Low temperature crystallographic data on Kevlar 49 fibres

Using X-ray diffraction data, the behaviour of Kevlar 49 fibres at low temperatures, up to –100°C, has been analysed. During cooling, the basal plane of the monoclinic unit cell shrinks whereas the c- (unique, chain axis) length is not significantly affected. In contrast, in the return heating cycle to ambient temperature, the basal plane expands and contraction occurs along the chain direction. The unit cell registers a reduction in volume in both the cooling and heating cycles. Conspicuously, after a cycle of cooling and heating, the unit cell does not return to its initial volume.     

Protein binding study of isoflavone, perillyl alcohol and S-ibuprofen by high-performance frontal analysis

High-performance frontal analysis (HPFA) was used for a protein binding study of isoflavones (daidzein, genistin, and genistein), enantiomers of perillyl alcohol and S-ibuprofen to human serum albumin (HSA). The analyses were performed on a Develosil and Inertsil 100-Diol-5 column (10 cm×4.6mm). Sodium phosphate solution (pH 7.4, ionic strength 0.17) was used as the mobile phase at a flow rate of 1 ml/min. To ensure the drug to be eluted as a trapezoidal peak with a plateau, injection volumes were each fixed up the zonal profile with an evident plateau appears. The unbound drug concentration was determined from a plateau height of the plateau region after that experimental data were fitted by Scatchard equation. The binding constants (K) and total binding affinities (nK) of drugs to HSA were calculated, respectively.     

Experimental study of circularly polarised microstrip antennas loaded with superstrate

The loading effects of the superstrate with various thickness on the circular polarisation (CP) performances of a cross-slot-coupled microstrip antenna are first investigated. Then, for improving the shifted centre frequency, the bad impedance matching, and the increased axial ratio, which are due to the superstrate effects, the key dimensions of the loaded antenna are adjusted to regain or even enhance the original unloaded CP performances. From the obtained experimental results, it is found that the CP bandwidth of the loaded antenna can be increased when the thickness of the superstrate is properly selected.     

Characteristics of gas-liquid chromatography

The effects of sample size, liquid loading, particle size, column length, and column temperature on retention volumes were studied and separation factor, column efficiency, partition coefficient, and heat of solution were also obtained by gas-liquid chromatography. The feed materials were chosen by similar boiling points as diethylether, dimethoxymethane and dichloromethane. The relations between retention volume and above mentioned various variables were obtained. Separation factor was more affected by column temperature than other variables, and decreased with the temperature. HETP increased almost linearly with sample size. From the exponential relationship between partition coefficient and column temperature heat of solution of each material was calculated.     

Enhanced extraction of isoflavones from Korean soybean by ultrasonic wave

The amounts of isoflavones extracted from Korean soybean by various ultrasonic waves were compared using 60% aqueous ethanol solution. The effect on extraction yield of variations in solvent composition, temperature, and extraction time was investigated. The experimental results confirmed that ultrasonic waves are a desirable method to extract isoflavones from Korean soybean. The highest yield of aglycone isoflavones was obtained by ultrasonic waves with a frequency of 20 KHz and an extraction time of 10 min, which produced yields of glycoside and aglycone isoflavones three-fold greater than those by dipping method.     

亲子餐厅成蓝海 只有满足一家人需求的才能成功

正你有没有发现,很多大型购物中心正在增加儿童业态的比重?在零售逐渐失去吸引力的时候,购物中心开始惦记着这一新生代,甚至开辟出超过15%-25%的经营面积专供儿童业态。拿北京来举例,北京最著名的王府井商圈,这两年逐渐调整成了亲子友善的消费场景。拥有200多年历史的英国哈姆雷斯玩具店之前在王府井百货大楼开设了全球最大旗舰店;apm王府井店引入了美国品牌Toys"R"Us(玩具反斗城);新中国儿童用品商店也调整了商场的总体布局,     

Slot-coupled microstrip antenna for broadband circular polarisation

A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%.     

SO2-removal using ammonia solution in a packed column

The effect of variables on efficiency of SO₂ removal from a simulated waste gas by use of ammonia solution was studied. The variables were gas, feed solution and recirculation flow rate, SO₂ concentration in the gas phase, NH₃ concentration in the ammonia solution, and pH in scrubber effluent solutions. The scrubber was 3“ — OD methyl metacrylate column packed with 1 •4” — plastic Rasching rings in 90 cm packed height. Solution analysis was performed by Palmrose method and pH meter. The following empirical equations were obtained by regression analysis; EFF = 33.52 G^0.0552 F^0.118 R^0.772 EFF = 64.10 S^0.143 N^0.0153 k_G = 3.51 x 10^-6 G^1.160 L_0.647     

Reconfigurable microstrip antenna with pattern and polarisation diversities

A microstrip antenna with the functions of switchable pattern and polarisation is presented. The antenna is composed of a square-ring radiating patch and four shorting walls. The shorting walls are connected to each edge of the square-ring patch through one pin diode. By controlling the states of the pin diodes, the square-ring microstrip antenna can radiate two complementary patterns (conical and broadside); moreover, dual orthogonal linear polarisations are provided for the broadside radiation. These diversity functions are operated at the same frequency band. An antenna prototype has been implemented and the results obtained are given     

Reconfigurable microstrip antenna with polarisation diversity and frequency agility

A circularly-polarised (CP) microstrip antenna with polarisation and frequency diversities is presented. The antenna has a square radiating patch and is excited through the coupling of a cross-slot with unequal lengths. Two diodes are used to reconfigure the radiating patch, and by controlling the states of the diodes, the polarisation sense of the antenna can be switched between left-hand and right-hand circular polarisation. Moreover, the two CP modes are operated at different frequencies. An antenna prototype is implemented and the obtained results are shown.