Atomic spectrometry and atomic mass spectrometry in bioanalytical chemistry

Abstract

Atomic spectrometry and atomic mass spectrometric (MS) techniques have been playing crucial roles in the field of biosciences. They detect elements with relatively high sensitivities and are thus applicable to a wide range of analytical targets. In the past decade, determination of bio-relevant metallic elements continues to be of interest, while particularly noteworthy are methods developed for small molecules, peptides, proteins, nucleic acids and even cells that well exploited the bio-analytical strengths of atomic spectrometry and atomic MS, either in a direct or indirect manner. Quantitation, as well as speciation and imaging analyses are all involved. The present review aims to assimilate recent advances in bio-analysis utilizing atomic spectrometry and atomic MS, primarily covering the period of 2013–2018, in an attempt to provide readers insight into the developing trends of this research frontier. Followed by concluding remarks and perspectives, the applications are divided into the following four catalogs: (i) toxicologically important metal-containing species, with an emphasis on quantitative and imaging analysis; (ii) quantitation of biomolecules using naturally occurring heteroatoms; (iii) exogenous metal ion or nanoparticle tagging-based strategies in bioassays; and (iv) label-free detection of biomolecules.     

On the critical cases of linearly coupled Choquard systems

We study the existence and nonexistence results for a class of linearly coupled Choquard system in critical cases.     

Fabrication techniques for high-quality optical fibers

Various vapor deposition processes are being used to manufacture optical fibers in different parts of the world. This paper provides an introduction to the common vapor deposition technology, reviews the different processes, and compares them in terms of performance and cost potential.     

MOLCAS 7: The Next Generation

Some of the new unique features of the MOLCAS quantum chemistry package version 7 are presented in this report. In particular, the Cholesky decomposition method applied to some quantum chemical methods is described. This approach is used both in the context of a straight forward approximation of the two‐electron integrals and in the generation of so‐called auxiliary basis sets. The article describes how the method is implemented for most known wave functions models: self‐consistent field, density functional theory, 2nd order perturbation theory, complete‐active space self‐consistent field multiconfigurational reference 2nd order perturbation theory, and coupled‐cluster methods. The report further elaborates on the implementation of a restricted‐active space self‐consistent field reference function in conjunction with 2nd order perturbation theory. The average atomic natural orbital basis for relativistic calculations, covering the whole periodic table, are described and associated unique properties are demonstrated. Furthermore, the use of the arbitrary order Douglas‐Kroll‐Hess transformation for one‐component relativistic calculations and its implementation are discussed. This section especially focuses on the implementation of the so‐called picture‐change‐free atomic orbital property integrals. Moreover, the ElectroStatic Potential Fitted scheme, a version of a quantum mechanics/molecular mechanics hybrid method implemented in MOLCAS, is described and discussed. Finally, the report discusses the use of the MOLCAS package for advanced studies of photo chemical phenomena and the usefulness of the algorithms for constrained geometry optimization in MOLCAS in association with such studies. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010     

Redox-Initiated Grafting of Acrylic Monomers onto Poly(vinyl Alcohol)

Loss of capacity of magnetic micro ion-exchange resins has been suggested to be caused by cleavage of unstable linkages formed during the graft polymerization reaction. The nature of the grafting process was investigated by using a series of model compounds having the same structural features as the glutaraldehyde-crosslinked poly(vinyl alcohol) core matrix. These compounds were then subjected to hydrogen peroxide oxidation, followed by the addition of monomer in the presence of iron(II). The identity and extent of peroxidation of the intermediate compounds was determined. In each of the peroxidation reactions the tertiary acetal hydrogen was oxidized to a hydroperoxy derivative. Some of these derivatives were able to dimerize to form peroxy compounds. The reactions occurred rapidly at room temperature when an acetal compound was shaken with hydrogen peroxide. Good yields could be obtained by precipitation of the sodium salts of the hydroperoxides. The hydroperoxy derivatives were shown to initiate polymerization of methyl acrylate, acrylic acid, and acrylamide when in the presence of iron(II).     

Using a fully coupled flow and geomechanical simulator to model injection into heavy oil reservoirs

In this paper, the geomechanical factors that may affect injection processes in heavy oil recovery are investigated. To accurately capture the geomechanical effects, we employed a numerical formulation that allows fully coupling of nonlinear geomechanical deformation and multicomponent porous media flows. Two salient features of this new coupling formulation are the following: (1) all flow and geomechanical equations are solved implicitly in one single matrix equation, and (2) it allows reuse of matrices from both a traditional fully implicit multicomponent reservoir simulator and a nonlinear geomechanics simulator. The former feature ensures stable coupling between the reservoir flow and geomechanics, and the latter significantly reduces the programming work. Numerical examples are given to demonstrate the accuracy and convergence performance of the new formulation. The proposed formulation is then applied to model injection into heavy oil reservoirs. The numerical investigation revealed that geomechanical factors, such as in situ stress anisotropy and the uneven deformation of reservoir rock and attached impermeable rock, can result in skewed or nonuniform plastic strain and, hence, alter the sweep of the injected fluid. Coupled geomechanics simulation also gives rather different transient pressure response from that of uncoupled simulation. Copyright © 2012 John Wiley & Sons, Ltd.     

Photoinduced Cleavage and Hydrolysis of o‐Nitrobenzyl Linker and Covalent Linker Immobilization in Gelatin Methacryloyl Hydrogels

Light‐induced release systems can be triggered remotely and are of interest for many controlled release applications due to the possibility for spatio‐temporal release control. In this study a biotin‐functionalized photocleavable macromer is incorporated with an o‐nitrobenzyl moiety into gelatin methacryloyl(‐acetyl) hydrogels via radical cross‐linking. Stronger immobilization of streptavidin‐coupled horseradish peroxidase occurs in linker‐functionalized hydrogels compared to pure gelatin methacryloyl(‐acetyl) hydrogels, and a controlled release of the streptavidin conjugate upon UV‐irradiation is possible. Liquid chromatography coupled to mass spectrometry (LC‐MS) analysis of aqueous linker solutions allows the identification of the main cleavage products and the cleavage kinetics. Thus, it is shown that a significant hydrolysis of the linker occurs at 37 °C. Nevertheless the system reported here is a promising controlled release scaffold for proteins and application in tissue engineering, if background releases of the immobilized drug are tolerable.