Room‐Temperature Decarboxylative Alkynylation of Carboxylic Acids Using Photoredox Catalysis and EBX Reagents

Alkynes are used as building blocks in synthetic and medicinal chemistry, chemical biology, and materials science. Therefore, efficient methods for their synthesis are the subject of intensive research. Herein, we report the direct synthesis of alkynes from readily available carboxylic acids at room temperature under visible‐light irradiation. The combination of an iridium photocatalyst with ethynylbenziodoxolone (EBX) reagents allowed the decarboxylative alkynylation of carboxylic acids in good yields under mild conditions. The method could be applied to silyl‐, aryl‐, and alkyl‐ substituted alkynes. It was particularly successful in the case of α‐amino and α‐oxo acids derived from biomass.     

On a single discrete scale for preventive maintenance with two shock processes affecting a complex system

A new approach to optimal maintenance of systems (networks) is suggested. It is applied to systems subject to two external independent shock processes. A system ‘consists’ of two parts, and each shock process affects only its own part. A new notion of bivariate signature is suggested and used for obtaining survival characteristics of a system and further optimization of the preventive maintenance actions. The preventive maintenance optimization is considered in the univariate discrete scale that counts the overall numbers of shocks of both types. An example of a transportation network is considered. Copyright © 2016 John Wiley & Sons, Ltd.     

The Cancer Genetics Network: recruitment results and pilot studies

OBJECTIVE: The National Cancer Institute established the Cancer Genetics Network (CGN) to support collaborative investigations into the genetic basis of cancer susceptibility, explore mechanisms to integrate this new knowledge into medical practice, and identify ways of addressing the associated psychosocial, ethical, legal, and public health issues. SUBJECTS AND METHODS: The CGN has developed the complex infrastructure required to support the projects, including the establishment of guidelines and policies, uniform methods, standard questionnaires to be used by all of the centers, and a standard format for submission of data to the Informatics Center. Cancer patients and their family members have been invited to enroll and be included in a pool of potential study participants. The Information Technology Group is responsible for support of the design, implementation, and maintenance of the multicenter Network-wide research protocols. RESULTS: As of January 2004, the CGN contained data on 23,995 probands (participants) and 425,798 family members. As a resource for cancer genetic studies, the CGN has a large number of probands and first-degree relatives with and without cancer and with multiple ethnicities. Different study designs can be used including case-control, case-case, and family studies. CONCLUSIONS: The unique resources of the CGN are available for studies on cancer genetic susceptibility, translational research, and behavioral research. The CGN is now at a point where approved collaborators may have access to enrolled patients and their families for special studies, as well as to the clinical, environmental and family cancer history data banked in the Informatics Center.     

Copolymer nanosphere encapsulated CdS quantum dots prepared by RAFT copolymerization: synthesis,characterization and mechanism of formation

Cadmium sulfide (CdS) quantum dots (QDs) encapsulated in block copolymer spheres were synthesized by an aqueous emulsion polymerization process. First, stable dispersions of CdS QDs in water were prepared using a polymer dispersant, either poly(acrylic acid) or a random copolymer having an average of ten acrylic acid and five butyl acrylate units. These polymer dispersants were prepared by reversible addition-fragmentation chain transfer polymerization. Then, the CdS QDs dispersed in water were encapsulated in a polystyrene shell using an emulsion polymerization process. Spectroscopic and microscopic techniques were used to characterize the resulting nanocomposites. Optical properties of QDs in polymer microspheres were investigated by UV-vis and fluorescence spectroscopic studies. Particle sizes of all CdS QD samples were calculated from absorption edges using Henglein's empirical curve. Transmission electron microscopy was used to determine the size and morphology of CdS QD samples. These observations were used to elucidate the mechanism of formation of the resulting well-defined polymer-encapsulated CdS nanoparticles.     

Electrospinning of a functional perfluorinated block copolymer as a powerful route for imparting superhydrophobicity and corrosion resistance to aluminum substrates

Superhydrophobic aluminum surfaces with excellent corrosion resistance were successfully prepared by electrospinning of a novel fluorinated diblock copolymer solution. Micro- and nanostructuration of the diblock copolymer coating was obtained by electrospinning which proved to be an easy and cheap electrospinning technology to fabricate superhydrophobic coating. The diblock copolymer is made of poly(heptadecafluorodecylacrylate-co-acrylic acid) (PFDA-co-AA) random copolymer as the first block and polyacrylonitrile (PAN) as the second one. The fluorinated block promotes hydrophobicity to the surface by reducing the surface tension, while its carboxylic acid functions anchor the polymer film onto the aluminum surface after annealing at 130 °C. The PAN block of this copolymer insures the stability of the structuration of the surface during annealing, thanks to the infusible character of PAN. It is also demonstrated that the so-formed superhydrophobic coating shows good adhesion to aluminum surfaces, resulting in excellent corrosion resistance.     

The molecular basis of pharmacological chaperoning in human α-galactosidase

Fabry disease patients show a deficiency in the activity of the lysosomal enzyme α-galactosidase (α-GAL or α-Gal A). One proposed treatment for Fabry disease is pharmacological chaperone therapy, where a small molecule stabilizes the α-GAL protein, leading to increased enzymatic activity. Using enzyme kinetics, tryptophan fluorescence, circular dichroism, and proteolysis assays, we show that the pharmacological chaperones 1-deoxygalactonojirimycin (DGJ) and galactose stabilize the human α-GAL glycoprotein. Crystal structures of complexes of α-GAL and chaperones explain the molecular basis for the higher potency of DGJ over galactose. Using site-directed mutagenesis, we show the higher potency of DGJ results from an ionic interaction with D170. We propose that protonation of D170 in acidic conditions leads to weaker binding of DGJ. The results establish a biochemical basis for pharmacological chaperone therapy applicable to other protein misfolding diseases.     

Solid phase extraction of DNA from biological samples in a post-based, high surface area poly(methyl methacrylate) (PMMA) microdevice

This work describes the performance of poly(methyl methacrylate) (PMMA) microfluidic DNA purification devices with embedded microfabricated posts, functionalized with chitosan. PMMA is attractive as a substrate for creating high surface area (SA) posts for DNA capture because X-ray lithography can be exploited for extremely reproducible fabrication of high SA structures. However, this advantage is offset by the delicate nature of the posts when attempting bonding to create a closed system, and by the challenge of functionalizing the PMMA surface with a group that invokes DNA binding. Methods are described for covalent functionalization of the post surfaces with chitosan that binds DNA in a pH-dependent manner, as well as for bonding methods that avoid damaging the underlying post structure. A number of geometric posts designs are explored, with the goal of identifying post structures that provide the requisite surface area without a concurrent rise in fluidic resistance that promotes device failure. Initial proof-of-principle is shown by recovery of prepurified human genomic DNA (hgDNA), with real-world utility illustrated by purifying hgDNA from whole blood and demonstrating it to be PCR-amplifiable.     

The steady boundary value problem for charged incompressible fluids: PNP/Navier–Stokes systems

The initial-boundary value problem for the Poisson–Nernst–Planck/Navier–Stokes model was investigated in [J.W. Jerome, R. Sacco, Global weak solutions for an incompressible charged fluid with multi-scale couplings: initial-boundary-value problem, Nonlinear Anal. 71 (2009) e2487–e2497], where an existence theory was demonstrated, based upon Rothe’s method of horizontal lines. In this article, the steady case is considered, and the existence of a weak solution is established for the boundary-value problem. This solution satisfies a weak maximum principle for the concentrations relative to the boundary values. As noted in the above-mentioned citation, the model assumes significance because of its connection to the electrophysiology of the cell, including neuronal cell monitoring and microfluidic devices in biochip technology. The model has also been used in other applications, including electro-osmosis. The steady model is especially important in ion channel modeling, because the channel remains open for milliseconds, and the transients appear to decay on the scale of tens of nanoseconds.     

The N4 molecule and the N3 + ion

The possibility of the nitrogen molecule forming a stable dimer is investigated. Through ab initio calculations in an extended contracted-gaussian basis, it is demonstrated that N₄ in tetrahedral geometry and N₃ ⁺ in D _3h geometry are local minimum points on their respective internuclear potential energy surfaces. The N₄ molecule is considerably higher in energy than two ground-state N₂ molecules and some study of the barrier for N₄ decomposition has been made. The bond lengths and force constants for the two systems are shown to be similar to their hydrocarbon counterparts, C₄H₄ and C₃H₃ ⁺, tetrahedrane and cyclopropenyl cation. Other related systems are discussed as well.