Sensitive and Reversible Detection of Methanol and Water Vapor by In Situ Electrochemically Grown CuBTC MOFs on Interdigitated Electrodes

The in situ electrochemical growth of Cu benzene‐1,3,5‐tricarboxylate (CuBTC) metal–organic frameworks, as an affinity layer, directly on custom‐fabricated Cu interdigitated electrodes (IDEs) is described, acting as a transducer. Crystalline 5–7 µm thick CuBTC layers are grown on IDEs consisting of 100 electrodes with a width and a gap of both 50 µm and a height of 6–8 µm. These capacitive sensors are exposed to methanol and water vapor at 30 °C. The affinities show to be completely reversible with higher affinity toward water compared to methanol. For exposure to 1000 ppm methanol, a fast response is observed with a capacitance change of 5.57 pF at equilibrium. The capacitance increases in time followed diffusion‐controlled kinetics (k = 2.9 mmol s^?0.5 g^?1_CuBTC). The observed capacitance change with methanol concentration follows a Langmuir adsorption isotherm, with a value for the equilibrium affinity K _e = 174.8 bar^?1. A volume fraction f _MeOH = 0.038 is occupied upon exposure to 1000 ppm of methanol. The thin CuBTC affinity layer on the Cu‐IDEs shows fast, reversible, and sensitive responses to methanol and water vapor, enabling quantitative detection in the range of 100–8000 ppm.     

Hybridization of stochastic reduced basis methods with polynomial chaos expansions

We propose a hybrid formulation combining stochastic reduced basis methods with polynomial chaos expansions for solving linear random algebraic equations arising from discretization of stochastic partial differential equations. Our objective is to generalize stochastic reduced basis projection schemes to non-Gaussian uncertainty models and simplify the implementation of higher-order approximations. We employ basis vectors spanning the preconditioned stochastic Krylov subspace to represent the solution process. In the present formulation, the polynomial chaos decomposition technique is used to represent the stochastic basis vectors in terms of multidimensional Hermite polynomials. The Galerkin projection scheme is then employed to compute the undetermined coefficients in the reduced basis approximation. We present numerical studies on a linear structural problem where the Youngs modulus is represented using Gaussian as well as lognormal models to illustrate the performance of the hybrid stochastic reduced basis projection scheme. Comparison studies with the spectral stochastic finite element method suggest that the proposed hybrid formulation gives results of comparable accuracy at a lower computational cost.     

Deep desulfurization of diesel via peroxide oxidation using phosphotungstic acid as phase transfer catalyst

High sulfur level in diesel fuel has been identified as a major contributor to air pollutant in term of sulfur dioxide (SO_x) through diesel fueled vehicles. The main aim of the present work is to develop a promising methodology for ultra deep desulfurization of diesel fuel using oxidation followed by phase transfer of oxidized sulfur. Experiments were carried out in a batch reactor using n-decane as the model diesel compound and also using commercial diesel feedstock. To remove sulfur tetraoctylammonium bromide, phosphotungstic acid, and hydrogen peroxide were used as phase transfer agent, catalyst and oxidant respectively. The percent sulfur removal increases with increasing the initial concentration of sulfur in fuel and with increasing the reaction temperature. Similar trends were observed when commercial diesel was used to carry out desulfurization studies. The amphiphilic catalyst serves as a catalyst and also as an emulsifying agent to stabilize the emulsion droplets. The effects of temperature, agitation speed, quantity of catalyst and the phase transfer agent were studied to estimate the optimal conditions for the reactions. The sulfur removal from a commercial diesel by phase transfer catalysis has been found effective and removal efficiency was more than 98%. Kinetic experiments carried out for the desulfurization revealed that the sulfur removal results are best fitted to a pseudo first order kinetics and the apparent activation energy of desulfurization was 30.6 kJ/mol.     

Toughening of AT-Resins with a Polyphenylquinoxaline

Acetylene terminated (AT) resins are addition-curable thermoset materials which do not generate volatiles during cure and therefore can be fabricated into void-free structures. They retain good thermal and mechanical properties even after exposure to high humidity environments. Their use as composite matrix resins and adhesives has shown promise. These resins, however, are brittle. Molecular structure modifications and blending with thermoplastic modifiers have been used to improve their toughness. In this work, improvement in toughness has been sought through the use of a polyphenylquinoxaline (PPQ) modifier. The blended systems showed improvements in toughness, thermooxidative stability, and lap shear strength over the original AT-resins.     

Experimental investigation of an indirect-type solar cooker for indoor cooking based on a parabolic dish collector

In the present research article, an indirect type solar cooking system has been developed for indoor cooking. In the proposed cooking system, a cooking pot has been placed at a distance of 5 m from the parabolic dish collector, and the heat has been transmitted from the collector to the cooking pot by means of heat transfer fluid. A gear pump of 40 W and insulated pipes have been used to circulate the fluid. A number of experiments have been performed to analyze the performance of the cooking system. During the investigation, the system achieved the temperature of the heat transfer fluid up to 175°C. The time taken for cooking the rice and the black grams has been observed 21 and 68min, respectively. The average thermal efficiency of the proposed system for the entire day has been achieved at 13.11%.     

Performance evaluation of CBN,coated carbide,cryogenically treated uncoated/coated carbide inserts in finish-turning of hardened steel

In the present work, the performance of cubic boron nitride (CBN) inserts was compared with coated carbide and cryogenically treated coated/uncoated carbide inserts in terms of flank wear, surface roughness, white layer formation, and microhardness variation under dry cutting conditions for finish turning of hardened AISI H11 steel (48–49 HRC). The flank wear of CBN tools was observed to be lower than that of other inserts, but the accumulated machining time for all the four edges of carbide inserts were nearer to or better than the PCBN inserts. Results showed that tool life of carbide inserts decreased at higher cutting speeds. The surface roughness achieved under all cutting conditions for coated-carbide-treated/untreated inserts was comparable with that achieved with CBN inserts and was below 1.6 μm. The white layer formation and microhardness variation is less while turning with cryogenically treated carbide inserts than the CBN and untreated carbide. At low to medium cutting speed and feed, the performance of carbide inserts was comparable with CBN both in terms of tool life and surface integrity.     

Nonlinear pulse propagation in chalcogenide As2Se3 glass photonic crystal fiber using RK4IP method

Pulse propagation through chalcogenide As(2)Se(3) glass photonic crystal fiber (PCF) is numerically investigated using fourth-order Runge-Kutta in the interaction picture (RK4IP) method. The fully vectorial effective index method (FVEIM) is used to calculate the variation of effective refractive index, effective area, dispersion, and nonlinear coefficient (γ) in As(2)Se(3) PCF with wavelength for different values of pitch and air hole size. The RK4IP method is used to demonstrate the soliton propagation, self-phase modulation (SPM), soliton collision and cross phase modulation (XPM) in the designed As(2)Se(3) PCF. The numerically obtained value of soliton collision length (L(col)=51.3L(D)) using the RK4IP method is found to be in good agreement with the theoretical value of soliton collision length (L(col)=51.408L(D)) obtained from inverse scattering transform method, thus providing a verification of the RK4IP accuracy in solving generalized nonlinear schr?dinger equation (GLNSE). We also evaluate and apply the value of wavelength for distortionless (L(NL)=L(D)) propagation of the soliton pulse.     

A Novel Oxidation of Valine by N-Bromophthalimide in the Presence of Ruthenium(III) Chloride as a Homogeneous Catalyst

Kinetics of Ruthenium(III) [Ru(III)] chloride catalyzed oxidation of valine (Val) has been studied by N-bromophthalimide (NBP) in the acidic medium at 35 °C. The reaction rate follows first-order and zero-order dependence with respect to [NBP] and [Val]. First-order kinetics was observed for Ru(III) chloride at low range of concentrations and tending towards zero-order at higher concentrations. A negative effect was observed for [H⁺] and [phthalimide], while a positive effect was observed for [Cl^?] on the reaction rate. Hg(OAc)₂, ionic strength (I), and dielectric constant (D) of the medium did not change significantly the reaction rate. The rate constants as a function of temperature (298–318 K) were used to calculate activation parameters of the oxidation of Val by NBP. A plausible mechanism was proposed to explain the results of kinetic studies, reaction stoichiometry and product analysis.     

An improved multimodal medical image fusion scheme based on hybrid combination of nonsubsampled contourlet transform and stationary wavelet transform

This research proposes an improved hybrid fusion scheme for non-subsampled contourlet transform (NSCT) and stationary wavelet transform (SWT). Initially, the source images are decomposed into different sub-bands using NSCT. The locally weighted sum of square of the coefficients based fusion rule with consistency verification is used to fuse the detailed coefficients of NSCT. The SWT is employed to decompose approximation coefficients of NSCT into different sub-bands. The entropy of square of the coefficients and weighted sum-modified Laplacian is employed as the fusion rules with SWT. The final output is obtained using inverse NSCT. The proposed research is compared with existing fusion schemes visually and quantitatively. From the visual analysis, it is observed that the proposed scheme retained important complementary information of source images in a better way. From the quantitative comparison, it is seen that this scheme gave improved edge information, clarity, contrast, texture, and brightness in the fused image.