Papers by manoranjan kumar
Silicon nitride based fluidically tuned photonic crystal for bio-sensing application
SPIE Micro + Nano Materials, Devices, and Applications 2019
In this work, silicon nitride (Si3N4) based fluidically tuned photonic crystal for a biosensing a... more In this work, silicon nitride (Si3N4) based fluidically tuned photonic crystal for a biosensing application is presented. The optical structure is designed on Si3N4 on insulator. The Si3N4 on insulator substrate is found to be one of the most promising materials for the design of bio- sensor at short wavelength. At short wavelength Si3N4 material is found to be most promising material for optical integrated circuits. The structure of the sensor consists of Silicon nitride input and output waveguides separated by a fluidically tuned photonic crystal. Fluidically tuned photonic crystal acts as a sensing region. The sensitivity is based on refractive index of fluidically tuned photonic crystal. The proposed sensor is designed to operate in the visible wavelength range of 660nm. Fluidically tuned photonic crystal consists of rectangular photonic crystal array. The holes of photonic crystal are approximately 160nm in diameter and height is 200nm. Organic light emitting diode is used as an optical source. OLED is coupled to input waveguide. The PDMS microfluidic channel is moulded on the rectangular photonic crystal structure. The structure is modelled and analysis is carried out by using Lumerical mode solution and Lumerical Finite Difference Time Domain (FDTD) simulation tools. Such devices if fabricated can be employed for early detection of various diseases related to pathological parameters.
Quantum phases and thermodynamics of a frustrated spin-1/2 ladder with alternate Ising–Heisenberg rung interactions
Journal of Physics: Condensed Matter, 2021
We study a frustrated two-leg spin ladder with alternate isotropic Heisenberg and Ising rung exch... more We study a frustrated two-leg spin ladder with alternate isotropic Heisenberg and Ising rung exchange interactions, whereas, interactions along legs and diagonals are Ising-type. All the interactions in the ladder are anti-ferromagnetic in nature and induce frustration in the system. This model shows four interesting quantum phases: (i) stripe rung ferromagnetic (SRFM), (ii) stripe rung ferromagnetic with edge singlet (SRFM-E), (iii) anisotropic antiferromagnetic (AAFM), and (iv) stripe leg ferromagnetic (SLFM) phase. We construct a quantum phase diagram for this model and show that in stripe rung ferromagnet (SRFM), the same type of sublattice spins (either isotropic S-type or discrete anisotropic σ-type spins) are aligned in the same direction. Whereas, in anisotropic antiferromagnetic phase, both S and σ-type of spins are anti-ferromagnetically aligned with each other, two nearest S spins along the rung form an anisotropic singlet bond whereas two nearest σ spins form an Ising bo...
Physical Review B, 2006
In conformal field theory, key properties of spin-1/2 chains, such as the ground state energy per... more In conformal field theory, key properties of spin-1/2 chains, such as the ground state energy per site and the excitation gap scale with dimerization δ as δ with known exponents α and logarithmic corrections. The logarithmic corrections vanish in a spin chain with nearest (J=1) and next nearest neighbor interactions (J2), for J2c=0.2411. DMRG analysis of a frustrated spin chain with no logarithmic corrections yields the field theoretic values of α, and scaling relation is valid up to the physically realized range, δ ~ 0.1. However, chains with logarithmic corrections (J2<0.2411J) are more accurately fit by simple power laws with different exponents for physically realized dimerizations. We show the exponents decreasing from approximately 3/4 to 2/3 for the spin gap and from approximately 3/2 to 4/3 for the energy per site and error bars in the exponent also decrease as J2 approaches to J2c. PACs number: 75.10.Pq, 75.10.Jm The linear Heisenberg antiferromagnet (HAF) of spin-1/2 si...
Sustainable and Efficient CuI-NPs-Catalyzed Cross-Coupling Approach for the Synthesis of Tertiary 3-Aminopropenoates, Triazoles, and Ciprofloxacin
Asian Journal of Organic Chemistry, 2018
Physical Review B, 2019
We study an isotropic Heisenberg spin-1/2 model on a trellis ladder which is composed of two J1 −... more We study an isotropic Heisenberg spin-1/2 model on a trellis ladder which is composed of two J1 − J2 zigzag ladders interacting through anti-ferromagnetic rung coupling J3. The J1 and J2 are ferromagnetic zigzag spin interaction between two legs and antiferromagnetic interaction along each leg of a zigzag ladder. A quantum phase diagram of this model is constructed using the density matrix renormalization group (DMRG) method and linearized spin wave analysis. In small J2 limit a short range striped collinear phase is found in the presence of J3, whereas, in the large J2/J3 limit non-collinear quasi-long range phase is found. The system shows a short range non-collinear state in large J3 limit. The short range order phase is the dominant feature of this phase diagram. We also show that the results obtained by DMRG and linearized spin wave analysis show similar phase boundary between collinear striped and non-collinear short range phases, and the collinear phase region shrinks with increasing J3. We apply this model to understand the magnetic properties of CaV2O5 and also fit the experimental data of susceptibility and magnetization. We note that J3 is a dominant interaction in this material, whereas J1 and J2 are approximately half of J3. The variation of magnetic specific heat capacity as a function of temperature for various external magnetic fields is also predicted.
Applied Physics Letters, 2019
Modeling and simulation of opto-fluidic based Mach-Zehnder interferometer for biosensing application
2015 Workshop on Recent Advances in Photonics (WRAP), 2015
In this paper, the integrated optical Mach-Zehnder Interferometer (IO-MZI) is designed for Biosen... more In this paper, the integrated optical Mach-Zehnder Interferometer (IO-MZI) is designed for Biosensing application. A sensor arm with optical sensor with a liquid core waveguide in one of the optical path is considered for a Mach-Zehnder Interferometer. In this work an Integrated optical Mach-Zehnder Interferometeric biosensor is proposed for Rapid diagnostic test (RDT). The design of IO-MZI is done using COMSOL software.
2016 IEEE International Conference on Recent Trends in Electronics, Information & Communication Technology (RTEICT), 2016
Images are considered for handling in different fields. The paper has an algorithm to guard the k... more Images are considered for handling in different fields. The paper has an algorithm to guard the key image whose privacy must be kept up and verify the dealer who needs to disseminate that key image to a numerous clients. For authentication purpose the key image and palm-print of dealer are fused. In this paper Dual Tree Discrete Wavelet Transform is applied on both key image and palm print, coefficients obtained from both images are being fused using Image Fusion technique. DTDWT is used to overcome the drawbacks of DWT. Image fusion is a strategy or a procedure of consolidating pertinent data from set of pictures into a solitary picture, the resultant picture got will be more finished and useful than the information pictures. The threshold secret sharing is used to distribute the fused image to many shares. This gives both privacy as well as verification about the dealer whoever sends the image. During decryption key image is known and the palm print of the dealer has to be reconstructed from the shares collected from authorized users, finally verification is done.
Physical Review B, 2016
An efficient density matrix renormalization group (DMRG) algorithm is presented and applied to Y-... more An efficient density matrix renormalization group (DMRG) algorithm is presented and applied to Y-junctions, systems with three arms of n sites that meet at a central site. The accuracy is comparable to DMRG of chains. As in chains, new sites are always bonded to the most recently added sites and the superblock Hamiltonian contains only new or once renormalized operators. Junctions of up to N = 3n + 1 ≈ 500 sites are studied with antiferromagnetic (AF) Heisenberg exchange J between nearest-neighbor spins S or electron transfer t between nearest neighbors in halffilled Hubbard models. Exchange or electron transfer is exclusively between sites in two sublattices with NA = NB. The ground state (GS) and spin densities ρr =< S z r > at site r are quite different for junctions with S = 1/2, 1, 3/2 and 2. The GS has finite total spin SG = 2S(S) for even (odd) N and for MG = SG in the SG spin manifold, ρr > 0(< 0) at sites of the larger (smaller) sublattice. S = 1/2 junctions have delocalized states and decreasing spin densities with increasing N. S = 1 junctions have four localized Sz = 1/2 states at the end of each arm and centered on the junction, consistent with localized states in S = 1 chains with finite Haldane gap. The GS of S = 3/2 or 2 junctions of up to 500 spins is a spin density wave (SDW) with increased amplitude at the ends of arms or near the junction. Quantum fluctuations completely suppress AF order in S = 1/2 or 1 junctions, as well as in half-filled Hubbard junctions, but reduce rather than suppress AF order in S = 3/2 or 2 junctions.
Journal of Metallurgy, 2015
Steel Melting Shop-I, Rourkela Steel Plant, Rourkela, produces 0.5 MT of various special steels t... more Steel Melting Shop-I, Rourkela Steel Plant, Rourkela, produces 0.5 MT of various special steels through BOF-VAR/VOR-LF-CC route. One of the most serious problems in BOF operations was lance skulling, hood jamming, and build-up of metal in the mouth and cone of the furnace due to spitting and slopping. As spitting occurring during blowing increases, these particles of metal are deposited inside the mouth and cone and affect badly BOF productivity. In the present work, control of spitting has been established by addition of sinter during the period of spitting. It also helped to improve the slag formation and fluidity of slag through increase of FeO content during peak decarburisation period.
Physical Review B, 2014
It is of significant technological interest to have an understanding of cooperativity in spin-cro... more It is of significant technological interest to have an understanding of cooperativity in spin-crossover phenomena observed in metalorganic polymeric complexes. Microscopic origin of this cooperativity has been discussed in literature primarily in terms of elastic interactions. Through Monte Carlo simulation of the model Hamiltonian we show that the superexchange interactions between localized magnetic moments at spin-crossover sites can play a crucial role in cooperativity, depending on the nature of the elastic interactions. While in the case of the effective elastic interaction of ferroelastic nature, inclusion of the above-mentioned exchange interaction produces quantitative changes in the hysteresis loop, for effective elastic interaction of antiferroelastic nature, the existence of hysteresis is found to be dictated entirely by the magnetic exchange interaction. Considering the example of a real material, namely Fe-triazole, employing the material-specific density functional theory calculation, we show the later scenario to be true for these systems. Our study should motivate further investigation on the role of magnetic exchanges in metalorganic polymers.
The frustrated isotropic J1 − J2 model with ferromagnetic J1 and anti-ferromagnetic J2 interactio... more The frustrated isotropic J1 − J2 model with ferromagnetic J1 and anti-ferromagnetic J2 interactions in presence of an axial magnetic field shows many exotic phases, such as vector chiral and multipolar phases. The existing studies of the phase boundaries of these systems are based on the indirect evidences such as correlation functions etc. In this paper, the phase boundaries of these exotic phases are calculated based on order parameters and jumps in the magnetization. In the strong magnetic field, Z2 symmetry is broken, therefore, order parameter of the vector chiral phase is calculated using the broken symmetry states. Our results obtained using the modified density matrix renormalization group and exact diagonalization methods, suggest that the vector chiral phase exist only in narrow range of parameter space J2/J1.
In silico targeted genome mining and comparative modelling reveals a putative protein similar to an Arabidopsis drought tolerance DNA binding transcription factor in Chromosome 6 of Sorghum bicolor genome
Interdisciplinary Sciences: Computational Life Sciences, 2012
Arabidopsis Thaliana HARDY (AtHRD) is a gene with an APETELA 2 / Ethylene Responsive Factor (AP2/... more Arabidopsis Thaliana HARDY (AtHRD) is a gene with an APETELA 2 / Ethylene Responsive Factor (AP2/ERF) domain linked to improved performance under drought in rice. We hypothesized that the sorghum genome could possess a similar gene product and were motivated to conduct a computational genome scale mining for the protein and analyse its structural and functional properties. AtHRD sequence was used as a query to BLAST against the sorghum genome dataset followed by multiple alignment analysis. A homology model of the target was built using a template detected based on the pair-wise comparison of hidden Markov models for alignments. DNA docking with a matrix of homologous interface contacts was done. Functional and structural analysis of the query and target was conducted using various online servers. A High-scoring segment pair from Chromosome 6 of the sorghum genome in the region between 54948120 and 54948668 had 68 amino acid similarities out of the 184 residues and was 1.4% above twilight zone threshold. The homology model showed 86.8% residues in most favoured regions. The target protein which had an AP2/ERF domain when docked with GCC box DNA motif had conserved residues involved in binding; it had a long unstructured region beyond the AP2 domain with several motifs for the recognition of serine/threonine protein kinase group. The protein model showed that it could bind to a GCC box which is present in several drought responsive genes. The presence of possible signalling domains and intrinsic disorder in the target protein suggest that this could play a role in drought tolerance which is an inherent character of sorghum. These results offer a jumpstart for validation experiments which could pave the way for cis/trans genic improvement of a range of crops.
The Journal of organic chemistry, Jan 3, 2014
Vasicine, an abundantly available quinazoline alkaloid from the leaves of Adhatoda vasica, has be... more Vasicine, an abundantly available quinazoline alkaloid from the leaves of Adhatoda vasica, has been successfully employed for metal- and base-free reduction of nitroarenes to the corresponding anilines in water. The method is chemoselective and tolerates a wide range of reducible functional groups, such as ketones, nitriles, esters, halogens, and heterocyclic rings. Dinitroarenes reduced selectively to the corresponding nitroanilines under the present reaction conditions.
IOSR Journal of Computer Engineering, 2014
Cloud computing is the convergence of virtualization, Distributed Applications, Grid, Maturity of... more Cloud computing is the convergence of virtualization, Distributed Applications, Grid, Maturity of enterprise software application and enterprise IT Management. It is a tremendously attractive technology as it enables a fundamental shift from capital intensive focus to a flexible operational management model. Basically it is characterized by on demand computing, based on pay per use pricing model. This technology enables the user to use the system without the need to know the physical location and configuration of the system that delivers the services. At the same time it also offers participation of less manpower and zero maintenance of the services. This paper is based on the description of cloud computing technology and its numerous benefits. Furthermore this paper also highlights the Environment of Cloud Computing and Consideration on Cloud Adoption.
Vasicine catalyzed direct C–H arylation of unactivated arenes: organocatalytic application of an abundant alkaloid
Tetrahedron Letters, 2013
ABSTRACT
Physical Review B, 2013
The quantum phases of one-dimensional spin s = 1/2 chains are discussed for models with two param... more The quantum phases of one-dimensional spin s = 1/2 chains are discussed for models with two parameters, frustrating exchange g = J2 > 0 between second neighbors and normalized nonfrustrating power-law exchange with exponent α and distance dependence r −α. The ground state (GS) at g = 0 has long-range order (LRO) for α < 2, long-range spin fluctuations for α > 2. The models conserve total spin S = SA + SB, have singlet GS for any g, α ≥ 0 and decouple at 1/g = 0 to linear Heisenberg antiferromagnets on sublattices A and B of odd and even-numbered sites. Exact diagonalization of finite chains gives the sublattice spin S 2 A , the magnetic gap Em to the lowest triplet state and the excitation Eσ to the lowest singlet with opposite inversion symmetry to the GS. An analytical model that conserves sublattice spin has a first order quantum transition at gc = 1/4ln2 from a GS with perfect LRO to a decoupled phase with SA = SB = 0 for g ≥ 4/π 2 and no correlation between spins in different sublattices. The model with α = 1 has a first order transition to a decoupled phase that closely resembles the analytical model. The bond order wave (BOW) phase and continuous quantum phase transitions of finite models with α ≥ 2 are discussed in terms of GS degeneracy where Eσ(g) = 0, excited state degeneracy where Eσ(g) = Em(g), and S 2 A. The decoupled phase at large frustration has nondegenerate GS for any exponent α and excited states related to sublattice excitations.
Physical Review B, 2009
Theoretical and computational studies of the quantum phase diagram of the one-dimensional half-fi... more Theoretical and computational studies of the quantum phase diagram of the one-dimensional half-filled extended Hubbard model (EHM) indicate a narrow bond order wave (BOW) phase with finite magnetic gap Em for on-site repulsion U < U * , the critical point, and nearest neighbor interaction Vc ≈ U/2 near the boundary of the charge density wave (CDW) phase. Potentials with more extended interactions that retain the EHM symmetry are shown to have a less cooperative CDW transition with higher U * and wider BOW phase. Density matrix renormalization group (DMRG) is used to obtain Em directly as the singlet-triplet gap, with finite Em marking the BOW boundary Vs(U). The BOW/CDW boundary Vc(U) is obtained from exact finite-size calculations that are consistent with previous EHM determinations. The kinetic energy or bond order provides a convenient new estimate of U * based on a metallic point at Vc(U) for U < U *. Tuning the BOW phase of half-filled Hubbard models with different intersite potentials indicates a ground state with large charge fluctuations and magnetic frustration. The possibility of physical realizations of a BOW phase is raised for Coulomb interactions.
Physical Review B, 2012
Exact diagonalization of finite spin-1/2 chains with periodic boundary conditions is applied to t... more Exact diagonalization of finite spin-1/2 chains with periodic boundary conditions is applied to the ground state (gs) of chains with ferromagnetic (F) exchange J1 < 0 between first neighbors, antiferromagnetic (AF) exchange J2 = αJ1 > 0 between second neighbors, and axial anisotropy 0 ≤ ∆ ≤ 1. In zero field, the gs is in the Sz = 0 sector for the relevant parameters and is doubly degenerate at multiple points γm = (αm, ∆m) in the α, ∆ plane. Degeneracy under inversion at sites or spin parity or both leads, respectively, to a bond order wave (BOW), to staggered magnetization or to vector chiral (VC) order. Exact results up to N = 28 spins directly yield order parameters and spin correlation functions whose weak N dependencies allow inferences about infinite chains. The high-spin gs at J2 = 0 changes discontinuously at γ1 = (−1/4, 1) to a singlet in the isotropic (∆ = 1) chain. The transition from high to low spin S(α, ∆) is continuous for ∆ < ∆B = 0.95 ± 0.01 on the degeneracy line α1(∆). The gs has staggered magnetization between ∆A = 0.72 and ∆B, and a BOW for ∆ < ∆A. When both inversion and spin parity are reversed at γm, the correlation functions C(p) for spins separated by p sites are identical. C(p) minima are shifted by π/2 from the minima of VC order parameters at separation p, consistent with right and left-handed helices along the z axis and spins in the xy plane. Degenerate gs of finite chains are related to quantum phase diagrams of extended α, ∆ chains, with good agreement for order parameters along the line α1(∆). Degenerate gs limit a VC phase to intermediate α and ∆ where S(α, ∆) varies rapidly but continuously, in contrast to many-body treatments in which VC phases extend over a larger range of parameters.
Physical Review B, 2007
In conformal field theory, key properties of spin-1/2 chains, such as the ground state energy per... more In conformal field theory, key properties of spin-1/2 chains, such as the ground state energy per site and the excitation gap scale with dimerization δ as δ α with known exponents α and logarithmic corrections. The logarithmic corrections vanish in a spin chain with nearest (J=1) and next nearest neighbor interactions (J 2), for J 2c =0.2411. DMRG analysis of a frustrated spin chain with no logarithmic corrections yields the field theoretic values of α, and scaling relation is valid up to the physically realized range, δ ~ 0.1. However, chains with logarithmic corrections (J 2 <0.2411J) are more accurately fit by simple power laws with different exponents for physically realized dimerizations. We show the exponents decreasing from approximately 3/4 to 2/3 for the spin gap and from approximately 3/2 to 4/3 for the energy per site and error bars in the exponent also decrease as J 2 approaches to J 2c .
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Papers by manoranjan kumar