Computational and Experimental Study on Electronic Band Structure of Bismuth Ferrite: A Promising Visible Light Photocatalyst

G Thamizharasan,Eithiraj R,D,Enhbayar Enhtuwshin,So Jung Kim,Niroj Kumar Sahu,Arpan Kumar Nayak,HyukSu Han 한국세라믹학회 2020 세라미스트 Vol.23 No.4

Electronic band structure of bismuth ferrite (BFO) is studied by computational and experimental methods. Bandgap of BFO is precisely determined using optical absorption spectra as well as density functional calculation (DFT). Both methods give a comparable result that BFO can have both of direct or indirect (very close to direct) bandgap of about 2.0~2.2 eV. Furthermore, electronic transition in BFO occurs via the unoccupied O 2p to the occupied Fe 3d states or the d-d transition in Fe 3d states. Intriguing electronic structure of BFO, a narrow bandgap and a multiple electronic transition route, render it as a promising candidate for a visible light photocatalyst.

PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

Zheng, W.,Shen, R. F.,Sakamoto, T.,Beardmore, A. P.,De Pasquale, M.,Wu, X. F.,Gorosabel, J.,Urata, Y.,Sugita, S.,Zhang, B.,Pozanenko, A.,Nissinen, M.,Sahu, D. K.,Im, M.,Ukwatta, T. N.,Andreev, M.,Klun IOP Publishing 2012 The Astrophysical journal Vol.751 No.2

<P>We present a comprehensive analysis of a bright, long-duration (T-90 similar to 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the gamma-ray band, with optical light curve showing correlation with gamma-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to gamma-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission (similar to 1100 s), a bright (R = 14.0) optical emission hump with very steep rise (alpha similar to 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R-GRB similar to 3 x 10(13) cm), initial Lorentz factor of the outflow (Gamma(0) similar to 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.</P>

Nutrient Utilisation and Rumen Fermentation Pattern in Murrah Buffaloes (Bubalus bubalis) Fed Urea and Urea Plus Hydrochloric Acid Treated Wheat Straw

Dass, R.S.,Verma, A.K.,Mehra, U.R.,Sahu, D.S. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.11

Wheat straw was treated on laboratory scale with 4% urea at a moisture level of 50% along with different amount of HC1 to fix various levels of ammonia (30, 40, 50 and 60%) and stored for 4 weeks. Result, revealed a significant (p<0.01) increase in CP content of the samples where HC1 was added. The CP content of the straw was only 7.8%, which increased to 14.1, 16.0, 15.0 and 15.2% with the addition of acid. Similarly the concentrations of NDF, ADF and hemicellulose was significantly different due to HC1 addition. The level of HC1 recommended was to trap 30% ammonia as there was not significant difference in CP content of straw due to addition of 4 levels of acids. Results of in vivo experiment conducted on nine buffaloes divided randomly into three groups of three animals in each revealed no significant difference in the intake of DM, OM, NDF, ADF, cellulose and hemicellulose in group I (ammoniated straw), group II (HC1 treated ammoniated straw) and group III (HC1 treated ammoniated straw + 1 kg barley grain), but the intake of CP was significantly (p<0.01) more in group III as compared to other 2 groups. The digestibility of DM, OM and CP was significantly (p<0.01) more in groups where HCI treated straw was fed as compared to only ammoniated straw fed group, whereas there was no significant difference in the digestibility of NDF, ADF and cellulose in 3 groups. Intake was significantly higher of nitrogen (p<0.05), calcium (p<0.01) and phosphorus (p<0.01) in group III as compared to other two groups. Animals in all the 3 groups showed positive nitrogen, calcium and phosphorus balance, though the balances of all the 3 nutrients were significantly higher in group III as compared to other 2 groups. Rumen fermentation study conducted in 3 rumen fistulated buffaloes in $3{\times}3$ latin square design offering the same 3 diets as in group I to III revealed that rumen pH was alike statistically in 3 groups and at various time intervals. The mean ammonia-N concentration was significantly (p<0.01) more in group II and III as compared to group I. The mean TVFA concentration (mM/100 ml SRL) were 6.46, 7.84 and 8.47 in 3 groups respectively and different statistically (p<0.01). Results revealed no significant difference in the activities of carboxy methyl cellulase, urease or protease at both the time of sampling (0 h and 4 h) in all the 3 groups of animals.

High UV absorption efficiency of nanocrystalline ZnO synthesized by ultrasound assisted wet chemical method

N.R. Panda,D. Sahu,B.S. Acharya,P. Nayak 한국물리학회 2015 Current Applied Physics Vol.15 No.3

Ultrasound assisted wet-chemical method has been carried out to incorporate different metal and nonmetal ions such as; Li, S and Ag into ZnO. Characteristic studies on the structural and optical properties of the samples especially; the ultra-violet (UV) light absorption have been carried out. X-ray diffraction (XRD) analysis shows the formation of hexagonal crystal structure of ZnO along with changes in crystallinity and micro-strain with impurity doping. The morphology of the doped samples changes from particle like structure to flower and rod like structures showing the influence of dopant ions on nano ZnO growth. Infra-red (IR) transmittance spectra give information about the presence of metaleoxygen bond along with other stretching and bending modes. UVevisible absorption studies show the narrowing and sharpening of UV absorption band along with a blue shift for the doped samples. This shows the intensification in the excitonic absorption in ZnO after doping specific elements which will find application in UV blocking agents. Photoluminescence (PL) measurement shows the presence of excitonic emission and emissions due to intrinsic defects and external impurities in UV and visible regions respectively. These emission bands show a change in their position and intensity which has been explained on the basis of the existence of impurity levels in the band gap of ZnO.

Effect of Feeding Urea and Acetic Acid Treated Wheat Straw on the Digestibility of Nutrients in Adult Male Murrah Buffaloes (Bubalus bubalis)

Mehra, Usha R.,Dass, R.S.,Verma, A.K.,Sahu, D.S. Asian Australasian Association of Animal Productio 2001 Animal Bioscience Vol.14 No.12

Wheat straw was treated on laboratory scale with 4% urea at a moisture level of 50% along with different amounts of acetic acid (AA) to fix various levels of ammonia nitrogen (15, 30, 45 and 60%) evolved from urea and stored for 4 weeks. Chemical composition of the treated samples revealed a significant (p<0.01) increase in N content of the samples where AA was added. The N content of the ammoniated straw was only 1.21% which increased to 2.58 with the addition of AA to trap 30% $NH_3-N$. The concentration of free $NH_3-N$ in the straw was significantly (p<0.01) less when more than 15% $NH_3-N$ was trapped with AA. There was significant increase (p<0.01) in N disappearance and depression in NDF and hemicellulose disappearance, when AA was used to trap 30% $NH_3-N$. Large scale treatment of wheat straw with 4% urea at a moisture level of 50% along with AA (to trap 30% $NH_3-N$) increased the N content, but not as much as in laboratory scale treatment. In vivo experiment conducted on nine adult male buffaloes divided into three groups revealed no difference in the intake of DM, OM, NDF, ADF, cellulose and hemicellulose among group I (ammoniated straw), group II (AA treated ammoniated straw) and group III (AA treated ammoniated straw +1 kg barley grain), but the intake was significantly (p<0.05) more in groups where AA treated straw was fed as compared to only ammoniated straw fed group. However EE digestibility was depressed in group II. The digestibility of cellulose and hemicellulose both depressed significantly (p<0.05) in group II and III as compared to group I. Animals in all the 3 groups showed positive nitrogen balance and it was significantly more in group II and III as compared to group I. DCP intake was significantly (p<0.05) more in group II and III as compared to group I, but there was no significant difference among the three groups in TDN intake. It can be concluded that AA (to trap 30% $NH_3-N$) is effective in capturing the excess ammonia released during urea ammoniation of straw and improving its nutritive value, as well as animal performance.

Common fixed point theorems for two pairs of non-self mappings

M. Imdad,Ladlay Khan,D. R. Sahu 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.21 No.1-2

Complex Chiral Colloids and Surfaces via High-Index Off-Cut Silicon

McPeak, Kevin M.,van Engers, Christian D.,Blome, Mark,Park, Jong Hyuk,Burger, Sven,Gosá,lvez, Miguel A.,Faridi, Ava,Ries, Yasmina R.,Sahu, Ayaskanta,Norris, David J. American Chemical Society 2014 NANO LETTERS Vol.14 No.5

<P>Silicon wafers are commonly etched in potassium hydroxide solutions to form highly symmetric surface structures. These arise when slow-etching {111} atomic planes are exposed on standard low-index surfaces. However, the ability of nonstandard high-index wafers to provide more complex structures by tilting the {111} planes has not been fully appreciated. We demonstrate the power of this approach by creating chiral surface structures and nanoparticles of a specific handedness from gold. When the nanoparticles are dispersed in liquids, gold colloids exhibiting record molar circular dichroism (>5 × 10<SUP>9</SUP> M<SUP>–1</SUP> cm<SUP>–1</SUP>) at red wavelengths are obtained. The nanoparticles also present chiral pockets for binding.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-5/nl501032j/production/images/medium/nl-2014-01032j_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl501032j'>ACS Electronic Supporting Info</A></P>

An experimental and simulation study of novel channel designs for open-cathode high-temperature polymer electrolyte membrane fuel cells

Thomas, S.,Bates, A.,Park, S.,Sahu, A.K.,Lee, S.C.,Son, B.R.,Kim, J.G.,Lee, D.H. Applied Science Publishers 2016 APPLIED ENERGY Vol.165 No.-

<P>A minimum balance of plant (BOP) is desired for an open-cathode high temperature polymer electrolyte membrane (HTPEM) fuel cell to ensure low parasitic losses and a compact design. The advantage of an open-cathode system is the elimination of the coolant plate and incorporation of a blower for oxidant and coolant supply, which reduces the overall size of the stack, power losses, and results in a lower system volume. In the present study, we present unique designs for an open-cathode system which offers uniform temperature distribution with a minimum temperature gradient and a uniform flow distribution through each cell. Design studies were carried out to increase power density. An experimental and simulation approach was carried out to design the novel open-cathode system. Two unique parallel serpentine flow designs were developed to yield a low pressure drop and uniform flow distribution, one without pins and another with pins. A five-cell stack was fabricated in the lab based on the new design. Performance and flow distribution studies revealed better performance, uniform flow distribution, and a reduced temperature gradient across the stack; improving overall system efficiency. (C) 2015 Elsevier Ltd. All rights reserved.</P>

Assaying of SNM using Simultaneous Detection of Fission Neutrons and Gammas by Employing a Novel Phoswich Detector

Sonu,Mohit Tyagi,A. Kelkar,A. Sahu,M. Sonawane,P.S. Sarkar,A. Pandey,D.B. Sathe,G.D. Patra,T. Vincent,S.G. Singh,R.B. Bhatt Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.7

For the precise measurements of special nuclear materials (SNM) including Pu and Am isotopes, we have used phoswich detector combination of two single crystal scintillators of Gd₃Ga₃Al₂O₁₂:Ce and CsI:Tl. High detection efficiency and sensitivity along with high figure of merit for the discrimination of these phoswich detectors ensures the detection and discrimination of thermal neutrons and gammas from spontaneous fission of Pu and other isotopes in presence of high gamma background. Using this detector, the low energy gammas, which is stopped completely in 1mm thick disc of GGAG, can be also discriminated from high energies gamma and shows linearity in wide range of sample quantities. By changing only the appropriate shielding, the similar setup was used for thermal neutron detection and shows a very good linearity over wide range. The quantity of a test sample was also calculated accurately by using the measured calibrated plot.