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Search Results: 1 - 10 of 34399 matches for " Daguang Lu "
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Ultrastructural Characterization of Olfactory Sensilla and Immunolocalization of Odorant Binding and Chemosensory Proteins from an Ectoparasitoid Scleroderma guani (Hymenoptera: Bethylidae)
Xiangrui Li, Daguang Lu, Xiaoxia Liu, Qingwen Zhang, Xuguo Zhou
International Journal of Biological Sciences , 2011,
Abstract: The three-dimensional structures of two odorant binding proteins (OBPs) and one chemosensory protein (CSP) from a polyphagous ectoparasitoid Scleroderma guani (Hymenoptera: Bethylidae) were resolved bioinformatically. The results show that both SguaOBP1 and OBP2 are classic OBPs, whereas SguaCSP1 belongs to non-classic CSPs which are considered as the “Plus-C” CSP in this report. The structural differences between the two OBPs and between OBP and CSP are thoroughly described, and the structural and functional significance of the divergent C-terminal regions (e.g., the prolonged C-terminal region in SguaOBP2 and the additional pair of cysteines in SguaCSP1) are discussed. The immunoblot analyses with antisera raised against recombinant SguaOBP1, OBP2, and CSP1, respectively, indicate that two SguaOBPs are specific to antennae, whereas SguaCSP1, which are more abundant than OBPs and detected in both male and female wasps, expresses ubiquitously across different tissues. We also describe the ultrastructure of the antennal sensilla types in S. guani and compare them to 19 species of parasitic Hymenoptera. There are 11 types of sensilla in the flagellum and pedicel segments of antennae in both male and female wasps. Seven of them, including sensilla placodea (SP), long sensilla basiconica (LSB), sensilla coeloconica (SC), two types of double-walled wall pore sensilla (DWPS-I and DWPS-II), and two types of sensilla trichodea (ST-I and ST-II), are multiporous chemosensilla. The ultralsturctures of these sensilla are morphologically characterized. In comparison to monophagous specialists, the highly polyphagous generalist ectoparasitoids such as S. guani possess more diverse sensilla types which are likely related to their broad host ranges and complex life styles. Our immunocytochemistry study demonstrated that each of the seven sensilla immunoreacts with at least one antiserum against SguaOBP1, OBP2, and CSP1, respectively. Anti-OBP2 is specifically labeled in DWPS-II, whereas the anti-OBP1 shows a broad spectrum of immunoactivity toward four different sensilla (LSB, SP, ST-I and ST-II). On the other hand, anti-CSP1 is immunoactive toward SP, DWPS-I and SC. Interestingly, a cross co-localization pattern between SguaOBP1 and CSP1 is documented for the first time. Given that the numbers of OBPs and CSPs in many insect species greatly outnumber their antennal sensilla types, it is germane to suggest such phenomenon could be the rule rather than the exception.
Extrinsic eigenvalue estimates of the Dirac operator
Daguang Chen
Mathematics , 2007,
Abstract: For a compact spin manifold $M$ isometrically embedded into Euclidean space, we derive the extrinsic estimates from above and below for eigenvalues of the Dirac operators, which depend on the second fundamental form of the embedding. We also show the bounds of the ratio of the eigenvalues.
Eigenvalue estimates for Dirac operator with the generalized APS boundary condition
Daguang Chen
Mathematics , 2007, DOI: 10.1016/j.geomphys.2006.03.009
Abstract: Under two boundary conditions, the generalized Atiyah-Patodi-Singer boundary condition and the modified generalized -Atiyah-Patodi-Singer boundary condition, we get the lower bounds for the eigenvalues of the fundamental Dirac operator on compact spin manifolds with nonempty boundary.
Second Eigenvalue of Paneitz Operators and Mean Curvature
Daguang Chen,Haizhong Li
Mathematics , 2010, DOI: 10.1007/s00220-011-1281-2
Abstract: For $n\geq 7$, we give the optimal estimate for the second eigenvalue of Paneitz operators for compact $n$-dimensional submanifolds in an $(n+p)$-dimensional space form.
The sharp estimates for the first eigenvalue of Paneitz operator on 4-dimensional submanifolds
Daguang Chen,Haizhong Li
Mathematics , 2010,
Abstract: In this note, we obtain the sharp estimates for the first eigenvalue of Paneitz operator for $4$-dimensional compact submanifolds in Euclidean space. Since unit spheres and projective spaces can be canonically imbedded into Euclidean space, the corresponding estimates for the first eigenvalue are also obtained.
Inequalities for eigenvalues of the weighted Hodge Laplacian
Daguang Chen,Yingying Zhang
Mathematics , 2013,
Abstract: In this paper, we obtain "universal" inequalities for eigenvalues of the weighted Hodge Laplacian on a compact self-shrinker of Euclidean space. These inequalities generalize the Yang-type and Levitin-Parnovski inequalities for eigenvalues of the Laplacian and Laplacian. From the recursion formula of Cheng and Yang \cite{ChengYang07}, the Yang-type inequality for eigenvalues of the weighted Hodge Laplacian are optimal in the sense of the order of eigenvalues.
Experimental Observation of Early Stage Taylor Dispersion
初期Taylor弥散实验观察

Xi Daguang,
陈家骅

实验力学 , 1993,
Abstract: Taylor dispersion process of initial density distribution with stepped change was observed in short-duration steady flow field of a shock-tube.The substance measured was the component CO_2 in air.The measurement was carried out by means of infrared spectrums absorption method.The physical process observed in within a duration less than 0.07 dimensionless time.The comparison of measured data with theoretical results shows that turbulent Taylor dispersion is of symmetrical manner in its early stage.
Poly[[diaquabis{μ-4-[6-(4-carboxyphenyl)-4,4′-bipyridin-2-yl]benzoato-κ2O:N1′}copper(II)] dimethylformamide tetrasolvate]
Yabin Sun,E Song,Daguang Wang
Acta Crystallographica Section E , 2013, DOI: 10.1107/s1600536813006430
Abstract: In the title compound, {[Cu(C24H15N2O4)2(H2O)2]·4C3H7NO}n, the CuII ion, lying on an inversion center, is six-coordinated by two N atoms from two 4-[6-(4-carboxyphenyl)-4,4′-bipyridin-2-yl]benzoate (L) ligands, two deprotonated carboxylate O atoms from two other symmetry-related L ligands and two water molecules in a slightly distorted octahedral geometry. The CuII atoms are linked by the bridging ligands into a layer parallel to (101). The presence of intralayer O—H...O hydrogen bonds and π–π interactions between the pyridine and benzene rings [centroid–centroid distances = 3.808 (2) and 3.927 (2) ] stabilizes the layer. Further O—H...O hydrogen bonds link the layers and the dimethylformamide solvent molecules.
The sharp estimates of eigenvalues of Polyharmonic operator and higher order Stokes operator
Daguang Chen,He-Jun Sun
Mathematics , 2014,
Abstract: In this paper, we establish some lower bounds for the sums of eigenvalues of the polyharmonic operator and higher order Stokes operator, which are sharper than the recent results in \cite{CSWZ13, I13}. At the same time, we obtain some certain bounds for the sums of positive and negative powers of eigenvalues of the polyharmonic operator.
Estimates of the gaps between consecutive eigenvalues of Laplacian
Daguang Chen,Tao Zheng,Hongcang Yang
Mathematics , 2013,
Abstract: By the calculation of the gap of the consecutive eigenvalues of $\Bbb S^n$ with standard metric, using the Weyl's asymptotic formula, we know the order of the upper bound of this gap is $k^{\frac{1}{n}}.$ We conjecture that this order is also right for general Dirichlet problem of the Laplace operator, which is optimal if this conjecture holds, obviously. In this paper, using new method, we solve this conjecture in the Euclidean space case intrinsically. We think our method is valid for the case of general Riemannian manifolds and give some examples directly.
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