Lantibiotics: insight and foresight for new paradigm

Lantibiotics are a unique type of antimicrobial peptide produced by a large number of gram-positive bacteria that contain unusual amino acids, such as lanthionine and dehydrated amino acids. Ribosomally synthesized lantibiotic prepeptide consists of an N-terminal leader peptide followed by a C-terminal propeptide moiety that undergoes several post-translational modification events to yield a biologically active lantibiotic. Research on lantibiotics has drawn much attention in recent years and has undergone extensive progress as a step forward to the next paradigm. Unusual amino acids in lantibiotics solely contribute to their biological activity and also enhance their structural stability. Thus, enzymes involved in lantibiotic biosynthesis would have a high potential for peptide engineering by introducing unusual amino acids into desired peptides, which may establish a universal approach to advance the structural design of novel peptides, termed lantibiotic engineering. In this review, we focus on recent development with contemporary innovations and perspective of lantibiotic research.     

Cell properties for modified PTMA cathodes of organic radical batteries

Stable nitroxyl radical polymers, such as poly (2,2,6,6-tetramethyl-1-piperidinyloxy-4-yl methacrylate) (PTMA), are known to be effective as cathode active materials for lithium rechargeable batteries. A water-based slurry was used to prepare PTMA composite electrodes, enabling successful production of homogeneous electrodes. This improved utilization of active material and enabled us to obtain specific capacities almost equal to the theoretical value (111 mAh g⁻¹). Lithium half cells were fabricated using these electrodes and using graphite as the anode active material, and their cycling stability, temperature dependence, rate capability and self-discharge rate were measured in detail. Although they showed 24% irreversible capacity on the first cycle, the capacity stabilized after the second cycle.     

纤维的结构和性能（Ⅷ）

继续前报内容介绍高速纺丝Ｎｙｌｏｎ６纤维的结构和性能：密度随纺丝速度而变化，以有纤维的Ｘ射线衍射图像，晶型和力学性质。     

Microstructural Cause of the Peak Effect in Superconducting Y-Ba-Cu-O Melt-Grown Bulks

Superconducting Y-Ba-Cu-O bulks with J _c as high as 30 kA /cm ² (at 77 K and 1 T) containing both Y-123 and Y-211 phases were utilized in the present work . With different post-annealings, we obtained samples with different degrees of peak effect in the J _c -vs- H characteristics. Using specimens with TEM observable areas as wide as 20 × 20 (m) ² , large-area high-resolution transmission-electron-microscopic (LA-HRTEM) observations were made for the samples with different degrees of peak effect. Statistical analyses were made for the size of Y-211 particles and the distance between adjacent twin boundaries. It is revealed that (1) Y-211 particles including those of very small diameters have nothing to do with-the peak effect, while (2) the inter-twin-boundary distance is undoubtully correlated with the degree of peak effect. Further investigation on the twin boundary structure indicates that lower T _c regions may be formed in the vicinity of twin boundaries to provide fluxons with mesoscopically distributed weak pinning centers.     

纤维的结构和性能(Ⅰ)

本文是继纤维成形的第一篇“纺丝及纤维成形的机理”之后的第二篇“纤维的结构和性能”的第Ⅰ报.本报阐述了纺丝加工技术的进步和技术内容,并介绍了聚对苯二甲酸乙二酯(PET)的结晶,取向的基础概念和基本参数.     

Relative permittivity and conductivity of water‐treed region in XLPE estimated by an equivalent circuit

By dividing a water‐treed XLPE sheet sample of 1 mm thickness into a nondegraded region and a water‐treed one, relative permittivity and AC conductivity σ_AC2 of the water‐treed region have been estimated using an equivalent circuit. The variation of and σ_AC2 with the length r of the water‐treed region has been discussed based on the Sillars model. It was concluded that the volume fraction of water in the water‐treed layer is in the range from 0.5% to 1.5% for the most‐degraded XLPE sheet, which depends on the ratio of axes of spheroids to which water‐filled voids and channels are compared. It was also concluded that the AC conductivity of water in the water‐treed region ranges from 3 × 10^?3 S/m to 2 × 10^?2 S/m. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 7–14, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10332     

Measurement of incident position of hypervelocity particles on piezoelectric lead zirconate titanate detector

A cosmic dust detector for use onboard a satellite is currently being developed by using piezoelectric lead zirconate titanate (PZT). The characteristics of the PZT detector have been studied by bombarding it with hypervelocity iron (Fe) particles supplied by a Van de Graaff accelerator. One central electrode and four peripheral electrodes were placed on the front surface of the PZT detector to measure the impact positions of the incident Fe particles. It was demonstrated that the point of impact on the PZT detector could be identified by using information on the time at which the first peak of the output signal obtained from each electrode appeared.     

Total sputtering yields of solids under MeV-energy Si ion bombardment

Total sputtering yields have been measured for SiO₂ and Cu targets bombarded with Si ions at an incident energy between 500 keV and 5.0 MeV using a quartz crystal microbalance technique. In order to measure total yields accurately, we have developed a beam modulation technique to avoid the effect of thermal drift. In the MeV energy range, an ion penetrates through thin SiO₂ and Cu targets and is implanted into a quartz crystal. Therefore, the thickness of these layers deposited on quartz crystals was carefully controlled to avoid damage of quartz crystal by incident ions. As a result, total sputtering yields of SiO₂ increased with incident Si ion energy, while those of the Cu target decreased. The total yields of the SiO₂ target were represented well by a power low of the electronic stopping power.     

Synthesis and properties of optically functionalized polythiophene having porphyrin side-chain

The synthesis and photochemical properties of poly[1,3-bis(dithienyl)benzene] having a porphyrin group as a side-chain were studied. As a target monomer, 1,3-bis(dithienyl)benzene with an ethynylporphyrin substituent was synthesized by Pd-catalyzed cross-coupling reactions. The electrochemical polymerization of the monomer afforded a conductive polymer film on the ITO-coated glass. The spectroelectrochemistry of the polymer was investigated to clarify the electrochemical oxidation behavior. The current density of the target polymer showed a good photoresponse and the much larger photocurrent was observed as compared with the dark current.