Characterization of a Laser Surface-Treated Martensitic Stainless Steel.

Laser surface treatment was carried out on AISI 416 machinable martensitic stainless steel containing 0.225 wt.% sulfur. Nd:YAG laser with a 2.2-KW continuous wave was used. The aim was to compare the physical and chemical properties achieved by this type of selective surface treatment with those achieved by the conventional treatment. Laser power of different values (700 and 1000 W) with four corresponding different laser scanning speeds (0.5, 1, 2, and 3 m•min-1) was adopted to reach the optimum conditions for impact toughness, wear, and corrosion resistance for laser heat treated (LHT) samples. The 0 °C impact energy of LHT samples indicated higher values compared to the conventionally heat treated (CHT) samples. This was accompanied by the formation of a hard surface layer and a soft interior base metal. Microhardness was studied to determine the variation of hardness values with respect to the depth under the treated surface. The wear resistance at the surface was enhanced considerably. Microstructure examination was characterized using optical and scanning electron microscopes. The corrosion behavior of the LHT samples was also studied and its correlation with the microstructures was determined. The corrosion data was obtained in 3.5% NaCl solution at room temperature by means of a potentiodynamic polarization technique.

Bone turnover markers in Paget's disease of the bone: A Systematic review and meta-analysis.

UNLABELLED: The aim of this systematic review and meta-analysis is to study the utility of the commonly used bone turnover markers in evaluating disease activity in patients with Paget's disease of bone before and after treatment with bisphosphonates. We found good correlation between the bone turnover marker concentrations and disease activity assessed by bone scintigraphy. INTRODUCTION: Paget's disease of bone is a common skeletal disorder of the elderly. Bone turnover marker concentrations are used for diagnosis and follow-up. We aimed to compare the available bone turnover markers and determine their utility in assessing disease activity when compared to quantitative bone scintigraphy. METHODS: We conducted a systematic review and meta-analysis searching MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Scopus. We evaluated total alkaline phosphatase (total ALP), bone-specific alkaline phosphatase (bone ALP), procollagen type 1 amino-terminal propeptide (P1NP), serum, and urine C-terminal telopeptide (uCTx and sCTx, respectively), and urine N-terminal telopeptide (uNTx). The main outcome of interest was the correlation of disease activity with concentrations of bone turnover markers in Paget's disease patients before and after treatment with bisphosphonates. Correlation coefficients were pooled across studies using the random effects model. RESULTS: We included 17 observational studies and one trial reporting on 953 patients. Prior to treatment, all studied bone turnover markers had moderate to strong correlation with scintigraphic indices (correlation coefficients ranging from 0.58 to 0.80) with no statistically significant difference between the bone turnover markers overall (p = 0.08). P1NP, uNTx, and bone ALP tend to have higher correlation with scintigraphy. After starting treatment with bisphosphonate, there was moderate to strong correlation with disease activity with all markers except bone ALP (correlation coefficients ranging from 0.43 to 0.70). CONCLUSION: The findings of this meta-analysis suggest the Paget's disease activity is best monitored by following P1NP levels. However, total ALP, bone ALP, and uNTx are good alternatives as markers of disease activity in untreated patients. Total ALP and uNTx can be useful in following patients with Paget's disease after treatment if P1NP is not available. Clinicians, however, should take availability, cost, and the presence of liver disease into consideration when deciding which bone turnover marker is most appropriate when evaluating patients with Paget's disease.