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    An ice making apparatus of a refrigerator comprises at least one ice cell (1) and a bracket (2). The ice cell (1) is mounted on the bracket (2). The bracket (2) is fixed on a door of the refrigerator. A rotating structure is disposed at the connection position of the ice cell (1) and the bracket (2). The ice making apparatus also comprises a pull rod (5) capable of moving perpendicularly to the door. The pull rod (5) is mounted on the bracket (2). The ice making apparatus also comprises a transmission structure (6) for driving the ice cell (1) to overturn. One end of the transmission structure (6) is connected to the ice cell (1), and the other end of the transmission structure (6) is connected to the pull rod (5), so that the movement of pulling the pull rod (5) can drive the movement of the transmission structure (6) connected to the pull rod (5), and the transmission structure (6) drives the ice cell (1) connected to the transmission structure (6) to overturn and distort towards the outer side of the door of the refrigerator so as to unload ice. The ice making apparatus is also provided with a reset structure (4) for resetting the ice cell (1). By means of the transmission structure (6), a user can unload ice in the ice cell (1) without applying excessive force, and the ice unloading process is simple and convenient.
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    A nitrogen preservation drawer is used in a freezer and comprises a drawer chamber (1), a drawer cover component (2), a gas inlet (3), a gas extraction opening (4) and a gas extraction device (5), the gas inlet (3) and the gas extraction opening (4) are formed in the drawer chamber (1), the gas extraction end of the gas extraction device (5) is connected to the gas extraction opening (4) through a pipeline, a gas separation device (6) is disposed on the drawer chamber (1), the gas discharge end of the gas separation device (6) is connected to the gas inlet (3) through a pipeline, the gas inlet end of the gas separation device (6) is connected to the gas outlet end of the gas extraction device (5) through a pipeline, a pressure relief component (7) is disposed on the drawer cover component (2), and a locking assembly (8) is disposed between the drawer chamber (1) and the drawer cover component (2). The drawer chamber (1) of the nitrogen preservation drawer can be independently disposed in the freezer, the inner structure of the original freezer is almost not influenced, the nitrogen separation mode, the pressure relief mode and the locking mode are simple and the nitrogen preservation drawer is convenient to use.
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  • Structural characterization of the HCoV-229E fusion core

    Zhang, Wei   Zheng, Qianqian   Yan, Mengrong   Chen, Xiaobo   Yang, Haitao   Zhou, Weihong   Rao, Zihe  

    HCoV-229E spike (S) protein mediates virion attachment to cells and subsequent fusion of the viral and cellular membranes. This protein is composed of an N-terminal receptor-binding domain (51) and a C-terminal trans-membrane fusion domain (52). S2 contains a highly conserved heptad repeat 1 and 2 (HR1 and HR2). In this study, the HRs sequences were designed and connected with a flexible linker. The recombinant fusion core protein was crystallized and its structure was solved at a resolution of 2.45 angstrom. Then we characterized the binding of HR1s and HR2s via both sequence alignment and structural analysis. The overall structures, especially the residues in some positions of HR2 are highly conserved. Fourteen hydrophobic and three polar residues from each HR1 peptide are packed in layers at the coiled-coil interface. These core amino acids can be grouped into seven heptad repeats. Analysis of hydrophobic and hydrophilic interactions between HR2 helix and HR1 helices, shows that the HR1 and HR2 poly peptides are highly complementary in both shape and chemical properties. Furthermore, the available knowledge concerning HCoV-229E fusion core may make it possible to design small molecule or poly peptide drugs targeting membrane fusion, a crucial step of HCoV-229E infection. (C) 2018 Elsevier Inc. All rights reserved.
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  • Crystal structure of a tankyrase 1-telomere repeat factor 1 complex

    Li, Bo   Qiao, Ruihong   Wang, Zhizhi   Zhou, Weihong   Li, Xin   Xu, Wenqing   Rao, Zihe  

    Telomere repeat factor 1 (TRF1) is a subunit of shelterin (also known as the telosome) and plays a critical role in inhibiting telomere elongation by telomerase. Tankyrase 1 (TNKS1) is a poly(ADP-ribose) polymerase that regulates the activity of TRF1 through poly(ADP-ribosyl) ation (PARylation). PARylation of TRF1 by TNKS1 leads to the release of TRF1 from telomeres and allows telomerase to access telomeres. The interaction between TRF1 and TNKS1 is thus important for telomere stability and the mitotic cell cycle. Here, the crystal structure of a complex between the N-terminal acidic domain of TRF1 (residues 1-55) and a fragment of TNKS1 covering the second and third ankyrin-repeat clusters (ARC2-3) is presented at 2.2 angstrom resolution. The TNKS1-TRF1 complex crystals were optimized using an 'oriented rescreening' strategy, in which the initial crystallization condition was used as a guide for a second round of large-scale sparse-matrix screening. This crystallographic and biochemical analysis provides a better understanding of the TRF1-TNKS1 interaction and the three-dimensional structure of the ankyrin-repeat domain of TNKS.
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  • Ultrastructural Analysis of Human Gallstones using Synchrotron Radiation mu CT

    Chen, Weixin   Liu, Riming   Tao, Suo   Shen, Weixing   Zhou, Weihong   Song, Chao   Lu, Huanhua   Xing, Chungen  

    Objective: Gallstone formation is a pathological process of mineralization in the human body. Determination of the morphology and ultrastructure of gallstones holds the key to understanding the pathophysiology of gallbladder disease. Synchrotron radiation phase-contrast Xray microtomography is a novel technology, which is designed for comprehensive analysis of gallstone ultrastructure. Materials and Methods: Nine human gallstones were obtained from the Department of Pathology, Qingpu branch of Zhongshan Hospital Affiliated to Fudan University (China), and scanned by synchrotron radiation mu CT (SR mu CT). The imaging data generated by SR mu CT scan were analyzed. Results: The three-dimensional ultrastructure of human gallstones corresponding to their cholesterol and bile pigment composition was determined. Conclusions: The ultrastructure of gallstones exhibits considerable diversity and complexity. The synchrotron radiation phase-contrast X-ray microtomography is a valuable tool for in-depth study of human gallstones.
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  • Catalytic Pyrolysis of Herb Residues for the Preparation of Hydrogen-Rich Gas

    Zhao, Baofeng   Song, Ge   Zhou, Weihong   Chen, Lei   Sun, Laizhi   Yang, Shuangxia   Guan, Haibin   Zhu, Di   Chen, Guanyi   Ding, Weijing   Wang, Jingwei   Yang, Huajian  

    Thermochemical conversion technology for the resource utilization of biomass can not only treat wastes polluting the environment but also efficiently generate hydrogen-rich gas for industrial applications. In this paper, the simulation calculation and experimental studies were employed to investigate the catalytic pyrolysis of herb residues for the preparation of hydrogen-rich gas. The results of thermogravimetry-Fourier transform infrared, kinetic, and thermodynamic studies showed that the catalytic pyrolysis of herb residues by 10 wt % Ni/CaO catalyst exhibited the lowest apparent activation energy compared to pyrolysis catalyzed with CaO or no catalyst. Under the catalysis of 10 wt % Ni/CaO and the temperature range of 500-700 degrees C, the content of H-2 in the catalytic pyrolysis gas products of herb residues was higher, while the content of CO2 was lower. Furthermore, in the presence of 10 wt % Ni/CaO catalyst, the catalytic pyrolysis experiment of herb residues in a moving bed reactor was carried out at 500-700 degrees C. The results showed that the distribution of hydrogen-rich gas composition with an increasing temperature was consistent with the thermodynamic simulation results. Specifically, with a rising pyrolysis temperature, the H-2 content increased initially and then decreased, which reached the highest ratio at 650 degrees C with an experimental value of 67.31 vol %.
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  • Structural analysis of molybdopterin synthases from two mycobacterial pathogens

    Wang, Huiying   Chen, Xiaobo   Zhang, Wei   Zhou, Weihong   Liu, Xiang   Rao, Zihe  

    The molybdenum cofactor, composed of molybdopterin and molybdenum, is a necessary compound for the catalytic activity of molybdenum enzymes. Molybdenum cofactor biosynthesis is a conserved multistep process involving several enzymes. Molybdopterin synthase, a hetero-tetrameric enzyme composed of a pair of MoaE-MoaD subunits, catalyzes the generation of the cis-dithiolene group of molybdopterin in the second step of the process. The cis-dithiolene group can covalently bind molybdenum. Most mycobacterial species possess several genes encoding the full pathway of molybdenum cofactor biosynthesis. In M. smegmatis, the moaD2 and moaE2 genes encode the functional molybdopterin synthase. However, M. tuberculosis has genes encoding several molybdopterin synthase subunit homologs, including moaD1, moaD2, moaE1, moaE2, and moaX, which encodes a MoaD-MoaE fusion protein. Previous studies have shown that moaD2 and moaE2 encode functional molybdopterin synthase. Here, we report the crystal structures of two substrate-free molybdopterin synthases from two different mycobacterial pathogens, M. tuberculosis and M. smegmatis, at 2.1 angstrom and 2.6 angstrom resolutions, respectively. The overall structure of both molybdopterin synthases was hetero-tetrameric, consisting of a MoaE2 dimer flanked on either side by single MoaD2 subunits. The carboxyl-terminal domain of MoaD2 inserted into MoaE2, forming the active pocket. A comparison with previously reported molybdopterin synthase structures showed that substrate-binding and catalytic residues were conserved, despite low sequence similarity among these enzymes. The low sequence identity at the MoaE-MoaD heterodimer interface may provide the structural basis to explore mycobacterial inhibitors. (C) 2019 Elsevier Inc. All rights reserved.
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    A drinking device and a refrigerator provided with same. The drinking device comprises a water storage box (2), wherein the water storage box (2) comprises a water storage box cover (21), a deflecting tray (22) and a water storage box main body (23) which are detachably assembled together; a filter element is arranged in the deflecting tray (22); the deflecting tray (22) is positioned in the water storage box main body (23) and is provided with a deflection port (221) for allowing water to flow into the water storage box main body (23) from the deflecting tray (22); and a sealing water outlet part through which the water flows out is arranged at the bottom of the water storage box main body (23). The drinking device is assembled on an inner container of a refrigerator door body (1); and a receiving port for accommodating the water flowing out of the drinking device is formed outside the refrigerator door body (1). The drinking device provided by the invention has the advantages of filtering function, water leakage resistance, high water outlet speed, simple structure, easiness in cleaning and low cost; and in addition, the drinking device is detachably and movably connected with the refrigerator, and thus the utilization rate of the volume of the refrigerator is improved.
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  • Gastrointestinal pathology in juvenile and adult CFTR-knockout ferrets.

    Sun, Xingshen   Olivier, Alicia K   Yi, Yaling   Pope, Christopher E   Hayden, Hillary S   Liang, Bo   Sui, Hongshu   Zhou, Weihong   Hager, Kyle R   Zhang, Yulong   Liu, Xiaoming   Yan, Ziying   Fisher, John T   Keiser, Nicholas W   Song, Yi   Tyler, Scott R   Goeken, J Adam   Kinyon, Joann M   Radey, Matthew C   Fligg, Danielle   Wang, Xiaoyan   Xie, Weiliang   Lynch, Thomas J   Kaminsky, Paul M   Brittnacher, Mitchell J   Miller, Samuel I   Parekh, Kalpaj   Meyerholz, David K   Hoffman, Lucas R   Frana, Timothy   Stewart, Zoe A   Engelhardt, John F  

    Cystic fibrosis (CF) is a multiorgan disease caused by loss of a functional cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel in many epithelia of the body. Here we report the pathology observed in the gastrointestinal organs of juvenile to adult CFTR-knockout ferrets. CF gastrointestinal manifestations included gastric ulceration, intestinal bacterial overgrowth with villous atrophy, and rectal prolapse. Metagenomic phylogenetic analysis of fecal microbiota by deep sequencing revealed considerable genotype-independent microbial diversity between animals, with the majority of taxa overlapping between CF and non-CF pairs. CF hepatic manifestations were variable, but included steatosis, necrosis, biliary hyperplasia, and biliary fibrosis. Gallbladder cystic mucosal hyperplasia was commonly found in 67% of CF animals. The majority of CF animals (85%) had pancreatic abnormalities, including extensive fibrosis, loss of exocrine pancreas, and islet disorganization. Interestingly, 2 of 13 CF animals retained predominantly normal pancreatic histology (84% to 94%) at time of death. Fecal elastase-1 levels from these CF animals were similar to non-CF controls, whereas all other CF animals evaluated were pancreatic insufficient (<2 mug elastase-1 per gram of feces). These findings suggest that genetic factors likely influence the extent of exocrine pancreas disease in CF ferrets and have implications for the etiology of pancreatic sufficiency in CF patients. In summary, these studies demonstrate that the CF ferret model develops gastrointestinal pathology similar to CF patients. Copyright =C2=A9 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
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  • Openclosed motion of Mint2 regulates APP metabolism

    Xie, Xingqiao   Yan, Xiaojie   Wang, Zheng   Zhou, Hao   Diao, Wentao   Zhou, Weihong   Long, Jiafu   Shen, Yuequan  

    The amyloid- protein precursor (APP) plays a crucial role in the pathogenesis of Alzheimers disease (AD). Knock-out and transgenic mouse studies of the adaptor protein Mint2 have revealed that it is a major player in regulating APP metabolism physiologically through the binding of its phosphotyrosine-binding (PTB) domain to the intracellular domain of APP. However, the molecular mechanism of APP dynamically binding to Mint2 remains elusive. Here, we report the structures of APP peptide-free and APP peptide-bound C-terminal Mint2 mutants at resolutions of 2.7 and 3.3 , respectively. Our structures reveal that APP peptide-free Mint2 exists in a closed state in which the ARM domain blocks the peptide-binding groove of the PTB domain. In sharp contrast, APP peptide-bound Mint2 exists in an open state in which the ARM domain drastically swings away from the bound peptide. Mutants that control the openclosed motion of Mint2 dynamically regulated APP metabolism both in vitro and in vivo. Our results uncover a novel openclosed mechanism of the PTB domain dynamically binding to its peptide substrate. Moreover, such a conformational switch may represent a general regulation mode of APP family members by Mint proteins, providing useful information for the treatment of AD.
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  • Diaryl Hydrazones as Multifunctional Inhibitors of Amyloid Self-Assembly

    Toeroek, Bela   Sood, Abha   Bag, Seema   Tulsan, Relcha   Ghosh, Sanjukta   Borkin, Dmitry   Kennedy, Arleen R.   Melanson, Michelle   Madden, Richard   Zhou, Weihong   LeVine, Harry, III   Toeroek, Marianna  

    The design and application of an effective, new class of multifunctional small molecule inhibitors of amyloid self-assembly are described. Several compounds based on the diaryl hydrazone scaffold were designed. Forty-four substituted derivatives of this core structure were synthesized using a variety of benzaldehydes and phenylhydrazines and characterized. The inhibitor candidates were evaluated in multiple assays, including the inhibition of amyloid beta (A beta) fibrillogenesis and oligomer formation and the reverse processes, the disassembly of preformed fibrils and oligomers. Because the structure of the hydrazone-based inhibitors mimics the redox features of the antioxidant resveratrol, the radical scavenging effect of the compounds was evaluated by colorimetric assays against 2,2-diphenyl-1-picrylhydrazyl and superoxide radicals. The hydrazone scaffold was active in all of the different assays. The structure-activity relationship revealed that the substituents on the aromatic rings had a considerable effect on the overall activity of the compounds. The inhibitors showed strong activity in fibrillogenesis inhibition and disassembly, and even greater potency in the inhibition of oligomer formation and oligomer disassembly. Supporting the quantitative fluorometric and colorimetric assays, size exclusion chromatographic studies indicated that the best compounds practically eliminated or substantially inhibited the formation of soluble, aggregated A beta species, as well. Atomic force microscopy was also applied to monitor the morphology of A beta deposits. The compounds also possessed the predicted antioxidant properties; approximately 30% of the synthesized compounds showed a radical scavenging effect equal to or better than that of resveratrol or ascorbic acid.
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  • Structural insight into the central element assembly of the synaptonemal complex.

    Lu, Jing   Gu, Yanling   Feng, Jianrong   Zhou, Weihong   Yang, Xue   Shen, Yuequan  

    The key step in meiosis is synaptonemal complex formation, which mediates homologous chromosome alignment and synapsis. False pairing between homologous chromosomes produces infertility. Here, we present a crystal structure of the mouse meiosis-specific protein SYCE3, which is a component of the synaptonemal complex central element. Our studies show that functional SYCE3 most likely forms a dimer or higher order oligomer in cells. Furthermore, we demonstrate that the SYCE3 N-helix interacts with the SYCE1 C-helix, which is another central element component. Our results suggest that helical packing may mediate intra- or inter-association of each central element protein component, thereby playing an essential role in forming the synaptonemal complex central elements. =20
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  • A multi-dataset data-collection strategy produces better diffraction data

    Liu, Zhi-Jie   Chen, Lirong   Wu, Dong   Ding, Wei   Zhang, Hua   Zhou, Weihong   Fu, Zheng-Qing   Wang, Bi-Cheng  

    A multi-dataset (MDS) data-collection strategy is proposed and analyzed for macromolecular crystal diffraction data acquisition. The theoretical analysis indicated that the MDS strategy can reduce the standard deviation (background noise) of diffraction data compared with the commonly used single-dataset strategy for a fixed X-ray dose. In order to validate the hypothesis experimentally, a data-quality evaluation process, termed a readiness test of the X-ray data-collection system, was developed. The anomalous signals of sulfur atoms in zinc-free insulin crystals were used as the probe to differentiate the quality of data collected using different data-collection strategies. The data-collection results using home-laboratory-based rotating-anode X-ray and synchrotron X-ray systems indicate that the diffraction data collected with the MDS strategy contain more accurate anomalous signals from sulfur atoms than the data collected with a regular data-collection strategy. In addition, the MDS strategy offered more advantages with respect to radiation-damage-sensitive crystals and better usage of rotating-anode as well as synchrotron X-rays.
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  • Structural genomics reveals EVE as a new ASCH/PUA-related domain

    Bertonati, Claudia   Punta, Marco   Fischer, Markus   Yachdav, Guy   Forouhar, Farhad   Zhou, Weihong   Kuzin, Alexander P.   Seetharaman, Jayaraman   Abashidze, Mariam   Ramelot, Theresa A.   Kennedy, Michael A.   Cort, John R.   Belachew, Adam   Hunt, John F.   Tong, Liang   Montelione, Gaetano T.   Rost, Burkhard  

    We report on several proteins recently solved by structural genomics consortia, in particular by the Northeast Structural Genomics consortium (NESG). The proteins considered in this study differ substantially in their sequences but they share a similar structural core, characterized by a pseudobarrel five-stranded beta sheet. This core corresponds to the PUA domain-like architecture in the SCOP database. By connecting sequence information with structural knowledge, we characterize a new subgroup of these proteins that we propose to be distinctly different from previously described PUA domain-like domains such as PUA proper or ASCH. We refer to these newly defined domains as EVE. Although EVE may have retained the ability of PUA domains to bind RNA, the available experimental and computational data suggests that both the details of its molecular function and its cellular function differ from those of other PUA domain-like domains. This study of EVE and its relatives illustrates how the combination of structure and genomics creates new insights by connecting a cornucopia of structures that map to the same evolutionary potential. Primary sequence information alone would have not been sufficient to reveal these evolutionary links.
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  • Purification of S-PG05 using Simulated Moving Bed Chromatography

    Zhou, Weihong   Lan, Shaopeng   Wang, Jida   Lin, Bingchang  

    S-PG05 ((15S)-15-methyl-prostaglandin F(2)alpha methyl ester) was separated from the epimer R-PG05 and other impurities using SMB, combined with batch chromatography. Based on this technical procedure, 94% pure S-PG05 was obtained. Different column configurations and separation conditions of SMB have been selected. A non-synchronous shift with a "partial extract withdrawal'' strategy has been employed, resulting in the saving of desorbent and the increase of the purity of S-PG05.
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  • Crystal structure of the apurinic/apyrimidinic endonuclease IV from Mycobacterium tuberculosis

    Zhang, Wei   Xu, Yueyang   Yan, Mengrong   Li, Shanshan   Wang, Huiying   Yang, Haitao   Zhou, Weihong   Rao, Zihe  

    Endonuclease IV is a typical endonuclease of the apurinic-apyrimidinic (AP) or abasic endonuclease superfamily. It repairs damaged DNA through base excision repair by cleaving the DNA backbone immediately 5' of an AP site. In Mycobacterium tuberculosis, endonuclease IV is the major AP endonuclease. This enzyme is absent from mammalian cells, making it an attractive target for anti-tuberculosis drug development. In this study, the structure of the recombinant endonuclease IV from M. tuberculosis (MtbEndo IV) was determined at a high resolution of 1.18 angstrom. MtbEndo IV was found to have a classical alpha 8 beta 8-fold TIM barrel with loops on its surface connecting the alpha-helices and beta-strands that constitute a groove for DNA binding. Three zinc ions were identified at the active site. A comparison between the structures of MtbEndo IV and Escherichia coli End IV suggested that Gln32 of MtbEndo IV may plays a role in regulating substrate binding. (C) 2018 Published by Elsevier Inc.
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