Development of Self-lubricating Nickel Based Composite Clad using Microwave Heating in Improving Resistance to Wear at Elevated Temperatures

G. Suresh,M. R. Ramesh,M. S. Srinath 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

This paper reports on a study of the high-temperature tribological performance of self-lubricating nickel-based compositeclad. A porous and crack free clad containing matrix, reinforcement, and lubricant phase is developed on titanium 31 alloyusing microwave irradiation. The microstructure of both NiCrSiB/WC and NiCrSiB/WC/Ag/BaF2 clad revealed very goodmetallurgical bonding with the substrate. The average microhardness of NiCrSiB/WC and NiCrSiB/WC/Ag/BaF2 clad is710.58 HV and 650.25 HV respectively, is comparatively higher than the titanium 31 substrate (320 HV). The addition of Agand BaF2solid lubricants in the clad endowing clad to operate at a broad temperature range. Compared with the NiCrSiB/WCclad, solid lubricant encapsulate clad has shown very low friction coefficient and wear rates. The sliding wear characteristicsof the clad were investigated by varying load and temperatures. The results revealed that oxide phases (NiO and Cr3O)andlubricant phases (Ag and BaWO4)formed at low and high temperatures are adequate to reduce delamination and material loss.

Medical student’s perception to different types of set induction in anatomy lectures

Suresh Narayanan,Suresh Narayanan,Nachiket Shankar,Vimala Ananthy 대한해부학회 2019 Anatomy & Cell Biology Vol.52 No.3

Set induction refers to the process of using a thought-provoking statement, interesting fact, or an audio-visual stimulus at the beginning of lecture to gain student’s attention and give an overview about the lecture topic. In the present study, students were introduced to three types of set induction namely narratives, food-based analogies and humor-based images or activities at the beginning of anatomy lecture and their response to it is collected and analyzed. The objective of the study is to estimate the difference in a questionnaire-based perception score between the three different types of set induction; estimate sex differences in the questionnaire-based perception score. Students rated the validated, 7-item perception questionnaire using a 5-point Likert scale. Students felt that food-based analogies and humor-based images were more interesting, motivated them to participate in lecture-discussion than the narrative set induction. The familiarity of set induction varied between all the three different types of set induction. There was no significant difference in the perception of different types of set induction between male and female undergraduate students. Based on the student’s feedback, it could also serve as a memory aid and ease the students learning experience. Majority of students responded positively to the use of set induction and recommended for its use in future classes.

K48- and K63-linked polyubiquitination of deubiquitinating enzyme USP44

Suresh, Bharathi,Ramakrishna, Suresh,Lee, Hey‑,Jin,Choi, Jong‑,Ho,Kim, Jin‑,Young,Ahn, Woong‑,Shick,Baek, Kwang‑,Hyun Wiley (John WileySons) 2010 Cell biology international Vol.34 No.8

The Importance of Ubiquitination and Deubiquitination in Cellular Reprogramming

Suresh, Bharathi,Lee, Junwon,Kim, Kye-Seong,Ramakrishna, Suresh Hindawi Publishing Corporation 2016 Stem cells international Vol.2016 No.-

<P>Ubiquitination of core stem cell transcription factors can directly affect stem cell maintenance and differentiation. Ubiquitination and deubiquitination must occur in a timely and well-coordinated manner to regulate the protein turnover of several stemness related proteins, resulting in optimal embryonic stem cell maintenance and differentiation. There are two switches: an E3 ubiquitin ligase enzyme that tags ubiquitin molecules to the target proteins for proteolysis and a second enzyme, the deubiquitinating enzyme (DUBs), that performs the opposite action, thereby preventing proteolysis. In order to maintain stemness and to allow for efficient differentiation, both ubiquitination and deubiquitination molecular switches must operate properly in a balanced manner. In this review, we have summarized the importance of the ubiquitination of core stem cell transcription factors, such as Oct3/4, c-Myc, Sox2, Klf4, Nanog, and LIN28, during cellular reprogramming. Furthermore, we emphasize the role of DUBs in regulating core stem cell transcriptional factors and their function in stem cell maintenance and differentiation. We also discuss the possibility of using DUBs, along with core transcription factors, to efficiently generate induced pluripotent stem cells. Our review provides a relatively new understanding regarding the importance of ubiquitination/deubiquitination of stem cell transcription factors for efficient cellular reprogramming.</P>

PEST Motif Sequence Regulating Human NANOG for Proteasomal Degradation

Ramakrishna, Suresh,Suresh, Bharathi,Lim, Key-Hwan,Cha, Byung-Hyun,Lee, Soo-Hong,Kim, Kwang-Soo,Baek, Kwang-Hyun Mary Ann Liebert 2011 STEM CELLS AND DEVELOPMENT Vol.20 No.9

The role of deubiquitinating enzymes in apoptosis

Ramakrishna, Suresh,Suresh, Bharathi,Baek, Kwang-Hyun Springer-Verlag 2011 Cellular and molecular life sciences Vol.68 No.1

Performance study of various discontinuous PWM strategies for multilevel inverters using generalized space vector algorithm

Suresh Kumar, A.,Sri Gowri, K.,Vijaya Kumar, M. The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1

The space vector (SV) pulse-width modulation (PWM) approach is extensively preferred in the control of multilevel inverters (MLI). In this paper, the implementation of various advanced discontinuous pulse-width modulation (ADPWM) strategies using a generalized space vector algorithm is presented. The ADPWM MIN, ADPWM MAX, and ADPWM 0~ADPWM 3, strategies are developed using a combination of advanced switching sequences 1012-2721 and 0121-7212. The output performance in terms of voltage THD, current THD, and reduction of common mode voltage (CMV) of a three-level inverter-fed induction motor for different ADPWM strategies is investigated initially through MATLAB simulation and comparison of the obtained results is presented. It can be observed that the ADPWM 1 strategy with the 0121-7212 switching sequence offered the best performance in terms of the voltage and current THD at the modulation range of 47.5 Hz to 50 Hz. In addition, it is validated experimentally. Experimental work is done on a V/f-controlled three-level inverter-fed induction motor with the help of dSPACE. To validate the study, experimental results of the line voltage, stator current, and CMV waveforms for the ADPWM 1 (optimal performance PWM strategy) are presented in comparison with the 0127 sequence at fundamental frequencies of 49 Hz and 30 Hz.

Reassessment of Relative Value in Shoulder and Elbow Surgery: Do Payment and Relative Value Units Reflect Reality?

Suresh K Nayar,Richard L. Skolasky,Dawn M LaPorte,Ryan M Zimmerman,Aviram M Giladi,Umasuthan Srikumaran 대한정형외과학회 2021 Clinics in Orthopedic Surgery Vol.13 No.1

Background: Many U.S. health care institutions have adopted compensation models based on work relative value units (wRVUs) to standardize payments and incentivize providers. A major determinant of payment and wRVU assignments is operative time. We sought to determine whether differences in estimated operative times between the Centers for Medicare & Medicaid Services (CMS) and the National Surgical Quality Improvement Program (NSQIP) contribute to payment and wRVU misvaluation for the most common shoulder/elbow procedures. Methods: We collected data on wRVUs, payments, and operative times from CMS for 29 types of isolated arthroscopic and open shoulder/elbow procedures. Using regression analysis, we compared relationships between these variables, in addition to median operative times reported by NSQIP (2013–2016). We then determined the relative valuation of each procedure based on operative time. Results: Seventy-nine percent of CMS operative time were longer than NSQIP time (R2 = 0.58), including, but not limited to, shoulder arthroplasty and arthroscopic shoulder surgery. The correlation between payments and operative times was stronger between CMS data (R2 = 0.61) than NSQIP data (R2 = 0.43). Similarly, the correlation between wRVUs and operative times was stronger when using CMS data (R2 = 0.87) than NSQIP data (R2 = 0.69). Nearly all arthroscopic shoulder procedures (aside from synovectomy, debridement, and decompression) were highly valued according to both datasets. Per NSQIP, compensation for revision total shoulder arthroplasty ($10.14/min; 0.26 wRVU/min) was higher than that for primary cases ($9.85, 0.23 wRVU/min) and nearly twice the CMS rate for revision cases ($5.84/min; 0.13 wRVU/min). Conclusions: CMS may overestimate operative times compared to actual operative times as recorded by NSQIP. Shorter operative times may render certain procedures more highly valued than others. Case examples show that this can potentially affect patient care and incentivize higher compensating procedures per operative time when less-involved, shorter operations have similar patient-reported outcomes.

Real-Time Implementation of Shunt Active Filter P-Q Control Strategy for Mitigation of Harmonics with Different Fuzzy M.F.s

Suresh Mikkili,Anup Kumar Panda 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.5

This research article presents a novel approach based on an instantaneous active and reactive power component (p-q) theory for generating reference currents for shunt active filter (SHAF). Three-phase reference current waveforms generated by proposed scheme are tracked by the three-phase voltage source converter in a hysteresis band control scheme. The performance of the SHAF using the p-q control strategy has been evaluated under various source conditions. The performance of the proposed control strategy has been evaluated in terms of harmonic mitigation and DC link voltage regulation. In order to maintain DC link voltage constant and to generate the compensating reference currents, we have developed Fuzzy logic controller with different(Trapezoidal, Triangular and Gaussian) fuzzy M.F.s. The proposed SHAF with different fuzzy M.F.s is able to eliminate the uncertainty in the system and SHAF gains outstanding compensation abilities. The detailed simulation results using MATLAB/SIMULINK software are presented to support the feasibility of proposed control strategy. To validate the proposed approach, the system is also implemented on a real time digital simulator and adequate results are reported for its verifications.

Racial Disparity in Time to Surgery and Complications for Hip Fracture Patients

Suresh K. Nayar,Majd Marrache,Iman Ali,Jarred Bressner,Micheal Raad,Babar Shafiq,Uma Srikumaran 대한정형외과학회 2020 Clinics in Orthopedic Surgery Vol.12 No.4

Background: Racial and ethnic disparities in orthopedic surgery may be associated with worse perioperative complications. For patients with hip fractures, studies have shown that early surgery, typically within 24 to 48 hours of admission, may decrease postoperative morbidity and mortality. Our objective was to determine whether race is associated with longer time to surgery from hospital presentation and increased postoperative complications. Methods: We queried the National Surgical Quality Improvement Program database from 2011 to 2017 for patients (> 65 years) with hip fractures who underwent surgical fixation. Patients were identified using Current Procedural Terminology codes (27235, 27236, 27244, and 27245). Delayed surgery was defined as time to surgery from hospital admission that was greater than 48 hours. Time to surgery was compared between races using analysis of variance. A multivariate logistic regression analysis adjusting for comorbidities, age, sex, and surgery was performed to determine the likelihood of delayed surgery and rate of postoperative complications. Results: A total of 58,456 patients who underwent surgery for a hip fracture were included in this study. Seventy-two percent were female patients and the median age was 87 years. The median time to surgery across all patients was 24 hours. African Americans had the longest time to surgery (30.4 ± 27.6 hours) compared to Asians (26.5 ± 24.6 hours), whites (25.8 ± 23.4 hours), and other races (22.7 ± 22.0 hours) (p < 0.001). After adjusting for comorbidities, age, sex, and surgery, there was a 43% increase in the odds of delayed surgery among American Africans compared to whites (odds ratio, 1.43; 95% confidence interval, 1.29–1.58; p < 0.001). Despite higher odds of reintubation, pulmonary embolism, renal insufficiency or failure, and cardiac arrest in African Americans, mortality was significantly lower compared to white patients (4.41% vs. 6.02%, p < 0.001). Asian Americans had the lowest mortality rate (3.84%). Conclusions: A significant disparity in time to surgery and perioperative complications was seen amongst different races with only African Americans having a longer time to surgery than whites. Further study is needed to determine the etiology of this disparity and highlights the need for targeted strategies to help at-risk patient populations.