Fine Mist Research Articles

Foliar uptake of wet-deposited nitrogen by norway spruce: an experiment using 15N

High rates of atmospheric nitrogen deposition have been shown to cause forest decline in some areas. A number of soil-mediated damage mechanisms are well-characterised but much less is known about the role of direct uptake of N by the canopy. The stable 15N isotope has been used in this experiment to quantify the assimilation of wet-deposited N by foliage and branches of 5 yr old Norway spruce trees. The effect of nutrient status (P and K) on N uptake was also investigated. Simulated rain solutions containing 99 atom% 15NH + 4-N or 99 atom% 15NO - 3-N at 15 mg N ℓ -1 were applied as a fine mist for 0.5 h. Woody twigs, current needles and current +1 year needles were sampled before and after misting and analysed for 15N enrichment and total N by automated mass spectrometry. All three tissue types showed some capacity for uptake of both 15NO - 3-N and 15NH + 4-N, although in nitrate treatments, N absorption was only statistically significant in woody twigs. Uptake rates were significantly higher in twigs compared with needles and in ammonium treatments compared with nitrate treatments, but only in PK fertilised trees. The concentrations of P and K in spruce foliage did not significantly affect the amount of N taken up by the canopy. Extrapolation of these data to mature forests suggests that foliar uptake is unlikely to exceed about 5% of annual N requirements, and will only make a small contribution to “N-saturation” of vegetation. The results of this experiment indicate that absorption of N by branches and twigs could potentially make an important contribution to total N requirements, although uptake may have been overestimated as it was not possible to differentiate between biological uptake of 15N and retention in the bark.

Surface Observation of the Er: YAG Laser Irradiated Restorative Alloys

Recently, the Er: YAG laser has been applied to some kinds of dental treatments. The aim of this study was to observe the surface changes of the restorative alloys irradiated by the Er: YAG laser. The specimens (8mm ∅×4mm high) were prepared from 5 alloys. [G;Type II gold alloy (CASTING GOLD M.C. TYPE II GC, Tokyo, Japan), 12% gold-silver-palladium alloy (PD; KINPARA S12% ISHIHUKU, Tokyo, Japan), silver alloy (S;MIRO 3, GC, Tokyo, Japan), amalgam (AM;SPHERICAL-D CAPSULE, SHOFU, Tokyo, Japan), gallium alloy (GA;Galliumalloy GF, Tokuriki, Tokyo, Japan)]. The specimens of G, PD and S were polished with silicon carbite paper to #1500. For AM and GA, two type of specimens were prepared [polished to #1500 (poAM, poGA), un-polished (noAM, noGA)]. The Er: YAG laser (KaVo K.E.Y. Laser) was irradiated to following 6 conditions: energy; 300mJ, pulse frequency; 1Hz, focal distance; 12mm, fine water mist; with/without, total pulse; 1, 3, 10 shots. The irradiated surface of specimens were observed using OPTIPHOTO (Nikon, Tokyo, Japan) and EPMA (Shimadzu, Kyoto, Japan). The results were as follows: 1. The Er: YAG laser irradiation did not affect G and PD. 2. S, poAM, noAM, poGA, noGA were melted by the Er: YAG laser irradiation. The surface of S was like beegum.The surface of poAM and noAM was crater form. The surface of poGA and noGA was like a thin film. 3. In cases of 10 shots irradiation to S, poAM, noAM, poGA, noGA and 3 shots irradiation to S and noGA, irradiation with the fine water mist spray caused more effect than irradiation without the fine water mist. In the other cases, the effects of fine water mist spray were little.

Ecogeography and breeding potential of the wild Peruvian tuber-bearing species ofSolanum

About 225 wild tuber-bearing species of Solanum occur on the American continent. Seventy-five percent of these are distributed in South America, with the largest concentration (approximately 100 species) occurring in Peru. Located on the western side of South America, Peru has five main regions: the Pacific Ocean Territory, the Coast, the Sierra, the Ceja de Selva, and the Selva. Wild potatoes are found only along the Coast, the Sierra, and the Ceja de Selva. The Coast (Fig. 1), a vast desert territory 2500 km long and 150 km wide, varies in elevation from sea level to 1000 m. The central and southern part of this region is usually covered with low clouds from April or May until October or November. When these clouds touch the mountains to the east, they produce a very fine condensation or mist called garua. This mist gives rise to a special ephemeral plant formation called the loma, which is notably lacking in species diversity. Within this coastal fog zone, the precipitation is extremely low, ranging from 4 to 80 mm of rainfall per year. Temperatures range from 13 to 23?C, and the humidity varies from 65 to 95 percent. During the winter season, some tuber-bearing species of Solanum occur in the lomas formation, including S. immite, S. medians, S. mochiquense, S. chancayense, S. neoweberbaueri and S. wittmackii. Not only are these species remarkable for their drought tolerance, but some are also quite resistant to viruses, fungi and bacteria. Solanum immite, for example, the first tuber-bearing species described for Peru by Dunal in 1852, is resistant to the spindle tuber viroid (PSTVd) and to the fungal wilt caused by a Verticillium species. Solanum medians, a coastal mountain species, has perhaps the widest distribution in the loma formations of the Peruvian coast. It is found from the Lomas de Manchay (350 m asl.) near La Molina, Lima (12?05' S and 76056' W) all along the southern Peruvian coast to the Lomas de Ilo (400 m asl.) and the Lomas de Sama (550 m asl.) in the departments of Moquegua and Tacna (or approximately 17?48' S and 70030' W). At Manchay-La Molina, the average annual precipitation is only 18 mm, while at Sama Grande it is 40 mm. The monthly median temperature for both places is 24?C and the minimum is nearly 13.5?C. Solanum medians represents a valuable source of genes for potato breeding programs. It is resistant to the attack of several potato viruses, including potato virus X (PVX), leaf roll (PLRV), potato viruses S (PVS) and M (PVM) and the potato spindle tuber viroid (PSTVd). It is also resistant to the tuber canker fungus, Synchytrium endobioticum; to the potato ring rot disease caused by the bacterium, Corynebacterium; the cyst nematode Globodera rostochiensis; and the tuber moth, Phthorimaea operculella. The most northern loma formation along the Peruvian coast is found at Cerro Campana (400 m asl.) in the vicinity of Trujillo (08005' S and 79?06' W). Here, thrives Solanum mochiquense, a species resistant to the potato black leg bacterium, Erwinia carotovora; the fungal organism, Synchytrium endobioticum; potato viruses PVS, and PVM; and, the nematode Meloidogyne. The Sierra divides the Coast from the Selva

Insecticide trials for control of the Autumn Gum Moth (Mnesampela privata), a primary defoliator in commercial eucalypt plantations prior to canopy closure

Summary The contact insecticides carbaryl, chlorpyrifos, fenthion, malathion and pyrethrins, the systemic insecticides dimethoate and omethoate, and the microbial insecticide dipel (Bacillus thuringiensis), were tested in an irrigated 2.8-year-old eucalypt plantation in north-central Victoria during mid-April 1996, at concentrations recommended by the manufacturers, and at twice and half those concentrations, for effectiveness in controlling the autumn gum moth Mnesampela private on foliage of Eucalyptus globules. The autumn gum moth is potentially a highly destructive feeder on juvenile leaves in up to 4-year-old plantations prior to canopy closure. Significant loss of growth, stunting and occasional tree mortality can be caused by severe attacks. Twenty-seven species of eucalypt are known to be variably susceptible. The tests were based on 25 treated trees plus an untreated ‘control’ tree, and on an examination of 234 infested leaves bearing 4832larvae, of which 98.7% were at the instar I to III stage, and the remainder at instar IV. Biological control caused only 3.6% mortality among the larval population. Aqueous sprays of 0.10% malathion, 0.0 I% pyrethrins or 0.25% chlorpyrifos, applied to foliage as a fine mist, caused a highly satisfactory 94.7 to 100.0% mortality among the larvae within two days. The concentrations for malathion and the pyrethrins conformed to recommendations by the manufacturers for controlling caterpillars (though not specifically the autumn gum moth), whereas the chlorpyrifos concentration was half of the concentration recommended against ants, cockroaches, silverfish and spiders. It appeared that the use of malathion is satisfactory at half the recommended concentration (i.e. at 0.05%) in areas where natural mortality of larval instars I-III of the autumn gum moth exceeds 10.0%. Chlorpyrifos was judged the least preferred option after malathion and the pyrethrins, on account of its higher mammalian toxicity, slow rate of degradation in soils and need to be registered for use against either caterpillars or the autumn gum moth in particular. Fenthion at 0.08, 0.04 and 0.02% concentration, omethoate at O.12, 0.06 and 0.03%, carbaryl at 0.2, O.I and 0.05%, dipel at 0.4, 0.2 and O.1% and dimethoate at 0.06, 0.03 and 0.015% caused insufficient mortality(< 66.9%) among larvae within 2 days of spraying to be recommended for use. Future research should examine higher concentrations of these insecticides (except of the highly hazardous omethoate) and different strains of B. thuringiensis (e.g. var. kurstaki (Foray 48B)), for effectiveness in controlling larval instars I to III of the autumn gum moth during mid-autumn, so that the choices for chemical control can be expanded.

Insecticide trials for control of the steelblue sawfly (Perga affinis affinis), a primary defoliator in young commercial eucalypt plantations of south-eastern Australia

Summary The contact insecticides carbaryl, chlorpyrifos, fenthion, malathion and the Pyrethrins, the systemic insecticides dimethoate and omethoate, and the microbial insecticide dipel (Bacillus thuringiensis), were tested in an irrigated 2.9 year-old eucalypt plantation in north-central Victoria during late May 1996 for effectiveness in controlling the steelblue sawfly (Perga affinis affinis) at concentrations recommended by the manufacturers against a range of target invertebrate pests, and at half and twice those concentrations. The steelblue sawfly, potentially a highly destructive ‘primary’ defoliator in young plantations up to several metres high, is known to attack 16 species of eucalypt, including E. camaldulensis and E. globulus, which are among the favoured species for commercial hardwood plantation programs in Australia. Upper crown foliage is particularly prone to damage between mid-winter and late-spring, although whole trees and entire stands can be stripped of foliage. Significant loss of height and diameter growth, stunting and occasional tree mortality can result, especially after repeated annual attacks. Large adult populations tend to build up where cool moist conditions prevail during spring and summer and where woodlands of susceptible species are nearby. The tests were based on 4 758 larvae, of which 33.3% were at the instar I stage, 64.8% at instar II and 1.9% at instar III on E. camaldulensis hosts. Biological control was not evident, and the experimental procedures used for handling, transport and storage had no adverse effects on the health of the larvae. Aqueous suspensions of 0.02% fenthion, 0.1% malathion and 0.01% Pyrethrins, applied to infested foliage as a fine mist, together with 0.1% chemspray wetting agent, caused a highly satisfactory 90.7 to 100.0% mortality among larvae within two days. They scored well against at least seven of nine desirable selection criteria, but malathion has the lowest hazard rating to human health; the Pyrethrins appear to be the least stable in the environment, and fenthion is the cheapest to spray. All three insecticides are presently not registered for use against the steelblue sawfly. Registration by the National Registration Authority for Agricultural and Veterinary Chemicals would be necessary if they were used in broadscale spraying during late autumn or early winter against early larval instars I to III. Omethoate at 0.12%, 0.06% and 0.03% concentrations, chlorpyrifos at 1.0%, 0.5% and 0.25%, and the high (0.06%) and recommended (0.03%) concentrations of dimethoate also induced very high larval mortalities (98.9% to 100.0%), but were rejected for use mainly because of their comparatively low LD50 (rats) values and other environmental concerns. The low concentrations of dimethoate, malathion and the Pyrethrins (0.015%, 0.05% and 0.005% respectively), and also the low to high concentrations of carbaryl (0.2%, 0.1%, 0.05%) and dipel (0.4%, 0.2%, 0.1%), caused insufficient mortality among larvae to be acceptable for application.

Misting of Tomato Plants Improves Leaf Water Status but not Leaf Growth

Field and laboratory experiments were carried out to determine whether modification of the aerial environment in a hot climate would improve the leaf growth rate and ultimately the yield of well- irrigated processing tomatoes, Lycopersicon esculentum Mill. cv. UC82B. In the field, the transpiration rate was modified by frequent applications of a fine mist. Misting reduced the diurnal fall in leaf water potential by up to 0.5 MPa, but had no effect on weekly vegetative growth or fruit yield, compared to a control treatment which was not misted but had accurately managed drip irrigation. To investigate these processes further, we studied the relationship between leaf water status and leaf growth in the laboratory using equipment in which a pot is placed inside a pressure chamber, with the leaves enclosed in a cuvette. Immediately following a misting event, both the hydrostatic pressure of the leaf xylem and the leaf expansion rate increased. The increase in leaf expansion rate was sustained for about 10 min and then fell below the pre-misted rate so that the net effect of a misting event on leaf expansion was small or nil. When an elevated leaf water status was sustained by pressurising the soil for over an hour, there was only a transient increase in leaf growth, and leaf growth stopped after the pressure was removed. Both in the laboratory and field, the overall leaf or vegetative growth was not sensitive to rapid fluctuations in leaf water status. The implication is that, if sufficient attention is paid to managing the root zone of crops, the more expensive and less efficient modification of the shoot environment is unnecessary.

Control of air toxin particulate and vapor emissions after coal combustion utilizing calcium magnesium acetate

Control of air toxin particulate and vapor emissions after coal combustion utilizing calcium magnesium acetate

Rotational particle separator: A new method for separating fine particles and mists from gases

AbstractAn account is given of the patented technique of the rotational particle separator for separating solid and liquid particles of diameter 0.1 μm and larger from gases. Attention is focused on the working principle, fluid mechanical constraints, particle design, separation performance, power consumption, dimensions, filter cleaning and costs. Furthermore, an overview is given of current developments to introduce this technique in industrial dust removal, in electricity generation and in the consumer goods market. The article concludes with a summary of the feature which distinguish this technique from existing filtering methods.

Thin Films of (Ba, Sr)TiO3 by Aerosol Combustion

AbstractBarium-strontium-titanate (BST) films were deposited on platinum-coated ceramic substrates and platinum foil by the aerosol combustion process. A fine mist of metallic precursors in solution was carried into a methane-oxygen flame to produce ceramic particles, which coated the substrate. Both aqueous and purely organic solutions were tested, the latter producing finer powders (less than 100 nm) with high phase purity. Sintering the as-deposited particulate material led to a porous film at all sintering temperatures studied, regardless of the solution used. Cold pressing of the organicsolution- based material prior to heating, without the addition of any binders or solvents, gave a fully dense solid after sintering at 1450°C.

Surface acoustic wave atomizer

Abstract An application of a surface acoustic wave device for miniaturization of ultrasonic atomizers and for functional system construction is proposed. Actually, ultrasonic atomizers are rather smaller than those produced by other methods, so that nebulizers that are handy to carry use ultrasonic vibration. However, they are too large for a pocket or a catheter. A fine mist has been obtained with the first trial of a surface acoustic wave atomizing device whose dimensions are pocket size. There is a possibility of this functional device being reduced to a system of millimetre size. The atomizer consists of a vibrator, a cover and a tube. The vibrator and cover material are 127.8° Y-cut LiNbO3 to generate a Rayleigh wave, a kind of surface acoustic wave. The Rayleigh wave is the driving force of the pumping and atomizing effects. The pumping effect is caused by the wave motion of the elastic material and viscosity of the fluid, like an ultrasonic motor. The atomizing rate varies according to the driving voltage. The maximum rate is about 0.6 ml min−1 at around 10 MHz. The linear mean diameter is 19 μm and the Sauter's mean diameter is 34 μm. A smaller device that operates at 47 MHz is also demonstrated.

Acetone Conversion in a Low-Pressure Oxygen Surface Wave Plasma

Destruction and removal efficiencies for acetone have been studied in a low pressure (4-8 Torr) oxygen plasma sustained at radio frequencies (rf) by surface waves. The solvent was introduced into the tubular reactor either as a vapor or as a fine mist using an ultrasonic nebulizer. The discharge was generated by a wave launcher external to the reactor tube, and product analysis consisted of on-line flame ionization gas chromatography techniques. Conversion efficiencies approaching 100% were achieved using low powers, millisecond-range residence times, and high solvent concentrations, without the need of the high temperatures required in thermal processes. The dependence of acetone removal on molar ratio, absorbed rf power, and pressure were studied in order to postulate possible reaction pathways and to discern the optimum discharge conditions to further improve destruction and removal efficiencies.

Venom spraying inParachartergus colobopterus: A novel defensive behavior in a social wasp (Hymenoptera: Vespidae)

Colonies ofParachartergus colobopterus do not defend against vertebrates by attacking and stinging. Instead, defending workers bend the gaster forward and spray a fine mist of venom in the direction of nearby moving objects. Although venom spraying has been reported forP. fraternus, a species that does sting, we found that this occurred only during sting attempts. We conclude that defensive behavior inP. colobopterus is unique among wasps in that (1) venom is sprayed at intruders by workers standing on the nest and (2) the spray is an atomized mist rather than a stream. We suggest that nest crypticity restricts vertebrate predators on this wasp to small, insect gleaning birds, against which a spray of venom in the eyes, mouth, and nasal passages is more effective than is a stinging defense.

Short-term transformation of applied 15NO 3− prairie and cultivated soils

Studies were undertaken to trace plant uptake and microbial transformation of applied NO 3 − on paired prairie and cultivated soils, Microplots (225 cm 2) in prairie and cultivated soils within the same soil map unit were treated with 26 mg 15NO 3 −N (22.36 atom% 15N) as KNO 3. The KNO 3 was applied as a fine mist to the soil surface with an atomizer. Plant tissue was removed and soil was excavated to a depth of 15 cm from the microplots after 24 and 72 h, Surface soils were assayed for total Kjeldahl N, and atom% 15N in total Kjeldahl N (including NO 3 −), NH 4 +, and NO 3 −. The subsurface soil, plant roots, and plant shoots were analyzed for total Kjeldahl N and atom% 15N. After 72 h about 75–83% of the applied 15NNO 3 − remained as N0 3 in the cultivated soil, whereas only 22–30% remained as NO 3 − in the prairie soil. At 24 h much of the 15N was found in the organic N pool in both prairie and cultivated soils, but by 72 h plant roots contained the greatest percentage of the immobilized 15NO 3 in the prairie soils.

Evaluation of greenhouse inoculation techniques to screen sorghum for resistance to downy mildew

Six inoculation techniques were compared for the artificial promotion of downy mildew (Peronosclerospora sorghi) in sorghum. These were (1) sprouted seeds incubated between sporulating infected leaves, (2) sprouted seeds depped in conidial suspension, (3) sprouted seeds sprayed with conidial suspension, (4) seedlings at plumule stage inoculated with drops of a conidial suspension, (5) seedlings at plumule stage sprayed with a conidial suspension, and (6) seedling showered with conidia falling from infected leaves. Seedlings at the one-leaf stage sprayed with a conidial suspension (6 × 105 ml-1) showed the highest systemic infection (100%) in the susceptible lines IS 643 and IS 18433. This technique is effective, repeatable, and allows the deposition of a conidial suspension as a fine mist on the entire seedling surface. In the greenhouse, the technique was used to test the downy mildew reaction of genotypes previously reported as resistant (< 5% incidence) in 3–4 years of field screenings. Of the 61 genotypes tested, 21 were free from downy mildew, 14 had less than 5% incidence, and the rest showed variable susceptible reactions. Therefore, the technique can be reliably and effectively used in the greenhouse to detect disease escapes and to indentify resistance.

Discussions on the use of fine water sprays or mists for fire suppression

Abstract Recent experimental work on fine water sprays indicates that they may have a wider application in the fields of fire extinction and combustion suppression than previously anticipated. In this paper, the means of producing fine sprays are briefly examined and the major results of some case studies are reviewed. A few unexpected positive results have come to light, especially with regard to using fine mists to protect against fires involving live electrical equipment. However, it is still premature to advocate the use of fine sprays for many applications.

Dispersal of soredia from individual soralia of the lichen Hypogymnia physodes (L.) Nyl. in a simple wind tunnel

Dispersal of soredia from individual soralia of the lichen Hypogymnia physodes (L.) Nyl. was studied using a simple wind tunnel constructed in the field. Individual lobes with terminal soralia were placed in the wind tunnel on the adhesive surface of dust particle collectors. Air currents produced by a fan were directed over the surface of the lobes. The majority of soredia were deposited within 5 cm of the source soralium but some soredia were dispersed to at least 80 cm at a wind speed of 6 m s −1. Variation in wind speed had no statistically significant effect on the total number of soredial clusters deposited averaged over soralia but the mean size of cluster and the distance dispersed were greater at higher wind speeds. The number of soredia deposited was dependent on the orientation of the soralium to the air currents. More soredia were deposited with the soralium facing the fan at a wind speed of 9 m s −1. Moisture in the form of a fine mist reduced substantially the number of soredia deposited at a wind speed of 6 m s −1 but had no effect on the mean number of soredia per cluster or on the mean distance dispersed. The data suggest: (1) that wind dispersal from an individual soralium is influenced by wind speed, the location of the soralium on the thallus and the level of moisture and (2) that air currents directed over the surfaces of thalli located on the upper branches of trees would effectively disperse soredia of H. physodes vertically and horizontally within a tree canopy.

Decreasing the impact of surface crusting on seedling: emergence by spray wetting

Abstract. . A soil crust, produced by applying 44 mm of distilled water at an intensity of 290 mm/h using a rainfall simulator, was sufficiently rigid to significantly decrease emergence of barley from 76 to 40% and of oil seed rape from 82 to 61%. If the crust was kept wet by regular application of water as a fine mist, its strength was significantly decreased, but emergence remained poor because of prolonged soil wetness. After mist‐spraying the crusted surface just before emergence, per cent emergence was greater than uncrusted controls.Application to the soil of a static pressure after sowing but without crusting either had no effect or increased emergence, probably because of improved seed‐soil contact. However, crusting of the compacted soil decreased emergence severely. If the crust was allowed to dry it became very strong (&gt; 300 kPa). Mist‐spraying at the time of emergence only also improved seed emergence almost to that in the uncrusted controls. Repeated mist spraying after crusting decreased the strength of the crust, but the resulting waterlogging decreased emergence to less than half those of the controls and of the treatments sprayed just before emergence only. Compared with other management techniques available for amelioration of crusted seedbeds, carefully timed fine spray watering seems to offer the best opportunity for ensuring rapid seed emergence comparable to that in uncrusted soils.

Improvement of the analytical performance of the FAAS method by hydraulic high pressure sample introduction

The hydraulic high pressure nebulization (HHPN) system is a totally new and effective sample introduction method in atomic spectrometry. The liquid sample is forced through a special nozzle with high pressure (5–40 MPa) generated by an HPLC pump. The nozzle involves a Pt-Ir plate with an orifice of 10–30 μm through which the constant flow (1–3 ml/min) of high pressure liquid produces a fine mist. The aerosol yield is more than 50%. The analyte solution is introduced with a probe feed valve through a sample loop into the high pressure solvent stream and passes along with the transport medium (water, organic solvent) to the nebulizing nozzle. This new sample introduction system was coupled with a flame atomic absorption spectrometry (FAAS) instrument to investigate the improvement of analytical performance compared to conventional pneumatic nebulization. As a consequence of the improved aerosol yield of HHPN, the sensitivity of FAAS is increased by factors of 2–3 and 6–8 on the basis of peak height and peak area of the transient analyte signal, respectively. The long-term (1–3 h) stability of the system is excellent. The RSD in the normal analytical working range is 1–2%, depending on the element. The droplet size distribution of aerosols produced by pneumatic and nebulization HHPN has been measured. In the case of HHPN the smaller droplet size explains the moderated matrix effect of 10–30% NaCl on the determination of Co, Cu, Mn, and Ni. In FAAS one of the advantages of HHPN sample introduction is the analysis of highly concentrated and viscous solutions. Many elements (e.g., Cr, Cu, Mn, Mo, V) have been quantified as traces in saturated pro analysi suprapure chemicals (2% LiBO 2, 10% KH 2PO 4, 20% SbCl 3 in 24% HCl, 30% NaCl, 50% MgSO 4 · 7H 2O, 60% Co(NO 3) 2, 85% H 3PO 4) and highly salted waste waters. Solutions were introduced without any difficulties because their higher viscosity was automatically compensated by the flow rate-regulated high-pressure pump. On the other hand, pneumatic nebulization of these samples was difficult or in some cases totally impossible.

A new approach for insulin delivery via the pulmonary route: Design and pharmacokinetics in non-diabetic rabbits

A mini-mist medication air compressor fitted nebulizer was used to deliver insulin in the form of a fine mist via the rabbit's pulmonary system. An insulin immune test was first performed in order to ensure the rabbit's respiratory compliance and then the bioavailability was examined as a function of insulin dose concentration and dose volume. An increase in dose concentration from 2 to 5 U kg − rbw was found to reduce the percentage minimum plasma glucose concentration (%MPGC) from 71 to 38% without affecting the time T required to attain these values (i.e., T%MPGC = 20 min). The values of the percentage total reduction in plasma glucose from 0 to 3 h (%TRPG 0–3h) were also found to increase from 15 to 37% as insulin concentration increased. On the other hand, an increase in dose volume from 1 to 3 ml did not lead to marked changes in both %MPGC and %TRPG(in0–3h) but did increase the value of T%MPGC from 20 to 50 min. Comparative study between pulmonary administered insulin (PAI and subcutaneously administered insulin (SAI) showed that the T%MPGC for PAI was about 1 5 of that for SAI with an acceptable duration for maintaining the lowering of plasma glucose. The apparent values of %MPGC and %TRPC 0–3h for PAI were about 36% of those for SAI and related to incomplete dose consumption as part of PAI was always retained inside the nebulizer. The corrected bioavailability for PAI was therefore calculated and found to be greater than 50% of that for SAI.

Wet versus dry enamel ablation by Er:YAG laser

The purpose of this study was to observe tooth structure and pulpal temperature changes in extracted human teeth subjected to a pulsed Er:YAG (2.94 μm) laser. Two teeth were irradiated while dry and three teeth while moistened by a fine water mist. When the dry teeth were irradiated, there was minimal enamel ablation. SEM of the resulting surface showed rounded fragments of enamel rods, enamel melting, cracks, and smooth-edged voids. Intrapulpal temperature measured by thermal sensor rose more than 27° C. When the laser application on the teeth was pulsed with a constant fine water mist, enamel and dentin were efficiently ablated. SEM of the resulting surfaces showed fissures and conical craters with sharp enamel projections remaining. Intrapulpal temperatures rose an average of 4° C. These results indicate that pulsed Er:YAG (2.94 μm) used with a water mist removes enamel and dentin without producing significant pulpal temperature changes.