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排序方式: 共有930条查询结果,搜索用时 15 毫秒
91.
The paper presents the results of an experimental study on ventilated walls with an external clay cladding in a temperate Mediterranean climate.The aim of this work is to assess the actual thermal performance of the ventilated façade with a complete thermo-fluid dynamic analysis.The paper describes the experimental work carried out on walls with different exposure and various heights of the ventilation channel (6 m and 12 m) with controlled internal air temperature. The air velocities, temperatures and heat fluxes in the ventilated facade were monitored and correlations between the thermo-physical parameters were identified.The study showed that, on sunny days, the external surface temperatures, temperatures in the air cavity and air velocity in the gap are considerably higher for the 12 m wall, while during the nighttime lower temperatures are found for the various layers of the wall.The data obtained allowed us to calculate the Reynolds number and to identify the airflow rate in the channel. Correlations were found between the air velocity in the gap, the airflow rate, the Reynolds number and the sun–air temperature. These correlations are useful for modelling ventilated walls, which are generally very complex, with simplified equivalent walls. Finally it was possible to identify the peak temperatures with respect to exposure and thermal lag. The thermo-graphic analysis showed that the behaviour of the walls is almost uniform without thermal bridges. 相似文献
92.
Rosalbino F Macciò D Giannoni P Quarto R Saccone A 《Journal of materials science. Materials in medicine》2011,22(5):1293-1302
The in vitro corrosion behavior and biocompatibility of two Zr alloys, Zr-2.5Nb, employed for the manufacture of CANDU reactor
pressure tubes, and Zr-1.5Nb-1Ta (at%), for use as implant materials have been assessed and compared with those of Grade 2
Ti, which is known to be a highly compatible metallic biomaterial. The in vitro corrosion resistance was investigated by open
circuit potential and electrochemical impedance spectroscopy (EIS) measurements, as a function of exposure time to an artificial
physiological environment (Ringer’s solution). Open circuit potential values indicated that both the Zr alloys and Grade 2
Ti undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface, in the aggressive
environment. It also indicated that the tendency for the formation of a spontaneous oxide is greater for the Zr-1.5Nb-1Ta
alloy and that this oxide has better corrosion protection characteristics than the ones formed on Grade 2 Ti or on the Zr-2.5Nb
alloy. EIS study showed high impedance values for all samples, increasing with exposure time, indicating an improvement in
corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film presents on the metals
surface, improving their resistance with exposure time, presenting the highest values to the Zr-1.5Nb-1Ta alloy. For the biocompatibility
analysis human osteosarcoma cell line (Saos-2) and human primary bone marrow stromal cells (BMSC) were used. Biocompatibility
tests showed that Saos-2 cells grow rapidly, independently of the surface, due to reduced dependency from matrix deposition
and microenvironment recognition. BMSC instead display a reduced proliferation, possibly caused by a reduced crosstalk with
the metal surface microenvironment. However, once the substrate has been colonized, BMSC seem to respond properly to osteoinduction
stimuli, thus supporting a substantial equivalence in the biocompatibility among the Zr alloys and Grade 2 titanium. In summary,
high in vitro corrosion resistance together with satisfactory biocompatibility make the Zr-2.5Nb and Zr-1.5Nb-1Ta crystalline
alloys promising biomaterials for surgical implants. 相似文献
93.
Mass spectrometry in the diagnosis of thyroid disease and in the study of thyroid hormone metabolism
Marco Borsò Patrizia Agretti Riccardo Zucchi Alessandro Saba 《Mass spectrometry reviews》2022,41(3):443-468
The importance of thyroid hormones in the regulation of development, growth, and energy metabolism is well known. Over the last decades, mass spectrometry has been extensively used to investigate thyroid hormone metabolism and to discover and characterize new molecules involved in thyroid hormones production, such as thyrotropin-releasing hormone. In the earlier period, the quantification methods, usually based on gas chromatography–mass spectrometry, were complicated and time consuming. They were mainly focused on basic research, and were not suitable for clinical diagnostics on a routine basis. The development of the modern mass spectrometers, mainly coupled to liquid chromatography, enabled simpler sample preparation procedures, and the accurate quantification of thyroid hormones, of their precursors, and of their metabolites in biological fluids, tissues, and cells became feasible. Nowadays, molecules of physiological and pathological interest can be assayed also for diagnostic purposes on a routine basis, and mass spectrometry is slowly entering the clinical laboratory. This review takes stock of the advancements in the field of thyroid metabolism that were carried out with mass spectrometry, with special focus on the use of this technique for the quantification of molecules involved in thyroid diseases. 相似文献
94.
Arfni Selene Parandera Lorenzo Botta Gazzaniga Camilla Maggioni Nicolò Tacchino Alessandro 《Minds and Machines》2021,31(1):213-213
Minds and Machines - An amendment to this paper has been published and can be accessed via the original article. 相似文献
95.
Sami Ben-Guedria Brunilde Sansò Jean-François Frigon 《Simulation Modelling Practice and Theory》2011,19(9):2076-2101
In this paper, we present the PolyMAX module which enhances network simulator 2 (ns-2), the most popular network simulator used in academia, to provide one of the most complete simulation tools to evaluate the performance of Mobile WiMAX networks. PolyMAX is based on the National Institute of Standards and Technology (NIST) module and our specific contributions consist on the design and implementation of the Quality of Service (QoS) classes and QoS management messages, the uplink access grant-request mechanisms, Adaptive Modulation and Coding, and a scheduler handling all five WiMAX QoS classes. We also present validation results for the different components of our module and typical WiMAX simulation scenarios illustrating its flexibility and some of its features. The PolyMAX module represents an important tool enabling researchers to easily implement their Mobile WiMAX scheduling and Adaptive Modulation and Coding (AMC) algorithms and accurately evaluate their performance for realistic scenarios. 相似文献
96.
Fàbrega C Andreu T Güell F Prades JD Estradé S Rebled JM Peiró F Morante JR 《Nanotechnology》2011,22(23):235403
Highly ordered TiO(2) nanohole layers were synthesized by anodic oxidation of titanium foils using ethylene glycol and ammonium fluoride as the electrolyte. The effectiveness of different methods, namely annealing at 500?°C in NH(3) and in H(2) diluted in N(2), to incorporate nitrogen into TiO(2) and thus extend its photoelectrochemical (PEC) activity to the visible range was studied. The intra-gap levels introduced by both processes were identified by means of XPS and PL measurements. Water splitting experiments demonstrated that annealing in H(2) improved the photocatalytic activity of pure TiO(2), while annealing in ammonia led to a decrease in the PEC performance. 相似文献
97.
Luciana Lazzeretti Niccolò Innocenti Francesco Capone 《The Annals of Regional Science》2017,58(3):491-512
Cultural and creative industries (CCIs) have recently become highly relevant with regard to creative economy research, as they are considered drivers of regional and urban innovation policies and economic growth. CCIs are a priority sector on the European agenda and represent an excellent opportunity to exit the current economic crisis. In the literature, the most discussed aspect of CCIs is their value creation ability, which is due to a high degree of diversity/variety, and their impact on innovation within the wider economy, which results from the activation of cross-fertilisation processes between different sectors. Evolutionary economic geography (EEG), adopting the recently established approach based on related variety, also emphasises the issues of diversity/variety as determinants of local and urban development and innovation. This interesting and complex theoretical framework has produced a considerable number of empirical studies, none of which has been specifically applied to the creative sector. With the present study, we intended to contribute to the debate on creative economy research and EEG by investigating the impact of variety in CCIs in Italy, following the related-variety approach and using a long-term employment perspective (1991–2011). The results indicated that related variety has an important effect on the growth of creative industries, characterised by high internal connections between different creative activities. Our outcomes also led us to reassess the view held by some, namely, that creative industries can actually make a strong impact on economic growth in the wider economy; this did not appear to emerge in the Italian context, according to the methodologies we used. 相似文献
98.
Patricia Larryoz Margherita Addis Roland Gauch Jacques Olivier Bosset 《International Dairy Journal》2001,11(11-12)
This preliminary study aims to compare two different extraction and concentration methods often used for the gas chromatographic analysis of volatile components in food to determine the advantages and drawbacks of both for future routine investigation of PDO (protected designation origin) ewes’ milk cheeses. Roncal, Pecorino Sardo and Fiore Sardo were investigated at different ripening stages. The dynamic headspace technique using a Purge & Trap device (DHS) makes it possible to extract more highly volatile compounds than the simultaneous distillation extraction (SDE) method. Consequently, the latter is more efficient for extracting low-volatile components such as phenols, free fatty acids, lactones and longer-chain aldehydes, ketones, alcohols and esters. These two extraction methods are therefore complementary. 相似文献
99.
We analyze the classical asset pricing model assuming non fully rationalagents.Agents forecast future prices cum dividend through an adaptive learning rule.This assumption provides an explanation of some anomalies encounteredin the empirical analysis of asset prices under full rationality:returns are serially correlated(positively over a short horizon and negatively over a longer horizon)and the dividend yield predicts future returns (positive correlation).Considering the continuous time limit process,the same regularities are established analytically for price increments. 相似文献
100.
METHODS: We have investigated the effects of allergen immunotherapy on the nasal responses in the guinea-pigs with allergic rhinitis. Thirty-three male Hartley guinea-pigs with allergic rhinitis were divided into three groups; those receiving intradermal injection of saline (Group 1) or 0.1% ovalbumin (Group 2) 6 days after the last intranasal sensitization, and those injected with 0.1% ovalbumin intradermally once daily for 6 consecutive days from the next day after the last intranasal sensitization (Group 3). RESULTS: The dye leakage and histamine content into the nasal lavage significantly decreased at 30 min after antigen challenge in Group 3, compared with Group 1 or 2. We also observed the change of mast cell numbers in superficial nasal mucosa, lamina propria and injected dorsal skin. The number of mast cells in superficial nasal mucosa significantly decreased in Group 3 compared with Group 1 or 2, but not those in nasal lamina propria or dorsal skin. CONCLUSIONS: These results suggest that the improvements of nasal responses such as dye leakage and histamine content may be caused by the decrease of mast cell numbers in the superficial mucosal layer after the specific immunotherapy, which may be developing tolerance and one of the mechanisms underlying the beneficial effect of immunotherapy. 相似文献