Influence of Microbiological Activity on the Mobility of Redoxsensitive Radionuclides in Sediments

The influence of microbial activity on the transport and migration behaviour of redox-sensitive radionuclides (e.g. Technetium (Tc) and Selenium (Se)) in groundwater environment were investigated within an interdisciplinarary research program. Soil material and sediments were investigated with batch- and recircu-lation column experiments. The number of microorganisms in the water was determined by counting the colony forming units (CFU) on R2A agar at regular periods.

The results of sterile and non sterile recirculation column experiments showed within 80 days a high fixation of the radionuclides in the unsterile samples (80% of Tc, 50% of Se compared with the initial concentration Ao), and no fixation in the sterile samples. There was no difference in the redox values.

It could be shown that the immobilisation of the redox-sensitive elements Tc and Se are strongly determined by microbial activity, depending on the different sediments and their microbial live stock. There are indications that the microorganisms found in the non sterile columns are allochthonous bacteria which were dragged into the experimental systems and samples during laboratory work and sampling. The composition of the microbial flora was shown to be very heterogenous and different in each individual column and within the same column at different times. Thus these columns might have been contaminated with microorganisms during sampling and handling of the experimental systems under non sterile conditions, as done generally in most laboratories.

Entropy of the hard-core model

The entropy of the hard-core model is analyzed subject to dimension, system size and particle density. Inspired by the exactly solvable one-dimensional case and the results from a virial expansion, we suggest a scaling relation for the two-dimensional and three-dimensional case. These relations are compared with numerical results, obtained by a modified Widom's particle insertion method. The notion of finite size effects, relevant for atomic glass-forming systems, is discussed in the context of the present results.

Density-dependent reorientation and rehybridization of chemisorbed conjugated molecules for controlling interface electronic structure

The adsorption of the molecular acceptor hexaazatriphenylene-hexacarbonitrile on Ag(111) was investigated as function of layer density. We find that the orientation of the first molecular layer changes from a face-on to an edge-on conformation depending on layer density, facilitated through specific interactions of the peripheral molecular cyano groups with the metal. This is accompanied by a rehybridization of molecular and metal electronic states, which significantly modifies the interface and surface electronic properties, as rationalized by theoretical modeling.

Reaction of molecular and atomic deuterium with methanol on Pd(111)

Multiplexed thermal desorption spectroscopy was used to study the influence of preadsorbed and postadsorbed deuterium on a methanol monolayer on Pd(111). In particular, the effect of atomic deuterium exposure on the reaction products was examined in detail. Preadsorbed deuterium hinders the formation of chemisorbed methanol and favors physisorption of methanol. This leads to a strong reduction of methanol dehydrogenation during sample heating. Postadsorption of molecular deuterium also changes partially chemisorbed to physisorbed methanol. No deuteration of methanol is found under these conditions. With atomic deuterium exposure, however, significant amounts of deuterated methanol, from methanol-D1 through methanol-D4, can be produced. In addition, D exposure also causes an increased dehydrogenation probability during sample heating. The probabilities for methanol deuteration, for methanol dehydrogenation, and for D-atom bulk absorption have been determined quantitatively.

Methanol adsorption on Cu(110) and the angular distribution of the reaction products

Integral and angle resolved thermal desorption spectroscopies were used to study methanol adsorption and oxidation on clean and oxygen covered Cu(110) surfaces. Special emphasis was put on the Cu-CuO stripe phase, which forms when the Cu(110) surface is covered with 0.25 ML of oxygen. In the temperature regime between 200 and 300 K associative desorption of methanol and water takes place, showing a normal desorption character with peaks shifting to lower temperature with increasing coverage and with a nearly cosine angular desorption distribution. In the temperature range of about 350 K formaldehyde, hydrogen, and again methanol desorb nearly concomitantly in the form of a very narrow peak (full width at half maximum=10 K), with peaks shifting to higher temperature with increasing methanol coverage. The angular distribution of these peaks is strongly forward focused, indicating activation barriers being involved. In the case of the Cu-CuO stripe phase the angular distribution of the desorption products is clearly different in the [110] and [001] azimuthal directions, demonstrating the influence of the border lines between the copper and the copper oxide stripes on the desorption process.

Model reaction studies on vanadium oxide nanostructures on Pd(111)

Deuterium desorption and reaction between deuterium and oxygen to water has been studied on ultrathin vanadium oxide structures prepared on Pd(111). The palladium sample was part of a permeation source, thus enabling the supply of atomic deuterium to the sample surface via the bulk. Different vanadium oxide films have been prepared by e-beam evaporation in UHV under oxygen atmosphere. The structure of these films was determined using low energy electron diffraction and scanning tunneling microscopy. The mean translational energy of the desorption and reaction products has been measured with a time-of-flight spectrometer. The most stable phases for monolayer and submonolayer VOx are particular surface-V2O3 and VO phases at 523 and 700 K, respectively. Thicker films grow in the form of bulk V2O3. The mean translational energy of the desorbing deuterium species corresponds in all cases to the thermalized value. Apparent deviations from this energy distribution could be attributed to different adsorption/desorption and/or accommodation behaviors of molecular deuterium from the gas phase on the individual vanadium oxide films. The water reaction product shows a slightly hyperthermal mean translational energy, suggesting that higher energetic permeating deuterium contributes with higher probability to the water formation.

Manipulating the activation barrier for H2(D2) desorption from potassium-modified palladium surfaces

In this work the permeation and desorption of hydrogen (deuterium) from potassium-modified Pd(111) and polycrystalline palladium surfaces have been studied in the temperature range from 350 to 523 K. Time-of-flight spectroscopy has been used to determine the translational energy distributions of associatively desorbing H(2)(D(2)) molecules as a function of the potassium coverage and additional isotropic O(2) and CO background pressures. It turned out that the energy distribution of the hydrogen desorption flux is thermalized for the clean Pd surfaces but hyperthermal for the potassium-covered surfaces. The activation barrier for adsorption was found to increase with the potassium coverage but to decrease again in the presence of coadsorbates such as O(2) or CO. Especially by choosing different isotropic CO pressures, the effective desorption barrier for hydrogen could be reversibly decreased and increased, which resulted in the equivalent changes of the mean kinetic energies of the desorbing H(2) molecules.

Reduction of high dislocation of the hip using a distraction nail before arthroplasty

We report the case of a 22-year-old woman who underwent plate and screw fixation for a traumatic left acetabular fracture and fixation with cancellous screws for an associated femoral neck fracture. Two months later, the internal fixation became infected and was removed. This resulted in a painful high dislocation of the hip. We solved the problem with continuous soft-tissue distraction using a fully implantable motorised distraction nail in order to reduce the proximal femur prior to total hip arthroplasty. To our knowledge, this is the first time that reduction of a high dislocation of the hip has been performed using such a system.

Growth kinetics, structure, and morphology of para-quaterphenyl thin films on gold(111)

The adsorption, desorption, and growth kinetics as well as the thin film morphology and crystal structure of p-quaterphenyl (4P) grown under ultrahigh vacuum conditions on single crystalline Au(111) have been investigated. Thermal desorption spectroscopy (TDS) reveals two distinct first-order peaks attributed to monolayer desorption followed by a zero-order multilayer desorption. The saturation coverage of the full 4P monolayer has been quantitatively measured with a quartz microbalance to be 8 x 10(13) molecules/cm2. Using low energy electron diffraction the structures of the 0.5 and 1 ML (monolayer) adsorbates have been studied, showing highly regular arrangements of the 4P molecules, which are affected by the (111) surface structure. At the transition from 0.5 to 1 ML a structural compression of the overlayer has been observed. The behavior of thicker 4P films has been investigated by combined TDS-XPS (XPS-x-ray photoelectron spectroscopy). A temperature-induced recrystallization process at about 270 K has been observed for a 7 nm thick 4P film grown at 93 K, corresponding to a transition from a disordered layerlike growth to a crystalline island growth. Ex situ optical microscopy and atomic-force microscopy investigations have revealed needle-shaped 4P islands. Applying x-ray diffraction the crystalline order and epitaxial relationship of the 4P films with 30 nm and 200 nm mean thicknesses have been determined.

Water formation on Pd(111) by reaction of oxygen with atomic and molecular hydrogen

In this work we have studied the steady-state reaction of molecular and atomic hydrogen with oxygen on a Pd(111) surface at a low total pressure (<10(-7) mbar) and at sample temperatures ranging from 100 to 1100 K. Characteristic features of the water formation rate Phi(pH2; pO2; TPd) are presented and discussed, including effects that are due to the use of gas-phase atomic hydrogen for exposure. Optimum impingement ratios (OIR) for hydrogen and oxygen for water formation and their dependence on the sample temperature have been determined. The occurring shift in the OIR could be ascribed to the temperature dependence of the sticking coefficients for hydrogen (SH2) and oxygen (SO2) on Pd(111). Using gas-phase atomic hydrogen for water formation leads to an increase of the OIR, suggesting that hydrogen abstraction via hot-atom reactions competes with H2O formation. The velocity distributions of the desorbing water molecules formed on the Pd(111) surface have been measured by time-of-flight spectroscopy under various conditions, using either gas-phase H atoms or molecular H2 as reactants. In all cases, the desorbing water flux could be represented by a Maxwellian distribution corresponding to the surface temperature, thus giving direct evidence for a Langmuir-Hinshelwood mechanism for water formation on Pd(111).

Gastroscope processing in washer-disinfectors at three different temperatures

Endoscopes are processed chemo-thermally at approximately 56 degrees C in washer-disinfectors in Germany. In this study we investigated the processing of gastroscopes by an endoscope washer-disinfector at different temperatures. A total of 87 gastroscopes were tested hygienically and microbiologically before manual cleaning (after patient use), as well as after manual cleaning and after endoscope washer-disinfector processing at running temperatures of 43, 51 and 56 degrees C. In all tests the suction/biopsy channels of the gastroscopes were flushed with 50 mL sterile solution throughout their full length, from the proximal to the distal ends. The rinse solutions were plated on to various culture media. Also, in order to detect low bacterial counts, 3x10 mL rinse solution was membrane filtrated. The German guideline level for total bacterial counts, applicable since 2002, was exceeded at all temperatures tested (159 cfu/mL at 43 degrees C, <60 cfu/mL at 51 degrees C, and 8 cfu/mL at 56 degrees C). A temperature increase from 43 to 51 degrees C resulted in a highly significant reduction of the residual contamination by aerobic bacteria (P<0.001, Mann-Whitney U Test), Gram-negative bacilli (P<0.001), and pseudomonads (P=0.002). A further temperature increase from 51 to 56 degrees C resulted in a further highly significant drop in residual contamination by aerobic bacteria (P=0.021) and pseudomonads (P=0.036). The aim of the user-minimizing material damage to endoscopes or prolonging their product life-cannot be achieved through lowering the processing temperature without putting patients at risk. In order to ensure adequate processing, endoscope washer-disinfectors should meet the requirements of current draft standards.

Schistocytic anaemia, severe thrombocytopenia, and renal dysfunction: thrombotic microangiopathy due to severe acquired ADAMTS-13 deficiency. Case 2

We present the case of a woman (age: 64 years) with acute thrombotic microangiopathy due to severe acquired ADAMTS-13 (von Willebrand factor-cleaving protease) deficiency. She was successfully treated with plasma exchange therapy and glucocorticosteroids. She relapsed seven months later, and splenectomy led to lasting remission. Pathomechanisms of thrombotic thrombocytopenic purpura, especially the role of ADAMTS-13, are discussed and therapeutic measures outlined.

When scanning tunneling microscopy gets the wrong adsorption site: H on Rh(100)

At low tunneling resistance, scanning tunneling microscopy (STM) images of a Rh(100) surface with adsorbed hydrogen reproducibly show protrusions in all bridge sites of the surface, leading to a naive interpretation of all bridge sites being occupied with H atoms. Using quantitative low-energy electron diffraction and temperature programmed desorption we find a much lower H coverage, with most H atoms in fourfold hollow sites. Density functional theory calculations show that the STM result is due to the influence of the tip, attracting the mobile H atoms into bridge sites. This demonstrates that STM images of highly mobile adsorbates can be strongly misleading and underlines the importance of additional analysis techniques.

Effects of kinins on mammalian spermatozoa and the impact of peptidolytic enzymes

Effects of kinins, mainly bradykinin (Bk), and other components of the kallikrein-kinin system on sperm motility and further fertility-related functions have been described repeatedly. However, reported data are in part controversial and the mechanism of kinin effects on sperm motility is not yet understood. In the present report we describe a significant promoting effect of Bk on sperm motility at subnanomolar concentrations. This effect was stabilized and even increased by suppression of Bk hydrolysis in semen samples. As sperm membrane-bound angiotensin-converting enzyme and neutral metalloendopeptidase are mainly involved in Bk hydrolysis, an effective cocktail of enzyme inhibitors promoting the sperm motility consists of phosphoramidon and lisinopril (both at 10-7 m). The effects of Bk on sperm cells are not mediated by the B2 Bk receptor. Using several biochemical, molecular and genetic methods we could not detect any Bk receptor on spermatozoa.

Molecular and functional imaging technology for the development of efficient treatment strategies for gliomas

Gliomas are the most common types of brain tumors, which invariably lead to death over months or years. Before new and potentially more effective treatment strategies, such as gene therapy, can be effectively introduced into clinical application the following goals must be reached: (1) the determination of localization, extent and metabolic activity of the glioma; (2) the assessment of functional changes within the surrounding brain tissue; (3) the identification of genetic changes on the molecular level leading to disease; and in addition (4) a detailed non-invasive analysis of both endogenous and exogenous gene expression in animal models and in the clinical setting. Non-invasive imaging of endogenous gene expression by means of positron emission tomography (PET) may reveal insight into the molecular basis of pathogenesis and metabolic activity of the glioma and the extent of treatment response. When exogenous genes are introduced to serve for a therapeutic function, PET imaging techniques may reveal the assessment of the location, magnitude and duration of therapeutic gene expression and its relation to the therapeutic effect. Here, we review the main principles of PET imaging and its key roles in neurooncology research.

Comparative permeation studies for delta-aminolevulinic acid and its n-butylester through stratum corneum and artificial skin constructs

The improvement of the permeation properties through excised human stratum corneum and artificial skin constructs (ASC) of delta-aminolevulinic-n-butylester (ABE) compared with delta-aminolevulinic acid (ALA) was investigated. For this purpose the permeated amounts of each substance were determined depending on time in a Franz diffusion cell experiment with stratum corneum and ASC, respectively. Furthermore the barrier properties of ASC were compared with those of stratum corneum. Detection of both substances was performed by high-performance liquid chromatography (HPLC) analysis. For the determination of ABE a new HPLC method was developed. ABE could be determined with the new HPLC method with sufficient sensitivity (detection limit: 0.1 microg/ml) after derivatisation with o-phthalaldehyde (OPA). Stratum corneum and ASC were more permeable for ABE than for ALA. The permeation coefficient P of ABE through stratum corneum was nearly ten-fold higher than that of ALA. Using ASC as permeation barrier the permeation coefficient of ABE was about 22-fold higher than that of ALA. ABE and ALA permeated 142-fold and 64-fold, respectively, faster through ASC than through stratum corneum.

Insomnia related to dysthymia: polysomnographic and psychometric comparison with normal controls and acute therapeutic trials with trazodone

Utilizing polysomnography (PSG) and psychometry, objective and subjective sleep and awakening quality was investigated in 11 patients (mean age 50 +/- 14) with nonorganic insomnia (F 51.0) related to dysthymia (F 34.1) as compared with 11 age- and sex-matched normal controls. Patients demonstrated decreased sleep efficiency and sleep stage S2 as well as increased sleep latency to S1, S2 and S3, wakefulness within the total sleep period, number of awakenings, S1 and REM sleep. There was no intergroup difference in REM latency. Subjective sleep quality and the total score of the Self-Assessment Scale for Sleep and Awakening Quality (SSA) were deteriorated as were evening and morning well-being, mood, affectivity and drowsiness. Noopsychic measures showed deteriorated numerical memory, fine motor activity and reaction time variability. In a placebo-controlled crossover design study, the acute effects of 100 mg trazodone, a serotonin reuptake inhibitor with a sedative action due to 5HT(2) and alpha(1) receptor blockade, were investigated in the patients. As compared with placebo, trazodone induced an increase in slow-wave sleep (S3 + 4), a lengthening of REM latency, a decrease in REM sleep and a normalization of the periodic leg movement (PLM) index. In the morning, there was a minimal increase in somatic complaints and a decrease in critical flicker frequency and systolic blood pressure. In conclusion, our study demonstrated that dysthymia induced significant changes in objective and subjective sleep and awakening quality, which were counteracted by 100 mg trazodone, thus suggesting a key-lock principle in the treatment of nonorganic insomnia related to dysthymia with this drug.

Growth of a vanadium oxide layer on V(100) and its reactivity towards atomic hydrogen

The influence of a surface oxide on V(100) on the sticking of atomic hydrogen was studied. The oxide was produced by dosing with oxygen at different surface temperatures and characterized by AES and XPS. Thermal desorption spectroscopy was used to determine the sticking coefficient of atomic hydrogen. The kinetics of oxidation and the stability of the formed oxide have been studied in detail. The highest oxidation rate was obtained at a surface temperature of 473 K, producing a V2O3 over-layer. Although the sticking coefficient for atomic hydrogen decreases from 0.14 on the oxide free V(100) surface to 0.015 on the V2O3 surface, the sticking coefficient for atomic hydrogen was still several orders of magnitude higher than that for molecular hydrogen. This is relevant in respect of the use of the hydrogen-vanadium system for energy storage.