Morphologies and electro-optic properties of polystyrene/liquid crystal composite films

Morphology and electro-optic properties of composite films composed of polystyrene (PS) and nematic liquid crystal (LC) have been studied for a wide range (30-70 wt% of liquid crystal) of film composition. At two specific levels of LC loadings (50 and 60 wt%), effects of temperature, frequency and voltage of applied ac electric field on the transmittance of the films were intensively measured, and the results were interpreted in terms of aggregation structure of the film, the geometry of LC domains, LC loading, dielectric constant, conductivity, birefringence, and the solubility of LC in polymer. © 1994 John Wiley & Sons, Inc.     

Determination of the angular and energy dependence of hard constituent scattering from π0 pair events at the CERN intersecting storage rings

We present data on proton-proton collisions, obtained at the CERN Intersecting Storage Rings, in which two roughly back-to-back π⁰'s of high transverse momentum (p_T) were produced. The angular distribution of the dipion axis relative to the collision axis is found to be independent of both the effective mass m of the dipion system and the centre-of-mass energy √s of the proton-proton collision. The cross-sections $\text{d}\text{σ}\text{d}\text{m}$ at the values of √s satisfy a scaling law of the form $\text{d}\text{σ}\text{d}\text{m}\text{=}\text{G(x)}\text{m}{}^{\mathrm{n}}\text{,}\text{where}\text{x = m(π}{}^0\text{, π}{}^0\text{)//trs}\text{and}\text{n = 6.5 ± 0.5}$. We show from our data that the leading π⁰ carries most of the momentum of the scattered parton. Given this fact, the axis of the dipion system follows closely the direction of the scattered constituents, and we exploit this to determine the angular dependence of the hard-scattering subprocess. We also compare our data with the lowest order QCD predictions using structure functions as determined in deep-inelastic scattering and fragmentation functions from electron-positron annihilation.     

Operational features and microwave characteristics of the VircatorII experiment

The Vircator II oscillating virtual-cathode microwave source operates with diode voltages between 600 and 800 kV and diode current between 50 and 120 kA. Maximal microwave output power between 200 and 500 MW is achieved when the diode aspect ratio, cathode surface, charge voltage, and extraction coupling are arranged to simultaneously (1) maximize diode voltage, (2) satisfy magnetic insulation criteria, (3) avoid nonuniform or unstable electron emission, and (4) optimize microwave transmission from the virtual cathode to the launching antenna. Broadband radiation between 0.4 and 5.5 GHz is generated. The central frequency follows the beam plasma frequency. It is tuned by varying the current density with anode-cathode gap adjustments     

XPS studies of carbon supported films formed by the resistive deposition of manganese

The surface and subsurface speciation of carbon-supported vapor-deposited films, prepared by resistively heating manganese chips in the sample chamber of an HP 5950A ESCA spectrometer, have been studied using XPS and argon ion etching. It is shown that the oxide formed in poor vacuum is MnO. Under improved experimental conditions, a mixture of Mn metal and MnO is obtained, but the metal is very reactive to oxygen. For very thick films formed in poor vacuum, the oxide covers a layer of manganese metal. The oxide is no longer evident after 60 h of etching. For the layer of manganese remaining, we have found that the Mn3s multiplet splitting is smaller than that reported in the literature. The present result is shown to be consistent with magnetic susceptibility measurements on α-Mn. For discontinuous MnO films, argon ion etching causes the Mn2p binding energy to shift to higher energy. This is inconsistent with reduction to Mn metal, as the binding energy would shift to a lower value for this case.     

Infrared regularization of the massless scalar free field in two-dimensional space-time via Lorentz expansion

It is shown that Lorentz harmonics provide a natural basis for the expansion and infrared regularization of a massless scalar field in two dimensions. The negative metric operators separate out simply. Each Lorentz component of the field is partially local.     

The electronic properties of [CH(FeCl4)0.061]x

The temperature dependence of d.c. conductivity, thermopower and electron paramagnetic resonance (EPR) results on [CH(FeCl₄)_0.061]_x are reported. The d.c. conductivity and thermopower measurements indicate metallic charge transport along the polyacetylene chain interrupted by the interfibril contact resistances and also ‘dragged’ primarily by the dopant ions. The initial measurements of EPR show Dysonian lineshape with very broad linewidth (ΔH ≈ 600 G at room temperature). The temperature dependence of EPR absorption intensity implies that there exist localized magnetic moments. The observed g value (g ≈ 2.03) suggests the dopant anion is in a form of (FeCl₄)^-.     

L2 multipliers with power weights

Necessary and sufficient conditions are found for a multiplier operator to be bounded on L² of the line with weight |x|^2α. This paper is concerned primarily with the case $\text{α>}\text{1}\text{2}$. Multiplier operators are defined on these spaces by using the usual definition on a subspace that is shown to be dense in the space. The case $\text{α < ?}\text{1}\text{2}$ is treated by duality; $\text{|α| <}\text{1}\text{2}$ is briefly treated using a recent result on fractional integrals. The periodic case is also sketched.     

Charge asymmetry and neutron-neutron scattering

The uncertainty in the subtraction of electromagnetic effects from S-wave proton-proton scattering potentials is studied in two models using unitarily transformed potentials. Restrictions on these models caused by theoretical, off-shell and deuteron constraints are imposed. The probable uncertainty of physical interest is found to be small. It is typically only a few parts per thousand of the one-pion exchange potential. It has relatively little effect on Coulomb displacement energies. Phenomenological charge-symmetry-breaking potentials are constructed which both fit the experimental neutron-neutron (nn) scattering length (?16.4 fm). and give roughly the needed Coulomb displacement energies. These phenomenological potentials are found to contain a short-range repulsion and a strong long-range attraction for a neutron pair. The need for experimental information on the shape and state dependence of the nn force is emphasized. These can probably be obtained from precise nn scattering measurements.     

Oscillatory behavior during the oxygen oxidation of ascorbic acid

The oscillatory phenomenon was observed in aqueous solution during the oxidation of ascorbic acid by oxygen. Even though the exact number and amplitude of the oscillations could not be exactly duplicated for each and every run, such factors as temperature, concentration of ascorbic acid, cupric ions, and pH affecting the oscillatory behavior were studied, and those regions where oscillations occurred were delineated. A mechanism consistent with the oscillatory behavior is proposed and discussed.     

On the molecular structure and nmr spectrum of cis-[PtPh2(Ph2PCH2PPh2)]

The X-ray crystal structure analysis of cis-[PtPh₂(Ph₂PCH₂PPh₂)] suggests that the unusually low PtP coupling constant is a consequence of distortion of the valency angles at the platinum and phosphorus atoms; the restrictive geometry of the chelate ring does not effect the lengths of the metal—ligand bonds.