Silicon-Nanocrystal-Coated Silica Microsphere Thermooptical Switch

Tewary, Anuranjita,Digonnet, Michel J. F.,Sung, Joo-Yeon,Shin, Jung H.,Brongersma, Mark L. IEEE 2006 IEEE journal on selected topics in quantum electro Vol.12 No.6

<P>We report on a low-switching-energy, all-optical fiber switch that consists of a silica microsphere resonator coated with a silica layer containing silicon nanocrystals. A signal at 1450 nm and a pump at 488 nm are coupled into the microsphere through a tapered fiber. When a pump pulse is launched into the sphere, it is absorbed by the nanocrystal layer, causing the sphere to heat up and change its refractive index. The index change can be exploited to switch the signal by shifting the microsphere resonance. A resonance wavelength shift of 5 pm, sufficient to fully switch the signal, was observed with a pump pulse energy of only 85 nJ. The rise time of the switch was ~25 ms (limited by the pump peak power) and its fall time was ~30 ms (limited by the sphere's thermal time constant). The product of the switching peak power (3.4 mu W) and the device's characteristic dimension (a diameter of 150 mum) is 5.1times10<SUP>-10</SUP> Wm, one of the lowest values reported for an all-optical fiber switch</P>

Cavity <tex> $Q$</tex> Measurements of Silica Microspheres with Nanocluster Silicon Active Layer

Sung, Joo-Yeon,Tewary, Anuranjita,Brongersma, Mark L.,Shin, Jung H. IEEE 2006 IEEE journal of selected topics in quantum electro Vol.12 No.6

<P>In this paper, the effect of the nanocluster-silicon (nc-Si) active layer on the cavity Q of silica microspheres is investigated. The silicon-rich silicon oxide (SRSO) (140plusmn10 nm thick) films with excess Si content ranging from 5 to 14 at.% were deposited on the silica microspheres formed by the CO<SUB>2</SUB> laser melting of an optical fiber, and subsequently annealed at temperatures ranging from 650degC to 1100 degC. The cavity Q of the spheres with the active layer was measured at 1.56 mum using a tunable external cavity coupled laser diode and a tapered fiber coupling. We find that the presence of the nc-Si active layer reduces the Q value of the microsphere from ges 2times10<SUP>7</SUP> to (2-5) times10<SUP>5</SUP>. However, we found no correlation between the formation, size, and density of the nc-Si and the cavity Q-factor, indicating that the scattering by the nc-Si does not present the dominant optical loss mechanism in the SRSO film</P>

Influence of forestry host plants and rearing seasons on silk gland weight of tropical tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) under Doon valley conditions of Uttarakhand in India

( Narendra Kumar Bhatia ),( Mohd. Yousuf ),( Pankaj Tewary ),( Satya Prakash Sharma ) 한국잠사학회 2016 International Journal of Industrial Entomology Vol.32 No.1

Tropical tasar silkworm, Antheraea mylitta is a commercial forest silkworm in India that produces tasar silk, but never experimented in Uttarakhand, a Himalayan state of India. A. mylitta express divergent phenotypic characters under different ecological conditions; so, we studied the effect of seven forest tree species in two rearing seasons on variability in silk gland weight of Daba (bivoltine) ecorace of A. mylitta at Forest Research Institute in Dehra Dun, Uttarakhand during 2012 and 2013. We used two-way completely randomized block factorial design and Post HOC Tukey’s HSD test to analyse the collected data and there after carried out multiple regression analysis. Results indicated that silk gland weight differed significantly between rearing seasons (DF=1, F=2333.98, p <0.05), host plants (DF 6, F= 1516.25, p <0.05) and their interactions (DF=6, F=7.10, p <0.05). Higher silk gland weight was found in second rearing season than the first on all the host tree species. Terminalia alata fed A. mylitta larvae showed the highest silk gland weight of 8.03 and 9.47 g in first and second rearing seasons, followed by T. tomentosa (7.19 & 9.01g), T. arjuna (6.8 & 8.08 g) and L. speciosa (6.57 & 7.83 g) fed larvae, respectively. Post HOC Tukey’s HSD test indicated that silk gland weight of L. speciosa and T. arjuna fed larvae in both the rearing seasons did not differ significantly. E.I. analysis also confirmed that T. alata, T. tomentosa, T. arjuna and L. speciosa are better in their order of merit than T. bellirica , T. chebula and L. tomentosa. Multiple regression analysis indicates that larval weight gain is a strong predictor (β=1.002, t=346.777, p = <0.05) for the silk gland weight of A. mylitta ; however, larval duration had significant negative regression weight (β=-0.270, t=-8.436, p = <0.05) on mean weight of silk gland.

Influence of forestry host plants and rearing seasons on silk gland weight of tropical tasar silkworm, Antheraea mylitta (Lepidoptera: Saturniidae) under Doon valley conditions of Uttarakhand in India

Bhatia, Narendra Kumar,Yousuf, Mohd.,Tewary, Pankaj,Sharma, Satya Prakash Korean Society of Sericultural Science 2016 International Journal of Industrial Entomology Vol.32 No.1

Tropical tasar silkworm, Antheraea mylitta is a commercial forest silkworm in India that produces tasar silk, but never experimented in Uttarakhand, a Himalayan state of India. A. mylitta express divergent phenotypic characters under different ecological conditions; so, we studied the effect of seven forest tree species in two rearing seasons on variability in silk gland weight of Daba (bivoltine) ecorace of A. mylitta at Forest Research Institute in Dehra Dun, Uttarakhand during 2012 and 2013. We used two-way completely randomized block factorial design and Post HOC Tukey's HSD test to analyse the collected data and there after carried out multiple regression analysis. Results indicated that silk gland weight differed significantly between rearing seasons (DF=1, F=2333.98, p <0.05), host plants (DF 6, F= 1516.25, p <0.05) and their interactions (DF=6, F=7.10, p <0.05). Higher silk gland weight was found in second rearing season than the first on all the host tree species. Terminalia alata fed A. mylitta larvae showed the highest silk gland weight of 8.03 and 9.47 g in first and second rearing seasons, followed by T. tomentosa (7.19 & 9.01g), T. arjuna (6.8 & 8.08 g) and L. speciosa (6.57 & 7.83 g) fed larvae, respectively. Post HOC Tukey's HSD test indicated that silk gland weight of L. speciosa and T. arjuna fed larvae in both the rearing seasons did not differ significantly. E.I. analysis also confirmed that T. alata, T. tomentosa, T. arjuna and L. speciosa are better in their order of merit than T. bellirica , T. chebula and L. tomentosa. Multiple regression analysis indicates that larval weight gain is a strong predictor (β=1.002, t=346.777, p = <0.05) for the silk gland weight of A. mylitta ; however, larval duration had significant negative regression weight (β=-0.270, t=-8.436, p = <0.05) on mean weight of silk gland.

FINITE ELEMENT MODEL TO STUDY TWO DIMENSIONAL UNSTEADY STATE CYTOSOLIC CALCIUM DIFFUSION

Tewari, Shivendra Gajraj,Pardasani, Kamal Raj The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.1

Calcium is a vital second messenger for signal transduction in neurons. Calcium plays an important role in almost every part of the human body but in neuronal cytosol, it is of utmost importance. In order to understand the calcium signaling mechanism in a better way a finite element model has been developed to study the flow of calcium in two dimensions with time. This model assumes EBA (Excess Buffering Approximation), incorporating all the important parameters like time, association rate, influx, buffer concentration, diffusion constant etc. Finite element method is used to obtain calcium concentration in two dimensions and numerical integration is used to compute effect of time over 2-D Calcium profile. Comparative study of calcium signaling in two dimensions with time is done with other important physiological parameters. A MATLAB program has been developed for the entire problem and simulated on an x64 machine to compute the numerical results.

Paper Ionophoretic Technique in the Study of Mixed Complexes

Tewari, Brij Bhushan Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.5

Stability constants of complexes of aluminium(III) and thorium(IV) with methionine and cysteine have been determined by modified paper electrophoretic technique at $\mu$ = 0.1 M. The proportion of ionic species of methionine and cysteine were varied by changing pH of background electrolyte. The stability constants of the complexes metal-methionine-cysteine have been found to be 4.31 ± 0.12 and 5.40 ± 0.19 (log K values) for $Al^{3+}\;and\;Th^{4+} $ complexes, at temperature 35 ${^{\circ}C}$, respectively.

Variable Density Yield Model for Irrigated Plantations of Dalbergia sissoo Grown Under Hot Arid Conditions in India

Tewari, Vindhya Prasad Institute of Forest Science 2012 Journal of Forest Science Vol.28 No.4

Yield tables are a frequently used data base for regional timber resource forecasting. A normal yield table is based on two independent variables, age and site (species constant), and applies to fully stocked (or normal) stands while empirical yield tables are based on average rather than fully stocked stands. Normal and empirical yield tables essentially have many limitations. The limitations of normal and empirical yield tables led to the development of variable density yield tables. Mathematical models for estimating timber yields are usually developed by fitting a suitable equation to observed data. The model is then used to predict yields for conditions resembling those of the original data set. It may be accurate for the specific conditions, but of unproven accuracy or even entirely useless in other circumstances. Thus, these models tend to be specific rather than general and require validation before applying to other areas. Dalbergia sissoo forms a major portion of irrigated plantations in the hot desert of India and is an important timber tree species where stem wood is primarily used as timber. Variable density yield model is not available for this species which is very crucial in long-term planning for managing the plantations on a sustained basis. Thus, the objective of this study was to develop variable density yield model based on the data collected from 30 sample plots of D. sissoo laid out in IGNP area of Rajasthan State (India) and measured annually for 5 years. The best approximating model was selected based on the fit statistics among the models tested in the study. The model develop was evaluated based on quantitative and qualitative statistical criteria which showed that the model is statistically sound in prediction. The model can be safely applied on D. sissooo plantations in the study area or areas having similar conditions.

Development of a Stand Density Management Diagram for Teak Forests in Southern India

Tewari, Vindhya Prasad,Alvarez-Gonz, Juan Gabriel Institute of Forest Science 2014 Journal of Forest Science Vol.30 No.3

Stand Density Diagrams (SDD) are average stand-level models which graphically illustrate the relationship between yield, density and mortality throughout the various stages of forest development. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. This contribution presents an example of a SDD that has been constructed for teak forests of Karnataka in southern India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is represented in one graph. The relative spacing index was used to characterize the population density. Two equations were fitted simultaneously to the data collected from 27 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height while the other relates total stand volume with quadratic mean diameter, stand density and dominant height.

Studies on Interaction of Essential Metal Ions with Bioactive Ligands

Tewari, Brij Bhushan Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.6

Complexation reactions of nitrilotriacetate (NTA) and penicillamine with $Cu^{2+}$ and $Co^{2+}$ have been studied in solution phase using paper electrophoresis technique. The stability constants of the complexes Cu(II)-nitrilotriacetate-penicillamine and Co(II)-nitrilotriacetate-penicillamine have been found to be $6.64{\pm}0.03\;and\;5.86{\pm}0.05$ (logarithm stability constant values), respectively at 35$^{\circ}C$ and ionic strength 0.1 M.

Total Wood Volume Equations for Tectona Grandis Linn F. Stands in Gujarat, India

Tewari, Vindhya Prasad,Singh, Bilas Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.4

Tectona grandis (teak) is one of the most important timber species worldwide and India is one of the major teak growing countries. Though some volume equations were developed for teak in India but the models developed were neither evaluated using robust statistical criteria nor validated. Hence, the objective of this study was to develop statistically tested appropriate volume equation to predict total wood volume (over- and under-bark) for teak trees in Gujarat. A total of 41 trees with age varying from 15 to 33 years and diameter at breast height (dbh) from 7.3 to 30.8 cm were felled for the purpose. Linear and non-linear equations were used to model the relationship of the total wood volume with respect to dbh and total height. The equations tested mostly fitted well to the data. Model evaluation and validation indicated that models should be calibrated with local data for greater accuracy in the prediction.