Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
Consistency Assessment of Remote Sensing Dataset Based on Deep Learning
YAO Zhaoyuan, MA Lei, WAN Wei, SONG Benqin, WANG Weihong, DENG Jiwei, XIAO Lei, JI Rui, WEI Zhihao, CUI Yaokui
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (4): 563-568.   DOI: 10.13209/j.0479-8023.2022.116
Abstract252)   HTML    PDF(pc) (8176KB)(89)       Save
The current deep learning studies on remote sensing mainly focused on deep learning algorithms rather than deep learning datasets. This study proposes a method of dataset consistency assessment based on deep learning, in which the similarity among various types of ships from different sources (such as satellite remote sensing, 3D modeling, and web crawler) is evaluated and then used to characterize the consistency of the ship dataset. The results show that when the consistency of the dataset is the highest, the consistency by the proposed method is 1. When the consistency of the datasets is gradient, the consistency also changes. Images with similar data sources can be considered as same class, and images with greatly differences cannot be merged. Thus, the proposed method can assess the dataset consistency properly, and provide a suggestion to build an image dataset for deep learning training. 
Related Articles | Metrics | Comments0
Spatial Pattern and Driving Factors of Soil Microbial Biomass Carbon in Grassland in Northern Agro-Pastoral Transition Zone
CHEN Xinyue, YAO Xiaodong, ZENG Wenjing, WANG Wei
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (2): 250-260.   DOI: 10.13209/j.0479-8023.2021.003
Abstract657)   HTML    PDF(pc) (1079KB)(217)       Save
 In order to explore spatial pattern of soil microbial biomass carbon (MBC) and its environmental driving forces in grassland surface layer (0?10 cm) and subsurface layer (10?20 cm) in the agro-pastoral transition zone in northern China, 456 soil samples (57 sample sites, two soil layers and four replicates) were selected for investigation from Inner Mongolia-Liaoning plain, Bashang on the north of Beijing, the northern foot of Yinshan Mountain and Ningxia-Shaanxi Loess Plateau. The results showed that the spatial pattern of MBC was consistent between the surface and subsurface layer, which increased with latitude and had no significant change with longitude and elevation. With the increase of degradation degree, the reduction of soil microbial biomass in the subsurface layer was smaller than that in the surface layer. The difference of soil pH between the two layers decreased with the degree of degradation. The difference in soil MBC between surface and subsurface soils was regulated by the change of soil pH. The smaller the difference in pH between the two soil layers, the smaller the difference in MBC. Climate, vegetation and soil factors could affect the spatial variation of MBC, and soil factors were the main driving forces for MBC at the regional scale. The main influencing factor of MBC was soil total carbon at surface layer, and soil total nitrogen at subsurface layer. In the context of climate change and the intensification of human activities, the results were useful for predicting the response of soil microorganisms at the regional scale and maintaining and restoring ecological functions of degraded grasslands.
Related Articles | Metrics | Comments0
A Synchronizing Method for Dense Seismic Array Based on Ambient Noise Correlation Function
TIAN Yuan, WANG Weitao, LI Li, YU Changqing, ZHANG Haiming
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (4): 638-648.   DOI: 10.13209/j.0479-8023.2020.043
Abstract988)   HTML    PDF(pc) (7218KB)(162)       Save
This paper develops a NCF-based array synchronizing and error-estimation method employing the daily time shift of NCFs between nearby stations to estimate the stability of the timing system of a short-term but densely deployed seismic array. The error related to the reference NCF, the temporal change of ambient noise field, the data error and the optimization method in inversion are all estimated and correspondingly corrected based on the characteristics of a dense seismic array. The proposed method could effectively calculate the daily clock shift of a seismic array and pick out the time period of stations with obvious clock error. As an example, among the 209 stations of Yanyuan Seismic Array, it is found that 17 stations have obvious clock error with time shift over 1 s. These clock errors might be caused by the hardware or software problems related to the data acquisition system.
Related Articles | Metrics | Comments0
Responses of Ecosystem Carbon Fluxes to Warming and Dominant Species Removal along Elevational Gradients in the Alpine Meadow on the Tibetan Plateau
WANG Ankuo, WANG Wei, ZENG Hui
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (2): 299-309.   DOI: 10.13209/j.0479-8023.2018.092
Abstract900)   HTML    PDF(pc) (1808KB)(194)       Save

Experiments were conducted to investigate the effects of warming and dominant plant species removal on net ecosystem CO2 exchange (NEE), ecosystem respiration (ER) and gross ecosystem production (GEP) along elevational gradients (3200 m and 4000 m) in the alpine meadow on the Tibetan Plateau. The results showed that GEP was higher than ER at both elevations, indicating that both ecosystems were a net C sink during the growing season in 2017. At a lower elevation (3200 m), warming did not have a significant effect on ecosystem C flux due to water limitation caused by warming. At a wetter high elevation (4000 m), warming significantly stimulated ecosystem C fluxes, on average, the warming-induced increase in GEP (2.30 mg CO2/(m2·s)) was higher than that in ER (0.62 mg CO2/(m2·s)), leading to an increase in NEE. Dominant plant species removal did not have a significant effect on ecosystem C flux at either elevations, probably due to the compensatory effects of the remaining species, because the removal on above ground biomass (AGB) or below ground biomass (BGB) was not significant at both elevations. There was no significant interaction between warming and dominant species removal on the ecosystem C fluxes at either elevations. The results reveal the importance of soil moisture in mediating the response of ecosystem C flux to climate warming in alpine meadow ecosystems, and removal of a single dominant plant species may not have a significant impact on ecosystem C flux in species-rich regions.

Related Articles | Metrics | Comments0
Spatiotemporal Dynamics of Soil Extracellular Enzyme Activity and Its Influence on Potential Mineralization Rate of Soil Organic Carbon in Forests of Daxing’an Mountain Range
ZUO Yiping, ZHANG Xinyue, ZENG Hui, WANG Wei
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (6): 1311-1324.   DOI: 10.13209/j.0479-8023.2018.089
Abstract784)   HTML    PDF(pc) (2069KB)(218)       Save

In order to explore spatiotemporal dynamics of soil extracellular enzyme activity (EEA) and its influence on potential mineralization rate of soil organic carbon (SOC) of the Daxing’an Mountain range, soil samples of three forests (Pinus sylvestris forest; Birch forest; Larch pine forest) and three ground cover plants in Larch forest (Grass; Ledum; Moss) were collected from Daxing’an Mountain range in summer and winter. Activities of six enzymes including carbon- (C) (β-1,4-glucosidase, β-1,4-xylosidase, β-D-cellobiohydrolase), nitrogen- (N) (N-acetyl-β-glucosaminidase, leucine aminopeptidase) and phosphorus- (P) (acid phosphatase) acquisition, potential mineralization rate of SOC and main environmental factors were analyzed and potential driving mechanisms were explored. Results showed that Both Pinus sylvestris forest and Birch forest exhibited significant higher activities of enzyme C, N and P in summer, however, Larch forest showed contrary seasonal dynamic with soil EEA of moss soil significantly higher in winter. From summer to winter, soils of three forests and three ground cover plants all experienced reduced P vs. N limitation. Besides, soils of Pinus sylvestris forest and Birch forest both experienced increased C vs. nutrient limitation, however, Larch forest showed contrary seasonal dynamics with the existence of moss. In Pinus sylvestris forest and Larch forest, potential mineralization rate of SOC exhibited higher in winter while Birch forest showed contrary trend. Analysis showed that potential mineralization rate of SOC was influenced by enzyme C and enzyme N significantly, whereas little influenced by enzyme P. C vs. nutrient limitation had little correlation while P vs. N limitation had significant negative correlation with potential carbon mineralization rate.

Related Articles | Metrics | Comments0
Fine Root Productivity and Turnover Rate Respond Nonlinearly to Increased Nitrogen Availability
ZHANG Jiangyong, WANG Wei, ZENG Hui
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (4): 828-838.   DOI: 10.13209/j.0479-8023.2018.002
Abstract532)   HTML    PDF(pc) (827KB)(188)       Save

A N addition experiment was established with four treatments: control (no fertilization), low-N (20 kgN/(hm2·a)), medium-N (50 kgN/(hm2·a)) and high-N fertilization (100 kgN/(hm2·a)) in an N-limited Pinus sylvestris forest in Hebei Province, North China to study the production, biomass and turnover of fine root systematically. The results showed that fine root productivity (NPPfr) increased in low-N plots, decreased in high-N treatment, while the proportion of NPPfr to net primary productivity (NPP) reduced in low-N addition and increased in medium-N addition. With the increase of N availability, root biomass decreased, turnover rate increased, and carbon returned to soil decreased at first and increased later. The influence of N availability on NPPfr didn’t change with depth, while turnover rate varied among depth. N-addition made an impact on fine root productivity through soil nitrogen content, soil carbon content and soil pH, while affecting turnover rate of fine root by root carbon and nitrogen content.

Related Articles | Metrics | Comments0
A Study of Articulatory Features Based Detection of Mandrain Pronunciation Erroneous Tendency for Automatic Annotation
WEI Xing, WANG Wei, CHEN Jingping, XIE Yanlu, ZHANG Jinsong
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 243-248.   DOI: 10.13209/j.0479-8023.2017.152
Abstract835)   HTML3)    PDF(pc) (1670KB)(408)       Save

For the purpose of relieving the time cost and inconformity in annotation, the authors use an articulatory features based mispronunciation detection system to give an Top-N feedback and use this feedback to assist manual annotation. As a result, the consistency rate of phoneme labels in proposed system increases from 80.7% to 92.48%. In addition, the time cost for annotating each sentence reduce from 10 to 3 minutes. The results indicate that proposed automatic annotation system is practical, and there is also a room for further improvement.

Related Articles | Metrics | Comments0
Formation Ages, Petrogenesis and Geological Implications of the Archean Granitoid Rocks in the Xinbin-Weiziyu Area, Northern Liaoning Province
WANG Kang, LIU Shuwen, WANG Maojiang, WANG Wei, YAN Ming
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (1): 61-79.   DOI: 10.13209/j.0479-8023.2017.067
Abstract771)   HTML12)    PDF(pc) (53921KB)(225)       Save

The granitoid rocks in the Xinbin-Weiziyu area, northern Liaoning Province, comprise tonalitictrondhjemitic gneisses and monzogranite-syenogranite plutons. To determine their formation ages and petrogenesis, zircon U-Pb-Hf isotopic analyses and whole-rock geochemical analyses are conducted on these granitoid rocks. LAICP-MS zircon U-Pb isotopic dating data reveal that the tonalitic and trondhjemitic gneisses emplaced at 2588±4 Ma (MSWD=1.3) and 2587±6 Ma (MSWD=1.8), respectively, and the monzogranite-syenogranite intrusions formed at 2555±4 Ma (MSWD=0.51). Whole-rock geochemistry and zircon Lu-Hf isotopes suggest that magmatic precursors of the tonalitic-trondhjemitic gneisses were derived from partial melting of subducted slabs and the magmas were contaminated by the mantle wedge materials during their ascent. Some of the monzogranitesyenogranite plutons were produced by partial melting of metagreywackes, whereas the others were generated by partial melting of a mixed source composed of metabasalts and metasedimentary rocks. Integrated with recent studies, the Neoarchean granitoid rocks in the Xinbin-Weiziyu area may have been generated under an active continental margin.

Related Articles | Metrics | Comments0
Geometry and Tectonic Evolution of the Laojunmiao Break-Thrust Belt in the Northern Margin of Qilian Mountain
XIAO Yuxiang, DU Wenbo, ZHANG Bo, ZHANG Jinjiang, HOU Xiulin, WANG Wei, HE Xin, LI Xiaojun, YIN Congyuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 891-901.   DOI: 10.13209/j.0479-8023.2016.054
Abstract1583)   HTML    PDF(pc) (6159KB)(1466)       Save

On the base of the 3D seismic profile interpretations, combined with the previous findings, geometry and tectonic evolution across and along the Laojunmiao break-thrust belt in the northern margin of the Northern Qilian belt are deciphered. The Laojunmiao belt is a bi-layer thrust system, consisting of a trishear faultpropagation fold system in the upper part, wedge-shaped thrust in the lower part. The Laojunmiao thrust system is linked with the NE-SW striking-slip 134 fault in the western segment, which forms a unified system of fracture on the Laojunmiao belt. Thrusting sheet above the hanging wall of the 134-Laojunmiao fault system is folded under nearly E-S compressive stress field, which results in the N-S striking folding to superpose on the Cenozoic bedding.

Related Articles | Metrics | Comments0
Research on the Construction of Bilingual Movie Knowledge Graph
WANG Weiwei, WANG Zhigang, PAN Liangming, LIU Yang, ZHANG Jiangtao
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (1): 25-34.   DOI: 10.13209/j.0479-8023.2016.022
Abstract1267)   HTML    PDF(pc) (658KB)(934)       Save

This paper proposes a method to construct Bilingual Movie Knowledge Graph (BMKG). The authors first builds Bilingual Movie Ontology (BMO) through a semi-automatic way, and aligns each data source with it in order to ensure semantic consistency of heterogeneous data sources. For entity linking, the proposed method makes best use of the field characteristics and calculate entity similarity based on both Word2Vec and TFIDF models, which greatly improve entity linking. For entity matching, a similarity flooding based algorithm is proposed, which utilizes the intrinsic links between the movie data sources, addressing the problem of similarity computation between cross-lingual entities. The experiment results show that the entity matching precision is over 90% when the threshold is above 0.75. In addition, a movie knowledge graph sharing platform is also built to provide open data access and query interface.

Related Articles | Metrics | Comments0
Temporal and Spatial Variation of Ecological Risk Analysis in Yunnan Province Based on Land Use Spatial Structure
WANG Weiqi,LI Tianhong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract652)      PDF(pc) (1028KB)(469)       Save
With the support of GIS and statistical analysis method, six landscape metrics reflecting the land use spatial structure were selected to build and calculate the ecological risk of Yunnan Province and its 16 prefectures using land use/cover maps of 100 m×100 m grid in 1980s, 1990, 2000 and 2005. The spatial and temporal variations of ecological risk was mapped and analyzed. Results showed that 1) The ecological risk of Yunnan Province was in the medium level with high risk in the northeast and southwest and low risk in the northwest and southeast from the view of spatial distribution; during the study periods, Diqing, Nujiang, Lijiang, Dali, Kunming, Yuxi, and Wenshan were all at a low risk level, while Lincang, Zhaotong and Qujing were in high risk areas. 2) The distribution of each prefecture’s ecological risk did not change obviously in 2005, compared with that in the 1980s. Most prefectures’ ecological risk level stayed the same level. 3) The ecological risk of each prefecture presented a trend of increasing in 1980s?1990 and 1990?2000. However, most prefectures experienced risk decrease in 2000?2005. 4) From 1980s to 2005, more than eighty percent of prefectures’ the ecological risk remained at their original level. The results can provide a scientific basis for ecological construction and regional ecological planning.
Related Articles | Metrics | Comments0
C-TERN: A Temporal Information Processing Algorithm of Chinese Military News Story Based on Cascade Finite State Automata
WANG Wei,ZHAO Dongyan,SU Tingting
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract574)      PDF(pc) (506KB)(280)       Save
The authors propose a new method C-TERN to recognize and normalize the temporal expression in military story based on cascade finite state automata. Firstly, C-TERN recognizes the temporal expression in military story, and layers the temporal information extracted from general language and military language, and recognizes the temporal by layer. Then, in the procedure of temporal expression normalization, C-TERN ratiocinates and normalizes the simple/specify time, duration time, absolute and relative temporal expression in four steps. The method pays special attention to the correctness of the regulation extraction, the dispelling of the collision between regulations, and the reasonability of the matching method. The experimental results on multi-information show that proposed method can recognize and normalize the absolute and relative temporal expression as well as the simple/specify time and duration time effectively. It can better meets the temporal information processing needs in military applications.
Related Articles | Metrics | Comments0
Research on the Characteristics of Wind Energy Resources over Huangang Wind Farm in Jiangsu Province
WANG Yefang,LI Chengcai,SHI Guangming,LI Jian,LI Wusheng,LI Shuyong,WANG Wei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract638)      PDF(pc) (776KB)(341)       Save
Based on the analysis of wind data measured at one wind measurement tower over Huangang Wind Farm in Jiangsu Province from Dec. 2010 to Nov. 2011, it was calculated that at 10, 50, 70 and 80 m heights the annual average wind speed was 4.0?6.1 m/s, the annual average wind power density was 80.4?238.4 W/m2, the annual effective wind power density was 116.5?262.5 W/m2, the annual effective hours were 5777?7845 h, and the annual effective wind energy density was 679.3?2041.5 (kW?h)/m2. In addition, the dominant wind directions were NNE, N and NE, the sum of them took up nearly 30% of the full year wind directions, the wind energy density of the dominant wind directions accounted for almost 50% of the full year wind energy density, and the wind speed was mainly ranging from 3 to 8 m/s, about 80% of the full year wind speeds. Overall, wind energy resource was abundant in this region. Especially the hub height of the already built wind turbines had the wind power density of more than 250 W/m2, and the effective hours took up nearly 90% of the full year. Therefore, wind energy resource had a great value of development and utilization in this region.
Related Articles | Metrics | Comments0
Encode Landslide and Rock Fall Hazard and Interpretation with Monte Carlo Model in China
WANG Wei,LI Tianhong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract630)      PDF(pc) (691KB)(300)       Save
The multi-scale encoding system for landslide and rock fall hazard and interpretation with Monte Carlo model is applied to hazard assessment in China. Counties and cities of China are encoded according to landslide and rock fall hazard information. Monte Carlo simulation is used to interpret some codes as reference, and the other codes are interpreted by matching them with reference. The whole China is zoned into five regions according to interpreted code hazard degrees that include very low, low, medium, high and very high. The correlation analysis shows that landslide and rock fall codes have high correlations with codes of geology factor and geomorphology factor. Verification of BP neural network, comparison between results interpreted by Monte Carlo model and historical disaster record and comparison between proposed approach and other approach indicate that results given by proposed approach are sufficient accuracy.
Related Articles | Metrics | Comments0
A Multi-scale Encoding System for Landslide and Rock Fall Hazard and Interpretation with Monte Carlo Model
WANG Wei,LI Tianhong,NI Jinren
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract588)      PDF(pc) (544KB)(339)       Save
An encoding system for landslide and rock fall hazard, applicable to multi-scale, is proposed. Multi-factor information that can affect the landslide and rock fall hazard occurrences and their hazard degrees is given to study units by codes at different scales. Some study units with historical disaster records are selected as reference, and codes of these units in reference are interpreted by Monte Carlo model. Then a large number of other units can be interpreted according to the assumption that regions with similar codes should have similar hazards. Wide range applications, paying more attention to uncertainty study, low requirements for data, intuitive and detailed information presented by codes, avoiding redundancy of data and simplifying calculation are advantages of this approach. This study has great significance for identification of landslide and rock fall hazard characteristics and hazard assessment and prevention.
Related Articles | Metrics | Comments0
Studies on Improving the PL Spectra of ZnO Nanowire
WANG Xiaowei,SUN Yanghui,WANG Wei,ZHU Rui,ZHU Xinli,HOU Yumin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Identification of Topic Sentence about Key Event in Chinese News
WANG Wei,ZHAO Dongyan,ZHAO Wei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1005)      PDF(pc) (571KB)(1427)       Save
The authors propose an approach to extract topic sentences that describe key event from a news article. Considering the special structure of news articles, the relations between news articles and key events reported in them is studied, as well as the characteristics of a news headline in three aspects: information, form and language. A novel method based on the information aspect of a headline is used to extract a topic sentence which contains the key event information from a news story. The method first classifies a news headline as informative or non-informative, and then considers text and semantic features of a sentence, such as word frequency, sentence length, location in the text and word co-concurrency with the headline, to evaluate the importance for each sentence and select the most important one as the topic sentence. Experiment results show that this method can identify a topic sentence accurately and the proposed approach makes a good preparation for event information extraction.
Related Articles | Metrics | Comments0
Emplaced and Metallogenetic Times of Tongchang Diorities, Southern Shaanxi Province and Its Geological Implications
WANG Wei,LIU Shuwen,WU Fenghui,LI Qiugen,WANG Zongqi,YANG Kai,YAN Quanren,WANG Ruiting,YANG Pengtao
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract653)            Save
Tongchang dioritic pluton in Southern Shaanxi Province is located in the tectonic domain of the Mianxian-Lueyang-Yangpingguan triangle block, northern margin of Yangzi Craton, and consists mainly of diorite, quartzdiorite and granodiorite. Zircon grains separated from these rocks are dated using LA-ICPMS and SHRIMP U-Pb isotopic methods. The dating results indicate three intrusive stages of the Tongchang dioritic pluton, and early diorite emplaced at 879±7 Ma; middle quartz diorite at 848±5 Ma to 840 ±7 Ma, with copper ore-bearing albitite emplced at 834±7 Ma, which is consistent with the crystallization age of quartz diorite within error range, and the last granodiorite at 824±5 Ma. These zircon U-Pb isotopic dating results reveal that the emplacements of the Tongchang diorites and related copper deposit did not occur in Paleozoic but in Jinning stage of Neoproterozoic era. The magmatic activity and related copper deposit mineralization are important responses to the breakup event of global Rodinia supercontinent( 860-750 Ma).
Related Articles | Metrics | Comments0
Characteristics of Eutrophication and Variation Trend of Nitrogen and Phosphorus Nutrient in Shenzhen Bay
SUN Jinshui,WAI Onyx Wing-Hong,WANG Wei,LEI Li,MAO Xiaoling
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract785)            Save
Based on the field data in 1986?2007 in Shenzhen bay, annual changes characteristics of nitrogen and phosphate concentrations, as well as their correlations with each other are presented. Furthermore, the Nutrition Quality Index (NQI) is employed to assess the eutrophication degree of Shenzhen bay. The dissolved inorganic nitrogen(DIN) concentration shows an increasing trend, while phosphate( PO3-4-P) concentrations decrease gradually. Ammonia nitrogen ( NH+4-N) is the primary form of inorganic nitrogen in Shenzhen bay indicating that inorganic nitrogen is in unstable thermodynamic equilibrium. The ratio of DIN/ P increased gradually before 1998, and decreased after 2002. The variation and components of nutrients could influence the community structure of phytoplankton, and the dominant red tide species have been transformed from diatom to dinoflagellate. Nutrient correlation is significant at the 0.01 level, which shows that the nutrient undergo similar biogeochemistry processes. The NQI shows that Shenzhen bay is in high eutrophic status, and it is urgent resort to effective plan for controlling water pollution in the inflow river.
Related Articles | Metrics | Comments0
Effects of Pubertal and Adult Social Isolation on the Latent Inhibition of Rats
JIN Jian,WANG Weiwen,MENG Qingxuan,LIU Mei,SHAO Feng
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract688)            Save
The present study investigated the effects of pubertal and adult social isolation on latent inhibition of rats and explored its dopamine substrate. In experiment 1, Wistar male rats were given 14 days isolated rearing during their puberty (PND38-51), then latent inhibition (LI) was tested in both adolescent and young adult rats, the results show that social isolation during peri-puberty impaired LI of young adult rats, but left LI of adolescent rats intact; In experiment 2, Wistar male rats were given 14 days isolated rearing during their puberty (PND58-71), then LI was tested at PND72 and PND86, the results show that social isolation during adult period did not affect LI of rats; In experiment 3, after the same isolation treatment like experiment 1, dopamine (DA) level in nucleus accumbens (NAc) was measured in adolescent and young adult rats, the results showed that social isolation during puberty increased the DA level of NAc in young adult rats, but not in adolescent rats. These results suggest that compared to social isolation during adult period, the expression of LI deficit induced by isolated rearing during puberty is found after a developmental delay, and DA in NAc may be involved in the neural substrate, which may mirror some aspects of the ontogency of schizophrenic symptoms.
Related Articles | Metrics | Comments0
The Wide-Band Scattering Characteristics Analysis of Satellite Targets in Different Space Attitude Conditions
ZENG Rui,ZHOU Lezhu,LI Mingzhi,WANG Wei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract664)            Save
Wide-band scattering characteristics of typical spin stabilized satellite and triaxial stabilized satellite are computed by using finite-difference time-domain (FDTD). Compacts of the attitudes on scattering properties are investigated. The scattering properties of typical satellite targets in frequency domain are compared with the scattering properties in time domain. The results show that the satellite scattering properties in frequency domain are propitious to get the large-scale attitude information and the properties in time domain are propitious to get the small-scale attitude information. In addition, the change of rolling attitude more easily arouses the variety of scattering characteristics of typical satellite target than pitch attitude change does. The conclusions are valuable to the attitude identification of satellite and the design of ground based wide-band radar.
Related Articles | Metrics | Comments0
Condition and Effect of Reactor for Removal of Pentachlorophenol Catalyzed by Immobilized HRP
YANG Guang ,ZHANG Jianbo,WANG Shanlin ,YANG Yuxiang ,ZONG Yueru,WANG Weijing
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract641)            Save
Based on the optimum condition for removal of pentachlorophenol in water by using HRP immobilized by Fesorption-gelatin embedding-cross linkage method as catalyzer, the reacting fitting and the removal efficiency were studied. The flow rate of PCP solution through the fitting was selected for better removal efficiency of Pentachlorophenol. The repetitive use of immobilized HRP for PCP removal, and the effect of secondary treatment of wastewater were also examined. The results indicate that the optimal flow rate of PCP solution for the removal efficiency of the reacting fitting is around 3mL/min and the PCP removal rate is quite stable. Repetitive use of immobilized HRP for PCP removal is stable. Once the PCP removal efficiency of primary treatment couldn't meet the drainage standard for PCP concentration, secondary treatment is also feasible. The PCP removal rate of secondary treatment can reach 92.7%, and the residual concentration of PCP can reach 0.98mg/L, which is under national first drainage standard (5mg/L) evidently.
Related Articles | Metrics | Comments0
Improving the Field Emission Properties of a Graphite Paste Film by Nitrogen Ion Bombardment
WANG Weiwei,SUN HuiYU,LigangZHANG,Gengmin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract807)            Save
The field emission properties of a graphite paste film were found to have been greatly improved by nitrogen ion bombardment. The bombardment transformed the graphite surface into an array of graphite cones with a ~108cm-2 tip density. XPS measurement showed that plenty of nitrogen had been injected into the graphite film and there existed a large number of sp2 bonds. Field emission test demonstrated that the distribution of the emission sites in the post, bombardment film was much more dense and uniform than that of the original one. The maximum current density of 1.65mA/cm2 was also achieved, which was much higher than that of the pre, treatment sample.
Related Articles | Metrics | Comments0
Preparation and Application of Horseradish Peroxidase Immobilized in Fe3O4-Asorption-Gelatin-Entrapping Method
WANG Shanlin,ZHANG Jianbo,WANG Weijing,YANG Yuxiang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract707)            Save
Fe3O4-asorption-gelatin-entrapping method for immobilization of horseradish peroxidase was established. Immobilization efficiency of this carrier was compared with that of sodium alginate, gelatin and open pore gelatin cube. It was found that higher efficiency could be achieved by Fe3O4-asorption-gelatin-entrapping method. The stabilities of different immobilized enzymes and free HRP were also compared, and the stability of immobilized HRP with Fe3O4-gelatin as carrier was considerably higher than the stabilities of other enzymes. Effects of concentration of glutaraldehyde and gelatin, crosslinking time, dosage of HRP and Fe3O4 on the activity of immobilized HRP were studied. The results of optimal conditions of immobilization were as follows: the optimal ratio of dosage of HRP and Fe3O4 was about 95 u HRP/g Fe3O4, the optimal ratio of Fe3O4 and gelatin was 1.0g Fe3O4/10mL 10%~20% gelatin, the optimal glutaraldehyde concentration was 0.5% and the optimal crosslinking time was 30min. On this condition, the activity of immobilized HRP was about 1.1u/g and the recovery of enzyme activity was around 15%. Repetitive use of immobilized HRP for the elimination of PCP was examined and stable efficiency of PCP degradation was achieved.
Related Articles | Metrics | Comments0
Integrated Process of Thermal Hydrolysis and Anaerobic Sequencing Batch Reactor for the Treatment of Sewage Sludge
WANG Zhijun,WANG Wei,ZHANG Xihui
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract655)            Save
In recent years, the combined technology of thermal hydrolysis and continuous-flow stirred tank reactor(TH-CSTR) for sewage sludge treatment have attracted more and more interest. In this paper, the effects of thermal hydrolysis pretreatment on the characteristics and digestibility of sewage sludge were investigated, anaerobic sequencing batch reactor(ASBR) instead of CSTR was used and then the integrated process of TH-ASBR was studied. The results showed that the thermal hydrolysis pretreatment can improve the digestibility and the optimum pretreatment conditions were 170℃ and 30min retention time. When thermo-hydrolyzed sludge pretreated under above condition was respectively digested in ASBR and CSTR (control), the organic removal efficiencies and methane production rates of ASBR were higher than those of CSTR with 20, 10, 7.5 and 5-d HRTs, respectively. The optimum HRT of ASBR was 10 days. The TCOD removal efficiency and methane production rate of TH-ASBR process were 2793% and 2514% more than those of TH-CSTR process with 10-d HRT, respectively.
Related Articles | Metrics | Comments0
Degradation of 2,4-Dichlorophenols Catalyzed by Laccase Immobilized on Chitosan
CHEN Hui,ZHANG Jianbo,WANG Weijing,YANG Yuxiang,ZONG Yueru
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract896)            Save
Research on the removal of 2,4-DCP in aqueous solution by laccase immobilized on chitosan were studied. Factors, such as pH value, temperature and adsorption on support that could influence the oxidation were discussed in detail compared with free laccase. The results indicated that the optimal pH for 2,4-DCP removal by immobilized laccase was around 5.5, lower than the free enzyme for pH 6.0. The optimum temperature of immobilized laccase was between 35℃ and 45℃, wider than the free enzyme. Adsorption of chlorophenol on support had a little effect on the degradation reaction and removal rates of chlorophenols, and the decrease of chlorophenols levels was resulted from catalyzeing for laccase. The continuous oxidation of 2,4-DCP, carried out in the static system of immobilized laccase, showed that the removal efficiency of immobilized laccase still remained over 60% after 6 cycles of operation. Thus the catalytic efficiency of laccase was greatly improved.
Related Articles | Metrics | Comments0
On the General Solution of Anisotropic Piezoelasticity
XU Sipeng,WANG Wei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract648)            Save
The general solution of anisotropic piezoelasticity is obtained constructively. Its completeness and nonuniqueness are also proved.
Related Articles | Metrics | Comments0
Preparation and Characteristics of Immobilized Laccase from Coriolus versicolor on Chitosan
CHEN Hui,ZHANG Jianbo,WANG Weijing,YANG Yuxiang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract633)            Save
Laccase has been immobilized on chitosan with glutaraldehyde as crosslinking agent. The effects on the activity of immobilized laccase, such as concentration of glutaraldehyde, crosslinking time, laccase dosage and reaction time were studied. The results showed the optimal conditions of immobilization: the optimal glutaraldehyde concentration was 5%, the optimal crosslinking time was 8h, the optimal laccase dosage was 20mg/g carrier, and the optimal reaction time was 6h. On this condition, the recovery of enzyme activity was 52.2%. The results indicated that the optimal pH for immobilized laccase was around 4.5, which is lower than the best pH 5.0 for free enzyme. Compared with the free enzyme, its stability and repetition were considerably improved.
Related Articles | Metrics | Comments0
Removal of Pentachlorophenol (PCP) by Immobilized Horseradish Peroxidase (HRP)
YE Peng,ZHANG Jianbo,CHEN Song,YANG Yuxiang,WANG Weijing,WANG Shanlin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract908)            Save
Researches on the removal of PCP by free HRP with the existence of H2O2 were conducted. PCP was measured by safranine-T spectrophotometric method (GB 9803-88). Results indicated that HRP could effectively oxidate PCP in aqueous solution. Factors, such as acidity, temperature, enzyme activity, and initial concentration of PCP and H2O2, which could influence the oxidation, were studied. Results showed that the optimum pH value for free enzyme was 5~6; relative higher temperature could accelerate the reaction greatly; removal rate increased with the increase of enzyme concentration, and removal rate could reach nearly 70% under the highest enzyme concentration (about 0.05u/mL) adopted in the experiment; removal rate increased slightly with the increase of initial concentration of PCP; the molar ratio of the reaction between PCP and H2O2 is about 1∶2. Based on above results, researches on the oxidation of PCP by immobilized HRP were conducted. Firstly, through chemical bonding method, free HRP was immobilized on polyacrylamide gel prepared by γ ray radiation method; then immobilized HRP was filled into a column, and PCP was successfully oxidated by immobilized HRP column. Finally, results were analyzed and compared with results using free HRP.
Related Articles | Metrics | Comments0