Modelling methyl tertiary butyl ether and tertiary butyl alcohol biodegradation by a bacterial consortium

The widespread use of methyl tertiary butyl ether (MTBE) as an additive in gasoline has resulted in serious soil and groundwater pollution. To tackle MTBE contamination in groundwater, bioremediation is considered a cost-effective and energy-efficient option. The design of an efficient, reliable and reproducible bioremediation strategy requires a thorough understanding of the (microbial) degradation kinetics of both MTBE and tertiary butyl alcohol (TBA), that is, the main intermediate during bioremediation of MTBE. To assist the design procedure, this research focuses on building a mathematical model to describe MTBE/TBA degradation kinetics by a bacterial consortium, that is, the VITO M-consortium.

For the presented case study, the information obtained from experimental data is combined with knowledge regarding the biodegradation reactions in order to obtain a low-complexity, accurate mathematical model. The resulting model accurately describes MTBE/TBA degradation and has successfully been validated on independent experimental data. Since the model is of the mass balance type, it can easily be extended to other types of operation by defining the transport terms of the new system. This makes the model a very useful tool in the design procedure for large-scale bioremediation strategies. Furthermore, the model provides insight into the MTBE/TBA degradation kinetics and biodegradation mechanisms by hypothesis testing.     

Synthesis of water-soluble scaffolds for peptide cyclization, labeling, and ligation

The synthesis and applications of water-soluble scaffolds that conformationally constrain side chain unprotected linear peptides containing two cysteines are described. These scaffolds contain a functionality with orthogonal reactivity to be used for labeling and ligation. This is illustrated by the chemical ligation of two dissimilar constrained peptides via oxime ligation or strain-promoted azide-alkyne cycloaddition in aqueous media.     

Characteristics of the loss modulation of intracavity Raman-Nath acousto-optic devices

Acousto-optic loss modulators for applications in active mode-locking of lasers are discussed. We show that intracavity interference effects can either enhance or decrease the modulation efficiency. Optical, electrical, and acoustic measurements for the characterization of mode-locking devices are described.     

The annular space between rotating cylinders as a geometry for open-channel liquid chromatography

Summary The annular slit between two cylinders, one of which is rotating, looks attractive for carrying out open channel LC, with chromatographic flow in the axial direction. Under ideal conditions, the dynamics of chromatographic separation are as good as those prevailing in an open tubular column.As is the case for Myers and Gidding's open parallelplate LC, the sample capacity of the proposed geometry can be much higher than of open tubular chromatography.Rotation of one of the cyclinders offers two advantages, which may be helpful in achieving the ideal situation. First, the thickness of the slit between the cylinders tends to be more uniform at higher rotation speeds. Second, the increased mixing of the liquid in the direction perpendicular to chromatographic flow can be expected to diminish the detrimental effect of any remaining lack of uniformity in the thickness of the slit and the capacity factors.Preliminary results with such a system are reported.Dedicated to Professor J. F. K. Huber on the occasion of his 60th birthday.     

The mode structure and spectral properties of supercontinuum emission from microstructure fibers

The mode structure and spectral properties of supercontinuum emission generated by femtosecond pulses of Ti: sapphire laser radiation in microstructure fibers are studied. The long-wavelength (720–900 nm) and visible (400–600 nm) parts of supercontinuum emission are shown to be spatially separated in microstructure-fiber modes, which can be isolated with an appropriate spectral filtering. The spatial modes thus isolated in spectrally sliced supercontinuum emission possess a spatial quality sufficient for further efficient frequency conversion. The possibility of achieving a high spectral quality of supercontinuum emission is also demonstrated. We explore the ways to control the spectrum of supercontinuum emission by matching parameters of the pump pulse with the parameters of a microstructure fiber and by tuning the initial chirp of the pump pulse. The results of our studies show that supercontinua produced in microstructure fibers offer new approaches to designing a new generation of optical parametric amplifiers and broadband radiation sources for spectroscopic, metrological, and biomedical applications.