scholarly journals Rheotaxis and migration of an unsteady microswimmer

2021 ◽  
Vol 930 ◽  
Author(s):  
T. Omori ◽  
K. Kikuchi ◽  
M. Schmitz ◽  
M. Pavlovic ◽  
C.-H. Chuang ◽  
...  
Keyword(s):  
Flow Field ◽  
Boundary Element ◽  
Channel Flow ◽  
Swimming Velocity ◽  
The Novel ◽  
Simple Analytical Model ◽  
Physical Origin ◽  
Physical Mechanisms ◽  
And Migration ◽  
Migration Of Cells

Rheotaxis and migration of cells in a flow field have been investigated intensively owing to their importance in biology, physiology and engineering. In this study, first, we report our experiments showing that the microalgae Chlamydomonas can orient against the channel flow and migrate to the channel centre. Second, by performing boundary element simulations, we demonstrate that the mechanism of the observed rheotaxis and migration has a physical origin. Last, using a simple analytical model, we reveal the novel physical mechanisms of rheotaxis and migration, specifically the interplay between cyclic body deformation and cyclic swimming velocity in the channel flow. The discovered mechanism can be as important as phototaxis and gravitaxis, and likely plays a role in the movement of other natural microswimmers and artificial microrobots with non-reciprocal body deformation.

Preparation and Characterization of Porous Material from Self-Organized Hydroxyapatite/Collagen Nanocomposite

2005 ◽  
Vol 873 ◽  
Author(s):  
Shunji Yunoki ◽  
Toshiyuk Ikoma ◽  
Akira Monkawa ◽  
Masanori Kikuchi ◽  
Junzo Tanaka
Keyword(s):  
The Novel ◽  
Filling Materials ◽  
Sodium Phosphate Buffer ◽  
Self Organized ◽  
And Migration ◽  
Early Regeneration ◽  
Porous Composites ◽  
Regeneration Of Bone ◽  
Migration Of Cells

AbstractSelf-organized hydroxyapatite /collagen (HAp/Col) nanocomposite was synthesized by a co-precipitated method. The porous HAp/Col nanocomposites with unidirectional and interconnected pores with approximately 20μm in size were prepared by a facile method. The ice crystals were grown up at a cooling brass bottom in the paste which kneaded the HAp/Col nanocomposite with a sodium phosphate buffer. The freeze-drying technique produced the replica of ice structures, and the porous composites showed the anisotropic compressive strengths. The nanostructure and micropore structure are of great importance for developing the novel artificial bone filling materials; attachment and migration of cells and blood vessels, and early regeneration of bone tissues.

Fundamental Issues and Recent Advancements in Analysis of Aircraft Brake Natural Convective Cooling

1998 ◽  
Vol 120 (4) ◽  
pp. 840-857 ◽  
Author(s):  
M. P. Dyko ◽  
K. Vafai
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Flow Field ◽  
Three Dimensional ◽  
Convective Cooling ◽  
Cooling Flow ◽  
Physical Mechanisms ◽  
Braking System ◽  
Flow And Heat Transfer ◽  
Convection Cooling

A heightened awareness of the importance of natural convective cooling as a driving factor in design and thermal management of aircraft braking systems has emerged in recent years. As a result, increased attention is being devoted to understanding the buoyancy-driven flow and heat transfer occurring within the complex air passageways formed by the wheel and brake components, including the interaction of the internal and external flow fields. Through application of contemporary computational methods in conjunction with thorough experimentation, robust numerical simulations of these three-dimensional processes have been developed and validated. This has provided insight into the fundamental physical mechanisms underlying the flow and yielded the tools necessary for efficient optimization of the cooling process to improve overall thermal performance. In the present work, a brief overview of aircraft brake thermal considerations and formulation of the convection cooling problem are provided. This is followed by a review of studies of natural convection within closed and open-ended annuli and the closely related investigation of inboard and outboard subdomains of the braking system. Relevant studies of natural convection in open rectangular cavities are also discussed. Both experimental and numerical results obtained to date are addressed, with emphasis given to the characteristics of the flow field and the effects of changes in geometric parameters on flow and heat transfer. Findings of a concurrent numerical and experimental investigation of natural convection within the wheel and brake assembly are presented. These results provide, for the first time, a description of the three-dimensional aircraft braking system cooling flow field.

Abstract 15691: The Novel High Mobility Group Protein Hmgxb4 Promotes Neointimal Formation in Response to Arterial Injury

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
xiangqin he ◽  
Kunzhe Dong ◽  
Jian Shen ◽  
Islam Osman ◽  
Guoqing Hu ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Neointimal Hyperplasia ◽  
Critical Role ◽  
High Mobility ◽  
Arterial Injury ◽  
The Novel ◽  
Neointimal Formation ◽  
Vsmc Proliferation ◽  
And Migration

Introduction: Restenosis after percutaneous intervention is predominantly attributed to proliferation and migration of vascular smooth muscle cells (VSMCs). However, the key regulators responsible for VSMC proliferation and migration remain to be identified. Hypothesis: We previously reported that the novel high mobility group (HMG) nuclear protein HMGXB4 (HMG-Box containing 4) plays a critical role in the de-differentiation of vascular smooth muscle cells in vitro and in acute inflammatory response to septic shock. We hypothesize that HMGXB4 is critical for neointimal hyperplasia in response to inflammatory stimuli. Methods and Results: We found that the expression of HMGXB4 is dramatically induced in ligation or wire injury-induced neointimal hyperplasia and correlated with the activation of inflammatory signaling in mice. Using an inducible smooth muscle-specific Hmgxb4 KO (knockout) mice model, we found specific KO of Hmgxb4 in VSMCs ameliorates ligation- or wire- injury induced neointimal formation. Among an array of growth factors and inflammation cytokines, we found that TNFα and INFγ effectively induces the expression of HMGXB4 in VSMCs and correlates with the VSMC proliferation in vitro. Furthermore, we found deletion of HMGXB4 attenuates while over-expression of HMGXB4 promotes inflammation cytokines-induced VSMC proliferation in vitro. These results suggest injury-induced inflammatory signal triggers HMGXB4 induction, which, in turn, promotes the VSMC proliferation and neointimal formation. Conclusions: Our study not only demonstrates a critical role of HMGXB4 in promoting neointimal hyperplasia in response the arterial injury, but also suggests HMGXB4 is a potential novel target for the management of restenosis in human.

Michael Winterbottom’s The Claim (2000) as a transnational and transcultural adaptation of The Mayor of Casterbridge

2021 ◽  
Vol 14 (2) ◽  
pp. 195-207 ◽  
Author(s):  
Margarida Esteves Pereira
Keyword(s):  
Thomas Hardy ◽  
Film Adaptation ◽  
Cultural Dimension ◽  
Clear Understanding ◽  
The Novel ◽  
Community Construction ◽  
Transcultural Adaptation ◽  
Film Productions ◽  
And Migration ◽  
Transnational Film

In this article, we will be focusing on issues of transnational and transcultural film adaptation using as a case study a particular screen adaptation of the novel The Mayor of Casterbridge by Thomas Hardy entitled The Claim (Michael Winterbottom 2000). The article aims to analyse the film in relation to these issues, taking into account notions of transcultural adaptation and transnational film productions, as well as mobility and migration in the context of a nineteenth-century film text. It is not only a text that relocates Hardy’s narrative into a new geographical/cultural dimension, but also it is itself a transnational production. Moreover, in the case of The Claim, there seems to be a clear understanding of processes of intercultural community construction that are particularly productive to look at. The article establishes a link between the particular transcultural perspective raised in this film and Michael Winterbottom’s oeuvre, taking also into account other adaptations of Hardy’s novels by the same director and the Western genre that underlies this film production.

scholarly journals Large eddy simulation of turbulent channel flow using differential equation wall model

2018 ◽  
Vol 15 (2) ◽  
pp. 75-89
Author(s):  
Muhammad Saiful Islam Mallik ◽  
Md. Ashraf Uddin
Keyword(s):  
Differential Equation ◽  
Flow Field ◽  
Channel Flow ◽  
Turbulent Channel Flow ◽  
Wall Region ◽  
Computational Domain ◽  
Wall Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Near Wall

A large eddy simulation (LES) of a plane turbulent channel flow is performed at a Reynolds number Re? = 590 based on the channel half width, ? and wall shear velocity, u? by approximating the near wall region using differential equation wall model (DEWM). The simulation is performed in a computational domain of 2?? x 2? x ??. The computational domain is discretized by staggered grid system with 32 x 30 x 32 grid points. In this domain the governing equations of LES are discretized spatially by second order finite difference formulation, and for temporal discretization the third order low-storage Runge-Kutta method is used. Essential turbulence statistics of the computed flow field based on this LES approach are calculated and compared with the available Direct Numerical Simulation (DNS) and LES data where no wall model was used. Comparing the results throughout the calculation domain we have found that the LES results based on DEWM show closer agreement with the DNS data, especially at the near wall region. That is, the LES approach based on DEWM can capture the effects of near wall structures more accurately. Flow structures in the computed flow field in the 3D turbulent channel have also been discussed and compared with LES data using no wall model.

scholarly journals miR-615 Fine-Tunes Growth and Development and Has a Role in Cancer and in Neural Repair

Cells ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1566 ◽  
Author(s):  
Marisol Godínez-Rubí ◽  
Daniel Ortuño-Sahagún
Keyword(s):  
Growth And Development ◽  
Target Genes ◽  
Noncoding Rnas ◽  
Tumor Promoter ◽  
Neural Repair ◽  
Small Noncoding Rnas ◽  
Physiological Processes ◽  
And Migration ◽  
Migration Of Cells ◽  
Regulation Of Growth

MicroRNAs (miRNAs) are small noncoding RNAs that function as epigenetic modulators regulating almost any gene expression. Similarly, other noncoding RNAs, as well as epigenetic modifications, can regulate miRNAs. This reciprocal interaction forms a miRNA-epigenetic feedback loop, the deregulation of which affects physiological processes and contributes to a great diversity of diseases. In the present review, we focus on miR-615, a miRNA highly conserved across eutherian mammals. It is involved not only during embryogenesis in the regulation of growth and development, for instance during osteogenesis and angiogenesis, but also in the regulation of cell growth and the proliferation and migration of cells, acting as a tumor suppressor or tumor promoter. It therefore serves as a biomarker for several types of cancer, and recently has also been found to be involved in reparative processes and neural repair. In addition, we present the pleiad of functions in which miR-615 is involved, as well as their multiple target genes and the multiple regulatory molecules involved in its own expression. We do this by introducing in a comprehensible way the reported knowledge of their actions and interactions and proposing an integral view of its regulatory mechanisms.

scholarly journals Evaluation of Preosteoblast MC3T3-E1 Cells Cultured on a Microporous Titanium Membrane Fabricated Using a Precise Mechanical Punching Process

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5288
Author(s):  
Jingyu Zhang ◽  
Yukihiko Sakisaka ◽  
Hiroshi Ishihata ◽  
Kentaro Maruyama ◽  
Eiji Nemoto ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Limited Information ◽  
Expression Levels ◽  
Promote Cell Proliferation ◽  
Proliferation And Differentiation ◽  
Punching Process ◽  
And Migration ◽  
Titanium Membrane ◽  
Migration Of Cells ◽  
Gene Expression Levels

The surface topography of Titanium (Ti) combined toughness and biocompatibility affects the attachment and migration of cells. Limited information of morphological characteristics, formed by precise machining in micron order, is currently available on the Ti that could promote osteoconduction. In the present study, a pure Ti membrane was pierced with precise 25 μm square holes at 75 μm intervals and appear burrs at the edge of aperture. We defined the surface without burrs as the “Head side” and that with burrs as the “Tail side”. The effects of the machining microtopography on the proliferation and differentiation of the preosteoblasts (MC3T3-E1 cells) were investigated. The cells were more likely to migrate to, and accumulate in, the aperture of holes on the head side, but grew uniformly regardless of holes on the tail side. The topography on the both surfaces increased osteopontin gene expression levels. Osteocalcin expression levels were higher on the head side than one on the blank scaffold and tail side (p < 0.05). The osteocalcin protein expression levels were higher on the tail side than on the head side after 21 days of cultivation, and were comparable to the proportion of the calcified area (p < 0.05). These results demonstrate the capacity of a novel microporous Ti membrane fabricated using a precise mechanical punching process to promote cell proliferation and activity.

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