Ions, adsorption and electric response of a ferrofluid cell

2022 ◽  
Author(s):  
Fernando Batalioto ◽  
Antonio Figueiredo Neto ◽  
Giovanni Barbero
Keyword(s):  
Magnetic Particles ◽  
Electric Response ◽  
A Cell

We show that the electric response of a cell in the shape of a slab containing a ferrofluids (magnetic particles in kerosene) can be interpreted by means of a model...

Improvement of the magneto-electric effect of composites loaded with different magnetic particles for current sensor applications

2019 ◽  
Vol 87 (1) ◽  
pp. 10901 ◽  
Author(s):  
Mahmoud El Mouden ◽  
Fouad Belhora ◽  
Yassine Tabbai ◽  
Abdelowahed Hajjaji ◽  
Abdessamad El Ballouti
Keyword(s):  
Magnetic Field ◽  
Magnetic Particles ◽  
Vinylidene Fluoride ◽  
Flexible Substrate ◽  
Composite Films ◽  
Excitation Frequency ◽  
Homogeneous Solution ◽  
Dimethyl Formamide ◽  
Electric Response ◽  
Electric Effect

This article proposes a methodology to improve the magneto-electric effect of a poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFe) copolymer, doped with nanoparticles of nickel (Ni) and nickel iron (NiFe). The preparation of the composite films were achieved through the solvent casting approach. First, P(VDF-TrFe) powders and (Ni and NiFe) nanoparticles are dispersed in dimethyl formamide (DMF) as a solvent to form a homogeneous solution. Then, the solution obtained is deposited on a flexible substrate by a spin coating process. After that, the NiFe doped composites are corona polarized, to improve the magneto-electric response of these composites. The purpose of this work is to investigate the influence of the magnetic charges added in the P(VDF-TrFe) copolymer, and to reveal the effect of corona charging (polarization) on the magneto-electric behavior of the used composites. The obtained results in this article show that both the doping and the electric polarization (piezo coefficient) significantly affect the generated alternating current during the application of an alternating magnetic field. However, the magneto-electric response of composites increases by doping and charging via corona poling effect and also by increasing the excitation frequency and the magnetic field amplitude. In addition, the magneto-electric responses of all composites after corona polarization were also discussed. This indicates that the magneto-electric coefficient and the current can be increased with polarized composites. A good response is observed for P(VDF-TrFe) + 3% Ni with a piezoelectric coefficient d33 = 21.2 (pC/N)

Response of an Osteoblast to Cyclic Strain at Its Focal Adhesions Using Magnetic Micropillars

2012 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Takuya Ohara ◽  
Shin Morishita ◽  
Ryohei Takeuchi
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Focal Adhesion ◽  
Mechanical Stimulation ◽  
Magnetic Particles ◽  
Focal Adhesions ◽  
Cyclic Strain ◽  
Osteoblast Cell ◽  
A Cell ◽  
The Difference

This paper describes a micro device which applies cyclic strain to focal adhesions of a cell. In recent years, evidence has been growing that focal adhesions act as mechanosensors of cells which convert mechanical force into biomechanical signaling. However, there are no effective micro devices which can directly apply mechanical stimulation to each focal adhesion. Here we develop a micropillar substrate embedding micron-sized magnetic particles and enabling the micropillars to be deflected by external magnetic field. The combination of long and short micropillars produces the difference of deflection between them and enables the micropillars to apply strain to a cell. The long pillars were periodically deflected at the amplitude of approximately 1.4 μm whereas most of short pillars were not deflected. Using the magnetic micropillar substrate, we observed the deformation of an osteoblast cell at its focal adhesions. The findings indicate that the present micro device can be used for investigating mechanosensing systems of a cell.

scholarly journals A method for time-resolved measurements of the mechanics of phagocytic cups

2013 ◽  
Vol 10 (82) ◽  
pp. 20121048 ◽  
Author(s):  
Matthias Irmscher ◽  
Arthur M. de Jong ◽  
Holger Kress ◽  
Menno W. J. Prins
Keyword(s):  
Tumour Growth ◽  
Magnetic Particles ◽  
Time Resolved ◽  
Actin Cortex ◽  
A Cell ◽  
Oscillating Magnetic Field ◽  
Phagocytic Cups ◽  
20 Nm ◽  
Pronounced Peak

The internalization of matter by phagocytosis is of key importance in the defence against bacterial pathogens and in the control of cancerous tumour growth. Despite the fact that phagocytosis is an inherently mechanical process, little is known about the forces and energies that a cell requires for internalization. Here, we use functionalized magnetic particles as phagocytic targets and track their motion while actuating them in an oscillating magnetic field, in order to measure the translational and rotational stiffnesses of the phagocytic cup as a function of time. The measured evolution of stiffness reveals a characteristic pattern with a pronounced peak preceding the finalization of uptake. The measured stiffness values and their time dependence can be interpreted with a model that describes the phagocytic cup as a prestressed membrane connected to an elastically deformable actin cortex. In the context of this model, the stiffness peak is a direct manifestation of a previously described mechanical bottleneck, and a comparison of model and data suggests that the membrane advances around the particle at a speed of about 20 nm s −1 . This approach is a novel way of measuring the progression of emerging phagocytic cups and their mechanical properties in situ and in real time.

A Method for Applying High Cyclic Strain to Focal Adhesions and Measuring the Cell Response

2013 ◽  
Author(s):  
Toshihiko Shiraishi ◽  
Takuya Ohara ◽  
Shin Morishita
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Focal Adhesion ◽  
High Frequency ◽  
Magnetic Particles ◽  
Focal Adhesions ◽  
Cyclic Strain ◽  
Osteoblast Cell ◽  
A Cell ◽  
The Difference

This paper describes a method by which broadband cyclic strain can be applied to focal adhesions of a cell. In recent years, evidence has been growing that focal adhesions act as mechanosensors of cells which convert mechanical force into biomechanical signaling. However, there are no effective methods by which mechanical stimulation with high frequency can be directly applied to each focal adhesion. Here we develop a micropillar substrate embedding micron-sized magnetic particles and enabling the micropillars to be deflected by external magnetic field. The combination of long and short micropillars produces the difference of deflection between them and enables the micropillars to apply strain to a cell. We verified that the micropillars responded to external magnetic field up to at least 25 Hz without phase difference. Using the magnetic micropillar substrate, we observed the cytoskeletal deformation of an osteoblast cell. The findings indicate that the present micro device can be used for investigating mechanosensing systems of a cell.

Electric response of a cell of hydrogel: Role of the electrodes

2011 ◽  
Vol 98 (6) ◽  
pp. 064101 ◽  
Author(s):  
A. L. Alexe-Ionescu ◽  
R. Atasiei ◽  
C. Dascalu ◽  
F. C. M. Freire ◽  
G. Barbero
Keyword(s):  
Electric Response ◽  
A Cell

Effect of Niacin on Mitochondria of Allium Cepa Root Cells

1967 ◽  
Vol 25 ◽  
pp. 78-79
Author(s):  
M. Arif Hayat
Keyword(s):  
Nicotinamide Adenine Dinucleotide ◽  
Hydrogen Transfer ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Nicotinamide Adenine ◽  
Root Tips ◽  
Root Cells ◽  
Transfer Processes ◽  
Standard Procedures ◽  
A Cell ◽  
Critical Interest

Although it is recognized that niacin (pyridine-3-carboxylic acid), incorporated as the amide in nicotinamide adenine dinucleotide (NAD) or in nicotinamide adenine dinucleotide phosphate (NADP), is a cofactor in hydrogen transfer in numerous enzyme reactions in all organisms studied, virtually no information is available on the effect of this vitamin on a cell at the submicroscopic level. Since mitochondria act as sites for many hydrogen transfer processes, the possible response of mitochondria to niacin treatment is, therefore, of critical interest.Onion bulbs were placed on vials filled with double distilled water in the dark at 25°C. After two days the bulbs and newly developed root system were transferred to vials containing 0.1% niacin. Root tips were collected at ¼, ½, 1, 2, 4, and 8 hr. intervals after treatment. The tissues were fixed in glutaraldehyde-OsO4 as well as in 2% KMnO4 according to standard procedures. In both cases, the tissues were dehydrated in an acetone series and embedded in Reynolds' lead citrate for 3-10 minutes.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

Dendritic cells of the human epidermis: immuno-electron microscopic studies of la antigen reactivity

1978 ◽  
Vol 36 (2) ◽  
pp. 644-645
Author(s):  
G. Rowden ◽  
M. G. Lewis ◽  
T. M. Phillips
Keyword(s):  
Dendritic Cells ◽  
Langerhans Cells ◽  
Cell Types ◽  
Cell Type ◽  
Electron Microscopic ◽  
La Antigen ◽  
Microscopic Studies ◽  
A Cell ◽  
C3 Receptors ◽  
Antigen Reactivity

Langerhans cells of mammalian stratified squamous epithelial have proven to be an enigma since their discovery in 1868. These dendritic suprabasal cells have been considered as related to melanocytes either as effete cells, or as post divisional products. Although grafting experiments seemed to demonstrate the independence of the cell types, much confusion still exists. The presence in the epidermis of a cell type with morphological features seemingly shared by melanocytes and Langerhans cells has been especially troublesome. This so called "indeterminate", or " -dendritic cell" lacks both Langerhans cells granules and melanosomes, yet it is clearly not a keratinocyte. Suggestions have been made that it is related to either Langerhans cells or melanocyte. Recent studies have unequivocally demonstrated that Langerhans cells are independent cells with immune function. They display Fc and C3 receptors on their surface as well as la (immune region associated) antigens.

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