开放式仪器分析教学实验设计——基于LEGO积木的模块化激光诱导荧光检测系统的构建

基于市售乐高(LEGO)积木和3D打印积木构建的光学模块,发展了适用于本科生仪器分析教学实验的模块化激光诱导荧光(Laserinducedfluorescence,LIF)检测系统。将该系统的构建过程引入本科生仪器分析的实验教学中,指导学生基于不同功能的积木块,实现LIF系统的组装和搭建,并应用于对荧光素钠溶液浓度的测定。该系统具有成本低、易构建、操作灵活等特点,模块化的构建形式大大降低了仪器搭建门槛,即使没有前期经验的本科生也可在3 h内搭建完成。将模块化构建思想引入开放式教学环节,可激发学生对仪器分析课程的兴趣和热情,同时有助于加深学生对荧光分析原理和LIF检测系统结构的理解,在系统构建过程中还能锻炼学生的动手能力,提高学生发现问题和和解决问题的能力。

Ecosystem Health Assessment of Honghu Lake Wetland of China Using Artificial Neural Network Approach

Honghu Lake,located in the southeast of Hubei Province,China,has suffered a severe disturbance during the past few decades.To restore the ecosystem,the Honghu Lake Wetland Protection and Restoration Demonstration Project(HLWPRDP) has been implemented since 2004.A back propagation(BP) artificial neural network(ANN) approach was applied to evaluatinig the ecosystem health of the Honghu Lake wetland.And the effectiveness of the HLWPRDP was also assessed by comparing the ecosystem health before and after the project.Particularly,12 ecosystem health indices were used as evaluation parameters to establish a set of three-layer BP ANNs.The output is one layer of ecosystem health index.After training and testing the BP ANNs,an optimal model of BP ANNs was selected to assess the ecosystem health of the Honghu Lake wetland.The result indicates that four stages can be identified based on the change of the ecosystem health from 1990 to 2008 and the ecosystem health index ranges from morbidity before the implementation of HLWPRDP(in 2002) to middle health after the implementation of the HLWPRDP(in 2005).It demonstrates that the HLWPRDP is effective and the BP ANN could be used as a tool for the assessment of ecosystem health.

Effects of ultrasound on the desulfurization performance of hot coal gas over Zn-Mn-Cu supported on semi-coke sorbent prepared by high-pressure impregnation method

Zn-Mn-Cu/SC（U） sorbent was hydrothermally synthesized by ultrasound-assisted high-pressure impregnation method with semi-coke（SC）as support and the mixed solution of zinc nitrate,manganese nitrate and copper nitrate as active component precursors.The desulfurization performances of hot coal gas on the prepared sorbent at a mid-temperature of 500°C were tested in fixed-bed reactor.Morphology and pore structure of the prepared sorbent were also characterized by TEM,N2adsorption/desorption isotherms and XRD.For comparison,the sorbent of Zn-Mn-Cu/SC prepared by conventional high-pressure impregnation was also evaluated and characterized in order to study the effects of ultrasound treatment.Zn-Mn-Cu/SC（U） sorbent prepared by high-pressure impregnation under ultrasound-assisted condition showed a better desulfurization performance than Zn-Mn-Cu/SC.It could remove H2 S from 1000×10-6m3/m3 to 0.1×10-6m3/m3 at 500°C and maintained for 12.5 h with the sulfur capacity of 7.74%,in which both the breakthrough time and sulfur capacity were about 32% and 51% higher than those of Zn-Mn-Cu/SC sorbent.The introduction of ultrasound during high-pressure impregnation process greatly improved the morphology and pore structure of the sorbent.The ultrasonic treatment made particle size of active components smaller and made them more evenly disperse on semi-coke support,which provided more opportunities to contact with H2S in coal-based gases.However,there were no any difference in compositions and existing forms of active components on the Zn-Mn-Cu/SC and Zn-Mn-Cu/SC（U） sorbents.

A numerical investigation of gas flow behavior in two-layered coal seams considering interlayer interference and heterogeneity

Multiple-seam gas coproduction is a technology with potential to achieve economic targets.Physical experiments could replicate gas flow dynamics in two seams.In this study,numerical simulation was conducted based on physical experiments.Through calibration,the simulated results agreed with the experimental results.Three findings were obtained.First,the pressure distribution intrinsically depends on the depressurization effectiveness in each coal seam.The gas pressure difference and interval distance influence the pressure distribution by inhibiting depressurization in the top seams and bottom seams,respectively.Second,the production contribution shows a logarithmic relationship with the permeability ratio.The range of the production contribution difference grows from 11.24%to 99.99%when the permeability ratio increases 50 times.By comparison,reservoir pressure has a limited influence,with a maximum of 13.64%.Third,the interlayer interference of the top seams and bottom seams can be intensified by the reservoir pressure difference and the interval distance,respectively.The proposed model has been calibrated and verified and can be directly applied to engineering,serving as a reference for reservoir combination optimization.In summary,coal seams with a permeability ratio within 10,reservoir pressure difference within 1.50 MPa,and interval distances within 50 m are recommended to coproduce together.

石墨烯/聚甲醛复合材料的摩擦学性能

以市售聚甲醛为原料,采用注塑法制备石墨烯/聚甲醛复合材料,并进行了摩擦学性能研究。差示扫描量热分析结果表明,石墨烯的加入会导致材料熔点降低;光学显微镜图片显示,石墨烯有助于细化晶粒。加入石墨烯后,复合材料的弯曲强度有所提升,冲击强度、拉伸强度出现一定程度的下降,略低于原材料,但耐磨性有显著的提升。石墨烯的加入明显降低了复合材料的摩擦系数及磨损量,且当石墨烯质量分数为0.3%时,复合材料表现出最优的减摩耐磨性,摩擦系数和磨损量分别降低了53.6%和72.5%。

ZnO nanorod decorated by Au-Ag alloy with greatly increased activity for photocatalytic ethylene oxidation

In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.

Lateral Pressure of RC Silos with Static and Dynamic Granular Materials

This paper aims at analyzing material-induced lateral pressure of RC cylinder silo in both static and dynamic condition using the finite element method( FEM). In the finite element software ABAQUS,concrete material is modeled by concrete damaged plasticity model,and stored materials in silo is modeled by the hypoplastic theory.In terms of numerical model,shell elements( S4R) and solid elements( C3D8) are applied for model silo wall and stored materials respectively. The interaction between silo wall and stored materials is simulated by Coulomb friction model and penalty contact constrain provided by ABAQUS.The numerical results are verified with the existing experimental data that are designed to ensure the validation of such numerical model using FEM and it obtains good agreements between numerical results and experimental data. Then the material parameters are analyzed in both static and dynamic condition.According to the analysis,it is clear that critical friction angle,initial void ratio and minimum void ratio have an obvious effect on static lateral pressure while all the material parameters affect dynamic lateral pressure at different levels. In addition,differences of silo wall between elastic and plastic state are analyzed in dynamic condition. The numerical results show that it contributes to increasing dynamic pressure when silo wall enters into the plastic state. Finally,this paper discusses the time-history lateral pressure at different heights along silo wall,and analytical results indicate that larger acceleration values play main roles in producing the maximum lateral pressure at higher part of the silo wall.

The expression of Bcl-2 and Bax produced by sub-chronic intoxication with the cyanotoxin Microcystin-LR

Objective:We explored the role and molecular mechanism of Microcystin-LR(MC-LR) in hepatocarcinogenesis.Methods:The two-stage-medium-term theory was applied to the establishment of the animal model.The promoting effect of MC-LR on liver tumor was evaluated with the Albert γ-GT methods.During the tumor-promoting course,the effects of MC-LR on the regulation and expression of the Bcl-2 and Bax genes were studied with immunohistochemical technique and RT-PCR.Results:MCLR could enhance the positive reaction of Albert γ-GT(GGT),a preneoplasm marker.The positive reaction rate of GGT in diethylnitrosamine(DEN) + MC group was significantly higher than that in the DEN control group.The protein and RNA expression of Bcl-2 was significantly increased by MC-LR,and that the protein expression of Bax was decreased simultaneously.Conclusion:These results indicate that the MC-LR can inhabit apoptosis through the Bcl-2 and Bax genes.Therefore,we conclude that the expression change of Bcl-2 and Bax genes possibly plays an important role in the promotion of liver tumor by MC-LR.

Research on Representative Engineering Applications of Anemometer Towers Location in Complex TopographyWind Resource Assessment

The typical location and number of anemometer towers in the assessed area are the key to the accuracy of wind resource assessment in complex topography.As calculation examples,this paper used two typical complex topography wind farms in Guangxi,Yunnan province in China.Firstly,we simulated the wind resource status of the anemometer tower in the Meteodyn WT software.Secondly,we compared the simulated wind resource with the actual measured data by the anemometer tower in the same situation.Thirdly,we analyzed the influence of anemometer tower location and quantity in the accuracy of wind resource assessment through the comparison results.The results showed that the range which the anemometer tower can represent is limited(<5 kilometers),and the prediction error more than 5%.Besides,the anemometer towers in special terrain areas(such as wind acceleration areas)cannot be used as a representative choice.The relative error of the simulated average annual wind speed by choose different number of anemometer towers is about 4%,and the grid-connected power generation more than 6%.The representative effect of anemometer towers is of crucial for improving the accuracy of wind resource assessment in engineering applications.

Mapping and Quantifying White Mold in Soybean across South Dakota Using Landsat Images

White Mold of soybeans (Glycine Max), also known as Sclerotinia stem rot (Sclerotinia sclerotiorum), is among the most important fungal diseases that affect soybean yield and represents a recurring annual threat to soybean production in South Dakota. Accurate quantification of white mold in soybean would help understand white mold impact on production;however, this remains a challenge due to a lack of appropriate data at a county and state scales. This study used Landsat images in combination with field-based observations to detect and quantify white mold in the northeastern part of South Dakota. The Random Forest (RF) algorithm was used to classify the soybean and the occurrence of white mold from Landsat images. Results show an estimate of 132 km2, 88 km2, and 190 km2 of white mold extent, representing 31%, 22% and 29% of the total soybean area for Marshall, Codington and Day counties, respectively, in 2017. Compared with ground observations, it was found that soybean and white mold in soybean fields were respectively classified with an overall accuracy of 95% and 99%. These results highlight the utility of freely available remotely sensed satellite images such as Landsat 8 images in estimating diseased crop extents, and suggest that further exploration of consistent high spatial resolution images such as Sentinel, and Rapid-Eye during the growing season will provide more details in the quantification of the diseased soybean.

Chemical constituents,pharmacological activities and quality evaluation methods of genus Hippocampus:A comprehensive review

The genus Hippocampus is a multi-origin animal species with high medicinal and healthcare values.About 57 species of Hippocampus spread worldwide,of which about 14 species can be used as medicine,showing anti-oxidation,anti-inflammation,anti-depressant,anti-hypertension,anti-prostatic hyperplasia,antivirus,anti-apoptotic,antifatigue,and so on.And those pharmacological effects are mainly related to their active ingredients,including amino acids,abundant proteins(peptides and oligopeptides),fatty acids,nucleosides,steroids,and other small molecular compounds.The main means of authentication of Hippocampus species are morphological identification,microscopic identification,thin layer chromatography method,fingerprint method and genomics method.This review will provide useful insight for exploration,further study and precise medication of Hippocampus in the future.

Identification of soybean in Argentina using Sentinel-2 composite images

Soybean is one of the most important oil crops, and Argentina is the third-largest soybean producer in the world, accounting for 17% of the global soybean yield. Timely and accurate information on soybean spatial distribution is critical for ensuring global food security. Sentinel-2 multispectral data and machine learning classification models are used to investigate the potential of soybean identification in the early stage of the growing season in Argentina, with the help of Google Earth Engine (GEE). The earliest time window and optimal feature set for soybean identification are explored. Results are as follows: 1) the random forest (RF) classification model demonstrated the highest level of classification accuracy compared to the backpropagation neural network (BPNN), support vector machine (SVM), and naive Bayes (NB) models;2) Soybean can be accurately identified as early as the end of February (filling stage), which is approximately one month before harvest;3) The optimal feature-subset can reduce the amount of input data by 80% while maintaining high classification accuracy. The overall accuracy (OA) of the RF classification model is 85.87%, and the relative error between the estimated soybean planting area and the agricultural statistics is 3.45%. This study provided a high-precision method for early-season identification of soybeans over large scales. The results can provide a data support for early futures trading and agricultural insurance, as well as a reference for policy-making to ensure global soybean food security.

Impact of H_(2)S on Hg^(0)capture performance over nitrogen-doped carbon microsphere sorbent:experimental and theoretical insights

A nitrogen-doped carbon microsphere sorbent with a hierarchical porous structure was synthesized via aggregation-hydrothermal carbonization.The Hg^(0)adsorption performance of the nitrogen-doped carbon microsphere sorbent was tested and compared with that of the coconut shell activated carbon prepared in the laboratory.The effect of H_(2)S on Hg^(0)adsorption was also investigated.The nitrogen-doped carbon microsphere sorbent exhibited superior mercury removal performance compared with that of coconut shell activated carbon.In the absence of H_(2)S at a low temperature(≤100℃),the Hg^(0)removal efficiency of the nitrogen-doped carbon microsphere sorbent exceeded 90%.This value is significantly higher than that of coconut shell activated carbon,which is approximately 45%.H_(2)S significantly enhanced the Hg^(0)removal performance of the nitrogen-doped carbon microsphere sorbent at higher temperatures(100–180℃).The hierarchical porous structure facilitated the diffusion and adsorption of H_(2)S and Hg^(0),while the nitrogen-containing active sites significantly improved the adsorption and dissociation capabilities of H_(2)S,contributing to the generation of more active sulfur species on the surface of the nitrogen-doped carbon microsphere sorbent.The formation of active sulfur species and HgS on the sorbent surface was further confirmed using X-ray photoelectron spectroscopy and Hg^(0)temperature-programmed desorption tests.Density functional theory was employed to elucidate the adsorption and transformation of Hg^(0)on the sorbent surface.H_(2)S adsorbed and dissociated on the sorbent surface,generating active sulfur species that reacted with gaseous Hg^(0)to form HgS.

Toward a research framework to conceptualize data as a factor of production:The data marketplace perspective

The widespread use of machine learning techniques and artificial intelligence algorithms has highlighted the strategic role of data.To acquire data for training algorithms and eventually empowering the digital transformation,data marketplaces are often required to support and coordinate cross-organizational data transactions.However,the prior industry practices have suggested that the transaction costs in the data marketplaces are severely high,and the supporting infrastructure is far from mature.This paper proposes a data attributes-affected data exchange(DADE)conceptual model to understand the challenges and directions for developing data marketplaces.Specifically,our model framework is built upon two dimensions,data lifecycle maturity and data asset specificity.Based on the DADE model,we propose four approaches for developing data marketplaces and discuss future research directions with an overview of computational methods as potential technical solutions.

Correlation between the mechanical properties and the<110>texture in a hot-rolled nearβtitanium alloy

1.Introduction Nearβtitanium alloys have been considered as a potential material to fabricate high-strength fasteners in aerospace field owing to their high specific strength,good crack and fatigue resistance[1,2].It is well known that the processing technology determines the microstructure,and the microstructure eventually correlates with the performance of alloys.

Spatiotemporal characteristics of white mold and impacts on yield in soybean fields in South Dakota

White mold of soybeans is one of the most important fungal diseases that affect soybean production in South Dakota.However,there is a lack of information on the spatial characteristics of the disease and relationship with soybean yield.This relationship can be explored with the Normalized Difference Vegetation Index(NDVI)derived from Landsat 8 and a fusion of Landsat 8 and the Moderate Resolution Imaging Spectroradiometer(MODIS)images.This study investigated the patterns of yield in two soybean fields infected with white mold between 2016 and 2017,and estimated yield loss caused by white mold.Results show evidence of clustering in the spatial distribution of yield(Moran's I=0.38;p<0.05 in 2016 and Moran's I=0.45;p<0.05 in 2017)that can be explained by the spatial distribution of white mold in the observed fields.Yield loss caused by white mold was estimated at 36%in 2016 and 56%in 2017 for the worse disease pixels,with the most accurate period for estimating this loss on 21 August and 8 September for 2016 field and 2017 field,respectively.This study shows the potential of free remotely sensed satellite data in estimating yield loss caused by white mold.

Mapping Crop Phenology in Near Real-Time Using Satellite Remote Sensing: Challenges and Opportunities

Crop phenology is critical for agricultural management,crop yield estimation,and agroecosystem assessment.Traditionally,crop growth stages are observed from the ground,which is time-consuming and lacks spatial variability.Remote sensing Vegetation Index(VI)time series has been used to map land surface phenology(LSP)and relate to crop growth stages mostly after the growing season.In recent years,high temporal and spatial resolution remote sensing data have allowed near-real-time mapping of crop phenology within the growing season.This paper summarizes two classes of near-real-time mapping methods,i.e.,curve-based and trend-based approaches.The curve-based approaches combine the time series VIs and crop growth stages from historical years with the current observations to estimate crop growth stages.The curve-based approaches are capable of a shortterm prediction.The trend-based approaches detect upward or downward trends from time series and confirm the trends using the increasing or decreasing momentum and VI thresholds.The trend-based approaches only use current observations.Both curve-based and trend-based approaches are promising in mapping crop growth stages timely.Nevertheless,mapping crop phenology near real-time is challenging since remote sensing observations are not always sensitive to crop growth stages.The accuracy of crop phenology detection depends on the frequency and availability of cloud-free observations within the growing season.Recent satellite datasets such as the harmonized Landsat and Sentinel-2(HLS)are promising for mapping crop phenology within the season over large areas.Operational applications in the near future are feasible.

LncRNA-AP006284.1 promotes prostate cancer cell growth and motility by forming RNA-DNA triplexes and recruiting GNL3/SFPQ complex to facilitate RASSF7 transcription

Long noncoding RNAs(lncRNAs)are known to be involved in transcriptional regulation and their deregulation is associated with the development of human diseases such as cancer.1,2 LncRNA can directly bind to purine-rich double-stranded DNA sequences through Hoogsteen base pairing to form an RNA-DNA triplex motifs and regulate gene expression.3,4,5 However,its regulatory mechanisms and functions in tumors remain unclear.Here,we report that the LMNTD2 antisense RNA 1(LMNTD2-AS1,also known as AP006284.1)is highly expressed in prostate cancer(PCa)and positively correlated with the expression of its adjacent coding gene N-terminal Ras-association domain family 7(RASSF7).Mechanistically,AP006284.1 tethers to the RASSF7 promoter via RNA-DNA triplexes in cis-acting manner,which enhances chromatin accessibility and recruits the transcription factor complex GNL3/SFPQ to activate the expression of RASSF7,a repressor of the Hippo signaling pathway.Consistently,overexpression of either AP006284.1 or RASSF7 inactivated the Hippo signaling and malignant proliferation of PCa cells.

Morphology characteristics of α precipitates related to the crystal defects and the strain accommodation of variant selection in a metastableβtitanium alloy

Profound and comprehensive investigations on the morphology characteristics ofαprecipitates are essential for the microstructural control of metastableβtitanium alloys.At the very beginning of aging treatment,intragranularαprecipitates with a dot-like morphology begin to generate nearby the dislocations,then those dot-likeαprecipitates with the same crystallographic orientation tend to connect with each other to develop a lath-like morphology.With the progress of aging treatment,the orientated lath-likeαprecipitates gradually combine with each other to form the V-shaped clusters or the triangular ones.The dislocations of{110}_(β)<111>βedge type are evidenced within theβgrains,and it is found that variant selection ofαprecipitates induced by the transformation strain and the interplay betweenαvariants and the dislocations are confirmed as the key factors for the formation of the V-shaped or triangular clusters.The results of this work could provide underlying knowledge on the morphology characteristics of intraguranularαprecipitates related to the crystal defects and the strain accommodation ofαvariants in metastableβtitanium alloys.