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Effect of residual dissolved oxygen on the corrosion behavior of low carbon steel in 0.1 M NaHCO3 solution

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Journal of Materials Science & Technology 2018年第8期34卷 1349-1358页

作者： Fang Xue Xin Wei Junhua Dong ini-Ibehe Nabuk Etim Changgang Wang Wei Ke Institute of Metal Research Chinese Academy of SciencesShenyang 110016China University of Science and Technology of China Hefei 230026China

The effect of residual dissolved oxygen （DO） on the corrosion behavior of carbon steel in 0.1 M NaHCO3 solution was investigated by electrochemical measurements, corrosion mass loss test, scanning electron microscopy （SEM） and X-ray diffraction （XRD）. In the initial immersion stage, the increase of the dissolved oxygen concentration led to the change of from a reductive state of active dissolution to an oxidizing state of pseudo passivation in low carbon steel. While in the final stage, all the steels transformed into the steady state of pseudo passivation. In the anaerobic solution, the formation of c^-FeOOH was attributed to the chemical oxidization of the ferrous corrosion products and the final cathodic process only included the reduction of c^-FeOOH, while in the aerobic solution, it included the reduction of oxygen and （x-FeOOH simultaneously. As the main corrosion products, the content of （x-FeOOH was increased while that of Fe6（OH）12CO3 was decreased with increasing concentration of dissolved oxygen. The total corrosion mass loss of the steel was promoted with the increase of dissolved oxygen concentration.

关键词： Low carbon steel Residual dissolved oxygen Electrochemical characterization Anodic dissolution state Pseudo passivation

Viscosity in water from first-principles and deep-neural-network simulations

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npj Computational Materials 2022年第1期8卷 1318-1327页

作者： Cesare Malosso Linfeng Zhang Roberto car Stefano Baroni Davide Tisi SISSA—Scuola Internazionale Superiore di Studi Avanzati 34136TriesteItaly Program in Applied and Computational Mathematics Princeton UniversityPrincetonNJ08544USA DP Technology Beijing100080PR China Department of Chemistry Department of Physicsand Princeton Institute for the Science and Technology of MaterialsPrinceton UniversityPrincetonNJUSA CNR Istituto Officina dei Materiali SISSA Unit34136TriesteItaly

We report on an extensive study of the viscosity of liquid water at near-ambient conditions,performed within the Green-Kubo theory of linear response and equilibrium ab initio molecular dynamics(AIMD),based on density-functional theory(DFT).In order to cope with the long simulation times necessary to achieve an acceptable statistical accuracy,our ab initio approach is enhanced with deep-neural-network potentials(NNP).This approach is first validated against AIMD results,obtained by using the Perdew–Burke–Ernzerhof(PBE)exchange-correlation functional and paying careful attention to crucial,yet often overlooked,aspects of the statistical data ***,we train a second NNP to a dataset generated from the Strongly Constrained and Appropriately Normed(SCAN)*** the error resulting from the imperfect prediction of the melting line is offset by referring the simulated temperature to the theoretical melting one,our SCAN predictions of the shear viscosity of water are in very good agreement with experiments.

关键词： viscosity Strongly ambient

Hepatocellular carcinoma treated with transarterial chemoembolization: Dynamic perfusion-CT in the assessment of residual tumor

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World Journal of Gastroenterology 2010年第47期16卷 5993-6000页

作者： Davide Ippolito Pietro Andrea Bonaff ini Laura Ratti Laura Antolini Rocco Corso Ferruccio Fazio Sandro Sironi Department of Diagnostic Radiology School of Medicine University of Milano-BicoccaH S. Gerardo Department of Clinical Medicine Prevention and Biotechnology Section of Medical Statistics H S. Gerardo Department of Clinical Medicine School of Medicine University of Milano-Bicocca H S. Gerardo Department of Interventional Radiology H S. Gerardo

AIM: To asses the value of computed tomography (CT)-perfusion in the detection of residual hepatocellular carcinoma (HCC) vascularization after transarterial chemoembolization (TACE). METHODS: Thirty-two consecutive patients were pro-spectively included in this study. All patients had liver cirrhosis and a conf irmed HCC lesion which was treated with TACE. One month after treatment, perfusion measurements of treated lesions were carried out. The CTperfusion (CT-p) protocol was performed with 16 slice multidetector computed tomography which included the following parameters: 8 dynamic slices/scan per 40 scans after iv injection of 50 mL of iodinated contrast (350 mg/mL) at a flow rate of 6 mL/s. Treated lesions were evaluated using dedicated perfusion software, which generated a quantitative colour map of perfusion. The following parameters were considered: hepatic perfusion (HP), arterial perfusion (AP), blood volume (BV), hepatic perfusion index (HPI), and time to peak (TTP). Perfusion parameters were described with quartile values of their distribution and statistically analyzed. RESULTS: Perfusion parameters of the treated lesions could be quantitatively assessed using CT-p analysis. The presence of residual tumor tissue was observed in 13 of the 32 patients. The values of the perfusion parameters measured within the relapse tissue were: HP (mL/100 g per minute): median = 44.4 (1stqt = 31.3, 3rdqt = 55.8); BV (mL/100 g): median = 18.7 (1stqt = 11.5, 3rdqt = 22.5); AP (mL/min): median = 39.0 (1stqt = 36.5, 3rdqt = 61.3); HPI (%): median = 34.0 (1stqt = 30.4, 3rdqt = 38.9); TTP (s): median = 17.3 (1stqt = 15.8, 3rdqt = 26.5). With the use of the univariate paired Wilcoxon signed rank test, HP, AP and HPI were shown to be significantly higher (P<0.001) in the relapse site than in the primary lesion. The BV and TTP parameters showed a tendency to be greater and lower, respectively, in the relapse site than in the primary lesion. CONCLUSION: In patients with HCC treat

关键词： Computed tomography-perfusion Functional-computed tomography Hepatocellular carcinoma Trans-arterial chemoembolization Tumour neo-angiogenesis

Electrochemical noise analysis on the pit corrosion susceptibility of biodegradable AZ31 magnesium alloy in four types of simulated body solutions

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Journal of Materials Science & Technology 2018年第10期34卷 1876-1884页

作者： changgang wang liping wu fang xue rongyao ma ini-ibehe nabuk etim xuehui hao junhua dong wei ke Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Magnesium alloys have been investigated as biodegradable implant materials since the last century. Non-uniform degradation caused by local corrosion limits their application, and no appropriate technology has been used in the research. In this study, electrochemical noise has been used to study the pit corrosion on magnesium alloy AZ31 in four types of simulated body solutions, and the data have been analyzed using wavelet analysis and stochastic theory. Combining these with the conventional polarization curves, mass loss tests and scanning electron microscopy, the electrochemical noise results implied that AZ31 alloy in normal saline has the fastest corrosion rate, a high pit initiation rate, and maximum pit growth probability. In Hanks＇ balanced salt solution and phosphate-buffered saline, AZ31 alloy has a high pit initiation rate and larger pit growth probability, while in simulated body fluid, AZ31 alloy has the slowest corrosion rate, lowest pit initiation rate and smallest pit growth probability.

关键词： Biodegradable magnesium alloy Electrochemical noise (EN) Pit corrosion susceptibilities Wavelet analysis Stochastic model

Corrosion Behaviour of carbon Steel Fasteners in Neutral Chloride Solution

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Acta Metallurgica Sinica(English Letters) 2022年第4期35卷 563-576页

作者： Enobong Felix Daniel Junhua Dong Xiaofang Li ini-Ibehe Nabuk Etim inime Ime Udoh Rongyao Ma Lei Chen Changgang Wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China Department of Marine Biology Akwa Ibom State UniversityP.M.B 1167UyoNigeria

An experimental model for simulating the corrosion of carbon steel fasteners(bolt and nut) composed of a contact carbon steel electrode(CCSE) and an exposed bare carbon steel plate electrode(BCSE) was designed. The effect of coupling on the corrosion process of the galvanically coupled carbon steel electrode was evaluated and compared with the self-corrosion process observed independently at the exposed and contact regions. Results obtained indicated that at an equal area ratio and uncoupled conditions, the corrosion rate is accelerated in the surface directly exposed to bulk solution compared to the bolt surface in contact with the nut. A coupling current was recorded when the exposed surface(BCSE) was electrically connected with the contact surface(CCSE);with the CCSE acting as the anode thereby suppressing the corrosion process in the exposed surface. By implication, the galvanic coupling between CCSE and BCSE increased the corrosion rate of CCSE. The diff erence in oxygen supply was responsible for the coupling effect observed in the system as there was no decrease in the solution pH. Moreover, varying the cathode-to-anode area( S c/S a) ratio significantly influenced the corrosion current density as increased S c/S a ratio resulted in an accelerated galvanic corrosion process. The corroded surfaces and interfaces were analysed using stereomicroscopy and scanning electron microscopy. X-ray diff ractometry was adopted for corrosion product characterization. The results obtained showed supportive evidence of the corrosion behaviour in carbon steel fasteners.

关键词： Bolt and nut Galvanic current density Zero resistance ammetry(ZRA) Coupling potential Differential aeration cell carbon steel fasteners

Effect of D-fructose on the in-vitro corrosion behavior of AZ31 magnesium alloy in simulated body fluid

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Journal of Materials Science & Technology 2021年第7期66卷 202-212页

作者： Durga Bhakta Pokharel Liping Wu Junhua Dong Xin Wei ini-Ibehe Nabuk Etim Dhruba Babu Subedi Aniefiok Joseph Umoh Wei Ke Shenyang National Laboratory for Materials Science(SYNL) Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Material Science and Engineering University of Science and Technology of ChinaHefei230026China Department of Marine Biology Akwa Ibom State UniversityUyoNigeria

The effect of addingd-fructose to simulated body fluid(SBF) on the corrosion behavior of AZ31 magnesium(Mg) alloy at 37.C and at a pH of 7.4 was studied by potentiodynamic polarization(PDP), electrochemical impedance spectroscopy(EIS), potentiostatic polarization and hydrogen(H2) collecting techniques,Raman spectroscopy technique, scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), X-ray diffraction(XRD), X-ray photoelectron spectroscopy analysis(XPS) and Fourier transformed infrared(FTIR). The results demonstrated that the addition of fructose enhanced the deposition of phosphates forming thick and compact corrosion products, which inhibited the transmission of aggressive ions into the Mg substrate. As a result, both the anodic dissolution of Mg and negative difference effect(NDE) were suppressed. Thus, the corrosion resistance of AZ31 Mgalloy in SBF was significantly improved.

关键词： AZ31 Mg alloy D-Fructose SBF EIS Hydroxyapatite

Finite-Size Conformational Transitions: A Unifying Concept Underlying Chromosome Dynamics

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Communications in Theoretical Physics 2014年第10期61卷 607-616页

作者： Bertrand R.caré Pascal carrivain Thierry Forné Jean-Marc Victor Annick Lesne Laboratoire de Physique Théorique de la Matière Condensée CNRS UMR 7600UPMC University Paris 06F-75005ParisFrance CNRS GDR 3536 UPMC University Paris 06F-75005ParisFrance Institut de Génétique Humaine CNRS UPR 1142 MontpellierFrance Institut de Génétique Moléculaire de Montpellier CNRS UMR 5535University of MontpellierMontpellierFrance Kavli Institute for Theoretical Physics China CAS

Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability distribution of some finite-size order parameter, and the evolution of this distribution as a control parameter varies. We demonstrate this claim for the coil-globule transition of a linear polymer and its mapping onto a two-state model. In a biological context, polymer models delineate the physical constraints experienced by the genome at different levels of organization,from DNA to chromatin to chromosome. We apply our finite-size approach to the formation of plectonemes in a DNA segment submitted to an applied torque and the ensuing helix-coil transition that can be numerically observed, with a coexistence of the helix and coil states in a range of parameters. Polymer models are also essential to analyze recent in vivo experiments providing the frequency of pairwise contacts between genomic loci. The probability distribution of these contacts yields quantitative information on the conformational fluctuations of chromosome regions. The changes observed in the shape of the distribution when the cell type or the physiological conditions vary may reveal an epigenetic modulation of the conformational constraints experienced by the chromosomes.

关键词： coil-globule transition helix-coil transition chromosome conformational capture two-state model

Inter-population variabilities in seed mass and germination of Panicum turgidum and Pennisetum divisum in the desert of Kuwait

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Journal of Arid Land 2020年第1期12卷 144-153页

作者： Arvind BHATT Narayana R BHAT Afaf AL-NASSER María M carÓN AndreaSANTO Kuwait Institute for Scientific Research Safat 24885Kuwait Laboratory of Botanical Research(LABIBO) Faculty of Natural SciencesNational University of Salta-CONICETSalta 4400Argentina Independent Researcher Selargius 09047Italy

Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation *** knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage *** in seed germination of Panicum turgidum Forssk and Pennisetum divisum(Gmel.)*** the desert of Kuwait was evaluated in different populations in May *** of seed germination(25 seeds and 4 replicates)was conducted for each population at night/day temperatures of 15℃/20℃and 20℃/30℃under the following light condition:continuous darkness or 12 h/12 h light/*** showed that seed masses of both species strongly varied according to their seed provenances,and both species produced heavier seeds in population with a higher soil electrical *** germination percentage considerably varied between two species,and the variation in *** was greater(17%–49%)than that of ***(72%–93%).Germination percentage in *** was greater at high temperature(20℃/30℃)than at low temperature(15℃/20℃).However,temperature regimes had no effect on germination percentage of *** *** germination time of both species exhibited significant inter-population *** result is especially relevant to assure the selection of the best population of each species and the regeneration success of the *** this,inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.

关键词： desert grass seed germination inter-population variability seed provenance seed dormancy

Effect of applied potential on the microstructure, composition and corrosion resistance evolution of fluoride conversion film on AZ31 magnesium alloy

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Journal of Materials Science & Technology 2018年第11期34卷 2084-2090页

作者： Liping Wu Changgang Wang Durga Bhakta Pokharel ini-Ibehe Nabuk Etim Lin Zhao Junhua Dong Wei Ke Nan Chen Environmental Corrosion Center Institute of Metal ResearchChinese Academy of Sciences

AZ31 magnesium（Mg） alloy was potentiostatic polarized in 0.1 M deaerated KF solution with pH 7.5 from-0.4 V to-1.4 V with an interval of-0.2 V. The polarization process was described by the potentiostatic current decay. The resultant film was analyzed by scanning electron microscopy（SEM）, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS） and electrochemical impedance spectroscopy（EIS）. The results demonstrated that the deposited film included a Mg（OH）2/MgF2 containing inner layer and a Mg（OH）-2/MgF2/KMgF3 comprising outer layer. The high polarized potential produced high content of MgF2 but low content of KMgF3 and thin film. Conversely, the low polarized potential produced small content of MgF2 but high content of KMgF3 and thick film. The optimal corrosion resistance of the deposited film was obtained at-1.4 V, which was closely related with the content of MgF2 and KMgF3 and the film thickness.

关键词： Potentiostatic Fluoride conversion film AZ33 magnesium alloy KF solution Corrosion