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Mechanism of Packing Rigidity Gain in Sand Aging: From the Perspective of Structural Order Evolution
Chengjun Liu,Pei Tai,Zhaofeng Li,Wenbiao Hu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.6
Rigidity gain can be observed in sand aging but is usually accompanied by minute densification.This phenomenon is inconsistent with the conventional diagram of rigidity/jamming transition for granules and therefore too enigmatic to be utilized in the field by engineers. Therefore, this study aims to reveal the mechanism of rigidity gain and reconcile the inconsistency in sand aging. The aging processes of two sand packings with the same mono-sized spheres but different initial densities were reproduced via discrete element method simulations. In the simulations, sudden increases in the solid fraction destroyed the similarity between the evolution processes of rigidity gain and densification, confirming the inadequacy of explaining this gain considering densification alone. The bond-orientational order remained almost unchanged, while the contact-force order generally increased over time with distinct drops, similar to the change in rigidity gain. This evolution pattern is attributed to the laws of thermodynamics, which require the Gibbs energy of the sand packing to decrease over time, and contact-force order reduction assists with this decrease. Simultaneously, this reduces the nonaffinity under shear and rigidity demolition, consequently dominating the rigidity gain mechanism in sand aging. Based on these findings, the conventional diagram of rigidity transition was modified to jointly consider the effects of the solid fraction and structural orders. The proposed diagram can depict how the sand packing rigidity is enhanced over time and can better guide the consideration of the sand aging effect in the field.
A Duplex PCR Assay for Rapid Detection of Phytophthora nicotianae and Thielaviopsis basicola
Liu, Na,Jiang, Shijun,Feng, Songli,Shang, Wenyan,Xing, Guozhen,Qiu, Rui,Li, Chengjun,Li, Shujun,Zheng, Wenming The Korean Society of Plant Pathology 2019 Plant Pathology Journal Vol.35 No.2
A duplex PCR method was developed for simultaneous detection and identification of tobacco root rot pathogens Phytophthora nicotianae and Thielaviopsis basicola. The specific primers for P. nicotianae were developed based on its internal transcribed spacer (ITS) regions of ribosomal gene, ras gene and hgd gene, while the specific primers for T. basicola were designed based on its ITS regions and ${\beta}$-tubulin gene. The specificity of the primers was determined using isolates of P. nicotianae, T. basicola and control samples. The results showed that the target pathogens could be detected from diseased tobacco plants by a combination of the specific primers. The sensitivity limitation was $100fg/{\mu}l$ of pure genomic DNA of the pathogens. This new assay can be applied to screen out target pathogens rapidly and reliably in one PCR and will be an important tool for the identification and precise early prediction of these two destructive diseases of tobacco.
Haifeng Liu,Zhu Wang,Chengjun Sun 한국섬유공학회 2018 Fibers and polymers Vol.19 No.3
A facile and inexpensive way to prepare self-crosslinkable poly(dimethylsiloxane) (PDMS) for superhydrophobic treatment of cotton fabrics is reported in the study. Through thiol-ene click reaction between mercaptopropyltrimethoxysilane (MPTMOS) and vinyl-containing poly(dimethylsiloxane) (VPDMS), PDMS-g-TMOS can be simply and quickly synthesized. The trimethoxysilane group of PDMS-g-TMOS can react with hydroxyl group on cotton fabric and other -Si(OCH3)3 groups. The synthesized polysiloxane (PDMS-g-TMOS) was identified by FT-IR and 1H-NMR. The morphology of the treated cotton fabric was observed by SEM and XPS was used to analyze the elemental composition on the surface of cotton fabric. The analysis results indicated that the surface was fully covered with PDMS. Due to the low surface energy of PDMS and the rough surfaces of cotton fabric, the optimized water contact angle (WCA) and sliding angle were respectively 154 o±0.4 o and 14 o±0.5 o, indicating superhydrophobicity. Moreover, water spray test (AATCC Test Method 22-2010) was also applied to evaluate the water repellency of treated cotton fabric and a score of 90 was assigned according to AATCC Test Method 22- 2010. The durability of treated cotton fabric was tested by 50 laundering cycles. The resultant WCA barely decreased and the score of water spray test dropped from 90 to 80, showing the reasonable wash durability.
A Duplex PCR Assay for Rapid Detection of Phytophthora nicotianae and Thielaviopsis basicola
Na Liu,Shijun Jiang,Songli Feng,Wenyan Shang,Guozhen Xing,Rui Qiu,Chengjun Li,Shujun Li,Wenming Zheng 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.2
A duplex PCR method was developed for simultaneous detection and identification of tobacco root rot pathogens Phytophthora nicotianae and Thielaviopsis basicola. The specific primers for P. nicotianae were developed based on its internal transcribed spacer (ITS) regions of ribosomal gene, ras gene and hgd gene, while the specific primers for T. basicola were designed based on its ITS regions and β-tubulin gene. The specificity of the primers was determined using isolates of P. nicotianae, T. basicola and control samples. The results showed that the target pathogens could be detected from diseased tobacco plants by a combination of the specific primers. The sensitivity limitation was 100 fg/μl of pure genomic DNA of the pathogens. This new assay can be applied to screen out target pathogens rapidly and reliably in one PCR and will be an important tool for the identification and precise early prediction of these two destructive diseases of tobacco.
A Novel Double Layer Cantilevers Harvester for Vibration Energy
Chen Xiaojie,Qiu Chengjun,Qu Wei,Liu Yibo,Xia Hongyang 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.8
This paper reported a double layer cantilever harvester powered for vibration energy. A space layer between the PZT beam and the support silicon beam is existed, leading to the double layer cantilever structure. Such structure can allow the more strain generated by the piezoelectric layer due to the existing of space layer, and the output voltage is further increased. The formula of output voltage is then derived from the piezoelectric effect equation and vibration model. And the formula verifies the relationship of voltage and structure parameter. And the simulation in micrometer lever is used to discuss the relationship. Finally, the prototype is assembled and measured to verify the feature of the device. Experimentally, the 3.8V output voltage and 16.9uW output power is acquired.