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排序方式: 共有247条查询结果,搜索用时 52 毫秒
91.
We prepare CdS/CdSe/ZnS thin films by successive ionic layer adsorption and reaction method. Results show a wider photoresponse range of TiO2 mesopores from the ultraviolet region to the visible light region. Sequentially assembled CdS/CdSe/ZnS quantum and photocurrent efficiency. A high efficiency of dots exhibit significantly improved light-harvesting ability 1.059354% is obtained. 相似文献
92.
Tran?Duc?ThiepEmail author Truong?Thi?An Phan?Viet?Cuong Nguyen?Tuan?Khai Nguyen?The?Vinh A.?G.?Belov O.?D.?Maslov 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):637-645
We have determined the isomeric ratios in 120Te(γ, n)119m,gTe, 122Te(γ, n)121m,gTe, 128Te(γ, n)127m,gTe and 130Te(γ, n)129m,gTe photonuclear reactions of natural tellurium induced by bremsstrahlungs with end-point energies in the giant dipole resonance
(GDR) region. The investigated samples were irradiated at electron accelerator Microtron MT-25 of the Flerov Laboratory of
Nuclear Reaction, Joint Institute for Nuclear Research, Dubna, Russia. The gamma spectra of the samples irradiated were measured
with spectroscopic system consisting of 8192 channel analyzer and high-energy resolution (180 keV at gamma ray 1,332 keV of
60Co) HP(Ge) semiconductor detector Canberra. The GENIE2000 (Canberra) computer program was used for data processing. The results
were discussed and compared with those of other authors. 相似文献
93.
Bridge cleavage reactions of the dimeric monocarbene complex [PdBr(2)((i)Pr(2)-bimy)](2) can be effectively used to end-cap pyridine containing pseudorotaxanes affording stable [2]rotaxanes. 相似文献
94.
Nguyen VS Elsamra RM Peeters J Carl SA Nguyen MT 《Physical chemistry chemical physics : PCCP》2012,14(20):7456-7470
We investigated the rate constants and reaction mechanism of the gas phase reaction between the ethynyl radical and nitrous oxide (C(2)H + N(2)O) using both experimental methods and electronic structure calculations. A pulsed-laser photolysis/chemiluminescence technique was used to determine the absolute rate coefficient over the temperature range 570 K to 836 K. In this experimental temperature range, the measured temperature dependence of the overall rate constants can be expressed as: k(T) (C(2)H + N(2)O) = 2.93 × 10(-11) exp((-4000 ± 1100) K/T) cm(3) s(-1) (95% statistical confidence). Portions of the C(2)H + N(2)O potential energy surface (PES), containing low-energy pathways, were constructed using the composite G3B3 method. A multi-step reaction route leading to the products HCCO + N(2) is clearly preferred. The high selectivity between product channels favouring N(2) formation occurs very early. The pathway corresponds to the addition of the terminal C atom of C(2)H to the terminal N atom of N(2)O. Refined calculations using the coupled-cluster theory whose electronic energies were extrapolated to the complete basis set limit CCSD(T)/CBS led to an energy barrier of 6.0 kcal mol(-1) for the entrance channel. The overall rate constant was also determined by application of transition-state theory and Rice-Ramsperger-Kassel-Marcus (RRKM) statistical analyses to the PES. The computed rate constants have similar temperature dependence to the experimental values, though were somewhat lower. 相似文献
95.
The preparation and properties of mono- versus bis(carbene) Pd(II) complexes bearing unsymmetrical cyano- and ester-functionalized NHC ligands as potential IR probes were studied in detail. Direct reaction of Pd(OAc)2 with functionalized imidazolium salts afforded either bis(carbene) (3a, c) or monocarbene complexes (5, 6) with a N-coordinated imidazole co-ligand. The latter were exclusively obtained with N-ethylene substituted salts, which were found to undergo N-C cleavage reaction. The milder Ag-carbene transfer reaction on the other hand was tolerable to the length of the substituents and the nature of the functional groups. All bis(carbene) complexes (3a-c, 4a-c) were obtained as a inseparable mixture of square-planar trans-anti and trans-syn rotamers. The identity, ratio and dynamic equilibrium of these rotamers have been investigated and the relatively high rotational barrier for rotamers of 3a was estimated to be about 74 kJ mol−1 at 380 K. All eight complexes were fully characterized by NMR and IR spectroscopies, ESI mass spectrometry and X-ray single crystal and powder diffraction. A preliminary catalytic study showed that ester-functionalized complexes 4a and 4b gave rise to highly active catalyst in the double Mizoroki-Heck coupling of aryl dibromides, while the in situ ester-hydrolyzed complexes were also active in the coupling of activated aryl chlorides. 相似文献
96.
N. T. Khai T. D. Thiep T. T. An P. V. Cuong N. T. Vinh Yu. P. Gangrski G. V. Mishinski V. I. Zhemenik Sh. Gerbish A. G. Belov O. D. Maslov 《Physics of Particles and Nuclei Letters》2010,7(1):17-20
The photonuclear reactions of (γ, xn) or (γ, xnp) types can be used to produce high-intensity neutron sources for research and applied purposes. In this work a Monte-Carlo calculation has been used to evaluate the production yields of neutrons from the (γ, n) and (γ, 2n) reactions following the bremsstrahlung produced by 100 and 200 MeV electron beams on the tungsten target. Our calculations indicated that the neutron yield is an increasing function of the target thickness in a considered range from 1.5 to 2.5 mm. 相似文献
97.
Le Ba Vinh Nguyen Thi Minh Nguyet Jang Hoon Kim Nguyen Van Thanh Nguyen Xuan Cuong 《Natural product research》2019,33(5):628-634
Using various chromatographic separations, sixteen compounds, including one new triterpene saponin named aegicoroside A (1), were isolated from the leaves of the Vietnamese mangrove Aegiceras corniculatum. Their structures were determined by spectroscopic methods such as 1D and 2D NMR and HR-ESI-MS. The cytotoxic activities of the isolated compounds against MCF7 (breast), HCT116 (colon), B16F10 (melanoma), and A549 (adenocarcinoma) cancer cell lines were also evaluated. Strong cytotoxicity was observed for sakurasosaponin (2) against all four cancer cell lines and for sakurasosaponin methyl ester (3) against MCF7, A549, and HCT116 cell lines with IC50 values ranging from 2.89 ± 0.02 to 9.86 ± 0.21 μM. 相似文献
98.
Andreas Fouras David Lo Jacono Chuong Vinh Nguyen Kerry Hourigan 《Experiments in fluids》2009,47(4-5):569-577
A method is proposed that allows three-dimensional (3D) two-component measurements to be made by means of particle image velocimetry (PIV) in any volume illuminated over a finite thickness. The method is based on decomposing the cross-correlation function into various contributions at different depths. Because the technique is based on 3D decomposition of the correlation function and not reconstruction of particle images, there is no limit to particle seeding density as experienced by 3D particle tracking algorithms such as defocusing PIV and tomographic PIV. Correlations from different depths are differentiated by the variation in point spread function of the lens used to image the measurement volume over that range of depths. A number of examples are demonstrated by use of synthetic images which simulate micro-PIV (μPIV) experiments. These examples vary from the trivial case of Couette flow (linear variation of one velocity component over depth) to a general case where both velocity components vary by different complex functions over the depth. A final validation—the measurement of a parabolic velocity profile over the depth of a microchannel flow—is presented. The same method could also be applied using a thick light sheet in macro-scale PIV and in a stereo configuration for 3D three-component PIV. 相似文献
99.
Micro PIV uses volume illumination; therefore, the velocity measured at the focal plane is a weighted average of the velocities
within the measurement volume. The contribution of out-of-focus particles to the PIV correlation can generate significant
measurement errors particularly in near wall regions. We present a new application of image overlapping, which is shown to
be very effective in improving the accuracy of time-averaged velocity measurements by effectively reducing the measurement
depth. The performance of image overlapping and correlation averaging were studied using synthetic and experimental images
of micro channel flow, both with and without image pre-processing. The results show that for flows without particle clumping,
image overlapping provides the best measurement accuracy without any need for image pre-processing. For flows with particle
clumping, image overlapping combined with band-pass filtering provides the best measurement accuracy. When overlapped images
are saturated with particles due to a large number of image pairs, image overlapping measurement still does not show any visible
pixel-locking effect. Image overlapping was found to have comparable or slightly reduced pixel-locking effects compared to
correlation averaging. In addition, image overlapping utilizes significantly fewer computational resources than the other
techniques. 相似文献
100.
A versatile and rapid coating method via a combination of plasma polymerization and surface‐initiated SET‐LRP for the fabrication of low‐fouling surfaces 下载免费PDF全文
Yue Shi Donna J. Menzies Kelly M. Tsang Mark P. Del Borgo Christopher D. Easton Marie‐Isabel Aguilar Patrick Perlmutter Vinh X. Truong John S. Forsythe 《Journal of polymer science. Part A, Polymer chemistry》2017,55(15):2527-2536
In this work, we demonstrate the potential of surface‐initiated single electron transfer living radical polymerization for surface modification applications that confer low‐fouling properties. The versatility of the technique, which can be applied to a wide variety of substrates, has been displayed by the successful grafting of a range of monomers after immobilizing a bromine initiator on the surface via plasma polymerization. The thickness of the grafted surfaces can be controlled through variation of reaction parameters such as monomer concentration, reaction time, and the ratio between catalyst and ligand. Furthermore, the low‐fouling properties of the resulting surfaces were demonstrated against fully concentrated serum proteins and adhesive fibroblast cells, via grafting of N‐hydroxyethyl acrylamide (N‐HEA) or [2‐(methacryloyloxy)ethyl]dimethyl‐(3‐sulfopropyl) ammonium hydroxide (SBMA). This rapid and versatile coating technique, which has the ability to be applied to a wide range of substrates, can be performed in aqueous conditions without the exclusion of atmospheric oxygen, and shows excellent potential for the surface modification of biomaterial surfaces that require low‐fouling properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2527–2536 相似文献