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991.
Atomistic simulations, using the second-generation reactive empirical bond order (REBO) potential, are performed to investigate the uniaxial tensile behaviors of single-walled carbon nanotubes (SWCNTs). It is found that the effect of the nanotube diameters on the elastic modulus, the tensile strength and the stress vs. strain relation of SWCNTs is small yet noticeable. However, the effect of the degree of helicity is significant. 相似文献
992.
Philippe Ungerer Aurélie Wender Grégoire Demoulin Émeric Bourasseau Pascal Mougin 《Molecular simulation》2013,39(10):631-648
The design of improved processes for producing hydrogen sulphide (H2S)-rich natural gases faces a general scarcity of experimental data, because of the high toxicity and corrosive character of H2S. We present here a prospective application of Monte Carlo simulation to predict desired fluid properties. A first step was the selection of intermolecular potentials for water, H2S, carbon dioxide (CO2) and methane on the basis of pure component properties (vapour pressures, vapourisation enthalpies, liquid densities, supercritical densities at high pressure). A second step involved the prediction of phase diagrams of binary and ternary mixtures of the methane–H2S–water system, using two-phase and three-phase Gibbs ensemble simulations. In a third step the density and excess enthalpy of the CO2–H2S system were computed for a large range of pressure, temperature and compositions. Comparison with available experimental data showed that all investigated properties could be consistently predicted without needing parameter calibration on binary data. The results also provided a qualitative understanding of water solubility in H2S-rich fluids based on molecular self-association. 相似文献
993.
Hong Pyo Kim Hyun-Ock Pae Sung Hun Back Su Wol Chung Je Moon Woo Yong Son Hun-Taeg Chung 《Biochemical and biophysical research communications》2011,404(1):569
Originally identified as a rate-limiting enzyme for heme catabolism, heme oxygenase-1 (HO-1) has expanded its roles in anti-inflammation, anti-apoptosis and anti-proliferation for the last decade. Regulation of protein activity by location is well appreciated. Even though multiple compartmentalization of HO-1 has been documented, the functional implication of this enzyme at these subcellular organelles is only partially elucidated. In this review we discuss the endoplasmic reticulum (ER)-residing HO-1 and its cytoprotective activity against ER stress. 相似文献
994.
A new amperometric immunosensor for the determination of carcinoembryonic antigen (CEA) was constructed. First, the uniform nanomultilayer film was fabricated via layer-by-layer (LBL) assembly of positively charged carbon nanotubes wrapped by poly(diallyldimethylammonium chloride) and negatively charged poly(sodium-p-styrene-sulfonate), which could provide a high accessible surface area and a biocompatible microenvironment. Subsequently, gold nanoclusters were electrodeposited on the electrode to immobilize anti-CEA. The fabricated process and electrochemical behaviors of the immunosensor were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Under optimal conditions, the proposed immunosensor could detect CEA in two linear ranges from 0.1 to 2.0 ng mL−1 and from 2.0 to 160.0 ng mL−1, with a detection limit of 0.06 ng mL−1. 相似文献
995.
Membrane inlet mass spectrometry (MIMS) uses diffusion across a permeable membrane to detect in solution uncharged molecules of small molecular weight. We point out here the application of MIMS to determine catalytic properties of decarboxylases using as an example catalysis by oxalate decarboxylase (OxDC) from Bacillus subtilis. The decarboxylase activity generates carbon dioxide and formate from the nonoxidative reaction but is accompanied by a concomitant oxidase activity that consumes oxalate and oxygen and generates CO2 and hydrogen peroxide. The application of MIMS in measuring catalysis by OxDC involves the real-time and continuous detection of oxygen and product CO2 from the ion currents of their respective mass peaks. Steady-state catalytic constants for the decarboxylase activity obtained by measuring product CO2 using MIMS are comparable to those acquired by the traditional endpoint assay based on the coupled reaction with formate dehydrogenase, and measuring consumption of O2 using MIMS also estimates the oxidase activity. The use of isotope-labeled substrate (13C2-enriched oxalate) in MIMS provides a method to characterize the catalytic reaction in cell suspensions by detecting the mass peak for product 13CO2 (m/z 45), avoiding inaccuracies due to endogenous 12CO2. 相似文献
996.
A new electrochemical immunoassay of alpha-fetoprotein (AFP) was developed on an organic–inorganic hybrid nanostructure-functionalized carbon electrode by coupling with magnetic bionanolabels. Multi-walled carbon nanotubes (CNTs), single-stranded DNA, thionine and AFP were utilized for the construction of the immunosensor, while the core–shell Fe3O4-silver nanocomposites were employed for the label of horseradish peroxidase-anti-AFP conjugates (HRP-anti-AFP-AgFe). Electrochemical measurement toward AFP was carried out by using magnetic bionanolabels as traces and H2O2 as enzyme substrate with a competitive-type immunoassay mode. Experimental results indicated that the immunosensors with carbon nanotubes and DNA exhibited better electrochemical responses than those of without carbon nanotubes or DNA. Under optimal conditions, the electrochemical immunosensor by using HRP-anti-AFP-AgFe as signal antibodies exhibited a linear range of 0.001–200 ng mL−1 AFP with a low detection limit of 0.5 pg mL−1 at 3sB. Both intra- and inter-assay coefficients of variation were 7.3%, 9.4%, 8.7% and 10.2%, 7.8%, 9.4% toward 0.01, 30, 120 ng mL−1 AFP, respectively. The specificity and stability of the electrochemical immunoassay were acceptable. In addition, the methodology was validated for 12 clinical serum specimens including 9 positive specimens and 3 normal specimens, receiving a good correlation with the results obtained from the referenced electrochemiluminescence assay. 相似文献
997.
Yu YP Li ZG Wang DZ Zhan X Shao JH 《Biochemical and biophysical research communications》2011,(1):6-9
Hydrogen sulfide (H2S) has been recognized as a toxic gas and environment pollutant. So, it is seldom regarded as a therapeutic gas. H2S has been recognized recently as a novel gaseous messenger and serves as an important neuromodulator in the central nervous system. Many researches have been focused on the protective role of H2S in treatment of several diseases. Like nitric oxide (NO) and carbon monoxide (CO), which are considered as two gaseous transmitters, H2S has been regarded as the third one. Recent studies provided evidence that H2S exerted antioxidant and anti-apoptotic effects, which protected neurons, cardiomyocytes, pancreatic β-cells and vascular smooth muscle cells against oxidative stress by scavenging reactive oxygen species (ROS) and reactive nitrogen species (RNS). It has been known that multiple factors, including oxidative stress, free radicals and neuronal nitric oxide syntheses as well as abnormal inflammatory responses are involved in the mechanism underlying the brain injury after acute CO poisoning. Studies have shown that free radical scavengers can display neuroprotective properties. Therefore, we hypothesize that H2S might be an interesting potential strategy for curing acute CO poisoning. 相似文献
998.
Wenwen Liu Matthew Li Gaopeng Jiang Gaoran Li Jianbing Zhu Meiling Xiao Yanfei Zhu Rui Gao Aiping Yu Ming Feng Zhongwei Chen 《Liver Transplantation》2020,10(29)
Graphene quantum dots (GQDs) have aroused great interest in the scientific community in recent years due to their unique physicochemical properties and potential applications in different fields. To date, much research has been conducted on the ingenious design and rational construction of GQDs‐based nanomaterials used as electrode materials and/or electrocatalysts. Despite these efforts, research on the efficient synthesis and application of GQDs‐based nanomaterials is still in the early stages of development and timely updates of recent research progress on new design concepts, synthetic strategies, and significant breakthroughs in GQDs‐based nanomaterials are highly desired. In light of the above, the effect of synthetic methods on the final product of the GQDs, the GQDs synthesis mechanism, and specific perspectives regarding the effect of the unique surface and structural properties of GQDs (e.g., defects, heteroatom doping, surface/edge state, size, conductivity) on the electrochemical energy‐related systems are discussed in‐depth in this review. Additionally, this review also focuses on the design of GQDs‐based composites and their applications in the fields of electrochemical energy storage (e.g., supercapacitors and batteries) and electrocatalysis (e.g., fuel cell, water splitting, CO2 reduction), along with constructive suggestions for addressing the remaining challenges in the field. 相似文献
999.
Carolin Klose Torben Saatkamp Andreas Münchinger Luca Bohn Giorgi Titvinidze Matthias Breitwieser Klaus‐Dieter Kreuer Severin Vierrath 《Liver Transplantation》2020,10(14)
Hydrocarbon ionomers bear the potential to significantly lower the material cost and increase the efficiency of proton‐exchange membrane water electrolyzers (PEMWE). However, no fully hydrocarbon membrane electrode assembly (MEA) with a performance comparable to Nafion‐MEAs has been reported. PEMWE‐MEAs are presented comprising sPPS as membrane and electrode binder reaching 3.5 A cm?2 at 1.8 V and thus clearly outperforming state‐of‐the‐art Nafion‐MEAs (N115 as membrane, 1.5 A cm?2 at 1.8 V) due to a significantly lower high frequency resistance (57 ± 4 mΩ cm² vs 161 ± 7 mΩ cm²). Additionally, pure sPPS‐membranes show a three times lower gas crossover (<0.3 mA cm?2) than Nafion N115‐membranes (>1.1 mA cm?2) in a fully humidified surrogate test. Furthermore, more than 80 h of continuous operation is shown for sPPS‐MEAs in a preliminary durability test (constant current hold at 1 A cm?2 at 80 °C). These results rely on the unique transport properties of sulfonated poly(phenylene sulfone) (sPPS) that combines high proton conductivity with low gas crossover. 相似文献
1000.
Georg Frenck Leon van der Linden Teis Nørgaard Mikkelsen Hans Brix Rikke Bagger Jørgensen 《Ecology and evolution》2013,3(5):1163-1172
Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi‐generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full‐factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co‐occur. 相似文献