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Desulfurization is a versatile synthetic tool in organic synthesis, particularly in peptide chemistry, where it offers an effective conversion strategy for compounds that contain mercaptan groups.

A sulfonium ylide participated alkylation and arylation under transition-metal free conditions is described. The disparate reaction pattern allowed the separate activation of non-ylidic S-alkyl and S-aryl bond. Under acidic conditions, sulfonium ylides serve as alkyl cation precursors which facilitate the alkylations. While under alkaline conditions, cleavage of non-ylidic S-aryl bond produces O-arylated compounds efficiently. The robustness of the protocols were established by the excellent compatibility of wide variety of substrates including carbohydrates.

Fungal chitin, as a typical microorganism-associated molecular pattern (PAMP), was recognized by plant LysM-containing protein to induce immunity called pattern-triggered immunity (PTI). To successfully infect host plant, fungal pathogens secreted LysM-containing effectors to inhibit chitin-induced plant immunity. Filamentous fungus Colletotrichum gloeosporioides caused rubber tree anthracnose which resulted in serious loss of natural rubber production worldwide. However, little is known about the pathogenesis mediated by LysM effector of C. gloeosporioide. In this study, we identified a two LysM-containing effector in C. gloeosporioide and named as Cg2LysM. Cg2LysM was involved not only in conidiation, appressorium formation, invasion growth and the virulence to rubber tree, but also in melanin synthesis of C. gloeosporioides. Moreover, Cg2LysM showed chitin-binding activity and suppression of chitin-triggered immunity of rubber tree such as ROS production and the expression of defense relative genes HbPR1, HbPR5, HbNPR1 and HbPAD4. This work suggested that Cg2LysM effector facilitate infection of C. gloeosporioides to rubber tree through affecting invasive structure and inhibiting chitin-triggered plant immunity.

In an enterprise video conferencing system, the enterprise network can be shared by hundreds of video conferences. On the other hand, participants may not arrive at the same time and stay until the end of the conference. The abilities to reserve resources in advance, as well as effective dynamic multicast when participants can join and leave the conference at any time, are essential in the distributed multi-party video conferencing systems. However, the effective advance reservation strategies of the dynamic multicast requests for a heavy traffic case still remains open. In this paper, we investigate the problem of Maximizing the number of admitted Dynamic Multicast requests in the Advance Reservation environment (MDMAR) for the enterprise video conferencing system. We take two path schemes of a fixed path and variable paths, as well as a heterogeneous bandwidth reservation model into account. Firstly, we prove that the MDMAR problem is NP-complete and formulate it mathematically as an integer linear program (ILP) for small networks. Then, we develop greedy algorithms and simulated annealing (SA) algorithms for enterprise networks. Comparative simulations are performed to evaluate the heuristic algorithms for both small networks and enterprise networks. We find that the SA algorithms can provide within 6% lower optimal solutions than the ILP algorithms for our small network, and up to 10% improvement over the greedy algorithms for the large campus or enterprise network.

In an enterprise network, it is common to have hundreds of video conferences held simultaneously such that a large number of video streams need to be transmitted between participants in different geographical locations. For such a large transmission demand, an advance reservation (AR) system deployed for the video conferencing system can provide quality-of-service (QoS) guarantees to users and improve the resource utilization of the network. However, the effective resource reservation strategies for a heavy traffic case still remains open. In this paper, we propose an algorithm called the elastic timeslot-based advance reservation algorithm (ETARA), which aims at improving the resource utilization and reducing the computational complexity. A new time processing method, elastic timeslot, is proposed for the time domain management. Moreover, ETARA takes not only the processing time but also the resource usage into account. Comparative simulations with the existing two popular approaches, the dynamic timeslot-based approach and timeslot-based flexible approach, have been performed in terms of the acceptance ratio and runtime. The results show that with the same acceptance ratio, the runtime of ETARA can be up to 57 times lower than that of the flexible timeslot-based approach. Though ETARA has a slightly longer runtime than the dynamic approach, the acceptance ratio of ETARA can be twice as high as that of the dynamic timeslot-based approach.

When an emergency occurs on the train line, resulting in the loss of the carrying capacity of the railroad section, the subsequent train will be seriously affected, so the operation of the subsequent train must be adjusted. At present, most researchers’ train adjustment models aim at the minimum total train delay time, but do not consider the parking capacity of stations or even ignore the overtaking between trains, which are not applicable. The objective function of the train operation adjustment model proposed in this paper is to minimize the impact of emergencies on passengers. The constraints of parking capacity of each station and the overtaking between the express and the normal trains are considered comprehensively. The experiment results show that the model can describe the overtaking relationship between express and normal train. The model effectively obtains the train operation adjustment scheme and provides guidance for the railway operator to make the train operation adjustment decision when the emergency occurs.

In our recently developed interrupted Pummerer reaction mediated (IPRm) glycosylation with S-2-[(propan-2-yl)sulfinyl] benzyl (SPSB) glycosides as glycosyl donors, the anomeric leaving groups were ...

Attachment of various 3-aminodeoxy sugars to natural products or drugs is a prominent method for new drug development. However, access to structurally diversified 3-aminodeoxy sugars and glycosylation with aglycons are challenging. We synthesized a variety of unnatural 3-aminodeoxy sugars via diversified functionalization of a common glycal intermediate bearing a cyclic sulfamidate ketimine moiety. Based on these results, the α-selective glycosylation reactions of these 3-aminodeoxy sugars and the structural modification of diosgenin were further investigated.

The safety of urban rail vehicles is a crucial part in the operation of urban rail transit. Combining the concept of flexible management and the characteristics of urban rail vehicle operation and maintenance, this paper proposed the definition and process model of flexible operation and maintenance management of urban rail vehicles. Taking the vehicle door as a case, the activity-based classification is used to classify the vehicle equipment, and the decision tree method is used to determine the maintenance mode. The research work of this paper has theoretical significance and practical value for reducing the operation and maintenance cost of urban rail vehicles, improving the efficiency of maintenance and ensuring the safety of urban rail system.

A diversified synthesis of 3-aminosugar analogues of digitoxin and digoxin with potent anticancer activities was explored. The synthesis was based on a highly efficient gold-catalyzed glycosylation reaction with alkynylbenzoate 3-aminoglycosides as glycosyl donors. According to this strategy, a small library containing digitoxin and digoxin analogues with various 3-aminosugar scaffolds was successfully constructed.

Potassium (K) fixation and release in soil are important factors affecting K availability to plants and the utilization efficiency of K fertilizer. Three typical soils (red soil, yellow cinnamon soil, and alluvial soil) were collected from the middle and lower reaches of Yangtse River, China, to study the K-fixation and K-release characteristics of the normal and K-exhausted soil. Results showed that K fixation of added K in K-exhausted soils were significantly (P yellow cinnamon soil > alluvial soil, but the cumulative amount of K released from the three soils during successive extractions with 1.0 mol L−1 nitric acid (HNO3) was in the opposite order. The cumulative amounts of K released with 1.0 mol L−1 ammonium acetate (NH4OAc) and 1...

The ion channel formed by the homologous proteins MEC-4 and MEC-10 forms the core of a sensory mechanotransduction channel in Caenorhabditis elegans. Although the products of other mec genes are key players in the biophysics of transduction, the mechanism by which they contribute to the properties of the channel is unknown. Here, we investigate the role of two auxiliary channel subunits, MEC-2 (stomatin-like) and MEC-6 (paraoxonase-like), by coexpressing them with constitutively active MEC-4/MEC-10 heteromeric channels in Xenopus oocytes. This work extends prior work demonstrating that MEC-2 and MEC-6 synergistically increase macroscopic current. We use single-channel recordings and biochemistry to show that these auxiliary subunits alter function by increasing the number of channels in an active state rather than by dramatically affecting either single-channel properties or surface expression. We also use two-electrode voltage clamp and outside-out macropatch recording to examine the effects of divalent cations and proteases, known regulators of channel family members. Finally, we examine the role of cholesterol binding in the mechanism of MEC-2 action by measuring whole-cell and single-channel currents in MEC-2 mutants deficient in cholesterol binding. We suggest that MEC-2 and MEC-6 play essential roles in modulating both the local membrane environment of MEC-4/MEC-10 channels and the availability of such channels to be gated by force in vivo.

MEC-4 and MEC-10 are the pore-forming subunits of the sensory mechanotransduction complex that mediates touch sensation in Caenorhabditis elegans (O'Hagan, R., M. Chalfie, and M.B. Goodman. 2005. Nat. Neurosci. 8:43–50). They are members of a large family of ion channel proteins, collectively termed DEG/ENaCs, which are expressed in epithelial cells and neurons. In Xenopus oocytes, MEC-4 can assemble into homomeric channels and coassemble with MEC-10 into heteromeric channels (Goodman, M.B., G.G. Ernstrom, D.S. Chelur, R. O'Hagan, C.A. Yao, and M. Chalfie. 2002. Nature. 415:1039–1042). To gain insight into the structure–function principles that govern gating and drug block, we analyzed the effect of gain-of-function mutations using a combination of two-electrode voltage clamp, single-channel recording, and outside-out macropatches. We found that mutation of A713, the d or degeneration position, to residues larger than cysteine increased macroscopic current, open probability, and open times in homomeric channels, suggesting that bulky residues at this position stabilize open states. Wild-type MEC-10 partially suppressed the effect of such mutations on macroscopic current, suggesting that subunit–subunit interactions regulate open probability. Additional support for this idea is derived from an analysis of macroscopic currents carried by single-mutant and double-mutant heteromeric channels. We also examined blockade by the diuretic amiloride and two related compounds. We found that mutation of A713 to threonine, glycine, or aspartate decreased the affinity of homomeric channels for amiloride. Unlike the increase in open probability, this effect was not related to size of the amino acid side chain, indicating that mutation at this site alters antagonist binding by an independent mechanism. Finally, we present evidence that amiloride block is diffusion limited in DEG/ENaC channels, suggesting that variations in amiloride affinity result from variations in binding energy as opposed to accessibility. We conclude that the d position is part of a key region in the channel functionally and structurally, possibly representing the beginning of a pore-forming domain.

Touch, proprioception, and blood pressure regulation rely on mechanoreceptor neurons and mechano-electrical transduction (MeT) channels to convert mechanical cues into electrical signals. The protein partners that form native MeT channels are known only for a small group of mechanoreceptor neurons, including the touch receptor neurons responsible for gentle body touch in C. elegans. Such MeT channels are formed from at least four membrane proteins: two amiloride-sensitive sodium channel proteins (MEC-4 and MEC-10) and two putative lipid binding protein subunits (MEC-2 and MEC-6). It remains unknown how touch activates MeT channels, but interactions between the channel and the lipid membrane are likely to be essential. To learn more about interactions between MeT channels and specific lipids, we utilized C. elegans strains deficient in the synthesis of long-chain, poly-unsaturated fatty acids (PUFAs) and identified arachidonic acid (AA) as the sole PUFA required for full touch sensitivity. Touch receptor neurons retain normal morphology in PUFA-deficient mutants and normal touch sensitivity can be restored by exogenous PUFAs. We will present evidence garnered from behavioral and optogenetic studies suggesting that long-chain PUFAs are needed to activate native MeT channels, but dispensable for subsequent events linking sensory signaling in touch receptor neurons to behavior. Our data suggest that AA and its non-metabolizable analog ETYA directly modulate the activity of the MeT channel.