Synergistic inhibition between o-phenanthroline and chloride ion for steel corrosion in sulphuric acid

The corrosion inhibition of cold rolled steel in 0.5 M sulphuric acid in the presence of o-phenanthroline and sodium chloride (NaCl) has been investigated by using weight loss and electrochemical techniques. The experimental data suggest that the inhibition efficiency increases with increasing NaCl concentration in the presence of 0.0002 M o-phenanthroline, but decreases with increasing temperature. A synergistic effect is observed when o-phenanthroline and chloride ions are used together to prevent cold rolled steel corrosion in 0.5 M sulphuric acid. The polarization curves showed that the complex of o-phenanthroline and NaCl acts as a mixed type inhibitor. The experimental results suggested that the presence of chloride ions in the solution stabilized the adsorption of o-phenanthroline molecules on the metal surface and improved the inhibition efficiency of o-phenanthroline. The adsorption of the complex accords with the Langmuir adsorption isotherm. Some thermodynamic parameters such as adsorption heat, adsorption entropy and adsorption free energy have been calculated by employing thermodynamic equations. Kinetic parameters such as apparent activation energy and pre-exponential factor have been calculated and discussed.     

Preparation and properties of nanosize MnZn ferrite from δ-FeOOH

Ferrous ion was transformed into feroxyhyte (δ-FeOOH) by oxidation. Then, manganese sulfate and zinc sulfate in some ratio were added to the feroxyhyte solution. The co-precipitation was boiling reflux conditions sometime under constant stirring. The nanosize MnZn ferrite powder was formed. The mechanism of preparation of the nanosize MnZn ferrite was discussed, and the formation of feroxyhyte which was playing a key role during the process was mentioned. The properties of powder was tested by means of X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results show that the samples of spherical particles about 20 nm, which have characteristics of ferrimagnetism, has larger saturation magnetization, but the remanent magnetization and coercivity are comparatively smaller. The spinel MnZn ferrite nanosize powder was successfully prepared from δ-FeOOH at low temperature, with low-carbon steel and peroxide as main material.     

圆柱体相贯线上的圆角表示方法

在机械设计中，圆柱体相贯线上的圆角表示方法是CAD和计算机辅助设计中的难题，所有的CAD／CAM软件都没有这一功能，多数使用者采用的是各种近似方法。本文介绍了严密精确的设计和几何造型方法，可用于大型铸锻件和重型机械的CAD和计算机辅助设计。     

高层住宅结构设计

主要介绍长沙梦泽园高层住宅从基础到上部楼层各部位的结构设计,以及在设计、施工过程中所考虑的一些问题及处理方法。     

Effect of surface free energy on the adhesion of biofouling and crystalline fouling

Pipelines and heat exchangers using seawater as coolant suffer from biofouling. Biofouling not only reduces heat transfer performance significantly, but also causes considerable pressure drop, calling for higher pumping requirements. It would be much more desirable if surfaces with an inherently lower stickability for biofouling could be developed. In this paper, a cost-effective autocatalytic graded Ni-Cu-P-PTFE composite coating with corrosion-resistant properties was applied to reduce biofouling formation. The experimental results showed that the surface free energy of the Ni-Cu-P-PTFE coatings, which were altered by changing the PTFE content in the coatings, had a significant influence on the adhesion of microbial and mineral deposits. The Ni-Cu-P-PTFE coatings with defined surface free energy reduced the adhesion of these deposits significantly. The anti-bacterial mechanism of the composite coatings was explained with the extended DLVO theory.     

几种重氮氨基类新显色剂的合成及其与镉（Ⅱ）显色反应的研究

3种重氮氨基类新显色剂的合成及其与镉(Ⅱ)的显色反应。在表面活性剂 Triton X-100存在下,3种试剂均与镉(Ⅱ)生成络合比为3:1的红色络合物。其表观摩尔吸光系数在1.80×10~5以上。镉量在0～12μg/25mL 符合比尔定律。并对3种试剂的性能与结构的关系作了比较。将其中一种试剂(BPDAA)用于废水中痕量镉的测定,结果满意。     

建筑供排水用聚丙烯管道(PP-R)特性简析

PP -R管道具有质轻、连接方便、良好耐热性和较小导热系数、耐腐蚀且管道阻力小等优点 ,属绿色产品 ,本文对施工过程中就PP -R管与混凝土的粘结不密、抗紫外性能差等问题提出了相应的处理措施     

Analysis of the oscillatory behavior of double-walled carbon nanotube-based oscillators

Molecular dynamics simulations of oscillatory behaviors of double-walled carbon nanotube-based oscillators are performed. The second-generation empirical bond-order potential is used for the atomic interactions within a wall, and a registry-dependent and four different registry-independent van der Waals potentials are used for the atomic interactions between walls. It is found that the frequencies of the nanotube oscillators are sensitive to the choice of the van der Waals potentials. An almost non-decay oscillation is observed for the registry-dependent potential when there is no rocking motion. However, an apparent decay oscillation is observed when rocking motion occurs. A decay oscillation is observed for all registry-independent potentials even without rocking motion. Mechanisms leading to unstable oscillatory behavior are analyzed.     

Abrasion erosion of concrete by water-borne sand

Hydraulic concrete structures frequently experience long-term abrasive erosion by water-borne sand, resulting in surface damage and eventually limiting their service life. In this study, the investigation of abrasion erosion tests on concrete with various water to cementitious material ratios (w/cm) was performed. The effects of the constituent materials on concrete structure abrasion erosion resistance were studied. The test results show that: (1) reduction in the w/cm ratio increases the tested concrete abrasion resistance; (2) the splitting tensile strength is a viable indicator for concrete abrasion resistance; (3) high permeability concrete exhibits weak abrasion resistance; and (4) concrete and low strength concrete made with coarser aggregate exhibit greater abrasion resistance.     

Simultaneous recovery of copper and surfactant by an electrolytic process from synthetic solution prepared to simulate a concentrate waste stream of a micellar-enhanced ultrafiltration process

Electroplating method was employed to recover copper and surfactant simultaneously from synthetic solutions prepared to simulate concentrated waste stream generated from micellar-enhanced ultrafiltration. Effects of surfactant and copper (II) concentrations, surfactant to copper (II) molar ratio (S/M), electroplating voltage and time, solution pH, and ionic strength on metal recovery and electrical current efficiency were investigated. Results show that at a fixed S/M ratio of 5, the first-order kinetic constant for Cu (II) removal by electroplating increases with decreasing SDS concentration. At fixed SDS concentration of 8.5 mM, increasing initial Cu (II) concentration increases both Cu (II) recovery and current efficiency. Electrolyte pH has profound effects on the metal recovery and current efficiency due to the difference in solution conductivity after pH adjustment and the extent of Cu (II) adsorption onto SDS at different pHs.