In order to reveal a steady distribution structure of point defects of no growing Si on the solid-liquid interface, the crystals were grown at a high pulling rate, which Vs becomes predominant, and ...the pulling was suddenly stopped. After restoring the variations of the crystal by the pulling-stop, the crystals were then left in prolonged contact with the melt. Finally, the crystals were detached and rapidly cooled to freeze point defects and then a distribution of the point defects of the as-grown crystals was observed. As a result, a dislocation loop (DL) region, which is formed by the aggregation of interstitials (Is), was formed over the solid-liquid interface and was surrounded with a Vs-and-Is-free recombination region (Rc-region), although the entire crystals had been Vs rich in the beginning. It was also revealed that the crystal on the solid-liquid interface after the prolonged contact with the melt can partially have a Rc-region to be directly in contact with the melt, unlike a defect distribution of a solid-liquid interface that has been growing. This experimental result contradicts a hypothesis of Voronkov's diffusion model, which always assumes the equilibrium concentrations of Vs and Is as the boundary condition for distribution of point defects on the growth interface. The results were disscussed from a qualitative point of view of temperature distribution and thermal stress by the pulling-stop.
•Growth interface of CZ crystal can have recombination region to be directly contact with Si melt.•Recombination region is always formed at boundary between dislocation loop and vacancy region.•Interstitials are generated at region near growth interface where thermal stress is increased.
REBa 2 Cu 3 O 7-δ (RE: rare earth/Y) coated conductors have good critical current characteristics under high magnetic fields. Their application to superconducting magnets generating above 25T is ...under active study. However, performance inhomogeneity along their length may cause damaging hotspots. Adapted winding technologies are needed to mitigate this phenomenon. One of such winding techniques is the two-tape bundle co-winding method, where two REBCO tapes are co-wound along with an isolating tape to form the conductor. To test this solution, a double pancake coil was wound with one of the pancakes having an artificially degraded short section on one of the tapes, where the critical current is close to 0. The I-V characteristics of both damages and undamaged pancakes are compared and analyzed based on critical current density J c ( T,B ,θ) data, in terms of operation margins. At low voltage levels, similar I-V characteristics for damaged and undamaged pancakes are observed. The behavior is found similar to the expected behavior of a coil whose critical current I c is locally reduced by 50%, demonstrating the effectiveness of two-tape bundle for current redistribution in case of local defect, even under high current density.
Water loss through leaking pipes constitutes a major challenge to the operational service of water utilities. In recent years, increasing concern about the financial loss and environmental pollution ...caused by leaking pipes has been driving the development of efficient algorithms for detecting leakage in water piping networks. Water distribution networks (WDNs) are disperse in nature with numerous number of nodes and branches. Consequently, identifying the segment(s) of the network and the exact leaking pipelines connected to this segment(s) where higher background leakage outflow occurs is a challenging task. Background leakage concerns the outflow from small cracks or deteriorated joints. In addition, because they are diffuse flow, they are not characterised by quick pressure drop and are not detectable by measuring instruments. Consequently, they go unreported for a long period of time posing a threat to water loss volume. Most of the existing research focuses on the detection and localisation of burst type leakages which are characterised by a sudden pressure drop. In this work, an algorithm for detecting and estimating background leakage in water distribution networks is presented. The algorithm integrates a leakage model into a classical WDN hydraulic model for solving the network leakage flows. The applicability of the developed algorithm is demonstrated on two different water networks. The results of the tested networks are discussed and the solutions obtained show the benefits of the proposed algorithm. A noteworthy evidence is that the algorithm permits the detection of critical segments or pipes of the network experiencing higher leakage outflow and indicates the probable pipes of the network where pressure control can be performed. However, the possible position of pressure control elements along such critical pipes will be addressed in future work.
Abstract Blood flow restriction (BFR) alone or in combination with exercise has been shown to result in favorable effects on skeletal muscle form and function. The pressure applied should be high ...enough to occlude venous return from the muscle but low enough to maintain arterial inflow into the muscle. The optimal pressure for beneficial effects on skeletal muscle are currently unknown; however, preliminary data from our laboratory suggests that there may be a point where greater pressure may not augment the response (e.g. metabolic accumulation, cell swelling) but may actually result in decrements (e.g. muscle activation). This led us to wonder if BFR elicits somewhat of a hormesis effect. The purpose of this manuscript is to discuss whether pressure may be modulated to maximize skeletal muscle adaptation with resistance training in combination with BFR. Furthermore, the potential safety issues that could arise from increasing pressure too high are also briefly reviewed. We hypothesize that with BFR there is likely a moderate (∼50% estimated arterial occlusion pressure) pressure that maximizes the anabolic response to skeletal muscle without producing the potential negative consequences of higher pressures. Thus, BFR may follow the hormesis theory to some degree, in that a low/moderate dose of BFR produces beneficial effects while higher pressures (at or near arterial occlusion) may decrease the benefits of exercise and increase the health risk. This hypothesis requires long term studies investigating chronic training adaptations to differential pressures. In addition, how differences in load interact with differences in pressure should also be investigated.
Histone acetylation is controlled by HATs and HDACs, which are essential epigenetic elements that regulate plant response to environmental stresses. A previous study revealed that a deficiency in an ...HDAC isoform (HDA19) increases tolerance to high salinity stress in the Arabidopsis wild-type Col-0 background. Here, the increased tolerance of hda19 to drought and heat stresses is demonstrated. Results indicate that hda19 plants have greater tolerance than wild-type plants to stress conditions. The data indicate that the stress response pathway coordinated by HDA19 plays a pivotal role in increasing tolerance to a variety of different abiotic stresses in Arabidopsis, including salinity, drought, and heat. The greater level of tolerance of hda19 plants to several different environmental stresses suggests that HDA19 represents a promising target for pharmacological manipulation in order to enhance abiotic stress tolerance in plants.
Abbreviations: HAT, histone acetyltransferase; HDAC, histone deacetylase; HSF, heat shock transcription factor; RPD3, reduced potassium dependency 3; SIRT, Silent Information Regulator 2
Introducing hydrophilic groups into carboxylates is a way to modify semiclathrate hydrate frameworks and change the properties of the hydrates. In this study, we report the characterization of ...semiclathrate hydrates formed by tetra-
n
-butylammonium (TBA) 2-hydroxybutyrate (2HB). In addition, TBA lactate and the TBA 2HB salt formed stable hydrate crystals, which basically had rectangular columnar shapes. We performed equilibrium measurements and calorimetry. The melting temperature and fusion heat of the TBA 2HB hydrate crystals were 285.3 K and 177 kJ kg
−1
, respectively. A comparison with other carboxylate anions showed that the substitution of hydrogen atom at the 2-position in the carbon chain by a hydrophilic hydroxy group stabilizes the hydrates more than that by hydrophobic methyl group, which is the case for alcohols in clathrate hydrates. The phase equilibrium data for a number of semiclathrate hydrates were compared. A rough trend of temperature depending on type of guest anions was observed, but it is unclear if there are other correlating factors.
Introducing hydrophilic groups into carboxylates is a way to modify semiclathrate hydrate frameworks and change the properties of the hydrates.
Toxin-antitoxin (TA) systems are parasitic genetic elements found in almost all bacterial genomes. They are exchanged horizontally between cells and are typically poorly conserved across closely ...related strains and species. Here, we report the characterization of a tripartite TA system in the bacterial pathogen
that is highly conserved across
species genomes. This system (denoted HipBST
) is a distant homolog of the recently discovered split-HipA system in
(HipBST
). We present bioinformatic, molecular, and structural analyses of the divergence between these two systems and the functionality of this newly described TA system family. Furthermore, we provide evidence to refute previous claims that the toxin in this system (HipT
) possesses bifunctionality as an
virulence protein. Overall, this work expands our understanding of the split-HipA system architecture and illustrates the potential for undiscovered biology in these abundant genetic elements.
Recent awareness that most microorganisms in the environment are resistant to cultivation has prompted scientists to directly clone useful genes from environmental metagenomes. Two screening methods ...are currently available for the metagenome approach, namely, nucleotide sequence-based screening and enzyme activity-based screening. Here we have introduced and optimized a third option for the isolation of novel catabolic operons, that is, substrate-induced gene expression screening (SIGEX). This method is based on the knowledge that catabolic-gene expression is generally induced by relevant substrates and, in many cases, controlled by regulatory elements situated proximate to catabolic genes. For SIGEX to be high throughput, we constructed an operon-trap gfp-expression vector available for shotgun cloning that allows for the selection of positive clones in liquid cultures by fluorescence-activated cell sorting. The utility of SIGEX was demonstrated by the cloning of aromatic hydrocarbon-induced genes from a groundwater metagenome library and subsequent genome-informatics analysis.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We report in situ measurements of plasma irregularities associated with a reverse flow event (RFE) in the cusp F region ionosphere. The Investigation of Cusp Irregularities 3 (ICI‐3) sounding rocket, ...while flying through a RFE, encountered several regions with density irregularities down to meter scales. We address in detail the region with the most intense small‐scale fluctuations in both the density and in the AC electric field, which were observed on the equatorward edge of a flow shear, and coincided with a double‐humped jet of fast flow. Due to its long‐wavelength and low‐frequency character, the Kelvin‐Helmholtz instability (KHI) alone cannot be the source of the observed irregularities. Using ICI‐3 data as inputs, we perform a numerical stability analysis of the inhomogeneous energy‐density‐driven instability (IEDDI) and demonstrate that it can excite electrostatic ion cyclotron waves in a wide range of wave numbers and frequencies for the electric field configuration observed in that region, which can give rise to the observed small‐scale turbulence. The IEDDI can seed as a secondary process on steepened vortices created by a primary KHI. Such an interplay between macroprocesses and microprocesses could be an important mechanism for ion heating in relation to RFEs.
Key Points
Sounding rocket in situ observation of small‐scale irregularities associated with a flow shear and a double‐humped jet of fast plasma flow
The inhomogeneous energy‐density‐driven instability (IEDDI) is a plausible mechanism for the creation of the small‐scale plasma structures
The IEDDI acts as a secondary process on a primary instability in regions of strongly sheared flows
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