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CCAST“颗粒物理”研讨会

作者： M.Stein Y.L.ding j.P.K.Seville d.j.parker School of Chemical Engineering. University of Birmingham. Edgbaston. Birmingham B15 2TT. UK School of Chemical Engineering. University of Birmingham. Edgbaston Birmingham B15 2TT. UK Positron Imaging Centre University of Birmingham. Edgbaston Birmingham B15 2TT. UK School of Chemical Engineering. University of Birmingham. Edgbaston Birmingham B15 2TT. UK Positron Imaging Centre University of Birmingham. Edgbaston Birmingham B15 2TT. UK Positron Imaging Centre University of Birmingham. Edgbaston. Birmingham B15 2TT. UK School of Physics. University of Birmingham Edgbaston. Birmingham B15 2TT. UK

＜正＞ Gas fluidised beds are widely employed in the chemical, petrochemical, metallurgical, and pharmaceutical industries. Solids mixing in such devices plays a central role in controlling product quality and productivity. This paper presents some observations of particle motion in 3-d gas fluidised beds operated in the bubbling mode and at atmospheric pressure. The non-invasive positron emission particle tracking（PEPT） technique was used to observe and quantify particle trajectory, solids How pattern,solids velocity, and solids circulation frequency. It is shown that for relatively-deep beds （cylindrical columns, group B particles）, particles move upward in the central region, and downward near the wall. The average upward particle velocity is - 50% of the bubble velocity under the conditions of this study. Theoretical models are proposed to correlate the overall particle upward velocity and average particle velocity in the drift to the bubble velocity, and to estimate the duration of particle residence in the drift. Model predictions show reasonable agreement with experiments. It is suggested that solids motion in gas fluidised beds can be characterised by ’jump’, ’idle’ and ’relaxation’ times. These times may also be linked to particle kinetic energy transfer in lluidised beds. 2000 Elsevier Science Ltd. All rights reserved.

关键词： Gas fluidised bed Bubbling bed Solids motion Particle velocity Mixing PEPT

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Solids motion in rolling mode rotating drums operated at low to medium rotational speeds

Solids motion in rolling mode rotating drums operated at low...

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CCAST“颗粒物理”研讨会

作者： Y.L.ding j.P.K.Seville R.Forster d.j.parker School of Chemical Engineering . Positron Imaging Centre University of Birntingham Edgbaston Birmingham B15 2TT. UK School of Chemical Engineering . Positron Imaging Centre University of Birntingham Edgbaston Birmingham B15 2TT. UK School of Physics and Astronomy. Positron Imaging Centre. University of Birmingham. Edgbaston Birmingham B15 2TT UK School of Physics and Astronomy. Positron Imaging Centre. University of Birmingham. Edgbaston Birmingham B15 2TT UK

＜正＞ The industrial-scale rotating drums are usually operated in the rolling or slumping mode. For the rolling mode, the granular material bed can be divided into two regions, namely, a ’passive’ region where particles are carried up by the drum wall, and an ’active’ region where particles cascade down. As solids mixing mainly occurs in the active region, solids motion in this region and solids exchange between the active and passive regions are of prime importance for the overall performance of the drum. This paper reports some observations on particle motion in the transverse plane of a three-dimensional rotating drum operated at low and medium rotational speeds. The non-invasive PEPT （positron emission particle tracking） technique is used to follow particle trajectory and velocity. A mathematical model based on the thin-layer approximation is proposed to describe solids motion in the active layer. Reasonable agreement between the model predictions and experiments is obtained. A new parameter termed the ’solids exchange coefficient is proposed to characterise particle exchange between the passive and active regions. A theoretical expression for this parameter is also derived. This expression, upon application of the thin-layer approximation, is reduced to give an explicit relationship between the solids exchange coefficient and drum operating parameters such as rotational speed and fill percentage. as well as the bed material rheological properties. The solids exchange coefficient is also shown to give a possible scale-up rule for rotating drums operated in a rolling mode, 2001 Elsevier Science Ltd. All rights reserved.

关键词： Solids motion Solids mixing Rotating drums Rolling mode PEPT

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Granular motion in rotating drums: bed turnover time and slumping-rolling transition

Granular motion in rotating drums: bed turnover time and slu...

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CCAST“颗粒物理”研讨会

作者： Y.L.ding R.Forster j.P.K.Seville d.j.parker School of Chemical Engineering. University of Birmingham Edgbaston. Birmingham B15 2TT. UK Positron Imaging Centre. University of Birmingham Edgbaston. Birmingham B15 2TT UK Positron Imaging Centre. University of Birmingham. Edgbaston. Birmingham B15 2TT. UK School of Physics and Astronomy University of Birmingham. Edgbuston. Birmingham B15 2TT. UK School of Chemical Engineering. University of Birmingham Edgbaston. Birmingham B15 2TT. UK Positron Imaging Centre. University of Birmingham. Edgbaston. Birmingham B15 2TT. UK Positron Imaging Centre. University of Birmingham. Edgbaston. Birmingham B15 2TT. UK School of Physics and Astronomy University of Birmingham. Edgbuston Birmingham B15 2TT. UK

＜正＞ Theoretical models are presented tor calculation of the bed turnover time in both the slumping and rolling modes and the slumping-to-rolling transition in rotating drums with less than 50% volumetric fill of free-flowing granular materials. It is suggested that the transition from slumping to rolling occurs when the two turnover times arc equal. The model for the bed turnover time in rolling beds is compared with the data reported in the literature. Very good agreement has been obtained. The bed turnover time is also employed to define a new Froude number for constructing the bed behaviour *** is shown that the bed behaviour diagram based on the new Froude number brings the data points for sand and limestone into single curves. The implications of the bed turnover time for solid mixing and heat transfer within particle beds are also discussed. 2002 Elsevier Science B.V. All rights reserved.

关键词： Rotating drums Bed turnover time Solids motion Rolling mode Slumping mode Transition Bed behaviour diagram

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Segregation of granular flow in the transverse plane of a rolling mode rotating drum

Segregation of granular flow in the transverse plane of a ro...

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CCAST“颗粒物理”研讨会

作者： Y.L.ding R.Forster j.P.K.Seville d.j.parker School of Chemical Engineering. University of Birmingham Edgbaston. Birmingham B15 2TT UK Positron Imaging Centre. University of Birmingham. Edgbaston Birmingham B15 2TT. UK School of Physics and Astronomy University of Birmingham. Edghaston. Birmingham B15 2TT UK Positron Imaging Centre. University of Birmingham Edgbuston. Birmingham B15 2TT. UK School of Chemical Engineering. University of Birmingham. Edgbaston. Birmingham B15 2TT UK Positron Imaging Centre University oj Birmingham Edgbaston Birmingham B15 2TT. UK School of Physics and Astronomy University of Birmingham. Eagbaston. Birmingham B15 2TT UK Positron Imaging Centre. University of Birmingham. Edgbaston. Birmingham B15 2TT. UK

＜正＞ This paper reports some observations on the behaviour of a segregated particle bed consisting of a mixture of small and large particles in the transverse plane of a rolling mode rotating drum. A non-invasive positron emission particle tracking （PERT） technique was used to follow the trajectories of different sized particles. A two-dimensional mathematical model based on the Eulerian approach and the thin layer approximation was developed to simulate solids motion and concentration distribution of different sized particles. It is shown that the bed structure for a binary mixture is similar to that for mono-sized particles, i.e. two-region structure consisting of a relatively thin ’active’ region and a ’passive’ region near the drum wall where particles move as a rigid body. At low rotational speeds, the velocity difference between small and large particles of a binary system is negligible in both the active and passive regions. At relatively high rotational speeds, the velocity difference is small in the active region and negligible in the passive region. Radial occupancy data suggest that small particles tend to concentrate in the core region, whereas large particles tend to occupy the shell region, in good agreement with model predictions. Axial occupancy data reveal that the axial particle mobility increases with drum rotational speed, and the mutual diffusivity of small particles is higher than that of large particles. It is also shown that the turnover time ratio of small to large particles is almost independent of concentrations of small particles under the conditions of this work. 2002 Elsevier Science Ltd. All rights reserved.

关键词： Particle segregation Solids motion Rotating drum Rolling mode Bed turnover time Mathematical modelling PEPT

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Scaling relationships for rotating drums

Scaling relationships for rotating drums

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CCAST“颗粒物理”研讨会

作者： Y.L.ding R.N.Forster j.P.K.Seville d.j.parker School of Chemical Engineering. University of Birmingham Edgbastoh Birmingham B15 2TT. UK School of Physics and Astronomy University of Birmingham.Edgbaston Birmingham B15 2TT. UK School of Chemical Engineering University of Birmingham EdgbastonBirmingham B15 2TT. UK School of Physics and Astronomy University of Birmingham. Edgbaston Birmingham B15 2TT. UK

Rotating drums are extensively used in the chemical and process industries as kilns, mixers, dryers and reactors. despite challenges from the development of newer and more specialised technologies such as fluidised beds, rotating drums continue to find applications. This is mainly due to their ability to handle varying feed stock’s, in particular granular materials with broad particle size distribution and significant difference in physical properties. However, the scale-up methodology tor such devices is still largely empirical and no general and systematic method has been established. This work is therefore devoted to the development of a set of scaling relationships which can be used to properly design rotating drums. The sealing relationships are obtained by non-dimensionalising the differential equations governing the behaviour of solids motion in rotating drums. The derived dimensionless groups include Froude number, pseudo-Reynolds number, pseudo-Euler number, drum geometric ratios, drum inclination, drum fill percentage, size distribution of particles, and physical properties of the particles and drum wall such as restitution coefficient and elasticity modulus. At relatively low pseudo-Reynolds numbers, the effect of velocity fluctuation and hence the granular temperature can be neglected, the granular Hows are thus in the quasi-static regime. At relatively low pscudo-Euler numbers, the effect of the frictional contribution to the total stress tensor is negligible and the flow is in the rapid granular flow regime. The upper limit of the quasi-static regime is evaluated and the adequacy of the application of granular flow kinetic theory to rotating drums is discussed. It is shown that granular flows in large drums operated at low to medium rotational speeds are often in Ihe quasi-static regime, whereas those in small drums operated at medium relational speeds may be in the transition How regime. Preliminary experiments have been carried out with the aim of re

关键词： Rotating drum Scaling relationships Solids mixing Granular flow Rolling mode

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Treating amyotrophic lateral sclerosis with allogeneic Schwann cell-derived exosomal vesicles: a case report

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Neural Regeneration Research 2025年第4期20卷 1207-1216页

作者： Pascal j.Goldschmidt-Clermont Aisha Khan George jimsheleishvili Patricia Graham Adriana Brooks Risset Silvera Alexander j.P.Goldschmidt damien d.Pearse W.dalton dietrich Allan d.Levi james d.Guest Miller School of Medicine University of MiamiMiamiFLUSA Stem Cell Institute Miller School of MedicineUniversity of MiamiMiamiFLUSA The Miami Project to Cure Paralysis Miller School of MedicineUniversity of MiamiMiamiFLUSA Alzady International LLC MiamiFLUSA Neurological Surgery Miller School of MedicineUniversity of MiamiMiamiFLUSA

Schwann cells are essential for the maintenance and function of motor neurons,axonal networks,and the neuromuscular *** amyotrophic lateral sclerosis,where motor neuron function is progressively lost,Schwann cell function may also be ***,important signaling and potential trophic activities of Schwann cell-derived exosomal vesicles have been *** case report describes the treatment of a patient with advanced amyotrophic lateral sclerosis using serial intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles,marking,to our knowledge,the first instance of such *** 81-year-old male patient presented with a 1.5-year history of rapidly progressive amyotrophic lateral *** initial diagnosis,the patient underwent a combination of generic riluzole,sodium phenylbutyrate for the treatment of amyotrophic lateral sclerosis,and *** patient volunteered to participate in an FdA-approved single-patient expanded access treatment and received weekly intravenous infusions of allogeneic Schwann cell-derived exosomal vesicles to potentially restore impaired Schwann cell and motor neuron *** confirmed that cultured Schwann cells obtained from the amyotrophic lateral sclerosis patient via sural nerve biopsy appeared impaired(senescent)and that exposure of the patient’s Schwann cells to allogeneic Schwann cell-derived exosomal vesicles,cultured expanded from a cadaver donor improved their growth capacity in *** a period of observation lasting 10 weeks,during which amyotrophic lateral sclerosis Functional Rating Scale-Revised and pulmonary function were regularly monitored,the patient received weekly consecutive infusions of 1.54×1012(×2),and then consecutive infusions of 7.5×1012(×6)allogeneic Schwann cell-derived exosomal vesicles diluted in 40 mL of dulbecco’s phosphate-buffered *** of the infusions were associated with adverse events such as infusion reactions(allergic or otherwise)or

关键词： allogeneic amyotrophic lateral sclerosis exosomes infusion neuromuscular junction Schwann cell

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维普期刊数据库

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Positron emission particle tracking——Application and labelling techniques

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Particuology 2008年第1期6卷 16-23页

作者： david j. parker School of Physics and Astronomy the University of Birmingham Edgbaston Birmingham B15 2TT UK

The positron emission particle tracking （PEPT） technique has been widely used in science and engineering to obtain detailed information on the motion and flow fields of fluids or granular materials in multiphase systems, for example, fluids in rock cracks, chemical reactors and food processors; dynamic behaviour of granular materials in chemical reactors, granulators, mixers, dryers, rotating kilns and ball mills. The information obtained by the PEPT technique can be used to optimise the design, operational conditions for a wide range of industrial process systems, and to evaluate modelling work. The technique is based on tracking radioactively labelled particles （up to three particles） by detecting the pairs of backto-back 511 keV γ-rays arising from annihilation of emitted positrons. It therefore involves a positron camera, location algorithms for calculating the tracer location and speed, and tracer labelling techniques. This paper will review the particle tracking technique from tracking algorithm, tracer labelling to their application.

关键词： PEPT Tracer Algorithm Tracking

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维普期刊数据库

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Apples to oranges:environmentally derived,dynamic regulation of serotonin neuron subpopulations in adulthood?

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Neural Regeneration Research 2025年第9期20卷 2596-2597页

作者： Christopher j.O’Connell Matthew j.Robson department of Genetics College of MedicineHarvard UniversityBostonMAUSA james L.Winkle College of Pharmacy Division of Pharmaceutical SciencesUniversity of CincinnatiCincinnatiOHUSA Neuroscience Graduate Program College of MedicineUniversity of CincinnatiCincinnatiOHUSA

Traumatic brain injury(TBI)is a public health problem with an undue economic burden that impacts nearly every age,ethnic,and gender group across the globe(Capizzi et al.,2020).TBIs are often sustained during a dynamic range of exposures to energetic environmental forces and as such outcomes are typically heterogeneous regarding severity and pathology(Capizzi et al.,2020).

关键词： sustained orange dynamic

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维普期刊数据库

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The ethical cost of doing nothing

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National Science Review 2020年第7期7卷 1260-1262页

作者： Andrew j.parker University of Oxford Department of PhysiologyAnatomy and Genetics

Concern has been raised about the ethics and risks of performing genetic interventions in macaque monkeys to study models of human neuropsychiatric conditions. Here I point out that,when the outcome of some situations is truly uncertain, human decision makers tend to evaluate these situations inconsistently. The consequences of this inconsistency are sometimes profound, as they lead policy makers and reviewers to ignore or discount the ethical costs of doing nothing. I conclude that there are fundamental problems with the ‘precautionary

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Gene therapy for spinal muscular atrophy:perspectives on the possibility of optimizing SMN1 delivery to correct all neurological and systemic perturbations

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Neural Regeneration Research 2025年第7期20卷 2011-2012页

作者： Sharon j.Brown Rafael j.Yáñez-Muñoz Heidi R.Fuller School of Pharmacy and Bioengineering Keele UniversityKeeleUK Wolfson Center for Inherited Neuromuscular disease TORCH BuildingRJAH Orthopaedic HospitalOswestryUK *** Center of Gene and Cell TherapyDepartment of Biological SciencesSchool of Life Sciences and the EnvironmentRoyal Holloway University of LondonEghamUK

Spinal muscular atrophy(SMA)is a genetic condition that results in selective lower motor neuron loss with concomitant muscle weakness and *** genetic cause of SMA was understood in 1995 when loss or impairment of the survival motor neuron 1(SMN1)gene was identified as the main contributing factor(Lefebvre et al.,1995).This,in combination with the discovery that humans have a“back-up”gene,SMN2,which can produce low levels(approximately 10%)of the full-length functional SMN protein,has led to the generation of SMA-specific gene *** was traditionally classified according to age of symptom onset and developmental milestones achieved,with life expectancy and severity varying between ***,SMN2 copy number is used as a proxy for the prediction of disease severity,with higher SMN2 copy number typically being associated with reduced severity of SMA,although this relationship is not absolute:some individuals with low SMN2 copy number have less severe SMA phenotypes and vice ***,the etiology of SMA is further complicated by other factors,such as non-typical nucleotide variants and SMN2-independent modifiers of disease severity.

关键词： atrophy traditionally absolute

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