Trace element geochemistry in the earliest terrestrial ecosystem, the Rhynie Chert

Acknowledgements JGTA is supported by the Natural Environment Research Council (grant NE/T003677/1). Samples were archived at the University of Aberdeen by N.H. Trewin, S.R. Fayers and C.M. Rice. Skilled technical support was provided by J. Johnston, J. Bowie, W. Ritchie and C. Taylor. We are grateful for the comments of two reviewers which improved the manuscript.Peer reviewedPublisher PD

SPCal - An open source, easy-to-use processing platform for ICP-TOFMS based single event data

Single particle inductively coupled plasma – mass spectrometry (SP ICP-MS) has evolved into one of the most powerful techniques for the bottom-up characterisation of nanoparticle suspensions. The latest generations of time-of-flight mass analysers offer new perspectives on single particles by rapidly collecting full mass spectra and providing information on particle composition and abundances even in unknown samples. However, SP ICP-TOFMS is associated with vast data sizes with complex structure, which can hamper its applicability and the interrogation of specific particle features. Unlocking the full potential of SP ICP-TOFMS requires dedicated, easy-to-use software solutions to navigate through data sets and promote transparent, efficient and precise processing. SPCal is an open-source SP data processing platform, which we have previously released for quadrupole-based data. In this work, we expand its reach by enabling the analysis of TOF-based SP data sets additionally. We have incorporated various tools to facilitate the handling, manipulation and calibration of large data sets and provide the required statistical fundament and models to promote accurate thresholding. Non-target screening tools are integrated to pinpoint particulate elements in unknown samples without the requirement for a-priori investigations or modelling. Next to basic functions like the calibration of size and mass distributions, methods to carry out cluster analysis (PCA, HAC) provide the means to study groups of particles based on their composition and conditional data filtering allows the interrogation of particle populations by selectecting specific features

Computer-Supported Cooperative Work: The Journal of Collaborative Computing Special Issue of CSCW on activity theory and design

Steps across the border – Cooperation, knowledge production and systems design The computer support of cooperation and knowledge production across socially distributed activity systems has become an important topic in the context of the discourse on "knowledge management". The present article will draw on concepts of cultural-historical activity theory to discuss the problem of how the notion of "knowledge " is conceptualized and implicitly implemented in computer systems to support knowledge management, often neglecting the social embeddedness of knowledge production in everyday work practices. From the point of view of cultural-historical activity theory we would propose to look upon the generation of knowledge as a process embedded in socially distributed activities that are constantly being reproduced and transformed in and between specific communities of practice. We will present a model of cooperation that relates processual and structural aspects of joint activity. Methodologically, it draws on the analysis of unexpected events in the course of joint activity. Our model also proposes to use forums for co-construction to make visible different perspectives in the process of software design. The concept of cooperative model production is highlighted as a means to mediate, not to eliminate, differences of perspectives involved in the course of systems design. An empirical example will be given in which the repertory-grid technique is used to visualize similarities and differences of potential users ’ viewpoints and requirements in early stages of systems design

Fluorine mapping via LA-ICP-MS/MS : a proof of concept for biological and geological specimens

Funding Information: The authors acknowledge the financial support by the University of Graz. Publisher Copyright: © 2023 The Royal Society of Chemistry.Peer reviewedPublisher PD

Applications of liquid chromatography-inductively coupled plasma-mass spectrometry in the biosciences: A tutorial review and recent developments

The biological function of minor and trace elements is ordinarily determined by their association with specific proteins, peptides and other biomolecules. Therefore, measuring the total elemental content of a biological sample provides limited information, particularly when a specific effect is due to an individual metal-protein complex. Speciation of metalloproteins, heteroatom-containing molecules or other compounds tagged with an exogenous metal can be used to overcome this limitation. A range of chromatographic separation techniques with on-line elemental detection using inductively coupled plasma-mass spectrometry (ICP-MS) have been applied to the biosciences, and each technique has intrinsic features that must be considered when designing speciation experiments. This tutorial review provides an overview of speciation in the biosciences, highlighting the unique abilities and limitations encountered. A selection of recent technical advances and new applications, the challenges of sample preparation and implementation of new technical developments are discussed, as well as the future directions of technology that is rapidly gaining a foothold in the contemporary biochemistry laboratory

Strategies to enhance figures of merit in ICP-ToF-MS

Inductively coupled plasma with time-of-flight mass spectrometry (ICP-ToF-MS) is currently setting new benchmarks for the analysis of single particles (SP) and elemental mapping using laser ablation (LA). The rapid collection of the full elemental mass spectra promotes non-target approaches, fast imaging as well as inquiries of particle stoichiometry. However, one shortcoming often associated with ICP-ToF-MS is a lack of detection power due to lower duty cycles relative to sequentially operating mass analysers. The sensitivity of ICP-ToF-MS can be increased using two strategies, which are detailed in this study. First, instead of analysing full mass spectra, elements in the low and high mass range were excluded from analysis using a Bradbury-Nielsen gate. The resulting restricted mass range was acquired up to 5 times faster increasing duty cycles and sensitivity accordingly. Second, isotopes of polyisotopic elements recorded simultaneously were accumulated to increase signal to noise ratios. In a proof of concept, we applied SP ICP-ToF-MS for the first time for the characterisation of upconversion nanoparticles (UCNPs) which contained Gd and Yb. Both signal amplification strategies were combined and the consequences for detection limits and signal to noise ratios were considered and compared to a standard method. Sensitivities were increased up to factor 27 when accumulating all Gd and Yb isotopes at 177 kHz, and size detection limits decreased by a factor of approximately 3. Improved figures of merit promoted more accurate investigations of UCNPs, which were characterised regarding size distributions and composition. As second application, we demonstrated the utility of the described strategies in LA-ICP-ToF-MS. Mo and Se were targeted as relatively rare elements in rat brain tissue. Increased acquisition frequencies of 185 kHz and isotope accumulation resulted into drastically improved signal to noise ratios and enabled the mapping of both while still considering relevant neuroanatomical elements such as Fe and Zn

AF4-MALS-SP ICP-ToF-MS analysis gives insight into nature of HgSe nanoparticles formed by cetaceans.

Cetaceans are known to accumulate very high levels of mercury (Hg) and unlike fish species, most of the mercury is not present as methylmercury (MeHg) but instead as inorganic Hg. It has been suggested this is a result of a detoxification process which involves the sequestering of Hg by Se-containing proteins, concluding with the formation of HgSe nanoparticles. However, their elemental compositions besides Hg and Se, as well as their genesis are unknown. We applied asymmetric flow-field flow fractionation - multiangle laser light scattering (AF4 -MALS) coupled to single particle inductively coupled plasma - time of flight - mass spectrometry (SP ICP-ToF-MS) for the size-dependant separation, counting and further elemental characterisation of of Hg/Se-containing nanoparticles in the liver and cerebellum of a sperm whale. Using a proteinase K digestion method, we isolated and identified particles which had size-independent masses of Hg and as well as a continuous molar ratio of Hg to Se. We also identified Cd and Sn on particles alongside Hg and Se, which indicated the detoxification process resulting in Hg/Se nanoparticles may not be specific to MeHg. This data indicates nanoclusters of toxic elements, bound to selenium, make up a nanoparticle core which is surrounded by a larger non-metal(loid) corona

Optofluidic Force Induction meets Raman Spectroscopy and Inductively Coupled Plasma – Mass Spectrometry: A new hyphenated technique for comprehensive and complementary characterisations of single particles

Nanoparticles are produced at accelerating rates, are increasingly integrated in scientific and industrial applications, and are widely discharged into the environment. Analytical techniques are required to characterise parameters such as particle number concentrations, mass and size distributions, molecular and elemental compositions as well as particle stability. This is not only relevant to investigate their utility for various industrial or medical applications and for controlling the manufacturing processes, but also to assess toxicity and environmental fate. Different analytical strategies aim to characterise certain facets of particles but are difficult to combine to provide a more comprehensive picture. In this work, we suggest the on-line hyphenation of optofluidic force induction (OF2i) with Raman spectroscopy and inductively coupled plasma-time-of-flight-mass spectrometry (ICP-ToF-MS) to harness their complementary technology-specific advantages and to promote comprehensive particle characterisations. We optically trapped individual particles on a weakly focussed vortex laser beam by aligning a microfluidic flow antiparallelly to the laser propagation direction. The position of particles in this optical trap depended on the hydrodynamic diameter and therefore enabled size calibration. Additionally, laser light scattered on particles was analysed in a single particle (SP) Raman spectroscopy set-up for the identification of particulate species and phases. Finally, particles were characterised regarding elemental composition and their distributions in mass and size using SP ICP-ToF-MS. In a proof of concept, we analysed polystyrene-based plastic and TiO2 particles, and demonstrated the opportunities provided through OF2i-Raman-SP ICP-ToF-MS as new hyphenated technique

Porous upconversion nanostructures as bimodal biomedical imaging contrast agents

Lanthanide ion doped upconversion nanoparticles (UCNPs) hold great promise as multimodal contrast agents for a range of medical imaging techniques, including optical bioimaging (OBI), magnetic resonance imaging (MRI), and computed tomography (CT). However, it is challenging to obtain UCNPs with both maximal contrast enhancement effects for both OBI and MRI simultaneously owing to the dilemma in the size of UCNPs. UCNPs in large dimensions contain more photonic Ln ions and less surface defects, which is favored for high luminescent emissions, while small UCNPs with high specific surface areas allow a higher proportion of paramagnetic Ln ions to be more accessible to water molecules, which offers enhanced contrast in MRI. In this work, we report the novel design of core-porous shell UCNPs with both high luminescent emissions and magnetic relaxivities as potential dual-modal contrast agents. The core-porous shell UCNPs were fabricated via the selective etching of the inert shell of NaYF4: 30%Gd at the active core of NaYF4: 20%Yb, 1%Er. Their morphology and composition were carefully characterized using transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy, X-ray diffraction, and high resolution TEM. Their photoluminescent and magnetic resonance properties were experimentally determined and compared for the core, core-dense shell, and core-porous shell UCNPs. Core-porous shell UCNPs were found to display bright luminescence and superior MRI contrast enhancement, thus showing great potential as bimodal OBI and MRI contrast agents