A field experiment was conducted to study the effects of Pb, Cd, Cu, Zn and As coexisting in red soilon growth of rice (Oryza sativa L.), mung bean (Vigna rabiata (Linn.) Wilczek), alfalfa (Medicago sativaL.), slash p...A field experiment was conducted to study the effects of Pb, Cd, Cu, Zn and As coexisting in red soilon growth of rice (Oryza sativa L.), mung bean (Vigna rabiata (Linn.) Wilczek), alfalfa (Medicago sativaL.), slash pine (Pinus elliottii Engelm.) and aspen (Populus L.). Results showed that rice, mung bean andalfalfa were significantly innuenced by combined pollution of the heavy metals. The contents of Pb, cd andAs in rice grains greatly exceeded the National Standards for Food Hygiene of China. Heavy metals at ahigh concentration seriously retarded growth of mung bean and alfalfa, but not so obviously with slash pineand aspen. The composite index is suggested for evaluating the relativity of combined pollution witll heavymetals in soil.展开更多
With the rapid advancement of 5G technology,the Internet of Things(IoT)has entered a new phase of appli-cations and is rapidly becoming a significant force in promoting economic development.Due to the vast amounts of ...With the rapid advancement of 5G technology,the Internet of Things(IoT)has entered a new phase of appli-cations and is rapidly becoming a significant force in promoting economic development.Due to the vast amounts of data created by numerous 5G IoT devices,the Ethereum platform has become a tool for the storage and sharing of IoT device data,thanks to its open and tamper-resistant characteristics.So,Ethereum account security is necessary for the Internet of Things to grow quickly and improve people's lives.By modeling Ethereum trans-action records as a transaction network,the account types are well identified by the Ethereum account classifi-cation system established based on Graph Neural Networks(GNNs).This work first investigates the Ethereum transaction network.Surprisingly,experimental metrics reveal that the Ethereum transaction network is neither optimal nor even satisfactory in terms of accurately representing transactions per account.This flaw may significantly impede the classification capability of GNNs,which is mostly governed by their attributes.This work proposes an Adaptive Multi-channel Bayesian Graph Attention Network(AMBGAT)for Ethereum account clas-sification to address this difficulty.AMBGAT uses attention to enhance node features,estimate graph topology that conforms to the ground truth,and efficiently extract node features pertinent to downstream tasks.An extensive experiment with actual Ethereum transaction data demonstrates that AMBGAT obtains competitive performance in the classification of Ethereum accounts while accurately estimating the graph topology.展开更多
Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials g...Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials grown by metal-organic chemical vapor deposition(MOCVD).High interface quality structures designed for light emission at 8.5μm are achieved by optimizing and precise controlling of growth conditions.A CW output power of 1.04 W at 288 K was obtained from a 4 mm-long and 10μm-wide coated laser.Corresponding maximum wall-plug efficiency and threshold current density were 7.1%and 1.18 kA/cm2,respectively.The device can operate in CW mode up to 408 K with an output power of 160 mW.展开更多
The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau＇s tectonic evolution. Here we present new findings on the deforma- tion ...The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau＇s tectonic evolution. Here we present new findings on the deforma- tion geometry and timing of the Wupoer thrust belt at the northeastem margin of Pamir. Field investigations and interpretations of seismic profiles indicate that the eastern portion of the Wupoer thrust belt is dominated by an underlying foreland basin and an overlying piggy-back basin. A regional unconformity occurs between the Pliocene （N2） and the underlying Miocene （NI） or Paleogene （Pg） strata associated with two other local unconformities between Lower Pleistocene （Q1） and N2 and between Middle Pleistocene （Q2-4） and Q1 strata. Results of structural restorations suggest that compres- sional deformation was initiated during the latest Miocene to earliest Pliocene, contributing a total shortening magnitude of 48.6 km with a total shortening rate of 48.12%, most of which occurred in the period from the latest Miocene to earliest Pliocene. These results, com- bined with previous studies on the Kongur and Tarshkor- gan extensional system, suggest an interesting picture of strong piedmont compressional thrusting activity concur- rent with interorogen extensional rifting. Combining these results with previously published work on the lithospheric architecture of the Pamir, we propose that gravitational collapse drove the formation of simultaneous extensional and compressional structures with a weak, ductile middle crustal layer acting as a decollement along which both the extensional and compressional faults merged.展开更多
Stoichiometry plays a crucial role in biogeochemical cycles and can modulate soil nutrient availability and functions. In agricultural ecosystems,phosphorus(P) fertilizers(organic or chemical) are often applied to ach...Stoichiometry plays a crucial role in biogeochemical cycles and can modulate soil nutrient availability and functions. In agricultural ecosystems,phosphorus(P) fertilizers(organic or chemical) are often applied to achieve high crop yields. However, P is readily fixed by soil particles, leading to low P use efficiency. Therefore, understanding the role of carbon:nitrogen:P stoichiometries of soil and microorganisms in soil P transformation is of great significance for P management in agriculture. This paper provides a comprehensive review of the recent research on stoichiometry effect on soil P transformation in agricultural ecosystems. Soil microorganisms play an important role in the transformation of soil non-labile inorganic P to microbial biomass P by regulating microbial biomass stoichiometry. They also mobilize soil unavailable organic P into available P by changing ecoenzyme stoichiometry. Organic materials, such as manure and straw, play an important role in promoting the transformation of insoluble P into available P as well. Additionally, periphytic biofilms can reduce P loss from rice field ecosystems. Agricultural stoichiometries are different from those of natural ecosystems and thereby should receive more attention due to the influences of anthropogenic factors. Therefore, it is necessary to conduct further stoichiometry research on the soil biochemical mechanisms underlying P transformation in agricultural ecosystems. In conclusion, understanding stoichiometry impact on soil P transformation is crucial for P management in agricultural ecosystems.展开更多
In this paper,a patch-antenna-array enhanced quantum cascade detector with freely switchable operating modes among mid-wave,long-wave,and dual-color was proposed and discussed.The dual-color absorption occurs in a sin...In this paper,a patch-antenna-array enhanced quantum cascade detector with freely switchable operating modes among mid-wave,long-wave,and dual-color was proposed and discussed.The dual-color absorption occurs in a single active region through an optimized coupled miniband diagonal-transition subbands arrangement,and a successful separation of the operation regimes was realized by two nested antenna arrays with different patch sizes up to room temperature.At 77 K,the 5.7-μm channel achieved a peak responsivity of 34.6 mA/W and exhibited a detectivity of 2.0×10^(10)Jones,while the 10.0-μm channel achieved a peak responsivity of 87.5 mA/W,giving a detectivity of 5.0×10^(10)Jones.Under a polarization modulation of the incident light,the minimum cross talk of the mid-wave and the long-wave operating modes was 1:22.5 and 1:7.6,respectively.This demonstration opens a new prospect for multicolor infrared imaging chip integration technology.展开更多
We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge l...We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode power.Due to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)cavities.The Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of ridges.We set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field distribution.This scheme provides a new approach for enhancing the single-mode power of THz QCLs.展开更多
To facilitate the development of on-chip integrated mid-infrared multi-channel gas sensing systems,we propose a high-power dual-mode(7.01 and 7.5μm)distributed feedback quantum cascade laser based on stacked 3D monol...To facilitate the development of on-chip integrated mid-infrared multi-channel gas sensing systems,we propose a high-power dual-mode(7.01 and 7.5μm)distributed feedback quantum cascade laser based on stacked 3D monolithic integration.Longitudinal mode control is achieved by preparing longitudinal nested bi-periodic compound one-dimensional Bragg gratings along the direction of the cavity length in the confinement layer.Additionally,transverse coherent coupling ridges perpendicular to the cavity length direction are fabricated in the upper waveguide layer to promote the fundamental transverse mode output when all ridges are in phase.Stable dual-wavelength simultaneous emission with a side-mode suppression ratio of more than 20 dB was achieved by holographic exposure and wet etching.The entire spectral tuning range covers nearly 100 nm through joint tuning of the injection current and heat-sink temperature.High peak power and beam quality are guaranteed by the parallel coherent integration of seven-element ridge arrays.The device operates in a fundamental supermode with a single-lobed far-field pattern,and its peak output power reaches 3.36 W in pulsed mode at 20℃.This dual-mode laser chip has the potential for in-situ on-chip simultaneous detection of CH4and C2H6gases in leak monitoring.展开更多
We report a high-power single-mode InP-based 2μm distributed feedback(DFB)laser with a second-order buried grating and corrugated sidewalls.A second-order semiconductor grating is used for in-plane feedback and verti...We report a high-power single-mode InP-based 2μm distributed feedback(DFB)laser with a second-order buried grating and corrugated sidewalls.A second-order semiconductor grating is used for in-plane feedback and vertical out-coupling.The corrugated sidewalls are used to eliminate higher-order transverse modes.For the DFB laser with a 2 mm long cavity and 15μm wide ridge,the maximum continuous-wave edge-emitting and surface-emitting single-mode powers at 300 K are up to 81 and 42 m W,respectively.A single-lobed far-field radiation pattern with a low divergence angle of approximately 8.6°is achieved by a device with a ridge width of 15μm.The single-longitudinal-mode emission wavelength of the fabricated laser can be adjusted from2003.8 nm at 288 K to 2006.9 nm at 313 K without any mode hopping.Robust single-mode emission with a side-mode suppression ratio of 30 dB is achieved under all injection currents and temperature conditions.展开更多
Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements,which is a very important an...Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements,which is a very important and popular research direction at present.As a IV-V two-dimensional material,silicon phosphide(SiP)has obvious in-plane anisotropy and exhibits excellent optical and electrical anisotropy properties.Herein,the optical anisotropy of SiP is studied by spectrometric ellipsometry measurements and polarization-resolved optical microscopy,and its electrical anisotropy is tested by SiP-based field-effect transistor.In addition,the normal and anisotropic photoelectric performance of SiP is shown by fabricating a photodetector and measuring it.In various measurements,SiP exhibits obvious anisotropy and good photoelectric performance.This work provides basic optical,electrical,and photoelectric performance information of SiP,and lays a foundation for further study of SiP and applications of SiP-based devices.展开更多
Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,...Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed.展开更多
InAs-based interband cascade lasers（ICLs） with InAs plasmon waveguides or InAs/AlSb superlattice（SL） waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the laser...InAs-based interband cascade lasers（ICLs） with InAs plasmon waveguides or InAs/AlSb superlattice（SL） waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the lasers with SL waveguides were 37 A/cm;at 77 K in continuous wave mode. The operation temperature of these lasers reached room temperature in pulsed mode. Compared with the thick InAs n++ plasmon cladding layer, the InAs/AlSb superlattice cladding layers have greater advantages for ICLs with wavelengths less than 4 μm even in InAs based ICLs because in the short-wavelength region they have a higher confinement factor than InAs plasmon waveguides.展开更多
<div style="text-align:justify;"> In this paper, we report a single-mode Fabry-Pérot long wave infrared quantum cascade lasers based on the double phonon resonance active region design. For room t...<div style="text-align:justify;"> In this paper, we report a single-mode Fabry-Pérot long wave infrared quantum cascade lasers based on the double phonon resonance active region design. For room temperature CW operation, the wafer with 35 stages was processed into buried heterostructure lasers. For a 4 mm long and 13 μm wide laser with high-reflectivity (HR) coating on the rear facet, continuous wave output power of 43 mW at 288 K and 5 mW at 303 K is obtained with threshold current densities of 2.17 and 2.7 kA/cm2. The lasing wavelength is around 10.5 μm. Single mode emission was observed for this particular device over the whole investigated current and temperature range. </div>展开更多
Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems.Ceramic aerogels promise high-temperature thermal insulation but lack...Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems.Ceramic aerogels promise high-temperature thermal insulation but lack mechanical robustness,while the fibrous materials with excellent mechanical elasticity display modest thermal insulation.Here we describe flexible hierarchical superhydrophobic ceramic insulation nanocomposites through the densified architectured hierarchical nanostructures,radiative insulation coating,and interfacial cross-linking among composites.The lightweight flexible ceramic nanocomposites exhibit a density of 0.13 g/cm^(3),high-temperature fire resistance with thermal conductivity of 0.024 W/(m·K),and super-hydrophobicity with the water contact angle of 152°.The mechanical robustness and high-temperature thermal insulation of ceramic nanocomposites,together with its soundproof performance,shed light on the low-cost flexible insulation materials manufacturing with scalability for high-temperature thermal insulation applications under high mechanical loading conditions.展开更多
Little attention has been paid to how long-term application of crop straw and its biochar affects soil phosphorus(P)transformation and carbon(C)fractions.We conducted a 7-year field experiment including control treatm...Little attention has been paid to how long-term application of crop straw and its biochar affects soil phosphorus(P)transformation and carbon(C)fractions.We conducted a 7-year field experiment including control treatment(chemical fertilizer only,CK),straw return(2.25 t ha^(−1)),and different amounts of biochar addition(11.25 t ha^(−1)(0.5%BC)and 22.5 t ha^(−1)(1.0%BC),to investigate influence of these amendments on soil C structure,P fractions,and their interaction with microorganisms.The 13C nuclear magnetic resonance and soil P sequence fractionation were applied to capture changes of soil C compositions and P pool.Compared to CK,straw and biochar amendments decreased alkyl C/O-alkyl C,which is conducive to increased soil organic C.The 0.5%BC and 1.0%BC treatments enhanced recalcitrant aromatic C by 69.0%and 131%,respectively.Compared to CK(101.2±33.32 mg kg^(−1)),the 0.5%BC and 1.0%BC treatments had a negligible effect on soil available P,while negative effects were observed in straw treatment(59.79±9.023 mg kg^(−1)).Straw and biochar amendments increased primary P and occluded P,whereas had negligible effect on organic P.Redundancy analysis and correlation analysis indi-cated that C compositions and P pool correlated to microbial community composition and enzyme activities,and aromatic C was the most related factor.Moreover,structural equation modeling indicated available P was most related to phosphatase activity and C composition.Our findings reveal the changes of soil P and C response under long-term crop straw and its biochar amendment,and can contribute toward improving understanding of the effect of biochar and straw return in future agriculture management.展开更多
We report on the terahertz(THz)quantum cascade lasers in continuous-wave(CW)operation with an emitting frequency above 5 THz.Excellent performance with a smaller leakage current and higher population inversion efficie...We report on the terahertz(THz)quantum cascade lasers in continuous-wave(CW)operation with an emitting frequency above 5 THz.Excellent performance with a smaller leakage current and higher population inversion efficiency is obtained by one-well bridged bound-to-continuum hybrid quantum design at 5 THz.By designing and fabricating a graded metallic sampled distributed feedback grating in the waveguide,the first single-mode THz quantum cascade laser at 5.13 THz in CW operation mode is achieved.The maximum single-mode optical power of~48 mW is achieved at 15 K with a side-mode suppression ratio above 24 dB.This will draw great interest in the spectroscopy applications above the 5 THz range for THz quantum cascade lasers.展开更多
Phosphorus(P)availability,diffusion,and resupply processes can be altered by biochar addition in flooded rice rhizosphere,which controls the risk of P release to the environment.However,there are few in-situ investiga...Phosphorus(P)availability,diffusion,and resupply processes can be altered by biochar addition in flooded rice rhizosphere,which controls the risk of P release to the environment.However,there are few in-situ investigations of these rhizospheric processes and effects.To explore the effects of biochar addition on soil P availability,high-resolution dialysis(HR-Peeper),diffusive gradients in thin films(DGT),and zymography techniques were used to provide direct evidence in the rice rhizosphere at the sub-millimeter scale.Long-term(9-years)field and greenhouse pot experiments demonstrated that biochar addition notably decreased the soluble/labile P and Fe concentrations in rice rhizosphere(vs.no biochar addition;CK)based on the results of Peeper,DGT,and two-dimensional imaging of labile P fluxes.DGT-induced fluxes in the soil/sediment(DIFS)model and sediment P release risk index(SPRRI)further indicated that biochar addition decreased the diffusion and resupply capacity of P from soil solid to the solution,thereby decreasing P release risk to the environment.These processes were dominated by Fe redox cycling and the hydrolysis of Al(hydro)oxides that greatly increased the unavailable P(Ca-P and residual-P).Additionally,greenhouse pot experiments(without additional biochar)showed that the previous long-term biochar addition significantly increased soil phosphatase activity,due to an adaptive-enhancing response to P decrease in the rhizosphere zone.The in-situ study on the biogeochemical reactions of P in the rice rhizosphere may provide a new and direct perspective to better evaluate the biochar addition and potential benefits to agricultural soils.展开更多
In rice-wheat rotation systems, changes in soil phosphorus(P) pools and microorganisms in rice-growing seasons have been studied;however, further investigations are required to test whether these indexes exhibit diffe...In rice-wheat rotation systems, changes in soil phosphorus(P) pools and microorganisms in rice-growing seasons have been studied;however, further investigations are required to test whether these indexes exhibit different responses in wheat-growing seasons. Additionally, such studies need to include potential variations in soil carbon(C) structure and microbial community composition. In this study, a long-term rice-wheat rotation P-input reduction experiment was conducted to observe the variations in soil P pools and C composition in the 7th wheat season and to investigate the responses of soil enzyme activity and microbial communities. Four P fertilization treatments were included in the experiment, i.e., P application for rice season only(PR), for wheat season only(PW), and for both rice and wheat seasons(PR+W) and no P application in either season(Pzero). Compared with PR+W treatment, Pzero treatment significantly decreased(P < 0.05) labile and stable P pools. Different P fertilization regimes altered soil microbial community composition and enzyme activity, whereas C composition did not vary. However, PW treatment resulted in relatively more O-alkyl-C than PR treatment and the highest number of microorganisms. Besides, the higher ratios of fungi/bacteria and Gram-positive bactetia/Gram-negative bactetia were related to labile C pools, particularly O-alkyl-C, as opposed to recalcitrant C. Our results clarified the status of soil P pools, C chemistry, and the response of microorganisms under dry-farming conditions in the P input-reduced rice-wheat rotation system.展开更多
Tree species and temperature change arising from seasonal variation or global warming are two important factors influencing N2O and NO emissions from forest soils. However, few studies have examined the effects of tem...Tree species and temperature change arising from seasonal variation or global warming are two important factors influencing N2O and NO emissions from forest soils. However, few studies have examined the effects of temperatures （5-35℃） on the emissions of forest soil N2O and NO in typical subtropical region. A short-term laboratory experiment was carried out to investigate the influence of temperature changes （5-35℃） on soil N2O and NO emissions under aerobic conditions in two contrasting （broad-leaved and coniferous） subtropical acidic forest types in China. The results showed that the temporal pattern of N2O and NO emissions between the three lower temperatures （5℃, 15℃, and 25℃） and 35℃ was significantly different for both broad-leaved and coniferous forest soils. The effects of temperature on soil N2O and NO emission rates varied between broad-leaved and coniferous forest soils. Both N2O and NO emissions increased exponentially with an increase in temperature in the broad-leaved forest soil. However, N2O and NO emissions in the coniferous forest soil were not sensitive to temperature change between 5℃ and 25℃. N2O and NO emission rates were significantly higher in the broad-leaved forest soil as compared with the coniferous forest soil at all incubation temperatures except 5℃. These results suggest that the broad-leaved forest could contribute more N2O and NO emissions than the coniferous forest for most of the year in the subtropical region of China.展开更多
文摘A field experiment was conducted to study the effects of Pb, Cd, Cu, Zn and As coexisting in red soilon growth of rice (Oryza sativa L.), mung bean (Vigna rabiata (Linn.) Wilczek), alfalfa (Medicago sativaL.), slash pine (Pinus elliottii Engelm.) and aspen (Populus L.). Results showed that rice, mung bean andalfalfa were significantly innuenced by combined pollution of the heavy metals. The contents of Pb, cd andAs in rice grains greatly exceeded the National Standards for Food Hygiene of China. Heavy metals at ahigh concentration seriously retarded growth of mung bean and alfalfa, but not so obviously with slash pineand aspen. The composite index is suggested for evaluating the relativity of combined pollution witll heavymetals in soil.
基金supported in part by the National Natural Science Foundation of China under Grant 62272405,School and Locality Integration Development Project of Yantai City(2022)the Youth Innovation Science and Technology Support Program of Shandong Provincial under Grant 2021KJ080+2 种基金the Natural Science Foundation of Shandong Province,Grant ZR2022MF238Yantai Science and Technology Innovation Development Plan Project under Grant 2021YT06000645the Open Foundation of State key Laboratory of Networking and Switching Technology(Beijing University of Posts and Telecommunications)under Grant SKLNST-2022-1-12.
文摘With the rapid advancement of 5G technology,the Internet of Things(IoT)has entered a new phase of appli-cations and is rapidly becoming a significant force in promoting economic development.Due to the vast amounts of data created by numerous 5G IoT devices,the Ethereum platform has become a tool for the storage and sharing of IoT device data,thanks to its open and tamper-resistant characteristics.So,Ethereum account security is necessary for the Internet of Things to grow quickly and improve people's lives.By modeling Ethereum trans-action records as a transaction network,the account types are well identified by the Ethereum account classifi-cation system established based on Graph Neural Networks(GNNs).This work first investigates the Ethereum transaction network.Surprisingly,experimental metrics reveal that the Ethereum transaction network is neither optimal nor even satisfactory in terms of accurately representing transactions per account.This flaw may significantly impede the classification capability of GNNs,which is mostly governed by their attributes.This work proposes an Adaptive Multi-channel Bayesian Graph Attention Network(AMBGAT)for Ethereum account clas-sification to address this difficulty.AMBGAT uses attention to enhance node features,estimate graph topology that conforms to the ground truth,and efficiently extract node features pertinent to downstream tasks.An extensive experiment with actual Ethereum transaction data demonstrates that AMBGAT obtains competitive performance in the classification of Ethereum accounts while accurately estimating the graph topology.
基金The authors would thank Ping Liang and Ying Hu for their help with device fabrication.This work was supported by the National Key Research and Development Program of China(Grant No.2020YFB0408401)in part by the National Natural Science Foundation of China(Grant Nos.61991430,61774146,61790583,61734006,61835011,61674144,61774150,61805168)+1 种基金in part by Beijing Municipal Science&Technology Commission(Grant No.Z201100004020006)in part by the Key Projects of the Chinese Academy of Sciences(Grant Nos.2018147,YJKYYQ20190002,QYZDJ-SSW-JSC027,XDB43000000,ZDKYYQ20200006).
文摘Robust quantum cascade laser(QCL)enduring high temperature continuous-wave(CW)operation is of critical importance for some applications.We report on the realization of lattice-matched InGaAs/InAlAs/InP QCL materials grown by metal-organic chemical vapor deposition(MOCVD).High interface quality structures designed for light emission at 8.5μm are achieved by optimizing and precise controlling of growth conditions.A CW output power of 1.04 W at 288 K was obtained from a 4 mm-long and 10μm-wide coated laser.Corresponding maximum wall-plug efficiency and threshold current density were 7.1%and 1.18 kA/cm2,respectively.The device can operate in CW mode up to 408 K with an output power of 160 mW.
文摘The Pamir region, located to the northwest of the Tibetan Plateau, provides important information that can aid the understanding of the plateau＇s tectonic evolution. Here we present new findings on the deforma- tion geometry and timing of the Wupoer thrust belt at the northeastem margin of Pamir. Field investigations and interpretations of seismic profiles indicate that the eastern portion of the Wupoer thrust belt is dominated by an underlying foreland basin and an overlying piggy-back basin. A regional unconformity occurs between the Pliocene （N2） and the underlying Miocene （NI） or Paleogene （Pg） strata associated with two other local unconformities between Lower Pleistocene （Q1） and N2 and between Middle Pleistocene （Q2-4） and Q1 strata. Results of structural restorations suggest that compres- sional deformation was initiated during the latest Miocene to earliest Pliocene, contributing a total shortening magnitude of 48.6 km with a total shortening rate of 48.12%, most of which occurred in the period from the latest Miocene to earliest Pliocene. These results, com- bined with previous studies on the Kongur and Tarshkor- gan extensional system, suggest an interesting picture of strong piedmont compressional thrusting activity concur- rent with interorogen extensional rifting. Combining these results with previously published work on the lithospheric architecture of the Pamir, we propose that gravitational collapse drove the formation of simultaneous extensional and compressional structures with a weak, ductile middle crustal layer acting as a decollement along which both the extensional and compressional faults merged.
基金financial support from the Natural Science Foundation of Jiangsu Province,China(No.BK20230049)the National Natural Science Foundation of China(No.42277026)+2 种基金the 14th Five-Year Plan Innovation Program of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSASIP2201)the Major Science and Technology of Inner Mongolia Autonomous Region,China(No.NMKJXM202009)the Program for Excellent Postdoctoral Talents of Jiangsu,China(No.2022ZB533)。
文摘Stoichiometry plays a crucial role in biogeochemical cycles and can modulate soil nutrient availability and functions. In agricultural ecosystems,phosphorus(P) fertilizers(organic or chemical) are often applied to achieve high crop yields. However, P is readily fixed by soil particles, leading to low P use efficiency. Therefore, understanding the role of carbon:nitrogen:P stoichiometries of soil and microorganisms in soil P transformation is of great significance for P management in agriculture. This paper provides a comprehensive review of the recent research on stoichiometry effect on soil P transformation in agricultural ecosystems. Soil microorganisms play an important role in the transformation of soil non-labile inorganic P to microbial biomass P by regulating microbial biomass stoichiometry. They also mobilize soil unavailable organic P into available P by changing ecoenzyme stoichiometry. Organic materials, such as manure and straw, play an important role in promoting the transformation of insoluble P into available P as well. Additionally, periphytic biofilms can reduce P loss from rice field ecosystems. Agricultural stoichiometries are different from those of natural ecosystems and thereby should receive more attention due to the influences of anthropogenic factors. Therefore, it is necessary to conduct further stoichiometry research on the soil biochemical mechanisms underlying P transformation in agricultural ecosystems. In conclusion, understanding stoichiometry impact on soil P transformation is crucial for P management in agricultural ecosystems.
基金National Natural Science Foundation of China(61835011,62335015,61991430,62174158,62222408,12274404)Chinese Academy of Sciences Key Project(XDB43000000,QYZDJ-SSW-JSC027)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021107,2022112)。
文摘In this paper,a patch-antenna-array enhanced quantum cascade detector with freely switchable operating modes among mid-wave,long-wave,and dual-color was proposed and discussed.The dual-color absorption occurs in a single active region through an optimized coupled miniband diagonal-transition subbands arrangement,and a successful separation of the operation regimes was realized by two nested antenna arrays with different patch sizes up to room temperature.At 77 K,the 5.7-μm channel achieved a peak responsivity of 34.6 mA/W and exhibited a detectivity of 2.0×10^(10)Jones,while the 10.0-μm channel achieved a peak responsivity of 87.5 mA/W,giving a detectivity of 5.0×10^(10)Jones.Under a polarization modulation of the incident light,the minimum cross talk of the mid-wave and the long-wave operating modes was 1:22.5 and 1:7.6,respectively.This demonstration opens a new prospect for multicolor infrared imaging chip integration technology.
基金funded by National Natural Science Foundation of China, grant numbers 62335006, 62274014, 62235016, 61734006, 61835011, 61991430funded by Key Program of the Chinese Academy of Sciences, grant numbers XDB43000000, QYZDJSSW-JSC027Beijing Municipal Science & Technology Commission, grant number Z221100002722018
文摘We demonstrated a scheme of phase-locked terahertz quantum cascade lasers(THz QCLs)array,with a single-mode pulse power of 108 mW at 13 K.The device utilizes a Talbot cavity to achieve phase locking among five ridge lasers with first-order buried distributed feedback(DFB)grating,resulting in nearly five times amplification of the single-mode power.Due to the optimum length of Talbot cavity depends on wavelength,the combination of Talbot cavity with the DFB grating leads to better power amplification than the combination with multimode Fabry-Perot(F-P)cavities.The Talbot cavity facet reflects light back to the ridge array direction and achieves self-imaging in the array,enabling phase-locked operation of ridges.We set the spacing between adjacent elements to be 220μm,much larger than the free-space wavelength,ensuring the operation of the fundamental supermode throughout the laser's dynamic range and obtaining a high-brightness far-field distribution.This scheme provides a new approach for enhancing the single-mode power of THz QCLs.
基金National Key Research and Development Program of China(2021YFB3201901)National Natural Science Foundation of China(61835011,61991430,62335015)Key Program of the Chinese Academy of Sciences(XDB43000000)。
文摘To facilitate the development of on-chip integrated mid-infrared multi-channel gas sensing systems,we propose a high-power dual-mode(7.01 and 7.5μm)distributed feedback quantum cascade laser based on stacked 3D monolithic integration.Longitudinal mode control is achieved by preparing longitudinal nested bi-periodic compound one-dimensional Bragg gratings along the direction of the cavity length in the confinement layer.Additionally,transverse coherent coupling ridges perpendicular to the cavity length direction are fabricated in the upper waveguide layer to promote the fundamental transverse mode output when all ridges are in phase.Stable dual-wavelength simultaneous emission with a side-mode suppression ratio of more than 20 dB was achieved by holographic exposure and wet etching.The entire spectral tuning range covers nearly 100 nm through joint tuning of the injection current and heat-sink temperature.High peak power and beam quality are guaranteed by the parallel coherent integration of seven-element ridge arrays.The device operates in a fundamental supermode with a single-lobed far-field pattern,and its peak output power reaches 3.36 W in pulsed mode at 20℃.This dual-mode laser chip has the potential for in-situ on-chip simultaneous detection of CH4and C2H6gases in leak monitoring.
基金National Key Research and Development Program of China(2021YFB3201900)National Natural Science Foundation of China(61991430,62235016)+1 种基金Youth Innovation Promotion Association of CAS(2022112,Y2022046)Key Projects of the Chinese Academy of Sciences(XDB43000000)。
文摘We report a high-power single-mode InP-based 2μm distributed feedback(DFB)laser with a second-order buried grating and corrugated sidewalls.A second-order semiconductor grating is used for in-plane feedback and vertical out-coupling.The corrugated sidewalls are used to eliminate higher-order transverse modes.For the DFB laser with a 2 mm long cavity and 15μm wide ridge,the maximum continuous-wave edge-emitting and surface-emitting single-mode powers at 300 K are up to 81 and 42 m W,respectively.A single-lobed far-field radiation pattern with a low divergence angle of approximately 8.6°is achieved by a device with a ridge width of 15μm.The single-longitudinal-mode emission wavelength of the fabricated laser can be adjusted from2003.8 nm at 288 K to 2006.9 nm at 313 K without any mode hopping.Robust single-mode emission with a side-mode suppression ratio of 30 dB is achieved under all injection currents and temperature conditions.
基金the National Natural Science Foundation of China(Nos.62125404,62174155,62004193,12004375,and 51727809)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB43000000)the CAS-JSPS Cooperative Research Project(No.GJHZ2021131)the Youth Innovation Promotion Association of CAS(No.2022112).
文摘Two-dimensional anisotropic materials have been widely concerned by researchers because of their great application potential in the field of polarized detector devices and optical elements,which is a very important and popular research direction at present.As a IV-V two-dimensional material,silicon phosphide(SiP)has obvious in-plane anisotropy and exhibits excellent optical and electrical anisotropy properties.Herein,the optical anisotropy of SiP is studied by spectrometric ellipsometry measurements and polarization-resolved optical microscopy,and its electrical anisotropy is tested by SiP-based field-effect transistor.In addition,the normal and anisotropic photoelectric performance of SiP is shown by fabricating a photodetector and measuring it.In various measurements,SiP exhibits obvious anisotropy and good photoelectric performance.This work provides basic optical,electrical,and photoelectric performance information of SiP,and lays a foundation for further study of SiP and applications of SiP-based devices.
基金supported by National Key Research and Development Program of China (Grant No.2021YFB3201900)National Natural Science Foundation of China (Grant Nos.61991430,62235016)+1 种基金Youth Innovation Promotion Association of CAS (Grant Nos.2022112,Y2022046)Key projects of the Chinese Academy of Sciences (Grant No.XDB43000000)。
文摘Sharing the advantages of high optical power,high efficiency and design flexibility in a compact size,quantum cascade lasers(QCLs)are excellent mid-to-far infrared laser sources for gas sensing,infrared spectroscopic,medical diagnosis,and defense applications.Metalorganic chemical vapor deposition(MOCVD)is an important technology for growing high quality semiconductor materials,and has achieved great success in the semiconductor industry due to its advantages of high efficiency,short maintenance cycles,and high stability and repeatability.The utilization of MOCVD for the growth of QCL materials holds a significant meaning for promoting the large batch production and industrial application of QCL devices.This review summarizes the recent progress of QCLs grown by MOCVD.Material quality and the structure design together determine the device performance.Research progress on the performance improvement of MOCVD-grown QCLs based on the optimization of material quality and active region structure are mainly reviewed.
基金Project supported by the National Natural Science Foundation of China(Nos.61790583,61774150,61774151)the National Basic Research Program of China(No.2014CB643903)
文摘InAs-based interband cascade lasers（ICLs） with InAs plasmon waveguides or InAs/AlSb superlattice（SL） waveguides were demonstrated at emission wavelengths below 4.1 μm. The threshold current densities of the lasers with SL waveguides were 37 A/cm;at 77 K in continuous wave mode. The operation temperature of these lasers reached room temperature in pulsed mode. Compared with the thick InAs n++ plasmon cladding layer, the InAs/AlSb superlattice cladding layers have greater advantages for ICLs with wavelengths less than 4 μm even in InAs based ICLs because in the short-wavelength region they have a higher confinement factor than InAs plasmon waveguides.
文摘<div style="text-align:justify;"> In this paper, we report a single-mode Fabry-Pérot long wave infrared quantum cascade lasers based on the double phonon resonance active region design. For room temperature CW operation, the wafer with 35 stages was processed into buried heterostructure lasers. For a 4 mm long and 13 μm wide laser with high-reflectivity (HR) coating on the rear facet, continuous wave output power of 43 mW at 288 K and 5 mW at 303 K is obtained with threshold current densities of 2.17 and 2.7 kA/cm2. The lasing wavelength is around 10.5 μm. Single mode emission was observed for this particular device over the whole investigated current and temperature range. </div>
基金We gratefully acknowledge support from the U.S.Department of Energy(DOE),Office of Energy Efficiency and Renewable Energy(EERE)under the Building Technology Office(BTO)Award(No.DE-EE0008675).
文摘Flexible and lightweight thermal insulation materials with hierarchical microstructures are ubiquitous in thermal management and protection systems.Ceramic aerogels promise high-temperature thermal insulation but lack mechanical robustness,while the fibrous materials with excellent mechanical elasticity display modest thermal insulation.Here we describe flexible hierarchical superhydrophobic ceramic insulation nanocomposites through the densified architectured hierarchical nanostructures,radiative insulation coating,and interfacial cross-linking among composites.The lightweight flexible ceramic nanocomposites exhibit a density of 0.13 g/cm^(3),high-temperature fire resistance with thermal conductivity of 0.024 W/(m·K),and super-hydrophobicity with the water contact angle of 152°.The mechanical robustness and high-temperature thermal insulation of ceramic nanocomposites,together with its soundproof performance,shed light on the low-cost flexible insulation materials manufacturing with scalability for high-temperature thermal insulation applications under high mechanical loading conditions.
基金Jiangsu Agriculture Science and Technology Innovation Fund(CX(19)1007)the National Natural Science Foundation of China(No.41671304).
文摘Little attention has been paid to how long-term application of crop straw and its biochar affects soil phosphorus(P)transformation and carbon(C)fractions.We conducted a 7-year field experiment including control treatment(chemical fertilizer only,CK),straw return(2.25 t ha^(−1)),and different amounts of biochar addition(11.25 t ha^(−1)(0.5%BC)and 22.5 t ha^(−1)(1.0%BC),to investigate influence of these amendments on soil C structure,P fractions,and their interaction with microorganisms.The 13C nuclear magnetic resonance and soil P sequence fractionation were applied to capture changes of soil C compositions and P pool.Compared to CK,straw and biochar amendments decreased alkyl C/O-alkyl C,which is conducive to increased soil organic C.The 0.5%BC and 1.0%BC treatments enhanced recalcitrant aromatic C by 69.0%and 131%,respectively.Compared to CK(101.2±33.32 mg kg^(−1)),the 0.5%BC and 1.0%BC treatments had a negligible effect on soil available P,while negative effects were observed in straw treatment(59.79±9.023 mg kg^(−1)).Straw and biochar amendments increased primary P and occluded P,whereas had negligible effect on organic P.Redundancy analysis and correlation analysis indi-cated that C compositions and P pool correlated to microbial community composition and enzyme activities,and aromatic C was the most related factor.Moreover,structural equation modeling indicated available P was most related to phosphatase activity and C composition.Our findings reveal the changes of soil P and C response under long-term crop straw and its biochar amendment,and can contribute toward improving understanding of the effect of biochar and straw return in future agriculture management.
基金National Natural Science Foundation of China(61734006,61835011,61991403)Key Program of the Chinese Academy of Sciences(XDB43000000,QYZDJSSW-JSC027)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021107)。
文摘We report on the terahertz(THz)quantum cascade lasers in continuous-wave(CW)operation with an emitting frequency above 5 THz.Excellent performance with a smaller leakage current and higher population inversion efficiency is obtained by one-well bridged bound-to-continuum hybrid quantum design at 5 THz.By designing and fabricating a graded metallic sampled distributed feedback grating in the waveguide,the first single-mode THz quantum cascade laser at 5.13 THz in CW operation mode is achieved.The maximum single-mode optical power of~48 mW is achieved at 15 K with a side-mode suppression ratio above 24 dB.This will draw great interest in the spectroscopy applications above the 5 THz range for THz quantum cascade lasers.
基金the National Natural Science Foundation of China(No.42277026)the National Key Research and Development Program of China(2021YFD1700802)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA28090300).
文摘Phosphorus(P)availability,diffusion,and resupply processes can be altered by biochar addition in flooded rice rhizosphere,which controls the risk of P release to the environment.However,there are few in-situ investigations of these rhizospheric processes and effects.To explore the effects of biochar addition on soil P availability,high-resolution dialysis(HR-Peeper),diffusive gradients in thin films(DGT),and zymography techniques were used to provide direct evidence in the rice rhizosphere at the sub-millimeter scale.Long-term(9-years)field and greenhouse pot experiments demonstrated that biochar addition notably decreased the soluble/labile P and Fe concentrations in rice rhizosphere(vs.no biochar addition;CK)based on the results of Peeper,DGT,and two-dimensional imaging of labile P fluxes.DGT-induced fluxes in the soil/sediment(DIFS)model and sediment P release risk index(SPRRI)further indicated that biochar addition decreased the diffusion and resupply capacity of P from soil solid to the solution,thereby decreasing P release risk to the environment.These processes were dominated by Fe redox cycling and the hydrolysis of Al(hydro)oxides that greatly increased the unavailable P(Ca-P and residual-P).Additionally,greenhouse pot experiments(without additional biochar)showed that the previous long-term biochar addition significantly increased soil phosphatase activity,due to an adaptive-enhancing response to P decrease in the rhizosphere zone.The in-situ study on the biogeochemical reactions of P in the rice rhizosphere may provide a new and direct perspective to better evaluate the biochar addition and potential benefits to agricultural soils.
基金funded by the National Natural Science Foundation of China (No. 41671304)the National Key Research and Development Program of China (No. 2017YFD0200206)。
文摘In rice-wheat rotation systems, changes in soil phosphorus(P) pools and microorganisms in rice-growing seasons have been studied;however, further investigations are required to test whether these indexes exhibit different responses in wheat-growing seasons. Additionally, such studies need to include potential variations in soil carbon(C) structure and microbial community composition. In this study, a long-term rice-wheat rotation P-input reduction experiment was conducted to observe the variations in soil P pools and C composition in the 7th wheat season and to investigate the responses of soil enzyme activity and microbial communities. Four P fertilization treatments were included in the experiment, i.e., P application for rice season only(PR), for wheat season only(PW), and for both rice and wheat seasons(PR+W) and no P application in either season(Pzero). Compared with PR+W treatment, Pzero treatment significantly decreased(P < 0.05) labile and stable P pools. Different P fertilization regimes altered soil microbial community composition and enzyme activity, whereas C composition did not vary. However, PW treatment resulted in relatively more O-alkyl-C than PR treatment and the highest number of microorganisms. Besides, the higher ratios of fungi/bacteria and Gram-positive bactetia/Gram-negative bactetia were related to labile C pools, particularly O-alkyl-C, as opposed to recalcitrant C. Our results clarified the status of soil P pools, C chemistry, and the response of microorganisms under dry-farming conditions in the P input-reduced rice-wheat rotation system.
基金This work was supported by the National Natural Science Foundation of China （No. 41301238, 41222005）, and the National Water Pollution Control and Management Technology Major Projects of China （No. 2011ZX07101004）.
文摘Tree species and temperature change arising from seasonal variation or global warming are two important factors influencing N2O and NO emissions from forest soils. However, few studies have examined the effects of temperatures （5-35℃） on the emissions of forest soil N2O and NO in typical subtropical region. A short-term laboratory experiment was carried out to investigate the influence of temperature changes （5-35℃） on soil N2O and NO emissions under aerobic conditions in two contrasting （broad-leaved and coniferous） subtropical acidic forest types in China. The results showed that the temporal pattern of N2O and NO emissions between the three lower temperatures （5℃, 15℃, and 25℃） and 35℃ was significantly different for both broad-leaved and coniferous forest soils. The effects of temperature on soil N2O and NO emission rates varied between broad-leaved and coniferous forest soils. Both N2O and NO emissions increased exponentially with an increase in temperature in the broad-leaved forest soil. However, N2O and NO emissions in the coniferous forest soil were not sensitive to temperature change between 5℃ and 25℃. N2O and NO emission rates were significantly higher in the broad-leaved forest soil as compared with the coniferous forest soil at all incubation temperatures except 5℃. These results suggest that the broad-leaved forest could contribute more N2O and NO emissions than the coniferous forest for most of the year in the subtropical region of China.
