你真的会玩翻身陀螺吗?

推导翻身陀螺在翻身过程中的角速度,解释为什么不怕速度太快而翻过头、翻身陀螺进动与自转方向"相反",以及并不是自转越快越易翻身.     

重力梯度力矩近似公式适用条件的探讨

教材中重力梯度力矩经典近似公式是基于常规尺寸空间结构推导的,如果直接应用于超大尺寸结构可能会导致精度不够、甚至错误的结果.以超大空间哑铃结构为研究对象,对比了基于重力梯度力矩非近似公式与经典近似公式得到的姿态动力学响应,指出了经典近似公式的局限性.通过提高重力梯度力矩中近似项的保留精度,提出了修正公式,并验证了该公式的适用性.所得结论是对重力梯度力矩教学内容的有益扩展,对工程应用也有帮助.     

梯度蜂窝面外动态压缩力学行为与吸能特性研究

蜂窝材料具有优异的抗冲击吸能特性.为进一步提高蜂窝材料的比吸能与压缩力效率,提出了一种几何参数或材料参数沿厚度方向梯度渐变的蜂窝材料模型,并针对六边形蜂窝构型研究了胞元壁厚和屈服强度梯度变化的蜂窝材料在面外动态压缩载荷下的力学行为与吸能特性.研究结果表明,通过调控梯度变化的指数,胞元壁厚或母体材料屈服强度的梯度设计均可有效降低初始峰值应力,并使蜂窝材料的比吸能和压缩力效率同时增大.研究结果可为蜂窝材料的防撞性优化设计提供新的思路.     

Keating改良模型的硅纳米梁动态特性

提出一种用于分析硅纳米梁动态特性的改良型半连续体模型,对比传统的连续体理论,这种新模型使用了Keating势,并考虑了纳米梁在宽厚两个维度的分立特性。依据Sun-Zhang模型思想和能量守恒定律,建立了改良型Keating模型,并进行了双端固支梁的基频计算。在这个过程中,对一些表面效应也进行系统分析。结果表明,该改良模型一方面在纳米尺度下与Material StudioTM软件仿真结果较为符合,另一方面也能在微观尺度下较好的接近连续体模型的计算数据。同时,该模型还反映了基频随纳米梁宽度变化的特性,这也符合一些实际实验。     

A Novel Aptamer-Imprinted Polymer-Based Electrochemical Biosensor for the Detection of Lead in Aquatic Products

Lead contamination in aquatic products is one of the main hazard factors. The aptasensor is a promising detection method for lead ion (Pb(II)) because of its selectivity, but it is easily affected by pH. The combination of ion-imprinted polymers(IIP) with aptamers may improve their stability in different pH conditions. This paper developed a novel electrochemical biosensor for Pb(II) detection by using aptamer-imprinted polymer as a recognition element. The glassy carbon electrode was modified with gold nanoparticles and aptamers. After the aptamer was induced by Pb(II) to form a G-quadruplex conformation, a chitosan-graphene oxide was electrodeposited and cross-linked with glutaraldehyde to form an imprint layer, improving the stability of the biosensor. Under the optimal experimental conditions, the current signal change (∆I) showed a linear correlation of the content of Pb(II) in the range of 0.1–2.0 μg/mL with a detection limit of 0.0796 μg/mL (S/N = 3). The biosensor also exhibited high selectivity for the determination of Pb(II) in the presence of other interfering metal ion. At the same time, the stability of the imprinted layer made the sensor applicable to the detection environment with a pH of 6.4–8.0. Moreover, the sensor was successfully applied to the detection of Pb(II) in mantis shrimp.     

HIMM回旋加速器控制系统中连锁保护功能设计与实现

在HIMM医用重离子加速器（Heavy Ion Medical Machine）中,回旋加速器的连锁保护功能针对离子源、高频、真空、电源、冷却水等子系统的连锁要求,设计实现了设备+PLC+软件三层结构的连锁系统,并保证连锁功能在系统断电、线缆连接故障、数据传输异常等情况下的正常工作。连锁系统可实现硬连锁毫秒级、软连锁次秒级别的反应速度。整体功能在回旋调试过程中得到验证,保障了整个加速器的顺利供束。     

Fluorination of Terminal Groups Promoting Electron Transfer in Small Molecular Acceptors of Bulk Heterojunction Films

The fluorination strategy is one of the most efficient and popular molecular modification methods to develop new materials for organic photovoltaic (OPV) cells. For OPV materials, it is a broad agreement that fluorination can reduce the energy level and change the morphology of active layers. To explore the effect of fluorination on small molecule acceptors, we selected two non-fullerene acceptors (NFA) based bulk heterojunction (BHJ) films, involving PM6:Y6 and PM6:Y5 as model systems. The electron mobilities of the PM6:Y5 and PM6:Y6 BHJ films are 5.76 × 10⁻⁷ cm²V⁻¹s⁻¹ and 5.02 × 10⁻⁵ cm²V⁻¹s⁻¹ from the space-charge-limited current (SCLC) measurements. Through molecular dynamics (MD) simulation, it is observed that halogen bonds can be formed between Y6 dimers, which can provide external channels for electron carrier transfer. Meanwhile, the “A-to-A” type J-aggregates are more likely to be generated between Y6 molecules, and the π–π stacking can be also enhanced, thus increasing the charge transfer rate and electron mobility between Y6 molecules.     

Natural Polyphenols for Treatment of Colorectal Cancer

Colorectal cancer (CRC) is a prevalent and serious gastrointestinal malignancy with high mortality and morbidity. Chemoprevention refers to a newly emerged strategy that uses drugs with chemopreventive properties to promote antioxidation, regulate cancer cell cycle, suppress proliferation, and induce cellular apoptosis, so as to improve cancer treatment outcomes. Natural polyphenols are currently recognized as a class of chemopreventive agents that have shown remarkable anticarcinogenic properties. Numerous in vitro and in vivo studies have elucidated the anti-CRC mechanisms of natural polyphenols, such as regulation of various molecular and signaling pathways. Natural polyphenols are also reportedly capable of modulating the gut microbiota and cancer stem cells (CSCs) to suppress tumor formation and progression. Combined use of different natural polyphenols is recommended due to their low bioavailability and instability, and combination treatment can exert synergistical effects, reduce side effects, and avoid drug resistance in CRC treatment. In summary, the application of polyphenols in the chemoprevention and treatment of CRC is promising. Further clinical evaluation of their effectiveness is warranted and anticipated.     

熔石英表面杂质元素在酸蚀过程中的变化

为了探寻熔石英表面痕量杂质元素种类以及随HF酸蚀刻过程中的变化情况,用质量分数为1%HF酸溶液对熔石英进行长达24,48,72,96 h的静态蚀刻实验。结合飞行时间二次离子质谱（TOF-SIMS）和X射线光电子能谱（XPS）测试分析结果发现,熔石英试片表面的痕量杂质元素主要含有B,F,K,Ca,Na,Al,Zn和Cr元素,其中绝大部分都存在于贝氏层中,在亚表面缺陷层检测到有K,Ca元素。所含有的K,Na杂质元素会与氟硅酸反应生成氟硅酸盐化合物。分析表明,在HF酸蚀刻的过程中一部分杂质元素将被消除,一部分杂质元素和生成氟硅酸盐化合物会随着蚀刻液逐渐从熔石英表面向表面纵深方向扩散并被试片吸附沉积,且随着深度的加深各元素的相对含量逐渐减少。     

羧酸类钕(Ⅲ) 配合物的合成、热稳定性和荧光性能研究

为了开发稀土有机配合物作为激光工作物质,分别以均苯三甲酸（H3BTC）、苯六甲酸（H6MTA）和1,2,3,4,5,6-环己六甲酸（H6CCA）为配体合成了三种Nd(Ⅲ)的二元发光配合物。通过元素分析、等离子体原子发射光谱和红外光谱对其化学组成进行了结构表征,确定其化学结构依次为Nd(BTC)4H2O,Nd2(MTA)6H2O和Nd2(CCA)4H2O,并对其热稳定性和荧光性能进行了分析测试。三种配合物的发射谱均有三个带状谱带,位于近红外区,其对应于Nd(Ⅲ)离子的特征跃迁4F3/24I9/2,4F3/24I11/2和4F3/24I13/2。结果表明,羧酸类钕(Ⅲ)配合物在近红外区具有明显的特征发射,具有良好的热稳定性和较好的发光性能,可以作为潜在的激光介质。