Search for scalar top and scalar bottom quarks in pp collisions at square root s=1.8 TeV

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb-1 of pp collisions at sqrt[s]=1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.     

Plasmon modes of curvilinear metallic core/shell particles

The plasmon hybridization method is generalized to calculate the plasmon modes and optical properties of solid and dielectric-core/metallic-shell particles of geometrical structures that can be described using separable curvilinear coordinates. The authors present a detailed discussion of the plasmonic properties of hollow metallic nanowires with dielectric cores and core/shell structures of oblate and prolate spheroidal shapes. They show that the plasmon frequencies of these particles can be expressed in a common form and that the plasmon modes of the core/shell structures can be viewed as resulting from the hybridization of the solid particle plasmons associated with the outer surface of the shell and of the cavity plasmons associated with the inner surface.     

Asymmetric catalysis LVI. Enantioselective hydrosilylation of acetophenone with a rhodium/picolineoxazoline catalyst 1:1

The direction of optical induction is inverted in going from pyridineoxazoline 1 to picolineoxazoline 2 as cocatalyst in the Rh-catalyzed asymmetric hydrosilylation of acetophenone with diphenylsilane. In the case of ligand 2, a 1.2-fold excess of the ligand is sufficient to achieve the highest enantiomeric excess.     

Integrated optical receiver for indoor wireless gigabit communication

A receiver with a monolithically integrated PIN photodiode in 0.5 μm BiCMOS technology has been developed for establishing an indoor 1.25 Gb/s optical wireless communication over a distance of 3.2 m using 180 μW of optical power.     

Pressure effects in a plastic columnar discotic triphenylene

The effect of hydrostatic pressure on the structure of a plastic columnar discotic triphenylene has been investigated. The goal was to determine whether pressure can be used to modify electronic properties via changes in structural properties of columnar discotics to any significant extent. The findings are that (i) the intra‐ and inter‐columnar distances are reduced in a nearly isotropic fashion, (ii) that the crystal sizes are reduced and (iii) that a transition takes place from a more highly ordered plastic columnar to a less ordered hexagonal columnar state with increasing pressure. The induced decrease of the molecular distances, amounting to 6% for pressures up to 17?kbar, are clearly too small to induce an appreciable modification of the electronic structure and thus opto‐electronic properties.     

Evaluating efficacy of environmental education programming

The Clark Fork Watershed Education Program (CFWEP) goals are: (a) increasing students’ understanding of the nature of ecological impacts within their watershed as related to historic mining damage; and (b) increasing students’ sense of stewardship of newly restored landscapes. Data from 2012 to 2016 were evaluated for student knowledge gains (46 trials representing 2,395 student pre‐surveys; 2,409 student post‐surveys). Data from 2013 to 2016 were evaluated for students’ attitudes toward science and disposition toward caring for the environment (38 trials representing 1,479 pre‐surveys; 1,460 post‐surveys). The results of this study support that the program’s goals are being achieved. Students achieved statistically significant gains on knowledge surveys with a 33.4% overall gain pre‐ to posttest (p < 0.0001). Students also moved toward greater positive responses in both attitudes toward science and disposition toward caring for the environment with Cohen’s d effect sizes of “medium effect” for caring toward the environment (d = 0.52) and “small effect” of positive disposition toward science (d = 0.24).     

Propagation Kinetics of Isoprene Radical Homopolymerization Derived from Pulsed Laser Initiated Polymerizations

The propagation kinetics of isoprene radical polymerizations in bulk and in solution are investigated via pulsed laser initiated polymerizations and subsequent polymer analyses via size‐exclusion chromatography, the PLP‐SEC method. Because of low polymerization rate and high volatility of isoprene, the polymerizations are carried out at elevated pressure ranging from 134 to 1320 bar. The temperatures are varied between 55 and 105 °C. PLP‐SEC yields activation parameters of k_p (Arrhenius parameters and activation volume) over a wide temperature and pressure range that allow for the calculation of k_p at technically relevant ambient pressure conditions. The k_p values determined are very low, e.g., 99 L mol^?1 s^?1 at 50 °C, which is even lower than the corresponding value for styrene polymerizations. The presence of a polar solvent results in a slight increase of k_p compared to the bulk system. The k_p values reported are important for determining rate coefficients of other elemental reactions from coupled parameters as well as for modeling isoprene free‐radical polymerizations and reversible deactivation radical polymerization with respect to tailored polymer properties and optimizing the polymerization processes.     

A method to correct defocused element distribution maps in electron probe microanalysis

Element distribution maps obtained on electron microprobes via the beam scan method with wavelength-dispersive spectrometers reveal a defocusing effect if they are taken at sufficiently small magnification. This effect, which occurs where the Bragg condition of the spectrometer is not adequately met, can be avoided or corrected by various methods. A method is presented here to correct defocused element distribution maps with the help of corresponding maps obtained on homogeneous standards.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

Study of interactions in Co–SiO2 granular films by means of MFM and magnetization measurements

A study of Co[SiO₂] granular films using magnetic force microscopy (MFM), transmission electron microscopy and DC magnetization is presented. MFM shows large strip magnetic domains in the percolated system and allows a more direct investigation of the magnetic interaction among grains in the film with the lowest metal volume fraction.