Pseudo-Binary Phase Diagram of LiNH2-MH (M = Na,K) Eutectic Mixture

The hunt for a cleaner energy carrier leads us to consider a source that produces no toxic byproducts. One of the targeted alternatives in this approach is hydrogen energy, which, unfortunately, suffers from a lack of efficient storage media. Solid-state hydrogen absorption systems, such as lithium amide (LiNH₂) systems, may store up to 6.5 weight percent hydrogen. However, the temperature of hydrogenation and dehydrogenation is too high for practical use. Various molar ratios of LiNH₂ with sodium hydride (NaH) and potassium hydride (KH) have been explored in this paper. The temperature of hydrogenation for LiNH₂ combined with KH and NaH was found to be substantially lower than the temperature of individual LiNH₂. This lower temperature operation of both LiNH₂-NaH and LiNH₂-KH systems was investigated in depth, and the eutectic melting phenomenon was observed. Systematic thermal studies of this amide-hydride system in different compositions were carried out, which enabled the plotting of a pseudo-binary phase diagram. The occurrence of eutectic interaction increased atomic mobility, which resulted in the kinetic modification followed by an increase in the reactivity of two materials. For these eutectic compositions, i.e., 0.15LiNH₂-0.85NaH and 0.25LiNH₂-0.75KH, the lowest melting temperature was found to be 307 °C and 235 °C, respectively. Morphological studies were used to investigate and present the detailed mechanism linked with this phenomenon.     

An Encryption Algorithm for Region of Interest in Medical DICOM Based on One-Dimensional eλ-cos-cot Map

Today, with the rapid development of the Internet, improving image security becomes more and more important. To improve image encryption efficiency, a novel region of interest (ROI) encryption algorithm based on a chaotic system was proposed. First, a new 1D eλ-cos-cot (1D-ECC) with better chaotic performance than the traditional chaotic system is proposed. Second, the chaotic system is used to generate a plaintext-relate keystream based on the label information of a medical image DICOM (Digital Imaging and Communications in Medicine) file, the medical image is segmented using an adaptive threshold, and the segmented region of interest is encrypted. The encryption process is divided into two stages: scrambling and diffusion. In the scrambling stage, helical scanning and index scrambling are combined to scramble. In the diffusion stage, two-dimensional bi-directional diffusion is adopted, that is, the image is bi-directionally diffused row by column to make image security better. The algorithm offers good encryption speed and security performance, according to simulation results and security analysis.     

导电聚苯胺线膜修饰ZnO纳米棒阵列的可控制备及其紫外探测性能

基于p-n结的光生伏特效应可构筑性能优异的UV探测器,本文采用水热法可控制备竖直排列的氧化锌纳米棒阵列(n型ZnO-NRs),利用原位聚合法在ZnO-NRs表面上修饰p型聚苯胺线膜(PANI-NWs),再组装成ZnO-NRs与ZnO-NRs/PANI-NWs紫外探测器.通过扫描电镜(SEM)、X射线衍射仪(XRD)、紫...     

Dielectric Properties Investigation of Metal–Insulator–Metal (MIM) Capacitors

This study presents the construction and dielectric properties investigation of atomic-layer-deposition Al₂O₃/TiO₂/HfO₂ dielectric-film-based metal–insulator–metal (MIM) capacitors. The influence of the dielectric layer material and thickness on the performance of MIM capacitors are also systematically investigated. The morphology and surface roughness of dielectric films for different materials and thicknesses are analyzed via atomic force microscopy (AFM). Among them, the 25 nm Al₂O₃-based dielectric capacitor exhibits superior comprehensive electrical performance, including a high capacitance density of 7.89 fF·µm⁻², desirable breakdown voltage and leakage current of about 12 V and 1.4 × 10⁻¹⁰ A·cm⁻², and quadratic voltage coefficient of 303.6 ppm·V⁻². Simultaneously, the fabricated capacitor indicates desirable stability in terms of frequency and bias voltage (at 1 MHz), with the corresponding slight capacitance density variation of about 0.52 fF·µm⁻² and 0.25 fF·µm⁻². Furthermore, the mechanism of the variation in capacitance density and leakage current might be attributed to the Poole–Frenkel emission and charge-trapping effect of the high-k materials. All these results indicate potential applications in integrated passive devices.     

基于串行最小频移键控的8进制调制的研究

提出了一种新型的基于串行结构的最小频移键控调制技术,产生了相位连续,频谱宽度窄,每码元时间有两次π/2相移,类似于传统最小频移键控调制信号,给出了该调制方案的理论推导,并将其应用于8进制的多维多阶调制系统中。理论和仿真分析了不同的8进制调制方案在频谱特性,残留色散容限,自相位调制容限的不同,还分析了其受到系统滤波带宽的影响。最后仿真实现了通过350km的色散完全补偿的光纤120Gb/s的数据传输。     

Dislocation driven chromium precipitation in Fe-9Cr binary alloy: a positron lifetime study

The influence of initial heat treatment on anomalous Cr precipitation within high temperature solubility region of the Fe–9Cr alloy has been investigated using positron lifetime studies. Air-quenched samples with pre-existing dislocations exhibited a distinct annealing stage in positron lifetime between 800 and 1100?K corresponding to Cr-precipitation. During this stage, Transmission Electron Microscopy showed fine precipitates of average size 4 nm, dispersed throughout the sample and from Energy-dispersive X-ray spectroscopy (EDS) analysis they are found to be Cr-enriched. The presence of dislocations is found to be responsible for Cr precipitation.     

Synthesis of a benzoxazine with precisely two phenolic OH linkages and the properties of its high‐performance copolymers

A phenolic OH‐containing benzoxazine ( F‐ap ), which cannot be directly synthesized from the condensation of bisphenol F, aminophenol, and formaldehyde by traditional procedures, has been successfully prepared in our alternative synthetic approach. F‐ap was prepared by three steps including (a) condensation of 4‐aminophenol and 5,5'‐methylenebis(2‐hydroxybenzaldehyde) (1) , (b) reduction of the resulting imine linkage by sodium borohydride, and (c) ring closure condensation by formaldehyde. The key starting material, (1) , was prepared from 2‐hydroxybenzaldehyde and s‐trioxane in the presence of sulfuric acid. F‐ap is structurally similar to bis(3,4‐dihydro‐2H‐3‐phenyl‐1,3‐benzoxazinyl)methane ( F‐a, a commercial benzoxazine based on bisphenol F/aniline/formaldehyde) except for two phenolic OHs. The phenolic OHs can provide reaction sites with epoxy and 1,1'‐(methylenedi‐p‐phenylene)bismaleimide (BMI). The structure–property relationships between the thermosets of F‐ap /epoxy, F‐a /epoxy, F‐ap /BMI, and F‐a /BMI were discussed. Experimental data showed that thermosets based on F‐ap /epoxy and F‐ap /BMI provided much better thermal properties than those based on F‐a /epoxy and F‐a /BMI. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2686–2694     

高效液相色谱法同时测定生物质乳酸发酵液中有机酸及糖类化合物

建立了高效液相色谱(HPLC)同时测定生物质乳酸发酵液中有机酸及糖类的分析方法。使用Bio-Rad Aminex HPX-87H色谱柱,以5 mmol/L的H2SO4为流动相,在柱温55 ℃,流速0.6 mL/min条件下,采用示差折光检测器进行检测。结果表明,该方法可在17 min内实现发酵液中各种有机酸和糖类化合物等的完全分离与定量,6种有机酸和3种糖类化合物在0.15～5.19 g/L范围内的线性关系良好,回归方程的线性相关系数在0.9998以上。将该法用于米根霉发酵液的检测,两个水平的加标回收率为96.91%～103.11%,相对标准偏差(n=6)为0.81%～4.61%。该法适用于微生物发酵液中多种有机酸和糖类的快速、高效分离和定量测定。     

Liquid Chromatograph Detector for Trace Analysis of Non-Volatile N-Nitroso Compounds

Abstract

A Thermal Energy Analyzer has been interfaced to a high performance liquid chromatograph. The hplc-TEA system can be used for analysis of nanogram amounts of N-nitroso compounds.     

反相高效液相色谱法制备银杏叶中聚戊烯醇同系物单体

利用制备高效液相色谱法从银杏叶中分离制备了聚戊烯醇同系物单体。在HiQ sil C18柱上,以异丙醇-甲醇-正己烷-水(体积比为50∶25∶15∶4)为流动相,流速10 mL/min,采用等度洗脱方式,制备了8种化合物,经紫外光谱、红外光谱及质谱分析,确认它们分别为C70,C75,C80,C85,C90,C95,C100和C105聚戊烯醇,其中主要成分为C85及C90聚戊烯醇。高效液相色谱分析表明,制备的C75C105聚戊烯醇化合物的纯度均在96%(质量分数)以上。在该色谱条件下,各色谱峰达到了基线分离,