Synthesis of magnetite nanoparticles by surfactant-free electrochemical method in an aqueous system

A simple surfactant-free electrochemical method is proposed for the preparation of magnetite nanoparticles using iron as the anode and plain water as the electrolyte. This study observed the effects of certain parameters on the formation of magnetite nanoparticles and their mechanism in the system, including the role of OH^? ions, the distance between electrodes and current density. We found that OH^? ions play an important role in the formation of magnetite nanoparticles. Particle size can be controlled by adjusting the current density and the distance between electrodes. Particle size increases by increasing the current density and by decreasing the distance between electrodes. Particle formation cannot be favored when the distance between electrodes is larger than a critical value. The magnetite nanoparticles produced by this method are nearly spherical with a mean size ranging from 10 to 30 nm depending on the experimental conditions. They exhibit ferromagnetic properties with a coercivity ranging from 140 to 295 Oe and a saturation magnetization ranging from 60 to 70 emu g^?1, which is lower than that of the corresponding bulk Fe₃O₄ (92 emu g^?1). This simple method appears to be promising as a synthetic route to producing magnetite nanoparticles.     

The effect of cognitive and affective aspects on usability

Studies on customer’s needs, desires and preferences have become highly important in the product design and development process. One consideration in usability is the cognitive aspect, which is related to the accommodation and evaluation of human cognitive capabilities, limitations and tendencies. In addition to the cognitive aspect, a recent study has shown that the affective aspect has been considered in the evaluation of product usability. Thus, both cognitive and affective aspects are deemed to be important for product design and the development process. Inherently, both aspects deliver complete human and product interaction and experience. However, studies that consider the affective process as a complement to the cognitive process for usability are relatively rare. To address this gap, this study discusses how an integrative framework of the cognitive and affective aspects can be applied to a product for usability assessment via empirical studies on e-commerce and e-learning platforms. The sample involved 230 respondents, using purposive sampling. The result shows that both cognitive and affective aspects have a significant effect, although with different weights. The affective aspect has been shown to improve product usability and user’s acceptance.     

IBM—PC微机化工数据库的开发

微机化工数据库由数据检索,物性估算,气液平衡计算,数据回归四系统组成。该系统有数据可靠,操作简便,运行效率高以及兼备中英文操作语种等特点,并附带文献库。     

Influences of solution chemistry and polymeric natural organic matter on the removal of aquatic pharmaceutical residuals by nanofiltration

This study demonstrates the removal efficiency and the permeate flux behavior during cross-flow nanofiltration (NF) of aqueous solutions of five pharmaceutically active compounds (PhACs). Cephalexin, tetracycline, acetaminophen, indomethacin and amoxicillin were used as models of PhACs, and alginate was selected as model of natural organic matter (NOM). Two commercial composite NF membranes (SR2 and SR3) with different characteristics were used. The highest rejection was observed for tetracycline, i.e., 75-95% for membrane SR 2 and 95-100% for membrane SR 3, while the rejection was least for acetaminophen (32-36% for SR2 and 52-59% for SR3). As the pH of acetaminophen solution was increased (from 6 to 9) the rejection would increase. Changes of ionic content (from 10 to 20 mM) lead to increase (from 89 to 93% for SR 3) or decrease (from 100 to 91% for SR2) of cephalexin rejection depending on the membrane used. The permeate flux would decrease with decreasing the pH solution and increasing ionic strength. The addition of alginate in the feed stream decreased the permeate flux, with lower reduction for SR3, and increased the PhAC rejection except for acetaminophen and amoxicillin. Both size and Donnan exclusions seemed to occur, and the effect of Donnan exclusion was more pronounced for the NF membrane having larger effective pore size (SR2).     

Detecting moving objects from a video taken by a moving camera using sequential inference of background images

This paper proposes a method of detecting moving objects using sequential inference of the background in a video taken with a moving camera. In the video taken using a moving camera, all positions of pixels change every frame. The positions of the background pixels in the image frame T are not the same as the positions of the background pixels in the image frame T + 1. 2D projective transform can be used to find changes in the pixel position every frame. Bilinear interpolation with four nearest pixels around the pixel in image frame T which corresponds to a pixel in the image frame T+1 can be used for creating a background model at T + 1. Having obtained the background model, a pixel in image frame T + 1 can be determined if it is a background pixel or a foreground pixel. The detection results of the proposed method are compared with the ground truth to determine the effectiveness of the proposed method.     

Hygrothermal effects of glass fiber reinforced unsaturated polyester resin composites aged in steady and fluctuating conditions

This paper presents the water uptake and its effect on the tensile properties and the translaminar fracture toughness of glass fiber reinforced unsaturated polyester composites (GFRUPs) aged in distilled and saltwater at a temperature of 50 °C, in steady and fluctuating conditions. In both conditions, the GFRUPs aged in distilled water absorbed more water than in saltwater. The tensile strength of GFRUP tends to decrease with the immersion time in both aging media, but the decrease of tensile strength in saltwater is worse than that in distilled water. In steady condition, the translaminar fracture toughness increases after 7 days immersion and then tends to decrease beyond that immersion time. While in fluctuating condition, the translaminar fracture toughness increases until 15 days immersion and then gradually decreases up to 30 days immersion. Overall, the degradation of mechanical properties in the fluctuating condition is lower than in the steady condition.     

An incorporative statistic and neural approach for crop yield modelling and forecasting

An incorporative framework is proposed in this study for crop yield modelling and forecasting. It is a complementary approach to traditional time series analysis on modelling and forecasting by treating crop yield and associated factors as a non-temporal collection. Statistics are used to identify the highly related factor(s) among many associates to crop yield and then play a key role in data cleaning and a supporting role in data expansion, if necessary, for neural network training and testing. Wheat yield and associated plantation area, rainfall and temperature in Queensland of Australia over 100 years are used to test this incorporative approach. The results show that well-trained multilayer perceptron models can simulate the wheat production through given plantation areas with a mean absolute error (MAE) of ~2%, whereas the third-order polynomial correlation returns an MAE of ~20%. However, statistical analysis plays a key role in identifying the most related factor, detecting outliers, determining the general trend of wheat yield with respect to plantation area and supporting data expansion for neural network training and testing. The combination of these two methods provides both meaningful qualitative and accurate quantitative data analysis and forecasting. This incorporative approach can also be useful in data modelling and forecasting in other applications due to its generic nature.     

一类最优的零相关区非周期互补序列集构造法

该文基于正交序列集,研究了一类新的零相关区(ZCZ)非周期互补序列(ZACS)集构造方法,所得到的序列集参数达到最优,且在满足Z|N的条件下零相关区长度可以灵活选择.该方法所构造的序列具有理想的自相关性能和组内互补特性.通过调整参数q,可得到多个不同的序列集.同时,基于多电平完备序列,给出了一类高斯整数正交序列集的构造方法,得到的高斯整数正交序列集可以用于非周期互补序列集的构造.所提方法构造的零相关区非周期互补序列集用于多载波码分多址系统中可以降低多径干扰、多址干扰,也可以作为训练序列用于多输入多输出信道估计中.     

Morphology,Structure, and Mechanical Properties of Natural Cellulose Fiber from Mendong Grass (Fimbristylis globulosa)

This study was to investigate the morphology, structure, and chemical properties of the Mendong fibers extracted from Mendong grass (Fimbristylis globulosa) in the form of raw and treated fiber by alkali-included chemical content and functional group and to evaluate the strength and properties of Mendong fibers compared with other natural fibers. These studies explore the chemical properties of the fiber including fiber composition and functional group by FTIR, mechanical properties of fiber, and the structural and morphological analysis of the fiber using SEM and XRD. The results showed that the chemical contents of Mendong fibers were 72.14% cellulose, 20.2% hemicellulose, 3.44% lignin, 4.2% extractive, and moisture of 4.2%–5.2%. Mechanical properties of the fiber were a strong character with tensile strength of 452 MPa, and modulus of 17 GPa. The structural properties of Mendong fiber such as crystallinity, crystalline index, microfibril angle, and crystalline size were 70.17% and 58.6%, 22.9°, and 14.3 nm, respectively. This fiber has competitive advantages compared with other natural fibers and can be developed further as a potential reinforcement of polymer matrix composites.