Rigid molecular sieving materials are the ideal candidates for gas separation (e. g., C2H2/C2H4) due to their ultrahigh adsorption selectivity and the absence of gas co‐adsorption. However, the ...absolute molecular sieving effect for C2H2/C2H4 separation has rarely been realized because of their similar physicochemical properties. Herein, we demonstrate the absolute molecular sieving of C2H2 from C2H4 by a rigid ultra‐microporous metal‐organic framework (F−PYMO−Cu) with 1D regular channels (pore size of ca. 3.4 Å). F−PYMO−Cu exhibited moderate acetylene uptake (35.5 cm3/cm3), but very low ethylene uptake (0.55 cm3/cm3) at 298 K and 1 bar, yielding the second highest C2H2/C2H4 uptake ratio of 63.6 up to now. One‐step C2H4 production from a binary mixture of C2H2/C2H4 and a ternary mixture of C2H2/CO2/C2H4 at 298 K was achieved and verified by dynamic breakthrough experiments. Coupled with excellent thermal and water stability, F−PYMO−Cu could be a promising candidate for industrial C2 separation tasks.
Double (bond) take: The molecular sieving of C2H2 from C2H4 has been realized in a rigid ultra‐microporous metal organic framework that enabled efficient one‐step C2H4 production from the binary gas mixture C2H2/C2H4 and the ternary gas mixture C2H2/CO2/C2H4.
The effect of climate change on tropical cyclone intensity has been an important scientific issue for a few decades. Although theory and modeling suggest the intensification of tropical cyclones in a ...warming climate, there are uncertainties in the assessed and projected responses of tropical cyclone intensity to climate change. While a few comprehensive reviews have already provided an assessment of the effect of climate change on tropical cyclone activity including tropical cyclone intensity, this review focuses mainly on the understanding of the effect of climate change on basin-wide tropical cyclone intensity, including indices for basin-wide tropical cyclone intensity, historical datasets used for intensity trend detection, environmental control of tropical cyclone intensity, detection and simulation of tropical cyclone intensity change, and some issues on the assessment of the effect of climate change on tropical cyclone intensity. In addition to the uncertainty in the historical datasets, intertwined natural variabilities, the considerable model bias in the projected large-scale environment, and poorly simulated inner-core structures of tropical cyclones, it is suggested that factors controlling the basin-wide intensity can be different from individual tropical cyclones since the assessment of the effect of climate change treats tropical cyclones in a basin as a whole.
Current knowledge of RNA virus biodiversity is both biased and fragmentary, reflecting a focus on culturable or disease-causing agents. Here we profile the transcriptomes of over 220 invertebrate ...species sampled across nine animal phyla and report the discovery of 1,445 RNA viruses, including some that are sufficiently divergent to comprise new families. The identified viruses fill major gaps in the RNA virus phylogeny and reveal an evolutionary history that is characterized by both host switching and co-divergence. The invertebrate virome also reveals remarkable genomic flexibility that includes frequent recombination, lateral gene transfer among viruses and hosts, gene gain and loss, and complex genomic rearrangements. Together, these data present a view of the RNA virosphere that is more phylogenetically and genomically diverse than that depicted in current classification schemes and provide a more solid foundation for studies in virus ecology and evolution.
In order to realize roof control of shallow coal seam group mining in Western China, combining with engineering statistics, physical simulation and theoretical analysis, the roof weighting ...characteristics during lower coal seam mining were revealed, and the classification of shallow coal seam group was proposed. Based on this, mechanical models of roof structure were set up, and the calculation method of support resistance was determined. The results show that the roof weighting is closely related to the interburden thickness and the mining height of lower coal seam, considering the ratio of interburden thickness to the mining height, as well as the key stratum structure, the classification of shallow coal seam group was put forward. The first type is shallow coal seam group with no key stratum (SCSG-No), its roof pressure is mainly affected by caving roof of upper coal seam, and the interburden roof forms slanting pillar-beam structure. The second type is shallow coal seam group with single key stratum (SCSG-S), interburden roof represents step voussoir beam structure. The third type is shallow coal seam group with double key strata (SCSG-D), interburden roof can form double key strata structure, the lower key stratum forms slanting step voussoir beam structure, while the upper key stratum forms voussoir beam structure, besides, longwall face represents large-small periodic weighting. Through establishing the roof structure models, the calculation formulas of support resistance were determined, it can provide basis for roof control and promote safe mining in Western China.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To better understand what determines the Last Glacial Maximum (LGM) cold and dry climate, a suite of numerical experiments with the Nanjing University of Information Science and Technology Earth ...System Model version 1 are conducted to assess the relative contributions of individual external forcings, including greenhouse gases (GHGs), ice sheets (IS), land-sea configuration (LSC) and the Earth’s orbital parameters, and the contribution of their combination in the LGM mean climate change. Results of the single-forcing sensitivity experiments not only reveal spatial patterns of temperature and precipitation changes that are different from today’s climate, but also shed light on understanding the underlying processes through which each forcing contributes to the formation of the LGM climate. The full forcing experiment simulates a 5.3 K global cooling and an 11.8% reduction of the global mean precipitation, thus yielding a hydrological sensitivity of 2.2% K
−1
, which is larger than that caused by the present-day GHG forcing. The excessive hydrological sensitivity is primarily attributed to the land-sea configuration change, since its dynamic factor (circulation change) amplifies the precipitation reduction at the tropical convergence zones over both hemispheres. The GHG forcing is the largest contributor to the tropical cooling, whereas ice sheets are responsible for the large hemispheric temperature asymmetry and meridional gradients of the zonal mean temperature change during the LGM period. The LGM precipitation is characterized by decreased precipitation over the Indo-Pacific Ocean and a salient wave train pattern over the Northern Hemisphere (NH). The GHG and LSC forcings are the major contributors to the former since they can change the Indo-Pacific sea surface temperature and the associated Walker circulation, while ice sheets lead to the wave train pattern over the NH by changing the North Atlantic jet stream/storminess and shifting the Intertropical Convergence Zone southward. The climate responses to the LGM forcings are nonlinear. The nonlinearity mainly comes from the overlapping effects induced by the IS and LSC forcings.
Single point incremental forming (SPIF) is a sheet metal forming technique which has gained considerable interest in the research community due to its enhanced formability, greater process ...flexibility and reduced forming forces. However, a significant impediment in the industrial adoption of this process is the accurate prediction of fracture during the forming process. This work uses a recently developed fracture model combined with finite element analyses to predict the occurrence of fracture in SPIF of two shapes, a cone and a funnel. Experiments are performed to validate predictions from FEA in terms of forming forces, thinning and fracture depths. In addition to showing excellent predictions, the primary deformation mechanism in SPIF is compared to that in conventional forming process with a larger geometry-specific punch, using the deformation history obtained from FEA. It is found that both through-the-thickness shear and local bending of the sheet around the tool play a role in fracture in the SPIF process. Additionally, it is shown that in-spite of higher shear in SPIF, which should have a retarding effect on damage accumulation, high local bending of the sheet around the SPIF tool causes greater damage accumulation in SPIF than in conventional forming. Analysis of material instability shows that the higher rate of damage causes earlier growth of material instability in SPIF. A new theory, named the ‘noodle’ theory, is proposed to show that the local nature of deformation is primarily responsible for increased formability observed in SPIF, in-spite of greater damage accumulation as compared to conventional forming.
Deep convection in polar oceans plays a critical role in the variability of global climate. In this study, we investigate potential impacts of atmosphere–sea ice–ocean interaction on deep convection ...in the Southern Ocean (SO) of a climate system model (CSM) by changing sea ice–ocean stress. Sea ice–ocean stress plays a vital role in the horizontal momentum exchange between sea ice and the ocean, and can be parameterized as a function of the turning angle between sea ice and ocean velocity. Observations have shown that the turning angle is closely linked to the sea-ice intrinsic properties, including speed and roughness, and it varies spatially. However, a fixed turning angle, i.e., zero turning angle, is prescribed in most of the state-of-the-art CSMs. Thus, sensitivities of SO deep convection to zero and non-zero turning angles are discussed in this study. We show that the use of a non-zero turning angle weakens open–ocean deep convection and intensifies continental shelf slope convection. Our analyses reveal that a non-zero turning angle first induces offshore movement of sea ice transporting to the open SO, which leads to sea ice decrease in the SO coastal region and increase in the open SO. In the SO coastal region, the enhanced sea-ice divergence intensifies the formation of denser surface water descending along continental shelf by enhanced salt flux and reduced freshwater flux, combined with enhanced Ekman pumping and weakened stratification, contributing to the occurrence and intensification of continental shelf slope convection. On the other hand, the increased sea ice in the open SO weakens the westerlies, enhances sea-level pressure, and increases freshwater flux, whilst oceanic cyclonic circulation slows down, sea surface temperature and sea surface salinity decrease in the open SO response to the atmospheric changes. Thus, weakened cyclonic circulation, along with enhanced freshwater flux, reduced deep–ocean heat content, and increased stability of sea water, dampens the open–ocean deep convection in the SO, which in turn cools the sea surface temperature, increases sea-level pressure, and finally increases sea-ice concentration, providing a positive feedback. In the CSM, the use of a non-zero turning angle has the capability to reduce the SO warm bias. These results highlight the importance of an accurate representation of sea ice–ocean coupling processes in a CSM.
To realize high-performance and long life span supercapacitors, highly electrochemically active materials and rational design of structure are highly desirable. Herein, a hierarchical ...NiCo-LDH/NiCoP@NiMn-LDH hybrid electrode (NCLP@NiMn-LDH) was synthesized on carbon cloth via a hydrothermal reaction and phosphorization treatment. Owing to the introduction of NiCoP and design of the core–shell structure, the hybrid electrode showed significantly improved electrochemical performance. The as-fabricated hybrid electrode exhibited a high specific capacitance of 2318 F g −1 at 1 A g −1 , with a superior cyclic stability. Additionally, an asymmetric supercapacitor (NCLP@NiMn-LDH//AC) was assembled with a voltage window of 1.5 V. The ASC device delivered a maximum energy density of 42.2 W h kg −1 at a power density of 750 W kg −1 .
Deep (>4500 m) sedimentary units in petroliferous basins are a frontier field for petroleum exploration and exploitation worldwide. This study focuses on the northwestern Junggar Basin of NW China ...and presents the results of a comprehensive geochemical analysis of the source rocks and hydrocarbons hosted by deep reservoirs in this region, including data obtained from Rock-Eval pyrolysis, carbon isotope, biomarker, and light hydrocarbon analyses. These data provide insights into the exploration potential of deep hydrocarbons in the study area and in other areas with similar geologic settings (i.e., saline lacustrine petroleum systems). Results indicate that the deep hydrocarbons in the northwestern Junggar Basin are dominated by oil, with both the oil and natural gas being derived mainly from the lower Permian Fengcheng Formation. This formation was deposited in a heterogeneous saline lacustrine environment, which led to the generation of geochemically diverse oil compositions. Consequently, Fengcheng-derived oils can be divided into subcategories based on source rock lithology; i.e., hypersaline alkaline muddy dolomites, saline (dolomitic) mudstones, and brackish mudstones. A small number of deep oils in the study area were derived from the Carboniferous–lower Permian Jiamuhe Formation. The deep hydrocarbons in the study area generally accumulated in near-source environments, indicating that prospective areas are present in the form of Fengcheng-derived oils in the depocenter of the Mahu sag, especially oils derived from hypersaline alkaline muddy dolomites and saline (dolomitic) mudstones. These source rocks are likely to have generated oil even under the highly mature conditions associated with deep burial. This might explain why discoveries within saline lacustrine basins are generally dominated by oil, implying that these conditions might also exist within the deeper parts of saline lacustrine basins worldwide.
•Deep hydrocarbons (oils) in the NW Junggar Basin are mainly derived from brackish–saline rocks.•Oils and source rocks are geochemically diverse including hypersaline, saline, and brackish.•Deep hydrocarbons accumulate in near-source environments.•Saline source rocks are generally favorable for oil generation even under highly mature burial condition.
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