Structural relaxation in the hydrogen-bonding liquids N-methylacetamide and water studied by optical Kerr-effect spectroscopy

Structural relaxation in the peptide model N-methylacetamide (NMA) is studied experimentally by ultrafast optical Kerr-effect spectroscopy over the normal-liquid temperature range and compared to the relaxation measured in water at room temperature. It is seen that in both hydrogen-bonding liquids, beta relaxation is present and in each case it is found that this can be described by the Cole-Cole function. For NMA in this temperature range, the alpha and beta relaxations are each found to have an Arrhenius temperature dependence with indistinguishable activation energies. It is known that the variations on the Debye function, including the Cole-Cole function, are unphysical, and we introduce two general modifications: one allows for the initial rise of the function, determined by the librational frequencies, and the second allows the function to be terminated in the alpha relaxation

Quality Control in the Office Laboratory

First, how can the quality of the office laboratory be assured and documented? Second, how can this information be disseminated to legislators and the general public? The first is an easily solved technical problem toward which this paper is directed. The second and probably the most difficult is a media problem beyond the scope of a technical journal

‘’It takes me half a bottle of whisky to get through one of your assignments’’: Exploring one teacher educators personal experiences of dyslexia’

This article uses a life history approach to explore personal experiences of dyslexia of one higher education lecturer and its impact on her professional identity. The informant is currently employed as a lecturer of initial teacher training in a UK university. She worked as a primary school teacher for over a decade prior to embarking on an academic career in teacher education. The informant draws on her own experiences as a pupil, teacher and lecturer and additionally she presents accounts of student teachers with dyslexia drawn from her current professional context. Although the data is not generalisable, the account nevertheless illustrates the positive impact of the social model of disability for the informant and her students who had been identified as dyslexic during their in initial training as teachers. Additionally, the account also illustrates the ways in which teachers’ personal experiences of dyslexia can shape professional identities in very positive ways. Implications for both teacher training and pedagogic approaches in schools to support learners with dyslexia are drawn out of the narrative

Critique of Two Methods for Assessing the Nutrient Adequacy of Diets

The adequacy of diets can be assessed using several analytical approaches. This paper reviews two methods of assessment: a cutoff method, which estimates the percentage of the population having usual intakes below a given value; and a probability method, which assesses the percentage of the population whose usual intakes are below their individual requirements. First, the concept of usual nutrient intakes and the problems associated with estimating usual intake distributions are discussed. Next, the two methods of dietary assessment and their related assumptions are described and compared. The more specific inference of the probability method is shown to rely on its assumptions and data that are currently not available. While the cutoff method is simpler, its use may result in misclassification errors and its estimates are highly influenced by the cut-off standard selected.

Development of a low-maintenance measurement approach to continuously estimate methane emissions: a case study

The chemical breakdown of organic matter in landfills represents a significant source of methane gas (CH4). Current estimates suggest that landfills are responsible for between 3% and 19% of global anthropogenic emissions. The net CH4 emissions resulting from biogeochemical processes and their modulation by microbes in landfills are poorly constrained by imprecise knowledge of environmental constraints. The uncertainty in absolute CH4 emissions from landfills is therefore considerable. This study investigates a new method to estimate the temporal variability of CH4 emissions using meteorological and CH4 concentration measurements downwind of a landfill site in Suffolk, UK from July to September 2014, taking advantage of the statistics that such a measurement approach offers versus shorter-term, but more complex and instantaneously accurate, flux snapshots. Methane emissions were calculated from CH4 concentrations measured 700 m from the perimeter of the landfill with observed concentrations ranging from background to 46.4 ppm. Using an atmospheric dispersion model, we estimate a mean emission flux of 709 μg m−2 s−1 over this period, with a maximum value of 6.21 mg m−2 s−1, reflecting the wide natural variability in biogeochemical and other environmental controls on net site emission. The emissions calculated suggest that meteorological conditions have an influence on the magnitude of CH4 emissions. We also investigate the factors responsible for the large variability observed in the estimated CH4 emissions, and suggest that the largest component arises from uncertainty in the spatial distribution of CH4 emissions within the landfill area. The results determined using the low-maintenance approach discussed in this paper suggest that a network of cheaper, less precise CH4 sensors could be used to measure a continuous CH4 emission time series from a landfill site, something that is not practical using far-field approaches such as tracer release methods. Even though there are limitations to the approach described here, this easy, low-maintenance, low-cost method could be used by landfill operators to estimate time-averaged CH4 emissions and their impact downwind by simultaneously monitoring plume advection and CH4 concentrations

Introduction to integrated environmental modelling to solve real world problems: methods, vision and challenges

Across the world, stakeholders are asking questions of their governments and decision makers to quantify the risks of environmental threats to their well-being. These questions manifest themselves as ‘deceptively simple questions’, which are easy to articulate but difficult to solve. An example of which is: ‘how much will the eruption of an Icelandic volcano cost the UK economy’. Answering these questions requires predictions of the interaction of multiple environmental processes, this requires the development and maintenance of systems that allow these processes to be simulated, and that is the nascent science of integrated environmental modelling (IEM). Such processes may be long-term (e.g. those that are impacted by climate change) or short-term threats, such as the impact of drought on UK agriculture or the impact of space weather on energy supply systems

A Simple, Quick, and Precise Procedure for the Determination of Water in Organic Solvents

A procedure for the UV/VIS-spectroscopic determination of water by the use of a solvatochromic pyridiniumphenolate betaine is given. The water content of organic solvents is calculated by a two parameter equation from λmax of the dye. A typical, detection limit is of the order of 1 mg in 1 ml solvent for routine spectrometers. The parameters for the determination of water are given for a number of commonly used solvents

Multiscale Analysis of Delamination of Carbon Fiber-Epoxy Laminates with Carbon Nanotubes

A multi-scale analysis is presented to parametrically describe the Mode I delamination of a carbon fiber/epoxy laminate. In the midplane of the laminate, carbon nanotubes are included for the purposes of selectively enhancing the fracture toughness of the laminate. To analyze carbon fiber epoxy carbon nanotube laminate, the multi-scale methodology presented here links a series of parameterizations taken at various length scales ranging from the atomistic through the micromechanical to the structural level. At the atomistic scale molecular dynamics simulations are performed in conjunction with an equivalent continuum approach to develop constitutive properties for representative volume elements of the molecular structure of components of the laminate. The molecular-level constitutive results are then used in the Mori-Tanaka micromechanics to develop bulk properties for the epoxy-carbon nanotube matrix system. In order to demonstrate a possible application of this multi-scale methodology, a double cantilever beam specimen is modeled. An existing analysis is employed which uses discrete springs to model the fiber bridging affect during delamination propagation. In the absence of empirical data or a damage mechanics model describing the effect of CNTs on fracture toughness, several tractions laws are postulated, linking CNT volume fraction to fiber bridging in a DCB specimen. Results from this demonstration are presented in terms of DCB specimen load-displacement responses

Improving the discovery and re-use of hazard models – the PURE Portal

The Probability Uncertainty and Risk in the Environment (PURE) network is an action that has been prioritised by NERC in order to increase the impact of NERC Natural Hazards Research and to take a national leadership role in changing the way in which uncertainty and risk are assessed and quantified across the natural hazards community. Running in parallel with the PURE research programme a requirement was identified by the PURE project board to increase the level of sharing and re-use of hazard models. This provides an important knowledge exchange facility and help to ensure maximum exposure for NERC funded models. The PURE portal consists of a web interface underpinned by a model metadata database. Whilst there are many metadata catalogues and repositories for spatial data sets, e.g. data.gov.uk, the same is not the case for process models. Zaslavsky et al (2014) review five existing ones which mainly contain model codes, examples include the US-based CSDMS model catalogue (Peckham et al., 2014) and the TESS model funded by the EU which was created to store metadata for ecosystem management. In the UK, the FluidEarth 2 catalogue holds metadata on linkable models (Harpham et al., 2014). The PURE portal is specifically designed to hold metadata for both model code and model instance for Hazard models and their implementations created within the research community