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Proceedings of the Royal Society of... Oct 1970
Topics: Humans; Polyvinyls; Protective Clothing; Radiation Protection; Ventilators, Mechanical
PubMed: 5274210
DOI: No ID Found -
Journal of Oral Science Oct 2022This study investigates the attenuation of radiation doses by four materials, heat-polymerized, and self-polymerized polymethyl methacrylate (PMMA), putty-type, and...
PURPOSE
This study investigates the attenuation of radiation doses by four materials, heat-polymerized, and self-polymerized polymethyl methacrylate (PMMA), putty-type, and injection-type polyvinyl siloxane (PVS) impression material. This in vitro study should aid in the selection of dental materials for radiotherapy prostheses, thereby minimizing the possibility of radiotherapy side effects.
METHODS
Specimens of each type were fabricated as a 5 × 5 cm squares with a thickness of 10 mm. Heat-polymerizing PMMA, self-polymerizing PMMA, putty-type PVS impression material, and injection-type PVS impression material were selected. A calibration curve was created to determine the association of radiation doses and grayscale value. A linear accelerator was used to irradiate the specimens. The radiation doses above and below the materials were measured using radiochromic film dosimetry. After film irradiation, the pixel scale of color change was used to determine the radiation dose based on the created calibration curve. The results were exported to find average doses to calculate the percentage of the attenuated dose for a comparison of the four materials.
RESULTS
The average attenuated doses of heat-polymerizing PMMA, self-polymerizing PMMA, putty-type PVS, and injection-type PVS were 10.8%, 6.2%, 17.2%, and 14.2% respectively.
CONCLUSION
PVS showed higher attenuating radiation exposure compared with PMMA.
Topics: Dental Implants; Dental Impression Materials; Polymethyl Methacrylate; Polyvinyls; Siloxanes
PubMed: 36070925
DOI: 10.2334/josnusd.22-0167 -
European Journal of Vascular and... Jun 2016Endoleak remains the Achilles heel of endovascular aneurysm repair and the exclusion of Type II endoleaks, in particular, remains challenging. This systematic review... (Review)
Review
OBJECTIVE
Endoleak remains the Achilles heel of endovascular aneurysm repair and the exclusion of Type II endoleaks, in particular, remains challenging. This systematic review presents the evidence for ethylene-vinyl-alcohol-copolymer liquid embolic agent as a monotherapy in the treatment of endoleaks.
METHODS
A systematic literature search was performed for all studies reporting the use of liquid embolic agent as a sole agent in the treatment of endoleaks. Patient numbers, clinical details (endoleak type, route of delivery) and outcome in terms of survival, technical and clinical success with freedom from endoleak together with follow-up period were examined.
RESULTS
Only 12 articles reporting the use of liquid embolic as the sole treatment modality for endoleaks in 174 patients were identified. All but 21 patients had a Type II endoleak. Transarterial embolization was attempted in 73% of patients with 48 patients having direct sac puncture. Technical success was high at 96%, but in patients with adequate imaging, the clinical success rate dropped to 79%. Complications were sparsely reported and follow-up ranged from 0 to 75 months.
CONCLUSIONS
This review highlights the lack of data regarding the use of liquid embolic agent as a monotherapy with only 4 studies including more than 10 patients. Data from the largest series suggests a learning curve exists and no study reports on cost effectiveness. Technical success does not always translate into clinical success and with the largest series only reporting median 4-month follow-up no claims regarding durability can be made. In problematic Type II endoleaks, however, liquid embolic agent is a welcome addition to the treatment armamentarium.
Topics: Aortic Aneurysm, Abdominal; Endoleak; Endovascular Procedures; Humans; Polyvinyls; Treatment Outcome
PubMed: 27040505
DOI: 10.1016/j.ejvs.2016.02.015 -
Molecules (Basel, Switzerland) Dec 2022To satisfy the ever-increasing energy demands, it is of the utmost importance to develop electrochemical materials capable of producing and storing energy in a highly...
To satisfy the ever-increasing energy demands, it is of the utmost importance to develop electrochemical materials capable of producing and storing energy in a highly efficient manner. Titanium dioxide (TiO) has recently emerged as a promising choice in this field due to its non-toxicity, low cost, and eco-friendliness, in addition to its porosity, large surface area, good mechanical strength, and remarkable transport properties. Here, we present titanium dioxide nanoplates/polyvinylidene fluoride (TiO/PVDF) membranes prepared by a straightforward hydrothermal strategy and vacuum filtration process. The as-synthesized TiO/PVDF membrane was applied for energy storage applications. The fabricated TiO/PVDF membrane served as the negative electrode for supercapacitors (SCs). The electrochemical properties of a TiO/PVDF membrane were explored in an aqueous 6 M KOH electrolyte that exhibited good energy storage performance. Precisely, the TiO/PVDF membrane delivered a high specific capacitance of 283.74 F/g at 1 A/g and maintained capacitance retention of 91% after 8000 cycles. Thanks to the synergistic effect of TiO and PVDF, the TiO/PVDF membrane provided superior electrochemical performance as an electrode for a supercapacitor. These superior properties will likely be used in next-generation energy storage technologies.
Topics: Polyvinyls; Titanium; Water
PubMed: 36615478
DOI: 10.3390/molecules28010285 -
Environmental Health Perspectives Oct 1981Poly(vinyl chloride) resins are produced by four basic processes: suspension, emulsion, bulk and solution polymerization. PVC suspensions resins are usually relatively...
Poly(vinyl chloride) resins are produced by four basic processes: suspension, emulsion, bulk and solution polymerization. PVC suspensions resins are usually relatively dust-free and granular with varying degrees of particle porosity. PVC emulsion resins are small particle powders containing very little free monomer. Bulk PVC resins are similar to suspension PVC resins, though the particles tend to be more porous. Solution PVC resins are smaller in particle size than suspension PVC with high porosity particles containing essentially no free monomer. The variety of PVC resin products does not lend itself to broad generalizations concerning health hazards. In studying occupational hazards the particular PVC process and the product must be considered and identified in the study.
Topics: Chemical Industry; Humans; Particle Size; Polyvinyl Chloride; Polyvinyls; Risk; Vinyl Chloride
PubMed: 7333230
DOI: 10.1289/ehp.8141123 -
The FEBS Journal Oct 2011In the 1990s, a technique was developed to transfer proteins from electrophoresis gels onto poly(vinylidene difluoride) (PVDF) membranes, digest the proteins on the... (Review)
Review
In the 1990s, a technique was developed to transfer proteins from electrophoresis gels onto poly(vinylidene difluoride) (PVDF) membranes, digest the proteins on the membranes with proteases such as trypsin and analyze the resulting peptides on the membranes directly by mass spectrometry to identify the proteins. This technique, based on gel electrophoresis, is particularly useful for analyzing protein isoforms, splicing variants and post-translationally modified proteins. Previously, the low ionization efficiency of peptides immobilized on the membranes often rendered this technique useless. However, this technique has been improved by the use of PVDF membranes with a small pore size, which has enabled highly efficient and effective electroblotting and mass spectrometric analyses. Here, the advantage of this technique is discussed.
Topics: Combinatorial Chemistry Techniques; Electrophoresis, Polyacrylamide Gel; Mass Spectrometry; Peptides; Polyvinyls; Porosity; Proteins
PubMed: 21848805
DOI: 10.1111/j.1742-4658.2011.08303.x -
STAR Protocols Mar 2022Mixed-matrix membranes (MMMs) comprising polymer matrices and metal-organic frameworks (MOFs) provide efficient and economic CO separation. One major challenge is to...
Mixed-matrix membranes (MMMs) comprising polymer matrices and metal-organic frameworks (MOFs) provide efficient and economic CO separation. One major challenge is to construct continuous and defect-free MMMs due to poor MOF/polymer compatibility. Here, this protocol describes the step-by-step details for synthesis of desired linkers that allow the fabrication of new polymerizable MOFs containing vinyl groups (BUCT MOFs) and the preparation procedures of defect-free MMMs with enhanced MOF/polymer interfacial adhesion and boosted gas separation performances. For complete details on the use and execution of this profile, please refer to Chen et al. (2021).
Topics: Metal-Organic Frameworks; Polymers; Polyvinyl Chloride
PubMed: 35059652
DOI: 10.1016/j.xpro.2021.101039 -
Proceedings of the National Academy of... Jul 2013Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to...
Reading out the temperature-memory of polymers, which is their ability to remember the temperature where they were deformed recently, is thus far unavoidably linked to erasing this memory effect. Here temperature-memory polymer actuators (TMPAs) based on cross-linked copolymer networks exhibiting a broad melting temperature range (ΔT(m)) are presented, which are capable of a long-term temperature-memory enabling more than 250 cyclic thermally controlled actuations with almost constant performance. The characteristic actuation temperatures T(act)s of TMPAs can be adjusted by a purely physical process, guiding a directed crystallization in a temperature range of up to 40 °C by variation of the parameter T(sep) in a nearly linear correlation. The temperature T(sep) divides ΔT(m) into an upper T(m) range (T > T(sep)) forming a reshapeable actuation geometry that determines the skeleton and a lower T(m) range (T < T(sep)) that enables the temperature-controlled bidirectional actuation by crystallization-induced elongation and melting-induced contraction. The macroscopic bidirectional shape changes in TMPAs could be correlated with changes in the nanostructure of the crystallizable domains as a result of in situ X-ray investigations. Potential applications of TMPAs include heat engines with adjustable rotation rate and active building facades with self-regulating sun protectors.
Topics: Hot Temperature; Polyethylenes; Polyvinyls
PubMed: 23836673
DOI: 10.1073/pnas.1301895110 -
Biomacromolecules Sep 2015Heparin is a highly sulfated polysaccharide and is useful because of its diverse biological functions. However, because of batch-to-batch variability and other factors,...
Heparin is a highly sulfated polysaccharide and is useful because of its diverse biological functions. However, because of batch-to-batch variability and other factors, there is significant interest in preparing biomimetics of heparin. To identify polymeric heparin mimetics, a cell-based screening assay was developed in cells that express fibroblast growth factor receptors (FGFRs) but not heparan sulfate proteoglycans. Various sulfated and sulfonated polymers were screened, and poly(vinyl sulfonate) (pVS) was identified as the strongest heparin-mimicking polymer in its ability to enhance binding of basic fibroblast growth factor (bFGF) to FGFR. The results were confirmed by an ELISA-based receptor-binding assay. Different molecular weights of pVS polymer were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers were able to facilitate dimerization of FGFRs leading to cell proliferation in FGFR-expressing cells, and no size dependence was observed. The data showed that pVS is comparable to heparin in these assays. In addition, pVS was not cytotoxic to fibroblast cells up to at least 1 mg/mL. Together this data indicates that pVS should be explored further as a replacement for heparin.
Topics: Biomimetic Materials; Cell Proliferation; Cells, Cultured; Fibroblast Growth Factor 2; Heparin; Humans; Polyvinyls; Sulfonic Acids
PubMed: 26212474
DOI: 10.1021/acs.biomac.5b00557 -
International Journal of Pharmaceutics Oct 2022This study investigated the ability of in situ amorphisation using microwave irradiation in order to prepare highly supersaturated ASDs, i.e. ASDs with drug loads higher...
This study investigated the ability of in situ amorphisation using microwave irradiation in order to prepare highly supersaturated ASDs, i.e. ASDs with drug loads higher than the saturation solubility in the polymer at ambient temperature. For this purpose, compacts containing the crystalline drug celecoxib (CCX) and polyvinylpyrrolidone (PVP), polyvinylpyrrolidone-vinyl acetate copolymer (PVP/VA), or polyvinyl acetate (PVAc), were prepared at drug loads between 30 and 90 % w/w. Sodium dihydrogen phosphate (NaHPO) monohydrate was included in all compacts, as a source of water, to facilitate the dielectric heating of the compacts upon dehydration during microwave irradiation. After processing, the samples were analysed towards their solid state using X-ray powder diffraction (XRPD) and modulated differential scanning calorimetry (mDSC). Complete amorphisation of CCX was achieved across all the investigated polymers and with a maximal drug load of 90, 80, and 50 % w/w in PVP, PVP/VA, and PVAc, respectively. These drug loads corresponded to a 2.3-, 2.4-, and 10.0-fold supersaturation in the investigated polymers at ambient temperature. However, dissolution experiments with the in situ prepared ASDs in fasted state simulated intestinal fluid (FaSSIF), showed a lower initial drug release (0-2 h) compared to equivalent physical mixtures of crystalline CCX and polymers or crystalline CCX alone. The lower drug release rate was explained by the fusion of individual drug and polymer particles during microwave irradiation and, subsequently, a lack of disintegration of the monolithic ASDs. Nevertheless, supersaturation of CCX in FaSSIF was achieved with the in situ amorphised ASDs with PVP and PVP/VA, albeit only after 3-24 h. Overall, the present study confirmed that it is feasible to prepare supersaturated ASDs in situ. However, in the current experimental setup, the monolithic nature of the resulting ASDs is considered a limiting factor in the practical applicability of this preparation method, due to limited disintegration and the associated negative effect on the drug release.
Topics: Celecoxib; Microwaves; Polymers; Polyvinyls; Povidone; Solubility; Water
PubMed: 35985526
DOI: 10.1016/j.ijpharm.2022.122115