Necessary and Sufficient Conditions for Efficiency Via Convexificators

Based on the extended Ljusternik Theorem by Jiménez-Novo, necessary conditions for weak Pareto minimum of multiobjective programming problems involving inequality, equality and set constraints in terms of convexificators are established. Under assumptions on generalized convexity, necessary conditions for weak Pareto minimum become sufficient conditions.     

Applicability of in situ detectors for radiological assessment of strontium-90 in rivers and lakes

Journal of Radioanalytical and Nuclear Chemistry - An in situ detector for radiological assessments of strontium-90 (90Sr) in river and lake water is developed, based on a CaF2(Eu) scintillator,...     

Redox‐responsive core cross‐linked micelles of poly(ethylene oxide)‐b‐poly(furfuryl methacrylate) by Diels‐Alder reaction for doxorubicin release

Redox‐responsive core cross‐linked (CCL) micelles of poly(ethylene oxide)‐b‐poly(furfuryl methacrylate) (PEO‐b‐PFMA) block copolymers were prepared by the Diels‐Alder click‐type reaction. First, the PEO‐b‐PFMA amphiphilic block copolymer was synthesized by the reversible addition‐fragmentation chain transfer polymerization. The hydrophobic blocks of PFMA were employed to encapsulate the doxorubicin (DOX) drug, and they were cross‐linked using dithiobismaleimidoethane at 60 °C without any catalyst. Under physiological circumstance, the CCL micelles demonstrated the enhanced structural stability of the micelles, whereas dissociation of the micelles took place rapidly through the breaking of disulfide bonds in the cross‐linking linkages under reduction environment. The core‐cross‐linked micelles showed fine spherical distribution with hydrodynamic diameter of 68 ± 2.9  nm. The in vitro drug release profiles presented a slight release of DOX at pH 7.4, while a significant release of DOX was observed at pH 5.0 in the presence of 1,4‐dithiothreitol. MTT assays demonstrated that the block copolymer did not have any practically cytotoxicity against the normal HEK293 cell line while DOX‐loaded CCL micelles exhibited a high antitumor activity towards HepG2 cells. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3741–3750     

Influence of elastomeric core–shell impact modifiers on mechanical properties of cellulose diacetate resin

Cellulose diacetate (CDA) plasticized with triacetine was blended by melting extrusion with two different kind of elastomeric core–shell impact modifiers: methyl methacrylate (MMA, shell) grafted onto styrene–butadiene–rubber (SBR, core) (MSBR) and MMA (shell) grafted onto butyl acrylate rubber (BAR, core) (MBAR). The different CDA/MSBR and CDA/MBAR blends were characterized by mechanical properties and morphological observation with various impact modifier contents. The highest impact strength was observed in the case of the blend with 5 wt% of MSBR and 3 wt% of MBAR, respectively. The tensile strength and Young’s modulus of CDA blends were decreased with increasing both MSBR and MBAR. According to SEM observation, MBAR was dispersed more effectively in CDA matrix than that of MSBR, thus indicating improved impact strength.     

Color centres in crystalline Lif films

Abstract

Policrystalline LiF thin films were produced on amorphous substrates at different temperatures. Preliminary optical measurements on F₂ and F₃ ⁺ aggregate color centres produced by electron irradiation were performed.     

Rotational constants of malonaldehyde and isotopic species derived from ab initio results

A quantum mechanical treatment based on ab initio results for the 21-dimensional potential energy surface of malonaldehyde is extended to yield the rotational constants of the lowest two states of the hydrogen transfer motion. The approximate separation of rotation from internal motion by an Eckart type transformation allows one to use a restricted basis set involving not more than one quantum of excitation for the 20 small vibrations. The results agree with experiment on the apparent structural effects of tunnelling excitation and their dependence on isotopic substitution. In the case of asymmetrically substituted species, the extent of localization confirms qualitative estimates from observation. The second moments derived from the rotational constants indicate that the molecular extension is underestimated in the O···O direction and overestimated perpendicular to this direction within the molecular plane. The agreement with experiment is shown to improve significantly by correcting the equilibrium geometry but only marginally by varying further properties of the minimum energy path.     

Oxidation with DMF/HIO4: A Convenient Preparation of Juglone

As part of an ongoing program directed toward the preparation of antraciclinones¹ and aryl substituted lapachones², which are important anticancer and antibiotic³ agents, we became interested in a efficient synthesis of substituted 1,4-naphthoquinones, such as juglone (3). This compound has received some attention due its activity as an allelophatic compound⁴. An extensive analysis of the literature procedures indicated that several methods are available starting from 1,5-dihydroxynaphthalene (1). All the procedures explored the oxidation of carbon four of the naphthyl ring by several known reagents, such as, chromium trioxide-piridine⁵, thallium trinitrate⁵, chromic acid⁶, peracetic acid⁷, dichromate⁸, iron (III) chloride⁹ and mercuric oxide¹⁰. None of the several known methods for the preparation of (3) proceeded in satisfactory yield (except for the thallium trinitrate method which gave 642 yield) and most of them gave a mixture of 1,2 and 1,4-naphthoquinone.     

Photovoltaic devices using semiconducting polymers containing head‐to‐tail‐structured bithiophene,pyrene, and benzothiadiazole derivatives

An alternating copolymer composed of heal‐to‐tail‐structured 3,4′‐dihexyl‐2,2′‐bithiophene (DHBT) and pyrene units [poly(DHBT‐alt‐PYR)] was synthesized using a Stille coupling reaction for use in photovoltaic devices as a p‐type donor. For the reduction of the bandgap energy of poly(DHBT‐alt‐PYR), 4,7‐bis(3′‐hexyl‐2,2′‐bithiophen‐5‐yl)benzo[c][1,2,5]thiadiazole (BHBTBT) units were introduced into the polymer. Poly(DHBT‐co‐PYR‐co‐BHBTBT)s were synthesized using the same polymerization reaction. The synthesized polymers were soluble in common organic solvents and formed smooth thin films after spin casting. The optical bandgap energies of the polymers were obtained from the onset absorption wavelengths. The measured optical bandgap energy of poly(DHBT‐alt‐PYR) was 2.47 eV. As the BHBTBT content in the ter‐polymers increased, the optical bandgap energies of the resulting polymers decreased. The bandgap energies of poly(50DHBT‐co‐40PYR‐co‐10BHBTBT) and poly(50DHBT‐co‐20PYR‐co‐30BHBTBT) were 1.84 and 1.73 eV, respectively. Photovoltaic devices were fabricated with a typical sandwich structure of ITO/PEDOT:PSS/active layer/LiF/Al using the polymers as electron donors and [6,6]‐phenyl C₇₁‐butyric acid methyl ester as the electron acceptor. The device using poly(50DHBT‐co‐20PYR‐co‐30BHBTBT) showed the best performance among the fabricated devices, with an open‐circuit voltage, short‐circuit current, fill factor, and maximum power conversion efficiency of 0.68 V, 5.54 mA/cm², 0.35, and 1.31%, respectively. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Molecular dynamics simulation study on graphene-nanoribbon-resonators tuned by adjusting axial strain

A tunable graphene-nanoribbon (GNR)-resonator was investigated via classical molecular dynamics simulations. Resonance frequencies increased with increasing externally applied gate-force and axial-strain, and could be tuned above several hundred GHz. Tunable resonance frequencies achieved from the gate force were higher than those achieved from the axial-strain. The operating frequencies of GNR-resonators without axial-strain or with small axial-strains were most widely tuned by the gate, and almost linearly increased with increasing mean deflection. As the axial strain increased, the tunable ranges of the GNR-resonators were exponentially decreased, although the operating frequencies increased. GNR-resonators without axial-strain could be applied to wide-range-tuners, whereas GNR-resonators with high axial-strain could be applied to high-frequency-fine-tuners.