Chemical and Structural Investigations of Biomimetically Grown Fluorapatite–Gelatin Composite Aggregates

Deeper understanding of the basic principles of biomineralization is a major challenge for present and future research. The high complexity of in‐vivo conditions calls for simplified model systems that still involve dynamic processes like reorganization, formation, self‐organization, and development of patterns, respectively. The present contribution deals with hierarchically ordered spherical aggregates of fluorapatite–gelatin composites with fractal architecture that are grown in gelatin matrices. The model system was chosen to mimic formation conditions on a lower level of complexity compared with the natural formation of calcified tissue (bone, teeth). In order to gain insight into structure formation and the motif for this special kind of morphogenesis we investigated the interaction of the organic and inorganic components of aggregates in different growth stages by detailed chemical analyses, thermoanalytical measurements, X‐ray diffraction on solitary particles, and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) investigations. The close relation of the results and observations to calcified tissue may stimulate advanced interests in the fields of medical and materials development.     

Technological learning in bioenergy systems

The main goal of this article is to determine whether cost reductions in different bioenergy systems can be quantified using the experience curve approach, and how specific issues (arising from the complexity of biomass energy systems) can be addressed. This is pursued by case studies on biofuelled combined heat and power (CHP) plants in Sweden, global development of fluidized bed boilers and Danish biogas plants. As secondary goal, the aim is to identify learning mechanisms behind technology development and cost reduction for the biomass energy systems investigated. The case studies reveal large difficulties to devise empirical experience curves for investment costs of biomass-fuelled power plants. To some extent, this is due to lack of (detailed) data. The main reason, however, are varying plant costs due to differences in scale, fuel type, plant layout, region etc. For fluidized bed boiler plants built on a global level, progress ratios (PRs) for the price of entire plants lies approximately between 90–93% (which is typical for large plant-like technologies). The costs for the boiler section alone was found to decline much faster. The experience curve approach delivers better results, when the production costs of the final energy carrier are analyzed. Electricity from biofuelled CHP-plants yields PRs of 91–92%, i.e. an 8–9% reduction of electricity production costs with each cumulative doubling of electricity production. The experience curve for biogas production displays a PR of 85% from 1984 to the beginning of 1990, and then levels to approximately 100% until 2002. For technologies developed on a local level (e.g. biogas plants), learning-by-using and learning-by-interacting are important learning mechanism, while for CHP plants utilizing fluidized bed boilers, upscaling is probably one of the main mechanisms behind cost reductions.     

Isotropic Constitutive Model for Sintering Particle Packings

This paper presents an isotropic model for the effective viscosities of sintering particle packings. The relationship between the macroscopic stress and deformation rate is based on the behavior of individual interparticle contacts, represented by contact viscosities, and the statistics of the packing. The contact viscosities depend on the contact area, which is the primary variable used to describe the state of the packing. A direct consequence of this choice of state variable is that the effective viscosities are identically zero for an undeformed and unsintered packing. Specific results are presented for the case of Newtonian viscous materials. The model is compared with existing models for porous Newtonian viscous materials. Experiments conducted with spherical glass powder packings show good agreement with the model. Finite-element simulations using the model have been used to study forging of a pellet.     

EXTRACTION OF LIGNITE WITH TOLUENE IN SUB- AND SUPERCRITICAL STATES

Nine Chinese lignite samples were extracted with toluene using a nonisothermal experimental technique at sub- and supercritical conditions in a semi-continuous apparatus. The effects of lignite properties, pressure, and H-donor solvent on the yields were investigated.

The results show that the oil yield is about 1.8 to 2.7 times that of Fischer assay and the conversion and extract yield increase linearly with the increase of volatile matter of lignite and pressure. When a H-donor solvent (tetraline) is added to the solvent (toluene), the conversion and extract yield are increased.     

I love you, that’s why I ignore you.

How does the analyst understand his or her patient’s lack of response to events precipitated by the analyst, especially absences? The author offers an explanation based on a unique form of caring. A. Green’s (1972) concept of the dead mother is crucial to this understanding, as is the distinction among hate, love, and care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Efficient New Pyrimidine Synthesis – a pathway to octupoles

The condensation of N,N,N′-tris(trimethylsilyl)-amidines ( 6 , 11 , 22 ) with vinamidinium salts ( 1 , 7 ) in the presence of potassium fluoride is the method of choice for the synthesis of pyrimidines ( 8 , 12 , 20 , 23 ). Octupoles comprising 1,3,5-benzene ( 8 ) and triphenylamine ( 12 , 20 ) derivatives can be prepared in high yields.     

Säurekatalysierte Umsetzungen von Aromaten mit Alkanen und Cycloalkanen. IX. Alkylierungen mit 2,2,4-Trimethylpentan (Isooctan)

Acid-catalyzed Reactions of Aromatic Hydrocarbons with Alkanes and Cycloalkanes. IX. Alkylations with 2,2,4-Trimethylpentane (Isooctane) The non-conventional alkylation of benzene, toluene, ethyl- and isopropylbenzene, fluoro- and chlorobenzene with 2,2,4-trimethylpentane in the presence of acid catalysts is described. The composition of the rather complex reaction mixtures is determined by gas-liquid chromatography and mass spectrometry, tert. butylarenes being the main products beside alkylsubstituted indanes and tetralines. Their formation is interpreted as a competition between fragmentation and isomerization of the alkylating agent. By use of trifluoromethanesulfonic acid or combinations of catalysts from HF or HSO₃F with variant metallic fluorides at lower temperatures the selectivity of the reaction may be partially raised.     

Partialsynthesen von Cardenoliden und Cardenolid-Analogen. IX. Cardenolidderivate mit einer ungesättigten Aldehydfunktion am Lactonring

Partial Syntheses of Cardenolides and Cardenolide Analogues. IX. Cardenolide Derivatives with an Unsaturated Aldehyde Function at the Lactone Ring Oxidation of 22-allyl-digitoxigenin-3-acetate [ 1 ] and 22-allyl-digitoxin ( 4 ) with selenium dioxide resulted in the introduction of an oxygen function into the unsaturated C-22 substituent of the cardenolide molecule. The isolated compounds were the 22-(3′-oxo-prop-1′-en-1′-yl)-derivatives 3 and 6 of 1 and 4 , respectively. The molecular biological activity of 3 was estimated to be about six times higher than that of the parent compound 1 .