TS-1 zeolite microengineered reactors for 1-pentene epoxidation

A zeolite-based microengineered reactor was fabricated and tested for 1-pentene epoxidation over titanium silicalite-1 (TS-1) catalyst, which has been selectively incorporated within the microreactor channel using a new synthesis procedure.     

Parallel screening of homogeneous copper catalysts for the oxidation of benzylic alcohols with molecular oxygen in aqueous solutions

A simple and efficient parallel screening method to evaluate the catalytic activities of homogeneous copper complexes for the oxidation of benzylic alcohols in aqueous solutions with molecular oxygen is reported. Copper(II) sulfate was treated in situ with 22 nitrogen donor ligands, and the catalytic activities of these combinations were studied at four different pH values with two substrates (benzyl alcohol and 3,4-dimethoxy benzyl alcohol (veratryl alcohol)), resulting in 176 oxidation experiments in the primary screening stage. Copper complexes based on N,N,N',N'-tetramethyl ethylenediamine (TMEDA), 9,10-diaminephenanthrene (DAPHEN), and 1,2-diaminocyclohexane (DACH) were determined to be the most active catalysts. In the second screenings, the influence of reaction conditions on Cu(DACH)-, Cu(TMEDA)-, and Cu(DAPHEN)-catalyzed reactions were investigated in more detail. It was found that highly basic reaction conditions favor the reaction with the exception of Cu(TMEDA), which is active at a lower pH range. Under optimized conditions, Cu(DAPHEN) catalyzes the transformation of veratryl alcohol to the corresponding aldehyde with 100% conversion.     

The effect of a low-frequency sound source (acoustic thermometry of the ocean climate) on the diving behavior of juvenile northern elephant seals,Mirounga angustirostris

Changes in the diving behavior of individual free-ranging juvenile northern elephant seals, Mirounga angustirostris, exposed to the acoustic thermometry of the ocean climate (ATOC) sound source were examined using data loggers. Data loggers were attached to the animals and measured swim speed, maximum depth of dive, dive duration, surface interval, descent and ascent rate, and descent and ascent angle along with sound pressure level (SPL). The ATOC sound source was at a depth of 939 m and transmitted at 195 dB re: 1 microPa at 1 m centered at 75 Hz with a 37.5-Hz bandwidth. Sound pressure levels (SPL) measured at the seal during transmissions averaged 128 dB and ranged from 118 to 137 dB re: 1 microPa for the 60-90 Hz band, in comparison to ambient levels of 87-107 dB within this band. In no case did an animal end its dive or show any other obvious change in behavior upon exposure to the ATOC sound. Subtle changes in diving behavior were detected, however. During exposure, deviations in descent rate were greater than 1 s.d. of the control mean in 9 of 14 seals. Dive depth increased and descent velocity increased in three animals, ascent velocity decreased in two animals, ascent rate increased in one animal and decreased in another, and dive duration decreased in only one animal. There was a highly significant positive correlation between SPL and descent rate. The biological significance of these subtle changes is likely to be minimal. This is the first study to quantify behavioral responses of an animal underwater with simultaneous measurements of SPL of anthropogenic sounds recorded at the animal.     

RNA cleavage and inhibition of protein synthesis by bleomycin

Bleomycin is a clinically used antitumor antibiotic long thought to function therapeutically at the level of DNA cleavage. Recently, it has become clear that bleomycin can also cleave selected members of all major classes of RNA. Using the computer program COMPARE to search the database established by the Anticancer Drug Screening Program of the National Cancer Institute, a possible mechanism-based correlation was found between onconase, an antitumor ribonuclease currently being evaluated in phase III clinical trials, and the chemotherapeutic agent bleomycin. Following these observations, experimentation revealed that bleomycin caused tRNA cleavage and DNA-independent protein synthesis inhibition in rabbit reticulocyte lysate and when microinjected into Xenopus oocytes. The correlation of protein synthesis inhibition to the previously reported site-specific RNA cleavage caused by bleomycin supports the thesis that RNA cleavage may constitute an important element of the mechanism of action of bleomycin.     

Adsorptive refolding of a highly disulfide-bonded inclusion body protein using anion-exchange chromatography

α-Fetoprotein (AFP) is a prospective biopharmaceutical candidate currently undergoing advanced-stage clinical trials for autoimmune indications. The high AFP expression yields in the form of inclusion bodies in Escherichia coli renders the inclusion body route potentially advantageous for process scale commercial manufacture, if high-throughput refolding can be achieved. This study reports the successful development of an ‘anion-exchange chromatography’-based refolding process for recombinant human AFP (rhAFP), which carries the challenges of contaminant spectrum and molecule complexity. rhAFP was readily refolded on-column at rhAFP concentrations unachievable with dilution refolding due to viscosity and solubility constraints. DEAE-FF functioned as a refolding enhancer to achieve rhAFP refolding yield of 28% and product purity of 95% in 3 h, at 1 mg/ml protein refolding concentration. Optimization of both refolding and chromatography column operation parameters (i.e. resin chemistry, column geometry, redox potential and feed conditioning) significantly improved rhAFP refolding efficiency. Compared to dilution refolding, on-column rhAFP refolding productivity was 9-fold higher, while that of off-column refolding was more than an order of magnitude higher. Successful demonstration that a simple anion-exchange column can, in a single step, readily refold and purify semi-crude rhAFP comprising 16 disulfide bonds, will certainly extend the application of column refolding to a myriad of complex industrial inclusion body proteins.     

High molar mass ethene/1‐olefin copolymers synthesized with acenaphthyl substituted metallocene catalysts

The influence of ligand structure on copolymerization properties of metallocene catalysts was elucidated with three C₁‐symmetric methylalumoxane (MAO) activated zirconocene dichlorides, ethylene(1‐(7, 9)‐diphenylcyclopenta‐[a]‐acenaphthadienyl‐2‐phenyl‐2‐cyclopentadienyl)ZrCl₂ ( 1 ), ethylene(1‐(7, 9)‐diphenylcyclopenta‐[a]‐acenaphthadienyl‐2‐phenyl‐2‐fluorenyl)ZrCl₂ ( 2 ), and ethylene(1‐(9)‐fluorenyl‐(R)1‐phenyl‐2‐(1‐indenyl)ZrCl2 ( 3 ). Polyethenes produced with 1 /MAO had considerable, ca. 10% amount of trans‐vinylene end groups, resulting from the chain end isomerization prior to the chain termination. When ethene was copolymerized with 1‐hexene or 1‐hexadecene using 1 /MAO, molar mass of the copolymers varied from high to moderate (531–116 kg/mol) depending on the comonomer feed. At 50% comonomer feed, ethene/1‐olefin copolymers with high hexene or hexadecene content (around 10%) were achievable. In the series of catalysts, polyethenes with highest molar mass, up to 985 kg/mol, were obtained with sterically most crowded 2 /MAO, but the catalyst was only moderately active to copolymerize higher olefins. Catalyst 3 /MAO produced polyethenes with extremely small amounts of trans‐vinylene end groups and relatively low molar mass 1‐hexene copolymers (from 157 to 38 kg/mol) with similar comonomer content as 1 . These results indicate that the catalyst structure, which favors chain end isomerization, is also capable to produce high molar mass 1‐olefin copolymers with high comonomer content. In addition, an exceptionally strong synergetic effect of the comonomer on the polymerization activity was observed with catalyst 3 /MAO. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 373–382, 2008