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61.
Pooja Sahlot Gaurav Sharma Vasant Sathe Anil K. Sinha Anand M. Awasthi 《Journal of the American Ceramic Society》2020,103(5):3238-3248
From low-temperature Synchrotron X-ray diffraction, a precise thermal characterization of octahedral distortions in single-phase Ruddlesden-Popper Ca3Mn2O7 is performed. Highly sensitive close-steps temperature dependences of Mn-O-Mn bond angles connecting MnO6 octahedra clearly reveal the signature of spin ordering in the system. Spin-lattice coupling is thus revealed via the structural distortions, responsible for the evolution of the magnetic state. Further, benchmark temperature anomalies observed in the unit cell volume and its polarization-measure highlight the interplay between spin, lattice, and charge degrees of freedom. Strong spin-lattice coupling is supported by the Raman spectroscopy results across the magnetic ordering. Dielectric study on Ca3Mn2O7 features relaxor-like segmented dynamics below the antiferromagnetic ordering. Dipolar relaxations of different origins are spectrally resolved, exhibiting distinct H-field alterations which identify their allegiance to different magnetic subphases. Dipole-relaxation characteristics examined under applied magnetic field and the ensuing magneto-dielectricity consistently correlate with the concurrent magnetic, structural, and vibrational features. 相似文献
62.
The stability of the liquid/vapor interface between two concentric revolving cylinders is examined. The transfer of heat/mass is allowed at the interface. Both the cylinders rotate with different angular velocities. The fluids inside the annular region are taken as incompressible and viscous. The theory of viscous potential flow analysis is used to add the viscous effects. The normal mode technique is used to calculate the growth of perturbations. If we rotate the inner cylinder, it is seen that asymmetric disturbances have a destabilizing character at the interface but the rotation of the outer cylinder has a stabilizing effect. We found that an asymmetric disturbance destabilizes the interface if the inner cylinder rotates. It is found that the arrangement gets destabilized on rotating of the inner cylinder but rotation of the outer cylinder induces stability, and the most stable case is found when the inner cylinder is stationary and the outer cylinder is rotating. 相似文献
63.
In this paper, a ray-tracing model is developed using MATLAB based on mathematical formulations used in the design of Fresnel lens with spherical facets. Further, a design chart for Fresnel lens with spherical facets is developed to determine aperture radius and design angle for a given focal length and focus size. Concentration ratio and spherical aberration for Fresnel lens with spherical facets are also compared with those of plano-convex lens and conventional Fresnel lens with triangular facets. Furthermore, the present mathematical model is validated with SolTrace model and with the experimental study conducted on a prototype of Fresnel lens with spherical facets fabricated using CO2 laser cutting machine. Focal length for the proposed Fresnel lens with spherical facets is found to be the same. However, concentration ratio computed from the present ray-tracing model is in fair agreement with SolTrace model and experimental data with percentage deviations at focal length 5.4% and 12.4%, respectively. 相似文献
64.
Venugopalan Visha Kumari Purabi Banerjee Vivek Chandra Verma Suvana Sukumaran Malamal Alickal Sarath Chandran Kodigal A. Gopinath Govindarajan Venkatesh Sushil Kumar Yadav Vinod Kumar Singh Neeraj Kumar Awasthi 《International journal of molecular sciences》2022,23(15)
By the year 2050, the world’s population is predicted to have grown to around 9–10 billion people. The food demand in many countries continues to increase with population growth. Various abiotic stresses such as temperature, soil salinity and moisture all have an impact on plant growth and development at all levels of plant growth, including the overall plant, tissue cell, and even sub-cellular level. These abiotic stresses directly harm plants by causing protein denaturation and aggregation as well as increased fluidity of membrane lipids. In addition to direct effects, indirect damage also includes protein synthesis inhibition, protein breakdown, and membranous loss in chloroplasts and mitochondria. Abiotic stress during the reproductive stage results in flower drop, pollen sterility, pollen tube deformation, ovule abortion, and reduced yield. Plant nutrition is one of the most effective ways of reducing abiotic stress in agricultural crops. In this paper, we have discussed the effectiveness of different nutrients for alleviating abiotic stress. The roles of primary nutrients (nitrogen, phosphorous and potassium), secondary nutrients (calcium, magnesium and sulphur), micronutrients (zinc, boron, iron and copper), and beneficial nutrients (cobalt, selenium and silicon) in alleviating abiotic stress in crop plants are discussed. 相似文献
65.
Kamlendra Awasthi V. Kulshrestha Rashi Nathawat N.K. Acharya M. Singh D.K. Avasthi Y.K. Vijay 《Polymer Bulletin》2006,57(5):723-728
Summary The preparation of conical pores in polyethylene terepthlate (PET) membrane is described. The conical pores prepared in PET
by track etching technique. For this purpose, Cl9+ ion irradiated film was placed into an electrolytic cell and etched from one side while other side of membrane was protected
by a stopping medium. During etching, current was recorded as a function of time, which shows a sudden change, indicating
the pores breakthrough. After breakthrough, the etch process is interrupted by replacing the etching solution. After etching,
the current voltage characteristics were determined under symmetric bath conditions. The resulting conical pores show non
ohmic behavior, similar to that of an electronic diode. 相似文献
66.
67.
Viscous Potential Flow Analysis of Nonlinear Rayleigh–Taylor Instability with Heat and Mass Transfer
Mukesh Kumar Awasthi Rishi Asthana G. S. Agrawal 《Microgravity science and technology》2012,24(5):351-363
The nonlinear analysis of Rayleigh?CTaylor instability of two viscous fluids is studied when there is heat and mass transfer across the interface, using viscous potential flow theory. The fluids are considered to be viscous and incompressible with different kinematic viscosities. The analysis is based on the method of multiple scale perturbation and the nonlinear stability is governed by first-order nonlinear partial differential equation. The stability conditions are obtained and stability is discussed theoretically as well as numerically. Regions of stability and instability have been shown graphically indicating the effect of various parameters. It has been observed that the heat and mass transfer has stabilizing effect on the stability of the system in the nonlinear analysis. 相似文献
68.
Polyolefins are the largest class of commercially available synthetic polymers that are extensively used in a variety of applications from commodities to engineering owing to their low cost of production, good physico-mechanical properties, light weight, good processability, and recyclability. Compared to conventional molding techniques, fused deposition modeling (FDM)-based 3D printing is a smart manufacturing technology for thermoplastics due to its low cost, ease of production of complex geometrical parts, rapid prototyping, and scalable customization. FDM 3D printing can be an ideal manufacturing technology for polyolefins to manufacture various complex parts. However, FDM 3D-printing of polyolefins is challenged bycritical printing problems like high warpage, dimensional inaccuracies, poor bed adhesion, and poor layer-to-layer adhesion. In this review, a fundamental understanding of polyolefins and their FDM 3D-printing process is established, and the recent progress of FDM 3D printing of polyolefins is summarized. Furthermore, strategies to overcome warpage and to improve mechanical strength of the 3D-printed polyolefins are provided. Finally, future prospectives of FDM 3D-printing of polyolefins are critically discussed to inspire prospective research in this field. It is believed that this review article can be tremendously useful for research work related to FDM of polyolefin-based materials. 相似文献
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