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91.
Alpha-Lipoic acid has recently been permitted for use in foodstuffs and is contained in tablets and capsules. Although alpha-lipoic acid is synthesized from adipic acid, the safety of polymers produced during the purification and drying processes has been an issue of concern. Hence, we examined the safety profiles of thermally denatured polymer (LAP-A) and ethanol-denatured polymer (LAP-B) produced in the manufacturing process of alpha-lipoic acid. Furthermore, we conducted structural analysis of these polymers by 1H-NMR and FAB-MS spectroscopy. In a consecutive ingestion test, male and female mice ingested diet containing 0.1 and 0.2% LAP-A and -B for 4 weeks. Blood uric acid, potassium and lactate dehydrogenase (LDH) tended to increase without dose-dependency. Relative liver weights were also increased. However, male dogs that were orally administered LAP-B (500 mg/kg) once did not show any abnormalities in blood parameters or general condition. These findings indicate that alpha-lipoic acid polymers are not acutely toxic; however, chronic ingestion of these polymers may affect liver and kidney functions.  相似文献   
92.
Summary Poly(phenylene oxide) (PPO) — aromatic polyester multiblock copolymers were synthesized by polycondensation of bisphenol-A / isophthalic acid or m- and p-hydroxybenzoic acids in the presence of PPO having a carboxylic acid at one end and a phenolic hydroxy group at the other using triphenylphosphine / hexachloroethane as coupling agent. TG analysis showed that the multiblock copolymer showed relatively high thermal stability. Received: 5 January 1998/Accepted: 4 February 1998  相似文献   
93.
Recently, a polymerization process of Anilinium‐Dodecyl Benzene Sulfonic Acid (DBSA) complex in an aqueous dispersion was developed in our laboratories. Simple mechanical mixing of the aqueous PANI–DBSA dispersion with a PVAc aqueous latex leads to highly conductive blends at low PANI–DBSA contents. The percolation threshold of the dried films is extremely low (∼0.5 wt %). The combined aqueous PVAc/PANI–DBSA dispersions exhibit a gradually decreasing electrical conductivity accompanied by a gradually increasing viscosity, with the storage time. However, an aged cast film from these blends maintains its electrical conductivity with time. These phenomena are associated with acidic hydrolytic reactions of the ester group, resulting in the formation of vinyl acetate–vinyl alcohol copolymer and evolution of acetic acid, and also the interaction of the DBSA surfactant with the PVAc, causing swelling and disintegration of PVAc particles. A chemical structural model describing these changes with storage time is suggested. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 760–766, 2001  相似文献   
94.
Prion diseases are a group of fatal neurodegenerative disorders caused by accumulation of proteinaceous infectious particles, or prions, which mainly consist of the abnormally folded, amyloidogenic prion protein, designated PrPSc. PrPSc is produced through conformational conversion of the cellular isoform of prion protein, PrPC, in the brain. To date, no effective therapies for prion diseases have been developed. In this study, we incidentally noticed that mouse neuroblastoma N2a cells persistently infected with 22L scrapie prions, termed N2aC24L1-3 cells, reduced PrPSc levels when cultured in advanced Dulbecco’s modified eagle medium (DMEM) but not in classic DMEM. PrPC levels remained unchanged in prion-uninfected parent N2aC24 cells cultured in advanced DMEM. These results suggest that advanced DMEM may contain an anti-prion compound(s). We then successfully identified ethanolamine in advanced DMEM has an anti-prion activity. Ethanolamine reduced PrPSc levels in N2aC24L1-3 cells, but not PrPC levels in N2aC24 cells. Also, oral administration of ethanolamine through drinking water delayed prion disease in mice intracerebrally inoculated with RML scrapie prions. These results suggest that ethanolamine could be a new anti-prion compound.  相似文献   
95.
Deep‐blue fluorescent compounds are particularly important in organic light‐emitting devices (OLEDs). A donor–accepotor (DA)‐type blue‐emitting compound, 1‐(10‐(4‐methoxyphenyl)anthracen‐9‐yl)‐4‐(10‐(4‐cyanophenyl)anthracen‐9‐yl)benzene ( BD3 ), is synthesized, and for comparison, a nonDA‐type compound, 1,4‐bis(10‐phenylanthracene‐9‐yl)benzene ( BD1 ) and a weak DA‐type compound, 1‐(10‐phenylanthracen‐9‐yl)‐4‐(10‐(4‐cyanophenyl)anthracen‐9‐yl)‐benzene ( BD2 ), are also synthesized. The twisted conformations of the two anthracene units in the compounds, confirmed by single crystal X‐ray analysis, effectively prevent π‐conjugation, and the compound shows deep‐blue photoluminescence (PL) with a high PL quantum efficiency, almost independent of the solvent polarity, resulting from the absence of an intramolecular charge transfer state. The DA‐type molecule BD3 in a non‐doped device exhibits a maximum external quantum efficiency (EQE) of 4.2% with a slight roll‐off, indicating good charge balance due to the DA‐type molecular design. In the doped device with 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl (CBP) host, the BD3 exhibits higher EQE than 10% with Commission International de L'Eclairge (CIE) coordinates of (0.15, 0.06) and a narrow full‐width at half‐maximum of 45 nm, which is close to the CIE of the high definition television standard blue.  相似文献   
96.
In the present study, a conductive polyaniline-dodecyl benzene sulfonic acid (PANI-DBSA) complex, prepared by a thermal doping process, and its blends with thermoplastic polymers, prepared by melt processing, were investigated. PANI-DBSA characterization included conductivity measurements, morphology, crystallography, and thermal behavior. The blends' investigation focused on the morphology and the interaction between the components and on the resulting electrical conductivity. The level of interaction between the PANI and the matrix polymer determines the blend morphology and, thus, its electrical conductivity. Similar solubility parameters of the two polymeric components are necessary for a high level of PANI dispersion within the matrix polymer and, thus, enable the formation of conducting paths at low PANI content. The morphology of these blends is described by a two-structure hierarchy: (a) a primary structure, composed of small dispersed polyaniline particles, and (b) a short-range fine fibrillar structure, interconnecting the dispersed particles. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 243–253, 1997  相似文献   
97.
The antioxidative effects of vegetable extracts were evaluated using linoleic acid emulsion and liposomal phospholipid suspension systems. First, the antioxidative activities of water, ethanol and 2% metaphosphoric acid extracts of the vegetables were investigated by measuring the rate of oxygen consumption in the peroxidation of linoleic acid initiated by a radical generator, 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH), with a Clark electrode in the absence of metal chelators. Ethanol extracts of moroheiya and perilla exhibited the highest antioxidative activities. Without metal chelators, 12 ethanol extracts and one water extract acted as prooxidants, and this phenomenon could be attributed to the prooxidant action of ascorbic acid in the presence of free transition metal ions. Next, peroxyl radical-scavenging activities of vegetable extracts were examined by adding a metal chelator, diethylenetriaminepentaacetic acid (DTPA), to the linoleic acid emulsion system. The results were compared with their antioxidative activities in phospholipid bilayers by measuring the inhibition of lipid peroxidation in large unilamellar vesicles composed of egg yolk phosphatidylcholine (PC). A good correlation was observed between the antioxidative activities obtained from these two systems. The antioxidative activities in the liposomal phospholipid suspension system correlated with total contents of ascorbic acid and polyphenols in vegetable extracts. © 1999 Society of Chemical Industry  相似文献   
98.
在电-气-热综合能源系统(Intergrated Power、Gas and Heat Energy Systems,IPGHES)中,利用电力、热力和天然气的互补特性可以提高综合能源中可再生能源的消纳能力.电力系统、热力系统和天然气系统通过热电联产、电转气等设备互相耦合,文中采用可分离热电燃气轮机模型并计及了电转气技...  相似文献   
99.
This paper analyzes the effect of fuzzy logic-controlled superconductive magnetic energy storage (SMES) on minimizing shaft torsional oscillations of synchronous generators in a multi-machine power system. The proposed fuzzy logic controller has been designed in a very simple way considering only one input variable and one output variable. The time derivative of the total kinetic energy deviation (TKED) of the synchronous generators is used as the global input to the fuzzy controller for SMES switching. The influence of time delay associated with the global input calculation of the fuzzy controller on minimizing shaft torsional oscillations is investigated. Global positioning system (GPS) is proposed for the practical implementation of the calculation of the global input to the fuzzy controller. Simulation results of a balanced fault at different points in a multi-machine power system show that the proposed SMES can minimize the shaft torsional oscillations of synchronous generators well. Moreover, the time delay has an influence on the performance of fuzzy controlled SMES to minimize shaft torsional oscillations. However, even though the performance of fuzzy controlled SMES is somewhat effected by the communication delay, it is clear from the simulation responses that the fuzzy logic-controlled SMES considering typical communication delays can minimize the shaft torsional oscillations of synchronous generators well.  相似文献   
100.
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