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.     

High‐efficiency indium gallium nitride/Si tandem photovoltaic solar cells modeling using indium gallium nitride semibulk material: monolithic integration versus 4‐terminal tandem cells

In this work, we present a double‐junction solar cell with a crystalline silicon solar cell as a bottom junction and an indium gallium nitride‐based semibulk‐structured solar cell as a top junction. Using SILVACO Atlas and taking into account polarization effects in III‐N materials, we have shown that 50% of indium is needed to ensure the current matching between the top cell and the bottom cell in 2‐terminal configuration. Such high indium composition is technologically challenging to grow. Thus, we have also modeled a 4‐terminal configuration showing the same performance (i.e. conversion efficiency close to 29%) where only 25% of indium content is needed. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Light and scanning electron microscopy-based foliar morpho-anatomical comparison of selected family Rosaceae members distributed in District Lahore,Punjab, Pakistan

In the present study morpho-anatomical characterization of selected Rosaceae members distributed in District Lahore was performed. Light and scanning electron microscopy was used for systematic characterization of the selected 19 species. Distinguished morpho-anatomical features such as size and shape of epidermal cells, size and type of stomatal cells, size and shape of trichomes, oil droplets, and silica bodies were contrasted. Results reported remarkable variations which could be taxonomically useful in identification of these members. Polygonal epidermal cells were observed in Eriyobotraya japonica, Potentilla bifurca, Potentilla supina, and Prunus amygdalus. However, Prunus cerasus possessed irregular-shaped epidermal cells that can be distinguished from hexagonal epidermal cells of Prunus persica. Similarly, stomatal type varied among some members. Paracytic or perisocytic stomata were observed in E. japonica whereas P. bifurca observed paracytic and anisocytic stomata. Lengths of guard cells were also of variable sizes. The average length of guard cells ranged from 53 (52–54) μm to 74 (73–75) μm in abaxial view. Potentilla supina had biggest, while Rosmarinus officinalis had tiny guard cells. Trichomes were tubular, stellate, cylindrical, ribbon-like, glandular, and nonglandular. Silica bodies in the present investigation were bilobed, rounded, and oval-shaped. It is inferred that diverse anatomical features proved to be valuable taxonomic tools that could be fruitfully helpful in identification of plants at specific as well as generic level.     

Scanning electron microscopic imaging of palynological metaphors: A case study of family Poaceae taxa

This study highlighted the taxonomic utilization of palynological metaphors for selected members (53) of family Poaceae. Multiple microscopic technique light and scanning electrons had been employed for detailed analysis. Results reported monad pollen type in all studied 53 members, which showed its limited taxonomic value up to family level. In relation to shape of pollen both polar and equatorial views strikingly differed from each other. Like semi angular pollen observed in Dactyloctenium aegyptium (L.) Wild. whereas round-minutely irregular pollen in Lolium temulentum L. Polar and equatorial diameter also showed variation, that is, Desmostachya bipinnata (L.) Stapf. can be differentiated from Sorghum bicolor (L.) Moench on diameter variation basis. A pore characteristic does not show much qualitative variation; however pore sizes differ species to species. The most frequently scarbate sculpturing was observed in 28 species followed by verrucate. Hence it can be said that pollen shape, polar, and equatorial diameters, pore size, P/E ratio, pore sculpturing are of good taxonomic value and holds a significant position in identification and delimitation of Poaceae taxa.     

Effects of different Raman pumping schemes on stimulated Brillouin scattering in a linear cavity

The effects of backward, forward, and bidirectional Raman pumping schemes on stimulated Brillouin scattering (SBS) is investigated in this study. By using a linear cavity, we utilize residual Brillouin pump (BP) and Raman pump (RP) power after each transmission through a 25 km single-mode fiber (SMF) used as a gain medium. The SBS threshold power is reduced in the forward, backward, and bidirectional Raman pumping schemes by 2.5, 1.75, and 2.75 dB, respectively when the 1480 nm RP power is fixed at 150 mW and the BP wavelength is 1580 nm. Surprisingly, it is revealed that the SBS threshold reduction depends strongly and solely on Raman gain and it is independent of the Raman pumping schemes. In addition, the effect of Raman amplification on SBS is more effective at the SBS threshold, especially in the bidirectional and forward schemes.     

Towards optimal synchronization in NFV-based environments

Network Function Virtualization (NFV) is known for its ability to reduce deployment costs and improve the flexibility and scalability of network functions. Due to processing capacity limitations, the infrastructure provider may need to instantiate multiple instances of the same network function. However, most of network functions are stateful, meaning that the instances of the same function need to keep a common state and hence the need for synchronization among them. In this paper, we address this problem with the goal of identifying the optimal synchronization pattern between the instances in order to minimize the synchronization costs and delay. We propose a novel network function named Synchronization Function able to carry out data collection and further minimize these costs. We first mathematically model this problem as an integer linear program that finds the optimal synchronization pattern and the optimal placement and number of synchronization functions that minimize synchronization costs and ensure a bounded synchronization delay. We also put forward three greedy algorithms to cope with large-scale scenarios of the problem, and we explore the possibility to migrate network function instances to further reduce costs. Extensive simulations show that the proposed algorithms efficiently find near-optimal solutions with minimal computation time and provide better results compared to existing solutions.     

One Shot of the Hydrothermal Route for the Synthesis of Zeolite LTA Using Kaolin

Journal of Inorganic and Organometallic Polymers and Materials - The zeolite LTA (Z-LTA) was successfully produced from the synthesis of kaolin and well-crystallized using a hydrothermal method....