Formation and Stability of β-Quartz Solid-Solution Phase in the Li-Si-Al-O-N System

The development of crystalline phases in lithium oxynitride glass-ceramics was examined, with particular emphasis placed on the effect of the nitrogen source (AlN or Si₃N₄) on the formation and stability of a β-quartz solid-solution ( ss ) phase. Oxynitride glasses derived from the Li-Si-Al-O-N system were heat-treated at temperatures up to 1200°C to yield glass-ceramics in which β-quartz( ss ) and β-spodumene( ss ) of approximate composition Li₂OAl₂O₃4SiO₂ formed as major phases and in which X-phase (Si₃Al₆O₁₂N₂) and silicon oxynitride (Si₂N₂O) were present as minor phases. The nitrogen-containing β-quartz( ss ) phase that was prepared with AlN was stable at 1200°C; however, the use of Si₃N₄ as the nitrogen source was significantly less effective in promoting such thermal stabilization. Lattice parameter measurements revealed that AlN and Si₃N₄ had different effects on the crystalline structures, and it was proposed that the enhanced thermal stability of the β-quartz( ss ) phase that was prepared with AlN was due to both the replacement of oxygen by nitrogen and the positioning of excess Al³⁺ ions into interstitial sites within the β-quartz( ss ) crystal lattice.     

A global NDVI and EVI reference data set for land-surface phenology using 13 years of daily SPOT-VEGETATION observations

Time series of vegetation indices (VIs) obtained by remote sensing are widely used to study phenology on regional and global scales. The aim of the study is to design a method and to produce a reference data set describing the seasonal and inter-annual variability of the land-surface phenology on a global scale. Specific constraints are inherent in the design of such a global reference data set: (1) the high diversity of vegetation types and the heterogeneous conditions of observation, (2) a near-daily resolution is needed to follow the rapid changes in phenology, (3) the time series used to depict the baseline vegetation cycle must be long enough to be representative of the current vegetation dynamic and encompass anomalies, and (4) a spatial resolution consistent with a land-cover-specific analysis should be privileged. This study focuses on the SPOT (Satellite Pour l’Observation de la Terre)-VEGETATION sensor and its 13-year time series of reflectance values. Five steps addressing the noise and the missing data in the reflectance time series were selected to process the daily multispectral reflectance observations. The final product provides, for every pixel, three profiles for 52 × 7-day periods: a mean, a median, and a standard deviation profile. The mean and median profiles represent the reference seasonal pattern for variation of the vegetation at a specific location whereas the standard deviation profile expresses the inter-annual variability of VIs. A quality flag at the pixel level demonstrated that the reference data set can be considered as a reliable representation of the vegetation phenology in most parts of the Earth.     

Electrical resistivity and hydrogen solubility of PdHc thin films

During hydrogen gas loading, Pd thin films exhibit an anomalous reduction of resistivity change with decreasing film thickness. In this paper we show that this effect can mainly be attributed to a stress-dependent reduction of hydrogen solubility at a given hydrogen pressure. Different stress states of the thin films result from different bonding to a rigid substrate. Strongly buckled thin films show bulk-like pressure–resistivity isotherms. The resistivity changes as a function of hydrogen concentration appear to be independent of film thickness. The apparent Sieverts’ constant seems to be larger for thin films compared to bulk, and increases with cycling of the thin films.     

Development of a PM 10/PM 2.5 Cascade Impactor and In-Stack Measurements

Combustion and industrial processes are an important source of particles. Due to the new PM 10 and PM 2.5 standards for ambient air quality, a sampling system for PM 10/PM 2.5 in-stack measurements was designed and calibrated. In this new system, the exhaust gas is isokinetically sucked into a two stage impactor through the inlet of a plane filter device and the aerosol is fractionated in the particle size classes >10 w m, 10-2.5 w m, and <2.5 w m. Due to a relatively high volume flow (ca. 3.2 m 3 /h, depending on exhaust gas conditions), sampling times are kept short, e.g., 30 min for dust concentrations of 10 mg/m 3 . The impactor was calibrated in the laboratory and then operated at various industrial plants. Parallel measurements with identical devices showed average standard deviations of 3.1% (PM 10) and 3.4% (PM 2.5). Measurements of the cascade impactor together with the plane filter device gave plausible results and average PMx/TSP ratios of 0.49 (PM 2.5/TSP) and 0.78 (PM 10/TSP), showing a large variability for different processes. Elemental analysis using total-reflection X-ray fluorescence spectrometry, together with the size-fractionated sampling, proved to give characteristic patterns of the emitted aerosols, which can be used for a subsequent fingerprint modelling for source apportionment of ambient air pollution.     

Artificial photosynthesis at soft interfaces

The concept of artificial photosynthesis at a polarised liquid membrane is presented. It includes two photosystems, one at each interface for the hydrogen and oxygen evolution respectively. Both reactions involve proton coupled electron transfer reactions, and some ultrafast steps at the photosensitization stage.     

Acute Myelogenous Leukemia Cells Secrete Factors that Stimulate Cellular LDL Uptake via Autocrine and Paracrine Mechanisms

Leukemic cells isolated from most patients with acute myelogenous leukemia (AML) have higher low density lipoprotein (LDL) uptake than normal mononuclear blood cells. Little is known, however, about the mechanism behind the elevated LDL uptake. We investigated if AML cells secrete factors that stimulate cellular LDL uptake. Mononuclear blood cells were isolated from peripheral blood from 42 patients with AML at diagnosis. Cellular LDL uptake was determined from the degradation rate of ¹²⁵I-labelled LDL. Conditioned media from AML cells stimulated the LDL degradation in the leukemic cell lines KG1 and HL60, and in isolated AML cells. The stimulatory effect correlated with the LDL degradation in the AML cells directly after isolation from blood. Conditioned media also autostimulated LDL degradation in the AML cells themselves. Concentrations of IL-6 and IL-8 in AML cell conditioned media correlated with the LDL degradation in AML cells directly after isolation from blood. Addition of R-TNF-α, but not IL-6 or IL-8, stimulated LDL degradation in HL60, KG1, and AML cells. The LDL degradation in AML cells could be inhibited by a LDL receptor blocking antibody. AML cells secrete factors that stimulate LDL uptake in a paracrine and autocrine pattern which open up therapeutic possibilities to inhibit the uptake of LDL by administration of antibodies to these factors.     

Biaxial strength and slow crack growth in porous alumina with silica sintering aid

Biaxial strength, fracture toughness and subcritical crack growth are reported for coarse grained porous alumina ceramics. The materials were prepared with a varying amount of a silica sintering aid, which resulted in the formation of a glassy secondary phase at the grain boundaries. Crystalline mullite was additionally found in the material with the highest silica content. The biaxial strength, measured by Ball-on-Ring and Ball-on-3-Balls, was highest for the material without mullite at the grain boundaries, and the biaxial strength decreased with increasing porosity. The fracture toughness of the materials was in the range of 1.7–1.9 MPa m^0.5. Measurements of subcritical crack growth by a modified lifetime method in air and aqueous environments demonstrated a higher crack growth rate in water and acid relative to in air. The effect of porosity and grain boundary phase were discussed in relation to subcritical crack growth and fracture mode in the coarse grained alumina ceramics.     

Crack Patterns in Thin Polymer Layers

Summary: During the solidification of thin polymer layers different crack patterns can occur. There are several mechanisms of the development of regular crack defects and layer fractures. In case of self‐organization caused by Marangoni instability at the fluid layer surface the substrate can be periodically uncovered by spreading motions when dewetting hinders a back flow from the higher spots of the layer. Another type of crack patterns is generated from shrinkage processes and stress differences in the drying layer. Mostly these patterns are characterized by intersecting straight cracks. In this paper some examples of unusual shrinkage‐crack patterns in polymer layers are presented. Their propagation is independent on surface flow and surface deformations caused by the Marangoni effect, although the strength of polymer layers is impaired by the interfacial instability. Especially at layer edges or spots with thickness differences one can observe periodic wavy or circularly bend shrinkage‐crack structures. As a third type ramified surface defects are studied in thin layers. Often they only propagate at the layer surface.

Wavy shrinkage‐cracks in a PMMA layer with longish surface elevations.     

Site‐Specific Labelling of Native Mammalian Proteins for Single‐Molecule FRET Measurements

Human cells are complex entities in which molecular recognition and selection are critical for cellular processes often driven by structural changes and dynamic interactions. Biomolecules appear in different chemical states, and modifications, such as phosphorylation, affect their function. Hence, using proteins in their chemically native state in biochemical and biophysical assays is essential. Single‐molecule FRET measurements allow exploration of the structure, function and dynamics of biomolecules but cannot be fully exploited for the human proteome, as a method for the site‐specific coupling of organic dyes into native, non‐recombinant mammalian proteins is lacking. We address this issue showing the site‐specific engineering of fluorescent dyes into human proteins on the basis of bioorthogonal reactions. We show the applicability of the method to study functional and post‐translationally modified proteins on the single‐molecule level, among them the hitherto inaccessible human Argonaute 2.     

7 Themes for guiding situated ergonomic assessments of medical devices: A case study of an inpatient glucometer

There is relatively little guidance on the situated ergonomic assessment of medical devices, and few case studies that detail this type of evaluation. This paper reports results of a detailed case study that focuses on the design and use of a modern blood glucose meter on an oncology ward. We spent approximately 150 h in-situ, over 11 days and 4 nights, performing observations and interviews with users. This was complemented by interviews with two staff with oversight and management responsibility related to the device. We identified 19 issues with the design and use of this device. These issues were grouped into 7 themes which can help guide the situated study of medical devices: usability, knowledge gaps and mental models, workarounds, wider tasks and equipment, the patient, connection between services, and policy.