Mechanistic insights into the interaction between energetic oxygen ions and nanosized ZnFe₂O₄: XAS-XMCD investigations

Singh, Jitendra Pal,Kaur, Baljeet,Sharma, Aditya,Kim, So Hee,Gautam, Sanjeev,Srivastava, Ramesh Chandra,Goyal, Navdeep,Lim, Weol Cheol,Lin, H.-J.,Chen, J. M.,Asokan, K.,Kanjilal, D.,Won, Sung Ok,Lee, The Royal Society of Chemistry 2018 Physical Chemistry Chemical Physics Vol.20 No.17

<P>The interactions of energetic ions with multi-cation compounds and their consequences in terms of changes in the local electronic structure, which may facilitate intriguing hybridization between O 2p and metal d orbitals and magnetic ordering, are the subject of debate and require a deep understanding of energy transfer processes and magnetic exchange mechanisms. In this study, nanocrystals of ZnFe2O4 were exposed to O<SUP>7+</SUP> ions with an energy of 100 MeV to understand, qualitatively and quantitatively, the metal-ligand field interactions, cation migration and magnetic exchange interactions by employing X-ray absorption fine structure measurements and X-ray magnetic circular dichroism to get deeper mechanistic insights. Nanosized zinc ferrite nanoparticles (NPs) with a size of ∼16 nm synthesized in the cubic spinel phase exhibited deterioration of the crystalline phase when 100 MeV O<SUP>7+</SUP> ions passed through them. However, the size of these NPs remained almost the same. The behaviour of crystal deterioration is associated with the confinement of heat in this interaction. The energy confined inside the nanoparticles promotes cation redistribution as well as the modification of the local electronic structure. Prior to this interaction, almost 42% of Zn<SUP>2+</SUP> ions occupied AO4 tetrahedra; however, this value increased to 63% after the interaction. An inverse effect was observed for metal ion occupancies in BO6 octahedra. The L-edge spectra of Fe and Zn reveal that the spin and valence states of the metal ions were not affected by this interaction. This effect is also supported by K-edge measurements for Fe and Zn. The t2g/eg intensity ratio in the O K-edge spectra decreased after this interaction, which is associated with detachment of Zn<SUP>2+</SUP> ions from the lattice. The extent of hybridization, as estimated from the ratio of the post-edge to the pre-edge region of the O K-edge spectra, decreased after this interaction. The metal-oxygen and metal-metal bond lengths were modified as a result of this interaction, as determined from extended X-ray absorption fine structure measurements. These measurements further support the observation of cation migration from AO4 tetrahedra to AO6 octahedra and <I>vice versa</I>. The Fe L-edge magnetic circular dichroism spectra indicate that Fe<SUP>3+</SUP> ions occupying sites in AO4 tetrahedra and BO6 octahedra exhibited antiferromagnetic-like ordering prior to this interaction. The NPs that interacted with energetic O ions displayed a different kind of magnetic ordering.</P>

Comparative antidiabetic activity of different fractions of Enicostemma littorale Blume in streptozotocin induced NIDDM rats

Vishwakarma, Santosh L.,Rajani, M.,Goyal, Ramesh K. Kyung Hee Oriental Medicine Research Center 2003 Oriental pharmacy and experimental medicine Vol.3 No.4

Aqueous extract of Enicostemma littorale is reported to have antidiabetic activity. In the present investigation, we studied the effect of aqueous extract of E. littorale and its different fractions i.e., toluene, chloroform, ethyl acetate, n-butanol fractions and remaining residual fraction in streptozotocin (STZ)-induced neonatal type 2 diabetic rats. Fasting glucose and insulin levels in NIDDM were significantly (P<0.05) higher than control rats and they were significantly decreased by treatment with aqueous extract of E. littorale and its n-butanol and ethyl acetate fractions. Results of oral glucose tolerance test (OGTT) showed that aqueous extract and its n-butanol and ethyl acetate fractions significantly (P<0.05) decrease both $AUC_{glucose}$ and $AUC_{insulin}$ values in NIDDM treated groups. Insulin sensitivity $(K_{ITT})$ index of NIDDM control was significantly lower as compared to normal control and this was significantly (P<0.05) increased after treatment with aqueous extract, its n-butanol and ethyl acetate fractions. Treatment with aqueous extract of E. littorale and its n-butanol and ethyl acetate fractions lowered the elevated cholesterol and triglyceride levels observed in NIDDM rats. Treatment with aqueous extract of E. littorale and its n-butanol fraction showed significant decrease in creatinine, urea, SGPT and SGOT levels as compared to NIDDM control rats. However ethyl acetate fraction showed significant changes only in creatinine and SGOT levels, and not in the levels of urea, and SGPT as compared to NIDDM control rats. Treatment with toluene, chloroform and residual fractions of E. littorale did not produce any effect on glucose, insulin, triglyceride, cholesterol, creatinine, urea, SGPT or SGOT levels as compared to NIDDM control rats. Our data suggest that n-butanol and ethyl acetate fractions contain the active compounds which may be responsible for the above activity and associated complications in NIDDM diabetes mellitus.

Effect of fermented Panax ginseng extract (GINST) on oxidative stress and antioxidant activities in major organs of aged rats

Ramesh, T.,Kim, S.W.,Sung, J.H.,Hwang, S.Y.,Sohn, S.H.,Yoo, S.K.,Kim, S.K. Pergamon Press ; Elsevier Science Ltd 2012 Experimental Gerontology Vol.47 No.1

The intracellular levels of oxidant and antioxidant balances are gradually distorted during the aging process. An age associated elevation of oxidative stress occurring throughout the lifetime is hypothesized to be the major cause of aging. The present study was undertaken to evaluate the putative antioxidant activity of the fermented Panax ginseng extract (GINST) on lipid peroxidation and antioxidant status of major organs of aged rats compared to young rats. Increased levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea and creatinine were observed in the serum of aged rats. Increased levels of malondialdehyde (MDA) and significantly lowered activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione-S-transferase (GST) were observed in the liver, kidneys, heart and lungs of aged rats, when compared with those in young rats. Quantitative analysis of the non-enzymatic antioxidants such as reduced glutathione (GSH), ascorbic acid and α-tocopherol levels showed significantly lower values in the liver, kidneys, heart and lungs of aged rats. On the other hand, administration of the fermented Panax ginseng extract (GINST) to aged rats resulted in increased activities of SOD, CAT, GPx, GR and GST as well as elevation in GSH, ascorbic acid and α-tocopherol levels. Besides, the level of MDA, AST, ALT, urea and creatinine were reduced on administration of GINST to aged rats. These results suggested that treatment of GINST can improve the antioxidant status during aging, thereby minimizing the oxidative stress and occurrence of age-related disorders associated with free radicals.

Cordycepin (3'-deoxyadenosine) attenuates age-related oxidative stress and ameliorates antioxidant capacity in rats

Ramesh, T.,Yoo, S.K.,Kim, S.W.,Hwang, S.Y.,Sohn, S.H.,Kim, I.W.,Kim, S.K. Pergamon Press ; Elsevier Science Ltd 2012 Experimental Gerontology Vol.47 No.12

Free radical-induced oxidative damage is considered to be the most important consequence of the aging process. The activities and capacities of antioxidant systems of cells decline with increased age, leading to the gradual loss of pro-oxidant/antioxidant balance and resulting in increased oxidative stress. Our investigation was focused on the effects of cordycepin (3'-deoxyadenosine) on lipid peroxidation and antioxidation in aged rats. Age-associated decline in the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST), reduced glutathione (GSH), vitamin C and vitamin E, and elevated levels of malondialdehyde (MDA) were observed in the liver, kidneys, heart and lungs of aged rats, when compared to young rats. Furthermore, serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine were found to be significantly elevated in aged rats compared to young rats. Aged rats receiving cordycepin treatment show increased activity of SOD, CAT, GPx, GR and GST, and elevated levels of GSH, and vitamins C and E such that the values of most of these parameters did not differ significantly from those found in young rats. In addition, the levels of MDA, AST, ALT, urea and creatinine became reduced upon administration of cordycepin to aged rats. These results suggest that cordycepin is effective for restoring antioxidant status and decreasing lipid peroxidation in aged rats.

Modeling of Leakages in Fixed-Matrix Regenerators

Ramesh K. Shah,Teodor Skiepko 대한기계학회 1998 Heat transter conference Vol.6 No.1

A First and Second Law Analysis of Phase Change Heat Exchangers for Energy Storage

K. Poornathresan,K. N. Ramesh,A. Venkata Ramayya 대한기계학회 1998 Heat transter conference Vol.5 No.1

PARALLEL URANS SIMULATIONS OF SYNTHETIC JET FLOW FIELDS AND COMPARISONS WITH EXPERIMENTS

Ramesh K. Agarwal,Jing Cui 한국전산유체공학회 2006 한국전산유체공학회 학술대회논문집 Vol.2006 No.5

IMPLICIT KINETIC SCHEMES FOR THE EULER AND IDEALMHD EQUATIONS

Ramesh K. Agarwal,H.S. R. Reksoprodjo 한국전산유체공학회 2006 한국전산유체공학회 학술대회논문집 Vol.2006 No.5

On decompositions of a weaker form of intuitionistic fuzzy continuity

K. Ramesh,M. Thirumalaiswamy 장전수학회 2014 Proceedings of the Jangjeon mathematical society Vol.17 No.1

On decompositions of a weaker form of intuitionistic fuzzy continuity

Effects of Enzyme Addition to Broiler Diets Containing Varying Levels of Double Zero Rapeseed Meal

Ramesh, K.R.,Devegowda, G.,Khosravinia, H. Asian Australasian Association of Animal Productio 2006 Animal Bioscience Vol.19 No.9

Maize-soybean meal diets with 0, 100, 200 and 300 g/kg double zero rapeseed meal ('00' RSM) with and without an enzyme mixture (xylanase, pectinase, cellulase) at a level of 1.6 g/kg were evaluated with 624 day-old broiler chicks for 5 weeks. The birds were randomly allocated to eight dietary treatments with three replicates of 26 birds each. Average daily gain (ADG) and feed intake (FI) were recorded weekly and ileal viscosity, organ weights, serum enzyme activity, hormonal profile and hematological parameters were measured at the end of week 5. Average daily gain during the weekly periods was significantly influenced by the dietary level of '00'RSM (p<0.01). Inclusion of '00' RSM improved the ADG up to day 28 with the increased level; beyond that time no improvement was recorded when compared to control groups. However, ADG from 1-35 days was significantly different between 300 g/kg inclusion level of '00' RSM and the control diet. Inconsistent decline in feed intake and feed conversion ratio was observed up to day 21 and the trend was reversed thereafter. The proportion of '00' RSM in the diet had a significant ($p{\leq}0.05$) influence on thyroid weight but had no effect on the relative weights of liver and heart, serum enzyme activities (${\gamma}$-glutamyl transferase, alanine amino transferase and aspartate amino transferase), thyroid hormones ($T_3$ and $T_4$), hemoglobin level and hematocrit. Significant improvement in ADG was recorded during the 2nd week of age with the addition of enzyme, whereas for all other periods, including the whole period of the trial, higher but non-significant ADG was observed. FI and FCR were not affected by the addition of enzyme but there was a numerical reduction in FCR during the whole period. The addition of enzyme reduced the ileal viscosity at all levels of '00' RSM inclusion. The results suggest that '00' RSM can be included up to 300 g/kg in broiler diets without any adverse effects on health and performance. The addition of commercial enzyme mixture containing xylanase, pectinase, cellulase to broiler diets containing '00'RSM has some effect on growth rate and feed conversion efficiency.