Pointwise absolutely convergent series of operators and related classes of Banach spaces

We study classes of operators represented as a pointwise absolutely convergent series of simpler ones, starting with rank 1 operators. In this short note we address the question, how far the repetition of this procedure can lead.     

Correction to: Continuity in the Parameter for the Solutions of One-Dimensional Boundary-Value Problems for Differential Systems of Higher Orders in Slobodetskii Spaces

Ukrainian Mathematical Journal - The authors’ names should read H. O. Masliuk and V. A. Mikhailets.     

Barothermal Diels-Alder functionalization of multi-walled carbon nanotubes

Abstract

Multi-walled carbon nanotubes (MWCNTs) have an ordered geometric structure, large specific surface area, prominent electrical conductivity, and unique mechanical properties. They are nontoxic and can be used in biomedicine. Physical and surface chemical characteristics of MWCNTs should be tuned to that required to improve certain properties and obtain a variety of functional materials. We modified the MWNTs by using the barothermal Diels-Alder reaction with dienophiles, p-benzoquinone, fumaronitrile, and maleimide, to address this issue. The prepared MWCNTs were studied by SEM-EDX, nitrogen adsorption porometry, ATR FTIR, and thermal analysis. Results showed that both separate and conjugated C?=?C bonds at the edge and outer/inner surface of walls could react with dienophiles. The grafted groups are separated by the temperature on weak (low-temperature) and strong (high-temperature) chemisorbed forms; they are detached at temperatures below and above 350?°C, correspondingly. Thermal analysis shows that up to 5% of the carbon atoms are involved in the [4?+?2] cycloaddition. The high-temperature forms of the grafted groups under extreme heating can be involved in the retro-Diels-Alder reaction that breaks six-membered rings, producing a dienophile.     

Direct Photocontrol of Peptidomimetics: An Alternative to Oxygen‐Dependent Photodynamic Cancer Therapy

Conventional photodynamic treatment strategies are based on the principle of activating molecular oxygen in situ by light, mediated by a photosensitizer, which leads to the generation of reactive oxygen species and thereby causes cell death. A diarylethene‐derived peptidomimetic is presented that is suitable for photodynamic cancer therapy without any involvement of oxygen. This light‐sensitive molecule is not a mediator but is itself the cytotoxic agent. As a derivative of the cyclic amphiphilic peptide gramicidin S, the peptidomimetic exists in two thermally stable photoforms that are interconvertible by light of different wavelengths. The isomer generated by visible light shows much stronger toxicity against tumor cells than the UV‐generated isomer. First in vivo applications are demonstrated on a tumor animal model to illustrate how the peptidomimetic can be administered in the less toxic form and then activated locally in a solid tumor by visible light.     

Structure and electrochemical properties for complexes of nitrocompounds with inorganic ions: A theoretical approach

Reduction and oxidation (redox) reactions are widely used for removal of nitrocompounds from contaminated soil and water. Structures and redox properties for complexes of nitrocompounds, such as 2,4,6‐trinitrotoluene (TNT), 2,4‐dinitrotoluene (DNT), 2,4‐dinitroanisole (DNAN), and 5‐nitro‐2,4‐dihydro‐3H?1,2,4‐triazol‐3‐one (NTO), with common inorganic ions (Na⁺, Cl^?, ) were investigated at the SMD(Pauling)/PCM(Pauling)/MPWB1K/TZVP level of theory. Atoms in molecules (AIM) theory was applied to analyze the topological properties of the bond critical points involved in the interactions between the nitrocompounds and the ions. Topological analyses show that intermolecular interactions of the types O(N)…Na⁺, C‐H…Cl^?( ), and C…Cl^?( ) may be discussed as noncovalent closed‐shell interactions, while N‐H···Cl^?( ) hydrogen bonds are partially covalent in nature. Complexation causes significant decrease of redox activity of the nitrocompounds. Analysis of the reduction potentials of the complexes obtained through application of the Pourbaix diagram of an iron/water system revealed that sodium complexes of NTO might be reduced by metallic iron. © 2016 Wiley Periodicals, Inc.     

Are the reduction and oxidation properties of nitrocompounds dissolved in water different from those produced when adsorbed on a silica surface? A DFT M05‐2X computational study

The reduction and oxidation properties of four nitrocompounds (trinitrotoluene [TNT], 2,4‐dinitrotoluene, 2,4‐dinitroanisole, and 5‐nitro‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one [NTO]) dissolved in water as compared with the same properties for compounds adsorbed on a silica surface were studied. To consider the influence of adsorption, cluster models were developed at the M05/tzvp level. A hydroxylated silica (001) surface was chosen to represent a key component of soil. The PCM(Pauling) and SMD solvation models were used to model water bulk influence. The following properties were analyzed: electron affinity, ionization potential, reduction Gibbs free energy, oxidation Gibbs free energy, and reduction and oxidation potentials. It was found that adsorption and solvation decrease gas phase electron affinity, ionization potential, and Gibbs free energy of reduction and oxidation, and thus, promote redox transformation of nitrocompounds. However, in case of solvation, the changes are more significant than for adsorption. This means that nitrocompounds dissolved in water are easier to transform by reduction or oxidation than adsorbed ones. Among the considered compounds, TNT was found to be the most reactive in an electron attachment process and the least reactive for an electron detachment transformation. During ionization, a deprotonation of adsorbed NTO was found to occur. © 2015 Wiley Periodicals, Inc.     

Catenation control in the two-dimensional coordination polymers based on tritopic carboxylate linkers and azamacrocyclic nickel(II) complexes

Four new coordination polymer frameworks, namely [(NiL(1))(3)(BTB)(2)]·6H(2)O, [(NiL(2))(3)(BTB)(2)]·6H(2)O, [(NiL(3))(3)(BTB)(2)]·6H(2)O and [(NiL(2))(3)(BTC)(2)]·10.25H(2)O (L(1) = 1,4,8,11-tetraazacyclotetradecane, L(2) = 3-methyl-1,3,5,8,12-pentaazacyclotetradecane, L(3) = 3,10-dimethyl-1,3,5,8,10,12-hexaazacyclotetradecane, BTC(3-) = benzene-1,3,5-tricarboxylate, BTB(3-) = 4,4',4'-benzene-1,3,5-triyl-tribenzoate) were prepared in water-N,N-dimethylformamide solutions. The molecular and crystal structures of these compounds are compared to the related coordination polymers formed by nickel(II) macrocyclic cations to examine the effect of carboxylate linker size on the framework architecture. Luminescent properties of the complexes based on the BTB(3-) bridging ligand are also discussed.     

Theoretical study of ionization and one‐electron oxidation potentials of N‐heterocyclic compounds

A number of density functionals was utilized to predict gas‐phase adiabatic ionization potentials (IPs) for nitrogen‐rich heterocyclic compounds. Various solvation models were applied to the calculation of difference in free energies of solvation of oxidized and reduced forms of heterocyclic compounds in acetonitrile (AN) for correct reproduction of their standard oxidation potentials. We developed generally applicable protocols that could successfully predict the gas‐phase adiabatic ionization potentials of nitrogen‐rich heterocyclic compounds and their standard oxidation potentials in AN. This approach is supported by a MPW1K/6‐31+G(d) level of theory which uses SMD(UA0) approximation for estimation of solvation energy of neutral molecules and PCM(UA0) model for ionized ones. The mean absolute derivation (MAD) and root mean square error (RMSE) of the current theoretical models for IP are equal to 0.22 V and 0.26, respectively, and for oxidation potentials MAD = 0.13 V and RMSE = 0.17. © 2013 Wiley Periodicals, Inc.     

Elucidation of artefacts in proton transfer reaction time‐of‐flight mass spectrometers

We present an effective procedure to differentiate instrumental artefacts, such as parasitic ions, memory effects, and real trace impurities contained in inert gases. Three different proton transfer reaction mass spectrometers were used in order to identify instrument‐specific parasitic ions. The methodology reveals new nitrogen‐ and metal‐containing ions that up to date have not been reported. The parasitic ion signal was dominated by [N₂]H⁺ and [NH₃]H⁺ rather than by the common ions NO⁺ and O₂⁺. Under dry conditions in a proton transfer reaction quadrupole interface time‐of‐flight mass spectrometer (PTR‐QiTOF), the ion abundances of [N₂]H⁺ were elevated compared with the signals in the presence of humidity. In contrast, the [NH₃]H⁺ ion did not show a clear humidity dependency. On the other hand, two PTR‐TOF1000 instruments showed no significant contribution of the [N₂]H⁺ ion, which supports the idea of [N₂]H⁺ formation in the quadrupole interface of the PTR‐QiTOF. Many new nitrogen‐containing ions were identified, and three different reaction sequences showing a similar reaction mechanism were established. Additionally, several metal‐containing ions, their oxides, and hydroxides were formed in the three PTR instruments. However, their relative ion abundancies were below 0.03% in all cases. Within the series of metal‐containing ions, the highest contribution under dry conditions was assigned to the [Fe(OH)₂]H⁺ ion. Only in one PTR‐TOF1000 the Fe⁺ ion appeared as dominant species compared with the [Fe(OH)₂]H⁺ ion. The present analysis and the resulting database can be used as a tool for the elucidation of artefacts in mass spectra and, especially in cases, where dilution with inert gases play a significant role, preventing misinterpretations.