Formation and Geometry of a High-Coverage Oxygen Adlayer on Ru(001), the p(2 × 2)-3O Phase

A detailed low-energy electron diffraction (LEED)-IV analysis, complemented by scanning tunneling microscopy (STM) observations, was carried out for the apparent (2 × 2) structure of the oxygen-covered Ru(001) surface at a coverage of 0.75 ML. We present STM images of incomplete layers which allow one to define the symmetry of the ordered layer, in particular of the novel high density p(2 × 2)-3O phase. In the LEED-IV analysis we have tested 28 model structures; the results can be used for conclusions about the discrimination of this type of geometry determination. Our quantitative LEED analysis in connection with the STM results corroborates the model proposed before and shows that all of the oxygen atoms sit in the hcp sites with an averaged vertical distance to the outermost Ru layer of d^⊥_Ru–O = 1.22 Å. This value falls into the general trend of increasing d^⊥_Ru–O with oxygen coverage observed for the other ordered structures of adsorbed oxygen on Ru and is also predicted by recent total energy calculations. The O–Ru bonding distance of about 2.0 Å is essentially unchanged compared to the other structures. Considerable lateral and vertical displacements of both the O and the Ru atoms are found, with the O atoms being slightly displaced towards the fcc hollow site located in the center of three oxygen atoms. The two uppermost substrate layers are buckled; in the first layer three out of four Ru atoms of the (2 × 2) unit cell are shifted away laterally from their bulk positions. These shifts, globally as well as locally, can be understood in terms of local electron density changes induced by the adsorbed oxygen atoms.     

Potential Health Risks Associated with Particles in Reclaimed Wastewater

Human dose-response data from seven pathogens commonly associated with waterborne illness were used in conjunction with acceptable levels of risk specified by the United States EPA to determine an allowable particle limit for reclaimed water assuming varying degrees of pathogen association. Assuming particles contain a single pathogen, particle limits ranged from 213,000 particles/L for E. coli ETEC to 400 particles/billion L for rotavirus. Particle concentrations in the effluent from nine reclamation facilities that employed advanced filtration exceeded calculated allowable particle limits for one or more pathogens despite achieving permitted water quality standards. Hence, current methods of estimating particle densities (e.g., turbidity and suspended solids) and indicator organisms are potentially incongruent with acceptable levels of risk specified by the United States EPA. The significance of this incongruence is dependent on the uncertain frequency of pathogen association with wastewater particles.     

Nonsymmetric Deformation Behavior of Lead Zirconate Titanate Determined in Bending Tests

Soft lead zirconate titanate (PZT) ceramics exhibit a nonsymmetric deformation behavior, where the tensile strains exceed the compressive strains for a given stress level. This phenomenon affects the strains in bending tests. In addition to the normally determined bending strain that is measured by the curvature of a specimen, an additional length extension occurs that can be used as a high-sensitive indicator for the occurrence of the nonsymmetric behavior. Furthermore, it will be shown that the pure tensile and compression behavior may be derived from bending tests.     

Ginzburg–Landau Analysis of the Doll–Näbauer Experiment

The Doll–Näbaucr experiment is reconsidered with respect to its theoretical interpretation in terms of the Ginzburg–Landau theory. We find analytical results for the temperature and magnetic field dependence of the order parameter, the transition temperature in finite fields, and the magnetic flux trapped inside the cylinder. This work is intended to demonstrate once again the predictive power and the conceptual beauty of the Ginzburg–Landau theory and is devoted to Vitalij Ginzburg on the occasion of his 90th birthday.     

Steady state flow of cohesive and non-cohesive powders

Steady state flow of powders is a crucial concept to investigate the powders’ strength and flow properties. This state is defined as a continuous deformation of the material without volume change while the stresses at the specimen’s boundaries remain constant. Recent investigations have shown that this state, especially for cohesive powders, is not always as constant as it should be by definition. This paper presents experimental and numerical work, both for cohesive and non-cohesive powders. The experimental part focuses on the use of different control strategies, leading to steady state flow of different quality. Differences between steady state flow for cohesive and non-cohesive powders are shown.     

Open source software-defined radio tools for education,research, and rapid prototyping

Software-defined radios (SDR) offer several advantages over traditional, hardware-based radios, most notably flexibility and reconfigurability. Developing SDR applications can be a difficult process, however, for several reasons. First, much of the work involved deals with standards compliance, rather than radio functionality. This portion of the work is very detailed and error prone, leading to wasted time and effort. Second, there is little to no support available for the debugging and refinement portions of the development cycle. There is no easy way to monitor or control SDR applications at runtime. The Waveform Workshop was created to address these issues. A part of the OSSIE SDR project, the Waveform Workshop drastically reduces the time and effort involved in SDR development. It automatically generates the portions of the software related to standards compliance, letting developers concentrate on radio functionality. In addition, the Waveform Workshop provides tools for both monitoring and controlling SDR applications at runtime, making debugging much easier.     

Evaluation of the operationally defined soluble, insoluble, and complexing copper consumed through drinking water in human saliva

Previous studies suggest that different copper species formed in saliva have different reactivity in chemical reactions that may be associated with perception of metallic sensation occurring in the oral cavity. This study was performed to understand copper speciation in human saliva, which will help to understand the perception mechanism of metallic taste. Saliva samples were treated with CuSO₄·5H₂O at the levels of 0, 2.5, 10, 20, or 40 mg/L as Cu in vitro. Also saliva is collected before and after drinking 20 mL of 0, 2.5, and 5 mg/L copper in water (in vivo treatment). Copper speciation was operationally determined based on apparent molecular size using ultrafiltration coupled with inductively coupled plasma mass spectrometry. For in vitro copper treatment, 50–70% of copper was soluble at Cu ≤ 10 mg/L, whereas 60–70% of copper was in complex or insoluble form at Cu > 20 mg/L. For in vivo copper treatment, 90–95% of copper was soluble in saliva. These results suggest that copper is in the soluble unbound form in saliva at low concentrations. At higher concentrations, copper either becomes insoluble or binds with salivary components.     

Why Redox Pulping Catalysts Pit the Square Root Relationship

Different mixture rates of the redox pulping additives anthraquinone with anthraquinone-2-sulfonate, and of benzindazoledione with rosindonesulfonate were investigated. The experimental results showed that additives in mixtures very strongly influence each other's efficacy. The degree of coupling indicates that the square root relationship is best explained by kinetics of the chemical reaction mechanism and not by mass transfer processes.