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51.
大截面单模半导体脊形交叉波导传输特性 总被引:8,自引:4,他引:4
运用光束传播法和有效折射率法分析了大截面单模半导体脊形交叉波导结构的传输特性,对Y形,X形和加宽X形结构进行了比较。结果表明,在小交叉角时,三种结构具有相似的传输特性;在大交叉角时,它们表现出较大的差异。而在Y型结构中,不存在模式干涉。 相似文献
52.
A four-component one-pot sequential synthesis of alpha-Gal pentasaccharide 2 with minimal protecting group manipulations in a very short period of time is described in this paper. [structure: see text] 相似文献
53.
Zhewen Guo Jun Zhao Yuhang Liu Guangfeng Li Heng Wang Yali Hou Mingming Zhang Xiaopeng Li Xuzhou Yan 《中国化学快报》2021,32(5):1691-1695
Herein, we designed and constructed two metallacycles, 1 and 2, to illustrate the conformational effect of isomeric AIE fluorophores on the platform of supramolecular coordination complexes (SCCs). Speci?cally, the dangling phenyl rings in TPE units of the metallacycle 1 align completely outside the main cyclic structure, while in the metallacycle 2, these phenyl rings align half inside and half outside. The experimental results showed that two metallacycles exhibited different behaviors in terms of AIE fluorescence and chemical sensing, which could be attributed to the subtle structural difference of the TPE units. This work represents the unification of topics such as self-assembly, AIE, and chemical sensing, and further promotes the understanding for the structure-property relationship of isomeric AIE fluorophores. 相似文献
54.
Coal bed methane(CBM) has a huge potential to be purified to relieve the shortage of natural gas meanwhile to weaken the greenhouse effect.This paper proposed an optimal design strategy for CBM to obtain an integrated process configuration consisting of three each single separation units,membrane,pressure swing absorption,and cryogenics.A superstructure model was established including all possible network configurations which were solved by MINLP.The design strategy optimized the separation unit configuration and operating conditions to satisfy the target of minimum total annual process cost.An example was presented for the separation of CH4/N2 mixtures in coal bed methane (CBM) treatment.The key operation parameters were also studied and they showed the influence to process configurations. 相似文献
55.
针对BT20钛合金锻件当量孔损伤进行激光沉积修复试验,考察了修复试样的组织和力学特点。修复区与基材之间形成了致密冶金结合,Al,Zr,Mo,V合金元素由锻件基体到激光修复区均匀分布,无宏观偏析,硬度分布从基材到修复区依次提高。热影响区组织是由基材的双态组织过渡到网篮组织;修复区组织为粗大的原始柱状β晶,晶粒内为α/β网篮组织,晶内α片层取向随机,宽0.4~0.5μm。修复过程中发现,激光加工工艺参数选择不当、坡度过大等原因会造成修复区组织形成气孔和熔合不良等缺陷,但是通过优化工艺参数可以获得无缺陷修复试样。修复试样的室温静拉伸结果表明,试样的抗拉强度接近锻件基体强度,但修复件的韧性比锻件稍有提高。 相似文献
56.
This paper proposes a novel method for reducing measurement error caused by spectrum overlapping in composite-structured-light 3D measurement systems. For a composite-structured-light 3D measurement system, spectrum overlapping causes parameters of each deformed phase-shifting fringe to change, and therefore leads to phase measurement errors. The proposed fringe parameter calibration method is based on the fact that variations in each deformed fringe's parameters are independent of height and reflectivity of the measured object. Three frames of composite grating are projected on the reference plane, and each carrier channel includes the information of three phase-shifting sinusoidal gratings used in Phase Measuring Profilometry (PMP). With the parameter calculation formulas of PMP, the parameters of fringes demodulated from the same carrier channel can be calculated, and therefore parameter relation coefficients between fringes demodulated from different carrier channels may be obtained. When an object is measured, these relation coefficients can be used to calibrate the parameters of the deformed phase-shifting fringes. A new 3D measurement mathematical model is established to reconstruct the shape of the object. Experimental data proved that the proposed method can effectively restrain the effect of spectrum overlapping and improve measurement accuracy by more than three times. 相似文献
57.
In this study, an electroplating method to deposited Ni, crystalline NiW(c-NiW), amorphous NiW (a-NiW) films on P-type Si(1 0 0) were used to form Ni-silicide (NiSi) films. After annealed at various temperatures, sheet resistance of Ni/Cu, c-NiW/Cu and a-NiW/Cu was measured to observe the performance of those diffusion barrier layers. With W added in the barrier layer, the barrier performance was improved. The results of XRD and resistance measurement of the stacked Si/Ni(W)/Cu films reveal that Cu atom could diffuse through Ni barrier layer at 450 °C, could diffuse through c-NiW at 550 °C, but could hardly diffuse through a-NiW barrier layer. c-NiW layer has a better barrier performance than Ni layer, meanwhile the resistance is lower than a-NiW layer. 相似文献
58.
pH-Responsive DNA assembles have drawn growing attentions owing to their great potential in diverse areas.However,pH-responsive motifs are limited to specific DNA sequences and annealing is usually needed for DNA assemblies;therefore,sequence-independent pH-responsive DNA assembly at room temperature is highly desired as a more general way.Here,we propose a reversible pH-responsive DNA assembly strategy at room-temperature using zwitterion,glycine betaine(GB),as charge-regulation molecules.The reversible assembly and disassembly of DNA nanostructures could be achieved by alternatively regulating the acidic and basic environments in the presence of GB,respectively.In an acidic environment,carboxylate group in GB was protonated and GB was positively charged,which facilitated to shield the inherent electrostatic repulsion of DNA strands.Molecular simulation showed that the newly formed carboxyl group in protonated GB could form hydrogen bonds with bases in DNA to promote the assembly of DNA strands.In a basic solution,carboxylate group in GB was deprotonated and GB was neutral,thus inducing the dissociation of DNA assembly. 相似文献
59.
Yuhang Liu Seckin Akin Alexander Hinderhofer Felix T. Eickemeyer Hongwei Zhu Ji‐Youn Seo Jiahuan Zhang Frank Schreiber Hong Zhang Shaik M. Zakeeruddin Anders Hagfeldt M. Ibrahim Dar Michael Grtzel 《Angewandte Chemie (International ed. in English)》2020,59(36):15688-15694
As a result of their attractive optoelectronic properties, metal halide APbI3 perovskites employing formamidinium (FA+) as the A cation are the focus of research. The superior chemical and thermal stability of FA+ cations makes α‐FAPbI3 more suitable for solar‐cell applications than methylammonium lead iodide (MAPbI3). However, its spontaneous conversion into the yellow non‐perovskite phase (δ‐FAPbI3) under ambient conditions poses a serious challenge for practical applications. Herein, we report on the stabilization of the desired α‐FAPbI3 perovskite phase by protecting it with a two‐dimensional (2D) IBA2FAPb2I7 (IBA=iso‐butylammonium overlayer, formed via stepwise annealing. The α‐FAPbI3/IBA2FAPb2I7 based perovskite solar cell (PSC) reached a high power conversion efficiency (PCE) of close to 23 %. In addition, it showed excellent operational stability, retaining around 85 % of its initial efficiency under severe combined heat and light stress, that is, simultaneous exposure with maximum power tracking to full simulated sunlight at 80 °C over 500 h. 相似文献
60.
Sulfone is prevalent in natural products and has been widely used in organic chemistry. Among the approaches of installing sulfonyl group, sulfonylation starting from stable and environmentally friendly sulfonyl sources is promising and attractive. Diverse mild sulfonyl sources such as DABSO, inorganic metal salts, sulfinic acids/salts, and sulfonyl hydrazides have been applied to construct sulfone. In this review, recent advances for the sulfonylation under transition metal catalysis and metal-free conditions are summarized. 相似文献