REMOVED: Reverse Solute Diffusion and its Adverse Effect on Osmotic Power Production in Pressure Retarded Osmosis

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Catalyst-free synthesis of single crystalline ZnO nanonails with ultra-thin caps

Arrays of single-crystalline ZnO nanonails with tapering diameters and ultra-thin caps have been successfully synthesized on a silicon substrate via a simple catalyst-free thermal evaporation method. Each of the ZnO nanonails consists a nanowire (stem) on the bottom and an ultra-thin symmetrical hexagonal cap on the top. Structural characterization reveals that the synthesized ZnO nanonail has a wurtzite (WZ) structure with a preferred growth direction of [0001] in the stem and in the cap. Remarkably, the ultra-thin cap shows a diameter-to-thickness ratio of over 20:1, which is much higher in magnitude than those reported in previous works. Based on the systematic morphological characterization and structural analysis, a self-catalyzed vapor–liquid–solid (VLS) mechanism followed by a vapor–solid (VS) process is proposed to explain the growth of the nanonails. Optical properties are also investigated with Raman and photoluminescence (PL) techniques, which show good crystal quality of the synthesized nanonails

Cloning and molecular characterization of Triticum aestivum ornithine amino transferase (TaOAT) encoding genes

Background Ornithine aminotransferase (OAT, EC:2.6.1.13), alternatively known as ornithine delta aminotransferase (δOAT), is a pyridoxal phosphate (PLP)-dependent enzyme involved in the conversion of ornithine into glutamyl-5-semi-aldehyde (GSA) and vice versa. Up till now, there has been no study on OAT in wheat despite the success of its isolation from rice, maize, and sorghum. This study focuses on identification and molecular characterization of OAT in wheat. Results In total, three homeologous OAT genes in wheat genome were found on chromosome group 5, named as TaOAT-5AL, TaOAT-5BL, and TaOAT-5DL. Sequence alignment between gDNA and its corresponding cDNA obtained a total of ten exons and nine introns. A phylogenetic tree was constructed and results indicated that OATs shared highly conserved domains between monocots and eudicots, which was further illustrated by using WebLogo to generate a sequence logo. Further subcellular localization analysis indicated that they functioned in mitochondria. Protein-protein interactions supported their role in proline biosynthesis through interactions with genes, such as delta 1-pyrroline-5-carboxylate synthetase (P5CS) and pyrroline-5-carboxylate reductase (P5CR), involved in the proline metabolic pathway. Promoter analysis exposed the presence of several stress responsive elements, implying their involvement in stress regulation. Expression profiling illustrated that TaOAT was highly induced in the wheat plants exposed to drought or salt stress condition. Upregulated expression of TaOATs was observed in stamens and at the heading stage. A potential role of TaOAT genes during floret development was also revealed. Furthermore, the transgenic plants overexpressing TaOAT showed enhanced tolerance to drought stress by increasing proline accumulation. In addition, salt tolerance of the transgenic plants was also enhanced. Conclusion TaOATs genes were involved in proline synthesis and nitrogen remobilization because they interacted with genes related to proline biosynthesis enzymes and arginine catabolism. In addition, TaOAT genes had a role in abiotic stress tolerance and a potential role in floret development. The results of this study may propose future research in the improvement of wheat resistance to abiotic stresses

Dynamic carbon and sulfur cycling in the aftermath of the Lomagundi-Jatuli Event: Evidence from the Paleoproterozoic Hutuo Supergroup, North China Craton

The unprecedented positive δ13C excursion in carbonates deposited between 2.2 and 2.0 Ga, known as the Lomagundi-Jatuli Event (LJE), has been documented globally and linked to the rise of atmospheric oxygen. Increasing oxidation inevitably changed the atmosphere-hydrosphere system, but few chemostratigraphic or quantitative constraints for the aftermath of this event exists. Here, we describe a ~200 m-thick carbonate succession in the Huaiyincun Formation, Hutuo Supergroup, ~2.0–1.9 Ga, from the North China Craton. There is a lithological transition from pink-purple dolostones to grey dolostones at ca. 91.6 m above the base of the Huaiyincun Formation. The former are more enriched in hematite and detrital minerals, whereas the latter contain more organic matter but almost no detrital phases. Meanwhile, the frequent occurrence of tempesite structures, along with the abrupt decline of stromatolites in the upper Huaiyincun Formation, suggest a storm-dominated environment. These distinct features within the Huaiyincun Formation reveal increased water depth during a transgression event. Two types of Raman spectra of organic matter were found in the lower and upper Huaiyincun Formation, respectively, which is proposed to be the result of variable oxidation. At 65.6 m, 26 m below the lithological transition (~91.6 m), remarkable decreases in both δ13Ccarb and δ34SCAS are observed. This discordance between C-S isotopic excursions and sedimentological and mineralogical variations argues against a seawater depth gradient effect of the δ13Ccarb and δ34SCAS curves. Instead, the decline of δ13Ccarb rather correlates with the negative δ13Ccarb excursions in ca. 2.0 Ga carbonates from Gabon and Russia, known as the Shunga-Francevillian Event (SFE). The result of the quantitatively constrained paleo-seawater [SO42−]sw suggests a crash of the seawater sulfate reservoir compared with that during the preceding LJE. However, the decreased δ34SCAS and increased CAS concentration towards the top of the study unit represent the recovery of seawater sulfate reservoir. The coordinated decline in δ34SCAS and δ13Ccarb values is likely related to enhanced oxidation of continental pyrite and organic matter in the aftermath of the LJE. The Huaiyincun Formation therefore represents a critical interval that recorded dynamic carbon and sulfur cycles after the LJE

Photolithographic Approaches for Fabricating Highly Ordered Nanopatterned Arrays

In this work, we report that large area metal nanowire and polymer nanotube arrays were successfully patterned by photolithographic approach using anodic aluminum oxide (AAO) templates. Nanowires were produced by electrochemical deposition, and nanotubes by solution-wetting. The highly ordered patterns of nanowire and nanotube arrays were observed using scanning electron microscopy (SEM) and found to stand free on the substrate. The method is expected to play an important role in the application of microdevices in the future

Precipitation of high Mg-calcite and protodolomite using dead biomass of aerobic halophilic bacteria

The microbial dolomite model has been used to interpret the origin of sedimentary dolomite. In this model， the formation of low-temperature protodolomite， an important precursor to sedimentary dolomite， can be facilitated either by actively metabolizing cells of anaerobic microbes and aerobic halophilicarchaea or by their inactive biomass. Aerobic halophilic bacteria are widely distributed in （proto-）dolomite-depositing evaporitic environments and their biomass might serve as a template for the crystallization of protodolomite. To test this hypothesis， carbonation experiments were conducted using dead biomass of an aerobic halophilic bacterium （Exiguobacterium sp. strain JBHLT-3）. Our results show that dead biomass of JBHLT-3 can accelerate Mg2+ uptake in carbonate mineral precipitates. In addition， the amount of Mg incorporated into Ca-Mg carbonates is proportional to the concentration of biomass. High Mg-calcite is produced with 0.25 or 0.5 g/L biomass， whereasprotodolomite forms with 1 g/L biomass. This is confirmed by the main Raman peak of Ca-Mg carbonates， which shifts towards higher wavenumbers with increased Mg substitution. Microbial cells and their imprints are preserved on the surface of high Mg-calcite and protodolomite. Hence， this study furthers our understanding of the dolomitization within buried and dead microbial mats， which provides useful insights into the origin of ancient dolomite

Early Triassic oceanic red beds coupled with deep sea oxidation in South Tethys

Carbonate oceanic red beds (ORBs) are unusual in Phanerozoic shelf settings but can be widespread during discrete intervals. Several scenarios have been invoked to explain the origin of these ORBs but there remains uncertainty about the process by which the red pigmentation of ORBs forms. Here, we propose that the occurrence of ORBs at intermediate water depths in shelf regions is controlled by fluctuations in the redox state of deeper waters. We have examined Early Triassic Peri-Gondwana shelf sections in South Tibet which show the development of Spathian (late Early Triassic) ORBs at intermediate water depths. The red color of these ORBs is imparted by randomly dispersed hematite crystals that are microns in size, showing weak alteration by late burial diagenesis. Widespread anoxia, in both shelf seas and the oceanic realm, was well developed in the Early Triassic. Synchronous occurrence of Spathian ORBs in deep shelf regions is closely related to the improved oxidation in deeper settings, from anoxia to dysoxia, based on changes in the redox proxy of pyrite framboid sizes. It is, therefore, inferred that prolonged deep-water anoxia might serve as source of Fe (II) for the formation of ORBs when intensified upwelling develops. The global occurrence of Early Triassic ORBs is coincident with the significant rebound of biodiversity after the Permian-Triassic mass extinction, indicating the occurrence of ORBs marks the terminal stage of an oceanic anoxic event and ORBs can serve as an indicator of the ameliorated marine ecosystem