Rotationally controlled magneto-hydrodynamic particle handling for bead-based microfluidic assays

This work presents a novel magnetic actuation scheme for advanced particle handling on our previously introduced, centrifugal microfluidic platform for array-based analysis of individual cells and beads. The conceptually simple actuation is based on the reciprocating motion of an elastomeric membrane featuring an integrated permanent magnet and a stationary magnet aligned along the orbit of a disc-based chamber. This compression chamber is placed at the downstream end of the particle capture chamber to induce centripetally directed, hydrodynamic lift forces on particles trapped in V-shaped geometrical barriers. Towards high frequencies of rotation, the on-disc magnet ceases to follow the rapidly oscillating magnetic field, so that the magnetic actuator is disabled during the initial, sedimentation-based filling of the trap array. At reduced spin speeds, the residence time of the magnetic actuator is sufficient to displace the magnetic actuator, resulting in a flow through the V-cup array that re-distributes, and eventually fully depletes, the previously trapped beads from the array. The same magnetic deflection scheme is also demonstrated to accelerate mixing, e.g. for upstream sample preparation.     

Microstructure of industrially manufactured goat cheese Queso de Murcia al Vino during synaeresis

The microstructural parameters of an industrially manufactured goat cheese curd (pore number, area and perimeter, strand thickness and porosity) were analysed by scanning electron microscopy and image analysis during synaeresis. The water‐holding capacity, whey fat, pH and moisture content were also determined to establish any relationship with the curd microstructure. The quantification of the different microstructural parameters made it possible to assign pitching and stirring as important processing steps because these steps impart different features to the curd microstructure. Higher pore number was related to reduced pore area, perimeter and strand thickness, but higher porosity and moisture.     

The Tribology of PS212 Coatings and PM212 Composites for the Lubrication of Titanium 6A1-4V Components of a Stirling Engine Space Power System

The Stirling space power machine incorporates a linear alternator to generate electrical power. The alternator is a reciprocating device that is driven by a solar or nuclear-powered Stirling engine. The power piston and cylinder are made of titanium 6A1–4V (Ti6–4) alloy, and are designed to be lubricated by a hydrodynamically-generated gas film. Rubbing occurs during starts and stops and there is the possibility of an occasional high speed rub. Since titanium is known to have a severe galling tendency in sliding contacts, a “backup,” self-lubricating coating on the cylinder and/or the piston is needed. This report describes the results of a research program to study the lubrication of Ti6–4 with the following chromium carbide based materials: plasma-sprayed PS212 coatings and sintered PM212 counterfaces. Program objectives are to achieve adherent coatings on Ti6–4 and to measure the friction and wear characteristics of the following sliding combinations under conditions simulative of the Stirling-driven space power linear alternator: Ti6–4/Ti6–4 baseline, Ti6–4/PS212-coated Ti6–4, and PS212-coated Ti6–4/PM212.     

Neutral beam deployment on DEMO and its influence on design

The demands on the neutral beam heating and current drive system of a DEMO device exceed those of existing fusion experiments by several orders of magnitude. By predicting possible power waveforms it is possible to analyse the technological advances necessary to achieve a system relevant to deployment on a power plant. Achieving the necessary efficiency will require simultaneous improvements in beam current density, neutralization efficiency and beam transmission. Considering the deployment on the tokamak vessel shows no major disruption to the tritium breeder blanket and no requirement to reach a high packing density of injectors. The thermal management of components subjected to low heat flux for many hours is considered and it is shown that radiation cooling can be exploited to control the temperature of such items.     

Friction stir welding of aluminium casting alloys

The results of testing friction stir welding quality in relation to EN AC-43200 (AK9) and EN AC-45000 (AK64) aluminium casting alloys are presented. The test joints were made with the use of a welding machine constructed on the basis of numerically controlled milling machines. The assessment of the joint quality was made based on visual inspection, mechanical testing, weldment structure analysis and hardness tests. The purpose of the investigation was to discover the possibility of friction stir welding of casting alloys and the influence of welding conditions on joint properties and structure. The test results show good weldability of aluminium casting alloys by the FSW method. Sound welds can be obtained in a relatively wide range of welding parameters while the weld strength is satisfactory. In order to obtain the highest quality joints, the workpieces must be pressed onto the other, while the welding process cannot run with excessively high speed. The best mechanical properties of the joints were achieved when the friction process was conducted at a rotational speed of the mixing tool of 900 rpm.     

Comparison of mode-resolved fracture strength of silicon with mixed-mode failure of diamond crystals

Currently ab initio theory provides the ideal tensile and shear strength of the {111} cleavage plane in single-crystal silicon and diamond only for few selected planes and directions (‘geometries’). These values can be compared with the real strength of nano-, micro-, and single-crystalline devices to roughly judge their mechanical quality. A novel contact-free and notch-free optical laser method allows the measurement of the fracture strength with plane nonlinear surface acoustic waves (SAWs), providing a unique way to discriminate between tensile and shear stresses for well-defined crystallographic planes and directions in anisotropic materials. Calibration yields the critical fracture stress or strength for the geometries, which can be compared with theory. In the case of diamond mostly mechanistically unresolved mixed-mode failure has been studied for complex geometries. Nevertheless, the comparison of these critical failure stresses with the strength of the ideal lattice and the mode- and geometry-resolved fracture behavior of silicon provides new insight into the mechanical stability and failure behavior of diamond materials.     

Isogeometric analysis of the isothermal Navier–Stokes–Korteweg equations

This paper is devoted to the numerical simulation of the Navier–Stokes–Korteweg equations, a phase-field model for water/water-vapor two-phase flows. We develop a numerical formulation based on isogeometric analysis that permits straightforward treatment of the higher-order partial–differential operator that represents capillarity. We introduce a new refinement methodology that desensitizes the numerical solution to the computational mesh and achieves mesh invariant solutions. Finally, we present several numerical examples in two and three dimensions that illustrate the effectiveness and robustness of our approach.     

Broadband Ge/SiGe quantum dot photodetector on pseudosubstrate

We report the fabrication and characterization of a ten-period Ge quantum dot photodetector grown on SiGe pseudosubstrate. The detector exhibits tunable photoresponse in both 3- to 5- μm and 8- to 12- μm spectral regions with responsivity values up to about 1 mA/W at a bias of −3 V and operates under normal incidence radiation with background limited performance at 100 K. The relative response in the mid- and long-wave atmospheric windows could be controlled through the applied voltage.