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Summary: Background: The extent of arterial disease in patients with erectile dysfunction (ED) non-responsive to intracavernosal injection of Alprostadil is of importance for therapeutic options. However, published evidence, in particular angiographically validated is scarce. Here we investigated arterial lesion patterns in this specific patient cohort by selective angiography. Patients and methods: A cohort of 239 patients received a clinical and duplex-sonographic workup for ED of suspected vascular origin. Duplex ultrasound of the cavernosal arteries was performed after intracavernosal injection of 10 μg Alprostadil. Consequently, standardized workup included grading of the erectile and determination of peak systolic velocity (PSV) and end-diastolic velocity (EDV) in both cavernosal arteries. PSV-values below 30 cm/sec indicated reduced arterial flow, whereas EDV-values above 15 cm/sec indicated a venous leak of the pudendal veins. All patients with suspected arterial ED based on duplex sonography underwent contrast-enhanced computed tomography. Endovascular therapy was carried out in ED patients not responsive or with significant side effects to PDE-5-inhibitors or Alprostadil by selective angiographic depiction of erection-related arteries. Results: 54 patients with a mean age of 61.2 (±9.8) years underwent angioplasty of erectionr elated arteries. Out of these 48/54 (89%) patients presented with an erection considered insufficient for penetration (E0-E3) subsequent to intracavernous application of 10 μg Alprostadil. 14/48 (29%) patients had bilateral arterial obstructions and 34/48 (71%) had unilateral disease. Commonly affected was the internal pudendal artery (n = 31, 65%), followed closely by the common penile artery (n = 30, 64%). The least affected arteries were the dorsal penile (n = 6, 13%), hypogastric (n = 4, 8%), common iliac (n = 4, 8%), cavernosal (n = 4, 8%), and inferior gluteal (n = 1, 2%) arteries. Conclusions: Arterial obstructions amenable to endovascular revascularization are frequent in patients non-responsive to intracavernosal prostaglandin administration. Therapeutic strategies in ED patients non-responsive to conservative measures should therefore consider endovascular treatment opportunities.

Purpose Bacillus Calmette-Guérin (BCG)-treatment is an established treatment for bladder cancer, but its mechanisms of action are not fully understood. High-risk non-muscle invasive bladder-cancer (NMIBC)-patients failing to respond to BCG-treatment have worse prognosis than those undergoing immediate radical cystectomy and identification of patients at risk for BCG-failure is of high priority. Several studies indicate a role for nitric oxide (NO) in the cytotoxic effect that BCG exerts on bladder cancer cells. In this study we investigated whether NO-synthase (NOS)-gene polymorphisms, NOS2-promoter microsatellite (CCTTT)n, and the NOS3-polymorphisms-786T>C (rs2070744) and Glu298Asp (rs1799983), can serve as possible molecular markers for outcome after BCG-treatment for NMIBC. Materials and methods All NMIBC-patients from a well-characterized population based cohort were analyzed (n=88). Polymorphism data were combined with information from 15-years of clinical follow-up. The effect of BCG-treatment on cancer-specific death (CSD), recurrence and progression in patients with varying NOS-genotypes were studied using Cox proportional hazard-models and log rank tests. Results BCG-treatment resulted in significantly better survival in patients without (Log rank: p=0.006; HR: 0.12, p=0.048), but not in patients with a long version ((CCTTT)n ≧13 repeats) of the NOS2-promoter microsatellite. The NOS3-rs2070744(TT) and rs1799983(GG)-genotypes showed decreased risk for CSD (Log rank(TT): p=0.001; Log rank(GG): p=0.010, HR(GG): 0.16, p=0.030) and progression (Log rank(TT): p, Graphical abstract, Highlights • 30% of BCG treated bladder cancer (NMIBC)-patients do not respond to BCG-treatment. • We need to identify BCG failures before the BCG-treatment is given. • Altered NOS2 and NOS3 gene activity may be associated with BCG treatment outcome. • NOS-polymorphisms are possible BCG-failure biomarkers in bladder cancer patients.

Geochemical data are presented for the kimberlitic Holocene Igwisi Hills volcanoes (IHV), Tanzania, which preserve extra-crater lavas and pyroclastic rocks. Their young age and exceptional preservation enable investigation of kimberlite magma compositions and alteration pathways of kimberlites. The IHV lavas have a variable matrix assemblage dominated by calcite, olivine and a serpentine-like mineral (termed serpentine-X). Minor primary groundmass phases include apatite, phlogopite, monticellite, perovskite and spinel representing late-stage crystalisation. Secondary phases include hydrogarnet, a mixed-layer chlorite–vermiculite–montmorrilonite, minor brucite and low-temperature oxides and clays such as goethite and jamborite. The matrix of pyroclastic rocks is dominated by calcite with fewer groundmass phases. The parental magmas are inferred to have had ~ 21 wt.% SiO2, ~ 22 wt.% CaO, ~ 23 wt.% MgO and Mg# ~ 70. The IHV are classified as calcite kimberlites. The total volatile concentrations of the primary melt are ~ 14 wt.%, which predominantly consists of CO2 although the H2O content is also high. Whole-rock geochemical analyses indicate minor crustal contamination, low-temperature alteration and weathering. Pervasive serpentinisation in both lavas and pyroclastic rocks results from low-temperature alteration induced by the circulation of meteoric waters during cooling. Serpentine-X is potentially a new mineral and is richer in Al2O3 and FeO and poorer in SiO2 than published analyses of serpentine minerals. These compositions are attributed to a 1:2 mixture of serpentine and hydrotalcite. We propose that serpentine-X has replaced a reactive, late stage residual silicate glass, the existence of which helps explain the presence of vesicular scoria (similar to glassy basaltic pyroclasts) and viscous kimberlite lavas.

Objective: To analyze different polyunsaturated fatty acid (PUPA) tissue levels in malignant compared with benign prostatic tissue from the same prostate specimens. Materials and methods: Fresh frozen benign and malignant prostatic tissue was obtained from radical prostatectomy specimens in 49 men with pathologic stage pT2a prostate cancer. Histopathologic examination confirmed that all tissues from each prostate being analyzed were either completely benign or almost totally malignant. The PUFA composition in these tissues was determined by gas-liquid chromatography on a capillary column. The relative amount of each PUFA (% of total fatty acids) was quantified by integrating the area under the peak and dividing the result by the total area of all fatty acids. Results: Tissue levels of dihomo-gamma-linolenic acid, (C20:3w6), an omega-6 PUFA and a major precursor of omega-6 PUFA metabolites, were significantly higher in malignant compared with benign tissues (P = 0.002). Tissue levels of the downstream omega-6 metabolites, arachidonic acid (AA) (20:4 omega 6), and adrenic acid, (22:4 omega 6), were significantly lower in cancer tissues, (P < 0.0001 and P = 0.013, respectively). Overall, the total levels of omega-6 PUPA were lower in cancer (P = 0.001). Conclusion: We found that the omega-6 PUPA AA and adrenic acid are decreased in malignant prostatic tissues compared with benign tissues from the same prostates. These findings provide additional evidence that dietary fat is associated with prostatic carcinogenesis.

A new classification and nomenclature scheme for the amphibole-supergroup minerals is described, based on the general formula AB 2 C 5 T 8 O 22 W 2 , where A = □, Na, K, Ca, Pb, Li; B = Na, Ca, Mn 2+ , Fe 2+ , Mg, Li; C = Mg, Fe 2+ , Mn 2+ , Al, Fe 3+ , Mn 3+ , Ti 4+ , Li; T = Si, Al, Ti 4+ , Be; W = (OH), F, Cl, O 2− . Distinct arrangements of formal charges at the sites (or groups of sites) in the amphibole structure warrant distinct root names , and are, by implication, distinct species; for a specific root name, different homovalent cations (e.g., Mg vs. Fe 2+ ) or anions (e.g., OH vs. F) are indicated by prefixes (e.g., ferro-, fluoro-). The classification is based on the A, B, and C groups of cations and the W group of anions, as these groups show the maximum compositional variability in the amphibole structure. The amphibole supergroup is divided into two groups according to the dominant W species: W (OH,F,Cl)-dominant amphiboles and W O-dominant amphiboles (oxo-amphiboles). Amphiboles with (OH, F, Cl) dominant at W are divided into eight subgroups according to the dominant charge-arrangements and type of B-group cations: magnesium-iron-manganese amphiboles, calcium amphiboles, sodium-calcium amphiboles, sodium amphiboles, lithium amphiboles, sodium-(magnesium-iron-manganese) amphiboles, lithium-(magnesium-iron-manganese) amphiboles and lithium-calcium amphiboles. Within each of these subgroups, the A- and C-group cations are used to assign specific names to specific compositional ranges and root compositions. Root names are assigned to distinct arrangements of formal charges at the sites, and prefixes are assigned to describe homovalent variation in the dominant ion of the root composition. For amphiboles with O dominant at W, distinct root-compositions are currently known for four (calcium and sodium) amphiboles, and homovalent variation in the dominant cation is handled as for the W (OH,F,Cl)-dominant amphiboles. With this classification, we attempt to recognize the concerns of each constituent community interested in amphiboles and incorporate these into this classification scheme. Where such concerns conflict, we have attempted to act in accord with the more important concerns of each community.

We report on the electronic properties of n-doped (n ∼ 1018 cm-3) ZnSe/GaAs(001) heterostructures grown by molecular beam epitaxy with pre-deposition of different amounts of Zn or Se in the fractional monolayer range at ZnSe epilayer growth start. Special attention is spent on the depletion layers on both sides of the interface and to the conduction band potential barrier. The depletion layers are studied by Raman spectroscopy and electrochemical capacitance-voltage profiling, while the potential barrier height is derived from temperature-dependent transport across the hetero-interface. We observe a carrier-depleted interface region with an overall thickness of about 50 to 65 nm. For a Zn-rich growth start the thickness contribution on the GaAs-side slightly prevails, but for Se-pre-deposition, the ZnSe-side contribution clearly dominates, and for the highest Se pre-deposition the total depletion width is slightly reduced. The potential barrier is 550 meV for the Zn-rich hetero-interface. With Se pre-deposition it decreases down to about 70 meV, which implies an increase of the conductivity across the hetero-interface by as much as five orders of magnitude. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Eukaryotic cell surface proteins are often modified by a glycosylphosphatidylinositol (GPI) anchor. More than 200 of these post-translationally altered proteins are presently known, a prominent example being the prion protein (PrP). Although the significance of the GPI anchor is well recognized, efforts to study its function are hampered due to its complex chemical nature, which combines hydrophilic glycosyl chains with hydrophobic lipid moieties. Here we describe a general method for the synthesis of a GPI-anchored peptide containing an N-terminal Cys. This module can be employed for the production of proteins containing a natural GPI anchor using expressed protein ligation.

We show that important layer parameters of the double barrier active region in semimagnetic II–VI semiconductor resonant tunneling diodes (RTDs) can be accurately determined from high-resolution X-ray diffraction (HR-XRD) scans of complete structures. This is remarkable, since the scattering volume of the typically only few nm thin double barrier region is low compared to the thick, complex contact and buffer layers it is embedded in. The parameters obtained by HR-XRD of several RTD structures are correlated with current–voltage characteristics, finding good agreement with the expected exponential dependence of the off-resonance tunneling current on the measured barrier thickness and height. Thus direct and nondestructive determination and optimization of the active region properties are possible for such II–VI spintronic devices.

Metamorphic assemblages within Karoo basalt xenoliths, found within volcaniclastic kimberlite of the B/K9 pipe, Damtshaa, Botswana, constrain conditions of kimberlite alteration. Bultfonteinite and chlorite partially replace the original augite-plagioclase assemblage, driven by the serpentinisation of the kimberlite creating strong chemical potential gradients for Si and Mg. Hydrogarnet and serpentine replace these earlier metamorphic assemblages as the deposits cool. The bultfonteinite (ideally Ca2SiO2[OH,F]4) and hydrogarnet assemblages require a water-rich fluid containing F−, and imply hydrothermal alteration dominated by external fluids rather than autometamorphism from deuteric fluids. Bultfonteinite and hydrogarnet are estimated to form at temperatures of ca. 350–250°C, which are similar to those for serpentinisation. Alteration within the B/K9 kimberlite predominantly occurs between 250 and 400°C. We attribute these conditions to increased efficiency of mass transfer and chemical reactions below the critical point of water and a consequence of volume-increasing serpentinisation and metasomatic reactions that take place over this temperature range. A comparison of the B/K9 kimberlite with kimberlites from Venetia, South Africa suggests that the composition and mineralogy of included xenoliths affects the alteration assemblages within kimberlite deposits.

The compositions of kimberlite magma and associated melts during eruption and hypabyssal intrusion are elusive due to contamination by xenolithic material and strong alteration, notably by serpentinisation. Textures and mineralogical attributes of kimberlite dykes and sills indicate that some groundmass minerals, including igneous calcite, are replaced in the process of serpentinisation. Large volume changes during serpentinisation occur in chemically open systems, producing an increase in SiO2 and MgO and decrease in CaO and CO2 in bulk rock chemistry. Reconstructed compositions of kimberlite melt components, taking into account alteration, are shifted towards compositions transitional to carbonatite, indicating overestimation of SiO2 and MgO contents in previous published estimates of kimberlite melt compositions. Further evidence that these compositions are problematic come from experimental investigations of three putative kimberlite melt compositions. Experiments at 100 and 200 MPa at temperatures of 1100 °C to 1275 °C with excess CO2, H2O and CO2–H2O mixtures show that previously proposed compositions cannot be pure melts under eruptive conditions. Their SiO2 and MgO-rich characteristics lead to high liquidus temperatures (> 1350 °C) inconsistent with estimated kimberlite magma temperatures (

Organic dyes are routinely used in labeling assays and sensing of biological molecules. Semiconductor quantum dots (QDs) have attractive features, particularly good resistance to photobleaching and narrow emission bands, which make them potential replacements for organic dyes. Using a previously identified synthetic peptide, a QD, and the R-phycoerythrin (RPE) dye, we have examined various labeling strategies for detecting Bacillus anthracis spores. The RPE dye performed well, but we were unable to demonstrate successful binding of the QD by flow cytometry or confocal microscopy. Using a related conjugation strategy, Jurkat T-cells were labeled via a monoclonal antibody (mAb) that binds to the CXC chemokine receptor, CXCR4. It was noted that both QD and RPE labeled the cells. Based on electron microscopy data, we propose that a dense network of fibers on the Bacillus anthracis spore surface prevented the QD, but not RPE, from binding. These results suggest that the nature of the biological surface must be considered when using QDs as replacements for organic dyes in biological sensing.

This study focuses on an aqueous one-pot method for synthesis of CdSe/ZnS core/shell QDs using microwave radiation. The novelty of the study is the use of Zn(NH3)4 2+ as the zinc source. Using an initial solution with the composition Cd1Se1Zn6MPA20, the QDs obtained upon heating at 160 °C for 60 min were not high quality, as evidenced by a quantum yield of 1.5%, due to the poor interface between the core and shell. Postsynthesis UV irradiation of the as-prepared QDs for 30 min could be used to improve the quantum yield to 22%, but the technique is not practical for large-scale applications. By increasing the amount of Cd 2+ in the initial solution to Cd4Se1Zn4MPA20, we formed CdSe/CdS/ZnS QDs after heating at 150 °C for 90 min, which contained less interfacial trap-states and as a result, had a higher quantum yield of 13%. These QDs were characterized by powder diffraction, electron microscopy, and X-ray photoelectron spectroscopy. Uptake of the microwave-optimized QDs by alveolar macrophages was compared in a side-by-side study against commercial QDs, QDot585. Despite having a lower relative quantum yield (13%) as compared to the commercial QDs (65%), the microwave-synthesized QDs at 20 nM concentrations were readily detected within the macrophages after 20 min of incubation.

The geothermobarometric potential of tourmaline has been assessed by investigating element exchange among tourmaline and coexisting minerals in metamorphosed pelites and graywackes, and in experimental exchange between tourmaline and biotite. In the natural samples, a temperature dependence of tourmaline Mg-Fe exchange with biotite, staurolite, garnet, chlorite, and muscovite, and Ca-Na exchange with plagioclase is observed. Equilibrium calculations for the complete mineral assemblage show that tourmaline is in compositional equilibrium with all coexisting phases, which would allow for an internally consistent set of thermometers among all these phases to be defined. However, a prohibitively large spread is present in the K D vs. T relations. This is not caused by analytical effects, compositional zoning, or disequilibrium among the minerals. The experimental results show that it is the result of inter-site partitioning of elements over the Y and Z octahedral sites of tourmaline. Variations in the element distribution over these sites, their relative participation in the exchange and differences in the temperature dependence of exchange with each site, strongly affects the K D vs. T relation observed, with the slope actually changing sign depending on the elements residing at each site. Non-ideal interactions among the elements at each site will also affect this, and furthermore link every exchange to the bulk tourmaline composition, and hence the element mobility in the rock. The promising potential of tourmaline geothermobarometry can therefore not be fulfilled until effects of inter-site partitioning and non-ideal interactions are known.

The preparation of dense, high-strength calcium phosphate-zirconia (CaP-ZrO2) composed bioceramics is realized via versatile pressureless sintering by adding silica nanoparticles. Two different weight ratios of HAp:ZrO2, 9:1 and 1:1, are used with varying silica contents from 5 to 20 wt%. After sintering at 1200 °C, the phase composition, microstructure, porosity, biaxial bending strength, and fracture toughness as well as SBF in vitro bioactivity are characterized. We show that the addition of silica altered the crystal phase composition, inhibiting the formation of non-favourable cubic ZrO2. Furthermore, SiO2 addition leads to an increase of the biaxial bending strength, and the fracture toughness of CaP-ZrO2-containing materials. With the addition of 20 wt% silica we find the highest characteristic strength (268 MPa) and toughness (2.3 ± 0.1 MPam(0.5)) at

The common serpentine–diopside matrix assemblage in volcaniclastic kimberlite (VK) at the Venetia Mine, South Africa is ascribed to a secondary origin, because of post-emplacement serpentinization and associated hydrothermal metamorphism. Volcaniclastic deposits with 20–30% porosity infill kimberlite pipes in the waning stages of kimberlite eruptions. Olivine macrocrysts are typically rimmed by talc and are pseudomorphed by lizardite, with minor magnetite. The fine matrix consists of mixtures of lizardite, chlorite, smectite, brucite, calcite, titanite and andradite, an assemblage which either pseudomorphed microcrysts or in-filled voids. Locally we recognize microcryst pseudomorphs rich in sub-microscopic mixtures of lizardite with smectite, and other microcryst pseudomorphs and void-filling matrix rich in chlorite and lizardite. Interstitial lizardite and associated phyllosilicates (brucite, smectite and chlorite) crystallized progressively from meteoric or hydrothermally derived pore waters, and Si4+ and Mg2+ released into the fluid phase during serpentinization of olivine macrocrysts. Radial-fibrous fringes of diopside microlites around crystals display void-filling textures because of unrestricted growth into pore spaces. Secondary diopside is attributed to Si4+, Mg2+ and Ca2+ cations released into the fluid phase by interaction with olivine, calcite and plagioclase in siliceous xenoliths. The paucity of primary, fine-grained groundmass phases resistant to alteration, for example, perovskite and spinel, precludes an origin for the intergrain matrix as altered interstitial ash, glass or a late-stage kimberlite melt. Isovolumetric replacement of olivine results in a volume increase of 60% so that pore spaces in the original deposit can be easily filled up with serpentine. The source of Al3+ to form chlorite and smectite is attributed to alteration of plagioclase in xenoliths which comprise 20–30 vol.% of the deposit. Titanite, hydro-andradite and second-generation diopside precipitate as hydrothermal minerals from calcium-bearing serpentinizing fluids in replacement reactions and as void-filling minerals. Consideration of mineral equilibria in the CaO-MgO-SiO2-H2O-CO2 system constrains the common matrix assemblage of lizardite and diopside in XCO2)–T space. At 300 bar, the assemblage is stable only at temperatures below 370 °C and XCO2

A mesoporous glassy carbon has been chemically (KOH) and physically (CO2) activated in order to improve its micropore volume while preserving the well-defined mesopore network. The microporosity of the glassy carbon and the evolution of the micropore texture with activation have been studied by means of Monte Carlo simulation and gas adsorption. Micropore size distributions obtained from simulated adsorption isotherms on slit-shaped pores revealed different accessibilities of methane and nitrogen to the microporous texture of the original sample, indicating the presence of constrictions in the micropore network. Both activating agents are able to increase the micropore volume generating new micropores, although KOH showed to be more effective. While CO2 treatment preserved some hindrances to the access of nitrogen molecules to the micropores, KOH activation generates a more accessible micropore network. Therefore, chemical activation by KOH is a suitable way to increase the adsorption capacity of glassy carbons while preserving the mesoporous structure. Molecular simulation of adsorption linked to experimental adsorption of different gases, has proven to give very satisfactory results in analysing the evolution of the micropore texture and accessibility of carbon materials by different activation treatments.

In this contribution a model for the elastic relaxation of Al0.5Ga0.5As and ZnSe wire structures, respectively, is presented. The wire structures extend along [110] and were characterized by high resolution x-ray diffraction experiments. Based on Monte Carlo simulations, the wire structures, which have been simulated at atomic resolution, were relaxed to reduce the strain caused by the lattice misfit. The x-ray diffraction patterns calculated for the final structures reproduce the observed data. The structures display a two dimensional strain gradient and curved lattice planes. Hence the introduced modeling is a powerful method in particular to resolve the atomic structure of a wet chemically etched or molecular beam epitaxial grown wire by giving a microscopic picture on an atomic scale.

We investigate molecular beam epitaxy of II-VI materials through GaAs/AlGaAs epitaxial shadow masks on GaAs(001) substrate. Scanning electron and atomic force microscopy are employed to investigate the effects of surface diffusion, faceting, partial shadow (minimized in the experimental set-up), and material deposition on the mask (closing of apertures) on the selected area growth of ZnSe and CdSe. The results illustrate that selected area growth of II-VI nanostructures is controlled by the growth geometry. In contrast to the case of III-V materials, we found no macroscopic features (>10 nm) which could be attributed to surface diffusion.

We present results on the elastic relaxation behaviour of II-VI and III-V wire structures. The structures were obtained by wet etching of extended layers as well as shadow mask assisted Selected Area Epitaxy (SAE). The SAE wire structures are especially interesting since they are grown directly, do not require treatment after the growth process, and posess the ability to relax elastically during growth. Reciprocal space maps of strained semiconductor structures, obtained by High Resolution X-ray Diffraction (HRXRD) have so far been interpreted in the context of bulk elastic properties. In this contribution we introduce a relaxation procedure based on interatomic potentials. The wire structure is simulated with atomic resolution atop of the substrate material. A Monte-Carlo algorithm is applied to relax the structure while minimizing the strain energy. The reciprocal space maps calculated from the relaxed structure are in good agreement with the observed HRXRD maps. Hence we can interprete the strain state of the wire structures with atomic resolution. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Numerous rod-shaped calcite crystals occur in the blueschist to eclogite facies marbles of Syros, Greece. The rods show a shape-preferred orientation, and the long axes of the rods are oriented at a large angle to foliation. The crystals also have a crystallographic-preferred orientation: calcite c-axes are oriented parallel to the long axes of the rods. Based on their chemical composition, shape, and occurrence in high-pressure marbles, these calcite crystals are interpreted as topotactic pseudomorphs after aragonite that developed a crystallographic-preferred orientation during peak metamorphism. This interpretation is consistent with deformation of aragonite by dislocation creep, which has been observed in laboratory experiments but has not been previously reported on the basis of field evidence. Subsequent to the high-pressure deformation of the aragonite marbles, the aragonite recrystallized statically into coarse rod-shaped crystals, maintaining the crystallographic orientation developed during deformation. During later exhumation, aragonite reverted to calcite, and the marbles experienced little further deformation, at least in the pseudomorph-rich layers. Some shearing of pseudomorph-bearing marble layers did occur and is indicated by twinning of calcite and by a variable inclination of the pseudomorphs relative to foliation.

We have investigated the underlying electronic and structural effects of the previously published influence of a Te substrate pretreatment on the heterovalent ZnSe/GaAs(1 0 0) interface [Appl. Phys. Lett. 78 (2001) 1867]. For this purpose, photoelectron spectroscopy and density functional theory calculations were employed. To determine the valence band maximum accurately, the choice of suitable photon energies to maximize the contribution from the Cpoint as well as a variation of the k-vector by measuring under selected angles is investigated. We discuss the resulting band offsets with respect to the atomic interface structure and to the broadening of core level line shapes. The theoretical investigations focus on the effect of replacing Se by Te atoms at the interface, particularly in view of the lattice structure and the band offsets. We find that Te helps to establish a group-VI-rich interface, thus lowering the valence band offset, while maintaining a good crystal quality by acting as a diffusion barrier for Se atoms. 2003 Elsevier Science B.V. All rights reserved.

We investigate the geometric deposition of compound semiconductors through shallow shadow masks as a means to obtain 3D nanostructures in situ. A high spatial resolution in the order of 10 nm and good material quality are achieved by epitaxy with directed molecular beams through stationary masks. Based on our study of growth dynamics new processes were tailored for the deposition of compound semiconductors. These expand the degrees of freedom of directional shadow growth. We would like to give an overview of this alternative technology, and present late results from experiments with an optimised molecular beam epitaxy (MBE) set-up. Projective techniques are demonstrated with sample structures. We discuss their respective potential and limitations. An outlook shows the perspective of further increase of the complexity of feasible structures by increasing the complexity of the masks (3D nanostructured).

In this paper we present results from the molecular simulation of water adsorption in slit-shaped activated carbon pores. We calculate adsorption isotherms by grand canonical Monte Carlo (GCMC) simulation, Henry's constants by Monte Carlo integration, and vapor-liquid equilibrium data by the gauge-cell Monte Carlo method, to investigate the chemical heterogeneity of activated carbon adsorbents. Several types of polar oxygen-containing sites are placed on the surface of the carbon with different densities and local distributions, in order to determine the individual effects of each of these factors on the adsorption of water. Our results confirm the role of surface sites in the enhancement of water adsorption, Furthermore, we show that the local distribution of these sites has a strong effect on low-pressure adsorption, while the overall site density affects mainly the vapor-liquid phase transition. The type of oxygen-containing group is shown not to be of critical importance, since more complex groups can effectively be represented by simpler sites. This study forms the basis for the development of a model for activated carbon that is able to represent the chemical heterogeneity of this type of material.

Thin pseudomorphic ZnSe films can be grown by molecular beam epitaxy on GaAs(001) up to a layer thickness of about 100 nm. Above this critical thickness the topmost layers relax by forming large mosaic-domains which are tilted by 0.2° with respect to the macroscopic surface. This is evidenced by satellites arising in discrete directions close to the fundamental diffraction spots in high resolution low energy electron diffraction (SPA-LEED). Energy dependent SPA-LEED measurements were performed to characterize the satellites and identify their origin. High resolution X-ray diffraction (HRXRD) experiments indicate that this mosaicity is restricted to a near-surface region and does not penetrate deeply into the bulk of the ZnSe film.

Ca3ZrSi2O9 (baghdadite) has become a major research focus within the biomaterial community due to its remarkable in-vitro and in-vivo bioactivity. Although baghdadite seems to exhibit interesting biological properties, as yet there has been no data published concerning its mechanical properties. This lack of knowledge hinders targeting this novel bioactive material towards potential applications. In this study we prepare dense Ca3ZrSi2O9 bulk ceramics for the first time, allowing the evaluation of its mechanical properties including hardness, bending strength, Young׳s modulus, and fracture toughness. The preparation of baghdadite has been accomplished by a direct solid-state synthesis in combination with conventional sintering at 1350-1450°C for 3h. Our results show that samples sintered at 1400°C exhibit the best mechanical properties, resulting in a bending strength, fracture toughness, and hardness of 98±16MPa, 1.3±0.1MPam(0.5), and 7.9±0.2GPa. With a comparable mechanical strength to hydroxyapatite, but with an increased fracture toughness by 30% and hardness by 13% baghdadite is highly suitable for potential applications in non-load bearing areas (e.g. coatings or filler materials).

We present a novel method to grow sharply defined self-organized nanostructures into UHV-compatible Al 50 Ga 50 As-GaAs shadow masks. The lateral control of epitaxial growth is achieved by self-organized as well as the masks’geometry. We show that we obtain prism-shaped wire structures with triangular cross sections. These wires exhibit well-defined (1 1 1) side faces due to the effect to self-organized growth. Furthermore, we demonstrate the achievement of lateral carrier confinement with this technique.

This contribution reports about the first in situ lateral structured II–VI semiconductors grown with molecular beam epitaxy into Al 50 Ga 50 As–GaAs shadow masks. The lateral control is achieved by tilting the sample manipulator with respect to the molecular beam emanated by the effusion cells. Thus wire structures can be grown whose width depends on the angle of flux incidence and the shadow mask geometry. It is shown that lateral carrier confinement can be achieved with this technique.

This paper presents high-resolution x-ray diffraction measurements of shadow masks. Shadow masks are used for in situ growing of one- and zero-dimensional semiconductor heterostructures. The masks are produced by selective etching of AlxGa1-xAs-GaAs heterostructures. The lateral dimension of these structures is in the range 10-300 µm; the thickness of the constituting layer varies between 1 and 10 µm. Structures with linear and crossgrid patterns have been measured. The reciprocal space maps of the initial structures show a distortion of the whole sample by the strain of the AlxGa1-xAs layer. After processing, this strain is reduced by an elastic relaxation of the parallel lattice constant. The three-dimensional masks lead to complicated intensity distributions in reciprocal space. The different contributions to the reciprocal space maps are identified by measuring symmetrical and asymmetrical reflections of specially designed structures. This knowledge is useful for the interpretation of the reciprocal space maps of other three dimensional samples, such as semiconductor devices.

We propose a new method to obtain well defined nanostructures in situ during MBE growth. The method is based on the MBE growth over UHV compatible shadow edges. These edges define a geometrical shadow region which can be modified by tilting the sample with respect to the direction of the molecular beams, so that layers with different lateral extension can be combined to form a buried junction of two quantum wells in the form a wire with lateral confinement. We show for ZnSe quantum wells in ZnMgSSe that the formation of facets at the shadow edge favours the formation of geometrically well defined structures, and quantum well junctions as narrow as 150 nm have been realized. The wires emit pronounced blue cathodoluminescence at room temperature, proving that even for simple structures the confinement of carriers in the resulting wire is on the order of kT at room temperature.

ZnSe p-i-n-type photodiodes were grown on GaAs substrates using molecular beam epitaxy technique. ZnCl 2 was used for n-doping and plasma-excited N 2 for p-doping. The p-side contact consists of 200 nm Au in situ deposited on a 20 nm highly doped ZnTe layer on top of the p-doped ZnSe forming a well-defined Schottky barrier, as can be confirmed by current - voltage measurements together with an electrical model of the diode. Reverse-bias photocurrent was measured as a function of wavelength. The spectral responsivity is about 30 mA (WeV) at the band edge which corresponds to a quantum efficiency of roughly 8%. Calculations of the spectral response were performed using a modified model originally designed on Si solar cells and reflectivity data determined by ellipsometry. The comparison of the model with measurements indicates that the photocurrent is dominated by the drift current generated within the space-charge region.

ZnTeZn(S,Te) short-period superlattices have been grown on (0 0 1) GaAs-substrates with very good structural quality. The growth conditions were found to be quite reproducible, leading to a series of samples with periods between 12 and 29 A. Characterisation of the samples with high-resolution X-ray diffraction confirmed the high structural quality of the structures, showing that all samples are pseudomorphically grown. The relaxation behaviour is strongly influenced by the ZnTe-well width with two critical ZnTe-thicknesses observable.

The energy gap of zinc-blende epitaxial layers grown by molecular beam epitaxy has been determined over a wide range of composition using optical transmission and reflection and an empirical formula for the energy gap at room temperature is also given. In addition in situ spectroscopic ellipsometry was used in order to determine the temperature dependence of the energy gap between room temperature and the growth temperature of alloys with compositions x, y as used in cladding layers and waveguides for blue - green light-emitting devices.

For the heterovalent system ZnSe/GaAs(100), we have investigated the influence of a Te pretreatment of the substrate on the electronic structure of the interface by photoelectron spectroscopy. We have paid special attention to correctly determine the valence band maximum in a k-resolved fashion, including the use of photon energies which enable excitation at the Γ point. We find that the Te pretreatment leads to a decrease of the valence band discontinuity as large as 0.3 eV. From photoemission depth profiling we conclude that some Te atoms remain localized at the interface, thus causing the change of the valence band offset while others float on the ZnSe surface, probably acting as surfactants.

Högbomite is reported from two upper-amphibolite and granulite-facies, sapphirine-bearing, Al–Mg–Fe-rich and silica-poor lens-shaped layers within the Bamble Sector, south Norway. Primary assemblages, indicating peak metamorphic conditions of 773-844°C at 7 kbar (Mg–Fe exchange thermometry), are spinel–sapphirine–biotite–gedrite, spinel–corundum–sapphirine–cordierite and orthopyroxene–biotite–cordierite–plagioclase. Högbomite formed by hydrous alteration and oxidation of primary spinel and rutile and/or ilmenite according to the generalised reaction:Suggested conditions of högbomite formation are 550–620°C and 6–7 kbar. The högbomites contain 10.2–14.7 wt.% MgO, 04).3 wt.% ZnO, 58.9–62.1 wt.% Al2O3 and 15.6-17.6 wt.% Fe as FeO. The two högbomite may belong to different polytypes, as suggested by their differing TiO2 (9.9-10.1 versus 5.7–5.8 wt. %) and calculated Fe3+ – and H2O–contents. The partitioning of Zn between spinel and högbomite is not uniform and is considered to depend upon prevailing fo2 and aH2O.

IP-10, a small, gamma-interferon-inducible protein with structural homology to interleukin-8 (IL-8), was prepared by automated chemical synthesis and compared with synthetic IL-8, GRO alpha and neutrophil-activating peptide 2 (NAP-2) for neutrophil stimulating activity. The following functions were tested: cytosolic free calcium changes, chemotaxis in vitro, respiratory burst, exocytosis of azurophil and specific granules from cytochalasin B-pretreated cells, and competition for IL-8 receptor binding. At 1, 10, 100 and 1000 nM, IP-10 was inactive in all assays, in contrast to the reference peptides which exhibited the expected neutrophil stimulating effects. In addition, IP-10 did not induce neutrophil accumulation after intradermal injection in rats, and did not act as IL-8 antagonist.

The adsorption of N2 and CO2 in the microporous aluminium methylphosphonate polymorphs alpha and beta is investigated by adsorption experiments in combination with Monte Carlo (MC) simulations. We find that close steric matching of N2 and polymorph alpha causes a packing transition not observed for the other pairs of adsorbate and adsorbent. This strong effect on adsorption behaviour of small differences in the adsorbent structure and adsorbent-adsorbate interactions suggests that microporous, hybrid inorganic organic materials of this type offer opportunities for highly selective adsorptive separations. The realism of the MC simulations is extraordinarily dependent upon the molecular size parameters used.

The ferromagnesian silicate minerals, such as garnets, pyroxenes, micas, and amphiboles, appear in a variety of geothermometers and geobarometers. Where complete chemical analyses are available and regardless of bulk composition (metamorphosed pelitic or mafic), the aforementioned minerals commonly contain ferric iron. In mineral analyses using the electron microprobe, ferric and ferrous iron are not distinguished, and all the iron is treated as FeO. In ferric Fe-bearing minerals, this treatment results in (1) low analytical sums and (2) excess cations in the mineral formulae. Assuming ideal stoichiometry (ideal formula cations and oxygens) allows direct ferric estimates in garnets and pyroxenes; amphiboles require additional assumptions concerning site occupancies, and, for micas, no acceptable constraint exists for a ferric estimate. Based on ferric iron determinations for some metamorphic ferromagnesian silicates, the proportion of ferric to total iron increases at higher XMg values. The influence of ferric estimates on T and P calculations depends on the model used and on the extent the ferric estimate alters the relative proportions of end-members. Several examples suggest that, in general, if ferric estimates (or determinations) are made, they should be made for all the relevant minerals.

Cobalt oxide films, fabricated by reactive sputtering in a 100% pure O 2 plasma are highly nonstoichiometric with a bulk oxygen to cobalt ratio of ∼ 1.15. Conversely, surface XPS studies indicate an oxygen to cobalt ratio ranging from 1.8 to 3.0 and show the presence of Co 3+ only in the surface region of the as formed films. Infrared and Raman spectra however confirm the presence of both Co 3+ and Co 2+ in the bulk and indicate that these highly defective films possess the spinel structure. Photoelectrochemical and impedance studies show that the sputtered oxide is a highly doped p-type semiconductor with an indirect bandgap of E g ∼ 1.50 eV. The electrocatalytic properties of these oxide films for oxygen reduction and evolution are reported.

Oxygen photoanodes formed by reactive sputtering of iron oxide onto conducting indium tin oxide (ITO) substrates held at 350 ° C have been investigated by conventional photoelectrochemical, impedance, XPS and auger spectroscopic methods. This fabrication procedure leads to films containing 8 to 20 atomic % indium in the front portion of the film, increasing to much higher values near the ITO interface (back portion of the film). Two interesting effects are observed with the thin-film iron oxide formed in this way. The first is that the as formed films must be vacuum annealed before an appreciable dc photoanodic response is observed. Secondly, films 250 nm thick display the property of giving about double the quantum yield for back face, than for front face, illumination over the spin and parity forbidden transition centered at 535 nm. On correcting for transmission and reflection losses, the resulting true quantum efficiencies satisfy the same inequality, a result that can only be accounted for by a higher ( > 2 × ) primary quantum efficiency for the back, versus the front portion of the film. As these films show substantially higher quantum efficiencies than do indium free films of the same thickness, it is concluded that the indium in the films is responsible for the increase in primary quantum efficiency. This result is discussed in terms of a localized states model for α-Fe2O3.

Accessory phases and minor components in minerals are commonly ignored in thermodynamic modelling. Such an approach seems unwarranted, as accessory phases can represent a significant element reservoir and minor components can substantially change their host mineral's stability field. However, a lack of thermodynamic data prohibits assessment of these effects. In this contribution, the polyhedron method is used to estimate the thermodynamic properties of tourmaline, a common and widespread accessory phase, stable over a range of P-T-X conditions. The polyhedron method allows Δ H, S, V, Cp and Vm (T, P) properties to be estimated from a linear stoichiometric summation over the fractional properties of its polyhedron constituents. To allow for estimates of tourmaline, fractional thermodynamic properties for B III and B IV polyhedra were derived. Mixing contributions to molar volume were evaluated and symmetrical mixing parameters derived for Al-Mg, Al-Fe and Al-Li interaction on tourmaline's Y-site and T-site Al-Si interaction. Evaluation of the estimated properties using experimental and natural equilibria between tourmaline and melts, minerals and hydrothermal fluids, shows that reliable semi-quantitative results are obtained. The boron contents in fluids coexisting with tourmaline are calculated to within an order of magnitude of measured content, and where anchor-points are available, agreement improves to within a factor of 2. Including tourmaline in petrogenetic modelling of metamorphic rocks indicates that its presence leads to disappearance of staurolite and garnet, among others, and modifies the XMg of coexisting phases, in line with observations on natural rocks. © 2007 Blackwell Publishing Ltd.

For the first time the successful preparation of Sr doped baghdadite (Ca3-x Sr x ZrSi2O9 x = 0.1 and 0.75) is shown. Sr-doped as well as pure baghdadite are prepared via a versatile solid-state synthesis and conventional sintering at 1400 °C. XRD measurements and crystal structure refinements reveal that a substitution of Ca atoms with Sr and a high purity (>99%) is achieved. The physical, mechanical, and biological properties of these novel bioceramics are presented in relation to the dopant concentration. Incorporating Sr into the baghdadite crystal caused only minor changes to the grain size and the mechanical properties. The characteristic strength ranges from 145 to 168 MPa and a Weibull modulus of 4.9 to 9.2 is observed. Other mechanical properties like fracture toughness and hardness vary from 1.23 ± 0.07 MPam(0.5) to 1.31 ± 0.12 MPam(0.5) and 7.3 ± 0.6 GPa to 8.0 ± 0.7 GPa, respectively. The in vitro cellular response of human osteoblasts showed an increase in the cell proliferation and a significantly higher alkaline phosphatase (ALP) activity with an increase in the Sr content. From the improved biological properties and the suitable mechanical performance we conclude that this material is a highly promising candidate for bone replacement material and bioactive implant coatings.

The expression of membrane proteins for functional and structural studies or medicinal applications is still not very well established. Membrane-spanning proteins that mediate the information flow of the extracellular side with the interior of the cell are prime targets for drug development methods that would allow screening techniques or high throughput formats are of particular interest. Here we describe a systematic approach to the liposome-assisted cell-free synthesis of functional membrane proteins. We demonstrate the synthesis of bacteriorhodopsin (bR(cf)) in presence of small unilamellar liposomes. The yield of bR(cf) per volume cell culture is comparable to that of bacteriorhodopsin in its native host. The functional analysis of bR(cf) was performed directly using the cell-free reaction mixture. Photocycle measurements reveal kinetic data similar to that determined for bR in Halobacterium salinarum cell-envelope vesicles. The liposomes can be attached directly to black lipid membranes (BLM), which allows measuring light activated photocurrents in situ. The results reveal a functional proton pump with properties identical to those established for the native protein.

This paper represents a practical guide to ligand receptor binding studies with special emphasis on the detailed characterization of radiolabeled ligands prior to receptor binding experiments. The effects due to labeled ligand inactivated by the labeling procedure are included. The inactive ligand may contribute as much as the active ligand to nonspecific binding. A method for measuring the fraction of active ligand in the initial sample and for determining the specific radioactivity and bindability is presented in detail. A straightforward procedure for extracting the concentration of bound and free active ligand from the measured crude binding data is then presented. The dissociation constant and the number of receptors are obtained by fitting the binding equation to the free and bound ligand concentrations. As a practical example, interleukin-8 binding to human neutrophils was used. The experiments are discussed with respect to possible errors, and specific conditions (concentrations of ligand and receptors) necessary for accurate determination of the respective binding parameters are given.