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51.
J. Loureiro J. Amorim 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(3):421-429
The three- and one-dimensional velocity distributions of a product species created by an exothermic reaction are calculated
using the energy conservation, with the aim of evaluating the impact of such processes on the anomalous broadening of Doppler
lines. The calculations are performed to the reaction H2+ + H2 → H3+ + H, in which according to Christoffersen (1964) an amount of 1.56 eV is transferred to the product species. It is shown
that the deviations relatively to Maxwell-Boltzmann distributions are significant as the internal energy defect ΔE increases, even within energies lower than 1.56 eV, and hence the profiles of excited H∗ atoms, associated with the emission of hydrogen Balmer lines, created in the sequence of H(n = 1) produced by the above reaction are not of Gaussian-type. The profiles are markedly flatter and squarer than Gaussian
distributions. The validity of the species temperature determined from the full width at half maximum (FWHM) of the lines,
as well as the fit of the lines by multimodal Gaussian functions, is then analyzed. 相似文献
52.
53.
Laila D. Kazimierski Guillermo Abramson Marcelo N. Kuperman 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(10):232
We study a simple model of a foraging animal that modifies the substrate on which itmoves. This substrate provides its only resource, and the forager manages it by taking alimited portion at each visited site. The resource recovers its value after the visitfollowing a relaxation law. We study different scenarios to analyze the efficiency of themanaging strategy, corresponding to control the bite size. We observe the non trivialemergence of a home range, that is visited in a periodic way. The duration of thecorresponding cycles and the transient until it emerges is affected by the bite size. Ourresults show that the most efficient use of the resource, measured as the balance betweengathering and traveled distance, corresponds to foragers that take larger portions butwithout exhausting the resource. We also analyze the use of space determining the numberof attractors of the dynamics, and we observe that it depends on the bite size and therecovery time of the resource. 相似文献
54.
Alejandro J. González Fá Isabella Cerutti Valeria Springer Stefano Girotti María E. Centurión María S. Di Nezio Marcelo F. Pistonesi 《Chromatographia》2017,80(9):1459-1466
The development of methodologies for the characterization of silver nanoparticles (AgNPs) synthesized using natural products has received increasing attention, especially to monitoring its stability and size for further application. In this paper, a capillary electrophoretic (CE) method is presented for characterization of AgNPs synthesized using honey or glucose as reducing agents. A simple electrolyte solution composed of 20 mM sodium borate and 20 mM sodium dodecylsulfate (SDS) at pH 8.5 was used for separation of AgNPs within a short analysis time (<12 min). The obtained results were compared with the traditional characterization techniques, such as transmission electron microscopy (TEM) and dynamic light scattering (DLS), showing satisfactory correlation in terms of size distribution. In addition, valuable information about electrophoretic mobility and zeta potential values of AgNPs was obtained by applying the CE-UV/Vis method. Thus, the proposed methodology represents a straightforward tool for the fast and cost-effective characterization of AgNPs within a single analysis, employing minimal amounts of reagents and samples. 相似文献
55.
Barbara Bojko Krzysztof Gorynski German Augusto Gomez-Rios Jan Matthias Knaak Tiago Machuca Vinzent Nikolaus Spetzler Erasmus Cudjoe Michael Hsin Marcelo Cypel Markus Selzner Mingyao Liu Shaf Keshavjee Janusz Pawliszyn 《Analytica chimica acta》2013
Metabolomics and biomarkers discovery are an integral part of bioanalysis. However, untargeted tissue analysis remains as the bottleneck of such studies due to the invasiveness of sample collection, as well as the laborious and time-consuming sample preparation protocols. In the current study, technology integrating in vivo sampling, sample preparation and global extraction of metabolites – solid phase microextraction was presented and evaluated during liver and lung transplantation in pig model. Sampling approaches, including selection of the probe, transportation, storage conditions and analyte coverage were discussed. The applicability of the method for metabolomics studies was demonstrated during lung transplantation experiments. 相似文献
56.
Regioselective synthesis of haloaromatic tertiary alcohols can be achieved by ortho deprotonation/electrophilic reactions of (η6- fluoroarene)Cr(CO)3 complexes with halobenzophenones and metal removal. The coexistence of different halogens in the aromatic rings of these molecules make them unique within the group of tertiary alcohols. 相似文献
57.
Kobelnik Marcelo Valentin Leonardo Antônio Valentin Clever Aparecido Lavoie Fernando Luiz da Silva Jefferson Lins Ribeiro Clóvis Augusto 《Journal of Thermal Analysis and Calorimetry》2022,147(21):11739-11745
Journal of Thermal Analysis and Calorimetry - Asphalt emulsion is a versatile product that can be used for different waterproofing applications in civil construction and highway constructions.... 相似文献
58.
Alejandra Medrano-Banda Dr. Alfonso Crespo-Yapur Dr. Miguel Ángel Velasco-Soto Dr. Marcelo Videa 《ChemistryOpen》2022,11(2):e202100241
The synthesis of hybrid platinum materials is fundamental to enable alkaline water electrolysis for cost-effective H2 generation. In this work, we have used a galvanostatic method to co-deposit PtNi films onto polycrystalline gold. The surface concentrations of Ni (ΓNi) and Pt (ΓPt) were calculated from electrochemical measurements; the ΓPt/ΓNi ratio and electrocatalytic activity of these materials towards hydrogen evolution reaction (HER) in 1 M KOH show a strong dependence on the current density pulse applied during the electrodeposition. Analysis of the Tafel parameters hints that, on these deposits, HER proceeds through a Volmer-Heyrovsky mechanism. The galvanostatically deposited PtNi layers present a high current output per Pt gram, 3199 A gPt−1, which is significantly larger compared to other PtNi-based materials obtained by more extended and more complex synthesis methods. 相似文献
59.
The most challenging task of creating a bioengineered ovary to restore fertility in cancer patients is choosing an appropriate biomaterial to encapsulate isolated preantral follicles and ovarian cells. In this study, as a biocompatible and biodegradable biomaterial containing fibrin-like bioactivity and manageable physical properties, PEGylated fibrin aims to encapsulate isolated ovarian stromal cells as a first step of creating an engineered ovarian tissue. For this purpose, human ovarian stromal cells were isolated from frozen-thawed ovarian tissue and cultured in the PEGylated fibrin hydrogels (PEG:Fib), which were fabricated by combining two different molar ratios of PEG:Fib (10:1 and 5:1) and two thrombin concentrations. The samples were analyzed at days 0 and 5 of in vitro for cell density, proliferation (Ki67), and apoptosis (caspase-3). Moreover, LIVE/DEAD and PrestoBlue assays assessed cell viability and proliferation on days 1, 3, and 5. The effect of PEGylation on the biodegradation behavior of fibrin was evaluated by measuring the remaining mass ratio of non-modified fibrin, PEG:Fib 10:1, and PEG:Fib 5:1 hydrogels after 1, 2, 3, 5, 8, 11, and 15 days. The results showed that PEGylated fibrin hydrogels enhanced scaffold stability and supported cell viability and proliferation. In addition, PEG:Fib 5:1 T50 indicated a significantly higher cell density dynamic and non-significantly lower expression of caspase-3 on day 5. Besides, uniformity of cell distribution inside the hydrogel and a tendency to a high rate of Ki67-positive cells was observed in PEG:Fib 10:1 T50 hydrogels. In conclusion, this study reveals the positive effects of PEGylated fibrin hydrogels on isolated human ovarian stromal cells. Based on such promising findings, we believe that this matrix should be tested to encapsulate isolated human ovarian follicles. 相似文献
60.
Felix Duensing Elisabeth Gruber Paul Martini Marcelo Goulart Michael Gatchell Bilal Rasul Olof Echt Fabio Zappa Masoomeh Mahmoodi-Darian Paul Scheier 《Molecules (Basel, Switzerland)》2021,26(12)
Complexes of atomic gold with a variety of ligands have been formed by passing helium nanodroplets (HNDs) through two pickup cells containing gold vapor and the vapor of another dopant, namely a rare gas, a diatomic molecule (H2, N2, O2, I2, P2), or various polyatomic molecules (H2O, CO2, SF6, C6H6, adamantane, imidazole, dicyclopentadiene, and fullerene). The doped HNDs were irradiated by electrons; ensuing cations were identified in a high-resolution mass spectrometer. Anions were detected for benzene, dicyclopentadiene, and fullerene. For most ligands L, the abundance distribution of AuLn+ versus size n displays a remarkable enhancement at n = 2. The propensity towards bis-ligand formation is attributed to the formation of covalent bonds in Au+L2 which adopt a dumbbell structure, L-Au+-L, as previously found for L = Xe and C60. Another interesting observation is the effect of gold on the degree of ionization-induced intramolecular fragmentation. For most systems gold enhances the fragmentation, i.e., intramolecular fragmentation in AuLn+ is larger than in pure Ln+. Hydrogen, on the other hand, behaves differently, as intramolecular fragmentation in Au(H2)n+ is weaker than in pure (H2)n+ by an order of magnitude. 相似文献