Active deposit

Barite is abundant in the massive strata-bound ore bodies (black and barite ores) in Kuroko deposits and occurs in the ferruginous chert ore in Kuroko deposits, and chimneys in active deposits at back-arc basins. 

In order to develop more informative and direct method of studying the spillover effect of active particles, the authors of [37] suggested to use the sensor method of detecting migrating particles based on separation of sensor and emitter (donor) of active particles. The latter consists of small metal globules, or clusters (with a diameter of about 20-30 A) of Pt, Pd, Ni, etc. (activator) deposited on quartz or sapphire (AI2O3) plate in the form of a strip less than 1 cm wide. The sensor for detection of hydrogen atoms consisted of a zinc oxide strip (with a width of about 0.1 cm and thickness wlOO nm) deposited on the same plate at a distance of 0.03 or 0.6 cm (two versions) from the inner boundaries of activator strips [38]. 

Volcano-sedimentary ore deposits are syngenetic deposits precipitated from sea water enriched in metals by submarine volcanic activity. Deposits of this type are also called submarine exhalative-sedimentary deposits. Stratabound lead-zinc-copper deposits associated with marine sedimentary volcanic sequences belong to this category. Important examples are Kuroko deposit in Japan, Mt. Isa in Australia, Sullivan deposit in British Columbia, Canada, Rammelsberg in Germany and Rampura-Agucha in Rajasthan, India. 

A source of Aphrodisin which is present in an alternate emission vehicle is that of female saliva. Self-grooming spreads the signal on flank fur and passive or active deposition may then leave traces during contact with burrow walls. The sebaceous flank glands being inconspicuous (and dimorphic) in the female do not play a significant role in advertising her presence. 

The sources of a-rays which produce the tracks on the bare CR-39 detectors are divided into airborne activity and activity deposited on the surface of the detectors. The relationship between time-averaged radon concentration (Cq) and the track density (T) on the bare track detector is represented by... 

Briggs, G.H., Distribution of the Active Deposits of Radium, Thorium and Actinium in Electric Fields, Phil. Mag. 41, 357, 1921. 

Wellisch, E.M. The Distribution of Active Deposit of Radium in an Electric Field, Philosophical Magazine 26 623-635 (1913). 

After exposure, the outside surface of the cast was cleansed until the activity of the washes was less than 10X the background of a gamma well scintillation counter. The cast was cut into separate bifurcations and airway sections and each section was counted to determine the amount of aerosol deposited. Sane samples contained both airway and bifurcation sections because of the complex configuration of the cast. For combination samples, the total activity deposited was equally apportioned between each of the airways and bifurcations. End airways were included for determination or total deposition but not in any of the analyses because flow disturbances at open ends may have affected deposition. The surface area of each sample was measured separately. The surface density for each cast segment was calculated by dividing the activity measured in the sample by the interior surface area of that sample. 

In 1904 Miss Harriet Brooks of McGill University in Montreal studied the active deposit of short life which forms as a thin layer on all substances which have been exposed to radon (43), a phenomenon which Soddy compared to a sort of continuous snowstorm silently going on covering every available surface with this invisible, unweighable, but intensely radioactive deposit (83). From Miss Brooks s researches and... 

Marsden, E. and T. Barratt, The o-particles emitted by the active deposits... 

However, an enzyme that uses GDP-D-glucose as a substrate in order to synthesize a cellulose-like product has been reported to be present in developing cotton fibers during the period when primary-wall cellulose synthesis normally occurs, but is absent from older fibers undergoing active deposition of secondary-wall cellulose.303... 

Scaling occurs if a dissolved salt exceeds its saturation point. Most cooling systems can tolerate a slight degree of supersaturation of (for example) calcium carbonate for short periods however, the degree of scaling and rate of deposition are dependent on a number of critical factors. The primary factors are degree of supersaturation, residence time, temperature, active deposition sites, pH, and the DCA product employed. 

Chamberlain Dyson (1956) measured deposition of unattached 212Pb in a rubber model of the trachea and main bronchi. At an inspiratory flow of 20 1 min-1, corresponding to a ventilation rate of about 0.6 m3 h-1, the activity deposited per cm2 of surface in the bronchi was 0.18% of that entering the trachea. No difference was found in the deposition of unattached 218Po (RaA) compared with unattached 212Pb (ThB). 

If dry deposition, or occult precipitation were a dominant mode of deposition, the activity deposited would be expected to depend on the type of vegetation cover. Graustein Turekian (1987) deduced identical values of vg from measurements of 137Cs in soil cores and Sr in bucket collections (Table 2.13), which indicated little effect of vegetation. At forested sites in the Appalachian Mountains, however,... 

Table 2.15. Interception by foliage of particulate activity deposited in rain (analysis of results of Hoffman et al., 1989)...

Transfer coefficients can also be deduced from statistics of the levels of 90Sr and 137Cs in milk measured during monitoring of the fallout from nuclear weapon tests. This has the advantage over experimental work of taking into account variations in agricultural practices, but introduces complications such as the use of root crops and imported feed for cattle and the uptake by crops from the soil of activity deposited in previous years. UNSCEAR (1977) analysed data from a number of countries, obtained in the years 1958-74, in the form,... 

Volunteers smoked the labelled cigarettes. The activity deposited in the mouth, and the activity removed to the GI tract in the 15-min interval between smoking and measurement, were measured with collimated detectors. The clearance of activity from the lung was followed for 2 d to allow the deposit to be fractionated into TB and P components. Comparative tests were also done with subjects inhaling 2.5-jum polystyrene particles, which were also labelled with 123I. 

Plasma-Activated Deposition fur Optical Preform Preparation. . . . 113... 

Plasma-Activated Deposition for Optical Preform Preparation... 

High quality optical fibers obtained using the PCVD method demonstrate that the plasma activated deposition fulfills the extreme requirements for optical fibers almost ideally. This is underlined by the optical properties of a large number of fibers prepared under the same PCVD conditions on a pilot plant scale which show a narrow distribution in their attenuation and pulse broadening values. This in turn is directly correlated with the good process control which is achievable. 

Low-temperature plasma processes, such as gas plasma treatment and plasma polymerization, have unique advantages in that active (depositing) species strongly interact with the surface of the substrate and modify the surface state. An ultrathin layer of plasma polymer, e.g., thickness less than 50 nm, can be viewed as a new surface state because such a thin layer does not develop a characteristic bulk... 

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