1,750 research outputs found

    Measurement of residual stress by using focused ion beam and digital image correlation method in thin-sized wires used for steel cords

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    Residual stress in the axial direction of the steel wires has been measured by using a method based on the combination of the focused ion beam (FIB) milling and digital image correlation software. That is, the residual stress was calculated from the measured displacement field before and after the introduction of a slot along the steel wires. The displacement was obtained by the digital correlation analysis of high-resolution scanning electron micrographs, while the slot was introduced by FIB milling with low energy beam. The fitting of the experimental results to an analytical model with the independent Young's modulus determined allows us to find the residual stress. The complete experimental procedures are described and its feasibilities are also evaluated for the thin-sized steel wires.open112sciescopu

    A Review of Vacuum Degradation Research and the Experimental Outgassing Research of the Core Material- Pu foam on Vacuum Insulation Panels

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    AbstractVacuum Insulation Panels(VIPs) have been regarded as a super thermal insulation material with a thermal resistance of about 5-8 times higher than that of equally thick conventional polyurethane boards. In this paper, the researches on factors influencing interior pressure in VIPs, including gas and water vapor permeation through the barrier and outgassing of the core materials, were reviewed respectively. Following this, aiming at the outgassing from open cell PU foam, the specific outgassing rate of the core material is tested not only at room temperature but also at low and high temperatures by an orifice known-conductance method

    Optimal Portfolio Allocation under a Probabilistic Risk Constraint and the Incentives for Financial Innovation

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    We derive, in a complete markets environment, an investor's optimal portfolio allocation subject to both a budget constraint and a probabilistic risk constraint. We demonstrate that the set of feasible portfolios need not be connected or convex, while the number of local optima increases exponentially with the number of securities implying that finding the optimal portfolio is computationally complex (NP hard). The resulting optimal portfolio allocation may not be monotonic in the state-price density. A novel type of financial innovation, which splits states of nature, is shown to weakly enhance welfare, restore monotonicity in the state-price density, and may reduce complexity

    Conjugated linoleic acid production and probiotic assessment of Lactobacillus plantarum isolated from Pico cheese

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    peer-reviewedLactic acid bacteria isolated from a traditional Azorean cheese were screened for their ability to convert free linoleic acid to conjugated linoleic acid (CLA). Two strains of Lactobacillus plantarum were recognized as potential CLA producers. GC analysis identified cis-9, trans-11 C18:2 as the predominant isomer (10–14 μg/mL), followed by trans-9, trans-11 C18:2 (4–6 μg/mL). The CLA producing strains demonstrated strong biofilm capacity, high cell surface hydrophobicity and good auto-aggregation ability. These strains were capable of surviving in the presence of bile salts (0.3%) and pancreatin (0.1%), but only the highest CLA producer (L3C1E8) was able to resist low pH (2.5). Moreover, the CLA-producers showed good adhesion capacity to intestinal human cells (Caco-2 and HT-29) and were able to prevent colonization of Escherichia coli. Of the two strains, Lactobacillus plantarum L3C1E8 revealed superior probiotic properties and great potential for producing food products enriched in the two CLA isomers, cis-9, trans-11 C18:2 (60%) and trans-9, trans-11 C18:2 (25%)

    Facile post modification synthesis of copper-doped mesoporous bioactive glass with high antibacterial performance to fight bone infection

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    Successful treatment of infected bone defects caused by multi-drug resistant bacteria (MDR) has become a major clinical challenge, stressing the urgent need for effective antibacterial bone graft substitutes. Mesoporous bioactive glass nanoparticles (MBGNs), a rapidly emerging class of nanoscale biomaterials, offer specific advantages for the development of biomaterials to treat bone infection due to endowed antibacterial features. Herein, we propose a facile post-modification sol-gel strategy to synthesize effective antibacterial MBGNs doped with copper ions (Cu-PMMBGNs). In this strategy, amine functional groups as chelating agents were introduced to premade mesoporous silica nanoparticles (MSNs) which further facilitate the incorporation of high content of calcium (∼17 mol%) and copper ions (∼8 mol%) without compromising nanoparticle shape, mesoporosity, and homogeneity. The resulting nanoparticles were degradable and showed rapidly induce abundant deposition of apatite crystals on their surface upon soaking in simulated body fluids (SBF) after 3 days. Cu-PMMBGNs exhibited a dose-dependent inhibitory effect on Methicillin-resistant Staphylococcus aureus (MRSA) bacteria, which are common pathogens causing severe bone infections. Most importantly, the nanoparticles containing 5 mol% copper ions at concentrations of 500 and 1000 μg.mL−1 showed highly effective antibacterial performance as reflected by a 99.9 % reduction of bacterial viability. Nanoparticles at a concentration of 500 μg.mL−1 showed no significant cytotoxicity toward preosteoblast cells (∼85–89 % cell viability) compared to the control group. In addition, the nanoscale properties of synthesized Cu-PMMBGNs (∼100 nm in size) facilitated their internalization into preosteoblast cells, which highlights their potential as intracellular carriers in combating intracellular bacteria. Therefore, these copper-doped nanoparticles hold strong promise for use as an antibacterial component in antibacterial bone substitutes such as hydrogels, nanocomposites, and coatings.</p

    A dedicated haem lyase is required for the maturation of a novel bacterial cytochrome c with unconventional covalent haem binding

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    In bacterial c-type cytochromes, the haem cofactor is covalently attached via two cysteine residues organized in a haem c-binding motif. Here, a novel octa-haem c protein, MccA, is described that contains only seven conventional haem c-binding motifs (CXXCH), in addition to several single cysteine residues and a conserved CH signature. Mass spectrometric analysis of purified MccA from Wolinella succinogenes suggests that two of the single cysteine residues are actually part of an unprecedented CX15CH sequence involved in haem c binding. Spectroscopic characterization of MccA identified an unusual high-potential haem c with a red-shifted absorption maximum, not unlike that of certain eukaryotic cytochromes c that exceptionally bind haem via only one thioether bridge. A haem lyase gene was found to be specifically required for the maturation of MccA in W. succinogenes. Equivalent haem lyase-encoding genes belonging to either the bacterial cytochrome c biogenesis system I or II are present in the vicinity of every known mccA gene suggesting a dedicated cytochrome c maturation pathway. The results necessitate reconsideration of computer-based prediction of putative haem c-binding motifs in bacterial proteomes

    Finite reduction and Morse index estimates for mechanical systems

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    A simple version of exact finite dimensional reduction for the variational setting of mechanical systems is presented. It is worked out by means of a thorough global version of the implicit function theorem for monotone operators. Moreover, the Hessian of the reduced function preserves all the relevant information of the original one, by Schur's complement, which spontaneously appears in this context. Finally, the results are straightforwardly extended to the case of a Dirichlet problem on a bounded domain.Comment: 13 pages; v2: minor changes, to appear in Nonlinear Differential Equations and Application

    A modeling approach shows the effects of different light-dark schemes on the entrainment ability of the suprachiasmatic nucleus

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    In mammals, an endogenous clock located in the suprachiasmatic nucleus (SCN), synchronizes physiological and biological rhythms to the environmental light–dark cycle. In experiments, most researchers applied rectangular scheme as the external light–dark scheme received by the SCN neuronal oscillators. However, the external light intensity changes gradually throughout the day. Therefore, trapezoidal schemes (twilight) or sinusoidal schemes were also applied. Thus far, the effects of different light–dark schemes on the oscillators of the SCN did not get fully explored. In the present study, we theoretically analyzed how the five common light–dark schemes affect the entrainment ability of the SCN, based on a Poincaré model. We numerically found that when the maximum light intensity, the minimum light intensity, and the total amount of light exposure per cycle were the same, the largest entrainment range was obtained in the oscillators receiving more light in the daytime. However if, under the condition of 12:12-h illumination, the total amount of light exposure per cycle was the same, the maximum light intensity during the day leaded to an increased range of entrainment. Moreover, the entrainment range was reduced when the photoperiod was extended. Note that, increasing the maximum light intensity increased the entrainment ability of all light–dark schemes. Our results exposes the important role of light–dark schemes in the entrainment ability of the SCN network, and provides a potential explanation for the diversity of the entrainment range between diurnal and nocturnal animals. Circadian clocks in health and diseas
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