摘要：化学取代是有效调节分子电导,产生多通道输运、量子干涉效应和其他机制的关键方法.但分子骨架和侧基之间存在复杂的相互作用,目前仍未被研究清楚.在本工作中,我们结合扫描隧道显微镜裂结实验技术和第一性原理计算方法,深入研究了具有不同σ和π侧基的分子电导.实验结果及理论分析表明,σ侧基的加入引起了分子前线轨道的对称性破缺并加剧了分子内散射,从而导致电导的降低.相反,π侧基引入了额外的电荷传输通道,实现了电荷传输的多通道效应,增加了分子的电导.这些发现为未来分子功能化和分子电子器件的设计提供了坚实的基础.

摘要：A storage system is the core of a computer,and plays an important role in the sustainable development of emerging strategic industries,such as artificial intelligence,big data,cloud computing,and the Internet of *** stack access is a major factor restricting the performance of data-intensive systems because of the increasing performance of processors and network devices.

摘要：Sweat could be a carrier of informative biomarkers for health status identification;therefore,wearable sweat sensors have attracted significant attention for *** external power source is an important component of wearable sensors,however,the current power supplies,i.e.,batteries,limit further shrinking down the size of these devices and thus limit their application areas and ***,we report a stretchable self-powered biosensor with epidermal electronic format that enables the in situ detec-tion of lactate and glucose concentration in *** biofuel cells serve as self-powered sensing modules allowing the sweat sensor to exhibit a determination coefficient(R2)of 0.98 with a sensitivity of 2.48 mV/mM for lactate detection,and R2 of 0.96 with a sensitivity of 0.11 mV/μM for glucose *** microfluidic channels developed in an ultra-thin soft flexible polydimethylsiloxane layer not only enable the effective collection of sweat,but also provide excellent mechanical properties with stable performance output even under 30%*** presented soft sweat sensors can be integrated at nearly any location of the body for the continuous monitoring of lactate and glucose changes during normal daily activities such as *** results provide a promising approach to develop next-generation sweat sensors for real-time and in situ sweat analysis.

摘要：The recent decade has witnessed an upsurge in the demands of intelligent and simplified Internet of Things(IoT)networks that provide ultra-low-power communication for numerous miniaturized *** the research community has paid great attention to wireless protocol designs for these networks,researchers are handicapped by the lack of an energy-efficient software-defined radio(SDR)platform for fast implementation and experimental *** SDRs perform well in battery-equipped systems,but fail to support miniaturized IoT devices with stringent hardware and power *** paper takes the first step toward designing an ultra-low-power SDR that satisfies the ultra-low-power or even battery-free requirements of intelligent and simplified IoT *** achieve this goal,the core technique is the effective integration ofµW-level backscatter in our SDR to sidestep power-hungry active radio frequency *** carefully develop a novel circuit design for efficient energy harvesting and power control,and devise a competent solution for eliminating the harmonic and mirror frequencies caused by backscatter *** evaluate the proposed SDR using different modulation schemes,and it achieves a high data rate of 100 kb/s with power consumption less than 200µW in the active mode and as low as 10µW in the sleep *** also conduct a case study of railway inspection using our platform,achieving 1 kb/s battery-free data delivery to the monitoring unmanned aerial vehicle at a distance of 50 m in a real-world environment,and provide two case studies on smart factories and logistic distribution to explore the application of our platform.

摘要：We are developing a compact rubidium atomic beam frequency standard with optical pumping and detection. The cavity for microwave interrogation is an important part of the clock. The cavity in our design is a Ramsey-type, E-bend one, which is the same as the conventional method in most cesium beam clocks. Requirements for the design are proposed based on the frequency shift associated with the cavity. The basic structure of the cavity is given by theoretical analysis and detailed dimensions are determined by means of electromagnetic field simulation with the help of commercial *** cavity is manufactured and fabricated successfully. The preliminary test result of the cavity is given, which is in good agreement with the simulation. The resonant frequency is 6.835 GHz, equal to the clock transition frequency of87 Rb, and the loaded quality factor is 500. These values are adjustable with posts outside the cavity. Estimations on the Ramsey line width and several frequency shifts are made.

摘要：In software-defined networking,the separation of control plane from forwarding plane introduces new challenges to network *** paper proposes a fault-tolerant routing mechanism to improve survivability by converting the survivability problem into two sub-problems:constructing an elastic-aware routing tree and controller *** on the shortest path tree,this scheme continuously attempts to prune the routing tree to enhance network *** a certain number of iterations,elastic-aware routing continues to improve network resiliency by increasing the number of edges in this *** results demonstrate this fault-tolerant mechanism performs better than the traditional method in terms of the number of protected nodes and network fragility indicator.

摘要：There are a lot of security issues in block cipher *** analysis and enhanced design of a dynamic block cipher was ***,the safety of ciphertext was enhanced based on confusion substitution of S-box,thus disordering the internal structure of data blocks by four steps of matrix ***,the diffusivity of ciphertext was obtained by cyclic displacement of bytes using column ambiguity *** dynamic key was finally generated by using LFSR,which improved the stochastic characters of secret key in each of round of *** safety performance of proposed algorithm was analyzed by simulation *** results showed the proposed algorithm has a little effect on the speed of encryption and decryption while enhancing the ***,the proposed algorithm has highly scalability,the dimension of S-box and the number of register can be dynamically extended according to the security requirement.

摘要：Lorenz 系统家庭统一 Lorenz 系统，陈系统和 L ü系统是一个典型混乱家庭。在这篇论文，我们与变化时间的推动间隔认为冲动的控制是 Lorenz 混乱系统家庭。由建立一套不平等的一个有效工具，我们分析冲动的控制 Lorenz 系统家庭的 asymptotic 稳定性并且获得一些新不太保守的条件。基于稳定性分析，我们与变化时间的推动间隔设计一个新奇冲动的控制器。解说性的例子被提供显示出我们的方法的可行性和有效性。获得的结果能不仅被用来为 Lorenz 系统家庭设计冲动的控制，而且能被扩大到另外的混乱系统。

摘要：In clinical magnetic resonance imaging （MRI）, the design of the radiofrequency （RF） coil is very important. For certain applications, the appropriate coil can produce an improved image quality. However, it is difficult to achieve a uniform B1 field and a high signal-to-noise ratio （SNR） simultaneously. In this article, we design an interventional transmitter-and-receiver RF coil for cerebral surgery. This coil adopts a disassembly structure that can be assembled and disassembled repeatedly on the cerebral surgery gantry to reduce the amount of interference from the MRI during surgery. The simulation results and the imaging experiments demonstrate that this coil can produce a uniform RF field, a high SNR, and a large imaging range to meet the requirements of the cerebral surgery.

摘要：Annular field aberrations of a three-reflection concentric system,which are composed of two spherical mirrors,are *** annular field with a high level of aberration correction exists near the position where the principal ray is perpendicular to the object-image *** are determined by the object height and aperture *** this letter,the general expression of the system aberration is derived using the geometric method,and the non-approximate design method is proposed to calculate the radii of the annular fields that have minimum aberrations under different aperture *** closer to 0.5（the ratio of the radius of convex mirror to the radius of concave mirror）is,the smaller the system aberration *** examples analyzed by LABVIEW indicate that the annular field designed by the proposed method has the smallest aberration in a given system.