Process mapping of laser surface modification of AISI 316L stainless steel for biomedical applications

A 1.5-kW CO2 laser in pulsed mode at 3 kHz was used to investigate the effects of varied laser process parameters and resulting morphology of AISI 316L stainless steel. Irradiance and residence time were varied between 7.9 to 23.6 MW/cm2 and 50 to 167 µs respectively. A strong correlation between irradiance, residence time, depth of processing and roughness of processed steel was established. The high depth of altered microstructure and increased roughness were linked to higher levels of both irradiance and residence times. Energy fluence and surface temperature models were used to predict levels of melting occurring on the surface through the analysis of roughness and depth of the region processed. Microstructural images captured by the SEM revealed significant grain structure changes at higher irradiances, but due to increased residence times, limited to the laser in use, the hardness values were not improved

Comparative Study of Iron Supplements in South Indian Antenatal Women with Iron Deficiency Anemia

BACKGROUND: Iron deficiency anemia is the most common nutritional disorder in the world. It is a major public health problem particularly among pregnant women with adverse effects on the mother and the new born. Iron supplementation is universally recommended to correct or prevent iron deficiency. AIMS & OBJECTIVE: The present study was conducted to compare the efficacy and tolerability of three oral iron preparations in anemic pregnant women of more than 14 weeks of gestation. MATERIALS AND METHODS: Randomized Control trial, done at Tagore Medical College and Hospital, Chennai. 60 antenatal women were selected; they were divided into three groups, 20 in each group. They were treated with Carbonyl iron, ferrous sulphate and ferrous fumarate. Hemoglobin estimation was done at 0 day, 30th and 60th day. Adverse effects were monitored. RESULTS: Data analysis showed an increase in haemoglobin levels in all three groups after the 30th day (p<0.05). Carbonyl iron showed highly significant increase (p<0.05) in the haemoglobin level as compared to the other two drugs at the end of the 60th day. CONCLUSION: Carbonyl iron is superior in efficacy when compared to ferrous sulphate and ferrous fumarate and is better tolerated. So carbonyl iron is safe in pregnancy and can be given as a supplement to treat iron deficiency anemia during pregnancy

The effects of cold working on sensitization and intergranular corrosion behavior of AISI 304 stainless steel

The effects of prior cold rolling of up to an 80 pct reduction in thickness on the sensitization-desensitization behavior of Type AISI 304 stainless steel and its susceptibility to intergranular corrosion have been studied by electrochemical potentiokinetic reactivation (EPR) and Strauss-test methods. The results indicate that the prior deformation accelerated the sensitization as compared to the undeformed stainless steel. The deformed Type 304 stainless steel experienced desensitization at higher temperatures and times, and it was found to be enhanced by increased cold deformation. This could be attributed to the increased long-range chromium diffusion, possibly brought on by increasing pipe diffusion and vacancies. The role of the deformation-induced martensite (DIM) and texture, introduced by uniaxial cold rolling, on the sensitization-desensitization kinetics has also been discussed. This study could not reveal any systematic relationship between texture and the degree of sensitization (DOS) obtained. The effect of DIM on DOS seems to be pronounced at 500 °C when the steel retained significant amounts of DIM; however, the retained DIM is insignificant at higher sensitization times and temperatures

Influence of metallurgical variables on sensitisation kinetics in austenitic stainless steels

Austenitic stainless steels are the most favoured construction materials for various components required in chemical, petrochemical, fertiliser and nuclear industries. However, these steels are prone to sensitisation. In the sensitised condition, the steels are quite susceptible to intergranular corrosion and intergranular stress corrosion cracking in chloride and caustic environments resulting in the premature failure of the fabricated components during precommissioning and service periods. The topic of sensitisation has been of interest in studies worldwide. The studies included mechanism of sensitisation, test methods, data generation, and influence of several variables and protection methods. This article covers a review of important contributions to this topic with special emphasis on the influence of metallurgical variables. The present state of understanding is discussed in the following areas: mechanisms, test methods, sensitisation diagrams, influence of chemical composition, cold work and grain size, low temperature sensitisation, modelling and laser surface treatment. The need for further investigation in certain areas is highlighted

Antinociceptive pattern of flavone and its mechanism as tested by formalin assay

182-185Flavone, dextrose and long swim stress exhibited antinociception. Degree of antinociception was greater with long swim stress as compared to flavone or dextrose. Combination of these treatments resulted in potentiation of antinociception. Naloxone (opioid antagonist; 5 mg/kg ip) antagonised flavone or long stress induced antinociception showing opioid mediated mechanism, however, failed to reverse the potentiated antinociceptive component recorded in long stressed animals which received flavone and dextrose. Antinociceptive activity of flavone, dextrose and long swim stress which was documented by acetic acid assay has been confirmed in the present study. Role for opioid system in this action has been demonstrated. Therefore, formalin test can also be considered as an useful assay procedure for testing flavonoids. However, like acetic acid assay this assay procedure also has the limitation that it is unable to detect minor changes in the degree of antinociception produced by physiological interventions such as long swim and dextrose

Modulation by insulin rather than blood glucose of the pain threshold in acute physiological and flavone induced antinociception in mice

1009-1016<span style="font-size: 15.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">The present study investigated the cause effect relationship between glycemic and algesic states. The hypo- and hyperglycemic conditions were induced physiologically through exercise (3 min swim at room temperature 28°-30°C) and external dextrose (2 g/kg, ip) administration respectively in mice. Besides, flavone (50 mg/kg, sc) a known antinociceptive drug was chosen to study such a cause effect relationship. The anti-nociception was assessed by acetic acid assay, blood glucose measured using glucometer (Ames) and serum insulin by radioimmunoassay. The findings revealed that irrespective of the glycemic state whether hypo-, hyper, or euglycemic induced by swim stress, dextrose or flavone <span style="font-size:15.5pt;mso-bidi-font-size:8.5pt;font-family: " times="" new="" roman","serif""="">per se <span style="font-size:15.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">respectively, significant antinociceptive response was recorded. Pretreatment with flavone (50 mglkg, sc) always exhibited a tendency to reverse the hyperglycemia, if any, but enhanced the antinociceptive response either after swim stress or after dextrose. These data support the contention that changes in the glycemic state in acute condition is not responsible for antinociceptive response and thereby suggesting dissociation between these two parameters. Extended studies estimating serum insulin level after the above mentioned maneuvers showed a significant rise whenever antinociceptive response was recorded irrespective of the glycemic state. <span style="font-size:15.5pt;mso-bidi-font-size: 8.5pt;font-family:" arial","sans-serif""="">It <span style="font-size:15.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">is suggested that serum insulin level, a hormonal parameter rather than the blood glucose level, which is a metabolic parameter, appears more reliable. It appears that the changes in serum insulin level produced by various treatments may have a relationship with the antinociceptive response. However, this study has the limitation that the results can apply only for acute conditions and extrapolation to clinical conditions is debatable. </span