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Adenosine is a constitutive cell metabolite with a putative role in protection and regeneration in many tissues. This study was undertaken to determine if adenosine signalling pathways are involved in protection against noise injury. A1 adenosine receptor expression levels were altered in the cochlea exposed to loud sound, suggesting their involvement in the development of noise injury. Adenosine and selective adenosine receptor agonists (CCPA, CGS-21680 and Cl-IB-MECA) were applied to the round window membrane of the cochlea 6 h after noise exposure. Auditory brainstem responses measured 48 h after drug administration demonstrated partial recovery of hearing thresholds (up to 20 dB) in the cochleae treated with adenosine (non-selective adenosine receptor agonist) or CCPA (selective A1 adenosine receptor agonist). In contrast, the selective A2A adenosine receptor agonist CGS-21680 and A3 adenosine receptor agonist Cl-IB-MECA did not protect the cochlea from hearing loss. Sound-evoked cochlear potentials in control rats exposed to ambient noise were minimally altered by local administration of the adenosine receptor agonists used in the noise study. Free radical generation in the cochlea exposed to noise was reduced by administration of adenosine and CCPA. This study pinpoints A1 adenosine receptors as attractive targets for pharmacological interventions to reduce noise-induced cochlear injury after exposure.

Study objectives To determine whether, in patients with bilateral pleural effusions, the main cellular and biochemical features of the pleural fluid on the right side differ from or correlate with those on the left side. We examined lactate dehydrogenase (LDH), glucose, and total protein (TP) levels, RBC count, nucleated cell count (NCC), and differential cell count. Patients and methods Twenty-seven patients with bilateral pleural effusions, including 13 patients with effusions after coronary artery bypass graft surgery, 12 patients with congestive heart failure, 1 patient with malignant pericarditis, and 1 patient with renal failure, were studied retrospectively. Results The right-sided and the left-sided pleural effusions did not differ in the mean TP (p = 0.38), glucose (p = 0.31), and LDH (p = 0.39) levels, RBC count (p = 0.31), NCC (p = 0.96), and the percentage of neutrophils (p = 0.22), lymphocytes (p = 0.73), mononuclear cells (MNCs) [p = 0.49], and eosinophils (p = 0.65). The bias ± precision was 0.1 ± 0.64 g/dL for TP, − 2.7 ± 23 mg/dL for glucose, 41 ± 362 IU/L for LDH, 6,100 ± 62,900 cells/μL for RBC count, − 36 ± 1,043 cells/μL for NCC, − 2.9 ± 11.6% for the percentage of neutrophils, 1.15 ± 17% for the percentage of lymphocytes, 2.3 ± 17% for the percentage of the MNCs, and − 0.15 ± 5.4% for the percentage of eosinophils. Moreover, there was a close correlation between the right-sided and the left-sided pleural effusions concerning TP level ( r = 0.85, p r = 0.78, p r = 0.71, p r = 0.66, p r = 0.60, p = 0.001), and the percentage of neutrophils ( r = 0.77, p r = 0.77, p r = 0.74, p r = 0.84, p Conclusion Since the pleural fluid findings tend to be similar in both sides of patients with bilateral pleural effusion, we suggest that diagnostic thoracentesis may not need to be performed on both sides, unless there is a specific clinical indication.

Teke, Ali (Balikesir Author), We report on the operation and non-linear dynamics of a hot electron device that emits light with wavelength tunability, The device consists of p-GaAs/n-Ga-1 -xAlxAs heterojunction containing an inversion layer on the p-side, and GaAs quantum wells on the n-side. It is referred to as HELLISH-2 (Hot Electron Light Emitting and Lasing in Semiconductor Heterostructure Type 2). The device utilises hot electron longitudinal transport and the light emission is independent of the polarity of applied voltage. The wavelength of the emitted light can be tuned with applied bias from 1.50 to 1.61 eV. The operation of the device requires only two diffused in point contacts. Theoretical modelling of the device operation has been carried out and compared with the experimental results.

A novel hot electron light-emitting device is proposed which operates by the application of longitudinal electric field, i.e. in the plane of the GaAs quantum wells, which are placed next to the junction plane of an n-Ga1-xAlxAs--p-GaAs heterostructure. Application of high electric fields results in the transfer of hot electrons via tunnelling and thermionic emission, from the quantum well in the depletion region, into the GaAs inversion layer. The hot holes in the p-GaAs, initially away from the junction, then diffuse towards the junction plane to recombine with the excess hot electrons, giving rise to electroluminescence (EL) which is representative of the GaAs band-to-band emission. As the applied field is increased, a high-energy tail in the EL spectrum develops, and, photons with energies greater than the el-hhl transition energy in the quantum well are absorbed and re-emitted by the quantum well. Thus a second peak develops in the EL spectra which becomes stronger with increasing applied electric field. The device has been theoretically modelled, by solving Schrodinger and Poisson's equations self-consistently, to understand the processes leading to EL emission in the various channels.

A novel light emitting device is proposed and demonstrated experimentally. The device consists of a GaAs quantum well placed on the n-side of the depletion region of a Ga1-xAlxAs p-n junction. Electric fields are applied parallel to the layers between two point contacts. The operation of the device is based upon the accumulation, in the quantum well, of excess hot electrons injected from the n region of the barrier via tunnelling and thermionic emission. Negative charge accumulation in the depletion region changes the potential profile, and therefore leads to a decrease in the depletion width and the potential barrier in the p-side of the junction. Hot holes then diffuse into the quantum well to recombine with the electrons. Emitted light intensity is independent of the polarity of the applied voltage. Theoretical modelling of the device is carried out by solving Schrodinger's and Poisson's equations self-consistently by incorporating tunnelling, and diffusion dynamics of the hot carriers.

Applying orthogonal in-plane electric and magnetic fields in a 2D system leads to the development of a Hall voltage across the width of the quantum well when the cyclotron orbit is greater than the well width. Tang and Butcher [1] have calculated the developed Hall voltage for a parabolic quantum well where they find that the Hall voltage is dependent on the frequency associated with the harmonic potential in the well. The limitation of this model is that it does not enable one to determine the well width dependence of the Hall Voltage, nor is it a particularly good model for a quantum well. It is also difficult to compare their model with the bulk result which would apply at large well widths. In this work we present a model calculation which considers a square quantum well and hence is able to predict the well width dependence of the Hall Voltage and compare the large well width case to the bulk result. An electro-optic probing method previously used to measure bulk Hall voltages [2] is shown to be capable of measuring the Hall 'voltage across a quantum well, and therefore can be used to confirm the prediction of the model presented here.

The effect of phonons in non-thermodynamic equilibrium (hot-phonons) on steady-state transport in degenerate bulk and two-dimensional (2D) semiconductor structures is studied. The phonon-drift effects are taken to be negligible, and, the formulation is confined to electrons in a single parabolic band interacting with a non-drifted population of polar-optic phonons, restricted to interface modes in the 2D case. Hot phonons in bulk semiconductors lead not only to a decrease in the energy relaxation rate, but, also, to a decrease in the mobility as the carrier concentration n3D is increased. Hot phonons in 2D systems, on the other hand, cause the energy relaxation rate and mobility to go through a minima as the electron concentration n2D is increased. The electron drift velocity, contrary to the bulk case, is seen to increase with n2D for n2D > 1012cm−2, and reflects the difference in the nature of electron density of states in the two cases.

We report experimental observations concerning high field parallel transport in GaAs/GaAlAs quantum-well structures comparing degenerate and non-degenerate material. Hot electron photoluminescence measurements show hot-phonon reduction of the energy relaxation rates in degenerate material as compared with that in non-degenerate material in agreement with a simple model of transport involving hot phonon effects. The latter predicts a reduction in drift velocity at high fields compared with that in bulk material and this is observed in our specimens. Hot phonons are shown to inhibit instabilities. Non degenerate samples exhibit current instabilities much more readily than degenerate material. In the latter, the hot phonon reduction in drift velocity will tend to inhibit NDR via real space transfer or via intervalley transfer.

The E1 critical-point energies are calculated for the ternary alloys Gax- In1-xP, GaxIn1-xAs, GaAs1-xPx and InAs1-xPx in coherent-potential approximation using tight-binding Hamiltonian and neglecting spin-orbit effects. Good agreement, to within a few percent, is obtained between the calculated values of the E1 energy gap and the corresponding experimental values, for all the ternary systems studied here.

Scattering and well-width non-uniformities in double-barrier single quantum well structures have been modelled by a level-broadening Γ i of the energy state in the well in an approach which allows us to explore the whole regime between coherent and sequential tunneling. In addition to causing a reduction and broadening of the transmission resonance, and, consequently, a fall in the peak current density, level-broadening Γ i introduces losses in the probability current. The implication of the inevitable presence of level-broadening on tunnelling characteristics of various heterostructures is discussed in terms of the structural parameters, e.g., height and width of the potential barrier and the conduction-band offset between the contact layer and well.

It is shown that electronic X-ray Raman scattering in metals can be suppressed due to the intermediate state interaction between the deep hole and the Fermi sea of electrons.

Experimentally observed phonon softening of the 520 cm-1 Raman line in ultra-heavily doped n-Si is attributed to the electron-phonon self-energy effects as well as change in lattice force constants of the alloy system.