polymer composite
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This review discusses the methods of the nanofabrication of metal-polymer composites, especially those based on silver nanostructures. The advantages of composites based on biocompatible polymer matrix, as well as their modifications with suitable techniques are broadly discussed. Different forms of silver nanostructures are reviewed with special emphasis on their antimicrobial activity. Mechanisms of the antimicrobial action of the silver nanostructures are summarized together with proposed ways of passing through the cell wall and processes triggered in cellular environment.
The main goal of this study is to develop a micromechanical model of a particle-filled dental composite focused on the residual stress (RS) field developed during the curing process in its microstructure. A finite element model of a representative volume element of filler and resin was developed, and volumetric shrinkage was simulated during the curing process. Four material models (von Mises plasticity model, Drucker-Prager plasticity model, von Mises plasticity model with stress relaxation and Drucker-Prager plasticity with stress relaxation) of the polymer resin were built to assess the influence of the material model on the resulting internal stress. The relationship between the curing process and the magnitude of the stress components will be described, and an analysis of the post-curing state of the material in particular microstructure locations will be conducted in this study. Obtained RS is comparable to the stresses developed in the material under the external load. The substantial dependence on the choice of material model for resin is to be observed, and the suitability of particular models is discussed.
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This study investigated the effect of peroxide bleaching gel on the durability of the adhesive bond between composite material, enamel, and dentin created with the etch-and-rinse adhesive Gluma Comfort Bond (GLU) and with the self-etch adhesives Clearfil SE Bond (CLE), Adper Prompt (ADP), and iBond (IBO). The adhesives were applied to flattened enamel and dentin of extracted human molars and built up with a microhybrid composite (Charisma). After 25 eight-hour cycles of bleaching with a 20% carbamide peroxide bleaching gel (Opalescence PF 20), the shear bond strength was measured and compared with one-day and two-month control specimens stored in water. The data were analyzed using nonparametric Mann-Whitney and Kruskal-Wallis statistics (p<0.05). Detailed fractographic analysis was performed using scanning electron microscopy. The bleaching gel significantly decreased the bond strength on both enamel and dentin for the simplified single-step self-etch adhesives ADP and IBO and markedly affected a fracture pattern of ADP specimens at the periphery of their bonded area. The results of our study indicate that the durability of adhesive restorations can be detrimentally influenced by carbamide peroxide bleaching and that different adhesives show varying sensitivity levels to the bleaching gel.
- MeSH
- bělení zubů metody MeSH
- bisfenol A-glycidyl methakrylát chemie MeSH
- časové faktory MeSH
- dentin ultrastruktura MeSH
- dentinová adheziva chemie MeSH
- látky na bělení zubů chemie MeSH
- leptání zubů kyselinou metody MeSH
- lidé MeSH
- mechanický stres MeSH
- mikroskopie elektronová rastrovací MeSH
- močovina analogy a deriváty chemie MeSH
- organofosfáty chemie MeSH
- peroxidy chemie MeSH
- pevnost ve smyku MeSH
- povrchové vlastnosti MeSH
- pryskyřičné cementy chemie MeSH
- složené pryskyřice chemie MeSH
- testování materiálů MeSH
- vazba zubní * MeSH
- voda chemie MeSH
- zubní materiály chemie MeSH
- zubní sklovina ultrastruktura MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- randomizované kontrolované studie MeSH
- srovnávací studie MeSH
Byly připraveny tenké filmy metodou odpařování vodných roztoků chitosanu nebo jeho směsís poloxamerem407, želatinou či polyvinylalkoholem. Filmy různé tloušťky byly síťovány fosfátovýmiionty. Obsahovaly mikronizovanou kyselinu listovou v koncentraci 9,1 % nebo 3,2 %. Byla sledovánaprolongovaná několikahodinová liberace kyseliny listové do isotonických fosfátových pufrů při pH5,5; 6,0 a 6,5. Mechanizmus liberace byl v počáteční fázi řízen převážně difúzí rozpuštěné frakce,při vyšších hodnotách pH se uplatnila vyšší rychlost rozpouštění látky. U některých kompozic bylaprokázána sorpce kyseliny listové na chitosan s rozsahem závislým na složení kompozitů a naaktuální aciditě média.
Thin films were prepared by the method of evaporation of aqueous solutions of chitosan or itsmixtures with poloxamer 407, gelatin, or polyvinyl alcohol. Films of varying thickness werecross-linked with phosphate ions. They contained micronized folic acid in a concentration of 9.1 %or 3.2 %. Prolonged several hours' liberation of folic acid into isotonic phosphate buffer at pH 5.5,6.0,and 6.5was examined. In the initial stage, the mechanism of liberationwas governed by diffusionof the dissolved fraction, at higher pH values a higher rate of dissolution of the substance played itsrole. In some composites, sorption of folic acid to chitosan in an extent dependent on the compositionof composites and current acidity of the medium was demonstrated.
- MeSH
- chitin analogy a deriváty metabolismus MeSH
- farmaceutická technologie MeSH
- finanční podpora výzkumu jako téma MeSH
- koncentrace vodíkových iontů MeSH
- kyselina listová chemie MeSH
- polymery farmakologie chemie terapeutické užití MeSH
- roztoky chemie terapeutické užití MeSH
- Publikační typ
- přehledy MeSH
- srovnávací studie MeSH
Polyaniline (PANI) belongs to a group of conducting polymers that show numerous properties useful in biomedical applications. Although PANI has long been studied in terms of interaction with human tissue, the published studies are mostly focused on composites of polyaniline with other polymers, not allowing for generalization of the obtained results. The present study is focused on the adhesion of human liver cells to a conducting and nonconducting polyaniline films. The ability of human liver cells to attach to both types of the tested surfaces was confirmed. Cell proliferation on the PANI surfaces was monitored in relation to material biocompatibility and to its practical applications. The results showed statistically significant differences in cell proliferation depending on the type of PANI film. The study thus points out the need to test materials in their neat forms, which allow for better generalization of the test results leading to their broader applications.
Periprosthetic bone loss in response to total hip arthroplasty is a serious complication compromising patient's life quality as it may cause the premature failure of the implant. Stress shielding as a result of an uneven load sharing between the hip implant and the bone is a key factor leading to bone density decrease. A number of composite hip implants have been designed so far to improve load sharing characteristics. However, they have rarely been investigated from the bone remodeling point of view to predict a long-term response. This is the first study that employed a mechano-biochemical model, which considers the coupling effect between mechanical loading and bone biochemistry, to investigate bone remodeling after composite hip implantation. In this study, periprosthetic bone remodeling in the presence of Carbon fiber polyamide 12 (CF/PA12), CoCrMo and Ti alloy implants was predicted and compared. Our findings revealed that the most significant periprosthetic bone loss in response to metallic implants occurs in Gruen zone 7 (-43% with CoCrMo; -35% with Ti) and 6 (-40% with CoCrMo; -29% with Ti), while zone 4 has the lowest bone density decrease with all three implants (-9%). Also, the results showed that in terms of bone remodeling, the composite hip implant is more advantageous over the metallic ones as it provides a more uniform density change across the bone and induces less stress shielding which consequently results in a lower post-operative bone loss (-9% with CF/PA12 implant compared to -27% and -21% with CoCrMo and Ti alloy implants, respectively).
- MeSH
- analýza metodou konečných prvků MeSH
- biologické modely * MeSH
- biomechanika MeSH
- biomimetické materiály škodlivé účinky MeSH
- kostní denzita účinky léků MeSH
- kyčelní kloub účinky léků fyziologie chirurgie MeSH
- kyčelní protézy škodlivé účinky MeSH
- mechanický stres * MeSH
- modul pružnosti účinky léků MeSH
- nylony škodlivé účinky chemie MeSH
- pooperační období MeSH
- remodelace kosti účinky léků MeSH
- slitiny škodlivé účinky MeSH
- uhlík chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
