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301.
外调制光纤有线电视发射机中一般采用预失真补偿技术以提高其复合三阶差拍失真指标。分析了在此情形下入射偏振对发射机复合三阶差拍失真补偿特性的影响 ,分析计算显示 :入射光偏振态模式为TE模时系统复合三阶差拍失真补偿特性最佳。对入射偏振态偏离TE模的情形的理论分析与实验研究表明 :为保证发射机的复合三阶差拍失真性能 ,入射光偏离TE模的角度应小于 15° 相似文献
302.
303.
掺杂La2O3的硫酸钛在缩醛(酮)反应中的催化活性 总被引:4,自引:1,他引:3
硫酸钛掺杂La2O3后经高温焙烧制得一种新型固体酸催化剂。用环己酮缩乙二醇反应表征其催化活性的反应条件为:环己酮200mmol,n(环己酮):n(乙二醇)=1.0:1.5,带水剂环己烷15mL,硫酸钛催化剂[w(La2O3)0.05,400℃焙烧3h]用量4.1%(以环己酮质量计),回流分水1h,收率94.5%。结果表明,催化活性随La2O3含量的增加而升高,随焙烧温度的升高而降低。催化剂吸附吡啶的红外光谱证实催化剂表面存在明显的Broensted酸中心和Lewis酸中心。该催化剂对其它缩醛(酮)反应也有催化活性。 相似文献
304.
Kun Xu Guoyin Lai Zhenggen Zha Susu Pan Prof. Dr. Huanwen Chen Prof. Dr. Zhiyong Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(39):12357-12362
A highly anti‐selective asymmetric Henry reaction has been developed, affording synthetically versatile β‐nitroalcohols in a predominately anti‐selective manner (mostly above 15:1) and excellent ee values (mostly above 95 %). Moreover, the anti‐selective Henry reaction was carried out in the presence of water for the first time with up to 99 % ee. The catalytic mechanism was proposed based on the detection of the intermediates by extractive electrospray ionization mass spectrometry (EESI‐MS). Furthermore, the anti adducts have been successfully transformed into the biochemically important (+)‐spisulosine and a pyrroloisoquinoline derivative. 相似文献
305.
Sheng Li Huai-Wu Zhang Qi-Ye Wen Yuan-Qiang Song Yun-Song Xie Wei-Wei Ling Yuan-Xun Li Jie Zha 《Infrared Physics & Technology》2010,53(1):61-64
Utilizing a series of micro-fabrication processes for terahertz meta materials, we fabricated three geometries of split-ring resonators: a circular geometry and two elliptical geometries. The samples were measured by the transmission spectroscopy in the terahertz time domain. Comparing these spectra, we found that these plots clearly reveal the lower frequency LC resonances and the higher frequency dipole resonances, meanwhile, the coupling of the LC and dipole resonance has an important influence on the overall response. It is shown that we can design the LC and dipole resonance frequency, and regulate the coupling of the LC and dipole resonance to adjust the overall response. A simple transmission-line RLC circuit model is used to help us understand this coupling behavior and the extent of its effects. 相似文献
306.
307.
Kan Luo Xian-Hu Zha Yuhong Zhou Qing Huang Shenghu Zhou Shiyu Du 《International journal of quantum chemistry》2020,120(24):e26409
MXenes have attracted intensive attention in chemistry and material science for their special structures and properties. In order to understand the basic physical properties of the M3C2/M3C2T2 (MSc, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W; TF, O, OH) MXenes, first-principles calculations are carried out to investigate the structural, vibrational, and mechanical properties in this work. Both the metal atoms and surface groups can significantly influence the configurations or mechanical behaviors of the MXenes. The dehydrogenation tendency is calculated to evaluate the possible forms of the M3C2(OH)2 toward M3C2O2. The work functions of MXenes functionalized by different groups are compared, and the lower work functions for the OH functionalized ones, which can be as low as 1.358 eV for the Sc3C2(OH)2, suggest potential good performance in electron emission. In addition, the stability, mechanical properties, and the Raman and infrared (IR) activity modes of the MXenes are reported. Generally, functionalized MXenes would present smaller lattice parameters, lower free energies, and stronger mechanical strength compared to their counterparts. The data obtained may provide important theoretical ground for the investigations of the applications of MXenes. 相似文献
308.
Dan Wen Shule Sun Ying Liu Jienan Li Zedeng Yang Aliye Kureshi Yan Fu Henan Li Bowei Jiang Chuan Jin Jifeng Cai Lagabaiyila Zha 《Electrophoresis》2021,42(9-10):1115-1126
The flanking region variants of nonbinary SNPs and phenotype-informative SNPs (piSNPs) have been observed, which may greatly improve the discriminative ability after constituting microhaplotype. In this study, 30 microhaplotype loci based on the nonbinary SNPs and piSNPs (shown to be related to phenotypes such as hair and eye color) were selected. Genotyping were conducted on 100 unrelated northern Han Chinese, and the 26 populations from the 1000 Genome Project were also included for comparison of populations differentiation. The simulated study was conducted for evaluating the efficiency of kinship testing. These 30 microhaplotype loci we selected had good polymorphism, with a mean effective number of alleles (Ae) of 3.46. The average Ae increase was 1.27 compared with the target SNPs. The populations from the five regions worldwide could also be distinguished using these loci. The results of kinship testing showed that these microhaplotype loci had the similar ability as 15 STR loci of AmpFlSTRR IdentifilerR PCR Amplification Kit to identify the biological parent and a stronger ability to exclude the nonbiological parents. So, these 30 microhaplotype loci may be multifunctional for forensic application, including the ability of personal identification and kinship testing equivalent to 15 STR loci, and the power of ancestry inference for distinguishing the main intercontinental population. Moreover, our selected phenotypic microhaplotype loci may theoretically have phenotype prediction capabilities. But the phenotype prediction efficiency of these phenotypic microhaplotype loci may be worse than that of piSNPs and the detailed prediction accuracy of different populations needs to be further studied. 相似文献
309.
Abstract
Assembly of orotic acid (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid, H3dtpc) and Cd(OAc)2·2H2O gave rise to two complexes [Cd2(H2dtpc)2(H2O)6] (I) and [Cd(H2dtpc)(bpy)(H2O)]n (II) (bpy = 2,2′-bipyridine). Complex (I) and (II) have been characterized by X-ray single crystal diffraction, IR, PXRD, TGA and fluorescence spectra. Structural analyses reveal that (I) is a binuclear structure, and complex (II) possesses a one-dimensional infinite zig-zag chain architecture and the chains are further assembled into 2D supramolecular network by strong hydrogen bonding interactions. Crystal data for (I): Monoclinic, space group P2(1)/n, a = 9.3221(19) ?, b = 6.6315(13) ?, c = 15.322(3) ?, β = 102.31(3)°, V = 925.4(3) ?3, Z = 4, R1 = 0.0269, and wR2 = 0.0604; for (II): Monoclinic, space group P2(1)/c, a = 9.9880(2) ?, b = 14.5085(2) ?, c = 11.6957(2) ?, β = 107.976(2)°, V = 1612.10(5) ?3, Z = 4, R1 = 0.0234 and wR2 = 0.0554. 相似文献310.
Y Zha HD Thaker RR Maddikeri SP Gido MT Tuominen GN Tew 《Journal of the American Chemical Society》2012,134(35):14534-14541
It was recently shown that block copolymers (BCPs) produced room-temperature ferromagnetic materials (RTFMs) due to their nanoscopic ordering and the cylindrical phase yielded the highest coercivity. Here, a series of metal-containing block-random copolymers composed of an alkyl-functionalized homo block (C(16)) and a random block of cobalt complex- (Co) and ferrocene-functionalized (Fe) units was synthesized via ring-opening metathesis polymerization. Taking advantage of the block-random architecture, the influence of dipolar interactions on the magnetic properties of these nanostructured BCP materials was studied by varying the molar ratio of the Co units to the Fe units, while maintaining the cylindrical phase-separated morphology. DC magnetic measurements, including magnetization versus field, zero-field-cooled, and field-cooled, as well as AC susceptibility measurements showed that the magnetic properties of the nanostructured BCP materials could be easily tuned by diluting the cobalt density with Fe units in the cylindrical domains. Decreasing the cobalt density weakened the dipolar interactions of the cobalt nanoparticles, leading to the transition from a room temperature ferromagnetic (RTF) to a superparamagnetic material. These results confirmed that dipolar interactions of the cobalt nanoparticles within the phase-separated domains were responsible for the RTF properties of the nanostructured BCP materials. 相似文献