Effects of Dilute Acid Pretreatment on Chemical and Physical Properties of Kenaf Biomass

In the current research, kenaf represents an agricultural biomass that possesses enormous potential for industrial applications. Because of its complex structure, which is composed of cellulose, hemicellulose, and lignin, pretreatment process was conducted. Here, dilute acid pretreatment process was conducted, statistically using the response surface method, which included three parameters: mass of biomass (g), temperature (°C), and time (min). About 2 g of kenaf biomass was treated with 2% dilute sulphuric acid, and it was found to have higher glucose conversion (25.3%) when the process was conducted for 60 min at the temperature of 180°C. The main aim of the current research is to investigate the chemical and physical changes of kenaf biomass before and after the pretreatment. The changes could be clearly seen in the cellulose, hemicellulose, and lignin composition before and after the pretreatment, which were evaluated via TAPPI standard test methods. Morphological observation under scanning electron microscope confirmed the changes that took place on the kenaf biomass from complex to simple surface structure. Fourier transform infrared analysis confirmed the presence of cellulose, hemicellulose, and lignin contents of the kenaf biomass before and after pretreatment. Crystallinity of the treated kenaf biomass also increased from 46.6% to 70.0%, as evidenced from X-ray diffractometer analysis.     

Flow pattern and hydraulic performance of the REDAC Gross Pollutant Trap

This paper discusses the flow pattern and hydraulic performance of a Gross Pollutant Trap (GPT), designed and patented by River Engineering and Drainage Research Centre (REDAC) at Universiti Sains Malaysia. Stormwater problems have become more severe due to the increase in urbanization. The increase in the amount of impervious surface in urban areas produces more stormwater runoff, that is carried to the receiving bodies of water. The higher runoff volume also carries more pollutants (gross pollutants, sediments, and nutrients) from the contributing catchment area. Coarse sediments transported by stormwater runoff have negative effects on the receiving body of water and the aquatic environment by covering up aquatic habitats and clogging waterways. One of the challenges in designing a GPT for urban stormwater drainage is providing effective trapping without hindering the hydraulic function of the channel, thus, avoiding overspill or flooding. The current study presents a GPT design to meet these specific requirements of trapping efficiency and hydraulic function. The current GPT overcame the common problem of overspilling of gross pollutants in GPT by the introduction of additional overspill compartments that can handle excessive runoff and improve pollutant trapping in higher flow conditions. In laboratory testing, the prototype GPT was capable of achieving good trapping efficiency (over 80% for gross pollutants and over 60% for coarse sediments) without causing any overspill.     

Viscosity analysis of polypropylene‐kaolin composites measured using single‐screw extruder

Deviations between data for the apparent and true viscosity measurement are commonly observed in the rheological studies of thermoplastics. To validate the significance on the usage of these data on the processing side, filling analysis for the apparent viscosity and true viscosity of polypropylene‐kaolin (PP‐kaolin) composites was conducted by using CadMold® software on the dumbbell Computer Aided Design model for comparative purposes. The raw apparent viscosity data were generated from a single‐screw extruder by using different sets of die geometries. Bagley and Rabinowitsch corrections were implemented to get a corrected set of true viscosity measurements. It was found that the true viscosity curves are lower compared with the apparent viscosity curves of PP‐kaolin. By constructing the corresponding data from PP‐kaolin composite rheological results, it was discovered that the high viscosity of the apparent viscosity melt data has shown a large variation in the mold distributions filling temperature, reduces the total pressure loss and melt shear stress, and increases the melt velocity during mold filling. Although the corrections were made on the calculated results, however, the significance is relatively small and it does not prove the changes in the overall physical property of the composite. Therefore, correcting the data by using the Bagley and Rabinowitsch corrections is not necessary in mold‐filling analysis. J. VINYL ADDIT. TECHNOL., 20:275–283, 2014. © 2014 Society of Plastics Engineers     

Enhanced ductility and tensile properties of hybrid montmorillonite/cellulose nanowhiskers reinforced polylactic acid nanocomposites

Montmorillonite (MMT)/cellulose nanowhiskers (CNW) reinforced polylactic acid (PLA) hybrid nanocomposites were prepared by solution casting. CNW were isolated from microcrystalline cellulose using a chemical swelling method. An initial study showed that the optimum MMT content, for mechanical properties, in a PLA/MMT nanocomposite is five parts per hundred parts of polymer (phr). Various amounts of CNW were added to the optimum formulation of PLA/MMT to produce PLA/MMT/CNW hybrid nanocomposites. FT-IR analysis indicated the formation of some polar interactions, resulting in enhanced tensile properties of the hybrid nanocomposites. The highest tensile strength for the hybrid nanocomposites was obtained for a 1 phr CNW content. Young’s modulus was also found to increase with an increasing CNW content. Interestingly, the strain to failure (or ductility) of the hybrid nanocomposites increased significantly from ~10 to ~90 % with the addition of 1 phr CNW. This increase in ductility was proposed to be due to the nucleation of crazes and the formation of shear bands in the PLA.     

Dual‐band aperture‐coupled rectenna for radio frequency energy harvesting

The article presents a dual‐band aperture‐coupled rectenna for radio frequency (RF) energy harvesting at 2.45 and 5 GHz application. The rectenna consists of a dual‐band π‐shaped slot‐etched aperture‐coupled antenna, designed at the lower substrate of two FR4 substrate layers and a dual‐band rectifier. The proposed antenna design also introduces the harmonic suppression of third‐ and higher order harmonics, ranging from 6 up to 10 GHz from the asymmetrical stubs design at the transmission feedline. The dual‐band rectifier is designed to operate at 2.45 and 5 GHz frequency, successfully achieving high conversion efficiency at 68.83% and 49.90% with the optimum load resistor of value 700 Ω and 1.1 kΩ. The minimum DC voltage of 0.167 and 0.236 V with 0 dBm RF input power can be increased when greater RF power is being applied to it, increasing its flexibility to cater various low‐power applications.     

Microfluidic biochemical sensor based on circular SIW‐DMS approach for dielectric characterization application

This work proposes an advancement of microwave planar resonator sensor with high sensitivity for microfluidic dielectric characterization. The physical design was employed based on circular substrate integrated waveguide (CSIW) with an integration of defected microstrip structure (DMS). This approach can be applied to accelerate the dielectric detection, structure miniaturization and material differentiation. The presented sensor operates based on variations in the dielectric properties of solvents in the vicinity of a planar open‐ended microstrip resonator device. Further analysis in volume and concentration were performed to validate the reliability of the sensor. Validation and functionality of the sensor were investigated by experimental and results comparison. A mathematical model was developed to determine the dielectric constant and the loss tangent of the microfluidic samples. The average error detection has a lower percentage value of 0.11% by comparison to the commercial and ideal dielectric properties of the aqueous samples. The maximum relative error detection, ±0.37% implied better accuracy compared to the existing resonator sensors with more than 400 of the Q‐factor. The proposed CSIW‐DMS sensor was found to give higher accuracy and detection response; besides easier to fabricate, and compatible for integration with other electronic components in an RF sensor for variety of applications.     

Statistical Modeling of the 3D Geometry and Topology of Botanical Trees

We propose a framework for statistical modeling of the 3D geometry and topology of botanical trees. We treat botanical trees as points in a tree‐shape space equipped with a proper metric that captures the geometric and the topological differences between trees. Geodesics in the tree‐shape space correspond to the optimal sequence of deformations, i.e. bending, stretching, and topological changes, which align one tree onto another. In this way, the 3D tree modeling and synthesis problem becomes a problem of exploring the tree‐shape space either in a controlled fashion, using statistical regression, or randomly by sampling from probability distributions fitted to populations in the tree‐shape space. We show how to use this framework for (1) computing statistical summaries, e.g. the mean and modes of variations, of a population of botanical trees, (2) synthesizing random instances of botanical trees from probability distributions fitted to a population of botanical trees, and (3) modeling, interactively, 3D botanical trees using a simple sketching interface. The approach is fast and only requires as input 3D botanical tree models with a known upright orientation.     

A survey of mmWave user association mechanisms and spectrum sharing approaches: an overview,open issues and challenges,future research trends

Fifth generation (5G) cellular networks promise to support multi-radio access technologies (multi-RATs) with low and high frequencies aiming at delivering good coverage, several gigabits data rate, and ultra-reliable services. In this context, user-association and resource allocation appear to be a huge challenge due to the variety of specifications and varied propagation environments. In this treatise, the focus is on the technical and administrative difficulties of the adoption of user association (UA) mechanism and spectrum sharing approach (SSA) in millimeter wave (mmWave) systems, for example, the technical design considerations and their underlying options, as well as their impact on users and network performance. In addition, details on the importance of the rules and regulations of SSA are presented. This study also identified a few possible design solutions and potential promising technologies in both UA and SSA. In the context of UA, several mechanisms are identified, such as backhaul-, caching-, and hybrid multi-criteria-aware UA to achieve seamless connectivity and to enhance the network utility. In the context of SSA, this study pinpoints varied subjects that need to be explored, such as joint efficient rules and regulations enactment, assessment of fairness and independence in multi-independent mobile network operators (multi-IMNOs) that support SSA, as well as the implementation of hybrid-SSA via Virtualized Cloud Radio Access Network. Finally, attention is drawn to several key conclusions to enable readers and interested researchers to learn about the most controversial points of mmWave 5G cellular networks.

     

Effects of Ageing on Selected Cooking Quality Parameters of Rice

Ageing can improve cooking quality of rice by influencing major cooking quality parameters i.e., kernel expansion, water absorption, alkali digestion value, and gelatinization temperature along with changes in internal structure of rice grains. In this research, the effects of natural and artificial ageing on the selected cooking quality parameters of two Malaysian rice cultivars, named Mahsuri and Puteri, were studied. A relation was observed between water absorption and elongation ratio in both varieties under different aging conditions. Alkali digestion value and gelatinization temperature were also influenced by varieties and ageing conditions. This study revealed the potentiality of ageing for the improvement of rice cooking quality.