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Totally found 383 items.

  • [期刊] REMOVAL OF AGGREGATES FROM MICRON-SIZED POLYMETHYL METHACRYLATE (PMMA) LATEX BEADS USING FULL FEED DEPLETION MODE OF GRAVITATIONAL SPLITT FRACTIONATION (FFD-GSF)
    Split-flow thin cell (SPLITT) fraclionation (SF) provides separation of colloidal particles or macromolecules into two fractions. A gravitational SF(GSF) system was constructed and Us applicability was tested for removal of aggregates from mass-produced polymelhyl methacrylate (PMMA) latex beads. The full-feed depletion (FFD) mode of GSF (FFD-GSF) was found to be a simpler alternative to the conventional mode for removal of the aggregates. Unlike in the conventional mode, where two inlets are used for feeding of the sample suspension and the carrier liquid respectively, only one inlet (for the sample feeding) is used in the FFD mode, allowing easier control of the flow rate. Also the sample suspension is not diluted during FFD mode operation. Aggregated particles were found only in one of the two fractions, allowing removal of the aggregates. The sample was continuously fed into the GSF system, showing potential application to a large quantity operation for removal of the PMMA aggregates.
  • [期刊] Mechanical and In Vitro Antibacterial Properties of a Porous Ti–6Al–4V Scaffold Combined with Vancomycin-Loaded Polymethyl Methacrylate by Three-Dimensional Printing
    The study aims to investigate the construction and efficacy of a 3D-printed antibiotic scaffold through the combination of vancomycin-loaded polymethyl methacrylate with a 3D-printed porous titanium scaffold. The titanium scaffolds were constructed with orthogonal micro-structures usingselective laser melting and the micro-pores were filled with vancomycin-loaded polymethyl methacrylate while the polymethyl methacrylate was in its liquid phase. Structural features, the release of antibiotics, and the antibacterial performance of vancomycin-loaded polymethyl methacrylate-titaniumscaffolds were measured and compared with a titanium-free control group. Tests were also conducted to determine the loading force, deformation, and maximum pressure that the three different scaffolds could withstand. The results demonstrate that vancomycin-loaded polymethyl methacrylate maypermeate into the pores of a 3D-printed titanium scaffold, which allows the vancomycin-loaded polymethyl methacrylate-titanium scaffold to remain active over a longer period and have a stronger effect on Staphylococcus aureus populations than a vancomycin-loaded polymethyl methacrylateblock (P < 0.05). The vancomycin-loaded polymethyl methacrylate-titanium scaffold also has greater biomechanical strength than its constituents. These results suggest that selective laser meltingis a promising technique for producing porous 3D-printedtitanium scaffolds and that maybe efficient and reliable in the treatment of bone infection when impregnated with vancomycin-loaded polymethyl methacrylate.
  • [期刊] Controlled Release of Necrostatin-1 from Calcium Phosphate-Polymethyl Methacrylate Bone Cement
    Objective : To evaluate the release of Necrostatin-1 (Nec-1) in bone cement mixed by different proportions of calcium phosphate cement (CPC) and polymethyl methacrylate (PMMA) in vitro , and to optimize the mixture proportion of CPC-PMMA. Methods : CPC and PMMA powderare mixed at the ratio of 0:1, 1:1, 2:1, and 3:1, with 5.18 mg of Nec-1 as 4 groups (0:1 group, 1:1 group, 2:1 group, 3:1 group). The mixed bone cement samples are produced by same standard (height of 12 mm and an inner diameter of 6 mm). All the bone cement samples are tested by X-ray diffraction,compression test, solidification time, electron microscope scanning and the detection of Nec-1 release in vitro . The activity of releasing Nec-1 was deteted by culturing with MC3T3-E1 cells and then necrotic apoptosis cells were tested via Flow cytometry. Results : Nec-1, CPCand PMMA do not affect each other's material generation after the analysis of their mixture structure. With the increase of the proportion of CPC, the compressive strength of CPC-PMMA bone cement mixed with Nec-1 is gradually reduced and the time of solidification is prolonged. The distancebetween the PMMA particles in 0:1 group, 1:1 group, 2:1 group, and 3:1 group are about 0 μ m, 100–200 μ m, 100–400 μ m, 100–400 μ m, respectively. By comparing the cumulative release of Nec-1 in the four groups, the release of 0:1 groupis at the lowest level, and the rank of release rate is 3:1 group>2:1 group>1:1 group. It is clear that the release of Nec-1 is fast in 5 days in each group, become slower from 5 to 19 days and continuously decelerate after 19 days. The amount of Nec-1 release reaches the highest pointat 19 days. The cumulative release concentration of Nec-1 of 0:1 group, 1:1 group, 2:1 group and 3:1 group in 59 days are 13.72 um/L, 286.66 um/L, 405.96 um/L and 553.77 um/L, respectively. The cumulative release percentages are respectively 0.34%, 7.17%, 10.15% and 13.84%. Through testingthe necrotic apoptosis cells via Flow cytometry, the releasing Nec-1 still remains activity. Conclusions : This study has verified that CPC-PMMA bone cement mixture has a better comprehensive performance than simple PMMA bone cement, and established a methodology for detection of Nec-1release in bone cement in vitro . In this study, Nec-1-CPC-PMMA bone cement mixture with the CPC to PMMA ratio of 3:1 showed the optimal compressive strength and coagulation time. And the mixture can release Nec-1 stably and the releasing Nec-1 maintains activity, thus this configurationwould be an ideal choice for the preparation of a new type of Nec-1-CPC-PMMA bone cement.]]>
  • [期刊] Reduced graphene oxide/polymethyl methacrylate (rGO/PMMA) nanocomposite for real time gamma radiation detection
    Novel 3 dimensional radiation sensors using reduced graphene oxide (rGO) nanoflakes in polymethyl methacrylate matrix as sensing material were synthesized and fabricated to measure the dose rate of gamma radiation. A detailed characterization of the prepared reduced graphene oxide using X-ray diffraction (XRD), thermal gravimetric analysis (TGA), atomic force microscopy (AFM), Field Emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR) and High-resolution transmission electron microscopy (HRTEM) is presented. Reduced graphene oxide-polymethyl methacrylate composite was prepared using methylene chloride solvent-assisted dispersion of nano flakes of reduced graphene oxide in the polymer matrix. The gamma sensor mainly consists of polymethyl methacrylate/reduced graphene oxide (rGO/PMMA) nanocomposite as the sensing material and two silver coated glass electrodes to make a conductive cell. Real time dose rate information of the nanocomposite such as linearity response to dose rate and sensitivity are investigated. rGO/PMMA based gamma sensors show better performance at a standard bias voltage with respect to graphene oxide (GO) dosimeters. The response to dose rate is linear in the range of 50-130 mGy/min and the sensor array can be introduced for gamma radiation application dosimetry in diagnostic activities.
  • [期刊] On Mechanism of Liquid Water Isothermic segregation in a medium of highly elastic hydrophobic polymers (polymethyl methacrylate)
    Deglassifying the films of plasticized polymethyl methacrylate (PMMA) in heated water causes the spontaneous segregation of water drops of micrometer and over in radius and is accompanied by a change in the film sizes. This process is impossible in structureless hydrophobic systems and points to the structural organization of the polymer chains, which are responsible for adsorption of a certain amount of molecular water by hydrophobic PMMA. From a thermodynamic standpoint, "structural hydrophily" is of en tropic nature and is provided by the micro pore generation due to the fluctuation. The micropores are stabilized owing to the capture of water molecules. When the polymer transforms to the highly elastic state, zones of a dynamically active microporous sponge are formed in it with the moisture participation. In these zones, the fluctuation results in the formation and destruction of hydrophobic slits which ensure the appearance of the water interlayers and drops of critical size that merge into the stable water phase. A thermodynamic model of the process is considered.
  • [期刊] REMOVAL OF AGGREGATES FROM MICRON-SIZED POLYMETHYL METHACRYLATE (PMMA) LATEX BEADS USING FULL FEED DEPLETION MODE OF GRAVITATIONAL SPLITT FRACTIONATION (FFD-GSF)
    Split-flow thin cell (SPLITT) fraclionation (SF) provides separation of colloidal particles or macromolecules into two fractions. A gravitational SF(GSF) system was constructed and Us applicability was tested for removal of aggregates from mass-produced polymelhyl methacrylate (PMMA) latex beads. The full-feed depletion (FFD) mode of GSF (FFD-GSF) was found to be a simpler alternative to the conventional mode for removal of the aggregates. Unlike in the conventional mode, where two inlets are used for feeding of the sample suspension and the carrier liquid respectively, only one inlet (for the sample feeding) is used in the FFD mode, allowing easier control of the flow rate. Also the sample suspension is not diluted during FFD mode operation. Aggregated particles were found only in one of the two fractions, allowing removal of the aggregates. The sample was continuously fed into the GSF system, showing potential application to a large quantity operation for removal of the PMMA aggregates.
  • [期刊] Polymethyl methacrylate (PMMA) point of care for ABO-Rh(D) blood typing
    Polymethyl methacrylate (PMMA) based point of care (POC) for ABO-Rh(D) blood grouping by the naked eye was investigated. PMMA substrate was covalently linked with carboxyl methyl dextran (CMD) and coupled to the blood group specific antibodies anti A, anti B, and anti D, which were patterned into "A", "B", and "+". The red read out color originated from the color of hemoglobin in the ABCs. The major human blood group, ABO-Rh (D), was successfully sorted using these patterns. PMMA strip-based assays for blood grouping by the naked eye resulted in correct blood group identification of all 74 samples in comparison to slide agglutination test. The determination of captured RBC Rh(D) required a longer reaction time with immobilized anti D antibody on the PMMA substrate than other blood groups to produce sufficient color for unambiguous visual identification. The proper RBC concentration was found to be higher than 1% v/v for naked eye detection. The dilution of blood sample is playing a crucial role in reducing interference from blood proteins during detection. A used of undiluted blood sample for the testing should be avoided. The proper blood dilution was found to be 10% or 1:10 dilution. The proposed technique presents a quick, cheap, simple, and almost instantaneous assay for blood grouping.
  • [期刊] REMOVAL OF AGGREGATES FROM MICRON-SIZED POLYMETHYL METHACRYLATE (PMMA) LATEX BEADS USING FULL FEED DEPLETION MODE OF GRAVITATIONAL SPLITT FRACTIONATION (FFD-GSF)
    Split-flow thin cell (SPLITT) fraclionation (SF) provides separation of colloidal particles or macromolecules into two fractions. A gravitational SF(GSF) system was constructed and Us applicability was tested for removal of aggregates from mass-produced polymelhyl methacrylate (PMMA) latex beads. The full-feed depletion (FFD) mode of GSF (FFD-GSF) was found to be a simpler alternative to the conventional mode for removal of the aggregates. Unlike in the conventional mode, where two inlets are used for feeding of the sample suspension and the carrier liquid respectively, only one inlet (for the sample feeding) is used in the FFD mode, allowing easier control of the flow rate. Also the sample suspension is not diluted during FFD mode operation. Aggregated particles were found only in one of the two fractions, allowing removal of the aggregates. The sample was continuously fed into the GSF system, showing potential application to a large quantity operation for removal of the PMMA aggregates.
  • [期刊] Novel reparation method for polymethyl methacrylate optical windows of aircrafts damaged by service environment
    The optical properties of polymethyl methacrylate(PMMA) with varying degrees of artificial scratches have been studied with the aim of reproducing the change of visibility of an aircraft's PMMA optical windows after being damaged in their service environment. A novel maintenance method that can perfectly restore the optical property of PMMA has been identified and employed in the repair of the scratches that are formed on the surface of PMMA. This convenient and low-cost method entails polishing PMMA with different types of sandpaper to remove the scratches, and then spin-coating the repair solution in order to restore the optical properties of PMMA. The effect of this repair mechanism and parameters of the repair process were studied.The results indicated that the optical performance of PMMA is closely related to the mesh size of sandpaper, and improper parameter selection destroys the general effect of the repair. When the number of sandpaper mesh is low, the size of the abrasive particle is relatively larger, which can cause deeper friction marks on the surface of PMMA optical windows. Surface treatment using 5000 mesh sandpaper lowers surface roughness(R——a=0.566 nm), and optical transmittance in visible range can be restored to more than 88%.
  • [期刊] Study of Effects Occurring on Formation of Fractal Microstructures in Layers of Polycarbonate, Polymethyl Methacrylate, Indium Tin Oxide, and Zinc Oxide
    The effects occurring on the formation of fractal microstructures in conductive layers of oxide compounds are investigated. It is demonstrated that during a high-density current flow in the layers of indium tin oxides (ITOs) placed on glass substrate a dynamic system is formed with the subsequent formation of a current channel on the layer's surface, which determines the path of the development of fractal microstructures. Fractal microstructures of varied shapes (spiral, sectoral, and radial) were formed. It is shown that application of an additional polymer thin film on the layers of oxide compounds visualizes the breakdown processes occurring within the structure. Magnified polymer imaging allows to estimate the quality of the layers in contact without high resolution optical equipment. The emergence of luminescence related to the relaxation of excited atoms is identified as the most crucial effect following the formation of fractal structures. This analytical signal is promising in terms of the analysis of the processes of the formation of fractal structures.
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