Existence of Partially Degenerate Electrical Transport in Intermetallic Cu2SnSe3 Thermoelectric System Sintered at Different Temperatures

K. Gurukrishna,H. R. Nikhita,S. M. Mallikarjuna Swamy,Ashok Rao 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

A detailed investigation on the temperature dependent electrical properties of Cu2SnSe3system, synthesized via conventionalsolid-state reaction at different sintering temperatures are presented in this communication. All the samples exhibit degeneratesemiconducting nature at low temperatures. The existence of small polarons and hence electron–phonon interactionsare confirmed at temperatures below 400 K. A transition was observed from degenerate to non-degenerate semiconductingbehaviour at high temperatures (T > 400 K). The study confirms the unusual transition in electrical resistivity as well asthermopower at high temperatures in all the compounds, demonstrating the existence of minority carrier excitation alongwith temperature-triggered ionisation of the defects. The transport behaviour is further supported by an upward movementof Fermi level away from the valence band. Highest weighted mobility of 8.2 cm2V−1 s−1 at 673 K was obtained for thesample sintered at 1073 K. A considerable decrease in electrical resistivity with increase in temperature (T > 400 K) hasdriven the power factor to increase exponentially, thereby achieving highest value of 188 μV/mK2 (at 673 K) for the samplesintered at 673 K.

Immobilization of Xylanase Using a Protein-Inorganic Hybrid System

( Ashok Kumar ),( Sanjay K. S. Patel ),( Bharat Mardan ),( Raviteja Pagolu ),( Rowina Lestari ),( Seong-hoon Jeong ),( Taedoo Kim ),( Jung Rim Haw ),( Sang-yong Kim ),( In-won Kim ),( Jung-kul Lee ) 한국미생물생명공학회(구 한국산업미생물학회) 2018 Journal of microbiology and biotechnology Vol.28 No.4

In this study, the immobilization of xylanase using a protein-inorganic hybrid nanoflower system was assessed to improve the enzyme properties. The synthesis of hybrid xylanase nanoflowers was very effective at 4°C for 72 h, using 0.25 mg/ml protein, and efficient immobilization of xylanase was observed, with a maximum encapsulation yield and relative activity of 78.5% and 148%, respectively. Immobilized xylanase showed high residual activity at broad pH and temperature ranges. Using birchwood xylan as a substrate, the V_max and K_m values of xylanase nanoflowers were 1.60 mg/ml and 455 μmol/min/mg protein, compared with 1.42 mg/ml and 300 μmol/min/mg protein, respectively, for the free enzyme. After 5 and 10 cycles of reuse, the xylanase nanoflowers retained 87.5% and 75.8% residual activity, respectively. These results demonstrate that xylanase immobilization using a proteininorganic hybrid nanoflower system is an effective approach for its potential biotechnological applications.

Characteristic enhancement of white LED lamp using low temperature co-fired ceramic-chip on board package

심재관,K. Ashok,라용호,임홍철,백병준,이철로 한국물리학회 2012 Current Applied Physics Vol.12 No.2

In this paper, we propose low temperature co-fired ceramic-chip on board (LTCC-COB) package with improved thermal characteristics; no insulation layer exists between the LED chip and metal base. In actual measurement as well as in thermal simulation, the proposed LED lamp structure showed excellent thermal properties, compared with surface mound device-printed circuit board (SMD-PCB) package LED lamp. The optical output power, thermal distribution, currentevoltage (IeV) and electroluminescence (EL) were measured and compared to analyze the characteristics of LTCC-COB package LED lamp with SMD-PCB package LED lamp. EL peak intensity of LTCC-COB package LED lamp is 1.75 times better than that of SDM-PCB package LED lamp. The thermal resistance between packing area and air was found to be 7.3 K/W and 7.9 K/W for LTCC-COB package and SMD-PCB package respectively. The proposed LTCCCOB packaged LED lamp is not only suitable for high power LED package due to its low thermal resistance but also a promising solution for illumination modules.

Characteristic enhancement of white LED lamp using low temperature co-fired ceramic-chip on board package

Sim, J.K.,Ashok, K.,Ra, Y.H.,Im, H.C.,Baek, B.J.,Lee, C.R. Elsevier 2012 Current Applied Physics Vol.12 No.2

In this paper, we propose low temperature co-fired ceramic-chip on board (LTCC-COB) package with improved thermal characteristics; no insulation layer exists between the LED chip and metal base. In actual measurement as well as in thermal simulation, the proposed LED lamp structure showed excellent thermal properties, compared with surface mound device-printed circuit board (SMD-PCB) package LED lamp. The optical output power, thermal distribution, current-voltage (I-V) and electroluminescence (EL) were measured and compared to analyze the characteristics of LTCC-COB package LED lamp with SMD-PCB package LED lamp. EL peak intensity of LTCC-COB package LED lamp is 1.75 times better than that of SDM-PCB package LED lamp. The thermal resistance between packing area and air was found to be 7.3 K/W and 7.9 K/W for LTCC-COB package and SMD-PCB package respectively. The proposed LTCC-COB packaged LED lamp is not only suitable for high power LED package due to its low thermal resistance but also a promising solution for illumination modules.

Investigations on magnetic and electrical properties of Zn doped Fe₂O₃ nanoparticles and their correlation with local electronic structures

Kumar, Parmod,Sharma, Vikas,Singh, Jitendra P.,Kumar, Ashish,Chahal, Surjeet,Sachdev, K.,Chae, K.H.,Kumar, Ashok,Asokan, K.,Kanjilal, D. Elsevier 2019 Journal of magnetism and magnetic materials Vol.489 No.-

<P><B>Abstract</B></P> <P>Present work aims at investigating the structural, magnetic and dielectric properties of zinc doped Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles (pure, 10%, 20% & 30%) and correlated with their local electronic structures using X-ray absorption near-edge structure (XANES) spectroscopy. X-ray diffraction and Raman measurements infer that doping of Zn cations lead to the formation of secondary phases corresponding to ZnFe<SUB>2</SUB>O<SUB>4</SUB> along with the hematite phase of Fe<SUB>2</SUB>O<SUB>3</SUB>. Magnetic measurements show that magnetization vs magnetic field curve for 10% Zn doping exhibit maximum saturation magnetization (~2.93 × 10<SUP>−3</SUP> emu/g) as well as the coercivity (~956 Oe). The values of these parameters decrease for higher content of Zn. The temperature dependence of dielectric behaviour follows the same trend as that of the lattice parameter and magnetic measurements. The XANES spectra at Fe L- and Fe K-edges indicate partial reduction of Fe<SUP>3+</SUP> ions into Fe<SUP>2+</SUP> upon Zn doping in the Fe<SUB>2</SUB>O<SUB>3</SUB> lattice. However, divalent state is favourable for Zn (i.e. Zn<SUP>2+</SUP>) within the doping range reported in this study.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Zn doped Fe<SUB>2</SUB>O<SUB>3</SUB> nanoparticles. </LI> <LI> Study of magnetic and electrical properties. </LI> <LI> Correlation of magnetic and electrical properties with local electronic structure. </LI> </UL> </P>

Effect of Dietary Fiber Enrichment and Different Cooking Methods on Quality of Chicken Nuggets

Ashok K. Pathera,C. S. Riar,Sanjay Yadav,D. P. Sharma 한국축산식품학회 2017 한국축산식품학회지 Vol.37 No.3

The effect of dietary fiber enrichment (wheat bran) and cooking methods (oven, steam and microwave) on functional and physico-chemical properties of raw nuggets formulation as well as nutritional, color and textural properties of chicken nuggets were analyzed in this study. Among different cooking methods used for nuggets preparation, steam cooked nuggets had significantly (p<0.05) higher water holding capacity (56.65%), cooking yield (97.16%) and total dietary fiber content (4.32%) in comparison to oven and microwave cooked nuggets. The effect of cooking methods and wheat bran incorporation was also noticed on textural properties of the nuggets. Hardness, firmness and toughness values of oven and steam cooked nuggets were significantly (p<0.05) higher than microwave cooked nuggets. Among nuggets prepared by different cooking methods, cohesiveness of microwave cooked nuggets was found to be significantly (p<0.05) highest, whereas, oven cooked nuggets had significantly (p<0.05) highest gumminess and chewiness values. Steam cooked nuggets were found to be better among all nuggets due to their higher cooking yield and dietary fiber content.

Anti-Inflammatory Potency of Nano-Formulated Puerarin and Curcumin in Rats Subjected to the Lipopolysaccharide-Induced Inflammation

Ashok K. Singh,Yin Jiang,Shveta Gupta,Mohamod Younus,Mohamod Ramzan 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.10

Puerarin (PU) and curcumin (CU), used commonly in traditional Chinese medicine and Ayurveda, have been shown to possess potent anti-inflammatory, anti-oxidation, and neuro-protective properties. Despite the experimental success of CU and PU in in vitro and animal models, their effectiveness has not yet been demonstrated in clinical trials, possibly because of their poor bioavailability. We hypothesized that gold nanoparticle (AuNP)-formulated PU (PU-AuNP), CU (CUAuNP), or a combination of PU and CU (PU-CU-AuNP) were a more effective and nontoxic alternative to their bulk (nonformulated) counterparts. To test the hypothesis, bioavailability, therapeutic potency, and toxicity of bulk CU and/or PU were compared with those of their nanotized counterparts in rats subjected to the lipopolysaccharide (LPS)-induced inflammation. This study showed that a 20-mg/kg dose of bulk PU or a mixture of PU and CU did not, while their nanotized counterparts, PU-AuNP, CU-AuNP, or PU-CU-AuNP, effectively suppressed the LPS-induced inflammation and cytotoxicity in rats. In addition, PU-CU-AuNP was more potent than PU-AuNP or CU-AuNP alone. The blank AuNP (bAuNP) at £ 40 mg/kg dose did not cause any adverse effects (blood and brain lactic acid concentrations, kidney function, and neuronal apoptosis were measured) in animals. Therefore, the present observations suggest that a bi-functional AuNP loaded with CU and PU may effectively suppress the LPS-induced inflammation and cytotoxicity provided the following conditions are met: (1) The AuNP dose is at or below the no-effect dose; (2) the nanoparticles release a therapeutic dose of CU and PU in vivo; and (3) the active ingredients are released into the intracellular component of the brain.

Antifungal Activity of Securinine against Some Plant Pathogenic Fungi

Ashok K. Singh,M. B. Pandey,Sarita Singh,Anil K. Singh,U. P. Singh The Korean Society of Mycology 2008 Mycobiology Vol.36 No.2

Indian Space Program and Design Methodology for Higher Payload Class of Rockets

Ashok K. Bakshi 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.12

Corelational Study of Liver Enzyme, Vitamin D and Probability of Liver Disease: A Cross Sectional Study

( Ashok K. Sah ),( M. V. Simha ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1

Aims: To investigate the relationship between liver enzyme, vitamin D status, and occurrences liver disease. Methods: We incorporated a total of 545 cases from hospital studies completed in 2018-2019. Serumenzymes such as aspartate transaminase (AST)serum alanine transaminase (ALT), and gamma-glutamyl transferase (GGT) were measured as minimum basic assess and vitamin D status as measured by serum 25-hydroxyvitamin. Information on the patients (fetal and nonfetal liver disease) was collected from the patients’ family and relatives by follow up method. Results: Multivariable Cox regression analyses with age as underlying time axis and delayed entry showed a statistically significant inverse association between vitamin D status and incident liver disease with a hazard ratio = 0.78 (95% confidence interval 0.69-0.89) per 10 nmol/l higher vitamin D status at baseline (adjusted for season, gender, smoking, alcohol consumption, physical activity, dietary habits, education, body mass index, and ALT). The risk of having a high level of ALT, AST, or GGT tended to be higher for lower vitamin D levels, although not statistically significant. Conclusions: In this study, the vitamin D status and incidence of liver disease are inversely proportional to each other. Further studies are required to know whether the patients are at risk of developing impaired liver disease due to vitamin D deficiency.