Results 1 - 10 of 1296
Results 1 - 10 of 1296. Search took: 0.027 seconds
|Sort by: date | relevance|
[en] Complex formation of indium(III) with three disubstituted pyridines, viz., 2,3-dihydroxypyridine, 2-amino-2-hydroxypyridine and 3-hydroxypyridine-2-thiol has been studied polarographically (μ=0.1; temp.=25+-0.10C). All the systems show reversible electrode behaviour. DeFord and Hume method as modified by Irving has been applied for determining composition and stability constants. Distribution of different species as a function of ligand concentration has been calculated and shown graphically. (author)
[en] How to identify influential nodes is still an open and vital issue in complex networks. To address this problem, a lot of centrality measures have been developed, however, only single measure is focused on by the existing studies, which has its own shortcomings. In this paper, a novel method is proposed to identify influential nodes using relative entropy and TOPSIS method, which combines the advantages of existing centrality measures. Because information flow spreads in different ways in different networks. In the specific network, the appropriate centrality measures should be considered to sort the nodes. In addition, the remoteness between the alternative and the positive/negetive ideal solution is redefined based on relative entropy, which is proven to be more effective in TOPSIS method. To demonstrate the effectiveness of the proposed method, four real networks are selected to conduct several experiments for identifying influential nodes, and the advantages of the method can be illustrated based on the experimental results.
[en] The Script Concordance test (SCT) is a reliable and valid tool to evaluate clinical reasoning in complex situations where experts' opinions may be divided. Scores reflect the degree of concordance between the performance of examinees and that of a reference panel of experienced physicians. The purpose of this study is to demonstrate SCT's usefulness in radiation oncology. A 90 items radiation oncology SCT was administered to 155 participants. Three levels of experience were tested: medical students (n = 70), radiation oncology residents (n = 38) and radiation oncologists (n = 47). Statistical tests were performed to assess reliability and to document validity. After item optimization, the test comprised 30 cases and 70 questions. Cronbach alpha was 0.90. Mean scores were 51.62 (± 8.19) for students, 71.20 (± 9.45) for residents and 76.67 (± 6.14) for radiation oncologists. The difference between the three groups was statistically significant when compared by the Kruskall-Wallis test (p < 0.001). The SCT is reliable and useful to discriminate among participants according to their level of experience in radiation oncology. It appears as a useful tool to document the progression of reasoning during residency training
[en] The deep involvement of glycans or carbohydrate moieties in biological processes makes glycan patterns an important direction for the clinical and medicine researches. A multiplexing CE mapping method for glycan analysis was developed in this study. By applying different CE separation mechanisms, the potential of combined parallel applications of capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC) and capillary gel electrophoresis (CGE) for rapid and accurate identification of glycan was investigated. The combination of CZE and MEKC demonstrated enhancing chromatography separation capacity without the compromises of sample pre-treatment and glycan concentration. The separation mechanisms for multiplexing platform were selected based on the orthogonalities of the separation of glycan standards. MEKC method exhibited promising ability for the analysis of small GU value glycans and thus complementing the unavailability of CZE. The method established required only small amount of samples, simple instrument and single fluorescent labelling for sensitive detection. This integrated method can be used to search important glycan patterns appearing in biopharmaceutical products and other glycoproteins with clinical importance. - Highlights: • Cross-validation of analytes in complex samples was done with different CE separation mechanisms. • A simple strategy is used to confirm peak identification and extend capacity of CE separation. • The method uses small amount of sample, simple instrument and single fluorescent labeling. • Selection of mechanisms is based on orthogonalities of GU values of glycan standards. • Micellar electrokinetic chromatography was suitable for analysis of small or highly sialylated glycans.
[en] The stability constants of methionine complexes of cadmium were determined polarographically by the method of DeFord and Hume as β1=6.5 x 103, β2=1.7 x 106 and β3=2.1 x 108. The indium complexes were studied by the modified method of Momoki and Ogawa and two complexes, with β1=1.7 x 108 and β2=8.4 x 1013, were identified in the concentration range studied. The half-wave potential of uncomplexed indium ion which cannot be measured directly owing to the irreversible nature of the reduction was calculated as -0.503 V vs. SCE. (author)
[en] A new strategy for sensitive fluorescence polarisation (FP) analysis is proposed which uses aptamer as the receptor and anchor protein modules as the enhancers by including the aptamers in complexes with protein modules. This approach is based on increasing the size differences of bound and unbound fluorophores. The strategy was applied in an ochratoxin A (ð×ðóðÉ) assay with the competitive binding of fluorophore-labelled and free OTA with aptamer-based receptors. We showed that the binding of labelled OTA with aptamer included in complexes with anchors led to higher a FP than binding with free aptamer. This allowed the aptamer concentration to be reduced, thus lowering the limit of detection by a factor of 40, down to 3.6 nM. The assay time was 15 min. To evaluate the applicability of the FP assay with aptamer–anchor complex to real samples, we conducted OTA measurements in spiked white wine. The OTA limit of detection in wine was 2.8 nM (1.1 μg/kg), and the recoveries ranged from 83% to 113%. The study shows that the proposed anchor strategy is efficient for increasing the sensitivity of FP-based aptamer assays. - Highlights: • Aptamer is anchored with proteins. • Anchored aptamer is used for fluorescence polarisation assay. • The use of anchors increases difference in polarisation of fluorescence. • Limit of detection for ochratoxin A is decreased 40 times by the anchor use.
[en] The crystal structure of the complex between the C-terminal domain of Streptococcus pyogenes β-NAD"+ glycohydrolase and an endogenous inhibitor for SPN was determined at 1.70 Å. It reveals that the interface between the two proteins is highly rich in water molecules. One of the virulence factors produced by Streptococcus pyogenes is β-NAD"+ glycohydrolase (SPN). S. pyogenes injects SPN into the cytosol of an infected host cell using the cytolysin-mediated translocation pathway. As SPN is toxic to bacterial cells themselves, S. pyogenes possesses the ifs gene that encodes an endogenous inhibitor for SPN (IFS). IFS is localized intracellularly and forms a complex with SPN. This intracellular complex must be dissociated during export through the cell envelope. To provide a structural basis for understanding the interactions between SPN and IFS, the complex was overexpressed between the mature SPN (residues 38–451) and the full-length IFS (residues 1–161), but it could not be crystallized. Therefore, limited proteolysis was used to isolate a crystallizable SPN_c_t–IFS complex, which consists of the SPN C-terminal domain (SPN_c_t; residues 193–451) and the full-length IFS. Its crystal structure has been determined by single anomalous diffraction and the model refined at 1.70 Å resolution. Interestingly, our high-resolution structure of the complex reveals that the interface between SPN_c_t and IFS is highly rich in water molecules and many of the interactions are water-mediated. The wet interface may facilitate the dissociation of the complex for translocation across the cell envelope