绿豆生物活性物质及功能的研究进展

综述了绿豆生物活性物质及功能的研究进展。绿豆的生物活性物质包括蛋白水解酶、胰蛋白酶抑制剂、苯丙氨酸解氨酶、超氧物歧化酶(SOD)、黄酮类化合物、植物凝集素和抗真菌蛋白等。它具有抗菌、抗肿瘤、抗氧化、提高免疫力、降血脂和解毒等生理功能。提取、纯化绿豆中新的生物活性物质,探索其在农业、功能食品和医学上的应用,是进一步研究的方向。     

A novel multifunctional phosphorous and nitrogenous reactive flame retardant toward epoxy resins by one-pot method

Epoxy resin (EP) has attracted considerable attention in packaging, electronic devices, aerospace, and coatings fields owing to its remarkable chemical and physical performance. However, the inherent flammable performance and unfavorable brittle nature seriously restricted its application in sophisticated industry. Herein, an efficient reactive 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DB-DAD) was prepared by a facile “one-pot” method. Due to their synergistic gas-phase and solid-phase flame-retardant effects, DB-DAD modified EP composites (EP/DB-DAD composite) easily achieved UL-94 V-0 ratings, and an EP/DB-DAD composite with a 0.32 wt% phosphorus content had an excellent (30.2%) limiting oxygen index. In addition, the amounts of heat and smoke decreased by 28.1% and 24.8%, respectively. Due to the introduction of long and flexible aliphatic chains, the EP/DB-DAD composites exhibited satisfactory mechanical properties, the flexural and tensile toughness of EP/6% DB-DAD were 82.5% and 62.2% higher than those of neat EP, respectively. Furthermore, EP/DB-DAD composite showed good transparency (>85%) and favorable UV shielding performance. The EP/DB-DAD composite with good comprehensive performance is extremely promising to accelerate EP application in high-tech industries.     

Microwave acid digestion and preconcentration neutron activation analysis of biological and diet samples for iodine

A simple preconcentration neutron activation analysis (PNAA) method has been developed for the determination of low levels of iodine in biological and nutritional materials. The method involves dissolution of the samples by microwave digestion in the presence of acids in closed Teflon bombs and preconcentration of total iodine, after reduction to iodide with hydrazine sulfate, by coprecipitation with bismuth sulfide. The effects of different factors such as acidity, time for complete precipitation, and concentrations of bismuth, sulfide, and diverse ions on the quantitative recovery of iodide have been studied. The absolute detection limit of the PNAA method is 5 ng of iodine. Precision of measurement, expressed in terms of relative standard deviation, is about 5% at 100 ppb and 10% at 20 ppb levels of iodine. The PNAA method has been applied to several biological reference materials and total diet samples.     

Reliability comparison of an n cascade system with the addition of an n strength system

In the present paper we are comparing the reliability of two models: (i) the cascade system and (ii) the system having n strengths on a single stress. In both the cases the system has n strengths and a single stress. In the first case n strengths are cascaded and for each attack the stress is decreased. Whereas in the second case n strengths act in combination on the stress component. From the results obtained we can observe that when the attenuation factor is less than 0.5 the cascade model is more reliable, otherwise the second one is more reliable. Hence we infer that, at each attack, if the stress decreases the cascade model is more reliable.     

Oxidative damage to the eye lens caused by cigarette smoke and fuel smoke condensates

The degree to which a reformed U.S. health care system relies on an adequate supply of primary care physicians will determine the urgency of change in the composition of the medical workforce. In many areas of the United States, the demand for primary care physicians, particularly in managed care settings, far exceeds the supply. In contrast, reports of reduced practice opportunities for medical and surgical subspecialists in the same settings are increasing. As opportunities for and incomes of primary care physicians are enhanced, some medical subspecialists may seek retraining in primary care. This article provides a context for understanding the development of physician retraining programs, examines precedents for retraining physicians, describes four possible pathways through which medical subspecialists might acquire primary care training, and emphasizes the importance of defining the scope of practice and necessary skills for providing primary care. Obstacles to retraining appear to be economic (Who will pay? Is the cost worth the benefit?) and jurisdictional (Who will define core competencies? Who will credential programs and trainees?). The current absence of demand for such retraining programs suggests either that marketplace-induced changes will not take place or that the notion of a primary care provider shortage and an oversupply of medical subspecialists is overstated. The inclusion of physician retraining programs in proposed health reform legislation suggests that policymakers are convinced that such programs offer one viable solution to the nation's medical workforce needs.     

Effect of germination on tannin,mineral, and trace element composition of groundnut varieties

Groundnut varieties were analyzed for their tannin, ionizable iron, soluble zinc, phytate phosphorus, total iron, total phosphorus, total zinc, copper, magnesium, and manganese contents in ungerminated seed and after 0, 24, 48, and 72 h of germination. Tannin content varied between 100 and 623 mg/100 g; ionizable iron ranged from 136–2178 μg/100 g; phytate phosphorus ranged from 415–655 mg/100 g; soluble zinc varied between 776 and 951 μg/100 g of kernels. Soaking groundnuts overnight in water resulted in a decrease in content of most of the minerals, trace elements, tannins, and soluble zinc. As the germination period increased from 0 to 24, 48, and 72 h, ionizable iron (50%) and soluble zinc (95%) increased substantially. Ionizable iron as percent of total iron increased from 10% in ungerminated kernels to 23% in 72-h germinated kernels. Soluble zinc as percent of total zinc also increased from 18% in ungerminated groundnuts to 31% in 72-h germinated ones. There was a negative correlation between tannin content and ionizable iron content of ungerminated and germinated kernels (r=−0.5203). Germination decreased the antinutritional factors, such as tannin, and increased the bioavailable forms of iron and zinc, namely ionizable iron and soluble zinc contents of groundnut kernels.     

Kinetics of the direct synthesis of molycarbide by reduction-carburization of molybdenite in the presence of lime

Kinetic studies were conducted on the carbon monoxide reduction of molybdenite in the presence of lime. Contrary to the expectation that the MoS₂ (s)+CaO (s)+CO (g) reaction will result in metal formation, molycarbide was found to form and no Mo was detected in the product. This is explained on the basis of thermochemical considerations, which indicate that the Mo₂C formation is more feasible by eight orders of magnitude. The effects of quantity of lime in the charge, CO flow rate, temperature (1123 to 1298 K), and time of reduction have been studied. Kinetic analysis reveals that the results on the MoS₂ (s) conversion to Mo₂C (s) fit into a modified parabolic rate law. Based on the thermochemical calculations and experimental findings, the probable reaction scheme has been identified. Molycarbide appears to form by a three-successive solid-gas reaction path consisting of (1) metal formation by the MoS₂ (s)+CO (g) reaction followed by (2) in-situ carburization of Mo metal by CO (g), and finally (3) the scavenging of the COS (g) by lime, resulting in CaS (s). The latter two reactions drive the overall reaction forward. Further, out of these three consecutive reactions, progress of the overall MoS₂+CaO+CO reaction seems to be governed by the intrinsic kinetics of the first one. Calcium molybdate, which forms as a transitory phase, plays a significant role by modifying the linear kinetics of the MoS₂ (s)+CO (g) to one of parabolic nature.     

Recent developments of collagen-based materials for medical applications and drug delivery systems

In this review, an attempt was made to summarize some of the recent developments in the application of collagen as a biomaterial and in drug delivery systems. The main applications covered include: collagen for burn/wound cover dressings; osteogenic and bone filling materials; antithrombogenic surfaces; and immobilization of therapeutic enzymes. Recently, collagen used as a carrier for drug delivery has attracted many researchers throughout the world. The use of collagen for various drug delivery systems has also been reviewed in this article. Collagen-based drug delivery systems include: injectable microspheres based on gelatin (degraded form of collagen); implantable collagen-synthetic polymer hydrogels; interpenetrating networks of collagen; and synthetic polymers collagen membranes for ophthalmic delivery. Recent efforts to use collagen-liposomal composites for controlled drug delivery, as well as collagen as controlling membranes for transdermal delivery, were also reviewed. In this review, the main emphasis was on the work done in our laboratory.     

Surface-bound heparin fails to reduce thrombin formation during clinical cardiopulmonary bypass

The hypothesis that heparin-coated perfusion circuits reduce thrombin formation and activity; fibrinolysis; and platelet, complement, and neutrophil activation was tested in 20 consecutive, randomized adults who had cardiopulmonary bypass. Twenty identical perfusion systems were used; in 10, all blood-contacting surfaces were coated with partially degraded heparin (Carmeda process; Medtronic Cardiopulmonary, Anaheim, Calif.). All patients received a 300 U/kg dose of heparin. Activated clotting times were maintained longer than 400 seconds. Cardiopulmonary bypass lasted 36 to 244 minutes. Blood samples for platelet count, platelet response to adenosine diphosphate, plasma beta-thromboglobulin, inactivated complement 3b, neutrophil elastase, fibrinopeptide A, prothrombin fragment F1.2, thrombin-antithrombin complex, tissue plasminogen activator, plasminogen activator inhibitor-1, plasmin alpha 2-antiplasmin complex, and D-dimer were obtained at these times: after heparin was given, 5 and 30 minutes after cardiopulmonary bypass was started, within 5 minutes after bypass was stopped, and 15 minutes after protamine was given. After cardiopulmonary bypass, tubing segments were analyzed for surface-adsorbed anti-thrombin, fibrinogen, factor XII, and von Willebrand factor by radioimmunoassay. Heparin-coated circuits significantly (p < 0.001) reduced platelet adhesion and maintained platelet sensitivity to adenosine diphosphate (p = 0.015), but did not reduce release of beta-thromboglobulin. There were no significant differences between groups at any time for fibrinopeptide A, prothrombin fragment F1.2, or thrombin-antithrombin complex or in the markers for fibrinolysis: D-dimer, tissue plasminogen activator, plasminogen activator inhibitor-1, and alpha 2-antiplasmin complex. In both groups, concentrations of prothrombin fragment F1.2 and thrombin-antithrombin complex increased progressively and significantly during cardiopulmonary bypass and after protamine was given. Concentrations of D-dimer, alpha 2-antiplasmin complex, and plasminogen activator inhibitor-1 also increased significantly during bypass in both groups. Fibrinopeptide A levels did not increase during bypass but in both groups increased significantly after protamine was given. No significant differences were observed between groups for levels of inactivated complement 3b or neutrophil elastase. Radioimmunoassay showed a significant increase in surface-adsorbed antithrombin on coated circuits but no significant differences between groups for other proteins. We conclude that heparin-coated circuits used with standard doses of systemic heparin reduce platelet adhesion and improve platelet function but do not produce a meaningful anticoagulant effect during clinical cardiopulmonary bypass. The data do not support the practice of reducing systemic heparin doses during cardiac operations with heparin-coated extracorporeal perfusion circuitry.