Pervaporation separation of water‐isopropanol mixtures using polymeric membranes: Modeling and simulation aspects

Pervaporation technique was used to separate water + isopropanol azeotropic mixtures at 30°C using pure sodium alginate, pure poly(vinyl alcohol), and blend membranes of sodium alginate containing 10 and 20 mass % of poly(vinyl alcohol). The membrane performance was studied by calculating flux, selectivity, pervaporation separation index, and enrichment factor. Pure sodium alginate membrane gave the highest pervaporation separation index for all compositions of water. Pervaporation experiments were carried out for 10 mass % containing water + isopropanol mixture at 30, 40, and 50°C. The Arrhenius activation parameters were computed. The PV results have been analyzed by considering complete mixing and plug flow models. Design parameters, like membrane area, permeate concentrations, flux, stage cut, separation selectivity, etc., have been calculated for different feed compositions of water in the mixture. Results are explained in terms of sorption‐diffusion principles. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1143–1153, 2005     

Physico‐mechanical,dynamic mechanical,and swelling properties of sodium chloride filled chlorobutyl vulcanizates

The effect of addition of rigid, nonreinforcing, and noninteracting filler viz. finely ground NaCl in chlorobutyl vulcanizates on properties such as physicomechanical, dynamic mechanical, and swelling has been studied. The nonreinforcing effect of NaCl in the system was studied by Russel and Cunnenn analysis and Kraus plots. Mechanical measurements of stress and strain at the break of filled and unfilled samples showed no appreciable change in the mechanical behavior of the system. The dynamic mechanical analysis showed that there is no change at all in the glass transition temperature with addition of NaCl filler. The damping properties showed an increase with increase in filler loading because of the filler–filler friction. The swelling behavior of NaCl‐filled CIIR was studied for a period of 60 days in four different solvents of varying chemical energy potential viz. water, chloroform, acetone, and tetrahydrofuran (THF). The degree of swelling was found to increase continuously with time in water, which is a good solvent for the filler, and in THF, which is a good solvent for the polymer matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 707–714, 2006     

Effect of carbon blacks on relaxation phenomenon of chlorobutyl vulcanizates

The effect of the types of carbon black on the physicomechanical, dynamic mechanical, and dielectric relaxation spectra in chlorobutyl vulcanizates was studied. The primary relaxation (α transition, the glass transition) was studied by dynamic mechanical analysis as a function of temperature (?60 to +100°C) and by positron annihilation lifetime spectroscopy (?70 to +100°C). Irrespective of the type of carbon black that was used, all composites showed glass‐transition temperatures in the range of ?29 to ?33°C, which was explained on the basis of the relaxation dynamics of polyisobutylene chains in the vicinity of the fillers. The secondary relaxation (α* or β relaxation) was studied using dielectric relaxation spectra in the frequency range of 100–10⁶ Hz. The nonlinear strain dependent dynamical parameters (Payne effect) were also evaluated at dynamic strain amplitudes of 0.07–5%. The nonlinearity in the tan δ and storage modulus was explained by the concept of filler–polymer interactions and the interaggregate attraction (filler networking). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1809–1820, 2006     

Enhanced field emission characteristics of nitrogen-doped carbon nanotube films grown by microwave plasma enhanced chemical vapor deposition process

Nitrogen-doped carbon nanotube (CNT) films have been synthesized by simple microwave plasma enhanced chemical vapor deposition technique. The morphology and structures were investigated by scanning electron microscopy and high resolution transmission electron microscopy. Morphology of the films was found to be greatly affected by the nature of the substrates. Vertically aligned CNTs were observed on mirror polished Si substrates. On the other hand, randomly oriented flower like morphology of CNTs was found on mechanically polished ones. All the CNTs were found to have bamboo structure with very sharp tips. These films showed very good field emission characteristics with threshold field in the range of 2.65-3.55 V/μm. CNT film with flower like morphology showed lower threshold field as compared to vertically aligned structures. Open graphite edges on the side surface of the bamboo-shaped CNT are suggested to enhance the field emission characteristics which may act as additional emission sites.     

Hierarchical Aggregation and Intelligent Monitoring and Control in Fault-Tolerant Wireless Sensor Networks

The primary idea behind deploying sensor networks is to utilize the distributed sensing capability provided by tiny, low powered, and low cost devices. Multiple sensing devices can be used cooperatively and collaboratively to capture events or monitor space more effectively than a single sensing device. The realm of applications envisioned for sensor networks is diverse including military, aerospace, industrial, commercial, environmental, and health monitoring. Typical examples include: traffic monitoring of vehicles, cross-border infiltration detection and assessment, military reconnaissance and surveillance, target tracking, habitat monitoring, and structure monitoring, to name a few. Most of the applications envisioned with sensor networks demand highly reliable, accurate, and fault-tolerant data acquisition process. In this paper, we focus on innovative approaches to deal with multivariable, multispace problem domains (data integrity, energy-efficiency, and fault-tolerant framework) in wireless sensor networks and present novel ideas that have practical implementation in developing power-aware software components for designing robust networks of sensing devices.     

Tandem dialyzers with dual monitors to meet Kt/V targets

Purpose:  This study evaluated improvements in dialyzer reuse parameters and clinical outcomes associated with a CQI project in a hospital‐based dialysis center in which high flux polysulfone dialyzers were replaced with high flux Polyflux® dialyzers (GAMBRO® Renal Products). Methods:  Dialyzers were reprocessed using a Renatron® II Dialyzer Reprocessing System in conjunction with Renalin® sterilant (Minntech Corp.). Renalog® RM software was used to track dialyzer reprocessing rates and failures. Reasons for dialyzer failure included inadequate dialyzer volume; excess pressure; appearance; clotting during use; and maximum number of uses reached. The average number of dialyzer reuses with polysulfone dialyzers between January and June 2002 were compared to that achieved with Polyflux® dialyzers for the same periods in 2003 and 2004. Analysis periods were separated to avoid the impact of dialyzer transition on clinical parameters. Achievement of URR goals during these same periods was likewise compared. Results:  Transition from polysulfone to Polyflux® dialyzers was associated with a >40% increase in average number of reuses between 2002 and 2003 and a >63% increase comparing the 2002 and 2004 periods. During the 2002 analysis period with polysulfone dialyzers the target URR of 65% was achieved in approximately 75% of hemodialysis patients; this increased to nearly 95% with Polyflux® dialyzers in both the 2003 and 2004 periods, despite more reprocessing of these dialyzers. Conclusions:  These results demonstrate an improvement in both reuse efficiency and clinical outcomes associated with Polyflux dialyzers. Identifying clinical products through CQI studies that provide an economic and clinical advantage plays an important role in the success of hospital‐based hemodialysis.     

Robust output feedback regulation of minimum-phase nonlinear systems using conditional integrators

This paper is on the design of robust output feedback integral control for minimum-phase nonlinear systems with a well-defined relative degree. Previous work has shown how to design such controllers to achieve asymptotic regulation by a two-step process. First, robust control is designed to bring the trajectories to a small neighborhood of an equilibrium point. Within this neighborhood, the control then acts as a high-gain feedback that stabilizes the equilibrium point.The asymptotic regulation achieved by integral action happens at the expense of degrading the transient performance. In this paper, we present an approach to improve the transient performance. The control design is a continuous sliding mode control with integral action. However, the integrator is introduced in such a way that it provides integral action only “conditionally”, effectively eliminating the performance degradation. There are two main results in the paper: the first is asymptotic regulation and the second confirms the transient performance improvement by showing that the output feedback continuous sliding-mode control with integral action can be tuned to recover the performance of a state feedback ideal sliding mode control without integral action.     

Angular and polarization response of vegetation,bare soil and water from ADEOS POLDER data over India

In this letter, the angular variations of total and polarized reflectances of vegetation, bare soil and water with respect to different Sun-target-view angles, obtained from ADEOS (Advanced Earth Observation Satellite) POLDER (Polarisation and Directionality of Earth Reflectances) measurements acquired over the Indian sub-continent during 7 November 1996, are analysed at three wavelengths, namely, 443, 670 and 865 nm. The POLDER measured reflectances are approximately corrected for molecular and aerosol effects due to path radiance assuming a single layer, horizontally homogeneous atmosphere. The variation of total and polarized reflectances of three targets as a function of view zenith and relative azimuth angles are presented. The corrected target polarized reflectances show a monotonic decrease with relative azimuth and view zenith angles. A semi-empirical model was fitted to the corrected total reflectances for the three targets at three wavelengths. Statistical analysis of regression coefficients show that the coefficient corresponding to normalized reflectance, k₀, is physically significant.     

Petri net models for the semi-automatic construction of large scale biological networks

For the implementation of the virtual cell, the fundamental question is how to model and simulate complex biological networks. During the last 15 years, Petri nets have attracted more and more attention to help to solve this key problem. Regarding the published papers, it seems clear that hybrid functional Petri nets are the adequate method to model complex biological networks. Today, a Petri net model of biological networks is built manually by drawing places, transitions and arcs with mouse events. Therefore, based on relevant molecular database and information systems biological data integration is an essential step in constructing biological networks. In this paper, we will motivate the application of Petri nets for modeling and simulation of biological networks. Furthermore, we will present a type of access to relevant metabolic databases such as KEGG, BRENDA, etc. Based on this integration process, the system supports semi-automatic generation of the correlated hybrid Petri net model. A case study of the cardio-disease related gene-regulated biological network is also presented. MoVisPP is available at .     

Optical mapping of crack tip deformations using the methods of transmission and reflection coherent gradient sensing: a study of crack tip K-dominance

A new full field optical technique-Coherent Gradient Sensing (CGS)-is developed and used to study crack tip deformations in transparent as well as opaque solids. A first order diffraction analysis is provided for the technique and its feasibility is demonstrated both in transmission and reflection modes. Preliminary results from the dynamic crack growth experiment clearly demonstrate the capability of CGS to be an effective experimental alternative to other optical methods used in dynamic fracture studies. Notably, it is a full field technique which works with optically isotropic materials.The static fringe patterns obtained from the experiments are analyzed in regions outside the 3-D zone. For geometries where the region outside the 3-D zone is K-dominant, the fringes provide an accurate value of 2-D stress intensity factor. For geometries where the region outside the 3-D zone is not K-dominant, Williams' expansion is used in conjunction with a least squares procedure to obtain the stress intensity factors.