The effect of biological studies of polyester composites filled carbon black and activated carbon from bamboo (Gigantochloa scortechinii)

The development of composites using various filler material increased significantly nowadays. Composite materials need to implement the biological and mechanicals impact in their life cycle. The carbon black (CB) and activated carbon (AC) from bamboo (Gigantochloa scortechinii) were used as filler in polyester composites. CB and AC were pyrolized to 700°C and activated with ZnCl₂. The composites were prepared with 40% filler loading. The degradation of the composites CB and AC (mechanical properties) to the soil burial test was determined. Tensile, flexural, impact and mass changes of the buried samples were investigated. The deterioration of the samples affected by the biological attack was confirmed by SEM studies. The assessment was done after 0, 3, 6, and 12 months of the biological exposure and the results were compared with the composites filled CaCO₃ (commercial filler) and cast polyester resin (as control). POLYM. COMPOS. 28:6–14, 2007. © 2007 Society of Plastics Engineers     

A transgressive brown rice mediates favourable glycaemic and insulin responses

BACKGROUND: We evaluated glycaemic response of a brown rice variant (BR) developed by cross‐breeding. Subjects (n = 9) consumed 50 g carbohydrate equivalents of BR, white rice (WR) and the polished brown rice (PR) in comparison to 50 g glucose reference (GLU) in a cross‐over design. Plasma glucose and insulin at 0, 15, 45, 60, 90, 120 and 180 min were measured and incremental area under the curve (IAUC) and indices for glucose (GI) and insulin (II) calculated. RESULTS: BR compared to PR or WR produced the lowest postprandial glycaemia (GI: 51 vs 79 vs 86) and insulinaemia (II: 39 vs 63 vs 68) irrespective of amylose content (19 vs 23 vs 26.5%). Only BR was significantly different from GLU for both plasma glucose (P = 0.012) and insulin (P = 0.013) as well as IAUC_glu (P = 0.045) and IAUC_ins (P = 0.031). Glycaemic and insulinaemic responses correlated positively (r = 0.550, P < 0.001). Linear trends for IAUC_glu and IAUC_ins indicated a greater secretion of insulin tied in with a greater glycaemic response for WR (r² = 0.848), moderate for PR (r² = 0.302) and weakest for BR (r² = 0.122). CONCLUSION: The brown rice variant had the lowest GI and II values but these advantages were lost with polishing. Copyright © 2011 Society of Chemical Industry     

Bandwidth Partitioning and SINR Threshold Analysis of Fractional Frequency Reuse in OFDMA Cellular Networks for Real Time and Best Effort Traffic

To achieve high capacity in cellular networks, frequency reuse factor of unity is used. However, it suffers from heavy co-channel interference at cell edge regions. This leads to poor Signal to Interference plus Noise Ratio (SINR) and hence poor performance. fractional frequency reuse (FFR) is one of the methods being considered to improve cell edge performance. In this work we present the impact of SINR threshold and bandwidth partitioning on the successful deployment of FFR scheme. We have considered both real time (RT) and best effort (BE) traffic. In FFR, the total frequency resource is divided logically into cell center and cell edge user bands. However, while frequency resource is partitioned into two segments, the amount of bandwidth required by cell center and cell edge users is quite different and influences the system performance. We developed the semi analytical approach to evaluate the average bandwidth required by cell center and edge band users. From the analysis and simulation results it is seen that while grade of service (GoS) fair based method of choosing bandwidth partitioning ratio is best for RT traffic, while the only feasible method for BE traffic is dividing the bandwidth based on probability of a user to be in a given band which we termed as ‘Probability’ method.     

Bubble-induced circulation and associated boundary heat transfer

The mechanism of heat transfer from a bubbling liquid pool to an inclined side wall is considered. The process is relevant to the question of Mark-I liner melt-through due to contact with a high-temperature melt of reactor core materials, the bubbling being due to the decomposition of the concrete floor. We demonstrate experimentally that the recirculation caused by the two-phase lift creates a single-phase (liquid) boundary-layer flow along the inclined boundary which is responsible for heat transfer. An initial attempt to analytically quantify this process is also presented.     

Data Aided Iterative Channel Estimation in OFDM Systems Using a Controlled Superimposition of Training Sequences

This work pertains to the use of superimposed training for channel estimation in orthogonal frequency division multiplexing (OFDM) based systems. An iterative time domain Least Squares based channel estimator is proposed. The estimator is generalized to provide scope for exploiting the coherence time and the coherence bandwidth of the channel. By exploiting the periodicity of the training sequences in the time domain and inserting zeros instead of data at some of the training sequence subcarrier locations depending on the desired estimation accuracy, a controlled superimposition technique is proposed. This method includes the flexibility to trade off between bandwidth efficiency and performance without any change in the structure of the channel estimator. The mean squared estimation error (MSEE) performance of such a system is mathematically analyzed and a training sequence selection criterion optimizing the same is proposed. The simulation performance of the scheme is presented in terms of the MSEE and also its impact on the bit error rate is shown. Such a scheme is attractive in high data rate scenarios in closed loop OFDM systems.     

Effects of montmorillonite on the electron beam irradiated alumina trihydrate added polyethylene and ethylene vinyl acetate nanocomposite

This study aims at investigating the effects of montmorillonite (MMT) nanocomposite on the electron beam irradiated alumina trihydrate flame retardant added polyethylene and ethylene vinyl acetate blends (FRLE). The addition of MMT into FRLE blends has increased the limiting oxygen index (LOI%), which corresponds the improvement of flame resistivity, whereas increasing amount of MMT and irradiation dosage were found moderately influenced LOI% of the blends. However, incorporation of MMT has shown reinforcing effect to the FRLE, where the tensile strength for the samples subjected to 150 and 250 kGy irradiation have increased for 10.7 and 27%, respectively. In addition, increasing loading level of MMT and irradiation dosage caused inferior effects to the surface and volume resistivity of FRLE as high as four folds. This is due to the enhancement of transportability of MMT ionic in polymer matrix that caused the reduction of resistivity of FRLE. POLYM. COMPOS., 33:1883–1892, 2012. © 2012 Society of Plastics Engineers     

Channel Estimation in OFDM Systems Using a Controlled Superimposition of Training Sequences

This work pertains to the use of superimposed training (ST) for channel estimation in orthogonal frequency division multiplexing (OFDM) based systems. A time domain coherent averaging based channel estimator is derived from the least squares criterion. By exploiting the periodicity of the training sequences in the time domain and inserting zeros instead of data at some of the training sequence subcarrier locations depending on the desired estimation accuracy, a controlled superimposition technique is proposed. This method includes the flexibility to trade off between bandwidth efficiency and performance. The mean squared estimation error (MSEE) performance of such a system is mathematically analyzed and a training sequence selection criterion optimizing the same is proposed. The simulation performance of the scheme is presented in terms of the MSEE and the bit error rate (BER) of the OFDM system. Such a scheme is attractive in high data rate scenarios in closed loop OFDM systems.