Greatest Mass Research Articles

Comparison of atomization and ionization processes in direct current, radiofrequency and microsecond pulse discharges

Glow discharge spectrometry has attracted growing interest in using faster pulsed power supplies as a diagnostic tool. In this study, a comparison of dc, rf and microsecond pulse (µs-pulse) GDs was made to determine the relative efficiency of the discharge power. The sputtering rates of the different power modes as evidenced by direct mass loss measurements showed the greatest mass loss for the µs-pulse. Emission spectra of the three sources were also analysed. The emission signal intensity for Cu from the µs-pulse was two orders of magnitude greater than those from the others. It was also noted that the ratios of the atom versus ion emission intensities differed among the three modes. Optical temperature measurements of N2+ rotational and Fe1 excitation emission spectra were investigated. The N2+ rotational temperatures varied between 400 K for the µs-pulse discharge up to 650 K for the dc power source, whereas a constant Fe1 excitation temperature of 3600–3900 K for all modes was measured.

Ontogenetic development of gut function, growth, and metabolism in a wild bird, the Red Jungle Fowl

We measured the ontogeny of growth rate, food intake, metabolic rates, organ masses, and intestinal nutrient transporter and hydrolase activities in a wild bird for comparison with previous measurements of the same quantities in four domesticated or laboratory animals. Analysis of covariance with body mass as a covariate showed that body mass accounted for most of the age-related variation in all variables, but that age itself still had a significant effect on most variables. Among organs studied, the ceca exhibited the greatest mass increase with age. Energy intake and resting and basal metabolic rates increased with age, but digestive efficiency, cost of growth, and sustained metabolic scope were independent of age. Although intestinal brush-border glucose and proline uptakes and sucrase activity declined with age, the corresponding capacities increased with age because of compensating increases in intestinal mass. Intestinal passive permeability to glucose was undetectably low. Unlike the four domesticated animals studied to date, jungle fowl possess no intestinal reserve capacities (excesses of capacity over dietary nutrient intake). Cecal absorption may contribute significantly to glucose uptake capacity with increasing age.

Chemical vapour deposition of TiN layers in various glow discharge regions

After the treatment the samples were golden in colour, which is characteristic of titanium nitride. The presence of TiN was confirmed by X-ray examination. Table I gives the results, referred to unit surface area, of gravimetric examinations of the samples after the treatment. The greatest mass increases were observed in samples placed on the cathode, and the smallest in those placed on the anode. The differences between the increases in the mass of the samples placed on the cathode and those placed in the plasma region and on the anode were much greater than those observed when comparing the samples placed on the anode and in the plasma region. Some small differences also occurred between samples with different substrates but no unequivocal relation could be found here. Figs 2 and 3 show the appearance of the surface of the TiN layers deposited on SW7M steel and on A1203 placed in different regions of the glow discharge. As seen from the figures, the difference in the surface topography and in the size of the growing grains depend on where the TiN synthesis has occurred. The surfaces of the samples which were at the cathode potential are covered uniformly with grains of various size. The samples placed at the anode and plasma potentials are covered with much smaller grains, concentrated in greater agglomerations against the background of fine-crystalline structure.

Particle size distribution and chemistry of late winter Arctic aerosols

Mass size distributions of element concentrations in Arctic aerosols at Barrow, Alaska, were measured from March 16 to May 6, 1986, and their correlations were examined statistically by absolute principal component analysis. In eight particle size fractions from <0.25 to >16 μm aerodynamic diameter (μmad), from eight‐stage cascade impactor sampling and proton‐induced X‐ray emission (PIXE) analysis, four types of aerosol components were resolved. One, resembling sea salt in composition, shows a maximum mass at 2–4 μmad and not detected at <0.25 μmad. Sulfur is enriched in fine particles 0.25–1 μmad but not in coarse; chlorine is depleted in 0.5–1 μmad particles, conforms to sea salt composition >8 μmad, but is about 50% enriched in other fine and coarse fractions, suggesting gas‐particle chemical interactions during aerosol aging. The sea salt aerosols appear only in a few elevated concentration periods, with transport likely from open ocean areas. Dust components are found in all size fractions, with a maximum concentration at 1–2 μmad and a rough symmetry about the maximum when sulfur is not included, suggesting eolian dust particles. Their compositions resemble average crust materials. On these dust particles, sulfur contents show a linear relationship with surface areas, suggesting uptake of gaseous sulfur compounds. Carbonaceous fuel combustion pollutants are indicated by the presence of Si, Cl, and several trace metals and the absence of Al. They are present in all size fractions, usually rich in sulfur with the highest concentration in ultrafine particles <0.25 μmad, strongly suggesting a gas phase origin and consistent with condensation of chloride salt and SiO vapors formed during coal or other fuel combustion. Bromine‐sulfur components are in every size fraction and contain most of the measured bromine, greatly in excess of sea salt Br. The greatest mass is at <0.25 μmad, suggesting a gas phase origin that may involve both nucleation and surface adsorption.

Seasonal Changes in Body Shape and Mass in the Salamander, Hynobius nigrescens

Male and female Hynobius nigrescens show pronounced changes in body shape associated with aquatic reproduction. Soon after entering the breeding pond there is a large increase in body mass, head width, and tail height in males, caused by changes in connective tissue under the skin and by storage of seminal fluid in the vasa deferentia. These features decline gradually in postbreeding males prior to leaving the pond. Females show little seasonal variation in head width or tail height, but exhibit a large increase in body mass after ovulation. This is the result of absorption of water during the formation of egg sacs. Mazzi and Vellano (1987) stated that some salamanders were characterized by an increase in body mass and tail height during the aquatic phase. This phenomenon is well known in sal- amandrids. For example, in Taricha granulosa breeding males have the greatest body mass and tail height (Specker and Moore, 1980). In Tri- turus spp. the male develops a tall, crenulated crest and pronounced tail fin during the breed- ing season (Halliday, 1977). In Notophthalmus

Radtal velocities of nearby K and M dwarfs

A correlation radial-velocity meter was used during 1985-87 to make 931 measurements of the radial velocities of 206 nearby stars in Gliese's catalog. The characteristic accuracy was 0.5 km/sec. A homogeneous sample of 162 K and M dwarfs in the region delta > -10/degree/, 14/sup h/ < ..cap alpha.. < 3/sup h/ contains 41 stars with variable or probably variable velocity; 10 stars have been identified for the first time as spectroscopic binaries. The fraction of spectroscopic binaries in the classes K0-K2 is 17%, in the classes M0 and later 36%, and in the complete sample 27%. Among the systems with a period less than one year low-mass (M/sub 2/ sin i < 0.1Msub solar) satellites have not been found; for all stars the velocity spread exceeds 7 km/sec. For the systems GL 58.2 and 791.3, which have the greatest mass function, the lines of secondary components have been detected.

Mass loss and qualitative change in stream-incubated fine particulate organic matter derived from leaves differing in rate of processing

The initial quantitative breakdown of fine particulate organic matter (FPOM) was investigated by measuring the loss (over 73 days) of substrate mass of particles of known size ranges (53–125 µm, 125–250 µm, 250–500 µm, 500 µm-1 mm) and derived from known organic sources (Alnus rubra, Acer macrophyllum, Polystichum munitum). Qualitative examinations (organic content, C : N ratio) also were made. Particles ranging from 500 µm to 1 mm in diameter differed greatly from particles in other size ranges, and results of studies with these particles closely resembled results of coarse particulate (CPOM) leaf pack studies. Despite variation, alder particles generally exhibited the greatest mass loss, those of sword-fern, the least, and mass loss of bigleaf maple particles was intermediate. Organic contents of all particle substrates decreased over time. In general, the C : N ratios of alder particles increased, those of bigleaf maple decreased, and those of sword-fern exhibited little change. All particle substrates were incubated in the field in vials, which allowed for influx of natural detritus of unknown source and period of residence. Given the overall abundance and prevalence of the FPOM resource in lotic systems, standardization of a procedure such as that used in this investigation would be useful in extending understanding of stream system processes, including detrital processing and decomposition.

The effects of intratracheally administered coarse mode particles on respiratory tract infection in mice

Because coarse mode particles are rarely studied in their existing size ranges (greatest mass about 5–7 μn, aerodynamic diameter), we investigated the effects of four such particles, quartz, ferric oxide, calcium carbonate, and sodium feldspar, on host defenses against bacterial pulmonary infection. Mice which received intratracheal instillations of 10, 33, and 100 μg mouse were exposed within an hour to aerosols of viable Streptococcus, and pneumonia-induced mortality was measured. At 33 and 100 μg mouse, all particles significantly increased mortality. At the lower dose, only Fe 2O 3 caused a significant increase in mortality. To evaluate potential delayed effects, mice were challenged with the bacteria 24 h after exposure to 100 μg particles/mouse. Delaying the challenge did not significantly alter the response, except for the sodium feldspar group for which a partial recovery was observed. When mice exposed to 100 μg particles/mouse received aerosols of Klebsiella pneumoniae 24 h later, there was no significant effect on pulmonary bactericidal activity. For the model system used, it appears that Fe 2O 3, CaCO 3, and sodium feldspar have effects roughly equivalent to quartz.

The Cuban Exiles: An Analytical Sketch

Without question, Cuba's most successful ‘export’ from the very beginning of the Castro period has not been revolution, but the physical removal of its domestic enemies. For whatever reason individual Cubans came to reject the new order, the decision to part physically from their homeland was made by enough people to develop into what is probably the greatest mass migration in the history of the Western Hemisphere. Latest estimates provided by the Department of State indicate that approximately 560,000 persons have left Cuba since 1959 to settle in other countries—all but 50,000 in the continental United States or Puerto Rico

The cross striation pattern of the fibrin fibril.

Two different cross striation patterns can be seen under the electron microscope when fibrin fibrils are treated with heavy metal salts. The first shows two bands of different intensities per period (Type I), while the second has four bands per period (Type II). In this work, the factors involved in the formation of this particular cross striation pattern have been investigated. The origin of the Type I pattern is attributed to a reaction between uranyl acetate or phosphotungstic acid with the polar groups of fibrin (positive staining). Type II pattern arises from the embedding of excess heavy metal salts in the loosely structured portions of the fibrin fibril (negative staining). The sites of accumulation of the polar groups are not the areas of greatest mass density of the molecule.

Voluntary consumption of forage by sheep and its relation to the size and shape of particles in the digestive tract

Two alfalfa varieties and four grass species were harvested for hay at several stages of maturity. Each hay was given to sheep to provide measures of voluntary consumption and digestibility. Digesta samples were obtained from the reticulo-rumen, omasum and abomasum by killing the sheep at the end of the feeding periods.Sieving analyses of the digesta revealed that the fraction retained by a 0·25-mm sieve provided greater differentiation between experimental treatments than those retained by 0·5-, 1·0- or 2·0-mm sieves. The weight percentage of this fraction was used as a measure of the relative particle size despite its profound dependence on size, shape, density and distribution of individual particles.The variation in relative particle size of digesta from different sheep fed on the same diet was illustrated by coefficients of variation ranging from 4 to 11%. Four replicates, however, were sufficient to detect numerous differences (P&lt;0·05) between experimental treatments.Omasal digesta from alfalfa hay had a greater relative particle size than those from the grass hays at comparablematuritystages. This may be attributable to an apparently more compact particle shape observed in the alfalfa digesta, assuming that in a simple physical sieving process the most compact particle passing a given opening will have the greatest mass. It was proposed that digesta particle shape may have greater specific importance than relative particle size for the rate of passage and voluntary intake of coarse roughage.A direct relationship was observed between voluntary feed consumption and the relative particle size of omasal digesta from different grass hays at similar maturity stages. This was the reverse of that observed between different maturity stages within hay species. It was hypothesized that the former relationship was due mainly to changing mass of the individual particles passing the reticulo-omasal opening, whereas the latter relationship was caused mainly by the particle size distribution.The relationship between the relative particle size of digesta from the reticulo-rumen and that of digesta from the omasum supports the theory that the reticulo-omasal opening is the site of major obstruction for the passage of coarse roughage through the digestive system of ruminants.