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To study the effect of different drying methods on volatile components of jasmine tea, headspace solid phase microextraction combined with gas chromatography-mass spectrometry and electronic nose technology were used for quantitative and qualitative analysis of the volatile compounds in jasmine tea dried by four methods, including heat pump drying, hot air drying, microwave drying and vacuum-freeze drying. The results showed that, the top three response values of electronic nose sensors were W1W, W2W and W5S. Under different drying treatments, it can better reflect the differences in volatile substances in jasmine tea. The results of HS-SPME-GC-MS showed that a total of 96 volatile components (alcohol esters, aldehydes, ketones, olefins and other classes) were identified in jasmine tea by four different drying methods. Among these components, the species of olefin compounds were the most with the amount of 37. The total amounts of the volatile components in jasmine tea by freeze-drying were the most abundant with a relative content of 47.382 μg/g, followed by heat pump drying with a relative content of 44.429 μg/g. And the relative contents of olefin and alcohols were higher than other components. The JTF (jasmine tea fragrance) index of jasmine tea was the highest with a amount of 4.766 by heat pump drying. Therefore, HS-SPME-GC-MS combined with electronic nose technology could be used to distinguish the quality of jasmine tea by different drying methods, and would provide theoretical reference for the selection of drying methods in jasmine tea production.

Summarizes Weissiella spp. including the isolation and identification, biological properties, acid tolerance, bacterial inhibition, extracellular polysaccharide production, probiotic properties, histological studies, and food and pharmaceutical applications, and provides suggestions for the development and utilization of Weissiella spp.

There are many unmeasurable branches along with distribution lines. The sensitivity and speed of traditional three-stage overcurrent protection lacks when applied to these lines. Even the phasor differential protection cannot identify internal faults sensitively to maintain sufficient safety under external faults. With 5G communication is penetrating the field of power grid automation, a comprehensive protection scheme for branched distribution lines is proposed. Firstly, analyze negative sequence currents phase characteristics under internal or external faults, and negative-sequence current phase-comparison protection is proposed. Secondly, in some harsh working conditions, 5G communication's synchronization cannot be guaranteed, or even out of step. A positive sequence amplitude differential protection is introduced. Finally, the three-stage overcurrent protection is combined to form a complete set of protection coordination schemes when communication interruption or some extreme situations. A 10 kV active distribution network model is built in PSCAD/EMTDC to verify the proposed protection criteria and scheme. The simulation results demonstrate the effectiveness of the proposed protection criteria and scheme.

With Ni/CeO2 as an example, which has important applications in catalysis, 17O solid-state nuclear magnetic resonance (NMR) spectroscopy was applied to explore and analyze the concentration of surface Ni ions, according to the changes in the 17O NMR intensity of surface oxygen ions. The results indicate that the Ni concentrations in the first and second top metal ion layers in 10% NiCe-500 and 20% NiCe-300 are within the ranges of 9%~17% and 8%~15%, respectively. This approach may be extended to study the concentration of the doped paramagnetic elements in the surface for a variety of doped oxide materials.

In order to solve trace-level steroid estrogen pollution in groundwater and surface water, a SPE-GC-MS approach to determine five steroid estrogens (SEs), E1, 17α-E2, 17β-E2, EE2 and E3, by optimizing of solid phase extraction (SPE), derivatization conditions and the secondary purification process of complex samples has been developed. The results show that Oasis HLB column, ethyl acetate elution and derivatizing at 40℃ for 20 min can achieve the best results for extraction. Moreover, the Generik NAX column activated by methyl is suitable for the secondary purification of complex samples. The linear ranges of E1, 17α-E2, and 17β-E2 are 5-1000 ng/L, whereas those of EE2 and E3 are 10-1000 ng/L. The detection and quantitation limits are 2-3 ng/L and 6.5-10 ng/L, respectively. The standard solution added recoveries of water samples range from 80% to 120%. The relative standard deviations of daily peak areas in the SEs determination range from 6.8% to 10%. This method was used to determine the SEs pollution levels of waters from pond, river, groundwater and sewage treatment plant effluent and results show that this detection technique can be effectively applied to the identification and evaluation of estrogen risk in surface water and groundwater samples.

The objective of this study is to clarify relay intercropping crop growth characteristics and its effects on yield formation under nitrogen application and interspecific distance. In this study, the soybean/maize strip relay intercropping system was used as the main body, to explore the crop growth rate, dry mater accumulation, and distribution, and yield differences under different nitrogen levels (nitrogen application and no nitrogen application) and interspecific distance (the spacing of soybean 30, 45, 60, 75, and 100 cm mono-cropping), to fit the process of crop dry mater accumulation, and comprehensively analyze the crop growth law and yield benefit. The results showed that the maximum growth rate of maize was reached from male stage to milking stage, and the maximum growth rate was 30 cm (MS30) without nitrogen application, which was 34.99% higher than that of monoculture maize (MM100). The growth rate of relay intercropping was significantly lower than that of monoculture soybean (SS100) before the first flowering stage, but higher than that of SS100 after the first flowering stage, with the highest spacing of 60 cm (MS60), and 78.91% higher than that of SS100 from full flowering stage to full pod stage without nitrogen application. The logistic equation could fit well the matter accumulation process of maize and soybean, and the R2 were all above 0.95. Compared with no nitrogen application, nitrogen application delayed the accumulation peak and increased the biomass of maize. The matter accumulation of intercropping soybean was slower than monoculture at the early growth stage, but MS45 and MS60 were gradually equal to or even exceeded monoculture soybean at later growth stage. Nitrogen application increased the dry matter allocation rate to the grain, and maize yield increased by 10.05% and 40.90% in two years, respectively. With the increase of interspecific distance, soybean yield increased first and then decreased, with the highest value in MS60 and the lowest value in MS30. In the two years, soybean yield in MS60 was 23.88% and 31.77% higher than MS30 under no nitrogen application and nitrogen application, respectively. The land equivalent ratio under relay intercropping was all above 1.35, among which MS60 under nitrogen application was the largest (1.89). The suitable interspecific distance (interspecific distance 60 cm) under relay intercropping can realize the cooperative growth of maize and soybean, increase crop growth rate, promote the accumulation and distribution of matter, and improve the system yield and land equivalent ratio. [ABSTRACT FROM AUTHOR]

Reasonable field configuration can improve crop growth environment and increase system yield in intercropping systems. To further improve the field configuration technology for high yield and efficiency in the soybean-maize strip intercropping system in Southwest China, the soybean-maize strip intercropping system was used as the research object, and two factor split zone design was adopted. The effects of two bandwidths of 2.0 m (B1) and 2.4 m (B2) and four plant spacings of 9 cm (P1), 11 cm (P2), 14 cm (P3), and 18 cm (P4) on soybean biomass accumulation, allocation, grain filling, and yield were comprehensively analyzed. The results showed that the net photosynthetic rate of each plant spacing treatment under B2 bandwidth was higher than that of B1, and the two--year average increased by 14.26% compared with B1 under B2. At the same bandwidth, the net photosynthetic rate reached the maximum in B1P4 and B2P4, which increased by 13.57% and 25.21% compared with B1P1 and B2P1 at flowering stage, respectively. The biomass accumulation of soybean population increased and then decreased with the increase of plant spacing under the two bandwidths, and reached the maximum at B1P3 and B2P2, respectively, and B2 increased by 9.82%--22.08% compared with B1 at maturity stage. And the increase of bandwidth and plant spacing promoted the accumulation and transfer of soybean post-flowering matter to grain. Compared with B1, post-flowering dry matter accumulation and dry matter transfer increased by 13.82--28.01% and 13.38%--37.76% under B2 treatment, respectively, and the proportion of grain matter accumulation increased to 41.80%--44.26%. The increase of biomass accumulation improved the grain filling process, and the active grain-filling period (D) of soybean under B2 was extended by 2--3 days compared with B1. The mean grain-filling rate reached its maximum at P4 and increased by 5.80% and 6.58% compared with P1 under the two bandwidths. The yield results showed that, with the increase of bandwidth and plant spacing, the effective plants decreased, and the seeds per plan and 100-seed weight increased in the soybean-maize strip intercropping model. The soybean yield under B2 bandwidth increased by 22.32%--36.87% compared with B1, it reached the maximum in B1P3 and B2P2 under the two bandwidths, respectively, and increased by 17.83%--26.44% and 10.71%--10.76% compared with B1P1 and B2P1 for two years. In summary, the soybean plant spacing of 11 cm at the bandwidth of 2.4 m can effectively improve the post-flowering dry matter accumulation and allocation, promote grain filling, increase the number of seeds per plant and 100-seed weight, improve soybean population yield, and achieve the high yield and high efficiency in the soybean-maize intercropping system. [ABSTRACT FROM AUTHOR]

Optimal allocation of water resources can solve the problems of regional water resources shortage and unreasonable utilization, and in recent years optimization algorithms have become an important tool for obtaining the results of optimal allocation of water resources. To effectively alleviate the problems of slow convergence, local optimization and prematureness in existing optimal allocation algorithms, this paper introduces a new metaheuristic algorithm: the Cheetah Optimizer (CO), with the advantages of fast convergence, robustness, and superiority-seeking ability, which is applied to the optimal allocation of water resources. Taking Taiyuan as the study area, this paper establishes a water resource optimization model with the objectives of economic, social, and ecological benefits, and CO is used to solve the model, then compares and analyzes the results with the Genetic Algorithm (GA). The results show that the total pollutant discharge of CO is within the control target of the planning year (2030), the regional satisfaction reaches 0.98, which can meet the demand for basic and development water; compared with the current year (2020), the proportion of domestic water consumption decreases by 22.58%, and the proportion of water consumption in production increases by 10.53%, 25.81% and 12.5%, respectively. The water supply ratio of surface water and groundwater is reduced by 21.70% and 11.14%, respectively, the water supply ratio of reuse water and yellow diversion water is increased by 5.43% and 27.40%. It accords with the idea of water resources allocation in Taiyuan, and verifies the effectiveness of CO. Compared with GA, CO has increased regional satisfaction, integrated water value and water distribution equity by 7.10%, 3.57% and 56.52%, respectively, reduced pollutant emissions and water shortage by 3.11% and 3.85%, at the same time, it has better coordination, which verifies the superiority of the CO. The results show that CO is reasonable and feasible to solve the optimal allocation model of water resources, which can provide a new method for solving the optimal allocation model of water resources. [ABSTRACT FROM AUTHOR]

The selection of shade-tolerant and high-light-efficient soybean varieties is one of the important research elements of the maize-soybean ribbon complex cropping model. By analyzing the differences in leaf morphology and photosynthetic physiological responses between wild and cultivated soybean seedlings under normal and shaded conditions, we can reveal their shade-tolerance mechanisms and response differences, which can provide a theoretical basis for the breeding of new shade-tolerant and high-light-efficient soybean varieties. In this study, two types of cultivated soybean (Nandou 12 and Tianlong No.1) and two types of wild soybean (W1 and W2) were used as experimental materials to investigate their response to shade under two light environments: natural light and 50% shade. The results showed that the specific leaf weight, leaf thickness, fenestrated tissue thickness, net photo-synthetic rate, stomatal conductance, and photosynthetic pigment content of wild and cultivated soybean were significantly lower under shade stress than under natural light. In shade, cultivated soybean showed higher variation in net photosynthetic rate, photosynthetic pigment content, spongy tissue thickness, and leaf area than wild soybean, while specific leaf weight and ratio of fenestrated tissue to spongy tissue were significantly lower than wild soybean. Wild soybean can improve its adaptation to low light conditions by maintaining Chlb content, increasing the proportion of chlorophyll in photosynthetic pigments and stimulating potential maximum photosynthetic activity as a response. The differences in the response of wild and cultivated soybean to shade conditions could provide theoretical support for future breeding of shade-tolerant soybean. [ABSTRACT FROM AUTHOR]

Objective To express recombinant Burkholderia pseudomallei (B. pseudomallei) type Ⅲ secretion system BipD protein, prepare its polyclonal antibodies and verify their immunological traits. Methods The recombinant pET-28a-BipD plasmid was generated, and the pET-28a-BipD-carried E.coli BL21 (DE3) bacteria were induced with isopropyl-β-d-thiogalactoside (IPTG) to express recombinant BipD (rBipD) protein. The rBipD was obtained by affinity chromatography using His Trap column, then mixed with Fredrick's adjuvant to immunize BALB/c mice by intraperitoneal injection in order to obtain anti-rBipD polyclonal antibodies. The immunoreactivity of rBipD was detected by Western blot assay using rabbit anti-melioidosis serum and the serum from melioidosis patients. The immunogenicity of rBipD was evaluated using Western blotting and immunofluorescence staining. Finally, rBipD was used to establish an indirect ELISA to detect serum antibodies of clinical melioidosis patients. Results The recombinant plasmid pET-28a-BipD was successfully constructed and transformed into E.coli BL21 (DE3) to induce rBipD expression with IPTG treatment. The obtained rBipD had a relative molecular weight of 36×103 and a purity of 95.4%, and had good immunogenicity and immunoreactivity. It could induce the production of specific antibodies after immunizing mice, and mouse polyclonal antibodies against rBipD were prepared with the titer of 1∶512 000. rBipD of 5.0 μg/mL produced specific immune response with the serum of melioidosis patients, but had no specific reaction with the serum of tuberculosis patients, with statistical difference (P < 0.01). Conclusion rBipD with immunological activity is successfully prepared and purified, and its polyclonal antibodies are also developed, which provide a good tool for clinical immunological diagnosis and study of immune mechanism of B. pseudomallei infection.

Metal oxides are often used as electrode materials for supercapacitors because of their high capacity， low cost， suitability for commercialization， and environmental friendliness. In this study， Mn-MOF was used as a precursor and placed in ethanol for ion exchange and etching reaction with Co（NO3）2， followed by heat treatment in air， and finally highly crystalline CoMn2O4 two-dimensional nanorod structures were obtained on a carbon cloth（CC） substrate. SEM and XRD analyses of CoMn2O4/CC prepared with different Co（NO3）2 additions and Mn2O3/CC obtained by direct heat treatment were performed， and electrochemical properties were measured by cyclic voltammetry test， constant current charge/discharge test and AC impedance test. The results show that the parent structure of CoMn2O4/CC is relatively well preserved after 0.3 g Co（NO3）2 etching， forming a nano-hollow structure， and the vertical nanorod structures grow in situ on carbon cloth after heat treatment wrapping carbon fibers uniformly and densely， ensuring high mechanical stability and electrical conductivity due to the absence of any binder addition. The electrode material has an area specific capacitance of 809.8 mF·cm-2 at the current density of 1.2 mA·cm-2 and the capacitance retention is 79.1% after 5000 cycles at the current density of 5 mA·cm-2，showing potential application prospects.

In order to study the corrosion resistance of three different superhydrophobic coatings (MZS-1, MZS-2 and ZnO@ZIF-8) on AZ91D magnesium alloy surface in 5% (mass fraction) NaCl solution. The microstructure, wettability and corrosion resistance of the superhydrophobic composite coating were tested and characterized by field emission scanning electron microscope, static contact angle tester, electrochemical workstation and salt spray tester, respectively. The results show that the corrosion of the superhydrophobic coatings does not occur until 192 h after salt spray treatment among the three types of superhydrophobic coatings, and the corrosion of the MZS-1 superhydrophobic coating is the most serious. The surface pitting of the MZS-2 superhydrophobic coating doesn't occur until 240 h later, and the contact angle is still high after salt spray treatment, so the corrosion resistance of the MZS-2 composite coating is the best.The polarization curve tests indicate that the corrosion current density of three superhydrophobic coatings are still one order of magnitude lower than that of the metal matrix after salt spray treatment for 240 h, showing excellent corrosion resistance. The superhydrophobic coating can effectively increase the corrosion resistance of metal materials.It can effectively prevent the infiltration of corrosive ions and provide long-term protection for the matrix because of its water repellency.

To exploit the difference of root nodule growth and nitrogen fixation potential of soybean in maize-soybean relay strip intercropping system, a two-year filed experiment with different nodulation characteristics soybean varieties (Gongxuan 1, Guixia 3, and Nandou 25) under different maize-soybean spacing (30, 45, 60, and 75 cm) was conducted. The results showed that the peaks of soybean nodule number and fresh weight were delayed under the intercropping system compared with soybean monoculture. The root nodule number and fresh weight of each variety under 60 cm were significantly higher than those of other spacing treatments, and were higher than those of monoculture soybean after reaching the peak stage. The differences among varieties were as follows: Nandou 25 > Guixia 3 > Gongxuan 1. Compared with soybean monoculture, nitrogen fixation potential of soybean nodules per plant before the beginning seed stage (R5) under intercropping mode was reduced. However, nitrogen fixation potential per plant of Gongxuan 1, Guixia 3, and Nandou 25 increased by 8.53%, 16.40%, and 13.70% on average in two years under 60 cm at R5 stage. The accumulation process of inclusions in infected cells of different soybean varieties was quite different. Compared with soybean monoculture, the number of bacteroids increased under 60 cm at R5, among which poly-P-hydroxybutyrate (PHB) increased, and Nandou 25 was the best. Therefore, to improve the number of soybean nodule bacteroids, PHB and nitrogen fixation potential the appropriate inter-plant row spacing (60 cm) under intercropping can increase soybean nodule number and fresh weight at R5 stage, and Nandou 25 with strong nodulation had the best effect. [ABSTRACT FROM AUTHOR]

Objective: This study focused on investigating the enzymatic characteristics of D-lactate dehydrogenase (D-LDH) in Leuconostoc citreum KM20. Methods: The D-lactate dehydrogenase gene (LDH) from L.citreum KM20 was cloned and expressed to construct expression plasmid, and then transformed into Escherichia coli BL21 (DE3) for overexpression. Results: The enzymes encoded by LCK_00027 and LCK_00222 were purified by Ni-NTA column affinity chromatography with molecular mass of 40.0 kDa and 38.5 kDa, respectively. The specific activities were 2.18 U/mg and 153.10 U/mg, respectively. The optimal pH and temperature for pyruvate reduction were 8.0 and 40 ℃, respectively, while for the LCK_00222 encoding enzyme lactic acid oxidation the values were 12.0 and 30 ℃, respectively. The two enzymes had high activities toward oxaloacetic acid, sodium phenylpyruvate, and 2-oxoglutaric acid. Ca2+, Cu2+, and Na+ promoted the activity of the two enzymes, whereas Zn2+ and SDS inhibited. In addition, the Kcat/Km of LCK_00027 and LCK_00222 to pyruvate were 6.04×102 L/(mol·s) and 2.28×104 L/(mol·s), respectively. The Kcat/Km of LCK_00222 encoding enzyme to D-lactic acid was 65.0 L/(mol·s). Conclusion: D-LDH-1 and D-LDH-2 are key enzymes catalyzing the synthesis of D-lactic acid in Leuconostoc citrate.

[Objective] To study the physiological response of sunflowers to broomrape parasitism and the related metabolic pathways, as well as understanding the molecular mechanism of sunflower resistance to broomrape parasitism. [Methods] The broomrape-resisant (s41) and -sensitive (s26) sunflowers were used as the testing materials. Transcriptome analysis of 4 samples under the condition of parasitic stress was carried out, and physiological verification analysis of key metabolites was carried out. [Results] (1) Under inoculation, the plant height and root number of susceptible materials were affected significantly, and some of them were even unearthed, while the resistant materials had no obvious changes, and only a few were parasitized. (2) The number of DEGs was 6 362, 6 609, 5 490 and 5 469 by screening the differential genes among the samples. GO analysis showed that the four comparison groups, namely s26-s41, s26CK-s41CK, s26-s26CK, and s41-s41CK, had the most differential genes in biological processes, followed by cellular components, and less in molecular functions. KEGG analysis showed that infection had a great influence on plant signal transduction, biosynthesis of secondary metabolites, lipid metabolism, amino acid metabolism, and sugar metabolism in sunflowers. (3) Physiological analyses found that the phenylalanine deaminase, cinnamyl alcohol dehydrogenase, glutathione, total phenols, and salicylic acid showed an upward trend, indicating that the stress tolerant system was activated under parasitism. However, the trend of the physiological indicators of the sensitive and tolerant materials were different. Also, the genes controlling the physiological responses were differentially expressed. [Conclusion] It was found that inoculation with broomrape significantly affected the plant height and root volume of the susceptible materials, while the resistant materials were not affected. The resistant materials were enhanced in root lignin synthesis, antioxidant enzyme activity, and the expression of key genes of phenylpropanoid metabolism, salicylic acid and signaling pathway, and hence increased the resistance to broomrape.

The seasonal drought is a serious problem because of the unevenly distributed rainfall during the years in the Yangtze River basin. To construct multi-cropping patterns of intercropping with drought avoidance and disaster reduction as the main body is the fundamental way to realize the efficient utilization of water resources. Therefore, we carried out dryland multiple cropping patterns evaluation in test in the Yangtze River (Sichuan, Hubei, Hunan, Jiangxi, and Jiangsu) from 2016 to 2020, the cropping patterns was set as wheat-summer maize (C1), wheat-summer maize summer soybean (C2), forage rape // -spring maize/summer soybean (C3), and potato-spring maize/summer soybean (C4) in Sichuan. Rape-maize summer soybean (B1), forage rape // -spring maize spring soybean (B2), and potato / spring maize / summer soybean (B3) in // Hubei; rape-maize su // mmer soybean (N1), forage rape-spring maize/summer soybean (N2), and forage rape-spring maize spring soybean // -autumn soybean (N3) in Hunan; potato/spring maize/summer soybean (X1), rape-maize summer soybean (X2), ryegrass //-spring maize/summer soybean (X3), and ryegrass-spring maize spring soybean (X4). Wheat // -fresh maize/fresh maize (S1), wheat-fresh maize/fresh soybean (S2), fresh broad bean/fresh maize-fresh maize (S3), and fresh broad bean/fresh maize-fresh soybean (S4) in Jiangsu. We compared the characteristics of supply-demand equilibrium, the paddy of the overall productions and the water benefits of different cropping patterns with the AquaCrop model. These results showed that the water satisfy rate of C4 was 5.28%, 2.91%, and 6.00% higher than C1, C2, and C4, and the paddy of the overall production was 71.2%, 49.3%, and 25.6% higher, respectively, and the water benefit was 329.29%, 123.42%, and 45.52% higher in Sichuan. The water satisfy rate of B3 was 3.99% and 3.51% higher than B1 and B2, and the paddy of the overall production was 36.8% and 25.8% higher, and the water benefit was 295.60% and 69.01% higher in Hubei, respectively. The water satisfy rate of N2 was 9.08% and 2.93% higher than N1 and N3, and the water benefit was 58.47% and 183.33% higher in Hunan, respectively. The water satisfy rate of X1 was 7.94%, 6.70%, and 4.05% higher than X2, X3, and X4, and paddy of the overall production was 112.4%, 152.5%, and 116.8% higher, respectively, and the water benefit was 97.03%, 126.14%, and 77.68% higher in Jiangxi, respectively. The water satisfy rate of S4 was 7.94%, 6.70%, and 4.05% higher than X2, X3, and X4, and paddy of the overall production was respectively 35.4%, 17.5%, and 12.6% higher, and the water benefit was 60.25%, 14.93%, and 45.56% higher in Jiangsu, respectively. Potato-spring maize/summer soybean in Sichuan, potato/spring maize/summer soybean in Hubei, forage rape-spring maize/summer soybean in Hunan, potato/spring maize/summer soybean in Jiangxi and fresh broad bean/fresh maize-fresh soybean in Jiangsu were the appropriate cropping patterns that can improve the water supply-demand equilibrium, paddy of the overall production, and water benefit. To avoid seasonal drought and achieve annual high yield, the appropriate multiple cropping patterns of intercropping should be selected depending on the rainfall conditions in the dryland of the Yangtze River basin. [ABSTRACT FROM AUTHOR]

In order to solve the problems of difficulty and low efficiency in selecting water resources allocation scheme, a multi-attribute Decision-making method of water resources allocation scheme based on Pythagorean fuzzy set with interval value and PROMETHEE algorithm is proposed in this paper. Firstly, the interval fuzzy decision matrix of decision-makers is constructed, and the weights of decision-makers and attributes are determined by the distance of relative proximity coefficient method, entropy method and Pythagorean fuzzy number. Secondly, the comprehensive weight and IVPFWA operator are used to aggregate the decision matrix of each decision-maker into the comprehensive matrix, and then the final ranking results of water resources allocation schemes are obtained by PROMETHEE method. Finally, the algorithm used in this paper to select the optimal water resources allocation plan in City S as a case, and through comparison with the results of other methods, it finally shows that the method in this paper can accurately determine a reasonable water resources allocation plan, and the method is effective and reliable. [ABSTRACT FROM AUTHOR]

Recommender systems can effectively alleviate the problem of information overload caused by the rapid development of the Internet. However, the occurrence of shilling attacks restricts the healthy development of recommender systems. Therefore, how to detect shilling attacks accurately and efficiently is an important problem in the field of recommender systems security. The existing detection methods usually design hand-crafted detection features based on expert knowledge or automatically learn features from a single perspective using deep learning, then the attack users are identified according to the extracted features by hard classification, resulting in the poor detection performance. By automatically learning features from multiple perspectives and introducing a hesitant fuzzy decision, a novel detection method based on CNN and hesitant fuzzy set was proposed and named CNN-HFS. Firstly, for each user, three behavior matrices were extracted from the perspectives of rating, preference and rating time, respectively. To reduce the influence of data sparse, these matrices were scaled by bicubic interpolation to correspondingly obtain a dense rating matrix, a dense preference matrix and a dense time matrix. Next, each scaling matrix of users was regarded as an image, and three different CNN classifiers were trained based on these scaling matrices in three different views respectively. For each user, three membership degrees to the classifier of attack users were calculated. Finally, a fuzzy hesitant set was introduced to make a comprehensive decision, and the attack users were identified according to the decision results. To validate the effectiveness of the proposed CNN-HFS, the extensive experiments were conducted on the MovieLens 1M and Amazon datasets. The evaluation metrics of precision, recall and F1-measure were used to compare the proposed method with SVM-TIA, CoDetector, CNN-SAD, SDAEs-PCA, CNN-R, CNN-P and CNN-T. The experimental results showed that the proposed method is superior to seven baseline methods in terms of three detection metrics and achieves an excellent detection performance under various attacks. [ABSTRACT FROM AUTHOR]

Cancer is a form of inflammation, which is different from common inflammation in that it is uncontrollable and difficult to identify pathogenic microorganisms. Most tumors are related to specific pathogenic microorganisms, especially viral infections. The relationship between gliomas and human cytomegalovirus (HCMV) infection has been debated for decades. This article puts forward the author's own point of view as an interpretation on the basis of objectively expounding the positive and negative points of view, and put forward a further solution to the dispute, for clinical reference. [ABSTRACT FROM AUTHOR]

The shape memory effect of Fe-Mn-Si based alloys could be significantly improved by thermo-mechanical treatments. In this work, the cast Fe-Mn-Si based alloy was hot forged, 20% cold rolled and solution treated, followed by annealing at 1073 K for different time on some specimens deformed by 10% at room temperature, and the effect of annealing time of thermo-mechanical treatments on the microstructures and shape memory effect of the Fe-Mn-Si based alloy was studied with the help of backscattered electron microanalysis (EBSD), RGM-4300 universal testing machine, differential four-terminal resistance method and bending method.Results show that the recovery strain of the solution-treated Fe-Mn-Si based alloy is 4.1%; when the annealing time of thermo-mechanical treatment is 10 min, the recovery strain is remarkably improved to 5.3%; As the annealing time of thermo-mechanical treatment is further prolonged, the recovery strain decreases; when the annealing time of thermo-mechanical treatments is 180 min, the recovery strain decreases to 4.9%. As the annealing time of thermo-mechanical treatments prolongs, the fraction of annealing twins increases, while the density of stacking faults decreases, which leads to the ability of facilitating stress-induced ε martensitic transformation and suppressing plastic glide weakening. This is the main reason why the recovery strain of the Fe-Mn-Si based alloy decreases with the annealing time of thermo-mechanical treatments prolonging.

The end face meshing worm drive with tapered roller envelope has many simultaneous meshing tooth pairs and can eliminate clearance. According to the gear meshing principle and differential geometry principle, the meshing mathematical model of the transmission pair is established, the worm tooth surface equation and meshing function are deduced, and the meshing performance calculation formula is obtained. Matlab software is used to analyze the effects of small end radius, throat diameter coefficient and half cone angle of cone on the meshing performance evaluation parameters of the transmission pair induced normal curvature, lubrication angle, relative entrainment speed and self rotation angle. The analysis results show that the transmission pair has good meshing performance.

Target recognition and temperature extraction of the typical component of gas insulated switchgear (GIS) are the key to realizing the infrared intelligent detection of equipment heating state. In this paper, an improved YOLOv4 algorithm based on convolutional block attention module (CBAM) is proposed to achieve rapid target detection and hot spot temperature extraction of GIS bus, disconnector and other components. Firstly, the original infrared images are acquired at a substation site, and an infrared dataset containing typical GIS components is constructed by sharpening the images and marking components. Then, the deep separable convolutional network is used to reduce the amount of model parameters, and the CBAM is integrated to optimize the recognition ability of the model, on the basis of which a GIS infrared component target rapid detection algorithm with improved YOLOv4 is constructed. Finally, the gray-scale difference method is used to extract the temperature value of the hot area for the detected typical target components of GIS. The results show that the proposed algorithm can achieve a recognition speed of 31.5 frame per second and an recognition accuracy of 82.3% on the GIS infrared feature dataset, which is significantly better than other target algorithms. The error between the calculated value and the measured value of temperature rise of GIS components is within ±1℃. The algorithm proposed in this paper can be deployed in edge intelligent terminals such as unmanned aerial vehicles and inspection trolleys to achieve refined identification and rapid diagnosis of the temperature rise status of on-site GIS equipment, thus improving the digitalization and intelligence level of health management of GIS.

[Purpose/Significance] The research paradigm of digital humanities provides an opportunity for researchers to conduct evidence-based research based on second-hand resources. The second-hand evidence in the evidence-based digital humanities research mainly refers to the secondary evidence obtained by researchers through analysis of the original literature records. Academic papers are such an example of second-hand evidence and analysis of these papers enables us to be focused on the exploration, discussion and comprehension of the specific evidence. [Method/Process] This paper aims to shed light on the theoretical basis related to second-hand evidence based digital humanities research, and conduct an empirical analysis with Dunhuang wooden and bamboo slips of Han Dynasty. Through the coding analysis of 287 relevant research papers downloaded from the CNKI database, the reliability and validity of the research were tested, and a comprehensive analysis of the category system was conducted. On this basis, two independent coders systematically coded all academic papersby, and a coding system was formed with reliable reliability and validity. This coding system provided us a foundation to summarize the procedure of extracting the second-hand evidence from academic papers in the digital humanities research. [Results/Conclusions] This paper issued a three-stage and five- link procedure for second-hand evidence based digital humanity research. The "three stages" refer to the systematical literature retrieval, category formulation and comprehensive analysis of the second-hand evidence elements and the five links include evidence retrieval, reliability test, validity test, category construction and evidence element synthesis. The procedure developed by this research is expected to shed light on the knowledge organization of ancient literature works and lay a foundation for the digital humanities research based on the secondary resources like academic papers. Thus, based on the above procedure, the researchers in the digital humanities area are able to extract fruitful second-hand evidence from secondary resources (academic papers, for example) instead of acquiring initial evidence. This procedure may benefit the evidence-based digital humanity research because it is always a challenging task for individual researcher to access the initial research material like Dunhang wooden and bamboo slips of Han Dynasty. In summary, the paradigm constructed in this study has certain theoretical reference and practical guidance value for the construction of evidence-based digital humanities subject, and academic and discourse system. Thus, it is expected to benefit the construction of independent knowledge system of evidence-based digital humanities with Chinese characteristics.

Objective To explore the expression of 3-hydroxymethylglutaryl-CoA synthase 2 (HMGCS2) and its correlation with the clinicopathological characteristics of patients with bladder cancer. Methods The GEO database was used to screen genes that were significantly differentially expressed between muscle invasive bladder cancer and non-muscle invasive bladder cancer. The survival analysis of the screened public differentially expressed genes was performed by gene expression profiling interactive analysis (GEPIA). The Metascape database was used for the functional enrichment analysis of HMGCS2 and its related genes. The expression of HMGCS2 was detected with immunohistochemical staining in clinical samples from patients with bladder cancer. Chi-square test was used to analyze the relationship between the expression of HMGCS2 and the clinicopathological characteristics, and Cox regression analysis was adopted to verify the prognostic efficacy of HMGCS2. Results The transcriptome data of the GEO database showed HMGCS2 had significantly lower expression in muscle invasive bladder cancer compared with non-muscle invasive bladder cancer (7.42±2.51 vs 9.38±2.78, P < 0.05). The survival analysis of the GEPIA database showed that patients with high expression of HMGCS2 had better prognosis (overall survival: HR=0.6, P=0.028; disease progression-free survival: HR=0.59, P=0.036); KEGG pathway analysis and GO functional enrichment analysis showed that HMGCS2 might be involved in fat metabolism, cell apoptosis and platinum resistance, and exerted effect on the signal transduction of the mTOR pathway. In addition, the Chi-square test showed the expression of HMGCS2 was significantly related to the T stage (P < 0.001), tissue grade (P=0.006), patients' overall survival status (P < 0.001) and patients' disease-free survival status (P < 0.001); Univariate Cox regression analysis showed that HMGCS2 was related to the patients' overall survival rate and the disease progression-free survival rate (OS: HR=0.104, P < 0.001; DFS: HR=0.155, P < 0.001); multivariate Cox regression analysis indicated that HMGCS2 was an independent predictor of the prognostic risk of patients (OS: HR=0.181, P < 0.001; DFS: HR=0.312, P < 0.001). Conclusion HMGCS2 is lowly expressed in muscle invasive bladder cancer, and its low expression is closely related to the poor prognosis of patients.

Objective To screen the influencing factors of liver cirrhosis with spontaneous bacterial peritonitis (SBP) so as to establish and verify a diagnostic model of cirrhosis with SBP. Methods A total of 7 461 patients with liver cirrhosis were collected from 2 Grade-A hospitals in Chongqing (Hospital A and B) between July 2015 and December 2019. According to the occurrence of SBP during hospitalization, they were divided into SBP (n=1 173) and non-SBP (n=6 288) groups. A total of 3 776 patients (70%) from Hospital A were randomly selected as the training set, while the remaining 1 619 patients (30%) and the 2 066 patients from hospital B were subjected as the internal and external validation sets respectively. Univariate and logistic analyses were used to screen variables, and logistic regression, random forest (RF), decision tree (DT) and XGBoost models were subsequently established using the training set. Then, the optimized logistic regression model was built on the basis of the above 4 models. Finally, the 5 models were applied in the internal and external verification sets for evaluating and comparing the diagnostic value of different models for cirrhosis with SBP. Results The machine learning algorithm suggested that the 7 common influencing factors with significance in all models were as follows: decompensation stage (OR=5.354, 95%CI: 3.770-7.803), lymphocyte percentage (OR=0.951, 95%CI: 0.939-0.962), total bilirubin (OR=1.003, 95%CI: 1.002-1.004), abnormal C-reactive protein (OR=1.626, 95%CI: 1.310-2.017), international normalized ratio (OR=1.346, 95%CI: 1.091-1.681), prealbumin (OR=0.990, 95%CI: 0.987-0.993) and model for end stage liver disease (MELD) score (OR=1.038, 95%CI: 1.015-1.063). The AUC of the internal verification of the optimized logistic model was 0.860, with a sensitivity of 0.872 and a specificity of 0.719; while the corresponding values of the external verification were 0.818, 0.662 and 0.812, respectively. Delong test showed that there was no statistical difference in AUC between the optimized logistic regression model and the other models with favorable performance. Conclusion The risk prediction models established by machine learning algorithm for liver cirrhosis complicated with SBP have high diagnostic value. Among them, the optimized logistic regression model has performed well in both internal and external verification, and is able to provide reference for clinical diagnosis of SBP.

Objectives The warship formation wireless IP network bandwidth is limited and time-varying. In order to meet the cross-platform task operation time limit requirements in the formation of combat application, it is necessary to study the cross-platform task scheduling algorithm under the network bandwidth constraints.Methods In this paper, a task scheduling model based on the wireless IP network of warship formation is proposed. A communication mode entailing a "task initiator" and "task responser" is adopted to realize the task scheduling of "earliest deadline first (EDF) + first come first serve". The extended EDF algorithm is proposed. Based on the traditional single-platform single-processor realtime scheduling algorithm, it can be applied to ship formation, transforming the calculation of task execution time from processor time to network time, deducing the judging condition of task scheduling ability, and conducting tests to verify the proposed method.Results The results show that the scheduling capability of a cross-platform task set for warship formation can be calculated through the construction of a test network environment.Conclusions Use of the theoretical model and algorithm proposed in this paper is well implemented, and hold an important value for guiding the task planning and scheduling of warship formation wireless IP networks.

In the Synthetic Aperture Radar (SAR) remote sensing imagery of complicated scenes (especially urban scenes), there are a large number of lines and surfaces, such as roads in urban areas and the surfaces of buildings. These microwave-signal-scattering features have strong directivity. Traditional SAR acquires the scattering information of a scene from a single observation, and traditional imaging algorithms are based on the point target model, which makes the main features of the lines and surfaces in traditional SAR images appear as a series of strong scattering points rather than line-scattering and surface-scattering features. This outcome ultimately causes the target to be discontinuous in the SAR image, thus making the SAR image difficult to interpret. Therefore, in this study, we conducted an in-depth and meticulous investigation of the SAR imaging mechanism for lines and surfaces by establishing a parametric echo model of typical lines and triangular surfaces. Based on the proposed parametric model, we performed parametric imaging of these lines and surfaces. Based on our results, we propose a parametric imaging method, in which the typical lines and surfaces are classified and determined based on Bayesian theory and the proposed parametric model. Then, an SAR image can be obtained that effectively characterizes the scattering features of the line and surface targets by visual imaging, which effectively facilitates SAR image interpretation. The results of our numerical simulation experiments verify the validity of the proposed method.

In order to meet the needs of high-altitude, long-endurance, high mobility, functional and economic requirement for the future unmanned aerial vehicle(UAV), advanced composite materials have been increasingly applied in UAVs at home and abroad, and even many all-composite UAVs are manufactured. However, there are still some gaps in the proportion and technical level of composite materials used in UAVs in China compared with foreign countries. The cost of composite parts is one of the main factors restricting its application. This paper introduces the development process of UAV at home and abroad, and summarizes the application of composite materials on UAVs. Some key technologies and development trends of UAV composite materials are proposed. Some questions and suggestions are raised on the application of domestic composite materials on drones. For accelerating the application of composite materials in UAV industry in China, it is necessary to design the composite structure based on the process feasibility and stability with introducing foreign automation technology to reduce composite structure cost, actively develop various liquid forming technology, bag vacuum only-out of autoclave(BVO-OoA) materials and technology, and improve the traditional moulding technology research.

In this paper, the main vegetative growth indexes of chrysanthemum such as height of plant, number of ground stem diameter, number of branches and the main reproductive growth indexes of chrysanthemum such as number of flower, weight of flower, diameter of flower, thickness of flower which were introduced and cultivated at different altitude in Baoxing of Sichuan Province were measured by field trials and the main quality indexes of the chrysanthemum samples such as content of Chlorogenic acid, contents of Luteolin and Isochlorogenic acid A were measured by laboratory analysis. The measured data were prossed by variance and correlation analysis to find the difference of plant growth and quality for medication of chrysanthemum which were introduced and cultivated at different altitude at high altitude area. The results showed that the vegetable growth index such as height of plant,the reproductive growth indexes such as number of flower, weight of flower, diameter of flower, thickness of flower and the quality indexes such as content of Luteolm and Isochlorogenic acid A of chrysanthemum were affected significantly by the elevation gradient at high attitude area(P>0.05). The vegetable growth indexes such as diameter of groung stem, number of braches and the quality index such as content of Chlorogenic acid of chrysanthemum were affected insignificantly by the elevation gradient at high attitude area (P<0.05). The vegetable growth index such as height of plant and the quality indexes such as number of flower, diameter of flower of chrysanthemum had a significant correlation with the elevation gradient at high attitude area (P<0.05). The elevation gradient at high attitude area had a significant effects on the plant growth of chrysanthemum exclude a few vegetable growth indexes such as the number of braches and diameter of ground stem. Within a certain range of altitudes(2 051--2 405 m) at high attitude area, the elevation gradient had insignificant effects on the quality formation of chrysanthemum. The quality of chrysanthemum all met the medicinal condition within the altitude of 2 051-2 598 m according to the minimum limits standard of active ingredients of chrysanthemum in the "Pepole's Republic of China Pharmacopoeia (2010 edition)" and the chrysanthemum had a best quality for medication which were introduced and cultivated around the altitude of 2 329 m. This study provided a theoretical basis for the introduction and cultivation of chrysanthemum for medication in the high altitude area. [ABSTRACT FROM AUTHOR]

A certain measurement system for flexible joint’s pivot point drift has been studied in this paper. The detection system consists of camera bracket,signposts,image processing module,pivot point calculation module,result processing module,industrial camera,data interface,industrial computer and some other auxiliary devices. Two signposts are fixed on the line at a certain angle to the center line of the swinging body to be measured. When the signposts swing together with the swinging body,the industrial camera will take continues samples from it. Then the samples will be transferred to the industrial computer by the data interface. After that the image processing module will get the signposts ’position in the measurement system plane coordinates by images denoising, background subtraction and signposts positioning. With this information the pivot point calculation module will calculate the average pivot point of two different samples to approach the momentary pivot position while the swinging body swings according to the mathematic model. The result processing module will record and visualize the pivot point movement trajectory. The precision of this measurement system is about 0. 5% which has been checked by simulation and proved by test.

Peanuts were hydrolyzed step by step with various enzymes to prepare protein powder. Using peanuts as raw materials, protein extraction rate response value, enzyme addition amount, temperature, and pH as experimental factors, were used to establish a data model to optimize the extraction process with response surface. The protein powder prepared under this condition was compared with the protein powder prepared by water extraction method, single enzyme extraction method and commercially available protein. The particle size distribution, solubility, emulsification and surface hydrophobicity of protein powder extracted by compound enzyme were studied. The results showed that the optimal enzymatic hydrolysis conditions of the complex enzyme were 1.8% enzyme addition, 55 ℃ reaction temperature, and pH 9.2. Under these conditions, the protein extraction rate reached 89.21%. The particle size distribution of the protein powder prepared by the complex enzymes was uniform, and the particles were smaller, indicating that the protein solubility and emulsification were significantly improved.

With the continuous improvement of the performance of unmanned aerial vehicles and the extensive use of tactical methods, the cooperative operation of unmanned aerial vehicles (UAV) swarm has brought new challenges to the current air defense system. By combing and analyzing the application cases of UAV swarm warfare in recent years, this paper summarizes the characteristics of current UAV swarm warfare application, and explains the necessity and urgency of developing anti UAV swarm warfare command and control system. In addition, this paper analyzes the current situation of the command and control system of anti UAV swarm warfare in the world's military powers, and on this basis, puts forward some enlightenment suggestions for the development of the future anti UAV swarm warfare command and control system.

The main functional components and biological activities of Grifola frondosa were reviewed, and the existing problems and future research directions were also discussed.

研究旨在透過文獻分析，回顧過去國外科學教育領域中的系統思考能力相關研究，歸納其適用年級與學科、系統思考能力分析架構，以及評量與教學的趨勢並提出建議。研究者於 SCOPUS 與 Web of Science 資料庫搜尋 2000 年到 2019 年的英文期刊論文，經有系統篩選後，針對 20 篇文章進行分析。分析結果發現，系統思考的研究對象以國、高中生為主，有些研究以小學生為對象，其學習成效主要在基礎系統思考能力的獲得。涉及的學科領域則以生態、生物以及地科最為常見，所回顧的文獻中並沒有應用於物理領域，顯示系統思考並非適合融入所有自然科學領域。對於系統思考能力的分析架構，共可歸納出組件連結模式、階層發展模式、複雜系統模式及內容導向模式等四種類型。在系統思考量測方法上許多研究採多元評量，最常被採用的是開放性試題與晤談。至於教學策 略，許多研究都採取了多元的教學活動，且多半包含知識統整活動，部分研究則採用電腦模擬進行教學。由於文獻中已有較為完整的系統思考能力分析架構，未來建議可以進行學習進程或是縱貫性研究，並將資訊科技應用於系統思考評量上。最後，我們對系統思考在教學與評量的實務建議包含有：教學上應優先嘗試初階的組件連結模式；教學方法則以明示教學法協助學生建立系統思考概念鷹架、嘗試採用多元的活動設計、引進科技輔助以及引導學生廣泛地將系統思考應用於各種生活情境中；評量方面則是建議以概念圖、概念繪圖及概念填空題進行，容易實施且能獲得較多訊息。 The aim of this research was to review past empirical studies about systems thinking in science education in order to understand the applied grade levels and subject areas, the analytical framework for systems thinking, and its trends in teaching and assessment. We searched for research articles published from 2000 to 2019 in the SCOPUS and Web of Science database and found 20 qualified studies. The results showed that most studies were conducted at junior high schools and senior high schools. Some studies were conducted at the elementary school level and found gains in fundamental competence of systems thinking. The most frequently applied subject areas were ecology, biology, and earth science. In this review, no studies applied systems thinking in physics. This indicates that systems thinking might not be suitable for all subject areas of science. In terms of the analytical framework for systems thinking, different studies invented different frameworks. The common features of the systems thinking framework include components recognition, as well as the mutual interactions and influence of different components. Regarding assessment for systems thinking, some studies used multiple assessments, and the most commonly used types of assessments were open-ended questions and interviews. Many studies adopted a variety of teaching activities and included knowledge integration activities. Some studies also used computer simulations to support learning. For future research, we suggest investigating the learning progression of systems thinking or conducting longitudinal studies by applying the available analytical framework of systems thinking. Future studies can also apply computer technology in the assessment of systems thinking. Finally, we offer some specific suggestions for teaching and assessments of systems thinking.

BACKGROUND At present, the content of Se in soil is mainly determined by atomic fluorescence spectrometry, which has disadvantages such as large usage of acid and relatively complex pretreatment. Determination of high content of Se requires high dilution, which expands the analysis error. OBJECTIVES To establish a method for the determination of Se and other elements in Se-rich soil samples by wavelength dispersive and energy dispersive X-ray fluorescence (WD-ED XRF). METHODS WD-ED XRF was used to determine 17 major and minor elements such as Se in Hubei selenium-rich soil samples with powder pellet. While 10 elements were analyzed by WD-XRF, As, Cu, Rb, Sr, Zr, Ba, Ni were analyzed by ED-XRF, which significantly reduced the measurement time. RESULTS By mixing different certified reference materials in proportion to configure mixed certified reference materials, the problem of insufficient content of the existing Se reference materials in the range of 5-72μg/g was solved. For the determination of high content Se, the relative standard deviation was less than 10%, and the RSD of high content Se sample was less than 0.70%, through the precision and accuracy assessment. CONCLUSIONS The proposed method satisfies the quantitative analysis of soil samples with Se content greater than 3.00μg/g, and provides the quantitative or approximate quantitative analysis results of 16 major and minor elements.

BACKGROUND Selenium is an essential micronutrient for humans. The spatial heterogeneity of selenium in soil is the main cause of various diseases and environmental problems. Selenium in soil is unevenly distributed across the globe, with most soils being low in selenium. Globally, the average selenium content in soil is 0.4mg/kg, while it is 346-2018mg/kg in typical high-selenium areas. Thus, accurate analysis of selenium in soil is of great significance in research on seleniferous soil. The reasonable use of reference materials can aid in the effective monitoring of the quality of analysis. OBJECTIVES To summarize the status of research on selenium in soil, and the development of the corresponding analytical methods and reference materials. METHODS This article describes the distribution characteristics, speciation, and migration and transformation characteristics of selenium in soil. Furthermore, the methods for extracting selenium speciation in soil, the progress of research on selenium content analysis technology, and the status of the development of soil selenium reference materials in recent years are summarized. RESULTS Because of limited advancements in the development of analytical techniques, research on the mechanism of migration and transformation is still incomplete. The emergence of sequential extraction techniques provides a new way to study the distribution, migration, and transformation of soil selenium speciation. However, this method is still under development and has many shortcomings, such as inadequate selectivity and inevitable speciation transformation. Atomic fluorescence spectroscopy is the mainstream approach for the analysis of selenium content in soil, especially in China. Mass spectrometry, with high precision and a low detection limit, and synchrotron radiation X-ray technology, with in-situ speciation analysis capabilities, offer significant advantages in the analysis of trace and ultra-trace elements and speciation analysis. There is a significant gap in the research on reference materials with gradient content and certified speciation content. CONCLUSIONS Methods with a low detection limit, high sensitivity, and matrix interference resistance are urgently needed. The combined application of sequential extraction, mass spectrometry, and X-ray fluorescence can promote research on selenium in soil. Moreover, related certified reference materials with gradient content and certified speciation content are in short supply.

BACKGROUND Polymetallic nodules are predominant in deep sea sedimentary mineral resources due to the enrichment of many critical metals. Polymetallic nodules are loose and porous, which is the critical material feature that contributes the adsorption of trace metals from seawater and pore water and then enrichment and mineralization. Therefore, specific surface area (SSA) is one of the key factors for studying the ore-forming process of polymetallic nodules. At present, the methods for SSA determination are well-developed. However, they are less applied in the analysis of the specific surface of polymetallic nodules, and the pretreatment conditions are not constant according to various research targets. OBJECTIVES In order to explore the pretreatment conditions for the BET SSA analysis of polymetallic nodules, and provide necessary parameters for the study of the enrichment of trace metals in polymetallic nodules. METHODS Polymetallic nodules from the Atlantic, Indian, and Pacific oceans were collected. The pretreatment conditions including temperature, duration, and particle size for SSA analysis of polymetallic nodules were studies by applying temperature programming, heating accumulation, and particle size comparing methods. RESULTS The results showed that the analysis values of SSA reached plateau when the heating temperature ranged from 210℃to 350℃. The analysis values of SSA remained constant after heating for 3 hours by a step of 1 hour at 210℃. The SSA values of samples with a size of several millimeters were 1.027-28.535m2/g higher compared with those of the same samples crushed into microns. CONCLUSIONS Reliable SSA values can be obtained when the polymetallic nodules with sizes of several millimeters are heated in a vacuum system for 3 hours at 210℃, which is the pretreatment condition for analyzing SSA of mineralization-related polymetallic nodules.

BACKGROUND Before analyzing the carbon isotopes of n-alkanes by gas chromatography-gas isotope mass spectrometry (GC-IRMS), it is necessary to pre-separate and enrich n-alkanes and isoparaffins in saturated hydrocarbon samples. Whether the carbon isotope fractionation of n-alkanes occurs is the key for the high-precision analysis of the carbon isotope ratio. OBJECTIVES To determine isotopic fractionation characteristics for n-alkanes during column chromatography and molecular sieve separation. METHODS Saturated hydrocarbon components were extracted with a 500mg/3mL SPE silica gel column using 2mL n-pentane. After separating by a 5Å molecular sieve and extracting by a mixture solvent of cyclohexane and n-pentane, n-alkanes were concentrated and analyzed by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). RESULTS During column chromatographic separation, the carbon isotope ratio of most n-alkanes differed from -0.2‰ to 0.2‰. When n-alkanes was not completely complexed by 5Å molecular sieve, the uncomplexed alkane carbon isotope was about 0.7‰ heavier, and weak carbon isotope fractionation occured, but it did not affect the eluted n-alkanes carbon isotope ratio. Eluted with cyclohexane-n-pentane mixed solvent, the carbon isotope values before and after the elution differed from-0.2‰ to 0.5‰, and eluted in the same way for the second time, the difference between the eluted n-alkanes carbon isotope and simulate sample was between -0.3‰ and 0.2‰. Analyzing the carbon isotope ratios of n-alkanes with different recoveries (>20%), the difference between carbon isotopes of n-alkanes before and after pretreatment was within 0.3‰. It was found that when the recovery was as low as 20%, the carbon isotope ratios did not undergo significant fractionation. CONCLUSIONS The column chromatography-5Å molecular sieve adsorption and mixed solvent elution method is suitable for the analysis of carbon isotope ratios of normal alkanes, which yields a recovery greater than 20%.

Wavelength Division Multiplexing (WDM) system has been evolving and upgrading in the direction of high speed, long distance and large capacity. In recent years, with the maturity of high-speed optoelectronic devices, the research and application of beyond 400 Gbit/s has made a rapid progress. Based on the technical status and requirements of 800 Gbit/s transmission systems, this paper discusses the key technical problems, sorts out the latest developments in standardization research. The evolution and application of 800 Gbit/s optical systems is further discussed.

Wavelength Division Multiplexing (WDM) system has been evolving and upgrading in the direction of high speed, long distance and large capacity. In recent years, with the maturity of high-speed optoelectronic devices, the research and application of beyond 400 Gbit/s has made a rapid progress. Based on the technical status and requirements of 800 Gbit/s transmission systems, this paper discusses the key technical problems, sorts out the latest developments in standardization research. The evolution and application of 800 Gbit/s optical systems is further discussed.

Since the Kingdom of Prussia, Germany has experienced several educational reforms and is an important source of alternative education in the world. This study focuses on two representative alternative schools in Germany, including the Jenaplan School and the Montessori School, which originated in the classical education reform stage but re-started after the reunification of the two Germanys. On the one hand, this study captures the core spirit and school profiles of the two schools through analyzing relevant literature and school documents; on the other hand, the study also tries to apprehend the characteristics of the two schools through field observations in schools, and dialogues with school principals, teachers, and students. Finally, the study emphasizes that, schools should be a community of life and learning which is constructed through the creation of the school atmosphere, space layout, festivals and celebrations, and through the establishment of educational relationships, and mixed-age learning form. Besides, student should be the real subject of his learning. School can actively promote students’ awareness and control over self-learning through open curriculum designs, self-directed learning processes, and self-monitoring of learning results. This study aims to provide various related designs for schools to reference. It also encourages practitioners to think deeply about the actual educational implications, and create new alternative education possibilities under their respective conditions.

OBJECTIVES Ion-adsorption type rare earth ore is extremely important in China and rare in the world. It is China's dominant mineral resource. At present, all the rare earth elements in the existing REE reference materials are oxide minerals, not ion-adsorption type, and cannot be exchanged with strong electrolytes. These reference materials cannot be used to monitor the leaching process of ion-adsorption type REE. METHODS The samples were collected from the typical ion-adsorption type REE weathering crust in Jiangxi Province. After being dried and ball-milled to 200 mesh, they were mixed for 1.5h. The contents of rare earth elements in the ionic phase were analyzed to test the homogeneity by ammonium sulfate leaching and inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS Results showed that the F values for the variance test were less than the threshold, which indicated a good homogeneity. The stability of monitoring samples was tested 4 times in two years, and no statistically significant changes were observed, indicating good stability of the samples. An accurate and reliable leaching analytical method was used in 8 technologically significant laboratories to finalize the contents of ionic phase rare earth elements. The determined values of nine monitoring samples were given by statistical calculation, including weighted average value and total uncertainty results which were from uncertainties in certified values, between-bottle homogeneity and long-term stability. These nine monitoring samples have certified values of 15 ionic phase rare earth elements except Sc. CONCLUSIONS The reference materials can be used to monitor the leaching process and provide metrological support for the analysis of rare earth elements in ionic phase during the evaluation and effective utilization of REE mineral resources.

BACKGROUND At present, the major elements in silicate samples are generally determined by X-ray fluorescence spectrometry with fusion sample preparation. Not only can the single element determination results not exceed the limit, but also the percentage sum must meet the requirements of sum quality (99.3%-100.7%). However, for the analysis of mineralized samples, due to the high content of trace elements, it is often not possible to meet the requirements of sum quality. The wavelength and energy dispersive X-ray fluorescence spectrometer are fully utilized. The advantages of the determination can make the analysts to get the information of sample composition as soon as possible, which is of great significance to evaluate the data quality of mineralized samples. OBJECTIVES To develop a method for determination of major elements in mineralized samples. METHODS The wavelength-energy dispersive X-ray fluorescence spectrometer was used to determine the major elements while adding more minor elements to the determination without prolonging the analysis time. The main elements were quantified by wavelength dispersion, while the minor elements were mainly determined by energy dispersion. Under the condition of ensuring the accuracy of the major elements, the measurement conditions were reasonably set and the energy spectrum measurement time was extended. RESULTS The method achieved the measurement of the major elements within 12 minutes using wavelength dispersion, and also provided results of 14 minor elements such as Rb, Sr, Y, Zr, Ba, Cu, Zn and the semi-quantitative results of 10 elements with narrow linear range or low content such as Co, Ge, Pr and Ta. The maximum limit of detection of 24 minor elements was 16.76μg/g. CONCLUSIONS Through the accuracy assessment, the determination results of major elements are consistent with the certified values, and the determination of minor elements with high content also meets the requirements of quantitative analysis. This method makes the analysts to get the information of sample composition quickly, provides a basis for more accurate and reliable data, and effectively solves the determination of major elements in complex mineralized samples.