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Search Results: 1 - 10 of 32937 matches for " YuGuo Guo "
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Silicon-based nanomaterials for lithium-ion batteries
YaXia Yin,LiJun Wan,YuGuo Guo
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-5017-2
Abstract: Silicon-based nanomaterials have been of scientific and commercial interest in lithium-ion batteries due to the low cost, low toxicity, and high specific capacity with an order of magnitude beyond that of conventional graphite. The poor capacity retention, caused by pulverization of Si during cycling, triggers researchers and engineers to explore better battery materials. This review summarizes recent work in improving Si-based anode materials via different approaches from diverse Si nanostructures, Si/metal nanocomposites, to Si/C nanocomposites, and also offers perspectives of the Si-based anode materials.
Supercapacitor-battery hybrid energy storage devices from an aqueous nitroxide radical active material
Wei Guo,Sen Xin,MengBo Ji,YuGuo Guo,LiJun Wan
Chinese Science Bulletin , 2011, DOI: 10.1007/s11434-011-4575-z
Abstract: A hybrid electrochemical energy storage device was fabricated in aqueous NaOH with the 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) nitroxide radical as the active material, hydroquinone as the counter electrode active material, and an OH -selective separating membrane. The working principle of this device was investigated and it can be considered as a supercapacitor-battery hybrid energy storage system. Device performance was characterized by cyclic voltammetry and galvanostatic charge-discharge testing. When using multi-walled carbon nanotubes (MWCNTs) as electrode support materials, a high pseudo-capacitance of 1280 F g 1 was obtained with the TEMPO nitroxide radical as the active material at a 1 mV s 1 scan rate. This was ~33 times larger than the inherent double layer capacitance of MWCNTs. The electrode material and active material dissolved in solution could potentially be substituted with similar materials. This simple design provides a new approach for fabricating high performance supercapacitor-battery hybrid energy storage devices.
Controlled fabrication of fullerene derivative one-dimensional nanostructures via electrophoretic deposition of its clusters
Yuguo Guo,Lijun Wan,Chunru Wang,Chunli Bai,Liangbing Gan,Dongmin Chen
Chinese Science Bulletin , 2004, DOI: 10.1360/04wb0080
Abstract: Well-defined and controllable one-dimensional (1D) nanostructures of fullerene derivative have been prepared by an electrophoretic template synthesis method. The clusters of fullerene derivative formed in mixed solvents are introduced into the channels of porous alumina templates through a dc electric field. Four types of 1D nanostructures (solid nanowires, solid-wall nanotubes, porous nanowires and porous-wall nanotubes) have been obtained by changing the deposition parameters. This approach opens a new avenue to assemble fullerene derivatives, endohedral fullerenes, as well as other functional organic compounds, which can form clusters in 1D nanostructure arrays for applications in chemical sensors, light energy conversion devices and nanoscale electronic and optoelectronic devices.
IGF-1 Antibody Prolongs the Effective Duration Time of Botulinum Toxin in Decreasing Muscle Strength
Lingjing Jin,Lizhen Pan,Wuchao Liu,Yan Guo,Yuguo Zheng,Qiang Guan,Zhiyu Nie
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14059051
Abstract: Botulinum toxin type-A (Btx-A), a powerful therapeutic tool in various medical specialties, requires repeated injections to maintain its effect. Therefore, novel methods to prolong the effective duration time of Btx-A are highly needed. Rats were assigned to three major groups: control group ( n = 30), Btx-A group ( n = 30), and IGF-1 Ab groups. IGF-1 Ab groups were composed by sub-groups A1–A5 (each has 25 rats) for the subsequent IGF-1Ab dose-effect study. Muscle strength was determined by a survey system for rat lower limbs nerve and muscle function. Muscle-specific receptor tyrosine kinase (MuSK), Insulin-like growth factor binding protein-5 (IGFBP5), and growth-associated protein, 43-kDa (GAP43) were determined by real-time polymerase chain reactions (PCRs) and Western blot. We found that Btx-A decreased the muscle strength, with a paralysis maintained for 70 days. IGF-1Ab prolonged the effective duration time of Btx-A. Real-time PCRs and Western blot showed that IGF-1Ab delayed the increase of MuSK and IGFBP5 after Btx-A injection, without affecting GAP43. These results indicate that IGF-1Ab might prolong the effective duration time of Btx-A on muscle strength through delaying the increase of MuSK. It would be interesting to determine whether IGF-1Ab can be used as an auxiliary measure to the Btx-A treatment in the future.
Organic Carbon Storage in Four Ecosystem Types in the Karst Region of Southwestern China
Yuguo Liu, Changcheng Liu, Shijie Wang, Ke Guo, Jun Yang, Xinshi Zhang, Guoqing Li
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0056443
Abstract: Karst ecosystems are important landscape types that cover about 12% of the world's land area. The role of karst ecosystems in the global carbon cycle remains unclear, due to the lack of an appropriate method for determining the thickness of the solum, a representative sampling of the soil and data of organic carbon stocks at the ecosystem level. The karst region in southwestern China is the largest in the world. In this study, we estimated biomass, soil quantity and ecosystem organic carbon stocks in four vegetation types typical of karst ecosystems in this region, shrub grasslands (SG), thorn shrubbery (TS), forest - shrub transition (FS) and secondary forest (F). The results showed that the biomass of SG, TS, FS, and F is 0.52, 0.85, 5.9 and 19.2 kg m?2, respectively and the corresponding organic cabon storage is 0.26, 0.40, 2.83 and 9.09 kg m?2, respectively. Nevertheless, soil quantity and corresponding organic carbon storage are very small in karst habitats. The quantity of fine earth overlaying the physical weathering zone of the carbonate rock of SG, TS, FS and F is 38.10, 99.24, 29.57 and 61.89 kg m?2, respectively, while the corresponding organic carbon storage is only 3.34, 4.10, 2.37, 5.25 kg m?2, respectively. As a whole, ecosystem organic carbon storage of SG, TS, FS, and F is 3.81, 4.72, 5.68 and 15.1 kg m?2, respectively. These are very low levels compared to other ecosystems in non-karst areas. With the restoration of degraded vegetation, karst ecosystems in southwestern China may play active roles in mitigating the increasing CO2 concentration in the atmosphere.
Knowledge Reduction and Discovery based on Demarcation Information
Yuguo He
Mathematics , 2004,
Abstract: Knowledge reduction, includes attribute reduction and value reduction, is an important topic in rough set literature. It is also closely relevant to other fields, such as machine learning and data mining. In this paper, an algorithm called TWI-SQUEEZE is proposed. It can find a reduct, or an irreducible attribute subset after two scans. Its soundness and computational complexity are given, which show that it is the fastest algorithm at present. A measure of variety is brought forward, of which algorithm TWI-SQUEEZE can be regarded as an application. The author also argues the rightness of this measure as a measure of information, which can make it a unified measure for "differentiation, a concept appeared in cognitive psychology literature. Value reduction is another important aspect of knowledge reduction. It is interesting that using the same algorithm we can execute a complete value reduction efficiently. The complete knowledge reduction, which results in an irreducible table, can therefore be accomplished after four scans of table. The byproducts of reduction are two classifiers of different styles. In this paper, various cases and models will be discussed to prove the efficiency and effectiveness of the algorithm. Some topics, such as how to integrate user preference to find a local optimal attribute subset will also be discussed.
On the strictness of the quantifier structure hierarchy in first-order logic
Yuguo He
Computer Science , 2014, DOI: 10.2168/LMCS-10(4:3)2014
Abstract: We study a natural hierarchy in first-order logic, namely the quantifier structure hierarchy, which gives a systematic classification of first-order formulas based on structural quantifier resource. We define a variant of Ehrenfeucht-Fraisse games that characterizes quantifier classes and use it to prove that this hierarchy is strict over finite structures, using strategy compositions. Moreover, we prove that this hierarchy is strict even over ordered finite structures, which is interesting in the context of descriptive complexity.
k variables are needed to define k-Clique in first-order logic
Yuguo He
Computer Science , 2015,
Abstract: In an early paper, Immerman raised a proposal on developing model-theoretic techniques to prove lower bounds on ordered structures, which represents a long-standing challenge in finite model theory. An iconic question standing for such a challenge is how many variables are needed to define $k$-Clique in first-order logic on the class of finite ordered graphs? If $k$ variables are necessary, as widely believed, it would imply that the bounded (or finite) variable hierarchy in first-order logic is strict on the class of finite ordered graphs. In 2008, Rossman made a breakthrough by establishing an optimal average-case lower bound on the size of constant-depth unbounded fan-in circuits computing $k$-Clique. In terms of logic, this means that it needs greater than $\lfloor\frac{k} {4}\rfloor$ variables to describe the $k$-Clique problem in first-order logic on the class of finite ordered graphs, even in the presence of arbitrary arithmetic predicates. It follows, with an unpublished result of Immerman, that the bounded variable hierarchy in first-order logic is indeed strict. However, Rossman's methods come from circuit complexity and a novel notion of sensitivity by himself. And the challenge before finite model theory remains there. In this paper, we give an alternative proof for the strictness of bounded variable hierarchy in $\fo$ using pure model-theoretic toolkit, and anwser the question completely for first-order logic, i.e. $k$-variables are indeed needed to describe $k$-Clique in this logic. In contrast to Rossman's proof, our proof is purely constructive. Then we embed the main structures into a pure arithmetic structure to show a similar result where arbitrary arithmetic predicates are presented. Finally, we discuss its application in circuit complexity.
Complete quantum circuit of Haar wavelet based MRA
Yuguo He,Jigui Sun
Chinese Science Bulletin , 2005, DOI: 10.1360/982004-694
Abstract: Wavelet analysis has applications in many areas, such as signal analysis and image processing. We propose a method for generating the complete circuit of Haar wavelet based MRA by factoring butterfly matrices and conditional perfect shuffle permutation matrices. The factorization of butterfly matrices is the essential part of the design. As a result, it is the key point to obtain the circuits of $I_{2t} \oplus W \oplus I_{2^n - 2t - 2} $ In this paper, we use a simple means to develop quantum circuits for this kind of matrices. Similarly, the conditional permutation matrix is implemented entirely, combined with the scheme of Fijany and Williams. The circuits and the ideas adopted in the design are simple and intelligible.
Existence of Positive Solutions for Semipositone Higher-Order BVPS on Time Scales
Yuguo Lin,Minghe Pei
Advances in Difference Equations , 2010, DOI: 10.1155/2010/235296
Abstract: We offer conditions on semipositone function f(t,u0,u1,…,un-2) such that the boundary value problem, uΔn(t)+f(t,u(σn-1(t)),uΔ(σn-2(t)),…,uΔn-2(σ(t)))=0, t∈(0,1)∩ , n≥2, uΔi(0)=0, i=0,1,…,n-3, αuΔn-2(0)-βuΔn-1(0)=0, γuΔn-2(σ(1))+δuΔn-1(σ(1))=0, has at least one positive solution, where is a time scale and f(t,u0,u1,…,un-2)∈C([0,1]× [0,∞)n-1, (-∞,∞)) is continuous with f(t,u0,u1,…,un-2)≥-M for some positive constant M.
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