The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
M. Simeonova - One of the best experts on this subject based on the ideXlab platform.
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Study on the effect of polybutyl-2-cyanoacrylate nanoparticles and their metabolites on the phagocytic activity of peritoneal exudate cells of mice.
Biomaterials, 2003Co-Authors: M. Simeonova, M Antcheva, K. ChorbadjievAbstract:The phagocytic activity of peritoneal exudate cells (PECs) harvested from peritoneal cavity of mice after a single intraperitoneal (i.p.) treatment with poly(butylcyanoacrylate) nanoparticles (Pbcn) and their probable metabolites [poly(cyanoacrylic acid) (PCAA) and n-butanol] was investigated in an in vitro phagocytic assay. Polymer suspension of Pbcn was given as a single i.p. injection at doses of 200 and 10 mgkg(-1), 3, 18, 72 and 120 h before the performance of the phagocytic assay. PCAA and n-butanol were given at the same manner at doses of 126.8 and 96.8 mgkg(-1), respectively (equivalent to a dose of 200 mgkg(-1) of intact Pbcn after enzyme hydrolysis) 3, 18 and 120 h before the test performance. The phagocytic assay was performed in vitro in tubes with sheep red blood cells (SRBC). Phagocytic index (percentage of PECs ingested more than 3 sheep erythrocytes), phagocytic number, and ingestion capacity (number of erythrocytes ingested per cell) were the parameters used for evaluation of the phagocytic activity. The alterations of phagocytic activity of the PECs observed were strongly time- and dose-dependent. Administration of all tested compounds shortly before the test performance resulted in a considerable decrease in the capability of PECs to ingest SRBC. The alterations of phagocytic activity decreased when the time between the treatment of mice and the phagocytic assay is on the increase. The dose of 200 mgkg(-1) of Pbcn administered 120 h before the phagocytic assay led to the significant increase of the phagocytic index of PECs. The phagocytic function of assayed PECs was temporary impeded and 5 days were completely enough for their restoration.
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Study of the effect of polybutylcyanoacrylate nanoparticles and their metabolites on the primary immune response in mice to sheep red blood cells
Biomaterials, 1998Co-Authors: M. Simeonova, K. Chorbadjiev, M AntchevaAbstract:Abstract Polybutylcyanoacrylate nanoparticles (Pbcn) and their metabolites (polycyanoacrylic acid—PCAA, and n -butanol) were compared with respect to their effects on the primary immune response of mice to sheep red blood cells (SRBC). PCAA was synthetized via a Knoevenagel reaction. Antibody production (hemagglutinins) and E-rosette-forming cells (E-RFC) were used to document the induction of antigen-specific immune response to SRBC in all immunized mice. Pbcn showed a time- and dose-dependent effect on the immune response, both humoral and cellular. The inductive phase of immune response was affected preferably. The high dose of Pbcn (200 mg kg -1 ) tended to suppress the immune response. This was expressed more in mice treated before antigenic stimulation. Lower dose (10 mg kg -1 ) stimulated the immune response. A significant difference was found in the effects of Pbcn and their metabolites on the immune response. PCAA and n -butanol administered at doses equivalent (after lysosomal hydrolysis) to the doses applied of intact Pbcn did not impair significantly the immune response. A clear time dependence and dose dependence were not observed. The study led to the hypothesis that the greater suppressive effect of Pbcn, relative to either PCAA or n -butanol, or a mixture of them, is probably due to the blocking of the immunopresenting function of macrophages instead of some toxicity towards the immunocompetent cells.
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Effect of polybutylcyano acrylate nanoparticles on primary immune response of mice to sheep erythrocytes
International Journal of Pharmaceutics, 1994Co-Authors: M. Atcheva, M. Simeonova, M. Boeva, C. KonstantinovAbstract:Abstract The effect of polybutylcyanoacrylate nanoparticles (Pbcn) on the primary immune response of mice to sheep erythrocytes (SRBC) was studied by estimating antibody production (hemagglutinins) and rosette-forming cells (E-RFC). The data obtained indicated that the ability of treated mice to establish a specific immune response was markedly impaired when Pbcn were administered at high doses prior to antigenic stimulation. The degree of depression was dose-dependent. When Pbcn were injected after immunization or on the day of immunization with SRBC, there were no significant differences with the control. Small doses of Pbcn given before immunization or shortly thereafter stimulated the primary immune response to SRBC. These data revealed that the inductive phase of primary immune response had been affected preferably by Pbcn. The conclusion might be drawn that the specific immune response induced in animals before treatment with Pbcn would not be affected by nanoparticles and that they could be used as a drug carrier in chemotherapy.
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In vitro study of cytotoxic activity of vinblastine in a free form and associated with nanoparticles.
Acta physiologica et pharmacologica Bulgarica, 1994Co-Authors: M. Simeonova, M AntchevaAbstract:The cytotoxic activities of unloaded polybutylcyanoacrylate nanoparticles (Pbcn), free vinblastine, vinblastine-loaded nanoparticles (by incorporation and adsorption processes) and a mixture of vinblastine-free and unloaded Pbcn were compared in vitro on human erythroleukemic K-562 cells. Enhanced cytotoxicity was observed when vinblastine was either adsorbed on Pbcn or mixed with them rather than free. When vinblastine was incorporated into polymer matrix of nanoparticles, a lag period and postponed cytotoxic effect on K-562 cells were observed.
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Tissue distribution of polybutylcyanoacrylate nanoparticles loaded with spin-labelled nitrosourea in Lewis lung carcinoma-bearing mice.
Acta physiologica et pharmacologica Bulgarica, 1994Co-Authors: M. Simeonova, T. Ivanova, Z. Raikov, Konstantinov HAbstract:The tissue distribution of polybutylcyanoacrylate nanoparticles (Pbcn) with a diameter of 127 nm, loaded with 1-(2-chloroethyl)-3-(1-oxyl-2,2,6,6-tetramethylpiperidinyl)-1- nitrosourea (spin-labelled nitrosourea, SLCNU) is described. Pbcn-suspensions were intraperitoneally (i.p.) injected into Lewis lung carcinoma bearing mice. The biodistribution of Pbcn in the visceral organs, blood and tumor was studied by electron spin resonance (ESR) spectroscopy. A relatively low accumulation of nanoparticles in the liver and spleen was found. The accumulation was negligible in the i.m. implanted primary tumor. SLCNU-loaded nanoparticles were mainly found in the lungs, kidneys, and heart. The highest content of the particles studied was observed in the lungs of tumor bearing experimental animals damaged by metastases. These findings suggest that Pbcn offer some opportunities in the targeting of SLCNU to lung metastases.
Weihua Gui - One of the best experts on this subject based on the ideXlab platform.
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Asymptotical Feedback Set Stabilization of Probabilistic Boolean Control Networks
IEEE transactions on neural networks and learning systems, 2020Co-Authors: Rongpei Zhou, Yuqian Guo, Weihua GuiAbstract:In this article, we investigate the asymptotical feedback set stabilization in distribution of probabilistic Boolean control networks (Pbcns). We prove that a Pbcn is asymptotically feedback stabilizable to a given subset if and only if (iff) it constitutes asymptotically feedback stabilizable to the largest control-invariant subset (LCIS) contained in this subset. We proposed an algorithm to calculate the LCIS contained in any given subset with the necessary and sufficient condition for asymptotical set stabilizability in terms of obtaining the reachability matrix. In addition, we propose a method to design stabilizing feedback based on a state-space partition. Finally, the results were applied to solve asymptotical feedback output tracking and asymptotical feedback synchronization of Pbcns. Examples were detailed to demonstrate the feasibility of the proposed method and results.
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Sampled-Data State-Feedback Stabilization of Probabilistic Boolean Control Networks: A Control Lyapunov Function Approach
IEEE transactions on cybernetics, 2019Co-Authors: Jiayang Liu, Yuqian Guo, Yang Liu, Weihua GuiAbstract:This article investigates the partial stabilization problem of probabilistic Boolean control networks (Pbcns) under sample-data state-feedback control (SDSFC) with a control Lyapunov function (CLF) approach. First, the probability structure matrix of the considered Pbcn is represented by a Boolean matrix, based on which, a new algebraic form of the system is obtained. Second, we convert the partial stabilization problem of Pbcns into the global set stabilization one. Third, we define CLF and its structural matrix under SDSFC. It is found that the existence of a CLF is equivalent to that of SDSFC. Then, a necessary and sufficient condition is obtained for the existence of CLF under SDSFC, based on which, all possible sample-data state-feedback controllers and corresponding structural matrices of CLF are designed by two different methods. Finally, examples are given to illustrate the efficiency of the obtained results.
Yuqian Guo - One of the best experts on this subject based on the ideXlab platform.
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Asymptotical Feedback Set Stabilization of Probabilistic Boolean Control Networks
IEEE transactions on neural networks and learning systems, 2020Co-Authors: Rongpei Zhou, Yuqian Guo, Weihua GuiAbstract:In this article, we investigate the asymptotical feedback set stabilization in distribution of probabilistic Boolean control networks (Pbcns). We prove that a Pbcn is asymptotically feedback stabilizable to a given subset if and only if (iff) it constitutes asymptotically feedback stabilizable to the largest control-invariant subset (LCIS) contained in this subset. We proposed an algorithm to calculate the LCIS contained in any given subset with the necessary and sufficient condition for asymptotical set stabilizability in terms of obtaining the reachability matrix. In addition, we propose a method to design stabilizing feedback based on a state-space partition. Finally, the results were applied to solve asymptotical feedback output tracking and asymptotical feedback synchronization of Pbcns. Examples were detailed to demonstrate the feasibility of the proposed method and results.
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Sampled-Data State-Feedback Stabilization of Probabilistic Boolean Control Networks: A Control Lyapunov Function Approach
IEEE transactions on cybernetics, 2019Co-Authors: Jiayang Liu, Yuqian Guo, Yang Liu, Weihua GuiAbstract:This article investigates the partial stabilization problem of probabilistic Boolean control networks (Pbcns) under sample-data state-feedback control (SDSFC) with a control Lyapunov function (CLF) approach. First, the probability structure matrix of the considered Pbcn is represented by a Boolean matrix, based on which, a new algebraic form of the system is obtained. Second, we convert the partial stabilization problem of Pbcns into the global set stabilization one. Third, we define CLF and its structural matrix under SDSFC. It is found that the existence of a CLF is equivalent to that of SDSFC. Then, a necessary and sufficient condition is obtained for the existence of CLF under SDSFC, based on which, all possible sample-data state-feedback controllers and corresponding structural matrices of CLF are designed by two different methods. Finally, examples are given to illustrate the efficiency of the obtained results.
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Set Stabilization in Distribution of Probabilistic Boolean Control Networks
2018 13th World Congress on Intelligent Control and Automation (WCICA), 2018Co-Authors: Rongpei Zhou, Yuqian GuoAbstract:In this paper, we propose the concept of set stabilization in distribution of a probabilistic Boolean control network (Pbcn), which determines whether the probability distribution converges to the distribution of the destination state subset under a certain control sequence. Then an algorithm is proposed to calculate the largest control invariant subset (LCIS) of a Pbcn contained in a given set. We prove that for a Pbcn, set stabilizability in distribution and set stabilizability in distribution by state feedback are equivalent. Based on this, a necessary and sufficient condition for set stabilizability in distribution is derived, and a control design method is proposed. Finally, examples are provided to illustrate the effectiveness of the proposed method.
Zichao Tang - One of the best experts on this subject based on the ideXlab platform.
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Structures and properties the lead-doped carbon clusters Pbcn/Pbcn+/Pbcn- (n=1-10)
The Journal of Chemical Physics, 2003Co-Authors: Xiaopeng Xing, Zichao TangAbstract:A systemic density functional theory study of the lead-doped carbon clusters Pbcn/Pbcn+/Pbcn- (n=1-10) has been carried out using B3LYP method with both CEP-31G and TZP+ basis sets. For each species, the electronic states, relative energies and geometries of various isomers are reported. According to these calculations, the Pb-terminated linear or quasilinear isomer is the most stable structure for Pbcn/Pbcn+/Pbcn- clusters except for PbC2/PbC2+ and PbC10/PbC10+. Both PbC2 and PbC2+ have bent ground state structure. For neutral PbC10, the global minimum possesses a Pb-containing 11-membered ring structure, while for cationic PbC10+, the Pb-side-on C-10 monocyclic configuration has lowest energy. Except for the smallest PbC, PbC+, and PbC-, the electronic ground state is alternate between (3)Sigma (for n-odd member) and (1)Sigma (for the n-even member) for linear Pbcn and invariably (2)Pi for linear Pbcn+ and Pbcn-. The incremental binding energy diagrams show that strong even-odd alternations in the cluster stability exist for both neutral Pbcn and anionic Pbcn-, with their n-even members being much more stable than the corresponding odd n-1 and n+1 ones, while for cationic Pbcn+, the alternation effect is less pronounced. These parity effects also reflect in the ionization potential and electron affinity curves. The even-odd alternation predicted by theoretical studies for anionic Pbcn- is in good agreement with the even-odd alternation mass distribution observed in the time-of-flight mass spectra. By comparing with the fragmentation energies accompanying various channels, the most favorable dissociation channel for each kind of the Pbcn/Pbcn+/Pbcn- clusters are given. (C) 2003 American Institute of Physics.
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structures and properties the lead doped carbon clusters Pbcn Pbcn Pbcn n 1 10
Journal of Chemical Physics, 2003Co-Authors: Xiaopeng Xing, Zichao TangAbstract:A systemic density functional theory study of the lead-doped carbon clusters Pbcn/Pbcn+/Pbcn- (n=1-10) has been carried out using B3LYP method with both CEP-31G and TZP+ basis sets. For each species, the electronic states, relative energies and geometries of various isomers are reported. According to these calculations, the Pb-terminated linear or quasilinear isomer is the most stable structure for Pbcn/Pbcn+/Pbcn- clusters except for PbC2/PbC2+ and PbC10/PbC10+. Both PbC2 and PbC2+ have bent ground state structure. For neutral PbC10, the global minimum possesses a Pb-containing 11-membered ring structure, while for cationic PbC10+, the Pb-side-on C-10 monocyclic configuration has lowest energy. Except for the smallest PbC, PbC+, and PbC-, the electronic ground state is alternate between (3)Sigma (for n-odd member) and (1)Sigma (for the n-even member) for linear Pbcn and invariably (2)Pi for linear Pbcn+ and Pbcn-. The incremental binding energy diagrams show that strong even-odd alternations in the cluster stability exist for both neutral Pbcn and anionic Pbcn-, with their n-even members being much more stable than the corresponding odd n-1 and n+1 ones, while for cationic Pbcn+, the alternation effect is less pronounced. These parity effects also reflect in the ionization potential and electron affinity curves. The even-odd alternation predicted by theoretical studies for anionic Pbcn- is in good agreement with the even-odd alternation mass distribution observed in the time-of-flight mass spectra. By comparing with the fragmentation energies accompanying various channels, the most favorable dissociation channel for each kind of the Pbcn/Pbcn+/Pbcn- clusters are given. (C) 2003 American Institute of Physics.
Christopher L. Cahill - One of the best experts on this subject based on the ideXlab platform.
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Exploring lanthanide luminescence in metal-organic frameworks: synthesis, structure, and guest-sensitized luminescence of a mixed europium/terbium-adipate framework and a terbium-adipate framework.
Inorganic chemistry, 2007Co-Authors: Daniel T. De Lill, § And Ana De Bettencourt-dias, Christopher L. CahillAbstract:Two lanthanide-organic frameworks were synthesized via hydrothermal methods. Compound 1 ([(Eu,Tb)(C6H8O4)3(H2O)2].(C10H8N2), orthorhombic, Pbcn, a = 21.925(2) A, b = 7.6493(7) A, c = 19.6691(15) A, alpha = beta = gamma = 90 degrees, Z = 4) takes advantage of the similar ionic radii of the lanthanide elements to induce a mixed-lanthanide composition. Compound 2 ([Tb2(C6H8O4)3(H2O)2].(C10H8N2), orthorhombic, Pbcn, a = 21.866(3) A, b = 7.6101(10) A, c = 19.646(3) A, alpha = beta = gamma = 90 degrees, Z = 8) is the terbium-only analogue of compound 1. Solid-state measurements of their luminescence behavior demonstrate that the neutral guest molecule (4,4'-dipyridyl) residing in the extraframework channels is successful in sensitizing lanthanide ion emission. In compound 1, columinescence occurs, and both lanthanide ions show emission. Additionally, quantum yield and lifetime measurements support the premise that the Tb3+ center is also acting to sensitize the Eu3+, effectively enhancing Eu3+ emission.
