Experiment K-6-22. Growth hormone regulation, synthesis and secretion in microgravity. Part 1: Somatotroph physiology. Part 2: Immunohistochemical analysis of hypothalamic hormones. Part 3: Plasma analysis

The objectives of the 1887 mission were: (1) to determine if the results of the SL-3 pituitary gland experiment (1) were repeatable; and (2) to determine what effect a longer mission would have on the rat pituitary gland growth hormone (GH) system. In the 1887 experiment two issues were considered especially important. First, it was recognized that cells prepared from individual rat pituitary glands should be considered separately so that the data from the 5 glands could be analyzed in a statistically meaningful way. Second, results of the SL-3 flight involving the hollow fiber implant and HPLC GH-variant experiments suggested that the biological activity of the hormone had been negatively affected by flight. The results of the 1887 experiment documented the wisdom of addressing both issues in the protocol. Thus, the reduction in secretory capacity of flight cells during subsequent extended cell culture on Earth was documented statistically, and thereby established the validity of the SL-3 result. The results of both flight experiments thus support the contention that there is a secretory lesion in pituitary GH cells of flight animals. The primary objective of both missions was a clear definition of the effect of spaceflight on the GH cell system. There can no longer be any reasonable doubt that this system is affected in microgravity. One explanation for the reason(s) underlying the better known effects of spaceflight on organisms, viz. changes in bone, muscle and immune systems may very well rest with such changes in bGH. In spite of the fact that rats in the Cosmos 1887 flight were on Earth for two days after flight, the data show that the GH system had still not recovered from the effects of flight. Many questions remain. One of the more important concerns the GRF responsiveness of somatotrophs after flight. This will be tested in an upcoming experiment

A proposal of a UCN experiment to check an earthquake waves model

Elastic waves with transverse polarization inside incidence plane can create longitudinal surface wave (LSW) after reflection from a free surface. At a critical incidence angle this LSW accumulates energy density, which can be orders of magnitude higher than energy density of the incident transverse wave. A specially arranged vessel for storage of ultracold neutrons (UCN) can be used to verify this effect.Comment: 8 pages 3 figures added a paragraph on vibrations along surface at critical angl

Those wonderful elastic waves

We consider in a simple and general way elastic waves in isotropic and anisotropic media, their polarization, speeds, reflection from interfaces with mode conversion, and surface waves. Reflection of quasi transverse waves in anisotropic media from a free surface is shown to be characterized by three critical angles.Comment: 11 Figures 26 page

Wide band-gap tuning Cu2ZnSn1-xGexS4 single crystals: Optical and vibrational properties

The linear optical properties of Cu2ZnSn1-xGe x S4 high quality single crystals with a wide range of Ge contents (x=0.1, 0.3, 0.5, 0.7, 0.9 and 1) have been investigated in the ultraviolet and near infrared range using spectroscopic ellipsometry measurements. From the analysis of the complex dielectric function spectra it has been found that the bandgap E 0 increases continuously from 1.49eV to 2.25eV with the Ge content. Furthermore, the evolution of the interband transitions E 1A and E 1B has been also determined. Raman scattering using three different excitation wavelengths and its analysis have been performed to confirm the absence of secondary phases in the samples, and to distinguish between stannite, wurtzite, wurzstannite and kesterite structures. Additionally, the analysis of the high resolution Raman spectra obtained in samples with different [Ge]/([Ge]+[Sn]) ratios allows describing a bimodal behavior of the dominant A modes. The understanding of the incorporation of Ge into the Cu2ZnSnS4 lattice is fundamental in order to develop efficient bandgap engineering of these compounds towards the fabrication of kesterite based solar cells with enhanced performanceThis work was supported by the Marie Curie-ITN project (KESTCELL, GA: 316488), Marie Curie-IRSES project (PVICOKEST, GA: 269167), AMALIE (TEC2012-38901-C02-01) and SUNBEAM (ENE2013-49136-C4-3-R) project funded by the Spanish Ministry of Economy and Competitiveness. RC acknowledges financial support from Spanish MINECO within the Ramón y Cajal program (RYC-2011-08521

Spectroscopic ellipsometry study of Cu2ZnSnS4 bulk poly-crystals

The linear optical properties of Cu2ZnSnS4 bulk poly-crystals have been investigated using spectroscopic ellipsometry in the range of 1.2-4.6 eV at room temperature. The characteristic features identified in the optical spectra are explained by using the Adachi analytical model for the interband transitions at the corresponding critical points in the Brillouin zone. The experimental data have been modeled over the entire spectral range taking into account the lowest E0 transition near the fundamental absorption edge and E1A and E1B higher energy interband transitions. In addition, the spectral dependences of the refractive index, extinction coefficient, absorption coefficient, and normal-incidence reflectivity values have been accurately determined and are provided since they are essential data for the design of Cu2ZnSnS4 based optoelectronic devicesThe research leading to the presented results was partially supported by the European Project INFINITE-CELL (Ref. H2020-MSCA-RISE-2017-777968, 2017–2021, www.infinitecell.eu) and the Spanish MINECO Projects “WINCOST” (ENE2016-80788-C5-2-R) and PHOTOMANA (TEC2015- 69916-C2-1-R). The authors from the Institute of Applied Physics appreciate the financial support from STCU 6224 and from the Institutional Project No. CSSDT 15.817.02.04

Towards the growth of Cu2ZnSn1-xGexS4 thin films by a single-stage process: Effect of substrate temperature and composition

Cu2ZnSn1-xGexS4 (CZTGS) thin films prepared by flash evaporation of a Zn-rich Cu2ZnSn0.5Ge0.5S4 bulk compound in powder form, and a subsequent thermal annealing in S containing Ar atmosphere are studied. The effect of the substrate temperature during evaporation and the initial composition of the precursor powder on the growth mechanism and properties of the final CZTGS thin film are investigated. The microstructure of the films and elemental depth profiles depend strongly on the growth conditions used. Incorporation of Ge into the Cu2ZnSnS4 lattice is demonstrated by the shift of the relevant X-ray diffraction peaks and Raman vibrational modes towards higher diffraction angles and frequencies respectively. A Raman mode at around 348-351 cm-1 is identified as characteristic of CZTGS alloys for x = [Ge]/([Sn]+[Ge]) = 0.14-0.30. The supply of Ge enables the reduction of the Sn loss via a saccrifical Ge loss. This fact allows increasing the substrate temperature up to 350º C during the evaporation, forming a high quality kesterite material and therefore, reducing the deposition process to one single stageRC acknowledges financial support from Spanish MINECO within the Ramón y Cajal programme (RYC-2011-08521) and VIR for the Juan de la Cierva fellowship (JCI-2011-10782). GB also acknowledges the CSIC-JAE pre-doctoral program, co-funded by the European Social Fund. This work was supported by the Marie Curie-IRSES project (PVICOKEST, GA: 269167), Marie Curie-ITN project (KESTCELL, GA: 316488), DAAD project (INTERKEST, Ref: 57050358), and MINECO projects (SUNBEAM, ENE2013-49136-C4-3-R) (TEC2012-38901-C02-01). A. Scheu is acknowledged for GDOES measurement

Towards the growth of Cu2ZnSn1 xGexS4 thin films by a single-stage process: Effect of substrate temperature and composition

9 págs.; 7 figs.; 2 tabs.Cu2ZnSn1-xGexS4 (CZTGS) thin films prepared by flash evaporation of a Zn-rich Cu2ZnSn0.5Ge0.5S4 bulk compound in powder form, and a subsequent thermal annealing in S containing Ar atmosphere are studied. The effect of the substrate temperature during evaporation and the initial composition of the precursor powder on the growth mechanism and properties of the final CZTGS thin film are investigated. The microstructure of the films and elemental depth profiles depend strongly on the growth conditions used. Incorporation of Ge into the Cu2ZnSnS4 lattice is demonstrated by the shift of the relevant X-ray diffraction peaks and Raman vibrational modes towards higher diffraction angles and frequencies respectively. A Raman mode at around 348-351 cm-1 is identified as characteristic of CZTGS alloys for x = [Ge]/([Sn]+[Ge]) = 0.14-0.30. The supply of Ge enables the reduction of the Sn loss via a saccrifical Ge loss. This fact allows increasing the substrate temperature up to 350º C during the evaporation, forming a high quality kesterite material and therefore, reducing the deposition process to one single stage & 2015 Elsevier B.V. All rights reserved.RC acknowledges financial support from Spanish MINECO within the Ramón y Cajal programme (RYC-2011-08521) and VIR for the Juan de la Cierva fellowship (JCI-2011-10782). GB also acknowledges the CSIC-JAE Pre-doctoral Program, co-funded by the European Social Fund. This work was supported by the Marie Curie-IRSES Project (PVICOKEST, GA: 269167), Marie Curie-ITN project (KESTCELL, GA: 316488), DAAD project (INTERKEST, Ref: 57050358), and MINECO projects (SUNBEAM, ENE2013-49136-C4-3-R) (TEC2012- 38901-C02-01). A. Scheu is acknowledged for GDOES measurements.Peer Reviewe

Towards the growth of Cu2ZnSn1 xGexS4 thin films by a single stage process Effect of substrate temperature and composition

Cu2ZnSn1-xGexS4 (CZTGS) thin films prepared by flash evaporation of a Zn-rich Cu2ZnSn0.5Ge0.5S4 bulk compound in powder form, and a subsequent thermal annealing in S containing Ar atmosphere are studied. The effect of the substrate temperature during evaporation and the initial composition of the precursor powder on the growth mechanism and properties of the final CZTGS thin film are investigated. The microstructure of the films and elemental depth profiles depend strongly on the growth conditions used. Incorporation of Ge into the Cu2ZnSnS4 lattice is demonstrated by the shift of the relevant X-ray diffraction peaks and Raman vibrational modes towards higher diffraction angles and frequencies respectively. A Raman mode at around 348-351 cm-1 is identified as characteristic of CZTGS alloys for x = [Ge]/([Sn]+[Ge]) = 0.14-0.30. The supply of Ge enables the reduction of the Sn loss via a saccrifical Ge loss. This fact allows increasing the substrate temperature up to 350º C during the evaporation, forming a high quality kesterite material and therefore, reducing the deposition process to one single stageRC acknowledges financial support from Spanish MINECO within the Ramón y Cajal programme (RYC-2011-08521) and VIR for the Juan de la Cierva fellowship (JCI-2011-10782). GB also acknowledges the CSIC-JAE pre-doctoral program, co-funded by the European Social Fund. This work was supported by the Marie Curie-IRSES project (PVICOKEST, GA: 269167), Marie Curie-ITN project (KESTCELL, GA: 316488), DAAD project (INTERKEST, Ref: 57050358), and MINECO projects (SUNBEAM, ENE2013-49136-C4-3-R) (TEC2012-38901-C02-01). A. Scheu is acknowledged for GDOES measurement

ВЫРАЩИВАНИЕ И СВОЙСТВА МОНОКРИСТАЛЛОВ Cu2ZnSnS4

Polycrystalline ingots bridgman grown and by chemical method reactions of gas-transport connections Cu2ZnSnS4 single crystals of different forms: needle-like, plate and prismatic are received. The composition, structure of the grown single crystals was determined and unit cell parameters were calculated. The melt temperature was determined using DTA method. Transmission spectra in the region of intrinsic absorption edge were studied in temperature interval 20-300 K. The band gap width of Cu2ZnSnS4 single crystals was determined, its temperature dependency has been built and the calculation of the indicated dependency has been carried out. It was shown, that the experimental and calculated values are in good correlations.Методом химических газотранспортных реакций выращены монокристаллы соединения Cu2ZnSnS4. Определены состав, структура и температура плавления полученных кристаллов. Исследованы спектры пропускания в области края собственного поглощения в интервале температур 20-300 К. Определена ширина запрещенной зоны указанных кристаллов и построены ее температурные зависимости

Growth, crystal structure, and properties of Cu2Zn1-xCdxSnS4 solid solutions

The phase diagram of the Cu 2 CdSnS 4 –Cu 2 ZnSnS 4 system was constructed using data on differential thermal, X-ray phase and microstructure analysis methods. The diagram can be attributed to the first type according to the Rosebohm classification. The Cu 2 CdSnS 4 –Cu 2 ZnSnS 4 solid solution single crystals were grown by chemical vapor transport using iodine as a transport agent. Their structure and unit cell parameters as well as compositional dependences of lattice parameters, pycnometric, X-ray densities and microhardness were determined. It was found that the Vegard's law is fulfilled in solutions studied