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C. H. Suresh Vidyasagar,D. Benny Karunakar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.11
The present research work investigates the effects of nano yttrium (Y) and SPS mechanism on various properties of AA2024-Y nanocomposites. Five nanocomposites are developed through SPS by reinforcing varying amounts of nano yttrium in therange of 0.1–0.5 wt% to the AA2024 powder matrix. An unreinforced AA2024 is also sintered by SPS as a benchmark tocompare the mechanical properties. The microstructure characterization of the developed nanocomposites is carried out byoptical microscope and field emission scanning electron microscope and the mechanical properties like microhardness andtensile strength is evaluated by computerized Vickers hardness testing machine and universal testing machine (UTM) respectively. The mechanical properties and the corresponding microstructures of composites are correlated. The experimentalresults showed that the mechanical properties gradually increased to a certain level and then decrease. There is a clear trendof initial increase and late decrease in the mechanical properties. An optimum amount of nano yttrium (0.3 wt%) additionis observed to be the maximum limit of reinforcement content to create favorable conditions during spark plasma sinteringfor the promotion of densification and Al2Cuprecipitation in the α-Al matrix leading to an improvement in the mechanicalproperties of the nanocomposites. Among the developed composites, the highest hardness (130 HV), yield strength (YS)(386 MPa) and UTS (462 MPa) are obtained in the AA2024 composite sample reinforced with 0.3 wt% addition of nanoyttrium. Densities close to theoretical density are achieved in all the composite samples.
( Laxmaiah Manchikanti ),( Vidyasagar Pampati ),( Alan D. Kaye ),( Joshua A. Hirsch ) 대한통증학회 2018 The Korean Journal of Pain Vol.31 No.1
Background: Related to escalating health care costs and the questionable effectiveness of multiple interventions including lumbar facet joint interventions, cost effectiveness or cost utility analysis has become the cornerstone of evidence-based medicine influencing coverage decisions. Methods: Cost utility of therapeutic lumbar facet joint nerve blocks in managing chronic low back pain was performed utilizing data from a randomized, double-blind, controlled trial with a 2-year follow-up, with direct payment data from 2016. Based on the data from surgical interventions, utilizing the lowest proportion of direct procedural costs of 60%, total cost utility per quality adjusted life year (QALY) was determined by multiplying the derived direct cost at 1.67. Results: Patients in this trial on average received 5.6 ± 2.6 procedures over a period of 2 years, with average relief over a period of 2 years of 82.8 ± 29.6 weeks with 19 ± 18.77 weeks of improvement per procedure. Procedural cost for one-year improvement in quality of life showed USD $2,654.08. Estimated total costs, including indirect costs and drugs with multiplication of direct costs at 1.67, showed a cost of USD $4,432 per QALY. Conclusions: The analysis of therapeutic lumbar facet joint nerve blocks in the treatment of chronic low back pain shows clinical effectiveness and cost utility at USD $2,654.08 for the direct costs of the procedures, and USD $4,432 for the estimated overall cost per one year of QALY, in chronic persistent low back pain non-responsive to conservative management. (Korean J Pain 2018; 31: 27-38)
( Divyanshu Goyal ),( Sandeep Yadav ),( Vidyasagar Jvs ) 대한슬관절학회 2019 대한슬관절학회지 Vol.31 No.1
Purpose: The purpose of this study was to determine the effect of the weave technique for hamstring graft preparation on the diameter of the prepared graft, functional outcome, and need for harvesting of semitendinosus and gracilis (ST + G) or semitendinosus alone (ST). Materials and Methods: This retrospective study evaluated 340 patients who underwent arthroscopic anterior cruciate ligament (ACL) reconstruction from January 2013 to December 2015. Our protocol for graft preparation is that the graft length must be a minimum of 8 cm and the diameter must be between 7 and 10 mm. The parallelgraft preparation technique was used in 189 patient and the weave technique was used in 151 patients. Outcome was measured by using stress radiographs and International Knee Documentation Committee (IKDC) 2000 score. Results: In the parallel-graft preparation group, ST + G was used in 99 patients and ST was used in 90 patients. In the weave-graft preparation group, ST + G was used in 38 patients and ST alone was sufficient in 113 patients. The need for G harvest was less in the weave-technique group (p < 0.0001). There was no statistically significant difference at 2 years of follow-up in stress laxiometry, IKDC 2000 scores and rerupture rates between the two groups. Conclusion: The weave technique helps to reduce the need for G harvest without compromising functional outcome. Level of evidence IV.
Palanisamy R.,Karthikeyan D.,Vidyasagar S.,Kalyanasundaram V.,Selvakumar K.,Vijayakumar K.,Selvabharathi D. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4
In this paper, three phase four wire fi ve level Neutral Point Clamped Inverter (NPCI) based Static synchronous Compensator (STATCOM) is implemented for reactive power control and neutral current elimination. Three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) control strategy is developed to control this 5-level NPC inverter. The behaviour of static synchronous compensator is analyzed and reactive power control is done using constant DC voltage. The objective of this compensating method is to provide balanced and sinusoidal source currents under unbalanced and nonlinear load conditions and reactive power control. The 3D-SVPWM technique provides reduced harmonic content in output voltage and current, controlled source current, minimized common mode voltage and improved output voltage. In 3D-SVPWM, switching pulses are generated with non-redundant switching states, which lead to reduce the complexity in switching time calculation and computational time is less. The highlights of the paper includes the neutral current is reduced to 0.25A, source current harmonics is minimized and it provides balanced and sinusoidal source currents with help of STATCOM compensation. The simulation and experimental results demonstrates the sinusoidal and harmonics free source current and minimized neutral current for four wire fi ve level NPCI based STATCOM.
( Laxmaiah Manchikanti ),( Vijay Singh ),( Vidyasagar Pampati ),( Frank Je Falco ),( Joshua A Hirsch ) 대한통증학회 2015 The Korean Journal of Pain Vol.28 No.1
Background: Epidural injections are performed utilizing 3 approaches in the lumbar spine: caudal, interlaminar, and transforaminal. The literature on the efficacy of epidural injections has been sporadic. There are few high-quality randomized trials performed under fluoroscopy in managing disc herniation that have a long-term follow-up and appropriate outcome parameters. There is also a lack of literature comparing the efficacy of these 3 approaches. Methods: This manuscript analyzes data from 3 randomized controlled trials that assessed a total of 360 patients with lumbar disc herniation. There were 120 patients per trial either receiving local anesthetic alone (60 patients) or local anesthetic with steroids (60 patients). Results: Analysis showed similar efficacy for caudal, interlaminar, and transforaminal approaches in managing chronic pain and disability from disc herniation. The analysis of caudal epidural injections showed the potential superiority of steroids compared with local anesthetic alone a 2-year follow-up, based on the average relief per procedure. In the interlaminar group, results were somewhat superior for pain relief in the steroid group at 6 months and functional status at 12 months. Interlaminar epidurals provided improvement in a significantly higher proportion of patients. The proportion of patients nonresponsive to initial injections was also lower in the group for local anesthetic with steroid in the interlaminar trial. Conclusions: The results of this assessment show significant improvement in patients suffering from chronic lumbar disc herniation with 3 lumbar epidural approaches with local anesthetic alone, or using steroids with long-term follow-up of up to 2 years, in a contemporary interventional pain management setting. (Korean J Pain 2015; 28: 11-21)
siMacro: A Fast and Easy Data Processing Tool for Cell-Based Genomewide siRNA Screens
Nitin Kumar Singh,Bo Yeun Seo,Mathukumalli Vidyasagar,Michael A. White,김현석 한국유전체학회 2013 Genomics & informatics Vol.11 No.1
Growing numbers of studies employ cell line-based systematic short interfering RNA (siRNA) screens to study gene functions and to identify drug targets. As multiple sources of variations that are unique to siRNA screens exist, there is a growing demand for a computational tool that generates normalized values and standardized scores. However, only a few tools have been available so far with limited usability. Here, we present siMacro, a fast and easy-to-use Microsoft Office Excel-based tool with a graphic user interface, designed to process single-condition or two-condition synthetic screen datasets. siMacro normalizes position and batch effects, censors outlier samples, and calculates Z-scores and robust Z-scores, with a spreadsheet output of >120,000 samples in under 1 minute.