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Search Results: 1 - 10 of 8615 matches for " magnetic submicron particles "
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Facile one-step coating approach to magnetic submicron particles with poly(ethylene glycol) coats and abundant accessible carboxyl groups
Long GB, Yang XL, Zhang Y, Pu J, Liu L, Liu HB, Li YL, Liao F
International Journal of Nanomedicine , 2013, DOI: http://dx.doi.org/10.2147/IJN.S41411
Abstract: cile one-step coating approach to magnetic submicron particles with poly(ethylene glycol) coats and abundant accessible carboxyl groups Original Research (601) Total Article Views Authors: Long GB, Yang XL, Zhang Y, Pu J, Liu L, Liu HB, Li YL, Liao F Published Date February 2013 Volume 2013:8 Pages 791 - 807 DOI: http://dx.doi.org/10.2147/IJN.S41411 Received: 11 December 2012 Accepted: 10 January 2013 Published: 25 February 2013 Gaobo Long,1,* Xiao-lan Yang,1,* Yi Zhang,1 Jun Pu,2 Lin Liu,1 Hong-bo Liu,1 Yuan-li Li,1 Fei Liao1 1Unit for Analytical Probes and Protein Biotechnology, Key Laboratory of Clinical Laboratory Diagnostics of the Education Ministry, College of Laboratory Medicine, 2Department of Urology, the First Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China *These authors contributed equally to this work Purpose: Magnetic submicron particles (MSPs) are pivotal biomaterials for magnetic separations in bioanalyses, but their preparation remains a technical challenge. In this report, a facile one-step coating approach to MSPs suitable for magnetic separations was investigated. Methods: Poly(ethylene glycol) (PEG) was derived into PEG-bis-(maleic monoester) and maleic monoester-PEG-succinic monoester as the monomers. Magnetofluids were prepared via chemical co-precipitation and dispersion with the monomers. MSPs were prepared via one-step coating of magnetofluids in a water-in-oil microemulsion system of aerosol-OT and heptane by radical co-polymerization of such monomers. Results: The resulting MSPs contained abundant carboxyl groups, exhibited negligible nonspecific adsorption of common substances and excellent suspension stability, appeared as irregular particles by electronic microscopy, and had submicron sizes of broad distribution by laser scattering. Saturation magnetizations and average particle sizes were affected mainly by the quantities of monomers used for coating magnetofluids, and steric hindrance around carboxyl groups was alleviated by the use of longer monomers of one polymerizable bond for coating. After optimizations, MSPs bearing saturation magnetizations over 46 emu/g, average sizes of 0.32 μm, and titrated carboxyl groups of about 0.21 mmol/g were obtained. After the activation of carboxyl groups on MSPs into N-hydroxysuccinimide ester, biotin was immobilized on MSPs and the resulting biotin-functionalized MSPs isolated the conjugate of streptavidin and alkaline phosphatase at about 2.1 mg/g MSPs; streptavidin was immobilized at about 10 mg/g MSPs and retained 81% ± 18% (n = 5) of the specific activity of the free form. Conclusion: The facile approach effectively prepares MSPs for magnetic separations.
Modeling Submicron Particles Collection in Laminar Forced Convection Gas Flow by a Rectangular Venturi Scrubber  [PDF]
Serge Wendsida Igo, Kokou N’wuitcha, Belkacem Zeghmati, Xavier Chesneau
Open Journal of Air Pollution (OJAP) , 2016, DOI: 10.4236/ojap.2016.51002
Abstract: Venturi scrubbers are usually used for large particles cleaning in turbulent gaseous flow. In this work, submicron particles scrubbing in laminar forced convection dusty air flow in a rectangular venturi scrubber have been numerically simulated. Hydrodynamics effects and scrubbing process are investigated in detail. Results are presented as flow velocity, axial pressure, streamlines pattern, particles and droplets mass fraction profile, and collect efficiency. They show that venturi scrubbers can be efficient for submicron particles scrubbing. In fact, a better collect efficiency is obtained at high particles-droplets residence time, high ratio droplets concentration/particles concentration, low venturi diameter ratioand low Reynolds numbers. There is a critical Reynolds number value for which the collect efficiency becomes very low and tends to be constant.
Degradation of Diclofenac in Molecularly Imprinted Polymer Submicron Particles by UV Light Irradiation and HCl Acid Treatment  [PDF]
Mohammad Hassanzadeh-Khayyat, Edward P. C. Lai, Kerim Kollu, Banu Ormeci
Journal of Water Resource and Protection (JWARP) , 2011, DOI: 10.4236/jwarp.2011.39074
Abstract: A new molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization using diclofenac (DFC) as a template. Binding characteristics of the MIP particles were evaluated by equilibrium binding experiments. DFC-MIP aqueous suspension and non-imprinted polymer (NIP) suspension were exposed to monochromatic UV light (253.7 nm) from low-pressure mercury lamps. UV-visible spectrophotometry (especially absorbance at 276 nm) showed that the DFC inside MIP particles degraded completely. After DFC-MIP suspension exposure to UV light the particles were completely regenerated after washing with water at least six times. The regenerated MIP particles rebounded considerable amount of DFC (approximately 88% removal of 44 ppm DFC). The stability of DFC was examined in the presence of various concentrations of hydrochloric acid (0.025 to 125 mM). Experimental results showed that degradation of DFC was efficient, depending on the acid concentration as well as the treatment time. However, there was no re-binding of DFC by the MIP particles after HCl treatment (and DDW washing) when exposed to DFC for 24 hours.
Measurement of the Lubricant Properties Using Hall Effect Sensor: A Study on Contamination and Viscosity  [PDF]
Witsarut Sriratana, Riichi Murayama
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.54051

This study proposes the development of contamination measurement for industrial machines based on magnetic field method. A permanent magnet was used to generate the 0.17 T magnetic fields and Hall Effect sensor was applied to measure the contamination level of metal particles in industrial machine lubricant during operation time and to predict the replacement period if the lubricant condition does not meet the standard (NAS 1638). Contamination level of metal particles was directly related to the output voltage of Hall Effect sensor. When there was any movement of metal particles to the permanent magnet, the measured result was then transferred to a computer for analysis. This methodology could be applied to experiment the conditions of used lubricant for assessing the contamination and the metal particle remaining in the tank or inside the pipe of the machine as well as the conditions of car lubricant and other lubricants used in industrial processes.

Study on Optimizing High-Gradient Magnetic Separation—Part 2: Experimental Evaluation of the Performance of a New Designed Magnetic Filter  [PDF]
Yonas S. Shaikh, Christian Seibert, Percy Kampeis
World Journal of Condensed Matter Physics (WJCMP) , 2016, DOI: 10.4236/wjcmp.2016.62017
Abstract: The introduction of functionalized magnetizable particles and high-gradient magnetic separation represents a time and money saving alternative to conventional purification and separation unit operations in the biotechnical sector. This technique has some advantages especially for the recycling of immobilized enzymes. A new magnetic filter with sight glasses was constructed and produced to study the performance of high-gradient magnetic separation at varied parameters. By optical analysis the buildup of a clogging was identified as the major parameter which affected the separation performance. For the cleaning procedure, a two-phase flow of water with highly dispersed air bubbles was tested which led to a nearly complete cleaning of the filter chamber.
Innovative approach to uniform imprint of micron and submicron features
H. Hoch,T.T. Wen
Journal of Achievements in Materials and Manufacturing Engineering , 2008,
Abstract: Purpose: To develop methods for uniform imprint of micron and submicron-scale features.Design/methodology/approach: The first is gas-assisted imprint technique. In use of gas to exert isotropic pressure in hot embossing, uniform embossing throughout the area is achieved. Another approach is the electromagnetic force-assisted imprinting technology, which employs the electromagnetic force to pull the magnetic stamp with submicron-scale structures into a UV-curable resist on the substrate. The liquid photopolymer is then cured by UV-irradiation at room temperature. Furthermore, the ferromagnetic UV-curable material is made of nano-Fe powder and UV-curable polymer. The micron and submicron-scale magnetic features can be fabricated.Findings: Uniform embossing throughout the area is achieved. Under the condition of 180 C, 40kgf/cm2 and 90 seconds, high quality and uniformity of micro-optical components can be fabricated. For electromagnetic force-assisted imprinting technology, a large area of sub-micron pattern with a line width of 502nm and a pitch of 1um can be successfully fabricated under the condition of pressure of 1.6kgf/cm2 for 30 seconds and UV curing for 0.5 minute. Using ferromagnetic UV-curable resist, the structures can be successfully fabricated under the pressure of 0.92kgf/cm2 with the same UV-curable time. These results indicate good uniformity and controllability on both the gas-assisted hot embossing and electromagnetic force-assisted imprinting for efficient fabrication of micron- or submicron-scale structures.Practical implications: The facilities have been designed, constructed and tested. The effects of processing parameters including the processing temperature, pressure, and time on the replication quality were investigated.Originality/value: There are advantages of high uniformity, low pressure and low temperature for various applications in micron and sub-micron features and other micro-optical components such as gratings and waveguides etc.
Purification, Immobilization and Characterization of Lipase Isoenzyme from Aspergillus niger with C8 Magnetic Particles  [PDF]
Samanta Hernández-García, María Inmaculada García-García, Francisco García-Carmona
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.57075

The purification of a lipase isoenzyme from an Aspergillus niger lipase A is reported in this manuscript. Purification was carried out in a simple adsorption step, in which the lipase was offered at low ionic strength to the commercially available C8 modified magnetic particles, MaKProt C8. When the isoenzyme was desorbed with a 0.2% solution of Triton X-100, the SDS-PAGE gel showed a single pure band with a molecular weight of 35 KDa. The purified fraction showed 66.75-fold purification compared with the crude extract. The pure fraction was characterized along with the crude extract and the lipase adsorbed on the MaKProt C8. The purified and the adsorbed lipase showed better activity for the tested substrates (p-nitrophenyl acetate, decanoate, myristate and palmitate) than the crude extract, the preferred substrates being myristate (26.7 μmol·min-1·mg-1) and decanoate (17.4 μmol·min-1·mg-1), respectively. The temperature and pH profiles showed no change for the three enzymes, the optimum temperature being 37°C and the best pH 7.0.

Magnetic Properties of Spherical Collectors in a Transverse Magnetic Filter
K. Wiangnon,C. Polyon
Science Journal Ubon Ratchathani University , 2010,
Abstract: A transverse magnetic filter was designed and built. The magnetic properties of spherical collectorsused in the filter were discussed. The magnetic filtration experiments were performed with Fe powder,used as magnetic particles, suspended in fluid flow in the direction perpendicular to an external uniformmagnetic field between 0 mT and 109 mT. In this work, the collectors with different sizes: diameters of3.455 mm, 4.789 mm or 6.369 mm were used to capture the magnetic particles coming to the filter. Themagnetic properties of the collectors were discussed in filter efficiency terms versus the previousapplied filed. By comparison, experimental results show that the filter efficiency of a lower diameter isgreater than that of a higher diameter.
Study on Optimizing High-Gradient Magnetic Separation—Part 1: Improvement of Magnetic Particle Retention Based on CFD Simulations  [PDF]
Yonas S. Shaikh, Christian Seibert, Percy Kampeis
World Journal of Condensed Matter Physics (WJCMP) , 2016, DOI: 10.4236/wjcmp.2016.62016
Abstract: The introduction of functionalized magnetizable particles for the purification of enzymes or for the multi-use of pre-immobilized biocatalysts offers a great potential for time and cost savings in biotechnological process design. The selective separation of the magnetizable particles is performed for example by a high-gradient magnetic separator. In this study FEM and CFD simulations of the magnetic field and the fluid flow field within a filter chamber of a magnetic separator were carried out, to find an optimal separator design. The motion of virtual magnetizable particles was calculated with a one-way coupled Lagrangian approach in order to test many geometric and parametric variations in reduced time. It was found that a flow homogenisator smoothed the fluid flow, so that the linear velocity became nearly equal over the cross section in the direction of flow. Furthermore the retention of magnetizable particles increases with a high total edge length within the filter matrix.
Preparation of Gelatin Submicron Particles with Emulsion Method

CAI Meng-jun,ZHU Yi-hua,YANG Xiao-ling,

过程工程学报 , 2005,
Abstract: Gelatin submicron particles were prepared by emulsion chemical cross-linking method using gelatin (type A) as core material and paraffine as oil phase. The morphology and particle size of gelatin submicron particles were observed by scanning electron microscopy (SEM). The effects of gelatin concentration, emulsion stirring speed, emulsion temperature, emulsifier and cross-linking agent on particle size distribution, were investigated. The results show that increasing gelatin concentration, enhancing emulsion and using mixed emulsifier can decrease the gelatin submicron particle diameter using glutaraldehyde as cross-linking agent. In addition, the gelatin submicron particles with an average particle size about 450 nm and an orbicular spheric morphology were produced by using a high emulsion stirring speed of 7000 r/min in the optimum procedure.
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