Real-world quantum sensors: evaluating resources for precision measurement

Quantum phenomena present in many experiments signify nonclassical behavior, but do not always imply superior performance. Quantifying the enhancement achieved from quantum behavior needs careful analysis of the resources involved. We analyze the case of parameter estimation using an optical interferometer, where increased precision can in principle be achieved using quantum probe states. Common performance measures are examined and some are shown to overestimate the improvement. For the simplest experimental case we compare the different measures and exhibit this overestimation explicitly. We give the preferred analysis of these experiments and calculate benchmark values for experimental parameters necessary to realize a precision enhancement. Our analysis shows that unambiguous real-world enhancements in optical quantum metrology with fixed photon number are yet to be attained.     

Hydraulic fracturing with a simplified fluid model and XFEM

In hydraulic fracturing, the pressure exerted by the fracking fluid onto the surrounding solid, is typically obtained from solving the Reynolds equation. This is not always robust and leads to a complex behaviour at the crack front (toughness or viscous regimes). In the presented work, the Reynolds equation is replaced by a simplified fluid model, where pre-defined pressure distributions are assumed which lead to a simpler and robust coupled problem. The surface integration of the fluid pressure onto the surrounding solid is outlined without any limitations on the distributions. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Surface structure and roughness of Nickel-Titanium wires

Nickel-Titanium wires not only show the well known shape memory effect, but also pseudoelastic behaviour. This means, as the material is bent in a wide range of tension, the stress in the material stays constant. This special behaviour allows the improvement of orthodontic devices. The investigation of wires for this application reveals great differences in the surface roughness of the wires from various suppliers. The roughness causes a loss of spring energy for the orthodontic wire by frictional effects. The investigation of the mechanical behaviour of these materials leeds to differences compared with the ideal behaviour expected for the stress/strain curve. Obviously these differences are caused by surface effects of the wires. To evaluate these questions intensive roughness measurements with profilometry, laser spectroscopy and scanning force microscopy have been performed. Further more defined bending and tensile experiments have been carried out and corresponding roughness and structure analysis with the scanning force microscope has been taken into account. By etching the wires significant surface effects could be found.     

Plasma polymerized p-xylene as a laser fusion target 1

Various polymers have been found to be quite useful for laser fusion target applications. There is often a need for a film with low atomic number and superior strength to accommodate a variety of free-standing configurations with a minimum thickness. The particular film characterized in this study is plasma-polymerized p-xylene. The depositions were made with an ac glow discharge between parallel plate electrodes. Uniform coatings on spherical substrates were deposited by keeping the spheres in motion in the plasma with an electromechanical vibrating table. The films with the greatest strength were found to be grown from gas phase mixtures of argon and p-xylene and the deposition rate and the character of the film were examined as a function of argon concentration. Studies were made of oxygen absorption by the film (as determined by infrared spectroscopy) and powder formation on the surface (as seen by SEM). Further problems unique to laser target fabrication will also be discussed.     

Near UV-visible light induced cationic photopolymerization reactions: A three component photoinitiating system based on acridinedione/silane/iodonium salt

Acridinediones (AD) are attractive dyes exhibiting a strong absorption at about 400 nm. When used in the presence of a silane and an iodonium salt, they efficiently initiate the free radical promoted cationic photopolymerization of an epoxide under air and upon a xenon lamp, a laser diode or sunlight exposure. The mechanism analyzed by ESR and laser flash photolysis is discussed and opens a new way for the design of such three-component systems.     

Simplified enrichment and identification of environmental peptide toxins using antibody-capture surfaces with subsequent mass spectrometry detection

The development of a simplified assay for detection of congeners of the microcystin (MC) hepatotoxin is described that combines the extreme sensitivity of surface-enhanced laser desorption/ionization time-of-flight MS (SELDI TOF-MS) with the superior selectivity of immunoaffinity interactions. Using methods similar to those of conventional immunoassays, MC standards were captured and enriched on immunoreactive ProteinChips coated with an MC-antibody and analyzed by TOF-MS. Unlike with conventional immunoassays, individual congeners were resolved from mixed pools. Assay conditions were optimized for the quantification of MC from untreated raw pond water at concentrations as low as 0.025 microg L(-1), well below the public health relevant guideline of 1 microg L(-1).