Thermo-Kinetic Study of Piperazine Immobilized Silica Surface

In the present study, the degradation process of piperazine (PP) immobilized silica gel (SiPP) is investigated under dynamic conditions. The degradation of SiPP is studied with thermogravimetric analyzer (TGA). The kinetics of degradation process is analyzed by Kissinger method, Flynn–Wall–Ozawa's (FWO) method, and Deconvolution method. It is found that degradation of SiPP can be described by parallel independent two-portion process model, which includes two processing state of the system (marked by processes 1 and 2), where process 1 and 2 can be attributed to decomposition processes of organic moiety attached on silica surface. The apparent activation energy (E_a) is calculated by Flynn–Wall–Ozawa's (FWO) method and deconvolution method.     

Normal- and reversed-phase high-performance thin-layer chromatography methods for the simultaneous determination of remogliflozin etabonate and metformin hydrochloride antidiabetic drugs in bulk and tablet formulation

JPC – Journal of Planar Chromatography – Modern TLC - Two new, simple, fast, and sensitive methods, normal- and reversed-phase high-performance thin-layer chromatography (NP-HPTLC and...     

Passivation techniques for InAs/GaSb strained layer superlattice detectors

InAs/(In,Ga)Sb Strained Layer Superlattices (SLSs) have made significant progress since they were first proposed as an infrared (IR) sensing material more than three decades ago. The basic material properties of SLS provide a prospective benefit in the realization of IR imagers with suppressed interband tunneling and Auger recombination processes, as well as high quantum efficiency and responsivity. With scaling of single pixel dimensions, the performance of focal plane arrays is strongly dependent on surface effects due to the large pixels’ surface/volume ratio. This article discusses the cause of surface leakage currents and various approaches of their reduction including dielectric passivation, passivation with organic materials (polyimide or various photoresists), passivation by overgrowth of wider bandgap material, and chalcogenide passivation. Performance of SLS detectors passivated by different techniques and operating in various regions of infrared spectrum has been compared.     

Copper-Catalyzed Intramolecular SEAr Reaction–Oxidation under Aerobic Conditions: Synthesis of Styryl-/Alkenyl-Substituted Xanthone Derivatives

Herein, we report a copper-catalyzed intramolecular electrophilic aromatic substitution (S_EAr)−oxidation process to access a wide range of diversified xanthone derivatives using air as a sole oxidant. Specifically, this protocol affords hitherto unknown styryl-/alkenyl-substituted xanthone derivatives in moderate to high yields. The practicality of the method has been demonstrated by gram-scale syntheses.     

A computationally efficient technique for the solution of non-isothermal nylon-6 polymerization in batch reactors

The kinetic scheme of nylon-6 polymerization consists of ring opening, polyaddition, step growth, reaction with monofunctional acids and cyclization. A set of ordinary differential equations (initial value problem) governing the concentrations and moments of the reacting species and the energy balance for batch reactors has been solved. We proposed a semianalytic technique somewhat similar to the finite element method in which the conversion domain has been divided into sequential subdomains. A series solution for the state variables has been assumed in terms of the incremental conversion of caprolactam in that domain. The coefficients are obtained using the balance equations. This technique of solution takes care of the nonlinearity of the problem in a natural way and involves the sequential evaluation of constant coefficients of the series. It gives comparable results with those from Gear's algorithm (which involves the evaluation of functions) in far fewer steps. Our scheme can be easily implemented on a PC-XT and is considerably faster and more efficient.