scholarly journals Effect of Growth Parameters on Substructure Spacing in NaCl Ice Crystals

1969 ◽  
Vol 8 (52) ◽  
pp. 153-164 ◽  
Author(s):  
Gary Lofgren ◽  
W. F. Weeks
Keyword(s):  
Growth Parameters ◽  
Solute Concentration ◽  
Cold Plate ◽  
Growth Data ◽  
Thin Sections ◽  
Unidirectional Freezing ◽  
Least Squares Fit ◽  
Cellular Substructure ◽  
Image Position ◽  
Good Agreement

The effect of growth velocity υ and solute concentration C on the cellular substructure that develops in NaCl ice is studied in the range 3×10−3 to 10−5 cm s−1 and 1 to 100‰ respectively. The substructure is the result of the formation of a constitutionally super-cooled zone in the liquid ahead of the advancing interface. Unidirectional freezing runs were made by placing a cold plate in contact with the “top” of the solution and using cold-plate temperatures of −20 and −70°C. The growth velocities were determined from a least-squares fit of the growth data to a power series. The average spacings between neighboring substructures a 0 were measured from photomicrographs of precisely located thin sections. Log-log plots of a 0 against υ show that the slope n gradually changes as a function of υ. In the run where no convection occurred, n changes from to 1 as υ decreases in agreement with the prediction of Bolling and Tiller. The results of Rohatgi and Adams are also shown to be in good agreement with this prediction. On the other hand when convection occurs, n changes from to approximately o as υ decreases. This is caused by convection reducing the effective value at C at the growing interface. The variation of a 0 with C is quite complex and shows a minimum in the composition range 9 to 25‰ NaCl.

scholarly journals Effect of Growth Parameters on Substructure Spacing in NaCl Ice Crystals

1969 ◽  
Vol 8 (52) ◽  
pp. 153-164 ◽  
Author(s):  
Gary Lofgren ◽  
W. F. Weeks
Keyword(s):  
Growth Parameters ◽  
Solute Concentration ◽  
Cold Plate ◽  
Growth Data ◽  
Thin Sections ◽  
Unidirectional Freezing ◽  
Least Squares Fit ◽  
Cellular Substructure ◽  
Image Position ◽  
Good Agreement

The effect of growth velocity υ and solute concentration C on the cellular substructure that develops in NaCl ice is studied in the range 3×10−3 to 10−5 cm s−1 and 1 to 100‰ respectively. The substructure is the result of the formation of a constitutionally super-cooled zone in the liquid ahead of the advancing interface. Unidirectional freezing runs were made by placing a cold plate in contact with the “top” of the solution and using cold-plate temperatures of −20 and −70°C. The growth velocities were determined from a least-squares fit of the growth data to a power series. The average spacings between neighboring substructures a0were measured from photomicrographs of precisely located thin sections. Log-log plots of a0against υ show that the slope n gradually changes as a function of υ. In the run where no convection occurred, n changes from to 1 as υ decreases in agreement with the prediction of Bolling and Tiller. The results of Rohatgi and Adams are also shown to be in good agreement with this prediction. On the other hand when convection occurs, n changes from to approximately o as υ decreases. This is caused by convection reducing the effective value at C at the growing interface. The variation of a0with C is quite complex and shows a minimum in the composition range 9 to 25‰ NaCl.

scholarly journals On the Rates of Growth of Grains and Crystals in South Polar Firn

1969 ◽  
Vol 8 (53) ◽  
pp. 241-252 ◽  
Author(s):  
Anthony J. Gow
Keyword(s):  
Crystal Growth ◽  
Cross Sections ◽  
Mean Annual Temperature ◽  
Growth Data ◽  
Cross Sectional ◽  
Thin Sections ◽  
The Mean ◽  
Image Position ◽  
Rates Of Growth ◽  
Strong Linear Relationship

The size of firn crystals as a function of age has been investigated in thin sections to a depth of 49 m at the South Pole. Grain cross-sections increased in size from 0.24 mm2 at 0.1 m depth to 0.63 mm2 at 10 m. Crystals, as distinct from grains, increased in size from 0.18 to 0.43 mm2 over the same interval, implying that grains are generally composed of just one or two crystals rather than several as is frequently contended. The mean crystal cross-section increased linearly with the age of the firn at a rate of 0.0006 mm2 year−1; in 388 year old firn at 49 m the crystal size measured 0.63 mm2. Analysis of crystal-growth data from other locations in Antarctica and Greenland also revealed a strong linear relationship between the mean cross-sectional arcas (D2) of crystals (in mm2) and their ages in years (t), i.e. . The fact that the temperature dependence of the crystal growth rate K can be expressed very satisfactorily in an equation of the form K = K0 exp (E/RT) confirms predictions that crystal growth in firn is essentially analogous to grain growth in metallic and ceramic sinters. An extrapolation of available data indicates that crystal growth rates in dry firn could be expected to vary by two orders of magnitude (0.0003 to 0.03 mm2 year−1) over the temperature range −60° to −15°C. A method of utilizing crystal growth-mean annual temperature data to determine accumulation rates in snow is demonstrated.

scholarly journals On the Rates of Growth of Grains and Crystals in South Polar Firn

1969 ◽  
Vol 8 (53) ◽  
pp. 241-252 ◽  
Author(s):  
Anthony J. Gow
Keyword(s):  
Crystal Growth ◽  
Cross Sections ◽  
Mean Annual Temperature ◽  
Growth Data ◽  
Cross Sectional ◽  
Thin Sections ◽  
The Mean ◽  
Image Position ◽  
Rates Of Growth ◽  
Strong Linear Relationship

The size of firn crystals as a function of age has been investigated in thin sections to a depth of 49 m at the South Pole. Grain cross-sections increased in size from 0.24 mm2at 0.1 m depth to 0.63 mm2at 10 m. Crystals, as distinct from grains, increased in size from 0.18 to 0.43 mm2over the same interval, implying that grains are generally composed of just one or two crystals rather than several as is frequently contended. The mean crystal cross-section increased linearly with the age of the firn at a rate of 0.0006 mm2year−1; in 388 year old firn at 49 m the crystal size measured 0.63 mm2. Analysis of crystal-growth data from other locations in Antarctica and Greenland also revealed a strong linear relationship between the mean cross-sectional arcas (D2) of crystals (in mm2) and their ages in years (t), i.e.. The fact that the temperature dependence of the crystal growth rateKcan be expressed very satisfactorily in an equation of the formK=K0exp (E/RT) confirms predictions that crystal growth in firn is essentially analogous to grain growth in metallic and ceramic sinters. An extrapolation of available data indicates that crystal growth rates in dry firn could be expected to vary by two orders of magnitude (0.0003 to 0.03 mm2year−1) over the temperature range −60° to −15°C. A method of utilizing crystal growth-mean annual temperature data to determine accumulation rates in snow is demonstrated.

scholarly journals MAX-DOAS observations of aerosols, formaldehyde and nitrogen dioxide in the Beijing area: comparison of two profile retrieval approaches

2015 ◽  
Vol 8 (2) ◽  
pp. 941-963 ◽  
Author(s):  
T. Vlemmix ◽  
F. Hendrick ◽  
G. Pinardi ◽  
I. De Smedt ◽  
C. Fayt ◽  
...  
Keyword(s):  
Standard Deviation ◽  
A Priori ◽  
Systematic Bias ◽  
Aerosol Extinction ◽  
Data Set ◽  
Near Surface ◽  
Beijing Area ◽  
Least Squares Fit ◽  
Relative Differences ◽  
Good Agreement

Abstract. A 4-year data set of MAX-DOAS observations in the Beijing area (2008–2012) is analysed with a focus on NO2, HCHO and aerosols. Two very different retrieval methods are applied. Method A describes the tropospheric profile with 13 layers and makes use of the optimal estimation method. Method B uses 2–4 parameters to describe the tropospheric profile and an inversion based on a least-squares fit. For each constituent (NO2, HCHO and aerosols) the retrieval outcomes are compared in terms of tropospheric column densities, surface concentrations and "characteristic profile heights" (i.e. the height below which 75% of the vertically integrated tropospheric column density resides). We find best agreement between the two methods for tropospheric NO2 column densities, with a standard deviation of relative differences below 10%, a correlation of 0.99 and a linear regression with a slope of 1.03. For tropospheric HCHO column densities we find a similar slope, but also a systematic bias of almost 10% which is likely related to differences in profile height. Aerosol optical depths (AODs) retrieved with method B are 20% high compared to method A. They are more in agreement with AERONET measurements, which are on average only 5% lower, however with considerable relative differences (standard deviation ~ 25%). With respect to near-surface volume mixing ratios and aerosol extinction we find considerably larger relative differences: 10 ± 30, −23 ± 28 and −8 ± 33% for aerosols, HCHO and NO2 respectively. The frequency distributions of these near-surface concentrations show however a quite good agreement, and this indicates that near-surface concentrations derived from MAX-DOAS are certainly useful in a climatological sense. A major difference between the two methods is the dynamic range of retrieved characteristic profile heights which is larger for method B than for method A. This effect is most pronounced for HCHO, where retrieved profile shapes with method A are very close to the a priori, and moderate for NO2 and aerosol extinction which on average show quite good agreement for characteristic profile heights below 1.5 km. One of the main advantages of method A is the stability, even under suboptimal conditions (e.g. in the presence of clouds). Method B is generally more unstable and this explains probably a substantial part of the quite large relative differences between the two methods. However, despite a relatively low precision for individual profile retrievals it appears as if seasonally averaged profile heights retrieved with method B are less biased towards a priori assumptions than those retrieved with method A. This gives confidence in the result obtained with method B, namely that aerosol extinction profiles tend on average to be higher than NO2 profiles in spring and summer, whereas they seem on average to be of the same height in winter, a result which is especially relevant in relation to the validation of satellite retrievals.

Effect of Pressure on Bubble Growth Within Liquid Droplets at the Superheat Limit

1982 ◽  
Vol 104 (4) ◽  
pp. 750-757 ◽  
Author(s):  
C. T. Avedisian
Keyword(s):  
Vapor Bubble ◽  
Bubble Growth ◽  
High Speed ◽  
Ambient Pressure ◽  
Organic Liquid ◽  
Liquid Droplets ◽  
Growth Data ◽  
Two Phase ◽  
Photographic Evidence ◽  
Good Agreement

A study of high-pressure bubble growth within liquid droplets heated to their limits of superheat is reported. Droplets of an organic liquid (n-octane) were heated in an immiscible nonvolatile field liquid (glycerine) until they began to boil. High-speed cine photography was used for recording the qualitative aspects of boiling intensity and for obtaining some basic bubble growth data which have not been previously reported. The intensity of droplet boiling was found to be strongly dependent on ambient pressure. At atmospheric pressure the droplets boiled in a comparatively violent manner. At higher pressures photographic evidence revealed a two-phase droplet configuration consisting of an expanding vapor bubble beneath which was suspended a pool of the vaporizing liquid. A qualitative theory for growth of the two-phase droplet was based on assuming that heat for vaporizing the volatile liquid was transferred across a thin thermal boundary layer surrounding the vapor bubble. Measured droplet radii were found to be in relatively good agreement with predicted radii.

scholarly journals CORRECTION OF POLYRIBOSOME DISTRIBUTIONS AS OBSERVED IN CELL SECTIONS BY ELECTRON MICROSCOPY

1964 ◽  
Vol 22 (3) ◽  
pp. 613-621 ◽  
Author(s):  
William Perl
Keyword(s):  
Electron Microscopy ◽  
Probability Method ◽  
Section Thickness ◽  
Thin Sections ◽  
Comparison Of The Results ◽  
Good Agreement ◽  
Rabbit Reticulocytes

Clusters of ribosomes observed by electron microscopy in thin sections of rabbit reticulocytes are of the same order of size as the section thickness of 600 A. Many of the observed clusters must therefore have been transected by the section surfaces and observed as clusters containing fewer ribosomes. A probability method of correcting for this effect is given. Comparison of the results with grid observations of ribosome distributions indicates sufficiently good agreement for application to cell section observations.

scholarly journals Starost, rast i morfometrija otolita palamide (Sarda sarda Block, 1793) iz istočnog Sredozemnog mora

2018 ◽  
Vol 59 (1) ◽  
pp. 97-110 ◽  
Author(s):  
Mado Kotsiri ◽  
Ioannis E. Batjakas
Keyword(s):  
Growth Parameters ◽  
Eastern Mediterranean ◽  
Fork Length ◽  
Cold Season ◽  
Age And Growth ◽  
Fish Length ◽  
Thin Sections ◽  
Significant Relationships ◽  
The One ◽  
Sarda Sarda

The otoliths of the Atlantic bonito, Sarda sarda (Bloch, 1793), were examined with the aim to estimate the age and growth of the species in the eastern Mediterranean Sea and to reveal possible relationships between otolith shape or size and age. All specimens used in this study, ranging from 7.2 to 70.4 cm in fork length and from 20 to 4889 g in total weight, were caught in the Aegean and Ionian Seas during the period 1997-2010. Otolith morphometry was studied using image analysis techniques for all intact sagittae ranging in weight from 0.6 to 11.3 mg and four shape indices were calculated. No statistical significant differences between left and right otolith morphometric variables were found. The age of fish was estimated by counting the pairs of opaque and translucent bands in transversal thin sections of otoliths. The estimated ages ranged from 0+ to 7 years and the von Bertalanffy growth parameters were determined \((L∞=79.9 cm, k=0.261 and to=-1.230 years)\). The examination of the type of growth bands at the outside margin of each otolith per month showed that one translucent band is formed annually during the cold season. The results revealed statistically significant relationships between otolith morphometric variables and fish length or age. Among the variables, otolith weight was the one that showed the highest correlation with age (R=0.77). Therefore, otolith weight could represent a valuable criterion for age estimation in Atlantic bonito that is objective, economic and easy to perform compared to annuli counting method in hard parts.

scholarly journals Pubertal growth in normal Thai children: a longitudinal study

2010 ◽  
Vol 4 (5) ◽  
pp. 793-795
Author(s):  
Suttipong Wacharasindhu ◽  
Vichit Supornsilchai ◽  
Suphab Aroonparkmongkol ◽  
Thaninee Sahakitrungrueng
Keyword(s):  
Longitudinal Study ◽  
Growth Parameters ◽  
Longitudinal Growth ◽  
Compensatory Mechanism ◽  
Growth Data ◽  
Clinical Practices ◽  
Normal Children ◽  
Pubertal Onset ◽  
Pubertal Growth ◽  
Height Gain

Abstract Background: Pubertal growth data in Thai children has been reported as cross-sectional studies. There is no longitudinal study in Thai children. Objective: Investigate the longitudinal growth data in normal Thai children including the relationship between age at pubertal onset and other growth parameters. Material and method: Eighty-eight normal children (44 boys, 44 girls) were longitudinally assessed for the growth and puberty until they reached their final adult height. Pubertal staging was assessed by the Tanner method. Results: Mean age of pubertal onset was 10.2 ± 1.2 years for girls and 12.2 ± 1.0 years for boys. Total pubertal height gain was 18.3 ± 4.0 cm for girls and 22.3 ± 4.4 cm for boys. Total pubertal height gain had a negative correlation with age at pubertal onset for girls, but not for boys. Conclusion: The onset of puberty was not much changed from previous studies. Girls with early puberty had a higher pubertal height gain. This might be due to a compensatory mechanism. These longitudinal growth data can be used as a reference in clinical practices for Thai children.

Age and growth of blue grenadier, Macruronus novaezelandiae (Hector), in south-eastern Australian waters

1987 ◽  
Vol 38 (5) ◽  
pp. 625 ◽  
Author(s):  
TJ Kenchington ◽  
O Augustine
Keyword(s):  
Growth Parameters ◽  
Growth Curves ◽  
Growth Patterns ◽  
Age And Growth ◽  
Double Blind ◽  
Blind Test ◽  
Thin Sections ◽  
South Eastern ◽  
Weight Data ◽  
Immature Fish

Blue grenadier, Macruronus novaezelandiae, from south-eastern Australian waters were aged, using their otoliths (whole and in transverse thin sections). The greatest recorded age was 25 years. A double blind test showed that the recorded ages were sufficiently reproducible to use in fitting growth curves (Index of Average Percent Error: 8%), but not sufficiently so to assign individuals to particular year-classes. Von Bertalanffy growth curves were fitted to both length and weight data. For males, Lt = 90.7 (1 - exp[-0.256(t + 1.21)]} and Wt = 2.62 (1 - exp[-0.277(t + 1.39)]}3. For females, Lt = 99.3 {l - exp[-0.203(t + 1.48)]} and Wt = 4.16{1 - exp[-0.157(t + 2.93)]}3. L is the length in centimetres, W is the weight in kilograms and t is the age in years. A comparison with length-frequency modes validated the growth curves for immature fish, but no validation was possible for the adults. The $exes have qignificantly different growth patterns. Their growth parameters are typical of those of commercially exploited, temperate gadoid fishes and show no modification for the deep-water zone inhabited by blue grenadier.

scholarly journals Hybrid Poplar Genotype Affects Attack Incidence by the Poplar-and-Willow Borer (Cryptorhynchus lapathi)

2003 ◽  
Vol 18 (4) ◽  
pp. 276-280 ◽  
Author(s):  
J.D. Johnson ◽  
K.R. Johnson
Keyword(s):  
Pacific Northwest ◽  
Arid Regions ◽  
Growth Parameters ◽  
Wood Quality ◽  
Hybrid Poplar ◽  
Stem Volume ◽  
Growth Data ◽  
Cascade Mountains ◽  
Poplar Plantations ◽  
Lombardy Poplar

Abstract Increasing incidence of the poplar-and-willow borer (Cryptorhynchus lapathi) in Pacific Northwest hybrid poplar plantations has resulted in reduced wood quality and stem breakage. Three replicated, 5-yr-old clone trials established in the vicinity of Pullman, WA were rated for host attack preference. Attacks by C. lapathi were found to be significant for plantation, clone, and the clone by plantation interaction. Attack rating among clones was affected by genotype. Those clones possessing P. nigra parentage, including Lombardy poplar, OP-367, and PC-6, showed significantly lower attacks across all plantations. Within the P. trichocarpa × P. deltoides (TD) hybrids, both 58-280 and 50-194 consistently exhibited lower attacks compared to the remaining four TD hybrids. Plantation, clone, and the plantation by clone interaction affected tree growth parameters significantly. Mean clone stem volume across sites from largest to smallest was: 49-177, OP-367, 50-197, 52-225, PC-6, 50-194, 58-280, 15-29, and Lombardy poplar. Attempts to correlate attack rating with any parameter of tree size were unsuccessful. Combining growth data and attack rating, OP-367 would be recommended for planting in arid regions east of the Cascade Mountains, followed by PC-6, 50-194 and 58-280. Future hybrid poplar breeding for this region should consider P. nigra as a parent. West. J. Appl. For. 18(4):276–280.

Sign in / Sign up

Export Citation Format

Share Document