东北黑土区水土资源配置及其空间格局优化

在水资源刚性约束条件下,如何综合考虑多个目标实现东北黑土区水土资源优化配置仍是有待解决的国际前沿问题.因此,本研究首先分析了该地区水土资源演变规律,然后研发了基于水-碳-经济-生态耦合的水土资源优化配置模型,通过NSGAⅢ智能算法对模型进行求解,最终在4种情景下对黑土区40个城市水土资源进行优化配置和生态安全保障分析.结果表明:(1)在气候变化和人类活动的影响下,1980年之后水田和旱田面积分别增加了91%和14%,林地、草地和湿地分别减少了2%、27%和10%.(2)2001~2020年东北黑土区平均水资源总量为1972亿m^(3),大部分城市的地表水资源量、地下水资源量以及水资源总量呈现增加趋势.(3)4种情景下,东北黑土区主要粮食作物的毛灌溉需水量在491~722亿m^(3)之间.通过优化配置后,在平水年通过增强节水,水稻种植面积仍可增加13.7%;其余水平年通过调整种植结构和增强节水也可大幅度提高粮食产量、农民收入、固碳量和生态效益,减少水资源开发利用,保障东北黑土区粮食安全和生态安全.针对目前水土资源存在的问题,提出了相关对策建议,为东北黑土区粮食增产工程和生态安全提供策略支撑.

Risk assessment of agricultural green water security in Northeast China under climate change

Northeast China is an important base for grain production,dominated by rain-fed agriculture that relies on green water.However,in the context of global climate change,rising regional temperatures,changing precipitation patterns,and increasing drought frequency pose threats and challenges to agricultural green water security.This study provides a detailed assessment of the spatiotemporal characteristics and development trends of green water security risks in the Northeast region under the base period(2001-2020)and the future(2031-2090)climate change scenarios(SSP245 and SSP585)using the green water scarcity(GWS)index based on raster-scale crop spatial distribution data,Delta downscaling bias-corrected ERA5 data,and CMIP6 multimodal data.During the base period,the green water risk-free zone for dry crops is mainly distributed in the center and east of the Northeast region(72.4% of the total area),the low-risk zone is primarily located in the center(14.0%),and the medium-risk(8.3%)and high-risk(5.3%)zones are mostly in the west.Under SSP245 and SSP585 future climate change scenarios,the green water security risk shows an overall expansion from the west to the center and east,with the low-risk zone increasing to 21.6% and 23.8%,the medium-risk zone increasing to 16.0% and 17.9%,and the high-risk zone increasing to 6.9% and 6.8%,respectively.Considering dry crops with GWS greater than 0.1 as in need of irrigation,the irrigated area increases from 27.6%(base period)to 44.5%(SSP245)and 48.6%(SSP585),with corresponding increases in irrigation water requirement(IWR)of 4.64 and 5.92 billion m~3,respectively,which further exacerbates conflicts between supply and demand of agricultural water resources.In response to agricultural green water security risks,coping strategies such as evapotranspiration(ET)-based water resource management for dry crops and deficit irrigation are proposed.The results of this study can provide scientific basis and decision support for the development of Northeast irrigated agriculture and the construction planning of the national water network.

Asymmetric electric field distribution enhanced hierarchical metamaterials for radar-infrared compatible camouflage

Metamaterials are widely used in electromagnetic radiation and camouflage for their flexible wavefront manipulation and polarization over a broad spectrum ranging from microwaves to optics.However,multispectral compatible camouflage faces significant challenges due to tremendous scale differences of unit cells and desired radiative properties in various spectral regimes.This study assembles a micron-scale infrared emitter,a millimeter-scale microwave absorber,and a metal reflector to propose a hierarchical metamaterial that reduces microwave scattering and reflects low-infrared waves.As a proof of concept,laser etching micro-manufactures an upper infrared shielding layer with a periodic metal pattern.At the same time,bottom square frustum metastructure composites are fabricated and optimized based on genetic algorithms.Under the normal incidence transverse electromagnetic wave with a 90°azimuth angle,the hierarchical strategy and infrared unit create an asymmetric electric field distribution of local near-field coupling,which is conducive to generating additional resonance for broadening the absorption bandwidth.Experiments verify the multispectral camouflage,which shows a high absorption efficiency of more than 90%,ranging from 3.6 to 6.2 and from 8.4 to 18 GHz with a total thickness of 4.05 mm(0.049λmax).Due to the non-reflection of surrounding thermal signals in the infrared 2-22μm region,low-infrared emissivity(0.29)metamaterials can adapt to various thermal backgrounds.This methodology can provide a novel route for fabricating multispectral camouflage devices.

An inactivated recombinant rabies virus chimerically expressed RBD induces humoral and cellular immunity against SARS-CoV-2 and RABV

Many studies suggest that severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)can infect various animals and transmit among animals,and even to humans,posing a threat to humans and animals.There is an urgent need to develop inexpensive and efficient animal vaccines to prevent and control coronavirus disease 2019(COVID-19)in animals.Rabies virus(RABV)is another important zoonotic pathogen that infects almost all warmblooded animals and poses a great public health threat.The present study constructed two recombinant chimeric viruses expressing the S1 and RBD proteins of the SARS-CoV-2 Wuhan01 strain based on a reverse genetic system of the RABV SRV9 strain and evaluated their immunogenicity in mice,cats and dogs.The results showed that both inactivated recombinant viruses induced durable neutralizing antibodies against SARS-CoV-2 and RABV and a strong cellular immune response in mice.Notably,inactivated SRV-nCoV-RBD induced earlier antibody production than SRV-nCoV-S1,which was maintained at high levels for longer periods.Inactivated SRV-nCoV-RBD induced neutralizing antibodies against both SARS-CoV-2 and RABV in cats and dogs,with a relatively broadspectrum cross-neutralization capability against the SARS-CoV-2 pseudoviruses including Alpha,Beta,Gamma,Delta,and Omicron,showing potential to be used as a safe bivalent vaccine candidate against COVID-19 and rabies in animals.

Incorporation of Escherichia coli heat-labile enterotoxin B subunit into rabies virus particles enhances its immunogenicity in mice and dogs

Although inactivated vaccines against rabies have the advantage of high safety,effective protection against rabies virus(RABV)infection often requires multiple,high-dose immunization.Incorporating a molecular adjuvant into the viral particles has been found to be a useful strategy to promote the immune effectiveness of inactivated vaccines.In this study,we constructed a recombinant virus,rCVS11-LTB,which chimerically expresses a molecular adjuvant heat-labile enterotoxin B subunit(LTB)protein on the surface of the RABV particles.Immunogenicity in vivo was found to be promoted by rCVS11-LTB through the activation of dendritic cells(DCs).Our results demonstrated that inactivated rCVS11-LTB was able to induce higher levels of virusneutralizing antibodies(VNAs)in both mice and dogs than the parent virus rCVS11,to enhance the cellular immune response and T cell immune memory in mice,and was also able to provide 100%protection in mice from lethal doses of rabies virus,indicating its potential as a safe and effective inactivated rabies vaccine candidate.

Spatiotemporal nonlinear dynamics in multimode fiber laser based on carbon nanotubes

We investigated 1-μm multimode fiber laser based on carbon nanotubes,where multiple typical pulse states were observed,including Q-switched,Q-switched mode-locked,and spatiotemporal mode-locked pulses.Particularly,stable spatiotemporal mode-locking was realized with a low threshold,where the pulse duration was 37 ps and the wavelength was centred at 1060.5 nm.Moreover,both the high signal to noise and long-term operation stability proved the reliability of the mode-locked laser.Furthermore,the evolution of the spatiotemporal mode-locked pulses in the cavity was also simulated and discussed.This work exhibits the flexible outputs of spatiotemporal phenomena in multimode lasers based on nanomaterials,providing more possibilities for the development of high-dimensional nonlinear dynamics.