Surface ultrastructure of larval mouthpart sensilla of the muga silkmoth,Antheraea assamensis,an endemic species of North‐East India

Scanning electron microscopy of different larval stages of the muga silk moth Antheraea assamensis revealed the presence of sensilla chaetica, sensilla trichoidea, sensilla styloconica, gustatory sensilla, sensory pegs, placoid sensilla, etc., on their mouth parts. Some variations were observed in the number and sub‐types of sensilla in certain larval stages indicating some differences in sensitivity of the worms in different instars to the food plant and microhabitat. Microsc. Res. Tech., 2010. © 2010 Wiley‐Liss, Inc.     

Crystallography of Interfaces and Grain Size Distributions in Sr‐Doped LaMnO3

Grain‐boundary plane distributions (GBPDs), grain size distribution (GSDs), and upper tail departure from log‐normal GSDs were quantified in dense and porous La_0.8Sr_0.2MnO₃ samples to understand expected microstructures in solid oxide fuel cells. Samples were sintered at 1450°C for 4 h and then annealed between 800°C and 1450°C. The GBPDs and normalized GSDs reached steady state during sintering and little variation occurred during annealing. The GBPDs were nearly isotropic, with the relative areas of {001} planes being slightly higher than random (and the relative areas of {111} planes being less than random). The porous sample had an almost identical GBPD, whereas the almost isotropic pore boundary plane distribution was essentially opposite to the GBPD. The upper tails of the experimental GSDs, and several theoretical distributions, were characterized using peaks‐over‐threshold analysis. Dense samples, and all normal grain growth models, exhibit lower frequencies of large grains in the upper tail than would a log‐normal distribution, and the experimental distributions are similar to the Mullins distribution. Porous samples, however, have an anomalous increased frequency of large grains in the upper tail, as compared to all the model distributions, even though other metrics of the microstructure indicate the dense and porous systems are similar.     

Mechanical characteristics of glass fibre reinforced polymer made of furfuryl alcohol bio-resin

Conventional fiber reinforced polymers (FRPs) require polymers such as epoxies that are not biodegradable, which have a significant impact on the environment. This study aims at replacing conventional polymers with bio-polymers which are more sustainable. The study investigates the tensile mechanical properties of glass-FRP (GFRP) laminates fabricated by wet layup using two types of organic furfuryl alcohol bio-resins extracted renewable resources, such as corncobs. Results are compared to control specimens fabricated using conventional epoxy resin. The study investigates the effects of catalyst type and dosage as well as the curing time on the tensile strength and modulus of the GFRP. The study also investigates the optimal overlap splice of the laminates. It was shown that by careful selection of viscosity of bio-resin, and type and dosage of catalyst similar mechanical properties to epoxy-GFRP can be achieved. The optimal catalyst proportion was 3 % by weight. Full strength occurred after 13 days curing but 84 % occurred in 2 days. The optimal lap splice length was 200 mm, however, the maximum strength was only 68 % of the full ultimate tensile strength as bond failure always governs at the splice.     

Ant Colony Optimization Based Sub-channel Allocation Algorithm for Small Cell HetNets

Two-tier heterogeneous networks (HetNets) composed of a conventional macrocellular network and small cell networks (SCNs) have been proposed in the literature with the aim to extend indoor coverage and realize efficient radio resource usage. As SCN shares the same frequency band with the underlying macrocell, the cross tier interference needs to be mitigated since the inter-SCN and cross tier interference at the SCN boundary may result in undesirable network performance degradation. In this paper, we propose an intelligent physical resource block (PRB) allocation as a solution to mitigate the downlink intra-SCN interference as well as the inter-tier interference in OFDM-based systems. The allocation of the PRBs to the network users is formulated as a graph coloring problem, and solved using an ant colony optimization (ACO)-based approach. Simulation results are provided, showing that our ACO-based algorithm outperforms the Received Power-based Allocation (RPA) and Received SINR-based Allocation (RSA) algorithms in terms of average SINR experienced by network users, outage probability, and number of required PRBs.     

Lightweight Localization Using Trilateration for Sensor Networks

Localization is an unavoidable procedure in location aware sensor networks. In such networks, management of a large amount of location information along with its processing and updating is highly desirable at a central station of the network. In this paper, we have discussed the implementation of software layer to be run on various types of sensor nodes in the localization network, which has been dealt with extensively along with some of the addressed problems and their respective solutions. In addition, the article discusses implementation of an already mathematical formulation of least squares trilateration, which has not yet been attempted in the space of wireless sensor networks. To support our clam we performed experimental analysis on \(telosb\) motes. Experimental results of proposed framework shows that average error with respect to the physical location estimation can be reduced upto 46.66 % using 4 anchor node as compare to three anchor nodes at outdoor scenario and upto 40 % in indoor scenario.     

Improved Transformation and Regeneration of Indica Rice: Disruption of SUB1A as a Test Case via CRISPR-Cas9

Gene editing by use of clustered regularly interspaced short palindromic repeats (CRISPR) has become a powerful tool for crop improvement. However, a common bottleneck in the application of this approach to grain crops, including rice (Oryza sativa), is efficient vector delivery and calli regeneration, which can be hampered by genotype-dependent requirements for plant regeneration. Here, methods for Agrobacterium-mediated and biolistic transformation and regeneration of indica rice were optimized using CRISPR-Cas9 gene-editing of the submergence tolerance regulator SUBMERGENCE 1A-1 gene of the cultivar Ciherang-Sub1. Callus induction and plantlet regeneration methods were optimized for embryogenic calli derived from immature embryos and mature seed-derived calli. Optimized regeneration (95%) and maximal editing efficiency (100%) were obtained from the immature embryo-derived calli. Phenotyping of T₁ seeds derived from the edited T₀ plants under submergence stress demonstrated inferior phenotype compared to their controls, which phenotypically validates the disruption of SUB1A-1 function. The methods pave the way for rapid CRISPR-Cas9 gene editing of recalcitrant indica rice cultivars.     

An Adhesion-Dominated Rolling Friction Regime Unique to Micro-scale Ball Bearings

We demonstrate that micro-scale rolling bearings exhibit friction and wear properties markedly different from their macro-scale counterparts. A microfabricated testing platform uses variable rolling element diameters or vapor-phase lubricated interfaces to independently test friction force with varying contact area and surface energy. A linear, consistent, relationship between friction force and contact area is observed among different rolling element diameters. When surface free energy is altered through the introduction of vapor-phase lubrication, an 83 % decrease in friction is observed. When coupled with observed ball material adhered to the raceway, there is strong evidence for adhesion-dominated rolling friction regime at the micro-scale.     

Growth and structural characterization of epitaxial Cu/Nb multilayers

Electron beam evaporation with optimized deposition parameters has been used to grow good quality epitaxial Cu/Nb nanoscale multilayered films on sapphire substrates. The quality of the epitaxial films, as measured by the intensities and widths of the X-ray diffraction peaks, increases with increasing deposition temperature. However, high deposition temperatures also enhance the tendency for layer pinch-off which eventually leads to spheroidization and growth of multilayer films with polycrystalline islands. Deposition temperatures and rates were optimized to produce the highest quality epitaxial films with continuous nanolayers, suitable for in situ deformation experiments in a synchrotron-based Laue micro-diffraction set up.     

Compression modeling of plain weave textile fabric using finite elements

Textile composite are used extensively in aerospace as they offer a 3D reinforcement in a single layer providing better mechanical properties in both in‐plane and transverse directions. This paper reports on the mechanical behavior of a plain weave textile fabric under the compressive loading. Unit cell geometry of the plain weave fabric structure is identified and its model is created using TexGen geometric modeling scheme developed by the University of Nottingham (U.K.). Later on its mechanical behavior is predicted using finite element modeling (FEM) based simulation software ABAQUS^® incorporating a transversely isotropic material law. Strain energy of the developed model has been compared with that of the published results and shows very good agreement. The analysis indicated that transverse‐longitudinal shear (TLS) modulus plays an important role in characterizing the behavior of the woven fabric under compression, while the friction between the yarns and longitudinal stiffness has less significant influence on compaction behavior. In order to ascertain the effectiveness of the developed model, exhaustive parametric studies have also been conducted to investigate the effect of transverse‐longitudinal shear modulus on some of the important parameters such as artificial strain energy, external work, frictional dissipation, internal energy, kinetic energy, strain energy and total energy of the model. The developed model has the capacity to predict and simulate the behavior of variety of fabric architectures based on their constituent yarn properties under various regimes of service loads.     

Cellular internalization of silver nanoparticles in gut epithelia of the estuarine polychaete Nereis diversicolor

Silver nanoparticles (AgNPs) are widely used which may result in environmental impacts, notably within aquatic ecosystems. As estuarine sediments are sinks for numerous pollutants, but also habitat and food for deposit feeders such as Nereis diversicolor, ingested sediments must be investigated as an important route of uptake for NPs. N. diversicolor were fed sediment spiked with either citrate capped AgNPs (30 ± 5 nm) or aqueous Ag for 10 days. Postexposure AgNPs were observed in the lumen of exposed animals, and three lines of evidence indicated direct internalization of AgNPs into the gut epithelium. With TEM, electron-dense particles resembling AgNPs were observed associated with the apical plasma membrane, in endocytotic pits and in endosomes. Energy dispersive X-ray analysis (EDX) confirmed the presence of Ag in these particles, which were absent in controls. Subcellular fractionation revealed that Ag accumulated from AgNPs was predominantly associated with inorganic granules, organelles, and the heat denatured proteins; whereas dissolved Ag was localized to the metallothionein fraction. Collectively, these results indicate separate routes of cellular internalization and differing in vivo fates of Ag delivered in dissolved and NP form. For AgNPs an endocytotic pathway appears to be a key route of cellular uptake.