623 research outputs found
Evaluation of E-Learning Lessons for Strengthening Early Childhood Practitioner Use of Family Capacity-Building Practices
Findings from a case study field-test evaluation of e-learning lessons for promoting early childhood intervention practitioners’ understanding and use of family capacity-building practices are described. Participants were two early childhood program directors, two early childhood technical assistance providers, and two early childhood intervention practitioners. Pattern matching was used to evaluate whether or not participants with different roles and responsibilities judged the instructional design, interactivity, video illustrations, and usefulness of the e-learning lessons similarly or differently. Results indicated that the different features of the e-learning lessons were rated highly by all but one participant and that the patterns of responses were much the same regardless of participants’ professional roles or responsibilities. Participant feedback and suggestions were used to revise the e-learning lessons and correct technical problems
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Synthesis and antibacterial profiles of targeted triclosan derivatives
There is an ongoing urgent need for new targeted antibacterial com pounds with novel mechanisms of action for the treatment of infections caused by bacteria that are resistant to currently available materials. Since the expression of glycosidase enzymes within bacteria is unequally distributed, glycoside derivatives of antibacterial agents offer potential as targeted prodrugs for bacterial infections. Herein we report the synthesis and characterisation of four α-D-glycopyranosides and three β-D-glycopyranosides of the broad antibacterial agent triclosan, in generally good synthetic yields, and with excellent purities. Each glycoside was analysed to determine its ability to inhibit the growth of a wide range of Gram-negative and Gram-positive organisms, including many of clinical significance. All of the triclosan glycosides that were synthesized demonstrated antibacterial activity against many of the organisms that were examined. For example, β-galactoside (3a) and α-arabinoside (3c) had MIC values of 0.5 μg/ ml for several strains of S. aureus and S. haemolyticus. The triclosan glycosides were also generally found to be more water soluble and much more selective than the underivatized triclosan, making them ideal both for the targeted inhibition of bacterial growth and as agents for the selective recovery of bacteria from mixed cultures. In the latter case, two Bacillus strains could be identified from various strains of Bacillus and Staphylococcus after inoculation onto Nutri ent Agar No. 2 with 0.25 μg/ ml tri closan-α-D-glucopyranoside (3e). This glucoside may, therefore, be of use for the isolation and identification of the foodpoisoing organism Bacillus cereus
Generic theory of colloidal transport
We discuss the motion of colloidal particles relative to a two component
fluid consisting of solvent and solute. Particle motion can result from (i) net
body forces on the particle due to external fields such as gravity; (ii) slip
velocities on the particle surface due to surface dissipative phenomena. The
perturbations of the hydrodynamic flow field exhibits characteristic
differences in cases (i) and (ii) which reflect different patterns of momentum
flux corresponding to the existence of net forces, force dipoles or force
quadrupoles. In the absence of external fields, gradients of concentration or
pressure do not generate net forces on a colloidal particle. Such gradients can
nevertheless induce relative motion between particle and fluid. We present a
generic description of surface dissipative phenomena based on the linear
response of surface fluxes driven by conjugate surface forces. In this
framework we discuss different transport scenarios including self-propulsion
via surface slip that is induced by active processes on the particle surface.
We clarify the nature of force balances in such situations.Comment: 22 pages, 1 figur
Phenotypes resulting from Huacaya by Huacaya, Suri by Huacaya and Suri by Suri alpaca crossings
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Hot blast stove process model and model-based controller
This paper describes the process model and model-based control techniques implemented on the hot blast stoves for the No. 7 Blast Furnace at the Inland Steel facility in East Chicago, Indiana. A detailed heat transfer model of the stoves is developed and verified using plant data. This model is used as part of a predictive control scheme to determine the minimum amount of fuel necessary to achieve the blast air requirements. The model is also used to predict maximum and minimum temperature constraint violations within the stove so that the controller can take corrective actions while still achieving the required stove performance
Highly Ordered Titanium Dioxide Nanostructures via a Simple One Step Vapor Inclusion Method in Block Copolymer Films
Nanostructured crystalline titanium dioxide (TiO2) finds applications in numerous fields such as photocatalysis or photovoltaics where its physical and chemical properties depend on its shape and crystallinity. We report a simple method of fabricating TiO2 nanowires by selective area deposition of titanium tetraisopropoxide (TTIP) and water in a CVD-based approach at low temperature by utilizing PS-b-PEO self-assembled block copolymer thin film as a template. Parameters such as exposure time to TTIP (minutes to hours), working temperature (~18 to 40 °C) and relative humidity (20 to 70 RH%) were systemically investigated through GISAXS, SEM and XPS and optimized for fabrication of TiO2 nanostructures. The resulting processing conditions yielded titanium dioxide nanowires with a diameter of 24 nm. An extra calcination step (400 – 700 °C) was introduced to burn off the remaining organic matrix and introduce phase change from amorphous to anatase in TiO2 nanowires without any loss in order
Phoretic Motion of Spheroidal Particles Due To Self-Generated Solute Gradients
We study theoretically the phoretic motion of a spheroidal particle, which
generates solute gradients in the surrounding unbounded solvent via chemical
reactions active on its surface in a cap-like region centered at one of the
poles of the particle. We derive, within the constraints of the mapping to
classical diffusio-phoresis, an analytical expression for the phoretic velocity
of such an object. This allows us to analyze in detail the dependence of the
velocity on the aspect ratio of the polar and the equatorial diameters of the
particle and on the fraction of the particle surface contributing to the
chemical reaction. The particular cases of a sphere and of an approximation for
a needle-like particle, which are the most common shapes employed in
experimental realizations of such self-propelled objects, are obtained from the
general solution in the limits that the aspect ratio approaches one or becomes
very large, respectively.Comment: 18 pages, 5 figures, to appear in European Physical Journal
Periodic and Quasiperiodic Motion of an Elongated Microswimmer in Poiseuille Flow
We study the dynamics of a prolate spheroidal microswimmer in Poiseuille flow
for different flow geometries. When moving between two parallel plates or in a
cylindrical microchannel, the swimmer performs either periodic swinging or
periodic tumbling motion. Although the trajectories of spherical and elongated
swimmers are qualitatively similar, the swinging and tumbling frequency
strongly depends on the aspect ratio of the swimmer. In channels with reduced
symmetry the swimmers perform quasiperiodic motion which we demonstrate
explicitely for swimming in a channel with elliptical cross section
Insights into the influence of solvent polarity on the crystallization of poly(ethylene oxide) spin-coated thin films via in situ grazing incidence wide-angle X-ray scattering
Controlling polymer thin-film morphology and crystallinity is crucial for a wide range of applications, particularly in thin-film organic electronic devices. In this work, the crystallization behavior of a model polymer, poly(ethylene oxide) (PEO), during spin-coating is studied. PEO films were spun-cast from solvents possessing different polarities (chloroform, THF, and methanol) and probed via in situ grazing incidence wide-angle X-ray scattering. The crystallization behavior was found to follow the solvent polarity order (where chloroform chloroform > methanol). When spun-cast from nonpolar chloroform, crystallization largely followed Avrami kinetics, resulting in the formation of morphologies comprising large spherulites. PEO solutions cast from more polar solvents (THF and methanol) do not form well-defined highly crystalline morphologies and are largely amorphous with the presence of small crystalline regions. The difference in morphological development of PEO spun-cast from polar solvents is attributed to clustering phenomena that inhibit polymer crystallization. This work highlights the importance of considering individual components of polymer solubility, rather than simple total solubility, when designing processing routes for the generation of morphologies with optimum crystallinities or morphologies
Selective molecular annealing:in situ small angle X-ray scattering study of microwave-assisted annealing of block copolymers
Microwave annealing has emerged as an alternative to traditional thermal annealing approaches for optimising block copolymer self-assembly. A novel sample environment enabling small angle X-ray scattering to be performed in situ during microwave annealing is demonstrated, which has enabled, for the first time, the direct study of the effects of microwave annealing upon the self-assembly behavior of a model, commercial triblock copolymer system [polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene]. Results show that the block copolymer is a poor microwave absorber, resulting in no change in the block copolymer morphology upon application of microwave energy. The block copolymer species may only indirectly interact with the microwave energy when a small molecule microwave-interactive species [diethylene glycol dibenzoate (DEGDB)] is incorporated directly into the polymer matrix. Then significant morphological development is observed at DEGDB loadings ≥6 wt%. Through spatial localisation of the microwave-interactive species, we demonstrate targeted annealing of specific regions of a multi-component system, opening routes for the development of "smart" manufacturing methodologies
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