136 research outputs found
Organic Molecules in Low-Mass Protostellar Hot Cores: Submillimeter Imaging of IRAS 16293-2422
Arcsecond-resolution spectral observations toward the protobinary system IRAS
16293-2422 at 344 and 354 GHz were conducted using the Submillimeter Array.
Complex organic molecules such as CH3OH and HCOOCH3 were detected. Together
with the rich organic inventory revealed, it clearly indicates the existence of
two, rather than one, compact hot molecular cores (smaller than or equal to 400
AU in radius) associated with each of the protobinary components identified by
their dust continuum emission in the inner star-forming core.Comment: 11 pages, 3 figures, to be published in ApJ
Evaporation kinetics in swollen porous polymeric networks
Ponencia presentada en el Congreso Euromar 2014.Fil: Velasco, Manuel Isaac. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Silletta, Emilia Victoria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Monti, Gustavo Alberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Acosta, Rodolfo HĂ©ctor. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Velasco, Manuel Isaac. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Silletta, Emilia Victoria. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Monti, Gustavo Alberto. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Acosta, Rodolfo HĂ©ctor. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Departamento de QuĂmica OrgĂĄnica; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Departamento de QuĂmica OrgĂĄnica; Argentina.Fil: Gomez, Cesar Gerardo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Polymer matrices with well defined structure and pore sizes are widely used in several areas of chemistry such as catalysis, enzyme immobilization, HPLC, adsorbents or controlled drug release. These polymers have pores in its structure both in the dry and swollen state. Although it is well known that the structures and properties greatly differ between these two states, only few methods provide information about the swollen one, even though most of the applications involve the matrices in this situation. Nuclear Magnetic Resonance (NMR) is a suitable tool for the study of the molecular dynamics of different liquids spatially confined in macro, meso and nanopores, through changes in the relaxation times. In transverse relaxation experiments, either diffusion inside the pore, or relaxation induced by mobility restriction of the liquid near the wall, are additional
sources of relaxation, which are extremely useful in the determination of structural and functional properties.Fil: Velasco, Manuel Isaac. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Silletta, Emilia Victoria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Monti, Gustavo Alberto. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Acosta, Rodolfo HĂ©ctor. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de FĂsica Enrique Gaviola; Argentina.Fil: Velasco, Manuel Isaac. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Silletta, Emilia Victoria. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Monti, Gustavo Alberto. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Acosta, Rodolfo HĂ©ctor. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂa y FĂsica; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Departamento de QuĂmica OrgĂĄnica; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de CĂłrdoba. Facultad de Ciencias QuĂmicas. Departamento de QuĂmica OrgĂĄnica; Argentina.Fil: Gomez, Cesar Gerardo. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de CĂłrdoba. Instituto Multidisciplinario de BiologĂa Vegetal; Argentina.FĂsica de los Materiales Condensado
Comprehensive in vitro and in vivo studies of novel melt-derived Nb-substituted 45S5 bioglass reveal its enhanced bioactive properties for bone healing
The present work presents and discusses the results of a comprehensive study on the bioactive properties of Nb-substituted silicate glass derived from 45S5 bioglass. In vitro and in vivo experiments were performed. We undertook three different types of in vitro analyses: (i) investigation of the kinetics of chemical reactivity and the bioactivity of Nb-substituted glass in simulated body fluid (SBF) by 31P MASNMR spectroscopy, (ii) determination of ionic leaching profiles in buffered solution by inductively coupled plasma optical emission spectrometry (ICP-OES), and (iii) assessment of the compatibility and osteogenic differentiation of human embryonic stem cells (hESCs) treated with dissolution products of different compositions of Nb-substituted glass. The results revealed that Nb-substituted glass is not toxic to hESCs. Moreover, adding up to 1.3âmol% of Nb2O5 to 45S5 bioglass significantly enhanced its osteogenic capacity. For the in vivo experiments, trial glass rods were implanted into circular defects in rat tibia in order to evaluate their biocompatibility and bioactivity. Results showed all Nb-containing glass was biocompatible and that the addition of 1.3âmol% of Nb2O5, replacing phosphorous, increases the osteostimulation of bioglass. Therefore, these results support the assertion that Nb-substituted glass is suitable for biomedical applications
The TOP-SCOPE Survey of Planck Galactic Cold Clumps : Survey Overview and Results of an Exemplar Source, PGCC G26.53+0.17
The low dust temperatures (<14 K) of Planck Galactic cold clumps (PGCCs) make them ideal targets to probe the initial conditions and very early phase of star formation. "TOP-SCOPE" is a joint survey program targeting similar to 2000 PGCCs in J = 1-0 transitions of CO isotopologues and similar to 1000 PGCCs in 850 mu m continuum emission. The objective of the "TOP-SCOPE" survey and the joint surveys (SMT 10 m, KVN 21 m, and NRO 45 m) is to statistically study the initial conditions occurring during star formation and the evolution of molecular clouds, across a wide range of environments. The observations, data analysis, and example science cases for these surveys are introduced with an exemplar source, PGCC G26.53+0.17 (G26), which is a filamentary infrared dark cloud (IRDC). The total mass, length, and mean line mass (M/L) of the G26 filament are similar to 6200 M-circle dot, similar to 12 pc, and similar to 500 M-circle dot pc(-1), respectively. Ten massive clumps, including eight starless ones, are found along the filament. The most massive clump as a whole may still be in global collapse, while its denser part seems to be undergoing expansion owing to outflow feedback. The fragmentation in the G26 filament from cloud scale to clump scale is in agreement with gravitational fragmentation of an isothermal, nonmagnetized, and turbulent supported cylinder. A bimodal behavior in dust emissivity spectral index (beta) distribution is found in G26, suggesting grain growth along the filament. The G26 filament may be formed owing to large-scale compression flows evidenced by the temperature and velocity gradients across its natal cloud.Peer reviewe
Conductivity/activation energy relationships for cement-based materials undergoing cyclic thermal excursions
The electrical conductivity of a range of concrete
mixes, with and without supplementary cementitious
materials (SCM), is studied through multiple cycles of
heating and cooling over the extended temperature range
-30/?70 C. When presented in an Arrhenius format, the
experimental results display hysteresis effects at the lowtemperature
end of the thermal cycle and, in those concretes
containing supplementary cementitious materials at
higher water/binder ratios, hysteresis effects were evident
over the entire temperature range becoming more discernible
with increasing number of thermal cycles. The
depression in both the freezing and thawing point could be
clearly identified and was used to estimate pore-neck and
pore-cavity radii. A simplified approach is presented to
evaluate the volumetric ratio of frozen pore water in terms
of conductivity measurements. The results also show that
the conductivity and activation energy of the concrete
specimens were related to the water/binder ratio, type of
SCM, physical state of the pore water and the thermal
cycling regime
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