Melt spinning and drawing of 2‐methyl‐1,3‐propanediol‐substituted poly(ethylene terephthalate)

The structure and properties of fibers prepared from copolymers of poly(ethylene terephthalate) (PET) in which 2‐methyl‐1,3‐propanediol (MPDiol® Glycol is a registered trademark of Lyondell Chemical Company) at 4, 7, 10, and 25 mol% was substituted for ethylene glycol were studied and compared with those of PET homopolymer. Filaments were melt spun over a range of spinning conditions, and some filaments that were spun at relatively low spinning speeds were subjected to hot drawing. The filaments were characterized by measurements of birefringence, differential scanning calorimetry (DSC) crystallinity, melting point, glass transition temperature, wide‐angle X‐ray diffraction patterns, boiling water shrinkage, tenacity, and elongation to break. Filaments containing 25 mol% MPDiol did not crystallize in the spinline at any spinning speed investigated, whereas the other resins did crystallize in the spinline at high spinning speeds. However, compared with PET homopolymer, increasing substitution of MPDiol reduced the rate at which the crystallinity of the melt spun filaments increased with spinning speed and reduced the ultimate crystallinity that could be achieved by high‐speed spinning. The rate of development of molecular orientation, as measured by birefringence, also decreased somewhat with increasing MPDiol content. Shrinkage in boiling water decreased at high spinning speeds as the amount of crystallinity increased; however, the shrinkage decreased more slowly with increase in spinning speed as MPDiol content increased. Tenacity also decreased slightly at any given spinning speed as MPDiol content increased, but there was no significant effect on elongation to break. The addition of MPDiol in amounts up to 7 mol% increased the maximum take‐up velocity that could be achieved at a given mass throughput. This result indicates that the use of higher spinning speeds could potentially increase the productivity of melt spun yarns. Copolymer filaments spun at low speeds were readily drawn to produce highly oriented fibers with slightly less birefringence, crystallinity, and tenacity than similarly processed PET homopolymer. Preliminary dyeing experiments showed that the incorporation of MPDiol improved the dyeability of the filaments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2598–2606, 2003     

Gamma‐ray irradiation effect of polyethylene on dimaleimides as a class of new multifunctional monomers

Multifunctional monomers, m‐xylylenedimaleimide, p‐phenylenedimaleimide, m‐phenylenedimaleimide, and p‐phenylenedinadimide, all of which have maleimide groups, were synthesized to increase thermal and radiation stabilities. The synthesized multifunctional monomers showed good compatibility with low‐density polyethylene (LDPE). Mixtures of LDPE and these multifunctional monomers were irradiated with γ‐rays from a Co‐60 source at room temperature in a nitrogen atmosphere. The absorbed dose ranged from 0 to 160 KGy. Among these multifunctional monomers, m‐xylylenedimaleimide was the best in gel fraction enhancement. Crosslinked LDPE with m‐xylylenedimaleimide displayed a higher modulus than that of crosslinked LDPE with triallyl cyanurate. For the elongation property, LDPE with m‐xylylenedimaleimide as a multifunctional monomer showed better results than that with commercial multifunctional monomers such as triallyl cyanurate (TAC) and trimethylol propane triacrylate (TMPTA). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2339–2345, 2003     

Synthesis of silver/polymer colloidal composites from surface-functional porous polymer microspheres

This study presents a different colloidal silver (Ag)/polymer system where Ag nanoparticles are deposited uniformly onto surface-functional porous poly(ethylene glycol dimethacrylate-co-acrylonitrile) (poly(EGDMA-co-AN)) microspheres. The formation and morphology of the composite microspheres were characterized from electron microscopy and X-ray diffraction analyses. The significance of the present report is that owing to the high affinity between Ag and nitrile group (CN) on the large surface of the microspheres, the Ag nanoparticles having a face-centered cubic phase were incorporated evenly into the deep pores of the microspheres with fine size and size distribution. In the preservation test, the Ag/poly(EGDMA-co-AN) composite microspheres obtained showed an excellent anti-bacterial performance, elucidating a high applicability for a new preservative.     

Synthesis of a new conjugated polymer based on benzimidazole and its sensory properties using the fluorescence‐quenching effect

A new anionic conjugated polymer containing a fluorene group in the main chain was designed and synthesized from poly(2,7‐(9,9′‐dihexylfluorene)‐5,5′‐bibenzimidazole) (PFBI). The polymer showed strong blue emission with high quantum efficiency (0.64) at 450 nm in MeOH and the dramatic quenching effect by Methyl Viologen (MV²⁺). The fluorescence‐quenching effect results from the weak complex formation between an anionic polymer and electron acceptors such as bipyridinium derivatives. The linear Stern–Volmer constant (K_sv) was 3.7×10⁵ M^?1 for MV²⁺. The newly synthesized polymer is expected to show the applicability for biological and chemical sensors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 900–904, 2004     

Molecular aspects of the transport and toxicity of ochratoxin a

Ochratoxins are a class of naturally occurring compounds produced by several fungi. The most toxic is ochratoxin A (OTA), and occurrence of some human nephropathies and tumors correlate with enhanced OTA exposure. In this Account, the following areas are examined: molecular details of the binding of OTA to human serum albumin (HSA), the influences of binding to HSA on the trans-port of OTA across epithelial cell membranes by organic anion transport proteins, the oxidative activation of OTA, and the formation of OTA adducts with biological molecules. These studies are beginning to provide a detailed chemical model for the trans-port, accumulation, and genotoxic and carcinogenic effects of OTA.     

Photocatalytic,magnetic, and electrochemical properties of La doped BiFeO3 nanoparticles

We successfully prepared La_1?xBi_xFeO₃ (L_xB_1?xFO, x?=?0.01–0.1) nanoparticles using a sol-gel technique, and studied their photocatalytic, magnetic, and electrochemical properties. Structural refinement studies of the prepared nanoparticles revealed a gradual structural transition from rhombohedral to orthorhombic. The average grain size was observed to decrease with increasing the concentration of La. The photocatalytic degradation of Rhodamine B (RhB) in the presence of the prepared nanoparticles was studied under visible light irradiation. The L_0.06B_0.94FO nanoparticles showed higher degradation efficiency compared to pure BiFeO₃ (BFO) nanoparticles. Magnetic studies showed that La doping improved the magnetization of BFO due to the reduction in grain size and destruction of cycloid coupling of spins. Higher specific capacitance values were obtained for La doped BFO (LBFO) nanoparticles compared to BFO nanoparticles. A maximum specific capacitance of 219?F?g^?1 was obtained at a current density of 1?A?g^?1 for LBFO nanoparticles.     

Synthesis of a new polyarylenvinylene derivative based on a terstyryl group linked by a maleimide group

Summary The new polyarylenevinylene, structurally based on a terstyryl group linked by a maleimide group, was prepared from a new dibrominated diphenylmaleimide monomer and p-divinylbenzene by Heck-type Pd catalyzed polycondensation. The polymer was soluble in common organic solvents and had M _w and the polydispersity index of 73,600 g/mol and 5.0, respectively. Analysis with IR and NMR indicated that the polymer had a stereoregular vinylene sequence in the backbone of Z, E, E-configurations in series. The polymer showed optical absorption maximums at 353 nm and 444 nm and the bright orange red-colored photoluminescence at 570 nm in a solution and 590 nm in a film. Received: 19 September 2000/Revised version: 4 December 2000/Accepted: 11 December 2000     

A prioritization method for replacement of water mains using rank aggregation

Pipe breaks in municipal water distribution networks may cause serious damage economically and socially. Existing methods for replacement scheduling of pipes do not provide practical indicators for replacing an individual deteriorated pipe. This work formulates the selection problem as the decision of preference ordering or ranking and proposes a bipartite ranking-based approach. The suggested approach also considers loss from broken pipes in terms of the costs associated with broken water main and its repair. We use rank aggregation method to integrate multiple ranks into replacement order of water mains. The suggested framework prioritizes current pipe sections for replacement based on the aggregated ranks. Multiple ranks given by the reliability of water pipe sections are aggregated and a cost effective policy for pipe replacement is derived.     

Low Thermal Inertia Molding (LTIM)

Injection molding is one of the most commonly used methods of processing polymers. The process allows rapid, automated production of a wide variety of complicated, three-dimensional parts in large production volumes. The process is capable of producing compound curvatures, snaps, hinges, bosses, threaded holes, gear teeth, and many other features. With proper design, these complex parts can be produced in a single molding operation.     

Loss of Fat with Increased Adipose Triglyceride Lipase-Mediated Lipolysis in Adipose Tissue During Laying Stages in Quail

The goal of the current study was to investigate regulation of key genes involved in lipid metabolism in adipose and liver to relate lipolytic and lipogenic capacities with physiological changes at the pre-laying, onset of laying, and actively laying stages of quail. Followed by a 50 % increase from pre-laying to onset of laying, adipose to body weight ratio was significantly reduced by 60 % from the onset of laying to the actively laying stage (P < 0.05), mainly resulting from the significantly increased adipocyte size from the pre-laying stage to the onset of laying and reduction of adipocyte size from the onset of laying to the actively laying stage (P < 0.05). In the adipose tissue of actively laying quail, increased protein expression and phosphorylation of adipose triglyceride lipase (ATGL) together with an elevated mRNA expression of comparative gene identification-58, an activator of ATGL, contributes to increased lipolytic activity, as proved by increased amounts of plasma non-esterified fatty acid (P < 0.05). In addition, decreased mRNA expression of fatty acid transport protein in the actively laying quail could contribute to the adipocyte hypotrophy (P < 0.05). In the liver, relative mRNA expression of apo-very low density lipoprotein (VLDL)-II increased significantly from the pre-laying to actively laying stages (P < 0.05), indicating increased apoVLDL-II actively facilitated VLDL secretion in the actively laying quail. These results suggest that the laying birds undergo active lipolysis in the adipocyte, and increase VLDL secretion from the liver in order to secure a lipid supply for yolk maturation.