Analysis of free amino acids in green coffee beans

To investigate amino acid changes in green coffee beans in the post-harvest period, amino acid concentrations were determined in green beans and after modelled drying, fermentation and storage. After the drying at alternating temperatures up to maximally 40°C, considerable changes in the concentrations of individual amino acids were identified. At the beginning of the storage period, significant changes in concentration were found to a minor extent. Under the condition of drying, it was mainly the concentration of glutamic acid that changed considerably. There was an increase in all the samples by 500 mg/kg dry matter on average, which corresponds to an increase of about 50% of the original value. In contrast, the concentration of aspartic acid in most of the samples decreased clearly due to drying. For the predominant part of the coffee samples, there was a significant increase in the hydrophobic amino acids Val, Phe, Ile and Leu. Changes of the quantities of other amino acids were non-uniform and only insignificant. Constant drying at 80°C for most of the amino acids brought about only minor concentration changes compared to those values obtained at 40°C. Modelled fermentation had no significant effect on the concentrations of the individual amino acids. After a 4-week storage of dried beans, amino acid concentrations did not change further. It is very possible that different post-harvest treatment parameters may influence the amount of aroma precursor compounds in the coffee beans.     

R-phase formation in Ti39Ni45Cu16 shape memory thin films and bulk alloys discovered by combinatorial methods

The combinatorial fabrication and high-throughput characterization of a Ti–Ni–Cu shape memory thin film composition spread led to the discovery of the shape memory alloy Ti₃₉Ni₄₅Cu₁₆, which exhibits a single B2 → R-phase transformation above 25 °C with a thermal hysteresis width <1 K. Here we show that the thin film results correctly predict the phase transformation behavior of bulk material upon cooling from the high temperature phase. For both thin film and bulk, a two-step B2 → R-phase → B19′ transformation was found. The B2 → R-phase transformation can be exploited independently, due to a significant temperature separation of the two transformation steps. The shape memory effect in both thin film and bulk samples is limited due to the two-phase microstructure. Transmission electron microscopy investigations revealed the existence of Ti(Ni,Cu)₂ precipitates within the TiNi(Cu) matrix, which are concluded to be responsible for the R-phase formation and separation of the transformation steps.     

Effect of Ionic Substitution on the Thermal Expansion of ZrTiO4

New oxide compounds with α-PbO₂ structure have been synthesized by solid-state reactions. These are derived from ZrTiO₄ and HfTiO₄ by a different kind of ionic substitution. The thermal expansion behavior of these phases was investigated by means of a dilatometer and an X-ray heating diffractometer. These measurements revealed rather low expansion for some of the Zr(Me³⁺/Me⁵⁺)O₄, solid solutions. This behavior is attributed to their high expansion anisotropy, which leads to extended formation of microcracks.     

Dimensional changes during solvent-induced crystallization of poly(ethylene terephthalate) films

The sample dimensional changes accompanying diffusion with induced crystallization in amorphous poly(ethylene terephthalate) (PET) films are analyzed. Initially, the film's lateral area remains practically constant, but near the end of the process, it increases rapidly, consistent with non-Fickian models for diffusion. The ultimate relative thickness increase is about double that for the lateral dimension, implying that plastic deformation in the thickness direction accompanies the sorption. Plots of fractional area increase (ΔA/ΔA_∞) vs. fractional weight gain (W/W_∞) indicate severe softening of the polymer by the penetrant.     

Chemical modification of polyester fiber surfaces by amination reactions with multifunctional amines

The feasibility of incorporating amine groups into the surface of polyester (PET) fibers by reaction with multifunctional amines was investigated. Reactions of diethylenetriamine (DETA), trethylenetetramine (TETTA), and tetraethylenepentamine (TTEPA) with PET monofilaments and with a multifilament yarn were studied. Microspectrophotometric examination of aminated fibers stained with an acid dye at low pH revealed the location and concentration of amine groups. Amination could be confined to the periphery and was found to be uniform on the fiber surface. The rate of the reaction, as revealed by acid dye staining, was characterized by an induction period followed by an autoaccelerated stage. Extent of incorporation of amine groups was found to be similar for the three amines. There is a significant improvement in water wettability due to surface amination, and the interfacial shear strength of TTEPA-treated PET monofilaments embedded in an epoxy resin matrix was almost doubled. As the amination reaction proceeds, there is a weakening of the reacted zone in the PET due to chain scission leading to a decrease in the interfacial shear strength. Scanning electron microscopy (SEM) studies revealed that failure occurred within the filament most probably between the reacted and unreacted zones. The tensile properties of the TTEPA-treated PET filaments were hardly affected at the investigated extents of amination.     

PSICO: Solving Protein Structures with Constraint Programming and Optimization

In this paper we propose PSICO (Processing Structural Information with Constraint programming and Optimisation) as a constraint-based approach to determining protein structures compatible with distance constraints obtained from Nuclear Magnetic Resonance (NMR) data. We compare the performance of our proposed algorithm with DYANA (Dynamics algorithm for NMR applications) an existing commercial application based on simulated annealing. On a test case with experimental data on the dimeric protein Desulforedoxin, the method proposed here supplied similar results in less than 10 minutes compared to approximately 10 hours of computation time for DYANA. Although the quality of results can still be improved, this shows that CP technology can greatly reduce computation time, a major advantage because structural NMR technique generally demands multiple runs of structural computation.