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991.
G Lupoli C Di Carlo V Nuzzo G Vitale D Russo S Palomba C Nappi 《Canadian Metallurgical Quarterly》1997,20(8):493-496
Women with amenorrhea and polycystic ovaries (PCO) seem to present a relative degree of protection against bone loss caused by hypoestrogenism. We treated 20 patients affected by polycystic ovary syndrome (PCOS) with a gonadotropin-releasing hormone agonist (GnRH-a) for 6 months. After treatment mean bone mineral density (BMD) significantly decreased. We concluded that patients with PCOS have to be considered at risk of developing osteopenia when treated with GnRH-a. The relative protection against osteoporosis, that is present in amenorrheic patients with PCO, might be attributed to the characteristics of amenorrhea in these patients. 相似文献
992.
Massimiliano Pieraccini Filippo Parrini Devis Dei Matteo Fratini Carlo Atzeni Paolo Spinelli 《NDT & E International》2007,40(5):390-396
The dynamic characterization of a medieval bell tower, forced by its own bell is obtained by using a newly developed interferometric sensor. The displacement of the tower is remotely detected, without installation of contact sensors and the use of a cumbersome vibrodyne for structure excitation. The measurement technique demonstrated in this paper allows heritage bell towers to be monitored in a simple and rapid way. 相似文献
993.
Functionalized Graphene as an Electron‐Cascade Acceptor for Air‐Processed Organic Ternary Solar Cells 下载免费PDF全文
Francesco Bonaccorso Nikolaos Balis Minas M. Stylianakis Marika Savarese Carlo Adamo Mauro Gemmi Vittorio Pellegrini Emmanuel Stratakis Emmanuel Kymakis 《Advanced functional materials》2015,25(25):3870-3880
Functionalized graphene nanoflakes (GNFs) are used as an electron‐cascade acceptor material in air‐processed organic ternary bulk heterojunction solar cells. The functionalization is realized via the attachment of the ethylenedinitrobenzoyl (EDNB) molecule to the GNFs. Simulation and experimental results show that such nanoscale modification greatly influences the density of states near the Fermi level. Consequently, the GNF‐EDNB blend presents favorable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels to function as a bridge structure between the poly[N‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′‐benzothiadiazole)] (PCDTBT) and the [6,6]‐phenyl‐C71‐butyric‐acid‐methyl‐ester (PC71BM). The improved exciton dissociation and charge transport are associated with the better energy level alignment of the ternary blend and the high electrical conductivity of the GNFs, which act as additional electron transport channels within the photoactive layer. The resulting PCDTBT/GNF‐EDNB/PC71BM ternary organic solar cells, fabricated entirely under ambient conditions, exhibit an average power conversion efficiency enhancement of ≈18% as compared with the binary blend PCDTBT/PC71BM. 相似文献
994.
995.
Jenny Wooldridge Mark Stewart Carlo Vecchini Markys G. Cain Matthias Gutmann Mike Reece 《Journal of the American Ceramic Society》2014,97(7):2111-2115
Single crystal (1 ? x)Pb(Mg1/3 Nb2/3)O3–xPbTiO3 [PMN–xPT] (x = 0.32) is a relaxor‐ferroelectric material known to exhibit ‘giant’ piezoelectric behavior, with achievable strains in excess of 1% for samples of certain particular crystallographic orientations and chemical compositions close to the morphotropic phase boundary. In this study, we investigate the electric field‐induced structural phase transitions in single crystal PMN–0.32PT with time‐of‐flight neutron diffraction and macroscopic electrical polarization measurements, and show that both the frequency of the applied ac field and the temperature of the sample are critical factors in determining these phase transition fields. 相似文献
996.
Molecular‐Level Switching of Polymer/Nanocrystal Non‐Covalent Interactions and Application in Hybrid Solar Cells 下载免费PDF全文
Carlo Giansante Rosanna Mastria Giovanni Lerario Luca Moretti Ilka Kriegel Francesco Scotognella Guglielmo Lanzani Sonia Carallo Marco Esposito Mariano Biasiucci Aurora Rizzo Giuseppe Gigli 《Advanced functional materials》2015,25(1):111-119
Hybrid composites obtained upon blending conjugated polymers and colloidal semiconductor nanocrystals are regarded as attractive photoactive materials for optoelectronic applications. Here it is demonstrated that tailoring nanocrystal surface chemistry permits to control non‐covalent and electronic interactions between organic and inorganic components. The pending moieties of organic ligands at the nanocrystal surface are shown to not merely confer colloidal stability while hindering charge separation and transport, but drastically impact morphology of hybrid composites during formation from blend solutions. The relevance of this approach to photovoltaic applications is demonstrated for composites based on poly(3‐hexylthiophene) and lead sulfide nanocrystals, considered as inadequate until this report, which enable the fabrication of hybrid solar cells displaying a power conversion efficiency that reaches 3%. By investigating (quasi)steady‐state and time‐resolved photo‐induced processes in the nanocomposites and their constituents, it is ascertained that electron transfer occurs at the hybrid interface yielding long‐lived separated charge carriers, whereas interfacial hole transfer appears hindered. Here a reliable alternative aiming to gain control over macroscopic optoelectronic properties of polymer/nanocrystal composites by mediating their non‐covalent interactions via ligands' pending moieties is provided, thus opening new possibilities towards efficient solution‐processed hybrid solar cells. 相似文献
997.
Effect of Heat Treatment and of Primary Austenite Grain Size on the Minimum Size of Detectable Defect on 26NiCrMoV11.5 High Strength Steel 下载免费PDF全文
998.
Franco Concli Carlo Gorla Augusto Della Torre Gianluca Montenegro 《Lubrication Science》2015,27(5):313-326
The increasing need of more and more efficient gearboxes implies the need of predictive models in order to compare, during the design stage, different design solutions. The models provided by literature are mostly experimentally derived and not accurate on real applications. A new trend suggests the adoption of computational fluid dynamics (CFD) for the calculation of the no‐load losses of gear transmissions. In this sense, literature provides some works, but most of them involve only one single phase. In this paper, the real operating condition in which the gears are immersed in an oil lubricant mixture is studied. Adopting an open‐source code, OpenFOAM®, the influence of some operating and geometrical parameters on the churning losses has been investigated. The aims are both to provide data that can be effectively used by engineers in the design practice and to prove, once again, CFD to be an effective approach for this kind of investigations. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
999.
1000.
Frequency Parameters of the Myoelectric Signal as a Measure of Muscle Conduction Velocity 总被引:16,自引:0,他引:16
Dunrng a sustained muscle contraction, the spectrum of the myoelectric signal is known to undergo compression as a function of time. Previous investigators have shown that the frequency compression is related to the decreasing conduction velocity of the muscle fibers. It is proposed that the frequency compression may be tracked by obtaining a continuous estimate of a characteristic frequency of the spectrum, such as the mean and median, or the ratio of low-frequency components to high-frequency components of the spectrum. A theoretical analysis was performed to investigate the restrictions in estimating the three parameters, as well as their sensitivity to the conduction velocity. The ratio parameter was found to be most sensitive to conduction velocity, but was the least reliable of the three. The median frequency was the least sensitive to noise. Therefore, from a theoretical point of view, the median frequency is the preferred parameter. A technique is described which determines an unbiased consistent estimate of the median frequency. The technique may be readily implemented in analog hardware. 相似文献