High Efficient and Stable Thiol-Modified Dendritic Mesoporous Silica Nanospheres Supported Gold catalysts for Gas-phase Selective Oxidation of Benzyl Alcohol with Ultra-Long Lifetime

Thiol-modified dendritic mesoporous silica nanospheres (DMSNs) supported Au catalyst were facilely prepared and used in gas-phase selective oxidation of benzyl alcohol with O2 as the oxidant. The Au/DMSNs-4.4%SH catalyst with low loading of Au (~2%) and proper amount of thiol ligand (~4.4%) achieved high conversion of benzyl alcohol (Conv. 91%) and selectivity for benzaldehyde (Sel. 98%) and unprecedented lifetime up to 820 h at 250 °C. The dramatically increased lifetime is the consequence of the strong stabilization of active gold nanoparticles by thiol ligand and the effective mass diffusion of DMSNs with opened three-dimensional mesoporous networks.

Magnetically Recoverable Nanoparticulate Catalysts for Cross-Coupling Reactions: The Dendritic Support Influences the Catalytic Performance

Carbon-carbon cross-coupling reactions are among the most important synthetic tools for the preparation of pharmaceuticals and bioactive compounds. However, these reactions are normally carried out using copper, phosphines, and/or amines, which are poisonous for pharmaceuticals. The use of nanocomposite catalysts holds promise for facilitating these reactions and making them more environmentally friendly. In the present work, the PEGylated (PEG stands for poly(ethylene glycol) pyridylphenylene dendrons immobilized on silica loaded with magnetic nanoparticles have been successfully employed for the stabilization of Pd2+ complexes and Pd nanoparticles. The catalyst developed showed excellent catalytic activity in copper-free Sonogashira and Heck cross-coupling reactions. The reactions proceeded smoothly in green solvents at low palladium loading, resulting in high yields of cross-coupling products (from 80% to 97%) within short reaction times. The presence of magnetic nanoparticles allows easy magnetic separation for repeated use without a noticeable decrease of catalytic activity due to the strong stabilization of Pd species by rigid and bulky dendritic ligands. The PEG dendron periphery makes the catalyst hydrophilic and better suited for green solvents. The minor drop in activity upon the catalyst reuse is explained by the formation of Pd nanoparticles from the Pd2+ species during the catalytic reaction. The magnetic separation and reuse of the nanocomposite catalyst reduces the cost of target products as well as energy and material consumption and diminishes residual contamination by the catalyst. These factors as well as the absence of copper in the catalyst makeup pave the way for future applications of such catalysts in cross-coupling reactions.

Use of the Extensor Carpi Ulnaris Half-Slip for Treating Chronic Neglected Volar Dislocation of the Distal Radioulnar Joint

Volar dislocation of the distal radioulnar joint (DRUJ) is a rare injury. Furthermore, few reports exist regarding DRUJ dislocation with simultaneous elbow dislocation. Elbow dislocation is easily diagnosed and reduced, whereas a DRUJ dislocation is easily missed because of an inaccurate or missed examination of the wrist, which results in a chronic condition. We experienced a case of simultaneous elbow and volar DRUJ dislocation; the latter was found 2 months postinjury. To treat chronic volar dislocation of the DRUJ, surgical methods should include reconstruction of the triangle fibrocartilage complex because of scar tissue and severe instability. In this paper, we describe triangle fibrocartilage complex reconstruction by using the extensor carpi ulnaris half-slip. It is the first report of applying this technique for chronic volar DRUJ dislocation. This technique has a role in creating strong stabilization of the DRUJ and can be an effective treatment option.

Imide Condensation as a Strategy for the Synthesis of Core Diversified G-Quadruplex Ligands with Anti-Cancer and Anti-Parasitic Activity

<p>A facile imide coupling strategy for the one-step preparation of G‑quadruplex ligands with varied core chemistries is described. The G‑quadruplex stabilization, anticancer and antiparasitic activity of a library of nine compounds was examined, identifying a nanomolar inhibitor of <i>T. brucei</i> with 78‑fold selectivity over MRC5 cells, and strong stabilization of G‑quadruplex nucleic acids. </p>

Imide Condensation as a Strategy for the Synthesis of Core Diversified G-Quadruplex Ligands with Anti-Cancer and Anti-Parasitic Activity

<p>A facile imide coupling strategy for the one-step preparation of G‑quadruplex ligands with varied core chemistries is described. The G‑quadruplex stabilization, anticancer and antiparasitic activity of a library of nine compounds was examined, identifying a nanomolar inhibitor of <i>T. brucei</i> with 78‑fold selectivity over MRC5 cells, and strong stabilization of G‑quadruplex nucleic acids. </p>

Weak and strong stabilization for time-delay semi-linear systems governed by constrained feedback control

This paper is concerned with the issue of weak and strong stabilization for distributed semi-linear systems with time delay using a constrained feedback control. The results of the semi-linear systems without delay are generalized for strong and weak stabilization cases. Illustrating applications to hyperbolic and parabolic equations are considered.

Terminal Mono- and Bis-Conjugates of Oligonucleotides with Closo-Dodecaborate: Synthesis and Physico-Chemical Properties

Oligonucleotide conjugates with boron clusters have found applications in different fields of molecular biology, biotechnology, and biomedicine as potential agents for boron neutron capture therapy, siRNA components, and antisense agents. Particularly, the closo-dodecaborate anion represents a high-boron-containing residue with remarkable chemical stability and low toxicity, and is suitable for the engineering of different constructs for biomedicine and molecular biology. In the present work, we synthesized novel oligonucleotide conjugates of closo-dodecaborate attached to the 5′-, 3′-, or both terminal positions of DNA, RNA, 2′-O-Me RNA, and 2′-F-Py RNA oligomers. For their synthesis, we employed click reaction with the azido derivative of closo-dodecaborate. The key physicochemical characteristics of the conjugates have been investigated using high-performance liquid chromatography, gel electrophoresis, UV thermal melting, and circular dichroism spectroscopy. Incorporation of closo-dodecaborate residues at the 3′-end of all oligomers stabilized their complementary complexes, whereas analogous 5′-modification decreased duplex stability. Two boron clusters attached to the opposite ends of the oligomer only slightly influence the stability of complementary complexes of RNA oligonucleotide and its 2′-O-methyl and 2′-fluoro analogs. On the contrary, the same modification of DNA oligonucleotides significantly destabilized the DNA/DNA duplex but gave a strong stabilization of the duplex with an RNA target. According to circular dichroism spectroscopy results, two terminal closo-dodecaborate residues cause a prominent structural rearrangement of complementary complexes with a substantial shift from the B-form to the A-form of the double helix. The revealed changes of key characteristics of oligonucleotides caused by incorporation of terminal boron clusters, such as the increase of hydrophobicity, change of duplex stability, and prominent structural changes for DNA conjugates, should be taken into account for the development of antisense oligonucleotides, siRNAs, or aptamers bearing boron clusters. These features may also be used for engineering of developing NA constructs with pre-defined properties.