Tin‐Catalyzed Selective Reductive Hydroamination of Alkynes for the Synthesis of Tertiary Amines

A unique preference of tin(II) for aniline activation is disclosed. In the present work tin(II) triflate‐catalyzed highly selective Markovnikov reductive hydroamination of internal as well as terminal alkynes is reported. The mechanistic study revealed the involvement of two steps in one pot wherein alkyne reduces to corresponding alkene in presence of PMHS as reducing agent followed by hydroamination of alkene. A broad range of alkynes transformed into tertiary amines with good to excellent yield. This method is equally applicable in synthesis of secondary amines.

     

Parametric Evaluation of Heat Recovery Steam Generator (HRSG)

Thermal efficiency of a combined cycle power plant depends strongly on a heat recovery steam generator (HRSG), which is the link between the gas turbine‐based topping cycle and steam turbine‐based bottoming cycle. This work is based upon the design of physical parameters of a HRSG. In this article, the physical parameters of a HRSG have been considered to study their implications on HRSG design by comparing the existing plant design with an optimized plant design. Thermodynamic analysis of HRSG for the two designs gives important outcomes which are useful for power plant designers. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21106     

Phosphorylated cardanol prepolymer-grafted carboxylated styrene–butadiene rubber for better processing with enhancing silica filler dispersion

Cardanol is a byproduct of cashew industry of semiforest origin. It is cheap and available in humongous amount and acts as a multifunctional additive in rubber compounds. It can be oligomerized with orthophosphoric acid to make phosphorylated cardanol prepolymer (PCP). Hence, cardanol has been chemically grafted on to the backbone chain of carboxylated styrene–butadiene rubber (XSBR) by employing melt grafting technique in presence of peroxide initiator to include multifunctional properties. The PCP-grafted XSBR (PCP-g-XSBR) was characterized by using Fourier transform infrared spectroscopy and ¹H-NMR techniques and optimize the grafting conditions such as percent of grafting and grafting efficiency by using Taguchi methodology. PCP-g-XSBR was compounded with silica filler for a comparative study in terms of processing behavior with XSBR. The cure characteristics such as the cure rate and the optimum cure time of the unfilled PCP-g-XSBR compounds were determined by oscillating disc rheometer. The thermal analysis of PCP-g-XSBR vulcanizate exhibits slightly better thermal stability as well as plasticization effect. Morphological behaviors also display the less cracked and filled fracture surfaces with better filler dispersion in PCP-g-XSBR vulcanizate. The mechanical properties of the compounded PCP-g-XSBR vulcanizates also improve compare to XSBR vulcanizates. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47528.     

Sensing behaviour of nanosized zinc-tin composite oxide towards liquefied petroleum gas and ethanol

A chemical route has been used to synthesize composite oxides of zinc and tin. An ammonia solution was added to equal amounts of zinc and tin chloride solutions of same molarities to obtain precipitates. Three portions of these precipitates were annealed at 400, 600 and 800 °C, respectively. Results of X-ray diffraction and transmission electron microscopy clearly depicted coexistence of phases of nano-sized SnO₂, ZnO, Zn₂SnO₄ and ZnSnO₃. The effect of annealing on structure, morphology and sensing has been observed as well. It has been observed that annealing promoted growth of Zn₂SnO₄ and ZnSnO₃ at the expense of zinc. The sensing response of fabricated sensors from these materials to 250 ppm LPG and ethanol has been investigated. The sensor fabricated from powder annealed at 400 °C responded better to LPG than ethanol.     

Cardiovascular flow simulation at extreme scale

As cardiovascular models grow more sophisticated in terms of the geometry considered, and more physiologically realistic boundary conditions are applied, and fluid flow is coupled to structural models, the computational complexity grows. Massively parallel adaptivity and flow solvers with extreme scalability enable cardiovascular simulations to reach an extreme scale while keeping the time-to-solution reasonable. In this paper, we discuss our efforts in this area and provide two demonstrations: one on an extremely large and complex geometry (including many of the major arteries below the neck) where the solution is efficiently captured with anisotropic adaptivity and another case (severe abdominal aorta aneurysm) where the transitional flow leads to extremely large meshes (O(10⁹)) and scalability to extremely large core counts (O(10⁵)) for both rigid and deforming wall simulations.     

Syntax optimization for and parsing of patterns

Theory and algorithm for optimization of a directed and labeled tree are presented. Their application for optimizing any finite pattern grammar represented in the form of a tree is discussed. Tree optimization leads to loss information which is essential for identification of patterns. Special technique for preserving this information has been suggested.Finally, outlines of two different algorithms for the parsing of patterns are included. The tree parser uses the optimized tree and the table-driven parser uses the optimized syntax stored in four separate tables.     

Ions Matter: Description of the Anomalous Electronic Behavior in Methylammonium Lead Halide Perovskite Devices

Carrier transport in methylammonium lead iodide (MAPbI₃)‐based hybrid organic–inorganic perovskites (HOIPs) is obscured by vacancy‐mediated ion migration. Thus, the nature of migrating species (cation/anion) and their effect on electronic transport in MAPbI₃ has remained controversial. Temperature‐dependent pulsed voltage–current measurements of MAPbI₃ thin films are performed under dark conditions, designed to decouple ion‐migration/accumulation and electronic transport. Measurement conditions (electric‐field history and scan rate) are shown to affect the electronic transport in MAPbI₃ thin films, through a mechanism involving ion migration and accumulation at the electrode interfaces. The presence of thermally activated processes with distinct activation energies (E_a) of 0.1 ± 0.001 and 0.41 ± 0.02 eV is established, and are assigned to electromigration of iodine vacancies and methylammonium vacancies, respectively. Analysis of activation energies obtained from electronic conduction versus capacitive discharge shows that the electromigration of these ionic species is responsible for the modification of interfacial electronic properties of MAPbI₃, and elaborates previously unaddressed issues of “fast” and “slow” ion migration. The results demonstrate that the intrinsic behavior of MAPbI₃ material is responsible for the hysteresis of the solar cells, but also have implications for other HOIP‐based devices, such as memristors, detectors, and energy storage devices.     

Automated adaptive cardiovascular flow simulations

We present an automatic adaptive procedure to perform blood flow simulations in the cardiovascular system. The procedure allows the user to start with subject-specific data collected through clinical measurements, like magnetic resonance imaging (MRI) data, and evaluate physiological parameters of interest, like flow distribution, pressure variations, wall shear stress, in an automatic and efficient manner. The process involves construction of geometric models of blood vessels, specification of flow conditions and application of an adaptive flow solver. The latter is based on incompressible Navier–Stokes equations using adaptive spatial discretization (meshing) techniques. In this article, we demonstrate the method on a model of a human abdominal aorta of a normal subject with geometry and flow rates assimilated from MRI data. The results obtained show that boundary layer mesh adaptivity offers a better alternative leading to more accurate predictions, especially for key physiological quantities like wall shear stress.     

Formulation Aspects and Effect of Critical Factors for Designing Extended Release Pellets: An Updated Review

Nowadays, pellets are playing a dominating role in the world of multiparticulate oral drug delivery. These pellets have many advantages over single-unit dosage forms like extended release. The present review highlights various formulation aspects for the designing of extended release pellets with a special emphasis on effect of key formulation variables. Design includes pellets–matrix and pellets–reservoir systems. Formulation variables such as effect of polymer, plasticizer, pore former, pH adjuster, antitacking agents, and wetting liquids are considered as key formulation variables. The authors lead to a conclusion that designing approaches and formulation factors should be considered and will assist while preparing extended release pellets.     

Generalized buckling analysis of laminated plates with random material properties using stochastic finite elements

A generalized layer-wise stochastic finite element formulation is developed for the buckling analysis of both homogeneous and laminated plates with random material properties. The pre-buckled stresses are considered in the derivation of geometric stiffness matrix and the effect of variation in these stresses on the mean and coefficient of variation of buckling strength is studied. The mean buckling strength of plates under uniform stress assumption exactly matches with those reported in the literature. However, it is shown that the actual mean buckling strength of plates can be significantly different based on the pre-buckled stress analysis which depends on boundary constraints, principal material directions, aspect and thickness ratios of plates. The statistics of buckling strength is determined using a Taylor series expansion based mean centered first order perturbation technique. The stochastic finite element solutions obtained using layer-wise plate theory is also validated with analytical solutions presented in this paper. Parametric studies are conducted for different aspect ratios, ply orientations and boundary conditions.