Changes in oxygen tension in tumor during induced hyperglycemia

It is shown that tumour PO2 falls by the factor of 2 or 3 at the 120-150 min i/v glucose infusion (80 mg.kg-1.min-1) to the rats bearing Guerin carcinoma. This is due to a decrease oxygen transport into the tumour induced by inhibition of local blood flow.     

Band-tail model and temperature-induced blue-shift in photoluminescence spectra of InxGa1-xN grown on sapphire

A band-tail model of inhomogeneously broadened radiative recombination is presented and applied to interpret experimental data on photoluminescence of various bulk and quantum-well epitaxial InGaN/GaN structures grown by MOCVD. The temperature dependence of the spectral peak position is analyzed according to the model, explaining the anomalous temperature-induced blue spectral shift. Significant differences are observed between epilayers grown on sapphire substrates and on GaN substrates prepared by the sublimation method. No apparent evidence of band tails in homoepitaxial structures indicates their higher crystalline quality.     

GDNF is abundant in the adult rat gut

This study was performed to assess the value TTC assay in the diagnosis of biomaterial-associated infections. In this assay, soluble colourless TTC is reduced to insoluble red formazan by electron transfer associated with active oxidative bacterial metabolism and is precipitated intracellularly. Microbial adhesion and biofilm formation on the surface of medical prosthetic devices (vesicular and urinary catheters) made of various polymers (PTFE, H-PE, PCW, SL), were determined. The microorganisms which are most often isolated in medical device-associated infections: S. aureus, S. epidermidis, E. faecalis, E. coli, P. vulgaris, P. aeruginosa, C. albicans, were included into the study. The obtained results indicate that the assay using TTC as a metabolic indicator of bacterial biofilm presence, is technically simple to conduct with minimal setup time. Even when classical cultures yielded no bacterial growth, TTC assessments demonstrated bacterial biofilms. TTC assay could be recommended as a quick routine method for confirmation of biomaterial device-associated infection.     

High-power, spectrally coherent array of monolithic flaredamplifier-master oscillator power amplifiers (MFA-MOPAs)

A monolithically integrated array of InGaAs/AlGaAs flared amplifiers driven by a single DBR laser through a power splitter network is described. This architecture is capable of providing single-mode, diffraction-limited performance from each emitter and is scalable to unprecedented power levels. Over 20 W of pulsed, spectrally coherent emission is generated at 955 nm from a 4-element array, and 39 W is obtained from an 8-element array     

Increased active stress generation of denervated rat intestinal smooth muscle: functional analysis of muscarinic receptor population

The effects of denervation on the active stress production by the longitudinal muscle (LM) layer of rat jejunum were examined. Extrinsic and myenteric denervation of a segment of rat jejunum was accomplished by the serosal application of the cationic surfactant benzyldimethyltetradecylammonium chloride (BAC). Isolated muscle contraction experiments revealed that the LM of the jejunum taken from rats treated with BAC 15 days before developed significantly increased active stress in response to bethanechol and carbachol, but not in response to potassium chloride. No change in -log EC50 values of any of the agonists was observed in the denervated LM layer, although a significant increase in the slope of the carbachol and bethanechol concentration-response curves was observed in the denervated LM. Schild analysis of several muscarinic antagonists revealed a 3-fold increase in the apparent dissociation constant of the M2 antagonist methoctramine in BAC-treated LM. These results suggest that the increased responsiveness of the denervated LM may originate in the muscarinic receptor population of the myocytes.     

Linewidth broadening factor in semiconductor lasers--An overview

The objective of this paper is to present an overview of topics related to one of the fundamental parameters for semiconductor lasers-the linewidth broadening factor α that describes the coupling between carrier-concentration-induced variations of real and imaginary parts of susceptibility. After introducing the definition of α and discussing its dependence on carrier concentration, photon energy, and temperature, we give a short historical summary on how the concept of α evolved over the past two decades. This is followed by a discussion of α dependence on device structure in gain-guided and subdimensional lasers (quantum wells and quantum wires). The bulk of the paper is devoted to a detailed review of laser properties influenced by α and of associated methods of estimating the value of α. Results of measurements reported to date are collected and the most reliable methods are indicated.     

Evaluation of thermal imaging system and thermal radiation detector for real-time condition monitoring of high power frequency converters

We have carried out at laboratory test to study the feasibility of using thermal radiation detectors for online thermal monitoring of electrical systems in wind
turbines. A 25 kW frequency converter is instrumented with a thermal camera, operating in the 8–14 lm wavelength range, and a single-pixel thermopile sensor, operating in the 4–8 lm wavelength range, to monitor the temperature development of the power electronics under various load sequences. Both systems performed satisfactorily with insignificant temperature deviations when compared to data from calibrated point contact sensor. With spatial averaging over a 7 mm 9 7 mm for the camera and temporal averaging over 60 s for the thermopile sensor, we reduce the root mean square noise to 45 mK
and 68 mK respectively. The low cost and simple operation of the thermopile sensor make it very attractive for condition monitoring applications, whereas the attractive feature of the camera is the possibility of multi-point or distributed temperature measurements.     

Hydrogen ion concentration in tumor issue and artificial hyperglycemia

A series of articles concerned with determination of pH in the tumour and with studies of pH changes under induced hyperglycemia are reviewed. Based on the available data the following conclusions are drawn: pH in the tumour tissue is lower than in the initial normal or surrounding tissues by 0.5 units on the average; the optimal pH value is more acidic; alkalosis in the tumour-bearing organism is a hypercompensatory reaction of the host as a result of advanced tumour in which pH is dropped; the induced hyperglycemia promotes a pronounced decrease of pH in the tumour, pH of the normal tissues being unchanged; the possibility to decrease pH in the tumour should be taken into account when developing new methods of the antitumour therapy.     

Electronically tunable, 1-W CW, near-diffraction-limited monolithicflared amplifier-master oscillator power amplifier (MFA-MOPA)

An electronically tunable monolithic flared amplifier master oscillator power amplifier structure is described. This device is composed of a DBR laser tunable by free-carrier injection integrated with a flared amplifier, and generates 1-W CW of near-diffraction-limited, single mode power at λ~980 mm, while allowing wavelength tuning over a 6-Å range using a tuning current of 30 mA. This device is useful in applications requiring high power, high beam quality, and precise wavelength control simultaneously such as in frequency doubling     

InGaN-based ultraviolet emitting heterostructures with quaternary AlInGaN barriers

Nitride-based ultraviolet (UV) heterostructures with InGaN quantum wells and AlInGaN barrier layers have been grown by metal-organic chemical vapor deposition on sapphire substrates. The emission band was at 3.307 eV (375 nm) at room temperature (RT) and its full-width at half-maximum was /spl sim/82meV. In addition to the UV band, some blue emission admixture was found in a single-quantum-well (SQW) structure, which the authors attribute to recombination of injected electrons that are not captured into the SQW and enter the p-side of the structure. The authors demonstrate a significant advantage in utilizing multiple-quantum-well (MQW) structures that provide a more effective capture of injected carriers into wells and predominance of UV emission. Temperature-sensitive competition between two emission mechanisms in MQW structures has been observed. Below /spl sim/170 K, the blue impurity-related emission dominated. In the 170-190 K range, an anomalous temperature-induced "blue jump" by over /spl sim/340 meV to UV region occurred, with UV emission dominating above 190 K.