Mineralogical Characterization of Dolomitic Aggregate Concrete: The Camarasa Dam (Catalonia, Spain)

The Camarasa Dam was built in 1920 using dolomitic aggregate and Portland cement with two di erent compositions: type A (dolomite and Portland cement) and type B (dolomite and sand-cement). The sand cement was a finely powdered mixture of dolomite particles and clinker of Portland cement. The mineralogy of concrete was studied by optical microscopy, scanning electron microscopy, and x-ray powder di raction. Reaction of dedolomitization occurred in the two types of concrete of the Camarasa Dam, as demonstrated by the occurrence of calcite, brucite, and/or absence of portlandite. In the type A concrete, calcite, brucite, and a serpentine-group mineral precipitated as a rim around the dolomite grains and in the paste. The rims, a product of the dedolomitization reaction, protected the surface of dolomite from the dissolution process. In type B concrete, in addition to dolomite and calcite, quartz and K-feldspar were present. Brucite occurred in lower amounts than in the type A concrete as fibrous crystals randomly distributed in the sand-cement paste. Although brucite content was higher in the type A concrete, type B showed more signs of loss of durability. This can be attributed to the further development of the alkali-silica reaction in this concrete type

MINROCIND una eina d'aprenentatge presencial e interactiva dels jaciments de roques i minerals industrials a Catalunya. Eina d'aprenentatge presencial i/o interactiu en el àmbit dels ensenyaments de la mineralogia i petrologia aplicada

Es tracta d'un material i eina didàctica a la vegada. Té doncs una doble vesant: a) una part física constituïda per una mostra de roca polida i una làmina prima de la mateixa roca, per a ser utilitzada a l'hora de pràctiques a classe; i b) una part virtual formada per una base de dades interactiva on els estudiants trobaran fitxes amb les característiques bàsiques de la roca, i la descripció de les pedreres més importants on es troben i la seva importància com a recurs econòmic, com a roca ornamental i/o industrial

Mineralogical and thermal characterization of borate minerals from Rio Grande deposit, Uyuni (Bolivia)

Large volumes of borate resources exist in Bolivia, with the most important being the Rio Grande deposit, located close to the Salar of Uyuni. Here, borates occur in beds and lenses of variable thickness. A mineralogical and thermal characterization of borates from the Rio Grande was made using XRD, FTIR, SEM and DTA TG. The deposit is mainly composed of B2O3, CaO and Na2O, with minor contents of MgO and K2O. Some outcrops are constituted by pure ulexite aggregates (NaCaB5 O6(OH)6 5H2O) of fibrous morphology; in other cases, gypsum, calcite and halite also are present. The thermal decomposition of ulexite begins at 70 C and proceeds up to *550 C; this decomposition is attributed to dehydration and dehydroxylation processes in three steps: at 115, 150 300 and 300 550 C. The last mass loss of 1 5 % at 800 C is due to the removal of Cl2 from the decomposition of halite. DTA shows two endothermic events related to the removal of water; in the first, NaCaB5O6(OH)6 5H2O evolved from NaCaB5O6(OH)6 3H2O, at 108 116 C; in the second, NaCaB5O6(OH)6 is formed at 180 185 C and NaCaB5O9 (amorphous) is formed at 300 550 C. The exothermic peak (658 720 C) is related to the crystallization of NaCaB5O9. A small endothermic peak appears due to the halite melting. Later, another endothermic event (821 877 C) appears, which is related to the decomposition of NaCaB5O9 into a crystalline phase of CaB2O4 and amorphous NaB3O5. The XRD pattern evidences that, at 1050 C, CaB2O4 still remains in the crystalline state

Avances en el diagnóstico y tratamiento de las arritmias cardíacas

The era of catheter ablation for the treatment of arrhythmias began in 1981 when Dr Scheinman performed the first atrioventricular junction ablation using direct current shocks in a patient with drug refractory atrial fibrillation and an uncontrolled ventricular rate. With the progress of radiofrequency catheter ablation, the range of arrhythmias amenable to catheter ablation and the number of patients that could be treated safely by this procedure expanded enormously. Lastly, although still in an evolutionary phase, catheter ablation to eliminate atrial fibrillation has been demostrated in the past years to be feasible and clinically useful. On the other hand, innovations in technology and pharmacology, and better preventive and diagnostic tools, have provided our patients with an important improvement in their prognosis. The new developments in molecular genetics and biology are likely to change the way we approach a cardiac patient in the future. The diseases are now being deciphered at the most basic level, and the information obtained opens new possibilities not only for better therapeutic and diagnostic measures but also for prevention of the disease

Integració dels sistemes de classificació de les roques: eina d'aprenentatge transversal per al foment d'equips docents en l'àmbit de la Geologia.

As a response to the need to implement a comprehensive tool for the classification of rocks, an interdisciplinary and interuniversity teaching team formed by teachers and students has been constituted. The team develops teaching actions to improve the university learning on petrology and mineralogy. Such actions will have positive repercussions to undergraduates and postgraduates students as well as to secondary and baccalaureate teachers, and to other professional not directly related to teaching. Moreover, with the implementation of such tool will clearly promote the self-learning of students by means of a uniform and common system of classification of rocks aimed to all types of public

Cardiac resynchronization therapy and valvular cardiomyopathy after corrective surgery

Cardiac resynchronization therapy (CRT) has been shown to have clinical benefits in certain groups of patients with advanced heart failure (HF). However, patients with valvular cardiomyopathy are underrepresented in randomized clinical studies. The aim of this study was to assess the medium-term (i.e., at 6 months) effects of CRT in patients with HF exclusively due to valvular disease. The study included 40 consecutive patients who underwent CRT device implantation. At 6 months, there were improvements in functional class, left ventricular remodeling, and intraventricular dyssynchrony parameters in treated patients. In this particular subgroup of patients, the benefits of CRT were similar to those observed in patients with HF due to other etiologies

Efecto de la localización del electrodo ventricular izquierdo sobre los parámetros ecocardiográficos de asincronía en pacientes sometidos a terapia de resincronización cardíaca

Introduction and objectives. Cardiac resynchronization therapy has been shown to be an option in the treatment of patients with congestive heart failure. The current indication for this treatment is based on clinical and electrocardiographic criteria, although echocardiography has also been shown to be a useful tool for the diagnosis of ventricular dyssynchrony. The aim of this study was to assess left ventricular dyssynchrony by echocardiography and to evaluate the effect of the stimulation site on the magnitude of resynchronization. Patients and method. We studied 25 patients with biventricular stimulation (left ventricular lead located in a lateral position in 13 patients, and in an anterior position in 12). A complete echo-Doppler evaluation, including left ventricular ejection fraction, ventricular diameters and parameters of inter- and intraventricular dyssynchrony, was performed before implantation and 3 months after the procedure, with the device connected and disconnected. Results. Left ventricular ejection fraction increased significantly from 23.7 (6.5) to 27.8 (5.5) (P=.007) at 3 months. In the group as a whole, biventricular pacing was associated with a significant decrease in all intraventricular dyssynchrony parameters (septal-to-lateral wall motion delay and septal-to-posterior wall motion delay). This decrease in septal-to-posterior wall motion delay and septalto- lateral wall motion delay was significantly greater in patients with the electrode implanted in the lateral position (58.1 ms vs 118 ms; P=.02) than with the lead in the anterior position (39.5 ms vs 86.5 ms; P=.04). Three patients, all with the electrode in an anterior location, were considered non-responders. Conclusions. Left lateral free wall stimulation provided significantly better intraventricular resynchronization compared to stimulation at an anterior site. Echocardiography is a useful tool to evaluate changes in intra- and interventricular synchrony related to the pacing site

Obtención de vidrio a partir de residuos de la minería del estaño en Bolivia

Manufacturing of glass from tin mining tailings in Bolivia Tailings from mining activities in Bolivia represent an environmental problem. In the vicinity of the tin mines of Llallagua,Potosí department, there are large dumps and tailings. We present a study of the use of these wastes as raw materials for the manufacture of glass. This procedure aims to contribute to environmental remediation of mining areas through the vitrification, a process which offers an alternative for stabilization of hazardous waste. In addition, the marketing of the obtained product would provide an additional income to the mining areas. For this study three samples of mining waste, with grain size between sand and silt, were used. The chemical composition of these raw materials, determined by X-ray fluorescence, is granitic, with high contents of heavy metals. On the basis of its composition, glass were made from silica glass by adding CaCO3 and Na2CO3. The thermal cycle has been determined from TDA. Tg values of glass range from 626º to 709 °C. Leaching tests of the obtained glasses confirm their capacity to retain heavy metals

Tratamiento de la insuficiencia cardíaca avanzada mediante estimulación biventricular. Experiencia inicial en una serie de 22 casos consecutivos

Recent data suggest that biventricular pacing may play an important role in treating advanced heart failure in the presence of a significant interventricular and/or intraventricular conduction disorder by correcting cardiac dysynchrony. In this article, we review the initial technical and clinical experience with cardiac resynchronization therapy in an electrophysiology laboratory. METHODS: The first 22 consecutive patients with severe congestive heart failure, ejection fraction < 0.35, NYHA functional class III or IV, and QRS duration > 120 ms who were implanted biventricular pacemakers were studied. Clinical, electrocardiographic, and echocardiographic evaluations were made before and three months after pacemaker implantation. Acute functional capacity testing with peak oxygen uptake was measured during biventricular pacing and during intrinsic rhythm or right ventricular pacing three months after the implantation procedure. RESULTS: The success rate of pacemaker implantation was 95%. Pre-discharge left ventricular pacing was achieved in 91%, with an average pacing threshold of 1.53 (1.04) volts. NYHA functional class improved (p = 0.039) from 3.4 (0.7) to 2.3 (0.78). The rate of hospitalization for heart failure decreased from an average of 3.12 (0.58) three months before the procedure to 1.38 (0.34) three months after the procedure. Peak oxygen uptake was significantly greater (p = 0.028) during biventricular pacing: 14.89 (2.1) ml/min/kg, than during intrinsic rhythm or right ventricular pacing: 12.65 (2.3) ml/min/kg. CONCLUSIONS: Cardiac resynchronization therapy can be performed safely and with a high success rate in the electrophysiology laboratory. Biventricular pacing seems to improve the symptoms of congestive heart failure in patients with evidence of atrioventricular and/or interventricular/intraventricular dysynchrony. An acute benefit in peak oxygen uptake was associated with biventricular pacing after the implantation procedure

High-density mapping to guide ablation of a right bundle branch morphology premature ventricular contraction from the right outflow tract

The Rhythmia ultrahigh-density mapping system with a specific algorithm seems to be helpful in identifying the target area to successfully treat multiple morphologies by catheter ablation in the right ventricular outflow tract RVOT. Interestingly, the acquisition process seemed to be extremely faster than a standard manual point-by-point premature ventricular contraction (PVC) mapping