A facile synthesis of silver nanoparticle with SERS and antimicrobial activity using Bacillus subtilis exopolysaccharides

In this study, we report a facile synthesis of silver nanoparticle having SERS and antimicrobial activity using bacterial exopolysaccharide (EPS). Bacillus subtilis (MTCC 2422) was grown in nutrient broth and the extracellular EPS secreted by the organism was extracted and purified. The purified EPS was used for the synthesis of silver nanoparticles. The kinetics of silver nanoparticle synthesis was deduced by varying the exposure time and the concentration of EPS. The rate constant (k) for the synthesis of silver nanoparticle was calculated from the slope of ln(A^∞ ? A^t) versus time plot. The k value was found to be 3.49 × 10^?3, 5.81 × 10^?3 and 5.03 × 10^?3 per min for particle synthesis using 2, 5 and 10 mg/mL EPS, respectively. The nanoparticles synthesised had an average particle size of 5.18 ± 1.49 nm, 1.96 ± 0.77 nm and 2.08 ± 0.88 nm for 2, 5 and 10 mg/mL EPS, respectively. The synthesised particles were characterised using UV-Vis absorbance spectroscopy, high-resolution transmission electron microscopy (HRTEM) attached to EDS (energy dispersive spectroscopy), Fourier transform infrared spectroscopy (FTIR), surface enhanced Raman spectroscopy (SERS) and zeta potential analyser. To our knowledge, this is the first study to report SERS activity of microbial Bacillus subtilis EPS-based synthesis of silver nanoparticle. HRTEM images showed silver nanoparticle entrapped in polysaccharide nanocages. Silver nanoparticle showed higher adherence towards the bacterial surface, with good bactericidal activity against Pseudomonas aeroginosa and Staphylococcus aureus.     

There is more to anger coping than "in" or "out".

There is growing dissatisfaction with a dichotomized "anger-in" versus "anger-out" view of anger coping. Three studies using student and community adult samples revealed a broader understanding of the nature of anger coping styles and led to the development of the new Behavioral Anger Response Questionnaire (BARQ). The BARQ is empirically derived and factorially validated and has good psychometrics. Results suggest that dichotomizing anger responses as "in" versus "out" is too coarse and that a 6-factor model may be more appropriate. The 6 factors identified here are Direct Anger-Out, Assertion, Support-Seeking, Diffusion, Avoidance, and Rumination. Women reported use of a wider range of anger coping styles, especially more social support-seeking and more use of anger diffusion strategies than men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrooxidation of biologically important hypoxanthine nucleosides and nucleotides at solid electrodes

The oxidation chemistry of hypoxanthine nucleosides and nucleotides viz., inosine, 2′-deoxyinosine, inosine-5′-monophosphate and inosine-5′-triphosphate has been studied in the pH range 2.1-11.1 at pyrolytic graphite electrode. In all the four compounds oxidation occurs in 6H⁺, 6e process at physiological pH (7.2) leading to the formation of allantoin as a major product. The products dimers and tetramers formed in the secondary electrode reactions depend on the nature of sugar molecule (ribose or deoxyribose) present and number of phosphate moieties attached to the sugar moiety. A comparison of redox chemistry and formation of electrooxidised products of inosine and its derivatives has been presented in this paper.     

Effect of Cavities on Creep

The formation of cavities during creep increases the creep rate as a result of the combined effects of the decrease in elastic modulus, which results in elastic creep, and the enhanced rate of the basic creep process caused by stress transfer. Analyses of these effects are presented for the special case of cavities in the form of cracks. The net rate of creep can be described by a total of four terms. Permanent crack-opening displacement resulting from creep deformation of material adjacent to the cracks results in a permanent pore phase following unloading.     

Voltammetric determination of bisoprolol fumarate in pharmaceutical formulations and urine using single-wall carbon nanotubes modified glassy carbon electrode

The electrochemistry of bisoprolol fumarate (BF) has been investigated by differential pulse voltammetry at a single-wall carbon nanotubes (SWNTs) modified glassy carbon electrode (GCE). The prepared electrode showed an excellent electrocatalytic activity towards the oxidation of BF leading to a marked improvement in sensitivity as compared to bare glassy carbon electrode where electrochemical activity for the analyte cannot be observed. The SWNTs-modified GCE exhibited a sharp anodic peak at a potential of ∼950 mV for the oxidation of BF. Under optimum conditions linear calibration curve was obtained over the BF concentration range 0.01-0.1 mM in 0.5 M phosphate buffer solution (pH 7.2) with a correlation coefficient of 0.9789 and detection limit of 8.27 × 10⁻⁷ M. The modified electrode has been applied for the drug determination in human urine with no prior extraction and in commercial tablets. The proposed method has also been validated.     

Experimental study and analysis of air heating system using a parabolic trough solar collector

An experimental study of air heating system was carried out using a parabolic trough collector with a U-tube aluminium heat exchanger. An evacuated tube placed at the focal length of the parabolic trough collected the solar radiations reflected from the surface of parabolic trough. The air was used as a working fluid, which was heated by passing it through a U-shaped aluminium heat exchanger placed inside the evacuated tube. It was found that efficiency of the parabolic trough collector depends on the mass flow rate, solar intensity and use of fins. It was observed that by using fins at a high mass flow rate of 4.557?kg/h, the maximum temperature of 126°C was achieved which is 13.27% more than the maximum temperature obtained without fins. Furthermore, for a low-mass-flow rate of 1.69?kg/h, the maximum temperature obtained was 149°C.     

Artificial neural network model for the estimation of direct solar radiation in the Indian zone

This paper presents a self-consistent model for the estimation of direct solar radiation in the Indian zone. It takes into account the atmospheric transmittance modified in accordance with the climate zone and calculates solar radiation at normal incidence using Hottel's clear day model. The regional weather phenomena are taken into account with the help of variables such as relative humidity, mean duration of sunshine per hour and the rainfall, and a composite parameter referred to as sky clearness index (CI) is determined using artificial neural network analysis. The CI is finally applied to the modified Hottel's clear day model to predict the grey day solar irradiance. The model predictions for the Indian region are found to be in good agreement with the measurements. The variability of sky CI is represented by the contours of constant value in Indian region, which in turn would enable the present model to be used in a self-consistent manner.     

Antioxidant-Rich Extract from Dehydrated Seabuckthorn Berries by Supercritical Carbon Dioxide Extraction

Seabuckthorn (Hippophae rhamnoides L.) berry oil having high nutraceutical, cosmeceutical, and therapeutic activity has been extracted from dried seabuckthorn (SBT) whole berry powder using supercritical carbon dioxide (SC-CO₂), a green process for extraction of bioactives. The SC-CO₂ process was optimized using Box?CBehnken design. Three SC-CO₂ parameters namely extracting pressure, extracting temperature, and time of extraction were examined. The optimal SC-CO₂ conditions were determined, and the quadratic response surfaces were drawn from the mathematical models. A maximum recovery of 85.12% tocopherol, 71.73% carotene, and an EC₅₀ of 29.02?mg/ml (from DPPH assay) was obtained after SC-CO₂ extraction at 44?°C, 345?bar, and run time of 80?min. Use of methanol as an entrainer at 30% v/w of SBT berry at optimized conditions further increased the extraction efficiency and the potency. This extract can be used for varied nutraceutical, cosmeceutical, and pharmaceutical applications.     

Impact of G-Quadruplex Structures on Methylation of Model Substrates by DNA Methyltransferase Dnmt3a

In mammals, de novo methylation of cytosines in DNA CpG sites is performed by DNA methyltransferase Dnmt3a. Changes in the methylation status of CpG islands are critical for gene regulation and for the progression of some cancers. Recently, the potential involvement of DNA G-quadruplexes (G4s) in methylation control has been found. Here, we provide evidence for a link between G4 formation and the function of murine DNA methyltransferase Dnmt3a and its individual domains. As DNA models, we used (i) an isolated G4 formed by oligonucleotide capable of folding into parallel quadruplex and (ii) the same G4 inserted into a double-stranded DNA bearing several CpG sites. Using electrophoretic mobility shift and fluorescence polarization assays, we showed that the Dnmt3a catalytic domain (Dnmt3a-CD), in contrast to regulatory PWWP domain, effectively binds the G4 structure formed in both DNA models. The G4-forming oligonucleotide displaced the DNA substrate from its complex with Dnmt3a-CD, resulting in a dramatic suppression of the enzyme activity. In addition, a direct impact of G4 inserted into the DNA duplex on the methylation of a specific CpG site was revealed. Possible mechanisms of G4-mediated epigenetic regulation may include Dnmt3a sequestration at G4 and/or disruption of Dnmt3a oligomerization on the DNA surface.     

Energy conscious deterministic self-healing new generation wireless sensor network: smart WSN using the <Emphasis Type="Italic">Aatral</Emphasis> framework

It is expected that in the next year, over a billion wireless sensor network (WSN) nodes will be deployed throughout the world, constituting a wide variety of sensor applications. In such a domain, management of the randomly distributed sensor networks is complicated by issues such as knowledge of energy consumption and coverage, extended lifetimes and demands for improved quality of service parameters. Several researchers have addressed these issues through their own innovations and discoveries of different schemes, methods, techniques or mathematical models and architectures or applications, using a variety of node designs. This in turn, has lead to multiple different choices of hardware and software options. However, this has not simplified the process of setting up application testbeds considering energy consumption. There is no readily available solution for setting up a WSN with user selected profiles and parameters. Multiple communication protocols, routing protocols, signal calibration and propagation methods, data aggregation schemes, clustering formations with multiple variations have been proposed for different research objectives. This paper proposes a method for consolidating all the initiatives and integrating these in a service panel framework that helps manage the desired WSN with options to set up an individual WSN profile and supporting the energy engineering processes involved in the WSN.