Review of centrifugal liquid-liquid chromatography using aqueous two-phase solvent (ATPS) systems: Its scale-up and prospects for the future production of high-value biologics

The future challenges in bioprocessing include developing new downstream processes for the purification and manufacture of the protein based medicines of the future to relieve the predicted bottleneck being produced by increasingly high titres from fermentation processes. This review looks at the recent developments in centrifugal liquid-liquid partition chromatography using aqueous two-phase solvent (ATPS) systems, a gentle host medium for biologics, and the prospect for scale-up and eventual manufacture of high value pharmaceutical products

Solitons in the Calogero-Sutherland Collective-Field Model

In the Bogomol'nyi limit of the Calogero-Sutherland collective-field model we find static-soliton solutions. The solutions of the equations of motion are moving solitons, having no static limit for \l>1. They describe holes and lumps, depending on the value of the statistical parametar \l.Comment: minor correction

On the oxide formation on stainless steels AISI 304 and incoloy 800H investigated with XPS

The influence of cold work on the initially formed oxide layer on the stainless steels AISI 304 and Incology 800H has been studied by XPS. Oxidations were performed at pressures of 10-6-10-4 Pa and temperatures of 300–800 K. All samples showed a similar oxidation behaviour. The oxidation rates of iron and chromium are of the same order of magnitude at temperatures below 650 K. Subsequent oxidation results in an iron oxide on top of a chromium oxide layer. At temperatures above 650 K the metal surface becomes enriched in chromium, which is preferentially oxidized at these temperatures and pressures. Even prolonged oxidation does not result in an iron-rich oxide surface. Nickel has never been found in its oxidized form. The binding energy of oxygen, in the various oxide layers, is independent of the extent of oxidation and is 530.6 eV

Exact spin-orbital separation in a solvable model in one dimension

A one-dimensional model of coupled spin-1/2 spins and pseudospin-1/2 orbitals with nearest-neighbor interaction is rigorously shown to exhibit spin-orbital separation by means of a non-local unitary transformation. On an open chain, this transformation completely decouples the spins from the orbitals in such a way that the spins become paramagnetic while the orbitals form the soluble XXZ Heisenberg model. The nature of various correlations is discussed. The more general cases, which allow spin-orbital separation by the same method, are pointed out. A generalization for the orbital pseudospin greater than 1/2 is also discussed. Some qualitative connections are drawn with the recently observed spin-orbital separation in Sr2CuO3.Comment: 5 page

Quantum Disordered Ground States in Frustrated Antiferromagnets with Multiple Ring Exchange Interactions

We present a certain class of two-dimensional frustrated quantum Heisenberg spin systems with multiple ring exchange interactions which are rigorously demonstrated to have quantum disordered ground states without magnetic long-range order. The systems considered in this paper are s=1/2 antiferromagnets on a honeycomb and square lattices, and an s=1 antiferromagnet on a triangular lattice. We find that for a particular set of parameter values, the ground state is a short-range resonating valence bond state or a valence bond crystal state. It is shown that these systems are closely related to the quantum dimer model introduced by Rokhsar and Kivelson as an effective low-energy theory for valence bond states.Comment: 6 pages, 4 figure

One-pot synthesis of 5-amino-2,5-dihydro-1-benzoxepines: access to pharmacologically active heterocyclic scaffolds

A one-pot multibond-forming process involving a thermally mediated Overman rearrangement and a ring closing metathesis reaction of allylic trichloroacetimidates bearing a 2-allyloxyaryl group has been developed for the synthesis of 5-amino-substituted 2,5-dihydro-1-benzoxepines. Chemoselective reduction and functionalization of these compounds allowed access to a range of pharmacologically active 5-amino-2,3,4,5-tetrahydro-1-benzoxepine scaffolds

Dynamometer for measuring machining forces in two perpendicular directions

Published report discusses development of two-component force dynamometer which is used for dynamic measurement of machining forces in cutting and thrust directions. Resulting data suggest that faster metal-cutting machines may be developed that have reduced vibrations

Model of the Formation of Iron Oxide Nanoparticles by Irradiation in Aqueous Media

This thesis aims to develop the mechanistic understanding of the formation of iron oxide nanoparticles by γ-irradiation. Under irradiation water breaks down into a wide array of redox active species (H•, •OH, H2O2, •e-(aq)) uniformly throughout the solution. These species are capable of rapidly interconverting any soluble FeII and insoluble FeIII species resulting in the formation of nanoparticles with a narrow size distribution. The initial concentration of Fe2+ in the solution, the solution pH, the presence of any radical scavengers, the temperature of the reaction, and the dose rate of the Co60 source were all parameters investigated to elucidate this mechanism. UV-Vis spectrographic methods, gas chromatography, pH, and transmission electron microscopy were used to study the kinetics of the solution and growing particles. Raman, Fourier transform infrared spectroscopy, x-ray absorption near edge spectroscopy were employed to study the final composition of particles. Computer modelling was employed to model the water radiolysis speciation. It was found that the growth follows a three stage mechanism. The first stage involves the rapid oxidation of Fe2+ to FeIII by •OH which forms the initial nucleate sites. Lower initial pH values will favour larger particles because the FeIII species will be more soluble and fewer nucleates will form. Lower dose rates will also favour larger particles because fewer nucleates are generated initially. In the second stage, H2O2 is responsible for the bulk oxidation of Fe2+ which adsorbs on the surface of these initial nucleates. The nucleates convert to mixed oxide FeOOH intermediates. The second stage ends when the reverse reduction reactions are capable of competing with the forward oxidation reactions. Solutions with higher initial Fe2+ concentrations stay in the growth stage for longer periods of time resulting in larger particles. The final stage is the pseudo steady-state in which continuous cycling of FeII and FeIII species by H2O2 converts the oxide to magnetite with residual mixed oxides incorporated in the system. The system continues to undergo radiation-assisted Ostwald ripening. Temperature promotes this ripening by rapidly converting the residual mixed oxides in the system allowing the particles to agglomerate

Subduction Duration and Slab Dip

The dip angles of slabs are among the clearest characteristics of subduction zones, but the factors that control them remain obscure. Here, slab dip angles and subduction parameters, including subduction duration, the nature of the overriding plate, slab age, and convergence rate, are determined for 153 transects along subduction zones for the present day. We present a comprehensive tabulation of subduction duration based on isotopic ages of arc initiation and stratigraphic, structural, plate tectonic and seismic indicators of subduction initiation. We present two ages for subduction zones, a long‐term age and a reinitiation age. Using cross correlation and multivariate regression, we find that (1) subduction duration is the primary parameter controlling slab dips with slabs tending to have shallower dips at subduction zones that have been in existence longer; (2) the long‐term age of subduction duration better explains variation of shallow dip than reinitiation age; (3) overriding plate nature could influence shallow dip angle, where slabs below continents tend to have shallower dips; (4) slab age contributes to slab dip, with younger slabs having steeper shallow dips; and (5) the relations between slab dip and subduction parameters are depth dependent, where the ability of subduction duration and overriding plate nature to explain observed variation decreases with depth. The analysis emphasizes the importance of subduction history and the long‐term regional state of a subduction zone in determining slab dip and is consistent with mechanical models of subduction