Search

In situ cosmogenic nuclides are an important tool for quantifying landscape evolution and dating fossil-bearing deposits in the Cradle of Humankind (CoH), South Africa. This technique mainly employs cosmogenic 10-Beryllium (Be-10) in river sediments to estimate denudation rates and the ratio of 26-Aluminium (Al-26) to Be-10 (Al-26/Be-10), to constrain ages of sediment burial. Here, we use Be-10 and Al-26 concentrations in bedrock and soil above the Rising Star Cave (the discovery site of Homo naledi) to constrain the denudation rate and the exposure history of soil on the surface. Apparent Be-10-derived denudation rates obtained from pebble- to cobble-sized clasts and coarse-sand in soil (on average 3.59 +/- 0.27 m/Ma and 3.05 +/- 0.25 m/Ma, respectively) are 2-3 times lower than the bedrock denudation rates (on average 9.46 +/- 0.68 m/Ma). In addition, soil samples yield an average Al-26/Be-10 ratio (5.12 +/- 0.27) that is significantly lower than the surface production ratio of 6.75, which suggests complex exposure histories. These results are consistent with prolonged surface residence of up to 1.5 Ma in vertically mixed soils that are up to 3 m thick. We conclude that the Be-10 concentrations accumulated in soils during the long near-surface residence times can potentially cause underestimation of single-nuclide (Be-10) catchment-wide denudation rates in the CoH. Further, burial ages of cave sediment samples that consist of an amalgamation of sand-size quartz grains could be overestimated if a pre-burial Al-26/Be-10 ratio calculated from the surface production is assumed.

We describe the reversible photoactivation of the acid sensitive ligand-gated ion channel ASIC2a, a mammalian channel found throughout the central and peripheral nervous systems that is associated with vision and pain. We have also shown the activation of GLIC, an acid-sensitive prokaryotic homolog of the nicotinic acetylcholine receptor. Photoactivation was achieved using visible-light irradiation of a newly synthesized water-soluble merocyanine photoacid, 1, which was designed to remove adverse channel blocking effects of a related system. Activation of ASIC2a and GLIC occurs reversibly, in a benign manner, and only upon irradiation. Further studies using transient absorption spectroscopy have shown that protonation of a colorimetric base occurs rapidly (ca. 100 µs) after excitation of 1. These results demonstrate that irradiation of 1 can induce rapid, local pH changes that can be used to investigate both biological and chemical proton transfer reactions.

Prior to 1950, the consensus was that biological transformations occurred in two-electron steps, thereby avoiding the generation of free radicals. Dramatic advances in spectroscopy, biochemistry, and molecular biology have led to the realization that protein-based radicals participate in a vast array of vital biological mechanisms. Redox processes involving high-potential intermediates formed in reactions with O_2 are particularly susceptible to radical formation. Clusters of tyrosine (Tyr) and tryptophan (Trp) residues have been found in many O_2-reactive enzymes, raising the possibility that they play an antioxidant protective role. In blue copper proteins with plastocyanin-like domains, Tyr/Trp clusters are uncommon in the low-potential single-domain electron-transfer proteins and in the two-domain copper nitrite reductases. The two-domain muticopper oxidases, however, exhibit clusters of Tyr and Trp residues near the trinuclear copper active site where O_2 is reduced. These clusters may play a protective role to ensure that reactive oxygen species are not liberated during O_2 reduction.

Individuals with human immunodeficiency virus (HIV) have an increased risk of developing health problems, including some that are life threatening. Today, dental treatment for the population with a positive HIV diagnosis (HIV+) is comprehensive. There are limited reports on the outcomes of intraoral surgical therapy in patients with HIV, such as crown lengthening surgery (CLS) with osseous recontouring. This report investigates the outcome of CLS procedures performed at an urban dental school in a population of individuals with HIV. Specifically, this retrospective clinical analysis evaluates the healing response after CLS.Paper and electronic records were examined from the year 2000 to the present. Twenty-one individuals with HIV and immunosuppression, ranging from insignificant to severe, underwent CLS. Pertinent details, including laboratory values, medications, smoking history/status, and postoperative outcomes, were recorded. One such surgery is described in detail with radiographs, photographs, and a videoclip.Of the 21 patients with HIV examined after CLS, none had postoperative complications, such as delayed healing, infection, or prolonged bleeding. Variations in viral load (48 to 40,000 copies/mL), CD4 cell count (126 to 1,260 cells/mm(3)), smoking (6 of 21 patients), platelets (130,000 to 369,000 cells/mm(3)), and neutrophils (1.1 to 4.5 × 103 /mm(3)) did not impact surgical healing. In addition, variations in medication regimens (highly active anti-retroviral therapy [18]; on protease inhibitors [1]; no medications [2]) did not have an impact.The results of this retrospective analysis show the absence of postoperative complications after CLS in this population with HIV. Additional investigation into this area will help health care practitioners increase the range of surgical services provided to this group of patients.

Metallic hollow sphere structures (MHSS) form a relatively new group of advanced composite materials characterised by high geometry reproduction leading to stable mechanical and physical properties. The MHSS combine the well-known advantages of cellular metals in terms of their high ability for energy adsorption, good damping behaviour, excellent heat insulation and high specific stiffness without major scattering of their material parameters. A combination of these properties opens a wide field of potential applications, e. g. in automotive (crash absorber) and aerospace industry (sandwich panels). Various joining technologies such as sintering, soldering and adhering can be used to assemble single metallic hollow spheres to interdependent structures and allow different macroscopic properties. In this study the behaviour of Metallic Hollow Spheres Structures due to structure-borne sound is investigated. Longitudinal vibrations within a rod serve as an example. Experimental data are compared with analytical solutions and results computed by the finite element method. Metallische Hohlkugelstrukturen (MHKS) bilden eine relativ neue weiterentwickelte Gruppe der Verbundwerkstoffe, die sich durch ihre geometrische Reproduzierbarkeit und ihre konstanten mechanischen und physikalischen Eigenschaften auszeichnet. Die MHKS vereinen die bekannten Vorteile der zellularen Metalle bezuglich ihres grosen Energieabsorptionsvermogens, ihres Dampfungsverhaltens und ihrer exzellenten Warmeisolation und hohen spezifischen Festigkeit ohne grose Streuung der Materialkennwerte. Eine Kombination dieser Eigenschaften eroffnet ein weites Feld von potenziellen Anwendungen, z. B. im Fahrzeugbau (Crash Absorber) und in der Luftfahrtindustrie (Sandwich Panel). Ein Verbund aus einzelnen Hohlkugeln lasst sich mit verschiedenen Verbindungstechnologien, wie Sintern, Loten oder Kleben realisieren und ermoglicht verschiedene makroskopische Eigenschaften. In der vorliegenden Arbeit ist das Korperschallverhalten untersucht worden. Longitudinale Schwingungen in einem Stab dienen als Beispiel. Die Versuchsergebnisse werden mit analytischen Losungen und FE-Simulationsergebnissen verglichen.

The [Re(I)(CO)(3)(4,7-dimethyl-1,10-phenanthroline)(histidine-124)(tryptophan-122)] complex, denoted [Re(I)(dmp)(W122)], of Pseudomonas aeruginosa azurin behaves as a single photoactive unit that triggers very fast electron transfer (ET) from a distant (2 nm) Cu(I) center in the protein. Analysis of time-resolved (ps-μs) IR spectroscopic and kinetics data collected on [Re(I)(dmp)(W122)AzM] (in which M=Zn(II), Cu(II), Cu(I); Az=azurin) and position-122 tyrosine (Y), phenylalanine (F), and lysine (K) mutants, together with excited-state DFT/time-dependent (TD)DFT calculations and X-ray structural characterization, reveal the character, energetics, and dynamics of the relevant electronic states of the [Re(I)(dmp)(W122)] unit and a cascade of photoinduced ET and relaxation steps in the corresponding Re-azurins. Optical population of [Re(I)(imidazole-H124)(CO)(3)]→dmp (1)CT states (CT=charge transfer) is followed by around 110 fs intersystem crossing and about 600 ps structural relaxation to a (3)CT state. The IR spectrum indicates a mixed Re(I)(CO)(3),A→dmp/π→π(*)(dmp) character for aromatic amino acids A122 (A=W, Y, F) and Re(I)(CO)(3)→dmp metal-ligand charge transfer (MLCT) for [Re(I)(dmp)(K122)AzCu(II)]. In a few ns, the (3)CT state of [Re(I)(dmp)(W122)AzM] establishes an equilibrium with the [Re(I)(dmp(.-))(W122(.+))AzM] charge-separated state, (3)CS, whereas the (3)CT state of the other Y, F, and K122 proteins decays to the ground state. In addition to this main pathway, (3)CS is populated by fs- and ps-W(indole)→Re(II) ET from (1)CT and the initially "hot" (3)CT states, respectively. The (3)CS state undergoes a tens-of-ns dmp(.-)→W122(.+) ET recombination leading to the ground state or, in the case of the Cu(I) azurin, a competitively fast (≈30 ns over 1.12 nm) Cu(I)→W(.+) ET, to give [Re(I)(dmp(.-))(W122)AzCu(II)]. The overall photoinduced Cu(I)→Re(dmp) ET through [Re(I)(dmp)(W122)AzCu(I)] occurs over a 2 nm distance in50 ns after excitation, with the intervening fast (3)CT-(3)CS equilibrium being the principal accelerating factor. No reaction was observed for the three Y, F, and K122 analogues. Although the presence of [Re(dmp)(W122)AzCu(II)] oligomers in solution was documented by mass spectrometry and phosphorescence anisotropy, the kinetics data do not indicate any significant interference from the intermolecular ET steps. The ground-state dmp-indole π-π interaction together with well-matched W/W(.+) and excited-state [Re(II)(CO)(3)(dmp(.-))]/[Re(I)(CO)(3)(dmp(.-))] potentials that result in very rapid electron interchange and (3)CT-(3)CS energetic proximity, are the main factors responsible for the unique ET behavior of [Re(I)(dmp)(W122)]-containing azurins.

The reduction of N&V (noise and vibration) is a progressively more important objective for designers of various engineering applications. When a series of physical and mechanical requirements are touched, classic materials reach their limits. Cellular metals with their great diversity of properties open up new vistas. Metallic hollow sphere structures (MHSS) feature a new group of advanced composite materials characterised by high geometrical reproducibility leading to stable properties. In the scope of this study, vibrational analysis of sintered metallic hollow sphere structures is performed. The objective is a description of the dynamic response by numerical simulation, A detailed finite element model would exceed available resources. Therefore, a proper model with special descriptions for hollow spheres and interconnections has been developed and is presented in detail. Numerical results are compared with vibrations measured by laser scanning vibrometer and analytical analysis.

Die magnetischen Verluste, welche nach dem phanomenologischen Modell von Landau Lifschitz betrachtet werden, konnen unter Nutzung der mikroskopischen und makroskopischen Werkstoffeigenschaften entwickelt werden. Jedoch beziehen sich diese Betrachtungen auf kristalline Schichten und nicht auf reale granulare Strukturen. Granulare Strukturen sollen [ 2 ] eine hohere Absorption der elektromagnetischen Energie realisieren konnen als kristalline Schichten. Ziel dieser Arbeit ist es ein Simulationsmodell unter Nutzung realer amorpher und kristalliner Schichteigenschaften aufzubauen und einen Designhinweis zur Entwicklung einer Schicht hin zu hoheren Absorptionen aufzuzeigen. Die erhohte Absorption der granularen Nanomaterialien soll in elektromagnetischer Vertraglichkeitsanwendungen (EMV) fur Leitungen und Schichten fur Entstorfolien eingesetzt werden. Eine RF – Materialanalyse, eine AFM - Schichtanalyse und EMV - Analyse schliest den Kreis zum Materialdesign und EMV zur Industrieanwendung als Absorbermaterial bzw. Entstormaterial. Granular magnetic ultrathinthin multilayer films Fe/ FeO on Al substrates, modelling of a 1 D granulare thin film for EMC applications Hematite ferrite thin films in granular structures have attracted much attention as materials with unique proper ties. One of these properties is enhanced microwave absorption for a good EMC application. This gives a possibility to absorption electro magnetic covers ( EMC ) of cable application with ultrathin thickness and granular structure. The Electromagnetic Compatibility absorption of granular Ferrite polycristalline sample is 6 - 7 dB in the GH z - range.

In the preceding text the author proves the availability and validity of the generic name Dermestoides J. C. SCHAEFFER for an European species classified till now commonly with the American genus Orthopleura SPIN. Provisions of the International Code of Zoological Nomenclature in question are cited and compared with the nomenclatural case dealt with. Generic names recently published for the taxon discussed (Aporthopleura BARR, 1977, Eurenoplium ŽIROVNICKÝ, 1977) are synonymized with Dermestoides. Catalogues given (including some old citations omitted in CORPORAALS Catalogue). Two additions are appended: the first giving some information on morphology and variability, the second one discussing the status of the Syrian species Orthopleura funebris FAIRMAIRE.

New genus Canariclerus gen. n. for reception of Clerus paivae Wollaston, 1862, is established. The species till now classified with the genera Clerus and Thanasimus. Differential diagnosis of Canariclerus and Thanasimus (as the characters of both those, not of Clerus, however, in the only hitherto now existing Schenkling's key to world genera parallelled), description of genus, redescription of the typespecies, discussion and photograph of the plesiotype are the parts of the paper.

The subspecies mentioned in the headline is promoted to a proper species. Differential diagnosis and diagrammatic pictures of T. crabroniformis and T. hidalgo, and a realistic picture, unpublished till now, of male copulatory organ of the latter species as well as discussion on distribution of T. hidalgo are given in a following text.

The taxonomic position of the species Orthopleura funebris Fairmaire, 1892, is re-classified. Incongruence with any of hitherto known enopliine genera was ascertained and a new genus Syriopelta gen. n. was validized (O. funebris type-species). Differential diagnosis, description involving the wing morphology compared with wing structures of related genera, morphology, results of microscopical examination of tarsi (see below) as well as synonymy of generic names are given. The holotype female of type-species was dissected and detailed type redescription involving the morphology of microscopically examined ovipositor as well as catalogues are given. In the section Discussion the atypical structure of the tarsi of holotype ‘in toto’ is discussed, tarsi substantiated as fully enopliine and their shape cleared up as artificial by means of direct model comparison of the type-species of genera being the types of two subfamilies of Cleridae peltatae, i. e. Enoplium serraticorne (Enopliinae) and Tarsostenus univittatus (Tarsosteninae).

In the course longer than one and half century both species classified with the genus Denops have been conjecturally considered once for two valid species, another time for identical ones. Both these contradictory viewpoints were always based upon nothing but subjective impression of individual students as colour pattern was the only distinguishing criterion. Virtual morphological analysis, decisive for the taxonomic classification, was never done. Thus the following paper represents the first morphological analysis based upon examination of the male and female terminalia. Demonstrable identity of both clean-cut chromatic types traditionally identified as D. albofasciatus and D. longicollis as well as of ascertained intermediate chromatic types was proved and D. longicollis was synonymized as a synonym of D. albofasciatus.

This communication deals with a new representative of apterous Cleridae from Pe-Yen-Tsin, Yunnan Province of China, Ekisius vitreus gen. n., sp. n. The only hitherto known specimen, holotype female, is described on the basis of surface characters as well as dissected terminalia, and discussed.

Metal hollow sphere structures represent a new material group. Within the design progress classical materials are replaced by these new class when a series of physical / mechanical requirements are touched. Typical requirements are related to strength, stiffness, electrical or thermal conductivity. In this study the vibration behaviour is looked at in detail. The overall objective is a description of the dynamic response by numerical simulation. An extraordinary detailed FEM model would exceed available resources. Therefore a proper model with special descriptions for the hollow spheres, the matrix material and the interconnections has to be defined. This paper provides a proper FEM model. Results are compared with vibrations measured by a laser scanning vibrometer.

The aims of the study were to verify the longterm effect of time on viral clearance in hepatitis C virus (HCV) patients and to find out factors possibly associated with disease progression. A total of 1641 patients recruited from eight European centres in 1996-1.997 were re-analysed 5-7 years after inclusion. The occurrence of decompensated cirrhosis, hepatocellular carcinoma (HCC) and liver transplantation was analysed in relation to different host and viral factors. Ninety-three per cent of the HCV patients who had cleared the virus (spontaneously or after antiviral therapy) remained HCV-RNA-negative during follow up and may be considered as 'cured'. Among patients who were sustained responders at inclusion, 2.3% developed liver complications during follow up, and 31% of non-responders did. Advanced age at infection and presence of the human leucocyte antigen (HLA) DRBI*1201-3 allele were possibly associated with a higher rate of progression to decompen- sated cirrhosis or HCC. Decompensated cirrhosis might be further associated with male gender, non-response to previous therapy, and lack of FILA DRBI*1301 allele, whereas HCC seems to be associated with the presence of the HLA DQ02 allele. Long-term follow up of HCV patients indicates that virological response persists over time and is associated with a very low incidence of liver complications. Advanced age at inclusion. advanced age at infection, viral genotype 1, non-response to previous therapy and possibly some specific HLA alleles are factors independently associated with a faster rate of progression towards liver complications. The large proportion of patients lost to follow up stresses the need for a strengthened and optimized management of HCV patients. (Less)

Spin-resolved single-electron tunneling in GaAs/AlGaAs double-barrier resonant tunneling structures is used to investigate the spin-splitting of fully quantized electronic states. With the use of magneto-tunneling spectroscopy we evaluated the Lande g -factor of GaAs quantum dots of different confinement strengths. We observe with increasing confinement a shift of the Lande-factor from the bulk GaAs-value towards positive values. Our results are compared to a multiband-k·p-calculation. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A brief introduction into the progress of the analysis of the electron kinetics and the self-consistent description of inhomogeneous and nonstationary plasmas is given. The spectrum of problems treated by electron kinetic studies as well as by the overall description of non-isothermal plasmas is briefly characterized. Main aspects of the analyses are outlined and the progress reached in recent years in the framework of the collaborative research activities of the Sonderforschungsbereich 198 “Kinetics of partially ionized plasmas” is illustrated by topical kinetic study and self-consistent modelling results of some selected problems. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We devise a fast fraction-free algorithm for the computation of the triangular factorization of Bernstein–Bezoutian matrices with entries over an integral domain. Our approach uses the Bareiss fraction-free variant of Gaussian elimination, suitably modified to take into account the structural properties of Bernstein–Bezoutian matrices. The algorithm can be used to solve problems in algebraic geometry that arise in computer aided geometric design and computer graphics. In particular, an example of the application of this algorithm to the numerical computation of the intersection points of two planar rational Bezier curves is presented. Copyright © 2005 John Wiley & Sons, Ltd.

The mobility of hydrophobic organic compounds (HOCs) in soils can be influenced by the presence of dissolved organic matter (DOM). While numerous studies have determined interactions of HOCs with humic and fulvic acids, only few data exist on the partitioning of HOCs to natural, non-fractionated DOM as it occurs in soil solutions. In this study, DOM was extracted from 17 soil samples with a broad range of chemical and physical properties, originating from different land uses. The partition coefficients of pyrene to DOM were determined in all soil extracts and for two commercial humic acids using the fluorescence quenching method. For the soil extracts, log K DOC values ranged from 3.2 to 4.5 litres kg -1 . For the Aldrich and Fluka humic acids, log K DOC was 4.98 and 4.96 litres kg -1 , respectively, thus indicating that they are not representative for soil DOM. After excluding these two values, the statistical analysis of the data showed a significant negative correlation between log K DOC and pH. This was also shown for one sample where the pH was adjusted to values ranging from 3 to 9. A multiple regression analysis suggested that ultraviolet absorbance at 280nm (an indicator for aromaticity) and the E4:E6 ratio (an indicator for molecular weight) had additional effects on log K DOC . The results indicate that the partitioning of pyrene to DOM is reduced at alkaline pH, probably due to the increased polarity of the organic macromolecules resulting from the deprotonation of functional groups. Only within a narrow pH range was the K DOC of pyrene mainly related to the aromaticity of DOM.

Employing fluorescence energy transfer kinetics, we have shown that substantial populations of compact molecules are present in GuHCl-denatured CX-dansyl-labeled (X = 39, 85, 102) S. cerevisiae iso-1 cytochrome c. Fully 40% of unfolded molecules are in compact conformations in the C39 protein.

A brief introduction into the progress of the analysis of the electron kinetics in spatially one- and two-dimensional steady-state plasmas and in spatiotemporal transition processes of spatially one-dimensional plasma configurations is given. The wide spectrum of the involved kinetic problems is briefly characterized, main aspects of its kinetic studies are outlined and the progress reached in recent years is illustrated by the kinetic study and deduced results of some selected problems.

The advent of high throughput molecular technologies has led to an expectation that breeding programs will use marker-trait associations to conduct marker-assisted selection (MAS) for traits. Many challenges exist with this molecular breeding approach for so-called complex traits. A major restriction to date has been the limited ability to detect and quantify marker-trait relationships, especially for traits influenced by the effects of gene-by-gene and gene-by-environment interactions. A further complication has been that estimates of quantitative trait loci (QTL) effects are biased by the necessity of working with a limited set of genotypes in a limited set of environments, and hence the applications of these estimates are not as effective as expected when used more broadly within a breeding program. The approach considered in this paper, referred to as the Mapping As You Go (MAYG) approach, continually revises estimates of QTL allele effects by remapping new elite germplasm generated over cycles of selection, thus ensuring that QTL estimates remain relevant to the current set of germplasm in the breeding program. Mapping As You Go is a mapping-MAS strategy that explicitly recognizes that alleles of QTL for complex traits can have different values as the current breeding material changes with time. Simulation was used to investigate the effectiveness of the MAYG approach applied to complex traits. The results indicated that greater levels of response were achieved and these responses were less variable when estimates were revised frequently compared with situations where estimates were revised infrequently or not at all.

The interpretation of the anode current characteristics obtained in the famous Franck-Hertz experiment of 1914 led to the verification of Bohr's predictions of quantised atomic states. This fundamental experiment has been often repeated, and nowadays is generally part of the curriculum in modern physics education. However, the interpretation of the experiment is typically based upon significant simplifying assumptions, some quite unrealistic. This is the case especially in relation to the kinetics of the electron gas, which is in reality quite complex, due mainly to non-uniformities in the electric field, caused by a combination of accelerating and retarding components. This non-uniformity leads to a potential energy valley in which the electrons are trapped. The present state of understanding of such effects, and their influence upon the anode characteristics, is quite unsatisfactory. In this article a rigorous study of a cylindrical Franck-Hertz experiment is presented, using mercury vapour, the aim being to reveal and explain what really happens with the electrons under realistic experimental conditions. In particular, the anode current characteristics are investigated over a range of mercury vapour pressures appropriate to the experiment to clearly elaborate the effects of elastic collisions (ignored in typical discussions) on the power budget, and the trapping of electrons in the potential energy valley.

Zusammenfassung: Ziel der Arbeit war es, den Einflus hoher Jodgaben in Form eines parenteral verabreichten Rontgenkontrastmittels auf Veranderungen des Lipid- und Schilddrusenhormonstatus sowie des pro-/antioxidativen Gleichgewichts von Kurpatienten zu untersuchen. Dazu wurden 29 Patienten mit vergleichbaren Indikationen, die sich einer Koronarangiographie unterziehen musten, ausgewahlt und deren Blutparameter vor und nach der angiographischen Masnahme bestimmt. Es fanden sich keine nachweisbaren Veranderungen der Schilddrusenparameter f-T3, f-T4 und TSH nach der Angiographie. Im Falle der Enzymaktivitaten zeigten sich fur die Schutzenzyme SOD und GSHPX keine Veranderungen, wahrend die Peroxid- und die MDA-Konzentrationen nach der Angiographie signifikant erhoht waren. Dementsprechend nahmen der gesamt-antioxidative Status (TAS) und der Vitamin-E-Spiegel im Serum signifikant ab. Insgesamt sprechen die Ergebnisse fur eine masige Verschlechterung des antioxidativen Schutzpotentials durch das stark jodhaltige Kontrastmittel. Effects of High Iodine Doses Given Parenterally as Contrast Medium on Parameter of the Pro/Antioxidative Balance Summary: The aim of this study was to investigate effects of high iodine doses given parenterally as contrast medium on parameters of lipid status and thyroid hormon status as well as on parameters of the pro/antioxidative balance of spa patients. 29 patients with a comparable indication who had to undergo an angiogaphy were chosen. The blood paramet­ers of these patients were determined before and after the angiographic treatment. No provable changes of the thyroid parameters f-T3, f-T4 and TSH were found after the angiography. In case of enzyme activities, the protective enzymes SOD and GSHPX showed no changes, while the concentrations of peroxides and MDA were increased significantly. Corresponding to this, the total antioxidative status and the vitamin E level decreased significantly. Altogether these results stand for a moderate deterioration of the antioxidative protective potential by the highly iodine containing contrast medium.

Customers nowadays regard the noise and vibration behavior as an essential product property. Cellular character materials, in particular hollow sphere structures, are predestined to absorb sound in a very efficient manner due to their cellular character. Depending on the constituent material, the geometric parameters like the diameter of the spheres, the thickness of the walls and the assembling schema of single spheres, the absorption coefficient can be reduced to very low levels. In contrast to other cellular materials, the frequency and bandwidth can actively be influenced by the variation of the above mentioned parameters. In order to predict the acoustic behavior of a structure, FE or CFD analyses are used as standard tools. In addition, there exist some parameter based models, e.g. the BIOT theory, which characterizes the absorption, transmission and reflection coefficients using a few macroscopic parameters. Within this contribution, the acoustic properties of hollow sphere structures are investigated by a so-called virtual material laboratory GeoDict (by Math2Market GmbH, originally by the Fraunhofer Institute for Industrial Mathematics). The results for the absorption and reflection coefficients are compared to those gained by classical analysis methods and experiments based on Kundt's tube. Das Gerausch- und Schwingungsverhalten ruckt heutzutage mehr und mehr als ein entscheidendes Kaufkriterium fur die Konsumenten in den Mittelpunkt. Aufgrund ihres makroskopischen Aufbaus eignen sich zellulare Werkstoffe, im Besonderen Hohlkugelstrukturen, hervorragend als hocheffiziente Schallabsorber. Abhangig vom Ausgangswerkstoff, dem Herstellungsverfahren sowie den geometrischen Parametern, wie beispielsweise dem Kugeldurchmesser und der Wanddicke, lassen sich die Absorptionskoeffizienten nahezu beliebig variieren. Vergleicht man Hohlkugelstrukturen mit anderen zellularen Werkstoffen, so lasst sich bei diesen sowohl die Frequenz wie auch der Frequenzbereich, in welchem sie herausragende akustische Eigenschaften besitzen, aktiv durch eine Variation der Parameter anpassen. Zur Vorhersage des akustischen Verhaltens von Werkstoffen finden ublicherweise FE- oder CFD-Simulationen Verwendung. Des Weiteren besteht die Moglichkeit, mit Hilfe von parametrischen Modellen, wie beispielsweise der Biot-Theorie, die Schallabsorption, Transmission und Reflexion mit einigen wenigen makroskopischen Parametern zu beschreiben. Im Rahmen dieses Beitrages werden die akustischen Eigenschaften von Hohlkugelstrukturen mit dem sogenannten virtuellen Materiallabor GeoDict (jetzt Math2Market GmbH, ursprunglich Fraunhofer ITWM) berechnet. Die aus diesen Daten berechneten Ergebnisse des Absorptions- und Reflexionskoeffizienten werden mit denen der experimentellen Untersuchungen, die mit dem Kundt'schen Rohr bestimmt wurden, verglichen.

Splitting water to hydrogen and oxygen is a promising approach for storing energy from intermittent renewables, such as solar power. Efficient, scalable solar-driven electrolysis devices require active electrocatalysts made from earth-abundant elements. In this mini-review, we discuss recent investigations of homogeneous and heterogeneous hydrogen evolution electrocatalysts, with emphasis on our own work on cobalt and iron complexes and nickel-molybdenum alloys.

The electron density in the positive column of DC glow discharges has been determined by means of an improved method of the microwave diagnostics. This method is based on the measurement of both the resonance frequency shift of the resonator cavity and the change of the inverse resonator quality. It makes explicit use of the associated phase delay between the microwave field and the induced HF electric current. To evaluate the applicability of the method and of a simplified version of it to complex molecular mixture plasmas, the electron density in CO 2 /CO/O 2 mixture plasmas has been measured for larger ranges of gas pressure and discharge current. The applicability check is made by a comparison between measured and calculated results for the phase delay. The good agreement between experimental and theoretical results supplies evidence for a far-reaching applicability of the simplified version of the improved microwave diagnostics method that allows the determination of the electron density without detailed information about the plasma composition and the electron energy distribution. The theoretical determination of the phase delay has been done by solving the time-dependent electron Boltzmann equation. Two different techniques have been employed to solve this kinetic equation. In particular, the conventional two-term treatment has been analysed with respect to its suitability to molecular gas mixtures and has been found to be sufficient for the determination of the phase delay.

Summary: Diagnosing a coupled system with linear inverse modelling (LIM) can provide insight into the nature and strength of the coupling. This technique is applied to the cold season output of the GFDL GCM, forced by observed tropical Pacific SSTs and including a slab mixed layer ocean model elsewhere. It is found that extratropical SST anomalies act to enhance atmospheric thermal variability and diminish barotropic variability over the east Pacific in these GCM runs, in agreement with other theoretical and modelling studies. North-west Atlantic barotropic variability is also enhanced. However, all these feedbacks are very weak. LIM results also suggest that North Pacific extratropical SST anomalies in this model would rapidly decay without atmospheric forcing induced by tropical SST anomalies.

New subspecies, Tilloidea unifasciata elbursiaca subsp. n. described. The new taxon is easily distinguishable from its nominate subspecies by its bodyform and colour pattern of elytra. Differential diagnosis, description, discussion, and diagrammatic pictures of both subspecies are given.

Oxidieren und reduzieren kann man die Hamgruppe im aktiven Zentrum von Cytochrom P450cam mit dem Photosensibilisator [Ru(bpy)3]2+ (bpy=2,2′-Bipyridin). Dieser ist uber einen Alkyl-Spacer mit einer Gruppe verknupft, die eine hohe Affinitat zur Ham-Bindungstasche aufweist (siehe Bild). Die Richtung des photoinduzierten Ladungstransfers last sich durch geeignete Loscher steuern; die neuen Oxidationszustande werden schnell gebildet (0.1 ms) und haben eine Lebensdauer von ca. 100 ms.

Using a new method for solving the time-dependent electron Boltzmann equation in higher order accuracy, studies of the temporal behaviour of electrons in weakly ionized, collision-dominated plasmas under the action of rf fields have been performed. The method is based upon a multi-term approximation of the Legendre polynomial expansion of electron velocity distribution function and is applied to investigate the established periodic behaviour of the electron velocity distribution in helium, argon and CO plasmas. The results obtained in various approximation orders are discussed. The analysis has shown that the simplified treatment using only two terms of the velocity distribution expansion can fail in several conditions. In general, the four-term approximation gives already a good representation of the convergent solution of the electron Boltzmann equation at each instant of the rf period. The discrepancies between two-term and convergent results are found to depend sensitively on the specific atomic data, in particular on the magnitude of the various electron collision cross sections involved. Furthermore, the results obtained in the multi-term approximation are compared with corresponding ones obtained by accurate Monte Carlo simulations. Very good agreement between convergent eight-term Boltzmann and Monte Carlo calculations is found.

The aim of the present study was to evaluate the effect of natural deproteinized bone mineral on the temporal and spatial pattern of bone formation in a guided bone regeneration model system while using a bioresorbable membrane device. A periosteal skin flap was raised uncovering the calvaria of 20 rabbits. A stiff hemispherical dome made of polylactic acid was placed onto the roughened calvaria and anchored by screws. Prior to placement, the dome was either filled with peripheral blood (control group, 8 rabbits) or with blood and OsteoGraf/N-300 (test group, 12 rabbits). At 1 month, histologic sections revealed bone regeneration in both test and control domes to various degrees. In the test domes, bone height reached 78% (67-83) and bone volume was 11% (6-17), while in the control domes, bone height was 45% (14-67) and bone volume 6% (1-11). At 2 months, bone height was unchanged in the test group at 70% (67-83) and bone volume had only slightly increased to 16% (11-21). In the controls, height increased to 86% (60-100) and volume to 20% (9-27). Thus, in this model system, natural bone mineral fill contributed to accelerate initial bone neogenesis, while it did not contribute to increasing bone volume or bone height at later observation stages.

In generalization of former approaches for the simplified solution of the inhomogeneous electron Boltzmann equation a higher order solution technique has been developed. This technique is based on a multi-term expansion of the electron velocity distribution function and allows a strict study of the electron kinetics in plasmas acted upon by space-dependent electric fields. This solution technique is used to investigate the response of the plasma electrons to spatially limited disturbances of the electric field in weakly ionized plasmas of helium and mercury. By solving the kinetic equation with increasing order of the multi-term expansion the convergent solution of the kinetic problem and thus the strict spatial behaviour of the velocity distribution and of significant macroscopic properties of the electrons has been determined and analysed. Furthermore, the impact of higher order terms of the expansion has been revealed and the falsification of the velocity distribution and of related macroscopic properties has been evaluated when instead of the multi-term solution the simpler two-term solution of the kinetic equation is used.

Recently an improved technique to create a stable and homogeneous discharge for pumping excimer laser plasmas has been proposed in [1]. This technique is based on the additional use of a stabilizing low-current preliminary discharge. For the study of such laser discharges a self-consistent spatially homogeneous model with the inclusion of the time-dependent Boltzmann equation for the electrons, of the rate equation system arising from the heavy particle and photon kinetics and of the electrical circuit equations has been employed. A brief presentation of important features of the comprehensive model is given. An iterative procedure to solve self-consistently the system of kinetic, rate and circuit equations has been generalized and applied to discharge conditions where a dominant electron-electron interaction occurs. Model calculations have been performed for typical XeCl* laser plasmas which operate according to the improved discharge technique. On this basis a detailed analysis of main features of this laser discharge is given and the impact of various parameters on significant characteristics of the discharge is calculated and discussed.

Fraktographische Untersuchungen an Profilen der Legierung AlMgSi0,7 (AA6005A), geschweist mit dem Zusatzwerkstoff SG-AlMg5, haben gezeigt, das die in der Warmeeinfluszone vorhandenen Korngrenzenoffnungen das Bruchverhalten beeinflussen. Durch gezielt eingebrachte Ermudungszyklen ist es gelungen, den zeitlichen Ablauf des Risfortschritts auf der Bruchflache abzubilden. Korngrenzenoffnungen verhalten sich nicht wie scharfe Anrisse im Sinne der technischen Bruchmechanik. Erst nach einer unterschiedlich grosen Zahl von Lastwechseln konnen sich Ermudungsrisse an Korngrenzenoffnungen bilden. Ein nach Norm zulassiger Kantenversatz kann im Vergleich zu Korngrenzenoffnungen ein wirksamerer Risausloser sein. Influence of Grain Boundary Openings on Fracture Mechanisms in Welded AlMgSi Alloys In the present investigation AlMgSi0.7 extruded samples were welded with AlMg5 filler metal under conditions which favoured the formation of Grain Boundary Openings (GBO) in the heat affected zone. Fractographic examinations showed that GBO influence the fracture mechanisms. Applyingspecific fatigue block loadings the crack growth could be made visible on the fracture surface. It was demonstrated that a GBO does not behave like a sharp crack in the senseof classical fracture mechanics with immediate growth on application of stress. After a certain time of fatigue a crack is created at a GBO depending mainly on the stress amplitude. It is shown that a weld defect tolerated by standards can cause a more effective risk for fracture than the presence of the above mentioned GBO.

An efficient method for solving the inhomogeneous electron Boltzmann equation for a weakly ionized collision dominated plasma is represented. As a first application this method is used to investigate in a helium plasma the response of the electron velocity distribution function and of the relevant macroscopic quantities to the impact of spatially limited disturbances in the electric field. In addition to the field action elastic and (conservative) inelastic collisions of electrons with gas atoms are taken into account in the kinetic treatment. In this way the spatial relaxation behaviour of thc electrons and their establishment into homogeneous plasma states could be studied on a strict kinetic basis. Unexpectedly large relaxation lengths in electron acceleration direction have been found at medium electric fields.

The radial change of the electron velocity distribution function and of related macroscopic quantities of the electrons are studied theoretically and experimentally in the positive column plasma of a neon dc low pressure glow discharge. The theoretical investigations are based on the solution of electron kinetic equations. The measurements of electron kinetic quantities are performed by using a single probe technique with automated recording. To avoid the strict treatment of the complicated radially varying electron kinetics in the microphysical description of the column plasma, various simplifications of the appropriate inhomogeneous kinetic equation have been adopted in the past. Recently a strict solution approach of this complex kinetic problem could be developed. Using this strict solution approach and experimentally determined electron kinetic quantities the approximation quality, obtained by applying various simplified approaches to treat the electron kinetics as the conventional homogeneous approach, the nonlocal approach and the local field approximation, is illustrated and critically evaluated in this paper.

Severe loss of peri-implant supporting bone traditionally leads to the removal of the affected implant, but this may not be necessary in all cases. This paper presents a novel treatment approach aimed at the successful regeneration of bone lost to peri-implantitis using guided tissue regeneration (GTR). Four years after implant placement two patients presented with severe peri-implant tissue breakdown. Clinical signs of disease included bleeding on probing, suppuration, increased probeable pocket depth (4 to 9 mm) and a decreased level of clinical attachment (2 to 10 mm). Radiographic analysis revealed 2.6 to 7.1 mm loss of supporting bone. Treatment of these lesions included raising flaps, wound debridement, and rinsing with sterile saline and 0.2% chlorhexidine digluconate. Subsequently, ePTFE membranes were adapted around the necks of the implants and the flaps sutured around the necks of the implants, allowing for transmucosal healing. Both patients were placed on a 10-day antibiotic regimen and instructed to rinse twice daily with a 0.12% chlorhexidine solution. They were reevaluated every 3 weeks at which time professional plaque control was performed. After 4 1/2 and 6 1/2 months, respectively, the membranes required removal due to infection. The radiographic analysis 1 year after membrane removal revealed 1.5 to 3.6 mm of bone gain. As a result of regenerative therapy the implants in both these patients were successfully maintained. It can be concluded that implants with severe loss of bone resulting from peri-implantitis need not always be extracted. A potential approach for the treatment of peri-implant bone destruction is GTR therapy using strict attention to good antimicrobial therapy.

A relaxation study of an electron group in collision dominated weakly ionized plasmas has been performed. The study is based on the two-term approximation of the Legendre polynomial expansion of the electron velocity distribution in the nonstationary Boltzmann equation. To overcome the limitation of the conventional quasi-stationary treatment of the distribution anisotropy, a very efficient solution approach of the nonstationary kinetic equation in two-term approximation has been developed which allows for a strict nonstationary treatment of the distribution anisotropy. By using this approach the temporal evolution of the isotropic and anisotropic distribution of the electrons has been investigated for a model plasma, which involves typical features of an inert gas plasma. A comparison of the results with corresponding ones obtained by applying the conventional approach under various parameter conditions clearly indicates a pronounced falsification of the real relaxation course by the latter approach.

Objective, reliable, and valid diagnostic criteria are required for studies of HIV-associated periodontal conditions. A set of diagnostic criteria were devised based on a literature review and the clinical experience of the authors. Validity was assessed by comparison with clinical photographs and the criteria were evaluated and refined for ease of use and objectivity. To assess the reliability of the criteria, 9 experienced examiners were shown 20 clinical photographs accompanied by brief vignettes of clinical information. Each examiner was asked to identify signs evident in a particular area of the photograph and to record a diagnosis. Five examiners were then trained and calibrated in the use of the criteria. Finally, all 9 examiners were shown the original 20 photographs and asked to identify signs and record diagnoses. The examiners showed only fair reliability in the recognition of clinical signs, made diagnoses intuitively, and had only fair agreement on the diagnosis of periodontal diseases. The inter-examiner reliability of examiners trained and calibrated in the use of the criteria increased and was greater than among untrained examiners. Rigid diagnostic criteria are essential in epidemiologic studies. Inter-examiner reliability will be increased if examiners are trained in their use and calibrated in the recognition of clinical signs. Diagnostic criteria should be modified as understanding of the diseases they classify increases. The proposed criteria will enhance the value of studies of HIV-associated periodontal changes and will contribute to that understanding.

During childhood, many people acquire primary infection with cytomegalovirus (CMV), one of the herpes viruses. If they later become immunosuppressed, such as occurs with human immunodeficiency virus (HIV) infection, CMV is likely to become reactivated. Severe disease caused by CMV is life-threatening in the HIV-infected population. CMV retinitis, gastritis, colitis, pneumonia, encephalitis and hepatitis have all been reported, but oral lesions due to infection with CMV are rarely reported. We report a case of oral CMV infection which at first was clinically indistinguishable from HIV-associated periodontal disease.

Natural photosynthesis uses sunlight to drive the conversion of energy-poor molecules (H2O, CO2) to energy-rich ones (O2, (CH2O)n). Scientists are working hard to develop efficient artificial photosynthetic systems toward the “Holy Grail” of solar-driven water splitting. High on the list of challenges is the discovery of molecules that efficiently catalyze the reduction of protons to H2. In this Account, we report on one promising class of molecules: cobalt complexes with diglyoxime ligands (cobaloximes). Chemical, electrochemical, and photochemical methods all have been utilized to explore proton reduction catalysis by cobaloxime complexes. Reduction of a CoII-diglyoxime generates a CoI species that reacts with a proton source to produce a CoIII-hydride. Then, in a homolytic pathway, two CoIII-hydrides react in a bimolecular step to eliminate H2. Alternatively, in a heterolytic pathway, protonation of the CoIII-hydride produces H2 and CoIII. A thermodynamic analysis of H2 evolution pathways sheds new lig...

The impact of a secondary electron beam, generated at the electrodes and accelerated in the sheaths, on the self-consistent treatment of the electron behaviour in an rf bulk plasma has been investigated by a parametric study. Source of electrons in the plasma are collisional ionization and secondary electron injection. Electrons are lost by ambipolar diffusion to the electrodes of a parallel plate rf discharge configuration. The non-stationary Boltzmann equation is used to determine self-consistently the rf field amplitude necessary for maintaining the steady-state rf bulk plasma as well as the time resolved behaviour of the electron energy distribution function and of all contributions to the electron particle and power balance, at given source rate and energy distribution of secondary electron injection.