Electro-Oxidation of p-Silicon in Fluoride-Containing Electrolyte: A Physical Model for the Regime of Negative Differential Resistance

When Si is anodically oxidized in a fluoride containing electrolyte, an oxide layer is grown. Simultaneously, the layer is etched by the fluoride containing electrolyte. The resulting stationary state exhibits a negative slope of the current-voltage characteristics in a certain range of applied voltage. We propose a physical model that reproduces this negative slope. In particular, our model assumes that the oxide layer consists of both partially and fully oxidized Si and that the etch rate depends on the effective degree of oxidation. Finally, we show that our simulations are in good agreement with measurements of the current-voltage characteristics, the oxide layer thickness, the dissolution valence, and the impedance spectra of the electrochemical system.Comment: 19 pages, 13 figures, accepted for publication in EPJ S

Volume changes during active shape fluctuations in cells

Cells modify their volume in response to changes in osmotic pressure but it is usually assumed that other active shape variations do not involve significant volume fluctuations. Here we report experiments demonstrating that water transport in and out of the cell is needed for the formation of blebs, commonly observed protrusions in the plasma membrane driven by cortex contraction. We develop and simulate a model of fluid mediated membrane-cortex deformations and show that a permeable membrane is necessary for bleb formation which is otherwise impaired. Taken together our experimental and theoretical results emphasize the subtle balance between hydrodynamics and elasticity in actively driven cell morphological changes.Comment: Phys. Rev. Lett. in press. 13 pages 4 figures, 9 supplementary figure

Serum testosterone concentration in chloroquinetreated rats: effects of ascorbic acid and alphatocopherol

The effects of ascorbic acid (vitamin C) and alpha-tocopherol (vitamin E) were studied on serum testosterone concentration in chloroquine-treated rats. Thirty five (35) adult male rats weighing 160 - 200 g were divided into seven groups of five (5) rats each. Group I rats served as the control and received 2 ml/kg of normal saline while Group II rats were treated with chloroquine (20 mg/kg). Groups III, IV, V, VI and VII rats were treated with chloroquine (20 mg/kg) and either vitamin C (14.3 or 100 mg/kg) or vitamin E (9.3 mg/kg or 100 mg/kg) or the combination of both. The drugs were administered orally for thirty five (35) days and at the end of the treatment, serum testosterone concentrations were determined. Theresults showed that chloroquine did not cause a significant change in serum testosterone concentration. In addition, the administration of the vitamins with chloroquine also did not cause any significant change in serum testosterone concentration when compared with the control. The results suggest that long-term administration of chloroquine could have no effect on testosterone concentration and the vitamins also could not cause any significant change in testosterone concentration in the presence of chloroquine

Qualitative analysis of a discrete-time phytoplankton–zooplankton model with Holling type-II response and toxicity

[EN]The interaction among phytoplankton and zooplankton is one of the most important processes in ecology. Discrete-time mathematical models are commonly used for describing the dynamical properties of phytoplankton and zooplankton interaction with nonoverlapping generations. In such type of generations a new age group swaps the older group after regular intervals of time. Keeping in observation the dynamical reliability for continuous-time mathematical models, we convert a continuous-time phytoplankton–zooplankton model into its discrete-time counterpart by applying a dynamically consistent nonstandard difference scheme. Moreover, we discuss boundedness conditions for every solution and prove the existence of a unique positive equilibrium point. We discuss the local stability of obtained system about all its equilibrium points and show the existence of Neimark–Sacker bifurcation about unique positive equilibrium under some mathematical conditions. To control the Neimark–Sacker bifurcation, we apply a generalized hybrid control technique. For explanation of our theoretical results and to compare the dynamics of obtained discrete-time model with its continuous counterpart, we provide some motivating numerical examples. Moreover, from numerical study we can see that the obtained system and its continuous-time counterpart are stable for the same values of parameters, and they are unstable for the same parametric values. Hence the dynamical consistency of our obtained system can be seen from numerical study. Finally, we compare the modified hybrid method with old hybrid method at the end of the paper

A Dynamically Consistent Nonstandard Difference Scheme for a Discrete-Time Immunogenic Tumors Model

This manuscript deals with the qualitative study of certain properties of an immunogenic tumors model. Mainly, we obtain a dynamically consistent discrete-time immunogenic tumors model using a nonstandard difference scheme. The existence of fixed points and their stability are discussed. It is shown that a continuous system experiences Hopf bifurcation at one and only one positive fixed point, whereas its discrete-time counterpart experiences Neimark–Sacker bifurcation at one and only one positive fixed point. It is shown that there is no chance of period-doubling bifurcation in our discrete-time system. Additionally, numerical simulations are carried out in support of our theoretical discussion.Spanish Government and European Commission, Grant RTI2018-094336-B-I00 (MCIU/AEI/FEDER, UE); Basque Government, Grant IT1207-19

Absolute risk and risk factors for stroke mortality in patients with end stage kidney disease (ESKD): population-based cohort study using data linkage

INTRODUCTION: People with end-stage kidney disease (ESKD) have up to 30-fold higher risk of stroke than the general population. OBJECTIVE: To determine risk factors associated with stroke death in the ESKD population. METHODS: We identified all patients with incident ESKD in Australia (1980-2013) and New Zealand (1988-2012) from the Australian and New Zealand Dialysis and Transplant Registry (ANZDATA) registry. We ascertained underlying cause of death from data linkage with national death registries and risk factors from ANZDATA. Using a competing risks multivariable regression model, we estimated cumulative incidence of stroke and non-stroke deaths, and risk factors for stroke deaths (adjusted sub-HR, SHR). RESULTS: We included 60 823 people with ESKD. There were 941 stroke deaths and 33 377 non-stroke deaths during 381 874 person-years of follow-up. Overall, the cumulative incidence of stroke death was 0.9% and non-stroke death was 36.8% 5 years after starting ESKD treatment. The risk of stroke death was higher at older ages (SHR 1.92, 95% CI 1.45 to 2.55), in females (SHR 1.41, 95% CI 1.21 to 1.64), in people with cerebrovascular disease (SHR 2.39, 95% CI 1.99 to 2.87), with ESKD caused by hypertensive/renovascular disease (SHR 1.39, 95% CI 1.09 to 1.78) or polycystic kidney disease (SHR 1.38, 95% CI 1.00 to 1.90), with earlier year of ESKD treatment initiation (SHR 1.93, 95% CI 1.56 to 2.39) and receiving dialysis (transplant vs haemodialysis SHR 0.27, 95% CI 0.09 to 0.84). CONCLUSION: Patients with ESKD with higher risk of stroke death are older, women, with cerebrovascular disease, with hypertensive/renovascular or polycystic kidney disease cause of ESKD, with earlier year of ESKD treatment and receiving dialysis. These groups may benefit from targeted stroke prevention interventions

KARAKTERISTIK KEFIR SUSU SAPI DENGAN INOKULUM RAGI TAPE

Kefir is a fermented milk product that has the typical flavours (acids and alcohol) and its processed by a number of microbes which include lactic acid bacteria (LAB) and yeasts.The aims of this study were to know the character of the population of lactic acid bacteria (LAB), a population of yeasts, and chemical characters among others total acid, pH and alcohol levels in kefir milk with inoculum ragi tape. The population of LAB and the population of yeast were calculated with the method of calculation of Total Plate Count. The levels of total acid titration method were determined by the acid. Acidity was measured using a pH meter and alcohol levels were determined by the method of Conway Micro Diffusion. The results showed that the number of LAB has increased to 24 hour fermentations of 9.01 log cells/ml (1,1x109 cells/ml), then the number of cells did not change much until the fermentation time was 48 hours and 72 hours of fermentation on the decline of 8.07 log cells /ml (1,2x108 cells/ml) while the yeast experiences increased from 6 hours to 24 hours, then the amount of yeast did not much change from the 24 to 72 hours of the highest number of yeasts during fermentation 48 hours an amount of 6.12 log cells /ml (1,3x106 cells/ml) and the amount of yeasts did not decline at the time of 72 hours. Total acid continued to experience increased with the number of 0.38-1.24%, pH continued to decline from 6,47-4.27 and alcohol levels continued to experience increased with the number of 0.05-0.38% b/v. Keywords: Inoculum, Kefir Milk, Lactic Acid Bacteria, Ragi Tape, Yeas

Blood eosinophils as a biomarker of future COPD exacerbation risk:pooled data from 11 clinical trials

Background Chronic obstructive pulmonary disease (COPD) is characterised by progressive airflow limitation and chronic inflammation. Predicting exacerbations of COPD, which contribute to disease progression, is important to guide preventative treatment and improve outcomes. Blood eosinophils are a biomarker for patient responsiveness to inhaled corticosteroids (ICS); however, their effectiveness as a predictive biomarker for COPD exacerbations is unclear. Methods This post hoc analysis pooled data from 11 Boehringer Ingelheim-sponsored Phase III and IV randomised COPD studies with similar methodologies. Exacerbation data were collected from these studies, excluding patients from the ICS withdrawal arm of the WISDOM® study. Patients were grouped according to their baseline blood eosinophil count, baseline ICS use and number of exacerbations in the year prior to each study. Results Exacerbation rate data and baseline eosinophil count were available for 22,125 patients; 45.6% presented with a baseline blood eosinophil count of ≤ 150 cells/μL, 34.3% with 150–300 cells/μL and 20.1% with > 300 cells/μL. The lowest exacerbation rates were observed in patients with ≤ 150 cells/μL, with small increases in exacerbation rate observed with increasing eosinophil count. When stratified by exacerbation history, the annual rate of exacerbations for patients with 0 exacerbations in the previous year increased in line with increasing eosinophil counts (0.38 for ≤ 150 cells/μL, 0.39 for 150–300 cells/μL and 0.44 for > 300 cells/μL respectively). A similar trend was identified for patients with one exacerbation in the previous year, 0.62, 0.66 and 0.67 respectively. For patients with ≥ 2 exacerbations, exacerbation rates fluctuated between 1.02 (≤ 150 cells/μL) to 1.10 (150–300 cells/μL) and 1.07 (> 300 cells/μL). Higher exacerbation rates were noted in patients treated with ICS at baseline (range 0.75 to 0.82 with increasing eosinophil count) compared with patients not on ICS (range 0.45 to 0.49). Conclusion We found no clinically important relationship between baseline blood eosinophil count and exacerbation rate. Hence, the current analysis does not support the use of blood eosinophils to predict exacerbation risk; however, previous exacerbation history was found to be a more reliable predictor of future exacerbations. Trial registration ClinicalTrials.gov Identifiers: NCT00168844, NCT00168831, NCT00387088, NCT00782210, NCT00782509, NCT00793624, NCT00796653, NCT01431274, NCT01431287, NCT02296138 and NCT00975195

Short day photoperiod protects against acetaminophen-induced heptotoxicity in rats

This study investigated the effect of different photoperiods on acetaminophen-induced hepatotoxicity in rats. Twenty four adult male rats (average weight = 160±7g) were conditioned to different photoperiod regimens for 6 weeks. At the end of the 6-week period, rats exposed to normal, short and long photoperiods received oral acetaminophen (2g/kg body weight) while in the control group, exposed to normal photoperiod, received oral saline. Rats were sacrificed 24 h after acetaminophen administration by cervical dislocation and blood was collected by cardiac puncture for the estimation of liver enzymes activities. Liver tissues were excised and homogenized for estimation of liver malondialdehyde (MDA) concentration. Elevation of serum levels of alanine and aspartate transaminases and alkaline phosphatase caused by acetaminophen intoxication were not affected in rats subjected to long photoperiod while these parameters were significantly (P<0.05) reduced in rats subjected to short photoperiod. However, alteration of photoperiod resulted in significantly (P<0.05) lower serum gamma glutamate transpeptidase and total protein in acetaminophentreated rats. All groups of rats had similar serum albumin while serum malondialdehyde concentration was significantly lower in rats subjected to short photoperiod. This study revealed the protective effects of short photoperiod against acetaminophen-induced hepatotoxicity and lipid peroxidation in rats.Published onlin