137 research outputs found

    Asymptotic lower bounds for Gallai-Ramsey functions and numbers

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    For two graphs G,HG,H and a positive integer kk, the \emph{Gallai-Ramsey number} grk(G,H){\rm gr}_k(G,H) is defined as the minimum number of vertices nn such that any kk-edge-coloring of KnK_n contains either a rainbow (all different colored) copy of GG or a monochromatic copy of HH. If GG and HH are both complete graphs, then we call it \emph{Gallai-Ramsey function} GRk(s,t){\rm GR}_k(s,t), which is the minimum number of vertices nn such that any kk-edge-coloring of KnK_n contains either a rainbow copy of KsK_s or a monochromatic copy of KtK_t. In this paper, we derive some lower bounds for Gallai-Ramsey functions and numbers by Lov\'{o}sz Local Lemma.Comment: 11 page

    Nonlinear Model Predictive Control for the Stabilization of a Wheeled Unmanned Aerial Vehicle on a Pipe

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    This letter addresses the task of stabilizing a wheeled unmanned aerial vehicle on a pipe, which is an emerging applica- tion in oil and gas facilities for nondestructive measurements. After the derivation of the dynamic model of the system, a discrete-time nonlinear model predictive controller is designed over a finite horizon. The analysis of the asymptotic stability of the designed controller is carried out. Numerical tests show the performance and the robustness of the proposed solution

    Curcumin-Loaded Mixed Micelles: Preparation, Characterization, and In Vitro

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    The objective of this study was to prepare curcumin-loaded mixed Soluplus/TPGS micelles (Cur-TPGS-PMs) for oral administration. The Cur-TPGS-PMs showed a mean size of 65.54 ± 2.57 nm, drug encapsulation efficiency over 85%, and drug loading of 8.17%. The Cur-TPGS-PMs were found to be stable in various pH media (pH 1.2 for 2 h, pH 6.8 for 2 h, and pH 7.4 for 6 h). The X-ray diffraction (XRD) patterns illustrated that curcumin was in the amorphous or molecular state within PMs. The In vitro release test indicated that Cur-TPGS-PMs possessed a significant sustained-release property. The cell viability in MCF-7 cells was found to be relatively lower in Cur-TPGS-PM-treated cells as compared to free Cur-treated cells. CLSM imaging revealed that mixed micelles were efficiently absorbed into the cytoplasm region of MCF-7 cells. Therefore, Cur-TPGS-PMs could have the significant value for the chronic breast cancer therapy

    Assessment of fetal left atrial volume and function using a novel left atrial volume tracking method

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    BACKGROUND: A number of fetal cardiovascular structural defects may alter the hemodynamics of the cardiac chambers resulting in changes in chamber sizes. Quantitative measurements of the sizes of cardiac chambers can augment the diagnostic power of fetal echocardiography. AIMS: Using a new left atrial volume tracking (LAVT) method, time-left atrial volume curves (TLAVCs) can be automatically obtained. The goal of this study was to examine whether this method can be used to evaluate left atrial volume (LAV) and provide reference values for LAV, and indices of left atrial function in normal human fetuses. METHODS: 204 normal human fetuses were enrolled. Using LAVT, the maximal left atrial volume (LAVmax) and minimal left atrial volume (LAVmin) were measured from TLAVCs. Left atrial ejection fraction (EF) was calculated. The maximal left atrial area (LAAmax) and minimal left atrial area (LAAmin) were measured using manual method tracing. RESULTS: From 21-40 weeks, mean LAVmax increased from 0.27 ml to 4.15 ml and mean LAVmin increased from 0.13ml to 2.26ml, respectively. While the EF remained stable at around 0.43. From 21-40 weeks, mean LAAmax increased from 0.61 cm2 to 2.64 cm2 and mean LAAmin increased from 0.34 cm2 to 1.53 cm2. CONCLUSIONS: This study establishes reference values for fetal LAV during the second half of gestation. LAVT method has proven to be a feasible method to estimate fetal LAV, suggesting the potential value in assessing left atrial function

    Programmed cell death and lipid metabolism of macrophages in NAFLD

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    Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored

    Suppression of Tumor Energy Supply by Liposomal Nanoparticle-Mediated Inhibition of Aerobic Glycolysis

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    Aerobic glycolysis enables cancer cells to rapidly take up nutrients (e.g., nucleotides, amino acids, and lipids) and incorporate them into the biomass needed to produce a new cell. In contrast to existing chemotherapy/radiotherapy strategies, inhibiting aerobic glycolysis to limit the adenosine 5′-triphosphate (ATP) yield is a highly efficient approach for suppressing tumor cell proliferation. However, most, if not all, current inhibitors of aerobic glycolysis cause significant adverse effects because of their nonspecific delivery and distribution to nondiseased organs, low bioavailability, and a narrow therapeutic window. New strategies to enhance the biosafety and efficacy of these inhibitors are needed for moving them into clinical applications. To address this need, we developed a liposomal nanocarrier functionalized with a well-validated tumor-targeting peptide to specifically deliver the aerobic glycolysis inhibitor 3-bromopyruvate (3-BP) into the tumor tissue. The nanoparticles effectively targeted tumors after systemic administration into tumor-bearing mice and suppressed tumor growth by locally releasing 3-BP to inhibit the ATP production of the tumor cells. No overt side effects were observed in the major organs. This report demonstrates the potential utility of the nanoparticle-enabled delivery of an aerobic glycolysis inhibitor as an anticancer therapeutic agent

    Degradability of Polymers for Implantable Biomedical Devices

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    Many key components of implantable medical devices are made from polymeric materials. The functions of these materials include structural support, electrical insulation, protection of other materials from the environment of the body, and biocompatibility, as well as other things such as delivery of a therapeutic drug. In such roles, the stability and integrity of the polymer, over what can be a very long period of time, is very important. For most of these functions, stability over time is desired, but in other cases, the opposite–the degradation and disappearance of the polymer over time is required. In either case, it is important to understand both the chemistry that can lead to the degradation of polymers as well as the kinetics that controls these reactions. Hydrolysis and oxidation are the two classes of reactions that lead to the breaking down of polymers. Both are discussed in detail in the context of the environmental factors that impact the utility of various polymers for medical device applications. Understanding the chemistry and kinetics allows prediction of stability as well as explanations for observations such as porosity and the unexpected behavior of polymeric composite materials in some situations. In the last part, physical degradation such interfacial delamination in composites is discussed

    Analyses of winter circulation types and their impacts on haze pollution in Beijing

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    To better understand the interannual variation of winter haze pollution, this paper investigates winter circulation types and their impacts on local meteorological conditions and haze pollution during 38 winters from 1980 to 2017 in Beijing. Circulation types were classified by T-mode principal component analysis combined with the K-means cluster method using European Centre for Medium-range Weather Forecasts ERA-interim sea level pressure data. The results can significantly distinguish the cold air process, a degeneration of cold air, and stagnant weather. The cold air process over Beijing was accompanied by a low temperature, high relative humidity, large pressure gradient and near-surface wind speed, and deep mixing layer. The cold air process facilitated pollutant dispersion and transport to the outside (such as East China, Bohai Sea, and Yellow Sea) and formed low PM2.5 concentrations and low frequencies of haze days. In contrast, the local meteorology and haze pollution were almost the inverse for stagnant weather. The local meteorological conditions and haze pollution for the degeneration of cold air are between the previous circulation types. Considering PM2.5 observation during 2010–2017, the occurrence frequency of cold air was low in the recent winters of 2013, 2014 and 2017, and resulted in severe PM2.5 pollution. High frequency of stagnant weather (48.4%) was one of the reasons that haze pollution reached 37% during 38 winters from 1980 to 2017 over Beijing. The time series of haze frequency was negatively correlated with that of cold air frequency. Winter haze pollution was affected by climate change over Beijing. During 38 winters from 1980 to 2017, a decreased trend of haze days was found, which was partly related to an increased trend of cold air frequency. However, the trends of haze days and cold air in Beijing were not significant based on regression analysis

    Specific Release of Bacteriochlorophylls B800 of LH2 from Rhodobacter azotoformans Induced by Sodium Dodecyl Sulfate

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    The release behaviors of bacteriochlorophylls of peripheral light-harvesting complex LH2 from Rhodobacter azotoformans induced by sodium dodecyl sulfate (SDS) were investigated using absorption spectroscopy. The results indicated that bacteriochlorophylls of B800 band are released from their binding sites and transformed into free bacteriochlorophylls by incubating LH2 sample in 10 mmol.L-1 Tris-HCl (pH 8.0) buffer containing SDS of low concentration at room temperature. However, the bacteriochlorophylls of B850 band are not released. The dynamics of B800 release and free BChl formation induced by 0.08% (w/V) SDS can be well fitted by the monoexponential model. The rate constant of B800 release is nearly equal to that of free BChls formation. The release of both B800 and B850 of LH2 can be induced by high concentration SDS, simultaneously. The bacteriochlorophylls of B800 band can be completely transformed into free BChls, but not for B850. Although both of their release processes show monoexponential models in 1% SDS solution, the release rate constant of B850 is remarkably lower than that of B800 and close to that of free BChls formation.国家自然科学基金(No. 30970068)、国家科技基础条件平台建设(No. 2005DKA21209)、厦门大学近海海洋环境科学国家重点实验室高级访问学者基 金(No. MELRS0907)和山西省回国留学人员科研(No. 200713)资助项目

    China's natural gas exploration and development strategies under the new normal

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    China's natural gas industry has experienced a great leap-forward development in the past decade. Since the second half of 2014, however, international oil price has dropped sharply and global oil and gas markets have been sluggish. In China, economy growth rate slows down and resource environments tend to be more restricted. And energy production and consumption revolution speed up, and the development of natural gas industry experience profound changes internally and externally. Through review on the achievements in recent high-speed development and analysis on the future development of China's natural gas industry, it is believed that the growth rates of China's natural gas output and consumption will slow down and the supply and demand fundamentals present loose states. Low-permeability tight, deep–extra deep and unconventional reservoirs will be the principal targets of natural gas exploration and development and the tendency of resource deterioration is inevitable. The pressure to the decrease of gas price rises due to the sustained recession of oil price and the sharp decrease of alternative energy price. The normal means to increase benefits is to control investment strictly and reduce cost greatly. As for the new normal, five suggestions are proposed for natural gas exploration and development in China. Firstly, reinforce exploration continuously by guaranteeing work load and investment at the required level, and tamp the development basis. Secondly, pay much attention to early development evaluation, give prominence to plan implementation design and control productivity construction rhythm. Thirdly, pay attention to the top-level design of mature gas field development and adjustment, with fine description and management as the priority, and improve overall development level. Fourthly, strengthen the researches on exploration and development technologies, with the simplification and practicability of technologies as the focus, and reduce the cost effectively. And fifthly, summarize high-speed development experience of natural gas industry, pay attention to the demonstration and design of key indicators, and strengthen the study on progressive planning
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