Applied Science Private University

About: Applied Science Private University is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Catalysis & Population. The organization has 4124 authors who have published 5299 publications receiving 116167 citations.

An optical sensor for nitrogen dioxide based on a copper phthalocyanine Langmuir—Blodgett film

Abstract: A copper phthalocyanine Langmuir—Blodgett film has been incorporated in an optical gas sensor which exploits the phenomenon of surface plasmon resonance. For the detection of nitrogen dioxide, a significant improvement over previous work is demonstrated. The use of an ultra-thin layer of nickel to protect the underlying silver layer is also reported.

Dynamics of dissociative attachment of electrons to water through the {sup 2}B{sub 1} metastable state of the anion

Abstract: Calculations of cross sections for dissociative attachment to water through the $^{2}B_{1}$ resonance state are presented using the ab initio surfaces calculated previously for the energy ${E}_{R}$ and width $\ensuremath{\Gamma}$ of this resonance state as a function of nuclear geometry. The dynamics of the dissociative attachment process are treated in full dimensionality using the local complex potential model. For the ${\mathrm{H}}^{\ensuremath{-}}+\mathrm{OH}$ channel, the calculations presented here are in substantial agreement with experiment with regard to total cross section and vibrational excitation of the $\mathrm{OH}$ fragment. Cross sections for dissociative attachment to excited initial ro-vibrational states are presented and isotope effects are also examined.

Filter-and-Forward Distributed Beamforming for Two-Way Relay Networks With Frequency Selective Channels

Abstract: In filter-and-forward (FF) based two-way relay networks, each transmission for data exchange between two transceivers consists of only two time slots (or phases). In the first time slot, both transceivers transmit their data simultaneously to the relays. The received signal of each relay is filtered using a finite impulse response (FIR) filter to compensate for the frequency selectivity of the channels, and then, the output of the filter is forwarded to both transceivers in the second time-slot. In this paper, new approaches to distributed cooperative beamforming for such two-way relay networks with frequency selective channels are proposed. The first two distributed beamforming approaches assume that the transmitted powers of the transceivers are given and fixed. The first beamformer is based on minimizing the total transmitted power of the relays subject to two constraints on the signal-to-inter-symbol-interference-plus-noise ratio (SINR) at both transceivers. The second beamformer is designed through maximization of the lowest SINR of the two transceivers while keeping the relay transmitted power under certain levels. We show that these two problems can be cast as second-order convex cone programming problems. The other two distributed beamforming methods aim to calculate the transmitted powers of the transceivers as well as the coefficients of the relay filters using two different beamforming techniques. The first technique is based on the minimization of the total transmitted power of the transceivers and the relays subject to the SINR requirements for both transceivers, and the second method maximizes the lowest SINR of the two transceivers subject to a constraint on the total transmitted power. Simulation results demonstrate that using an FF relaying strategy can significantly improve the underlying performance measure as compared to the traditional amplify-and-forward relaying approach.

The effect of subminimal inhibitory concentrations of antibiotics on virulence factors expressed by Staphylococcus aureus biofilms

Abstract: Aims: The effect of subminimal inhibitory concentrations (sub-MICs) of cefalexin, ciprofloxacin and roxithromycin was investigated on some virulence factors [eg coagulase, Toxic Shock Syndrome Toxin 1 (TSST-1) and biofilm formation] expressed by Staphylococcus aureus biofilms Methods and Results: Biofilms were grown with and without the presence of 1/16 MIC of antibiotics on Sorbarod filters Eluate supernatants were collected, and coagulase and TSST-1 production were evaluated Coagulase production was reduced in eluates exposed to roxithromycin when compared to control, while TSST-1 production was reduced in biofilms exposed to cefalexin and to a lesser extent, ciprofloxacin In addition, the ability of Staph aureus to produce biofilm in microtitre plates in the presence of sub-MIC antibiotics indicated that cefalexin induced biofilm formation at a wide range of sub-MICs TSST-1 produced from the challenged and control biofilms was purified, and its proliferative activity was studied on single cell suspension of mouse splenocytes using MTS/PMS assay No significant difference in the activity between the treated toxin and the control has been observed Conclusions: Antibiotics at sub-MIC levels interfere with bacterial biofilm virulence expression depending on the type and concentration of antibiotic used Significance and Impact of the Study: The establishment of sub-MICs of antibiotics in clinical situations may result in altered virulence states in pathogenic bacteria

How selection affects phenotypic fluctuation.

Abstract: The large degree of phenotypic fluctuation among isogenic cells highlighted by recent studies on stochastic gene expression confers fitness on some individuals through a ‘bet‐hedging’ strategy, when faced with different selective environments. Under a single selective environment, the fluctuation may be suppressed through evolution, as it prevents maintenance of individuals around the fittest state and/or function. However, as fluctuation can increase phenotypic diversity, similar to mutation, it may contribute to the survival of individuals even under a single selective environment. To discuss whether the fluctuation increases over the course of evolution, cycles of mutation and selection for higher GFP fluorescence were carried out in Escherichia coli . Mutant genotypes possessing broad GFP fluorescence distributions with low average values emerged under strong selection pressure. These ‘broad mutants’ appeared independently on the phylogenetic tree and increased fluctuations in GFP fluorescence were attributable to the variance in mRNA abundance. In addition to the average phenotypic change by genetic mutation, the observed increase in phenotypic fluctuation acts as an evolutionary strategy to produce an extreme phenotype under severe selective environments. Mol Syst Biol. 5: 264