Low off-state Leakage Currents in AlGaN/GaN High Electron Mobility Transistors By Employing A Highly Stressed SiNx Surface Passivation Layer

In this study, the impact of the stress in SiNx surface passivation layers on off-state drain and gate leakage currents and off-state breakdown voltage in AlGaN/GaN High Electron Mobility Transistors (HEMTs) is assessed. The SiNx films were deposited at room temperature by inductively coupled plasma chemical vapour deposition (ICP-CVD). Compared to unpassivated devices, the off-state drain and gate leakage currents of AlGaN/GaN HEMTs is increased by up to 2 orders of magnitude for a 200 nm thick SiNx passivation layer with 309 MPa compressive stress. The use of a bilayer SiNx passivation scheme comprising 70 nm SiNx with 309 MPa compressive stress followed by 130 nm SiNx with 880 MPa compressive stress resulted in off-state drain and gate leakage currents reduced by up to 1 order of magnitude when compared to unpassivated devices

On the Ricci dark energy model

We study the Ricci dark energy model (RDE) which was introduced as an alternative to the holographic dark energy model. We point out that an accelerating phase of the RDE is that of a constant dark energy model. This implies that the RDE may not be a new model of explaining the present accelerating universe.Comment: 8 page

A wireless ECG plaster for real-time cardiac health monitoring in body sensor networks

10.1109/BioCAS.2011.61077632011 IEEE Biomedical Circuits and Systems Conference, BioCAS 2011205-20

Effect of post processing on the creep performance of laser powder bed fused Inconel 718

In this study, the creep performance of laser powder bed fusion manufactured Inconel 718 specimens is studied in detail and compared with conventional hot-rolled specimens alongside as-built then heat-treated and as-built then hot-isostatic pressed specimens. Hot-rolled specimens showed the best creep resistance, while the hot-isostatic pressed specimens yielded the worst performance, inferior to the as-built condition. Creep testing of all samples showed increased secondary creep rate was consistently correlated with a reduced life. Fractography revealed intergranular fracture was the primary failure mode for all as-built samples. Preferential intergranular precipitation in the case of the hot-isostatic pressed specimens during hot-isostatic pressing extensive intergranular cracking as the primary failure mechanism. Heat-treated specimens possessed only sparse intergranular precipitates, thereby explaining an improved creep lifetime. The hot-rolled specimens, having smallest grain size, showed the least extensive cracking, particularly in locations of finest grains, explaining avoidance of intergranular fracture as a key creep mechanism, thereby explaining the ductile creep fracture surfaces in the case of the hot-rolled samples

Multi-neutron transfer coupling in sub-barrier 32S+90,96Zr fusion reactions

The role of neutron transfers is investigated in the fusion process below the Coulomb barrier by analyzing 32S+90Zr and 32S+96Zr as benchmark reactions. A full coupled-channel calculation of the fusion excitation functions has been performed for both systems by using multi-neutron transfer coupling for the more neutron-rich reaction. The enhancement of fusion cross sections for 32S+96Zr is well reproduced at sub-barrier energies by NTFus code calculations including the coupling of the neutron-transfer channels following the Zagrebaev semiclassical model. We found similar effects for 40Ca+90Zr and 40Ca+96Zr fusion excitation functions.Comment: Minor corrections, 11 pages, 4 figures, Fusion11 Conference, Saint Malo, France, 2-6 mai 201

Unveiling spatial inequalities: Exploring county-level disaster damages and social vulnerability on public disaster assistance in contiguous US

Understanding the dynamics between public disaster assistance, disaster damages, and social vulnerability at county-level is crucial for designing effective disaster mitigation strategies. This study utilized the Local Bivariate Moran Index (LBMI) and geographically weighted regression (GWR) models to examine spatial patterns and relationships between disaster damages, social vulnerability, and public disaster assistance in contiguous US counties from 2001 to 2021. LBMI results reveal that public disaster assistance has predominantly been directed towards post-disaster recovery efforts, with a particular focus on coastal communities affected by major declared disasters. However, the distributions of public assistance and individual housing assistance, which are the two primary sources of public disaster assistance, do not adequately cover physically and socially vulnerable communities. The distribution of pre-disaster risk mitigation also falls short of sufficiently covering vulnerable communities. Results further indicate the complex interactions between different categories of natural disasters and public assistances. The GWR model results demonstrate spatial variations in predicting each category of public disaster assistance. These findings indicate the need to address disparities in accessing public disaster assistance in the US, and advocate for more equitable disaster mitigation strategies

Combined use of herbivore-induced plant volatiles and sex pheromones for mate location in braconid parasitoids

Herbivore-induced plant volatiles (HIPVs) are important cues for female parasitic wasps to find hosts. Here, we investigated the possibility that HIPVs may also serve parasitoids as cues to locate mates. To test this, the odour preferences of four braconid wasps – the gregarious parasitoid Cotesia glomerata (L.) and the solitary parasitoids Cotesia marginiventris (Cresson), Microplitis rufiventris Kokujev and Microplitis mediator (Haliday) – were studied in olfactometers. Each species showed attraction to pheromones but in somewhat different ways.Males of the two Cotesia species were attracted to virgin females, whereas females of M. rufiventriswere attracted to virginmales. Male and female M.mediator exhibited attraction to both sexes. Importantly, female and male wasps of all four species were strongly attracted by HIPVs, independent of mating status. In most cases, male wasps were also attracted to intact plants. The wasps preferred the combination of HIPVs and pheromones over plant odours alone, except M.mediator, which appears to mainly use HIPVs for mate location. We discuss the ecological contexts in which the combined use of pheromones and HIPVs by parasitoids can be expected. To our knowledge, this is the first study to show that braconid parasitoids use HIPVs and pheromones in combination to locate mates

A possible cooling effect in high temperature superconductors

We show that an adiabatic increase of the supercurrent along a superconductor with lines of nodes of the order parameter on the Fermi surface can result in a cooling effect. The maximum cooling occurs if the supercurrent increases up to its critical value. The effect can also be observed in a mixed state of a bulk sample. An estimate of the energy dissipation shows that substantial cooling can be performed during a reasonable time even in the microkelvin regime.Comment: 5 pages, to appear in Phys. Rev.

Low off-state Leakage Currents in AlGaN/GaN High Electron Mobility Transistors By Employing A Highly Stressed SiNx Surface Passivation Layer

In this study, the impact of the stress in SiNx surface passivation layers on off-state drain and gate leakage currents and off-state breakdown voltage in AlGaN/GaN High Electron Mobility Transistors (HEMTs) is assessed. The SiNx films were deposited at room temperature by inductively coupled plasma chemical vapour deposition (ICP-CVD). Compared to unpassivated devices, the off-state drain and gate leakage currents of AlGaN/GaN HEMTs is increased by up to 2 orders of magnitude for a 200 nm thick SiNx passivation layer with 309 MPa compressive stress. The use of a bilayer SiNx passivation scheme comprising 70 nm SiNx with 309 MPa compressive stress followed by 130 nm SiNx with 880 MPa compressive stress resulted in off-state drain and gate leakage currents reduced by up to 1 order of magnitude when compared to unpassivated devices