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.     

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     

A simulation-based genetic algorithm approach for reducing emissions from import container pick-up operation at container terminal

Emissions from idle truck engines are a main source of pollution at container terminals. In this study, we focus on reducing such emission from waiting trucks as well as the related crane operations with a new truck arrival control method that gives individual truck limited time slots for entry. We develop a method to optimize the time slot assignment for individual trucks, aiming at minimizing total emissions from trucks and cranes at import yards. The method applies discrete event simulation to estimate total truck waiting times and crane moving distance, and then applies a genetic algorithm to minimize the generated emissions from these trucks and cranes. The experiment result shows that the truck arrivals should be controlled based on the stacking of import containers, and that such control is necessary for reducing truck idling emissions at a congested container terminal.     

Organic Positive Materials for Magnesium Batteries: A Review

Magnesium batteries, like lithium-ion batteries, with higher abundance and similar efficiency, have drawn great interest for large-scale applications such as electric vehicles, grid energy storage and many more. On the other hand, the use of organic electrode materials allows high energy-performance, metal-free, environmentally friendly, versatile, lightweight, and economically efficient magnesium storage devices. In particular, the structural diversity and the simple activity of organic molecules make redox properties, and hence battery efficiency, easy to monitor. While organic magnesium batteries still in their infancy, this field becomes more and more promising because significant results were reported. To summarize the achievements in studies on organic cathodes for magnesium systems, their synthesis is discussed, combined with electrode design to provide the basis for controlling the electrochemical properties. Moreover, the techniques to synthesize organic materials with high-yield are mentioned. Finally, potential problems and prospects are explored to further improve organic cathodes.     

A new dimeric alkylresorcinol from the stem barks of Swintonia floribunda (Anacardiaceae)

From an EtOAc-soluble fraction of the stem barks of Swintonia floribunda (Anacardiaceae), one new dimeric alkylresorcinol named integracin E (1), together with 4 known compounds (2–5) were isolated. Their chemical structures were elucidated based on the spectroscopic data interpretation. The absolute configuration of 1 was determined by the specific rotation analysis of its acid-catalyzed hydrolysis product. Compound 1 showed potent tyrosinase inhibitory activity with an IC₅₀ value of 48.2?μM.