Fabrication of a Novel Polymeric Scaffold for Amperometric Laccase Biosensor

Present work displays the preparation of an electrochemical biosensor using a conjugated polymer and laccase enzyme for catechol quantification in samples. The biosensing system is based on an enzyme immobilization on polymer modified graphite transducer surface. For that purpose, a random conjugated polymer, thienothiophene‐benzoxadiazole‐alt‐benzodithiophene (BOTT), was coated onto a graphite electrode surface via drop casting method followed by immobilization of a biomolecule (laccase) for sensing experiments. Herein, for the first time, we proposed a BOTT polymer as an inexpensive and effective way to fabricate highly sensitive and fast response biosensors. The proposed sensing system possessed superior properties with 0.38 μM limit of detection and 110.81 μA mM^?1 sensitivity. Furthermore, cyclic voltammetry and scanning electron microscopy techniques were used to examine the surface modifications. The proposed system could be useful for many future studies for catechol quantification in environmental samples.© 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2333–2339     

A study on 3-D stress distributions in the bi-adhesively bonded T-joints

In this study, the normal (σ_x, σ_y, σ_z) and shear stress (τ_xy, τ_yz, τ_zx) distributions occurring in a bi-adhesively bonded T-joint with was investigated via a non-linear three dimensional finite element analysis. For this purpose, first of all, using 2024-T3 aluminum alloy as the adherend and the support, a two-part paste (DP 460) and a film type (SBT 9244) as adhesive, two different types of T-joint samples (single-adhesively bonded T-joint and bi-adhesively bonded T-joint) were produced for experimental studies. After experimental studies on the three different T-joint types were conducted, stress analyses in the T-joints were performed with a three-dimensional finite element analysis by considering the geometrical non-linearity and the material non-linearities of the adhesive (DP460 and SBT9244) and adherend (AA2024-T3). Finally, for a given adherend, the lower the stiffness of the adhesive used in the overlap, the lower the stress concentration, leading to potentially higher joint strength. The use of relatively low stiffness adhesives at the ends of the overlap in a bi-adhesive can decrease the stress concentration and, therefore, potentially lead to higher joint strength.     

Enantioselective Addition of Diethylzinc to Aromatic Aldehydes Using Chiral Oxazoline-Based Ligands

Russian Journal of Organic Chemistry - Chiral oxazoline ligands containing an aromatic ring were prepared from norephedrine and pyrrole-2-carbonitrile or 2-hydroxybenzoyl chloride. The synthesized...     

Quantification of volatile sulfur compounds related to the corrosion of concrete sewers

Summary A gas-chromatographic procedure for the determination of volatile sulfur compounds related to the formation of the substrate for sulfuric acid producing thiobacilli is described. Volatile sulfur compounds from head-space samples of the sewer atmosphere are qualitatively and quantitatively determined with a sulfur-selective detector. The concentrations are correlated with the occurrence of concrete corrosion in sewage systems.

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Quantifizierung flüchtiger Schwefelverbindungen im Zusammenhang mit der Korrosion von Beton-Abwasserkanälen

Zusammenfassung Es wird ein gas-chromatographisches Verfahren zur Bestimmung flüchtiger Schwefelverbindungen beschrieben, die mittelbar an der Substratbildung für Schwefelsäure bildende Thiobazillen beteiligt sind. Flüchtige Schwefelverbindungen in Original-Luftproben aus Abwassersammlern werden mittels eines für Schwefel selektiven Detektors qualitativ und quantitativ bestimmt und mit dem Auftreten von Betonkorrosion in Abwasserkanälen korreliert.

     

Palladium-pincer complex catalyzed C-C coupling of allyl nitriles with tosyl imines via regioselective allylic C-H bond functionalization

A mechanistically new palladium-pincer complex catalyzed allylation of sulfonimines is presented. This reaction involves C-H bond functionalization of allyl nitriles under mild conditions. The reaction proceeds with a high regioselectivity, without allyl rearrangement of the product. Modeling studies indicate that the carbon-carbon bond formation process proceeds via (eta (1)-allyl)palladium pincer complex intermediates.     

Stereoselective Pincer-complex catalyzed C-H functionalization of benzyl nitriles under mild conditions. An efficient route to beta-aminonitriles

An efficient palladium pincer-complex catalyzed reaction has been developed for alpha-C-H bond functionalization of benzyl nitriles. The studied coupling reaction with sulfonylimines affords beta-aminonitriles with usually high levels of stereoselectivity. The stereoselectivity of the process is highly dependent on the electronic effects of the ortho substituents of the benzyl moiety. Promising levels of enantiomeric excess are obtained using chiral pincer complexes as catalysts.     

Quantum shape effects and novel thermodynamic behaviors at nanoscale

Thermodynamic properties of confined systems depend on sizes of the confinement domain due to quantum nature of particles. Here we show that shape also enters as a control parameter on thermodynamic state functions. By considering specially designed confinement domains, we demonstrate how shape effects alone modify Helmholtz free energy, entropy and internal energy of a confined system. We propose an overlapped quantum boundary layer method to analytically predict quantum shape effects without even solving Schrödinger equation or invoking any other mathematical tools. Thereby we reduce a thermodynamic problem into a simple geometric one and reveal the profound link between geometry and thermodynamics. We report also a torque due to quantum shape effects. Furthermore, we introduce isoformal, shape preserving, process which opens the possibility of a new generation of thermodynamic cycles operating at nanoscale with unique features.     

Natural convection in an inclined quadrantal cavity heated and cooled on adjacent walls

Natural convective flow and heat transfer in an inclined quadrantal cavity is studied experimentally and numerically. The particle tracing method is used to visualize the fluid motion in the enclosure. Numerical solutions are obtained via a commercial CFD package, Fluent. The working fluid is distilled water. The effects of the inclination angle, ? and the Rayleigh number, Ra on fluid flow and heat transfer are investigated for the range of angle of inclination between 0° ? ? ? 360°, and Ra from 10⁵ to 10⁷. It is disclosed that heat transfer changes dramatically according to the inclination angle which affects convection currents inside, i.e. flow physics inside. A fairly good agreement is observed between the experimental and numerical results.     

岩石蠕变模型的比较和修正

对三种岩石在不同的应力下进行了蠕变实验,对蠕变实验曲线用粘弹模型进行了模型参数的反演,结果认为标准线性体、伯格斯和对数模型都是实验曲线的很好近似.为了进一步了解蠕变实验时间对模型参数的影响,研究了蠕变模型的预测功能.将实验蠕变曲线分成二部分,第一部分用于模型参数的反演,第二部分用于模型预测数据的检验.时间外延所得的模型的预测曲线都明显偏离了实测曲线,伯格斯和对数模型的预测曲线比实测曲线偏高,而标准线性体模型则偏低.根据不同时间的蠕变实验数据的比较和分析,认为实验时间对蠕变模型参数的反演有较为明显的影响,但只要对标准线性体模型作适当修正,引入与时间尺度有关的函数C(t),则该模型的预测能力就有较大的提高.