Mimicking natural structures has been highly pursued in the fabrication of synthetic polymeric materials due to its potential in breaking the bottlenecks in mechanical properties and extending the ...applications of polymeric materials. Recently, it has been revealed that the energy dissipating mechanisms
via
sacrificial bonds are among the important factors which account for strong and tough attributes of natural materials. Great progress in synthesis of polymeric materials consisting of sacrificial bonds has been achieved. The present review aims at (1) summarizing progress in the mechanics and chemistry of sacrificial bond bearing polymers, (2) describing the mechanisms of sacrificial bonds in strengthening/toughening polymers based on studies by single-molecule force spectroscopy, chromophore incorporation and constitutive laws, (3) presenting synthesis methods for sacrificial bonding including dual-crosslink, dual/multiple-network, and sacrificial interfaces, (4) discussing the important advances in engineering sacrificial bonding into hydrogels, biomimetic structures and elastomers, and (5) suggesting future works on molecular simulation, viscoelasticity, construction of sacrificial interfaces and sacrificial bonds with high dissociative temperature. It is hoped that this review will provide guidance for further development of sacrificial bonding strategies in polymeric materials.
This review focuses on the mechanisms, designs, and applications of bio-inspired sacrificial bonds in artificial polymeric materials.
As the main candidates in the field of ultra‐high temperature ceramics, high entropy carbides/borides (HECs/HEBs) have good oxidation resistance properties, high hardness, as well as excellent ...thermal and electrical conductivities, which are the focused points of research nowadays. In the current study, (Hf,Ta,Zr,Nb,Mo,Ti)C powders were successfully synthesized by a three‐step process, including the mixing process of raw oxides and carbon black with spaying Fe(NO3)3 solution, carbothermal reduction and subsequent calcium posttreatment. For the preparation of (Hf,Ta,Zr,Nb,Mo,Ti)B2 powders, during the calcium posttreatment process, equal stoichiometric ratio of B4C was added for the purpose of boriding reaction. The relevant X‐ray diffraction and SEM characterizations indicate the successful preparations of face‐centered cubic HECs and hexagonal HEBs. However, slight Mo local segregation was found in the prepared (Hf,Ta,Zr,Nb,Mo,Ti)B2 powders. The iron generated from Fe(NO3)3 promotes the solid solution process between monocarbides during the carbothermal reduction process via the dissolution‐diffusion‐precipitation mechanism. In the calcium posttreatment process, the liquid calcium ensures the boriding reaction take place at a low temperature. In addition, the residual carbon could be combined with calcium to generate CaC2 which is easy to be removed by acid leaching, and meanwhile, the added Fe could also be finally eliminated to produce pure HEC/HEB powders. The current method does not require the long‐time high energy ball milling of raw materials, but only simple and mild mixing is enough. Therefore, such a facile route has a great potential application prospect for industrially preparing high entropy phase powders in a large scale.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Hepatitis D virus (HDV) is a defective virus that completes its life cycle only with hepatitis B virus (HBV). The HBV with HDV super-infection has been considered as one of the most severe forms of ...the chronic viral hepatitis. However, there is a scarcity of data on the global burden of HDV infection.
We searched PubMed, Embase, Cochrane Library and China Knowledge Resource Integrated databases from 1 January 1977 to 31 December 2016. We included studies with a minimum sample size of 50 patients. Our study analysed data from a total of 40 million individuals to estimate the prevalence of HDV by using Der-Simonian Laird random-effects model. The data were further categorised according to risk factors.
From a total of 2717 initially identified studies, only 182 articles from 61 countries and regions met the final inclusion criteria. The overall prevalence of HDV was 0.98% (95% CI 0.61 to 1.42). In HBsAg-positive population, HDV pooled prevalence was 14.57% (95% CI 12.93 to 16.27): Seroprevalence was 10.58% (95% CI 9.14 to 12.11) in mixed population without risk factors of intravenous drug use (IVDU) and high-risk sexual behaviour (HRSB). It was 37.57% (95% CI 29.30 to 46.20) in the IVDU population and 17.01% (95% CI 10.69 to 24.34) in HRSB population.
We found that approximately 10.58% HBsAg carriers (without IVDU and HRSB) were coinfected with HDV, which is twofold of what has been estimated before. We also noted a substantially higher HDV prevalence in the IVDU and HRSB population. Our study highlights the need for increased focus on the routine HDV screening and rigorous implementation of HBV vaccine programme.
Improvement of crop drought resistance and water-use efficiency (WUE) has been a major endeavor in agriculture. Arabidopsis ENHANCED DROUGHT TOLERANCE1/HOMEODOMAIN GLABROUS11 (AtEDT1/HDG11), a ...homeodomain-START transcription factor we previously identified from the enhanced drought tolerance1 mutant (edt1), has been demonstrated to improve drought tolerance and WUE significantly in multiple plant species when constitutively overexpressed.
Here, we report the genetic evidence suggesting a genetic pathway, which consists of EDT1/HDG11, ERECTA, and E2Fa loci, and regulates WUE by modulating stomatal density. AtEDT1/HDG11 transcriptionally activates ERECTA by binding to homeodomain-binding (HD) cis-elements in the ERECTA promoter. ERECTA, in turn, depends on E2Fa to modulate the expression of cell cycle-related genes.
This modulation affects the transition from mitosis to endocycle, leading to increased ploidy levels in leaf cells, and therefore increased cell size and decreased stomatal density.
Our results suggest a possible EDT1/HDG11-ERECTA-E2Fa genetic pathway that reduces stomatal density by increasing cell size and provide a new avenue to improve WUE of crops.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
In this paper, a new method for preparing ultrafine tungsten-molybdenum composite powders has been proposed. The carbothermic pre-reduction of the mixture of molybdenum trioxide and tungsten trioxide ...with insufficient carbon black under argon atmosphere was carried out, to generate the pre-reduced tungsten-molybdenum composite powder containing a small amount of residual dioxide. Thereafter, the obtained reaction product was subjected to hydrogen reduction to remove the residual dioxide and generate pure tungsten-molybdenum composite powder with the particle size of 100–200 nm. Two kinds of ultrafine tungsten-molybdenum alloy powders (Mo-30 wt% W, Mo-70 wt% W) were prepared. The residual carbon of the finally obtained product was about 0.01–0.02 wt% after the hydrogen reduction. The sintering behavior of ultrafine W–Mo powders and the properties of sintered samples are investigated. After sintering ultrafine Mo-30 wt% W and Mo-70 wt% W powders at 1600 °C, the relative density of the sintered compacts was about 99%, 97%, and the microhardness were 287 HV and 350 HV, respectively. Meanwhile, as increasing the sintering temperature from 1200 to 1600 °C, the relative density and microhardness of the compacts gradually increased.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Precise genome editing via homology-directed repair (HDR) after double-stranded DNA (dsDNA) cleavage facilitates functional genomic research and holds promise for gene therapy. However, HDR ...efficiency remains low in some cell types, including some of great research and clinical interest, such as human induced pluripotent stem cells (iPSCs).
Here, we show that a double cut HDR donor, which is flanked by single guide RNA (sgRNA)-PAM sequences and is released after CRISPR/Cas9 cleavage, increases HDR efficiency by twofold to fivefold relative to circular plasmid donors at one genomic locus in 293 T cells and two distinct genomic loci in iPSCs. We find that a 600 bp homology in both arms leads to high-level genome knockin, with 97-100% of the donor insertion events being mediated by HDR. The combined use of CCND1, a cyclin that functions in G1/S transition, and nocodazole, a G2/M phase synchronizer, doubles HDR efficiency to up to 30% in iPSCs.
Taken together, these findings provide guidance for the design of HDR donor vectors and the selection of HDR-enhancing factors for applications in genome research and precision medicine.
► Operations of the Three Gorges Dam (TGD) strongly affected the Yangtze River discharge. ► TGD effect has strong seasonal variations. ► TGD caused changes in the Yangtze River discharge altered ...relationship of the Yangtze River and the Poyang Lake. ► River forcing on the lake weakened and caused severe reduction of Poyang Lake water storage.
The Three Gorges Dam (TGD) has been in operation since 2003. Over the operation period from 2003–2008, data have been collected for preliminary evaluations of actual effects of the TGD on the Yangtze River flow and river interactions with downstream lakes and tributaries. These effects are examined in this study, after the climate influence was minimized by comparing hydrological changes between years of similar climate conditions before and after the operation of the TGD. Major results show that the TGD operation has affected the Yangtze River discharge and water level. The significance of these effects varies seasonally and with different locations along the river. The seasonal variation follows the TGD’s seasonal impounding and releasing of water. The magnitude of the effects is dependent on the impounding/releasing rate and the seasonal flow of the river. The most significant effects are confined in the river reach near the TGD and are as great as five times those of sections downstream. The weakening and diminishing of effect of the TGD is primarily because of “dilutions” to the effect by inflows to the Yangtze River from downstream tributaries.
Changes in the Yangtze River discharge caused by the TGD have further altered the interrelationship between the river and Poyang Lake, disturbing the lake basin hydrological processes and water resources. A major consequence of such changes has been a weakening in the river forcing on the lake, allowing more lake flow to the river from July–March. This effect of the TGD may partially fulfill the TGD’s mission to mitigate flood risks in the lake basin, especially during the peak wet season of the Yangtze River basin from July–September. In the 6
years since the TGD operation began the annual average number of severe outflow events of rates of ⩾3000
m
3
s
−1 from the lake in July–September has increased by 74. It has also resulted in reduction of water storage in Poyang Lake. Results of this study point to strong needs for working strategies to balance the TGD impacts on flood control and water resources as well as their societal and ecological consequences in the Poyang Lake basin. Meanwhile, in the context of studies of impacts of large dams this study shows an example of extending the previous studies in the dam–river setting to a new dam–river–lake construct.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
MoSi2-Al2O3 composites with various volume fractions of Al2O3 from 0 to 40 vol% were fabricated by pressureless sintering at 1550 ℃. MoSi2 powder was prepared by silicothermic reduction of MoS2. ...Microstructure, mechanical properties, electrical resistivity and oxidation behavior of composites were experimentally examined to investigate the influence of Al2O3 addition. The results demonstrated that proper introduction of Al2O3 contributed to improving the oxidation resistance and mechanical properties. Among them, MoSi2-20 vol%Al2O3 composite presented excellent comprehensive properties and oxidation resistance. The oxide scale consisting of SiO2 and Al2O3 was formed on the substrate and effectively prevented the inward diffusion of oxygen.
•MoS2 was used as a Mo source to prepare ultrafine MoSi2 powder.•Effects of Al2O3 addition content on properties of sintered MoSi2-Al2O3 was studied.•The SiO2 film incorporating Al2O3 provided greater protective.•MoSi2-20 vol% Al2O3 composites performed excellent comprehensive performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Due to strong anti‐poisoning ability, good emission stability, high emission current density, lanthanum hexaboride (LaB6) and cerium hexaboride (CeB6) have been maturely applied in electron emission ...emitter. In this paper, a new manufacturing method for LaB6 (or CeB6) powder was proposed by using La2O3 (or CeO2), B4C, and Al as raw materials. After high‐temperature reaction in the range of 1673–1773 K and the following alkaline leaching at 90°C, LaB6 or CeB6 powder with particle size of about 10 μm was obtained. Furthermore, by Al metal flux method, the obtained powder was used to manufacture single crystal block with size of several millimeters.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Attached microalgae cultivation could simplify the microalgae harvest process and reduce its associated cost, which has attracted much attention recently. In this paper, the reactor patterns, ...advantages, microalgae biomass productivity, influencing factors and the microalgae physicochemical properties in the attached microalgae cultivation was summarized to show the sketch of this novel microalgae cultivation. It was concluded that the attached microalgae cultivation is advantageous in achieving less water and space consumption, higher water treatment potential and higher biomass productivity compared with the traditional suspended microalgae cultivation. The accumulation of the attached microalgae biomass showed a linear increase with culture time with the largest productivity up to 20.7 g m−2 d−1. Chlorella and Scenedesmus were the top two species that have been studied in attached culture system. Cellulose acetate/nitrate membrane, polycarbonate membrane and cotton were the most popular materials used owing to their high hydrophilicity and wide availability. Flow rate, nutrients, light, CO2 and other factors could affect the attached microalgae productivity and the physicochemical property in a way different from the suspended microalgae, which were described in detail in this review. At last, some technical bottlenecks and the corresponding solvents in the attached microalgae were suggested.
•Attached cultivation could simplify microalgae harvest process and reduce its cost.•Attached microalgae showed a linear growth with the rate up to 20.7 g m−2 d−1.•Algae species, support media and nutrients affected attached microalgae growth.•Physicochemical property and their influence factors varied with culture patterns.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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