Electrospun composite poly(lactic acid)/polyaniline nanofibers from low concentrations in CHCl3: Making a biocompatible polyester electro-active

Nanofibers of poly(lactic acid) (PLA) blended with polyaniline (PANi) were fabricated via electrospinning at much lower PLA concentrations (∼1wt%) in CHCl₃ than reported before using a more efficient technique of preparing the solutions. The polymer nanofibers had diameters in the range 10 nm–300 nm. Nanofibers prepared with a 3 wt% PLA/PANi solution were conducting and were used to fabricate a diode which was electrically characterized and exhibited a low turn-on voltage and a rectification ratio of 500. The device characteristics were analyzed using the standard thermionic emission model of a Schottky junction and yielded an ideality factor of 1.6 and a barrier height of 0.49 eV. Using a simple circuit, the diode was able to rectify a low frequency alternating current signal with an efficiency of 10%. The ability to engineer insulating PLA into nanofibers that are electro-active extends the range of applications of this biocompatible and biodegradable polyester to include electronic devices that have reduced toxicity.     

Design of sustainable V-based hydrogen separation membranes based on grain boundary segregation

Inter-diffusion between vanadium and palladium coating layers in vanadium-based hydrogen separation membranes is investigated by using a computational approach based on first-principles calculations and semi-empirical atomistic simulations, paying attention to the surface stability and the prevention of the degradation of hydrogen permeability. It is found that the governing mechanism of the inter-diffusion is the grain boundary diffusion, and therefore a diffusion barrier based on the grain boundary segregation of impurities can be an efficient way to inhibit the inter-diffusion that causes the degradation. An interesting aspect in previous experimental works that showed a good resistance to the inter-diffusion by an addition of a trace amount of yttrium is discussed from the view point of the grain boundary segregation. An experiment that proves the validity of the present alloy design scheme (inhibition of inter-diffusion using grain boundary segregation) is carried out, and a process to maximize the sustainability of the membrane is also proposed.     

The effect of LED irradiation on the quality of cabbage stored at a low temperature

The effects of light emitting diode (LED) irradiation on maintaining freshness and nutrition in cabbage during low temperature storage were investigated. Cabbage, ‘Dongdori’ was stored at 4–5°C for 18 days under white, green, blue, and red LED light. On day 15 of storage, the total chlorophyll content of cabbage was highest for green, followed by white, red, blue, and a nonirradiated control group. The vitamin C content was highest for blue, followed by white, green, red, and the control. On day 18 of storage, the total polyphenolic content in cabbage was highest for blue followed by white, red, green, and the control. LED irradiation is effective for enriching the chlorophyll, vitamin C, and polyphenol contents of cabbage stored at a low temperature and results suggest that LED colors have different effects.     

Pichia kudriavzevii is the major yeast involved in film-formation,off-odor production,and texture-softening in over-ripened Kimchi

Yeasts were isolated from over-ripened kimchi and identified. Isolates were identified as Pichia kudriavzevii, Kazachstania servazii, Kazachstania exigua, Kazachstania bulderi, and Rhodotorula mucilaginosa. Among the isolates, P. kudriavzevii GY1 and K. bulderi HY2 were separately inoculated into kimchi and incubated at 10°C for 21 days. After incubation, HY2 kimchi showed less offodors, whereas GY1 kimchi showed strong off- and moldyodors in the sensory evaluation. P. kudriavzevii GY1 showed significantly higher polygalacturonase activity than K. bulderi HY2. Volatile compounds in kimchi samples were analyzed by HSPM-GC. Peak areas of obnoxiousodor compounds, including methanethiol, were 6.61, 9.46, and 20.87% for control kimchi, HY2 kimchi, and GY1 kimchi, respectively. Therefore, P. kudriavzevii was mainly responsible for kimchi spoilage, including off-odors and texture softening. Moreover, K. bulderi was associated with kimchi deterioration at cell counts up to 8.0–9.0 log CFU/mL, even though its effects were not as strong as those of P. kudriavzevii.     

Nanotube morphology changes for Ti-Zr alloys as Zr content increases

Nanotube morphology changes in Ti-Zr alloys as Zr content increases have been investigated. Ti-Zr (10, 20, 30 and 40 wt.%) alloys were prepared by arc melting and heat treated for 24 h at 1000 °C in an argon atmosphere. TiO₂ nanotubes were formed on the Ti-Zr alloys by anodization in H₃PO₄ containing 0.5 wt.% NaF. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Samples were embedded in epoxy resin, leaving an area of 10 mm² exposed to the electrolyte. Anodization was carried out using a scanning potentiostat, and all experiments were conducted at room temperature. Microstructures of the alloys were examined by optical microscopy (OM), field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The Ti-Zr alloy microstructures observed by OM and FE-SEM changed from a lamellar structure to a needle-like structure with increasing Zr content. The microstructures also changed from β phase to increasing amounts of α phase as the Zr content increased. The number of large nanotubes formed by anodization decreased, and the number of small nanotubes increased, as the Zr content increased. The mean inner diameter ranged from approximately 150 to 200 nm with a tube-wall thickness of about 20 nm. The interspace between the nanotubes was approximately 60, 70, 100 and 130 nm for Zr contents of 10, 20, 30 and 40 wt.%, respectively.     

Remarkable asymmetric induction from remote stereocenters in conjugate addition chemistry for the synthesis of alkyl-branched α, ω-diaminoazelates

Conjugate addition of aryl Grignard reagents to (2S, 5E, 8S)-di-tert-butyl 4-oxo-2,8-bis-[N-(PhF)amino]non-5-enedioate ( 6 , PhF = 9-(9-phenyl-fluorenyl)) in THF proceeded with complete chemoselectivity and >9:1 stereoselectivity to provide predominantly (2S,6S,8S)-6-aryl 4-oxo-2,8-diamino-azelates 7 . In the presence of magnesium dibromide, diastereoselectivity in the addition of PhMgBr to enone 6 was improved to 15:1 in favor of the 6S-isomer. Although lower chemoselectivity and stereoselectivity were obtained from the analogous reaction of 6 with isopropyl magnesium bromide in the absence of MgBr₂, both were improved significantly when the addition reaction was performed in the presence of MgBr₂. In contrast, the corresponding higher-order cyanocuprates reacted with low diastereoselectivity on 6 by a 1,4-addition pathway. In an attempt to identify the source of the high selectivity in the conjugate addition chemistry with 6 and Grignard reagents, the syntheses of enones 12 and 13 provided model systems in which one of the two amino carboxylate moieties of 6 was replaced by a branched alkyl substituent. Conjugate addition reactions on 12 and 13 demonstrated that chemoselectivity with Grignard reagents in the 1,4-addition reaction was contingent on the presence of an amino carboxylate moiety near the ketone of the enone system. Furthermore, because diastereoselectivity with Grignard reagents was significantly lower in additions to amino enones 12 and 13 relative to diamino enone 6 , the presence of both amino carboxylate moieties has been highlighted as an important factor for remarkable asymmetric induction in the conjugate addition of Grignard reagents.     

The effects of regeneration-phase CO and/or H2 amount on the performance of a NOX storage/reduction catalyst

The effects of regeneration-phase CO and/or H₂, and their amounts as a function of temperature on the trapping and reduction of NO_X over a model and a commercial NO_X storage/reduction catalyst have been evaluated. Overall, for both catalysts, their NO_X removal performance improved with each incremental increase in H₂ concentration. For the commercial sample, using CO at 200 °C, beyond a small amount added, was found to decrease performance. The addition of H₂ to the CO-containing mixtures resulted in improved performance at 200 °C, but the presence of the CO still resulted in decreased performance in comparison to activity when just H₂ was used. With the model sample, the presence of CO resulted in very poor performance at 200 °C, even with H₂. The data suggest that CO poisons Pt sites, including Pt-catalyzed nitrate decomposition. At 300 °C, H₂, CO, and mixtures of the two were comparable for trapping and reduction of NO_X, although with the model sample H₂ did prove consistently better. With the commercial sample, H₂ and CO were again comparable at 500 °C, but mixtures of the two led to slightly improved performance, while yet again H₂ and H₂-containing mixtures proved better than CO when testing the model sample. NH₃ formation was observed under most test conditions used. At 200 °C, NH₃ formation increased with each increase in H₂, while at 500 °C, the amount of NH₃ formed when using the mixtures was higher than that when using either H₂ or CO. This coincides with the improved performance observed with the mixtures when testing the commercial.     

Enzymatic synthesis of low-calorie structured lipids in a solvent-free system

For the synthesis of low-calorie structured lipids (LCSL), transesterification between triacetin and stearic acid using immobilized lipase in a solvent-free system was investigated. Stearic acid, a long-chain saturated fatty acid, was incorporated mainly into the sn-1 and/or sn-3 positions of triacetin by lipase-catalyzed reaction. Three types of reactor systems (open, closed, and vacuum) were studied for the production of LCSL. The effects of various reaction variables such as water activity of substrates and lipase, molar ratio of substrates, stirring speed and reaction temperature were investigated. In the vacuum reactor system, a certain amount of water was added periodically to maintain the optimal water content of the reaction system. When a suitable amount of water (0.65 wt% of substrates) was added at every 1 h into the vacuum reactor system, more than 88% LCSL was obtained within 4 h using Chirazyme^® L-2.     

Factorial invariance of the Dyadic Adjustment Scale across gender.

The Dyadic Adjustment Scale (DAS; G. B. Spanier, 1976) is the most widely used inventory of relationship satisfaction in the social sciences, yet the question of whether it is measuring the same concept in men and women has never been addressed. In the current study, the authors examined the factor structure of the DAS in a sample of 900 currently married couples who participated in the Minnesota Twin Family Study. Confirmatory factor analysis was applied to a second-order factor solution with Spanier’s four factors (Dyadic Consensus, Dyadic Satisfaction, Dyadic Cohesion, Affectional Expression) loading on one higher order factor (Relationship Adjustment), to test for measurement invariance across gender. The second-order solution was relatively invariant across gender, even when taking into account the nonindependent nature of the data. This suggests that the best conceptualization of the DAS is one of a gender-invariant measure of marital adjustment with four distinct subfactors and that differences between men and women on any of these constructs can be interpreted by both clinicians and researchers as true mean differences rather than measurement bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)