Contact Joints Shear Strength of Composite Concrete Structures Laced with STACHEMENT-2000M Hyperplasticizer

The urgency of using composite concrete and reinforced concrete structures and the problem of solid adhesion of the element in the zone of the contact joint of composite concrete and reinforced concrete structures are considered in the article. The investigations of contact joints shear strength laced with STACHEMENT-2000M hyperplasticizer are carried out. Conclusions are drawn from the results obtained

Technique of realizing academic conditions of reflexive attitude formation for a prospective foreign language teacher in the course of professional training

The article presents the authors’ technology of realization of pedagogical conditions (actualization of reflexive life experience of a future teacher of a foreign language in situations of pedagogical interaction by means of problem-variable construction of lessons; involvement of the future foreign language teacher in educational professionally-oriented activities through the solution of reflexive and professional tasks; the use of interactive forms of training to work out the reflection algorithm as a means of entering into a reflective position of the future foreign language teacher

The stability of hydrous silicates in Earth's lower mantle:Experimental constraints from the systems MgO-SiO₂-H₂O and MgO-Al₂O₃-SiO₂-H₂O

AbstractWe performed laser-heated diamond anvil cell experiments on bulk compositions in the systems MgO–SiO2–H2O (MSH) and MgO–Al2O3–SiO2–H2O (MASH) that constrain the stability of hydrous phases in Earth's lower mantle. Phase identification by synchrotron powder diffraction reveals a consistent set of stability relations for the high-pressure, dense hydrous silicate phases D and H. In the MSH system phase D is stable to ~50GPa, independent of temperature from ~1300 to 1700K. Phase H becomes stable between 35 and 40GPa, and the phase H out reaction occurs at ~55GPa at 1600K with a negative dT/dP slope of ~−75K/GPa. Between ~30 and 50GPa dehydration melting occurs at ~1800K with a flat dT/dP slope. A cusp along the solidus at ~50GPa corresponds with the intersection of the subsolidus phase H out reaction, and the dT/dP melting slope steepens to ~15K/GPa up to ~85GPa.In the MASH system phase H is stable in experiments between ~45 and 115GPa in all bulk compositions studied, and we expect aluminous phase H to be stable throughout the lower mantle depth range beneath ~1200km in both peridotitic and basaltic lithologies. In the subsolidus, aluminous phase D is stable to ~55GPa, whereas at higher pressures aluminous phase H is the stable hydrous phase. The presence of hydrogen may sharpen the bridgmanite to post-perovskite transition. The ambient unit cell volume of bridgmanite increases systematically with pressure above ~55GPa, possibly representing an increase in alumina content, and potentially hydrogen content, with depth. Bridgmanite in equilibrium with phases D and H has a relatively low alumina content, and alumina partitions preferentially into the hydrous phases. The melting curves of MASH compositions are shallower than in the MSH system, with dT/dP of ~6K/GPa. Phase D and H solid solutions are stable in cold, hydrated subducting slabs and can deliver water to the deepest lower mantle. However, hydrated lithologies in the lower mantle are likely to be partially molten at all depths along an ambient mantle geotherm

Crustal-scale degassing due to magma system destabilization and magma-gas decoupling at Soufrière Hills Volcano, Montserrat

Activity since 1995 at Soufrière Hills Volcano (SHV), Montserrat has alternated between andesite lava extrusion and quiescence, which are well correlated with seismicity and ground deformation cycles. Large variations in SO₂ flux do not correlate with these alternations, but high and low HCl/SO₂ characterize lava dome extrusion and quiescent periods respectively. Since lava extrusion ceased (February 2010) steady SO₂ emissions have continued at an average rate of 374 tonnes/day (± 140 t/d), and incandescent fumaroles (temperatures up to 610°C) on the dome have not changed position or cooled. Occasional short bursts (over several hours) of higher (∼ 10x) SO₂ flux have been accompanied by swarms of volcano-tectonic earthquakes. Strain data from these bursts indicate activation of the magma system to depths up to 10 km. SO₂ emissions since 1995 greatly exceed the amounts that could be derived from 1.1 km³ of erupted andesite, and indicating extensive partitioning of sulfur into a vapour phase, as well as efficient decoupling and outgassing of sulfur-rich gases from the magma. These observations are consistent with a vertically extensive, crustal magmatic mush beneath SHV. Three states of the magmatic system are postulated to control degassing. During dormant periods (10³ to 10⁴ years) magmatic vapour and melts separate as layers from the mush and decouple from each other. In periods of unrest (years) without eruption, melt and fluid layers become unstable, ascend and can amalgamate. Major destabilization of the mush system leads to eruption, characterized by magma mixing and release of volatiles with different ages, compositions and sources.RSJS acknowledges an ERC advanced grant (VOLDIES). JDB acknowledges ERC advanced grant CRITMAG and a Wolfson Research Merit Award.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/2015GC00579

Technique of realizing academic conditions of reflexive attitude formation for a prospective foreign language teacher in the course of professional training

The article presents the authors’ technology of realization of pedagogical conditions (actualization of reflexive life experience of a future teacher of a foreign language in situations of pedagogical interaction by means of problem-variable construction of lessons; involvement of the future foreign language teacher in educational professionally-oriented activities through the solution of reflexive and professional tasks; the use of interactive forms of training to work out the reflection algorithm as a means of entering into a reflective position of the future foreign language teacher