Radiation‐Grafted Polymerization from a Gas Phase to Form Polymeric Layers on Metal Surfaces

Summary: Experimentally it is shown that, under irradiation in an atmosphere of non‐saturated vinylidene chloride vapors, a polymeric layer is formed on the surface of oxidized titanium samples. The thickness of this layer increases with the increase of thickness of the oxide film. Such a dependence corresponds to the current understanding of the mechanism of formation and migration of the active excited centers that initiate grafted polymerization.

Wide range XPS spectra of oxidized titanium samples after PVDC grafting from a gas phase.     

Microwave-assisted novel and efficient one-pot synthesis of fused steroidal and non-steroidal isothiazoles

An efficient microwave promoted one-pot synthesis of steroidal and non-steroidal isothiazole derivatives from corresponding β-bromo-α,β-unsaturated aldehydes has been described using a sodium thiocyanate-urea system. The β-bromo-α,β-unsaturated aldehydes derivatives are efficiently synthesized from corresponding cyclic ketones using Vilsmeir formylation reaction. The synthetic protocol is also applied for the synthesis of antifungal brassilexin.     

Synthesis of Vegetable Oil‐Based Polyurethane: A Study on Curing Kinetics Behavior

In the present study, biobased polyurethane (BPU) samples were synthesized from three different polyols along with polymeric hexamethylene diisocyanate. The three different polyols were synthesized by reacting castor oil with ethylene glycol, triethylene glycol, and triethanolamine. The synthesized polyols were confirmed using proton nuclear magnetic resonance (¹H NMR) spectra analysis. BPU samples were confirmed by the disappearance of isocyanate peak in the FTIR spectra. The cross‐linking densities of all BPU samples were determined using swelling studies. Curing kinetics behavior of all BPU samples were analyzed using differential scanning calorimetry at three different heating rates (5, 7.5, and 10°C/min). The curing kinetic parameters were studied using three nonisothermal methods such as Kissinger, Flynn–Wall–Ozawa, and Ozawa, respectively. The activation energies were found to increase with increasing degree of cure (α). Surface properties of all the synthesized BPU samples were evaluated by dynamic mechanical analysis and scanning electron microscopy.     

Solvatochromicity of 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone for screening of solvents

The quinonic compound 3-hydroxy-4-(1-(2,4-dihydroxyphenyl)-2-hydroxy-2,2-diphenylethylidene)cyclohexa-2,5-dienone (I) is synthesised by the reaction of benzil with 1,3-dihydroxybenzene in basic medium. Solution of this compound shows visibly distinct colour differences in different solvents. From the different absorption maxima of the compound in visible spectra it can be used as an excellent analytical reagent to screen different solvents.     

Beukers-like supercongruences for generalized Apéry numbers

For positive integers \(f_1,f_2,m,l\), the author and Chetry defined a generalization of Apéry numbers \(A(f_1,f_2,m,l,\lambda )\) given by

$$\begin{aligned} A(f_1,f_2,m,l,\lambda ):=\sum _{j=0}^{f_2}{f_1+j\atopwithdelims ()j}^m{f_2\atopwithdelims ()j}^l\lambda ^j. \end{aligned}$$

In this article, we prove certain Beukers-like supercongruences for these generalized Apéry numbers.

     

Temperature dependence of dc photoconductivity in CdTe thin films

The temperature dependence of dc photoconductivity in the measuring range 303–417 K has been studied in CdTe thin films having thicknesst < 4000 Å. The photoactivation energy decreases in dark which is explained on the basis of grain boundary (GB) effect. The current lost to recombination at GB space charge region causes a negative effect on the photosensitivity of the films. A decrease in photosensitivity with increase in temperature is attributed to the reduction of photoexcitation process. It is observed that the minority carrier lifetime varies inversely with light intensity which supports the sublinear relationship of photoconductivity with the intensity of light and thereby confirms the defect-controlled photoconductivity in CdTe thin films     

Measurements of elastic scattering for 7Be, 7Li + 9Be systems and fusion cross sections for 7Li + 9Be system

Elastic scattering angular distributions have been measured for ⁷Be + ⁹Be system at E_lab = 17, 19 and 21 MeV in the angular range θ_cm=26^○–58°, and for ⁷Li + ⁹Be system at E_lab= 15.75, 24 and 30 MeV. An optical model (OM) analysis of these data have been carried out. For the ⁷Li + ⁹Be system fusion cross sections were obtained at E_lab = 15.75, 24 and 30 MeV by measuring the α-evaporation spectra from the compound nucleus at backward angles. The measured α-evaporation spectra were reproduced by the statistical model calculations and fusion cross sections were extracted therefrom. The ratios of the experimental fusion cross sections to the total reaction cross sections (obtained form OM analysis) were found to be rather small. This result suggests that break-up process has a strong influence on fusion process leading to a reduction in fusion cross section.     

CuNi binary alloy catalyst for growth of nitrogen‐doped graphene by low pressure chemical vapor deposition

The CuNi binary alloy can be significant as a catalyst for nitrogen‐doped (N‐doped) graphene growth considering controllable solubility of both carbon and nitrogen atoms. Here, we report for the first time the possibility of synthesizing substitutional N‐doped bilayer graphene on the binary alloy catalyst. Raman spectroscopy, atomic force microscopy and transmission electron microscopy analysis confirm the growth of bilayer and few‐layer graphene domains. X‐ray photoelectron spectroscopy analysis shows the presence of around 5.8 at% of nitrogen. Our finding shows that large N‐doped bilayer graphene domains can be synthesized on the CuNi binary alloy.

     

Compact fiber laser at L-band region using Erbium-doped Zirconia fiber

A compact Erbium-doped fiber laser (EDFL) operating in L-band region is demonstrated using a fabricated Erbium-doped Zirconia fiber (EDZF) for the first time. The fiber is fabricated by combining Zr and Al to achieve the maximum Erbium ion concentration of 4320 wt ppm. By using a fiber Bragg grating (FBG) in a ring configuration, the laser operates at 1579.6 nm with a slope efficiency of 13.6% and the threshold pump power of 25.1 mW. The lasing wavelength is obtained at Bragg wavelength with an output power of 13 dBm and a 3 dB spectral width of 0.02 nm using a piece of 2 m long EDZF in conjunction with 120 mW of 1480 nm pump power.