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Noroviruses (previously Norwalk-like viruses) are the most common viral agents associated with food-and waterborne outbreaks of gastroenteritis. In the absence of culture methods for noroviruses, animal caliciviruses were used as model viruses to study inactivation by nonionizing (253.7-nm-wavelength [UV]) and ionizing (gamma) radiation. Here, we studied the respiratory feline calicivirus (FeCV) and the presumed enteric canine calicivirus (CaCV) and compared them with the well-studied bacteriophage MS2. When UV irradiation was used, a 3-log 10 reduction was observed at a fluence of 120 J/m 2 in the FeCV suspension and at a fluence of 200 J/m 2 for CaCV; for the more resistant phage MS2 there was a 3-log 10 reduction at a fluence of 650 J/m 2 . Few or no differences were observed between levels of UV inactivation in high-and low-proteincontent virus stocks. In contrast, ionizing radiation could readily inactivate MS2 in water, and there was a 3-log 10 reduction at a dose of 100 Gy, although this did not occur when the phage was diluted in high-proteincontent stocks of CaCV or FeCV. The low-protein-content stocks showed 3-log 10 reductions at a dose of 500 Gy for FeCV and at a dose of 300 for CaCV. The inactivation rates for both caliciviruses with ionizing and nonionizing radiation were comparable but different from the inactivation rates for MS2. Although most FeCV and CaCV characteristics, such as overall particle and genome size and structure, are similar, the capsid sequences differ significantly, making it difficult to predict human norovirus inactivation. Adequate management of UV and gamma radiation processes for virus inactivation should limit public health risks.Human caliciviruses are the most important enteric agents of gastroenteritis in industrialized countries (13,17). Many waterborne outbreaks associated with noroviruses have been reported (1,3,5,10,15). Usually, epidemiological data prove that water was the common source for the outbreak, and in some molecular tracing studies norovirus strains were successfully identified in the source water and identical sequences were found in stools from patients (4,8,11,12,16). Virus concentrations in source water may peak with sewage overflow due to heavy rainfall or leaking septic tanks or pipes (2, 20). Breakdown or malfunctioning of water treatment plants may lead to insufficient reductions in virus concentrations in drinking water (20). Moreover, European legislation is mainly based on bacteriological quality parameters that determine fecal contamination of food and water. Viruses, however, are more resistant to treatment (9), are generally harder to detect, and exhibit lower dose-response relationships than bacteria. Therefore, water may meet microbiological safety guidelines but still pose a considerable health hazard.Irradiation treatment is being used more frequently for disinfection of food and water. Bacteriophages have been used as indicators for inactivation of viruses by ionizing and nonionizing radiation since bacteria are generally less resista...

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La 1−x Li x MnO 3 (x=0, 0.1, 0.2, and 0.3) were synthesized by using conventional solid state reaction and partial melting technique. The compounds were determined to be of rhombohedral structure by x-ray powder diffraction. For the x=0.2 and x=0.3 samples, room temperature neutron powder diffraction patterns were collected and analyzed with the Rietveld method. The analysis showed that the Li substitutes onto the La site in the rhombohedral perovskite lattice. Resistivities were measured between 4.2 K and room temperature in the magnetic fields of 0, 1, 2, 4, 8, and 13 T. A wide semiconductor-metal transition at temperatures between 160 and 210 K or between 200–230 K were observed for both samples with x=0.2 and 0.3, respectively. Large magnetoresistances above 20%–80% were achieved at fields from null to 13 T over a wide temperature range from the ferromagnetic transitions down to 4.2 K. However, the x=0 and 0.1 samples show a semiconducting behavior in resistivity measured between 77 and 300 K.