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排序方式: 共有3750条查询结果,搜索用时 15 毫秒
991.
Süleyman Çağatay Dayan Emre Mumcu 《International Journal of Applied Ceramic Technology》2019,16(6):2467-2473
This in vitro study evaluated the microhardness and two-body wear of various computer-assisted design and computer-assisted manufacturing (CAD/CAM) resin-matrix ceramic materials stored in different storage media. For each material (Paradigm MZ100, Lava Ultimate, Vita Enamic, and Cerasmart), 40 disk-shaped specimens (8 mm diameter × 3 mm thickness) were prepared and divided into four subgroups (n = 10) according to storage material (artificial saliva, distilled water, 0.02 mol/L citric acid, 3:1 ethanol/water). Following storage at 37°C for 7 days, microhardness was measured with a Knoop test, and wear was measured using a 3D scanner and surface analysis program before and after loading on a chewing simulator (200 000 cycles). Wear values of Vita Enamic were lower in comparison to the other materials tested (P < 0.001). Storage media were found to have a significant effect on material microhardness (P < 0.001), but not on wear (P = 0.820). 相似文献
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Kuldeep Kumar Bansal Ezgi Özliseli Ari Rosling Jessica Marianne Rosenholm 《Advanced functional materials》2021,31(33):2101998
Instances of synthetic polymers obtained from renewable feedstock with the possibility of post-synthesis functionalization are scarce. Herein, the first ever synthesis and drug delivery application of amphiphilic block copolymer (mPEG-b-PJL) derived from renewable jasmine lactone with free allyl groups on the backbone is presented. The polymer is synthesized via facile ring-opening polymerization and subsequently, UV mediated thiol-ene click chemistry is utilized for post-functionalization. The introduction of hydroxyl, carboxyl, and amine functionality to mPEG-b-PJL polymer is successfully established. As a proof-of-concept demonstration, doxorubicin (DOX) is conjugated on hydroxyl-terminated polymer (mPEG-b-PJL-OH) via redox responsive disulfide linkage to obtain PJL-DOX. PJL-DOX is readily self-assembled into micelles with an average hydrodynamic size of ≈ 150 nm and demonstrates reduction-responsive DOX release. Micelles are evaluated in vitro for cytocompatibility and selective drug release in cancer cells (MDA-MB-231) using 10 mm glutathione as a reducing agent. Cytotoxicity and microscopy results confirm a redox-triggered release of DOX, which is further confirmed by flow cytometry. The introduction of these novel functional polymers can pave the way forward in designing polymer-drug conjugate-based smart nano-carriers. 相似文献
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This study investigated the corrosion behavior of cryogenically treated Ti6Al4V alloys in an isotonic solution. Samples were subjected to shallow or deep cryogenic treatment, and some samples then underwent an aging procedure. They were characterized by microstructural analysis, an open circuit potential test, an electrochemical impedance method, and a potentiodynamic test. The polarization tests demonstrated that the deep cryogenic treatment shifted the corrosion potential to more anodic values compared to the untreated sample. For all treated samples, it was found that the corrosion current densities were lower than those in the untreated sample, and the lowest current densities were registered for the sample subjected to deep cryogenic treatment for 36 hr. The shallow cryogenic treated samples and the sample aged without cryogenic treatment showed semicapacitive loops with poor corrosion impedance compared to the untreated sample, whereas deep cryogenic treatment produced Warburg impedance with diffusion in the solid phase. 相似文献
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Emre Çinar Serhat Koçyiğit Arda Aytimur İbrahim Uslu Ahmet Akdemir 《Metallurgical and Materials Transactions A》2014,45(9):3929-3937
In this study, the boron-doped barium-stabilized bismuth cobalt oxide thermoelectric nanocrystalline ceramic powders were produced by the polymeric precursor technique. The powders were characterized by X-ray diffraction, scanning electron microscopy, and the physical properties measurement system. The X-ray diffraction results showed that these patterns have mixture of two phases as face-centered cubic and body-centered cubic. Values of the crystallite size, the dislocation density, and the microstrain were calculated by the Scherrer equation. According to these values, the crystallite size decreased from 60 to 51 nm with the boron addition in the boron-undoped and boron-doped samples, respectively. The scanning electron microscope results showed that nanograins are rarely seen in the boron-undoped samples, but nanograins turn into needle-like and layered structures with boron addition. The diameters distribution of nanofibers was calculated. The average diameter of the boron-doped sample is smaller than the boron-undoped sample. The physical properties measurement system values showed that the electrical and thermal conductivity, the Seebeck coefficient, and the figure of merit increased with the temperature rise for both samples. The boron-doping effect increased the electrical and thermal conductivity, decreased the Seebeck coefficient, and decreased the figure of merit. 相似文献