Protection of iron corrosion by stearic acid and stearic imidazoline self-assembled monolayers

A type of stearic imidazoline (IM) inhibitor was prepared using stearic acid (SA) and diethylenetriamine (DETA) as raw materials. The monolayers of IM and SA were assembled on the iron surface. The electrochemical characterization of stearic acid (SA) and stearic imidazoline (IM) on an oxide free iron surface had been studied. The monolayers of IM inhibitor were characterized by electrochemical impedance spectroscopy (EIS), electrochemical polarization curves, double layer capacitance, X-ray photoelectron spectroscopy (XPS) and molecular simulation. The results of electrochemical studies had illustrated that the inhibition efficiency of IM was higher than SA. XPS showed that the IM molecules adsorbed on the iron surface. The molecular simulation calculations showed that the IM molecules were tilted at an angle on the iron surface.     

Effect of Artabotrys odoratissimus extract as an environmentally sustainable inhibitor for mild steel corrosion in 0.5 M H2SO4 media

Artabotrys odoratissimus inhibitory effect on mild steel (MS) corrosion in 0.5 M H₂SO₄ solution has been assessed utilizing mass loss, electrochemical potentiodynamic polarization, and impedance spectroscopy techniques. The Artabotrys odoratissimus plant has a wide range of bioactive compounds. Phytochemicals were tested for ethanolic Artabotrys odoratissimus leaves extract (AOLE) using the FeCl₃ test, Salkowaski's test, and others. Corrosion tests were conducted at varying inhibitor concentrations and temperatures. The inhibitory impact of AOLE on corrosion of MS was reported to improve with increasing concentration. Polarization experiments revealed that AOLE is a mixed kind of inhibitor and the inhibition efficacy (η_w) for MS is 93.27% for 1.25 g/L AOLE. For Electrochemical impedance spectroscopy (EIS), maximal inhibitory efficacy (η_w) was 91.62% due to AOLE adsorption on the MS surface. The obtained results using each methodology are highly consistent and closely resemble each other. The adsorption of AOLE molecules on an MS surface from the bulk of the solution causes the inhibitor's inhibition action, and the adsorption mechanism follows Langmuir adsorption isotherm. The computed $\Delta G_{ads}^o$ values ranged between ?32.919 and ?33.520 kJ mol^?1, implying a spontaneous and exothermic inhibitory action. The thermodynamic and activation parameters are often used to understand corrosion inhibition mechanisms. The comparison of corrosion product and pure extract FT-IR spectrum indicates the nature of AOLE adsorption on the MS surface. The surface morphology of MS samples was assessed using atomic force microscopy (AFM), scanning electron microscope (SEM), and contact angle techniques.     

Improved Experimental Procedure for the Synthesis of the Potent MEK Inhibitor PD184352

An improved synthesis of the potent MEK inhibitor PD184352 (2-(2-Chloro-4-iodo-phenylamino)-N-cyclopropylmethoxy-3,4-difluoro-benzamide)) is herein reported. This new and reproducible protocol provides a simple and efficient way of generating gram quantities of PD184352 with minimal purification.     

Corrosion inhibition of zinc in aqueous acidic media using a novel synthesized Schiff base – an experimental and theoretical study

Abstract

The kinetics of H₂ production during Zn corrosion in 0.5?M HCl without and with various additives of N,N'-bis-(1-hydroxyphenylimine)-2,5-thiophenedicarboxaldehyde (HPTD) was studied using gasometry and electrochemical techniques. The surface of the corroded Zn samples was investigated using SEM and Optical Profilometry. The rate of H₂ production (RHP) increased with the immersion time and temperature. Presence of HPTD mitigated RHP due to an adsorption process. The electrochemical impedance spectroscopy showed that HPTD had a good inhibitive effect. Polarization data proved that HPTD acted as a surface-active mixed-type inhibitor. Some thermodynamic parameters were deduced and discussed. Theoretical calculations were also conducted to corroborate the capability of HPTD to protect Zn surface from corrosion process.     

人类谷胱甘肽硫转移酶家族等位基因蛋白B与抑制剂作用模型的理论研究

采用分子动力学模拟方法系统地研究了谷胱甘肽硫转移酶家族(Glutathione S-transferases,GSTs)的等位基因蛋白B(GSTP1*B)与抑制剂利尿酸(EA)以及EA的谷胱甘肽(GSH)共轭物EAG(I),EAG(O)的具体结合方式.抑制剂及其谷胱甘肽共轭物与蛋白的相互作用能计算结果及分子动力学轨迹的统计分析结果表明,GSTP1*B与EA的谷胱甘肽共轭物的结合能力优于其与EA的结合能力,Phe8,Arg13,Trp38和Tyr108是作用过程中的关键残基,对稳定抑制剂及其谷胱甘肽共轭物在GSTP1*B的G和H位点的构象具有重要的作用.通过对构象的统计分析发现,残基Phe8和Tyr108与GSTP1*B酶对抑制剂的选择性密切相关.     

High Sensitive Electrochemiluminescence Biosensor Based on Ru(phen)32+-loaded Double Strand DNA as Signal Tags use to Detect DNA Methyltransferase Activity

DNA methyltransferase (DNA MTase) can act as biomarker for many diseases and it is important to develop some new methods for sensitive detection of DNA MTase. In this work, a highly efficient electrochemiluminescence (ECL) sensor had been designed for detection of DNA MTase based on Ru(phen)₃²⁺ loaded double strand DNA (dsDNA- Ru(phen)₃²⁺) as signal tags. Ru(phen)₃²⁺ had been efficiently embed in the dsDNA produced through a simple hybridization chain reaction. First, a hairpin probe was designed, which can be specifically recognized by Dam MTase and modified with -SH at one end. It was modified on the surface of gold electrode by -SH as an immobilization probe (IP). This IP will be methylated in the present of Dam MTase and digested by DpnI following. Results in the release of capture probe (CP) which remains on the surface of gold electrode. The CP can hybridize with the single stand part of the dsDNA- Ru(phen)₃²⁺ and make the immobilization of ECL tags on the electrode surface, which results in a strong ECL signals detected. However, without the effect of Dam MTase, the hairpin structure of IP remains stable and cannot capture signal tags, and can only detecte weak ECL signals. The biosensor can detect the activity of Dam MTase in the concentration range of 0.01 U/mL to 20 U/mL with the ECL intensity and the logarithm of the concentration have a linear relationship, and the detection limit is calculated to be 7.6 mU/mL. The developed sensor has the ability to specifically detect Dam MTase, which can be differentiated from other types of DNA MTase. In addition, the designed method has good applicability to detect Dam MTase activity in serum samples and been applied to detect its inhibitor with high efficiency.     

高通量虚拟筛选CDK2/Cyclin A2靶点抑制剂

CDK2/Cyclin A2复合蛋白的异常表达与乳腺癌、 口腔癌、 食管鳞状细胞癌的发生密切相关. CDK2/ Cyclin A2复合蛋白的活性位点不同于CDK2单体. 至今临床上尚无靶向此复合蛋白的药物分子. 针对CDK2/Cyclin A2复合蛋白, 以实验报道的10个抑制剂分子构建药效团模型, 通过药物体外药代动力学（ADME）、 Docking、 聚类分析、 毒性预测, 从DrugBank, ChEMBL和TCM@Taiwan 3个数据库约90万组数据中进行高通量虚拟筛选, 进一步进行MD模拟、 MM/PBSA结合自由能计算、 能量分解和平均非共价作用(aNCI)分析, 筛选出3个抑制效果优于阳性实验药Roscovitine的先导分子: DrugBank-2004, DrugBank-583和ChEMBL-7122. 与CDK2蛋白相比, CDK2/Cyclin A2复合蛋白结合位点空间变大, 先导分子与Lys33, Asp86, Lys129和Asp145残基之间的排斥作用有所降低, 导致结合自由能更大.     

Prediction of 5-hydroxytryptamine transporter inhibitors based on machine learning

In patients with depression, the use of 5-HT reuptake inhibitors can improve the condition. Machine learning methods can be used in ligand-based activity prediction processes. In order to predict SERT inhibitors, the SERT inhibitor data from the ChEMBL database was screened and pre-processed. Then 4 machine learning methods (LR, SVM, RF, and KNN) and 4 molecular fingerprints (CDK, Graph, MACCS, and PubChem) were used to build 16 prediction models. The top 5 models of accuracy (Q) in the cross-validation of training set were used to build three different ensemble learning models. In the test1 set, the VOT_CLF3 model had the largest SP (0.871), Q (0.869), AUC (0.919), and MCC (0.728). In the unbalanced test2 set, VOT_CLF3 had the largest SE (0.857), SP (0.867), Q (0.865) and MCC (0.639). VOT_CLF3 was recommended for the virtual screening process of SERT inhibitors. In addition, 12 molecular structural alerts that frequently appear in SERT inhibitors were found (P < 0.05), which provided important reference value for the design work of SERT inhibitors.     

2-氨基嘧啶对铜的缓蚀机理

利用动电位极化曲线、线性极化、X射线光电子能谱(XPS)、X射线俄歇能谱(X-AES)和表面增强拉曼散射(SERS)研究2-氨基嘧啶(2-AP)对金属铜的缓蚀作用。结果表明: 在含Cl~-离子的酸性介质中, 2-AP是铜的有效缓蚀剂; 随着介质pH值的增加, 2-AP的缓蚀能力降低。2-AP缓蚀能力随pH值明显变化的原因在于只有在酸性介质中, 质子化了的2-AP分子、Cl~-离子和铜表面原子(或离子)才可能形成保护作用强的多聚配合物膜。     

Acetylcholinesterase biosensor based on single-walled carbon nanotubes--Co phtalocyanine for organophosphorus pesticides detection

A simple and reliable technique has been developed for the construction of an amperometric acetylcholinesterase biosensor based on screen-printed carbon electrodes. For the first time, one-step modification using single-walled carbon nanotubes and Co phtalocyanine has been proposed to decrease the working potential and to increase the signal of thiocholine oxidation. The biosensor developed made it possible to detect 5-50 ppb of paraoxon and 2-50 ppb of malaoxon with detection limits of 3 and 2 ppb, respectively (incubation 15 min). The biosensor showed high reproducibility when measurements of the substrate and inhibitor were performed (R.S.D. about 1% and 2.5%, respectively). The reliability of the inhibition measurements was confirmed by testing spiked samples of sparkling and tape waters.