N-Glycosylation represents an essential type of posttranslational modification for proteins. However, deciphering the functions of N-glycosylation remains a challenge due to the lack of analytical ...and biochemical methods to accurately differentiate the protein glycoforms with various intact glycans. Here we report our synthesis and evaluation of homogeneously glycosylated interleukin-17A (IL-17A), based on a synthetic approach combining solid-phase synthesis of (glyco)peptides, chemoenzymatic glycan modification on segments, and chemical ligations. The obtained homogeneous glycoproteins allow for the demonstration of the stabilizing role of N-glycans during the folding step. A comparison of three IL-17A glycoforms in a normal human dermal fibroblast (NHDF) assay reveals dose-dependent interleukin-6-inducing activities in all cases, wherein the glycoform with sialyl undecasaccharides displays much weaker stimulatory effect than that of the GlcNAc- or GlcNAc(β1→4)GlcNAc-modified proteins. Further surface plasmon resonance (SPR) and hydrogen/deuterium exchange mass spectroscopic experiments confirm that the evaluated complex type N-glycan impedes the binding between IL-17A and its receptor IL-17RA. This structure–activity relationship study on glycoproteins highlights the viability of applying the de novo approach to probe the roles of N-glycans.
Solid phase peptide synthesis（SPPS）based on Fmoc chemistry has become a commonly used technique in peptide chemistry,as it can be easily conducted using automated machine,and not requiring highly ...toxic HF in comparison to Boc-SPPS.With the fast development in the emerging field of protein chemical synthesis,many efforts have been endeavored aiming to find more efficient methods for preparing peptide fragments required in ligation reactions.This review briefly summarizes recent advances in the engineering and modification of Fmoc-SPPS-derived peptides,which can be used as the N-terminal fragments in a native chemical ligation（NCL）or NCL-type ligation reactions.
A smart hybrid nanowire array consisting of Co3O4 porous nanowire core and a MnO2 ultrathin nanosheet shell is fabricated using a general 3D interfacial carbon‐assisted hydrothermal method. The array ...exhibits a high capacitance with good cycle performance and remarkable rate capability that is ranging among the best reported to date for hybrid metal oxide systems in the absence of a conducting matrix.
In the process of preparing heavily doped silicon crystals for power electronics and solar power by the Czochralski(CZ) method, dislocations occur due to the presence of impurities and other factors. ...The presence of dislocations can affect the quality of single-crystal silicon crystalline columns. Therefore, we proposed the improved Yolov4-tiny model (Yolo-SPI) for detecting the occurrence of dislocations. For resolving the problem of low detection accuracy of the original model, we improve the neck part of the model by referring to the structure of the Path Aggregation Network (PAnet). Furthermore, we propose a feature enhancement module to improve the feature extraction ability of the model and introduce depthwise separable convolution to reduce the parameters. We produced the single-crystal silicon habit line dataset by using the industrial camera. The experimental results on our dataset show that the Yolo-SPI model outperforms Ghostnet-Yolov4, Mobilenetv3-Yolov4, EfficientDet-v0, and Nanodet. The Yolo-SPI model improves the Precision from 73.28% to 98.01% compared to the original Yolov4-tiny model and the Recall is also improved to 97.51%. At the same time, the number of parameters in the Yolo-SPI model is decreased from 5.87M to 2.05M compared to the Yolov4-tiny model. Our model also beats other models in the speed of detection, reaching 133FPS. In practical applications, our model achieves higher accuracy and faster detection speed.
Prolyl thioesters have shown significantly lower reactivities in native chemical ligation (NCL) in comparison to that of the alanyl thioester. This report describes a mild and efficient internal ...activation protocol of peptidyl prolyl thioesters in NCL without using any thiol-based additives, where the introduction of a 4-mercaptan substituent on the C-terminal proline significantly improves the reactivity of prolyl thioesters via the formation of a bicyclic thiolactone intermediate. The kinetic data indicate that the reaction rate is comparable to that of the reported data of alanyl thioesters, and the mechanistic studies suggest that the ligation of two peptide segments proceeds through an NCL-like pathway instead of a direct aminolysis, which ensures the chemoselectivity and compatibility of various amino acid side chains. This 4-mercaptoprolyl thioester-based protocol also allows an efficient one-pot ligation–desulfurization procedure. The utility of this method has been further demonstrated in the synthesis of a proline-rich region of Wilms tumor protein 1.
In this paper, a fast terminal sliding mode control (FTSMC) scheme with double closed loops is proposed for the spacecraft attitude control. The FTSMC laws are included both in an inner control loop ...and an outer control loop. Firstly, a fast terminal sliding surface (FTSS) is constructed, which can drive the inner loop tracking-error and the outer loop tracking-error on the FTSS to converge to zero in finite time. Secondly, FTSMC strategy is designed by using Lyaponov's method for ensuring the occurrence of the sliding motion in finite time, which can hold the character of fast transient response and improve the tracking accuracy. It is proved that FTSMC can guarantee the convergence of tracking-error in both approaching and sliding mode surface. Finally, simulation results demonstrate the effectiveness of the proposed control scheme.
•A fast terminal sliding mode control strategy is proposed for attitude control.•Also, it assures performances of fast response and high tracking accuracy.•A robust control law is employed to provide the complete compensation of disturbance.
This article analyzes the exponentially stable problem of neural networks (NNs) with two additive time-varying delay components. Disparate from the previous solutions on this similar model, switching ...ideas, that divide the time-varying delay intervals and treat the small intervals as switching signals, are introduced to transfer the studied problem into a switching problem. Besides, delay-dependent switching adjustment indicators are proposed to construct a novel set of augmented multiple Lyapunov-Krasovskii functionals (LKFs) that not only satisfy the switching condition but also make the suitable delay-dependent integral items be in the each corresponding LKF based on each switching mode. Combined with some switching techniques, some less conservativeness stability criteria with different numbers of switching modes are obtained. In the end, two simulation examples are performed to demonstrate the effectiveness and efficiency of the presented methods comparing other available ones.
The magnetic heterostructures provide flexible ways to realize particular magnetic properties that possess both scientific and practical significance. Here, by first-principles calculation, we ...predict strong Dzyaloshinskii–Moriya interactions (DMIs) by constructing CrI3/Metal heterostructures. The underlaying mechanisms are ascribed to the large spin-orbital coupling (SOC) of the I atom and the structural distortion in CrI3 layer caused by substrates. This is different from the traditional way that deposit magnetic films on substrate to generate DMI, wherein DMI is dominated by interlayer hybridization and large SOC of substrates. In addition, both Heisenberg exchange and magnetic anisotropy are modulated dramatically, such as Heisenberg exchange is nearly doubled on Au(111), and the out-of-plane magnetism is enhanced by 88% on Ir(111). Our work may provide a experimentally accessible strategy to induce DMI in layered magnetic materials, which will be helpful to the design of spintronics devices.
The landscape of cyber security has been reformed dramatically by the recently emerging Advanced Persistent Threat (APT). It is uniquely featured by the stealthy, continuous, sophisticated and ...well-funded attack process for long-term malicious gain, which render the current defense mechanisms inapplicable. A novel design of defense strategy, continuously combating APT in a long time-span with imperfect/incomplete information on attacker's actions, is urgently needed. The challenge is even more escalated when APT is coupled with the insider threat (a major threat in cyber-security), where insiders could trade valuable information to APT attacker for monetary gains. The interplay among the defender, APT attacker and insiders should be judiciously studied to shed insights on a more secure defense system. In this paper, we consider the joint threats from APT attacker and the insiders, and characterize the fore-mentioned interplay as a two-layer game model, i.e., a defense/attack game between defender and APT attacker and an information-trading game among insiders. Through rigorous analysis, we identify the best response strategies for each player and prove the existence of Nash Equilibrium for both games. Extensive numerical study further verifies our analytic results and examines the impact of different system configurations on the achievable security level.
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