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Two-fluid modeling of Geldart A particles in gas-fluidized beds

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Particuology 2008年第6期6卷 540-548页

作者： m.A. van der Hoef J.A.m. Kuipers Faculty of Science & Technology University of Twente

We have investigated the effect of cohesion and drag models on the bed hydrodynamics of Geldart A particles based on the two-fluid （TF） model. For a high gas velocity U0 = 0.03 m/s, we found a transition from the homogeneous fluidization to bubbling fluidization with an increase of the coefficient C1, which is used to account for the contribution of cohesion to the excess compressibility. Thus cohesion can play a role in the bed expansion of Geldart A particles. Apart from cohesion, we have also investigated the influence of the drag models. When using the Wen and Yu drag correlation with an exponent n = 4.65, we find an under-prediction of the bed expansion at low gas velocities （U0 = 0.009 m/s）. When using a larger exponent （n = 9.6）, as reported in experimental studies of gas-fluidization, a much better agreement with the experimental bed expansion is obtained. These findings suggest that at low gas velocity, a scale-down of the commonly used drag model is required. On the other hand, a scale-up of the commonly used drag model is necessary at high gas velocity （U0 = 0.2 and 0.06 m/s）. We therefore conclude that scaling the drag force represent only an ad hoc way of repairing the deficiencies of the TF model, and that a far more detailed study is required into the origin of the failure of the TF model for simulating fluidized beds of fine powders.

关键词： Gas-fluidized bed Geldart A particles Two-fluid model Cohesive force Drag correlation

Suboptimal Auditory Dominance in Audiovisual Integration of Temporal Cues

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Tsinghua Science and Technology 2011年第2期16卷 121-132页

作者： m maiworm B Rder Biological Psychology and Neuropsychology University of Hamburg

The present study examined whether audiovisual integration of temporal stimulus features in humans can be predicted by the maximum likelihood estimation （mLE） model which is based on the weighting of unisensory cues by their relative reliabilities. In an audiovisual temporal order judgment paradigm, the reliability of the auditory signal was manipulated by Gaussian volume envelopes, introducing varying degrees of temporal uncertainty. While statistically optimal weighting according to the mLE rule was found in half of the participants, the other half consistently overweighted the auditory signal. The results are discussed in terms of a general auditory bias in time perception, interindividual differences, as well as in terms of the conditions and limits of statistically optimal multisensory integration.

关键词： audiovisual integration statistically optimal behavior temporal perception

Neurogenesis dynamics in the olfactory bulb:deciphering circuitry organization, function, and adaptive plasticity

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Neural Regeneration Research 2025年第6期20卷 1565-1581页

作者： moawiah m.Naffaa Department of Psychology and Neuroscience Duke UniversityDurhamNCUSA Department of Cell Biology Duke University School of MedicineDurhamNCUSA

Adult neurogenesis persists after birth in the subventricular zone, with new neurons migrating to the granule cell layer and glomerular layers of the olfactory bulb, where they integrate into existing circuitry as inhibitory interneurons. The generation of these new neurons in the olfactory bulb supports both structural and functional plasticity, aiding in circuit remodeling triggered by memory and learning processes. However, the presence of these neurons, coupled with the cellular diversity within the olfactory bulb, presents an ongoing challenge in understanding its network organization and function. moreover,the continuous integration of new neurons in the olfactory bulb plays a pivotal role in regulating olfactory information processing. This adaptive process responds to changes in epithelial composition and contributes to the formation of olfactory memories by modulating cellular connectivity within the olfactory bulb and interacting intricately with higher-order brain regions. The role of adult neurogenesis in olfactory bulb functions remains a topic of debate. Nevertheless, the functionality of the olfactory bulb is intricately linked to the organization of granule cells around mitral and tufted cells. This organizational pattern significantly impacts output, network behavior, and synaptic plasticity, which are crucial for olfactory perception and memory. Additionally, this organization is further shaped by axon terminals originating from cortical and subcortical regions. Despite the crucial role of olfactory bulb in brain functions and behaviors related to olfaction, these complex and highly interconnected processes have not been comprehensively studied as a whole. Therefore, this manuscript aims to discuss our current understanding and explore how neural plasticity and olfactory neurogenesis contribute to enhancing the adaptability of the olfactory system. These mechanisms are thought to support olfactory learning and memory, potentially through increased

关键词： network adaptability neurogenesis neuronal communication olfactory bulb olfactory learning olfactory memory synaptic plasticity

mitochondria–cGAS–STING axis is a potential therapeutic target for senescence-dependent inflammaging-associated neurodegeneration

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Neural Regeneration Research 2025年第3期20卷 805-807页

作者： Josém.Izquierdo Centro de Biología molecular Severo Ochoa(CBm) Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid(CSIC-UAM)MadridSpain

The word “senescence” comes from the Latin senescens, meaning “to begin to age”, and is characterized by a long-lasting but reversible block in proliferation, resulting from stress-induced cell cycle arrest of pre... 详细信息

关键词： Latin potential lasting

Brain-penetrating neurotrophic factor mimetics: HER-096 as a disease-modifying therapy for Parkinson’s disease

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Neural Regeneration Research 2025年第4期20卷 1094-1095页

作者： Natalia Kulesskaya Kira m.Holmström Henri J.Huttunen Herantis Pharma Plc EspooFinland

Neurotrophic factors as a therapeutic approach in neurodegenerative diseases:A major unmet need in the field of central nervous system diseases is disease-modifying *** for decades there have been various symptomatic treatments available to alleviate the symptoms of the disease,disease-modification,*** that stop,significantly delay,or reverse the progression of the disease,has been turned out to a difficult goal to achieve.

关键词： diseases treatment therapeutic

Search for microglia-specific peptides:advances in the discovery toolbox

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Neural Regeneration Research 2025年第2期20卷 471-472页

作者： Ivan Sarabia Kyle m.Koss Department of Surgery University of ArizonaTucsonAZUSA

Uncontrolled and chronic inflammatory states in the central nervous system(CNS)are the hallmark of neurodegenerative pathology and every injury or stroke-related *** key mediators of these neuroinflammatory states are glial cells known as microglia,the resident immune cell at the core of the inflammatory event,and astroglia,which encapsulate inflammatory insults in proteoglycan-rich scar *** gliotic scar blocks significant portions of healthy axonal networking,preventing *** most neuroinflammation is exclusively based on the responses of said microglia,their phenotypes are suggested to follow those of macrophages;m1 and m2 are opposites of pro-and ***,microglial phenotypes have been identified to be on an inflammatory spectrum encompassing developmental,homeostatic,and reparative behaviors as opposed to their ability to affect devastating cell death cascades and scar tissue formation.

关键词： inflammation pathology death

Application of shortened heat treatment cycles on A356 automotive brake calipers with respective globular and dendritic microstructures

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Transactions of Nonferrous metals Society of China 2010年第9期20卷 1780-1785页

作者： H.mLLER G.GOVEN der W.E.STUmPF materials Science and manufacturing Council for Scientific and Industrial Research (CSIR) Department of materials Science and metallurgic al Engineering University of Pretoria

Since the automotive industry has many possible applications for semi-solid metal (SSm)-high-pressure die casting (HPDC) parts, the newly developed heat treatment cycles, as well as the traditional heat treatment cycles, were applied to A356 brake calipers cast using a LK DCC630 HPDC *** hardness measurements at a cross section of the brake calipers were performed, indicating that similar values can be obtained when using the significantly shorter heat treatment ***, the typical tensile properties that can be obtained for SSm-HPDC A356 brake calipers are compared with those manufactured by gravity die *** indicate that the differences in microstructures (globular or dendritic) do not have a noteworthy effect on the heat treatment *** implies that the short heat treatment cycles originally developed for globular SSm-HPDC A356 castings can be successfully applied to dendritic liquid A356 castings too.

关键词： semi-solid metal (SSm) forming heat treatment A356 brake caliper gravity die casting automotive

Biomimetic Sensors:Active Electrolocation of Weakly Electric Fish as a model for Active Sensing in Technical Systems

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Journal of Bionic Engineering 2007年第2期4卷 85-90页

作者： Gerhard von der Emde Zoological Institute University of Bonn53115 BonnGermany

Instead of vision, many nocturnal animals use alternative senses for navigation and object detection in their dark environment. For this purpose, weakly electric mormyrid fish employ active electrolocation, during which they discharge a specialized electric organ in their tail which discharges electrical pulses. Each discharge builds up an electrical field around the fish, which is sensed by cutaneous electroreceptor organs that are distributed over most of the body surface of the fish. Nearby objects distort this electrical field and cause a local alteration in current flow in those electroreceptors that are closest to the object. By constandy monitoring responses of its electroreceptor organs, a fish can detect, localize, and identify environmental objects. Inspired by the remarkable capabilities of weakly electric fish in detecting and recognizing objects, we designed technical sensor systems that can solve similar problems of remote object sensing. We applied the principles of active electrolocation to technical systems by building devices that produce electrical current pulses in a conducting medium （water or ionized gases） and simultaneously sense local current density. Depending on the specific task a sensor was designed for devices could （i） detect an object, （ii） localize it in space, （iii） determine its distance, and （iv） measure properties such as material properties, thickness, or material faults. Our systems proved to be relatively insensitive to environmental disturbances such as heat, pressure, or turbidity. They have a wide range of applications including material identification, quality control, non-contact distance measurements, medical applications and many more. Despite their astonishing capacities, our sensors still lag far behind what electric fish are able to achieve during active electrolocation. The understanding of the neural principles governing electric fish sensory physiology and the corresponding optimization of our sensors to solve

关键词： biomimetic weakly electric fish sensory system electrolocation sensor

Skin tribology:Science friction?

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Friction 2013年第2期1卷 130-142页

作者： E.VAN der HEIDE X.ZENG m.A.mASEN Laboratory for Surface Technology and Tribology Faculty of Engineering TechnologyUniversity of TwenteDrienerlolaan 57522 NB EnschedeThe Netherlands TNO De Rondom 15612 AP EindhovenThe Netherlands

The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering *** fact,effective solutions to friction and wear related questions can be found in our everyday *** important part is related to skin tribology,as the human skin is frequently one of the interacting surfaces in relative *** seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for *** question of course rises whether or not a trained tribologist would make different choices based upon a science based strategy?In other words:Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction?This paper discusses the specific nature of tribological systems that include the human skin and argues that the living nature of skin limits the use of conventional *** tribology requires in vivo,subject and anatomical location specific test *** predictive friction models can only partially be applied to predict in vivo skin *** reason for this is found in limited understanding of the contact mechanics at the asperity level of product-skin interactions.A recently developed model gives the building blocks for enhanced understanding of friction at the micro *** largely simplified power law based equations are currently available as general engineering ***,the need for friction control is illustrated by elaborating on the role of skin friction on discomfort and *** texturing and polymer brush coatings are promising directions as they provide way and means to tailor friction in sliding contacts without the need of major changes to the product.

关键词： friction bio-tribology skin soft tissue surface texture brush coatings