Scanning microelectrochemical characterization of the anti-corrosion performance of inhibitor films formed by 2-mercaptobenzimidazole on copper

The aim of this work is to explore the applicability of the scanning electrochemical microscope (SECM) to characterize the inhibiting effect of 2-mercaptobenzimidazole against the corrosion of copper. SECM was operated in the feedback mode by using ferrocene-methanol as redox mediator, and the sample was left unbiased at all times. The kinetic changes in the corrosion processes were monitored over time from the Z-approach curves. Furthermore, inhibitor-modified copper samples presenting various surface finishes were imaged by SECM and the scanning vibrating electrode technique (SVET), allowing changes both in the surface activity of metal-inhibitor films and in the extent of corrosion attack to be spatially resolved. Differences in the local electrochemical activity between inhibitor-free and inhibitor-covered areas of the sample were successfully monitored.     

Vitamin C Enhances Vitamin E Status and Reduces Oxidative Stress Indicators in Sea Bass Larvae Fed High DHA Microdiets

Docosahexaenoic acid (DHA) is an essential fatty acid necessary for many biochemical, cellular and physiological functions in fish. However, high dietary levels of DHA increase free radical injury in sea bass (Dicentrarchus labrax) larvae muscle, even when vitamin E (α-tocopherol, α-TOH) is increased. Therefore, the inclusion of other nutrients with complementary antioxidant functions, such as vitamin C (ascorbic acid, vitC), could further contribute to prevent these lesions. The objective of the present study was to determine the effect of vitC inclusion (3,600?mg/kg) in high DHA (5?% DW) and α-TOH (3,000?mg/kg) microdiets (diets 5/3,000 and 5/3,000?+?vitC) in comparison to a control diet (1?% DHA DW and 1,500?mg/kg of α-TOH; diet 1/1,500) on sea bass larvae growth, survival, whole body biochemical composition and thiobarbituric acid reactive substances (TBARS) content, muscle morphology, skeletal deformities and antioxidant enzymes, insulin-like growth factors (IGFs) and myosin expression (MyHC). Larvae fed diet 1/1,500 showed the best performance in terms of total length, incidence of muscular lesions and ossification degree. IGFs gene expression was elevated in 5/3,000 diet larvae, suggesting an increased muscle mitogenesis that was confirmed by the increase in the mRNA copies of MyHC. vitC effectively controlled oxidative damages in muscle, increased α-TOH larval contents and reduced TBARS content and the occurrence of skull deformities. The results of the present study showed the antioxidant synergism between vitamins E and C when high contents of DHA are included in sea bass larvae diets.     

Interference of EDTA in the treatment of metal plating wastewater by biosorption

BACKGROUND: The applicability of biosorption for the treatment of metal plating wastewater is adversely affected by the presence of complexing agents. To investigate this limitation on the removal of copper(II) onto peat, batch and column experiments were carried out using EDTA as the model complexing agent. The influence of pH and copper(II):EDTA mass ratios were evaluated for copper(II) concentrations between 5 and 100 mg Cu(II) dm^?3. RESULTS: EDTA negatively affected the copper(II) uptake of peat for pH > 5. Batch and column experiments showed that copper(II)‐EDTA complexes were not sorbed by peat. The leaks of copper(II) detected from the beginning of the column operation matched the copper(II)‐EDTA concentration in the feed solutions. To overcome the interference of EDTA, a novel approach based on the combination of peat + activated carbon was proposed. Nearly complete removal of copper(II) was maintained over 70 h in the treatment of a solution containing 20 mg Cu(II) dm^?3 with 11% of copper(II)‐EDTA complexes. CONCLUSION: A new mass transport model coupling copper(II) speciation in the feed and mass transfer rate‐controlled process simulated the copper(II) breakthrough curves in the presence of EDTA and could be used to successfully predict the breakthrough point. This work demonstrated that biosorption can also be applied for the treatment of wastewater containing complexing agents with the proper combination of sorbent materials. © 2012 Society of Chemical Industry     

不同压力下的热压加工对含Mn块体纳米晶Fe3Al组织和性能的影响

对铝热反应熔化制备的含10wt%Mn块体纳米晶Fe3Al材料在800℃和1000℃温度下,采用不同压力进行热压加工,利用XRD研究热压加工前后纳米晶粒尺寸的变化,并测试硬度变化和压缩率。结果显示,不同温度、压力下热压加工后,晶粒尺寸变化不大;热压加工后,材料的硬度有所上升,但温度和压力对硬度影响不大;热压加工中,材料表现出较好的塑性变形,并随着热压压力的增大,材料压缩率逐渐增大,但温度对材料的压缩率影响不明显。热压加工后,块体纳米晶Fe3Al材料几何尺寸得到了增大。     

Examination of organic coatings on metallic substrates by scanning electrochemical microscopy in feedback mode: Revealing the early stages of coating breakdown in corrosive environments

Scanning electrochemical microscopy in feedback mode was used to monitor changes in the surface state of a polymeric film applied on a metallic substrate when exposed to an aqueous electrolytic environment. The protected metal consisted of a carbon steel substrate coated with a polyurethane-based polymeric film. SECM measurements performed in the presence and absence of chloride anions permitted a specific effect caused by Cl⁻ anions at early exposures to be detected. Significant surface roughening is observed for immersion times shorter than 1 day when the electrolyte contains chloride ions. Additionally, the growth of an individual blister could also be investigated.     

关于定量界定设备修理周期若干问题的研究

本文通过对确定设备修理周期经验公式的讨论,指出了两点不足。对此笔者提出了:在生产过程中运用单位产品维修成本与产量的量化模型,从经济效益的角度动态界定最佳修理周期的设想,以期在设备维修管理方面,为企业提供最佳经济效益。并由此得出了几点有益的启示。     

利用开关卡尔曼滤波器的目标跟踪技术研究

为了使机器人视觉伺服控制系统的目标跟踪精度得到进一步提高,构建一种基于开关卡尔曼滤波器的视觉伺服控制系统。研究视觉伺服的目标跟踪原理,推导相关的数学模型,并分析跟踪误差产生的原因;针对图像采集和处理引入的延时问题,通过卡尔曼滤波估计得到目标运动的速度信息,以此作为前馈量输入视觉伺服控制器,补偿由于目标运动和延时造成的跟踪误差;为了解决卡尔曼滤波器由于目标运动的突然变化而降低估计性能的问题,引入运动监视器以在目标运动突然变化时发出开关信号并重置卡尔曼滤波器;最后对该算法进行实验与仿真。结果表明:基于卡尔曼滤波器的视觉伺服控制器能把跟踪误差控制在1 mm以内,而开关卡尔曼滤波器能有效地减少因目标运动状态突然变化而产生的跟踪误差。     

Experimental evidence of an upper limit for hydrogen storage at 77 K on activated carbons

An upper limit for hydrogen storage at 77 K on activated carbons was clearly observed in the present experimental work. Such a limit is around 6.4 wt.%, i.e., close to the theoretical limit of 6.8 wt.%. Results of hydrogen storage were obtained in three independent laboratories using volumetric and gravimetric devices. Lab-made activated carbons (ACs) were found to have higher capacities than those of the commercial material AX-21. A maximum excess hydrogen storage capacity of 6.0 wt.% at 77 K and 4 MPa was obtained. This maximum was reduced to 0.6 wt.% at 298 K and 5 MPa. ACs with surface areas (S_BET) as high as 3220 m² g⁻¹ were prepared from chemical activation of anthracites with alkali (Na and K) hydroxides. At 77 K and 4 MPa, excess hydrogen storage capacity was directly correlated with S_BET for ACs having S_BET values lower than 2630 m²/g. Hydrogen uptake at 77 K also correlated with micropore volume and strongly depended on average pore diameter.     

Influence of the co-firing on the leaching of trace pollutants from coal fly ash

The (co)-firing of low-cost alternative fuels is expected to increase in the forthcoming years in the EU because of the economic and environmental benefits provided by this technology. This study deals with the impact of the different coal/waste fuel ratio of the feed blend on the mineralogy, the chemical composition and especially on the leaching properties of fly ash. Different blends of coal, petroleum coke, sewage sludge, wood pellets, coal tailings and other minor biomass fuels were tested in PCC (pulverised coal combustion) and FBC (fluidized bed combustion) power plants. The co-firing of the studied blends did not drastically modify the mineralogy, bulk composition or the overall leaching of the fly ash obtained. This suggests that the co-firing process using the alternative fuels studied does not entail significant limitations in the re-use or management strategies of fly ash.