Defective TiO_(2)-graphene heterostructures enabling in-situ electrocatalyst evolution for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as one of the promising next-generation energy storage systems because of their high energy density. While the low utilization of sulfur and sluggish reaction kinetics would lead to degradation of electrochemical performance and thus hinder the practical application of Li-S batteries. Herein, a double-shelled TiO_(2)-graphene heterostructure (H-TiO_(2)/rGO) with abundant oxygen vacancies (OVs) and highly exposed active plane as advanced host material in Li-S batteries is designed. This rational structure not only provides sufficient active sites and lower bandgap for lithium polysulfides (LiPSs), but also builds smooth adsorption-diffusion-conversion of LiPSs on catalyst, which greatly reduces interfacial energy barrier and promotes the utilization of sulfur through suppressing the devastating shuttling effect. Combining the synergetic merits of strong anchoring ability and catalyzing the of LiPSs, the electrode (S-TiO_(2)/rGO-1) exhibits superior rate performance and long lifespan (1000 cycles at 1C, 0.023% capacity loss per cycle) with high columbic efficiency. This work paves an alternative way to establish smooth adsorption-diffusion-conversion of polysulfides on catalyst in Li-S batteries and provides a new sight to understand catalyst design in energy storage devices.

Adsorption Capacity for Phosphorus Comparison among Activated Alumina, Silica Sand and Anthracite Coal

Experimental researches on adsorptive capacity of activated alumina, silica sand and anthracite coal for phosphorus were conducted. Results showed that performances of three filter media were all in line with Langmuir isotherm, and activated alumina adsorptive performance was much better than silica sand and an-thracite coal for phosphorus removal. The adsorptive capacity of activated alumina, silica sand and anthracite coal for phosphorus was 3333μg/g, 49μg/g and 100μg/g respectively. Activated alumina displayed adsorp-tive function well for phosphorus, because its inner porosity, specific surface area and surface isoelectric pH value were all higher than those of other two filter media. While activated alumina was used as filter material in water treatment process, phosphorus would be removed strongly because of adsorptive characteristic of activated alumina.

Novel DDoS Feature Representation Model Combining Deep Belief Network and Canonical Correlation Analysis

Distributed denial of service(DDoS)attacks launch more and more frequently and are more destructive.Feature representation as an important part of DDoS defense technology directly affects the efficiency of defense.Most DDoS feature extraction methods cannot fully utilize the information of the original data,resulting in the extracted features losing useful features.In this paper,a DDoS feature representation method based on deep belief network(DBN)is proposed.We quantify the original data by the size of the network flows,the distribution of IP addresses and ports,and the diversity of packet sizes of different protocols and train the DBN in an unsupervised manner by these quantified values.Two feedforward neural networks(FFNN)are initialized by the trained deep belief network,and one of the feedforward neural networks continues to be trained in a supervised manner.The canonical correlation analysis(CCA)method is used to fuse the features extracted by two feedforward neural networks per layer.Experiments show that compared with other methods,the proposed method can extract better features.

A Novel DDoS Attack Detection Method Using Optimized Generalized Multiple Kernel Learning

Distributed Denial of Service(DDoS)attack has become one of the most destructive network attacks which can pose a mortal threat to Internet security.Existing detection methods cannot effectively detect early attacks.In this paper,we propose a detection method of DDoS attacks based on generalized multiple kernel learning(GMKL)combining with the constructed parameter R.The super-fusion feature value(SFV)and comprehensive degree of feature(CDF)are defined to describe the characteristic of attack flow and normal flow.A method for calculating R based on SFV and CDF is proposed to select the combination of kernel function and regularization paradigm.A DDoS attack detection classifier is generated by using the trained GMKL model with R parameter.The experimental results show that kernel function and regularization parameter selection method based on R parameter reduce the randomness of parameter selection and the error of model detection,and the proposed method can effectively detect DDoS attacks in complex environments with higher detection rate and lower error rate.

Synthesis,phase transformation and applications of CeCO_(3)OH:A review

CeCO_(3)OH has a unique crystal structure and excellent optical,electronic and catalytic properties,which has been widely investigated for many applications.Interestingly,ceria obtained from CeCO_(3)OH has a morphology that is similar to that of the precursor,and the CeO_(2)-based products obtained from CeCO_(3)OH exhibit outstanding properties,such as catalytic performances,owing to their designed morphology and oxygen vacancies(OVs).To introduce CeCO_(3)OH into a wider range of potential researchers,we first systematically review the physico-chemical properties,synthesis,reaction and morphology tuning mechanism of CeCO_(3)OH,and summarize the conversion behavior from CeCO_(3)OH to ceria.Then,we thoroughly survey the applications of CeCO_(3)OH and its conversion products.Suggestions for further investigations of CeCO_(3)OH are also made in this review.It is hoped that the exhaustive co mpilation of the valuable properties and considerable potential investigations of CeCO_(3)OH will promote further applications of CeCO_(3)OH and CeO_(2)-based functional materials.

DDoS Attack Detection via Multi-Scale Convolutional Neural Network

Distributed Denial-of-Service(DDoS)has caused great damage to the network in the big data environment.Existing methods are characterized by low computational efficiency,high false alarm rate and high false alarm rate.In this paper,we propose a DDoS attack detection method based on network flow grayscale matrix feature via multi-scale convolutional neural network(CNN).According to the different characteristics of the attack flow and the normal flow in the IP protocol,the seven-tuple is defined to describe the network flow characteristics and converted into a grayscale feature by binary.Based on the network flow grayscale matrix feature(GMF),the convolution kernel of different spatial scales is used to improve the accuracy of feature segmentation,global features and local features of the network flow are extracted.A DDoS attack classifier based on multi-scale convolution neural network is constructed.Experiments show that compared with correlation methods,this method can improve the robustness of the classifier,reduce the false alarm rate and the missing alarm rate.

Thermopressure Coupling Effect Mimicking Natural Graphite Formation to Enhance the Storage K-Ion Performance of Carbonaceous Heterostructures

Borrowing from natural mechanisms for material design can lead to functional mimicry and improvement.Inspired by graphite formation,a thermopressure coupling strategy under micropressure(<400 Pa)is applied to prepare carbon anodes.A thermopressure response is discovered based on the cellulose precursor.Here,homologous graphene quantum dot/hard carbon(GQD/HC)heterostructures are synthesized.Under 181.4 Pa and 1,200°C,the product shows a capacity of 310 mAh g^(−1),while the capacity of the direct carbonization product is only 120 mAh g^(−1).Prominently,the GQD/HC heterostructure displays marked mechanical strength and flexibility.The experimental and theoretical results illustrate the ion and electron transfer,coordination environment,and electronic states in the GQD/HC heterostructure and elaborate on the origin of the enhanced performance.The thermopressure coupling under micropressure mimics graphite formation,but the heterostructure has better properties than traditional carbon materials.Additionally,micropressure injects new vitality into material research.

Cerium oxide inclusion nucleation mechanism based on classical nucleation theory and two-step nucleation

It is challenging to assess the mechanism responsible for the nucleation of inclusions in metals at high temperatures.The present work therefore systematically investigates the nucleation of cerium oxide inclusions according to classical nucleation theory and a two-step nucleation mechanism.The nucleation rates and nucleation radii of these inclusions are obtained,and the results demonstrate a considerable difference between theoretical and experimental values.On the basis of a two-step nucleation mechanism,(CeO_(2))_(n) and(Ce_(2)O_(3))_(n)(n=1-6)clusters were constructed and the thermodynamic properties of both these clusters and of cerium oxide nanoparticles were analyzed.In addition,the entropies and heat capacity changes of cerium oxides were determined using first principles calculations and are found to be consistent with literature data.The present data indicate that the cerium oxide inclusion nucleation pathway can be summarized as[Ce]+[O]→(CeO_(2))n/(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(n)→(Ce_(2)O_(3))_(2)→core(Ce_(2)O_(3)crystal)-shell((Ce_(2)O_(3))_(2) cluster)nanoparticles→(Ce_(2)O_(3))bulk.

Multifunctional core/satellite polydopamine@Nd^3＋- sensitized upconversion nanocomposite： A single 808 nm near-infrared light-triggered theranostic platform for in vivo imaging-guided photothermal therapy

Significant attenuation and overheating, caused by the absorption of the excitation band （980 nm） in water, are the major obstacles in the in vivo application of lanthanide-doped upconversion nanoparticles （UCNPs）. Therefore, appropriately- structured Nd3^＋-doped UCNPs with 808 nm excitation could be a promising alternative. Herein, we developed core-shell-shell structured Nd3^＋-sensitized UCNPs as imaging agents, and decorated them onto the surface of polydopamine （PDA） to construct a novel multifunctional core/satellite nanotheranostic （PDA@UCNPs） for in vivo imaging guidance photothermal therapy using single 808 nm laser irradiation. The core-shell-shell structured design enabled outstanding upconversion luminescence properties and strong X-ray attenuation, thereby making the nanocomposites potential candidates for excellent upconversion luminescence/computed tomography dual modal imaging. In addition, the PDA core not only provides high photothermal conversion efficiency and outstanding antitumor effect, but also endows the platform with robust biocompatibility owing to its natural features. Therefore, this multifunctional nanocomposite could be a promising theranostic in future oncotherapy, with high therapeutic effectiveness but low side effects. This study would stimulate interest in designing bio- application-compatible multifunctional nanocomposites, especially for cancer diagnosis and treatment in vivo.

Preclinical evaluation and pilot clinical study of [^(18)F]AlF-labeled FAPI-tracer for PET imaging of cancer associated fibroblasts

In recent years,fibroblast activation protein(FAP)has emerged as an attractive target for the diagnosis and radiotherapy of cancers using FAP-specific radioligands.Herein,we aimed to design a novel^(18)Flabeled FAP tracer([^(18)F]Al F-P-FAPI)for FAP imaging and evaluated its potential for clinical application.The[^(18)F]Al F-P-FAPI novel tracer was prepared in an automated manner within 42 min with a non-decay corrected radiochemical yield of 32±6%(n=8).Among A549-FAP cells,[^(18)F]Al F-P-FAPI demonstrated specific uptake,rapid internalization,and low cellular efflux.Compared to the patent tracer[^(18)F]FAPI-42,[^(18)F]Al F-P-FAPI exhibited lower levels of cellular efflux in the A549-FAP cells and higher stability in vivo.Micro-PET imaging in the A549-FAP tumor model indicated higher specific tumor uptake of[^(18)F]Al F-P-FAPI(7.0±1.0%ID/g)compared to patent tracers[^(18)F]FAPI-42(3.2±0.6%ID/g)and[68 Ga]Ga-FAPI-04(2.7±0.5%ID/g).Furthermore,in an initial diagnostic application in a patient with nasopharyngeal cancer,[^(18)F]Al F-P-FAPI and[^(18)F]FDG PET/CT showed comparable results for both primary tumors and lymph node metastases.These results suggest that[^(18)F]Al F-P-FAPI can be conveniently prepared,with promising characteristics in the preclinical evaluation.The feasibility of FAP imaging was demonstrated using PET studies.

Blind position detection for large field-of-view scattering imaging

Prio-free imaging beyond the memory efect(ME)is critical to seeing through the scattering media.However,methods proposed to exceed the ME range have suffered from the availability of prior information of imaging targets.Here,we propose a blind target position detection for large field-of-view scattering imaging.Only exploiting two captured multi-target near field speckles at diferent imaging distances,the unknown number and locations of the isolated imaging targets are blindly reconstructed via the proposed scaling vecto-based detection.Autocorrelations can be calculated for the speckle regions centered by the derived positions via low.cross talk region allocation strategy.Working with the modified phase retrieval algorithm,the complete scene of the multiple targets exceeding the ME range can be reconstructed without any prior information.The effectiveness of the proposed algorithm is verified by testing on a real scattering imaging system.

Solid ion transition route to 3D S-N-codoped hollow carbon nanosphere/graphene aerogel as a metal-free handheld nanocatalyst for organic reactions

A novel metal-free bulk nanocatalyst, S--N-codoped hollow carbon nanosphere/ graphene aerogel （SNC-GA-1000）, has been successfully fabricated using a facile and clean solid ion transition route. In this method, ZnS is used as the hard template and S source, while polydopamine acts as a reducing agent and carbon source. At a high annealing temperature, Zn metal is reduced and evaporates, leaving only free S vapor to diffuse into the carbon layer. Interestingly, the as-obtained SNC-GA-1000 exhibits much higher catalytic activity in an organic reduction reaction than unloaded bare S--N-codoped carbon nanospheres. Hydrothermal reduction of the graphene oxide sheets loaded with ZnSC@olydopamine core-shell nanospheres （ZnS@PDA） affords a three-dimensional bulk graphene aerogel. Although nanosized catalysts exhibit high catalytic activities, their subsequent separation is not always satisfactory, making post-treatment difficult. This approach achieves a trade-off between activity and separability. More importantly, due to the 3D structural nature, such bulk and handheld nanocatalysts can be easily separated and recycled.

Effects of Crystallinity and Defects of Layered Carbon Materials on Potassium Storage:A Review and Prediction

Layered carbon materials(LCMs)are composed of basic carbon layer units,such as graphite,soft carbon,hard carbon,and graphene.While they have been widely applied in the anode of potassium-ion batteries,the potassium storage mechanisms and performances of various LCMs are isolated and difficult to relate to each other.More importantly,there is a lack of a systematic understanding of the correlation between the basic microstructural unit(crystallinity and defects)and the potas-sium storage behavior.In this review,we explored the key structural factors affecting the potassium storage in LCMs,namely,the crystallinity and defects of carbon layers,and the key parameters(L_(a),L_(c),d_(002),I_(D)/I_(G))that characterize the crystallinity and defects of different carbon materials were extracted from various databases and literature sources.A structure–property database of LCMs was thus built,and the effects of these key structural parameters on the potassium storage properties,including the capacity,the rate and the working voltage plateau,were systematically analyzed.Based on the structure–prop-erty database analysis and the guidance of thermodynamics and kinetics,a relationship between various LCMs and potas-sium storage properties was established.Finally,with the help of machine learning,the key structural parameters of layered carbon anodes were used for the first time to predict the potassium storage performance so that the large amount of research data in the database could more effectively guide the scientific research and engineering application of LCMs in the future.

低温磁化焙烧对高铁铝土矿溶出及磁选性能的影响

为实现高铁铝土矿铝铁元素的高效利用,采用“低温磁化焙烧-拜耳溶出-赤泥磁选”的方式处理高铁铝土矿,考察了焙烧温度、H2浓度及通入时间对高铁铝土矿溶出及磁选性能的影响。结果表明,焙烧过程中一水硬铝石脱水转变为过渡态Al2O3,矿物发生热破裂现象,比表面积增大,氧化铝溶出活性增加,在焙烧条件为焙烧温度530℃、H2浓度20vol%、H2通入时间5 min时,氧化铝相对溶出率可达97.65%。磁化焙烧过程中,针铁矿转变为赤铁矿,再由赤铁矿转变为磁铁矿,通过溶出解除了铝铁元素之间的嵌布关系,对焙烧矿的赤泥进行磁选,其铁精矿品位达62.05wt%,铁回收率为86.36%。

Molten salt synthesis of Z-scheme CeO_(2)/C_(3)N_(4) photocatalysts with excellent properties for removal of organic pollutants:Characterization,kinetics and mechanisms

In this work,we firstly synthesized a CeO_(2)/C_(3)N_(4) photocatalyst with Z-scheme heterojunction by a facile LiC-KCI molten salt method.The synthesized catalyst has an excellent quality for removing organic pollution of dyes and antibiotics in wastewater.As an example,the CeCN-1:5 prepared with a mass ratio of Ce_(2)(CO_(3))_(3)·xH_(2)O:C_(3)H_(3)N_(6)=1:5 exhibits a methylene blue(MB)removal capacity of 100%within 90 min and tetracycline(TC)removal capacity of 94.6%.After 4 cycles,the CeCN-1:5 keeps a removal efficiency of nearly 100%in 150 min for MB and 85.7%for TC.The kinetics study reveals that the MB removal process with the CeCN-1:5 fits the modified Elovich model with strong adsorption while TC removal fits the first-order model.The large surface area(238 m^(2)/g)and negative zeta potential(-39.3 mV)of CeCN-1:5 contribute to superior adsorption capacity to MB.However,the adsorption of TC is restricted due to the positive surface/pore potential in acidic solution.CeCN-1:5has combined Z-scheme heterojunction and exhibits a low recombination rate of electrons(e^(-))/holes(h^(+))and the photo-generated active radicals of·OH/·O_(2)^(-)that promotes the photocatalytic performance.This novel CeO_(2)/C_(3)N_(4) photocatalyst with an excellent photocatalysis removal activity has an enormous potential for photocatalytic applications.

Facile synthesis of nanoceria by a molten hydroxide method and its photocatalytic properties

Ceria nanoparticles were facilely synthesized by a molten NaOH-KOH hydroxide flux method with the precursor of Ce(NO3)3·6H2O under different conditions in alumina crucibles or Teflon-lined stainless steel autoclave.The XRD patterns and TEM images show that both the crystal and particle sizes of synthesized nanoceria are around 10 nm.XPS results reveal that the nanoceria obtained in alumina crucible has a Ce3+fraction of 17.1%which is higher than that of ceria synthesized in the Teflon vessel,the FTIR spectra of nanoceria prepared in alumina crucible show a stronger intensity of O-H stretching mode.UV-DRS and PL spectra results show that the nanoceria synthesized in alumina crucible with a calculated band gap of 2.9 eV has a wider responding light wavelength and a lower photogene rated electron-hole recombination rate,due to a higher concentration of oxygen vacancies(Ce^3+%).The photocatalytic results show that the degradation ratio and rate of the Rhodamine B(RhB)solution with the nanoceria synthesized in alumina crucible are 98.39%and 0.02919 min-1,both of which are larger than those of the ceria obtained from Teflon vessel.This method proves to be a simple and scalable way to synthesize nanoceria with rich oxygen vacancies and high photocatalytic activity.

Mass production of Co3O4@CeO2 core@shell nanowires for catalytic CO oxidation

In this study, Co3O4@CeO2 core@shell nanowires were successfully prepared via thermal decomposition of Co（CO3）0.5（OH）.0.11H2O@CeO2 core@shell nanowire precursors. As a CO oxidation catalyst, Co3O4@CeO2 shows remarkably enhanced catalytic performance compared to Co3O4 nanowires and CeO2 nanoparticles （NPs）, indicating obvious synergistic effects between the two components. It also suggests that the CeO2 shell coating can effectively prevent Co3O4 nanowires from agglomerating, hence effecting a substantial improvement in the structural stability of the Co3O4 catalyst. Furthermore, the fabrication of the welbdisperse4 core@shell structure results in a maximized interface area between Co3O4 and CeO2, as well as a reduced Co3O4 size, which may be responsible for the enhanced catalytic activity of Co3O4@CeO2. Further examination revealed that CO oxidation may occur at the interface of Co3O4 and CeO2. The influence of calcination temperatures and the component ratio between Co3O4 and CeO2 were then investigated in detail to determine the catalytic performance of Co3O4@CeO2 core@shell nanowires, the best of which was obtained by calcination at 250 ℃ for 3 h with a Ce molar concentration of about 38.5%. This sample achieved 100% CO conversion at a reduced temperature of 160 ℃. More importantly, more than 2.5 g of the Co3O4@CeO2 core@shell nanowires were produced in one pot by this simple process, which may be beneficial for practical applications as automobile-exhaust gas-treatment catalysts.

Integral stormwater management master plan and design in an ecological community

Urban stormwater runoff nearly discharges directly into bodies of water through gray infrastructure in China, such as sewers, impermeable ditches, and pump stations. As urban flooding, water shortage, and other environment problems become serious, integrated water environment management is becoming increasingly complex and challenging. At more than 200 ha, the Oriental Sun City community is a large retirement community located in the eastern side of Beijing. During the beginning of its construction, the project faced a series of serious water environment crises such as eutrophication, flood risk, water shortage, and high maintenance costs. To address these issues, an integral storrnwater management master plan was developed based on the concept of low impact development （LID）. A large number of LID and green stormwater infrastructure （GSI） approaches were designed and applied in the community to replace traditional stormwater drainage systems completely. These approaches mainly included bioretention （which captured nearly 85th percentile volume of the annual runoff in the site, nearly 5.4 x 10^5 m3 annually）, swales （which functioned as a substitute for traditional stormwater pipes）, waterscapes, and stormwater wetlands. Finally, a stormwater system plan was proposed by integrating with the gray water system, landscape planning, an architectural master plan, and related consultations that supported the entire construction period. After more than 10 years of planning, designing, construction, and operation, Oriental Sun City has become one of the earliest modem large-scale LID communities in China. Moreover, the project not only addressed the crisis efficiently and effectively, but also yielded economic and ecological benefits.

Is urban development an urban river killer? A case study of Yongding Diversion Channel in Beijing, China

The high population and concrete environment alter urban areas by changing temperature, rainfall runoff, and water resource utilization activities. This study was conducted to investigate the water quality features of the Yongding Diversion Channel in Beijing, China, and its relationship with rainfall and urban development. Monthly water quality data were obtained from April to October of 2004 at monitoring sites of Sanjiadian, Gaojing, Luodaozhuang, and Yuyuangtan. The monthly water quality grades from 2007 to 2011 were also investigated and compared with those of other rivers. Dissolved oxygen and pH showed greater decreases after one or two moderate rainfall events than several light rainfall events. The potassium permanganate index （CODMn）, ammonia nitrogen （NH3-N） and total phosphorus （TP） increased more after several light rainfall events than after one or two moderate or heavy rainfall events. Pollutant concentrations （CODMn, NH3-N, TP） in downstream regions showed greater changes than those in upstream areas after heavy rainfall events. Intense human activities around the channel greatly influenced the water quality of the channel in rainy season because of runoff pollution; however, heavy rainfall had a strong dilution effect on the pollutant concentrations in rivers. Overall, urban development has obviously deteriorated the water quality of the Yongding Diversion Channel as indicated by an increase in the water quality index from 3.22 in 2008 to 4.55 in 2010. The Pearson correlation between monthly rainfall and water quality indices from 2007 to 2011 ranged from 0.1286 to 0.6968, generally becoming weaker as rainfall and rainfall runoff became more random and extreme.

Burden of Acute Viral Hepatitis--China,1990−2019

What is already known about this topic?The World Health Organization’s(WHO)Global Health Estimates(GHE)reported that acute hepatitis caused 9,213 deaths and 307,720 person years of disability-adjusted life years(DALYs)in 2016,and acute hepatitis B accounted for 85.81%of all DALYs among acute hepatitis types A,B,C,and E in China.What is added by this report?In China,the percent changes in years lived with disability(YLDs)due to acute hepatitis A,B,and E in groups aged 50–69 years and 70 years or more and in all age groups for acute hepatitis C were increased from 2000 to 2019.What are the implications for public health practices?Effective vaccines,interventions,and treatments are key approaches to achieve the WHO’s goal of reducing new hepatitis infections by 90%and deaths by 65%between 2016 and 2030.