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Affinity ultrafiltration for protein purification

Purification of a biochemical product from fermentation broths or other complex biological mixtures generally involves a combination of techniques which resolve substances according to differences in their physicochemical properties. These techniques have traditionally been optimized individually rather than as a part of the integrated, continuous process. Moreover, a lot of the development and re

Single-step partitioning in aqueous two-phase systems

Partitioning in aqueous two-phase system (ATPS) provides a rapid and gentle means of separation of soluble as well as particulate biomaterials, e.g. proteins, nucleic acids, cells, viruses, organelles, and membranes. Partitioning between the two phases is a complex phenomenon, guided mainly by the interaction of the partitioned substance and the phase components, e.g., through hydrogen bonds, van

Integration of extraction with affinity precipitation

Conventional aqueous two-phase extraction by spontaneous partitioning has often problems with low specificity. The introduction of an affinity ligand into one of the phases has been attempted to enhance the specificity of protein partitioning (1-7; Chapters 29-31). However, this procedure still has some limitations in the effective removal of impurities as well as recovery and reuse of the ligand.

Structure and high photocatalytic activity of (N, Ta)-doped TiO2 nanoparticles

A hydrothermal method was used to prepare three nano-crystalline samples of TiO2 (S1), N-doped TiO2 (S2), and (N, Ta)-codoped TiO2 (S3) with average crystallite sizes (D) of 13-25 nm. X-ray diffraction studies confirmed a single phase of the samples with a tetragonal/anatase structure. A slight increase in the lattice parameters was observed when N and/or Ta dopants were doped into the TiO2 host l

Energy dispersive-EXAFS of Pd nucleation at a liquid/liquid interface

Energy dispersive extended X-ray absorption fine structure (EDE) has been applied to Pd nanoparticle nucleation at a liquid/liquid interface under control over the interfacial potential and thereby the driving force for nucleation. Preliminary analysis focusing on Pd K edge-step height determination shows that under supersaturated conditions the concentration of Pd near the interface fluctuate ove

Detection and characterisation of sub-critical nuclei during reactive Pd metal nucleation by X-ray absorption spectroscopy

The interfacial reduction of aqueous [PdCl4]2- at the interface with an organic solution of ferrocene has been characterised by X-ray absorption fine structure (XAFS) spectroscopy. Use of a liquid-liquid interface as a model for homogeneous nucleation permits control of the thermodynamic driving force for nucleation, through variation of the [PdCl4]2- and ferrocene concentrations in the bulk of th

High-resolution Measurement of Contact Ion-pair Structures in Aqueous RbCl Solutions from the Simultaneous Corefinement of their Rb and Cl K-edge XAFS and XRD Spectra

In concentrated solutions of aqueous RbCl, all of the Rb+ and Cl– ions exist as contact ion pairs. This full structural assessment is derived from the refinement of three independent experimental measurements: the Rb and Cl K-edge X-ray absorption fine structure (XAFS) and the X-ray diffraction spectra (XRD). This simultaneous refinement of the XAFS and XRD data provides high accuracy since each m

The structure of liquid water up to 360 MPa from x-ray diffraction measurements using a high Q-range and from molecular simulation

X-ray diffraction measurements of liquid water are reported at pressures up to 360 MPa corresponding to a density of 0.0373 molecules per Å3. The measurements were conducted at a spatial resolution corresponding to Qmax = 16 Å-1. The method of data analysis and measurement in this study follows the earlier benchmark results reported for water under ambient conditions having a density of 0.0333 mol

The aerobic oxidation of bromide to dibromine catalyzed by homogeneous oxidation catalysts and initiated by nitrate in acetic acid

For ∼50 years mixtures of cobalt(II) and manganese(II) acetates with sodium bromide or hydrobromic acid in acetic acid have been used as catalysts for the homogeneous aerobic oxidation of alkylaromatic compounds. They are known to be stable mixtures. While characterizing this mixture via EXAFS, it was thus surprising to observe an unexpected change in the color of the reaction mixture from deep bl

State of supported Pd during catalysis in water

The structure and chemical state of supported Pd nanoparticles in contact with H 2 in the aqueous phase have been explored by X-ray absorption spectroscopy to better understand their surface reactivity in polar condensed media. The Pd-Pd distances at substantial H 2 pressures indicate the presence of sorbed hydrogen and point to the presence of Pd hydrides, proving that such nanoparticles are har

Ion-pairing in aqueous CaCl2 and RbBr solutions : Simultaneous structural refinement of XAFS and XRD data

We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (x-ray absorption/diffraction structural refinement, XADSR) to study the hydration and ion pair structure of CaCl2 and RbBr salts in concentrated aqueous solutions. The XADSR method combines the x-ray absorption fine structure (XAFS) spectral analysis of both the cation and ani

X-ray absorption spectroscopy of ground and excited rhenium-carbonyl- diimine complexes : Evidence for a two-center electron transfer

Steady-state and picosecond time-resolved X-ray absorption spectroscopy is used to study the ground and lowest triplet states of [ReX(CO) 3 (bpy)] n+ , X = Etpy (n = 1), Cl, or Br (n = 0). We demonstrate that the transient spectra at both the Re L 3 -and Br K-edges show the emergence of a pre-edge feature, absent in the ground-state spectrum, which is associated with the electron hole created in

A variable ultra-short-pathlength solution cell for XAFS transmission spectroscopy of light elements

An X-ray absorption fine-structure spectroscopy (XAFS) cell that is suitable for solution-phase studies of the light elements in the series from Na+ and Ca2+ is described. This cell has an ultra-short pathlength that can be remotely adjusted using a miniature stepper-motor drive and thereby readily provides transmission pathlengths in the range from submicrometer to several hundred micrometers. Th

Is iodate a strongly hydrated cation?

We show, through a combination of density function theory-based molecular dynamics simulations (DFT-MD) and experimental X-ray absorption fine structure spectroscopy (XAFS) studies, that the iodate ion (IO 3 -) contains a local region that is strongly hydrated as a cation. The local region adjoining the I atom is sufficiently electropositive that three hydrating waters are oriented with their O at

Probing the transition from hydrophilic to hydrophobic solvation with atomic scale resolution

Picosecond and femtosecond X-ray absorption spectroscopy is used to probe the changes of the solvent shell structure upon electron abstraction of aqueous iodide using an ultrashort laser pulse. The transient L 1,3 edge EXAFS at 50 ps time delay points to the formation of an expanded water cavity around the iodine atom, in good agreement with classical and quantum mechanical/molecular mechanics (

Compliance with the Very Integrated Program (VIP) for Smoking Cessation, Nutrition, Physical Activity and Comorbidity Education Among Patients in Treatment for Alcohol and Drug Addiction

Meeting adherence is an important element of compliance in treatment programmes. It is influenced by several factors one being self-efficacy. We aimed to investigate the association between self-efficacy and meeting adherence and other factors of importance for adherence among patients with alcohol and drug addiction who were undergoing an intensive lifestyle intervention. The intervention consistMeeting adherence is an important element of compliance in treatment programmes. It is influenced by several factors one being self-efficacy. We aimed to investigate the association between self-efficacy and meeting adherence and other factors of importance for adherence among patients with alcohol and drug addiction who were undergoing an intensive lifestyle intervention. The intervention consist