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排序方式: 共有2536条查询结果,搜索用时 15 毫秒
991.
Ewa Sawosz S?awomir Jaworski Marta Kutwin Krishna Prasad Vadalasetty Marta Grodzik Mateusz Wierzbicki Natalia Kurantowicz Barbara Strojny Anna Hotowy Ludwika Lipińska Joanna Jagie??o André Chwalibog 《International journal of molecular sciences》2015,16(10):25214-25233
Our previous studies revealed that graphene had anticancer properties in experiments in vitro with glioblastoma multiforme (GBM) cells and in tumors cultured in vivo. We hypothesized that the addition of arginine or proline to graphene solutions might counteract graphene agglomeration and increase the activity of graphene. Experiments were performed in vitro with GBM U87 cells and in vivo with GBM tumors cultured on chicken embryo chorioallantoic membranes. The measurements included cell morphology, mortality, viability, tumor morphology, histology, and gene expression. The cells and tumors were treated with reduced graphene oxide (rGO) and rGO functionalized with arginine (rGO + Arg) or proline (rGO + Pro). The results confirmed the anticancer effect of graphene on GBM cells and tumor tissue. After functionalization with amino acids, nanoparticles were distributed more specifically, and the flakes of graphene were less agglomerated. The molecule of rGO + Arg did not increase the expression of TP53 in comparison to rGO, but did not increase the expression of MDM2 or the MDM2/TP53 ratio in the tumor, suggesting that arginine may block MDM2 expression. The expression of NQO1, known to be a strong protector of p53 protein in tumor tissue, was greatly increased. The results indicate that the complex of rGO + Arg has potential in GBM therapy. 相似文献
992.
The effectiveness of distinct fillers, from micro to nano‐size scaled, on the fire behaviour of an epoxy resin and its carbon fibre reinforced composites was assessed by cone calorimetry. The performance was compared not only regarding the reaction to fire performance, but also in terms of thermal stability, glass transition temperature and microstructure. Regarding the fire reaction behaviour of nanofilled epoxy resin, anionic nanoclays and thermally oxidized carbon nanotubes showed the best results, in agreement with more compact chars formed on the surface of the burning polymer. For carbon fibre reinforced composite plates, the cone calorimeter results of modified resin samples did not show significant improvements on the heat release rate curves. Poorly dispersed fillers in the resin additionally caused reductions on the glass transition temperature of the composite materials. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
993.
Photo‐crosslinked poly(ethylene glycol) diacrylate (PEGDA) hydrogels from low molecular weight prepolymer: Swelling and permeation studies 下载免费PDF全文
Anna Cavallo Marta Madaghiele Ugo Masullo Maria Giulia Lionetto Alessandro Sannino 《应用聚合物科学杂志》2017,134(2)
The aim of this work was to assess the diffusive properties of poly(ethylene glycol) diacrylate (PEGDA)‐based hydrogels, derived from low MW prepolymers, in view of potential biomedical applications. Several hydrogels were synthesized through UV irradiation of PEGDA solutions for different exposure times. Swelling measurements in distilled water were performed to estimate the yielded crosslink density, while swelling tests at 37 °C in selected media allowed to analyze the mesh size changes induced by various pH and ionic strength (IonS) conditions. The transport of glucose and insulin through thin hydrogel membranes was finally assessed in a modified Ussing chamber at physiological values of pH and IonS (7.4 and 150 mM, respectively). Results showed that the swelling was dependent on the IonS (with swelling reductions up to 20–30% for IonS increases in the range 0–300 mM) and, to a lesser extent, on the pH of the surrounding medium (with swelling increments of about 10% for increasing pH in the range 2.5–11). All hydrogels were also permeable to glucose and insulin, which displayed comparable diffusion coefficients (in the order of 10?6 cm2/s). Specific interactions between glucose and the polymer chains were evidenced by values of the partition coefficient higher than unity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44380. 相似文献
994.
From the water-insoluble lipid fraction of the chloroform/methanol/water extract of the gonads and body walls of the Patagonian
starfish Allostichaster inaequalis, two new glucosylceramides (4 and 7) were isolated together with the known phalluside-1 (1) and two glucosylceramides (2 and 3) previously isolated from the starfish Cosmasterias lurida. The new compounds were characterized as (2S,3R,4E,8E,10E)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxy-15-tetracosenoyl] amino-4,8,10-octadecatriene (4) and (2S,3R,4E,15Z)-1-(β-d-glucopyranosyloxy)-3-hydroxy-2-[(R)-2-hydroxyhexadecanoyl] amino-4,15-docosadiene (7) by means of spectroscopic and chemical methods. 相似文献
995.
Elizabeth D. Camarinha Patrícia F. Lito Bruno M. Antunes Marta Otero Zhi Lin Joo Rocha Eduarda Pereira Armando C. Duarte Carlos M. Silva 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,155(1-2):108-114
In this work, the removal of Cd2+ ions from aqueous solution using microporous titanosilicate ETS-10 was investigated in order to assess its potential as decontaminating agent in tertiary treatments. Accordingly, batch stirred tank experiments were carried out to study the ion exchange kinetics and equilibrium. Results show that pH affects considerably the ion exchange capability of ETS-10: at pH 4 it is 1.567 × 102 eq m−3, at pH 6 it is 3.629 × 103, and no further increment was observed at pH 8. This is an extremely important observation since pH of industrial effluents and other wastewaters rounds 6. Both Langmuir and Langmuir–Freundlich isotherms were fitted to the experimental data measured. The second model performs slightly better as the calculated absolute average deviations show: AADL = 2.94% and AADLF = 2.40%. Concerning the kinetic behavior, the ion exchange was successfully represented by a Nernst–Planck based model (AAD = 11.9%). 相似文献
996.
Milk fat is a complex mixture of geometric and positional isomers of monounsaturated and polyunsaturated, including short-,
long- and branch-chain fatty acids (FAs). There has been partial success to resolve this mixture of FAs using different GC
temperature programs, or a combination of GC isothermal and temperature programs. To overcome the problem associated with
overlapping isomers prior silver-ion separation was recommended. However, this procedure is time consuming and not practical
for routine analysis. In addition, previous methods focused mainly on the trans and cis isomers of 18:1. The present method takes advantage of differences in the relative elution times between different types
of FAs. The method involved analyzing each milk fat using the same highly polar 100-m capillary column and GC instrument,
and conducting two separations using temperature programs that plateau at 175 and 150 °C. The relative shift among the geometric
and positional isomers at these two temperature settings was enough to permit identification of most of the trans and cis 16:1, 18:1 and 20:1, the c/t-18:2 and the c/c/t-18:3 isomers found in milk fat. The identity of these FAs was confirmed by prior separation of the total fatty acid methyl
esters (FAMEs) of milk fat using Ag+-SPE columns, and comparing the fractions to the total milk fat. The Ag+-SPE technique was modified to obtain pure saturated, trans- and cis-monounsaturated and diunsaturated FAMEs. By combining the results from these two separate GC analyses, knowing the elution
order, it was possible to determine most of the geometric and positional isomers of 16:1, 18:1, 20:1, 18:2 and 18:3 without
a prior silver-ion separation. Only few minor FAs could not be resolved, notable the conjugated linoleic acid isomers that
still required the complimentary Ag+-HPLC separation. The two GC temperature programs have been successfully used to routinely analyze most FA isomers in total
milk and beef fats in about 200 min without the use of prior silver-ion separations. 相似文献
997.
998.
Marta Harničárová Jan Valíček Robert Čep Hakan Tozan Jana Müllerová Radovan Grznárik 《The International Journal of Advanced Manufacturing Technology》2013,69(1-4):81-91
The contribution deals with comparing non-traditional cutting technologies from the point of view of generated surface roughness. The comparison is carried out for technologies of abrasive waterjet cutting, oxygen cutting, laser and plasma cutting. As an experimental material, EN S355J0 structural steel and titanium CP-Ti Grade 2 was used. Surface topography measurement was done using a Mitutoyo Surftest SJ-401 instrument, and an optical profilometer MicroProf FRT was used for comparison and verification of acquired surface data. The aim of the contribution is to clarify, on the basis of experimental measurements, the behaviour of a topographic function after various ways of cutting; the knowledge of the function is necessary for solving both theoretical and practical technological tasks. The topographic function, which is a basis for the prediction of quality and control of the cutting processes, was derived in an original way. The use of individual technologies depends on technical and economical possibilities and on environmental influences. The results of measurement of cut surface roughness are in good accordance with the results of theoretical analysis. 相似文献
999.
Leandro Maia Fernanda C. Landim‐Alvarenga Ligia S. L. Silveira Da Mota Marjorie De Assis Golim Reneé Laufer‐Amorim Bruna De Vita Danielle Jaqueta Barberini Amanda Jeronimo Listoni Carolina Nogueira De Moraes Marta Cristina Thomas Heckler Rogério Martins Amorim 《Microscopy research and technique》2013,76(6):618-624
The aim of this study was to isolate, culture, and characterize mesenchymal stem cells (MSCs) from horse bone marrow (BM) using the techniques of flow cytometry, immunocytochemistry, cytogenetics, and electron microscopy. Immunophenotypic analysis revealed the presence of MSCs with high expression of the CD90 marker, lower expression of the CD44 marker, and absent expression of the CD34 marker. In assays of differentiation, the positive response to osteogenic (OST), chondrogenic (CDG), and adipogenic (ADP) differentiation signals was observed and characterized by deposition of calcium‐rich extracellular matrix (OST), proteoglycans and collagen II (CDG) and intracellular deposition of fat drops (ADP). In immunocytochemical characterization, MSCs were immunopositive for CD44, vimentin, and PCNA, and they were negative for CD13. In the ultrastructural analysis of MSCs, the most outstanding characteristic was the presence of rough endoplasmic reticulum with very dilated cisterns filled with a low electrodensity material. Additionally, MSCs had normal karyotypes (2n = 64) as evidenced by cytogenetic analysis, and aneuploidy in metaphase was not observed. The protocols for isolating, culturing, and characterizing equine MSCs used in this study were shown to be appropriate for the production of a cell population with a good potential for differentiation and without aneuploidy that can be used to study future cellular therapies. Microsc. Res. Tech. 76:618–624, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
1000.
Alexandra Muñoz-Bonilla Marta Fernández-GarcíaJuan Rodríguez-Hernández 《Progress in Polymer Science》2014
This article reviews the approaches developed to prepare and characterize porous structured materials by using the breath figures (BF) methodology. In particular, we have analyzed the topographical modifications of the surface that can be tuned with this approach, such as the control of the pore characteristics, changes in the pore morphology or use of non-planar substrates to create the porous materials among others. We have also given special attention to the functionality inside of the pores and how this can be created by using different kinds of polymers, from homopolymers to hybrid materials, as well as by changing the pore functionally after chemical modification. The approaches followed to obtain hierarchical structures, for example, by combination of the BF approach and nanostructure formation within the pores or by using soft-lithography have also been examined. In addition, we discuss the feasibility of obtaining stimuli-responsive honeycomb structured surfaces. The potential applications in different areas such as biomedicine, optics and so on, are also pointed out. Finally, we comment on some future perspectives of breath figures approach. 相似文献