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The new Heraeus STU fiber, which is very similar to the radiation resistant Russian KS-4V fiber, was subjected to [sup.60]Co gamma irradiation tests for the first time. The results of spectral measurements (300-850 nm) as well as of measurements at 829 and 1310 nm with different dose rates were compared with those of three 'radiation hard' fiber types. The STU fiber shows superior radiation hardness at high-dose values (>[10.sup.4] Gy), especially at about 1300 nm. Index Terms--High dose values, high radiation dose, optical fibers, radiation, radiation hard fiber.

It was proved that hydrogen ([H.sub.2]) treatment, consisting of loading with [H.sub.2] under high pressure and immediate pre-irradiation up to dose values [greater than or equal to][10.sup.4] Gy considerably increases the radiation hardness of optical fibers with a pure Si[O.sub.2] core, especially of those with a low OH content. These fibers even show a reduction of their initial attenuation at wavelengths Index Terms--Hydrogen treatment, optical fibres, radiation, radiation hardening.

This Letter reports the first, to the best of our knowledge, spectral radiation induced attenuation (RIA) measurements of nested anti-resonant nodeless hollow-core fibers (NANFs). A 5-tube NANF, alongside a solid-core single-mode radiation resistant fiber (SM-RRF), was irradiated under γ-ray up to 101 kGy (SiO 2 ) and under x-ray up to 241 kGy (SiO 2 ). No RIA was observed in the NANF in the second half of the O-band, the S-band, the C-band, and the L-band. The NANF showed a reduction of absorption bands associated with water and HCl under irradiation. Three new attenuation peaks were radiolytically induced and are attributed to the creation of HNO 3 . These peaks are centered respectively at 1441 nm, 1532 nm, and 1628 nm, with a full width at half maximum (FWHM) of, respectively, 10 nm, 12 nm, and 12 nm. These results demonstrate that the wide bandwidth range of NANFs is essentially unaffected by radiation, but the internal gas contents of the NANF must be managed to avoid producing undesirable spectral features through radiolytic reactions. Wide spectral regions almost unaffected by the ionizing radiation could open new possibilities for the use of NANF in harsh radiation environments.

Starting from polysomal RNA of developing maize endosperm and applying the cloning procedure of integrating dsDNA into the Pst I site of plasmid pBR 322, clones containing sequences complementary to endosperm mRNAs were obtained. 25 per cent of these clones were identified as containing zein specific DNA sequences which hybridized either with the zein mRNA coding for the 22 000 Mr protein or with the zein mRNA coding for the 19 000 Mr protein. The zein-specific DNA inserts of the recombinant plasmids were further characterized by restriction enzyme analysis.