Effects of metal support interaction on dry reforming of methane over Ni/Ce-Al2O3 catalysts

Dry (CO₂) reforming of methane is conducted over two newly synthesized Ni20/Ce-γAl₂O₃ and Ni20/Ce-meso-Al₂O₃ catalysts. The x-ray diffraction (XRD) patterns indicated that Ni20/Ce-meso-Al₂O₃ exhibits a better dispersion of nickel, while Ni20/Ce-γAl₂O₃ has larger amounts of nickel crystallites. The temperature programmed desorption (TPD) kinetics analysis indicated that Ni20/Ce-meso-Al₂O₃ had a lesser metal-support interaction than the Ni20/Ce-γAl₂O₃. The thermal gravimetric analysis (TGA) indicated that the incorporation of ceria into the Al₂O₃ matrix helps to stabilize Ni20/Ce-meso-Al₂O₃ during dry reforming of methane. The temperature programmed reduction (TPR) indicated that the synthesized catalysts were sufficiently reducible below 750 °C. A fixed bed reactor evaluation (at 750 °C) showed that both catalysts can facilitate methane reforming to syngas with minimal coking throughout the 30 hours time-on-stream (TOS). However, Ni20/Ce-meso-Al₂O₃ is more promising in terms of prolonged stability for dry reforming applications. Moreover, the syngas yield for Ni20/Ce-γAl₂O₃ is close to equilibrium prediction during the first 1 hour of reaction time.     

Pregnancy by Assisted Reproductive Technology Is Associated with Shorter Telomere Length in Neonates

Telomere length (TL) influences the development of lifestyle-related diseases, and neonatal TL may influence their prevalence. Various factors have been reported to affect neonatal TL. Although the fetus is exposed to multiple conditions in utero, the main factors affecting the shortening of neonatal TL are still not known. In this study, we sought to identify factors that influence fetal TL. A total of 578 mother-newborn pairs were included for TL analysis. TL was measured in genomic DNA extracted from cord blood samples using quantitative PCR. The clinical factors examined at enrollment included the following intrauterine environmental factors: maternal age, assisted reproductive technology (ART) used, body mass index (BMI), gestational diabetes mellitus (GDM), maternal stress, smoking, alcohol consumption, preterm delivery, small-for-gestational-age, neonatal sex, and placental weight. Univariate and multivariate regression analyses were used to verify the relationship between neonatal TL and these clinical factors. The median neonatal TL to single-copy gene ratio was 1.0. Pregnancy with ART was among the 11 factors associated with shorter neonatal TL. From multiple regression analysis, we determined that neonatal TL was significantly shorter for pregnancies in the ART group than in the other groups. We conclude that pregnancy with ART is associated with shorter neonatal TL.     

Studies on urethane‐modified alumina‐filled polyesteramide anticorrosive coatings cured at ambient temperature

Coatings prepared from polyesteramide resin synthesized from linseed oil, a renewable resource, have been found to show improved physicomechanical and anticorrosive characteristics. These properties are further improved when aluminum is incorporated in the polyesteramide resin. The coatings of this resin are generally obtained by baking at elevated temperatures. With a view toward the use of linseed oil, as a precursor for the synthesis of polyesteramide resins and to cure their coatings at ambient temperature, toluylene diisocyanate (TDI) was incorporated into polyesteramide and alumina‐filled polyesteramide in varying proportions to obtain urethane‐modified resins. The latter resins were found to cure at room temperature. The broad structural features of the urethane‐modified polyesteramide and alumina‐filled polyesteramide were confirmed by FTIR and ¹H–NMR spectroscopies. Scratch hardness; impact resistance; bending resistance; specular gloss; and resistance to acid, alkali, and organic solvents of the coatings of these resins were determined by standard methods. Physicomechanical and anticorrosive properties, specular gloss, and thermal stability of the urethane‐modified alumina‐filled polyesteramide coatings were found to be at higher levels among these resins. It was found that TDI could be incorporated in polyesteramide up to only 6 wt %, such that above this loading its properties started to deteriorate, whereas alumina‐filled polyesteramide could take up to 10 wt % TDI. Explanation is provided for the increase in scratch hardness and impact resistance above 6 and 10 wt % addition of TDI in polyesteramide and alumina‐filled polyesteramide, respectively, as well as for the decrease in flexibility and resistance to solvents, acid, and alkali of coatings of these resins above these limits of TDI addition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1855–1865, 2001     

Phase Transformation of Metastable ZnSnO3 Upon Thermal Decomposition by In‐Situ Temperature‐Dependent Raman Spectroscopy

Temperature‐dependent in‐situ Raman spectroscopy is used to investigate the phase transformation of zinc metastannate (ZnSnO₃) to zinc orthostannate (Zn₂SnO₄) induced upon annealing in the ambient. ZnSnO₃ microcubes (MCs) were synthesized at room temperature using a simple aqueous synthesis process, followed by characterization using electron microscopy, X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Annealing of the ZnSnO₃ MCs was carried out up to 1000°C, while recording the Raman spectra in‐situ at regular intervals. Phase transformation from metastannate to orthostannate was found to begin around 500°C with an activation energy of ~0.965 eV followed by the recrystallization into the inverse spinel orthostannate phase at ~750°C. Results from this study provide detailed understanding of the phase transformation behavior of perovskite ZnSnO₃ to inverse spinel Zn₂SnO₄ upon thermal annealing.     

Aloe vera gel: a new thickening agent for pigment printing

An attempt was made to print cotton fabric with pigments using a new thickening agent based on Aloe vera gel in combination with sodium alginate. The results were compared with the standard conventional printing recipe containing synthetic thickener, and a favourable effect of Aloe vera introduction was achieved. The results show that the properties of the printed fabric (sharpness, colour yield, overall fastness properties, softness, and water vapour transmission) are dependent on the percentage of Aloe vera gel in the thickener combination, the concentration of printing auxiliaries, and the curing conditions. Optimal printing properties were achieved by using a printing paste containing 80% Aloe vera/20% sodium alginate (700 g kg^?1), pigment (50 g kg^?1), binder (145 g kg^?1), fixer (10 g kg^?1), and ammonium sulfate (5 g kg^?1), followed by drying at 85 °C for 5 min and curing at 150 °C for 3 min. The sample printed with the new recipe showed superior rubbing fastness and handle properties, with a slightly lower colour yield, when compared with the sample printed with synthetic thickener. Finally, economic issues arising from synthetic thickener substitution are highlighted.     

Investigation of Dissipation,Adsorption, Degradation,and Leaching of Triazophos Pesticide in Various Soils

This study concerns the investigation of dissipation, adsorption, and degradation of triazophos in different soils from Pakistan. These processes help in the disappearance of pesticide from the environment. Gas chromatography was used for dissipation and adsorption analysis while for degradation study mass spectrometer was used in addition of gas chromatography (GC-MS). The dissipation rate of triazophos in three different soils was 90% over 30 days with average half-life of 9.059 days. From dissipation study it was inferred that rate is variable in each soil due to climatic changes, soil nature and soil-pesticide interactions. Adsorption experiment has revealed that the adsorption of this pesticide to soil follows the pseudo first order kinetic model with rate constant value of 0.479/h and Freundlich isotherm with adsorption capacity of 1.832 mol/g. Degradation study has displayed two major metabolites, one is phosphorothioic acid, S-[2-[(1-cyano-1-methylethyl) amino]-2-oxoethyl] O,O-diethyl ester at retention time of 9.136 and the other is sulfotep at 14.304 min. The leaching potential of triazophos was also calculated from its half-life and organic carbon content present in soil which was 1.688 representing it as non leacher pesticide.     

Modulation Role of Abscisic Acid (ABA) on Growth, Water Relations and Glycinebetaine Metabolism in Two Maize (Zea mays L.) Cultivars under Drought Stress

The role of plant hormone abscisic acid (ABA) in plants under drought stress (DS) is crucial in modulating physiological responses that eventually lead to adaptation to an unfavorable environment; however, the role of this hormone in modulation of glycinebetaine (GB) metabolism in maize particularly at the seedling stage is still poorly understood. Some hydroponic experiments were conducted to investigate the modulation role of ABA on plant growth, water relations and GB metabolism in the leaves of two maize cultivars, Zhengdan 958 (ZD958; drought tolerant), and Jundan 20 (JD20; drought sensitive), subjected to integrated root-zone drought stress (IR-DS) simulated by the addition of polyethylene glycol (PEG, 12% w/v, MW 6000). The IR-DS substantially resulted in increased betaine aldehyde dehydrogenase (BADH) activity and choline content which act as the key enzyme and initial substrate, respectively, in GB biosynthesis. Drought stress also induced accumulation of GB, whereas it caused reduction in leaf relative water content (RWC) and dry matter (DM) in both cultivars. The contents of ABA and GB increased in drought-stressed maize seedlings, but ABA accumulated prior to GB accumulation under the drought treatment. These responses were more predominant in ZD958 than those in JD20. Addition of exogenous ABA and fluridone (Flu) (ABA synthesis inhibitor) applied separately increased and decreased BADH activity, respectively. Abscisic acid application enhanced GB accumulation, leaf RWC and shoot DM production in both cultivars. However, of both maize cultivars, the drought sensitive maize cultivar (JD20) performed relatively better than the other maize cultivar ZD958 under both ABA and Flu application in view of all parameters appraised. It is, therefore, concluded that increase in both BADH activity and choline content possibly resulted in enhancement of GB accumulation under DS. The endogenous ABA was probably involved in the regulation of GB metabolism by regulating BADH activity, and resulting in modulation of water relations and plant growth under drought, especially in the drought sensitive maize cultivar JD20.     

Kinetics of oxidative cracking of n‐hexane to olefins over VOx/Ce‐Al2O3 under gas phase oxygen‐free environment

The kinetics of oxidative cracking of n‐hexane to olefins using lattice oxygen of VO_x/Ce‐Al₂O₃ is investigated. The TPR/TPO analysis shows a consistent reducibility (79%) of VO_x/Ce‐Al₂O₃ in repeated redox cycles. The total acidity of the sample is found to be 0.54 mmol/g with 22% are strong acid sites that favors olefin selectivity. The oxidative cracking of n‐hexane in a fluidized CREC Riser simulator gives approximately 60% olefin selectivity at 30% n‐hexane conversion. A kinetic model is developed considering (1) cracking, (2) oxidative dehydrogenation (ODH), and (3) catalyst deactivations. The proposed cracking mechanism considers adsorption, C–H and C–C bond fission and desorption as elementary steps and implemented by pseudo steady state hypothesis. A Langmuir‐Hinshelwood mechanism is found to represent the ODH reactions. The developed model fits the experimental data with favorable statistical indicators. The estimated specific reaction rate constants are also found to be consistent with the product selectivity data. © 2016 American Institute of Chemical Engineers AIChE J, 63: 130–138, 2017     

Glass microparticle- versus microsphere-filled experimental dental adhesives

This study aimed to formulate antibacterial dental adhesives. Phosphate-substituted methacrylate adhesives were modified with 0–20 wt % copper-doped glass microparticles. Two shapes of microparticles were used: regular shaped (microspheres) and irregular shaped (microparticles). The morphology/composition, roughness, monomer conversion (DC%), thermogravimetric analysis, and antibacterial action against S. mutans and P. aeruginosa and ion release were investigated. The results showed that microspheres produced adhesives with a relatively smoother surface than microparticles did. The DC% of adhesives increased with increasing glass filler content. Filled adhesives showed polymer decomposition at ~315 °C and glass melting at 600–1000 °C. The weight loss percent of adhesives decreased with increasing weight percent of fillers. Glass microparticles at 0–20 wt % significantly increased the antibacterial action of adhesives against both bacteria. Glass microspheres at 0–5 wt % significantly increased the antibacterial action of adhesives against both bacteria. Only 20 wt % microparticle-filled adhesive showed an inhibition zone similar to tobramycin (positive control). Microparticle-filled adhesives (with >5 wt % filler) significantly reduced S. mutans more than their microsphere counterparts. Microsphere-filled adhesives (with ≤5 wt % filler) significantly reduced P. aeruginosa more than their microparticle counterparts. Microsphere-filled adhesives showed higher Cu release than their microparticle counterparts. Accordingly, phosphate-substituted methacrylate filled with glass could be used as an antibacterial adhesive. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47832.     

Magnetic,Dielectric and Complex Impedance Properties of xBa_(0.95)Sr_(0.05)TiO_3–(1-x)BiFe_(0.9)Gd_(0.1)O_3Multiferroic Ceramics

xBa_(0.95)Sr_(0.05)TiO_3–(1-x)BiFe_(0.9)Gd_(0.1)O_3[x BST–(1-x)BFGO](x = 0.00, 0.10, 0.20 and 0.25) multiferroic ceramics were prepared by the standard solid-state reaction technique. Structural characterization was performed by X-ray diffraction. All the samples showed rhombohedral distorted perovskite structure. Surface morphology of the ceramics was studied by the field emission scanning electron microscope(FESEM). From the FESEM observation, the grain size was observed to be decreased with increasing BST content. Enhanced magnetic properties were observed in BFGO with the increase in BST content because of large lattice distortion. The complex initial permeability increased with the increasing of BST content. The study of dielectric properties showed that the dielectric constant increased, whereas dielectric loss decreased with increasing of BST content due to the reduction of oxygen vacancies. An analysis of the electric impedance and modulus with frequency was performed at different temperatures. Non-Debye-type relaxation processes occur in the compound which was confirmed from the nature of the Cole–Cole plot. The DC conductivity was found to increase with the rise in temperature which indicates the semiconducting behavior of the compound with characteristics of the negative temperature coefficient of resistance. The activation energy, responsible for the relaxation determined from the modulus spectra(0.246 eV), was found to be almost same as the value obtained from the impedance study(0.240 eV), indicating that charge carriers overcome the same energy barrier during relaxation. The frequency response of imaginary parts of electric impedance and modulus suggested that the relaxation in xB ST–(1-x)BFGO ceramics follows the same mechanism at various temperatures.