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The mechanical behavior of as-cast ZA-27 alloy and hybrid composite reinforced with graphite (Gr) of constant 3% by weight and silicon carbide particle (SiCp) varying from 0-9% by weight in steps of 3% was carried out. Vortex method of production was employed in which thoroughly mixed Gr and SiC particles were poured into the vortex created by means of mechanical stirrer. The melt was cast using a pre-heated permanent mold box. Microstructure showed fine distribution of the reinforcements in the specimen. Tensile and hardness tests were carried out as per ASTM standards. The results reveal that, as the percentage of SiCp was increased, UTS and hardness increased with reduction in ductility.

Muhammad Kohailan,1 Mohammad Alanazi,1 Mahmoud Rouabhia,2 Abdullah Alamri,1 Narasimha Reddy Parine,1 Abdullah Alhadheq,1 Santhosh Basavarajappa,3 Abdul Aziz Abdullah Al-Kheraif,3 Abdelhabib Semlali1 1Genome Research Chair, Department of Biochemistry, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; 2Département de Stomatologie, Faculté de Médecine Dentaire, Groupe de Recherche en Écologie Buccale, Université Laval, Québec City, QC, Canada; 3Dental Biomaterial Research Chair, Department of Dental Health, College of Applied Medical Sciences, King Saud University, Riyadh, Kingdom of Saudi Arabia Background: Cigarette smoking is a major risk factor for lung cancer, asthma, and oral cancer, and is central to the altered innate immune responsiveness to infection. Many hypotheses have provided evidence that cigarette smoking induces more genetic changes in genes involved in the development of many cigarette-related diseases. This alteration may be from single-nucleotide polymorphisms (SNPs) in innate immunity genes, especially the toll-like receptors (TLRs).Objective: In this study, the genotype frequencies of TLR2 and TLR6 in smoking and nonsmoking population were examined.Methods: Saliva samples were collected from 177 smokers and 126 nonsmokers. The SNPs used were rs3804100 (1350 T/C, Ser450Ser) and rs3804099 (597 T/C, Asn199Asn) for TLR2 and rs3796508 (979 G/A, Val327Met) and rs5743810 (745 T/C, Ser249Pro) for TLR6.Results: Results showed that TLR2 rs3804100 has a significant effect in short-term smokers (OR =2.63; P=0.04), and this effect is not observed in long-term smokers (>5 years of smoking). Therefore, this early mutation may be repaired by the DNA repair system. For TLR2 rs3804099, the variation in genotype frequencies between the smokers and control patients was due to a late mutation, and its protective role appears only in long-term smokers (OR =0.40, P=0.018). In TLR6 rs5743810, the TT genotype is significantly higher in smokers than in nonsmokers (OR =6.90). The effect of this SNP is observed in long-term smokers, regardless of the smoking regime per day.Conclusion: TLR2 (rs3804100 and rs3804099) and TLR6 (rs5743810) can be used as a potential index in the diagnosis and prevention of more diseases caused by smoking. Keywords: polymorphism, toll-like receptor, genotyping, smoking, TLR2, TLR6

Brake pads are vital parts of automobiles, where tribological properties are prime concern. Usually, asbestos brake pads were used, which were replaced by copper-based in later years. As brake lining materials have evolved, synthetic friction composites were explored as alternatives. Recent works suggest that, natural composites are promising friction material. However, poor thermal conductivity and frictional stability have limited their applications. Surface treatment of fibers and addition of secondary fillers have improved their possibilities. Thus, hybridization of reinforcements has expanded their range of applications. The present article attempts to review various aspects of brake pads and their testing with attention on natural composites. Their properties were studied to conform their ability to meet desired requirements. The article reviews the studies conducted in recent years on various materials properties related to brake pads. The future potential of natural components in the development of friction composite materials for automotive applications is highlighted. [ABSTRACT FROM AUTHOR]

Hot wire Gas Tungsten Arc Welding (GTAW) process is selected for the fabrication of thick section modified 9Cr 1Mo steel components of Steam Generators (SGs) for 500MWe Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, India. During the welding procedure qualification for fabrication of SGs, the 30 mm and 62 mm thick modified 9Cr 1Mo steel welds were subjected to chemical analysis, visual examination, liquid penetrant examination, radiography examination, micro-hardness tests, longitudinal and transverse tensile tests (at ambient temperature and 525 °C), bend tests, drop weight tests and impact tests (at 0 °C and +18 °C). Literature reveals both positive and negative view on the welding of thick-section steel components. Limited information is available in the open literature on the effect of thickness on material properties of modified 9Cr 1Mo steel welds made by the hot wire GTAW method. In view of the above, authors attempted to systematically investigate the influence of thickness on the mechanical properties of modified 9Cr 1Mo steel welds made by the hot wire GTAW process. In this paper, the chemical compositions, hardness, tensile strength, bending strength and impact properties of 30 mm and 62 mm thick welds produced by narrow gap hot wire GTAW process are characterized and compared. It is found that the mechanical properties of 30 mm and 62 mm thick welds are comparable except the impact properties at 0 °C. The impact strength at 0 °C for a 62 mm thick weld was found inferior in comparison with a 30 mm thick weld. [ABSTRACT FROM AUTHOR]

Digital image processing (DIP) becomes a common tool for analyzing engineering problems by fast, frequent and noncontact method of identification and measurement. An attempt has been made in the present investigation to use this method for automatically detecting the worn regions on the material surface and also its measurement. Brass material has been used for experimentation as it is used generally as a bearing material. A pin on disc dry sliding wear testing machine has been used for conducting the experiments by applying loads from 10 N to 50 N and by keeping sliding distance and sliding speed constant. After testing, images are acquired by using 1/2 inch interline transfer CCD image sensor with 795(H) ∗ 896(V) spatial resolution of 8.6 μ m (H) ∗ 8.3 μ m (V) unit cell. Denoising has been done to remove any possible noise followed by contrast stretching to enhance image for wear region extraction. Segmentation tool was used to divide the worn and unworn regions by identifying white regions greater than a threshold value with an objective of quantifying the worn surface for tested specimen. Canny edge detection and granulometry techniques have been used to quantify the wear region. The results revel that the specific wear rate increases with increase in applied load, at constant sliding speed and sliding distance. Similarly, the area of worn region as identified by DIP also increased from 42.7% to 69.97%. This is because of formation of deeper groves in the worn material. [ABSTRACT FROM AUTHOR]