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DNA methylation assay for colorectal carcinoma 被引量:6
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作者 Ji-Jun chen Ai-Qin Wang qing-qi chen 《Cancer Biology & Medicine》 SCIE CAS CSCD 2017年第1期42-49,共8页
Colorectal carcinoma(CRC) is a common cause of morbidity and mortality worldwide. Two pathogenic pathways are involved in the development of adenoma to CRC. The first pathway involves APC/β-catenin characterized by c... Colorectal carcinoma(CRC) is a common cause of morbidity and mortality worldwide. Two pathogenic pathways are involved in the development of adenoma to CRC. The first pathway involves APC/β-catenin characterized by chromosomal instability resulting in the accumulation of mutations. The second pathway is characterized by lesions in DNA mismatch repair genes.Aberrant DNA methylation in selected gene promoters has emerged as a new epigenetic pathway in CRC development. CRC screening is the most efficient strategy to reduce death. Specific DNA methylation events occur in multistep carcinogenesis.Epigenetic gene silencing is a causative factor of CRC development. DNA methylations have been extensively examined in stool from CRC and precursor lesions. Many methylated genes have been described in CRC and adenoma, although no definite DNA methylation biomarkers panel has been established. Multiple DNA methylation biomarkers, including secreted frizzled-related protein 2, secreted frizzled-related protein 1, tissue factor pathway inhibitor 2, vimentin, and methylguanine DNA methyltransferase, have been further investigated, and observations have revealed that DNA methylation biomarkers exhibit with high sensitivity and specificity. These markers may also be used to diagnose CRC and adenoma in early stages. Real time polymerase chain reaction(q PCR) is sensitive, scalable, specific, reliable, time saving, and cost effective. Stool exfoliated markers provide advantages, including sensitivity and specificity. A stool q PCR methylation test may also be an enhanced tool for CRC and adenoma screening. 展开更多
关键词 BIOMARKER colorectal carcinoma DNA methylation real time PCR STOOL
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表面增强拉曼光谱原位捕获Pt-NiO界面水煤气变换反应中的碳酸盐中间物种
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作者 覃思纳 魏笛野 +6 位作者 魏杰 林嘉盛 陈清奇 吴元菲 金怀洲 张华 李剑锋 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2022年第8期2010-2016,共7页
水煤气变换反应(WGSR)是制备高纯氢的重要反应之一,一直是人们的研究热点.以Pt为代表的贵金属催化剂,在低温条件下表现出优异的WGSR活性.其中,Pt可还原性氧化物界面往往被认为是水煤气变换反应最高效的活性位点.然而,由于缺乏直接的光... 水煤气变换反应(WGSR)是制备高纯氢的重要反应之一,一直是人们的研究热点.以Pt为代表的贵金属催化剂,在低温条件下表现出优异的WGSR活性.其中,Pt可还原性氧化物界面往往被认为是水煤气变换反应最高效的活性位点.然而,由于缺乏直接的光谱证据,该界面处的水煤气变换反应分子机理仍然存在争议.本文通过制备具有三元核壳结构的Au@Pt@NiO纳米结构,在具有高表面增强拉曼效应的Au纳米颗粒表面构建了丰富的Pt-NiO界面,成功实现了Pt-NiO界面处WGSR过程及其关键中间物种的原位表面增强拉曼光谱(SERS)研究.通过控制镍前驱体的量,结合透射电镜和元素面扫描表征,制备了一系列具有不同NiO壳层厚度的Au@Pt@NiO纳米结构.以CO作为探针分子,利用原位SERS表征,当镍前驱体添加量为0.05 mL时,可以同时得到Pt-C以及Ni-O的拉曼信号,说明此时NiO是以岛状形式沉积于Au@Pt表面,从而构筑出丰富的Pt-NiO界面.原位SERS测试结果表明,当将此Au@Pt@NiO纳米粒子置于WGSR气氛时,随着反应温度的升高,在1065 cm^(-1)处出现了碳酸根物种的拉曼信号.而当将Au@Pt@NiO纳米粒子置于单独Ar,CO和气态水的气氛条件下时,均未观察到与新物种相关的拉曼信号产生.进一步研究结果表明,碳酸根物种的拉曼信号强度随着反应温度的上升呈现先增加后减少的趋势,且在130 ℃便已出现(此时并未测到WGSR活性),并在200 ℃显示出最大值(WGSR的起燃温度).同时,在气氛切换实验结果表明,若体系中先通入CO/Ar,再切换成H_(2)O/Ar时,可在Au@Pt@NiO表面观察到碳酸盐物种的生成;反之,若先通入H_(2)O/Ar,再切换为CO/Ar时,则无碳酸盐物种.说明碳酸盐物种是通过吸附的CO与气态水反应生成的,并且在催化剂表面可以稳定吸附,需要在更高温度才可分解,故碳酸盐的分解可能是WGSR中一个较为缓慢的步骤.此外,当将Au@Pt和Au@NiO置于WGSR气氛条件下进行对照实验,并没有观察到碳酸盐物种生成.这表明Pt-NiO界面可促进碳酸盐中间物种的形成,从而导致该界面比纯Pt表面具有更高的水煤气变换反应活性.本文研究结果加深了对WGSR机理的认识,有望用于指导高效WGSR催化剂的设计. 展开更多
关键词 水煤气变换反应 表面增强拉曼光谱 核壳纳米结构 原位表征 碳酸盐中间物种
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