The ongoing pandemic of a new human coronavirus, SARS-CoV-2, has generated enormous global concern. We and others in China were involved in the initial genome sequencing of the virus. Herein, we ...describe what genomic data reveal about the emergence SARS-CoV-2 and discuss the gaps in our understanding of its origins.
A micromechanical study has been conducted on low temperature dwell fatigue resistance in multiphase polycrystalline titanium alloys. The origin of the observed peak in strain rate sensitivity (SRS) ...over temperature has been explained by the transition from high-stress/low-temperature to low-stress/high-temperature thermally activated dislocation escape. The SRS peak is found to depend considerably on the rate sensitive slip systems in hexagonal close packed (HCP) α phase and body centered cubic (BCC) β phase in Ti alloys. This motivates the study of structural rate dependence, using the SRS peak, in commercially important textured multiphase Ti alloys.
It is found that the SRS peak is dependent on texture and phase morphology in multiphase titanium alloys, which is different from some conventional binary alloys. A computational investigation of crystallographic texture shows that stronger rate sensitivity results from polycrystals with higher fractions of grains well-orientated for basal slip activation. This has also been demonstrated in independent experimental studies. Basketweave structures with multiple α variants have been shown to give the lowest SRSs over those with less variant and colony structures. In addition, the SRS peak, for representative textures and morphologies, has been found to be closely related to the creep behaviour in cold dwell fatigue. This understanding is important in microstructural design of titanium alloys for resisting cold dwell fatigue.
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Novel 3D Ni1−xCoxSe2 mesoporous nanosheet networks with tunable stoichiometry are successfully synthesized on Ni foam (Ni1−xCoxSe2 MNSN/NF with x ranging from 0 to 0.35). The collective effects of ...special morphological design and electronic structure engineering enable the integrated electrocatalyst to have very high activity for hydrogen evolution reaction (HER) and excellent stability in a wide pH range. Ni0.89Co0.11Se2 MNSN/NF is revealed to exhibit an overpotential (η10) of 85 mV at −10 mA cm−2 in alkaline medium (pH 14) and η10 of 52 mV in acidic solution (pH 0), which are the best among all selenide‐based electrocatalysts reported thus far. In particular, it is shown for the first time that the catalyst can work efficiently in neutral solution (pH 7) with a record η10 of 82 mV for all noble metal‐free electrocatalysts ever reported. Based on theoretical calculations, it is further verified that the advanced all‐pH HER activity of Ni0.89Co0.11Se2 is originated from the enhanced adsorption of both H+ and H2O induced by the substitutional doping of cobalt at an optimal level. It is believed that the present work provides a valuable route for the design and synthesis of inexpensive and efficient all‐pH HER electrocatalysts.
An integrated electrocatalyst comprising 3D mesoporous Ni0.89Co0.11Se2 nanosheet networks on Ni foam is synthesized, and it demonstrates very high activities and excellent stabilities for hydrogen evolution reaction (HER) in all‐pH conditions. Theoretical calculations verify that electronic structure engineering by optimal Co doping enhances the adsorption of H+ and H2O, leading to the advanced all‐pH HER activity of the catalyst.
The internal structure of oceanic crusts is not well understood due to the limitation of deep drilling. However, that of ophiolites, i.e., on‐land ancient analogs of oceanic lithosphere, could be ...precisely mapped and measured. The Xigaze ophiolite in Tibet has been regarded as “peculiar”, due to the sheeted sill complex in its upper crust, and non‐sheeted diabase sills/dikes crosscutting its mantle and lower crust, which are geometrically different from the primarily vertical sheeted dike complex. Based on extensive field observations, here we present petrological and geochemical data for the Xigaze ophiolite to decipher the origin of sheeted sill complex and its implications for the construction of oceanic crusts. Diabases in the Xigaze ophiolite could be subdivided into sheeted sills, Group 1 non‐sheeted dikes, and Group 2 non‐sheeted sills, based on their orientations. These diabases cut other lithologies, and hence belong to the latest‐stage products. Based on petrological, geochemical, and structural data, we highlight the important role of detachment fault in the generation of sheeted and non‐sheeted sills. During the formation of oceanic crust, large block exhumation, multi‐stage rotations, and foundering are argued here as key mechanisms for the generation of Xigaze sheeted and non‐sheeted dikes/sills, all of which are in the evolution of detachment fault systems. These processes are also not uncommon for asymmetrical segments at modern slow‐spreading and ultraslow‐spreading ridges, but are rare at symmetrical segments. Due to the evolution of detachment fault, the internal structures of (ultra)slow‐spreading ridges are more complex than those at fast‐spreading ridges.
Key Points
The Xigaze ophiolite develops the peculiar sheeted sill complex, which is geometrically different from sheeted dike complex
Generation of sheeted sills is controlled by block exhumation, rotation, and foundering, which are associated with detachment faults
Construction of slower‐spreading oceanic crusts is quite complex, and directly controlled by the evolution of detachment faults
Massive multiple-input multiple-output (M-MIMO) technology is considered to be a key enabling technology for future wireless communication systems. One of the challenges in effectively implementing ...an advanced precoding scheme to a large-scale array antenna is how to reduce the mutual coupling among antenna elements. In this paper, a new concept that is called array-antenna decoupling surface (ADS) for reducing the mutual coupling between antenna elements in a large-scale array antenna is proposed for the first time. An ADS is a thin surface that is composed of a plurality of electrical small metal patches and is placed in front of the array antenna. The partially diffracted waves from the ADS can be controlled to cancel the unwanted coupled waves. Two practical design examples are given to illustrate the design process and considerations, and to demonstrate the usefulness of ADS for the applications of phased array antennas and M-MIMO systems when commonly used precoding schemes are applied. The attractive features of ADS include its applicability to a large-scale array antenna; suitability for a wide range of antenna forms; wide decoupling bandwidth; and simplicity in implementation.
Triple-negative breast cancer (TNBC) is a highly malignant breast cancer subtype with a poor prognosis. Improved insight into the molecular biology basis of TNBC progression is urgently needed. ...Herein, we reported that POLD2 was highly expressed in TNBC and patients with high POLD2 expression in their tumors had poor clinical outcomes. In functional studies, knockdown of POLD2 inhibited the proliferation of TNBC. Mechanistically, we revealed that transcription factor E2F1 directly bound to the promoter of POLD2 and regulated its expression in TNBC cells, which in turn contributed to the proliferation of TNBC. Additionally, rescue experiments validated that E2F1-mediated cell proliferation in TNBC was dependent on POLD2. Taken together, our results elucidated a novel mechanism of the E2F1-POLD2 axis in TNBC proliferation, and POLD2 may be a potential therapeutic target for TNBC treatment.
Magnetized activated carbons (MAC) were prepared by activating rape straw powder, and pyrolyzing at different temperatures, then magnetizing activated carbon by hydrothermal method. MAC-300 had the ...largest adsorption capacity of Pb(II) (253.2 mg/g) and Cd(II) (73.3 mg/g). The adsorption isotherms and kinetics could conform to the Freundlich model and pseudo-second-order kinetic model, respectively, indicating that the adsorptive behavior of the adsorbent mainly depends on the non-uniform active points on the surface of the material. Meanwhile, the thermodynamic parameters showed that the adsorption of Pb(II) and Cd(II) by MAC-300 was a spontaneous and endothermic reaction. The adsorption capacity of MAC-300 could be improved by properly increasing the pH of the original solution. There was competitive adsorption when high-valent ions were present in solution. In combination with various characterizations and comparison tests of samples after adsorption, the adsorption mechanisms include surface electrostatic attraction, surface complexation, and co-precipitation. The results indicated that the MAC material was a potential material to remove heavy metal ions from the aqueous solution.
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•Activation carbon embedded with MnFe2O4 magnetic particles (MAC-T) was fabricated.•MAC-T had excellent ferromagnetic properties, stability, and reusability.•MAC-T showed high adsorption ability for Pb(II) and Cd(II).•The mechanisms were electrostatic attraction, complexation, and co-precipitation.
Inflammatory bowel disease:Pathogenesis Zhang, Yi-Zhen; Li, Yong-Yu
World journal of gastroenterology : WJG,
01/2014, Letnik:
20, Številka:
1
Journal Article
Odprti dostop
Inflammatory bowel disease(IBD),including Crohn’s disease and ulcerative colitis,is characterized by chronic relapsing intestinal inflammation.It has been a worldwide health-care problem with a ...continually increasing incidence.It is thought that IBD results from an aberrant and continuing immune response to the microbes in the gut,catalyzed by the genetic susceptibility of the individual.Although the etiology of IBD remains largely unknown,it involves a complex interaction between the genetic,environmental or microbial factors and the immune responses.Of the four components of IBD pathogenesis,most rapid progress has been made in the genetic study of gut inflammation.The latest internationally collaborative studies have ascertained 163susceptibility gene loci for IBD.The genes implicated in childhood-onset and adult-onset IBD overlap,suggesting similar genetic predispositions.However,the fact that genetic factors account for only a portion of overall disease variance indicates that microbial and environmental factors may interact with genetic elements in the pathogenesis of IBD.Meanwhile,the adaptive immune response has been classically considered to play a major role in the pathogenesis of IBD,as new studies in immunology and genetics have clarified that the innate immune response maintains the same importance in inducing gut inflammation.Recent progress in understanding IBD pathogenesis sheds lights on relevant disease mechanisms,including the innate and adaptive immunity,and the interactions between genetic factors and microbial and environmental cues.In this review,we provide an update on the major advances that have occurred in above areas.
Two-dimensional nanofluidic channels are emerging candidates for capturing osmotic energy from salinity gradients. However, present two-dimensional nanofluidic architectures are generally constructed ...by simple stacking of pristine nanosheets with insufficient charge densities, and exhibit low-efficiency transport dynamics, consequently resulting in undesirable power densities (<1 W m
). Here we demonstrate MXene/Kevlar nanofiber composite membranes as high-performance nanofluidic osmotic power generators. By mixing river water and sea water, the power density can achieve a value of approximately 4.1 W m
, outperforming the state-of-art membranes to the best of our knowledge. Experiments and theoretical calculations reveal that the correlation between surface charge of MXene and space charge brought by nanofibers plays a key role in modulating ion diffusion and can synergistically contribute to such a considerable energy conversion performance. This work highlights the promise in the coupling of surface charge and space charge in nanoconfinement for energy conversion driven by chemical potential gradients.
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