Atomic Ordering and Martensitic Transitions in Cu-Zn-Al Shape Memory Alloys

We present results from both, calorimetric and dilatometric studies of the isothermal ordering process taking place in a Cu-Zn-Al shape memory alloy after quenches from Tq temperatures ranging from 350 K to 1200 K. The dissipated energy and the length variations of the system are obtained during the process. The change of these quantities in the whole process have been compared with the difference [MATH] between Ms, measured after the relaxation and Ms measured just after the quench. We obtain that these three quantities present, as a function of Tq, the same qualitative behaviour. These changes are then associated with changes of the L21 ordering after the quench in the system. The relaxational process does not follow a single exponential decay. Instead, a continuous slowing down is observed. A relaxation time [MATH] has been defined to characterize the relaxation rate. We show that [MATH] depends on both the annealing and the quenching (Tq [MATH] 800 K) temperatures through an Arrhenius law.

Hepatitis G virus infection in primary Sjögren's syndrome: analysis in a series of 100 patients.

OBJECTIVE To determine the prevalence and clinical significance of hepatitis G virus (HGV) infection in a large cohort of patients with primary Sjögren¿s syndrome (SS). PATIENTS AND METHODS The study included 100 consecutive patients (92 female and eight male), with a mean age of 62 years (range 31¿80) that were prospectively visited in our unit. All patients fulfilled the European Community criteria for SS and underwent a complete history, physical examination, as well as biochemical and immunological evaluation for liver disease. Two hundred volunteer blood donors were also studied. The presence of HGV-RNA was investigated in the serum of all patients and donors. Aditionally, HBsAg and antibodies to hepatitis C virus were determined. RESULTS Four patients (4%) and six volunteer blood donors (3%) presented HGV-RNA sequences in serum. HGV infection was associated with biochemical signs of liver involvement in two (50%) patients. When compared with primary SS patients without HGV infection, no significant differences were found in terms of clinical or immunological features. HCV coinfection occurs in one (25%) of the four patients with HGV infection. CONCLUSION The prevalence of HGV infection in patients with primary SS is low in the geographical area of the study and HCV coinfection is very uncommon. HGV infection alone does not seen to be an important cause of chronic liver injury in the patients with primary SS in this area.

100 casos de derecho de daños (2004-2009)

InDret presenta, por sexto año consecutivo, una selección de veinte sentencias sobre responsabilidad civil dictadas por el Tribunal Supremo que tratan cuestiones centrales del derecho de daños. El lector también encontrará en este trabajo las selecciones de 2004, 2005, 2006, 2007 y 2008 publicadas en números anteriores.

Disponibilitat per a les plantes de Mn, Cu, Zn i Cd en els sòls de diferents sistemes agrícoles a Catalunya

Es va avaluar el contingut del sòl en Mn, Cu, Zn, Ni i Cd fent una extracció amb DTPA, segons el mètode de Lindsay i Norvell (1969). Les mostres analitzades procedien de parcel·les agrícoles d'arreu de Catalunya, conservades al Banc de Mostres de Sòls del Mapa de Sòls de Catalunya del DARP. Els resultats es van agrupar per sistemes agrícoles en funció de l'origen de les mostres, ja que dins de cada un es pot assumir una reducció important en l'interval de variació de diferents factors. Es va realitzar una comparació estadística entre els valors mitjans dels diferents sistemes agrícoles, entre els valors mitjans de les dues profunditats de sòl considerades, i una interpretació agronòmica. Els resultats van indicar que els sòls procedents d'horticultura intensiva del Maresme són els que tenen continguts disponibles més elevats dels metalls considerats. D'altra banda, es fa palès que els valors estan condicionats tant pel material originari del sòl com per l'acció antròpica. Per al Cu i el Zn en les mostres de sòls del Maresme els continguts trobats estan molt per sobre dels mínims considerats com a agronòmicament satisfactoris.

Mineralización estratiforme de Pb-Zn-Cu en el Paleozoico de Bassegoda (Pirineo Oriental)

Al Sur del pico de Bassegoda existe una mineralización estratiforme de galena, esfalerita y pirita con calcopirita y arsenopirita, en forma de diseminaciones y lentejones masivos, situadas dentro de un tramo de 10 metros de micaesquistos y dolomias negras. Estos niveles mineralizados se hallan en el contacto entre micaesquistos y dolomias masivas que contienen piroclastos cidos. Tanto el tipo de depósito como la litologia encajante, permiten correlacionar esta mineralización con un conjunto de concentraciones metalicas estratiformes y estratoligadas del Cambro-Ordovicico del NE de Cataluña.

Geology of the Cerro-Quema Au-Cu deposit (Azuero Peninsula, Panama)

The Cerro Quema district, located on the Azuero Peninsula, Panama, is part of a large regional hydrothermal system controlled by regional faults striking broadly E-W, developed within the Río Quema Formation. This formation is composed of volcanic, sedimentary and volcano-sedimentary rocks indicating a submarine depositional environment, corresponding to the fore-arc basin of a Cretaceous-Paleogene volcanic arc. The structures observed in the area and their tectono-stratigraphic relationship with the surrounding formations suggest a compressive and/or transpressive tectonic regime, at least during Late Cretaceous-Oligocene times. The igneous rocks of the Río Quema Formation plot within the calc-alkaline field with trace and rare earth element (REE) patterns of volcanic arc affinity. This volcanic arc developed on the Caribbean large igneous province during subduction of the Farallon Plate. Mineralization consists of disseminations of pyrite and enargite as well as a stockwork of pyrite and barite with minor sphalerite, galena and chalcopyrite, hosted by a subaqueous dacitic lava dome of the Río Quema Formation. Gold is present as submicroscopic grains and associated with pyrite as invisible gold. A hydrothermal alteration pattern with a core of advanced argillic alteration (vuggy silica with alunite, dickite, pyrite and enargite) and an outer zone of argillic alteration (kaolinite, smectite and illite) has been observed. Supergene oxidation overprinted the hydrothermal alteration resulting in a thick cap of residual silica and iron oxides. The ore minerals, the alteration pattern and the tectono-volcanic environment of Cerro Quema are consistent with a high sulfidation epithermal system developed in the Azuero peninsula during pre-Oligocene times.

Hardness of FRHC-Cu determined by statistical analysis

A statistical indentation method has been employed to study the hardness value of fire-refined high conductivity copper, using nanoindentation technique. The Joslin and Oliver approach was used with the aim to separate the hardness (H) influence of copper matrix, from that of inclusions and grain boundaries. This approach relies on a large array of imprints (around 400 indentations), performed at 150 nm of indentation depth. A statistical study using a cumulative distribution function fit and Gaussian simulated distributions, exhibits that H for each phase can be extracted when the indentation depth is much lower than the size of the secondary phases. It is found that the thermal treatment produces a hardness increase, due to the partly re-dissolution of the inclusions (mainly Pb and Sn) in the matrix.

Magnetic properties of an Fe/Cu granular multilayer

A Cu/Fe granular film, formed from a multilayer film and composed of particles of Fe imbedded in Cu, has had several of its important properties investigated. Measurements include ferromagentic resonance, magnetoresistance, Mössbauer effect, magnetic viscosity, and magnetization. The two‐phase behavior of these immiscible alloy systems, and the effect of multilayering on the shape of the magnetic precipitates, can explain some of these properties. An explanation of the ferromagnetic resonance line shape is proffered. An extraordinary macroscopic quantum tunneling effect is found to govern the magnetic relaxation at the lowest temperatures.

Adsorption energy and spin state of first-row transition metals adsorbed on MgO(100)

Slab and cluster model spin-polarized calculations have been carried out to study various properties of isolated first-row transition metal atoms adsorbed on the anionic sites of the regular MgO(100) surface. The calculated adsorption energies follow the trend of the metal cohesive energies, indicating that the changes in the metal-support and metal-metal interactions along the series are dominated by atomic properties. In all cases, except for Ni at the generalized gradient approximation level, the number of unpaired electron is maintained as in the isolated metal atom. The energy required to change the atomic state from high to low spin has been computed using the PW91 and B3LYP density-functional-theory-based methods. PW91 fails to predict the proper ground state of V and Ni, but the results for the isolated and adsorbed atom are consistent within the method. B3LYP properly predicts the ground state of all first-row transition atom the high- to low-spin transition considered is comparable to experiment. In all cases, the interaction with the surface results in a reduced high- to low-spin transition energy.

Contribución al conocimiento de la geología del depósito de Au-Cu de La Pava (Península de Azuero, Panamá)

The «La Pava» Au-Cu deposit is hosted by a vulcanosedimentary sequence, named Ocú Formation,developed in an island arc environment that resulted from the subduction of the Nazca Plate beneath the Caribbean Plate during the Cretaceous times. The deposit consists of disseminations and stockworks of pyrite and chalcopyrite accompanied by barite, quartz and carbonates. Three hydrothermal alteration zones have been recognized: silicic, argillic and propilityc, typical of gold-related high sulfidation systems. A supergenic alteration overprints the hydrothermal alterations developing a cap rich in silica and Feoxides. The detailed study of the Ocú Fm. indicates that the sulfides and the accompanying gold was formed in a submarine environment. Therefore we suggest that «La Pava» represents an Au-Cu hybrid deposit between high sulphidation epithermal and VMS types, which are found in volcanogenic massive sulphide environments.

Isotype distribution of anticardiolipin antibodies in systemic lupus erythematosus prospective analysis of a series of 100 patients

A prospective study of IgG and IgM isotypes of anticardiolipin antibodies (aCL) in a series of 100 patients with systemic lupus erythematosus was carried out. To determine the normal range of both isotype titres a group of 100 normal control serum samples was studied and a log-normal distribution of IgG and IgM isotypes was found. The IgG anticardiolipin antibody serum was regarded as positive if a binding index greater than 2.85 (SD 3.77) was detected and a binding index greater than 4.07 (3.90) was defined as positive for IgM anticardiolipin antibody. Twenty four patients were positive for IgG aCL, 20 for IgM aCL, and 36 for IgG or IgM aCL, or both. IgG aCL were found to have a significant association with thrombosis and thrombocytopenia, and IgM aCL with haemolytic anaemia and neutropenia. Specificity and predictive value for these clinical manifestations increased at moderate and high anticardiolipin antibody titres. In addition, a significant association was found between aCL and the presence of lupus anticoagulant. Identification of these differences in the anticardiolipin antibody isotype associations may improve the clinical usefulness of these tests, and this study confirms the good specificity and predictive value of the anticardiolipin antibody titre for these clinical manifestations.