Relativistic and Non-Relativistic Quantum Brownian Motion in an Anisotropic Dissipative Medium

Using a minimal-coupling-scheme we investigate the quantum Brownian motion of a particle in an anisotropic-dissipative-medium under the influence of an arbitrary potential in both relativistic and non-relativistic regimes. A general quantum Langevin equation is derived and explicit expressions for quantum-noise and dynamical variables of the system are obtained. The equations of motion for the canonical variables are solved explicitly and an expression for the radiation-reaction of a charged particle in the presence of a dissipative-medium is obtained. Some examples are given to elucidate the applicability of this approach.     

Gaussian-DPSM (G-DPSM) and Element Source Method (ESM) modifications to DPSM for ultrasonic field modeling

In the last few years, Distributed Point Source Method (DPSM) a mesh-free semi-analytical technique has been developed. In spite of its many advantages, one shortcoming of the conventional DPSM method is that the field obtained by conventional DPSM method needs to be scaled to match the theoretical solutions. Two modification techniques called Gaussian-DPSM (G-DPSM) and Element Source Method (ESM) are developed here to avoid the scaling need. G-DPSM technique introduces additional fictitious point sources around every parent point source. Gaussian weight functions determine the strength of these additional fictitious point sources that are denoted as child point sources. ESM replaces discrete point sources used in the conventional DPSM by continuous sources. In the ESM formulation individual point sources are denoted as nodes. Special elements are formed on the boundary by connecting these nodes. The source strength inside the element can vary linearly or non-linearly depending on the order of the interpolation function used inside the element. Results generated by both these methods are compared with the conventional DPSM solution and analytical solution. It is shown that the ultrasonic field in front of the transducer computed by G-DPSM and ESM matches very well with the theory without using any scaling factor.     

The influence of NH3 -attaching on the NMR parameters in the zigzag BN nanotube

Two models of (10, 0) boron nitride nanotubes (BNNTs), perfect and Ammonia-attached, were studied in order to evaluate the influence of NH₃-attaching on the B-11 and N-15 nuclear magnetic resonance in the (10, 0) boron-nitride nanotube (BNNT) for the first time. At first, based on density functional theory (DFT) each of the structures was optimized using B3LYP/6-31G (d) model chemistry. At the next step, the chemical-shielding (CS) tensors were calculated using the B3LYP/6-31G (d, p) level of theory in both of the relaxed forms and were converted to experimentally measurable nuclear magnetic resonance (NMR) parameters, i.e. chemical-shielding isotropic (CSI) and chemical-shielding anisotropic (CSA). Our calculation revealed that in the NH₃-attached BNNT (the most stable model) the B atom chemically bonded to the NH₃ molecule has the largest chemical-shielding isotropic (CSI) and the smallest chemical-shielding anisotropic (CSA) values among the other boron nuclei. Additionally, the NMR parameters of those nuclei directly bonded to the boron dramatically change while those of the other B nuclei remain almost unchanged.     

Novel halogen-free chelated orthoborate-phosphonium ionic liquids: synthesis and tribophysical properties

We report on the synthesis, characterisation, and physical and tribological properties of halogen-free ionic liquids based on various chelated orthoborate anions with different phosphonium cations, both without halogen atoms in their structure. Important physical properties of the ILs including glass transition temperatures, density, viscosity and ionic conductivity were measured and are reported here. All of these new halogen-free orthoborate ionic liquids (hf-BILs) are hydrophobic and hydrolytically stable liquids at room temperature. As lubricants, these hf-BILs exhibit considerably better antiwear and friction reducing properties under boundary lubrication conditions for steel-aluminium contacts as compared with fully formulated (15W-50 grade) engine oil. Being halogen free these hf-BILs offer a more environmentally benign alternative to ILs being currently developed for lubricant applications.     

ITO‐free top emitting organic light emitting diodes with enhanced light out‐coupling

Bottom emitting organic light emitting diodes (OLEDs) can suffer from lower external quantum efficiencies (EQE) due to inefficient out‐coupling of the generated light. Herein, it is demonstrated that the current efficiency and EQE of red, yellow, and blue fluorescent single layer polymer OLEDs is significantly enhanced when a MoO_x(5 nm)/Ag(10 nm)/MoO_x(40 nm) stack is used as the transparent anode in a top emitting OLED structure. A maximum current efficiency and EQE of 21.2 cd/A and 6.7%, respectively, was achieved for a yellow OLED, while a blue OLED achieved a maximum of 16.5 cd/A and 10.1%, respectively. The increase in light out‐coupling from the top‐emitting OLEDs led to increase in efficiency by a factor of up to 2.2 relative to the optimised bottom emitting devices, which is the best out‐coupling reported using solution processed polymers in a simple architecture and a significant step forward for their use in large area lighting and displays.     

Classic Kriging <Emphasis Type="Italic">versus</Emphasis> Kriging with bootstrapping or conditional simulation: classic Kriging’s robust confidence intervals and optimization

Kriging is a popular method for estimating the global optimum of a simulated system. Kriging approximates the input/output function of the simulation model. Kriging also estimates the variances of the predictions of outputs for input combinations not yet simulated. These predictions and their variances are used by ‘efficient global optimization’ (EGO), to balance local and global search. This article focuses on two related questions: (1) How to select the next combination to be simulated when searching for the global optimum? (2) How to derive confidence intervals for outputs of input combinations not yet simulated? Classic Kriging simply plugs the estimated Kriging parameters into the formula for the predictor variance, so theoretically this variance is biased. This article concludes that practitioners may ignore this bias, because classic Kriging gives acceptable confidence intervals and estimates of the optimal input combination. This conclusion is based on bootstrapping and conditional simulation.     

Effect of Hydrophilic/Hydrophobic Block Ratio and Temperature on the Surface and Associative Properties of Oxyethylene and Oxybutylene Diblock Copolymers in Aqueous Media

Recent development in dispersion science and technology demands block copolymers with a variable block length and composition. To highlight that purpose, the surface active, associative, colloidal, and thermodynamic behavior of three diblock copolymers having different hydrophilic to hydrophobic ratio is reported here. Using surface tension and light scattering measurements, the micellization and adsorption behavior of polyoxyethylene and polyoxybutylene diblock copolymers of the type E_mB_n have been analyzed. Critical micelle concentration (CMC) and related thermodynamic parameters like free energy (ΔG_mic), enthalpy (ΔH_mic), and entropy (ΔS_mic) of micellization were calculated from CMC value using the closed association model. Likewise, the surface active parameters, like surface excess concentration (Γ₂), area per molecule (A₂), and thermodynamic parameters such as free energy (ΔG_ads), enthalpy (ΔH_ads), and entropy (ΔS_ads) of adsorption of polymer at the air/water interface, were also calculated at various temperatures. Static and dynamic light scattering techniques were employed for the determination of the weight-average molar (M_w), association number (N_w), polymer–water interaction (A₂), and micellar size in terms of hydrodynamic radii (R_h) of copolymer micelles. The effect of block length and solution temperature on the surface and micellar properties of these copolymers was also investigated.     

Ag2S-石墨烯/TiO2的声化学法合成及可见光催化活性（英文）

Ag2S‐graphene/TiO2 composites were synthesized by a facile sonochemical method.The products were characterized by X‐ray diffraction,scanning electron microscopy,energy dispersive X‐ray spectroscopy,transmission electron microscopy,and UV‐Vis diffuse reflectance spectrophotometry.During the synthesis reaction,the reduction of graphene oxide and loading of Ag2S and TiO2 particles were achieved.The Ag2S‐graphene/TiO2 composites possessed a large adsorption capacity for dyes,an extended light absorption range,and efficient charge separation properties.Hence,in the photodegradation of rhodamine B,a significant enhancement in the reaction rate was observed with the Ag2S‐graphene/TiO2 composites as compared to pure TiO2.The generation of reactive oxygen species was detected by the oxidation of 1,5‐diphenyl carbazide to 1,5‐diphenyl carbazone.The high activity was attributed to the synergetic effects of high charge mobility and the red shift in the absorption edge of the Ag2S‐graphene/TiO2 composites.     

Simulation of Viscoelastic Fluid Flows in Expansion Geometry Using Finite Volume Approach简

The simulation results on viscoelastic fluid flows in sudden expansion geometry with different expansion ratios are presented. Oldroyd-B, linear Phan-Thien-Tanner （L-PTT） and Finitely Extensible Nonlinear Elastic （FENE-P） based constitutive equations were applied in two-dimensional Cartesian coordinates. The governing equations in transient and fully developed regions were solved using open source software called OpenFOAM. The flow patterns, including velocity profiles, shear stresses and first normal stress differences in some horizontal and vertical sections are illustrated. In addition, effects of the fluid type, flow dynamics and expansion ratio on the flow and vortex patterns in transient and fully developed regions are presented and discussed. The presented results show that existences of vortices cause the inverse velocity and negative stresses in expansion regions of the channel which increase with increment of expansion ratio and Weissenberg number （We）. Furthermore, some dead spaces can be observed at channel expansion regions close to the wall which are also increased. The results also show that at low We numbers all fluids show close behavior while at high We numbers the FENE-P fluid behavior shows high divergence from that of the two other fluids.     

Carbon nanotube composite PVC coated stainless steel disc electrode for detection of Ga(III)

This study demonstrates the application of the composite of multi-walled carbon nanotube polyvinylchloride (MWCNT-PVC) based on Bismarck Brown R for gallium sensor. MWCNT has a role to enhance the hydrophobicity of the membrane, which leads to a more stable potential signal. In addition by applying polypyrrol on the surface of this sensor a reduction in the drift of potential occurred and equilibrium potential was achieved faster. Compared to previous studies, using a stainless steel disc instead of a wire electrode causes to obtain an easily and more homogeneous coated electrode. The sensor shows a good Nernstian slope of 19.70?±?0.37?mV?decade^?1 in a wide linear range concentration of 1.0?×?10^?7 to 1.0?×?10^?2?M of Ga(NO₃)₃. The detection limit of this electrode was 7.7?×?10^?8?M of Ga(NO₃)₃. This proposed sensor is applicable in a wide pH range of 2 to 8. It has a short response time of about 8?s and has a good selectivity over twenty four various metal ions. The practical analytical utility of this electrode is demonstrated by measurement of Ga(III) in rock and different water samples.