Active‐Site Engineering Expands the Substrate Profile of the Basidiomycete l‐Tryptophan Decarboxylase CsTDC

Aromatic l ‐amino acid decarboxylases (AADCs) catalyze the release of CO₂ from proteinogenic and non‐proteinogenic l ‐amino acid substrates and are involved in pathways that biosynthesize neurotransmitters or bioactive natural products. In contrast to AADCs from animals and plants, fungal AADCs have received very little attention. Here, we report on the in vitro characterization of heterologously produced Ceriporiopsis subvermispora AADC, now referred to as CsTDC, which is the first characterized basidiomycete AADC. This study identified the enzyme as a decarboxylase that is strictly specific for l ‐tryptophan and 5‐hydroxy‐l ‐tryptophan. The tdc gene was subjected to saturation mutagenesis so as to vary the key active site residue, Gly351. Aliphatic amino acid residues, l ‐serine, or l ‐threonine at position 351 added l ‐tyrosine and 3,4‐dihydroxy‐l ‐phenylalanine (l ‐DOPA) decarboxylase activity while retaining stereospecificity and l ‐tryptophan decarboxylase activity.     

Pharmacology of Bay g 2821, a long-acting, high-ceiling diuretic

Bay g 2821 is a diuretic, from a new class of chemical substances, with both the efficacy of diuretics with a high-ceiling activity, such as furosemide, bumetanide and ethacrynic acid, and the prolonged duration of action of thiazides. Pharmacological investigations showed that Bay g 2821 was more potent than furosemide in dogs but less potent in rats. Bay g 2821 did not differ from furosemide in excretion of electrolytes. Further studies showed that Bay g 2821 had an antihypertensive effect in dogs, spontaneously hpertensive rats, and in rats with artificially-induced renal hypertension. Other pharmacological studies did not reveal any other significant effects.     

Quantitative Risikoanalysen in der chemischen Industrie

Quantitative risk analysis in the chemical industry . Consideration of risks on a qualitative basis is a useful, generally applied tool in safety engineering. However, attempts to quantify risk create problems. Quantifying studies have been published concrning nuclear and chemical plant, storage tanks, and port and transport facilities. At present, attempts are also being made in Germany to demonstrate that quantitative risk analysis is also possible for chemical processes. Instead of relying on past empirical values, an ab initio determination of risk from model calculations is being tried. A theoretical basis is already available for such calculations. However, practical execution and simplification of the complicated methods leads to numerous problems which are discussed in this paper. With the aid of selected examples attention is focussed on the following problems: (1) consideration of maintenance; (2) quality of starting data; (3) predictive power of weak-point analysis.     

Ultrasonic characterization of the curing process of PCC fly ash–cement composites

The effects of the type of fly ash, mix proportion, and curing process on the pozzolanic reaction of fly ash–cement paste were investigated by ultrasonic techniques. Specifically, the speed of sound (SOS) and broadband ultrasonic attenuation (BUA) were used to investigate hydration activities of the fly ash–cement composite. SOS provided direct evidence of the delay in the hydration activity caused by mixing fly ash to the cement. The rapid heat of evolution during hydration activity, as indicated by a rapid increase in SOS, resulted in early stiffening of the Class C fly ash–cement composite. However, Class C fly ash–cement composite achieved a lower elastic modulus compared with Class F fly ash–cement composite. The hydration activity is observed to be highly dependent on the type of fly ash substituted for cement in the composite. The BUA provided the indirect evidence of ionic activities occurring during the hydration period and viscoelastic properties of the material.     

Subjective Qualitative Information Structures Based on Orderings

Abstract

This paper is motivated by the following question: Can one axiomatize information first and then probability in terms of information rather than vice versa as suggested by information theory.

The emphasis here is on a new methodological approach toward a conceptualization of behavioral information which might be better suited for inferences involving nonrepeatable events or an sufficient number of repeatable events, based on the assumption that information is prior to probability statements.

The main idea is to generate (via a Boolean homomorphism) a Boolean algebra of events by an appropriate information structure and to utilize the notion of a topogeneous order similar to that of a Boolean order.     

Process-integrated quality assurance in wood machining centers with the help of image processing

With rising feed rates of wood working machines, it is important to realize a process-integrated quality assurance. The quality control of produced workpieces is mainly carried out by the operator. As his capabilities are limited, an automated quality control system can help to assure a constant quality level. Due to the high production speeds, only an optical measurement can be used. While CCD-camera-based control systems are generally applied in wood working, no approach has been made so far to measure the surface roughness which is caused by the machining of the workpiece. This paper presents two different quality control systems for an assessment of the surface quality of a workpiece. In planing of solid wood, the size of the waves on the surface is most significant for workpiece quality. An image processing system has been developed which measures the width of the waves by means of a special illumination. In machining chipboards, the size and number of cracks in the edge are very important. Here, a camera-based system is presented which is able to measure the complete workpiece edge even at high feed rates with a sufficient resolution.     

In-situ investigation of the kesterite formation from binary and ternary sulphides

The formation of kesterite (Cu₂ZnSnS₄) from different stoichiometric mixtures of binary and ternary sulphides was investigated by in-situ high temperature synchrotron X-ray diffraction. The data were collected during the heating, the annealing and the cooling cycle. The Rietveld analysis of the diffractograms led us to determine temperature dependent phase changes qualitatively and quantitatively as well as the lattice constants of the different phases. Showing exemplarily with the mixture 2CuS + SnS + ZnS the formation of Cu₂ZnSnS₄ starts just below 300 °C. The volume size of the fcc anion substructure of the newly formed kesterite at 300 °C corresponds to the one of the ZnS phase. The lattice parameter of Cu₂ZnSnS₄ increases nonlinearly with increasing temperature showing possibly the trend of different formation stages. Comparing the lattice constants a and c of the several synthesized kesterites at 700 °C among each other and with a pre-synthesized kesterite, remarkable variations were obtained, whereas the ratio of the lattice parameter (c/2a) is comparable. These features led to the assumption that the cation distribution may vary in dependence on temperature and on the phase mixture used as starting material.