Performance characteristics of zig-zag optical path Nd:GGG slab lasers are reported. The sizes of the crystals are 6/sup t/ mm*10/sup w/ mm*100/sup l/ mm and 10/sup t/ mm*18/sup w/*167/sup l/ mm. These crystal slabs were polished with surface flatness of lambda /5 ( lambda =6328 AA), surface roughness of 8 AA rms, and surface parallelism of 10 s. In normal model oscillation, average output powers of 45 W were obtained with the smaller slab and 145 W with the larger slab. In Q-switched operation, an average output power of 11 W has been obtained, with a pulse width of 10 ns and repetition rate of 20 Hz. Long operating life has been also achieved by suppressing solarization of the Nd:GGG crystal with UV-cutoff filters placed in the pumping cavity.
An intensified UV imaging system covering the wavelength range 120 to 330 nm has been built and tested for space flight. A six-position fil-ter wheel divides the range into four narrow bands of interest, provides an ND1 filter for increased dynamic range, and provides a calcium fluo-ride window for maximum sensitivity and good rejection of Lyman al-pha. The optical path includes a reflective telescope, a cesium telluride image intensifier, a fiber-optic reducer, and a 380 by 488 pixel CCD sen-sor. The overall field of view is approximately 2.4° x 1.8°, with an angular spatial resolution exceeding 125 μrad. The system includes digitiz-ing electronics, associated memory, and a microprocessor-controlled AGC system. The maximum sensitivity of the system to a point source ex-ceeds 20 photons/cm2-s in the photon counting mode; with the use of the AGC and ND1 filter, the dynamic range exceeds 107.
The microbial populations within the media of a slow sand filter were evaluated with regard to distribution and activity. The filter that was investigated was one of ten filters providing water for Springfield, MA. Cores from the filter were used to quantify with depth acriflavine direct cell counts (AFDC) using epifluorescence microscopy, and nutritionally specific heterotrophs (R2A), aquatic organic matter (AOM) utilizers, benzoate utilizers, catechol utilizers, heterotrophic iron precipitators, and manganese oxidizers using various spread plate techniques. Extractable Fe and Mn, as well as Folin-reactive material (FRM) were quantified with depth. The ability of schmutzdecke populations to mineralize [U-14C] benzoate was also examined. AFDC counts revealed that the schmutzdecke contained the highest counts (109 to l010/g dry wt) with counts declining by one to two orders of magnitude with depth in the filter media. All nutritionally specific plate counts exhibited similar trends with depth; R2A plate counts were generally less than 1% of the AFDC. A significant percentage of the colonies on the R2A media were pigmented. AOM, benzoate, and catechol utilizers were more prevalent in the schmutzdecke (as a percentage of the AFDC) than with depth in the cores. Small, opaque-white colonies were observed on the AOM, benzoate, and catechol media; suggesting the same bacterium (small flagellated rod) was responsible for growth on the three media. FRM correlated well with the AFDC with depth; the data suggests that the Folin reagent complexed with bacterial aromatic amino acids and was thus a good measure of microbial biomass. Extractable Fe and Mn correlated with AFDC, FRM, and with heterotrophic Fe precipitator and Mn oxidizer plate counts. The data strongly suggest that extractable Fe and Mn is complexed to the bacterial biomass in the filter. All schmutzdecke samples were able to rapidly mineralize benzoate in the 1.0 to 1000 ng/ml range. Typically, over 50% of the label was converted to 14CO2 after 20 h of incubation. Mineralization was usually biphasic at 100 and 1000 ng/ml. Typical first order rate constants were 3 to 8/d. Non-purgeable dissolved organic carbon (NPDOC) removal in the filter was only 15%. Based on NPDOC and UV absorbance removals, the AOM fraction that was removed was hydrophobic and aromatic. The data suggests that while NPDOC removals are low, the microbial populations present in the filter are capable of promoting bioadsorption and biodegradation of certain fractions of the AOM in the raw water during winter operation.
Biplanar vacuum diodes, long used for the diagnostics of laser‐produced plasmas, have also been used as spectroscopic survey instruments for magnetically confined plasmas. The compact seven‐channel diode array, developed at KMS Fusion, provides broadband (ΔE/E≂1) channels of filtered cathodes to provide the spectral scan from 10 eV to about 5 keV (approximately 130 to 0.25 nm). Preliminary calibration results and calculations for a number of filters and cathodes are used to demonstrate that a satisfactory energy region may be obtained if an absorption edge of the cathode is below the mean energy of the desired channel and an absorption edge of the filter is above that energy. These devices are insensitive to neutron and gamma flux.
The design technique, fabrication, and breakdown-test results are described of a low-loss SAW (surface acoustic wave) filter for use in mobile telephone equipment. A multitransducer structure was adopted to get a low-loss SAW filter composed of 13 transducers (seven unapodized and six withdrawal) formed on a 36 degrees YX-LiTaO/sub 3/ substrate. As a result, the pass band loss was from 1.8 dB to 2.2 dB. Because the filter was for use in the UHF band (800 MHz band), the fingers of each transducer were required to be of a hyperfine line width. To form such a transducer on the substrate, it is useful to use lift-off technology using deep-UV exposure.
— We compared artificial UV‐sources such as germicidal‐ or sun‐lamps with summer noon sunlight in Switzerland for selective efficiency in the induction of pyrimidine dimers in the DNA of human cells. In our studies we determined cytosine‐thymine (C‐T) as well as thymine‐thymine dimer densities (T‐T) by high pressure liquid chromatography in cultures of xeroderma pigmentosum cells of group A. Using far‐UV light from a germicidal lamp, we found a rate of formation per Jirr2 for C‐T and T‐T of 0.0019% and 0.0024%, respectively, of the total thymine radioactivity in hydrolysates of [3H]thymidine labeled cells. After irradiation with an unfiltered sunlamp we measured a rate of formation of 0.0005% per Jm‐2 both for C‐T and T‐T, based on the sunlamp emission of 297 ±4 nm wavelength. Utilization of Kodacel‐ or Mylar‐filters lowered the rate of dimerization by a factor of 2 and 60, respectively. One hour of irradiation with noon summer sunlight induced 0.038 ±0.012% C‐T and 0.036 ±0.011% T‐T. This extent of dimer production is equivalent to 15 Jm‐2 of far‐UV exposure at 254 nm.
— Soybeans (Glycine max [L.] Men. cvs. Essex and Williams) were grown in an unshaded greenhouse under two levels of biologically effective ultraviolet‐B (UV‐BBE) radiation (effective daily dose: 0 and 11.5 kJ m‐2) for 34 days. Ultraviolet‐B radiation reduced leaf area and total plant mass in Essex but these parameters were unaffected in Williams. Differences in both anatomical and biochemical characteristics were found between cultivars. Some of these differences were inherently distinct between cultivars while others were variably induced by UV treatment. Specific leaf weight. an estimate of leaf thickness, was unchanged in Essex but increased in Williams with UV‐B irradiation. The relative increase in concentration of UV‐absorbing compounds in leaf tissues after UV‐B irradiation was greater in Williams. The composition of UV‐absorbing compounds in leaf tissues differed between the two cultivars but was unaffected by UV‐B radiation. Although total soluble proteins and total peroxidase activity were similar between cultivars, several electrophoretically distinct peroxidase activities were detected. Therefore, the intraspecific variation in UV‐B sensitivity found in soybean appears to be correlated with a suite of anatomical and biochemical differences, including leaf thickness, composition and concentration of UV‐absorbing compounds in leaf tissues, and possibly differences in peroxidase activities.
The photo-stability of nifedipine and its 4- or 1, 4-substituted derivatives in methanol was studied. A ferrioxalate actinometer was used to measure cumulative numver of photons as an index of light intensity. Under irradiation with a high-pressure mercury lamp, the photo-stability decreased in the order : l-hydroxy-4-(m-nitrophynyl) compound, 4-(p-nitrophenyl) compound, 4-(m-nitrophynyl) compound, l-methyl-4-(o-nitrophynyl) compound and nifedipine itself. The 4-phenyl compound and 4-(o-chlorophenyl) compound did not decompose in the range to 4×1021 quanta. Further, the photo-stability of nifedipine was quantitatively examined under sunlight, a fluorescent lamp and a high-pressure mercury lamp. The slopes of the linear plots of residual percent against cumulative number of photons irradiated through a UV-D33S colored glass filter were essentially the same for all three light sources. On the other hand, the slopes did not agree in the case of direct exposure without a filter. A good correlation between extent of photo-degradiation and integrated illumination (lux×h) was not observed with or without the filter. By means of this actinometry with a UV-D33S colored glass filter, the l-hydroxy-4-(m-nitrophenyl) compound and 4-(m-nitrophenyl) compound were quantitatively estimated to be more photo-stable than nifedipine by factors of 270 and 76, respectively, under a given light source.