饮食维生素K对华法林抗凝稳定性的影响

饮食维生素K摄入量的变化是造成口服华法林患者国际标准化比值(INR)异常波动的主要原因之一。对于口服华法林患者应该如何摄入维生素K,临床医师给出的意见一直比较模糊。过去许多患者被告知应“限制或避免食用富含维生素K的食物,包括绿叶蔬菜类”,这可能导致他们的维生素K摄入量偏低。近年来的研究和循证医学证据表明,华法林抗凝稳定性差与低维生素K摄入量有关;稳定保持较高水平的维生素K日摄入量(>100 μg/d)可降低无法解释的华法林剂量-反应关系个体内变异发生率,减少INR的异常波动,提高抗凝治疗的稳定性。     

高导热金刚石/铝复合材料的真空热压制备

以纯铝粉末和金刚石为基体材料,采用真空热压固相烧结方式制备出热导率为677 W/(m·K)的高导热金刚石/铝复合材料。利用激光导热仪、热膨胀仪对金刚石/铝复合材料性能进行表征,并通过对制备温度、保温时间及金刚石基本颗粒尺寸的调控来优化制备工艺。研究发现:随制备温度升高,金刚石/铝复合材料的密度及致密度均有所提高,其热导率呈先升后降的趋势,当制备温度为650 ℃时,热导率达到526.2 W/(m·K)。随着保温时间由30 min增加至120 min,金刚石/铝复合材料的密度、致密度和热导率均增大,致密度达到99.1%,热导率达到566.7 W/(m·K)。当金刚石基本颗粒尺寸由20 μm增加至500 μm时,金刚石/铝复合材料的密度、致密度先增大后减小;在金刚石基本颗粒尺寸为200 μm时,密度达到最大,分别为3.06 g/cm3和98.4%;热导率随金刚石基本颗粒尺寸逐渐增大,在金刚石基本颗粒尺寸为500 μm时,热导率达到677.5 W/(m·K),为目前最高增强效率。故通过工艺控制可以有效提高铝基体与金刚石的结合,减少其界面空隙,进而制备出高热导率金刚石/铝复合材料。      

Distribution characteristics and environmental risk assessment following metal(loid)s pollution incidents at Southwest China mining site

Limited information is available on long-term effects of metal(loid)s pollution incidents. Here, we analyze the distribution characteristics and quantification of elements in the Southwest China Keda mining site, which is one of the most populated sites and enables human health and ecological risk assessments of elemental pollution. The results on modified degree of contamination indicated that the soil and sediment were highly contaminated near Dahu Lake. The health risk of children was almost 2.5 times that of adults in surface water, and 7.1 times in soil, respectively. Moreover, Tl and As were the main health risk contributors in surface water and soil, respectively, and As posed the highest ecological risk both in soil and sediment. These results indicated the potential impact of toxic metal(loid)s on the health of residents and environment. Hence, more scientific attention and proper management need to be paid to this environmental challenge in the future.     

肾移植术后受者环孢素的血药浓度监测

目的 观察环孢素血药浓度与肾移植效果间关系。方法 对97例接受同种异体肾脏移植术受者术后8周内206例次环孢素血药浓度监测结果进行回顾性分析,按照受者术后的临床表现、生化指标将其分为术后正常组、急性排斥组、急性毒性组,采用荧光偏振免疫测定法,以单克隆抗体试剂测定环孢素血药浓度。结果 术后正常组 62例移植肾功能良好,环孢素的给药剂量为5.2±1.9mg/kg·d,171例次环孢素血药浓度的平均值为309.85±131.69 μg/L;术后急性排斥组26例,距发生排斥反应最近一次的环孢素血药浓度平均为165.80±123.13μg/L,环孢素的给药剂量为4.8±1.6mg/kg·d;术后急性毒性组9例,距发生毒性反应最近一次的环孢素血药浓度平均为556.51±102.50μg/L,环孢素的给药剂量为6.2±1.0mg/kg·d。三组之间环孢素的给药剂量无显著性差异(P>0.05),但环孢素血药浓度却相差很大,两两之间有显著性差异(正常组与排斥组P<0.05;正常组与毒性组P<0.05;排斥组与毒性组P<0.01)。结论 环孢素浓度较低时,出现排斥反应的可能性较大;而环孢素浓度较高时,发生毒性反应的机会较多。     

Spectrofluorimetric determination of trace amounts of cadmium with 2,4-dihydroxyacetophenone benzoylhydrazone

1. Introduction Cadmium is a highly toxic and one of the most dangerous trace elements. Spectrofluorimetry has many advantages such as high sensitivity. Cadmium has been determined spectrofluorimetrically [1-8]. Previously, several hydrazones have been used as spectrofluorimetric reagents for the determination of aluminium [9-10], gallium [11], copper [12-13], ber-illium [14], zinc [15], scandium [16], and molybde-num [17]. However, no work has been done on the determination of cadmium with h…     

核级316NG控氮奥氏体不锈钢的局部腐蚀行为

采用电化学测试法、点腐蚀试验法、盐雾腐蚀试验法和慢应变速率测试法,分别对比研究了核级316NG控氮奥氏体不锈钢和321奥氏体不锈钢的局部腐蚀行为,并利用扫描电子显微镜、光学显微镜等分别观察腐蚀后不锈钢的表面形貌。结果表明:316NG和321不锈钢晶间腐蚀再活化率分别为3.83%和4.47%,点腐蚀速率分别为10.74g/(m2·h)和45.97g/(m2·h),盐雾腐蚀速率分别为2.14×10-2 g/(m2·h)和12.32×10-2 g/(m2·h),应力腐蚀开裂敏感指数分别为0.078和0.10;316NG不锈钢中N和Mo元素提高了其耐局部腐蚀性能,因此其耐局部腐蚀性能均优于核电站结构材料321不锈钢的。     

绢云母和硅烷偶联剂KH550对聚氨酯/Al-Sm2O3复合涂层耐盐水性能的影响

目的提高聚氨酯(PU)/Al-Sm_2O_3复合涂层的耐盐水性能。方法以绢云母和硅烷偶联剂KH550改性PU/Al-Sm_2O_3复合涂层,系统研究改性前后涂层的微结构、红外发射率、近红外反射率及力学性能经盐水腐蚀后的变化规律,并对其成因进行分析探讨。结果经绢云母和KH550改性后的涂层与改性前的涂层相比,其微结构在腐蚀前后几乎保持不变,经盐水腐蚀相同时间时,改性涂层具有更低的1.06μm近红外反射率,更优异的力学性能。改性涂层经盐水腐蚀10 d后,其硬度、附着力和耐冲击强度仍可保持在3H、1级和50 kg×cm。结论绢云母和KH550改性可明显提高PU/Al-Sm_2O_3复合涂层的近红外低反射性能及力学性能对盐水腐蚀的稳定性。     

硬质合金的比矫顽磁力

用磁性法和 X射线衍射相分析得出了当两相 WC— Co硬质合金碳含量改变时 ,其比矫顽磁力 Hsc( A· m2 · Kg- 1)同合金碳含量 Xc、真实钴含量 XCo( wt)、WC相平均晶粒尺寸 Lwc( μm)及比饱和磁化强度 4πσ( A·m2 · kg- 1)、密度 d( Kg· m- 3)间的定量关系式Hsc+ 0 .330 4 lg L wc=7.652 - 0 .330 4 lg 1 .791 XCo1 - 1 .0 87XCo- 7.356XCo- 1 2 0 .0 Xc=0 .2 958- 0 .330 4 lg 1 .791 XCo1 - 1 .0 87XCo+ 6.488XCo- 3.2 64× 1 0 - 34 πσ=1 1 .86- 0 .330 4 lg 1 .791 XCo1 - 1 .0 87XCo+ 8.1 35XCo- 1 .0 83× 1 0 5· d- 1当合金碳含量变化时 ,溶质钨和碳在 γ相中固溶度的变化引起 γ相磁矩和 γ基体钴晶格畸变应力的改变是导致合金 Hsc值变化的主要原因。     

Effect of melting rate on microsegregation and primary MC carbides in M2 high-speed steel during electroslag remelting

Large-size primary MC carbides can significantly reduce the performance of M2 high-speed steel. To better control the morphology and size of primary MC carbides, the effect of melting rate on microsegregation and primary MC carbides of M2 steel during electroslag remelting was investigated. When the melting rate is decreased from 2 kg·min⁻¹ to 0.8 kg·min⁻¹, the columnar dendrites are gradually coarsened, and the extent of segregation of Mo and V is alleviated, while the segregation of Cr becomes severe. At 2 kg·min⁻¹, the number of primary MC carbides per unit area with the sizes in the range of 2 µm to 6 µm accounts for about 75% of all MC carbides, while the carbides are mainly concentrated on the size larger than 8 µm at 0.8 kg·min⁻¹. Thermodynamic calculations based on the Clyne-Kurz (simplified to C-K) model shows that MC carbide can be precipitated in the final solidification stage and a smaller secondary dendrite arm spacing caused by higher melting rate (2 kg·min⁻¹ in this experiment) facilitates the refinement of primary MC carbides.

     

洞庭湖湿地周围表层土壤重金属污染及其人体健康风险评价

为了查明洞庭湖湿地周围表层土壤重金属污染及其对人体健康的风险,选择2016~2018年洞庭湖区域周围10个土壤采样点,共采集了表层土壤(0~30 m)样品100份,分析了其中的重金属含量、分布,并采用地累积指数法(Igeo)、内梅罗指数法(NI)和土壤健康风险评价法等方法进行了风险评价。结果表明:土壤样品中Pb、Cd、Hg、As和Cu 5种重金属元素的平均浓度分别为53.33、1.62、0.27、26.8和37.72 mg/kg,高于研究区域土壤环境背景值。其中Cd、As的平均浓度,西洞庭湖、南洞庭湖和东洞庭湖Cd的浓度和南洞庭湖As的浓度均高于《土壤环境质量标准》(GB 15618—2018)中农用地土壤污染风险筛选值的标准。Cd、Hg、As和Cu的最大污染值在南洞庭湖,Pb的最大污染值在东洞庭湖。地累积指数法(Igeo)研究表明,三年时间里,Cd处于重度污染水平,Pb、Hg、As处于无污染到中度污染水平。内梅罗指数法(NI)研究表明,三年时间里,西洞庭湖、南洞庭湖和东洞庭湖都处于轻度污染水平。运用土壤健康风险评价体系中的无意吸食、皮肤接触、呼吸接触3种暴露因素对人体健康风险的评估表明:每百万人口中,平均有13个成年人和8个儿童具有癌症风险。研究结果为洞庭湖湿地土壤污染的来源和特征提供参考和建议。     

Immobilization of A cidithiobacillus ferrooxidans and ferric iron production

1 Introduction Acidithiobacillus ferrooxidans is a kind of Gram negative, aerobic, acidophilic and chemolitho- autotrophic bacteria which is mainly applied in bioleaching of sulphide ores for metal recovery[1]. Compared with the traditional metallurgy techniques, biohydrometallergy technology has the advantages of short process, less energy consumption, environment friendly and lower cost. Thus, biohydrometallurgy is one of the most important aspects in the process of sulphide ores. A. ferro…     

感应熔覆Ni60涂层显微组织及耐蚀性

利用两步法,感应熔覆制备了内、外壁Ni60合金涂层钢管.研究了熔覆涂层腐蚀前、后截面显微组织以及腐蚀产物膜的微观形貌特征,利用失重法测量了涂层盐雾、CO2腐蚀速率,定量评价了熔覆涂层的耐腐蚀性能.结果表明:熔覆Ni60涂层全致密,内部均匀分布大量碳化物、硼化物硬质点,涂层与基体之间冶金结合,界面处互扩散区宽度约为8 μm.熔覆Ni60涂层对基体有较好的防腐保护作用,盐雾腐蚀环境下出现锈斑的时间大于150 h,平均腐蚀速率为0.75 g/(m2· h),涂层动态CO2腐蚀相对静态CO2腐蚀更加剧烈,实验温度348 K时,静态腐蚀速率为0.78 g/(m2·h),动态腐蚀速率为1.02 g/(m2·h).     

稀土CeCl3对耐热钢Ni2Al3/Ni复合涂层抗氧化性的影响

本文采用电镀镍、低温包埋渗铝在P92铁素体耐热钢表面制备不同稀土Ce含量的Ni-Al化合物复合涂层,并对复合涂层进行650 ℃&#215;132 h的抗氧化实验。利用OM、SEM、EDS、XRD,分析涂层氧化前后的截面微观形貌,化学元素分布及物相变化规律。结果表明：涂层的氧化动力学曲线均符合抛物线规律。不含Ce的复合涂层平均氧化速率为0.4412&#215;10-6 g/cm2/s,渗铝剂中加入2%CeCl3的涂层抗氧化性明显增强,平均氧化速率为0.2957&#215;10-6 g/cm2/s,而加入过量CeCl3（4%、6%）则会在氧化过程中产生更多的孔洞,恶化了涂层的高温抗氧化性能,氧化速率相对加入2 % CeCl3的涂层有所升高。另外涂层中加入Ce元素增加了氧化膜的粘附性,对Al元素的向内扩散具有抑制作用。     

42CrMo钢在氯离子溶液中的腐蚀行为研究

目的通过研究42CrMo钻具用钢在常温下不同Cl~-浓度溶液中的腐蚀行为,为其腐蚀速率的预测奠定一定基础。方法采用浸泡实验、电化学测试技术研究42CrMo在不同浓度NaCl溶液中的平均腐蚀速率和电化学特性,并结合SEM扫描电镜对浸泡58 h后的挂片试样进行分析。结果浸泡实验分析表明,当Cl~-达到60 g/L时,42CrMo钢的腐蚀速率达到最大值,为0.124 g/(m~2·h);当Cl~-浓度继续增大时,腐蚀速率随Cl~-浓度的增加而逐渐减小。开路电位Eocp分析表明,随着Cl~-浓度的增加,Eocp总体呈现下降趋势,显示出较大的腐蚀倾向性。极化曲线分析表明,阴极极化曲线的斜率明显比阳极大,并且自腐蚀电流密度在60 g/L Cl~-溶液中达到最大值,为5.952 35μA/cm~2。腐蚀形貌研究表明,42CrMo浸泡58 h后,表面的腐蚀产物分布并不均匀,均发生了局部点蚀现象。结论随着Cl~-浓度的不断增大,42CrMo钢的平均腐蚀速率呈现先增大后减小的趋势,且在Cl~-为60 g/L时,平均腐蚀速率最大。42CrMo钢在静态常温下高Cl~-浓度溶液中以局部点蚀为主,其电化学腐蚀过程主要受阴极去氧极化的控制。     

Theoretical analysis and experimental verification of thermal decomposition mechanism of CuSe

Experiments on the thermal decomposition of CuSe were carried out by using a thermogravimetric analyzer (TGA) at different heating rates. The kinetic parameters and mechanisms were discussed based on model-free and model-based analyses. The decomposition rate and decomposition behavior of CuSe were investigated by using a vacuum thermogravimetric furnace. The results showed that the R3 model was identified as the most probable mechanism function under the present experimental conditions. The average values of activation energy and the pre-exponential factor were 12.344 J/mol and 0.152 s^-1, respectively. The actual decomposition rate of CuSe was found to be 0.0030 g/(cm²·min).     

Prediction of the Severity of Atmospheric Corrosion by Discriminant Analysis of Local Meteorological Factors

Abstract

Discriminant function analysis has been used to enable the corrosiveness of an environment to be classified into one of several broad categories, knowing the values of specified atmospheric factors. Of various combinations of meteorological factors that were tried, the following combination proved to be the most discriminating: average of daily maximum temperature in °c, average daily maximum relative humidity, number of rainy days in a month, total rainfall in mm in a month, and average pollution (SO₂ + NaCl in mg/cm² per day over a month). These criteria were used to classify stations at Delhi, Bombay and Tezpur, giving results that agreed well with those obtainedin exposure trials.     

ECAP变形对MWCNTs/AZ31复合材料抗腐蚀性能的影响

采用碳纳米管孕育块铸造法制备多壁碳纳米管/AZ31镁基复合材料,经等径角挤压(ECAP)变形后对复合材料在3.5%NaCl(质量分数)的腐蚀介质中进行静态浸渍试验和电化学极化曲线测定,研究等径角挤压变形工艺对复合材料抗腐蚀性能的影响;利用数码相机、扫描电子显微镜对复合材料腐蚀前后的表面形貌进行观察和分析;并对复合材料的抗腐蚀机理进行分析。结果表明:等径角挤压变形工艺能有效的提高多壁碳纳米管(CNTs)/AZ31复合材料的抗腐蚀性能,经等径角挤压变形4道次后,复合材料的平均腐蚀速率由挤压态的0.6035mg/(m2·s)降为0.2963mg/(m2·s)。腐蚀电流密度Icorr由ECAP变形前的3.363μA/cm2减小到2.269μA/cm2。     

Electroplating on Aluminium

Coatings containing tin and cadmium, produced either as a layered electrodeposit of the two metals or by electrodepositing alloys from sulphate or fluosilicate baths, have been subjected to corrosion tests in comparison with other coatings.

Coatings of tin-cadmium alloy or of cadmium deposited over an equal thickness of tin have been found to have outstanding durability in laboratory salt-spray tests and, in all environments, are as well able as cadmium coatings to prevent rusting at pores when freshly exposed to corrosion. The alloy coatings have an advantage over cadmium in that they are less affected by the organic vapours emitted by some insulating materials. It has also been shown, by other investigators, that the alloy coatings have useful anti-galling properties.

Protection of steel exposed to the weather by the sea has lasted longer for some alloy coatings than it has for cadmium coatings of the same thickness, but it is doubtful whether this superiority can be obtained consistently. Compared with cadmium coatings, alloy coatings were no better in continuous or intermittent immersion in the sea and were inferior in exposure to inland urban atmospheres.

A tin undercoating 0·05mil? thick improved the performance of zinc coatings on flat plates in a marine atmosphere, but such an undercoating had no appreciable effect on the life of cadmium coatings in any type of exposure or of zinc coatings exposed inland.     

Magnetocaloric effect of nonstoichiometric La1−xFe11.4+xSi1.6 alloys with first-order and second-order magnetic transitions

Variation from a first-order magnetoelastic transition (FOMT) to a second-order magnetic transition (SOMT) could be controlled by finely adjusting the Fe/La ratio in the non-stoichiometric La_1−xFe_11.4+xSi_1.6 (x = 0, 0.05, 0.10, 0.15 and 0.20) alloys. Particularly, a nearly stoichiometric ratio of NaZn₁₃-type phase was obtained with an addition of excess 0.15 at% Fe. When x value increased from 0 to 0.20, the Curie temperature (T_C) increased from 198.6 to 216.6 K due to lattice shrinkage and the magnetic entropy change (−ΔS_M) decreased from 18.4 to 8.0 J/(kg·K) (at 0−2 T) and from 22.5 to 13.8 J/(kg·K) (at 0−5 T), which may be ascribed to the change from the itinerant-electron metamagnetism (IEM) to second order magnetic transition. Thus their effective refrigeration capacities declined from 347.6 to 245.9 J kg⁻¹ under 0–5 T, which values were comparable to the Gd₅Si₂Ge_1.9Fe_0.1. The Fe/La ratio in NaZn₁₃-phase was possibly dominant to induce the transition from first to second order among La_1−xFe_11.4+xSi_1.6 alloys. The thermal hysteresis decreased by 87% to 0.3 K and magnetic hysteresis losses reduced by 90% to 1.4 J kg⁻¹ under 0–5 T. Near the transition border, the alloys with x = 0.15 produced a giant magnetocaloric effect of about 11.8 J/(kg·K) under 0–2 T at T_C = 205.6 K. The magnetic hysteresis was 3.01 J kg⁻¹ and the thermal hysteresis was 1.9 K. The material near the border of transition could be suitable for future magnetic refrigeration application.     

纯铝1060在中国南沙群岛严酷海洋大气中的腐蚀以及点蚀行为

通过质量损失测量、扫描电子显微术、能谱分析、X射线光电子能谱和电化学阻抗谱等技术研究纯铝1060在南沙群岛海洋大气环境中暴露34个月后的腐蚀行为以及点蚀行为.结果表明,在纯铝表面发生严重的点蚀,并且暴露13个月后的平均腐蚀速率达到1.28 g/(m2·a).X射线光电子能谱的测试结果表明主要的腐蚀产物为Al2O3、Al...