Similar Datasets
Project description:In this study we probe how prototrophic yeast from different environmental backgrounds respond to perturbing agents presented in the context of a conflicting signal, repletion of glucose after transient deprivation. To assess the contribution of genetic v
2013-03-03 | E-MTAB-1463 | biostudies-arrayexpress
Project description:The first nitridogermanates(III) Ca6 [Ge2 N6 ] and Sr6 [Ge2 N6 ] were synthesized from sodium flux and structurally characterized by powder and single crystal X-ray diffraction, respectively. They crystallize isostructurally to each other and homeotypic to Ca6 [Cr2 N6 ]H in space group R 3‾ . They feature unprecedented, mutually isolated, ethane-like [GeIII 2 N6 ]12- anions in a staggered conformation. The compounds are semiconductors according to resistivity measurements and electronic structure calculations, yielding band gaps of 1.1 eV for Ca6 [Ge2 N6 ] and 0.2 eV for Sr6 [Ge2 N6 ].
| S-EPMC8048604 | biostudies-literature
Project description:Background: LINE-1 elements make up the most abundant retrotransposon family in the human genome. Full-length LINE-1 elements encode their own reverse transcriptase (RT). They are expressed at low levels in normal cells and abundantly in cancer cells. RT down-regulation, by either RNA interference to LINE-1 elements, or by RT inhibitory drugs, was previously found to reduce proliferation and promote differentiation in cancer cells and to antagonize tumor growth in animal models. Results: We report that the RT inhibitor efavirenz effectively inhibit proliferation of a variety of human tumorigenic cell lines while only slightly affecting the proliferation of human normal fibroblast cell line, a difference that nicely matches RT expression in the former cell lines and its lack in the latter. The finding of Alu and LINE-1 containing DNA:RNA hybrid molecules - identified by CsCl density gradients - selectively in cancer but not in normal cells, suggests that RNA transcripts from these retroelements are candidate substrates for reverse transcription. These hybrids disappear in tumor cells treated with efavirenz, under the same conditions which induce an extensive reprogrammed expression profiles for protein-coding genes, microRNAs (miRNAs) and ultraconserved regions (UCRs). The RT-sensitive miRNAs and UCRs are significantly associated with Alus sequences. Conclusions: A novel RT-dependent mechanism governs the balance between single-stranded and double-stranded RNA production. In cancer cells, the abundant LINE-1-encoded RT reverse-transcribes retroelement-derived mRNAs, generating RNA:DNA hybrids. We propose that this impairs the formation of double-stranded RNAs and the ensuing production of small regulatory RNAs, with a direct impact on gene expression. RT inhibition restores the M-^QnormalM-^R small RNA profile and the regulatory networks that depend on them. Thus, the retrotransposon-encoded RT drives an epigenetic mechanism crucial to maintenance of the transformed state in tumor cells.
2014-01-01 | E-MTAB-1735 | biostudies-arrayexpress
Project description:The integration of dislocation-free Ge nano-islands was realized via selective molecular beam epitaxy on Si nano-tip patterned substrates. The Si-tip wafers feature a rectangular array of nanometer sized Si tips with (001) facet exposed among a SiO2 matrix. These wafers were fabricated by complementary metal-oxide-semiconductor (CMOS) compatible nanotechnology. Calculations based on nucleation theory predict that the selective growth occurs close to thermodynamic equilibrium, where condensation of Ge adatoms on SiO2 is disfavored due to the extremely short re-evaporation time and diffusion length. The growth selectivity is ensured by the desorption-limited growth regime leading to the observed pattern independence, i.e. the absence of loading effect commonly encountered in chemical vapor deposition. The growth condition of high temperature and low deposition rate is responsible for the observed high crystalline quality of the Ge islands which is also associated with negligible Si-Ge intermixing owing to geometric hindrance by the Si nano-tip approach. Single island as well as area-averaged characterization methods demonstrate that Ge islands are dislocation-free and heteroepitaxial strain is fully relaxed. Such well-ordered high quality Ge islands present a step towards the achievement of materials suitable for optical applications.
| S-EPMC4778127 | biostudies-literature
Project description:The unique three-dimensional structure of spherical, homoatomic nine-atom germanium clusters opens various possibilities for the spatial arrangement of functional groups. Ligands comprising lone pairs have recently been introduced in the cluster sphere, and we now report the addition of a boranyl group to the cluster featuring a Ge-B exo-cluster bond. The reaction of the twofold-silylated cluster [Ge9 {Si(TMS)3 }2 ]2- (TMS=trimethylsilyl) with 2-chloro-1,3,2-diazaborolidines DABR -Cl leads to the first boranyl-functionalized [Ge9 ] clusters [Ge9 {Si(TMS)3 }2 DABR ]- (R=methyl (1 a), iso-propyl (2 a), ortho-tolyl (3 a)). The anions 2 a and 3 a were structurally characterized as [NHCDipp Cu]+ complexes (NHCDipp =1,3-di(2,6-diisopropylphenyl)imidazolylidine) through single crystal X-ray structure determination. Quantum-chemical calculations manifest the frustrated Lewis pair (FLP) character of the boranyl-functionalized cluster [Ge9 {Si(TMS)3 }2 BCy2 ]- (4 a).
| S-EPMC7898805 | biostudies-literature
Project description:Ge-rich Ge-Sb-Te compounds are attractive materials for future phase change memories due to their greater crystallization temperature as it provides a wide range of applications. Herein, we report the self-assembled Ge-rich Ge-Sb-Te/Sb2Te3 core-shell nanowires grown by metal-organic chemical vapor deposition. The core Ge-rich Ge-Sb-Te nanowires were self-assembled through the vapor-liquid-solid mechanism, catalyzed by Au nanoparticles on Si (100) and SiO2/Si substrates; conformal overgrowth of the Sb2Te3 shell was subsequently performed at room temperature to realize the core-shell heterostructures. Both Ge-rich Ge-Sb-Te core and Ge-rich Ge-Sb-Te/Sb2Te3 core-shell nanowires were extensively characterized by means of scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction, Raman microspectroscopy, and electron energy loss spectroscopy to analyze the surface morphology, crystalline structure, vibrational properties, and elemental composition.
| S-EPMC8707013 | biostudies-literature
Project description:Self-assembled nanocomposites have been extensively investigated due to the novel properties that can emerge when multiple material phases are combined. Growth of epitaxial nanocomposites using lattice-mismatched constituents also enables strain-engineering, which can be used to further enhance material properties. Here, we report self-assembled growth of highly tensile-strained Ge/In0.52Al0.48As (InAlAs) nanocomposites by using spontaneous phase separation. Transmission electron microscopy shows a high density of single-crystalline germanium nanostructures coherently embedded in InAlAs without extended defects, and Raman spectroscopy reveals a 3.8% biaxial tensile strain in the germanium nanostructures. We also show that the strain in the germanium nanostructures can be tuned to 5.3% by altering the lattice constant of the matrix material, illustrating the versatility of epitaxial nanocomposites for strain engineering. Photoluminescence and electroluminescence results are then discussed to illustrate the potential for realizing devices based on this nanocomposite material.
| S-EPMC5290139 | biostudies-literature
Project description:Single crystals of the title compound, octa-iodide deca-anti-monate hexa-tria-conta-germanide, were grown by chemical transport reactions. The structure is isotypic with the analogous clathrates-I. In this structure, the (Ge,Sb)(46) framework consists of statistically occupied Ge and Sb sites that atoms form bonds in a distorted tetra-hedral arrangement. They form polyhedra that are covalently bonded to each other by shared faces. There are two polyhedra of different sizes, viz. a (Ge,Sb)(20) dodeca-hedron and a (Ge,Sb)(24) tetra-cosa-hedron in a 1:3 ratio. The guest atom (iodine) resides inside these polyhedra with symmetry m3 (Wyckoff position 2a) and 2m (Wyckoff position 2d), respectively.
| S-EPMC2979373 | biostudies-literature
Project description:Single crystals of octaiodine henacosarsenic pentacosagermanium were grown by chemical transport reactions. The structure is isotypic with the analogous clathrates-I. In this structure, the statistically occupied clathrand atoms (As,Ge)(46) form bonds in a distorted tetra-hedral coordination and their arrangement can define two polyhedra of different sizes; one is an (As,Ge)(20) penta-gonal dodeca-hedron, and the other is an (As,Ge)(24) tetra-kaideca-hedron. The guest atom (iodine) resides inside these polyhedra with site symmetry m3 (Wyckoff position 2a) and 2m (Wyckoff position 6d), respectively.
| S-EPMC2968696 | biostudies-literature
Project description:Investigating group-IV-based photonic components is a very active area of research with extensive interest in developing complementary metal-oxide-semiconductor (CMOS) compatible light sources. However, due to the indirect band gap of these materials, effective light-emitting diodes and lasers based on pure Ge or Si cannot be realized. In this context, there is considerable interest in developing group-IV based Raman lasers. Nevertheless, the low quantum yield of stimulated Raman scattering in Si and Ge requires large device footprints and high lasing thresholds. Consequently, the fabrication of integrated, energy-efficient Raman lasers is challenging. Here, we report the systematic investigation of stimulated Raman scattering (SRS) in Ge nanowires (NWs) and axial Al-Ge-Al NW heterostructures with Ge segments that come into contact with self-aligned Al leads with abrupt metal-semiconductor interfaces. Depending on their geometry, these quasi-one-dimensional (1D) heterostructures can reassemble into Ge nanowires, Ge nanodots, or Ge nanodiscs, which are monolithically integrated within monocrystalline Al (c-Al) mirrors that promote both optical confinement and effective heat dissipation. Optical mode resonances in these nanocavities support in SRS thresholds as low as 60 kW/cm2. Most notably, our findings provide a platform for elucidating the high potential of future monolithically integrated, nanoscale low-power group-IV-based Raman lasers.
| S-EPMC7322725 | biostudies-literature