Search results for "PEEK"
showing 10 items of 25 documents
Amorphous and crystalline polyetheretherketone: Mechanical properties and tissue reactions during a 3-year follow-up.
2007
The study was aimed to test the mechanical strength, structural stability, and tissue reactions of optically amorphous and crystalline polyetheretherketone (PEEK) plates during a 3-year follow-up in vivo and in vitro. The injection-moulded PEEK plates were implanted to the dorsal subcutis of 12 sheep, which were sacrificed at 6-156 weeks. Thereafter, the plates were subjected to tensile tests, and levels of crystallinity were assessed by differential scanning calorimetry (DSC). Histological evaluation was carried out using the paraffin technique. In vitro properties were examined with the tensile test and DSC at 0-156 weeks. Tissue reactions were mild and fairly similar for the amorphous an…
Soft Tissue Healing at One-Piece Zirconia Implants Compared to Titanium and PEEK Implants of Identical Design: A Histomorphometric Study in the Dog
2013
This study aimed to histomorphometrically evaluate the soft tissue reactions of one-piece zirconia implants versus titanium implants in regard to their insertion depth. Four one-piece implants of identical geometry were inserted on each side of six mongrel dogs: an uncoated zirconia implant, a zirconia implant coated with a calcium liberating titanium oxide, a titanium implant, and an experimental implant made of a synthetic material. Using a split-mouth design, they were inserted in both submerged and nonsubmerged healing modes. After 4 months, dissected blocks were stained with toluidine blue to histologically assess the marginal portion of the implant mucosa, apical extension of the barr…
Ultra-short ion-exchange columns for fast charge variants analysis of therapeutic proteins
2021
Abstract The purpose of this work was to study the potential of recently developed ultra-short column hardware for ion exchange chromatography (IEX). Various prototype and commercial columns having lengths of 5, 10, 15, 20 and 50 mm and packed with non-porous 3 µm particles were systematically compared. Both pH and salt gradient modes of elution were evaluated. Similarly, what has been previously reported for reversed phase liquid chromatography (RPLC) mode, an “on-off” retention mechanism was observed in IEX for therapeutic proteins and their fragments (25–150 kDa range). Because of the non-porous nature of the IEX packing material, the column porosity was relatively low (e = 0.42) and the…
Origin and correction of the deviations in retention times at increasing flow rate with Chromolith columns.
2010
Chromoliths can be used at flow rates beyond those feasible for conventional microparticulate packed columns. Ideally, the plots of the retention time versus the inverse of delivered flow rate should exhibit y-intercept of zero. However, significant positive deviations correlating with the solute polarity were observed for several compounds chromatographed with a Chromolith column, owing to the increased system pressure. Consequently, the dead time marker exhibits a smaller deviation, making the retention factors depend on the flow rate. Chromoliths are made of a silica-based monolith encapsulated within a PEEK tube, and should suffer larger stress with pressure than stainless steel columns…
Fixed lingual orthodontic retainer with bilateral missing lateral incisors produced in PEEK material using CAD/CAM technology
2021
Background The aim of this investigation is to evaluate the feasibility of digital workflow for lingual fixed retainer based on digital intraoral scan and appliance production from Polyetheretherketone (PEEK) material for clinical consideration. Material and methods Fully virtual lingual retainer with bilateral missing lateral incisors was designed using inlab software (Dentsply Sirona, Pennsylvania, USA). The designed retainer was produced in PEEK material and clinically adhered to lingual surfaces of the lower front teeth. Results Lingual retainer was successfully fabricated by full digital workflow and produced from PEEK material for clinical usage. Conclusions Although full digital work…
Peek polymer in orthodontics : a pilot study on children
2017
The purpose of the study has been making the orthodontic space maintainers in PEEK polymer (Polyetheretherketone) through a digital workflow. New digital technologies are taking hold in diagnosis, therapy and in dental laboratories. The digital world can help dentist in diagnosis and therapy: -diagnosis through the acquisition of radiographic images (CBCT) or scanners which allow the creation of 3D digital models - about therapy thanks to dental CAD CAM system. It consists of design devices through an dedicated software CAD and then realize devices through CAM system. We used digital system to improve the quality of the treatment and reduce costs. Peek polymer, subject of studies in recent …
Resource or waste? A perspective of plastics degradation in soil with a focus on end-of-life options.
2018
‘Capable-of-being-shaped’ synthetic compounds are prevailing today over horn, bone, leather, wood, stone, metal, glass, or ceramic in products that were previously left to natural materials. Plastic is, in fact, economical, simple, adaptable, and waterproof. Also, it is durable and resilient to natural degradation (although microbial species capable of degrading plastics do exist). In becoming a waste, plastic accumulation adversely affects ecosystems. The majority of plastic debris pollutes waters, accumulating in oceans. And, the behaviour and the quantity of plastic, which has become waste, are rather well documented in the water, in fact. This review collects existing information on pla…
Cross-linked PEEK-WC proton exchange membrane for fuel cell
2009
Abstract The low cost proton exchange membrane was prepared by cross-linking water soluble sulfonated-sulfinated poly(oxa- p -phenylene-3,3-phthalido- p -phenylene-oxa- p -phenylene-oxy-phenylene) (SsPEEK-WC). The prepared cross-linked membrane became insoluble in water, and exhibited high proton conductivity, 2.9 × 10 −2 S/cm at room temperature. The proton conductivity was comparable with that of Nafion ® 117 membrane (6.2 × 10 −2 S/cm). The methanol permeability of the cross-linked membrane was 1.6 × 10 −7 cm 2 /s, much lower than that of Nafion ® 117 membrane.
Sulfonētā poli(ēter ēter ketona) un modificētu illītu mālu minerālu kompozītu membrānu iegūšana un raksturošana
2017
SULFONĒTĀ POLI (ĒTER ĒTER KETONA) UN MODIFICĒTU ILLĪTU MĀLU MINERĀLU KOMPOZĪTU MEMBRĀNU IEGŪŠANA UN RAKSTUROŠANA. Ādiņa R., darba vadītāja Mg. Ķīm., pētniece Trubača-Boginska A. Bakalaura darbs, 40 lappuses, 20 attēli, 3 tabulas, 55 literatūras avoti, 7 pielikumi. Latviešu valodā. Darba teorētiskajā daļā apkopota informācija par degvielas šūnām, jonus vadošām membrānām, poli (ēter ēter ketonu), sulfonētu poli (ēter ēter ketonu), SPEEK kompozītiem, SPEEK mālu minerālu kompozītiem, kā arī māliem un mālu minerāliem, to struktūras tipiem, mālu minerālu attīrīšanu un aktivēšanu ar skābēm. Ar pulveru rentgendifraktometrijas, rentgenfluorescences spektrometrijas, diferenciāli termiskās un termogra…
Tritija caurspiešanās izvērtējums protonu vadošām membrānām
2022
TRITIJA CAURSPIEŠANĀS IZVĒRTĒJUMS PROTONU VADOŠĀM MEMBRĀNĀM. Kalniņa P., zinātniskie vadītāji: Mg.chem., pētn. Anete Stīne Teimane. Dr.chem., asoc. prof .Elīna Pajuste. Bakalaura darbs, 33 lappuses, 22 attēli, 5 tabulas, 33 literatūras avoti, 2 pielikumi. Latviešu valodā. Ūdeņradis viegli difundē, tāpēc nepieciešams novērtēt tā migrāciju un caurspiešanos materiālos, kas paredzēti izmantošanai ūdeņraža, tai skaitā tā radioaktīvā izotopa, tritija, vidē. Tas ir būtiski gan no ekonomiskā, gan no drošības viedokļa, jo saistās gan ar gāzes zudumiem, gan radioloģiskiem aspektiem tritija radioaktivitātes dēļ. Tritija caurlaidība ir atkarīga no materiāla īpašībām un no materiāla ekspluatācijas apstā…