Kelvin Probe Force Microscopy on Graphene Thin Films for Solar Cell and Biosensing Applications

Graphene, a one atom thick planer sheet of carbon atoms, has attracted much attention in scientific and technological communities due to its remarkable electronic and physical properties. Graphene has been widely studied as an alternative to transparent conducting Indium Tin Oxide (ITO) electrodes in organic photovoltaics fabrication. Graphene platforms have also attracted interest in biological applications. However, large area graphene films are not yet widely commercialized because the fabrication techniques needed to prepare high quality graphene are expensive and non-scalable. More importantly, most of the low cost fabrication techniques require using toxic materials, which are not biocompatible for using graphene in bio-applications. In this work, we have proposed ribonucleic acid (RNA), a nonionic surfactant, for exfoliation of graphite in single and few layered graphene flakes in water solution and the subsequent preparation of transparent and conducting graphene-RNA thin films. A number of pre- and post-deposition treatments were performed to improve the electrical and optical performance of graphene-RNA thin films. We further assembled organic photovoltaics on such graphene electrodes using poly(3-hexyl-thiophene):phenyl-C61-butyric acid methyl ester blended photoactive layers. Such photovoltaic devices exhibited high open circuit voltages compared with the reference ITO-based devices. The origin of open circuit voltage was investigated using Kelvin Probe Force Microscopy (KPFM) in the dark and under light irradiation. In our study, we have also demonstrated the fabrication of photovoltaic devices from cost-effective, water-soluble, and bio-sensitive acridine orange molecules. We investigated the morphology and work function of acridine orange using Atomic Force Microscopy and KPFM. Acridine orange’s ability to generate sufficient amounts of photo carriers was also demonstrated using KPFM under laser irradiation. To this end, the adhesion of eight proteinogenic amino acids, including Arginine, Tryptophan, Histidine, Lysine, Phenylalanine, Alanine, Asparagine, and Aspartic acid, on the graphene samples was studied using KPFM. The adhesion energy was increased in the order of Ala\u3c Asp\u3c Asn\u3c Lys\u3c Phe\u3c His\u3c Trp\u3c Arg. The results were in good agreement with the previous theoretical calculations of the van der Waals contributions for the adsorption energies of different amino acids with the graphene surface

Association between Hypoadiponectinemia and Low Serum Concentrations of Calcium and Vitamin D in Women with Polycystic Ovary Syndrome

Objective. To investigate the possible association of calcium and vitamin D deficiency with hypoadiponectinemia in women with PCOS. Subjects and Methods. In this case-control study, 103 PCOS cases and 103 controls included. The concentrations of calcium, 25-OH-vitamin D (25OHD), adiponectin, insulin, glucose, total cholesterol, HDL-cholesterol, triglyceride (TG), and androgens were measured in fasting blood samples. Results. Adiponectin (8.4 ± 2.7 ng/mL versus 13.6 ± 5 ng/mL in control group, P : 0.00), calcium (2 ± 0.1 mmol/L versus 2.55 ± 0.17 mmol/L in controls, P : 0.00), and 25-OH-Vit D (30 ± 2.99 nmol/L versus 43.7 ± 5.2 nmol/L in control group, P : 0.00) levels were decreased in women with PCOS. Subjects with PCOS had higher concentrations of TG (1.4 ± 0.77 mmol/L versus 1.18 ± 0.75 mmol/L in control group, P : 0.019) and dehydroepiandrosterone sulfate (DHEA-S) (10.7 ± 11 mmol/L versus 9.7 ± 10.4, P : 0.02 in control group). There were significant correlations between adiponectin concentrations with calcium (r : 0.78, P : 0.00) and 25OHD levels (r : 0.82, P : 0.00). The association of hypoadiponectinemia and PCOS was not significant considering 25OHD as a confounding factor. Conclusion. The present findings indicate that the association of hypoadiponectinemia with PCOS is dependent on vitamin D. A possible beneficiary effect of vitamin D on the metabolic parameters in PCOS may be suggested

Effects of garlic (Allium sativum) extract on the expression of receptor for advanced glycation end products and proinflammatory cytokines secretion in peripheral blood mononuclear cells from patients with type 2 diabetes mellitus

Background: Receptor for advanced glycation end products (RAGE) plays a causative role in diabetes. Garlic (Allium sativum) belongs to compounds with anti-glycation activity that can be considered as probable therapeutic approaches in delaying or preventing the onset of diabetes complications. The aim of this study was to evaluate the influence of garlic on the RAGE expression and proinflammatory cytokines secretion in peripheral blood mononuclear cells (PBMCs) from patients with type 2 diabetes mellitus.Materials and Methods: The PBMCs were isolated from 20 patients with fasting blood sugar level above 126 mg/dl and treated with R10 fraction and whole garlic extract in presence or absence of glycated albumin. The expression of RAGE was detected using flow cytometry and the proinflammatory cytokines secretion was evaluated by ELISA.Results: Glycated albumin increased RAGE expression and proinflammatory cytokines secretion. Treatment with whole garlic extract significantly reduced TNF-α and IL-1β secretion and RAGE expression by PBMCs but R10 fraction augmented the proinflammatory cytokines and RAGE expression in absence or presence of glycated albumin.Conclusion: Downregulation of RAGE expression was associated with decreased secretion of IL-1β and TNF-α from PBMCs after treatment with whole garlic, while R10 fraction of garlic significantly augmented RAGE expression and proinflammatory cytokines secretion. These data indicates that modulation of RAGE expression may be one plausible reason for the garlic effects on proinflammatory cytokines secretion

Mathematical programming with LFS functions

Differentiable functions with a locally flat surface (LFS) have been recently introduced and studied in convex optimization. Here we extend this motion in two directions: to non-smooth convex and smooth generalized convex functions. An important feature of these functions is that the Karush-Kuhn-Tucker condition is both necessary and sufficient for optimality. Then we use the properties of linear LFS functions and basic point-to-set topology to study the "inverse" programming problem. In this problem, a feasible, but nonoptimal, point is made optimal by stable perturbations of the parameters. The results are applied to a case study in optimal production planning

800-52'1-0600 Analyt ic Center Cut t ing Plane and Pat h-Following Interior- Point Methods in Convex Programming and

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An Analytic Center Quadratic Cut Method for the Convex Quadratic Feasibility Problem

. We consider a quadratic cut method based on analytic centers for two cases of convex quadratic feasibility problems. In the first case, the convex set is defined by a finite yet large number of convex quadratic inequalities. We extend quadratic cut algorithm of Luo and Sun [3] for solving such problems by placing or translating the quadratic cuts directly through the current approximate center. We show that our algorithm has the same polynomial worst case complexity as theirs [3]. In the second case, the convex set is defined by an infinite number of certain strongly convex quadratic inequalities. We adapt the same quadratic cut method for the first case to the second one. We show that in the second case the quadratic cut algorithm is a fully polynomial approximation scheme. Furthermore, we show that in both cases, at each iteration, the total number of (damped) Newton steps required to update from one approximate analytic center to another is at most O(1). Keywords. Convex quadrati..

Serum ferritin concentration in gestational diabetes mellitus and risk of subsequent development of early postpartum diabetes mellitus.

PURPOSE: To compare the serum ferritin concentrations of normal pregnant women with those having gestational diabetes mellitus (GDM) and to determine the possible role of ferritin in predicting pregnancy outcome and early development of postpartum glucose intolerance and diabetes mellitus. METHOD: This case-control study consisted of 128 pregnant women (64 women with GDM and 64 age-matched healthy pregnant women) seen at a university hospital in Zanjan, Iran. Anthropometric measurements were determined, and serum ferritin, C-reactive protein, insulin, glycosylated hemoglobin (HbA(1c)), and hemoglobin levels were measured. Pregnancy outcomes were recorded in all subjects. In the women with GDM, a diagnostic oral glucose tolerance test was performed eight weeks after delivery. RESULTS: Women with GDM had a higher concentration of serum ferritin (112 ± 28.4 pmol/L in GDM versus 65 ± 16.9 pmol/L in controls, P < 0.001). A positive correlation was found between serum ferritin level and mid-pregnancy fasting plasma glucose and HbA(lc) levels. Although women in the highest quartile of serum ferritin had a greater than two-fold increased risk of GDM, no significant correlation was found between ferritin levels and early postpartum oral glucose tolerance test results. CONCLUSIONS: Elevated serum ferritin concentrations in mid-pregnancy are associated with an increased risk of GDM independent of C-reactive protein and body mass index. Ferritin levels in GDM cannot be used as an indicator to predict subsequent glucose concentration in early postpartum oral glucose tolerance test

A Path-Following Cutting Plane Method for some Monotone Variational Inequalities

The paper considers two cases of variational inequality problems. The first case involves an affine monotone operator over a convex set defined by a separation oracle. An interior-point algorithm that mixes an interior cutting plane method and a short-step path-following method will be presented. Its complexity will be established. The second case involves a nonlinear monotone operator defined over the same type of convex set. An interior-point algorithm which is a combination of a cutting plane method and a long-step path-following method and uses the Jacobian of the operator will be presented. It will be shown that this latter algorithm finds an approximate solution in finite time

Using the Primal Dual Infeasible Newton Method in the Analytic Center Method for Problems Defined by Deep Cutting Planes.

The convergence and the complexity of a primal-dual column generation and cutting plane algorithm from approximate analytic centers for solving convex feasibility problems defined by a &quot;deep cut&quot; separation oracle is studied. The primal-dual infeasible Newton method is used to generate a primal-dual updating direction. The number of recentering steps is O(1) for cuts as deep as half way to the deepest cut, where the deepest cut is a cut that is tangent to the primal-dual variant of Dikin&apos;s ellipsoid. Keywords: Convex feasibility problem, analytic center, column generation, cutting planes, deep cut. AMS subject classification: 90C25, 90C26, 90C60. 1 This research is supported by the Natural Sciences and Engineering Research Council of Canada, grant number OPG0004152, by the FCAR of Quebec and by an Obermann fellowship at the Center for Advanced Studies at the University of Iowa. 1 Introduction The convex feasibility problem defined by a separation oracle is: find an interior poin..

A Path-Following Cutting Plane Method for some Monotone Variational Inequalities

. The paper considers two cases of variational inequality problems. The first case involves an affine monotone operator over a convex set defined by a separation oracle. An interior-point algorithm that mixes an interior cutting plane method and a short-step path-following method will be presented. Its complexity will be established. The second case is an extension of the first and involves a nonlinear monotone operator defined over the same type of convex set. The algorithm for the latter case is different from the former one only in the path-following stage. Keywords. Monotone variational inequalities, interior-point methods, analytic center, cutting planes, potential function. MCS. 90C33, 90C25, 58E35. 1 This research is supported by the Natural Sciences and Engineering Research Council of Canada, grant number OPG0004152 and by the FCAR of Quebec. 2 Faculty of Management, McGill University, 1001 Sherbrooke West, Montreal, Quebec, Canada H3A 1G5 3 Faculty of Management, McGill..