Post treatment preparation of hybrid metal halide perovskite nanocrystal-embedded polymethylmethacrylate blends with enhanced stablity

Hybrid organic-inorganic perovskites have been the subject of recent intense interest due to advances in photovoltaic and other optoelectronic applications. However, their poor stability limits commercial market application We enhance water stability by post treatment preparation of hybrid metal halide perovskite nanocrystal-embedded polymethylmethacrylate （PM- MA） blend films. Through blending process without any cleaning of nanocrystals, crystalline hybrid organic-inorganic perovs-kite nanocrystals were incorporated into PMMA matrix with well-dispersion Passivation of PMMA on the surface of the per-ovskite nanocrystals results in decreased traps and a long photoluminescence （PL） lifetime despite the bromine vacancies in the crystal lattice. Moreover, such color purity and inherent high transmittance for fluorescence emission of perovskite nanocrystals will endow the films with promising potentials in diverse practice photonic applications.

Polymethylmethacrylate bone cements and additives: A review of the literature

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.

Polymethylmethacrylate Coated Alginate Matrix Microcapsules for Controlled Release of Diclofenac Sodium

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.

POLYMETHYLMETHACRYLATE FILMS IN THE STATE OF HIGH GLOBAL CHAIN ORIENTATION BUT NEARLY RANDOM SEGMENTAL ORIENTATION

PMMA films in the high global chain orientation and nearly random segmental orientation (GOLR) state were prepared by uni-axially drawing at temperatures 20 similar to 30 degrees C above its glass transition temperature, T-g, and their isotropic and anisotropic properties were studied. Experimental results show that this kind of amorphous state, the GOLR state, is nearly isotropic in optical birefringence, IR-dichroism and X-ray diffraction patterns, but is very anisotropic in behaviors of thermal expansion, solvent-swelling and stress-strain.

Characteristics of xenon-lamp pumped pyrromethene 567-doped dye laser based on polymethylmethacrylater

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%.

Biodegradation of Polymethylmethacrylate Bone Cement May Not Be a Serious Issue in Total Hip Arthroplasty—Retrieval Study for Knoop Hardness and Young’s Modulus

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.

Observation of Environmental Stress Cracking in Polymethylmethacrylate by Using the Chemiluminescence Method

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.

Alveolar Hemorrhage and Acute Respiratory Distress Syndrome Associated with Pulmonary Cement Following Percutaneous Vertebroplasty with Polymethylmethacrylate

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.

A visco-elastoplastic constitutive model of aircraft polymethylmethacrylate related to strain rate and temperature

The visco-elastoplastic mechanical behavior related to the applied strain rate and temperature around the glass transition temperature of Polymethylmethacrylate(PMMA)has been systematically investigated.The uniaxial tensile test was performed at strain rate and temperature rangs 1.0×10^(-4)-1.0×10^(-2)s^(-1)and 363-393 K,respectively,and the Dynamic Mechanical Analysis(DMA)test was carried out between 363 K and 413 K at various frequencies.Moreover,the robust complex constitutive model considering the temperature and strain rate effect is proposed.A nonlinear viscoelastic model is established to describe the viscoelastic response on the basis of the Zhu-Wang-Tang(ZWT)model and the time temperature equivalence principle,including the dependence of strain rate and temperature.Considering the yield stress,the cooperative model is adopted.The viscoplastic mechanical response is manifested as the competition performance of the softening deformation and hardening behavior.The predicted mechanical responses maintain good consistency with the experimental results,indicating that the visco-elastoplastic constitutive model proposed can accurately predict the mechanical behavior of PMMA materials within the imposed strain rate and near the glass transition temperature range.

Long-term results and radiographic findings of percutanous vertebroplasties with polymethylmethacrylate for vertebral osteoporotic fractures

Background Percutaneous vertebroplasty （PVP） has become a popular procedure for painful vertebral osteoporotic fracture （VOF）, with immediate pain relief and improved mobility; however, polymethylmethacrylate （PMMA） injected into the vertebral body is not absorbable and little information is available concerning the long-term results. In this retrospective study, we evaluated the long-term clinical results and radiological changes after PVPs for VOFs. Methods Fifty-one patients with VOFs were treated by PVPs with PMMA between 2000 and 2004. After 〉7 years of follow-up, eight patients had died from causes unrelated to the intervention and 12 patients were lost to follow-up, thus leaving 31 patients available for evaluation with an average length of follow-up of 9.2 years （follow-up rate, 72.1%）. Among these 31 patients, the PMMA was injected at 43 levels with a mean volume of 4.3 ml per level （range, 2-6 ml）. The pain was assessed with a visual analog scale （VAS）, and the mobility was graded as walking without difficulty （grade 1）, walking with assistance （grade 2）, and bedridden （grade 3）. Plain radiographs and computed tomography （CT） were obtained and assessed pre-operatively, immediately post-operatively, and after 7 years of follow-up. The PMMA, vertebral height, and Cobb angle were assessed and compared. Results All of the patients experienced pain relief and improved mobility after intervention and during the follow-up period. Cement leakage was detected in post-operative CT scans in 9 of 51 patients, but without neurological compromise. For the 31 patients followed up over 7 years, the VAS decreased from 8.3±2.6 pre-operatively, to 2.1±1.6 immediately post-operatively, and 1.0±0.9 at the final follow-up evaluation, with significantly improved mobility. Additional compression fractures occurred at adjacent levels in three patients, and there were no new fractures at the augmented vertebrae. Based on a review of the radiographs, neither loose nor displaced cement was detected. The changes in vertebral height and Cobb angle were not significant. On CT scans, the cement closely contacted or infiltrated the trabecular bone. The boundary between the cement and trabecular bone was indistinct and there was no evident radiolucent gap between the cement and trabecular bone. Conclusions At an average follow-up of 9.2 years, PVPs provided sustained pain relief and improved mobility in patients with VOFs. The PMMA injected into the vertebral body combined closely with the host trabecular bone without adverse reactions.

Dual-functional porous and cisplatin-loaded polymethylmethacrylate cement for reconstruction of load-bearing bone defect kills bone tumor cells

Malignant bone tumors are usually treated by resection of tumor tissue followed by filling of the bone defect with bone graft substitutes.Polymethylmethacrylate(PMMA)cement is the most commonly used bone substitute in clinical orthopedics in view of its reliability.However,the dense nature of PMMA renders this biomaterial unsuitable for local delivery of chemotherapeutic drugs to limit the recurrence of bone tumors.Here,we introduce porosity into PMMA cement by adding carboxymethylcellulose(CMC)to facilitate such local delivery of chemotherapeutic drugs,while retaining sufficient mechanical properties for bone reconstruction in load-bearing sites.Our results show that the mechanical strength of PMMA-based cements gradually decreases with increasing CMC content.Upon incorporation of≥3%CMC,the PMMA-based cements released up to 18%of the loaded cisplatin,in contrast to cements containing lower amounts of CMC which only released less than 2%of the cisplatin over 28 days.This release of cisplatin efficiently killed osteosarcoma cells in vitro and the fraction of dead cells increased to 91.3%at day 7,which confirms the retained chemotherapeutic activity of released cisplatin from these PMMA-based cements.Additionally,tibias filled with PMMA-based cements containing up to 3%of CMC exhibit comparable compressive strengths as compared to intact tibias.In conclusion,we demonstrate that PMMA cements can be rendered therapeutically active by introducing porosity using CMC to allow for release of cisplatin without compromising mechanical properties beyond critical levels.As such,these data suggest that our dual-functional PMMA-based cements represent a viable treatment option for filling bone defects after bone tumor resection in load-bearing sites.

Synthesis and Characterization of a Polymeric Material Blended to Bone Forming Elements

A synthetizing material blended with two distinct proteins (collagen and casein) and mineral mixture, was developed in order to evaluate their properties suitable for possible applications in the biomedical such as inducing the regeneration of damaged bone, either due to an accident or illness. Samples were evaluated by 1) Mechanical properties tests under the bending, 2) Scanning electronic microscopy and 3) Infrared spectroscopy were carried out. The results showed that the developed material has breaking strength and structure characteristics associated with the protein used in their composition. This fact suggests that the used protein determines the resistance of the material, in such a way according to the required use, being able to choose appropriate strength and duration either short or long time. The material composition for specific use, in order to find the most suitable mixture for bone replacement, or induce bone recovery, according to the required properties similar to those of damaged living tissue.

Effect of Air Plasma Processing on the Adsorption Behaviour of Bovine Serum Albumin on Spin-Coated PMMA Surfaces

This paper reports the adsorption of Bovine Serum Albumin （BSA） onto Dielectric Barrier Discharge （DBD） processed Poly（methyl methacrylate） （PMMA） surfaces by a Quartz Crystal Microbalance with Dissipation monitoring （QCM-D） technique. The purpose is to study the influence of DBD processing on the nature and scale of BSA adsorption on PMMA surface in vitro. It was observed that DBD processing improves the surface wettability of PMMA film, a fact attributable to the changes in surface chemistry and topography. Exposure of the PMMA to Phosphate Buffed Saline （PBS） solution in the QCM-D system resulted in surface adsorption which reaches an equilibrium after about 30 minutes for pristine PMMA, and 90 minutes for processed PMMA surface. Subsequent injection of BSA in PBS indicated that the protein is immediately adsorbed onto the PMMA surface. It was revealed that adsorption behaviour of BSA on pristine PMMA differs from that on processed PMMA surface. A slower adsorption kinetics was observed for pristine PMMA surface, whilst a quick adsorption kinetics for processed PMMA. Moreover, the dissipation shift of protein adsorption suggested that BSA forms a more rigid structure on pristine PMMA surface that on processed surface. These data suggest that changes in wettability and attendant chemical properties and surface texture of the PMMA surface may play a significant role in BSA adsorption process.

Role of fast-setting cements in arthroplasty: A comparative analysis of characteristics

AIM To evaluate the behaviour of two fast-setting polymethylmethacrylate(PMMA) cements CMW~? 2 G and Palacos~? fast R + G, as reference: Standard-setting Palacos~? R + G.METHODS The fast-setting cements CMW~? 2 G and Palacos~? fast R + G were studied, using standard-setting high viscosity Palacos~? R + G as a reference. Eleven units(of two batch numbers) of each cement were tested. All cements were mixed as specified by the manufacturer and analysed on the following parameters: Handling properties(mixing, waiting, working and hardening phase) according to Kuehn, Mechanical properties according to ISO 5833 and DIN 53435, Fatigue strength according to ISO 16402, Benzoyl Peroxide(BPO)-Content by titration, powder/liquid-ratio by weighing, antibiotic elution profile by High Performance Liquid Chromatography. All tests were done in an acclimatised laboratory with temperatures set at 23.5 ℃± 0.5 ℃ and a humidity of > 40%. RESULTS Palacos~? fast R + G showed slightly shorter handling properties(doughing, hardening phase, n = 12) than CMW~? 2 G, allowing to reduce operative time and to optimise cemented cup implantation. Data of the quasistatic properties of ISO 5833 and DIN 53435 of both cements tested was comparable. The ISO compressive strength(MPa) of Palacos~? fast R + G was significantly higher than CMW~? 2 G, resulting in ANOVA(P < 0.01) and two sample t-test(P < 0.01) at 0.05 level of significance(n = 20). Palacos~? fast R + G showed a higher fatigue strength of about 18% mean(ISO 16402) of 15.3 MPa instead of 13.0 MPa for CMW~? 2 G(n = 5 × 10~6 cycles). Palacos~? fast R + G and CMW~? 2 G differed only by 0.11%(n = 6) with the former having the higher content. The BPO-content of both cements were therefore comparable. CMW~? 2 G had a powder/liquid ratio of 2:1, Palacos~? fast R + G of 2.550:1 due to a higher powder content. Despite its higher gentamicin content, CMW~? 2 G showed a significantly lower antibiotic elution over time than Palacos~? fast R + G(n = 3). CONCLUSION Both cements are compliant with international standards and are highly suitable for their specified surgical indications, affording a time-saving measure without detriment to the mechanical properties.

HOT EMBOSSING METHODS FOR PLASTIC MICROCHANNEL FABRICATION

Fabrication of microchannels on polymethylmethacrylate （PMMA） substrates using novel microfabrication methods is demonstrated. The image of microchannels is transferred from a silicon master possessing the inverse image of the microchannel to a PMMA plate by using hot embossing methods. The silicon master is electrostatically bonded to a Pyrex 7740 glass wafer, which improves the device yield from about 20 devices to hundreds of devices per master. Effects of embossing temperature, pressure and time on the accuracy of replication are systematically studied using the orthogonal factorial design. According to the suggested experimental model, the time for the whole embossing procedure is shorten from about 20 min to 6 min, and the accuracy of replication is 99.3%. The reproducibility of the hot embossing method is evaluated using 10 channels on different microfluidic devices, with variations of 1.4 % in depth and 1.8% in width.

Adjacent Level Vertebral Fractures in Patients Operated with Percutaneous Vertebroplasty

Percutaneous vertebroplasty is a minimally invasive procedure that involves filling of a fractured vertebral body with bone cement to relieve pain and to restore the vertebral height. It is a safe and effective treatment and is widely used for treating Osteoporotic Vertebral Compression Fracture. Despite of its beneficial advantages over primary conservative managements, adjacent level vertebral compression fracture remains the challenge for surgeons. Adjacent level vertebral compression fracture following percutaneous vertebroplasty using PMMA cement has been reported as a complication. Numerous risk factors have been reported for the occurrence of new adjacent VCFs after PVP. The multiple level osteoporotic vertebral compression fractures and the increasing age of the patients are directly proportional to the risk of developing new symptomatic adjacent vertebral compression fracture after PVP. Moreover, low BMD and cement leakage are other factors that directly affect the incidence of new symptomatic adjacent vertebral fractures. The aim of this review is to evaluate the adjacent level vertebral compression fracture following percutaneous vertebroplasty on the basis of radiographs, Kaplan-Meier Estimation index and also the factors that lead to adjacent level vertebral compression fractures.

MORPHOLOGICAL OBSERVATION OF SINGLE-CHAIN POLY (METHYL METHACRYLATE) PARTICLES

Tapping mode atomic force microscope has been applied to observe single-chain PMMA particles which were stored for six months at room temperature after sprayed hom very dilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Monodisperse PMMA standards of molecular weights ranging from 7.90 x 10(4) to 1.3 x 10(6) were used to investigate the effect of molecular weight on the size of the single-chain PMMA particles. These single-chain particles showed close to spherical shapes. The morphology of single-chain PMMA particles of a given molecular weight was found to be identical in spite of different solvents used for solution spraying. Molecular weight dependence of the particle dimension was also found. The diameters of single-chain PMMA particles after correction of tip-geometry effect were compared to the values estimated from molecular weight and density.

Dynamic Shear Stress Measurements of PMMA

In this paper,experiments of one-dimensional plane plate impact on polymethylmethacrylate（PMMA） targets are conducted,in which dynamic transverse stresses induced in the targets are measured using a new type of manganin piezoresistive stress gauge having 50 Ω low-pressure narrow grid-like foil.It is shown that this new instrument can improve measurement accuracy remarkably by reducing the so-called strain effect.Moreover,relationship between shear stress and longitudinal stress within a certain range of the latter is obtained.

Ponceau 2R Doped Poly (ST/MMA) as Fluorescent Solar Collectors and Evaluation Effect of Matrix on Their Field Performance

Luminescent solar concentrators (LSCs) with styrene (ST) and methylmethacrylate (MMA) of different percentage as the matrix were prepared by a casting method using ponceau 2R. DSC has been used to compare the thermal stability of the different LSCs. FTIR spectroscopy shows that appearance of -N=N- for ponceau 2R in all ST/MMA matrixes indicating that the highest stability of this kind of dye in these matrixes. The values of the optical band gap (Eg) have been obtained from direct allowed transition before and after the samples have been exposed to sunlight for 9 weeks. Photodegradation studies revealed that the more photostable dye doped in PMMA matrix than in other matrixes. The results showed that the homo PMMA/ponceau 2R system has the highest fluorescence quantum yield (Qf). Therefore this sample can be selected for field performance of fluorescent solar collectors. The photovoltaic cell coupled with homo PMMA/2R LSC shows a maximum efficiency, 2% compared to the normal one.