The ablation parameters such as threshold fluence, etch depth, ablation rate and the effect of material targets were investigated under the interaction of laser pulse with low intensity. The parameters of the laser sy...The ablation parameters such as threshold fluence, etch depth, ablation rate and the effect of material targets were investigated under the interaction of laser pulse with low intensity. The parameters of the laser system are: laser pulse energy in the range of 110–140 m J, wavelength1064 nm and pulse duration 20 ns. By macroscopic estimation of the outward images of the ablation and data obtained, we can conclude that the photothermal and photoionization processes have more influence for aluminum ablation. In contrast, for polymer samples, from the macroscopic observation of the border pattern at the irradiated spot, and also the data obtained from the experiment results, we deduce that both chemical change due to heating and photochemical dissociation were effective mechanisms of ablation. However, concerning the two polymer samples, apart from considering the same theoretical ablation model, it is conceived that the photomehanical specifications of PMMA are involved in the ablation parameters. The threshold fluence for an ablation rate of 30 laser shots were obtained as 12.4, 24.64, and 11.71 J cm^(-2), for aluminum, silicon rubber and polymethylmethacrylate(PMMA) respectively.The ablation rate is exponentially decreased by the laser-shot number, especially for aluminum.Furthermore, the etch depth after 30 laser shots was measured as 180, 630 and 870 μm, for aluminum, silicon rubber and PMMA, respectively.展开更多
Polymethylmethacrylate(PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950 s to the recent advent of nanoparticle additives. Additives have been trialed to address problem...Polymethylmethacrylate(PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950 s to the recent advent of nanoparticle additives. Additives have been trialed to address problems with modern bone cements such as the loosening of prosthesis, high post-operative infection rates, and inflammatory reduction in interface integrity. This review aims to assess current additives used in PMMA bone cements and offer an insight regarding future directions for this biomaterial. Low index(< 15%) vitamin E and low index(< 5 g) antibiotic impregnated additives significantly address infection and inflammatory problems, with only modest reductions in mechanical strength. Chitosan(15% w/w PMMA) and silver(1% w/w PMMA) nanoparticles have strong antibacterial activity with no significant reduction in mechanical strength. Future work on PMMA bone cements should focus on trialing combinations of these additives as this may enhance favourable properties.展开更多
Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix ma...Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape;however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.展开更多
PMMA films in the high global chain orientation and nearly random segmental orientation(GOLR) state were prepared by uni-axially drawing at temperatures 20～30℃ above its glass transitiontempefature, T_g, and their i...PMMA films in the high global chain orientation and nearly random segmental orientation(GOLR) state were prepared by uni-axially drawing at temperatures 20～30℃ above its glass transitiontempefature, T_g, and their isotropic and anisotropic properties were studied. Experimental results show thatthis kind of amorphous state, the GOLR state, is nearly isotropic in optical birefringence, IR-dichroism andX-ray diffraction patterns, but is very anisotropic in behaviors of thermal expansion, solvent-swelling andstress-strain.展开更多
Introduction: To investigate a long-term in vivo deterioration of polymethylmethacrylate (PMMA) bone cement over time, we evaluated retrieved PMMA cement in terms of chemical elements presenting in the cement using en...Introduction: To investigate a long-term in vivo deterioration of polymethylmethacrylate (PMMA) bone cement over time, we evaluated retrieved PMMA cement in terms of chemical elements presenting in the cement using energy dispersive analysis of X-rays;Knoop hardness;and the Young’s modulus using scanning acoustic microscopy. Materials and Methods: For mechanical evaluation, we could neglect the influences of entrapped air bubbles or blood by the use of small specimens. The study was based on thirteen cement samples (six used in the acetabulum and seven in the femur) derived from eight patients (age at revision surgery: mean 72.5, range 68 to 79). All of these samples were Simplex-P?cement. They were functioning well at least ten years after the previous surgery. Duration until revision surgery was ranged 12 to 25 years (average, 17.4 years). The reason for revision was aseptic mechanical loosening. Twenty samples of Simplex-Preg;cement were served by manually mixing as a control. Results: The average of the hardness of the cement was 17.0 ± 1.2 (range, 13.4-20.6). In the control, the hardness was 17.8 ± 1.5 (range, 14.0-24.6). There was no significant difference between these values. The mean of Young’s modulus of the cement was 5.61 ± 0.19 GPa (range, 5.09-6.10). In the control, the modulus was 6.04 ± 0.13 GPa (range, 5.68-6.45). Although the modulus was significantly less than that of the control, there was only 7% decrease in average between twelve and twenty-five years in vivo. Conclusions: Our results suggest that long-term implantation and functional loading in vivo may not be the limiting factor in the mechanical integrity of the bone cement.展开更多
Polymethylmethacrylate (PMMA) is highly regarded for its transparency, and is used in such products as cameras and Video Tape Recorders as plastic lenses to take advantage of its excellent optical properties. Also, it...Polymethylmethacrylate (PMMA) is highly regarded for its transparency, and is used in such products as cameras and Video Tape Recorders as plastic lenses to take advantage of its excellent optical properties. Also, it is used in numerous other industrial fields like automobile lamp lenses, billboards, and lighting equipment. The phenomenon of environmental stress cracking is known to occur in PMMA due to ethanol, and there are cases when this may become a factor which causes damage of molded products. In the present paper, upon close observation by using the method of chemiluminescence in order to elucidate the mechanism by which this environmental stress cracking occurs, we report that we are able to capture the formation of a radical at the moment of cracking.展开更多
Chemical modifications by incorporating organic dye molecules in polymethylmethacrylate (PMMA) matrix may open up the possibility of the development of smart materials. In the present work, Kiton red-620 laser dye is ...Chemical modifications by incorporating organic dye molecules in polymethylmethacrylate (PMMA) matrix may open up the possibility of the development of smart materials. In the present work, Kiton red-620 laser dye is embedded in synthesized PMMA matrix by chemical doping process. The spectral investigations of Kiton red-620 doped PMMA matrix has been carried out using FTIR, UV-visible and photoluminescence spectrophotometers. FTIR study showed that the absorption band region 1800 - 1000 cm-1 becomes sharper with the concentration of dye in PMMA matrix. UV-visible and photoluminescence study showed that a slight shifting appears in the absorption spectra, emission spec- tra and intensity of emission peaks as concentration of dye increases in PMMA matrix.展开更多
The solid-state medium containing pyrromethene 567 (PM567) in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation.The experimental setup is an ordinary industrial product without spe...The solid-state medium containing pyrromethene 567 (PM567) in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation.The experimental setup is an ordinary industrial product without special design.The bulk transmission losses,the output energy,and the other lasing properties are compared.The medium with the lowest transmission loss,measured to be 0.392 %/cm at 633 nm,gives a laser output of 130 mJ with a slope efficiency of 0.082%.展开更多
We report a rare complication of diffuse alveolar hemorrhage and respiratory failure following percutaneous vertebroplasty in a patient who has evidence of cement leakage. Cement injection was done two days prior to p...We report a rare complication of diffuse alveolar hemorrhage and respiratory failure following percutaneous vertebroplasty in a patient who has evidence of cement leakage. Cement injection was done two days prior to presentation and covered 2 vertebral levels for osteoporosis induced fractures.展开更多
文摘The ablation parameters such as threshold fluence, etch depth, ablation rate and the effect of material targets were investigated under the interaction of laser pulse with low intensity. The parameters of the laser system are: laser pulse energy in the range of 110–140 m J, wavelength1064 nm and pulse duration 20 ns. By macroscopic estimation of the outward images of the ablation and data obtained, we can conclude that the photothermal and photoionization processes have more influence for aluminum ablation. In contrast, for polymer samples, from the macroscopic observation of the border pattern at the irradiated spot, and also the data obtained from the experiment results, we deduce that both chemical change due to heating and photochemical dissociation were effective mechanisms of ablation. However, concerning the two polymer samples, apart from considering the same theoretical ablation model, it is conceived that the photomehanical specifications of PMMA are involved in the ablation parameters. The threshold fluence for an ablation rate of 30 laser shots were obtained as 12.4, 24.64, and 11.71 J cm^(-2), for aluminum, silicon rubber and polymethylmethacrylate(PMMA) respectively.The ablation rate is exponentially decreased by the laser-shot number, especially for aluminum.Furthermore, the etch depth after 30 laser shots was measured as 180, 630 and 870 μm, for aluminum, silicon rubber and PMMA, respectively.
文摘Polymethylmethacrylate(PMMA) bone cement technology has progressed from industrial Plexiglass administration in the 1950 s to the recent advent of nanoparticle additives. Additives have been trialed to address problems with modern bone cements such as the loosening of prosthesis, high post-operative infection rates, and inflammatory reduction in interface integrity. This review aims to assess current additives used in PMMA bone cements and offer an insight regarding future directions for this biomaterial. Low index(< 15%) vitamin E and low index(< 5 g) antibiotic impregnated additives significantly address infection and inflammatory problems, with only modest reductions in mechanical strength. Chitosan(15% w/w PMMA) and silver(1% w/w PMMA) nanoparticles have strong antibacterial activity with no significant reduction in mechanical strength. Future work on PMMA bone cements should focus on trialing combinations of these additives as this may enhance favourable properties.
文摘Polymethylmethacrylate (PMMA) coated microcapsules of diclofenac sodium (DFS) were prepared by a modified wa-ter-in-oil-in-water (W1/O/W2) emulsion solvent evaporation method using sodium alginate (SAL) as a matrix material in the internal aqueous phase (W1).Their performance with respect to controlled release of the drug in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were evaluated, and compared with non-matrix microcapsules prepared by the conventional W1/O/W2 emulsion solvent evaporation method. Scanning electron micrographs (SEM) revealed that all the microcapsules were discrete and spherical in shape;however, the surface porosity of the matrix microcap-sules appeared to be less than that of the non-matrix microcapsules. In case of non-matrix microcapsules, an increase in the volume of water in W1 phase resulted in decrease in the drug entrapment efficiency (DEE) along with increase in release of the drug in both SGF and SIF. While in case of matrix microcapsules increase in the amount of SAL in W1 phase and concentration of the coating polymer in organic phase led to increase in DEE of the matrix microcapsules and considerable decrease in the drug release in both SGF and SIF. No interaction between the drug and any of the polymers used to prepare microcapsules was evident from Fourier transform infra-red (FTIR) analysis. The matrix microcapsules prepared using higher concentration of SAL and PMMA released the drug following zero order or Case-II transport model. The matrix microcapsules appeared to be suitable for releasing lesser amounts of DFS in SGF and providing extended release in SIF.
基金This work is supported by the National Key Projects for Fundamental Research,"Macromolecular Condensed State",the State Science and Technology Commission of China
文摘PMMA films in the high global chain orientation and nearly random segmental orientation(GOLR) state were prepared by uni-axially drawing at temperatures 20～30℃ above its glass transitiontempefature, T_g, and their isotropic and anisotropic properties were studied. Experimental results show thatthis kind of amorphous state, the GOLR state, is nearly isotropic in optical birefringence, IR-dichroism andX-ray diffraction patterns, but is very anisotropic in behaviors of thermal expansion, solvent-swelling andstress-strain.
文摘Introduction: To investigate a long-term in vivo deterioration of polymethylmethacrylate (PMMA) bone cement over time, we evaluated retrieved PMMA cement in terms of chemical elements presenting in the cement using energy dispersive analysis of X-rays;Knoop hardness;and the Young’s modulus using scanning acoustic microscopy. Materials and Methods: For mechanical evaluation, we could neglect the influences of entrapped air bubbles or blood by the use of small specimens. The study was based on thirteen cement samples (six used in the acetabulum and seven in the femur) derived from eight patients (age at revision surgery: mean 72.5, range 68 to 79). All of these samples were Simplex-P?cement. They were functioning well at least ten years after the previous surgery. Duration until revision surgery was ranged 12 to 25 years (average, 17.4 years). The reason for revision was aseptic mechanical loosening. Twenty samples of Simplex-Preg;cement were served by manually mixing as a control. Results: The average of the hardness of the cement was 17.0 ± 1.2 (range, 13.4-20.6). In the control, the hardness was 17.8 ± 1.5 (range, 14.0-24.6). There was no significant difference between these values. The mean of Young’s modulus of the cement was 5.61 ± 0.19 GPa (range, 5.09-6.10). In the control, the modulus was 6.04 ± 0.13 GPa (range, 5.68-6.45). Although the modulus was significantly less than that of the control, there was only 7% decrease in average between twelve and twenty-five years in vivo. Conclusions: Our results suggest that long-term implantation and functional loading in vivo may not be the limiting factor in the mechanical integrity of the bone cement.
文摘Polymethylmethacrylate (PMMA) is highly regarded for its transparency, and is used in such products as cameras and Video Tape Recorders as plastic lenses to take advantage of its excellent optical properties. Also, it is used in numerous other industrial fields like automobile lamp lenses, billboards, and lighting equipment. The phenomenon of environmental stress cracking is known to occur in PMMA due to ethanol, and there are cases when this may become a factor which causes damage of molded products. In the present paper, upon close observation by using the method of chemiluminescence in order to elucidate the mechanism by which this environmental stress cracking occurs, we report that we are able to capture the formation of a radical at the moment of cracking.
文摘Chemical modifications by incorporating organic dye molecules in polymethylmethacrylate (PMMA) matrix may open up the possibility of the development of smart materials. In the present work, Kiton red-620 laser dye is embedded in synthesized PMMA matrix by chemical doping process. The spectral investigations of Kiton red-620 doped PMMA matrix has been carried out using FTIR, UV-visible and photoluminescence spectrophotometers. FTIR study showed that the absorption band region 1800 - 1000 cm-1 becomes sharper with the concentration of dye in PMMA matrix. UV-visible and photoluminescence study showed that a slight shifting appears in the absorption spectra, emission spec- tra and intensity of emission peaks as concentration of dye increases in PMMA matrix.
文摘The solid-state medium containing pyrromethene 567 (PM567) in a polymethylmethacrylate polymer host is shown to lase under the flash lamp excitation.The experimental setup is an ordinary industrial product without special design.The bulk transmission losses,the output energy,and the other lasing properties are compared.The medium with the lowest transmission loss,measured to be 0.392 %/cm at 633 nm,gives a laser output of 130 mJ with a slope efficiency of 0.082%.
文摘We report a rare complication of diffuse alveolar hemorrhage and respiratory failure following percutaneous vertebroplasty in a patient who has evidence of cement leakage. Cement injection was done two days prior to presentation and covered 2 vertebral levels for osteoporosis induced fractures.
