DTA

DTA
  • 文章类型: Journal Article
    结论:雌性配子体的遗传消融为拟南芥胚珠发育过程中区域间通讯的存在以及雌性配子体在珠叶尖端变性中的重要性提供了直接证据。被子植物胚珠由三个区域组成:雌配子体,核,和积分,所有这些都同步协调发展。以前,提出了促进胚珠合作发育的区域间交流;然而,这些交流的证据主要依赖于突变表型的分析.提供直接证据,我们通过在雌配子体特异性DD13启动子下表达白喉毒素片段A(DTA)来特异性消融拟南芥雌配子体,并分析了其对核和被膜发育的影响。我们发现雌配子体对于被膜发育或胚珠体的取向和弯曲是不需要的,但对于珠骨尖端变性是必需的。此处提供的结果为从雌配子体到核的交流提供了直接证据,并表明拟南芥胚珠需要区域间交流才能合作开发。
    CONCLUSIONS: Genetic ablation of the female gametophyte provides direct evidence for the existence of interregional communication during Arabidopsis ovule development and the importance of the female gametophyte in nucellar-tip degeneration. The angiosperm ovule consists of three regions: the female gametophyte, the nucellus, and the integuments, all of which develop synchronously and coordinately. Previously, interregional communication enabling cooperative ovule development had been proposed; however, the evidence for these communications mostly relies on the analysis of mutant phenotypes. To provide direct evidence, we specifically ablated the Arabidopsis female gametophyte by expressing the diphtheria toxin fragment A (DTA) under the female gametophyte-specific DD13 promoter and analyzed its effects on the development of the nucellus and the integuments. We found that the female gametophyte is not required for integument development or for the orientation and curvature of the ovule body, but is necessary for nucellar-tip degeneration. The results presented here provide direct evidence for communication from the female gametophyte to the nucellus and demonstrate that Arabidopsis ovules require interregional communication for cooperative development.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    心外膜细胞通过分泌多种生长因子并将谱系指定为其他心脏谱系来调节心脏生长。然而,心外膜细胞缺乏特异性标记基因,阻碍了对心脏发育中这种细胞类型的理解。通过对心脏单细胞mRNA测序数据集的分析,我们发现了一个新的心外膜基因,命名为角蛋白19(Krt19)。进一步分析Krt19和Wt1的表达模式,一种众所周知的心外膜基因,揭示了他们对主要心脏细胞类型的偏好。使用谱系追踪分析,我们在多个时间窗口分析了Krt19-CreER标记的细胞,发现其在胚胎和新生儿阶段都标记了心外膜细胞.此外,我们使用基于白喉毒素A链(DTA)的细胞消融系统研究了心外膜细胞的功能。我们发现Krt19-CreER标记的细胞对胎儿心脏发育至关重要。最后,我们研究了Krt19-CreER和Wt1-CreER标记的细胞在新生小鼠发育中的功能。我们观察到Krt19-CreER;Rosa-DTA小鼠在他莫昔芬治疗后表现出更小的尺寸,提示Krt19-CreER标记细胞在新生小鼠发育中的潜在重要性。此外,我们发现Wt1-CreER;Rosa-DTA小鼠在早期阶段死亡,可能是由于肾脏和脾脏的缺陷。总之,我们已将Krt19鉴定为新的心外膜细胞标记基因,并使用Krt19-CreER和Wt1-CreER介导的DTA消融系统进一步探索了心外膜细胞的功能.
    Epicardial cells regulate heart growth by secreting numerous growth factors and undergoing lineage specification into other cardiac lineages. However, the lack of specific marker genes for epicardial cells has hindered the understanding of this cell type in heart development. Through the analysis of a cardiac single cell mRNA sequencing dataset, we identified a novel epicardial gene named Keratin 19 (Krt19). Further analysis of the expression patterns of Krt19 and Wt1, a well-known epicardial gene, revealed their preferences in major cardiac cell types. Using lineage-tracing analysis, we analyzed Krt19-CreER labeled cells at multiple time windows and found that it labels epicardial cells at both embryonic and neonatal stages. Furthermore, we studied the function of epicardial cells using a diphtheria toxin A chain (DTA)-based cell ablation system. We discovered that Krt19-CreER labeled cells are essential for fetal heart development. Finally, we investigated the function of Krt19-CreER and Wt1-CreER labeled cells in neonatal mouse development. We observed that the Krt19-CreER; Rosa-DTA mice displayed a smaller size after tamoxifen treatment, suggesting the potential importance of Krt19-CreER labeled cells in neonatal mouse development. Additionally, we found that Wt1-CreER; Rosa-DTA mice died at early stages, likely due to defects in the kidney and spleen. In summary, we have identified Krt19 as a new epicardial cell marker gene and further explored the function of epicardial cells using the Krt19-CreER and Wt1-CreER-mediated DTA ablation system.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    秋季气温的动态波动,特别是明显的昼夜变化和随后的急剧下降是葡萄栽培中的关键和关键作用,当它们严重影响葡萄藤适应寒冷的过程时,从而直接影响他们在寒冷气候地区的生存和生产力。在这项全面的研究中,我们调查了四个葡萄品种的抗寒性:\'Itasca\',\'Frontenac\',\'LaCrescent\',和'Marquette',关注这些品种和它们的个体芽(第1,2nd,3rd,第四,5th,6th,Seven,8th,和9th)响应秋季典型的波动天气和低温[-1.1°C(30°F)-9.4°C(15°F)和-17.8°C(0°F)]。我们的结果揭示了抗寒性的惊人变化,这不仅在不同品种之间而且在同一藤本植物的单个芽中都表现出来,强调芽位置对藤蔓抗寒性的关键影响。\'Frontenac\'在10%的临界温度下显示出更高的抗寒性,与\'Itasca\'和\'LaCrescent\'相比,50%的休眠芽受到寒冷(LT10和LT50)的致命影响,与\'Marquette\'表现出中间值。然而,在“Itasca”和“Marquette”等品种中,当面对较冷的温度时,某些芽表现出明显的抵抗力,而其他人则表现出更高的敏感度,从而揭示了芽的位置和藤本植物承受寒冷胁迫的能力之间的细微差别。我们的研究揭示了与传统葡萄栽培理解的显着差异;顶芽表现出比基础芽更高的抗寒性,并为葡萄生理学研究开辟了新的途径。我们的结果还表明了一个重要的趋势,即所有研究品种的老葡萄藤都表现出增强的抗寒性,在临界LT50和临界温度下尤其明显,在临界温度下,90%的休眠芽受到寒冷(LT90)阈值的致命影响,与年轻的葡萄藤相比。此外,我们的发现揭示了秋季的昼夜温度变化和随后的温度下降对藤本植物抗寒性的影响,因此强调了环境温度动态和休眠芽硬度之间复杂的相互作用。总之,我们的研究表明,在北达科他州的葡萄藤中观察到的冷害不是秋季极端温度波动的结果。通过差热分析(DTA)和光学微分成核和膨胀分析(ODNEAL)方法测试葡萄藤达到各种阈值温度后,可以证实这一点。特别是在严重的冬前寒冷条件开始之前。这些全面的发现强调了藤蔓对气候条件和葡萄栽培管理的反应的复杂性,指出需要在葡萄园管理和品种选择方面采取特定策略,以在面对各种环境挑战时优化芽的硬度和生产力,尤其是在寒冷的气候葡萄栽培。
    The dynamic fluctuations in autumn temperatures, particularly the marked diurnal variations and the subsequent precipitous drops are key and a pivotal role in viticulture, as they critically influence the acclimation process of grapevines to cold, thereby directly impacting their survival and productivity in cold-climate regions. In this comprehensive study, we investigated the cold hardiness of four grapevine cultivars: \'Itasca\', \'Frontenac\', \'La Crescent\', and \'Marquette\', focusing on how these cultivars and their individual buds (1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, and 9th) respond to fluctuating weather and low temperatures typical of autumn [-1.1°C (30°F) -9.4°C (15°F) and -17.8°C (0°F)]. Our results illuminated the striking variability in cold hardiness that was manifest not only among the different cultivars but also within individual buds on the same vine, underscoring the critical influence of bud position on a vine for cold hardiness. \'Frontenac\' showed greater cold hardiness at critical temperatures at which 10%, and 50% of the dormant buds were lethally affected by cold (LT10 and LT50) compared to \'Itasca\' and \'La Crescent\', with \'Marquette\' exhibiting intermediate values. However, in cultivars such as \'Itasca\' and \'Marquette\', certain buds demonstrated a pronounced hardiness when faced with colder temperatures, while others exhibited a heightened sensitivity, thereby revealing a nuanced interplay between bud position and a vine\'s ability to withstand cold stress. Our study revealed a notable divergence from traditional viticulture understanding; apical buds demonstrated greater cold hardiness than basal buds and opened new paths for research into grapevine physiology. Our results also indicated a significant trend wherein older vines across all studied cultivars displayed enhanced cold hardiness, particularly pronounced at the critical LT50 and the critical temperature at which 90% of the dormant buds were lethally affected by cold (LT90) thresholds, in comparison to younger vines. Moreover, our findings shed light on the impact of autumn\'s diurnal temperature variations and the subsequent drop in temperatures on vine cold hardiness, thus highlighted the complex interplay between environmental temperature dynamics and dormant bud hardiness. In conclusion, our study showed that the cold damage observed in grapevines in North Dakota was not a result of extreme temperature fluctuations in the fall. This was confirmed by testing the vines after they had reached various threshold temperatures through differential thermal analysis (DTA) and optical differential nucleation and expansion analysis (ODNEAL) methodologies, particularly before the onset of severe pre-winter cold conditions. These comprehensive findings highlighted the complexity of the vine\'s response to climatic conditions and viticultural management, pointing to the need for specific strategies in vineyard management and cultivar selection to optimize bud hardiness and productivity in the face of various environmental challenges, especially in cold climate viticulture.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    背景:硫化铅纳米颗粒是使用印度阿育吠陀配方中描述的程序由氧化铅制成的,这涉及使用高达60普塔的热量,正式称为ShastiputaNagaBhasma。
    目的:研究表明,由于溶解度较低,纳米颗粒的硫化作用显着降低了其毒性。
    方法:本工作使用硫化砷介质和传统的puta进行处理,并进行了表征。不同的分析技术,如X射线衍射(XRD),扫描电子显微镜(SEM),能量色散X射线(EDX)光谱,傅里叶变换红外光谱(FTIR),使用热重分析(TGA)。研究表明,由于溶解度较低,纳米颗粒的硫化作用显着降低了其毒性。
    方法:本工作使用硫化砷介质和传统的puta进行Nagabhasma处理,并进行了表征。不同的分析技术,如X射线衍射(XRD),扫描电子显微镜(SEM),能量色散X射线(EDX)光谱,傅里叶变换红外光谱(FTIR),使用热重分析(TGA)。
    结果:粉末X射线衍射,扫描电子显微镜,傅里叶变换红外光谱,热重分析,差热分析和差热分析均表明,所制备的纳米颗粒为硫化铅纳米颗粒,平均粒径为84.60,平均粒径为69.06nm。
    结论:四舍五入,杆,椭圆形,立方,在SEM图像中可以看到所产生的硫化铅纳米颗粒的圆形形貌。样品中的拉伸和弯曲官能团是烷烃,烯烃,芳烃,芳烃,羧酸,烷基羧酸,烷基α,β-不饱和,醛类,酮,羧酸,脂肪胺,伯胺,仲胺,烷基卤化物,通过FTIR光谱研究烷基卤化物。
    BACKGROUND: Lead sulfide nanoparticles were manufactured from lead oxide using a procedure described in the Ayurveda formulary of India, which involved using a quantum of the heat of up to 60 puta, which is officially known as the Shasti puta Naga Bhasma.
    OBJECTIVE: The study shows sulfurization of nanoparticles decreased their toxicity due to the lower solubility.
    METHODS: The present work used the arsenic sulfide media and traditional puta for processing and the characterization of the same has been conducted. Different analytical techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-Ray (EDX) spectroscopy, Fourier transform infrared spectroscopy (FTIR), and thermo-gravimetry analysis (TGA) were used.
    RESULTS: Powder x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, Thermogravimetric analysis, and differential thermal analysis all showed that the produced nanoparticles are lead sulfide nanoparticles with a particle size of an average of 84.60 and the crystalline average size of 69.06 nm.
    CONCLUSIONS: The rounded, rod, oval, cubic, and circular morphology of the produced lead sulfide nanoparticles can be seen in the SEM image. The stretching and bending functional groups in the sample were alkanes, alkenes, aromatic hydrocarbons, carboxylic acids, alkyl carboxylic acids, alkyl alpha, beta-unsaturated, aldehydes, ketones, carboxylic acid, aliphatic amines, primary amines, secondary amines, alkyl halides, are studied through the FTIR spectrum.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    背景:直接血管造影术(DTA)是急性缺血性卒中(AIS)的血管内治疗(EVT)的一种新型护理途径,已被证明可缩短符合EVT的患者的治疗时间并改善临床结局。采用DTA途径的制度成本和影响成本的诸多因素尚未研究。在这项研究中,对于前循环出现AIS和疑似LVO的患者,我们评估了与传统CT途径相比,DTA途径相关的成本和主要成本驱动因素.
    方法:使用时间驱动的基于活动的成本核算(TDABC)模型从医疗机构的角度比较DTA和常规途径的成本。过程映射用于概述所有活动和资源(人员,设备,材料)两种途径中的每个步骤都需要。成本模型是使用我们的机构患者数据库和纽约州的人员成本平均工资开发的。总计,增量成本和比例成本是根据影响路径的机构和患者因素计算的.
    结果:与所有AIS患者的常规方法相比,DTA途径的总费用增加了$82,583.61(9%)。对于不符合EVT的患者,与CT途径相比,DTA途径的总费用增加了82,964.37美元(76%).对于符合EVT条件的患者,CT通路的总费用和单例患者费用分别增加380.76美元(0.04%)和5.60美元(0.04%).
    结论:由于DTA途径为不符合EVT的患者增加了82,964.37美元,需要适当的患者选择标准,以避免将不符合EVT的患者转移至血管造影组.
    BACKGROUND: Direct-to-angiography (DTA) is a novel care pathway for endovascular treatment (EVT) of acute ischemic stroke (AIS) that has been shown to reduce time-to-treatment and improve clinical outcomes for EVT-eligible patients. The institutional costs of adopting the DTA pathway and the many factors affecting costs have not been studied. In this study, we assess the costs and main cost drivers associated with the DTA pathway compared to the conventional CT pathway for patients presenting with AIS and suspected LVO in the anterior circulation.
    METHODS: Time driven activity based costing (TDABC) model was used to compare costs of DTA and conventional pathways from the healthcare institution perspective. Process mapping was used to outline all activities and resources (personnel, equipment, materials) needed for each step in both pathways. The cost model was developed using our institutional patient database and average New York state wages for personnel costs. Total, incremental and proportional costs were calculated based on institutional and patient factors affecting the pathways.
    RESULTS: DTA pathway accrued additional $82,583.61 (9%) in total costs compared to the conventional approach for all AIS patients. For EVT-ineligible patients, the DTA pathway incurred additional $82,964.37 (76%) in total costs compared to the CT pathway. For EVT eligible patients, the total and per-patient costs were greater in the CT pathway by $380.76 (0.04%) and $5.60 (0.04%) respectively.
    CONCLUSIONS: As the DTA pathway incurred additional $82,964.37 for EVT-ineligible patients, appropriate patient selection criteria are needed to avoid transferring EVT-ineligible patients to the angiography suite.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    Gremlin1(Grem1)是一种分泌蛋白,可拮抗骨形态发生蛋白(BMP)。据报道,异常的Grem1表达会导致产后小鼠的行为缺陷,大脑中GREM1的空间和细胞分布以及Grem1分泌细胞对脑功能和行为的影响尚不清楚。为了解决这个问题,我们设计了一个包含3×Flag-TeV-HA-T2A-td番茄序列的基因盒,从而创造了一个新的Grem1Tag小鼠模型,表达表位标签(3×Flag-TeV-HA-T2A),然后在内源Grem1启动子的控制下表达荧光报告分子(tdTomato)。这种设计有助于使用tdTomato和Flag(或HA)标记物精确跟踪GREM1在大脑中的细胞起源和分布。分别。我们确认Grem1Tag鼠标表现出正常的运动,认知,和产后60天的社会行为(P60),与C57BL/6J对照相比。通过免疫荧光染色,我们全面绘制了中枢神经系统中Grem1分泌细胞的分布图。在大脑皮层(Cx)中观察到普遍的Grem1表达,髓质,pons,还有小脑,Cx地区的最高水平。值得注意的是,在Cx内,GREM1主要由兴奋性神经元分泌,特别是那些表达钙/钙调蛋白依赖性蛋白激酶IIα(Camk2a),而抑制性神经元(小白蛋白阳性,PV+)和神经胶质细胞(少突胶质细胞,星形胶质细胞,和小胶质细胞)显示很少或没有Grem1表达。为了描述Grem1分泌细胞的功能意义,使用白喉毒素A(DTA)系统选择性消融P42导致小鼠焦虑样行为增加和记忆受损.总之,我们利用Grem1Tag小鼠模型的研究揭示了GREM1在小鼠大脑中的空间和细胞定位,揭示Grem1分泌细胞参与调节脑功能和行为的作用。我们的Grem1Tag鼠标是进一步探索Grem1在大脑发育和疾病中的精确作用的宝贵工具。
    GREMLIN1 (GREM1) is a secreted protein that antagonizes bone morphogenetic proteins (BMPs). While abnormal GREM1 expression has been reported to cause behavioral defects in postpartum mice, the spatial and cellular distribution of GREM1 in the brain and the influence of the GREM1-secreting cells on brain function and behavior remain unclear. To address this, we designed a genetic cassette incorporating a 3×Flag-TeV-HA-T2A-tdTomato sequence, resulting in the creation of a novel Grem1Tag mouse model, expressing an epitope tag (3×Flag-TeV-HA-T2A) followed by a fluorescent reporter (tdTomato) under the control of the endogenous Grem1 promoter. This design facilitated precise tracking of the cell origin and distribution of GREM1 in the brain using tdTomato and Flag (or HA) markers, respectively. We confirmed that the Grem1Tag mouse exhibited normal motor, cognitive, and social behaviors at postnatal 60 days (P60), compared with C57BL/6J controls. Through immunofluorescence staining, we comprehensively mapped the distribution of GREM1-secreting cells across the central nervous system. Pervasive GREM1 expression was observed in the cerebral cortex (Cx), medulla, pons, and cerebellum, with the highest levels in the Cx region. Notably, within the Cx, GREM1 was predominantly secreted by excitatory neurons, particularly those expressing calcium/calmodulin-dependent protein kinase II alpha (Camk2a), while inhibitory neurons (parvalbumin-positive, PV+) and glial cells (oligodendrocytes, astrocytes, and microglia) showed little or no GREM1 expression. To delineate the functional significance of GREM1-secreting cells, a selective ablation at P42 using a diphtheria toxin A (DTA) system resulted in increased anxiety-like behavior and impaired memory in mice. Altogether, our study harnessing the Grem1Tag mouse model reveals the spatial and cellular localization of GREM1 in the mouse brain, shedding light on the involvement of GREM1-secreting cells in modulating brain function and behavior. Our Grem1Tag mouse serves as a valuable tool for further exploring the precise role of GREM1 in brain development and disease.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Meta-Analysis
    背景:使用基于症状的胃食管反流病(GERD)问卷(GerdQ)诊断GERD已引起人们的兴趣,因为它比其他可用的问卷更有效且易于使用。然而,关于使用GerdQ作为诊断测试,不同的指南给出了不一致的建议.这项荟萃分析总结了GerdQ诊断GERD的准确性。
    方法:截至2023年4月12日的研究发表,并在MEDLINE中索引,EMBASE,Scopus,WebofScience,搜索了Cochrane图书馆.纳入了在有症状提示GERD的成年患者中比较GerdQ与上内镜和/或pH测定法对GERD诊断的诊断测试准确性研究。使用QUADAS-2工具评估研究质量。使用双变量(Reitsma)分析进行荟萃分析,以总结总体敏感性,特异性,似然比(LRs),和诊断比值比(DOR)。可视化汇总接收器工作特征(SROC)曲线,并计算ROC下面积(AUC)。
    结果:共有13项研究,11,166名参与者被纳入荟萃分析。汇集的敏感性,特异性,正LR,负LR,GerdQ的DOR(临界值≥8)为66.9%(95%CI56.4%-73.1%),65.2%(95%CI56.4%-73.1%),1.93(95%CI1.55-2.42),0.51(95%CI0.38-0.66),和3.89(95%CI2.44-5.89),分别。来自SROC的总体AUC为0.705。亚组分析显示相似的合并敏感性,特异性,和DOR在亚洲和非亚洲研究之间。
    结论:GerdQ对GERD诊断具有中等敏感性和特异性。GerdQ仍然可以推荐作为GERD的诊断工具,特别是当PPI测试不可用或禁忌时。
    BACKGROUND: The use of a symptom-based gastroesophageal reflux disease (GERD) questionnaire (GerdQ) for GERD diagnosis has gained interest due to its greater efficacy and ease of use than other available questionnaires. However, different guidelines have given inconsistent recommendations regarding using GerdQ as a diagnostic test. This meta-analysis summarized the diagnostic accuracy of GerdQ for diagnosing GERD.
    METHODS: Studies published up to April 12, 2023, and indexed in MEDLINE, EMBASE, SCOPUS, Web of Science, and the Cochrane Library were searched. Diagnostic test accuracy studies comparing GerdQ with upper endoscopy and/or pH-metry for GERD diagnosis in adult patients with symptoms suggestive of GERD were included. The study quality was assessed using the QUADAS-2 tool. Meta-analysis using bivariate (Reitsma) analysis was done to summarize the overall sensitivity, specificity, likelihood ratios (LRs), and diagnostic odds ratio (DOR). The summary receiver operating characteristics (SROC) curve was visualized, and the area under the ROC (AUC) was calculated.
    RESULTS: A total of 13 studies with 11,166 participants were included in the meta-analysis. The pooled sensitivity, specificity, positive LR, negative LR, and DOR for GerdQ (cut-off value of ≥8) were 66.9% (95% CI 56.4%-73.1%), 65.2% (95% CI 56.4%-73.1%), 1.93 (95% CI 1.55-2.42), 0.51 (95% CI 0.38-0.66), and 3.89 (95% CI 2.44-5.89), respectively. The overall AUC from the SROC was 0.705. The subgroup analysis showed similar pooled sensitivity, specificity, and DOR between Asian and non-Asian studies.
    CONCLUSIONS: GerdQ had moderate sensitivity and specificity for GERD diagnosis. GerdQ can still be recommended as a diagnostic tool for GERD, especially when the PPI test is unavailable or contraindicated.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Editorial
    暂无摘要。
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    开发了用于差热分析(DTA)的超响应单晶硅MEMS热电堆。由独特的“微孔交互和密封(MIS)”技术促进,成对的悬浮热电堆以差分形式批量制造,每个热电堆(样品面积〜0.045mm2)内集成了高密度(54对)n型/p型单晶硅热电偶。制造的MEMS热电堆传感器具有99.5V/W的出色功率响应度和27.8mV/°C的温度响应度,比材料热分析报告的高出4倍以上。高响应度MEMSDTA芯片使我们能够在〜1-100°C/s的不同加热速率下精确测量铟熔点。我们还对CuSO4·5H2O的脱水过程进行了DTA测量,晶体显示出在变成无水硫酸铜盐之前失去结晶水的三个阶段。我们的高性能,具有成本效益的MEMS传感芯片为广泛的应用提供了快速和准确的DTA表征的前景。
    Ultra-responsive single-crystal silicon MEMS thermopiles for differential thermal analysis (DTA) are developed. Facilitated by a unique \"microholes interetch and sealing (MIS)\" technique, pairs of suspended thermopiles are batch fabricated in a differential form, with high-density (54 pairs) n-type/p-type single-crystal silicon thermocouples integrated within each thermopile (sample area ~0.045 mm2). The fabricated MEMS thermopile sensors exhibit outstanding power responsivity of 99.5 V/W and temperature responsivity of 27.8 mV/°C, which are more than 4 times higher than those reported for material thermal analysis. The high-responsivity MEMS DTA chips allow us to accurately measure the indium melting point at different heating rates of ~1-100 °C/s. We also perform DTA measurement of the dehydration process of CuSO4·5H2O and the crystals show three stages of losing water of crystallization before becoming anhydrous copper sulfate salt. Our high-performance, cost-effective MEMS sensing chips hold promise for rapid and accurate DTA characterization for a wide range of applications.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    钛锆钼(TZM)是一种高温高强度合金,具有适用于高温结构应用的良好性能。在高压下使用TZM,最近证明了氨热法的含气体高压釜系统。希望在系统中使用铟(In),尽管目前普遍缺乏有关In对TZM机械性能的腐蚀和影响的文献和理解。这项研究首次报道了TZM在高达1000°C的温度下暴露于金属In后的机械性能。TZM在In中的静态腐蚀测试在750°C和1000°C下进行14天。进行微结构分析,表明晶粒结构没有可见的改变。进行差热分析(DTA)以研究In和TZM的主要成分之间的化合物形成,产生没有可测量的反应,因此没有明显的化合物形成。跨TZM-In界面的X射线能量色散光谱(EDS)线扫描显示,没有可测量的In质量传输到TZM基质中。使用X射线衍射(XRD)证实了这些结果。鉴于TZM对In的明显惰性,在22°C至800°C的测试温度下测量暴露于In后的TZM的机械性能,并与未暴露的相比较,来自相同材料库存的参考TZM样品。拉伸性能,包括极限抗拉强度,屈服强度和总伸长率,发现在暴露和未暴露的TZM样品之间具有可比性。在-196°C至800°C的温度下进行的冲击断裂韧性测试(夏比)表明,TZM在暴露于In时不受影响。拉伸测试表明在室温下的延性行为(慢应变速率),而冲击测试(高应变速率)表明延性到脆性转变温度在100°C和400°C之间。鉴于这些结果,TZM似乎是在高温下暴露于In时用作受力材料的有希望的候选者。
    Titanium zirconium molybdenum (TZM) is a high strength at high temperature alloy with favorable properties for use in high temperature structural applications. Use of TZM in high pressure, gas-containing autoclave systems was recently demonstrated for the ammonothermal method. Use of indium (In) in the system is desired, though there is a general lack of literature and understanding on the corrosion and impact of In on the mechanical properties of TZM. This study reports for the first time the mechanical properties of TZM after exposure to metallic In at temperatures up to 1000 °C. Static corrosion testing of TZM in In were performed at 750 °C and 1000 °C for 14 days. A microstructure analysis was performed suggesting no visible alteration of the grain structure. Differential thermal analysis (DTA) was performed to investigate compound formation between In and the primary constituents of TZM yielding no measurable reactions and hence no noticeable compound formation. X-ray energy dispersive spectroscopy (EDS) line scans across the TZM-In interface revealed no measurable mass transport of In into the TZM matrix. These results were confirmed using X-ray diffraction (XRD). Given the apparent inertness of TZM to In, mechanical properties of TZM after exposure to In were measured at test temperatures ranging from 22 °C to 800 °C and compared to unexposed, reference TZM samples from the same material stock. Tensile properties, including ultimate tensile strength, yield strength and total elongation, were found to be comparable between In-exposed and unexposed TZM samples. Impact fracture toughness testing (Charpy) performed at temperatures ranging from -196 °C to 800 °C showed that TZM is unaffected upon exposure to In. Tensile testing indicated ductile behavior at room temperature (slow strain rate) whereas impact testing (high strain rate) suggested a ductile to brittle transition temperature between 100 °C and 400 °C. Given these results, TZM appears to be a promising candidate for use as a force bearing material when exposed to In at high temperature.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

公众号