Large Number Of Small Fragments Research Articles

Analysis of cultivation of remaining forest fragments in the Moju River Basin, Legal Amazon, Pará

It is known that Brazilian Amazon has been the target of changes in land use and cover caused by oil palm crop. Among other economically attractive species, they cause several impacts on the environment. One way to characterize environmental changes that have an influence on biodiversity conservation is the analysis of landscape metrics. The objective of this work was to characterize and to analyze, through landscape metrics, the remaining forest fragments in a landscape with palm oil cultivation, in the Moju River Hydrographic Basin under the perspective of the conservation of local biodiversity, making a comparative between the years of 2005 and 2017. The landscape analyzed is very fragmented, characterized by the presence of a large number of small fragments, demonstrating the strong impact of human activity in the area. The environmental compromise of the Moju River basin’s landscape with respect to ecological integrity has become notorious, since over 50% of its dense vegetation area with up to 50 ha is composed of edge environment, a factor that significantly affects the quality of the existing ecosystems. Considering the context of the Moju River basin, strategic planning measures related to the control and management of the Moju River are necessary to contribute to the process of recovery and conservation of the remaining fragments.

Field Electron Emission from the Tip of a Graphite Fiber

Usually carbon wires cannot be used for obtaining remarkable field electron emission because the difficulty of sharpening its tip with a sufficient small radius of curvature to fit the electrical field. However, a large number of small fragments are formed on tips of graphite fibers after a discharge treatment with 10 kV DC high voltage on graphite fibers. These fragments observed by SEM and HRFEM are spheres, flakes and needle-like nanostructures with the size around 50 nm. In this case, each of these spheres and flakes can be an emission center in field emissions and some detectable emission currents can be obtained with a low applied voltage. Experimental results show that a single graphite fiber of 20µm diameter can generate near 0.2 mA emission current with 4 kV applied voltage and the stability have been measured to be less than 10 %. It is expected that graphite fibers as a novel cold cathode material will provide a wide range of applications such as in flat panel displays, high-power and high-brightness vacuum electronic devices, and vacuum microelectronic devices.

Microstructure characterization of SiC nanowires as reinforcements in composites

SiC nanowires have been rarely investigated or explored along their axial direction by transmission electron microscopy (TEM). Here we report the investigation of the cross-section microstructure of SiC nanowires by embedding them into Al matrix. Morphology of SiC nanowires was cylindrical with smooth surface or bamboo shape. Cubic (3C-SiC) and hexagonal structure (2H-SiC) phases were detected by X-ray diffraction (XRD) analysis. High density stacking faults were observed in both the cylindrical and bamboo shaped nanowires which were perpendicular to their axial direction. Selected area electron diffraction (SAED) patterns of the cylindrical and bamboo shaped SiC nanowires both in the perpendicular and parallel direction to the axial direction were equivalent in the structure. After calculation and remodeling, it has been found that the SAED patterns were composed of two sets of diffraction patterns, corresponding to 2H-SiC and 3C-SiC, respectively. Therefore, it could be concluded that the SiC nanowires are composed of a large number of small fragments that are formed by hybrid 3C-SiC and 2H-SiC structures.

Taste enhancement in food gels: Effect of fracture properties on oral breakdown, bolus formation and sweetness intensity

This study investigates the effects of fracture strain and fracture stress on oral breakdown, bolus formation and sweetness intensity of semi-solid food gels containing sucrose heterogeneously distributed in layers.The sweetness intensity of gels was mainly affected by the total surface area of gel fragments formed upon chewing. Gels with low values of fracture strain and fracture stress broke down into a large number of small fragments. These gels were perceived sweeter than gels with high values of fracture strain and fracture stress. Fracture strain had a larger impact on oral breakdown behavior and sweetness intensity than fracture stress. Results indicate that the oral breakdown behavior (i.e. formation of a large number of small fragments, which leads to an increase in the total surface area) is the driving factor for taste perception in semi-solid gels that have a heterogeneous distribution of sucrose.We suggest that the differences in sweetness intensity in gels containing sucrose heterogeneously distributed in layers and differing in fracture properties result from differences in the frequency of stimulation of taste receptors. An increase in the total surface area of fragments containing sucrose facilitates the release of tastants and increases the frequency of stimulation of taste receptors. Consequently, the taste intensity of gels is enhanced.

Forest Fragmentation and Its Potential Implications in the Brazilian Amazon between 2001 and 2010

In recent decades, human development pressures have results in conversions of vast tracts of Amazonian tropical rain forests to agriculture and other human land uses. In addition to the loss of large forest cover, remaining forests are also fragmented into smaller habitats. Fragmented forests suffer several biological and ecological changes due to edge effects that can exacerbate regional forest degradation. The Brazilian Amazon has had greatly contrasting land cover dynamics in the past decade with the highest historical rates of deforestation (2001-2005) followed by the lowest rates of forest loss in decades, since 2006. Currently, the basin-wide status and implications of forest fragmentation on remnant forests is not well known. We performed a regional forest fragmentation analysis for seven states of the Brazilian Amazon between 2001 and 2010 using a recent deforestation data. During this period, the number of forest fragments (>2 ha) doubled, nearly 125,000 fragments were formed by human activities with more than 50% being smaller than 10 ha. Over the decade, forest edges increased by an average of 36,335 km/year. However, the rate was much greater from 2001-2005 (50,046 km/year) then 2006-2010 (25,365 km/year) when deforestation rates dropped drastically. In 2010, 55% of basin-wide forest edges were < 10 years old due to the creation of large number of small fragments where intensive biological and ecological degradation is ongoing. Over the past decade protected areas have been expanded dramatically over the Brazilian Amazon and, as of 2010, 51% of remaining forests across the basin are within protected areas and only 1.5% of protected areas has been deforested. Conversely, intensive forest cover conversion has been occurred in unprotected forests. While 17% of Amazonian forests are within 1 km of forest edges in 2010, the proportion increases to 34% in unprotected areas varying between 14% and 95% among the studied states. Our results indicate that the Brazilian Amazon now largely consists of two contrasting forest conditions: protected areas with vast undisturbed forests and unprotected forests that are highly fragmented and disturbed landscapes.

Effect of gel texture and sucrose spatial distribution on sweetness perception

Layered gels differing in mechanical and breakdown properties (soft, medium and hard gels) and in the distribution of sucrose in the matrix (homogeneous and inhomogeneous distributions) were used to investigate the effects of texture and spatial distribution of sucrose on sweetness perception. Rating tests, 2-Alternative forced choice tests and time-intensity analysis were performed to compare the sweetness of soft, medium and hard gels with homogeneous and inhomogeneous distributions of sucrose. Results showed that all gels with an inhomogeneous distribution of sucrose were perceived sweeter than gels in which sucrose was homogeneously distributed. This indicates that the enhancement of sweetness by an inhomogeneous distribution of sucrose does not depend on the texture of the gel matrix. Furthermore, the time-intensity profiling showed that soft gels, which had low values of fracture strain and fracture stress and broke down in a large number of small fragments upon chewing, had the highest sweetness intensity. The time required to reach the maximum sweetness intensity tended to be shorter in soft gels. These findings suggest that the breakdown behavior of the gel matrix during oral processing affects the perception of sweetness of layered gels.

Cloud Fragmentation and Proplyd-like Features in HiiRegions Imaged by theHubble Space Telescope

We have analyzed Hubble Space Telescope ACS and WFPC2 new and archival images of eight H II regions to look for new protoplanetary disks (proplyds) similar to those found in the Orion Nebula. We find a wealth of features similar in size (although many are larger) to the bright cusps around the Orion Nebula proplyds. None of them, however, contains a definitive central star. From this, we deduce that the new cusps may not be proplyds but instead fragments of molecular cloud material. Out of all the features found in the eight H II regions examined, only one, an apparent edge-on silhouette in M17, may have a central star. This feature might join the small number of bona fide proplyds found outside the Orion Nebula, in M8, M20, and possibly M16. In line with the results found recently by Smith et al., the paucity of proplyds outside the Orion Nebula can be explained by their transient nature, as well as by the specific environmental conditions under which they can be observed. Several fragments are seen as dark silhouettes against a bright background. We have reanalyzed those found in IC 2944 by Reipurth et al. and found new, similar ones in M16. None of these fragments contains a central star, and we exclude the possibility that they are disks. Reipurth et al. concluded that the IC 2944 silhouettes are not star forming. We argue here that their assumption of a constant optical depth for these fragments is not physical and that it is more likely that these fragments are star forming, a condition that is supported, although not proved, by their shapes and distributions. The process of cloud fragmentation and photoevaporation produces a large number of small fragments, while the size hierarchy expected in a photoevaporative environment would not favor small fragments. The size distributions observed will constrain any future theories of cloud fragmentation. One bright microjet candidate is found in M17, protruding from a large, limb-brightened fragment. A second, larger, jetlike feature, similar in shape and size to a Herbig-Haro jet, is found in Pismis 24. No central star appears to be associated with either of these jet candidates.

Coulomb instability of multicharged proteins

We studied the energetics and fragmentation patterns of multicharged (A +) n Morse clusters ( n = 55–321), with a total cluster charge Z = n. The Morse pair-potential parameters were characterized by the dissociation energy D = 1–10 eV, range parameter α = 1–3 Å −1, and interatomic equilibrium separation R e = 1–3 Å. The potential energies ɛ (per particle) of these multicharged Morse clusters at their equilibrium configuration (with bond length r 0) were analyzed in terms of the liquid drop model. This resulted in the relation ε = ( a ¯ C 0 / r 0 ) n 2 / 3 + ( a ¯ v 0 D / α r 0 ) + [ a ¯ s 0 D / ( α r 0 ) 3 / 2 ] n − 1 / 3 , where the reduced parameters a ¯ C 0 (for the Coulomb energy), a ¯ v 0 (for the interior energy) and a ¯ s 0 (for the surface energy) are independent of the Morse pair-potential parameters. The Rayleigh fissibility parameter X = E(Coulomb)/2 E(surface), which determines the fragmentation pattern (i.e., X < 1 for cluster fission and X > 1 for Coulomb explosion), was expressed in the form X = ( Z 2 / n ) [ ( 2 a ¯ s 0 / a ¯ C 0 ) ( D / α 3 / 2 r 0 1 / 2 ) ] − 1 . The application of this result to the Coulomb instability of multicharged globular proteins reveals that X < 1 for the currently available data. The dominating fragmentation channel is expected to involve spatially anisotropic protein fission into a small number of large fragments, rather than spatially isotropic protein Coulomb explosion into a large number of small fragments.

Percolative Fragmentation of Char Particles during Gasification

Percolative fragmentation was confirmed to occur during gasification of three microporous coal chars. Indirect evidence obtained by the variation of electrical resistivity (ER) with conversion was supported by direct observation of numerous fragments during gasification. The resistivity increases slowly at low conversions and then sharply after a certain conversion value, which is a typical percolation phenomenon suggesting the occurrence of internal fragmentation at high conversion. Two percolation models are applied to interpret the experimental data and determine the percolation threshold. A percolation threshold of 0.02-0.07 was found, corresponding to a critical conversion of 92-96% for fragmentation. The electrical resistivity variation at high conversions is found to be very sensitive to diffusional effects during gasification. Partially burnt samples with a narrow initial particle size range were also observed microscopically, and found to yield a large number of small fragments even when the particles showed no disintegration and chemical control prevailed. It is proposed that this is due to the separation of isolated clusters from the particle surface. The particle size distribution of the fragments was essentially independent of the reaction conditions and the char type, and supported the prediction by percolation theory that the number fraction distribution varies linearly with mass in a log-log plot. The results imply that perimeter fragmentation would occur in practical combustion systems in which the reactions are strongly diffusion affected.

The Khotan Dharmapada

The famous manuscript in Kharoṣṭhī script which contains an anthology of Buddhist verses similar to the Sanskrit Udānavarga and the Pali Dhammapada became known first in 1892, when portions came into the hands of MM. Dutreuil de Rhins and Grenard in Khotan. They were told that the MS. had been found in the ruins of the Vihāra at the Gośṛnga hill (on this site see M. A. Stein, Ancient Khotan, pp. 185 ff.). Other portions were acquired by the Russian Consul-General in Kashghar, M. N. Th. Petrovskii, and were sent by him to M. S. F. Oldenburg in St. Petersburg in February, 1897. In the same year, 1897, M. Oldenburg prepared a photograph and transcription of one folio of the St. Petersburg collection, which was published and presented by the Oriental Faculty of the University of St. Petersburg to the Eleventh International Congress of Orientalists held in Paris in 1897 (Predvaritel'naja zametka o buddijskoj rukopisi, napisannoj pismenami Kharoṣṭhī, St. Petersburg). Meantime, also in 1897, the portions of the MS. which had been brought to Paris were placed in the hands of M. Émile Senart, who published his reading and interpretation of the MS., with five facsimiles, in the Journal Asiatique (1898, ii, pp. 193–308). He used in addition to the text published in facsimile a large number of small fragments, and was also able to add the readings of that part of the St. Petersburg manuscript which contained half-lines fitting into his fragment B. M. Senart remarked that the portion of the MS. in St. Petersburg was more extensive and better preserved than the portion in Paris.

Mass-Spectrograph Study of the Ionization and Dissociation by Electron Impact of n-Octane

A mass-spectrograph study of n-octane (C8H18) indicates that when bombarded by 120 e-volt electrons, it dissociates into a large number of small fragments, of which those containing two or three carbon atoms (and some hydrogen) are most numerous. Ions containing odd numbers of H atoms are produced in larger quantities than those containing even numbers. The octane molecule displays a greater tendency to break up than does benzene (reported in a previous paper), which is in accordance with the reactions of these compounds in gaseous electrical discharges.