CFD Modeling of Three-phase Bubble Column: 1. Study of Flow Pattern

Bubble column (BC) or slurry bubble column (SBC) reactor has emerged as one of the most promising devices in chemical, biochemical and environmental engineering operations because of its simple construction, isothermal conditions, high heat and mass transfer rates, and on-line catalyst addition and withdrawal. The present work has been carried out to characterize the dynamics of three-phase flow in cylindrical bubble column, run under homogeneous bubble flow and heterogeneous flow conditions using CFD (Computational Fluid Dynamics) simulation. Investigation has been done to study the flow pattern of three-phase bubble column along with parametric studies. The simulations were performed for air-water-glass beads in a bubble column of 0.6m height, 0.1m i.d. and 0.05m sparger diameter to study the flow pattern. Eulerian-Eulerian three-phase simulations with k-ε turbulence for liquid phase were carried out using the commercial flow simulation software CFX-5.6, with a focus on characterizing the dynamics properties of gas liquid solid flows. The model has been validated using available experimental data and is in good agreement. Detail study of the flow pattern in three-phase bubble column has been carried out and flow pattern has been presented in the form of contour and vector plots. The results presented are useful for understanding the dynamics of gas liquid solid flows in bubble column and provide a basis for further development of CFD model for three phase systems

CFD Modeling of Three-Phase Bubble Column: 2. Effect of Design Parameters

The effect of design parameters on the flow pattern in a three-phase bubble column by means of Computational Fluid Dynamics (CFD) has been studied. The simulations were performed for air-water-glass beads in a bubble column of H = 0.6m, D = 0.1m and ds = 0.05m to study the flow pattern. Eulerian-Eulerian three-phase simulations with k-ε turbulence for liquid phase were carried out using the commercial flow simulation software CFX-5.6, with a focus on characterizing the dynamics properties of gas liquid solid flows. The model has been validated using available experimental data and is in good agreement. Effect of design quantities such as: H/D ratio, sparger diameter, taperness on the flow pattern has been studied. The results presented are useful for understanding the dynamics of gas liquid solid flows in bubble column and provide a basis for further development of CFD model for three-phase system

Identification of a non-redundant set of 202 in silico SSR markers and applicability of a select set in chickpea (Cicer arietinum L.)

The paucity of sequence information flanking the simple sequence repeat (SSR) motifs identified especially in the transcript sequences has been limiting factor in the development of SSR markers for plant genome analysis as well as breeding applications. To overcome this and enhance the genic SSR marker repertoire in chickpea, the draft genome sequence of kabuli chickpea (CDC Frontier) and publicly available transcript sequences consisting of in silico identified SSR motifs were deployed in the present study. In this direction, the 300 bp sequence flanking the SSR motifs were retrieved by aligning 566 SSR containing transcripts of ICCV 2 available in public domain on the reference chickpea genome. A set of 202 novel genic SSRs were developed from a set of 507 primer pairs designed, based on in silico amplification of single locus and having no similarity to the publicly available SSR markers. Further, 40 genic SSRs equally distributed on chickpea genome were validated on a select set of 44 chickpea genotypes (including 41 Cicer arietinum and 3 Cicer reticulatum), out of which 25 were reported to be polymorphic. The polymorphism information content (PIC) value of 25 polymorphic genic SSRs ranged from 0.11 to 0.77 and number of alleles varied from 2 to 9. Clear demarcation among founder lines of multi-parent advanced generation inter-cross (MAGIC) population developed at ICRISAT and near-isogenic nature of JG 11 and JG11 + demonstrates the usefulness of these markers in chickpea diversity analysis and breeding studies. Further, genic polymorphic SSRs reported between parental lines of 16 different mapping populations along with the novel SSRs can be deployed for trait mapping and breeding applications in chickpea

Coherent spin radiation by magnetic nanomolecules and nanoclusters

The peculiarities of coherent spin radiation by magnetic nanomolecules is investigated by means of numerical simulation. The consideration is based on a microscopic Hamiltonian taking into account realistic dipole interactions. Superradiance can be realized only when the molecular sample is coupled to a resonant electric circuit. The feedback mechanism allows for the achievement of a fast spin reversal time and large radiation intensity. The influence on the level of radiation, caused by sample shape and orientation, is analysed. The most powerful coherent radiation is found to occur for an elongated sample directed along the resonator magnetic field.Comment: Latex file, 11 figure

Experimental design, modeling and mechanism of cationic dyes biosorption on to magnetic chitosan-lutaraldehyde composite

Magnetic separation of toxic dyes has become a potential and effective method in wastewater treatments. In present research, a facile in situ one step co-precipitation synthetic approach is used to develop water-dispersible Fe 3 O 4 /Chitosan/Glutaraldehyde nanocomposites (MCS-GA) as an efficient adsorbent for the removal of Crystal Violet (CV) from aqueous solution. The physicochemical properties of the MCS-GA were investigated using FTIR, SEM, TEM, XRD, BET, and VSM techniques. 5-level and 3-factors central composite design (CCD) combined with the response surface methodology (RSM) was applied to investigate the statistical relationships between independent variables i.e. initial pH, adsorbent dosage, initial dye concentration and adsorption process as response. The optimal values of the parameters for the best efficiency (99.99) were as follows: pH of 11, the initial dye concentration of 60 mg L �1 and MCS-GA dosage of 0.817 g L �1 , respectively. The adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (q max : 105.467 mg g �1 , R 2 : 0.996) and pseudo-second order kinetics (R 2 : 0.960). Thermodynamic parameters (R 2 > 0.941, �H°: 690.609�896.006 kJ mol �1 , �G°: �1.6849 to �13.4872 kJ mol �1 , �S°: 0.168�0.232 kJ mol �1 K �1 ) also indicated CV adsorption is feasible, spontaneous and endothermic in nature. Overall, taking into account the excellent efficiency, good regeneration and acceptable performance in real terms, MCS-GA can be introduced as a promising absorbent for dyes removal from the textile wastewater. © 2019 Elsevier B.V

Model-based Cross-correlation Search for Gravitational Waves from the Low-mass X-Ray Binary Scorpius X-1 in LIGO O3 Data

Published 2022 December 16We present the results of a model-based search for continuous gravitational waves from the low-mass X-ray binary Scorpius X-1 using LIGO detector data from the third observing run of Advanced LIGO and Advanced Virgo. This is a semicoherent search that uses details of the signal model to coherently combine data separated by less than a specified coherence time, which can be adjusted to balance sensitivity with computing cost. The search covered a range of gravitational-wave frequencies from 25 to 1600 Hz, as well as ranges in orbital speed, frequency, and phase determined from observational constraints. No significant detection candidates were found, and upper limits were set as a function of frequency. The most stringent limits, between 100 and 200 Hz, correspond to an amplitude h0 of about 10⁻²⁵ when marginalized isotropically over the unknown inclination angle of the neutron star’s rotation axis, or less than 4 × 10⁻²⁶ assuming the optimal orientation. The sensitivity of this search is now probing amplitudes predicted by models of torque balance equilibrium. For the usual conservative model assuming accretion at the surface of the neutron star, our isotropically marginalized upper limits are close to the predicted amplitude from about 70 to 100 Hz; the limits assuming that the neutron star spin is aligned with the most likely orbital angular momentum are below the conservative torque balance predictions from 40 to 200 Hz. Assuming a broader range of accretion models, our direct limits on gravitational-wave amplitude delve into the relevant parameter space over a wide range of frequencies, to 500 Hz or more.R. Abbott ... D. Beniwal ... G. N. Bolingbroke ... D. D. Brown ... H. Cao ... A. A. Ciobanu ... Z. J. Holmes ... K. Jenner ... J. Munch ... S. Muusse ... S. W. S. Ng ... D. J. Ottaway ... M. Pathak ... T. J. Roocke ... M. G. Schiworski ... P. J. Veitch ... et al. (The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration

First joint observation by the underground gravitational-wave detector KAGRA with GEO 600

Published April 30, 2022We report the results of the first joint observation of the KAGRA detector with GEO 600. KAGRA is a cryogenic and underground gravitational-wave detector consisting of a laser interferometer with 3 km arms, located in Kamioka, Gifu, Japan. GEO 600 is a British–German laser interferometer with 600 m arms, located near Hannover, Germany. GEO 600 and KAGRA performed a joint observing run from April 7 to 20, 2020. We present the results of the joint analysis of the GEO–KAGRA data for transient gravitational-wave signals, including the coalescence of neutron-star binaries and generic unmodeled transients. We also perform dedicated searches for binary coalescence signals and generic transients associated with gamma-ray burst events observed during the joint run. No gravitational-wave events were identified. We evaluate the minimum detectable amplitude for various types of transient signals and the spacetime volume for which the network is sensitive to binary neutron-star coalescences. We also place lower limits on the distances to the gamma-ray bursts analyzed based on the non-detection of an associated gravitational-wave signal for several signal models, including binary coalescences. These analyses demonstrate the feasibility and utility of KAGRA as a member of the global gravitational-wave detector network.The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration, R. Abbott ... D. Beniwal ... G. N. Bolingbroke ... D. D. Brown ... H. Cao ... A. A. Ciobanu ... Z. J. Holmes ... K. Jenner ... J. Munch ... S. Muusse ... S. W. S. Ng ... D. J. Ottaway ... M. Pathak ... M. G. Schiworski ... P. J. Veitch ... et al