In the present study, the hydrogenation of a model aromatic nitro ketone was conducted in a packed-bed microreactor. The effects of different processing conditions were studied using 5%Pd/Alumina catalyst, viz.: hydrogen pressure, substrate concentration, temperature, and residence time on the conversion of substrate, Space Time Yield (STY), and selectivity of product. Internal and external mass and heat transfer limitations in the microreactor were examined. The kinetic study was undertaken in a differential reactor mode, keeping the conversion of the reactant at less than 10%. The overall reaction was treated as comprising two separate reactions: first, the reduction of the nitro compound to hydroxylamine and then, the reduction of the hydroxylamine to amine. Two rate equations for the two consecutive reactions assuming the Langmuir-Hinshelwood mechanism provided the best fit to the experimental data. These two rate equations predicted the experimental rates satisfactorily and the differences were within 10% error. Experiments were also carried out in an integral reactor, and the reactor performance data were found to be in agreement with the predictions of the theoretical models.
17
Khan, Babar A., and Ranjana Pandya. "Thickness Effects on the Activation Energy of Source-Drain Current in P and N Channel Polycrystalline Silicon Thin Film Transistors." MRS Proceedings 182 (1990). http://dx.doi.org/10.1557/proc-182-347.
Повний текст джерелаАнотація:
AbstractWe report activation energy measurements of the source-drain current of polysilicon thin film transistors (TFTs). We have shown earlier that measurements carried out on unhydrogenated TFTs can be explained by the presence of band tail states in addition to deep localized states. After hydrogenation, the density of band tail states is greatly reduced and the data can be fitted with only the deep states.In the present work we have studied both n and p channel TFTs. This was done by measuring both type of devices on the same wafer so that differences due to processing conditions could be ruled out. Both type of devices had intentionally undoped channels and were identical except for the n or p type source-drain regions. The thinner TFTs discussed in this work have a sharper drop in the activation energy than would be expected from idealized calculations. This sharp drop in activation energy is also an indication of a sharp subthreshold slope. This decrease in subthreshold slope (Volts/decade) is due to the complete depletion of the channel polysilicon, which leads to a rapid increase (or decrease) in the surface potential as a function of the gate voltage.
18
Huybrechts, Inge, Fernanda Rauber, Geneviève Nicolas, Corinne Casagrande, Nathalie Kliemann, Roland Wedekind, Carine Biessy, et al. "Characterization of the degree of food processing in the European Prospective Investigation into Cancer and Nutrition: Application of the Nova classification and validation using selected biomarkers of food processing." Frontiers in Nutrition 9 (December 16, 2022). http://dx.doi.org/10.3389/fnut.2022.1035580.
Повний текст джерелаАнотація:
BackgroundEpidemiological studies have demonstrated an association between the degree of food processing in our diet and the risk of various chronic diseases. Much of this evidence is based on the international Nova classification system, which classifies food into four groups based on the type of processing: (1) Unprocessed and minimally processed foods, (2) Processed culinary ingredients, (3) Processed foods, and (4) “Ultra-processed” foods (UPF). The ability of the Nova classification to accurately characterise the degree of food processing across consumption patterns in various European populations has not been investigated so far. Therefore, we applied the Nova coding to data from the European Prospective Investigation into Cancer and Nutrition (EPIC) in order to characterize the degree of food processing in our diet across European populations with diverse cultural and socio-economic backgrounds and to validate this Nova classification through comparison with objective biomarker measurements.MethodsAfter grouping foods in the EPIC dataset according to the Nova classification, a total of 476,768 participants in the EPIC cohort (71.5% women; mean age 51 [standard deviation (SD) 9.93]; median age 52 [percentile (p)25–p75: 58–66] years) were included in the cross-sectional analysis that characterised consumption patterns based on the Nova classification. The consumption of food products classified as different Nova categories were compared to relevant circulating biomarkers denoting food processing, measured in various subsamples (N between 417 and 9,460) within the EPIC cohort via (partial) correlation analyses (unadjusted and adjusted by sex, age, BMI and country). These biomarkers included an industrial transfatty acid (ITFA) isomer (elaidic acid; exogenous fatty acid generated during oil hydrogenation and heating) and urinary 4-methyl syringol sulfate (an indicator for the consumption of smoked food and a component of liquid smoke used in UPF).ResultsContributions of UPF intake to the overall diet in % grams/day varied across countries from 7% (France) to 23% (Norway) and their contributions to overall % energy intake from 16% (Spain and Italy) to >45% (in the UK and Norway). Differences were also found between sociodemographic groups; participants in the highest fourth of UPF consumption tended to be younger, taller, less educated, current smokers, more physically active, have a higher reported intake of energy and lower reported intake of alcohol. The UPF pattern as defined based on the Nova classification (group 4;% kcal/day) was positively associated with blood levels of industrial elaidic acid (r = 0.54) and 4-methyl syringol sulfate (r = 0.43). Associations for the other 3 Nova groups with these food processing biomarkers were either inverse or non-significant (e.g., for unprocessed and minimally processed foods these correlations were –0.07 and –0.37 for elaidic acid and 4-methyl syringol sulfate, respectively).ConclusionThese results, based on a large pan-European cohort, demonstrate sociodemographic and geographical differences in the consumption of UPF. Furthermore, these results suggest that the Nova classification can accurately capture consumption of UPF, reflected by stronger correlations with circulating levels of industrial elaidic acid and a syringol metabolite compared to diets high in minimally processed foods.
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Cui Zi-Chun, Yang Mo-Han, Ruan Xiao-Peng, Fan Xiao-Li, Zhou Feng, and Liu Wei-Min. "High-throughput calculation of interfacial friction of two-dimensional materials." Acta Physica Sinica, 2023, 0. http://dx.doi.org/10.7498/aps.72.20221676.
Повний текст джерелаАнотація:
Friction generally happens during relative motion or the tendency of relative motion at the contacting interface, impeding the relative motion and consuming extra energy. Micro-scale friction shows difference to the macro-scale friction due to surface effects and other factors, It is necessary to study the friction behavior at nano-scale. First-principles method is an important way to study and understand friction at nano-scale. Nevertheless, constructing nearly a thousand models and the processing of a large number of data is very time consuming. In this paper, we have established a high-throughput computational program based on the first-principles method to study the interfacial friction of two-dimensional materials. The program realizes modeling, submitting computation tasks, multi-task concurrent calculation, data collection and processing, and image rendering of calculation results. All of these are done in batch automatically, which greatly saves researchers' time. In this paper, this program is used to simulate the normal load by changing the distance between layers and calculate the potential energy surface of BN/BN and graphene/graphene bilayer sliding systems at series interlayer distances, as well as the interlayer friction force and friction coefficient. The study found that with the decrease of the interlayer distance, the averaged friction force at BN/BN interface increases approximately linearly, and the friction coefficient was 0.11 ~ 0.17. The friction force at graphene/graphene interface firstly increases, then decreases, and then increases again. The friction coefficient reaches a minimum value (0.014) under a load of 12 nN, and these results are consistent with the previous results, verifying the reliability of the calculation program. In addition, we investigated the effect of surface hydrogenation and fluorination on the tribological property of the BN bilayer and found that the friction at the fluorinated BN/BN interface is reduced attributed to the smaller charge transfer at interface. Although the high-throughput calculation method realizes the automation and high-throughput calculation of tribological property at solid interface, there are still some limitations. First of all, the effect of interlaminar bending is not considered in the process of interlaminar relative sliding. secondly, the essence of the calculation result is static friction, not dynamic friction. In addition, the method does not consider the influence of temperature.
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"Final Report on the Safety Assessment of Lard Glyceride, Hydrogenated Lard Glyceride, Lard Glycerides, Hydrogenated Lard Glycerides, Lard, and Hydrogenated Lard." International Journal of Toxicology 20, no. 2_suppl (January 2001): 57–64. http://dx.doi.org/10.1080/109158101174381.
Повний текст джерелаАнотація:
Lard obtained from the rendering of fatty porcine tissue is used in cosmetic products, as are several of its derivatives. These derivatives include Lard Glycerides (mono-, di-, and triglycerides derived from Lard), Lard Glyceride (the monoglycerides only), Hydrogenated Lard Glycerides, Hydrogenated Lard Glyceride, and Hydrogenated Lard. The latter three are produced by controlled hydrogenation of the described precursor. These ingredients function as skin-conditioning agents and, with the exception of Lard, as viscosity-increasing agents in several cosmetic products. No information was available regarding the fate during processing of impurities such as pesticides or heavy metals that may be found in animal tissue. Lard itself is established by the Food and Drug Administration (FDA) as a GRAS (generally recognized as safe) substance. Animal studies report adverse effects expected with the feeding of high fat diets, but other animal toxicity data were not available. Lard was not mutagenic in transgenic mice. Cell proliferation assays showed more proliferation in mice fed Lard compared to those fed plant-source fats, but another study showed no difference. Cocarcinogenic effects were observed when high-fat diets containing Lard were fed, with known carcinogens, to mice, rats, and hamsters. Consistent with the FDA GRAS determination, it was concluded that these ingredients may be used safely in cosmetic formulations. However, it was considered important to limit the presence of heavy metals and/or polychlorinated biphenyl (PCB) or other pesticide contamination. Accordingly, limits were established as follows: lead, not more than 0.1 ppm; arsenic (as As), ≤ 3 ppm; mercury (as Hg), ≤ 1 ppm; and total PCB/pesticide contamination, not more than 40 ppm, with not more than 10 ppm for any specific residue.
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Рокосов, Ю. В., Н. Н. Рокосова, П. В. Горюнова, В. Ю. Рокосова, and Т. А. Романова. "STUDY OF THE CONTENT AND GENESIS OF ALKYL-SUBSTITUTED INDANES IN THE COMPOSITION OF THERMOHYDROLYSATE OF KAYCHAK COALS OF KUZBASS." Естественные и технические науки, no. 5(168) (June 10, 2022). http://dx.doi.org/10.25633/etn.2022.05.15.
Повний текст джерелаАнотація:
Термогидролиз гумусовых углей – одно из перспективных направлений их глубокой переработки. При этом возникает задача идентификации и количественного определения основных компонентов в термогидролизатах, решение которой возможно только с использованием методов хромато-масс-спектрометрии. С учетом закономерностей фрагментации углеводородов при ионизации электронным ударом, исследован состав термогидролизата кайчакских гумусовых углей Кузбасса на предмет содержания и генезиса алкилзамещенных инданов. Исследована гексановая фракция термогидролизата. Индивидуальные соединения и их гомологи идентифицировали по масс-спектрам с использованием базы данных NIST-11 и информационно-поисковых программ AMDIS и ChemStation. Итогом исследования являются данные, подтверждающие гипотезу существования закономерных связей между содержанием алкилинданов в продуктах термогидролиза гумусовых углей и наличием алкилнафталинов в составе термогидролизатов. Судя по наличию в термогидролизатах алкилзамещенных дигидро- и тетрагидронафталинов, которые следует рассматривать в качестве промежуточных продуктов гидрирования алкилнафталинов, в условиях термогидролиза гумусовых углей (гумитов) реализуется путь изомеризации алкилтетралинов в алкилинданы. Проведенное исследование позволило предположить, что, как и в случае гумитов, в условиях термогидролиза сапропелитов реализуется тот же путь изомеризации алкилтетралинов в алкилинданы наряду с механизмом образования этих соединений посредством термической деструкции высокомолекулярного органического вещества (сапропелитового керогена), изначально содержащего алкилароматические фрагменты с индановыми, тетралиновыми и нафталиновыми структурами. Thermohydrolysis of humus coals is one of the promising areas of their deep processing. In this case, the problem of identification and quantitative determination of the main components in thermohydrolysates arises, the solution of which is possible only with the use of gas chromatography-mass spectrometry methods. Taking into account the regularities of the fragmentation of hydrocarbons during ionization by electron impact, the composition of thermohydrolyzate of the Kaychak humus coals of Kuzbass was investigated for the content and genesis of alkyl-substituted indanes. The hexane fraction of the thermohydrolyzate was investigated. Individual compounds and their homologues were identified by mass spectra using the NIST-11 database and the AMDIS and ChemStation information retrieval programs. The result of the study is data confirming the hypothesis of the existence of regular relationships between the content of alkylindanes in the products of thermohydrolysis of humus coals and the presence of alkylnaphthalenes in the composition of thermohydrolyzates. Judging by the presence of alkyl-substituted tetralines (dihydro- and tetrahydronaphthalenes) in thermohydrolyzates, which should be considered as intermediate hydrogenation products of alkylnaphthalenes, under the conditions of thermohydrolysis of humus coals (humites), the path of isomerization of alkyltetralines to alkylindanes is realized. The study made it possible to assume that, as in the case of humites, under the conditions of thermohydrolysis of sapropelites, the same pathway of isomerization of alkyltetralines to alkylindanes is realized along with the mechanism of the formation of these compounds through the thermal destruction of high-molecular organic matter (sapropelite kerogen), which initially contains alkylaromatic fragments with indane and naphthalene structures.