JP3—1型示波极谱仪电源及显示系统的故障维修

本阐明了JP3—1型示波极谱仪电源及显示系统的工作原理，并举例说明这两部分的故障维修。     

Time‐resolved spectroscopy study of donor–acceptor‐type copolymers in a monodisperse system: The effect of ratio between the acceptor and the donor

The photoexcitation processes of two donor–acceptor‐type copolymers PCFBT with different ratios between the donor and the acceptor ( PCFBT_0.5 and PCFBT_0.1 ) in the solution system are systematically studied. If the number of the donor is equal to that of the acceptor in one repeat unit (such as PCFBT_0.5 ), intrachain charge transfer (ICT) can occur and participate in the relaxation of the excited state after photoexcitation. When the number of donors is much larger than that of acceptors (such as PCFBT_0.1 ) in one repeat unit, the ICT character can disappear, and the localized exciton decay process is dominant in the relaxation of the copolymer, which also involves an excitation intensity‐independent vibrational thermal relaxation process at the initial time. The results further the understanding of the basic structure‐property relationship. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 992–996     

Study on valence adjustment of Pu in 1?bp solution of CIAE-APOR process with N2O4

Oxidation of Pu(III) in 1 bp solution to Pu(IV) was studied using the salt-free oxidant N₂O₄. It was proved that the reductants N,N-dimethylhydroxylamine (DMHAN) and monomethyl-hydrazine (MMH) present in 1 bp solution of CIAE-APOR process can be oxidized and removed from the solutions also by N₂O₄ before the oxidation of Pu(III). The effects of the acidity, the temperature and the amount of N₂O₄ added on the oxidation of DMHAN and MMH were studied.     

Configuration and conformation of taibaihenryiin T isolated from <Emphasis Type="Italic">Phlomis umbrosa</Emphasis>

Taibaihenryiin T was isolated for the first time from Phlomis umbrosa Turcz, and its structure was elucidated on the basis of IR and NMR spectra analysis. Its molecular configuration, conformation, and crystal structure were also characterized by X-ray structure analysis. The infrequency of the C–O–O–C group is manifested in this molecular configuration, and hydrogen bonding assembles the molecules into a three-dimensional networking structure in the crystal.     

A study on melt grafting of maleic anhydride onto low‐density polyethylene and its blend with polyamide 6

Graft copolymerization of low‐density polyethylene (LDPE) with a maleic anhydride (MAH) was performed using intermeshing corotating twin‐screw extruder in the presence of benzoyl peroxide (BPO). The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were prepared in a corotating twin‐screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microcopy (SEM). The influence of the variation in temperature, BPO and MAH concentration, and temperature on the grafting degree and on the melt viscosity was studied. The grafting degree increased appreciably up to about 0.45 phr and then decreased continuously with an increasing BPO concentration. According to the FTIR analysis, it was found that the amount of grafted MAH on the LDPE chains was ～5.1%. Thermal analysis showed that melting temperature of the graft copolymers decreases with increasing grafting degree. In addition to this, loss modulus (E″) of the copolymers first increased little with increasing grafting and then obviously decreased with increasing grafting degree. Furthermore, the results revealed that the tensile strength of the blends increased linearly with increasing PA6 content. The results of SEM and mechanical test showed that the blends have good interfacial adhesion and good stability of the phase structure, which is reflected in the mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 267–275, 2010