Displacement of droplets on a vibrating structure

A water droplet placed on a vibrating surface moves toward the antinode of the vibration. The acoustic radiation pressure can explain this non-linear phenomenon. In this paper, the use of a piezoelectric actuator to produce a displacement of liquid droplets is pointed out. Due to geometry of the actuator and the position of piezoelectric ceramics, it is possible to generate stationary modes in the structure where the nodal lines can move.     

Hydroxymethylated Dioxobilins in Senescent Arabidopsis thaliana Leaves: Sign of a Puzzling Biosynthetic Intermezzo of Chlorophyll Breakdown

1‐Formyl‐19‐oxobilin‐type tetrapyrroles are characteristic, abundant products of chlorophyll breakdown in senescent leaves. However, in some leaves, 1,19‐dioxobilin‐type chlorophyll catabolites (DCCs) lacking the formyl group accumulate instead. A P450 enzyme was identified in in vitro studies that removed the formyl group of a primary fluorescent chlorophyll catabolite (pFCC) and generated fluorescent DCCs. These DCCs are precursors of isomeric nonfluorescent DCCs (NDCCs). Here, we report a structural investigation of the NDCCs in senescent leaves of wild‐type Arabidopsis thaliana. Four new NDCCs were characterized, two of which carried a stereoselectively added hydroxymethyl group. Such formal DCC hydroxymethylations were previously found in DCCs in leaves of a mutant of A. thaliana. They are now indicated to be a feature of chlorophyll breakdown in A. thaliana, associated with the specific in vivo deformylation of pFCC en route to NDCCs.     

Bi(OTf)3-catalyzed cycloisomerization of aryl-allenes

Intramolecular hydroarylation of allenes was achieved under very mild conditions using bismuth(III) triflate as the catalyst. Efficient functionalization of activated and nonactivated aromatic nuclei led to C-C bond formation through a formal Ar-H activation. A tandem bis-hydroarylation of the allene moiety was also developed giving access to various interesting polycyclic structures.     

N-donor ligands based on bipyridine and ionic liquids: an efficient partnership to stabilize rhodium colloids. Focus on oxygen-containing compounds hydrogenation

Polynitrogen ligands and/in ionic liquids (ILs) are described as a pertinent tandem to efficiently stabilize rhodium nanoparticles (NPs) in the size range of 2.0 nm for catalytic applications. Several N-donor ligands based on bipyridine skeleton were used as extra protective agents in [BMI][PF(6)] and compared in the hydrogenation of functionalized aromatic compounds at 80 °C and under 40 bar H(2). The nature of the bipyridine derivative and its influence on the coordination mode on the particle surface were proposed to explain the observed different kinetic properties. The hydrogenation of various oxygen-containing arenes was investigated and original results were described in the reduction of anisole and cresols as model lignin compounds, providing a significant ratio of ketone derivatives. A first explanation based on possible reaction routes is proposed to justify the formed products.     

Targeted energy transfer with parallel nonlinear energy sinks. Part I: Design theory and numerical results

In this paper, we study a Targeted Energy Transfer (TET) problem between a p degrees-of-freedom (dof) linear master structure and several coupled parallel slave Nonlinear Energy Sink (NES) systems. In detail, each lth dof l=1,2,…,p contains n _l parallel NES; so the linear structure has (n ₁+n ₂+⋅⋅⋅+n _l +⋅⋅⋅+n _p ) NES. We are interested to study analytically the TET phenomenon during the first mode of the compound system. To this end, complexification, averaging, and multiple scales methods are used.     

STM observations of the first polymerization steps between hexahydroxy-tri-phenylene and benzene-di-boronic acid molecules

To understand the first polymerization steps between benzene-diboronic acid (BDBA) and hexahydroxy-triphenylene (HHTP) molecules, the peculiar self assemblies of HHTP molecules on an Ag(111) surface have been investigated in terms of substrate temperature during evaporation. Interaction of these different molecular structures with BDBA moieties has been researched. The results show that polymer tecton is based on an oligomer composed of one BDBA surrounded by two HHTPs, its shape being independent of the surrounding HHTP network. The geometry and functionality of this tecton determines the shape of the final structures obtained after covalent bonding.     

On the Design of Zinc‐Finger Models with Cyclic Peptides Bearing a Linear Tail

Cyclic peptides with a linear tail (CPLT) have been successfully used to model two zinc fingers (ZFs) adopting the treble‐clef‐ and loosened zinc‐ribbon folds. In this article, we examine the factors that may influence the design of such ZF models: mutations in the sequence, size of the cycle, and size of the tail. For this purpose, several peptides derived from the CPLT‐based models of the treble‐clef‐ and loosened zinc‐ribbon ZF were synthesized and studied. CPLT‐based models appear to be robust toward mutations, accommodate various cycle sizes, and are sensible to the size of the linking region of the tail located between the cycle and the coordinating amino acids. Based on these criteria, we describe the design of a new CPLT‐based model for the zinc‐ribbon ZFs, L_ZR, and compare it to a linear analogue, L_ZR^lin. The model complex Zn ? L_ZR is able to fold correctly around the metal ion contrary to Zn ? L_ZR^lin, suggesting that CPLT‐based models are more likely to yield structurally meaningful models of ZF sites than linear peptide models. Finally, we draw some rules that could allow the design of new CPLT‐based metallopeptides with a controlled fold.     

Numerical solution of Cauchy problems in linear elasticity in axisymmetric situations

An iterative method for solving axisymmetric Cauchy problems in linear elasticity is presented. This kind of problem consists in recovering missing displacements and forces data on one part of a domain boundary from the knowledge of overspecified displacements and forces data on another part of this boundary. Numerical simulations using the finite element method highlight the algorithm’s efficiency, accuracy and robustness to noisy data as well as its ability to deblur noisy data. An application of the inverse technique to the identification of a friction coefficient is also presented.     

Individual particle handling in a microfluidic system based on parallel laser trapping

We present an optical trapping system combining individually addressable multiple laser traps with fluorescence spectroscopy. An in-line set of 64 near-IR laser diodes is used to create a line of individually addressable traps inside a microfluidic chip. This system is completed by an excitation/detection line for spectrally resolved fluorescence imaging of trapped particles. Highly parallel trapping in a constant flow (up to a few millimeters per second), fast particle handling rates (up to a few particles per second), and the possibility of recording fluorescence spectra of trapped objects lead to a performing bioanalytical platform, e.g., for highly parallel analysis and sorting.