20,945 research outputs found
Corrigendum: Liu W-B, Wang C-Y, Tang Y-N, Wang Y, Pei W-X, Yan C-C (2024) Six new species of Cryptochironomus Kieffer (Diptera, Chironomidae) from the Nearctic region. ZooKeys 1200: 275–302. doi: 10.3897/zookeys.1200.119225
No full textCorrigendum: Liu W-B, Wang C-Y, Tang Y-N, Wang Y, Pei W-X, Yan C-C (2024) Six new species of Cryptochironomus Kieffer (Diptera, Chironomidae) from the Nearctic region. ZooKeys 1200: 275–302. https://doi.org/10.3897/ zookeys.1200.11922
Carbon cycling and POC turnover in the mesopelagic zone of the ocean: Insights from a simple model
No full textCarbon budgets of the mesopelagic zone are poorly constrained, highlighting our lack of understanding of the biota that inhabit this environment and their role in the cycling and sequestering of carbon in the deep ocean. A simple food web model of the mesopelagic zone is presented that traces the turnover of particulate organic carbon (POC), supplied as sinking detritus, through to its respiration by the biota via three pathways: colonization and solubilization of detritus by attached bacteria, production of free-living bacteria following losses of solubilization products during particle degradation, and consumption by detritivorous zooplankton. The relative consumption of detritus by attached bacteria was initially specified as 76%, with the remaining 24% by detritivores. Highlighting an asymmetry between consumption and respiration, the resulting predicted share of total respiration due to bacteria was 84.7%, with detritivores accounting for just 6.6% (with 6.5% and 2.2% by bacterivores and higher zooplankton, respectively). Bacteria thus dominated respiration and thereby acted as the principal sink for POC supplied to the mesopelagic zone, whereas zooplankton mainly recycled carbon back to the base of the food web as detritus or dissolved organic carbon rather than respiring it to CO2. Estimates of respiration are therefore not necessarily a reliable indicator of the relative roles of bacteria and zooplankton in consuming and processing POC in the mesopelagic zone of the ocean. The work highlighted a number of major unknowns, including how little we know in general about the dynamics and metabolic budgets of bacteria and zooplankton that inhabit the mesopelagic zone and, specifically, the degree to which the solubilized products of enzymatic hydrolysis of POC by attached bacteria are lost to the surrounding water, the magnitude and factors responsible for bacterial growth efficiency, the role of microbes in the nutrition of detritivores, and the recycling processes by which zooplankton return what they consume to the food web as detritus and dissolved organic matter
Ultrasensitive Room-Temperature Terahertz Direct Detection Based on a Bismuth Selenide Topological Insulator
No full textDespite their huge application capabilities, millimeter- and terahertz-wave photodetectors still face challenges in the detection scheme. Topological insulators (TIs) are predicted to be promising candidates for long-wavelength photodetection, due to the presence of Dirac fermions in their topologically protected surface states. However, photodetection based on TIs is usually hindered by the large dark current, originating from the mixing of bulk states with topological surface states (TSSs) in most realistic samples of TIs. Here millimeter and terahertz detectors based on a subwavelength metal–TI–metal (MTM) heterostructure are demonstrated. The achieved photoresponse stems from the asymmetric scattering of TSS, driven by the localized surface plasmon-induced terahertz field, which ultimately produces direct photocarriers beyond the interband limit. The device enables high responsivity in both the self-powered and bias modes even at room temperature. The achieved responsivity is over 75 A/W, with response time shorter than 60 ms in the self-powered mode. Remarkably, the responsivity increases by several orders of magnitude in the biased configuration, with the noise-equivalent power (NEP) of 3.6 × 10−13 W Hz−1/2 and a detectivity of 2.17 × 1011 cm Hz−1/2 W−1 at room temperature. The detection performances open a way toward realistic exploitation of TIs for large-area, real-time imaging within long-wavelength optoelectronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei
Surveying silk fibre degradation by crystallinity determination: a study on the Tang-Dynasty silk treasure from Famen Temple, China
No full textWhen Chinese archaeologists opened an unknown vault under the collapsed pagoda of Famen Temple near Xian (Shaanxi Province, NW China) in 1987, they found a vast amount of valuable silk textiles. The degraded textiles were part of a treasure comprising hundreds of artifacts deposited by Tang dynasty (ad 618–907) emperors as a gift to the temple. Run as a bilateral German-Chinese project, the Roemisch-Germanisches Zentralmuseum Mainz established a textile conservation laboratory in Shaanxi´s provincial capital Xian in 2001, joining numerous other laboratories that have existed there since the early 1990s.This preliminary study represents part of an ongoing investigation programme that accompanies the conservation work. The Tang dynasty silk is generally in a very poor state of preservation as a result of its long burial period. Large sections have only survived as an amorphous brown mass of fibre debris. Some parts are better preserved, however, offering the unique opportunity to study the whole range of degradation stages on ancient silks.This preliminary scientific investigation focuses on the determination of the silk fibres’ crystallinity and its relation to the ageing process. As we know from modern material, silk is mainly crystalline, albeit in a somewhat amorphous state. The methods of investigation used were X-ray diffraction (XRD) using synchrotron radiation, which is a new way to determine crystallinity of ancient silk fibres; and polarized Fourier transform infrared spectroscopy (FTIR) for the determination of crystallite orientation. Both methods were specifically devised to gain information on small single fibres
Review of Impedance-Reshaping-Based Power Sharing Strategies in Islanded AC Microgrids
No full textIn islanded AC microgrids, loads are supplied by parallel inverters-based distributed generation (DG) units. Accurate power sharing, which is always degraded by the mismatched line impedances of DG units, is an essential mission. Reshaping the output impedance of DG units is an effective method to improve power sharing performance via eliminating the impedance mismatch. This paper classifies and summarizes various impedance-reshaping-based power sharing strategies. Firstly, the comprehensive evaluation criteria of the power sharing methods are illustrated in terms of power sharing accuracy, unbalanced and harmonic power sharing, influence on voltage regulation, dependence on communication and feasibility in practical applications. According to the operating principles, the existing impedance reshaping methods are categorized into four groups: fixed virtual impedance, adaptive virtual impedance regulation, impedance droops, and reconfiguration of inner loops. Then the advantages and dis..
Direct laser writing of poly(phenylene vinylene) on poly(barrelene)
No full textThe ring-opening metathesis polymerization of barrelene (bicyclo[2.2.2]octa-2,5,7-triene) is described. The monomer was synthesized using an optimized route and characterized, for the first time, using X-ray diffraction analysis of a coordination complex. The solubility of poly(barrelene) was found to correlate with the ratio of cis to trans exocyclic vinylenes in the polymer backbone. Copolymers of barrelene and norbornene were also prepared and used to obtain robust films. The barrelene-containing polymers underwent spontaneous dehydrogenation under air or upon being subjected to laser pulses to afford poly(phenylene vinylene). A series of well-defined patterns with micrometer dimensions were created by direct laser writing on films of poly(barrelene-co-norbornene) and visualized by the fluorescence of the conjugated polymer that formed upon irradiation
Chemotherapeutic risk incRNA-PVT1 SNP sensitizes metastatic colorectal cancer to FOLFOX regimen
No full textRecent studies have identified that long noncoding RNA (lncRNA) might affect the responses to anticancer drug treatment, including colorectal cancer (CRC). However, the association between single-nucleotide polymorphisms (SNPs) in PVT1 and the chemotherapy response in metastatic colorectal cancer has yet to be clarified. In this study, the PVT1 rs2278176 CT/TT genotypes were found to be associated with an increased overall survival (OS) and progression-free survival (PFS) compared with the CC genotype. Furthermore, patients harboring the rs2278176 CT/TT genotypes had a greater chance of achieving clinical benefit from 5-Fluorouracil/leucovorin combined with oxaliplatin (FOLFOX). In vivo nude mice experiments demonstrated that the CRISPR/ Cas9 mediated rs2278176 C to T mutation significantly inhibited the tumorigenesis of colorectal cancer cells treated with 5-Fu, but not control DMSO treated cells. Furthermore, the apoptotic rate was significantly enhanced by treatment with 5-Fu in the CRC cells carrying with the CT/TT genotypes. Functional studies demonstrated that the PVT1 rs2278176 C to T mutation altered the binding site for hsa-miR-297, and that hsa-miR-297 downregulated Glutathione S-Transferase Alpha 2(GSTA2), a member of phase II detoxification enzyme, in an Argonaute 2(Ago2)-dependent manner. Moreover, GSTA2 levels were downregulated in the cancer tissues of patients carrying rs2278176 CT/TT genotypes. High GSTA2 expression predicted poor clinical outcome in metastatic colorectal cancer treated with FOLFOX. In conclusion, this study provided that PVT1 with rs2278176 T allele altered the binding affinity with hsa-miR-297, leading to decreased GSTA2 expression and sensitized CRC cells to FOLFOX chemotherapy, suggesting
DefusionNet: Defocus blur detection via recurrently fusing and refining discriminative multi-scale deep features
No full textAlbeit great success has been achieved in image defocus blur detection, there are still several unsolved challenges, e.g., interference of background clutter, scale sensitivity and missing boundary details of blur regions. To deal with these issues, we propose a deep neural network which recurrently fuses and refines multi-scale deep features (DeFusionNet) for defocus blur detection. We first fuse the features from different layers of FCN as shallow features and semantic features, respectively. Then, the fused shallow features are propagated to deep layers for refining the details of detected defocus blur regions, and the fused semantic features are propagated to shallow layers to assist in better locating blur regions. The fusion and refinement are carried out recurrently. In order to narrow the gap between low-level and high-level features, we embed a feature adaptation module before feature propagating to exploit the complementary information as well as reduce the contradictory response of different feature layers. Since different feature channels are with different extents of discrimination for detecting blur regions, we design a channel attention module to select discriminative features for feature refinement. Finally, the output of each layer at last recurrent step are fused to obtain the final result. We collect a new dataset consists of various challenging images and their pixel-wise annotations for promoting further study. Extensive experiments on two commonly used datasets and our newly collected one are conducted to demonstrate both the efficacy and efficiency of DeFusionNet
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