Sonosynthesis of Microcellulose from Kenaf Fiber: Optimization of Process Parameters

Green composites using cellulose fibers as a reinforcement material provide a sustainable and renewable alternative to petroleum-based polymers. However, controlling the usage of chemicals and processing parameters to extract the cellulose could be sometimes difficult. Therefore, this study aims to optimize the conditions for extracting the microcellulose from kenaf fibers using central composite design (CCD), a statistical tool in design of experiments. Three factors and three levels were chosen for carrying out the analysis. The design was based on sodium hydroxide (NaOH) dosage, Sodium Chlorite (NaClO₂) dosage and sonication time as independent variables, while dependent variables were the fiber size and degradation point. Later, size responses were fitted using quadratic polynomial model and degradation responses using 2-factor interaction model (2FI). The R² values of 0.89 and 0.83 were obtained for the quadratic and the 2FI model, respectively. Further, surface morphology, thermal analysis, Fourier transform infrared (FTIR) spectroscopy and X-Ray diffraction (XRD) were also used for design validation. Optimal parameters for microcellulose extraction were found to be 0.15 g of NaOH at first stage, 4.6 mL of NaClO₂ at second stage, and 10 min of sonication during third stage.     

Middleware Architecture for Next Generation Heterogeneous Networks

In this paper we present a framework, called Futon, which provides a platform to integrate heterogeneous radio access networks. Futon is a hybrid fibre-radio network that replaces legacy base stations with simple remote antenna units, which are connected to a central unit. As a part of the Futon framework, a generic middleware architecture is discussed in detail, which provides interoperability, cooperative management and service provisioning to both underlying radio access networks (RANs) and IP layer for a heterogeneous network scenario. One of the middleware??s functionality is to provide vertical handover between heterogeneous IP-based radio access technologies and to ensure seamless mobility and service continuity, which is implemented on top of an IPv4/IPv6 Mobile IP (MIP) core. In this paper, the Futon framework and a generic middleware architecture as a part of Futon framework for heterogeneous RANs is discussed. The main modules of the middleware, namely common radio resource management (CRRM), media independent handover, Service/Connection Manager and link selection are explained in detail. Radio over fibre (RoF) Manager is an important part of Central unit, which does performance, fault and security management of network elements. RoF manager helps middleware during handoff, by providing the status of fibre optic links. The implementation of Security management module as a part of RoF manager, and results of authentication with AAA protocol are explained. The CRRM as part of middleware is simulated and the results of experimental evaluation are presented.     

Random Mobility and Heterogeneity-Aware Hybrid Synchronization for Wireless Sensor Network

Random mobility of a node in wireless sensor networks (WSNs) causes the frequent changes in the network dynamics with increased cost in terms of energy and bandwidth. During data collections and transmission, they need the additional efforts to synchronize and schedule the activities of nodes. A key challenge is to maintain the global clock scale for synchronization of nodes at different levels to minimize the energy consumption and clock skew. It is also difficult to schedule the activities for effective utilization of slots allocated for aggregated data transmission. The paper proposes the Random Mobility and Heterogeneity-aware Hybrid Synchronization Algorithm (MHS) for WSN. The proposed algorithm uses the cluster-tree for efficient synchronization of CH and nodes in the cluster and network, level-by-level. The network consists of three nodes with random mobility and are heterogeneous regarding energy with static sink. All the nodes and CH are synchronized with the notion of the global timescale provided by the sink as a root node. With the random mobility of the node, the network structure frequently changes causing an increase in energy consumption. To mitigate this problem, MHS aggregate data with the notion of a global timescale throughout the network. Also, the hierarchical structure along with pair-wise synchronization reduces the clock skews hence energy consumption. In the second phase of MHS, the aggregated data packets are passed through the scheduled and synchronized slots using TDMA as basic MAC layer protocol to reduce the collision of packets. The results are extended by using the hybrid approach of scheduling and synchronization algorithm on the base protocol. The comparative results show that MHS is energy and bandwidth efficient, with increased throughput and reduced delay as compared with state-of-the-art solutions.     

Enhancing the Performance of Video Streaming in Wireless Mesh Networks

Multihop wireless mesh networks (WMNs) provide ubiquitous wireless access in a large area with less dependence on wired networks. However, some emerging applications with high bandwidth requirement and delay and loss constraints, such as video streaming, suffer poor performance in WMNs, since high compression rates and/or high packet loss rates deteriorate the video quality. In this paper, we propose a novel mechanism composed of (1) a network route selection scheme which provides paths for multiple video streams with the least interference, called Minimum Interference Route Selection (MIROSE) and (2) an optimization algorithm that determines the compression rates depending on the network condition, called Network State Dependent Video Compression Rate (NSDVCR) algorithm. Simulation results of the proposed mechanisms show the significant improvement of the video quality measured with a popular metric, Peak-Signal-to-Noise Ratio (PSNR), compared with standard routing and default compression rates.     

A New Technique for Forecasting Surface Wind Field From Scatterometer Observations: A Case Study for the Arabian Sea

The possibility of predicting ocean-surface wind field a few days ahead from satellite scatterometer observations in the Arabian Sea has been explored in this paper. The prediction technique is based on a combination of empirical orthogonal function (EOF) analysis and genetic algorithm (GA). The space-time distributed satellite data (zonal or meridional wind field) have been decomposed into a set of spatial eigenmodes ranked by their temporal variance. The associated temporal amplitude functions have been used by the GA for carrying out forecasts with lead times varying from one to five days. The GA finds the analytical equations that best describe the behavior of the different temporal amplitude functions in the EOF decomposition. Later, the predicted wind field has been generated as a linear combination of the dominant spatial modes weighted by the corresponding predicted amplitudes. The technique has been tested using independent validation data sets. It has been further tested by comparing the forecast fields with buoy data. The performance of GA is comparable to that of persistence forecast for the first two days of forecast, while it is better than that of persistence for three- to five-day-ahead forecasts     

Implementation of AES Key Schedule Using Look-Ahead Technique

The commencement of decryption process of Advanced Encryption Standard (AES) algorithm is dependent on availability of the last round key. In this paper, we propose a look-ahead technique for increasing the speed of implementation of AES key schedule using which the last round key can be made available fast. The other round keys can also be computed in a parallel path using the proposed technique. Applications such as key search engines need to be agile to key changes for decrypting given encrypted messages using all the keys in the available key space so that fast decryption is possible. The FPGA implementation results using Xilinx XC5VLX85 are also provided.     

Controlled drug release characteristics and enhanced antibacterial effect of graphene nanosheets containing gentamicin sulfate

A novel methanol derived graphene (MDG) and gentamicin sulfate nanohybrid was prepared, and the loading and release behaviour of gentamicin on MDG is investigated. An efficient drug loading of 2.57 mg mg(-1) was obtained at pH 7. By applying release kinetic models, the mechanism of release of the drug from the MDG matrix was found to be following the Korsmeyer-Peppas model. However, the diffusional release exponent (n) value lies below 0.5 demonstrating that the mechanism controlling the drug release is the Fickian diffusion.     

Validation of arrayed imaging reflectometry biosensor response for protein-antibody interactions: cross-correlation of theory, experiment, and complementary techniques

One of the critical steps in the development of an analytical technique is to confirm that its experimental response correlates with predictions derived from the theoretical framework on which it is based. This validates the technique quantitatively and, in the case of a biosensor, facilitates a correlation of the sensor's output signal to the concentration of the analyte being tested. Herein we report studies demonstrating that the quantitative response of arrayed imaging reflectometry (AIR), a highly sensitive label-free biosensing method, is a predictable function of the probe and analyte properties. We first incorporated a standard one-site Langmuir binding model describing probe-analyte interactions at the surface into the theoretical model for thickness-dependent reflectance in AIR. This established a hypothetical correlation between the analyte concentration and the AIR response. Spectroscopic ellipsometry, surface plasmon resonance, and AIR were then used to validate this model for two biomedically important proteins, fibroblast growth factor-2 and vascular endothelial growth factor. While our studies demonstrated that the 1:1 one-site Langmuir model accurately described the observed response of macrospot AIR arrays, either a two-site Langmuir model or a Sips isotherm better described the behavior of AIR microarrays. These studies confirmed the quantitative performance of AIR across a range of probe-analyte affinities. Furthermore, the methodology developed here can be extended to other label-free biosensing platforms, thus facilitating a more accurate and quantitative interpretation of the sensor response.     

Analysis of cellular metabolism of hybridoma cells at distinct physiological states

Hybridoma cells were cultivated in a chemically defined medium in continuous cultures. These cultures reached different steady states marked by distinctive cell metabolism depending on the culture conditions leading to the steady state. Those steady states with different metabolism are characterized by different stoichiometric ratios of lactate production to glucose consumption (deltaL/deltaG). The specific consumption rates of glucose, glutamine and other amino acids are reduced when DeltaL DeltaG reduces. Those steady states do not have a few discrete values of deltaL/deltaGs , rather they span from a high deltaL/deltaG state (> 1.0) to an intermediate state (0.1 < or = deltaL/deltaG < or = 1.0), and reduces even further at a low deltaL/deltaG state (< 0.1). Metabolic flux analysis was performed to compare energy metabolism of cells in cultures representing these three distinct metabolic states. The material balance on carbon and nitrogen was facilitated by the use of chemically defined medium. The formation of biomass was systematically estimated. It was revealed that all glycolysis and TCA cycle fluxes are reduced as deltaL/deltaG decreases. At the low deltaL/deltaG state, a reduction in amino acid specific consumption rate is accompanied by a reduction in all the fluxes around pyruvate. The analysis also shows that the outflux from the TCA cycle to form pyruvate, which contributes to lactate formation, is possibly linked to the higher consumption rate of amino acids at the high deltaL/deltaG state. Taken together the results suggest the amino acid metabolism plays an important role in reducing lactate production in mammalian cell culture.     

Capability-Based Access Control with ECC Key Management for the M2M Local Cloud Platform

Wireless Personal Communications - One of the critical requirement in managing security of any computing system is access control, which includes protection and access management to the available...