Hydro-Chemical Processes in Lake Qinghai throughout Climate Warming: In Situ Investigations of the Largest Lake in China

In the wake of climate warming, the water level of Lake Qinghai has been continuously and rapidly declining during the past decades, causing the regional government and citizens to worry about its future as a water resource. To understand the lake evolution process, the hydro-chemical characteristics of Lake Qinghai were investigated in August of 2008. The results show that Na+ and Cl- are the dominant cations and anions in the lake water, respectively, and hydrochemistry type is Cl-- Na+ with an obvious characteristic of a saline lake. The Gibbs plot illuminates that evaporation/crystallization is responsible for the chemical composition of the lake water. The variation in hydro-chemical regime might be attributed to the reduced lake levels between 1960s and 2000s. The lake level significantly correlated with the precipitation and evaporation in the Lake Qinghai catchment. In addition, changes of the lake level in the future are simulated according to climate warming scenarios from the IPCC report. The simulated results suggest that the lake level could rise again in the following decades due to the increased precipitation under the climate warming conditions, which is already a trend in the lake level observation data.

Boron isotope geochemistry of Zigetang Co saline lake sediments,Tibetan Plateau

The origin of boron in boron-rich salt lakes in the Tibetan Plateau is highly controversial.In this study,we carried out a detailed study on boron geochemistry and isotope composition of lake sediments collected in Zigetang Co,central Tibet.Evaporites had high boron concentrations of 172.3–418.6 lg/g and δ^(11)B values of-8.2%to-3.3%,suggesting a non-marine origin for the saline lake.The boron isotopic fractionation factor,a,between evaporite and brackish water(a_(evaporite–brackish))decreased systematically with depth,from 0.9942 at the top of the drill core to 0.9893 at the bottom;the linear variation between α_(evaporite–brackish)and depth reflects boron isotopic fractionation associated with progressive crystallization.The positive correlation between δ^(11)B versus[B]and δ^(11)B versus depth in the evaporite phase reflects pH and boron speciation in the solution control on the adsorption of boron,and B(OH)_3 species incorporated preferentially into Mg(OH)_2 precipitation at high pH.

A Fast and Accurate LEO Satellite-Based Direct Position Determination Assisted by TDOA Measurements

This paper focuses on the trusted vessel position acquisition using passive localization based on the booming low-earth-orbit(LEO) satellites. As the high signal-to-noise ratio(SNR) reception cannot always be guaranteed at LEO satellites, the recently developed direct position determination(DPD)is adopted. For LEO satellite-based passive localization systems, an efficient DPD is challenging due to the excessive exhaustive search range leading from broad satellite coverage. In order to reduce the computational complexity, we propose a time difference of arrival-assisted DPD(TA-DPD) which minimizes the searching area by the time difference of arrival measurements and their variances. In this way, the size of the searching area is determined by both geometrical constraints and qualities of received signals, and signals with higher SNRs can be positioned more efficiently as their searching areas are generally smaller.Both two-dimensional and three-dimensional passive localization simulations using the proposed TA-DPD are provided to demonstrate its efficiency and validity. The superior accuracy performance of the proposed method, especially at low SNRs conditions, is also verified through the comparison to conventional two-step methods. Providing a larger margin in link budget for satellite-based vessel location acquisition,the TA-DPD can be a competitive candidate for trusted marine location service.

Development of covalent-organic frameworks derived hierarchical porous hollow carbon spheres based LiOH composites for thermochemical heat storage

Under the joint assistance of its excellent storage strength, accessible long storage lifespan, and high heat utilization efficiency, salt hydrate-based thermochemical heat storage(THS) materials give renewable energy an important outlet to alleviate the pressure of underutilization. Herein, an activated hollow spherical carbon(AHSC) with hierarchical porous architectures converted from covalent-organic frameworks(COFs) is constructed and utilized as the supporting matrix for Li OH.THS composite material for the first time. The obtained Li/AHSC_(3) composites have distinguished hydration performance while manifesting impressive storage ability up to 1916.4 k J kg^(-1)with low operating temperature stemming from the collective effect of the void spherical framework, multimodal porosity, and high surface area of AHSC3. And the Li/AHSC3-40 composite with evidently progressed thermal conductivity is capable of realizing 94.5% heat preservation after twenty-five adsorption-desorption cycles, exhibiting its eminent cyclability and great heat transfer performance. This study not only brings new hope for overcoming the underutilization of low-grade heat but also may enlighten new ideas for enriching the application scenarios of COFs-derived carbonaceous materials.

Effects of Porous Graphene on LiOH Based Composite Materials for Low Temperature Thermochemical Heat Storage

Thermochemical heat storage material inorganic hydrate LiOH is selected as a promising candidate material for storing low-temperature heat energy because of its high energy density(1440 kJ/kg)and mild reaction process.However,the low hydration rate of LiOH limits the performance of low temperature thermochemical heat storage system as well as the thermal conductivity.In this study,porous-graphene/LiOH composite thermochemical heat storage materials with strong water sorption property and higher thermal conductivity were synthesized by hydrothermal process.The experimental results show that the hydration rate of the composites was greatly improved.The heat storage density of the composite materials was increased by 47%(from 661 kJ/kg to 974 kJ/kg).By combing the porous graphene,the thermal conductivity of composites with different contents were highly increased by 21.1%to 78.7%,but the increase of heat storage density is opposite to that of thermal conductivity.The development of high-performance materials for thermochemical heat storage should consider the relationship between the heat storage density and thermal conductivity of the material,and the thermal conductivity of the supporter needs to be further improved.

Long-Term Durability and Reactivation of Thermochemical Heat Storage Driven by the CaO/Ca(OH)₂Reversible Reaction

Thermochemical heat storage is a promising technology for improving thermal energy efficiency. To investigate the durability of the CaO/Ca(OH)2 reaction and develop a reactivation method, repetitive charging/discharging operation of a packed bed reactor with a thick packed bed was conducted, and variations in the discharging behavior, final conversion, and reactant activity were investigated. Owing to the formation of a deactivated sintered reactant block, the discharging time halved and the final conversion ratio decreased by the 53rd discharging operation. To enhance durability, a reactivation method using high-pressure vapor was implemented during the 54th discharging operation. Following reactivation, the final conversion increased 15%, and the discharging time tripled when compared with the discharging operation before reactivation, confirming the success of this simple reactivation method.

Optimal Batching Plan of Deoxidation Alloying based on Principal Component Analysis and Linear Programming

As the market competition of steel mills is severe,deoxidization alloying is an important link in the metallurgical process.To solve this problem,principal component regression analysis is adopted to reduce the dimension of influencing factors,and a reasonable and reliable prediction model of element yield is established.Based on the constraint conditions such as target cost function constraint,yield constraint and non-negative constraint,linear programming is adopted to design the lowest cost batting scheme that meets the national standards and production requirements.The research results provide a reliable optimization model for the deoxidization and alloying process of steel mills,which is of positive significance for improving the market competitiveness of steel mills,reducing waste discharge and protecting the environment.

新型MIL-101(Fe)/BiOBr S型异质催化剂用于高效光催化降解抗生素和还原六价铬:光催化性能分析和光催化机理研究

水污染对生态环境和人类健康造成了巨大危害,特别是水体中抗生素和重金属具有毒性且难生物降解,已经引起科研工作者的广泛关注.传统的水处理技术难以有效地消除这些污染物.近年来,人们致力于开发绿色、低碳且高效的光催化技术用于解决环境污染问题,该技术实现大规模应用的核心在于开发出经济、高效的光催化剂.由于单一半导体光催化材料(如BiOBr)存在一些缺陷(如有限的催化活性位点和光生电子-空穴快速复合等),因此,构建具有可见光响应、高暴露活性位点和强氧化还原能力的异质结特别是新兴的梯(S)型异质结是去除这些污染物的有效策略之一.MIL-101(Fe)是一种新型的可见光驱动的金属-有机配体框架材料,具有强还原活性、高比表面积和较好的可见光吸收能力,因此,将氧化型的Bi OBr与还原型的MIL-101(Fe)进行合理设计,构筑S型异质结,有望开发出高效的催化材料.本文采用溶剂热法成功制备了一种新型的MOF基S型异质结MIL-101(Fe)/BiOBr,用于可见光照射下光催化还原六价铬(Cr(Ⅵ))和降解抗生素恩诺沙星.结果表明,在单一污染物体系中,MIL-101(Fe)/BiOBr可有效还原99.4%的Cr(Ⅵ)和氧化分解84.4%的恩诺沙星.值得注意的是,在Cr(Ⅵ)和恩诺沙星共存的条件下,MIL-101(Fe)/BiOBr对(Cr(Ⅵ))和恩诺沙星的去除效率明显提升,这主要是由于S型催化剂、Cr(Ⅵ)和恩诺沙星之间具有协同效应.MIL-101(Fe)/BiOBr催化剂活性增强的主要因素如下:(1)MIL-101(Fe)提供了大量的活性位点,改善了催化材料的光吸收能力.(2)S型载流子分离路径不但促进了电子和空穴的高效分离,而且增强了体系的氧化还原能力.此外,采用自由基捕获实验、电子自旋共振波谱仪、液相色谱-质谱联用技术以及毒性分析软件,系统分析了光催化反应机理、抗生素分解过程和中间产物的生物毒性.综上,本文提供一种简单有效的策略来构筑高活性的MOF/无机半导体S型异质结材料用于高效净化水体环境.

层间化学键合促进二维层状共价有机框架光催化析氢

As an alternative clean energy carrier to replace traditional fossil energy,hydrogen energy has been the focus of numerous studies1.Direct conversion of water into hydrogen becomes a sustainable protocol2,3.Many photocatalysts,including organic and inorganic semiconductors,suffer from problems of narrow light absorption,poor charge separation,and insufficient active site4-6.These factors severely limit their practical applications.

虚拟支气管镜导航联合支气管超声导向鞘引导肺活检术在肺周围性病变诊断中的应用

背景与目的虚拟支气管镜导航(virtual bronchoscopic navigation, VBN)联合支气管超声导向鞘技术(endobronchial ultrasonography with guide sheath, EBUS-GS)用于经支气管肺活检术(transbronchus lung biopsy,TBLB),能够减少甚至避免射线暴露。本研究拟评价VBN联合EBUS-GS对肺周围性病变(pulmonaryperipheral lesions,PPLs)的诊断价值及安全性。方法回顾性分析2016年1月-2017年12月在北京大学肿瘤医院内镜中心接受EBUS-GS-TBLB患者的临床病理资料,评价诊断率及安全性,并对影响诊断率的因素进行分析。结果 121例患者纳入本研究,男性65例,女性56例;平均年龄(58.8±10.3)岁。108例(89.3%)可在EBUS图像中显示,共有89例(73.5%)经EBUS-GS-TBLB获得明确诊断。EBUS-GS-TBLB对恶性病变的诊断率为82.5%。联合刷检、活检及肺泡灌洗中两种或三种方式取检的诊断率(87.2%)高于仅采用单一方式取检(58.8%)(χ~2=6.084, P=0.014)。影响EBUSGS-TBLB诊断率的因素包括超声探头位于病灶内部(χ~2=20.372,P=0.000)、病灶位于肺野内带及中带(χ~2=10.810,P=0.001)。1例(0.8%)患者术中出血量较多。结论 VBN联合EBUS-GS-TBLB是一种诊断PPLs安全且有效的方法。

Research on the navigational risk of liquefied natural gas carriers in an inland river based on entropy:A cloud evaluation model

Due to the flammability and explosive nature of liquefied natural gas(LNG),an extremely strict process is followed for the transporta-tion of LNG carriers in China.Particularly,no LNG carriers are operating in inland rivers within the country.Therefore,to ensure the future navigation safety of LNG carriers entering the Yangtze River,the risk sources of LNG carriers’navigation safety must be identi-fied and evaluated.Based on the Delphi and expert experience method,this paper analyses and discusses the navigation risk factors of LNG carriers in the lower reaches of the Yangtze River from four aspects(human,ship,environment and management),identifies 12 risk indicators affecting the navigation of LNG carriers and establishes a risk evaluation index system.Further,an entropy weight fuzzy model is utilized to reduce the influence of subjective judgement on the index weight as well as to conduct a segmented and overall evaluation of LNG navigation risks in the Baimaosha Channel.Finally,the cloud model is applied to validate the consistent feasibility of the entropy weight fuzzy model.The research results indicate that the method provides effective technical support for further study on the navigation security of LNG carriers in inland rivers.

Zr（HPO4）2/浇铸尼龙6复合材料的制备及结晶性能

采用原位聚合法制备磷酸氢锆/浇铸尼龙6(Zr(HPO4)2/MCPA6)复合材料。X射线衍射和差示扫描量热研究表明,当Zr(HPO4)2的质量分数为1.5%时,复合材料的结晶度由纯MCPA6的15.1%增加到22.2%,少量的Zr(HPO4)2对复合材料能起到结晶成核剂的作用,诱导γ(200)晶型的产生;偏光显微镜对复合材料等温结晶的观察进一步验证了上述对复合材料结晶度表征的结果。摆锤冲击试验和热重分析显示,随着Zr(HPO4)2的加入,复合材料的冲击强度和热稳定性有所增加。

新型氮氧化钽/氧空位钨酸铋S型异质结纤维用于高效光催化降解抗生素和还原六价铬:产物毒性分析和光催化机理研究

近年来,环境污染问题严重地威胁着人类的生存和健康.半导体光催化是一种绿色环保的治理环境污染技术,该技术实现大规模应用的关键在于构建高效的光催化剂.TaON因优异的光电性质、稳定的物理化学性质及适合的能带结构等优势,被广泛应用于光催化水裂解和有害污染物降解等领域.但光生载流子快速复合和比表面积小等问题严重制约了其大规模应用.近年来,人们发现构建新型S型异质结能有效促进光生电子和空穴分离,同时充分保存具有强氧化还原能力的电子和空穴,进而有效提升材料的光催化性能.因此,通过构建新型TaON S型异质结光催化材料有f望开发出高效的可见光光催化体系.本文采用静电纺丝-煅烧-氮化工艺制备出由纳米颗粒组成的多孔TaON纳米纤维,然后采用溶剂热法制得一系列富含氧空位的TaON/Bi_(2)WO_(6) S型异质结纤维,并用于可见光照射下光催化降解抗生素和还原Cr^(6+).实验发现,富含氧空位的Bi_(2)WO_(6)二维纳米片均匀生长在TaON纳米纤维上形成了良好的1D/2D核壳结构,此异质结界面结构有利于界面间电荷的分离和传输.当TaON/Bi_(2)WO_(6)质量比为20 wt%时,在可见光下分别照射50,60和50 min,20 mg复合纤维可降解93.2%的四环素溶液(20 mg/L,100 mL,pH=5.2),83.7%的左氧氟沙星溶液(20 mg/L,100 mL,pH 6.7)以及还原95.6%的Cr^(6+)溶液(10 mg/L,100 mL,pH=2.5),其对三种污染物的去除速率分别是纯Bi_(2)WO_(6)的3.8,2和2.9倍,且远高于纯TaON纤维.此外,该复合纤维具有良好的矿化能力及循环稳定性,在实际废水中依然表现出较好的催化降解活性.表征结果表明,复合纤维光催化活性增强是由于TaON与Bi_(2)WO_(6)之间形成了S型的异质结,并富含氧空位;在内电场,能带弯曲和库仑力的协同作用下,实现了强氧化还原能力的电子和空穴的高效分离和保存,有效提升了体系的光催化性能.综上,本文采用缺陷工程结合异质构筑策略有效地提升了体系的光催化活性,为开发高效的光催化体系提供一定的参考.

蒙脱土改性超支化聚酰胺6纳米复合材料的结晶与流变性能

采用原位聚合法制备超支化聚酰胺6(PA6)/蒙脱土(MMT)纳米复合材料。利用自动黏度仪、傅里叶变换红外光谱仪、热重分析仪、差示扫描量热仪、X射线衍射仪、毛细管流变仪、力学万能试验机等对超支化PA6/蒙脱土纳米复合材料进行表征。研究表明,上述复合材料的剪切黏度与剪切速率流变曲线符合幂律流体的特征,便于成型加工;复合材料晶型(α、γ)在加入MMT后没有发生变化,结晶度由纯超支化PA6的36.49%降低至33.54%;另外,随着MMT加入基体,纳米复合材料的热稳定性、拉伸强度、断裂伸长率和冲击强度显著增加。

Effects of confining pressure on acoustic emission and failure characteristics of sandstone

In this study,uniaxial and triaxial compression acoustic emission(AE)tests were implemented to investigate the AE effect and failure characteristics of sandstone under different confining pressures(σ3).The evolution of AE parameters in the rock failure process and fracture fractal dimension characteristics after failure were analyzed.The results revealed that the activity of the AE signal is strongly related toσ3.The evolution of the Ib value can be divided into the I-fluctuation,II-stability,and III-decrease stages.In the first stage,the Ib value of the AE was relatively high,and the AE energy was low.Then,the Ib value tended to be stable;however,the fluctuation amplitude decreased,and the AE energy rapidly increased.In the stage of decrease,the AE energy sharply increased before the load approached the peak value,and the Ib value significantly decreased and dropped to the lowest point before the peak value.Asσ3 increased,the rock’s failure mode changed from tensile failure to shear failure and became more coordinated.As the confining pressure increased,the shape dimension decreased,and the order degree of rock failure increased.The confining pressure exerted a certain control effect on the rock failure.

Virtual bronchoscopic navigation without fluoroscopy guidance for peripheral pulmonary lesions in inexperienced pulmonologist

Objective:Fluoroscopy guidance is generally required for endobronchial ultrasonography with guide sheath(EBUS-GS)in peripheral pulmonary lesions(PPLs).Virtual bronchoscopic navigation(VBN)can guide the bronchoscope by creating virtual images of the bronchial route to the lesion.The diagnostic yield and safety profiles of VBN without fluoroscopy for PPLs have not been evaluated in inexperienced pulmonologist performing EBUS-GS.Methods:Between January 2016 and June 2017,consecutive patients with PPLs referred for EBUS-GS at a single cancer center were enrolled.The diagnostic yield as well as safety profiles was retrospectively analyzed,and our preliminary experience was shared.Results:A total of 109 patients with 109 lesions were included,99(90.8%)lesions were visible on EBUS imaging.According to the procedure time needed to locate the lesion on EBUS,24.8%(27/109)were deemed technically difficult procedures;however,no significant relationships were identified between candidate parameters and technically difficult procedures.The overall diagnosis yield was 74.3%(81/109),and the diagnostic yield of malignancy was 83.7%(77/92).Lesions larger than 20 mm[odds ratio(OR),2.758;95%confidence interval(95%CI),1.077-7.062;P=0.034]and probe of within type(OR,3.174;95%CI,1.151-8.757,P=0.026)were independent factors leading to a better diagnostic yield in multivariate analysis.About 30 practice procedures were needed to achieve a stable diagnostic yield,and the proportion of technically difficult procedures decreased and stabilized after 70 practice procedures.Regarding complications,one patient(0.9%)had intraoperative hemorrhage(100 mL)which was managed under endoscopy.Conclusions:VBN without fluoroscopy guidance is still useful and safe for PPLs diagnosis,especially for malignant diseases when performed by pulmonologist without previous experience of EBUS-GS.VBN may simplify the process of lesion positioning and further multi-center randomized studies are warranted.

Ta_(3)N_(5)/CdS Core–Shell S‑scheme Heterojunction Nanofibers for Efficient Photocatalytic Removal of Antibiotic Tetracycline and Cr(VI):Performance and Mechanism Insights

Ta_(3)N_(5)/CdS core–shell S-scheme heterojunction nanofibers are fabricated by in situ growing CdS nanodots on Ta_(3)N_(5) nanofib-ers via a simple wet-chemical method.These Ta_(3)N_(5)/CdS nanofibers not only affords superior photocatalytic tetracycline degradation and mineralization performance,but also cause an efficient photocatalytic Cr(VI)reduction performance.The creation of favorable core–shell fiber-shaped S-scheme hetero-structure with tightly contacted interface and the maximum interface contact area promises the effective photo-carrier disintegration and the optimal photo-redox capacity synchronously,thus leading to the preeminent photo-redox ability.Some critical environmental factors on the photo-behavior of Ta_(3)N_(5)/CdS are also evaluated in view of the complexity of the authentic aquatic environment.The degradation products of tetracycline were confirmed by HPLC–MS analyses.Furthermore,the effective decline in eco-toxicity of TC intermediates is confirmed by QSAR calculation.This work provides cutting-edge guidelines for the design of high-performance Ta_(3)N_(5)-based S-scheme heterojunction nanofibers for environment restoration.

A novel double dielectric barrier discharge reactor with high field emission and secondary electron emission for toluene abatement

Dielectric barrier discharge(DBD)has been extensively investigated in the fields of environment and energy,whereas its practical implementation is still limited due to its unsatisfactory energy efficiency.In order to improve the energy efficiency of DBD,a novel double dielectric barrier discharge(NDDBD)reactor with high field emission and secondary electron emission was developed and compared with traditional DDBD(TDDBD)configuration.Firstly,the discharge characteristics of the two DDBD reactors were analyzed.Compared to TDDBD,the NDDBD reactor exhibited much stronger discharge intensity,higher transferred charge,dissipated power and gas temperature due to the effective utilization of cathode field emission and secondary electron emission.Subsequently,toluene abatement performance of the two reactors was evaluated.The toluene decomposition efficiency and mineralization rate of NDDBD were much higher than that of TDDBD,which were 86.44%-100%versus 28.17%-80.48%and 17.16%-43.42%versus 7.17%-16.44%at 2.17-15.12 W and 1.24-4.90 W respectively.NDDBD also exhibited higher energy yield than TDDBD,whereas the overall energy constant k_(overall)of the two reactors were similar.Finally,plausible toluene decomposition pathway in TDDBD and NDDBD was suggested based on organic intermediates that generated from toluene degradation.The finding of this study is expected to provide reference for the design and optimization of DBD reactor for volatile organic compounds control and other applications.

Magnetic Wakame-Based Biochar/Ni Composites with Enhanced Adsorption Performance for Diesel

In this study,the magnetic wakame biochar/Ni composites were prepared with three activating reagents of H_(3)PO_(4),ZnCl_(2) and KOH by one-step pyrolysis activation,characterized by BET,SEM,TEM,FI-IR,XRD,Raman,and elemental analyzer,and their adsorption performance for diesel were also analyzed.The results showed that wakame biochar/Ni composites had larger specific surface area,abundant porous structure,and various reactive groups,rendering its enhancement of adsorption efficiency.The adsorption experiments indicated that the maximum adsorption capacities for diesel using WBPA 0.5,WBHZ 0.5 and WBPH 0.5 were 4.11,8.83,and 13.47 g/g,respectively.The Langmuir model was more suitable for the adsorption isotherms process,and the Pseudo-second-order model could better describe the adsorption kinetic experimental.And the magnetic wakame biochar/Ni composites presented good stability and recyclability.This study provides a novel pattern for the high-value utilization of wakame,having huge potential in the treatment of oily wastewater.