Basis set limit electronic excitation energies, ionization potentials, and electron affinities for the 3d transition metal atoms: Coupled cluster and multireference methods

Recently developed correlation consistent basis sets for the first row transition metal elements Sc-Zn have been utilized to determine complete basis set (CBS) scalar relativistic electron affinities, ionization potentials, and 4s(2)3d(n-2)-4s(1)d(n-1) electronic excitation energies with single reference coupled cluster methods [CCSD(T), CCSDT, and CCSDTQ] and multireference configuration interaction with three reference spaces: 3d4s, 3d4s4p, and 3d4s4p3d'. The theoretical values calculated with the highest order coupled cluster techniques at the CBS limit, including extrapolations to full configuration interaction, are well within 1 kcal/mol of the corresponding experimental data. For the early transition metal elements (Sc-Mn) the internally contracted multireference averaged coupled pair functional method yielded excellent agreement with experiment; however, the atomic properties for the late transition metals (Mn-Zn) proved to be much more difficult to describe with this level of theory, even with the largest reference function of the present work.     

Synthesis of loliolide, actinidiolide, dihydroactinidiolide, and aeginetolide via cerium enolate chemistry

Loliolide, aeginetolide, actinidiolide, and dihydroactinidiolide were synthesized in racemic form from a single common intermediate, prepared through the 1,2 addition of the cerium enolate of ethyl acetate to 2,6,6-trimethylcylohexenone.     

High Frequency PMN-PT 1-3 Composite Transducer for Ultrasonic Imaging Application

Development of PMN-PT single crystal/epoxy 1-3 composites for high-frequency ultrasonic transducers application is presented. The composite was fabricated by using a DRIE dry etching process with a 45% volume fraction of PMN-PT. A 35 MHz ultrasound flat transducer was fabricated with the composite, which was found to have an effective electromechanical coupling coefficient of 0.81, an insertion loss of 18 db, and a -6 dB bandwidth as high as 100%. Tungsten wire phantom image shows that the transducer had an axial resolution of 30 μm, which was in good agreement with the theoretical expectation. The initial results showed that the PMN-PT/epoxy 1-3 composite has many attractive properties over conventional piezoelectric materials for medical imaging applications.     

On the affordances of the MaxEP principle

Optimality principles have long been popular in the natural sciences and enjoyed much successes in various applications. However these principles seem to be disparate, each applied in limited contexts and there are far too many of them causing some consternation among scientists and philosophers of science regarding the ad-hoc nature of the optimality arguments. In this paper, we discuss the Maximum entropy production (MaxEP) as a plausible over-arching principle to understand stable configurations in fluid mechanics and related problems. The MaxEP being based upon sound physical arguments and in the immutable laws of thermodynamics along with the fact that it has been successfully co-opted across disciplines makes it worthy of attention. We discuss various physical and metaphysical aspects of this principle and use it to analyze some model problems regarding patterns in particle sedimentation such as sedimentation of a particle in Newtonian and non-Newtonian fluids and stable deformation of a falling droplet.     

Shear localisation in stirred yoghurt

The shear flow behaviour of stirred yoghurt in the cone-and-plate and cylindrical Couette geometries was studied using diffusing wave spectroscopy (DWS) and nuclear magnetic resonance (NMR) velocimetry. Differences between the transmission and backscattering DWS correlations suggest the formation of a high shear rate band near the surface of a moving cone of a cone-and-plate geometry at low shear rates. At higher shear rates, homogeneous shear flow is indicated. NMR velocimetry unambiguously demonstrated that a high shear rate band forms at the moving inner wall of a cylindrical Couette geometry at low shear rates. At intermediate shear rate, a high shear rate band is formed at the stationary outer wall and plug-like flow is observed mid-gap. At higher shear rates, homogeneous shear flow is observed. Slip is seen at both walls. The three flow regimes appear to correlate loosely with transitions in the pseudo-steady-state flow curve and may reflect a break-up of the protein aggregates observed with confocal microscopy.     

Fixed points of asymptotic contractions

Let be a contractive gauge function in the sense that φ is continuous, φ(s)<s for s>0, and if f:M→M satisfies d(f(x),f(y))?φ(d(x,y)) for all x,y in a complete metric space (M,d), then f always has a unique fixed point. It is proved that if T:M→M satisfies

     

A Web-Based Molecular-Level Inquiry Laboratory Activity

This paper presents a new computer-based atomic level simulation of an ideal gas. The simulation is written in Java and is accessed by students through a Web browser. This software is used in conjunction with a written laboratory experiment developed within the framework of an inquiry instructional strategy. This molecular-level laboratory experiment is used in combination with a parallel macroscopic laboratory experiment. We hypothesize that students exposed to these kinds of parallel activities will be better able to link the macroscopic, microscopic, and symbolic understanding of chemical concepts.Presented at the ACS Division of Chemical Education sponsored symposium on web-assisted learning in chemistry at its 221st national meeting in San Diego, CA April 1–5, 2001.