Ion‐Selective Electrodes Based on Hydrophilic Ionophore‐Modified Nanopores

We report the synthesis and analytical application of the first Cu²⁺‐selective synthetic ion channel based on peptide‐modified gold nanopores. A Cu²⁺‐binding peptide motif (Gly‐Gly‐His) along with two additional functional thiol derivatives inferring cation‐permselectivity and hydrophobicity was self‐assembled on the surface of gold nanoporous membranes comprising of about 5 nm diameter pores. These membranes were used to construct ion‐selective electrodes (ISEs) with extraordinary Cu²⁺ selectivities, approaching six orders of magnitude over certain ions. Since all constituents are immobilized to a supporting nanoporous membrane, their leaching, that is a ubiquitous problem of conventional ionophore‐based ISEs was effectively suppressed.     

Semispectroscopic and quantitative structure-property relationship estimates of the equilibrium and vibrationally averaged structure and dipole moment of 1-buten-3-yne

Systematic quantum chemical calculations have been performed to obtain precise estimates of the equilibrium and vibrationally averaged molecular structure and electric dipole moment of vinylacetylene (VA, 1-buten-3-yne). Anharmonic (cubic and semi-diagonal quartic) MP2/cc-pVTZ force fields in normal coordinates were computed to account for anharmonic vibrational effects, including zero-point contributions to the rotational constants and the electric dipole moment. A simultaneous weighted least-squares structural refinement was performed, resulting in the best semispectroscopic estimate of the re structure of VA. The refinement was based on experimentally measured ground-state rotational constants of two isotopologs of VA corrected to equilibrium values using MP2/cc-pVTZ vibration-rotation interaction constants and all-electron CCSD(T)/aug-cc-pVTZ structural constraints. The semispectroscopic re structure of VA agrees excellently with the high-level CCSD(T)/aug-cc-pVTZ ab initio structure. The most dependable, CCSD(T)/cc-pVQZ//CCSD(T)/aug-cc-pVTZ equilibrium electric dipole moment of VA, in D, is mua= 0.4088, mub= 0.0004, and muc= 0. The vibrationally corrected a-component of 0.4214 D is in excellent agreement with one of the available experimental values. The present analysis shows that mub is negligible even after vibrational correction. A simple quantitative structure-property relationship (QSPR) model resulted in a highly similar estimate, 0.45 D, for the electric dipole moment of VA.     

Synthesis of D-seco-13α-Androst-5-ene Derivatives

Summary. 3β-Hydroxy-16,17-seco-13α-androsta-5,16-dien-17-al was obtained from 3β-acetoxyandrost-5-en-17-one in six steps with a Grob fragmentation as the key step. This seco-steroid, containing a formyl group and an unsaturated side-chain in a sterically favourable cis position, is a useful synthon for the synthesis of novel heterocycles condensed to the 3β-hydroxy-13α-androst-5-en-17-one skeleton.     

Lithiation of 2-(chloroaryl)-2-methyl-1,3-dioxolanes and application in synthesis of new ortho-functionalized acetophenone derivatives

2-(4-Chlorophenyl)-2-methyl-1,3-dioxolane 2a was lithiated ortho to the ketal group by treatment with butyllithium in THF at 0°C. Related 2-aryl-2-methyl-1,3-dioxolanes possessing a chlorine substituent at the meta position of the aryl group 2b,c were lithiated with butyllithium in THF at −78°C at the position between the two directing groups. The lithio species thus generated were treated with various electrophiles to give ortho-functionalized acetophenone derivatives.     

High-buffering capacity, hydrolytically stable, low-pI isoelectric membranes for isoelectric trapping separations

Hydrolytically stable, low-pI isoelectric membranes have been synthesized from low-pI ampholytic components, poly(vinyl alcohol), and a bifunctional cross-linker, glycerol-1,3-diglycidyl ether. The low-pI ampholytic components used contain one amino group and at least two weakly acidic functional groups. The acidic functional groups are selected such that the pI value of the ampholytic component is determined by the pK(a) values of the acidic functional groups. When the concentration of the ampholytic component incorporated into the membrane is higher than a required minimum value, the pI of the membrane becomes independent of variations in the actual incorporation rate of the ampholytic compound. The new, low-pI isoelectric membranes have been successfully used as anodic membranes in isoelectric trapping separations with pH < 1.5 anolytes and replaced the hydrolytically less stable polyacrylamide-based isoelectric membranes. The new low-pI isoelectric membranes have excellent mechanical stability, low electric resistance, good buffering capacity, and long life time, even when used with as much as 50 W power and current densities as high as 33 mA/cm(2) during the isoelectric trapping separations.     

Vector algebra and molecular symmetry: a tribute to Professor Josiah Willard Gibbs

Vector algebra, as developed by Josiah Willard Gibbs, is much simpler than matrix or tensor algebra, therefore, it is more suitable to introduce the students of chemistry into the wonderful world of molecular symmetry. A program based on elementary vector algebra has been written to determine all symmetry elements and symmetry operations of rigid molecular structures. The program also contains data for 57 point groups common in chemistry. Therefore, it automatically supplies the particular point group to which the structure belongs. Since the locations of the nuclei related to the symmetry elements are also revealed by the program, even the detailed notation of the framework group of the molecular structure can be deduced. The program can be a great help in determining the symmetries of the normal modes of vibration, too.     

A functional equation arising from ranked additive and separable utility

All strictly monotonic solutions of a general functional equation are determined. In a particular case, which plays an essential role in the axiomatization of rank-dependent expected utility, all nonnegative solutions are obtained without any regularity conditions. An unexpected possibility of reduction to convexity makes the present proof possible.

     

A practical prioritization by multi-level group decision support

Military capability is proposed to be defined according to the DYNPOT scoring method. Multiobjective resource allocation of shared resources by group decision-making can combine analytic and qualitative modeling. Recently it has been pointed out that the goal programming model is superior to other models though it remained to be answered how to take into account hierarchy of decision makers (and objectives) (Stummer and Vetschera in Cent Eur J Oper Res 11:3–260, 2003). In this article it is tried to present, that the quantitative model can be easily adapted to the qualitative STT/QFD model of objectives of top-level group of decision-makers. The subsequent phases of the qualitative and the analytic solution of a multiobjective cooperative resource allocation problem can be applied within the group decision-making framework of defence requirements capability-based planning.     

AN ERDőS-SZEKERES TYPE PROBLEM IN THE PLANE

Periodica Mathematica Hungarica -