驻波型热声驱动的脉管制冷机研究进展

系统地回顾了浙江大学在驻波型热声驱动器及其驱动的脉管制冷方面近10年来的研究进展,在简要描述相关实验系统结构的基础上,着重介绍了对热声驱动器的结构与运行参数的优化,以及在取得最优制冷性能方面的努力.报告了在自行研制的热声驱动脉管制冷机上取得88.6 K的最低制冷温度.     

Potential DNA–protein cross-link products formed by sugar degradation products: identification of N 6-[2-(N 2-2′-deoxyguanosyl)propionyl]lysine

Sugar degradation products are formed during heat treatment of food as well as endogenously in vivo. As reactive carbonyl compounds, they react readily with proteins or DNA to form protein- or DNA-bound advanced glycation end products (glycation reaction or Maillard reaction). In this study, we investigated the formation of potential DNA–protein cross-link products from sugar degradation products. 2-Deoxyguanosine, l-lysine and different carbohydrates were incubated at 37 °C. The sugar degradation products dihydroxyacetone and d,l-glyceraldehyde lead to the formation of two new cross-link products. The new compounds were isolated by preparative high-performance liquid chromatography and identified by spectral data as the two diastereomers of N⁶-[2-(N²-2-deoxyguanosyl)propionyl]lysine. In this structure, the -amino group of lysine and the exocyclic amine group of 2-deoxyguanosine are linked via a carboxyethyl group, derived from the carbohydrate component. The binding sites and the binding types were confirmed by synthesis of the analogous products from N²-(1-carboxyethyl)guanosine and N-acetyllysine methyl ester.Dedicated to Professor Th. Severin on the occasion of his 75^th birthday     

Chemistry and medicinal properties of the Bakul (Mimusops elengi Linn): A review

India is one of the world's biodiversity hotspots and reports confirm that a great variety of fruiting trees are indigenous to this region of the world. Mimusops elengi Linn (family Sapotaceae) commonly known as Bakul is one such tree native to the Western Ghat region of the peninsular India. However, today this tree is also found growing in other parts of the tropical and subtropical regions of the world. The tree is of religious importance to the Hindus and finds mention in various mythological texts. The stem, barks, leaves and fruits are used in various Ayurvedic and folk medications to treat various ailments. In the prehistoric days the ripe fruits were an important source of diet but today no one knows of its dietary use as it is seldom used. Studies suggest the tree contains medicinally-important chemicals, particularly the triterpenes and alkaloids. Preclinical studies in the past five years have shown that the extracts prepared from Bakul possess antibacterial, antifungal, anticariogenic, free radical scavenging, antihyperglycemic, antineoplastic, gastroprotective, antinociceptive and diuretic effects, thus lending pharmacological support to the tree's ethnomedicinal uses in Ayurveda. In this review for the first time attempt is made at addressing the chemical constituents, medicinal uses and validated pharmacological observations of Bakul.     

Phytochemistry, traditional uses and pharmacology of Eugenia jambolana Lam. (black plum): A review

Eugenia jambolana Lam. (syn. Syzigium cumini (L.) SKEELS; S. jambolana DC; Family: Myrtaceae), commonly known as black plum or Jamun is a plant native to India. Annually the trees produce oblong or ellipsoid fruits (berries). They are green when raw and purplish black when fully ripe. The ripe fruits are sweetish sour to taste and are used to prepare health drinks, squashes, juices, jellies and wine. Studies have shown that the berries contain carbohydrates, minerals and the pharmacologically active phytochemicals like flavonoids, terpenes, and anthocyanins. Jamun is a plant with known ethnomedicinal uses. Before the discovery of insulin, Jamun was useful in the treatment of diabetes and is an integral part in the various alternative systems of medicine. Scientific studies have shown that the various extracts of Jamun possess a range of pharmacological properties such as antibacterial, antifungal, antiviral, anti-genotoxic, anti-inflammatory, anti-ulcerogenic, cardioprotective, anti-allergic, anticancer, chemopreventive, radioprotective, free radical scavenging, antioxidant, hepatoprotective, anti-diarrheal, hypoglycemic and antidiabetic effects. The present paper reviews these aspects and also addresses the lacunas in the existing knowledge.     

Inhibitory effects of flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu) on antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells

We found that two distinct flavonoid glycosides isolated from the peel of Japanese persimmon (Diospyros kaki Fuyu), isoquercitrin (Isq) and hyperin (Hyp), are capable of inhibiting antigen-stimulated degranulation in rat basophilic leukaemia RBL-2H3 cells. In order to elucidate the underlying mechanisms, we examined effects of Isq and Hyp on cellular responses induced by antigen stimulation. Treatment with both Isq and Hyp markedly inhibited antigen-stimulated elevation of intracellular free Ca²⁺ concentration and reactive oxygen species (ROS). Isq and Hyp did not affect NADPH oxidase (NOX) activity, but they possessed DPPH radical-scavenging activity similar to that of epigallocatechin gallate, a potent anti-oxidant, Finally, Isq and Hyp showed little or no effects on Ag-stimulated Syk activation or phosphorylation of signalling molecules. These results indicate that inhibition of antigen-stimulated degranulation by Isq and Hyp is mainly due to suppression of intracellular Ca²⁺ elevation, which is caused by direct scavenging of ROS that are generated by NOX. Our findings suggest that Isq and Hyp, isolated from the peel of persimmon, would be beneficial for alleviating symptoms of type I allergy.     

With great expectations, can two "wrongs" prime a "right"?

The proportion of related prime-target pairs (relatedness proportion, RP) and prime-target stimulus onset asynchrony (SOA) was varied to determine the involvement of strategic priming mechanisms in the reduction in semantic priming that occurs when a target follows an unmasked prime that itself receives immediate repetition priming from a masked prime. At 300-ms and 1,200-ms SOAs, (a) strategic semantic priming was operating, in that priming from a nonrepeated prime increased as RP increased from .25 to .75, and (b) for both RPs, prime repetition reduced semantic priming. At a 167-ms SOA, (a) priming from a nonrepeated prime was unaffected by RP, suggesting that strategic priming was not operating, and (b) for both RPs, prime repetition did not reduce semantic priming. Because prime repetition did not reduce priming at the 167-ms SOA (when only spreading activation should have been mediating semantic priming), the reduction in semantic priming produced by prime repetition is not evidence against spreading activation automaticity. Possible mechanisms through which prime repetition reduces semantic priming are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

用于光码分多址系统中的跳频地址码研究

研究了光正交码,EQC码和素数码与频率相结合构成的单跳频及多跳频二维地址码,并对它们的容量与采用波分复用系统时的容量进行了比较,得到了比采用跳频地址码容量更大的结论。     

Performance of ATM traffic in optical CDMA

An ATM transit switch is proposed based on direct sequence optical code division multiple access technique. No buffering is necessary to facilitate the switching. Code conversion is used instead to emulate the switching function. The switch not only provides asynchronous access to the users but also has a limited capability of dynamic bandwidth allocation. It is free from timing jitters and switching delay is significantly reduced. A look‐up table is employed in the switching and updated through network management functions. The switch provides a new approach to asynchronous cross‐connection in the ATM core network. The performance of the new switch is evaluated by a set of prime codes and modified prime codes. Copyright © 2001 John Wiley & Sons, Ltd.     

再谈数的整除性特征定理

针对整数论中数的整除特征进行了研究,从理论上解决了任意整数的整除特征问题。     

High-temperature fuel cell membranes based on mechanically stable para-ordered polybenzimidazole prepared by direct casting

Poly[2,2′-(p-phenylene)-5,5′-bibenzimidazole] (pPBI) is synthesized by mixing 3,3′-diaminobenzidine tetrahydrochloride and terephthalic acid in polyphosphoric acid (PPA) at 240 °C for 12 h. pPBI can be cast in membrane form directly from a polymerization solution (direct casting) or from a methanesulfonic acid solution (MSA casting). Membranes obtained by direct casting are almost amorphous and have much higher acid doping levels and larger water uptake values than those prepared by MSA casting. As a result, the pPBI membrane from direct casting has a high proton conductivity of 0.15 S cm⁻¹ (at 180 °C and 1% relative humidity) at an acid doping level of 8.78 mol H₃PO₄ per mole of polymer repeat unit. Moreover, this membrane has good mechanical stability (tensile strength of 57 MPa at 22 °C and 24% relative humidity) even at this high doping level.