3,003 research outputs found

    Determination of Trace Silicone Contamination on Composites by Quantitative XPS and LIBS

    Get PDF
    Surface treatment and surface characterization techniques are critical to ensure that adherends are chemically activated and free of contaminants prior to adhesive bonding. Silicone contamination from mold-release agents and other sources can interfere with interfacial bonding, decreasing the durability and performance of bonded composite structures. Tools and methods are needed that can be used in a production environment to reliably detect low levels of contaminants in a rapid, simple, and cost-effective manner to improve bond reliability. In this work, surface characterization of carbon fiber reinforced polymer (CFRP) composites was performed using laser induced breakdown spectroscopy (LIBS) and the results were compared with those obtained from X-ray photoelectron spectroscopy (XPS). The objective was to investigate the ability to quantify the surface species measured by LIBS since it offers many advantages over XPS in terms of ease of use, sample preparation, and real-time results. The as-processed CFRP panels had trace surface silicone contamination from the fabrication process, the source of which was not investigated. The composites were laser treated at select average laser power levels, resulting in varying levels of contamination reduction. The Si atomic percentage measurements using XPS were conducted both before and after laser ablation. The XPS results were compared with those obtained from LIBS to assess the reliability of each technique for surface contaminant characterization. The results showed an excellent correlation in Si atomic concentration between the two techniques

    Bycatch in a Commercial Lobster Fishery: Effects on Two Benthic Predators, Sea Raven and Longhorn Sculpin

    Get PDF
    Studying the species‐specific responses to fishing capture is critical for effective management and conservation of bycatch species given that acute stress incurred from capture and handling may ultimately lead to mortality. While species of low commercial value are often overlooked, having accurate information on the effects of capture on all species is necessary for ecosystem‐based management. Sea Raven (SR) Hemitripterus americanus and Longhorn Sculpin (LHS) Myoxocephalus octodecemspinosus are routinely captured in the commercial American lobster Homarus americanus fishery in the Gulf of Maine, and they are discarded due to low commercial value. Despite a lack of economic value, these predatory species play important roles in shaping the benthic communities that they inhabit, highlighting the need to study their stress and mortality due to capture and handling. To help understand the effects of the lobster fishery on these species, the current study evaluated the physical, behavioral, and physiological stress responses of SR and LHS to capture in the state of Maine Zone G commercial lobster fishery. Collectively, our results suggest that although these species appeared to be resilient to capture based on an overt injury assessment, stress responses occurred based on reflex impairment and physiological perturbations, and these responses were species‐specific. Given the prevalence of behavioral and physiological stress in this study, further research into the survival outcomes of SR and LHS following release in the commercial lobster fishery is warranted

    Biodiversity of CS-proteoglycan sulphation motifs: chemical messenger recognition modules with roles in information transfer, control of cellular behaviour and tissue morphogenesis

    Get PDF
    Chondroitin sulphate glycosaminoglycan chains on cell and ECM proteoglycans can no longer be regarded as merely hydrodynamic space fillers. Overwhelming evidence over recent years indicates that sulphation motif sequences within the chondroitin sulphate chain structure are a source of significant biological information to cells and their surrounding environment. Chondroitin sulphate sulphation motifs have been shown to interact with a wide variety of bioactive molecules e.g. cytokines, growth factors, chemokines, morphogenetic proteins, enzymes and enzyme inhibitors, as well as structural components within the extracellular milieu. They are therefore capable of modulating a panoply of signalling pathways thus controlling diverse cellular behaviours including proliferation, differentiation, migration and matrix synthesis. Consequently, through these motifs, chondroitin sulphate proteoglycans play significant roles in the maintenance of tissue homeostasis, morphogenesis, development, growth and disease. Here we review (i) the biodiversity of chondroitin sulphate proteoglycans and their sulphation motif sequences and (ii) the current understanding of the signalling roles they play in regulating cellular behaviour during tissue development, growth, disease and repai

    Formation and Evolution of Planetary Systems: Cold Outer Disks Associated with Sun-like stars

    Full text link
    We present the discovery of debris systems around three solar mass stars based upon observations performed with the Spitzer Space Telescope as part of a Legacy Science Program, ``the Formation and Evolution of Planetary Systems'' (FEPS). We also confirm the presence of debris around two other stars. All the stars exhibit infrared emission in excess of the expected photospheres in the 70 micron band, but are consistent with photospheric emission at <= 33 micron. This restricts the maximum temperature of debris in equilibrium with the stellar radiation to T < 70 K. We find that these sources are relatively old in the FEPS sample, in the age range 0.7 - 3 Gyr. Based on models of the spectral energy distributions, we suggest that these debris systems represent materials generated by collisions of planetesimal belts. We speculate on the nature of these systems through comparisons to our own Kuiper Belt, and on the likely planet(s) responsible for stirring the system and ultimately releasing dust through collisions. We further report observations of a nearby star HD 13974 (d =11 pc) that is indistinguishable from a bare photosphere at both 24 micron and 70 micron. The observations place strong upper limits on the presence of any cold dust in this nearby system (L_IR/L_* < 10^{-5.2}).Comment: 31 pages, 9 figures, accepted for publication in Ap

    Impact of the diagnostic label for a low-risk prostate lesion: protocol for two online factorial randomised experiments

    Get PDF
    INTRODUCTION: Many types of prostate cancer present minimal risk to a man's lifespan or well-being, but existing terminology makes it difficult for men to distinguish these from high-risk prostate cancers. This study aims to explore whether using an alternative label for low-risk prostate cancer influences management choice and anxiety levels among Australian men and their partners.METHODS AND ANALYSIS: We will run two separate studies for Australian men and Australian women with a male partner. Both studies are between-subjects factorial (3×2) randomised online hypothetical experiments. Following consent, eligible participants will be randomised 1:1:1 to three labels: 'low-risk prostate cancer, Gleason Group 1', 'low-risk prostate neoplasm' or 'low-risk prostate lesion'. Participants will then undergo a second randomisation step with 1:1 allocation to the provision of detailed information on the benefits and harms of different management choices versus the provision of less detailed information about management choices. The required sample sizes are 1290 men and 1410 women. The primary outcome is the participant choice of their preferred management strategy: no immediate treatment (prostate-specific antigen (PSA)-based monitoring or active surveillance using PSA, MRI, biopsy with delayed treatment for disease progression) versus immediate treatment (prostatectomy or radiation therapy). Secondary outcomes include preferred management choice (from the four options listed above), diagnosis anxiety, management choice anxiety and management choice at a later time point (for participants who initially choose a monitoring strategy).ETHICS AND DISSEMINATION: Ethics approval has been received from The University of Sydney Human Research Ethics Committee (2023/572). The results of the study will be published in a peer-reviewed medical journal and a plain language summary of the findings will be shared on the Wiser Healthcare publications page http://www.wiserhealthcare.org.au/category/publications/ TRIAL REGISTRATION NUMBERS: Australian New Zealand Clinical Trials Registry (ID 386701 and 386889).</p

    Methane, Manganese, and Helium in Hydrothermal Plumes following Volcanic Eruptions on the East Pacific Rise near 9°500N

    Get PDF
    As part of a rapid response cruise in May 2006, we surveyed water column hydrothermal plumes and bottom conditions on the East Pacific Rise between 9°46.0\u27N and 9°57.6\u27N, where recent seafloor volcanic activity was suspected. Real-time measurements included temperature, light transmission, and salinity. Samples of the plume waters were analyzed for methane, manganese, helium concentrations, and the δ13C of methane. These data allow us to examine the effects of the 2005–2006 volcanic eruption(s) on plume chemistry. Methane and manganese are sensitive tracers of hydrothermal plumes, and both were present in high concentrations. Methane reached 347 nM in upper plume samples (250 m above seafloor) and exceeded 1085 nM in a near-bottom sample. Mn reached 54 nM in the upper plume and 98 nM in near-bottom samples. The concentrations of methane and Mn were higher than measurements made after a volcanic eruption in the same area in 1991, but the ratio of CH4/Mn, at 6.7, is slightly lower, though still well above the ratios measured in chronic plumes. High concentrations of methane in near-bottom samples were associated with areas of microbial mats and diffuse venting documented in seafloor imagery. The isotopic composition of the methane carbon shows evidence of active microbial oxidation; however, neither the fractionation factor nor the source of the eruption-associated methane can be determined with any certainty. Considerable scatter in the isotopic data is due to diverse sources for the methane as well as fractionation as methane is consumed. One sample at +21% versus Peedee belemnite standard is among the most enriched methane carbon values reported in a hydrothermal plume to date

    Childhood Predictors of Adult Functional Outcomes in the Multimodal Treatment Study of Attention-Deficit/Hyperactivity Disorder (MTA)

    Get PDF
    ObjectiveRecent results from the Multimodal Treatment Study of Attention-Deficit/Hyperactivity Disorder (ADHD; MTA) have demonstrated impairments in several functioning domains in adults with childhood ADHD. The childhood predictors of these adult functional outcomes are not adequately understood. The objective of the present study was to determine the effects of childhood demographic, clinical, and family factors on adult functional outcomes in individuals with and without childhood ADHD from the MTA cohort.MethodRegressions were used to determine associations of childhood factors (age range 7-10 years) of family income, IQ, comorbidity (internalizing, externalizing, and total number of non-ADHD diagnoses), parenting styles, parental education, number of household members, parental marital problems, parent-child relationships, and ADHD symptom severity with adult outcomes (mean age 25 years) of occupational functioning, educational attainment, emotional functioning, sexual behavior, and justice involvement in participants with (n&nbsp;= 579) and without (n&nbsp;= 258) ADHD.ResultsPredictors of adult functional outcomes in ADHD included clinical factors such as baseline ADHD severity, IQ, and comorbidity; demographic factors such as family income, number of household members and parental education; and family factors such as parental monitoring and parental marital problems. Predictors of adult outcomes were generally comparable for children with and without ADHD.ConclusionChildhood ADHD symptoms, IQ, and household income levels are important predictors of adult functional outcomes. Management of these areas early on, through timely treatments for ADHD symptoms, and providing additional support to children with lower IQ and from households with low incomes, could assist in improving adult functioning
    • …
    corecore