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3 results on '"Alwin Michael"'

1. Diffusion-Slip Boundary Conditions for Isothermal Flows in Micro- and Nano-Channels

Author

Alwin Michael Tomy and S. Kokou Dadzie

Subjects
diffusion slip, volume diffusion, micro- and nano-channels, Mechanical engineering and machinery, TJ1-1570
Abstract

Continuum description of flows in micro- and nano-systems requires ad hoc addition of effects such as slip at walls, surface diffusion, Knudsen diffusion and others. While all these effects are derived from various phenomenological formulations, a sound theoretical ground unifying these effects and observations is still lacking. In this paper, adopting the definition and existence of various type of flow velocities beyond that of the standard mass velocity, we suggest derivation of model boundary conditions that may systematically justify various diffusion process occurring in micro- and nano-flows where the classical continuum model breaks down. Using these boundary conditions in conjunction with the classical continuum flow equations we present a unified derivation of various expressions of mass flow rates and flow profiles in micro- and nano-channels that fit experimental data and provide new insights into these flow profiles. The methodology is consistent with recasting the Navier–Stokes equations and appears justified for both gas and liquid flows. We conclude that these diffusion type of boundary conditions may be more appropriate to use in simulating flows in micro- and nano-systems and may also be adapted as boundary condition models in other interfacial flow modelling.

Published
2022
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3. High-frequency plantlet regeneration and multiple shoot induction from cultured immature seeds of Rhynchostylis retusa Blume., an exquisite orchid

Author

Alwin Michael and T. Dennis Thomas

Subjects
Orchidaceae, biology, Rhynchostylis retusa, Plant Science, biology.organism_classification, Plantlet, Horticulture, chemistry.chemical_compound, Murashige and Skoog medium, chemistry, Germination, Seedling, Shoot, Botany, Kinetin, Biotechnology
Abstract

Seeds of an exquisite orchid, Rhynchostylis retusa, germinated in vitro on ½ Murashige and Skoog (MS) medium supplemented with different concentrations of coconut milk (CM). Of the different concentrations of CM employed for seed germination, 15% gave optimum response. On this medium a maximum of 93% cultures produced seedlings 90 days after inoculation. Individual seedlings with a length of about 0.5 cm were subcultured on MS medium supplemented with various concentrations of 6-benzylaminopurine (BA) and α-naphthalene acetic acid (NAA), with or without activated charcoal (AC), for further growth. Seedling growth was maximum on MS medium supplemented with 6 μM BA, 0.2 μM NAA, and 1 g L−1 AC. Here a maximum seedling length of 2.3 cm was observed after 1 month of culture. The seedlings were subcultured on MS medium supplemented with kinetin (Kn) or thidiazuron (TDZ), in the presence or absence of AC, for multiple shoot induction. A maximum multiple shoot number of 8.2 was observed on MS medium supplemented with 2 μM TDZ in the presence of AC. The shoots were rooted on ½ MS medium supplemented with 2 μM indole-3-butyric acid (IBA) and successfully transplanted to soil. Of the 45 plantlets transferred to soil 40 survived. The reproducible protocol standardized here will enable rapid propagation and conservation of this precious orchid.

Published
2007
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