Compact Modules for Wireless Communication Systems in the E-Band (71–76 GHz)

The millimeter-wave spectrum above 70 GHz provides a cost-effective solution to increase the wireless communications data rates by increasing the carrier wave frequencies. We report on the development of two key components of a wireless transmission system, a high-speed photodiode (HS-PD) and a Schottky Barrier Diode (SBD). Both components operate uncooled, a key issue in the development of compact modules. On the transmitter side, an improved design of the HS-PD allows it to deliver an output RF power exceeding 0 dBm (1 mW). On the receiver side, we present the design process and achieved results on the development of a compact direct envelope detection receiver based on a quasi-optical SDB module. Different resonant (meander dipole) and broadband (Log-Spiral and Log-Periodic) planar antenna solutions are designed, matching the antenna and Schottky diode impedances at high frequency. Impedance matching at baseband is also provided by means of an impedance transition to a 50 Ohm output. From this comparison, we demonstrate the excellent performance of the broadband antennas over the entire E-band by setting up a short-range wireless link transmitting a 1 Gbps data signal.     

Acetylcholinesterase voltammetric biosensors based on carbon nanostructure-chitosan composite material for organophosphate pesticides

A sensitive biosensor for chloropyrifos (CPF), an organophosphorus pesticide, was developed by immobilizing acetylcholinesterase (AChE) through covalent bonding to an oxidized exfoliated graphite nanoplatelet (xGnPs)–chitosan cross-linked composite. Because of the increased surface area and the conductive properties of the nanomaterial, AChE developed a high affinity for acetylthiocholine (ATCI) and formed thiocholine with a fast response. The response of the sensor was a linear function of ATCI concentration in two segments, one from 0.005 to 0.039 mM and the second from 0.064 mM to 0.258 mM. The corresponding equation for the first range was i_p(A) = 2.26 × 10^? 5c + 4.39 × 10^? 7 (R² = 0.992) and the equation for the second was i_p(A) = 6.80 × 10^? 6c + 1.30 × 10^? 6 (R² = 1.000), with a detection limit of 1.58 × 10^? 10 M. The fabrication of the sensor was simple, the response was fast and the stability acceptable. This sensor has many potential applications, the foremost being in organophosphorus pesticides.     

非对称耦合量子阱的二次谐波产生与量子阱参数关系研究

采用反射式二次谐波产生 (SHG)方法对非对称Ⅱ Ⅵ族耦合量子阱Zn1 -xCdxSe ZnSe的非线性光学特性进行了研究。非中心对称性和阱间耦合效应在很大程度上增强了材料的非线性效应。发现在入射光和反射光均为p偏振 ,以及入射光和反射光分别为s偏振和p偏振两种情况下 ,SHG信号都随Cd含量x的增大而减小。与ZnSe基体材料相比 ,非对称耦合量子阱 (ACQW)在可见光波段的SHG信号增强一个量级以上。同时发现SHG信号随入射光偏振角的变化而周期性地变化。     

Impact strength elastomer composites based on polystyrene components separated from waste electrical and electronic equipment

The reuse of plastic components of waste electrical and electronic equipment (WEEE) is an important concern both for environmental issues and to preserve the material resources, with minimum energy consumption. Considering that polystyrene fraction was reported as approximate 80% of the total amount of WEEE plastic, this article aims to evaluate the recycling of this fraction, without separation by components, by melt compounding with styrene-butadiene block-copolymer (SBS) and hydrogenated and maleinized SBS, the blend of the two elastomers acting both as an impact modifier and compatibilizer. The composites are characterized by mechanical analysis, impact tests, dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, energy dispersive X-ray analysis, and X-ray diffraction. The recycling conditions of the polystyrene fraction as composites without eliminating the WEEE additives for improved UV and flame resistance, with physical mechanical properties comparable to those of high-impact polystyrene resulted from the study. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48329.     

Electrostatic Charges on Clays

Cation charges present on the surfaces of clay minerals are expected to play a major role in industrial processes involving dry electrostatic separation of granular mixtures containing clay particles. A recent promising potential application has been the removal of clay from British Columbia pulverized coals prior to burning. The clay minerals kaolinite and montmorillonite form the main component of the ash in most Canadian coals: kaolinite is eastern coals and montmorillonite in western coals. The electric charges present on the surfaces of the clay mineral kaolinite have been analyzed from an application point of view, namely, for their ability to transfer onto and remain on other surfaces after contact and separation. Kaolinite samples homoionized with calcium and sodium were prepared from natural kaolin, and the charge transfer after contact and separation with coal was compared for various dry densities of the kaolinite. The results show the following. 1) The electric charge transfer from calcium kaolinite is substantially larger than that from both the sodium kaolinite and natural kaolinite. Charge transfer from untreated montmorillonite exceeds that from all kaolinite samples. 2) The charge transfer after 100 contacts is inversely proportional to the dry density of the clay on a semilog scale. The phenomenon is believed to be related to the changes which occur in the total contact area and in the electrical conductivity of the clay.     

Spectroscopic Analysis of a Corona Space Charge in a Cylindrical System with Air-Carbon Dioxide Medium

Positive corona glow discharge was studied in a system with cylindrical geometry in air and air-carbon dioxide mixtures at normal temperature and pressure (NTP). A spatially resolved spectroscopy technique was used in an attempt to explain the previously observed anomalous charging of particles traveling through the glow region. The results corroborate the existence of the previously reported anomaly. The apparatus developed for taking the spatially resolved spectra and the methods employed may be of interest in fundamental studies of corona discharge behavior in a practical electrostatic precipitator system.     

Ozonation of Substituted Phenols in Aqueous Solutions over CuO-Al2O3 Catalyst

The oxidation of aqueous solutions of substituted phenols, chlorophenols (CPs) and nitrophenols (NPs), at 21±0.5°C and atmospheric pressure, by ozone over a copper–alumina catalyst system was studied. The total disappearance of phenol compounds for 15 to 30 minute reaction times was observed. The presence of the catalyst increased the reaction rate, diminished the ozone consumption and caused an advanced degradation of phenols. A number of six by-products was identified by gas chromatography/mass spectrometry technique (GC/MS), with or without silylation. Based on the experimental data several mechanistic suggestions for the catalytic ozonation are made.     

Mo的表面脉冲激光氮化

激光脉冲辐照置于氮气中的Ｍｏ使表面形成含γ－Ｍｏ２Ｎ的氮化层，激光使Ｍｏ表面熔化导致液相氮化反应，用ＳＥＭ、ＸＲＤ和ＡＵＧＥＲ谱分析表征了氮化层，激光在表层相起的加热和激波效应还有使表层微观组织致密的作用。