The role of biosensors in coronavirus disease-2019 outbreak

Herein, we have summarized and argued about biomarkers and indicators used for the detection of severe acute respiratory syndrome coronavirus 2. Antibody detection methods are not considered suitable to screen individuals at early stages and asymptomatic cases. The diagnosis of coronavirus disease 2019 using biomarkers and indicators at point-of-care level is much crucial. Therefore, it is urgently needed to develop rapid and sensitive detection methods which can target antigens. We have critically elaborated key role of biosensors to cope the outbreak situation. In this review, the importance of biosensors including electrochemical, surface enhanced Raman scattering, field-effect transistor, and surface plasmon resonance biosensors in the detection of severe acute respiratory syndrome coronavirus 2 has been underscored. Finally, we have outlined pros and cons of diagnostic approaches and future directions.     

Roles of organic intercalation agent with flame retardant groups in montmorillonite (MMT) in properties of polypropylene composites

Three kinds of organic intercalation agent containing flame retardant groups, melamine (MA), triphenylphonium (TPP) chloride, and tetradecyl trihexyl phosphonium (TTP) bromide were intercalated into montmorillonite (MMT) via cation exchange reactions. These modified MMTs are combined with intumescent systems and compounded with PP. The flame retardant and thermal properties of the PP composites are studied. The organic intercalation agents in the layers of MMT play important roles in the char formation and flame retardant properties of PP composites. MA shows a better performance in limiting oxygen index (LOI) value and TPP helps to increase UL‐94 properties, whereas TTP maintains or deteriorates the flame retardancy of polypropylene/intumescent flame retardant (IFR) composites. The LOI and UL‐94 properties increase firstly and then decrease as the content of MMT increases. The MA acts as a blowing agent and emits an inert gas to provide migration impetus, which results in a better intumescent structured and stronger char to endure heat erosion. Although TPP and TTP emit combustible gas that burn, especially for TTP as it has a more flammable aliphatic chain. The synergistic effect between MA‐MMT and IFR is better than that for TPP‐MMT and TTP‐MMT. Copyright © 2014 John Wiley & Sons, Ltd.     

气体雪崩放电的单光子测量时间谱

用单光子时间分辨测量技术,研究了伴随有限正比、自猝灭流光(SQS)和G-M三种放电模式光发射的时间特性.结果表明:SQS相对于原初雪崩有一段时间延迟,约几到十几ns,流光的持续时间在10—30ns范围,且与猝灭气体浓度和工作电压有关;伴随G-M雪崩时的光脉冲持续时间长达约1μs,而有限正比只有4ns.本文还清楚地显示了三种模式雪崩放电过程特征的区别.     

Ruthenium nanoparticles polymer-protected on beta zeolite: characterization and catalytic properties in benzene hydrogenation

Summary Ruthenium nanoparticles supported on zeolite Beta catalysts were prepared by alcohol reduction of RuCl₃solution in the presence of PVP. Highly dispersed Ru nanoparticles with mono-size formed on the zeolite surface and their size can be controlled by changing the amount of PVP at same ruthenium loading. In the water/benzene system, Ru-PVP/Beta catalyst for benzene hydrogenation showed high activity, selectivity and good stability.     

High loading MnO2 nanowires on graphene paper: Facile electrochemical synthesis and use as flexible electrode for tracking hydrogen peroxide secretion in live cells

Recent progress in flexible and lightweight electrochemical sensor systems requires the development of paper-like electrode materials. Here, we report a facile and green synthesis of a new type of MnO₂ nanowires–graphene nanohybrid paper by one-step electrochemical method. This strategy demonstrates a collection of unique features including the effective electrochemical reduction of graphene oxide (GO) paper and the high loading of MnO₂ nanowires on electrochemical reduced GO (ERGO) paper. When used as flexible electrode for nonenzymatic detection of hydrogen peroxide (H₂O₂), MnO₂–ERGO paper exhibits high electrocatalytic activity toward the redox of H₂O₂ as well as excellent stability, selectivity and reproducibility. The amperometric responses are linearly proportional to H₂O₂ concentration in the range 0.1–45.4 mM, with a detection limit of 10 μM (S/N = 3) and detection sensitivity of 59.0 μA cm⁻² mM⁻¹. These outstanding sensing performances enable the practical application of MnO₂–ERGO paper electrode for the real-time tracking H₂O₂ secretion by live cells macrophages. Therefore, the proposed graphene-based nanohybrid paper electrode with intrinsic flexibility, tailorable shapes and adjustable properties can contribute to the full realization of high-performance flexible electrode material used in point-of-care testing devices and portable instruments for in-vivo clinical diagnostics and on-site environmental monitoring.     

An efficient and reusable silica/dendrimer supported platinum catalyst for electron transfer reactions

A series of Pt nanoparticles (NPs) smaller than 3 nm were successfully encapsulated in dendrimer/SBA-15 organic and inorganic hybrid composite. The obtained catalysts were characterized by XPS, XRD and TEM. The results of XPS and XRD indicate the existence of Pt NPs in the hybrid matrix. TEM images display the Pt NPs with narrow size distribution are monodispersed in SBA-15 channels. Catalytic property of the supported Pt catalysts was investigated in inorganic (ferricyanide to ferrocyanide by thiosulfate) and organic (p-nitrophenol to p-aminophenol by sodium borohydride) electron transfer (redox) reactions. In both cases, the reduction reactions followed smoothly and the catalysts showed excellent catalytic activity. Moreover, the catalysts can be easily separated and reused several times preserving good catalytic performance.     

高温固相法合成长余辉发光材料Sr_(0.96)Al_2O_4:Eu_(0.02)~(2+),Dy_(0.02)~(3+)

以高温固相法合成了Sr0.96Al2O4:Eu2+0.02,Dy3+0.02长余辉发光材料,其激发光谱和发射光谱均为宽带谱,激发光谱为300～480nm,具有从紫外到蓝绿光波段能量的吸收范围.随着稀土元素Eu2+掺杂量的增加,发光强度逐渐增强,当Eu2+掺杂量达到2(mol)%时,材料的发光强度最大.辅助激活剂Dy3+的添加能显著改善材料的余辉性能.Sr0.96Al2O4:Eu2+0.02,Dy3+0.02在25W日光灯激发30min后,黑暗环境中余辉长达3h.     

Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection

This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose.     

镧掺杂纳米TiO2应用助剂筛选及其对农药残留的光催化降解效果

通过润湿分散剂(十二烷基苯磺酸钠ABS-Na、木质素磺酸钠SL和羧甲基纤维素钠CMC)和载体(白炭黑、高岭土)的筛选,确定了60%稀土镧掺杂纳米TiO2可湿性粉剂(WP)的最优配方。试验结果表明:十二烷基苯磺酸钠为2%,木质素磺酸钠6%,采用高岭土作载体,可湿性粉剂的悬浮率达到了98.12%,润湿时间为4.09 s,且冷贮、热贮合格。通过克百威溶液在太阳光下的消失情况来研究La-TiO2可湿性粉剂的光催化降解效果。试验表明:稀土镧掺杂后的纳米TiO2光催化活性得到了提高,且使用La-TiO2可湿性粉剂能进一步提高克百威的光催化降解效果,当降解效果达最大时,La-TiO2最佳用量为0.2 g.L-1,而直接使用La-TiO2粉末,其最佳用量为0.4 g.L-1。     

考虑空气阻力和地球自转的远程抛射体的研究

针对地球表面坐标系计算远程抛射体落地时间和位置的不足,通过两种方法获得远程抛射体的落地信息. 首先通过在地球表面建立空间直角坐标系计算出考虑空气阻力和地球自转情况下任意抛射角的抛射体的解析解,然后获得了在地球表面所建立的空间直角坐标系与地心坐标系的转换关系式,以抛射体与地心的距离为地球半径作为落地点的条件来计算落地时间和落地位置. 另外,采用球面坐标系表示抛射体的位置、速度及加速度,通过数值计算方法获得抛射体的落地信息. 两种方法所得的结果比较接近,因此两种方法来获得远程抛射体的落地信息都是可行的.