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排序方式: 共有1219条查询结果,搜索用时 671 毫秒
51.
Sergio Scognamillo Emilia Gioffredi Massimo Piccinini Massimo Lazzari Valeria Alzari Daniele Nuvoli Roberta Sanna Daniele Piga Giulio Malucelli Alberto Mariani 《Polymer》2012,53(19):4019-4024
Thermoplastic polyurethane (TPU) nanocomposites containing graphene and graphene nanoribbons were obtained by polymerizing 1,4-butanediol with two diisocyanates (namely, 1,6-hexane diisocyanate or isophorone diisocyanate), in which the nanofillers were previously dispersed. Raman spectroscopy and Transmission Electron Microscopy demonstrated the formation of few-layer graphene and graphene nanoribbons dispersed in the monomers. At variance to the methods commonly reported in literature, that used in this work consists of the direct exfoliation of graphite without any chemical manipulation. Apart from the obvious cost and ease advantages, the so-obtained graphene does not contain any carboxy or alkoxy groups formed during the exfoliation process, which, at variance, are typically present in the most commonly reported methods. This finding paves the way toward the large-scale production of graphene and its nanoribbons, which are considered even more interesting than graphene itself for many potential applications. The obtained nanocomposites show a peculiar thermal and rheological behavior due to the presence of the nanofillers and to their reinforcing or plasticizing effect exerted on the TPU matrices. 相似文献
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Béatrice Fuster Deborah Houssin-Agbomson Simon Jallais Elena Vyazmina Guy Dang-Nhu Gilles Bernard-Michel Mike Kuznetsov Vladimir Molkov Boris Chernyavskiy Volodymyr Shentsov Dmitry Makarov Randy Dey Philip Hooker Daniele Baraldi Evelyn Weidner Daniele Melideo Valerio Palmisano Alexandros Venetsanos Jan Der Kinderen 《International Journal of Hydrogen Energy》2017,42(11):7600-7607
Hydrogen energy applications often require that systems are used indoors (e.g., industrial trucks for materials handling in a warehouse facility, fuel cells located in a room, or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons, to isolate them from the end-user and the public, or from weather conditions.Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks, including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture, or can result in jet-fires. Within Hyindoor European Project, carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered: Hydrogen release conditions and accumulation, vented deflagrations, jet fires and including under-ventilated flame regimes (e.g., extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified. 相似文献
54.
Daniele Fanelli 《Scientometrics》2013,95(3):1167-1177
A citation advantage for research covered by the mass media is a plausible, but poorly studied phenomenon. Two previous studies, both conducted in the United States, found a positive correlation between media reporting and citations. Only one of these studies was able to conclude that the correlation was caused by a real “publicity effect” rather than by the media highlighting papers that are intrinsically destined to have greater scientific impact (called the ‘earmark’ hypothesis). This study assessed the relative importance of the publicity effect outside the US, by comparing studies published in 2008 and 2009 in the Proceedings of the National Academy of Sciences that had been featured in newspapers in Italy and the United Kingdom. Newspapers in the two countries covered a similar range of topics, and tended to over-represent local (national) research. Compared to studies not appearing in any of the newspapers considered, those featured in British newspapers had around 63 % more citations, whilst in Italian newspapers 16 %. The proportion of citations from Italian authors, however, was significantly increased by newspapers, particularly by those in Italian. The equivalent effect on citations from the UK was smaller and only marginally significant. Studies accompanied by a press release did not receive, overall, significantly more citations. In sum, results suggest that the publicity effect is strongest for English-speaking media, whilst non-English reporting has mostly a local influence. These effects might represent a confounding factor in citation-based research assessment and might contribute to the many biases known to affect the scientific literature. 相似文献
55.
Daniele Martella Sara Nocentini Dmitry Nuzhdin Camilla Parmeggiani Diederik S. Wiersma 《Advanced materials (Deerfield Beach, Fla.)》2017,29(42)
Grabbing and holding objects at the microscale is a complex function, even for microscopic living animals. Inspired by the hominid‐type hand, a microscopic equivalent able to catch microelements is engineered. This microhand is light sensitive and can be either remotely controlled by optical illumination or can act autonomously and grab small particles on the basis of their optical properties. Since the energy is delivered optically, without the need for wires or batteries, the artificial hand can be shrunk down to the micrometer scale. Soft material is used, in particular, a custom‐made liquid‐crystal network that is patterned by a photolithographic technique. The elastic reshaping properties of this material allow finger movement, using environmental light as the only energy source. The hand can be either controlled externally (via the light field), or else the conditions in which it autonomously grabs a particle in its vicinity can be created. This microrobot has the unique feature that it can distinguish between particles of different colors and gray levels. The realization of this autonomous hand constitutes a crucial element in the development of microscopic creatures that can perform tasks without human intervention and self‐organized automation at the micrometer scale. 相似文献
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57.
Alessandro Gobbi Daniele Manerba Renata Mansini Roberto Zanotti 《International Transactions in Operational Research》2023,30(1):8-38
The average age of the population has grown steadily in recent decades along with the number of people suffering from chronic diseases and asking for treatments. Hospital care is expensive and often unsafe, especially for older individuals. This is particularly true during pandemics as the recent SARS-CoV-2. Hospitalization at home has become a valuable alternative to face efficiently a huge increase in treatment requests while guaranteeing a high quality of service and lower risk to fragile patients. This new model of care requires the redefinition of health services organization and the optimization of scarce resources (e.g., available nurses). In this paper, we study a Nurse Routing Problem that tries to find a good balance between hospital costs reduction and the well-being of patients, also considering realistic operational restrictions like maximum working times for the nurses and possible incompatibilities between services jointly provided to the same patient. We first propose a Mixed Integer Linear Programming formulation for the problem and use some valid inequalities to strengthen it. A simple branch-and-cut algorithm is proposed and validated to derive ground benchmarks. In addition, to efficiently solve the problem, we develop an Adaptive Large Neighborhood Search hybridized with a Kernel Search and validate its performance over a large set of different realistic working scenarios. Computational tests show how our matheuristic approach manages to find good solutions in a reasonable amount of time even in the most difficult settings. Finally, some interesting managerial insights are discussed through an economic analysis of the operating context. 相似文献
58.
Andrey Tverjanovich Evgenii N. Borisov Mohammad Kassem Pascal Masselin Daniele Fontanari Eugene Bychkov 《Journal of the American Ceramic Society》2020,103(5):3070-3075
Frequency conversion using nonlinear optical (NLO) crystals is widely used in advanced photonic technologies to produce coherent light in the spectral regions where the available laser sources are missing. Isotropic glasses usually do not show second order nonlinear processes like second harmonic or difference frequency generation (SHG, DFG) except for temporarily induced anisotropy under external stimuli. Here, we show that a HgI2–Ga2S3–GeS2 homogeneous glass exhibits a strong intrinsic SHG response comparable with that of the well-known NLO single crystal LiNbO3. The origin of this extremely rare phenomenon seems to be noncentrosymmetric bent HgI2 molecules embedded in a sulfide glassy host. Taking into account the unique properties of chalcogenide glasses (wide IR transmission, low phonon density, unlimited ability to be modified changing the appropriate glass properties, fiber drawing and thin layer design), the observed phenomenon opens up the possibility of creating fundamentally new devices for mid-IR photonics. 相似文献
59.
Stefano Piazzi Lorenzo Menin Daniele Antolini Francesco Patuzzi Marco Baratieri 《International Journal of Hydrogen Energy》2021,46(13):8972-8985
This work investigates the opportunity of retrofitting existing small-scale gasifiers shifting from combined heat and power (CHP) to hydrogen and biofuels production, using steam and biomass residues (woodchips, vineyard pruning and bark). The experiments were carried out in a batch reactor at 700 °C and 800 °C and at different steam flow (SF) rates (0.04 g/min and 0.20 g/min). The composition of the producer gas is in the range of 46–70 % H2, 9–29 % CO, 12–27 % CO2, and 2–6 % CH4. A producer gas specific production factor of approx. 10 NLpg/gchar can be achieved when the lower SFs are used, which allows to provide 80 % of the hydrogen concentration required for biomethanation and MeOH synthesis. As for FT synthesis, an optimal H2/CO ratio of approx. 2 can be achieved. The results of this work provide further evidence towards the feasibility of hydrogen and biofuels generation from residual biomass through steam gasification. 相似文献
60.
Daniele da Silva Bastos Maria do Pilar Gonçalves Cristina Tristão de Andrade Kátia Gomes de Lima Araújo Maria Helena Miguez da Rocha Leão 《Food and Bioproducts Processing》2012,90(4):683-692
The aim of this work was to obtain a new stable food product from cashew apple juice encapsulated by spray-drying technique using chitosan–whey protein isolate systems. The materials were evaluated according to their physicochemical stability during storage at different conditions and characterized with respect to their particle size distribution and structure. Encapsulated commercial and natural juices showed homogenous and unimodal particle size distribution with diameters ranging from 0.2 to 5.0 μm and from 0.2 to 40.0 μm, respectively. Both juices demonstrated higher physicochemical stability for vitamin C and color measurements than their respective non-encapsulated juices. X-ray diffractograms evidenced that the powder juices after the 140th day of storage were still in amorphous state. These results indicate that the new product was effective in protecting sensitive compounds present in the food matrix and it was also able to remain stable throughout the study period. 相似文献