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Temperature-dependent photoluminescence measurements and deep level transient spectroscopy have been made to identify defects and deep level traps in InGaAsN alloys lattice-matched to GaAs. The epitaxial layers were grown by molecular beam epitaxy at different substrate temperatures. Defect levels responsible for the quenching of luminescence with increase of temperature have been identified. Several electron trap levels have been identified and characterized in the alloys. The concentrations of all of these increase with N content in the alloy. A dominant center, with an activation energy of ET=0.44eV, is present in all the samples and its concentration is inversely proportional to photoluminescence intensity. H2O and O present in the source nitrogen are believed to be responsible for the presence of this trap, which also has characteristics similar to the E3 and E4 levels in molecular beam epitaxial GaAs.

The characterization of a block copolymer consisting of blocks of tetrahydrofuran, THF, and methyl methacrylate, MMA, was attempted with the aid of liquid chromatography, LC, at the critical adsorption point, CAP. The conditions applying to the CAP at 30°C for the homopolymers are: PTHF: eluent composition: THF:acetonitrile = 50:50, w/w; column: Nucleosil C18. PMMA: eluent composition: THF:n-hexane = 81.8:18.2, w/w; column: bare silica gel. The presence of homo PTHF and of homo PMMA in the crude block copolymer was evidenced. Moreover, chromatography at the CAP for PMMA showed that the block copolymer contains multiblock (triblock) fractions. The formation of triblock copolymer is expected when the polymerization of MMA is terminated (partially) by combination. In conclusion, LC at the CAP is a powerful tool to characterize block copolymers regarding the presence of homopolymer and multiblock (triblock) fractions.

A new size exclusion chromatographic procedure for determination of complexation of macromolecules with low molar mass substances (such as preferential solvation or drug-protein-binding) was proposed. The method is based on the assessment of system peaks formed as result of differences between eluent composition and bulk solvent composition due to the complexation within the initial sample solution. The composition of the eluent, which contains the same components as the sample solvent, is adjusted in such a way that the system peak disappears. Under these circumstances the bulk solvent composition equals to the eluent composition and the former can be easily calculated. This procedure was tested by measuring the preferential solvation in a model system polystyrene plus toluene plus methanol and by comparing the result with the data obtained with two other chromatographic methods.

The ion layer gas reaction (ILGAR) is a novel deposition technique for chalcogenide compounds. This sequential and cyclic method, which involves a solid-gas reaction, is used to deposit sulfidic buffer layers on Cu(InGa)(S,Se)/sub 2/ (CIGSSe) absorbers. Chemical pretreatments of the absorber in several metal salt baths are investigated, which improve the device performance of the solar cell significantly. In the case of a Zn-bath a temperature above 100/spl deg/C forces the modification of the absorber surface resulting in a drastic increase of the open circuit voltage with increasing bath temperature. As a first result the combination of Cd-pretreatment and ILGAR-CdS buffer in a solar cell (0.5 cm/sup 2/) yields an efficiency of 14.2 % (total area) comparable with the quality of the corresponding standard device (CBD-CdS buffer, /spl eta/=14.1%); the Cd-free combination of Zn-pretreatment and ILGAR-ZnS buffer also results in a device with an efficiency of 14.2 % (total area).

To evaluate the different methods for grading mitral regurgitation (MR) by transesophageal echocardiography (TEE) in patients with clinical suspicion of mitral prosthesis dysfunction.Cardiac catheterization (Cath) was performed in 15 patients for grading the severity of prosthetic MR, divided in two groups based on the presence or absence of severe MR. Prosthetic MR was quantified by TEE using methods commonly used for MR of native valves: subjective assessment by color Doppler, objective assessment based on absolute jet area and on its relative area (jet area/left atrial area) and assessment based on the presence of systolic flow reversal in pulmonary vein.Prosthetic MR was mostly transprosthetic (14 patients) and eccentric (11 patients). There was significant correlation (p0.05) between Cath and TEE for identification of severe MR based on subjective assessment and on the presence of systolic flow reversal in pulmonary vein. Identification based on absolute (jet area7 cm2) and relative (jet area35% of left atrial area) jet areas did not reveal significant correlation with the angiographic grade and showed clear underestimation by TEE when the last method was used. However, there was good correlation (p0.05) if relative jet areas30% were considered as cut point.TEE correctly identified angiographic severe mitral prosthesis regurgitation, mainly by the presence of systolic flow reversal in pulmonary vein and subjective assessment. The estimation of severity of the prosthetic MR by absolute or relative jet area seems to be limited and should be used with caution due to eccentricity of the regurgitant jet, frequently seen in mitral prosthesis dysfunction.

Wahrend die Allgemeinmedizin Europas uber die niederlandischen Faktoreien schon im 18. Jahrhundert Japan beeinfluste, blieb die Zahnheilkunde davon unberuhrt. Um 1870 kam es zu ersten Kontakten mit der — damals fuhrenden — amerikanischen Zahnheilkunde. Es waren Zahnarzte, die in Japan eine Praxis grundeten und Japanern, die um Belehrung baten, Unterricht erteilten. In der Folgezeit wurden nach amerikanischem Muster Colleges gegrundet, die Zahnheilkunde entwickelte sich zum selbstandigen Hochschulfach. Zu Beginn des 20. Jahrhunderts gingen Japaner zur Weiterbildung sowohl nach Deutschland wie in die USA. Als Beispiel mag Prof. Toru Shimamine (geboren 1879) gelten, der von 1907–1914 an den Universitaten Berlin und Breslau tatig war, neben kleineren Arbeiten zwei bemerkenswerte Forschungsergebnisse veroffentlichte und 1913 und 1914 an internationalen Kongressen teilnahm (Abb. 1). In Breslau arbeitete Shimamine zuerst bei Geheimrat Partsch, dann bei Prof. Euler, in Berlin bei Prof. Dieck. Ich hatte das Gluck, ihn als junger Privatdozent bei Prof. Euler bei einem seiner spateren Besuche in Breslau zu erleben. Von der Universitat Breslau erhielt er die Ehrendoktorwurde.

Infrared light emission is demonstrated from In0.4Ga0.6As self-organised quantum dots in a quantum cascade structure incorporating a GaAs/GaAsN chirped superlattice. A TE polarised emission peak is observed at 22 µm, corresponding to the calculated first-excited to ground-state transition. Other emission peaks also correspond to predicted values.

(1933). Questions, Discussions, and Notes. The American Mathematical Monthly: Vol. 40, No. 5, pp. 282-287.

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Following the report given at the FDI congress in Chicago in 1975, the question is raised about the present state of acrylic filling materials, i.e. whether further developments are necessary or even possible. The importance of clinical testing is emphasized and the problems involved in chemical binding to the dental hard substances discussed. The influence of the thermal coefficient of expansion on the marginal seal is discussed in connection with marginal discoloration, and acid cauterization as well as remineralization are critically evaluated. The significance of wear and tear for maintaining the contours is emphasized, especially in connection with occlusal fillings of lateral teeth, as well as the problem of shaping a contact point and tensile strength after repair of an old filling. Improvements in UV light polymerisation are described. The different opinions on the importance of histological findings regarding pulp tolerance are critically discussed and finally the significance of water uptake and radiological opacity is delt with. In conclusion, the indication for acrylic filling materials at the present time is defined.

Following the 1975 report in Chicago, an attempt is made to discover the present position with regard to the development of composite filling materials, and to determine whether further development is necessary or even possible. The reasons for considering clinical trials important are given, and the problem of the chemical bond to hard dental tissues is discussed. The influence of the thermal coefficient of expansion on the marginal seal is discussed in relation to border discolouration, and a critical assessment given of acid etching and remineralization. The significance of wear for the maintenance of contours is pointed out, in particular in connection with occlusal surface fillings in the cheek teeth, as well as the problem of contact-point characterization and fracture strength after repair of an old filling. Improvements in UV light polymerization are described. A critical discussion of the different opinions on the significance of histological findings in relation to pulp tolerance is presented, and finally the significance of water uptake and radiological opacity is discussed. In conclusion indications in relation to the present state of development are listed.