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Notes: Superconducting, silver-doped films of Y1Ba2Cu3O7−δ have been deposited by spray pyrolysis of aqueous nitrate solutions onto MgO substrates. The superconducting transport properties, microstructure, and microwave losses have been characterized for various amounts of AgNO3 added to the spraying solution. These films had resistive transition temperatures between 79 and 85 K with widths from 3 to 7 K. The room-temperature resistivity was a strong function of the silver doping, dropping by a factor of 50 for the heavily doped films. Critical current densities at 4 K were typically several 103 A/cm2 with little correlation to the silver doping. Lattice constants also were not significantly affected by the silver doping level, however, lightly doped films were denser, had the strongest c axis preferred orientation, and a smoother surface. Rf surface resistance was measured at 18 GHz, and for the best films dropped a factor of 10 below copper by 40 K. The London penetration depth was estimated to be approximately 1 μm for the best films.

Notes: We have studied the effects of light on high-temperature superconductor microstrip transmission lines under conditions for which a bolometric photoresponse is expected. We illustrate the pitfall of comparing a spatially local property (such as microwave detected photoresponse) and a global property (such as microwave transmission), and then drawing conclusions regarding the bolometric character of the photoresponse. For low microwave powers, the photoresponse, measured as function of the position of the spot illuminated, provides a measurement of the spatial inhomogeneity of the microwave properties of the film. For microwave powers large enough to depress the critical temperature, such measurements provide information about standing waves in the microstrip.

Notes: We report the first radiation effects study on a superconducting ring resonator made from thin-film YBa2Cu3O7−δ. Exposure to 2 MeV protons causes the superconducting transition temperature Tc to decrease predictably with fluence. For temperatures below about 0.9Tc , there is no significant change in the transmission coefficient, the center frequency, or the quality factor Q of the resonator, even for doses in excess of 4×1016 protons/cm2 (∼0.04 displacements per film atom). Similarly, the low-temperature surface resistance Rs of an unpatterned film does not change with irradiation. We show that this insensitivity to radiation is not predicted by standard theory, and that the dominant part of Rs at low temperature is the residual resistance R0. Thus any viable theory describing the origin of R0 must, as a criterion, explain the origin of its insensitivity to large irradiation doses. This criterion is used to evaluate theories ascribing R0 to weak links, flux pinning, impurities, and lattice imperfections.

Notes: Thin films of YBa2Cu3O7−δ were deposited on both sides of (100) LaAlO3 substrates by metalorganic chemical vapor deposition. Using a gold-coated wafer carrier, improvements in both the transition temperature and critical current density of the film exposed to the carrier (first side) were demonstrated. Tc's of 86–88 K and Jc's≥106 A/cm2 at 77 K were achieved. The microwave surface resistance of both sides of double-sided samples measured at 77 K was approximately 8 mΩ at 36 GHz, scaling to less than 700 μΩ at 10 GHz.

Notes: Thin films of YBa2Cu3O7−δ on (100) LaAlO3 and (100) SrTiO3, up to 5000 A(ring) thick, were grown by metalorganic chemical vapor deposition. The as-deposited films were c-axis oriented, and had transition temperatures between 87 and 89 K, transition widths less than or equal to 1 K, and critical current densities of 1–3×106 A/cm2 at 77 K. Microwave surface resistance measurements at 36 GHz on (100) LaAlO3 showed significant improvements over copper metal at 77 K. Films grown on (100) SrTiO3 exhibited slightly better properties than those grown on (100) LaAlO3. Films which were slightly deficient in barium and rich in yttrium consistently demonstrated superior properties.

Notes: Abstract Traditionally cervical dentinal sensitivity (CDS) has been evaluated mainly subjectively on the basis of the individual patient's subjective response, e.g., in the form of verbal rating and visual analogue scales and questionnaires. The stimuli used for evaluating this response can be grouped into 4 main categories: mechanical, chemical, electrical and thermal. This review of the literature, however, indicates that there are problems in evaluating patient subjective response to these various test stimuli used in the assessment and treatment of CDS. Opinions also vary as to the reliability of some of these methods of assessment, although recently, efforts have been made to develop controlled reproducible stimuli more suited to the evaluation of CDS. Currently no single method of eliciting and assessing CDS may be considered ideal. Further research is required to evaluate suitable methodology for the quantification of realistic test stimuli under controlled clinical conditions, whereby the subjective response may be objectively measured by the investigator.

Notes: Abstract 2 strontium chloride hexahydrate-containing dentifrices (SCH), similar except for their respective abrasive systems, were compared in a 2–month randomised double-blind parallel clinical study to evaluate their comparative effectiveness in terms of cervical dentinal hypersensitivity. 2 groups of 20 subjects, each with cervical dentinal hypersensitivity, were evaluated for tactile sensitivity by Yeaple probe, air sensitivity using a dental air syringe and subjective perception of pain by means of a visual analogue scale. There was no difference between the dentifrices as regards reduction of cervical dentinal hypersensitivity at each time point. The response to both dentifrices was evident within 4 weeks of use and the degree of improvement increased throughout the 8–week study period. The results support the conclusion that changing the abrasive component of SCH dentifrices did not significantly increase or decrease the (desensitizing) activity of the original product.

Notes: Abstract The aim of the present study was to evaluate possible associations between subgingival plaque bacterial morphotypes, as assessed by darkground microscopy, and clinical indices of routine adult chronic periodontitis. Clinical indices were plaque index (PII), gingival index (GI), sulcus bleeding index (SBI), papilla bleeding index (FBI), attachment loss (AL), pocket depth (PD) and probeable pocket depth (PPD). Apical border plaque was sampled in vivo and after extraction to test whether direct or indirect sampling affected any such associations. Similarly, pocket depth and attachment loss were also assessed directly and indirectly on the same teeth, in vivo or after extraction. The influence of the type of index used to record inflammation (GI, SBI, PBI) was also assessed, as were the effects of the numbers of sampled subjects and the method of analysis, which comprised the use of transformed and untransformed data and of parametric and non-parametric tests. Data were collected in relation to the approximal surfaces of 44 teeth extracted from 22 adults (2 teeth each) and from 1 pair of contralateral upper anterior or premolar teeth in each of 100 adults, all which untreated routine chronic periodontitis. Selected subjects had ≤4 mm probeable pocket depth and/or attachment loss, and radiographic evidence of bone loss in relation to 1 approximal surface on each of 1 pair of contralateral anterior or premolar teeth, or to 2 teeth scheduled for extraction. Plaque preparation and darkground microscopy were as described previously. Insignificant associations (P 〉 0.05) were demonstrated between supragingival plaque (P1I) and periodontal inflammation (GI, SBI, PBI) or destruction (PPD and AL), as well as between inflammation and attachment level. In contrast, significant moderate associations (r= 0.5–0.77) were demonstrated between each of the 3 morphotype groups; spirochaetes, other motiles and cocci. Spirochaetes showed a significant moderate (r= 0.5) positive association with pocket depth with a 2.43% mean increase of spirochaetes for each 1 mm increase of PPD. Although highly significant associations (r= 0.9) were demonstrable between the 3 inflammation indices (GI, SBI, PBI) themselves, only PBI showed significant positive associations (r= 0.3) with spirochaetes and other motiles. Also, P1I showed significant associations with each of the 4 morphotypes (r= 0.3–0.5). The heterogeneity of spirochaetes and other motiles as well as the multiplicity of possible aetiological microbial agents in plaque may have resulted in underestimated associations between subjects as well as undetectable association within a given mouth using only 4 morphotype groups. Method of plaque sampling, pocket depth, attachment loss or inflammation assessment did not generally affect the results. Nor did data transformation or statistical method used significantly enhance the strength of demonstrated associations.

Notes: Abstract A redox dye, methylene blue, was compared with subgingival root surface debridement and sterile water in the treatment of adult periodontitis. Plaque and gingival indices, bleeding on probing, and microbiological samples were obtained at baseline, and at 1, 4, 8 and 12 weeks following treatment. All subjects had matched pockets in each of the 4 quadrants, of 5 mm or more. One treatment consisted of 0.1% methylene blue gel irrigated professionally at 0, 1 and 4 weeks, and by subjects at days in between up to 4 weeks, at chosen sites within a randomly selected quadrant (split-mouth design). A 2nd treatment was sterile water irrigation as above. A 3rd quadrant received subgingival debridement, and sites in the 4th received methylene blue incorporated into a slow-release device of a biodegradable collagen alginate vicryl composite. All sites showed improvements in clinical and microbiological parameters. However, no statistically significant differences between treatment types were found for clinical measurements. Although plaque index tended to increase after week 1, gingival index was reduced, as was the papilla bleeding index. Probing depth reductions were approximately 1.2 mm for all treatments. Microbiological variables showed an increase in cocci and a decrease in motile organisms for all groups, the latter reaching statistical significance for subgingival debridement. The reductions in spirochaetes were significant for subgingival debridement and methylene blue by slow-release. Culture demonstrated an increase in the aerobe:anaerobe ratio for all groups, which was statistically significant initially (weeks 1 and 4) for subgingival debridement. Methylene blue was also effective statistically in improving this ratio, both by irrigation and slow-release (week 4). Methylene blue also significantly reduced the numbers of black-pigmented anaerobes during the trial period, both by irrigation and slow–release, which sterile water and subgingival debridement failed to do. No serious adverse experiences were seen, however, significantly greater morbidity was associated with subgingival debridement. These results clearly demonstrate that in altering the microflora to one that is more compatible with periodontal health, methylene blue treatment is comparable, or even better, than the currently standard treatment of subgingival debridement, and is better tolerated.