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27 results on '"Yang, Yihu"'

3. Examples of manifolds of positive Ricci curvature with quadratically nonnegatively curved infinity and infinite topological type

Author

Jiang, Huihong and Yang, Yihu

Subjects
Mathematics - Differential Geometry
Abstract

In this paper, we construct a complete n-dim Riemannian manifold with positive Ricci curvature, quadratically nonnegatively curved infinity and infinite topological type. This gives a negative answer to a conjecture by Jiping Sha and Zhongmin Shen in the case of n greater than or equal to 6.

Published
2017

5. Heat flow for horizontal harmonic maps into a class of Carnot-Caratheodory spaces

Author

Jost, Juergen and Yang, Yihu

Subjects
Mathematics - Differential Geometry, Mathematics - Complex Variables, 58E20
Abstract

We deform a map into a Riemannian manifold that is horizontal with respect to a submersion onto a non-positively curved manifold and satisfies a Chow condition into a harmonic one through a horizontal homotopy.

Published
2003

6. The cohomology of a variation of polarized Hodge structures over a quasi-compact K\'ahler manifold

Author

Jost, Juergen, Yang, Yihu, and Zuo, Kang

Subjects
Mathematics - Algebraic Geometry, Mathematics - Algebraic Topology, Mathematics - Differential Geometry, 14F99
Abstract

A systematic study of the contributions at infinity for the cohomology of variations of polarized Hodge structures over quasicompact K\"ahler manifolds. Several isomorphisms between different cohomologies given.

Published
2003

7. K\'ahler manifolds and fundamental groups of negatively $\delta$-pinched manifolds

Author

Jost, Juergen and Yang, Yihu

Subjects
Mathematics - Differential Geometry, Mathematics - Algebraic Geometry, 14E20, 58E20
Abstract

The fundamental group of a Riemannian manifold with $\delta$-pinched negative curvature, $\delta >1/4$, cannot be the fundamental group of a quasicompact K\"ahler manifold. The proof also implies that a non-uniform lattice in $F_{4(-20)}$ cannot be the fundamental group of a quasicompact K\"ahler manifold. We also construct examples in the spirit of Gromov-Thurston to show that our result is a non-trivial extension of the previously known result that a non-uniform lattice in real hyperbolic space in dimension at least 3 cannot be the fundamental group of a quasicompact K\"ahler manifold., Comment: Version with additional supplementary material to appear in Intern.J.Math

Published
2003

12. Graphene-Reinforced Biodegradable Resin Composites for Stereolithographic 3D Printing of Bone Structure Scaffolds

Author

Danna Tang, Zuying Feng, Tang Tian, Liang Hao, Yang Yihu, Wei Xiong, and Yan Li

Subjects
Materials science, Nanocomposite, Article Subject, business.industry, 3D printing, Casting, law.invention, chemistry.chemical_compound, Flexural strength, chemistry, law, lcsh:Technology (General), Ultimate tensile strength, lcsh:T1-995, General Materials Science, Composite material, business, Photoinitiator, Stereolithography, Polyurethane
Abstract

A biodegradable UV-cured resin has been fabricated via stereolithography apparatus (SLA). The formulation consists of a commercial polyurethane resin as an oligomer, trimethylolpropane trimethacrylate (TEGDMA) as a reactive diluent and phenylbis (2, 4, 6-trimethylbenzoyl)-phosphine oxide (Irgacure 819) as a photoinitiator. The tensile strength of the three-dimensional (3D) printed specimens is 68 MPa, 62% higher than that of the reference specimens (produced by direct casting). The flexural strength and modulus can reach 115 MPa and 5.8 GPa, respectively. A solvent-free method is applied to fabricate graphene-reinforced nanocomposite. Porous bone structures (a jawbone with a square architecture and a sternum with a round architecture) and gyroid scaffold of graphene-reinforced nanocomposite for bone tissue engineering have been 3D printed via SLA. The UV-crosslinkable graphene-reinforced biodegradable nanocomposite using SLA 3D printing technology can potentially remove important cost barriers for personalized biological tissue engineering as compared to the traditional mould-based multistep methods.

Published
2019

19. Tmem178 negatively regulates store-operated calcium entry in myeloid cells via association with STIM1

Author

Yang, Zhengfeng, primary, Yan, Hui, additional, Dai, Wentao, additional, Jing, Ji, additional, Yang, Yihu, additional, Mahajan, Sahil, additional, Zhou, Yubin, additional, Li, Weikai, additional, Macaubas, Claudia, additional, Mellins, Elizabeth D., additional, Shih, Chien-Cheng, additional, Fitzpatrick, James A.J., additional, and Faccio, Roberta, additional

Published
2019
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24. Membrane Protein Structure in Live Cells: Methodology for Studying Drug Interaction by Mass Spectrometry-Based Footprinting

Author

Shen, Guomin, Li, Shuang, Cui, Weidong, Liu, Shixuan, Yang, Yihu, Gross, Michael, and Li, Weikai

Abstract

Mass spectrometry-based footprinting is an emerging approach for studying protein structure. Because integral membrane proteins are difficult targets for conventional structural biology, we recently developed a mass spectrometry (MS) footprinting method to probe membrane protein–drug interactions in live cells. This method can detect structural differences between apo and drug-bound states of membrane proteins, with the changes inferred from MS quantification of the cysteine modification pattern, generated by residue-specific chemical labeling. Here, we describe the experimental design, interpretation, advantages, and limitations of using cysteine footprinting by taking as an example the interaction of warfarin with vitamin K epoxide reductase, a human membrane protein. Compared with other structural methods, footprinting of proteins in live cells produces structural information for the near native state. Knowledge of cellular conformational states is a necessary complement to the high-resolution structures obtained from purified proteins in vitro. Thus, the MS footprinting method is broadly applicable in membrane protein biology. Future directions include probing flexible motions of membrane proteins and their interaction interface in live cells, which are often beyond the reach of conventional structural methods.

Published
2018
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25. Warfarin traps human vitamin K epoxide reductase in an intermediate state during electron transfer

Author

Shen, Guomin, Cui, Weidong, Zhang, Hao, Zhou, Fengbo, Huang, Wei, Liu, Qian, Yang, Yihu, Li, Shuang, Bowman, Gregory R, Sadler, J Evan, Gross, Michael L, and Li, Weikai

Abstract

Although warfarin is the most widely used anticoagulant worldwide, the mechanism by which warfarin inhibits its target, human vitamin K epoxide reductase (hVKOR), remains unclear. Here we show that warfarin blocks a dynamic electron-transfer process in hVKOR. A major fraction of cellular hVKOR is in an intermediate redox state containing a Cys51-Cys132 disulfide, a characteristic accommodated by a four-transmembrane-helix structure of hVKOR. Warfarin selectively inhibits this major cellular form of hVKOR, whereas disruption of the Cys51-Cys132 disulfide impairs warfarin binding and causes warfarin resistance. Relying on binding interactions identified by cysteine alkylation footprinting and mass spectrometry coupled with mutagenesis analysis, we conducted structure simulations, which revealed a closed warfarin-binding pocket stabilized by the Cys51-Cys132 linkage. Understanding the selective warfarin inhibition of a specific redox state of hVKOR should enable the rational design of drugs that exploit the redox chemistry and associated conformational changes in hVKOR.

Published
2017
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27. [Synthesis and characterization of polylactide-based thermosetting polyurethanes with shape memory properties].

Author

Shi S, Gu L, Yang Y, Yu H, Chen R, Xiao X, and Qiu J

Subjects
Materials Testing, Polymers, Spectroscopy, Fourier Transform Infrared, Temperature, Biocompatible Materials chemistry, Polyesters chemistry, Polyurethanes chemistry
Abstract

A series of bio-based thermosetting polyurethanes (Bio-PUs) were synthesized by the crosslinking reaction of polylactide and its copolymers diols with hexamethylene diisocyanate (HDI) trimer. The obtained Bio-PUs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), universal tensile testing machine and cytotoxicity test. Results indicate that the PLA copolymer (P(LA-co-CL)) diols reduced the glass transition temperature (Tg) of Bio-PUs and improved their thermal stability, compared with PLA diols. The Bio-PUs synthesized from P (LA-co-CL) diols exhibit better mechanical performance and shape memory properties. Especially, Young modulus and elongation at break of the obtained Bio-PUs were 277.7 MPa and 230% respectively; the shape recovery time of the obtained Bio-PUs at body temperature was only 93 s. Furthermore, alamar blue assay results showed that the obtained Bio-PUs had no cell toxicity.

Published
2016
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