喀斯特塌陷机理研究

由于过量开采地下水或矿山大降深排水,引起Ⅲ水动力带内天然流场的巨大变化,这种人为因素才是产生大面积塌陷的机理。在均匀状巨厚灰岩水动力剖面上存在四个水动力带,其中Ⅲ与Ⅳ带的水动力特征不同,两者之间存在“双层水位”关系。国内已有少数矿山排水疏干放在Ⅳ带,能起到疏干效益,所形成的降落漏斗对Ⅲ带的天然流场不发生太大影响,也就不致引起塌陷。

柿竹园野鸡尾矿区地面塌陷成因分析及防治

讨论了野鸡尾矿区地面塌陷分布的特征,并对塌陷的成因进行了分析,认为塌陷是潜蚀、吸蚀、气爆等综合作用的结果,岩溶管道中水动力条件的改变,最终导致地面塌陷的发生,最后提出了地面塌陷的防治措施。

斗笠山矿区岩溶塌陷分布规律及成因探讨

由于矿井长期疏排地下水 ,导致地表下沉、开裂直至形成塌陷 ,初步讨论了岩溶塌陷分布规律 ,并对塌陷的成因机理进行分析 ,认为塌陷的过程是潜蚀、吸蚀、气爆的作用过程 ,得出岩溶管道的水动力条件改变 ,最终导致塌陷的产生 ,对岩溶矿区的防治工作也必须从这些实际情况出发 ,才能达到治本的目的。

江夏法泗岩溶塌陷区冲孔桩施工引发岩溶塌陷的成因机理

依托武汉市岩溶地面塌陷区监测系统,开展江夏法泗冲孔桩施工过程裂隙岩溶含水层的水位、水压力和影响半径等关键参数的动态监测,研究施工过程岩溶含水层水压力的动态响应,探讨其诱发覆盖层突然塌陷的成因机理,结果表明:在第四系孔隙承压水含水层施工时,对该含水层的影响较大,但水位变幅相对较为平缓;在碳酸盐岩裂隙岩溶水含水层施工时,由于含水介质的不均一性,未揭穿岩溶通道时,对岩溶水的影响较小;当揭穿岩溶通道时,岩溶水水位可能产生突增,此时,诱发岩溶地面塌陷的风险加大。

Influence of adipic acid on anodic film formation and corrosion resistance of 2024 aluminum alloy

The influence of adipic acid on the formation and corrosion resistance of anodic oxide film fabricated on 2024 aluminum alloy was investigated. The morphology was investigated by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）, respectively. The corrosion resistance was evaluated by electrochemical impedance spectroscopy （EIS）. The results showed that the adipic acid was absorbed at the electrolyte/anodic layer interface during anodizing. The corrosion rate of anodic film decreased and the film thickness increased. The film was uniform and compact especially at the film/substrate interface. After sealing procedure, anodic film formed with the addition of adipic acid exhibited improved dielectric property and corrosion resistance in aggressive environment.

An Air-Breathing Micro Direct Methanol Fuel Cell with 3D KOH-Etched Cathode Structure

A micro direct methanol fuel cell （μDMFC） using MEMS technology is reported. The prototype features a unique 3D air-breathing cathode structure fabricated using KOH etching and double-side lithography. The optimization of the MEMS fabrication process is analyzed. The experimental results show the prototype generates a maximum power density of 2.52mW/cm^2 at room temperature. This performance is better than the published resuits of other silicon-based passive μDMFCs. Moreover,it is comparable with that of our previous active μDMFCs which require an external pump, certificating the feasibility of this new configuration.

练兵场

山东省军区举办车辆强制性保养集训班 为贯彻落实总部、军区关于加强车辆保养工作的通知精神,按时保质保量地完成车辆强制性保养任务,山东省军区于1995年3月上旬,在烟台警备区举办了一期车辆强制性保养集训班。参加集训人员有海防部队装备技术部门分管车辆工作的科长、修理所长和技术骨干等40人。这次集训,采取了学习文件、观看录相、

Adsorption isotherm mechanism of amino organic compounds as mild steel corrosion inhibitors by electrochemical measurement method

The inhibition ability of 4-amino-5-phenyl-4H-1, 2, 4-trizole-3-thiol （APTT）, ethylenediaminetetra-acetic acid （EDTA） and thiourea （TU） for mild steel corrosion in 1.0 moFL HC1 solution at 30 ℃ was investigated. Tafel polarization and electrochemical impedance spectroscopy （EIS） were used to investigate the influence of these organic compounds as corrosion inhibitors of mild steel in 1.0 mol/L HC1 solution at 30 ℃. The inhibition mechanism was discussed in terms of Langrnuir isotherm model. Results obtained from Tafel polarization and impedance measurements are in a good agreement. The inhibition efficiency increases with the increase of the inhibitor concentration. The adsorption of the inhibitors on the mild steel surface follows Langmuir adsorption isotherm and the free energy of adsorption AGads indicates that the adsorption of APTT, EDTA, and TU molecules is a spontaneous process and a typical chemisorption.

Eco-friendly corrosion inhibitor from Pennisetum purpureum biomass and synergistic intensifiers for mild steel

Extracts of elephant grass （Penniseturn purpureum） blended with some intensifier halides like ammonium chloride （AMC） and potassium iodide （PTI） were investigated as corrosion inhibitor for mild steel. The corrosion process was monitored in 3.5% HCI by mass loss and electrochemical techniques at 30, 40, 50, 60 and 90 ℃. Addition of AMC and PTI increased the inhibition efficiency with the highest inhibition efficiency obtained with PTI blend- ed extract. The blends behaved as mixed type inhibitors and were spontaneously adsorbed on mild steel surface in exothermic nature. Synergistic parameters of the intensifier ions revealed cooperative effect. Kinetic data treatment indicated increase in energy barrier by intensifier ions. The results demonstrate that elephant grass extract blended with halide ions can act as alternative ecofriendly inhibitor for mild steel at elevated temperatures.

Microstructure and properties of co-continuous(β-TCP+MgO)/Zn-Mg composite fabricated by suction exsorption for biomedical applications

The biomedical co-continuous(β-TCP+MgO)/Zn-Mg composite was fabricated by infiltrating Zn-Mg alloy into porousβ-TCP+MgO using suction exsorption technique.The microstructure,mechanical properties and corrosion behaviors of the composite were evaluated by means of scanning electron microscopy(SEM),X-ray diffraction(XRD),mechanical testing,electrochemical and immersion test.It was found that the molten Zn-Mg alloy had infiltrated not only into the pores but also into the struts of the porousβ-TCP+MgO scaffold to form a compact composite.The Zn-Mg alloy contacted to theβ-TCP+MgO scaffold closely,and no reaction layer can be found between the alloy and the scaffold.The compressive strength of the composite was as high as244MPa,which was about1000times higher than that of the original porousβ-TCP+MgO scaffold and2/3of the strength of the Zn-Mg bulk alloy.The electrochemical and immersion tests in simulated body fluid(SBF)solution indicated that the corrosion resistance of the composite was better than that of the Zn-Mg bulk alloy.The corrosion products on the composite surface were mainly Zn(OH)2.Appropriate mechanical and corrosion properties indicated that the(β-TCP+MgO)/Zn?Mg composite fabricated by suction exsorption would be a very promising candidate for bone substitute.

Transport simulation of sorptive contaminants considering sediment-associated processes

Sediment-associated processes, such as sediment erosion, deposition, and pore water diffusion/advection affect sorptive contaminant transport. By considering these processes, we developed an equation to simulate contaminant transport. Erosion and deposition processes are considered as erosion and deposition fluxes of sediment, and adsorption-desorption processes of contaminants by sediment are simulated using the Langmuir Equation. Pore water diffusion is calculated based on the contaminant concentration gradient across the sediment-water interface. Pore water advection is estimated using pore water contained in the sediments of erosion flux. The equation is validated to simulate total phosphorus concentrations in Guanhe estuary in the northern Jiangsu, China. The simulated total phosphorus concentrations show better agreement with field observations compared to estimations that do consider sediment-associated processes.

Ethanol Extract of Vitex Doniana as a Green Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Medium

Corrosion is a costly and complicated problem facing mild of Vitex doniana as a corrosion inhibitor for mild steel in HCI medium steel utility. This study investigated the use of ethanol extract Experimental methods used are gravimetric and thermometric The results showed that corrosion rate decreased as the concentration of ethanol extract of Vitex doniana increased and with decrease in temperature. Vitex doniana extract obeyed Langmuir and Tempkin adsorption isotherm. Physical adsorption was proposed from △G° and Ea. Inhibition efficiency （1%） and the degree of surface coverage （0） were calculated and all indicated that Vitex doniana was a good corrosion inhibitor.

New Synthesized （3-（3,4-dimethoxyphenyl）isoxazole-5- yl） Methanol as Corrosion Inhibitor on Steel in 1 M HCI

The inhibition of corrosion of steel in molar hydrochloric acid solution by new synthesized DMI （（3-（3,4-dimethoxyphenyl）isoxazole-5-yl） methanol） compound is studied by weight loss and electrochemical polarization measurements. The two methods give consistent results. The polarization curves indicate that the DMI compound acts as mixed-type inhibitor. This compound is efficient inhibitor. The inhibition efficiency increases with the increase of inhibitor concentration to reach 96% at 10-3 M for DMI. The temperature effect on the corrosion behavior of steel in 1 M HCI with and without the DMI compound at 10-3 M is studied in the temperature range from 298 to 318 K. The adsorption of inhibitor on the steel surface is found to obey the Frumkin adsorption isotherm model. From the adsorption isotherm, some thermodynamic data for the adsorption process （f, K and △Gads） are calculated and discussed.

DFT Study of Metal Atoms Adsorbed at Low-coordinated Sites of MgO (001) Surface

The adsorption of metal atoms, Ni, Pd, Pt, Cu, Ag and Au, at low-coordinated edge and corner oxygen sites of MgO (001) surface has been studied theoretically by using density functional method with cluster models embedded in a large array of point charges. For comparison, the interaction of metal atoms with perfect regular oxygen site of MgO (001) surface was also calculated. As regards these metal atoms adsorbed at perfect oxygen sites of MgO (001) surface, Cu, Ag and Au are very weakly bonded to the surface of MgO; Ni, Pd and Pt, on the other hand, exhibit strong interactions with perfect oxygen sites of MgO (001) surface; the large adsorption energy shows that there exist strong bonds formed between these metal atoms with surface oxygen sites. For the metal atoms adsorbed at edge and corner sites, the adsorption energy is much increased, consistent with our previous study of CO and Cl2 adsorption on MgO (001) surface. This illustrates that the low-coordinated sites, especially corner site, are more advantageous positions for those metal atoms adsorbed on MgO (001) surface. The Mulliken population analysis indicates that the electron transferred from MgO to the metal atoms were increased with the decrease of the coordination numbers, which may be one of the reasons for changing catalytic efficiency and selectivity of the metal particles supported by MgO.

Corrosion inhibition and mechanism of mild steel in hydrochloric acid by ceftriaxone and amoxicillin

Corrosion inhibition of mild steel in 1 mol/L HC1 by amoxicillin and ceftriaxone in the concentration range of 1.00×10^-5-1.00×10^-2 mol/L has been studied using weight loss, electrochemical potentiodynamic polarization, electrochemical impedance spectroscopy （EIS）, scanning electron microscopy （SEM） and quantum chemistry tests at 298 K. The weight loss experiment showed that the inhibition efficiency increased with amoxicillin and ceftriaxone concentrations to attain the maximums of 80.3% and 94.1%, respectively at 1.00×10^-2 mol/L. Potentiodynamic polarization indicated that amoxicillin and ceftriaxone acted as mixed-type inhibitors but mainly inhibited cathode hydrogen evolution reaction for mild steel in 1 mol/L HC1. The electrochemical impedance spectroscopy （EIS） demonstrated the inhibitors covered the active points of metal surface to inhibit corrosion. The absorption of both inhibitors on the mild steel surface was found to follow Langmuir adsorption isothermal and dominantly involve chemical adsorption at 298 K. Scanning electron microscopy （SEM） confirmed both of the inhibitors played a significant protective effect in mild steel corrosion in 1 mol/L HC1. The relationship between the inhibition properties and molecular structure had been discussed by quantum chemistry calculation. All the experimental results concluded that both amoxicillin and ceftriaxone acted as good corrosion inhibitors and their inhibition efficiency was in the order of ceftriaxone 〉 amoxicillin.