Integrating spin-based technologies with atomically controlled van der Waals interfaces

As the feature sizes of electronic devices continue to shrink, new technologies—in particular spintronics and derived interfacial architectures—become increasingly pivotal. In this context, two-dimensional van der Waals materials and their interfaces are particularly attractive, relying on their ultimate atomic thicknesses and exceptional spin-related properties. This review provides a critical evaluation on the state-of-the-art of van der Waals interfaces and projected technological applications in spintronics, highlights major challenges and a viable solution—an all-in-situ growth and characterization strategy, and finally identifies several emerging spin-based technologies that might significantly benefit from the versatile van der Waals interfaces enabled by the strategy.     

橡胶的红外光谱分析

本文报导了天然橡胶、合成异戊二烯橡胶、顺丁、丁苯、丁腈、丁基、氯丁和乙丙等八种橡胶的红外光谱分析。     

关于1990年国际温标(ITS—90)

自1990年元旦开始,1990年国际温标(TTS-90)已取代1968年国际实用温标(IPTS-68、1975年修订版)。本文评述了制订 ITS-90的背景,以及与 IPTS-68相比它在准确性、一致性和光滑性等方面的重大改进。这里还对 ITS-90的构成进行了分析,并对它可能达到的准确度作出讨论。文章也指出了为贯彻 ITS-90所涉及到的一些问题。     

聚硼硅氧烷的合成及其流变性能EI北大核心CSCD

为了探究聚硼硅氧烷(PBDMSs)的物理交联网络结构对体系黏弹性的影响,将不同羟基含量的端羟基聚二甲基硅氧烷(PDMS)分别与硼酸进行反应,制备不同硼化交联密度的PBDMSs,并对合成的PBDMSs的结构、热力学及流变性能进行表征。结果表明:制备的PBDMSs中含有Si—O—Si,Si—O—B,CH_(3)—Si—CH_(3)和B—O—B结构单元;PBDMSs具有优异的耐低温性能,其玻璃化转变温度随着原料PDMS中羟基含量的增加而升高,且当原料PDMS的羟基含量较低时(1%和2%,质量分数),生成物PBDMSs具有一定的结晶能力;PBDMSs具有频率敏感性的特征,并且具有良好的抗冲击能力、优异的阻尼耗散能力和出色的回弹性能,原料PDMS的羟基含量影响生成物PBDMSs的物理交联网络结构,进而对PBDMSs的动态模量有显著影响,实际应用时可根据需求改变PDMS的羟基含量来调节PBDMSs的黏弹性。     

Finding Applications for Materials

Well‐developed techniques exist to select a material for a given application. Solutions to the inverse problem—that of finding an application for a given (often new) material are more elusive. Here we explore strategies for finding potential applications. The first—the strategy of parasitical substitution—is effective when a new material (the parasite) has properties that resemble those of an established material (the victim) but is superior to it in one—cost, perhaps, or environmental acceptability, or processability. Then a match is sought between the property profile of the parasite and that of existing materials; those with a close match (ignoring the single unique property) are potential “victims”—their applications become the targets for the parasite, exploiting its uniqueness. The second—the strategy of systematic matching of design requirements—searches for a match between the property‐profile of the new material and the profiles (expressed as constraints on material property groups) of a library of applications. The third—the strategy of selection by function—makes use of an abstraction, that of the underlying function of the component and the material indices associated with it. The strengths and weaknesses of these are explored, and the context in which there success might be maximised is defined.     

含铍碳化硅陶瓷先驱体聚铍碳硅烷的合成

以氢氧化铍、硫酸和乙酰丙酮为原料合成了乙酰丙酮铍(Be(acac)2).用乙酰丙酮铍和聚碳硅烷在加热的条件下反应一定时间,生成了树脂状的产物.反应中乙酰丙酮铍被消耗,生成产物熔点相对起始聚碳硅烷熔点升高.元素分析表明产物中含有铍元素,凝胶渗透色谱分析表明产物分子量相对起始聚碳硅烷向增大的方向发生变化.傅立叶红外光谱分析表明产物中主要存在如下结构:Si(CH3)2—CH2—,—Si(CH3)·(H)—CH2—.核磁共振1H-NMR分析表明反应物中Si—H键被消耗.根据分析结果推测了反应机理,Si—H键的消耗在产物的形成中起了重要作用.实验与理论分析表明先驱体产物是一种含铍聚碳硅烷,可以命名为聚铍碳硅烷(PBeCS).在1200℃的高温处理下产物作为先驱体可以转化为碳化硅陶瓷,元素分析表明碳化硅陶瓷中含有铍,是含铍碳化硅陶瓷.     

一种潜在新型材料——真菌纤维的晶体结构表征

选用真菌合成了丝状微米真菌纤维素,通过扫描电子显微镜(SEM)、红外光谱(FT-IR)、固体核磁共振(CP/MAS 13C NMR)、X射线衍射(XRD)等分析方法对真菌产生的纤维进行了微观形貌和化学结构表征。SEM结果表明由真菌产生的纤维均为微米级,成条形纤维状,具有清晰的三维网状结构;FT-IR结果表明真菌纤维中可能含有—OH、—C—O—C、—CH2、—NH2等特征官能团,与棉花纤维素所含特征官能团相似;将真菌纤维的13 C NMR和XRD与天然纤维素以及细菌纤维素比较,发现真菌纤维的化学位移与细菌纤维素相似,含有较高的I晶型纤维素和非晶体化合物。真菌纤维有可能被用作模板剂或聚合物增强方面。     

Removal of phosphorus by the solidification refining with Si—Al melts

To discuss the possibility of phosphorus removal from silicon by the solidification refining with Si—Al melts, the distribution of phosphorus between solid silicon and the liquid Si—Al alloy at 1173—1373 K was investigated. In the present study, the distribution of phosphorus was examined by the temperature gradient zone melting method, where a phosphorus containing molten Si—Al zone was passed through a single crystalline silicon phase. The segregation ratio of phosphorus at its infinite dilution was obtained as 0.12 (1373 K), 0.085 (1273 K) and 0.061 (1173 K), respectively, and the solidification refining with the Si—Al melts was found to be effective for the removal of phosphorus at lower temperature.     

聚丙烯酰胺钕配合物的研究

首次引入稀土金属钕离子,合成聚丙烯酰胺钕[PAAM—Nd(Ⅲ)]配位聚合物,并用FT—IR、XPS、元素分析及电导率等分析手段对配合物进行表征,证明了Nd(Ⅲ)与PAAM的配位作用,并测出Nd(Ⅲ)与PAAM单体单元的配位比为1∶4。     

Advances in Molecular Electronics: A Brief Review

The field of molecular electronics, also known as moletronics, deals with the assembly of molecular electronic components using molecules as the building blocks. It is an interdisciplinary field that includes physics, chemistry, materials science, and engineering. Moletronics mainly deals with the reduction of size of silicon components. Novel research has been performed in developing electrical-equivalent molecular components. Moletronics has established its influence in electronic and photonic applications, such as conducting polymers, photochromics, organic superconductors, electrochromics, and many more. Since there is a need to reduce the size of the silicon chip, attaining such technology at the molecular level is essential. Although the experimental verification and modeling of molecular devices present a daunting task, vital breakthroughs have been achieved in this field. This article combines an overview of various molecular components, such as molecular transistors, diodes, capacitors, wires, and insulators, with a discussion of the potential applications of different molecules suitable for such components. We emphasize future developments and provide a brief review of different achievements that have been made regarding graphene-based molecular devices.     

Implantation of organic matter through water onto solid substrates by a laser induced molecular jet

Organic molecular dots were successfully produced by means of a nano second pulsed dye laser on glass and indium tin oxide (ITO) substrates, with sizes of several hundred nanometres. The method involves the transfer of organic molecules from the source Coumarin 6 (C6) and poly [2-methoxy, 5-(2′-ethyl-hexyloxy)-p-phenylene-venylene] (MEH-PPV) films onto a target material through a water filled space-gap using a laser induced molecular jet (LIMJ). In this way, the organic dots of Coumarin 6 and MEH-PPV molecules were successfully implanted onto the glass and ITO targets. The present results demonstrate the possibility to significantly improve photo electronic or photoelectric devices such as novel photonic crystal and molecular device sensors, and so on.     

Bisphenol A imprinted polymer adsorbents with selective recognition and binding characteristics

Imprinted copolymers, which highly recognized and bound bisphenol A (Bis A), were synthesized by using covalent imprinting technique. Bisphenol A dimethacrylate (BADM) was used as a template monomer in the copolymerization with a crosslinkable monomer of divinyl benzene (DVB), ethylene glycol dimethacrylate (EGDM) or N,N’-methylenebisacrylamide (MBAA). The resultant copolymer was hydrolyzed in acidic or basic condition. It was found that the Bis A imprinted copolymers of EGDM and MBAA had no selectivity to Bis A, because the crosslinker dissociated by the hydrolysis reaction and thus comprehensive imprinted sites were not formed. On the other hand, imprinted copolymer of DVB showed excellent selectivity to differentiate Bis A from bisphenol E and bisphenol F (Bis F). Characterization of the copolymers suggested that the DVB copolymer had resistance to the acid and alkali conditions. Effect of recognition by the Bis F imprinted polymer was also compared with that of the Bis A imprinted polymer, when DVB and bisphenol F dimethacrylate were copolymerized. The Bis F imprinted copolymer was able to recognize Bis F in ethanol solution, however showed higher binding capacity for both Bis A and Bis F in water solution without recognition. Therefore, hydrophobic interaction between Bis A and the imprinted site enhanced the binding capacity with high selectively for the BADM-co-DVB imprinted copolymer.     

PECVD非晶SiOx∶H薄膜的Si—O—Si键红外吸收特性研究

用傅里叶红外光谱(FT-IR)测试分析了等离子体化学气相沉积法沉积的非晶SiOx∶H(0≤x≤2.0)薄膜中的Si—O—Si伸缩振动模与氧含量x的关系。Si—O—Si伸缩振动模在1000和1150cm     

氢化物发生——原子荧光法测定土壤中砷的方法研究

建立氢化物发生--原子荧光法测定土壤中砷的方法,研究反应酸度、还原剂浓度、仪器条件等因素对测定的影响。在最佳条件下,测定土壤中砷的含量,该法操作简便、快速、准确、重复性好、灵敏度高。     

Comparison of mesenchymal stem cell proliferation and differentiation between biomimetic and electrochemical coatings on different topographic surfaces

The hypothesis for this study was that there is no difference in mesenchymal stem cells (MSCs) proliferation and osteogenic differentiation between calcium-phosphate (CaP) coatings with different crystal size deposited on different topographic surfaces of metal discs. Polished (P) and sand-blasted (SB) tantalum and TiAl6V4 discs were CaP coated by three methods—biomimetic (BioM), electrochemical at 20 mA/cm² and at 6.5 mA/cm²—and cultured with MSCs. At days 4, 7 and 14, cell proliferation—alamarBlue^® activity and DNA quantification—and differentiation down the osteogenic lineage—ALP activity normalised per amount of DNA and SEM (morphology)—were analysed. Results showed that MSCs proliferated more when cultured on the nano-sized BioM coatings compared to uncoated and electrochemically coated discs. MSCs also proliferated more on P surfaces than on SB and or electrochemical coatings. All the coatings induced osteogenic differentiation, which was greater on electrochemical coatings and SB discs.     

采用二维红外技术研究交联对碱溶胶原结构的影响

以N-羟基琥珀酰亚胺己二酸酯(NHS-AA)为交联剂,交联改性碱溶胶原,采用二维红外相关光谱法研究了交联对胶原二级结构的影响。研究发现,交联未影响胶原红外特征吸收峰的位置,但1672、1554和1241cm-1归属于胶原酰胺I带的CO伸缩振动、酰胺Ⅱ带的C—N伸缩与N—H弯曲振动和Ⅲ带的N—H面内变形振动峰之间存在同步正交叉峰,表明随交联共价键的增加,胶原的链段构象发生了变化。在NHS-AA用量增加的过程中,胶原二级结构变化的顺序为:酰胺Ⅲ带>酰胺Ⅰ带>酰胺Ⅱ带>—CH3>—CH—。由此可见,二维红外相关分析法能提供由交联引起的胶原构象动态变化的微观信息,为进一步研究改性胶原结构与功能之间的关系提供实验依据。     

Application of the Hydrogen Diffusion Model to the Hydrogen Permeation

The model of hydrogen diffusion formerly de-veloped [1] has been applied successfully to thehydrogen permeation experiment results of threekinds of materials,α—Fe,Fe—Ti alloy and Fe—Ti—Calloy by the mathematical fitting method.From thefitting results it was shown that the model can re-fiect well the diffusion of hydrogen in the materialswith trapping.The obtained trapping parameters(αand β)can be used to explain well the diffusion ofhydrogen in the samples with trapping.     

增效试剂在动力学分析法中的应用研究锰(Ⅱ)—高碘酸钾—氨三乙酸—PAN—Triton X—100催化体系

本文报道了以 Triton X—100为增溶剂,高碘酸钾氧化 PAN 催化光度法测定痕量锰的新体系。方法的检出限为3.6×10~(-3)μg/mL,精密度为2.4%(n=9),线性范围为0.10～1.3μg/25mL,可用于谷物样品中锰的测定。     

多模光纤温度传感器系统

研制了钴盐溶液热色传感介质光学双波长差分吸收多模光纤温度传感器系统。自制了光纤耦合器件,采用了锁相电路,利用微机直接进行数字锁相探测,信号相除运算和温度校正。该系统实时显示温度,测温范围30℃—50℃,准确度±0.15℃,分辨率0.02℃,在40℃时6小时稳定性±0.05℃,12小时稳定性±0.18℃。主要用于抗电磁干扰的微波辐射治疗和谷物加热干燥等测温应用。     

A total ALE FE formulation for axisymmetric and torsional problems (including viscoplasticity,thermodynamic coupling and dynamics)

This paper—first—extends a recent ‘assumed enhanced deformation gradient’ finite ring(segment) element (Int. J. Numer. Methods Eng. 2001; 50 :899–918.) to Arbitary Lagrange Euler (ALE) computations, by setting up the assumed tensor on the computational configuration, and—second—shows an elegant way of incorporating dynamics into real ALE computations (no splitting into purely—Lagrange steps and then—remeshing steps), by introducing material mesh velocities and accelerations and spatial mesh velocities and accelerations. Copyright © 2006 John Wiley & Sons, Ltd.