Thermodynamic and Spectroscopic Studies of Pentoxifylline in Aqueous Glucose/Lactose Solutions

Journal of Solution Chemistry - The density, speed of sound and viscosity data of drug pentoxifylline in aqueous solutions of glucose (monosaccharide) and lactose (disaccharide) were determined....     

Identification of a Potential Inhibitor (MCULE-8777613195-0-12) of New Delhi Metallo-β-Lactamase-1 (NDM-1) Using In Silico and In Vitro Approaches

New Delhi metallo-β-lactamase-1 (NDM-1), expressed in different Gram-negative bacteria, is a versatile enzyme capable of hydrolyzing β-lactam rings containing antibiotics such as penicillins, cephalosporins, and even carbapenems. Multidrug resistance in bacteria mediated by NDM-1 is an emerging threat to the public health, with an enormous economic burden. There is a scarcity in the availability of specific NDM-1 inhibitors, and also a lag in the development of new inhibitors in pharmaceutical industries. In order to identify novel inhibitors of NDM-1, we screened a library of more than 20 million compounds, available at the MCULE purchasable database. Virtual screening led to the identification of six potential inhibitors, namely, MCULE-1996250788-0-2, MCULE-8777613195-0-12, MCULE-2896881895-0-14, MCULE-5843881524-0-3, MCULE-4937132985-0-1, and MCULE-7157846117-0-1. Furthermore, analyses by molecular docking and ADME properties showed that MCULE-8777613195-0-12 was the most suitable inhibitor against NDM-1. An analysis of the binding pose revealed that MCULE-8777613195-0-12 formed four hydrogen bonds with the catalytic residues of NDM-1 (His120, His122, His189, and Cys208) and interacted with other key residues. Molecular dynamics simulation and principal component analysis confirmed the stability of the NDM-1 and MCULE-8777613195-0-12 complex. The in vitro enzyme kinetics showed that the catalytic efficiency (i.e., k_cat/K_m) of NDM-1 on various antibiotics decreased significantly in the presence of MCULE-8777613195-0-12, due to poor catalytic proficiency (k_cat) and affinity (K_m). The IC₅₀ value of MCULE-8777613195-0-12 (54.2 µM) was comparable to that of a known inhibitor, i.e., D-captopril (10.3 µM). In sum, MCULE-8777613195-0-12 may serve as a scaffold to further design/develop more potent inhibitors of NDM-1 and other β-lactamases.     

High-Performance Thin-Layer Chromatographic Determination of Aceclofenac in the Bulk Drug and in Pharmaceutical Preparations

JPC – Journal of Planar Chromatography – Modern TLC -     

Influence of P<Superscript>+</Superscript>-ZnTe back surface contact on photovoltaic performance of ZnTe based solar cells

In order to improve photovoltaic performance of solar cells based on ZnTe thin films two device structures have been proposed and its photovoltaic parameters have been numerically simulated using Solar Cell Capacitance Simulator software. The first one is the ZnO/CdS/ZnTe conventional structure and the second one is the ZnO/CdS/ZnTe/P⁺-ZnTe structure with a P⁺-ZnTe layer inserted at the back surface of ZnTe active layer to produce a back surface field effect which could reduce back carrier recombination and thus increase the photovoltaic conversion efficiency of cells. The effect of ZnO, CdS and ZnTe layer thicknesses and the P⁺-ZnTe added layer and its thickness have been optimized for producing maximum working parameters such as: open-circuit voltage V_oc, short-circuit current density J_sc, fill factor FF, photovoltaic conversion efficiency η. The solar cell with ZnTe/P⁺-ZnTe junction showed remarkably higher conversion efficiency over the conventional solar cell based on ZnTe layer and the conversion efficiency of the ZnO/CdS/ZnTe/P⁺-ZnTe solar cell was found to be dependent on ZnTe and P⁺-ZnTe layer thicknesses. The optimization of ZnTe, CdS and ZnTe layers and the inserting of P⁺-ZnTe back surface layer results in an enhancement of the energy conversion efficiency since its maximum has increased from 10% for ZnO, CdS and ZnTe layer thicknesses of 0.05, 0.08 and 2 µm, respectively to 13.37% when ZnO, CdS, ZnTe and P⁺-ZnTe layer thicknesses are closed to 0.03, 0.03, 0.5 and 0.1 µm, respectively. Furthermore, the highest calculated output parameters have been J_sc?=?9.35 mA/cm², V_oc?=?1.81 V, η?=?13.37% and FF?=?79.05% achieved with ZnO, CdS, ZnTe, and P⁺-ZnTe layer thicknesses about 0.03, 0.03, 0.5 and 0.1 µm, respectively. Finally, the spectral response in the long-wavelength region for ZnO/CdS/ZnTe solar cells has decreased at the increase of back surface recombination velocity. However, it has exhibited a red shift and showed no dependence of back surface recombination velocity for ZnO/CdS/ZnTe/P?+?-ZnTe solar cells.     

Formation of polyampholyte brushes via controlled radical polymerization and their assembly in solution

We describe the formation of polyampholytic block copolymer brushes and their assembly in solution. Specifically, we employ "surface-initiated" activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP) sequentially to form diblock copolymer grafts comprising blocks of poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) and poly(sodium methacrylate) (PNaMA) on flat impenetrable silica surfaces, i.e., SiO(x)/PNaMA-b-PDMAEMA and SiO(x)/PDMAEMA-b-PNaMA. Protonation of the PNaMA block results in formation of poly(methacrylic acid) (PMAA). We demonstrate that ARGET-ATRP of NaMA provides a convenient route to preparation of PMAA, which is an alternative method to the more traditional approach based on preparing PMAA by polymerizing tert-butyl methacrylate (tBMA) followed by cleavage of the tert-butyl group. We also discuss conformational changes of the individual polyelectrolyte blocks in solution as a function of solution pH by monitoring adsorption behavior of functionalized polystyrene spheres.     

125 GeV Higgs,type III seesaw and gauge–Higgs unification

Recently, both the ATLAS and CMS experiments have observed an excess of events that could be the first evidence for a 125 GeV Higgs boson. This is a few GeV below the (absolute) vacuum stability bound on the Higgs mass in the Standard Model (SM), assuming a Planck mass ultraviolet (UV) cutoff. In this Letter, we study some implications of a 125 GeV Higgs boson for new physics in terms of the vacuum stability bound. We first consider the seesaw extension of the SM and find that in type III seesaw, the vacuum stability bound on the Higgs mass can be as low as 125 GeV for the seesaw scale around a TeV. Next we discuss some alternative new physics models which provide an effective ultraviolet cutoff lower than the Planck mass. An effective cutoff Λ?10¹¹ GeV$\Lambda ?{10}^{11}\text{GeV}$ leads to a vacuum stability bound on the Higgs mass of 125 GeV. In a gauge–Higgs unification scenario with five-dimensional flat spacetime, the so-called gauge–Higgs condition can yield a Higgs mass of 125 GeV, with the compactification scale of the extra-dimension being identified as the cutoff scale Λ?10¹¹ GeV$\Lambda ?{10}^{11}\text{GeV}$. Identifying the compactification scale with the unification scale of the SM SU(2) gauge coupling and the top quark Yukawa coupling yields a Higgs mass of 121±2 GeV$121\pm 2\text{GeV}$.     

Superconducting strings in axion models

An SU(5) axion model is discussed in detail to show that axionic strings are superconducting.     

Chaotic inflation,radiative corrections and precision cosmology

We employ chaotic (?²${?}^2$ and ?⁴${?}^4$) inflation to illustrate the important role radiative corrections can play during the inflationary phase. Yukawa interactions of ?  , in particular, lead to corrections of the form −κ?⁴ln(?/μ)$-\kappa {?}^4\ln (?/\mu )$, where κ>0$\kappa >0$ and μ   is a renormalization scale. For instance, ?⁴${?}^4$ chaotic inflation with radiative corrections looks compatible with the most recent WMAP (5 year) analysis, in sharp contrast to the tree level case. We obtain the 95% confidence limits 2.4×¹⁰⁻¹⁴?κ?5.7×¹⁰⁻¹⁴$2.4\times {10}^{\mathrm{-14}}?\kappa ?5.7\times {10}^{\mathrm{-14}}$, 0.931?ns?0.958$0.931?n_s?0.958$ and 0.038?r?0.205$0.038?r?0.205$, where ns$n_s$ and r   respectively denote the scalar spectral index and scalar to tensor ratio. The limits for ?²${?}^2$ inflation are κ?7.7×¹⁰⁻¹⁵$\kappa ?7.7\times {10}^{\mathrm{-15}}$, 0.929?ns?0.966$0.929?n_s?0.966$ and 0.023?r?0.135$0.023?r?0.135$. The next round of precision experiments should provide a more stringent test of realistic chaotic ?²${?}^2$ and ?⁴${?}^4$ inflation.     

Structure determination of 3β-acetoxy-cholest-5-ene-7-one—A steroid

The crystal structure of 3β-acetoxy-cholest-5-ene-7-one (C₂₉H₄₆O₃) has been determined by X-ray diffraction methods. The compound crystallizes in the monoclinic crystal system (space group P2₁) with the unit cell parameters a = 9.632(1) Å, b = 12.280(1) Å, c = 23.099(2) Å, β = 99.52(1)°, and Z = 4. The structure has been solved by direct methods and refined to an R-value of 0.065 for 3927 observed reflections [F ₀ > 4σ(F ₀)]. Two crystallographically independent molecules (I and II) in the asymmetric unit have been observed. In both molecules, rings A and C of the steroid nucleus exist in a chair conformation. Ring B of molecule I adopts a 5α,6β half-chair conformation, and ring B of molecule II shows a 6α sofa conformation. Ring D adopts a 13α,14β half-chair conformation in molecule I and a 13α,14β half-chair conformation in molecule II. The crystal structure is stabilized by the intramolecular and intermolecular C-H?O interactions.