Effects of heat treatment on the atomic structure and surface energy of rutile and anatase TiO2 nanoparticles under vacuum and water environments

Nanomaterials have become a widely used group of materials in many chemical engineering applications owing to their ability to provide an enhanced level of functional properties compared to their crystalline and bulk counterparts. Here we report fundamental level advancements on how the anatase and rutile phase of TiO2 nanoparticles chemo-thermally respond between room temperature and the melting temperature under both vacuum and water environments. The current study is based on using molecular dynamics (MD) simulations. We present results on the equilibrium crystal morphology of these phases, structural and surface energy of TiO2 nanoparticles in the size range of 2-6 nm under different temperatures. Thermodynamic and structural properties, in the form of potential energy and Radial Distribution Functions (RDF’s) respectively, are calculated for both forms of TiO2 nanoparticles. The temperature associated with the melting transition increased with an increase in the particle size in both the phases. The potential energy change associated with the melting transition for anatase was seen to be less than that for rutile nanoparticles. Also the temperature at which the RDF’s began to stretch and broaden was observed to be lower for the case of anatase than rutile, suggesting that rutile attains the most thermal stable phase for the nano particle sizes considered in this study. Structural changes in anatase and rutile nanoparticles under different temperatures revealed that non-spherical (rod-like) rutile nanoparticles tend to be thermodynamically more stable. Surface energy influences the shape of TiO2 nanoparticles at different temperatures. The increase in the surface energy of nanoparticles under vacuum when compared with that of water environment is higher for the anatase phase than the rutile phase of nanoparticle sizes studied here. The fundamental level simulation results reported here provide a strong platform for potentially accounting for the effects of atomic-scale phase characteristics of TiO2 nanoparticles and surface energy under different temperature fields in nano processing applications and related multi-scale modelling approaches in future

Comparative Study of the Protective Effect of Granulated Sugar and Garri Meal on Petroleum-induced Changes of Lipid Profiles in Albino Rats (Rattusnorvegicus)

Crude oil contaminated diet has been reported to induced changes in lipid profile of rats. In this study, 60 albino rats in 6 groups were fed with crude oil contaminated sugar-garri diets at varied concentrations to monitor petroleum-induce lipid profile changes using standard methods. The lipid profiles estimated were total cholesterols, triglycerides, high density lipoprotein cholesterol and Low density lipoproteincholesterol.The data showed that, the levels of total cholesterol (Mmol/l) increased from 2.89+0.08 in sugar fed rats compared with 3.05+0.12 in Gari fed rats. The concentration of triglycerides(Mmol/l) reduced from 1.10+0.51 in sugar fed rats to 1.06 + 0.03 in Gari fed rats while the high density lipoprotein cholesterol(Mmol/l) concentration of 2. 01+0.08 was significantly higher than 1.89 + 0.03 in Gari fed rats (P<0.05).There was no significant difference in Low density lipoprotein cholesterol (Mmol/l) concentrations of 0.68+0.11 in sugar fed rats compared with 0.83 + 0.10 in Gari fed rats. The effect of pre-treatment of the diet with sugar reduced petroleum-induce changes in lipid profile than gari during the exposure of the albino rats to the petroleum diet suggesting that sugarcould possibly ameliorate petroleum-induce changes in lipid profile as shown by the significantlowering of the cholesterol and Low density lipoprotein cholesterol than gari in albino rats. Keywords: lipid, Petroleum, Sugar, Gari, Cassava, Change

A Cross-Sectional Characterization of Insulin Resistance by Phenotype and Insulin Clamp in East Asian Americans with Type 1 and Type 2 Diabetes

Classic features of type 1 and type 2 diabetes may not apply in Asian Americans, due to shared absence of common HLA DR-DQ genotype, low prevalence of positive anti-islet antibodies and low BMI in both types of diabetes. Our objective was to characterize diabetic phenotypes in Asian Americans by clamp and clinical features.This was a cross-sectional study conducted in a referral center. Thirty East young Asian American adult volunteers (27.6±5.5 years) with type 1, type 2 diabetes or controls underwent hyperinsulinemic euglycemic clamp to assess insulin resistance and DEXA to assess adiposity.Gender, BMI, waist/hip ratio, leptin, LDL, anti-GAD, anti-IA2 antibodies and C-reactive protein were similar among three groups. Serum C-peptide, adiponectin, free fatty acid, HDL concentrations and truncal fat by DEXA, were different between diabetic groups. Glucose disposal rate by clamp was lowest in type 2 diabetes, followed by type 1 diabetes and controls (5.43±2.70, 7.62±2.59, 8.61±2.37 mg/min/kg, respectively, p = 0.001). Free fatty acid concentration universally plummeted during steady state of the clamp procedure regardless of diabetes types in all three groups. Adipocyte fatty acid binding protein in the entire cohort (r = -0.625, p = 0.04) and controls (r = -0.869, p = 0.046) correlated best with insulin resistance, independent of BMI.Type 2 diabetes in Asian Americans was associated with insulin resistance despite having low BMI as type 1 diabetes, suggesting a potential role for targeting insulin resistance apart from weight loss. Adipocyte fatty acid binding protein, strongly associated with insulin resistance, independent of adiposity in the young Asian American population, may potentially serve as a biomarker to identify at-risk individuals. Larger studies are needed to confirm this finding

Who are 'informal health providers' and what do they do? : perspectives from medical anthropology

This paper explores gaps and limitations in the conceptualisation, methodology and policy implications of debates about informal health care providers by examining a cross section of empirical studies. Drawing on a tradition of critical medical anthropology, we argue that existing debates hinge on a particular understanding of what constitutes appropriate knowledge and on particular expectations of how economic actors in the medical marketplace will behave. Keywords: informal providers; markets; medicine vendors; access; quality; expertise

Structures and orientation-dependent interaction forces of titania nanowires using molecular dynamics simulations

Engineering nano wires to develop new products and processes is highly topical due to their ability to provide highly enhanced physical, chemical, mechanical, thermal and electrical properties. In this work, using molecular dynamics simulations, we report fundamental information, about the structural and thermodynamic properties of individual anatase titania (TiO2) nanowires with cross-sectional diameters between 2 and 6 nm, and aspect ratio (Length: Diameter) of 6:1 at temperatures ranging from 300 to 3000 K. Estimates of the melting-transition temperature of the nanowires are between 2000 and 2500 K. The melting transition temperature predicted from the radial distribution functions (RDFs) shows strong agreement with those predicted from the total energy profiles. Overall, the transition temperature is in reasonable agreement with melting points predicted from experiments and simulations reported in the literature for spherical nanoparticles of similar sizes. Hence, the melting-transition temperature of TiO2 nanowires modelled here can be considered as shape independent. Furthermore, for the first time based on MD simulations, interaction forces between two nanowires are reported at ambient temperature (300 K) for different orientations: parallel, perpendicular, and end-to-end. It is observed that end-to-end orientations manifested the strongest attraction forces, while the parallel and perpendicular orientations, displayed weaker attractions. The results reported here could form a foundation in future multiscale modelling studies of the structured titania nanowire assemblies, depending on the inter-wire interaction forces

Personality traits and mental disorders

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