2-Amino-3-cyano-4H-chromene-4-ylphosphonates as potential antiviral agents: Synthesis,in ovo and in silico approach

A simplistic synthetic procedure for the synthesis of structurally diversified 2-amino-3-cyano-4H-chromene-4-ylphosphonates ( 4a-j ) were developed by the treatment of substituted salicylaldehydes, malononitrile, and dialkyl phosphite in presence of Cu(OAc)₂ catalyst at room temperature and neat conditions. The synthesized compounds were tested for their antiviral assay. Among all, the compounds 4a , 4d and 4h have shown good in ovo antiviral activity against New castle disease virus (NDV) at a concentration of 150 μg/mL. The remarkable reduction in NDV virus population in embryos treated with title compounds ( 4a-j ) in a dose dependent manner, indicated that the synthesized compounds are extreme by toxic to the NDV virus. The title compounds were also docked against hemagglutinin neuraminidase enzyme and the more bioactive compound 4a showed highest docking score than the standard antiviral drug taribavirin while the compounds 4d and 4h has the same docking score as that of the standard.     

Synthesis and functionalization of dendron‐polymer conjugate based hydrogels via sequential thiol‐ene “click” reactions

Fabrication and functionalization of hydrogels from well‐defined dendron‐polymer‐dendron conjugates is accomplished using sequential radical thiol‐ene “click” reactions. The dendron‐polymer conjugates were synthesized using an azide‐alkyne “click” reaction of alkene‐containing polyester dendrons bearing an alkyne group at their focal point with linear poly(ethylene glycol)‐bisazides. Thiol‐ene “click” reaction was used for crosslinking these alkene functionalized dendron‐polymer conjugates using a tetrathiol‐based crosslinker to provide clear and transparent hydrogels. Hydrogels with residual alkene groups at crosslinking sites were obtained by tuning the alkene‐thiol stoichiometry. The residual alkene groups allow efficient postfunctionalization of these hydrogel matrices with thiol‐containing molecules via a subsequent radical thiol‐ene reaction. The photochemical nature of radical thiol‐ene reaction was exploited to fabricate micropatterned hydrogels. Tunability of functionalization of these hydrogels, by varying dendron generation and polymer chain length was demonstrated by conjugation of a thiol‐containing fluorescent dye. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 926–934     

Validation of the S‐CLSVOF method with the density‐scaled balanced continuum surface force model in multiphase systems coupled with thermocapillary flows

Three numerical methods, namely, volume of fluid (VOF), simple coupled volume of fluid with level set (S‐CLSVOF), and S‐CLSVOF with the density‐scaled balanced continuum surface force (CSF) model, have been incorporated into OpenFOAM source code and were validated for their accuracy for three cases: (i) an isothermal static case, (ii) isothermal dynamic cases, and (iii) non‐isothermal dynamic cases with thermocapillary flow including dynamic interface deformation. Results have shown that the S‐CLSVOF method gives accurate results in the test cases with mild computation conditions, and the S‐CLSVOF technique with the density‐scaled balanced CSF model leads to accurate results in the cases of large interface deformations and large density and viscosity ratios. These show that these high accuracy methods would be appropriate to obtain accurate predictions in multiphase flow systems with thermocapillary flows. Copyright © 2016 John Wiley & Sons, Ltd.     

Invariant subspaces generated by a single function in the Polydisk

Mathematical Notes - It is proved that any Busemann nonpositively curved G-space of cone type is isometric to a finite-dimensional normed space with strictly convex norm.     

Chemical and structural characterization of α-N-acetylgalactosaminidase I and II from starfish, <Emphasis Type="Italic">asterina amurensis</Emphasis>

Background

The marine invertebrate starfish was found to contain a novel α-N-acetylgalactosaminidase, α-GalNAcase II, which catalyzes removal of terminal α-N-acetylgalactosamine (α-GalNAc), in addition to a typical α-N-acetylgalactosaminidase, α-GalNAcase I, which catalyzes removal of terminal α-N-acetylgalactosamine (α-GalNAc) and, to a lesser extent, galactose. The interrelationship between α-GalNAcase I and α-GalNAcase II and the molecular basis of their differences in substrate specificity remain unknown.

Results

Chemical and structural comparisons between α-GalNAcase I and II using immunostaining, N-terminal amino acid sequencing and peptide analysis showed high homology to each other and also to other glycoside hydrolase family (GHF) 27 members. The amino acid sequence of peptides showed conserved residues at the active site as seen in typical α-GalNAcase. Some substitutions of conserved amino acid residues were found in α-GalNAcase II that were located near catalytic site. Among them G171 and A173, in place of C171 and W173, respectively in α-GalNAcase were identified to be responsible for lacking intrinsic α-galactosidase activity of α-GalNAcase II. Chemical modifications supported the presence of serine, aspartate and tryptophan as active site residues. Two tryptophan residues (W16 and W173) were involved in α-galactosidase activity, and one (W16) of them was involved in α-GalNAcase activity.

Conclusions

The results suggested that α-GalNAcase I and II are closely related with respect to primary and higher order structure and that their structural differences are responsible for difference in substrate specificities.

     

Cordierite-based refractory ceramics from natural halloysite and peridotite: Insights on technological properties

Cordierite-based ceramics were fabricated from Moroccan natural halloysite clay by using a simple and low-cost manufacturing method. To this end, peridotite and halloysite samples, collected from Beni Bousera and Melilla sites, Morocco, were used as raw materials for ceramics manufacturing. A starting mixture was prepared (76.08 wt% of clay and 23.92 wt% of peridotite), molded and heated to the desired temperature (1250, 1300 and 1350 °C) to fabricate cordierite ceramic specimens. Both raw materials (peridotite and halloysite) and final ceramics were analyzed using routine characterization techniques including chemical analysis by XRF, mineralogical analysis by XRD, thermogravimetric analysis, and morphological characteristics using scanning electron microscopy (SEM). The prepared ceramics were investigated regarding their mineralogical composition, thermal and technological properties, chemical resistance, and microstructural characteristics. Our results indicated that peridotite sample is mainly composed of silica (40.25 wt%) and magnesia (38.05 wt%) while halloysite is consisted essentially of silica (38.00 wt%) and alumina (34.13 wt%). This was confirmed by XRD, TG-DTA and FTIR analyses. The prepared ceramic specimens at different sintering temperatures (i.e., 1250, 1300 and 1350 °C) have regular cylindrical forms, displaying good ceramic properties. This is consolidated with the main technological tests including porosity (4.56–3.11%), bulk density (2.45–2.78 g/cm³), shrinkage (6.51–10.31%), indirect tensile strength (20.35–27.60 MPa), and low linear thermal expansion coefficient (3.05–2.18 × 10^?6/°C). Cordierite specimen prepared at 1350 °C provided the best ceramic sample with the highest technological properties, good chemical resistance and thermal properties. Thus, naturally abundant halloysite and peridotite deposits are potential candidates for cordierite-based ceramic manufacture. Therefore, the achieved results have provided cost-effective ceramic bricks with physical, thermal and mechanical properties that are favorable to be used as refractory bricks.     

On the mechanism of spray formation from liquid jets

A fundamental physical mechanism whereby sprays are formed from liquid jets is formulated. It is shown that a combination of axial disturbances cannot produce the necessary conditions for non-axial evolution of drops. These conditions are satisfied by a non-axial sequence of superimposed disturbances, propagating one on top of the other. The resulting model is used to describe the evolution of liquid jets into sprays. It is postulated that every consecutive superimposed disturbance, which is characterized by a self-instability parameter, travels tangent to the surface that supports its propagation. Model outputs show that starting from the first superimposed disturbance, highly complex profiles of the jet surface are generated. Fourier analysis of the derived superimposed disturbance functions is performed in conjunction with the basic building blocks of classic instability theory. This is achieved by assigning to each term a self-instability factor. The sum of these building blocks results in intricate profiles of the jet. In these profiles, multiplicity of radial position of the jet interface as a function of axial distance provides the necessary conditions for evolution of non-axial drops. The model accuracy, which depends on the disturbance rank, is sufficient to disclose the mechanism that turns the jet into a spray. The observed jump in the level of error is commensurate with the sudden increase in flow complexity that follows an increase in the disturbance rank. Finally, model outputs are used to study the effect of instability parameters on the evolution patterns of the jet and the non-axial discharge of drops.     

Synthesis of dibenzo‐16‐crown‐5 compounds with pendant ester and ether groups

Structurally related dibenzo‐16‐crown‐5 lariat ethers with pendant ester and ether groups are prepared. Structural variations within the series of alkyl lariat ether esters include changes in the O‐alkyl group, attachment site and nature of the lipophilic group, and length of the spacer, which connects the ester group to the polyether framework. Also synthesized are bis(crown ether) diesters with two dibenzo‐16‐crown‐5 or two dicyclohexano‐16‐crown‐5 units and two ester groups connected to each other by a linker of varying length. Synthetic strategies for the preparation of these lariat ethers with pendant ester‐ and ether‐containing side arms are described.     

Synthesis of proton‐ionizable acyclic,macrocyclic and macrobicyclic compounds containing one or two triazole groups

New acyclic, macrocyclic and macrobicyclic compounds containing one or two proton‐ionizable triazole groups are prepared and characterized. The series includes six podands, a macrocycle with one triazole and one pyridine unit in the ring, a bis‐triazolo macrocycle with four pentafluorobenzyl substitutents, and two bis(crown ethers) with a triazolo group connecting the two polyether rings. The solid‐state structure and solubility in supercritical carbon dioxide are determined for the bis‐triazolo macrocycle with pendant pentafluorobenzyl groups.     

Application of P-stereogenic aminophosphine phosphinite ligands in asymmetric hydroformylation

New chiral aminophosphine phosphinite ligands with a stereogenic center at the aminophosphine phosphorus atom were prepared based on (R,S)-ephedrine as the chiral auxiliary and backbone. Substituents at the chiral aminophosphine as well as at the phosphinite phosphorus atom were varied. These new ligands were applied to the rhodium-catalyzed asymmetric hydroformylation of vinyl arenes. The enantiomeric excess reached up to 77%. 1H and 31P NMR studies of the Rh complexes under syngas pressure reveal that [HRh(CO)2(PP)] complexes with the NP* moiety in an axial position are responsible for enantioselectivity.