21 results on '"Xin-xing, Liu"'
Search Results
2. Dyadobacter diqingensis sp. nov., isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China
- Author
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Lei Ran, Man Peng, Wei-Qun Wang, Yu-Zhou Feng, Juan Wang, Yu Wang, Cui-Ying Li, Xin-Xing Liu, Wei-Xun Chunyu, and Shu-Kun Tang
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DNA, Bacterial ,China ,Cytophagaceae ,Fatty Acids ,General Medicine ,Sequence Analysis, DNA ,Tibet ,Biochemistry ,Microbiology ,Bacterial Typing Techniques ,RNA, Ribosomal, 16S ,Snow ,Genetics ,Molecular Biology ,Phospholipids ,Phylogeny - Abstract
A Gram-negative, aerobic, nonmotile, rod-shaped and yellow-pigment-producing bacteria was isolated from Baima snow mountain of Diqing Tibetan Autonomous Prefecture in Yunnan province, south-west China and characterized using a polyphasic approach. The results of 16S rRNA gene sequence similarity analysis showed that strain YIM B04101
- Published
- 2022
3. [Endogenous Release of Nitrogen and Phosphorus in the Danjiangkou Reservoir]
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Zhi-Qi, Wang, Xin-Xing, Liu, Zhi-Hong, Yao, Lun-Guang, Yao, Yue, Chang, Zhuo-Chu, Liu, and Lian-Hai, Cao
- Abstract
In situ sediments were collected at different sites of the Danjiangkou Reservoir using a columnar sediment sampler, and the release rate of N and P at the sediment-water interface was determined through static incubation experiments and the diffusion model of interstitial water molecules. The results showed that there was a significant difference in the release rate for N and P from sediments collected at five sampling sites. The release rates of NH
- Published
- 2019
4. [Genetic Diversity and Cluster Analysis of Astragalus membranaceus in Gansu Province]
- Author
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Yi-qin, Hou, Yan-ping, Zhang, You-tai, Shi, Xin-xing, Liu, and Yu-liang, Chen
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Polymorphism, Genetic ,Cluster Analysis ,Genetic Variation ,Astragalus propinquus - Abstract
To investigate the genetic status of Astragalus membranaceuse resources in Gansu province.Using SSR molecular marker technology for collection of Astragalus membranaceuse resources for genetic diversity analysis and clustering analysis.Nine SSR primers were used on PCR amplification of 57 samples in six main areas of Gansu province,PCR products molecular weighted between 100 ~ 500 bp,the polymorphic loci was 82,the polymorphism rate was 97. 56%,and the average polymorphism information content was 0. 438. At the species level,the number of alleles was 1. 976,the effective number of alleles was 1. 459,Nei’ s genetic diversity was 0. 279,Shannon information index was 0. 431,the group of genetic diversity degree was 0. 248,the genetic differentiation among of population was 0. 117,the gene flow coefficient was 3. 775,and the genetic identity was 0. 896 ~ 0. 977.Astragalus membranaceuse resources of Gansu are relatively pure,and have abundant genetic diversity. The genetic variation mainly comes from the group of inside,the genes communication between populations is frequent,and the kinship between population is consistent with their geographic distance. In addition,the results of cluster analysis showed that the Core SSR primers can distinguish Astragalus and Hedysarum in the similarity of 0. 46,but Astragalus membranaceus var. mongholicus,Astragalus membranaceus and Astragalus tongolensis can’t be distinguished.
- Published
- 2018
5. The Paradoxes of Big Data
- Author
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Xin Xing Liu, Xing Wu, and Shu Ji Dai
- Subjects
business.industry ,Computer science ,Scale (chemistry) ,Big data ,The Internet ,General Medicine ,business ,Data science - Abstract
The era of Big Data poses a big challenge to our way of living and thinking. Big Data refers to things which can do at a large scale but cannot be done at a smaller size. There are many paradoxes of Big Data: In this new world far more data can be analyzed, though using all the data can make the datum messy and lose some accuracy, sometimes reach better conclusions. As massive quantities of information produced by and about people and their interactions exposed on the Internet, will large scale search and analyze data help people create better services, goods and tools or it just lead to privacy incursions and invasive marketing? In this article, we offer three main provocations, based on our analysis we have constructed some models to help explain the amazing contradiction in Big Data.
- Published
- 2015
- Full Text
- View/download PDF
6. High photon-to-heat conversion efficiency in the wavelength region of 250–1200 nm based on a thermoelectric Bi2Te3 film structure
- Author
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Jia Jin Zheng, Wei Wei, David W. Lynch, Hai Bin Zhao, An Qing Jiang, Liang Yao Chen, Xin Xing Liu, Yuan Yao, Kehan Yu, Songyou Wang, Jun Peng Guo, Er Tao Hu, Cai-Zhuang Wang, Osamu Yoshie, Rong Jun Zhang, YoungPak Lee, Kai Yan Zang, and Yu-Xiang Zheng
- Subjects
Multidisciplinary ,Materials science ,business.industry ,Energy conversion efficiency ,02 engineering and technology ,Sputter deposition ,021001 nanoscience & nanotechnology ,01 natural sciences ,Article ,010309 optics ,Wavelength ,Solar cell efficiency ,0103 physical sciences ,Thermoelectric effect ,Optoelectronics ,Thermal emittance ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) ,Layer (electronics) - Abstract
In this work, 4-layered SiO2/Bi2Te3/SiO2/Cu film structures were designed and fabricated and the optical properties investigated in the wavelength region of 250–1200 nm for their promising applications for direct solar-thermal-electric conversion. A typical 4-layered film sample with the structure SiO2 (66.6 nm)/Bi2Te3 (7.0 nm)/SiO2 (67.0 nm)/Cu (>100.0 nm) was deposited on a Si or K9-glass substrate by magnetron sputtering. The experimental results agree well with the simulated ones showing an average optical absorption of 96.5%, except in the shorter wavelength region, 250–500 nm, which demonstrates the superior absorption property of the 4-layered film due to the randomly rough surface of the Cu layer resulting from the higher deposition power. The high reflectance of the film structure in the long wavelength region of 2–20 μm will result in a low thermal emittance, 0.064 at 600 K. The simpler 4-layered structure with the thermoelectric Bi2Te3 used as the absorption layer may provide a straightforward way to obtain solar-thermal-electric conversion more efficiently through future study.
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- 2017
- Full Text
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7. Information Extraction and Metallogenic Prediction of Qiangduo Area in Tibet Based on Multi-Source Remote Sensing Data
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Xin Xing Liu
- Subjects
Information extraction ,General Engineering ,Prospecting ,Earth remote sensing ,computer.software_genre ,Geologic map ,Data type ,computer ,Multi-source ,Geology ,Multispectral pattern recognition ,Geological structure ,Remote sensing - Abstract
Remote sensing technology as a kind of new and advanced technology has been playing an important role in geological mapping and prospecting. A single kind of remote sensing data always has both advantages and disadvantages. And with multispectral remote sensing data types increasing, the integrated application of multi-source remote sensing data will be one of the development trend of remote sensing geology. In this paper, comprehensive utilization of multi-source remote sensing data such as ETM+, ASTER, Worldview-II and DEM, lithology and geological structure of Qiangduo area in Tibet were interpreted in different levels and mineralized alteration information also was extracted. Then on the basis of modern metallogenic theory, analyzed the multiple mineralization favorite information, established the remote sensing prediction model, and on the GIS platform, carried out metallogenic prediction of the study area. The field validation shows that the results of the prediction are relatively accurate and remote sensing technology can improve the efficiency of geological work.
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- 2014
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8. Software and Hardware Design of Signal Acquisition System about Electro-Hydraulic Control System of Hydraulic Support
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Peng Xia, Yong Qi Liu, Xin Xing Liu, Yan Yan Wang, Xi Zhang, and Ya Bin Cui
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Engineering ,business.industry ,Control (management) ,Work (physics) ,General Engineering ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Control engineering ,Column (database) ,Displacement (vector) ,Signal acquisition ,Control function ,Software ,Control system ,business ,Computer hardware - Abstract
Electro-hydraulic control system of hydraulic support in addition to being able to control the basic movements of hydraulic support, also can work for signal acquisition of mining environment, including pressure of column pressure, displacement of push lutetium and pull support etc. The electro-hydraulic control system is presented in this paper, on the basis of the original control function added signal acquisition module, and designed the hardware and software.
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- 2014
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9. The Design of Force-Displacement Characteristics Test System for Electromagnet
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Ya Bin Cui, Xi Zhang, Xin Xing Liu, Miao Yu, and Peng Xia
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Engineering ,Electromagnet ,business.industry ,Electrical engineering ,Mechanical engineering ,General Medicine ,Physics::Classical Physics ,Automation ,Pressure sensor ,Displacement (vector) ,law.invention ,Data acquisition ,Software ,Hardware_GENERAL ,law ,Control system ,business ,Force displacement - Abstract
Electromagnet for valve is a key executive device of electromagnetic valve control system, as a dynamic element, force and displacement characteristics of electromagnet, directly affect the reliable performance of devices made of it. By reference to other electromagnet testing standard and method, proposed a based on vc6.0 and stepper motor of force and displacement characteristics for electromagnet test system. The system consists mechanical platform, pressure sensor, data acquisition card and PC test software. The system is easy to operate, high degree of automation, stable performance. Provides an auxiliary electromagnet selection testing and inspection tools, can improve the work efficiency.
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- 2013
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10. A surgery protocol to construct zebrafish heart damage and regeneration model
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Bo Zhang, Xin-Xing Liu, and Yu-Tian Zhang
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Heart Injury ,biology ,Regeneration (biology) ,medicine.medical_treatment ,General Medicine ,Anatomy ,biology.organism_classification ,Bioinformatics ,medicine.disease ,Regenerative medicine ,medicine.anatomical_structure ,Amputation ,Ventricle ,medicine ,Pericardium ,Myocardial infarction ,Zebrafish - Abstract
In recent years, zebrafish has been found to be strikingly capable of heart regeneration at adult stage, which sheds lights on cardiac regenerative medicine, and has also become an important direction for the study of vertebrate genetic and developmental mechanisms. Dissecting the regeneration process and unraveling the underlying molecular and cellular mechanisms might help recover the regeneration capacity of the mammalian heart and further provide instructions to potential therapies for certain cardiac diseases such as myocardial infarction. Here, we introduced a simple surgical method to construct heart injury and regeneration model in zebrafish through amputation of ~20% ventricle. The main procedure includes anaesthetization of adult zebrafish, exposure of the heart by dissecting the nearby abdominal skin and opening the pericardium, and amputation of certain fraction of the ventricle at the cardiac apex under a stereo microscope. Over 90% success rate and easy handling with high reproducibility enable this method to be the most commonly used one for the study of zebrafish heart regeneration.
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- 2013
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11. Astragali Radix and Hedysari Radix molecular identification of SSR primers screening and fingerprints code
- Author
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You-tai Shi, Hou Yiqing, Zhang Yanping, Yu-liang Chen, and Xin-xing Liu
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Gel electrophoresis ,Chromatography ,Pcr cloning ,Fabaceae ,Astragalus Plant ,Biology ,DNA Fingerprinting ,Plant Roots ,Polymerase Chain Reaction ,Complementary and alternative medicine ,Pharmacology (medical) ,Radix ,Polymorphic locus ,General Pharmacology, Toxicology and Pharmaceutics ,Primer (molecular biology) ,DNA Primers ,Molecular identification - Abstract
Leguminous related SSR primers were collected, core primers used for Astragali Radix and Hedysari Radix identification were screened and validated by using molecular marker techniques. 6 core primers were selected from 101 pairs of primers, the molecular weight of PCR products was 100-500 bp, which formed 7-12 electrophoresis bands with 55 amplified loci. The percentage of polymorphic loci was 100%, and the average polymorphism information content was 0.371. According to the results of cluster analysis, obtained core primer could completely distinguish 62 mixture samples of Astragali Radix and Hedysari Radix in similarity coefficient of 0.46. Core primers and the corresponding characteristics from gel electrophoresis were tagged. The results provide identification basis for Astragali Radix and Hedysari Radix.
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- 2016
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12. Electrokinetic Remediation of Heavy Metal Contaminated Soil Using Permeable Reactive Composite Electrodes
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Jin Ma, Fang Liu, Jiang Zhu, Rong Bing Fu, Yu Mei Ma, Xin Xing Liu, and Chang Bo Zhang
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Electrolysis ,Chromatography ,Materials science ,Electrokinetic remediation ,Environmental remediation ,Metal ions in aqueous solution ,Inorganic chemistry ,General Engineering ,Soil contamination ,law.invention ,Metal ,law ,Soil pH ,visual_art ,visual_art.visual_art_medium ,Zeolite - Abstract
A new permeable reactive composite electrode (PRCE) attached with a permeable reactive layer (PRL) of Fe0 and zeolite has been developed for soil pH control and the improved removal efficiency of heavy metal ions (Cd, Ni, Pb, Cu) from soil in electrokinetic remediation process. The effects of different composite electrodes on pH control and heavy metal removal efficiency were studied, and changes in the forms of heavy metals moved onto the electrodes were analyzed. The results showed that with acidic/alkaline zeolite added and renewed in time, the composite electrodes could effectively neutralize and capture H+ and OH- produced from electrolysis of the anolyte and catholyte, avoiding or delaying the formation of acidic/alkaline front in tested soil, preventing premature precipitation of heavy metal ions and over-acidification of soil, and thus significantly improved the heavy metal removal efficiency. Fe0 in composite electrodes could deoxidize and stabilize the heavy metal ions. After that capture and immobilization of the pollutants were achieved. The results also showed that, using "Fe0 + zeolite" PRCE in the cathode with timely renewal, after 15-day remediation with a DC voltage of 1.5 V/cm, the total removal rates of Cd, Pb, Cu and Ni were 49.4%, 47.1%, 36.7% and 39.2%, respectively.
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- 2012
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13. Multilayered metal-dielectric film structure for highly efficient solar selective absorption
- Author
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Liang Yao Chen, Songyou Wang, Er Tao Hu, Kai Yan Zang, Hai Bin Zhao, David W. Lynch, Jia Jin Zheng, Wei Wei, Rong Jun Zhang, An Qing Jiang, Jun Peng Guo, Xin Xing Liu, Yuan Yao, Zong Jie Tu, Osamu Yoshie, Cai-Zhuang Wang, YoungPak Lee, Yu-Xiang Zheng, and Kehan Yu
- Subjects
Materials science ,Polymers and Plastics ,business.industry ,Transfer-matrix method (optics) ,Metals and Alloys ,02 engineering and technology ,Dielectric ,Sputter deposition ,Radiation ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Selective surface ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Biomaterials ,Absorptance ,Optoelectronics ,Thermal emittance ,0210 nano-technology ,business ,Absorption (electromagnetic radiation) - Abstract
To improve the optical absorptance of a solar selective absorber over a wide wavelength range, an eight-layered metal-dielectric film structure was designed by the transfer matrix method and fabricated with the magnetron sputtering method. The experimental results showed that the multilayered film structure yields a high solar absorptance of 98.3% with excellent spectral selectivity over a wide angular range in the solar radiation region of 250–2000 nm, a total hemispherical emittance of 0.12 at 400 K, and nearly unchanged reflectance after heat treatment at 673 K for 48 h in vacuum, indicating the high efficiency of the photo-to-thermal conversion achieved for the sample to have the potential being practically applied in many fields.
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- 2018
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14. Tunable optical properties of co-sputtered Ti-SiO_2 nanocomposite thin films
- Author
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Ertao Hu, Yu-Xiang Zheng, Xin Xing Liu, Xiangxing Xu, Kai-Yan Zang, Yuan Yao, Wei Wei, Kehan Yu, Songyou Wang, Liang-Yao Chen, Rong-Jun Zhang, and Qing-Yuan Cai
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Materials science ,Nanocomposite ,business.industry ,Direct current ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Electronic, Optical and Magnetic Materials ,Titanium oxide ,010309 optics ,X-ray photoelectron spectroscopy ,Ellipsometry ,0103 physical sciences ,Optoelectronics ,Photonics ,Thin film ,0210 nano-technology ,business ,Deposition (law) - Abstract
In this work, optical constants of direct current (DC) and radio frequency (RF) co-sputtered Ti-SiO2 nanocomposite thin films were investigated and tuned by controlling the deposition power of Ti in the SiO2 host matrix. X-ray photoelectron spectroscopy (XPS) results confirmed that the metallic Ti was completely oxidized into different titanium oxide states while the Si4+ state was reduced to the Si2+ or Si0 state by observing the Ti 2p, O 1s and Si 2p line shapes changing under different deposition conditions. The optical constants of the composites were characterized with a spectroscopic ellipsometer (SE) and reduced by using the modified harmonic oscillator approximation (HOA) model. The results show that the metal-dielectric nanocomposite will have an advantage over natural materials because its optical properties of n and k can be properly tuned by adjusting the concentration of Ti in the Ti-SiO2 nanocomposites, thus satisfying the requirements of photonic device design and applications in broad spectral regions.
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- 2017
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15. The reliability of Big Data
- Author
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Shuji Dai, Xin Xing Liu, and Xing Wu
- Subjects
Small data ,Computer science ,business.industry ,Big data ,Volume (computing) ,computer.software_genre ,Data science ,Data point ,Lead (geology) ,Data quality ,Data mining ,business ,computer ,Randomness ,Reliability (statistics) - Abstract
The era of Big Data is underway. Compared to Small Data, machine learning, computerized databases and other modern technologies makes it possible for Big Data to do handle massive data and reveal information in a way that individual bits of data can't. Random sampling's accuracy depends on ensuring randomness when collecting data from samples. Analyzing only a limited number of data points means errors may get amplified, which may reduce the accuracy of the overall results potentially. Meanwhile, Big Data gathers and analyzes massive data to produce some excellent results that we could never know when we are limited to smaller quantities, like address various societal ills, offer potential of new insights into diverse fields. But as the data comes from an environment of uncertainty and rapid change, bigger data may not a better data. Increasing the volume of data may lead to inaccuracy, but in return for relaxing the standards of allowable errors, which produces more valuable information and better results. This article elaborates the reliability of Big Data. Based on our analysis we have constructed a model to analyze the reliability of Big Data.
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- 2014
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16. [A surgery protocol to construct zebrafish heart damage and regeneration model]
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Xin-Xing, Liu, Yu-Tian, Zhang, and Bo, Zhang
- Subjects
Male ,Disease Models, Animal ,Immobilization ,Heart Injuries ,Animals ,Regeneration ,Female ,Heart ,Cardiac Surgical Procedures ,Zebrafish - Abstract
In recent years, zebrafish has been found to be strikingly capable of heart regeneration at adult stage, which sheds lights on cardiac regenerative medicine, and has also become an important direction for the study of vertebrate genetic and developmental mechanisms. Dissecting the regeneration process and unraveling the underlying molecular and cellular mechanisms might help recover the regeneration capacity of the mammalian heart and further provide instructions to potential therapies for certain cardiac diseases such as myocardial infarction. Here, we introduced a simple surgical method to construct heart injury and regeneration model in zebrafish through amputation of ~20% ventricle. The main procedure includes anaesthetization of adult zebrafish, exposure of the heart by dissecting the nearby abdominal skin and opening the pericardium, and amputation of certain fraction of the ventricle at the cardiac apex under a stereo microscope. Over 90% success rate and easy handling with high reproducibility enable this method to be the most commonly used one for the study of zebrafish heart regeneration.
- Published
- 2013
17. [Detection of dynamic expression of microRNAs in vivo using a dual-fluorescence reporter system/miRNA Tracer in zebrafish]
- Author
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Hong-Bo, Yang, Wei, Liang, Xin-Xing, Liu, Zuo-Yan, Zhu, Shuo, Lin, and Bo, Zhang
- Subjects
Animals, Genetically Modified ,MicroRNAs ,Genes, Reporter ,Gene Expression Profiling ,Gene Order ,Animals ,Gene Expression ,Gene Expression Regulation, Developmental ,Zebrafish ,Plasmids - Abstract
microRNAs (miRNAs) are short noncoding RNAs that have been found in a wide variety of organisms and many have been shown to play essential roles by regulating the stability and translation of target messenger RNAs (mRNAs) in animals and plants. Temporal and spatial expression is critical for the regulatory function of miRNAs. To analyze the dynamic expression of particular miRNA in vivo, we constructed a dual-fluorescence reporter system based on Tol2 transposon, in which two reporter genes, enhanced green fluorescent protein (eGFP) and monomeric red fluorescent protein 1 (mRFP1), were driven by the heat shock promoter (hsp) from zebrafish hsp70 gene in an opposite orientation. To sense the existence of a particular miRNA, the complementary DNA sequence of the corresponding miRNA was inserted into the 3'-UTR region of one of the two reporter genes. By injecting the corresponding plasmid DNA into zebrafish embryos, we were able to monitor the abundance and dynamics of miRNA miR-206 in live embryos. To further evaluate this method, we made a collection of transgenic zebrafish with stable integration of dual-fluorescence reporter plasmids targeting different miRNAs, including miR-206 and miR-219. Our results showed that this dual-fluorescence reporter system, which is also called miRNA Tracer, could faithfully monitor the appearance and disappearance of target miRNAs in defined cell lineages during zebrafish development in these fish lines. Our dual-fluorescence reporter/Tracer system provides an important tool for further in-depth studies on miRNAs in zebrafish.
- Published
- 2012
18. MICROBIAL COMMUNITY DIVERSITY OF MINE AREA DECREASES UNDER INCREASING CADMIUM STRESS.
- Author
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Ling Tan, Hui Yun, Li-ting Huang, Jie Chen, Hao-yi He, Ying Pan, Jia He, Er-ping Li, Xin-xing Liu, and Jian-ping Xie
- Abstract
Cadmium (Cd) is a highly toxic heavy metal since it contaminates environment and even poses a threat on human health. This work focuses on the dynamic changes of diversity and composition of the microbial community in mine area with an increasing stress of Cd
2+ . Community composition of different samples was analyzed using PCR-RFLP. The results showed that, with the growing of Cd2+ stress, diversity of community declined, and composition of microbial community reduced from 11 phyla in original sample to a single strain. Since no reference sequence in NCBI library was identical to the 16S rDNA sequence of this cadmiumresistance strain, it might be a new strain, and the 16S rDNA sequence was committed to NCBI as accession number of KU534597. [ABSTRACT FROM AUTHOR]- Published
- 2016
19. High material quality growth of AlInAsSb thin films on GaSb substrate by molecular beam epitaxy.
- Author
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Fa-Ran Chang, Rui-Ting Hao, Tong-Tong Qi, Qi-Chen Zhao, Xin-Xing Liu, Yong Li, Kang Gu, Jie Guo, Guo-Wei Wang, Ying-Qiang Xu, and Zhi-Chuan Niu
- Subjects
THIN films ,MOLECULAR beam epitaxy ,GALLIUM antimonide ,SUBSTRATES (Materials science) ,X-ray diffraction ,FOURIER transform infrared spectroscopy - Abstract
In this paper, high material quality Al
0.4 In0.6 AsSb quaternary alloy on GaSb substrates is demonstrated. The quality of these epilayers is assessed using a high-resolution x-ray diffraction, Fourier transform infrared (FTIR) spectrometer, and atomic force microscope (AFM). The x-ray diffraction exhibits high order satellite peaks with a measured period of 31.06 Å (theoretical value is 30.48 Å), the mismatch between the GaSb substrate and AlInAsSb achieves −162 arcsec, and the root-mean square (RMS) roughness for typical material growths has achieved around 1.6 Å over an area of . At room temperature, the photoluminescence (PL) spectrum shows a cutoff wavelength of . [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
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20. Multilayered metal-dielectric film structure for highly efficient solar selective absorption.
- Author
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Er-Tao Hu, Xin-Xing Liu, Yuan Yao, Kai-Yan Zang, Zong-Jie Tu, An-Qing Jiang, Ke-Han Yu, Jia-Jin Zheng, Wei Wei, Yu-Xiang Zheng, Rong-Jun Zhang, Song-You Wang, Hai-Bin Zhao, Osamu Yoshie, Young-Pak Lee, Cai-Zhuang Wang, David W Lynch, Jun-Peng Guo, and Liang-Yao Chen
- Published
- 2018
- Full Text
- View/download PDF
21. BINDING OF IONIC SURFACTANTS ON OPPOSITELY CHARGED POLYELECTROLYTES OBSERVED BY FLUORESCENCE METHODS.
- Author
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Zhen Tong, Chao-yang Wang, Bi-ye Ren, Min-zhi, Xin-xing Liu, Min-zhi, and Fang Zeng
- Subjects
- *
POLYELECTROLYTES , *SURFACE active agents , *FLUORIMETRY , *COMPLEX compounds - Abstract
Our recent studies concerning the binding of ionic surfactants on oppositely charged polyelectrolytes observed with fluorescence techniques are reviewed. The cationic surfactants cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium chloride (DTAC), and nonoionic surfactant octaethylene glycol monododecyl ether (C[sub 12]E[sub 8]) were allowed to bind on anionic poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and its pyrene and/or naphthalene labeled copolymers. The relative excimer emission intensity I[sub E]/I[sub M] of a cationic probe 1-pyrenemethylamine hydrochloride (PyMeA-HCI) and the non-radiative energy transfer (NRET) I[sub Py]/I[sub Np] of naphthalene to pyrene for labeled polyelectrolytes were chosen to monitor the binding process~ and the conformation change of surfactant-bound polyelectrolytes. The I:I aggregation of polyelectrolyte-CTAB with respect to the charge was found as long as the CTAB concentration was slightly higher than its critical aggregation concentration (CAC). The intermolecular NRET indicated that the CTAB-bound polyelectrolytes aggregated together through the hydrophobic interaction between the CTAB tails. However, neither I:I polyelectrolyte-IDTAC aggregated nor intermolecular aggregation of DTAC-bound polyelectro1yte was observed owing to its weaker hydrophobicity of 12 carbon atoms in the tail, which is shorter than that of CTAB. As known from the fluorescence results, nomionic surfactant C[sub 12]E[sub 8] did not bind on the anionic polyelectrolytes, but the presence of PAMPS promoted the micelle formation for C[sub 12]E[sub 8] at the CAC slighty below its critical micelle concentration (CMC). The solid complex of dansyl labeled AMPS copolymer-surtfactant exhibited a decrease in local polarity with increasing charge density of the polyelectrolyte or with alkane tail length of the surtactant, SAXS suggested a lamella structure for the AMPS copolymer- surfactant solid complexes with a long period of 3.87 nm for CTAB and 3.04 nm for DTAC, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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