Which is the best choice for gastroesophageal disorders:Melatonin or proton pump inhibitors?

Melatonin is used in many countries to improve sleep disorders.Melatonin is a hormone produced by the pineal gland and enterochromaff in cells which control sleep and gastrointestinal motility.Low levels of melatonin lead to gastroesophageal reflux disease(GERD).Most of patients with GERD have a sleep disorder.So,low melatonin levels is the main cause of insomnia.Beyond this,it has an inhibitory action on gastric acid secretion and seems to control the lower esophageal sphincter.Proton pump inhibitors(PPIs) are a group of drugs whose main action is a pronounced and long-lasting reduction of gastric acid production.They are the most potent inhibitors of acid secretion available today.Omeprazole(one of the PPIs) and melatonin have similarities in their chemical structures.Therefore,we could consider omeprazole as a rough copy of melatonin.In this paper,we compare the advantages and disadvantages of the clinical use of melatonin and PPIs.

采用Cr_3C_2-NiCr和WC-CoCr粉末的HVOF处理(英文)

磨损是工业上导致零件和装备失效的三个主要问题中的一个。人们在不断探索改善零件性能的潜力,提出新的技术,力图提高零件的使用寿命,降低运作成本。由此看来,电镀及涂覆技术是很重要的。人们已经采用传统的镀硬铬来改善耐磨性(或)耐蚀性,然而电镀过程中会产生有害的致癌物质六价铬,致使其应用受到了越来越大的限制。因此,必须鉴别和研发无毒的、非致癌的和对环境友好的涂覆材料和工艺。其中用本文所述的HVOF工艺涂覆的"陶瓷合金"(Cr3C2-NiCr-WC-CoCr)前景最被看好。用光学和电子显微分析法、X射线衍射法、密度和显微磨料磨损试验标征了用这种工艺获得的涂层的特性。从总体上看,WC-CoCr涂层的性能最好,由此可以认为,它是一种前景广阔、可以替代电镀硬铬的涂覆技术。