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Majhi, Sanjit Manohar,Rai, Prabhakar,Raj, Sudarsan,Chon, Bum-Soo,Park, Kyung-Kuen,Yu, Yeon-Tae American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.10
<P>In this work, Au@Cu<SUB>2</SUB>O core–shell nanoparticles (NPs) were synthesized by simple solution route and applied for CO sensing applications. Au@Cu<SUB>2</SUB>O core–shell NPs were formed by the deposition of 30–60 nm Cu<SUB>2</SUB>O shell layer on Au nanorods (NRs) having 10–15 nm width and 40–60 nm length. The morphology of Au@Cu<SUB>2</SUB>O core–shell NPs was tuned from brick to spherical shape by tuning the pH of the solution. In the absence of Au NRs, cubelike Cu<SUB>2</SUB>O NPs having ∼200 nm diameters were formed. The sensor having Au@Cu<SUB>2</SUB>O core–shell layer exhibited higher CO sensitivity compared to bare Cu<SUB>2</SUB>O NPs layer. Tuning of morphology of Au@Cu<SUB>2</SUB>O core–shell NPs from brick to spherical shape significantly lowered the air resistance. Transition from p- to n-type response was observed for all devices below 150 °C. It was demonstrated that performance of sensor depends not only on the electronic sensitization of Au NRs but also on the morphology of the Au@Cu<SUB>2</SUB>O core–shell NPs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-10/am5008694/production/images/medium/am-2014-008694_0010.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5008694'>ACS Electronic Supporting Info</A></P>
Almost Ricci Soliton and Gradient Almost Ricci Soliton on 3-dimensional f-Kenmotsu Manifolds
Majhi, Pradip Department of Mathematics 2017 Kyungpook mathematical journal Vol.57 No.2
The object of the present paper is to study almost Ricci solitons and gradient almost Ricci solitons in 3-dimensional f-Kenmotsu manifolds.
TMEDA Catalyzed Henry (Nitroaldol) Reaction under Metal and Solvent-free Conditions
Majhi, Anjoy,Kadam, Santosh T.,Kim, Sung-Soo Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.8
The Henry (nitroaldol) reaction proceeds under mild conditions with catalytic amount of tetramethylethylenediamine (TMEDA) to afford $\beta$-nitro alkanol in considerably excellent yield. Structurally diverse aldehydes react with nitromethane in presence of 0.3 equiv of TMEDA under solvent-free condition at rt. The low catalytic loading and mild reaction condition are the key features of the catalytic method.
Majhi, Sanjit Manohar,Rai, Prabhakar,Yu, Yeon-Tae American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.18
<P>We successfully prepared Au@ZnO core-shell nanoparticles (CSNPs) by a facile low-temperature solution route and studied its gas-sensing properties. The obtained Au@ZnO CSNPs were carefully characterized by X-ray diffraction, transmission electron microscopy (TEM), high-resolution TEM, and UV-visible spectroscopy. Mostly spherical-shaped Au@ZnO CSNPs were formed by 10-15 nm Au NPs in the center and by 40-45 nm smooth ZnO shell outside. After the heat-treatment process at 500 degrees C, the crystallinity of ZnO shell was increased without any significant change in morphology of Au@ZnO CSNPs. The gas-sensing test of Au@ZnO CSNPs was examined at 300 degrees C for various gases including H-2 and compared with pure ZnO NPs. The sensor Au@ZnO CSNPs showed the high sensitivity and selectivity to H2 at 300 degrees C. The response values of Au@ZnO CSNPs and pure ZnO NPs sensors to 100 ppm of H-2 at 300 degrees C were 103.9 and 12.7, respectively. The improved response of Au@ZnO CSNPs was related to the electronic sensitization of Au NPs due to Schottky barrier formation. The high selectivity of Au@ZnO CSNPs sensor toward H2 gas might be due to the chemical as well as catalytic effect of Au NPs.</P>
On *-Conformal Ricci Solitons on a Class of Almost Kenmotsu Manifolds
Majhi, Pradip,Dey, Dibakar Department of Mathematics 2021 Kyungpook mathematical journal Vol.61 No.4
The goal of this paper is to characterize a class of almost Kenmotsu manifolds admitting *-conformal Ricci solitons. It is shown that if a (2n + 1)-dimensional (k, µ)'-almost Kenmotsu manifold M admits *-conformal Ricci soliton, then the manifold M is *-Ricci flat and locally isometric to ℍ<sup>n+1</sup>(-4) × ℝ<sup>n</sup>. The result is also verified by an example.
Majhi, Sanjit Manohar,Naik, Gautam Kumar,Lee, Hu-Jun,Song, Ho-Geun,Lee, Cheul-Ro,Lee, In-Hwan,Yu, Yeon-Tae Elsevier 2018 Sensors and actuators. B, Chemical Vol.268 No.-
<P><B>Abstract</B></P> <P>In this work, Au@NiO core-shell nanoparticles (C-S NPs) as a p-type gas sensing material was synthesized by a facile wet-chemical method, and evaluated their gas sensing properties as compared to the pristine NiO NPs gas sensors. Transmission electron microscope (TEM) results exhibited the well-dispersed formation of Au@NiO C-S NPs having the total size of 70–120 nm and NiO shells having 30–50 nm thickness. The C-S morphology as well as the overall particle sizes are unchanged even at 500 °C. The gas sensing result reveals that the response of Au@NiO C-S NPs gas sensor is higher than pristine NiO NPs gas sensor for 100 ppm of ethanol at 200 °C operating temperature. The baseline resistance in the air for Au@NiO C-S NPs sensor is lowered as compared to pristine NiO NPs, which is due to the increased number of holes as charge carriers in Au@NiO C-S NPs. The high response of Au@NiO core-shell NPs as compared to pristine NiO NPs is attributed to electronic and chemical sensitization effects of Au. In Au@NiO C-S structure, the contact between metal (Au) and semiconductor (NiO) formed a Schottky junction since Au metal acted as electron acceptor, a withdrawal of electrons from NiO by Au metal core leaved behind number of holes as charge carriers in Au@NiO C-S NPs. Therefore, the baseline resistance of Au@NiO C-S NPs greatly decreased than pristine NiO NPs, as a result the Au@NiO C-S NPs showed higher response. On the other hand, in chemical sensitization effect, Au NPs catalyzed to dissociate O<SUB>2</SUB> molecules into ionic species. This work will give some clue to the researchers for the further development of p-type based C-S NPs sensors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Au@NiO core-shell nanoparticles (C-S NPs) maintained spherical morphology and showed porous structure after calcined at 500 °C. </LI> <LI> Au@NiO C-S NPs sensor showed higher ethanol response than pure NiO NPs. </LI> <LI> The baseline resistance of Au@NiO C-S NPs was lowered than pure NiO NPs. </LI> <LI> Au@NiO C-S NPs sensor showed good repeatability. </LI> <LI> The role of Au NPs for high response of Au@NiO C-S NPs was investigated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Au@NiO core-shell nanoparticles (C-S NPs) as a p-type gas sensing material was synthesized by a facile wet-chemical method and shows higher gas sensing properties as compared to the pristine NiO NPs gas sensors.</P> <P>[DISPLAY OMISSION]</P>
Sustainable structural lightweight concrete utilizing high-volume fly ash cenosphere
Majhi, Rajib K.,Patel, Sudeep K.,Nayak, Amar N. Techno-Press 2021 Advances in concrete construction Vol.12 No.3
This paper explores the most feasible technique for producing sustainable structural lightweight concrete (LWC) utilizing high-volume of fly ash cenosphere (FAC), a noble lightweight fine material, as replacement of natural fine aggregate (NFA) with addition of silica fume (SF) as replacement of ordinary Portland cement (OPC). Concrete mixes are designed for different combinations of FAC (60%, 80% and 100%), SF (10%, 15% and 20%) and water-binder (W/B) ratio (0.40, 044 and 0.48) and their mechanical and physical properties are evaluated. Experimental results depict that appropriate dose of SF improves the properties of high-volume FAC based concrete and thus helps in the production of structural LWC satisfying strength and density criteria of ACI 213R-14 (2014). The combinations of 15% SF with 80% FAC at 0.44 and 0.40 W/B ratios result in the properties closer to or even better than the normal concrete. Moreover, the environmental impacts of the concrete mixes comprised of high-volume FAC with addition of SF at different W/B ratio reduce in the range 5.37%-18.86% with respect to the normal concrete. Hence, the structural LWC mixes become sustainable, as they are advantageous from both environmental and social considerations.
Almost Kenmotsu Metrics with Quasi Yamabe Soliton
Pradip Majhi,Dibakar Dey 경북대학교 자연과학대학 수학과 2023 Kyungpook mathematical journal Vol.63 No.1
In the present paper, we characterize, for a class of almost Kenmotsu mani folds, those that admit quasi Yamabe solitons. We show that if a (k, µ)′ -almost Kenmotsu manifold admits a quasi Yamabe soliton (g, V, λ, α) where V is pointwise collinear with ξ, then (1) V is a constant multiple of ξ, (2) V is a strict infinitesimal contact transformation, and (3) (£V h′)X = 0 holds for any vector field X. We present an illustrative example to support the result.
Sachchit Majhi,K.K. Pant, 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
Methane conversion to higher hydrocarbons was studied over gallium modified Mo/HZSM-5 catalyst. It was demonstrated that the small amount of methanol addition in the methane stream improves the catalyst activity and selectivity toward aromatics hydrocarbon. The calcined catalysts were characterized using BET surface area, pore volume distribution, TPR, TPD, XRD, FTIR and SEM analysis. A maximum methane conversion (up to 15.5% with 88.7% aromatic selectivity) was achieved over 2%Ga-5%Mo/HZSM-5 catalyst. The catalytic activity over 5%Mo/HZSM-5 and 2%Ga-5%Mo/HZSM-5 catalyst revealed that 2%Ga-5%Mo/HZSM-5 leads to better methane conversion. This was attributed to aromatization property of gallium which facilitated the hydrogen transfer reaction with methane.