The mosaic structure design to improve the anchoring strength of SiOx@C@Graphite anode

Silicon oxide (SiO_x)-based anodes have aroused great interest as the most promising alternative anode in the practical application of high-performance lithium-ion batteries. However, the electrochemical performance is inhibited because of the large volume change, and the electrode structure deteriorates during the cycling process, which hinders their practical application. In this article, a novel fabrication method for the synthesis of high-performance SiO_x@C@Graphite composites is presented. SiO_x particles are anchored on the graphite surface by chemical vapor deposition and compression molding. This structure makes up the shortcomings of poor electrical conductivity and poor bonding strength between SiO_x and graphite particles. It is beneficial to form a stable solid electrolyte interface and helps to maintain the structural integrity of electrode materials. As a result, the synthetic SiO_x@C@Graphite anode shows a high reversible capacity (2698.8 mA h), excellent cycle stability (about 76.9% capacity retention for 500 cycles) and a superior rate ability. Our research hopes to provide a new idea for improving the bonding strength of the surface coating.     

Tailoring the dielectric properties and energy storage density of 1−x(0.94NaNbO3−0.06SZ)−xBi2O3 through substitution strategy

Energy storage using dielectric capacitors is a growing area of research and development. However, designing a highly performing dielectric capacitor is still a challenge. Despite the excellent results achieved in lead-based dielectrics, lead-free substitutes are essential because of the environmental concerns associated with lead-based products. The lead-free 1?x (0.94NaNbO₃? 0.06SrZrO₃)+ x Bi₂O₃ ceramics abbreviated NNSZ + xB for x = 0.0, 0.05, 0.1, 0.15, and 0.20 was fabricated via solid-state reaction. A recoverable energy density of 2.93 J cm?³ was obtained for NNSZ+0.1B, associated with high thermal stability (25–130 °C), excellent cycling (N = 10⁵), and high efficiency (η) of 83.5%. Moreover, the introduction of Bi₂O₃ significantly improved the electrical insulation (?_r at 1 kHz = 1608 and tan δ = 0.0038) and breakdown strength (380 kVcm?¹) of NNSZ+0.1B by minimizing the formation of sodium, bismuth, and oxygen vacancies. The results obtained in this study provide a benchmark for further investigations on NaNbO₃-based ceramics. More importantly, this study suggests that NNSZ + xB ceramics can be used in pulsed power technology.     

Surface modification of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane in supercritical carbon dioxide for enhancing interfacial strength

PBO fiber is one of the most promising reinforcements in resin matrix composite because of its excellent mechanical properties. However, the inert and smooth surfaces make it the poor interface adhesion with resin matrix, which seriously limits the application in composites. In this article, we report a method to modify the surface of PBO fibers with 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane（BisAPAF）in supercritical CO₂ to enhance interfacial properties. Chemical structures, surface elemental composition and functional groups, and surface morphology were characterized by FT-IR spectrometer, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM), respectively. The mechanical properties of the samples were tested by a tensile tester. Static contact angle and microdebonding tests were used to characterize the wetting ability and interfacial shear strength (IFSS) of the fiber and epoxy resin. The results showed that the BisAPAF could be solved in scCO₂ and introduced more groups, –NH₂, –OH, and –CF₃ on the fiber surface, resulting in the mechanical properties and the wettability of PBO fiber slightly improved. Moreover, the fiber surface roughness was also increased obviously. The IFSS between the modified PBO fiber and epoxy resin increased from 8.18 MPa to 31.4 MPa when the treating pressure was 14 MPa. In general, the method to modify PBO fibers surface using BisAPAF in scCO₂ can effectively improve their interfacial properties.     

Binding Characteristics Study of DNA based Aptamers for E. coli O157:H7

E. coli O157:H7 is a pathogenic bacterium producing verotoxins that could lead to serious complications such as hemolytic uremia syndrome. Fast detection of such pathogens is important. For rapid detection, aptamers are quickly gaining traction as alternative biorecognition molecules besides conventional antibodies. Several DNA aptamers have been selected for E. coli O157:H7. Nonetheless, there has not been a comparative study of the binding characteristics of these aptamers. In this work, we present a comprehensive analysis of binding characteristics including binding affinity (K_d) and binding capacity (B_max) of DNA-based aptamers for E. coli O157:H7 using qPCR. Our results show that aptamer E18R has the highest binding capacity to E. coli 157:H7 and the highest specificity over non-pathogenic E. coli strains K12 and DH5α. Our study also finds that the common biotin-tag modification at 5′ end typically changes the binding capacity significantly. For most of the selected aptamers, the binding capacity after a biotin-tag modification decreases. There exists a discrepancy in the binding capability between the selected aptamer and the aptamer used for detection. Our study also shows that a lower concentration of Mg²⁺ ions in the binding buffer leads to a decrease in the binding capacity of E17F and E18R, while it does not affect the binding capacity of S1 and EcoR1.     

Enhanced Physical and Mechanical Properties of Nitrile-Butadiene Rubber Composites with N-Cetylpyridinium Bromide-Carbon Black

The physical and mechanical properties of nitrile–butadiene rubber (NBR) composites with N-cetylpyridinium bromide-carbon black (CPB-CB) were investigated. Addition of 5 parts per hundred rubber (phr) of CPB-CB into NBR improved the tensile strength by 124%, vulcanization rate by 41%, shore hardness by 15%, and decreased the volumetric wear by 7% compared to those of the base rubber-CB composite.     

Hierarchical Porous Tubular Biochar Based Sensor for Detection of Trace Lead (II)

Hierarchical porous tubular biochar (PTBC) was prepared by selectively removing lignin simply according to reverse the pyrolysis sequence of cellulose. The properties of the PTBC sample were characterized by XRD, SEM, TEM, Raman spectra, cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical performances of PTBC modified on the screen-printing electrode illustrated excellent detection of lead ions (lead (II)) in water with the linear range (0.5–120 μg/L) and the detection limit (0.02 μg/L) by in-situ bismuth film square wave anode stripping voltammetry.     

Surface arcing of insulators due to bentonite contamination

Impulse, alternating and direct voltage tests together with optical observations have been done under clean and polluted surface conditions with respect to bentonite, which is treated as a pollutant. The insulator materials tested were polymethyl methacrylate and polythene. Bentonite pollution may affect several surface flashover characteristics such as voltage at breakdown and 50% breakdown voltage under negative lightning impulse (1.2/50 μs) and the time to breakdown under wet condition for both negative and positive impulse voltage. There are four types of paths taken by the discharge channels, based on which the degree of degradation of the material surface may vary.     

980nm半导体激光器输出光谱特性的改善

为了改善980nm半导体激光器的输出光谱特性,采用传输矩阵分析法推导了双布喇格光纤光栅谐振腔的传输表达式,对布喇格光纤光栅长度和谐振腔腔长对输出光谱的影响进行模拟仿真,结果表明布喇格光纤光栅长度对输出光谱的影响大于谐振腔腔长对输出光谱的影响,加长布喇格光纤光栅长度能压缩输出光谱线宽.在980nm半导体激光器尾纤上写入不同布喇格光纤光栅长度的双布喇格光纤光栅谐振腔,验证了引入双布喇格光纤光栅谐振腔在压缩980nm半导体激光器输出光谱线宽的同时改善了其输出光谱的稳定性.当环境温度在0~75℃范围内变化时,980nm半导体激光器输出中心波长仅变化0.06nm.     

基于光纤锥级联结构的湿度传感器

提出了一种基于普通单模光纤粗锥级联结构的马赫-曾德尔干涉湿度传感器.将两根单模光纤对芯熔融成一个粗锥,并依次级联,形成光纤锥-单模光纤-光纤锥-单模光纤-光纤锥结构.外界环境湿度、温度的改变使传感器的纤芯基模和包层模的光程差发生改变,引起传感器干涉光谱发生变化.通过监测干涉谱波长和能量的变化实现对外界物理量的测量.实验结果表明,当空气中湿度在35~95%RH范围内变化时,传感器的湿度灵敏度为-0.065dB/%RH,线性度为0.997;当温度在30~80℃范围内变化时传感器的温度灵敏度为69.4pm/℃,线性度为0.998.该传感器可以避免温湿度的交叉影响,实现单参量的同时在线区分测量.