Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature

This study extends the investigation of quantum dissipative effects of a cosmological scalar field by taking into account cosmic expansion and contraction.Cheung,Drewes,Kang,and Kim calculated the effective action and quantum dissipative effects of a cosmological scalar field in a recent work,where analytical expressions for the effective potential and damping coefficient were presented using a simple scalar model with quartic interactions,and the work was conducted using Minkowski-space propagators in loop diagrams.In this work,we incorporate the Hubble expansion and contraction of the cosmic background and focus on the thermal dynamics of a scalar field in a regime where the effective potential changes slowly.Given that the Hubble parameter,H,attains a small but non-zero value,we carry out calculations to the first order in H.If we set H=0,all results match those in flat spacetime.Interestingly,we must integrate over the resonances,which in turn leads to an amplification of the effects of a non-zero H.This is an intriguing phenomenon,which cannot be uncovered in flat spacetime.The implications on particle creations in the early universe will be studied in a forthcoming study.     

The mixed conformable partial derivatives

Periodica Mathematica Hungarica - In this paper we introduce a new conformable derivative call it mixed conformable partial derivative, which obeys classical properties, including linearity,...     

A new heuristic approach for the P-median problem

The Euclidean p-median problem is concerned with the decision of the locations for public service centres. Existing methods for the planar Euclidean p-median problems are capable of efficiently solving problems of relatively small scale. This paper proposes two new heuristic algorithms aiming at problems of large scale. Firstly, to reflect the different degrees of proximity to optimality, a new kind of local optimum called level-m optimum is defined. For a level-m optimum of a p-median problem, where m<p, each of its subsets containing m of the p partitions is a global optimum of the corresponding m-median subproblem. Starting from a conventional local optimum, the first new algorithm efficiently improves it to a level-2 optimum by applying an existing exact algorithm for solving the 2-median problem. The second new algorithm further improves it to a level-3 optimum by applying a new exact algorithm for solving the 3-median problem. Comparison based on experimental results confirms that the proposed algorithms are superior to the existing heuristics, especially in terms of solution quality.     

[2+2+1+1] Cycloaddition for de novo Synthesis of Densely Functionalized Phenols

A unique benzannulation strategy for regioselective de novo synthesis of densely functionalized phenols is described. Through metal-mediated formal [2+2+1+1] cycloaddition of two different alkynes and two molecules of CO, a series of densely functionalized phenols were obtained. The benzannulation strategy allows efficient regioselective installation up to five different substituents on a phenol ring. The resulting phenols have a substitution pattern different from those obtained from Dötz and Danheiser benzannulations.     

Reusable optical bioassay platform with permeability-controlled hydrogel pads for selective saccharide detection

A reusable optical bioassay platform using permeability-controlled hydrogel pads for selective saccharide detection has been developed. An optical glucose detection assay based on fluorescence resonance energy transfer (FRET) between dye-labeled dextran and Concanavalin A (ConA) was incorporated into hydrogel pads by entrapment. The hydrogel pads are constructed from hemispherical hydrogel attached onto hydrophobic surfaces of a microtiter plate. The resulted hemispherical hydrogel pads entrapping the sensing biological materials were further surface coated with polyelectrolyte multilayers through a Layer-by-Layer (LbL) self-assembly process to create a permeability-controlled membrane with nanometer thickness. The selective permeable LbL film deposited on the hydrogel surface allows small molecular weight analytes to diffuse into the hydrogel pads while the large molecular weight sensing biological molecules are immobilized. An encapsulation efficiency of 75% for the ConA/Dextran complex within the coated hydrogel pads was achieved and no significant leakage of the complex was observed. Glucose calibration curve with linear range from 0 to 10 mM glucose was obtained. Selective permeability of the hydrogel pads has been demonstrated by measurement of saccharides with various molecular weights. The LbL hydrogel pads could selectively detect monosaccharides (glucose, MW = 180) and disaccharides (sucrose, MW = 342) while polysaccharides (dextran, MW ∼ 70 kDa) cannot diffuse through the LbL layer and are excluded. LbL hydrogel pads allow regeneration of the FRET system with good signal reproducibility of more than 90% to construct a reusable and reagentless optical bioassay platform.     

Monte Carlo simulations of liquid crystals between microstructured substrates

The structure of a model liquid crystalline fluid confined between two microstructured substrates is studied through Monte Carlo simulations. A simple model for a structured substrate, similar in spirit to those used for rough walls of walls with grafted polymers, is introduced. It is found that varying the structure of the substrate, a transition in the alignment of the confined fluid, from parallel to perpendicular, is induced. For particular substrate structures, it is possible to induce tilted alignment in the confined fluid, the tilt angle being temperature dependent.     

Assessment of bone calcium and phosphorus content using micro X‐ray fluorescence spectrometry (μ‐EDXRF): effects of long‐term cadmium poisoning

This study assesses whether the concentrations of biologically important elements in bones are altered by long‐term consumption of cadmium (Cd)‐contaminated water. Heavy metal poisoning has significant impact on humans, and pollutants such as Cd are often found at high concentrations in waterways. Twelve Sprague Dawley rats consumed water with 50 p.p.m. Cd (Cd group), and another 12 consumed normal water (control group). Six subjects from each group were sacrificed after 2 weeks and the others after 4 weeks. Spectra were acquired from the femur by using the EDAX Eagle III micro‐XRF setup, and quantitative calculations were performed by using the fundamental parameter method to determine the concentrations of elements. A bone calcium/phosphorus concentration ratio (Ca/P) of 2.07 ± 0.001 is observed in the spectra from control subjects after 2 weeks and 2.07 ± 0.001 after 4 weeks. In Cd subjects, Ca/P after 2 weeks is 2.04 ± 0.001 and after 4 weeks is 1.97 ± 0.003. Statistically significant differences are obtained when comparing controls with Cd subjects at both time points and when comparing Cd subjects at both time points. Cadmium poisoning significantly affects bone Ca and P concentrations, increasing the likelihood of osteoporosis and other bone diseases. Copyright © 2016 John Wiley & Sons, Ltd.     

The effects of a eutectic modifier on microstructure and surface corrosion behavior of Al-Si hypoeutectic alloys

Hypoeutectic aluminum–silicon alloys can have significant improvements in mechanical properties by inducing structural modification in the normally occurring eutectic. The eutectic modification may affect not only the mechanical properties but also the corrosion resistance of such alloys. It is well known that structural parameters such as grain size and interdendritic spacing can significantly affect corrosion resistance of alloys. However, to date, few researches have been performed to experimentally evaluate the effects of an effective modification of eutectic morphology on surface corrosion behavior of Al–Si alloys. In the present study, modified and unmodified samples of an Al 9 wt.% Si alloy were solidified under similar solidification conditions, and after metallographic procedures, the corrosion resistance was analyzed by both the electrochemical impedance spectroscopy technique and the Tafel extrapolation method carried out in a 0.5 M NaCl test solution at 25 °C. The impedance parameters and corrosion rate were obtained from an equivalent circuit analysis. It was found that the Al-9 wt.% Si alloy casting in the modified condition tends to have its corrosion resistance decreased when compared to the unmodified alloy.     

Direct patterning of composite biocompatible microstructures using microfluidics

This study demonstrates a versatile and fast method for patterning three-dimensional (3D) monolithic microstructures made of multiple (up to 24 demonstrated) types of materials, all spatially aligned, inside a microchannel. This technique uses confocal scanning or conventional fluorescence microscopy to polymerize selected regions of a photocurable material, and microfluidics to automate the delivery of a series of washes and photocurable reagents. Upon completion of lithographic cycles, the aligned 3D microstructures are suitable for microfluidic manipulation and analysis. We demonstrated the fabrication of composite 3D microstructures with various geometries, size scales (up to 1 mm2), spatial resolution (down to 3 microm), and materials. For a typical multi-cycle process, the total fabrication time was tens of minutes, compared to tens of hours for conventional methods. In the case of 3D hydrogels, a potential use is the direct patterning of inhomogeneous 3D microenvironments for studying cell behavior.