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81.
This study aims to reveal the laws of the relationship between fractional-order system and integer-order system. Meanwhile, delayed feedback control is introduced to control the fractional-order PMSG (permanent magnet synchronous generator) model of a wind turbine. First, the fractional-order mathematical model of PMSG is established. Next, numerical simulations under different system orders are given and the system dynamic behaviors are analyzed in detail. Then, the delayed feedback control method is introduced to control the fractional-order PMSG and the control results when different parameters vary are analyzed. Complex dynamics are presented and some interesting phenomena are discovered. It is found that the system order influences the dynamics of the system in many aspects such as chaos pattern, bifurcation behavior, period window, shape and size of strange attractor. The delayed time, feedback gain, feedback limitation, system order can obviously influence the control result except the initial state of the system. Moreover, the feedback limitation has a minimum to successfully control the system to stable states and the system order also has a maximum to do so. 相似文献
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83.
Abstract A two-stage process was developed for the living polymerization of isobutylene (IB) employing di-tert-alcohol initiators in conjunction with BCl3 coinitiator in the first or initiation stage, followed by TiCl4 coinitiator in the second or propagation stage; the process was shown to yield high molecular weight (up to M n 20,000), narrow molecular weight distribution (MWD) M w/M n = 1.1–1.2) di-tert-chlorine telechelic polyisobutylenes (tCl-PIB-Clt). The initiation stage involves the homogeneous solution living polymerization of IB induced by the di-tert-alcohol/BCl3 combination in the presence of an electron donor such as N,N-dimethylacetamide in CH3Cl solvent at ?80°C and proceeds up to M n < 5000; this is followed by the propagation stage in which TiCl4 and the bulk of IB plus a sufficient amount of n-C6H14 are added to the charge to bring the solvent composition to CH3Cl/n-C6H14 60/40 v/v and the living polymerization is continued until high M n product is obtained. This two-stage process was developed because 1) it employs very inexpensive chemicals; 2) di-tert-alcohol/BCl3 combinations initiate living IB polymerization in CH3Cl but the product after reaching M n ≤ 5000 precipitates out of the CH3Cl solution, and di-tert-alcohol/BCl4 combinations do not initiate IB polymerization; and 3) di-tert-alcohol/BCl3 systems do not initiate (or only very slowly) the living polymerization of IB in CH3Cl/n-C6H14 mixtures, whereas similar TiCl4-based systems do. The polymerization remains living during both stages although the propagating species and solvent polarity are profoundly altered. The livingness of the system has been analyzed by kinetic experiments and the structure of the tCl-PIB-Clt product by routine spectroscopic means. 相似文献
84.
Sang Mee Hwang Cha-ja See Jungeun Choi Seon Young Kim Qute Choi Jung Ah Kim Jiseok Kwon Si Nae Park Kyongok Im Il-Hoan Oh Dong Soon Lee 《Experimental & molecular medicine》2013,45(12):e68
The cytogenetic analysis of mesenchymal stromal cells (MSCs) is essential for verifying the safety and stability of MSCs. An in situ technique, which uses cells grown on coverslips for karyotyping and minimizes cell manipulation, is the standard protocol for the chromosome analysis of amniotic fluids. Therefore, we applied the in situ karyotyping technique in MSCs and compared the quality of metaphases and karyotyping results with classical G-banding and chromosomal abnormalities with fluorescence in situ hybridization (FISH). Human adipose- and umbilical cord-derived MSC cell lines (American Type Culture Collection PCS-500-011, PCS-500-010) were used for evaluation. The quality of metaphases was assessed by analyzing the chromosome numbers in each metaphase, the overlaps of chromosomes and the mean length of chromosome 1. FISH was performed in the interphase nuclei of MSCs for 6q, 7q and 17q abnormalities and for the enumeration of chromosomes via oligo-FISH in adipose-derived MSCs. The number of chromosomes in each metaphase was more variable in classical G-banding. The overlap of chromosomes and the mean length of chromosome 1 as observed via in situ karyotyping were comparable to those of classical G-banding (P=0.218 and 0.674, respectively). Classical G-banding and in situ karyotyping by two personnel showed normal karyotypes for both cell lines in five passages. No numerical or structural chromosomal abnormalities were found by the interphase-FISH. In situ karyotyping showed equivalent karyotype results, and the quality of the metaphases was not inferior to classical G-banding. Thus, in situ karyotyping with minimized cell manipulation and the use of less cells would be useful for karyotyping MSCs. 相似文献
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Buagafuran is a novel drug candidate derived from natural product.Its absolute configuration has been confirmed by electronic circular dichroism combined with modern quantum-chemical calculation using time-dependent density functional theory.The predicted UV absorbance peak is underestimated by several nanometers compared with the experimental data.The applicability of empirical rule for the C=C-C-O system in Buagafuran has also been discussed.Our results show that electronic circular dichroism could be a useful tool for the absolute configuration assignment of chiral drugs,especially for the oily or semisolid substances,whose crystal structures are impossible to obtain. 相似文献
88.
Hankun Zhou Si Chen Ning Gan Tianhua Li Yuting Cao Qianli Jiang 《Electroanalysis》2013,25(10):2384-2393
A novel sandwich‐type electrochemiluminescence (ECL) immunosensor was developed to enable the sensitive detection of HIV‐1 antibodies. This system incorporated mesoporous silica (mSiO2) complexed with quantum dots (QDs) and nano‐gold particles, which were assembled to enhance signal detection. Magnetic beads were used by immobilizing the secondary anti‐IgG antibody. This was first employed to capture HIV‐1 antibody (Ab) to form a Fe3O4/anti‐IgG/Ab complex. A high loading and signal‐enhanced nanocomposite (hereafter referred to as Au‐mSiO2‐CdTe) was used as a HIV‐1 antigen label. The Au‐mSiO2‐CdTe nanocomposite was conjugated with the Fe3O4/anti‐IgG/Ab complex to form an immunocomplex (hereafter referred to as Fe3O4/anti‐IgG/Ab/HIV‐1/CdTe‐mSiO2‐Au). This complex could be further separated by an external magnetic field to produce ECL signals. Due to the large specific surface area and pore volume of mSiO2, the loading of the CdTe QDs was markedly increased. Thus, the loaded QDs released a powerful chemiluminescent signal with a concordantly increased sensitivity of the immunosensor. The immunosensor was highly sensitive, and displayed a linear range of responses for HIV‐1 antibody across a dilution range of 1 : 1500 through 1 : 50 with the detection limit of 1 : 4500. The immunoassay can be a promising candidate in early diagnosis of HIV infection. 相似文献
89.
Yun-Yun Tang Hou-Yu Wang Lu Chen Si Li Chen-Gang Guo Hui-Zhi Fan Cheng-Xi Cao Liu-Yin Fan 《Analytical and bioanalytical chemistry》2013,405(26):8587-8595
We developed a novel polyacrylamide gel electrophoresis (PAGE) method to stack and separate human hemoglobins (Hbs) based on the concept of moving reaction boundary (MRB). This differs from the classic isotachophoresis (ITP)-based stacking PAGE in the aspect of buffer composition, including the electrode buffer (pH 8.62 Tris–Gly), sample buffer (pH 6.78 Tris–Gly), and separation buffer (pH 8.52 Tris–Gly). In the MRB-PAGE system, a transient MRB was formed between alkaline electrode buffer and acidic sample buffer, being designed to move toward the anode. Hbs carried partial positive charges in the sample buffer due to its pH below pI values of Hbs, resulting in electromigrating to the cathode. Hbs would carry negative charges quickly when migrated into the alkaline electrode buffer and be transported to the anode until meeting the sample buffer again. Thus, Hbs were stacked within a MRB until the transient MRB reached the separation buffer and then separated by zone electrophoresis with molecular sieve effect of the gel. The experimental results demonstrated that there were three clear and sharp protein zones of Hbs (HbA1c, HbA0, and HbA2) in MRB-PAGE, in contrast to only one protein zone (HbA0) in ITP-PAGE for large-volume loading (≥15 μl), indicating high stacking efficiency, separation resolution, and good sensitivity of MRB-PAGE. In addition, MRB-PAGE was performed in a conventional slab PAGE device, requiring no special device. Thus, it could be widely used in separation and analysis of diluted protein in a standard laboratory. Figure
Diagram of MRB-induced stacking in a slab PAGE. (A) arrangement of separation buffer (pH 8.01–9.55 Tris–Gly), sample buffer (pH 6.37–7.22 Tris–Gly), and electrode buffer (pH 8.21–9.05 Tris–Gly); (B) initial MRB formed between electrode and sample buffers for stacking of low-content Hbs in sample buffer under electric field; (C) MRB moving toward the anode and partly stacking of Hbs within the MRB; (D) quasi-complete stacking of Hbs via MRB closing to the separating gel; (E) separation of Hbs in a zone electrophoresis mode 相似文献
90.
A new bridging ligand, 2,3‐di(2‐pyridyl)‐5‐phenylpyrazine (dpppzH), has been synthesized. This ligand was designed so that it could bind two metals through a NN‐CNN‐type coordination mode. The reaction of dpppzH with cis‐[(bpy)2RuCl2] (bpy=2,2′‐bipyridine) affords monoruthenium complex [(bpy)2Ru(dpppzH)]2+ ( 12+ ) in 64 % yield, in which dpppzH behaves as a NN bidentate ligand. The asymmetric biruthenium complex [(bpy)2Ru(dpppz)Ru(Mebip)]3+ ( 23+ ) was prepared from complex 12+ and [(Mebip)RuCl3] (Mebip=bis(N‐methylbenzimidazolyl)pyridine), in which one hydrogen atom on the phenyl ring of dpppzH is lost and the bridging ligand binds to the second ruthenium atom in a CNN tridentate fashion. In addition, the RuPt heterobimetallic complex [(bpy)2Ru(dpppz)Pt(C?CPh)]2+ ( 42+ ) has been prepared from complex 12+ , in which the bridging ligand binds to the platinum atom through a CNN binding mode. The electronic properties of these complexes have been probed by using electrochemical and spectroscopic techniques and studied by theoretical calculations. Complex 12+ is emissive at room temperature, with an emission λmax=695 nm. No emission was detected for complex 23+ at room temperature in MeCN, whereas complex 42+ displayed an emission at about 750 nm. The emission properties of these complexes are compared to those of previously reported Ru and RuPt bimetallic complexes with a related ligand, 2,3‐di(2‐pyridyl)‐5,6‐diphenylpyrazine. 相似文献