TEMPus VoLA: The timed Epstein multi-pressure vessel at low accelerations.

The field of planetary system formation relies extensively on our understanding of the aerodynamic interaction between gas and dust in protoplanetary disks. Of particular importance are the mechanisms triggering fluid instabilities and clumping of dust particles into aggregates, and their subsequent inclusion into planetesimals. We introduce the timed Epstein multi-pressure vessel at low accelerations, which is an experimental apparatus for the study of particle dynamics and rarefied gas under micro-gravity conditions. This facility contains three experiments dedicated to studying aerodynamic processes: (i) the development of pressure gradients due to collective particle-gas interaction, (ii) the drag coefficients of dust aggregates with variable particle-gas velocity, and (iii) the effect of dust on the profile of a shear flow and resultant onset of turbulence. The approach is innovative with respect to previous experiments because we access an untouched parameter space in terms of dust particle packing fraction, and Knudsen, Stokes, and Reynolds numbers. The mechanisms investigated are also relevant for our understanding of the emission of dust from active surfaces, such as cometary nuclei, and new experimental data will help interpreting previous datasets (Rosetta) and prepare future spacecraft observations (Comet Interceptor). We report on the performance of the experiments, which has been tested over the course of multiple flight campaigns. The project is now ready to benefit from additional flight campaigns, to cover a wide parameter space. The outcome will be a comprehensive framework to test models and numerical recipes for studying collective dust particle aerodynamics under space-like conditions.

Growth and form of planetary seedlings: results from a microgravity aggregation experiment.

The outcome of the first stage of planetary formation, which is characterized by ballistic agglomeration of preplanetary dust grains due to Brownian motion in the free molecular flow regime of the solar nebula, is still somewhat speculative. We performed a microgravity experiment flown onboard the space shuttle in which we simulated, for the first time, the onset of free preplanetary dust accumulation and revealed the structures and growth rates of the first dust agglomerates in the young solar system. We find that a thermally aggregating swarm of dust particles evolves very rapidly and forms unexpected open-structured agglomerates.

[Dye analytical investigations on the polarization microscopy detection of collagen with Sominrot 4B (Part II)]. / Farbstoffanalytische Untersuchungen zum polarisationsmikroskopischen Nachweis von Kollagen mit Solaminrot 4B (Teil II).

We use the disazo dyestuff Solaminrot 4B for the visualization of collagen fibres in the morphological substratum investigated. The dye selectively enhance the birefringency of the fibres. Therefore, the parts of this paper are dealing with the dye properties of 2 charges of Solaminrot 4B produced by Chemie AG Bitterfeld--Wolfen. The 1st charge contain supplementary substances; the 2nd charge is without ones. We used various physicochemical methods, e.g. chromatography, spectroscopy, and electrophoresis. Moreover, we analyzed the solubility of dye in inorganic and organic solventia, the phase dispersion in benzen and octanol, the influence of the dye probes on the pH values of the dye solutions, and so on. The results indicate that the physicochemical properties of both charges investigated by us are partially different. This is important for the application of Sirius Red dyestuffs to the histological staining procedures.

[Analytical dye studies on the polarization microscopic detection of collagen with Solaminrot 4B. I]. / Farbstoffanalytische Untersuchungen zum polarisations-mikroskopischen Nachweis von Kollagen mit Solaminrot 4B (Teil I).

It is known that the birefringency of the collagen fibres is selectively enhanced by staining with Sirius Red. According to experiences, the most authors usually take Sirius Red F3BA as dye. We use the disazo dyestuff Solaminrot 4B produced by VEB Chemiekombinat Bitterfeld. Thus, the present paper is dealing with physicochemical analysis of the dye. We investigated 2 charges of the Solaminrot 4B. The 1st charge contain supplementary substances; the 2nd charge is without ones. It is reported a series of data resulting from chromatographic and spectroscopic investigations.

[Connective tissue of the human fallopian tube mucosa--polarization microscopic detection of collagen using Solaminrot 4B]. / Uber das Bindegewebe der menschlichen Eileiterschleimhaut--Polarisationsmikroskopischer Nachweis von Kollagen mit Solaminrot 4B.

The Picrosirius-polarization method was applied to the selective morphological collagen detection in the human uterine tube. Solaminrot 4B (VEB Chemiekombinat Bitterfeld) was used as dyestuff which enhances the normal birefringency of collagen fibrous material in tissue sections. The results show that the connective tissue of the lamina propria mucosae consists of collagen fibres, namely considerably. The mucosal folds of uterine tubes of younger individuals contain delicate, weaker birefringent fibres stained yellowish-red and red-orange. The folds of oviducts of ageing individuals composed of compact, strong birefringent collagen fibrous material stained intensely red, red-orange, and yellow. This is characteristic of organs in the pre- and postmenopausal periods and in the senium. The findings suggest that the fibrous structures detected selectively in the oviductal mucosa by combinative method of Picrosolamin-staining and polarization microscopy are distinct collagen fibres. The delicate, weaker birefringent fibres could correspond with collagen type III and the thicker, stronger birefringent ones could represent collagen type I.