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排序方式: 共有194条查询结果,搜索用时 593 毫秒
171.
Antonello Astarita Mario Coppola Sergio Esposito Mariacira Liberini Leandro Maio Ilaria Papa Fabio Scherillo Antonino Squillace 《先进制造进展(英文版)》2016,4(4):305-313
Linear friction welding (LFW) is an innovative solid-state welding technique that allows to manufacture joints with high mechanical properties. This technology has various applications in the aerospace field; in particular it is used to weld massive structural components made of Ti6Al4V. This paper deals with the experimental study of Ti6Al4V T-joints welded through LFW, with particular focus on the effectiveness of ultrasonic control in detecting and distinguishing welding defects within the joints. Aiming to this scope, joints with different properties were manufactured and tested:some were free from defects but with different metallurgy, and some had different types of defects. The results obtained proved that the ultrasonic control was an effective method to detect and identify defects in linear friction welded titanium joints, moreover it was possible to get information regarding the microstructure and in particular the extension of the different metallurgical zones induced by the welding process. 相似文献
172.
Sara Comini Rosaria Sparti Bartolomeo Coppola Mehdi Mohammadi Sara Scutera Francesca Menotti Giuliana Banche Anna Maria Cuffini Paola Palmero Valeria Allizond 《International journal of molecular sciences》2021,22(18)
In this study, we designed and developed novel poly(ε-caprolactone) (PCL)-based biomaterials, for use as bone scaffolds, through modification with both biphasic calcium phosphate (BCP), to impart bioactive/bioresorbable properties, and with silver nitrate, to provide antibacterial protection against Staphylococcus aureus, a microorganism involved in prosthetic joint infections (PJIs). Field emission scanning electron microscopy (FESEM) showed that the samples were characterized by square-shaped macropores, and energy dispersive X-ray spectroscopy analysis confirmed the presence of PCL and BCP phases, while inductively coupled plasma–mass spectrometry (ICP–MS) established the release of Ag+ in the medium (~0.15–0.8 wt% of initial Ag content). Adhesion assays revealed a significant (p < 0.0001) reduction in both adherent and planktonic staphylococci on the Ag-functionalized biomaterials, and the presence of an inhibition halo confirmed Ag release from enriched samples. To assess the potential outcome in promoting bone integration, preliminary tests on sarcoma osteogenic-2 (Saos-2) cells indicated PCL and BCP/PCL biocompatibility, but a reduction in viability was observed for Ag-added biomaterials. Due to their combined biodegrading and antimicrobial properties, the silver-enriched BCP/PCL-based scaffolds showed good potential for engineering of bone tissue and for reducing PJIs as a microbial anti-adhesive tool used in the delivery of targeted antimicrobial molecules, even if the amount of silver needs to be tuned to improve osteointegration. 相似文献
173.
Harrison Emily L. R.; Coppola Sabrina; McKee Sherry A. 《Canadian Metallurgical Quarterly》2009,17(2):91
Increased nicotine deprivation and impulsivity have been associated with relapse but the degree to which they together influence cognitive processing has not been explored. We examined the effects of increasing levels of nicotine deprivation on cognitive processing, and assessed the relationship of trait impulsivity with these effects in daily smokers (n = 30). Using a within-subject design with three deprivation conditions (nondeprived, 5-hr, 17-hr), volunteers completed the Conners' Continuous Performance Task-II and the Cued Go/No-Go Task. Trait impulsivity was assessed at intake with the Barratt Impulsiveness Scale (Patton et al., 1995). Mixed-model regression analyses revealed deprivation slowed reaction time, increased errors, increased variability in responding, and increased failures of inhibitory control. Performance at 17 hours of deprivation was most likely to be affected. Significant deprivation and impulsivity interactions indicated impulsiveness was negatively correlated with deprivation-associated performance decrements. Less impulsive smokers were more affected by deprivation, demonstrating greater impairment. Research is needed to understand mechanisms by which impulsivity confers greater risk for relapse. Our results suggest deprivation may not increase relapse risk among impulsive smokers by increasing impairment of cognitive processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
174.
In this work the authors extend the high order compact difference schemes to the matching technique to develop a Local Matched Reconstruction theory that can be also considered as a generalization of the spline theory. The problem of the high order reconstructions correlated to an optimal matching in overlapping regions for contiguous expansions in one or more dimensions is stressed; some new generalized matched interpolations and their related numerical schemes are presented together with Fourier analysis of errors. Finally, some relevant aspects of the computational efforts associated to the various approaches are discussed. 相似文献
175.
The effect of the addition of 0.1M LiBr to dimethylformamide (DMF) solutions of charged and uncharged polymers has been studied by GPC and [η] measurements. LiBr has a salting-out effect on polyacrylonitrile (with (PAN-S) and without (PAN) sulfonate sulfur), polystyrene (PS), and poly(vinyl acetate) (PVAc), which is seen by a decrease in [η] and an increase in the GPC retention time. The increase in retention time is, however, abnormally high for charged polymers. Association in PAN and PAN-S solutions in DMF can explain the experimental observations. 相似文献
176.
Electrochemical gas absorption or biotechnical purification processes using structured packing as electrode or as biological support, respectively, may operate in bubble columns in presence of suspended solids. In both systems the knowledge of mass transfer rates from the liquid to the packing is important for the design of equipment. In the present investigation, the fluid dynamic behavior of a simple bubble column and a bubble column containing small size particles, both in presence of structured packing, was studied. Furthermore, mass transfer coefficients between the liquid and the structured packing were obtained by the electrochemical method. The influence of physical properties of the liquid phase, gas flow rate, kind and concentration of the suspended particles on both gas holdup and mass transfer was investigated. Correlations of the experimental data of mass transfer using dimensionless groups were derived and compared to previous correlations. Similarity with a heat transfer expression already used in two-phase systems was found. 相似文献
177.
Pepe O Villani F Oliviero D Greco T Coppola S 《International journal of food microbiology》2003,84(3):319-326
Lactic acid bacteria (LAB) and yeasts were selected on the basis of in vitro proteolytic activity against wheat gluten protein and then assayed as leavening agents for pizza dough. Trials were carried out to compare a proteolytic starter (Prt(+)), consisting of Lactobacillus sakei T56, Weissella paramesenteroides A51 and Candida krusei G271, and a non-proteolytic starter (Prt(-)), consisting of Lb. sakei T58, W. paramesenteroides A58 and Saccharomyces cerevisiae T22. The proteolytic activity of the starter cultures was monitored immediately after mixing of the dough and throughout the fermentation process. The proteolytic activity was assessed by analysing the salt-soluble protein (SSP) and the dioxane-soluble protein (DSP) fractions of the pizza dough by discontinuous SDS-PAGE. Only the Prt(+) starter exhibited considerable qualitative and quantitative changes in the electrophoretic patterns of the protein fractions extracted. After the fermentation, the Prt(+) and Prt(-) doughs were tested to evaluate the influence of the proteolytic activity on the mechanical properties of the dough before and after baking. Indications emerged suggesting an influence of the proteolytic activity on the viscoelasticity of pizza dough. The pizza dough with Prt(+) strains showed an increase in viscous properties during the fermentation as compared with the Prt(-) dough. Moreover, an increase in the firmness of the crumb was observed in Prt(+) baked pizza dough. 相似文献
178.
Compensation of the inherent wave front curvature in digital holographic coherent microscopy for quantitative phase-contrast imaging 总被引:1,自引:0,他引:1
Ferraro P De Nicola S Finizio A Coppola G Grilli S Magro C Pierattini G 《Applied optics》2003,42(11):1938-1946
An approach is proposed for removing the wavefront curvature introduced by the microscope imaging objective in digital holography, which otherwise hinders the phase contrast imaging at reconstruction planes. The unwanted curvature is compensated by evaluating a correcting wave front at the hologram plane with no need for knowledge of the optial parameters, focal length of the imaging lens, or distances in the setup. Most importantly it is shown that a correction effect can be obtained at all reconstruction planes. Three different methods have been applied to evaluate the correction wave front and the methods are discussed in detail. The proposed approach is demonstrated by applying digital holography as a method of coherent microscopy for imaging amplitude and phase contrast of microstructures. 相似文献
179.
W Mao R Irby D Coppola L Fu M Wloch J Turner H Yu R Garcia R Jove TJ Yeatman 《Canadian Metallurgical Quarterly》1997,15(25):3083-3090
Recent data suggest that signal transduction may have a critical role in the development and regulation of the metastatic phenotype. Here, we investigated the role of c-Src activation in the process of human colon cancer metastasis to the liver. Our data, derived from two different sets of human colon cancer cell line metastatic variants, suggest that not only do highly-metastatic cells display constitutively elevated c-Src protein kinase activity when compared to poorly metastatic cells, but also that receptor tyrosine kinases participate in the ligand-activation of c-Src above basal levels. Specifically, the epidermal growth factor receptor (EGFR), p185HER2/Neu and the hepatocyte growth factor receptor (c-Met) appear to be linked to the process because they preferentially activate c-Src in highly-metastatic cells. EGFR was found to associate with c-Src in colon cancer cells and specific inhibitors of the EGFR resulted in a reduction of c-Src activity to basal levels. In addition, c-Src transfectants displayed partially-activated EGFRs, suggesting a feedback role for c-Src in the regulation of the EGFR. p185HER2/Neu was also identified in immunocomplexes of c-Src following ligand activation of the EGFR, but only in highly-metastatic cells. Collectively, these observations suggest a paradigm whereby c-Src interacts with multiple cell-surface growth factors in a catalytic fashion for the development of tumor cells with metastatic potential. 相似文献
180.