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With the observation of superconductivity at ambient pressure conditions in B doped Si in 2006 [1] and Ga doped Ge [2] the group-IV semiconductors become of interest for future information processing technologies like quantum computing. To achieve the high doping levels needed for superconductivity non-equilibrium doping techniques like gas immersion laser doping or ion implantation and short term annealing are needed. Only the latter one is fully compatible to standard microelectronic technology. In a new approach we implanted a Ga concentration up to 11 at.% through a 30 nm SiO2 cover layer into commercial Si and Ge wafers [3-6]. During annealing a thin superconducting Ga-rich nanolayer is formed at the SiO2/semiconductor interface. These layers show promising superconducting properties (TC = 7 K, BC < 8 T, jC < 50 kA/cm2). Detailed microstructural investigations by means of XTEM and RBS/C will be discussed. Recent results show the adjustability of the superconducting properties. We are able to produce superconducting microstructures having a width of 3 µm and used the FIB to implement a Josephson junction as key element for a prospective SQUID. [1] E. Bustarret et al., Nature 444 (2006) 465 [2] T. Herrmannsdörfer et al., Phys, Rev. Lett. 102 (2009) 217003 [3] R. Skrotzki et al., Appl. Phys. Lett. 97 (2010) 192505 [4] J. Fiedler et al., Phys. Rev. B 83 (2011) 214504 [5] J. Fiedler et al., Phys. Rev. B 85 (2012) 134530 [6] V. Heera et al., Appl. Phys. Lett. 100 (2012) 262602

Superconducting layers in silicon and germanium are fabricated via gallium implantation through a thin SiO2 cover layer and subsequent rapid thermal annealing. Gallium accumulation at the SiO2/Si and SiO2/Ge interfaces is observed but no pure gallium phases were found. In both cases superconducting transition occurs around 6 – 7 K which can be attributed to the metallic conduct-ing, gallium rich interface layer. However, the superconducting as well as the normal-state transport properties in gallium overdoped silicon or germanium are different.

Transparent metal-semiconductor field-effect transistors (MESFETs) with a ZnCoO channel have been fabricated by pulsed laser deposition on c-plane sapphire substrates at a temperature of 550 degrees C. The paramagnetic properties have been confirmed by magnetotransport measurements on undepleted ZnCoO films without Schottky gate contacts. The Au/AgxO Schottky gate contacts were processed by optical lithography and metallization. Below 50 K, the MESFET characteristics are persistently changed from a low resistance state (LRS) to high resistance state by an external magnetic field. The MESFET can be switched back into the LRS only by heating it up to room temperature.

Item does not contain fulltext, The exon-junction complex (EJC) performs essential RNA processing tasks. Here, we describe the first human disorder, thrombocytopenia with absent radii (TAR), caused by deficiency in one of the four EJC subunits. Compound inheritance of a rare null allele and one of two low-frequency SNPs in the regulatory regions of RBM8A, encoding the Y14 subunit of EJC, causes TAR. We found that this inheritance mechanism explained 53 of 55 cases (P < 5 x 10(-228)) of the rare congenital malformation syndrome. Of the 53 cases with this inheritance pattern, 51 carried a submicroscopic deletion of 1q21.1 that has previously been associated with TAR, and two carried a truncation or frameshift null mutation in RBM8A. We show that the two regulatory SNPs result in diminished RBM8A transcription in vitro and that Y14 expression is reduced in platelets from individuals with TAR. Our data implicate Y14 insufficiency and, presumably, an EJC defect as the cause of TAR syndrome.

Heavily Ga implanted Si nanolayers covered with a thin SiO2 layer exhibit a superconductor-insulator transition in dependence on annealing conditions. The transition characteristics resemble those of ultrathin quench-condensed metal films although the implanted layer differs clearly in composition, width, and nanostructure. This implies a general physical mechanism for the superconductor-insulator transition in thin, disordered layers which is supposed to be a quantum phase transition between dual states - the superconducting and the superinsulating one. The existence of a critical resistance for the phase transition is confirmed.

Initiated by the finding of doping-induced ambient-pressure superconductivity in classic group-IV semiconductors, in particular our investigation on Ga-doped Germanium [1], we have succeeded in preparing an even more promising candidate for superconducting onchip application [2]. Ion implantation has been utilized to introduce a high dose of Ga into silicon wafers capped by 30 nm SiO2. Ga segregation underneath the cover was stimulated by subsequent rapid thermal annealing in a narrow time and temperature window. Extended structural investigations by means of XTEM, EDX, RBS/C, and SIMS confirm a reproducible formation of 10 nm thin amorphous Ga-rich layers. In the normal state these layers reveal a sheet resistance with a negative temperature derivative and an absolute value close to the quantum resistance which is about 6 kOhm. The superconducting onset temperature accounts for up to 10 K while a zero-resistance state coincides with diamagnetic screening below 5 K verified by means of resistivity and dc magnetization measurements. Further, superconductivity remains stable up to remarkable high magnetic fields of more than 8 Tesla and exhibits a distinct critical-field anisotropy manifesting its thin-film character. Homogeneity and scale-independent behavior down to 3 micron have been proven by lateral microstructuring via photolithography rendering critical-current densities higher than 50 kA/cm2. Recently, focussed-ion beam technique has been implemented in order to create Josephson junctions - key elements of the prospective first ever built gallium SQUID.

BACKGROUND: Myocardial infarction leads to cardiac remodeling and development of heart failure. Insufficient myocardial capillary density after myocardial infarction has been identified as a critical event in this process, although the underlying mechanisms of cardiac angiogenesis are mechanistically not well understood. METHODS AND RESULTS: Here, we show that the small noncoding RNA microRNA-24 (miR-24) is enriched in cardiac endothelial cells and considerably upregulated after cardiac ischemia. MiR-24 induces endothelial cell apoptosis, abolishes endothelial capillary network formation on Matrigel, and inhibits cell sprouting from endothelial spheroids. These effects are mediated through targeting of the endothelium-enriched transcription factor GATA2 and the p21-activated kinase PAK4, which were identified by bioinformatic predictions and validated by luciferase gene reporter assays. Respective downstream signaling cascades involving phosphorylated BAD (Bcl-XL/Bcl-2-associated death promoter) and Sirtuin1 were identified by transcriptome, protein arrays, and chromatin immunoprecipitation analyses. Overexpression of miR-24 or silencing of its targets significantly impaired angiogenesis in zebrafish embryos. Blocking of endothelial miR-24 limited myocardial infarct size of mice via prevention of endothelial apoptosis and enhancement of vascularity, which led to preserved cardiac function and survival. CONCLUSIONS: Our findings indicate that miR-24 acts as a critical regulator of endothelial cell apoptosis and angiogenesis and is suitable for therapeutic intervention in the setting of ischemic heart disease. [KEYWORDS: Animals, Apoptosis/drug effects, Arterioles/pathology, Capillaries/pathology, Cell Hypoxia, Cells, Cultured/drug effects/metabolism, Collagen, Drug Combinations, Drug Evaluation, Preclinical, Endothelial Cells/ metabolism/pathology, GATA2 Transcription Factor/biosynthesis/genetics, Gene Expression Profiling, Heart Failure/etiology, Heme Oxygenase-1/bi, BACKGROUND: Myocardial infarction leads to cardiac remodeling and development of heart failure. Insufficient myocardial capillary density after myocardial infarction has been identified as a critical event in this process, although the underlying mechanisms of cardiac angiogenesis are mechanistically not well understood. METHODS AND RESULTS: Here, we show that the small noncoding RNA microRNA-24 (miR-24) is enriched in cardiac endothelial cells and considerably upregulated after cardiac ischemia. MiR-24 induces endothelial cell apoptosis, abolishes endothelial capillary network formation on Matrigel, and inhibits cell sprouting from endothelial spheroids. These effects are mediated through targeting of the endothelium-enriched transcription factor GATA2 and the p21-activated kinase PAK4, which were identified by bioinformatic predictions and validated by luciferase gene reporter assays. Respective downstream signaling cascades involving phosphorylated BAD (Bcl-XL/Bcl-2-associated death promoter) and Sirtuin1 were identified by transcriptome, protein arrays, and chromatin immunoprecipitation analyses. Overexpression of miR-24 or silencing of its targets significantly impaired angiogenesis in zebrafish embryos. Blocking of endothelial miR-24 limited myocardial infarct size of mice via prevention of endothelial apoptosis and enhancement of vascularity, which led to preserved cardiac function and survival. CONCLUSIONS: Our findings indicate that miR-24 acts as a critical regulator of endothelial cell apoptosis and angiogenesis and is suitable for therapeutic intervention in the setting of ischemic heart disease. [KEYWORDS: Animals, Apoptosis/drug effects, Arterioles/pathology, Capillaries/pathology, Cell Hypoxia, Cells, Cultured/drug effects/metabolism, Collagen, Drug Combinations, Drug Evaluation, Preclinical, Endothelial Cells/ metabolism/pathology, GATA2 Transcription Factor/biosynthesis/genetics, Gene Expression Profiling, Heart Failure/etiology, Heme Oxygenase-1/bi

Since superconductivity has been discovered one century ago, scientists search for new materials that show this fascinating ground state of matter. Recent investigations on superconductivity of elemental group-IV semiconductors like diamond [1] and silicon [2] lead to a new debate about the mechanism and technological potential of these unusual superconductors. In our previous work, we have shown the possibility of creating highly Ga doped Ge layers via Ga-ion implantation and subsequent short-time annealing. As a consequence of the high doping level, these layers are intrinsically superconducting below 1 K [3]. Furthermore we investigated the feasibility of embedding superconducting layers in Si-SiO2 heterostructures not via doping but by Ga precipitation reaching critical temperatures of 7 K [4] with equivalent processing steps. From these investigations, the question arises if it is possible to combine highly doped semiconducting regions with intrinsic and extrinsic superconducting structures having different critical temperatures. We used again Ga implantation in Ge covered by a 30 nm SiO2 layer and flash-lamp annealing to create a complex layer structure showing various transitions in different superconducting states. The first transition occurs at 7 K and can be attributed to Ga-rich precipitates at the Ge-SiO2 interface. Due to the superconductivity of the underlying highly doped germanium layer, a second transition is observed at around 1 K. Recent results on the structural and electrical properties of the heterostructures will be presented. [1] E. A. Ekimov et al., Nature (London) 428, 542 (2004). [2] E. Bustarret et al., Nature 444, 465 (2006). [3] T. Herrmannsdörfer et al., Phys, Rev. Lett. 102, 217003 (2009); V. Heera et al., Journal of Applied Physics 107, 053508 (2010). [4] J. Fiedler et al., Phys. Rev. B 83, 214504 (2011); R. Skrotzki et al., Appl. Phys. Lett. 97 192505 (2010).

Recently a lot of research has been done in revealing the nature of intrinsic superconductivity in highly p-type doped silicon and germanium. However, the studies presented here, demonstrate the feasibility of embedding extrinsic superconducting nanolayers in commercial (100) silicon wafers due to Ga precipitation. With the ion implantation technique a high Ga fluence (2x1016 cm-2 or 4x1016 cm-2) is introduced in Si through a 30 nm SiO2 cover layer. This leads to amorphous layers containing Ga peak concentrations far beyond the equilibrium solid solubility limit. To initiate Ga precipitation and recrystallization rapid thermal annealing (RTA) is used. At optimized processing conditions (4x1016 cm-2, 600 - 700°C) the samples become superconducting. Critical temperatures of 7 K and in plane critical fields up to 14 T are reached [1]. A detailed investigation of the layer microstructure by means of RBS/C and TEM will be presented. These structural investigations reveal polycrystalline Si layers containing amorphous Ga-rich precipitates and that the superconductivity arises because of a high density of precipitates at the Si/SiO2 interface. As the ion implantation with subsequent annealing is compatible with standard microelectronic technology it could be possible to develop new superconducting devices, which operate above liquid He temperature. [1] Skrotzki R. et al., Appl. Phys. Lett. 97 (2010) 192505

Implant infection still represents a major clinical problem in orthopedic surgery. We therefore tested the in vitro biocompatibility and antibacterial effects of copper (Cu)- and silver (Ag)-ion implantation. Discs of a commonly used titanium alloy (Ti6AlV4) with an aluminium oxide-blasted surface were treated by Cu- or Ag-ion implantation with different dosage regimen (ranging from 1e15-17 ions cm(-2) at energies of 2-20 keV). The samples were seeded with primary human osteoblasts and cell attachment and proliferation was analyzed by an MTT-assay. In comparison to the reference titanium alloy there was no difference in the number of attached viable cells after two days. After seven days the number of viable cells was increased for Cu with 1e17 ions cm(-2) at 2 and 5 keV, and for Ag with 1e16 ions cm(-2) at 5 keV while it was reduced for the highest amount of Ag deposition (1e17 ions cm(-2) at 20 key). Antibacterial effects on S.aureus and E.coli were marginal for the studied dosages of Cu but clearly present for Ag with 1e16 ions cm(-2) at 2 and 5 keV and 1e17 ions cm(-2) at 20 keV. These results indicate that Ag-ion implantation may be a promising methodological approach for antibacterial functionalization of titanium implants.

We report new experimental results on how superconductivity in gallium-doped germanium (Ge:Ga) is influenced by hole concentration and microstructure. Ion implantation and subsequent flash-lamp annealing at various temperatures have been utilized to prepare highly p-doped thin films consisting of nanocrystalline and epitaxially grown sublayers with Ga-peak concentrations of up to 8 at.%. Successive structural investigations were carried out by means of Rutherford-backscattering spectrometry in combination with ion channelling, secondaryion-mass spectrometry, and high-resolution cross-sectional transmission electron microscopy. Hole densities of 1.8·1020 to 5.3·1020 cm-3 (0.4 to 1.2 at.%) were estimated via Hall-effect measurements revealing that only a fraction of the incorporated gallium has been activated electrically to generate free charge carriers. The coincidence of a sufficiently high hole and Ga concentration is required for the formation of a superconducting condensate. Our data reflect a critical hole concentration of around 0.4 at.%. Higher concentrations lead to an increase of Tc from 0.24 to 0.43 K as characterized by electrical-transport measurements. A short mean-free path indicates superconductivity in the dirty limit. In addition, small critical-current densities of max. 20 kA/m2 point to a large impact of the microstructure

Superconducting nanolayers in Ge and Si can be fabricated by high fluence Ga ion implantation and subsequent rapid thermal annealing.

Es konnte gezeigt werden, dass neben Diamant auch die technologisch relevanten Gruppe-IV-Halbleiter Si und Ge im extrem hochdotierten Zustand supraleitend werden. Am Helmholtz – Zentrum Dresden – Rossendorf ist es erstmalig gelungen, supraleitfähige Ge-Schichten in einem zu Fertigungsverfahren der Mikroelektronik kompatiblen Dotierprozess, bestehend aus Ga-Ionenimplantation und Kurzzeitausheilung, herzustellen. Die hochdotierten Ge-Schichten zeigen intrinsische Supraleitung mit kritischen Temperaturen bis zu 1 K. Eine weitere Erhöhung der Dotierkonzentration und damit der kritischen Temperatur ist aufgrund der begrenzten Löslichkeit von Ga in Ge (1 at.%) sehr schwierig. Um dennoch höhere Sprungtemperaturen zu erreichen, wurden die geringe Löslichkeit von Ga in Si (0.1 at.%) sowie die supraleitenden Eigenschaften von Ga ausgenutzt. In Ga implantiertem Si bilden sich Ausscheidungen, wodurch vergrabene, extrinsisch supraleitende Ga reiche Schichten hergestellt werden können. Die kritische Temperatur ist mit 7 K deutlich höher als in dotiertem Ge. Die Struktur der Proben wurde mit Rutherford Rückstreuspektrometrie (RBS), Transmissionselektronenmikroskopie (TEM) sowie Sekundärionen-Massenspektrometrie (SIMS) untersucht. Für die elektrische Charakterisierung wurden Temperaturen zwischen 100 mK und 400 K sowie Magnetfelder bis 9 T verwendet. Im Vortrag werden die Grundzüge der Dotierung mittels Ionenimplantation sowie die Ergebnisse elektrischer und struktureller Untersuchung beider Materialsysteme vorgestellt.

Multi-group method is an accepted technique for approximately solving the equation of radiative transfer. In this paper, group averaged transfer scattering cross sections, required for solving the equation of radiative transfer in a multi-group approach, are presented. Compton scattering is approximately described by the Compton cross section for free electrons at rest. In the low photon energy limit analytical results for scattering coefficients have been derived., Comment: 14 pages, 15 tables

We report on superconducting properties of gallium-enriched silicon layers in commercial (100) oriented silicon wafers. Ion implantation and subsequent rapid thermal annealing have been applied for realizing gallium precipitation beneath a silicon-dioxide cover layer. Depending on the preparation parameters, we observe a sharp drop to zero resistance at 7 K. The critical-field anisotropy proofs the thin-film character of superconductivity. In addition, out-of-plane critical fields of above 9 T and critical current densities exceeding 2 kA/cm2 promote these structures to be possible playgrounds for future microelectronic technology