Analysis of the Mechanism of Counter-current Spray Drying

Results of experimental investigations of the effect of drying and atomization parameters on counter-current spray drying are discussed. Based on 96 experimental tests, the local and global distributions of velocity, temperature, drying air humidity and moisture content of material dried in the drying tower were determined. Analysis of the results showed that the process of agglomeration during counter-current spray drying depended mainly on air temperature in the atomization zone.     

Simultaneous determination of seven lignans in Justicia procumbens by high performance liquid chromatography–photodiode array detection using relative response factors

A simple and sensitive HPLC coupled with photodiode array (HPLC–PDA) method was developed for simultaneous determination of seven lignans in Justicia procumbens using relative response factors (RRFs). The chromatographic separation was performed on a Shiseido Capcell Pak C₁₈ column (250 × 4.6 mm id, 5 μm), a gradient elution of acetonitrile/water, and a photodiode array detector. The column temperature was maintained at 35°C and the detection wavelength was set at 256 nm. Chinensinaphthol methyl ether was selected as the reference compound for calculating the relative response factors of the lignans. It has shown that the RRFs for lignans are quite similar at 256 nm of detection under different analytical conditions (different columns and HPLC instruments). Using RRFs, not every lignan is needed as a reference standard, making the method ideal for rapid, routine analysis, especially for those laboratories where lignans standards are not readily available. An economic and practicable HPLC method using RRFs was established for the determination of seven lignans in J. procumbens. This method not only can determine multiple indexes in traditional Chinese medicines (TCMs) simultaneously, but also resolve the problem of lacking of chemical standards. It will be a good quality evaluation method and pattern for TCMs.     

柔性PDA薄膜阵列用于双模光学检测VOC标志物气体

本研究以亲油性的双面胶作为基底,利用滴涂二乙炔单体结合紫外光聚合来制备均匀的聚二乙炔(PDA)薄膜,通过荧光和颜色两种信号变化模式(即"双模光学检测")研究了PDA薄膜对VOC气体的响应性,发现制备的PDA薄膜在2 min内就可以实现明显的荧光和颜色变化,有效解决了目前PDA薄膜在VOC气体检测方面存在响应速度慢、薄膜均一性差等问题.此外,为解决单一PDA薄膜的交叉响应性问题,本研究制备了四种不同的基于双面胶基底的PDA薄膜,并将制备的4种PDA薄膜集成到一片PDMS薄膜基底上来构建柔性的传感阵列,利用阵列的颜色变化结合模式识别技术,实现了对8种VOC气体的快速、灵敏区分.进一步将制备的PDA薄膜阵列用于健康人、模拟糖尿病及肾病患者呼出气体中VOC标志物的辨别和分析研究,发现可以将三类人的呼出气体清晰地区分,说明了该阵列在呼气疾病诊断中的应用前景.与目前报道的PDA薄膜阵列相比,本研究中基于双面胶基底的PDA薄膜阵列具有气体响应速度快、灵敏性高、柔韧性好、制备工艺简单、成本低、易于大规模制备等优点,有望用于实VOC气体检测研究中.     

Structural properties and electrical characteristics of high-k Dy2O3 gate dielectrics

This paper describes the structural properties and electrical characteristics of thin Dy₂O₃ dielectrics deposited on silicon substrates by means of reactive sputtering. The structural and morphological features of these films after postdeposition annealing were studied by X-ray diffraction and X-ray photoelectron spectroscopy. It is found that Dy₂O₃ dielectrics annealed at 700 °C exhibit a thinner capacitance equivalent thickness and better electrical properties, including the interface trap density and the hysteresis in the capacitance-voltage curves. Under constant current stress, the Weibull slope of the charge-to-breakdown of the 700 °C-annealed films is about 1.6. These results are attributed to the formation of well-crystallized Dy₂O₃ structure and the reduction of the interfacial SiO₂ layer.     

基于二极管阵列PDA的紫外-可见差分吸收光谱(DOAS)系统的研究

介绍了一种自行研制的长程差分光学吸收光谱(DOAS)系统,该系统采用光电二极管阵列(PDA)作为光谱检测器,代替结构较为复杂的光电倍增管(PMT)加扫描圆盘的SD检测器,并对该系统检测器的偏置、暗电流、噪声、线性以及光谱仪的分辨率、光谱范围等性能进行了测试,同时对SO₂,NO₂等大气污染物进行了外场的测定,确定出相应光程下该系统测量SO₂,NO₂的最低检测限。     

Creation and application of psychoactive designer drugs data library using liquid chromatography with photodiode array spectrophotometry detector and gas chromatography-mass spectrometry

In order to quickly confirm a potentially hazardous psychoactive designer drug (a compound in which part of the molecular structure of a stimulant or narcotic has been modified), we created a psychoactive drugs data library by performing analysis using liquid chromatography with photodiode array spectrophotometry (LC/PDA) and gas chromatography-mass spectrometry (GC/MS). The data in this library consist of the LC capacity factor (k′) ratios in relation to the internal standard, the ultraviolet (UV) spectra and the MS spectra of 104 compounds. By performing a comparative study of the data in this report with the analytical data for commercial and illegal drug products, it is possible to quickly identify the psychoactive designer drugs in 205 purchased products by using the library. Further, it is possible to analogize the structure of drugs for which there is no matching data in the library using similar data.Furthermore, when structural isomers of controlled substances have detected from the presented library, similarity of their biological effects on human will be predicted, thus leading to regulate their public circulation. Examples of these types of isomers include, for instance, the narcotic 3,4,5-trimethoxyamphetamine (TMA) and its positional isomers 2,4,5-trimethoxyamphetamine (TMA-2) and 2,4,6-trimethoxyamphetamine (TMA-6), or the narcotic 1-(3-chlorophenyl)piperazine (3CPP) and its isomers 1-(o-chlorophenyl)piperazine (2CPP) and 1-(p-chlorophenyl)piperazine (4CPP). Differentiation of these compounds is necessary in regulating them, and we report here the results of a study of a method to confirm these compounds using the present library.     

分级进风燃烧室内高温气固两相流动的PDA测量

本文建立了分级进风燃烧室高温气固两相流动的实验装置。利用三维激光粒子动态分析仪(PDA),测量了燃烧室内有气相燃烧的高温气固流动的两相瞬时速度场。得到了平均轴向与切向速度、轴向与切向脉动速度均方根值和轴向-切向脉动速度关联量的分布。     

Correlation of Plasma Sprayed Coating Deposition Efficiency with Volume Flux Measurements by Phase Doppler Anemometry (PDA)

The use of phase-Doppler anemometry (PDA) to characterize the detail in-flight plasma sprayed particle behavior has been demonstrated previously [Ma et al. Plasma Chem Plasma Process 24(1):85; 25(1):56] The present articles shows further that a direct relationship may exist between the PDA measured particle volume flux and the coating microstructure and deposition efficiency (DE). In the situation when the precise particle temperature information is not available, the PDA measured particle volume flux may provide an alternative to predict quantitatively the variation of the coating microstructure and the DE. By monitoring the in-flight particle volume flux variations, instead of the particle velocity, size and temperature individually and simultaneously, the optimal settings of the plasma spraying parameters may also be determined conveniently. However, it is noted that the effective applications of such approach depend largely on the particle surface morphology and the pre-determination of the particle size range.     

Feasibility Exploration of Laser‐based Techniques for Characterization of a Flashing Jet

Two‐phase flows hold an interest in many areas of science and engineering. In the safety field, one such topic is the accidental release of flammable and toxic pressure‐liquefied gases. In case of such a release, a flashing vapor explosion takes place resulting in a very dense two‐phase cloud. If the released substance is flammable, this cloud can be combustible and can lead to deflagration or detonation. For understanding the source processes of flashing and risk assessment, data related to cloud characteristics (i.e. droplet size, velocity etc.) is needed especially in the near region of the release. Due to the non‐equilibrium nature of the near field regions accurate data measurement is not possible with intrusive techniques. Therefore, laser‐based optical techniques (like Particle Image Velocimetry (PIV), Particle Tracking Velocimetry and Sizing (PTVS), Phase Doppler Anemometry (PDA) etc.) present the only possibility to obtain information for particle diameter and velocity evolution in this harsh environment.