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    59538 research outputs found

    Sodium doping and trapped ion mobility spectrometry improve lipid detection for novel MALDI-MSI analysis of oats

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    Oat (Avena sativa L.) is an important cereal grain with a unique nutritional profile including a high proportion of lipids. Understanding lipid composition and distribution in oats is valuable for plant, food and nutritional research, and can be achieved using MALDI mass spectrometry imaging (MALDI-MSI). However, this approach presents several challenges for sample preparation (hardness of grains) and analysis (isobaric and isomeric properties of lipids). Here, oat sections were successfully mounted onto gelatin-coated indium tin oxide slides with minimal tearing. Poor detection of triacylglycerols was resolved by applying sodium chloride during mounting, increasing signal intensity. In combination with trapped ion mobility spectrometry (TIMS), lipid identification significantly improved, and we report the separation of several isobaric and isomeric lipids with visualisation of their “true” spatial distributions. This study describes a novel MALDI-TIMS-MSI analytical technique for oat lipids, which may be used to improve the discovery of biomarkers for grain quality.Wai C.D. Lau, Leigh Donnellan, Matthew Briggs, Thusitha Rupasinghe, John C. Harris, Julie E. Hayes, Peter Hoffman

    The GABA shunt contributes to ROS homeostasis in guard cells of Arabidopsis

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    First published: 07 November 2023γ-Aminobutyric acid (GABA) accumulates rapidly under stress via the GABA shunt pathway, which has been implicated in reducing the accumulation of stress-induced reactive oxygen species (ROS) in plants. γ-Aminobutyric acid has been demonstrated to act as a guard-cell signal in Arabidopsis thaliana, modulating stomatal opening. Knockout of the major GABA synthesis enzyme Glutamate Decarboxylase 2 (GAD2) increases the aperture of gad2 mutants, which results in greater stomatal conductance and reduces water-use efficiency compared with wild-type plants. Here, we found that the additional loss of GAD1, GAD4, and GAD5 in gad2 leaves increased GABA deficiency but abolished the more open stomatal pore phenotype of gad2, which we link to increased cytosolic calcium (Ca2+ ) and ROS accumulation in gad1/2/4/5 guard cells. Compared with wild-type and gad2 plants, glutamate was ineffective in closing gad1/2/4/5 stomatal pores, whereas lowering apoplastic calcium, applying ROS inhibitors or complementation with GAD2 reduced gad1/2/4/5 guard-cell ROS, restored the gad2-like greater stomatal apertures of gad1/2/4/5 beyond that of wild-type. We conclude that GADs are important contributors to ROS homeostasis in guard cells likely via a Ca2+ -mediated pathway. As such, this study reveals greater complexity in GABA's role as a guard-cell signal and the interactions it has with other established signals.Bo Xu, Xueying Feng, Adriane Piechatzek, Shuqun Zhang, Kai R. Konrad, Johannes Kromdijk, Rainer Hedrich, and Matthew Gilliha

    Insights into the invasive diagnostic challenges of coronary artery vasospasm - A systematic review

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    Available online 3 August 2023Coronary provocation testing is an essential diagnostic procedure when evaluating vasospastic angina. Invasive methods using acetylcholine or ergonovine are considered the current gold standard. Despite efforts from global cardiovascular institutions, current protocols vary in dosage, administration time, and procedural approach. In addition, concerns over the specificity of findings and potential complications have limited routine uptake of this procedure in clinical practice. This systematic review evaluates current diagnostic protocols, focusing on invasive provocation testing. We included studies using intracoronary provocation testing with acetylcholine or ergonovine for the assessment of coronary artery vasospasm that detailed specific elements of the procedure (dosage, administration time, etc.) and included ≥50 patients. A total of 28 articles met strict inclusion criteria. Our review highlights the heterogeneity between current diagnostic protocols for invasive provocation testing. We believe standardization of a diagnostic protocol will encourage both current and future cardiologists to incorporate such procedures in the evaluation of variant angina.Rajan Rehan, John Beltrame, Andy Yon

    Current advances in imaging spectroscopy and its state-of-the-art applications

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    Imaging spectroscopy integrates traditional computer vision and spectroscopy into a single system and has gained widespread acceptance as a non-destructive scientific instrument for a wide range of applications. The current state of imaging spectroscopy spans diverse applications including but not limited to air-borne and ground-based computer vision systems. This paper presents the current state of research and industrial applications including precision agriculture, material classification, medical science, forensic science, face recognition and document image analysis, environment monitoring, and remote sensing, which can be aided through imaging spectroscopy. In this regard, we further discuss a comprehensive list of applications of imaging spectroscopy, pre-processing techniques, and spectral image acquisition systems. Likewise, publicly available databases and current software tools for spectral data analysis are also documented in this review. This review paper, therefore, could potentially serve as a reference and roadmap for people looking for literature, databases, applications, and tools to undertake additional research in imaging spectroscopy.Anam Zahra, Rizwan Qureshi, Muhammad Sajjad, Ferhat Sadak, Mehmood Nawaz, Haris Ahmad Khan, Muhammad Uzai

    Hydrogen addition to a commercial self-aspirating burner and assessment of a practical burner modification strategy to improve performance

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    Available online 5 July 2023The ability for existing burners to operate safely and efficiently on hydrogen-blended fuels is a primary concern for the many industries looking to adopt hydrogen as an alternative fuel. This study investigates the efficacy of increasing fuel injector diameter as a simple modification strategy to extend the hydrogen-blending limits before flashback. The collateral effects of this modification are quantified with respect to a set of key performance criteria. The results show that the unmodified burner can sustain up to 50 vol% hydrogen addition before flashback. Increasing the fuel injector diameter reduces primary aeration, allowing for stable operation on up to 100% hydrogen. The flame length, visibility and radiant heat transfer properties are all increased as a result of the reduced air entrainment with a trade-off reported for NOx emissions, where, in addition to the effects of hydrogen, reducing air entrainment further increases NOx emissions.Adam J. Gee, Douglas B. Proud, Neil Smith, Alfonso Chinnici, Paul R. Medwel

    Correlated twin-photon generation in a silicon nitride loaded thin film PPLN waveguide

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    Photon-pair sources based on thin film lithium niobate on insulator technology have a great potential for integrated optical quantum information processing. We report on such a source of correlated twin-photon pairs generated by spontaneous parametric down conversion in a silicon nitride (SiN) rib loaded thin film periodically poled lithium niobate (LN) waveguide. The generated correlated photon pairs have a wavelength centred at 1560 nm compatible with present telecom infrastructure, a large bandwidth (21 THz) and a brightness of ∼2.5 × 105 pairs/s/mW/GHz. Using the Hanbury Brown and Twiss effect, we have also shown heralded single photon emission, achieving an autocorrelation g (2) H (0) ≃ 0.04.Antoine Henry, David Barral, Isabelle Zaquine, Andreas Boes, Arnan Mitchell, Nadia Belabas, and Kamel Bencheik

    The role of genetic selection and climatic factors in the dispersal of anatomically modern humans out of Africa.

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    The evolutionarily recent dispersal of anatomically modern humans (AMH) out of Africa (OoA) and across Eurasia provides a unique opportunity to examine the impacts of genetic selection as humans adapted to multiple new environments. Analysis of ancient Eurasian genomic datasets (~1,000 to 45,000 y old) reveals signatures of strong selection, including at least 57 hard sweeps after the initial AMH movement OoA, which have been obscured in modern populations by extensive admixture during the Holocene. The spatiotemporal patterns of these hard sweeps provide a means to reconstruct early AMH population dispersals OoA. We identify a previously unsuspected extended period of genetic adaptation lasting ~30,000 y, potentially in the Arabian Peninsula area, prior to a major Neandertal genetic introgression and subsequent rapid dispersal across Eurasia as far as Australia. Consistent functional targets of selection initiated during this period, which we term the Arabian Standstill, include loci involved in the regulation of fat storage, neural development, skin physiology, and cilia function. Similar adaptive signatures are also evident in introgressed archaic hominin loci and modern Arctic human groups, and we suggest that this signal represents selection for cold adaptation. Surprisingly, many of the candidate selected loci across these groups appear to directly interact and coordinately regulate biological processes, with a number associated with major modern diseases including the ciliopathies, metabolic syndrome, and neurodegenerative disorders. This expands the potential for ancestral human adaptation to directly impact modern diseases, providing a platform for evolutionary medicine.Raymond Tobler, Yassine Souilmi, Christian D. Huber, and Alan Coope

    Pull-Out Creep of Hooked-End Fibre Embedded in Ultra-High-Performance Concrete

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    If the beneficial effects of fibre reinforcement are to be considered in design of ultra-high performance fibre reinforced concrete (UHPC) structure, an understanding of the long-term creep behaviour is essential. The flexural/ tensile properties of UHPC depend on the individual contribution of discrete fibres that control the overall tensile properties. The creep of UHPC therefore depends on the pull-out creep of individual fibres under sustained load. Very little research has been conducted on single steel fibre pull-out creep. To address this lack of understanding, the impacts of fibre embedment length, fibre embedment angle and sustained load on pull-out creep are investigated in this research. The outcomes of the research show that for hooked-end fibres, a change of embedment length does not significantly influence pull-out creep. The inclination angle (angle between loading axis and fibre-embedded axis) had a significant role in concrete breakage at the loading end (embedded end at loading side) which generally occurred during the application of sustained load. Therefore, the pull-out creep was influenced by the fibre inclination angle for concrete breakage during application of sustained load. Finally, as expected with an increase in load, fibre pull-out creep increased.Iftekhair Ibnul Bashar, Alexander Bonaparte Sturm, Phillip Visintin, Abdul Hamid Sheik

    Can low-income people afford life satisfaction? The modifying effect of personality traits, a cross-sectional study

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    OnlinePublThe aim was to investigate whether the "Big Five" personality traits modify the association between household income and life satisfaction (LF); and to evaluate the interaction and main effects of personality traits and income on LF. Data from the Dental Care and Oral Health Study (DCOHS, 2015–2016) was used for the cross-sectional study (n=3,475). Multivariable Poisson regression models (adjusted for demographics and health behaviours) assessed the effect of personality traits (measured using the Ten-Item Personality Inventory) on the association between income and LF (measured by the Satisfaction With Life Scale) using prevalence ratios (PRs). The Relative Excess Risk due to Interaction (RERI) was calculated to assess the direction of effect modification. Among low-income respondents, low LF was less prevalent in those with high personality trait scores than those with low scores. The difference in the prevalence of low LF by personality traits was greater between low versus high income for openness (11.4% vs 7.7%), agreeableness (12.3% vs 9.4%) and emotional stability (26.1% vs 20.2%) categories. The combined effects of low income and low scores for these traits on LF also exceeded the sum of their individual effects, as shown by their positive RERIs. The association between low income and low LF was modified by high openness, agreeableness and emotional stability scores. Findings suggest that psychological interventions for improving LF would be most beneficial in low-income groups.Mehrsa Zakershahrak Sergio Chrisopoulos, Liana Luzzi, Dandara Haag, David Brenna

    Debonding detection in FRP-strengthened concrete structures utilising nonlinear Rayleigh wave mixing

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    This paper reports an investigation on the use of Rayleigh wave mixing method for the debonding detection in concrete structures strengthened with externally bonded fibre-reinforced polymer (FRP) composite plates. A three-dimensional (3D) finite element model is developed to simulate the propagation of Rayleigh waves in FRPstrengthened concrete structures. In this model, the frequency domain of the transmitted waves shows the generation of second harmonics and combinational harmonics on account of debonding. The numerically simulated results are then experimentally validated with carbon fibre-reinforced polymer (CFRP)-plated concrete blocks containing two different sizes of debonding. Based on the experimentally verified numerical model, parametric studies are then conducted, where a nonlinear debonding crack growth parameter is proposed. The nonlinear Rayleigh wave mixing method is proven to be practical, reliable, and sensitive for detecting debonding at bonded concrete-FRP interfaces in FRP-strengthened reinforced concrete (RC) structures.Yuqiao Cao, Ching Tai Ng, Scott T. Smit

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