Simulation Analysis of the Homogenisation Process in Glass Melting through Agitation and Diffusion Processes

Homogenisation in glass melts was investigated in a simulation analysis in which the behaviour of one-dimensional models was calculated with a computer, the concentration profile being simulated by a series of numerical values. The roles of diffusion and agitation in the homogenistaion process in glass melts were discussed. It can be concluded that there is an appropriate combination of diffusion and agitation processes which will result in a desired homogenisation when the levels of intensity and scale of heterogeneity in the glass melts and in finished product are given

Kinetics of Soot Formation in a Flow System Simulating the Lower Part of a Laminar Diffusion Flame

The conversion of fuel hydrocarbons into soot in a flow system simulating the lower part of a diffusion flame was investigated. The soot formation was assumed to consist of the decomposition of the fuel into fragment hydrocarbons, and the polymerization of the fragment hydrocarbons into pre-soot hydrocarbons. The pre-soot hydrocarbons are polycyclic hydrocarbons which form soot particles by further polymerization and condensation. These reaction processes were formulated by a set of differential equations on assuming the reactions are first order and reversible. The rate constants of the reactions and equilibrium constants between hydrocarbons were estimated. The rate constant of the decomposition ranged 7 to 50 sec⁻¹, and increased with increases in the reaction temperature and in addition of oxygen. The rate constant of the polymerization was approximately zero at a reaction temperature of 840°C, and increased with an increase in temperature. It increased with addition of oxygen to a maximum value of 2.8 sec⁻¹ at an oxygen ratio of 0.05 and then decreased, at 955°C. The addition of oxygen had little effect on the equilibrium constants which decrease with an increase in temperature i.e. the reverse reactions can be neglected at high temperatures. The equilibrium constant between fuel and fragment hydtocarbons was 0.5 at 840°C and nearly zero at 955°C. The equilibrium constant between fragment and pre-soot hydrocarbons was 4.0 at 905°C and 1.0 at 955°C

Rate of Volatilization of a Volatile Constituent from Surface of Glass Melts Containing Lead Oxide

A thermal balance technique has been used to study the kinetics of volatilization of a volatile constituent from the surface of glass melts containing lead oxide for extended periods of time in the temperature range 1100° to 1500°C. Distributions of density and refractive index of the glass after heat-treating at 1200-1300°C were also determined

Volatilization of Volatile Constituent from Lead-glass Melts

The kinetics of volatilization of a volatile constituent from the surface of glass melts containing lead oxide for the temperature range of 1100° to 1500°C have been studied with a thermal balance. From the results obtained, it was concluded that both the evaporation-rate coefficient at the surface of the glass melts and the diffusion coefficient of the volatile constituent in the glass melts are controlling factors of the overall rate of volatilization in the system

On the Rate of Combustion of Coke Briquettes in the Fuel Bed

The results of this investigation may be summarized as follows : (1) A quantitative formulation of the reaction rate of coke upon air in the packed bed has been presented under the conditions, under which both diffusion and chemical reaction may affect the reaction rate. (2) By using the theoretical formulas for the rate of reactions, C+O₂→CO₂ and CO₂+ C→2CO, we could calculate the percentages of CO₂, CO and O₂ in the packed bed. Comparing the calculated values with the experimental results, we found the agreement satisfactory

Protective Action of Neurotrophic Factors and Estrogen against Oxidative Stress-Mediated Neurodegeneration

Oxidative stress is involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. Low levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important for maintenance of neuronal function, though elevated levels lead to neuronal cell death. A complex series of events including excitotoxicity, Ca2+ overload, and mitochondrial dysfunction contributes to oxidative stress-mediated neurodegeneration. As expected, many antioxidants like phytochemicals and vitamins are known to reduce oxidative toxicity. Additionally, growing evidence indicates that neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and estrogens significantly prevent neuronal damage caused by oxidative stress. Here, we review and discuss recent studies addressing the protective mechanisms of neurotrophic factors and estrogen within this system

The Arabic Version of the Cohen Perceived Stress Scale: Factorial Validity and Measurement Invariance

University students experience high levels of stress due to university transition, academic commitments, and financial matters. Higher stress perceptions along with limited coping resources endanger mental health for a considerable number of students and may ruin their performance. The current study evaluated the psychometric properties of the Cohen Perceived Stress Scale (10 items), PSS-10, in a sample of 379 female Emeriti students. Exploratory factor analysis resulted in two factors with eigenvalues of 3.88 and 1.19, which explained 60.6% of the variance. Confirmatory factor analysis revealed good model fits of two correlated factors (Comparative Fit Index (CFI) = 0.962, Tucker-Lewis Index (TLI) = 0.950, standardized root-mean-square residual (SRMR) = 0.0479, and root mean-square error of approximation (RMSEA) = 0.067). Internal consistency of the PSS-10 and its positive and negative subscales was acceptable (coefficient α = 0.67, 0.79, and 0.86, respectively). Multigroup analysis revealed that the PSS-10 holds invariance across different groups of age, marital status, and financial status (average monthly expenditure). Convergent and concurrent validity tests signify the importance of considering scores of subscales of the PSS-10 along with its total score

Changes of Myelin Organization in Patients with Alzheimer’s Disease Shown by q-Space Myelin Map Imaging

Background: Recent studies detected the aberrant myelination of the central nervous system (CNS) in Alzheimer’s disease (AD). Here, we compared the change of myelination between patients with AD and controls by a novel magnetic resonance imaging modality, “q-space myelin map (MM) imaging.” Methods: Twenty patients with AD and 18 healthy subjects underwent MM imaging. We compared the MM metric between the 2 groups and examined the relationships between the metric and the clinical symptoms of AD. Results: AD patients showed a significant reduction of MM metric in the hippocampus, insula, precuneus, and anterior cingulate regions. There was also a significant negative correlation between the duration of illness and the MM metric in the temporoparietal region. Conclusion: Our findings suggest that MM imaging could be a clinically proper modality to estimate the myelination changes in AD patients

Association study of the vesicular monoamine transporter 1 (VMAT1) gene with schizophrenia in a Japanese population

BACKGROUND: Vesicular monoamine transporters (VMATs) mediate accumulation of monoamines such as serotonin, dopamine, adrenaline, and noradrenaline from the cytoplasm into storage organelles. The VMAT1 (alternatively solute carrier family 18: SLC18A1) regulates such biogenic amines in neuroendocrine systems. The VMAT1 gene maps to chromosome 8p21.3, a locus with strong evidence of linkage with schizophrenia. A recent study reported that a non-synonymous single nucleotide polymorphism (SNP) of the gene (Pro4Thr) was associated with schizophrenia. METHODS: We attempted to replicate this finding in a Japanese sample of 354 schizophrenics and 365 controls. In addition, we examined 3 other non-synonymous SNPs (Thr98Ser, Thr136Ile, and Val392Leu). Genotyping was performed by the TaqMan allelic discrimination assay. RESULTS: There was no significant difference in genotype or allele distribution of the three SNPs of Pro4Thr, Thr136Ile, or Val392Leu between patients and controls. There was, however, a significant difference in genotype and allele distributions for the Thr98Ser polymorphism between the two groups (P = 0.01 for genotype and allele). When sexes were examined separately, significant differences were observed in females (P = 0.006 for genotype, P = 0.003 for allele), but not in males. The Thr98 allele was more common in female patients than in female controls (odds ratio 1.69, 95% CI 1.19–2.40, P = 0.003). Haplotype-based analyses also provided evidence for a significant association in females. CONCLUSION: We failed to replicate the previously reported association of Pro4Thr of the VMAT1 gene with schizophrenia. However, we obtained evidence for a possible role of the Thr98Ser in giving susceptibility to schizophrenia in women