膏盐层氧化障在长江中下游玢岩铁矿成矿中的作用

长江中下游是我国著名的铁铜金等多金属成矿带，其中宁芜和庐枞盆地产出一系列与白垩纪中基性火山-次火山岩有关的玢岩铁矿床。前人根据玢岩铁矿的地质特征、空间分布规律及其与火山-次火山岩的关系建立了著名玢岩铁矿成矿模式，发展了成矿理论，有效指导了玢岩铁矿找矿工作。但三叠系膏盐层在成矿中的作用没有引起应有的重视，深部矿化基本没有涉及。最新研究和勘查结果揭示中下三叠统周冲村组顶部膏盐层与矿化关系密切，但膏盐层的控矿机理还不清楚，“膏盐层氧化障”在玢岩铁矿成矿中的作用鲜有报道，宁芜-庐枞盆地深部矿化类型和矿体赋存部位知之甚少。本文研究了长江中下游玢岩铁矿的硫同位素组成，探讨了膏盐层氧化障在玢岩铁矿成矿中的作用。宁芜和庐枞盆地玢岩铁矿、硫铁矿中普遍含有石膏，玢岩铁矿、硫铁矿和石膏矿三者密切共生。玢岩铁矿及伴生硫铁矿中黄铁矿的δ^34 Sv-CDT值异常高，平均值均在5‰以上，石膏的δ^34SV-CDT，值大部分位于20％。左右，与海相硫酸盐的值相似，指示矿床中硫主要来自三叠纪膏盐层。矿床中黄铁矿的硫同位素组成与矿床成因类型密切相关。宁芜盆地姑山矿田的δ^34 SV-CDT值最高，为10．8‰，梅山矿田次之，为7．85‰，凹山矿田最低，为5．01‰；矿床成因类型也发生相应变化，矿浆型→矿浆→热液型→热液型。矿床中黄铁矿的硫同位素变化主要由硫酸盐的还原温度和原始岩浆硫所占比例不同引起，还原温度越高，δ^34S值越高；原始岩浆硫所占比例越高，δ^34S值越低。计算结果表明矿床中约60％-80％的硫来自膏盐层硫酸盐的还原，还原温度多在450℃以上，但硫化物的沉淀温度相对较低，就位时间稍晚。提出膏盐层（富含碳酸盐、石膏和石盐等）不仅可以为成矿提供大量Na＋、Cl-、CO3^2-等矿化剂，使围岩发生钠长石化、方柱石化（氯化）和矽卡岩化等蚀变，使Fe^2＋以NaFeCl3等络合物形式搬运，膏盐层还是地壳深处最重要的氧化障，能够将硅酸盐熔体和成矿溶液中的Fe^2＋氧化成Fe^3＋,富集形成铁矿床，是玢岩铁矿成矿的关键因素。当炽热的岩浆与膏盐层（CaSO4）发生同化混染时，SO4^2-将硅酸盐熔体中的Fe^2＋氧化成Fe^3＋，Fe^3＋无法进入硅酸盐矿物晶格之中，而形成铁氧化物Fe2O4／Fe2O3和贫铁的硅酸盐矿物透辉石／阳起石、透闪石等。铁氧化物在磷、水和氯化钠等盐类物质的作用下在岩浆房中与硅酸盐熔体发生液态不混熔，熔离形成铁矿浆。铁矿浆粘滞性强，迁移距离不远，在岩体与膏盐层的接触带附近，沿构造有利部位贯入，形成姑山、梅山等矿浆型铁矿床。以铁的络合物形式搬运的成矿热液流动性强，迁移距离远，可以在远离岩体与膏盐层接触带部位、在上部白垩纪火山岩中富集沉淀。长江中下游玢岩铁矿中矿浆充填型和热液交代-充填型矿体同时存在，二者在空间上具有明显的分带，具“双层成矿结构”。在盆地深部岩体与膏盐层的接触部位产出“大冶式”矿浆充填一接触交代型富铁矿床，规模可能超过了赋存于浅部火山-次火山中的狭义“玢岩铁矿”。位于宁芜盆地南北两端的娃山和梅山矿田是找寻“大，台式”矿浆充填-接触交代型富铁矿的有利地段。在SO4^2-氧化Fe^2＋的同时自身被还原为S^2-，S^2-与Fe^2＋结合形成硫铁矿，在铁矿的上部或边部富集形成硫铁矿矿床；这是石膏矿、铁矿和硫铁矿密切共生的根本原因。

氧化还原障在热液铀矿成矿中的作用

铀是变价元素,氧化还原条件控制铀的迁移和沉淀。铀在氧化环境中呈U^(6+)形式存在,在还原条件下则以U^(4+)形式存在。氧化态六价铀主要以可溶的碳酸铀酰/氟化铀酰络合物形式在水溶液中迁移,还原态四价铀主要以沥青铀矿和铀石等形式富集沉淀成矿。热液铀矿的形成需要一对空间上密切共生的氧化障/氧化剂和还原障/还原剂,二者缺一不可。首先,氧化障中氧化剂将富铀岩石中的铀大量氧化形成U^(6+),溶解进入水溶液迁移;第二,高氧化性富铀溶液遇到还原障,U^(6+)还原成U^(4+)沉淀下来,富集形成铀矿。前人虽然对铀的地球化学性质及氧化还原反应在铀成矿中作用已比较了解,但如何在实际铀矿成矿系统中准确识别氧化还原障,有效利用氧化还原障的控矿机理指导找矿,还存在一些模糊认识,制约了铀成矿理论的发展和找矿方法的提升。本文以我国最重要的砂岩型铀矿、火山岩型铀矿、花岗岩型铀矿和变质型铀矿为例,总结了与铀矿化有关的氧化还原障的主要类型,探讨了红层等蒸发盐地层(氧化障),有机质、煌斑岩等中基性岩脉(还原障)与铀矿之间的关系及控矿机制,揭示了成矿盆地中铀-煤、铀-气(油)共生的机制,阐明了翁泉沟硼、铁、铀矿共生原因,建立了不同类型铀矿成矿模型。

氧化还原障在热液铀矿成矿中的作用

文章以热液铀矿成矿研究的意义为出发点,接着分析了热液矿床的概述,进而根据实际情况对进行了探究。

云南金平长安金矿地球化学障及找矿意义

通过对V5矿体群地球化学障分析探索有效的找矿思路,认为导致V5矿体群富集沉淀的地球化学障主要为构造障、碳酸岩障及氧化/还原障。寻找类似的地球化学障寻求找矿的突破。

膏盐层在矽卡岩型铁矿成矿中的作用

矽卡岩型铁矿是我国富铁矿的重要类型,约占全国富铁矿总储量的60%。虽然膏盐层与矽卡岩型铁矿的关系已引起部分矿床学家的关注,但膏盐层的控矿机制尚不清楚。本文以我国最重要的大冶式和邯邢式矽卡岩型铁矿为例,探讨了膏盐层在矽卡岩型铁矿成矿中的作用。膏盐层富含碳酸盐、石膏和石盐等,不仅可以为成矿提供大量Na^+、Cl^-、CO3^(2+)等矿化剂,使围岩发生钠长石化、方柱石化(氯化)和矽卡岩化等蚀变,使Fe^(2+)以NaFe-Cl等络合物形式搬运,膏盐层还是地壳深处最重要的氧化障,能够将硅酸盐熔体和成矿溶液中的Fe^(2+)氧化成Fe^(3+),富集形成铁矿床,是矽卡岩型铁矿成矿的关键因素。大冶地区的膏盐层属于中三叠统下部的嘉陵江组,邯邢地区的膏盐层属于中奥陶统马家沟组—峰峰组。大冶和邯邢式矽卡岩型铁矿中硫化物的δ^(34)S_(V-CDT)值异常高,计算结果表明矿床中约80%的硫来自膏盐层硫酸盐的还原,还原温度多在500℃以上,但硫化物的沉淀温度相对较低,就位时间稍晚;硫酸盐的δ^(34)S_(V-CDT)值和还原温度越高,硫化物的δ^(34)S_(V-CDT)值越高,原始岩浆硫所占比例越高,硫化物的δ^(34)S_(V-CDT)值越低。当炽热的岩浆与膏盐层(CaSO_4)发生同化混染时,SO_4^(2-)将硅酸盐熔体中的Fe^(2+)氧化成Fe^(3+),Fe^(3+)无法进入硅酸盐矿物晶格,而形成Fe_3O_4/Fe_2O_3进入熔体,铁氧化物在磷、氯化钠、水等挥发分和盐类物质的作用下在岩浆房中与硅酸盐熔体发生不混熔,形成铁矿浆,沿构造有利部位贯入,形成矿浆型铁矿床。在矽卡岩型铁矿床中,矿浆充填型和热液交代型矿体同时存在,二者在空间上具有一定的分带性,有时渐变过渡,矿浆充填型铁矿体通常位于深部靠近成矿岩体的部位,而热液交代型铁矿体位于成矿流体运移的前方。在SO_4^(2-)氧化Fe^(2+)的同时自身被还原为S^(2-),与Fe^(2+)结合形成硫铁矿,分布在铁矿的上部或边部。

膏盐层在Ni-Cu-PGE硫化物矿床成矿中的作用——以俄罗斯诺里尔斯克矿床为例

与基性-超基性侵入体有关的Ni-Cu-PGE硫化物矿床是镍-铜-铂族元素矿床的最重要类型。传统观点认为,Ni-Cu-PGE硫化物矿床是由成矿岩浆分异演化、熔离形成的,与围岩性质关系不大。实际上,大部分基性-超基性岩浆是硫化物不饱和的,在岩浆自身演化过程中难以聚集大量硫化物而形成有经济价值的大型高品位Ni-Cu-PGE硫化物矿床。因此,壳源硫的加入是基性-超基性岩浆中硫化物浓度达到过饱和,熔离形成Ni-Cu-PGE硫化物矿床的关键。膏盐层是富含石膏等硫酸盐(SO4^2-)的蒸发沉积建造,除SO4^2-外,还富含Cl^-、CO3^2-、Na^+、K+等盐类物质,在自然界分布广、面积大,是地壳中重要的硫源层和氧化障。但膏盐层在Ni-Cu-PGE硫化物矿床中的作用长期被忽视,制约了Ni-Cu-PGE硫化物矿床成矿找矿理论的发展。文章以世界最大的俄罗斯诺里尔斯克Ni-Cu-PGE硫化物矿床为例,介绍了膏盐层与矿床分布的空间关系、石膏等硫酸盐矿物在矿床和蚀变围岩中的分布、成矿元素和硫同位素组成特征及变化规律,阐明了膏盐层在成矿中的作用和控矿机理。膏盐(SO4^2-)的加入,可以大幅度提高成矿系统的氧逸度,将成矿岩浆中Fe^2+氧化成Fe^3+,形成铁氧化物,SO4^2-自身被还原,向成矿系统提供还原硫S^2-,与Cu^+、Ni^2+等结合,形成铜镍硫化物等,使基性-超基性成矿岩浆由硫化物不饱和变为过饱和,形成硫化物小液滴,在岩浆房经聚集-熔离-富集,形成岩浆型Ni-Cu-PGE硫化物矿床。除膏盐层外,富含硫化物的地层也是形成Ni-Cu-PGE硫化物矿床的重要硫源层。

Enhancing high-temperature oxidation resistance of nickel superalloy obtained by laser powder bed fusion via reactive electric spark treatment

The high-temperature oxidation resistance of the nickel superalloy prepared by the laser powder bed fusion(LPBF)has been significantly increased as a result of in-situ formation of a thermal barrier layer(α-Al_(2)O_(3)+CaMoO4)during oxidative annealing of surface layers modified by electric spark treatment(EST).The reactive EST of the LPBF-built items based on nickel EP741NP alloy was carried out with low-melting Al−12%Si,Al−6%Ca−0.6%Si and Al−7%Ca−1%Mn electrodes.It was found that under EST done by Al−7%Ca−1%Mn electrode an intermetallic(β-NiAl+γ'-Ni3Al)15μm-thick layer reinforced by spherical oxide(CaMe)O nanoparticles was formed.Formation of that structure increases the wear resistance of LPBF nickel superalloy by 4.5 times.Further oxidative annealing at 1000°C leads to a formation of continuous two-layered coating with an inner layer ofα-Al_(2)O_(3) and an outer layer of CaMoO4,which together act as an effective barrier preventing the diffusion of oxygen into the bulk of the superalloy.

Impedance spectroscopy study of high-temperature oxidation of Gd_2O_3-Yb_2O_3 codoped zirconia thermal barrier coatings

3Gd2O3-3Yb2O3-4Y2O3 （mole fraction, %） co-doped ZrO2 （GY-YSZ） thermal barrier coatings （TBCs） were produced by electron beam physical vapor deposition （EB-PVD）. The oxidation behavior of GY-YSZ at 1 050 ℃ was investigated using impedance spectroscopy （IS） combined with scanning electron microscopy （SEM）, Raman spectroscopy and X-ray diffractometry （XRD）. Various electrical responses observed in the impedance spectra corresponding to GY-YSZ grains and grain boundaries were explained using circuit modeling. The change in the conduction mechanism of GY-YSZ was found to be related to the O^2- vacancy and lattice distortion due to the stabilizer diffusion during the oxidation. The results also suggested that the specific oxidation information about the GY-YSZ grains and grain boundaries should be acquired at a moderate measurement temperature, which was related to the resistance value in the impedance spectra. The resistance values of the GY-YSZ grains and grain boundaries should be measured at 200 ℃ and 300 ℃, respectively.

Parthenolide protects human lens epithelial cells from oxidative stress-induced apoptosis via inhibition of activation of caspase-3 and caspase-9

The apoptosis of lens epithehal cells has been proposed as the common basis of cataract formation, with oxidative stress as the major cause. This study was performed to investigate the protective effect of the herbal constituent parthenolide against oxidative stress-induced apoptosis of human lens epithelial （HLE） cells and the possible molecular mechanisms involved. HLE cells （SRA01-04） were incubated with 50 μM H2O2 in the absence or presence of different doses of parthenolide （10, 20 and 50 μM）. To study apoptosis, the cells were assessed by morphologic examination and Annexin V-propidium iodide double staining flow cytometry; to investigate the underlying molecular mechanisms, the expression of caspase-3 and caspase-9 were assayed by Western blot and quantitative RT-PCR, and the activities of caspase-3 and caspase-9 were measured by a Chemicon caspase colorimetric activity assay kit. Stimulated with H202 for 18 h, a high fraction of riLE cells underwent apoptosis, while in the presence ofparthenolide of different concentrations, dose-dependent blocking of HLE cell apoptosis was observed. The expression of caspase-3 and caspase-9 induced by H202 in HLE cells was significantly reduced by parthenolide both at the protein and mRNA levels, and the activation ofcaspase-3 and caspase-9 was also suppressed by parthenolide in a dose-dependent manner. In conclusion, parthenolide prevents HLE cells from oxidative stress-induced apoptosis through inhibition of the activation ofcaspase-3 and caspase-9, suggesting a potential protective effect against cataract formation.

Improvement of thermally grown oxide layer in thermal barrier coating systems with nano alumina as third layer

A thermally grown oxide （TGO） layer is formed at the interface of bond coat/top coat. The TGO growth during thermal exposure in air plays an important role in the spallation of the ceramic layer from the bond coat. High temperature oxidation resistance of four types of atmospheric plasma sprayed TBCs was investigated. These coatings were oxidized at 1000 °C for 24, 48 and 120 h in a normal electric furnace under air atmosphere. Microstructural characterization showed that the growth of the TGO layer in nano NiCrAlY/YSZ/nano Al2O3 coating is much lower than in other coatings. Moreover, EDS and XRD analyses revealed the formation of Ni（Cr,Al）2O4 mixed oxides （as spinel） and NiO onto the Al2O3 （TGO） layer. The formation of detrimental mixed oxides （spinels） on the Al2O3 （TGO） layer of nano NiCrAlY/YSZ/nano Al2O3 coating is much lower compared to that of other coatings after 120 h of high temperature oxidation at 1000 °C.

Potential beneficial effects of butyrate in intestinal and extraintestinal diseases

The multiple beneficial effects on human health of the short-chain fatty acid butyrate,synthesized from nonabsorbed carbohydrate by colonic microbiota,are well documented.At the intestinal level,butyrate plays a regulatory role on the transepithelial fluid transport,ameliorates mucosal inflammation and oxidative status,reinforces the epithelial defense barrier,and modulates visceral sensitivity and intestinal motility.In addition,a growing number of studies have stressed the role of butyrate in the prevention and inhibition of colorectal cancer.At the extraintestinal level,butyrate exerts potentially useful effects on many conditions,including hemoglobinopathies,genetic metabolic diseases,hypercholesterolemia,insulin resistance,and ischemic stroke.The mechanisms of action of butyrate are different;many of these are related to its potent regulatory effects on gene expression.These data suggest a wide spectrum of positive effects exerted by butyrate,with a high potential for a therapeutic use in human medicine.

Obesity promotes oxidative stress and exacerbates blood-brain barrier disruption after high-intensity exercise

Purpose: The purpose of this study was to investigate the effects of obesity and high-intensity acute exercise on oxidant-antioxidant status,neurotrophic factor expression, and blood-brain barrier(BBB) disruption.Methods: Twenty-four healthy, untrained men(12 non-obese(mean 14.9% body fat) and 12 obese subjects(mean 29.8% body fat)) performed20 min of continuous submaximal aerobic exercise at 85% maximal oxygen consumption. Blood sampling was performed to examine the oxidant-antioxidant status(reactive oxygen species(ROS) and superoxide dismutase(SOD)), neurotrophic factors(brain-derived neurotrophic factor(BDNF) and nerve growth factor(NGF)), and BBB disruption(S100β and neuron-specific enolase) before and after acute exercise.Results: The obese group showed significantly higher pre-exercise serum ROS levels and significantly lower pre-exercise serum SOD levels than the non-obese group(p < 0.05). Serum ROS, SOD, BDNF, NGF, and S100β levels were significantly increased post-exercise compared with pre-exercise levels in both the non-obese and the obese groups(p < 0.05). The obese group showed significantly higher serum ROS, BDNF, NGF,and S100β levels post-exercise compared to the non-obese group(p < 0.05).Conclusion: Our study suggests that episodic vigorous exercise can increase oxidative stress and blood neurotrophic factor levels and induce disruption of the BBB. Moreover, high levels of neurotrophic factor in the blood after exercise in the obese group may be due to BBB disruption,and it is assumed that oxidative stress was the main cause of this BBB disruption.

Is there any link between homocysteine and atherosclerosis？

I have read with interest the paper by Hart, et al. re- porting that homocysteine （Hey） is an independent risk fac- tor for non-culprit coronary lesions progression after 12 months of follow-up in elderly patients who has undergone percutaneous coronary stenting. Hcy-mediated increased lipid peroxidation and generation of free radicals results in in- flammation and endothelial dysfunction, which triggers atherosclerotic process. Coronary artery disease is also as- sociated with higher levels of Hcy.

Phosphodiesterase-3 inhibitor （cilostazol） attenuates oxidative stress-induced mitochondrial dysfunction in the heart

Background Cilostazol is a type 3 phosphodiesterase inhibitor which has been previously demonstrated to prevent the occurrence of tachyarrhythmia and improve defibrillation efficacy. However, the mechanism for this beneficial effect is still unclear. Since cardiac mito-chondria have been shown to play a crucial role in fatal cardiac arrhythmias and that oxidative stress is one of the main contributors to arr-hythmia generation, we tested the effects of cilostazol on cardiac mitochondria under severe oxidative stress. Methods Mitochondria were isolated from rat hearts and treated with H2O2 to induce oxidative stress. Cilostazol, at various concentrations, was used to study its protective effects. Pharmacological interventions, including a mitochondrial permeability transition pore （mPTP） blocker, cyclosporine A （CsA）, and an inner membrane anion channel （IMAC） blocker, 4＇-chlorodiazepam （CDP）, were used to investigate the mechanistic role of cilostazol on cardiac mitochondria. Cardiac mitochondrial reactive oxygen species （ROS） production, mitochondrial membrane potential change and mi-tochondrial swelling were determined as indicators of cardiac mitochondrial function. Results Cilostazol preserved cardiac mitochondrial function when exposed to oxidative stress by preventing mitochondrial depolarization, mitochondrial swelling, and decreasing ROS produc-tion. Conclusions Our findings suggest that cardioprotective effects of cilostazol reported previously could be due to its prevention of car-diac mitochondrial dysfunction caused by severe oxidative stress.

Analysis on produce mechanism and influence factor of CO gas on the coal exploitation working face

Summarized the four main sources of CO gas on the working face based on investigation and local observation: firstly,it analyzed the mechanism that CO gas was produced by spontaneous combustion and oxygenation of gob residual coal;next,it illus- trated the theory that special coal seam deposits natural CO gas,and provided correlative experiment data;and then,it illustrated the reason of the CO gas in working face in- creased relatively in the course of coal cutter's shearing,according to the translation be- tween mechanism energy and inner energy and the rupture of carbon molecule side chain during coal exploitation;lastly,illustrated the reason of CO gas appearance and the rela- tively release quantity during coal mine blasting underground.We find out the source of CO gas on the working face accurately,and provide advantages for appropriate prevention and practical management measures.

Effect of Lianshu preparation on lipopolysaccharide-induced diarrhea in rats

AIM： To investigate the effect of Lianshu preparation on lipopolysaccharide （LPS）-induced diarrhea in rats. METHODS： A diarrhea model was established in Sprague Dawley rats via injection of 1 mL of 30 mg/kg LPS. A total of 40 rats were randomly divided into normal group, LPS group, LPS ＋ Lianshu group, LPS ＋ berberine group （n = 10 in each group）. Their intestinal mucosal barrier and frequency of diarrhea were observed. Levels of glucose, serum Na^＋, K^＋, Cl and hematocrit, plasma nitrogen monoxide （NO）, diamine oxidase （DAO）, and D （-）-lactate were measured. The number of IgA＋ plasma cells in small intestine was detected and SIgA levels in the intestinal fluid were measured. The antipyretic activity of Lianshu preparation in rats was evaluated using Brewer＇s yeast-induced pyrexia （10 mL/kg of 20% aqueous suspension）. Acetaminophen （250 mg/kg, intragastric administration, bid） was comparison. Temperature used as a standard drug for was recorded 1 h before and 6 h after Brewer＇s yeast injection. Finally, small intestina transmission in mice treated with Lianshu was detected after intraperitoneal injection of methyl prostigmin （2 mg/kg）. Atropine （10 g/kg） was used as a control. The ink content in intestine was determined and the total length of intestine was measured. RESULTS： The frequency of diarrhea was higher in LPS group than in LPS ＋ Lianshu group and LPS ＋ berberine group （36.70± 5.23 vs 28.50 ±4.06 and 32.70±9.30 respectively, P 〈 0.01）, and lower in LP5 ＋ Lianshu group than in LPS ＋ berberine group （P = 0.03）. The levels of Na＋, glucose, Cl, K^＋ were significantly lower in LPS ＋ Lianshu group than in LPS ＋ berberine group （140.35±3.19 mmol/L vs 131.99±4.86 mmol/L, 8.49 ±1.84 mmol/L vs 6.54±2.30 mmol/L, 106.29± 4.41 mmol/L vs 102.5±1.39 mmol/L, 5.08±0.66 mmol/L vs 4.32 ± 0.62 mmol/L respectively, P 〈 0.05）. The level of hematocrit was lower in LPS ＋ Lianshu group than in LPS ＋ berberine group （0.50% ±0.07% vs 0.59%± 0.10% respectively, P 〈 0.05）. The plasma levels of NO, DAO and D （-）-lactate were higher in LPS group than in normal group （79.74 ± 7.39μmol/L vs 24.94 ± 3.38μmol/L, 2.48 ±0.42μ/mL vs 0.82 ±0.33 p/mL, 5.63± 0.85μg/mL vs 2.01 ±0.32 μg/mL respectively, P 〈 0.01）, and lower in LPS ＋ Lianshu group than in LP5 ＋ berberine group （48.59±4.70μmol/L vs 51.56 ±8.38 μmol/L, 1.43± 0.53μmol/mL vs 1.81 ±0.42 μmol/mL, 4.00± 0.54 μg/mL vs 4.88 ± 0.77 pg/mL respectively, P 〈 0.05）. The morphology of the intestinal mucosa showed destroyed villi in LPS group and atrophied intestinal mucosa in other groups. The pathological intestinal mucosal changes were less in LPS ＋ Lianshu group than in LPS group. The number of IgA＋ plasma cells and amount of SIgA were higher in LPS ＋ Lianshu group than in LPS group （1.16±0.19/μm^2 vs 1.09±0.28/μm^2, P = 0.026; 0.59 ±0.12 mg/L vs 0.15± 0.19 mg/L respectively, P = 0.000）. Lianshu had counteractive effects on yeast-induced pyrexia and enterokinesia in rats. CONCLUSION： Lianshu preparation has therapeutic effects on LPS-induced diarrhea and enterokinesia in rats.

Thermal properties of glass-ceramic bonded thermal barrier coating system

The thermal properties of a thermal barrier coating （TBC） system comprised of BaO-MgO-SiO_2 based glass-ceramic bond coating, 8% （mass fraction） yttria stabilized zirconia （8YSZ） top coating and nimonic alloy substrate were evaluated. The thermal diffusivity and thermal conductivity of the TBC coated substrate were lower than those of bare substrate and glass-ceramic coated substrate under identical conditions. The specific heat capacity, thermal diffusivity and thermal conductivity of the TBC coated substrate increase with the increase of the temperature. Further, it is observed that the thermal conductivity of the TBC system decreases with the increase in the top coating thickness.

Bile-acid-induced cell injury and protection

Several studies have characterized the cellular and molecular mechanisms of hepatocyte injury caused by the retention of hydrophobic bile acids （BAs） in cholestatic diseases. BAs may disrupt cell membranes through their detergent action on lipid components and can promote the generation of reactive oxygen species that, in turn, oxidatively modify lipids, proteins, and nucleic acids, and eventually cause hepatocyte necrosis and apoptosis. Several pathways are involved in triggering hepatocyte apoptosis. Toxic BAs can activate hepatocyte death receptors directly and induce oxidative damage, thereby causing mitochondrial dysfunction, and induce endoplasmic reticulum stress. When these compounds are taken up and accumulate inside biliary cells, they can also cause apoptosis. Regarding extrahepatic tissues, the accumulation of BAs in the systemic circulation may contribute to endothelial injury in the kidney and lungs. In gastrointestinal cells, BAs may behave as cancer promoters through an indirect mechanism involving oxidative stress and DNA damage, as well as acting as selection agents for apoptosis-resistant cells. The accumulation of BAs may have also deleterious effects on placental and fetal cells. However, other BAs, such as ursodeoxycholic acid, have been shown to modulate BA-induced injury in hepatocytes. The major beneficial effects of treatment with ursodeoxycholic acid are protection against cytotoxicity due to more toxic BAs; the stimulation of hepatobiliary secretion; antioxidant activity, due in part to an enhancement in glutathione levels; and the inhibition of liver cell apoptosis. Other natural BAs or their derivatives, such as cholyI-N- methylglycine or pharmacological properties. cholylsarcosine, interest owing have also aroused to their protective

High dimension feature extraction based visualized SOM fault diagnosis method and its application in p-xylene oxidation process

Purified terephthalic acid(PTA) is an important chemical raw material. P-xylene(PX) is transformed to terephthalic acid(TA) through oxidation process and TA is refined to produce PTA. The PX oxidation reaction is a complex process involving three-phase reaction of gas, liquid and solid. To monitor the process and to improve the product quality, as well as to visualize the fault type clearly, a fault diagnosis method based on selforganizing map(SOM) and high dimensional feature extraction method, local tangent space alignment(LTSA),is proposed. In this method, LTSA can reduce the dimension and keep the topology information simultaneously,and SOM distinguishes various states on the output map. Monitoring results of PX oxidation reaction process indicate that the LTSA–SOM can well detect and visualize the fault type.

Influence of heat treatment on nanocrystalline zirconia powder and plasma-sprayed thermal barrier coatings

Nanostructured zirconia top coat was deposited by air plasma spray and NiCoCrAlTaY bond coat was deposited on Ni substrate by low pressure plasma spray.Nanostructured and conventional thermal barrier coatings were heat-treated at temperature varying from 1050 to 1 250oC for 2-20 h.The results show that obvious grain growth was found in both nanostructured and conventional thermal barrier coatings(TBCs)after high temperature heat treatment.Monoclinic/tetragonal phases were transformed into cubic phase in the agglomerated nano-powder after calcination.The cubic phase content increased with increasing calcination temperature.Calcination of the powder made the yttria distributed on the surface of the nanocrystalline particles dissolve in zirconia when grains grew.Different from the phase constituent of the as-sprayed conventional TBC which consisted of diffusionlesstransformed tetragonal,the as-sprayed nanostructured TBC consisted of cubic phase.