In this study, the oxidation kinetics of low-carbon, low-silicon steel in flowing air at 850–1,180 掳C within 30 or 60 s were examined. The parabolic kinetics were established from the very early stage at 850掳 and 1,000 掳C, whereas the oxidation kinetics at 1,100–1,180 掳C appeared to obey a linear law initially and a more-parabolic one at a later stage. When the oxidation kinetics followed the linear law, “rough”-scale with an undulating, saw-teeth like microstructure developed, whereas when the parabolic law was followed, smooth scale developed. It appeared that a critical scale thickness existed, at which the scale-growth mechanism changed from linear to parabolic. This thickness was less than 7 μm at 850 掳C, about 10 μm at 1,000 掳C, about 50 μm at 1,100 掳C and in the range of 60–80 μm at 1,180 掳C under the conditions examined. Blister formation at 900 掳C prevented clear observation of the linear-to-parabolic transition.
脡tant donn茅s deux points x et y d'une vari茅t茅 riemannienne compacte M de dimension d≥2 et un mouvement brownien X issu de x, on prouve qu'il existe un mouvement brownien issue de y, qui rencontre presque s没rement X et qui engendre la m锚me filtration. Avec une d茅monstration analogue 脿 celle de l'expos茅 pr茅c茅dent, on en d茅duit que la filtration naturelle du mouvement brownien index茅 par ℝ et 脿 valeurs dans M est 脿 un changement de temps r茅gulier pr猫s, 茅gale 谩 la filtration naturelle d'un mouvement brownien index茅 par ℝ+, 脿 valeurs dans ℝd et issu de 0.
The C鈥揔 theory is a recent theory of reasoning in design. Despite many practical applications, the theory has not yet been operationalized in the form of a computational design tool. In this paper, we argue that, in order to build such tools, a third space鈥攁n environment space E鈥攎ust be introduced to the theory. Therefore, we extend the C鈥揔 design theory, using ideas and principles from situated cognition. As we discuss, the new version provides a theoretical background for building personal design assistants鈥攃reative and adaptive design tools. [ABSTRACT FROM AUTHOR]
It is shown that deuteration of C60 fullerite followed by thermal decomposition of the resulting deuteride C60D24 leads to the formation of an fcc lattice with a 0=14.52 Å in the final product, which according to the IR spectra consists mainly of C60 fullerene molecules.
Ivano Bertini
Isabella C. Felli
Leonardo Gonnelli
Roberta Pierattelli
Zinovia Spyranti and Georgios A. Spyroulias
The copper-mediated protein–protein interaction between yeast Atx1 and Ccc2 has been examined by protonless heteronuclear NMR and compared with the already available 1H–15N HSQC information. The observed chemical shift variations are analyzed with respect to the actual solution structure, available through intermolecular NOEs. The advantage of using the CON-IPAP spectrum with respect to the 1H–15N HSQC resides in the increased number of signals observed, including those of prolines. CBCACO-IPAP experiments allow us to focus on the interaction region and on side-chain carbonyls, while a newly designed CEN-IPAP experiment on side-chains of lysines. An attempt is made to rationalize the chemical shift variations on the basis of the structural data involving the interface between the proteins and the nearby regions. It is here proposed that protonless 13C direct-detection NMR is a useful complement to 1H based NMR spectroscopy for monitoring protein–protein and protein–ligand interactions.
At the appropriate times, silica diffusion in clay is possibly the rate determining process for the dissolution of vitrified waste disposed of in a clay layer. For testing this hypothesis, combined glass dissolution/silica diffusion experiment are performed. SON68 glass coupons doped with the radioactive tracer 32Si are sandwiched between two cores of humid Boom Clay, heated to 30 掳C. Due to glass dissolution, 32Si is released and diffuses into the clay. At the end of an experiment, the mass loss of the glass coupon is measured and the clay core is sliced to determine the diffusion profile of the 32Si released from the glass in the clay.Both mass loss and the 32Si diffusion profile in the clay are described well by a model combining glass dissolution according to a linear rate law with silica diffusion in the clay. Fitting the experiments to this model leads to an apparent silica diffusion coefficient in the clay between 7 脳 10鈭?3 m2/s and 1.2 脳 10鈭?2 m2/s. Previously determined values from diffusion experiments at 25 掳C are around 6 脳 10鈭?3 m2/s (In-Diffusion experiments) and 2 脳 10鈭?3 m2/s (percolation experiments). The maximal glass dissolution rate for glass next to clay is around 1.6 脳 10鈭? g glass/m2 s (i.e. 0.014 g glass/m2 day). In undisturbed clay, the measured silica concentration is around 5 mg/L. Combining these values with the previously measured (In-Diffusion experiments) product of accessible porosity and retardation factor, leads in two ways to a silica glass saturation concentration in clay between 8 and 10 mg Si/L.Another candidate for the rate determining process of the dissolution of vitrified waste disposed in a clay layer is silica precipitation. Although silica precipitation due to glass dissolution has been shown experimentally at 90 掳C, extending the model with silica precipitation does not lead to much better fits, nor could meaningful values of a possible precipitation rate be obtained.
During the nineteenth century, the existence of a southern border in the C贸rdoba province resulted from a complex situation where an expanding national state was inserted into a global economic system and into an environment occupied by various Indian groups. This situation created a mixed society on the borderlands. The military line was defended by forts, with one of them being the Achiras Fort (1832–1869). The fort was situated at the end of the mountain range of Comechingones. This paper considers the archaeological investigation of this fort. The most important and consistent part of the archaeological record is the Command. The Command was formed by two rooms. This work also presents the results of the excavations into the fort and describes the archaeological remains found. Finally, a general model for archaeology in the South C贸rdoba Border is presented.
The effects of compressive stresses on the oxide-scale morphologies formed on an Fe–20Cr alloy were investigated by comparison of the oxidation behavior in air under classical conditions, i.e., without any applied mechanical stresses and under static compressive stresses, at 900 掳C. The study was carried out mainly by comparisons of oxidation kinetics gained by thermogravimetric analysis (TGA), surface morphologies of oxidized specimens observed by scanning electron microscopy (SEM), oxidized products examined by X-ray diffraction (XRD). It was found that the application of compressive stresses induced an increase in oxidation rate, but a decrease of oxide grain size. When the stresses are in the range of 5–8 MPa, both chromium- and iron-oxides formed but, at other stresses, only chromia was present. In particular, there was a maximum in oxidation rate when the applied stress was 5 MPa. The paper places emphasis on analyzing the cause of this phenomenon.
System-level understanding of living organisms has been a long-standing goal of biological sciences. However, it was only recently that this possibility became concrete, by virtue of the development of technology platforms for the production of “omics” data from multiple experimental sources. Data sets such as those from genomics and proteomics are endowing researchers with an unprecedented view of the molecular constituents of cells and of their interactions, forming the basis to pursue the comprehension of how the concerted action of such components can determine biological functions. Within this challenge, bioinorganic chemistry is invested with a renewed significance, being called to place its distinctive subject matter, namely, the study of the interactions between inorganic and biological molecules, in a system-wide perspective. The first step to take in this direction is the construction of “omics” data sets for metalloproteins (metalloproteomics) that can be fruitfully integrated with other protein-centered “omics” data. While looking forward to the progress of high-throughput experimental techniques to accomplish this task, theoretical methods are yielding valuable predictions as to the number of metalloproteins encoded in various genomes. The integrated use of these and others “omics” data can be extremely useful to model complex cellular processes involving metals. Here, we review the current knowledge on copper homeostasis and the assembly of cytochrome c oxidase to exemplify the kind of important processes which need to be studied at the system level. The long-term goal of this approach is the overall description of how metals are framed as essential factors within living cells, which in fact is the ultimate purpose of bioinorganic chemistry.