Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-53097 Zeitschriftenartikel Qu, R.; Maaß, Robert; Liu, Z.; Tönnies, D.; Tian, L.; Ritchie, R.; Zhang, Z.; Volkert, A. Flaw-insentive fracture of a micrometer-sized brittle metallic glass Brittle materials, such as oxide glasses, are usually very sensitive to flaws, giving rise to a macroscopic fracture strength that is much lower than that predicted by theory. The same applies to metallic glasses (MGs), with the important difference that these glasses can exhibit certain plastic strain prior to catas- trophic failure. Here we consider the strongest metallic alloy known, a ternary Co 55 Ta 10 B 35 MG. We show that this macroscopically brittle glass is flaw-insensitive at the micrometer scale. This discovery emerges when testing pre-cracked specimens with self-similar geometries, where the fracture stress does not de- crease with increasing pre-crack size. The fracture toughness of this ultra-strong glassy alloy is further shown to increase with increasing sample size. Both these findings deviate from our classical under- standing of fracture mechanics, and are attributed to a transition from toughness-controlled to strength- controlled fracture below a critical sample size. Elsevier Ltd. 2021 Acta Materialia 218 10.1016/j.actamat.2021.117219 2021-08-16 OPUS4-37080 Zeitschriftenartikel Liu, J.-Y.; Hou, X.-N.; Tian, Y.; Jiang, L.; Deng, S.; Röder, B.; Ermilov, Eugeny Photoinduced energy and charge transfer in a bis(triphenylamine)-BODIPY-C60 artificial photosynthetic system Triphenylamines (TPAs), boron dipyrromethenes (BODIPYs) and fullerenes C60 are excellent building blocks for the design of artificial photosynthetic systems. In the present work, we report the synthesis, characterization and detailed photophysical studies of a novel (TPA)2-BODIPY-C60 tetrad in polar and nonpolar solvents. The absorption spectrum of this compound covered virtually the entire visible Region (350-700 nm) and could be interpreted as a superposition of the spectra of individual components. Upon TPA-part excitation, a fast and very efficient excitation energy transfer (EET) delivers the excitation to the BODIPY moiety resulting in complete quenching of the TPA first excited singlet state as well as the appearance of the BODIPY fluorescence. The efficiency of EET process was estimated to be 1. Direct or indirect (via EET) excitation of the BODIPY-part of the tetrad is followed by photoinduced charge transfer to the charge-separated state BODIPY+-C60- irrespective of the solvent used. In polar N,N-dimethylformamide (DMF)charge recombination occurs directly to the ground state with the Charge recombination rate, kCR, slower than 108 s-1, whereas in nonpolar toluene (TOL) a small energy gap between the charge-separated state and first excited singlet state of the BODIPY moiety facilitates the back charge transfer process. The latter results in the appearance of thermally activated delayed fluorescence. The rate of charge separation was found to be ca. 2 times faster in TOL than in DMF. 2016 RSC Advances 6 62 57293 57305 10.1039/c6ra06841c 2016-08-08 OPUS4-50491 Zeitschriftenartikel Xu, F.; Ren, H.; Zheng, M.; Shao, X.; Dai, T.; Wu, Y.; Tian, L.; Liu, Y.; Liu, B.; Günster, Jens; Liu, Y.; Liu, Y. Development of biodegradable bioactive glass ceramics by DLP printed containing EPCs/BMSCs for bone tissue engineering of rabbit mandible defects Bioactive glass ceramics have excellent biocompatibility and osteoconductivity; and can form direct chemical bonds with human bones; thus, these ceramic are considered as "Smart" materials. In this study, we develop a new type of bioactive glass ceramic (AP40mod) as a scaffold containing Endothelial progenitor cells (EPCs) and Mesenchymal stem cells (BMSCs) to repair critical-sized bone defects in rabbit mandibles. For in vitro experiments: AP40mod was prepared by Dgital light processing (DLP) system and the optimal ratio of EPCs/BMSCs was screened by analyzing cell proliferation and ALP activity, as well as the influence of genes related to osteogenesis and angiogenesis by direct inoculation into scaffolds. The scaffold showed suitable mechanical properties, with a Bending strength 52.7 MPa and a good biological activity. Additionally, when EPCs/BMSCs ratio were combined at a ratio of 2:1 with AP40mod, the ALP activity, osteogenesis and angiogenesis were significantly increased. For in vivo experiments: application of AP40mod/EPCs/BMSCs (after 7 days of in vitro spin culture) to repair and reconstruct critical-sized mandible defect in rabbit showed that all scaffolds were successfully accurately implanted into the defect area. As revealed by macroscopically and CT at the end of 9 months, defects in the AP40mod/EPCs/BMSCs group were nearly completely covered by normal bone and the degradation rate was 29.9% compared to 20.1% in the AP40mod group by the 3D reconstruction. As revealed by HE and Masson staining analyses, newly formed blood vessels, bone marrow and collagen maturity were significantly increased in the AP40mod/EPCs/BMSCs group compared to those in the AP40mod group. We directly inoculated cells on the novel material to screen for the best inoculation ratio. It is concluded that the AP40mod combination of EPCs/BMSCs is a promising approach for repairing and reconstructing large load bearing bone defect. Elsevier Ltd. 2020 Journal of the Mechanical Behavior of Biomedical Materials 103 103532 103532 10.1016/j.jmbbm.2019.103532 2020-03-05 OPUS4-39783 Zeitschriftenartikel Sun, C.; Tian, X.; Wang, L.; Liu, Y.; Wirth, Cynthia; Günster, Jens; Li, D.; Jin, Z. Effect of particle size gradation on the performance of glass-ceramic 3D printing process Particle size gradation is regarded as an effective method for overcoming the contradicting requirements in three-dimensional printing (3DP). In present work, particle size gradation was optimized to obtain both acceptable flowability of the powder material and high-strength 3D-printed glass-ceramic products. The effect of gradation on the printing process, sintering process and performance of the 3D-printed glass-ceramic products was investigated comprehensively. The glass-ceramic powders with three size ranges were mixed in certain proportions and applied to print parts. The result showed parts printed with powder mixed by 60 wt% 45-100 µm and 40 wt% 0-25 µm particles had satisfactory density of 1.60 g/cm³ and bending strength of 13.8 MPa. The flowability decreased with an increasing proportion of fine particles. Part density was determined by the powder bulk density in the powder bed as well as the shrinkage during sintering while strength of part was found to be dependent on the sintering degree. Elsevier 2017 Ceramics International 43 1 578 584 10.1016/j.ceramint.2016.09.197 2017-04-11