Formation of zinc phosphate coating by anodic electrochemical treatment

The formation of zinc phosphate coating by anodic electrochemical treatment is addrsed. The importance of the addition of nitrite, the extent of sludge formation and the eco-friendliness of the process is presented. Based on the amount of coating weight and change in potential–time measurements, a mechanism for the coating formation is proposed. The coating characteristics and corrosion resistance were evaluated. The study reveals that anodic electrochemical treatment, though enabling an acceleration of coating deposition, results in heavy sludge formation, making the process less eco-friendly. The coatings obtained by anodic phosphating are rich in phosphophyllite phase with a smaller proportion of hopeite phase and iron phosphate. Since the porosity of the anodically phosphated mild steel substrate is relatively higher, these coatings will suit applications which require higher oil-retaining capacity. The corrosion behaviour of anodically phosphated mild steel substrate in 3.5% sodium chloride solution reveals the ability of the phosphate coating to act as a barrier film towards the ingress of corrosive media

Formation of zinc–zinc phosphate composite coatings by cathodic electrochemical treatment

The formation of zinc–zinc phosphate composite coatings by cathodic electrochemical treatment and evaluation of its corrosion resistance is addressed in this paper. The cathodic phosphating process offers some unique advantages—it requires no specific addition of accelerator in the bath, it is capable of producing good quality coatings even at low temperature, it permits deposition of coatings of desired thickness, thus offering benefits in terms of energy savings, decrease in processing cost and improvement in plant life. Being a cathodic process, there is no iron dissolution and no ferric phosphate sludge formation, which renders it an eco-friendly process. Based on the amount of coating mass as a function of process variables and the potential-time measurement, a pictorial model is proposed for the deposition of zinc phosphate coating. The surface morphology of the coatings exhibits plate-like crystals. The corrosion behaviour of cathodically phosphated mild steel substrate in 3.5% sodium chloride solution exhibits the stability of these coatings, which last for a week with no red rust formation. This is due to the presence of a composite layer of zinc and zinc phosphate that acts as a mechanical barrier against further corrosion for a considerably longer time. Being a cathodic process, the possibility of hydrogenation of steel is the major limitation of this methodology

Formation and characteristics of zinc phosphate coatings obtained by electrochemical treatment: Cathodic vs. anodic

Electrochemical treatment and galvanic coupling are some of the possible modes of acceleration of low temperature phosphating process. The cathodic and anodic treatments during phosphating influence the deposition mechanism, characteristic properties and the corrosion resistance of the resultant coatings in a differentway. The present paper aims to compare these aspects and to identify the possible applications of phosphate coatings obtained by these treatments

In vitro phosphorylation as tool for modification of silk and keratin fibrous materials

An overview is given of the recent work on in vitro enzymatic phosphorylation of silk fibroin and human hair keratin. Opposing to many chemical "conventional" approaches, enzymatic phosphorylation is in fact a mild reaction and the treatment falls within "green chemistry" approach. Silk and keratin are not phosphorylated in vivo, but in vitro. This enzyme-driven modification is a major technological breakthrough. Harsh chemical chemicals are avoided, and mild conditions make enzymatic phosphorylation a real "green chemistry" approach. The current communication presents a novel approach stating that enzyme phosphorylation may be used as a tool to modify the surface charge of biocompatible materials such as keratin and silk

Current Treatment of Endolymphatic Sac Tumor of the Temporal Bone

An endolymphatic sac tumor (ELST) is a rare, indolent but locally aggressive tumor arising in the posterior petrous ridge. Patients present with sensorineural hearing loss and tinnitus. As the tumor progresses, patients may experience vertigo, ataxia, facial nerve paresis, pain and otorrhea. Most patients present in their 4th or 5th decade with a wide age range. Patients with von Hippel–Lindau disease have an increased likelihood of developing ELST. Histologically, ELST is a low-grade adenocarcinoma. As it progresses, it destroys bone and extends into adjacent tissues. The likelihood of regional or distant metastases is remote. The optimal treatment is resection with negative margins. Patients with positive margins, gross residual disease, or unresectable tumor are treated with radiotherapy or radiosurgery. Late recurrences are common, so long follow-up is necessary to assess efficacy. The likelihood of cure depends on tumor extent and is probably in the range of 50–75%

Characterization of an extracellular lipase and its chaperone from Ralstonia eutropha H16

Lipase enzymes catalyze the reversible hydrolysis of triacylglycerol to fatty acids and glycerol at the lipid–water interface. The metabolically versatile Ralstonia eutropha strain H16 is capable of utilizing various molecules containing long carbon chains such as plant oil, organic acids, or Tween as its sole carbon source for growth. Global gene expression analysis revealed an upregulation of two putative lipase genes during growth on trioleate. Through analysis of growth and activity using strains with gene deletions and complementations, the extracellular lipase (encoded by the lipA gene, locus tag H16_A1322) and lipase-specific chaperone (encoded by the lipB gene, locus tag H16_A1323) produced by R. eutropha H16 was identified. Increase in gene dosage of lipA not only resulted in an increase of the extracellular lipase activity, but also reduced the lag phase during growth on palm oil. LipA is a non-specific lipase that can completely hydrolyze triacylglycerol into its corresponding free fatty acids and glycerol. Although LipA is active over a temperature range from 10 °C to 70 °C, it exhibited optimal activity at 50 °C. While R. eutropha H16 prefers a growth pH of 6.8, its extracellular lipase LipA is most active between pH 7 and 8. Cofactors are not required for lipase activity; however, EDTA and EGTA inhibited LipA activity by 83 %. Metal ions Mg[superscript 2+], Ca[superscript 2+], and Mn[superscript 2+] were found to stimulate LipA activity and relieve chelator inhibition. Certain detergents are found to improve solubility of the lipid substrate or increase lipase-lipid aggregation, as a result SDS and Triton X-100 were able to increase lipase activity by 20 % to 500 %. R. eutropha extracellular LipA activity can be hyper-increased, making the overexpression strain a potential candidate for commercial lipase production or in fermentations using plant oils as the sole carbon source.Malaysia-MIT Biotechnology Partnership Programm