3,548 research outputs found

    Seismic Analysis of Tunnel Surrounded by Soft Soil in Shanghai

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    Based on the test results, the analysis of earthquake resistance of tunnel surrounded by soft soil in Shanghai is presented in this paper. The tunnel is located in the soft soil and sand, respectively. The reaction acceleration, pore water pressure and the settlement of the tunnel under 7-degree earthquake are given and compared

    The truncated Hamburger matrix moment problems in the nondegenerate and degenerate cases, and matrix continued fractions

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    AbstractThe present paper deals simultaneously with the nondegenerate and degenerate truncated Hamburger matrix moment problems in a unified way based on the use of the Schur algorithm involving matrix continued fractions. A full analysis of them together with a relative matrix moment problem on the real axis is given. With the help of the correspondence between the moment problem on the real axis and the Nevanlinna-Pick (NP) interpolation, the solutions of the nontangential NP interpolation in the Nevanlinna class are derived as an application

    Finite element analysis of porously punched prosthetic short stem virtually designed for simulative uncemented hip arthroplasty

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    Background: There is no universal hip implant suitably fills all femoral types, whether prostheses of porous short-stem suitable for Hip Arthroplasty is to be measured scientifically. Methods: Ten specimens of femurs scanned by CT were input onto Mimics to rebuild 3D models; their *stl format dataset were imported into Geomagic-Studio for simulative osteotomy; the generated *.igs dataset were interacted by UG to fit solid models; the prosthesis were obtained by the same way from patients, and bored by punching bears designed by Pro-E virtually; cements between femora and prosthesis were extracted by deleting prosthesis; in HyperMesh, all compartments were assembled onto four artificial joint style as: (a) cemented long-stem prosthesis; (b) porous long-stem prosthesis; (c) cemented short-stem prosthesis; (d) porous short-stem prosthesis. Then, these numerical models of Finite Element Analysis were exported to AnSys for numerical solution. Results: Observed whatever from femur or prosthesis or combinational femora-prostheses, “Kruskal-Wallis” value p > 0.05 demonstrates that displacement of (d) ≈ (a) ≈ (b) ≈ (c) shows nothing different significantly by comparison with 600 N load. If stresses are tested upon prosthesis, (d) ≈ (a) ≈ (b) ≈ (c) is also displayed; if upon femora, (d) ≈ (a) ≈ (b) < (c) is suggested; if upon integral joint, (d) ≈ (a) < (b) < (c) is presented. Conclusions: Mechanically, these four sorts of artificial joint replacement are stabilized in quantity. Cemented short-stem prostheses present the biggest stress, while porous short-stem & cemented long-stem designs are equivalently better than porous long-stem prostheses and alternatives for femoral-head replacement. The preferred design of those two depends on clinical conditions. The cemented long-stem is favorable for inactive elders with osteoporosis, and porously punched cementless short-stem design is suitable for patients with osteoporosis, while the porously punched cementless short-stem is favorable for those with a cement allergy. Clinically, the strength of this study is to enable preoperative strategy to provide acute correction and decrease procedure time

    Iron(III) bromide catalyzed bromination of 2-tert-butylpyrene and corresponding position-dependent aryl-functionalized pyrene derivatives

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    The present work probes the bromination mechanism of 2-tert-butylpyrene (1), which regioselectively affords mono-, di-, tri- and tetra-bromopyrenes, by theoretical calculation and detailed experimental methods. The bromine atom may be directed to the K-region (positions 5- and 9-) instead of the more reactive 6- and 8-positions in the presence of iron powder. In this process, FeBr₃ plays a significant role to release steric hindrance or lower the activation energy of the rearrangement. The intermediate bromopyrene derivatives were isolated and confirmed by ¹H NMR spectrometry, mass spectroscopy and elemental analysis. Further evidence on substitution position originated from a series of aryl substituted pyrene derivatives, which were obtained from the corresponding bromopyrenes on reaction with 4-methoxy-phenylboronic acid by a Suzuki–Miyaura cross-coupling reaction. All position-dependent aryl-functionalized pyrene derivatives are characterized by single X-ray diffraction, ¹H/¹³C NMR, FT-IR and MS, and offered straightforward evidence to support our conclusion. Furthermore, the photophysical properties of a series of compounds were confirmed by fluorescence and absorption, as well as by fluorescence lifetime measurements

    3,3′-(1,4-Phenyl­ene)bis­[2-(propyl­amino)­benzofuro[3,2-d]pyrimidin-4(3H)-one] ethanol disolvate

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    The title compound, C32H28N6O4·2C2H5OH, consists of two 2-(propyl­amino)­benzofuro[3,2-d]pyrimidin-4(3H)-one units connected, via one of the pyrimidine N atoms, to a bridging benzene ring in the 1,4 positions. Two ethanol solvent mol­ecules are also present. The main mol­ecule lies on a center of symmetry located at the center of the benzene ring. The fused-ring system of the benzofuro[3,2-d]pyrimidine moiety is nearly planar (r.m.s. deviation = 0.016 Å) and forms a dihedral angle of 78.21 (7)° with the central benzene ring. The crystal structure features O—H⋯O and N—H⋯O inter­actions. The C atoms of the propyl­amino side chain in the main mol­ecule and the ethyl group in the solvent mol­ecule are disordered over two positions, with site-occupancy factors 0.34:0.66 and 0.42:0.58, respectively

    Bis(1,3,4-thia­diazol-2-yl) disulfide

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    The title compound, C4H2N4S4, lies about a twofold rotation axis situated at the mid-point of the central S—S bond. Each of two thia­diazole rings is essentially planar, with an rms deviation for the unique thia­diazole ring plane of 0.0019 (7) Å. C—H⋯N hydrogen bonds link adjacent mol­ecules, forming zigzag chains along the c axis. In addition, these chains are connected by inter­molecular S⋯S inter­actions [S⋯S = 3.5153 (11) Å] , forming corrugated sheets, and further fabricate a three-dimensional supra­molecular structure by inter­molecular N⋯S contacts [S⋯N = 3.1941 (17) Å]

    Toward a uniform description of hydrogen bond and halogen bond: correlations of interaction energies with various geometric, electronic and topological parameters

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    Correlations between interaction energies and various structural parameters were established to reveal the differences between hydrogen bonds and halogen bonds.</p
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