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.

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

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).

Gas-phase mercury removal through sulfur impregnated porous carbon

K. Suresh Kumar Reddy,Ahmed Al Shoaibi,C. Srinivasakannan 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Gas phase mercury removal is a vital unit operation in gas processing industries. The present work attempts to prepare a sulfur impregnated carbon at optimized experimental conditions and compares its elemental adsorption capacity with the number of commercially available carbon based adsorbents. The effect of adsorption temperature on mercury adsorption capacity has been estimated for the prepared sulfur impregnated carbon. The adsorption capacity was found to increase with increase in adsorption temperature owing to the chemisorption nature of the adsorption. The adsorption isotherms were generated at three different temperatures and were found to close adhere to the Langmuir Isotherm model. The adsorption capacity was found to increase until 140℃, while decrease beyond, which was attributed to the softening and agglomeration of sulfur. The maximum adsorption capacity of 4325 mg/g was observed at a temperature of 140℃. A comparison of the relative adsorption capacity of various adsorbent at 30℃, revealed the adsorption capacity of the sulfur impregnated carbon prepared in the present work much higher than the commercially available carbons. The high adsorption capacities with simple preparation techniques favor the commercial mercury adoption process.

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.

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.

Information and Communication Management Systems (ICMS) in India –Connecting the Resource Poor Farmers to Knowledge and Institutions

Suresh K Mudda,Ravikumar N K,Chitti B Giddi 한국농식품정보과학회 2016 Agribusiness and Information Management Vol.8 No.1

Information and communication technologies (ICTs) have always mattered in agriculture too. In day-to-day practices of agriculture and allied sectors, the farmers often share their information. Changing weather patterns, soil conditions, pests and diseases always throw challenges to small and marginal farmers. So, the farmer needs up-dated information to cope with and even benefit from these changes. In the developing countries like India, where agriculture still plays a crucial role (over 58% of the rural households depend on agriculture as their livelihood) and the rising population from 1027 million to 1419 million during 2001-16 (a total rise of 38 percent or 1.3 percent per year) pose a lot of pressure on land and other resources to meet the food security needs on one hand and to meet the challenges of globalization on the other. Understanding and addressing these challenges are very crucial, in which ICT can play a major role. With the booming mobile, wireless, and Internet industries, ICT has found a foothold even in poor marginal and smallholder farms and in their activities. The survey conducted among the 120 farmers in Srikakulam district in India revealed that, ICT has revolutionized the agriculture in the modern days. Production and marketing information is accessed by 91% of the sample farmers through mobile in 2015, where it was only 5% in 2005. The extent of use of mobile phones by the farmers varied with the decision to be taken by them like Harvesting, packing, and storing (94%), Selling Decision (91%), Seed purchase (89%), Application of fertilizers and pesticides (88%) and Land preparation and planting (84%), other package of practices (77%). The farmers further opined that, ‘Voice’ was the dominating source of communication (96%) compared to Short Message Service (SMS) (only 27%) and Internet access (10%), as majority are illiterate. The use of camera (71%), Bluetooth (33%), Radio (61%) TV (41%) are the other means of sharing the information. In this context of importance of ICTs in Indian agriculture, greater attention justifies about the applications of ICT’s to alleviate poverty and promote economic growth of the farming population.

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.

Forging of cast Mg-3Sn-2Ca-0.4Al-0.4Si magnesium alloy using processing map

K. P. Rao,K. Suresh,Y. V. R. K. Prasad,N. Hort,K. U. Kainer 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.6

Mg-3Sn-2Ca (TX32) alloy has good creep resistance but limited workability. Minor amounts of Al and Si have been added to TX32 for improving its hot workability. The processing map for the TX32-0.4Al-0.4Si alloy exhibited two workability domains in the temperature and strain rate ranges: (1) 310-415°C/0.0003-0.003 s -1 and (2) 430-500°C/0.003-3 s -1 . The alloy exhibited flow instability at temperatures < 350°C at strain rates > 0.01 s -1 . The alloy has been forged to produce a cup shape component to validate these findings of processing map. Finite-element (FE) simulation has been performed for obtaining the local variations of strain and strain rate within the forging. The microstructures of the forged components under the optimal domain conditions revealed dynamically recrystallized grains, and those forged in the flow instability regime have fractured and exhibited flow localization bands and cracks. The experimental loadstroke curves correlated well with those obtained by FE simulation.