Computational Investigation of the Electronic and Thermoelectric Properties of Strained Bulk Mg2Si

The purpose of this work was to investigate, by numerical simulation, the effect of isotropic and anisotropic strain on the transport properties of Mg₂Si. Analysis of the effects of temperature and charge-carrier concentration on evolution of the energy gap and on the thermoelectric properties of strained Mg₂Si is also reported in this paper. Gap evolution is highly dependent on the type of strain applied to the structure. The Seebeck coefficient (S) and power factor (PF) are strongly modified; a gain of up to 40% can be obtained for S and up to 100% for PF under specific conditions of strain. In most cases the temperature corresponding to the maximum value of PF was found to shift downward under the effect of strain.     

Towards Understanding the Decomposition/Isomerism Channels of Stratospheric Bromine Species: Ab Initio and Quantum Topology Study

The present study aims at a fundamental understanding of bonding characteristics of the C–Br and O–Br bonds. The target molecular systems are the isomeric CH₃OBr/BrCH₂OH system and their decomposition products. Calculations of geometries and frequencies at different density functional theory (DFT) and Hartree–Fock/Møller–Plesset (HF/MP2) levels have been performed. Results have been assessed and evaluated against those obtained at the coupled cluster single-double (Triplet) (CCSD(T)) level of theory. The characteristics of the C–Br and O–Br bonds have been identified via analysis of the electrostatic potential, natural bond orbital (NBO), and quantum theory of atoms in molecules (QTAIM). Analysis of the electrostatic potential (ESP) maps enabled the quantitative characterization of the Br σ-holes. Its magnitude seems very sensitive to the environment and the charge accumulated in the adjacent centers. Some quantum topological parameters, namely ∇²ρ, ellipticity at bond critical points and the Laplacian bond order, were computed and discussed. The potential energy function for internal rotation has been computed and Fourier transformed to characterize the conformational preferences and origin of the barriers. NBO energetic components for rotation about the C–Br and O–Br bonds as a function of torsion angle have been computed and displayed.     

Effects of nutritional status on serum fetuin-A level

Abstract

Fetuin-A is a glycoprotein structured molecule which is mostly released by the liver. As a multifunctional protein, fetuin-A has positive effects on health such as calcification, cardiovascular diseases and tumor development processes with various mechanisms, whereas it plays a negative role in the processes of obesity, diabetes and fatty liver disease. There are a large number of studies reporting that serum fetuin-A levels are affected by several dietary factors. It is reported in some of these studies that several nutrients increase fetuin-A release, while some others have adverse effects. It is put forward that some nutrients such as dairy products, curcumin, niacin, palmitate, coffee and alcohol consumption decrease fetuin-A level, and dietary omega-3 fatty acids intake may increase fetuin-A concentration. In addition, it is indicated that high blood glucose levels increase hepatic fetuin-A release by activating extracellular signal-regulated kinase 1/2 enzymes and increased plasma free fatty acids do the same effect by increasing NF-_KB activity. Despite these studies in the literature, there is not any review evaluating fetuin-A, chronic diseases and nutrition together. Therefore, in this study, the relationship between serum fetuin levels and some diseases and the effects of nutrients on fetuin A levels were investigated with possible mechanisms.     

Photocatalytic degradation of methylene blue with Co alloyed CdZnS nanoparticles

In our present study, firstly; cadmium zinc sulfide (CdZnS) nanoparticles (NPs) with 1, 2, 5, 10% of Zn concentration were synthesized in aqueous solution by simple chemical co-precipitation method and their photocatalytic activity was investigated using the degradation of methylene blue under visible light in air at room temperature. It was found that CdZnS NPs with 2% of Zn concentration indicates the highest degradation efficiency compare to other Zn concentrations. CdZnS NPs with 2% of Zn concentration was symbolized as CdZnS_1. Later; 0.1, 0.2, 0.5, 1, 5, 10% of cobalt (Co) concentration was separately alloyed on the CdZnS_1 NPs. It was oberved that Co(5%):CdZnS NPs has the highest degradation efficiency. Structure, surface morphology, elemental analysis and optical properties of CdZnS_1 and Co (5%): CdZnS NPs 0were analyzed using X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray and UV–Vis absorption measurements, respectively. The results showed that Co doped CdZnS NPs can be employed as capable materials to ehance the photocatalytic activity.     

Degradation of the antimicrobial triclocarban (TCC) with ozone

Triclocarban (TCC) has been used as an antimicrobial compound for many decades due to its sanitising properties. Recent studies showed that TCC is toxic and causes disruption to the endocrine system. In this work, ozone oxidation of TCC was studied in 70% acetonitrile:30% water solutions. Ozone degraded TCC effectively and the reaction rates increased substantially with ozone gas concentration, pH and temperature. Second-order-reaction kinetics was suitable to describe the chemical reaction. The effect of temperature was described by the Arrhenius equation and the activation energy was found equal to 31.0 kJ/mol. The stoichiometry of the reaction was one and the value of the rate constant at pH 7 was 5 × 10³ M⁻¹ s⁻¹.     

Comparative study on multifunctional behaviour of rare earth manganites with micro and nano grain size

We have investigated electrical and magnetotransport properties of La_0.7Sr_0.3MnO₃ samples with grain size in micro to nanometric regime. The structural parameters obtained by Rietveld refinement of X-ray diffraction data revealed perovskite structure with orthorhombic (Pnma) and rhombohedral (R3C) symmetry for nano and bulk samples respectively. The average particle size was 22 nm and 2 μm for the two representative samples. A metal–insulator transition and substantial increase in electrical resistivity was observed in nanomaterials. An enhanced magnetoresistance observed in nanomaterials samples, makes them more promising for advanced device applications. The magnetization study showed signature of ferromagnetic cluster behavior and higher temperature coefficient of magnetization in nanoparticle samples.     

Inhibitory effects of various essential oils and individual components against extended-spectrum beta-lactamase (ESBL) produced by Klebsiella pneumoniae and their chemical compositions

In the current study, in vitro inhibitory activity of several essential oils obtained from the cultivated plants, Foeniculum vulgare, Mentha piperita and M. spicata, Ocimum basilicum, Origanum majorana, O. onites, O. vulgare, Satureja cuneifolia, and a number of individual essential oil components of terpene and aromatic types were screened against 10 isolated strains of Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) enzyme, which makes this microorganism quite resistant against the antibiotics: trimetoprime-sulfametoksazol, sulbactam-ampicilin, clavulonate-amoxicilin, ceftriaxon, cefepime, imipenem, ceftazidime, tobramicine, gentamisine, ofloxacin, and ciprofloksasin. All of the essential oils and the components exerted a remarkable inhibition ranging between 32 and 64 μg/mL against all of these strains as strong as the references (ampicilin and oflaxocin) inhibiting at 32 μg/mL. Besides, chemical compositions of the essential oils were elucidated by gas chromatography-mass spectrometry (GC-MS). The essential oils and the pure components widely found in essential oils screened herein have shown remarkable inhibition against ESBL-producing K. pneumoniae strains, which leads to the suggestion that they may be used as food preservatives for this purpose. Practical Application: The essential oils obtained from Foeniculum vulgare, Mentha piperita and M. spicata, O.cimum basilicum, Origanum majorana, O. onites, O. vulgare, and Satureja cuneifolia as well as common essential oil components have shown notable inhibitory effects against 10 isolated strains of Klebsiella pneumoniae producing extended-spectrum beta-lactamase (ESBL) enzyme and they might be used as food preservative or ingredient.     

Isotherms and thermodynamics for the sorption of heavy metal ions onto functionalized sporopollenin

Auto-ignition of lubricating oil working in a compressor for an air conditioner is studied experimentally. The adopted lubricating oil is an unknown mixture with multi-components and known to have flash point temperature of 170 °C. First, its auto-ignition temperature is measured 365 °C at atmospheric pressure. The lubricating oil works under high-pressure condition up to 30 atm and it is heated and cooled down repeatedly. Accordingly, auto-ignition temperatures or flammable limits of lubricating oil are required at high pressures with respect to fire safety. Because there is not a standard test method for the purpose, a new ignition-test method is proposed in this study and thereby, auto-ignition temperatures are measured over the pressure range below 30 atm. The measured temperatures range from 215 °C to 255 °C and they strongly depend on pressure of gas mixture consisting of oil vapor, nitrogen, and oxygen. They are close to flash point temperature and the lubricating oil can be hazardous when it works for high-pressure operating condition and abundant air flows into a compressor.