ISSN:1044-8632    

DOI:10.1080/10448639708231979

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1044-8632    

DOI:10.1080/10448639708231980

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Radiation effect studies at IPNS have continued over the past five years at a relatively low but persistent level. Reduced from an initial facility consisting of a dedicated spallation target system optimized for radiation effects, the current program utilizes two thimbles in the Neutron Scattering Facility. One of the thimbles, located in the H2 beam line, is restricted to ambienttemperature irradiations; the second, located in Vertical Thimble 3, has been outfitted with a vacuum-isolated inner volume that permits irradiation at controlled temperatures up to 600T. This second thimble, called the Radiation Effects Module (REM), began operations in 1992. The energy required to achieve the desired temperature is supplied by electrical heaters on experimental inserts. Since the energy deposited in the thimble from the neutron and gamma fluxes is very low, temperature control in the thimble (independent of IPNS operation) is better than 1°C far superior to any other neutron irradiation facility. The REM is operated by the Materials Science Division at ANL, with experiments approved through the IPNS experimental review process.

ISSN:1044-8632    

DOI:10.1080/10448639708231981

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Kare-earth orihophosphates. RPO, (R = rare-earrh elements), are known for their outstanding properties. Their high melting temperatures (about 20OO0C), structural and chemical stability, and long-term corrosion resistance make these substances attractive for such applications as high-temperature components and nuclear waste storage media [1]. The optical properties of the rare-earth ions in RPO, hosts, particularly rareearth-activated luminescence, have found application in scintillators and phosphors. For example, in 1995, General Electric's lighting division introduced a new, long-life (10.000 h) household light bulb, known as the E-lamp [2]. It employs LaP0:Ce3+, Tb3+as green phosphors. The lamp produces 75-watt-equivalent light while consuming 23 watts of electrical power. Moreover, cerium-doped LuPO, has been found to be one of the most promising new scintillator materials [3]. The magnetic phase transitions and Jahn-Teller effects associated with some RPO, compounds also have prompted many fundamental investigations, as well as suggesting magnetic refrigerant applications.

ISSN:1044-8632    

DOI:10.1080/10448639708231982

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

A new class of antimicrobials, in the form of small polypeptides, has been recently discovered in host defense systems throughout the animal kingdom [1–3]. For example, magainins (23-residue polypeptide). secreted by the skin of the African clawed frog. and cecropins (31–38 residues) isolated from the humoral immune systems of insects [1,3] kill bacteria by permeabilizing the cytoplasmic membrane, but do not lyse eukaryotic cells [3]. The present understanding is that all these antimicrobials exert their activity directly on the lipid bilayer of the bacterial cellular membrane, rather than interacting with specific proteins in a cell like the conventional antibiotics. Hence, it is believed that bacteria may not develop resistance to these drugs, but the intriguing question that has to be addressed is, if these antimicrobials act on membranes, how do they selectively attack bacteria without harming the host cells?

ISSN:1044-8632    

DOI:10.1080/10448639708231983

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Zeolites represent an intriguing class of materials composed of infinite networks of silicon and aluminum atoms interconnected by oxygen atoms. The crystals of such materials often contain significant void space consisting of open cages and/or cylindrical pores. Aluminum and silicon are four-coordinate, which means in practice that charge-compensating cations are present in the void space to take into account the fact that aluminum is usually three-coordinate.

ISSN:1044-8632    

DOI:10.1080/10448639708231984

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1044-8632    

DOI:10.1080/10448639708231986

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1044-8632    

DOI:10.1080/10448639708231987

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

ISSN:1044-8632    

DOI:10.1080/10448639708231988

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor