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At least 1,333 records · Page 74

Terephthalic Acid Copolyesters Containing Tetramethylcyclobutanediol for High‐Performance Plastics

Abstract There is a need for high‐performance applications for terephthalic acid (TPA) polyesters with high heat resistance, impact toughness, and optical clarity. Bisphenol A (BPA) based polycarbonates and polyarylates have such properties, but BPA is an endocrine disruptor. Therefore, new TPA polyesters that are less hazardous to health and the environment are becoming popular. Tetramethylcyclobutanediol (TMCD) is a difunctional monomer that can be polymerized with TPA and other diols to yield copolyesters with superior properties to conventional TPA polyesters. It has a cyclobutyl ring that makes it more rigid than cyclohexanedimethanol (CHDM) and EG. Thus, TMCD containing TPA copolyesters can have high heat resistance and impact strength. TPA can be made from abundantly available upcycled polyethylene terephthalate (PET). Therefore, this review discusses the synthesis of monomers and copolyesters, the impact of diol composition on material properties, molecular weight, effects of photodegradation, health safety, and substitution of cyclobutane diols for future polyesters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Ion transport in polymerized lyotropic liquid crystals containing ionic liquid

In this work, we investigate the effect of morphology and segmental dynamics on ion transport in polymerized lyotropic liquid crystals (polyLLCs) containing 1-butyl-3-methylimidazolium tetrafluoroborate as ionic liquid (IL). We demonstrate that two important factors, which affect ion conduction in polyLLCs, are grain size and chain density at the interface. The polyLLC with large grain size (70 nm) shows significant reduction in ion conductivity (one order of magnitude) compared to its homopolymer/IL mixture. However, the polyLLC with small grain size (20 nm) has little difference in ion conductivity compared to its homopolymer/IL mixture. It is observed that decreasing the chain density enhances the interaction of IL with polymer chains and consequently slows the relaxation of polymer chains. Finally, in addition, comparing the dynamics of polymer chains in mixtures of homopolymer/IL and templated LLC mesophases shows that the confinement in LLC structure prolongs the relaxation of polymer chains.

36 MATERIALS SCIENCE↗

Evaluation of the Deuterium Isotope Effect in the Detonation of Aluminum Containing Explosives

During or shortly after a detonation in condensed explosives, the reaction rates and the physical mechanism controlling aluminum reaction is poorly understood. We utilize the kinetic isotope effect to probe Al reactions in detonation product gases in aluminized, protonated and deuterated high explosives using high-fidelity detonation velocity and cylinder wall expansion velocity measurements. By observation of the profile of cylinder wall velocity versus time, we are able to determine the timing of aluminum contribution to energy release in product gases and observe the presence or absence of rate changes isotopic substitution. By comparison of the Al oxidation with lithium fluoride (LiF), data indicate that Al oxidation occurs on an extremely fast time scale, with post-detonation kinetic isotope effects observed in carbon containing formulations.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

Measurements of $ \mathrm{t}\overline{\mathrm{t}} $ differential cross sections in proton-proton collisions at $ \sqrt{\mathrm{s}}=13 $ TeV using events containing two leptons

Measurements of differential top quark pair $\mathrm{t\overline{t}}$ cross sections using events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV containing two oppositely charged leptons are presented. The data were recorded by the CMS experiment at the CERN LHC in 2016 and correspond to an integrated luminosity of 35.9 fb$^{-1}$. The differential cross sections are presented as functions of kinematic observables of the top quarks and their decay products, the $\mathrm{t\overline{t}}$ system, and the total number of jets in the event. The differential cross sections are defined both with particle-level objects in a fiducial phase space close to that of the detector acceptance and with parton-level top quarks in the full phase space. All results are compared with standard model predictions from Monte Carlo simulations with next-to-leading-order (NLO) accuracy in quantum chromodynamics (QCD) at matrix-element level interfaced to parton-shower simulations. Where possible, parton-level results are compared to calculations with beyond-NLO precision in QCD. Significant disagreement is observed between data and all predictions for several observables. As a result, the measurements are used to constrain the top quark chromomagnetic dipole moment in an effective field theory framework at NLO in QCD and to extract $\mathrm{t\overline{t}}$ and leptonic charge asymmetries.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Search for bottom-squark pair production with the ATLAS detector in final states containing Higgs bosons, $b$-jets and missing transverse momentum

The result of a search for the pair production of the lightest supersymmetric partner of the bottom quark ($\tilde{b}_1$) using 139 fb -1 of proton-proton data collected at $\sqrt{s}$ = 13 TeV by the ATLAS detector is reported. In the supersymmetric scenarios considered both of the bottom-squarks decay into a b-quark and the second-lightest neutralino, $\tilde{b}_1→b+\tilde{χ}^0_2$. Each $\tilde{χ}^0_2$ is assumed to subsequently decay with 100% branching ratio into a Higgs boson (h) like the one in the Standard Model and the lightest neutralino: $\tilde{χ}^0_2→h+\tilde{χ}^0_1$. The $\tilde{χ}^0_1$ is assumed to be the lightest supersymmetric particle (LSP) and is stable. Two signal mass configurations are targeted: the first has a constant LSP mass of 60 GeV; and the second has a constant mass difference between the $\tilde{χ}^0_2$ and $\tilde{χ}^0_1$ of 130 GeV. The final states considered contain no charged leptons, three or more b-jets, and large missing transverse momentum. No significant excess of events over the Standard Model background expectation is observed in any of the signal regions considered. Limits at the 95% confidence level are placed in the supersymmetric models considered, and bottom-squarks with mass up to 1.5 TeV are excluded.

43 PARTICLE ACCELERATORS↗

Direct determination of cellulosic glucan content in starch-containing samples

A simple and highly selective analytical procedure is presented for the determination of cellulosic glucan content in samples that contain both cellulose and starch. This method eliminates the unacceptably large compounding errors of current two-measurement methods. If both starch and cellulose are present before analytical hydrolysis, both will be hydrolyzed to glucose causing bias and inaccuracy in the method. To prevent this interference, the removal of starch prior to cellulosic quantification is crucial. The method presented here is a concise in-series procedure with minimal measurements, eliminating large compounding errors. Sample preparation consists of a starch extraction employing enzymatic hydrolysis followed by a simple filtration and wash. The samples are then subjected to a two-stage acid hydrolysis. The concentration of glucose is determined by ion exchange high-performance liquid chromatography with a Pb 2+ column and a refractive index detector. The cellulosic glucan content is calculated based on the initial dry weight of the starting material. Data for the native biomass materials studied show excellent reproducibility, with coefficients of variance of 3.0% or less associated with the method. This selectivity for cellulosic glucan by the procedure was validated with several analytical techniques such as liquid chromatography coupled with mass spectrometry (LC–MS), Raman spectroscopy, and nuclear magnetic resonance.

09 BIOMASS FUELS↗

Improved Diffraction Efficiency of Polarization-Sensitive Azobenzene-Containing Copolymers in an Electric Field

Recording media for polarization holography based on new azobenzene-containing monomers with octylmethacrylate are created. Their electrophysical and information properties are investigated. Improvement of the diffraction efficiency of holograms in these media in an external electric field formed by charging the free surface of the polymer film in a corona discharge is demonstrated. The diffraction efficiency is improved more in the copolymer, in which the azobenzene fragments possess larger dipole moments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Thermodynamic Analysis of Prospects for Using Aluminum- and Boron-Containing Clusters in Combined High-Energy Fuels

The high enthalpies of combustion of atomic clusters Al{sub n}, B{sub n}, and C{sub n} (n = 1, 2, …, 7), Al{sub n}C{sub m} and B{sub n}C{sub m} (n = 1, …, 5 and m = 1, …, 5), Al{sub n}B{sub m} (n + m ≤ 7), and Al{sub n}H{sub m} and B{sub n}H{sub m} (n = 1, …, 4 and m ≤ 12) have been assessed. The specific energy release, the final adiabatic temperature, and the effectiveness of the combustion products of fuel mixtures based on kerosene, dimethyl ether, and ethyl alcohol with small additions of such clusters have been determined under the assumption of attaining a thermodynamic equilibrium in their combustion products. An analysis has been made of the potentials of small aluminum- and boron-containing clusters for use in improving thermochemical properties of the fuels. It has been shown that adding such clusters to traditional fuels in the amount of 10% of the fuel mass can increase the specific energy release of the fuel by 2 MJ/kg, the effectiveness of combustion products of the fuel by 10%, and their final temperature by 200 K.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Photophysical Properties of some 1,3,4-Oxadiazole Derivatives Containing Phenolphtalein, Fluorene and Bisphenol A Units

The photophysical properties of the three 1,3,4-oxadiazole derivatives containing fluorene (Ox-FL); fluorene and phenolphtaleine (Ox-FL-FF); or fluorene and bisphenol A (Ox-FL-BPA) moieties in the main chain were investigated by the fluorescence and absorption spectroscopy in different solvents and in the solid state. The electronic absorption spectra included a strong absorption band located in the 270–395 nm region, with a maxima around at 302 nm. The fluorescence excitation spectra were also characterized by one broad band, appearing in the wavelength range of 220–340 nm. All samples displayed the emission bands around 356–373 nm and exhibit high quantum yields ranged from 31.61 to 90.77%, in chloroform solution. The sensitivity of the emission spectra on medium characteristics (polarity, acidity and basicity) were evaluated by using the Catalan solvent scale and the fluorescence titration with a dilute acid solution.

74 ATOMIC AND MOLECULAR PHYSICS↗

Comparison of the Microstructure and Flux Pinning Properties of Polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-d} Containing Zn{sub 0.95}Mn{sub 0.05}O or Al{sub 2}O{sub 3} Nanoparticles

Here we compare the microstructure and flux pinning properties of polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-d} (Y-123 or YBCO) containing either Al{sub 2}O{sub 3} or Zn{sub 0.95}Mn{sub 0.05}O nanoparticles. Samples were prepared using a standard solid-state reaction process, and nanoparticles were added up to a concentration of 0.1 wt%. The crystal structure, microstructure, electrical and magnetic properties were analyzed using X-ray diffraction, scanning electron microscopy and transmission electron microscopy (TEM), and electrical resistivity and DC magnetization measurements, respectively. TEM observations showed that the addition of Zn{sub 0.95}Mn{sub 0.05}O resulted in a high density of fine twins and a variety of interacting microstructures, while Al{sub 2}O{sub 3} addition resulted in a high density of Al-rich nanoscale inhomogeneities embedded in the Y-123 matrix. Flux pinning forces were determined, and predominant pinning mechanisms in the prepared samples were proposed. We evaluated the superconducting properties of YBCO considering the effects of adding insulating or magnetic nanoparticles.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Investigation of Polypropylene-Montmorillonite Clay Nanocomposite Films Containing a Pro-degradant Additive

This paper investigates the performance of polypropylene (PP) incorporated with montmorillonite (MMT) nanoclay, maleic anhydride grafted PP (PP-g-MAH), and pro-degradant additive (TDPA®), which provides additional benefits of increasing biodegradability. A twin-screw extruder was used to compound PP, MMT, PP-g-MAH, and TDPA, and the extruded nanocomposite films were collected for testing, and their mechanical, thermal, barrier, oxo-biodegradability, and morphological properties were evaluated. Tensile test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), oxygen permeability test, soil burial test, X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscope (SEM) analysis were used to investigate these properties. Increasing MMT content from 1 to 3 phr increases tensile strength and Young’s modulus of the neat PP samples up to ca.45% and 27% respectively. Improvement of thermal properties for neat PP samples was observed by increasing MMT content from 1 to 3 phr. However, at 4 phr MMT content, both mechanical and thermal properties of nanocomposites dropped slightly. For soil buried samples, DSC and TGA results revealed significant changes in the thermal properties for PP samples containing TDPE additive compared to neat PP, clearly confirming the effectiveness of this TDPA additive in promoting oxo-biodegradation process of PP. Similarly weight loss evaluation result shows that about 4% weight loss for sample (PP/TD), which is PP and TDPA blend only, compared to neat PP. However, increasing MMT content from 1 to 4 phr slightly reduced weight loss of PP from 3.5 to 1.5%, respectively, for 6 month soil exposure period, which indicates that increasing MMT content was detrimental to the degradation process. For higher MMT content, the oxygen permeability of PP nanocomposites was decreased by 46% of the corresponding values for neat PP. The XRD and TEM results confirmed the exfoliation structure of the nanocomposites. The morphological change after soil burial test was studied using scanning electron microscopy (SEM).

77 NANOSCIENCE AND NANOTECHNOLOGY↗

Vegetable Oil Based Polyurethane Containing 1,2,3-Triazolium Functional Groups as Antimicrobial Wound Dressing

Preparation of antimicrobial polyurethane wound dressing membranes from a mixture of castor oil and a novel soybean oil-based polyol containing 1,2,3-triazolium rings (QTSBO) was described in this research. QTSBO was prepared through N-alkylation of 1,2,3-triazole functional soybean oil (TSBO) with methyl iodide, and TSBO was synthesized from an azidated soybean oil and propargyl alcohol through click reaction. The excellent tensile strength of these dressings under dry state and minimum deterioration of this property at fully hydrated state guaranteed the mechanical protection of wounds during the entire period of the healing process. The measured quantities of equilibrium water absorption and water vapor transmission rate for the optimized dressings confirmed the applicability of the selected formulations for the preservation of proper moist environment over low exuding wounds. The cyto-compatibility of dressings was verified by the excellent ability of the dressings to support the growth and proliferation of dermal fibroblasts. Due to the presence of 1,2,3-triazolium rings the dressing showed efficient antimicrobial activity against different bacterial and fungal stains. Therefore, these dressing could promote wound healing by preserving moist and hygienic environment over the wound bed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Treatment of Fat-Containing Wastewater Using Binary Flocculant Mixtures Based on Chitosan and Quaternary Salt of Poly(2-dimethylamino)ethyl Methacrylate

The flocculating capability of a mixture of chitosan and poly(2-dimethylamino)ethyl methacrylate) methyl sulfate quaternary salt in fat-containing waters was studied. A synergistic effect was determined that involves a significant increase in the degree of clarification and a simultaneous decrease in the fat and organic impurity contents compared with the use of individual flocculants. The prospects of using the studied mixture of similarly charged polyelectrolytes when treating actual sewage from a milk processing plant are described.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Wholly Heterocycles-Based Polyamide–Sulfide Containing Pyridine and Thiazole Rings: A Super-Adsorbent Polymer for Lead Removal

Wholly heterocycles-based polyamide-sulfide (PAS) containing pyridine and thiazole rings with thioether linkage was synthesized and used as a novel adsorbent for lead ion removal from water. The polymer adsorbent was fully characterized via FTIR, NMR and scanning electron microscopy (SEM). The thermal properties of the synthesized polyamide were also studied by thermogravimetric analysis and the outcome showed that the polymer has a good to moderate thermal stability. The SEM was used to investigate the morphology of the wholly heterocycles-based polyamide and the outcomes displayed a porous and globular-like morphology, which guarantee effective metal adsorption. Pb(II) ion removal capacity of the synthesized polymer was studied by varying the contact time and the adsorbent concentration. The maximum removal of Pb(II) was obtained as 99%. Equilibrium behavior and kinetic of the adsorption were also investigated using prevalent isotherm and kinetic models. The adsorption capacity was obtained to be around 714 mg g{sup −1}. The Langmuir isotherm and the pseudo-second order kinetic model suggested superior agreement with the equilibrium and kinetic adsorption data, respectively. Generally, the results of this research demonstrated that the synthesized polymer is a super-adsorbent for heavy metal removal from water.

36 MATERIALS SCIENCE↗

Correction to: Treatment of Fat-Containing Wastewater Using Binary Flocculant Mixtures Based on Chitosan and Quaternary Salt of Poly(2-dimethylamino)ethyl Methacrylate

The original version of this article unfortunately contained an error in the article title of Ref. [22]. The correct reference is given below: Bigogno RG, Rodríguez RJS, Abreu MF (2018) Quaternized chitosan for ecological treatment of bauxite mining effluents. J Polym Environ 26:4169.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Viscoelastic Stresses in the Plates Containing Inclusions with Cracks

We study viscoelastic stresses in the plates containing inclusions weakened by cracks by the method of boundary integral equations and the Laplace integral transformation. The case in which the rheological relations between stresses and strains are written in the differential form is analyzed in detail. To solve the boundary problem of viscoelasticity, we use the well-known approach in which the corresponding problem of the theory of elasticity is studied by replacing the differential operators with constant quantities. The solution of the auxiliary problem is obtained by the method of boundary integral equations reduced to a system of algebraic equations. After replacing the elastic quantities in this system by the corresponding differential operators, we solve the system obtained as a result by using the Laplace integral transformation and then applying the improved numerical-analytic inversion formula adapted to this class of problems.

36 MATERIALS SCIENCE↗

Reflection and transmission of electromagnetic waves by a multilayered solar cell containing organic materials

Light trapping or absorption is a key concept for design and fabricating solar cells. The propagation of electromagnetic waves through a multilayered solar cell containing organic materials has theoretically investigated. In particular, the reflected, transmitted, and absorbed powers are found and defined. The main parameters of the structure and the required equations for TE polarization are presented in detail. The boundary conditions of the electric and magnetic fields of the incident waves are imposed at each interface and Snell’s law is applied. Expressions for the overall reflection and transmission coefficients are provided by a recursive method. The reflected, transmitted, and absorbed powers are determined using these coefficients. In the numerical results, the mentioned powers are computed and illustrated as a function of the angle of incidence, the wavelength, and the thickness of the active layer when the extinction coefficient of the active layer changes.

14 SOLAR ENERGY↗

Optomechanical control of mode conversion in a hybrid semiconductor microcavity containing a quantum dot

The future of quantum communication systems and quantum networks heavily rely on the ability to fabricate and coherently control the conversion of photons between different modes based on a solid-state plateform. In this work, we propose and theoretically investigate a scheme to optomechanically control coherent mode conversion of optical photons by utilizing two optically coupled hybrid semiconductor microcavities containing a quantum dot (QD). One of the microcavity is pumped by an external laser and the second cavity is driven by light emitted by the QD that is embedded in the interface separating the two microcavities. The semiconductor microcavities can be fabricated using distributed Bragg reflectors and can be made movable. We have demonstrated that photon-mode-conversion efficiency can be coherently manipulated by the optomechanical mode under appropriate conditions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗