To clarify the size distribution of different types of shale pores, nine Sinian–Cambrian shale samples from South China were examined using ion-milling, FE-SEM, nitrogen adsorption and mercury ...intrusion. Image-based point counting data indicated that nanopores are predominant, whereas pores larger than 1μm are absent. Organic matter-hosted pores dominate below 130nm, whereas intraparticle pores within carbonate, probably caused by dissolution, constitute most pores larger than 400nm. The small amount of residual intraparticle and interparticle pores associated with rigid minerals mostly range from 50nm to 250nm. A positive relationship was found between the TOC and total pore volume measured by nitrogen and mercury. The mercury volume of pores larger than ~300nm increased with increasing dolomite and decreasing clay mineral content. The statistics from image-analysis and the relationship between pore volume and shale components were in good agreement, indicating that different types of pores have their own relative restricted size range. Generally, intraP pores are larger than pores associated with rigid minerals, whereas the OM pores and interP pores associated with OM or clay are the smallest. Through a comparison with other less matured shale formations, the highly matured (equivalent vitrinite reflectance above 3%) Sinian–Cambrian shale in South China was characterized in this study as those with smaller interP pores, which is probably due to a stronger compacting effect.
•OM pores contribute most to the pore system of Sinian–Cambrian organic-rich shale.•Different types of pores in shale have their own relative restricted size range.•Overmature shale have smaller interP pores due to a stronger compacting effect.
Display omitted
•Polyaniline nanolayer was designed to improve the interfacial interaction in carbon fiber/epoxy composites.•The carbon fiber/epoxy composites showed a superior electromagnetic ...interference shielding effectiveness of 54.8 dB.•The carbon fiber/epoxy composites exhibited excellent mechanical properties, with an interlaminar shear strength of 72.8 MPa.•An interfacial enhancement mechanism was proposed to explain the excellent mechanical properties of the composites.
The development of carbon fiber-reinforced polymers (CFRPs) with high electromagnetic interference (EMI) shielding effectiveness is highly desirable for engineering applications. Nevertheless, poor interfacial adhesion between carbon fibers (CFs) and polymer matrix remains a serious issue. Herein, a mechanically enhanced CF/epoxy composite with highly efficient EMI shielding was fabricated through in-situ polymerization of polyaniline (PANI) nanolayer. The PANI nanolayer improved the interfacial adhesion in the composites via the entanglement of molecular chains, π–π stacking, and chemical bonding et al. The resulting CF/PANI/epoxy composite exhibited an interlaminar shear strength of 72.8 MPa, which was a 24% improvement over 58.5 MPa for the virgin CF/epoxy composite. Moreover, an excellent EMI shielding effectiveness of 54.8 dB was achieved, which was 58% higher than that of the virgin CF/epoxy composite. This could be attributed to the significant enhancement in conduction loss, interfacial polarization loss, and multiple reflections with the help of PANI nanolayer. This study provides a novel strategy for the development of high-performance CFRPs for efficient EMI shielding.
The Guangou bauxite deposit in western Henan, China, is located in the North China Block and to the north of the North Qinling orogenic belt. The orebody is hosted within the lower member of the ...Carboniferous Benxi Formation, which overlies unconformably upon the Ordovician Majiagou Formation. In the lower member of the Benxi Formation, the bauxite orebody (with a diaspore–illite–anatase mineral assemblage) is sandwiched between underlying ferric clay (illite–hematite–goethite) and overlying top clay (kaolinite–quartz–goethite). According to field observations and geochemical evidence including trace- and rare-earth-element (REE) compositions, especially Zr/Hf ratios, the ferric clays were weathered from the underlying argillaceous limestones in the Majiagou Formation. During this weathering process, trace elements S, Zn, Ni, Cr, V, Sc, F, Ba, and Be are depleted; Li, Rb, and B are enriched; and Zr, Hf, Bi, Ta, Ga, Nb, and Th are relatively immobile. REEs exhibit evident differentiation with enrichment of La, Ce, Pr, and Nd and depletion of Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. The bauxite formed in weak reducing, slightly basic water conditions according to the geneses of coexisting diaspore and anatase, and it was altered during the epigenetic and second exposure periods, forming kaolinite and goethite, respectively. Interelemental relationship analyses of the ores suggest that the elemental behaviors of trace elements and REEs in the bauxitization process are mainly controlled by the mineral compositions in bauxite ore and chemical properties of the elements. For instance, zircon, rutile, and anatase contain Zr, Hf, Nb, Ta, W, and U. Based on geochemical evidence, together with age data and chemical compositions of the detrital minerals, both distant igneous rocks in the plate margin and Paleozoic carbonates and Precambrian rocks inside North China Block provide the miscellaneous material for the bauxite ore and the top clay.
•Genesis of major minerals and ore-forming environment are discussed.•Elemental behaviors of elements in bauxitization are studied.•Parent rocks and ore-forming process are updated.
Improvement in living standards has led to the development and utilization of forest green foods. The study seeks to examine the foundation and potential of forest green food industry in Yunnan ...Province. By constructing the industrial competitive advantage model, this paper measured and analyzed the competitiveness of forest green food industry in Yunnan Province from 2016 to 2020 by using fuzzy evaluation method and AHP. The conclusions were as follows: (1) The competitiveness of forest green food industry in Yunnan Province was at a medium level with competitiveness index of 83.98. (2) The competitive advantage of forest green food industry in Yunnan Province mainly depended on key factors such as natural endowment and education level. The area is however not having comparative advantage in general factors and important factors. Therefore, there is the need to put in place measures to realise the full potential of forest green food industry in the area by providing players in the sector with requisite skills.
Every day, numerous polymer materials are fabricated into specific articles with definite sizes, shapes and forms using polymer processing. Obviously, polymer processing has become one of the most ...active areas of polymer science and engineering. The key is to profoundly explore the processing-structure-performance relations for various polymer-based materials. From a structure-dominated performance point of view, the ultimate physical/chemical properties of polymer articles are directly related to their internal multiscale (hierarchical) structures, which range from the molecular, nanometer, submicron and micron scale to the mesoscopic level. Because the features of hierarchical structures strongly depend on the external fields that are imposed during processing, many structural items, such as the chain configuration, crystalline polymorphism, orientation and phase separation behavior, can be well or precisely controlled, resulting in significant variations in the hierarchical structure. Due to developments in mechanical techniques, various external fields, such as thermal, shear, extension, ultrasonic, electronic, magnetic and super-critical fluid fields, may be introduced into polymer processing, leading to significant improvements in the tailoring of the microstructure/morphology via processing. This process is characterized by an “externally applied field determined hierarchical structure”, i.e., a “structuring” processing, which represents an advanced trend in modern polymer processing and is the topic of this review. This contribution includes the following: (1) an introduction, (2) the in situ monitoring of polymer processing, (3) progress in “structuring” processing and (4) concluding remarks and perspectives.
Display omitted
•The lower pisolitic bauxite horizon was formed as terrestrial deposition.•The upper oolitic bauxite horizon was marine deposition during submergence.•Li, V, Cr, and Ga are associated ...with clay minerals, rather than Al hydroxides.•Karst bauxite-bearing sequences are a new potential resource for Li.
Bauxite-bearing sequences are not only the main economic sources of Aluminum, but also of many critical metals. The distribution of critical metals was determined from six bauxite profiles in Baofeng, and an evolution model was proposed for the formation of bauxite-bearing sequences. Following a terrestrial deposition of the lower pisolitic bauxite horizon and the underlying clayey layer, transportation and redeposition of bauxitic materials during submergence led to the formation of the upper bauxite horizon presenting finely-clastic and oolitic textures, as well as the intercalated clayey layers. Both bauxite ores and clay samples contain highly elevated contents of Li, B, Sc, V, Ga, Zr, Nb, W and total REEs. Li contents are extremely low in high-grade bauxite ores (10.92–44.77 ppm), compared to highly elevated values in low-grade bauxite ores (35.81–1601 ppm) and clay samples (38.54–1965 ppm), enlightening a new potential resource for Li, the bauxite-bearing sequences resting on karstified carbonate. The distribution pattern of Ga is similar to that of Li, and the correlation analysis indicates that Ga is primarily associated with silicates, i.e. clay minerals. The vertical distribution of Li, B, V, Cr and Ga shares the same pattern, similar to that of K2O and SiO2, being highly enriched in clayey layers relative to bauxite horizons. Both Sc and total REEs are also highly enriched in Baofeng bauxite profiles, highlighting a potential Sc and REEs resource.
China is highly dependent on foreign oil and gas, and the exploration and exploitation of shale gas is an important way to alleviate the energy and environmental pressure of China. Although a series ...of significant progress has been made in a short time, China is still at the crossroads of shale gas exploration direction. Therefore, this paper systematically reviews the particularity of shale gas geological conditions in China, and points out China's exploration direction of shale gas in different fields combined with the research achievements of shale gas accumulation mechanism. The following results were obtained. (1) China's shale gas exploration fields can be divided into three major parts, i.e., marine, continental and marine–continental transitional facies. The geological characteristics of shale gas in North China, Yangtze and Tarim plates are different. The interaction of multiple factors, including tectonic and sedimentary evolution, shale gas accumulation, late-stage transformation and etc., has led the complexity of the geological distribution and the diversity of exploration fields of shale gas in China. (2) The organic pores and fractures of marine shale are developed. The Ordovician Wufeng-Silurian Longmaxi Formation will still be the primary target of shale gas exploration in future. Meanwhile, the Cambrian Niutitang and Sinian Doushantuo Formation in the Yangtze region, the Devonian Luofu and Carboniferous Jiusi Formation in the Yunnan-Guizhou-Guangxi region, the Jixianian Hongshuizhuang and Mesoproterozoic Xiamaling Formation will be the targets of strategic breakthrough in shale gas exploration. (3) The structural deep and slope of middle-large basins and the sedimentation centers of small-middle basins are the main directions of continental shale gas exploration. Inter-laminar cracks and intergranular pores are well developed in continental shale. The coupling of various organic matter types and thermal evolution results in the symbiosis of shale oil and shale gas, which will become an important field for further exploration of continental shale gas. (4) The marine–continental transitional shale, which mainly formed in Late Carboniferous-Permian, is characterized by cyclic association with sandstone, mudstone, coal and carbonate. Diagenetic fractures are well developed in transitional shale. The favorable structural and diagenetic preservation are the two major factors for the enrichment of this type of shale gas. The flat-lagoon and delta sedimentary systems, middle-large superimposed and small-middle residual basins, and deep layers with quality caprock and good structural preservation are the favorable directions for shale gas exploration in transitional facies.
Morphological changes are a very common and effective strategy for pathogens to survive in the mammalian host. During interactions with their host, human pathogenic fungi undergo an array of ...morphological changes that are tightly associated with virulence.
switches between yeast cells and hyphae during infection. Thermally dimorphic pathogens, such as
and
species transform from hyphal growth to yeast cells in response to host stimuli.
and
species produce spherules and cysts, respectively, which allow for the production of offspring in a protected environment. Finally,
species suppress hyphal growth and instead produce an array of yeast cells-from large polyploid titan cells to micro cells. While the morphology changes produced by human fungal pathogens are diverse, they all allow for the pathogens to evade, manipulate, and overcome host immune defenses to cause disease. In this review, we summarize the morphology changes in human fungal pathogens-focusing on morphological features, stimuli, and mechanisms of formation in the host.
Defect engineering and heteroatom doping can significantly enhance the activity of zinc-aluminum layered double hydroxides (ZnAl-LDHs) in photocatalytic CO2 reduction to fuel. However, the in-depth ...understanding of the associated intrinsic mechanisms is limited. Herein, we systematically investigated Zn vacancies (VZn), oxygen vacancies (VO), and Cu doping on the geometry and electronic structure of ZnAl-LDH using density functional theory (DFT). We also revealed the related reaction mechanism. The results reveal the concerted roles of VO, VZn, and doped-Cu facilitate the formation of the unsaturated metal complexes (Znδ+-VO and Cuδ+-VO). They can localize the charge density distribution, function as new active centers, and form the intermediate band. Simultaneously, the intermediate band of functionalized ZnAl-LDHs narrows the band gap and lowers the band edge location. Therefore, it can broaden the absorption range of light and improve the selectivity of CO. Additionally, the unsaturated metal complex lowers the Gibbs free energy barrier for effective CO2 activation by bringing the d-band center level closer to the Fermi level. The work provided guidance for developing LDH photocatalysts with high activity and selectivity.
Cryptococcus neoformans is a major life-threatening fungal pathogen. In response to the stress of the host environment, C. neoformans produces large polyploid titan cells. Titan cell production ...enhances the virulence of C. neoformans, yet whether the polyploid aspect of titan cells is specifically influential remains unknown. We show that titan cells were more likely to survive and produce offspring under multiple stress conditions than typical cells and that even their normally sized daughters maintained an advantage over typical cells in continued exposure to stress. Although polyploid titan cells generated haploid daughter cell progeny upon in vitro replication under nutrient-replete conditions, titan cells treated with the antifungal drug fluconazole produced fluconazole-resistant diploid and aneuploid daughter cells. Interestingly, a single titan mother cell was capable of generating multiple types of aneuploid daughter cells. The increased survival and genomic diversity of titan cell progeny promote rapid adaptation to new or high-stress conditions.
The ability to adapt to stress is a key element for survival of pathogenic microbes in the host and thus plays an important role in pathogenesis. Here we investigated the predominantly haploid human fungal pathogen Cryptococcus neoformans, which is capable of ploidy and cell size increases during infection through production of titan cells. The enlarged polyploid titan cells are then able to rapidly undergo ploidy reduction to generate progeny with reduced ploidy and/or aneuploidy. Under stressful conditions, titan cell progeny have a growth and survival advantage over typical cell progeny. Understanding how titan cells enhance the rate of cryptococcal adaptation under stress conditions may assist in the development of novel drugs aimed at blocking ploidy transitions.
PDF
