基于CPLD工作模式可调的线阵CCD驱动电路设计

针对传统驱动电路一旦做出修改,则需对硬件或程序进行改变的缺点,以型号为TCD1707D的线阵CCD为例,介绍了一种工作模式可调的驱动方法.该方法是利用复杂可编程逻辑器件和控制外端结合,通过分别设置内外触发来实现的.在外触发模式下,利用外触发脉冲,可由用户控制CCD的曝光和信号输出时间;内触发时,可以调节CCD的积分时间和驱动频率.为提高信号输出质量,针对EMC问题给出了线阵CCD的外围驱动电路.实验结果表明,该方法调试方便、电路结构简单、集成度较高、输出信号可靠稳定、受干扰小,可配合多种用户需要,对高速精确测量及线阵推扫模式具有一定参考价值.     

Helium trapping at dislocations,precipitates and grain boundaries

Helium bubble formation was observed in austenitic stainless steels by transmission electron microscopy following implantation of 30 to 1000 appm helium at room temperature and annealing at 700 to 800°C. Helium bubble distributions at dislocations and at various grain boundaries and precipitates were studied. It was found that interfacial dislocations play a dominant role in bubble nucleation at grain and interphase boundaries but not at Tic-matrix interfaces. Particularly high trapping of helium was observed at Tic precipitate-matrix interfaces which is attributed to an inhomogeneous ripening mechanism.     

茶叶中咖啡因的提取实验装置的改进与探索

"茶叶中咖啡因的提取"是有机化学实验的一个经典实验,本文对该实验所用的原索氏提取器进行改进,得到内通气集热式索氏提取器并用于实验教学。通过对照实验,对改进索氏提取器和原索氏提取器的提取效果进行比较。结果表明,改进装置具有原装置的功能和特点,且提取时间更短、提取温度和提取率更高,可在高校推广使用。     

Migration of perfluorinated compounds from paperbag to Tenax® and lyophilised milk at different temperatures

ABSTRACT

Migration tests of perfluoroalkyl substances (PFASs) from a grease-proof paperbag used for packaging of pet food have been carried out. No migration of perfluorocaboxylic acids (PFCAs), from PFBA to PFTeDA, to the simulant Tenax® was found after 10 days at 40°C. However, the increase of temperature in the range 80–160°C gave rise to the migration of the PFCAs. Finally, the migration to real foods such as lyophilised whole and low-fat milk samples at 80 and 120°C was studied. The results indicate that the migration percentages of the PFCASs into food samples are much higher than those obtained into Tenax®.     

Zn-Organic Batteries for the Semi-Hydrogenation of Biomass Aldehyde Derivatives and Concurrently Enhanced Power Output

Electricity generation and chemical productions are both critically important for the sustainable development of modern civilization. Here, a novel bifunctional Zn-organic battery has been established for the concurrent enhanced electricity output and semi-hydrogenations of a series of biomass aldehyderivatives, for the high value-added chemical syntheses. Among them, the typical Zn-furfural (FF) battery equipped with Cu foil-supported edge-enriched Cu nanosheets as cathodic electrocatalyst (Cu NS/Cu foil), provides a maximum current density and power density of 14.6 mA cm⁻² and 2.00 mW cm⁻², respectively, and in the meantime, produces high value product, furfural alcohol (FAL). The Cu NS/Cu foil catalyst exhibits excellent electrocatalytic performance of ≈93.5 % conversion ratio and ≈93.1 % selectivity for FF semi-hydrogenation at a low potential of -1.1 V vs. Ag/AgCl by using H₂O as H source, and shows impressive performance for various biomass aldehyderivatives semi-hydrogenation.     

Two-Dimensional Conjugated Metal-Organic Frameworks with Large Pore Apertures and High Surface Areas for NO2 Selective Chemiresistive Sensing

The emergence of two-dimensional conjugated metal–organic frameworks (2D c-MOFs) with pronounced electrical properties (e.g., high conductivity) has provided a novel platform for efficient energy storage, sensing, and electrocatalysis. Nevertheless, the limited availability of suitable ligands restricts the number of available types of 2D c-MOFs, especially those with large pore apertures and high surface areas are rare. Herein, we develop two new 2D c-MOFs (HIOTP-M, M=Ni, Cu) employing a large p-π conjugated ligand of hexaamino-triphenyleno[2,3-b:6,7-b′:10,11-b′′]tris[1,4]benzodioxin (HAOTP). Among the reported 2D c-MOFs, HIOTP-Ni exhibits the largest pore size of 3.3 nm and one of the highest surface areas (up to 1300 m² g⁻¹). As an exemplary application, HIOTP-Ni has been used as a chemiresistive sensing material and displays high selective response (405 %) and a rapid response (1.69 min) towards 10 ppm NO₂ gas. This work demonstrates significant correlation linking the pore aperture of 2D c-MOFs to their sensing performance.     

Synthesis of 14-epi-19-nor-22-oxa-1α,25-dihydroxyvitamin D3

The synthesis of 14-epi-19-nor-22-oxa-1α,25(OH)2D3 5 was started from diol 8 via Fall's method, oxidation, epimerization, protection, coupling with the 19-nor-A-ring 7, and then deprotection of the hydroxyl functions.     

Thermal and mechanical properties of particulate fillers filled epoxy composites for electronic packaging application

Epoxy composites containing particulate fillers‐fused silica, glass powder, and mineral silica were investigated to be used as substrate materials in electronic packaging application. The content of fillers were varied between 0 and 40 vol%. The effects of the fillers on the thermal properties—thermal stability, thermal expansion and dynamic mechanical properties of the epoxy composites were studied, and it was found that fused silica, glass powder, and mineral silica increase the thermal stability and dynamic thermal mechanical properties and reduce the coefficient of thermal expansion (CTE). The lowest CTE value was observed at a fused silica content of 40 vol% for the epoxy composites, which was traced to the effect of its nature of low intrinsic CTE value of the fillers. The mechanical properties of the epoxy composites were determined in both flexural and single‐edge notch (SEN‐T) fracture toughness properties. Highest flexural strength, stiffness, and toughness values were observed at fillers content of 40 vol% for all the filled epoxy composites. Scanning electron microscopy (SEM) micrograph showed poor filler–matrix interaction in glass powder filled epoxy composites at 40 vol%. Copyright © 2007 John Wiley & Sons, Ltd.     

Fabric phase sorptive extraction: An innovative sample preparation approach applied to the analysis of specific migration from food packaging

Additives added to food packaging materials can migrate to food in contact with them during storage and shelf life. A novel simple, fast and sensitive analyte extraction method based on fabric phase sorptive extraction (FPSE), followed by analysis using ultra-high performance liquid chromatography and mass spectrometry detection (UPLC-MS) was applied to the analysis of 18 common non-volatile plastic additives. Three FPSE media coated with different sol-gel sorbents characterized with different polarities including sol-gel poly(dimethylsiloxane), sol-gel poly(ethylene glycol) and sol-gel poly(tetrahydrofuran) were studied. All three FPSE media showed very satisfactory results. In general, compounds with low logP values seemed to have higher enrichment factors (EFs), especially with poly(tetrahydrofuran) and poly(ethylene glycol) media. For compounds with high logP values, the use of sol-gel poly(dimethylsiloxane) improved the enrichment capacity. Sample preparation time was optimized at 20 min for sample extraction and 10 min for solvent desorption. Acetonitrile was selected as desorption solvent since recoveries were over 70% for 13 out of 18 selected compounds in all FPSE media. The best extraction recovery values were obtained when compounds were dissolved in aqueous acetic acid solution (3%), where 17 out of 18 compounds showed improvement in their signal intensity after FPSE extraction and 10 obtained enrichment factors above 3 for all the tested FPSE media. When FPSE extracts were concentrated under nitrogen, 11 out of 18 compounds reached EFs values above 100.     

Evaluation of the migration of UV-ink photoinitiators from polyethylene food packaging by supercritical fluid chromatography combined with photodiode array detector and tandem mass spectrometry

UV-ink photoinitiators (PIs), which are used to initiate polymerization reaction for the curing of inks and lacquers, have become a kind of contaminant residues in printing plastic food packaging. The residual PIs in packaging may pose a potential threat to customers. In this work, migration behaviors of 13 PIs from a polyethylene (PE) packaging to food simulants according to regulation EU No 10/2011 were studied by supercritical fluid chromatography combined with photodiode array detector and tandem mass spectrometry (SFC-PDA-MS/MS). The method simultaneously analyzed 13 PIs within 4.5 min and was sensitively with low limits of detection of 0.02–2.16 μg/L, which could meet high throughput analysis for control the quality of food packaging. The migration results revealed that Irgacure 819, Darocure 1173 and TPO, which had low migration rates, should be preferably selected by plastic food packaging manufacture for food safety.