The shoving model for the glass-former LiCl center dot 6H(2)O: A molecular dynamics simulation study

Molecular dynamics (MD) simulations of LiCl center dot 6H(2)O Showed that the diffusion coefficient D, and also I lie structural relaxation time <tau >, follow a power law at high temperatures, D(-1) proportional to (T - T(0))(-mu), with the same experimental parameters for viscosity (T(0) = 207 K, mu = 2.08). Decoupling between D and <tau > occurs at T(x) similar to 1.1 T(0). High frequency acoustic excitations for the LiCl center dot 6H(2)O model were obtained by the calculation of time correlation functions of mass current fluctuations. The temperature dependence of the instantaneous shear modulus, G,(T), was considered in the shoving model for supercooled liquids [J.C. Dyre, T. Christensen, N.B. Olsen, J. Non-Cryst. Solids 352 (2006) 4635] resulting in a linear relationship log (D(-1)) vs. G root T. (C) 2009 Elsevier B.V. All rights reserved.

Evaluation of intramolecular energy transfer process in the lanthanide(III) bis- and tris-(TTA) complexes: Photoluminescent and triboluminescent behavior

This work reports the energy transfer mechanism process of [Eu(TTA)(2)(NO(3))(TPPO)(2)] (bis-TTA complex) and [Eu(TTA)(3)(TPPO)(2)] (tris-TTA complex) based on experimental and theoretical spectroscopic properties, where TTA = 2-thienoyltrifluoroacetone and TPPO = triphenylphosphine oxide. These complexes were synthesized and characterized by elemental analyses, infrared spectroscopy and thermogavimetric analysis. The theoretical complexes geometry data by using Sparkle model for the calculation of lanthanide complexes (SMLC) is in agreement with the crystalline structure determined by single-crystal X-ray diffraction analysis. The emission spectra for [Gd(TTA)(3)(TPPO)(2)] and [Gd(TTA)(2) (NO(3))(TPPO)(2)] complexes are associated to T -> S(0) transitions centered on coordinated TTA ligands. Experimental luminescent properties of the bis-TTA complex have been quantified through emission intensity parameters Omega(lambda)(lambda = 2 and 4), spontaneous emission rates (A(rad)), luminescence lifetime (tau), emission quantum efficiency (eta) and emission quantum yield (q), which were compared with those for tris-TTA complex. The experimental data showed that the intensity parameter value for bis-TTA complex is twice smaller than the one for tris-TTA complex, indicating the less polarizable chemical environment in the system containing nitrate ion. A good agreement between the theoretical and experimental quantum yields for both Eu(Ill) complexes was obtained. The triboluminescence (TL) of the [Eu(TTA)(2)(NO(3))(TPPO)(2)] complexes are discussed in terms of ligand-to-metal energy transfer. (c) 2007 Elsevier B.V. All fights reserved.

Interfacial Electron Transfer Dynamics Following Laser Flash Photolysis of [Ru(bpy)(2)((4,4 `-PO(3)H(2))(2)bpy)](2+) in TiO(2) Nanoparticle Films in Aqueous Environments

Nanosecond laser flash photolysis has been used to investigate injection and back electron transfer from the complex [(Ru-(bpy)(2)(4,4`-(PO(3)H(2))(2)bpy)](2+) surface-bound to TiO(2) (TiO(2)-Ru(II)). The measurements were conducted under conditions appropriate for water oxidation catalysis by known single-site water oxidation catalysts. Systematic variations in average lifetimes for back electron transfer, <tau(bet)> - were observed with changes in pH, surface coverage, incident excitation intensity, and applied bias. The results were qualitatively consistent with a model involving rate-limiting thermal activation of injected electrons from trap sites to the conduction band or shallow trap sites followed by site-to-site hopping and interfacial electron transfer, TiO(2)(e(-))-Ru(3+) -> TiO(2)-Ru(2+). The appearance of pH-dependent decreases in the efficiency of formation of TiO(2)-Ru(3+) and in incident-photon-to-current efficiencies with the added reductive scavenger hydroquinone point to pH-dependent back electron transfer processes on both the sub-nanosecond and millisecond-microsecond time scales, which could be significant in limiting long-term storage of multiple redox equivalents.

Synthesis, characterization and spectroscopic investigation of new tetrakis(acetylacetonato)thulate(III) complexes containing alkaline metals as countercations

In this work a series of tetrakis complexes C[Tm(acac)(4)] where C(+) = Li(+) Na(+) and K(+) countercations and acac = acetylacetonate ligand were synthesized and characterized for photoluminescence investigation The relevant aspect is that these complexes are water-free in the first coordination sphere The emission spectra of the tetrakis Tm(3+)-complexes present narrow bands characteristic of the (1)G(4)->(3)H(6) (479 nm) (1)G(4)->(3)F(4) (650 nm) and (1)G(4) ->(3)H(5) (779 nm) transitions of the Tm(3+) ion with the blue emission color at 479 nm as the most prominent one The lifetime values (tau) of the emitting (1)G(4) level of the C[Tm(acac)(4)] complexes were 344 360 and 400 ns for the Li(+) Na(+) and K(+) countercations respectively showing an increasing linear behavior versus the ionic radius of the alkaline ion An efficient intramolecular energy transfer process from the triplet state (T) of the ligands to the emitting (1)G(4) state of the Tm(3+) ion is observed This fact together with the absence of water molecules in first coordination sphere allows these tetrakis Tm(3+)-complexes to act as efficient blue light conversion molecular devices (c) 2010 Elsevier B V All rights reserved

Interaction of bovine serum albumin (BSA) with ionic surfactants evaluated by electron paramagnetic resonance (EPR) spectroscopy

EPR spectra of 5- and 16-doxyl stearic acid nitroxide probes (5-DSA and 16-DSA, respectively) bound to bovine serum albumin (BSA) revealed that in the presence of ionic surfactants, at least, two label populations coexist in equilibrium. The rotational correlation times (tau) indicated that component I displays a more restricted mobility state, associated to the spin labels bound to the protein; the less immobilized component 2 is due to label localization in the surfactant aggregates. For both probes, the increase of surfactant concentration leads to higher motional levels of component 1 followed by a simultaneous decrease of this fraction of nitroxides and its conversion into component 2. For 10 mM cethyltrimethylammonium chloride (CTAC), the nitroxides are 100% bound to the protein, whereas at 10mM N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) and sodium dodecyl sulfate (SDS) the fractions of bound nitroxides are reduced to 18% and 86%, respectively. No significant polarity changes were observed in the whole surfactant concentration range for component 1. Moreover, at higher surfactant concentration, component 2 exhibited a similar polarity as in the pure surfactant micelles. For 16-DSA the surfactant effect is different: at 10mM of HPS and CTAC the fractions of bound nitroxides are 76% and 49%, respectively, while at 10 mM SDS they are present exclusively in a micellar environment, consistent with 100% of component 2. Overall, both SDS and HPS are able to effectively displace the nitroxide probes from the protein binding sites. while CTAC seems to affect the nitroxide binding to a significantly smaller extent. (C) 2008 Elsevier B.V. All rights reserved.

Banjos on the snowy : implementing e-activism in education

e-Activism (the use of ICT in support of environmental action) aims to develop students' knowledge, skills and attitudes to make them proficient in using ICT to achieve environmental and political goals.  This requires teachers to be able to create appropriate ICT-based learning environments.  This paper dicusses a particular pedagogical design and demonstrates its relationship to real-world political and environmental action.

City-to-surf - a peer-to-peer model of on-line professional development: a collaborative mentoring model

This project explores the potential of electronic communications to support peer-to-peer interaction between separate whole-school communities as a means of providing both authentic, situated, professional development for teachers, concurrent with the development of enhanced student learning outcomes, and the intentional sharing of school 'culture'.  The intense use of telecommunications by both teacher and students in a 'many-to-many' manner provides rich opportunities for teachers to rethink their pedagogy, reconceptualise their classroom culture, and for students to see teachers as learners 'in situ'.  An extensive trial between two schools some 120km apart has demonstrated the basic functionality of the model.  This paper discusses the origins of the project, findings from the trial, and the nature of the changes to be made to the model to enhance its effects.

Effects of approach velocity and foot-target characteristics on the visual regulation of step length

Two questions emerge from the literature concerning the perceptual-motor processes underlying the visual regulation of step length. The first concerns the effects of velocity on the onset of visual control (VCO), when visual regulation of step length begins during goal-directed locomotion. The second concerns the effects of different obstacles such as a target or raised surface on step length regulation. In two separate experiments, participants (Experiment 1 & 2: n=12, 6 female, 6 male) walked, jogged, or sprinted towards an obstacle along a 10 m walkway, consisting of two marker-strips with alternating black and white 0.50 m markings. Each experiment consisted of three targeting or obstacle tasks with the requirement to both negotiate and continue moving (run-through) through the target. Five trials were conducted for each task and approach speed, with trials block randomised between the six participants of each gender. One 50 Hz video camera panned and filmed each trial from an elevated position, adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. Results for the targeting tasks indicate a linear relationship between approach velocity and accuracy of final foot placement (r=0.89). When foot placement was highly constrained by the obstacle step length shortened during the entire approach. VCO was found to occur at an earlier tau-margin for lower approach velocities for both experiments, indicating that the optical variable ‘tau' is affected by approach velocity. A three-phase kinematic profile was found for all tasks, except for the take-off board condition when sprinting. Further research is needed to determine whether this velocity affect on VCO is due to ‘whole-body' approach velocity or whether it is a function of the differences between gait modes.

The effects of target length on the visual control of step length for hard and soft impacts

Adjustments to gait were examined when positioning the foot within a narrow target at the end of an approach for two impact conditions, hard and soft. Participants (6 M, 6 F) ran toward a target of three lengths along a 10-m walkway consisting of two marker strips with alternating black and white 0.5-m markings. Five trials were conducted for each target length and impact task, with trials block randomized between the 6 participants of each gender. A 50-Hz digital video camera panned and filmed each trial from an elevated position adjacent to the walkway. Video footage was digitized to deduce the gait characteristics. A linear speed/accuracy tradeoff between target length and approach time was found for both impact tasks (hard, r = 0.99, p < 0.01; soft, r = 0.96, p < 0.05). For the hard-impact task, visual control time increased linearly (r = 0.99, p < 0.05) when whole-body approach velocity decreased. Visual control time was unaffected by whole-body approach velocity in the soft-impact task. A constant tau-margin of 1.08 describes the onset of visual control when approaching a target while running, with the control of braking during visual control described by a tau-dot of –0.85. Further research is needed to examine the control of braking in different targeting tasks.

The salt wedge position in a bar-blocked estuary subject to pulsed inflows

A series of laboratory experiments were carried out to investigate the response of a bar-blocked, saltwedge estuary to the imposition of both steady freshwater inflows and transient inflows that simulate storm events in the catchment area or the regular water releases from upstream reservoirs. The trapped salt water forms a wedge within the estuary, which migrates downstream under the influence of the freshwater inflow. The experiments show that the wedge migration occurs in two stages, namely (i) an initial phase characterized by intense shear-induced mixing at the nose of the wedge, followed by (ii) a relatively quiescent phase with significantly reduced mixing in which the wedge migrates more slowly downstream.

Provided that the transition time t_T between these two regimes satisfies t_T>g′h⁴L/q³α, as was the case for all our experiments and is likely to be the case for most estuaries, then the transition occurs at time t_T=1.2(gα³L⁶/g′³q²)^1/6, where g′=g&Delta;ρ/ρ0 is the reduced gravity, g the acceleration due to gravity, &Delta;ρ the density excess of the saline water over the density ρ₀ of the freshwater, q the river inflow rate per unit width, and L and α are the length and bottom slope of the estuary, respectively.

A simple model, based on conversion of the kinetic energy of the freshwater inflow into potential energy to mix the salt layer, was developed to predict the displacement xw over time t of the saltwedge nose from its initial position. For continuous inflows subject to t<t_T, the model predicts the saltwedge displacement as x_w/h=1.1 (t/&tau;)^1/3, where the normalizing length and time scales are h=(q²/g)^1/3 and &tau;=g′α²h4L/q³, respectively. For continuous inflows subject to t>tT, the model predicts the displacement as xw/h=0.45N1/6(t/&tau;)1/6/α, where N=q²/g′h²L is a non-dimensional number for the problem. This model shows very good agreement with the experiments. For repeated, pulsed discharges subject to t<t_T, the saltwedge displacement is given by (xw/h)3−(x0/h)(xw/h)2=1.3t/&tau;, where x₀ is the initial displacement following one discharge event but prior to the next event. For pulsed discharges subject to t>t_T, the displacement is given by (xw/h)⁶−(x0/h)(xw/h)⁵=0.008N(t/&tau;)/α⁶. This model shows very good agreement with the experiments for the initial discharge event but does systematically underestimate the wedge position for the subsequent pulses. However, the positional error is less than 15%.

Blind source separation based on phase and frequency redundancy of cyclostationary signals

This paper presents a new method for blind source separation by exploiting phase and frequency redundancy of cyclostationary signals in a complementary way. It requires a weaker separation condition than those methods which only exploit the phase diversity or the frequency diversity of the source signals. The separation criterion is to diagonalize a polynomial matrix whose coefficient matrices consist of the correlation and cyclic correlation matrices, at time delay .TAU. = 0, of multiple measurements. An algorithm is proposed to perform the blind source separation. Computer simulation results illustrate the performance of the new algorithm in comparison with the existing ones.

The Australasian triage scale: examining emergency department nurses' performance using computer and paper scenarios

Study objective: The purpose of this study is to examine emergency nurses' performance using triage scenarios characterized by type of patient population (adult versus pediatric) and mode of delivery (paper versus computer). Methods:   A combination of paper-based (script alone) and computer-based (script plus still photographs) triage scenarios were used. Of the 28 scenarios used, half were written and half were computer based. Within each subgroup, there were 7 adult and 7 pediatric scenarios. Participants were asked to allocate an Australasian Triage Scale category for each triage scenario. Results: One hundred sixty-seven participants completed a total of 2,349 adult scenarios, and 161 participants completed 2,265 pediatric scenarios. Sixty-one percent of the triage decisions made by the nurses were “expected” triage decisions, 18% were “undertriage,” decisions, and 21% were “overtriage” decisions. Nurse triage allocation decisions for the scenarios containing still photographs delivered by computer demonstrated a higher average agreement percentage of 66.2% (κ=0.56; &tau;b=0.77; P<.0001) compared with the average agreement percentage of 55.4% (κ=0.42; &tau;b=0.75; P<.0001) using paper-based (text-only) scenarios. Conclusion: The mode of delivery appeared to have an effect on the nurses' triage performance. It is unclear whether the use of simple still photographs used in the computer mode of delivery resulted in a higher incidence of expected triage decisions and, thus, improved performance. The use of cues such as photographs and video footage to enhance the fidelity of triage scenarios may be useful not only for the education of triage nurses but also the conduct of research into triage decisionmaking. However, further exploration and research in this area are warranted.

Educational partnerships on-line: global collaborative learning through an on-line student exchange programme

Deakin University and the University of Calgary have used the internet to provide workplace-based learners with the possibility of a student exchange programme which does not disrupt their careers, lives or families.  The programmes involved in this on-line exchange were both developed in response to the needs of workplace learners and are representative of the role of universities in the field of life-long learning.  This paper describes the first phase of the exchange and discusses the shared pedagogical philosophies and shared implementation of on-line groupware which provided a rationale for the exchange.  The paper will explore the cross-cultural implications of the educational experience and the possibilities such an exchange opens up for life-long learners.

Meaningful UDDI web services description

There is a lack of meaningful description of Web Services in UDDI, however, it is necessary for automatic services discovery. In this paper, a language is proposed for semantics description of Web Services which complements the UDDI standards to derive relationships among Web Services. The semantics description can be used to automatically derive relationships among Web Services. We describe how the semantics description of Web Services, based on the proposed language, can be integrated with UDDI.