7Li NMR analysis on perovskite structured Li0.15La0.28TaO3

The nanocrystalline perovskite material Li_0.15La_0.28TaO₃ has been synthesized by alkoxide-free Pechini type sol gel method. ⁷Li NMR measurements were carried out using a Bruker Avance 300 spectrometer at 116 MHz over the temperature range 150 to 400 K. Longitudinal spin-lattice relaxation times (T₁) measured by saturation recovery and longitudinal relaxation times in the rotating frame (T_1ρ) measured using the pulse sequence (π/2–spin lock τ acquisition) with lock radio-frequency field υ = 62.5 kHz and the T₂ relaxation time measured by Hahn echo are presented. The static Hahn-echo spectra show two different lithium sites in this perovskite oxide. Further, the relaxation measurements T₁ and T_1ρ show two different types of lithium cations with fast and slow dynamics.     

Influence of protease on dyeing of wool with acid dyes

The application of enzymes in the wool dyeing process is an important research goal in order to reduce the environmental impact and costs of this finishing process. The work has focused on the possibility of reducing the temperature of conventional dyeing, using an enzymatic pretreatment with a neutral protease to improve the diffusion of the dye into the fibers. After the identification of the optimal dyeing process, the study goes on transferring the method to an industrial application. For this reason the influence of a leveling agent added to the dyeing bath was considered and further tests with an industrial dyeing recipe were performed. In order to evaluate possible fiber damage, samples treated with enzyme were observed by scanning electron microscopy (SEM) and analyzed by gel electrophoresis (SDS-PAGE). Moreover, the variation of tensile strength and elongation of dyed samples were determined. In addition, color fastness to domestic laundering, perspiration and rubbing were carried out. Finally, color measurements and fiber section analysis were performed. The results show the possibility, thanks to the pretreatment with the investigated enzyme, to obtain a homogeneous and solid dyeing on fibers maintaining good mechanical properties, already working at 85°C instead of 98°C currently used in industry.      

Impedance spectroscopy and conduction mechanism of multiferroic (Bi0.6K0.4)(Fe0.6Nb0.4)O3

Polycrystalline (Bi_0.6K_0.4) (Fe_0.6Nb_0.4)O₃ material has been prepared using a mixed-oxide route at 950 °C. It was shown by XRD that at room temperature structure of the compound is of single-phase with hexagonal symmetry. Some electrical characteristics (impedance, modulus, conductivity etc.) were studied over a wide frequency (1 kHz–1 MHz) and temperature (25–500 °C) ranges. The Nyquist plot (i.e., imaginary vs real component of complex impedance) of the material exhibit the existence and magnitude of grain interior and grain boundary contributions in the complex electrical parameters of the material depending on frequency, input energy and temperature. The nature of frequency dependence of ac conductivity follows Joncher׳s power law, and dc conductivity follows the Arrhenius behavior. The appearance of P–E hysteresis loop confirms the ferroelectric properties of the material with remnant polarization (2P_r) of 1.027 µC/cm² and coercive field (2E_c) of 16.633 kV/cm. The material shows very weak ferromagnetism at room temperature with remnant magnetization (2M_r) of 0.035 emu/gm and coercive field (2H_c) of 0.211 kOe.     

Novel Triazole Thiole ligand and some of its metal chelates: Synthesis,structure charactertization,thermal behavior in comparison withcomputational caculations andbiological activities

Structural and molecular properties of HL, 4-amino-5-(2,2-dichloro-1-methylcyclopropyl)-4H-1,2,4-triazole-3-thiol toward the transition metal ions namely Fe(III), Co(II) and Ni(II) had been studied using elemental analyses, magnetic, electronic, FT- IR, ¹H-NMR and Thermal analyses (TGA and DTA). The interpretation of thermal decomposition stages had been evaluated. The computations had been done by software of Gaussian 09W package. The geometries of triazole-thiole ligand and its metal chelates were fully optimized using density functional theory B3LYP method. (DFT)/GENECP level by implementing Def2TZVP basis set was used for Fe, Co and Ni-atoms; and basis set 6-311++G (d, p) was used for remainder atoms. There are no symmetry constrains had been applied during geometry optimization. The mixed basis set was selected due to its flexibility. HOMO and LUMO energy values for chelates, chemical hardness and electronegativity had been calculated. NBO calculations had been done at the same level using (NBO 3.1) program involved in the software of Gaussian 09W for measurement qualitatively the intra-molecular delocalization in systems under investigation. The first 15, 85, 65 and 65 low-lying excited states for ligand and Fe, Co and Ni chelates respectively had been calculated within the vertical linear-response. TD-DFT approximation at the same level of theory was used to calculate the electronic absorption spectra of the studied compounds. Their structures are confirmed by successful correlation between experimental and theoretical calculations. The ligand and its metal chelates had been examined against two bacteria such as Gram-positive (Staphylococcus aureus ATTC 12600), GraM–Negative (Escherichia coli ATTC 11775) and two fungus (Aspergillus flavus and Candida albicans) and molecular docking using Auto Dock tools were utilized.     

Efficient detection of CO2 by nanocomposites: Environmental and energy technologies

Nanocomposite materials have received much attention from scientists and engineers interested in the detection and photoreduction of CO₂ compounds. Their interest is due in large part to the unique properties of these materials, including their high degree of photoactivity, thermal stability, high surface area, and malleability. In the present review, we focus on several nanocomposite types used for the detection and photochemical reduction of CO₂: titania-based nanocomposites, chalcogenide-based nanocomposites, LDHs-based nanocomposites, and MOFs-based nanocomposites. More specifically, trends in green synthesis nanocomposites, methods for detecting CO₂ compounds, and the photoreduction of those compounds are summarized in this paper. Several modified approaches to nanocomposite materials have been discussed to achieve optimum results. Generally, we find that the presence of functional active groups, doping metal, and other semiconductor materials act as catalysts, significantly enhancing the photoreduction properties of nano-materials. Moreover, we will also discuss additional challenges, especially in regard to large-scale industrial applications. In our discussion, we will highlight the use of nanocomposite-based materials in the detection and photoreduction of CO₂. It is hoped that our findings will serve as a reference and inspiration for academic researchers and industrial professionals.     

Autotandem Catalysis: Inexpensive and Green Access to Functionalized Ketones by Intermolecular Iron-Catalyzed Amidoalkynylation/Hydration Cascade Reaction via N-Acyliminium Ion Chemistry

Iron-based catalysts were applied in cascade-type reactions for the synthesis of different carbonyl compounds. The reactions proceeded by a new iron-catalyzed cascade of alkynylation/hydration by using both the σ- and π-Lewis acid properties of iron salts. The alkynylation reactions of several endo and exocyclic acetoxylactams were achieved with three different catalysts including FeCl₃ ⋅ 6H₂O, FeCl₃, and Fe(OTf)₃ showing the efficiency of σ-Lewis acidity of iron (III) salts in catalyzing the alkynylation reaction. We also demonstrated that the reaction sequence could be shortened by the direct use of hydroxylactams, leading to an environmentally friendly protocol, avoiding the need to perform unnecessary lengthy steps. A combination of the hard/soft iron Lewis acid properties was then used to implement an unprecedented tandem intermolecular alkynylation/intramolecular hydration sequence allowing expedient access to a new carbonyl structures from trivial materials.     

Critical properties and exchange interactions of the antiferromagnetic tetrahedral spinel

The high-temperature series expansion for the spin correlation functions of the A-spinel lattice has been derived. The development is extended to order 6 in β=1/k_BT with nearest-neighbour (nn) and next-nearest-neighbour (nnn) exchange couplings. The paramagnetic susceptibility and the correlation length are also given.The series is examined via the Padé approximants method and estimates for the transition temperature T_N are obtained for various values of the ratio α=J₂/|J₁|. It is found that the variation of critical temperature is well represented by T(α)=T(0)[1+3.0725α] for values of α in the range −0.2≤α. T(0) is the critical temperature of the nn model.The approach is applied to the experimental results of the particular system A-spinel CoCo₂O₄. The following estimates are obtained for the familiar critical exponents: γ=1.382 and v=0.701.     

Classical univariate calibration and partial least squares for quantitative analysis of brass samples by laser-induced breakdown spectroscopy

In this work we compare the analytical results obtained by traditional calibration curves (CC) and multivariate Partial Least Squares (PLS) algorithm when applied to the LIBS spectra obtained from ten brass samples (nine standards of known composition and one ‘unknown’). Both major (Cu and Zn) and trace (Sn, Pb, Fe) elements in the sample matrix were analyzed. After the analysis, the composition of the ‘unknown’ sample, measured by X-ray Fluorescence (XRF) technique, was revealed. The predicted concentrations of major elements obtained by rapid PLS algorithms are in very good agreement with the nominal concentrations, as well as with those obtained by the more time-consuming CC approach. A discussion about the possible effects leading to discrepancies of the results is reported. The results of this study open encouraging perspectives towards the development of cheap LIBS instrumentation which would be capable, despite the limitations of the experimental apparatus, to perform fast and precise quantitative analysis on complex samples.     

Synthesis,Characterization, and Anti-Diabetic Therapeutic Activity of New Vanadyl(II) Complexes with Orotic Acid and Different Amino Acids Mixed Ligands

Russian Journal of General Chemistry - Mixed ligand vanadyl(II) complexes of orotic acid and six different amino acids (isoleucine, threonine, proline, phenylalanine, lysine, and glutamine) have...     

Photodegradation of Naproxen Using Ag/AgCl–PANI Composite under Solar Light: Transformation Product and Reaction Kinetics

Kinetics and Catalysis - The photocatalytic degradation of organic micropollutant naproxen (NPX) was evaluated under solar light using Ag/AgCl–polyaniline (Ag/AgCl–PANI) photocatalyst....