Encapsulation of Crabtree's Catalyst in Sulfonated MIL‐101(Cr): Enhancement of Stability and Selectivity between Competing Reaction Pathways by the MOF Chemical Microenvironment

Crabtree's catalyst was encapsulated inside the pores of the sulfonated MIL‐101(Cr) metal–organic framework (MOF) by cation exchange. This hybrid catalyst is active for the heterogeneous hydrogenation of non‐functionalized alkenes either in solution or in the gas phase. Moreover, encapsulation inside a well‐defined hydrophilic microenvironment enhances catalyst stability and selectivity to hydrogenation over isomerization for substrates bearing ligating functionalities. Accordingly, the encapsulated catalyst significantly outperforms its homogeneous counterpart in the hydrogenation of olefinic alcohols in terms of overall conversion and selectivity, with the chemical microenvironment of the MOF host favouring one out of two competing reaction pathways.     

Crystal structure of the meta hydroxyl phenyl analog of α(+)-prodine

The meta hydroxyphenyl analog of -prodine (1,3-dimethyl-(4-meta-hydroxy phenyl)-4-propionyloxypiperidine) free base crystallizes in the orthorhombic space group P2₁2₁2₁. The relative configuration of the compound shows the piperidine ring is in a chair conformation, the phenyl ring, the 3-methyl, and the N-methyl are equatorial, and the 4-propionyloxy group is axial. The molecular structure is similar to that of racemic -prodine and the potent opioid agonist, ketobemidone. There is a hydrogen bond between N(1) ... O(1) 2.79 Å.     

An architecture independent study of parallel segment trees

We study the computation, communication and synchronization requirements related to the construction and search of parallel segment trees in an architecture independent way. Our proposed parallel algorithms are optimal in space and time compared to the corresponding sequential algorithms utilized to solve the introduced problems and are described in the context of the bulk-synchronous parallel (BSP) model of computation. Our methods are more scalable and can thus be made to work for larger values of processor size p relative to problem size n than other segment tree related algorithms that have been described on other realistic distributed-memory parallel models and also provide a natural way to approach searching problems on latency-tolerant models of computation that maintains a balanced query load among the processors.     

Investigation of the cytotoxicity of bioinspired coumarin analogues towards human breast cancer cells

Molecular Diversity - Coumarins possess a wide array of therapeutic capabilities, but often with unclear mechanism of action. We tested a small library of 18 coumarin derivatives against human...     

Gaining Insights on the Interactions of a Class of Decorated (2-([2,2′-Bipyridin]-6-yl)phenyl)platinum Compounds with c-Myc Oncogene Promoter G-Quadruplex and Other DNA Structures

Organometallic molecules offer some of the most promising scaffolds for interaction with G-quadruplex nucleic acids. We report the efficient synthesis of a family of organoplatinum(II) complexes, featuring a 2-([2,2′-bipyridin]-6-yl)phenyl tridentate (N^∧N^∧C) ligand, that incorporates peripheral side-chains aiming at enhancing and diversifying its interaction capabilities. These include a di-isopropyl carbamoyl amide, a morpholine ethylenamide, two enantiomeric proline imides and an oxazole. The binding affinities of the Pt-complexes were evaluated via UV-vis and fluorescence titrations, against 5 topologically-distinct DNA structures, including c-myc G-quadruplex, two telomeric (22AG) G-quadruplexes, a duplex (ds26) and a single-stranded (polyT) DNA. All compounds exhibited binding selectivity in favour of c-myc, with association constants (K_a) in the range of 2–5×10⁵ M⁻¹, lower affinity for both folds of 22AG and for ds26 and negligible affinity for polyT. Remarkable emission enhancements (up to 200-fold) upon addition of excess DNA were demonstrated by a subset of the compounds with c-myc, providing a basis for optical selectivity, since optical response to all other tested DNAs was low. A c-myc DNA-melting experiment showed significant stabilizing abilities for all compounds, with the most potent binder, the morpholine-Pt-complex, exhibiting a ΔT_m>30 °C, at 1 : 5 DNA-to-ligand molar ratio. The same study implied contributions of the diverse side-chains to helix stabilization. To gain direct evidence of the nature of the interactions, mixtures of c-myc with the four most promising compounds were studied via UV Resonance Raman (UVRR) spectroscopy, which revealed end-stacking binding mode, combined with interactions of side-chains with loop nucleobase residues. Docking simulations were conducted to provide insights into the binding modes for the same four Pt-compounds, suggesting that the binding preference for two alternative orientations of the c-myc G-quadruplex thymine ‘cap’ (‘open’ vs. ‘closed’), as well as the relative contributions to affinity from end-stacking and H-bonding, are highly dependent on the nature of the interacting Pt-complex side-chain.     

Parallelized phylogenetic post-analysis on multi-core architectures

Bioinformatics is experiencing a rapid and overwhelming accumulation of molecular sequence data, predominantly driven by novel wet-lab sequencing techniques. This trend poses scalability challenges for tool developers. In the field of phylogenetic inference (reconstruction of evolutionary trees from molecular sequence data), scalability is becoming an increasingly important issue for operations other than the tree reconstruction itself. In this paper we focus on post-analysis tasks in reconstructing very large trees, specifically the step of building (extended) majority rule consensus trees from a collection of equally plausible trees or a collection of bootstrap replicate trees. To this end we present non-parallel optimizations which establish our implementation as the fastest exact implementation in phylogenetics, and our novel parallelized routines are the first of their kind. Our non-parallel optimizations achieve a performance improvement of factor 50 compared to the previous version of our code and we achieve a maximum speedup of 5.5 on a 8-core Nehalem node for building consensus trees comprising up to 55,000 organisms. We also present a parallel approach for drawing bootstrap support values on a candidate tree, and experimentally assess our approach in order to better understand read-only versus read–write parallel hash table accesses on multi-core systems.     

On the Beavers–Joseph Interface Condition for Non-parallel Coupled Channel Flow over a Porous Structure at High Reynolds Numbers

Transport in Porous Media - Stereolithographic 3D printing is of paramount interest for researchers studying porous media because it is possible to use resins with a wide range of physical and...