scholarly journals Development of a Droplet Microfluidics Device Based on Integrated Soft Magnets and Fluidic Capacitor for Passive Extraction and Redispersion of Functionalized Magnetic Particles

2020 ◽  
Vol 5 (4) ◽  
pp. 1901088 ◽  
Author(s):  
Marco Serra ◽  
Emilie Gontran ◽  
Ismail Hajji ◽  
Laurent Malaquin ◽  
Jean‐Louis Viovy ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Droplet Microfluidics ◽  
Soft Magnets

A Numerical Study on Separation Characteristics of Magnetic Particles in Magnetophoretic Chip Microchannels

2009 ◽  
Author(s):  
Xinyu Wu ◽  
Huiying Wu
Keyword(s):  
Dynamic Characteristics ◽  
Magnetic Particles ◽  
Numerical Study ◽  
Fluid Velocity ◽  
Capture Efficiency ◽  
Low Flow ◽  
Flow Rates ◽  
Soft Magnets ◽  
Design And Optimization ◽  
Capture Time

In this paper, a two-dimensional dynamic model describing the separation behaviors of magnetic particles in magnetophoretic chip microchannels integrated with double-side symmetric and asymmetric soft magnets is proposed and solved with the combining use of the finite element method and the fourth-order Runge-Kutta method. The dynamic characteristics of magnetic particles during the separation process, including the trajectories of magnetic particles, the capture time and capture efficiency are analyzed. The impacts of the geometrical configurations, fluid velocity and magnetic field intensity are also studied. The results show that the trajectories of the magnetic particles in microchannels are oscillatory because of the alternative magnetic force and this oscillation is more obvious for asymmetric positions of the soft magnets. The oscillatory motion of the particle leads to the increase of the moving distance and delay of the capture time. The capture time depends on the geometrical configurations, the initial positions and the dynamic characteristics of the particles. It is also found that under the same strength of magnetic fields there is nearly no difference on the capture efficiency for symmetric and asymmetric configurations. With the increase of fluid velocity, the capture efficiency drops drastically at low flow rates and decreases slowly at high flow rates. The distance between soft magnets and microchannel walls has the similar influence on capture efficiency. It is expected that the results presented in this paper are helpful for the design and optimization of magnetophoretic separation microsystems.

A magnetic super lattice

1987 ◽  
Vol 45 ◽  
pp. 360-361 ◽  
Author(s):  
M.D. Bentzon ◽  
J. v. Wonterghem ◽  
A. Thölén
Keyword(s):  
Thermal Decomposition ◽  
Oleic Acid ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Carbon Film ◽  
Thick Layer ◽  
Amorphous Iron ◽  
Super Lattice ◽  
Carrier Liquid ◽  
Median Diameter

We report on the oxidation of a magnetic fluid. The oxidation results in magnetic super lattice crystals. The “atoms” are hematite (α-Fe2O3) particles with a diameter ø = 6.9 nm and they are covered with a 1-2 nm thick layer of surfactant molecules.Magnetic fluids are homogeneous suspensions of small magnetic particles in a carrier liquid. To prevent agglomeration, the particles are coated with surfactant molecules. The magnetic fluid studied in this work was produced by thermal decomposition of Fe(CO)5 in Declin (carrier liquid) in the presence of oleic acid (surfactant). The magnetic particles consist of an amorphous iron-carbon alloy. For TEM investigation a droplet of the fluid was added to benzine and a carbon film on a copper net was immersed. When exposed to air the sample starts burning. The oxidation and electron irradiation transform the magnetic particles into hematite (α-Fe2O3) particles with a median diameter ø = 6.9 nm.

EFFECT OF APPLICATION OF FIELDS ON THE DOMAIN STRUCTURE IN SMALL REGULARLY SHAPED MAGNETIC PARTICLES

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-1817-C8-1818 ◽  
Author(s):  
S. McVitie ◽  
J. N. Chapman ◽  
S. J. Hefferman ◽  
W. A. P. Nicholson
Keyword(s):  
Domain Structure ◽  
Magnetic Particles

Analysis of magneto rheological elastomers for energy harvesting systems

2020 ◽  
Vol 64 (1-4) ◽  
pp. 439-446
Author(s):  
Gildas Diguet ◽  
Gael Sebald ◽  
Masami Nakano ◽  
Mickaël Lallart ◽  
Jean-Yves Cavaillé
Keyword(s):  
Magnetic Field ◽  
Energy Harvesting ◽  
Shear Strain ◽  
Magnetic Induction ◽  
Magnetic Particles ◽  
Homogeneous Magnetic Field ◽  
Electrical Signal ◽  
Harvesting Systems ◽  
Dc Bias ◽  
Magneto Rheological

Magneto Rheological Elastomers (MREs) are composite materials based on an elastomer filled by magnetic particles. Anisotropic MRE can be easily manufactured by curing the material under homogeneous magnetic field which creates column of particles. The magnetic and elastic properties are actually coupled making these MREs suitable for energy conversion. From these remarkable properties, an energy harvesting device is considered through the application of a DC bias magnetic induction on two MREs as a metal piece is applying an AC shear strain on them. Such strain therefore changes the permeabilities of the elastomers, hence generating an AC magnetic induction which can be converted into AC electrical signal with the help of a coil. The device is simulated with a Finite Element Method software to examine the effect of the MRE parameters, the DC bias magnetic induction and applied shear strain (amplitude and frequency) on the resulting electrical signal.

Tuning the Magnetic Vortex State in Magnetite Nanodiscs for Remote Control of Biological Signalling

2019 ◽  
Author(s):  
Danijela Gregurec ◽  
Alexander W. Senko ◽  
Andrey Chuvilin ◽  
Pooja Reddy ◽  
Ashwin Sankararaman ◽  
...  
Keyword(s):  
Remote Control ◽  
Ion Channels ◽  
Ground State ◽  
Magnetic Particles ◽  
Colloidal Stability ◽  
Vortex State ◽  
Magnetic Vortex ◽  
Electron Holography ◽  
Dipole Interactions ◽  
Magnetite Particles

In this work, we demonstrate the application of anisotropic magnetite nanodiscs (MNDs) as transducers of torque to mechanosensory cells under weak, slowly varying magnetic fields (MFs). These MNDs possess a ground state vortex configuration of magnetic spins which affords greater colloidal stability due to eliminated dipole-dipole interactions characteristic of isotropic magnetic particles of similar size. We first predict vortex magnetization using micromagnetic stimulations in sub-micron anisotropic magnetite particles and then use electron holography to experimentally investigate the magnetization of MNDs 98–226 nm in diameter. When MNDs are coupled to MFs, they transition between vortex and in-plane magnetization allowing for the exertion of the torque on the pN scale, which is sufficient to activate mechanosensitive ion channels in cell membranes.<br>

Preparation and Properties of Arrays of Very Small Magnetic Particles.

1987 ◽  
Author(s):  
C. D. Graham ◽  
Kaatz Jr. ◽  
Forrest
Keyword(s):  
Magnetic Particles

scholarly journals Geochemical and Mineralogical Characteristics of Airborne Particulate Matter in Relation to Human Health Risk

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 866 ◽  
Author(s):  
Marzena Rachwał ◽  
Małgorzata Wawer ◽  
Mariola Jabłońska ◽  
Wioletta Rogula-Kozłowska ◽  
Patrycja Rogula-Kopiec
Keyword(s):  
Magnetic Susceptibility ◽  
Particulate Matter ◽  
Human Health ◽  
Magnetic Particles ◽  
Rank Order ◽  
Human Health Risk ◽  
Airborne Particulate Matter ◽  
Ambient Air ◽  
Average Concentration ◽  
Health Indices

The main objective of this research was the determination of the geochemical and mineralogical properties of particulate matter: TSP (total suspended particles) and, especially PM1 (particles with aerodynamic diameter not greater than 1 µm) suspended in the air of a selected urban area in southern Poland. Identification of the emission sources of metals and metalloids bound in TSP and PM1 as well as the assessment of potential risk of urban ambient air to human health using hazard indices was an additional aim of this investigation. The daily TSP and PM1 quartz fiber filters collected during heating season were subjected to mass magnetic susceptibility (χ) measurements, SEM (Scanning Electron Microscopy) observations and geochemical analyses. Obtained results revealed that the concentration of TSP and PM1 well correlated with their mass-specific magnetic susceptibility. The good relationship between the PM concentration and χ suggests that magnetic susceptibility measurements can be a good proxy of low-level atmospheric dust pollution. The rank order of potentially toxic elements (PTE) based on average concentration was Ba > Zn > Al > Fe > Pb > Mn > Ti > Cu > Cr > Ni >As > Cd > V > Tl, both for TSP and PM1. PM1/TSP ratios for PTE concentrations and χ were around or slightly above unity, which indicated that PM1 was the main carrier of PTE (with the exception of cadmium, copper and lead) and technogenic magnetic particles. The non-carcinogenic and carcinogenic risks were confirmed by very high values of human health indices.

scholarly journals How to Improve Physico-Chemical Properties of Silk Fibroin Materials for Biomedical Applications?—Blending and Cross-Linking of Silk Fibroin—A Review

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1510
Author(s):  
Sylwia Grabska-Zielińska ◽  
Alina Sionkowska
Keyword(s):  
Silk Fibroin ◽  
Biomedical Applications ◽  
Magnetic Particles ◽  
Chemical Properties ◽  
Ternary Mixtures ◽  
Cross Linking ◽  
Advantages And Disadvantages ◽  
Physico Chemical ◽  
Binary And Ternary Mixtures ◽  
To Receive

This review supplies a report on fresh advances in the field of silk fibroin (SF) biopolymer and its blends with biopolymers as new biomaterials. The review also includes a subsection about silk fibroin mixtures with synthetic polymers. Silk fibroin is commonly used to receive biomaterials. However, the materials based on pure polymer present low mechanical parameters, and high enzymatic degradation rate. These properties can be problematic for tissue engineering applications. An increased interest in two- and three-component mixtures and chemically cross-linked materials has been observed due to their improved physico-chemical properties. These materials can be attractive and desirable for both academic, and, industrial attention because they expose improvements in properties required in the biomedical field. The structure, forms, methods of preparation, and some physico-chemical properties of silk fibroin are discussed in this review. Detailed examples are also given from scientific reports and practical experiments. The most common biopolymers: collagen (Coll), chitosan (CTS), alginate (AL), and hyaluronic acid (HA) are discussed as components of silk fibroin-based mixtures. Examples of binary and ternary mixtures, composites with the addition of magnetic particles, hydroxyapatite or titanium dioxide are also included and given. Additionally, the advantages and disadvantages of chemical, physical, and enzymatic cross-linking were demonstrated.

scholarly journals Specific and rapid reverse assaying protocol for detection and antimicrobial susceptibility testing of Pseudomonas aeruginosa based on dual molecular recognition

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yong He ◽  
Hang Zhao ◽  
Yuanwen Liu ◽  
He Zhou
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Susceptibility ◽  
Magnetic Particles ◽  
Susceptibility Testing ◽  
Fluorescein Isothiocyanate ◽  
High Specificity ◽  
Antimicrobial Susceptibility Testing ◽  
Tail Fiber ◽  
Isolation And Identification ◽  
Magainin Ii

AbstractThe worldwide emergence and spread of antimicrobial resistance is accelerated by irrational administration and use of empiric antibiotics. A key point to the crisis is a lack of rapid diagnostic protocols for antimicrobial susceptibility testing (AST), which is crucial for a timely and rational antibiotic prescription. Here, a recombinant bacteriophage tail fiber protein (TFP) was functionalized on magnetic particles to specifically capture Pseudomonas aeruginosa, while fluorescein isothiocyanate-labeled-magainin II was utilized as the indicator. For solving the magnetic particles’ blocking effects, a reverse assaying protocol based on TFP recognition was developed to investigate the feasibility of detection and AST of P. aeruginosa. P. aeruginosa can be rapidly, sensitively and specifically detected within 1.5 h with a linear range of 1.0 × 102 to 1.0 × 106 colony forming units (CFU)⋅mL−1 and a detection limit of 3.3 × 10 CFU⋅mL−1. Subsequently, AST results, which were consistent with broth dilution results, can be obtained within 3.5 h. Due to the high specificity of the TFP, AST can actually be conducted without the need for bacterial isolation and identification. Based on the proof-of-principle work, the detection and AST of other pathogens can be extended by expressing the TFPs of their bacteriophages.

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