Physio-Morphological Changes in a Riboflavin Producer Eremothecium ashbyii DT1 and UV Mutants in Submerged Fermentation

Venugopal, Pujari,Chandra, T. S. 한국미생물 · 생명공학회 2001 Journal of microbiology and biotechnology Vol.11 No.4

By UV-irradiation of Eremothecium ashbyii DTl, a highly flavinogenic mutant (UV-18-57) and a nonflavinogenic mutant (UV-85) were obtained. The physio-morphological characteristics of these three strains were studied on glucose medium in submerged fermentation. Glucose utilization and mycelial growth occurred in 0-2 days of fermentation. By the third day, the biomass had declined. Extracellular riboflavin excretion was distinct from the second day, reaching a maximum rate by the fourth day. The hyphae of the highly flavinogenic mutant UV-18-57 were broader than DTI, while the nonflavinogenic UV-85 hyphae were very thin. Riboflavin accumulation was high in UV-18-57 (extracellular riboflavin, 825㎍/ml, and intracellular, 490㎍/ml) and caused the mycelia to swell into bulbous forms. Riboflavin accumulation was less in DTI (108㎍/ml extracellular and 24㎍/ml intracellular) and correspondingly its hyphae were thinner than those of UV-18-57 and swollen bulbous mycelia were not prominent. UV-85 was nonflavinogenic and, accordingly, its morphological characteristics included long thin filaments with no intracellular riboflavin accumulation. A large number of greenish fluorescence spores were seen in UV-18-57, whereas DTI had less spores and UV-85 was nonsporulating. Sporulation is correlated with riboflavin production. UV- 18-57 had better mycelial integrity and lysis started only by the seventh day, whereas DTI and UV-85 started to lyze earlier by 4-5 days. By the late stage of fermentation (eighth day), DT1 had a few long, thin filaments indicating some secondary growth, whereas UV-85 showed a compact pellet form of mycelia. Most mycelia of UV-18-57 still appeared intact.

Fabrication of nanoscale three-dimensional graphite stacked-junctions by focused-ion-beam and observation of anomalous transport characteristics

Venugopal, Gunasekaran,Jung, Myung-Ho,Suemitsu, Maki,Kim, Sang-Jae Elsevier 2011 Carbon Vol.49 No.8

<P><B>Abstract</B></P><P>We report on the fabrication and transport characteristics of nanoscale stacked-junctions of thin graphite flake. The stacked-junctions were fabricated using a three-dimensional focused-ion-beam milling. By varying the effective in-plane area down to submicron scale, the stacked-junctions with in-plane area <I>A</I> (from 2 down to 0.25μm<SUP>2</SUP>) and stack height–length (from 300 to 100nm) along <I>c</I>-axis were fabricated. The nano-stack shows perfect <I>c</I>-axis transport characteristics in which we observed a semiconducting behavior for <I>T</I>>65K and metallic behavior for <I>T</I><65K. The obtained results were well fitted with the <I>c</I>-axis electrical conduction mechanism. The stack with in-plane area <I>A</I> of 0.25μm<SUP>2</SUP> showed nonlinear concave-like <I>I</I>–<I>V</I> characteristics even at 300K; however the stack with <I>A⩾</I>1μm<SUP>2</SUP> were shown an ohmic-like <I>I</I>–<I>V</I> characteristic at 300K for both low and high-current biasing. It turned into nonlinear characteristics when the temperature goes down. The observation of this anomalous transport characteristics were discussed in detail with stack capacitance calculations. The nonlinear characteristics observed at 300K for the stack with <I>A</I> of 0.25μm<SUP>2</SUP> were shown best fit with Fowler–Nordheim tunneling model.</P>

A Sectional Matrix Method for IPT Coil Shape Optimization

Venugopal Prasanth,Pavol Bauer,J.A. Ferreira 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In this paper, Neumann’s integral is evaluated for computing self-inductance using a multi-turn sectional matrix method. Analytical equations are derived considering the increase in dimensions of the coil due to an impinging air-gap between the turns. The resulting sectional self-inductance matrix is computed and the concepts of sectional partial self-inductance and sectional partial mutual inductance are introduced. The effects of the various partial inductances are considered as a function of the air-gap, dimensions and turns. Further, the mutual inductance of a pair of coils is considered and the coupling is obtained analytically. The coils considered are to be used for shape optimization of IPT coils. Finally, the results are compared with experimentation. This technique being generic can be applied to a number of different polygonal shapes and can be further simplified by the theory of vector decomposition of current elements. A case study with self-inductance and perimeter as optimization objective is considered.

Expression Pattern of Matrix Metalloproteinases in Alcohol- and Thermally Oxidized Sunflower Oil-Induced Toxicity: Protective Role of an Aminothiazole Derivative

Venugopal P. Menon,Rajagopalan Rukkumani,Penumathsa Suresh Varma,Kode Aruna 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.2

The matrix metalloproteinases (MMPs) are a family of secreted and membrane-bound zinc endopeptidases.Collectively, these enzymes can degrade all of the components of the extracellular matrix including collagen, fibronectin,laminin, and basement membrane glycoproteins. Regulation in expression and activation of proteinases is one of the most im-portant mechanisms in organ morphogenesis. Fibrosis is a dynamic pathological process with a net accumulation of extra-cellular matrix proteins. In the present communication, we have investigated the changes that occur in the activity of liverMMPs in normal and in pathological conditions. The activity of MMPs was increased in thermally oxidized sunflower oil-and alcohol-treated groups, whereas the activity was decreased in the thermally oxidized oil. alcohol-fed group when com-pared with the normal control group. The activity was positively modulated when dendrodoine analogue [4-amino-5-benzoyl-2(4-methoxyphenylamino)thiazole] was administered along with ethanol and thermally oxidized oil, which indicates the pro-tective effect of this drug.

Modulatory Effects of Curcumin and Curcumin Analog on Circulatory Lipid Profiles During Nicotine-Induced Toxicity in Wistar Rats

Venugopal P. Menon,K.N. Rajasekharan,C. Kalpana 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.2

Nicotine, a major toxic component of cigarette smoke, plays a key role in the development of cardiovascular disease and lung cancer. In the present study, we have synthesized an analog of curcumin and biomonitored its influence over biochemical marker enzymes and lipid profiles on nicotine-induced toxicity in Wistar rats. The effects were compared with that of curcumin, a well-known antioxidant and anti-hyperlipidemic agent. Toxicity was induced by subcutaneous injection of nicotine at a dose of 2.5 mg/kg of body weight (5 days a week, for 22 weeks), and curcumin (80 mg/kg) was given simultaneously along with nicotine by intragastric intubation for 22 weeks. Measurements of activities of the biochemical marker enzymes aspartate transaminase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase and of plasma lipid profiles were used to monitor the anti-hyperlipidemic effects of curcuminoids. In nicotine-treated rats, enhanced plasma marker enzymes and lipid profiles were observed. Administration of curcumin or curcumin analog to nicotine-treated rats significantly reduced the activity of marker enzymes and plasma lipid levels. Thus, our findings suggest that curcumin and its analog exert an anti-hyperlipidemic effect against nicotine-induced lung toxicity and may be a promising agent for treatment of hyperlipidemia and atherosclerosis

Effect of Photo-Irradiated Curcumin Treatment Against Oxidative Stress in Streptozotocin-Induced Diabetic Rats

Venugopal P. Menon,M. Sri Balasubashini,T. Mahesh 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.2

Increasing evidence in both experimental and clinical studies suggests that oxidative stress plays a major rolein the pathogenesis of diabetes mellitus. Although phenolic compounds attenuate oxidative stress-related damage, there areconcerns over toxicity of synthetic phenolic antioxidants, and this has considerably stimulated interest in investigating the roleof natural phenolics in medicinal application. In the present study, we examined the effect of photo-irradiated curcumin inexperimental diabetes to evaluate the anti-hyperglycemic properties of this compound on streptozotocin (40 mg/kg of bodyweight)-induced diabetes. Photo-irradiated curcumin was given at a dose of 10 or 30 mg/kg of body weight. The level ofblood glucose was elevated in diabetic animals. Circulatory lipid peroxidation, vitamin C, vitamin E, and enzymic antioxi-dants such as superoxide dismutase and catalase were analyzed. The antioxidant status decreased in diabetic animals. Oral ad-ministration of photo-irradiated curcumin for 45 days resulted in a significant decrease in the levels of blood glucose alongwith near-normalization of the enzymic activities and the levels of lipid peroxidative markers. The most effective results wereobtained on treatment with 30 mg/kg of body weight of photo-irradiated curcumin.

Self-assembled hollow mesoporous Co3O4 hybrid architectures: a facile synthesis and application in Li-ion batteries

Venugopal, N.,Lee, D. J.,Lee, Y.,Sun, Y. K. Royal Society of Chemistry 2013 Journal of materials chemistry. A, Materials for e Vol.1 No.42

Comparative Effects of Curcumin and Its Analog on Alcohol- and Polyunsaturated Fatty Acid-Induced Alterations in Circulatory Lipid Profiles

Venugopal P. Menon,Kode Aruna,Penumathsa Suresh Varma,Kallikat Narayanan Rajasekaran,Rajagopalan Rukkumani 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.2

Excessive alcohol intake induces hyperlipidemia. Studies suggest that natural principles and their analogs are known to possess anti-hyperlipidemic properties. In the present work we tested the effect of curcumin, an active principle of turmeric (Curcuma longa), and a curcumin analog on alcohol- and thermally oxidized polyunsaturated fatty acid (PUFA)- induced hyperlipidemia. Male albino Wistar rats were used for the experimental study. Anti-hyperlipidemic activity of curcumin and curcumin analog was evaluated by analyzing the levels of cholesterol, triglycerides (TGs), phospholipids (PLs), and free fatty acids (FFAs). The results showed that the levels of cholesterol, TGs, PLs, and FFAs were increased significantly in alcohol-, PUFA-, and alcohol PUFA-treated groups, which were brought down significantly on treatment with either of the curcuminoids. Curcumin analog treatment was found to be more effective than curcumin treatment. From the results obtained, we conclude that both curcumin and its analog effectively protect the system against alcohol- and PUFA-induced hyperlipidemia and are possible candidates for the treatment of hyperlipidemia.

Fabrication and Characteristics of Submicron Stacked-Junctions on Thin Graphite Flakes

Venugopal, Gunasekaran,Kim, Sang-Jae American Scientific Publishers 2011 Journal of Nanoscience and Nanotechnology Vol.11 No.2

<P>We report on the fabrication and transport characteristics of submicron-size stacks along c-axis of thin graphite flakes. The stacks were fabricated using a three-dimensional focused-ion-beam (FIB) etching technique. The stack with in-plane area A of 0.5 microm2 showed nonlinear concave-like I-V characteristics even at 300 K; however the stack with A of > 0.5 microm2 were shown an ohmic-like I-V characteristic at 300 K for both low and high-current biasing. It turned into nonlinear characteristics when the temperature goes down. The in-plane area dependence of stack capacitance were discussed and the observed capacitance of stack with A of 0.5 microm2 is smaller than the capacitance of stack with A of 1 microm2 which causes the nonlinear I-V characteristics in stack with A of 0.5 microm2 even at 300 K.</P>

Hybrid Cascaded MLI topology using Ternary Voltage Progression Technique with Multicarrier Strategy

Venugopal, Jamuna,Subarnan, Gayathri Monicka The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

A major problem in conventional multilevel inverter is that an increase in power semiconductor switches causes an increase in cost and switching losses of the inverter. The multicarrier strategy adopted for the multilevel inverters has become more popular due to reduced cost, lower harmonic distortion, and higher voltage capability than the conventional switching strategy applied to inverters. Various topologies and modulation strategies have been reported for utility and drive applications. Level shifted based pulse width modulation techniques are proposed to investigate the performance of the multilevel inverter. The proposed work focuses on reducing the utilized switches so that the cost and the switching losses of the inverter do not go up and the consistent efficiency could be achieved. This paper presents the detailed analysis of these topologies. The analysis is based on the number of switches, DC sources, output level, maximum voltage, and the efficiency. As an illustration, single phase cascaded multilevel inverter topologies are simulated using MATLAB/SIMULINK and the experimental results demonstrate the viability of these inverters.