一种超导重力仪磁悬浮力的等效计算

为实现超导重力仪磁悬浮力的精确计算,以GWR型超导重力仪为模型基础,采用有限元的思想,将超导球表面电流理想化为多个等高共轴电流环,计算出各个电流环与超导线圈的作用力,求和得到线圈与超导球间的磁悬浮力。利用MATLAB完成计算程序实现,通过改变下线圈电流和上、下线圈电流比,获得满足一定条件的磁悬浮力及其梯度。选取合适的模型参数,计算出线圈对质量为m=4.069 g超导球的磁悬浮力大小为:Ftotal=3.988×10^-2N,磁悬浮力梯度为:-9.699×10^-3N/m,此时悬浮力梯度合适,满足系统稳定性和灵敏度的要求。     

Quantifying non-Gaussianity via the Hellinger distance

Theoretical and Mathematical Physics - Non-Gaussianity is an important resource for quantum information processing with continuous variables. We introduce a measure of the non-Gaussianity of...     

The Crank–Nicolson finite spectral element method and numerical simulations for 2D non-stationary Navier–Stokes equations

In this paper, we first build a semi-discretized Crank–Nicolson (CN) model about time for the two-dimensional (2D) non-stationary Navier–Stokes equations about vorticity–stream functions and discuss the existence, stability, and convergence of the time semi-discretized CN solutions. And then, we build a fully discretized finite spectral element CN (FSECN) model based on the bilinear trigonometric basic functions on quadrilateral elements for the 2D non-stationary Navier–Stokes equations about the vorticity–stream functions and discuss the existence, stability, and convergence of the FSECN solutions. Finally, we utilize two sets of numerical experiments to check out the correctness of theoretical consequences.     

Take precautions against potential threats that carbon nanotubes may bring to you

Long-term pulmonary exposure to multi-walled carbon nanotubes (MWCNTs) may promote breast cancer metastasis and rapid colonization in the lungs and other organs according to recent research conducted by Prof.Chunying Chen,Prof.Tao Zhu and their colleagues,published in Nature Nanotechnology [1].     

Hydration-Facilitated Fine-Tuning of the AIE Amphiphile Color and Application as Erasable Materials with Hot/Cold Dual Writing Modes

Hydration water greatly impacts the color of inorganic crystals, but it is still unknown whether hydration water can be utilized to systematically manipulate the emission color of organic luminescent groups. Now, metal ions with different hydration ability allow fine-tuning the emission color of a fluorescent group displaying aggregation induced emission (AIE). Because the hydration water can be removed easily by gentle heating or mechanical grinding and re-gained by solvent fuming, rewritable materials can be fabricated both in the hot-writing and cold-writing modes. This hydration-facilitated strategy will open up a new vista in fine-tuning the emission color of AIE molecules based on one synthesis and in the design of smart luminescent devices.     

Rare-earth metal derivatives supported by aminophenoxy ligand: Synthesis,characterization and catalytic performance in lactide polymerization

A library of rare-earth metal derivatives supported by an aminophenoxy ligand was prepared and their catalytic performance in lactide polymerization was investigated. It was found that the synthetic strategy had a profound effect on the formation of aminophenoxy rare-earth metal complexes. Amine elimination between Ln[N(SiMe₃)₂]₃(μ-Cl)Li(THF)₃ (Ln = Yb, Y) and 1 equiv. of the aminophenol [HONH] ([HONH] = ο-OCH₃-C₆H₄NHCH₂(3,5-^tBu₂-C₆H₂-2-OH)) in toluene gave the unexpected heterobimetallic bis(aminophenoxy) rare-earth metal complexes [ON]₂LnLi(THF)₂ (Ln = Yb ( 1 ), Y ( 2 )). When the reactions were carried out in THF and TMEDA, amine elimination produced the aminophenoxy rare-earth metal amide complexes {[ON]LnN(SiMe₃)₂}₂ (Ln = Yb ( 5 ), Y ( 6 )) in ca 85% isolated yields. Complexes 5 and 6 could also be obtained from salt metathesis reaction of {[ON]LnCl(THF)}₂ (Ln = Yb ( 3 ), Y ( 4 )) with NaN(SiMe₃)₂ in a 1:2 molar ratio. In addition, treatment of complexes 3 and 4 with NaOAr (Ar = &bond;C₆H₄-4-^tBu) and (SiMe₃)₂NC(NPrⁱ)₂Na in 1:4 and 1:2 molar ratios provided the corresponding aminophenoxy rare-earth metal derivatives {[ON](μ-OAr)Ln(μ-OAr)Na(THF)₂}₂ (Ln = Yb ( 7 ), Y ( 8 )) and {[ON]Ln[(ⁱPrN)₂CN(SiMe₃)₂]}₂ (Ln = Yb ( 9 ), Y ( 10 )), respectively. These complexes were fully characterized, and their molecular structures were determined using single-crystal X-ray diffraction. Polymerization experiments showed that complexes 1 , 2 , 5 , 6 , 9 and 10 were highly active for the ring-opening polymerization of l -lactide in toluene, and complex 1 promoted l -lactide polymerization in a controlled fashion. The polymerization of rac-lactide initiated by the neutral aminophenoxy rare-earth metal complexes 5 , 6 , 9 and 10 in THF afforded heterotactic polymers.     

基于分子工程的方法设计首例具有Sr2Be2B2O7 (SBBO)结构的深紫外氟碳酸盐双折射晶体AMgLi2(CO3)2F (A=K,Rb)※

分子结构设计是开发新化合物和通过原子尺度操纵优化晶体结构的一种引人注目的策略. 在这个工作中, 利用分子工程的思想, 基于SBBO结构, 成功设计并合成两个新型氟碳酸盐KMgLi₂(CO₃)₂F和RbMgLi₂(CO₃)₂F. 在两个结构中, a-b平面是由CO₃和LiO₃F阴离子基团组成的无限[Li₃C₃O₆F₃]_∞层, 进一步相邻的层通过F原子连接形成一个独特的[Li₆C₆O₁₂F₃]_∞双层. 这种结构特征对改善晶体的层状生长习性和消除晶体的多晶性有很大的帮助. 光学测试表明, 该系列晶体具有大的双折射和短的紫外截止边, 是深紫外双折射晶体良好的候选材料.     

Hydroxyethyl cellulose-based electrically conductive,mechanically resistant,strain-sensitive self-healing hydrogels

Cellulose - Self-healing hydrogels that mimic human skin and have numerous senses of external tension and temperature are a current topic in science. However, getting skin-compatible performance...     

Surface modification boosts exciton extraction in confined layered structure for selective oxidation reaction

Science China Chemistry - Extracting photogenerated species from bulk to surface is an essential process for gaining efficient semiconductor-based photocatalysis. However, compared with charged...