Electrochemistry reveals archaeological materials

The characterization of materials constituting cultural artefacts is a challenging step in their conservation, due to the object’s uniqueness and the reduced number of conservation institutes able to supply non-destructive analysis. We propose an alternative analytical tool, which combines accessibility (low cost and portable) and high sensitivity, based on electrochemical linear sweep voltammetry (LSV) with paraffin impregnated graphite electrode (PIGE). To investigate the composition of “white alloys” that certainly have been used as decoration on copper-based Roman fibulae, sampling was done very locally by gently rubbing the selected areas with the PIGE. LSV results evidence the presence of silver, lead, and tin, supporting the argument provided by typological analysis that these metals were used for decoration

Evolutionary morphology of trichomycterid catfishes: about hanging on and digging in

The catfi shes (Siluriformes) comprise a particularly diverse teleost clade, from a taxonomic, morphological, biogeographical, ecological and behavioural perspective. The Neotropical Trichomycteridae (the “parasitic” catfi shes) are emblematic of this diversity, including fi shes with some of the most specialized habits and habitats among teleosts (e. g. hematophagy, lepidophagy, miniaturization, fossorial habitats, altitudinal extremes). Relatively little information is available on general trichomycterid morphology, as most work so far has concentrated on phylogenetically informative characters, with little concern about general descriptive anatomy. In this paper we provide a synthesis of new and previously-available data in order to build a general picture of basal crown group trichomycterid morphology and of its main modifi cations. We focus on the evolutionary morphology in two relatively distal trichomycterid lineages, i. e. the hematophagous Vandelliinae and the miniature, substrate dwelling Glanapteryginae. New evidence is discussed in relation to the evolution of the opercular system as well as morphological modifi cations in miniature species exhibiting an interstitial life style

The OPFOS microscopy family: High-resolution optical-sectioning of biomedical specimens

We report on the recently emerging (Laser) Light Sheet based Fluorescence Microscopy field (LSFM). The techniques used in this field allow to study and visualize biomedical objects non-destructively in high-resolution through virtual optical sectioning with sheets of laser light. Fluorescence originating in the cross section of the sheet and sample is recorded orthogonally with a camera. In this paper, the first implementation of LSFM to image biomedical tissue in three dimensions - Orthogonal-Plane Fluorescence Optical Sectioning microscopy (OPFOS) - is discussed. Since then many similar and derived methods have surfaced (SPIM, Ultramicroscopy, HR-OPFOS, mSPIM, DSLM, TSLIM...) which we all briefly discuss. All these optical sectioning methods create images showing histological detail. We illustrate the applicability of LSFM on several specimen types with application in biomedical and life sciences.Comment: 19 pages, 10 figures, to be published in Anatomical Research International (Hindawi

Ultrastructural Observations on Bacterial Invasion in Cementum and Radicular Dentin of Periodontally Diseased Human Teeth

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141124/1/jper0493.pd

Multivariate analysis of 3D ToF-SIMS images: method validation and application to cultured neuronal networks

Advanced data analysis tools are crucial for the application of ToF-SIMS analysis to biological samples. Here, we demonstrate that by using a training set approach principal components analysis (PCA) can be performed on large 3D ToF-SIMS images of neuronal cell cultures. The method readily provides access to sample component information and significantly improves the images’ signal-to-noise ratio (SNR)

Computational modelling of cancerous mutations in the EGFR/ERK signalling pathway

This article has been made available through the Brunel Open Access Publishing Fund - Copyright @ 2009 Orton et al.BACKGROUND: The Epidermal Growth Factor Receptor (EGFR) activated Extracellular-signal Regulated Kinase (ERK) pathway is a critical cell signalling pathway that relays the signal for a cell to proliferate from the plasma membrane to the nucleus. Deregulation of the EGFR/ERK pathway due to alterations affecting the expression or function of a number of pathway components has long been associated with numerous forms of cancer. Under normal conditions, Epidermal Growth Factor (EGF) stimulates a rapid but transient activation of ERK as the signal is rapidly shutdown. Whereas, under cancerous mutation conditions the ERK signal cannot be shutdown and is sustained resulting in the constitutive activation of ERK and continual cell proliferation. In this study, we have used computational modelling techniques to investigate what effects various cancerous alterations have on the signalling flow through the ERK pathway. RESULTS: We have generated a new model of the EGFR activated ERK pathway, which was verified by our own experimental data. We then altered our model to represent various cancerous situations such as Ras, B-Raf and EGFR mutations, as well as EGFR overexpression. Analysis of the models showed that different cancerous situations resulted in different signalling patterns through the ERK pathway, especially when compared to the normal EGF signal pattern. Our model predicts that cancerous EGFR mutation and overexpression signals almost exclusively via the Rap1 pathway, predicting that this pathway is the best target for drugs. Furthermore, our model also highlights the importance of receptor degradation in normal and cancerous EGFR signalling, and suggests that receptor degradation is a key difference between the signalling from the EGF and Nerve Growth Factor (NGF) receptors. CONCLUSION: Our results suggest that different routes to ERK activation are being utilised in different cancerous situations which therefore has interesting implications for drug selection strategies. We also conducted a comparison of the critical differences between signalling from different growth factor receptors (namely EGFR, mutated EGFR, NGF, and Insulin) with our results suggesting the difference between the systems are large scale and can be attributed to the presence/absence of entire pathways rather than subtle difference in individual rate constants between the systems.This work was funded by the Department of Trade and Industry (DTI), under their Bioscience Beacon project programme. AG was funded by an industrial PhD studentship from Scottish Enterprise and Cyclacel

Opal-CT precipitation in a clayey soil explained by geochemical transport model of dissolved Si (Blégny, Belgium)

Opal-CT precipitation controlling dissolved Si export Dissolved Si (DSi) exported by rivers are controlled by geological, hydrological and biological cycle processes [1]. The DSi concentrations measured in a river of an upstream catchment in eastern Belgium (Blégny, Land of Herve) don’t vary seasonally (6.91±0.94mgL-1; n=363). Si concentrations in pore water are often higher and vary more (8.65±3.65mgL-1; n=128). The decrease of DSi along the flowpath of water is due to sink processes, i.e. precipitation, adsorption or uptake by vegetation. As the DSi in the river does not show any seasonal variation, uptake by vegetation can be ruled out [1] whereas precipitation or adsorption can control the DSi drained by the stream water. This hypothesis is confirmed by XRD and DeMaster analysis. At 0.1m depth the soil is constituted of 62% quartz, 7% K-feldspar, 6% plagioclase, 3.2% carbonates, 18.9% Al-clay, 1.47% Kaolinite, 0.63% Chlorite and 0.2% amorphous Si, probably of biogenic origin. At 1.5m depth, the amounts of several minerals (35.8% quartz, 0.6% K-feldspars, 0.9% plagioclase, Al-clay 14.7%) drop drastically. Carbonates, chlorite and kaolinite are absent whereas 40.4% opal-CT appears. The precipitation of opal-CT controls the DSi export of this catchment. Development of geochemical transport model To descripe DSi export from a catchment a geochemical transport model is developped in HP1 which couples the water flux model Hydrus with the geochemical model PHREEQC [2]. Our model is based on the conceptual model developped in [3]. First results show different DSi export dynamics in the unsaturated zone than in the aquifer due to different pCO2 values and varying soil moisture conditions. Further development of the model will help to find out the reason of opal-CT precipitation in this setting. [1]Fulweiler, Nixon (2005) Biogeochemistry 74:115–130. [2] Simunek, Jacques, van Genuchten, Mallants (2006) JAWRA 42:1537-1547. [3] Ronchi et al. (2013). Silicon, 5(1), 115–133

Grain Surface Models and Data for Astrochemistry

AbstractThe cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of ∼25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions