129 research outputs found
Connecting the evolution of thermally pulsing asymptotic giant branch stars to the chemistry in their circumstellar envelopes - I. Hydrogen cyanide
No full textMonthly Notices of the Royal Astronomical Society
Volume 456, Issue 1, 2016, Pages 23-46
Connecting the evolution of thermally pulsing asymptotic giant branch stars to the chemistry in their circumstellar envelopes - I. Hydrogen cyanide (Article)
Marigo, P.a ,
Ripamonti, E.a,
Nanni, A.a,
Bressan, A.b,
Girardi, L.c
a Department of Physics and Astronomy G. Galilei, University of Padova, Vicolo dell'Osservatorio 3, Padova, Italy
b Astrophysics Sector, SISSA, Via Bonomea 265, Trieste, Italy
c Astronomical Observatory of Padova - INAF, Vicolo dell'Osservatorio 5, Padova, Italy
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Abstract
We investigate the formation of hydrogen cyanide (HCN) in the inner circumstellar envelopes of thermally pulsing asymptotic giant branch (TP-AGB) stars. A dynamic model for periodically shocked atmospheres, which includes an extended chemo-kinetic network, is for the first time coupled to detailed evolutionary tracks for the TP-AGB phase computed with the COLIBRI code. We carried out a calibration of the main shock parameters (the shock formation radius rs,0 and the effective adiabatic index γeff ad) using the circumstellar HCN abundances recently measured for a populous sample of pulsating TP-AGB stars. Our models recover the range of the observed HCN concentrations as a function of the mass-loss rates, and successfully reproduce the systematic increase of HCN moving along the M-S-C chemical sequence of TP-AGB stars, which traces the increase of the surface C/O ratio. The chemical calibration brings along two important implications for the physical properties of the pulsation-induced shocks: (i) the first shock should emerge very close to the photosphere (rs,0 ≃ 1R), and (ii) shocks are expected to have a dominant isothermal character (γ eff ad ≃ 1) in the denser region close to the star (within ~ 3-4R), implying that radiative processes should be quite efficient. Our analysis also suggests that the HCN concentrations in the inner circumstellar envelopes are critically affected by the H-H2 chemistry during the post-shock relaxation stages. Given the notable sensitiveness of the results to stellar parameters, this paper shows that such chemodynamic analyses may indeed provide a significant contribution to the broader goal of attaining a comprehensive calibration of the TP-AGB evolutionary phase
Early Effects of P-15 on Human Bone Marrow Stem Cells
No full textObjectives: Peptide-15 (P-15) is an analogue of the cell binding domain of collagen. P-15 has been shown to facilitate physiological to process in a way similar to collagen, to serve as anchorage for cells, and to promote the binding, migration and differentiation of cells. However, how P-15 alters osteoblast activity to promote bone formation is poorly understood. To study the osteoinductive properties of peptide P-15, we analyzed the expression levels of bone related genes in human mesenchymal stem cells treated with this biomaterial.Material and methods: Using real time Reverse Transcription-Polymerase Chain Reaction the quantitative expression of specific genes, like transcriptional factors (RUNX2 and SP7), bone related genes (SPP1, COL1A1, COL3A1, BGLAP, ALPL, and FOSL1) and mesenchymal stem cells marker (ENG) were examined.Results: P-15 causes a considerable induction of osteoblast transcriptional factor like osterix (SP7) and of the bone related genes osteopontin (SPP1) and osteocalcin (BGLAP). In contrast the expression of endoglin (ENG) was markedly decreased in stem cells treated with P-15 respect to untreated cells, indicating the differentiation effect of this biomaterial on stem cells.Conclusion: The present study shows the effect of P-15 on mesenchymal stem cells in the early differentiation stages: P-15 is an inducer of osteogenesis on human stem cells as indicated by the activation of bone related markers SP7, SPP1 and BGLAP.The results may allow a better understanding of the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects
Aquolab ® ozone-therapy is an efficient adjuvant in the treatment of chronic periodontitis: A case-control study
No full textAim: The objective of this study was to compare the efficacy of supportive periodontal therapy (i.e., scaling and root planning [SRP]) alone versus Aquolab ® ozone therapy used in association with SRP in the treatment of chronic periodontitis in adult patients. Materials and Methods: A total of 20 patients with a diagnosis of chronic periodontitis (40 localized chronic periodontitis sites) were enrolled. None of these patients have previously received any surgical or nonsurgical periodontal therapy and demonstrated radiographic evidence of moderate bone loss. Two nonadjacent sites in separate quadrants were selected in each patient to verify treatment efficacy (split-mouth design). Microbial analysis was analyzed at baseline and the 7 th day after treatment. SPSS program and paired simple statistic t-test were used to detect statistically significant differences. Results: There was a statistically significant reduction of Tannerella forsythia loading in sites treated with ozone therapy respect to those treated with SPR alone. A similar trend was obtained also for additional 5 species and for total bacterial loading (CBT). These results were obtained with a single local application of ozone therapy just after SPR and with a molecular control 7 th day after treatment. Conclusion : Aquolab ® ozone therapy in is effective in reducing the CBT in pockets of patients affected by periodontitis. It is an efficacy medical device to be used as adjuvant therapy to be added to SRP in the management of moderate to severe chronic periodontitis
Evolution of thermally pulsing asymptotic giant branch stars - II. Dust production at varying metallicity
No full textWe present the dust ejecta of the new stellar models for the thermally pulsing asymptotic giant branch (TP-AGB) phase computed with the COLIBRI code. We use a formalism of dust growth coupled with a stationary wind for both M- and C-stars. In the original version of this formalism, the most efficient destruction process of silicate dust in M-giants is chemisputtering by H2 molecules. For these stars, we find that dust grains can only form at relatively large radial distances (r ̃ 5R*), where they cannot be efficiently accelerated, in agreement with other investigations. In the light of recent laboratory results, we also consider the alternative case that the condensation temperature of silicates is determined only by the competition between growth and free evaporation processes (i.e. no chemisputtering). With this latter approach we obtain dust condensation temperatures that are significantly higher (up to Tcond ̃ 1400 K) than those found when chemisputtering is included (Tcond ̃ 900 K), and in better agreement with condensation experiments. As a consequence, silicate grains can remain stable in inner regions of the circumstellar envelopes (r ̃ 2 R*), where they can rapidly grow and can be efficiently accelerated. With this modification, our models nicely reproduce the observed trend between terminal velocities and mass-loss rates of Galactic M-giants.
For C-stars the formalism is based on the homogeneous growth scheme where the key role is played by the carbon over oxygen excess. The models reproduce fairly well the terminal velocities of Galactic stars and there is no need to invoke changes in the standard assumptions. At decreasing metallicity the carbon excess becomes more pronounced and the efficiency of dust formation increases. This trend could be in tension with recent observational evidence in favour of a decreasing efficiency, at decreasing metallicity. If confirmed by more observational data, it would indicate that either the amount of the carbon excess, determined by the complex interplay between mass-loss, third dredge-up and hot-bottom burning, or the homogeneous growth scheme should be revised. Finally, we analyse the differences in the total dust production of M-stars that arise from the use of the two approaches (i.e. with or without chemisputtering). We find that, in spite of the differences in the expected dust stratification, for a given set of TP-AGB models, the ejecta are only weakly sensitive to the specific assumption. This work also shows that the properties of TP-AGB circumstellar envelopes are important diagnostic tools that may be profitably added to the traditional calibrators for setting further constraints on this complex phase of stellar evolution
Titanium nanotubes stimulate osteoblast differentiation of stem cells from pulp and adipose tissue
No full textBACKGROUND:
Titanium is the gold standard among materials used for prosthetic devices because of its good mechanical and chemical properties. When exposed to oxygen, titanium becomes an oxide, anatase that is biocompatible and able to induce osseointegration.
MATERIALS AND METHODS:
IN THIS STUDY WE COMPARED THE EXPRESSION PROFILING OF STEM CELLS CULTIVATED ON TWO TYPES OF SURFACE: Pure titanium disk and nanotube titanium disk in order to detect if nanotube titanium instead (NTD) surface stimulates stem cells towards osteoblast differentiation.
RESULTS:
Stem cells cultivated on nanotube titanium disks showed the upregulation of bone-related genes RUNX2, FOSL1 and SPP1.
CONCLUSIONS:
Results demonstrated that nanotube titanium disk surface is more osteo-induced surface compared to titanium disk, promoting the differentiation of mesenchymal stem cells in osteoblasts
UN ESPERIMENTO DI PEDAGOGIA CIVILE: il Master dell’Università Parthenope per “Educatori sportivi per la prevenzione del rischio” AN EXPERIMENT OF CIVIL EDUCATION: the Master of Parthenope University in “Sports educator for risk prevention”
No full textIn the socio-pedagogical research the identified correlation between education poverty and social risk outlines the alarming need of training and having effective educators able to promote and adopt interventions in this area and consequent deviance risk. Starting from these considerations, the Parthenope University has designed and implemented the first national Master’s Degree Program specifically addressed to train “Motor and Sports educators for social inclusion and risk prevention”. This training project derives from the shared idea that sport, especially a much more aware use of the human body, represents a powerful formative and self-regulating device in the struggle against educational poverty, for the reduction of discomfort and risk prevention. This paper, within this scenario, goes through the content, method and evaluation aspects of the training experience carried out, in a shared vision of “civil pedagogy” and “education for territoriality”
Comparison of Bio-Revitalizing Injective Products: A Study on Skin Fibroblast Cultures
No full textBio-revitalization is a commonly used technique in aesthetic medicine for improving skin quality and appearance by intra-dermal injection of hyaluronic acid (HA)-containing compounds. The present study compares different HA-containing injectables regarding their effects on cultured skin fibroblasts over time (24, 48, and 72 hr) by using RT-PCR and a panel of genes involved in dermal integrity. Human dermal fibroblasts were seeded on a layer of five different commercial medical devices containing 6.2 mg/mL 10 mg/mL 10%, 13 mg/mL and 20 mg/mL, respectively, of HA. The products differ not only in HA concentration but also in the content and quality of other ingredients; moreover, one of these products contained cross-linked HA. Differences among medical devices were found. In particular, HA concentration seems to be inversely correlated to elastin gene activation. Regarding the neutrophil elastase gene, the two medical devices with the higher concentration of HA displayed the greater effect. Genes encoding for hyaluronan synthase 1, hyaluronidase 1, and desmoplakin were enhanced, but the HA content of the different products did not seem to be directly related to gene activation. Therefore, the explanation for the differences must be studied further with respect to elements that are distinctive for each device. For the physician, it is important to choose which drugs or medical devices can be used and in what protocols. The present study performed a comparison that can be useful in better addressing the skin improvement therapies for aging and in its prevention
Evolution of thermally pulsing asymptotic giant branch stars - III. Dust production at supersolar metallicities
No full textWe extend the formalism presented in our recent calculations of dust ejecta from the Thermally Pulsing Asymptotic Giant Branch (TP-AGB) phase to the case of super-solar metallicity stars. The TP-AGB evolutionary models are computed with the COLIBRI code. We adopt our preferred scheme for dust growth. For M-giants, we neglect chemisputtering by H2 molecules and for C-stars we assume a homogeneous growth scheme which is primarily controlled by the carbon over oxygen excess. At super-solar metallicities, dust forms more efficiently and silicates tend to condense significantly closer to the photosphere (r ̃ 1.5R*) - and thus at higher temperatures and densities - than at solar and sub-solar metallicities (r ̃ 2-3R*). In such conditions, the hypothesis of thermal decoupling between gas and dust becomes questionable, while dust heating due to collisions plays an important role. The heating mechanism delays dust condensation to slightly outer regions in the circumstellar envelope. We find that the same mechanism is not significant at solar and sub-solar metallicities. The main dust products at super-solar metallicities are silicates. We calculate the total dust ejecta and dust-to-gas ejecta, for various values of the stellar initial masses and initial metallicities Z = 0.04, 0.06. Merging these new calculations with those for lower metallicities it turns out that, contrary to what is often assumed, the total dust-to-gas ejecta of intermediate-mass stars exhibit only a weak dependence on the initial metal content
Bio-Revitalization: Effects of NASHA on Genes Involving Tissue Remodeling
No full textThe "non-animal stabilized hyaluronic acid" (NASHA) is a widely used product in bio-revitalization injective procedures in esthetic medicine. The present research aimed to quantitatively evaluate the therapeutic effect of one of the more used bio-revitalization products on cultured dermal fibroblasts. RT-PCR was used for gene expression profiling of some proteins known to be relevant in skin homeostasis
Anatase-based implants nanocoating on stem cells derived from adipose tissue
No full textPurpose: The aim of this study was to investigate the effect of a new anatase coating with antibacterial properties (Bactercline anatase coating [BAC]) on dental implants in the commitment of stem cells derived from adipose tissue to osteoblasts. Materials and Methods: Using real-time reverse transcription polymerase chain reaction, the quantitative expression of specific genes, such as transcriptional factors (runx2 and sp7), bone-related genes (spp1, col1a1, col3a1, alpl, and fosl1), and mesenchymal stem cells marker (eng), was examined. Results: BAC caused induction of bone-related genes such as sp7, fosl1, alpl, and spp1. In contrast, the expression of runx2, col3a1, and col1a1 was decreased in stem cells treated with BAC with respect to untreated cells. Conclusion: The obtained results are relevant to better understand the molecular mechanism of bone regeneration and as a model for comparing other materials with similar clinical effects. Copyright © 2012 by Lippincott Williams & Wilkins
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