THE <i>SPITZER</i> INFRARED SPECTROGRAPH SURVEY OF PROTOPLANETARY DISKS IN ORION A. I. DISK PROPERTIES

Kim, K. H.,Watson, Dan M.,Manoj, P.,Forrest, W. J.,Furlan, Elise,Najita, Joan,Sargent, Benjamin,Herná,ndez, Jesú,s,Calvet, Nuria,Adame, Lucí,a,Espaillat, Catherine,Megeath, S. T.,Muz American Astronomical Society 2016 The Astrophysical journal Supplement series Vol.226 No.1

<P>We present our investigation of 319 Class II objects in Orion A observed by Spitzer/IRS. We also present the follow-up observations of 120 of these Class II objects in Orion A from the Infrared Telescope Facility/SpeX. We measure continuum spectral indices, equivalent widths, and integrated fluxes that pertain to disk structure and dust composition from IRS spectra of Class II objects in Orion A. We estimate mass accretion rates using hydrogen recombination lines in the SpeX spectra of our targets. Utilizing these properties, we compare the distributions of the disk and dust properties of Orion A disks with those of Taurus disks with respect to position within Orion A (Orion Nebular Cluster [ONC] and L1641) and with the subgroups by the inferred radial structures, such as transitional disks (TDs) versus radially continuous full disks (FDs). Our main findings are as follows. (1) Inner disks evolve faster than the outer disks. (2) The mass accretion rates of TDs and those of radially continuous FDs are statistically significantly displaced from each other. The median mass accretion rate of radially continuous disks in the ONC and L1641 is not very different from that in Taurus. (3) Less grain processing has occurred in the disks in the ONC compared to those in Taurus, based on analysis of the shape index of the 10 mu m silicate feature (F-11.3/F-9.8). (4) The 20-31 mu m continuum spectral index tracks the projected distance from the most luminous Trapezium star, theta(1) Ori C. A possible explanation is UV ablation of the outer parts of disks.</P>

Effect of thickness variation of hole injection and hole blocking layers on the performance of fluorescent green organic light emitting diodes

K. Narayan,S. Varadharajaperumal,G. Mohan Rao,M. Manoj Varma,T. Srinivas 한국물리학회 2013 Current Applied Physics Vol.13 No.1

In this paper we present the effect of thickness variation of hole injection and hole blocking layers on the performance of fluorescent green organic light emitting diodes (OLEDs). A number of OLED devices have been fabricated with combinations of hole injecting and hole blocking layers of varying thicknesses. Even though hole blocking and hole injection layers have opposite functions, yet there is a particular combination of their thicknesses when they function in conjunction and luminous efficiency and power efficiency are maximized. The optimum thickness of CuPc (Copper(II) phthalocyanine) layer, used as hole injection layer and BCP (2,9 dimethyl-4,7-diphenyl-1,10-phenanthroline) used as hole blocking layer were found to be 18 nm and 10 nm respectively. It is with this delicate adjustment of thicknesses, charge balancing is achieved and luminous efficiency and power efficiency were optimized. The maximum luminous efficiency of 3.82 cd/A at a current density of 24.45 mA/cm2 and maximum power efficiency of 2.61 lm/W at a current density of 5.3 mA/cm2 were achieved. We obtained luminance of 5993 cd/m2 when current density was 140 mA/cm2. The EL spectra was obtained for the LEDs and found that it has a peaking at 524 nm of wavelength.

Polarized Raman scattering and lattice eigenmodes of antiferromagnetic NdFeO₃

Singh, Manoj K.,Jang, Hyun M.,Gupta, H. C.,Katiyar, Ram S. John Wiley Sons, Ltd. 2008 JOURNAL OF RAMAN SPECTROSCOPY - Vol.39 No.7

<P>The first- and second-order Raman-active phonons in the orthorhombic Pbnm NdFeO<SUB>3</SUB> single crystals were studied by means of polarized Raman scattering and lattice dynamics computations (LDC). The zone-center phonons of A<SUB>g</SUB> symmetry were distinguished from the B<SUB>1g</SUB> eigenmodes by performing polarized Raman scattering experiments using two parallel polarization configurations, X′(ZZ)X′ and Z(X′X′)Z. With the help of LDC, we were able to assign most of the observed Raman-active modes, including phonons of B<SUB>2g</SUB> and B<SUB>3g</SUB> symmetry. The LDC results indicated that among the 16 force constants employed, the one corresponding to the stretching vibration between the central Fe cation and the axial oxygen atom in a FeO<SUB>6</SUB> octahedron unit had the largest value. This suggests that the B-site Fe cation is more tightly bound to the axial O1 ion than the other two equatorial O2 ions. It was further shown that at higher wavenumbers, the displacement of oxygen atoms contributed dominantly to the zone-center vibrations. Copyright © 2008 John Wiley & Sons, Ltd.</P>

Anti-Cell Proliferative Efficacy of Ferulic Acid Against 7, 12-dimethylbenz(a) Anthracene Induced Hamster Buccal Pouch Carcinogenesis

Prabhakar, M. Manoj,Vasudevan, K.,Karthikeyan, S.,Baskaran, N.,Silvan, S.,Manoharan, S. Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

The present study was designed to explore the anti-cell proliferative efficacy of ferulic acid by analysing the expression pattern of cell proliferative markers, proliferating cellular nuclear antigen (PCNA) and cyclin D1, in the buccal mucosa of golden Syrian hamsters treated with 7,12-dimethylbenz(a)anthracene (DMBA). Oral squamous cell carcinomas developed in the buccal pouch of hamsters using topical application of 0.5% DMBA three times a week for 14 weeks. Immunohistochemical (PCNA) and RT-PCR (Cyclin D1) analysis revealed over expression of PCNA and cyclin D1 in the buccal mucosa of hamsters treated with DMBA alone (tumor bearing hamsters). Oral administration of ferulic acid at a dose of 40 mg/kg bw to hamsters treated with DMBA not only completely prevented the tumor formation but also down regulated the expression of PCNA and cyclin D1. The results of the present study thus suggests that ferulic acid might have inhibited tumor formation in the buccal mucosa of hamsters treated with DMBA through its anti-cell proliferative potential as evidenced by decreased expression of PCNA and cyclin D1.

Polarized Raman scattering of multiferroicBiFeO3thin films with pseudo-tetragonal symmetry

Singh, Manoj K.,Ryu, Sangwoo,Jang, Hyun M. American Physical Society 2005 Physical review. B, Condensed matter and materials Vol.72 No.13

Influence of B4C on Dry Sliding Wear Behavior of B4C/Al–Mg–Si Composites Synthesized via Powder Metallurgy Route

Neeraj Kumar,M. K. Manoj 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

The aim of this work is to fabricate aluminum, boron carbide (B4C) based aluminum matrix composites (AMCs) using easyand cost effective powder metallurgy (P/M) route. Here, Al–Mg–Si composites having different weight fractions of B4C(3.5,7.0,10.5,14.0 and 17.5 wt%) were synthesized to study the dry sliding wear behavior with respect to automobile brakepad material. The surface morphology and elemental composition of fabricated composite material were characterized byScanning Electron Microscope (SEM) and energy dispersive x-ray spectroscopy (EDS) respectively. Further, dry sliding weartests were conducted with respect to i.e. applied loads, sliding distances and reinforcements for the performance analysis ofsynthesized AMCs. A linear regression model was used to optimize the control factors. Furthermore, explore the effects ofreinforcements on density, Vickers hardness, wear rate and worn out surface morphology. Further, the analysis also revealedthe critical wear mechanisms with their wear debris for improvement in the AMCs. The hardness of aluminum composite(17.5% B4C/Al–Mg–Si) showed 54.15% higher value than matrix alloy. Furthermore, it was observed that AMCs showedsignificant improvement on the various factors e.g., applied load (L), sliding distances (SD) and reinforcements (R) thanthat of aluminium matrix alloy.

Violet luminescence from ZnO nanorods grown by room temperature pulsed laser deposition

R.S. Ajimsha,R. Manoj,P.M. Aneesh,M.K. Jayaraj 한국물리학회 2010 Current Applied Physics Vol.10 No.2

ZnO thin films were deposited at room temperature by pulsed laser deposition (PLD) varying the oxygen pressure. Morphological analysis using scanning electron microscope (SEM) and atomic force microscopy (AFM) demonstrated the formation of ZnO nanorods at a particular oxygen pressure. Room temperature violet luminescence was observed from these ZnO nanorods and temperature dependence of luminescence was studied. Influence of oxygen pressure on the growth of ZnO thin films by PLD was studied using the X-ray photoelectron spectroscopy of both post ablated targets and deposited films. The ZnO films were crystalline and the formation of crystalline phase is found to follow a pressure–temperature (P–T) scaling with increase of temperature.

Influence of Inhibitors on the Corrosion of Al and Al-composites in Chloride-containing Solutions - A Review

Neeraj Kumar,Ashok K. Srivastava,Prabhat Gautam,M. K. Manoj 한국재료학회 2022 한국재료학회지 Vol.32 No.5

Corrosion is a natural, inevitable process, and is one of the world's most serious problems. Losses incurred due to corrosion are extremely expensive for society. Several technological strategies have been explored and implemented to address these losses. The use of inhibitors to prevent corrosion is a common and efficient method to reduce corrosion losses. This review covers Al and Al-composite corrosion inhibitors in chloride-containing solutions, because of their popularity in a broad array of industrial applications. A vast number of studies in the literature detail the common tendency of Al and Al-composites with reinforcements to deteriorate. Accordingly, it is worthwhile to employ inhibitors to protect them, as discussed in the present work. The emphasis is on selecting the smartest corrosion inhibitor and evaluating its performance. According to the study, the most commonly used corrosion inhibitors are 1,4-naphthoquinone (NQ), 1,5-naphthalene diol, 3-amino-1,2,4-triazole-5-thiol (ATAT), ammonium tetrathiotungstate, clotrimazole, amoxicillin, antimicrobial and antifungal drugs. Electrochemical impedance spectroscopy (EIS), potentiodynamic (PDP), and weight loss were among the most commonly used modern electrochemical technologies to test inhibitors’ efficacy under environmental conditions.

Material Flow Behavior and Mechanical Properties of Dissimilar Friction Stir Welded Al 7075 and Mg AZ31 Alloys Using Cd Interlayer

Satya Kumar Dewangan,M. K. Tripathi,M. K. Manoj 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.5

Friction Stir Welding (FSW) has great potential over fusion welding for joining dissimilar alloys. However, formation ofintermetallic compounds (IMCs) Al12Mg17and Al3Mg2in FSW of Al/Mg alloys is almost unavoidable and problematic forthe research community. Such IMCs in the form of continuous layer provide easy crack propagation path which increasesbrittleness and reduces the joint strength of the weld. To improve the material flow behavior and reducing brittleness, accurateand precise attempts were taken to join two dissimilar alloys i.e. Al 7075 and Mg AZ31 with the incorporation of cadmiuminterlayer first time. Tool rotational speed of 1300 rpm and traverse speed of 20 mm/min were maintained throughout thewelding process. Various phase formation and their distribution in the nugget zone has been studied in details by using opticalmicroscopy, SEM–EDS and XRD. The supersaturated solid solution (SSSS) of Mg in Al, and a thin layer of Al3Mg2andsmall particles (~ 1 μm) of Al12Mg17have been observed in the stir zone. During processing Cd reacted with Mg and formedCdMg and CdMg3which have been distributed in the upper-middle portion of Mg region as intercalated lamellar structure. Formation of these compound provided micro-mechanical interlocking. Further, Al material has been found to be depositedinto the Mg region in the form of elongated balloon which provided anchoring effect due to mechanical interlocking. Themaximum tensile strength achieved is 129 MPa which is higher than the previously reported dissimilar FSW of Al 7xxxseries alloy with Mg alloy. Fractographic study of the dissimilar FSW tensile sample was carried out to understand crackpropagation path and scope for further improvement in the weld joint strength.

Perturbations and Regime Shift in an Aquatic Ecosystem along with Adaptation of Biota Due to Climatic Extremes

Satya Panigrahi,Ajit K. Mohanty,Thanapandi Ramesh,K. Jahir Hussain,Manoj K. Samantara,M. V. R. Prasad,Kamala Kanta Satpathy 대한환경공학회 2012 Environmental Engineering Research Vol.17 No.-

The present study aims to observe the post tsunami changes occurring in a small lake. Physicochemical and biological characteristics of Kokilamedu lake (KKM) revealed drastic changes when compared to the pre-tsunami conditions. The monthly average water quality indicated that salinity was increased sharply (11.31 practical salinity unit [psu] in June 2008) from a lowest pre-tsunami value of 1.19 psu (range, 1.19 to 3.41 psu). Similarly, the NO3+NO2 values were increased significantly (0.49 μmol/L in 1996 to 74.47 μmol/L in 2006). The concentration of SiO4 increased remarkably from an average of 64.87 μmol/L during pre-tsunami conditions to 309.71 μmol/L during post-tsunami conditions (2009–2010). Inorganic phosphate was also increased to a maximum of 9.59 μmol/L from a pre-tsunami maximum of 1.09 μmol/L. Chlorophyll-a values did not respond to the increased nutrient stoichiometry and declined during posttsunami conditions. However, there was a significant improvement in oxygen concentration (2006–2010 average, 8.27 mg/L) of the lake compared to the 1996 values (1994–1995 average, 5.94 mg/L). The algal component is now dominated by the blue-green algae which prevailed over the green algae in the pre-tsunami conditions. Certain marine fishes adapted to this altered ecosystem due to a probable regime shift. Remarkably, out of 20 species, five were marine, nine were brackish, and the remaining six were freshwater species. Preand post-tsunami observations from a control site did not exhibit a remarkable shift during 1994–1996 and 2010, whereas a shift was apparent in the case of KKM.