Learning how much about gases using MBL? A case study from a chemistry classroom

Chemistry learning with understanding is a challenge. From a social constructivist position we view students ‘chemistry learning from experiments as involving the shared negotiation of meaning that uses experimental data to confirm or challenge their existing scientific theories. This study investigated teaching and learning practices related to the use of MBL in a high school chemistry laboratory where students were studying gases and kinetic theory. Given the widely accepted view that the use of such technology is a ‘cure-all’ for educational problems, the learning of students as a consequence of their use of this technology might be considered disappointing. We find that little or no higher order thinking was employed as students engaged in using the MBL and that some alternative conceptions remained unchallenged through its use. It is necessary to consider the positioning of the computer in the group and experimental context if the promise of the use of such technology is to be fulfilled.published_or_final_versio

Temperature-dependent Raman linewidths in transition-metal dichalcogenides

This is the author accepted manuscript. The final version is available from American Physical Society via the DOI in this recordUsing a semi-ab-initio theoretical method we examine the temperature-dependent linewidth of the Raman modes in bulk and monolayer transition-metal dichalcogenides (TMDs) MoS2, WS2, and MoTe2. It is found that different Raman modes show different linewidths and different temperature dependencies with respect to each other for a given sample and across different TMDs. We explain these characteristics as arising from a combination of phonon density of states, Raman mode frequency, and the relative contributions of temperature-independent mass-defect scattering and temperature-dependent intrinsic anharmonic interactions. Reported measurements for samples prepared under experimental conditions have been explained by adding frequency-dependent inhomogeneity-related background contribution to our theoretical results for the pure and homogeneous samples.This work has been possible with funds from the Leverhulme Trust (UK) through Grant No. RPG-2016-186, which provided financial support to I.O.T. and purchase of computer nodes for carrying out numerical calculations. Calculations were performed on the Ceres cluster at the University of Exeter

Extension of the modified effective medium approach to nanocomposites with anisotropic thermal conductivities

This is the author accepted manuscript. The final version is available from American Physical Society via the DOI in this recordAn extended modification of the effective medium approach (emEMA) has been developed for the thermal conductivity of anisotropic nanocomposites. This is based on extending approaches developed to treat an anisotropic particle insert and host matrix in electromagnetism of composites to anisotropic thermal interface resistance, with the inclusion of insert size and interface boundary density effects. The method has been applied to the case of spherical inclusions of the 2H dichalcodenide WS2 within a matrix of 2H MoS2, with input bulk thermal conductivities calculated using our recently developed semi-ab initio method. We find that the overall effects of anisotropy are strongest for small particles, but that as particle size increases, the surface anisotropy effects become more apparent.This work was supported by Leverhulme Trust (UK) Grant No. RPG-2016-186

The LIM and SH3 domain protein family: structural proteins or signal transducers or both?

LIM and SH3 Protein 1 (LASP-1) was initially identified from a cDNA library of metastatic axillary lymph nodes (MLN) more than a decade ago. It was found to be overexpressed in human breast and ovarian cancer and became the first member of a newly defined LIM-protein subfamily of the nebulin group characterized by the combined presence of LIM and SH3 domains. LASP2, a novel LASP1-related gene was first identified and characterized in silico. Subsequently it proved to be a splice variant of the Nebulin gene and therefore was also termed LIM/nebulette. LASP-1 and -2 are highly conserved in their LIM, nebulin-like and SH3 domains but differ significantly at their linker regions. Both proteins are ubiquitously expressed and involved in cytoskeletal architecture, especially in the organization of focal adhesions. Here we present the first systematic review to summarize all relevant data concerning their domain organization, expression profiles, regulating factors and function. We compile evidence that both, LASP-1 and LASP-2, are important during early embryo- and fetogenesis and are highly expressed in the central nervous system of the adult. However, only LASP-1 seems to participate significantly in neuronal differentiation and plays an important functional role in migration and proliferation of certain cancer cells while the role of LASP-2 is more structural. The increased expression of LASP-1 in breast tumours correlates with high rates of nodal-metastasis and refers to a possible relevance as a prognostic marker

Persistence of perennial ryegrass, tall fescue and cocksfoot following annual sowings: Influence of grass species, ryegrass cultivar and pasture age on yield, composition and density

Persistence is an important component of perennial pasture-grass productivity. Defining traits that affect persistence is essential for improving pasture longevity through plant breeding and for identifying persistence traits that should be included in cultivar ranking indices. Compared with conventional longitudinal studies, where a single sowing is monitored over time, repeated annual sowings allow the effects on persistence of sowing year and the ensuing interactions between environment and age of pasture to be identified. An experiment was commenced in 2015 under sheep grazing in Canterbury and in 2016 under cattle grazing in Waikato, where eight cultivars of perennial ryegrass representing different ploidy, flowering date, and cultivar age (release date), and one cultivar each of tall fescue and cocksfoot were sown in four randomised complete blocks in autumn each year. This paper reports interim data on spring and autumn pasture yield, composition, and density of 3-year-old, 2-year-old and 1-year-old pastures exposed to the same environmental conditions within the same, single year. There were significant effects on yield, botanical composition, basal cover and tiller density due to cultivar, pasture age, and their interaction. When the confounding effect of year-to-year variation was removed by comparing each age cohort in the same year, the underlying differences among grass species and cultivars, and ages of pasture, is starting to reveal the nature of this influence on pasture persistence

Tunable thermal transport characteristics of nanocomposites

This is the final version. Available from the publisher via the DOI in this record.We present a study of tunable thermal transport characteristics of nanocomposites by employing a combination of a full-scale semi-ab inito approach and a generalised and extended modification of the effective medium theory. Investigations are made for planar superlattices (PSLs) and nanodot superlattices (NDSLs) constructed from isotropic conductivity covalent materials Si and Ge, and NDSLs constructed from anisotropic conductivity covalent-van der Waals materials MoS2 and WS2 . It is found that difference in the conductivities of individual materials, period size, volume fraction of insertion, and atomic-level interface quality are the four main parameters to control phonon transport in nanocomposite structures. It is argued that the relative importance of these parameters is system dependent. The equal-layer thickness Si/Ge PSL shows a minimum in the room temperature conductivity for the period size of around 4 nm, and with a moderate amount of interface mass smudging this value lies below the conductivity of SiGe alloy.Leverhulme Trus

Behavioural responses of reptile predators to invasive cane toads in tropical Australia

The ecological impact of an invasive species can depend on the behavioural responses of native fauna to the invader. For example, the greatest risk posed by invasive cane toads (Rhinella marinaBufonidae) in tropical Australia is lethal poisoning of predators that attempt to eat a toad; and thus, a predator's response to a toad determines its vulnerability. We conducted standardized laboratory trials on recently captured (toad-naïve) predatory snakes and lizards, in advance of the toad invasion front as it progressed through tropical Australia. Responses to a live edible-sized toad differed strongly among squamate species. We recorded attacks (and hence, predator mortality) in scincid, agamid and varanid lizards, and in elapid, colubrid and pythonid snakes. Larger-bodied predators were at greater risk, and some groups (elapid snakes and varanid lizards) were especially vulnerable. However, feeding responses differed among species within families and within genera. Some taxa (notably, many scincid and agamid lizards) do not attack toads; and many colubrid snakes either do not consume toads, or are physiologically resistant to the toad's toxins. Intraspecific variation in responses means that even in taxa that apparently are unaffected by toad invasion at the population level, some individual predators nonetheless may be fatally poisoned by invasive cane toads. © 2013 Ecological Society of Australia