Transformation of peptide nanotubes into a vesicle via fusion driven by stereo-complex formation

Two types of peptide nanotubes, one is prepared from an amphiphilic peptide having a right-handed helix segment and the other from that having a left-handed helix segment, are shown to transform the morphology into a vesicle by membrane fusion due to stereo-complex formation between these helical segments.     

Mechanism of enhancement in absorbance of vibrational bands of adsorbates at a metal mesh with subwavelength hole arrays

We have investigated the mechanism of enhanced absorption intensities of vibrational bands of adsorbates on copper meshes with subwavelength holes by measuring and simulating temporal profiles of infrared pulses transmitted through the meshes. As reported previously [Williams et al., J. Phys. Chem. B, 2003, 107, 11871], the absorption intensities of CH stretching bands of alkanethiolate adsorbed on the mesh increase substantially with decreasing hole size. The enhancements of absorption intensities are associated with temporal delays of infrared pulses transmitted through the mesh. Finite difference time domain calculations reproduce the observed pulse delays as a function of hole size. These facts indicate that the delays of transmitted pulses are not caused by coupling of infrared radiation to surface plasmon polaritons propagating on the front and rear surfaces of the mesh, but they are caused by the reduction in group velocity owing to coupling to waveguide modes of mesh holes. Consequently, the strong enhancements of the absorption intensities are attributed to adsorbates inside the holes rather than to those on the mesh surfaces that have been proposed previously.     

物理化学全线上教学的策略与实践

受新型冠状病毒肺炎疫情影响,学校的教学活动都转到线上进行。本文以天津大学"物理化学"课程为例,介绍了全线上教学的策略、过程设计与实施效果。通过进一步丰富线上教学资源、完善教学手段、实行全过程精细化管理,使得物理化学这门原本不太适合完全线上学习的课程,取得了满意的教学效果。学习过程中,学生的主体地位和教师的主导作用得以完美体现,获得的教学经验对于未来课程教学有很好的借鉴意义。     

Electrodeposition of Se on carbon-supported Pt nanoparticles by cyclic voltammetry

Cyclic voltammetry (CV) is a powerful and popular electrochemical technique widely used to study the surface structure of materials through the electrochemical behaviors. Herein CV is utilized to study the electrochemical deposition of selenium (Se) on carbon black-supported Pt nanostructures. We synthesized carbon-loaded platinum nanoparticles (Pt/C) by microwave method and studied the electrochemical behavior of selenium on them. Through the experiment of changing the reverse potential, the corresponding relationship between the Se deposition peak and stripping peak was clarified and the deposition and stripping process of Se was proposed. Meanwhile, we synthesized cubic and octahedral nanocrystals of Pt, and used CV to study the Se deposition on these nanosctructures supported by carbon. It was found that the relative intensity of UPD peaks on Pt is different, as Pt_cube@C is dominated by (100) and Pt_oct@C electrode is dominated by (111) while Pt@C falls in between.

     

Characterization of the supermolecular structure of cellulose in wood pulp fibres

The hierarchic organization of cellulose fibrils (microfibrils) was investigated in holocellulose, sulphite pulp and kraft pulp using TEM, XRD, ED and FTIR. There were remarkable differences in both the fibril structure and fibril aggregation between the samples. TEM observations revealed more intimately associated fibrils in the kraft pulp compared to the sulphite pulp and the holocellulose, results in agreement with previous CP/MAS ¹³C-NMR data [Hult E.-L. et al. (2002) Holzforschung 56: 231–234]. Furthermore, the cellulose crystallinity was higher in the kraft pulp sample. With respect to the cellulose I and I allomorphs, these samples were controversial when different analytical techniques were applied. Due to the small fibril size and the low degree of order of cellulose in these samples, the concept of crystalline triclinic and monoclinic components as determined by diffraction analysis may not be adequate. Instead the fibril can be regarded to have different degrees of lateral order (including paracrystalline ordering) that can be reoriented to I type conformation and packing upon pulping.     

Surface treatment of silicon carbide using TiO2(IV) photocatalyst

Silicon carbide (SiC) and diamond were decomposed to CO(2)(g) by the photocatalysis with TiO(2) at room temperature, although the decomposition rate of diamond was very slow. According to the XPS spectra of Si2p on the SiC surface, SiO(2) was simultaneously formed on the surface by the TiO(2) photocatalysis. The thickness of the SiO(2) formed on the SiC surface during the photocatalytic oxidation for 1 h was estimated to be about 40 A from the depth profile of the XPS spectra using Ar etching. The SiC surface was oxidized by the TiO(2) photocatalysis even under the condition without a direct contact with the TiO(2). This indicates that the photocatalytic oxidation of the SiC occurs due to active oxygen species photogenerated on the TiO(2) surface, but not by hole produced in the valence band of the TiO(2). Moreover, a remote surface treatment system using the quartz beads coated with TiO(2) was developed for the SiC surface oxidation. Consequently, the TiO(2) photocatalysis will be very useful for the surface treatment of SiC such as photopatterning without defects and damage to the substrate because the photocatalytic reaction is carried out under mild conditions.     

Alternating cooligomerization of isoprene and propylene with vanadium catalyst

Alternating cooligomerization of isoprene with propylene has been investigated between ?30 and 0°C, VO(acac)₂–Et₃Al–Et₂AlCl being used as catalyst. In the presence of an excess of propylene, 2,4,7-trimethyl-1,4-octadiene and 2,4-dimethyl-1,4-nonadiene are selectively formed. The formation is explained by the alternating coordination of isoprene and propylene to the vanadium. When triphenylphosphine or pyridine is added to the catalyst, the cooligomerization is suppressed while the formation of the dimer and trimer of isoprene is high.     

Analytic Bethe ansatz for fundamental representations of Yangians

We study the analytic Bethe, ansatz in solvable vertex models associated with the YangianY(X _r ) or its quantum affine analogueU _q (X _r ⁽¹⁾ ) forX _r =B _r ,C _r andD _r . Eigenvalue formulas are proposed for the transfer matrices related to all the fundamental representations ofY(X _r ). Under the Bethe ansatz equation, we explicitly prove that they are pole-free, a crucial property in the ansatz. Conjectures are also given on higher representation cases by applying theT-system, the transfer matrix functional relations proposed recently. The eigenvalues are neatly described in terms of Yangian analogues of the semi-standard Young tableaux.