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[en] Percutaneous vertebroplasty has gained widespread popularity and demonstrated clinical efficacy in the treatment of spinal osteoporotic compression fractures and pathologic osteolytic lesions. Despite its rapid pain relief and safety, this minimally invasive intervention has exhibited some rare complications over the past decade. In this case study, we describe a patient with an uncommon complication of polymethylmethacrylate (PMMA) cement pulmonary embolism following fluoroscopy-guided percutaneous vertebroplasty for treatment of pain associated with an osteoporotic vertebral fracture. We present this case to highlight that vertebroplasty is not risk-free and that knowledge of such potentially severe complication is necessary for prevention and optimal operative outcomes
[en] Primary intraosseous arteriovenous malformations are rare. Many minimally invasive procedures can be considered preoperative steps and/or definitive treatment. The case reported regards a young woman with a voluminous arteriovenous extratroncular infiltrating malformation of the humerus. She underwent several treatments, but none of them was completely occlusive. The last treatment consisted of direct percutaneous puncture of the intraosseous alteration and injection of polymethylmethacrylate (PMMA), which is normally used in percutaneous vertebroplasty. We obtained complete occlusion of the humerus lytic lesion. To the best of our knowledge, this represents the first case of intraosseous AVM treated by percutaneous injection of PMMA.
[en] We describe a lateral transiliac direct puncture approach to the SI vertebral body for polymethylmethacrylate (PMMA) cernentoplasty of painful metastatic lesions. This approach was performed using a 15-cm-long trocar needle with 3-mm outer diameter, introduced under general anesthesia and fluoroscopic control. A lateral projection was used to center the needle just in front of the spinal canal and subjacent to the superior plate of the S1 vertebral body. Needle progression was controlled using anteroposterior and lateral fluoroscopic projections alternately with a needle course parallel to an axial plane, avoiding conflict with the S1 foramen. After needle tip placement in the center of the S1 vertebral body, diluted PMMA with a setting time of 8 min was delivered. Ipsilateral lesions of the lateral sacral compartment were filled with the same needle by stepwise withdrawal and continuous PMMA injection.
[en] In this paper, the second harmonic of Nd:YAG laser was used for the fabrication of microchannels (microholes) in polymethylmethacrylate. It was found that irradiation parameters as well as focusing lens focal length have significant effect on the geometry of the microchannels; while, the quality of the channels is dominantly affected by the focusing lens focal length. Our results also show that the maximum accessible depth is increased with sample movement in drilling direction at an appropriate velocity. (paper)
[en] Early studies of the simultaneous effect of a tensile stress and radiation were focused on natural fibers such as silk and cotton, but were extended to some common synthetic polymers. In all cases, a significant increase in the creep rate and decrease in the time to failure (lifetime) were observed. In this work, the authors have examined the effect of γ irradiation and tensile loading on PMMA. The approach has consisted of determining the stress effects on kinetics of chemical degradation. Knowing that under γ rays, PMMA undergoes an almost pure random chain scission, the aim was to demonstrate that a tensile stress influences the rate of radiolytic chain scission. Experimentally, the authors have tried to establish the stress effects on the yield of chain scission
[en] A ripples structure is observed in the photoluminescence (PL) spectra of MoS2 adsorbed on the surface of single polymethyl methacrylate (PMMA) microspheres in contrast to the broad spectra of nanosheets. Theoretical simulations and photonic nanojet technique have been used to identify the ripple structures. Part of these structures has been found to be due to the whispering gallery modes (WGMs) of the microcavity. The Raman modes of MoS2 and PMMA, on the other hand, are identified by the photonic nanojet induced enhancement. This work helps applications in photonics and sensing technique which require clean systems with well characterized spectral lines.
[en] Since 1987, experiments have been performed comparing covering materials compared were PMMA, PVC and FRP. Trials were carried out in tunnels in order to verify the effects of plastic rigid covering materials on transparency to PAR and tomato production. The results of 1992, 1993 and 1994 are reported in this paper. PMMA sheets showed the highest level of transmittance whereas FRP sheets the lowest one. The effects inherent to the different optical properties of the compared sheets had great influence on both quantitative and qualitative characters of tomato production
[it]La Sperimentazione, in Atto dal 1987 ha Previsto il confronto di coperture realizzate con lastre ondulate di PMMA, grecate di PVC e ondulate di PRFV. Nel corso delle dimostrare have been valutati Gli Effetti esercitati da Tali coperture su ALCUNI Parametri Climatici Che caratterizzano l'ambiente-serra è sulla Produzione di ortive e specie da fiore reciso. In this nota vengono riferiti i Risultati ottenuti nel triennio 1992-1994, pomodoro sul. Al di sotto delle lastre di PMMA si e 'costantemente riscontrato il piu' ELEVATO Livello di Radiazione fitosintenticamente Attiva (PAR): MENTRE Quello piu 'Ridotto e' riferibile alle lastre di PRFV. A Una maggiore disponibilita, per le piante, di Radiazione fotosinteticamente Attiva, e' sempre corrisposto ONU Incremento ponderale della prodzione del pomodoro
[en] Room-temperature ultrasonic compressional wave velocity and attenuation measurements have been carried out on commercial poly-methyl methacrylate (PMMA) and fully deuterated PMMA. Deuteration was found to reduce the velocity by 4.4 ± 1.2% which can be completely accounted for by the density change of 8.0%, assuming no changes in atomic force constants or molar volume. The attenuation was 17% higher in the deuterated sample. Making reasonable assumptions about the distribution function for the relaxation times of molecular groupings moving in two-well potentials, the attenuation increase is attributed to a reduction in the attempt frequency for barrier hopping of main chain and/or ester methyl groups. (author)
[en] Basic research on nanoelectronics is often limited by the high cost and large-scale methods to fabricate electrodes with controlled gap size in nanometer scales. Here nanoelectrodes with a controlled gap size of sub-100 nm were fabricated by modified nanoimprint lithography (NIL) via a double-layer lift-off process utilizing polymethylmethacrylate (PMMA) and polydimethylglutarimide (PMGI) as the lift-off resist. Firstly the patterns of the electrode mold were transferred onto the upper PMMA layer by NIL techniques and then through controlling the developing time and concentration of developer of the PMGI under layer, regulating the exact gap size of the transferred metal nanoelectrode. The result indicated that the ‘undercut’ phenomenon was observed of the PMGI transfer layer during the developing process; through controlling the feature size of the undercut length, the gap size of the transferred metal nanoelectrode was precisely controlled, which showed shrinkage behavior. The nanoelectrodes with gap sizes of 800, 400, 200, and 100 nm can be reduced to about 440, 120, 80, and 70 nm. Our result provides a low-cost and large-scale route to prepare nanoelectrodes with controlled gap size, which can be valuable for current efforts in nanoelectronics. (paper)