Theory of chromatography of linear and cyclic polymers with functional groups

We discuss the chromatographic behavior of linear polymers and rings having specific (functional) adsorption-active groups. Functionalized eight-shaped, daisy-like and theta-shaped macromolecules are considered as well. By using a model of an ideal chain with point-type defects in a slit-like pore we derive equations for the distribution coefficient covering all modes of chromatography of functionalized polymers of any molar mass in both narrow and wide pores. Additionally simple approximate formulae are obtained for a number of important modes of chromatography; chromatograms are simulated for model mixtures of polydisperse non-functional and functional polymers. By using the theory we analyze separation of polymers by molar mass, functionality and topology. Although there is a principal possibility to use adsorption chromatography or size-exclusion chromatography (SEC), we conclude that the liquid chromatography at the critical condition (LCCC) is especially efficient for separation of polydisperse polymers by both functionality and topology. The theory predicts that functionalized linear and cyclic polymers can be separated from each others by LCCC even better than non-functionalized ones. The LCCC behavior of some other types of polymers such as comb-like and semicyclic ones is discussed as well.     

Ion mobility mass spectrometry analysis of human glycourinome

Complex carbohydrates are macromolecules biosynthesized in nontemplate-type processes, bearing specific glycoepitopes involved in crucial recognition processes such as cell differentiation and cell-cell interactions. Chemical structure of single components in complex mixtures can be analyzed by mass spectrometry for determination of the size and sequence of monosaccharides involved, branching patterns, and substitution by fucose and sialic acids. For de novo identification of glycoforms in human urinome containing N- and O-free and amino acid-linked oligosaccharides, a novel method of ion mobility tandem mass spectrometry followed by computer-assisted assignment is described. Distinct patterns of ions nested specifically by their m/z values and their drift time are observed by IMS-MS. An additional peak capacity for identification of time-separated m/z values in the IMS TOF MS mode for differentiation of singly, doubly, and triply charged molecular ion species by ion mobility separation contributes to significant reduction of carbohydrate complexity in a given mass window. Profiling of glycoforms from human urinome represents a highly efficient approach for biomarker discovery and differential glycotarget identification, demonstrating potential for diagnosis of human diseases, as for congenital disorders of glycosylation.     

Liquid chromatography of theta-shaped and three-armed star poly(tetrahydrofuran)s: theory and experimental evidence of topological separation

A theoretical background is provided for the methods of the analysis and topological separation of complex macrocyclic polymers by means of size exclusion chromatography (SEC), liquid adsorption chromatography, and liquid chromatography at the critical condition. We focus on a particular problem of the separation of theta-shaped polymers from its three-armed star analogues. Based on the theory, we simulate chromatograms for model mixtures of polydisperse theta- and star-polymers and analyze conditions for good separation of these polymers by topology. A theory is compared with the behavior of star- and theta-shaped poly(THF)s in size exclusion and interactive chromatography, and a good qualitative agreement between theory and experiment is observed. In particular, it is shown that in both SEC and interactive chromatography theta-polymers elute after the corresponding stars of the same molar mass. According to theory and experiment, chromatography under the critical and near-critical interaction conditions is especially promising for the separation of polydisperse macrocyclic polymers from their linear or branched analogues.     

Advanced Process Simulation of Solidification and Melting

At some stage in the production of every metal part or product, the metal material has been melted and solidified to form the primary or final shape as well as the as-cast structure. Quantitative prediction and control of solidification and melting has been, and remains, the most critical issue in the metallurgical industry. Example questions currently raised by the Austrian metallurgical industry, which is one of the key economic sectors of this country, are as follows: in thin-slab casting, how does the solid shell form and interact with turbulent flow? How can the electro-slag-remelting (ESR) process be better understood and controlled (stabilized)? How can metallurgical imperfections (macrosegregation, porosity, non-metallic inclusion, surface crack, etc.) in castings be predicted and minimized? Therefore, a Christian-Doppler laboratory—Advanced Process Simulation of Solidification and Melting was established in July 2011 with the final goal to address the questions mentioned above. This article reports on some progresses.     

Process Simulation for the Metallurgical Industry: New Insights into Invisible Phenomena

In order to demonstrate how advanced process simulation can help to understand metallurgical process details and thus to improve industrial productivity, a number of examples are shown and discussed. The paper covers recent simulation results gained at the Chair of Simulation and Modeling of Metallurgical Processes, namely (i) the flow and shell formation in thin slap casting of steel, (ii) multiphase flow and magneto-hydrodynamic during Electro-Slag-Remelting, (iii) mold filling, surface wave dissipation and solidification during horizontal centrifugal casting of rolls, and (iv) forced and natural convection during electro-refining of copper in an industrial-size tankhouse cell.     

Numerical Investigation of Shell Formation in Thin Slab Casting of Funnel-Type Mold

The key issue for modeling thin slab casting (TSC) process is to consider the evolution of the solid shell including fully solidified strand and partially solidified dendritic mushy zone, which strongly interacts with the turbulent flow and in the meantime is subject to continuous deformation due to the funnel-type mold. Here an enthalpy-based mixture solidification model that considers turbulent flow [Prescott and Incropera, ASME HTD, 1994, vol. 280, pp. 59–69] is employed and further enhanced by including the motion of the solidifying and deforming solid shell. The motion of the solid phase is calculated with an incompressible rigid viscoplastic model on the basis of an assumed moving boundary velocity condition. In the first part, a 2D benchmark is simulated to mimic the solidification and motion of the solid shell. The importance of numerical treatment of the advection of latent heat in the deforming solid shell (mushy zone) is specially addressed, and some interesting phenomena of interaction between the turbulent flow and the growing mushy zone are presented. In the second part, an example of 3D TSC is presented to demonstrate the model suitability. Finally, techniques for the improvement of calculation accuracy and computation efficiency as well as experimental evaluations are also discussed.     

Magnetic mutually inductive transducer of the distance to the surface of a ferromagnetic object

The possibility of using a mutually inductive transducer as a measuring transducer of the beats of a round cylindrical surface in order to measure the axis misalignment of welded joints was investigated. The optimal design values of the transducer were selected based on the results of physical and mathematical simulations of the transducer’s magnetic field interaction with a ferromagnetic surface; the influence of the edge effect was estimated as well.     

Theory of chromatography of ring-shaped block copolymers

A theory is developed for describing liquid chromatography of ring diblock and multiblock copolymers. The chromatographic behavior of ring block copolymers at different adsorption interactions is analyzed theoretically and compared with that of linear block copolymers; typical chromatograms are simulated by using the theory. In particular, it is shown that under the critical interaction condition for one block the chromatographic retention of a ring diblock copolymer is dependent of the length of the ‘critical’ block; this behavior differs qualitatively from that of a linear diblock copolymer. Ring copolymers are always more retained than linear ones, therefore such copolymers can be separated. Especially good separation of heterogeneous ring and linear block copolymers is predicted at near-critical interaction conditions. According to the theory, ring diblocks and multiblocks can be separated as well, if one component of a copolymer is adsorbing, while the other one is not adsorbing.