Poly[aqua­[μ3-4-carb­oxy-2-(pyridin-4-yl)-1H-imidazole-5-carboxyl­ato-κ5 N 1,O 5:N 3,O 4:N 2]nickel(II)]

The water-coordinated Ni2+ cation in the title compound, [Ni(C10H5N3O4)(H2O)]n, assumes an octa­hedral NiN3O3 coord­ination mode and is N,O-chelated by two deprotonated 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarb­oxy­lic acid (HPyImDC2−) ligands, forming a layer structure extending in the bc plane. The chains are arranged along the b-axis direction, forming a layer structure extending in the bc plane. O—H⋯O hydrogen bonding between the layers results in the formation of a three-dimensional supra­molecular framework. The structure is isotypic with the Zn analogue [Li et al. (2009). Cryst. Growth Des. 6, 3423–3431]

Test methods for measuring pure mode III delamination toughness of composite

This paper focuses on the characterization of pure mode III delamination behavior of composite mate- rials. The development for pure mode III delamination testing methods is reviewed. Two testing methods for mode III experiments were evaluated: a novel test proposed in our previous study, termed Edge Ring Crack Torsion (ERCT) test, and the widely used Edge Crack Torsion (ECT) test. The two methods were compared by experiment and finite element analysis. The results demonstrate the advantage of ERCT. The limitations of the ECT test are discussed

Parametric and economic analysis of high-temperature cascade organic Rankine cycle with a biphenyl and diphenyl oxide mixture

High-temperature organic Rankine cycle (ORC) systems have the potential to improve the heat-to-power conversion efficiency and expand the temperature range for heat recovery, heat battery and solar power generation. Restricted by the critical temperature of the commonly used organic working fluids, the current ORC technology has a maximum working temperature of around 300 °C. This paper proposes a high-temperature cascade organic Rankine cycle (CORC) system using a biphenyl and diphenyl oxide (BDO) mixture as the top cycle fluid and conventional organic fluids for the bottom cycle. The BDO mixture has excellent heat stability over a wide operation condition from 12 °C to 400 °C in single-phase and binary-phase states. However, at present a detailed study on the ORC using the mixture is lacking. In this paper, a parametric analysis of the high-temperature CORC system is conducted. A mathematical model based on the equivalent hot side temperature is built to simulate the ORC efficiency. The thermodynamic and exergetic performances of the novel CORC system under different bottom ORC working fluids, mixing chamber temperatures, evaporation temperatures, and condensation temperatures are investigated. The results show the maximum thermal efficiency of the CORC system is 38.74 % and 40.26 % at top ORC evaporation temperatures of 360 °C and 400 °C. The largest exergy destruction takes place in the heat exchanger between the top and bottom ORCs. Besides, the heat regenerators have a significant impact on the thermodynamic performance and can elevate the CORC efficiency by about 4 %. The proposed system has a higher efficiency and a lower equipment cost than conventional steam Rankine cycle at 400 °C while eliminating the challenges of wet steam turbines

Chaos-assisted two-octave-spanning microcombs

Since its invention, optical frequency comb has revolutionized a broad range of subjects from metrology to spectroscopy. The recent development of microresonator-based frequency combs (microcombs) provides a unique pathway to create frequency comb systems on a chip. Indeed, microcomb-based spectroscopy, ranging, optical synthesizer, telecommunications and astronomical calibrations have been reported recently. Critical to many of the integrated comb systems is the broad coverage of comb spectra. Here, microcombs of more than two-octave span (450 nm to 2,008 nm) is demonstrated through χ^((2)) and χ^((3)) nonlinearities in a deformed silica microcavity. The deformation lifts the circular symmetry and creates chaotic tunneling channels that enable broadband collection of intracavity emission with a single waveguide. Our demonstration introduces a new degree of freedom, cavity deformation, to the microcomb studies, and our microcomb spectral range is useful for applications in optical clock, astronomical calibration and biological imaging

Modélisation numérique d'assemblages collés (application à la réparation de structures en composites)

Cette étude fait partie d'un programme de recherche concernant la réparation de structures composites par collage de patchs externes. Les objectifs principaux de ce programme sont d'une part l'identification de l'ensemble des facteurs susceptibles d influencer les performances à long terme de ce type de réparation, et d autre part de déterminer dans quelle mesure l utilisation de tels assemblages peuvent s'avérer une solution optimale. La conception d'un tel système passe obligatoirement par le développement d'un outil de simulation et de prédiction robuste du fait des divers mécanismes d endommagement pouvant intervenir de fa?on très complexe et de la rupture finale du système résultant d une propagation des zones endommagées. Cette étude compose d une et d autre l aspect de la modélisation numérique, et l'aspect expérimental. Le dialogue entre les résultats numériques et expérimentaux permet, d une part de comprendre les mécanismes d endommagement et l évolution de ce dernier dans le système réparé, d autre part de valider le modèle numérique. En particulier, nos efforts ont été concentrés, en utilisant le logiciel LS-dyna, sur l application des modèles de zone cohésive (MZC). Le comportement au délaminage d un composite carbone/époxyde et de l adhésif sont étudié avec les essais en mode I, mode II et mode mixte. Une étude paramétrique de MZC est effectuée. Le modèle de zone cohésive validé est utilisé pour modéliser le comportement en traction des composites réparés par collage de patches externesThis study is one part of a program of research with regard to the repair of composite structure with extern bonded-patches. The principal objectives of this program are, on one side, the identification of all the factors susceptible to influence the long-term performance of this type of repair, on the other, to determine the extent to which the use of such assemblage can be proved to be an optimal solution. The conception of such a system needs essentially the development of a tool of simulation and of robust prediction because various mechanisms of damage can take place in a very complex way and the final fracture of the system arise from the propagation of damage zones. This study consists of both numerical simulation and experimental aspect which can help us, on one side, understand the mechanisms of damage and its evolution in a repair structure, on the other, valid the numerical model. In particular, we concentrate in the application of cohesive zone model using LS-dyna. The behavior of delamination of carbon/epoxy composite and the adhesive is studied with the experiments in mode I, mode II and mode mixed. A parametric study is carried out. The validated cohesive zone model is used to simulate the tensile behavior of composite repaired by extern bonded-patchesDIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Human Mitochondrial tRNA Mutations in Maternally Inherited Deafness

AbstractMutations in mitochondrial tRNA genes have been shown to be associated with maternally inherited syndromic and non-syndromic deafness. Among those, mutations such as tRNALeu(UUR)3243A>G associated with syndromic deafness are often present in heteroplasmy, and the non-syndromic deafness-associated tRNA mutations including tRNASer(UCN)7445A>G are often in homoplasmy or in high levels of heteroplasmy. These tRNA mutations are the primary factors underlying the development of hearing loss. However, other tRNA mutations such as tRNAThr15927G>A and tRNASer(UCN)7444G>A are insufficient to produce a deafness phenotype, but always act in synergy with the primary mitochondrial DNA mutations, and can modulate their phenotypic manifestation. These tRNA mutations may alter the structure and function of the corresponding mitochondrial tRNAs and cause failures in tRNAs metabolism. Thereby, the impairment of mitochondrial protein synthesis and subsequent defects in respiration caused by these tRNA mutations, results in mitochondrial dysfunctions and eventually leads to the development of hearing loss. Here, we summarized the deafness-associated mitochondrial tRNA mutations and discussed the pathophysiology of these mitochondrial tRNA mutations, and we hope these data will provide a foundation for the early diagnosis, management, and treatment of maternally inherited deafness

Benzoxazolinones: Novel Bioactive Phytochemicals in Wheat with Potential Hypoglycemic Activity

Benzoxazolinones (BXs) are a group of natural compounds with biological activity. In recent years, benzoxazolinones have been identified in cereal grains and bakery foods. The most common BXs are 6-methoxy-benzoxazolin-2-one (MBOA) and 2-benzoxazolin-2-one (BOA). In this study, the contents of MBOA and BOA in 13varieties of wheat harvested in Henan Province were analyzed by LC-MS technology. Meanwhile, the inhibitory effects of MBOA and BOA on α-glucosidase and α-amylase were evaluated. The results showed that the contents of MBOA and BOA in wheat varied from 4.30 to 5.02 ng/g and 1.62 to 7.98 ng/g respectively. Interestingly, the contents of MBOA and BOA in whole wheat flour increased significantly after hot drying and germination by 1.5~2.0 and 500~1 000 times, respectively. In the aspect of hypoglycemic activity, MBOA and BOA showed reversible competitive inhibition on α-glucosidase and α-amylase. The IC50 of MBOA and BOA to α-glucosidase were 13.73 and 73.9 mg/mL, the IC50 to α-amylase were 64.98 and 17.68 mg/mL. These results revealed that BXs have the potential contribution to the hypoglycemic activity associated with whole wheat consumption. Food processing technologies such as germination can be used to enhance the concentration of BXs in the cereal food products that allow the intake of higher amounts of BXs. This study provides a new theoretical basis for the research on the health effects of whole wheat and its processed products

Kerr-Sen Black Hole as Accelerator for Spinning Particles

It has been proved that arbitrarily high-energy collision between two particles can occur near the horizon of an extremal Kerr black hole as long as the energy $E$ and angular momentum $L$ of one particle satisfies a critical relation, which is called the BSW mechanism. Previous researchers mainly concentrate on geodesic motion of particles. In this paper, we will take spinning particle which won't move along a timelike geodesic into our consideration, hence, another parameter $s$ describing the particle's spin angular momentum was introduced. By employing the Mathisson-Papapetrou-Dixon equation describing the movement of spinning particle, we will explore whether a Kerr-Sen black hole which is slightly different from Kerr black hole can be used to accelerate a spinning particle to arbitrarily high energy. We found that when one of the two colliding particles satisfies a critical relation between the energy $E$ and the total angular momentum $J$, or has a critical spinning angular momentum $s_c$, a divergence of the center-of-mass energy $E_{cm}$ will be obtained.Comment: Latex,17 pages,1 figure,minor revision,accepted by PR