173 research outputs found
Synthesis and characterization of microporous titania membranes
A procedure for the preparation of microporous titania membranes by the polymeric sol-gel technique is reported. The influence of acid/titanium ratio, water/titanium ratio, method of mixing components and refluxing time on particle size and sol stability was investigated. The thermal evolution, structural characteristics and liquid permeation properties of calcined materials were studied. Highly reproducible amorphous microporous titania layers with pore sizes le0.8 nm were obtained on both mesoporous gamma-alumina and titania/zirconia coated substrates. The upper limit of thermal stability of the amorphous phase is sim300°C. Higher calcination temperatures led to phase transformation into anatase, which was accompanied by a collapse of the microstructure. The material was found to be chemically stable in a wide pH interval
Local probing of coupled interfaces between two-dimensional electron and hole gases in oxide heterostructures by variable-temperature scanning tunneling spectroscopy
The electronic structure of an epitaxial oxide heterostructure containing two spatially separated two-dimensional conducting sheets, one electronlike (2DEG) and the other holelike (2DHG), has been investigated using variable temperature scanning tunneling spectroscopy. Heterostructures of LaAlO3/SrTiO3 bilayers on (001)-oriented SrTiO3 (STO) substrates provide the unique possibility to study the coupling between subnanometer spaced conducting interfaces. The band gap increases dramatically at low temperatures due to a blocking of the transition from the conduction band of the STO substrate to the top of the valence band of the STO capping layer. This prevents the replenishment of the depleted electrons in the capping layer from the underlying 2DEG and enables charging of the 2DHG by applying a negative sample bias voltage within the band gap region. At low temperatures the 2DHG can be probed separately with the proposed experimental geometry, although the 2DEG is located less than 1 nm belo
Control of oxygen sublattice structure in ultra-thin SrCuO2 films studied by X-ray photoelectron diffraction
Epitaxial and atomically smooth ultra-thin SrCuO2 films are grown on SrTiO3 substrates using pulsed laser deposition. The structural and chemical aspects of these single-layer films of various thickness are characterized using in situ X-ray photoelectron diffraction (XPD) and photoelectron spectroscopy. By comparing XPD scans to multiple-scattering electron diffraction simulations, we demonstrate a structural transformation from bulk-planar to chain-type SrCuO2 as the film thickness is reduced from 9 to 3 unit-cells. This observation is in agreement with the recent theoretical prediction [Z. Zhong, G. Koster, and P. J. Kelly, Phys. Rev. B 85, 121411(R) (2012)] and opens new pathways for structural tuning in ultra-thin films of polar cuprate
Partner independent fusion gene detection by multiplexed CRISPR-Cas9 enrichment and long read nanopore sequencing
Fusion genes are hallmarks of various cancer types and important determinants for diagnosis, prognosis and treatment. Fusion gene partner choice and breakpoint-position promiscuity restricts diagnostic detection, even for known and recurrent configurations. Here, we develop FUDGE (FUsion Detection from Gene Enrichment) to accurately and impartially identify fusions. FUDGE couples target-selected and strand-specific CRISPR-Cas9 activity for fusion gene driver enrichment - without prior knowledge of fusion partner or breakpoint-location - to long read nanopore sequencing with the bioinformatics pipeline NanoFG. FUDGE has flexible target-loci choices and enables multiplexed enrichment for simultaneous analysis of several genes in multiple samples in one sequencing run. We observe on-average 665 fold breakpoint-site enrichment and identify nucleotide resolution fusion breakpoints within 2 days. The assay identifies cancer cell line and tumor sample fusions irrespective of partner gene or breakpoint-position. FUDGE is a rapid and versatile fusion detection assay for diagnostic pan-cancer fusion detection
Imbalance of Power: Social Service Entrepreneurs’ Experiences of Entrepreneur-Municipality Relationship
We investigate the complex dynamics between social service entrepreneurs and social
sector managers through the lens of network metaphor, utilizing our data on social
service entrepreneurs’ experiences of cooperation with municipalities. We examine
what kinds of dependencies exist in the entrepreneur–municipality relationships and
what kind of consequences these dependencies have on social service businesses run
by entrepreneurs. Basing on the social service entrepreneurs experience, our findings
suggest that while the cooperation with the municipality represents a prerequisite
for success, their business represent only one alternative for the renewal of social
service structures from the point of view of municipalities. In addition, the existence
of legally enforced supervisory duties incorporates a considerable amount of power
that influences areas of the entrepreneur–municipality relationships and interaction
other than just those defined by the supervisory and regulatory rights.W naszej pracy badamy złożoną dynamikę między przedsiębiorcami oferującymi usługi
społeczne a menadżerami sektora społecznego za pomocą metafory sieci, używając
danych dotyczących doświadczeń, jakie mają tacy przedsiębiorcy we współpracy z
władzami lokalnymi. Badamy jakiego rodzaju zależności istnieją w relacji przedsiębiorca
– władza lokalna oraz jakie konsekwencje zależności te mają na firmy prowadzące
działalność w sektorze usług społecznych. W oparciu o doświadczenia przedsiębiorców
z tego sektora, wyniki naszych badań sugerują, że o ile współpraca z władzami
lokalnymi jest warunkiem niezbędnym powodzenia działalności, ich przedsiębiorstwa
stanowią tylko jedną alternatywę dla odnowienia usług społecznych z punktu
widzenia władz lokalnych. Ponadto, istnienie narzuconych przez prawo obowiązków
nadzorowania zawiera w sobie znaczny ładunek władzy, która wpływa na relacje
między przedsiębiorcami a władzami lokalnymi oraz interakcje inne niż te zdefiniowane
prawami nadzoru i regulacjami
Superhard Phases of Simple Substances and Binary Compounds of the B-C-N-O System: from Diamond to the Latest Results (a Review)
The basic known and hypothetic one- and two-element phases of the B-C-N-O
system (both superhard phases having diamond and boron structures and
precursors to synthesize them) are described. The attention has been given to
the structure, basic mechanical properties, and methods to identify and
characterize the materials. For some phases that have been recently described
in the literature the synthesis conditions at high pressures and temperatures
are indicated.Comment: Review on superhard B-C-N-O phase
Ethylene-regulated gene expression in tomato fruit: characterization of novel ethylene-responsive and ripeningrelated genes isolated by differential display.
Differential display was used to isolate early ethyleneregulated genes from late immature green tomato fruit in order to obtain a broader understanding of the molecular basis by which ethylene coordinates the ripening process. Nineteen novel ethylene-responsive (ER) cDNA clones were isolated that fell into three classes: (i) ethylene up-regulated (ii) ethylene downregulated, and (iii) transiently induced. Expression analysis revealed that ethylene-dependent changes in mRNA accumulation occurred rapidly (15 min) for most of the ER clones. The predicted proteins encoded by the ER genes are putatively involved in processes as diverse as primary metabolism, hormone signalling and stress responses. Although a number of the isolated ER clones correspond to genes already documented in other species, their responsiveness to ethylene is described here for the ®rst time. Among the ER clones sharing high homology with regulatory genes, ER43, a putative GTP-binding protein, and ER50, a CTR1-like clone, are potentially involved in signal transduction. ER24 is homologous to the multiprotein bridging factor MBF1 involved in transcriptional activation, and ®nally, two clones are homologous to genes involved in post-transcriptional regulation: ER49, a putative translational elongation factor, and ER68, a mRNA helicase-like gene. Six ER clones correspond to as yet unidenti®ed genes. The expression studies indicated that all the ER genes are ripening-regulated, and, depending on the clone, show changes in transcript accumulation either at the breaker, turning, or red stage. Analysis of transcript accumulation in different organs indicated a strong bias towards expression in the fruit for many of the clones. The potential roles for some of the ER clone
Population genomics of post-glacial western Eurasia.
Western Eurasia witnessed several large-scale human migrations during the Holocene <sup>1-5</sup> . Here, to investigate the cross-continental effects of these migrations, we shotgun-sequenced 317 genomes-mainly from the Mesolithic and Neolithic periods-from across northern and western Eurasia. These were imputed alongside published data to obtain diploid genotypes from more than 1,600 ancient humans. Our analyses revealed a 'great divide' genomic boundary extending from the Black Sea to the Baltic. Mesolithic hunter-gatherers were highly genetically differentiated east and west of this zone, and the effect of the neolithization was equally disparate. Large-scale ancestry shifts occurred in the west as farming was introduced, including near-total replacement of hunter-gatherers in many areas, whereas no substantial ancestry shifts happened east of the zone during the same period. Similarly, relatedness decreased in the west from the Neolithic transition onwards, whereas, east of the Urals, relatedness remained high until around 4,000 BP, consistent with the persistence of localized groups of hunter-gatherers. The boundary dissolved when Yamnaya-related ancestry spread across western Eurasia around 5,000 BP, resulting in a second major turnover that reached most parts of Europe within a 1,000-year span. The genetic origin and fate of the Yamnaya have remained elusive, but we show that hunter-gatherers from the Middle Don region contributed ancestry to them. Yamnaya groups later admixed with individuals associated with the Globular Amphora culture before expanding into Europe. Similar turnovers occurred in western Siberia, where we report new genomic data from a 'Neolithic steppe' cline spanning the Siberian forest steppe to Lake Baikal. These prehistoric migrations had profound and lasting effects on the genetic diversity of Eurasian populations
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