Properties of Natural Fibers Separated from Chromolaena odorata and Mikania micrantha

This paper reports the possibility of separating natural fibers from two invasive alien plants Chromolaena odorata and Mikania micrantha. These two are considered as high-risk species on the basis their invasiveness and being a menace to the natural biodiversity of Kerala, India. Water retting and alkali extraction methods were used for the separation of stem fibers. Fibers obtained showed similar properties to currently used common fibers. Based on morphometric measurements and derived values, such as slenderness ratio, flexibility ratio, and Runkel ratio, these fibers are expected to be suitable for industrial purposes.     

Efficient cage structured polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol) membranes: Thermal degradation and mechanical stability in hydrated condition

In this work, the thermal degradation of functionalized cage structured polyhedral oligomeric silsesquioxane (POSS) incorporated poly(vinyl alcohol) (PVA) and poly(vinyl alcohol)-poly (ethylene oxide) (PEO) blend membranes were discussed. PVA-PEO/POSS and cross-linked PVA/POSS systems exhibited excellent improvement in thermal stability at lower loading of POSS as compared to pure PVA and uncross-linked PVA/POSS system. Uncross-linked PVA and PVA/POSS systems exhibited mainly two degradation steps. However, cross-linked PVA/POSS systems showed more degradation steps due to the formation of 3-dimentional network structure in the polymer. The mechanical stability of PVA/POSS and PVA-PEO/POSS systems at hydrated state were analyzed and observed a remarkable stability even in the wet condition.     

A time/structure based software reliability model

The past 20 years have seen the formulation of numerous analytical software reliability models for estimating the reliability growth of a software product. The predictions obtained by applying these models tend to be optimistic due to the inaccuracies in the operational profile, and saturation effect of testing. Incorporating knowledge gained about some structural attribute of the code, such as test coverage, into the time-domain models can help alleviate this optimistic trend. In this paper we present an enhanced non-homogeneous Poisson process (ENHPP) model which incorporates explicitly the time-varying test-coverage function in its analytical formulation, and provides for defective fault detection and test coverage during the testing and operational phases. It also allows for a time varying fault detection rate. The ENHPP model offers a unifying framework for all the previously reported finite failure NHPP models via test coverage. We also propose the log-logistic coverage function which can capture an increasing/decreasing failure detection rate per fault, which cannot be accounted for by the previously reported finite failure NHPP models. We present a methodology based on the ENHPP model for reliability prediction earlier in the testing phase. Expressions for predictions in the operational phase of the software, software availability, and optimal software release times subject to various constraints such as cost, reliability, and availability are developed based on the ENHPP model. We also validate the ENHPP model based on four different coverage functions using five failure data sets. This revised version was published online in June 2006 with corrections to the Cover Date.     

Free volume defects and transport properties of mechanically stable polyhedral oligomeric silsesquioxane embedded poly(vinyl alcohol)‐poly(ethylene oxide) blend membranes

Polymer membrane based gas transport and pervaporation processes are fast growing areas in separation technology and have received wide attention as areas of ‘clean technology’. Mechanically stable novel polyhedral oligomeric silsesquioxane (POSS) embedded poly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) blend membranes were prepared by solution blending followed by casting. The addition of carboxymethyl cellulose enhanced the interfacial activities of the PVA and PEO blends. The peripheral organic substituent on POSS plays a key role in achieving compatibility with polymers whereas the rigid Si–O–Si core of POSS imparts high mechanical strength. Compared to PVA membrane, poly(ethylene glycol) and octa(tetramethylammonium) functionalized POSS embedded PVA/PEO membranes exhibit 680% and 580% enhancement in Young's modulus as well as 130% and 140% improvement in tensile strength respectively. The Einstein, Kerner and Frankel–Acrivos models were applied to compare the experimental and theoretical Young's modulus of PVA‐PEO/POSS membranes. The presence of an ethylene oxide tail on POSS as well as PEO in the blend membrane enhances the CO₂ affinity of the membrane. The presence of a hydrophilic functional group on the POSS improves the hydrophilicity of the membrane and produces more binding sites for water molecules in the membrane during the pervaporation separation of a tetrahydrofuran–water azeotropic mixture. The transport properties of the membrane are further elucidated by means of free volume defect analysis carried out by positron annihilation lifetime spectroscopy and coincidence Doppler broadening spectroscopy. © 2019 Society of Chemical Industry     

A Review on the Adsorption Studies of Tetracycline onto Various Types of Adsorbents

Over the past few decades, the usage of antibiotics is growing on a rapid phase. The continuous use in the treatment against several bacterial infections paves a way to increased resistant strains. Environmental pollution created by antibiotics is considered as a serious problem though no toxic reports were known until now. The pharmaceutical compounds present in the environment are known as “Emerging Pollutants.” Among antibiotics, tetracycline (TET) class of drugs were known to exist for several years. Within 3–4 years of the discovery of the first class of TET, the resistant strains were also identified. TET usage is not only limited for human therapy but also greatly used in veterinary and agricultural purposes. These compounds have been detected in the environment, especially in aquatic farms, groundwater, surface water, etc., thus, it becomes vital to take some measures in removing these compounds from the ecosystem to some extent. Many degradation methodologies and mechanisms were applied to remove TET but were highly limited to synthetic effluents. Adsorption is a common practice at the industrial level, especially in effluent treatment processes. In this study, removal of TET through adsorption using various adsorbents was reviewed extensively.     

Effects of Epithermal Neutron Irradiation on the Characteristics of the Porous Silicon

Silicon - Porous silicon (PSi) samples were irradiated in the epithermal neutron spectrum for 17 h and drastic changes were observed in its electrical, optical and morphological...     

Emerging Trends in Nano Structured Silicon Detectors for Neutron Spectroscopy

Silicon - Neutron detectors are extensively used in numerous applications such as, in nuclear fuels plants, high energy accelerators, space explorations, imaging etc. Among the commercially...     

Using statistical data for reliable mobile communications

We examine the extent to which statistical mobility information can increase the reliability of the service experienced by users in mobile networks. Interrupted or dropped calls are an aspect of reliability that stems from the mobility of users. An existing user can move to a cell where there are no resources available to support their call. A natural solution is the reservation of resources in multiple cells that the user is likely to move to. This scheme is called selective reservations and it relies on predicting the next move of the user. Recently, there has been some work on estimating the movement probabilities (also known as the mobility profile) of the user. In this paper, we quantify the usefulness of the mobility profile to improve the reliability of the service perceived by the mobile users. We identify two parameters which characterize the profile: Accuracy and Focus. Accuracy expresses the probability that the host will move as we expect it to. Focus describes how well we can identify patterns in the movement of the users. In our simulations, we examine the effect of the quality of the predictions on the performance of the system. We show that Accuracy and Focus have great impact on the performance of selective reservations. We also show how flexibility in hand‐offs can help in decreasing the dropping probability, and how this can be facilitated by letting the users make a second try at moving in case it fails the first time. Copyright © 2001 John Wiley & Sons, Ltd.