Optimization and analysis of dry sliding wear behaviour of N-B4C/MOS2 unreinforced AA2219 nano hybrid composites using response surface methodology

The effect of heat treatment on nano-size B4C particle reinforced hybrid composites is discussed in this paper. For this, hybrid reinforced AA2219 composites with 2% by weight nano B4C and 2% by weight MoS2 particulates were fabricated using a two-stage stir casting process, and the specimens were heat treated to assess their influence on wear behavior. Experiments were carried out to study the wear behavior by varying important factors such as aging temperature, load, and sliding distance. Response Surface Methodology (RSM) designed by Box-Behnken was used to identify the critical variables influencing wear rate and optimize wear behavior. To comprehend the wear mechanisms involved, an analysis of the worn surface was presented. Based on the analysis, a regression equation with a predictability of 97.2% was developed for the response to obtain the optimum wear rate. The following order effectively captures the relative importance of the various factors determining the alloy's wear resistance: sliding distance, load, and aging temperature. When compared to load and sliding distance, heat treatments via artificial aging in the temperature range of 200-240 °C have no significant effect on the wear resistance of hybrid AA2219 composites reinforced with n-B4C and MoS2 particulates. However, when a temperature range of 200-240 °C is considered, composites exhibit better wear resistance at the aging temperature of 240 °C with ice quenching

Study on fracture behaviour of Hybrid Aluminium Composite

This work makes an attempt to study of fracture behaviour of hybrid Composite reinforced with hard ceramic Boron carbide as primary phase and secondary phase as soft solid lubricant Molybdenum Disulphide with base matrix Al2219 by two stage stir casting method is incorporated. Compact tension type specimen was utilized for test and dimensions are conformity to ASTM E-647.Fatigue crack growth and fracture toughness test conducted as per ASTM Standard E-399 and E-1820. This study discloses that reinforcing the hard ceramic Boron Carbide of constant 3wt% and soft solid lubricant Molybdenum Disulphide with increasing wt% of 3%, 4%, 5% to Al2219, results increase in energy required to open the crack front to create two new crack surfaces during mode-I type failure and also significantly variation of fracture toughness. Surface of fractured specimens were study under scanning electron microscope and observes that pulled regions tiny dimples results in balance between ductility and strength of prepared hybrid composite

Study on fracture behaviour of Hybrid Aluminium Composite

This work makes an attempt to study of fracture behaviour of hybrid Composite reinforced with hard ceramic Boron carbide as primary phase and secondary phase as soft solid lubricant Molybdenum Disulphide with base matrix Al2219 by two stage stir casting method is incorporated. Compact tension type specimen was utilized for test and dimensions are conformity to ASTM E-647.Fatigue crack growth and fracture toughness test conducted as per ASTM Standard E-399 and E-1820. This study discloses that reinforcing the hard ceramic Boron Carbide of constant 3wt% and soft solid lubricant Molybdenum Disulphide with increasing wt% of 3%, 4%, 5% to Al2219, results increase in energy required to open the crack front to create two new crack surfaces during mode-I type failure and also significantly variation of fracture toughness. Surface of fractured specimens were study under scanning electron microscope and observes that pulled regions tiny dimples results in balance between ductility and strength of prepared hybrid composite

Impact of dengue fever on liver function tests and to relate liver function tests with severity of disease

Introduction: Dengue fever is an ancient disease. The earliest record found today is in a Chinese encyclopedia of disease symptoms and remedies, first published during Chin dynasty (265 to 420 AD). Severe Dengue was first recognized in the 1950s during dengue epidemics in the Philippines & Thailand,.has become a leading cause of hospitalization and death among children in these regions1.Liver dysfunction as a result of dengue infection can be a direct viral effect on liver cells or an adverse consequence of dysregulated host immune response against the virus. Material and methods: Hospital based prospective observational study conducted at Sri Venketeswara Ram Naraian Ruia Government General Hospital; Tirupati included all NS1 Ag positive or dengue Ig M positive cases in the age group of 6 months to 12 years.              Results: Liver function tests AST, ALT and Alk phosphatase, bilirubin were deranged in children with severe dengue and dengue with warning signs compared to dengue without warning signs. Total bilirubin, AST, ALT and alkaline phophatase derangements were highly significant with p-value0.001. Enzymes are elevated significantly in severe dengue compared to dengue with and without warning signs Conclusion: All the liver function tests (Total bilirubin, AST, ALT and Alk phosphatase) were higher in children with severe dengue compared to dengue fever with warning signs and dengue fever without warning signs .The mean AST and ALT levels were 231.31 and 201.14 U/L respectively. This differs from the pattern in viral hepatitis