Reactive extraction of diols with phenyl boronic acid and trioctylmethylammonium chloride as coextractants and quantitative structure–property relationship of their extraction behaviors

BACKGROUND: Diols that can be produced biologically have attracted much attention because of the increased cost of producing them chemically. The cost of separating the diols from the broth forms a major part of the total cost of microbial production. Reactive extraction using organoboronate is one promising method for recovering diols from the dilute aqueous solution. RESULTS: A basic investigation of solvent extraction of diols was conducted at 303 K employing phenylboronic acid and trioctylmethylammonium chloride as coextractants in the mixed solvent. Both the tetrahedral boronate anion complex and trigonal boronate neutral complex were extracted. 1,3‐diols and vicinal diols were extracted, but 1,4‐diol was not extracted. Extraction equilibrium constants were correlated with the enthalpies of formation of the complexes, which were calculated by molecular modeling with semi‐empirical molecular orbital calculations considering the solvent effect. CONCLUSION: The complex extraction behaviour of diols with phenylboronic acid and quaternary ammonium salt can be predicted by using the quantitative structure–property relationship (QSPR). Copyright © 2009 Society of Chemical Industry     

SeamlessDesign for 3D object creation

The paper discusses SeamlessDesign, a novel collaborative workspace for rapid creation of 3D objects with constraints. Its seamless design supports both shape and behavioral designs of 3D objects in a unified and intuitive manner. Virtual and augmented setups support both multiple perspectives for parallel activity and face-to-face interaction for rich awareness     

Characteristics of surface roughening during plane strain compression of polycrystalline iron

Roughening behavior of the free surface of polycrystalline iron during plane strain compression is investigated experimentally. The changes in the shape of the free surface, which is roughened during plastic deformation, are observed in the three-dimensions. It is found that the mountains and the valleys of the roughened shape tend to elongate in the constrained direction for the specimen with isotropic grain shape. The shapes of the roughness curves in the loading direction and in the constrained direction are compared. The normalized height distribution of the roughness curve in the constrained direction is symmetric, while that of the roughness curve in the loading direction is asymmetric and positively skew during plane strain compression. Based on a simple simulation of the roughness curves by a random midpoint displacement method, this difference is supposed to be caused by the constraint of the material flow under plane strain condition.     

Liposome‐Based in Vitro Evolution of Aminoacyl‐tRNA Synthetase for Enhanced Pyrrolysine Derivative Incorporation

Methanosarcina species pyrrolysyl‐tRNA synthetase (PylRS) attaches Pyl to its cognate amber suppressor tRNA. The introduction of two mutations (Y384F and Y306A) into PylRS was previously shown to generate a mutant, designated LysZ‐RS, that was able to attach N‐benzyloxycarbonyl‐L ‐lysine (LysZ) to its cognate tRNA. Despite the potential of LysZ derivatives, further LysZ‐RS engineering has not been performed; consequently, we aimed to generate LysZ‐RS mutants with improved LysZ incorporation activity through in vitro directed evolution. Using a liposome‐based in vitro compartmentalization (IVC) approach, we screened a randomly mutagenized gene library of LysZ‐RS and obtained a mutant that showed increased LysZ incorporation activity both in vitro and in vivo. The ease and high flexibility of liposome‐based IVC should enable the evolution of not only LysZ‐RS that can attach various LysZ derivatives but also of other enzymes involved in protein translation.     

Supramolecular Ligands for Histone Tails by Employing a Multivalent Display of Trisulfonated Calix[4]arenes

Post‐translational modification of histone tails plays critical roles in gene regulation. Thus, molecules recognizing histone tails and controlling their epigenetic modification are desirable as biochemical tools to elucidate regulatory mechanisms. There are, however, only a few synthetic ligands that bind to histone tails with substantial affinity. We report CA2 and CA3, which exhibited sub‐micromolar affinity to histone tails (especially tails with a trimethylated lysine). Multivalent display of trisulfonated calix[4]arene was important for strong binding. CA2 was applicable not only to synthetic tail peptides but also to endogenous histone proteins, and was successfully used to pull‐down endogenous histones from nuclear extract. These findings indicate the utility of these supramolecular ligands as biochemical tools for studying chromatin regulator protein and as a targeting motif in ligand‐directed catalysis to control epigenetic modifications.     

Purification, characterization, and steady-state kinetics of a meta-cleavage compound hydrolase from Pseudomonas fluorescens IPO1

2-Hydroxy-6-oxo-7-methylocta-2,4-dienoate (6-isopropyl-HODA) hydrolase (CumD), an enzyme of the cumene biodegradation pathway encoded by the cumD gene of Pseudomonas fluorescens IP01, was purified to homogeneity from an overexpressing Escherichia coli strain. SDS-polyacrylamide gel electrophoresis and gel filtration demonstrated that it is a dimeric enzyme with a subunit molecular mass of 32 kDa. The pH optima for activity and stability were 8.0 and 7.0-9.0, respectively. The enzyme exhibited a biphasic Arrhenius plot of catalysis with two characteristic energies of activation with a break point at 20 degrees C. The enzyme has a K(m) of 7.3 microM and a k(cat) of 21 s(-1) for 6-isopropyl-HODA (150 mM phosphate, pH 7.5, 25 degrees C), and its substrate specificity covers larger C6 substituents compared with another monoalkylbenzene hydrolase, TodR Unlike TodF, CumD could slightly hydrolyze 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate (6-phenyl-HODA). A mutant enzyme as to a putative active site residue, S103A, had 10(5)-fold lower activity than that of the wild-type enzyme.     

Field instrument for simultaneous large dynamic range measurement of atmospheric hydrogen sulfide, methanethiol, and sulfur dioxide

We describe a membrane-based collection/analysis system that differentially monitors H2S and CH3SH, and to which a conductometric SO2 analyzer using the same collector was coupled. A diffusion scrubber (DS) comprised of a Nafion tube collects H2S selectively while a porous polytetrafluoroethylene (pPTFE) DS collects both H2S and CH3SH. Both gases are measured via their ability to react with fluorescein mercuric acetate (FMA) which results in decreased fluorescence. The limited dynamic range of a negative signal procedure was overcome by using dual DS units comprised of short and long scrubbers, placed serially in the liquid flow line. Different DS designs and membrane materials were investigated. H2S, CH3SH, and SO2 from a biogenic point source were continuously measured, and the H2S/CH3SH data compared well with a standard procedure involving Tedlar bag collection, preconcentration and thermal desorption from a Tenax trap, and measurement by gas chromatography/flame photometric detection. Walkaround portability of the instrument and very large dynamic range measurement of H2S and SO2 were demonstrated around the Mt. Aso volcano.     

ADSORPTION BEHAVIOR OF COBALT( II) IONS ON LAYERED DIHYDROGEN TETRATITANATE HYDRATE FIBERS IN AQUEOUS SOLUTIONS IN THE RANGE FROM 298 to 523 K

The adsorption properties of cobalt(II) ions have been studied on layered dihydrogen tetratitanate hydrate fibers, H₂Ti₄O₉,?nH₂O, in the temperature range from 298 to 523?K. The distribution coefficients of the adsorption of cobalt (II) ions were increased with increasing temperatures up to 367?K, but were decreased in the temperature range between 367 and 523?K. The X-ray powder diffraction patterns of the fibers indicate that the fibers hold layer structure up to 367?K, but change to low crystalline anatase or its precursor above that temperature. It is notable that the material has the capability of cobalt (II) adsorption even at 523?K, although the maximum is present at 367?K.     

ION-EXCHANGE PROPERTIES OF HYDROUS TITANIUM DIOXIDE WITH A FIBROUS FORM OBTAINED FROM POTASSIUM DITITANATE

ABSTRACT

Ion-exchange properties of a new type of hydrous titanium dioxide with a fibrous form, which was obtained from potassium dititanate (K₂O(TiO₂)2), have been studied. The pH titration curve snowed that this material behaved as a bifunctional ion-exchanger. Distribution coefficients of some divalent metal ions on this material were measured as a function of pH and the selectivity series were found to be Ba > Sr > Ca > Mg for alkaline earth metal ions and Cu > Zn > Mn > Co > Ni for divalent transition metal ions. Large separation factors were obtained between some metal ion pairs and the mutual separations such as Cu from Sr, Ca, Mg, Co and Ni, and Mg from Ba and Zn have been achieved on columns of this material.     

Input-output linearization of retarded non-linear systems by using an extension of Lie derivative

This paper considers the input-output linearization problem for retarded non-linear systems, which have time-delays in the state. By using an extension of the Lie derivative for functional differential equations, we derive a coordinates transformation and a static state feedback to obtain linear input-output behaviour for a class of retarded non-linear systems. The obtained coordinates transformation is allowed to contain not only the current value of the state variables but also the past values of ones. In addition, we show that the coordinates transformation is invertible in a neighbourhood of the origin and examine the stability condition of the closed loop system with the static state feedback. The effectiveness of the proposed technique is demonstrated through numerical simulations.