2,008 research outputs found

    Towards Understanding Photodegradation Pathways in Lignins:The Role of Intramolecular Hydrogen Bonding in Excited States

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    The photoinduced dynamics of the lignin building blocks syringol, guaiacol, and phenol were studied using time-resolved ion yield spectroscopy and velocity map ion imaging. Following irradiation of syringol and guaiacol with a broad-band femtosecond ultraviolet laser pulse, a coherent superposition of out-of-plane OH torsion and/or OMe torsion/flapping motions is created in the first excited 1ππ* (S1) state, resulting in a vibrational wavepacket, which is probed by virtue of a dramatic nonplanar → planar geometry change upon photoionization from S1 to the ground state of the cation (D0). Any similar quantum beat pattern is absent in phenol. In syringol, the nonplanar geometry in S1 is pronounced enough to reduce the degree of intramolecular H bonding (between OH and OMe groups), enabling H atom elimination from the OH group. For guaiacol, H bonding is preserved after excitation, despite the nonplanar geometry in S1, and prevents O–H bond fission. This behavior affects the propensities for forming undesired phenoxyl radical sites in these three lignin chromophores and provides important insight into their relative “photostabilities” within the larger biopolymer

    History of the Innovation of Damage Control for Management of Trauma Patients: 1902-2016

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    Objective: To review the history of the innovation of damage control (DC) for management of trauma patients. Background: DC is an important development in trauma care that provides a valuable case study in surgical innovation. Methods: We searched bibliographic databases (1950-2015), conference abstracts (2009-2013), Web sites, textbooks, and bibliographies for articles relating to trauma DC. The innovation of DC was then classified according to the Innovation, Development, Exploration, Assessment, and Long-term study model of surgical innovation. Results: The innovation\u27\u27 of DC originated from the use of therapeutic liver packing, a practice that had previously been abandoned after World War II because of adverse events. It then developed\u27\u27 into abbreviated laparotomy using rapid conservative operative techniques.\u27\u27 Subsequent exploration\u27\u27 resulted in the application of DC to increasingly complex abdominal injuries and thoracic, peripheral vascular, and orthopedic injuries. Increasing use of DC laparotomy was followed by growing reports of postinjury abdominal compartment syndrome and prophylactic use of the open abdomen to prevent intra-abdominal hypertension after DC laparotomy. By the year 2000, DC surgery had been widely adopted and was recommended for use in surgical journals, textbooks, and teaching courses ( assessment\u27\u27 stage of innovation). Long-term study\u27\u27 of DC is raising questions about whether the procedure should be used more selectively in the context of improving resuscitation practices. Conclusions: The history of the innovation of DC illustrates how a previously abandoned surgical technique was adapted and readopted in response to an increased understanding of trauma patient physiology and changing injury patterns and trauma resuscitation practices

    A Pseudo-Two-Dimensional (P2D) Model for FeS2 Conversion Cathode Batteries

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    Conversion cathode materials are gaining interest for secondary batteries due to their high theoretical energy and power density. However, practical application as a secondary battery material is currently limited by practical issues such as poor cyclability. To better understand these materials, we have developed a pseudo-two-dimensional model for conversion cathodes. We apply this model to FeS2 - a material that undergoes intercalation followed by conversion during discharge. The model is derived from the half-cell Doyle-Fuller-Newman model with additional loss terms added to reflect the converted shell resistance as the reaction progresses. We also account for polydisperse active material particles by incorporating a variable active surface area and effective particle radius. Using the model, we show that the leading loss mechanisms for FeS2 are associated with solid-state diffusion and electrical transport limitations through the converted shell material. The polydisperse simulations are also compared to a monodisperse system, and we show that polydispersity has very little effect on the intercalation behavior yet leads to capacity loss during the conversion reaction. We provide the code as an open-source Python Battery Mathematical Modelling (PyBaMM) model that can be used to identify performance limitations for other conversion cathode materials

    Characterization of optical properties of ZnO nanoparticles for quantitative imaging of transdermal transport

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    Widespread applications of ZnO nanoparticles (NP) in sun-blocking cosmetic products have raised safety concerns related to their potential transdermal penetration and resultant cytotoxicity. Nonlinear optical microscopy provides means for high-contrast imaging of ZnO NPs lending in vitro and in vivo assessment of the nanoparticle uptake in skin, provided their nonlinear optical properties are characterized. We report on this characterization using ZnO NP commercial product, Zinclear, mean-sized 21 nm. Two-photon action cross-section of this bandgap material (Ebg = 3.37 eV, λbg = 370 nm) measured by two techniques yielded consistent results of ηZnOσZnO(2ph) = 6.2 ± 0.8 ÎŒGM at 795 nm, and 32 ± 6 ÎŒGM at 770 nm per unit ZnO crystal cell, with the quantum efficiency of ηZnO = (0.9 ± 0.2) %. In order to demonstrate the quantitative imaging, nonlinear optical microscopy images of the excised human skin topically treated with Zinclear were acquired and processed using σZnO(2ph) and ηZnOvalues yielding nanoparticle concentration map in skin. Accumulations of Zinclear ZnO nanoparticles were detected only on the skin surface and in skin folds reaching concentrations of 800 NPs per ÎŒm3

    Efficacy and Tolerability of Travoprost 0.004 %

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    Objective. To evaluate the efficacy and tolerability of travoprost 0.004%/timolol 0.5% fixed-dose combination (TTFC) in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT) inadequately controlled on beta-blocker monotherapy. Methods. In this phase IV, open-label study, 156 patients on beta-blocker monotherapy with mean intraocular pressure (IOP) between 18 and 32 mmHg were randomized (no washout period) to receive TTFC for 8 weeks (TTFC group) or to continue beta-blocker monotherapy for 4 weeks followed by TTFC for the remaining 4 weeks (beta-blocker group). Results. The mean IOP (±standard deviation) at baseline in the TTFC and beta-blocker groups was 22.5±2.5 mmHg and 22.2±2.3 mmHg, respectively, and at weeks 4 and 8, was 16.7±3.1 mmHg and 16.1±3.1 mmHg, respectively, in TTFC group and 21.1±3.1 mmHg and 16.1±2.8 mmHg, respectively, in the beta-blocker group. There was a significant least squares mean difference between TTFC and beta-blocker in 8 a.m. IOP at week 4 (−4.6 mmHg; one-sided 95% confidence interval [−inf, −3.9]; p<0.0001 [primary endpoint]); the upper bound of the 95% confidence interval was within the prespecified limit (<0). Both treatments were well tolerated. Conclusion. Superior IOP control was achieved with TTFC in patients with OAG or OHT previously uncontrolled with beta-blockers. No new safety findings were identified. This trial is registered with ClinicalTrials.gov NCT02003391

    Clinical Study Efficacy and Tolerability of Travoprost 0.004%/Timolol 0.5% Fixed-Dose Combination for the Treatment of Primary Open-Angle Glaucoma or Ocular Hypertension Inadequately Controlled with Beta-Blocker Monotherapy

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    Objective. To evaluate the efficacy and tolerability of travoprost 0.004%/timolol 0.5% fixed-dose combination (TTFC) in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT) inadequately controlled on beta-blocker monotherapy. Methods. In this phase IV, open-label study, 156 patients on beta-blocker monotherapy with mean intraocular pressure (IOP) between 18 and 32 mmHg were randomized (no washout period) to receive TTFC for 8 weeks (TTFC group) or to continue beta-blocker monotherapy for 4 weeks followed by TTFC for the remaining 4 weeks (beta-blocker group). Results. The mean IOP (±standard deviation) at baseline in the TTFC and beta-blocker groups was 22.5 ± 2.5 mmHg and 22.2 ± 2.3 mmHg, respectively, and at weeks 4 and 8, was 16.7 ± 3.1 mmHg and 16.1 ± 3.1 mmHg, respectively, in TTFC group and 21.1 ± 3.1 mmHg and 16.1 ± 2.8 mmHg, respectively, in the beta-blocker group. There was a significant least squares mean difference between TTFC and beta-blocker in 8 a.m. IOP at week 4 (−4.6 mmHg; one-sided 95% confidence interval [−inf, −3.9]; &lt; 0.0001 [primary endpoint]); the upper bound of the 95% confidence interval was within the prespecified limit (&lt;0). Both treatments were well tolerated. Conclusion. Superior IOP control was achieved with TTFC in patients with OAG or OHT previously uncontrolled with beta-blockers. No new safety findings were identified. This trial is registered with ClinicalTrials.gov NCT02003391

    Unacylated-Ghrelin Impairs Hippocampal Neurogenesis and Memory in Mice and Is Altered in Parkinson’s Dementia in Humans

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    Blood-borne factors regulate adult hippocampal neurogenesis and cognition in mammals. We report that elevating circulating unacylated-ghrelin (UAG), using both pharmacological and genetic methods, reduced hippocampal neurogenesis and plasticity in mice. Spatial memory impairments observed in ghrelin-O-acyl transferase-null (GOAT/) mice that lack acyl-ghrelin (AG) but have high levels of UAG were rescued by acyl-ghrelin. Acyl-ghrelin-mediated neurogenesis in vitro was dependent on non-cell-autonomous BDNF signaling that was inhibited by UAG. These findings suggest that post-translational acylation of ghrelin is important to neurogenesis and memory in mice. To determine relevance in humans, we analyzed circulating AG:UAG in Parkinson disease (PD) patients diagnosed with dementia (PDD), cognitively intact PD patients, and controls. Notably, plasma AG:UAG was only reduced in PDD. Hippocampal ghrelin-receptor expression remained unchanged; however, GOAT+ cell number was reduced in PDD. We identify UAG as a regulator of hippocampal-dependent plasticity and spatial memory and AG:UAG as a putative circulating diagnostic biomarker of dementia

    Filterability of staphylococcal species through membrane filters following application of stressors

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    <p>Abstract</p> <p>Background</p> <p>Passage of bacterial cells through filter pores has been reported for a number of bacterial species. In this investigation, we tested the filterability of staphylococcal cultures that were exposed to several environmental stress conditions by passing them through 0.22 and 0.45 ÎŒm sterile filters, which are industry standards.</p> <p>Findings</p> <p>Results showed repeated passage of viable staphylococcal cells through both pore sizes, although more passage was seen through the 0.45 ÎŒm pore size. Of the three staphylococcal species, <it>S. lugdunensis </it>showed the best passage at relatively higher numbers regardless of the treatment, while both <it>S. aureus </it>and <it>S. epidermidis </it>showed limited passage or complete inhibition.</p> <p>Conclusion</p> <p>The data showed that staphylococcal bacteria were capable of passing through sterile filters in a viable state. There was better passage through 0.45 ÎŒm sterile filters than through the 0.22 ÎŒm sterile filters. Application of a stress condition did not appear to enhance filterability of these bacterial cultures.</p

    Landscape Mapping of Functional Proteins in Insulin Signal Transduction and Insulin Resistance: A Network-Based Protein-Protein Interaction Analysis

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    The type 2 diabetes has increased rapidly in recent years throughout the world. The insulin signal transduction mechanism gets disrupted sometimes and it's known as insulin-resistance. It is one of the primary causes associated with type-2 diabetes. The signaling mechanisms involved several proteins that include 7 major functional proteins such as INS, INSR, IRS1, IRS2, PIK3CA, Akt2, and GLUT4. Using these 7 principal proteins, multiple sequences alignment has been created. The scores between sequences also have been developed. We have constructed a phylogenetic tree and modified it with node and distance. Besides, we have generated sequence logos and ultimately developed the protein-protein interaction network. The small insulin signal transduction protein arrangement shows complex network between the functional proteins
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