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A dual-functional ultraviolet (UV) photodetector with a large UV-to-visible rejection ratio is presented, in which interdigitated finger-type two-dimensional graphene electrodes are introduced to an AlGaN/GaN heterostructure. Two photocurrent generation mechanisms of photovoltaic and photoconductive dominances coexist in the device. The dominance of the mechanisms changes with the induced bias voltage. Below a threshold voltage, the device showed fairly low responsivities but fast response times, as well as a constant photocurrent against the induced bias. However, the opposite characteristics appeared with high bias voltage. Specifically, above the threshold voltage, the device showed high responsivities with additional gain, but slow rise and recovery times. For instance, the responsivity of 10.9 A/W was observed with the gain of 760 at the induced bias voltage of 5 V. This unique multifunctionality enabled by the combination of an AlGaN/GaN heterostructure with graphene electrodes facilitates the development of a single device that can achieve multiple purposes of photodetection. [ABSTRACT FROM AUTHOR]

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GaInN/GaN multiple-quantum-well light-emitting diodes (LEDs) with 0.4 μm-thick AlGaN cladding layers and two quantum wells (QWs), designed for investigating the origin of efficiency droop, are demonstrated to have a lower efficiency droop than typical GaInN/GaN LEDs with 5 QWs. Considering the much less electron leakage over the active region, and the larger carrier density due to the smaller active volume of the LED with AlGaN cladding layers than those of the typical LED, it is suggested that the dominant mechanism responsible for the efficiency droop is electron leakage rather than the Auger recombination which scales with the cubic power of the carrier density. [ABSTRACT FROM AUTHOR]

To harness the full spectrum of solar energy, optical reflections at the surface of a solar photovoltaic cell must be reduced as much as possible over the relevant solar spectral range and over a wide range of incident angles. The development of antireflection coatings embodying omni-directionality over a wide range of wavelengths is challenging. Recently, nanoporous films, fabricated by oblique-angle deposition and having tailored- and very low-refractive index properties, have been demonstrated. Tailorability of the refractive index and the ability to realize films with a very low-refractive index are properties critical in the performance of broadband, omnidirectional antireflection coatings. As such, nanoporous materials are ideally suited for developing near-perfect antireflection coatings. Here, we discuss multilayer antireflection coatings with near-perfect transmittance over the spectral range of 400−2000 nm and over widely varying angles of acceptance, 0−90°. The calculated solar optical-to-electrical efficiency enhancement that can be attained with nanoporous multilayer coatings over single-layer quarter-wave films is 18%, making these coatings highly attractive for solar cell applications. [ABSTRACT FROM AUTHOR]

Newly developed software, NoteView, is used to analyse the fundamental frequency (F0) and categorical as well as microtonal pitch from audio recordings of music performances from a single line (monophonic) instrument. The code is based on the SWIPE algorithm developed by Camacho and Harris. The features of the interface are described and a comparison of two performances of a familiar piece played by a professional French horn player is used as an example for the purpose of investigating the pitch stability of the two renditions. Results produced by NoteView indicate that pitch pairs across the two performances differed by a mean of 7 cents, and that within-note standard deviation was typically 6 cents. These results are examined using the various customisable views and statistics returned by the software. Some of the features and limitations of NoteView are discussed. The software is currently implemented in Matlab and is freely available from the UNSW Empirical Musicology web site http://empa.arts.unsw.edu.au/research-and-creative-practice/research-projects/ empirical-musicology/. [ABSTRACT FROM AUTHOR]

Abrasive waterjets (AWJs) have proven to be a versatile tool for precision machining of a variety of materials and are applicable to virtually any material; there is no heat-affected zone, no tooling, fast turnaround, and is cost-effective for large and small lot sizes. Nevertheless, damage to delicate material may occur during the initial piercing stage. The large buildup of piercing pressure ( pp) inside blind holes is responsible for the damage. Laboratory results show that pp decreases with the hole depth. At 345 MPa, waterjet-induced pp in an AWJ-pierced blind hole was measured and extrapolated to be about 180 MPa at the target surface. Such a large pp exceeds the ultimate strength of many delicate materials such as laminates, composites, glass, and other brittle materials. We have discovered that the phase change of the working fluid of liquefied nitrogen (LN2) in an abrasive cryogenic jet (ACJ) is an effective means to mitigate piercing damage. Most of the LN2 evaporates before entering the blind hole, significantly reducing the piercing pressure. This paper investigates the causes and extent of piercing damage induced by AWJs. Understanding such causes has led to the development of a cost-effective flash abrasive waterjet (FAWJ) to emulate the phase change of the ACJ for mitigating piercing damage. The mechanisms leading to the mitigation of piercing damage by the FAWJ are described qualitatively and quantitatively. Comparison of the visual results of holes pierced in several delicate materials with AWJs and FAWJs is presented to correlate the extent and the mitigation of damage with the piercing pressure. [ABSTRACT FROM AUTHOR]

A systematic study is performed to optimize aluminum nitride (AlN) epilayers grown on (0001) sapphire by metal-organic vapor-phase epitaxy. Specifically, the impact of the AlN nucleation conditions on the crystalline quality and surface morphology of AlN epilayers is studied. Atomic force microscopy (AFM) and x-ray diffraction (XRD) results reveal that the nucleation layer plays a critical role in the growth of subsequent layers. The magnitude of the TMAl flow of AlN nucleation layer is found to have a strong effect on the crystalline quality and surface morphology of the high-temperature (HT) AlN epilayer. A simple Al adatom-diffusion-enhancement model is presented to explain the strong dependence of the crystalline quality and surface morphology on TMAl flow. Furthermore, ammonia flow, nucleation temperature, and growth time of the AlN nucleation layer are found to affect the surface morphology and the crystalline quality as well. A trade-off is found between surface morphology and crystalline quality; that is, we do not obtain the best surface morphology and the highest crystalline quality for the same growth parameters. For optimized AlN nucleation layers and HT AlN epilayers, a clear and continuously linear step-flow pattern with saw-tooth shaped terrace edges is found by AFM on AlN epilayers. Triple-axis x-ray rocking curves show a full-width at half-maximum (FWHM) of 11.5 arcsec and 14.5 arcsec for the (002) and (004) reflection, respectively. KOH etching reveals an etch-pit density (EPD) of 2 x 107 cm-2, as deduced from AFM measurements. [ABSTRACT FROM AUTHOR]

In 1880, by studying light passing through Earth's atmosphere, Lord Rayleigh mathematically demonstrated that graded-refractive-index layers have broadband antireflection characteristics. Graded-index coatings with different index profiles have been investigated for broadband antireflection properties, particularly with air as the ambient medium. However, because of the unavailability of optical materials with very low refractive indices that closely match the refractive index of air, such broadband antireflection coatings have not been realizable. Here we report the fabrication of TiO2 and SiO2 graded-index films deposited by oblique-angle deposition, and, for the first time, we demonstrate their potential for antireflection coatings by virtually eliminating Fresnel reflection from an AlN–air interface over a broad range of wavelengths. This is achieved by controlling the refractive index of the TiO2 and SiO2 nanorod layers, down to a minimum value of n = 1.05 in the case of the latter, the lowest value so far reported. [ABSTRACT FROM AUTHOR]

Glancing angle deposition by utilizing an ion beam sputter process and a controlled substrate rotation is used to deposit silicon nanostructures with different structure varieties. The structures are grown on seeded and plain [100] silicon substrates at room temperature. The ratio of deposition rate to substrate angular frequency and the substrate surface properties determine the nanostructure geometry, size and assembly. [ABSTRACT FROM AUTHOR]

Molybdenum single layers were grown by ion beam sputter deposition onto [001] Si substrates. Argon or xenon was used as sputter gas. The layer growth was monitored by real-time in situ spectroscopic ellipsometry in the visible spectral region. A volume phase transition from amorphous to polycrystalline molybdenum layer growth was observed during the deposition process. The time regime of the phase transition as well as the layer thickness at which the phase transition occurs, depends on the sputter regime, especially on sputter species and deposition-pressure range. The thermodynamic approach of energy minimisation is discussed as the driving force for the Mo phase transition. A moderate backscattered particle bombardment of the growing molybdenum film provides the activation energy for the recrystallisation process. A self-diffusion-like process is made responsible for atomic rearrangement of the entire as-deposited thin-film volume. The molybdenum phase transition is connected to thin-film densification and therefore volume contraction. [ABSTRACT FROM AUTHOR]

The versatility of the laser beam cladding process as a means of localized surface treatment is highlighted in this article with an emphasis on applications in the field of repair and regeneration. A newly developed cladding technology using low power Nd:YAG lasers is also introduced. Small dimensions and minimal heat input allow high precision cladding. Short interaction times and good control of the process enable the generation of graded composite coatings. Application examples in the field of regeneration of components are given. An industrial case study presents the CO2 laser repair of large engine components. [ABSTRACT FROM AUTHOR]

The resolution of the Capacitance-Voltage (C-V) technique on semiconductors with quantum-confinement is shown to be given by the spatial extent of the wave function which represents the electron (hole) system. The classical Debye-length-broadening of the C-V technique is shown to be invalid in the quantum-confinement regime. Capacitance-voltage profiles on δ-doped GaAs exhibit a full-width at half-maximum of 20 and 40Å for p-type and n-type impurities, respectively. The experimental C-V profiles on δ-doped GaAs agree with theory and demonstrate that impurities are spatially localized on the length scale of the lattice constant. [ABSTRACT FROM AUTHOR]

Spatial localization and diffusion of atomic Si is studied in σ-doped GaAs by employing capacitance-voltage (CV) measurements and rapid thermal annealing. It is found that diffusion and segregation are irrelevant in σ-doped GaAs grown at temperatures below 550° C. Combination of rapid thermal annealing and capacitance-voltage profiling is a novel method which is most sensitive to diffusion and it is shown that this method is able to detect diffusion on a length scale of 10Å. CV-profile widths broaden from⪯40Å to 137Å upon rapid thermal annealing at 1000° C for 5 sec. The diffusion coefficient and the activation energy of atomic Si-diffusion in GaAs are determined to be D = 4 × 10 cm/s and E = 2.45 eV, respectively. The basic theory of CV-measurements on a quantum-mechanical electron system is developed. [ABSTRACT FROM AUTHOR]

The pediatric eye-tumor retinoblastoma is widely held as a paradigm of human cancer genetics and has been a model system for both the two-hit hypothesis of dominantly inherited cancer as well as for the concept of tumor-specific loss of constitutional heterozygosity to achieve expression of the tumorigenic phenotype. Familial retinoblastoma is usually inherited as an autosomal dominant disease with high penetrance and expressivity. In a small but significant number of families, however, retinoblastoma is inherited with greatly reduced penetrance and expressivity. In these families, retinoblastoma tumors occur relatively late, are often unilateral, and unaffected carriers may exist. We have identified a mutation in such a family that exhibited extremely low penetrance and expressivity. This mutation appeared to affect splicing of the mutant allele such that both a normal length RB1 mRNA and a truncated RB1 mRNA were expressed from the same allele. [ABSTRACT FROM AUTHOR]

Armco iron samples were surface nitrided by irradiating them with pulses of an excimer laser in a nitrogen atmosphere. The resulting nitrogen depth profiles measured by Resonant Nuclear Reaction Analysis (RNRA) and the phase formation determined by Conversion Electron Mössbauer Spectroscopy (CEMS) were investigated as functions of energy density and the number of pulses. The nitrogen content of the samples was found to be independent of the number of pulses in a layer of 50 nm from the surface and to increase in depths exceeding 150 nm. The phase composition did not change with the number of pulses. The nitrogen content can be related to an enhanced nitrogen solubility based on high temperatures and high pressures due to the laser-induced plasma above the sample. With increasing pulse energy density, the phase composition changes towards phases with higher nitrogen contents. Nitrogen diffusion seems to be the limiting factor for the nitriding process. [ABSTRACT FROM AUTHOR]

Histamine (5×10 to 10M) depressed the spontaneous motility of the isolated rat uterus in a dose-dependent manner. Under these conditions uterine cyclic AMP was raised up to 92%. Both effects, uterine relaxation and cyclic AMP accumulation after 2 min could be inhibited dose dependently by the H-antihistaminic compound metiamide (1.7×10 M to 1.7×10 M). By contrast, the H-antagonist pheniramin (4.4×10 M) was ineffective. It was concluded that the histamine-induced inhibition of rat uterine motility is mediated by cyclic AMP which is formed in response to stimulation of H-histaminergic receptors. [ABSTRACT FROM AUTHOR]

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Copyright of Somnologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tone and motility of the isolated guinea pig ileum were increased by irradiation with a dose of 10 krd. The maximal effect corresponds to that induced by 0.001 µg/ml acetylcholine or 0.3 µg/ml nicotine. The pharmacological analysis of this effect performed with acetylcholine and nicotine and several blocking agents including hexamethonium, atropine, tetrodotoxin, diphenhydramine, and verapamil suggests that radiation acts on the postganglionic parasympathetic neuron and the neuromuscular synapse. The mechanism of radiation is likely to consist of both an increased release of acetylcholine from the postganglionic neuron and a sensibilization of the cholinergic receptor site at the smooth muscle cell. The latter effect is thought to result from an increased contractile action induced by acetylcholine or nicotine in the irradiated ileal smooth muscle. [ABSTRACT FROM AUTHOR]

Investigating the relationship between the breakdown voltage and the capacitance of GaInN light-emitting diodes (LEDs), we find that a lower capacitance due to weaker internal electric field in depletion region or wider depletion width at the pn junction results in lower reverse leakage current and thus larger breakdown voltage. The measured breakdown voltage and capacitance of LEDs show a strong correlation, opening a nondestructive and non-intrusive way to estimate the breakdown voltage of an LED based on the capacitance-voltage measurement. [ABSTRACT FROM AUTHOR]

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Copyright of Zeitschrift Für Die Gesamte Experimentelle Medizin Einschließlich Experimentelle Chirurgie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Albrecht von Graefes Archiv für Klinische und Experimentelle Ophthalmologie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pflüger's Archiv Für Die Gesamte Physiologie Des Menschen Und Der Tiere is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pflüger's Archiv Für Die Gesamte Physiologie Des Menschen Und Der Tiere is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pflüger's Archiv Für Die Gesamte Physiologie Des Menschen Und Der Tiere is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pflüger's Archiv Für Die Gesamte Physiologie Des Menschen Und Der Tiere is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pflüger's Archiv Für Die Gesamte Physiologie Des Menschen Und Der Tiere is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

1. Relations of oxygen pressure (between 0 and 10 atm.) to simultaneously measured heights of b-wave and oxygen consumption have been studied in the isolated amphibian eye. 2. It was intended to ascertain, if there is-within the cell-a mechanism enabling it to hold its own O consumption and its biological function on a constant level regardless of changes in surrounding O pressure. 3. It was found that, within the range of oxygen deficiency, bioelectric activity and O consumption of isolated cells change proportionally to O pressure. 4. High oxygen pressure damps the bioelectric activity but has no hindering effect on O consumption. Therefore dissociation of bioelectric activity and O uptake arises, which means a lowering of efficiency. 5. There is no experimental evidence of a mechanism within the single cell for smoothing out the effects of O pressure changes. On the whole, the isolated cell reacts in view of O consumption and bioelectric activity like a pure physicochemical system. Therefore it seems to be reasonable to describe the cell-behaviour towards oxygen by means of the law of mass action or even by flux equations as Thunberg and Lund have tried many years ago. 6. In the whole animal the regulatable blood flow screens the individual cells from outside changes of oxygen pressure within wide limits. [ABSTRACT FROM AUTHOR]

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Zn-doped InP and GaInPAs layers were grown by OrganoMetallic Vapor-Phase Epitaxy (OMVPE). The epitaxial films consist of a primary GaInPAs/InP epitaxial layer and a secondary InP/GaInAs epitaxial layer. We present evidence that the redistribution of Zn acceptors in the primary epitaxial layer is strongly influenced by the Zn doping concentration in the secondary epitaxial layer. Rapid redistribution of Zn acceptors in the primary epitaxial layer occurs if the Zn doping concentration in the secondary epitaxial layer exceeds a critical concentration of N≅3×10cm. The influence of the growth temperature on this effect is also presented. [ABSTRACT FROM AUTHOR]

Phospholamban, a sarcoplasmic reticulum phosphoprotein, is present in the hearts of mammalian, avian, amphibian, and fish species. Phylogenetic changes are indicated by marked differences among species in cardiac phospholamban content and by the absence of Ca/calmodulin-dependent phospholamban phosphorylation at an early developmental stage. [ABSTRACT FROM AUTHOR]

The article comments on the use of electron-beam pumping in an alternative design of semiconductor ultra violet (UV) emitter to accomplish 240 nm emission with an efficiency of 40 percent more than an order of magnitude, at an optical power of 100 mW. The study was made by Japanese researcher T. Oto and others. The researchers have stated that the strong carrier confinement provided by high-quality AlGaN/AlN quantum wells is the reason for the high efficiency of their UV emitter.