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11.
Ali Diyapoglu Tao-Ho Chang Pi-Fang Linda Chang Jyh-Herng Yen Hsin-I Chiang Menghsiao Meng 《Molecules (Basel, Switzerland)》2022,27(15)
Plant-parasitic nematodes infect a diversity of crops, resulting in severe economic losses in agriculture. Microbial volatile organic compounds (VOCs) are potential agents to control plant-parasitic nematodes and other pests. In this study, VOCs emitted by a dozen bacterial strains were analyzed using solid-phase microextraction followed by gas chromatography–mass spectrometry. Fumigant toxicity of selected VOCs, including dimethyl disulfide (DMDS), 2-butanone, 2-pentanone, 2-nonanone, 2-undecanone, anisole, 2,5-dimethylfuran, glyoxylic acid, and S-methyl thioacetate (MTA) was then tested against Caenorhabditis elegans. DMDS and MTA exhibited much stronger fumigant toxicity than the others. Probit analysis suggested that the values of LC50 were 8.57 and 1.43 μg/cm3 air for DMDS and MTA, respectively. MTA also showed stronger fumigant toxicity than DMDS against the root-knot nematode Meloidogyne incognita, suggesting the application potential of MTA. 相似文献
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Jeanice B. Thomas James H. Yen Katherine E. Sharpless 《Analytical and bioanalytical chemistry》2013,405(13):4539-4548
The vitamin C concentrations in three food-matrix Standard Reference Materials (SRMs) from the National Institute of Standards and Technology (NIST) have been determined by liquid chromatography (LC) with absorbance detection. These materials (SRM 1549a Whole Milk Powder, SRM 1849a Infant/Adult Nutritional Formula, and SRM 3233 Fortified Breakfast Cereal) have been characterized to support analytical measurements made by food processors that are required to provide information about their products’ vitamin C content on the labels of products distributed in the United States. The SRMs are primarily intended for use in validating analytical methods for the determination of selected vitamins, elements, fatty acids, and other nutrients in these materials and in similar matrixes. They can also be used for quality assurance in the characterization of test samples or in-house control materials, and for establishing measurement traceability. Within-day precision of the LC method used to measure vitamin C in the food-matrix SRMs characterized in this study ranged from 2.7 % to 6.5 %. 相似文献
15.
Synthesis of RGO/Cu8S5/PPy Composite Nanosheets with Enhanced Peroxidase‐Like Activity for Sensitive Colorimetric Detection of H2O2 and Phenol 下载免费PDF全文
Yanzhou Jiang Yan Gu Guangdi Nie Maoqiang Chi Zezhou Yang Ce Wang Yen Wei Xiaofeng Lu 《Particle & Particle Systems Characterization》2017,34(3)
In this paper, a novel strategy for the fabrication of reduced graphene oxide (rGO)/Cu8S5/polypyrrole (PPy) composite nanosheets with Cu8S5 nanoparticles and PPy layer anchored on the surface of rGO as peroxidase‐like nanocatalyst is reported. During the synthesis, graphene oxide (GO)/CuO composite nanosheets are prepared first and used as templates, then the sulfuration of CuO and polymerization of pyrrole are accompanied with the reduction of GO, resulting in ternary rGO/Cu8S5/PPy composite nanosheets. The synthesized Cu8S5 nanoparticles with a diameter in the range from tens to hundreds of nanometers are dispersed within PPy decorated rGO nanosheets. The resultant ternary rGO/Cu8S5/PPy composite nanosheets exhibit a higher peroxidase‐like catalytic activity toward the oxidation of 3,3′,5,5′‐tetramethylbenzidine in the presence of H2O2 than GO/CuO and rGO/CuS composite nanosheets, revealing a synergistic effect on their activity. The as‐prepared rGO/Cu8S5/PPy platform provides a simple colorimetric approach for the detection of H2O2 and phenol with a high sensitivity. This work offers a new way for the fabrication of rGO‐based nanocomposite with superior enzyme‐like activity, which displays great potential applications in biocatalysis and environmental monitoring. 相似文献
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Let (P) denote the vector maximization problem
where the objective functions f
i
are strictly quasiconcave and continuous on the feasible domain D, which is a closed and convex subset of R
n
. We prove that if the efficient solution set E(P) of (P) is closed, disconnected, and it has finitely many (connected) components, then all the components are unbounded. A similar fact is also valid for the weakly efficient solution set E
w
(P) of (P). Especially, if f
i
(i=1,...,m) are linear fractional functions and D is a polyhedral convex set, then each component of E
w
(P) must be unbounded whenever E
w
(P) is disconnected. From the results and a result of Choo and Atkins [J. Optim. Theory Appl. 36, 203–220 (1982.)] it follows that the number of components in the efficient solution set of a bicriteria linear fractional vector optimization problem cannot exceed the number of unbounded pseudo-faces of D. 相似文献
19.
Transparent conductive ZnO:Ga thin films were deposited on Corning 1737 glass substrate by pulsed direct current (DC) magnetron sputtering. The effects of process parameters, namely pulse frequency and film thickness on the structural and optoelectronic properties of ZnO:Ga thin films are evaluated. It shows that highly c-axis (0 0 2) oriented polycrystalline films with good visible transparency and electrical conductivity were prepared at a pulsed frequency of 10 kHz. Increasing the film thickness also enlarged the grain size and carrier mobility which will subsequently lead to the decrease in resistivity. In summary, ZnO:Ga thin film with the lowest electrical resistivity of 2.01 × 10−4 Ω cm was obtained at a pulse frequency of 10 kHz with 500 nm in thickness. The surface RMS (root mean square) roughness of the film is 2.9 nm with visible transmittance around 86% and optical band gap of 3.83 eV. 相似文献
20.
A model is developed for the formation and propagation of cracks in a material sample that is heated at its top surface, pyrolyses, and then thermally degrades to form char. In this work the sample is heated uniformly over its entire top surface by a hypothetical flame (a heat source). The pyrolysis mechanism is described by a one-step overall reaction that is dependent nonlinearly on the temperature (Arrhenius form). Stresses develop in response to the thermal degradation of the material by means of a shrinkage strain caused by local mass loss during pyrolysis. When the principal stress exceeds a prescribed threshold value, the material forms a local crack. Cracks are found to generally originate at the surface in response to heating, but occasionally they form in the bulk, away from ever-changing material boundaries. The resulting cracks evolve and form patterns whose characteristics are described. Quantities examined in detail are: the crack spacing in the pyrolysis zone; the crack length evolution; the formation and nature of crack loops which are defined as individual cracks that have joined to form loops that are disconnected from the remaining material; the formation of enhanced pyrolysis area; and the impact of all of the former quantities on mass flux. It is determined that the mass flux from the sample can be greatly enhanced over its nominal (non-cracking) counterpart. The mass efflux profile qualitatively resembles those observed in Cone Calorimeter tests. 相似文献