1,492 research outputs found
Study and design of a device that applies adhesive tape
This work describes all the development of a mechanical design that have been realized for an industrial semi device, whose functionality is to apply adhesive tape around a cylindrical body with high level of flexibility. With all the study realized it was possible to achieve a 3D virtual prototype with the conceptual idea obtained and to determine the critical key issues of the device. Those points should be analysed during the testing phase using a physical prototype.info:eu-repo/semantics/publishedVersio
Urban form indicators as proxy on the noise exposure of buildings
Available online 27 September 2013The present paper aims to address the problems of the urban environment as an area of interaction
between urban forms and urban noise. This interaction is intended to be monitored using urban indica-tors, by comparing the effects of noise propagation using models of urban forms. The model of noise pre-diction allowed developing noise studies in facades, resulting in noise levels in a calculation grid located
in the building facades. The study will allow the creation of different scenarios and anticipate as early as
in the preliminary building design phase, which facades would be exposed to higher noise levels. The
effects of noise in facades can then be minimized in advance, by adjusting the layout of the urban typology
UM ESTUDO DOS EFEITOS DE ALTERAÇÕES DO PREÇO DA NAFTA NA FORMAÇÃO DE PREÇOS DA CADEIA PETROQUÍMICA
(R)-(1-Ammoniopropyl)phosphonate
The title compound, C3H10NO3P, crystallizes in its zwitterionic form, H3N+CH(C2H5)PO(O−)(OH), with the asymmetric unit being composed by two of such entities (Z′ = 2). The crystal packing leads to a sequence of hydrophobic and hydrophilic layers. While the hydrophobic layer comprises the aliphatic substituent groups, the hydrophilic one is held together by a series of strong and rather directional N+—H⋯O and O—H⋯O hydrogen bonds
Subgoal- and goal-related reward prediction errors in medial prefrontal cortex
A longstanding view of the organization of human and animal behavior holds that behavior is hierarchically organizedin other words, directed toward achieving superordinate goals through the achievement of subordinate goals or subgoals. However, most research in neuroscience has focused on tasks without hierarchical structure. In past work, we have shown that negative reward prediction error (RPE) signals in medial prefrontal cortex (mPFC) can be linked not only to superordinate goals but also to subgoals. This suggests that mPFC tracks impediments in the progression toward subgoals. Using fMRI of human participants engaged in a hierarchical navigation task, here we found that mPFC also processes positive prediction errors at the level of subgoals, indicating that this brain region is sensitive to advances in subgoal completion. However, when subgoal RPEs were elicited alongside with goal-related RPEs, mPFC responses reflected only the goal-related RPEs. These findings suggest that information from different levels of hierarchy is processed selectively, depending on the task context
Time-to-Arrival and Useful Field of View: Associations with Reported Driving Difficulties Among Older Adults
The purpose of this study was to determine self-reported driving difficulties related to time-to-arrival (TTA) and/or useful field of view (UFOV), to identify associations between TTA and UFOV, and to compare the TTA estimated accuracy between different vehicle speed approaches. Thirty-eight male and female active drivers ages 61 to 81 years (70,2 ± 5,0 years) participated in this study. The UFOV® test was applied. TTA was studied with a removal paradigm, using two vehicle speeds (50 and 70km/h) for data collection. A driving habits questionnaire was administered, including items concerning driving difficulties. Results showed that lower performances in divided attention (subtest 2 of UFOV®) were significantly associated with reported difficulties in hightraffic intersections, trouble seeing the signs in time to respond to them, and problems judging the speed or distance of an approaching vehicle. Concerning TTA, greater response bias and/or greater response inconsistency were significantly associated with difficulties in overtaking other cars, difficulties seeing the signs in time to react to them, difficulties in the speed or distance perception of an oncoming vehicle. Low associations were found between UFOV and TTA measures. TTA estimated accuracy increased when the vehicle traveled at higher speeds. We concluded that both TTA and UFOV seem to be important measures to identify driving difficulties in older adults. The TTA could be relevant in measuring specific aspects of visual information processing in addition to other instruments like UFOV®
Characterization of Ni-CNTs Nanocomposites Produced by Ball-Milling
This research focuses on the characterization of a metal matrix nanocomposite (MMNC) comprised of a nickel matrix reinforced by carbon nanotubes (CNTs). The aim of this study was to characterize Ni-CNTs nanocomposites produced by powder metallurgy using ball-milling. CNTs were initially untangled using ultrasonication followed by mixture/dispersion with Ni powder by ball-milling for 60, 180, or 300 min. The mixtures were cold-pressed and then pressureless sintered at 950 degrees C for 120 min under vacuum. Their microstructural characterization was mainly performed by optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The mechanical properties were evaluated by Vickers microhardness. The results indicate that combining ultrasonication and ball-milling can successfully produce Ni-CNTs nanocomposites. The ball-milling time has a significant effect on both the CNT dispersion and the final nanocomposite microstructure
EBSD Analysis of Metal Matrix Nanocomposite Microstructure Produced by Powder Metallurgy
The development of metal nanocomposites reinforced by carbon nanotubes (CNTs) remains a focus of the scientific community due to the growing need to produce lightweight advanced materials with unique mechanical properties. However, for the successful production of these nanocomposites, there is a need to consolidate knowledge about how reinforcement influences the matrix microstructure and which are the strengthening mechanisms promoting the best properties. In this context, this investigation focuses on the study of the reinforcement effect on the microstructure of an Ni-CNT nanocomposites produced by powder metallurgy. The microstructural evolution was analysed by electron backscattered diffraction (EBSD). The EBSD results revealed that the dispersion/mixing and pressing processes induce plastic deformation in the as-received powders. The dislocation structures produced in those initial steps are partially eliminated in the sintering process due to the activation of recovery and recrystallization mechanisms. However, the presence of CNTs in the matrix has a significant effect on the dislocation annihilation, thus reducing the recovery of the dislocation structures
Objective vs subjective vault measurement after myopic implantable collamer lens implantation
PURPOSE: To evaluate the relationship between subjective measurements of vault and objective values measured with Visante optical coherence tomography (OCT) in eyes receiving an implantable contact lens (ICL) for myopia correction.
DESIGN: Observational cross-sectional study.
METHODS:
SETTING: Fernández-Vega Ophthalmological Institute, Oviedo, Spain.
PATIENTS: Four hundred and fifty-two eyes from 246 patients were elected to be implanted with a Visian ICL V4 (STAAR Surgical Inc, Monrovia, California, USA).
OBSERVATION PROCEDURES: Subjective and objective measurements of vault after implantation of ICL.
MAIN OUTCOME MEASURES: Subjective vault classified in 5 levels assessed using an optical section during slit-lamp examination. Objective vault was measured with Visante OCT (Carl Zeiss Meditec Inc, Dublin, California, USA).
RESULTS: Average values of objective and subjective vault were 414 +/- 228 microm and 2.1 +/- 1.0, respectively and both parameters were highly correlated (r = 0.82; P < .001). Differences in average objective vault were statistically significant among the 5 groups of subjective vault (P < .001). Subjective vault 0 corresponded to a mean OCT value of 62 +/- 49 microm with 99% confidence interval (CI) [38; 86] microm; eyes with vault 1 to 203 +/- 93 microm with 99% CI [176; 230] microm; eyes with vault 2 to 402 +/- 131 microm with 99% CI [378; 425] microm; eyes with vault 3 to 594 +/- 146 microm, 99% CI [554; 633] microm; and vault 4 to 794 +/- 182 microm with 99% CI [713; 875] microm.
CONCLUSIONS: Subjective and objective values of vault are highly correlated. In 99% of cases within the CI, objective values for eyes subjectively classified within a certain level vary within a narrow interval (+/-25 to 80 microm) around the mean value, and this interval is characteristic of each subjective level.THIS STUDY WAS SUPPORTED IN PART BY A UNIVERSITAT DE VALENCIA RESEARCH GRANT NO. UV-AE-20070225#, (DR Montes-Mico) and Fundacao para a Ciencia e Tecnologia of Portugal Grant no. FCT-SFRH-BD-34303-2007= (Dr Fernandes). The authors indicate no financial conflict of interest. Involved in design and conduct Of Study (J.F.A., C.L., A.P., P.F., J.GAM., R.M.-M.); collection, management, analysis, and interpretation of the data (J.F.A., C.L., A.P., P.F., J.G.-M., R.M.-M.); and preparation, review, or approval of the manuscript (J.F.A., C.L., P.F., J.G.-M., R.M.-M.). The study was approved by the Fernandez-Vega Ophthalmological Institutional Review Board. The study protocol was approved by and all study procedures adhered to the recommendations of the Declaration of Helsinki
Additive manufacturing of bioactive glass in a biodegradable matrix
Bioactive glass can induce a specific and fast response in the human body that supports tissue regeneration. It is possible to control the design of customized bioapplications with advanced technologies. Although currently used in research, only a few of these technologies have been approved by the FDA to be applied in Tissue Engineering. There is dedicated additive manufacturing equipment to manufacture biomaterials. Since they are emerging technologies in emerging fields of application it is necessary to study and develop formulations with suitable processing characteristics [1].
Formulations of bioactive glass (CaO·P2O5·MgO·SiO2 system) in two different biodegradable matrices (polylactide (PLA) and polycaprolactone (PCL)) were prepared and processed by material extrusion process, namely by Fused Filament Fabrication technique.. The polymer (PLA or PCL) involves bioactive particles in biocompatible media and allows to acquire extrudable skills. The formulations with different solid contents (20–50 wt.%) were prepared using a brabender mixer type and were characterized by different techniques (e.g., X-ray diffraction (XRD), differential scanning calorimetry (DSC), melt flow index (MFI)).
The inorganic particles influence the rheological and thermal properties of bioactive glass composites. The viscosity decreases with the increase of bioactive glass content in the polymer matrix. Mechanical standard samples and scaffolds were printed and characterized. Bioactive glass composites until 40 wt.% of solid content can be printed. The bioactive glass improves the mechanical resistance of composites compared to a neat polymer matrix. However, formulations with high bioactive glass solid content (50 wt.%) showed printing limitations by their brittleness and clogging tendency.publishe
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