94 research outputs found
Nonlinear diffusion in two-dimensional ordered porous media based on a free volume theory.
A continuum nonlinear diffusion model is developed to describe molecular transport in ordered porous media. An existing generic van der Waals equation of state based free volume theory of binary diffusion coefficients is modified and introduced into the two-dimensional diffusion equation. The resulting diffusion equation is solved numerically with the alternating-direction fully implicit method under Neumann boundary conditions. Two types of pore structure symmetries are considered, hexagonal and cubic. The former is modeled as parallel channels while in case of the latter equal-sized channels are placed perpendicularly thus creating an interconnected network. First, general features of transport in both systems are explored, followed by the analysis of the impact of molecular properties on diffusion inside and out of the porous matrix. The influence of pore size on the diffusion-controlled release kinetics is assessed and the findings used to comment recent experimental studies of drug release profiles from ordered mesoporous silicates
More than one dynamic crossover in protein hydration water
Studies of liquid water in its supercooled region have led to many insights
into the structure and behavior of water. While bulk water freezes at its
homogeneous nucleation temperature of approximately 235 K, for protein
hydration water, the binding of water molecules to the protein avoids
crystallization. Here we study the dynamics of the hydrogen bond (HB) network
of a percolating layer of water molecules, comparing measurements of a hydrated
globular protein with the results of a coarse-grained model that has been shown
to successfully reproduce the properties of hydration water. With dielectric
spectroscopy we measure the temperature dependence of the relaxation time of
protons charge fluctuations. These fluctuations are associated to the dynamics
of the HB network of water molecules adsorbed on the protein surface. With
Monte Carlo (MC) simulations and mean--field (MF) calculations we study the
dynamics and thermodynamics of the model. In both experimental and model
analyses we find two dynamic crossovers: (i) one at about 252 K, and (ii) one
at about 181 K. The agreement of the experiments with the model allows us to
relate the two crossovers to the presence of two specific heat maxima at
ambient pressure. The first is due to fluctuations in the HB formation, and the
second, at lower temperature, is due to the cooperative reordering of the HB
network
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Temperature dependence of protein dynamics simulated with three different water models
The effect of variation of the water model on the temperature dependence of protein and hydration water dynamics is examined by performing molecular dynamics simulations of myoglobin with the TIP3P, TIP4P, and TIP5P water models and the CHARMM protein force field at temperatures between 20 and 300 K. The atomic mean-square displacements, solvent reorientational relaxation times, pair angular correlations between surface water molecules, and time-averaged structures of the protein are all found to be similar, and the protein dynamical transition is described almost indistinguishably for the three water potentials. The results provide evidence that for some purposes changing the water model in protein simulations without a loss of accuracy may be possible
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DOE Project on Heavy Vehicle Aerodynamic Drag FY 2005 Annual Report
Class 8 tractor-trailers consume 11-12% of the total US petroleum use. At high way speeds, 65% of the energy expenditure for a Class 8 truck is in overcoming aerodynamic drag. The project objective is to improve fuel economy of Class 8 tractor-trailers by providing guidance on methods of reducing drag by at least 25%. A 25% reduction in drag would present a 12% improvement in fuel economy at highway speeds, equivalent to about 130 midsize tanker ships per year. Specific goals include: (1) Provide guidance to industry in the reduction of aerodynamic drag of heavy truck vehicles; and (2) Establish a database of experimental, computational, and conceptual design information, and demonstrate the potential of new drag-reduction devices
From theoretical concepts to policies and applied programmes: the landscape of integration of oral health in primary care
Background: Despite its importance, the integration of oral health into primary care is still an emerging practice in
the field of health care services. This scoping review aims to map the literature and provide a summary on the
conceptual frameworks, policies and programs related to this concept.
Methods: Using the Levac et al. six-stage framework, we performed a systematic search of electronic databases,
organizational websites and grey literature from 1978 to April 2016. All relevant original publications with a focus
on the integration of oral health into primary care were retrieved. Content analyses were performed to synthesize
the results.
Results: From a total of 1619 citations, 67 publications were included in the review. Two conceptual
frameworks were identified. Policies regarding oral heath integration into primary care were mostly oriented
toward common risk factors approach and care coordination processes. In general, oral health integrated care
programs were designed in the public health sector and based on partnerships with various private and
public health organizations, governmental bodies and academic institutions. These programmes used various
strategies to empower oral health integrated care, including building interdisciplinary networks, training nondental
care providers, oral health champion modelling, enabling care linkages and care coordinated process,
as well as the use of e-health technologies. The majority of studies on the programs outcomes were
descriptive in nature without reporting long-term outcomes.
Conclusions: This scoping review provided a comprehensive overview on the concept of integration of oral
health in primary care. The findings identified major gaps in reported programs outcomes mainly because of
the lack of related research. However, the results could be considered as a first step in the development of
health care policies that support collaborative practices and patient-centred care in the field of primary care
sector
Development, design, and conceptual issues of project zero exposure: A program to protect young children from tobacco smoke exposure
A qualitative investigation of the role of sport coaches in designing and delivering a complex community sport intervention for increasing physical activity and improving health
© The Author(s).
Background
Community sport can potentially help to increase levels of physical activity and improve public health. Sport coaches have a role to play in designing and implementing community sport for health. To equip the community sport workforce with the knowledge and skills to design and deliver sport and empower inactive participants to take part, this study delivered a bespoke training package on public health and recruiting inactive people to community sport for sport coaches. We examined the views of sport coach participants about the training and their role in designing and delivering a complex community sport intervention for increasing physical activity and improving health.
Methods
Semi-structured interviews were conducted with paid full-time sport coaches (n = 15) and community sport managers and commissioners (n = 15) with expertise in sport coaching. Interviews were conducted by a skilled interviewer with in-depth understanding of community sport and sport coach training, transcribed verbatim and analysed using thematic analysis.
Results
Three key themes were identified showing how the role of sport coaches can be maximised in designing and delivering community sport for physical activity and health outcomes, and in empowering participants to take part. The themes were: (1) training sport coaches in understanding public health, (2) public involvement in community sport for health, and (3) building collaborations between community sport and public health sectors.
Conclusion
Training for sport coaches is required to develop understandings of public health and skills in targeting, recruiting and retaining inactive people to community sport. Public involvement in designing community sport is significant in empowering inactive people to take part. Ongoing knowledge exchange activities between the community sport and public health sector are also required in ensuring community sport can increase physical activity and improve public health.Sport England’s Get Healthy Get Active Award UR
Structure and Dynamics of Biological Systems: Integration of Neutron Scattering with Computer Simulation
The combination of molecular dynamics simulation and neutron scattering techniques has emerged as a highly synergistic approach to elucidate the atomistic details of the structure, dynamics and functions of biological systems. Simulation models can be tested by calculating neutron scattering structure factors and comparing the results directly with experiments. If the scattering profiles agree the simulations can be used to provide a detailed decomposition and interpretation of the experiments, and if not, the models can be rationally adjusted. Comparison with neutron experiment can be made at the level of the scattering functions or, less directly, of structural and dynamical quantities derived from them. Here, we examine the combination of simulation and experiment in the interpretation of SANS and inelastic scattering experiments on the structure and dynamics of proteins and other biopolymers
Ions and the Protein Surface Revisited: Extensive Molecular Dynamics Simulations and Analysis of Protein Structures in Alkali-Chloride Solutions
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