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71.
Biocompatible and biodegradable alginate/poly(N‐isopropylacrylamide) hydrogels for sustained theophylline release 下载免费PDF全文
Raluca Petronela Dumitriu Ana‐Maria Oprea Catalina Natalia Cheaburu Manuela‐Tatiana Nistor Ovidiu Novac Cristina Mihaela Ghiciuc Lenuta Profire Cornelia Vasile 《应用聚合物科学杂志》2014,131(17)
Mixed‐interpenetrated polymeric networks based on sodium alginate (ALG) and poly(N‐isopropylacryl amide) (PNIPAAm) covalently cross‐linked with N,N'‐methylenebisacrylamide are studied for their biocompatibility, nontoxicity, and biodegradability aiming their application in drug delivery. The presence of drug‐polymeric matrix interactions and the distribution of the drug in the polymeric network for theophylline‐loaded ALG/PNIPAAm hydrogels are also investigated by spectroscopic and microscopic methods. The quantitative evaluation of theophylline loaded hydrogels performed by NIR‐CI technique shows a better drug entrapment and a higher homogeneity of the samples with increased alginate content. The thermal behavior of the hydrogels is significantly modified by theophylline presence. The application of the ALG/PNIPAAm hydrogels as carriers for sustained drug release formulations was assessed by the theophylline release tests performed both by in vitro and in vivo studies. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40733. 相似文献
72.
Indium–tin oxide nanowires were deposited by excimer laser ablation onto catalyst-free oxidized silicon substrates at a low
temperature of 500 °C in a nitrogen atmosphere. The nanowires have branches with spheres at the tips, indicating a vapor–liquid–solid
(VLS) growth. The deposition time and pressure have a strong influence on the areal density and length of the nanowires. At
the earlier stages of growth, lower pressures promote a larger number of nucleation centers. With the increase in deposition
time, both the number and length of the wires increase up to an areal density of about 70 wires/μm2. After this point all the material arriving at the substrate is used for lengthening the existing wires and their branches.
The nanowires present the single-crystalline cubic bixbyite structure of indium oxide, oriented in the 〈100〉 direction. These
structures have potential applications in electrical and optical nanoscale devices. 相似文献
73.
Al-Zandi Muaiyd H. M. Wang Changhai Voicu Rodica Muller Raluca 《Microsystem Technologies》2018,24(1):379-387
Microsystem Technologies - This paper presents our work on measurement and characterization of electrothermal microgrippers for micromanipulation and microassembly applications. The SU-8 based... 相似文献
74.
75.
Mihaela Mindroiu Raluca Ion Cristian Pirvu Anisoara Cimpean 《Materials science & engineering. C, Materials for biological applications》2013,33(6):3353-3361
In this study, polypyrrole (PPy) films were successfully synthesized on Ti6Al7Nb alloy by potentiostatic polymerization in the presence of poly(sodium 4-styrenesulfonate) (NaPSS), t-octylphenoxy polyethoxyethanol (Triton X-100) and N-dodecyl-β-D-maltoside (DM) surfactants. Atomic force microscopy (AFM) analysis of the PPy/surfactant composite films revealed a granular structure characterized by a lower surface roughness than un-modified PPy films. The results demonstrated that addition of surfactants, namely Triton X-100 and DM, can improve electrochemical film stability and corrosion resistance. Further, Triton X-100 enhanced the adhesive strength of PPy films to the substrate. The surfactant type also showed a great influence on the surface wettability, the highest hydrophilic character being observed in the case of PPy/PSS film. Few studies have been devoted to the elucidation of inflammatory cell response to PPy-based materials. Therefore, RAW 264.7 macrophages were cultured on PPy-surfactant films to determine whether they elicit a differential cell behavior in terms of cell adhesion, proliferation, cellular morphology and cytokine secretion. Our results highlight the dependence of macrophage response on the surfactants used in the pyrrole polymerization process and suggest that the immune response to biomaterials coated with PPy films might be controlled by the choice of surfactant molecules. 相似文献
76.
Viorel Sandu Gheorghe Aldica Raluca Damian Zhi-Chao Guo Hong-Li Suo 《Journal of Superconductivity and Novel Magnetism》2013,26(2):361-369
We have studied the one-step procedure for simultaneous synthesis and sintering of SiC-doped MgB2 by the spark plasma sintering technique. Two types of composition, one in which Mg is strongly deficient, with the atomic ratio $\mathrm{B/Mg} = 3.75$ , and one in which Mg content is slightly higher than the stoichiometric value, specifically $\mathrm{B/Mg} = 1.87$ , were investigated. The amount of SiC was 12 wt.% and 9 wt.%, respectively. For comparison we also studied the way the deficit of Mg can be compensated in a second process of sintering. The sample with Mg deficit shows that SiC is left almost unreacted but the results are spectacular: the highest critical temperature, 36.5 K, the highest upper critical field and the highest self-field critical current density 6.7×105 A/cm2 at 10 K. In the sample with overstoichiometric Mg, SiC is decomposed, carbon diffuses within MgB2 but the critical temperature is only of 35.8 K and the zero-field critical current density is one order of magnitude lower. The compensation of the deficit of Mg in the two-step procedure is not efficient. The critical temperature is even lower, 35.8 K, the upper critical field is also lower despite SiC decomposition and C diffusion within MgB2 and the critical current density is slightly above 105 A/cm2. However, at low temperatures and fields of order 7 T the sample with overstoichiometric Mg and the sample prepared by the two-step procedure have higher critical current density. 相似文献
77.
Raluca Marinica Albu Ecaterina Avram Iuliana Stoica Emil Ghiocel Ioanid Silvia Ioan 《Polymer Composites》2011,32(10):1661-1670
Quaternized polysulfones were synthesized by the quaternization reaction of chloromethylated polysulfone with different tertiary amines −N,N‐dimethylethylamine (DMEA) and N,N‐dimethyloctylamine (DMOA), respectively. New blends from these quaternized polysulfones (PSF‐DMEA or PSF‐DMOA) with polystyrene (PS) or poly(4‐vinylpyridine) (P4VP) were prepared by the solution casting method. Pure quaternized polysulfones, in N,N‐dimethylformamide (DMF)/methanol (MeOH) and DMF/water solvent/nonsolvent mixtures, and their blends with PS and P4VP, as well, were investigated by shear viscometry and viscoelasticity, atomic force microscopy, differential scanning calorimetry, and surface properties. The results obtained revealed that the blends have good miscibility. Surface morphology is characterized by roughness and nodules formations, depending on the alkyl radical lengths, composition of the polymer mixtures, including specific electron‐donor or electron‐acceptor characteristics of polymers. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers 相似文献
78.
Stephan Bosch Raluca Marin-Perianu Paul Havinga Arie Horst Mihai Marin-Perianu Andrei Vasilescu 《Personal and Ubiquitous Computing》2012,16(7):875-895
An essential component in the ubiquitous computing vision is the ability of detecting with which objects the user is interacting during his or her activities. We explore in this paper a solution to this problem based on wireless motion and orientation sensors (accelerometer and compass) worn by the user and attached to objects. We evaluate the performance in realistic conditions, characterized by limited hardware resources, measurement noise due to motion artifacts and unreliable wireless communication. We describe the complete solution, from the theoretical design, going through simulation and tuning, to the full implementation and testing on wireless sensor nodes. The implementation on sensor nodes is lightweight, with low communication bandwidth and processing needs. Compared to existing work, our approach achieves better performance (higher detection accuracy and faster response times), while being much more computationally efficient. The potential of the concept is further illustrated by means of an interactive multi-user game. We also provide a thorough discussion of the advantages, limitations and trade-offs of the proposed solution. 相似文献
79.
Oana Maria Păduraru Diana Ciolacu Raluca Nicoleta Darie Cornelia Vasile 《Materials science & engineering. C, Materials for biological applications》2012,32(8):2508-2515
Novel physically cross-linked cryogels containing polyvinyl alcohol (PVA) and various amounts of microcrystalline cellulose were obtained by freezing/thawing technique. The main goal of this study was to improve the properties and the performances of the pure PVA cryogels. The morphological aspects of the cryogels were studied by scanning electron microscopy (SEM). The Fourier transform infrared spectroscopy (FT-IR) was used to reveal the presence of the interactions between the two polymers. Changes in crystallinity of the samples were confirmed by X-ray diffraction (XRD) and by FT-IR spectroscopy. The modification of the thermal behavior induced by cellulose was studied by thermogravimetry. Rheological analysis revealed higher values of storage modulus (G′) for the cryogels containing higher amounts of cellulose. The degree and rate of swelling were controlled by the presence of the natural polymer in the network. The potential application as bioactive compound carriers was tested, using vanillin as an active agent. 相似文献
80.
Raluca FrunzaDan Ricinschi Felicia Gheorghiu Radu ApetreiDumitru Luca Liliana MitoseriuMasanori Okuyama 《Journal of Alloys and Compounds》2011,509(21):6242-6246
Stoichiometric films were prepared by rf-magnetron sputtering from a Pb(Zr0.54Ti0.46)O3 ceramic target onto Au-electroded substrates of alumina. During deposition the substrate holder was kept at a temperature of 300 °C. Post-deposition heat treatment in air at 650 °C was carried to promote the full crystallization and to result in pure perovskite PZT phase. SEM-EDX measurements for the films were performed both on surface and on cross-section. The impedance spectroscopy data demonstrates that the films have rather good dielectric properties and low losses. The recorded P-E loops prove their macroscopic ferroelectric characteristics, while piezoresponse force microscopy experiments confirm a nanoscale switching mechanism based on domain nucleation-growth. 相似文献