In order to evaluate the effectiveness of CdTe surface passivating layers, HgCdTe photoconductors with and without CdTe sidewall passivation were fabricated. As expected, photoconductors with CdTe ...sidewall passivation demonstrated significantly higher responsivity in comparison with those without sidewall passivation, indicating the effectiveness of molecular-beam epitaxially (MBE)-grown CdTe as a passivation layer in reducing surface recombination velocity. Characterization of the responsivity differences between photoconductors with and without sidewall CdTe passivation offers a potential method for measuring the interface/surface recombination velocity. This has been demonstrated in this paper by extracting the value of the surface recombination velocity using the Synopsys Sentaurus commercial modeling package to fit experimental responsivity data for fully and partially passivated devices.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Managing manure in reduced tillage and forage systems presents challenges, as incorporation by tillage is not compatible. Surface-applied manure that is not quickly incorporated into soil provides ...inefficient delivery of manure nutrients to crops due to environmental losses through ammonia (NH3) volatilization and nutrient losses in runoff, and serves as a major source of nuisance odors. An array of technologies now exist to facilitate the incorporation of liquid manures into soil with restricted or minor soil disturbance, some of which are new: shallow disk injection; chisel injection; aeration infiltration; pressure injection. Surface banding of manure in forages decreases NH3 emissions relative to surface broadcasting, as the canopy can decrease wind speed over the manure, but greater reductions can be achieved with manure injection. Soil aeration is intended to hasten manure infiltration, but its benefits are not consistent and may be related to factors such as soil drainage characteristics. Work remains to be done on refining its method of use and timing relative to manure application, which may improve its effectiveness. Placing manure under the soil surface by injection offers much promise to improve N use efficiency through less NH3 volatilization, reduced odors and decreased nutrient losses in runoff, relative to surface application. We identified significant gaps in our knowledge as many of these technologies are relatively new, and this should help target future research efforts including environmental, agronomic, and economic assessments.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The electrical properties of semiconductor materials have conventionally been extracted via Hall measurements performed at a single magnetic field. When applied to a semiconductor such as HgCdTe with ...mixed conduction characteristics, the values obtained from the Hall measurement represent only an averaged contribution of all carriers present in the sample. In this study, the transport properties of a liquid-phase epitaxially (LPE) grown p-type HgCdTe were determined. Variable magnetic field and temperature Hall and resistivity measurements were employed in conjunction with the improved-quantitative mobility spectrum analysis (iQMSA) algorithm to extract the concentrations and mobilities of all carriers present in the material. A comparison study was made between a van der Pauw Greek cross and a standard Hall bar structure on the same material. A disparity in the transport property of the sample was observed when both structures were measured within a few days of each other. Through iQMSA analysis, the discrepancy is seen to be attributed to the formation of an n-type skin inversion layer within a week after processing.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Beta-adrenergic receptors (β-ARs) critically modulate long-lasting synaptic plasticity and long-term memory storage in the mammalian brain. Synaptic plasticity is widely believed to mediate memory ...storage at the cellular level. Long-term potentiation (LTP) is one type of synaptic plasticity that has been linked to memory storage. Activation of β-ARs can enhance LTP and facilitate long-term memory storage. Interestingly, many of the molecular signaling pathways that are critical for β-adrenergic modulation of LTP mirror those required for the persistence of memory. In this article, we review the roles of signaling cascades and translation regulation in enabling β-ARs to control expression of long-lasting LTP in the rodent hippocampus. These include the cyclic-AMP/protein kinase-A (cAMP–PKA) and extracellular signal-regulated protein kinase cascades, two key pathways known to link transmitter receptors with translation regulation. Future research directions are discussed, with emphasis on defining the roles of signaling complexes (e.g. PSD-95) and glutamatergic receptors in controlling the efficacy of β-AR modulation of LTP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The semiconductor-passivating layer interfaces, as well as their dielectric properties, play important and very often dominant roles in determining HgCdTe device performance. In this work, ...photoconductors were fabricated on p-type mid-wave infrared Hg 1-x Cd x Te material using molecular beam epitaxy (MBE) grown CdTe film as the passivation layer. In order to emphasize the importance of the CdTe passivating layer, HgCdTe photoconductors with and without the sidewall CdTe passivation were fabricated. The photoconductor with its sidewalls passivated shows significantly higher responsivity than the one without sidewall passivation. Conductance-voltage characteristics of capacitor using CdTe between HgCdTe and metal contacts were made in studying insulating property of the passivation film. Scanning electron microscopy (SEM) micrographs and X-ray diffraction (XRD) spectra were included in order to investigate the structural properties of the CdTe passivation film.
Extrinsic p-type doping of Mercury Cadmium Telluride (HgCdTe) epilayers grown by Molecular Beam Epitaxy (MBE) was carried out with an arsenic (As) cracker cell. As-grown samples were characterised ...via Fourier Transform Infrared Transmission Spectrometry (FTIR) and Secondary Ion Mass Spectrometry (SIMS). A preliminary study on various activation annealing techniques is made, where HgCdTe layers were annealed under Hg overpressures in a closed tube furnace at varying temperatures to either activate arsenic and/or, to eliminate Hg vacancies. Variable field magneto-transport measurements coupled with the quantitative mobility spectrum analysis (QMSA) were then utilised to study the Hall effect characteristics of the annealed material.
Long-term potentiation (LTP) in the hippocampus is thought to contribute to memory formation. In the Ca1 region, LTP requires the NMDA (N-methyl-D-aspartate) receptor-dependent influx of Ca2+ and ...activation of serine and threonine protein kinases. Because of the high amount of protein tyrosine kinases in hippocampus and cerebellum, two regions implicated in learning and memory, we examined the possible additional requirement of tyrosine kinase activity in LTP. We first examined the specificity in brain of five inhibitors of tyrosine kinase and found that two of them, lavendustin A and genistein, showed substantially greater specificity for tyrosine kinase from hippocampus than for three serine-threonine kinases: protein kinase A, protein kinase C, and Ca2+/calmodulin kinase II. Lavendustin A and genistein selectively blocked the induction of LTP when applied in the bath or injected into the postsynaptic cell. By contrast, the inhibitors had no effect on the established LTP, on normal synaptic transmission, or on the neurotransmitter actions attributable to the actions of protein kinase A or protein kinase C. These data suggest that tyrosine kinase activity could be required postsynaptically for long-term synaptic plasticity in the hippocampus. As Ca2+ calmodulin kinase II or protein kinase C seem also to be required, the tyrosine kinases could participate postsynaptically in a kinase network together with serine and threonine kinases.
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