Pradeep K. Jha

Mixing in a tundish and a choice of turbulence model for its prediction

The Navier‐Stokes equation and the species continuity equation have been solved numerically in a boundary fitted coordinate system comprising the geometry of a single strand bare tundish. The solution of the species continuity equation predicts the time evolution of the concentration of a tracer at the outlet of the tundish. The numerical prediction of the tracer concentration has been made with nine different turbulence models and has been compared with the experimental observation for the tundish. It has been found that the prediction from the standard k‐e model, the k‐e Chen‐Kim (ck) and the standard k‐e with Yap correction (k‐e Yap), matches well with that of the experiment compared to the other turbulence models as far as gross quantities like the mean residence time and the ratio of mixed to dead volume are concerned. It has been found that the initial transient development of the tracer concentration is best predicted by the low Reynolds number Lam‐Bremhorst model (LB model) and then by the k‐e RNG model, while these two models under predict the mean residence time as well as the ratio of mixed to dead volume. The Chen‐Kim low Reynolds number (CK low Re) model (with and without Yap correction) as well as the constant effective viscosity model over predict the mixing parameters, i.e. the mean residence time and the ratio of mixed to dead volume. Taking the solution of the k‐e model as a starting guess for the large eddy simulation (LES), a solution for the LES could be arrived after adopting a local refinement of the cells twice so that the near wall y+ could be set lower than 1. Such a refined grid gave a time‐independent solution for the LES which was used to solve the species continuity equation. The LES solution slightly over predicted the mean residence time but could predict fairly well the mixed volume. However, the LES could not predict both the peaks in the tracer concentration like the k‐e, RNG and the Lam‐Bremhorst model. An analysis of the tracer concentration on the bottom plane of the tundish could help to understand the presence of plug and mixed flow in it.

Effect of outlet positions and various turbulence models on mixing in a single and multi strand tundish

The Navier‐Stokes equation and the species continuity equation have been solved numerically in a boundary fitted coordinate system comprising the geometry of a large scale industrial size tundish. The solution of the species continuity equation predicts the time evolution of the concentration of a tracer at the outlet of a single strand bare tundish. The numerical prediction of the tracer concentration has been made with three different turbulence models; (a standard k‐e, a k‐e RNG and a Low Re number Lam‐Bremhorst model) which favorably compares with that of the experimental observation for a single strand bare tundish. It has been found that the overall comparison of k‐e model with that of the experiment is better than the other two turbulence models as far as gross quantities like mean residence time and ratio of mixed to dead volume are concerned. However, it has been found that the initial transient development of the tracer concentration is best predicted by the Lam‐Bremhorst model and then by the R...

An emerging interface between life science and nanotechnology: present status and prospects of reproductive healthcare aided by nano-biotechnology

Among the various applications of nano-biotechnology, healthcare is considered one of the most significant domains. For that possibility to synthesize various kind of nanoparticles (NPs) and the ever-increasing ability to control their size as well as structure, to improve surface characteristics and binding NPs with other desired curing agents has played an important role. In this paper, a brief sketch of various kinds of nanomaterials and their biomedical applications is given. Despite claims of bio-nanotechnology about to touch all areas of medical science, information pertaining to the role of nanotechnology for the betterment of reproductive healthcare is indeed limited. Therefore, the various achievements of nano-biotechnology for healthcare in general have been illustrated while giving special insight into the role of nano-biotechnology for the future of reproductive healthcare betterment as well as current achievements of nanoscience and nanotechnology in this arena.

Employment of different turbulence models to the design of optimum steel flows in a tundish

The Navier‐Stokes equation and the species continuity equation have been solved numerically in a boundary fitted coordinate system comprising the geometry of a large scale industrial size tundish. The solution of the species continuity equation predicts the time evolution of the concentration of a tracer at the outlets of a six strand billet caster tundish. The numerical prediction of the tracer concentration has been made with six different turbulence models (the standard k‐e, the k‐e RNG, the Low Re number Lam‐Bremhorst model, the Chen‐Kim high Re number model (CK), the Chen‐Kim low Re number model (CKL) and the simplest constant effective viscosity model (CEV)) which favorably compares with that of the experimental observation for a single strand bare tundish. It has been found that the overall comparison of the k‐e model, the RNG, the Lam‐Bremhorst and the CK model is much better than the CKL model and the CEV model as far as gross quantities like the mean residence time and the ratio of mixed to dead...

Smart RISUG: a potential new contraceptive and its magnetic field-mediated sperm interaction.

The rationale and technique underlying a novel concept of noninvasive fertility control by a new Cuproferrogel contraceptive drug, iron oxide–copper–styrene maleic anhydride–dimethyl sulphoxide (Fe3O4–Cu–SMA–DMSO) composite named ‘Smart RISUG’ (smart reversible inhibition of sperm under guidance) in presence of pulsed magnetic field (PMF; 1 mT to 800 mT) is explained. It was synthesized by dispersing iron oxide particles and copper particles into SMA-DMSO (male contraceptive RISUG) and characterized for particle distribution, particle size measurement and transmittance peaks, etc. Interaction of the RISUG particles as well as Smart RISUG particles with Albino rat sperm cell was studied in presence as well as absence of PMF. To find an explanation to increased reaching of the Smart RISUG drug into sperm under influence of magnetic field, the transport properties were characterized by high resolution transmission electron microscopy and atomic force microscopy. Smart RISUG could be mobilized into sperm cell membrane at the PMF, 760 mT in about 50 seconds. Adoption of novel drug Smart RISUG involving new technique may open the pathway for non surgical control of drug distribution, detection and restoration of the normal fertility after removal of the contraceptive from the male/female reproductive tube in presence of electromagnetic field.

Correction: Dietary flavone chrysin (5,7-dihydroxyflavone ChR) functionalized highly-stable metal nanoformulations for improved anticancer applications

Nanomaterials of noble metals with unique size, shape and composition receives much attention owing to their versatile functionality in personalized cancer nanomedicine. Chrysin (ChR), a natural anticancer bioflavonoid, emerged as a potential drug therapy for almost all types of cancer, however it has poor solubility and bioavailability. Herein, we report a new approach to formulate biofunctionalized metallic silver (ChR–AgNPs) and gold (ChR–AuNPs) nanoparticles using ChR as a direct bioreductant and capping agent. Size and dispersity of nanoparticles (NPs) were controlled through fixing different reaction conditions such as the temperature, pH, concentration of metal ion, stoichiometric proportion of the reaction mixture and incubation time based on their optical properties and SPR effect in UV-visible spectroscopy. The role of hydroxyl and carbonyl groups in functionalizing the metal ions with ChR was confirmed with Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. It was also substantiated that the oxygen group from ChR donates electrons to metal ion and results in complexation; ionic Ag+ and Au3+ were reduced to Ag0 and Au0 nano-forms. The physiochemical state of obtained NPs was characterized through different exclusive instrumentation, which shows the presence of highly-stable, spherical, crystalline ChR–AgNPs and ChR–AuNPs with an average size of 14 ± 6 nm and 6 ± 2 nm respectively. In vitro anticancer results revealed that the formulated metallic NPs exhibit enhanced cytotoxicity over ChR in the treatment of two different breast carcinoma cell lines (MDA-MB-231 and MDA-MB-468). Furthermore, it was evident that the NPs cause cell death via the induction of apoptosis. A hemolysis assay with human erythrocytes demonstrates good blood biocompatibility of the NPs. Thus, the ChR functionalized metal NPs can be potentially employed as a combinational drug-nano platform for breast cancer therapy.

Green synthesis of silver nanoparticles using Pongamia pinnata seed: Characterization, antibacterial property, and spectroscopic investigation of interaction with human serum albumin

In recent years, green synthesized nanoparticles from plant extract have drawn a great interest due to their prospective nanomedicinal application. This study investigates a proficient, safer, and sustainable way for the preparation of AgNPs using medicinal plant Pongamia pinnata (family: Leguminoseae, species: Pinnata) seeds extract without using any external reducing and stabilizing agent. Both ultraviolet‐visible spectrum at λmax = 439 nm and energy dispersive X‐ray spectra proof the formation of AgNPs. An average diameter of the AgNPs was 16.4 nm as revealed from transmission electron microscope. Hydrodynamic size (d = ~19.6 nm) was determined by dynamic light scattering (DLS). Zeta potential of AgNPs was found to be −23.7 mV, which supports its dispersion and stability. Fourier transform infrared study revealed that the O ─ H, C ═ O, and C‐O‐C groups were responsible for the formation of AgNPs. The antibacterial activity of the synthesized AgNPs was checked against Escherichia coli ATCC 25922. AgNPs at its LD50 dose exhibited synergistic effect with ampicillin. Because protein‐AgNPs association greatly affects its adsorption, distribution, and functionality and can also influence the functions of biomolecules. So in order to understand the adsorption and bioavailability, we investigated by fluorescence, ultraviolet‐visible, and circular dichroism spectroscopic methods the interaction of synthesized AgNPs toward human serum albumin. The binding affinity and binding sites of human serum albumin toward AgNPs were measured by using the fluorescence quenching data. The circular dichroism spectroscopic results revealed that there was a negligible change of α‐helical content in their native structure. Overall, these AgNPs show versatile biological activities and may be applied in the field of nanomedicine.

Entropy in good manufacturing system: Tool for quality assurance

It has been customary to implement Good Manufacturing Practices (GMP) in pharmaceutical organizations as a systematic and comprehensive quality approach and sometimes by regulatory enforcement. In this scenario, determination of the obvious entropy/disorder arising during the implementation has not been taken care of yet. Therefore, this paper gives the basis for applying query and visual perception of GMP system driven visualization approach, particularly the Laplace equation, to the determination of disorder and deviation pattern inside the GMP system applied in the organization. In this study, a three-dimensional mesh approached with raw and intermediate input handled under GMP parameter is considered to produce high quality products with minimum entropy (variation distribution) by adding the analogy wise different GMP parameters and process variables with Gauss Seidel iteration and thus producing visual picture of the entire system. The approximation involved in applying the equations to the GMP compliant aseptic region was analyzed. Using numerical technique and computer program, the Gauss Seidel iteration equations have been solved with appropriate GMP parameter and process variable. The result indicates that deviations vary over the GMP compliant system and that the process entropy affects the totality of disorderness. Experiments with model of GMP compliant reproductive medicine laboratory confirm that the new method provides optimal manufacturing maintaining GMP and high product quality through the visual representation of the entire system and activity to bring into notice the deviations.

An approach to noninvasive delivery, biodistribution, and fertility control potential evaluation of the Cuproferrogel iron oxide-copper-styrene maleic anhydride-dimethyl sulphoxide in the female

Under guidance of an external pulsed magnetic field the Cuproferrogel iron oxide-copper-styrene maleic anhydride-dimethyl sulphoxide delivered into the rat/rabbit oviduct resulted in oocytes with granulated cytoplasm, zona enlargement, membrane disintegration, and finally loss of viability in 72 hours. Also, the percentage biodistribution of magnetic and electrically conductive particles observed under safe level advocates the use of Cuproferrogel as a potential female fertility control molecule.

Spectroscopic investigation on interaction of biogenic, Croton bonplandianum leaves extract mediated potential bactericidal silver nanoparticles with human hemoglobin and human serum albumin

The green synthesis of nanoparticles has received increasing attention due to the growing demand to produce safe, cost-effective, and eco-friendly technology for nanomaterials synthesis. We report on the use of aqueous Croton bonplandianum (Family: Euphorbiaceae, Genus: Croton) leaves extract for the preparation of silver nanoparticles (AgNPs) without using any external reducing and stabilizing agent. Ultraviolet–visible spectroscopy showed maximum absorbance at 446 nm due to surface plasmon resonance of AgNPs. Energy dispersive X-ray spectra also supported the existence of AgNPs. An average diameter (d = ~17.4 nm) of the spherical AgNPs was determined from the transmission electron microscopic images. Hydrodynamic size (d = ~21.1 nm) was determined by dynamic light scattering. Fourier transform infrared analysis designed that the functional groups like O–H, N–H, , CONH2, and COOH participated in the AgNPs formation. The negative zeta potential value (−19.3 mV) of the AgNPs indicated its dispersion and stability. The AgNPs exhibited strong antibacterial activity against Escherichia coli ATCC 25922 and 1.5 nM proved to be minimum inhibitory concentration for it. Hemolysis assay demonstrated the blood compatibility of the AgNPs toward human RBCs. The binding affinity of the AgNPs toward human hemoglobin and human serum albumin (HSA) was also determined by means of fluorescence spectroscopy. The circular dichroism spectroscopy revealed that the native structures of human hemoglobin and HSA remain unchanged, but its secondary structures were slightly changed upon interaction with AgNPs. Overall, it can be concluded that the AgNPs may be applied in the area of nanomedicines.