Evaluation of microbially influenced corrosion with electrochemical noise analysis and signal processing

Corrosion behaviors of stainless steel (SS304), with attached Acidithiobacilus ferrooxidans (ATF) bacteria and exposed to three different types of artificial saliva solutions, namely: (1) Jenkin's solution, (2) Tomasi's solution, and (3) NaCl solution, have been monitored using electrochemical noise (ECN) analysis and signal processing techniques. The ECN data has been analyzed in time and frequency domains, and the time-domain analysis was used to calculate parameters such as skewness, kurtosis and noise resistance, R_n. The corrosion mechanisms were analyzed in terms of the ranges of skewness and kurtosis. The frequency analysis showed that the conventional fast Fourier transforms (FFT) method failed to differentiate among the ECN signals obtained in different solutions with and without the attachment of bacteria. Therefore, the fractional Fourier transform (FrFT) was introduced to process ECN signals and has been demonstrated as a better tool to describe the corrosion behaviors of electrodes in different solutions.     

X‐ray diffraction (XRD)‐studies on the temperature dependent interface reactions on hafnium,zirconium, and nickel coated monocrystalline diamonds used in grinding segments for stone and concrete machining

Diamond impregnated metal matrix composites are the state of the art solution for the machining of mineral materials. The type of interface reactions between the metal matrix and diamond surface has an essential influence on the tool performance and durability. To improve the diamond retention, the diamonds can be coated by physical vapour deposition with metallic materials, which enforce interface reactions. Hence, this paper focuses on the investigation of the interfacial area on metal‐coated monocrystalline diamonds. Hafnium and zirconium, both known as carbide forming elements, are used as coating materials. The third coating, which is used to determine its catalytic influences when applied as a physical vapour deposition (PVD)‐layer, is nickel. Additionally, the coated diamond samples were heat‐treated to investigate the starting point of the formation of new phases. X‐ray diffraction‐analyses revealed the assumed carbide formation on hafnium and zirconium coated samples. The formation temperature was identified between 800 °C and 1000 °C for hafnium and zirconium coatings.     

Behaviour of huminite macerals from Victorian brown coal in tetralin in autoclaves at temperatures of 300–380 °C

The behaviour of various huminite macerals and submacerals in a hydrogen-donor solvent, tetralin, at high temperature under hydrogen pressure was investigated. Small granular samples of three Victorian brown coals of different lithotype were treated with tetralin in two types of autoclave, at temperatures of 300–380 °C and under pressures of 5 or 10 MPa. The residual materials were investigated microscopically. This tetralin treatment caused huminite macerals and submacerals derived from highly gelified cellular material to become plastic even at temperatures as low as 340 °C, whereas it had no such effect on those derived from ungelified material. This relation between the degree of gelification and the tendency to become plastic during tetralin treatment in an autoclave is very similar to that found for vitrinite macerals and submacerals from bituminous coals.     

Valorization of fatty acid waste for bioplastics production using Bacillus tequilensis: Integration with dark-fermentative hydrogen production process

Synthesis of bioplastics (polyhydroxyalkanoates (PHA)) using Bacillus tequilensis, a newly isolated strain was investigated under aerobic condition using designed wastewater with synthetic acids (SA) and acidogenic fermented food waste (AFW) collected from biohydrogen (H₂) producing anaerobic bioreactors as substrates. The isolate showed the ability to grow and accumulate PHA in both the substrates, with simultaneous waste remediation. Higher PHA synthesis was observed with SA (59% dry cell weight) compared to AFW (36% dry cell weight) with good substrate removal (SA, 87%; AFW, 59%). The PHA composition showed presence of co-polymer [P(3HB-co-3HV)] with varying contents of hydroxy butyrate (HB, 80–90%) and hydroxy valerate (HV, 10–15%) in both the substrates. High dehydrogenase activity was observed which leads to the formation of considerable quantity of PHA. AFW from H₂ producing reactor as substrate contributes in reducing the production cost of both H₂ as well as PHA embedded with waste valorization.     

Thermodynamic study on glycerol-fuelled intermediate-temperature solid oxide fuel cells (IT-SOFCs) with different electrolytes

In this paper, a thermodynamic analysis was carried out to provide useful information about the operation of intermediate-temperature Solid Oxide Fuel Cells (IT-SOFCs) with direct internal reforming (DIR) fuelled by glycerol. A methodology, based on the principle of minimizing the Gibbs energy of a given system, using spreadsheets and the Microsoft Excel’s Solver function, was described for DIR operation of the SOFC with oxygen ion conducting electrolyte (SOFC-O²⁻) and proton conducting electrolyte (SOFC-H⁺). The effect of temperature, fuel utilization and type of electrolyte on the equilibrium composition of the anode gas mixture as well as on the boundary of carbon formation has been investigated in the temperature range of 773–1073 K. Based on the results of this thermodynamic study, glycerol can be considered an alternative fuel with suitable characteristics for electricity generation in IT-SOFCs. Operating at carbon-free conditions, between 773 and 1073 K, with a fuel utilization of 99.99% in the anode channel outlet, glycerol-fuelled IT-SOFCs systems attain high theoretical efficiencies in the range of 80.7–89.9% (SOFC-O²⁻ case) and 90.3–96.7% (SOFC-H⁺ case). Regarding the maximum values of the average electromotive force (EMF) and efficiency, it was verified that glycerol exhibits very similar potential for power generation with ethanol. Although glycerol fed SOFC-H⁺ is superior to SOFC-O²⁻ in terms of maximum theoretical efficiency, it should be taken into account that the SOFC-H⁺ shows a greater tendency for carbon deposition than does the SOFC-O²⁻ during the operation. Besides, it was found that decreasing temperature increases the efficiency but also favors carbon formation, for both SOFC-O²⁻ and SOFC-H⁺. When the system runs at 70% of its maximum power and the partial pressure of residual hydrogen in the anode outlet is kept equal to 0.1 atm, the highest efficiency (67%) is achieved by operating an SOFC-H⁺ at 823 K.     

Reaction chemistry of gossypol and its derivatives

Gossypol, a complex polyphenolic compound, is a naturally occurring highly colored yellow pigment found in the small intercellular pigment glands in the leaves, stems, roots, and seed of cotton plants. In cottonseed, gossypol contributes to its toxicity and therefore it is regarded as an unwanted processing component. It was not until its antitumor and male infertility activities were discovered that gossypol was considered as a valueadded natural product from cottonseed with useful physiological and chemical properties. These serendipitous discoveries created much excitement, and an enormous amount of research on gossypol has ensued. Since then, much research has focused on the preparation of suitable gossypol derivatives for medicinal applications. This review summarizes current knowledge about gossypol, its stereochemistry, tautomerism, and the many varied reactions the gossypol molecule can undergo.     

Electrochemical aspects of new materials and technologies in microelectronics

Major scaling issues, which need to be addressed to continue scaling according to Moore’s law, include increase of transistor leakage due to use of thin gate oxide (about 1 nm limit for SiO₂), power (reaching 100 W/cm²) and RC delay (dielectric constant limit is 1 for air and Cu resistivity increases with scaling down the feature sizes). Integration of new materials and technologies will allow us to continue scaling and improve device performance. Examples of new materials include high-k dielectrics and strained silicon in the frond end of wafer processing, low-k carbon-doped oxide and electroplated copper in the back end of wafer processing as well as electroplated bumps, high thermal conductivity interface, heat sink and heat spreader materials in packaging. Electrochemical technologies will play an increasingly important role in silicon technology due to low cost, use of self-assembly processing and self-aligned growth ability. New electrochemical technologies in silicon processing include copper electroplating (replaced Al interconnect to reduce RC delay and increase reliability), bump electroplating (replaced wire bonding to allow increased I/O and improve reliability), and porous silicon for silicon on isolator fabrication (to reduce transistor leakage). Copper electroplating allows a low R, an excellent gap fill capability and superior materials properties with (111) textured Cu films and large grain size, and a stable and controlled process.     

电弧喷涂金属层电化学性能研究

本文采用电化学测试方法,分析比对电弧喷涂涂层的腐蚀电位、腐蚀电流,进而比较它们对基体金属的牺牲阳极保护作用及腐蚀性能,以期为钢结构长效防腐复合涂层体系的设计提供参考。     

Hybrid Polyoxometalates: Merging Organic and Inorganic Domains for Enhanced Catalysis and Energy Applications

Organic–inorganic hybrids based on polyoxometalate scaffolds(POMs) are a unique class of molecular metal-oxides featuring a composite surface, whereby the merging of complementary domains stimulates new functions and enhances performances. The interaction between the organic and inorganic components can be designed via covalent and/or non-covalent strategies, yielding novel molecular systems with key applications in catalysis and materials science. Selected examples of such a rewarding approach will be illustrated, including the synthesis of tailored POM-based catalysts, and their application in homogeneous systems and on electrocatalytic surfaces for water splitting and renewable energy production.     

离子束溅射制备Pt/C催化电极材料的结构和电化学性能

采用离子束溅射技术制Ｐｔ／Ｃ催化电极,降低了电极耗铂量至０．１９ｍｇ／ｃｍ＾２,电极具有良好的电化学性能。研究了在不同碳质载体材料上用不同沉积条件制备的Ｐｔ／Ｃ电极的电化学性能。