Influence of Cr3C2/NiCr Coating on Stainless Steel and Optimization of Mechanical Properties by Thermal Sprayed High Velocity Oxy-Fuel Coatings

The thermal spray coating is one of the surface strengthening techniques are being used in different applications like, hydro turbine blades, automobile engine, aerospace and medical tools etc. Various coating techniques have been utilised to enhance the surface properties of the base material. The aim of this present work is to optimise the High-Velocity Oxy-Fuel (HVOF) spray process parameters such as, LPG flow rate, Oxygen flow rate, powder feed rate and standoff spray distance of Cr3C2-25%NiCr coated stainless steel material through Response Surface Methodology (RSM) method. The metallurgical structural studies have been examined by the Optical Microscope, Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) analyses whereas, surface hardness was determined by the Vickers micro hardness tester. The maximum obtained surface coating hardness is 1258/HV for the corresponding optimized HVOF process parameters the optimised process parameters such as LPG flow rate, Oxygen flow rate, Powder feed rate and Standoff distance are 65.45 lpm, 280 lpm, 40.55 gpm and 220 mm respectively. The maximum enhancement of Vickers micro hardness of Cr3C2-25%NiCr coated stainless steel is 25.85% over uncoated base metal

Air Pollution Tolerance Index (APTI) Assessment in Tree Species of Coimbatore Urban City, Tamil Nadu, India

Aims: Forest restoration in urbanized and polluted cities is paving the way for mitigation of climate change by reducing the air pollutants level and carbon content level in atmosphere. So, the study was conducted at Coimbatore urban city, Tamil Nadu by using twenty five tree species to know their air pollution tolerance index (APTI) level. Study Design: The sample procedure used for assessing the APTI was stratified random sampling. Place and Duration of Study: The leaf sample was collected from different zones of Coimbatore urban city and the sample analysis was carried out in Department of Silviculture, Forest College and Research Institute, Mettupalayam, Tamil Nadu between August 2015-April 2017. Methodology: Five zones namely residential, industrial, commercial, heavy traffic and control zone were identified from Coimbatore city for estimating the air pollution tolerance index (APTI). In order to assess the air pollution tolerance index of tree species, the biochemical parameters like ascorbic acid content, total chlorophyll content, leaf extract pH and relative water content (RWC) were estimated. Results: Among the 25 tree species tested, Thespesia populnea recorded highest APTI of 16.07, 15.76, 14.63 and 14.37 in heavy traffic zone, industrial zone, control zone and residential zone respectively. In commercial zone, Pongamia pinnata accounted highest APTI value of 13.96. On contrary, the lowest level of APTI was registered by Michelia champaca in industrial zone (10.21), Peltophorum pterocarpum in heavy traffic zone (10.93), Spathodea campanulata in residential zone (11.11) and Albizia saman in commercial zone (11.46). Conclusion: On an overall, Thespesia populnea and Pongamia pinnata were performed well with highest APTI and they can be used for controlling the air pollution level in urban cities

Uncoupled nitric oxide synthase activity promotes colorectal cancer progression

Increased levels of reactive oxygen/nitrogen species are one hallmark of chronic inflammation contributing to the activation of pro-inflammatory/proliferative pathways. In the cancers analyzed, the tetrahydrobiopterin:dihydrobiopterin ratio is lower than that of the corresponding normal tissue, leading to an uncoupled nitric oxide synthase activity and increased generation of reactive oxygen/nitrogen species. Previously, we demonstrated that prophylactic treatment with sepiapterin, a salvage pathway precursor of tetrahydrobiopterin, prevents dextran sodium sulfate–induced colitis in mice and associated azoxymethane-induced colorectal cancer. Herein, we report that increasing the tetrahydrobiopterin:dihydrobiopterin ratio and recoupling nitric oxide synthase with sepiapterin in the colon cancer cell lines, HCT116 and HT29, inhibit their proliferation and enhance cell death, in part, by Akt/GSK-3β–mediated downregulation of β-catenin. Therapeutic oral gavage with sepiapterin of mice bearing azoxymethane/dextran sodium sulfate–induced colorectal cancer decreased metabolic uptake of [18F]-fluorodeoxyglucose and enhanced apoptosis nine-fold in these tumors. Immunohistochemical analysis of both mouse and human tissues indicated downregulated expression of key enzymes in tetrahydrobiopterin biosynthesis in the colorectal cancer tumors. Human stage 1 colon tumors exhibited a significant decrease in the expression of quinoid dihydropteridine reductase, a key enzyme involved in recycling tetrahydrobiopterin suggesting a potential mechanism for the reduced tetrahydrobiopterin:dihydrobiopterin ratio in these tumors. In summary, sepiapterin treatment of colorectal cancer cells increases the tetrahydrobiopterin:dihydrobiopterin ratio, recouples nitric oxide synthase, and reduces tumor growth. We conclude that nitric oxide synthase coupling may provide a useful therapeutic target for treating patients with colorectal cancer