Accelerated ripening in chemically fueled emulsions

Chemically fueled emulsions are solutions with droplets made of phase-separated molecules that are activated and deactivated by a chemical reaction cycle. These emulsions play a crucial role in biology as a class of membrane-less organelles. Moreover, theoretical studies show that droplets in these emulsions can evolve to the same size or spontaneously self-divide when fuel is abundant. All of these exciting properties, i. e., emergence, decay, collective behavior, and self-division, are pivotal to the functioning of life. However, these theoretical predictions lack experimental systems to test them quantitively. Here, we describe the synthesis of synthetic emulsions formed by a fuel-driven chemical cycle, and we find a surprising new behavior, i. e., the dynamics of droplet growth is regulated by the kinetics of the fuel-driven reaction cycle. Consequently, the average volume of these droplets grows orders of magnitude faster compared to Ostwald ripening. Combining experiments and theory, we elucidate the underlying mechanism

Development of TiNbTaZrMo bio-high entropy alloy (BioHEA) super-solid solution by selective laser melting, and its improved mechanical property and biocompatibility

BioHEAs, specifically designed high entropy alloy (HEA) systems for biomedical applications, represent a new era for biometals. However, recent challenges are (1) the poor shape customizability, and (2) the inevitable severe segregation due to the intrinsic fact that HEA is an ultra-multicomponent alloy system. To achieve shape customization and suppression of elemental segregation simultaneously, we used an extremely high cooling rate (~107 K/s) of the selective laser melting (SLM) process. We, for the first time, developed pre-alloyed Ti1.4Nb0.6Ta0.6Zr1.4Mo0.6 BioHEA powders and SLM-built parts with low porosity, customizable shape, excellent yield stress, and good biocompatibility. The SLM-built specimens showed drastically suppressed elemental segregation compared to the cast counterpart, representing realization of a super-solid solution. As a result, the 0.2% proof stress reached 1690 ± 78 MPa, which is significantly higher than that of cast Ti1.4Nb0.6Ta0.6Zr1.4Mo0.6 (1140 MPa). The SLM-built Ti1.4Nb0.6Ta0.6Zr1.4Mo0.6 BioHEA is promising as a next-generation metallic material for biomedical applications.Ishimoto T., Ozasa R., Nakano K., et al. Development of TiNbTaZrMo bio-high entropy alloy (BioHEA) super-solid solution by selective laser melting, and its improved mechanical property and biocompatibility. Scripta Materialia, 194, 113658. https://doi.org/10.1016/j.scriptamat.2020.113658

Novel single crystalline-like non-equiatomic TiZrHfNbTaMo bio-high entropy alloy (BioHEA) developed by laser powder bed fusion

This study developed a non-equiatomic Ti28.33Zr28.33Hf28.33Nb6.74Ta6.74Mo1.55 super-solid solutionized BioHEA using laser powder bed fusion (LPBF) to reach the full potential as BioHEA. We succeeded in significant suppression of elemental segregation, thus, resulting in a single crystalline-like texture by activating layer-to-layer epitaxial growth. Relatively low Young’s modulus was achieved in the single crystalline-like BioHEA. Moreover, LPBF-fabricated BioHEA exhibited significantly higher yield stress (1355–1426 MPa) due to the effective solid solution hardening compared to as-cast counterpart with marked segregation (949 MPa), and good biocompatibility. This is first report achieving BioHEA with low modulus, excellent strength-ductility balance, and good biocompatibility via LPBF.Gokcekaya O., Ishimoto T., Nishikawa Y., et al. Novel single crystalline-like non-equiatomic TiZrHfNbTaMo bio-high entropy alloy (BioHEA) developed by laser powder bed fusion. Materials Research Letters 11, 274 (2023); https://doi.org/10.1080/21663831.2022.2147406

Methodik

Die vegetationskundliche und strukturelle Zuordnung der Lebensraumtypen erfolgt nach der vorrangig von Braun-Blanquet entwickelten Vegetationsklassifizierung, einer hierarchischen Gliederung der Vegetationstypen (Syntaxonomie), die die Ebenen der Assoziation, des Verbandes, der Ordnung und der Klasse umfasst. Hierbei ist die Assoziation die grundlegende Einheit, in der die Pflanzengesellschaften zusammengefasst werden, die sich durch gleiche charakteristische Arten(gruppen)kombinationen auszeichnen. Der Verband vereinigt ähnliche Assoziationen. Das sind bereits umfassendere, jedoch standörtlich noch recht einheitliche Vegetationseinheiten. In Ordnungen werden ähnliche Verbände zusammengefasst. Die Klasse vereinigt ähnliche Ordnungen

Laser beam powder bed fusion of novel biomedical titanium/niobium/tantalum alloys: Powder synthesis, microstructure evolution and mechanical properties

The synthesis of spherical titanium/niobium/tantalum (TNT) alloy powders, namely Ti-20Nb-6Ta, Ti-27Nb-6Ta, Ti-35Nb-6Ta, and Ti-22Nb-19Ta (in wt-%) by electrode induction melting gas atomization is reported. The powder materials are characterized in detail using X-ray diffraction and scanning electron microscopy. Their processability via laser beam powder bed fusion (PBF-LB/M) is proven, and microstructure as well as mechanical properties of the additively manufactured specimens are assessed. All powders feature a dendrite-type microstructure with Nb/Ta-rich dendritic and Ti-rich inter-dendritic phases. Crystal structures of the powders are strongly composition-dependent. Nb- and Ta-rich Ti-35Nb-6Ta and Ti-22Nb-19Ta feature a body-centered cubic lattice, whereas Ti-rich Ti-20Nb-6Ta and Ti-27Nb-6Ta powders are characterized by multi-phase microstructures, consisting of non-equilibrium martensitic phases. Processing by PBF-LB/M causes significant changes in their microstructures: the dendrite-type morphologies vanish, and the formation of microstructures with a homogeneous element distribution can be observed in all additively manufactured parts. Ultimate tensile strength (UTS) as well as elongation at fracture are assessed by tensile testing. UTS values are found to be in a range from 651 MPa (Ti-35Nb-6Ta) to 802 MPa (Ti-20Nb-6Ta); strain-to-failure is between 21.3 % (Ti-35Nb-6Ta) and 31.7 % (Ti-22Nb-19Ta). Ductile fracture behavior is seen for all TNT alloys investigated

Kinetic Control over Droplet Ripening in Fuel-Driven Active Emulsions

Active droplets are made of phase-separated molecules that are activated and deactivated by a metabolic reaction cycle. Such droplets play a crucial role in biology as a class of membrane-less organelles. Moreover, theoretical studies show that active droplets can evolve to the same size or spontaneously self-divide when energy is abundant. All of these exciting properties, i.e., emergence, decay, collective behavior, and self-division, are pivotal to the functioning of life. However, these theoretical predictions lack experimental systems to test them quantitively. Here, we describe the synthesis of synthetic active droplets driven by a metabolic chemical cycle and we find a surprising new behavior, i.e., the dynamics of droplet-growth is regulated by the kinetics of the fuel-driven reaction cycle. Consequently, these droplets ripen orders of magnitude faster compared to Ostwald ripening. Combining experiments and theory, we elucidate the underlying mechanism, which could help better understand how cells regulate the growth of membrane-less organelles.<br /