90 research outputs found
A novel hybrid material with calcium and strontium release capability
The preparation of PDMSâTEOSâCaO hybrid materials by solâgel techniques has been widely described in
previous works. Calcium nitrate is the most common source of calcium used in these preparations.
However, to remove possible toxic nitrate by-products a thermal treatment is necessary at temperatures
above 500 1C, which leads to the degradation of the polymeric components of the hybrids. Strontium has
already shown some promising results in the therapeutic area, being used in cases of osteoporosis and low
bone density. In this study a new potential bioactive hybrid material was prepared, by solâgel techniques,
using calcium acetate as a novel calcium source. Also, for the first time, incorporation of strontium in a
PDMSâTEOS hybrid system was evaluated. Samples were characterized before and after immersion in
Kokuboâs Simulated Body Fluid (SBF) by SEM, EDS, ICP and FT-IR spectroscopy
Correlation of mixed lymphocyte culture with chronic graft-versus-host disease following allogeneic stem cell transplantation
The purpose of the present study was to evaluate the mixed lymphocyte culture as a predictive assay of acute and chronic graft-versus-host disease (GVHD). We studied 153 patients who received a first bone marrow transplantation from human leukocyte antigen-identical siblings. Acute GVHD was observed in 26 of 128 (20.3%) patients evaluated and chronic GVHD occurred in 60 of 114 (52.6%). One-way mixed lymphocyte culture (MLC) assays were performed by the standard method. MLC results are reported as the relative response (RR) from donor against patient cells. The responses ranged from -47.0 to 40.7%, with a median of 0.5%. The Kaplan-Meier probability of developing GVHD was determined for patients with positive and negative MLC. There was no significant difference in incidence of acute GVHD between the groups studied. However, the incidence of chronic GVHD was higher in recipients with RR >4.5% than in those with RR 4.5%), 2.9 for those who received peripheral blood progenitor cells as a graft, and 2.2 for patients who developed previous acute GVHD. MLC was not useful for predicting acute GVHD, but MLC with RR >4.5% associated with other risk factors could predict the development of chronic GVHD, being of help for the prevention and/or treatment of this late complication.56757
The availability of full match sibling donors and feasibility of allogeneic bone marrow transplantation in Brazil
The feasibility of allogeneic bone marrow transplantation (alloBMT) in a developing country has not yet been demonstrated. Many adverse factors including social and economic limitations may reduce the overall results of this complex and expensive procedure. Our objective was to characterize the most important clinical, social and economic features of candidates for transplantation and their potential donors as well as the influence of these factors on overall survival in a retrospective and exploratory analysis at a university hospital. From July 1993 to July 2001, candidates for BMT were referred to the Bone Marrow Transplantation Unit by Hematology and Oncology Centers from several regions of Brazil. A total of 1138 patients were referred to us as candidates for alloBMT. Median age was 25 years (range: 2 months-60 years), 684 (60.1%) were males and 454 (39.9%) were females. The clinical indications were severe aplastic anemia and hematological malignancies. From the total of 1138 patients, 923 had HLA-typing; 497/923 (53.8%) candidates had full match donors; 352/1138 (30.8%) were eligible for alloBMT. Only 235 of 352 (66.7%) were transplanted. Schooling was 1st to 8th grade for 123/235 (52.3%); monthly family income ranged from US400 (36%). Overall survival for patients with chronic myeloid leukemia, severe aplastic anemia and acute myeloid leukemia was 58, 60 and 30%, respectively. Thus, overall survival rates for the most frequent hematological diseases were similar to those reported in the International Registry, except for acute myeloid leukemia. This descriptive and exploratory analysis suggests the feasibility of alloBMT in a developing country like Brazil.31532
Black-hole quasinormal modes and scalar glueballs in a finite-temperature AdS/QCD model
We use the holographic AdS/QCD soft-wall model to investigate the spectrum of
scalar glueballs in a finite temperature plasma. In this model, glueballs are
described by a massless scalar field in an AdS_5 black hole with a dilaton
soft-wall background. Using AdS/CFT prescriptions, we compute the boundary
retarded Green's function. The corresponding thermal spectral function shows
quasiparticle peaks at low temperatures. We also compute the quasinormal modes
of the scalar field in the soft-wall black hole geometry. The temperature and
momentum dependences of these modes are analyzed. The positions and widths of
the peaks of the spectral function are related to the frequencies of the
quasinormal modes. Our numerical results are found employing the power series
method and the computation of Breit-Wigner resonances.Comment: Revision: Results unchanged. More discussions on the model and on the
results. References added. 28 pages, 7 figures, 5 table
Singularities of bi-Hamiltonian systems
We study the relationship between singularities of bi-Hamiltonian systems and
algebraic properties of compatible Poisson brackets. As the main tool, we
introduce the notion of linearization of a Poisson pencil. From the algebraic
viewpoint, a linearized Poisson pencil can be understood as a Lie algebra with
a fixed 2-cocycle. In terms of such linearizations, we give a criterion for
non-degeneracy of singular points of bi-Hamiltonian systems and describe their
types
Structural, physiognomic and aboveground biomass variation in savanna-forest transition zones on three continents. How different are co-occuring savanna and forest formations?
Densidade da madeira de ĂĄrvores em savanas do norte da AmazĂŽnia brasileira
Densidade da madeira (DM) Ă© uma variĂĄvel importante para estimativas de estoques de carbono arbĂłreo em ecossistemas terrestres. Este tema Ă© pobremente investigado em ĂĄreas de savana da AmazĂŽnia brasileira. O objetivo deste estudo foi investigar a DM das oito principais espĂ©cies arbĂłreas que ocorrem na savana aberta de Roraima, a maior ĂĄrea de savana do norte do bioma AmazĂŽnia. Foram verificadas as variaçÔes na DM em função da espĂ©cie e dos diferentes diĂąmetros observados ao longo da dimensĂŁo vertical de 75 indivĂduos amostrados em seis sĂtios de coleta. Foi utilizado o mĂ©todo direto para obtenção de peças de madeira do fuste e da copa. Os resultados indicaram discrepĂąncia significativa interespecĂfica, sendo Roupala montana Aubl. a espĂ©cie de maior DM mĂ©dia (0,674 g cm-3). Foi detectado que existe variação significativa da DM entre as peças do fuste e da copa, independente da espĂ©cie e do sĂtio de coleta. A densidade da madeira de peças da copa com diĂąmetro entre 5 e 10 cm pode ser utilizada como preditora da DM mĂ©dia do indivĂduo arbĂłreo. NĂłs concluimos que a DM das oito espĂ©cies arbĂłreas investigadas possui variabilidade interespecĂfica, com discrepĂąncias entre a DM do fuste e das partes lenhosas da copa. As distinçÔes aqui detectadas devem ser considerados como uma importante ferramenta para melhorar as estimativas de estoque de carbono em ĂĄreas de savanas na AmazĂŽnia
DinĂąmica de decomposição e mineralização de nitrogĂȘnio em função da qualidade de resĂduos de gramĂneas e leguminosas forrageiras
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