Whole-rock geochemistry and zircon trace element, UPb and Hf isotopic data for Upper Permian volcanic ash at Shangsi show a significant change in source from the Emeishan Large Igneous Province (LIP) ...to a convergent plate margin magmatic arc. The lower stratigraphic samples display high Al2O3/TiO2 ratios, strong negative Eu anomalies, and no depletion in high field strength elements. Zircons with ages of ca. 260 Ma from these ashes have a geochemical affinity to within-plate-type magmas and with felsic ignimbrites from the uppermost part of the Emeishan volcanic succession at Binchuan. These features, combined with relatively high εHf(t) values and low Th/Nb ratios in the zircons, imply a late-stage felsic volcanic origin related to Emeishan LIP. The upper stratigraphic samples at Shangsi display significant depletion in Nb and Ti; zircons separated from these volcanic ashes are chemically similar to those from arc-related/orogenic rocks, indicative of a magmatic arc source. Combined with published high-precision CA-TIMS data for these volcanic ash layers, the Emeishan volcanism can be constrained to between ca. 260–257.8 Ma. The age of Emeishan volcanism is consistent with the Wuchiapingian climate cooling event, supporting a potential linkage between these two phenomena.
•Upper Permian volcanic ash layers display a significant change in source•Emeishan volcanism continued until ca. 257.8 Ma•Emeishan LIP is consistent with the early Wuchiapingian cooling.
The three-host tick Haemaphysalis longicornis is an obligate blood-sucking ectoparasite. In life-stage transitions, microRNAs (miRNAs) show a variety of expression changes. To investigate these ...changes, deep sequencing technology was applied to identify the conserved and potentially novel miRNAs expressed during the different life stages of H. longicornis. Total RNA from eggs, unfed larvae, unfed nymphs and unfed adults was extracted for deep sequence analysis. Deep sequencing on a Hiseq 4000 generated a total of 111,192,069 reads, grouped into four small RNA (sRNA) libraries, one for each of the four developmental stages of H. longicornis. Among these sequences, 78 conserved and 55 potentially novel miRNAs were identified, including stage-specific and differentially expressed miRNAs. Gene ontology (GO) analysis indicated significantly enriched GO terms related to cell proliferation and differentiation, including specific terms for the processes of development, growth, metabolism, regulation of biological functions, reproduction, and membrane enzyme regular activity. Kyoto Encyclopedia of Gene and Genomes (KEGG) analysis revealed a significant enrichment of the insulin, notch, Hippo, and Wnt signaling pathways for growth and development. Our data highlight the abundance of miRNA changes (conserved and potentially novel) in the different life stages of H. longicornis. In particular, stage-specific miRNAs, as observed, are essential regulators for the development of H. longicornis.
First-principles calculations have been performed to study the chemically doped platinum diselenide (PtSe
2) monolayers. We examine the stability of different doping sites by calculating the ...formation energy. The different electronic and magnetic characters originate from hybridization between the dopants and nearest local atoms. Exceptional electronic and magnetic characters are observed in the B-, P-, Li-, and Ca-doped cases because of doping site independence. The magnetic behavior of the dopant atoms is found to be complex because of interplay between strong structural relaxation, spin lattice coupling, and crystal field splitting. More interestingly, the ferromagnetic half metallic character obtained in B- and N-doped cases, expected to be very useful because of large half metallic energy bandgap. The interaction between dopants is analyzed as a function of their separation, showing that substitution typically counteracts spin polarization. The long range ferromagnetic behavior can be established with improved stability which suggest the high magnetic transition temperatures, found for the B-, F-, N-, P-, and Li-doped at Pt sites which make them potential candidate for applications in electronic devices as well as in spintronics.
In order to reduce the deformation and assembly error in an antenna thin wall parts assembly process, the assembly location or clamping positions need to be optimized. In this paper, the effect of ...clamping positions and clamping force on the thin wall parts deformation is analyzed considering the gravity by finite element simulation under different clamping force. The clamping positions are optimized with the Adaptive Simulated Annealing (ASA), Multi-Island Genetic Algorithm (MIGA) and Particle Swarm Optimization (PSO) algorithm by Isight software to reduce the deformation. Comparing with MIGA and PSO method, the results show that the clamping position optimization based on ASA exhibits the better results and superior than the MIGA and PSO no matter whether it has the effect of gravity. Simultaneously, through establishing the contact force model and contact deformation model, the nonlinear relationship between contact force, contact deformation and contact area is qualitatively analyzed, and the node deformation is calculated by theoretical formula. Comparing with those results, it is shown that the theoretical value matches well with the simulation results. Finally, some clamping scheme principles are proposed so that it provides a basis for reducing the deformation and assembly error of thin wall parts in future.
In order to achieve the stringent accuracy requirement of some robotic applications such as robotic measurement systems, it is critical to compensate for nongeometric errors such as compliance errors ...and thermal errors in addition to geometric errors. This paper investigates the effect of geometric errors, link compliance and temperature variation on robot positioning accuracy. A comprehensive error model is derived for combining geometric errors, position–dependent compliance errors and time–variant thermal errors. A general methodology is developed to identify these errors simultaneously. A laser tracker is applied to calibrate these errors by an inverse calibration method. Robot geometric errors and compliance errors are calibrated at room temperature while robot parameter thermal errors are calibrated at different temperatures when the robot warms up and cools down. Empirical thermal error models are established using orthogonal regression methods to correlate robot parameter thermal errors with the corresponding temperature field. These models can be built into the controller and used to compensate for quasi-static thermal errors due to internal and external heat sources. Experimental results show that the robot accuracy is improved by an order of magnitude after calibration.
Coronary artery bypass graft failure represents an unsolved problem in interventional cardiology and heart surgery. Late occlusion of autologous saphenous vein bypass grafts is a consequence of ...neointima formation underpinned by smooth muscle cell (SMC) migration and proliferation. Poor long term patency and the lack of pharmacologic agents that prevent graft failure necessitate effective alternative therapies. Our objective here was to evaluate the effect of targeted inhibition of the bZIP transcription factor c-Jun on intimal hyperplasia in human saphenous veins and vein graft stenosis after autologous end-to-side transplantation. DNAzymes targeting c-Jun attenuated intimal hyperplasia in human saphenous vein explants. Adenovirus-forced c-Jun expression stimulated SMC proliferation, proliferating cell nuclear antigen, and MMP-2 expression. c-Jun DNAzymes abrogated Adeno-c-Jun-inducible SMC growth and wound repair and reduced intimal thickening in jugular veins of New Zealand white rabbits 4 weeks after autologous end-to-side transplantation to carotid arteries. Conversely, in a DNAzyme-free setting, Adeno-c-Jun potentiated neointima formation in the veins compared with Adeno-LacZ. Inducible c-Jun expression is ERK1/2- and JNK-dependent but p38-independent. Injury- and shear-inducible c-Jun controls early growth response-1. These data demonstrate that strategies targeting c-Jun may be useful for the prevention of vein graft stenosis. Control of one important shear-responsive transcription factor by another indicates the existence of transcriptional amplification mechanisms that magnify the vascular response to cell injury or stress through inducible transcriptional networks.
APYRASEs, which directly regulate intra- and extra-cellular ATP homeostasis, play a pivotal role in the regulation of various stress adaptations in mammals, bacteria and plants. In the present study, ...we identified and characterized wheat APYRASE family members at the genomic level in wheat. The results identified a total of nine APY homologs with conserved ACR domains. The sequence alignments, phylogenetic relations and conserved motifs of wheat APYs were bioinformatically analyzed. Although they share highly conserved secondary and tertiary structures, the wheat APYs could be mainly categorized into three groups, according to phylogenetic and structural analysis. Additionally, these APYs exhibited similar expression patterns in the root and shoot, among which TaAPY3-1, TaAPY3-3 and TaAPY3-4 had the highest expression levels. The time-course expression patterns of the eight APYs in response to biotic and abiotic stress in the wheat seedlings were also investigated. TaAPY3-2, TaAPY3-3, TaAPY3-4 and TaAPY6 exhibited strong sensitivity to all kinds of stresses in the leaves. Some APYs showed specific expression responses, such as TaAPY6 to heavy metal stress, and TaAPY7 to heat and salt stress. These results suggest that the stress-inducible APYs could have potential roles in the regulation of environmental stress adaptations. Moreover, the catalytic activity of TaAPY3-1 was further analyzed in the in vitro system. The results showed that TaAPY3-1 protein exhibited high catalytic activity in the degradation of ATP and ADP, but with low activity in degradation of TTP and GTP. It also has an extensive range of temperature adaptability, but preferred relatively acidic pH conditions. In this study, the genome-wide identification and characterization of APYs in wheat were suggested to be useful for further genetic modifications in the generation of high-stress-tolerant wheat cultivars.
Tenuigenin (TEN), a natural product from the Chinese herb Polygala tenuifolia root, has been reported to improve cognitive function and exhibits neuroprotective effects in pharmacological studies of ...the central nervous system. Synaptic transmission is the essential process of brain physiological functions such as learning and memory formation, and TEN has been shown to facilitate the basic synaptic transmission.
Although our previous work has demonstrated that TEN is able to potentiate the basic synaptic transmission, the potential mechanism remains unclear. Here we investigated the effect of TEN on the synaptic transmission and analysed the potential mechanism. We hope that these findings will contribute to explain the role of TEN as a nootropic product or neuroprotective drug in the future.
Field excitatory postsynaptic potentials (fEPSPs), spontaneous excitatory postsynaptic currents (sEPSCs) and miniature spontaneous excitatory postsynaptic currents (mEPSCs) were recorded, by using in vitro field potential electrophysiology and whole-cell patch clamp techniques in acute hippocampal slices from rats.
TEN perfusion significantly enhanced the slope of fEPSPs and reduced the ratio of paired-pulse facilitation. Moreover, TEN increased the frequency and amplitude of sEPSCs but only improved the frequency of mEPSCs rather than amplitude in hippocampal CA1 pyramidal neurons. With removal of extracellular calcium, TEN treatment also enhanced the mEPSCs frequency without affecting amplitude. Interestingly, the increase of mEPSCs frequency caused by TEN was blocked by chelation of intracellular calcium with BAPTA-AM.
These results indicate that TEN enhances the basic synaptic transmission via stimulating presynaptic intracellular calcium.
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The warm hydroforming process has become an emerging technology in recent years to reduce the weight of automotive body structure and minimize the number of process steps. In this study, analytical ...models were developed to investigate the effects of process conditions such as temperature, hydraulic pressure, blank holder force and forming speed. The analytical model under hydro-mechanical deep drawing (HMD) condition was developed based on experimental results in the literatures. FE models were also developed to validate the analytic models. Then, the analytic model was validated through comparisons with both existing experimental results and FE results. The analytical model provided rapid and reasonably accurate results for the design of warm hydroforming process. Based on this analytic model, several parametric studies were performed regarding to the temperature, hydraulic pressure, blank holder force, and punch speed conditions. It was demonstrated that the process windows for a successful part forming could be rapidly predicted with a reasonable accuracy by the analytic model compared to lengthy and costly thermo-mechanical FEA or experimental trial and error.
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