A Comprehensive Computational Investigation into the Conserved Virulent Proteins of Shigella species Unveils Potential Small-Interfering RNA Candidates as a New Therapeutic Strategy against Shigellosis

Shigella species account for the second-leading cause of deaths due to diarrheal diseases among children of less than 5 years of age. The emergence of multi-drug-resistant Shigella isolates and the lack of availability of Shigella vaccines have led to the pertinence in the efforts made for the development of new therapeutic strategies against shigellosis. Consequently, designing small-interfering RNA (siRNA) candidates against such infectious agents represents a novel approach to propose new therapeutic candidates to curb the rampant rise of anti-microbial resistance in such pathogens. In this study, we analyzed 264 conserved sequences from 15 different conserved virulence genes of Shigella sp., through extensive rational validation using a plethora of first-generation and second-generation computational algorithms for siRNA designing. Fifty-eight siRNA candidates were obtained by using the first-generation algorithms, out of which only 38 siRNA candidates complied with the second-generation rules of siRNA designing. Further computational validation showed that 16 siRNA candidates were found to have a substantial functional efficiency, out of which 11 siRNA candidates were found to be non-immunogenic. Finally, three siRNA candidates exhibited a sterically feasible three-dimensional structure as exhibited by parameters of nucleic acid geometry such as: the probability of wrong sugar puckers, bad backbone confirmations, bad bonds, and bad angles being within the accepted threshold for stable tertiary structure. Although the findings of our study require further wet-lab validation and optimization for therapeutic use in the treatment of shigellosis, the computationally validated siRNA candidates are expected to suppress the expression of the virulence genes, namely: IpgD (siRNA 9) and OspB (siRNA 15 and siRNA 17) and thus act as a prospective tool in the RNA interference (RNAi) pathway. However, the findings of our study require further wet-lab validation and optimization for regular therapeutic use for treatment of shigellosis.     

Experimental and kinetic study of shock initiated ignition in homogeneous methane–hydrogen–air mixtures at engine‐relevant conditions

The ignition delay time of two stoichiometric methane/hydrogen/air mixtures has been measured in a shock tube facility at pressures from 16 to 40 atm and temperatures from 1000 to 1300 K. Overall, the observed reduction in ignition delay with some methane replaced by hydrogen is relatively small given the large concentration of hydrogen involved in the current study. With a high hydrogen mole fraction (35% of the total fuel), a reduction of the ignition‐promoting effect was observed with reduced temperature. A detailed chemical kinetic mechanism was used to simulate ignitions of test mixtures behind reflected shocks. An analysis of the mechanism indicates that at higher temperatures, the rapid decomposition of hydrogen molecules leads to a quick formation of H radical pools, which promote the chain branching through H + O₂ ? O + OH. At lower temperatures, the branching efficiency of hydrogen is low; a weak effect of hydrogen on methane ignition could be result from the reaction between H₂ and methylperoxy CH₃O₂, which contributes extra H radicals to the reaction system. The effects of hydrogen also decrease with increasing pressure; this is related to the negative pressure dependence of hydrogen at the second ignition limit. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 221–233, 2006     

Can van Hove singularities be observed in relativistic heavy-ion collisions?

Based on general arguments, the in-medium quark propagator in a quark-gluon plasma leads to a quark dispersion relation consisting of two branches, of which one exhibits a minimum at some finite momentum. This results in a vanishing group velocity for collective quark modes. Important quantities such as the production rate of low mass lepton pairs and mesonic correlators depend inversely on this group velocity. Therefore these quantities, which follow from self energy diagrams containing a quark loop, are strongly affected by van Hove singularities (peaks and gaps). If these sharp structures could be observed in relativistic heavy-ion collisions it would reveal the physical picture of the quark-gluon plasma (QGP) as a gas of quasiparticles.     

Modified <Emphasis Type="Italic">Rhizopus arrhizus</Emphasis> biomass for sorption of <Superscript>241</Superscript>Am and other radionuclides

The improvement and the refinement of non-viable Rhizopus arrhizus biomass were investigated via immobilization. Immobilization was carried out by using sodium alginate/CaCl₂ solution and formaldehyde/HCl cross-linking with dead Rhizopus arrhizus biomass and were used for the sorption of radionuclides from low level effluent wastes. The sodium alginate/CaCl₂ immobilized biomass (ratio 1:2) showed about 86% sorption for ²⁴¹Am activity but due to its soft nature and tendency to undergo distortion in shape, is unsuitable for practical applications. The biomass cross-linked with 15% formaldehyde/0.1 M HCl solution has a relatively high mechanical strength and rigidity. It was showing a sorption of >99% for ²⁴¹Am activity and has the sorption capacity of ~65 mg/g for americium and uranium. Hence, it can be utilized for the removal of radionuclides from radioactive waste effluents.     

One-Pot Dual C−C Coupling Reaction via Site Selective Cascade Formation by PdII-Cryptate of an Amino-Ether Heteroditopic Macrobicycle

Selectivity of aryl iodo over ethynyl iodo toward the Suzuki cross coupling reaction is explored by utilizing a palladium complex of amino-ether heteroditopic macrobicycle. Subsequently, unreacted ethynyl iodide undergoes homocoupling reaction in the same catalytic atmosphere, thereby representing a cascade dual C−C coupling reaction. Furthermore, this approach is extended for novel one-pot synthesis of unsymmetrical 1,3-diynes.     

Interfaces as design tools for short-period InAs/GaSb type-II superlattices for mid-infrared detectors

The effect of interface anisotropy on the electronic structure of InAs/GaSb type-II superlattices is exploited in the design of thin-layer superlattices for mid-IR detection threshold. The design is based on a theoretical envelope function model that incorporates the change of anion and cation species across InAs/GaSb interfaces, in particular, across the preferred InSb interface. The model predicts that a given threshold can be reached for a range of superlattice periods with InAs and GaSb layers as thin as a few monolayers. Although the oscillator strengths are predicted to be larger for thinner period superlattices, the absorption coefficients are comparable because of the compensating effect of larger band widths. However, larger intervalence band separations for thinner-period samples should lead to longer minority electron Auger lifetimes and higher operating temperatures in p-type SLs. In addition, the hole masses for thinner-period samples are on the order the free-electron mass rather than being effectively infinite for the wider period samples. Therefore, holes should also contribute to photoresponse. A number of superlattices with periods ranging from 50.6 to 21.2 Å for the 4 μm detection threshold were grown by molecular beam epitaxy based on the model design. Low temperature photoluminescence and photoresponse spectra confirmed that the superlattice band gaps remained constant at 330 meV although the period changed by the factor of 2.5. Overall, the present study points to the importance of interfaces as a tool in the design and growth of thin superlattices for mid-IR detectors for room temperature operation.     

Quenching of hadron spectra due to the collisional energy loss of partons in the quark-gluon plasma

We estimate the energy loss distribution and investigate the quenching of hadron spectra in ultrarelativistic heavy-ion collisions due to the collisional energy loss of energetic partons from hard parton collisions in the initial stage.     

Color schlieren deflectometry study of jet mixing: effect of buoyancy and perforation

Mixing of jets is crucial for optimal performance of many industrial applications and there is a need to optimize both nozzle geometry and flow conditions. The present study reports the influence of buoyancy and perforation on mixing between a jet and its environment. Optical techniques are ideal for the study of jet mixing due to their non-intrusive and inertia free properties. The present study gives an account of mixing between helium jet and the ambient fluid using a combination of color schlieren deflectometry and radial tomographic mathematics. Four different perforation sizes have been used and the experiments are performed for Reynolds numbers 21–676 and Richardson numbers 3.27–0.0015. Color schlieren images show distinct influence of perforation and flow conditions (Richardson number). Oxygen concentration and jet width quantify effectiveness of jet mixing. Buoyancy plays an important role in mixing at high Richardson number. Perforation improves jet mixing i.e. there is about 120% increase in jet width and the size of perforation plays an important role.     

Comparison of near infrared laser excitation wavelengths and its influence on the interrogation of seized drugs‐of‐abuse by Raman spectroscopy

The laser excitation wavelength is an important parameter in obtaining Raman spectra from drugs‐of‐abuse. This article compares the effect of near infrared wavelengths, 785 nm, using both benchtop and portable instrumentation and benchtop 1064 nm on the Raman spectra of seized drugs‐of‐abuse, including cocaine hydrochloride, cocaine freebase (crack), methylenedioxymethamphetamine (‘ecstasy’), amphetamine, diamorphine (heroin) and cannabis. The significant benefit of using 1064 nm for the interrogation of this type of sample is highlighted. Copyright © 2009 John Wiley & Sons, Ltd.