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Transverse rectangular microgrooves with local machining flaw are investigated using direct numerical simulations from the viewpoint of suppressing the second-mode instability in a Mach 6 hypersonic boundary layer. Two types of machining flaw are modeled for the local deformation of microgrooves, i.e., chamfered and protruded ones. The effect of locally deformed microgrooves on the boundary-layer stability is studied by superposing the second-mode disturbance to the base flow of the boundary layer. The investigated unstable second mode is 400 kHz, and the microgrooves are installed in its synchronous region. The results show that compression and expansion waves are generated on the surface of the deformed microgrooves, and microscale separation bubbles are formed at the rear edge of the deformed microgrooves. With the increase of local deformation height of microgrooves, the suppression effect of the second-mode disturbance gradually increases. As the deformation height reaches 0.09 mm, the amplitude inhibition rate of locally deformed microgrooves on the second-mode disturbance reaches 44.7%, compared to that of the regular one.

Over the past decade, the cast aluminum alloys with excellent mechanical and conductivity properties have emerged as potential materials for thermal management. However, the traditional Al-Si based alloys are difficult to make significant breakthroughs in conductivity performance. The hypoeutectic Al-5Ni alloy also possesses sound castability and is expected to be applied in thermal management applications. In this study, the effects of ytterbium (Yb element) at 0.0–0.5 wt% on the microstructures as well as the electrical/thermal conductivity and mechanical properties of the Al-5Ni alloy was systematically investigated. The experimental results indicate that the addition of Yb at a relatively low amount not only reduces the secondary dendrite arm spacing of the α-Al grains, but also modifies the morphology and distribution of eutectic boundary phase. Moreover, it is found that the dosage of Yb at 0.3 wt% in the Al-5Ni alloy can simultaneously improve the yield strength, ultimate tensile strength and electrical/thermal conductivity. The strengthening and toughening of the Al-5Ni alloy are mainly attributed to the decrease of secondary dendrite arm spacing and the improvement of eutectic phases. The TEM/SAED analysis indicates that the ytterbium in Al-5Ni alloy would form Al3Yb phase, which mainly agglomerates in the Al3Ni phase region. This phase is helpful to decrease the solubility of impurity elements (e.g., Fe and Si) in the α-Al matrix, which is beneficial to electrical/thermal conductivity. The value of this study lays foundation for manufacturing Al-Ni alloys with high thermal conductivity and acceptable mechanical properties.

SUMO modification regulates diverse cellular processes by targeting hundreds of proteins. However, the limited number of sumoylation enzymes raises the question of how such a large number of substrates are efficiently modified. Specifically, how genome maintenance factors are dynamically sumoylated at DNA replication and repair sites to modulate their functions is poorly understood. Here, we demonstrate a role for the conserved yeast Esc2 protein in this process by acting as a SUMO E2 cofactor. Esc2 is required for genome stability and binds to Holliday junctions and replication fork structures. Our targeted screen found that Esc2 promotes the sumoylation of a Holliday junction dissolution complex and specific replisome proteins. Esc2 does not elicit these effects via stable interactions with substrates or their common SUMO E3. Rather, we show that a SUMO-like domain of Esc2 stimulates sumoylation by exploiting a noncovalent SUMO binding site on the E2 enzyme. This role of Esc2 in sumoylation is required for Holliday junction clearance and genome stability. Our findings thus suggest that Esc2 acts as a SUMO E2 cofactor at distinct DNA structures to promote the sumoylation of specific substrates and genome maintenance.

The boundary-layer receptivity of the second mode to a slow acoustic wave is investigated using direct numerical simulation for a Mach 6 flow over a blunt cone with the nose radius of 5.08 mm. The ...

In this paper, the optimum fluoride component in the multifunctional refining flux used for recycling aluminum scrap was determined. Theoretical analysis of solid fluxing shows that strong stripping ability of oxide layer on aluminum surface for the flux and appropriate interfacial tensions between Al melt / inclusion (σM-I), flux / inclusion (σF-I), and flux / Al melt (σF-M) are indispensable for making the flux achieve the properties of covering, drossing, and cleaning simultaneously. In term of four preliminarily selected fluoride salts, i.e., KF, AlF3, K3AlF6 and KAlF4, the results of interfacial tension measurements indicates that, combined addition of A-type fluoride (KF) and B-type fluoride (AlF3, K3AlF6 and KAlF4) to equimolar NaCl-KCl can just offset the shortage of single addition of KF which means worsening the separating effect of flux from melt surface and weakening the wettability of flux on the inclusions due to the lower σF-M and the higher σF-I respectively. Additionally, coalescence behaviors of aluminum droplets in molten fluxes reveals that, KF, K3AlF6 or KAlF4 possesses stronger stripping ability of oxide layer, while the stripping ability of oxide layer for AlF3 is weaker. Ultimately, the combination of KF with K3AlF6 or/and KAlF4 is ascertained to be an optimum selection for fluoride component in the multifunctional refining flux.

Telomerase is crucial for telomere maintenance and genome integrity. The most salient feature of Tetrahymena telomerase is that its CST subcomplex (p75-p45-p19) is tethered to the telomerase catalytic core by interacting with the hub p50. Although the cryoelectron microscopy (cryo-EM) structures of Tetrahymena telomerase have recently been reported, the mechanisms of how and why p50 bridges the CST subcomplex to the telomerase catalytic core remain unclear. Here, we present the nuclear magnetic resonance (NMR) structure of the p75

Soil biota, across multitrophic levels, regulates nutrient cycling and plant performance, and thereby play an important role in delivering multiple ecosystem functions. Soil nematodes occupy diverse positions in the soil food web, such as herbivores, bacterivores, fungivores, omnivores, and predators. Therefore, soil nematodes are usually considered as potential bio-indicators of soil quality or soil health under agricultural managements. However, there is a knowledge gap on how nematode multitrophic biodiversity (here the numbers of nematode trophic groups) affects soil multifunctionality.This study combined field and laboratory experimental approaches to quantify and disentangle the aforementioned issue. First, we explored the impacts of compost application on nematode assemblages as well as multifunctionality based on a long-term field experiment. Results showed that compost application stimulated multitrophic biodiversity by the increase of microbivore and omnivore-predator abundance, while decreasing the herbivores. Besides, the increase of nematode multitrophic biodiversity was accompanied with the soil multifuctionality. Then a complete factorial design microcosm experiment was conducted with manipulating nematode trophic levels (microbivores, herbivores and omnivore-carnivores) to test the hypothesis that increasing multitrophic biodiversity will lead to higher soil multifuctionality as indicated by plant growth and defense to the pests. Consistent with the hypothesis, we found that integrating different trophic levels, i.e. maximum multitrophic biodiversity, could promote plant growth and notably the resistance to pest infestation through changing plant chemical composition. Particularly, we found microbivores reduced root biomass while omnivore-carnivores increased plant shoot biomass. The presence of omnivore-carnivores could suppress the abundance of insect (brown planthoppers) by regulating soil microbiome. In summary, the increment of soil multitrophic biodiversity have multifunctional consequence.Overall, we provide direct experimental evidence for the multifunctional roles of soil multitrophic biodiversity. Further, soil organic management practices, regardless of organic amendments, non-tillage or growing cover crops, that improving soil habitat like resource and structure, and consequently promoting soil biodiversity especially higher-level biotic associations or trophic interactions may ultimately contribute to sustaining multiple ecosystem services including both crop productivity and pathogen controls. Such knowledge helps advance the mechanical understanding of biotic drivers of soil ecosystem functioning. It also highlights that organic management could strengthen the carbon-based ecosystem services if considering the extra benefits provided by soil biodiversity. Overall, our study corroborated organic management will be crucial to implement an ecologically multifunctional agriculture.

Background TRIM26 is an E3 ubiquitin ligase that has been shown to regulate tumor progression. However, the role of TRIM26 in gastric cancer (GC) remains unclear. The purpose of this study is to investigate the role and mechanism of TRIM26 in GC. Methods CCK-8 assay, wound healing assay and Transwell invasion assay were used to explore the specific role of TRIM26 in GC cells. Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression levels of TRIM26, SLC7A11, COX-2, Glutathione peroxidase 4 (GPX4) and other related genes in cells. The levels of GSH, MDA and ROS were detected by kits. Results The expression of TRIM26 was down-regulated in GC tissues and cells. Low expression of TRIM26 enhanced the viability, migration activity and invasive ability of MGC-803 cells. Overexpression of TRIM26 significantly reduced cell viability, migration and invasion abilities. Further studies found that TRIM26 participated in the process of ferroptosis by regulating the expression of SLC7A11, thereby affecting the development of GC. Conclusion We demonstrated for the first time that TRIM26 inhibits the proliferation, migration and invasion of GC cells by regulating SLC7A11-mediated ferroptosis. TRIM26 may be a new target for the clinical treatment of GC.

Lysine acetyltransferase 7 (KAT7) was upregulated in gastric cancer (GC) patient tissues, and associated with poor prognosis and metastasis. However, its specific role in GC remains unclear. This study aimed to annotate the role of KAT7 in GC cells. The results showed that the overexpression of KAT7 promoted cell growth, migration, and invasion, while KAT7 inhibition has the opposite effect. Besides, KAT7 participated in cell cycle phase distribution and epithelial-mesenchymal transition (EMT) process of GC cells. In addition, KAT7 promoted the transcription and nuclear translocation of Yes-associated protein 1 (YAP1) in MKN45 cells. Silence of YAP1 partly reversed the promoting effect of KAT7 on GC cells progression. In summary, this study indicates that KAT7 promoted GC cells progression through promoting YAP1 activation, contributes to understand the specific role of KAT7 in GC.

Gametogenesis is an essential step for malaria parasite transmission and is activated in mosquito by signals including temperature drop, pH change, and mosquito-derived xanthurenic acid (XA). Recently, a membrane protein gametogenesis essential protein 1 (GEP1) was found to be responsible for sensing these signals and interacting with a giant guanylate cyclase α (GCα) to activate the cGMP-PKG-Ca2+ signaling pathway for malaria parasite gametogenesis. However, the molecular mechanisms for this process remain unclear. In this study, we used AlphaFold2 to predict the structure of GEP1 and found that it consists of a conserved N-terminal helical domain and a transmembrane domain that adopts a structure similar to that of cationic amino acid transporters. Molecular docking results showed that XA binds to GEP1 via a pocket similar to the ligand binding sites of known amino acid transporters. In addition, truncations of this N-terminal sequence significantly enhanced the expression, solubility, and stability of GEP1. In addition, we found that GEP1 interacts with GCα via its C-terminal region, which is interrupted by mutations of a few conserved residues. These findings provide further insights into the molecular mechanism for the XA recognition by GEP1 and the activation of the gametogenesis of malaria parasites through GEP1-GCα interaction.

Structural maintenance of chromosomes (SMC) complexes are critical chromatin modulators. In eukaryotes, the cohesin and condensin SMC complexes organize chromatin, while the Smc5/6 complex directly regulates DNA replication and repair. The molecular basis for the distinct functions of Smc5/6 is poorly understood. Here, we report an integrative structural study of the budding yeast Smc5/6 holo-complex using electron microscopy, cross-linking mass spectrometry, and computational modeling. We show that the Smc5/6 complex possesses several unique features, while sharing some architectural characteristics with other SMC complexes. In contrast to arm-folded structures of cohesin and condensin, Smc5 and Smc6 arm regions do not fold back on themselves. Instead, these long filamentous regions interact with subunits uniquely acquired by the Smc5/6 complex, namely the Nse2 SUMO ligase and the Nse5/Nse6 subcomplex, with the latter also serving as a linchpin connecting distal parts of the complex. Our 3.0-Å resolution cryoelectron microscopy structure of the Nse5/Nse6 core further reveals a clasped-hand topology and a dimeric interface important for cell growth. Finally, we provide evidence that Nse5/Nse6 uses its SUMO-binding motifs to contribute to Nse2-mediated sumoylation. Collectively, our integrative study identifies distinct structural features of the Smc5/6 complex and functional cooperation among its coevolved unique subunits.

A systematic parametric study is presented on the modal global linear instability of Mach 6 boundary-layer flow over an inclined cone at a 6° angle of attack under typical wind tunnel conditions. The analysis is performed using the spatial BiGlobal theory. Results reveal two classes of global instabilities in the outboard region away from the leeward plane: high-frequency (hundreds of kHz) second mode instabilities and low-frequency (tens of kHz) crossflow instabilities. In the global eigenvalue spectra of the second mode instability, two distinct branches of significantly unstable modes are identified, namely, an approximately continuous spectrum (branch S) and a few discrete points (branch D). The branch D modes peak at the windward centerline, while branch S modes lie at a certain distance away from the windward meridian. The global stability characteristics of the crossflow instability over a conical configuration are uncovered for the first time. In the global eigenvalue spectra of the crossflow instability, many unstable modes emerge and form a complex pattern, with the most amplified frequency of around 30 kHz. The unstable crossflow modes are mainly distributed on the leeward side and wave angles obviously increase toward the leeward centerline. The peak growth rates are slightly smaller than those of second modes, and yet the most amplified frequency varies rather mildly along the streamwise direction so that they may achieve larger integrated growth rates than second modes do.

Structural maintenance of chromosomes (SMC) complexes are critical chromatin modulators. In eukaryotes, the cohesin and condensin SMC complexes organize chromatin, while the Smc5/6 complex directly regulates DNA replication and repair. The molecular basis for Smc5/6’s distinct functions is currently poorly understood. Here, we report an integrative structural study of the budding yeast Smc5/6 complex using electron microscopy, cross-linking mass spectrometry, and computational modeling. We show that while the complex shares a similar overall organization with other SMC complexes, it possesses several unique features. In contrast to the reported folded-arm structures of cohesin and condensin, our data suggest that Smc5 and Smc6 arm regions do not fold back on themselves. Instead, these long filamentous regions interact with subunits uniquely acquired by the Smc5/6 complex, namely the Nse2 SUMO ligase and the Nse5-Nse6 subcomplex. Further, we show that Nse5-Nse6 subcomplex adopts a novel structure with an extensive dimerization interface and multiple domains contacting other subunits of the Smc5/6 complex. We also provide evidence that the Nse5-Nse6 module uses its SUMO-binding motifs to contribute to Nse2-mediated sumoylation. Collectively, our integrative multi-scale study identifies distinct structural features of the Smc5/6 complex and functional cooperation amongst its co-evolved unique subunits.

In this paper, a method of ball milling and sieving is proposed for recovery of high-grade copper from waste printed circuit boards (WPCBs). The effects of the milling time on the metals grade and recovery of the Cu, Sn and Pb during mechanical treatment were investigated. The results showed that, after 3 cycles of ball milling and sieving, the content of Cu was enriched to 94.72 wt.% from the initial 74.22 wt.% with a high recovery rate of 86.78%. Moreover, the contents of Sn and Pb were enriched to 28.27 wt.% and 18.86 wt.% from 10.13 wt.% and 6.63 wt.% in the by-products, respectively. However, excessive grinding occurred when the milling time was longer than 3 h and led to a sharp decrease in Cu recovery. The X-ray diffraction (XRD) patterns indicated that the metal phases mainly comprised pure Cu, Sn, Pb in the WPCB particles, while a Cu-Sn alloy was formed during the milling process, and the Cu-Sn alloy was also enriched in the tailings. The results presented here establish that ball milling and sieving is an alternative approach to recovering high-grade copper from WPCBs.

The hypersonic boundary-layer receptivity to slow acoustic waves is investigated for the Mach 6 flow over a 5-degree half-angle blunt cone with the nose radius of 5.08 mm. The plane acoustic wave interacts with the bow shock, and generates all types of disturbances behind the shock, which may take various routes to generate the boundary-layer unstable mode. In this paper, two routes of receptivity are investigated in detail. One is through the disturbance in the entropy layer. The other is through the slow acoustic wave transmitted downstream the bow shock, which can excite the boundary-layer mode due to the synchronization mechanism. The results show that, for a low frequency slow acoustic wave, the latter route plays a leading role. The entropy-layer instability wave is able to excite the first mode near the neutral point, but its receptivity efficiency is much lower.

Compared to the traditional Star impeller, the designed impeller (hereinafter termed as the XSR impeller) has the characteristic of pumping which can promote degassing efficiency, and smaller area of the dead region and higher turbulent kinetic energy are obtained within the melt simultaneously. In the range of the discussed immersion depths of impeller (H = 185 mm, 315 mm and 435 mm), both too shallow depth (185 mm) and too deep depth (435 mm) are bad for the distribution of flow field. For the discussed rotational velocities of impeller (V = 390 rpm, 430 rpm, 480 rpm and 550 rpm), as the V increases, the intensity of fluid flow increases accordingly, and the area of lower turbulent kinetic energy reduces gradually. For the XSR impeller, the optimal immersion depth and rotational velocity are 315 mm and 550 rpm, respectively. The experimental data are in well accordance with the simulated results. Under the optimal process parameters, the average volume fraction of voids and inclusions of the A356 melt decreases by 98%. The as-cast A356 alloy with higher cleanliness exhibits an ultimate tensile strength (UTS) of 161 MPa, a yield strength (YS) of 72 MPa and an elongation (EL) of 14%.

Livestock grazing can affect both above- and below-ground communities, however, the effects of grazing intensity on vertical distribution of root traits and their associations with belowground food webs are still unclear. Based on a 5-year grazing intensity experiment (i.e., no grazing, moderate grazing and heavy grazing) in a Tibetan plateau meadow, we investigated how grazing-induced changes in root traits affected soil biota (microbes and nematodes) from the surface (0–10 cm) and subsurface soils (10–20 cm). Our results showed that moderate grazing increased nematode abundance and structure complexity of the soil micro-food webs compared to no and heavy grazing, and predominantly increased herbivores and fungivores regardless of soil layers. Shifts in herbivores and fungivores were mainly driven by root quantity and quality, emphasizing the stronger bottom-up effects on the lower trophic levels of nematodes. Grazing decreased the number of omnivores-predators in the surface soil compared to no grazing, which therefore weakened predation pressure on soil nematodes lower in the trophic structure, including root herbivores, while that effect was far less pronounced in the subsurface soil. Our study demonstrated that changes in root quantity and quality were highly associated with the complexity of the soil micro-food webs under grazing scenarios. These findings warranted the ideas that combined aboveground herbivore-root-soil micro-food webs as an ecological holo is essential for sustainable management of grassland.

In contrast with the conventional remelting recycling of aluminum and its alloy chips, the solid state recycling techniques, which can convert the chips directly into dense bulk materials, have attracted significant attention primarily because it possesses many advantages including lower energy consumption, lower metal loss as well as almost no emissions of harmful gases and solid wasters. In this keynote paper, with a view to the current researches of the solid state recycling techniques based on the severe plastic deformation (SPD) and powder metallurgy (P/M), the characteristics and applications of several typical methods, such as hot extrusion, equal channel angular pressing (ECAP), cyclic extrusion compression (CEC), friction stir extrusion (FSE), high pressure torsion (HPT), screw extrusion and spark plasma sintering (SPS), are introduced. A growing number of researches and literatures suggest that the mechanical properties of solid state recycled specimens are primarily dependent on the chip bonding quality and microstructure of the corresponding bulk materials. Then, the mechanism analysis of consolidation of chips is carried out, and three relevant theoretical modes, characterizing the bonding quality, are also mentioned. Moreover, the factors influencing the density and microstructure of chip-consolidated product are discussed comprehensively. Eventually, recommendations in the improvement of solid state recycling techniques and the future prospects are put forward.

Efficient pre-processing is essential to the mechanical recovery of waste printed circuit boards (WPCBs). In this work, a thermal shock pretreatment was utilized to damage the interface between metals and nonmetals of single-sided copper clad laminates (SSCCLs), which are usually employed as the base material of printed circuit boards (PCBs). The effects of three thermal shock treatment parameters-i.e., peak temperature, holding time, and thermal shock cycle times-on the adhesion strength of SSCCLs were evaluated by orthogonal experiments. Microstructures and peel resistance of SSCCLs before and after thermal shock were characterized by scanning electron microscopy (SEM) and 90° peel test, respectively. Our results showed that the impact of three major factors that influence liberation efficiency was in the sequence of peak temperature > shock cycle times > holding time. Furthermore, the optimal thermal shock level could be achieved when the peak temperature was 300°C with the soaking time of 30 min and three cycle times. In the meantime, the corresponding peel strength of the SSCCLs (0.065 N/mm) was sharply decreased by 94% in comparison with those without thermal shock treatment. The manual dismantling experimental data verified the good feasibility of the optimal thermal shock process, suggesting that the copper foil could be readily dismantled from the substrate by hand after pretreatment, with a successful separation rate of 100% and a peeling efficiency of ~ 30 seconds per piece. Therefore, the optimal thermal shock process could notably improve liberation of metals and nonmetals, which would be helpful for efficient recycling of WPCBs.Implications: The interface between copper foil and laminate dielectric in a PCB can be weakened significantly via efficient thermal shock method. Thus, a good liberation could be achieved after thermal shock. In this work, a manual peeling of copper foil from the SSCCL substrates was achieved efficiently after optimal thermal shock pretreatment, confirming the feasibility of a shorter process of metal recovery from scrap SSCCLs without pulverization. The results will be useful for the pretreatment of recovery of the WPCBs.

Genome maintenance requires coordinated actions of diverse DNA metabolism processes. Scaffolding proteins, such as those containing multiple BRCT domains, can influence these processes by collaborating with numerous partners. The best-studied examples of multi-BRCT scaffolds are the budding yeast Dpb11 and its homologues in other organisms, which regulate DNA replication, repair, and damage checkpoints. Recent studies have shed light on another group of multi-BRCT scaffolds, including Rtt107 in budding yeast and related proteins in other organisms. These proteins also influence several DNA metabolism pathways, though they use strategies unlike those employed by the Dpb11 family of proteins. Yet, at the same time, these 2 classes of multi-BRCT proteins can collaborate under specific situations. This review summarizes recent advances in our understanding of how these multi-BRCT proteins function in distinct manners and how they collaborate, with a focus on Dpb11 and Rtt107.

In the present work, the effect of yttrium (Y) addition (0, 0.15, 0.3, 0.5 and 0.7 wt%) on the microstructure and tensile properties of recycled A356 cast alloys containing 1.0 wt% Fe has been studied systematically. With the addition of Y, despite no transformations of β-Fe (Al 5 FeSi) phases into α-Fe phases, the acicular β-Fe phases were refined remarkably, and the volume fraction of β-Fe phases were decreased evidently. With addition of 0.3 wt% Y, the average length of β-Fe phase decreased from ~78 µm to ~20 µm and the finest β-Fe phases were obtained, in the meantime, the eutectic silicon particles were present in fully modified form, and the secondary dendrite arm spacing (SDAS) reached the lowest value. In addition, it was proposed that according to the microstructural analysis, the Al 2 Si 2 Y intermetallic phases might be responsible for the refinement of the β-Fe phases. With addition of 0.3 wt% Y, the maximum improvement of quality index was achieved, approximately 32% in both as-cast and T6 heat treated alloys, and the corresponding Y-modified alloys in T6 heat treated condition obtained the best tensile properties compared with other experimental alloys, with the corresponding ultimate tensile strength (UTS) and elongation (EL) values being 383.86 MPa and 4.85%, respectively. Furthermore, the tensile properties of 0.3 wt% Y modified recycled Al–7Si–0.3Mg–1.0Fe alloys (T6) exceed the minimum properties standard for ZL101A alloy (JB, T6), approximately 30.12% for UTS value and 61.67% for EL value, suggesting it can be a good candidate for the commercial applications.

The transition of the hypersonic boundary layer and the corresponding control have been extensively interested since the strong engineer background. In the present work, a hypersonic boundary layer over a flat plate of Mach 6 is computed using the high-order finite-difference scheme. The influences of the two-dimensional micro-grooves on the evolution of the second-mode instability wave are investigated. The comparison is carried out between different depths of the micro-groove. The results indicate that the actual control effect does not significantly vary with the depths under the condition with large grooves. The DNS prediction show different results with the theoretical model for the acoustic reflection coefficient. It is suggested that new model should be derived to guide the design and optimize of the parameters of the micro-groove.

The effect of solution time on the aging behavior, corresponding microstructure and mechanical properties of the (Co0.5NiFeCrTi0.5 + SiC)p/7075Al hybrid composite was systematically studied. The hybrid composite was fabricated via squeeze casting, followed by solution treated for 1, 2, 4 and 6 h and subsequent artificial aging. Microstructural analysis revealed that the solution time had a significant effect on the second phase, HEA/Al interface, precipitation behavior and grains in the Co0.5NiFeCrTi0.5 high-entropy alloy (HEA) particle. The amount of the second phase dissolving into the Al matrix initially increased with the increase of solution time. However, there was no obvious change in the amount of the second phase after 4 h because only the insoluble Al7Cu2Fe phase was left in the matrix. The interface between the Al matrix and SiC particles in the hybrid Al matrix composites did not show significant changes with increasing solution time, whereas the interface between the Al matrix and HEA particles gradually grew. The peak-aged time of composites during artificial aging was gradually shortened with the increase of solution time, indicating that longer solution time could accelerate the precipitation kinetics. Composites solution treated for 2 and 4 h displayed the larger supersaturation of Mg and Zn atoms along with a higher density of precipitates than that of the AMC-1h composite at the peak-aged period. The peak-aged composite solution treated for 2 h showed the highest yield strength and tensile strength (551 and 652 MPa), followed by the composite solution treated for 1 h (495 and 608 MPa) and 4 h (469 and 551 MPa). However, the ductility gradually decreased with the increase of solution time due to the interface reaction between the Al matrix and SiC particles. The relationship between the solution time and precipitation behaviors in the vicinity of the SiC/Al and HEA/Al interface of hybrid composites were systematically studied. Our work provides new insights for the development of heat-treatable Al matrix composites reinforced by metallic particles.

Secondary aluminum dross (SAD) is regarded as a solid waste of aluminum recycling process that creates serious environmental and health concerns. However, SAD can also be used as a good source of aluminum, so that utilizing the SAD for the production of valuable products is a promising approach of recycling such waste. In the present work, a novel eco-friendly three-step process was proposed for the synthesis of cryolite (Na3AlF6) from the SAD, and it consisted of (1) water-washing pretreatment of SAD, (2) extraction of Al component via pyro-hydrometallurgy, including low-temperature alkaline smelting, water leaching and purification of leachate in sequence, (3) precipitation of cryolite from the purified NaAlO2 solution using the carbonation method. By analysis of the parameter optimization for each procedure, it was found that the maximum hydrolysis efficiency of aluminum nitride (AlN) in the SAD was around 68.3% accompanied with an extraction efficiency of Al reaching 91.5%. On this basis, the cryolite of high quality was synthesized under the following optimal carbonation conditions: reaction temperature of 75 &deg, C, NaAlO2 concentration of 0.11 mol/L, F/(6Al) molar ratio of 1.10, and 99.99% CO2 gas pressure, and flow rate of 0.2 MPa and 0.5 L/min respectively. The formation of Na3AlF6 phase can be detected by XRD. The morphological feature observed by SEM revealed that the as-synthesized cryolite had a polyhedral shape (~1 &mu, m size) with obvious agglomeration. The chemical composition and ignition loss of the as-synthesized cryolite complied well with the requirements of the Chinese national standard (GB/T 4291-2017).

The dependence of structure and piezoelectric response d33 on individual excess A-site K or Na in K0.5Na0.5NbO3 based lead-free piezoceramics is reported. The coexistence of orthorhombic, tetragonal, and monoclinic phases at room temperature is observed in the investigated 0.94K0.5+xNa0.5NbO3–0.06LiNbO3 and 0.94K0.5Na0.5+yNbO3–0.06LiNbO3 ceramics (x, y = 0–0.025). The weight ratio of three phases, orthorhombic-tetragonal phase transition temperature, and d33 value are highly sensitive to A-site K or Na nonstoichiometry. A-site Na nonstiochiometry plays a dominant role in enhancing the electrical properties of KNN by significantly reducing the weight ratio percentage of monoclinic phase and shifting the orthorhombic-tetragonal phase transition temperature to lower temperatures.

Tetrahymena telomerase holoenzyme subunits p75, p45 and p19 form a subcomplex (7–4–1) peripheral to the catalytic core. We report structures of p45 and p19 and reveal them as the Stn1 and Ten1 subunits of the CST complex, which stimulates telomerase complementary-strand synthesis. 7–4–1 binds telomeric single-stranded DNA, and mutant p19 overexpression causes telomere 3′-overhang elongation. We propose that telomerase-tethered Tetrahymena CST coordinates telomere G-strand and C-strand synthesis.

SLX4 assembles a toolkit of endonucleases SLX1, MUS81 and XPF, which is recruited to telomeres via direct interaction of SLX4 with TRF2. Telomeres present an inherent obstacle for DNA replication and repair due to their high propensity to form branched DNA intermediates. Here we provide novel insight into the mechanism and regulation of the SLX4 complex in telomere preservation. SLX4 associates with telomeres throughout the cell cycle, peaking in late S phase and under genotoxic stress. Disruption of SLX4's interaction with TRF2 or SLX1 and SLX1's nuclease activity independently causes telomere fragility, suggesting a requirement of the SLX4 complex for nucleolytic resolution of branched intermediates during telomere replication. Indeed, the SLX1-SLX4 complex processes a variety of telomeric joint molecules in vitro. The nucleolytic activity of SLX1-SLX4 is negatively regulated by telomeric DNA-binding proteins TRF1 and TRF2 and is suppressed by the RecQ helicase BLM in vitro. In vivo, in the presence of functional BLM, telomeric circle formation and telomere sister chromatid exchange, both arising out of nucleolytic processing of telomeric homologous recombination intermediates, are suppressed. We propose that the SLX4-toolkit is a telomere accessory complex that, in conjunction with other telomere maintenance proteins, ensures unhindered, but regulated telomere maintenance.

6061Al matrix composites reinforced by 7.5 vol.% nanocrystalline CoNiFeAl 0.4 Ti 0.6 Cr 0.5 high-entropy alloy (HEA) particles have been synthesized by powder processing of powder mixture ball milled for 10 h, 20 h and 40 h. Results indicated that the average ultimate tensile strength and fracture strain of the 6061Al-HEA-10 h composite were 378 MPa and 8.4%, better than those of the 6061Al-HEA-20 h composite, which was related to the homogeneous distribution of HEA particles. Specifically, the 6061Al-HEA-40 h composite had the highest ultimate strength and yield strength, and the fracture strain was close to the 6061Al-HEA-20 h composite, related with the formation of fine HEA particle clusters and a heterogeneous grain structure. The strengthening mechanisms for the improved strength of the composites are mainly derived from the Hall–Petch effect and geometrically necessary dislocations.

Boundary-layer transition (BLT) is one of the key problems in developing hypersonic aircrafts. Major aerospace countries all over the world have been heavily supporting relevant researches, and the project funding keeps increasing in recent years. In this paper, wind tunnel experiments, numerical simulations and theoretical analysis are combined to study some hot issues in this area, which include effects of unit Reynolds number, angle of attack and nose bluntness, nonlinear interactions during breakdown, secondary instability of crossflow vortices, etc. Some of our views on understanding hypersonic BLT are summarized. The wind tunnel tests are conducted in the Φ1 m hypersonic wind tunnel of China Aerodynamics Research and Development Center, and the relation between transition location and different unit Reynolds numbers, angles of attack and nose bluntness is obtained. It is well known that hypersonic BLT undergoes an important phenomenon called “nose-bluntness inversal”, but a worldwide accepted reasonable explanation for this phenomenon is still missing. To investigate the “nose-bluntness reversal”, we suggest to consider the influence of front shock waves because free-stream disturbances are changed by shock waves. Meanwhile, we should also consider the following two aspects: blunt-nose receptivity and entropy-layer effect. Some premiliary but encouraging results are presented on these two aspects via direct numerical simulations (DNS) and stablity analysis. During the late stage of transition, a “quiet zone” may appear when the second mode waves reach large amplitude, and this is followed by low-frequency modes. DNS and the dynamic mode decomposition are applied to study this problem. The results indicate that the relation between the second modes and the low-frequency modes is possibly mode transformation. In the end of this paper, a newly discovered secondary unstable mode of saturated crossflow vortices is introduced. This mode has the same level of growth rate as Z mode, but is related to the wall-normal shear stress, thus it is named Y mode.

Menin is a tumour suppressor protein whose loss or inactivation causes multiple endocrine neoplasia 1 (MEN1), a hereditary autosomal dominant tumour syndrome that is characterized by tumorigenesis in multiple endocrine organs. Menin interacts with many proteins and is involved in a variety of cellular processes. Menin binds the JUN family transcription factor JUND and inhibits its transcriptional activity. Several MEN1 missense mutations disrupt the menin-JUND interaction, suggesting a correlation between the tumour-suppressor function of menin and its suppression of JUND-activated transcription. Menin also interacts with mixed lineage leukaemia protein 1 (MLL1), a histone H3 lysine 4 methyltransferase, and functions as an oncogenic cofactor to upregulate gene transcription and promote MLL1-fusion-protein-induced leukaemogenesis. A recent report on the tethering of MLL1 to chromatin binding factor lens epithelium-derived growth factor (LEDGF) by menin indicates that menin is a molecular adaptor coordinating the functions of multiple proteins. Despite its importance, how menin interacts with many distinct partners and regulates their functions remains poorly understood. Here we present the crystal structures of human menin in its free form and in complexes with MLL1 or with JUND, or with an MLL1-LEDGF heterodimer. These structures show that menin contains a deep pocket that binds short peptides of MLL1 or JUND in the same manner, but that it can have opposite effects on transcription. The menin-JUND interaction blocks JUN N-terminal kinase (JNK)-mediated JUND phosphorylation and suppresses JUND-induced transcription. In contrast, menin promotes gene transcription by binding the transcription activator MLL1 through the peptide pocket while still interacting with the chromatin-anchoring protein LEDGF at a distinct surface formed by both menin and MLL1.

Hypersonic boundary-layer transition (BLT) is affected by multifarious factors, some of which cannot be simulated in ground wind tunnels, which makes the BLT data of wind tunnel experiments are usually different to that of flight experiments. In order to convert BLT data from wind tunnels to real flight cases, and to improve BLT prediction accuracy, a blunt cone model with zero angle-of-attack and 7° semi-cone angle is selected to contrastive analysis the boundary-layer stability and transition between wind tunnels and flights by using linear stability theory and eN method, based on the data set of our MF-1 flight test and hypersonic wind tunnel experiments, as well as an abroad flight test and wind tunnel experiments. The results show that the difference of stability and transition between wind tunnels and flights is essential. The wall temperature ratio in flights is smaller than that in wind tunnels, which leads to the second mode frequency in flight tests are greater than that of wind tunnel experiments. Two empirical formulas are developed to compute the most unstable frequency of the second mode. These formulas are shown suitable for both flight conditions and wind tunnel conditions. It is also shown that the N value ( N T) at the start of BLT is greatly affected by the nose Reynolds number. The larger the nose Reynolds number, the smaller the N T value. When the nose-tip bluntness is large enough, the BLT occurs even without boundary-layer mode instability. The front bow shock waves of blunt bodies will induce entropy layers, and the bluntness will affect the location (swallow point) where the entropy layers merge into the boundary layers. The relative location of transition point and swallow point is shown in good correlation with the N T, and the trend is similar for both wind tunnels and flights. A correlation between the transition-swallow relative location and the N T is developed by the least square method. This correlation is expected to conveniently predict hypersonic BLT of similar conditions.

The epigenetic silencing of tumor suppressor genes is a crucial event during carcinogenesis and metastasis. Here, in a human genome-wide survey, we identified scavenger receptor class A, member 5 (SCARA5) as a candidate tumor suppressor gene located on chromosome 8p. We found that SCARA5 expression was frequently downregulated as a result of promoter hypermethylation and allelic imbalance and was associated with vascular invasion in human hepatocellular carcinoma (HCC). Furthermore, SCARA5 knockdown via RNAi markedly enhanced HCC cell growth in vitro, colony formation in soft agar, and invasiveness, tumorigenicity, and lung metastasis in vivo. By contrast, SCARA5 overexpression suppressed these malignant behaviors. Interestingly, SCARA5 was found to physically associate with focal adhesion kinase (FAK) and inhibit the tyrosine phosphorylation cascade of the FAK-Src-Cas signaling pathway. Conversely, silencing SCARA5 stimulated the signaling pathway via increased phosphorylation of certain tyrosine residues of FAK, Src, and p130Cas; it was also associated with activation of MMP9, a tumor metastasis–associated enzyme. Taken together, these data suggest that the plasma membrane protein SCARA5 can contribute to HCC tumorigenesis and metastasis via activation of the FAK signaling pathway.

This study reported that all three human BolA proteins (hBolA1, hBolA2, and hBolA3) are novel non-classical secreted proteins identified with bioinformatics and molecular biology experiments. The three BolA fusion proteins with c-Myc tag could be secreted into the culture medium of the transfected Cos-7 cells, although they could not be colocalized with Golgi apparatus. And the secretion of three BolA proteins could not be inhibited after BFA treatment. Furthermore, the secretion was not dependent on its predicted signal peptide. All the experiment results suggested that the secretion was a non-classical export. Phylogenetic analysis showed that the human BolAs belong to three different groups with functional divergence of BolA subfamily, where the different helix-turn-helix motif among hBolA1, hBolA2, and hBolA3 could be responsible for their functional divergence. Our data provided a basis for functional studies of BolA protein family.