754 research outputs found

    trans-4,5-Dihydr­oxy-1,3-bis­(4-methoxy­phen­yl)imidazolidine-2-thione

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    In the title compound, C17H18N2O4S, where one of the N-4-methoxy­phenyl fragments is disordered over two sets of sites, the five-membered ring exhibits a nearly half-chair conformation and the two hydroxyl groups lie on opposite sides of the five-membered ring. In the crystal, the mol­ecules are linked into sheets parallel to (100) via O—H⋯O and O—H⋯S hydrogen bonds

    Fooling an Unbounded Adversary with a Short Key, Repeatedly: The Honey Encryption Perspective

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    This article is motivated by the classical results from Shannon that put the simple and elegant one-time pad away from practice: key length has to be as large as message length and the same key could not be used more than once. In particular, we consider encryption algorithm to be defined relative to specific message distributions in order to trade for unconditional security. Such a notion named honey encryption (HE) was originally proposed for achieving best possible security for password based encryption where secrete key may have very small amount of entropy. Exploring message distributions as in HE indeed helps circumvent the classical restrictions on secret keys.We give a new and very simple honey encryption scheme satisfying the unconditional semantic security (for the targeted message distribution) in the standard model (all previous constructions are in the random oracle model, even for message recovery security only). Our new construction can be paired with an extremely simple yet "tighter" analysis, while all previous analyses (even for message recovery security only) were fairly complicated and require stronger assumptions. We also show a concrete instantiation further enables the secret key to be used for encrypting multiple messages

    Dimethyl 2,6-dimethyl-1,4-dihydro­pyridine-3,5-dicarboxyl­ate

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    In the crystal of the title compound, C11H15NO4, the mol­ecules are linked into sheets by N—H⋯O and C—H⋯O hydrogen bonds. Within the mol­ecule, the 1,4-dihydro­pyridine ring exhibits a distinctive planar conformation [r.m.s. deviation from the mean plane of 0.009 (3)Å], and the other non-H atoms are almost coplanar [r.m.s. deviation = 0.021 (3) Å] with the 1,4-dihydro­pyridine ring. The conformation of the latter is governed mainly by two intra­molecular C—H⋯O non-classical inter­actions

    Behavior of innovative T-shaped multi-partition steel-concrete composite columns under concentric and eccentric compressive loadings

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    [EN] T-shaped multi-partition steel-concrete composite column, composed of several concrete-filled rectangular steel hollow sections, is considered as an innovative composite member with the ability to accommodate neighboring wall thickness with great easiness. This paper intends to study the behavior of this innovative composite member under concentric and eccentric compressive loadings. A finite element (FE) analysis model accounting for the influences of confinement effects, geometric and material nonlinearities is developed using the program ABAQUS. The ultimate strength and load-strain responses predicted from the analysis are validated against the test results in the experiments conducted by the authors. The comparisons indicate that the FE model reasonably estimates the responses of the concentrically and eccentrically loaded T-shaped multi-partition steel-concrete composite columns. The verified model is then utilized to numerically investigate the working mechanism of the columns. The load distribution between the infilled concrete and the steel tubes and the stress distribution of the concrete during the loading process are analyzed. Moreover, parametric studies are performed to investigate the behavior of T-shaped multi-partition steel-concrete composite columns under different loadings. The studied parameters include steel to concrete area ratio, concrete compressive strength, steel yield strength and load eccentricity. Combined with the experimental results, FE analysis and parametric studies, the design recommendations for T-shaped multi-partition steel-concrete composite columns under different loadings are proposed.The research work reported in this paper were supported by National Key Research and Development Program (2016YFC0701201), and National Natural Science Foundation of China (Grant No. 51578187); their financial supports are highly appreciated.Chen, J.; Zhang, S.; Huang, Z.; Zhang, X.; Guo, L. (2018). Behavior of innovative T-shaped multi-partition steel-concrete composite columns under concentric and eccentric compressive loadings. En Proceedings of the 12th International Conference on Advances in Steel-Concrete Composite Structures. ASCCS 2018. Editorial Universitat Politècnica de València. 289-296. https://doi.org/10.4995/ASCCS2018.2018.7004OCS28929

    trans-4,5-Dihydr­oxy-1,3-diphenyl­imidazolidine-2-thione

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    In the title compound, C15H14N2O2S, the five-membered ring adopts an envelope conformation and the two hydr­oxy groups lie on opposite sides of the ring. The six-membered rings are oriented at a dihedral angle of 22.63 (3)°. In the crystal structure, inter­molecular O—H⋯S and O—H⋯O hydrogen bonds link the mol­ecules into a two-dimensional network

    Fatigue evaluation of metallic components based on chaotic characteristics of second harmonic generation signal

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    In the nonlinear ultrasonic technique, the nonlinear received signal, such as second harmonic generation (SHG) signal in higher harmonic experiments, is complicated and non-stationary time series which reflects the fatigue damage of metal components. To effectively evaluate the fatigue damage of metal components, especially the earlier fatigue damage, the chaos and fractal theory are proposed to analyze the received signal of higher harmonic experiments. Chaotic characteristics, for example Lyapunov exponent, correlation dimension and Kolmogorov entropy, are extracted to evaluate the fatigue damage. Experiments results indicate that chaotic characteristics can reasonably characterize and evaluate the fatigue state of beams, which the variation trend of chaotic characteristics has a close relationship with fatigue crack propagation. Furthermore, chaotic characteristics are very sensitive to earlier fatigue damage of used connecting rods, especially the Lyapunov exponent. Therefore, chaos and fractal theory could effectively extract the nonlinear received signals, and chaotic characteristics could reasonably evaluate the fatigue damage state of metal components

    Tissue microarray immunohistochemical detection of brachyury is not a prognostic indicator in chordoma.

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    Brachyury is a marker for notochord-derived tissues and neoplasms, such as chordoma. However, the prognostic relevance of brachyury expression in chordoma is still unknown. The improvement of tissue microarray technology has provided the opportunity to perform analyses of tumor tissues on a large scale in a uniform and consistent manner. This study was designed with the use of tissue microarray to determine the expression of brachyury. Brachyury expression in chordoma tissues from 78 chordoma patients was analyzed by immunohistochemical staining of tissue microarray. The clinicopathologic parameters, including gender, age, location of tumor and metastatic status were evaluated. Fifty-nine of 78 (75.64%) tumors showed nuclear staining for brachyury, and among them, 29 tumors (49.15%) showed 1+ (<30% positive cells) staining, 15 tumors (25.42%) had 2+ (31% to 60% positive cells) staining, and 15 tumors (25.42%) demonstrated 3+ (61% to 100% positive cells) staining. Brachyury nuclear staining was detected more frequently in sacral chordomas than in chordomas of the mobile spine. However, there was no significant relationship between brachyury expression and other clinical variables. By Kaplan-Meier analysis, brachyury expression failed to produce any significant relationship with the overall survival rate. In conclusion, brachyury expression is not a prognostic indicator in chordoma
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