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排序方式: 共有453条查询结果,搜索用时 31 毫秒
51.
Immacolata Ruggiero Monica Terracciano Nicola M Martucci Luca De Stefano Nunzia Migliaccio Rosarita Tatè Ivo Rendina Paolo Arcari Annalisa Lamberti Ilaria Rea 《Nanoscale research letters》2014,9(1):329
Diatomite is a natural fossil material of sedimentary origin, constituted by fragments of diatom siliceous skeletons. In this preliminary work, the properties of diatomite nanoparticles as potential system for the delivery of drugs in cancer cells were exploited. A purification procedure, based on thermal treatments in strong acid solutions, was used to remove inorganic and organic impurities from diatomite and to make them a safe material for medical applications. The micrometric diatomite powder was reduced in nanoparticles by mechanical crushing, sonication, and filtering. Morphological analysis performed by dynamic light scattering and transmission electron microscopy reveals a particles size included between 100 and 300 nm. Diatomite nanoparticles were functionalized by 3-aminopropyltriethoxysilane and labeled by tetramethylrhodamine isothiocyanate. Different concentrations of chemically modified nanoparticles were incubated with cancer cells and confocal microscopy was performed. Imaging analysis showed an efficient cellular uptake and homogeneous distribution of nanoparticles in cytoplasm and nucleus, thus suggesting their potentiality as nanocarriers for drug delivery.
PACS
87.85.J81.05.Rm; 61.46. + w 相似文献52.
53.
Ilaria Cristofolini Alberto Molinari Giovanni Straffelini Palloma Vieira Muterlle 《Materials & Design》2011
Aim of this work is proposing a systematic design approach for wear resistant components produced by Powder Metallurgy (PM). Wear is a cause of failure for many industrial PM parts. Gears and cams, for example, are subjected to rolling and rolling–sliding wear, dry or lubricated depending on the applications. The design criteria are mostly empirical, thus resulting fully conservative, sometimes excessively conservative. A need for defining design criteria for wear resistant PM parts is thus revealed, to exploit at best the specific characteristics of both technology and materials. 相似文献
54.
Fortunati E Latterini L Rinaldi S Kenny JM Armentano I 《Journal of materials science. Materials in medicine》2011,22(12):2735-2744
New nanocomposite films based on a biodegradable poly (DL-Lactide-co-Glycolide) copolymer (PLGA) and different concentration
of silver nanoparticles (Ag) were developed by solvent casting. In vitro degradation studies of PLGA/Ag nanocomposites were
conducted under physiological conditions, over a 5 week period, and compared to the behaviour of the neat polymer. Furthermore
the silver ions (Ag+) release upon degradation was monitored to obtain information on the properties of the nanocomposites during the incubation.
The obtained results suggest that the PLGA film morphology can be modified introducing a small percentage of silver nanoparticles
that do not affect the degradation mechanism of PLGA polymer in the nanocomposite. However results clearly evinced the stabilizing
effect of the Ag nanoparticles in the PLGA polymer and the mineralization process induced by the combined effect of silver
and nanocomposite surface topography. The Ag+ release can be controlled by the polymer degradation processes, evidencing a prolonged antibacterial effect. 相似文献
55.
Raffaele Landolfo Lucrezia Cascini Francesco Portioli 《Frontiers of Architecture and Civil Engineering in China》2011,5(3):304-314
Nowadays, the construction sector is more and more oriented toward the promotion of sustainability in all its activities.
The goal to achieve is the optimization of performances, over the whole life-cycle, with respect to environmental, economic
and social requirements. According to the latest advances, the concept of sustainability applied to constructions covers a
number of branches such as life-cycle costing, ecology, durability and even structural design. Several procedures and design
tools have been implemented in the framework of international research. Indeed the current trend in civil engineering research
is moving towards life-time engineering, with the aim to implement integrated methodologies to consider as a whole all the
sustainability requirements according to time-dependent multi-performance-based design approaches. Following a general introduction
of the concept of sustainability applied to constructions, this paper presents an overview of life-time engineering methodologies
according to the current state-of-the-art. In particular the methods currently received by International Standards are discussed.
A special focus is devoted to the durability design of metal structures with respect to the degradation phenomena able to
impair the structural capacity over time. Finally a proposal towards an integrated approach to life-time engineering design
of steel structures and needs for further advances are presented. 相似文献
56.
Rosso Ilaria Antonini Massimiliano Galletti Camilla Saracco Guido Specchia Vito 《Topics in Catalysis》2004,30(1-4):475-480
Topics in Catalysis - Ru-based catalysts supported on A zeolites and alumina were synthesised, characterised (XRD, SEM-EDS, TPR) and tested under realistic conditions for the preferential oxidation... 相似文献
57.
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59.
Sulfolobus solfataricus protein disulphide oxidoreductase: insight into the roles of its redox sites
Limauro D Saviano M Galdi I Rossi M Bartolucci S Pedone E 《Protein engineering, design & selection : PEDS》2009,22(1):19-26
Sulfolobus solfataricus protein disulphide oxidoreductase (SsPDO)contains three disulphide bridges linking residues C41XXC44,C155XXC158, C173XXXXC178. To get information on the role playedby these cross-links in determining the structural and functionalproperties of the protein, we performed site-directed mutagenesison Cys residues and investigated the changes in folding, stabilityand functional features of the mutants and analysed the resultswith computational analysis. The reductase activity of SsPDOand its mutants was evaluated by insulin and thioredoxin reductaseassays also coupled with peroxiredoxin Bcp1 of S. solfataricus.The three-dimensional model of SsPDO was constructed and correlatedwith circular dichroism data and functional results. Biochemicalanalysis indicated a key function for the redox site constitutedby Cys155 and Cys158. To discriminate between the role of thetwo cysteine residues, each cysteine was mutagenised and thebehaviour of the single mutants was investigated elucidatingthe basis of the electron-shuffling mechanism for SsPDO. Finally,cysteine pK values were calculated and the accessible surfacefor the cysteine side chains in the reduced form was measured,showing higher reactivity and solvent exposure for Cys155. 相似文献
60.
Carpinella I Cattaneo D Bertoni R Ferrarin M 《IEEE transactions on neural systems and rehabilitation engineering》2012,20(3):351-360
In this pilot study, we compared two protocols for robot-based rehabilitation of upper limb in multiple sclerosis (MS): a protocol involving reaching tasks (RT) requiring arm transport only and a protocol requiring both objects' reaching and manipulation (RMT). Twenty-two MS subjects were assigned to RT or RMT group. Both protocols consisted of eight sessions. During RT training, subjects moved the handle of a planar robotic manipulandum toward circular targets displayed on a screen. RMT protocol required patients to reach and manipulate real objects, by moving the robotic arm equipped with a handle which left the hand free for distal tasks. In both trainings, the robot generated resistive and perturbing forces. Subjects were evaluated with clinical and instrumental tests. The results confirmed that MS patients maintained the ability to adapt to the robot-generated forces and that the rate of motor learning increased across sessions. Robot-therapy significantly reduced arm tremor and improved arm kinematics and functional ability. Compared to RT, RMT protocol induced a significantly larger improvement in movements involving grasp (improvement in Grasp ARAT sub-score: RMT 77.4%, RT 29.5%, p=0.035) but not precision grip. Future studies are needed to evaluate if longer trainings and the use of robotic handles would significantly improve also fine manipulation. 相似文献