Vapor Phase Selective Catalytic Oxidation of Cyclohexane over 13X Supported Metal Oxides in the Presence of Ozone

This article reports the application of ozone for the selective oxidation of cyclohexane over 13X molecular sieve supported various metal oxides at ambient temperatures. From the SEM, XRD and HR-TEM results, the impregnated metal oxides are highly dispersed on the support. The activity results reveal that Co/MS, Mo/MS, Cu/MS, and Ag/MS catalysts produce cyclohexanone/cyclohexanol as selective oxidation products, whereas Ce/MS, Mn/MS, and V/MS catalysts yield, predominantly, CO and CO₂. Among them, Co/MS catalyst exhibits better conversion of 12.2% with selectively of 58% to cyclohexanone/cyclohexanol, which is attributed to the simultaneous activation of ozone and cyclohexane (-C-H bond) at ambient conditions.     

Phase Transformations in Third Generation Gamma Titanium Aluminides: Ti-45Al-(5, 10) Nb-0.2B-0.2C

Third generation γ-titanium aluminides with nominal compositions Ti–45Al–5Nb–0.2B–0.2C and Ti–45Al–10Nb–0.2B–0.2C were investigated to identify the phase transformation and their morphological stability with temperature. Electron microscopy and differential scanning calorimetry were employed for the characterization of phases and for recording the corresponding transformations, respectively. It has been inferred that the order–disorder transformation temperatures α₂ → α increased with increasing Niobium (Nb), while the α-transus temperature decreases. The stability of the microstructure for both alloys with temperature were also investigated. Mass change measured for the heating rates 20 °C s⁻¹ and 30 °C s⁻¹ reveals that the alloy Ti–45Al–10Nb–0.2–0.2C shows stability up to 1100 °C, and the alloy Ti–45Al–5Nb–0.2B–0.2C is stable up to 900 °C. The orientation relationship between the phases indicates that with the change in shape of the α phase from lamellar to equiaxed, it deviates from the Blackburn orientation relationship.

     

The effect of bismaleimide resin on curing kinetics of epoxy–amine thermosets

An analysis of the cure kinetics of several formulations composed of diglycidyl ether of bisphenol-A (DGEBPA) and aromatic diamines, methylenedianiline (MDA) and diaminodiphenyl sulfone (DDS), in the absence and presence of 4,4′-bismaleimidodiphenylmethane (BM) was performed. The dynamic differential scanning calorimetry (DSC) thermograms were analyzed with the help of ASTM kinetic software to determine the kinetic parameters of the curing reactions, including the activation energy, preexponential factor, rate constant, and 60 min ½ life temperature. The effects of substitution of one curing agent for another, their concentration, and the absence and presence of BM resin and its concentration on curing behavior, ethalpy, and kinetic parameters are discussed. © 1996 John Wiley & Sons, Inc.     

Conjugated polymer mediated synthesis of nanoparticle clusters and core/shell nanoparticles

Two water soluble conjugated polymers, poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and ammonium ion stabilized poly(phenylene vinylene) (P2), are found to be able to reduce noble metal ions to zero-valent metals via a direct chemical deposition technique. Au nanoparticle clusters can be obtained through reduction of Au³⁺ ions by PEDOT:PSS and the electronic coupling between them can be controlled by HAuCl₄ concentration. Core/shell Ag/polymer nanostructures are prepared from reduction of Ag⁺ ions by P2, which have a ppb detection limit for 4-MBA using surface-enhanced Raman spectroscopy (SERS). This conjugated polymer mediated synthesis of metal nanoparticles may open a new avenue for fabricating nanomaterials and nanocomposites with tunable optical properties that are dominated by their structure and electronic coupling between nanoparticles.     

Unique Physico-chemical Properties of Sal (Shorea robusta) Starch

Starch from sal seeds cake was isolated, bleached and purified. Scanning electron microscopy of the starch showed round to oval shaped granules of the size 3.5 to 12.3 μm. The starch has more nitrogen, phosphorus, lipids, amylose and water binding capacity in comparison to the other starches of forest origin. Despite its low and seemingly restricted swelling, the sal starch is much more soluble at any particular degree of swelling. Paste viscosity curve showed no drop in viscosity after full gelatinisation had taken place, i. e. the paste is stable on continued cooking.     

Room temperature hydrogen gas sensors of functionalized carbon nanotubes based hybrid nanostructure: Role of Pt sputtered nanoparticles

Fast detection of H₂ gas at room temperature has constantly remained a challenge. The metal-oxide based gas sensors have shown excellent sensing properties for gases like H₂, NO, CO and NH₃. In the present work, the H₂ gas sensing characteristics of multiwalled carbon nanotubes based hybrid sensor (F-MWCNTs/TiO₂/Pt) has been reported. The fabricated sensor shows 3.9% sensitivity for low concentration i.e. 0.05% of H₂ with good repeatability and stability at room temperature. The sensing response of F-MWCNTs/TiO₂/Pt is interrelated to change in their resistance on the introduction of H₂ gas and this phenomenon is required for deep understanding the effect of H₂ adsorption on their electronic conduction. The improvement in sensitivity of F-MWCNTs/TiO₂/Pt as compared to MWCNTs/TiO₂ towards H₂ is because of the catalytic role of dispersed Pt nanoparticles deposited by sputtering.     

Facile synthesis,characterization, and ab-initio DFT simulations of energy efficient NN′ dialkyl 1,4 benzene dicarboxamide monomers recovered from PET bottle waste

Aminolytic chemical recycling is performed for obtaining NN′ diethyl 1,4 benzene dicarboxamide, NN′ dibutyl 1,4 benzene dicarboxamide, and NN′ dihexyl 1,4 benzene dicarboxamide from Polyethylene terephthalate bottle waste. The compounds were characterized through Fourier transform Infrared spectroscopy, Raman spectroscopy, UV–Visible spectroscopy, ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. Thermal properties were also analyzed with the help of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Density Functional Theory (DFT) study has been performed at GGA-BLYP (Becke's and Lee–Yang–Parr) functional using SZ basis set to investigate the vibrational frequencies and physical parameters. Experimental vibrational frequencies were found in good accord with the experimental values. Calorific values of the products have been determined using bomb calorimeter as per standard ASTM D240. The values have been correlated with increment of methylene units from NN′ diethyl BdCA to NN′ dihexyl BdCA using standard molar enthalpies of carbon and hydrogen. SEM and EDX analysis of the char residues after combustion has also been carried out to insight the effect of N-alkyl chain length on calorific values. The calorific values of the recovered compounds are comparable to commercial solid fuels and the compounds may find potential applications in aerospace industry.     

Evaluation of antimicrobial effects of lauric arginate on reduction of Salmonella spp. in ground chicken

The efficacy of lauric arginate (LAE) on Salmonella survivability in ground chicken containing 9.8% fat was determined under refrigerated storage. The effect of LAE treatments on total aerobes, pH and objective colour were also assessed in ground chicken. LAE was highly effective against Salmonella in 0.1% peptone with no detectable survivors following treatment with 200 ppm and 400 ppm of LAE. No difference existed (P > 0.05) in the growth of Salmonella and total aerobes after treatment with 200 and 400 ppm of LAE in ground chicken inoculated with a four strain mixture of Salmonella. At these concentrations, LAE did not exhibit any treatment effect on the pH and colour of ground chicken (P > 0.05). In conclusion, although LAE possesses strong inhibitory (P < 0.05) effect against Salmonella in suspension in 0.1% peptone water, no inhibitory (P > 0.05) effect on growth of Salmonella was observed in ground chicken at the currently approved levels of 200 ppm of LAE.     

Experimental investigation of impact of diesel particulate filter on smoke and NO<Subscript>x</Subscript> emissions of a Euro-I compression ignition engine with active and off-board regeneration

Old engines (Euro III or earlier) produce more emissions, and it will be difficult to entirely stop their usage especially in developing and under-developed nations; hence, it is desired that appropriate emission reduction technologies are tested on such engines to analyze their feasibility and economical acceptability. While most such studies have been conducted on constant speed stationary engines and modern engines, this study tried to analyze the effectiveness of an uncoated wall-flow type ceramic diesel particulate filter on a Euro-I, water-cooled, direct injection, variable speed, compression ignition engine in a laboratory set-up in India. Also, this study focused on diesel particulate filter regeneration by two methods: active regeneration by diesel injection in the particulate filter using an electronic control unit and off-board regeneration by taking out and heating the diesel particulate filter in an electrical resistance furnace at 650 °C for 10 h. The results, in the form of smoke emission, NO_x emission and engine performance, obtained using both the regeneration methods were analyzed, and conclusions were drawn. It was found that using diesel particulate filter, particulate matter emissions (smoke) were almost entirely eliminated. It was also found that off-board regeneration had numerous advantages compared to active regeneration. Since a furnace would be needed for off-board regeneration, an exchange process for diesel particulate filter is suggested.     

Cuckoo search algorithm based satellite image contrast and brightness enhancement using DWT–SVD

This paper presents a new contrast enhancement approach which is based on Cuckoo Search (CS) algorithm and DWT-SVD for quality improvement of the low contrast satellite images. The input image is decomposed into the four frequency subbands through Discrete Wavelet Transform (DWT), and CS algorithm used to optimize each subband of DWT and then obtains the singular value matrix of the low-low thresholded subband image and finally, it reconstructs the enhanced image by applying IDWT. The singular value matrix employed intensity information of the particular image, and any modification in the singular values changes the intensity of the given image. The experimental results show superiority of the proposed method performance in terms of PSNR, MSE, Mean and Standard Deviation over conventional and state-of-the-art techniques.