Mediastinal parathyroid adenoma detected by 99mTc-methoxyisobutylisonitrile: report of a case

In a randomized controlled clinical trial, 14 patients requiring resection of tumors were divided in two groups: one group was anesthetized with nitrous oxide [67% N2O-33% O2 (vol/vol)] and the other with propofol. Two other groups of subjects were studied: a group of patients that was undergoing orthopedic procedures and was anesthetized with nitrous oxide [67% N2O-33% O2 (vol/vol)] and a control group (fasted for 10 hrs and no anesthesia). In patients requiring resection of tumors, the blood L-methionine concentration was significantly lower and the blood amino acid pattern was significantly affected after the administration of nitrous oxide (120-310 mins) compared with values after the induction of anesthesia and before surgery. The administration of propofol (120-240 mins) did not produce any of these changes. No patients required blood transfusion during surgery, and the patients had not previously been treated with cancer chemotherapeutic agents. The administration of nitrous oxide (60-150 mins) to patients undergoing orthopedic procedures did not affect blood L-methionine. It is concluded that the administration of nitrous oxide to cancer-bearing patients, but not to those undergoing orthopedic surgery, produced major changes in amino acid metabolism; therefore, consideration should be given to the avoidance of exposure of cancer patients to nitrous oxide.     

Catalytic synthesis and characterization of an alternating copolymer from carbon dioxide and propylene oxide using zinc pimelate

New zinc pimelate catalysts used for copolymerization of carbon dioxide and propylene oxide have been synthesized in high yield by a magnetic stirring method. The regular molecular structure of the zinc pimelate was confirmed by Fourier‐transform infrared spectroscopy and wide‐angle X‐ray diffraction techniques. Accordingly, poly(propylene carbonate) (PPC) can be synthesized from carbon dioxide and propylene oxide using these zinc pimelate catalysts. High catalytic efficiency (95.2 gram polymer per gram catalyst or 21 300 g of polymer per mole of zinc) was achieved by optimizing the PO/catalyst ratio. NMR measurement revealed that the PPC synthesized had an alternating copolymer structure. The thermal properties of PPC were determined by modulated differential scanning calorimetry and thermogravimetric analysis. The results demonstrated that the PPC copolymer exhibited an extremely high glass transition temperature of 44.27 °C and decomposition temperature of 257 °C, comparable with values reported in literature. Copyright © 2003 Society of Chemical Industry     

tert-Butyl Hydroperoxide (tBHP)-Induced Lipid Peroxidation and Embryonic Defects Resemble Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency in C. elegans

G6PD is required for embryonic development in animals, as severe G6PD deficiency is lethal to mice, zebrafish and nematode. Lipid peroxidation is linked to membrane-associated embryonic defects in Caenorhabditis elegans (C. elegans). However, the direct link between lipid peroxidation and embryonic lethality has not been established. The aim of this study was to delineate the role of lipid peroxidation in gspd-1-knockdown (ortholog of g6pd) C. elegans during reproduction. tert-butyl hydroperoxide (tBHP) was used as an exogenous inducer. Short-term tBHP administration reduced brood size and enhanced germ cell death in C. elegans. The altered phenotypes caused by tBHP resembled GSPD-1 deficiency in C. elegans. Mechanistically, tBHP-induced malondialdehyde (MDA) production and stimulated calcium-independent phospholipase A₂ (iPLA) activity, leading to disturbed oogenesis and embryogenesis. The current study provides strong evidence to support the notion that enhanced lipid peroxidation in G6PD deficiency promotes death of germ cells and impairs embryogenesis in C. elegans.     

Mass,Mobility, Volatility,and Morphology of Soot Particles Generated by a McKenna and Inverted Burner

Particle mass, mobility, volatile mass fraction, effective density, mass concentration, mass–mobility exponent, and particle morphology were measured from soot generated from a premixed flame (McKenna burner) and an inverted diffusion flame over a range of equivalence ratios. It was found that the mass fraction of volatile material on the soot from the McKenna burner could be up to 0.83 at a high equivalence ratio, but there was no measurable volatile material on the soot from the inverted burner. The inverted burner can produce soot at different mass–mobility exponents, ranging from 2.23 to 2.54, over a range of global equivalence ratios of 0.53–0.67, while the mass–mobility exponent ranges from 2.19 to 2.99 for fresh soot and 2.19 to 2.81 for denuded soot for the McKenna burner at equivalence ratios of 2.0–3.75. Transmission electron microscopy analysis of inverted burner soot shows that a range of particle morphologies is present at a given global equivalence ratio, likely due to different local equivalence ratios and flame conditions in the diffusion flame. Primary particle diameter tends to increase with aggregate size, which could contribute to the mass–mobility exponent being well above 2.

Copyright 2013 American Association for Aerosol Research     

Effect of Alkyl Phenol from Cashew Nutshell Liquid and Sisal Fiber Reinforcement on Dry Sliding Wear Behavior of Epoxy Resin

A phenalkamine made from the reaction of alkyl phenol from cashew nut shell liquid (CNSL) and alkaylamine was added at three different weight percentages (30%, 40%, and 50%) as a hardener for curing the epoxy polymer. The effect of phenalkamine concentrtation on mechanical and dry sliding wear resistance properties were compared to synthetic aliphatic amine (TETA) cured epoxy network. It was obsererved that incorporation of phenalkamine improves the dry sliding wear resistance property of the epoxy network along with the impact strength and elongation properties. Epoxy composites incorporating sisal fiber placed unidirectionally (either parallel, anti-parallel, or perpendicular to the sliding direction) were prepared in a vacuum infusion process using phenalkamine as a crosslinking agent. It was observered that wear resistance of longitudinally oriented fibers composite was found to be higher owing to the area of fibers exposed to sliding asperities being smaller. With the goal to understand the brittleness behavior of epoxy networks, fractured surfaces of the epoxy networks were analyzed using optical microscope. A correlation was found between the mechanical and wear resistance properties of the epoxy networks.     

Cellulose-based Antimicrobial Composites and Applications: A Brief Review

Cellulose-based antimicrobial composites, typically in the form of functional films and cloth, have received much attention in various applications, such as food, medical and textile industries. Cellulose is a natural polymer, and is highly biodegradable, green, and sustainable. Imparting antimicrobial properties to cellulose, will significantly enhance its applications so that its commercial value can be boosted. In this review paper, the use of cellulose for antimicrobial composites’ preparation was discussed. Two different approaches: surface loading/coating and interior embedding, were focused. Three most widely-applied sectors: food, medical and textile industries, were highlighted. Nanocellulose, as a leading-edge cellulose material, its unique application on the antimicrobial composites, was particularly discussed.     

Auger and A–C impedance studies of the R–F sputter deposited Fe2O3 films

Thin iron oxide films were prepared by r–f sputtering techniques. X-ray diffraction and Auger electron spectoscopic techniques were used to determine the structure of the films. The results showed that the film prepared with such techniques has an α-Fe₂O₃ structure. A–C impedance techniques were also applied to determine the electrochemical properties of the films. It was found that the flim exhibited semiconducting properties in the borate buffer solution at the anodic potentials below 0.73 V vs. R.H.E.     

Novel Nanoparticle‐Reinforced Metal Matrix Composites with Enhanced Mechanical Properties

This paper summarizes and reviews the state‐of‐the‐art processing methods, structures and mechanical properties of the metal matrix composites reinforced with ceramic nanoparticles. The metal matrices of nanocomposites involved include aluminum and magnesium. The processing approaches for nanocomposites can be classified into ex‐situ and in‐situ synthesis routes. The ex‐situ ceramic nanoparticles are prone to cluster during composite processing and the properties of materials are lower than the theoretical values. Despite the fact of clustering, ex‐situ nanocomposites reinforced with very low loading levels of nanoparticles exhibit higher yield strength and creep resistance than their microcomposite counterparts filled with much higher particulate content. Better dispersion of ceramic nanoparticles in metal matrix can be achieved by using appropriate processing techniques. Consequently, improvements in both the mechanical strength and ductility can be obtained readily in aluminum or magnesium by adding ceramic nanoparticles. Similar beneficial enhancements in mechanical properties are observed for the nanocomposites reinforced with in‐situ nanoparticles.     

In‐situ reinforcement of PBT/ABS blends with liquid crystalline polymer

Ternary in‐situ poly(butylene terephthalate) (PBT)/poly(acrylonitrile‐butadienestyrene) (ABS)/liquid crystalline polymer(LCP) blends were prepared by injection molding. The LCP used was a versatile Vectra A950, and the matrix material was PBT/ABS 60/40 by weight. Maleic anhydride (MA) copolymer and solid epoxy resin (bisphenol type‐A) were used as compatibilizers for these blends. The tensile, dynamic mechanical, impact, morphology and thermal properties of the blends were studied. Tensile tests showed that the tensile stregth of PBT/ABS/LCP blend in the longitudinal direction increased markedly with increasing LCP content. However, it decreased sharply with increasing LCP content up to 5 wt%; thereafter it decreased slowly with increasing LCP content in the transverse direction. The modulus of this blend in the longitudinal direction appeared to increase considerably with increasing LCP content, whereas the incorporation of LCP into PBT/ABS blends had little effect on the modulus in the transverse direction. The impact tests revealed that the Izod impact strength of the blends in longitudinal direction decreased with increasing LCP content up to 10 wt%; thereafter it increased slowly with increasing LCP. Dynamic mechanical analyses (DMA) and thermogravimetric measurements showed that the heat resistance and heat stability of the blends tended to increase with increasing LCP content. SEM observation, DMA, and tensile measurement indicated that the additions of epoxy and MA copolymer to PBT/ABS matrix appeared to enhance the compatibility between PBT/ABS and LCP.     

Study on in situ reinforcing and toughening of a semiflexible thermotropic copolyesteramide in PBT/PA66 blends

Ternary in situ composites based on poly(butylene terephthalate) (PBT), polyamide 66 (PA66), and semixflexible liquid crystalline polymer (LCP) were systematically investigated. The LCP used was an ABA30/PET liquid crystalline copolyesteramide based on 30 mol % of p‐aminobenzoic acid (ABA) and 70 mol % of poly(ethylene terephthalate) (PET). The specimens for thermal and rheological measurements were prepared by batch mixing, while samples for mechanical tests were prepared by injection molding. The results showed that the melting temperatures of the PBT and PA66 phases tend to decrease with increasing LCP addition. They also shifted toward each other due to the compatibilization of the LCP. The torque measurements showed that the ternary blends exhibited an apparent maximum near 2.5–5 wt % LCP. Thereafter, the viscosity of the blends decreased dramatically at higher LCP concentrations. Furthermore, the torque curves versus the PA66 composition showed that the binary PBT/PA66 blends can be classified as negative deviation blends (NDBs). The PBT/PA66/LCP blends containing up to 15 wt % LCP were termed as positive deviation blends (PDBs), while the blends with the LCP ≥25 wt % exhibited an NDB behavior. Finally, the tensile tests showed that the stiffness and tensile strength of ternary in situ composites were generally improved with increasing LCP content. The impact strength of ternary composites initially increased by the LCP addition, then deteriorated when the LCP content was higher than 10 wt %. The correlation between the mechanical properties and morphology of the blends is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1975–1988, 2000