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Totally found 13982 items.

  • [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] Ammonium persulphate induced synthesis of polymethyl methacrylate grafted sodium alginate composite films with high strength for food packaging
    The graft copolymerization of methyl methacrylate (MMA) onto alginate was carried out in aqueous media by initiators of ammonium persulphate under a nitrogen gas atmosphere. Then, the grafting of PMMA chains onto the alginate backbone was confirmed through the study of Fourier transform infrared, X-ray diffraction, scanning electron microscopy and H-1 nuclear magnetic resonance spectroscopy. At last, a thin and transparent polymethyl methacrylate grafted alginate film with high strength was obtained by the casting method. The effect of MMA/SA ratio or percentage of graft (G%) on mechanical properties, thermal stability (thermogravimetric analysis/differential thermogravimetry analyses), color, opacity and water resistance of composite films were characterized. Results showed the homogeneous transparent films could be obtained while G% was lower than 8.64%. After being grafted by PMMA, the tensile strength of the films was distinctly improved by 205.3%, as well the elongation at break (E%) by 41.7% while the MMA/SA (g/g) is 0.3. On the other hand, water resistance, thermal stability and crystallinity of the films were improved, however, the transparency was slightly decreased. (C) 2018 Published by Elsevier B.V.
  • [期刊] Deagglomeration in Eu~(3+)-activated Li_2Gd_4(MoO_4)_7 polycrystalline incorporated polymethyl methacrylate
    Li2Gd4(MoO4)(7): Eu3+/PMMA composite flakes (LGMP: Eu3+) have been obtained via embedding Eu3+-activated LGM polycrystalline precursor powders into polymethyl methacrylate (PMMA). The precursor powder with a size of similar to 7 mu m is confirmed to form the sea-island-like structure by SEM, which is helpful to the stability of the particle-polymer coexistence network in LGMP: Eu3+ flakes. Differential photon-generating behaviors are revealed under short-wave radiation and the effectiveness of PMMA is verified in reducing the mutual collision probability and avoiding the powder agglomeration. Although the LGMP: Eu3+ system has lower powder content in contrast to the pure precursor, its luminosity is still comparable to the pure one due to its favorable particle dispersibility. Efficient photon-conversion and intense red-emission indicate the organic-inorganic composite of PMMA loaded LGM: Eu3+ system is a potential candidate for solid-state lighting and color displays.
  • [期刊] Suppression of nano-polymethyl methacrylate dust explosions by ABC powder
    The suppression effects of ABC powder on 100 nm polymethyl methacrylate (PMMA) dust explosions with different mass densities were experimentally studied. Results showed that the suppressed flames were dim and the flame propagation was slowed down with the addition of ABC powder. When the proportion of suppressant increased, the average propagation velocity was decreased. After adding 30% ABC powder to 650 g/m(3) PMMA dust cloud, the maximum suppression ratio for velocity was 93%. After adding 10% ABC powder, the temperatures of PMMA dust cloud with the mass densities of 250 g/m(3), 450 g/m(3) and 650 g/m(3) were decreased to 19.8%, 27.4% and 33.1%, respectively. Meanwhile, the critical suppression proportion of PMMA dust explosion with three mass densities were 25%, 35% and 35%. Thermal analysis results showed that the addition of suppressant could increase the thermal stability of PMMA. The suppression mechanisms were comprised of physical suppression and chemical suppression which reflected on the consumption of H and OH radicals. The chemical kinetic models indicated that PO2 and HOPO played a catalytic role in the combination of H and OH. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
  • [期刊] Reinforcement of polymethyl methacrylate denture base resin with ZnO nanostructures
    Polymethyl methacrylate-zinc oxide (PMMA/ZnO) nanocomposites with different ZnO morphology and quantities were prepared by insitu curing of MMA/PMMA used in denture base material in the presence of ZnO nanostructured materials. The composition, structure, and morphology of the nanocomposites were characterized by Fourier-Transform infrared spectra (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The effect of ZnO morphology and contents on the mechanical properties including impact, flexural, and hardness was studied. The results demonstrated that the mechanical and thermal properties of denture base materials were improved by incorporation of nano-sized ZnO into the polymethyl methacrylate matrix. The impact strength was highly improved upon using ZnO nanotubes. However, the flexural strength was improved using ZnO nanospheres.
  • [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] 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] Toughness of Scots pine - polymethyl methacrylate composite
    A series of 1,600 samples of the sapwood of Scots pine (Pinus sylvestris), part of them in natural state, but majority subjected to polymerization with various level of impregnation with methyl methacrylate, were tested for toughness on Charpy's impact machine. The goal of the experiment was to investigate how polymerization improves toughness and, additionally, how exposure to low temperatures and to the action of seawater influences this property of the material tested. It was found that within impregnation levels and temperatures tested variability of toughness due to these two factors is almost linear and in practical considerations may be predicted based on an empirical formula. It was also found that exposure to the action of seawater weakens the material. To verify anisotropy of toughness in the plane perpendicular to the grain all samples were consistently cut out such that one pair of opposite lateral faces were tangent to the growth rings. Half of the whole set of samples was fractured with an impact directed perpendicular to the growth rings and the other half with an impact directed in the tangential direction. The results show that although in general toughness is slightly higher in the direction perpendicular to the growth rings than in the tangent direction, the difference may be neglected in practical considerations. POLYM. COMPOS., 40:811-822, 2019. (c) 2018 Society of Plastics Engineers
  • [期刊] Optimum creep lifetime of Polymethyl Methacrylate (PMMA) tube using rheological creep constitutive models based on experimental data
    In this paper, the creep behavior of Polymethyl Methacrylate (PMMA) is investigated both experimentally and numerically at different temperatures (30, 40 and 50 degrees C) and stress levels. The experimental results show that PMMA has a nonlinear viscoelastic behavior. Hence, to model the creep behavior of PMMA, three types of constitutive models have been proposed: a) the generalized time hardening model, b) Burgers model, c) modified Burgers model. It was found that the generalized time hardening model, which has extensive applications in commercial softwares, predicts the creep behavior of PMMA at higher stress levels but it deviates from the experimental results at lower stress levels. Although, Burgers model predicts the creep behavior of PMMA, to improve the accuracy of the model a modified version of Burgers model has been proposed, which demonstrates very good consistency with the experimental data over the whole range of applied stresses and temperatures. Finally, the results are used to estimate the optimum creep lifetime of a rotating pressurized tube. A set of diagrams, which can be used in industry, have been produced based on each model.
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