Preparation and Characterization of Inorganic Organic Hybrid Material Based on TEOS/MAPTMS for Biomedical Applications

Silicon - In this study, inorganic-organic hybrid material consisting of tetraethyl orthosilicate (TEOS) and 3-methacryloxypropyl trimethoxysilane (MAPTMS) were prepared with sol-gel process and...     

From Natural Methylation to Versatile Alkylations Using Halide Methyltransferases

Halide methyltransferases (HMTs) enable the enzymatic synthesis of S-adenosyl-l -methionine (SAM) from S-adenosyl-l -homocysteine (SAH) and methyl iodide. Characterisation of a range of naturally occurring HMTs and subsequent protein engineering led to HMT variants capable of synthesising ethyl, propyl, and allyl analogues of SAM. Notably, HMTs do not depend on chemical synthesis of methionine analogues, as required by methionine adenosyltransferases (MATs). However, at the moment MATs have a much broader substrate scope than the HMTs. Herein we provide an overview of the discovery and engineering of promiscuous HMTs and how these strategies will pave the way towards a toolbox of HMT variants for versatile chemo- and regioselective biocatalytic alkylations.     

The generation of surface roughness during slurry erosion-corrosion and its effect on the pitting potential

Results of experiments performed to isolate the effect of surface roughness generated during slurry erosion-corrosion of 304L stainless steel are presented. Surfaces prepared by grinding to different finishes show that increasing the roughness lowers the pitting potential in chloride solution. Subsequent erosion by an aqueous sand slurry then alters this pitting potential (E_p), as measured in the solution phase alone, in a manner dependent on the initial surface roughness. Surfaces which were initially rougher show a pronounced rise in _p after erosion, while those with an initially smoother finish show a fall in E_p after erosion. Measurement of E_p during erosion-corrosion does not fit either process, with values of _Ep lower than those predicted from the surface roughness alone.     

Oberflächenbehandlungsverfahren und deren Einfluß auf die Korrosionsbeständigkeit nichtrostender Stähle

Surface treatments and their influence on the corrosion resistance of stainless steel The surface treatments pickling, grinding and glass beading were investigated on several stainless austenitic steels and one ferritic/austenitic steel. The different surface treatments were used on two different prepared types of samples:

• 1 high temperature oxidized samples
• 2 welded samples

The quality of the surface treatments has been examined by means of potentiodynamic, ferric chloride, dip and spray tests made in series. The corrosion resistance was highly depending on the used treatments. All in all the examination showed that a higher corrosion resistance was achieved by pickling than by grinding or glass beading.     

Mechanical and Corrosion Properties of ZrB2–SiC Composite Ceramics with Oxide Additions

Powder Metallurgy and Metal Ceramics - Hot pressing was used to produce compact ceramic samples with the following composition (wt.%): 60 ZrB2 + 20 SiC + 20 (Al2O3 + 32 t-ZrO2). The tetragonal...     

Interaction of Components in Glass-Forming Melts of Iron and Nickel with Titanium,Zirconium, and Hafnium II. Temperature–Concentration Dependence of Thermodynamic Mixing Functions of Liquid Alloys

Powder Metallurgy and Metal Ceramics - The thermodynamic properties of liquid alloys in glass-forming systems were described in the framework of the associated solution model (ASM) according to the...     

Mold-filling characteristics of AZ91 magnesium alloy in the low-pressure expendable pattern casting process

The magnesium (Mg) alloy low-pressure expendable pattern casting (EPC) process is a newly developed casting technique combining the advantages of both EPC and low-pressure casting. In this article, metal filling and the effect of the flow quantity of inert gas on the filling rate in the low-pressure EPC process are investigated. The results showed that the molten Mg alloy filled the mold cavity with a convex front laminar flow and the metal-filling rate increased significantly with increasing flow quantity when flow quantity was below a critical value. However, once the flow quantity exceeded a critical value, the filling rate increased slightly. The influence of the flow quantity of inert gas on melt-filling rate reveals that the mold fill is controlled by flow quantity for a lower filling rate, and, subsequently, controlled by the evaporation of polystyrene and the evaporation products for higher metal velocity. Meanwhile, the experimental results showed that the melt-filling rate significantly affected the flow profile, and the filling procedure for the Mg alloy in the low-pressure EPC process. A slower melt-filling rate could lead to misrun defects, whereas a higher filling rate results in folds, blisters, and porosity. The optimized filling rate with Mg alloy casting is 140 to 170 mm/s in low-pressure EPC.     

Using mineralogy to optimize gold recovery by direct cyanidation

The complete and accurate gold deportments of direct cyanide leach residues provide a clear picture of the occurrence of unrecovered gold and identify causes for poor extraction. Based on the independent measurement of each form and carrier of unleached gold, opportunities for recovery optimization can be assessed more accurately by providing meaningful targets and can help identify the means to achieve such targets. In ten of 14 leach plants surveyed, 23% of the unrecovered gold could be extracted without finer grinding. For more information, contact S. Chryssoulis, AMTEL, 205-100 Collip Circle, London, Ontario, Canada N6G 4X8; (519) 858-5037; fax (519) 858-5038; e-mail amtel@skynet.ca.     

Metallurgical Features of Plasma Surfacing Repair of Magnesium Alloys

Metallurgist - Results are provided for studying formation of the structure and properties of products made of high-strength light alloy ML5 of the magnesium-aluminum-manganese-zinc system using...