This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analog...This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.展开更多
In this paper, we investigate the stator wake variability along the axial direction under different rotating speeds and mass flow conditions, in the terms of wake-core position, wake depth, wake width and wake velocit...In this paper, we investigate the stator wake variability along the axial direction under different rotating speeds and mass flow conditions, in the terms of wake-core position, wake depth, wake width and wake velocity gradient. Experimental study is carried out in a single stage axial compressor by using Hot-wire Anemometer (HWA). Simultaneously, the numerical calculation is brought out in the same experiment rig. Firstly, we analyze the time-averaged velocity and radial vorticity at different axial positions, and explore the wake variability along the axial direction. Then, we present the effects of operation conditions on the wake-core position, and find out the inlet Mach number and incident angle are both the key influence factors of the wake-core position. Finally, we summarize four preliminary conclusions of the wake variability.展开更多
Basalt fiber(BF)is widely applied in the construction industry to improve the mechanical properties of construction materials.Recent studies show that BF has the potential to further enhance its performance via a crys...Basalt fiber(BF)is widely applied in the construction industry to improve the mechanical properties of construction materials.Recent studies show that BF has the potential to further enhance its performance via a crystallization approach.In this work,the glass-ceramic basalt fibers(GCBFs)were prepared through nucleation and crystallization treatments according to the crystallization kinetics calculations.Results from XRD and SEM show that GCBFs have main crystalline phases of Diopside and Augite reach crystallinity of around 46%±10%.In particular,the GCBFs sample with the largest mean crystal size maintains the lowest tensile strength of~197 MPa(compared with the pristine BFs of~737 MPa).Moreover,the weight loss and ion dissolution of GCBFs were explored in seawater environments and it was investigated that,GCBFs have better anti-seawater corrosion than the pristine BFs and have the potential to apply in the marine industry.展开更多
The inherent unsteady pressure fluctuations on the rotating blade suction surface of an axial compressor were experimentally measured by directly mounting five high response miniature pressure transducers into the rot...The inherent unsteady pressure fluctuations on the rotating blade suction surface of an axial compressor were experimentally measured by directly mounting five high response miniature pressure transducers into the rotor blade along a streamline at 50% span respectively. The results show that the unsteady pressure fluctuations of rotor blade surface could be measured successfully by this means. The relations about the period, altitude of unsteady pressure with rotating speed, the discipline of pressure fluctuation along the streamwise direction were obtained.展开更多
Because of its high mobility and difficult capture,gaseous arsenic pollution control has become the focus of arsenic pollution control.It mainly exists in the form of highly toxic As_(2)O_(3)in the flue gas.Therefore,...Because of its high mobility and difficult capture,gaseous arsenic pollution control has become the focus of arsenic pollution control.It mainly exists in the form of highly toxic As_(2)O_(3)in the flue gas.Therefore,removing gaseous As_(2)O_(3)from flue gas is of great practical significance for arsenic pollution control.Stabilizing gaseous As_(2)O_(3)on the surface of adsorbents by physical or chemical adsorption is an effective way to reduce the content of arsenic in the flue gas and alleviate arsenic pollution.Over the past few decades,various adsorbents have been developed to capture gaseous As_(2)O_(3)in the flue gas,and their adsorption mechanisms have been studied in detail.Thus,it is necessary to review the strategies of arsenic removal from flue gas by adsorption,which can inspire further research.Based on summarizing the morphological distribution of gaseous As_(2)O_(3)in the flue gas,this review further summarizes the removal of gaseous As_(2)O_(3)by several adsorbents and the effect of temperature and the main components of the flue gas on arsenic adsorption.In addition,the mechanism of arsenic removal based on adsorption in the flue gas is discussed in depth through theoretical calculations,which is the particular focus of this review.Finally,prospects based on the present research state of arsenic removal by adsorption are proposed to provide ideas for developing effective and stable adsorbents for arsenic removal from flue gas.展开更多
Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed.The surface properties and structure of birnessite change with the changes in external environmental condition...Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed.The surface properties and structure of birnessite change with the changes in external environmental conditions,which also affects the fate of heavy metals.Clarifying the effect and mechanism of the birnessite phase transition process on heavy metals is the key to taking effective measures to prevent and control heavy metal pollution.Therefore,the four transformation pathways of birnessite are summarized first in this review.Second,the relationship between transformation pathways and environmental conditions is proposed.These relevant environmental conditions include abiotic(e.g.,co-existing ions,pH,oxygen pressure,temperature,electric field,light,aging,pressure)and biotic factors(e.g.,microorganisms,biomolecules).The phase transformation is achieved by the key intermediate of Mn(Ⅲ)through interlayer-condensation,folding,neutralizationdisproportionation,and dissolution-recrystallization mechanisms.The AOS(average oxidation state)of Mn and interlayer spacing are closely correlated with the phase transformation of birnessite.Last but not least,the mechanisms of heavy metals immobilization in the transformation process of birnessite are summed up.They involve isomorphous substitution,redox,complexation,hydration/dehydration,etc.The transformation of birnessite and its implication on heavy metals will be helpful for understanding and predicting the behavior of heavy metals and the crucial phase of manganese oxides/hydroxides in natural and engineered environments.展开更多
Dust particles emitted from smelters can be hazardous to ecosystems and humans,as they are often enriched in metallic compounds.Here,we combined multi-method mineralogical analysis with a sophisticated size sorting ap...Dust particles emitted from smelters can be hazardous to ecosystems and humans,as they are often enriched in metallic compounds.Here,we combined multi-method mineralogical analysis with a sophisticated size sorting approach for copper smelting dust to study the nanosize-effect on heavy metal distribution,which has hitherto been underestimated.Three types of dust were collected from a copper flash smelter and then size-sorted using a Dekati low-pressure impactor.Results showed that all three samples could easily sort out nanoscale dust particles(<1μm,grades 10–2)and even those smaller than 100 nm(grades 5–2).Especially for electrostatic precipitators dust,the mass fraction of nanoscale dust(<1μm)could reach 10.71%.The presence of heavy metals(Pb,Zn,Cu,and As)and their mineral species in dust was examined at various particle sizes.It was discovered that different heavy metals are enriched on nanoparticles in specific sizes.In micron-sized particles,heavy metals are generally found in discrete phases(e.g.,CuSO_(4),PbSO_(4),and As_(2)O_(3)).In nanoscale particles,the dominant phase is Fe_(3)O_(4),while heavy metals are mostly found in lattice substitution(e.g.,CuFe_(2)O_(4)and ZnFe_(2)O_(4)).Two distinct nano-dust morphologies were found:One with irregular mesh or chain structures consisting of particles of a few nanometers,and the other with polygonal crystals in larger sizes of hundreds of nanometers.The enrichment of heavy metals in the latter morphology is more pronounced,possibly because lattice substitution of heavy metals is more likely to occur when polycrystalline particles are formed.展开更多
The clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated gene(Cas) system is continually optimized to achieve the most efficient gene editing effect. The Cas12i^(Max), a Cas12i variant, ...The clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated gene(Cas) system is continually optimized to achieve the most efficient gene editing effect. The Cas12i^(Max), a Cas12i variant, exhibits powerful DNA editing activity and enriches the gene editing toolbox. However, the application of Cas12i^(Max)in large domestic animals has not yet been reported. To verify the efficiency and feasibility of multiple gene editing in large animals, we generated porcine fibroblasts with simultaneous knockouts of IGF2, ANPEP, CD163,and MSTN via Cas12i^(Max)in one step. Phenotypically stable pigs were created through somatic cell nuclear transfer technology. They exhibited improved growth performance and muscle quality. Furthermore, we simultaneously edited three genes in bovine fibroblasts. A knockout of MSTN and PRNP was created and the amino acid Q-G in CD18 was precisely substituted. Meanwhile, no off-target phenomenon was observed by sum-type analysis or off-target detection. These results verified the effectiveness of Cas12i^(Max)for gene editing in livestock animals and demonstrated the potential application of Cas12i^(Max)in the field of animal trait improvement for agricultural production.展开更多
High-performance terahertz(THz)devices with reconfigurable features are highly desirable in many promising THz applications.However,most of the existing reconfigurable THz elements are still limited to volatile respon...High-performance terahertz(THz)devices with reconfigurable features are highly desirable in many promising THz applications.However,most of the existing reconfigurable THz elements are still limited to volatile responses,single functionality,and time-consuming multistep manufacturing procedures.In this paper,we report a lithography-free approach to create reconfigurable and nonvolatile THz components by exploring the reversible,nonvolatile,and continuous THz modulation capability of the phase change material Ge_(2)Sb_(2)Te_(5).As a proof of concept,THz gratings with significant Rayleigh anomalies and diffraction as well as ultrathin THz flat lenses with subwavelength and ultra-broadband focusing capabilities are designed and fabricated on ultrathin Ge_(2)Sb_(2)Te_(5)films using the presented photo-imprint strategy.Moreover,such a method can also be adopted to create more complex THz devices,such as Pancharatnam–Berry phase metasurfaces and grayscale holographic plates.With these findings,the proposed method will provide a promising solution to realize reconfigurable and nonvolatile THz elements.展开更多
Millions of people in poor areas are still under the threat of fluoride contamination.How to effectively separate fluorine in water is an important step to reduce the ecological risk.In this paper,we performed a syste...Millions of people in poor areas are still under the threat of fluoride contamination.How to effectively separate fluorine in water is an important step to reduce the ecological risk.In this paper,we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl-and MgAl-LDHs.The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination,because of the better electronic structure.After the defluorination,the LiAl-LDHs with adsorbed-F–were also more stable than the MgAl-LDHs.In addition,the existence of coordination covalent bond for the adsorbed-F–attached to the LiAl-LDHs was confirmed.This is an important reason for the high defluorination efficiency by the LiAl-LDHs.In addition,a series of weak interaction,including hydrogen bond and van der Waals interaction were also observed.Finally,a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal method.The results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g,could be effectively defluorinated in water.Notably,it surpasses most materials and has potential applications.展开更多
Dear Editor,Infection with the novel coronavirus(SARS-CoV-2,which is the virus responsible for the coronavirus disease 2019(COVID-19))was first reported in Wuhan,China on December 31,2019.The outbreak of COVID-19 rema...Dear Editor,Infection with the novel coronavirus(SARS-CoV-2,which is the virus responsible for the coronavirus disease 2019(COVID-19))was first reported in Wuhan,China on December 31,2019.The outbreak of COVID-19 remains ongoing and was linked to more than 80,000 infected patients and more than 3,000 deaths in China as of March 7,2020(Holshue et al.,2020).展开更多
Broadband light sources emitting in the terahertz spectral range are highly desired for applications such as noninvasive imaging and spectroscopy.Conventionally,THz pulses are generated by optical rectification in bul...Broadband light sources emitting in the terahertz spectral range are highly desired for applications such as noninvasive imaging and spectroscopy.Conventionally,THz pulses are generated by optical rectification in bulk nonlinear crystals with millimetre thickness,with the bandwidth limited by the phase-matching condition.Here we demonstrate broadband THz emission via surface optical rectification from a simple,commercially available 19nmthick indium tin oxide(ITO)thin film.We show an enhancement of the generated THz signal when the pump laser is tuned around the epsilon-near-zero(ENZ)region of ITO due to the pump laser field enhancement associated with the ENZ effect.The bandwidth of the THz signal generated from the ITO film can be over 3 THz,unrestricted by the phasematching condition.This work offers a new possibility for broadband THz generation in a subwavelength thin film made of an ENZ material,with emerging physics not found in existing nonlinear crystals.展开更多
Metasurfaces,especially tunable ones,have played a major role in controlling the amplitude,phase,and polarization of electromagnetic waves and attracted growing interest,with a view toward a new generation of miniatur...Metasurfaces,especially tunable ones,have played a major role in controlling the amplitude,phase,and polarization of electromagnetic waves and attracted growing interest,with a view toward a new generation of miniaturized devices.However,to date,most existing reconfigurable devices are bounded in volatile nature with sustained external energy to maintain and single functionality,which restrict their further applications.Here,we demonstrate for the first time,to our knowledge,nonvolatile,reconfigurable,and dynamic Janus metasurfaces by incorporating phase-change material Ge_(2)Se_(2)Te_(5)(GST)in the terahertz(THz)regime.First,we experimentally show the reversible switching characteristic of GST on large areas by applying a single nanosecond laser pulse,which exhibits excellent contrast of THz properties in both states.Then,we present a multiplex metasurface scheme.In each metasurface,three sets of structures are adopted,in which two sets integrate GST.The effective structures can be reversely modulated by the amorphization and crystallization of GST.As a proof of concept,the dynamic beam splitter,bifocal metalens,dual-mode focusing optical vortex generators,and switchable metalens/focusing optical vortex generators are designed,fabricated,and experimentally characterized,and can be switched reversibly and repeatedly with the help of optical and thermal stimuli.Our scheme will pave the way toward the development of multifunctional and compact THz devices and may find use for applications in THz imaging,sensing,and communications.展开更多
Quantum teleportation is a key primitive across a number of quantum information tasks and represents a fundamental ingredient for many quantum technologies. Channel capacity, other than the fidelity, becomes another f...Quantum teleportation is a key primitive across a number of quantum information tasks and represents a fundamental ingredient for many quantum technologies. Channel capacity, other than the fidelity, becomes another focus of quantum communication. Here, we present a 5-channel multiplexing continuous-variable quantum teleportation protocol in the optical frequency comb system, exploiting five-order entangled sideband modes.Because of the resonant electro-optical modulation(EOM) that is specifically designed, the fidelities of five channels are greater than 0.78, which are superior to the no-cloning limit of 2∕3. This work provides a feasible scheme for implementing efficient quantum information processing.展开更多
Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few s...Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few studies have examined the exact interaction of Pb with jarosite and the dissolution behavior of each phase. In the present work, we demonstrate that Pb mainly interacts with jarosite in four modes, namely incorporation, occlusion,physically mixing, and chemically mixing. For comparison, the four modes of Pb-bearing natrojarosite were synthesized and characterized separately. Batch dissolution experiments were undertaken on these synthetic Pb-bearing natrojarosites under pH_(2) to simulate the AMD environments. The introduction of Pb decreases the final Fe releasing efficiency of jarosite-type compounds from 18.18% to 3.45%-5.01%, showing a remarkable inhibition of their dissolution. For Pb releasing behavior, PbSO_(4) dissolves in preference to Pb-substituted natrojarosite, i.e.,(Na, Pb)-jarosite, which primarily results in the sharp increase of Pb releasing concentration(> 40 mg/L). PbSO_(4) occlusion by jarosite-type compounds can significantly reduce the release of Pb. The results of this study could provide useful information regarding Fe and Pb cycling in acidic natural and engineered environments.展开更多
Metasurfaces consisting of artificial subwavelength structure arrays have shown unprecedented ability to manipulate the phase,amplitude,and polarization of light.Separate and complete control over different spin state...Metasurfaces consisting of artificial subwavelength structure arrays have shown unprecedented ability to manipulate the phase,amplitude,and polarization of light.Separate and complete control over different spin states,namely the orthogonal circular polarizations,has proven more challenging as compared to the control over orthogonal linear polarizations.Here,we present and experimentally demonstrate several spin-dependent wavefront control metasurfaces in the terahertz regime using all-silicon dielectric structures.Such spin-dependent allsilicon metasurfaces are easy to fabricate and have potential applications in spin-involved ultracompact and miniaturized terahertz optical systems as well as terahertz communication systems.展开更多
To meet the challenges posed by global arsenic water contamination, the Mg Al Mn-LDHs with extraordinary efficiency of arsenate removal was developed. In order to clarify the enhancement effect of the doped-Mn on the ...To meet the challenges posed by global arsenic water contamination, the Mg Al Mn-LDHs with extraordinary efficiency of arsenate removal was developed. In order to clarify the enhancement effect of the doped-Mn on the arsenate removal performance of the LDHs, the cluster models of the Mg Al Mn-LDHs and Mg Al-LDHs were established and calculated by using density functional theory(DFT). The results shown that the doped-Mn can significantly change the electronic structure of the LDHs and improve its chemical activity. Compared with the Mg Al-LDHs that without the doped-Mn, the HOMO-LUMO gap was smaller after doping. In addition, the-OH and Al on the laminates were also activated to improve the adsorption property of the LDHs. Besides, the doped-Mn existed as a novel active site. On the other hand, the Mg Al Mn-LDHs with the doped-Mn, the increased of the binding energy, as well as the decreased of the ion exchange energy of interlayer Cl^(-), making the ability to arsenate removal had been considerably elevated than the Mg Al-LDHs. Furthermore, there is an obvious coordination covalent bond between arsenate and the laminates of the Mg Al MnLDHs that with the doped-Mn.展开更多
基金supported by the Young Scientist Project of National Key Research and Development Program of China(2021YFC2900600)the National Natural Science Foundation of China(52074166)Shandong Province(ZR2021YQ38).
文摘This study aims to investigate the benefcial efects of surface retaining elements (SREs) on the mechanical behaviors of bolted rock and roadway stability. 3D printing (3DP) technology is utilized to create rock analogue prismatic specimens for conducting this investigation. Uniaxial compression tests with acoustic emission (AE) and digital image correlation techniques have been conducted on 3DP specimens bolted with diferent SREs. The results demonstrate that the strength and modulus of elasticity of the bolted specimens show a positive correlation with the area of the SRE;the AE characteristics of the bolted specimens are higher than those of the unbolted specimen, but they decrease with an increase in SRE area, thus further improving the integrity of the bolted specimens. The reinforcement efect of SREs on the surrounding rock of roadways is further analyzed using numerical modelling and feld test. The results provide a better understanding of the role of SREs in rock bolting and the optimization of rock bolting design. Furthermore, they verify the feasibility of 3DP for rock analogues in rock mechanics tests.
文摘In this paper, we investigate the stator wake variability along the axial direction under different rotating speeds and mass flow conditions, in the terms of wake-core position, wake depth, wake width and wake velocity gradient. Experimental study is carried out in a single stage axial compressor by using Hot-wire Anemometer (HWA). Simultaneously, the numerical calculation is brought out in the same experiment rig. Firstly, we analyze the time-averaged velocity and radial vorticity at different axial positions, and explore the wake variability along the axial direction. Then, we present the effects of operation conditions on the wake-core position, and find out the inlet Mach number and incident angle are both the key influence factors of the wake-core position. Finally, we summarize four preliminary conclusions of the wake variability.
基金Sponsored by the National Key R&D Program of China(Grant No.2021YFB3701600)the National Natural Science Foundation of China(Grant No.51873032)+2 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.223201900003, 2232021D-04, 2232021D-07, 2232021G-07)the Key Research and Development Program of Shandong Province(Grant No.2019JZZY010308)the Open Fund of the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology)。
文摘Basalt fiber(BF)is widely applied in the construction industry to improve the mechanical properties of construction materials.Recent studies show that BF has the potential to further enhance its performance via a crystallization approach.In this work,the glass-ceramic basalt fibers(GCBFs)were prepared through nucleation and crystallization treatments according to the crystallization kinetics calculations.Results from XRD and SEM show that GCBFs have main crystalline phases of Diopside and Augite reach crystallinity of around 46%±10%.In particular,the GCBFs sample with the largest mean crystal size maintains the lowest tensile strength of~197 MPa(compared with the pristine BFs of~737 MPa).Moreover,the weight loss and ion dissolution of GCBFs were explored in seawater environments and it was investigated that,GCBFs have better anti-seawater corrosion than the pristine BFs and have the potential to apply in the marine industry.
文摘The inherent unsteady pressure fluctuations on the rotating blade suction surface of an axial compressor were experimentally measured by directly mounting five high response miniature pressure transducers into the rotor blade along a streamline at 50% span respectively. The results show that the unsteady pressure fluctuations of rotor blade surface could be measured successfully by this means. The relations about the period, altitude of unsteady pressure with rotating speed, the discipline of pressure fluctuation along the streamwise direction were obtained.
基金supported by the National Science Fund for Excellent Young Scholars of China (No.52022111)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No.52121004)+1 种基金the Hunan High Tech Industry Science and Technology Innovation Leading Plan Project (No.2020SK2006)the Huxiang Youth Talent Support Program (No.2020RC3012)。
文摘Because of its high mobility and difficult capture,gaseous arsenic pollution control has become the focus of arsenic pollution control.It mainly exists in the form of highly toxic As_(2)O_(3)in the flue gas.Therefore,removing gaseous As_(2)O_(3)from flue gas is of great practical significance for arsenic pollution control.Stabilizing gaseous As_(2)O_(3)on the surface of adsorbents by physical or chemical adsorption is an effective way to reduce the content of arsenic in the flue gas and alleviate arsenic pollution.Over the past few decades,various adsorbents have been developed to capture gaseous As_(2)O_(3)in the flue gas,and their adsorption mechanisms have been studied in detail.Thus,it is necessary to review the strategies of arsenic removal from flue gas by adsorption,which can inspire further research.Based on summarizing the morphological distribution of gaseous As_(2)O_(3)in the flue gas,this review further summarizes the removal of gaseous As_(2)O_(3)by several adsorbents and the effect of temperature and the main components of the flue gas on arsenic adsorption.In addition,the mechanism of arsenic removal based on adsorption in the flue gas is discussed in depth through theoretical calculations,which is the particular focus of this review.Finally,prospects based on the present research state of arsenic removal by adsorption are proposed to provide ideas for developing effective and stable adsorbents for arsenic removal from flue gas.
基金supported by the National Natural Science Foundation of China(Nos.51974379,52274414)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+2 种基金the Project of National Science Fund for Excellent Young Scholars of China(No.52022111)the National Key R&D Program of China(No.2022YFD1700101)the Huxiang Youth Talent Support Program(No.2020RC3012)。
文摘Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed.The surface properties and structure of birnessite change with the changes in external environmental conditions,which also affects the fate of heavy metals.Clarifying the effect and mechanism of the birnessite phase transition process on heavy metals is the key to taking effective measures to prevent and control heavy metal pollution.Therefore,the four transformation pathways of birnessite are summarized first in this review.Second,the relationship between transformation pathways and environmental conditions is proposed.These relevant environmental conditions include abiotic(e.g.,co-existing ions,pH,oxygen pressure,temperature,electric field,light,aging,pressure)and biotic factors(e.g.,microorganisms,biomolecules).The phase transformation is achieved by the key intermediate of Mn(Ⅲ)through interlayer-condensation,folding,neutralizationdisproportionation,and dissolution-recrystallization mechanisms.The AOS(average oxidation state)of Mn and interlayer spacing are closely correlated with the phase transformation of birnessite.Last but not least,the mechanisms of heavy metals immobilization in the transformation process of birnessite are summed up.They involve isomorphous substitution,redox,complexation,hydration/dehydration,etc.The transformation of birnessite and its implication on heavy metals will be helpful for understanding and predicting the behavior of heavy metals and the crucial phase of manganese oxides/hydroxides in natural and engineered environments.
基金supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)National Natural Science Foundation of China(Nos.22276218 and 52022111)+1 种基金Major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)Science and Technology Innovation Program of Hunan Province(No.2021RC3013).
文摘Dust particles emitted from smelters can be hazardous to ecosystems and humans,as they are often enriched in metallic compounds.Here,we combined multi-method mineralogical analysis with a sophisticated size sorting approach for copper smelting dust to study the nanosize-effect on heavy metal distribution,which has hitherto been underestimated.Three types of dust were collected from a copper flash smelter and then size-sorted using a Dekati low-pressure impactor.Results showed that all three samples could easily sort out nanoscale dust particles(<1μm,grades 10–2)and even those smaller than 100 nm(grades 5–2).Especially for electrostatic precipitators dust,the mass fraction of nanoscale dust(<1μm)could reach 10.71%.The presence of heavy metals(Pb,Zn,Cu,and As)and their mineral species in dust was examined at various particle sizes.It was discovered that different heavy metals are enriched on nanoparticles in specific sizes.In micron-sized particles,heavy metals are generally found in discrete phases(e.g.,CuSO_(4),PbSO_(4),and As_(2)O_(3)).In nanoscale particles,the dominant phase is Fe_(3)O_(4),while heavy metals are mostly found in lattice substitution(e.g.,CuFe_(2)O_(4)and ZnFe_(2)O_(4)).Two distinct nano-dust morphologies were found:One with irregular mesh or chain structures consisting of particles of a few nanometers,and the other with polygonal crystals in larger sizes of hundreds of nanometers.The enrichment of heavy metals in the latter morphology is more pronounced,possibly because lattice substitution of heavy metals is more likely to occur when polycrystalline particles are formed.
基金supported by the National Key Research and Development Program of China(2018YFE0201100,2021YFA0805905,2021YFA0805701,2022YFA1103101)the National Natural Science Foundation of China(32102549)+3 种基金the National Key R&D Program of Ningxia(2021BEF02023)the China Agriculture Research System of MOF and MARA(CARS-36)the Agricultural Science and Technology Innovation Program(ASTIP-IAS06)the project from The Xinjiang Production and Construction Corps and Foundation of State Key Laboratory for Sheep Genetic Improvement and Healthy Production(2021ZD04)。
文摘The clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated gene(Cas) system is continually optimized to achieve the most efficient gene editing effect. The Cas12i^(Max), a Cas12i variant, exhibits powerful DNA editing activity and enriches the gene editing toolbox. However, the application of Cas12i^(Max)in large domestic animals has not yet been reported. To verify the efficiency and feasibility of multiple gene editing in large animals, we generated porcine fibroblasts with simultaneous knockouts of IGF2, ANPEP, CD163,and MSTN via Cas12i^(Max)in one step. Phenotypically stable pigs were created through somatic cell nuclear transfer technology. They exhibited improved growth performance and muscle quality. Furthermore, we simultaneously edited three genes in bovine fibroblasts. A knockout of MSTN and PRNP was created and the amino acid Q-G in CD18 was precisely substituted. Meanwhile, no off-target phenomenon was observed by sum-type analysis or off-target detection. These results verified the effectiveness of Cas12i^(Max)for gene editing in livestock animals and demonstrated the potential application of Cas12i^(Max)in the field of animal trait improvement for agricultural production.
基金Key Fund of Shenzhen Natural Science Foundation(JCYJ20200109150212515)Tianjin Municipal Fund for Distinguished Young Scholars(20JCJQJC00190)+1 种基金National Natural Science Foundation of China(62235013)National Key Research and Development Program of China(2017YFA0701004,2019YFA0709100,2020YFA0714504)。
文摘High-performance terahertz(THz)devices with reconfigurable features are highly desirable in many promising THz applications.However,most of the existing reconfigurable THz elements are still limited to volatile responses,single functionality,and time-consuming multistep manufacturing procedures.In this paper,we report a lithography-free approach to create reconfigurable and nonvolatile THz components by exploring the reversible,nonvolatile,and continuous THz modulation capability of the phase change material Ge_(2)Sb_(2)Te_(5).As a proof of concept,THz gratings with significant Rayleigh anomalies and diffraction as well as ultrathin THz flat lenses with subwavelength and ultra-broadband focusing capabilities are designed and fabricated on ultrathin Ge_(2)Sb_(2)Te_(5)films using the presented photo-imprint strategy.Moreover,such a method can also be adopted to create more complex THz devices,such as Pancharatnam–Berry phase metasurfaces and grayscale holographic plates.With these findings,the proposed method will provide a promising solution to realize reconfigurable and nonvolatile THz elements.
基金supported by the National Science Fund for Distinguished Young Scholars (No.52022111)the Natural Science Foundation of China (No.51974379)the Scientific and Technological Innovation Program of Hunan Province,Huxiang Youth Talent Project (No.2020RC_(3)012)。
文摘Millions of people in poor areas are still under the threat of fluoride contamination.How to effectively separate fluorine in water is an important step to reduce the ecological risk.In this paper,we performed a systematic DFT calculation focused on the defluorination behavior between the LiAl-and MgAl-LDHs.The results indicated that the LiAl-LDHs exhibited high chemical activity before the defluorination,because of the better electronic structure.After the defluorination,the LiAl-LDHs with adsorbed-F–were also more stable than the MgAl-LDHs.In addition,the existence of coordination covalent bond for the adsorbed-F–attached to the LiAl-LDHs was confirmed.This is an important reason for the high defluorination efficiency by the LiAl-LDHs.In addition,a series of weak interaction,including hydrogen bond and van der Waals interaction were also observed.Finally,a LiAl-LDHs with excellent fluoride removal properties were synthesized well by simple hydrothermal method.The results showed that our synthesized LiAl-LDHs with the capacity of 156.09 mg/g,could be effectively defluorinated in water.Notably,it surpasses most materials and has potential applications.
基金supported by the grants from Sichuan Science and Technology Program(2020YFS0014 and 2020YFS0558)the Chinese Academy of Medical Sciences(2019-I2M-5032)Technology&Science&Technology Bureau of Chengdu(2020YF05-00060-SN and 2020-YF05-00075-SN)。
文摘Dear Editor,Infection with the novel coronavirus(SARS-CoV-2,which is the virus responsible for the coronavirus disease 2019(COVID-19))was first reported in Wuhan,China on December 31,2019.The outbreak of COVID-19 remains ongoing and was linked to more than 80,000 infected patients and more than 3,000 deaths in China as of March 7,2020(Holshue et al.,2020).
基金This work was supported by the National Key Research and Development Program of China(Grant number 2017YFA0701004)the National Natural Science Foundation of China(Grant numbers 61975251,61875150,61735012,and 11774288).
文摘Broadband light sources emitting in the terahertz spectral range are highly desired for applications such as noninvasive imaging and spectroscopy.Conventionally,THz pulses are generated by optical rectification in bulk nonlinear crystals with millimetre thickness,with the bandwidth limited by the phase-matching condition.Here we demonstrate broadband THz emission via surface optical rectification from a simple,commercially available 19nmthick indium tin oxide(ITO)thin film.We show an enhancement of the generated THz signal when the pump laser is tuned around the epsilon-near-zero(ENZ)region of ITO due to the pump laser field enhancement associated with the ENZ effect.The bandwidth of the THz signal generated from the ITO film can be over 3 THz,unrestricted by the phasematching condition.This work offers a new possibility for broadband THz generation in a subwavelength thin film made of an ENZ material,with emerging physics not found in existing nonlinear crystals.
基金National Key Research and Development Program of China(2017YFA0701004,2019YFA0709100,2020YFA0714504)Tianjin Municipal Fund for Distinguished Young Scholars(20JCJQJC00190)Key Fund of Shenzhen Natural Science Foundation(JCYJ20200109150212515)。
文摘Metasurfaces,especially tunable ones,have played a major role in controlling the amplitude,phase,and polarization of electromagnetic waves and attracted growing interest,with a view toward a new generation of miniaturized devices.However,to date,most existing reconfigurable devices are bounded in volatile nature with sustained external energy to maintain and single functionality,which restrict their further applications.Here,we demonstrate for the first time,to our knowledge,nonvolatile,reconfigurable,and dynamic Janus metasurfaces by incorporating phase-change material Ge_(2)Se_(2)Te_(5)(GST)in the terahertz(THz)regime.First,we experimentally show the reversible switching characteristic of GST on large areas by applying a single nanosecond laser pulse,which exhibits excellent contrast of THz properties in both states.Then,we present a multiplex metasurface scheme.In each metasurface,three sets of structures are adopted,in which two sets integrate GST.The effective structures can be reversely modulated by the amorphization and crystallization of GST.As a proof of concept,the dynamic beam splitter,bifocal metalens,dual-mode focusing optical vortex generators,and switchable metalens/focusing optical vortex generators are designed,fabricated,and experimentally characterized,and can be switched reversibly and repeatedly with the help of optical and thermal stimuli.Our scheme will pave the way toward the development of multifunctional and compact THz devices and may find use for applications in THz imaging,sensing,and communications.
基金National Natural Science Foundation of China(62027821,11654002,11874250,12174234,62035015)National Key Research and Development Program of China(2020YFC2200402)+1 种基金Key Research and Development Program of Shanxi(201903D111001)Program for Sanjin Scholar of Shanxi Province。
文摘Quantum teleportation is a key primitive across a number of quantum information tasks and represents a fundamental ingredient for many quantum technologies. Channel capacity, other than the fidelity, becomes another focus of quantum communication. Here, we present a 5-channel multiplexing continuous-variable quantum teleportation protocol in the optical frequency comb system, exploiting five-order entangled sideband modes.Because of the resonant electro-optical modulation(EOM) that is specifically designed, the fidelities of five channels are greater than 0.78, which are superior to the no-cloning limit of 2∕3. This work provides a feasible scheme for implementing efficient quantum information processing.
基金supported by the National Natural Science Foundation of China for Distinguished Young Scholars (No. 51825403)the National Natural Science Foundation of China (No. 51904355)the National Key R&D Program of China (No. 2020YFC1909201)。
文摘Lead(Pb) coprecipitation with jarosite is common in natural and engineered environments,such as acid mine drainage(AMD) sites and hydrometallurgical industry. Despite the high relevance for environmental impact, few studies have examined the exact interaction of Pb with jarosite and the dissolution behavior of each phase. In the present work, we demonstrate that Pb mainly interacts with jarosite in four modes, namely incorporation, occlusion,physically mixing, and chemically mixing. For comparison, the four modes of Pb-bearing natrojarosite were synthesized and characterized separately. Batch dissolution experiments were undertaken on these synthetic Pb-bearing natrojarosites under pH_(2) to simulate the AMD environments. The introduction of Pb decreases the final Fe releasing efficiency of jarosite-type compounds from 18.18% to 3.45%-5.01%, showing a remarkable inhibition of their dissolution. For Pb releasing behavior, PbSO_(4) dissolves in preference to Pb-substituted natrojarosite, i.e.,(Na, Pb)-jarosite, which primarily results in the sharp increase of Pb releasing concentration(> 40 mg/L). PbSO_(4) occlusion by jarosite-type compounds can significantly reduce the release of Pb. The results of this study could provide useful information regarding Fe and Pb cycling in acidic natural and engineered environments.
基金National Key Research and Development Program of China(2017YFA0701004)National Natural Science Foundation of China(62075158,11974259,61735012,62025504,61875150,61935015)+1 种基金Tianjin Municipal Fund for Distinguished Young Scholars(18JCJQJC45600)Engineering and Physical Sciences Research Council(EP/P021859/1)。
文摘Metasurfaces consisting of artificial subwavelength structure arrays have shown unprecedented ability to manipulate the phase,amplitude,and polarization of light.Separate and complete control over different spin states,namely the orthogonal circular polarizations,has proven more challenging as compared to the control over orthogonal linear polarizations.Here,we present and experimentally demonstrate several spin-dependent wavefront control metasurfaces in the terahertz regime using all-silicon dielectric structures.Such spin-dependent allsilicon metasurfaces are easy to fabricate and have potential applications in spin-involved ultracompact and miniaturized terahertz optical systems as well as terahertz communication systems.
基金supported by the Natural Science Foundation of China (No. 51974379)the National Key R&D Program of China (No. 2017YFC0210401)+1 种基金the National Science Fund for Distinguished Young Scholars (No. 51825403)The Key Projects of Science and Technology of Hunan Province (No. 2017SK2420)。
文摘To meet the challenges posed by global arsenic water contamination, the Mg Al Mn-LDHs with extraordinary efficiency of arsenate removal was developed. In order to clarify the enhancement effect of the doped-Mn on the arsenate removal performance of the LDHs, the cluster models of the Mg Al Mn-LDHs and Mg Al-LDHs were established and calculated by using density functional theory(DFT). The results shown that the doped-Mn can significantly change the electronic structure of the LDHs and improve its chemical activity. Compared with the Mg Al-LDHs that without the doped-Mn, the HOMO-LUMO gap was smaller after doping. In addition, the-OH and Al on the laminates were also activated to improve the adsorption property of the LDHs. Besides, the doped-Mn existed as a novel active site. On the other hand, the Mg Al Mn-LDHs with the doped-Mn, the increased of the binding energy, as well as the decreased of the ion exchange energy of interlayer Cl^(-), making the ability to arsenate removal had been considerably elevated than the Mg Al-LDHs. Furthermore, there is an obvious coordination covalent bond between arsenate and the laminates of the Mg Al MnLDHs that with the doped-Mn.
