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Far-infrared absorption studies of Be acceptors in δ-doped GaAs/AlAs multiple quantum wells

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Science China(physics,Mechanics & Astronomy) 2006年第6期49卷 702-708页

作者： M. p. Halsall p. Harrison M. j. Steer School of physics and Astronomy the University of ManchesterManchester M60 1QD U. K. School of Electronic and Electrical Engineering University of LeedsLS2 9JT U. K. EpSRC Ⅲ-V Semiconductor Central Facility Department of Electronic and Electrical Engineering University of SheffieldS1 3JD U. K.

We report a far-infrared absorption study of internal transitions of shallow Be acceptors in both bulk GaAs and a series of δ-doped GaAs/AlAs multiple quantum well samples with well thicknesses of 20,15 and 10 nm. Low temperature far-infrared absorp-tion measurements clearly show three principal absorption lines due to transitions of Be-acceptor states from the ground state to the first three odd-parity excited states,respec-tively. Using a variational principle,the 2p-1s transition energies of quantum confined Be acceptors are calculated as a function of the well width. It is found that the theoretical calculation of the 2pz → 1s transitions is in good agreement with the D-like line experi-mental data.

关键词： shallow acceptor impurities,δ-doped,GaAs/AlAs multiple quantum wells,far-infrared absorptions.

A new thermodynamically stable Nb_(2)Ni intermetallic compound phase revealed by peritectoid transition within binary Nb-Ni alloy system

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journal of Materials Science & Technology 2022年第5期100卷 246-253页

作者： j.F.Zhao H.p.Wang B.Wei School of physical Science and Technology Northwestern Polytechnical UniversityXi’an 710072China

A new intermetallic compound of thermodynamically stable Nb_(2)Ni phase is discovered within Nb-Ni binary system,refreshing the current situation that there are only three stable intermediate phases of Nb_(7)Ni_(6),NbNi_(3) and NbNi_(8).The new stable phase is generated from the peritectoid transition:(Nb)+Nb_(7)Ni_(6)→Nb_(2)Ni,and the transformation temperature is 1533 *** refreshes the current equilibrium Nb-Ni binary phase *** is confirmed by transmission electron microscopy and the annealing experiments,which is determined to be the FCC structure(pearson:cF96,space grope:Fd-3m O2,a=11.888A).Furthermore,the equilibrium properties of Nb_(2)Ni phase are produced by density functional theory,including the formation energy,cohesive energy,bulk modulus and lattice constant.

关键词： Intermetallic compound peritectoid transition Transmission electron microscopy Density functional theory Nb alloy

ON THE DESCRIpTION OF ANISOTROpIC DAMAGE IN COMpOSITE LAMINATES

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Acta Mechanica Sinica 1991年第4期7卷 335-343页

作者：杨卫 j.p.Boehler Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China Institut de Me’canique de Grenoble University Joseph FourierGrenoble I.38041 Grenoble CedexFrance

A general anisotropic damage theory of cracked laminates is formulated *** deformation of composite laminates is composed of matrix elastic strains,pseudo-elastic damage strains due to cracking and permanent damage strains due to interlaminar *** surface of damage initiation is constructed accord- ing to the concept of linear elastic fracture mechanics for the virgin *** the initial damage,a pesudo-elastic damage can be used to describe the damage behaviour if interlaminar slip is *** evolution,load induced anisotropy and interlaminar-intralaminar interaction for composite laminates are exam- ined;the latter can perturb the normality structure of damage strain *** expressions are given for pseudo-elastic (or secant) moduli of the damaging composite laminates,under a non-interacting assumption imposed on the cracks between different families.

关键词： composite laminates anisotropic damage constitutive modelling

Wettability,reactivity,and interface structure in Mg/Ni system

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journal of Magnesium and Alloys 2024年第2期12卷 659-672页

作者： S.Terlicka N.Sobczak Ł.Maj p.Darłak j.j.Sobczak Institute of Metallurgy and Materials Science Polish Academy of Sciences25 Reymonta Str.KrakowPoland Faculty of Foundry Engineering AGH University23 Reymonta Str.KrakowPoland

The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni *** comparison,the experiments were performed in two variants:(1)using the Capillary purification(Cp)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)*** high-temperature tests were performed under isothermal conditions(Cp:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) *** the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate *** and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified *** was found that an oxide-free Mg drop obtained by the Cp procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθpreading and good wetting over the Ni substrate(θ_((Cp))~20°in 5 s)to form a final contact angle ofθ_(f(Cp))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test ***,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.

关键词： Magnesium-based alloys Sessile drop tests Capillary purification procedure Wettability Reactivity Contact angle

Emerging role of A-kinase anchoring protein 5 signaling in reward circuit function

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Neural Regeneration Research 2025年第10期20卷 2913-2914页

作者： William j.Flerlage Mark L.Dell’Acqua Brian M.Cox Fereshteh S.Nugent Uniformed Services University of the Health Sciences Department of Pharmacology and Molecular TherapeuticsBethesdaMDUSA Department of pharmacology University of Colorado School of MedicineAnschutz Medical CampusAuroraCOUSA

There is a strong evidence supporting the hypothesis of synaptic dysfunction as a major contributor to neural circuit and network disruption underlying emotional and mood dysregulation in psychiatric disorders(Simmons et al.,2024).Diverse sets of distinct molecular signaling pathways converge on the synapse to regulate synaptogenesis,synaptic function,and synaptic plasticity in brain regions and circuits through complex interactions organized by numerous multivalent protein scaffolds,including the family of proteins known as A-kinase anchoring proteins(AKAps).

关键词： function supporting

Analysis of mesoscale effects in high-shear granulation through a computational fluid dynamics-population balance coupled compartment model

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particuology 2018年第1期16卷 1-12页

作者： p.j. Abrahamsson p. Kvist G. Reynolds X. Yu I. Niklasson Bjorn M.j. Hounslow A. Rasmuson Department of Chemical and Biological Engineering Chalmers University of Technology SE-412 96 Gothenburg Sweden pharmaceutical Development AstraZeneca Macclesfield SK10 2NA UK European Bioenergy Research Institute (EBRI) School of Engineering and Applied Science Aston University Birmingham B4 7ET UK AstraZeneca pharmaceutical and Analytical R&D Molndal SE-431 83 Moldnal Sweden Department of Chemical and Biological Engineering University of Sheffield Sheffield SI 3JD UK

There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes the high-shear granulation process based on relevant process parameters in time and space. The model comprises a coupled-flow-field and population-balance solver and is used to resolve and analyze the effects of mesoscales on the evolution of particle properties. A Diosna high-shear mixer was modelled with microcrystalline cellulose powder as the granulation material. An analysis of the flow-field solution and compartmentalization allows for a resolution of the stress and collision peak at the impeller blades. Different compartmentalizations showed the importance of resolving the impeller region, for aggregating systems and systems with breakage. An independent study investigated the time evolution of the flow field by changing the particle properties in three discrete steps that represent pow- der mixing, the initial granulation stage mixing and the late stage granular mixing. The results of the temporal resolution study show clear changes in collision behavior, especially from powder to granular mixing, which indicates the importance of resolving mesoscale phenomena in time and space.

关键词： High-shear wet granulation population-balance model Compartment model Computational fluid dynamics

Additive manufacturing of Sm-Fe-N magnets

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journal of Rare Earths 2019年第10期37卷 1078-1082页

作者： j.A.B.Engerroff A.B.Baldissera M.D.Magalhaes p.H.Lamarao p.A.p.Wendhausen C.H.Ahrens j.M.Mascheroni Department of Mechanical Engineering Federal University of Santa CatarinaFlorianopolisBrazil AlkimatTecnologia Sao JoseBrazil

Isotropic Sm-Fe-N bonded magnets were obtained by additive manufacturing(AM). The technique used was the so-called powder bed fusion(pBF) and the feedstock was composed of a polymeric binder(pA-12) and Sm-Fe-N flake particles(Nitroquench-p). The AM set-up equipment uses a computer-controlled CO2 laser beam to melt the binder and constructs magnets layer-by-layer. In order to develop this study, a cylinder with 10 mm of both height and diameter was selected as the shape of samples. Specimens were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Magnetic properties were measured in a hysteresis graph. XRD results indicate that there is no degradation of the main magnetic phase(SmFe7 Nx). In the AM component, porous regions were identified on SEM micrographs, as well as magnetic particles and polymeric binder. Remanence values(Br) as great as 0.3 T are achieved, while intrinsic coercivities remain in the range from 616 up to 642 kA/m. An additional isostatic compression of the parts results in greater remanence, which is directly proportional to the density increase. Coercivity is also sensitive to the porosity decrease, probably due to a better interlocking of particles. Current results indicate AM as a promising route for near net-shape manufacturing of Sm-Fe-N permanent magnets, a market niche yet to be widely explored.

关键词： Sm-Fe-N permanent magnets Additive manufacturing Rare earths

Tests of spaceborne rain radar retrieval algorithms by simulation

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Chinese Science Bulletin 1997年第5期42卷 402-405页

作者： j. Testud p. Amayenc Centre d' etudes des Environnements Terrestre et planetaires Issy-les-Moulineaux FranceCentre d' etudes des Environnements Terrestre et Planetaires Issy-les-Moulineaux France

THE rainfall rate is related statistically to the radar reflectivity, but the return power of

关键词： rainfall rate spaceborne rain radar algorithm.

Magnetohydrodynamic(MHD)boundary layer heat and mass transfer characteristics of nanofluid over a vertical cone under convective boundary condition

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propulsion and power Research 2018年第4期7卷 308-319页

作者： p.Sudarsana Reddy p.Sreedevi Ali j.Chamkha Department of Mathematics RGM College of Eng.&TechNandyal 518501APIndia Mechanical Engineering Department Prince Mohammad Bin Fahd University.Al-Khobar 31952Kingdom of Saudi Arabia

This paper investigates the boundary layer flow,heat and mass transfercharacteristics over a vertical cone filled with nanofluid saturated porous medium with theinfluence of magnetic field,thermal radiation and first order chemical reaction subject to theconvective boundary *** transformation technique is used for the purpose ofconverting non-linear partial differential equations into the system of complex ordinarydifferential *** computational Finite element method has been employed to solvethe flow,heat and mass transfer equations together with boundary *** impact ofvarious pertinent parameters on hydrodynamic,thermal and solutal boundary layers isinvestigated and the results are displayed ***,the values of local skin-friction coefficient,rate of temperature and rate of concentration is also calculated and theresults are presented *** comparisons with previously published work is made andfound good *** thickness of thermal boundary layer is increased with increase inthe values of Brownian motion parameter(Nb)and thermophoresis parameter(Ni).

关键词： Heat andmasstransfer Vertical cone Nanofluid Convective boundary condition Finite elementmethod Chemical reaction