长江口滨海湿地有机碳循环过程及影响因素研究进展

滨海湿地是“蓝碳生态系统”的重要组成部分。综述了长江口滨海湿地土壤有机碳时空分布及含量、碳汇速率、有机碳横向输入输出通量及量化方法、有机碳循环定量分析模型以及有机碳储量和组分对不同影响因素所做出的动态响应规律,发现在土壤有机碳水平空间分布上,崇西湿地>崇明东滩>九段沙>南汇潮滩;有机碳通量和浓度变化主要受到植物生物量和结构、水和土壤的理化性质、陆源输入和潮汐动力、间隙水交换以及人类活动和全球气候变化的影响。未来应加强长江口湿地土壤碳库和有机碳输运通量统一观测,准确量化各主要因素对有机碳的贡献,这对研究盐沼湿地的碳循环机理和碳汇评估具有重要意义。

高温后再生保温混凝土损伤劣化数值分析

【目的】内部多孔且高温稳定的玻化微珠(glazed hollow beads,GHB)可在一定程度上减缓混凝土的高温损伤劣化,提升混凝土的抗火性能。为了进一步明确GHB改善混凝土抗火性能的机理,从细观尺度出发,提出一种可考虑初始缺陷和再生骨料(recycled coarse aggregate,RCA)取代率的再生保温混凝土(recycled aggregate concrete mixed with glazed hollow beads,RATIC)细观模型的建模方法。【方法】利用现阶段比较常用的塑性损伤模型,探究了RCA取代率(0,50%,100%)、GHB含量(0,70%,100%)和孔隙率(0,2%,4%)对于高温后RATIC力学性能的影响。【结果】结果表明:随着受火温度的提高,荷载作用下RATIC试件的损伤分布均呈现出逐渐加剧的趋势,且500℃后,试件的损伤分布较400℃之前严重。GHB的加入可在一定程度上缓减混凝土内部的损伤劣化,而RCA的加入会加剧此现象。此外,随着孔隙率增大,RATIC试件的强度逐渐变低。

High-speed performance self-powered short wave ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)

High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.

Predicting impact strength of perforated targets using artificial neural networks trained on FEM-generated datasets

The paper considers application of artificial neural networks(ANNs)for fast numerical evaluation of a residual impactor velocity for a family of perforated PMMA(Polymethylmethacrylate)targets.The ANN models were trained using sets of numerical results on impact of PMMA plates obtained via dynamic FEM coupled with incubation time fracture criterion.The developed approach makes it possible to evaluate the impact strength of a particular target configuration without complicated FEM calculations which require considerable computational resources.Moreover,it is shown that the ANN models are able to predict results for the configurations which cannot be processed using the developed FEM routine due to numerical instabilities and errors:the trained neural network uses information from successful computations to obtain results for the problematic cases.A simple static problem of a perforated plate deformation is discussed prior to the impact problem and preferable ANN architectures are presented for both problems.Some insight into the perforation pattern optimization using a genetic algorithm coupled with the ANN is also made and optimized perforation patterns which theoretically enhance the target impact strength are constructed.

Cross-method Analysis of Corotation Radii Data Set for Spiral Galaxies

A corotation radius is a key characteristic of disk galaxies that is essential to determine the angular speed of the spiral structureΩ_p,and therefore understand its nature.In the literature,there are plenty of methods to estimate this value,but do these measurements have any consistency?In this work,we collected a data set of corotation radius measurements for 547 galaxies,300 of which had at least two values.An initial analysis reveals that most objects have rather inconsistent corotation radius positions.Moreover,a significant fraction of galactic disks is distinguished by a large error coverage and almost uniform distribution of measurements.These findings do not have any relation to spiral type,Hubble classification,or presence of a bar.Among other reasons,obtained results could be explained by the transient nature of spirals in a considerable part of galaxies.We have made our collected data sample publicly available,and have demonstrated on one example how it could be useful for future research by investigating a winding time value for a sample of galaxies with possible multiple spiral arm patterns.

Feasibility of compacted attapulgite/diatomite amended clayey soils as gas barrier materials

Compacted clay liners are extensively used as barriers to control the upward diffusion of vapors of volatile or semi-volatile organic contaminants released from unsaturated contaminated soils at industrycontaminated sites.This study aimed to investigate the gas diffusion barrier performance of compacted clayey soils amended with three agents including attapulgite and diatomite individually,and attapulgite/diatomite mixture.The properties including water retention,volumetric shrinkage,gas diffusion,and unconfined compressive strength were evaluated through a series of laboratory tests of amended compacted clayey soils.The results demonstrate that the decrease in volume proportions of interaggregate pores leads to an increase in unconfined compressive strength(qu).Both hydrophilic groups and microstructures of attapulgite and diatomite result in an increase in water retention percent(Wt)of compacted clayey soil specimens after amendment regardless of the type of agent or initial water content(w0).Furthermore,the ratio of the gas diffusion coefficient(De)to the gas diffusion coefficient in the air(Da)was significantly reduced owing to a decrease in volume proportions of inter-aggregate pores,hydrophilic group,and microstructures of attapulgite and diatomite.Scanning electron microscope analyses revealed that rod-shaped attapulgite filled the inter-aggregate pores formed by clay particles,whereas the disc-shaped diatomite particles,characterized by micropores,failed to obstruct the interaggregate pores due to their larger particle size.Mercury intrusion porosimetry(MIP)analyses showed a reduction in pore volume in the inter-aggregate pores,leading to a reduction in the total pore volume for both the attapulgite and attapulgite/diatomite mixture amended clays,which is in accordance with the scanning electron microscope(SEM)results.The findings are pertinent to the practical application of compacted clay liners as gas barriers against the upward migration of volatile or semi-volatile organic contaminants at contaminated sites.

Isochrone Fitting of Galactic Globular Clusters—Ⅵ.High-latitude Clusters NGC 5024 (M53),NGC 5053,NGC 5272 (M3),NGC 5466,and NGC7099 (M30)

We fit various color–magnitude diagrams(CMDs) of the high-latitude Galactic globular clusters NGC 5024(M53),NGC 5053,NGC 5272(M3),NGC 5466,and NGC 7099(M30) by isochrones from the Dartmouth Stellar Evolution Database and Bag of Stellar Tracks and Isochrones for α–enrichment [α/Fe] = +0.4.For the CMDs,we use data sets from Hubble Space Telescope,Gaia,and other sources utilizing,at least,25 photometric filters for each cluster.We obtain the following characteristics with their statistical uncertainties for NGC 5024,NGC 5053,NGC 5272,NGC 5466,and NGC 7099,respectively:metallicities [Fe/H] =-1.93 ± 0.02,-2.08 ± 0.03,-1.60 ± 0.02,-1.95 ± 0.02,and-2.07 ± 0.04 dex with their systematic uncertainty 0.1 dex;ages 13.00 ± 0.11,12.70 ± 0.11,11.63 ± 0.07,12.15 ± 0.11,and 12.80 ± 0.17 Gyr with their systematic uncertainty 0.8 Gyr;distances(systematic uncertainty added) 18.22 ± 0.06 ± 0.60,16.99 ± 0.06 ± 0.56,10.08 ± 0.04 ± 0.33,15.59 ±0.03 ± 0.51,and 8.29 ± 0.03 ± 0.27 kpc;reddenings E(B-V) = 0.023 ± 0.004,0.017 ± 0.004,0.023 ± 0.004,0.023 ± 0.003,and 0.045 ± 0.002 mag with their systematic uncertainty 0.01 mag;extinctions AV= 0.08 ± 0.01,0.06 ± 0.01,0.08 ± 0.01,0.08 ± 0.01,and 0.16 ± 0.01 mag with their systematic uncertainty 0.03 mag,which suggest the total Galactic extinction AV= 0.08 across the whole Galactic dust to extragalactic objects at the North Galactic Pole.The horizontal branch morphology difference of these clusters is explained by their different metallicity,age,mass-loss efficiency,and loss of low-mass members in the evolution of the core-collapse cluster NGC 7099 and loose clusters NGC 5053 and NGC 5466.

The sudden ocean warming and its potential influences on earlyfrozen landfast ice in the Prydz Bay, East Antarctica

The ocean conditions beneath the ice cover play a key role in understanding the sea ice mass balance in the polar regions.An integrated high-frequency ice-ocean observation system,including Acoustic Doppler Velocimeter,Conductivity-Temperature-Depth Sensor,and Sea Ice Mass Balance Array(SIMBA),was deployed in the landfast ice region close to the Chinese Zhongshan Station in Antarctica.A sudden ocean warming of 0.14℃(p<0.01)was observed beneath early-frozen landfast ice,from(−1.60±0.03)℃during April 16-19 to(−1.46±0.07)℃during April 20-23,2021,which is the only significant warming event in the nearly 8-month records.The sudden ocean warming brought a double rise in oceanic heat flux,from(21.7±11.1)W/m^(2) during April 16-19 to(44.8±21.3)W/m^(2) during April 20-23,2021,which shifted the original growth phase at the ice bottom,leading to a 2 cm melting,as shown from SIMBA and borehole observations.Simultaneously,the slowdown of ice bottom freezing decreased salt rejection,and the daily trend of observed ocean salinity changed from+0.02 d^(-1) during April 16-19,2021 to+0.003 d^(-1) during April 20-23,2021.The potential reasons are increased air temperature due to the transit cyclones and the weakened vertical ocean mixing due to the tide phase transformation from semi-diurnal to diurnal.The high-frequency observations within the ice-ocean boundary layer enhance the comprehensive investigation of the ocean’s influence on ice evolution at a daily scale.

基于热裂纹演化的玻化微珠保温混凝土渗透性能分析

为了改善火灾后混凝土结构耐久性退化问题,利用玻化微珠(GHB)的高热稳定性对混凝土耐高温性能进行提升,通过电通量法对高温后玻化微珠保温混凝土(GIC)的抗氯离子侵蚀性能进行测试,并结合混凝土试件热裂纹演化特征对其抗氯离子侵蚀性能劣化规律进行分析.结果表明:GHB的掺加显著改善了高温后混凝土抗氯离子渗透能力退化问题,与同强度等级的普通混凝土(NC)和硅灰混凝土(SFC)相比,掺加GHB后混凝土的电通量分别降低了约54.15%、32.69%.结合各试件热裂纹演化规律,认为这归因于GHB和硅灰对混凝土密实性的提高,以及GHB对混凝土抗高温损伤造成的积极影响.在此基础上,通过考虑热裂纹演化特征、GHB和硅灰的影响,建立了高温环境氯离子渗透性预测模型.

利用地基高分辨率傅里叶变换红外光谱技术探测大气氟氯烃气体CCl_(2)F_(2)的时空变化特征

大气二氯二氟甲烷(CCl_(2)F_(2),CFC-12)是人工合成的化学制剂,对平流层臭氧可产生严重的破坏和损耗.研究大气CFC-12的探测技术并获取其时空分布和变化,对了解区域氟氯烃气体变化趋势以及对平流层臭氧的影响具有重要意义.本文利用地基高分辨率傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)技术研究大气CFC-12的垂直分布和柱浓度的反演方法,基于最优估计算法反演2017-2020年合肥地区大气CFC-12的垂直廓线和柱总量.合肥大气CFC-12反演获得的垂直廓线表明,大气CFC-12在对流层以及低平流层处具有较高浓度,在垂直高度40 km以上浓度极低.合肥地区大气CFC-12的柱浓度含量呈现出夏季浓度较高,冬季与初春浓度较低的季节变化;观测期间大气CFC-12柱浓度呈现缓慢下降的趋势,年均变化率为-0.68%.将地基观测数据与ACE-FTS卫星观测数据进行比对,在高度范围16-28 km内两个CFC-12偏柱总量的相关性系数为0.73,可见地基和卫星数据具有较好的一致性.长期观测结果表明了地基高分辨率FTIR技术在观测大气中CFC-12的浓度垂直分布与季节变化上具有高的准确性和可靠性.

柔性植物影响下水沙运动及物质输运研究进展

水生植物是河流、湖泊、滨海湿地环境中不可缺少的一部分,植物的存在使水动力条件发生了改变,进而影响了泥沙悬浮和污染物的输运。从恒定流和波浪两种水动力条件出发,针对柔性植物影响下的水流阻力、水流结构、紊动特性、特征流速、消波系数、泥沙运动、污染物输运等方面,综述了国内外的主要成果,并指出复杂水动力条件下的植物-水流-泥沙-污染物之间的相互作用规律是今后研究的重点和难点。

Percutaneous nephrolithotomy for staghorn calculi: Troubleshooting and managing complications

Staghorn calculi comprise a unique subset of complex kidney stone disease. Percutaneousnephrolithotomy (PCNL) is the gold standard treatment for staghorn stones. Despitecontinuous refinements to the technique and instrumentation of PCNL, these stones remaina troublesome challenge for endourologists and are associated with a higher rate of perioperativecomplications than that for non-staghorn stones. Common and notable intraoperativecomplications include bleeding, renal collecting system injury, injury of visceral organs, pulmonarycomplications, thromboembolic complications, extrarenal stone migration, andmisplacement of the nephrostomy tube. Postoperative complications include infection and urosepsis,bleeding, persistent nephrocutaneous urine leakage, infundibular stenosis, and death.In this review, we report recommendations regarding troubleshooting measures that can beused to identify and characterize these complications. Additionally, we include informationregarding management strategies for complications associated with PCNL for staghorn calculi.

Overview of Physical and Chemical, Operational Properties of Nitrous Oxide Used as a Propellant for Low-thrust Rocket Engines

The results of a system analysis of the efficiency of nitrous oxide(N_2O) as a propellant component for small space vehicles(SSV) were presented. A criterion for mass efficiency of the SSV propulsion system(PS) is determined. The current global state-of-the-art of SSV PSs is shown. The application field of nitrous oxide in SSV PSs is calculated and mass efficiency of N_2O application is quantitatively determined. An overview of physical and chemical as well as operational properties of nitrous oxide as a promising, non-toxic component of rocket propellant is provided. Main physical and chemical constants of gaseous and liquid nitrous oxide; chemical properties of N_2O, thermal stability of N_2O, catalytic decomposition of N_2O, a mechanism of decomposition of N_2O, catalysts for decomposition of N_2O, ballast additives to N_2O, application of nitrous oxide, nitrous oxide as a rocket propellant, production of nitrous oxide, toxicity of nitrous oxide, fire hazard of N_2O, requirements to equipment when handling N_2O; storage and transportation of N_2O are considered. It is demonstrated that nitrous oxide is a chemical compound meeting the requirements to rocket propellants, including those related to the environmental friendliness of propellants. With 75 references.

Brief Review of N2O Decomposition Catalysts for Engines

A brief review of nitrous oxide decomposition catalysts was presented.The features of catalyst operating conditions in low-thrust engines of space vehicles and requirements to monopropellant(hydrogen peroxide,hydrazine,nitrous oxide)decomposition catalysts were considered.A scientific basis for development of a nitrous oxide decomposition catalyst and general principles for selection of efficient catalysts were formulated.The results of selecting catalyst systems for the development of decomposition catalysts for N2O as a monopropellant were presented.Preliminary selection of catalyst systems for the development of a catalyst designed for low-thrust rocket engines(LTREs)was carried out:supporter—Al2O3 and ZrO2;active substances—Co,Ni,Fe,Pd,Rh,Pt,Ru,Ir,NiO,Fe2O3,RuO2,Rh2O3,PdO,IrO2,PtO2,CoO,Al2O3,La2NiO4,Nd2NiO4,Pr 2NiO4,La2O3,TiO2,NiO,La2O3,TiO2,ZnO.With 71 references.

Discrimination of ventricular tachycardia and localization of its exit site using surface electrocardiography

Differential diagnosis of supraventricular tachycardia (SVT) and ventricular tachycardia (VT) is of paramount importance for appropriate patient management. Several diagnostic algorithms for discrimination of VT and SVT based on surface electrocardiogram (ECG) analysis have been proposed. Following established diagnosis of VT,a specific origination tachycardia site can be supposed according to QRS complex characteristics. This review aims to cover comprehensive and comparative description of the main VT diagnostic algorithms and to present ECG characteristics which permit to suggest the most common VT origination sites.

Progress and prospects of photocatalytic conversion of low-concentration NOx

NOx can cause severe environmental problems such as acid rain and photochemical smog,endangering human health and the living environment.Among them,NO pollution accounts for about 95%.NO can exist stably in the air for a long time when the concentration is lower than the ppm level.Therefore,the conversion of low concentration of NO has attracted more and more attention.However,traditional physical or chemical methods are difficult to deal with low concentration of NO,having high requirements on equipment and being not cost‐effective.Semiconductor photocatalytic technology can convert low concentration of NO into non‐toxic products and reduce its harm.This work briefly surveys the commonly used materials,modification methods,and mechanisms for semiconductor photocatalytic conversion of low concentration of NO.In addition,the challenges and prospects of ppb level of NO treatment are also discussed,aiming to promote the development of semiconductor photocatalytic conversion of NO.

Apatite U–Pb dating and geochemistry of the Kyrgyz South Tian Shan(Central Asia): Establishing an apatite fingerprint for provenance studies

This paper presents an apatite U-Pb and geochemistry archive for exposed plutons and metamorphic rocks of the Kyrgyz South Tian Shan(STS)within the Central Asian Orogenic Belt.Apatite U-Pb dates and trace-element geochemistry are provided for 17 samples from late Carboniferous-early Permian I-type granites in the Terktinsky complex and A-type granites in the Kokshaal Range;early Devonian granites in the Kembel complex;Cryogenian granitoids and tuffs from the Middle Tian Shan and gneisses from the Atbashi metamorphic complex.These samples form a comprehensive selection of igneous and metamorphic rocks within the cores of Mesozoic basement highs that supplied detritus to adjacent basins such as the Tarim,Ferghana and Yarkand-Ferghana Basins.Generally,the granitoid samples preserve primary igneous apatite U-Pb ages that are within uncertainty of previously published zircon U-Pb dates.The apatites from the Atbashi metamorphic complex record anomalous Ordovician dates with large uncertainties that are interpreted as mixing ages between Cryogenian protolith formation and Carboniferous metamorphism.Principal component analysis discriminates apatite samples from the different bedrock terranes in the Kyrgyz STS based on their geochemical fingerprint and categorizes the samples with respect to an extensive apatite geochemical archive.The combined apatite-zircon archive provides a novel framework for provenance studies on the Meso-Cenozoic sedimentary history of the Central Asian Orogenic Belt.

Improving nutrition for the prevention of gestational diabetes:Current status and perspectives

Gestational diabetes mellitus(GDM)is a common complication of pregnancy and a serious public health problem.It carries significant risks of short-term and longterm adverse health effects for both mothers and their children.Risk factors,especially modifiable risk factors,must be considered to prevent GDM and its consequences.Observational studies have identified several nutritional and lifestyle factors associated with the risk of GDM.The results of intervention studies examining the effects of diet and lifestyle on the prevention of GDM are contradictory.Differences in the study populations,types and intensity of intervention,time frame of the intervention,and diagnostic criteria for GDM may explain the heterogeneity in the results of intervention studies.This review provides an overview of new diets and other factors that may help prevent GDM.The main results of epidemiological studies assessing the risk factors for GDM,as well as the results and methodological problems of intervention studies on the prevention of GDM and their meta-analyses,are discussed.In addition,the evidence that gene and lifestyle interactions influence the development of GDM,as well as prospects for increasing the effectiveness of interventions designed to prevent GDM,including new data on the possible uses of personalized diet therapy,are highlighted.

20Cr3MoVW钢碳氮共渗热处理强化效应的XRD研究

介绍了利用XRD研究的20Cr3MoVW钢三种碳氮共渗热处理状态的显微组织,并计算了它们对强化的贡献。提出了采用XRD数据评估总屈服强度的方法,它基于多种显微组织强化机制线性叠加的钢强化模型。分析了渗层不同位置的预测屈服强度随热处理工艺的变化,并与硬化层中的显微硬度分布作了对比。

Modeling the Vertical Distribution of the Milky Way’s Flat Subsystem Objects

This paper is an initial stage of consideration of the general problem of joint modeling of the vertical structure of a Galactic flat subsystem and the average surface of the disk of the Galaxy,taking into account the natural and measurement dispersions.We approximate the average surface of the Galactic disk in the region covered by the data with a general(polynomial)model and determine its parameters by minimizing the squared deviations of objects along the normal to the model surface.The smoothness of the model,i.e.,its order n,is optimized.An outlier elimination algorithm is applied.The developed method allows us to simultaneously identify significant details of the Galactic warping and estimate the offset z_(⊙) of the Sun relative to the average(in general,non-flat)surface of the Galactic disk and the vertical scale of the object system under consideration for an arbitrary area of the disk covered by data.The method is applied to data on classical Cepheids.Significant local extremes of the average disk surface model were found based on Cepheid data:the minimum in the first Galactic quadrant and the maximum in the second.A well-known warp(lowering of the disk surface)in the third quadrant has been confirmed.The optimal order of the model describing all these warping details was found to be n_(o)=4.The local(for a small neighborhood of the Sun,n_(o)=0)estimate of z_(⊙)=28.1±6.1|_(stat).±1.3|_(cal).pc is close to the non-local(taking into account warping,n_(o)=4)z_(⊙)=27.1±8.8|_(stat.-1.2)^(+1.3)|_(cal).pc(statistical and calibration uncertainties are indicated),which suggests that the proposed modeling method eliminates the influence of warping on the z_(⊙) estimate.However,the non-local estimate of the vertical standard deviation of Cepheids σ_(p)=132.0±3.7|_(stat.-5.9)^(+6.3)|_(cal).pc differs significantly from the local σ_(ρ)=76.5±4.4|_(stat.-3.4)^(+3.6)|_(cal).pc,which implies the need to introduce more complex models for the vertical distribution outside the Sun’s vicinity.