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101.
Most solar UV measurements are relative to the horizontal plane. However, problems arise when one uses those UV measurements to perform risk or benefit assessments because they do not yield the actual doses people get while they are outdoors. To better estimate the UV doses people actually get while outdoors, scientists need geometric conversion factors (GCF) that change horizontal plane irradiances to average irradiances on the human body. Here we describe a simple geometric method that changes unweighted, erythemally weighted and previtamin D3-weighted UV irradiances on the horizontal plane to full cylinder and semicylinder irradiances. Scientists can use the full cylinder model to represent the complete human body, while they can use the semicylinder model to represent the face, shoulders, tops of hands and feet. We present daily, monthly and seasonally calculated averages of the GCF for these cylinder models every 5° from 20 to 70°N so that scientists can now get realistic UV doses for people who are outdoors doing a variety of different activities. The GCF show that people actually get less than half their annual erythemally weighted, and consequently half their previtamin D3-weighted, UV doses relative to the horizontal plane. Thus, scientists can now perform realistic UV risk and benefit assessments. 相似文献
102.
Dianne Pham Upamanyu Basu Ivanna Pohorilets Claudette M. St Croix Simon C. Watkins Kazunori Koide 《Angewandte Chemie (International ed. in English)》2020,59(40):17435-17441
Hydrogen peroxide (H2O2) mediates the biology of wound healing, apoptosis, inflammation, etc. H2O2 has been fluorometrically imaged with protein‐ or small‐molecule‐based probes. However, only protein‐based probes have afforded temporal insights within seconds. Small‐molecule‐based electrophilic probes for H2O2 require many minutes for a sufficient response in biological systems. Here, we report a fluorogenic probe that selectively undergoes a [2,3]‐sigmatropic rearrangement (seleno‐Mislow‐Evans rearrangement) with H2O2, followed by acetal hydrolysis, to produce a green fluorescent molecule in seconds. Unlike other electrophilic probes, the current probe acts as a nucleophile. The fast kinetics enabled real‐time imaging of H2O2 produced in endothelial cells in 8 seconds (much earlier than previously shown) and H2O2 in a zebrafish wound healing model. This work may provide a platform for endogenous H2O2 detection in real time with chemical probes. 相似文献
103.
Bacterial cellulose has the potential to be used as a biodegradable, reinforcing component in composites due to its high strength and crystallinity. However it is often problematic to use in this context as it is difficult to separate its extensively bonded fibril network. This means it can be difficult for it to be incorporated as a fine dispersion into a composite and for the true benefits of the nanofibres to be realised in terms of physical property improvement in a conventional polymer format such as injection moulding. The method of sonication (using a range of experimental conditions) was utilised to harvest fibrils from the interwoven mesh of the cellulose pellicle, and then disperse them in different solvents to allow blending and subsequent casting. The novel step identified in this process was the sonication harvesting of the nanofibres undertaken on the highly hydrated as-received pellicle fresh from the reaction media (not the dried pellicle which could not be easily separated in the selected solvent). This unique step of harvesting directly from the fresh pellicle together with conventional sonication for dispersion in chloroform produced a bacterial cellulose/poly-3-hydroxybutyrate nanocomposite which showed excellent nanofibre dispersion and significant improvement in mechanical properties. 相似文献
104.
Joyce Breger Larissa Baeva Anant Agrawal Eli Shindell Dianne E. Godar 《Photochemistry and photobiology》2013,89(3):665-670
People can get oral cancers from UV (290–400 nm) exposures. Besides high outdoor UV exposures, high indoor UV exposures to oral tissues can occur when consumers use UV‐emitting tanning devices to either tan or whiten their teeth. We compared the carcinogenic risks of skin to oral tissue cells after UVB (290–320 nm) exposures using commercially available 3D‐engineered models for human skin (EpiDerm?), gingival (EpiGing?) and oral (EpiOral?) tissues. To compare the relative carcinogenic risks, we investigated the release of cytokines, initial DNA damage in the form of cyclobutane pyrimidine dimers (CPDs), repair of CPDs and apoptotic cell numbers. We measured cytokine release using cytometric beads with flow cytometry and previously developed a fluorescent immunohistochemical assay to quantify simultaneously CPD repair rates and apoptotic cell numbers. We found that interleukin‐8 (IL‐8) release and the initial CPDs are significantly higher, whereas the CPD repair rates and apoptotic cell numbers are significantly lower for oral compared with skin tissue cells. Thus, the increased release of the inflammatory cytokine IL‐8 along with inefficient CPD repair and decreased death rates for oral compared with skin tissue cells suggests that mutations are accumulating in the surviving population of oral cells increasing people's risks for getting oral cancers. 相似文献
105.
In this work an experimental procedure was established to assess the main engineering parameters characterizing the ultrafiltration (UF) recovery of a commercial sample of sodium alginate from model solutions, using both a laboratory-scale and a pilot-scale plant equipped with ceramic tubular UF membrane modules. 相似文献
106.
Adam Loy Heike Hofmann Dianne Cook 《Journal of computational and graphical statistics》2017,26(3):478-492
The complexity of linear mixed-effects (LME) models means that traditional diagnostics are rendered less effective. This is due to a breakdown of asymptotic results, boundary issues, and visible patterns in residual plots that are introduced by the model fitting process. Some of these issues are well known and adjustments have been proposed. Working with LME models typically requires that the analyst keeps track of all the special circumstances that may arise. In this article, we illustrate a simpler but generally applicable approach to diagnosing LME models. We explain how to use new visual inference methods for these purposes. The approach provides a unified framework for diagnosing LME fits and for model selection. We illustrate the use of this approach on several commonly available datasets. A large-scale Amazon Turk study was used to validate the methods. R code is provided for the analyses. Supplementary materials for this article are available online. 相似文献
107.
In this paper we apply matrix splitting techniques and a conjugate gradient algorithm to the problem of minimizing a convex quadratic form subject to upper and lower bounds on the variables. This method exploits sparsity structure in the matrix of the quadratic form. Choices of the splitting operator are discussed, and convergence results are established. We present the results of numerical experiments showing the effectiveness of the algorithm on free boundary problems for elliptic partial differential equations, and we give comparisons with other algorithms. 相似文献
108.
109.
Ultraviolet erythema in human skin is mediated in part by membrane derivatives of arachidonic acid (AA). UVA (320–400nm) and UVB (290–320nm) have been shown to induce release of AA from intact mammalian cells in culture. In order to investigate the mechanism of this release we examined the effect of UVA and UVB on release of [3H] AA from membrane preparations of murine fibroblasts. C3H 10T1/2 cells were prelabelled for 24 h with [3H] AA. The membrane fractions of the cells were separated after lysis by differential centrifugation. The membranes were irradiated in suspension and the [3H] AA released from the membranes was determined by scintillation spectroscopy of supernatants3–4 h after irradiation. Both UVA and UVB induced release of AA from the membrane preparations. The response to UVB was small but significant, reaching levels approximately 150% of control release at doses of 1,200-4,000 J/m2. The response to UVA was larger; doses of 2.5-5.0 J/cm2 induced release equal to twice control (200%) levels, while doses of10–20 J/cm2 induced maximal release at levels approximately 400% of control. Time course studies with UVB and UVA showed maximal release at 4 h after irradiation. When the membrane preparations were incubated with a polyclonal anti-phospholipase A2 antibody the UV induced release of [3H] AA was completely inhibited in both UVB (1200 J/m2) and UVA (10 J/cm2) treated cells. These data suggest that activation of phospholipase A2 is responsible for the UV induced release of AA in mammalian cells and that the mechanism of this activation is due, in part at least, to direct photon-membrane interaction. 相似文献
110.