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Search Results: 1 - 10 of 127127 matches for " Yihong Li "
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Reduced Oral Microbial Diversity in Individuals Harbor Periodontal Diseases
Jinghua Sun,Yihong Li
Dental Hypotheses , 2012,
Abstract: Introduction: Bacteria colonize a variety of surfaces of the hu-man body. The bacterial diversity in the oral cavity is estimated to be more than 700 different species. The oral cavity is home to microbial communities, with important implications for human health and disease. Oral microbial flora is responsible for two major human infectious diseases of the oral cavity, dental caries and periodontal diseases. From the clinical samples, previously, using polymerase chain reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) technique, we found a significantly greater diversity of oral microbes in caries-free individuals compared with caries-active individuals. The hypothesis: We hypothesize that a greater diversity of indigenous bacteria inhabits a healthy oral environment, and that a sig-nificant proportion of oral biota may be absent, suppressed, or replaced in a periodontal diseases environment. Evaluation of the hypothesis: The microbiota undergoes a transition from a commensal to a pathogenic relationship with the host due to factors that trigger a shift in the proportions of resident microorganisms. If our hypothesis is true, many techniques which were used to detect the oral bacterial diversity can be used in diagnosis and prognosis of periodontal diseases.
Liouville type theorems for conformal Gaussian curvature equation
Li Ma,Yihong Du
Mathematics , 2008,
Abstract: In this note, we study Liouville type theorem for conformal Gaussian curvature equation (also called the mean field equation) $$ -\Delta u=K(x)e^u, in R^2 $$ where $K(x)$ is a smooth function on $R^2$. When $K(x)=K(x_1)$ is a sign-changing smooth function in the real line $R$, we have a non-existence result for the finite total curvature solutions. When $K$ is monotone non-decreasing along every ray starting at origin, we can prove a non-existence result too. We use moving plane method and moving sphere method.
The existence results for solutions of indefinite scalar curvature problem
Li Ma,Yihong Du
Mathematics , 2008,
Abstract: In this paper, we consider the indefinite scalar curvature problem on $R^n$. We propose new conditions on the prescribing scalar curvature function such that the scalar curvature problem on $R^n$ (similarly, on $S^n$) has at least one solution. The key observation in our proof is that we use the bifurcation method to get a large solution and then after establishing the Harnack inequality for solutions near the critical points of the prescribed scalar curvature and taking limit, we find the nontrivial positive solution to the indefinite scalar curvature problem.
Assessment of the Spatial and Temporal Water Eutrophication for Lake Baiyangdian Based on Integrated Fuzzy Method  [PDF]
Shuxuan Liang, Hong Wu, Yihong Wu, Hongbo Li
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.41013
Abstract:

Water quality evaluation entails both randomness and fuzziness. Considering that water eutrophication evaluation involves many indices, different classifications and interval values, fuzzy variable sets theory was developed to Lake Baiyangdian as a study case. Taking reference to eutrophication standard of Chinese lakes and local characteristic of Lake Baiyangdian, eutrophication degree of lake was divided into 8 levels. Total phosphorus, total nitrogen, and CODMn were selected as evaluation indices in this research. Based on the measured data, index feature value matrix of sample was built. Index weights were determined by means of pure threshold value method. Relative membership degree of each index to each classification was calculated with relative difference function model. Then the stability of feature value of classification corresponding was received by the comprehensive calculation with the relative membership degree and index weights. The results show that the proposed models are effective tools for generating a set of realistic and flexible optimal solutions for complicated water quality evaluation issues. It concluded that the model was reasonable and practical.

Dynamic Modeling and Analysis of the Email Virus Propagation
Yihong Li,Jinxiao Pan,Zhen Jin
Discrete Dynamics in Nature and Society , 2012, DOI: 10.1155/2012/472072
Abstract: A novel deterministic SEIS model for the transmission of email viruses in growing communication networks is formulated. Interestingly, the model is different from classical SEIS models not only in the form, but also in the dynamical features. We study the equilibria and their stability and analyse the bifurcation dynamics of the model. In particular, we find that the virus-free equilibrium is locally asymptotically stable for any parameter values, which may attribute to the absence of the basic reproduction number. It is shown that the model undergoes a saddle-node bifurcation and admits the bistable phenomenon. Moreover, on the basis of the Lyapunov function, the domains of attraction of equilibria are estimated by solving an LMI optimization problem. Based on the above theoretical results, some effective strategies are also provided to control the propagation of the email viruses. Additionally, our results are confirmed by numerical simulations.
Homogeneous Isolation of Nanocellulose from Cotton Cellulose by High Pressure Homogenization  [PDF]
Yihong Wang, Xiaoyi Wei, Jihua Li, Qinghuang Wang, Fei Wang, Lingxue Kong
Journal of Materials Science and Chemical Engineering (MSCE) , 2013, DOI: 10.4236/msce.2013.15010
Abstract: Nano-cellulose materials are widely believed to have the potential to push polymer mechanical properties. The cotton cellulose was dissolved in ionic liquid (1-butyl-3-methylimidazolium chloride ([Bmim]Cl)), and then was isolated by high pressure homogenization in a homogeneous media. The nano-cellulose was obtained at 80MPa for 30 cycles. The geometry and microstructure of the cellulose nano-fibres were observed by SEM and their particle size analysis. FTIR, XRD and TGA were used to characterize changes to chemical functionality. Particular emphasis is given to the physical and chemical characterization of these nano-fibres together with their thermal stability and crystallinity, in order to develop their suitability.
Characterizing Diversity of Lactobacilli Associated with Severe Early Childhood Caries: A Study Protocol  [PDF]
Yihong Li, Silvia Argimón, Catherine N. Sch?n, Prakaimuk Saraithong, Page W. Caufield
Advances in Microbiology (AiM) , 2015, DOI: 10.4236/aim.2015.51002
Abstract: Lactobacilli have been consistently associated with dental caries for decades; however, knowledge of this group of bacteria in the etiology of the disease is limited to quantitative elucidation. Nowadays, explicit identification of oral Lactobacillus species is possible, despite their taxonomic complexity. Here we describe a combined approach involving both cultivation and genetic methods to ascertain and characterize the diversity and abundance of the Lactobacillus population in the oral cavities of children with severe early childhood caries (S-ECC). Eighty 3- to 6-year-old children (40 S-ECC and 40 caries free) who were seeking dental care at the Pediatric Dental Clinic of Bellevue Hospital in New York City were invited to participate in this study. Clinical data on sociodemographic information and oral health behavior were obtained from the primary caregiver. The data included a detailed dental examination, children’s medical history, and a questionnaire survey. Combined non-stimulated saliva and supragingival plaque samples were collected from each child and cultivated on selective media for quantitative measures of lactobacilli levels. The procedure for Lactobacillus species screening will include the random selection of 50 colonies per plate, ex- traction of DNA from each colony, and genotyping by arbitrarily primed polymerase chain reaction (AP-PCR). Each unique Lactobacillus AP-PCR genotype will be selected for taxonomic assessment by 16S rRNA gene sequencing analysis. Lactobacillus species will be identified by comparing the 16S rRNA sequences with the Ribosomal Database and the Human Oral Microbiome Database. Meanwhile, the same set of clinical samples will be independently subjected to genomic DNA isolation, 16S rRNA amplification with Lactobacillus genus-specific primers, sequencing, and taxonomic identification, both at genus and species levels with a customized pipeline. The distribution and phylogenetic differences of these Lactobacillus species will be compared between children with or without S-ECC. One of the main objectives of this study is to establish a study protocol for the identification and characterization of lactobacilli in the oral cavity. Future caries risk assessments can include lactobacilli counts (quantitative) and the presence/absence of specific cario- genic genetic signatures of a Lactobacillus species (qualitative) associated with S-ECC.
Construction of Global Weak Entropy Solution of Initial-Boundary Value Problem for Scalar Conservation Laws with Weak Discontinuous Flux  [PDF]
Yihong Dai, Jing Zhang
American Journal of Computational Mathematics (AJCM) , 2017, DOI: 10.4236/ajcm.2017.74033
Abstract: This paper is concerned with the initial-boundary value problem of scalar conservation laws with weak discontinuous flux, whose initial data are a function with two pieces of constant and whose boundary data are a constant function. Under the condition that the flux function has a finite number of weak discontinuous points, by using the structure of weak entropy solution of the corresponding initial value problem and the boundary entropy condition developed by Bardos-Leroux-Nedelec, we give a construction method to the global weak entropy solution for this initial-boundary value problem, and by investigating the interaction of elementary waves and the boundary, we clarify the geometric structure and the behavior of boundary for the weak entropy solution.
Large Induces Functional Glycans in an O-Mannosylation Dependent Manner and Targets GlcNAc Terminals on Alpha-Dystroglycan
Yihong Hu,Zhi-fang Li,Xiaohua Wu,Qilong Lu
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0016866
Abstract: Alpha-dystroglycan (α-DG) is a ubiquitously expressed receptor for extracellular matrix proteins and some viruses, and plays a pivotal role in a number of pathological events, including cancer progression, muscular dystrophies, and viral infection. The O-glycans on α-DG are essential for its ligand binding, but the biosynthesis of the functional O-glycans remains obscure. The fact that transient overexpression of LARGE, a putative glycosyltransferase, up-regulates the functional glycans on α-DG to mediate its ligand binding implied that overexpression of LARGE may be a novel strategy to treat disorders with hypoglycosylation of α-DG. In this study, we focus on the effects of stable overexpression of Large on α-DG glycosylation in Chinese hamster ovary (CHO) cell and its glycosylation deficient mutants. Surprisingly, stable overexpression of Large in an O-mannosylation null deficient Lec15.2 CHO cells failed to induce the functional glycans on α-DG. Introducing the wild-type DPM2 cDNA, the deficient gene in the Lec15.2 cells, fully restored the Large-induced functional glycosylation, suggesting that Large induces the functional glycans in a DPM2/O-mannosylation dependent manner. Furthermore, stable overexpression of Large can effectively induce functional glycans on N-linked glycans in the Lec8 cells and ldlD cells growing in Gal deficient media, in both of which circumstances galactosylation are deficient. In addition, supplement of Gal to the ldlD cell culture media significantly reduces the amount of functional glycans induced by Large, suggested that galactosylation suppresses Large to induce the functional glycans. Thus our results revealed a mechanism by which Large competes with galactosyltransferase to target GlcNAc terminals to induce the functional glycans on α-DG.
A Novel Dual-Band Patch Antenna with Complementary Split Ring Resonators Embedded in the Ground Plane
Yihong Xie;Long Li;Cheng Zhu;Chang-Hong Liang
PIER Letters , 2011, DOI: 10.2528/PIERL11062802
Abstract: In this paper, a novel design of dual-band microstrip antenna with complementary split ring resonators (CSRRs) is presented. A simple and successful dual-band antenna can be realized by etching three CSRRs in the ground plane of a conventional patch antenna. The proposed antenna shows good performances at both resonant frequencies. The CSRRs embedded in the ground plane make a major contribution to the first operating band, but has minor effect on the second operating band. It is beneficial for designing a dual-band antenna as well as a miniaturized antenna flexibly. The simulation results are analyzed and compared with measured results in a good agreement.
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