排序方式: 共有53条查询结果,搜索用时 15 毫秒
41.
S. J. Reddy E. Mauerhofer N. Porte J. Damodar H. O. Denschlag 《Journal of Radioanalytical and Nuclear Chemistry》1998,238(1-2):83-90
Levels of As, Ba, Br, Ca, Ce, Cl, Cr, Cs, Eu, Fe, Hg, I, K, La, Mg, Mn, Na, Ni, Rb, Sb, Sc, Sm, Sr, Th, Zn, and U have been
determined in ten leaves widely used in ayurvedic medicine by instrumental neutron activation analysis (INAA). The neutron
irradiations were performed with a 100 kW Triga nuclear reactor and the induced activity was counted with a gamma-ray spectrometer.
Based on elemental levels obtained the utility of these leaves in medicine are discussed. 相似文献
42.
Photocatalytic performance of yttrium-doped CNT-ZnO nanoflowers synthesized from hydrothermal method
S.K. Sharma R. Gupta G. Sharma K. Vemula A.R. Koirala N.K. Kaushik E.H. Choi D.Y. Kim L.P. Purohit B.P. Singh 《Materials Today Chemistry》2021
We synthesized yttrium-doped CNT-ZnO (CNT-YZO) nanoparticles (NPs) and nanoflowers (NFs) from the hydrothermal method at 130 °C. The effect of Y3+-concentrations in nanostructured CNT-YZO was determined in terms of the photocatalytic degradation of methylene blue (MB). Microstructural analysis showed the hexagonal cubic structure of ZnO regardless of Y-concentration or the addition of CNTs during the nucleation and growth. The specific surface area, total pore volume, and mean pore diameter of typical CNT-YZO NFs were observed to be 36.109 m2/g, 0.162 cm3/g, and 17.932 nm, respectively. The photocatalytic degradation performance of CNT-YZO NFs improved due to increase reactive sites of the catalyst and reduced recombination of photo-induced carriers. The surface-area normalized first-order decomposition rates (r/m2) of CNT-YZO NFs showed the highest photocatalytic degradation (99%). The CNT-YZO has produced a new kind of material for the photocatalytic degradation under the irradiation of visible light using a solar simulator. 相似文献
43.
Yoctoliter Thermometry for Single‐Molecule Investigations: A Generic Bead‐on‐a‐Tip Temperature‐Control Module
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Deepak Koirala Jibin Abraham Punnoose Prakash Shrestha Prof. Hanbin Mao 《Angewandte Chemie (International ed. in English)》2014,53(13):3470-3474
A new temperature‐jump (T‐jump) strategy avoids photo‐damage of individual molecules by focusing a low‐intensity laser on a black microparticle at the tip of a capillary. The black particle produces an efficient photothermal effect that enables a wide selection of lasers with powers in the milliwatt range to achieve a T‐jump of 65 °C within milliseconds. To measure the temperature in situ in single‐molecule experiments, the temperature‐dependent mechanical unfolding of a single DNA hairpin molecule was monitored by optical tweezers within a yoctoliter volume. Using this bead‐on‐a‐tip module and the robust single‐molecule thermometer, full thermodynamic landscapes for the unfolding of this DNA hairpin were retrieved. These approaches are likely to provide powerful tools for the microanalytical investigation of dynamic processes with a combination of T‐jump and single‐molecule techniques. 相似文献
44.
A Carbon Electrode Functionalized by a Tricopper Cluster Complex: Overcoming Overpotential and Production of Hydrogen Peroxide in the Oxygen Reduction Reaction
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Dr. Natarajan Thiyagarajan Dr. Damodar Janmanchi Dr. Yi‐Fang Tsai Wondemagegn Hailemichael Wanna Dr. Ravirala Ramu Prof. Dr. Sunney I. Chan Prof. Dr. Jyh‐Myng Zen Prof. Dr. Steve S.‐F. Yu 《Angewandte Chemie (International ed. in English)》2018,57(14):3612-3616
A study of the oxygen reduction reaction (ORR) on a screen printed carbon electrode surface mediated by the tricopper cluster complex Cu3(7‐N‐Etppz(CH2OH)) dispersed on electrochemically reduced carbon black, where 7‐N‐Etppz(CH2OH) is the ligand 3,3′‐(6‐(hydroxymethyl)‐1,4‐diazepane‐1,4‐diyl)bis(1‐(4‐ethyl piperazin‐1‐yl)propan‐2‐ol), is described. Onset oxygen reduction potentials of about 0.92 V and about 0.77 V are observed at pH 13 and pH 7 vs. the reversible hydrogen electrode, which are comparable to the best values reported for any synthetic copper complex. Based on half‐wave potentials (E1/2), the corresponding overpotentials are about 0.42 V and about 0.68 V, respectively. Kinetic studies indicate that the trinuclear copper catalyst can accomplish the 4 e? reduction of O2 efficiently and the ORR is accompanied by the production of only small amounts of H2O2. The involvement of the copper triad in the O2 activation process is also verified. 相似文献
45.
An efficient approach has been developed for the synthesis of naturally occurring prenylated chalcones viz. kanzonol C(1), stipulin(2), crotaorixin(3), medicagenin(4), licoagrochalcone A(5) and abyssinone D(6) along with the pyranochalcones paratocarpin C(7), anthyllisone(8) and 3-O-methylabyssinone A(9).The key step of the synthesis is a Claisen–Schmidt condensation. Subsequently, their anti-inflammatory effects were investigated in lipopolysaccharides(LPSs)-induced RAW-264.7 macrophages. Of the synthesized chalcones, compounds 5(IC_(50)= 10.41 μmol/L), 6(IC_(50)= 9.65 μmol/L) and 8(IC_(50)= 15.34 μmol/L) show remarkable activity with no cytotoxicity. Compound 9(IC_(50)= 4.5 μmol/L)exhibits maximum(83.6%) nitric oxide(NO) inhibition, but shows slight cytotoxicity. The results reveal that the chalcones bearing the prenyl group at 3- and/or 5-position on ring A(acetophenone moiety), i.e.,1–4 and 7 show weak, or no inhibition activity, whereas chalcones having the prenyl group only on ring B(aldehyde part), i.e., 5, 6 and 8 show significant activity on the production of inflammatory mediated NO with no cytotoxicity. 相似文献
46.
Biswanath Das Kongara Damodar Nikhil Chowdhury Darshanala Saritha Bommena Ravikanth Maddeboina Krishnaiah 《Tetrahedron》2008,64(40):9396-9400
α-Amido sulfones undergo aza-Morita-Baylis-Hillman reaction efficiently with alkyl acrylates under neat conditions in the presence of DABCO at room temperature. These sulfones generate aryl imines in the presence of DABCO and form the corresponding adducts in high yields (85-94%) within 9-12 h. 相似文献
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48.
Single nucleotide polymorphism (SNP) is the most common genetic variation among individuals. The association of SNP with individual's response to pathogens, phenotypic variations, and gene functions emphasizes the importance of sensitive and reliable SNP detection for biomedical diagnosis and therapy. To increase sensitivity, most approaches employ amplification steps, such as PCR, to generate detectable signals that are usually ensemble-averaged. Introduction of amplification steps increases the complexity of a system, whereas ensemble averaging of signals often suffers from background interference. Here, we have exploited the stochastic behavior of a single-molecule probe to recognize SNP sequence in a microfluidic platform using a laser-tweezers instrument. The detection relies on on-off mechanical signals that provide little background interference and high specificity between wild type and SNP sequences. The microfluidic setting allows multiplex sensing and in situ recycling of the SNP probe. As a proof-of-concept, we have detected as low as 100 pM of an SNP target associated with coronary heart diseases within half an hour without any amplification steps. The mechanical signal permits the detection of single mutations involving either G/C or A/T pairs. We anticipate this system has the capacity to function as a highly sensitive generic biosensor after incorporation of a specific recognition element, such as an aptamer for example. 相似文献
49.
Chuan Li Zhe Jia Arghya Chakravorty Swagata Pahari Yunhui Peng Sankar Basu Mahesh Koirala Shailesh Kumar Panday Marharyta Petukh Lin Li Emil Alexov 《Journal of computational chemistry》2019,40(28):2502-2508
Electrostatic potential, energies, and forces affect virtually any process in molecular biology, however, computing these quantities is a difficult task due to irregularly shaped macromolecules and the presence of water. Here, we report a new edition of the popular software package DelPhi along with describing its functionalities. The new DelPhi is a C++ object-oriented package supporting various levels of multiprocessing and memory distribution. It is demonstrated that multiprocessing results in significant improvement of computational time. Furthermore, for computations requiring large grid size (large macromolecular assemblages), the approach of memory distribution is shown to reduce the requirement of RAM and thus permitting large-scale modeling to be done on Linux clusters with moderate architecture. The new release comes with new features, whose functionalities and applications are described as well. © 2019 The Authors. Journal of Computational Chemistry published by Wiley Periodicals, Inc. 相似文献
50.
John J. Meister Damodar R. Patil Larry R. Field John C. Nicholson 《Journal of polymer science. Part A, Polymer chemistry》1984,22(9):1963-1980
Free radical polymerization of 2-propenamide in the presence of lignin, anhydrous calcium chloride, and cericion in photolyzed dioxane solvent produces a reaction product containing lignin-(1-amidoethylene) graft copolymer. Up to 49 weight percent of the product is poly(1-amidoethylene) homopolymer. Photolysis products of dioxane and the presence of anhydrous calcium chloride are critical to the reaction. A maximum yield of polymer is obtained when the dioxane solvent is irradiated for 3 h in a Pyrex vessel and the reaction mixture contains 2.0 weight percent calcium chloride. Aqueous size exclusion chromatography of reaction products shows that the molecular size of the lignin-(2-propenamide) reaction product is significantly greater than that of unreacted lignin, that the side chain and the lignin backbone migrate as one unit through the column, and that mixtures of lignin and poly(1-amidoethylene) are easily separated by the chromatographic column. 相似文献