Exploring the possibility of enhancing the figure-of-merit ( >> 2) of Na0.74_{0.74}CoO2_{2}: A combined experimental and theoretical study

Search of new thermoelectric (TE) materials with high \textit{figure-of-merit} (ZT) is always inspired the researcher in TE field. Here, we present a combined experimental and theoretical study of TE properties of Na$_{0.74}$CoO$_{2}$ compound in high-temperature region. The experimental Seebeck coefficient (S) is found to vary from 64 to 118 $\mu$V/K in the temperature range $300-620$ K. The positive values of S are indicating the dominating p-type behaviour of the compound. The observed value of thermal conductivity ($\kappa$) is $\sim$ 2.2 W/m-K at 300 K. In the temperature region $300-430$ K, the value of $\kappa$ increases up to $\sim$ 2.6 W/m-K and then decreases slowly till 620 K with the corresponding value of $\sim$ 2.4 W/m-K. We have also carried out the theoretical calculations and the best matching between experimental and calculated values of transport properties are observed in spin-polarized calculation within DFT+\textit{U} by chosen \textit{U} = 4 eV. The maximum calculated value of ZT is found to be $\sim$ 0.67 at 1200 K for p-type conduction. Our computational study suggests that the possibility of n-type behaviour of the compound which can lead to a large value of ZT at higher temperature region. Electron doping of $\sim$ 5.1$\times$10$^{20}$ cm$^{-3}$ is expected to give rise the high ZT value of $\sim$ 2.7 at 1200 K. Using these temperature-dependent ZT values, we have calculated the maximum possible values of efficiency ($\eta$) of thermoelectric generator (TEG) made by p and n-type Na$_{0.74}$CoO$_{2}$. The present study suggests that one can get the efficiency of a TE cell as high as $\sim$ 11$\%$ when the cold and hot end temperature are fixed at 300 K and 1200 K, respectively. Such high values of ZT and efficiency suggest that Na$_{0.74}$CoO$_{2}$ can be used as a potential candidate for high-temperature TE applications

Handwritten Digit Recognition Using Machine Learning Algorithms

Handwritten character recognition is one of the practically important issues in pattern recognition applications. The applications of digit recognition includes in postal mail sorting, bank check processing, form data entry, etc. The heart of the problem lies within the ability to develop an efficient algorithm that can recognize hand written digits and which is submitted by users by the way of a scanner, tablet, and other digital devices. This paper presents an approach to off-line handwritten digit recognition based on different machine learning technique. The main objective of this paper is to ensure effective and reliable approaches for recognition of handwritten digits. Several machines learning algorithm namely, Multilayer Perceptron, Support Vector Machine, NaFDA5; Bayes, Bayes Net, Random Forest, J48 and Random Tree has been used for the recognition of digits using WEKA. The result of this paper shows that highest 90.37% accuracy has been obtained for Multilayer Perceptron

Spontaneous breaking of time reversal symmetry in strongly interacting two dimensional electron layers in silicon and germanium

We report experimental evidence of a remarkable spontaneous time reversal symmetry breaking in two dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P $\delta-$layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two dimensional electrons are confined to narrow half-filled impurity bands

Mitochondrial fusion and Bid-mediated mitochondrial apoptosis are perturbed by alcohol with distinct dependence on its metabolism

Environmental stressors like ethanol (EtOH) commonly target mitochondria to influence the cell’s fate. Recent literature supports that chronic EtOH exposure suppresses mitochondrial dynamics, central to quality control, and sensitizes mitochondrial permeability transition pore opening to promote cell death. EtOH-induced tissue injury is primarily attributed to its toxic metabolic products but alcoholism also impairs tissues that poorly metabolize EtOH. We embarked on studies to determine the respective roles of EtOH and its metabolites in mitochondrial fusion and tBid-induced mitochondrial apoptosis. We used HepG2 cells that do not metabolize EtOH and its engineered clone that expresses EtOH-metabolizing Cytochrome P450 E2 and alcohol dehydrogenase (VL-17A cells). We found that fusion impairment by prolonged EtOH exposure was prominent in VL-17A cells, probably owing to reactive oxygen species increase in the mitochondrial matrix. There was no change in fusion protein abundance, mitochondrial membrane potential or Ca2+ uptake. By contrast, prolonged EtOH exposure promoted tBid-induced outer mitochondrial membrane permeabilization and cell death only in HepG2 cells, owing to enhanced Bak oligomerization. Thus, mitochondrial fusion inhibition by EtOH is dependent on its metabolites, whereas sensitization to tBid-induced death is mediated by EtOH itself. This difference is of pathophysiological relevance because of the tissue-specific differences in EtOH metabolism. © 2018, The Author(s)

The frequency of occurrence and nature of recombinant feline leukemia viruses in the induction of multicentric lymphoma by infection of the domestic cat with FeLV-945

AbstractDuring feline leukemia virus (FeLV) infection in the domestic cat, viruses with a novel envelope gene arise by recombination between endogenous FeLV-related elements and the exogenous infecting species. These recombinant viruses (FeLV-B) are of uncertain disease association, but have been linked to the induction of thymic lymphoma. To assess the role of FeLV-B in the induction of multicentric lymphoma and other non-T-cell disease, the frequency of occurrence and nature of FeLV-B were examined in diseased tissues from a large collection of FeLV-infected animals. Diseased tissues were examined by Southern blot and PCR amplification to detect the presence of FeLV-B. Further analysis was performed to establish the recombination junctions and infectivity of FeLV-B in diseased tissues. The results confirmed the frequent association of FeLV-B with thymic lymphoma but showed infrequent generation, low levels and lack of infectivity of FeLV-B in non-T-cell diseases including multicentric lymphoma

Prevalence and severity of depression among undergraduate students in Karachi, Pakistan: a cross sectional study

Purpose: To highlight the prevalence and severity of depression among undergraduate students in public and private universities in Karachi, Pakistan.Methods: In this cross-sectional study a total of 408 undergraduate students from both public and private universities in Karachi, Pakistan completed Zung Self-Rating Depression Scale (SDS) questionnaire to appraise the presence and extent of depression among the participants. Their sociodemographic characteristics such as age, gender and course of study as well as drug use data were also collected and analyzed.Results: Depression prevalence was 53.43 % (38.07 % for males and 61.00 % for females). A significant disparity in the prevalence of depression across ethnicity was observed. Less than 50 % (n = 163) of the students were satisfied with their duration of degree course work while 111 (27.20 %) participants were not sure about this. The intensity of depression increased with declining satisfaction level (Gamma = 0.264, p = 0.001) which affected the performance and results of students during their studies. A majority of the participants (89 %, n = 358) of our study have never used medicines to alter their mood.Conclusion: The findings of this study highlight the importance of understanding the unique strains and mental health effect of university education on undergraduate students, especially female students.Keywords: Depression, Undergraduate students, Mood alteration, Zung self-rating depression scale (SDS), Mental health, Risk assessmen

Hypertension and Diabetes as a risk factor for dementia: a cross sectional study

Background: A relation between possible cardiovascular risk factors (hypertension and diabetes) and dementia has been studied in the past and an association has been documented, in spite of some studies pointing to the contrary. Our purpose is to analyze the relation between these risk factors and dementia and add some information to the existing concept and will try to conceptualize the pathogenesis of dementia.Methods: This was a cross sectional study. Patients were recruited from amongst those presenting to our department by convenient consecutive sampling method after taking consent. Five hundred patients of different types of dementia were enrolled. Hypertension was diagnosed using JNC7 criteria. World health organization (WHO) diagnostic criteria were used to diagnose diabetes mellitus. The open Epi software version 3 was used to find the absolute values after preparing 2×2 table. Continuous quantitative data were analyzed using chi square test. Odds ratio and Risk ratio were also calculated. For all statistical tests, a p Value less than 0.05 was taken to indicate significance.Results: Study provides the strong positive association of hypertension (HTN) and diabetes mellitus (DM) with vascular dementia (VaD) but the relationship of these risk factors were not positively correlated with other dementia. Conclusions: Positive association of these risk factors with vascular dementia were found but not with the other types of dementia