Search results for "COMPOSITION"

Identification of passive layers on Co in Alkaline solutions by photocurrent spectroscopy

2005

The photoelectrochemical behavior of passive films on Co has been studied as a function of the polarizing voltage and electrolyte composition. Passive layers formed at 0 V (standard hydrogen electrode, SHE) in 0.1 M NaOH consisted of Co(OH) 2 , whose bandgap value has been found to be 1.85 eV. Higher bandgap values (2.75 eV) have been measured for passive films formed in borate buffer at 0 V (SHE), which are mainly consist of CoO. The Eg values have been related to the film composition on the basis of a correlation between the bandgap of passive films and the electronegativity of their constituents.

Complementary methods assessing short and long-term prey of a marine top predator ‒ Application to the grey seal-fishery conflict in the Baltic Sea.

2019

The growing grey seal (Halichoerus grypus) population in the Baltic Sea has created conflicts with local fisheries, comparable to similar emerging problems worldwide. Adequate information on the foraging habits is a requirement for responsible management of the seal population. We investigated the applicability of available dietary assessment methods by comparing morphological analysis and DNA metabarcoding of gut contents (short-term diet; n = 129/125 seals, respectively), and tissue chemical markers i.e. fatty acid (FA) profiles of blubber and stable isotopes (SIs) of liver and muscle (mid- or long-term diet; n = 108 seals for the FA and SI markers). The methods provided complementary inf…

Solid-State Synthesis of “Bamboo-Like” and Straight Carbon Nanotubes by Thermolysis of Hexa-peri-hexabenzocoronene–Cobalt Complexes

2006

Bounce Rock-A shergottite-like basalt encountered at Meridiani Planum, Mars

2011

Additional co-authors: Thanasis ECONOMOU, Steven P. GOREVAN, Brian C. HAHN, Gostar KLINGELHOFER, Timothy J. McCOY, Harry Y. McSWEEN Jr, Douglas W. MING, Richard V. MORRIS, Daniel S. RODIONOV, Steven W. SQUYRES, Heinrich WANKE, Shawn P. WRIGHT, Michael B. WYATT, Albert S. YEN

Raw material variability as archaeological tools: Preliminary results from a geochemical study of the basalt vessel workshop at Iron Age Tel Hazor, I…

2016

The discovery of a basalt vessel workshop at Tel Hazor, one of the most important Iron Age sites in the Near East, marks a turning point in our understanding of stone artifact production and distribution during the1st millennium BCE. It offers a rare opportunity to characterize ancient raw material sources, production sites, and study production, trade and distribution systems. The basalt vessel workshop, the only one of its kind in the Levant, produced large quantities of bowl preforms and production waste. To better understand the production and distribution systems behind this specialized production center, in 2011 we initiated a focused geochemical project that concentrated on the produ…

The Spirit Rover's Athena science investigation at Gusev Crater, Mars.

2004

The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.

Theoretical study of stationary structures of acetamidine unimolecular decomposition

1990

Abstract The unimolecular decomposition of acetamidine to ammonia and acetonitrile was examined by ab initio methods. Stationary points, i.e. the reactant, product and transition structures, have been characterized. The process has an asynchronous mechanism, the transition state being described as a four-membered ring. To establish the relevance of different basis sets, calculations with eight standard Gaussian basis sets, STO-3G, 3-21G, 4-21G, 4-31G, 6-31G, 6-311G, 6-31G*, and G-31G**, were carried out.

High-frequency modification of the central Mediterranean seafloor environment over the last 74 ka

2022

Here we present a high-resolution record of benthic foraminiferal assemblages for the last 74 kyr from the Sicily Channel Ocean Drilling Program Leg 160 Site 963. Benthic foraminiferal results are compared with geochemical (benthic and planktic δ18O and δ13C) and calcareous plankton data, previously acquired on the same marine core sediments. Within the succession, three benthic foraminifera compositional zones were defined. Temporal changes in the assemblages are interpreted in the context of the modification of subtropical and temperate climate systems that affected the Mediterranean thermohaline circulation. A close connection between bottom conditions in the Sicily Channel and eastern M…

Application of the 3-D boundary element method to delaminated composite structures

2013

A three-dimensional boundary element model for anisotropic solids is presented to study the fracture mechanics behavior of delaminated composite structures. The multi-domain technique is implemented to model the layered configurations and the cracks occurring at bi-material interface. The Modified Crack Closure Integral technique is implemented to characterize the fracture mechanics behavior of delaminations in terms of the total energy release rate and mode mix phase angles. Validating analyses, performed on different delaminated configurations, have shown the effectiveness of the proposed approach. Moreover, some original results are presented to investigate the effects of the stacking se…

Arynic species; effect of substituents on the reactivity of monosubstituted dehydrobenzenes

1986

Abstract Evidence is presented demonstrating the existence of free dehydrobenzenes in the thermal decomposition of diaryliodonium-2-carboxylates, and that o-benzyne itself and its 4-methyl-, 4-chloro-,4-bromo- and 4-nitro-derivatives are generated from insoluble polymer-bound precursors and trapped by a second solid phase in Diels-Alder reactions. Lifetimes for these elusive species are determined.