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排序方式: 共有1736条查询结果,搜索用时 15 毫秒
31.
Italo Odone Mazali Luiz Carlos Barbosa Oswaldo Luiz Alves 《Journal of Materials Science》2004,39(6):1987-1995
In the present work we describe the synthesis, spectroscopy, thermal and chemical durability properties of the vitreous system Li2O-Nb2O5-CaO-P2O5 (LNCP). Investigations of the short-range order by Fourier transform infrared, Raman, UV-VIS and 31P MAS-NMR spectroscopies suggest that the network former glass consists of Nb octahedra linked to pyro/orthophosphate units through Nb—O—P bonds. The presence of modifier cations (Li+ and Ca2+) promotes depolymerization of the P—O—P chains, yielding pyro/orthophosphate units. The presence of this kind of structure accounts for the improvement of the chemical durability at low pH when the Nb content in the LNCP glass composition is high. The density and linear refractive indices of LNCP glasses increased linearly as the Nb2O5/P2O5 molar ratio increased, as a consequence of P2O5 substitution by Nb2O5 as the glassformer. The dependence of the glass transition temperature, the softening temperature and the crystallization temperature on the Nb2O5/P2O5 ratio exhibits the same behavior. On the other hand, the thermal expansion coefficient decreases with the increased Nb2O5/P2O5 ratio. 相似文献
32.
Mariana P. Pinho Guilherme A. Lepski Roberta Rehder Nadia E. Chauca-Torres Gabriela C. M. Evangelista Sarah F. Teixeira Elizabeth A. Flatow Jaqueline V. de Oliveira Carla S. Fogolin Nataly Peres Analía Arvalo Venncio Alves Jos A. M. Barbuto Patricia C. Bergami-Santos 《International journal of molecular sciences》2022,23(10)
Immunotherapy has brought hope to the fight against glioblastoma, but its efficacy remains unclear. We present the case of CST, a 25-year-old female patient with a large right-hemisphere glioblastoma treated with a dendritic–tumor cell fusion vaccine. CST showed a near-complete tumor response, with a marked improvement in her functional status and simultaneous increases in tumor-specific CD8+ and CD4+ T cells. Two months before recurrence, the frequency of tumor-specific T cells decreased, while that of IL-17 and CD4+ T cells increased. CST passed away 15 months after enrollment. In this illustrative case, the tumor-specific CD4+ T-cell numbers and phenotype behaved as treatment efficacy biomarkers, highlighting the key role of the latter in glioblastoma immunotherapy. 相似文献
33.
Gabriel Alves Bonaf Jssica Silva dos Santos Jussara Vaz Ziegler Fernando Augusto Lima Marson Thalita Rocha Manoela Marques Ortega 《International journal of molecular sciences》2022,23(13)
Glycyrrhizic acid (GA), a natural compound isolated from licorice (Glycyrrhiza glabra), has exhibited anti-inflammatory and anti-tumor effects in vitro. Dipotassium glycyrrhizinate (DPG), a dipotassium salt of GA, also has shown an anti-tumor effect on glioblastoma cell lines, U87MG and T98G. The study investigated the DPG effects in the melanoma cell line (SK-MEL-28). MTT assay demonstrated that the viability of the cells was significantly decreased in a time- and dose-dependent manner after DPG (IC50 = 36 mM; 24 h). DNA fragmentation suggested that DPG (IC50) induced cellular apoptosis, which was confirmed by a significant number of TUNEL-positive cells (p-value = 0.048) and by PARP-1 [0.55 vs. 1.02 arbitrary units (AUs), p-value = 0.001], BAX (1.91 vs. 1.05 AUs, p-value = 0.09), and BCL-2 (0.51 vs. 1.07 AUs, p-value = 0.0018) mRNA compared to control cells. The proliferation and wound-healing assays showed an anti-proliferative effect on DPG-IC50-treated cells, also indicating an inhibitory effect on cell migration (p-values < 0.001). Moreover, it was observed that DPG promoted a 100% reduction in melanospheres formation (p-value = 0.008). Our previous microRNAs (miRs) global analysis has revealed that DPG might increase miR-4443 and miR-3620 expression levels. Thus, qPCR showed that after DPG treatment, SK-MEL-28 cells presented significantly high miR-4443 (1.77 vs. 1.04 AUs, p-value = 0.02) and miR-3620 (2.30 vs. 1.00 AUs, p-value = 0.01) expression compared to control cells, which are predicted to target the NF-kB, CD209 and TNC genes, respectively. Both genes are responsible for cell attachment and migration, and qPCR revealed significantly decreased CD209 (1.01 vs. 0.54 AUs, p-value = 0.018) and TNC (1.00 vs. 0.31 AUs, p-value = 2.38 × 10−6) mRNA expression levels after DPG compared to untreated cells. Furthermore, the migration of SK-MEL-28 cells stimulated by 12-O-tetradecanoylphorbol-13-acetate (TPA) was attenuated by adding DPG by wound-healing assay (48 h: p-value = 0.004; 72 h: p-value = 7.0 × 10−4). In addition, the MMP-9 expression level was inhibited by DPG in melanoma cells stimulated by TPA and compared to TPA-treated cells (3.56 vs. 0.99 AUs, p-value = 0.0016) after 24 h of treatment. Our results suggested that DPG has an apoptotic, anti-proliferative, and anti-migratory effect on SK-MEL-28 cells. DPG was also able to inhibit cancer stem-like cells that may cause cerebral tumor formation. 相似文献
34.
D. S. Alves J. L. G. Pereira C. L. De Sousa J. V. Soares F. Yamaguchi 《International journal of remote sensing》2013,34(14):2877-2882
An analysis of landscape changes in a region of pioneer settlements in central Rondonia, western Brazilian Amazon, was derived from Landsat TM data. Total deforested area increased from 206 x 103 ha in 1977, to 565 x 103 ha in 1985 and to 1210 x 103 ha, or 35.5% of the region, in 1995. Eighty-one per cent of the total 1995 deforestation had occurred in regions within 12.5km from areas of pioneer colonization deforested by 1977. Deforested area exceeded 79% in regions within 12.5km from the region's first road. 相似文献
35.
Leonardo Rocha Fernando Mourão Hilton Mota Thiago Salles Marcos André Gonçalves Wagner Meira Jr. 《Information Systems》2013
The management of a huge and growing amount of information available nowadays makes Automatic Document Classification (ADC), besides crucial, a very challenging task. Furthermore, the dynamics inherent to classification problems, mainly on the Web, make this task even more challenging. Despite this fact, the actual impact of such temporal evolution on ADC is still poorly understood in the literature. In this context, this work concerns to evaluate, characterize and exploit the temporal evolution to improve ADC techniques. As first contribution we highlight the proposal of a pragmatical methodology for evaluating the temporal evolution in ADC domains. Through this methodology, we can identify measurable factors associated to ADC models degradation over time. Going a step further, based on such analyzes, we propose effective and efficient strategies to make current techniques more robust to natural shifts over time. We present a strategy, named temporal context selection, for selecting portions of the training set that minimize those factors. Our second contribution consists of proposing a general algorithm, called Chronos, for determining such contexts. By instantiating Chronos, we are able to reduce uncertainty and improve the overall classification accuracy. Empirical evaluations of heuristic instantiations of the algorithm, named WindowsChronos and FilterChronos, on two real document collections demonstrate the usefulness of our proposal. Comparing them against state-of-the-art ADC algorithms shows that selecting temporal contexts allows improvements on the classification accuracy up to 10%. Finally, we highlight the applicability and the generality of our proposal in practice, pointing out this study as a promising research direction. 相似文献
36.
A. Magnus G. Carvalho A.A. CoelhoP.J. von Ranke C.S. Alves 《Journal of Alloys and Compounds》2011,509(8):3452-3456
The determination of the isothermal variation of the entropy (ΔST) is discussed in the present work. We show that ΔST has very different profiles and magnitudes when calculated from M vs. H or M vs. T experimental data. For MnAs compound, ΔST obtained from M vs. T data does not present a colossal peak. This result and the agreement between theoretical and experimental non-colossal magnetocaloric effect indicate that the colossal peak may be miscalculated from M vs. H experimental data. For Gd5Ge2Si2 compound, ΔST obtained from M vs. T data does not present the peak observed in ΔST from M vs. H data. 相似文献
37.
S.M.C. MirandaM. Peres T. MonteiroE. Alves H.D. SunT. Geruschke R. ViandenK. Lorenz 《Optical Materials》2011,33(7):1139-1142
Zinc oxide epilayers grown by metal organic vapour phase epitaxy on (0 0 0 1) sapphire substrates were doped with Praseodymium and Europium by ion implantation. The as-implanted samples were either annealed in air for 20 min in a tube furnace or rapid thermal annealing (RTA) was performed, for 2 min, in a nitrogen atmosphere. The samples were characterized by Rutherford Backscattering Spectrometry/Channelling and photoluminescence. The presented results indicate that in the as-implanted samples the majority of the rare earth (RE) ions are incorporated into substitutional Zn-sites. Furnace annealing at 1000 °C recovers the crystal quality of the samples but leads to an out-diffusion of the RE. RTA suppresses diffusion but lattice damage is not fully recovered at 1000 °C. More importantly, during RTA the RE ions are driven from the substitutional site and are now found mainly on random interstitial sites and no optical activation could be achieved. 相似文献
38.
Davinson Mariano da Silva Luciana Reyes Pires Kassab Massimo Olivero Thiago B.N. Lemos Douglas V. da Silva A.S.L. Gomes 《Optical Materials》2011,33(12):1902-1906
The authors report the fabrication and characterization of active waveguides in GeO2–PbO–Ga2O3 glass samples doped with Er3+, written with a femtosecond laser delivering pulses of 150 fs duration at 1 kHz repetition rate. Permanent refractive index change was obtained and waveguides were formed under different laser pulse energies and scan velocities. The passive and active optical properties of the waveguides were investigated. The minimum value of propagation loss was of 4.8 dB/cm. Optical amplification at 1.5 μm under 980 nm excitation was observed showing a maximal internal gain of 2.7 dB/cm. 相似文献
39.
de Oliveira Amanda Gerhardt Moreno Janaina Fernandes de Sousa Ana Maria Furtado Esccio Viviane Alves de Oliveira Cavalcanti Guimares Maria Jos da Silva Ana Lucia Nazareth 《Polymer Bulletin》2020,77(6):2889-2904
Polymer Bulletin - Investigating the compatibility mechanism of hybrid composites based on two polymers and one mineral nanofiller is a challenge that needs to be better understood. This study... 相似文献
40.
Maria Elisa Melo Branco de Araújo Yollanda E. Moreira Franco Thiago Grando Alberto Mariana Alves Sobreiro Marco Aurélio Conrado Denise Gonçalves Priolli Alexandra C.H. Frankland Sawaya Ana Lucia T.G. Ruiz João Ernesto de Carvalho Patrícia de Oliveira Carvalho 《Food chemistry》2013
Bioavailability and biological properties of flavonoid glycosides can be improved after the enzymatic hydrolysis of specific glycosyl groups. In this study, we evaluate the antioxidant and antiproliferative potential of rutin after enzymatic hydrolysis performed by α-l-rhamnosidases (hesperidinase from Penicillium sp. and naringinase from Penicillium decumbens) previously heated at 70 °C for 30 min to inactivate the undesirable β-d-glucosidase activity. The highest in vitro antioxidant activity determined by DPPH radical scavenging was achieved with rutin hydrolyzed by hesperidinase. Rutin was predominantly bioconverted into quercetin-3-glucoside. There was no statistical difference between xanthine oxidase inhibition by rutin before and after hydrolysis. However, in vitro inhibitory activity against ten human tumor cell lines showed that hydrolyzed rutin exerted a more potent antiproliferative effect than quercetin and rutin on various cancer cell lines, specially glioma, and ovarian and breast adenocarcinomas. These results indicate that quercetin-3-glucoside could be a promising functional derivative obtained by rutin hydrolysis. 相似文献