Mixed‑Dimensional Assembly Strategy to Construct Reduced Graphene Oxide/Carbon Foams Heterostructures for Microwave Absorption,Anti‑Corrosion and Thermal Insulation

Considering the serious electromagnetic wave(EMW)pollution problems and complex application condition,there is a pressing need to amalgamate multiple functionalities within a single substance.However,the effective integration of diverse functions into designed EMW absorption materials still faces the huge challenges.Herein,reduced graphene oxide/carbon foams(RGO/CFs)with two-dimensional/three-dimensional(2D/3D)van der Waals(vdWs)heterostructures were meticulously engineered and synthesized utilizing an efficient methodology involving freeze-drying,immersing absorption,secondary freeze-drying,followed by carbonization treatment.Thanks to their excellent linkage effect of amplified dielectric loss and optimized impedance matching,the designed 2D/3D RGO/CFs vdWs heterostructures demonstrated commendable EMW absorption performances,achieving a broad absorption bandwidth of 6.2 GHz and a reflection loss of-50.58 dB with the low matching thicknesses.Furthermore,the obtained 2D/3D RGO/CFs vdWs heterostructures also displayed the significant radar stealth properties,good corrosion resistance performances as well as outstanding thermal insulation capabilities,displaying the great potential in complex and variable environments.Accordingly,this work not only demonstrated a straightforward method for fabricating 2D/3D vdWs heterostructures,but also outlined a powerful mixeddimensional assembly strategy for engineering multifunctional foams for electromagnetic protection,aerospace and other complex conditions.

Treatment and Clinical Management of Chronic Thromboembolic Pulmonary Hypertension:An Update of Literature Review

Chronic thromboembolic pulmonary hypertension(CTEPH)is a chronic,progressive,debilitating,and life-threa-tening complication of pulmonary embolism(PE).Recent technological advances have permitted various treat-ment options for the treatment of CTEPH,including surgery,angioplasty,and medical treatment,depending on the location and characteristics of lesions.Pulmonary endarterectomy(PEA)is the treatment of choice for CTEPH,as it offers excellent long-term outcomes and a high probability of recovery.Moreover,various medical and interventional therapies are currently being developed for patients with inoperable CTEPH.This review mainly summarizes the current treatment approaches of CTEPH,offering more options for specialist physicians to,thus,better manage chronic thromboembolic syndromes.

无穷级数变换的一种方法

本文选取“变换核”函数,利用复变函数的留数定理给出一些形式各异的无穷级数恒等式。

Facile preparation of N-doped corncob-derived carbon nanofiber efficiently encapsulating Fe2O3 nanocrystals towards high ORR electrocatalytic activity

Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction(ORR)is extremely important for promoting the commercialized applications of such catalysts.In this work,the FeCl3-containing porphyrinato iron-based covalent porous polymer(FeCl3·FeP or-CPP)was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method.Subsequent thermal-reduction pyrolysis at 700℃-900℃with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis(Fe2O3=FeCl3·FePor-CPP derived Fe2O3;NC=N-doped graphene analog;bio-C=the corncob-derived hierarchically porous graphitic biomass carbon framework).The derivedα-Fe2O3 andγ-Fe2O3 nanocrystals(5-10 nm particle diameter)were all immobilized on the N-doped bio-C micro/nanofibers.Notably,the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800℃(Fe2O3@NC&bio-C-800),exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs.RHE,respectively.In addition,Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of-6.0 mA cm-2,remarkably stability(larger than 91%retention after 10000 s),and good methanol tolerance.The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date.The high ORR activity is attributed to the uniformly distributedα-Fe2O3 andγ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m^2 g^-1.This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst.Nevertheless,comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals,NC,and bio-C on the ORR performance.

In situ construction of Co/N/C-based heterojunction on biomass-derived hierarchical porous carbon with stable active sites using a Co-N protective strategy for high-efficiency ORR,OER and HER trifunctional electrocatalysts

The facile designs and fabrication of noble metal-free electrocatalysts are highly required to achieve multifunctional catalytic activity with excellent stability in Zn-air batteries,fuel cells and water splitting systems.Herein,a heterostructure engineering is applied to construct the high performance Co,Ncontaining carbon-based multifunctional electrocatalysts with the feature of isotype(i.e.n-n type Co_(2)N_(0.67)-BHPC)and anisotype(i.e.p-n type Co_(2)O_(3)-BHPC)heterojunctions for ORR,OER and HER.The nn type Co_(2)N_(0.67)-BHPC,in which biomass(e.g.mushroom)-derived hierarchical porous carbon(BHPC)incorporated with nonstoichiometric active species Co_(2)N_(0.67),is fabricated by using an in situ protective strategy of macrocyclic central Co-N_(4) from CoTPP(5,10,15,20-tetrakis(phenyl)porphyrinato cobalt)precursor through the intermolecularπ-πinteractions between CoTPP and its metal-free analogue H_(2) TPP.Meanwhile,an unprotected strategy of macrocyclic central Co-N_(4) from CoTPP can afford the anisotype Co_(2)O_(3)-BHPC p-n heterojunction.The as-prepared n-n type Co_(2)N_(0.67)-BHPC heterojunction exhibited a higher density of Co-based active sites with outstanding stability and more efficient charge transfer at the isotype heterojunction interface in comparison with p-n type Co_(2)O_(3)-BHPC heterojunction.Consequently,for ORR,Co_(2)N_(0.67)-BHPC exhibits the more positive onset and half-wave potentials of 0.93 and 0.86 V vs.RHE,respectively,superior to those of the commercial 20 wt%Pt/C and most of Cobased catalysts reported so far.To drive a current density of 10 mA cm^(-2),Co_(2)N_(0.67)-BHPC also shows the lower overpotentials of 0.34 and 0.21 V vs.RHE for OER and HER,respectively.Furthermore,the Zn-air battery equipped with Co_(2)N_(0.67)-BHPC displays higher maximum power density(109 mW cm^(-2))and charge-discharge cycle stability.Interestingly,the anisotype heterojunction Co_(2)O_(3)-BHPC as trifunctional electrocatalyst reveals evidently photoelectrochemical enhancement compared with the photostable Co_(2)N_(0.67)-BHPC.That is to say,isotype heterojunction material(n-n type Co^(2)N_(0.67)-BHPC)is equipped with better electrocatalytic performance than anisotype one(p-n type Co_(2)O_(3)-BHPC),but the opposite is true in photoelectrochemical catalysis.Meanwhile,the possible mechanism is proposed based on the energy band structures of the Co_(2)N_(0.67)-BHPC and Co_(2)O_(3)-BHPC and the cocatalyst effects.The present work provides much more possibilities to tune the electrocatalytic and photoelectrochemical properties of catalysts through a facile combination of heterostructure engineering protocol and macrocyclic central metal protective strategy.

In-situ growth of ZnS/FeS heterojunctions on biomass-derived porous carbon for efficient oxygen reduction reaction

It is an urgent task to develop highly efficient non-noble metal electrocatalysts in the direction of ORR,but still a huge and long-term challenge.Herein,an efficient one-step pyrolysis of Sichuan pepper powder,2,2-bipyridine,FeCl3,Na SCN,and ZnCl2 at 900℃ provides the FeS/ZnS@N,S-C-900 hybrid catalyst.Transmission electron microscopy(TEM)images and Mott-Schottky curves clearly reveal the in-situ constructed abundant FeS/ZnS-based p-n junctions dispersed on the biomass-derived porous carbon surface of FeS/ZnS@N,S-C-900.The as-prepared FeS/ZnS@N,S-C-900 hybrid exhibits superior ORR performance in comparison with Pt/C in 0.1 M KOH with high onset(Eonset)and half-wave potentials(E1/2)of 1.00 and 0.880 V vs.RHE,large limiting current density(JL)of 5.60 mA cm-2,and robust durability and methanol tolerance.Impressively,upon the light irradiation,FeS/ZnS@N,S-C-900 produces a photocurrent as high as ca.0.3μA cm-2,resulting in further improvement over Eonset,E1/2,and JLof FeS/ZnS@N,S-C-900 to1.10 V vs.RHE,0.885 V vs.RHE,and 6.02 mA cm-2.Experiment in combination with theoretical calculations demonstrate the significant effect of FeS/ZnS heterojunction on the enhanced ORR catalytic activity of FeS/ZnS@N,S-C-900.This work is useful for the development of advanced heterojunction-based ORR catalysts for various energy conversion devices.

Evaluation of Cold Dew Wind Monitoring Precision for Late Rice Based on CLDAS Data in Guangxi

The low temperature process of cold dew wind( from September 19 to 27 in 2011) for late rice production was dynamically monitored by using CLDAS temperature,combined with the background information of rice cultivation from multi-source satellite database together with an reference to the monitoring indexes of cold dew wind disaster to verify the precision of CLDAS data,so as to provide a reference for monitoring chilling damage caused by cold dew wind in late rice production in Guangxi. The results showed that the cold wind dew caused heavy damage to an area of 3 159. 76 km^2,moderate damage to an area of 559. 77 km^2 and light damage to an area of 2 452. 14 km^2. The correlation coefficients between CLDAS inversion temperature and actual temperature of 12 verification meteorological stations were all larger than 0. 93,and the difference in daily average temperature was 0. 3 ℃. The time difference between maximum and minimum temperature provided by CLDAS and corresponding actual temperature from 12 meteorological stations was less than 1 h. The temperature data provided by CLDAS was in accordance with actual temperature data. With an advantage of rapidly,minutely and accurately monitoring the grade distribution of local cold dew wind disaster for late rice,CLDAS can be used in monitoring cold dew wind in late rice production in Guangxi.

Identifying Outliers in Astronomical Images with Unsupervised Machine Learning

Astronomical outliers,such as unusual,rare or unknown types of astronomical objects or phenomena,constantly lead to the discovery of genuinely unforeseen knowledge in astronomy.More unpredictable outliers will be uncovered in principle with the increment of the coverage and quality of upcoming survey data.However,it is a severe challenge to mine rare and unexpected targets from enormous data with human inspection due to a significant workload.Supervised learning is also unsuitable for this purpose because designing proper training sets for unanticipated signals is unworkable.Motivated by these challenges,we adopt unsupervised machine learning approaches to identify outliers in the data of galaxy images to explore the paths for detecting astronomical outliers.For comparison,we construct three methods,which are built upon the k-nearest neighbors(KNN),Convolutional Auto-Encoder(CAE)+KNN,and CAE+KNN+Attention Mechanism(att CAE_KNN)separately.Testing sets are created based on the Galaxy Zoo image data published online to evaluate the performance of the above methods.Results show that att CAE_KNN achieves the best recall(78%),which is 53%higher than the classical KNN method and 22%higher than CAE+KNN.The efficiency of att CAE_KNN(10 minutes)is also superior to KNN(4 h)and equal to CAE+KNN(10 minutes)for accomplishing the same task.Thus,we believe that it is feasible to detect astronomical outliers in the data of galaxy images in an unsupervised manner.Next,we will apply att CAE_KNN to available survey data sets to assess its applicability and reliability.

Functional characterization of the Arabidopsis SERRATE under salt stress

SERRATE(SE)plays critical roles in RNA metabolism and plant growth regulation.However,its function in stresseresponse processes remains largely unknown.Here,we examined the regulatory role of SE using the se-1 mutant and its complementation line under saline conditions.The expression of SE was repressed by salt treatment at both mRNA and protein levels.After treatment with different NaCl concentrations,the se-1 mutants showed increased sensitivity to salinity.This heightened sensitivity was evidenced by decreased germination,reduced root growth,more serious chlorosis,and increased conductivity of the mutants compared with the wild type.Further analysis revealed that SE regulates the pre-mRNA splicing of several well-characterized marker genes associated with salt stress tolerance.Our data thus imply that SE may function as a key component in plant response to salt stress by modulating the splicing of salt stress-associated genes.

AtWRKY75 positively regulates age-triggered leaf senescence through gibberellin pathway

WRKY transcription factors play essential roles during leaf senescence.However,the mechanisms by which they regulate this process remains largely unknown.Here,we identified the transcription factor WRKY75 as a positive regulator during leaf senescence.Mutations of WRKY75 caused a delay in agetriggered leaf senescence,whereas overexpression of WRKY75 markedly accelerated this process.Expression of senescence-associated genes(SAGs)was suppressed in WRKY75 mutants but increased in WRKY75-overexpressing plants.Further analysis demonstrated that WRKY75 directly associates with the promoters of SAG12 and SAG29,to activate their expression.Conversely,GAI and RGL1,two DELLA proteins,can suppress the WRKY75-mediated activation,thereby attenuating SAG expression during leaf senescence.Genetic analyses showed that GAI gain-of-function or RGL1 overexpression can partially rescue the accelerated senescence phenotype caused by WRKY75 overexpression.Furthermore,WRKY75 can positively regulate WRKY45 expression during leaf senescence.Our data thus imply that WRKY75 may positively modulate age-triggered leaf senescence through the gibberellin-mediated signaling pathway。

Comparative Test on New Small Watermelon Varieties with Red Flesh under Soilless Culture Conditions

In order to screen out the small watermelon varieties with red flesh suitable for soilless cultivation and to meet people's requirements of high-quality watermelons,comparative tests were conducted on 6 small watermelon varieties with red flesh under soilless culture conditions in 2018.Based on the data of field traits,yield traits,quality traits and commercial traits,the integrated results showed that ‘Chuanqi 2’ had good quality and high yield,and the overall performance was the best.

Stitching Perovskite Grains with Perhydropoly(Silazane)Anti-Template-Agent for High-Efficiency and Stable Solar Cells Fabricated in Ambient Air

All inorganic CsPbI_(3)perovskite solar cells(PSCs)have emerged as disruptive photovoltaic technology owing to their admirable photoelectric properties and the non-volatile active layer.However,the phase instability against moisture severely limits the fabrication environment for the high-efficiency devices,breaking through the confinement region to achieve scalable manufacturing has been the primary issue for future commercialization.Here,we develop a curing-anti-solvent strategy for fabricating high-quality and stable black-phase CsPbI_(3)perovskite films in ambient air by introducing an inorganic polymer perhydropolysilazane(PHPS)into methyl acetate to form anti-template agent.The cross-linked PHPS reduces moisture erosions while the hydrolyzate silanol network(–Si(OH)_(4)^(–))controls the perovskite crystal growth by forming Lewis adducts with PbI_(2)during the fabrication.The polycondensation adduct of Si–O–Si/Si–O–Pb strongly binds to CsPbI_(3)grains as a shield layer to hamper phase transition.Using the inorganic CsPbI_(3)perovskite thin-film with PHPS-modified anti-solvent processing as the light absorber,the n–i–p planar solar cell achieved an efficiency of 19.17%under standard illumination test conditions.More importantly,the devices showed excellent moisture stability,retaining about 90%of the initial efficiency after 1000 h under 30%RH.

Classifying Galaxy Morphologies with Few-shot Learning

The taxonomy of galaxy morphology is critical in astrophysics as the morphological properties are powerful tracers of galaxy evolution.With the upcoming Large-scale Imaging Surveys,billions of galaxy images challenge astronomers to accomplish the classification task by applying traditional methods or human inspection.Consequently,machine learning,in particular supervised deep learning,has been widely employed to classify galaxy morphologies recently due to its exceptional automation,efficiency,and accuracy.However,supervised deep learning requires extensive training sets,which causes considerable workloads;also,the results are strongly dependent on the characteristics of training sets,which leads to biased outcomes potentially.In this study,we attempt Few-shot Learning to bypass the two issues.Our research adopts the data set from the Galaxy Zoo Challenge Project on Kaggle,and we divide it into five categories according to the corresponding truth table.By classifying the above data set utilizing few-shot learning based on Siamese Networks and supervised deep learning based on AlexNet,VGG_16,and ResNet_50 trained with different volumes of training sets separately,we find that few-shot learning achieves the highest accuracy in most cases,and the most significant improvement is 21%compared to AlexNet when the training sets contain 1000 images.In addition,to guarantee the accuracy is no less than 90%,few-shot learning needs~6300 images for training,while ResNet_50 requires~13,000 images.Considering the advantages stated above,foreseeably,few-shot learning is suitable for the taxonomy of galaxy morphology and even for identifying rare astrophysical objects,despite limited training sets consisting of observational data only.

Screening Test of Small Seedless Watermelon Varieties in Beijing Area

[Objectives]This study was conducted to select small seedless watermelon varieties with excellent quality and high yield suitable for planting in Beijing.[Methods]Under the conditions of facility cultivation in Beijing,a screening test was conducted on seven small seedless watermelon varieties for growth process,field traits,yield traits,fruit quality,and disease resistance.[Results]Varieties Mitong,Motong and Tianbao Xiaowuzi had a short growth period and relatively stable growth,and bore fruit easily,and their female flowers were closely spaced.Their yields exceeded 60000 kg/hm~2,ranking in the top three among all varieties.The fruit had a thin skin,a bright red flesh color,and a high mass fraction of soluble solids in the center.The flesh was tight or crispy,and tasted good.They also showed good disease resistance.Overall,they showed excellent comprehensive agronomic traits,and are thus suitable for facility cultivation in Beijing and its surrounding areas.[Conclusions]This study provides a theoretical basis for the upgrading of varieties and the increase in production and farmers'income in the suburbs of Beijing.

Comparative Test on Spring Medium-sized Watermelon Varieties in Beijing

[Objectives]This study was conducted to select suitable medium-sized watermelon varieties for early spring cultivation in Beijing.[Methods]Seven watermelon varieties were collected,including Beinong Tianjiao 2,Beinong Tianjiao,Hongfuji,Yongfeng 1,Beinong Futian,Beinong Shijia,and Beinong Jinxiu,and Jingxin 2 was used as the control check(CK).The growth period,morphological traits,yield traits and fruit quality of the tested varieties were investigated.[Results]Beinong Tianjiao 2 had an earlier maturation stage,a fruit development period of 38 d and a total growth period of 118 d.It showed stable growth,with a single fruit weight of 7.56 kg,a fruit setting rate of 0.99 per plant,and a yield of 83076.9 kg/hm~2,which ranked,respectively,second,first,and second among all tested varieties,and were significantly superior to the CK.Furthermore,this variety had thin and tough peel,a bright red flesh color,high central sugar content,loose and crisp flesh,and a good taste.[Conclusions]It is preliminarily believed that it is suitable for early spring watermelon production in Beijing area.

Effects of Different Concentrations of Paclobutrazol on Seedling Quality of Small Seedless Watermelon in Autumn

[Objectives]The paper was to explore the effects of different concentrations of paclobutrazol on seedling quality of small seedless watermelon in autumn.[Methods]The leaves of watermelon seedlings were sprayed with 30,50,80 and 120 mg/L paclobutrazol at cotyledon expansion stage,and those sprayed with tap water were used as control.[Results]All the treatments of paclobutrazol effectively inhibited the excessive growth of watermelon at seedling stage,significantly enhanced the leaf quality of watermelon seedlings and promoted root growth.The seedlings treated by 50 mg/L paclobutrazol had the best performance compared with the control:a decrease of hypocotyl by 37.9%,an increase of plant dry weight by 46.55%,significantly increased seedling strength index,deep green leaf color,thick leaves,an increase of specific leaf weight by 28.13%,and significantly heavier root weight and longer length.[Conclusions]The results will provide a reference for strong seedling cultivation of small seedless watermelon.

Screening of Red-flesh Small Watermelon Varieties for Substrate Cultivation in Spring Greenhouses

[Objectives] This study was conducted to screen small watermelon varieties suitable for spring greenhouses. [Methods] The field traits, yield traits, quality traits and commodity of 6 new red-flesh watermelon varieties were compared. [Results] "Jingmei 3 K" and "Sumeng No.5" had obvious advantages in quality traits, yield traits, and commodity traits. The yield reached 62 163.3 and 63 733.5 kg/hm2, respectively;the single melon weights reached 2.16 and 2.21 kg, respectively;and the central sugar content reached 13.2% and 13.1%, respectively. Meanwhile, the juice contents were high, and the taste was sweet and refreshing. They are suitable for planting under the condition of substrate cultivation technology. [Conclusions] This study provides a theoretical basis for large-area substrate cultivation and production.

Environmental Factors for Different Growth Stages of Small Water-melons in Spring Greenhouse in Beijing

This experiment mainly monitored the high-density planting conditions of small watermelons in spring greenhouses in Beijing by US350 environmental sensors. Besides,it analyzed the requirements for environmental factors in different growth stages of watermelons. The experiment obtained the following results.( i) Under the condition of high-density planting of small watermelons,the average air temperature range was 17. 48-21. 16℃ at the seedling hardening stage,the average air temperature range was 16. 68-25. 53℃ at the tendril elongation stage,and the average air temperature range was 15. 98-32. 06℃ at the fruiting stage. The average soil temperature range was 20. 56-23. 03℃ at the seedling hardening stage,the average soil temperature range was 20. 44-25. 51℃ at the tendril elongation stage,and the average soil temperature range was 18. 72-28. 84℃ at the fruiting stage. The average light intensity range was 2 359. 15-8 207. 44 Lux at the seedling hardening stage,the average light intensity range was 551. 98-9 170. 77 Lux at the tendril elongation stage,and the average light intensity range was 1 253. 59-9 644. 01 Lux at the fruiting stage. The average relative humidity range was 60. 69%-76. 40% at the seedling hardening stage,the average relative humidity range was 60. 85%-89. 89% at the tendril elongation stage,and the average relative humidity range was 42. 14%-93. 00% at the fruiting stage. The CO2 concentration range was 455-631 m L/m3 at the growth stage.

Exploration of Scientific Research Mentorship on the Cultivation of Undergraduate Students Innovation Ability

In order to improve the quality of undergraduate training and cultivate students innovation ability,more and more colleges and universities are implementing the research mentorship system among undergraduates.The study summarizes the main role of mentorship on the cultivation of innovation ability,analyzes the problems in the implementation of mentorship,and proposes corresponding solutions.

Main Practices and Future Development of the Green Food Cane Sugar Industry in Guangxi

The present situation of sugarcane production in Guangxi was introduced.The main practices of Guangxi green food cane sugar industry development were overviewed in terms of the green production for improving quality of sugarcane in Guangxi,green mechanism and joint development,block management for ensuring quality,green recycling and turning waste into treasure,building double-high bases for improving quality and increasing quantity,and sustainable development and thoroughly implementation by taking up residence.Prospects for the future development of the green food cane sugar industry in Guangxi were put forward.