Influence of Inlet Premixing on Two-Phase Flow Patterns in a Horizontal Minichannel

Experimental investigations are reported for air–water two-phase flow through a 2.1-mm horizontal circular minichannel. Influence of inlet premixing on two-phase flow is established by constructing various T-junction geometries with cross-flow arrangement of air and water. Six different flow patterns are observed and flow pattern maps are developed. The developed flow pattern maps are then compared for different inlet designs. It is observed that the degree of premixing of the two fluids has significant effect on flow patterns, particularly for surface-tension-dominated regime. The results obtained from these experiments can provide guidelines for selection, design, and control of wide-ranging microfluidic applications. The flow pattern map established in the present study may facilitate prediction of flow regimes in pulsating heat pipes based on the inlet flow rates of the gas and liquid.     

Accurate size evaluation of cylindrical components

The objective of this paper is to develop a methodology to calculate the size of a cylindrical profile accurately per American National Standards Institute (ANSI) standards. The ANSI Y14.5.1M–1994 standard defines the size of a cylinder as the size of the largest ball rolling on a spine such that all points on the surface of the cylinder are external to it or the size of the smallest ball rolling on a spine such that all points on the surface of the cylinder are internal to it. Current methods of size evaluation reduce the complexity of the spine and model it as a straight line. In this paper, a methodology is presented to evaluate the control points of the spine modeled as an open uniform B-spline curve of a prespecified degree based on points collected on the surface of the cylinder. This provides a quantitative measure of the size of the cylinder in accordance with ANSI standards. The formulations to evaluate the maximum inscribing spine and the minimum circumscribing spine are presented as multilevel optimization problems. The outer level optimization is used to identify the optimal set of control points for the spline representing the path of the rolling ball. The inner level optimization is used to find the nearest point on the spline corresponding to every point in the dataset. The optimization formulation presented in this paper has been used to calculate the true size of cylinders for several published, simulated, and real datasets. These results are then compared to traditional estimates for size of a cylinder. The results indicate that the method presented for calculating the size of a cylinder conforms better to the ANSI standards as compared to other methods, such as the maximum inscribed, minimum circumscribed, and least squares cylinders, which have been traditionally used as indicators of size of a cylinder [1]. Further analysis is presented to observe the effect of sample size on the results of the algorithm. It is observed that with an increase in the sample size, the difference between the results of the presented algorithm and the traditional methods increases with the presented method providing more accurate estimates.     

Synthesis and characterisation of starch/agar nanocomposite films for food packaging application

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8–15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of Pseudomonas aeruginosa and Staphylococcus aureus in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram‐negative P. aeruginosa. Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.Inspec keywords: casting, microorganisms, scanning electron microscopy, nanoparticles, food preservation, solubility, thermal analysis, zinc compounds, food processing industry, food products, thermal stability, permeability, antibacterial activity, food packaging, contaminationOther keywords: water vapour permeability, food packaging, solution casting method, structural properties, physical properties, antimicrobial properties, water solubility, agar nanocomposite film, starch nanocomposite film, Pseudomonas aeruginosa, Staphylococcus aureus, bacterial contamination prevention, spoilage prevention, scanning electron microscopic analysis, thermogravimetric analysis, temperature 150.0 degC, Ag, ZnO     

Effects of interaction richness on consumer attitudes and behavioral intentions in e-commerce: some experimental results

A variety of information and communication media have been employed to support the interaction of consumers with products and sales representatives in electronic-commerce (EC). But, the question of what impact those media have on consumers in EC has not been sufficiently addressed in the literature. The objective of this study is to investigate the effect of the richness of consumers’ interaction with products and with sales representatives on changes in their attitude towards and their intention to use business-to-consumer (B2C) EC. Controlled lab experiments were conducted using two types of products and multiple levels of interaction richness. The results show that interaction richness has positive impact on consumers’ attitude towards B2C EC. Additionally, the study finds that the impact is stronger in the case of purchasing a high-complexity product than a low-complexity product, and that consumers’ attitude change is positively related with their intention to use B2C EC. Differential effects on two facets of attitude, ease of use in accomplishing the tasks and usefulness were observed leading to interesting implications and future research directions.     

Assessment of blood supply in superficial tissue by polarization-gated elastic light-scattering spectroscopy

We report the feasibility of monitoring both hemoglobin oxygen saturation and hemoglobin concentration in the superficial layer of tissue using polarization-gated elastic light-scattering spectroscopy. We detail our analysis technique, the experimental validation of our analysis, and the detection of an early increase in blood supply to the superficial layer of colon tissue in human patients with colonic adenomas as well as in an animal model of colon carcinogenesis. To the best of our knowledge, this study represents the first evidence that polarization gating can be used as a spectroscopic tool to quantify hemoglobin concentration as well as oxygen saturation in the uppermost tissue layer.