非均匀波导中的声聚焦

理论研究了声波在非均匀波导中的空间聚焦问题,利用多模态导纳法构建波导内任意位置处声压与入射声压在模态域的映射关系,计算使声波聚焦于空间某位置时的最佳入射波,并画出了相应的聚焦声场.研究了三种非均匀情况:水平变截面波导、含散射体波导以及声速垂直变化波导.结果表明,当输入最佳入射波时,在非均匀波导中可以产生良好的单点或多点声聚焦效果,声波的聚焦过程充分地利用了波导结构及介质非均匀性对声波的散射作用.     

Elastomeric Properties of Polysiloxane Networks. Bimodal Elastomers that are Spatially Inhomogeneous and Others that are Very Broadly Multimodal

End‐linking poly(dimethylsiloxane) was used to prepare bimodal elastomers networks so as to have inhomogeneous nanostructures, and also to prepare others having very broadly multimodal chain‐length distributions. Macroscopic phase separation, probably high crosslink density clusters, was observed to occur in some of the bimodal networks. The mechanical properties in simple extension and in equilibrium swelling were measured. The bimodal elastomers that were not obviously inhomogeneous showed very good mechanical properties, but the macroscopically phase‐separated networks, and the broadly multimodal network were weak. Analysis of the Mooney‐Rivlin profiles suggests that the reinforcing mechanism could have a structural component in addition to that from the limited extensibilities of the short chains. The mechanical properties and the extents of swelling support the cluster conjecture, in accord with previous morphological studies on spatially‐inhomogeneous polysiloxane elastomers.     

MOF-Derived Double-Layer Hollow Nanoparticles with Oxygen Generation Ability for Multimodal Imaging-Guided Sonodynamic Therapy

The high reactive oxygen species (ROS) generation ability and simple construction of sonosensitizer systems remain challenging in sonodynamic therapy against the hypoxic tumor. In this work, we rationally prepared MOF-derived double-layer hollow manganese silicate nanoparticle (DHMS) with highly effective ROS yield under ultrasound irradiation for multimodal imaging-guided sonodynamic therapy (SDT). The presence of Mn in DHMS increased ROS generation efficiency because it could be oxidized by holes to improve the electron–hole separation. Moreover, DHMS could produce oxygen in the tumor microenvironment, which helps overcome the hypoxia of the solid tumor and thus enhance the treatment efficiency. In vivo experiments demonstrated efficient tumor inhibition in DHMS-mediated SDT guided by ultrasound and magnetic resonance imaging. This work presents a MOF-derived nanoparticle with sonosensitive and oxygen generating ability, which provides a promising strategy for tumor hypoxia in SDT.     

多模态教学模式在“食品理化检验”中的应用

基于学生自主学习能力的培养,为更好地帮助并引导学生理解晦涩难懂、枯燥抽象的知识点,以我校卫生检验与检疫专业65名学生为研究对象,将食品理化检验课程的部分章节内容采用多模态教学模式,其余内容采用传统讲授教学模式,课程结束后使用统一问卷进行调查,对多模态教学效果进行评价。结果表明2种教学模式在理解抽象实验技术或仪器、活跃课堂气氛、拓宽学习思路以及培养学习兴趣、自主学习能力和解决实际问题能力等方面均有统计学差异(p＜0.05),且有95%的学生建议继续采用多模态教学模式。教学实践及其效果评价证明多模态教学对理解抽象问题等有一定的促进作用,并可唤起学生学习兴趣、培养学生解决实际问题的能力、拓宽学习思路等。     

Highly Mesoporous Metal‐Organic Frameworks as Synergistic Multimodal Catalytic Platforms for Divergent Cascade Reactions

Rational engineering and assimilation of diverse chemo‐ and biocatalytic functionalities in a single nanostructure is highly desired for efficient multistep chemical reactions but has so far remained elusive. Here, we design and synthesize multimodal catalytic nanoreactors (MCNRs) based on a mesoporous metal‐organic framework (MOF). The MCNRs consist of customizable metal nanocrystals and stably anchored enzymes in the mesopores, as well as coordinatively unsaturated cationic metal MOF nodes, all within a single nanoreactor space. The highly intimate and diverse catalytic mesoporous microenvironments and facile accessibility to the active site in the MCNR enables the cooperative and synergistic participation from different chemo‐ and biocatalytic components. This was shown by one‐pot multistep cascade reactions involving a heterogeneous catalytic nitroaldol reaction followed by a [Pd/lipase]‐catalyzed chemoenzymatic dynamic kinetic resolution to yield optically pure (>99 % ee) nitroalcohol derivatives in quantitative yields.     

Crowding with nearest neighbors replacement for multiple species niching and building blocks preservation in binary multimodal functions optimization

This paper introduces a novel niching scheme called the q-nearest neighbors replacement (q-NNR) method in the framework of the steady-state GAs (SSGAs) for solving binary multimodal optimization problems. A detailed comparison of the main niching approaches are presented first. The niching paradigm and difference of the selection-recombination genetic algorithms (GAs) and the recombination-replacement SSGAs are discussed. Then the q-NNR is developed by adopting special replacement policies based on the SSGAs; a Boltzmann scheme for dynamically sizing the nearest neighbors set is designed to achieve a speed-up and control the proportion of individuals adapted to different niches. Finally, experiments are carried out on a set of test functions characterized by deception, epistasis, symmetry and multimodality. The results are satisfactory and illustrate the effectivity and efficiency of the proposed niching method.     

晃荡

本文列举了诸多工程领域中的液体共振运动现象,详细探讨了船舱中伴有剧烈流动的晃荡问题.描述了基于理论分析的非线性多模态方法,该方法便于波动稳定性分区、多分支解和物理稳定性的研究.强调了方形舱、垂向圆柱舱以及球形舱内伴有旋转和混沌(不规则波动)的三维流动的重要性.晃荡引起的砰击涉及到各种各样的内流条件,这些条件随液体深度与舱体长度之比而变化.针对棱柱状LNG舱,讨论了许多与流体力学和热力学参数、影响砰击载荷效应的水弹性以及模型实验缩尺比的物理现象.     

具有区域极点约束的柔性梁鲁棒H∞振动主动控制

本文基于H∞控制理论研究了传感器和作动器非同位配置情况下,柔性悬臂梁的多模态振动抑制问题。采用频域辨识方法获取低阶名义模型,合理选取加性不确定权函数和性能权函数,将鲁棒H∞控制问题转化为标准H∞控制问题。为了避免H∞控制器设计过程中产生的零极点对消问题,在求解过程中引入区域极点约束。比较了鲁棒H∞控制器和不考虑高阶未建模动态的非鲁棒H∞控制器的控制效果,实验结果表明,设计的鲁棒H∞控制器能够有效抑制柔性梁的前三阶模态振动,而且不会发生溢出问题。     

Multifunctional Nano‐Bioprobes Based on Rattle‐Structured Upconverting Luminescent Nanoparticles

Lanthanide‐doped upconversion nanoparticles (UCNPs) have shown great promise in versatile bioapplications. For the first time, organosilica‐shelled β‐NaLuF₄:Gd/Yb/Er nanoprobes with a rattle structure have been designed for dual‐modal imaging and photodynamic therapy (PDT). Benefiting from the unique rattle structure and aromatic framework, these nanoprobes are endowed with a high loading capacity and the disaggregation effect of photosensitizers. After loading of β‐carboxyphthalocyanine zinc or rose Bengal into the nanoprobes, we achieved higher energy transfer efficiency from UCNPs to photosensitizers as compared to those with conventional core–shell structure or with pure‐silica shell, which facilitates a large production of singlet oxygen and thus an enhanced PDT efficacy. We demonstrated the use of these nanoprobes in proof‐of‐concept X‐ray computed tomography (CT) and UC imaging, thus revealing the great potential of this multifunctional material as an excellent nanoplatform for cancer theranostics.