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Zusammenfassung: Durch Ultraschallexposition von 33 Dermatophytenstammen diverser Spezies gewonnenes Pilzplasma wurde mittels des Zweistrahl-UV-Spektrometers Cary 14 (Fa. Varian) und des Fluoreszenzspektrophotometers (Perkin-Elmer MDF-3 L) auf lichtabsorbierende und fluoreszierende Substanzen untersucht. Dabei zeigten sich selbst bei artgleichen Pilzstammen weitgehend individuelle Fluoreszenzprofile. Im einzelnen waren in den Pilzplasmen sowohl graduell veranderte Fluoreszenzbanden des verwandten Sabouraud-Agars, als auch weitere, im Nahrmedium nicht nachzuweisende Fluoreszenzqualitaten, anzutreffen. Insgesamt neigen kaum pigmentierende weis-grun-gelbliche Pilzspezies mehr zu kurzwelligerer, hingegen rotlich oder braunlich pigmentierende Arten mehr zu langwelligerer Fluoreszenz. Zur Begrundung oder zur Korrektur der konventionellen Klassifizierung der Fungi tragen obige Fluoreszenzstigmata kaum etwas bei. Als kompliziert erwies sich auch die chemische Bestimmung der fluoreszierenden Pilzsubstanzen, zumal der blose Vergleich der Fluoreszenzprofile definierter und unbekannter Stoffe nicht zu deren Identifizierung ausreicht. Die Varianz des Fluoreszenzverhaltens unter den einzelnen Stammen einer Spezies weist auf eine uberraschend grose Anzahl von Allelen fur den betreffenden Gen-Locus hin. Eine die Adaptation der Spezies an veranderte Umweltbedingungen erhohende Vielfalt multipler Allele auch anderer Gen-Loci ist zu vermuten. Summary: Ultraviolet absorption and fluorescence emission of plasm from several species of the genera Microsporum, Trichophyton and Epidermophyton were examined in vitro. The plasmatic material was prepared by exposure of 33 different strains to ultra-sound. We found that the intensity and the quality of fluorescence differed to a certain extent among individual strains of the mycetes. Only minimal correlation in fluorescence spectra was detected between strains of the same species. Generally, uncoloured species seem to have fluorescence bands in the region of shorter wave-lengths while species with red or brown pigment formation tend to a fluorescence in the region of longer wave-lengths. Measurement of UV-absorption and fluorescence provide no criteria for the identification or conventional classification of the dermatophytes. It is impossible to identify the chemical nature of the fluorescent substances exclusively by spectrum-analysis.

SIGNIFICANCE\ud \ud Enhanced levels of reactive oxygen species (ROS) have been associated with different disease states. Most attempts to validate and exploit these associations by chronic antioxidant therapies have provided disappointing results. Hence, the clinical relevance of ROS is still largely unclear.\ud \ud RECENT ADVANCES\ud \ud We are now beginning to understand the reasons for these failures, which reside in the many important physiological roles of ROS in cell signaling. To exploit ROS therapeutically, it would be essential to define and treat the disease-relevant ROS at the right moment and leave physiological ROS formation intact. This breakthrough seems now within reach.\ud \ud CRITICAL ISSUES\ud \ud Rather than antioxidants, a new generation of protein targets for classical pharmacological agents includes ROS-forming or toxifying enzymes or proteins that are oxidatively damaged and can be functionally repaired.\ud \ud FUTURE DIRECTIONS\ud \ud Linking these target proteins in future to specific disease states and providing in each case proof of principle will be essential for translating the oxidative stress concept into the clinic. Antioxid. Redox Signal. 23, 1171-1185.

Fragestellung Untersuchung der anteiligen Bedeutungen von Sport und Reduktionsdiat auf den Ernahrungszustand, die gesundheitlichen Risikofaktoren und die aerobe Fitness bei adiposen, pramenopausalen Frauen. Material und Methodik Gruppe I (n = 12; BMI: 37,7 ± 4,4 kg/m2): vier Wochen Sport, gefolgt von vier Wochen Sport (Nordic Walking, dreimal/Woche je 60 min) und Diat (BCM®-Diat, ca. 1200 kcal/Tag); Gruppe II (n = 8; 38,0 ± 4,9 kg/m2): vier Wochen Diat, gefolgt von vier Wochen Diat und Sport. Vor Intervention (T0), nach vier Wochen Sport oder Diat (T1) und am Ende der achtwochigen Intervention (T2) wurden der Ernahrungszustand (Taillenumfang, Fettmasse), kardiovaskulare Risikofaktoren (Triglyzeride, Gesamt-, LDL- und HDL-Cholesterin, Glukose) und aerobe Fitness (submaximale O2-Aufnahme) gemessen. Der Energieverbrauch wahrend des Sportprogramms wurde mittels HF-Monitoring erfasst. Ergebnisse Sport steigerte die aerobe Fitness, hatte aber keinen Einfluss auf den Ernahrungszustand und das Risiko. Diat verbesserte den Ernahrungszustand, hatte aber keinen Effekt auf Risikofaktoren und Fitness. Sport und Diat im Anschluss an Sport verbesserte den Ernahrungszustand und das Risikoprofil, zeigte aber keinen weiteren Effekt auf die Fitness. Diat und Sport direkt nach Diat verbesserte weiter den Ernahrungszustand, hatte aber keinen weiteren Einfluss auf das Risikoprofil und die Fitness. Der Energieverbrauch beim Sport war in Gruppe I hoher im Vergleich zu Gruppe II. Schlussfolgerung Die beiden Interventionsprogramme zeigen ahnliche Effekte auf den Ernahrungszustand. In der Gruppe I waren zusatzlich Verbesserungen der gesundheitlichen Risikofaktoren und aeroben Ausdauer zu beobachten, nicht jedoch in der Gruppe II. Diese Daten sprechen dafur, Therapieprogramme mit einer Steigerung der korperlichen Aktivitat zu beginnen und die Diat erst in der zweiten Phase einzufuhren. Background To investigate the effect of exercise (e. g. Nordic Walking, one hour training session for three times a week) and caloric restriction (BCM-diet®, 1200 kcal/d) on body composition, health risk factors and aerobic capacity in obese premenopausal women. Material and methods 20 Obese women were assigned to one of two groups. Group I (n = 12; BMI: 37.7 ± 4.4 kg/m2): exercise for four weeks, followed by exercise and caloric restriction for four weeks. Group II (n = 8; BMI = 38.0 ± 4.9 kg/m2): caloric restriction for four weeks, followed by caloric restriction and exercise for four weeks. Body composition (waist circumference, fat mass), health risk factors (plasma lipids, blood pressure) and aerobic capacity (oxygen uptake) were measured before intervention (T0), after four weeks exercise or caloric restriction (T1) and after four weeks of caloric restriction and exercise (T2). Energy expenditure during exercise was measured by heart-rate monitoring. Results Exercise increased aerobic capacity. By contrast, body composition and cardiovascular risk factors were unchanged. Caloric restriction decreased waist circumference and fat mass but did not improve health risks and aerobic capacity. Exercise and caloric restriction after exercise decreased waist circumference, fat mass and cardiovascular risk factors, but there was no effect on aerobic capacity. Caloric restriction and exercise after caloric restriction improves body composition but there was no change in risk factors and aerobic capacity. Energy expenditure during exercise was higher in Group I compared to Group II. Conclusions Both intervention trials showed similar effects on body composition. There was an additive effect of a longer exercise intervention (Group I) on risk factors and aerobic capacity. After 8 weeks of caloric restriction (Group II) no additional effect on the investigated parameters was seen. These data suggest that further interventions ought to start with exercise before introducing caloric restriction in the 2nd part.

Studies with seedlings of tropical rainforest trees ( Calophyllum longifolium Willd.; Tectona grandis L. f.) were designed to test whether high-light stress affects photosynthetic performance and growth. Seedlings were cultivated in pots at a field site in Central Panama (9 degrees N) and separated into two groups: (1) plants exposed to full solar radiation; (2) plants subjected to automatic neutral shading (48 %) whenever visible irradiance surpassed 1000, 1200, or 1600 micromol photons m-2 s-1. After 2-4 months, chlorophyll fluorescence (Fv/Fm ratio), photosynthetic net CO2 uptake, pigment composition, alpha-tocopherol content of leaves, and plant biomass accumulation were measured. Fully sun-exposed, compared to periodically shaded plants, experienced substantial high-light stress around midday, indicated by photoinhibition of photosystem II and depressed net CO2 uptake. Higher contents of xanthophyll cycle pigments, lutein, and alpha-tocopherol showed an enhancement of photoprotection in fully sun-exposed plants. However, in all experiments, the maximum capacity of net CO2 uptake and plant dry mass did not differ significantly between the two treatments. Thus, in these experiments, high-light stress did not impair productivity of the seedlings studied. Obviously, the continuously sun-exposed plants were capable of fully compensating for any potential costs associated with photoinhibition and repair of photosystem II, reduced CO2 assimilation, and processes of high-light acclimation.

Although noise thermometry is an established technique for absolute temperature measurement, several aspects needed to be clarified before this method can be employed for temperature measurement in a space furnace at 1800°C. First, the electrical insulation resistance for sheathed sensors with different insulation materials were measured. Five test sensors with outer diameters of 3.2 mm or less were fabricated and tested. The measurements clearly show a significant advantage for the pyrolytic boron nitride (pBN) insulation compared to Hafnium oxide. The electrical insulation resistance values at 1800°C for the sensors with HfO 2 were below 10 Ω, whereas pBN-insulated test sensors exhibited values of more than 600 Ω for the same diameter. Furthermore, no difference has been found between the resistance of bent and straight sensors. Based on these results a miniaturised and bent noise thermometer with a diameter of 3.2 mm having a pBN insulation was fabricated. This sensor and additional control thermocouples were subjected to performance tests up to 1800°C in a space-compatible furnace. All sensor readings exhibited a consistent figure during the tests. The noise thermometer, however, showed always the highest reading indicating that noise thermometry is an appropriate method for accurate measurements of absolute temperatures, even in the harsh environment of a compact multi-zone space furnace.

The aim of the present study was to compare variables of metabolism, physical activity and fitness to body composition in normal and overweight children in a cross-sectional study design. Body composition was assessed by anthropometric measurements and bioelectrical impedance analysis in forty-eight prepubertal children (age 5–11 years, thirteen normal-weight, thirty-five overweight). Total energy expenditure (EE) was measured by combination of indirect calorimetry (for measurement of resting EE) and individually calibrated 24 h heart-rate (HR) monitoring. Activity-related EE and physical activity level (PAL) were calculated. Time spent with min-by-min HR>FLEX HR was also used as a marker of moderate habitual and vigorous activities. Aerobic fitness (O2 pulse (O2 consumption:HR at submaximal steady-state heart rate), submaximal O2 consumption (VO2submaximal), RER at a HR of 170 beats per min) was determined by bicycle ergometry. Muscle strength of the legs (maximal isometric strength of musculus quadriceps and of musculus ischiocruralis (Fa max and Fb max respectively)) was measured by computer tensiometry. When compared with normal children, overweight children had higher skinfold thicknesses (sum of skinfold thicknesses at four sites +160%), fat mass (+142%), waist (+24%) and hip circumferences (+14%), resting EE (+13%) and RER (+5%). No significant group differences were found for fat-free mass, muscle mass, total EE, activity-related EE, PAL, HR>FLEX HR, VO2submaximal, O2 pulse, Fa max and Fb max as well as the fat-free mass- or muscle mass-adjusted values for resting EE, aerobic fitness and muscle strength. When compared with normal children, overweight children had a lower measured v. estimated resting EE (Δ resting EE) and spent more time watching television. There were positive relationships between fat-free mass(x) and resting EE(x), total EE(y), aerobic fitness(y) and muscle strength(y), but only Δ resting EE(x) and HR>FLEX HR(x) correlated with fat mass(y). In a stepwise multivariate regression analysis resting EE adjusted for fat-free mass and Δ resting EE were significant determinants of % fat mass and explained 29·7% of its variance. Thus, in the present cross-sectional study, resting EE was the most important determinant of fat mass.

Acclimation to periodic high-light stress was studied in tree seedlings from a neotropical forest. Seedlings of several pioneer and late-succession species were cultivated under simulated tree-fall gap conditions; they were placed under frames covered with shade cloth with apertures of different widths that permitted defined periods of daily leaf exposure to direct sunlight. During direct sun exposure, all plants exhibited a marked reversible decline in potential photosystem II (PSII) efficiency, determined by means of the ratio of variable to maximum Chl a fluorescence (F(v)/F(m)). The decline in F(v)/F(m) under full sunlight was much stronger in late-succession than in pioneer species. For each gap size, all species exhibited a similar degree of de-epoxidation of violaxanthin in direct sunlight and similar pool sizes of xanthophyll cycle pigments. Pool sizes increased with increasing gap size. Pioneer plants possessed high levels of beta-carotene that also increased with gap size, whereas alpha-carotene decreased. In contrast to late-succession plants, pioneer plants were capable of adjusting their Chl a/b ratio to a high value in wide gaps. The content of extractable UV-B-absorbing compounds was highest in the plants acclimated to large gaps and did not depend on the successional status of the plants. The results demonstrate a better performance of pioneer species under high-light conditions as compared with late-succession plants, manifested by reduced photoinhibition of PSII in pioneer species. This was not related to increased pool size and turnover of xanthophyll cycle pigments, nor to higher contents of UV-B-absorbing substances. High beta-carotene levels and increased Chl a/b ratios, i.e. reduced size of the Chl a and b binding antennae, may contribute to photoprotection in pioneer species.

Polymerization and chemical reactions taking place in supercritical fluids (SCFs) are often combined with the formation and precipitation of insoluble products. The properties and quality of a formed product are significantly influenced by its particle size. To control and regulate the product precipitation during an SCF process measurement, techniques are required to monitor online particle sizes and particle growth. This paper presents the adaptation of the so-called three-wavelength-extinction technique to a dynamic sc-CO 2 process containing fine solid particles or droplets of immiscible liquids. This technique allows the simultaneous determination of mean particle sizes and particle concentrations in dispersed systems. The measuring principle is based on the extinction of monochromatic light at three different wavelengths due to absorption and dispersion, as described by the MIE theory. However, for the application of the three-wavelength-extinction technique to a SCF process, the strong influence of pressure and temperature on the optical properties of supercritical fluids must, in particular, be considered. Systematic studies investigating TiO 2 particles suspended in sc-CO 2 have shown that reliable particle size measurements can be achieved whenever the specific refractive index of sc-CO 2 is taken into account. Particle sizes determined by the three-wavelength-extinction technique under sub- and supercritical conditions were in excellent accordance with particle sizes obtained by conventional offline measurement techniques. In addition to the characterization of fine particles, the three-wavelength-extinction technique is also suitable for size measurements of droplets in sc-CO 2 . For example, droplets being formed during the mixing of dimethylformamide (DMF) and sc-CO 2 and dimethyl sulfoxide (DMSO) could be observed and analyzed in real time. In general, one can conclude that the three-wavelength-extinction technique is a suitable tool for monitoring and analyzing the formation of particles and droplets during a supercritical fluid process.

The purpose of this study was to determine whether change of forest cover had an effect on the development of the organic surface horizons, particularly on those variables that influence nutrient cycling and forest productivity. Jack pine (Pinus banksiana Lamb.) and black spruce (Picea mariana [Mill.] B.S.P.) plantations were selected from among the youngest to oldest (2–16 yr) within a 100 km2 area in southeastern New Brunswick. Natural forests were also included as benchmark sites. The forest floor and tree foliage was sampled and trees measured on 0.05-ha plots. The forest floor samples were used to determine organic mass, nutrient contents and pH. In pine plantations, organic matter accumulated rapidly during the period of exponential tree growth, but leveled off at about 45 Mg ha–1. This was within the range of benchmark sites with mixed conifer-hardwood cover. In spruce plantations, the forest floor mass ranged upward to 77 Mg ha–1. Development was strongly influenced by the nature of the previous forest. Spruce forest floors were on average more acid and had lower nutrient concentrations, particularly N and Ca. The observed differences suggest that nutrients are recycled more rapidly in the pine plantations, partly explaining the superior growth of the latter. Key words: Forest floor, Kalmia angustifolia L., Picea mariana (Mill.) B.S.P., Pinus banksiana Lamb., nutrient cycling, plantation forest

The new energetic material ammonium dinitramide (ADN), NH 4 N(NO 2 ) 2 , has been investigated with regard to its thermal properties and decomposition behaviour. Thermal decomposition of ADN is observed after complete melting at 91.5 °C. The main decomposition pathway is based on the formation of NH 4 NO 3 and N 2 O followed by the thermal decomposition of NH 4 NO 3 to N 2 O and H 2 O at higher temperatures. Side reactions forming NO 2 , NO, NH 3 , N 2 and O 2 are described and a mechanism for the acid-catalyzed decomposition of hydrogen dinitramide, dissociation product of ADN, is proposed.

Raman spectroscopy increasingly becomes a valuable analytical tool in biomedicine. A novel Raman microscope designed for biomedical applications was used to discriminate viability states and cell types of Hodgkin’s disease as well as different neural and invading glioblastoma cells within a human engineered neural tissue (ENT).

Photoinhibition of photosynthesis was monitored by means of chlorophyll a fluorescence in leaves of plants growing in 60–80 m2 light gaps in a moist tropical lowland forest located on Barro Colorado Island in central Panama. In these forest gaps, photon flux density was low (less than 100 μmol photons m−2 s−1) during most of the day, but increased on clear days to 1.7-1.8 mmol photons m−2 s−1 for 1–2 h during midday. Nine species representing different taxa and life-forms were examined. Leaves of all species exhibited substantial photoinhibition in situ during high light exposure, as manifested by a decrease in the ratio of variable to maximum fluorescence emission, FV/FM. Recovery (reversion of fluorescence quenching) took place in the shade following high light exposure. The major part of recovery occurred in a fast phase within about 1 h after the high light period. A slow phase of recovery proceeded for another 4–5 h until sunset. After 30–60 min of recovery in the shade, calculated rates of PSII electron transport remained significantly (5–15%) reduced in comparison to rates obtained prior to high light exposure; after about 2 h of recovery, inhibition was negligible. All species responded to the high light periods and following shade periods in a very similar manner. It is concluded that photoinhibition and recovery exhibited by these gap leaves reflect a dynamic regulatory mechanism of thermal energy dissipation that allows plants of different life-forms to cope with periods of high light in tropical forest gaps.

Elemental concentrations (H, Ca, Mg, K, Na, NH4-N, NO3-N, P) and water flux data for precipitation and stream discharge as well as ion concentration data for soil solutions were collected and summarized for the Hayden Brook (HB) and Narrows Mountain Brook (NMB) watersheds of the Nashwaak Experimental Watershed Project (NEWP) in Central New Brunswick. Elemental concentrations, fluxes and stream discharge from both watersheds were compared for pre- and post-harvest periods (1972–1978 and 1978–1984, respectively). For soil and streamwater solutions, elemental concentrations were typically highest in late summer to fall, and continued to be high throughout the dormant season. For the soil solution, concentrations of NO3-N, NH4-N, Ca and K peaked in midsummer. Highest NO3-N concentrations were found in post-harvest soil solutions taken from hardwood sites. Nitrate levels were low in soil solutions taken from conifer sites, with post-harvest levels slightly higher than pre-harvest levels. Soil solution concentrations were found to vary with soil depth: pH values were lowest at the surface, and increased uniformly with depth; bases (Ca, Mg, K, Na) and NO3-N tended to be lowest at intermediate soil depth. Seasonally divergent trends were observed for post-harvest NO3-N in soil solutions and in streamwater: midsummer levels were high in the former, but low for the latter. Several aspects likely contributed to this divergence: (1) enhanced rates of N mineralization and nitrification in upland soils during post-harvest midsummers, (2) reduced post-harvest vegetational N uptake, (3) possibly accelerated N absorption by microbes and vegetation in the wet areas of the cut watershed. Altogether, post-harvest effects on stream discharge and streamwater chemistry were short-term: differences for elemental concentrations and stream discharge became insignificant after about 5 and 10–12 yr, respectively. Vegetation, especially tolerant hardwoods, recovered rapidly from stump and root sprouts. Key words: Clearcutting, stream discharge, soil solution, pH, Ca, Mg, K, Na, P, NO3-N, NH4-N, seasonal trends

The high-energy Zn+ ion implantation of InP is a promising method for the formation of buried p-type conducting layers. Defect properties and inclusion mechanism of zinc implanted samples with energies of 1.2 and 2.5 MeV to doses of 5 × 1014−5 × 1015 cm−2 at a temperature of 200°C were investigated with ion beam methods, XTEM and SNMS to some extent. Also the influence of rapid thermal annealing on the structural properties was studied. After implantation we found no evidence for amorphization or extended defects but point-like defects. During annealing the surface region recovered nearly completely while in depth the point-like defects agglomerated in dislocation loops. Further we observed a remarkable redistribution of the Zn atoms due to annealing.

Delayed pulsed-field ionization of long-lived high Rydberg states yields vibrationally and partly rotationally resolved spectra of polyatomic molecular ions and of cluster ions when the resulting threshold ions are measured as a function of the excitation energy. The field ionized threshold ions are monitored and separated from the non-energy-selected ions in a reflecting field mass spectrometer with high mass resolution. The decay of the molecular or cluster ion core is monitored by the appearance of threshold ions at the daughter ion mass as a function of the selectively excited vibrational state. In this way, upper limits for dissociation thresholds of neutral and ionized dimers are obtained which are smaller than recent theoretical values from the literature. The appearance of daughter fragment ions after delayed pulsed-field ionization indicates that high Rydberg orbits are not destroyed by the dissociation of the core. Possible applications of our technique for the production of state-selected ions are discussed.

InP is a promising material for use in optoelectronic and microwave devices. Doping of InP with foreign atoms is applied for obtaining p-type conductivity, one dopant of interest being zinc. We investigated InP doped with zinc by diffusion in a semiclosed system as well as by implantation using various implantation conditions trying to find the position of the zinc atoms in the host lattice. For that we used the ion channeling effect in conjunction with proton induced X-ray emission and Rutherford backscattering spectrometry along some axial and planar directions of the InP crystal. The ratio of interstitial to substitutional zinc atoms was investigated for both the as-doped and the annealed state. The results of the ion beam experiments were compared with those of Hall effect and SIMS measurements.

Positron lifetime τ measurements are performed to study defect annealing and decomposition in Al–(0.003 to 0.36 at%) Sc alloys during isochronal and isothermal heat treatment of water-quenched samples. A two-stage behaviour of the positron lifetime observed below 200°C is explained as migration and clustering of quenched-in vacancy-Sc atom complexes followed by the annealing of vacancy clusters. In alloys containing 0.18 and 0.36 at% Sc an extra peak appears in the average positron lifetime around 300°C which is attributed to the precipitation of coherent Al3Sc particles. Although the volume fraction of Al3Sc is very small, f ≈ 0.5%, the precipitates are detected by positrons due to their fine-disperse distribution (diameter ≈ 10 nm). A vacancy-type lifetime component which appears simultaneously with the precipitate formation is attributed to structural vacancies of the Al3Sc phase or to vacancies associated with the Al3Sc particle-matrix interface. Positronlebensdauer(τ)-Messungen werden durchgefuhrt, um die Defektausheilung und Entmischung in Al–(0,003 bis 0,36 At%) Sc-Legierungen wahrend isochroner und isothermer Warmebehandlung von in Wasser abgeschreckten Proben zu untersuchen. Ein zweistufiges Verhalten der Positronenlebens-dauer unterhalb von 200°C wird mit der Wanderung und Agglomeration von eingeschreckten Leerstellen-Sc-Atom-Komplexen und der nachfolgenden Ausheilung der Leerstellenagglomerate erklart. In Legierungen mit 0,18 und 0,36 At.% Sc wird ein zusatzlicher Peak in der mittleren Positronenlebensdauer bei 300°C beobachtet, welcher auf die Ausscheidung von koharenten Al3Sc-Teilchen zuruckgefuhrt wird. Obwohl der Volumenanteil von Al3Sc mit f ≈ 0,5% sehr gering ist, werden die Ausscheidungen aufgrund ihrer feindispersen Verteilung (Durchmesser ≈ 10 nm) durch Positronen nachgewiesen. Eine leerstellenartige Positronenlebensdauerkomponente, welche simultan mit der Ausscheidungsbildung erscheint, wird auf strukturelle Leerstellen der Al3Sc-Phase oder auf Leerstellen, welche mit der Al3Sc-Teilchen-Matrix-Grenzflache verbunden sind, zuruckgefuhrt.

New developments in time-of-flight mass spectrometry combined with multi-photon ionization provide hitherto unachievable information on the decay of weakly bound cluster ions. Dissociation thresholds of cluster ions are important for the understanding of their binding and structure. We present two experimental methods that allow the determination of dissociation energies of weakly bound ionic and neutral clusters. Besides the breakdown technique observing the metastable ion efficiency curves, a novel method is presented and described which is based on delayed pulsed field ionization of long-lived Rydberg states close to the ionization energy. In this way state-selected benzene—noble gas ions are produced and their decay is observed in a reflectron mass spectrometer. Results for dissociation thresholds of various molecular dimers and larger complexes of aromatic molecules are presented. The pronounced differences in dissociation energy between the neutrals and the ions are interpreted in terms of charge-transfer resonance interaction in the ionic complex leading to structural changes after the ionization process.

In the epidermal layers of rye primary leaves two flavone glycosides and several hydroxycinnamoyl esters are localized, whereas the mesophyll contains two flavone glucuronides and two anthocyanins. The concentrations of all these potential UV-B protective phenylpropanoid compounds could be reduced by application of 2-aminoindan-2-phosphonic acid (AIP), an efficient inhibitor of phenylalanine ammonia-lyase (EC 4.1.3.5). Photosystem II in the primary leaves of seven-days-old plants, grown in the presence of 20 μm AIP up to an age of 80 h, was more severely affected by UV-B than in control plants with the normal concentration of phenylpropanoid compounds. Damage of photosystem II in vivo was estimated by measuring the chlorophyll a fluorescence (parameter FJFm) of PS II. The results indicate an essential role of phenylpropanoid com pounds as UV-B protectants in rye primary leaves

Four van der Waals vibrational states of the (benzene-Ar) + cation are selectively excited by resonance-enhanced two-photon ionization and detected with the delayed pulsed field threshold ionization technique. Selection of different intermediate van der Waals states in the 6 1 (S 1 ) state of the neutral benzene—Ar dimer leads basically to excitation of the same vibrational species in the ion. This propensity rule and other arguments are used to assign the van der Waals states in the neutral and the ionic dimer. As a result a strong anharmonicity in the stretching and the bending coordinate is found.

In this work the unimolecular decay of cluster ions is investigated in order to deduce energetic and structural information on clusters as a function of size. The dissociation behavior of benzene cluster ions (C6H6)+n with n = 4 to n = 200 is observed after multiphoton ionization of a neutral benzene cluster beam within a reflectron mass spectrometer. With a pulsed deflection technique of undesired ions the metastable decay of mass-selected cluster sizes within the drift region was observed. The metastable decay efficiency is monotonically increasing in this mass range but pronounced anomalies are found at n = 14, 20, 24, and 27. Using an evaporative ensemble ansatz and an RRKM model with a phase space restricted to the intermolecular cluster modes we were able to determine the dissociation energies for clusters up to n = 23 from a fit of the calculated metastable decay ratios to the measured ones. For this fit the size dependent sequential evaporation of two benzene molecules is important. The dissociation energy is largest for the dimer cation and found to decrease for clusters up to n = 5. For larger clusters it begins to increase with a step-like behavior after n = 14 and n = 20. This is interpreted in terms of shell filling achieved for icosahedral structures about a center dimer cation.

We present results of the determination of Cd- and Zn-dopants in InP single crystals using the PIXE and RBS spectrometry at our 2 MeV Van de Graaff accelerator. The (100) oriented crystals were doped by thermodiffusion of Cd and Zn atoms. For concentration and localization measurements we used the ion-channeling technique and energy dispersive spectrometry of proton induced X-ray emission (PIXE). Angular scans of the K-lines of In, Cd and Zn were obtained. The strong In X-rays were attenuated by a rhodium foil in front of the low energy Ge detector. The PIXE-channeling results were compared with SIMS and Hall-effect measurements.

Pulsed field threshold ionization leads to a vibrationally resolved spectrum of the X 2E1g state of the benzene cation. It is further used to investigate the state‐selective dissociation of the benzene–Ar+ complex. Exclusive detection of threshold ions with a resolution of

The lattice position of Zn in InP is investigated using PIXE (proton-induced X-ray emission) combined with the channeling technique. The total Zn concentration is 1.3 × 1020 cm−3 About 90% of the in-diffused Zn atoms are located at tetrahedrally coordinated interstitial sites. The free carrier concentration is one order of magnitude lower than the number of substitutional Zn atoms. Precipitates are not found by the channeling technique. After heat treatment in a Zn-free atmosphere the surface zinc concentration decreases to 1 × 1019 cm−3 and nearly 90% of the diffused Zn atoms reside on regular lattice sites. The free carrier concentration increases from 2 × 1018 cm−3 after diffusion and before annealing to 9 × 1018 cm−3 after annealing. Aus PIXE (protoneninduzierte Rontgenemission)-Messunge kombiniert mit der Channeling-Technik werden Gitterplatzpositionen von Zn in InP untersucht. Die Gesamtzinkkonzentration betragt 1.3 × 1020 cm−3. Etwa 90% der eindiffundierten Zn-Atome werden auf tetraedrisch koordinierten Zwischengitterplatzen gefunden. Die Zahl der freien Ladungstrager ist eine Grosenordnung kleiner als die Anzahl der substitutionell eingebauten Zn-Atome. Prazipitate werden mit der Channeling-Technik nicht gefunden. Nach einem Temperschritt in Zn-freier Atmosphare fallt die Zn-Konzentration auf 1 × 1019 cm−3 und ungefahr 90% der diffundierten Zn-Atome werden auf regularen Gitterplatzen nachgewiesen. Die Konzentration der freien Ladungstrager steigt von 2 × 1018 cm−3 nach der Diffusion und vor dem Tempern auf 9 × 1018 cm−3 nach dem Tempern.

Positron lifetime measurements were used for studying decomposition during post-quench in situ annealing of binary Al-7.35 at.% Li and ternary Al-7.3 at.% Li-X (X=1.1 at.% Cu, 5.2 at.% Mg or 0.18 at.% Sc) alloys. A typical lifetime of 185+or-5 ps observed in Al-Li is attributed to coherent delta '(Al3Li) particles. In ternary alloys positrons show a strong response to the formation of semicoherent and incoherent phases such as T1(Al2LiCu) and Al2LiMg. Positron trapping in Al-Li-Sc is attributed to composite delta ' (Al3Li)/Al3Sc particles associated with vacancies. Quenched-in vacancies were detected in Al-Li-Sc and Al-Li-Mg but not in Al-Li-Cu and Al-Li.

The 14N hyperfine multiplets of low-7 rotational transitions of the E and Z isomers of HN = CH - C ≡ N, produced by flash pyrolysis from (CH3)2N -C ≡ N as precursor, were observed and analysed. The quadrupole coupling constants determined are (c-axis perpendicular to the molecular plane): The observed hfs multiplets were predicted with reasonable accuracy from RHF/6-311G** field gradients, once the latter had been scaled appropriately to compensate partly for the typical errors in the RHF-wave functions. The hitherto unmeasured 14N hyperfine multiplets of the related pyruvonitriles, H - N = C(CH3) - C ≡ N, are predicted.

The rotational Zeeman effect of H2F12C12C14N was observed at fields up to 20 kG (2 Tesla). The observed vibronic ground state expectation values for the molecular ^-values, the magnetic susceptibility anisotropies and the molecular electric quadrupole moments, all referred to the molecular principal inertia axes system, are: gaa= -0.03572 (11), gbb= -0.03438 (7), gcc= -0.03988 (6). 2ξaa- ξbb - ξcc = - 14.58 (10) • 10-6 erg/(G2 mole), 2ξaa- ξbb - ξcc= 1.60 (11) • 10-6 erg/(G2 mole), Qaa= -9.13 (6) DÅ, Qbb = 4M (7) DÅ, and Qcc = 4.96 (9) DÅ, respectively. The latter are in close agreement with the results of a restricted Hartree Fock self consistent field calculation with a basis of TZVP quality, which was carried out at the partial restructure determined earlier. Therefore the RHF/TZVP-value for the second electronic moment perpendicular to the heavy atom plane, 2 c|0)RHF, was used as additional input to predict the molecular bulk susceptibility and the individual components of the magnetic susceptibility tensor

A model is presented describing the relationship between chlorophyll fluorescence quenching and photoinhibition of Photosystem (PS) II-dependent electron transport in chloroplasts. The model is based on the hypothesis that excess light creates a population of inhibited PS II units in the thylakoids. Those units are supposed to posses photochemically inactive reaction centers which convert excitation energy to heat and thereby quench variable fluorescence. If predominant photoinhibition of PS IIα and cooperativity in energy transfer between inhibited and active units are presumed, a quasi-linear correlation between PS II activity and the ratio of variable to maximum fluorescence, FVFM, is obtained. However, the simulation does not result in an inherent linearity of the relationship between quantum yield of PS II and FVFM ratio. The model is used to fit experimental data on photoinhibited isolated chloroplasts. Results are discussed in view of current hypotheses of photoinhibition.

Dissociation energies for monomer evaporation from neutral and ionized benzene dimer, trimer, tetramer and pentamer are experimentally determined from the measured ionization potentials and the appearance potentials of the respective decay channels of each of the cluster ions. The results strongly support a stable triangular structure for the neutral benzene trimer. By contrast a sandwich-like structure for the trimer ion is concluded. In the latter case the main contribution to the binding energy is from charge-transfer resonance interaction rather than from induction forces of a localized charge with the neutral molecule. This conclusion is supported by the good agreement between the measured relative dependence of the binding energy on the cluster size and the results of Huckel calculations assuming a sandwich structure and a delocalized charge.

The zero field 14N-hfs-multiplets and the high-field Zeeman-hfs-multiplets of low-J rotational transitions of the title compounds were observed in a flash pyrolysis setup under high-resolution conditions. From the zero-field hfs patterns the 14N spin-rotation coupling constants and the 14N nuclear quadrupole coupling constants were obtained. From the high-field Zeeman-hfs-multiplets, the diagonal elements of the molecular g-tensor and the anisotropies in the diagonal elements of the molecular magnetic susceptibility tensor were determined and were used to derive the diagonal elements of the molecular electric quadrupole moment tensor. INDO calculations and restricted Hartree-Fock self consistent field calculations with a basis of TZVP quality were carried out at the experimental structures and critically compared to the experimental results

In this work the metastable decay of heterogeneous benzene/toluene, benzene/cyclohexane, and benzene/para‐difluorobenzene van der Waals cluster ions [(MiNk)+ with n=i+k

BIOPHYSICAL BASIS O F FLUORESCENCE EMISSION FROM CHLOROPLASTS . . . . .. . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . 314 Fluorescence as a Reaction Competing in the Deactivation of Excited Chlorophyll . . . . . . . . . . ... . . .. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 Lifetimes of Fluorescence . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . 317 Origin of Fluorescence Emission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1 Fluorescence of PS 11 and PS I at Ambient and Low Temperatures . . . . . . . . . . . . . . . . . . . 323 FLUORESCENCE INDUCTION AND PS II HETEROGENEITy 325 Fluorescence Transient from Fo to FM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325 The FI Level and Inactive PS11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... .... . .. . . . .. . . . . . . . . . 326 Fluorescence Induction in High Ught .. . . . . . . . . 327 Rise in the Presence of DCMU and a/{3 Heterogeneity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 FLUORESCENCE QUENCHING 329 Resolution of Quenching Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . ........ . .. . . . . . . . . . . . . . . 330 Mechanism of Energy·Dependent Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 1 Quenching Related t o State Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .. . ......... . . .. .. . . . . . . . 334 Photoinhibitory Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334 Further Quenching Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338 Physiological Aspects of Quenching . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 338 CONCLUSIONS AND PERSPECTiVES 341

The wall and Bloch-line motion at small magnetic fields in several garnet films has been investigated and coercive phenomena have been studied. Wall coercivity measurements have been carried out with various spatial resolutions. The coercivity curves show jumps and hysteresis effects at small observation windows. When increasing the observation window the measured curve represents the averaged response of all observed walls showing the mean value for the coercive field Hc. The coercive field of vertical Bloch lines has also been measured by directly observing the Bloch lines. Both measurements, wall and Bloch line, refer to local material inhomogeneities of the garnet films.

InxGa1−xAs/InP single quantum well structures are studied using Rutherford backscattering of energetic He+ ions. Optimal geometrical conditions are found by which the energy spectra of the backscattered ions clearly reflect the sequence of the layers. Especially, the determination of thickness and composition of the quantum well is shown and the required formulae are derived. The correlation between the measured well widths and the energetic shifts of the photoluminescence lines shows the typical quantum size effect. Mittels Rutherford-Ruckstreuung energiereicher He+-Ionen werden InxGa1−xAs/InP-Einfach-Quantengraben-Strukturen untersucht. Es werden optimale geometrische Bedingungen ermittelt, unter denen die Energiespektren der ruckgestreuten Ionen eindeutig die Schichtfolge widerspiegeln. Speziell werden die Bestimmung der Schichtdicke und der Zusammensetzung des Quantengrabens demonstriert und die erforderlichen Formeln abgeleitet. Die Korrelation der gemessenen Grabenbreiten mit den energetischen Verschiebungen der Photolumineszenzlinien zeigt den typischen Quantendimensions-effekt.

The generation of interface trap clusters and conducting microchannels at Fowler-Nordheim injection stress as a special effect of degradation of thin SiO2 films is investigated. The effect starts at a threshold field strength and tends to saturate. Threshold and saturation values depend on technological influences such as regime of thermal oxidation and microroughness of the substrate surfaces. From results obtained at both polarities different mechanisms of stress action may be supposed. Die Generation von Randzonentrapclustern und leitfahigen Mikrokanalen bei Fowler-Nordheim Injektionsstres als eine Art der Degradation dunner SiO2-Schichten wird untersucht. Der Effekt beginnt bei einer Schwellfeldstarke und strebt eine Sattigung an. Schwell- und Sattigungswerte sind von technologischen Einflussen, wie z. B. von der thermischen Oxydation und der Mikrorauhigkeit der Substratoberflache abhangig. Aus den Ergebnissen, die bei beiden Polaritaten erhalten werden, mus auf verschiedene Mechanismen der Streswirkung geschlossen werden.

In this work the appearance potentials for the metastable decay channel of a series of van der Waals dimer ions are presented. Ionization and metastable dissociation is achieved by resonance-enhanced two-photon absorption in a linear reflection time-of-flight mass spectrometer. From the appearance potentials the binding energy of the neutral dimers is obtained and from the additionally measured ionization potentials binding energies of the dimer cations are achieved. The contribution of charge transfer resonance interaction to the binding in cluster ions is evaluated by investigation of several homo-and heterodimers of aromatic components and the heterodimer benzene/cyclohexane as an example for a dimer consisting of an aromatic and a nonaromatic component.

Not least due to recent terrorist attempts to attack aviation traffic or mass transportation systems, e.g. in London in July 2005 or in August 2006, the secure and sensitive detection of liquid explosives is of major concern. Current presentation will deal with chemical and physical properties of possible liquid explosives used for military or civil applications or misused in improvised explosive devices. Besides a short look at state-of-the-art explosives detection techniques, this presentation addresses e.g. Raman spectroscopic and gas Chromatographic measurements of typical liquid explosives and flammables. General challenges for improved detection techniques and the applicability of the addressed analytical techniques will be discussed in relation to different detection scenarios.

Slow metastable fragmentation of benzene/toluene and benzene/para‐difluorobenzene clusters is observed in a newly developed linear reflectron time‐of‐flight mass spectrometer after two‐photon ionization. The breakdown of the metastable intensity with decreasing two‐photon energy is measured and yields the appearance potential for the main dissociation channels of the homo‐ and the heterodimers. Based on these values, the dissociation energies of the neutral dimers are obtained and shown to be consistent with the changes of the polarizability and dipole moment of the components. In addition, from the appearance potentials and the measured ionization potentials, the dissociation energies of the charged dimer clusters are found. The binding energies of the heterocluster ions and the para‐difluorobenzene homodimer ion are smaller than the respective binding energies in the benzene and toluene homodimer ions. This is explained by a larger contribution of charge transfer resonance interaction to the binding energy of the latter homodimer ions. On the basis of these results we present an energetic scheme for prediction of the dissociation pathways of the trimer ions in agreement with the measured results.

Fast, selective, sensitive and inexpensive detection techniques are highly required concerning the identification of planned terrorist attacks in- volving explosive, chemical or biological materials. State of the art are cost intensive equipments used e.g. in airport portal systems or swapping techniques (Imaging by X-ray, TeraHz-, MMwave, NQR, neutron activation techniques, electronic noses, IMS). We propose the development of substance specific low cost sensors, which can be installed as self reporting sensors in containers, compartments, wagons etc., used as hand held systems or sniffing devices which analyse the content of explosives in the gas phase. The basic sensor concept uses mass-sensitive devices coated with mole- cularly imprinted polymers (MIP). The components are cheap promising low- cost detection devices which could be applied for the passive as well as active sensing of explosives like TNT, DNT or TATP at short-range distances of about one meter. In the case of active sampling the MIP sensor will be combined with a suitable air-sucking system. Molecular imprinted polymers (MIPs) are highly cross-linked polymers. Like enzymes they possess a high affinity and selectivity for the adsorption of a special target substance (template molecule) which is present only during the MIP-synthesis and is afterwards extracted. This yields to a finished polymer with special and very selective binding sites for the former template. MIPs are very inexpensive, rapid to synthesise and they are already applied as substance specific solid phase extraction materials in the liquid phase. Preliminary results /1/ of synthesized particulate TNT-specific MIPs showed the effective adsorption capability of the material for TNT vapours. Moreover first experiments using direct UV-initiated polymerisation of TNT- MIPs produced thin films which can be used in combination with different sensor materials.

We report on multi-MeV ion beam generation from the interaction of a 10 TW, 400 fs, 1.053 μm laser focused onto thin foil targets at intensities ranging from 1017 to 1019 W/cm2. Ion beam characteristics were studied by changing laser intensity, the preformed plasma scale-length and target material initial conductivity. We manipulated the proton beam divergence by using shaped targets. We observed nuclear transformation induced by high-energy protons and deuterons. A fully relativistic two-dimensional particle-in-cell simulation modeled energetic ion generation. These simulations identify the mechanism for the hot electron generation at the laser-plasma interface. Comparison with experiments sheds light on the dependence of ion-energy on preplasma scale length and solid density plasma thickness as well as relates ion energies for multi-species plasma.

The long-term graft function after withdrawal of steroids from maintenance immunosuppression was analyzed in 98 kidney recipients (59 on cyclosporin monotherapy, 39 on cycloporin plus azathioprine) who had not developed an early rejection episode when prednisolone was discontinued. Seven years after steroid withdrawal the probability of an increase in serum creatinine (>20% of baseline levels) was 51%. The increase in creatinine was associated with sclerosing arteriopathy as a marker of chronic rejection in 29 of 43 graft biopsies. The addition of azathioprine had no, effect on the stability of long-term graft function and did not influence the 7-year graft survival rate in this highly selected group of patients.

Involvement of the dopaminergic system has been suggested in patients suffering from attention deficit hyperactivity disorder (ADHD) since the symptoms can be successfully treated with methylphenidate, a potent blocker of the dopamine transporter (DAT). This study reports the findings on the status of the DAT in adults with ADHD before and after commencement of treatment with methylphenidate, as measured using [99mTc]TRODAT-1. Seventeen patients (seven males, ten females, aged 21-64 years, mean 38 years) were examined before and after the initiation of methylphenidate treatment (3x5 mg/day). All subjects were injected with 800 MBq [99mTc]TRODAT-1 and imaged 3 h p.i. Single-photon emission tomography (SPET) scans were acquired using a triple-headed gamma camera. For semiquantitative evaluation of the DAT, transverse slices corrected for attenuation were used to calculate specific binding in the striatum, with the cerebellum used as background [(STR-BKG)/BKG]. Data were compared with an age-matched control group. It was found that untreated patients presented with a significantly increased specific binding of [99mTc]TRODAT-1 to the DAT as compared with normal controls [(STR-BKG)/BKG: 1.43+/-0.18 vs 1.22+/-0.06, P

In recent studies with tropical plants, photoinhibition of photosystem II (PS II) (as indicated by a decline in the dark-adapted ratio of variable to maximum Chl fluorescence yield, FV/FM) has been observed to occur during direct sun exposure of canopy sun leaves of tall trees (1) and of plants growing in treefall gaps of the tropical forest (2, 3). Recovery from photoinhibition under low-light was found to depend on conversion of zeaxanthin to violaxanthin via the xanthophyll cycle (fast recovery, lasting about 1 h) and on turnover of the D1 protein of PS II (slow recovery, lasting several h) (3–5).