Suspended bed chromatography, a new approach in downstream processing

A new technique in downstream processing, suspended bed chromatography has been developed. This hybrid technique exploiting the benefits of batch adsorption and the process advantages of an enclosed column system can be carried out using established contactors and adsorbents. A 44 cm I.D. IsoPak column and the anion-exchange cellulose Express-Ion Exchanger Q were used in the purification of ovalbumin from hen-egg white. After suspension of 16.25 kg Express-Ion Q in 500 l of feedstock containing 5 g protein/l, adsorption was effected by recirculation of the suspension using the IsoPak slurry preparation station. Protein-loaded adsorbent was collected in the IsoPak column unit, where it was washed and protein desorbed using gradient elution at a flow-rate of 300 cm/h. The entire process was complete in under 3 h. With the introduction of pump-packed column systems and the availability of mechanically strong adsorbents suitable for column separations, suspended bed chromatography offers a new approach to downstream processing and provides a less challenging alternative to batch separations.     

Influence of mobile phase composition on the adsorption of hen egg-white proteins to anion-exchange cellulose

Summary Factors influencing the capacity of Whatman QA52 anion-exchange cellulose for hen egg-white proteins have been investigated. While simply increasing the concentration of protein in the feedstock increases the loading there is a concomitant reduction in binding efficiency in a single pass through the column. Substitution of buffer by water in the mobile phase during sample preparation, thereby reducing the ionic strength of the feedstock, had the effect of significantly increasing protein capacity whilst improving binding efficiency. During column loading large changes in pH of the mobile phase were observed although this had no apparent effect on the chromatography for this system.     

Effect of three-body forces on the lattice dynamics of noble metals

A simple method to generate an effective electron-ion interaction pseudopotential from the energy wave number characteristic obtained by first principles calculations has been suggested. This effective potential has been used, in third order perturbation, to study the effect of three-body forces on the lattice dynamics of noble metals. It is found that three-body forces, in these metals, do play an important role. The inclusion of such three-body forces appreciably improves the agreement between the experimental and theoretical phonon dispersion curves.     

An ultra-low hydrolysis sol-gel route for titanosilicate xerogels and their characterization

In this work TiO₂-SiO₂ xerogels were prepared through an ultra low hydrolysis method using titanium and silicon alkoxide. The samples were heat treated to 500°C. The xerogels were characterized using TGA/DTA, FTIR, XRD and TEM. The samples showed the formation of Si–O–Ti bridges by its characteristic vibration within 925–960 cm⁻¹ range. Si–O–Si bond angles were calculated using the central force network model. The TiO₂ in all the samples crystallized on heat treatment to 500°C. The crystallite size calculated using the Scherer formula from the XRD was verified from the Transmission Electron Micrograph. Samples heat treated to 350°C remained amorphous and hence could be used as hosts for biomaterials and organic optical materials.     

A new coumarin from Wikstroemia indica （L.） C. A. Mey

A new coumadn was obtained from the stems and roots of Wikstroemia indica (L.) C.A.Mey.Its structure was elucidated as methyl 3-(2-hydroxy-4-(7-hydroxy-6-methoxy-2-oxo-2H-chromen-3-yloxy) phenyl) propanoate by spectroscopic methods.     

Gallium trichloride-catalyzed conjugate addition of indole and pyrrole to α,β-unsaturated ketones in aqueous media

Michael addition of indole and pyrrole to a variety ofα,β-unsaturated ketones was efficiently promoted by a catalytic amount of GaCl_3 in aqueous media to afford the corresponding products in good to excellent yields.     

Synthesis and biological evaluation of novel steroid-linked nitrogen mustards

Two novel steroid-linked nitrogen mustard conjugates 1a and 1b were synthesized by using estrogenic acid 4 coupled with aniline mustard 8 and phenol mustard 13 in an esterification or amidation procedure. Preliminary cytotoxic screening on cancer cell lines in vitro showed that, the steroid-ester linked nitrogen mustard conjugate la exhibited obvious increasing of activities.     

Oxyphyllones A and B,novel sesquiterpenes with an unusual 4,5-secoeudesmane skeleton from Alpinia oxyphylla

Two novel 4,5-secoeudesmane sesquiterpenoids,oxyphyllones A(1) and B(2) were isolated from the fruits of Alpinia oxyphylla.Their structures were established by spectroscopic methods including 1D and 2D NMR spectra.These two compounds are the first example of naturally occurring sesquiterpenoids with a 4,5-secoeudesmane skeleton in the family of Zingiberaceae and oxyphyllone A(1) is the first 4,5-secoeudesmane type of 13-norsesquiterpenoid.Compounds 1 and 2 exhibited no cytotoxicities against three cancer...     

Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry

The inclusion interaction between berberine hydrochloride(BRH) and cucurbit[7](CB[7]) has been studied by spectro-fluorimetry. The result showed that CB[7]interaction with BRH to form a stable inclusion complex with an association constant of 9.57×10~4 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of B RH in inclusion complex,a spetrofluorimetric method with high sens...     

Inclusion of 3d orbitals in calculations involving second row atoms

Valence-state ionisation potentials, I , and non-empirical one-centre electron repulsion integrals are evaluated for the separate 3s, 3p and 3d orbitals of Na, Mg, Al, Si, P, S, and Cl. These parameters are for use in the application of the CNDO SCMO method to molecules containing second row atoms.

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Zusammenfassung Die Ionisierungspotentiale des Valenzzustands, I und die nicht-empirischen Ein-Zentren-Elektronen-Absto\ungsintegrale werden für die 3s-, 3p- und 3d-Orbitale von Na, Mg, Al, Si, P, S und Cl angegeben. Diese Parameter werden bei der Anwendung der CNDO-SCMO-Methode auf Moleküle, die Atome der zweiten Reihe enthalten, benötigt.

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Résumé On détermine les potentiels d'ionisation de l'état de valence I et les intégrales de répulsion monocentriques pour les orbitales 3s, 3p, 3d de Na, Mg, Al, Si, P, S et Cl. Ces paramètres sont utilisés dans l'application de la méthode CNDO SCMO à des molécules contenant des atomes de la seconde colonne.

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We thank the S.R.C. for a maintenance grant (to K.A.L.).