Heat acclimation and the role of RpoS in prolonged heat shock of Escherichia coli O157

Escherichia coli, a commensal mesophile that primarily inhabits the gastro-intestinal tract, responds to temperature up-shifts with transient expression of stress-response proteins. The goal of this study was to identify adaptive proteins of E. coli O157 crucial for growth resumption of this human pathogen after heat shock, with specific focus on the role of the RpoS sigma factor. Using the comparative proteomic analysis of hyper-thermally acclimatized wild-type strain B-1 and rpoS-mutant strain SV521, we identified 39 proteins that underwent significantly-different induction upon temperature shock at 45°C or rpoS mutation. All identified proteins of the heat post-acclimation stimulon fell into two large sub-groups: (i) stress proteins, including molecular chaperons, proteases, DNA/RNA stabilizing enzymes, and anti-oxidant proteins, and (ii) housekeeping proteins. It was found that in the heat stress stimulon RpoS has significantly (P=0.012) limited control over the key stress proteins involved in translation, translational elongation, protein folding and refolding. However, RpoS showed a significant (P=0.035) control over the cellular metabolic processes that included NADPH regeneration, pentose-phosphate shunt, nicotinamide nucleotide and NADP metabolic processes, reflecting its specific importance in promoting resource utilization (energy, protein synthesis etc.) during proliferation of hyperthermally-adapted cells. Pathogenic strains, like E. coli O157, have the ability to survive a variety of harsh stress conditions, leading to their entry into the food chain, and subsequent pathogenesis. This research offers insights into the physiological response of this pathogen during the critical period following adaptation to thermal stress and subsequent resumption of growth.     

Early-life maternal separation and social isolation produce an increase in impulsive action but not impulsive choice.

Early life environment, events, and context, such as mother–offspring relationship, can have profound effects on future behavior and physiology. We investigated the effects of long-term maternal and social separation, through artificial rearing, on adult impulsivity. Rats were maternally reared (MR) or artificially reared (AR) and half of the AR rats were provided with replacement somatosensory stimulation intended to simulate maternal licking. There are at least 2 forms of impulsivity and we compared rats on 1 test of impulsive action (differential reinforcement of low rates of responding—DRL-20s) and 2 tests of impulsive choice (delay discounting and fixed consecutive number schedule—FCN). We found that AR rats are more action impulsive; however, this effect can be reduced by maternal licking-like stimulation. In contrast, AR rats did not display an increase in impulsive choice. Overall, these experiments show that early life maternal and social separation have different effects on the 2 forms of impulsivity. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Strengths, strengths overused, and lopsided leadership.

Riding the growth of positive psychology, strengths-based development has become a popular approach to helping managers become better leaders. This school of thought advises managers to maximize their natural talents rather than try to correct weaknesses. This article takes issue with this advice and considers how it can, ironically, lead managers to turn their strengths into weaknesses through overuse as well as cause them to neglect shortcomings that can degrade the performance of employees, teams, and organizations. Hypotheses are developed about the relationship between specific personal strengths and leadership behaviors as well as the joint tendencies to overdo behaviors related to one's strengths while underdoing opposing but complementary behaviors. Strong support was found for the tendency of managers to do too much of the behaviors related to their strengths and more modest support was found for the tendency of managers to do too little of opposing but complementary behaviors. The implications of these findings are discussed in terms of future research needs and how to apply the strengths approach in a way that minimizes downside risk in developmental applications. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Corrosion of high purity Mg, Mg2Zn0.2Mn, ZE41 and AZ91 in Hank’s solution at 37 °C

The CO₂ partial pressure required to maintain a synthetic body fluid (SBF) at a constant pH, based on the initial bicarbonate concentration, was evaluated to be 0.013 atm for Hank’s solution and 0.083 atm for SBF27. Corrosion of high purity Mg and three Mg alloys in Hank’s solution was studied using hydrogen evolution, weight loss and Tafel extrapolation. The solution pH was maintained constant by CO₂. There was initially an incubation period with a low corrosion rate, a period of increasing corrosion rate, and subsequently steady state corrosion. Some hydrogen dissolved in the Mg metal.     

Structure-function studies of an engineered scaffold protein derived from Stefin A. II: Development and applications of the SQT variant

Constrained binding peptides (peptide aptamers) may serve as tools to explore protein conformations and disrupt protein-protein interactions. The quality of the protein scaffold, by which the binding peptide is constrained and presented, is of crucial importance. SQT (Stefin A Quadruple Mutant-Tracy) is our most recent development in the Stefin A-derived scaffold series. Stefin A naturally uses three surfaces to interact with its targets. SQT tolerates peptide insertions at all three positions. Peptide aptamers in the SQT scaffold can be expressed in bacterial, yeast and human cells, and displayed as a fusion to truncated pIII on phage. Peptides that bind to CDK2 can show improved binding in protein microarrays when presented by the SQT scaffold. Yeast two-hybrid libraries have been screened for binders to the POZ domain of BCL-6 and to a peptide derived from PBP2', specific to methicillin-resistant Staphylococcus aureus. Presentation of the Noxa BH3 helix by SQT allows specific interaction with Mcl-1 in human cells. Together, our results show that Stefin A-derived scaffolds, including SQT, can be used for a variety of applications in cellular and molecular biology. We will henceforth refer to Stefin A-derived engineered proteins as Scannins.     

Broadband scattering of the solar spectrum by spherical metal nanoparticles

Metal nanoparticles offer the possibility of improved light trapping in solar cells, but careful design is required to maximise scattering and minimise parasitic absorption across the wavelength range of interest. We present an analysis of the broadband scattering and absorption characteristics of spherical metal nanoparticles, optimized for either crystalline silicon (c‐Si) or amorphous silicon (a‐Si:H) solar cells. A random two‐dimensional array of optimally sized Ag spheres can scatter over 97% of the AM1.5 spectrum from 400 to 1100 nm. Larger particles are required for c‐Si devices than a‐Si:H due to the increased spectral range, with optimum particle sizes ranging from 60 nm for a‐Si:H to 116 nm for c‐Si. Positioning the particles at the rear of the solar cell decreases absorption losses because these principally occur at short wavelengths. Increasing the refractive index of the surrounding medium beyond the optimum value, which is 1.0 for a‐Si:H and 1.6 for c‐Si, shifts absorption to longer wavelengths and decreases scattering at short wavelengths. Ag nanoparticles scatter more of the solar spectrum than Au, Cu or Al nanoparticles. Of these other metals, Al can only be considered for a‐Si:H applications due to high absorption in the near‐infrared, whereas Au and Cu can only be considered for the rear of c‐Si devices due to high absorption in the ultraviolet (UV) and visible. In general, we demonstrate the importance of considering the broadband optical properties of metal nanoparticles for photovoltaic applications. Copyright © 2012 John Wiley & Sons, Ltd.     

FLOCCULATION/COAGULATION OF NATURAL ORGANIC MATTER FOR PRETREATMENT OF WATER AND WASTE WATER

Characterization of water, waste water and natural organic matter are involved in this paper, and as well as the features of flocculation and coagulation for removing natural organic matter from water and waste water Novel flocculant and coagualant is strongly asked for improving removal efficiency and environment friendly. Enhanced coagulation is introduced to meet the experimental and practical requirement.     

Functional Free‐Standing Graphene Honeycomb Films

Fabricating free‐standing, three‐dimensional (3D) ordered porous graphene structure can service a wide range of functional materials such as environmentally friendly materials for antibacterial medical applications and efficient solar harvesting devices. A scalable solution processable strategy is developed to create such free‐standing hierarchical porous structures composed of functionalized graphene sheets via an “on water spreading” method. The free‐standing film shows a large area uniform honeycomb structure and can be transferred onto any substrate of interest. The graphene‐based free‐standing honeycomb films exhibit superior broad spectrum antibacterial activity as confirmed using green fluorescent protein labeled Pseudomonas aeruginosa PAO1 and Escherichia coli as model pathogens. Functional nanoparticles such as titanium dioxide (TiO₂) nanoparticles can be easily introduced into conductive graphene‐based scaffolds by premixing. The formed composite honeycomb film electrode shows a fast, stable, and completely reversible photocurrent response accompanying each switch‐on and switch‐off event. The graphene‐based honeycomb scaffold enhances the light‐harvesting efficiency and improves the photoelectric conversion behavior; the photocurrent of the composite film is about two times as high as that of the pure TiO₂ film electrode. Such composite porous films combining remarkably good electrochemical performance of graphene, a large electrode/electrolyte contact area, and excellent stability during the photo‐conversion process hold promise for further applications in water treatment and solar energy conversion.     

Nonlinear control techniques for an atomic force microscope system

Two nonlinear control techniques are proposed for an atomic force microscope system. Initially, a learning-based control algorithm is developed for the microcantilever-sample system that achieves asymptotic cantilever tip tracking for periodic trajectories. Specifically, the control approach utilizes a learning-based feedforward term to compensate for periodic dynamics and high-gain terms to account for non-periodic dynamics. An adaptive control algorithm is then developed to achieve asymptotic cantilever tip tracking for bounded tip trajectories despite uncertainty throughout the system parameters. Simulation results are provided to illttstrate the efficacy and performance of the control strategies.     

KISTCM: knowledge discovery system for traditional Chinese medicine

Objective: Traditional Chinese Medicine (TCM) provides an alternative method for achieving and maintaining good health. Due to the increasing prevalence of TCM and the large volume of TCM data accumulated though thousands of years, there is an urgent need to efficiently and effectively explore this information and its hidden rules with knowledge discovery in database (KDD) techniques. This paper describes the design and development of a knowledge discovery system for TCM as well as the newly proposed KDD techniques integrated in this system.