Effect of illumination on hydrogenated amorphous silicon thin films doped with chalcogens

Sharma, S.K.,Kumar, K.N.P.,Kang, K.J.,Mehra, R.M. North-Holland 2009 Journal of non-crystalline solids Vol.355 No.31

Hydrogenated amorphous silicon thin films doped with chalcogens (Se or S) were prepared by the decomposition of silane (SiH<SUB>4</SUB>) and H<SUB>2</SUB>Se/H<SUB>2</SUB>S gas mixtures in an RF plasma glow discharge on 7059 corning glass at a substrate temperature 230<SUP>o</SUP>C. The illumination measurements were performed on these samples as a function of doping concentration, temperature and optical density. The activation energy varied with doping concentration and is higher in Se-doped than S-doped a-Si:H thin films due to a low defect density. From intensity versus photoconductivity data, it is observed that the addition of Se and S changes the recombination mechanism from monomolecular at low doping concentration films to bimolecular at higher doping levels. The photosensitivity (σ<SUB>ph</SUB>/σ<SUB>d</SUB>) of a-Si,Se:H thin films decreases as the gas ratio H<SUB>2</SUB>Se/SiH<SUB>4</SUB> increased from 10<SUP>-4</SUP> to 10<SUP>-1</SUP>, while the photosensitivity of a-Si,S:H thin films increases as the gas ratio H<SUB>2</SUB>S/SiH<SUB>4</SUB> increased from 6.8x10<SUP>-7</SUP> to 1.0x10<SUP>-4</SUP>.

Effect of Triticale Dried Distillers Grains with Solubles on Ruminal Bacterial Populations as Revealed by Real Time Polymerase Chain Reaction

Wu, R.B.,Munns, K.,Li, J.Q.,John, S.J.,Wierenga, K.,Sharma, R.,Mcallister, T.A. Asian Australasian Association of Animal Productio 2011 Animal Bioscience Vol.24 No.11

Real time PCR was used in this study to determine the effect of triticale dried distillers grains with solubles (TDDGS) as a replacement for grain or barley silage in finishing diets on the presence of six classical ruminal bacterial species (Succinivibrio dextrinosolvens, Selenomonas ruminantium, Streptococcus bovis, Megasphaera elsdenii, Prevotella ruminicola and Fibrobacter succinogenes) within the rumen contents of feedlot cattle. This study was divided into a step-wise adaptation experiment (112 days) that examined the effects of adaptation to diets containing increasing levels of TDDGS up to 30% (n = 4), a short-term experiment comparing animals (n = 16) fed control, 20%, 25% or 30% TDDGS diets over 28 days, and a rapid transition experiment (56 days) where animals (n = 4) were rapidly switched from a diet containing 30% TDDGS to a barley-based diet with no TDDGS. It was found that feeding TDDGS as replacement for barley grain (control vs. 20% TDDGS) decreased 16S rRNA copy numbers of starch-fermenting S. ruminantium and S. bovis (p<0.001 and p = 0.04, respectively), but did not alter 16S rRNA copy numbers of the other rumen bacteria. Furthermore, feeding TDDGS as a replacement barley silage (20% vs. 25% and 30% TDDGS) increased 16S rRNA copy numbers of S. ruminantium, M. elsdenii and F. succinogenes (p<0.001; p = 0.03 and p<0.001, respectively), but decreased (p<0.001) the 16S rRNA copy number of P. ruminicola. Upon removal of 30% TDDGS and return to the control diet, 16S rRNA copy numbers of S. ruminantium, M. elsdenii and F. succinogenes decreased (p = 0.01; p = 0.03 and p = 0.01, respectively), but S. dextrinosolvens and S. bovis increased (p = 0.04 and p = 0.009, respectively). The results suggest that replacement of TDDGS for grain reduces 16S rRNA copy numbers of starch-fermenting bacteria, whereas substitution for barley silage increases 16S rRNA copy numbers of bacteria involved in fibre digestion and the metabolism of lactic acid. This outcome supports the contention that the fibre in TDDGS is highly fermentable.

Investigation on the local electronic/atomic structure properties using XANES/EXAFS and photocatalyst application of Zr_1-xCu_xO₂ (0 @? x @? 0.2)

Sharma, A.,Varshney, M.,Chae, K.H.,Shin, H.J.,Won, S.O. Elsevier 2016 Current Applied Physics Vol.16 No.10

<P>We investigated local electronic/atomic structure properties by using X-ray absorption spectroscopy and demonstrated the photocatalyst application of Zr1-xCuxO2 (0 <= x <= 0.2) samples. X ray diffraction (XRD) results revealed the amorphous nature of the samples; however, transmission electron microscopy (TEM) depicted the formation of < 2 nm sized particles in all of the samples. Local electronic structure was investigated by X-ray absorption near edge structure (XANES) at O K-edge, Zr K-edge and Cu K-edge. The O K-edge XANES suggested strong hybridization of s-p-d orbitals upon Cu doping. The Cu K-edge XANES confirmed +1 valence state of Cu (Cu+1) in all of the Cu doped ZrO2 samples. Extended X-ray absorption fine structure (EXAFS) analysis at the Zr K-edge nullifies the formation of trivial phases and confirms the local monoclinic structure in all of the samples. Photocatalyst properties of the samples were investigated by monitoring the net degradation in the methyl orange dye aqueous solution under the UV light irradiation. The Cu doped ZrO2 samples exhibited superior photo-catalyst properties over the undoped ZrO2. (C) 2016 Elsevier B.V. All rights reserved.</P>

Characterization of dihydrolipoamide dehydrogenase from the mitochondria of Helicoverpa armigera, a pest resistant to insecticides

S. Md. AKBAR,S. K. JAYALAKSHMI,H. C. SHARMA,K. SREERAMULU 한국곤충학회 2011 Entomological Research Vol.41 No.6

Dihydrolipoamide dehydrogenase (DHLDH) was isolated from the mitochondria of Helicoverpa armigera, a destructive pest which has developed resistance to commonly used insecticides. The flavoenzyme was purified 17.98-fold to homogeneity with an overall yield of 10.53% by employing ammonium sulfate precipitation, hydroxylapatite chromatography and CM-Sephadex chromatography. The purified enzyme exhibited the specific activity of 18.7 U/mg and was characterized as a dimer with a subunit mass of 66 kDa. The enzyme showed specificity for nicotinamide adenine dinucleotide – hydrogen (NADH) and lipoamide, as substrates, with Michaelis-Menten constants (K_m) of 0.083 mmol/L and 0.4 mmol/L, respectively. The reduction reaction of lipoamide by the enzyme could be explained by ping-pong mechanism. The spectra of DHLDH showed the maximum absorbance at 420 nm, 455 nm and 475 nm. The enzyme activity was strongly inhibited by mercurial and arsenical compounds. The N-terminal sequence of Ha-DHLDH showed homology with those of mammalian and arthropod DHLDH. Since H. armigera has developed high levels of resistance to commonly used insecticides, biochemical properties of the metabolic enzymes such as DHLDH, could be helpful to develop insecticidal molecules for the control of H. armigera, with a different mode of action.

Comparative analysis of VMT genes/proteins in selected plant species with emphasis on bread wheat (Triticum aestivum L.)

Sharma Hemant,Shayaba,Kumar Rahul,Kumar Jitendra,Bhadana Deepa,Batra Ritu,Singh Rakhi,Kumar Sachin,Roy Joy K,Balyan Harindra S.,Gupta Pushpendra K. 한국유전학회 2023 Genes & Genomics Vol.45 No.11

Background In recent years, the study of molecular basis of uptake, transport and utilization of grain Fe/Zn (GFe/GZn) in wheat has been an active area of research. As a result, it has been shown that a number of transporters are involved in uptake and transport of Fe. In a recent study, knockout of a transporter gene OsVMT (VACUOLAR MUGINEIC ACID TRANSPORTER) in rice was shown to be involved in Fe homoeostasis. Objective In this study, we analysed VMT genes among six monocots and three dicots with major emphasis on wheat VMT genes (TaVMTs), taking OsVMT gene as a reference. Methods and results Using OsVMT gene as a reference, VMT genes were identified and sequence similarities were examined among six monocots and three dicots. Each VMT protein carried one functional domain and 7 to 10 distinct motifs (including 9 novel motifs). The qRT-PCR analysis showed differential expression by all the six TaVMT genes in pairs of contrasting wheat genotypes with high (FAR4 and WB02) and low (K8027 and HD3226) GFe/GZn at two different grain filling stages (14 DAA and 28 DAA). TaVMT1 genes showed up-regulation in high GFe/Zn genotypes relative to low GFe/Zn genotypes, whereas the TaVMT2 genes showed down-regulation or nonsignificant up-regulation in a few cases. Conclusions At 14 DAA, each of the six TaVMT genes exhibited higher expression in wheat genotypes with high GFe and GZn relative to those with low GFe and GZn, suggesting major role of VMT genes in improvement of grain Fe/Zn homoeostasis, thus making TaVMT genes useful for improvement in Fe/Zn in wheat grains.

X-ray absorption spectroscopy investigations on electronic structure and luminescence properties of Eu:SnO₂-SnO nanocomposites

Sharma, A.,Varshney, M.,Shin, H.J.,Chae, K.H.,Won, S.O. Elsevier 2016 CURRENT APPLIED PHYSICS Vol.16 No.10

<P>Tin oxide nanostructures are nontoxic in nature and biocompatible. However, they exhibit weak emission characteristics that limit their applications in cellular and biology fields. Therefore, it is important to enhance luminescence properties in this oxide and establish a relationship between the local electronic structure and emission characteristics. In this report, we demonstrate significant advancement in the photoluminescence (PL) properties in the Eu incorporated SnO2-SnO nanocomposites. Eu: SnO2-SnO nanocomposites were synthesized by chemical precipitation method. X-ray diffraction (XRD), X-ray absorption near edge structure (XANES) and PL measurements were performed to investigate the structural, electronic structure and emission properties of the samples. Eu3+ ions, as confirmed by the Eu M-5,M-4-edge XANES studies, lead to defect formation and local electronic structural perturbation in the nanocomposites. The O K-edge and Sn M-5,M-4-edge XANES studies confirm a net decrease in the hybridization of O 2p and Sn 5s/5p states and formation of Sn defects, upon Eu doping. Significant enhancement in the Eu3+ related interband transitions (D-5(0)-F-7(J); J = 0,1,2,3,4) is achieved upon increasing the Eu concentrations, indicating synthesis of emission characteristic rich SnO2-SnO nanocomposites. (C) 2016 Elsevier B.V. All rights reserved.</P>

Tourism in Maldives

S,C,Bagri,S,K,Gupta,Reena Sharma 세계문화관광학회 2009 Conference Proceedings Vol.10 No.0

The paper includes the growth of tourism since years in Maldives. The paper examines tourist development in Maldives. This will include the tourism indicators and impacts of tourism economically, socially and culturally. Although social/cultural impacts from coastal tourism development have been widely recognized in a great number of cases, it is relatively, difficult to develop technical criteria, for evaluating these impacts in quantitative terms. According to the Ministry of Tourism website, the emergence of tourism in 1972 transformed the economy of the Maldives, moving rapidly from the dependence on the fisheries sector to the tourism sector. Just in three and a half decades, the industry has become the main source of income and livelihood of the people of the Maldives. Tourism is also the country's biggest foreign currency earner and the single largest contributor to the GDP. Today, there are 89 resorts in the Maldives with a bed capacity of over 17,000, providing world class facilities for tourists whose annual arrival figure exceeds 600,000.

Biogenerated silica nanoparticles synthesized from sticky, red, and brown rice husk ashes by a chemical method

Sankar, S.,Sharma, S.K.,Kaur, N.,Lee, B.,Kim, D.Y.,Lee, S.,Jung, H. Ceramurgica ; Elsevier Science Ltd 2016 CERAMICS INTERNATIONAL Vol.42 No.4

An inexpensive chemical method was used to synthesize biogenic mesoporous silica (m-SiO<SUB>2</SUB>) from rice husk ash (RHA). A comparative study was carried out to produce silica nanoparticles (S-SiO<SUB>2</SUB>, R-SiO<SUB>2</SUB>, and B-SiO<SUB>2</SUB>) from three type of rice husk ashes (sticky, red, and brown). The microstructure of m-SiO<SUB>2</SUB> was dependent on the geographical provenance and the types of RHA. An analysis of the SEM and TEM micrographs reveals that the S-SiO<SUB>2</SUB> nanoparticles had a clustered spherical shape, while R-SiO<SUB>2</SUB> and B-SiO<SUB>2</SUB> nanoparticles were found to be purely spherical. The average crystallite size of S-SiO<SUB>2,</SUB> R-SiO<SUB>2</SUB> and B-SiO<SUB>2</SUB> nanoparticles evaluated from the TEM measurements were observed to be 50, 20 and 10nm, respectively. The XRD pattern of silica nanopowders had an absence of sharp peaks that confirmed the amorphous nature of the material. The Fourier transform infrared (FTIR) spectra of silica nanoparticles showed the symmetric Si-O and O-Si-O stretching bond vibrations at 462, 1088, and 1098cm<SUP>-1</SUP>. The surface area of S-SiO<SUB>2,</SUB> R-SiO<SUB>2</SUB> and B-SiO<SUB>2</SUB> nanopowders was measured to be 7.5513, 201.45, and 247.18m<SUP>2</SUP>g<SUP>-1</SUP>, respectively. The surface area of uniformly-distributed spherical nanoparticles of B-SiO<SUB>2</SUB> was observed the highest, which can be applied for the application of energy storage and drug delivery systems.

Rapid thermal annealing induced modification in structural and electronic structure properties of Ti_0.95Co_0.05O_2@?δ thin films

Rodrigues, E.C.,Sharma, S.K.,de Menezes, A.S.,Chae, K.H.,Gautam, S.,Aljawf, R.N.,Kumar, S. Pergamon Press 2016 Materials research bulletin Vol.83 No.-

Thin film of Ti<SUB>0.95</SUB>Co<SUB>0.05</SUB>O<SUB>2-δ</SUB> was deposited on Si (100) using PLD method and annealed in O<SUB>2</SUB> and N<SUB>2</SUB> environment. Raman spectra confirm that all the films have rutile structure. Surface morphology indicates that the surface roughness and grain size increase with annealing. The electronic structure studied by NEXAFS spectroscopy at O K, Ti L<SUB>3,2</SUB> and Co L<SUB>3,2</SUB>-edges revealed that peak intensities decrease significantly for the film annealed N<SUB>2</SUB> environment. The ligand-field splitting estimated from the energy difference between the t<SUB>2g</SUB> and e<SUB>g</SUB> features in O K-edge spectra were 2.71eV for as-deposited and O<SUB>2</SUB> annealed film, whereas reduced more than double (@?1.32eV) for the film annealed in N<SUB>2</SUB>. Atomic multiplet calculations and experimentally observed NEXAFS spectra at Co L<SUB>3,2</SUB>-edge and Ti L<SUB>3,2</SUB>-edge confirm that Co present in 2+ and Ti in +4 valence state, whereas the multiplet structures of O<SUB>2</SUB> annealed film looks similar to Co metal.

Ferromagnetism in Chemically-synthesized Co-doped ZnO

샤런드라쿠마르,Y. J. Kim,B. H. Koo,최희규,이찬규,S. K. Sharma,M. Knobel,S. Gautam,K. H. Chae 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.3

We report room temperature ferromagnetism (RTFM) in Co-doped ZnO (Zn1−xCoxO; x = 0.01 − 0.05) powder synthesized using a co-precipitation method. Our magnetometry data reveal a weak FM behavior at RT in the range 0.01 < x < 0.05. FM by magnetic FM moment steadily decreases with increasing dopant. The O K-edge near-edge X-ray absorption fine structure (NEXAFS) spectra indicate that O vacancies increases with increasing Co concentration and that the sample with x ≥ 0.03 has more broadening at 535 and 540 eV, which may be due to the oxygen vacancies. Co in the ZnO host reveals a +2 oxidation state via the K edge NEXAFS spectra.