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1.
Electrochemical copolymerization of phenol and aniline was achieved on 304 stainless steel anodes in neutral water solution with an electrolyte of Na2SO4O4. Compared with pit corro-sion potential of different copolymer coatings, the best solution composition was 0.09 mol/L phenol and 0.01 mol/L aniline. Through infrared spectrum analysis, polyaniline structure was proved in phenol-aniline copolymer, as well as more side chains. Scanning electron mi-croscope was used to analyze microstructure of copolymer coating, taking advantage of part solubility of phenol-aniline copolymer in tetrahydrofuran, the bifurcate network structure was observed. The copolymer coating microstructure was summarized, compared with the performance of polyphenol coatings, the reasons of corrosion resistance enhancement with the addition of aniline in electropolymerization reaction was assumed as well. 相似文献
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Bibhuti Bhusan Champati Bhuban Mohan Padhiari Asit Ray Tarun Halder Sudipta Jena Ambika Sahoo Basudeba Kar Pradeep Kumar Kamila Pratap Chandra Panda Biswajit Ghosh Sanghamitra Nayak 《Molecules (Basel, Switzerland)》2022,27(9)
Andrographolide, the principal secondary metabolite of Andrographis paniculata, displays a wide spectrum of medicinal activities. The content of andrographolide varies significantly in the species collected from different geographical regions. Therefore, this study aims at investigating the role of different abiotic factors and selecting suitable sites for the cultivation of A. paniculata with high andrographolide content using a multilayer perceptron artificial neural network (MLP-ANN) approach. A total of 150 accessions of A. paniculata collected from different regions of Odisha and West Bengal in eastern India showed a variation in andrographolide content in the range of 0.28–5.45% on a dry weight basis. The MLP-ANN was trained using climatic factors and soil nutrients as the input layer and the andrographolide content as the output layer. The best topological ANN architecture, consisting of 14 input neurons, 12 hidden neurons, and 1 output neuron, could predict the andrographolide content with 90% accuracy. The developed ANN model showed good predictive performance with a correlation coefficient (R2) of 0.9716 and a root-mean-square error (RMSE) of 0.18. The global sensitivity analysis revealed nitrogen followed by phosphorus and potassium as the predominant input variables influencing the andrographolide content. The andrographolide content could be increased from 3.38% to 4.90% by optimizing these sensitive factors. The result showed that the ANN approach is reliable for the prediction of suitable sites for the optimum andrographolide yield in A. paniculata. 相似文献
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Elza Sundhani Agung Endro Nugroho Arief Nurrochmad Ika Puspitasari Dita Amalia Prihati Endang Lukitaningsih 《Molecules (Basel, Switzerland)》2022,27(20)
Co-administered medicinal herbs can modify a drug’s pharmacokinetics (PK), effectiveness, and toxicity. Andrographis paniculata (Burm. f.) ethanolic extract (APE) and andrographolide (AND) (a potent CYP2C9 inducer/inhibitor) can alter the pharmacokinetic parameters of glipizide (GLZ). This study aimed to determine the potential pharmacokinetics of herb–drug interactions between GLZ and APE/AND in the plasma of normal and diabetic rats using the HPLC bioanalysis method. The glipizide bioanalytical method established with RP-HPLC/UV instrument was validated following the EMA guidelines. GLZ was administered alone and in combination with APE or AND to normal and diabetic rats. The GLZ pharmacokinetic parameters were estimated according to the correlation between concentration and sampling time using the PK solver program. A simple and rapid GLZ bioanalysis technique with a lower limit of quantitation of 25 ng/mL was developed and presented the following parameters: accuracy (error ≤ 15%), precision (CV ≤ 15%), selectivity, stability, and linearity (R2 = 0.998) at concentrations ranging 25–1500 ng/mL. APE administration significantly improved the Cmax and AUC0–t/AUC0–∞ GLZ values in normal and diabetic rats (p < 0.05). AND significantly reduced the bioavailability of GLZ in diabetic rats with small values of T 1/2, Cmax, and AUC0–t/AUC0–∞ (p < 0.05). This combination can be considered in administering medications because it can influence the pharmacological effects of GLZ. 相似文献
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M. Menning C. Schelle A. Duran J.J. Damborena M. Guglielmi G. Brusatin 《Journal of Sol-Gel Science and Technology》1998,13(1-3):717-722
Glass-like sol-gel coatings have been investigated as corrosion protective coatings on stainless steel. Magnesium- and borosilicate coatings with thickness of about 100–700 nm and methyl-modified SiO2 coatings with a thickness of about 2 m were deposited on stainless steel plates by dip-coating. The coatings were densified between 400°C and 500°C in different atmospheres (N2, air) for 1 h. The corrosion protection against gaseous attack was investigated by accelerated corrosion tests, at 800°C in air for 1 h. A corrosion protection factor was calculated from the relation Fe/Fe2O3, determined by XRD on the surface of coated and uncoated samples. Methyl-modified SiO2 coatings showed a protection factor, which was 2 orders of magnitude higher than for the other coatings. Electrochemical investigations were performed on samples submerged in a NaCl solution for 200 h. The corrosion propagation, polarization resistance and impedance vector were measured. For accelerated corrosion tests, polarization intensity curves were determined for high potentials of up to 1 V. Again excellent results were obtained for the methyl-modified SiO2 coatings, which remained passive for 200 h. Results of the salt spray corrosion test, however, showed no corrosion protection by the sol-gel coatings. After 2000 h in the salt spray chamber the steel was corroded and the coatings peeled off. It is concluded that for the further development of these coatings an improved interfacial passivation will be required. 相似文献
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18/8型不锈钢在受力形变条件下腐蚀电化学行为的研究 总被引:5,自引:0,他引:5
应用电化学稳态技术、电化交流阻、抗微区电化学技术及扫描电等方法,研究18/8型不锈钢在Na2S2O3稀溶液中,受外力形变条件下,的腐蚀电化学行为,结果表明,力学因素可使表面腐蚀电化学活性增加,表面微裂纹的发生、消失和再钝化的动态过程,同时受电位和拉应力的影响;点腐蚀可优先发生在应力集中位置,点蚀的发展可能诱导不锈钢的应力腐蚀开裂。 相似文献
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Al2O3 coatings were obtained by the alkoxide route and deposited on stainless steel using the dip coating technique. The starting precursor was aluminum sec-butoxide modified by acrylic acid in order to prevent its precipitation in the presence of water.Useful information for the structural organization of alumina coatings on stainless steel is deduced from SIMS analysis. SIMS data reveal that the coating structure brings into play two different layers: an outer alumina layer that is more or less doped, mainly by iron, and an internal layer corresponding to the alumina/steel interphase. Beneath the interphase, the presence of an oxidized steel layer on the substrate surface is detected.Whatever the coating, the alumina/steel interphase exhibits a nearly constant thickness. On the other hand, a thickness variation of the oxidized steel layer is observed between samples under study: this thickness increases with the curing time of the coating. 相似文献
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《Journal of separation science》2018,41(16):3232-3240
In this work, high‐performance liquid chromatography with diode array detection was applied for the simultaneous determination of andrographolide and dehydroandrographolide in Andrographis paniculata and its preparations. As a result of the incomplete baseline separation caused by complex backgrounds, the classical univariate calibration method failed to determine accurate contents of the analytes. On this occasion, chemometric second‐order calibration based on the well‐known alternating trilinear decomposition algorithm was then explored to serve as a post‐experimental remedial tool to solve this problem. By using the intelligent “mathematical separation” of alternating trilinear decomposition, the peak areas of the analytes do not need to be directly measured and the predictive results become accurate. The contents of andrographolide and dehydroandrographolide were determined to be (7.95 ± 0.15) and (1.85 ± 0.02) μg/mL for Andrographis paniculata, (1.34 ± 0.01) and (5.53 ± 0.04) μg/mL for its preparations, which was in agreement with those obtained by a reference liquid chromatography with mass spectrometry method. This study showed the superiority of second‐order calibration method over classical univariate calibration method for simultaneous determination of multi‐analytes in complex samples. It also proved that second‐order calibration may be a good choice for remedying incomplete baseline separation problem, with the accompanied reduction of experimental burden and toxic organic solvents as well as analysis time and cost. 相似文献
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采用阳极氧化技术在不锈钢丝网上成功地自生长了结构致密的氧化物膜,并以此为载体,通过电化学沉积工艺制备了Cu/不锈钢丝网催化剂。以甲苯、丙酮、乙酸乙酯及二氯甲烷为模型反应,考察了4种不同种类挥发性有机化合物(VOCs)在该催化剂上的完全氧化活性。结果表明电化学沉积时间为15 min制备得到的催化剂上完全氧化丙酮、甲苯、乙酸乙酯及二氯甲烷的温度分别为240、220、260和440℃。在220℃反应条件下进行60 h的甲苯氧化稳定性试验结果显示该催化剂催化氧化甲苯的转化率一直保持98%以上,表现出较好的稳定性。扫描电镜,X射线衍射及X射线光电子能谱等表征结果表明,不锈钢丝网载体表面的阳极氧化物膜有利于提高活性组分的分散度。设计采用电沉积工艺大大提高了催化剂表面活性物种与载体的结合牢固度。 相似文献
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Ithasbeenwidelyacceptedthatelectrochemicalcorrosionreactionsareinvolvedinthe.stresscorrosioncrackingprocessesofmostmetaljaqueoussolutionsystems'.Accordingtothecharacteristicsofdynamicstrainatthecracktipofmetal,itisofgreatimportancetostudytheinfluenceofvariedpotentialsonthedynamicstrainprocessatcracktipbydifferentpotentialpertllrbationsbetweenanodicandcathodicpotCntials.SmoothcylindricaltensilespecimenwasusedinSSRT(strainrate4.l6x's-').Allexperimentswereperformedino.75molILHCl O.25molILNa… 相似文献
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基于电化学噪声技术建立了不锈钢海洋大气点蚀监测系统,利用该系统对处于干湿循环环境下不锈钢的点蚀行为进行监测. 使用时域谱图、时域统计、频域谱图和散粒噪声理论等分析方法对采集到的电化学噪声数据进行处理分析,并结合动电位极化法,形貌分析法共同研究不锈钢的点蚀行为. 研究结果表明,304不锈钢在模拟海洋大气环境下的点蚀行为分为钝化、亚稳态点蚀和稳态点蚀三个阶段. 在钝化阶段,电位电流噪声信号出现少量的同步异向波动,腐蚀事件发生频率高,平均电量低;在亚稳态点蚀阶段,电位电流噪声信号出现大量的同步同向波动,腐蚀事件发生频率降低,平均电量上升,通过扫描电镜观察蚀点;在稳态点蚀阶段,电位电流噪声信号不仅存在大量的同步同向波动,还出现了同步异向波动,腐蚀事件发生频率较低,平均电量大幅度上升,通过扫描电镜观察到电极表面出现小而浅的蚀点. 而动电位极化法可以证实304不锈钢点蚀的发生. 两种分析方法所得结果具有较好的一致性,证明该监测系统很好地实现了对模拟海洋大气环境下304不锈钢点蚀行为的连续监测,并能判断点蚀的发生. 相似文献
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Synthesis and Properties of Cerium and Titanium Oxide Thin Coatings for Corrosion Protection of 304 Stainless Steel 总被引:1,自引:0,他引:1
A. Nazeri P.P. Trzaskoma-Paulette D. Bauer 《Journal of Sol-Gel Science and Technology》1997,10(3):317-331
Powders and thin coatings of ceria and titania were synthesized from aqueous and solvent-based precursors. Thin coatings were deposited on polished 304 stainless steel coupons by dipping them in the appropriate sol-gel oxide precursors. The coatings were subsequently densified and crystallized at several hundreds of degrees. It was possible to obtain dense titania coatings by applying thin coatings of cerium dioxide prior to titania on stainless steel substrates. Underlayer ceria coatings proved to be pivotal in obtaining dense titania coatings and preserving the integrity of the stainless steel while going through the high temperature treatments. The effect of processing parameters such as the atmosphere of heat-treatment, and temperature on the microstructure and crystal structure of the films and powders of ceria and titania was investigated. X-ray diffraction was used to identify the crystal structure of films and powders upon heat-treatment. Electrochemical measurements in NaCl, and analytical techniques such as SEM and EDX were used to evaluate the corrosion performance and pitting morphology of coated samples. A composite coating of ceria and titania was able to prevent crevice corrosion and increase the pitting resistance of the 304 stainless steel relative to the uncoated substrate. 相似文献
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用表面增强拉曼光谱研究BMAT对不锈钢的缓蚀机理 总被引:1,自引:0,他引:1
应用表面增强拉曼散射光谱(SERS)技术,研究0.5%HCl体系中缓蚀剂在18-8不锈钢表面的吸附。谱图是在不锈钢表面电沉积不连续Ag颗粒条件下测得的。缓蚀剂BMAT通过电极表面与缓蚀剂中的N原子,以及苯并咪唑环的共轭大π键形成化学吸附,BMAT斜卧于电极表面。其烯丙基起到空间的阻碍的作用。 相似文献
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HaoWANG QiuHongLI SuXiangWU FengHuaWEI 《中国化学快报》2004,15(4):486-488
Polyaniline(PANI)film was electrosynthesized on 304 stainless steel by cyclic voltammetry using aqueous oxalic acid as supporting electrolyte.The potential sweep rates were changed to achieve the PANI film with different thickness and structures.Protective properties of the PANI film for corrosion of stainless steel in 3% NaC1 aqueous solution were investigated by monitoring potentiodynamic polarization curves and electrochemical impedance spectroscopy(EIS).The results showed that the PANI film which was formed with lower sweep rate led to more positive shift of corrosion potential and greater charge transfer resistance,reflecting higher inhibition for corrosion of the stainless steel. 相似文献
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新型十二烷基三甲氧基硅烷/氧化石墨烯复合膜对430不锈钢耐蚀性能的影响 总被引:1,自引:0,他引:1
使用一步电沉积法在430不锈钢上制备出十二烷基三甲氧基硅烷(DTES)/氧化石墨烯(GO)复合膜。 拉曼光谱(Raman)与扫描电子显微镜(SEM)测试表明,氧化石墨烯均匀地混合在硅烷膜中,并用电化学交流阻抗与极化曲线方法对这种复合膜所保护的430不锈钢进行耐蚀性能测试。 结果显示,在3.5%NaCl溶液中,430不锈钢会发生腐蚀反应,而存在硅烷复合膜的430不锈钢的耐蚀性能显著地提高。 研究表明,由于氧化石墨烯出色的阻隔性能一定程度上弥补了硅烷膜的缺陷,而且延长了腐蚀介质通过硅烷基质的路径,因此复合膜有着对基底物质更强的保护性能。 相似文献
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《Journal of separation science》2017,40(24):4865-4871
A novel isolation strategy, online hyphenation of ultrasonic extraction, Sephadex LH‐20 column chromatography combined with high‐speed countercurrent chromatography, was developed for pure compounds extraction and purification. Andrographolide from Andrographis paniculata was achieved only in a single step purification protocol via the present strategy. The crude powder was ultrasonic extracted and extraction was pumped into Sephadex LH‐20 column directly to cut the nontarget fractions followed by the second‐dimensional high‐speed countercurrent chromatography, hyphenated by a six‐port valve equipped at the post‐end of Sephadex LH‐20 column, for the final purification. The results yielded andrographolide with the amount of 1.02 mg and a purity of 98.5% in a single step, indicating that the present method is effective to harvest target compound from medicinal plant. 相似文献
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用由阴离子交换膜隔开的三室电解池作为采样器,电解法采集1Cr18Ni9Ti不锈钢样品,并测定其中固溶钛的含量。测定结果和酸溶样法的一致。文中讨论了采样原理、采集质量的确定方法,电解质及电解电流的选择。 相似文献
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胶束毛细管电泳在线扫集技术同时分离测定穿心莲内酯和脱水穿心莲内酯的研究 总被引:1,自引:0,他引:1
采用胶束毛细管电泳在线扫集技术分离测定了中药穿心莲中脱水穿心莲内酯和穿心莲内酯.电泳条件:以20 mmol/L H3BO310 mmol/L NaH2PO4-50mmol/L SDS(含体积分数20%甲醇,pH 2.4)为电泳运行缓冲溶液,未涂层石英毛细管(58 cm×50 μm i.d.,有效长度为41.2 cm)为分离通道,重力进样,进样高度为11 cm,-20 kV恒压,检测波长为246 nm.富集倍数可以达到200倍以上.在5.70~91.20 mg/L,和3.96~31.68 mg/L范围内呈良好的线性关系,对两种内酯分别进行了定量分析.加标平均回收率脱水穿心莲内酯为100.80%,穿心莲内酯为98.06%. 相似文献