In situ enrichment of phosphopeptides on MALDI plates functionalized by reactive landing of zirconium(IV)-n-propoxide ions

We report substantial in situ enrichment of phosphopeptides in peptide mixtures using zirconium oxide coated plates for detection by MALDI-TOF mass spectrometry. The novel feature of this approach rests on the specific preparation of zirconium oxide coatings using reactive landing on stainless steel support of gas-phase positive ions produced by electrospray of zirconium(IV)-n-propoxide solutions in 1-propanol. Reactive landing was found to produce durable functionalized surfaces for selective phosphopeptide capture and desorption-ionization by MALDI. Enrichment factors on the order of 20-90 were achieved for several monophosphorylated peptides relative to abundant nonphosphorylated peptides in tryptic digests. We demonstrate the ability of the zirconium oxide functionalized MALDI surfaces to facilitate detection of enriched phosphopeptides in mid-femtomole amounts of alpha-casein digests per MALDI spot.     

“Molded” porous polymer monoliths: A novel format for capillary gas chromatography stationary phases

Highly permeable monolithic columns have been prepared directly within capillaries of various internal diameters by the in situ polymerization of high purity divinylbenzene, characterized, and used as novel stationary phases for gas‐solid chromatography. The chromatographic properties of these columns are demonstrated by the efficient separation of mixtures of volatile organic compounds as well as their aqueous solutions.     

Nanoporous Polymers for Hydrogen Storage

The design of hydrogen storage materials is one of the principal challenges that must be met before the development of a hydrogen economy. While hydrogen has a large specific energy, its volumetric energy density is so low as to require development of materials that can store and release it when needed. While much of the research on hydrogen storage focuses on metal hydrides, these materials are currently limited by slow kinetics and energy inefficiency. Nanostructured materials with high surface areas are actively being developed as another option. These materials avoid some of the kinetic and thermodynamic drawbacks of metal hydrides and other reactive methods of storing hydrogen. In this work, progress towards hydrogen storage with nanoporous materials in general and porous organic polymers in particular is critically reviewed. Mechanisms of formation for crosslinked polymers, hypercrosslinked polymers, polymers of intrinsic microporosity, and covalent organic frameworks are discussed. Strategies for controlling hydrogen storage capacity and adsorption enthalpy via manipulation of surface area, pore size, and pore volume are discussed in detail.

     

Use of branched aliphatic linkers for the preparation of selective chiral media for the HPLC separation of enantiomers

Summary Highly branched aliphatic molecules have been used for the first time as tethers in the preparation of polymeric chiral stationary phases. Attachment of a specifically designed chiral selector to organic porous polymer beads through a branched linker substantially increases the enantioselectivity compared to that of the equivalent separation medium with a traditional linear tether. Received: 31 March 1998/Revised version: 27 May 1998/Accepted: 27 May 1998     

13C n.m.r. study of the structure of poly(aspartic acid)

From hydrolysis of the product of thermal polycondensation of aspartic acid, poly(succinimide), under various conditions, a series of samples of thermal poly(aspartic acid) was obtained. These polymers differed by molecular mass and, from n.m.r. spectral evidence, by the contents of α and β peptide bonds, depending mostly on the pH of hydrolsysis. The contents of α and β bonds found were further confirmed by analysis of the n.m.r. spectra of the complex of poly(aspartic acid) with Co(II). Also, spectra of poly(aspartic acid) obtained by debenzylation of poly(β-benzyl-l-aspartate) described in our previous work were analyzed in greater detail. A comparison of racemic and optically pure polymers has shown that the n.m.r. spectra are only slightly affected by stereoregularity, and that stereoregularity is not the cause of the splitting of the various carbon bonds. Analysis of the complicated structure of the spectra, mainly of the carbonyl group, leads us to the conclusion that the distribution of the α and β bonds is random in all the polymers studied.     

Interoperable domain‐specific languages families for code generation

This paper has been motivated by experience gained with specification and code generation of control elements for a software component platform and general‐purpose programming language like Java and C. The problem to be addressed is two‐fold: first, several domain‐specific languages (DSL) are to be employed to express different element concerns (architecture, deployment context, code pattern) and second, porting to another general‐purpose language should avoid modification of the specification and related code generation process as much as possible. In both respects, the classical template‐based code generation technique proved to be inflexible, requiring the code generator to be blurred with ad hoc encoded DSL facets. The paper addresses the problem by introducing the concept of interoperable DSL family. Each member of the family is built around its core language, which can be further specialized by embedding into a target programming language. Interoperability of these DSLs is achieved at the level of abstract syntax trees (ASTs) with help of queries. As a proof of the concept, we have implemented the queries via the AST transformation rules of the Stratego/XT framework. In the evaluation, we provide a comparison with the original template‐based implementation, which clearly indicates the DSL family and AST transformation benefits. We also provide examples of application areas where the concept of interoperable DSL family can be employed (and also indicate how this can be accomplished). Copyright © 2012 John Wiley & Sons, Ltd.     

Remotely detected NMR for the characterization of flow and fast chromatographic separations using organic polymer monoliths

An application of remotely detected magnetic resonance imaging is demonstrated for the characterization of flow and the detection of fast, small molecule separations within hypercrosslinked polymer monoliths. The hyper-cross-linked monoliths exhibited excellent ruggedness, with a transit time relative standard deviation of less than 2.1%, even after more than 300 column volumes were pumped through at high pressure and flow. Magnetic resonance imaging enabled high-resolution intensity and velocity-encoded images of mobile phase flow through the monolith. The images confirm that the presence of a polymer monolith within the capillary disrupts the parabolic laminar flow profile that is characteristic of mobile phase flow within an open tube. As a result, the mobile phase and analytes are equally distributed in the radial direction throughout the monolith. Also, in-line monitoring of chromatographic separations of small molecules at high flow rates is shown. The coupling of monolithic chromatography columns and NMR provides both real-time peak detection and chemical shift information for small aromatic molecules. These experiments demonstrate the unique power of magnetic resonance, both direct and remote, in studying chromatographic processes.     

Chemical Composition and Mechanical Characteristic of Nitrogen Ion Beam Mixed Carbon Nanolayer

Ion beam methods for modification of nanohardness of surface nanolayers of the titanium alloy Ti6AI4V were applied. After deposition of carbon nanolayers by electron beam evaporation, the ion implantation of nitrogen into samples was carried out. The chemical composition of the modified surface area was investigated by AES （auger electron spectroscopy）. The nanohardness of resulted ion beam modified surface nanolayers were investigated by nanoindentation testing. The measured concentration profiles indicate the atomic mixing of carbon into the substrate. It was found that the modified samples had a markedly higher nanohardness than the unmodified samples. The increased nanohardness is attributed to the newly created phases in the surface area.