Multiple volcanic eruptions occurred between 8500 and 9000 yr. B.P. from the central crater of CitiaitCpetl Volcano generating a series of pyroclastic flows that formed a deposit with a total volume of about 0.26 km3 (D.R.E.). The flows descended in all directions around the crater, but they were mostly controlled by topography and deposited in valleys or local topographic depressions up to abo...

BACKGROUND AND AIMS This study was aimed at evaluating the effect of different prophylaxis methods on microleak-age of microfilled composite restorations. MATERIALS AND METHODS In this in vitro study, class V cavities were prepared on buccal surfaces of 84 bovine teeth. The teeth were restored with Tetric N-Bond adhesive and Heliomolar composite resin. Subsequent to a thermocycling procedure ...

Pneumoconioses determined by chronic inhalation of different kinds of silica present with peculiar clinical and histopathological features. Silicosis, caused by crystalline silica, is characterized by typical fibrous parenchymal nodules. Less defined are pneumoconioses due to amorphous silica. Aim of current experimental research on silicosis is to investigate the early events that lead to nodu...

"e studies have been performed to analyze the production of β-glucanase by a recombinant strain of Escherichia coli immobilized in di#erent matrices. Porous sintered glass SIRAN®, Ceramic supporting matrices and Broken Pumice stone as well as SIRAN Raschig-rings were examined for the immobilization of whole bacterial cells. "e β-glucanase activity of bacteria immobilized in CeramTec PST 5 (4–5 ...

If the absolute number of poor people goes up, but the fraction of people in poverty comes down, has poverty gone up or gone down? The economist’s instinct, framed by population replication axioms that undergird standard measures of poverty, is to say that in this case poverty has gone down. But this goes against the instinct of those who work directly with the poor, for whom the absolute numbe...

PURPOSE To retrospectively assess the clinical utility in ureteroscopy (URS) planning of cumulative stone diameter (CSD), which does not account for stone width or depth, as a predictor of URS outcome and compare it with stone volume. MATERIALS AND METHODS Patients with renal stones treated at a single institute by flexible URS were retrospectively evaluated. To assess the clinical utility of...

For rehabilitation of damaged concrete structures, the durability of repair overlay is a very important issue. Self-compacting concretes (SCC) are known as a suitable repair overlay materials. In this study, the durability of different self-compacting lightweight aggregate concretes (LWSCC) and effect of lightweight aggregate type on them is investigated. 3 mix designs of LWSCC containing three...

Enamel microabrasion using hydrochloric acid and pumice is an effective method to remove superficial enamel discoloration. This procedure is used in many dental offices but little is known about how different treatment combinations of hand applicator pressure on the tooth, number of applications, and duration of application affect the amount of enamel loss. This investigation studied variables ...

[1] Granular mass flows of rock fragments are studied in the lab by means of a high-speed video camera at 2000 frames per second. These granular flows are generated using beds of pumice fragments positioned on a rough rotating disk, whose angular velocity is controlled by a motor. The experimental apparatus allows an understanding of the arrangement of the particles in granular mass flows with ...

The context for the emergence of life on Earth sometime prior to 3.5 billion years ago is almost as big a puzzle as the definition of life itself. Hitherto, the problem has largely been addressed in terms of theoretical and experimental chemistry plus evidence from extremophile habitats like modern hydrothermal vents and meteorite impact structures. Here, we argue that extensive rafts of glassy...