Bamboo fabric reinforced polypropylene and poly(lactic acid) for packaging applications: Impact,thermal, and physical properties

The main objective of this study is to explore the potential of using totally green composites made from renewable resources in packaging applications as compared to conventional thermoplastics. In this work, we undertook a comparative study of the functional properties related to the packaging applications of bamboo fabric–Polypropylene (PP) and bamboo fabric–Poly(lactic acid) (PLA) composites. Results indicate that Charpy impact strength was increased from 37.5 to 126 J/m for bamboo fabric–PLA composites and 204 to 278 J/m for bamboo fabric–PP composites compared to the pure polymers. Drop weight impact tests were also performed and the same trend was observed. Results of thermogravimetric analysis, differential scanning calorimetry, and heat deflection temperature analysis have shown that the addition of bamboo fabric improved the thermal resistance of these composites. Results indicate that bamboo fabric is a potential reinforcement for PLA composites, but possible packaging applications should avoid high humidity environment. POLYM. COMPOS., 35:1888–1899, 2014. © 2014 Society of Plastics Engineers     

Millimeter wave complex refractive index,complex dielectric permittivity and loss tangent of extra high purity and compensated silicon

Single crystal high resistivity (11,000 ohm-cm) boron doped silicon was found to exhibit lowest absorption loss at room temperature (25 C) in the entire millimeter wave region. At 140 GHz it's loss tangent value is as low as 40 microradians. The study of dielectric properties of silicon as a function of resistivity reveals that the low frequency free carrier absorption present in all silicon (and other semiconductors) vanishes with increasing resistivity. It is then possible to use such a silicon in substrate applications in microwave integrated circuitry. The unique broadband dispersive Fourier transform spectroscopic technique was utilized for these measurement.     

A Green Clustering Protocol for Mobile Sensor Network Using Particle Swarm Optimization

Energy consumption of sensor nodes is one of the crucial issues in prolonging the lifetime of wireless sensor networks. One of the methods that can improve the utilization of sensor nodes batteries is the clustering method. In this paper, we propose a green clustering protocol for mobile sensor networks using particle swarm optimization (PSO) algorithm. We define a new fitness function that can optimize the energy consumption of the whole network and minimize the relative distance between cluster heads and their respective member nodes. We also take into account the mobility factor when defining the cluster membership, so that the sensor nodes can join the cluster that has the similar mobility pattern. The performance of the proposed protocol is compared with well-known clustering protocols developed for wireless sensor networks such as LEACH (low-energy adaptive clustering hierarchy) and protocols designed for sensor networks with mobile nodes called CM-IR (clustering mobility-invalid round). In addition, we also modify the improved version of LEACH called MLEACH-C, so that it is applicable to the mobile sensor nodes environment. Simulation results demonstrate that the proposed protocol using PSO algorithm can improve the energy consumption of the network, achieve better network lifetime, and increase the data delivered at the base station.     

The potential application of natural zeolite for greywater treatment

Natural zeolites are good potential material for water and wastewater treatment. It is due to the advantages of low cost, ion-exchange and adsorption capability of the natural zeolites. It can also be modified and regenerated. This paper thus looks at efforts made in exploring the potential application of natural zeolites and modified natural zeolites in water and wastewater treatment especially for reducing or removing contaminants in greywater, a type of wastewater originated from bathrooms and laundries in household. The material to be reviewed in this paper includes (i) major greywater contaminants and (ii) the potential of natural zeolites for greywater treatment.     

Enrichment of carotene from palm oil by organic solvent nanofiltration

Palm oil is one of the richest sources of natural plant carotene with typical concentration of about 0.5–0.7 g/L. Unfortunately, during physical refining of palm oil, most of the carotenes were destroyed by high temperatures and this represents a loss of potential source of natural carotene. Various techniques have been developed to extract and recover carotenes from palm oil, however these processes often require high energy usage, and usually renders the oil useless for further consumption. Recently, organic solvent nanofiltration (OSN) has become an important method for molecular separation particularly for the separation of low molecular weight bioactive compounds. This work presents the application of OSN membranes for the separation of carotene from a crude palm oil/solvent system. Several commercial OSN membranes (DuraMem and PuraMem series) fabricated from polyimide were evaluated for their separation abilities. PuraMem 280 showed the best selectivity performance, with the concentration of carotene in permeate oil increased from 0.60 to 0.79 g/L when hexane was used as the solvent. Runs by using DuraMem 150, DuraMem 300 and DuraMem 500 showed low or no selectivity between carotene and triglyceride in all solvents. It was found that the rejection of carotene depends strongly on the type of solvents. A coupled solution diffusion and film theory was also utilized to model carotene transport through OSN membrane. It was demonstrated that OSN can serve as an alternative for the direct carotene recovery from palm oil and can be potentially applied for other minor compounds recovery from vegetable oils.     

Adaptive Priority Sliding Admission Control and Scheduling Scheme for DCF and EDCA WLANs

In this paper an Adaptive Priority Sliding Admission Control and Scheduling (APSAS) scheme is proposed to provide QoS over the existing IEEE802.11 WLANs which operate on Distributed Coordination Function (DCF) and Enhanced Distributed Channel Access (EDCA) mechanisms. The roles of this scheme are generally two folds: (1) To control the number of delay-sensitive real time flows that can be admitted into the WLAN Basic Service Set network and (2) To adjust the priority of selected real time flows in order to accommodate more real time flows without violating the QoS requirement. Extensive simulation studies show that APSAS improves the total throughput, flow throughput ratio, packets end-to-end delay, and jitter of the real time applications when compared with conventional best effort and scheduling-enhanced DCF/EDCA. APSAS also offers near to unity average throughput ratio, lower mean VoIP end-to-end packet delay (<130 ms) and lower mean video packet jitter (<130 ms) over DCF and EDCA.     

Molecular Weight Determination of Palm Olein Polyols by Gel Permeation Chromatography Using Polyether Polyols Calibration

Natural oil polyols have been intensively developed and successfully used for the production of various polymers, notably polyurethanes. The need to access the average molecular weight (MW) and the MW distribution (MWD) has led to the efforts to have a precise and reliable determination method. A series of commercial polyether polyols, with well‐defined MW, was used as a gel permeation chromatography (GPC) calibration standard to determine the MW of palm olein polyols. This GPC analysis was compared to the one calibrated against the commercially available polystyrene (PS) standards and to the number‐average molecular weight (M_n) obtained via vapor pressure osmometry (VPO) technique. For example, the M_n obtained for palm olein polyol E‐135 calibrated against polyether polyols was 2,537 Da, which was closer to the M_n via VPO (1,618 Da), than the M_n obtained using PS as calibration standards (3,836 Da). Hence, this GPC analysis using polyether polyols as calibration standards can offer reassured determination of MWD of palm olein polyols.     

Characteristics and cadmium extraction performance of PVC/Aliquat 336 electrospun fibres in comparison with polymer inclusion membranes

Electrospun fibres and polymer inclusion membranes (PIMs) were prepared from polyvinyl chloride (PVC) and Aliquat 336. Morphological and thermomechanical properties of the electrospun mats differed notably from those of PIMs. The plasticizing effect of Aliquat 336 on electrospun PVC/Aliquat 336 fibres was confirmed by the shifting of the glass transition temperature (T_g). By contrast, Aliquat 336 did not act as a plasticizer in PIMs as T_g was independent of Aliquat 336 concentration. Cadmium extraction to electrospun fibres could occur at a lower Aliquat 336 content (i.e. 6 wt.%) compared with PIMs. At 40 wt.% Aliquat 336 content, both PIMs and electrospun fibrous mats exhibited similar extraction rate.     

Analysis of Surface Parameters and Vibration of Roller Bearing

The surface of the inner race of a detachable roller bearing is monitored periodically to determine the deterioration pattern under normal conditions together with the vibration level. The surface of the inner race is scanned using an infinite focus microscope to evaluate surface properties utilizing the 2D and 3D parameters. Both parameters successfully assess the surface degradation and wear of the bearing surface. Using the Dowson-Higginson equation on elastohydrodynamic lubrication, the theoretical lubrication film was calculated and the lubrication regimes identified. A high vibration level can be associated with surface roughness properties and relative lubrication regime. This work highlights the relationship between the bearing vibration level and the bearing inner race surface parameters. The two surface parameters with the highest Pearson correlation coefficient with the vibration level are the areal surface roughness S_a (0.997) and the average roughness R_a (0.936).     

Purification and characterization of membrane-bound polyphenoloxidase (mPPO) from Snake fruit [Salacca zalacca (Gaertn.) Voss]

Membrane-bound polyphenoloxidase (mPPO) an oxidative enzyme which is responsible for the undesirable browning reaction in Snake fruit (Salacca zalacca (Gaertn.) Voss) was investigated. The enzyme was extracted using a non-ionic detergent (Triton X-114), followed by temperature-induced phase partitioning technique which resulted in two separate layers (detergent-poor phase at the upper layer and detergent-rich phase at the lower layer). The upper detergent-poor phase extract was subsequently fractionated by 40–80% ammonium sulfate and chromatographed on HiTrap Phenyl Sepharose and Superdex 200 HR 10/30. The mPPO was purified to 14.1 folds with a recovery of 12.35%. A single prominent protein band appeared on native-PAGE and SDS–PAGE implying that the mPPO is a monomeric protein with estimated molecular weight of 38 kDa. Characterization study showed that mPPO from Snake fruit was optimally active at pH 6.5, temperature 30 °C and active towards diphenols as substrates. The K_m and V_max values were calculated to be 5.46 mM and 0.98 U/ml/min, respectively, when catechol was used as substrate. Among the chemical inhibitors tested, l-cysteine showed the best inhibitory effect, with an IC₅₀ of 1.3 ± 0.002 mM followed by ascorbic acid (1.5 ± 0.06 mM), glutathione (1.5 ± 0.07 mM), EDTA (100 ± 0.02 mM) and citric acid (186 ± 0.16 mM).