The low-temperature dc conductivity and magnetoconductivity of ion-implanted ͑Ar ϩ ͒ and chemically doped ͑H 2 SO 4 ͒ polyaniline films have been studied. The metal-insulator transition has been observed for ion-implanted polyaniline films on increasing the irradiation dose to 3ϫ10 17 ions cm Ϫ2 . The maximum values of the room-temperature conductivity reached 800 S cm Ϫ1 for ion-implanted and 8 S cm Ϫ1 for chemically doped polyaniline films. In both cases, for samples on the insulator side of the metal-insulator transition, (T)ϭ͑0͒exp͓Ϫ(T 0 /T) m ͔, where mϳ0.5, whereas for the most heavily ion-implanted polyaniline films (T)ϳT at TϾ20 K; the minimum in the (T) occurs at Tϳ20 K and a negative magnetoconductance ⌬(H,T)ϳH 2 has been observed. It is shown that electron-electron Coulomb interactions play an important role in charge-carrier transport in ion-implanted polyaniline films near the metal-insulator transition.

Effectiveness of saline suspension of Corynebacterium pseudodiphtheriticum containing spray was assessed in a 30-days chamber experiment modeling the effects of hyperthermia and polluted air on humans. Spray was targeted at eliminating Staphylococcus aureus from the nasal cavity of human subjects. Three of four volunteers became S. aureus carriers in the course of the experiment, and one was a chronic carrier of methicillin-resistant S. aureus (MRSA). Spray application eradicated S. aureus in three subjects and reduced its presence in the MRSA carrier. Results of the study suggest that C. pseudodiphtheriticum can be used for control of S. aureus in the nasal environment. However, further investigations are required.

Silicon carbide has been used to fabricate a variety of short wavelength optoelectronic devices including blue LEDs, green LEDs and UV photodiodes. As a light emitter, 6H‐SiC junctions can be tailored to emit light across the visible spectrum. The most widely commercialized device is the blue LED. Over the past years, the quantum efficiency of the Cree Research blue LED has increased significantly. The devices emit light with a peak wavelength of 470 nm with a spectral halfwidth of ≈︂70 nm. The optical power output is typically between 25 and 35 μW at a forward current of 20 mA and 3.2 V. This represents an external quantum efficiency of ≈︂0.05 to 0.07%. Green LEDs have been demonstrated which emit with a peak wavelength of 530 nm. As opposed to the epitaxial junction used in the blue LED, the green devices use ion implanted junctions. The typical output power is similar to that of the blue LED. However, with respect to photometric units, the die luminous intensity is a factor of two higher than the blue LED, 1.2 mcd (millicandela) for a radiant flux output of 33 μW. In addition to short wavelength light emission, the energy bandgap of ≈︂3.0 eV allows for inherently low dark currents and high quantum efficiencies for ultraviolet photodiode detectors made in 6H‐SiC, even at high temperatures. These devices typically exhibit a quantum efficiency of 80 to 100% and peak response of ≈︂250 to 280 nm. These characteristics are maintained to at least 350 °C. The dark current density at —1.0 V and 473 K is ≈︂10—11 A/cm2. This corresponds to an extrapolated room temperature current density of ≈︂2 × 10—17 A/cm2 at —1.0 V.

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