FEM-based study of precision hard turning of stainless steel 316L

This study aims to investigate chip formation and surface generation during the precision turning of stainless steel 316L samples. A Finite Element Method (FEM) was used to simulate the chipping process of the stainless steel but with only a restricted number of process parameters. A set of turning tests was carried out using tungsten carbide tools under similar cutting conditions to validate the results obtained from the FEM for the chipping process and at the same time to experimentally examine the generated surface roughness. These results helped in the analysis and understanding the chip formation process and the surface generation phenomena during the cutting process, especially on micro scale. Good agreement between experiments and FEM results was found, which confirmed that the cutting process was accurately simulated by the FEM and allowed the identification of the optimum process parameters to ensure high performance. Results obtained from the simulation revealed that, an applied feed equals to 0.75 of edge radius of new cutting tool is the optimal cutting conditions for stainless steel 316L. Moreover, the experimental results demonstrated that in contrast to conventional turning processes, a nonlinear relationship was found between the feed rate and obtainable surface roughness, with a minimum surface roughness obtained when the feed rate laid between 0.75 and 1.25 times the original cutting edge radius, for new and worn tools, respectively

Precision hard turning of ti6al4v using polycrystalline diamond inserts: Surface quality, cutting temperature and productivity in conventional and high-speed machining

This article presents the results of an experimental investigation into the machinability of Ti6Al4V alloy during hard turning, including both conventional and high-speed machining, using polycrystalline diamond (PCD) inserts. A central composite design of experiment procedure was followed to examine the efects of variable process parameters; feed rate, cutting speed and depth of cut (each at five levels) and their interaction efects on surface roughness and cutting temperature as process responses. The results revealed that cutting temperature increased with increasing cutting speed and decreasing feed rate in both conventional and high-speed machining. It was found that high speed machining showed an average increase in cutting temperature of 65% compared with conventional machining. Nevertheless, high speed machining showed better performance in terms of lower surface roughness despite using higher feed rates compared to conventional machining. High-speed machining of Ti6Al4V showed an improvement in surface roughness of 11% compared with conventional machining, with a 207% increase in metal removal rate (MRR) which offered the opportunity to increase productivity. Finally, an inverse relationship was verified between generated cutting temperature and surface roughness. This was attributed mainly to the high cutting temperature generated, softening, and decreasing strength of the material in the vicinity of the cutting zone which in turn enabled smoother machining and reduced surface roughness

A Computerized Tomographic Data Analysis System to Evaluate the Dental Implant Surface Roughness

AbstractDental implants have been progressively used in the recent years to support and retain dental prosthesis. Implant surface roughness has been suggested as a crucial factor in implant osseointegration and long term survival of the implant and prosthesis, where a key factor for the success or failure of dental implants is the manner in which stresses are transferred to surrounding bone. In this study completely edentulous patients were rehabilitated by implant retained over denture in which two implant systems with different surface roughness were used. Peri implant bone density in Hounsfield Units (HU) was evaluated by analyze Computerized Tomographic (CT) images to judge the behavior of an implant system under functional loading, where DICOM raw data was imported into the analysis proposed system to correlate the bone density regarding to the HU values. Results are compared with clinical readings and previous findings, which it showed that there is a difference in peri implant bone density around regularly patterned and randomly patterned implant surfaces

Fuzzy modeling and parameters optimization for the enhancement of biodiesel production from waste frying oil over montmorillonite clay K-30

Transesterification is a promising technology for the biodiesel production to provide an alternative fuel that considers the environmental concerns. From the economic and environmental protection points of view, utilization of waste frying oil for the production of biodiesel addresses very beneficial impacts. Production of higher yield of biodiesel is a challenging process in order to commercialize it with a lower cost. The current study focuses on the influence of different parameters such as reaction temperature (°C), reaction period (min), oil to methanol ratio and amount of catalyst (wt%) on the production of biodiesel. The main objective of this work is to develop a model via fuzzy logic approach in order to maximize the biodiesel produced from waste frying oil using montmorillonite Clay K-30 as a catalyst. The optimization for the operating parameters has been performed via particle swarm optimization (PSO) approach. During the optimization process, the decision variables were represented by four different operating parameters: temperature (40–140 °C), reaction period (60–300 min), oil/methanol ratio (1:6–1:18) and amount of catalyst (1–5 wt%). The model has been validated with the experimental data and compared with the optimal results reported based on other optimization techniques. Results showed the increment of biodiesel production by 15% using the proposed strategy compared to the earlier study. The obtained biodiesel production yield reached 93.70% with the optimal parameters for a temperature at 69.66 °C, a reaction period of 300 min, oil/methanol ratio of 1:9 and an amount of catalyst of 5 wt%

Focused molecular analysis of small cell lung cancer: feasibility in routine clinical practice

© 2015 Abdelraouf et al.Background: There is an urgent need to identify molecular signatures in small cell lung cancer (SCLC) that may select patients who are likely to respond to molecularly targeted therapies. In this study, we investigate the feasibility of undertaking focused molecular analyses on routine diagnostic biopsies in patients with SCLC. Methods: A series of histopathologically confirmed formalin-fixed, paraffin-embedded SCLC specimens were analysed for epidermal growth factor receptors (EGFR), KRAS, NRAS and BRAF mutations, ALK gene rearrangements and MET amplification. EGFR and KRAS mutation testing was evaluated using real time polymerase chain reaction (RT-PCR cobas®), BRAF and NRAS mutations using multiplex PCR and capillary electrophoresis-single strand conformation analysis, and ALK and MET aberrations with fluorescent in situ hybridization. All genetic aberrations detected were validated independently. Results: A total of 105 patients diagnosed with SCLC between July 1990 and September 2006 were included. 60 (57 %) patients had suitable tumour tissue for molecular testing. 25 patients were successfully evaluated for all six pre-defined molecular aberrations. Eleven patients failed all molecular analysis. No mutations in EGFR, KRAS and NRAS were detected, and no ALK gene rearrangements or MET gene amplifications were identified. A V600E substitution in BRAF was detected in a Caucasian male smoker diagnosed with SCLC with squamoid and glandular features. Conclusion: The paucity of patients with sufficient tumour tissue, quality of DNA extracted and low frequency of aberrations detected indicate that alternative molecular characterisation approaches are necessary, such as the use of circulating plasma DNA in patients with SCLC

Effect of Horizontal DNA Transfer in Azospirillum and Azotobacter Strains on Biological and Biochemical Traits of Non-legume Plants

Abstract: Auxin production by Azospirillum and Azotobacter is believed to play a major role on promoting plant growth. Non legume plants inoculated with different genetically modified strains is significantly stimulated due to the contribution of Auxin biosynthesis by Azospirillum transconjugants affecting on root fresh weight of sugar beet above the plants fertilized with 50% of recommended dose. This study focuses the association between 2,4-D and Azospirillum which revealed significant increase in leaf area of top variety at the presence of 2,4-D above the plants fertilized with nitrogen recommended dose. At the absence of 2,4-D some of transconjugants significantly stimulate the leaf area of top variety above the plants fertilized with 50% of nitrogen recommended dose. The importance of horizontal gene transfer is an adaptive mechanism for bacteria, which may result in increased genetic variation by bringing together DNA from different genetic backgrounds. Furthermore, Azospirillum transconjugants (extra copy of DNA) were evaluated in field trail. Together, these results confirm the important role of IAA produced by transconjugants on stimulating root weight and illustrate the power of combining genetic tools and bioassays to elucidate the mechanism of a beneficial Azospirillum -plant interaction. The effects of biofertilizing by Azospirillum transconjugants on the technological parameters of sugar beet were studied. The better results were gained at variety Top (sugar %, potassium, sodium, quality) at the absence of 2,4-D under the effect of biofertilization, but variety dispery obtained better results of alphaamino-nitrogen under the effect of nitrogen recommended dose. When plant-growth promoting rhizobacteria (Azotobacter strains) were used as inoculants for biofertilization and phytostimulation of canola, some of the inoculants improving growth and yield parametres; leaf area, plant height, root dry weight and grain yield/plant above the plants fertilized with 50% of nitrogen recommended dose. In addition, chlorophyll b and grain yield/plant in Serw 6 variety was significantly affected by the addition of 2,4-D. Corn plants biofertilized with Azospirillum strains and their transconjugants appeared significant effect on ear length, plant height, grain content of carotene and leave content of cholorophyll pigments. This work describes the beneficial effect of genetic variations in rhizobacterium strains, which contains an active biological containment system affecting on their effectiveness of nitrogen fixation and auxin production. This leading to recommend to inoculate non -legume plants with selected rhizobacterial isolates to exhibit stimulatory effect on grain yield and root fresh weight (sugar beet). However, plantresponse was varied, due to plant varieties and genetic constitution of rhizobacterial strains as shown in this study. Field experiments conducted in this study on two varieties of sugar beet, canola and corn demonstrated an increase in root fresh and/or dry weight, shoot dry weight and grain yield of inoculated seedlings, above that in the plants fertilized with 50% of nitrogen recommended dose. Colonization of the non-legume plants by rhizobacteria have indirect and direct effects on plant growth and their developments. Direct effects include enhanced provision of nutrients and the production of phytohormones. Indirect effects involve aspects of biological control: the production of antibiotics and the induction of plant resistance mechanisms. It was concluded that the highest auxins-producing strains also caused a maximum increase of growth and yield of non-legume plants

Metabolic Syndrome and Cardiovascular Risk Factors in Obese Adolescent

BACKGROUND: Childhood and adolescent obesity is associated with insulin resistance, abnormal glucose metabolism, hypertension, dyslipidemia, inflammation, liver disease, and compromised vascular function. The purpose of this study was to determine the prevalence of cardiovascular risk factor abnormalities and metabolic syndrome in a sample of obese adolescent as prevalence data might be helpful in improving engagement with obesity treatment in future. The high blood lipid levels and obesity are the main risk factors for cardio vascular diseases. Atherosclerotic process begins in childhood.AIM: This study aimed to investigate the relationship between obesity in adolescent and their blood lipids levels and blood glucose level.METHODS: This study was conducted with 100 adolescents of both gender age 12-17 years and body mass index (BMI) greater than 95th percentiles and 100 normal adolescents as control group. The blood samples were collected from all adolescents after overnight fasting (10 hours) to analyze blood lipids (Total cholesterol, high density lipoprotein, low density lipoprotein) and hematological profile (Hemoglobin, platelets and red blood cell, C reactive protein and fasting blood glucose.RESULTS: There were statistical difference between the two groups for red blood cells (P<0.001), Hemoglobin (P < 0.001) and platelets (P = 0.002), CRP (P = 0.02). Positive correlation was found between the two groups as regards total cholesterol (P = 0.0001), P value was positive for HDL (P = 0.005 and Atherogenic index P value was positive (P = 0.002). Positive correlation was found between the two group as regards fasting blood glucose (P = 0.001).CONCLUSION:  Saturated fat was associated with elevated lipid levels in obese children. These results reinforce the importance of healthy dietary habits since child-hood in order to reduce the risks of cardiovascular diseases in adulthood