This paper proposes a character segmentation and spotting method of historical documents. In the segmentation method, the result of character recognition process is utilized to cope with the cursive scripts and the mutual encroachment of characters which are peculiar to the historical documents. In the spotting method, the previously designated characters are only extracted from the characters string. As an early segmentation, the characters string pattern is divided into the same connected component by using the labelling processing. The area composed of the same component is surrounded with a rectangle and each character pattern is segmented each other by using the shape of rectangle such as height and width. Next, the individual character recognition is applied to the segmented pattern. From the recognition result, the rectangle failed in the segmentation is picked up and the resegmentation is applied to the string contains this rectangle. Therefore, it is expected that the string is divided at the best position. On the other hand the neural network which corresponds to the previously designated character is prepared. The error between input and output of the network applied to the segmented pattern is calculated and the pattern which satisfies the condition is extracted as a spotting result. From the extraction experiment applied to 615 characters strings, the correct spotting rate of 94.22% was obtained to 5 designated characters by using the resegmentation process, but the rate was 87.58% without the resegmentation process.
Weakly bound reactant and product complexes in the hydrogen abstraction reactions of an OH radical with CH4, C2H6, and C3H8 are investigated with ab initio molecular orbital methods. The calculated binding energy of the CH4 and OH reactant complex at CCSD(T)/aug-cc-pVTZ (aug-cc-pVDZ) levels is 0.54 (0.74) kcal/mol. The zero-point vibrational energy correction at MP2 level with the corresponding basis sets reduces the binding energy to 0.16 (0.08) kcal/mol, which is substantially smaller than the recent experimental estimation (about 0.60 kcal/mol). A product complex for the CH4 + OH system, which is more stable than the reactant complex, has the binding energy of 0.77 (0.79) kcal/mol at CCSD(T)/aug-cc-pVTZ (aug-cc-pVDZ) levels with MP2 zero-point energy corrections. The reactant and product complexes are also found for the C2H6 + OH and C3H8 + OH reactions at the CCSD(T)/aug-cc-pVDZ level of theory. The binding energies tend to increase with the number of carbon atoms of the hydrocarbon. The reaction rates and their temperature dependence are estimated, and they are more than 1 order of magnitude larger than the experimentally reported values.
In the winter of 1989 and the spring of 1990, there were large outbreaks of respiratory disease in two swine herds in Nagasaki Prefecture, southern Japan. Serological surveillance indicated that the majority of swine possessed antibodies to swine influenza virus H1 haemagglutinin and neuraminidase of early H3N2 influenza virus strains. Eight viruses were isolated from swine that showed typical clinical symptoms of influenza. The haemagglutinin and neuraminidase of these isolates were closely related to those of swine H1N1 and early human H3N2 viruses, respectively. At least two types of haemagglutinin antigens, distinguished by two monoclonal antibodies, were involved in the outbreaks. Evolutionary analyses indicated that the haemagglutinin gene of the H1N2 reassortants was closely related to those of a recent swine lineage (A/sw/HK/1/74 and A/sw/Ehime/1/80 viruses). However, the neuraminidase genes of the H1N2 reassortants were similar to those of swine N2 viruses which in turn are related to early human H3N2 viruses. A comparison of partial nucleotide sequences revealed that the six other genes of A/sw/Nagasaki/1/89 were derived from those of swine H1N1 virus.
The serum mannan-binding protein (MBP) is a host defense C-type lectin specific for mannose, N-acetylglucosamine, and fucose residues, and exhibits growth inhibitory activity toward human colorectal carcinoma cells. The MBP-ligand oligosaccharides (MLO) isolated from a human colorectal carcinoma cell line, SW1116, are large, multiantennary N-glycans with highly fucosylated polylactosamine-type structures having Leb–Lea or tandem repeats of the Lea structure at their nonreducing ends. In this study, we isolated the major MBP-ligand glycoproteins from SW1116 cell lysates with an MBP column and identified them as CD26/dipeptidyl peptidase IV (DPPIV) (110 kDa) and CD98 heavy chain (CD98hc)/4F2hc (82 kDa). Glycosidase digestion revealed that CD26 contained such complex-type N-glycans that appear to mediate the MBP binding. MALDI-MS of the N-glycans released from CD26 by PNGase F demonstrated conclusively that CD26 is the major MLO-carrying protein. More interestingly, a comparison of the N-glycans released from the MBP-binding and non-MBP-binding glycopeptides suggested that complex-type N-glycans carrying a minimum of 4 Lea/Leb epitopes arranged either as multimeric tandem repeats or terminal epitopes on multiantennary structures are critically important for the high affinity binding to MBP. Analysis of the N-glycan attachment sites demonstrated that the high affinity MLO was expressed preferentially at some N-glycosylation sites, but this site preference was not so stringent. Finally, hypothetical 3D models of tandem repeats of the Lea epitope and the MBP-Lewis oligosaccharide complex were presented.
The multireference Møller−Plesset perturbation (MRMP) theory with complete active space self-consistent field (CASSCF) reference functions is applied to the study of the Q and B bands of free-base, magnesium, and zinc porphyrins and their derivatives. The Q band of free-base porphyrin is so weak because the transition is pseudoparity-forbidden because of the alternancy symmetry. The Q band in the visible region can be intensified if the pairing property is broken. This is achieved by various chemical modifications to the basic structure of free-base porphyrin such as external substituents, changes in conjugation pathway, and change in central substituent. The intensity and color of the Q band as well as the macrocyclic porphyrin skeleton are perturbed to a greater or lesser extent by various chemical modifications. Insertion of aza groups in meso position leads to the shrinking of the size of the central hole, whereas hydrogenation to the exo double bond of pyrrole rings expands the central hole. Substitution of nitrogen atoms for meso carbon atoms significantly intensifies the oscillator strength of the higher energy side transition of the Q band with the peak position unchanged. Ring reduction widens the splitting of two peaks of the Q band, giving rise to the characteristically strong far-red band and the weaker visible band. Changes from metal-free to metalloporphyrins have a less dramatic effect on the spectra.
In structural biology, molecular simulations have played an important role in elucidating functions of the biological system. The understanding of biological phenomena at the molecular level is expected to lead the modeling of disease, drug discovery, and various applications. A variety of life phenomena occur through the combination of site-specific molecular recognition of biomacromolecules. Computer simulations thus provide a promising approach to elucidate these molecular interactions in detail. However, most calculations carried out to date have employed classical mechanical methods based on empirical force fields. Such methods remain limited for performing an accurate analysis of intermolecular interactions such as charge redistribution and charge-transfer (CT) interactions. In contrast to the limitations of classical approaches to molecular simulation, quantum mechanical simulations have been used to successfully characterize weak intermolecular interactions and CT processes. Because several different types of interactions are involved in the interactions of biomolecules, quantum mechanical treatment is necessary to obtain an accurate and systematic understanding of these interactions. The fragment molecular orbital (FMO) method1-4 is one of the most reasonable tools with which to analyze the electronic structure of biomacromolecules.
The stable structures of α‐N‐acetyl‐D‐neuraminic acid (Neu5Acα) in the gas phase were studied at the B3LYP level of theory using 6‐31G(d,p) and 6‐31++G(d,p) basis sets. They are classified into five types according to the patterns of the intramolecular hydrogen bond formations. One of the stable structures had intramolecular hydrogen bond network of O9HO9 … O8HO8 … O˭C1‐O1HO1 and O7HO7…O˭CHN‐C5 similar to the crystal structure of Neu5Ac‐α‐methyl glycoside methyl ester. The stable structures of Neu5Acα are reasonable for the following sialooligosaccharide ligand studies with respect to the relationship between OH group orientations and intramolecular hydrogen bond formations. The barrier heights for isomerizations between the stable structures were computed to be 2.8 to 6.7 kcal/mol at the B3LYP/6‐31++G(d,p)//B3LYP/6‐31G(d,p) level, which are basic factors for the conformational behavior of Neu5Acα before its interactions with receptors. We also calculated Neu5Acα–4 or 5‐water complexes to take account of the solvent effect on the intramolecular hydrogen bonds in the stable structures. Consequently, the structures of Neu5Acα in the complexes are similar to each other, which is consistent with the known NMR data. Thus, the optimum Neu5Acα‐water complexes are some of the reasonable pseudohydrous Neu5Acα.
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