Role of water molecules in protein-nucleic acid interactions: visualization of a model highly hydrated complex structure of Inosine 5′-monophosphate and L-Serine (2C10H13N4O8P·C3H7NO3·12H2O) at atomic resolution

The crystal structure of a dodecahydrated co-complex between two Inosine 5-monophosphate (IMP) and one L-serine, the first of its kind reported, has been determined at atomic resolution by X-ray crystallographic methods. The crystal belongs to a monoclinic space group, P2₁, with the cell dimensionsa=8.695(7),b=21.898(6),c=12.374(3)Å, =110.59(3)°. This structure reveals the recognition mechanism of serine to the nucleotides through direct and water-mediated hydrogen bonds. The phosphate oxygen (O22) seems to prefer the nonspecific interaction with the functional sites of serine (N...O22=2.735, OG...O22=2.970, O1...O22 =3.121 Å), whereas the bases prefer specific (N17...N=3.199, N23...O2=2.784 Å) bondings. The solvent-mediated hydrogen bonds N17...W3...N27 endow extra stabilization to the stacked bases. The presence of hydrogen-bonded water spines and their interplay in the specific and nonspecific bindings with potential ligands indicate the functional involvement of solvent molecules through cooperative donor-acceptor network and could act as viable centers of intricate interactions in protein-DNA complexation processes.     

气相反应84/70 C_(70)(D_(5h))=C_(84)(D_2)热力学函数的计算

计算了不同温度下气相反应84／70C70（D5h）＝C84（D2）的热力学函数，讨论了C70（D5h）与C84（D2）之间相互转化的热力学条件；结果表明，温度低于2392K时C84（D2）比C70（D5h）稳定，温度高于2392K时气相中C70（D5h）比C84（D2）稳定；同时给出了气相C84（D2）的标准热力学函数。     

Ultrasonic-assisted environmentally-friendly synergetic synthesis of nitroaromatic compounds in core/shell nanoreactor: A green protocol

An efficient sonochemical protocol for the nitration of aromatic compounds was described in the presence of a catalytic amount of sulfuric acid-functionalized silica-based core/shell magnetic nanocomposite at room temperature in an eco-friendly and recyclable media, deep eutectic solvent (DES), based on choline chloride and urea. The particle size, morphology and elemental analysis of the core/shell nanocatalyst were carried out by TEM, SEM, EDX and XRD analyses. The nanocatalyst and DES were easily recovered from the reaction mixture quantitatively and reused several times.     

Cr(VI) oxidation using cetylpicolinium dichromate: Kinetics of oxidation of benzaldehydes with a green protocol

Oxidation kinetics of benzaldehyde and some of its ortho- and para-monosubstituted derivatives have been studied using cetylpicolinium dichromates, a class of novel phase transfer oxidants, in dichloromethane medium. The rate of reaction is first order with respect to oxidant and fractional order with respect to the substrates. The Michaelis–Menten type oxidation was observed with respect to the substrates. Benzaldehydes are found to be oxidized to their corresponding acids. The mechanism of oxidation reaction has been suggested based on the solvent isotope effect, Hammett plot, and thermodynamic study. The solvent isotope effect (k_CHCl3/k_CDCl3 = 1.57) indicates the involvement of hydrogen exchange with the medium during oxidation reactions. A strong influence of specific solute–solvent interactions on the rate of the reaction is observed. Both the electron-withdrawing and electron-releasing substituents on the substrates accelerate the rate of reaction.     

Efficient Green Protocol for the Synthesis of Novel Dihydroindeno[1,2-b]pyrroles

A simple and ecofriendly protocol has been developed for the expedient synthesis of novel dihydroindeno[1,2-b]pyrrol-4(3aH)-ones from the reaction of ninhydrin and (E)-N-methyl-1-(methylthio)-2-nitroethenamine or (E)-N-(1-(methylthio)-2-nitrovinyl)anilines.     

Hfinger: Malware HTTP Request Fingerprinting

Malicious software utilizes HTTP protocol for communication purposes, creating network traffic that is hard to identify as it blends into the traffic generated by benign applications. To this aim, fingerprinting tools have been developed to help track and identify such traffic by providing a short representation of malicious HTTP requests. However, currently existing tools do not analyze all information included in the HTTP message or analyze it insufficiently. To address these issues, we propose Hfinger, a novel malware HTTP request fingerprinting tool. It extracts information from the parts of the request such as URI, protocol information, headers, and payload, providing a concise request representation that preserves the extracted information in a form interpretable by a human analyst. For the developed solution, we have performed an extensive experimental evaluation using real-world data sets and we also compared Hfinger with the most related and popular existing tools such as FATT, Mercury, and p0f. The conducted effectiveness analysis reveals that on average only 1.85% of requests fingerprinted by Hfinger collide between malware families, what is 8–34 times lower than existing tools. Moreover, unlike these tools, in default mode, Hfinger does not introduce collisions between malware and benign applications and achieves it by increasing the number of fingerprints by at most 3 times. As a result, Hfinger can effectively track and hunt malware by providing more unique fingerprints than other standard tools.     

The epistemic gossip problem

In the gossip problem information (‘secrets’) must be shared among a certain number of agents using the minimum number of calls. We extend the gossip problem to arbitrary epistemic depths. For example, we may require not only that all agents know all secrets but also that all agents know that all agents know all secrets. We give optimal protocols for various versions of this epistemic gossip problem, depending on the graph of communication links, in the case of two-way communication, one-way communication and parallel communication. We show, among other things, that increasing epistemic depth from 1 (all agents know all secrets) to 2 (so that all agents know that all agents know all secrets) does not double the required number of calls but increases this number by $3∕2$ (for a complete graph). We also show that the following counter-intuitive result generalises to the epistemic gossip problem: asymptotically the same number of calls are required whether calls are two-way or one-way.     

Expandable quantum key distribution networks based on secret bits comparison

A scheme of quantum network based on multiuser differential phase shift quantum key distribution system (DPS-QKD) is proposed. In this quantum network, arbitrary two users can achieve secret bits sharing by point-to-multipoint quantum key distribution and secret bits comparison. A protocol of secret bits sharing between arbitrary two users is presented. This network can implement secret bits distribution over 200 km with higher key generation rate by today's technologies. In theory, the capacity of user numbers in this network is unlimited. Hence, our proposed quantum network can serve for a metropolitan QKD network. A wide area QKD network can be constructed with this metropolitan QKD network.     

Nonfragile dynamic output-feedback control for positive singular systems under the switched mechanism and Round-Robin protocol

In this paper, the singular positive system with uncertain parameters and switched structure is analyzed. First of all, a nonfragile dynamic output-feedback controller with Round-Robin protocol is constructed so as to decrease the occupancy of the communication channels and overcome the phenomenon of controller gain fluctuations. Then, the regularity, causality, positivity, and robustly exponential stability of the resultant closed-loop system are discussed respectively by utilizing the method of mode dependent minimum dwell time, mode dependent ranged dwell time, and mode dependent constant dwell time. The explicit design mechanisms of the related controller parameters are simultaneously presented. Finally, two simulation examples are provided to show feasibility of the theoretical results obtained.     

一种基于GMR-1 3G协议栈的自动测试方法

国际标准ISO/IEC9646定义了四种端系统抽象测试方法,其导出的测试框架无法满足第三代对地球同步轨道移动无线接口( Geostationary Earth Orbit Mobile Radio Interface,GMR-1 3G)协议栈测试关于实时性和跨平台性的要求。为了解决这一问题,对中科院提出的“钳形渡口测试法”进行研究,提出了基于GMR-1 3G协议栈的扩展“钳形渡口测试法”,并在实际的协议栈开发中得到应用。在总计与实时性相关的255个测试例执行中,测试通过率为100%。同时,由于利用统一测试框架和统一测试例脚本,既服务于仅有主机的协议逻辑流程测试又服务于仿真真实环境的板级测试,体现了较好的经济性。