X-ray grating interferometer for materials-science imaging at a low-coherent wiggler source

X-ray phase-contrast radiography and tomography enable to increase contrast for weakly absorbing materials. Recently, x-ray grating interferometers were developed that extend the possibility of phase-contrast imaging from highly brilliant radiation sources like third-generation synchrotron sources to non-coherent conventional x-ray tube sources. Here, we present the first installation of a three grating x-ray interferometer at a low-coherence wiggler source at the beamline W2 (HARWI II) operated by the Helmholtz-Zentrum Geesthacht at the second-generation synchrotron storage ring DORIS (DESY, Hamburg, Germany). Using this type of the wiggler insertion device with a millimeter-sized source allows monochromatic phase-contrast imaging of centimeter sized objects with high photon flux. Thus, biological and materials-science imaging applications can highly profit from this imaging modality. The specially designed grating interferometer currently works in the photon energy range from 22 to 30 keV, and the range will be increased by using adapted x-ray optical gratings. Our results of an energy-dependent visibility measurement in comparison to corresponding simulations demonstrate the performance of the new setup.     

Crystallization and microstructural evolution of MgO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript>–La<Subscript>2</Subscript>O<Subscript>3</Subscript> glass-ceramics

Crystallization and microstructure of glasses with the molar compositions 1MgO·1.2Al₂O₃·2.8SiO₂·1.2TiO₂·xLa₂O₃ (x = 0.1 and 0.4) were thermally treated at different temperatures in the range from 950 to 1250 °C and then analyzed by X-ray diffraction and scanning electron microscopy, in combination with energy-dispersive X-ray spectroscopy and electron backscatter diffraction. It was found that the microstructure is first homogeneous with the precipitation of randomly distributed crystals and then indialite domains with embedded perrierite and rutile crystals are formed. For higher temperatures or prolonged times, more domains appear and expand into the bulk of the sample. Finally, the entire sample consists of the indialite domains and the boundaries that are enriched in rutile, perrierite, and magnesium aluminotitanate. Nevertheless, very distinct differences are observed between the samples with different La₂O₃ concentrations. For the sample with x = 0.4, the domains were detected at lower temperatures, while the quantity and size of the domains increase faster due to the promoted precipitation of indialite. For the sample with x = 0.1, in addition to the domain boundaries, secondary boundaries between the “regions” (assemblages of the domains) are observed in a larger length scale. The average size of the crystalline phases found between the “regions” is larger than that typically observed at the domain boundaries. The sizes of the crystals at the boundaries decrease with higher concentrations of La₂O₃, and the crystals (especially perrierite) within the domains become larger, resulting in a more homogeneous microstructure. This results in better dielectric properties, i.e., much higher quality factor for the sample with x = 0.4 in comparison to that with x = 0.1 after heat-treatment at 1150 or 1250 °C.     

Optical and magnetic resonance imaging of cell death and platelet activation using annexin a5-functionalized quantum dots

A quantum-dot-based nanoparticle is presented, allowing visualization of cell death and activated platelets with fluorescence imaging and MRI. The particle exhibits intense fluorescence and a large MR relaxivity (r1) of 3000-4500 mM-1 s-1 per nanoparticle due to a newly designed construct increasing the gadolinium-DTPA load. The nanoparticle is suitable for both anatomic and subcellular imaging of structures in the vessel wall and is a promising bimodal contrast agent for future in vivo imaging studies.     

HeLa cell transfection using a novel sonoporation system

Sonoporation has been shown to have an important role in biotechnology for gene therapy and drug delivery. This paper presents a novel microfluidic sonoporation system that achieves high rates of cell transfection and cell viability by operating the sonoporation chamber at resonance. The paper presents a theoretical analysis of the resonant sonoporation chamber design, which achieves sonoporation by forming an ultrasonic standing wave across the chamber. A piezoelectric transducer (PZT 26) is used to generate the ultrasound and the different material thicknesses have been identified to give a chamber resonance at 980 kHz. The efficiency of the sonoporation system was determined experimentally under a range of sonoporation conditions and different exposures time (5, 10, 15, and 20 s, respectively) using HeLa cells and plasmid (peGFP-N1). The experimental results achieve a cell transfection efficiency of 68.9% (analysis of variance, ANOVA, p < 0.05) at the resonant frequency of 980 kHz at 100 V(p-p) (19.5 MPa) with a cell viability of 77% after 10 s of insonication.     

Methanation in a fluidized bed reactor with high initial CO partial pressure: Part I—Experimental investigation of hydrodynamics, mass transfer effects, and carbon deposition

An extensive experimental study on the methanation reaction was carried out in a gas–solid fluidized bed reactor at 320 °C with a stoichiometric ratio of H₂/CO=3. By means of spatially resolved measurements of the axial gas species concentration and temperatures along the fluid bed the effects of different catalyst loadings, gas velocities and dilution rates were observed and analyzed. By applying this technique, it was found that most of the reaction (CO and H₂ conversion) proceeds in the first 20 mm of the bed depending on the experimental conditions. For a few cases, the temperature increases by up to 80 °C from 320 to 400 °C within the first 3 mm of the bed. By increasing the inlet volume flow only by a factor of 1.4, the temperature hotspot diminishes and isothermal behavior develops. For all experiments, a CO conversion of practically 100% was achieved. The experimental data indicate that the dense phase of the fluidized bed is probed and that mass transfer between bubble and dense phase is dominating in the upper part of the bed. It could be shown that both hydrodynamic and chemical boundary conditions influence the methanation reaction inside the fluidized bed reactor.     

The impact of sulfur on the performance of a solid oxide fuel cell (SOFC) system operated with hydrocarboneous fuel gas

The impact of thiophene in the fuel gas of a commercial solid oxide fuel cell (SOFC) system is investigated for concentrations up to 400 ppmV. Based on the measured voltage–current curves, an empiric correlation for the estimation of the expectable power output of the investigated SOFC system when operated with sulfur containing fuel gases is derived. An interrelation between the open circuit voltage (OCV) and the sulfur concentration of the investigated hydrocarboneous fuel gas is presented and discussed based on corresponding model simulations. The reduction of the steam reforming (STR) activity of the anode cermet material and of the catalytic partial oxidation catalyst used for the fuel gas processing in the investigated SOFC system are found important factors regarding the power output reduction induced by sulfur traces in the fuel gas of SOFCs.     

纽马格推动客户BCF生产

地毯和地毯纱市场总是充满着挑战,新的需求不断地出现。地毯业的时尚潮流在快速地变化着,同时全球性的压力也在稳步增长。地毯业在这样的竞争环境中必须找到能够保持成功的途径。在这种情况下．工艺链前期的BCF技术对地毯纱和地毯生产是否成功起着决定性的作用。     

High-Temperature Proton Conductors for the Injection of Hydrogen into a Vacuum

Tubes of ceramic high-temperature proton conductors (CaZr_0.9In_0.1O_{3− x} ,BaZr_0.9Y_0.1O_{3− x} , and Ba₃Ca_1.18Nb_1.82O_{9− x} )were used to introduce hydrogen into a vacuum system. A prerequisite was a leak rate below 10⁻⁸mbar/s for an assembly consisting of the active tube and a 8YSZ support tube. Mass spectrometry showed that the partial pressure of hydrogen in the vacuum system, p _H2, increased linearly with the electric current flowing through the proton conductor. All other important partial pressures remained unaffected by this operation. Calculation of throughput during operation of the hydrogen source essentially revealed that the total current, J , is used to transport protons from the anode to the cathode ( t _H∼ 1). The number of moles of H₂ transported per second is given by J /2 F . In essence, the present proton conductor tube constitutes a precise, current-controllable device, with a response time of a few seconds only, that delivers ultrahigh-purity hydrogen to a vacuum system.