On the Decomposition of Cyclic G-Brauer's Centralizer Algebras

Vidhya, Annamalai,Tamilselvi, Annamalai Department of Mathematics 2022 Kyungpook mathematical journal Vol.62 No.1

In this paper, we define the G-Brauer algebras $D^G_f(x)$, where G is a cyclic group, called cyclic G-Brauer algebras, as the linear span of r-signed 1-factors and the generalized m, k signed partial 1-factors is to analyse the multiplication of basis elements in the quotient $^{\rightarrow}_{I_f}^G(x,2k)$. Also, we define certain symmetric matrices $^{\rightarrow}_T_{m,k}^{[\lambda]}(x)$ whose entries are indexed by generalized m, k signed partial 1-factor. We analyse the irreducible representations of $D^G_f(x)$ by determining the quotient $^{\rightarrow}_{I_f}^G(x,2k)$ of $D^G_f(x)$ by its radical. We also find the eigenvalues and eigenspaces of $^{\rightarrow}_T_{m,k}^{[\lambda]}(x)$ for some values of m and k using the representation theory of the generalised symmetric group. The matrices $T_{m,k}^{[\lambda]}(x)$ whose entries are indexed by generalised m, k signed partial 1-factors, which helps in determining the non semisimplicity of these cyclic G-Brauer algebras $D^G_f(x)$, where G = ℤ_r.

Role of Graphene Oxide as a Sacrificial Interlayer for Enhanced Photoelectrochemical Water Oxidation of Hematite Nanorods

Annamalai, Alagappan,Kannan, Aravindaraj G.,Lee, Su Yong,Kim, Dong-Won,Choi, Sun Hee,Jang, Jum Suk American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.34

<P>Photoelectrochemical cells (PECs) with a structure of F-doped SnO<SUB>2</SUB> (FTO)/graphene oxide (GO)/hematite (α-Fe<SUB>2</SUB>O<SUB>3</SUB>) photoanode were fabricated, in which GO serves as a sacrificial underlayer. In contrast to low-temperature sintering carried out under a normal atmosphere, high-temperature sintering was carried out for the GO underlayer-based hematite photoanodes. The photocurrent density of the PECs with GO underlayers gradually increased as the spin speed of the FTO substrate increased. In particular, GO at a spin speed of 5000 rpm showed the highest photocurrent of 1.3 mA/cm<SUP>2</SUP>. The higher performance of the GO/α-Fe<SUB>2</SUB>O<SUB>3</SUB> photoanodes was attributed to the improved FTO/α-Fe<SUB>2</SUB>O<SUB>3</SUB> interface. When sintered at 800 °C for activation of the hematite (FTO/GO/α-Fe<SUB>2</SUB>O<SUB>3</SUB>) photoanodes, the GO layers before being decomposed act as localized hot zones at the FTO/α-Fe<SUB>2</SUB>O<SUB>3</SUB> interface. These localized hot zones play a very crucial role in reducing the microstrain (increased crystallinity) which was confirmed from the synchrotron X-ray diffraction studies. The sacrificial GO underlayer may contribute to relaxing the inhomogeneous internal strain of the α-Fe<SUB>2</SUB>O<SUB>3</SUB> nanorods and reducing the deformation of FTO to an extent. In other words, the reduction of the microstrain minimizes the lattice imperfections and defects at the FTO/α-Fe<SUB>2</SUB>O<SUB>3</SUB> interface, which may enhance the charge collection efficiency, as demonstrated by the impedance measurements. From the EXAFS analysis, it is clearly evident that the sacrificial GO underlayer does not affect the structure of α-Fe<SUB>2</SUB>O<SUB>3</SUB> in the short range. The effects of the GO sacrificial layers are restricted to the FTO/α-Fe<SUB>2</SUB>O<SUB>3</SUB> interface, and they do not affect the bulk properties of α-Fe<SUB>2</SUB>O<SUB>3</SUB>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-34/acs.jpcc.5b06450/production/images/medium/jp-2015-06450j_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b06450'>ACS Electronic Supporting Info</A></P>

Preparation and Characterization of Bioceramic Nanocomposites Based on Hydroxyapatite (HA) and Carboxymethyl Cellulose (CMC)

Annamalai Pratheep Kumar,Kamal Khaja Mohaideen,Sameh A. S. Alariqi,Raj Pal Singh 한국고분자학회 2010 Macromolecular Research Vol.18 No.12

We report the synthesis of biomimetic nanocomposites based on carboxymethyl cellulose (CMC) and hydroxyapatite (HA) nanoparticles via a co-precipitation method. Physico-chemical characterization was performed before and after calcination by Fourier transform infrared (FTIR) spectroscopy, solid state 31P nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). The formation of nanocomposites was observed by wide angle X-ray diffraction (WAXD), scanning electron microscopy (SEM) with energy dispersive Xray analysis (EDX), and transmission electron microscopy (TEM). The spectral and crystallographic data indicated the formation of hydroxyapatite in the presence of CMC. They were observed as aggregates of HA nanoparticles and CMC, whose sizes were approximately ~ 260 ± 40 nm. The crystallite size of the hydroxyapatite particles decreased (with 2 wt% 18 ± 3 nm) with increasing CMC content. The morphological aspects of the calcined samples revealed the sintering ability of HA nanoparticles. Nanocomposites of hydroxyapatite nanoparticles that mimic the process of nucleation and growth in nature can be prepared using biomacromolecules such as CMC.

Fabrication of superior α-Fe₂O₃ nanorod photoanodes through ex-situ Sn-doping for solar water splitting

Annamalai, Alagappan,Shinde, Pravin S.,Jeon, Tae Hwa,Lee, Hyun Hwi,Kim, Hyun Gyu,Choi, Wonyong,Jang, Jum Suk Elsevier 2016 Solar energy materials and solar cells Vol.144 No.-

<P><B>Abstract</B></P> <P>Doping transition metals into 1-D nanostructures is of crucial importance for their application in photovoltaics and photoelectrochemical (PEC) systems; performance enhancements arise from both dopant incorporation and the 1-D nanostructures. Both in-situ and ex-situ doping methods have been demonstrated for 1-D hematite (α-Fe<SUB>2</SUB>O<SUB>3</SUB>) nanostructures, with tin (Sn) as the dopant, for photoelectrochemical water oxidation. In-situ Sn-doped hematite photoanodes adopted a morphology consisting of nanocorals with the (104) plane as the preferred direction of crystal growth. As an alternative solution, ex-situ doping not only preserves the vertically-aligned nanorod morphology but also sustains the preferred orientation of the (110) axis, which is favorable for high conductivity in pristine hematite photoanodes. In-situ Sn-doping was carried out by the same method: Sn precursors were added and dissolved in ethanol during the hydrothermal synthesis. Ex-situ doping was carried out in two stages (during pre-deposition and during high temperature sintering). During pre-deposition, a defined amount of the Sn precursor was introduced near the surface region of the 1-D nanostructure, and the Sn content was controlled by changing the concentration of the precursor solution. In subsequent high temperature sintering (800°C), the dopant atoms diffused into the hematite lattice to attain the desired doping profile. We found that ex-situ Sn-doping resulted in a 60% increase in the photocurrent while in-situ Sn-doping yielded an increase of only 20% in the photocurrent, as compared with pristine hematite photoanodes, at 1.4 V <I>vs.</I> RHE. The improvement in the photocurrent was caused by a combination of Sn dopants in the hematite, which act as electron donors by increasing the donor density, and better surface charge transfer kinetics, thereby enhancing the overall device performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In-situ and ex-situ doping methods were compared for α-Fe<SUB>2</SUB>O<SUB>3</SUB> with Sn as a dopant. </LI> <LI> Ex-situ Sn-doping has 60% higher photocurrent compared to pristine photoanodes. </LI> <LI> Ex-Situ retains highly conductive (110) crystal plane and nanorod morphology. </LI> <LI> In-situ has lot of grain boundaries (nano-corals) and less conductive (104) phase. </LI> <LI> All doping problems related to β-FeOOH phase has been avoided in ex-situ doping. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Activation of Hematite Photoanodes for Solar Water Splitting: Effect of FTO Deformation

Annamalai, Alagappan,Subramanian, Arunprabaharan,Kang, Unseock,Park, Hyunwoong,Choi, Sun Hee,Jang, Jum Suk American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.7

<P>The sintering at 800 °C is found to induce the diffusion of Sn from the F-doped SnO<SUB>2</SUB> (FTO) into the hematite lattice, enhancing the photoelectrochemical cell (PEC) properties of the hematite photoanodes, but this diffusion also has detrimental effects on the conductivity of the FTO substrate. In the present research we examined the role of FTO deformation during the activation of hematite photoanodes synthesized on FTO substrates. The incorporation of Sn dopants from the FTO substrates in the hematite lattice was confirmed by X-ray photoelectron spectroscopy and was found to increase with sintering time. Further from the extended X-ray absorption fine structure analysis, it was found that the diffused Sn atoms affected the metal sites of the hematite lattice. Increased diffusion of Sn into the hematite lattice caused structural disordering of the FTO, but optimum sintering time compensated for the structural disordering and improved the ordering. Under high-temperature annealing at 800 °C, the FTO substrates underwent a stoichiometric change that directly affected their electrical conductivity; their resistivity was doubled after 20 min of sintering. Activation of hematite photoanodes by high-temperature sintering entails a kinetic competition between Sn dopant diffusion from the FTO substrate into the hematite and the resulting thermal deformation and conductivity loss in the FTO substrates.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-7/jp512189c/production/images/medium/jp-2014-12189c_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp512189c'>ACS Electronic Supporting Info</A></P>

Surface energy and wettability of van der Waals structures

Annamalai, M.,Gopinadhan, K.,Han, S.,Saha, S.,Park, H.,Cho, E.,Kumar, B.,Patra, A.,Kim, S. W.,Venkatesan, T. Royal Society of Chemistry 2016 Nanoscale Vol.8 No.10

<P>The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of hexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London-vdW force-mediated wettability.</P>

Application of Zn2SnO4 Nanoparticles in Dye Sensitized Solar Cells

( Alagappan Annamalai ),장점석,이만종 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.0

Transportation Problem for Interval Valued Trapezoidal Intuitionistic Fuzzy Numbers

Manivannan Annamalai,J. Jansi Rani,S. Dhanasekar 한국지능시스템학회 2022 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.22 No.2

The aim of the decision-makers in the transportation industry is to maximize profit by minimizing the transportation cost. The transportation structure is the center of economic activity inthe business logistics system. However, transportation costs may vary owing to various unpredictable factors. In this study, cost of the transporting unit is considered as an interval valuedtrapezoidal intuitionistic fuzzy number to deal with these uncertainties. The transportationproblem with interval-valued trapezoidal intuitionistic fuzzy cost is discussed here, and thecosts are ordered by score and score expected functions. As a special case, the interval-valuedtrapezoidal intuitionistic cost is not converted into crisp numbers to solve the transportationproblem and derive the initial basic feasible (IBF) solution through interval-valued intuitionistic costs. Furthermore, the optimality of the derived initial basic feasible solution is checkedusing the modified distribution (MODI) method. The effectiveness and validation of thedeveloped approach were illustrated using numerical examples.

Investigations on aluminium hybrid composites reinforced with ZrB2/Al2O3/Multi-Walled Carbon Nanotube (MWCNT) for aerospace applications

Elaya Perumal Annamalai,Jinu GR,Vidhyalakshmi S,Amal Bosco Jude S 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.5

The Aluminium Alloy (AA7050) hybrid composites (AAHC’s) reinforced with 2-10 wt.% ZrB2 ceramic particles, 1-5 wt.%Al2O3 particles and 0.5-2.5 wt.% MWCNT in novel Vibro-compo casting through liquid casting route. The ZrB2 and Al2O3have been introduced in the conventional method, and MWCNT is injected by argon gas. Then, the stirring process wascarried out in different temperatures to enhance wettability between reinforcements and matrix. The developed AAHC’s werecharacterised using a Scanning Electron Microscope (SEM) and Energy-dispersive X-ray spectroscopy analysis (EDS). Themechanical properties like hardness, tensile, impact and fatigue tests were performed on all the casted samples elaborately. The dispersion of ZrB2 ceramic particles and its implanting over the ductile Al7050 matrix was effectively obtained, whichshown superior mechanical properties when compared to monolithic Al7050 alloy. The specimen contained 1.5%MWCNT +6%ZrB2 + 3%Al2O3 reveals the greater tensile strength, which is 30.73% higher than the base material. Besides, the EDSresults ensured the manufacturing of Al 7050/MWCNT + ZrB2+Al2O3 metal matrix composites successfully, and no otherintermetallic phases were identified.

A Cross-Layer Unequal Error Protection Scheme for Prioritized H.264 Video using RCPC Codes and Hierarchical QAM

Wei Ho Chung,Sunil Kumar,Seethal Paluri,Santosh Nagaraj,Annamalai Annamalai Jr,D Matyjas John 한국정보처리학회 2013 Journal of information processing systems Vol.9 No.1