Inherent emf relaxation of electrochemical cells with nanocrystalline Ag electrodes

The open circuit voltage of the electrochemical cell Ag (nano)|solid silver electrolyte|Ag (macro) is found to be inherently unstable. Even under conditions which support the morphological stability of the arrangement of nanocrystalline silver, the particles grow significantly as soon as they function as electrodes; i.e. when they are in contact with a silver electrolyte and connected electronically at the same time. The process is shown to be due to electrochemical Ostwald ripening with the interfacial transfer of Ag⁺ through the Ag/electrolyte interface being the rate limiting step. Its activation energy is 0.01 eV. The decay is in good agreement with modelling results.     

Threshold behavior of the formation of nanometer islands in a Ge/Si(100) system in the presence of Sb

Atomic-force microscopy is used to study the behavior of an array of Ge islands formed by molecular-beam epitaxy on an Si (100) surface in the presence of an antimony flux incident on the surface. It is shown that, as the Sb flux increases to a certain critical level, the surface density of the islands increases; however, if this critical level is exceeded, nucleation of the islands is suppressed and mesoscopic small-height clusters are observed on the surface. This effect is explained qualitatively in the context of a kinetic model of the islands’ formation in heteroepitaxial systems mismatched with respect to their lattice parameters.     

Single-laser approach for fluorescence guidance of excimer laser angioplasty at 308 nm: evaluation in vitro and during coronary angioplasty

BACKGROUND AND OBJECTIVE: Spectroscopic guidance of laser angioplasty has been attempted using a diagnostic He-Cd laser in addition to the therapeutic laser system. This study evaluated a single-laser approach for simultaneous ablation and fluorescence excitation. STUDY DESIGN/MATERIALS AND METHODS: A spectroscopy system was coupled to a clinical XeCl excimer laser. Ablation of 162 human aortic samples in saline and blood with 45 mJ/mm2 per pulse yielded 676 fluorescence spectra validated histologically. The same equipment was used in 16 patients for angioplasty of 18 coronary stenoses applying 500 to 1,725 pulses with 45 to 60 mJ/mm2 under saline flushing. A total of 783 spectra were recorded and validated by intracoronary ultrasound (categories: atheroma, fibrous plaque, calcified lesion). RESULTS: In vitro, 5 types of spectra could be differentiated: (1) atheroma, (2) fibrous plaque, (3) calcified lesion in saline, (4) media, and (5) calcified lesion in blood. Discriminant analysis prospectively classified 576 validation spectra with the following sensitivity and specificity for each type: (1) 83.5 and 97.1%, (2) 85.7 and 96.8% (3) 100 and 98.5%, (4) 98.1 and 99.3%, (5) 98.9 and 100%, respectively. In vivo type 1, 2, 3, and 5 spectra were also observed, but not the media spectrum. The predominant sonographic category also prevailed in spectroscopy. Calcified lesions yielded type 3 and 5 as well as mixed spectra. CONCLUSIONS: Using an excimer laser for angioplasty allows combining ablation and fluorescence excitation without a diagnostic laser. Principal types of atherosclerotic lesions and the media can be differentiated spectroscopically with this approach.     

The impact of relative radiometric calibration on the accuracy of kNN-predictions of forest attributes

The k-nearest-neighbour (kNN) algorithm is widely applied for the estimation of forest attributes using remote sensing data. It requires a large amount of reference data to achieve satisfactory results. Usually, the number of available reference plots for the kNN-prediction is limited by the size of the area covered by a terrestrial reference inventory and remotely sensed imagery collected from one overflight. The applicability of kNN could be enhanced if adjacent images of different acquisition dates could be used in the same estimation procedure. Relative radiometric calibration is a prerequisite for this. This study focuses on two empirical calibration methods. They are tested on adjacent LANDSAT TM scenes in Austria. The first, quite conventional one is based on radiometric control points in the overlap area of two images and on the determination of transformation parameters by linear regression. The other, recently developed method exploits the kNN-cross-validation procedure. Performance and applicability of both methods as well as the impact of phenology are discussed.     

Brief Overview of Recent Developments on Negative Phase–Velocity Mediums (alias Left–Handed Materials)

This brief overview covers a rapidly occurring development in the area of microwave composite materials: isotropic dielectric–magnetic mediums wherein the phase velocity vector and the time–averaged Poynting vector are oppositely directed. Such materials have also been inappropriately designated as left–handed materials. Ramifications for aberration–free lenses, homogenization approaches, and complex mediums are also presented.     

Histochemical detection of lymphatic drainage pathways in the middle nasal meatus

AIM: Assessment of the antihypertensive effect of doxazosin, alpha-1 blocker, as well as its action on lipid and carbohydrate metabolism, microcirculation and platelet function in patients with non-insulin-dependent diabetes mellitus (NIDDM). MATERIALS AND METHODS: Doxazosin (tonocardin) treatment was given for 11 weeks to 33 NIDDM patients with concomitant hypertension. The clinical examination comprised evaluation of central hemodynamics, vessels of the fundus of eye, lipid and carbohydrate metabolism, renal function, platelet aggregation. RESULTS: Tonocardin produced a fall in the systolic blood pressure (BP) by 14%, in the diastolic BP--by 17%. The 24-h profile of BP, lipid and purine metabolism, microcirculation of the vessels of the fundus of eye also improved. Total peripheral vascular resistance, left ventricular myocardial mass and platelet aggregation. Carbohydrate metabolism remained unchanged. CONCLUSION: Monotherapy with tonocardin (2-8 mg/day) is effective and safe in the treatment of arterial hypertension in NIDDM patients.