15 results on '"Shao-Xian Li"'
Search Results
2. Generation of a static plasma electron grating
- Author
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Shao Xian Li, Junzhi Wang, Donald P. Umstadter, Vojtěch Horný, Dominika Mašlárová, and Qiang Chen
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Materials science ,business.industry ,Plane wave ,Physics::Optics ,Electron ,Plasma ,Grating ,Laser ,law.invention ,Standing wave ,Optics ,Physics::Plasma Physics ,law ,Physics::Atomic Physics ,business ,Inertial confinement fusion ,Photonic crystal - Abstract
A grid of equidistant electron stripes is generated during the collision of two laser pulses under a small angle in underdense plasma. Due to the oblique incidence, transverse standing wave in plasma is observed, in addition to the longitudinal traveling wave of the compound laser field. This standing wave results in the generation of plasma density grating. The ratio of the peak stripe density to background density can reach the value of 20:1. The grating period is determined by the interaction angle. Analytical theory of the compound electric fields is provided for plane waves. The grating formation is then verified via particle-in-cell simulations for short Gaussian laser pulses with typical experimental parameters. In addition, the interference pattern was also observed during experiments with Diocles laser. The results presented here are relevant for many laser-plasma applications, such as Raman scattering, inertial confinement fusion, plasma photonic crystals and laser wakefield acceleration.
- Published
- 2021
3. The effect of flame retardant-modified sepiolite nanofibers on thermal degradation and fire retardancy of low-density polyethylene
- Author
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Zhou Cheng, Wenbin Yang, Xiaoping Hu, Shao-xian Li, Wenxiong Li, and Yong Yao
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Thermogravimetric analysis ,Materials science ,Sepiolite ,Polyethylene ,Condensed Matter Physics ,Limiting oxygen index ,Thermogravimetry ,chemistry.chemical_compound ,Low-density polyethylene ,chemistry ,Thermal stability ,Physical and Theoretical Chemistry ,Composite material ,Fire retardant - Abstract
Flame retardant-modified sepiolite nanofiber (PSPHD-SEP) was fabricated through chemical grafting by introducing intumescent flame retardant oligomer (PSPHD) onto the surface of sepiolite fiber. Various sepiolite/low-density polyethylene (SEP/LDPE) composites have been prepared successfully via melt blending. The dispersion of various SEPs in LDPE matrix was observed by scanning electron microscope and transmission electron microscope. The thermal degradation behaviors of various SEP/LDPE composites with 3 mass% acid-modified sepiolite fiber (a-SEP) or PSPHD-SEP have been investigated employing thermogravimetric analysis/derivative thermogravimetry. The thermal degradation kinetics of neat LDPE, a-SEP/LDPE and PSPHD-SEP/LDPE systems was comparatively analyzed by means of Friedman and Flynn–Wall–Ozawa methods to further comprehend the effect of a-SEP and PSPHD-SEP on the thermal stability of LDPE. Due to the addition of PSPHD-SEP, the limiting oxygen index value of PSPHD-SEP/LDPE composite can reach 21.3%, and the UL-94V-2 rating is obtained. The cone calorimetry (CONE) tests showed that a reduced peak heat release rate can be achieved for PSPHD-SEP/LDPE composite accompanying with gas-phase fire retardant action.
- Published
- 2019
4. Wear and corrosion resistant coatings on surface of cast A356 aluminum alloy by plasma electrolytic oxidation in moderately concentrated aluminate electrolytes
- Author
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Li Cao, Huanjun Xie, Jinhui Cao, Yingliang Cheng, and Shao-xian Li
- Subjects
Materials science ,Sodium aluminate ,Aluminate ,Metallurgy ,Alloy ,Metals and Alloys ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,Plasma electrolytic oxidation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Geotechnical Engineering and Engineering Geology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Corrosion ,chemistry.chemical_compound ,chemistry ,Coating ,Aluminium ,Tungsten carbide ,Materials Chemistry ,engineering ,0210 nano-technology - Abstract
Plasma electrolytic oxidation of a cast A356 aluminum alloy was carried out in aluminate electrolytes to develop wear and corrosion resistant coatings. Different concentrations of 2, 16 and 24 g/L NaAlO 2 solutions and a silicate electrolyte (for comparison) were employed for the investigation. Wear performance and corrosion resistance of the coatings were evaluated by WC (tungsten carbide) ball-on-flat dry sliding tests and electrochemical methods, respectively. The results show that the coating formed for a short duration of 480 s in 24 g/L NaAlO 2 solution generated the best protection. The coating sustained 30 N load for sliding time of 1800 s, showing very low wear rate of ∼4.5×10 −7 mm 3 /(N·m). A low corrosion current density of ∼8.81×10 −9 A/cm 2 was also recorded. Despite low α -Al 2 O 3 content of the coating, the compact and nearly single layer nature of the coating guaranteed the excellent performances.
- Published
- 2017
5. The birefringence and extinction coefficient of positive and negative liquid crystals in the terahertz range
- Author
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Shao Xian Li, Dan Luo, Qi Fu Liu, and Zhen Tian
- Subjects
Range (particle radiation) ,Birefringence ,Materials science ,Terahertz radiation ,business.industry ,Optical property ,02 engineering and technology ,General Chemistry ,Molar absorptivity ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,010309 optics ,Optics ,Liquid crystal ,Extinction (optical mineralogy) ,0103 physical sciences ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Spectroscopy - Abstract
Birefringence and extinction coefficients of positive nematic liquid crystal (NLC) MLC-2142 and negative NLC BHR28000-400 are measured by terahertz time-domain spectroscopy system (THz-TDS). Frequency ranging from 0.1 to 0.6 THz, the birefringence of positive NLC MLC-2142 increases with the increase of frequency, and keeps larger than 0.23, which exhibits application potential in tunable broadband LC THz device where a large birefringence is required. In contrast, the birefringence of BHR28000-400 decreases with the increased frequency, which shows a completely different optical property from the positive NLC. The extinction coefficient of the above two kinds of liquid crystals are also investigated.
- Published
- 2016
6. Structure, morphology, and properties of LDPE/sepiolite nanofiber nanocomposite
- Author
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Xiu-Li Wang, Xiaoping Hu, Jian-Bing Zeng, Peng-Ji Wang, Yu-Zhong Wang, Shao-xian Li, and Quan-tong Zhang
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Thermogravimetric analysis ,Nanocomposite ,Materials science ,Polymers and Plastics ,Scanning electron microscope ,02 engineering and technology ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Low-density polyethylene ,Ultimate tensile strength ,Fiber ,Composite material ,0210 nano-technology ,Tensile testing - Abstract
Sepiolite (SEP) nanofibers have been modified by grafting with poly(pentaerythritol diphosphonate dichloride-hexamethylendiamine) (PSPHD) and compounded with low density polyethylene (LDPE) to form a nanocomposite. The various modified SEPs were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared, transmission electron microscopy (TEM), and thermogravimetric analysis. The Fourier transform infrared and X-ray photoelectron spectroscopy tests show that covalent bonding exists between SEP fiber and modifiers. The nanoscale size and morphologies of SEP fiber and modified SEP nanofibers can be observed clearly by TEM. The thermogravimetric analysis results reveal that the multi-step thermal degradation process of SEP fiber is changed by grafting modification. The various LDPE/SEP nanocomposites were characterized by scanning electron micrograph, TEM, dynamic mechanical analysis, and tensile test. The results suggest that a good interfacial modification effect has been obtained between PSPHD-SEP and LDPE matrix. A particular improvement in tensile strength is reflected in tensile tests. Dynamic mechanical analysis shows that the storage moduli (E') of PSPHD-SEP/LDPE nanocomposites are much higher than that of neat LDPE and a-SEP/LDPE systems. Copyright © 2015 John Wiley & Sons, Ltd.
- Published
- 2015
7. Preparation and Combustion Properties of Sepiolite/LDPE Composites
- Author
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Xiaoping Hu, Yan Chang, Liang Jun Li, Hui Min Heng, Yu Yang Guo, and Shao Xian Li
- Subjects
Low-density polyethylene ,Materials science ,Sepiolite ,Cone calorimeter ,General Engineering ,Char ,Composite material ,Combustion ,Intumescent ,Fire retardant - Abstract
The intumescent flame retardant poly-pentaerythritol diphosphonate dichloride- hexamethylendiamine (PSPHD) grafting sepiolite (PSPHD-SEP) and LDPE/PSPHD-SEP/IFR composites have been prepared. Cone calorimeter technique was employed to characterize the combustion behavior of LDPE/PSPHD-SEP/IFR composites. The results show that the peak and average heat release rates decreased significantly when 5% PSPHD-SEP was added in LDPE. The PSPHD-SEP can promote the char layer to form earlier and be more compact and increase the char residue yield. The compact char residue layer can prohibit the transfer of gas and heat during the burning, showing the improvement of flame retardance.
- Published
- 2011
8. Modification of Surface Velocity Calculation Formula in Tunnel Blasting
- Author
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Chuan Li, Shao Xian Li, Hai Liang Wang, and Xian Bin Xue
- Subjects
Surface (mathematics) ,Engineering ,business.industry ,Line (geometry) ,General Engineering ,Range (statistics) ,Empirical formula ,Particle ,Vibration velocity ,Structural engineering ,business ,Surface velocity ,Rock blasting - Abstract
The blasting vibration in Qingdao Cross-harbor Tunnel Guide Line Project is monitored and analyzed. We discover that the surface particle vibration velocity in the range of 5metres around the working face reduces fast, and that does not conform to Sadaovsk formula. This inquiry adopts the hypothesis-fitting-testing method to modify Sadaovsk formula. The empirical formula of the ground vibration velocity caused by blasting in tunnel is obtained.
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- 2011
9. Research on Moisture Porosity Test of Explosive Lining Materials after Long-Term Water Immersion
- Author
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Hai Liang Wang, Li Zhen Meng, Shao Xian Li, and Zhuo Cui
- Subjects
Materials science ,Moisture ,Explosive material ,Water immersion ,General Engineering ,Composite material ,Mortar ,Porosity ,Curing (chemistry) - Abstract
This paper measures moisture porosity of explosive lining test pieces after long-term water immersion, so are the test pieces in standard curing condition and in equal curing condition. We have analyzed the measured moisture porosity data of three kinds of test pieces after long-term water immersion. The results indicate that the moisture porosity of explosive lining test pieces is higher than that in standard curing condition and in equal curing condition.
- Published
- 2011
10. Hollow Effect Induced by Vibration in Cross-Harbor Tunnel
- Author
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Hai Liang Wang, Ru Cang Bao, Zhi Shen Wang, and Shao Xian Li
- Subjects
Surface (mathematics) ,Vibration ,Engineering ,business.industry ,Blasting vibration ,General Engineering ,Front (oceanography) ,Vibration velocity ,Geotechnical engineering ,Mechanics ,business ,Flattening ,Rock blasting - Abstract
The article was based upon analysis of the front-and-back surface vibration velocity of the working surface by monitoring the blasting operation at hidden digging section of Jiaozhou Bay cross-harbour tunnel in Tuandao road exit ramp. Research shows that the maxim-um value of the surface blasting vibration velocity appears on the front and back of the ground ,raging from 2 m to 7 m ,just above the working surface instead of the ground just above of the working surface. However, the surface vibration velocity generates behind the working surface was 1.2 to 1.4 times greater than the one generates at the front of the working surface. The front-and-back surface vibration velocity tends to be flattening on the ground which was more than 20 m away from the working surface, just above it.
- Published
- 2011
11. Genome plasticity and ori-ter rebalancing in Salmonella typhi
- Author
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Shao-Xian Li, Gui-Rong Liu, Wei-Qiao Liu, Shu-Lin Liu, Randal N. Johnston, and Kenneth E. Sanderson
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Genetics ,Gene Rearrangement ,Salmonella ,Genome evolution ,Virulence Factors ,Replication Origin ,Bacterial genome size ,Biology ,Salmonella typhi ,medicine.disease_cause ,Genome ,Pathogenicity island ,Evolution, Molecular ,chemistry.chemical_compound ,chemistry ,Gene density ,medicine ,Molecular Biology ,Ecology, Evolution, Behavior and Systematics ,DNA ,Genome, Bacterial - Abstract
Genome plasticity resulting from frequent rearrangement of the bacterial genome is a fascinating but poorly understood phenomenon. First reported in Salmonella typhi, it has been observed only in a small number of Salmonella serovars, although the over 2,500 known Salmonella serovars are all very closely related. To gain insights into this phenomenon and elucidate its roles in bacterial evolution, especially those involved in the formation of particular pathogens, we systematically analyzed the genomes of 127 wild-type S. typhi strains isolated from many places of the world and compared them with the two sequenced strains, Ty2 and CT18, attempting to find possible associations between genome rearrangement and other significant genomic features. Like other host-adapted Salmonella serovars, S. typhi contained large genome insertions, including the 134 kb Salmonella pathogenicity island, SPI7. Our analyses showed that SPI7 disrupted the physical balance of the bacterial genome between the replication origin (ori) and terminus (ter) when this DNA segment was inserted into the genome, and rearrangement in individual strains further changed the genome balance status, with a general tendency toward a better balanced genome structure. In a given S. typhi strain, genome diversification occurred and resulted in different structures among cells in the culture. Under a stressed condition, bacterial cells with better balanced genome structures were selected to greatly increase in proportion; in such cases, bacteria with better balanced genomes formed larger colonies and grew with shorter generation times. Our results support the hypothesis that genome plasticity as a result of frequent rearrangement provides the opportunity for the bacterial genome to adopt a better balanced structure and thus eventually stabilizes the genome during evolution.
- Published
- 2005
12. A Study on Linseed Oil Modified Waterborne Polyurethane Coatings
- Author
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Chen, Jian Bing, primary, Guo, Qiang, additional, Sun, Jin Liang, additional, Shao, Xian Li, additional, and Nie, Zhi Jun, additional
- Published
- 2011
- Full Text
- View/download PDF
13. Genome Plasticity and ori-ter Rebalancing in Salmonella typhi.
- Author
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Gui-Rong Liu, Wei-Qiao Liu, Johnston, Randal N., Sanderson, Kenneth E., Shao-Xian Li, and Shu-Lin Li
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- 2006
- Full Text
- View/download PDF
14. Effect of terahertz pulse on gene expression in human eye cells.
- Author
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Jin-Wu Zhao, Ming-Xia He, Li-Jie Dong, Shao-Xian Li, Li-Yuan Liu, Shao-Chong Bu, Chun-Mei Ouyang, Peng-Fei Wang, and Long-Ling Sun
- Subjects
RHODOPSIN ,GENE expression ,GENE expression profiling ,SUBMILLIMETER waves ,BIOLOGICAL pigments ,HUMAN genes - Abstract
In recent years, the advances in terahertz applications have stimulated interest in the biological effects associated with this frequency range. We study the gene expression profile in three types of cells exposed to terahertz radiation, i.e., human ARPE-19 retinal pigment epithelial cells, simian virus 40-transformed human corneal epithelial cells, and human MIO-M1 Müller cells. We find that the gene expression in response to heat shock is unaffected, indicating that the minimum temperature increases under controlled environment. The transcriptome sequencing survey demonstrates that 6-hour irradiation with a broadband terahertz source results in specific change in gene expression and also the biological functions that are closely related to these genes. Our results imply that the effect of terahertz radiation on gene expression can last over 15 hours and depends on the type of cell. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
15. Polarization-independent terahertz wave modulator based on graphene-silicon hybrid structure.
- Author
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Fang-Rong Hu, Xian-Ming Xiong, Yan-Feng Li, Liang-Liang Du, Wen-Tao Zhang, Quan Li, Shao-Xian Li, and Jia-Guang Han
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POLARIZATION (Nuclear physics) ,OPTICAL polarization ,OPTICAL resonators ,ELECTRONIC modulators ,LIGHT modulators ,GRAPHENE ,RAMAN spectra ,SCHOTTKY effect - Abstract
In this study, we propose and demonstrate a broadband polarization-independent terahertz modulator based on graphene/silicon hybrid structure through a combination of continuous wave optical illumination and electrical gating. Under a pump power of 400 mW and the voltages ranging from –1.8 V to 1.4 V, modulation depths in a range of –23%–62% are achieved in a frequency range from 0.25 THz to 0.65 THz. The modulator is also found to have a transition from unidirectional modulation to bidirectional modulation with the increase of pump power. Combining the Raman spectra and Schottky current–voltage characteristics of the device, it is found that the large amplitude modulation is ascribed to the electric-field controlled carrier concentration in silicon with assistance of the graphene electrode and Schottky junction. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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