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Photo-promoted cascade 6-exo-trig spirocyclization of biaryl ynones with NH4SCN was developed for the preparation of various SCN-containing spiro[5,5]trienones.

The B cell receptor (BCR) complex plays a critical role in B cell development and immune responses. The assembly mechanisms underlying the BCR complex remain unknown. We determined the cryo–electron microscopy (cryo-EM) structures of human IgG-BCR and IgM-BCR, which consist of membrane-bound immunoglobulin molecules (mIg) and Igα/β subunits at a 1:1 stoichiometry. Assembly of both BCR complexes involves their extracellular domains, membrane-proximal connection peptides, and transmembrane (TM) helices. The TM helices of mIgG and mIgM share a conserved set of hydrophobic and polar interactions with Igα/β TM helices. By contrast, the IgG-Cγ3 and IgM-Cμ4 domains interact with extracellular Ig-like domains of Igα/β through head-to-tail and side-by-side modes, respectively. This work reveals the structural basis for BCR assembly and provides insights into BCR triggering.

Histamine receptors play important roles in various pathophysiological conditions and are effective targets for anti-allergy treatment, however the mechanism of receptor activation remain elusive. Here, we present the cryo-electron microscopy (cryo-EM) structure of the human H1R in complex with a Gq protein in an active conformation via a NanoBiT tethering strategy. The structure reveals that histamine activates receptor via interacting with the key residues of both transmembrane domain 3 (TM3) and TM6 to squash the binding pocket on the extracellular side and to open the cavity on the intracellular side for Gq engagement in a model of “squash to activate and expand to deactivate”. The structure also reveals features for Gq coupling, including the interaction between intracellular loop 2 (ICL2) and the αN-β junction of Gq/11 protein. The detailed analysis of our structure will provide a framework for understanding G-protein coupling selectivity and clues for designing novel antihistamines. Histamine receptors are effective targets for allergy treatments and antihistamines are the first choice of many allergic disorders, but the exact mechanism of agonist binding and receptor activation remain unknown. Here, the authors present the cryo-EM structure of histamine-bound H1R/Gq complex and propose a mechanism of ligand induced receptor activation.

Adhesion G-protein-coupled receptors (aGPCRs) play key roles in a diversity of physiologies. A hallmark of aGPCR activation is the removal of the inhibitory GAIN domain and the dipping of the cleaved stalk peptide into the ligand-binding pocket of receptors; however, the detailed mechanism remains obscure. Here, we present cryoelectron microscopy (cryo-EM) structures of ADGRL3 in complex with G

In the application of classical graph theory, there always are various indeterministic factors. This study studies the indeterministic factors in the connected graph by employing the uncertainty theory. First, this study puts forward two concepts: generalized uncertain graph and its connectivity index. Second, it presents a new algorithm to compute the connectivity index of an uncertain graph and generalized uncertain graph and verify this algorithm with typical examples. In addition, it proposes the definition and algorithm of α -connectivity index of generalized uncertain graph and verifies the stability and efficiency of this new algorithm by employing numerical experiments.

Cholesterol molecules specifically bind to the resting αβTCR to inhibit cytoplasmic CD3ζ ITAM phosphorylation through sequestering the TCR-CD3 complex in an inactive conformation. The mechanisms of cholesterol-mediated inhibition of TCR-CD3 and its activation remain unclear. Here, we present cryoelectron microscopy structures of cholesterol- and cholesterol sulfate (CS)-inhibited TCR-CD3 complexes and an auto-active TCR-CD3 variant. The structures reveal that cholesterol molecules act like a latch to lock CD3ζ into an inactive conformation in the membrane. Mutations impairing binding of cholesterol molecules to the tunnel result in the movement of the proximal C terminus of the CD3ζ transmembrane helix, thereby activating the TCR-CD3 complex in human cells. Together, our data reveal the structural basis of TCR inhibition by cholesterol, illustrate how the cholesterol-binding tunnel is allosterically coupled to TCR triggering, and lay a foundation for the development of immunotherapies through directly targeting the TCR-CD3 complex.

Sphingosine-1-phosphate receptor 1 (S1PR1) is a master regulator of lymphocyte egress from the lymph node and an established drug target for multiple sclerosis (MS). Mechanistically, therapeutic S1PR1 modulators activate the receptor yet induce sustained internalization through a potent association with β-arrestin. However, a structural basis of biased agonism remains elusive. Here, we report the cryo-electron microscopy (cryo-EM) structures of G

Histamine receptors play important roles in various pathophysiological conditions and are effective targets for anti-allergy treatment, however the mechanism of receptor activation remain elusive. Here, we present the cryo-electron microscopy (cryo-EM) structure of the human H1R in complex with a Gq protein in an active conformation via a NanoBiT tethering strategy. The structure reveals that histamine activates receptor via interacting with the key residues of both transmembrane domain 3 (TM3) and TM6 to squash the binding pocket on the extracellular side and to open the cavity on the intracellular side for Gq engagement in a model of “squash to activate and expand to deactivate”. The structure also reveals features for Gq coupling, including the interaction between intracellular loop 2 (ICL2) and the αN-β junction of Gq/11 protein. The detailed analysis of our structure will provide a framework for understanding G-protein coupling selectivity and clues for designing novel antihistamines., Histamine receptors are effective targets for allergy treatments and antihistamines are the first choice of many allergic disorders, but the exact mechanism of agonist binding and receptor activation remain unknown. Here, the authors present the cryo-EM structure of histamine-bound H1R/Gq complex and propose a mechanism of ligand induced receptor activation.

Uniform AgCl nanocubes with an average size of about 360 nm have been synthesized. Under UV illumination, a layer of silver nanoparticles with surface plasmon resonance was produced and covered the surface of AgCl particles in a short time, and the Ag/AgCl particles remained quite stable as shown in XRD patterns. The as-synthesized AgCl particles were tried for the first time as photoinitiator to polymerize N-isopropylacrylamide under UV-irradiation, and a high efficiency and conversion rate were realized. The structure of the polymers was studied by FTIR spectrophotometer. The results of turbidimetric method showed that the polymers were temperature sensitive and their lower critical solution temperature was about 33 °C. The effects of photoinitiators concentration, monomers concentration, and irradiation time on the polymer yield were investigated. The reaction mechanism was discussed by using salicylic acid as scavengers of hydroxyl radicals and conducting the reaction under oxygen atmosphere, respectively. The results proved that hydroxyl radicals were essential to chain initiation.

With the wide use of cloud computing services, users require higher and higher security. So the safety of cloud computing is the first consideration of users to choose. In the development of cloud computing, the application proportion of virtualization gradually increase, the scope and depth of the safety gradually expand. The related concepts of cloud computing and development situation are introduced in this paper. Not only the key technologies of cloud computing security are analyzed, but also a cloud security framework is put forward combined with the current security problems needed to resolve in cloud computing. We analyze and compare the present research results of security model and mechanism in the cloud. At last, we propose a security mechanism based on cloud computing.

This paper explores dissimilarity method for summarization. Understands the text based on significance of the sentences, and generates summarization based on extractive strategy. It computed the significance feature of the sentences, then computed the representative power of the sentences, and ordered them and selected the top sentences to generate the summary. The Chinese corpus and DUC corpus are used to experiment. Experimental result shows that the proposed summarization method can improve the performance of summarization.

通讯作者地址: Zheng, NF (通讯作者), Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Xiamen 361005, Peoples R China 2. Xiamen Univ, Dept Chem, Xiamen 361005, Peoples R China 3. Univ Calif Santa Barbara, Dept Chem & Biochem, Santa Barbara, CA 93106 USA 电子邮件地址: nfzheng@xmu.edu.cn, stucky@chem.ucsb.edu

A microstructural investigation of oxide scales was carried out by analytical electron microscope (AEM) after the as-cast Ti42Al48Cr8Ag2 alloy was exposed to air at 1,173 K for 5, 30 and 180 min, respectively. The results indicated that the formation of oxide scale experiences a transformation from ternary-layer system consisting of an outmost rutile (TiO2-rich) layer, mid amorphous alumina and inner nitrides to a double-layer of TiO2 and Al2O3-rich with increasing time from 5 to 30 min. In the subsurface zone, a change was also found a metastable Cr-rich new phase with bcc structure of a = 1.371 nm formed in addition to the oxidation for X-phase during 30 min. After 180 min, a continuous Laves-phase layer formed instead at the same position. In addition, the process revealed that amorphous alumina changed to a metastable structure before stable α-Al2O3 formed.

In the present work, microstructure of oxide scale of Ti–46.5Al–5Nb oxidized for 50 h at 900 °C in air was investigated in both plane-viewed and cross-sectional samples using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). In the TiO 2 and Al 2 O 3 mixture layer, orientation relationships (OR) between the Al 2 O 3 and TiO 2 phases were identified to be [ 1 1 ¯ 0 ] Al 2 O 3 / / [ 001 ] TiO 2 and ( 001 ) Al 2 O 3 / / ( 110 ) TiO 2 , however, some misorientation existed at their interface. Besides, Nb enrichment was detected in the TiO 2 phase in this layer but no Nb was found in the outer TiO 2 layer. Al 3 Nb phase was identified between the oxide scale and TiAl base. This phase would promote TiAl oxidation protection due to hinder ‘x’ phase continuous formation.

The oxidation of Ti-48Al-8Cr-2Ag (at.%) was studied for 50 h at 900 and 1000 degrees C. The microstructure of the oxide scales was characterized by means of scanning-electron microscopy (SEM) and high-resolution electron microscopy (HREM). The results showed that the mass gain of the alloy at 1000 degrees C was lower than that at 900 degrees C. At 1000 degrees C, a continuous and dense scale of quite pure Al2O3 formed, but at 900 degrees C, a complex scale with an outer layer of Al2O3 + TiO2 and an layer of inner Al2O3. A Laves phase and a Z-phase were found at the scale/substrate interface, which might be a factor beneficial to the formation of Al2O3.

Adaptive modulation is an effective means to make full use of wireless channel capacity and average spectral efficiency in multiple input multiple output systems. Based on the optimal bit allocation algorithm in MIMO systems, a new algorithm was proposed which calculate the total power constraint for each sub-channel to determine the modulation mode by rounding down means. Then according to the residual power, the modulation order was revised. The proposed scheme makes full use of the residual power and speeds the algorithm convergence. The program flow of the new algorithm not only adapts to adaptive modulation based on maximum average spectrum efficiency, but also suitable for minimum transmit power algorithm. Simulation results show that the proposed algorithm can greatly reduce the complexity of computing.

A novel fingerprint matching algorithm based on quadrangles has been developed. To begin with, we extracted ridge lines from fingerprints, and three phases were performed to match the ridge lines between two fingerprints. In the first phase, an inaccurate set of matched line pairs were built by matching the local quadrangle set (LQS). In the second phase, the fake pairs were removed from the set by evaluating the correlation among the pairs. A decision for the two fingerprints coming from the same finger or not could be made based on the shrunken set in case there were enough pairs in the set, otherwise the set was extended by adding the possible matched pairs that failed matching in the first phase so that a more reliable decision could be made. Experiments using the FVC2002 (Fingerprint verification competition 2000) databases show that the proposed algorithm is effective.

Efficiency simplified: A synthetic strategy has been developed to prepare single-crystalline hollow Pd/Pt nanocubes (right, see picture; left: nanocubes). Compared to the solid Pd/Pt nanocubes of similar sizes, the hollow Pd/Pt nanocubes increase accessible surface area and therefore improve electrocatalytic activity in formic acid oxidation.

Although solution-based synthesis is the most powerful and economic method to create nanostructured anatase TiO(2), under those synthesis conditions the {101} facets are the most thermodynamically stable, making it difficult to create anatase nanomaterials with a large percentage of high-energy {001} or {010} facets exposed. Here, we report a facile nonaqueous synthetic route to prepare anatase nanosheets with exposed {001} facets and high-quality rhombic-shaped anatase nanocrystals with a large percentage of exposed {010} facets. Including adscititious water in the nonaqueous synthesis and eliminating the use of carboxylic acid type capping agents are the two keys to integrating the structural diversity from aqueous systems into large-quantity synthesis in nonaqueous systems. The nanostructured TiO(2) that we prepared exhibits conspicuous activity in the photocatalytic degradation of organic contaminants.