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Analytic functions with conic domains associated with certain generalized $q$-integral operator
OM P. AHUJA,Asena Cetinkaya,Naveen Kumar Jain 대한수학회 2023 대한수학회논문집 Vol.38 No.4
In this paper, we define a new subclass of $k$-uniformly starlike functions of order $\gamma~ (0\leq\gamma<1)$ by using certain generalized $q$-integral operator. We explore geometric interpretation of the functions in this class by connecting it with conic domains. We also investigate $q$-sufficient coefficient condition, $q$-Fekete-Szeg\"{o} inequalities, $q$-Bieberbach-De Branges type coefficient estimates and radius problem for functions in this class. We conclude this paper by introducing an analogous subclass of $k$-uniformly convex functions of order $\gamma$ by using the generalized $q$-integral operator. We omit the results for this new class because they can be directly translated from the corresponding results of our main class.
Geometric properties of starlikeness involving hyperbolic cosine function
OM P. AHUJA,Asena Cetinkaya,Sushil Kumar 대한수학회 2024 대한수학회논문집 Vol.39 No.2
In this paper, we investigate some geometric properties of starlikeness connected with the hyperbolic cosine functions defined in the open unit disk. In particular, for the class of such starlike hyperbolic cosine functions, we determine the lower bounds of partial sums, Briot-Bouquet differential subordination associated with Bernardi integral operator, and bounds on some third Hankel determinants containing initial coefficients.
O.P. Thakur,Lakshman Pandey,Devendra Kumar,Om Parkash 한양대학교 세라믹연구소 2004 Journal of Ceramic Processing Research Vol.5 No.2
Dielectric properties are strongly dependent on crystallization conditions, which determined the amount of SrTiO3 and secondary crystalline phases and the microstructure of the glass ceramics. Earlier reports confirm that the crystallization of the SrTiO3 phase in borosilicate (without an alkali oxide additive) as well as in aluminosilicate glassy matrix is found to be complex and difficult. Glass ceramics with varying amounts of alkali oxide (K2O) have been prepared in the strontium titanate borosilicate glass system. The glasses were crystallized in the temperature range 1073-1325 K. It is observed that the pure strontium titanate (SrTiO3) phase can be crystallized at higher temperature by choosing an optimum amount of alkali oxide (K2O). Dielectric characteristics of glass ceramic samples were measured with respect to frequency (0.1 kHz to 1 MHz) and temperature (300 to 500 K). The value of the dielectric constant is higher when Sr2B2O5 crystallizes as a primary phase while it decreases significantly when SrTiO3 crystallizes as a major crystalline phase. The temperature coefficient of the dielectric constant (TCε) becomes negative as the SrTiO3 phase crystallized out in the glass ceramics and the value of the dielectric constant increases with a higher crystallization temperature and time which finally decides the amount of the SrTiO3 phase. Attempts have also been made to correlate the observed dielectric behavior with the electrical contribution of various crystalline phases, residual glassy matrix, crystal-glass interface region and electrode contribution using the impedance spectroscopic technique.
Sangita Kumari,Rashi Gusain,Niranjan Kumar,Om P. Khatri 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.42 No.-
Lamellar-structured nanomaterials are gaining large interest for tribological applications owing to theirremarkable mechanical and low shearing properties. Herein, polyethylene glycol (PEG)-mediatedhierarchical microspheres of MoS2 nanosheets are synthesized by a facile and single-step hydrothermalreduction of ammonium molybdate in the presence of thiourea. The PEG functions as a soft templatingmaterial and provides hierarchical microspheres of MoS2 nanosheets. Detailed chemical andmicrostructural features of hierarchical microspheres of MoS2 nanosheets are probed by FTIR[14TD$DIF], XPS,Raman, XRD, TGA, FESEM, and HRTEM analyses. Each nanosheet of MoS2 [15TD$DIF]microspheres is composed oflimited number (10–20) of atomic-thick lamellae[3TD$DIF] as deduced from HRTEM images. The MoS2microspheres, as[4TD$DIF] additive[5TD$DIF] provide significantly improved lubrication properties for steel tribo-pair byreducing the friction ( 21%) and the wear (42%) compared to that of fully formulated 10W40 lubricant. The elemental mapping of worn surfaces revealed the deposition of MoS2 nanosheets on the contactinterfaces. The improved lubrication properties are attributed to collective effect of deposition ofdelaminated MoS2 lamellae on the contact interfaces, low shearing and high mechanical strength ofMoS2 nanosheets.
Nanofluid lubrication and high pressure Raman studies of oxygen functionalized graphene nanosheets
Karuna Kara Mishra,Kalpataru Panda,Niranjan Kumar,Deepika Malpani,T.R. Ravindran,Om P. Khatri 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-
Ultralow friction coefficient in reduced graphene oxide (rGO) nanofluid was observed at high pressure lubrication conditions. High pressure Raman spectroscopic studies of graphene oxide (GO) and rGO in a hydrostatic pressure medium in diamond anvil cell (DAC) showed an increase in G-band linewidth in GO but this value was decreased in rGO at same pressure range due to the defect relaxation in sp2 networks. Moreover, loss of recovery of G band linewidth in decompression cycles was clearly noticed in both the samples but it was significantly higher in GO due to the irreversible sp3 into sp2 planar phase.
Pramod K. Rajak,Vijay K. Singh,Asha L. Singh,Narendra Kumar,Om P. Kumar,Vishvajeet Singh,Aniruddha Kumar,Rai Ankita,Shweta Rai,Amiya S. Naik,Prakash K. Singh 한국지질과학협의회 2020 Geosciences Journal Vol.24 No.4
The present study is an attempt to know the temporal and spatial distribution of geochemical components in the lignite deposit of Kapurdi, Barmer Basin (Rajasthan). Lignite samples have been subjected to proximate, ultimate and elemental analyses, and determination of mineral carbon (MINC%). Besides, various minerals and functional groups have been analyzed through X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR). Selected environmentally sensitive and potential hazardous elements like Cu, Cd, Zn, Ni, Cr, Pb, Mn, Al, Fe and Co are determined using atomic absorption spectrophotometer (AAS). To know the association of minerals with organic matter, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) has also been carried out. The concentration of Co, Ni, Cd, Pb, Na, and K is high when compared with world average and is main concern for the environmental and health hazards. The elements like Fe, Ca, Mg, Zn, and Pb have shown increasing trend from top to bottom of the lignite seam with some fluctuations in the values in few bands whereas others do not follow a definite trend of variation along the seam profile.