A Block Inertial Bregman Proximal Algorithm for Nonsmooth Nonconvex Problems with Application to Symmetric Nonnegative Matrix Tri-Factorization

Journal of Optimization Theory and Applications - We propose BIBPA, a block inertial Bregman proximal algorithm for minimizing the sum of a block relatively smooth function (that is, relatively...     

Metal-Ion Tuning in Triple-Stranded Helicate-Based Metallosupramolecules

Effective incorporation of multiple types of ligands in a given coordination structure provides structural complexity and functional diversity to the resultant coordination-driven assembly. One of the most widely used synthetic approaches is the utilization of the molecular symmetry principle to combine multiple ligands and specific metallic centers in a preferred manner. The variation of metal ions can be helpful to understand the importance of symmetry for the generation of structurally hierarchical supramolecular platforms. We describe the synthesis and characterization of isostructural supramolecular helicates, [M₈(PDA)₆(AIP)₃(DMF)_6−x(H₂O)_x] (M=Ni ( 1 ), Co ( 2 ), and Mn ( 3 ); PDA=2,6-pyridinedicarboxylate; AIP=5-aminoisophthalate; x=0 for 1 , and x=4 for 2 and 3) . The effect of metal variation on the formation of supramolecular helicates and their solid-state crystal packing are discussed. Despite the disparity in the ionic radii and distinct coordination-geometry preferences of Co²⁺, Ni²⁺, and Mn²⁺, all metal centers engaged in the assembly with the heteroleptic ligands in the same manner to form isostructural supramolecular helicates.     

Effect of magnetic field on laminar forced convective heat transfer of MWCNT–Fe3O4/water hybrid nanofluid in a heated tube

Journal of Thermal Analysis and Calorimetry - A numerical investigation is carried out to assess the hydrothermal performance of a water-based hybrid nanofluid containing both Fe3O4 (magnetite)...     

Secondary Metabolites of the Lichen Parmotrema cristiferum

Chemistry of Natural Compounds - A new C41-spiroterpenoid, norreticulatin (1), has been isolated from the thalli of Parmotrema cristiferum together with four known compounds, anadensin (2),...     

Immobilization of an Iridium Pincer Complex in a Microporous Polymer for Application in Room-Temperature Gas Phase Catalysis

An iridium dihydride pincer complex [IrH₂(POCOP)] is immobilized in a hydroxy-functionalized microporous polymer network using the concepts of surface organometallic chemistry. The introduction of this novel, truly innocent support with remote OH-groups enables the formation of isolated active metal sites embedded in a chemically robust and highly inert environment. The catalyst maintained high porosity and without prior activation exhibited efficacy in the gas phase hydrogenation of ethene and propene at room temperature and low pressure. The catalyst can be recycled for at least four times.     

Visualizing high density clusters in multidimensional data using optimized star coordinates

Multidimensional multivariate data have been studied in different areas for quite some time. Commonly, the analysis goal is not to look into individual records but to understand the distribution of the records at large and to find clusters of records that exhibit correlations between dimensions or variables. We propose a visualization method that operates on density rather than individual records. To not restrict our search for clusters, we compute density in the given multidimensional space. Clusters are formed by areas of high density. We present an approach that automatically computes a hierarchical tree of high density clusters. For visualization purposes, we propose a method to project the multidimensional clusters to a 2D or 3D layout. The projection method uses an optimized star coordinates layout. The optimization procedure minimizes the overlap of projected clusters and maximally maintains the cluster shapes, compactness, and distribution. The star coordinate visualization allows for an interactive analysis of the distribution of clusters and comprehension of the relations between clusters and the original dimensions. Clusters are being visualized using nested sequences of density level sets leading to a quantitative understanding of information content, patterns, and relationships.     

Quantitative evaluation method for electroluminescence images of a‐Si:H thin‐film solar modules

This work presents a method for extracting the absolute local junction voltage of a‐Si:H thin‐film solar cells and modules from electroluminescence (EL) images. It is shown that the electroluminescent emission of a‐Si:H devices follows a diode law with a radiative ideality factor n_r larger than one. We introduce an evaluation method that allows us to determine the absolute local junction voltage in cases of n_r > 1, while existing approaches rely on the assumption of n_r = 1. Furthermore, we find that the experimentally determined values of n_r vary from sample to sample. It is also explained why the derived radiative ideality factor is influenced by the spectral sensitivity of the camera system used in the experiment. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Functional initiators for the ring-opening polymerization of polyesters and polycarbonates: An overview

Functional ring-opening polymerization (ROP) initiators can instill a wide array of chemical, physical, and biological effects into a polymeric chain. Highlighting the versatility of this “active” initiator approach, a broad range of characteristics can be achieved through the use of initiators with chemistries spanning from drugs and dyes (key in the case of drug delivery or nanoparticle applications) through to radically active monomers, polymerization transfer agents, and catalysts. The selection of a suitable “active” initiator (monomers for tandem reactions, dyes, drugs, stereo-catalysts, etc.) can not only provide the final polymers with interesting application potential but also facilitate the implementation of ROP reactions in tandem with other polymerization techniques. Overall, this review will highlight that functionalities and properties can be effectively tuned by exploiting simple chemistry approaches, allowing readers to identify how these approaches could be of benefit to their own work in a range of applications including drug/gene delivery, amphiphilic bio/degradable carriers, drug/scent controlled release, and stereo-controlled polymers.     

Total Synthesis and Antimycobacterial Activity of Ohmyungsamycin A,Deoxyecumicin, and Ecumicin

The ohmyungsamycin and ecumicin natural product families are structurally related cyclic depsipeptides that display potent antimycobacterial activity. Herein the total syntheses of ohmyungsamycin A, deoxyecumicin, and ecumicin are reported, together with the direct biological comparison of members of these natural product families against Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis (TB). The synthesis of each of the natural products employed a solid-phase strategy to assemble the linear peptide precursor, involving a key on-resin esterification and an optional on-resin dimethylation step, before a final solution-phase macrolactamization between the non-proteinogenic N-methyl-4-methoxy-l -tryptophan amino acid and a bulky N-methyl-l -valine residue. The synthetic natural products possessed potent antimycobacterial activity against Mtb with MIC₉₀’s ranging from 110–360 nm and retained activity against Mtb in Mtb-infected macrophages. Deoxyecumicin also exhibited rapid bactericidal killing against Mtb, sterilizing cultures after 21 days.