Proteins maintain hydration at high [KCl] concentration regardless of content in acidic amino acids

Proteins of halophilic organisms, which accumulate molar concentrations of KCl in their cytoplasm, have a much higher content in acidic amino acids than proteins of mesophilic organisms. It has been proposed that this excess is necessary to maintain proteins hydrated in an environment with low water activity, either via direct interactions between water and the carboxylate groups of acidic amino acids or via cooperative interactions between acidic amino acids and hydrated cations. Our simulation study of five halophilic proteins and five mesophilic counterparts does not support either possibility. The simulations use the AMBER ff14SB force field with newly optimized Lennard-Jones parameters for the interactions between carboxylate groups and potassium ions. We find that proteins with a larger fraction of acidic amino acids indeed have higher hydration levels, as measured by the concentration of water in their hydration shell and the number of water/protein hydrogen bonds. However, the hydration level of each protein is identical at low (bKCl = 0.15 mol/kg) and high (bKCl = 2 mol/kg) KCl concentrations; excess acidic amino acids are clearly not necessary to maintain proteins hydrated at high salt concentration. It has also been proposed that cooperative interactions between acidic amino acids in halophilic proteins and hydrated cations stabilize the folded protein structure and would lead to slower dynamics of the solvation shell. We find that the translational dynamics of the solvation shell is barely distinguishable between halophilic and mesophilic proteins; if such a cooperative effect exists, it does not have that entropic signature

Optimization of Renewable Energy Businesses under Operational Level Uncertainties through Extensive Sensitivity Analysis and Stochastic Global Optimization

This work presents a decision-making framework for stochastic optimization of renewable energy businesses considering technological uncertainties and risk management. With the help of a global sensitivity analysis based on Sobol’s method, significant uncertain parameters from biochemical reactions are identified. Moreover, two options for selecting sensitive parameters are explored: (1) when all parameters are simultaneously evaluated, and (2) when parameters are separately evaluated based on their kinetic pathway. For both cases, the renewable energy facility is simulated considering uncertainty. To maximize the profitability of the business, a metaheuristic stochastic global optimization technique is incorporated to the framework. This method uses a radial basis function which approximates a computationally expensive objective function and permits intelligent selection of the best operating conditions. To evaluate the efficacy of this framework, a hypothetical multiproduct lignocellulosic biorefinery modeled under operational uncertainty is optimized

A survey of gastrointestinal helminth of stray dogs in Zabol city, southeastern of Iran

Canids are reservoir for some zoonoses helminthic disease. They are one of main public health problem. The aim of this study was to ascertain frequency of gastrointestinal helminthic infection of stray dogs in Zabol city, southeaster of Iran. In this descriptive study, 30 stray dogs were euthanized, intestine was removed by necropsy. Then, the intestines was opened by scalpel and their contents passed through mesh sieve. The helminth were collected. The nematodes were preserved in 70% ethanol with 5% glycerin and cestodes were preserved in 70% ethanol. The cestodes were stained by acetocarmine. The nematodes were cleared by lactophenol. The genus and species of helminth were identified by identification keys. Twenty two (73.3%) of stray dogs had at least one intestinal helminthic infection. Recovered helminth from stray dogs include: Taenia hydatigena (53.3%), Taenia ovis (20%), Taenia multiceps (6.6%), Mesocestoides spp (10%), Toxocara canis (23.3%), Toxocara cati (3.3%). Data showed that the stray dogs in Zabol city harbor some important zoonoses helminth parasite like Toxocara

Combining On-Line Characterization Tools with Modern Software Environments for Optimal Operation of Polymerization Processes

This paper discusses the initial steps towards the formulation and implementation of a generic and flexible model centric framework for integrated simulation, estimation, optimization and feedback control of polymerization processes. For the first time it combines the powerful capabilities of the automatic continuous on-line monitoring of polymerization system (ACOMP), with a modern simulation, estimation and optimization software environment towards an integrated scheme for the optimal operation of polymeric processes. An initial validation of the framework was performed for modelling and optimization using literature data, illustrating the flexibility of the method to apply under different systems and conditions. Subsequently, off-line capabilities of the system were fully tested experimentally for model validations, parameter estimation and process optimization using ACOMP data. Experimental results are provided for free radical solution polymerization of methyl methacrylate

The effect of computer-based tests on nursing students' test anxiety: A quasi-experimental study

Background: Test anxiety often leads to poor academic performance. This study aimed to determine the effect of computer-based tests on nursing students' test anxiety. Methods: This quasi-experimental study was conducted in 2016 on 39 nursing student with anxiety score under 128 on Spielberger's State-Trait Inventory (STAI). They were randomly allocated to computer-based tests (CBT) and paper-based test (PBT) group. Prior to exam, all students completed Sarason's Test Anxiety Scale (TAS). We administered CBT for students in experimental group. Data were analyzed using independent t-test and one-way ANOVA. Results: Students mean test anxiety score was 11.94 and 11.32 in CBT and PBT groups, respectively. 47.4 of students in CBT group and 29.4 of those in PBT group experienced higher test anxiety, while the difference was not significant (p=0.56). Conclusions: Despite, there was no significant difference between anxiety score of two groups; but students' test anxiety score was higher in CBT group. With the current increase in computer-based assessment, educational administrators must be aware of and plan for the possible unfavorable effects of computer assisted testing, such an anxiety. Future studies are needed to evaluate and compare the effect of different type of student testing such as distance testing or CBTs using new information technologies such as laptop, tablet or mobile phone on students' test anxiety and performance. © 2018 Shohreh Kolagari, Mahnaz Modanloo, Reza Rahmati, Zahra Sabzi, Ali Jannati Ataee

A high-dimensional microfluidic approach for selection of aptamers with programmable binding affinities

Aptamers are being applied as affinity reagents in analytical applications owing to their high stability, compact size and amenability to chemical modification. Generating aptamers with different binding affinities is desirable, but systematic evolution of ligands by exponential enrichment (SELEX), the standard for aptamer generation, is unable to quantitatively produce aptamers with desired binding affinities and requires multiple rounds of selection to eliminate false-positive hits. Here we introduce Pro-SELEX, an approach for the rapid discovery of aptamers with precisely defined binding affinities that combines efficient particle display, high-performance microfluidic sorting and high-content bioinformatics. Using the Pro-SELEX workflow, we were able to investigate the binding performance of individual aptamer candidates under different selective pressures in a single round of selection. Using human myeloperoxidase as a target, we demonstrate that aptamers with dissociation constants spanning a 20-fold range of affinities can be identified within one round of Pro-SELEX

Controlling Differentiation of Stem Cells for Developing Personalized Organ-on-Chip Platforms

Organ-on-chip (OOC) platforms have attracted attentions of pharmaceutical companies as powerful tools for screening of existing drugs and development of new drug candidates. OOCs have primarily used human cell lines or primary cells to develop biomimetic tissue models. However, the ability of human stem cells in unlimited self-renewal and differentiation into multiple lineages has made them attractive for OOCs. The microfluidic technology has enabled precise control of stem cell differentiation using soluble factors, biophysical cues, and electromagnetic signals. This study discusses different tissue- and organ-on-chip platforms (i.e., skin, brain, blood-brain barrier, bone marrow, heart, liver, lung, tumor, and vascular), with an emphasis on the critical role of stem cells in the synthesis of complex tissues. This study further recaps the design, fabrication, high-throughput performance, and improved functionality of stem-cell-based OOCs, technical challenges, obstacles against implementing their potential applications, and future perspectives related to different experimental platforms