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A series of acyclic nucleosides with two hydroxymethyl groups mimicking the 3'- and 5'-hydroxyl groups of the 2'-deoxyribose moiety were prepared and evaluated for their antiherpetic activity. Among those, 9-[[cis-1', 2'-bis(hydroxymethyl)cycloprop-1'-yl]methyl]guanine (3) showed extremely potent antiviral activity against herpes simplex virus type-1 (HSV-1) with good selectivity. Both enantiomers of 3 were synthesized starting from chiral epichlorohydrins, and only one of the enantiomers with 1'S,2'R-configuration (3a) exhibited strong antiherpetic activity (IC50 of 0.020 microg/mL against HSV-1 Tomioka vs 0.81 microg/mL for acyclovir). Enantiomer 3a was also more inhibitory than acyclovir against varicella-zoster virus (VZV) but ineffective against human immunodeficiency virus (HIV). Compound 3a is phosphorylated by HSV-1 thymidine kinase (TK) very efficiently. The relationship between conformation and antiherpetic activity in this series of compounds is discussed.

This paper reports on an investigation into the space charge formation and decay at different material interfaces. In particular, the influence of the interface between electrode and polymer or polymer and polymer on the space charge dynamics has been studied. Planar samples were subjected to high dc electric stresses for extended periods of time and space charge measurements taken using the pulsed ( ) electroacoustic PEA technique. It has been found that the types of interface between electrode and polymer play a significant role in determining the charge distribution in the insulation and that the interface between polymer and polymer acts as a potential barrier to electrons while allowing positive charge carriers through easily.Index Terms -LDPE insulation, insulation interface, space charge dynamics, PEA technique, effect of electrode materials, charge formation, charge decay, potential barrier.

We studied the trapping of positive and negative charges in the chemical structures of polymers under a high electric field using a space charge measurement system. Positive charges accumulated in low-density polyethylene (LDPE), whereas positive and negative charges accumulated in polyimide (Kapton ® ) and also in ethylene tetrafluoroethylene (ETFE) subjected to electron beam irradiation. To determine the charge-trapping sites in the chemical structures, a quantum chemical calculation was carried out using Density Function Theory (DFT) with Gaussian 09. The relationship between the energy band and the isosurface of orbital electrons at various energy levels was obtained. A threedimensional (3D) electrostatic potential distribution map was obtained for positively and negatively charged polymers to determine the relationship between a trapping site and the charge accumulation center in the 3D potential distribution map. Positive and negative charges in Kapton and ETFE films are trapped in trapping sites in chemical structures and the positive charges in an LDPE film are trapped in physical defects.

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