Electrochemistry of Novel Phthalocyanines Bearing 1,2,4 Triazole Groups

The phthalonitrile (3) and triazole substituted metallo phthalocyanines (MPc) (4–7) were prepared. The novel compounds were characterized with spectroscopic data. Electrochemical analyses of metallophthalocyanines (4–7) bearing triazole substituents were performed to investigate redox activity of phthalocyanines (Pcs) ring. While incorporation of Ni²⁺ and Cu²⁺ cations in the Pc core only influenced peak positions of Pc ring processes, Co²⁺ and Cl^1?Fe³⁺ cations of CoPc and FePc gave extra redox couples to the Pc based ones. Releasing the axial Cl^1? anion on Fe³⁺ cation of FePc during the reduction reactions complicated the redox responses. Redox reactions of Co²⁺ and Fe³⁺ metal centers also considerable influenced spectral and color responses of these complexes.     

Distribution of averages of Ramanujan sums

The average value of a certain normalization of Ramanujan sums is determined in terms of Bernoulli numbers and odd values of the Riemann zeta function. The distribution of values and limiting behavior of such a normalization are then studied along subsets of Beurling type integers with positive density and sequences of moduli with constraints on the number of distinct prime factors.     

Low‐Temperature,Rapid Copolymerization of Acrylic Acid and Sodium Acrylate in Water

Regulating the aqueous polymerization of acrylic acid (AA) is a major opportunity for future materials design, requiring the development of scalable, industry‐oriented procedures that afford modest molar mass and dispersity control without long reaction times and environmentally demanding conditions. To address these challenges, this report presents the rapid copolymerization of aqueous mixtures of AA and sodium acrylate using an inexpensive and scalable protocol based on alkyl iodides/sodium iodide as mediators in water. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1414–1419     

7‐Nitro­indazole

The title compound, C₇H₅N₃O₂, is an inhibitor of nitric oxide synthase and mono­amine oxidase. The N1H tautomer crystallized as a dimer and adopts a planar conformation assisted by intramolecular hydrogen bonding.     

Diophantine approximation with mild divisibility constraints

Given an irrational number α and a sequence B of coprime positive integers with the sum of inverses convergent, we investigate the problem of finding small values of nα, with n B-free.     

Pair correlation of torsion points on elliptic curves

We prove the existence of the pair correlation measure associated to torsion points on the real locus E(R) of an elliptic curve E and provide an explicit formula for the limiting pair correlation function.     

Engineered 3D tissue models for cell-laden microfluidic channels

Delivery of nutrients and oxygen within three-dimensional (3D) tissue constructs is important to maintain cell viability. We built 3D cell-laden hydrogels to validate a new tissue perfusion model that takes into account nutrition consumption. The model system was analyzed by simulating theoretical nutrient diffusion into cell-laden hydrogels. We carried out a parametric study considering different microchannel sizes and inter-channel separation in the hydrogel. We hypothesized that nutrient consumption needs to be taken into account when optimizing the perfusion channel size and separation. We validated the hypothesis by experiments. We fabricated circular microchannels (r = 400 μm) in 3D cell-laden hydrogel constructs (R = 7.5 mm, volume = 5 ml). These channels were positioned either individually or in parallel within hydrogels to increase nutrient and oxygen transport as a way to improve cell viability. We quantified the spatial distribution of viable cells within 3D hydrogel scaffolds without channels and with single- and dual-perfusion microfluidic channels. We investigated quantitatively the cell viability as a function of radial distance from the channels using experimental data and mathematical modeling of diffusion profiles. Our simulations show that a large-channel radius as well as a large channel to channel distance diffuse nutrients farther through a 3D hydrogel. This is important since our results reveal that there is a close correlation between nutrient profiles and cell viability across the hydrogel. Young Seok Song and Richard L. Lin have contributed equally to this contribution     

Nanoporous structures on ZnO thin films

Porous structures were formed on ZnO thin films which were grown by an electrochemical deposition (ECD) method. The growth processes were carried out in a solution of dimethylsulfoxide (DMSO) zinc perchlorate, Zn(ClO₄)₂, at 120 ^°C on indium tin oxide (ITO) substrates. Optical and structural characterizations of electrochemically grown ZnO thin films have shown that the films possess high (0002) c$c$-axis orientation, high nucleation, high intensity and low FWHM of UV emission at the band edge region and a sharp UV absorption edge. Nanoporous structures were formed via self-assembled monolayers (SAMs) of hexanethiol (C₆SH) and dodecanethiol (C₁₂SH). Scanning electron microscope (SEM) measurements showed that while a nanoporous structure (pore radius 20 nm) is formed on the ZnO thin films by hexanathiol solution, a macroporous structure (pore radius 360 nm) is formed by dodecanethiol solution. No significant variation is observed in X-ray diffraction (XRD) measurements on the ZnO thin films after pore formation. However, photoluminescence (PL) measurements showed that green emission is observed as the dominant emission for the macroporous structures, while no variation is observed for the thin film nanoporous ZnO sample.