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101.
Propagation characteristics of a segmented cladding fiber 总被引:3,自引:0,他引:3
We propose a novel optical fiber design that consists of a uniform core and a segmented cladding formed by alternate regions of high and low refractive indices in the azimuthal direction. The structure is analyzed by use of the radial effective-index method, and the propagation characteristics of the structure are studied. The fiber has a highly dispersive cladding and shows characteristics similar to those of photonic-crystal fibers and holey fibers. The novel fiber offers the possibility of single-mode operation over a wide range of wavelengths with a large core diameter. 相似文献
102.
A high concentration (0.8 M) zirconium solution turned into a stable aqueous colloid of about 60 nm in size upon low temperature (96°C) incubation. Changing the acid concentration did not affect the colloidal growth rate nor the final colloid size much. However, the induction time before the rapid growth of colloidal particle could be altered. By limiting the incubation to just before the rapid growth of colloidal zirconia, and the addition of organic acids as surface modifiers, non-agglomerated primary crystallites (10 nm) of m-ZrO2 could be recovered. These modified primary crystallites could then be repeatedly flocculated and redispersed in water by adjusting the pH. 相似文献
103.
A device of multiple nano-TiO2 layers was proposed and fabricated to prevent a dye/nano-TiO2 region from serious photo-degradation. In this device, the top of the dye/TiO2 region was designed to be coated using sol-gel nano-TiO2 thin films to shield UV irradiation from the photo-degradation effect. The sol-gel TiO2 was prepared in a low temperature (75 °C) and verified as nano-sized particles and an anatase crystalline structure. Different devices of the multi-layer samples fabricated using different compositions of nano-TiO2 were produced and exposed for UV irradiation tests. Results show that the presence of the sol-gel TiO2 films coated on top of the dye/TiO2 region can significantly alleviate the dye photo-degradation under UV irradiation. This multi-layer device can effectively improve the photo-stability of the dye/TiO2 region in a UV-exposure environment. 相似文献
104.
Ching-Yuan Chiang Madan L. Puri 《Annals of the Institute of Statistical Mathematics》1984,36(1):35-50
Summary In the linear regression modelX
i=α+βci+Zi, we consider the problem of testing the subhypothesis that some (but not all) components of β are equal to 0. A class of
asymptotically distribution-free tests based on a quadratic form in aligned rank statistic is studied and the asymptotic relative
efficiencies of the proposed tests with respect to the general likelihood ratio test and the test based on least-squares estimates
of regression parameters are derived. Asymptotic optimality (à la Wald) is also discussed.
Work done under the National Science Foundation Grant MCS 8301409 and NATO Grant 1465. 相似文献
105.
We describe identification of seven components from Antrodia cinnamomea. Their structures were determined on the basis of spectral analysis and comparison with authentic samples. These compounds include two steroids (1, 2) (β-sitosterol and eburicol), two new steroids (3, 4) [methyl-4α-methylergost-8,24(28)-dien-3,7,11-trion-26-oate and methyl-4α-methylergost-8,24(28)-dien-3,11-dion-26-oate], two lignans (5, 6) [(+)-sesamin and 4-hydroxysesamin], and one long chain methyl ester (7) (methyl oleate). Among them, compounds 3 and 4 are first isolated from nature. 相似文献
106.
A study of the adsorptive stripping voltammetry of nickel, aluminium, selenium and arsenic is reported in which 2,5-dimercapto-1,3,4-thiadiazole (DMTD) has been used as a chelating agent. By a suitable choice of deposition potential, deposition time, reagent reaction time and other operating conditions, the determination of the four elements could be achieved.By the use of benzyltrimethyl ammonium methoxide as a digesting solvent, it was possible to apply the procedure to the direct determination of the four elements in biological samples. 相似文献
107.
Diselenophosphate‐Induced Conversion of an Achiral [Cu20H11{S2P(OiPr)2}9] into a Chiral [Cu20H11{Se2P(OiPr)2}9] Polyhydrido Nanocluster 下载免费PDF全文
Dr. Rajendra S. Dhayal Jian‐Hong Liao Dr. Xiaoping Wang Dr. Yu‐Chiao Liu Dr. Ming‐His Chiang Dr. Samia Kahlal Prof. Jean‐Yves Saillard Prof. C. W. Liu 《Angewandte Chemie (International ed. in English)》2015,54(46):13604-13608
A polyhydrido copper nanocluster, [Cu20H11{Se2P(OiPr)2}9] ( 2H ), which exhibits an intrinsically chiral inorganic core of C3 symmetry, was synthesized from achiral [Cu20H11{S2P(OiPr)2}9] ( 1H ) of C3h symmetry by a ligand‐exchange method. The structure has a distorted cuboctahedral Cu13 core, two triangular faces of which are capped along the C3 axis, one by a Cu6 cupola and the other by a single Cu atom. The Cu20 framework is further stabilized by 9 diselenophosphate and 11 hydride ligands. The number of hydride, phosphorus, and selenium resonances and their splitting patterns in multinuclear NMR spectra of 2H indicate that the chiral Cu20H11 core retains its C3 symmetry in solution. The 11 hydride ligands were located by neutron diffraction experiments and shown to be capping μ3‐H and interstitial μ5‐H ligands (in square‐pyramidal and trigonal‐bipyramidal cavities), as supported by DFT calculations on [Cu20H11(Se2PH2)9] ( 2H′ ) as a simplified model. 相似文献
108.
Kun‐Heng Chiang Shi‐Han Lu Wan‐Ping Yen Naoto Uramaru Wei‐Siou Tseng Te‐Wei Chang Fung Fuh Wong 《Heteroatom Chemistry》2016,27(4):235-242
A convenient synthetic method for N‐arylformamide derivatives was successfully developed by reacting α‐iodo‐N‐arylacetamides with formamide. This method was applicable to α‐iodo‐N‐arylacetamide substrates bearing electron‐donating or electron‐withdrawing groups, N‐(benzo[d][1,3]dioxol‐5‐yl)‐2‐iodoacetamide, 2‐iodo‐N‐(pyridin‐2‐yl)acetamide, and 2‐iodo‐N‐(naphthalen‐4‐yl)acetamide to give the corresponding N‐arylformamides in moderate to excellent yields (65–94%). A plausible mechanism was proposed to account for the new transformation. 相似文献
109.
Tu‐Gen Xu Duan‐Jun Xu Jing‐Yun Wu Michael Y. Chiang 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(12):m615-m616
The title complex, {[Fe(C4H4O4)(H2O)4]}n, is an infinite polymeric compound bridged by the succinate dianion. Two carboxylate groups coordinate in a monodentate manner to the FeII atom, in a trans fashion, with an O—Fe—O bond angle of 175.72 (6)° and Fe—O distances of 2.0886 (14) and 2.1008 (15) Å. One of the uncoordinated carboxylate O atom forms an intramolecular hydrogen bond with a coordinated water molecule. Extensive hydrogen bonding between parallel polymeric complex chains results in a three‐dimensional supramolecular structure. 相似文献
110.