Artículos de revistas: "H2OFVG"

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Hằng, Mai Thị, Nguyễn Thị Minh Nguyệt, Nguyễn Anh Tiến, Lê Văn Thăng, Vương Vĩnh Đạt y Trần Đức Châu. "TỔNG HỢP VẬT LIỆU NANO COMPOSITE CẤU TRÚC LỚP MoS2/SWNTs BẰNG PHƯƠNG PHÁP VI SÓNG". Tạp chí Khoa học 15, n.º 9 (8 de abril de 2020): 95. http://dx.doi.org/10.54607/hcmue.js.15.9.2642(2018).

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Vật liệu nano composite cấu trúc lớp MoS2/SWNTs – một vật liệu anode tiềm năng cho pin lithium ion – đã được tổng hợp thành công bằng phương pháp vi sóng thông qua phản ứng trực tiếp giữa các tiền chất. Tính chất vật liệu nano composite được đánh giá bằng các phương pháp phân tích: XRD, Raman, SEM, TEM… Kết quả phân tích bằng giản đồ XRD vật liệu tổng hợp với tỉ lệ thể tích SWNTs/H2O:EG = 1:30 thể hiện mũi đặc trưng cho MoS2 và SWNTs và chứng tỏ được sự hình thành liên kết giữa MoS2 và SWNTs. Phổ Raman cũng chứng tỏ được sự tồn tại của các pha 2H-/1T-MoS2. Bên cạnh đó, ảnh SEM và TEM cho thấy các cụm MoS2 (kích thước hạt từ 8-20 nm) dạng lục giác bám trên cấu trúc của SWNTs và phân bố xen kẽ trong khối vật liệu, giúp tăng tính năng của MoS2/SWNTs khi ứng dụng làm vật liệu anode của pin lithium ion.

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Baez, Marcos, Roland Vernet y Jacques Castanet. "Comparative water flux and daily energy expenditure of lizards of the genus Gallotia (Lacertidae) from the Canary Islands". Amphibia-Reptilia 16, n.º 1 (1995): 55–66. http://dx.doi.org/10.1163/156853895x00190.

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AbstractWater fluxes and daily energy expenditure (DEE) of Gallotia galloti, G. stehlini and G. atlantica, were estimated over a three-year period using the doubly-labelled water (DLW) method. Water influx varied little between seasons and between sexual categories. Juveniles tended to have higher water fluxes in spring in all three species; after a dry period the water turnover tended to decrease for all sexes in G. galloti and G. stehlini, whereas little variation was observed for G. atlantica. The average water influx, combined for all periods, was 46.27, 50.97 and 38.20 ml H2O.kg-1 d-1 for the three species respectively; only the last value differs significantly from the remaining two. The mean DEE, for all periods combined, were 189.7, 179.4 and 146.5 J g-1 d-1 for the three species respectively. As for water turnover, only the value for G. atlantica differed significantly. These data suggest that: G. atlantica may be better adaptated to maintain homeostasis during dry periods and that differences in interspecific DEE can also be explained by others factors than differences in habitat, climatic conditions, daily profiles of activity or body temperatures. We suspect that the incidence of intraspecific competition has more importance in G. atlantica than in the two other species.

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Palm, U., W. Boemke y H. W. Reinhardt. "Rhythmicity of urinary sodium excretion, mean arterial blood pressure, and heart rate in conscious dogs". American Journal of Physiology-Heart and Circulatory Physiology 262, n.º 1 (1 de enero de 1992): H149—H156. http://dx.doi.org/10.1152/ajpheart.1992.262.1.h149.

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The existence of urinary excretion rhythms in dogs, which is a matter of controversy, was investigated under strictly controlled intake and environmental conditions. In seven conscious dogs, 14.5 mmol Na, 3.55 mmol K, and 91 ml H2O.kg body wt-1.24 h-1 were either administered with food at 8:30 A.M. or were continuously infused at 2 consecutive days. During these 3 days, automatized 20-min urine collections, mean arterial blood pressure (MABP), and heart rate (HR) recordings were performed without disturbing the dogs. Fundamental and partial periodicities, the noise component of urinary sodium excretion (UNaV), MABP, and HR were analyzed using a method derived from Fourier and Cosinor analysis. Oral intake (OI) leads to powerful 24-h periodicities in all dogs and seems to synchronize UNaV. UNaV on OI peaked between 1 and 3 P.M. Under the infusion regimen, signs of nonstationary rhythms and desynchronization predominated. UNaV under the infusion regimen could be separated into two components: a rather constant component continuously excreted and superimposed to this an oscillating component. No direct coupling between UNaV and MABP periodicities could be demonstrated. On OI, an increase in HR seems to advance the peak UNaV in the postprandial period. HR and MABP signals were both superimposed with noise. We conclude that UNaV rhythms are present in dogs. They are considerably more pronounced on OI.

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Yilmaz, Hulya y Mustafa Culha. "A Drug Stability Study Using Surface-Enhanced Raman Scattering on Silver Nanoparticles". Applied Sciences 12, n.º 4 (10 de febrero de 2022): 1807. http://dx.doi.org/10.3390/app12041807.

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Pharmaceutical product quality is of vital importance for patient safety. Impurities and potential degradation products can cause changes in chemistry, pharmacological and toxicological properties by having a significant impact on product quality and safety. Stress-testing (forced degradation) studies of pharmaceutical preparations became necessary to assure degradation mechanisms and potential degradation products. Consequently, it is crucial to understand the nature of possible degradation products. Surface-enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopic technique that can provide valuable information about changes in a molecular structure with its intrinsic finger-print property. In this study, a forced degradation study was conducted on pemetrexed (PMT), an antifolate chemotherapy drug, in order to identify its likely chemical degradation products. The degradation mechanism of PMT was investigated under various experimental conditions; basic (0.1 M NaOH), acidic (0.1 M HCl), and oxidative (3% H2O2v/v). We used silver nanoparticles (AgNPs) of average size 60 nm as SERS substrates. The study shows that SERS can be a fast and reliable technique to study the stability and possible degradation mechanisms of drugs under several different conditions.

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Salmon, Olivia E., Lisa R. Welp, Michael E. Baldwin, Kristian D. Hajny, Brian H. Stirm y Paul B. Shepson. "Vertical profile observations of water vapor deuterium excess in the lower troposphere". Atmospheric Chemistry and Physics 19, n.º 17 (12 de septiembre de 2019): 11525–43. http://dx.doi.org/10.5194/acp-19-11525-2019.

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Abstract. We use airborne measurements of water vapor (H2Ov) stable isotopologues and complementary meteorological observations to examine how boundary layer (BL) dynamics, cloud processing, and atmospheric mixing influence the vertical structure of δD, δ18O, and deuterium excess (d excess =δD–8×δ18O) in the BL, inversion layer (INV), and lower free troposphere (FT). Flights were conducted around two continental US cities in February–March 2016 and included vertical profiles extending from near the surface to ≤2 km. We examine observations from three unique case study flights in detail. One case study shows observations that are consistent with Rayleigh isotopic distillation theory coinciding with clear skies, dry adiabatic lapse rates within the boundary layer, and relatively constant vertical profiles of wind speed and wind direction. This suggests that the air mass retained the isotopic fingerprint of dehydration during moist adiabatic processes upwind of the study area. Also, observed d-excess values in the free troposphere were sometimes larger than Rayleigh theory predicts, which may indicate mixing of extremely dehydrated air from higher altitudes. The two remaining case studies show isotopic anomalies in the d-excess signature relative to Rayleigh theory and indicate cloud processes and complex boundary layer development. The most notable case study with stratocumulus clouds present had extremely low (negative) d-excess values at the interface of the inversion layer and the free troposphere, which is possibly indicative of cloud or rain droplet evaporation. We discuss how in situ H2Ov stable isotope measurements, and d excess in particular, could be useful for improving our understanding of water phase changes, transport, and mixing that occurs between the BL, INV, and FT.

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Grdenić, D., M. Sikirica y D. Matković-Čalogović. "Trimercurated acetic acid. The crystal structures of [Hg(H2OHg)(NO3Hg)CCOO]NO3 and 2(NO3Hg)3CCOOH·HNO3". Journal of Organometallic Chemistry 306, n.º 1 (mayo de 1986): 1–7. http://dx.doi.org/10.1016/s0022-328x(00)98927-7.

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Yan, Qiuhui, Hong Zhang, Bingjie Sun y Liejin Guo. "Effect of Heating Method on Hydrogen Production by Biomass Gasification in Supercritical Water". Advances in Condensed Matter Physics 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/519389.

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The glucose as a test sample of biomass is gasified in supercritical water with different heating methods driven by renewable solar energy. The performance comparisons of hydrogen production of glucose gasification are investigated. The relations between temperature raising speed of reactant fluid, variation of volume fraction, combustion enthalpy, and chemical exergy of H2of the product gases with reactant solution concentration are presented, respectively. The results show that the energy quality of product gases with preheating process is higher than that with no preheating unit for hydrogen production. Hydrogen production quantity and gasification rate of glucose decrease obviously with the increase of concentration of material in no preheating system.

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Sharkas, Kamal, Kamal Wagle, Biswajit Santra, Sharmin Akter, Rajendra R. Zope, Tunna Baruah, Koblar A. Jackson, John P. Perdew y Juan E. Peralta. "Self-interaction error overbinds water clusters but cancels in structural energy differences". Proceedings of the National Academy of Sciences 117, n.º 21 (11 de mayo de 2020): 11283–88. http://dx.doi.org/10.1073/pnas.1921258117.

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We gauge the importance of self-interaction errors in density functional approximations (DFAs) for the case of water clusters. To this end, we used the Fermi–Löwdin orbital self-interaction correction method (FLOSIC) to calculate the binding energy of clusters of up to eight water molecules. Three representative DFAs of the local, generalized gradient, and metageneralized gradient families [i.e., local density approximation (LDA), Perdew–Burke–Ernzerhof (PBE), and strongly constrained and appropriately normed (SCAN)] were used. We find that the overbinding of the water clusters in these approximations is not a density-driven error. We show that, while removing self-interaction error does not alter the energetic ordering of the different water isomers with respect to the uncorrected DFAs, the resulting binding energies are corrected toward accurate reference values from higher-level calculations. In particular, self-interaction–corrected SCAN not only retains the correct energetic ordering for water hexamers but also reduces the mean error in the hexamer binding energies to less than 14 meV/H2Ofrom about 42 meV/H2Ofor SCAN. By decomposing the total binding energy into many-body components, we find that large errors in the two-body interaction in SCAN are significantly reduced by self-interaction corrections. Higher-order many-body errors are small in both SCAN and self-interaction–corrected SCAN. These results indicate that orbital-by-orbital removal of self-interaction combined with a proper DFA can lead to improved descriptions of water complexes.

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Rayment, M. B. y P. G. Jarvis. "Seasonal gas exchange of black spruce using an automatic branch bag system". Canadian Journal of Forest Research 29, n.º 10 (1 de octubre de 1999): 1528–38. http://dx.doi.org/10.1139/x99-130.

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Four large cuvettes were used to measure whole-branch CO2 and H2O vapour exchange at the Boreal Ecosystem-Atmosphere Study, Southern Study Area, Old Black Spruce site. Measurements started before the spring thaw and continued until after the winter freeze-up. Daytime photosynthesis, nighttime respiration, transpiration rate, and branch conductances were zero at the start and the end of the measurement period. Maximum photosynthetic uptake rates were ca. 6 µmol·m-2·s-1 (0.02 µmol·g-1·s-1). Maximum nighttime respiration was ca. 0.8 µmol·g-1·s-1. Maximum transpiration rates were ca. 2 mmol·m-2·s-1 (7.1 µmol·g-1·s-1). Maximum branch conductance was ca. 35 mmol·m-2·s-1 (0.123 mmol·g-1·s-1). A simple model combining light and temperature responses accounted for 80-90% of the day-to-day variation in daytime carbon uptake. Total annual daytime carbon uptake ranged from 151 to 271 g·m-2 (530-868 mg·g-1). Total nighttime loss ranged from 12.7 to 15.5 g C·m-2 (22.4-27.3 mg C·g-1). Total transpiration ranged from 20.4 to 35.0 kg H2O·m-2 (70.2-112.2 g H2O·g-1).

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Bazin, D., P. Parent, C. Laffon, O. Ducreux, J. Lynch, I. Kovacs, L. Guczi y F. De Groot. "Following the reduction under H2of supported cobalt catalysts through theLabsorption edges". Journal of Synchrotron Radiation 6, n.º 3 (1 de mayo de 1999): 430–32. http://dx.doi.org/10.1107/s0909049599000072.

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Minkwitz, Rolf y Gabriele Nowicki. "Die Monofluoroxonium(0)-hexafluorometallate(VI) H2OF⊕MF⊖6 (M  As, Sb)". Angewandte Chemie 102, n.º 6 (junio de 1990): 692–93. http://dx.doi.org/10.1002/ange.19901020620.

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Minkwitz, Rolf y Gabriele Nowicki. "The Monofluorooxonium(0) Hexafluorometalate(VI)S H2OF⊕MF6⊕(M= As,Sb)". Angewandte Chemie International Edition in English 29, n.º 6 (junio de 1990): 688–89. http://dx.doi.org/10.1002/anie.199006881.

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Dussert, Stéphane, Nathalie Chabrillange, Florent Engelmann y Serge Hamon. "Quantitative estimation of seed desiccation sensitivity using a quantal response model: application to nine species of the genus Coffea L." Seed Science Research 9, n.º 2 (febrero de 1999): 135–44. http://dx.doi.org/10.1017/s096025859900015x.

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AbstractSeed desiccation sensitivity was studied in nine species of the genus Coffeaby measuring seed viability after equilibration over various saturated salt solutions. A quantal response model based on the logistic distribution was developed in order to describe the typical S-shaped patterns observed. The closeness of fit of the desiccation sensitivity model was shown, and the assumption that seed desiccation sensitivity follows a continuous distribution within species was verified. For each species, the water content at which 50% of initial viability was reached, WC50, and a specific parameter describing the intra-specific variability, β, were calculated using a non-linear regression. A simplified water sorption model was developed which allowed easy calculation of water activity and water potential corresponding to WC50 (aw50 and Ψ50) for relative humidities ranging between 10 and 100%. Distribution of WC50and Ψ50 (or aw50) in the genus Coffea was homogeneous within the following intervals: from 0.05 to 0.38 g H2O.g−1dw for WC50 and from −168 to −11 MPa for Ψ50. Different classifications of the coffee species studied as regards to their desiccation sensitivity were obtained depending on whether WC50 or Ψ50was used for classification. The continuum for desiccation sensitivity observed within the nine species studied confirmed that coffee is an appropriate material for studying desiccation sensitivity.

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Matkowski, Patryk, Aleksander Lisowski y Adam Świętochowski. "Characterisation of Wheat Straw Pellets Individually and in Combination with Cassava Starch or Calcium Carbonate under Various Compaction Conditions: Determination of Pellet Strength and Water Absorption Capacity". Materials 13, n.º 19 (1 de octubre de 2020): 4375. http://dx.doi.org/10.3390/ma13194375.

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This study aimed to optimise the production conditions of wheat straw (WS) pellets and pellets with the additives of cassava starch (CS) or calcium carbonate (CC) based on the criteria of pellet strength and water absorption by crushed pellets. The pellets produced using a 2–10%-wt/wt additive ratio, material moisture of 10–30% w.b., die height of 66–86 mm, and material temperature of 78–108 °C were tested. The influence these factors on the strength parameters of pellets was different than on the water absorption by the crushed pellets. The pellets made of WS blended with CC additive were characterised by better strength parameters and the compressed pellets were characterised by better water absorption than those with CS. High and positive correlation among specific pellet compression work, elasticity modulus for pellet compression, and tensile strength values were observed. As the strength parameters of pellets showed high correlation with single pellet density, for the consistency of conclusions, the optimal conditions for pellet production were assumed based on the density. For optimal conditions at 4% wt/wt additive ratio, 23% w.b. material moisture, 78 mm die height, and 80 °C material temperature, the specific pellet compression work was 3.22 mJ·mm−2, elasticity modulus was 5.78 MPa, and maximum tensile strength of the pellets was 2.68 MPa; moreover, the water absorption by crushed pellets amounted to 2.60 g H2O·g−1 of dry matter.

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Zamorano, Ana, Nuria Rendón, José E. V. Valpuesta, Eleuterio Álvarez y Ernesto Carmona. "Synthesis and Reactivity toward H2of (η5-C5Me5)Rh(III) Complexes with Bulky Aminopyridinate Ligands". Inorganic Chemistry 54, n.º 13 (11 de junio de 2015): 6573–81. http://dx.doi.org/10.1021/acs.inorgchem.5b00905.

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BALDUYCK, Malika, Frank PIVA, Charlotte MIZON, Pierrette MAES, Nouzah MALKI, Bernard GRESSIER, Catherine MICHALSKI y Jacques MIZON. "Human Leucocyte Elastase (HLE) Preferentially Cleaves the Heavy Chain H2of Inter-α-Trypsin Inhibitor (ITI)". Biological Chemistry Hoppe-Seyler 374, n.º 7-12 (enero de 1993): 895–902. http://dx.doi.org/10.1515/bchm3.1993.374.7-12.895.

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Schäfer, Caspar, Bärbel Friedrich y Oliver Lenz. "Novel, Oxygen-Insensitive Group 5 [NiFe]-Hydrogenase in Ralstonia eutropha". Applied and Environmental Microbiology 79, n.º 17 (21 de junio de 2013): 5137–45. http://dx.doi.org/10.1128/aem.01576-13.

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ABSTRACTRecently, a novel group of [NiFe]-hydrogenases has been defined that appear to have a great impact in the global hydrogen cycle. This so-called group 5 [NiFe]-hydrogenase is widespread in soil-living actinobacteria and can oxidize molecular hydrogen at atmospheric levels, which suggests a high affinity of the enzyme toward H2. Here, we provide a biochemical characterization of a group 5 hydrogenase from the betaproteobacteriumRalstonia eutrophaH16. The hydrogenase was designated an actinobacterial hydrogenase (AH) and is catalytically active, as shown by thein vivoH2uptake and by activity staining in native gels. However, the enzyme does not sustain autotrophic growth on H2. The AH was purified to homogeneity by affinity chromatography and consists of two subunits with molecular masses of 65 and 37 kDa. Among the electron acceptors tested, nitroblue tetrazolium chloride was reduced by the AH at highest rates. At 30°C and pH 8, the specific activity of the enzyme was 0.3 μmol of H2per min and mg of protein. However, an unexpectedly high Michaelis constant (Km) for H2of 3.6 ± 0.5 μM was determined, which is in contrast to the previously proposed lowKmof group 5 hydrogenases and makes atmospheric H2uptake byR. eutrophamost unlikely. Amperometric activity measurements revealed that the AH maintains full H2oxidation activity even at atmospheric oxygen concentrations, showing that the enzyme is insensitive toward O2.

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Viana, Willian Goudinho, Ana Paula Lando, Rosa Angelica da Silva, Cláudia Dias da Costa, Pedro Henrique Mastriane Vieira y Neusa Steiner. "Physiological performance of Garcinia gardneriana (Planch. & Triana) Zappi: a species with recalcitrant and dormant seeds". Journal of Seed Science 42 (2020). http://dx.doi.org/10.1590/2317-1545v42222357.

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Abstract: Garcinia gardneriana (Planch. & Triana) Zappi is a native species widely distributed in Brazil. It has ornamental features, edible fruits, and its leaves have medicinal properties; however, its potential has not been explored. The aim of this study was to evaluate seed physiological performance due to dormancy, desiccation and storage tolerance. Only decoated seeds germinated. Seeds had an initial water content of 1.07 g H2O.g-1 dw and final germination of 95%. Both desiccation to 0.67 g H2O.g-1 dw and storage at 25 ºC for ninety days resulted in decreased germination, 43 and 41%, respectively. Desiccation below 0.25 g H2O.g-1 dw and storage for ninety days at 5 ºC were lethal. A rapid decrease in enzymic protection by superoxide dismutase and ascorbate peroxidase was correlated to desiccation sensitivity. Total polyamines content was higher in fresh seeds and markedly decreased with desiccation. The decrease in enzyme activity and polyamines content seems to be associated with seed viability loss. In sum, G. gardneriana seeds have a low tolerance to desiccation and are sensitive to chilling. Therefore, the seeds can be categorized as recalcitrant and dormant, a rare combination in terms of seed biology.

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MINKWITZ, R. y G. NOWICKI. "ChemInform Abstract: The Monofluorooxonium(0)-hexafluorometalates(VI) H2OF+MF- 6 (M: As, Sb)." ChemInform 21, n.º 35 (28 de agosto de 1990). http://dx.doi.org/10.1002/chin.199035031.

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BRACA, G., A. M. RASPOLLI GALLETTI, G. SBRANA y R. LAZZARONI. "ChemInform Abstract: Homologation with CO + H2of Ethyl Orthoformate in the Presence of Ruthenium Catalysts: A Stepwise Hydrogenation and Carbonylation Reaction." Chemischer Informationsdienst 17, n.º 2 (14 de enero de 1986). http://dx.doi.org/10.1002/chin.198602142.

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Artículos de revistas sobre el tema "H2OFVG"

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