Model oxide-supported metal catalysts--comparison of ultrahigh vacuum and solution based preparation of Pd nanoparticles on a single-crystalline oxide substrate

Using single-crystalline Fe(3)O(4)(111) films grown over Pt(111) in UHV as a model-support, we have characterized the nucleation behaviour and chemical properties of Pd particles grown over the film using different deposition techniques with scanning tunnelling microscopy and X-ray photoelectron spectroscopy. Comparison of Pd/Fe(3)O(4) samples created via Pd evaporation under UHV conditions and those resulting from the solution deposition of Pd-hydroxo complexes reveals that changes in the interfacial functionalization of such samples (i.e. roughening and hydroxylation) govern the differences in Pd nucleation behavior observed over pristine oxides relative to those exposed to alkaline solutions. Furthermore, it appears that other differences in the nature of the Pd precursor state (i.e. gas-phase Pd in UHV vs. [Pd(OH)(2)](n) aqueous complexes) play a negligible role in Pd nucleation and growth behaviour at elevated temperatures in UHV, suggesting facile decomposition of the Pd complexes deposited from the liquid phase. Applying temperature programmed desorption and infrared spectroscopy to probe the CO chemisorption properties of such samples after reduction in different reagents (CO, H(2)) shows the formation of bimetallic PdFe alloys following reduction in H(2), but monometallic Pd particles after CO reduction.     

Diastereoselective formation of seven-membered oxacycles by ring-expansion of cyclopropanated galactal

The cyclopropanation and ring-expansion of 4,6-O-di-(tert-butyl)silanediyl-d-galactal using catalytic amounts of TMSOTf and silated nucleophiles gave a range of substituted oxepanes. Good to excellent yields were obtained in addition to very high selectivities.     

A Directory of Coefficients of Tail Dependence

Models characterizing the asymptotic dependence structures of bivariate distributions have been introduced by Ledford and Tawn (1996), among others, and diagnostics for such dependence behavior are presented in Coles et al. (1999). The following pages are intended as a supplement to the papers of Ledford and Tawn and Coles et al. In particular we focus on the coefficient of tail dependence, which we evaluate for a wide range of bivariate distributions. We find that for many commonly employed bivariate distributions there is little flexibility in the range of limiting dependence structure accommodated. Many distributions studied have coefficients of tail dependence corresponding to near independence or a strong form of dependence known as asymptotic dependence.     

Infrared spectra of high coverage CO adsorption structures on Pt(111)

The adsorption of carbon monoxide on Pt(111) was studied using polarization modulation infrared reflection absorption spectroscopy (PM-IRAS) and sum frequency generation (SFG) spectroscopy. Two CO on-top signals at 2110 cm^? 1 and 2097 cm^? 1 have been detected under continuous CO exposure in a pressure range from 10^? 7 to 100 mbar and at temperatures between 200 K and 300 K. The formation of the higher wavenumber signal is found to be kinetically limited below 200 K and by the presence of a stable c(4 × 2) adlayer in UHV. On the basis of the results presented in this study and previous experimental findings the two on-top signals are related to different CO compression layers on Pt(111) with θ > 0.5, hexagonal Moiré lattices and rectangular coincident site lattices.     

Observation of a near-threshold D(0)D[over](0)pi(0) enhancement in B-->D(0)D[over](0)pi(0)Kappa decay

We report the first observation of a near-threshold enhancement in the D(0)D[over](0)pi(0) system from B-->D(0)D[over](0)pi(0)Kappa decays using a 414 fb(-1) data sample collected at the Upsilon(4S) resonance. The enhancement peaks at a mass M=3875.2+/-0.7(+0.3)/(-1.6) +/-0.8 MeV/c2 and the branching fraction for events in the peak is B(B-->D(0)D[over](0)pi(0)Kappa)=(1.22+/-0.31(+0.23)/(-0.30))x10(-4). The data were collected with the Belle detector at the KEKB energy-asymmetric e+ e- collider.     

Observation of new states decaying into Lambda(c)(+)Kappa(-)pi(+) and Lambda(c)(+)Kappa(0)/(s)pi(-)

We report the first observation of two charmed strange baryons that decay into Lambda(c)(+)Kappa(-)pi(+). The broader of the two states is measured to have a mass of 2978.5+/-2.1+/-2.0 MeV/c2 and a width of 43.5+/-7.5+/-7.0 MeV/c2. The mass and width of the narrow state are measured to be 3076.7+/-0.9+/-0.5 MeV/c;{2} and 6.2+/-1.2+/-0.8 MeV/c2, respectively. We also perform a search for the isospin partner states that decay into Lambda(c)(+)Kappa(0)/(s)pi(-) and observe a significant signal at the mass of 3082.8+/-1.8+/-1.5 MeV/c2. The data used for this analysis were accumulated at or near the Upsilon(4S) resonance, using the Belle detector at the e+ e- asymmetric-energy collider KEKB. The integrated luminosity of the data sample used is 461.5 fb(-1).     

Transferring specialized content knowledge to elementary classrooms: preservice teachers’ learning to teach the associative property

This study explores how preservice teachers (PSTs) transfer the intended specialized content knowledge (SCK) to elementary classrooms. Focusing on the case of the associative property of multiplication, we compared three PSTs’ SCK during enacted lessons in fourth grade classrooms with their own learning in professional development (PD) settings. Findings revealed the PSTs’ successes and challenges in unpacking an example task, especially in areas of making connections between concrete and abstract representations and asking deep questions that target quantitative interactions. Factors that may have supported or hindered PSTs’ SCK transfer include the complex nature of teacher knowledge, the PD effort and the outside factors such as the support from textbooks and cooperating teachers. Implications for teacher education and directions for future research are discussed.     

Extreme Value Analysis of a Large Designed Experiment: A Case Study in Bulk Carrier Safety

The bulk carrier M.V. Derbyshire sank in 1980 when she encountered a typhoon near Japan. The most likely cause of her loss was finally explained in the report of the Re-opened Formal Investigation in 2000. The report also revealed inadequacies in safety standards for such vessels, particularly concerning regulations governing hatch cover strengths, and requested further work be undertaken to examine the sufficiency of aspects of the existing international standards for ship design. This paper describes the extreme value analysis of data from a large designed experiment intended to aid the revision of these safety standards. We highlight the importance of consistency of results over the different conditions examined, and how this can be achieved using various data pooling and regression techniques.     

Further remarks on partitioning the edges of a graph

The main result is that if m and k are odd integers with m ≥ k ≥ 1, then any graph which is the union of m graphs of maximum valence k is also the union of k graphs of maximum valence m. This is not generally true if k > m.