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991.
F. Ditrói F. Tárkányi S. Takács M. S. Uddin M. Hagiwara M. Baba A. Ignatyuk S. F. Kovalev 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):835-841
Activation data of lead are of great importance due to the widespread applications of this element in various technological
fields and to the well known adverse effects to biological systems. Use of high sensitivity radioanalytical techniques allows
study of uptake, distribution and speciation. Cross sections of deuteron induced nuclear reactions on lead were measured up
to 40 MeV using the standard stacked foil irradiation technique and high resolution gamma-ray spectrometry. Experimental cross
sections and derived integral yields are reported for the natPb(d,xn)203,204,205,206,207Bi, natPb(d,x)203Pb202Tl reactions. Only one set of experimental cross section data was found in the literature. The experimental data are analyzed
and compared with the results of the theoretical model code ALICE-IPPE and with the experimental integral yield reported in
the literature. 相似文献
992.
Seiji Kurihara Teppei Yoshioka Tomonari Ogata Alam Md Zahangir Takamasa Nonaka 《Liquid crystals》2013,40(10):1219-1223
We have synthesized azobenzene-based molecules containing either one or two chiral groups. A cholesteric phase can be induced by adding the chiral azobenzene compounds to a host nematic liquid crystal. We investigated the effects of the trans-cis photoisomerization of the chiral azobenzene compounds on the properties of the cholesteric phase, such as the helical pitch length. This can be increased or decreased by the photoisomerization of the chiral azobenzene compounds. We discuss the photochemically driven change in the helical pitch of the cholesteric phase with respect to structural effects involving the chiral groups. 相似文献
993.
Two designs of long-wavelength band erbium-doped fiber amplifier (L-band EDFA) for gain clamping in double-pass systems are
demonstrated and compared. The first design is based on ring laser technique where a backward amplified spontaneous emission
(ASE) from the second stage is routed into the feedback loop to create an oscillating laser for gain clamping. The gain is
clamped at 18.6 d B from -40 to -80 dBm with a gain variation of less than ±0.1 dB and a noise figure of less than 6 dB. Another
scheme is based on partial reflection of ASE into the EDFA, which is demonstrated using a narrowband fiber Bragg grating.
This scheme achieves a good gain clamping characteristic up to -12 dBm of input signal power with a gain variation of less
than ±0.3 dB from a clamped gain of 22 dB. The noise figure of a 1580 nm signal is maintained below 5 dB in this amplifier
since this scheme is not based on lasing mechanism. The latter scheme is also expected to be free from the relaxation oscillation
problem. 相似文献
994.
Jeffrey S. Fu Md. Nurunnabi Mollah Nemai C. Karmakar 《International Journal of Infrared and Millimeter Waves》2006,27(4):571-589
A microstrip transmission line on a Chebyshev distributed chirped I-D photonic bandgap structure (PBGS) is proposed. Two different approaches are utilized to realize Chirped
PBGS. Firstly, the inter-element distance of PBG elements is chirped with conventional chirping technique. Secondly, using
Chebyshev distribution varies the inter-element distance. For both the cases, the amplitude is made non-uniform by varying the amplitudes
in accordance with the co-efficient of Chebyshev distribution. It can be seen that the conventionally chirped PBGS having Chebyshev distribution in amplitude improves the over all performance. The inclusion of Chebyshev distribution in period calculation further improves the performance. It can be seen that the Chirped and non-uniform PBGS
generates excellent bandgap performances in lower valued height of substrate that are superior to the performances available
in the open literature. 相似文献
995.
The problem of simultaneous estimation of the regression parameters in a multiple regression model with measurement errors is considered when it is suspected that the regression parameter vector may be the null-vector with some degree of uncertainty. In this regard, we propose two sets of four estimators, namely, (i) the unrestricted estimator, (ii) the preliminary test estimator, (iii) the Stein-type estimator and (iv) the postive-rule Stein-type estimator. In an asymptotic setup, properties of these estimators are studied based on asymptotic distributional bias, MSE matrices, and risks under a quadratic loss function. In addition to the asymptotic dominance of the Stein-type estimators, the paper contains discussion of dominating confidence sets based on the Stein-type estimation. Asymptotic analysis is considered based on a sequence of local alternatives to obtain the desired results. 相似文献
996.
997.
Muhamad Nasir Hidetoshi Matsumoto Tetsuya Danno Mie Minagawa Toshihira Irisawa Masatoshi Shioya Akihiko Tanioka 《Journal of Polymer Science.Polymer Physics》2006,44(5):779-786
Poly(vinylidene fluoride) (PVDF) nanofibers were prepared by electrospray deposition (ESD). To control the diameter, morphology, and structure of PVDF nanofibers, some parameters were investigated, such as polymer concentration, nozzle‐to‐ground collector distance, feeding rate of the polymer solution, and applied voltage. The fabricated fiber was 80–700 nm in diameter. The increase in the polymer concentration caused an increase in the polymer viscosity and fiber diameter. At low polymer concentration (5 wt %), polymer nanoparticles were formed. An increase in applied voltage will increase the fiber diameter. Variation in the nozzle‐to‐ground collector distance did not result in significant changes in the fiber diameter. Increase in the feeding rate of the polymer solution decreased the fiber diameter. Differential scanning calorimetry (DSC) and wide angle X‐ray diffraction (WAXD) measurements showed that the melting point and total crystallinity were decreased. Fourier transform infrared spectroscopy (FTIR) measurement revealed that ESD process induced the formation of the oriented β‐phase PVDF structures. It was also demonstrated that the addition of hydrofluorocarbon solvent to polymer solution remarkably enhanced the formation of β‐phase crystalline structure of PVDF nanofiber. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 779–786, 2006 相似文献
998.
The evaluation of a simple and rapid tristimulus colorimetric method for the determination of arsenic in brackish waters and its application to brackish water samples taken from brackish Lake Nakaumi are described. The determinations of arsenic in brackish water samples were made satisfactorily independent of sample salinity. By applying this method to lake water samples, the distributions and behaviors of arsenic in the lake and their controlling factors were clarified, such as seasonal variations of arsenic and the effect of a typhoon. 相似文献
999.
Wiley P. Kirk Kevin Clark Eduardo Maldonado Nasir Basit Robert T. Bate Gregory F. Spencer 《Superlattices and Microstructures》2000,28(5-6)
Epitaxial films of the wide-bandgap II–VI beryllium chalcogenide semiconductors, BeTe, BeSe, and BeSeTe were grown on arsenic-terminated silicon substrates by MBE. Silicon was also epitaxially regrown on Be-chalcogenide films. Initial structural characterization revealed the desired smooth two-dimensional nature of the layer growth. The composition of BeSeTe ternary films was governed by the Be/Se flux ratio during deposition rather than by the Se/Te flux ratio. The variation in Be/Se flux ratio or in the sticking coefficients due to temperature gradients led to radial compositional inhomogeneity. Current versus temperature measurements of the Be-chalcogenide films at elevated temperatures analyzed assuming thermionic emission over the heterojunction barrier, showed conduction band offsets of 1.2 eV for the BeSe0.41Te0.59/As/Si and 1.3 eV for the BeSe/As/Si heterostructures. At room temperature, current density through BeSe/Si and BeSe0.41Te0.59/Si films was mid-10 − 9A cm − 2at 0.1 MV cm − 1, similar to previously reported values for ZnS/Si, while BeTe/Si films had orders of magnitude higher current density, possibly due to interfacial recombination. 相似文献
1000.