Development of Mathematical Model and Characterization of Internal Surface Obtained by Elasto-Abrasives Magneto-Spiral Finishing (EAMSF)

The implantation of stents and instruments with capillary action demands super-finished internal surfaces of the manufactured product. Elasto-abrasives magneto-spiral finishing (EAMSF) is the attempt made in this paper to enhance finishing productivity by incorporating the abrasive flow in spiral motion due to the presence of the magnetic field. Here, novel impregnated elasto-magnetic abrasive particles (IMPs) are used in a magnetic field-assisted environment to polish the inner walls of the workpiece. In EAMSF, magnetic force provides excess finishing pressure to the abrasives. In contrast, the high-impact polystyrene (HIPS) elasticity absorbs the extra force of the IMPs on the finishing surface. An Indigenous mathematical relation considering the physics of this superfinishing process indicating material removal shows a close resemblance to the experimental results with an error percentage of 1.03 has been developed. The results of the experimentation reveal that 50% concentration of abrasives and a magnetic field density of 18mT yield a superior surface finish with a Ra value equal to 0.053 μm and maximum material removal of 6.9 mg, while in the absence of a magnetic field, excellent surface finish with a Ra=0.266 μm and maximum material removal of 5.4 mg is achieved. In the presence of magnetic field density, significant enhancement of material removal, surface finish, and burr removal is observed. Finishing the surface at 50% abrasive concentration with a magnetic field represents regular finishing, and the trench marks on the original surface are removed after finishing

Effectiveness of friction dampers on seismic response of structure considering soil-structure interaction

U ovom se radu analizira utjecaj međudjelovanja konstrukcije i tla (SSI) na sustav s jednim stupnjem slobode, s tarnim prigušivačem i bez njega. Konstrukcija s različitim vrijednostima mase, krutosti i uvjeta tla pripremljena je i analizirana za deset različitih potresa. Na temelju nelinearnog proračuna s vremenskim zapisom, analiziran je odziv konstrukcije s jednim stupnjem slobode pri raznim vrijednostima kliznog opterećenja tarnog prigušivača. Utvrđeno je da parametri tla utječu na ponašanje tarnog prigušivača. Osim toga, uočeno je da se vrijednosti optimalnog kliznog opterećenja i krutosti ukruta mijenjaju ovisno o vrsti tla.The effect of soil structure interaction (SSI) on a single degree of freedom system with and without friction damper is analysed in the paper. The structure with different mass, stiffness and soil conditions was prepared and analysed for ten different earthquake records. Using the non-linear time history analysis, the structural response of a single degree of freedom structure with varying slip load of friction damper was studied. It was observed that the performance of friction dampers is influenced by soil parameters. Also, it was established that an optimum slip load and stiffness of brace changes with respect to the type of soil

Diversity of ornamental trees from Amravati city of West Vidarbha region

The present study deals with the diversity of ornamental trees from Amravati District of West Vidarbha region of Maharashtra. All these ornamental trees show diversity in their habitat, floral structure, flowering period, etc. In the present investigation, extensive field surveys were conducted in the different localities of Amravati district during 2005-2011containing description, distribution, origin, vegetative and flowering period of 25 ornamental trees species from 19 families with their photographs and preserved as Herbaria

Phytochemical screening of some Euphorbiaceae members

The present investigation includes the Phytochemical screening of some medicinally important plants from the family Euphorbiaceae. All the members studied are exotic but naturalized except Ricinnus communis L. which is commercially cultivated in India. Plant extracts were prepared in various solvents and phytochemically they were tested in the solvent where the good extraction or active extraction observed, Phytochemical tests were carried out specially for screening secondary metabolites from the selected exotic medicinal plants from family Euphorbiaceae. Six genera and seven species of Euphorbiaceae were phytochemically analyzed to find secondary metabolites. Â

Electro Discharge Machining Characteristics of Ti-6Al-4V Alloy: A Grey Relational Optimization

AbstractThe paper presents the grey relational theory based parameter optimisation in electro discharge machining (EDM) of Ti-6Al-4V alloy. The multiple responses optimized are material removal rate (MRR), electrode wear rate (EWR) and surface roughness (SR). The process parameters include duty cycle, pulse current, pulse on time, electrode type and gap voltage. Experiments were conducted using Taguchi L18 orthogonal array. From grey relational analysis, the optimum values found are duty cycle (8%), pulse current (18 Amp), pulse on time (200μsec) and voltage (40V). Experimental results revealed that the copper electrode gives the optimum performance in terms of higher MRR and lower EWR and SR. The optimized process parameters that simultaneously leading to a lower electrode wear ratio and higher material removal rate are then verified through a confirmation experiment

Dual Clutch Transmission of Power Train: An Overview

The best possible responses during shifting in dual clutch transmission, it is to integrate clutch and engine control. Clutch is main device which is used to transmit the motion between to co-axial shaft .The application of torque based on power train control for multi-speed of power shifting capable of electrical vehicles and the operation of two clutches during a gear shift process in dual clutch transmission is considered. An optimization lots of problem is created in compact form and energy loss in the clutch are minimized. Torque estimation it gives the response of hydraulic system, also included simulation of poor estimation and finally increased powertrain vibration during and after shifting. It is to reduce shift transients developed in dual clutch transmission of powertrains. This result based on clutch and engine, Signficantly improves powertrain response

Is prenatal screening for Down syndrome needed in young pregnant women?

Background: Down syndrome originally known as Mongoloid’s idiocy is the most common autosomal disorder. Down syndrome (DS) can be detected by prenatal diagnosis which includes the triple marker screening test and chromosomal analysis.Methods: The study population comprised of 100 pregnant females amongst the age group of 20-45 (32.10±4.86) years. Triple Marker Test was done followed by amniocentesis or CVS with karyotyping or FISH.Results: Risk of <1:250 was considered high risk whereas ≥1:250 was considered as low risk. 32/45 (71%) were false-positive for Trisomy 21 detected as high risk by TMT. But there was good sensitivity and specificity for Trisomy 18.Conclusions: It can be concluded that the triple marker test is indeed only a screening test for the DS and that it has to be confirmed with the help of chromosomal analysis. The higher maternal age is an important parameter in DS but nowadays, even ones with a lower maternal age can also have a child with DS. So, in general, now all women are recommended to go for biochemical screening during their pregnancy

Imaging calcification in aortic stenosis

BACKGROUND Aortic stenosis is a common and potentially fatal condition in which fibro-calcific changes within the valve leaflets lead to the obstruction of blood flow. Severe symptomatic stenosis is an indication for aortic valve replacement and timely referral is essential to prevent adverse clinical events. Calcification is believed to represent the central process driving disease progression. 18F-Fluoride positron emission tomography computed tomography (PET-CT) and CT aortic valve calcium scoring (CT-AVC) quantify calcification activity and burden respectively. The overarching aim of this thesis was to evaluate the applications of these techniques to the study and management of aortic stenosis. METHODS AND RESULTS REPRODUCIBILITY The scan-rescan reproducibility of 18F-fluoride PET-CT and CT-AVC were investigated in 15 patients with mild, moderate and severe aortic stenosis who underwent repeated 18F-fluoride PET-CT scans 3.9±3.3 weeks apart. Modified techniques enhanced image quality and facilitated clear localization of calcification activity. Percentage error was reduced from ±63% to ±10% (tissue-to-background ratio most-diseased segment (MDS) mean of 1.55, bias -0.05, limits of agreement - 0·20 to +0·11). Excellent scan-rescan reproducibility was also observed for CT-AVC scoring (mean of differences 2% [limits of agreement, 16 to -12%]). AORTIC VALVE CALCIUM SCORE: SINGLE CENTRE STUDY Sex-specific CT-AVC thresholds (2065 in men and 1271 in women) have been proposed as a flow-independent technique for diagnosing severe aortic stenosis. In a prospective cohort study, the impact of CT-AVC scores upon echocardiographic measures of severity, disease progression and aortic valve replacement (AVR)/death were examined. Volunteers (20 controls, 20 with aortic sclerosis, 25 with mild, 33 with moderate and 23 with severe aortic stenosis) underwent CT-AVC and echocardiography at baseline and again at either 1 or 2-year time-points. Women required less calcification than men for the same degree of stenosis (p<0.001). Baseline CT-AVC measurements appeared to provide the best prediction of subsequent disease progression. After adjustment for age, sex, peak aortic jet velocity (Vmax) ≥ 4m/s and aortic valve area (AVA)<1 cm2, the published CT-AVC thresholds were the only independent predictor of AVR/death (hazard ratio = 6.39, 95% confidence intervals, 2.90-14.05, p<0.001). AORTIC VALVE CALCIUM SCORE: MULTICENTRE STUDY CT-AVC thresholds were next examined in an international multicenter registry incorporating a wide range of patient populations, scanner vendors and analysis platforms. Eight centres contributed data from 918 patients (age 77±10, 60% male, Vmax 3.88±0.90 m/s) who had undergone ECG-gated CT within 3 months of echocardiography. Of these 708 (77%) had concordant echocardiographic assessments, in whom our own optimum sex-specific CT-AVC thresholds (women 1377, men 2062 AU) were nearly identical to those previously published. These thresholds provided excellent discrimination for severe stenosis (c-statistic: women 0.92, men 0.88) and independently predicted AVR and death after adjustment for age, sex, Vmax ≥4 m/s and AVA <1 cm2 (hazards ratio, 3.02 [95% confidence intervals, 1.83-4.99], p<0.001). In patients with discordant echocardiographic assessments (n=210), CT-AVC thresholds predicted an adverse prognosis. BICUSPID AORTIC VALVES Within the multicentre study, higher continuity-derived estimates of aortic valve area were observed in patients with bicuspid valves (n=68, 1.07±0.35 cm) compared to those with tri-leaflet valves (0.89±0.36 cm p<0.001,). This was despite no differences in measurements of Vmax (p=0.152), or CT-AVC scores (p=0.313). The accuracy of AVA measurments in bicuspid valves was therefore tested against alternative markers of disease severity. AVA measurements in bicuspid valves demonstrated extremely weak associations with CT-AVC scores (r2=0.08, p=0.02) and failed to correlate with downstream markers of disease severity in the valve and myocardium and against clinical outcomes. AVA measurements in bicuspid patients also failed to independently predict AVR/death after adjustment for Vmax ≥4 m/s, age and gender. In this population CT-AVC thresholds (women 1377, men 2062 AU) again provided excellent discrimination for severe stenosis. CONCLUSIONS Optimised 18F-fluoride PET-CT scans quantify and localise calcification activity, consolidating its potential as a biomarker or end-point in clinical trials of novel therapies. CT calcium scoring of aortic valves is a reproducible technique, which provides diagnostic clarity in addition to powerful prediction of disease progression and adverse clinical events

Study of malondialdehyde as an oxidative stress marker in schizophrenia

Background: Schizophrenia is characterized by distortions in thinking, perception, emotions, language, sense of self and behaviour. It has been demonstrated that free radical-mediated damage has an important role in the pathophysiology of schizophrenia. The present study was undertaken to study malondialdehyde as an oxidative stress marker in first episode and chronic schizophrenic patients.Methods: 50 patients of first episode schizophrenia and 50 patients of chronic schizophrenia were included in the study. 50 numbers of age and sex matched healthy and apparently normal controls were also selected for study. Blood samples were drawn and analysed for malondialdehyde (MDA) from all participants.Results: The study shows significant increase in plasma malondialdehyde (MDA) levels in both first episode schizophrenics and chronic schizophrenic patients as compared to controls. When we compared levels of these parameters in first episode schizophrenics and chronic schizophrenics, we did not find significant difference.Conclusions: Findings in our study is suggesting that increase in the levels of plasma malondialdehyde (MDA) occurs due to increased lipid peroxidation in schizophrenics.