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21.
Six new title compounds in the form of Cd(cyclobutylamine)2M′(CN)4 · 2G (M′ = Cd or Hg; G = benzene, 1,2-dichlorobenzene, or 1,3-dichlorobenzene) have been prepared in powder form. Their spectral
data were found to be consistent with the structure of the Hofmann-T
d
-type clathrates. 相似文献
22.
Abstract— The photochemical reactions in concentrated thionine solution have been studied using continuous illumination. Thionine solution is photoreduced to leucothionine in an oxygen-free acidic medium. Electrochemical measurements of the photoreduction of thionine are reported. A possible reaction pathway for the energy transfer is proposed. It is found that polymeric forms of thionine and leucothionine are not involved in photoreduction. It is proposed that a complex must be formed prior to photochemical reduction. This complex species, having a lifetime of several seconds, is reduced to leucothionine, water being the reducing agent. Following this reduction, H2 O2 is formed and the production of H2 O2 is detected by differential pulse polarography. 相似文献
23.
G. E. Stratakos N. V. Vlassopoulos N. K. Uzunoglu C. N. Capsalis 《International Journal of Infrared and Millimeter Waves》1995,16(8):1367-1392
Millimeter wave frequencies are proposed as carriers of microcell future mobile systems. High frequencies in the region of 60–62 Ghz are suggested. A serious difficulty in this context is the lack of sufficient gain in active devices. Both on receiver and transmitter units this difficulty is faced. Mixing, amplification, carrier recovery and modulation / demodulation subsytems are required to be operational at these higher frequencies. Presently the MMIC 's show also limited performance. In this report an alternative approach active processing technique is examined based on an injection locking in Gunn oscillator. A non-linear analysis is applied to determine the fundamental properties of injection locking in Gunn oscillator performance under the influence of an external signal. Details of waveguide action is taken into account by solving the corresponding boundary condition problem. Finally experimental results are presented for a 30GHz oscillator. 相似文献
24.
Rıdvan Baldık Hüseyin Aytekin Mustafa Erer 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(2):297-302
In this work, the radionuclide activity concentrations of 226Ra, 232Th and 40K in surface soils and radon levels in dwellings of Karabük, Turkey were determined in order to evaluate the environmental
radioactivity. Concentrations of 226Ra, 232Th and 40K radionuclides were determined using gamma spectrometry with using HPGe detector. The etch track detectors (CR-39) were used
to determine the distribution of radon concentrations. The average activity concentrations for 226Ra, 232Th and 40K were found as 21.0, 23.5 and 363.5 Bq kg−1, respectively. The calculated average annual effective dose equivalent from the outdoor terrestrial gamma radiation from
226Ra, 232Th and 40K is 53.5 μSv y−1. The average radon concentration and annual effective dose equivalent of 222Rn in Karabük dwellings were obtained 131.6 Bqm−3 and 3.32 mSv y−1, respectively. The evaluated data were compared with the data obtained from different countries. 相似文献
25.
Chitosan (CH) is a biopolymer with biocompatible, biodegradable, and bioactive properties. N,N,N‐trimethyl chitosan chloride (TMC) is a quaternized form of CH that is highly cationic and more water soluble than unmodified CH. The physiological activities of CHs with different molecular weights (Mw) and degrees of TMCs quaternization were investigated in U937 and 3T3‐L1 cell lines. 1H‐NMR spectrometry and size exclusion chromatography were used for characterization of the biopolymers. The half inhibition concentration (IC50) of DPPH‐radical‐scavenging activity was below 0.9 mg/m with quaternized CHs. The IC50 values of chitooligosaccharides, low‐ and medium‐molecular‐weight CHs were 8.4, 10.9, and 13.9 mg/ml, respectively. High‐molecular‐weight CHs and TMCs showed apoptotic activity on U937 cells. T41, a TMC of 549 kDa with a 41% degree of quaternization (DQ), yielded 30.7% apoptotic cell death in U937 at 20 µg/ml and effectively repressed cell differentiation and triglyceride accumulation in 3T3‐L1. Depolymerized CHs reduced triglyceride accumulation but also caused cell differentiation. TMCs showed repressor activity to both cell differentiation and triglyceride accumulation. Increasing the molecular weight of CHs and TMCs generally resulted in increased physiological activity. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
26.
In this work, we have developed an analytical model of a multilayer porous material based on the transfer matrix method to predict the absorption behavior at plane wave incidence. The aim of this study is to modify/tune the sound absorption coefficient of a felt to obtain an improved absorbing performance in the mid frequency range without increasing its weight. To achieve this target, the developed model has been used to find the best combination of each layer type and thickness. The analytical results were validated by test results. 相似文献
27.
Turbulent two-phase flow equations are derived and solved for fully developed pipe flow using a composite eddy-viscosity model
and a new void-fraction equation. The void fraction profile is first specified from experiments and the velocity field is
calculated to validate the eddy-viscosity model. Consequently, a new equation is presented for calculation of the void fraction.
This void-fraction equation incorporates the gradient of turbulent normal stresses in the radial direction, the conventional
lift force, and a contribution from the unsteady drag force. The implications of this new equation, for the bubbly flow regime,
are investigated by calculating the void-fraction distribution for a given velocity field. Inclusion of the normal turbulent
stresses in the radial direction is shown to simulate correctly the experimentally observed trends of the phase distribution,
both for upward and downward bubbly flow, without the need for a fictitious term such as the so called ``lubrication force'.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
28.
N. K. Uzunoglu P. A. Mandis 《International Journal of Infrared and Millimeter Waves》1987,8(5):535-547
In this paper the coupling between two closely spaced single mode dielectric rod waveguides is investigated when the corresponding propagation axes are not in the same plane. An approximate analysis is presented by assuming only first order interaction between the guided waves. For a given incident HE11 mode (in one of the rod waveguides) the coupled wave amplitudes are computed in the other waveguide for both propagation directions. Numerical results are presented for several coupling geometries. 相似文献
29.
30.
In the presence of BF3, a series of symmetrical and unsymmetrical ethers reacted with epichlorohydrin and 2‐[(benzyloxy)methyl]oxirane, two terminal epoxides, to afford 1‐alkoxy‐3‐chloropropan‐2‐ol and 1‐alkoxy‐3‐(benzyloxy)propan‐2‐ol. The cleavage of unsymmetrical ethers occurred via an SN2 or SN1 mechanism. Secondary epoxides did not give similar ring‐opening products. 相似文献