Variation in Attraction to Host Plant Odors in an Invasive Moth Has a Genetic Basis and is Genetically Negatively Correlated with Fecundity

Lepidopteran insects are major pests of agricultural crops, and mated female moths exploit plant volatiles to locate suitable hosts for oviposition. We investigated the heritability of odor-guided host location behavior and fecundity in the cosmopolitan oriental fruit moth Grapholita (Cydia) molesta, an oligophagous herbivore that attacks fruit trees. We used a full-sib/half-sib approach to estimate the heritability and the genetic correlation between these two traits. Results document a considerable genetic basis for olfactory attraction of females (h 2 =0.37±0.17) and their fecundity (h 2 =0.32±0.13), as well as a genetic trade-off between female attraction and fecundity (r g =−0.85±0.21). These estimations were empirically corroborated by comparing two strains maintained in the laboratory for different numbers of generations. The long-term reared strain lost its olfactory discrimination ability but achieved significantly higher fecundity compared with the short-term reared strain. Our results highlight that genetic studies are relevant for understanding the evolution of odor-guided behavior in herbivore insects and for judging the promise of pest management strategies involving behavioral manipulation with plant volatile

Graded-size Si quantum dot ensembles for efficient light-emitting diodes

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PECVD low stress silicon nitride analysis and optimization for the fabrication of CMUT devices

Two technological options to achieve a high deposition rate, low stress plasma-enhanced chemical vapor deposition (PECVD) silicon nitride to be used in capacitive micromachined ultrasonic transducers (CMUT) fabrication are investigated and presented. Both options are developed and implemented on standard production line PECVD equipment in the framework of a CMUT technology transfer from R & D to production. A tradeoff between deposition rate, residual stress and electrical properties is showed. The first option consists in a double layer of silicon nitride with a relatively high deposition rate of ~100 nm min−1 and low compressive residual stress, which is suitable for the fabrication of the thick nitride layer used as a mechanical support of the CMUTs. The second option involves the use of a mixed frequency low-stress silicon nitride with outstanding electrical insulation capability, providing improved mechanical and electrical integrity of the CMUT active layers. The behavior of the nitride is analyzed as a function of deposition parameters and subsequent annealing. The nitride layer characterization is reported in terms of interfaces density influence on residual stress, refractive index, deposition rate, and thickness variation both as deposited and after thermal treatment. A sweet spot for stress stability is identified at an interfaces density of 0.1 nm−1, yielding 87 MPa residual stress after annealing. A complete CMUT device fabrication is reported using the optimized nitrides. The CMUT performance is tested, demonstrating full functionality in ultrasound imaging applications and an overall performance improvement with respect to previous devices fabricated with non-optimized silicon nitride

Strengthening of Wood-like Materials via Densification and Nanoparticle Intercalation

Recently, several chemical and physical treatments were developed to improve different properties of wood. Such treatments are applicable to many types of cellulose-based materials. Densification leads the group in terms of mechanical results and comprises a chemical treatment followed by a thermo-compression stage. First, chemicals selectively etch the matrix of lignin and hemicellulose. Then, thermo-compression increases the packing density of cellulose microfibrils boosting mechanical performance. In this paper, in comparison with the state-of-the-art for wood treatments we introduce an additional nano-reinforcemeent on densified giant reed to further improve the mechanical performance. The modified nanocomposite materials are stiffer, stronger, tougher and show higher fire resistance. After the addition of nanoparticles, no relevant structural modification is induced as they are located in the gaps between cellulose microfibrils. Their peculiar positioning could increase the interfacial adhesion energy and improve the stress transfer between cellulose microfibrils. The presented process stands as a viable solution to introduce nanoparticles as new functionalities into cellulose-based natural materials

Numerical Simulation and Experimental Characterization of Emitter Wrap through Solar Cells with Deep Grooved Base Contact (EWT-DGB)

Abstract In this work we present an Emitter Wrap Through cell with Deep Grooved Base contact (EWT-DGB), designed for both 1-sun and concentrating applications. The proposed approach, which consists in a deep grooved hole array composed by holes of two alternating doping type, allows both a reduction of the cell series resistance and an increase in collection efficiency also by using relatively thick substrates with low lifetime. The measured experimental data including dark J-V characteristics, figures of merit (FOMs) under illumination and external quantum efficiency (EQE) are compared to the results of 3-D drift-diffusion TCAD numerical simulations. Moreover, the impact of the hole spacing and of process-dependent physical parameters (interface defects) on FOMs is investigated by means of simulations

Silicon nanocrystals as a photoluminescence down shifter for solar cells

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