Attenuation characteristics of a circular chirowaveguide

The attenuation constant of a circular waveguide completely filled with a homogeneous, isotropic and lossless chiral medium is calculated after first solving the wave equation and determining the field components. The waveguide supports only the hybrid modes and the first modes with azimuthal indices of 0 and 1 are studied.<>     

Isolation of ellagic acid from the aqueous extract of the roots of Decalepis hamiltonii: Antioxidant activity and cytoprotective effect

Roots of Decalepis hamiltonii are consumed as pickles and as a beverage and are believed to possess health-promoting properties. Roots of D. hamiltonii exhibit antioxidant properties. We have isolated an antioxidant compound from the aqueous extract of the roots of D. hamiltonii and identified it as ellagic acid (EA), based on NMR and MS. EA exhibited free radical-scavenging activity, inhibited LDL oxidation and showed cytoprotective effect against xenobiotic-induced oxidative stress in Ehrlich Ascites tumor cells. EA is a new addition to the list of antioxidant compounds in the roots of D. hamiltonii.     

A re-entrant line model for software product testing

In today’s competitive environment for software products, quality is an important characteristic. The development of large-scale software products is a complex and expensive process. Testing plays a very important role in ensuring product quality. Improving the software development process leads to improved product quality. We propose a queueing model based on re-entrant lines to depict the process of software modules undergoing testing/debugging, inspections and code reviews, verification and validation, and quality assurance tests before being accepted for use. Using the re-entrant line model for software testing, bounds on test times are obtained by considering the state transitions for a general class of modules and solving a linear programming model. Scheduling of software modules for tests at each process step yields the constraints for the linear program. The methodology presented is applied to the development of a software system and bounds on test times are obtained. These bounds are used to allocate time for the testing phase of the project and to estimate the release times of software.     

Spectrophotometric determination of zinc in foods using N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone: Evaluation of a new analytical reagent

N-ethyl-3-carbazolecarboxaldehyde-3-thiosemicarbazone (ECCT) is proposed as a new sensitive reagent for the extractive spectrophotometric determination of zinc(II). The ECCT forms yellow colored species of zinc(II) at pH range 3.0–5.5 and the complex was extracted into benzene. The Zn(II)–ECCT complex shows maximum absorbance at 420 nm with molar absorptivity and Sandell’s sensitivity being 1.55 × 10⁴ lit mol⁻¹ cm⁻¹ and 4.212 × 10⁻³ μg cm⁻², respectively. The system obeys Beer’s law in the range of 0.4–6.0 mg/l, with an excellent linearity in terms of correlation coefficient value of 0.999. Most of the common metal ions generally found associated with zinc do not interfere. The repeatability of the method was checked by finding relative standard deviation (RSD). The developed method has been successfully employed for the determination of zinc(II) in foods. Various certified reference materials (NIST 1573, NBS 1572 and NIST SRM 8435) have been tested for the determination of zinc for the purpose of validation of the present method.     

Mechanism of C2+ oxygenate synthesis on Rh catalysts

This paper examines the reaction pathways and the nature of active sites for CO hydrogenation in general and C₂₊ oxygenate synthesis over Rh catalysts in particular.     

The x-kernel: a platform for accessing internet resources

x-kernel is an experimental operating system for personal workstations that allows uniform access to resources throughout a nationwide internet: an interconnection of networks similar to the TCP/IP internet. This network is also called the National Research and Education Network (NREN). The x-kernel supports a library of protocols, and it accesses different resources with different protocol combinations. In addition, two user-level systems that give users an integrated and uniform interface to resources have been built on top of the x-kernel. These two systems-a file system and a command interpreter-hide differences among the underlying protocols