Convection in a Krogh cylinder: Putting back fluid flow in the extravascular tissue

Models for drug delivery are based on the use of stirred tanks to represent organs that contain no mass transfer resistances. In the original Krogh cylinder model, a mass transfer resistance shows up but there is no convection in the tissue where convection should matter. In the present study, a two-dimensional flow field is used to show that when a liquid enters the capillary, some leave through the walls into the tissue at the arterial end and then doubles back into the capillary at the venous end. Some flow does not return which is taken to be the flow to the lymphatic system. We can get the measured transcapillary pressure drop of about 2,666 Pa if in addition the compliance of the tube wall is taken into account. Very realistic flow fields have been shown for a model liver and a tumor.     

A comparative study of solar irradiation models on various inclined surfaces for India

This paper presents a statistical approach for the estimation of the diffuse/global irradiation on various inclined surfaces from the measured data of horizontal surface. In fact diffuse solar radiation on an inclined plane consists of two components: sky diffuse radiation and reflected radiation from the ground. For analyzing estimation of the daily tilted sky diffuse component from the daily horizontal diffuse irradiance, we have considered six models Badescu, Circumsolar, Skartveit and Olseth, Hay, Klucher and Liu and Jordan (Isotropic). All these models except Badescu adopted the same methodology for estimating the ground-reflected radiation component, therefore, only sky diffuse component was analyzed at Lucknow (latitude 26.75°, longitude 80.50°), India location. Statistical analysis showed that the Skartveit and Olseth model gives good prediction for the low inclination angle however; Klucher model gave better performance for highly inclined south-facing surfaces. The Root Mean Square Errors (% RMSE) value varies from 3.45% to 24.15% except for Badescu and Circumsolar model which predict worse results. In general, Klucher’s model provides close agreement with the measurements.     

Thermodynamic analysis of hydrogen rich synthetic gas generation from fluidized bed gasification of rice husk

In the present work, the generation of hydrogen rich synthetic gas from fluidized bed steam gasification of rice husk has been studied. An equilibrium model based on equilibrium constant and material balance has been developed to predict the gas compositions. The equilibrium gas compositions are compared with the experimental data of the present group as well as of available literature. The energy and exergy analysis of the process have been carried out by varying steam to biomass ratio (ψ) within the range between 0.1-1.5 and gasification temperature from 600 °C to 900 °C. It is observed that both the energy and exergy efficiencies are maximum at the CBP (carbon boundary point) though the hydrogen production increases beyond the CBP. The HHV (higher heating value) and the external energy input both continuously increase with ψ. However, the hydrogen production initially increases with increase in temperature up to 800 °C and then becomes nearly asymptotic. The HHV decreases rapidly with increase in temperature and energy input increases. Therefore, gasification in lower temperature region is observed to be economical in terms of a trade off between external energy input and HHV of the product gas.     

An efficient contrast-enhancement method using the analog to digital converter

The study presents a hybrid method of contrast enhancement using the analog to digital converter (ADC) for use in high-speed industrial applications. The proposed framework processes the digitized image in efficient steps to generate the low and high offsets of the ADC. These offsets are used to modify the analog image signal by an affine transform, such that the digitization of the transformed signalis the enhanced image. Since the signal transformation is mostly done in the analog domain, the method is efficient, and its implementation is inexpensive. As an example, the enhancement method is used in applications where, given images of varying initial contrast, we can obtain an user-specified contrast for all images. These images are then segmented by a simpler image-processing algorithm. The method is a generalization of existing ADC-based enhancement methods and is compared experimentally to the digital domain techniques. An application of the method is given for the enhancement of laser-etched characters on industrial parts.     

Concentration-induced stress effects in diffusion of vapors through polymer membranes

There are two types of anomalous diffusion of vapors in solid polymers which are held to be due to swelling. If the latter is seen as strain, then there must be an accompanying stress which can affect the nature and magnitude of diffusion. The theories of diffusion in polymers are examined in light of the network theory of Larché and Cahn. Their formalism is used to solve permeation and sorption in polymer membranes to illustrate the general features of the elastic effects, particularly the time-dependent nature of the solubility. That “anomalous” effects will be present is without doubt, considering the concurrent nature of the added elastic effects. However, the present calculations fail to unearth any behavior similar to the case II diffusion. An order of magnitude estimate has been provided which shows that the effects of elasticity are usually significant in rubbery or amorphous glassy polymers where the anomalous effects occur.     

Intersubband transitions at 1.3 and 1.55 μm in a novel coupledInGaAs-AlAsSb double-quantum-well structure

We report the first observation of intersubband absorption at 1.3 μm in a coupled InGaAs-AlAsSb double-quantum-well structure lattice matched to InP substrate. The novel structure exhibits intersubband transitions concurrently at 1.3 and 1.55 μm due to the strong coupling of the intersubband states of the adjacent wells. A transient analysis of optical response in the multilevel conduction subband states for the designed structure indicates ultrafast optical switching behavior with a subpicosecond response     

Heterogeneous Catalytic Oxidative Bromination and Oxidation of Thioethers By Vanadium(IV) Oxido Complex of Benzoylacetone and Effect of Solid Supports

Vanadium(IV) oxido complex of 1-Phenyl-1,3-butanedione [V^IVO(bzac)₂] (1) was prepared, characterized, and heterogenized onto APTMS modified graphene oxide, as well as imidazole modified polystyrene beads. Graphene oxide supported complex GO-APTMS-[V^IVO(bzac)₂] (2) and polymer anchored complex PS-im-[V^IVO(bzac)₂] (3) were used for the oxidative bromination of a number of small organic molecules and oxidation of a series of thioethers. Both 2 and 3 evolve as excellent heterogeneous catalysts. The nature of solid support does not impact substrate conversion (%) during the oxidative bromination of salicylaldehyde, phenol, or styrene, whereas it influences the substrate conversion (%) as well as the product selectivity (%) during the oxidation of thioethers.

Graphic Abstract

     

Simultaneous Quantification of Oil and Protein in Cottonseed by Low-Field Time-Domain Nuclear Magnetic Resonance

Modification of cottonseed quality traits is likely to be achieved through a combination of genetic modification, manipulation of nutrient allocation, and selective breeding. Oil and protein stores account for the majority of mass of cottonseed embryos. A more comprehensive understanding of the relationship between lint quality, lint yield, and embryo reserve accumulation will assist breeders in their efforts to improve seed value. Here we report the development of a rapid, nondestructive, simultaneous method for quantifying oil and protein levels within cottonseed by low-field ¹H time-domain nuclear magnetic resonance (TD-NMR). This approach is suitable for a minimal amount of seed and represents an accurate (oil R ² = 0.998, protein R ² = 0.95), noninvasive alternative to conventional, time-consuming chemical extractions. We demonstrate the value of this approach by surveying seed reserve content, identifying extremes of either protein and/or oil, in two sets of diverse germplasm.     

Wetting kinetics of polymer solutions and force‐based contact angles

The effect of the shear thinning behavior and elasticity of polymer solutions on the dynamic contact angles are investigated. Under dynamic conditions, the contact angle of a liquid on a solid surface changes significantly with the substrate velocity from its equilibrium value. The dynamic contact angles for polyethylene oxide (PEO) solutions of two molecular weights 3 × 10⁵ and 4 × 10⁶ have been measured using a polyethylene terephthalate (PET) plate. The three‐parameter Ellis model to fit the rheological data to obtain shear thinning power n, characteristic shear stress, and the zero‐shear viscosity is used. The theory indicates that dynamic contact angles follow power law in this instance instead of showing Newtonian behavior with zero‐shear viscosity when the shear thinning effects are considered. The elastic effect becomes important at larger polymer concentrations that reduces the dependence on capillary number, that is, reduces n keeping with the experiments. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2533–2541, 2016     

A note on diffuse solar radiation on a tilted surface

We are presenting a note on comparative study of diffuse component of solar radiation on tilted surface with different angle of inclination. The monthly mean daily diffuse radiation have been calculated on inclined surfaces from the data of horizontal surface using the Circumsolar and Isotropic model and the anisotropic model of Klucher and Hay at Lucknow (Latitude 26.75°, Longitude 80.85°), Uttar Pradesh, India. These calculated results are compared with our measured value. The comparison shows that Klucher model who considered the effect of cloudy sky conditions gives comparatively good estimations particularly at low inclination angles.