Influence of Soaking Time on Deep Cryogenic Treatment of CuCoNiBe Alloy

Deep cryogenic treatment (DCT) was investigated at different soaking times to determine the microstructural transformation and mechanical properties of copper beryllium (CuCoNiBe) alloy. Lattice shrinkage/distortion resulting from differences in thermal contraction/expansion between the alpha phase and gamma phase caused internal stress, with large atomic dislocations leading to the formation of beryllides. Average beryllide size decreased with increasing DCT time by a maximum of 37% compared to non-DCT because new small beryllides were formed. Beryllides increased and distributed in the ⍺ phase with longer soaking time. Highest beryllide number and volume fraction found at the longest soaking time of 72 h were approximately 200% and 5%, respectively higher than for non-DCT. Increasing the number of beryllides played an important role in enhancing hardness and wear resistance. Maximal increase in hardness at 12% was observed for 72 h DCT, with reduction in wear volume of 30%. Residual stress as compressive stress showed high variation, with uneven distribution over the DCT sample. Impact strength of the DCT samples decreased by 50%. Analysis of fracture surfaces suggested that beryllide shape and beryllide at the grain boundaries played important roles in reducing fracture resistance. Thermal conductivity measurements of DCT-12 h and DCT-72 h samples indicated microstructural change, with the DCT-72 h sample recording a 2% drop in thermal conductivity compared to non-DCT

Experimental Study of Wear Performance of Tool Steel Undergone DUPLEX Surface Treatments for Hot Forging Applications

In recent years, the DUPLEX surface treatment, consisting of vacuum gas nitride followed by physical vapor deposition (PVD) coating, has earn a lot of interest for enhance the wear performance of high temperature forming application, especially hot forging. In this work the wear performance of hot forging tool steel grade AISI H13 undergone DUPLEX treatments with different top coating have been investigated. Three types of PVD coatings, e.g. TiAlN, AlCrN and AlCrTiN, were studied. The microstructure, physical and mechanical properties and surface roughness were also investigated. The wear tests were performed using a high temperature pin-on-disc arrangement at the working temperature of the hot forging tool, i.e. 300°C. The experimental results indicate that the wear behavior is strongly influenced by the level of contact stress developed at the surface. At low contact stress, harder coating shows the better wear performance while, at high contact stress, the tougher coating serves better. Examination of worn surface suggests that this might be caused by change in failure mechanism from ductile fracture to a more brittle manner at high contact stress for hard material. The understanding of the influence of working conditions and coating properties on the wear resistance of tool steels obtained from this work can be very useful in the improvement of wear performance in hot-forging tools and also other high temperature applications

Validity, reliability and interpretability of the Thai version of the urticaria control test (UCT)

Background The Long Form and Short Form of the German (original) version of the Urticaria Control Test (UCT) have shown to be valid and reliable instruments for assessing patients with all types of chronic urticaria (CU). The cutoff scores for identifying patients with well-controlled disease were ≥ 24 and ≥ 12 for Long and Short Forms, respectively. However, the sensitivity to change and minimal clinically important difference (MCID) of the UCT have never been systematically evaluated. This study aimed to investigate the validity, reliability, screening accuracy, sensitivity to change and MCID of the linguistically validated translation of the UCT into the Thai language for assessing CU in the Thai population. Methods A structured translation and pre- testing were done to cross-culturally adapt the UCT for the Thai language. All measurement properties of both forms of the Thai UCT were validated in 169 patients with CU. Results There were strong correlations between the Thai UCT score and disease activity, health-related quality of life impairment, and disease control (all correlations ≥ 0.7). Good internal consistency and excellent intra-rater reliability were demonstrated. The same cutoff scores to define patients with well-controlled disease should be used as those recommended for the original UCT version. MCIDs equated to increase in scores of 6 and 3 for the Long and Short Forms, respectively, of the Thai UCT should be used to identify patients who had minimal responses. Score increments of ≥10 and ≥ 6 for Long and Short Forms, respectively, should be used to define patients who had marked responses. Conclusions This study confirmed the applicability of the UCT for use in Thailand, a country that has a very different language and cultural setting than that of Germany and the United States. Further studies are required to examine the suitability of the UCT for use in the pediatric population

The Thai variant and the distribution of alleles of 6-phosphogluconate dehydrogenase and the distribution of glucose 6-phosphate dehydrogenase deficiency in Thailand

The samples were taken from 3185 subjects from ten provinces throughout Thailand. In 1577 males the frequency of glucose 6-phosphate dehydrogenase deficiency was 11.98%. In the far south the gene frequency was 2.83%; in the remainder of the country the frequency did not vary significantly about a mean of 13.76%. The deficiency is of a severe type. The G6PD of all of the nondeficient individuals had the electrophoretic mobility of type B. The mean frequency of the A/B electrophoretic phenotype of 6-phosphogluconate dehydrogenase is 8.47%. The maximum frequency was in central and southern Thailand with a decline to the north and northeast. A variant form of 6-PGD, referred to as the Thai variant, has been found in which two additional electrophoretic components migrate anodally to the normal A band, confirming that the molecule is at least a dimer. The hypothesis is advanced that erythrocyte 6-PGD is determined by two genetic loci, only one of which is translated in leukocytes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44140/1/10528_2005_Article_BF01474765.pd