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61.
Hybrid materials composed of superparamagnetic iron oxide nanoparticles (SPIONs) and lipid self-assemblies possess considerable applicative potential in the biomedical field, specifically, for drug/nutrient delivery. Recently, we showed that SPIONs-doped lipid cubic liquid crystals undergo a cubic-to-hexagonal phase transition under the action of temperature or of an alternating magnetic field (AMF). This transition triggers the release of drugs embedded in the lipid scaffold or in the water channels. In this contribution, we address this phenomenon in depth, to fully elucidate the structural details and optimize the design of hybrid multifunctional carriers for drug delivery. Combining small-angle X-ray scattering (SAXS) with a magnetic characterization, we find that, in bulk lipid cubic phases, the cubic-to-hexagonal transition determines the magnetic response of SPIONs. We then extend the investigation from bulk liquid-crystalline phases to colloidal dispersions, i.e., to lipid/SPIONs nanoparticles with cubic internal structure (“magnetocubosomes”). Through Synchrotron SAXS, we monitor the structural response of magnetocubosomes while exposed to an AMF: the magnetic energy, converted into heat by SPIONs, activates the cubic-to-hexagonal transition, and can thus be used as a remote stimulus to spike drug release “on-demand”. In addition, we show that the AMF-induced phase transition in magnetocubosomes steers the realignment of SPIONs into linear string assemblies and connect this effect with the change in their magnetic properties, observed at the bulk level. Finally, we assess the internalization ability and cytotoxicity of magnetocubosomes in vitro on HT29 adenocarcinoma cancer cells, in order to test the applicability of these smart carriers in drug delivery applications.  相似文献   
62.
Plasma fatty acid (FA) composition is known to be an indicator of dietary fat quality, but the associations of other dietary factors with plasma FA composition remain unknown in children. We investigated the cross-sectional associations of food consumption with the proportions of FA and estimated desaturase activities in plasma cholesteryl esters (CE) and phospholipids (PL) among children. The subjects were a population sample of 423 children aged 6–8 years examined at baseline of The Physical Activity and Nutrition in Children (PANIC) Study. We assessed food consumption by food records and plasma FA composition by gas chromatography. We used linear regression models adjusted for age, sex, physical activity and total energy intake to analyze the associations. A higher consumption of vegetable oil-based margarine (fat 60–80 %) was associated with a higher proportion of linoleic and α-linolenic acids in plasma CE and PL. A higher consumption of high-fiber grain products was related to a lower proportion of oleic acid in CE and PL. The consumption of candy was directly associated with the proportion of palmitoleic and oleic acid in plasma CE. The consumption of vegetable oil-based margarine was inversely associated with estimated stearoyl-CoA-desaturase activity in plasma CE and PL and the consumption of candy was directly related to it in plasma CE. The results of our study suggest that plasma FA composition is not only a biomarker for dietary fat quality but also reflects the consumption of high-fiber grain products and foods high in sugar among children.  相似文献   
63.
Silicon - Silicon (Si) combined with foliar spraying of salicylic acid (SA) can affect the absorption of this beneficial element. A study with Si non-accumulators plants (soybean and bean) observed...  相似文献   
64.
We analyze vacuum polarization effects associated with massive scalar quantum fields in a higher-dimensional de Sitter space in the presence of a global monopole. Because this analysis has been developed in pure de Sitter space, we are mainly interested on the effects induced by the presence of the global monopole. So, to achieve this objective, we calculate the corresponding Wightman function, which is expressed in an integral representation and explicitly depends on the parameters associated with the presence of the monopole and the cosmological constant. Admitting that the former is closed to unity, which corresponds to a realistic value predicted by Grand Unified Theories, it is possible to express this function as a sum of two terms: the first one corresponds to the Wightman function on the bulk where the global monopole is absent, and the second one is a contribution induced by the presence of the monopole.  相似文献   
65.
Studies based on AC high voltage tests have been done at Cepel to investigate the performance of 800 kV bushar insulators under heavy wetting conditions. Insulators were tested which are now used on si...  相似文献   
66.
The extender oil usually employed in compositions of rubbers based on styrene and butadiene (SBR) 1712 is the distilled aromatic extract (DAE). In this work, this oil was substituted by oils with low levels of polycyclic aromatic hydrocarbons (PAHs): treated residual aromatic extract (TRAE) and two naphthenic oils from different suppliers (HN1 and HN2). This substitution was performed in response to REACH Regulation (EC No. 1907/2006 European Parliament and the Council of December 18, 2006, Annex XVII), which state that the sum of individual PAHs should be below 10 mg/kg and the levels of benzo (a) pyrene (BaP) should not exceed 1 mg/kg. Infrared spectroscopy was employed to characterize the structure of crude oils and respective SBR compositions. Thermal properties of the materials were evaluated by thermogravimetry and differential scanning calorimetry. Mechanical properties as tension tests, hardness, abrasion resistance, and resilience were also determined. The final results showed that it is possible to replace the extender oil DAE for any of the oils tested, specially the naphthenic HN1, without any loss of the properties evaluated in this study for the SBR compositions. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   
67.

In open societies of agents, where agents are autonomous and heterogeneous, it is not realistic to assume that agents will always act so as to comply with interaction protocols. Thus, the need arises for a formalism to specify constraints on agent interaction, and for a tool able to observe and check for agent compliance with interaction protocols. In this paper we present a JAVA-PROLOG software component built on logic programming technology, which can be used to verify compliance of agent interaction to protocols, and that has been integrated with the PROSOCS platform.  相似文献   
68.

We investigate the use of commercial off-the-shelf (COTS) eye-trackers to automatically detect mind wandering—a phenomenon involving a shift in attention from task-related to task-unrelated thoughts—during computerized learning. Study 1 (N?=?135 high-school students) tested the feasibility of COTS eye tracking while students learn biology with an intelligent tutoring system called GuruTutor in their classroom. We could successfully track eye gaze in 75% (both eyes tracked) and 95% (one eye tracked) of the cases for 85% of the sessions where gaze was successfully recorded. In Study 2, we used this data to build automated student-independent detectors of mind wandering, obtaining accuracies (mind wandering F1?=?0.59) substantially better than chance (F1?=?0.24). Study 3 investigated context-generalizability of mind wandering detectors, finding that models trained on data collected in a controlled laboratory more successfully generalized to the classroom than the reverse. Study 4 investigated gaze- and video- based mind wandering detection, finding that gaze-based detection was superior and multimodal detection yielded an improvement in limited circumstances. We tested live mind wandering detection on a new sample of 39 students in Study 5 and found that detection accuracy (mind wandering F1?=?0.40) was considerably above chance (F1?=?0.24), albeit lower than offline detection accuracy from Study 1 (F1?=?0.59), a finding attributable to handling of missing data. We discuss our next steps towards developing gaze-based attention-aware learning technologies to increase engagement and learning by combating mind wandering in classroom contexts.

  相似文献   
69.
The problem of Information Technology energy consumption has gained much attention due to the always increasing use of IT both for business and for personal reasons. In particular, data centers are now playing a much more important role in the modern society, where the information is available all the time and everywhere. In this context, the aim of this paper is to study energy efficiency issues within data centers from the Information System perspective. The proposed approach integrates the application and infrastructure capabilities, in which the enactment of adaptation mechanisms is aligned with the business process. Based on both energy and quality dimensions of service-based applications, a model-based approach supports the formulation of new constrained optimization problem that takes into consideration over-constrained solutions where the goal is to obtain the better trade-off between energy and quality requirements. These ideas are combined within a framework where time-based analysis allow the identification of potential system threats and drive the selection of adaptation actions improving overall energy and quality requirements, represented by indicators satisfaction. In addition, the framework includes an evolution mechanism that is able to evaluate past decisions feedback in order to adjust the model according to the current underlying environment. Finally, the benefits of the approach are analyzed in an experimental setting.  相似文献   
70.
This paper presents ALIAS, an agent architecture based on intelligent logic agents, where the main form of agent reasoning is abduction. The system is particularly suited for solving problems where knowledge is incomplete, where agents may need to make reasonable hypotheses about the problem domain and other agents, and where the raised hypotheses have to be consistent for the overall set of agents. ALIAS agents are pro-active, exhibiting a goal-directed behavior, and autonomous, since each one can solve problems using its own private knowledge base. ALIAS agents are also social, because they are able to interact with other agents, in order to cooperatively solve problems. The coordination mechanisms are modeled by means of LAILA, a logic-based language which allows to express intra-agent reasoning and inter-agent coordination. As an application, we show how LAILA can be used to implement inter-agent dialogues, e.g., for negotiation. In particular, LAILA is well-suited to coordinate the process of negotiation aimed at exchanging resources between agents, thus allowing them to execute the plans to achieve their goals.  相似文献   
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