Publications by authors named "Shihang Wang"

8 Publications

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Regional simulation of soil organic carbon dynamics for dry farmland in Northeast China using the CENTURY model.

PLoS One 2021 19;16(1):e0245040. Epub 2021 Jan 19.

School of Information Engineering, Jiangsu Vocational College of Agriculture and Forestry, Jurong, China.

Soil organic carbon content has a significant impact on soil fertility and grain yield, making it an important factor affecting agricultural production and food security. Dry farmland, the main type of cropland in China, has a lower soil organic carbon content than that of paddy soil, and it may have a significant carbon sequestration potential. Therefore, in this study we applied the CENTURY model to explore the temporal and spatial changes of soil organic carbon (SOC) in Jilin Province from 1985 to 2015. Dry farmland soil polygons were extracted from soil and land use layers (at the 1:1,000,000 scale). Spatial overlay analysis was also used to extract 1282 soil polygons from dry farmland. Modelled results for SOC dynamics in the dry farmland, in conjunction with those from the Yushu field-validation site, indicated a good level of performance. From 1985 to 2015, soil organic carbon density (SOCD) of dry farmland decreased from 34.36 Mg C ha-1 to 33.50 Mg C ha-1 in general, having a rate of deterioration of 0.03 Mg C ha-1 per year. Also, SOC loss was 4.89 Tg from dry farmland soils in the province, with a deterioration rate of 0.16 Tg C per year. 35.96% of the dry farmland its SOCD increased but 64.04% of the area released carbon. Moreover, SOC dynamics recorded significant differences between different soil groups. The method of coupling the CENTURY model with a detailed soil database can simulate temporal and spatial variations of SOC at a regional scale, and it can be used as a precise simulation method for dry farmland SOC dynamics.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245040PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7815115PMC
January 2021

Effect of Air Gap on Electrical Tree in Epoxy Resin Under High Frequency Bipolar Square-Wave Voltage.

Materials (Basel) 2020 Dec 15;13(24). Epub 2020 Dec 15.

State Key Laboratory of Power Grid Environmental Protection, China Electric Power Research Institute, Wuhan 430074, China.

Insulation fails quickly under high-frequency AC high voltage, especially bipolar square-wave voltage with a high d/d. It is of great significance to study the failure mechanism of epoxy casting insulation under such kind of voltage. In this paper, pin-plane epoxy casting insulation samples with air gaps were prepared, and the relation between the electrical trees under the high frequency bipolar square-wave voltage and the air gap conditions and voltage frequencies (1~20 kHz) were studied. Results indicated that, with the presence of air gaps, the electrical trees were bush-type and had a relatively slow growth rate, which was different from the fast-growing branch-type trees in the samples without air gap. The electrical tree characteristics related with the size of air gap and voltage frequency were also studied. The electrical tree grew faster under higher voltage frequency or with a smaller air gap. Results proved that discharge introduced a lot of defects for the surface layer of the epoxy resin samples and hence induced the possibility of multi-directional expansion of electrical trees. In addition, the resulting heat accumulation and unique charge transport synergistically affected the electrical tree characteristics under the high frequency bipolar square-wave voltage.
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http://dx.doi.org/10.3390/ma13245722DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7765362PMC
December 2020

Influence of Oxygen Diffusion on Thermal Ageing of Cross-Linked Polyethylene Cable Insulation.

Materials (Basel) 2020 Apr 29;13(9). Epub 2020 Apr 29.

State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China.

Thermal ageing of cross-linked polyethylene (XLPE) cable insulation is an important issue threatening the safe operation of power cables. In this paper, thermal ageing of XLPE was carried out at 160 °C in air for 240 h. The influence of oxygen diffusion on thermal ageing of XLPE was investigated by Ultraviolet-visible spectrophotometer (UV-Vis), tensile testing, and Fourier transformed infrared spectroscopy (FTIR). It was observed that the degradation degree not only depended on ageing time but also on sample positions. The thermally aged samples were more oxidized in the surface region, presented a darker color, more carbon atoms appeared in the conjugate cluster, had smaller elongation at break and tensile strength, and a larger carbonyl index. As ageing time increased, the non-uniform oxidation of the XLPE samples became more prominent. The degree of non-uniform oxidation caused by oxygen diffusion was quantitatively studied by first order oxidation kinetic. The calculated results demonstrated that carbonyl index measured by FTIR was more sensitive to non-uniform oxidation with a shape parameter in the range of 1-2. The result shown in this paper is helpful for interpreting and predicting the non-uniform ageing behavior of high voltage XLPE cables.
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http://dx.doi.org/10.3390/ma13092056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7254229PMC
April 2020

Effects of Functionalized Nano-TiO on the Molecular Motion in Epoxy Resin-Based Nanocomposites.

Materials (Basel) 2020 Jan 1;13(1). Epub 2020 Jan 1.

State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China.

Epoxy resin-based nanocomposites have been widely researched for being potential insulating materials in high voltage power equipment. In this paper, nano-TiO particles were chosen and surface-modified by a silane coupling agent containing an epoxy group. The effect of functionalized nano-TiO doping on the physical properties of epoxy resin was studied. The results of differential scanning calorimetry show that increased significantly and can be increased by up to 35 °C. Therefore, it is believed that the suppression of molecular motion by the addition of nanofillers works effectively in the case of this functionalized nano-TiO and a strong interaction between the epoxy resin and the nano-TiO was formed after surface modification. Consequently, dynamic mechanical properties, thermal conductivity, electrical conductivity, and trap characteristics of epoxy resin are all adjusted after introducing functionalized nano-TiO. All of these physical properties were analyzed from the perspective of suppression of molecular motion, and it is of significance to establish the theory of a nanocomposite dielectric. Besides, the results show that the epoxy/TiO nanocomposite is expected to be applied in the insulation system of electrical equipment.
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http://dx.doi.org/10.3390/ma13010163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981935PMC
January 2020

Machine Learning Methods to Predict Social Media Disaster Rumor Refuters.

Int J Environ Res Public Health 2019 04 24;16(8). Epub 2019 Apr 24.

Business School, Sichuan University, Chengdu 610064, China.

This research provides a general methodology for distinguishing disaster-related anti-rumor spreaders from a non-ignorant population base, with strong connections in their social circle. Several important influencing factors are examined and illustrated. User information from the most recent posted microblog content of 3793 Sina Weibo users was collected. Natural language processing (NLP) was used for the sentiment and short text similarity analyses, and four machine learning techniques, i.e., logistic regression (LR), support vector machines (SVM), random forest (RF), and extreme gradient boosting (XGBoost) were compared on different rumor refuting microblogs; after which a valid and robust distinguishing XGBoost model was trained and validated to predict who would retweet disaster-related rumor refuting microblogs. Compared with traditional prediction variables that only access user information, the similarity and sentiment analyses of the most recent user microblog contents were found to significantly improve prediction precision and robustness. The number of user microblogs also proved to be a valuable reference for all samples during the prediction process. This prediction methodology could be possibly more useful for WeChat or Facebook as these have relatively stable closed-loop communication channels, which means that rumors are more likely to be refuted by acquaintances. Therefore, the methodology is going to be further optimized and validated on WeChat-like channels in the future. The novel rumor refuting approach presented in this research harnessed NLP for the user microblog content analysis and then used the analysis results of NLP as additional prediction variables to identify the anti-rumor spreaders. Therefore, compared to previous studies, this study presents a new and effective decision support for rumor countermeasures.
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http://dx.doi.org/10.3390/ijerph16081452DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6518238PMC
April 2019

Effects of matrix metalloproteinase inhibitor doxycycline and CD147 antagonist peptide-9 on gallbladder carcinoma cell lines.

Tumour Biol 2017 Oct;39(10):1010428317718192

Department of General Surgery, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China.

Gallbladder carcinoma is the most common and aggressive malignancy of the biliary tree and highly expresses CD147, which is closely related to disease prognosis in a variety of human cancers. Doxycycline exhibited anti-tumor properties in many cancer cells. CD147 antagonist peptide-9 is a polypeptide and can specifically bind to CD147. The effect of these two drugs on gallbladder cancer cells has not been studied. The aim of this study is to investigate the effect of doxycycline and antagonist peptide-9 on gallbladder carcinoma cells and the possible mechanism of inhibition on cancer cell of doxycycline. To investigate the effects of doxycycline and antagonist peptide-9 on gallbladder carcinoma cells (GBC-SD and SGC-996), cell proliferation, CD147 expression, and early-stage apoptosis rate were measured after treated with doxycycline. Matrix metalloproteinase-2 and matrix metalloproteinase-9 activities were measured after treated with different concentrations of doxycycline, antagonist peptide-9, and their combination. The results demonstrated that doxycycline inhibited cell proliferation, reduced CD147 expression level, and induced an early-stage apoptosis response in GBC-SD and SGC-996 cells. The matrix metalloproteinase-2 and matrix metalloproteinase-9 activities were inhibited by antagonist peptide-9 and doxycycline, and the inhibitory effects were enhanced by combined drugs in gallbladder carcinoma cell lines. Taken together, doxycycline showed inhibitory effects on gallbladder carcinoma cell lines and reduced the expression of CD147, and this may be the mechanism by which doxycycline inhibits cancer cells. This study provides new information and tries to implement the design of adjuvant therapy method for gallbladder carcinoma.
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http://dx.doi.org/10.1177/1010428317718192DOI Listing
October 2017

Fast Photoinduced Large Deformation of Colloidal Spheres from a Novel 4-arm Azobenzene Compound.

ACS Appl Mater Interfaces 2015 Aug 24;7(30):16889-95. Epub 2015 Jul 24.

Department of Chemical Engineering, Key Laboratory of Advanced Materials (MOE), Tsinghua University, Beijing 100084, People's Republic of China.

A novel 4-arm shaped amphiphilic azobenzene compound was synthesized. The tetraphenylethylene (TPE) core precursor was prepared and further modified by azo coupling reaction at the four peripheral groups. Colloidal spheres could be directly prepared by self-assembly of the prepared amphiphilic azobenzene compound in selective solvents (THF/H2O), which were characterized by using transmission electron microscopy. The colloid diameters could be controlled by adjusting the initial compound concentration and water-adding rate in the preparation processes. By irradiation with visible linearly polarized LED light (450 nm), fast photoinduced deformation of the colloidal spheres along the polarization direction was observed. A very large deformation degree (l/d > 4) could be easily obtained.
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http://dx.doi.org/10.1021/acsami.5b05651DOI Listing
August 2015

Novel biodegradable drug-eluting stent composed of poly-L-lactic acid and amorphous calcium phosphate nanoparticles demonstrates improved structural and functional performance for coronary artery disease.

J Biomed Nanotechnol 2014 Jul;10(7):1194-204

Bioabsorbable drug-eluting stents (BDES) offer multiple advantages over a permanent bare metal stent (BMS) for coronary artery disease (CAD). However, current BDES remains two major issues: inferior radial strength and biocompatibility. PowerStent Absorb BDES, fabricated by co-formulating amorphous calcium phosphate (ACP) nanoparticles with poly-L-lactic acid (PLLA/ACP, 98/2, w/w) and 2% Paclitaxel (PAX, w/w) was designed to address these issues. Two cohorts of 6 miniature pigs were each implanted with PLLA/PAX (control, 2% PAX, w/w) or PowerStent Absorb BDES. After 1 month in-vivo study, histological analyses showed significantly reduced restenosis in the PowerStent Absorb BDES cohort relative to the control cohort (44.49 +/- 410.49% vs. 64.47 +/- 16.2%, p < 0.05). Stent recoil (21.57 +/- 5.36% vs. 33.81 +/- 11.49, P < 0.05) and inflammation (3.01 +/- 0.62 vs. 4.07 +/- 0.86, P < 0.01) were also obviously decreased. From in-vitro studies, PLLA/ACP/PAX stent tube maintained significantly greater radial strength than control group during 6 months in-vitro degradation (PLLA/ACP/PAX vs. PLLA/PAX: before hydrolysis: 82.4 +/- 1.9 N vs.74.8 +/- 3.8 N; 6 weeks: 73.9 +/- 1.8 N vs. 68.0 +/- 5.3 N; 3 months: 73.5 +/- 3.4 N vs.67.2 +/- 3.8 N; 6 months: 56.3 +/- 8.1 N vs. 57.5 +/- 4.9 N). Moreover, ACP facilitated the hydrolytic degradation of PLLA compared with control one (62.6% vs. 49.8%), meanwhile, it also increased the crystallinity of PLLA (58.4% vs. 50.7%) at 6 months. From SEM observations, ACP created nanometer pores that enlarge gradually to a micrometer scale as degradation proceeds. The changes of the porosity may result in greatly promoting re-endothelialization.
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http://dx.doi.org/10.1166/jbn.2014.1868DOI Listing
July 2014