475 resultados para Variables de surface


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Information and communications technologies are a significant component of the healthcare domain and electronic health records play a major role within it. As a result, it is important that they are accepted en masse by healthcare professionals. How healthcare professionals perceive the usefulness of electronic health records and their attitudes towards them have been shown to have significant effects on their overall acceptance. This paper investigates the role of perceived usefulness and attitude on the intention to use electronic health records by future healthcare professionals using polynomial regression with response surface analysis. Results show that the relationship is more complex than predicted in prior research. The paper concludes that the predicting properties of the above determinants must be further investigated to clearly understand their role in predicting the intention to use electronic health records and in designing systems that are better adopted by healthcare professionals of the future.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Synthetic goethite and thermally treated goethite at different temperatures were used to remove phosphate from sewage. The effect of annealing temperature on phosphate removal over time was investigated. X-ray diffraction(XRD), transmission electron microscopy (TEM), N2 adsorption and desorption (BET), and infrared emission spectrum (FT-IES) were utilized to characterize the phase, morphology, specific surface area, pore distribution, and the surface groups of samples. The results show that annealed products of goethite at temperatures over 250 °C are hematite with the similar morphology as the original goethite with different hydroxyl groups and surface area. Increasing temperature causes the decrease in hydroxyl groups, consequential increase in surface area at first and then experiences a decrease (14.8–110.4–12.6 m2/g) and the subsequent formation of nanoscale pores. The variation rate of hydroxyl groups and surface area based on FT-IES and BET, respectively, are used to evaluate the effect of annealing temperature on phosphate removal. By using all of the characterization techniques, it is concluded that the changes of phosphate removal basically result from the total variation rate between hydroxyl groups and surface area.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We have developed an explanation for ultra trace detection found when using Au/Ag SERS nanoparticles linked to biochemical affinity tags, e.g. antibodies. The nanoparticle structure is not as usually assumed and the aggregated nanoparticles constitute hot spots that are indispensable for these very low levels of analyte detection, even more so when using a direct detection method.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A comprehensive study was conducted on mesoporous MCM-41. Spectroscopic examinations demonstrated that three types of silanol groups, i.e., single, (SiO)3Si-OH, hydrogen-bonded, (SiO)3Si-OH-OH-Si(SiO)3, and geminal, (SiO)2Si(OH)2, can be observed. The number of silanol groups/nm2, ?OH, as determined by NMR, varies between 2.5 and 3.0 depending on the template-removal methods. All these silanol groups were found to be the active sites for adsorption of pyridine with desorption energies of 91.4 and 52.2 kJ mol-1, respectively. However, only free silanol groups (involving single and geminal silanols) are highly accessible to the silylating agent, chlorotrimethylsilane. Silylation can modify both the physical and chemical properties of MCM-41.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Establishing age-at-death for skeletal remains is a vital component of forensic anthropology. The Suchey-Brooks (S-B) method of age estimation has been widely utilised since 1986 and relies on a visual assessment of the pubic symphyseal surface in comparison to a series of casts. Inter-population studies (Kimmerle et al., 2005; Djuric et al., 2007; Sakaue, 2006) demonstrate limitations of the S-B method, however, no assessment of this technique specific to Australian populations has been published. Aim: This investigation assessed the accuracy and applicability of the S-B method to an adult Australian Caucasian population by highlighting error rates associated with this technique. Methods: Computed tomography (CT) and contact scans of the S-B casts were performed; each geometrically modelled surface was extracted and quantified for reference purposes. A Queensland skeletal database for Caucasian remains aged 15 – 70 years was initiated at the Queensland Health Forensic and Scientific Services – Forensic Pathology Mortuary (n=350). Three-dimensional reconstruction of the bone surface using innovative volume visualisation protocols in Amira® and Rapidform® platforms was performed. Samples were allocated into 11 sub-sets of 5-year age intervals and changes associated with the surface geometry were quantified in relation to age, gender and asymmetry. Results: Preliminary results indicate that computational analysis was successfully applied to model morphological surface changes. Significant differences in observed versus actual ages were noted. Furthermore, initial morphological assessment demonstrates significant bilateral asymmetry of the pubic symphysis, which is unaccounted for in the S-B method. These results propose refinements to the S-B method, when applied to Australian casework. Conclusion: This investigation promises to transform anthropological analysis to be more quantitative and less invasive using CT imaging. The overarching goal contributes to improving skeletal identification and medico-legal death investigation in the coronial process by narrowing the range of age-at-death estimation in a biological profile.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The surface area of inhaled particles deposited in the alveolar region, as reported by the TSI nanoparticle surface area monitor (NSAM), was compared with the corresponding value estimated by a TSI scanning mobility particle sizer (SMPS) for a range of environmentally relevant aerosols, including petrol emissions, ETS, laser printer emissions, cooking emissions and ambient aerosols. The SMPS values were based on a mobility size distribution assuming spherical particles using the appropriate size-dependent alveolar-deposition factors provided by the ICRP. In most cases, the two instruments showed good linear agreement. With petrol emissions and ETS, the linearity extended to over 103 μm2 cm-3. With printer emissions, there was good linearity up to about 300 μm2 cm-3 while the NSAM increasingly overestimated the surface area at higher concentrations. The presence of a nucleation event in ambient air caused the NSAM to over-estimate the surface area by a factor of 2. We summarize these results and conclude that the maximum number concentration up to which the NSAM is accurate clearly depends on the type of aerosol being sampled and provide guidance for the use of the instrument.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Materials used in the engineering always contain imperfections or defects which significantly affect their performances. Based on the large-scale molecular dynamics simulation and the Euler–Bernoulli beam theory, the influence from different pre-existing surface defects on the bending properties of Ag nanowires (NWs) is studied in this paper. It is found that the nonlinear-elastic deformation, as well as the flexural rigidity of the NW is insensitive to different surface defects for the studied defects in this paper. On the contrary, an evident decrease of the yield strength is observed due to the existence of defects. In-depth inspection of the deformation process reveals that, at the onset of plastic deformation, dislocation embryos initiate from the locations of surface defects, and the plastic deformation is dominated by the nucleation and propagation of partial dislocations under the considered temperature. Particularly, the generation of stair-rod partial dislocations and Lomer–Cottrell lock are normally observed for both perfect and defected NWs. The generation of these structures has thwarted attempts of the NW to an early yielding, which leads to the phenomenon that more defects does not necessarily mean a lower critical force.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The addition of surface tension to the classical Stefan problem for melting a sphere causes the solution to blow up at a finite time before complete melting takes place. This singular behaviour is characterised by the speed of the solid-melt interface and the flux of heat at the interface both becoming unbounded in the blow-up limit. In this paper, we use numerical simulation for a particular energy-conserving one-phase version of the problem to show that kinetic undercooling regularises this blow-up, so that the model with both surface tension and kinetic undercooling has solutions that are regular right up to complete melting. By examining the regime in which the dimensionless kinetic undercooling parameter is small, our results demonstrate how physically realistic solutions to this Stefan problem are consistent with observations of abrupt melting of nanoscaled particles.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Boron nitride nanotubes were functionalized by microperoxidase-11 in aqueous media, showing improved catalytic performance due to a strong electron coupling 10 between the active centre of microperoxidase-11 and boron nitride nanotubes. One main application challenge of enzymes as biocatalysts is molecular aggregation in the aqueous solution. This issue is addressed by immobilization of enzymes on solid supports which 15 can enhance enzyme stability and facilitate separation, and recovery for reuse while maintaining catalytic activity and selectivity. The protein-nanoparticle interactions play a key role in bio-nanotechnology and emerge with the development of nanoparticle-protein “corona”. Bio-molecular coronas provide a 20 unique biological identity of nanosized materials.1, 2 As a structural analogue to carbon nanotubes (CNTs), Boron nitride nanotubes have boron and nitrogen atoms distributed equally in hexagonal rings and exhibit excellent mechanical strength, unique physical properties, and chemical stability at high-temperatures. 25 The chemical inertness of BN materials suits to work in hazardous environments, making them an optimal candidate in practical applications in biological and medical field.3, 4

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of this study was to compare the effectiveness of three different recovery modalities - active (ACT), passive (PAS) and contrast temperature water immersion (CTW) - on the performance of repeated treadmill running, lactate concentration and pH. Fourteen males performed two pairs of treadmill runs to exhaustion at 120% and 90% of peak running speed (PRS) over a 4-hour period. ACT, PAS or CTW was performed for 15-min after the first pair of treadmill runs. ACT consisted of running at 40% PRS, PAS consisted of standing stationary and CTW consisted of alternating between 60-s cold (10°C) and 120-s hot (42°C) water immersion. Run times were converted to time to cover set distance using critical power. Type of recovery modality did not have a significant effect on change in time to cover 400 m (Mean±SD; ACT 2.7±3.6 s, PAS 2.9±4.2 s, CTW 4.2±6.9 s), 1000 m (ACT 2.2±4.0 s, PAS 4.8±8.6 s, CTW 2.1±7.2 s) or 5000 m (ACT 1.4±29.0 s, PAS 16.7±58.5 s, CTW 11.7±33.0 s). Post exercise blood lactate concentration was lower in ACT and CTW compared with PAS. Participants reported an increased perception of recovery in the CTW compared with ACT and PAS. Blood pH was not significantly influenced by recovery modality. Data suggest both ACT and CTW reduce lactate accumulation after high intensity running, but high intensity treadmill running performance is returned to baseline 4-hours after the initial exercise bout regardless of the recovery strategy employed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A controlled layer of multi-wall carbon nanotubes (MWCNT) was grown directly on top of fluorine-doped tin oxide (FTO) glass electrodes as a surface modifier for improving the performance of polymer solar cells. By using low-temperature chemical vapor deposition with short synthesis times, very short MWCNTs were grown, these uniformly decorating the FTO surface. The chemical vapor deposition parameters were carefully refined to balance the tube size and density, while minimizing the decrease in conductivity and light harvesting of the electrode. As created FTO/CNT electrodes were applied to bulk-heterojunction polymer solar cells, both in direct and inverted architecture. Thanks to the inclusion of MWCNT and the consequent nano-structuring of the electrode surface, we observe an increase in external quantum efficiency in the wavelength range from 550 to 650 nm. Overall, polymer solar cells realized with these FTO/CNT electrodes attain power conversion efficiency higher than 2%, outclassing reference cells based on standard FTO electrodes.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The cyclic voltammetry behaviour of gold in aqueous media is often regarded in very simple terms as a combination of two distinct processes, double layer charging/discharging and monolayer oxide formation/removal. This view is questioned here on the basis of both the present results and earlier independent data by other authors. It was demonstrated in the present case that both severe cathodization or thermal pretreatment of polycrystalline gold in acid solution resulted in the appearance of substantial Faradaic responses in the double layer region. Such anamolous behaviour, as outlined recently also for other metals, is rationalized in terms of the presence of active metal atoms (which undergo premonolayer oxidation) at the electrode surface. Such behaviour, which is also assumed to correspond to that of active sites on conventional gold surfaces, is assumed to be of vital importance in electrocatalysis; in many instances the latter process is also quite marked in the double layer region.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We demonstrate a simple electrochemical route to produce uniformly sized gold nanospikes without the need for a capping agent or prior modification of the electrode surface, which are predominantly oriented in the {111} crystal plane and exhibit promising electrocatalytic and SERS properties.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Metastable, active, or nonequilibrium states due to the presence of abnormal structures and various types of defects are well known in metallurgy. The role of such states at gold surfaces in neutral aqueous media (an important electrode system in the microsensor area) was explored using cyclic voltammetry. It was demonstrated that, as postulated in earlier work from this laboratory, there is a close relationship between premonolayer oxidation, multilayer hydrous oxide reduction and electrocatalytic behaviour in the case of this and other metal electrode systems. Some of the most active, and therefore most important, entities at surfaces (e.g., metal adatoms) are not readily imageable or detectable by high resolution surface microscopy techniques. Cyclic voltammetry, however, provides significant, though not highly specific, information about such species. The main conclusion is that further practical and theoretical work on active states of metal surfaces is highly desirable as their behaviour is not simple and is of major importance in many electrocatalytic processes.