Analysis of a landfill cover without geomembrane using varied particle sizes of recycled concrete

Previous studies have demonstrated the effectiveness of a novel three-layer landfill cover system constructed with recycled concrete aggregates(RCAs)without geomembrane in both laboratory and field.However,no systematic investigation has been carried out to optimize the combination of the particle sizes for fine-grained RCAs(FRC)and coarse-grained RCAs(CRC)that can be used for the three-layer landfill cover system.The aim of this paper is to assist engineers in designing the three-layer landfill cover system under a rainfall of 100-year return period in humid climate conditions using an easily controlled soil parameter D10 of RCAs.The numerical study reveals that when D10 of FRC increases from 0.05 mm to 0.16 mm,its saturated permeability increases by 10 times.As a result,a larger amount of rainwater infiltrates into the cover system,causing a higher lateral diversion in both the top FRC and middle CRC layers.No further changes in the lateral diversion are observed when the D10 value of FRC is larger than 0.16 mm.Both the particle sizes of FRC and CRC layers are shown to have a minor influence on the percolation under the extreme rainfall event.This implies that the selection of particle sizes for the FRC and CRC layers can be based on the availability of materials.Although it is well known that the bottom layer of the cover system should be constructed with very fine-grained soils if possible,this study provides an upper limit to the particle size that can be used in the bottom layer(D10 not larger than 0.02 mm).With this limit,the three-layer system can still minimize the water percolation to meet the design criterion(30 mm/yr)even under a 100-year return period of rainfall in humid climates.

Mechanical properties of dredged soil reinforced by xanthan gum and fibers

Biopolymers have become popular in geotechnical engineering as they provide a carbon-neutral alternative for soil solidification.Xanthan gum(XG)and jute fiber(JF)were selected to solidify the Yellow River dredged soil.The mechanical behavior of solidified dredged soil(SDS)was investigated using a series of uniaxial compression and splitting tension tests at different XG and JF contents and fiber lengths.The results indicate that on the 28th day,the unconfined compressive strength(UCS)values of SDS samples reached 2.83 MPa and splitting tensile strength(STS)of 0.763 MPa at an XG content of 1.5%.When the JF content was greater than 0.9%,the STS of the SDS samples decreased.This is because that the large fiber content weakened the cementation ability of XG.The addition of JF can significantly increase the strain at peak strength of SDS samples.There is a linear relationship between the UCS and STS of the dredged soils solidified by XG and JF.Microanalysis shows that the strength of SDS samples was improved mainly via the cementation of XG itself and the network structure formed by JF with soil particles.The dredged soil reinforced by XG and JF shows better mechanical performance and has great potential for application.

Fault Current Identification of DC Traction Feeder Based on Optimized VMD and Sample Entropy

A current identification method based on optimized variational mode decomposition(VMD)and sample entropy(SampEn)is proposed in order to solve the problem that the main protection of the urban rail transit DC feeder cannot distinguish between train charging current and remote short circuit current.This method uses the principle of energy difference to optimize the optimal mode decomposition number k of VMD;the optimal VMD for DC feeder current is decomposed into the intrinsic modal function(IMF)of different frequency bands.The sample entropy algorithm is used to perform feature extraction of each IMF,and then the eigenvalues of the intrinsic modal function of each frequency band of the current signal can be obtained.The recognition feature vector is input into the support vector machine model based on Bayesian hyperparameter optimization for training.After a large number of experimental data are verified,it is found that the optimal VMD_SampEn algorithm to identify the train charging current and remote short circuit current is more accurate than other algorithms.Thus,the algorithm based on optimized VMD_SampEn has certain engineering application value in the fault current identification of the DC traction feeder.

A comprehensive review of azadirachtin: physicochemical properties, bioactivities, production, and biosynthesis

Azadirachtin,a complex tetratriterpenoid limonin with potent insecticidal properties,is the most widely used biological pesticide worldwide.Its versatile pharmacological applications include the inhibition of tumor growth and anti-malarial,anti-bacterial,and anti-inflammatory properties.Azadirachtin plays a pivotal role in pest control and novel drug development.The primary source of azadirachtin is the neem tree(Azadirachta indica A.Juss),with an azadirachtin content ranging from 0.3%to 0.5%.Despite the market demand for botanical pesticides reaching approximately 100,000 tons per year,the annual neem production in China is only 1.14 tons.Although azadirachtin can be obtained through plant extraction or chemical synthesis,the quantity obtained does not meet the market demand in China.The sluggish pace of azadirachtin biosynthesis results from the limited availability of genetic information and the complexity of the synthetic pathway.Recent advancements in azadirachtin biosynthesis hold promise as an efficient collection method.In this study,we explored the physicochemical properties,biological activities,mechanisms of action,and acquisition methods of azadirachtin.We also delved into recent progress in azadirachtin biosynthesis and assessed potential future usage challenges.This study aims to establish a theoretical foundation for the scientific application and efficient synthesis of azadirachtin,offering valuable reference information to the industry.

Robust Attitude Control for Reusable Launch Vehicles Based on Fractional Calculus and Pigeon-inspired Optimization

In this paper, a robust attitude control system based on fractional order sliding mode control and dynamic inversion approach is presented for the reusable launch vehicle RLV during the reentry phase. By introducing the fractional order sliding surface to replace the integer order one, we design robust outer loop controller to compensate the error introduced by inner loop controller designed by dynamic inversion approach. To take the uncertainties of aerodynamic parameters into account, stochastic robustness design approach based on the Monte Carlo simulation and Pigeon-inspired optimization is established to increase the robustness of the controller. Some simulation results are given out which indicate the reliability and effectiveness of the attitude control system. © 2014 Chinese Association of Automation.

虚拟仿真在物化实验教学中的应用

针对目前实验教学模式,以经典物理化学实验原电池电动势的测定作为研究对象,设计了一个基于Lab VIEW的虚拟仿真实验系统。该系统不仅高度仿真原电池电动势的测定实验的全过程,还加入了实验步骤操作提示和错误警示设计。与传统教学模式相比,采用线上线下混合教学模式,学生实验所用时间平均缩短20分钟左右,且60%左右的学生实验误差的绝对值在5%以内。

Puerarin exhibits greater distribution and longer retention time in neurons than astrocytes in a co-cultured system

The phytoestrogen puerarin has been shown to protect neurons and astrocytes in the brain, and is therefore an attractive drug in the treatment of Alzheimer’s disease, Parkinson’s disease and cerebral ischemia. Whether puerarin exhibits the same biological processes in neurons and astro-cytesin vitro has rarely been reported. In this study, cortical neurons and astrocytes of newborn Sprague-Dawley rats were separated, identiifed and co-cultured in a system based on Transwell membranes. The retention time and distribution of puerarin in each cell type was detected by lfuorescence spectrophotometry and lfuorescence microscope. The concentration of puerarin in both co-cultured and separately cultured neurons was greater than that of astrocytes. Puerarin concentration reached a maximum 20 minutes after it was added. At 60 minutes after its addi-tion, a scant amount of drug was detected in astrocytes; however in both separately cultured and co-cultured neurons, the concentration of puerarin achieved a stable level of about 12.8 ng/mL. The results indicate that puerarin had a higher concentration and longer retention time in neu-rons than that observed in astrocytes.

Mechanism of the December 2015 Catastrophic Landslide at the Shenzhen Landfill and Controlling Geotechnical Risks of Urbanization

This paper presents findings from an investigation of the large-scale construction solid waste （CSW） landslide that occurred at a landfill at Shenzhen, Guangdong, China, on December 20, 2015, and which killed 77 people and destroyed 33 houses. The landslide involved 2.73 - 106 m3 of CSW and affected an area about 1100 m in length and 630 m in maximum width, making it the largest landfill landslide in the world. The investigation of this disaster used a combination of unmanned aerial vehicle surveillance and multistage remote-sensing images to reveal the increasing volume of waste in the landfill and the shifting shape of the landfill slope for nearly two years before the landslide took place, beginning with the creation of the CSW landfill in March, 2014, that resulted in the uncertain conditions of the landfill＇s boundaries and the unstable state of the hydrologic performance. As a result, applying conventional stability analysis methods used for natural landslides to this case would be difficult. In order to analyze this disaster, we took a multistage modeling technique to analyze the varied characteristics of the land- fill slope＇s structure at various stages of CSW dumping and used the non-steady flow theory to explain the groundwater seepage problem. The investigation showed that the landfill could be divided into two units based on the moisture in the land： （1） a front uint, consisted of the landfill slope, which had low water content; and （2） a rear unit, consisted of fresh waste, which had a high water content. This struc- ture caused two effects-surface-water infiltration and consolidation seepage that triggered the landslide in the landfill. Surface-water infiltration induced a gradual increase in pore water pressure head, or piezometric head, in the front slope because the infiltrating position rose as the volume of waste placement increased. Consolidation seepage led to higher excess pore water pressures as the loading of waste increased. We also investigated the post-failure soil dynamics parameters of the landslide deposit using cone penetration, triaxial, and ring-shear tests in order to simulate the characteristics of a flowing slide with a long run-out due to the liquefaction effect. Finally, we conclude the paper with lessons from the tens of catastrophic landslides of municipal solid waste around the world and discuss how to better manage the geotechnical risks of urbanization.

Machine learning approach to predict acute kidney injury after liver surgery

BACKGROUND Acute kidney injury(AKI)after surgery appears to increase the risk of death in patients with liver cancer.In recent years,machine learning algorithms have been shown to offer higher discriminative efficiency than classical statistical analysis.AIM To develop prediction models for AKI after liver cancer resection using machine learning techniques.METHODS We screened a total of 2450 patients who had undergone primary hepatocellular carcinoma resection at Changzheng Hospital,Shanghai City,China,from January 1,2015 to August 31,2020.The AKI definition used was consistent with the Kidney Disease:Improving Global Outcomes.We included in our analysis preoperative data such as demographic characteristics,laboratory findings,comorbidities,and medication,as well as perioperative data such as duration of surgery.Computerized algorithms used for model development included logistic regression(LR),support vector machine(SVM),random forest(RF),extreme gradient boosting(XGboost),and decision tree(DT).Feature importance was also ranked according to its contribution to model development.RESULTS AKI events occurred in 296 patients(12.1%)within 7 d after surgery.Among the original models based on machine learning techniques,the RF algorithm had optimal discrimination with an area under the curve value of 0.92,compared to 0.87 for XGBoost,0.90 for DT,0.90 for SVM,and 0.85 for LR.The RF algorithm also had the highest concordance-index(0.86)and the lowest Brier score(0.076).The variable that contributed the most in the RF algorithm was age,followed by cholesterol,and surgery time.CONCLUSION Machine learning algorithms are highly effective in discriminating patients at high risk of developing AKI.The successful application of machine learning models may help guide clinical decisions and help improve the long-term prognosis of patients.

Engineering and microstructure properties of contaminated marine sediments solidified by high content of incinerated sewage sludge ash

Management of incinerated sewage sludge ash(ISSA)and dredged contaminated marine sediments(CMSs)is a great challenge for Hong Kong and other coastal cities due to limited landfilling capacity.The present study investigates the use of high content(20%of sediment by mass)of ISSA in combination with cement/lime for solidification/stabilization(S/S)treatment of CMSs to provide a way to reuse the wastes as construction materials.The results showed that ISSA being a porous material was able to absorb a large amount of water rendering a more efficient solidification process of the marine sediment which normally had a very high water content(w80%).The S/S treatment improved the engineering properties of the sediment,but reduced the workability,especially for the lime-treated samples.Lime can be used to replace ordinary Portland cement(OPC)for better heavy metal immobilization and carbon emission reduction.The hardened sediment samples prepared with 10%of lime and 20%of ISSA could attain a strength of 1.6 MPa after 28 d of curing.In addition,leaching tests confirmed that there was no environmental risk induced by these stabilized materials.The formation of hydrated cementitious compounds including calcium silicate hydrate(CeSeH)/calcium aluminate silicate hydrate(C-A-S-H)/hydrocalumite/calcite was mainly responsible for the strength development in the ISSA/lime-treated sediments.

Effects of extended lymphadenectomy and postoperative chemotherapy on node-negative gastric cancer

AIM:To investigate the effects of extended lymphadenectomy and postoperative chemotherapy on gastric cancer without lymph node metastasis.METHODS:Clinical data of 311 node-negative gastric cancer patients who underwent potentially curative gastrectomy with more than 15 lymph nodes resected,from January 2002 to December 2006,were analyzed retrospectively.Patients with pT4 stage or distant metastasis were excluded.We analyzed the relationship between the D2 lymphadenectomy and the 5-year survival rate among different subgroups stratified by clinical features,such as age,tumor size,tumor location and depth of invasion.At the same time,the relationship between postoperative chemotherapy and the5-year survival rate among different subgroups were also analyzed.RESULTS:The overall 5-year survival rate of the entire cohort was 63.7%.The 5-year survival rate was poor in those patients who were:(1)more than 65 years old;(2)with tumor size larger than 4 cm;(3)with tumor located in the upper portion of the stomach;and(4)with pT3 tumor.The survival rate was improved significantly by extended lymphadenectomy only in patients with pT3 tumor(P=0.019),but not in other subgroups.Moreover,there was no significant difference in survival rate between patients with and without postoperative chemotherapy among all of the subgroups(P>0.05).CONCLUSION:For gastric cancer patients without lymph node metastasis,extended lymphadenectomy could improve the survival rate of those who have pT3-stage tumor.However,there was no evidence of a survival benefit from postoperative chemotherapy alone.

Clinical control effect analysis of intravenous infusion of lidocaine and dexmedetomidine for prevention and treatment of CRBD

Objective To investigate the clinical value of intravenous lidocaine in reducing CRBD in male patients who need catheterization after general anesthesia.Methods A total of 210 male patients who underwent elective general anesthesia in our hospital from May 2017 to April 2018 were selected.Random number table method was used to divide into the lidocaine group(1.5 mg?kg-1 of intravenous lidocaine infusion during anesthesia induction,and continuous intravenous infusion of lidocaine 2 mg?kg-1?h-1 after intubation),Dexmedetomidine group(0.5μg?kg-1 of dexmedetomidine intravenously during anesthesia induction,continuous intravenous infusion of dexmedetomidine 0.4μg?kg-1?h-1 after intubation).Control group(intravenous saline infusion during anesthesia induction,continuous intravenous infusion of the same amount of saline after intubation),70 cases in each group.All three groups were placed in the bladder with a 16F comfortable urethral catheter lubricated with paraffin oil.The amount of sufentanil used during the operation,the amount of sufentanil used after surgery,and the CRBD score and VAS at different time points after extubation were compared.Scoring,HR,SBP.Results T1 to T4,the CRBD scores of the lidocaine group were lower than those of the dexmedetomidine group and the control group(P<0.05).The VAS scores of the lidocaine group were lower than those of the control group(P<0.05),the CRBD score and VAS score of the dexmedetomidine group were lower than those of the control group(P<0.05);From T0 to T4,the differences in HR and SBP between the three groups were not statistically significant(P>0.05).Conclusion Lidocaine administration in male patients requiring catheterization after general anesthesia can significantly reduce the incidence of CRBD.

Ecological Tunnel for the 21st Century: A New Conception and Methodology

This paper presents a new conception—ecological tunnel, which is contrived to meet increasingly tough challenges in the 21st century. Ecological tunnel refers to integrating ecological principles into tunnel design, construction and operation in order to create a balanced and sustainable tunnel-nature system. It consists of four elements: green tunneling, green lighting, green lining, and green recycling of excavated material. The conception, function and implementation of each part are elaborated in the paper. In addition, computer visualization technique is applied to simulate complicated internal conditions of an ecological tunnel.

Mechanistic insight into Cr(Ⅵ)retention by Si-containing ferrihydrite

Hexavalent chromium[Cr(Ⅵ)]causes serious harm to the environment due to its high toxicity,solubility,and mobility.Ferrihydrites(Fh)are the main adsorbent and trapping agent of Cr(Ⅵ)in soils and aquifers,and they usually coexist with silicate(Si),forming Si-containing ferrihydrite(Si-Fh)mixtures.However,the mechanism of Cr(Ⅵ)retention by Si-Fh mixtures is poorly understood.In this study,the behaviors and mechanisms of Cr(Ⅵ)adsorption onto Si-Fh with different Si/Fe molar ratios was investigated.Transmission electron microscope,Fourier transform infrared spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and other techniques were used to characterize Si-Fh and Cr(Ⅵ)-loading of Si-Fh.The results show that specific surface area of Si-Fh increases gradually with increasing Si/Fe ratios,but Cr(Ⅵ)adsorption on Si-Fh decreases with increasing Si/Fe ratios.This is because with an increase in Si/Fe molar ratio,the point of zero charge of Si-Fh gradually decreases and electrostatic repulsion between Si-Fh and Cr(Ⅵ)increases.However,the complexation of Cr(Ⅵ)is enhanced due to the increase in adsorbed hydroxyl(A-OH-)on Si-Fh with increasing Si/Fe molar ratio,which partly counteracts the effect of the electrostatic repulsion.Overall,the increase in the electrostatic repulsion has a greater impact on adsorption than the additional complexation with Si-Fh.Density functional theory calculation further supports this observation,showing the increases in electron variation of bonding atoms and reaction energies of inner spherical complexes with the increase in Si/Fe ratio.

A Beautiful China Initiative Towards the Harmony between Humanity and the Nature

The Beautiful China Initiative(BCI)is a vivid embodiment of the harmonious coexistence between humans and nature during modernization.Implementing the BCI is an effective method for achieving the goals of building a beautiful China,while offering a“Chinese solution”to global sustainable development.This article summarizes the progress and main experiences of the BCI,as well as analyzing the primary challenges facing its future development.Finally,five policy recommendations are proposed,which emphasize the importance of top-level design,coordinated planning,and a robust support system in the implementation of the BCI.

Wafer-level substrate-free YIG single crystal film for a broadband tunable terahertz isolator

Yttrium iron garnet(YIG)is a promising material for various terahertz applications due to its special optical properties.At present,a high-quality YIG wafer is the desire of terahertz communities and it is still challenging to prepare substrate-free YIG single crystal films.In this work,we prepared wafer-level substrate-free La:YIG single crystal films,for the first time,to our knowledge.Terahertz optical and magneto-optical properties of La:YIG films were characterized by terahertz time domain spectroscopy(THz-TDS).Results show that the as-prepared La:YIG film has an insertion loss of less than 3 dB and a low absorption coefficient of less than10 cm-1below 1.6 THz.Benefitting from the thickness of the substrate-free YIG films and low insertion loss,their terahertz properties could be further manipulated by simply using a wafer-stacking technique.When four La:YIG films were stacked,there was an insertion loss of less than 10 dB in the range of 0.1-1.2 THz.The Faraday rotation angle of the four-layer-stacked La:YIG films reached 19°,and the isolation could reach17 dB.By further increasing the stacking number to eight pieces,a remarkable Faraday rotation angle of45°was achieved with an isolation of 23 dB,which is important for practical application in the THz band.This material may provide a milestone opportunity to make various non-reciprocal devices,such as isolators and phase shifters.

Occurrence and Reduction of Hepatitis B Vaccine Hesitancy Among Medical University Students—Shanxi Province,China,2020

Summary What is already known about this topic?Previous research has primarily examined the issue of hepatitis B vaccine hesitancy in migrant workers and other adult populations.However,there is a lack of studies that have specifically investigated the prevalence of hepatitis B vaccine hesitancy among university students.What is added by this report?

Geo-environmental and mechanical behaviors of As(V)and Cd (Ⅱ)co-contaminated soils stabilized by goethite nanoparticles modified biochar

Goethite nanoparticles modified biochar(FBC)could address the weak effectiveness of conventional biochar commonly to process heavy metal(loids)(HMs)co-contamination with different charges.However,few studies have focused on the change of soil mechanical properties after stabilization.In this study,FBC was synthesized to stabilize simultaneously arsenic(As(V))(anions)and cadmium(Cd (Ⅱ))(cations)in co-contaminated soils.Batch adsorption,leaching toxicity,geotechnical properties and micro-spectroscopic tests were comprehensively adopted to investigate the stabilization mechanism.The results showed that FBC could immobilize As(V)mainly through redox and surface precipitation while stabilizing Cd (Ⅱ)by electrostatic attraction and complexation,causing soil agglomeration and ultimately making rougher surface and stronger sliding friction of contaminated soils.The maximum adsorption capacity of FBC for As(V)and Cd (Ⅱ)was 31.96 mg g^(−1) and 129.31 mg g^(−1),respectively.Besides,the dosages of FBC required in contaminated soils generally were approximately 57%higher than those in contaminated water.FBC promoted the formation of small macroaggregates(0.25-2 mm)and the shear strengths of co-contaminated soils by 21.40%and 8.34%,respectively.Furthermore,the soil reutilization level was significantly improved from 0.14-0.46 to 0.76-0.83 after FBC stabilization according to TOPSIS method(i.e.,technique for order preference by similarity to an ideal solution).These findings confirm the potential of FBC in immobilizing As(V)and Cd (Ⅱ)of co-contaminated soils and provide a useful reference for green stabilization and remediation of HMs co-contaminated sites.

Coexistence of High Fibrinogen and Low High-density Lipoprotein Cholesterol Levels Predicts Recurrent Cerebral Venous Thrombosis

Background： Cerebral venous thrombosis （CVT） may lead to serious neurological disorders; however, little is known about the risk factors for recurrent CVT. Our aim was to determine the association between elevated fibrinogen and decreased high-density lipoprotein cholesterol （HDL-C） levels with recurrent CVT. Methods： This retrospective cohort study included participants if they had a first episode of objectively defined CVT and were admitted to Xuan Wu Hospital, Capital Medical University from August 2005 to September 2009. Demographic and clinical variables were collected, as well as laboratory parameters, inchiding plasma fibrinogen and HDL-C. Patients with CVT were tbllowed for recurrent symptomatic CVT. Follow-up was through the end of September 2010. Potential predictors of recurrence were analyzed using Cox survival analysis. Results： At tile end of the lbllow-up, 95 patients were eligible lbr the study. Twelve of 95 patients （12.6%） had recurred CVT. Tile median time of recurrence was 7 months （range： 1-39 months）. Eight of these 12 （66.7%） experienced rectirrence within the first 12 months alter their initial CVT. The recurrence rate of CVT was 2.76 per 100 patient-years. Multivariate Cox regression analysis demonstrated that the coexistence of high fibrinogen （〉4.00 g/L） and low HDL-C （〈1.08 mmol/L） levels at baseline was the only independent predictor for recurrent CVT （hazard ratio： 4.69; 95% confidence interval： 1.10-20,11; P 〈 0.05）. Of tile twelve patients with recurrent CVT in our study, 7 （58.3%） had high fibrinogen plus low HDL-C levels. All 7 of these patients took warfarin for 3-12 months, and 6 of 7 had rectirrent CVT after the discontinuation of anticoagulant treatment. Conclusions： Concomitant high fibrinogen and low HDL-C levels may be associated with recurrence of CVT. The ett＇ect of potential risk lhctors related to atherothrombosis on rectinent CVT should be closely monitored.

Recent advances in electrochemical sensors for antibiotics and their applications

The abuse of antibiotics will cause an increase of drug-resistant strains and environmental pollution,which in turn will affect human health.Therefore,it is important to develop effective detection techniques to determine the level of antibiotics contamination in various fields.Compared with traditional detection methods,electrochemical sensors have received extensive attention due to their advantages such as high sensitivity,low detection limit,and good selectivity.In this mini review,we summarized the latest developments and new trends in electrochemical sensors for antibiotics.Here,modification methods and materials of electrode are discussed.We also pay more attention to the practical applications of antibiotics electrochemical sensors in different fields.In addition,the existing problems and the future challenges ahead have been proposed.We hope that this review can provide new ideas for the development of electrochemical sensors for antibiotics in the future.