Vacuolar (Storage) Proteins of Cocoa Seeds and their Degradation during Germination and Fermentation

Investigations of proteolysis during anaerobic cocoa seed incubation have been extended by disc and SDS-gel electrophoretic protein analysis. Two protein bands (2.6 × 10⁴ and 4.4 × 10⁴ Dalton) were found to be vacuolar storage proteins, which accumulated during seed ripening (90 to 160 days after pollination) and which were specifically utilised during germination. Although the storage proteins are poorly soluble at pH 3.5–4.5, proteolysis during incubation of acetone dry powders is highest in this pH range. All proteins are digested at 50°C, pH 4.5. During seed incubation at 50°C, pH 4.5, however, the storage proteins are degraded preferentially although the cells are dead at 50°C. This degradation is increased by preincubation at 40°C instead of 50°C. The results are discussed in the light of structural peculiarities in the seed tissue and the possible role of specific endopeptidases and peptides in the formation of flavour precursors during fermentation.     

Potential and limits of functional modelling in the CAD process

This paper gives a survey of the beginning and newest computer-aided functional modelling by German researchers. The basic principles of functional modelling are established and a representative function model is illustrated by the example of an emergency power unit. Some important methods for computer-aided modelling according to the function model are explained in detail. Following this the limits of functional modelling are outlined by describing the working arrangements of working principles using a flowchart representation of the function structure.     

Thermal dissociation of urethanes studied by FTIR spectroscopy

The thermal dissociation of urethane groups has been studied by FTIR spectroscopy depending on the type of diisocyanate, the structure of the hard segment and the composition of polyurethane. Independent of the composition and the structure, the dissociation started between 150 and 160°C. Consequently, the dissociation sets in at temperatures below the melting temperature of the model hard segments, i.e. already in the solid state. The NCO absorption band reaches its maximum intensity between 180 and 190°C. This result opposes the references in literature suggesting a four-centre reaction for transurethanization.     

Analyse des Erdbeeraromas - Quantifizierung der flüchtigen Komponenten in Kulturerdbeervarietäten und der Walderdbeere

The volatile components of thirteen strawberry varieties and of a wild strawberry were evaluated in the freon-extract of fresh and frozen fruits. With the aid of GC/MS about 120 volatile substances could be identified. The determination of the substantial sensory qualities resulted from AEDA with sniffing technique. In this way 17 key compounds could be attached. The analysis of the key compounds point out significient variety differences.     

Nondeterminism and boolean operations in pda's

There are nondeterministic context-free languages that cannot be expressed as a Boolean formula over deterministic context-free languages. The closure of the context-free languages under intersection does not yield closure under complementation.     

Kinetic Stabilization of the Sol–Gel State in Perovskites Enables Facile Processing of High‐Efficiency Solar Cells

Perovskite solar cells increasingly feature mixed‐halide mixed‐cation compounds (FA_1?x?yMA_xCs_yPbI_3?zBr_z) as photovoltaic absorbers, as they enable easier processing and improved stability. Here, the underlying reasons for ease of processing are revealed. It is found that halide and cation engineering leads to a systematic widening of the anti‐solvent processing window for the fabrication of high‐quality films and efficient solar cells. This window widens from seconds, in the case of single cation/halide systems (e.g., MAPbI₃, FAPbI₃, and FAPbBr₃), to several minutes for mixed systems. In situ X‐ray diffraction studies reveal that the processing window is closely related to the crystallization of the disordered sol–gel and to the number of crystalline byproducts; the processing window therefore depends directly on the precise cation/halide composition. Moreover, anti‐solvent dripping is shown to promote the desired perovskite phase with careful formulation. The processing window of perovskite solar cells, as defined by the latest time the anti‐solvent drip yields efficient solar cells, broadened with the increasing complexity of cation/halide content. This behavior is ascribed to kinetic stabilization of sol–gel state through cation/halide engineering. This provides guidelines for designing new formulations, aimed at formation of the perovskite phase, ultimately resulting in high‐efficiency perovskite solar cells produced with ease and with high reproducibility.     

Quantitative 13C NMR spectroscopic studies on the equilibrium of formaldehyde with its releasing cosmetic preservatives

The aim of our study was to show that NMR spectroscopy is an excellent method to obtain reliable information about the equilibrium between free formaldehyde and its formaldehyde releasers. For this purpose, we compared several O- and N-formal-based formaldehyde releasers used in industrial and consumer products. The underlying chemical structures as well as the release of formaldehyde were followed quantitatively as a function of the pH and dilution. It was shown that only the amide-based N-formals are a reservoir for formaldehyde in the concentrations normally used in cosmetic products, whereas O-formals and the amine-based N-formals decompose completely. Since NMR spectroscopy does not affect the equilibrium between free and bound formaldehyde, we think that it is the only method for unequivocal determination of free formaldehyde. Measurements on finished products showed that free formaldehyde can be quantified down to concentrations as low as approximately 0.002 wt % in an acceptable measuring time.