On the existence theorem of non-trivial periodic solution of periodic systems of high order

In this paper, we consider nonlinear and nonautonomous systems with the trivial solution:dx/dt=f(t, x), x∈R~nwhere f(t+ω,x)+f(t, x), f(t, 0)=0. By using the theory of Brouwer topological degree, we obtainthe existence theorem of nontrivial ω-periodic solution. Finally the applied example of the theoremis cited.     

The consistencies ofMA,SOCA, OCA andISA withKT(ω2)

In this paper, we prove that ifZFC is consistent, then so are the following theories: $$\begin{gathered} ZFC + MA + KT(\omega _2 ) + 2^{\aleph _0 } = \aleph _2 , \hfill \\ ZFC + SOCA + KT(\omega _2 ), \hfill \\ ZFC + SOCA1 + KT(\omega _2 ), \hfill \\ ZFC + OCA + KT(\omega _2 ), \hfill \\ ZFC + ISA + KT(\omega _2 ), \hfill \\ \end{gathered} $$ whereMA denotes Martin's axiom.KT(ω ₂) the statement:“There exists anω ₂-Kurepa tree”, andSOCA, SOCA1,OCA andISA are axioms introduced in [1].     

Vibrational circular dichroism: a new spectroscopic tool for biomolecular structural determination

Vibrational circular dichroism (VCD) in the past two decades has developed into a powerful new structural tool. A concise review of the applications of VCD to determine the structures of various biological molecules, namely peptides and proteins, nucleic acids and carbohydrates, is provided.     

涂敷法制作质谱场电离发射丝的方法及性能研究

本文介绍一种新的质谱场电离发射丝的制备方法——涂敷法,并研究了其制备机理及影响发射丝灵敏度的因素。此外,还对涂敷法制作的发射丝及高温活化法制作的发射丝进行了各项性能对比试验。最后,介绍了涂敷发射丝的应用效果。     

Reversible polymerization driven by folding

Bisfunctionalized m-phenylene ethynylene imine oligomers were polymerized in the polar solvent acetonitrile, resulting in high-molecular weight poly(m-phenylene ethynylene imine)s. It is hypothesized that this polymerization, which proceeds through the reversible metathesis of imine bonds, is driven by the folding of the long m-phenylene ethynylene imine chains. Upon conducting the polymerization in a series of solvents in which the m-phenylene ethynylene oligomers exhibit different folding stabilities, it was possible to correlate the molecular weight of the resulting poly(m-phenylene ethynylene imine)s with the helical stability of the corresponding oligomers. The polymerization was also demonstrated to be reversible and responsive to solvent and temperature changes.     

Core/shell nanocomposite based on the local polarization and its electrorheological behavior

Aimed at the increase of electrorheological effect, a novel core/shell material was prepared by the combination of mechanochemical activity and sol-gel technique. The structure analyses X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, and energy-dispersive spectrometry showed that a modified kaolinite/titanium oxide nanocomposite consisted of the mechanochemically activated kaolinite/NaCl complex coated by titanium oxide. A distinct enhancement of the electrorheological activity was found by using such particles dispersed in silicone oil than those of kaolinite or titanium oxide alone under a direct current electric field. Modified kaolinite/titanium oxide electrorheological fluid has a larger dielectric constant enhancement deltaepsilon', and a strong interfacial polarization occurs with a clear dielectric loss peak around 2 kHz. Doping NaCl into the core (kaolinite) by the mechanochemical activation and limiting the transferring of the ions by the shell (titanium oxide) may increase the interfacial polarizability of particles and induce a high electrorheological effect.