Removal of Pb(II) ions from aqueous solution by adsorption using bael leaves (Aegle marmelos)

Biosorption of Pb(II) on bael leaves (Aegle marmelos) was investigated for the removal of Pb(II) from aqueous solution using different doses of adsorbent, initial pH, and contact time. The maximum Pb loading capacity of the bael leaves was 104 mg g^?1 at 50 mg L^?1 initial Pb(II) concentration at pH 5.1. SEM and FT-IR studies indicated that the adsorption of Pb(II) occurs inside the wall of the hollow tubes present in the bael leaves and carboxylic acid, thioester and sulphonamide groups are involved in the process. The sorption process was best described by pseudo second order kinetics. Among Freundlich and Langmuir isotherms, the latter had a better fit with the experimental data. The activation energy E_a confirmed that the nature of adsorption was physisorption. Bael leaves can selectively remove Pb(II) in the presence of other metal ions. This was demonstrated by removing Pb from the effluent of exhausted batteries.     

Secure Data Transfer Using Multi Layer Security Protocol with Energy Power Consumption AODV in Wireless Sensor Networks

Wireless Personal Communications - Nonnegative Matrix Factorization (NMF) has been becoming an important method for feature dimension reduction in recent years since it can represent data with...     

Dry etching of GaN using chemically assisted Ion beam etching with HCI and H2/Cl2

The dry etching characteristics of GaN were investigated using chemically assisted ion beam etching (CAIBE) with HCI and H₂/Cl₂ gas. Etch rates using CAIBE/HC1 were investigated as a function of Ar ion beam energy and substrate temperature. These results were compared to CAIBE/C1₂. Etch rates were also investigated for CAIBE/H₂/Cl₂ for various ratios of H₂:C1₂. Highly anisotropic submicron lines are demonstrated using CAIBE/HC1. Auger electron spectroscopy was used to investigate surface stoichiometric changes of samples etched with CAIBE/HC1, CAIBE/H₂/Cl₂,, and CAIBE/C1₂. The diffusion of deuterium into GaN during etching was also investigated using secondary ion mass spectrometry.     

Implantable pacemakers

Advances in cardiac pacing have greatly reduced the size of pacemakers, while improving their longevity and reliability, expanding their clinical applications and increasing their sophistication in terms of programming and automatic features. Significant reductions in the size of pacing systems have been mainly due to improvements in power sources, increased circuit integration, hybrid packaging, and the development of smaller leads and lead connectors. The use of sophisticated microprocessors has transformed some pacemakers into implantable computers. The incorporation of memory is enabling modern pacing devices to become more like Holter monitors, able to store significant amounts of intracardiac data. A trend toward the use of sensor technology has enabled pacemakers to provide rate response, taking the place of a damaged sinus node     

Design and Development of Flexible PDMS Antenna for UWB-WBAN Applications

Wireless Personal Communications - This paper presents the design and development of a flexible Ultra Wide Band (UWB) antenna using polydimethylsiloxane as a substrate. Copper foil having a...     

Dynamic Flow Model for Borrowing Channel Ordering Assignment Scheme in Cellular Mobile Systems

A mathematical model that predicts the dynamic flows in cellularmobile networks that allocate channels using the Borrowing ChannelOrdering Assignment (BCO) scheme is described in this paper. Two types ofhandoff procedures – the prioritized and non-prioritized schemes –will be considered in the model. Discrete event simulations wereperformed and the results were found to be comparable to the resultsobtained using the mathematical model. Application to comparative studyof the dynamic behaviours of the BCO, the simple borrowing channel assignment(BCA) and the Fixed Channel Assignment (FCA) schemes is also presented.     

The applications-assured infrastructure

Accurate knowledge of how applications are performing across a corporate enterprise infrastructure is a key factor in developing strategy for enterprise IT optimisation aligned to business drivers. BT’s applications-assured infrastructure proposition provides the ability for customers to understand where their application bottle-necks are, fix problems, optimise performance and provide long-term enterprise IT health monitoring. This is a big step towards the goal of supporting guaranteed end-to-end applications performance — the next level of quality-of-service-based product requirements.     

Analysis of a new multiband multiport circuit for phase detection applications

A new multiband multiport circuit is presented in this letter. This circuit, designed for microwave phase detection applications, can be used in multiband direct conversion front-ends, phased-array antenna drivers or other microwaves amplitude or phase measurements. A complex vector, named /spl Gamma/, based on multiport output voltages, is introduced for direct RF phase measurements. An excellent match of simulation and measurement results is obtained in all frequency bands.     

Characterizing relative intensity noise in InGaAsP-InP triangular ring lasers

This paper discusses relative intensity noise (RIN) characterization of triangular ring lasers, fabricated through a self-aligned dry etching process in InGaAsP-InP. Unusual low frequency noise enhancement was observed in each of the output beams, that is strongly dependent on the mirror backscattering strength. We explain the physical origin of the unusual RIN results as a partition noise effect between the two output beams of the ring laser, which can be best interpreted as superposition of two incoherent spatially bidirectional modes, generated by incoherent spontaneous emission photons traveling in clockwise and counterclockwise directions. This effect is unique to the ring laser geometry, and reported here for the first time. General noise predictions of our analysis are consistent with experimental measurements. This partition noise enhancement is expected to be present in the entire class of bidirectional semiconductor ring lasers, affecting the noise performance of not only the triangular ring laser, but also circular and square geometries, and possibly microdisk type lasers, in integrated photonic circuit applications.     

Particle conservation in the hot‐carrier solar cell

In conventional p–n junction solar cells, carrier multiplication by impact ionisation, is negligible, owing to the low temperature of the electron–hole pairs. This leads to particle conservation between the net number of absorbed photons and the number of electron–hole pairs withdrawn from the cell. In hot‐carrier solar cells, in which electrons are at a high temperature by assuming suppression of electron–phonon scattering, such particle conservation leads to peculiar results. Numerical calculations show that entire current–voltage characteristics with meaningful values of temperature and chemical potential do not exist. If the energy at which electron–hole pairs are extracted is smaller than the average energy of absorbed photons, the temperature of the electrons and holes becomes much larger than the tem perature of the sun. When the extraction energy is larger than the average energy of the absorbed photons, an entire current–voltage curve cannot always be obtained. It follows that impact ionisation and Auger recombination cannot be neglected when the thermal energy of the electron–hole pairs is comparable to the bandgap of the absorber. Accounting for these processes results in current–voltage characteristics that are well behaved. Copyright © 2005 John Wiley & Sons, Ltd.