Smooth functional and structural maps on the neocortex via orthonormal bases of the Laplace-Beltrami operator

Functional and structural maps, such as a curvature, cortical thickness, and functional magnetic resonance imaging (MRI) maps, indexed over the local coordinates of the cortical manifold play an important role in neuropsychiatric studies. Due to the highly convoluted nature of the cerebral cortex and image quality, these functions are generally uninterpretable without proper methods of association and smoothness onto the local coordinate system. In this paper, we generalized the spline smoothing problem (Wahba, 1990) from a sphere to any arbitrary two-dimensional (2-D) manifold with boundaries. We first seek a numerical solution to orthonormal basis functions of the Laplace-Beltrami (LB) operator with Neumann boundary conditions for a 2-D manifold M then solve the spline smoothing problem in a reproducing kernel Hilbert space (r.k.h.s.) of real-valued functions on manifold M with kernel constructed from the basis functions. The explicit discrete LB representation is derived using the finite element method calculated directly on the manifold coordinates so that finding discrete LB orthonormal basis functions is equivalent to solving an algebraic eigenvalue problem. And then smoothed functions in r.k.h.s can be represented as a linear combination of the basis functions. We demonstrate numerical solutions of spherical harmonics on a unit sphere and brain orthonormal basis functions on a planum temporale manifold. Then synthetic data is used to quantify the goodness of the smoothness compared with the ground truth and discuss how many basis functions should be incorporated in the smoothing. We present applications of our approach to smoothing sulcal mean curvature, cortical thickness, and functional statistical maps on submanifolds of the neocortex.     

Multi‐constrained Shortest Disjoint Paths for Reliable QoS Routing

Finding link‐disjoint or node‐disjoint paths under multiple constraints is an effective way to improve network QoS ability, reliability, and so on. However, existing algorithms for such scheme cannot ensure a feasible solution for arbitrary networks. We propose design principles of an algorithm to fill this gap, which we arrive at by analyzing the properties of optimal solutions for the multi‐constrained link‐disjoint path pair problem. Based on this, we propose the link‐disjoint optimal multi‐constrained paths algorithm (LIDOMPA), to find the shortest link‐disjoint path pair for any network. Three concepts, namely, the candidate optimal solution, the contractive constraint vector, and structure‐aware non‐dominance, are introduced to reduce its search space without loss of exactness. Extensive simulations show that LIDOMPA outperforms existing schemes and achieves acceptable complexity. Moreover, LIDOMPA is extended to the node‐disjoint optimal multi‐constrained paths algorithm (NODOMPA) for the multi‐constrained node‐disjoint path pair problem.     

基于非线性规划的链路丢包率推理算法

针对目前大多数链路丢包率推理算法不能兼顾精度和速度的问题,该文提出一种新的覆盖网链路丢包率推理算法,算法通过将链路丢包率推理问题转换为求解非线性规划的最优化解问题,从而较准确地计算出所有链路的丢包率。该算法仅需对每条端到端路径进行一次测量,且没有额外部署成本。通过软件模拟和Internet实验对算法性能进行了验证,实验结果证明了算法的可行性及优越性。     

PECVD法制备纳米晶硅薄膜的研究进展

简要介绍了纳米晶硅薄膜的微结构表征方法,重点讨论了PECVD制备方法中工艺参数对薄膜结构的影响,并探讨了氢在薄膜形成和生长中的作用。通过优化氢稀释率、衬底温度、反应气压、激励功率和激发频率等工艺参数可提高纳米晶硅薄膜的晶化率并改善薄膜质量。结合喇曼光谱、X射线衍射谱、傅里叶红外光谱和高分辨透射电镜等表征方法可深入研究薄膜形成机理,对进一步探索薄膜光电特性有重要意义。分析了等离子体化学气相沉积(PECVD)制备方法中各工艺参数对薄膜质量和沉积速率的影响,指出其存在的问题,并探寻了今后的研究方向。     

A Charge Reversible Self‐Delivery Chimeric Peptide with Cell Membrane‐Targeting Properties for Enhanced Photodynamic Therapy

The cell membrane is the most important protective barrier in living cells and cell membrane targeted therapy may be a high‐performance therapeutic modality for tumor treatment. Here, a novel charge reversible self‐delivery chimeric peptide C₁₆–PRP–DMA is developed for long‐term cell membrane targeted photodynamic therapy (PDT). The self‐assembled C₁₆–PRP–DMA nanoparticles can effectively target to tumor by enhanced permeability and retention effect without additional carriers. After undergoing charge reverse in acidic tumor microenvironment, C₁₆–PRP–DMA inserts into the tumor cell membrane with a long retention time of more than 14 h, which is very helpful for in vivo applications. It is found that under light irradiation, the reactive oxygen species generated by the inserted C₁₆–PRP–DMA would directly disrupt cell membrane and rapidly induce cell necrosis, which remarkably increases the PDT effect in vitro and in vivo. This novel self‐delivery chimeric peptide with a long‐term cell membrane targeting property provides a new prospect for effective PDT of cancer.     

Oxygen Vacancies Evoked Blue TiO2(B) Nanobelts with Efficiency Enhancement in Sodium Storage Behaviors

Oxygen vacancies (OVs) dominate the physical and chemical properties of metal oxides, which play crucial roles in the various fields of applications. Density functional theory calculations show the introduction of OVs in TiO₂(B) gives rise to better electrical conductivity and lower energy barrier of sodiation. Here, OVs evoked blue TiO₂(B) (termed as B‐TiO₂(B)) nanobelts are successfully designed upon the basis of electronically coupled conductive polymers to TiO₂, which is confirmed by electron paramagnetic resonance and X‐ray photoelectron spectroscopy. The superiorities of OVs with the aid of carbon encapsulation lead to higher capacity (210.5 mAh g^?1 (B‐TiO₂(B)) vs 102.7 mAh g^?1 (W‐TiO₂(B)) at 0.5 C) and remarkable long‐term cyclability (the retention of 94.4% at a high rate of 10 C after 5000 times). In situ X‐ray diffractometer analysis spectra also confirm that an enlarged interlayer spacing stimulated by OVs is beneficial to accommodate insertion and removal of sodium ions to accelerate storage kinetics and preserve its original crystal structure. The work highlights that injecting OVs into metal oxides along with carbon coating is an effective strategy for improving capacity and cyclability performances in other metal oxide based electrochemical energy systems.     

Field‐Induced n‐Doping of Black Phosphorus for CMOS Compatible 2D Logic Electronics with High Electron Mobility

Black phosphorus (BP) has been considered as a promising two‐dimensional (2D) semiconductor beyond graphene owning to its tunable direct bandgap and high carrier mobility. However, the hole‐transport‐dominated characteristic limits the application of BP in versatile electronics. Here, we report a stable and complementary metal oxide semiconductor (COMS) compatible electron doping method for BP, which is realized with the strong field‐induced effect from the K⁺ center of the silicon nitride (Si_xN_y). An obvious change from pristine p‐type BP to n type is observed after the deposit of the Si_xN_y on the BP surface. This electron doping can be kept stable for over 1 month and capable of improving the electron mobility of BP towards as high as ~176 cm² V^–1 s^–1. Moreover, high‐performance in‐plane BP p‐n diode and further logic inverter were realized by utilizing the n‐doping approach. The BP p‐n diode exhibits a high rectifying ratio of ~10⁴. And, a successful transfer of the output voltage from “High” to “Low” with very few voltage loss at various working frequencies were also demonstrated with the constructed BP inverter. Our findings paves the way for the success of COMS compatible technique for BP‐based nanoelectronics.     

星载红外探测器组件环境适应性分析与性能优选

为满足低等级红外探测器组件在高可靠性领域的空间应用需求,对星载红外探测器组件进行温度循环试验、力学试验以及高温老炼试验等环境试验考核,并基于双积分球式均匀照明系统对环境试验前后红外探测器组件相对光谱响应率进行测试。通过对比环境试验前后红外探测器组件相对光谱响应率变化,分析红外探测器组件的环境适应性,揭示红外探测器组件的质量缺陷及其他潜在缺陷,剔除早期失效,并从参试红外探测器组件中筛选出性能优良的探测器应用在星载偏振扫面仪进行大气偏振探测。试验结果表明:参试的红外探测器组件在环境试验前后具有良好的稳定性和可靠性,可以满足航天载荷应用需求。     

磁场中准二维强耦合磁极化子的性质

采用线性组合算符和改进的LLP变分法,研究了磁场中无限势垒量子阱内电子与界面光学声子强耦合、与体纵光学声子弱耦合系统的基态,得到了磁极化子的振动频率和自陷能随量子阱宽和磁场变化的规律.对CdF2/AgCl量子阱进行了数值计算,结果表明,磁极化子的振动频率和自陷能随阱宽的增加而减小,随磁场的增加而增大,但不同支声子与电子和磁场相互作用对磁极化子的振动频率和自陷能的贡献大不相同.此外,对以上现象进行了分析和解释.     

界面化学反应形成的纳米颗粒对有机交叉点存储器的影响

研究了有机交叉点存储器件中,有机物与电极界面化学反应形成的纳米颗粒对电学特征的影响.器件的阳极和阴极分别为氧化铟锡(ITO)导电玻璃和真空热蒸发沉积的～薄膜,有机半导体层为真空热蒸发沉积的2-amino-4,5-dicyanoimidazole(AlDcN)薄膜.通过透射电子显微镜(TEM)和X光电子能谱(XPS)测量,在AIDCN/ITO界面上发现SnOx纳米颗粒形成,并证明此纳米颗粒的形成是由于ITO中的高价氧化锡和AIDCN之间的固相反应,纳米颗粒中的Sn元素主要是从ITO表面的锡富集层中析出.研究证明了界面上纳米颗粒的形成是器件双稳态现象的关键,用这种方式制成的交叉点结构的三层有机存储器件其开关比达到107～1011.