Reactivities of mixed organozinc and mixed organocopper reagents. Part 13 Kinetic study for phosphine‐catalyzed acylation of alkylarylzincs and effect of residual group on the transfer rate of alkyl group

Kinetics of reactions of di‐n‐butylzinc, n‐Bu₂Zn, and mixed n‐butyl(substituted phenyl)zinc reagents and n‐Bu(functional group (FG)?C₆H₄)Zn with benzoyl chloride in the presence of tri‐n‐butylphosphine have been investigated. Reaction rates of transferable n‐butyl group have been determined in tetrahydrofuran at 0 °C to compare the transfer rate of n‐butyl group in homo and mixed diorganozincs. Rate law is consistent with a third‐order reaction, which is first order in diorganozinc, benzoyl chloride, and n‐Bu₃P, and a mechanism was proposed. The lower reaction rate of n‐BuPhZn than that of n‐Bu₂Zn and negative reaction constant in Hammett plot are in accordance with the carbanionic charge of transferable n‐butyl group in the acylation reaction. These findings support the hypothesis that the reaction rate of transferable group, R_T, changes depending upon the residual group, R_R, in R_RR_TZn reagents. Copyright © 2016 John Wiley & Sons, Ltd.     

Langmuir-Blodgett self-assembly and electrochemical catalytic property of FePt magnetic nano-monolayer

Dispersed-well FePt nanoparticles with particle size ~5 nm have been prepared by hydrazine hydrate reduction of H₂PtCl₆·6H₂O and FeCl₂·4H₂O in ethanol–water system. By employing as-synthesized FePt nanoparticles, the monolayer can be formed by LB Technique. The structural, magnetic properties and electrochemical properties of FePt monolayer were respectively studied by XRD, TEM, VSM and CHI 820 electrochemical workstation. The as-synthesized particle has a chemically disordered fcc structure and can be transformed into chemically ordered fct structure after annealing treatment above 400°C. The coercivity of ordered fct FePt phase can be up to 2515Oe. CVs of 0.5 M H₂SO₄/0.5M CH₃OH on GCE modified with FePt nanoparticles monolayer films illustrate that the as-synthesized FePt is a kind of active electrochemical catalyst.     

荧光显微镜研究极端pH值诱导磷脂支撑膜的侧向再组织

利用荧光显微镜研究了极端pH值诱导支撑磷脂双层膜的侧向再组织.结果表明,在强酸/强碱性溶液中,流动性较好的二油酰磷脂酰胆碱支撑膜出现破裂、分离、出芽或生出微管等与细胞内吞和外排相似的现象.基于极性分子与H+/H3O+或OH-的相互作用,以电中性的磷脂首基为核吸附溶液中的H+/H3O+或OH-.当磷脂膜上下叶吸附的电荷量不同时,引起两叶有效面积差,即磷脂膜曲率不对称,从而诱发磷脂膜出现各种结构和动力学的响应.本研究有助于理解极端环境对生物膜的影响,为研究生物膜的形变过程提供了参考.     

In situ device for salinity measurements (chloride detection) of ocean surface

Microbend sodium chloride sensors based on polymer swelling are the latest approach to fiberoptic sodium chloride sensors. We have designed, constructed, and tested a compact microbend fiberoptic sodium chloride sensor that utilizes microbend and polymer swelling effects through the use of modified polymer beads. The design of this sensor is an improvement over previously reported microbend sensors. This sodium chloride sensor has shown feasibility as a practical, stable, inexpensive device with excellent performance and most of the desirable sensor properties including reversibility. Further optimization of the sensor is possible for the various applications we envision.     

Polymer assisted assembling of the semiconductor particles: Structural and electrical studies

CdS and Si semiconductor nanopraticles were embedded in a polymer matrix and characterized using various techniques. The surface properties and size distribution of the nanoparticles were monitored by POM and SEM and found to be uniform but around the crystalline frameworks of the polymer. XRD and FTIR analysis have been used to ensure the composite nature and particle size of the semiconductor loaded films. The electrical conductivity of these films were evaluated and found to increase with semiconductor dispersion and attains a percolation threshold at optimum composition. This composition and the distribution of the clusters is shown to vary with the type of the semiconductor, i.e., CdS or Si.     

FTIR spectra of plasticized high molecular weight PVC–LiCF3SO3 electrolytes

Fourier transform infrared spectroscopy studies have been conducted to investigate the interaction among components in a system of high molecular weight polyvinylchloride (PVC)–lithium trifluoromethanesulfonate (LiCF₃SO₃) incorporated with different type of plasticizers, namely, ethylene carbonate (EC), propylene carbonate (PC), and dibutylphthalate (DBP). Interaction between PVC and LiCF₃SO₃ was confirmed by C–H rocking mode at 1,255 cm⁻¹ for PVC shift to 1,252 cm⁻¹ in PVC–LiCF₃SO₃. The plasticizers’ carbonyl (C=O) oxygen atom which carries lone pair electrons interact with Li⁺ of LiCF₃SO₃ and methine hydrogen of PVC in LiCF₃SO₃–plasticizer system and PVC–plasticizer system, respectively. Changes in peaks assigned to 1,264 cm⁻¹ (ν _as(SO₃)), 1,033 cm⁻¹ (ν _s(SO₃)), 1,181 cm⁻¹ (ν _as(CF₃)), 1,230 cm⁻¹ (ν _s(CF₃)), 765 cm⁻¹ (δ _s(CF₃)), 644 cm⁻¹ (δ _s(SO₃)), 578 cm⁻¹ (δ _as(CF₃)), and 519 cm⁻¹ (δ _as(SO₃)) indicate the occurrence of complexation in the PVC–LiCF₃SO₃ system, LiCF₃SO₃–plasticizer system, and PVC–LiCF₃SO₃–plasticizer system.     

Propagators in polymer quantum mechanics

Polymer Quantum Mechanics is based on some of the techniques used in the loop quantization of gravity that are adapted to describe systems possessing a finite number of degrees of freedom. It has been used in two ways: on one hand it has been used to represent some aspects of the loop quantization in a simpler context, and, on the other, it has been applied to each of the infinite mechanical modes of other systems. Indeed, this polymer approach was recently implemented for the free scalar field propagator. In this work we compute the polymer propagators of the free particle and a particle in a box; amusingly, just as in the non polymeric case, the one of the particle in a box may be computed also from that of the free particle using the method of images. We verify the propagators hereby obtained satisfy standard properties such as: consistency with initial conditions, composition and Green’s function character. Furthermore they are also shown to reduce to the usual Schrödinger propagators in the limit of small parameter μ₀${\mu }_0$, the length scale introduced in the polymer dynamics and which plays a role analog of that of Planck length in Quantum Gravity.     

Gold coatings on polyethyleneterephthalate nano-patterned by F2 laser irradiation

In this work we present periodic surface structures generated by linearly polarized F₂ laser light (157 nm) on polyethyleneterephthalate (PET). Atomic force microscopy was used to study the topological changes induced by the laser irradiation. The laser irradiation induces the formation of periodic ripple structures with a width of ca 130 nm and a height of about 15 nm in the fluence range 3.80-4.70 mJ/cm² and the roughness of the polymer surface increases due to the presence of these periodic structures. Subsequently, the laser modified PET foils were coated with a 50 nm thick gold layer by sputtering. After Au deposition on the PET foils with ripple structure, the roughness of surface decreases in comparison to PET with ripples without Au coating. For 50 nm thick Au layers, the ripple structure is not directly transferred to the gold coating, but it has an obvious effect on the grain size of the coating. With considerably thinner Au layers, the ripple structures are smoothened but preserved.     

Polymer adsorption on the surface of highly dispersed silica

Attempts at modification of silica surface with a polymer (natural latex) directly in the course of the precipitation process have been made. The effects of temperature, non-ionic surfactants and silane coupling agent in preparation of poly[cis-isoprene]-coated silica on the precipitation of polymer/silica composites initiated by ammonium salts (NH₄Cl, (NH₄)₂SO₄, NH₄HCO₃), have been studied. The influence of the process parameters on the quality of the silicas obtained and the character of the polymer adsorption on the silica surface has been determined along with the effect of the surface impregnation with natural latex on physicochemical parameters of the silicas (bulk density, capacities to absorb water, dibutyl phthalate and paraffin oil) and their surface structure.     

Blended polyethylene terephthalate and polyethylene naphthalate polymers for scintillation base substrates

Polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are both good candidates for use as scintillation base substrates. One advantage is their relatively high density of 1.33 g cm⁻³. To enhance their relative strengths and to mitigate their weaknesses, we blended PET and PEN 1:1 by weight and found that the overall characteristics are improved. The wavelength at maximum emission was 415 nm, the refractive index was 1.61, and the light yield was 0.85 times that of PEN. These results increase the available options for base materials to be used as scintillators.