Catalytic conversion of methane to methanol on Cu-SSZ-13 using N2O as oxidant.

Direct catalytic methanol production from methane is achieved on Cu-SSZ-13 zeolite catalysts using N2O as the oxidant. The methanol production rate on Cu-SSZ-13 (on a per gram basis) was more than twice the rate on Cu-mordenite and more than four times the rate on Cu-ZSM-5.

Conversion of methane to methanol on copper-containing small-pore zeolites and zeotypes.

This communication reports the discovery of several small-pore Cu-zeolites and zeotypes that produce methanol from methane and water vapor, and produce more methanol per copper atom than Cu-ZSM-5 and Cu-mordenite. The new materials include Cu-SSZ-13, Cu-SSZ-16, Cu-SSZ-39, and Cu-SAPO-34.

Molecular beam-thermal hydrogen desorption from palladium.

Among the most efficient techniques for hydrogen desorption monitoring, thermal desorption mass spectrometry is a very sensitive one, but in certain cases can give rise to uptake misleading results due to residual hydrogen partial pressure background variations. In this work one develops a novel thermal desorption variant based on the effusive molecular beam technique that represents a significant improvement in the accurate determination of hydrogen mass absorbed on a solid sample. The enhancement in the signal-to-noise ratio for trace hydrogen is on the order of 20%, and no previous calibration with a chemical standard is required. The kinetic information obtained from the hydrogen desorption mass spectra (at a constant heating rate of 1 degrees C/min) accounts for the consistency of the technique.

Evidence for orbital-specific electron transfer to oriented haloform molecules.

Beams of hyperthermal K atoms cross beams of the oriented haloforms CF(3)H, CCl(3)H, and CBr(3)H, and transfer of an electron mainly produces K(+) and the X(-) halide ion which are detected in coincidence. As expected, the steric asymmetry of CCl(3)H and CBr(3)H is very small and the halogen end is more reactive. However, even though there are three potentially reactive centers on each molecule, the F(-) ion yield in CF(3)H is strongly dependent on orientation. At energies close to the threshold for ion-pair formation ( approximately 5.5 eV), H-end attack is more reactive to form F(-). As the energy is increased, the more productive end switches, and F-end attack dominates the reactivity. In CF(3)H near threshold the electron is apparently transferred to the sigma(CH) antibonding orbital, and small signals are observed from electrons and CF(3)(-) ions, indicating "activation" of this orbital. In CCl(3)H and CBr(3)H the steric asymmetry is very small, and signals from free electrons and CX(3)(-) ions are barely detectable, indicating that the sigma(CH) antibonding orbital is not activated. The electron is apparently transferred to the sigma(CX) orbital which is believed to be the LUMO. At very low energies the proximity of the incipient ions probably determines whether salt molecules or ions are formed.

SSZ-26 and SSZ-33: Two Molecular Sieves with Intersecting 10- and 12-Ring Pores.

The framework structures of two closely related molecular sieves, SSZ-26 and SSZ-33, are described. These materials possess a previously missing but desired structural feature in a group of industrially significant zeolites. They contain a three-dimensional pore system that provides access to the crystal interior through both 10- and 12-rings. This property is a consequence of the organic structure-directing agents used in the synthesis of these materials. These materials are examples of the purposeful design of a micropore architecture. Both SSZ-26 and SSZ-33 contain the 4=4-1 building unit that had been previously found only in natural zeolites.

Inelastic response of reinforced concrete structures with viscoelastic braces

The adition of viscoelastic braces in structures for vibration reduction was proposed and implemented in the past decade in metal models or full-scale structures. Viscoelastic braces provide energy dissipation, while the structures remains by-and-large elastic. In reinforced concrete structures, the seismic response in by-and-large inelastic, which is often accompanied by permanent deformations and damage. The addition of viscoelastic dampers can dissipate energy at the early stages of cracking of the concrete elemnts and reduce the development of damage. With proper selectio of dampers, this damage can be substantially reduced or even eliminated. However the addition of viscoelastic dampers may stiffen the structure unnecessarily producing increased inertial forces and base shears when subjected to seismic motion. The quantification of the influence of viscous and elastic stiffness properties of dampers during the inelastic response of reinforced concrete structures is the subject of this invetigation. Models for analysis of inelastic response with damege indexing for reinforced concrete structures that include viscoelastic braces are developed and calibrated using experimental data produced by shaking table tests. These models are then used to determine the variation of expected damage in the presence of damping and quantify the hysteretic energy dissipation along with the damping energy (AU)

The objective clinical assessment of the quality of the anterior segment by means of the Oqual.

The Oqual is a simple new device attachable to the (Haag-Streit or Topcon) slit-lamp. It provides objective numerical assessments of the optical quality of the anterior segment. In the present study, patients attending Outpatients Clinics at Moorfields Eye Hospital were divided into those who suffered from lenticular symptoms and those who did not. Their monocular visual acuity was measured routinely by means of a Snellen chart, and thereafter their eyes were examined with the Oqual. Results are given for the correlation between the two measures overall (R2 = 47.35%), and for inter-observer performance (r = 0.8878). Earlier conclusions on the effects of smoking habits are supported.

IDARC version 3.0 : A program for the inelastic damage analysis of reinforced concrete structures

This report summarizes the significant modeling and program enhancements to the computer coe, IDARC (see Technical Report NCEER-87-0008) for inelastic damage analysis of reinforced concrete frame-wall structures. The base program is capable of analyzing structures in the inelastic range subjected to combined horizontal and vertical excitations, quasi-static cyclic loading, and incrementally applied static loads.(AU)