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OALib Journal期刊

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Effect of Nitrite Ions on Steel Corrosion Induced by Chloride or Sulfate Ions
Zhonglu Cao,Makoto Hibino,Hiroki Goda
International Journal of Corrosion , 2013, DOI: 10.1155/2013/853730
Abstract: The influence of nitrite concentration on the corrosion of steel immersed in three simulated pH environments containing chloride ions or sulfate ions has been investigated by comparing and analyzing the change of half-cell potential, the change of threshold level of or , the change of threshold level of / or / mole ratio, and the changes of anodic/cathodic polarization curves and Stern-Geary constant . The corrosivity of chloride ions against sulfate ions also has been discussed in pH 12.6, pH 10.3, and pH 8.1 environments containing 0, 0.053, and 0.2？mol/L , respectively. 1. Introduction The corrosion of reinforcing steel in concrete has become one of the most severe deterioration mechanisms in concrete structures. It is generally accepted that due to the high alkalinity of cement hydration products, a protective layer of iron oxides is formed on the surface of steel, which provides adequate corrosion resistance. However, with the penetration of chloride, sulfate, and carbon dioxide and the appearance of concrete cracking, this protective layer becomes unstable and corrosion initials. As one of the methods is to prevent steel corrosion, nitrite-based corrosion inhibitors, irrespective of being directly added into concrete during the mixing process or penetrating into concrete by the surface-applied remedial treatment, have been widely investigated in chloride-contaminated concrete [1–3], carbonated concrete [4–6], and cracked concrete [7, 8], and their inhibiting efficiencies also have been checked in simulated concrete pore solution, such as in highly alkaline solution [9–12], carbonated solution [12–14], and neutral and acid solution [12, 15]. Most of these results confirm the effectiveness of nitrite in increasing the chloride threshold level, delaying the onset of corrosion, and reducing the corrosion rate once the corrosion was initiated, but there is no general consensus on the / mole ratio above that the preservation of the passive state can be ensured; suggested values for this threshold range from 0.11 to 1.0 in concrete and from 0.07 to greater than 2 in simulated pore solution. This difference in the threshold level of / mole ratio obtained from various literatures might be due to the way of determining the concentrations of chloride and nitrite in concrete (free ions and total ions, etc.), the different qualities of mortar and concrete used in the experiments, the different components of simulated pore solution, and the different surface topographies and compositions of the steel. Comparing and analyzing these literatures, the authors find
Effect of Water-Cement Ratio on the Macrocell Polarization Behavior of Reinforcing Steel
Zhonglu Cao,Makoto Hibino,Hiroki Goda
Journal of Engineering , 2014, DOI: 10.1155/2014/925410
Abstract: The effect of water-cement ratio on the macrocell polarization behavior of reinforcing steel embedded in cement mortars was investigated by comparing and analyzing the macrocell polarization ratios and slopes of anodic and cathodic steels. Based on the experimental results, the relationship between macrocell potential difference and macrocell current density was also analyzed, and the mechanism of macrocell polarization affected by water-cement ratio was proposed. The results indicated that the water-cement ratios had little impact on the macrocell polarization ratios of cathode and anode. The lower water-cement ratio could reduce the macrocell current by decreasing the macrocell potential difference and increasing the macrocell polarization resistance of the cathode and anode. 1. Introduction The water-cement ratio (W/C ratio) is one of the important parameters affecting the long-term properties of reinforced concrete. For cement pastes hydrated to the same degree, as the water-cement ratio decreases, the permeability of reinforced concrete decreases as well. The permeability of reinforced concrete is a critical factor limiting the penetration of chloride and the diffusion of carbon dioxide, oxygen, and other aggressive agents and therefore plays an important role in controlling the microcell and macrocell corrosion behaviors of reinforcing steel. According to the study of Arya and Vassie [1], for the same area ratio of cathode to anode, a lower water-cement ratio, and hence lower permeability, could decrease the macrocell current flowing between cathodic steel and anodic steel. This lower current obtained from the lower permeability mix could probably be explained by the higher resistance of concrete and the lower transport rate of oxygen and ferrous ions, producing restrictions to the cathode and anode reaction kinetics. Similar results could be confirmed by the study of Vedalakshmi et al. [2], Hansson et al. [3], and Ohno et al. [4–7]. The results of Raupach [8] indicated that a reduction of the water-cement ratio from 0.6 to 0.5 yielded a further reduction in steel mass loss in the crack zone. This influence was especially pronounced after 24 weeks and then became much smaller after one year, which might be explained by the fact that the period up to depassivation was prolonged by a reduction of the water-cement ratio. However, after the onset of corrosion, the water-cement ratio had only a negligible influence. All these studies as mentioned above only investigated the effect of water-cement ratio on the magnitude of macrocell current and did not
Event-Related Potential Effects Associated with Insight Problem Solving in a Chinese Logogriph Task  [PDF]
Qiang Xing, John X. Zhang, Zhonglu Zhang
Psychology (PSYCH) , 2012, DOI: 10.4236/psych.2012.31011
Abstract: The electrophysiological correlates of insight and non-insight problems solving were studied using event- related potentials (ERPs). Participants were given some time to guess Chinese logogriphs and then presented with an answer to judge whether it matched the logogriph. Results showed that the insight trials elicited a more negative ERP deflection (N300-500) than did the non-insight trials in most scalp regions. In a later time window from 600 ms to 1100 ms, the insight trials elicited a more positive ERP deflection (P600-1100) than the non-insight trials, mostly in central regions. The results indicate that the early N300-500 effect may reflect cognitive conflict resulting from the breaking of mental set and the later P600-1100 effect may be related to the formation of novel associations, both crucial to the occurrence of insight.
(E)-N′-(5-Bromo-2-hydroxybenzylidene)-4-hydroxy-3-methoxybenzohydrazide methanol solvate
Shi-Yong Liu,Zhonglu You
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810022063
Abstract: In the title compound, C15H13BrN2O4·CH4O, the two benzene rings form a dihedral angle of 3.2 (2)°. An intramolecular O—H...N hydrogen bond is observed. In the crystal structure, molecules are linked through O—H...O and N—H...O hydrogen bonds, forming a two-dimensional network parallel to (10overline{1}).
(E)-N′-(4-Hydroxybenzylidene)-2-nitrobenzohydrazide
Shi-Yong Liu,Zhonglu You
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810022075
Abstract: In the title compound, C14H11N3O4, the two benzene rings form a dihedral angle of 45.3 (3)°. The nitro group is twisted out of the attached ring by a dihedral angle of 37.5 (3)°. In the crystal structure, molecules are linked into a two-dimensional network parallel to (100) by O—H...O and N—H...O hydrogen bonds.
(E)-N′-(5-Bromo-2-hydroxybenzylidene)-2-methoxybenzohydrazide
Shi-Yong Liu,Zhonglu You
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810022002
Abstract: In the title compound, C15H13BrN2O3, the molecule adopts an E configuration about the C=N bond and the two benzene rings form a dihedral angle of 20.3 (3)°. In the molecule, there are two intramolecular hydrogen bonds, viz. O—H...N and N—H...O, involving the hydroxy substituent, the methoxy O atom and the hydrazide NH group and N atom. In the crystal structure, molecules are linked through N—H...O hydrogen bonds, forming chains propagating along [010].
2-Cyano-N′-[1-(2-hydroxyphenyl)ethylidene]acetohydrazide monohydrate
Hongbo Li,Peng Chen,Zhonglu You
Acta Crystallographica Section E , 2011, DOI: 10.1107/s1600536811042565
Abstract: The title compound, C11H11N3O2·H2O, was obtained by the reaction of 2-acetylphenol with cyanoacetohydrazide in methanol. The asymmetric unit contains two hydrazone molecules and two water molecules of crystallization. There is an intramolecular O—H...N hydrogen bond in each hydrazone molecule. The crystal structure is stabilized by intermolecular N—H...O, O—H...O and O—H...N hydrogen bonds.
{(E)-2-Bromo-4-chloro-6-[3-(dimethylammonio)propyliminomethyl]phenolato}dichloridozinc(II)
Li-Juan Ye,Zhonglu You
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808016255
Abstract: The title compound, [ZnCl2(C12H16BrClN2O)], is a mononuclear zinc(II) complex. The ZnII atom is four-coordinate in a tetrahedral geometry, binding to the phenolate O and imine N atoms of the zwitterionic Schiff base ligand and to two Cl ions. In the crystal structure, molecules are linked through intermolecular N—H...Cl hydrogen bonds to form chains running along the a axis.
Realization of a reversible switching in TaO2 polymorphs via Peierls distortion for resistance random access memory
Linggang Zhu,Jian Zhou,Zhonglu Guo,Zhimei Sun
Physics , 2015, DOI: 10.1063/1.4913904
Abstract: Transition-metal-oxide based resistance random access memory is a promising candidate for next-generation universal non-volatile memories. Searching and designing appropriate new materials used in the memories becomes an urgent task. Here, a new structure with the TaO2 formula was predicted using evolutionary algorithms in combination with first-principles calculations. This new structure having a triclinic symmetry (T-TaO2) is both energetically and dynamically more favorable than the commonly believed rutile structure (R-TaO2). Our hybrid functional calculations show that T-TaO2 is a semiconductor with a band gap of 1.0 eV, while R-TaO2 is a metallic conductor. This large difference in electrical property makes TaO2 a potential candidate for resistance random access memory (RRAM). Furthermore, we have shown that T-TaO2 is actually a Peierls distorted R-TaO2 phase and the transition between these two structures is via a directional displacement of Ta atoms. The energy barrier for the reversible phase transition from R-TaO2 to T-TaO2 is 0.19 eV/atom and the other way around is 0.23 eV/atom, suggesting low power consumption for the resistance switch. The present findings provide a new mechanism for the resistance switch and will also stimulate experimental work to fabricate tantalum oxides based RRAM.
High-precision thermal ionization mass spectrometry dating of young volcanic rocks by using U-series method
Fei Wang,Zicheng Peng,Wenji Chen,Zhaorong Wang,Jiwu Yang,Zhonglu Zhang,Yutai Hu
Chinese Science Bulletin , 2000, DOI: 10.1007/BF02884910
Abstract: A high precision thermal ionization mass spectrometric (HP-TIMS) technique is used to determine238U,234U,232Th,230Th concentrations and their ratios in whole rocks and minerals separated from Quaternary Maanshan, Dayingshan and Heikongshan volcanic rocks of Tengchong volcanic field, Yunnan Province, China. The238U-230Th isochrons are given, yielding four age values (227±20) ka (D-1, Dayingshan), (79.6±5.5) ka (D-7, Dayingshan), (21.9±3.0) ka (h-1, Heikongshan), and (7.5±1.0) ka (M-1, Maanshan). The result is not only consistent with but also preciser than those measured by the K-Ar method and the alpha spectrometry U-series method, indicating that the HP-TIMS method is reliable and has high precision. Besides, a procedure of HP-TIMS analysis of young volcanic rocks in China is set up preliminarily.
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