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Development of current-induced scour beneath elevated subsea pipelines

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Journal of Ocean Engineering and Science 2018年第4期3卷 265-281页

作者： jun y.lee Alexander L.Forrest Fauzi A.Hardjanto Shuhong Chai Remo Cossu Zhi Q.Leong National Centre for Maritime Engineering and Hydrodynamics Australian Maritime CollegeUniversity of TasmaniaLocked Bag 1395Launceston Tasmania 7250Australia Department of Civil and Environmental Engineering University of California-DavisDavisCA 95616United States School of Civil Engineering University of QueenslandSt Lucia Queensland 4072Australia

When scour occurs beneath a subsea pipeline and develops to a certain extent,the pipeline may experience vortex-induced vibrations,through which there can be a potential accumulation of fatigue ***,when a pipeline is laid on an uneven seabed,certain sections may have an elevation with respect to the far-field seabed,e o,at which the development of scour would *** work focused on predicting the development of the scour depth beneath subsea pipelines with an elevation under steady flow conditions.A range of pipe elevation-to-diameter ratios(i.e.0≤e o/D≤0.5)have been considered for laboratory experiments conducted in a sediment *** corresponding equilibrium scour depths and scour time scales were obtained;experimental data from published literature have been collected and added to the present study to produce a more complete analysis *** correlation between existing empirical equations for predicting the time scale and the experimental data was assessed,resulting in a new set of constants.A new manner of converting the scour time scale into a non-dimensional form was found to aid the empirical equations in attaining a better correlation to the experimental ***,a new empirical equation has also been proposed in this work,which accounts for the influence of e o/D on the non-dimensional scour time *** was found to have the best overall correlation with the experimental ***,full-scale predictions of the seabed gaps and time scales were made for the Tasmanian Gas Pipeline(TGP).

关键词： Scour time scale Equilibrium scour depth Subsea pipelines Pipe elevation Steady currents.

Effect of Wave Nonlinearity on the Instantaneous Seabed Liquefaction

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China Ocean Engineering 2024年第1期38卷 93-103页

作者： WANG Zhao-jun SUI Ti-ti ZHANG Chi PAN jun-ning Key Laboratory of Port Waterway and Sedimentation Engineering of the Ministry of TransportNanjing Hydraulic Research InstituteNanjing 210024China Key Laboratory of Coastal Disaster and Protection(Hohai University) Ministry of EducationNanjing 210098China The National Key Laboratory of Water Disaster Prevention Nanjing 210098China

The nonlinear variation of wave is commonly seen in nearshore area,and the resulting seabed response and liquefaction are of high concern to coastal *** this study,an analytical formula considering the nonlinear wave skewness and asymmetry is adopted to provide wave pressure on the seabed *** liquefaction depth attenuation coefficient and width growth coefficient are defined to quantitatively characterize the nonlinear effect of wave on seabed *** on the 2D full dynamic model of wave-induced seabed response,a detailed parametric study is carried out in order to evaluate the influence of the nonlinear variation of wave loadings on seabed ***,new empirical prediction formulas are proposed to fast predict the maximum liquefaction under nonlinear *** indicate that(1)Due to the influence of wave nonlinearity,the vertical transmission of negative pore water pressure in the seabed is hindered,and therefore,the amplitude decreases significantly.(2)In general,with the increase of wave nonlinearity,the liquefaction depth of seabed decreases *** under asymmetric and skewed wave loading,the attenuation of maximum seabed liquefaction depth is the most significant among all the nonlinear wave ***,highly skewed wave can cause the liquefaction depth of seabed greater than that under linear wave.(3)The asymmetry of wave pressure leads to the increase of liquefaction width,whereas the influence of skewedness is not significant.(4)Compared with the nonlinear waveform,seabed liquefaction is more sensitive to the variation of nonlinear degree of wave loading.

关键词： nonlinear wave seabed response seabed liquefaction numerical simulation liquefaction prediction

Chemical and mechanical properties of stainless, environment-friendly, and nonflammable Mg alloys (SEN alloys): A review

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Journal of Magnesium and Alloys 2024年第3期12卷 841-872页

作者： Jong Un lee Hyun Ji Kim Sang-Cheol Jin ye Jin Kim young Min Kim Bong Sun you jun Ho Bae Sung Hyuk Park Advanced Metals Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Metallurgical Engineering Kyungpook National UniversityDaegu 41566Republic of Korea Missile Research Institute Agency for Defense DevelopmentDaejeon 34060Republic of Korea

This review article provides overall understanding of stainless,environment-friendly,and nonflammable Mg alloys(SEN alloys)recently developed at the Korea Institute of Materials *** alloys are produced by adding small amounts of Ca and y(eachys,resulting in exceptional ignition and corrosion resistances and impressive mechanical *** main advantages of SEN alloys are as follows.(1)A dense multi-oxide layer of SEN alloys comprising MgO,CaO,and y_(2)O_(3) impedes the outward dispersion of Mg vapor and the inward penetration of O_(2) during oxidation,thereby enhancing the oxidation and ignition resistances.(2)The presence of Ca-and y-based second-phase particles in SEN alloys can enhance their corrosion resistance because Ca-containing particles prevent the spread of corrosion,and the replacement of Al-containing particles with less noble ones containing y(e.g.,Al–Mn–y or Al–y particles)retards corrosion.(3)The addition of minor amounts of Ca and y renders excellent mechanical properties due to improved strengthening *** enhanced properties are attributed to more pronounced dynamic recrystallization and grain refining behaviors caused by the second-phase particles during extrusion.(4)Despite the presence of various types of second-phase particles,the fatigue properties of SEN9 alloys are similar to those of commercial AZ91 alloys.(5)Simultaneous introduction of Ca and y suppresses the formation of Mg17Al12 discontinuous precipitates during aging,leading to the enhanced elongation of aged SEN alloys.(6)Adding mischmetal into the SEN9 alloy leads to a six-fold enhancement in ***,the studies conducted on SEN alloys demonstrate their excellent ignition and corrosion resistances and mechanical properties,which broaden the industrial applications of Mg alloys by addressing their inherent weaknesses.

关键词： SEN magnesium alloy Corrosion resistance Ignition resistance Mechanical properties Extrudability.

From dichotomy to diversity:deciphering the multifaceted roles of tumor-associated macrophages in cancer progression and therapy

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Cancer Biology & Medicine 2024年第2期21卷 132-138页

作者： Xiumei Wang jun Chen Guangshuai Jia Department of Immunology and Microbiology Zhongshan School of MedicineSun Yat-sen UniversityGuangzhou 510080China Jinfeng Laboratory Chongqing 401329China GMU-GIBH Joint School of Life Sciences Guangzhou Medical UniversityGuangzhou 510182China

Macrophages are innate immune cells that are ubiquitously distributed throughout the vertebrate *** orchestrate sophisticated processes in development,homeostasis,immunity,and *** residing in tumor tissues are commonly known as tumor-associated macrophages(TAMs)and promote or inhibit tumor growth depending on the activation state2.

关键词： immunity homeostasis tumor

Evolution of copper species during heat treatment and its effect on CO oxidation reaction on CuCeZrO_(y) catalyst synthesized by a facile solvent-free route

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Journal of Rare Earths 2024年第4期42卷 660-667页

作者： Guangying Fu Dongsen Mao jun yu Qiangsheng Guo School of Chemical and Environmental Engineering Shanghai Institute of TechnologyShanghai21418 China The ZeoMat Group Qingdao Institute of Bioenergy and Bioprocess TechnologyCASQingdao26611China

Several ternary oxides CuCeZrO_(y)(CCZ)were synthesized by a facile grinding method followed by calcination at high temperatures,and used as catalysts for CO oxidation at low *** influences of calcination temperature(400-600℃)on the physicochemical properties of the assynthesized ternary oxides were investigated by thermogravimetric analysis/differential scanning calorimetry(TGA/DSC),X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman,inductively coupled plasma-optical emission spectrometry(ICP-OES),N_(2) adsorption,H_(2)-temperature programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)*** results show that the increase in calcination temperature from 400 to 500℃is conducive to the high dispersion of CuOx on catalyst surface and the incorporation of Cu species into the support to form the Cu-Ce-Zr-O solid *** raising of calcination temperature from 500 to 600℃,however,leads to the segregation of Cu species from the solid solution to aggregate on support surface and growth of highly dispersed CuOx *** highest catalytic activity is acquired over the CCZ calcined at 500℃,which can be ascribed to the largest contents of Cu+species and oxygen vacancies owing to the formation of the maximum amount of Cu-Ce-Zr-O solid solution.

关键词： CuCeZrO_(y)catalyst co oxidation Calcination temperature Grinding method Oxalate precursor Rare earths

Sharp bilinear decomposition for products of both anisotropic Hardy spaces and their dual spaces with its applications to endpoint boundedness of commutators

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Science China Mathematics 2024年第9期67卷 2091-2152页

作者： jun Liu Dachun yang Mingdong Zhang School of Mathematics China University of Mining and TechnologyXuzhou 221116China Laboratory of Mathematics and Complex Systems(Ministry of Education of China) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875China

Let a:=(a_(1),...,a_(n))2[1,∞)^(n),p∈(0,1),andα:=1/*** any x∈R^(n)and t∈[0,∞),letΦ_(p)(x,t):={t/1+(t[x]_(a)^(ν))^(1-p)if να■N,t/1+(t[x]_(a)^(ν))^(1-p)[log(e+|x|a)]^(p)if να∈N,let where [·]a:=1+|·|a,|·|a denotes the anisotropic quasi-homogeneous norm with respect to a,and ν:=a_(1)+…+a_(n).Let H_(a)^(p)(R^(n)),L_(a)^(a)(R^(n)),and H_(a)^(Φ_(p))(R^(n))be,respectively,the anisotropic Hardy space,the anisotropic Campanato space,and the anisotropic Musielak-Orlicz Hardy space associated with Φ_(p) on R^(n).In this article,via first establishing the wavelet characterization of anisotropic Campanato spaces,we prove that for any f∈H_(a)^(p)(R^(n))and g∈L_(a)^(a)(R^(n)),the product of f and g can be decomposed into S(f,g)+T(f,g) in the sense of tempered distributions,where S is a bilinear operator bounded from H_(a)^(p)(R^(n))*L_(a)^(a)(R^(Φ_(p))) to L^(1)(R^(n)) and T is a bilinear operator bounded from H_(a)^(p)(R^(n))*L_(a)^(a)(R^(n)) to H_(a)^(Φ_(p))(R^(n)) .Moreover,this bilinear decomposition is sharp in the dual sense that any y■H_(a)^(Φ_(p))(R^(n)) that fits into the above bilinear decomposition should satisfy(L^(1)(R^(n))+y)*=(L^(1)(R^(n)+H_(a)^(Φ_(p))(R^(n))*.As applications,for any non-constant b∈L_(a)^(a)(R^(n)) and any sublinear operator T satisfying some mild bounded assumptions,we find the largest subspace of H_(a)^(p)(R^(n)),denoted by H_(a,b)^(p)(R^(n)),such that the commutator [b,T] is bounded from H_(a,b)^(p)(R^(n))to L^(1)(R^(n)).In addition,when T is an anisotropic CalderónZygmund operator,the boundedness of [b,T] from H_(a,b)^(p)(R^(n))to L^(1)(R^(n))(or to H_(a)^(1)(R^(n)) is also *** key of their proofs is the wavelet characterization of function spaces under consideration.

关键词： anisotropic Euclidean space bilinear decomposition Hardy space Campanato space Musielak-Orlicz Hardy space commutator wavelet

Unraveling the role of iron on Ni-Fe alloy nanoparticles during the electrocatalytic ethanol-to-acetate process

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Nano Research 2024年第4期17卷 2328-2336页

作者： junshan Li Luming Li Xinyu Ma jun Wang jun Zhao yu Zhang Ren He yaoyue yang Andreu Cabot yongfa Zhu Institute for Advanced Study Chengdu University610106 ChengduChina State Key Laboratory of Environmental-Friendly Energy Materials Southwest University of Science and TechnologyMianyang 621010China College of Food and Biological Engineering Chengdu UniversityChengdu 610106China School of Chemistry and Environment Southwest Minzu UniversityChengdu 610041China Hebei Key Laboratory of Photoelectric Control on Surface and Interface College of ScienceHebei University of Science and TechnologyShijiazhuang 050018China Catalonia Institute for Energy Research-IREC Sant Adriàde BesòsBarcelona 08930CataloniaSpain ICREA Pg.Lluís Companys 23Barcelona 08010CataloniaSpain Department of Chemistry Tsinghua UniversityBeijing 100084China

The anodic electrooxidation of ethanol to value-added acetate is an excellent example of replacing the oxygen evolution reaction to promote the cathodic hydrogen evolution reaction and save ***,we present a colloidal strategy to produce Ni-Fe bimetallic alloy nanoparticles(NPs)as efficient electrocatalysts for the electrooxidation of ethanol in alkaline ***-Fe alloy NPs deliver a current density of 100 mA·cm^(-2) in a 1.0 M KOH solution containing 1.0 M ethanol merely at 1.5 V *** hydrogen electrode(RHE),well above the performance of other electrocatalysts in a similar *** continuous 10 h testing at this external potential,this electrode is able to produce an average of 0.49 mmol·cm^(-2)·h^(-1) of acetate with an ethanol-to-acetate Faradaic efficiency of 80%.A series of spectroscopy techniques are used to probe the electrocatalytic process and analyze the ***,density functional theory(DFT)calculations demonstrate that the iron in the alloy NPs significantly enhances the electroconductivity and electron transfer,shifts the rate-limiting step,and lowers the energy barrier during the ethanol-to-acetate reaction pathway.

关键词： electrocatalysis ethanol oxidation reaction alloy nanoparticle acetate biorefinery

Engineering phonon thermal transport in few-layer PdSe_(2)

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Frontiers of physics 2024年第3期19卷 135-141页

作者： Meilin Li Huanhuan Sun jun Zhou yunshan Zhao Phonon Engineering Research Center of Jiangsu Province Center for Quantum Transport and Thermal Energy ScienceInstitute of Physics Frontiers and Interdisciplinary SciencesSchool of Physics and TechnologyNanjing Normal UniversityNanjing 210023China

Engineering phonon transport in low-dimensional materials has great significance not only for fundamental research,but also for thermal management applications of electric ***,due to the difficulties of micro and nano processing and characterization techniques,the work on tuning phonon transport at nanoscale are *** this work,by introducing Ar+plasma,we probed the phonon transport in two-dimensional(2D)layered semiconductor PdSe_(2)under different defect *** using thermal bridge method,the thermal conductivity was measured to decrease by 50%after a certain Ar+irradiation,which implied a possible phase ***,Raman characterizations were performed to show that the Raman sensitive peaks of PdSe_(2)was red-shifted and finally became disappeared with the increase of defect concentration.“Defect engineering”proves be a practical strategy in tuning the phonon thermal transport in low-dimensional materials,thus providing guidance for potential application in designing thermoelectric devices with various emerging materials.

关键词： phonon transport PdSe_(2) defects thermal bridge method

Microbiome and intestinal pathophysiology in post-acute sequelae of COVID-19

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Genes & Diseases 2024年第3期11卷 220-231页

作者： Jilei Zhang yongguo Zhang yinglin Xia jun Sun Division of Gastroenterology and Hepatology Department of MedicineUniversity of Ilinois ChicagoIL60612USA Uic Cancer Center Department of Microbiology and ImmunologyUniversity of Ilinois ChicagoChicagoIL60612USA Jesse Brown VA Medical Center ChicagoIL60612USA

Long CoVID,also known for post-acute sequelae of CovID-19,describes the people who have the signs and symptoms that continue or develop after the acute coviD-19 *** CovID patients suffer from an inflammation or host responses towards the virus approx-imately 4 weeks after initial infection with the SARS CoV-2 virus and continue for an unchar-acterized *** infected with CovID-19 before could experience long-CcovID conditions,including the patients who were infected with SARS CoV-2 virus confirmed by tests and those who never knew they had an infection *** with long CoviD may experience health problems from different types and combinations of symptoms over time,such as fa-tigue,dyspnea,cognitive impairments,and gastrointestinal(Gl)symptoms(e.g.,nausea,vom-iting,diarrhea,decreased or loss of appetite,abdominal pain,and dysgeusia).The critical role of the microbiome in these Gl symptoms and long CovID were reported in clinical patients and experimental ***,we provide an overall view of the critical role of the Gl tract and microbiome in the development of long COVID,including the clinical Gl symptoms in patients,dysbiosis,viral-microbiome interactions,barrier function,and inflammatory bowel disease patients with long *** highlight the potential mechanisms and possible treatment based on Gl health and ***,we discuss challenges and future direction in the long CoVID clinic and research.

关键词： Gastrointestinal symptoms Gl tract Gut microbiome Inflammatorybowel diseases Intestinal barrier Long CoVID Metabolites Tight junctions