Minimum detection efficiency for a loophole-free atom-photon bell experiment

In Bell experiments, one problem is to achieve high enough photodetection to ensure that there is no possibility of describing the results via a local hidden-variable model. Using the Clauser-Horne inequality and a two-photon nonmaximally entangled state, a photodetection efficiency higher than 0.67 is necessary. Here we discuss atom-photon Bell experiments. We show that, assuming perfect detection efficiency of the atom, it is possible to perform a loophole-free atom-photon Bell experiment whenever the photodetection efficiency exceeds 0.50.     

Supralinearity in nuclear research emulsions

Nuclear emulsions processed in discriminating developers, intended to suppress small latent image sites, exhibit supralinear sensitometric blackness-exposure curves, whose character varies according to developing time, concentration, and composition, yielding hittedness ranging from 1 to 8, singly and in combination. These emulsion-processing combinations display the phenomena called ion-kill (sensitization by the transit of a single charged particle) and gamma- kill (sensitization by the overlap of secondary electron paths, whether from x-rays or from the delta-rays of heavy ions) in radiobiology. Here emulsions are blackened by x-rays when these same plates reveal no electron tracks, or no alpha-particle tracks, or even no fission fragment tracks. The supralinearity of the emulsion response to x-rays, and the consequent suppression of low LET radiations suggest that these materials have the potential to mimic the response of biological systems to particulate radiations of different charge and speed.     

Effects of feedback from collimating, focusing, and spot-array generating outcoupler gratings in surface-emitting semiconductor lasers

We experimentally demonstrate that a grating outcoupler used for complex beam shaping (spot-array generation) can produce unintentional optical feedback that severely disturbs the integrated in-plane laser that illuminates the coupler. Simulations show that these outcouplers, in contrast to conventional collimating or focusing outcouplers, tend to produce high levels of feedback in spite of the detuning used to suppress feedback. Further, this feedback is focused to high intensity in the laser gain medium. This focused light acts as a seed for the nonlinear self-focusing that causes wave-front distortion and filamentation, which degrades the beam quality.     

PHYSICAL STRUCTURE AND PHASE PROPERTIES OF AQUEOUS SYSTEMS OF LIPIDS FROM RYE AND TRITICALE IN RELATION TO WHEAT LIPIDS

In connection with studies of technical functionality of lipids in cereals, the aqueous systems of lipids from rye and tri-ticale flour are described and compared to different wheat culti-vars. Rye lipids give a lamellar liquid-crystalline phase with very small ordered regions, and this phase is continuously changed into an L2-phase with increasing water content. Triticale lipids exhibit phase equilibria in between lipids of wheat and of rye. Evidence is given for a significant role of the lamellar liquid--crystalline phase with regard to technical functionality when the cereal flour is worked in water to give a dough.     

Gas permeation of fullerene‐dispersed poly(1‐trimethylsilyl‐1‐propyne) membranes

Homogeneously fullerene‐dispersed membranes were prepared under the conditions in which a 10 wt % poly(1‐trimethylsilyl‐1‐propyne) solution containing 0.5 wt % fullerene was dried under a reduced pressure of 50 cmHg at 100 °C. UV‐vis spectra and microscopic observations of the fullerene membranes indicated that the fullerene was homogeneously dispersed in the membranes. The permeability coefficients of 1‐butene were found to be higher than those of n‐butane in the fullerene membranes, although the permeability coefficients of olefin gases were nearly equal to those of paraffin gases having the same number of carbon in poly(1‐trimethylsilyl‐1‐propyne) membranes containing no fullerene. Pressure dependence of permeability coefficients was clearly observed for the permeation of carbon dioxide, ethylene, ethane, 1‐butene, and n‐butane through the fullerene membranes, while no significant dependence was found for poly(1‐trimethylsilyl‐1‐propyne) membranes except for the permeation of 1‐butene and n‐butane. The pressure dependence of the permeability was explained by the dual‐mode sorption model. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1749–1755, 2000     

Solid‐state drawing of β‐nucleated polypropylene: Effect of additives on drawability and mechanical properties

Isotactic polypropylene (i‐PP) can crystallize in different crystal modifications. In this article, the effect of sepiolite (one‐dimensional) and carbon black (three‐dimensional) fillers on the solid‐state drawability of i‐PP is discussed. The cross‐hatched structure of thermodynamically most stable α‐crystal phase in i‐PP does not allow for perfect chain alignment during solid‐state drawing. The β‐phase i‐PP, obtained by addition of specific nucleating agents, crystallizes in a non‐cross‐hatched spherulitic structure and allows more easy drawing. Depending on the filler type, β–α transformation takes place at different draw ratios, as was observed by in situ wide‐angle X‐ray diffraction measurements. It was observed that β‐nucleated i‐PP has a lower yield stress and can be drawn further than i‐PP crystallized in the α‐crystal phase. If added in the right amount, both carbon black and sepiolite have a reinforcing effect on PP tapes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1071–1082     

Anharmonic vibrational spectroscopy calculations with electronic structure potentials: comparison of MP2 and DFT for organic molecules

Density functional theory (DFT) technique is the most commonly used approach when it comes to computation of vibrational spectra of molecular species. In this study, we compare anharmonic spectra of several organic molecules such as allene, propyne, glycine, and imidazole, computed from ab initio MP2 potentials and DFT potentials based on commonly used BLYP and B3LYP functionals. Anharmonic spectra are obtained using the direct vibrational self-consistent field (VSCF) method and its correlation-corrected extension (CC-VSCF). The results of computations are compared with available experimental data. It is shown that the most accurate vibrational frequencies are obtained with the MP2 method, followed by the DFT/B3LYP method, while DFT/BLYP results are often unsatisfactory. Contribution to the Mark S. Gordon 65th Birthday Festschrift Issue.     

Crystallographic analysis of metal-ion binding to human ubiquitin

The metal-binding ability of human ubiquitin (hUb) towards a selection of biologically relevant metal ions and complexes has been probed. Different techniques have been used to obtain crystals suitable for crystallographic analysis. In the first type of experiments, crystals of hUb have been soaked in solutions containing copper(II) acetate and two metallodrugs, Zeise salt (K[PtCl(3)(η(2)-C(2)H(4))]·H(2)O) and cisplatin (cis-[PtCl(2)(NH(3))(2)]). The Zeise salt is used in a test for hepatitis, whereas cisplatin is one of the most powerful anticancer drugs in clinical use. The Zeise salt readily reacts with hUb crystals to afford an adduct with three platinum residues per protein molecule, Pt(3)-hUb. In contrast, copper(II) acetate and cisplatin were found to be unreactive for contact times up to one hour and to cause degradation of the hUb crystals for longer times. In the second type of experiments, hUb was cocrystallized with a solution of copper(II) or zinc(II) acetate or cisplatin. Zinc(II) acetate gives, at low metal-to-protein molar ratios (8:1), crystals containing one metal ion per three molecules of protein, Zn-hUb(3) (already reported in previous work), whereas at high metal-to-protein ratios (70:1) gives crystals containing three Zn(II) ions per protein molecule, Zn(3)-hUb. In contrast, once again, copper(II) acetate and cisplatin, even at low metal-to-protein ratios, do not give crystalline material. In the soaking experiment, the Zeise anion leads to simultaneous platination of His68, Met1, and Lys6. Present and previous results of cocrystallization experiments performed with Zn(II) and other Group 12 metal ions allow a comprehensive understanding of the metal-ion binding properties of hUb with His68 as the main anchoring site, followed by Met1 and carboxylic groups of Glu16, Glu18, Glu64, Asp21, and Asp32, to be reached. In the case of platinum, Lys6 can also be a binding site. The amount of bound metal ion, with respect to that of the protein, appears to be a relevant parameter influencing crystal packing.     

Gas transport in TiO2 nanoparticle-filled poly(1-trimethylsilyl-1-propyne)

Titanium dioxide (TiO₂) nanoparticles were dispersed via solution processing in poly(1-trimethylsilyl-1-propyne) (PTMSP) to form nanocomposite films. Nanoparticle dispersion was investigated using atomic force microscopy and transmission electron microscopy. At low-particle loadings, nanoparticles were dispersed individually and in nanoscale aggregates. At high-particle loadings, some nanoparticles formed micron-sized aggregates. The gas transport and density exhibited a strong dependence on nanoparticle loading. At low-TiO₂ loadings, the composite density was similar to or slightly higher than that predicted by a two-phase additive model. However, at particle loadings exceeding approximately 7 nominal vol.%, the density was markedly lower than predicted, suggesting that the particles induced the creation of void space within the nanocomposite. For example, when the TiO₂ nominal volume fraction was 0.35, the polymer/particle composite density was 40% lower than expected based on a two-phase additive model for density. At low-nanoparticle loading, light gas permeability was lower than that of the unfilled polymer. At higher nanoparticle loadings, light gas permeability (i.e., CO₂, N₂, and CH₄) increased to more than four times higher than in unfilled PTMSP. At most, selectivity changed only slightly with particle loading.