922017 research outputs found
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The interaction of multiple bubbles in a Hele-Shaw channel
No full textWe study the dynamics of two air bubbles driven by the motion of a suspending viscous fluid in a Hele-Shaw channel with a small elevation along its centreline via physical experiment and numerical simulation of a depth-averagedmodel. For a single-bubble systemwe establish that, in general, bubble propagation speed monotonically increases with bubble volume so that two bubbles of different sizes, in the absence of any hydrodynamic interactions, will either coalesce or separate in a finite time. However our experiments indicate that the bubbles interact and that an unstable two-bubble state is responsible for the eventual dynamical outcome: coalescence or separation. These results motivate us to develop an edge-tracking routine and calculate these weakly unstable two-bubble steady states from the governing equations. The steady states consist of pairs of ‘aligned’ bubbles that appear on the same side of the centreline with the larger bubble leading. We also discover, through time-dependent simulations and physical experiment, another class of two-bubble states that, surprisingly, are stable. In contrast to the ‘aligned’ steady states, these bubbles appear on either side of the centreline and are ‘offset’ from each other. We calculate the bifurcation structures of both classes of steady states as the flow-rate and bubble volume ratio is varied. We find that they exhibit intriguing similarities to the single-bubble bifurcation structure, which has implications for the existence of =-bubble steady states
Assessing Immunogenicity of Biologic Drugs in Inflammatory Joint Diseases: Progress Towards Personalized Medicine
No full textBiologic drugs have greatly improved treatment outcomes of inflammatory joint diseases (IJDs), but a substantial proportion of patients either do not respond to treatment or lose response over time. Drug immunogenicity, manifested as formation of anti-drug antibodies (ADAb), constitute a significant clinical problem. ADAb influence the pharmacokinetics of the drug, are associated with reduced clinical efficacy, and increased risk of adverse events such as infusion reactions. The prevalence of ADAb differ among drugs and diseases, and detection of ADAb also depends on assay format. Most data exist for the tumor necrosis factor alpha inhibitors infliximab and adalimumab, with a frequency of ADAb ranging from 10-60% across studies. Measurement of ADAb and serum drug levels, therapeutic drug monitoring (TDM), has been suggested as a strategy to optimize therapy with biologic drugs. Although the recent randomized clinical Norwegian Drug Monitoring (NOR-DRUM) trials show promise towards a personalized medicine prescribing approach by TDM, several challenges remain. A plethora of assay formats, with widely differing properties, is currently used for measuring ADAb. Comparing results between different assays and laboratories is difficult, which complicates development of cut-offs necessary for guidelines and implementation of ADAb measurements in clinical practice. With the possible exception of infliximab, limited data on clinical relevance and cost-effectiveness exist to support TDM as a routine clinical strategy to monitor biologic drugs in IJDs. The aim of this review is to provide an overview of the characteristics and prevalence of ADAb, predisposing factors to ADAb formation, commonly used assessment methods, clinical consequences of ADAb, and the potential implications of ADAb assessments for everyday treatment of IJDs
Synthesis and characterisation of an integratively self-sorted [Fe<sub>4</sub>L<sub>6</sub>]<sup>8+</sup> tetrahedron
No full textIsolating metal-organic cage structures which incorporate more than one distinct ligand has been challenging due to competing pressures from narcissistic and social sorting phenomena. Here we report the first example of exclusive formation of a single tetrahedral product from a reaction mixture containing two different bidentate ligands. Exclusive formation of the tetrahedron, which incorporates one unique metal vertex, relies on a triamine to orientate the heteroditopic ligand. Inclusion of perchlorate counterions during the self-assembly process is also found to be a requirement if social sorting is to be avoided. The C3-symmetric structure is characterised by HR-MS, NMR spectroscopy and X-ray crystallography, and provides proof of principle for use of heteroditopic ligands in classical M4L6 supramolecular structures, opening exciting possibilities for their use in separation, storage and catalysis applications
The reporting and methodological quality of split-mouth trials in oral implantology: A methodological study
No full textObjectives: To assess the reporting and methodological quality of split-mouth trials (SMTs) in oral implantology published during the past ten years, and to investigate whether there was any improvement over time.Materials and Methods: We searched PubMed for SMTs in oral implantology published during 2011-20. We used CONSORT 2010, its extension for within-person trial (WPT), and an SMT-specific methodological checklist to assess trial reporting quality (TRQ), WPT-specific reporting quality (WRQ), and SMT-specific methodological quality (SMQ), respectively. Binary scores were given to each item, and total scores of TRQ (range 0-32), WRQ (0-15), and SMQ (0-3) were calculated for each study. Multivariable regression analyses were performed to compare the quality of SMTs published before (2011-17) and after (2018-20) the release of CONSORT for WPT.Results: Seventy-nine SMTs were included. The mean TRQ, WRQ, and SMQ were 16.4, 6.7, and 1.3, respectively. Less than one-third (n=25, 31.6%) reported the rationale for using splitmouth designs. Only 4 (5.1%) trials adequately conducted sample size calculation, and 40 (50.6%) used appropriate statistical methods that considered dependency and clustering of data. In multivariable analyses, compared with 2011-17, studies published in 2018-20 had significantly higher TRQ (P = 0.044), while WRQ and SMQ did not show improvement.Conclusions: The reporting and methodological quality of SMTs in oral implantology need to be improved. Joint efforts are needed to improve the reporting and methodology of SMTs in this field
Finite element modelling of hot compression testing of titanium alloys
No full textThis paper presents experimental results and finite element analysis of hot upsetting of titanium alloys Ti64 and Ti407 using a dilatometer in loading mode. All samples showed barrelling, as a consequence of an inhomogeneous temperature distribution and friction. The FE analysis is a full thermomechanical model of the test calibrated using multiple thermocouples. At each nominal temperature and strain-rate, the true flow stress-strain response is inferred using the difference between the initially assumed constitutive response input to the FE analysis, 𝜎𝜎=𝑓𝑓(𝑇𝑇,𝜀𝜀˙,𝜀𝜀), and the predicted response of the model. The analysis applies new procedures for: (i) modelling the thermal gradient; (ii) finding the flow stress correction due to the inhomogeneity, using literature data as the input to the FE analysis; (iii) smoothing the constitutive data, fitting empirical 𝜎𝜎=𝑓𝑓(𝑇𝑇,𝜀𝜀˙) surfaces at multiple discrete strains. The extracted true constitutive data confirms the moderate strain-softening behaviour in Ti64 alloy, and the FE model predicts the distribution of local deformation conditions, for application in interpretation of microstructure and texture evolution. This highlights the difference between nominal and actual test conditions, showing that the discrepancy varies systematically with test conditions, with the central strain and strain-rate being magnified significantly, by factors of order 2–3
Long-term antibody response following COVID-19 vaccination in patients receiving peritoneal dialysis
No full textPeer-to-Peer, Community Self-Consumption, and Transactive Energy: A Systematic Literature Review of Local Energy Market Models
No full textPeer-to-peer, community or collective self-consumption, and transactive energy markets offer new models for trading energy locally. Over the past five years, there has been significant growth in the amount of academic literature examining how these local energy markets might function. This systematic literature review of 139 peer-reviewed journal articles examines the market designs used in these energy trading models. A modified version of the Business Ecosystem Architecture Modelling framework is used to extract market model information from the literature, and to identify differences and similarities between the models. This paper examines how peer-to-peer, community self-consumption and transactive energy markets are described in current literature. It explores the similarities and differences between these markets in terms of participation, governance structure, topology, and design. This paper systematises peer-to-peer, community self-consumption and transactive energy market designs, identifying six archetypes. Finally, it identifies five evidence gaps which require future research before these markets could be widely adopted. These evidence gaps are the lack of: consideration of physical constraints; a holistic approach to market design and operation; consideration about how these market designs will scale; consideration of information security; and, consideration of market participant privacy
Flash Sintering, A Novel Technique for Nuclear Waste Management
No full textMixed uranium plutonium oxide (MOx) pellets are a potential candidate wasteform for plutonium disposition in a GDF. However, to manufacture MOx pellets suitable for disposal, homogenised powder feeds must be densified by a sintering process. This is an energy intensive and time-consuming process. Flash Sintering (FS) is an innovative technique in which an electric field is applied to the sample during the sintering process. It offers a more efficient and robust way to densify ceramic-containing nuclear material for disposal. The FS process requires significantly lower firing temperatures. It may therefore offer safety improvements when immobilising unique or problematic waste streams, due to the retention of volatile but long-lived minor actinides such as americium oxide. These would normally vaporise out of the MOx pellet during the high temperatures and long hold times in conventional sintering.We report the successful application of controlled current rate AC-FS flash sintering on both UO2 and CeO2 surrogate nuclear material for both fuel and waste applications, together with the microstructural evolution of pellets produced using both conventional (CeO2) and FS (CeO2 and UO2). These results demonstrate the possibility of forming different microstructures as a function of current density, in a fraction of conventional processing time. Future opportunities exist for expanding this work to the demonstration of FS on mixed CeO2 and UO2, as well as zirconia and neutron poison-doped materials for waste management applications.<br/
The Winchcombe meteorite – a regolith breccia from a rubble-pile CM chondrite asteroid
No full textThe Winchcombe meteorite is a CM chondrite breccia composed of eight distinct lithological units plus a cataclastic matrix. The degree of aqueous alteration varies between intensely altered CM2.0 and moderately altered CM2.6. Although no lithology dominates, three heavily altered rock types (CM2.1- 2.3) represent >70 area%. Tochilinite-cronstedtite intergrowths (TCIs) are common in several lithologies. Their compositions can vary significantly, even within a single lithology, which can prevent a clear assessment of alteration extent if only TCI composition is considered. We suggest this is due to early alteration under localised geochemical microenvironments creating a diversity of compositions and because later reprocessing was incomplete, leaving a record of the parent body’s fluid history. In Winchcombe fragments of primary accretionary rock are held within a cataclastic matrix (~15 area%). This material is impact-derived fallback debris. Its grain size and texture suggest that the disruption of the original parent asteroid responded by intergranular fracture at grain size