130 research outputs found
Assessing the scientific integrity of the collected work of one author or author group
No full textObjectives: No published methods for research integrity review include both statistical techniques applied to groups of randomized trials and individual assessment of papers. We propose a method based on practical experience of investigating data integrity across the collected papers of an author or author group. Study Design and Setting: We report our approach to investigating the collected papers of an author or author group suspected of academic misconduct. Results: In the investigation of the work of an author or author group, we recommend a systematic search for the work of the involved authors in PubMed, Google Scholar, and the Retraction Watch database, as well as a search of trial registries for unpublished clinical trials. Summary information from studies should be tabulated to assess consistency between study registration, execution, and publication. Each paper should be investigated for unfeasible features of the governance, methodology, execution, results, and reporting of the study. Pairwise comparison of baseline and outcome tables between papers may reveal data duplication or unfeasibly large differences between baseline characteristics in similar studies. Assessment of baseline characteristics from multiple randomized trials using Carlisle’s method can determine whether the data are consistent with a properly executed randomization process, as can checking whether reported baseline characteristics follow expected patterns for random variables such as Benford’s law. If serious concerns are raised, a more thorough investigation should be performed by journals, publishers, and institutions. Conclusion: These methods provide a systematic and reproducible way to assess the collected work of an author or group of authors.Jeremy Nielsena, Esmée M. Bordewijka, Lyle C. Gurrinc, Siddharth Shivanthad, Madeline Flanagana, Sue Liud, May M. Linna, Kelly X. Zhoua, Rik van Eekelenb, Nicholas J.L. Browne, Jim Thorntonf, Ben W. Mo
Practical use of electric networks to simulate or predict seiche conditions in harbors
No full textThe successful design of a marina with respect to seiche conditions presupposes two categories of knowledge. Of these the more difficult to obtain is an adequate description of the local long period wave environment. Somewhat easier, but equally important, is a detailed knowledge of the responses various basin configurations present as a result of irradiation under some standardized wave environment. One such environment would be that provided by sinusoidal waves issuing from a distant line source maintained at unit amplitude, constant frequency; and fixed direction. Independently varying both the source orientation and frequency and measuring resulting responses at fixed locations is a procedure common to many wave scattering experiments. It is generally supposed that these scattered wave fields later may be superimposed. This will be the case if linear equations adequately describe the wave motion, as will be assumed here. However, in a medium with spatially inhomogeneous propagation properties, there is no unambiguous distinction between the incident and scattered waves; only in the case of uniform propagation are the real and imaginary parts of ei(k.x-wt) identical, apart from a translation in the direction of k. Interfering reflections and other scattering effects due to variable depth cannot be eliminated or treated separately from peripheral reflections. The complexity inherent in most practical situations requires that some sort of model be used
A nonlinear river meandering model and its incorporation in a landscape evolution model
No full textThesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1998.Includes bibliographical references (p. 267-277).A topographic steering river meandering (TSRM) model based on continuity of a simplified flow field through bends is developed. The equilibrium coupling between helical flow and sediment transport, as in Ikeda [1989] determines downstream variation of transverse bed slope. The model tests the hypothesis that meander development patterns can be captured under the assumptions: (a) bank shear stress arises from forces associated with topographically induced convective accelerations; (b) turbulent boundary layer dissipation of these forces at the banks is sufficiently represented by gaussian smoothing at a parameterized scale; and (c) lateral migration of the channel is proportional to bank shear stress. The resulting TSRM model produces realistic complex meander patterns and scroll bar-like topography. Model compound bend formation is compared to a field case and found to arise from the nonlinear interaction of bank roughness and channel hydraulics scales. When the latter is short relative to the former, maximum bank shear stress occurs early in the bend and leads to compound bend formation. New statistical stream sinuosity and spatial coordinate variation measures are applied to both natural and model streams and reveal secondary sinuosities arising from compound bend formation in both cases. Scroll bar topography and channel bank roughness are studied in the field to compare natural and model mechanisms. A channel-hillslope integrated landscape development (CHILD) model incorporates the TSRM model. The CHILD model represents the landscape as an irregular, Delaunay triangulated mesh of landscape nodes that may be moved, deleted, or added to accommodate meandering channels that are in general discretized at different spatial resolution than the surrounding landscape. The interactions among meandering, bank erodibility's bank height dependence, and uplift rate in a detachment-limited river valley are examined. An equilibrium landscape adjusts to the onset of meandering and approaches a new dynamic equilibrium. For the detachment-limited case, the hypothesis that meandering is more active when uplift is quiescent is rejected. When bank erodibility's bank height dependence is greater, bend scale sinuosity is smaller, but the tendency toward multi-bend loop formation is reinforced.by Stephen Thomas Lancaster.Ph.D
Analysis on Coordinated Operation Benefits of Wind Power with Carbon Capture Power Plant
No full textTransforming growth factor-beta 1 and TbetaRII/Smad3 signalling pathway regulates the vascular endothelial growth factor expression of tumour-associated macrophages in oral squamous cell carcinoma
No full textThe Analysis of Bending Causes and Optimized Control Measures in Hydrogenation Air-Cooler System
No full textAbstractIn order to confirm the source of fouling and corrosion type, the process analysis is conducted based on the bending tubes of hydro-cracking reactor effluent air coolers (REAC) in a refinery. The process of sediment deposition was analyzed by using the CFD technology, and the critical condition of bending deformation and instability of tubes was determined via stress analysis. On this base, reasons of bending deformation in air cooler system and the targeted control measures were determined. The results showed that corrosion system of H2S-NH3-H2O existing in the cooling and separation process of hydrogenation reactor effluent stream, which would result in high temperature corrosion of H2S/H2 and erosion-corrosion of NH4HS solution. A large amount of corrosion products located at the end of tubes, which could block the air coolers when at a low flow velocity. In the air-cooler system, the temperature and force distribution were uneven when some part of pipes were blocked. Once the number of blocked pipes exceeds 9, the pipe bundles were diastrophic. The failure risk of bending deformation in reactor effluent air coolers (REAC) system could reduce, when the generation and deposition of corrosion products should be retarded, amount of water injection should be increased, desulfidation in recycle hydrogen should be strengthened and the design of REAC should be optimized
Two-dimensional buffer breaks substrate limit in III-nitrides epitaxy
No full textExpanding the diversity of substrate materials for the growth of single-crystalline films enables the heterointegration of electronic and optoelectronic devices in modern semiconductor industry. However, the substrate materials are restricted to those having matched single-crystalline lattices with the epilayers, thereby making the use of non-single-crystalline substrates infeasible. Here, we report an epitaxy strategy for the wafer-scale growth of high-quality single-crystalline gallium nitride (GaN) on an amorphous silicon dioxide (SiO2) substrate. We achieve this result through a chemical bond transition, converting multilayer molybdenum disulfide (MoS2) to molybdenum nitride (MoN), which serves as a buffer layer to engineer a preferred orientation for the epitaxy of the overlying GaN film. Using this method, we also demonstrate the growth of an AlGaN/AlN/GaN heterostructure with high electron mobility exceeding 2000 square centimeters per volt per second. The resultant high-electron-mobility transistors exhibit subthreshold swing, on/off ratio, and threshold voltage comparable to those commercial devices.Z.Z. acknowledges the national Key Research and development Program of china(no. 2023YFB3610300), the national nature Science Foundation of china (no. 62274083), thenatural Science Foundation of Jiangsu Province (no. BK20232042), and the FundamentalResearch Funds for the central Universities (no. XJ2024005803. K.X. acknowledges the nationalnature Science Foundation of china (no. 62204073), the Fundamental Research Funds for thecentral Universities (no. JZ2023hGtB0273), and national nature Science Foundation of AnhuiProvince (no. 2208085QF210). X.W. acknowledges the national Key Research anddevelopment Program of china (no. 2022YFA1402404) and the national nature ScienceFoundation of china (no. 62274085). X.W. and B.l. acknowledge the national nature ScienceFoundation of china (no. t2221003). R.Z and B.l. acknowledge the collaborative innovationcenter of Solid-State lighting and energy-Saving electronics. K.O. and h.n.A. acknowledge theKing Abdullah University of Science and technology (KAUSt). Author contributions: Z.Z. andX.X. conceived the idea of the epitaxy of Gan on the amorphous substrate. Z.Z., R.Z., and B.l.supervised the project. Y.S. performed data collection and analysis. X.X. prepared the MoS2 andMon buffer layers and performed XRd and AFM of these films. K.X., Z.Z., and Z.J. conductedthe epitaxial growth of iii- nitrides using MOvPe. G.F. and K.X. performed the AFM and XRdmeasurements of the epitaxial nitrides. Y.W. and S.d. performed dFt calculation and dataanalysis. Y.S. performed teM characterization and was responsible for the fabrication andcharacterization of heMt device and hall bar device. F.Z. grew the gate dielectric layer. h.G.and d.c. helped with data analysis of the fabricated heMt. X.Z. and X.F.W. performed the hallmeasurement at different temperatures and data analysis. t.t., K.O., X.R.W., and h.n.A. providedresources for the experiments and commented on the manuscript. Z.Z. and Y.S. cowrote themanuscript. All authors contributed to the discussion of the results. Competing interests: theauthors declare that they have no competing interests. Data and materials availability: Alldata needed to evaluate the conclusions in the paper are present in the paper and/or theSupplementary Materials
Experimental research on dynamic mechanical properties of PZT ceramic under hydrostatic pressure
No full textAn experimental technique for initially applied hydrostatic pressure in specimens subjected to axial impact has been developed to study the dynamic mechanical properties of materials. The technique was employed for the purpose of examining the dynamic mechanical properties of lead zirconate titanate (PZT) at zero to 15 MPa hydrostatic pressures. Experimental results unambiguously exhibit the ductile behavior of PZT when hydrostatic pressure is involved. The compressive strength is demonstrated sensitive to the initial hydrostatic pressure and the strain-rate. The fracture modes are analyzed by means of scanning electron microscopy (SEM). Moreover, a failure criterion based on Mohr-Coulomb failure theory is suggested to explain the brittle and ductile failure of PZT. (C) 2011 Elsevier B.V. All rights reserved.Nanoscience & NanotechnologyMaterials Science, MultidisciplinaryMetallurgy & Metallurgical EngineeringSCI(E)EI3ARTICLE216463-646852
Dynamic behavior of a Zr-based metallic glass at cryogenic temperature
No full textThe dynamic behavior of a Zr-based bulk metallic glass at cryogenic temperature is investigated by a miniaturized split Hopkinson pressure bar apparatus As that at room temperature the failure stress decreases suddenly and then tends to hold steady along with increasing strain rate at cryogenic temperature but the strain rate regime corresponding to the sudden decrease of the failure stress moves up The failure stress also increases along with decreasing temperature whereas there is no obvious change for the plasticity (C) 2010 Elsevier Ltd All rights reservedhttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000285122300017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Chemistry, PhysicalMaterials Science, MultidisciplinaryMetallurgy & Metallurgical EngineeringSCI(E)EI7ARTICLE1109-1121
A one-pot-three-step route to triazolotriazepinoindazolones from oxazolino-2H-indazoles
No full textA one-pot-three-step method has been developed for the conversion of oxazolino-2H-indazoles into triazolotriazepinoindazolones with three points of diversity. Step one of this process involves a propargyl bromide-initiated ring opening of the oxazolino-2H-indazole (available by the Davis-Beirut reaction) to give an N1-(propargyl)-N2-(2-bromoethyl)-disubstituted indazolone, which then undergoes -CH2Br → -CH2N 3 displacement (step two) followed by an uncatalyzed intramolecular azide-alkyne 1,3-dipolar cycloaddition (step three) to form the target heterocycle. Employing 7-bromooxazolino-2H-indazole allows for further diversification through, for example, palladium-catalyzed coupling chemistry, as reported here. © 2012 American Chemical Society.Abouzid KAM, 2003, ARCH PHARM RES, V26, P1; Angela R.K., 2012, ORG LETT, V14, P1804; Avila B, 2011, ORG LETT, V13, P1060, DOI 10.1021-ol103108z; Brodie MJ, 2009, EPILEPSIA, V50, P1899, DOI 10.1111-j.1528-1167.2009.02160.x; Butler JD, 2008, J ORG CHEM, V73, P234, DOI 10.1021-jo702067z; Callam CS, 2001, J CHEM EDUC, V78, P947; Cappelli A, 2008, J MED CHEM, V51, P2137, DOI 10.1021-jm7011563; Cerecetto H, 2005, MINI-REV MED CHEM, V5, P869, DOI 10.2174-138955705774329564; Conrad WE, 2011, ORG LETT, V13, P3138, DOI 10.1021-ol2010424; Dandapani S, 2010, CURR OPIN CHEM BIOL, V14, P362, DOI 10.1016-j.cbpa.2010.03.018; Donald JR, 2011, ORG LETT, V13, P852, DOI 10.1021-ol1028404; Donald MB, 2010, ORG LETT, V12, P2524, DOI 10.1021-ol100751n; Gupta M, 2011, EUR J MED CHEM, V46, P631, DOI 10.1016-j.ejmech.2010.11.043; Hann MM, 2004, CURR OPIN CHEM BIOL, V8, P255, DOI 10.1016-j.cbpa.2004.04.003; Hartwig J.F., 1998, ANGEW CHEM INT EDIT, V37, P2046, DOI DOI 10.1002-(SICI)1521-3773(19980817)37:152046::AID-ANIE20463.0.CO; Huang LJ, 2006, BIOORGAN MED CHEM, V14, P528, DOI 10.1016-j.bmc.2005.08.032; Huuf B.E., 1997, ORG SYN, V75, P53; Kawanishi N, 2006, BIOORG MED CHEM LETT, V16, P5122, DOI 10.1016-j.bmcl.2006.07.026; Khalil AM, 2009, EUR J MED CHEM, V44, P4448, DOI 10.1016-j.ejmech.2009.06.003; Kharb R, 2011, J ENZYM INHIB MED CH, V26, P1, DOI 10.3109-14756360903524304; Kurth MJ, 2005, J ORG CHEM, V70, P1060, DOI 10.1021-jo048153i; Lipinski CA, 1997, ADV DRUG DELIVER REV, V23, P3, DOI 10.1016-S0169-409X(96)00423-1; Majumdar K. C., 2011, SYNTHESIS-STUTTGART, V23, P3767; Mills AD, 2007, J COMB CHEM, V9, P171, DOI 10.1021-cc060109o; Mills AD, 2006, J ORG CHEM, V71, P2687, DOI 10.1021-jo0524831; Miyura N., 1995, CHEM REV, V95, P2457; Oakdale JS, 2009, ORG LETT, V11, P2760, DOI 10.1021-ol900891s; Oliva AI, 2008, ORG LETT, V10, P1617, DOI 10.1021-ol800291t; Fletcher SR, 2006, BIOORG MED CHEM LETT, V16, P2872, DOI 10.1016-j.bmcl.2006.03.004; Ryng S, 2005, PHARMACOL REP, V57, P195; Sankaran M, 2010, BIOORG MED CHEM LETT, V20, P7147, DOI 10.1016-j.bmcl.2010.09.018; Solano D.M., 2010, J ORG SYNTH, V87, P339; Tan DS, 2005, NAT CHEM BIOL, V1, P74, DOI 10.1038-nchembio0705-74; Walters WP, 2003, NAT REV DRUG DISCOV, V2, P259, DOI 10.1038-nrd1063; Wang H, 2006, CANCER RES, V66, P9722, DOI 10.1158-0008-5472.CAN-05-4602; Wolfe JP, 2000, J ORG CHEM, V65, P1144, DOI 10.1021-jo9916986; Wolfe JP, 1998, ACCOUNTS CHEM RES, V31, P805, DOI 10.1021-ar960065010111
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