Ground state energy of He isoelectronic sequence treated variationally via Hylleraas-like wavefunction

In this study, the energy for the ground state of helium and a few helium-like ions (Z=1-6) is computed variationally by using a Hylleraas-like wavefunction. A four-parameters wavefunction, satisfying boundary conditions for coalescence points, is combined with a Hylleraas-like basis set which explicitly incorporates r12 interelectronic distance. The main contribution of this work is the introduction of modified correlation terms leading to the definition of integral transforms which provide the calculation of expectation value of energy to be done analytically over single-particle coordinates instead of Hylleraas coordinates.     

Characterization and evaluation of the photocatalytic properties of wormhole-like mesoporous silica incorporating TiO2, prepared using different hydrothermal and calcination temperatures

TiO₂?CSiO₂ mesoporous materials were synthesised by deposition of TiO₂ nanoparticles prepared by the sol?Cgel method on to the internal pore surface of wormhole-like mesoporous silica. In this work we synthesised wormhole-like mesoporous silica of different surface area by changing the hydrothermal temperature (70, 100, or 130?°C). Subsequent to this, titania solution was deposited on to the inner surface of the pores and this was followed by calcination at different temperatures (400, 600, or 800?°C). The effect of different hydrothermal and calcination temperature on the photocatalytic properties was evaluated. The samples were characterized by N₂-sorption, X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The effect of different hydrothermal and calcination temperatures on the photocatalytic properties was evaluated by measuring the degradation of methylene blue in aqueous solution under UV light irradiation (mercury lamp, 125?W). The results indicated that appropriate surface area and degree of crystallinity are two important factors for obtaining high photocatalytic efficiency. Samples prepared at a hydrothermal temperature of 100?°C and calcined at 800?°C had the best photocatalytic performance, because of the highest surface area and high crystallinity.     

Electronic states of the benzene dimer: a simple case of complexity

Electronic structure calculations of the excited states of the benzene dimer using equation-of-motion coupled-cluster method are reported. The calculations reveal large density of electronic states, including multiple valence, Rydberg, and mixed Rydberg-valence states. The calculations of the oscillator strengths for the transitions between the excimer state (i.e., the lowest excited state of the dimer, 1(1)B(1g)) and other excited states allowed us to identify the target state responsible for the excimer absorption as the E(1u) state of a mixed Rydberg-valence character at 3.04 eV above the excimer (1(1)B(1g)). Although at D(6h) the 1(1)B(1g) → E(1u) transition is symmetry-forbidden, small geometric displacements (to D(2h)) that have a negligible effect on the excitation energy split this degenerate state into the dark (4B(3u)) and bright (4B(2u)) components (oscillator strength of 0.3 au). The excitation energy for this transition depends strongly on the dimer structure, which explains the broad character of the experimentally observed excimer absorption spectrum.     

Voltammetric and electrochemical impedimetric behavior of silica-based gel electrolyte for valve-regulated lead-acid battery

The gel electrolyte is an important component of the valve-regulated lead-acid (VRLA) batteries. In this study, fumed silica-based gel electrolyte systems were prepared. In this concept, several important parameters controlling the performance of the GEL-VRLA battery, such as the sulfuric acid and fumed silica concentrations, gel formulation, gelling time and rate, and different additives (Na₂SO₄ and MgSO₄), were scientifically investigated. The gel formulations were characterized by cyclic voltammetric and electrochemical impedance spectroscopic methods. The optimum parameters were determined by using the results of anodic peak currents and redox capacities, R _s and R _ct values. Addition of 6 % (w/w) fumed silica to 30 % (w/w) sulfuric acid, for preparation of gelled electrolyte, increased the battery performance significantly. According to the results of the transmission electron and optic microscope images of the gel electrolytes, the three-dimensional gel structure was prepared successfully. The optimization of sulfuric acid concentration and amount of Na₂SO₄ and MgSO₄ additives were examined for the first time in detail by cyclic voltammetry, electrochemical impedimetry, and battery test. Na₂SO₄ and MgSO₄ additives make a good combination with a gelled-electrolyte system and improve the charge/discharge capacity according to sulfuric acid electrolytes. According to the experimental results, the fumed silica-based gel electrolyte system has a great potential for application in gelled electrolyte VRLA batteries.     

Modified gold surfaces by poly(amidoamine) dendrimers and fructose dehydrogenase for mediated fructose sensing

An electrochemical biosensor for detection of fructose in food samples was developed by immobilization of fructose dehydrogenase (FDH) on cysteamine and poly(amidoamine) dendrimers (PAMAM)-modified gold electrode surface. Electrochemical analysis was carried out by using hexacyanoferrate (HCF) as a mediator and the response time was 35 s at +300 mV vs. Ag/AgCl. Moreover, some parameters such as pH, enzyme loading and type of PAMAM (Generations 2, 3 and 4) were investigated. Then, the FDH biosensor was calibrated for fructose in the concentration range of 0.25–5.0 mM. To evaluate its utility, the FDH biosensor was applied for fructose analysis in real samples. Finally, obtained data were compared with those measured with HPLC as a reference method.     

Color image encryption using Choquet fuzzy integral and hyper chaotic system

This paper proposes a color image encryption scheme based on Choquet fuzzy integral (CFI) and hyper chaotic system. The major core of the encryption algorithm is a pseudo-random number generator based on the CFI. Before encrypting the color image, the piecewise linear chaotic map (PWLCM) is used to generate the 128-bit secret keys, and the Lorenz system is iterated for limited times to generate the initial parameters of the CFI. The outputs of the CFI are used to confuse and diffuse the three components of the pixel, respectively. Experiment results and security analysis show that the scheme not only can achieve good encryption result and large key space, but also can resist against common attacks, so the scheme is reliable to be adopted for network security and secure communications.     

ChemInform Abstract: Structural Characterization of Sr4Mg4H4[CoH5]3 Shows the Importance of Support from Polarizing Counter Ions to 3d Transition Metal Hydrido Complexes.

The title compound is prepared by high‐pressure solid state reaction of a 4:1:2 mixture of SrH₂, Co, and Mg₂CoH₅ (autoclave, 60 bar H₂, 873 K, 12 h).     

Microwave-accelerated metal-enhanced fluorescence: application to detection of genomic and exosporium anthrax DNA in <30 seconds

We describe the ultra-fast and sensitive detection of the gene encoding the protective antigen of Bacillus anthracis the causative agent of anthrax. Our approach employs a highly novel platform technology, Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF), which combines the use of Metal-Enhanced Fluorescence to enhance assay sensitivity and focused microwave heating to spatially and kinetically accelerate DNA hybridization. Genomic and exosporium target DNA of Bacillus anthracis spores was detected within a minute in the nanograms per microliter concentration range using low-power focused microwave heating. The MAMEF technology was able to distinguish between B. anthracis and B. cereus, a non-virulent close relative. We believe that this study has set the stage and indeed provides an opportunity for the ultra-fast and specific detection of B. anthracis spores with minimal pre-processing steps using a relatively simple but cost-effective technology that could minimize casualties in the event of another anthrax attack.     

Impact of lepton p_T threshold on charge asymmetry predictions for inclusive W boson production in pp collisions at 13 TeV

This paper presents the impact of the lepton transverse momentum p_T~l threshold on the W boson charge asymmetry predictions in perturbative QCD for the inclusive W~++X→l~±v+X production in proton-proton(pp)collisions.The predictions are obtained at various low-p_T~l thresholds p_T~l 20,25,30,and 40 GeV in a fiducial region encompassing both the central and forward detector acceptances in terms of the lepton pseudorapidity0 ≤η_l≤4.5.The predicted distributions for the lepton charge asymmetry,which is defined by η_l(A_(η_l)),at the nextto-next-to-leading order(NNLO) accuracy are compared with the CMS and LHCb data at 8 TeV center-of-mass collision energy.The 8 TeV predictions reproduce the data fairly well within the quoted uncertainties.The predictions from the CT14 parton distribution function(PDF) model are in a slightly better agreement with the data over the other PDF sets that are tested.The 13 TeV predictions using various p_T~l thresholds are reported for A_(η_l) and the charge asymmetries that are defined in terms of the differential cross sections in bins of the W boson rapidity yw(A_(y_w)) and transverse momentum p_T~W(A_(p_T~W)).The NNLO predictions for the A_(η_l),A_(y_w).and A_(p_T~W) distributions are assessed to be in close correlation with the p_T~l value.The A_(η_l) and A_(y_w) distributions are particularly shown to be more correlated at a higher p_T~l threshold.The A_(p_T~W) distributions are also reported from the merged predictions with improved accuracy by the inclusion of the next-to-next-to-next-to-leading logarithm(N'LL) corrections,i.e.,at NNLO+N~3 LL.The predicted distributions from various p_T~l thresholds represent a finer probe in terms of the capability to provide more constraints on the ratio of u and d quark distribution functions in the parton momentum fraction range 10~(-4) x1.     

A New Method for the Synthesis of Antihypercholesterolemic Agent Simvastatin

A new synthetic method for the preparation of the cholesterol‐lowering drug simvastatin from the naturally occurring lovastatin is reported. The synthesis employs first the protection of the OH group of lovastatin ( 1 ) and then the protection of the lactone C?O group to prevent enolization via conversion to the orthoesters 4a and 4b . Alkylation of the 2‐methylbutyrate side chain is then successfully achieved. Removal of the protecting groups affords antihypercholesterolemic agent simvastatin ( 2 ).