scholarly journals Synthesis and properties of magnetic microspheres based on magnetite and hydrophilic polymers

2020 ◽  
Vol 56 (2) ◽  
pp. 135-142
Author(s):  
K. V. Laznev ◽  
Ye. Y. Shumskaya ◽  
V. Y. Agabekov
Keyword(s):  
Polyvinyl Alcohol ◽  
Room Temperature ◽  
Immunomagnetic Separation ◽  
Residual Magnetization ◽  
Hydrophilic Polymers ◽  
Magnetic Microspheres ◽  
Buffer Solution ◽  
Magnetite Particles

Using emulsification technique, magnetic microspheres (MMS) were prepared from solutions of alginate, pectin, gelatin, chitosan and polyvinyl alcohol. Index of polidispersity of the microspheres was ≤ 0.1. The microspheres from gelatin, chitosan and polyvinyl alcohol covalently crosslinked with glutaraldehyde were resistant to sonication and hydrolysis at room temperature in buffer solution with pH   7.4. The microspheres containing superparamagnetic magnetite particles demonstrated no residual magnetization. After modification, chitosan and polyvinyl alcohol MMS were used for immunomagnetic separation of cells and germs.

A New Method for Direct Determination of the Recoilless Fraction with Application to Magnetic Nanoparticles

2002 ◽  
Vol 721 ◽  
Author(s):  
Monica Sorescu
Keyword(s):  
Room Temperature ◽  
Average Particle Size ◽  
Direct Determination ◽  
Average Particle ◽  
Lattice Method ◽  
Recoilless Fraction ◽  
Single Room ◽  
Magnetite Particles ◽  
Physical Mixtures

AbstractWe propose a two-lattice method for direct determination of the recoilless fraction using a single room-temperature transmission Mössbauer measurement. The method is first demonstrated for the case of iron and metallic glass two-foil system and is next generalized for the case of physical mixtures of two powders. We further apply this method to determine the recoilless fraction of hematite and magnetite particles. Finally, we provide direct measurement of the recoilless fraction in nanohematite and nanomagnetite with an average particle size of 19 nm.

Magnetic Enhancement and Nitriding Process of Fe Atomic Layers on Si (111)-7×7-CH3OH Surface

2021 ◽  
Author(s):  
Wenxin Li ◽  
Wanyu Ding ◽  
Youping Gong ◽  
Dongying Ju
Keyword(s):  
Formation Mechanism ◽  
Room Temperature ◽  
Adsorption Process ◽  
Linear Structure ◽  
Atomic Layer ◽  
Residual Magnetization ◽  
Good Stability ◽  
Iron Nitride ◽  
Dissociation Process ◽  
Magnetic Performance

Abstract Fe atoms were steamed on Si(111)-7×7 surface, which had been saturated by CH3OH. Aim to greatly enhance the magnetic performance, nitriding experiments were implemented and adjusted on the existing linear Fe clusters. First of all, the dissociation of CH3OH adsorption process was deducted in detail, which laid a good foundation for the better use of surface quasi-potential. Further to solve the coming problems like weak linearity and low nitriding effect, the formation mechanism of iron-nitride was explored. Atomic layers of Fe deposition are confirmed as the key to NH3 dissociation process (at room temperature). Specifically, the higher Fe atomic layer contacted by NH3, the weaker influence of surface quasi-potential. With the introduction of Ar, Fe deposition could be controlled at 1-2 atomic layers, result in good NH3 dissociation and nitriding efficiency. Combing with magnetic performance result, the density of residual magnetization is improved from 1.5E-0.5 emu to 7.0E-0.5 emu, forming an obvious linear structure. It is also proved that our new linear iron-nitride clusters will maintain good stability with the improvement of nitriding efficiency.PACS: 07.79.Cz; 81.15.-z; 75.75.Fk

Gas Chromatographic/Mass Spectrometric Determination of Erythromycin in Beef and Pork

1987 ◽  
Vol 70 (4) ◽  
pp. 708-713
Author(s):  
Keigo Takatsuki ◽  
Shigeru Suzuki ◽  
Nobutoshi Sato ◽  
Isamu Ushizawa ◽  
Takuro Shoji
Keyword(s):  
Room Temperature ◽  
Phosphate Buffer Solution ◽  
Mass Spectrometric ◽  
Buffer Solution ◽  
Residual Level ◽  
Electron Impact Mass ◽  
Full Scan ◽  
Impact Mass ◽  
Chromatographic Mass

Abstract A gas chromatographic/mass spectrometric (GC/MS) method is described for the determination of residual erythromycin in beef and pork. This method allows detection and quantitation of residual erythromycin in beef and pork by using single-ion monitoring; confirmation by a full scan electron impact mass spectrum is possible if residual level in a sample is ≥ 1 ppm. Erythromycin is extracted with methanol from a sample and cleaned up by n-hexane washing followed by partition between chloroform and phosphate buffer solution. The cleaned up extract is chromatographed on a silica gel column, acid hydrolyzed, and acetylated in acetic anhydride-pyridine mixture (1 + 2) at room temperature. The reaction mixture is injected into the GC/MS apparatus, and detection and quantitation are conducted using single-ion monitoring at m/z 200. The recoveries (CV, %) at 1 and 0.1 ppm fortification levels are 86% (2.7%) and 72% (7.7%), and the detection limit is 0.01 ppm.

Effect of interface on temperature dependent magnetoresistance and room temperature magnetoimpedance of La0.7Sr0.3MnO3/Polyvinyl Alcohol nanocomposites

2020 ◽  
Vol 582 ◽  
pp. 411962
Author(s):  
Debajit Deb ◽  
Rajesh Debnath ◽  
S.K. Mandal ◽  
Archana Lakhani ◽  
A. Nath ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Room Temperature ◽  
Temperature Dependent

Synthesis, Characterization and In Vitro Drug Release of Melphalan Magnetic Microspheres

2013 ◽  
Vol 22 ◽  
pp. 31-40
Author(s):  
Jin Qiao Xu ◽  
Hai Xing Xu ◽  
Zubad Newaz ◽  
Ran Li ◽  
Yu Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Drug Release ◽  
Drug Loading ◽  
Phosphate Buffer Solution ◽  
Magnetic Microspheres ◽  
Targeted Chemotherapy ◽  
Buffer Solution ◽  
Magnetization Measurements ◽  
Co Precipitation

A new method of reversible association of melphalan (MEL) to magnetic Fe3O4 nanoparticles preparing MEL magnetic microspheres was developed for magnetically targeted chemotherapy. The efficacy of this approach was evaluated in terms of encapsulation efficiency (EE), drug loading content (DLC), delivery properties and cytotoxicity in vitro. Magnetic Fe3O4 nanoparticles were synthesized by co-precipitation methods and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and magnetization measurements. The MEL magnetic microspheres were obtained through emulsion cross-linking method and characterized by FTIR, magnetization measurements and scan electron microscopy (SEM). The EE and DLC were determined using a Spectro Vision DB-18805 spectrophotometer. The MEL magnetic microspheres showed good EE values, between 60.6% and 75.6%, as well as good DLC values, between 16.7% and 32.2%, and the magnetic properties were not significantly affected by incorporation of the drug. The in vitro drug release study was carried out in phosphate buffer solution (PBS), simulating physiologic body fluid conditions at 37o C with pH = 7.4. The release profiles showed an initial fast release rate, which decreased as time progressed; about 60% of the drug was released in the first 4 h, and about 78.23 % had been released after 24 h. The results indicated that the prepared magnetic microspheres may be useful for potential applications of MEL for magnetically targeted chemotherapy.

Rubber Elasticity and Gas Elasticity

1939 ◽  
Vol 12 (2) ◽  
pp. 124-129
Author(s):  
H. Mark
Keyword(s):  
Polyvinyl Alcohol ◽  
Room Temperature ◽  
Absolute Temperature ◽  
Rubber Elasticity ◽  
Chain Molecules ◽  
Internal Mobility ◽  
Higher Temperature ◽  
Coefficient Of Elasticity ◽  
Polyacrylic Ester ◽  
High Degree

Abstract All substances which are composed of long mobile chains show one peculiar property, highly reversible elasticity. Even though the range of temperature of this property may be notably variable (in the case of polyvinyl alcohol and rubber at about room temperature, in the case of polystyrene, sulfur, or Thiokol only at a higher temperature) still it is to be noted that for rubber-like elasticity the presence of long flexible chains is an indispensable factor. Thus, typical rubber elasticity occurs in polyvinyl alcohol (Vinarol), polybutadiene (Buna), polymethyl-butadiene (methyl rubber), polyacrylic ester and also in its mixed polymerisate with vinyl chloride. This type of elasticity occurs also in sinew fibrin and muscle fibrin, in polychlorobutadiene (Neoprene, Sovprene), in polyethylene sulfide (Thiokol, Baerite), polyphosphornitrile chloride and finally in vulcanized oils (factice) and also in elastic sulfur. In the cases so far examined (natural rubber, Buna, methyl rubber), it has been found that the coefficient of elasticity increases proportionally to the absolute temperature, and that during the stretching heat is evolved. This behavior is contrary to that of normal elastic materials, steel, quartz, glass, etc. It is striking that the substances which have this property of highly reversible (rubber-like) stretching are widely different chemically. This tempts one to ascribe that property to the similarity of their construction. For example, all the substances mentioned consist of long chain-molecules, which display a high degree of internal mobility. The number of members in these chains varies from 102 to 104 and their mobility is due to the kind of linkage between the members, mostly simple C—C bonds.

Effect of M-ZrO2 on Sintering Behavior and Thermal Shock Resistance of Dense Cr2O3 Material

2011 ◽  
Vol 199-200 ◽  
pp. 1928-1931 ◽  
Author(s):  
Hong Ji Yin ◽  
Tao Zhang ◽  
Ai Jun Wu ◽  
Jin Xiang Wang
Keyword(s):  
Polyvinyl Alcohol ◽  
Oxygen Partial Pressure ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
Cold Isostatic Pressing ◽  
Sintering Behavior ◽  
Quenching Effect ◽  
Material Sample ◽  
Shock Resistance

The samples were prepared using Cr2O3 micropowder, TiO2 micropowder and m-ZrO2 micropowder as main starting material, polyvinyl alcohol as binder, by a series of processes such as pulping, spraying granulation, machine moulding and cold isostatic pressing, and sintering at 1 500°С for 3 h in nitrogen protected atmosphere furnace (oxygen partial pressure was 10 Pa). Then thermal shock resistance of the samples was tested by wind quenching. Effect of m-ZrO2 (2%-5% in mass) on sintering behavior and thermal shock resistance of Cr2O3 material was investigated. The results show that m-ZrO2 can accelerate the sintering of Cr2O3 material, but excess 2 wt% m-ZrO2 doesn’t work; m-ZrO2 can obviously improve thermal shock resistance of Cr2O3 material, sample containing 3 wt% m-ZrO2 has 34 wind quenching cycles from 1 150°С to room temperature, and sample without m-ZrO2 only has 11 cycles.

Influence of Blocking Agents on Non-Specific Background of Polystyrene Microbeads in Serum Immunoassay

2013 ◽  
Vol 641-642 ◽  
pp. 858-861 ◽  
Author(s):  
Zhi Min Ren ◽  
Xi Nie ◽  
Sheng Shu Ai
Keyword(s):  
Bovine Serum Albumin ◽  
Polyvinyl Alcohol ◽  
Serum Albumin ◽  
Human Serum ◽  
Phosphate Buffer ◽  
Bovine Serum ◽  
Room Temperature ◽  
Tween 20 ◽  
Blocking Agents

In this paper, we used bovine serum albumin and polymer as the blocking agents and investigated the effect of blocking agents on non-specific background of polystyrene microbead that used the human serum immunoassay.The results showed that the nonspecific background is lower by using polymer blocking agents. The best blocking condition was that microbeads were blocked by PVXT (0.5% polyvinyl alcohol PVA, 0.8% polyvinylpyrrolidone, 0.05% Tween-20, PBS phosphate buffer, pH7.0) for two hours at room temperature.

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