Magnetic ground state of the multiferroic hexagonal LuFeO3

Suresh, Pittala,Vijaya Laxmi, K.,Bera, A. K.,Yusuf, S. M.,Chittari, Bheema Lingam,Jung, Jeil,Anil Kumar, P. S. American Physical Society 2018 Physical Review B Vol.97 No.18

<P>The structural, electric, and magnetic properties of bulk hexagonal LuFeO3 are investigated. Single phase hexagonal LuFeO3 has been successfully stabilized in the bulk form without any doping by sol-gel method. The hexagonal crystal structure with P6(3)cm space group has been confirmed by x-ray-diffraction, neutron-diffraction, and Raman spectroscopy study at room temperature. Neutron diffraction confirms the hexagonal phase of LuFeO3 persists down to 6 K. Further, the x-ray photoelectron spectroscopy established the 3+ oxidation state of Fe ions. The temperature-dependent magnetic dc susceptibility, specific heat, and neutron-diffraction studies confirm an antiferromagnetic ordering below the Neel temperature (T-N) similar to 130 K. Analysis of magnetic neutron-diffraction patterns reveals an in-plane (ab-plane) 120 degrees antiferromagnetic structure, characterized by a propagation vector k = (0 0 0) with an ordered moment of 2.84 mu(B)/Fe3+ at 6 K. The 120 degrees antifferomagnetic ordering is further confirmed by spin-orbit coupling density functional theory calculations. The on-site coulomb interaction (U) and Hund's parameter (J(H)) on Fe atoms reproduced the neutron-diffraction Gamma(1) spin pattern among the Fe atoms. P-E loop measurements at room temperature confirm an intrinsic ferroelectricity of the sample with remnant polarization P-r similar to 0.18 mu(C) cm(2). A clear anomaly in the dielectric data is observed at similar to T-N revealing the presence of magnetoelectric coupling. A change in the lattice constants at T-N has also been found, indicating the presence of a strong magnetoelastic coupling. Thus a coupling between lattice, electric, and magnetic degrees of freedom is established in bulk hexagonal LuFeO3.</P>

Spin polarization studies in half-metallic Co2TiX (X ¼ Ge and Sn) Heusler alloys

Lakhan Bainsla,K.G. Suresh 한국물리학회 2016 Current Applied Physics Vol.16 No.1

In this paper, we investigated the Co2TiX (X ¼ Ge, Sn) Heusler alloys by structural, magnetic and spin polarization measurements to probe the half-metallic nature. Alloys were synthesized using the arc melting technique, and found to exist in L21 crystal structure with Fm-3m space group. Curie temperature (TC) is found to be 384 and 371 K for Co2TiGe and Co2TiSn respectively. The saturation magnetization (MS) value of 1.8 and 2.0 mB/f.u. are obtained at 5 K for Co2TiGe and Co2TiSn respectively, compared to 2.0 mB/f.u. calculated by Slater-Pauling rule. To obtain the spin polarization value, differential conductance curves were recorded at the ferromagnetic/superconducting point contact at 4.2 K. The current spin polarization (P) value of 0.63 ± 0.03 and 0.64 ± 0.02 were deduced for Co2TiGe and Co2TiSn respectively. Considering the high current spin polarization and TC, these materials appear to be promising for spintronic devices.

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.

Experimental study of wind-induced pressures on tall buildings of different shapes

Suresh K Nagar,Ritu Raj,Nirendra Dev 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.31 No.5

The modern tall buildings are often constructed as an unconventional plan and as twin buildings. Wind load on the tall building is significantly influenced by the presence of another building in the near vicinity. So, it is imperative to study wind forces on an unconventional plan shaped tall building. Mean wind pressure coefficients of a square and ‘H’ plan shape tall buildings are investigated using wind tunnel experiments. The experiments were carried out for various wind directions from 00 to 900 at an interval of 300 and various locations of the identical interfering building. The experimental results are presented at the windward face from the viewpoint of effects on cladding design. To quantify the interference effects, interference factors (I.F) are calculated. Mean pressure coefficients of both models are compared for isolated and interference conditions. The results show that pressure reduces with an increase in wind angle till 600 wind direction. The interfering building at full blockage interference condition generates more suction than the other two conditions. The interference factor for both models is less than unity. H-plan building model is subjected to a higher pressure than the square model.

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.

Algal photosynthetic responses to toxic metals and herbicides assessed by chlorophyll a fluorescence

Suresh Kumar, K.,Dahms, H.U.,Lee, J.S.,Kim, H.C.,Lee, W.C.,Shin, K.H. Academic Press 2014 Ecotoxicology and environmental safety Vol.104 No.-

Chlorophyll a fluorescence is established as a rapid, non-intrusive technique to monitor photosynthetic performance of plants and algae, as well as to analyze their protective responses. Apart from its utility in determining the physiological status of photosynthesizers in the natural environment, chlorophyll a fluorescence-based methods are applied in ecophysiological and toxicological studies to examine the effect of environmental changes and pollutants on plants and algae (microalgae and seaweeds). Pollutants or environmental changes cause alteration of the photosynthetic capacity which could be evaluated by fluorescence kinetics. Hence, evaluating key fluorescence parameters and assessing photosynthetic performances would provide an insight regarding the probable causes of changes in photosynthetic performances. This technique quintessentially provides non-invasive determination of changes in the photosynthetic apparatus prior to the appearance of visible damage. It is reliable, economically feasible, time-saving, highly sensitive, versatile, accurate, non-invasive and portable; thereby comprising an excellent alternative for detecting pollution. The present review demonstrates the applicability of chlorophyll a fluorescence in determining photochemical responses of algae exposed to environmental toxicants (such as toxic metals and herbicides).

Optimal designing of skip lot sampling plan of type SkSP-2 with double sampling plan as the reference plan under generalized exponential distribution

Suresh, K.K.,Kavithamani, M. The Korean Reliability Society 2014 International Journal of Reliability and Applicati Vol.15 No.2

In this paper, a optimal designing methodology is proposed to determine the parameters for skip-lot sampling plan of type SkSP-2 plan with double sampling plan as reference plan, when the lifetime of the product follows generalized exponential distribution. The two points on the operating characteristic curve approach are used to find the optimal parameters for the proposed plan. The plan parameters are determined so as to minimize the average sample number subject to satisfying simultaneously both producer and consumer risks at the acceptable and limiting quality levels respectively.

Image Based Mutual Authentication to Enhance the Web Security

K. Suresh Kumar,T. Sasikala 보안공학연구지원센터 2016 International Journal of u- and e- Service, Scienc Vol.9 No.11

CAPTCHAs are an imperative and broadly used modern Internet technology to reduce the risk of reducing the computerized agents to programmatically use web connected resources such as online e-mail accounts, online polls, Web-based comment systems, Web-based SMS portals and so on. The designing of security algorithms utilizing captcha can be a useful security mechanism. There are several security attacks and survival of many phishing websites. In current systems, two factor authentications, One Time Password (OTP) are used to overcome these issues. In case of OTP, mobile technology is used to send the password to the client for confirmation, in some cases, mostly handheld mobiles may not be within the reach or there may be several other issues like network traffic and delay in receiving passwords. These problems decrease the capability of authentication. Here the proposed system is technology independent and behavior based authentication system, where system performs complete authentication through website using Image CAPTCHA. Behavior based authentication is done through appropriate selection and cropping of image at the accurate location. This proposed system ultimately enables us to substantiate whether the user is an authenticated user and website is an authenticated website The performance of the system has been analyzed using shoulder surfing, brute force, dictionary, random and reply attack to prove the web security.

Introduction of the Indian Society for Mass Spectrometry (ISMAS) (http:// www.ismas.org)

( Suresh K. Aggarwal ) 한국질량분석학회 2012 Mass spectrometry letters Vol.3 No.1

Optimal designing of skip lot sampling plan of type SkSP-2 with double sampling plan as the reference plan under generalized exponential distribution

K. K. Suresh,M. Kavithamani 한국신뢰성학회 2014 International Journal of Reliability and Applicati Vol.15 No.2

In this paper, a optimal designing methodology is proposed to determine the parameters for skip-lot sampling plan of type SkSP-2 plan with double sampling plan as reference plan, when the lifetime of the product follows generalized exponential distribution. The two points on the operating characteristic curve approach are used to find the optimal parameters for the proposed plan. The plan parameters are determined so as to minimize the average sample number subject to satisfying simultaneously both producer and consumer risks at the acceptable and limiting quality levels respectively.