Supelco

Poly(methyl methacrylate) analytical standard, for GPC, 50,000; CAS Number: 9011-14-7; Synonyms: PMMA,Poly(methacrylic acid methyl ester); Linear Formula: [CH2C(CH3)(CO2CH3)]n; find Supelco-81501 MSDS, related peer-reviewed papers, technical documents, similar products & more at Sigma-Aldrich

Poly(methyl methacrylate) analytical standard, for GPC, 50,000 9011-14-7

Poly(methyl methacrylate) analytical standard, for GPC, 50,000

Poly(methyl methacrylate)

Development and spectral characterization of poly (methyl methacrylate)/hydroxyapatite composite for biomedical applications

Drops of exosome dispersions from healthy epithelial colon cell line and colorectal cancer cells were dried on a superhydrophobic PMMA substrate. The residues were studied by small- and wide-angle X-ray scattering using both a synchrotron radiation micrometric beam and a high-flux table-top X-ray source. Structural differences between healthy and cancerous cells were detected in the lamellar lattices of the exosome macro-aggregates.

Superhydrophobic surfaces allow probing of exosome self organization using X-ray scattering.

Water-soluble polymers for the delivery of chemotherapeutic drugs passively target solid tumors as a consequence of reduced renal clearance and the enhanced permeation and retention (EPR) effect. Elimination of the polymers in the kidney occurs due to filtration through biological nanopores with a hydrodynamic diameter comparable to the polymer. Therefore we have investigated chemical features that may broadly be grouped as "molecular architecture" such as: molecular weight, chain flexibility, number of chain ends and branching, to learn how they impact polymer elimination. In this report we describe the synthesis of four pairs of similar molecular weight cyclic and linear polyacrylic acid polymers grafted with polyethylene glycol (23, 32, 65, 114 kDa) with low polydispersities using ATRP and "click" chemistry. The polymers were radiolabeled with (125)I and their pharmacokinetics and tissue distribution after intravenous injection were determined in normal and C26 adenocarcinoma tumored BALB/c mice. Cyclic polymers above the renal threshold of 30 kDa had a significantly longer elimination time (between 10 and 33% longer) than did the comparable linear polymer (for the 66 kDa cyclic polymer, t(1/2,beta)=35+/-2 h) and a greater area under the serum concentration versus time curve. This resulted in a greater tumor accumulation of the cyclic polymer than the linear polymer counterpart. Thus water-soluble cyclic comb polymers join a growing list of polymer topologies that show greatly extended circulation times compared to their linear counterparts and provide alternative polymer architecture for use as drug carriers.

The influence of polymer topology on pharmacokinetics: differences between cyclic and linear PEGylated poly(acrylic acid) comb polymers.

The literature is replete with articles arguing which is the next best restorative material to substitute porcelain fused to metal (PFM) crowns. Sadly, most of the discussion is about the strength and cost of the materials and often not about how--when properly used--some of these materials, combined with the appropriate techniques, can actually improve the quality of the dentistry we provide to our patients and make our restorative life easier and more predictable.

Anterior and posterior partial-coverage indirect restorations using supragingival dentistry techniques.

It was demonstrated that a thin film of chemically exfoliated graphene flakes, blended with poly(methyl methacrylate), could be used as a chemiresistor sensor for the sensitive and selective determination of formaldehyde vapor. Formaldehyde adsorption on the sensing film led to an increase in the electrical resistance of the sensing film. It was demonstrated that direct interaction of formaldehyde with graphene flakes was responsible for the observed response. Graphene/polymer ratio was found to be important parameter in defining the dominant sensing mechanism and sensor performance. A reasonable relationship was found between formaldehyde concentration and electrical resistance response of the sensor. The amounts of graphene and polymer in the sensing composite were optimized by using three-level full factorial design in order to acquire higher sensitivity and selectivity. Final sensor response for formaldehyde concentration was linear between 0.05 and 5.0 ppm. The detection limit of this sensing device was calculated equal to 10 ppb.

Graphene/poly(methyl methacrylate) chemiresistor sensor for formaldehyde odor sensing.

Biofilms on removable orthodontic appliances act as reservoir of microorganisms, capable of modifying the environmental condition of oral cavity and are difficult to be removed with routine hygiene measures. The present investigation includes enumeration, identification and numerical analysis of different types of cultivable bacteria associated with the biofilms on removable orthodontic appliances. Removable appliances of 25 healthy children among the ages of 10 to 14 years were taken to measure the prevalence of biofilms and type of microorganisms. For isolation of microorganism from biofilms different types of selective and non-selective medium based on standard methods were used. The data were further analysed by using Kolmogorov-Smirnov test, one-sample t-test and Spearman rank correlation coefficient. The percentage frequencies of isolates were also calculated The survey revealed the presence of both multi-species and mono species biofilms on appliances, with Non-Streptococci, anaerobic bacteria, Streptococcus spp., members of the family Enterobacteriaceae and Lactobacillus spp. as a dominant microbial flora of biofilms. Bacillus sp. and Candida sp. were isolated from one sample each. Significant positive and negative correlations were established among the species isolated from biofilms. Higher prevalence of the members of the family Enterobacteriaceae were reported during this study, advocating an extra hygienic measure is essential for this age group while wearing acrylic orthodontic appliances in oral cavity.

Biofilm associated microorganisms on removable oral orthodontic appliances in children in the mixed dentition.

In the treatment of vertebral compression fractures, vertebral body stenting with an expandable scaffold inserted before application of the bone cement was developed to impede secondary loss of vertebral height encountered in patients treated with balloon kyphoplasty. The purpose of this study was to clarify whether there are relevant differences between balloon kyphoplasty and vertebral body stenting with regard to perioperative and postoperative findings. In a two-armed randomized controlled trial, patients with a total of 100 fresh osteoporotic vertebral compression fractures were treated with either balloon kyphoplasty or vertebral body stenting. The primary outcome was the post-interventional change in the kyphotic angle on radiographs. The secondary outcomes were the maximum pressure of the balloon tamp during inflation, radiation exposure time, perioperative complications, and cement leakage. The mean reduction (and standard deviation) of kyphosis (the kyphotic correction angle) was 4.5° ± 3.6° after balloon kyphoplasty and 4.7° ± 4.2° after vertebral body stenting (p = 0.972). The mean pressures were 24 ± 5 bar (348 ± 72 pounds per square inch [psi]) during vertebral body stenting and 16 ± 6 bar (233 ± 81 psi) during balloon kyphoplasty (p = 0.014). There were no significant differences in radiation exposure time.None of the patients underwent revision surgery, and postoperative neurologic sequelae were not observed. Cement leakage occurred at twenty-five of the 100 vertebral levels without significant differences between the two intervention arms (p = 0.230). Intraoperative material-related complications were observed at one of the fifty vertebral levels in the balloon kyphoplasty group and at nine of the fifty levels in the vertebral body stenting group. No beneficial effect of vertebral body stenting over balloon kyphoplasty was found among patients with painful osteoporotic vertebral fractures with regard to kyphotic correction, cement leakage, radiation exposure time, or neurologic sequelae. Vertebral body stenting was associated with significantly higher pressures during balloon inflation and more material-related complications.

Vertebral body stenting versus kyphoplasty for the treatment of osteoporotic vertebral compression fractures: a randomized trial.

Polymethylmethacrylate-graphene (PMMA/RGO) nanocomposites were prepared via in situ bulk polymerization using two different preparation techniques. In the first approach, a mixture of graphite oxide (GO) and methylmethacrylate monomers (MMA) were polymerized using a bulk polymerization method with a free radical initiator. After the addition of the reducing agent hydrazine hydrate (HH), the product was reduced via microwave irradiation (MWI) to obtain R-(GO-PMMA) composites. In the second approach, a mixture of graphite sheets (RGO) and MMA monomers were polymerized using a bulk polymerization method with a free radical initiator to obtain RGO-(PMMA) composites. The composites were characterized by FTIR, (1)H-NMR and Raman spectroscopy and XRD, SEM, TEM, TGA and DSC. The results indicate that the composite obtained using the first approach, which involved MWI, had a better morphology and dispersion with enhanced thermal stability compared with the composites prepared without MWI.

Synthesis and characterization of the in situ bulk polymerization of PMMA containing graphene sheets using microwave irradiation.

Percutaneous sacroplasty is a procedure adapted from vertebroplasty, which is designed to ameliorate the painful morbidity associated with sacral insufficiency fractures without the invasiveness of open surgery. Early estimates of efficacy, according to several case reports and small series, appear promising, but the procedure is not without risk. Several cases of radiculopathy due to nerve root compression by extravasated polymethylmethacrylate (PMMA) have been reported. The authors present a case of radiculopathy caused by cement leakage from sacroplasty, treated with surgical decompression of the compromised nerve root. The patient presented with left S-1 radiculopathy and was found on CT to have a left S-1 nerve root completely encased in PMMA over a portion of its length. The patient underwent sacral laminectomy with the removal of PMMA and experienced pain relief and the return of function postoperatively. Surgical removal of PMMA extravasated during sacroplasty is feasible and should be considered when nerve root compression or canal stenosis causes pain or neurological deficit refractory to conservative therapy.

Sacral radiculopathy due to cement leakage from percutaneous sacroplasty, successfully treated with surgical decompression.

Simcoe cannula as an anterior chamber maintainer for intraocular lens implantation.

We evaluated the impact of pre-coating the tibial component with polymethylmethacrylate (PMMA) on implant survival in a cohort of 16 548 primary NexGen total knee replacements (TKRs) in 14 113 patients. In 13 835 TKRs a pre-coated tray was used while in 2713 TKRs the non-pre-coated version of the same tray was used. All the TKRs were performed between 2001 and 2009 and were cemented. TKRs implanted with a pre-coated tibial component had a lower cumulative survival than those with a non-pre-coated tibial component (p = 0.01). After adjusting for diagnosis, age, gender, body mass index, American Society of Anesthesiologists grade, femoral coupling design, surgeon volume and hospital volume, pre-coating was an independent risk factor for all-cause aseptic revision (hazard ratio 2.75, p = 0.006). Revision for aseptic loosening was uncommon for both pre-coated and non-pre-coated trays (rates of 0.12% and 0%, respectively). Pre-coating with PMMA does not appear to be protective of revision for this tibial tray design at short-term follow-up.

Does pre-coating total knee tibial implants affect the risk of aseptic revision?

To compare the push-out bond strength of a new glass fiber root canal filling material to that of Resilon/ Epiphany, EndoREZ, and gutta-percha/AH Plus root canal filling materials. Sixty roots were randomly divided into four groups (n = 15) according to the obturation material: group 1, Resilon/Epiphany (RE) (Pentron Clinical Technologies); group 2, gutta-percha/AH Plus (GP) (Dentsply DeTrey); group 3, EndoREZ obturation system (ER) (Ultradent); and group 4, glass fiber root canal filling (GF) (Stick Tech) and dual-curing resin sealer (MetaSeal, Parkell). Two-mm-thick horizontal sections from the coronal, middle, and apical thirds of each root were sliced for the push-out bond strength measurement. GF showed the significantly highest mean bond strength values at the coronal and middle thirds. At the apical third, GF showed significantly higher bond strength values than did RE and ER. However, there was no significant difference at the apical third between the GF and GP groups. The lowest bond strength values were recorded for ER. Glass fiber root canal filling material seems to provide promising bond strength to root canal dentin.

Push-out bond strength of a newly introduced glass fiber root canal filling material.

It is well-known that particles can be focused at mid-height of a micro-channel using Acoustic Radiation Force (ARF) tuned at the resonance frequency (h=λ/2). The resonance condition is a strong limitation to the use of acoustophoresis (particles manipulation using acoustic force) in many applications. In this study we show that it is possible to focus the particles anywhere along the height of a micro-channel just by varying the acoustic frequency, in contradiction with the resonance condition. This result has been thoroughly checked experimentally. The different physical properties as well as wall materials have been changed. The wall materials is finally the only critical parameters. One of the specificity of the micro-channel is the thickness of the carrier and reflector layer. A preliminary analysis of the experimental results suggests that the acoustic focusing beyond the classic resonance condition can be explained in the framework of the multilayered resonator proposed by Hill [1]. Nevertheless, further numerical studies are needed in order to confirm and fully understand how the acoustic pressure node can be moved over the entire height of the micro channel by varying the acoustic frequency. Despite some uncertainties about the origin of the phenomenon, it is robust and can be used for improved acoustic sorting or manipulation of particles or biological cells in confined set-ups.

Varying the agglomeration position of particles in a micro-channel using Acoustic Radiation Force beyond the resonance condition.

To assess the visual and refractive outcomes of implantation of intrastromal corneal ring segments (ICRS) in keratoconic eyes with no coincident topographic and comatic axes. Forty-one keratoconic eyes of 39 patients with no coincident topographic and comatic axes were implanted inferiorly with a Ferrara-type ICRS (Keraring SI6; Mediphacos Inc., Belo Horizonte, Brazil) of 150° of arc with a thickness of 150, 200, and 250 μm. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal coma-like root mean square, and residual refractive errors analyzed using vector analysis were recorded before and 6 months after the ICRS implantation. Mean UDVA was 0.76 ± 0.41 logMAR before and 0.53 ± 0.46 logMAR after surgery (P = .0006). CDVA was 0.13 ± 0.14 logMAR before and 0.07 ± 0.09 logMAR after surgery (P = .0007). Two eyes (4.9%) lost two lines or more of CDVA, 3 eyes (7.32%) lost one line, 16 eyes (39.02%) had no change in CDVA, 9 eyes (21.95%) gained one line, and 11 eyes (26.83%) gained two lines or more of CDVA. The safety index was 1.10. Spherical equivalent was significantly reduced after ICRS implantation (P < .001). Corneal coma-like root mean square changed from 0.80 ± 0.53 μm before surgery to 0.61 ± 0.59 μm after surgery (P = .02) for 4.5 mm of pupil size. One Ferrara-type ICRS of 150° of arc with a thickness of 150, 200, or 250 μm implanted inferiorly may reduce both astigmatism and corneal coma-like aberrations in keratoconic eyes with no coincident topographic and comatic axes, providing an improvement of UDVA and CDVA values.

Inferior intrastromal corneal ring segments in paracentral keratoconus with no coincident topographic and coma axis.

In the emergency department, patients undergoing lateral lumbar spine radiography examinations are positioned either lying on their side on an X-ray table with the X-ray beam vertical or lying supine on a trolley with the X-ray beam horizontal. The measured dose-area product (DAP) values were found to differ significantly, typically 1.3 Gy cm(2) for those patients examined on the X-ray table and 2.7 Gy cm(2) for those on a trolley. This work investigates the reason for higher DAP values with the horizontal beam technique. The UK's current recommended national diagnostic reference level (NDRL) for the lateral lumbar spine is 2.5 Gy cm(2). The measurements of body diameter on volunteers showed that rotating the patients from their side to their back resulted in an increase in tissue thickness of between 2 cm and 9 cm for the lumbar region. X-ray absorption increases exponentially with increasing tissue thickness. An increase of 5 cm in body diameter for a lateral lumbar spine at 93 kV will increase the DAP by more than two-fold. Mathematical modelling and measurements with polymethyl methacrylate provided data to predict the tube potential increase necessary to reduce the DAP. For the horizontal beam technique, the tube potential was increased from 93 kV to 102 kV and the average DAP reduced to 2.3 Gy cm(2). Radiographic technique should be understood when auditing the dose. Tube potential must be increased to optimise the horizontal beam technique. The 2.5-Gy cm(2) NDRL relates predominantly to the more common vertical beam technique. Separate local diagnostic reference levels for horizontal and vertical beam techniques are recommended.

Optimisation of patient dose for the horizontal beam technique in lateral lumbar spine radiographic examinations.

Right ventricular perforation and pulmonary embolism with polymethylmethacrylate cement after percutaneous kyphoplasty.

Prospective, parallel-group, controlled comparative randomized study. This study compares the efficacy in sagittal vertebral height and wedge deformity restoration, polymethylmethacrylate cement leakage safety, and functional outcome of balloon kyphoplasty (BK) versus KIVA (a novel vertebral augmentation technique) implant for the augmentation of fresh osteoporotic vertebral body fractures. Minimally invasive vertebral augmentation procedures have been widely used to treat vertebral compression fractures caused by osteoporosis. The results of these trials are encouraging in augmenting the vertebra and reducing the wedge deformity. However, after BK, polymethylmethacrylate leakage remains common after A3.1 AO type fractures, with a frequency per vertebra into the epidural space up to 9.8% but less common (0.03%-5.6%) in A1.1 AO type fracture. KIVA is a novel percutaneous uniportal vertebral augmentation device that is designed to restore the vertebral body and reduce polymethylmethacrylate leakage. From a total 190 patients with osteoporotic fractures who were initially enrolled in this prospective randomized study, 10 patients were excluded (5 met exclusion criteria, 5 with evidence of metastasis). This study examined 82 patients (69 ± 11 yr) with 133 fractures who received KIVA and 86 patients (72 ± 9 yr) with 122 fractures that were reinforced with BK. Anterior (anterior vertebral body height ratio [AVBHr]), midline (midline vertebral body height ratio [MVBHr]), and posterior (posterior vertebral body height ratio [PVBHr]) vertebral body height ratio and Gardner segmental vertebral wedge deformity were measured preoperatively to postoperatively. New fractures were recorded at the final observation. The baseline anthropometric and roentgenographic parameters did not differ between the 2 groups. Any cement leakage was examined on plain roentgenograms and computed tomographic scan. All patients were followed for an average of 14 months (range, 13-15 mo) postoperatively. RESULTS.: At the final observation, both KIVA and BK restored significantly AVBHr, PVBHr, and MVBHr. However, only KIVA device reduced significantly the Gardner angle (P = 0.002). Residual kyphosis of more than 5° was measured significantly more (P < 0.001) in the BK than in KIVA spines. KIVA showed significantly lower (3%, χ2, P ≤ 0.05) leakage) [corrected] (paravertebral, intradiscal) rate per vertebra than BK (0.098%) in which because of intracanal leakage 2 patients developed acute paraplegia and were reoperated in emergency. New fracture rate was similar in both groups. Back pain scores (visual analogue scale), 36-Item Short Form Health Survey (Physical Function and Mental Health domains), and Oswestry Disability Index scores improved significantly in the patients of both groups. Both KIVA and BK restored in short-term similarly vertebral body height, but only KIVA restored vertebral body wedge deformity. KIVA was followed by significantly lower and harmless always extracanal leakage rate than BK. Longer observation is needed to show whether these radiological changes have any functional impact.

Balloon kyphoplasty versus KIVA vertebral augmentation--comparison of 2 techniques for osteoporotic vertebral body fractures: a prospective randomized study.

Obtaining an accurate interocclusal record which relates the upper and lower jaws to one another is critical in the laboratory production of dental restorations. This may be particularly challenging when the configuration of missing teeth dictate that such records are dependent on the remaining mucosal tissues for support. This article presents a practical and time saving method of using implant healing abutments, located within an edentulous distal extension space, to serve as vertical stops for an interocclusal record.

A technique to create an interocclusal bite registration using in situ implant healing abutments.

Pleural infection 55 years after plombage for pulmonary tuberculosis.

The authors endeavor to highlight the surgical management of severe neurological deficit resulting from cement leakage after percutaneous vertebroplasty and to systematically review the literature on the management of this complication. A patient presented after a vertebroplasty procedure for traumatic injury. A CT scan showed polymethylmethacrylate leakage into the right foramina at T-11 and L-1 and associated central stenosis at L-1. He underwent decompression and fusion for removal of cement and stabilization of the fracture segment. In the authors' systematic review, they searched Medline, Scopus, and Cochrane databases to determine the overall number of reported cases of neurological deficit after cement leakage, and they collected data on symptom onset, clinical presentation, surgical management, and outcome. After surgery, despite neurological recovery postoperatively, the patient developed pneumonia and died 16 days after surgery. The literature review showed 21 cases of cement extravasation with neurological deficit. Ultimately, 15 patients had resolution of the postoperative deficit, 5 had limited change in neurological status, and 2 had no improvement. Cement augmentation procedures are relatively safe, but certain precautions should be taken to avoid such complications including high-resolution biplanar fluoroscopy, considering the use of a local anesthetic, and controlling the location of cement spread in relationship to the posterior vertebral body. Immediate surgical intervention with removal of cement provides good results with complete recovery in most cases.

Poly(methyl methacrylate)

analytical standard, for GPC, 50,000

Propriedades

Nível de qualidade

grau

temperatura de autoignição

prazo de validade

peso molecular

technique(s)

solubilidade

densidade

M_w/M_n

formato

temperatura de armazenamento

InChI

InChI key

Descrição

Descrição geral

Informações de segurança

Código de classe de armazenamento

WGK

Equipamento de proteção individual

Documentação

Certificado de análise

Certificado de origem

Mais documentos

Cotações e pedidos

Artigos revisados por pares

Assistência Técnica

Poly(methyl methacrylate)

analytical standard, for GPC, 50,000

Propriedades

Nível de qualidade

grau

temperatura de autoignição

prazo de validade

peso molecular

technique(s)

solubilidade

densidade

Mw/Mn

formato

temperatura de armazenamento

InChI

InChI key

Descrição

Descrição geral

Informações de segurança

Código de classe de armazenamento

WGK

Equipamento de proteção individual

Documentação

Certificado de análise

Certificado de origem

Mais documentos

Cotações e pedidos

Artigos revisados por pares

Assistência Técnica

M_w/M_n