Hot Cracking Susceptibility of 800H and 825 Nickel-Base Superalloys during Welding via Spot Varestraint Test

Hot cracking susceptibility of fillers 52 and 82 in 800H and 825 nickel-base superalloys was discussed using the Spot Varestraint test. The fillers of 52 and 82 were added into nickel-base superalloys via a gas tungsten arc welding (GTAW).Experimental results showed that the hot cracking sensitivity of the nickel-base superalloys with filler at high temperature was lower than that without filler. The hot cracking sensitivity had a slight effect when the filler 82 was added. The total length of crack was increased, the liquid-solid (L-S) two-phase range is higher so that the hot cracking susceptibility will be raised. The morphologies of cracks included the intergranular crack in the molten pool, molten pool of solidification cracking, heat-affected zone of intergranular cracks, and transgranular crack in the heat-affected zone

The prevalence of ocular diseases in primary and junior high school students on Orchid Island

AbstractObjectiveTo assess the prevalence of refractive error and ocular diseases in primary and junior high school students on Orchid Island.Materials and MethodsThis is a cross-sectional study of all students in the primary and junior high schools on Orchid Island conducted within 1 week in 2008. Each student received a visual acuity examination without correction with the Landolt-C chart. An experienced ophthalmologist performed associated assessments through retinoscopy, slit lamp, and fundoscopy.ResultsOf the 403 student residents, 260 were primary school students (139 boys and 121 girls) and 143 were junior high school students (74 boys and 69 girls). Visual acuity in two eyes was < 0.1, in 14 eyes was between 0.1 and 0.3, in 34 eyes was between 0.4 and 0.7, in 225 eyes was between 0.8 and 1.0, and in 531 eyes was between 1.2 and 2.0. Myopia was found in 21 students (21/403, 5.21%; 9 primary school students and 12 junior high school students). Four students (4/403, 0.99%) had amblyopia, of whom two had anisometropia (unilateral high hyperopia), one had high astigmatism in both eyes, and the other had unilateral esotropia. Lens dislocation was found in one student (0.25%) with Marfan syndrome. Retinal vasculitis and optic atrophy were found in one student (0.25%) with systemic lupus erythematosus.ConclusionBecause it is a small, isolated island, Orchid Island still has a unique traditional culture and life style. Therefore the prevalence of myopia in primary school and junior high school students on Orchid Island is low, and 94% of all the students had uncorrected visual acuity above 0.8

Fibrate and the risk of cardiovascular disease among moderate chronic kidney disease patients with primary hypertriglyceridemia

IntroductionHypertriglyceridemia is the most prevalent dyslipidemia in patients with chronic kidney disease (CKD). However, research about fibrate treatment in CKD patients is limited, and assessing its benefits becomes challenging due to the frequent concurrent use of statins. Thus, this study is aimed to investigate the role of fibrate in CKD stage 3 patients with hypertriglyceridemia who did not receive other lipid-lowering agents.MethodsThis study enrolled patients newly diagnosed CKD3 with LDL-C&lt;100mg/dL and had never received statin or other lipid-lowering agents from Chang Gung Research Database. The participants were categorized into 2 groups based on the use of fibrate: fibrate group and non-fibrate group (triglyceride &gt;200mg/dL but not receiving fibrate treatment). The inverse probability of treatment weighting was performed to balance baseline characteristics.ResultsCompared with the non-fibrate group (n=2020), the fibrate group (n=705) exhibited significantly lower risks of major adverse cardiac and cerebrovascular events (MACCEs) (10.4% vs. 12.8%, hazard ratios [HRs]: 0.69, 95% confidence interval [CI]: 0.50 to 0.95), AMI (2.3% vs. 3.9%, HR: 0.52, 95% CI: 0.37 to 0.73), and ischemic stroke (6.3% vs. 8.0%, HR: 0.67, 95% CI: 0.52 to 0.85). The risk of all-cause mortality (5.1% vs. 4.5%, HR: 1.09, 95% CI: 0.67 to 1.79) and death from CV (2.8% vs. 2.3%, HR: 1.07, 95% CI: 0.29 to 2.33) did not significantly differ between the 2 groups.ConclusionThis study suggests that, in moderate CKD patients with hypertriglyceridemia but LDL-C &lt; 100mg/dL who did not take other lipid-lowering agents, fibrates may be beneficial in reducing cardiovascular events

Do beta-adrenergic blocking agents increase asthma exacerbation? A network meta-analysis of randomized controlled trials

Beta-adrenergic blocking agents (abbreviated as beta-blockers) have been used for treating various cardiovascular diseases. However, the potential for asthma exacerbation is one of the major adverse effects of beta-blockers. This study aimed to compare the level of risk for an asthma attack in patients receiving various beta-blockers. We searched for randomized controlled trials (RCTs) of either placebo-controlled or active-controlled design. The current network meta-analysis (NMA) was conducted under a frequentist model. The primary outcome was the incidence of asthmatic attack. A total of 24 RCTs were included. Overall NMA revealed that only oral timolol [risk ratio (RR) = 3.35 (95% confidence interval (CI) 1.04–10.85)] and infusion of propranolol [RR = 10.19 (95% CI 1.29–80.41)] were associated with significantly higher incidences of asthma attack than the placebo, whereas oral celiprolol [RR = 0.39 (95% CI 0.04–4.11)], oral celiprolol and propranolol [RR = 0.46 (95% CI 0.02–11.65)], oral bisoprolol [RR = 0.46 (95% CI 0.02–11.65)], oral atenolol [RR = 0.51 (95% CI 0.20–1.28)], infusion of practolol [RR = 0.80 (95% CI 0.03–25.14)], and infusion of sotalol [RR = 0.91 (95% CI 0.08–10.65)] were associated with relatively lower incidences of asthma attack than the placebo. In participants with a baseline asthma history, in addition to oral timolol and infusion of propranolol, oral labetalol, oxprenolol, propranolol, and metoprolol exhibited significantly higher incidences of asthma attack than did the placebo. In conclusion, oral timolol and infusion of propranolol were associated with a significantly higher risk of developing an asthma attack in patients, especially in those with a baseline asthma history, and should be avoided in patients who present a risk of asthma

Toward controllable and predictable synthesis of high-entropy alloy nanocrystals.

High-entropy alloy (HEA) nanocrystals have attracted extensive attention in catalysis. However, there are no effective strategies for synthesizing them in a controllable and predictable manner. With quinary HEA nanocrystals made of platinum-group metals as an example, we demonstrate that their structures with spatial compositions can be predicted by quantitatively knowing the reduction kinetics of metal precursors and entropy of mixing in the nanocrystals under dropwise addition of the mixing five-metal precursor solution. The time to reach a steady state for each precursor plays a pivotal role in determining the structures of HEA nanocrystals with homogeneous alloy and core-shell features. Compared to the commercial platinum/carbon and phase-separated counterparts, the dendritic HEA nanocrystals with a defect-rich surface show substantial enhancement in catalytic activity and durability toward both hydrogen evolution and oxidation. This quantitative study will lead to a paradigm shift in the design of HEA nanocrystals, pushing away from the trial-and-error approach

Women with endometriosis have higher comorbidities: Analysis of domestic data in Taiwan

AbstractEndometriosis, defined by the presence of viable extrauterine endometrial glands and stroma, can grow or bleed cyclically, and possesses characteristics including a destructive, invasive, and metastatic nature. Since endometriosis may result in pelvic inflammation, adhesion, chronic pain, and infertility, and can progress to biologically malignant tumors, it is a long-term major health issue in women of reproductive age. In this review, we analyze the Taiwan domestic research addressing associations between endometriosis and other diseases. Concerning malignant tumors, we identified four studies on the links between endometriosis and ovarian cancer, one on breast cancer, two on endometrial cancer, one on colorectal cancer, and one on other malignancies, as well as one on associations between endometriosis and irritable bowel syndrome, one on links with migraine headache, three on links with pelvic inflammatory diseases, four on links with infertility, four on links with obesity, four on links with chronic liver disease, four on links with rheumatoid arthritis, four on links with chronic renal disease, five on links with diabetes mellitus, and five on links with cardiovascular diseases (hypertension, hyperlipidemia, etc.). The data available to date support that women with endometriosis might be at risk of some chronic illnesses and certain malignancies, although we consider the evidence for some comorbidities to be of low quality, for example, the association between colon cancer and adenomyosis/endometriosis. We still believe that the risk of comorbidity might be higher in women with endometriosis than that we supposed before. More research is needed to determine whether women with endometriosis are really at risk of these comorbidities

A Study of Hot Cracking Susceptibility during Welding on Incoloy 800H and 825 Superalloys.

本研究係以Incoloy 800H和825鎳基合金為基材，分別針對添加填料與未添加填料進行熱裂紋敏感性特性試驗。利用鎢極惰性氣體遮護電弧銲接法(Gas Tungsten Arc Weld, GTAW)銲接。最後使用鎢極惰性氣體遮蔽電弧銲接進行點狀變應變實驗(Spot Varestraint Test)，觀察鎳基超合金在高溫下受到臨界應變量(CST)對裂紋的影響。另一方面藉由立體顯微鏡、光學顯微鏡觀察裂紋表面組織型態以及X光繞射分析銲道結構，由掃瞄式電子顯微鏡（Scanning Electronic Microscope, SEM）觀察龜裂型態及龜裂破斷面銲道及裂紋分佈之情形，並取合理範圍內並記錄最大龜裂長度（Maximum crack length, MCL）、最大龜裂距離（Maximum crack distance, MCD）及總龜裂長度（Total crack length, TCL）。並利用熱差分析儀(DTA)分析鎳基超合金液/固溫度差值(ΔT)範圍，探討熱龜裂敏感性。 結果顯示鎳基超合金添加填料在高溫下，龜裂敏感性低於未添加填料母材，其中以添加Inconel 82填料對熱龜裂敏感性影響較低，根據這些銲接數據可以得材料之熱龜裂敏感性與液/固溫度差值(ΔT)範圍相關性，裂紋總長度越長，熱分析顯示之液/固溫度差值(ΔT)範圍也越大，熱龜裂敏感性越高。裂紋形貌在金相上顯示分別有(a)熔池內沿晶裂紋，(b)熔池內之凝固裂紋，(c)銲道熱影響區之沿晶裂紋，(d)基材熱影響區之穿晶裂紋。根據裂紋形貌可推測出材料高溫下發生龜裂之過程與情形，在SEI與BEI圖像下觀察裂紋周圍可能產生之析出物，並以EDS分析周圍組織成分，結果顯示出Incoloy 鎳基合金在高溫下並無低溫相析出物產生，在在顯示出是由於變應變試驗將基材臨界應變提升至脆性溫度範圍區間，而高溫下脆性溫度範圍越大則代表熱龜裂敏感性越高，結果顯示Incoloy 800H鎳基合金熱龜裂敏感性最高。In this study, the hot cracking susceptibility of the Incoloy 800H and 825 nickel-base alloy substrate was discussed with filler and without filler. And later nickel alloy of filler 52 and 82 Tungsten inert gas shielded arc welding in the specimen. Observation of nickel based superalloy at high temperature by the critical strain for crack. On the other hand by using a stereoscopic microscope, optical microscope observation of the crack surface type of organization, as well as X-ray diffraction analysis of the weld structure, observed by scanning electron microscopy. The maximum crack length, amount of cracks, and total cracks length were recorded. The difference of liquid and solid (ΔT) was analyzed in nickel-based superalloy using differential thermal analysis (DTA) and then examine the relationship between cracks and the hot cracking sensitivity. The results showed that the hot cracking sensitivity of the nickel-based super-alloys with filler at high temperature was lower than that without filler base metal. The hot cracking sensitivity had a slight effect with the Inconel 82 filler addition. According to experimental data, the relationshop between the hot cracking susceptibility and the liquid-solid two-phase range can be obtained. When the crack total length was increased, the liquid-solid two-phase range is higher and then the hot cracking susceptibility was raised. The morphologies of cracks included the intergranular crack in the molten pool, the molten pool solidification cracking, the weld heat-affected zone of intergranular cracks, and the transgranular crack in the heat-affected zone. The occurrence of cracking in materials under high temperature can be inferred according to the morphologies of cracks. The results showed that no low temperature precipitates under high temperature incoloy nickel-based alloys. This was because that a critical strain increased to the range of the brittle temperature range rature in base metal during the varistraint test. When the brittle temperature range was higher under high temperature, hot cracking sensitivity was more obvious. The results displayed the hot cracking sensitivity was most evident in Incoloy 800H alloys of all the nickel-based alloys.致謝 i 摘要 ii Abstract iii 總目錄 v 表目錄 vii 圖目錄 viii 第一章 前言 1 第二章 文獻回顧 4 2.1. 鎳合金的應用 4 2.1.2. 鎳鐵基合金應用 10 2.1.3. 鎳鐵基銲接性 16 2.1.4. Incoloy 800H & 825鐵基鎳合金【15】 19 2.2. 銲接熱裂紋 21 2.2.1. 裂紋的種類 22 2.2.2. 熱裂紋原理 30 2.4. 熱分析 38 第三章 實驗步驟與方法 42 3.1 實驗流程 42 3.2 試片製備 43 3.2.1 基材準備與設計 43 3.2.2 銲接參數 47 3.2.3 可調式變應變設備 48 3.3 基材與銲道成分分析 50 3.3.1 分析儀器 50 3.3.2 分析方法 50 3.4 基材與銲道結構與組織分析 52 3.4.1試片觀察 52 3.4.2熱裂紋巨觀分析 52 3.4.3 光學顯微鏡觀察 53 3.4.4 X光繞射分析 53 3.4.5 SEM觀察 54 3.5 機械性質分析 54 3.5.1銲道橫截面硬度測定 54 3.5.2 拉伸實驗 54 3.6 熱分析 55 第四章 結果與討論 56 4.1基材分析 56 4.1.1 試片與銲道外觀 56 4.1.2 金相觀察 61 4.1.3 X光繞射分析 74 4.1.4 微小硬度試驗 75 4.1.5 拉伸試驗 76 4.2材料熱分析 79 4.3 裂紋分析與統計 85 4.3.1 裂紋數量 92 4.3.2 裂紋平均長度 94 4.3.3 最大裂紋長度 97 4.3.4 總裂紋長度 100 4.4 裂紋組織與SEM分析 103 4.4.1 裂紋表面組織分析 103 4.4.2 裂紋截面組織分析 110 第五章 結論 117 第六章 參考文獻 11