50 research outputs found

    Effect of berbamine hydrochloride on the absorption of berberine hydrochloride in an in situ single-pass intestinal perfusion system in rats

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    Purpose: To investigate the intestinal absorption characteristics of berberine hydrochloride (BBH) under different perfusion conditions in rats.Methods: Based on the in situ single-pass intestinal perfusion model of rats, HPLC was used to determine the content of berberine hydrochloride in solution after perfusion under different conditions. The absorption rate constant (Ka), effective permeability coefficient (Papp) and cumulative absorption per unit area (Q) under different perfusion conditions were analyzed by one-way ANOVA.Results: The Papp and Ka of BBH in perfusion solution at pH 7.4 were greater than those in perfusion solution at pH 6 and 8. There was no significant difference (p > 0.05) in Papp and Ka of duodenum, jejunum and ileum at high, medium and low concentrations of berberine hydrochloride perfusion solution. The Q increased linearly with increase of mass concentration of perfusion solution. The Ka and Papp of BBH in duodenum, jejunum, and ileum of BBH and berbamine hydrochloride (BAH) combined at different ratios were higher than those of BBH control group at the same BBH concentration, but absorption of BBH in the ratio B40:A50 and B30:A20 groups was highest. In the ratio of B40:A50 ratio, B30:A20 ratio group or the same concentration's BBH group, Ka and Papp of BBH decreased in the order of jejunum > duodenum > ileum.Conclusion: Berberine hydrochloride is absorbed in neutral environment of pH 7.4. The intestinal absorption mechanism of BBH is passive diffusion, and jejunum is the best intestinal segment for absorption. BAH promotes the absorption of BBH

    Molecular and morphological evidence support a new species of Rosaceae Prunus subg. Cerasus from Wuyishan National Park, southeast China

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    Prunus tongmuensis, a new species of cherry blossom, is described and illustrated from Wuyishan National Park, southeast China. This species is characterized by its tubular to nearly bottle-shaped receptacles and dark purple drupes. It can be distinguished from other wild cherry trees by its flowers and leaves, reddish brown young leaves, presence of 1–2 glands at the base of leaves, petioles densely covered with yellowish brown villi, longer pedicels (0.6–2.5 cm), villous pistil, and dark purple drupes. In the present study, we conducted a comprehensive morphological study based on specimens of the new species and its morphologically close species, field observations, and examination of pollen morphology. In addition, our phylogenetic analysis based on the complete plastid genome sequences further confirms the status of the new species and indicates that it is closely related to Prunus clarofolia, however, it notably differs in leaf shape, size, petiole villus color, gland location, timing of flower and leaf openings, and reflexed or spread sepals, as well as drupe color

    Greedy Algorithm-Based Track-Before-Detect in Radar Systems

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    Joint Optimization of Receiver Placement and Illuminator Selection for a Multiband Passive Radar Network

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    The performance of a passive radar network can be greatly improved by an optimal radar network structure. Generally, radar network structure optimization consists of two aspects, namely the placement of receivers in suitable places and selection of appropriate illuminators. The present study investigates issues concerning the joint optimization of receiver placement and illuminator selection for a passive radar network. Firstly, the required radar cross section (RCS) for target detection is chosen as the performance metric, and the joint optimization model boils down to the partition p-center problem (PPCP). The PPCP is then solved by a proposed bisection algorithm. The key of the bisection algorithm lies in solving the partition set covering problem (PSCP), which can be solved by a hybrid algorithm developed by coupling the convex optimization with the greedy dropping algorithm. In the end, the performance of the proposed algorithm is validated via numerical simulations

    Inter-frame Ambiguity Analysis and Suppression of LTE Signal for Passive Radar

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    Long Term Evolution (LTE) is a new type of illuminators of opportunity for passive radars, with the advantages of broad bandwidth, high coverage, and strong generality. In this paper, the ambiguity function of Frequency Division Duplexing Long Term Evolution (FDD-LTE) signal is analyzed as an illuminator of opportunity. According to the measured signal, it was found that it is necessary to suppress the inter-frame ambiguity strips in the ambiguity function. Furthermore, themechanism of these inter-frame ambiguity strips was analyzed in detail, which revealed that the LTE signal frame structure is the main factor that causes these inter-frame ambiguity strips and is the major energy source of coherent integration. Thus, a method based on Orthogonal Frequency Division Multiplexing (OFDM) symbol subcarrier coefficient normalization is proposed to suppress these inter-frame ambiguity strips. Simulation and experimental results show that the method can suppress inter-frame ambiguity strips effectively, but does not affect coherent integration, which is the foundation of target detection

    Range-Angle Dependent Beampattern Synthesis Method for OFDM-Based Passive Radar

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    Frequency diverse array (FDA) radar applies a tiny frequency offset across its adjacent transmitting array elements to generate a range-angle-dependent beampattern. The increased degrees-of-freedom (DOFs) in range domain can help improve the performance of radar in target detection, localization, and clutter suppression. Passive radar utilizes uncontrollable external signal as illuminator, which makes it difficult to apply traditional frequency diverse process method. However, the third-party illuminator such as Orthogonal Frequency Division Multiplexing (OFDM) signal usually consists of several closely spaced modulated carriers, and it has been widely selected as the illuminator for passive radar in recent years. Considering the orthogonality between even separated subcarriers, we propose a new frequency diverse process method by extracting and processing each subcarrier of received data independently and attempt to provide a range-angle dependent beampattern for OFDM passive radar. Numerical results and real data analyses verify the superiority of frequency diversity process on the received data of OFDM passive radar

    The complete chloroplast genome of Changnienia amoena S. S. Chien (Orchidaceae) and its phylogenetic implication

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    Changnienia amoena S. S. Chien is mainly distributed in the mid-subtropical hilly areas of central and eastern China at an altitude of 200–1700 m. It has important academic significance in the orchid phylogeny, and is an excellent wild flower and precious medicinal plant. The species was once abundant but has become rare and endangered in recent years and has been identified as Endangered (EN) under criteria A2c (The IUCN Red List and Threatened Specis) because of the habitat fragmentation and unduly commercial collections. In this study, the complete chloroplast (cp) genome sequence of C. amoena was determined using next-generation sequencing. The entire cp genome was determined to be 156,818 bp in length. It contained large single-copy (LSC) and small single-copy (SSC) regions of 84,847 and 18,141bp, respectively, which were separated by a pair of 26,915 bp inverted repeat (IR) regions. The genome contained 133 genes, including 87 protein-coding genes, 38 tRNA genes, and eight rRNA genes.The overall GC content of the genome is 37.1%. A phylogenetic tree reconstructed by 48 chloroplast single-copy coding gene reveals that C. amoena is closely related with Calypso bulbosa

    An automated framework for NMR resonance assignment through simultaneous slice picking and spin system forming

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    Despite significant advances in automated nuclear magnetic resonance-based protein structure determination, the high numbers of false positives and false negatives among the peaks selected by fully automated methods remain a problem. These false positives and negatives impair the performance of resonance assignment methods. One of the main reasons for this problem is that the computational research community often considers peak picking and resonance assignment to be two separate problems, whereas spectroscopists use expert knowledge to pick peaks and assign their resonances at the same time. We propose a novel framework that simultaneously conducts slice picking and spin system forming, an essential step in resonance assignment. Our framework then employs a genetic algorithm, directed by both connectivity information and amino acid typing information from the spin systems, to assign the spin systems to residues. The inputs to our framework can be as few as two commonly used spectra, i.e., CBCA(CO)NH and HNCACB. Different from the existing peak picking and resonance assignment methods that treat peaks as the units, our method is based on 'slices', which are one-dimensional vectors in three-dimensional spectra that correspond to certain () values. Experimental results on both benchmark simulated data sets and four real protein data sets demonstrate that our method significantly outperforms the state-of-the-art methods while using a less number of spectra than those methods. Our method is freely available at http://sfb.kaust.edu.sa/Pages/Software.aspx
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