154 research outputs found
Implications of the financial crisis on the European tourism
The last 12-18 months have been one of the most challenging periods in the history of tourism. Both business and consumer confidence were bound to be affected. Similarly to previous crises, the consumer tended to travel closer to home during 2009. People have not only travelled less often and less far, but they have spent less, taking shorter trips and ‘trading down’. Many have also reduced their frequency of travel, especially in terms of short breaks, in order to protect their main holidays
Ultrasound assisted electrodeposition of Cu-SiO2 composite coatings: Effect of particle surface chemistry
Electrodeposition of Cu-SiO2 composite coatings from an alkaline non-cyanide electrolyte containing glutamate as complexing agent was studied. Silica mesoporous particles were synthesized using a modified Stöber methodology, and later their surface chemistry was changed by functionalizing them with 3-aminopropyltriethoxysilane. Particles microstructure and morphology were characterized (SEM, TEM, XRD) and their charging behavior in several electrolytes was studied through ζ-potential measurements. Galvanostatic deposition was performed in electrolytes containing both as-prepared and functionalized SiO2 at various current densities, and the influence of ultrasonic irradiation (37 Hz) was evaluated. For some experiments, 1.5 g L− of Polyquaternium 7 were added to the solution. SEM and XRD were used to characterized coatings morphology and microstructure, whereas EDS was used to estimate SiO2 wt%. The results showed that the effect of ultrasound on the codeposition process depends on current density and particle surface chemistry. All the trends observed in this study could be explained taking into account ζ-potential values recorded and previously reported theories. Adjusting the experimental conditions, it was possible to obtain deposits with SiO2 contents of ≈5 wt%. Finally, it was found that both ultrasonic irradiation and Polyquaternium 7 affect the morphology and crystal orientation of the deposits.Fil: Bengoa, Leandro Nicolás. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Ispas, Adriana. Technische Universität Ilmenau; AlemaniaFil: Bengoa, Jose Fernando. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; ArgentinaFil: Bund, A.. Technische Universität Ilmenau; AlemaniaFil: Egli, Walter Alfredo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Tecnología de Pinturas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones en Tecnología de Pinturas; Argentin
First-principles molecular-dynamics simulations of a hydrous silica melt: Structural properties and hydrogen diffusion mechanism
We use {\it ab initio} molecular dynamics simulations to study a sample of
liquid silica containing 3.84 wt.% HO.We find that, for temperatures of
3000 K and 3500 K,water is almost exclusively dissolved as hydroxyl groups, the
silica network is partially broken and static and dynamical properties of the
silica network change considerably upon the addition of water.Water molecules
or free O-H groups occur only at the highest temperature but are not stable and
disintegrate rapidly.Structural properties of this system are compared to those
of pure silica and sodium tetrasilicate melts at equivalent temperatures. These
comparisons confirm the picture of a partially broken tetrahedral network in
the hydrous liquid and suggest that the structure of the matrix is as much
changed by the addition of water than it is by the addition of the same amount
(in mole %) of sodium oxide. On larger length scales, correlations are
qualitatively similar but seem to be more pronounced in the hydrous silica
liquid. Finally, we study the diffusion mechanisms of the hydrogen atoms in the
melt. It turns out that HOSi triclusters and SiO dangling bonds play a
decisive role as intermediate states for the hydrogen diffusion.Comment: 25 pages, 18 figures. submitte
Nanoparticle gas phase electrodeposition: fundamentals, fluid dynamics, and deposition kinetics
This communication uncovers missing fundamental elements and an expanded model of gas phase electrodeposition; a relatively new and in large parts unexplored process, which combines particle generation, transport zone and deposition zone in an interacting setup. The process enables selected area deposition of charged nanoparticles that are dispersed and transported by a carrier gas at atmospheric pressure conditions. Two key parameters have been identified: carrier gas flow rate and spark discharge power. Both parameters affect electrical current carried by charged species, nanoparticle mass, particle size and film morphology. In combination, these values enable to provide an estimate of the gas flow dependent Debye length. Together with Langmuir probe measurements of electric potential and field distribution, the transport can be described and understood. First, the transport of the charged species is dominated by the carrier gas flow. In close proximity, the transport is electric field driven. The transition region is not fixed and correlates with the electric potential profile, which is strongly dependent on the deposition rate. Considering the film morphology, the power of the discharge turns out to be the most relevant parameter. Low spark power combined with low gas flow leads to dendritic film growth. In contrast, higher spark power combined with higher gas flow produces compact layers
Impact of airport green atmospherics on mental health value, image, and loyalty among visitors and workers
Nature‐based solutions (NBS) are becoming increasingly crucial as NBS brings diverse health‐related benefits to travelers and workers in the tourism business sector. This research explored the influence of green atmospherics as NBS on airport occupants' mental health value, image, and loyalty generation processes. A quantitative approach with a field survey method was employed. A structural equation modeling and metric invariance test were used as data analysis technique. Our empirical result revealed that green atmospherics as NBS significantly improve the occupants' mental health value and image of the airport, and these variables contribute to their loyalty enhancement for the airport. The effect of green spaces and natural surroundings on loyalty was maximized through mental health value and image. In addition, the linkages from natural surroundings to mental health value and image were stronger in the visitor group whereas the mental health value—loyalty relation was stronger in the worker group
New fitting scheme to obtain effective potential from Car-Parrinello molecular dynamics simulations: Application to silica
A fitting scheme is proposed to obtain effective potentials from
Car-Parrinello molecular dynamics (CPMD) simulations. It is used to
parameterize a new pair potential for silica. MD simulations with this new
potential are done to determine structural and dynamic properties and to
compare these properties to those obtained from CPMD and a MD simulation using
the so-called BKS potential. The new potential reproduces accurately the liquid
structure generated by the CPMD trajectories, the experimental activation
energies for the self-diffusion constants and the experimental density of
amorphous silica. Also lattice parameters and elastic constants of alpha-quartz
are well-reproduced, showing the transferability of the new potential.Comment: 6 pages, 5 figure
Automated information system as quality management providing human tissue banks
School of Management, Nicolae Testemitsanu State University of Medicine and Pharmacy, Info World Company, Laboratory of Tissue Engineering and Cell Cultures,
Bank of Human TissuesBackground: Modern tissue bank should have management autonomy, to be equipped with modern equipment for tissue grafts procurement,
processing, preservation and storage that met the requirements of the profile structures of the EU Directives and Authorized National Health Services.
Material and methods: Article represents the analysis of the needs to create and use in human tissues and cells bank an automated information system
(AIS) to provide qualitative and safe tissue and cells grafts for transplantation in the Republic of Moldova. Automated Information System components
are analyzed and characterized, elucidated the functions they have to fulfill, their role in ensuring the effective management of human tissue bank (HTB)
in providing secure grafts for health system in the Republic of Moldova.
Results: Basic functions of the HTB AIS include: management of the life cycle of donated products; information about products recording and
storing; grafts records and relevant information about them; monitoring of the stored products; indexing exactly the products location in storage devices; a
comprehensive view of patient information products; listing information in real and historical time by textual and graphical means; generating and scanning
labels for each product; evidence of testing and validation samples; view reports using aggregate data; restricting access rights per each group of users.
Conclusions: Thus it appears that AIS is an important element in ensuring a strict accounting of human allergic graft throughout their movement
from the procurement, processing, validation, storage, distribution and transplantation. AIS also permits easier integration into the European network
for tissue, because it allows encoding of grafts according to European unique codes way enabling the identification of tissue grafts as Bank products and
follow their path. The computerized record of practical grafts excludes human errors in grafts distribution
Computational Modeling of Silicate Glasses: A Quantitative Structure-Property Relationship Perspective
This article reviews the present state of Quantitative Structure-Property
Relationships (QSPR) in glass design and gives an outlook into future developments.
First an overview is given of the statistical methodology, with particular emphasis
to the integration of QSPR with molecular dynamics simulations to derive informative
structural descriptors. Then, the potentiality of this approach as a tool for
interpretative and predictive purposes is highlighted by a number of recent inspiring
applications
Comparative classical and ab initio Molecular Dynamics study of molten and glassy germanium dioxide
A Molecular Dynamics (MD) study of static and dynamic properties of molten
and glassy germanium dioxide is presented. The interactions between the atoms
are modelled by the classical pair potential proposed by Oeffner and Elliott
(OE) [Oeffner R D and Elliott S R 1998, Phys. Rev. B, 58, 14791]. We compare
our results to experiments and previous simulations. In addition, an ab initio
method, the so-called Car-Parrinello Molecular Dynamics (CPMD), is applied to
check the accuracy of the structural properties, as obtained by the classical
MD simulations with the OE potential. As in a similar study for SiO2, the
structure predicted by CPMD is only slightly softer than that resulting from
the classical MD. In contrast to earlier simulations, both the static structure
and dynamic properties are in very good agreement with pertinent experimental
data. MD simulations with the OE potential are also used to study the
relaxation dynamics. As previously found for SiO2, for high temperatures the
dynamics of molten GeO2 is compatible with a description in terms of mode
coupling theory.Comment: 27 pages, 16 figure
- …