New quasi-planar surfaces of bare boron

New very stable quasi-planar clusters of bare boron are found by systematic ab initio density functional and quantum chemical methods. They are composed of dove-tailed hexagonal pyramids different from the classical forms of - or β-rhombohedral boron crystallines. The quasi-planar structures are considered to be fragments of quasi-planar surfaces, which can easily be obtained and constructed from a basic unit of hexagonal pyramids. A new investigation on double layers of boron quasi-planar surfaces shows an increase in the stability of the system which can be related to the overlap of π-orbitals between the layers. Therefore, we predict the existence of a series of parallel boron layers, as in graphite. These proposed surfaces can serve as lightweight protective armor, as a neutron-absorber material in fission reactions, or as very high temperature semiconductors.     

Some Electromagnetic Transition Properties of Odd-A Europium Isotopes

In this work, we analyze the positive parity of states of odd-A Eu isotopes within the framework of interacting boson fermion model （IBFM-1）. The result of an IBFM-1 multilevel calculation with the 3s1/2, 2d3/2, 2d5/2, and 1g7/2 single panicle orbits is reported for the positive parity states of the odd-A Eu isotopes. A/so, an IBM-1 calculation is presented for the low-lying states in the even-even 152-154Sm core nucleus. The energy levels and B（E2） transition probabilities are calculated and compared with the experimental data. It is found that the calculated positive parity low spin state energy spectra of the odd-A Eu isotopes agree quite well with the experimental data.     

Creeping flow analysis of slightly non-Newtonian fluid in a uniformly porous slit

This paper provides the analysis of the steady, creeping flow of a special class of slightly viscoelastic, incompressible fluid through a slit having porous walls with uniform porosity. The governing two dimensional flow equations along with non-homogeneous boundary conditions are non-dimensionalized. Recursive approach is used to solve the resulting equations. Expressions for stream function, velocity components, volumetric flow rate, pressure distribution, shear and normal stresses in general and on the walls of the slit, fractional absorption and leakage flux are derived. Points of maximum velocity components are also identified. A graphical study is carried out to show the effect of porosity and non-Newtonian parameter on above mentioned resulting expressions. It is observed that axial velocity of the fluid decreases with the increase in porosity and non-Newtonian parameter. The outcome of this theoretical study has significant importance both in industry and biosciences.     

A Simplified Novel Technique for Solving Fully Fuzzy Linear Programming Problems

This study proposes a novel technique for solving Linear Programming Problems in a fully fuzzy environment. A modified version of the well-known simplex method is used for solving fuzzy linear programming problems. The use of a ranking function together with the Gaussian elimination process helps in solving linear programming problems in a fully uncertain environment. The proposed algorithm is flexible, easy and reasonable.     

Preparation of highly efficient Al-doped ZnO photocatalyst by combustion synthesis

Novel Al-doped ZnO (AZO) photocatalysts with different Al concentrations (0.5–6.0 mol%) were prepared through a facile combustion method and followed by calcination at 500 °C for 3 h. The obtained nanopowders were characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) combined with EDX, transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy and photoluminescence spectroscopy. The XRD patterns of AZO nanopowders were assigned to wurtzite structure of ZnO with the smallest crystallite size about 11 nm consistent with the results from TEM. The doping of Al in ZnO crystal structure successfully suppressed the growth of ZnO nanoparticles confirmed by XRD patterns. The absorption spectra analysis showed that the optical band gap energy (E_g) for the AZO nanopowders were in the range of 3.12–3.21 eV and decreased with increasing of Al dopant. The photocatalytic activities of the samples were evaluated by photocatalytic degradation of methyl orange under visible light (λ ≥ 420 nm) and sunlight irradiation. The results showed that the AZO photocatalyst doped with 4.0 mol% Al exhibited five times enhanced photocatalytic activity compared to pure ZnO. The enhanced photocatalytic activity could be attributed to extended visible light absorption, inhibition of the electron–hole pair's recombination and enhanced adsorptivity of MO dye molecule on the surface of AZO nanopowders.     

A new proposed model of restricted data envelopment analysis by correlation coefficients

The concept of efficiency in data envelopment analysis (DEA) is defined as weighted sum of outputs/weighted sum of inputs. In order to calculate the maximum efficiency score, each decision making unit (DMU)’s inputs and outputs are assigned to different weights. Hence, the classical DEA allows the weight flexibility. Therefore, even if they are important, the inputs or outputs of some DMUs can be assigned zero (0) weights. Thus, these inputs or outputs are neglected in the evaluation. Also, some DMUs may be defined as efficient even if they are inefficient. This situation leads to unrealistic results. Also to eliminate the problem of weight flexibility, weight restrictions are made in DEA. In our study, we proposed a new model which has not been published in the literature. We describe it as the restricted data envelopment analysis ((ARIII(COR))) model with correlation coefficients. The aim for developing this new model, is to take into account the relations between variables using correlation coefficients. Also, these relations were added as constraints to the CCR and BCC models. For this purpose, the correlation coefficients were used in the restrictions of input–output each one alone and their combination together. Inputs and outputs are related to the degree of correlation between each other in the production. Previous studies did not take into account the relationship between inputs/outputs variables. So, only with expert opinions or an objective method, weight restrictions have been made. In our study, the weights for input and output variables were determined, according to the correlations between input and output variables. The proposed new method is different from other methods in the literature, because the efficiency scores were calculated at the level of correlations between the input and/or output variables.     

Catalytic comparison of various polar Zn(II)-Schiff base complexes and VO(II)-Schiff base complexes in (ep)oxidation processes of 1,2-cyclohexene and cyclohexane

Research on Chemical Intermediates - The reactivity of Zn2+ and VO2+ ions towards pyridinyl Schiff bases, in the absence or presence of a p-sodium sulfonate group (HPSNa and HPS, respectively),...     

Hybrid cross‐linked hydrogels as a technology platform for in vitro release of cephradine

Hydrogel‐based drug delivery systems can leverage therapeutically favorable upshots of drug release and found clinical uses. Hydrogels offer temporal and spatial control over the release of different therapeutic agents. Because of their tailor made controllable degradability, physical properties, and ability to prevent the labile drugs from degradation, hydrogels provide platform on which diverse physicochemical interactions with entrapped drugs cause to control drug release. Herein, we report the fabrication of novel vinyltrimethoxy silane (VTMS) cross‐linked chitosan/polyvinyl pyrrolidone hydrogels. Swelling in distilled water in conjunction with different buffer and electrolyte solutions was performed to assess the swellability of hydrogels. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X‐ray diffraction (XRD) analysis were further conducted to investigate the possible interactions between components, thermal stability, and crystallinity of as‐prepared hybrid hydrogels, respectively. In vitro time‐dependent biodegradability, antimicrobial study, and cytotoxicity were also carried out to evaluate their extensive biocompatibility and cytotoxic behavior. More interestingly, in vitro drug release study allowed for the controlled release of cephradine. Therefore, this facile strategy developed the novel biocompatible and biodegradable hybrid hydrogels, which could significantly expand the scope of these hydrogels in other biomedical applications like scaffolds, skin regeneration, tissue engineering, etc.     

Nonradiative Excited-State Decay via Conical Intersection in Graphene Nanostructures

Chemical groups are known to tune the luminescent efficiencies of graphene-related nanomaterials, but some species, including the epoxide group (−COC−), are suspected to act as emission-quenching sites. Herein, by performing nonadiabatic excited-state dynamics simulations, we reveal a fast (within 300 fs) nonradiative excited-state decay of a graphene epoxide nanostructure from the lowest excited singlet (S₁) state to the ground (S₀) state via a conical intersection (CI), at which the energy difference between the S₁ and S₀ states is approximately zero. This CI is induced after breaking one C−O bond at the −COC− moiety during excited-state structural relaxation. This study ascertains the role of epoxide groups in inducing the nonradiative recombination of the excited electron-hole, providing important insights into the CI-promoted nonradiative de-excitations and the luminescence tuning of relevant materials. In addition, it shows the feasibility of utilizing nonadiabatic excited-state dynamics simulations to investigate the photophysical processes of the excited states of graphene nanomaterials.