检索结果-南通市图书馆

Journal of Mountain Science 2024年第9期21卷 2905-2917页

作者： LIU Yinpeng Mumtaz HAIDER david-darnor lawrence LI Tonglu SHEN Wei LI Ping College of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054China Observation and Research Station of Water Cycle and Geological Environment for the Chinese Loess Plateau Ministry of EducationZhengning 745399China

On 12th August 2015,a massive rapid long run-out rock landslide occurred in the Shanyang Vanadium Mine in Shaanxi Province,China,which claimed the lives of 65 *** heavy rainfalls,earthquakes,and mining blasts were recorded before the ***,the failure mechanism and the cause of the long run-out movement are always in *** this paper,we conducted a detailed field investigation,laboratory tests,block theory analysis,and numerical simulation to investigate the failure and long run-out mechanisms of the *** field investigation results show that the source material of the rock landslide is a huge dolomite wedge block bedding on siliceous shale *** compression tests indicate that the uniaxial compression strength of the intact dolomite is 130-140MPa and the dolomite shows a brittle failure *** to the progressive downward erosion of the gully,the dolomite rock bridge at the slope toe became *** the compression stress in the dolomite bridge increased to surpass its strength,the brittle failure of the bridge *** huge potential energy was released following the disintegration of the landslide,which led to the high acceleration of this rock *** 3D discrete element simulation results suggest that the low intergranular friction contributes to the long run-out movement of this rock landslide.

关键词： Rock landslide Gully erosion Long run-out Wedge block Discrete element method

Allogenic Stem Cell Transplantation and COVID-19 Antibodies: Mechanistic Insights and Recipient Concerns

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Immunology 2024年第2期14卷 16-32页

作者： Amna Umer Asma Umer Khayam Nasar Khan david lawrence Greene Umm E. Habiba Sabiha Shamim Pak-American Hospital Pvt. Ltd. Islamabad Pakistan R3 Medical Research LLC Scottsdale USA Bello Bio Labs and Therapeutics (SMC) Pvt. Ltd. Islamabad Pakistan Department of Biochemistry Rawalpindi Medical University Rawalpindi Pakistan Bello Bio LLC Scottsdale USA

Collecting umbilical cord stem cells is widely practiced due to its numerous benefits. Over the past decade, umbilical cord stem cells (UCSCs) have shown effectiveness in treating various conditions, such as bone pathologies, neuropsychiatry disorders, hereditary diseases, and metabolic disorders. However, factors like immunization affect the quantity and quality of cord harvesting. Studies suggest that antibodies from the mother pass through the umbilical cord to protect the infant against infections. Cleaning the umbilical cord before stem cell extraction is crucial to maintain sterility and cell integrity. Vaccinating a female donor, including for COVID-19, typically does not directly affect the stem cells. Although vaccines aim to trigger an immunological response, they generally do not affect the donor’s stem cells.

关键词： Vaccination Stem Cell Allogeneic COVID Antibodies

Involvement of eicosanoids in the pathogenesis of pancreatic cancer: the roles of cyclooxygenase-2 and 5-lipoxygenase

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第31期20卷 10729-10739页

作者： lawrence M Knab Paul J Grippo david J Bentrem Department of Surgery Northwestern University Feinberg School of Medicine Robert H Lurie Comprehensive Cancer Center Northwestern University Jesse Brown VA Medical Center

The interplay between inflammation and cancer progression is a growing area of research. A combination of clinical, epidemiological, and basic science investigations indicate that there is a relationship between inflammatory changes in the pancreas and neoplastic progression. Diets high in ω-6 polyunsaturated fatty acids provide increased substrate for arachidonic acid metabolism by cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) to form eicosanoids. These eicosanoids directly contribute to pancreatic cancer cell proliferation. Both COX-2 and 5-LOX are upregulated in multiple cancer types, including pancreatic cancer. In vitro studies using pancreatic cancer cell lines have demonstrated upregulation of COX-2 and 5-LOX at both the mRNA and protein levels. When COX-2 and 5-LOX are blocked via a variety of mechanisms, cancer cell proliferation is abrogated both in vitro and in vivo. The mechanism of COX-2 has been shown to include effects on apoptosis as well as angiogenesis. 5-LOX has been implicated in apoptosis. The use of COX-2 and 5-LOX inhibitors in clinical studies in patients with pancreatic cancer has been limited. Patient enrollment has been restricted to those with advanced disease which makes evaluation of these drugs as chemopreventive agents difficult. COX-2 and 5-LOX expression have been shown to be present during the early neoplastic changes of pancreatic cancer, well before progression to invasive disease. This indicates that the ideal role for these interventions is early in the disease process as preventive agents, perhaps in patients with chronic pancreatitis or hereditary pancreatitis.

关键词： Arachidonic acid Eicosanoid Cyclooxygenase-2 5-lipoxygenase Pancreatic cancer Inflammation

pH-mediated synthesis of monodisperse gold nanorods with quantitative yield and molecular level insight

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2021年第4期14卷 1167-1174页

作者： Reese Gallagher Xing Zhang Anthony Altomare david lawrence Jr. Nicholas Shawver Ninh Tran Melanie Beazley Gang Chen Department of Chemistry University of Central FloridaOrlando32816USA

Although gold nanorods(GNRs)have been produced with different dimensions and aspect ratios,the current synthesis methods through seed-mediated growth are far from ideal,for instance,the quality(rod yield)and the quantity(gold conversion)cannot be simultaneously *** critically,there is no molecular level understanding of the growth ***,we solved the problem by employing the stoichiometric ratio of reactants and tuning the reactivity of the reductant through adjusting the initial pH value of the growth solution to achieve both good quality and high quantity *** also extended our strategy to other enols besides ascorbic acid,such as phenolic compounds,and found that the optimal pH for GNRs synthesis depends on the structure of the individual *** mechanistic insight greatly enriches the toolbox of reductants for GNRs growth and makes it possible to synthesize GNRs at both acidic and basic *** interesting phenomenon is that for most of the phenolic compounds we tested,the morphology of the final products follows the same sphere-rod-sphere trend as the initial pH value of the reaction increases,whether it is under acidic or basic conditions,which cannot be explained by any previously proposed *** effect of pH is mainly attributed to the regulation of the reduction potential of the reductants,and thus the reaction rate.A model has been proposed to explain the dependence of anisotropic growth of GNRs on the concentration gradient of reactants around the seeds,which is decided by both the reaction rate and diffusion rate.

关键词： gold nanorods gold conversion yield shape homogeneity pH value reduction potential concentration gradient

Growing Operational Use of FY-3 Data in the ECMWF System

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2021年第8期38卷 1285-1298页

作者： Niels BORMANN david DUNCAN Stephen ENGLISH Sean HEALY Katrin LONITZ Keyi CHEN Heather lawrence Qifeng LU European Centre for Medium-range Weather Forecasts Reading RG29AXUnited Kingdom International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of the Chinese Academy of Sciences Beijing 100049China Department of Atmospheric Sciences Chengdu University of Information TechnologyChengdu 610225China National Satellite Meteorological Centre China Meteorological AdministrationBeijing 10081China

This paper reviews the data quality and impact of observations from the FY-3 satellite series used operationally in the ECMWF system. This includes data from the passive microwave radiometers MWHS-1, MWHS-2 and MWRI, as well as observations from the radio occultation receiver GNOS. Evaluations against background equivalents show that the quality of the observations is broadly comparable to that of similar instruments on other polar-orbiting satellites, even though biases for the passive microwave observations can be somewhat larger and more complex for some channels. An observing system experiment shows that the FY-3 instruments jointly contribute significantly to the forecast skill in the ECMWF system. Positive impact of up to 2% is seen for most variables out to the day-2 forecasts over hemispheric scales, with significant benefits for total column water vapor or for temperature and wind in the stratosphere out to day 4.

关键词： FY-3 satellite series assimilation forecast impact calibration/validation

CO oxidation over ceria supported Au_(22) nanoclusters: Shape effect of the support

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2018年第6期29卷 795-799页

作者： Zili Wu david R.Mullins lawrence F.Allard Qianfan Zhang Laisheng Wang Chemical Science Division and Center for Nanophase Materials Sciences Oak Ridge National Laboratory Materials Science and Technology Division Oak Ridge National Laboratory Department of Chemistry Brown University

Gold（Au） nanoclusters have recently emerged as ideal models for understanding Au catalysis, because the nanosized Au particles have precise atomic numbers and uniform size. In this work, we studied for the first time the support shape effect on the catalysis of Au nanoclusters by using CO oxidation as a model reaction. Au22（L8）6（L = 1,8-bis（diphenylphosphino） octane） nanoclusters were supported on CeO2 rods or cubes, then pretreated at different temperatures（up to 673 K）, allowing the gradual removal of the organic phosphine ligands. CO oxidation test over these differently pretreated samples shows that CeO2 rods are much better supports than cubes for Au22 nanoclusters in enhancing the reaction rate. In situ IR spectroscopy coupled with CO adsorption indicates that the shape of CeO2 support can impact the nature and quantity of exposed Au sites, as well as the efficiency of organic ligand removal. Although CeO2 rods are helpful in exposing a greater percentage of total Au sites upon ligands removal, the percentage of active Au sites（denoted by Au d＋, 0 〈 d 〈 1） is lower than that on CeO2 cubes. The in situ extended X-ray absorption spectroscopy（EXAFS） and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM） results show that the Au nanoclusters bound more strongly to the CeO2 rods than to the cubes where the Au nanoclusters show more sintering. Considering the typical redox mechanism for CO oxidation over supported Au nanoclusters and nanoparticles, it is concluded that the reactivity of the lattice oxygen of CeO2 is the determining factor for CO oxidation over Au22/CeO2. CeO2 rods offer more reactive lattice oxygen and abundant oxygen vacancies than the cubes and thus make the rods a superior support for Au nanoclusters in catalyzing low temperature CO oxidation.

关键词： Gold nanoclusters Ceria Ligands Support shape CO oxidation

Microstructure and mechanical properties of Ti-6Al-4V-5% hydroxyapatite composite fabricated using electron beam powder bed fusion

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第2期35卷 309-321页

作者： César A.Terrazas lawrence E.Murr Diego Bermudez Edel Arrieta david A.Roberson Ryan B.Wicker W.M.Keck Center for 3D Innovation The University of Texas at El PasoEl PasoTX 79968USA Department of Mechanical Engineering The University of Texas at El PasoTX 79968USA Department of Metallurgical Materials and Biomedical EngineeringThe University of Texas at El PasoTX 79968USA

A novel, Ti-6 Al-4 V(Ti64)/Hydroxyapatite(HA at 5% by weight concentration) metal/ceramic composite has been fabricated using electron beam powder bed fusion(EPBF) additive manufacturing(AM): specifically, the commercial electron beam melting(EBM?) process. In addition to solid Ti64 and Ti64/5% HA samples, four different unit cell(model) open-cellular mesh structures for the Ti64/5% HA composite were fabricated having densities ranging from 0.68 to 1.12 g/cm^3, and corresponding Young's moduli ranging from 2.9 to 8.0 GPa, and compressive strengths ranging from ~3 to 11 MPa. The solid Ti64/5%HA composite exhibited an optimal tensile strength of 123 MPa, and elongation of 5.5% in contrast to a maximum compressive strength of 875 MPa. Both the solid composite and mesh samples deformed primarily by brittle deformation, with the mesh samples exhibiting erratic, brittle crushing. Solid, EPBF-fabricated Ti64 samples had a Vickers microindentation hardness of 4.1 GPa while the Ti64/5%HA solid composite exhibited a Vickers microindentation hardness of 6.8 GPa. The lowest density Ti64/5%HA composite mesh strut sections had a Vickers microindentation hardness of 7.1 GPa. Optical metallography(OM) and scanning electron microscopy(SEM) analysis showed the HA dispersoids to be highly segregated along domain or grain boundaries, but homogeneously distributed along alpha(hcp) platelet boundaries within these domains in the Ti64 matrix for both the solid and mesh composites. The alpha platelet width varied from ~5 μm in the EPBF-fabricated Ti64 to ~1.1 m for the Ti64/5%HA mesh strut. The precursor HA powder diameter averaged 5 μm, in contrast to the dispersed HA particle diameters in the Ti64/5%HA composite which averaged 0.5 m. This work highlights the use of EPBF AM as a novel process for fabrication of a true composite structure, consisting of a Ti64 matrix and interspersed and exposed HA domains, which to the authors' knowledge has not been reported before. The results also illu

关键词： Hydroxyapatite (HA) Metal-matrix ceramic composites Open-cellular (mesh) structures Electron-beam powder bed fusion (EPBF) Additive manufacturing (AM) Mechanical properties Microstructure characterization

A system for probing Casimir energy corrections to the condensation energy

在线全文

学校读者我要写书评

暂无评论

Microsystems & Nanoengineering 2020年第1期6卷 1-12页

作者： Diego Perez-Morelo Alexander Stange Richard W.Lally lawrence K.Barrett Matthias Imboden Abhishek Som david K.Campbell Vladimir A.Aksyuk david J.Bishop Department of ECE Boston UniversityBostonMA 02215USA Physical Measurement Laboratory National Institute of Standards and TechnologyGaithersburgMD 20899USA Institute for Research in Electronics and Applied Physics&Maryland NanoCenter University of MarylandCollege ParkMD 20742USA Division of MSE Boston UniversityBostonMA 02215 USA 54K-MEMS Sarl Rue des Lavannes 172072 St BlaiseSwitzerland Department of Physics Boston UniversityBostonMA 02215USA Department of ME Boston UniversityBostonMA 02215USA Department of BME Boston UniversityBostonMA 02215USA

In this article,we present a nanoelectromechanical system(NEMS)designed to detect changes in the Casimir *** Casimir effect is a result of the appearance of quantum fluctuations in an electromagnetic *** experiments have used nano-or microscale parallel plate capacitors to detect the Casimir force by measuring the small attractive force these fluctuations exert between the two *** this new set of experiments,we aim to directly detect the shifts in the Casimir energy in a vacuum due to the presence of the metallic parallel plates,one of which is a superconductor.A change in the Casimir energy of this configuration is predicted to shift the superconducting transition temperature(T_(c))because of the interaction between it and the superconducting condensation *** our experiment,we take a superconducting film,carefully measure its transition temperature,bring a conducting plate close to the film,create a Casimir cavity,and then measure the transition temperature *** expected shifts are smaller than the normal shifts one sees in cycling superconducting films to cryogenic temperatures,so using a NEMS resonator in situ is the only practical way to obtain accurate,reproducible *** a thin Pb film and opposing Au surface,we observe no shift in T_(c)>12µK down to a minimum spacing of~70 nm at zero applied magnetic field.

关键词： cycling energy film

Hybrid post-processing effects of magnetic abrasive finishing and heat treatment on surface integrity and mechanical properties of additively manufactured Inconel 718 superalloys

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第33期128卷 10-21页

作者： Kun Li Ruijin Ma Ming Zhang Wen Chen Xiaobin Li david Z.Zhang Qian Tang lawrence E.Murr Jinfeng Li Huajun Cao State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing 400044China Chongqing Key Laboratory of Metal Additive Manufacturing(3D Printing) Chongqing UniversityChongqing 400044China College of Engineering Mathematics and Physical SciencesUniversity of ExeterNorth Park RoadExeter EX44QFUK W.M.Keck Center for 3D Innovation University of Texas at El PasoEl PasoTX 79968USA Department of Metallurgical Materials and Biomedical EngineeringUniversity of Texas at El PasoEl PasoTX 79968USA Institute of Materials China Academy of Engineering PhysicsMianyang 621908China

Desired microstructure and surface integrity are critical to achieving the high performance of additively manufactured *** the present work,the hybrid post-processes of magnetic abrasive finishing(MAF)and post-heat treatment(HT)were applied to the additively manufactured Inconel718 *** hybrid effects and influencing mechanism on the surface quality and mechanical properties of the additively manufactured samples have been studied *** results show that the MAF process effectively reduces the surface roughness by more than an order of magnitude due to the flexibility and geometric consistency of the magnetic particles and abrasives with the finished *** proper sequence of MAF and HT obtains enhanced mechanical properties for the homogenized-MAF-aged sample with the yield strength of 1147 MPa,the ultimate tensile strength of 1334 MPa,and the elongation of 22.9%,which exceeds the standard wrought *** surface integrity,compressive residual stress field,and grain refinement induced by the MAF and subsequent aging heat treatment increase the cracking resistance and delay the fracture failure,which significantly benefits the mechanical *** MAF process combined with proper post-heat treatment provides an effective pathway to improve the mechanical properties of additively manufactured materials.

关键词： Magnetic abrasive finishing Additive manufacturing Inconel 718 Microstructure–property relationship Heat treatment

Intermediate accounting J. david Spiceland, James F. Sepe, lawrence A. Tomassini 3rd ed.

在线全文

学校读者我要写书评

暂无评论