An experimentally validated rod model for soft continuum robots

Soft robots are bio-inspired, highly deformable robots with the ability to interact with workpieces in a manner that complements their hard robot counterparts. To develop practical applications and reproducible designs of soft robots, new models are necessary to describe their kinematics and dynamics. In the present work, we describe experimental and numerical investigations of a popular pneumatically-actuated soft continuum arm. These works enable us to derive constitutive relations and develop a rod model for large deformations of the arm that faithfully describes its bending behavior. We show how the resulting non-classical constitutive relation can be defined either through experiments or through quasi-static finite element simulations. With the help of this relation, the resulting rod model can be used to study the dynamics of the soft robot arm in a fast and tractable manner. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of macrocyclic ligands incorporating sulfur and furan subunits

Abstract

Polyammonium macrocycles containing sulfur and furan units in the macrocyclic ring have been synthesized and studied for ATPase activity. The synthetic methodology involved using tosyl protection for the amines and the formation of macrocyclic Lactams, followed by reduction using borane in THF. Deprotection of the tosylated forms of the macrocycle was accomplished using sodium in butanol for the furan macrocycles, and HBr in HOAc for the sulfur containing macrocycle. The macrocycles were found to be poor catalysts for ATP hydrolysis compared to other similar polyammonium macrocycles.     

Scaffold Effects on Osteogenic Differentiation of Equine Mesenchymal Stem Cells: An In Vitro Comparative Study

The in vitro viability, osteogenic differentiation, and mineralization of four different equine mesenchymal stem cells (MSCs) from bone marrow, periosteum, muscle, and adipose tissue are compared, when they are cultured with different collagen‐based scaffolds or with fibrin glue. The results indicate that bone marrow cells are the best source of MSCs for osteogenic differentiation, and that an electrochemically aggregated collagen gives the highest cell viability and best osteogenic differentiation among the four kinds of scaffolds studied.

     

Interaction of Hydrogen with Ceria: Hydroxylation,Reduction, and Hydride Formation on the Surface and in the Bulk

The study reports the first attempt to address the interplay between surface and bulk in hydride formation in ceria (CeO₂) by combining experiment, using surface sensitive and bulk sensitive spectroscopic techniques on the two sample systems, i.e., CeO₂(111) thin films and CeO₂ powders, and theoretical calculations of CeO₂(111) surfaces with oxygen vacancies (O_v) at the surface and in the bulk. We show that, on a stoichiometric CeO₂(111) surface, H₂ dissociates and forms surface hydroxyls (OH). On the pre-reduced CeO_2−x samples, both films and powders, hydroxyls and hydrides (Ce−H) are formed on the surface as well as in the bulk, accompanied by the Ce³⁺ ↔ Ce⁴⁺ redox reaction. As the O_v concentration increases, hydroxyl is destabilized and hydride becomes more stable. Surface hydroxyl is more stable than bulk hydroxyl, whereas bulk hydride is more stable than surface hydride. The surface hydride formation is the kinetically favorable process at relatively low temperatures, and the resulting surface hydride may diffuse into the bulk region and be stabilized therein. At higher temperatures, surface hydroxyls can react to produce water and create additional oxygen vacancies, increasing its concentration, which controls the H₂/CeO₂ interaction. The results demonstrate a large diversity of reaction pathways, which have to be taken into account for better understanding of reactivity of ceria-based catalysts in a hydrogen-rich atmosphere.     

Semisynthesis of Functional Glycosylphosphatidylinositol‐Anchored Proteins

Glypiation is a common posttranslational modification of eukaryotic proteins involving the attachment of a glycosylphosphatidylinositol (GPI) glycolipid. GPIs contain a conserved phosphoglycan that is modified in a cell‐ and tissue‐specific manner. GPI complexity suggests roles in biological processes and effects on the attached protein, but the difficulties to get homogeneous material have hindered studies. We disclose a one‐pot intein‐mediated ligation (OPL) to obtain GPI‐anchored proteins. The strategy enables the glypiation of folded and denatured proteins with a natural linkage to the glycolipid. Using the strategy, glypiated eGFP, Thy1, and the Plasmodium berghei protein MSP1₁₉ were prepared. Glypiation did not alter the structure of eGFP and MSP1₁₉ proteins in solution, but it induced a strong pro‐inflammatory response in vitro. The strategy provides access to glypiated proteins to elucidate the activity of this modification and for use as vaccine candidates against parasitic infections.     

Pressure effect on heterogeneous trifluoromethylation of fullerenes and its application

The first systematic study of heterogeneous fullerene trifluoromethylation using an innovative gradient-temperature gas-solid reactor revealed a significant effect of CF₃I pressure on the conversion of C₆₀ and C₇₀ into trifluoromethylated products and on the range of fullerene(CF₃)_n compositions that were obtained. The design of the reactor allowed us to lower the residence times of fullerene(CF₃)_n species in the hot zone which resulted in the significant differences in relative isomeric distributions as compared to the earlier methods. For the first time, gram quantities of trifluoromethylated fullerenes were prepared using the new reactor, and the selective synthesis of a single-isomer C₆₀(CF₃)₂ was developed. The relative reactivity of C₇₀ as a CF₃ radical scavenger was found to be much lower than that of C₆₀, especially at an early radical addition stage, which led to the cost-efficient synthesis of C₆₀(CF₃)₂ from a fullerene extract.