Mechanical effects of acupuncture

Acupuncture, a physiotherapy, has been widely accepted all around the world. This study focuses on the influence of membrane structures and explains the acupuncture sensations from the aspect of mechanical properties. By mathematical modeling and numerical simulation, the scientific meaning of the acupuncture depth is investigated and phenomena and theory of acupuncture are discussed. The simulation results show that (a) the fascial structure is the main contributor to the force on the needle, the axial force will gradually increase before piercing the fascial, and suddenly decrease after piercing the fascial; (b) there is an inverse relationship between the needle radius and the maximum radial stress, which indicates that the needle should not be too sharp to cause local stress concentration and piece the fascia layer; and (c) the simulation results of comprehensively considering the static friction and sliding friction is identical with the experiment results. This study proposes a preliminary study of mechanical effects of acupuncture manipulation, clarifies key factors affecting the stress on the needle, and explains the objective requirement of acupuncture depth to effective treatment.     

Cascaded DNA circuits-programmed self-assembly of spherical nucleic acids for high signal amplification

Signal amplification is an important issue in DNA nanotechnology and molecular diagnostics. In this work, we report a strategy for the catalytic self-assembly of spherical nucleic acids(SNAs) programmed by two-layer cascaded DNA circuits through integrating an entropy-driven catalytic network, a catalytic hairpin assembly circuit, and a facile SNA assembly-based reporter system. This integrated system could implement ～100,000-fold signal amplification in the presence of 1 p M of input target.Possessing powerful amplification ability of nucleic acid signal, our strategy should be of great potential in fabricating more robust dynamic networks to be applied for signal transduction, DNA computing, and nucleic acid-based diagnostics.     

Efficient nitrate-to-ammonia transformation through a direct eight-electron reduction

Science China Chemistry -     

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.     

Dipolar Glass Polymers for Capacitive Energy Storage at Room Temperatures and Elevated Temperatures

Chinese Journal of Polymer Science - Dielectric polymers are the materials of choice for high energy density film capacitors. The increasing demand for advanced electrical systems requires...     

Assembly of ϵ-Keggin Polyoxometalate from Molecular Crystal to Zeolitic Octahedral Metal Oxide

Zeolitic octahedral metal oxides are inorganic crystalline microporous materials with adsorption and redox properties. New ϵ-Keggin nickel molybdate–based zeolitic octahedral metal oxides have been synthesized. ³¹P NMR spectroscopy shows that reduction of Mo^VI-based molybdates forms an ϵ-Keggin polyoxometalate that immediately transfers to the solid phase. Investigation of the formation process indicates that a low Ni concentration, insoluble reducing agent, and long synthesis time are the critical factors for obtaining the zeolite octahedral metal oxides rather than the ϵ-Keggin polyoxometalate molecule. The synthesized zeolitic nickel molybdate with Na⁺ is used as the adsorbent, which effectively separates C₂ hydrocarbon mixtures.     

In-situ cation exchange enhances room temperature phosphorescence of a family of metal-organic frameworks

The rational designability and chemical tunability of metal-organic frameworks(MOFs)are enabling tributes to efficaciously enhance their room temperature phosphorescence(RTP)performance.A family of stable anionic MOFs,[Zn₂(4,5-ImDC)₂]M₂(NKU-132,M=(CH₃)₂NH₂or(CH₂CH₃)₂NH₂),featuring significant RTP have been synthesized.By rational cation selection and in-situ replacement from dimethylammonium to diethylammonium,the phosphorescence lifetime is increased from 30.88 to126.3 ms,along with less sensitivity to air.This work provides an anti-quenching and lifetime tuning example for RTP-MOFmaterials via facile host-guest chemistry.     

Synthesis of CO2-based functional poly(carbonate-co-lactide)

TPPAlCl-PPN⁺Cl⁻ binary catalyst (where TPPAlCl is 5,10,15,20-tetraphenylporphyrin aluminum chloride, PPN⁺Cl⁻ is bis[triphenylphosphine] iminium chloride, the molar ratio of TPPAlCl to PPN⁺Cl⁻ is 1 to 0.5) can initiate the effective one-pot/one-step ternary copolymerization of CO₂, lactide and 4-vinyl-1-cyclohexene-1,2-epoxide, and the quaternary copolymerization of CO₂, propylene oxide, lactide, 4-vinyl-1-cyclohexene-1,2-epoxide, to form multiblock poly(carbonate-co-lactide) products with pendant vinyl group. The ternary copolymerization product composes of polylactide (PLA) block and poy(vinylcyclohexylene carbonate) (PVCHC) block, and the quaternary copolymerization product composes of poy(propylene carbonate) (PPC) block, PLA block and PVCHC block, which are verified by ¹H NMR, ¹³C NMR, ¹H-¹H cosy, hetero-nuclear multiple bond correlation, DTG, and Gel permeation chromatography analysis. The functionality and glass-transition temperature of the products can be easily adjusted by the copolymerization variables, such as the molar ratio of comonomers, copolymerization temperature, pressure of CO₂, the concentration of the catalyst.     

不同退火条件对PEALD制备的Ga2O3薄膜特性的影响

利用等离子增强原子层沉积技术(PEALD)在c面蓝宝石衬底上制备了氧化镓(Ga₂O₃)薄膜,研究了退火气氛(v(N₂)∶v(O₂)=1∶1(体积比)、空气和N₂)及退火时间对Ga₂O₃薄膜晶体结构、表面形貌和光学性质的影响。研究结果表明,退火前的氧化镓处于亚稳态,不同退火气氛下退火后晶体结构发生明显改变,而且退火气氛中N₂比例增加有利于Ga₂O₃重结晶。在N₂气氛下退火达到30 min,薄膜结构已由亚稳态转变成择优取向的β-Ga₂O₃。而且表面形貌分析表明,退火30 min后表面形貌开始趋于稳定,表面晶粒密度不再增加。另外实验样品在 400~800 nm的平均透射率几乎是100%,且光吸收边陡峭。采用N₂气氛退火,对于富氧环境下沉积的Ga₂O₃更利于薄膜表面原子迁移,以及择优取向Ga₂O₃重结晶。     

Terahertz Dual-Band Near-Zero Effective Index Metamaterial Based on Double-Sided Metal Microstructure

Journal of Russian Laser Research - The zero-refractive-index metamaterials have excellent electromagnetic properties, which provide new ideas and methods to realize the control of electromagnetic...