五倍子对釉质抗酸蚀作用的实验研究

目的:观察中药五倍子对釉质抗酸蚀作用的效果。方法:采用500 g/L五倍子水浸剂为实验组,去离子水为阴性对照,20 g/L氟化钠为阳性对照,对60个正常离体牙釉质表面进行处理,制备人工龋模型,用硬组织切片机制备100μm原切片,通过显微放射照射系统观察测量五倍子对釉质的抗酸蚀作用效果。结果:500 g/L五倍子水浸剂组较去离子水对照组脱矿少(P<0.05),与20 g/L氟化钠对照组相比无显著差异(P>0.05)。结论:500 g/L五倍子水浸剂可明显增强釉质抗酸蚀能力,其效果与20 g/L氟化钠相当。

绿茶提取物EGCG对牙本质抗酸蚀作用的初步研究

目的观察绿茶提取物表没食子儿茶素没食子酸酯(EGCG)对牙本质抗酸蚀作用的影响。方法选取酸蚀症志愿者40名,随机分成2组。制作个别托盘,对照组托盘内注入羧甲基纤维素凝胶(CMC),实验组注入添加了EGCG的CMC凝胶,于夜间睡时佩戴,清晨取下。实验当天及第4周收集培养液,用放射免疫试剂盒测量Ⅰ型胶原羧基端肽(ICTP)的含量。结果凝胶种类对ICTP的含量均有影响,EGCG能有效降低ICTP的表达水平(P<0.05)。结论 EGCG能有效减少脱矿牙本质胶原的降解,提高牙本质抗酸蚀的能力。

英国高氏碱溶性抗酸蚀剂SP2112在生产中常见故障及对策

在种类繁多的丝网印刷抗蚀剂中,碱溶性抗蚀剂用途最广。英国高氏生产的碱溶性抗蚀剂—SP2112对氯化铜及其他常用的腐蚀剂具有特别良好的耐蚀性能,易被氢氧化钠稀溶液或碳酸钠喷液除去,但强碱液则只能将抗蚀剂软化,可另外用水洗法除去。这样。

硫化氢与硫酸腐蚀油井水泥石的对比

采用G级油井水泥净浆,从腐蚀前后水泥石抗压强度、水化产物中氢氧化钙含量、SEM微观结构特征和孔隙结构的变化等方面,进行了硫酸溶液和硫化氢对水泥石的腐蚀对比实验。结果表明,设计的常温常压的硫酸溶液腐蚀实验与标准的高温高压腐蚀实验有较好的相关性和可比性,而且硫酸溶液腐蚀实验能够更直观地反映出水泥石潜在的腐蚀因素。利用常温常压的硫酸溶液腐蚀实验能够作为油井水泥石腐蚀研究的前期实验和油井水泥石抗酸蚀的耐久性实验,对降低水泥石腐蚀实验成本和风险,提高实验效率,更好地开展油井水泥石完整性研究有重要的应用价值。

表面活性剂加氟化钠涂料对牙骨质表面显微硬度的体外研究

目的 :探讨表面活性剂加氟化钠涂料防治根面龋是否优于单独用氟化钠涂料或洗必泰涂料。方法 :在离体牙釉 -牙骨质界下开窗 4mm× 4mm ,分别经洗必泰加氟化钠涂料 (简称氟泰涂料 )、洗必泰涂料、氟化钠涂料等处理后进行矿化实验和抗龋实验 ,然后测定各组牙骨质表面的显微硬度。结果 :3组矿化实验前、后牙骨质表面硬度相比 ,氟泰涂料组和氟化钠涂料组较洗必泰组均有显著差异 ,且氟泰组比氟化钠组硬度值显著增加。抗龋实验前、后牙骨质表面显微硬度值相比 ,氟泰组、氟化钠组无显著差异 ,洗必泰组、对照组均有显著差异。结论 :用氟泰涂料改善牙骨质表面硬度与氟化钠组具相同效果 ,且优于氟化钠组。

氟离子透入对中学生防龋作用的卫生学评价

氟离子透入防龋是近几年来一项新的防龋技术,其原理是增强牙齿的矿化,形成抗酸蚀能力较强的氟磷酸钙保护层,从而起到防龋作用。我科于1989年初至1991年初选择了和平街一中、二中初一、初二的学生644人为观察对象,一中为试验组365人,二中为对照组279人,进行了2年6次氟离子透入。观察期间共检查学生龋齿3次。(1)防治前试验组患龋率50.6%(185/365),对照组患龋率52.3%(146/279),差异不显著(P】0.05)。(2)实行氟离子透入1年后试验组患龋率51.5%(188/365),对照组患龋率60.2%(168/279),有显著性差异(P【0.05)。

无粉红圈黑化工艺研究——美国电化学公司MARK E.EONTA TIANREN CHEN来华报告

引言 随着印制板技术的发展,印制板的层数愈来愈多,线路愈来愈细,孔径愈来愈小,因此,对多层板黑化处理的要求也愈来愈高。一方面要求铜箔经处理后提高与半固化片的结合能力,另一方面要求处理后的氧化层加强抗腐蚀性能。继续采用原有的典型的黑化工艺,出现粉红圈的可能性将愈来愈大。所谓粉红圈是指通过孔壁与内层孔环的交界处,其孔环铜面的氧化膜已经变色,或由于化学反应而被除去露出铜的本色(粉红色)的现象。粉红圈往往在印制板制作后期才被发现。

Comparison of corrosion resistance of MgAl-LDH and ZnAl-LDH films intercalated with organic anions ASP on AZ31 Mg alloys

The aspartic acid(ASP),an environment-friendly corrosion inhibitor,was explored to intercalate into the ZnAl-layered double hydroxide(ZnAl-LDH)and MgAl-LDH coatings on AZ31 magnesium alloys by a facile one-step hydrothermal method.The morphology,composition,structure and corrosion resistance of the prepared coatings were comparatively investigated.It is found that the uniform and dense layered nanosheet(NS)vertically grows on the substrate,and the MgAl−ASP-LDH films exhibit a three-dimensional(3D)rose-like sheet structure with high ratio of pore coverage.The MgAl−ASP-LDH coating exhibits better corrosion resistance and durability of longtime immersion than ZnAl−ASP-LDH coating.The corrosion current density of two coatings is two or three orders of magnitude lower than that of bare Mg alloy,indicating that ZnAl/MgAl-LDH films intercalated with organic ASP anions can significantly improve the corrosion resistance of Mg alloy.

Enhanced corrosion resistance of phytic acid coated magnesium by stearic acid treatment

A green chemical conversion coating for magnesium was obtained with a phytic acid solution. The microstructure and corrosion properties of phytic acid conversion coated magnesium were further improved by soaking in stearic acid solution. The phytic acid conversion coated magnesium after soaking in the stearic acid showed no micro-cracks and the surface became very smooth. The corrosion behavior of the uncoated and coated magnesium samples was studied by electrochemical methods. The corrosion resistance of the stearic acid treated sample was much higher than that of phytic acid conversion coated magnesium or uncoated magnesium. The electrochemical results indicated that the stearic acid treated coating provided effective corrosion protection to the magnesium sample.

Properties of Belite-Rich Portland Cement and Concrete in China

Performances of belite-rich Portland cement, or HBC （high belite cement）, and the resultant concrete are introduced by comparing with that of alite based PC （Portland cement） and concrete. The comparison study of cement properties indicates that HBC possesses the properties of less water demand for normal consistency, better compatibility with water reducer, higher later age strength after 28-day under standard curing temperature of 20 ℃, unique strength gain under elevated curing temperatures of 38-70 ℃, lower hydration heat evolution and temperature rise, lower drying shrinkage and excellent resistance to sulphate attack. These results have been demonstrated by the comparison performance evaluation of concretes prepared by HBC and PC in terms of workability, physical mechanical properties and durability when making high performance high strength concrete and massive concrete.

The compressive strength experimental study of cemented soil under H2SO4 corrosive in earlier period

In order to simulate and study the erosion effect process such as the changes of corrosive depth and unconfined compression strength of cemented soil sample in earlier period from 0 day to 60 days, a series of tests including unconfined compressive tests, measuring the blocks＇ sizes, and taking photos, are conducted on the cemented soil blocks which were cured in different concentrations of H2SO4 solutions. The results of tests show that the corrosive depth is increasing and the unconfined compression strength is decreasing with the increase of H2SO4 solution concentration at the same erosion time, and the corrosive degree is increasing with the corrosive time. In the earlier state, the corrosive effect is serious, but the effect becomes slow in the later state in the same concentrated H2SO4 solution. After take statistics the date, a coefficient a is put forward to predict the reduction of the compressive strength of cemented soil in various concentration of H2SO4 solution, which could be used in practical design.

废液焚烧炉耐火材料长周期使用探讨

废液焚烧炉焚烧POSM装置产生高污染碱性废液水和酸性废水,但焚烧炉耐火砖制约焚烧炉能否长周期运行的关键因素。因此,需要一种耐火砖在1 100 ℃以上的高温情况下既能耐受碱性废水的侵蚀又要耐受酸性废水的侵蚀,从而达到耐火砖能够长周期使用的目的。文章基于此进行探讨。

表面活性剂与氟化钠涂料对牙骨质表面显微硬度的体外研究

目的 观察表面活性剂与氟化钠涂料防治根面龋与单独用氟化钠涂料或洗必泰涂料防龋效果的比较。方法 测定离体牙釉 -牙骨质界下 4× 4mm开窗区分别经洗必泰与氟化钠涂料 (简称氟泰涂料 )、洗必泰涂料、氟化钠涂料等处理 ,观察进行矿化试验和抗龋试验后牙骨质表面的显微硬度。结果 试验前后牙骨质表面硬度相比 ,氟泰涂料组、氟化钠涂料组均有显著差异 ,且氟泰组比氟化钠组硬度值显著增加。抗龋试验前后牙骨质表面显微硬度值相比 ,氟泰组、氟化钠组无显著差异。洗必泰组及对照组均有显著差异。结论 用氟泰涂料可增强牙骨质表面硬度 ,与氟化钠组效果相同 。