Size-energy relationship exponents in comminution

Mitochondria are vital cellular organelles that have the ability to change their shape under different conditions, such as in response to stress, disease, changes in metabolic rate, energy requirements and apoptosis. In the present study, we observed remodelling of mitochondria during spermiogenesis and its relationship with mitochondria-associated granules (MAG). At the beginning of spermiogenesis, mitochondria are characterised by their round shape. As spermiogenesis progresses, the round-shaped mitochondria change into elongated and then swollen mitochondria, subsequently forming a crescent-like shape and finally developing into onion-like shaped mitochondria. We also noted changes in mitochondrial size, location and patterns of cristae at different stages of spermiogenesis. Significant differences (P<0.0001) were found in the size of the different-shaped mitochondria. In early spermatids transitioning to the granular nucleus stage, the size of the mitochondria decreased, but increased subsequently during spermiogenesis. Changes in size and morphological variations were achieved through marked mitochondrial fusion. We also observed a non-membranous structure (MAG) closely associated with mitochondria that may stimulate or control fusion during mitochondrial remodelling. The end product of this sophisticated remodelling process in turtle spermatozoa is an onion-like mitochondrion. The acquisition of this kind of mitochondrial configuration is one strategy for long-term sperm storage in turtles.

An explicit analysis of bubble-size equilibration by volume diffusion has been derived and incorporated into the FRAS2 code. This code was developed for mechanistic analysis of transient fission-gas behavior in LMFBR fuel, but had been limited by the approximation that the time required for bubble-size adjustment, following coalescence or changes in temperature or pressure, was negligible. The equilibration phenomenon is illustrated by several idealized examples. If the fuel temperature rises linearly with time, an isolated bubble will expand rapidly toward its equilibrium size only after the temperature reaches a critical value that depends on both bubble size and heating rate. Conversely, if the temperature is reduced uniformly, an isolated bubble will shrink only until diffusion becomes too slow for further size change. The final size that is ''frozen in'' may be significantly larger than the final equilibrium size. Finally, isothermal equilibration following coalescence of two equal bubbles can be described conveniently in terms of relaxation times, which depend on bubble size and temperature. However, a complete picture of the role of equilibration in transient fission-gas behavior can only be gained through an investigation of the bubble-size distribution and its evolution. Such an investigation is carried out with the FRAS2 code, in which the explicit equilibration model is implemented. Since nonequilibrium bubbles in a thermal transient are generally overpressured, the gas represents a source of energy that can conceivably disrupt the fuel. This ''dispersive potential'' is also calculated in the FRAS2 code.

Variation in clear cornea incision size after phacoemulsification and foldable lens implantation

The authors report the cases of 37 patients encountered during the past 4 years who exhibited acute extradural hematoma but were initially treated conservatively because no or only small hematomas were observed on admission. The frequency of hematoma enlargement, hematoma size, and changes in the level of consciousness and intracranial pressure (ICP) were examined in these patients. The hematomas enlarged in 24 (64.9%) of the 37 patients, and attained a maximum thickness of 25 mm or greater in 19 patients (51.3%). The level of consciousness could be closely observed during enlargement of the hematomas in 13 patients: the level remained unchanged in eight, deteriorated in two, and improved in three, indicating relative stability in the state of consciousness despite the marked changes in hematoma size. The patients whose hematoma enlarged after the initial examination included three who underwent initial CT examination 5 hours after the injury. In five patients enlargement of extradural hematomas was observed unexpectedly during conservative treatment under ICP monitoring. The ICP also remained stable in three patients until the follow-up examination, but showed a rapid increase in two after a period of stability. However, there was no difference in the final size of the hematomas between the patients showing an increase in ICP and those who did not. These findings suggest that extradural hematomas enlarge progressively at rates varying with the condition of the source of hemorrhage. Moreover, a period of stability in the level of consciousness, such as the lucid interval seen in patients with extradural hematoma, is considered to be a period during which compensatory mechanisms can maintain the stability of the intracranial condition during progressive enlargement of the hematoma.

Computational fluid dynamics simulations incorporating supersonic turbulent gas flow models and a droplet breakup model are performed to study supersonic gas atomization for producing micron-sized metal powder particles. Generally such atomization occurs in two stages: a primary breakup and a secondary breakup. Since the final droplet size is primarily determined by the secondary breakup, parent droplets of certain sizes (1 to 5 mm) typically resulting from the primary breakup are released at the corner of the nozzle and undergo the secondary breakup. A comparison of flow patterns with and without the introduction of a liquid melt clearly indicates that the mass loading effect is quite significant as a result of the gas–droplet interactions. The flow pattern change reasonably explains why the final droplets have a bimodal mass size distribution. The transient size changes of the droplets are well described by the behavior of the Weber number. The present results based on the 1 mm parent droplets best fit previous experimental results. Moreover, the effects of inlet gas pressure and temperature are investigated in an attempt to further reduce droplet size.

&lt;p&gt;Individual tumor size predictions in the final tumor size model (lines) and observed tumor sizes (dots) for 9 example patients (indicated by the shape of the dots), 3 in each subpopulation.&lt;/p&gt;

THE CONTROL OF GRAIN SIZE IN THE MANUFACTURE OF SINTERED HARD-METAL

Nanoparticle synthesis is part of an emerging field in nanotechnology. Applications take advantage of the high surface area and confinement effects, which leads to nanostructures with different properties other than those of conventional materials. The main focus of this work was on nanoparticle synthesis based on microemulsions. Change in nanoparticle size due to changes in salt concentration and type of microemulsion was explored. TiO2 particles were prepared by a precipitation technique in which TiCl4 was solubilized in the microemulsion system of n-heptane/water/NaCl/AOT reacts with NH4OH at a controlled temperature (30℃). The micellar size and amount of water in the microemulsion phase were analyzed using dynamic light scattering and coulometer. TiO2 particles were characterized using XRD, SEM, TEM, and BET surface area analyzer. Micellar size of o/w and bicontinuous microemulsions increased with increasing NaCl concentration. However, the micelle size of w/o microemulsion decreased with increasing NaCl concentration. Higher NaCl concentration resulted in a lower amount of water in w/o microemulsions. TiO2 particle synthesized from the three different types of microemulsion showed differences in the final size and surface area, which was related to the amount of water present. TEM showed that the particle sizes synthesized from w/o microemulsion were monodispersed and smaller in size than those prepared from other types of microemulsion; they also had higher surface area.

Regulation of Growth by Ploidy in Caenorhabditis elegans

A potential-based approach for shape matching and recognition

The results are reported for an analysis of longitudinal sequences of lateral head X-rays of 50 Montreal girls, taken annually between the ages of 6 and 15 years. Mean size changes for distances within the cranial base, the maxilla and the mandible, as well as those outlining the facial polygon, are displayed on a common proportional scale based on mean sizes at 15 years old. Mean growth velocities are displayed on both a chronological age scale and on one relative to the individual age of peak growth velocity in stature. A distinct facial pattern of growth is established, In terms of the proportion of final size achieved during childhood, it is below the cranial pattern, but above the general skeletal one. This facial pattern shows a pubertal peak in growth, but one quantitatively less important than that for stature. The timing of the two peaks is closely aligned, although the evidence favours a slightly later development for the face. The mandibular ramus provided the sole exception to this common facial pattern, though some questions on maxillary growth remain open.

Emulsification mechanism and storage instabilities of hydrocarbon-in-water sub-micron emulsions stabilised with Tweens (20 and 80), Brij 96v and sucrose monoesters

SUMMARY. 1. Spatial and temporal changes in larval densities were used to infer patterns of habitat use and survivorship in a fourteen‐species assemblage of dragonflies (Odonata: Anisoptera) in a small fishless pond. The density of all species combined peaked at &gt;1000 m−2 in late summer, Most species (e.g. Libellula spp.) were restricted to shallow, nearshore habitats (&lt;1.0m in depth), but a few (e.g. Epitheca spp.) also used deeper areas of the pond. Only Perithemis tenera was most abundant in deep habitats.2. Because many species exhibited temporal shifts in their use of habitats, it was necessary to estimate survival from changes in population size, calculated as the product of density and habitat area, summed across habitats. In most species, periods of high mortality in autumn and spring were separated by 3–4 months of negligible mortality in winter. Survivorship was linear only in the two species that completed all of larval development in summer (Sympetrum vicinum and Pantala flavescens). Average survival rates for these two species (−0.0049 and −0.0079 log density d−1) were similar to those in previous studies (Lawton, 1970; Benke &amp; Benke, 1975).3. Survivorship in many species was confounded by other life history phenomena such as (i) mixed voltinism, (ii) overlapping migrant and resident cohorts, and (iii) asynchronous development within species. Asynchrony made it difficult to estimate initial and final population sizes, hence total larval survivorship. However, based on emergence data, only 0.4–3% of larvae survived after peak abundance. None of this mortality can be ascribed to vertebrate predation, and only a little to overwintering stress and starvation. Thus, predation by invertebrates might play a major role in the regulation of these populations.

We studied the mechanisms that regulate colony dynamics in a Spanish population of Lesser Kestrels, using eight years of data from banded individuals in 494 colony-years. Colony growth was positively related to breeding success at the colony the year before. However, individuals of all dispersal statuses, i.e., adult and first-breeding philopatric and immigrant birds, significantly contributed to changes in colony size, indi- cating an important effect of dispersal on colony dynamics via colony quality. Given that there is strong evidence that Lesser Kestrels base their settlement decisions on conspecifics, we tested whether immigrants used the number of previously settled residents in year t (social or conspecific attraction hypothesis) and/or the breeding performance of conspecifics in year t 2 1 (performance-based attraction hypothesis) to select their breeding colony. Breeding success of colonies varied both in space and time and was autocorrelated from one year to the next. Moreover, lifetime reproductive success of Lesser Kestrels was pos- itively associated with colony size, and individuals can predict final colony size early in the breeding season, so assumptions of both hypotheses were fulfilled. Our results support the social attraction hypothesis, since immigration was positively related to the number of philopatric adults, but not to conspecific breeding success the year before. Given that departure decisions of adults were based on personal information about breeding success and colony size is related to fitness prospects, previously settled individuals provide easy and reliable information about colony quality, and social attraction could be seen as a particular case of public information in Lesser Kestrels. Consistently, absolute numbers of both philopatric adults and immigrants increased with colony size the year before, although immigrants increased only up to a threshold beyond which this trend disappeared. Therefore, immigrants seem to be prevented from settling in the largest colonies, which could explain why all individuals do not concentrate in a few big colonies, but some settle in suboptimal colonies or colonize unoccupied sites. This opposing effect of conspecifics, together with the low levels of temporal autocorrelation in colony quality between time lags $2 yr, could promote colony size variability and facultative coloniality in this species.

The effect of calcium on activated sludge flocculation dynamics is investigated using a unique experimental technique. The technique allows on-line analysis of the size of activated sludge flocs during flocculation and provides valuable insight into the mechanisms of flocculation. Activated sludge samples were firstly sonicated for 3 minutes at 50 W and then stirred at 100 rpm. The floc size was subsequently measured on-line using a Malvern Mastersizer/E. For concentrations of calcium less than 4 meq/L no significant increase in final floc size was observed even though an increase in the initial rate of change of floc size could be seen. Addition of calcium greater than 4 meq/L resulted in a dramatic increase in floc size. Results from this investigation support the theory that cations are involved in flocculation through cationic bridging, and will be used in ongoing investigations to model the flocculation process.