Fabrication of ordered arrays of micro- and nanoscale features with control over their shape and size via templated solid-state dewetting.

PubMed

Ye, Jongpil

2015-05-08

Templated solid-state dewetting of single-crystal films has been shown to be used to produce regular patterns of various shapes. However, the materials for which this patterning method is applicable, and the size range of the patterns produced are still limited. Here, it is shown that ordered arrays of micro- and nanoscale features can be produced with control over their shape and size via solid-state dewetting of patches patterned from single-crystal palladium and nickel films of different thicknesses and orientations. The shape and size characteristics of the patterns are found to be widely controllable with varying the shape, width, thickness, and orientation of the initial patches. The morphological evolution of the patches is also dependent on the film material, with different dewetting behaviors observed in palladium and nickel films. The mechanisms underlying the pattern formation are explained in terms of the influence on Rayleigh-like instability of the patch geometry and the surface energy anisotropy of the film material. This mechanistic understanding of pattern formation can be used to design patches for the precise fabrication of micro- and nanoscale structures with the desired shapes and feature sizes.

Fabrication of ordered arrays of micro- and nanoscale features with control over their shape and size via templated solid-state dewetting

PubMed Central

Ye, Jongpil

2015-01-01

Templated solid-state dewetting of single-crystal films has been shown to be used to produce regular patterns of various shapes. However, the materials for which this patterning method is applicable, and the size range of the patterns produced are still limited. Here, it is shown that ordered arrays of micro- and nanoscale features can be produced with control over their shape and size via solid-state dewetting of patches patterned from single-crystal palladium and nickel films of different thicknesses and orientations. The shape and size characteristics of the patterns are found to be widely controllable with varying the shape, width, thickness, and orientation of the initial patches. The morphological evolution of the patches is also dependent on the film material, with different dewetting behaviors observed in palladium and nickel films. The mechanisms underlying the pattern formation are explained in terms of the influence on Rayleigh-like instability of the patch geometry and the surface energy anisotropy of the film material. This mechanistic understanding of pattern formation can be used to design patches for the precise fabrication of micro- and nanoscale structures with the desired shapes and feature sizes. PMID:25951816

Rainbow Fourier Transform

NASA Technical Reports Server (NTRS)

Alexandrov, Mikhail D.; Cairns, Brian; Mishchenko, Michael I.

2012-01-01

We present a novel technique for remote sensing of cloud droplet size distributions. Polarized reflectances in the scattering angle range between 135deg and 165deg exhibit a sharply defined rainbow structure, the shape of which is determined mostly by single scattering properties of cloud particles, and therefore, can be modeled using the Mie theory. Fitting the observed rainbow with such a model (computed for a parameterized family of particle size distributions) has been used for cloud droplet size retrievals. We discovered that the relationship between the rainbow structures and the corresponding particle size distributions is deeper than it had been commonly understood. In fact, the Mie theory-derived polarized reflectance as a function of reduced scattering angle (in the rainbow angular range) and the (monodisperse) particle radius appears to be a proxy to a kernel of an integral transform (similar to the sine Fourier transform on the positive semi-axis). This approach, called the rainbow Fourier transform (RFT), allows us to accurately retrieve the shape of the droplet size distribution by the application of the corresponding inverse transform to the observed polarized rainbow. While the basis functions of the proxy-transform are not exactly orthogonal in the finite angular range, this procedure needs to be complemented by a simple regression technique, which removes the retrieval artifacts. This non-parametric approach does not require any a priori knowledge of the droplet size distribution functional shape and is computationally fast (no look-up tables, no fitting, computations are the same as for the forward modeling).

Universality of fragment shapes.

PubMed

Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

2015-03-16

The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

Universality of fragment shapes

PubMed Central

Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

2015-01-01

The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

Mass size distribution of particle-bound water

NASA Astrophysics Data System (ADS)

Canepari, S.; Simonetti, G.; Perrino, C.

2017-09-01

The thermal-ramp Karl-Fisher method (tr-KF) for the determination of PM-bound water has been applied to size-segregated PM samples collected in areas subjected to different environmental conditions (protracted atmospheric stability, desert dust intrusion, urban atmosphere). This method, based on the use of a thermal ramp for the desorption of water from PM samples and the subsequent analysis by the coulometric KF technique, had been previously shown to differentiate water contributes retained with different strength and associated to different chemical components in the atmospheric aerosol. The application of the method to size-segregated samples has revealed that water showed a typical mass size distribution in each one of the three environmental situations that were taken into consideration. A very similar size distribution was shown by the chemical PM components that prevailed during each event: ammonium nitrate in the case of atmospheric stability, crustal species in the case of desert dust, road-dust components in the case of urban sites. The shape of the tr-KF curve varied according to the size of the collected particles. Considering the size ranges that better characterize the event (fine fraction for atmospheric stability, coarse fraction for dust intrusion, bi-modal distribution for urban dust), this shape is coherent with the typical tr-KF shape shown by water bound to the chemical species that predominate in the same PM size range (ammonium nitrate, crustal species, secondary/combustion species - road dust components).

Comparing apples and pears: women's perceptions of their body size and shape.

PubMed

Thoma, Marie E; Hediger, Mary L; Sundaram, Rajeshwari; Stanford, Joseph B; Peterson, C Matthew; Croughan, Mary S; Chen, Zhen; Buck Louis, Germaine M

2012-10-01

Obesity is a growing public health problem among reproductive-aged women, with consequences for chronic disease risk and reproductive and obstetric morbidities. Evidence also suggests that body shape (i.e., regional fat distribution) may be independently associated with risk, yet it is not known if women adequately perceive their shape. This study aimed to assess the validity of self-reported body size and shape figure drawings when compared to anthropometric measures among reproductive-aged women. Self-reported body size was ascertained using the Stunkard nine-level figures and self-reported body shape using stylized pear, hourglass, rectangle, and apple figures. Anthropometry was performed by trained researchers. Body size and body mass index (BMI) were compared using Spearman's correlation coefficient. Fat distribution indicators were compared across body shapes for nonobese and obese women using analysis of variance (ANOVA) and Fisher's exact test. Percent agreement and kappa statistics were computed for apple and pear body shapes. The 131 women studied were primarily Caucasian (81%), aged 32 years, with a mean BMI of 27.1 kg/m(2) (range 16.6-52.8 kg/m(2)). The correlation between body size and BMI was 0.85 (p<0.001). Among nonobese women, waist-to-hip ratios (WHR) were 0.75, 0.75, 0.80, and 0.82 for pear, hourglass, rectangle, and apple, respectively (p<0.001). Comparing apples and pears, the percent agreement (kappa) for WHR≥0.80 was 83% (0.55). Self-reported size and shape were consistent with anthropometric measures commonly used to assess obesity and fat distribution, respectively. Self-reported body shape may be a useful proxy measure in addition to body size in large-scale surveys.

Minimum Temperatures, Diurnal Temperature Ranges and Temperature Inversions in Limestone Sinkholes of Different Sizes and Shapes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whiteman, Charles D.; Haiden, Thomas S.; Pospichal, Bernhard

2004-08-01

Air temperature data from five enclosed limestone sinkholes of various sizes and shapes on the 1300 m MSL Duerrenstein Plateau near Lunz, Austria have been analyzed to determine the effect of sinkhole geometry on temperature minima, diurnal temperature ranges, temperature inversion strengths and vertical temperature gradients. Data were analyzed for a non-snow-covered October night and for a snow-covered December night when the temperature fell as low as -28.5°C. Surprisingly, temperatures were similar in two sinkholes with very different drainage areas and depths. A three-layer model was used to show that the sky-view factor is the most important topographic parameter controllingmore » cooling for basins in this size range and that the cooling slows when net longwave radiation at the floor of the sinkhole is nearly balanced by the ground heat flux.« less

Estimating the settling velocity of bioclastic sediment using common grain-size analysis techniques

USGS Publications Warehouse

Cuttler, Michael V. W.; Lowe, Ryan J.; Falter, James L.; Buscombe, Daniel D.

2017-01-01

Most techniques for estimating settling velocities of natural particles have been developed for siliciclastic sediments. Therefore, to understand how these techniques apply to bioclastic environments, measured settling velocities of bioclastic sedimentary deposits sampled from a nearshore fringing reef in Western Australia were compared with settling velocities calculated using results from several common grain-size analysis techniques (sieve, laser diffraction and image analysis) and established models. The effects of sediment density and shape were also examined using a range of density values and three different models of settling velocity. Sediment density was found to have a significant effect on calculated settling velocity, causing a range in normalized root-mean-square error of up to 28%, depending upon settling velocity model and grain-size method. Accounting for particle shape reduced errors in predicted settling velocity by 3% to 6% and removed any velocity-dependent bias, which is particularly important for the fastest settling fractions. When shape was accounted for and measured density was used, normalized root-mean-square errors were 4%, 10% and 18% for laser diffraction, sieve and image analysis, respectively. The results of this study show that established models of settling velocity that account for particle shape can be used to estimate settling velocity of irregularly shaped, sand-sized bioclastic sediments from sieve, laser diffraction, or image analysis-derived measures of grain size with a limited amount of error. Collectively, these findings will allow for grain-size data measured with different methods to be accurately converted to settling velocity for comparison. This will facilitate greater understanding of the hydraulic properties of bioclastic sediment which can help to increase our general knowledge of sediment dynamics in these environments.

Derivation and Application of a Global Albedo yielding an Optical Brightness To Physical Size Transformation Free of Systematic Errors

NASA Technical Reports Server (NTRS)

Mulrooney, Dr. Mark K.; Matney, Dr. Mark J.

2007-01-01

Orbital object data acquired via optical telescopes can play a crucial role in accurately defining the space environment. Radar systems probe the characteristics of small debris by measuring the reflected electromagnetic energy from an object of the same order of size as the wavelength of the radiation. This signal is affected by electrical conductivity of the bulk of the debris object, as well as its shape and orientation. Optical measurements use reflected solar radiation with wavelengths much smaller than the size of the objects. Just as with radar, the shape and orientation of an object are important, but we only need to consider the surface electrical properties of the debris material (i.e., the surface albedo), not the bulk electromagnetic properties. As a result, these two methods are complementary in that they measure somewhat independent physical properties to estimate the same thing, debris size. Short arc optical observations such as are typical of NASA's Liquid Mirror Telescope (LMT) give enough information to estimate an Assumed Circular Orbit (ACO) and an associated range. This information, combined with the apparent magnitude, can be used to estimate an "absolute" brightness (scaled to a fixed range and phase angle). This absolute magnitude is what is used to estimate debris size. However, the shape and surface albedo effects make the size estimates subject to systematic and random errors, such that it is impossible to ascertain the size of an individual object with any certainty. However, as has been shown with radar debris measurements, that does not preclude the ability to estimate the size distribution of a number of objects statistically. After systematic errors have been eliminated (range errors, phase function assumptions, photometry) there remains a random geometric albedo distribution that relates object size to absolute magnitude. Measurements by the LMT of a subset of tracked debris objects with sizes estimated from their radar cross sections indicate that the random variations in the albedo follow a log-normal distribution quite well. In addition, this distribution appears to be independent of object size over a considerable range in size. Note that this relation appears to hold for debris only, where the shapes and other properties are not primarily the result of human manufacture, but of random processes. With this information in hand, it now becomes possible to estimate the actual size distribution we are sampling from. We have identified two characteristics of the space debris population that make this process tractable and by extension have developed a methodology for performing the transformation.

Preparation and characterization of Ba0.2Sr0.2La0.6MnO3 nanoparticles and investigation of size & shape effect on microwave absorption

NASA Astrophysics Data System (ADS)

Peymanfar, Reza; Javanshir, Shahrzad

2017-06-01

In this paper, the design and characterization of a radar absorbing material (RAM) was investigated at microwave frequency. Ba0.2Sr0.2La0.6MnO3 magnetic nanoparticles was synthesized thru a facile hydrothermal method in the presence of polymethyl methacrylate (PMMA) and the possibility of shape and size-controlled synthesis of nanoparticles (NPs) over the range 15-50 Nm was also explored. Afterward, the effect of shape and size of the synthesized Ba0.2Sr0.2La0.6MnO3 NPs on microwave absorption properties was investigated in KU-band. The crystal structures and morphology of as-synthesized nanoparticles were characterized and confirmed by FESEM, XRD, VSM, FTIR analysis. The RAM samples were prepared by dispersion of magnetic NPs in silicone rubber in an ultrasonic bath. The maximum reflection loss (RL) values NPs were 12.04 dB at 14.82 GHz and a broad absorption band (over 1.22 GHz) with RL values <-10 dB are obtained and the maximum reflection loss (RL) values of decrease and shaped NPs were 22.36 dB at 14.78 GHz and a broad absorption band (over 2.67 GHz) with RL values <-10 dB are obtained. The results indicated that the particle size and shape play a major role on the absorption properties of the composites in the 12.4-18 GHz frequency range. It is observed that microwave absorption properties increased with the decrease in average particle size of NPs.

3D-Printed Visceral Aneurysm Models Based on CT Data for Simulations of Endovascular Embolization: Evaluation of Size and Shape Accuracy.

PubMed

Shibata, Eisuke; Takao, Hidemasa; Amemiya, Shiori; Ohtomo, Kuni

2017-08-01

The objective of this study is to verify the accuracy of 3D-printed hollow models of visceral aneurysms created from CT angiography (CTA) data, by evaluating the sizes and shapes of aneurysms and related arteries. From March 2006 to August 2015, 19 true visceral aneurysms were embolized via interventional radiologic treatment provided by the radiology department at our institution; aneurysms with bleeding (n = 3) or without thin-slice (< 1 mm) preembolization CT data (n = 1) were excluded. A total of 15 consecutive true visceral aneurysms from 11 patients (eight women and three men; mean age, 61 years; range, 53-72 years) whose aneurysms were embolized via endovascular procedures were included in this study. Three-dimensional-printed hollow models of aneurysms and related arteries were fabricated from CTA data. The accuracies of the sizes and shapes of the 3D-printed hollow models were evaluated using the nonparametric Wilcoxon signed rank test and the Dice coefficient index. Aneurysm sizes ranged from 138 to 18,691 mm 3 (diameter, 6.1-35.7 mm), and no statistically significant difference was noted between patient data and 3D-printed models (p = 0.56). Shape analysis of whole aneurysms and related arteries indicated a high level of accuracy (Dice coefficient index value, 84.2-95.8%; mean [± SD], 91.1 ± 4.1%). The sizes and shapes of 3D-printed hollow visceral aneurysm models created from CTA data were accurate. These models can be used for simulations of endovascular treatment and precise anatomic information.

SU-D-201-04: Study On the Impact of Tumor Shape and Size On Drug Delivery to Pancreatic Tumors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soltani, M; Bazmara, H; Sefidgar, M

Purpose: Drug delivery to solid tumors can be expressed physically using transport phenomena such as convection and diffusion for the drug of interest within extracellular matrices. We aimed to carefully model these phenomena, and to investigate the effect of tumor shape and size on drug delivery to solid tumors in the pancreas. Methods: In this study, multiple tumor geometries as obtained from clinical PET/CT images were considered. An advanced numerical method was used to simultaneously solve fluid flow and solute transport equations. Data from n=45 pancreatic cancer patients with non-resectable locoregional disease were analyzed, and geometrical information from the tumorsmore » including size, shape, and aspect ratios were classified. To investigate effect of tumor shape, tumors with similar size but different shapes were selected and analyzed. Moreover, to investigate effect of tumor size, tumors with similar shapes but different sizes, ranging from 1 to 77 cm{sup 3}, were selected and analyzed. A hypothetical tumor similar to one of the analyzed tumors, but scaled to reduce its size below 0.2 cm{sup 3}, was also analyzed. Results: The results showed relatively similar average drug concentration profiles in tumors with different sizes. Generally, smaller tumors had higher absolute drug concentration. In the hypothetical tumor, with volume less than 0.2 cm{sup 3}, the average drug concentration was 20% higher in comparison to its counterparts. For the various real tumor geometries, however, the maximum difference between average drug concentrations was 10% for the smallest and largest tumors. Moreover, the results demonstrated that for pancreatic tumors the shape is not significant. The negligible difference of drug concentration in different tumor shapes was due to the minimum effect of convection in pancreatic tumors. Conclusion: In tumors with different sizes, smaller tumors have higher drug delivery; however, the impact of tumor shape in the case of pancreatic tumors is not significant.« less

Wing shape allometry and aerodynamics in calopterygid damselflies: a comparative approach.

PubMed

Outomuro, David; Adams, Dean C; Johansson, Frank

2013-06-07

Wing size and shape have important aerodynamic implications on flight performance. We explored how wing size was related to wing shape in territorial males of 37 taxa of the damselfly family Calopterygidae. Wing coloration was also included in the analyses because it is sexually and naturally selected and has been shown to be related to wing shape. We studied wing shape using both the non-dimensional radius of the second moment of wing area (RSM) and geometric morphometrics. Lower values of the RSM result in less energetically demanding flight and wider ranges of flight speed. We also re-analyzed previously published data on other damselflies and dragonflies. The RSM showed a hump-shaped relationship with wing size. However, after correcting for phylogeny using independent contrast, this pattern changed to a negative linear relationship. The basal genus of the study family, Hetaerina, was mainly driving that change. The obtained patterns were specific for the study family and differed from other damselflies and dragonflies. The relationship between the RSM and wing shape measured by geometric morphometrics was linear, but relatively small changes along the RSM axis can result in large changes in wing shape. Our results also showed that wing coloration may have some effect on RSM. We found that RSM showed a complex relationship with size in calopterygid damselflies, probably as a result of other selection pressures besides wing size per se. Wing coloration and specific behavior (e.g. courtship) are potential candidates for explaining the complexity. Univariate measures of wing shape such as RSM are more intuitive but lack the high resolution of other multivariate techniques such as geometric morphometrics. We suggest that the relationship between wing shape and size are taxa-specific and differ among closely-related insect groups.

Platinum and palladium nano-structured catalysts for polymer electrolyte fuel cells and direct methanol fuel cells.

PubMed

Long, Nguyen Viet; Thi, Cao Minh; Yong, Yang; Nogami, Masayuki; Ohtaki, Michitaka

2013-07-01

In this review, we present the synthesis and characterization of Pt, Pd, Pt based bimetallic and multi-metallic nanoparticles with mixture, alloy and core-shell structure for nano-catalysis, energy conversion, and fuel cells. Here, Pt and Pd nanoparticles with modified nanostructures can be controllably synthesized via chemistry and physics for their uses as electro-catalysts. The cheap base metal catalysts can be studied in the relationship of crystal structure, size, morphology, shape, and composition for new catalysts with low cost. Thus, Pt based alloy and core-shell catalysts can be prepared with the thin Pt and Pt-Pd shell, which are proposed in low and high temperature proton exchange membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs). We also present the survey of the preparation of Pt and Pd based catalysts for the better catalytic activity, high durability, and stability. The structural transformations, quantum-size effects, and characterization of Pt and Pd based catalysts in the size ranges of 30 nm (1-30 nm) are presented in electro-catalysis. In the size range of 10 nm (1-10 nm), the pure Pt catalyst shows very large surface area for electro-catalysis. To achieve homogeneous size distribution, the shaped synthesis of the polyhedral Pt nanoparticles is presented. The new concept of shaping specific shapes and morphologies in the entire nano-scale from nano to micro, such as polyhedral, cube, octahedra, tetrahedra, bar, rod, and others of the nanoparticles is proposed, especially for noble and cheap metals. The uniform Pt based nanosystems of surface structure, internal structure, shape, and morphology in the nanosized ranges are very crucial to next fuel cells. Finally, the modifications of Pt and Pd based catalysts of alloy, core-shell, and mixture structures lead to find high catalytic activity, durability, and stability for nano-catalysis, energy conversion, fuel cells, especially the next large-scale commercialization of next PEMFCs, and DMFCs.

Parameterization of Photon Tunneling with Application to Ice Cloud Optical Properties at Terrestrial Wavelengths

NASA Astrophysics Data System (ADS)

Mitchell, D. L.

2006-12-01

Sometimes deep physical insights can be gained through the comparison of two theories of light scattering. Comparing van de Hulst's anomalous diffraction approximation (ADA) with Mie theory yielded insights on the behavior of the photon tunneling process that resulted in the modified anomalous diffraction approximation (MADA). (Tunneling is the process by which radiation just beyond a particle's physical cross-section may undergo large angle diffraction or absorption, contributing up to 40% of the absorption when wavelength and particle size are comparable.) Although this provided a means of parameterizing the tunneling process in terms of the real index of refraction and size parameter, it did not predict the efficiency of the tunneling process, where an efficiency of 100% is predicted for spheres by Mie theory. This tunneling efficiency, Tf, depends on particle shape and ranges from 0 to 1.0, with 1.0 corresponding to spheres. Similarly, by comparing absorption efficiencies predicted by the Finite Difference Time Domain Method (FDTD) with efficiencies predicted by MADA, Tf was determined for nine different ice particle shapes, including aggregates. This comparison confirmed that Tf is a strong function of ice crystal shape, including the aspect ratio when applicable. Tf was lowest (< 0.36) for aggregates and plates, and largest (> 0.9) for quasi- spherical shapes. A parameterization of Tf was developed in terms of (1) ice particle shape and (2) mean particle size regarding the large mode (D > 70 mm) of the ice particle size distribution. For the small mode, Tf is only a function of ice particle shape. When this Tf parameterization is used in MADA, absorption and extinction efficiency differences between MADA and FDTD are within 14% over the terrestrial wavelength range 3-100 mm for all size distributions and most crystal shapes likely to be found in cirrus clouds. Using hyperspectral radiances, it is demonstrated that Tf can be retrieved from ice clouds. Since Tf is a function of ice particle shape, this may provide a means of retrieving qualitative information on ice particle shape.

The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials.

PubMed

Dunne, Peter W; Starkey, Chris L; Gimeno-Fabra, Miquel; Lester, Edward H

2014-02-21

Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.

Absorption Efficiencies of Forsterite. I: DDA Explorations in Grain Shape and Size

NASA Technical Reports Server (NTRS)

Lindsay, Sean S.; Wooden, Diane; Harker, David E.; Kelley, Michael S.; Woodward, Charles E.; Murphy, Jim R.

2013-01-01

We compute the absorption efficiency (Q(sub abs)) of forsterite using the discrete dipole approximation (DDA) in order to identify and describe what characteristics of crystal grain shape and size are important to the shape, peak location, and relative strength of spectral features in the 8 - 40 micron wavelength range. Using the DDSCAT code, we compute Q(sub abs) for non-spherical polyhedral grain shapes with a(sub eff) = 0.1 micron. The shape characteristics identified are: 1) elongation/reduction along one of three crystallographic axes; 2) asymmetry, such that all three crystallographic axes are of different lengths; and 3) the presence of crystalline faces that are not parallel to a specific crystallographic axis, e.g., non-rectangular prisms and (di)pyramids. Elongation/reduction dominates the locations and shapes of spectral features near 10, 11, 16, 23.5, 27, and 33.5 micron, while asymmetry and tips are secondary shape effects. Increasing grain sizes (0.1 - 1.0 micron) shifts the 10, 11 micron features systematically towards longer wavelengths and relative to the 11 micron feature increases the strengths and slightly broadens the longer wavelength features. Seven spectral shape classes are established for crystallographic a-, b-, and c-axes and include columnar and platelet shapes plus non-elongated or equant grain shapes. The spectral shape classes and the effects of grain size have practical application in identifying or excluding columnar, platelet or equant forsterite grain shapes in astrophysical environs. Identification of the shape characteristics of forsterite from 8 - 40 micron spectra provides a potential means to probe the temperatures at which forsterite formed.

Marine extinction risk shaped by trait-environment interactions over 500 million years.

PubMed

Orzechowski, Emily A; Lockwood, Rowan; Byrnes, Jarrett E K; Anderson, Sean C; Finnegan, Seth; Finkel, Zoe V; Harnik, Paul G; Lindberg, David R; Liow, Lee Hsiang; Lotze, Heike K; McClain, Craig R; McGuire, Jenny L; O'Dea, Aaron; Pandolfi, John M; Simpson, Carl; Tittensor, Derek P

2015-10-01

Perhaps the most pressing issue in predicting biotic responses to present and future global change is understanding how environmental factors shape the relationship between ecological traits and extinction risk. The fossil record provides millions of years of insight into how extinction selectivity (i.e., differential extinction risk) is shaped by interactions between ecological traits and environmental conditions. Numerous paleontological studies have examined trait-based extinction selectivity; however, the extent to which these patterns are shaped by environmental conditions is poorly understood due to a lack of quantitative synthesis across studies. We conducted a meta-analysis of published studies on fossil marine bivalves and gastropods that span 458 million years to uncover how global environmental and geochemical changes covary with trait-based extinction selectivity. We focused on geographic range size and life habit (i.e., infaunal vs. epifaunal), two of the most important and commonly examined predictors of extinction selectivity. We used geochemical proxies related to global climate, as well as indicators of ocean acidification, to infer average global environmental conditions. Life-habit selectivity is weakly dependent on environmental conditions, with infaunal species relatively buffered from extinction during warmer climate states. In contrast, the odds of taxa with broad geographic ranges surviving an extinction (>2500 km for genera, >500 km for species) are on average three times greater than narrow-ranging taxa (estimate of odds ratio: 2.8, 95% confidence interval = 2.3-3.5), regardless of the prevailing global environmental conditions. The environmental independence of geographic range size extinction selectivity emphasizes the critical role of geographic range size in setting conservation priorities. © 2015 John Wiley & Sons Ltd.

Self-folding with shape memory composites at the millimeter scale

NASA Astrophysics Data System (ADS)

Felton, S. M.; Becker, K. P.; Aukes, D. M.; Wood, R. J.

2015-08-01

Self-folding is an effective method for creating 3D shapes from flat sheets. In particular, shape memory composites—laminates containing shape memory polymers—have been used to self-fold complex structures and machines. To date, however, these composites have been limited to feature sizes larger than one centimeter. We present a new shape memory composite capable of folding millimeter-scale features. This technique can be activated by a global heat source for simultaneous folding, or by resistive heaters for sequential folding. It is capable of feature sizes ranging from 0.5 to 40 mm, and is compatible with multiple laminate compositions. We demonstrate the ability to produce complex structures and mechanisms by building two self-folding pieces: a model ship and a model bumblebee.

Study of various synthesis techniques of nanomaterials

NASA Astrophysics Data System (ADS)

Patil, Madhuri; Sharma, Deepika; Dive, Avinash; Mahajan, Sandeep; Sharma, Ramphal

2018-05-01

Development of synthesis techniques of realizing nano-materials over a range of sizes, shapes, and chemical compositions is an important aspect of nanotechnology. The remarkable size dependent physical & chemical properties of particles have fascinated and inspired research activity in this direction. This paper describes some aspects on synthesis and characterization of particles of metals, metal alloys, and oxides, either in the form of thin films or bulk shapes. A brief discussion on processing of thin-films is also described.

The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials

NASA Astrophysics Data System (ADS)

Dunne, Peter W.; Starkey, Chris L.; Gimeno-Fabra, Miquel; Lester, Edward H.

2014-01-01

Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control. Electronic supplementary information (ESI) available: Experimental details, refinement procedure, fluorescence spectra of ZnS samples. See DOI: 10.1039/c3nr05749f

Templated Solid-State Dewetting of Thin Silicon Films.

PubMed

Naffouti, Meher; David, Thomas; Benkouider, Abdelmalek; Favre, Luc; Delobbe, Anne; Ronda, Antoine; Berbezier, Isabelle; Abbarchi, Marco

2016-11-01

Thin film dewetting can be efficiently exploited for the implementation of functionalized surfaces over very large scales. Although the formation of sub-micrometer sized crystals via solid-state dewetting represents a viable method for the fabrication of quantum dots and optical meta-surfaces, there are several limitations related to the intrinsic features of dewetting in a crystalline medium. Disordered spatial organization, size, and shape fluctuations are relevant issues not properly addressed so far. This study reports on the deterministic nucleation and precise positioning of Si- and SiGe-based nanocrystals by templated solid-state dewetting of thin silicon films. The dewetting dynamics is guided by pattern size and shape taking full control over number, size, shape, and relative position of the particles (islands dimensions and relative distances are in the hundreds nm range and fluctuate ≈11% for the volumes and ≈5% for the positioning). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Does Height to Width Ratio Correlate with Mean Volume in Gastropods?

NASA Astrophysics Data System (ADS)

Barriga, R.; Seixas, G.; Payne, J.

2012-12-01

Marine organisms' shell shape and size show important biological information. For example, shape and size can dictate how the organism ranges for food and escapes predation. Due to lack of data and analysis, the evolution of shell size in marine gastropods (snails) remains poorly known. In this study, I attempt to find the relationship between height to width ratio and mean volume. I collected height and width measurements from primary literature sources and calculated volume from these measurements. My results indicate that there was no correlation between height to width ratio and mean volume between 500 to 200 Ma, but there was a correlation between 200 Ma to present where there is a steady increase in both height to width ratio and mean volume. This means that shell shape was not an important factor at the beginning of gastropod evolution but after 200 Ma body size evolution was increasingly driven by the height to width ratio.

Correlations between Crystallite Size, Shape, Surface, and Infrared Spectra Using the Ti-C System

NASA Astrophysics Data System (ADS)

Kimura, Y.; Ikegami, A.; Kurumada, M.; Kamitsuji, K.; Kaito, C.

2004-06-01

TiC crystallites less than 10 nm in size showed an absorption feature at 14.3 μm. This 14.3 μm absorption was rarely seen in specimens ranging from bulk material to grains of 50 nm in size. The 14.3 μm feature was weakened as a result of the growth of TiC crystallites by heat treatment. When the carbide grains were covered with a carbon layer, the absorption peaks were considerably weakened, i.e., the absorption intensity depended on the grain surface state. A possible explanation is that the effects of size and shape on the spectra depend on the surface anisotropy.

Shape, form, function and Leishmania pathogenicity: from textbook descriptions to biological understanding

PubMed Central

Gull, Keith

2017-01-01

The shape and form of protozoan parasites are inextricably linked to their pathogenicity. The evolutionary pressure associated with establishing and maintaining an infection and transmission to vector or host has shaped parasite morphology. However, there is not a ‘one size fits all’ morphological solution to these different pressures, and parasites exhibit a range of different morphologies, reflecting the diversity of their complex life cycles. In this review, we will focus on the shape and form of Leishmania spp., a group of very successful protozoan parasites that cause a range of diseases from self-healing cutaneous leishmaniasis to visceral leishmaniasis, which is fatal if left untreated. PMID:28903998

Monogenean anchor morphometry: systematic value, phylogenetic signal, and evolution

PubMed Central

Soo, Oi Yoon Michelle; Tan, Wooi Boon; Lim, Lee Hong Susan

2016-01-01

Background. Anchors are one of the important attachment appendages for monogenean parasites. Common descent and evolutionary processes have left their mark on anchor morphometry, in the form of patterns of shape and size variation useful for systematic and evolutionary studies. When combined with morphological and molecular data, analysis of anchor morphometry can potentially answer a wide range of biological questions. Materials and Methods. We used data from anchor morphometry, body size and morphology of 13 Ligophorus (Monogenea: Ancyrocephalidae) species infecting two marine mugilid (Teleostei: Mugilidae) fish hosts: Moolgarda buchanani (Bleeker) and Liza subviridis (Valenciennes) from Malaysia. Anchor shape and size data (n = 530) were generated using methods of geometric morphometrics. We used 28S rRNA, 18S rRNA, and ITS1 sequence data to infer a maximum likelihood phylogeny. We discriminated species using principal component and cluster analysis of shape data. Adams’s Kmult was used to detect phylogenetic signal in anchor shape. Phylogeny-correlated size and shape changes were investigated using continuous character mapping and directional statistics, respectively. We assessed morphological constraints in anchor morphometry using phylogenetic regression of anchor shape against body size and anchor size. Anchor morphological integration was studied using partial least squares method. The association between copulatory organ morphology and anchor shape and size in phylomorphospace was used to test the Rohde-Hobbs hypothesis. We created monogeneaGM, a new R package that integrates analyses of monogenean anchor geometric morphometric data with morphological and phylogenetic data. Results. We discriminated 12 of the 13 Ligophorus species using anchor shape data. Significant phylogenetic signal was detected in anchor shape. Thus, we discovered new morphological characters based on anchor shaft shape, the length between the inner root point and the outer root point, and the length between the inner root point and the dent point. The species on M. buchanani evolved larger, more robust anchors; those on L. subviridis evolved smaller, more delicate anchors. Anchor shape and size were significantly correlated, suggesting constraints in anchor evolution. Tight integration between the root and the point compartments within anchors confirms the anchor as a single, fully integrated module. The correlation between male copulatory organ morphology and size with anchor shape was consistent with predictions from the Rohde-Hobbs hypothesis. Conclusions. Monogenean anchors are tightly integrated structures, and their shape variation correlates strongly with phylogeny, thus underscoring their value for systematic and evolutionary biology studies. Our MonogeneaGM R package provides tools for researchers to mine biological insights from geometric morphometric data of speciose monogenean genera. PMID:26966649

Methods for Scaling Icing Test Conditions

NASA Technical Reports Server (NTRS)

Anderson, David N.

1995-01-01

This report presents the results of tests at NASA Lewis to evaluate several methods to establish suitable alternative test conditions when the test facility limits the model size or operating conditions. The first method was proposed by Olsen. It can be applied when full-size models are tested and all the desired test conditions except liquid-water content can be obtained in the facility. The other two methods discussed are: a modification of the French scaling law and the AEDC scaling method. Icing tests were made with cylinders at both reference and scaled conditions representing mixed and glaze ice in the NASA Lewis Icing Research Tunnel. Reference and scale ice shapes were compared to evaluate each method. The Olsen method was tested with liquid-water content varying from 1.3 to .8 g/m(exp3). Over this range, ice shapes produced using the Olsen method were unchanged. The modified French and AEDC methods produced scaled ice shapes which approximated the reference shapes when model size was reduced to half the reference size for the glaze-ice cases tested.

Interspecific geographic range size-body size relationship and the diversification dynamics of Neotropical furnariid birds.

PubMed

Inostroza-Michael, Oscar; Hernández, Cristián E; Rodríguez-Serrano, Enrique; Avaria-Llautureo, Jorge; Rivadeneira, Marcelo M

2018-05-01

Among the earliest macroecological patterns documented, is the range and body size relationship, characterized by a minimum geographic range size imposed by the species' body size. This boundary for the geographic range size increases linearly with body size and has been proposed to have implications in lineages evolution and conservation. Nevertheless, the macroevolutionary processes involved in the origin of this boundary and its consequences on lineage diversification have been poorly explored. We evaluate the macroevolutionary consequences of the difference (hereafter the distance) between the observed and the minimum range sizes required by the species' body size, to untangle its role on the diversification of a Neotropical species-rich bird clade using trait-dependent diversification models. We show that speciation rate is a positive hump-shaped function of the distance to the lower boundary. The species with highest and lowest distances to minimum range size had lower speciation rates, while species close to medium distances values had the highest speciation rates. Further, our results suggest that the distance to the minimum range size is a macroevolutionary constraint that affects the diversification process responsible for the origin of this macroecological pattern in a more complex way than previously envisioned. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Evaluation of a laser scanning sensor on detection of complex shaped targets for variable-rate sprayer development

USDA-ARS?s Scientific Manuscript database

Sensors that can accurately measure canopy structures are prerequisites for development of advanced variable-rate sprayers. A 270° radial range laser sensor was evaluated for its accuracy to measure dimensions of target surfaces with complex shapes and sizes. An algorithm for data acquisition and 3-...

Positional dependence of scale size and shape in butterfly wings: wing-wide phenotypic coordination of color-pattern elements and background.

PubMed

Kusaba, Kiseki; Otaki, Joji M

2009-02-01

Butterfly wing color-patterns are a phenotypically coordinated array of scales whose color is determined as cellular interpretation outputs for morphogenic signals. Here we investigated distribution patterns of scale shape and size in relation to position and coloration on the hindwings of a nymphalid butterfly Junonia orithya. Most scales had a smooth edge but scales at and near the natural and ectopic eyespot foci and in the postbasal area were jagged. Scale size decreased regularly from the postbasal to distal areas, and eyespots occasionally had larger scales than the background. Reasonable correlations were obtained between the eyespot size and focal scale size in females. Histological and real-time individual observations of the color-pattern developmental sequence showed that the background brown and blue colors expanded from the postbasal to distal areas independently from the color-pattern elements such as eyespots. These data suggest that morphogenic signals for coloration directly or indirectly influence the scale shape and size and that the blue "background" is organized by a long-range signal from an unidentified organizing center in J. orithya.

Physical characterization of fine particulate matter inside the public transit buses fueled by biodiesel in Toledo, Ohio.

PubMed

Shandilya, Kaushik K; Kumar, Ashok

2011-06-15

This study presents the physical characteristics of fine particulate matter (PM) collected inside the urban-public transit buses in Toledo, OH. These buses run on 20% biodiesel blended with ultra-low sulfur diesel (ULSD) (B20). For risk analysis, it is crucial to know the modality of the size distribution and the shape factor of PM collected inside the bus. The number-size distribution, microstructure, and aspect ratio of fine PM filter samples collected in the urban-public transit buses were measured for three years (2007-2009), using an environmental scanning electron microscope (ESEM) coupled with energy dispersive X-ray spectrometry (EDX). Only the reproducible results from repeated experiments on ESEM and size distribution obtained by the GRIMM dust monitor were used in this study. The size distribution was found bi-modal in the winter and fall months and was primarily uni-modal during spring and summer. The aspect ratio for different filter samples collected inside the bus range from 2.4 to 3.6 in average value, with standard deviation ranging from 0.9 to 7.4. The square-shaped and oblong-shaped particles represent the single inhalable particle's morphology characteristics in the air of the Toledo transit buses. Copyright © 2011 Elsevier B.V. All rights reserved.

Growth trajectories in the cave bear and its extant relatives: an examination of ontogenetic patterns in phylogeny.

PubMed

Fuchs, Manuela; Geiger, Madeleine; Stange, Madlen; Sánchez-Villagra, Marcelo R

2015-11-02

The study of postnatal ontogeny can provide insights into evolution by offering an understanding of how growth trajectories have evolved resulting in adult morphological disparity. The Ursus lineage is a good subject for studying cranial and mandibular shape and size variation in relation to postnatal ontogeny and phylogeny because it is at the same time not diverse but the species exhibit different feeding ecologies. Cranial and mandibular shapes of Ursus arctos (brown bear), U. maritimus (polar bear), U. americanus (American black bear), and the extinct U. spelaeus (cave bear) were examined, using a three-dimensional geometric morphometric approach. Additionally, ontogenetic series of crania and mandibles of U. arctos and U. spelaeus ranging from newborns to senile age were sampled. The distribution of specimens in morphospace allowed to distinguish species and age classes and the ontogenetic trajectories U. arctos and U. spelaeus were found to be more similar than expected by chance. Cranial shape changes during ontogeny are largely size related whereas the evolution of cranial shape disparity in this clade appears to be more influenced by dietary adaptation than by size and phylogeny. The different feeding ecologies are reflected in different cranial and mandibular shapes among species. The cranial and mandibular shape disparity in the Ursus lineage appears to be more influenced by adaptation to diet than by size or phylogeny. In contrast, the cranial and mandibular shape changes during postnatal ontogeny in U. arctos and U. spelaeus are probably largely size related. The patterns of morphospace occupation of the cranium and the mandible in adults and through ontogeny are different.

Arrested of coalescence of emulsion droplets of arbitrary size

NASA Astrophysics Data System (ADS)

Mbanga, Badel L.; Burke, Christopher; Blair, Donald W.; Atherton, Timothy J.

2013-03-01

With applications ranging from food products to cosmetics via targeted drug delivery systems, structured anisotropic colloids provide an efficient way to control the structure, properties and functions of emulsions. When two fluid emulsion droplets are brought in contact, a reduction of the interfacial tension drives their coalescence into a larger droplet of the same total volume and reduced exposed area. This coalescence can be partially or totally hindered by the presence of nano or micron-size particles that coat the interface as in Pickering emulsions. We investigate numerically the dependance of the mechanical stability of these arrested shapes on the particles size, their shape anisotropy, their polydispersity, their interaction with the solvent, and the particle-particle interactions. We discuss structural shape changes that can be induced by tuning the particles interactions after arrest occurs, and provide design parameters for the relevant experiments.

Scaling approach in predicting the seatbelt loading and kinematics of vulnerable occupants: How far can we go?

PubMed

Nie, Bingbing; Forman, Jason L; Joodaki, Hamed; Wu, Taotao; Kent, Richard W

2016-09-01

Occupants with extreme body size and shape, such as the small female or the obese, were reported to sustain high risk of injury in motor vehicle crashes (MVCs). Dimensional scaling approaches are widely used in injury biomechanics research based on the assumption of geometrical similarity. However, its application scope has not been quantified ever since. The objective of this study is to demonstrate the valid range of scaling approaches in predicting the impact response of the occupants with focus on the vulnerable populations. The present analysis was based on a data set consisting of 60 previously reported frontal crash tests in the same sled buck representing a typical mid-size passenger car. The tests included two categories of human surrogates: 9 postmortem human surrogates (PMHS) of different anthropometries (stature range: 147-189 cm; weight range: 27-151 kg) and 5 anthropomorphic test devices (ATDs). The impact response was considered including the restraint loads and the kinematics of multiple body segments. For each category of the human surrogates, a mid-size occupant was selected as a baseline and the impact response was scaled specifically to another subject based on either the body mass (body shape) or stature (the overall body size). To identify the valid range of the scaling approach, the scaled response was compared to the experimental results using assessment scores on the peak value, peak timing (the time when the peak value occurred), and the overall curve shape ranging from 0 (extremely poor) to 1 (perfect match). Scores of 0.7 to 0.8 and 0.8 to 1.0 indicate fair and acceptable prediction. For both ATDs and PMHS, the scaling factor derived from body mass proved an overall good predictor of the peak timing for the shoulder belt (0.868, 0.829) and the lap belt (0.858, 0.774) and for the peak value of the lap belt force (0.796, 0.869). Scaled kinematics based on body stature provided fair or acceptable prediction on the overall head/shoulder kinematics (0.741, 0.822 for the head; 0.817, 0.728 for the shoulder) regardless of the anthropometry. The scaling approach exhibited poor prediction capability on the curve shape for the restraint force (0.494 and 0.546 for the shoulder belt; 0.585 and 0.530 for the lap belt). It also cannot well predict the excursion of the pelvis and the knee. The results revealed that for the peak lap belt force and the forward motion of the head and shoulder, the underlying linear relationship with body size and shape is valid over a wide anthropometric range. The chaotic nature of the dynamic response cannot be fully recovered by the assumption of the whole-body geometrical similarity, especially for the curve shape. The valid range of the scaling approach established in this study can be reasonably referenced in predicting the impact response of a given specific population with expected deviation. Application of this knowledge also includes proposing strategies for restraint configuration and providing reference for ATD and/or human body model (HBM) development for vulnerable occupants.

Impact of patient weight on tumor visibility based on human-shaped phantom simulation study in PET imaging system

NASA Astrophysics Data System (ADS)

Musarudin, M.; Saripan, M. I.; Mashohor, S.; Saad, W. H. M.; Nordin, A. J.; Hashim, S.

2015-10-01

Energy window technique has been implemented in all positron emission tomography (PET) imaging protocol, with the aim to remove the unwanted low energy photons. Current practices in our institution however are performed by using default energy threshold level regardless of the weight of the patient. Phantom size, which represents the size of the patient's body, is the factor that determined the level of scatter fraction during PET imaging. Thus, the motivation of this study is to determine the optimum energy threshold level for different sizes of human-shaped phantom, to represent underweight, normal, overweight and obese patients. In this study, the scanner was modeled by using Monte Carlo code, version MCNP5. Five different sizes of elliptical-cylinder shaped of human-sized phantoms with diameter ranged from 15 to 30 cm were modeled. The tumor was modeled by a cylindrical line source filled with 1.02 MeV positron emitters at the center of the phantom. Various energy window widths, in the ranged of 10-50% were implemented to the data. In conclusion, the phantom mass volume did influence the scatter fraction within the volume. Bigger phantom caused more scattering events and thus led to coincidence counts lost. We evaluated the impact of phantom sizes on the sensitivity and visibility of the simulated models. Implementation of wider energy window improved the sensitivity of the system and retained the coincidence photons lost. Visibility of the tumor improved as an appropriate energy window implemented for the different sizes of phantom.

Characterization of wood dust from furniture by scanning electron microscopy and energy-dispersive x-ray analysis.

PubMed

Gómez Yepes, Milena Elizabeth; Cremades, Lázaro V

2011-01-01

Study characterized and analyzed form factor, elementary composition and particle size of wood dust, in order to understand its harmful health effects on carpenters in Quindío (Colombia). Once particle characteristics (size distributions, aerodynamic equivalent diameter (D(α)), elemental composition and shape factors) were analyzed, particles were then characterized via scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray analysis (EDXRA). SEM analysis of particulate matter showed: 1) cone-shaped particle ranged from 2.09 to 48.79 µm D(α); 2) rectangular prism-shaped particle from 2.47 to 72.9 µm D(α); 3) cylindrically-shaped particle from 2.5 to 48.79 µm D(α); and 4) spherically-shaped particle from 2.61 to 51.93 µm D(α). EDXRA reveals presence of chemical elements from paints and varnishes such as Ca, K, Na and Cr. SEM/EDXRA contributes in a significant manner to the morphological characterization of wood dust. It is obvious that the type of particles sampled is a complex function of shapes and sizes of particles. Thus, it is important to investigate the influence of particles characteristics, morphology, shapes and D(α) that may affect the health of carpenters in Quindío.

Exceptional body sizes but typical trophic structure in a Pleistocene food web.

PubMed

Segura, Angel M; Fariña, Richard A; Arim, Matías

2016-05-01

In this study, we focused on the exceptionally large mammals inhabiting the Americas during the Quaternary period and the paramount role of body size in species ecology. We evaluated two main features of Pleistocene food webs: the relationship between body size and (i) trophic position and (ii) vulnerability to predation. Despite the large range of species sizes, we found a hump-shaped relationship between trophic position and body size. We also found a negative trend in species vulnerability similar to that observed in modern faunas. The largest species lived near the boundary of energetic constraints, such that any shift in resource availability could drive these species to extinction. Our results reinforce several features of megafauna ecology: (i) the negative relationship between trophic position and body size implies that large-sized species were particularly vulnerable to changes in energetic support; (ii) living close to energetic imbalance could favour the incorporation of additional energy sources, for example, a transition from a herbivorous to a scavenging diet in the largest species (e.g. Megatherium) and (iii) the interactions and structure of Quaternary megafauna communities were shaped by similar forces to those shaping modern fauna communities. © 2016 The Author(s).

Stock discrimination of spottedtail goby ( Synechogobius ommaturus) in the Yellow Sea by analysis of otolith shape

NASA Astrophysics Data System (ADS)

Wang, Yingjun; Ye, Zhenjiang; Liu, Qun; Cao, Liang

2011-01-01

Otolith shape is species specific and is an ideal marker of fish population affiliation. In this study, otolith shape of spottedtail goby Synechogobius ommaturus is used to identify stocks in different spawning locations in the Yellow Sea. The main objectives of this study are to explore the potential existence of local stocks of spottedtail goby in the Yellow Sea by analysis of otolith shape, and to investigate ambient impacts on otolith shape. Spottedtail goby was sampled in five locations in the Yellow Sea in 2007 and 2008. Otoliths are described using variables correlated to size (otolith area, perimeter, length, width, and weight) and shape (rectangularity, circularity, and 20 Fourier harmonics). Only standardized otolith variables are used so that the effect of otolith size on the shape variables could be eliminated. There is no significant difference among variables of sex, year, and side (left and right). However, the otolith shapes of the spring stocks and the autumn stocks differ significantly. Otolith shape differences are greater among locations than between years. Correct classification rate of spottedtail goby with the otolith shape at different sampling locations range from 29.7%-77.4%.

Effect of Pore Size, Morphology and Orientation on the Bulk Stiffness of a Porous Ti35Nb4Sn Alloy

NASA Astrophysics Data System (ADS)

Torres-Sanchez, Carmen; McLaughlin, John; Bonallo, Ross

2018-04-01

The metal foams of a titanium alloy were designed to study porosity as well as pore size and shape independently. These were manufactured using a powder metallurgy/space-holder technique that allowed a fine control of the pore size and morphology; and then characterized and tested against well-established models to predict a relationship between porosity, pore size and shape, and bulk stiffness. Among the typically used correlations, existing power-law models were found to be the best fit for the prediction of macropore morphology against compressive elastic moduli, outperforming other models such as exponential, polynomial or binomial. Other traditional models such as linear ones required of updated coefficients to become relevant to metal porous sintered macrostructures. The new coefficients reported in this study contribute toward a design tool that allows the tailoring of mechanical properties through porosity macrostructure. The results show that, for the same porosity range, pore shape and orientation have a significant effect on mechanical performance and that they can be predicted. Conversely, pore size has only a mild impact on bulk stiffness.

Investigating the size, shape and surface roughness dependence of polarization lidars with light-scattering computations on real mineral dust particles: Application to dust particles' external mixtures and dust mass concentration retrievals

NASA Astrophysics Data System (ADS)

Mehri, Tahar; Kemppinen, Osku; David, Grégory; Lindqvist, Hannakaisa; Tyynelä, Jani; Nousiainen, Timo; Rairoux, Patrick; Miffre, Alain

2018-05-01

Our understanding of the contribution of mineral dust to the Earth's radiative budget is limited by the complexity of these particles, which present a wide range of sizes, are highly-irregularly shaped, and are present in the atmosphere in the form of particle mixtures. To address the spatial distribution of mineral dust and atmospheric dust mass concentrations, polarization lidars are nowadays frequently used, with partitioning algorithms allowing to discern the contribution of mineral dust in two or three-component particle external mixtures. In this paper, we investigate the dependence of the retrieved dust backscattering (βd) vertical profiles with the dust particle size and shape. For that, new light-scattering numerical simulations are performed on real atmospheric mineral dust particles, having determined mineralogy (CAL, DOL, AGG, SIL), derived from stereogrammetry (stereo-particles), with potential surface roughness, which are compared to the widely-used spheroidal mathematical shape model. For each dust shape model (smooth stereo-particles, rough stereo-particles, spheroids), the dust depolarization, backscattering Ångström exponent, lidar ratio are computed for two size distributions representative of mineral dust after long-range transport. As an output, two Saharan dust outbreaks involving mineral dust in two, then three-component particle mixtures are studied with Lyon (France) UV-VIS polarization lidar. If the dust size matters most, under certain circumstances, βd can vary by approximately 67% when real dust stereo-particles are used instead of spheroids, corresponding to variations in the dust backscattering coefficient as large as 2 Mm- 1·sr- 1. Moreover, the influence of surface roughness in polarization lidar retrievals is for the first time discussed. Finally, dust mass-extinction conversion factors (ηd) are evaluated for each assigned shape model and dust mass concentrations are retrieved from polarization lidar measurements. From spheroids to stereo-particles, ηd increases by about 30%. We believe these results may be useful for our understanding of the spatial distribution of mineral dust contained in an aerosol external mixture and to better quantify dust mass concentrations from polarization lidar experiments.

Q-space analysis of light scattering by ice crystals

NASA Astrophysics Data System (ADS)

Heinson, Yuli W.; Maughan, Justin B.; Ding, Jiachen; Chakrabarti, Amitabha; Yang, Ping; Sorensen, Christopher M.

2016-12-01

Q-space analysis is applied to extensive simulations of the single-scattering properties of ice crystals with various habits/shapes over a range of sizes. The analysis uncovers features common to all the shapes: a forward scattering regime with intensity quantitatively related to the Rayleigh scattering by the particle and the internal coupling parameter, followed by a Guinier regime dependent upon the particle size, a complex power law regime with incipient two dimensional diffraction effects, and, in some cases, an enhanced backscattering regime. The effects of significant absorption on the scattering profile are also studied. The overall features found for the ice crystals are similar to features in scattering from same sized spheres.

Synthesis of silver nano-materials from Grevillea robusta A Cunn (Silver-oak tree) leaves extract and shape directing role of cetyltrimethylammonium bromide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Rabia; Faisal, Qamer; Hussain, Sajjad

Grevillea robusta (Silver-oak tree) tree is a medicinal tree. Conventional UV-visible spectrophotometric and transmission electron microscopic technique were used to determine the morphology of silver nanoplates (AgNP) using Grevillea robusta (Silver-oak tree) aqueous leaves extract for the first time. The visible spectra showed the presence of three well defined surface plasmon absorption (SPR) bands at 500, 550 and 675 nm which was attributed to the anisotropic growth of Ag-nanoplates. Transmission electron microscopic (TEM) analysis of AgNP showed formation of truncated triangular, polyhedral with some irregular shapes nanoplates in the size range 8-20 nm. Cetyltrimethylammonium bromide (CTAB) has no significant effect on themore » shape of the spectra, position of SPR bands, size and size distribution of AgNP.« less

Au nanostructure arrays for plasmonic applications: annealed island films versus nanoimprint lithography

NASA Astrophysics Data System (ADS)

Lopatynskyi, Andrii M.; Lytvyn, Vitalii K.; Nazarenko, Volodymyr I.; Guo, L. Jay; Lucas, Brandon D.; Chegel, Volodymyr I.

2015-03-01

This paper attempts to compare the main features of random and highly ordered gold nanostructure arrays (NSA) prepared by thermally annealed island film and nanoimprint lithography (NIL) techniques, respectively. Each substrate possesses different morphology in terms of plasmonic enhancement. Both methods allow such important features as spectral tuning of plasmon resonance position depending on size and shape of nanostructures; however, the time and cost is quite different. The respective comparison was performed experimentally and theoretically for a number of samples with different geometrical parameters. Spectral characteristics of fabricated NSA exhibited an expressed plasmon peak in the range from 576 to 809 nm for thermally annealed samples and from 606 to 783 nm for samples prepared by NIL. Modelling of the optical response for nanostructures with typical shapes associated with these techniques (parallelepiped for NIL and semi-ellipsoid for annealed island films) was performed using finite-difference time-domain calculations. Mathematical simulations have indicated the dependence of electric field enhancement on the shape and size of the nanoparticles. As an important point, the distribution of electric field at so-called `hot spots' was considered. Parallelepiped-shaped nanoparticles were shown to yield maximal enhancement values by an order of magnitude greater than their semi-ellipsoid-shaped counterparts; however, both nanoparticle shapes have demonstrated comparable effective electrical field enhancement values. Optimized Au nanostructures with equivalent diameters ranging from 85 to 143 nm and height equal to 35 nm were obtained for both techniques, resulting in the largest electrical field enhancement. The application of island film thermal annealing method for nanochips fabrication can be considered as a possible cost-effective platform for various surface-enhanced spectroscopies; while the NIL-fabricated NSA looks like more effective for sensing of small-size objects.

Characterization of Ze and LDR of nonspherical and inhomogeneous ice particles for 95-GHz cloud radar: Its implication to microphysical retrievals

NASA Astrophysics Data System (ADS)

Sato, Kaori; Okamoto, Hajime

2006-11-01

Effect of density, shape, and orientation on radar reflectivity factor (Ze) and linear depolarization ratio (LDR) at 95 GHz are investigated by using the discrete dipole approximation (DDA) for ice cloud studies. We consider hexagonal plate, hollow hexagonal column, and hollow bullet rosette in horizontal (2-D) or three-dimensional (3-D) random orientation. We first validate a widely used method to take into account the density and shape effects by the combinational use of Mie theory with the Maxwell-Garnett mixing rule (the MG-Mie method). It is found that the MG-Mie method underestimates Ze and its applicability is limited to sizes smaller than 40 μm. On the basis of the DDA, it is possible to separately treat density, aspect ratio, orientation, and shape. Effect of density turns out to be minor. Orientation and shape are the major controlling factors for Ze especially at effective radius reff > 100 μm and LDR except for very large sizes where the effect of orientation in LDR diminishes. Comparison between the DDA results and the analytical solution for 3-D Rayleigh spheroids show that LDR in the small size range is characterized by the target boundary and aspect ratio. In the large size range, LDR reveals features of a single target element; for example, LDR of bullet rosette is similar to that of a single branch of the particle. Combinational use of Ze and LDR is effective in microphysics retrieval for LDR < -23 dB. For LDR > -23 dB, additional information such as Doppler velocity is required.

Humans preserve non-human primate pattern of climatic adaptation

NASA Astrophysics Data System (ADS)

Buck, Laura T.; De Groote, Isabelle; Hamada, Yuzuru; Stock, Jay T.

2018-07-01

There is evidence for early Pleistocene Homo in northern Europe, a novel hominin habitat. Adaptations enabling this colonisation are intriguing given suggestions that Homo exhibits physiological and behavioural malleability associated with a 'colonising niche'. Differences in body size/shape between conspecifics from different climates are well-known in mammals, could relatively flexible size/shape have been important to Homo adapting to cold habitats? If so, at what point did this evolutionary stragegy arise? To address these questions a base-line for adaptation to climate must be established by comparison with outgroups. We compare skeletons of Japanese macaques from four latitudes and find inter-group differences in postcranial and cranial size and shape. Very small body mass and cranial size in the Southern-most (island) population are most likely affected by insularity as well as ecogeographic scaling. Limb lengths and body breadths show group differences that accord with the expectations of thermoregulation across the whole range of latitudes. Postcranial size appears to vary more than shape, yet there is also evidence that limb segments follow Allen's rule in the forelimb at least, suggesting differing climatic signals in different regions of the skeleton. In contrast to other intraspecific studies of catarrhine ecogeography, the results presented here demonstrate non-allometric latitudinal patterns in craniofacial shape in Japanese macaques, which align closely with what is seen in cold-adapted humans. These insights begin to provide a comparison for hominin adaptation to similar habitat diversity and the role of biological adaptation in shaping the evolution and dispersal of Homo species.

Wing morphometrics of Aedes (Ochlerotatus) albifasciatus (Macquart, 1838) (Diptera: Culicidae) from different climatic regions of Argentina.

PubMed

Garzón, Maximiliano J; Schweigmann, Nicolás

2018-05-16

Gene flow restrictions between populations of Aedes albifasciatus, the vector of Western equine encephalitis and Dirophilaria immitis, have been described in the central region of Argentina. Genetic and eco-physiological variations usually result in local forms reflecting the climatic regions. Mosquito wings and their different parts have ecological functions in flight and communication. Therefore, wing shape could be considered an aspect of sexual dimorphism, and its eco-physiological responses can be expressed as morphological changes induced by the environment. To compare the geographical and sexual variations with respect to wing shape and size in two Ae. albifasciatus populations from contrasting climates of Argentina (temperate: Buenos Aires, and the arid steppe of Patagonia: Sarmiento), the wings of adults reared in thermal trays at different constant temperatures (10-29 °C) were analyzed. The wing size of Ae. albifasciatus showed inverse linear relationships with the rearing thermal condition and higher slope for Buenos Aires. In the cool range (10-17 °C), geographical size variations responded to the converse Bergmann's rule, where Buenos Aires individuals were larger than those from Sarmiento. Sexual shape dimorphism occurred in both populations while geographical variation in shape was observed in both sexes. Buenos Aires individuals showed greater response sensitivity with respect to the size-temperature relation than those from Sarmiento. The converse Bergmann's rule in size variation could be due to a higher development rate in Sarmiento to produce more cohorts in the limited favorable season. The shape could be more relevant with respect to the size in the study of population structures due to the size being more liable to vary due to changes in the environment. The geographical variations with respect to morphology could be favored by the isolation between populations and adaptations to the environmental conditions. Our results demonstrate that the shape and size of wing provide useful phenotypic information for studies related to sexual and environmental adaptations.

Evaluation of Elevation, Slope and Stream Network Quality of SPOT Dems

NASA Astrophysics Data System (ADS)

El Hage, M.; Simonetto, E.; Faour, G.; Polidori, L.

2012-07-01

Digital elevation models are considered the most useful data for dealing with geomorphology. The quality of these models is an important issue for users. This quality concerns position and shape. Vertical accuracy is the most assessed in many studies and shape quality is often neglected. However, both of them have an impact on the quality of the final results for a particular application. For instance, the elevation accuracy is required for orthorectification and the shape quality for geomorphology and hydrology. In this study, we deal with photogrammetric DEMs and show the importance of the quality assessment of both elevation and shape. For this purpose, we produce several SPOT HRV DEMs with the same dataset but with different template size, that is one of the production parameters from optical images. Then, we evaluate both elevation and shape quality. The shape quality is assessed with in situ measurements and analysis of slopes as an elementary shape and stream networks as a complex shape. We use the fractal dimension and sinuosity to evaluate the stream network shape. The results show that the elevation accuracy as well as the slope accuracy are affected by the template size. Indeed, an improvement of 1 m in the elevation accuracy and of 5 degrees in the slope accuracy has been obtained while changing this parameter. The elevation RMSE ranges from 7.6 to 8.6 m, which is smaller than the pixel size (10 m). For slope, the RMSE depends on the sampling distance. With a distance of 10 m, the minimum slope RMSE is 11.4 degrees. The stream networks extracted from these DEMs present a higher fractal dimension than the reference river. Moreover, the fractal dimension of the extracted networks has a negligible change according to the template size. Finally, the sinuosity of the stream networks is slightly affected by the change of the template size.

Micro Fluidic Channel Machining on Fused Silica Glass Using Powder Blasting

PubMed Central

Jang, Ho-Su; Cho, Myeong-Woo; Park, Dong-Sam

2008-01-01

In this study, micro fluid channels are machined on fused silica glass via powder blasting, a mechanical etching process, and the machining characteristics of the channels are experimentally evaluated. In the process, material removal is performed by the collision of micro abrasives injected by highly compressed air on to the target surface. This approach can be characterized as an integration of brittle mode machining based on micro crack propagation. Fused silica glass, a high purity synthetic amorphous silicon dioxide, is selected as a workpiece material. It has a very low thermal expansion coefficient and excellent optical qualities and exceptional transmittance over a wide spectral range, especially in the ultraviolet range. The powder blasting process parameters affecting the machined results are injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns. In this study, the influence of the number of nozzle scanning, abrasive particle size, and pattern size on the formation of micro channels is investigated. Machined shapes and surface roughness are measured using a 3-dimensional vision profiler and the results are discussed. PMID:27879730

When things go pear shaped: contour variations of contacts

NASA Astrophysics Data System (ADS)

Utzny, Clemens

2013-04-01

Traditional control of critical dimensions (CD) on photolithographic masks considers the CD average and a measure for the CD variation such as the CD range or the standard deviation. Also systematic CD deviations from the mean such as CD signatures are subject to the control. These measures are valid for mask quality verification as long as patterns across a mask exhibit only size variations and no shape variation. The issue of shape variations becomes especially important in the context of contact holes on EUV masks. For EUV masks the CD error budget is much smaller than for standard optical masks. This means that small deviations from the contact shape can impact EUV waver prints in the sense that contact shape deformations induce asymmetric bridging phenomena. In this paper we present a detailed study of contact shape variations based on regular product data. Two data sets are analyzed: 1) contacts of varying target size and 2) a regularly spaced field of contacts. Here, the methods of statistical shape analysis are used to analyze CD SEM generated contour data. We demonstrate that contacts on photolithographic masks do not only show size variations but exhibit also pronounced nontrivial shape variations. In our data sets we find pronounced shape variations which can be interpreted as asymmetrical shape squeezing and contact rounding. Thus we demonstrate the limitations of classic CD measures for describing the feature variations on masks. Furthermore we show how the methods of statistical shape analysis can be used for quantifying the contour variations thus paving the way to a new understanding of mask linearity and its specification.

Thermophysical modeling of main-belt asteroids from WISE thermal data

NASA Astrophysics Data System (ADS)

Hanuš, J.; Delbo', M.; Ďurech, J.; Alí-Lagoa, V.

2018-07-01

By means of a varied-shape thermophysical model of Hanuš et al. (2015) that takes into account asteroid shape and pole uncertainties, we analyze the thermal infrared data acquired by the NASA's Wide-field Infrared Survey Explorer of about 300 asteroids with derived convex shape models. We utilize publicly available convex shape models and rotation states as input for the thermophysical modeling. For more than one hundred asteroids, the thermophysical modeling gives us an acceptable fit to the thermal infrared data allowing us to report their thermophysical properties such as size, thermal inertia, surface roughness or visible geometric albedo. This work more than doubles the number of asteroids with determined thermophysical properties, especially the thermal inertia. In the remaining cases, the shape model and pole orientation uncertainties, specific rotation or thermophysical properties, poor thermal infrared data or their coverage prevent the determination of reliable thermophysical properties. Finally, we present the main results of the statistical study of derived thermophysical parameters within the whole population of main-belt asteroids and within few asteroid families. Our sizes based on TPM are, in average, consistent with the radiometric sizes reported by Mainzer et al. (2016). The thermal inertia increases with decreasing size, but a large range of thermal inertia values is observed within the similar size ranges between D ∼ 10-100 km. We derived unexpectedly low thermal inertias ( < 20 J m-2 s- 1 / 2 K-1) for several asteroids with sizes 10 < D < 50 km, indicating a very fine and mature regolith on these small bodies. The thermal inertia values seem to be consistent within several collisional families, however, the statistical sample is in all cases rather small. The fast rotators with rotation period P ≲ 4 h tend to have slightly larger thermal inertia values, so probably do not have a fine regolith on the surface. This could be explained, for example, by the loss of the fine regolith due to the centrifugal force, or by the ineffectiveness of the regolith production(e.g., by the thermal cracking mechanism of Delbo' et al. 2014).

Size- and Shape-Dependent Antibacterial Studies of Silver Nanoparticles Synthesized by Wet Chemical Routes

PubMed Central

Raza, Muhammad Akram; Kanwal, Zakia; Rauf, Anum; Sabri, Anjum Nasim; Riaz, Saira; Naseem, Shahzad

2016-01-01

Silver nanoparticles (AgNPs) of different shapes and sizes were prepared by solution-based chemical reduction routes. Silver nitrate was used as a precursor, tri-sodium citrate (TSC) and sodium borohydride as reducing agents, while polyvinylpyrrolidone (PVP) was used as a stabilizing agent. The morphology, size, and structural properties of obtained nanoparticles were characterized by scanning electron microscopy (SEM), UV-visible spectroscopy (UV-VIS), and X-ray diffraction (XRD) techniques. Spherical AgNPs, as depicted by SEM, were found to have diameters in the range of 15 to 90 nm while lengths of the edges of the triangular particles were about 150 nm. The characteristic surface plasmon resonance (SPR) peaks of different spherical silver colloids occurring in the wavelength range of 397 to 504 nm, whereas triangular particles showed two peaks, first at 392 nm and second at 789 nm as measured by UV-VIS. The XRD spectra of the prepared samples indicated the face-centered cubic crystalline structure of metallic AgNPs. The in vitro antibacterial properties of all synthesized AgNPs against two types of Gram-negative bacteria, Pseudomonas aeruginosa and Escherichia coli were examined by Kirby–Bauer disk diffusion susceptibility method. It was noticed that the smallest-sized spherical AgNPs demonstrated a better antibacterial activity against both bacterial strains as compared to the triangular and larger spherical shaped AgNPs. PMID:28335201

Thermal Intertias of Main-Belt Asteroids from Wise Thermal Infrared Data

NASA Astrophysics Data System (ADS)

Hanus, Josef; Delbo', Marco; Durech, Josef; Alí-Lagoa, Victor

2014-11-01

By means of a modified thermophysical model (TPM) that takes into account asteroid shape and pole uncertainties, we analyze the thermal infrared data acquired by the NASA's Wide-field Infrared Survey Explorer (WISE) of about 300 asteroids with derived convex shape models. We adopt convex shape models from the DAMIT database (Durech et al., 2010, A&A 513, A46) and present new determinations based on optical disk-integrated photometry and the lightcurve inversion method (Kaasalainen & Torppa, 2001, Icarus 153, 37). This work more than double the number of asteroids with determined thermophysical properties. We also discuss cases in which shape uncertainties prevent the determination of reliable thermophysical properties. This is per-se a novel result, as the effect of shape has been often neglected in thermophysical modeling of asteroids.We also present the main results of the statistical study of derived thermophysical parameters within the whole population of MBAs and within few asteroid families. The thermal inertia increases with decreasing size, but a large range of thermal inertia values is observed within the similar size ranges between 10-100 km. Surprisingly, we derive low (<20J m^{-2} s^{-1/2} K^{-1}) thermal inertia values for several asteroids with sizes D>10 km, indicating a very fine and mature regolith on these small bodies. The work of JH and MD was carried under the contract 11-BS56-008 (SHOCKS) of the French Agence National de la Recherche (ANR), and JD has been supported by the grant GACR P209/10/0537 of the Czech Science Foundation.

Dose calculation for electron therapy using an improved LBR method.

PubMed

Gebreamlak, Wondesen T; Tedeschi, David J; Alkhatib, Hassaan A

2013-07-01

To calculate the percentage depth dose (PDD) of any irregularly shaped electron beam using a modified lateral build-up ratio (LBR) method. Percentage depth dose curves were measured using 6, 9, 12, and 15 MeV electron beam energies for applicator cone sizes of 6 × 6, 10 × 10, 14 × 14, and 20 × 20 cm(2). Circular cutouts for each cone were prepared from 2.0 cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The LBR for each circular cutout was calculated from the measured PDD curve using the open field of the 14 × 14 cm(2) cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter [σR(z)] of the electron shower was calculated. Unlike the commonly accepted assumption that σR(z) is independent of cutout size, it is shown that its value increases linearly with circular cutout size (R). Using this characteristic of the lateral spread parameter, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves. In this research, it is shown that the lateral spread parameter σR(z) increases with cutout size. For radii of circular cutout sizes up to the equilibrium range of the electron beam, the increase of σR(z) with the cutout size is linear. The percentage difference of the calculated PDD curve from the measured PDD data for irregularly shaped cutouts was under 1.0% in the region between the surface and therapeutic range of the electron beam. Similar results were obtained for four electron beam energies (6, 9, 12, and 15 MeV).

TWO-PHASE FORMATION IN SOLUTIONS OF TOBACCO MOSAIC VIRUS AND THE PROBLEM OF LONG-RANGE FORCES

PubMed Central

Oster, Gerald

1950-01-01

In a nearly salt-free medium, a dilute tobacco mosaic virus solution of rod-shaped virus particles of uniform length forms two phases; the bottom optically anisotropic phase has a greater virus concentration than has the top optically isotropic phase. For a sample containing particles of various lengths, the bottom phase contains longer particles than does the top and the concentrations top and bottom are nearly equal. The longer the particles the less the minimum concentration necessary for two-phase formation. Increasing the salt concentration increases the minimum concentration. The formation of two phases is explained in terms of geometrical considerations without recourse to the concept of long-range attractive forces. The minimum concentration for two-phase formation is that concentration at which correlation in orientation between the rod-shaped particles begins to take place. This concentration is determined by the thermodynamically effective size and shape of the particles as obtained from the concentration dependence of the osmotic pressure of the solutions measured by light scattering. The effective volume of the particles is introduced into the theory of Onsager for correlation of orientation of uniform size rods and good agreement with experiment is obtained. The theory is extended to a mixture of non-uniform size rods and to the case in which the salt concentration is varied, and agreement with experiment is obtained. The thermodynamically effective volume of the particles and its dependence on salt concentration are explained in terms of the shape of the particles and the electrostatic repulsion between them. Current theories of the hydration of proteins and of long-range forces are critically discussed. The bottom layer of freshly purified tobacco mosaic virus samples shows Bragg diffraction of visible light. The diffraction data indicate that the virus particles in solution form three-dimensional crystals approximately the size of crystalline inclusion bodies found in the cells of plants suffering from the disease. PMID:15422102

Development of a Searchable Database of Cryoablation Simulations for Use in Treatment Planning.

PubMed

Boas, F Edward; Srimathveeravalli, Govindarajan; Durack, Jeremy C; Kaye, Elena A; Erinjeri, Joseph P; Ziv, Etay; Maybody, Majid; Yarmohammadi, Hooman; Solomon, Stephen B

2017-05-01

To create and validate a planning tool for multiple-probe cryoablation, using simulations of ice ball size and shape for various ablation probe configurations, ablation times, and types of tissue ablated. Ice ball size and shape was simulated using the Pennes bioheat equation. Five thousand six hundred and seventy different cryoablation procedures were simulated, using 1-6 cryoablation probes and 1-2 cm spacing between probes. The resulting ice ball was measured along three perpendicular axes and recorded in a database. Simulated ice ball sizes were compared to gel experiments (26 measurements) and clinical cryoablation cases (42 measurements). The clinical cryoablation measurements were obtained from a HIPAA-compliant retrospective review of kidney and liver cryoablation procedures between January 2015 and February 2016. Finally, we created a web-based cryoablation planning tool, which uses the cryoablation simulation database to look up the probe spacing and ablation time that produces the desired ice ball shape and dimensions. Average absolute error between the simulated and experimentally measured ice balls was 1 mm in gel experiments and 4 mm in clinical cryoablation cases. The simulations accurately predicted the degree of synergy in multiple-probe ablations. The cryoablation simulation database covers a wide range of ice ball sizes and shapes up to 9.8 cm. Cryoablation simulations accurately predict the ice ball size in multiple-probe ablations. The cryoablation database can be used to plan ablation procedures: given the desired ice ball size and shape, it will find the number and type of probes, probe configuration and spacing, and ablation time required.

An analysis of beak shape variation in two ages of domestic turkeys (Meleagris gallopavo) using landmark-based geometric morphometrics.

PubMed

Dalton, Hillary A; Wood, Benjamin J; Widowski, Tina M; Guerin, Michele T; Torrey, Stephanie

2017-01-01

The objective of this study was to assess beak shape variation in domestic turkeys (Meleagris gallopavo) and determine the effects of age, sex, and beak size on beak shape variation using geometric morphometrics. Dorsal and right lateral images were taken of 2442 turkeys at 6 and 18.5 weeks of age. Landmarks were digitized in tpsDig in three analyses of the dorsal upper mandible, lateral upper mandible, and lateral lower mandible shape of each turkey at both ages. The coordinate data were then subjected to a principal components analysis (PCA), multivariate regression, and a canonical variates analysis (CVA) with a Procrustes ANOVA in MorphoJ. For the dorsal images, three principal components (PCs) showed beak shape variation ranged from long, narrow, and pointed to short, wide, and blunt upper mandibles at both ages (6 weeks: 95.36%, 18.5 weeks: 92.21%). Three PCs showed the lateral upper mandible shape variation ranged from long, wide beaks with long, curved beak tips to short, narrow beaks with short, pointed beak tips at both ages (6 weeks: 94.91%, 18.5 weeks: 94.33%). Three PCs also explained 97.80% (6 weeks) and 97.11% (18.5 weeks) of the lateral lower mandible shape variation ranging from wide and round to narrow and thin lower mandibles with superior/inferior beak tip shifts. Beak size accounted for varying proportions of the beak shape variation (0.96-54.76%; P < 0.0001) in the three analyses of each age group. For all the analyses, the CVA showed sexual dimorphism in beak shape (P < 0.0001) with female upper mandibles appearing wider and blunter dorsally with long, curved beak tips laterally. Whereas male turkey upper mandibles had a narrow, pointed dorsal appearance and short, pointed beak tips laterally. Future applications of beak shape variability could have a genetic and welfare value by incorporating beak shape variation to select for specific turkey beak phenotypes as an alternative to beak treatment.

An analysis of beak shape variation in two ages of domestic turkeys (Meleagris gallopavo) using landmark-based geometric morphometrics

PubMed Central

Widowski, Tina M.; Guerin, Michele T.

2017-01-01

The objective of this study was to assess beak shape variation in domestic turkeys (Meleagris gallopavo) and determine the effects of age, sex, and beak size on beak shape variation using geometric morphometrics. Dorsal and right lateral images were taken of 2442 turkeys at 6 and 18.5 weeks of age. Landmarks were digitized in tpsDig in three analyses of the dorsal upper mandible, lateral upper mandible, and lateral lower mandible shape of each turkey at both ages. The coordinate data were then subjected to a principal components analysis (PCA), multivariate regression, and a canonical variates analysis (CVA) with a Procrustes ANOVA in MorphoJ. For the dorsal images, three principal components (PCs) showed beak shape variation ranged from long, narrow, and pointed to short, wide, and blunt upper mandibles at both ages (6 weeks: 95.36%, 18.5 weeks: 92.21%). Three PCs showed the lateral upper mandible shape variation ranged from long, wide beaks with long, curved beak tips to short, narrow beaks with short, pointed beak tips at both ages (6 weeks: 94.91%, 18.5 weeks: 94.33%). Three PCs also explained 97.80% (6 weeks) and 97.11% (18.5 weeks) of the lateral lower mandible shape variation ranging from wide and round to narrow and thin lower mandibles with superior/inferior beak tip shifts. Beak size accounted for varying proportions of the beak shape variation (0.96–54.76%; P < 0.0001) in the three analyses of each age group. For all the analyses, the CVA showed sexual dimorphism in beak shape (P < 0.0001) with female upper mandibles appearing wider and blunter dorsally with long, curved beak tips laterally. Whereas male turkey upper mandibles had a narrow, pointed dorsal appearance and short, pointed beak tips laterally. Future applications of beak shape variability could have a genetic and welfare value by incorporating beak shape variation to select for specific turkey beak phenotypes as an alternative to beak treatment. PMID:28934330

Thermal modeling of cogging process using finite element method

NASA Astrophysics Data System (ADS)

Khaled, Mahmoud; Ramadan, Mohamad; Fourment, Lionel

2016-10-01

Among forging processes, incremental processes are those where the work piece undergoes several thermal and deformation steps with small increment of deformation. They offer high flexibility in terms of the work piece size since they allow shaping wide range of parts from small to large size. Since thermal treatment is essential to obtain the required shape and quality, this paper presents the thermal modeling of incremental processes. The finite element discretization, spatial and temporal, is exposed. Simulation is performed using commercial software Forge 3. Results show the thermal behavior at the beginning and at the end of the process.

Optimization of physiological properties of hydroxyapatite as a vaccine adjuvant.

PubMed

Hayashi, Masayuki; Aoshi, Taiki; Kogai, Yasumichi; Nomi, Daisuke; Haseda, Yasunari; Kuroda, Etsushi; Kobiyama, Kouji; Ishii, Ken J

2016-01-12

Various particles such as Alum or silica are known to act as an adjuvant if co-administered with vaccine antigens. Several reports have demonstrated that the adjuvanticity is strongly affected by the physicochemical properties of particles such as the size, shape and surface charge, although the required properties and its relationship to the adjuvanticity are still controversial. Hydroxyapatite particle (HAp) composed of calcium phosphate has been shown to work as adjuvant in mice. However, the properties of HAp required for the adjuvanticity have not been fully characterized yet. In this study, we examined the role of size or shape of HAps in the antibody responses after immunization with antigen. HAps whose diameter ranging between 100 and 400 nm provided significantly higher antibody responses than smaller or larger ones. By comparison between sphere and rod shaped HAps, rod shaped HAps induced stronger inflammasome-dependent IL-1β production than the sphere shaped ones in vitro. However, sphere- and rod-shaped HAp elicited comparable antibody response in WT mice. Vice versa, Nlrp3(-/-), Asc(-/-) or Caspase1(-/-) mice provided comparable level of antibody responses to HAp adjuvanted vaccination. Collectively, our results demonstrated that the size rather than shape is a more critical property, and IL-1β production via NLRP3 inflammasome is dispensable for the adjuvanticity of HAps in mice. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effects of particle shape, size, and interaction on colloidal glasses and gels

NASA Astrophysics Data System (ADS)

Kramb, Ryan C.

Using multiple step seeded emulsion polymerization reactions, colloid particles of tunable shape are synthesized from polystyrene. In all, four particle shapes are studied referred to as spheres (S), heteronuclear dicolloids (hDC), symmetric homonuclear dicolloids (sDC), and tricolloids (TC). Two size ranges of particles are studied with approximate diameters in the range of 200-300nm and 1.1-1.3mum. The solvent ionic strength is varied from 10 -3M to 1M resulting in particle interaction potentials that range from repulsive to attractive. The effect of anisotropic shape is found to increase the glass transition volume fraction (φg) in good agreement with activated naive Mode Coupling Theory (nMCT) calculations. Differences in φg and the linear elastic modulus (G0') due to particle shape can be understood in terms of the Random Close Packed volume fraction (φRCP ) for each shape; φRCP- φg is a constant. In addition, a reentrant phase diagram is found for S and sDC particles with a maximum in the fluid state volume fraction found at weakly attractive interaction potential, in agreement well with theoretical calculations. Nonlinear rheology and yielding behavior of repulsive and attractive spheres and anisotropic particles are examined and understood in terms of barriers constraining motion. The barriers are due to interparticle bonds or cages constraining translational or rotational motion. Yield stress has similar volume fraction dependence as G 0' and a similar framework is used to understand differences due to particle shape and interaction. For larger particles, the effects of shape and interaction are studied with respect to dynamic yielding and shear thickening. The dynamic yield stress is found to increase with volume fraction while the stress at thickening is constant. The intersection of these indicates a possible jamming point below φRCP.

Fabrication of Polyhedral Particles from Spherical Colloids and Their Self-Assembly into Rotator Phases**

PubMed Central

Vutukuri, Hanumantha Rao; Imhof, Arnout; van Blaaderen, Alfons

2014-01-01

Particle shape is a critical parameter that plays an important role in self-assembly, for example, in designing targeted complex structures with desired properties. Over the last decades, an unprecedented range of monodisperse nanoparticle systems with control over the shape of the particles have become available. In contrast, the choice of micrometer-sized colloidal building blocks of particles with flat facets, that is, particles with polygonal shapes, is significantly more limited. This can be attributed to the fact that in contrast to nanoparticles, the larger colloids are significantly harder to synthesize as single crystals. It is now shown that a very simple building block, such as a micrometer-sized polymeric spherical colloidal particle, is already enough to fabricate particles with regularly placed flat facets, including completely polygonal shapes with sharp edges. As an illustration that the yields are high enough for further self-assembly studies, the formation of three-dimensional rotator phases of fluorescently labelled, micrometer-sized, and charged rhombic dodecahedron particles was demonstrated. This method for fabricating polyhedral particles opens a new avenue for designing new materials. PMID:25366869

Determining Size Distribution at the Phoenix Landing Site

NASA Astrophysics Data System (ADS)

Mason, E. L.; Lemmon, M. T.

2016-12-01

Dust aerosols play a crucial role in determining atmospheric radiative heating on Mars through absorption and scattering of sunlight. How dust scatters and absorbs light is dependent on size, shape, composition, and quantity. Optical properties of the dust have been well constrained in the visible and near infrared wavelengths using various methods [Wolff et al. 2009, Lemmon et al. 2004]. In addition, the dust is nonspherical, and irregular shapes have shown to work well in determining effective particle size [Pollack et al. 1977]. Variance of the size distribution is less constrained but constitutes an important parameter in fully describing the dust. The Phoenix Lander's Surface Stereo Imager performed several cross-sky brightness surveys to determine the size distribution and scattering properties of dust in the wavelength range of 400 to 1000 nm. In combination with a single-layer radiative transfer model, these surveys can be used to help constrain variance of the size distribution. We will present a discussion of seasonal size distribution as it pertains to the Phoenix landing site.

An assessment technique for computer-socket manufacturing

PubMed Central

Sanders, Joan; Severance, Michael

2015-01-01

An assessment strategy is presented for testing the quality of carving and forming of individual computer aided manufacturing facilities. The strategy is potentially useful to facilities making sockets and companies marketing manufacturing equipment. To execute the strategy, an evaluator fabricates a collection of test models and sockets using the manufacturing suite under evaluation, and then measures their shapes using scanning equipment. Overall socket quality is assessed by comparing socket shapes with electronic file shapes. Then model shapes are compared with electronic file shapes to characterize carving performance. Socket shapes are compared with model shapes to characterize forming performance. The mean radial error (MRE), which is the average difference in radii between the two shapes being compared, provides insight into sizing quality. Inter-quartile range (IQR), the range of radial error for the best matched half of the points on the surfaces being compared, provides insight into shape quality. By determining MRE and IQR for carving and forming separately, the source(s) of socket shape error may be pinpointed. The developed strategy may provide a useful tool to the prosthetics community and industry to help identify problems and limitations in computer aided manufacturing and insight into appropriate modifications to overcome them. PMID:21938663

16 CFR 1203.4 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... solid model in the shape of a human head of sizes A, E, J, M, and O as defined in draft ISO/DIS 6220... configure the helmet for a range of different head sizes. (d) Coronal plane is an anatomical plane... to secure its position on the headform. The mass of the preload ballast is 5 kg (11 lb). (j...

16 CFR 1203.4 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... solid model in the shape of a human head of sizes A, E, J, M, and O as defined in draft ISO/DIS 6220... configure the helmet for a range of different head sizes. (d) Coronal plane is an anatomical plane... to secure its position on the headform. The mass of the preload ballast is 5 kg (11 lb). (j...

Home range size of Tengmalm's owl during breeding in Central Europe is determined by prey abundance.

PubMed

Kouba, Marek; Bartoš, Luděk; Tomášek, Václav; Popelková, Alena; Šťastný, Karel; Zárybnická, Markéta

2017-01-01

Animal home ranges typically characterized by their size, shape and a given time interval can be affected by many different biotic and abiotic factors. However, despite the fact that many studies have addressed home ranges, our knowledge of the factors influencing the size of area occupied by different animals is, in many cases, still quite poor, especially among raptors. Using radio-telemetry (VHF; 2.1 g tail-mounted tags) we studied movements of 20 Tengmalm's owl (Aegolius funereus) males during the breeding season in a mountain area of Central Europe (the Czech Republic, the Ore Mountains: 50° 40' N, 13° 35' E) between years 2006-2010, determined their average hunting home range size and explored what factors affected the size of home range utilised. The mean breeding home range size calculated according to 95% fixed kernel density estimator was 190.7 ± 65.7 ha (± SD) with a median value of 187.1 ha. Home range size was affected by prey abundance, presence or absence of polygyny, the number of fledglings, and weather conditions. Home range size increased with decreasing prey abundance. Polygynously mated males had overall larger home range than those mated monogamously, and individuals with more fledged young possessed larger home range compared to those with fewer raised fledglings. Finally, we found that home ranges recorded during harsh weather (nights with strong wind speed and/or heavy rain) were smaller in size than those registered during better weather. Overall, the results provide novel insights into what factors may influence home range size and emphasize the prey abundance as a key factor for breeding dynamics in Tengmalm's owl.

Three-dimensional (3D) geometric morphometric analysis of human premolars to assess sexual dimorphism and biological ancestry in Australian populations.

PubMed

Yong, Robin; Ranjitkar, Sarbin; Lekkas, Dimitra; Halazonetis, Demetrios; Evans, Alistair; Brook, Alan; Townsend, Grant

2018-06-01

This study aimed to investigate size and shape variation of human premolars between Indigenous Australians and Australians of European ancestry, and to assess whether sex and ancestry could be differentiated between these groups using 3D geometric morphometrics. Seventy dental casts from each group, equally subdivided by sex, were scanned using a structured-light scanner. The 3D meshes of upper and lower premolars were processed using geometric morphometric methods. Seventy-two landmarks were recorded for upper premolars and 50 landmarks for lower premolars. For each tooth type, two-way ANOVA was used to assess group differences in centroid size. Shape variations were explored using principal component analysis and visualized using 3D morphing. Two-way Procrustes ANOVA was applied to test group differences for ancestry and sex, and a "leave-one-out" discriminant function was applied to assess group assignment. Centroid size and shape did not display significant difference between the sexes. Centroid size was larger in Indigenous Australians for upper premolars and lower second premolars compared to the Australians of European ancestry. Significant shape variation was noted between the two ancestral groups for upper premolars and the lower first premolar. Correct group assignment of individual teeth to their ancestral groups ranged between 80.0 and 92.8% for upper premolars and 60.0 and 75.7% for lower premolars. Our findings provide evidence of significant size and shape variation in human premolars between the two ancestral groups. High classification rates based on shape analysis of upper premolars highlight potential application of geometric morphometrics in anthropological, bioarcheological and forensic contexts. © 2018 Wiley Periodicals, Inc.

Grain size distribution and microstructures of experimentally sheared granitoid gouge at coseismic slip rates - Criteria to distinguish seismic and aseismic faults?

NASA Astrophysics Data System (ADS)

Stünitz, Holger; Keulen, Nynke; Hirose, Takehiro; Heilbronner, Renée

2010-01-01

Microstructures and grain size distribution from high velocity friction experiments are compared with those of slow deformation experiments of Keulen et al. (2007, 2008) for the same material (Verzasca granitoid). The mechanical behavior of granitoid gouge in fast velocity friction experiments at slip rates of 0.65 and 1.28 m/s and normal stresses of 0.4-0.9 MPa is characterized by slip weakening in a typical exponential friction coefficient vs displacement relationship. The grain size distributions yield similar D-values (slope of frequency versus grain size curve = 2.2-2.3) as those of slow deformation experiments (D = 2.0-2.3) for grain sizes larger than 1 μm. These values are independent of the total displacement above a shear strain of about γ = 20. The D-values are also independent of the displacement rates in the range of ˜1 μm/s to ˜1.3 m/s and do not vary in the normal stress range between 0.5 MPa and 500 MPa. With increasing displacement, grain shapes evolve towards more rounded and less serrated grains. While the grain size distribution remains constant, the progressive grain shape evolution suggests that grain comminution takes place by attrition at clast boundaries. Attrition produces a range of very small grain sizes by crushing with a D <-value = 1. The results of the study demonstrate that most cataclastic and gouge fault zones may have resulted from seismic deformation but the distinction of seismic and aseismic deformation cannot be made on the basis of grain size distribution.

Influence of size and shape of sub-micrometer light scattering centers in ZnO-assisted TiO2 photoanode for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Pham, Trang T. T.; Mathews, Nripan; Lam, Yeng-Ming; Mhaisalkar, Subodh

2018-03-01

Sub-micrometer cavities have been incorporated in the TiO2 photoanode of dye-sensitized solar cell to enhance its optical property with light scattering effect. These are large pores of several hundred nanometers in size and scatter incident light due to the difference refraction index between the scattering center and the surrounding materials, according to Mie theory. The pores are created using polystyrene (PS) or zinc oxide (ZnO) templates reported previously which resulted in ellipsoidal and spherical shapes, respectively. The effect of size and shape of scattering center was modeled using a numerical analysis finite-difference time-domain (FDTD). The scattering cross-section was not affected significantly with different shapes if the total displacement volume of the scattering center is comparable. Experiments were carried out to evaluate the optical property with varying size of ZnO templates. Photovoltaic effect of dye-sensitized solar cells made from these ZnO-assisted films were investigated with incident-photon-to-current efficiency to understand the effect of scattering center size on the enhancement of absorption. With 380 nm macropores incorporated, the power conversion efficiency has increased by 11% mostly thanks to the improved current density, while 170 nm and 500 nm macropores samples did not have increment in sufficiently wide range of absorbing wavelengths.

Characterization of dust from blast furnace cast house de-dusting.

PubMed

Lanzerstorfer, Christof

2017-10-01

During casting of liquid iron and slag, a considerable amount of dust is emitted into the cast house of a blast furnace (BF). Usually, this dust is extracted via exhaust hoods and subsequently separated from the ventilation air. In most BFs the cast house dust is recycled. In this study a sample of cast house dust was split by air classification into five size fractions, which were then analysed. Micrographs showed that the dominating particle type in all size fractions is that of single spherical-shaped particles. However, some irregular-shaped particles were also found and in the finest size fraction also some agglomerates were present. Almost spherical particles consisted of Fe and O, while highly irregular-shaped particles consisted of C. The most abundant element was Fe, followed by Ca and C. These elements were distributed relatively uniformly in the size fractions. As, Cd, Cu, K, Pb, S, Sb and Zn were enriched significantly in the fine size fractions. Thus, air classification would be an effective method for improved recycling. By separating a small fraction of fines (about 10-20%), a reduction of the mass of Zn in the coarse dust recycled in the range of 40-55% would be possible.

Development of a Searchable Database of Cryoablation Simulations for Use in Treatment Planning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boas, F. Edward, E-mail: boasf@mskcc.org; Srimathveeravalli, Govindarajan, E-mail: srimaths@mskcc.org; Durack, Jeremy C., E-mail: durackj@mskcc.org

PurposeTo create and validate a planning tool for multiple-probe cryoablation, using simulations of ice ball size and shape for various ablation probe configurations, ablation times, and types of tissue ablated.Materials and MethodsIce ball size and shape was simulated using the Pennes bioheat equation. Five thousand six hundred and seventy different cryoablation procedures were simulated, using 1–6 cryoablation probes and 1–2 cm spacing between probes. The resulting ice ball was measured along three perpendicular axes and recorded in a database. Simulated ice ball sizes were compared to gel experiments (26 measurements) and clinical cryoablation cases (42 measurements). The clinical cryoablation measurements weremore » obtained from a HIPAA-compliant retrospective review of kidney and liver cryoablation procedures between January 2015 and February 2016. Finally, we created a web-based cryoablation planning tool, which uses the cryoablation simulation database to look up the probe spacing and ablation time that produces the desired ice ball shape and dimensions.ResultsAverage absolute error between the simulated and experimentally measured ice balls was 1 mm in gel experiments and 4 mm in clinical cryoablation cases. The simulations accurately predicted the degree of synergy in multiple-probe ablations. The cryoablation simulation database covers a wide range of ice ball sizes and shapes up to 9.8 cm.ConclusionCryoablation simulations accurately predict the ice ball size in multiple-probe ablations. The cryoablation database can be used to plan ablation procedures: given the desired ice ball size and shape, it will find the number and type of probes, probe configuration and spacing, and ablation time required.« less

Separation of both fibrous and globular proteins on the basis of molecular weight using high-performance size exclusion chromatography.

PubMed

Barden, J A

1983-11-01

A high-performance size exclusion liquid chromatographic system has been used to separate proteins with different shapes solely on the basis of their molecular weights. After the effects of ionic and hydrophobic interactions with the stationary phase have been overcome, protein elution is normally governed by their effective size in solution. Conditions are described under which proteins, with isoelectric points within the normal operating pH range of the columns, are eluted independent of their Stokes' radii. Even fibrous proteins with axial ratios of 50 elute according to their known molecular weights over the range 2000-2,000,000.

Mix of Particles in 'Uchben' Close-up

NASA Technical Reports Server (NTRS)

2004-01-01

[figure removed for brevity, see original site] Figure 1

Close-up examination of a freshly exposed area of a rock called 'Uchben' in the 'Columbia Hills' of Mars reveals an assortment of particle shapes and sizes in the rock's makeup. NASA's Mars Exploration Rover Spirit used its microscopic imager during the rover's 286th martian day (Oct. 22, 2004) to take the frames assembled into this view. The view covers a circular hole ground into a target spot called 'Koolik' on Uchben by the rover's rock abrasion tool. The circle is 4.5 centimeters (1.8 inches) in diameter. Particles in the rock vary in shape from angular to round, and range in size from about 0.5 millimeter (0.2 inch) to too small to be seen. This assortment suggests that the rock originated from particles that had not been transported much by wind or water, because such a transport process would likely have resulted in more sorting of the particles by size and shape.

Colloid Science of Metal Nanoparticle Catalysts in 2D and 3D Structures. Challenges of Nucleation, Growth, Composition, Particle Shape, Size Control and their Influence on Activity and Selectivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Somorjai, Gabor A.; Park, Jeong Y.

2008-02-13

Recent breakthroughs in synthesis in nanosciences have achieved control of size and shapes of nanoparticles that are relevant for catalyst design. In this article, we review the advance of synthesis of nanoparticles, fabrication of two and three dimensional model catalyst system, characterization, and studies of activity and selectivity. The ability to synthesize monodispersed platinum and rhodium nanoparticles in the 1-10 nm range permitted us to study the influence of composition, structure, and dynamic properties of monodispersed metal nanoparticle on chemical reactivity and selectivity. We review the importance of size and shape of nanoparticles to determine the reaction selectivity in multi-pathmore » reactions. The influence of metal-support interaction has been studied by probing the hot electron flows through the metal-oxide interface in catalytic nanodiodes. Novel designs of nanoparticle catalytic systems are discussed.« less

Mix of Particles in "Uchben" Close-up

NASA Image and Video Library

2004-11-04

Close-up examination of a freshly exposed area of a rock called "Uchben" in the "Columbia Hills" of Mars reveals an assortment of particle shapes and sizes in the rock's makeup. NASA's Mars Exploration Rover Spirit used its microscopic imager during the rover's 286th martian day (Oct. 22, 2004) to take the frames assembled into this view. The view covers a circular hole ground into a target spot called "Koolik" on Uchben by the rover's rock abrasion tool. The circle is 4.5 centimeters (1.8 inches) in diameter. Particles in the rock vary in shape from angular to round, and range in size from about 0.5 millimeter (0.2 inch) to too small to be seen. This assortment suggests that the rock originated from particles that had not been transported much by wind or water, because such a transport process would likely have resulted in more sorting of the particles by size and shape. http://photojournal.jpl.nasa.gov/catalog/PIA07023

Fabrication and characterization of a nanometer-sized optical fiber electrode based on selective chemical etching for scanning electrochemical/optical microscopy.

PubMed

Maruyama, Kenichi; Ohkawa, Hiroyuki; Ogawa, Sho; Ueda, Akio; Niwa, Osamu; Suzuki, Koji

2006-03-15

We have already reported a method for fabricating ultramicroelectrodes (Suzuki, K. JP Patent, 2004-45394, 2004). This method is based on the selective chemical etching of optical fibers. In this work, we undertake a detailed investigation involving a combination of etched optical fibers with various types of tapered tip (protruding-shape, double- (or pencil-) shape and triple-tapered electrode) and insulation with electrophoretic paint. Our goal is to establish a method for fabricating nanometer-sized optical fiber electrodes with high reproducibility. As a result, we realized pencil-shaped and triple-tapered electrodes that had radii in the nanometer range with high reproducibility. These nanometer-sized electrodes showed well-defined sigmoidal curves and stable diffusion-limited responses with cyclic voltammetry. The pencil-shaped optical fiber, which has a conical tip with a cone angle of 20 degrees , was effective for controlling the electrode radius. The pencil-shaped electrodes had higher reproducibility and smaller electrode radii (r(app) < 1.0 nm) than those of other etched optical fiber electrodes. By using a pencil-shaped electrode with a 105-nm radius as a probe, we obtained simultaneous electrochemical and optical images of an implantable interdigitated array electrode. We achieved nanometer-scale resolution with a combination of scanning electrochemical microscopy SECM and optical microscopy. The resolution of the electrochemical and optical images indicated sizes of 300 and 930 nm, respectively. The neurites of living PC12 cells were also successfully imaged on a 1.6-microm scale by using the negative feedback mode of an SECM.

Pediatric Anthropometry

NASA Astrophysics Data System (ADS)

Klinich, Kathleen D.; Reed, Matthew P.

Anthropometry is the measurement of human size, shape, and physical capabilities. Most pediatric anthropometry data are gathered to describe child growth patterns, but data on body size, mass distribution, range of motion, and posture are used to develop crash test dummies and computational models of child occupants. Pediatric anthropometry data are also used to determine child restraint dimensions, so they will accommodate the applicable population of child occupants.

Does the long-range transport of African mineral dust across the Atlantic enhance their hygroscopicity?

NASA Astrophysics Data System (ADS)

Denjean, Cyrielle; Caquineau, Sandrine; Desboeufs, Karine; Laurent, Benoit; Quiñones Rosado, Mariana; Vallejo, Pamela; Mayol-Bracero, Olga; Formenti, Paola

2015-04-01

Influence of mineral dust on radiation balance is largely dependent on their ability to interact with water. While fresh mineral dusts are highly hydrophobic, various transformation processes (coagulation, heterogeneous chemical reaction) can modify the dust physical and chemical properties during long-range transport, which, in turn, can change the dust hygroscopic properties. The model predictions of the radiative effect by mineral dust still suffer of the lack of certainty of dust hygroscopic properties, and their temporal evolution during long-range transport. We present the first direct surface measurements of the hygroscopicity of Saharan dust after long-range transport over the Atlantic Ocean, their relationship with chemical composition, their influence on particle size and shape and implications for optical properties. Particles were collected during the DUST Aging and TransporT from Africa to the Caribbean (Dust-AttaCk) campaign at the Cape San Juan Puerto Rico station in June-July 2012. Environmental scanning electron microscopy (ESEM) was used to analyze the size, shape, chemical composition and hygroscopic properties of individual particles. At different levels of concentrations in summertime, the coarse mode of atmospheric aerosols in Puerto Rico is dominated by Saharan mineral dust. Most of aged dust particles survived atmospheric transport intact with no observed internal mixture with other species and did not show hygroscopic growth up to 94% relative humidity. This is certainly due to the fact that in summertime dust is mostly transported above the marine boundary layer. A minor portion of mineral dust (approximately 19-28% by number) were involved in atmospheric heterogeneous reactions with acidic gases (likely SO2 and HCl) and sea salt aggregation. While sulfate- and chloride-coated dust remained extremely hydrophobic, dust particles in internal mixing with NaCl underwent profound changes in their hygroscopicity, therefore in size and shape. We show that this change in particles size has important implications for their ability to scatter and absorb light. This behavior is also important for cloud properties since the increase of particles size reduces the supersaturating required for cloud droplet activation.

Synthesis and characterization of Fe-based metal and oxide based nanoparticles: discoveries and research highlights of potential applications in biology and medicine.

PubMed

Long, Nguyen Viet; Thi, Cao Minh; Yong, Yang; Cao, Yanqin; Wu, Haibo; Nogami, Masayuki

2014-01-01

In this review, we have presented the controlled synthesis of Fe-based metal and oxide nanoparticles with large size by chemical methods. The issues of the size, shape and morphology of Fe nanoparticles are discussed in the certain ranges of practical applications in biology and medicine. The homogeneous nanosystems of Fe-based metal and oxide nanoparticles with various sizes and shapes from the nano-to-micro ranges can be used in order to meet the demands of the treatments of dangerous tumors and cancers through magnetic hyperthermia and magnetic resonance imaging (MRI). In this context, the polyhedral Fe-based metal and oxide nanoparticles having large size in the ranges from 1000 nm to 5000 nm can be potentially used in magnetic hyperthermia and MRI in the innovative drug delivery, diagnosis, treatment, and therapy of tumor and cancer diseases because of their very high bio-adaptability. We have suggested that high stability and durability of Fe-based metal and oxide nanoparticles are very crucial to recent magnetic hyperthermia and MRI technology. The roles of various Fe-based nanostructures are focused in biomedical applications of tumors and cancers diagnostics, targeted drug delivery, and magnetic hyperthermia. Finally, Fe-based, α-, β- and γ-Fe2O3, and Fe3O4-based nanoparticles are shortly discussed in various potential applications in catalysis, biology, and medicine.

CHARACTERISTICS OF THERMOLUMINESCENCE LiF:Mg,Cu,Ag NANOPHOSPHOR.

PubMed

Yahyaabadi, A; Torkzadeh, F; Rezaei-Ochbelagh, D

2018-04-23

A nanophosphor of LiF:Mg,Cu,Ag was prepared by planetary ball milling for the first time in the laboratory. The size and shape of the nanophosphor were confirmed by XRD and SEM, which showed that it was cubic in shape and ~53 nm in size. The thermoluminescence (TL) characteristics of this nanophosphor were then investigated. It was found that the optimum annealing condition was 250°C for 10 min. The TL sensitivity of the prepared nanopowder was less than that of its micropowder counterpart and the TL glow curve structure exhibited several peaks. The LiF:Mg,Cu,Ag nanophosphor exhibited a linear response over a range of doses from 1 Gy to ~10 kGy. From this study, it appears that LiF:Mg,Cu,Ag nanophosphor is a good candidate for dosimetry because of its linearity over a range of doses, low tendency to fade, good repeatability and simple glow curve structure.

Free-standing supramolecular hydrogel objects by reaction-diffusion

PubMed Central

Lovrak, Matija; Hendriksen, Wouter E. J.; Maity, Chandan; Mytnyk, Serhii; van Steijn, Volkert; Eelkema, Rienk; van Esch, Jan H.

2017-01-01

Self-assembly provides access to a variety of molecular materials, yet spatial control over structure formation remains difficult to achieve. Here we show how reaction–diffusion (RD) can be coupled to a molecular self-assembly process to generate macroscopic free-standing objects with control over shape, size, and functionality. In RD, two or more reactants diffuse from different positions to give rise to spatially defined structures on reaction. We demonstrate that RD can be used to locally control formation and self-assembly of hydrazone molecular gelators from their non-assembling precursors, leading to soft, free-standing hydrogel objects with sizes ranging from several hundred micrometres up to centimeters. Different chemical functionalities and gradients can easily be integrated in the hydrogel objects by using different reactants. Our methodology, together with the vast range of organic reactions and self-assembling building blocks, provides a general approach towards the programmed fabrication of soft microscale objects with controlled functionality and shape. PMID:28580948

Life history dependent morphometric variation in stream-dwelling Atlantic salmon

USGS Publications Warehouse

Letcher, B.H.

2003-01-01

The time course of morphometric variation among life histories for stream-dwelling Atlantic salmon (Salmo salar L.) parr (age-0+ to age-2+) was analyzed. Possible life histories were combinations of parr maturity status in the autumn (mature or immature) and age at outmigration (smolt at age-2+ or later age). Actual life histories expressed with enough fish for analysis in the 1997 cohort were immature/age-2+ smolt, mature/age-2 +smolt, and mature/age-2+ non-smolt. Tagged fish were assigned to one of the three life histories and digital pictures from the field were analyzed using landmark-based geometric morphometrics. Results indicated that successful grouping of fish according to life history varied with fish age, but that fish could be grouped before the actual expression of the life histories. By March (age-1+), fish were successfully grouped using a descriptive discriminant function and successful assignment ranged from 84 to 97% for the remainder of stream residence. A jackknife of the discriminant function revealed an average life history prediction success of 67% from age-1+ summer to smolting. Low sample numbers for one of the life histories may have limited prediction success. A MANOVA on the shape descriptors (relative warps) also indicated significant differences in shape among life histories from age-1+ summer through to smolting. Across all samples, shape varied significantly with size. Within samples, shape did not vary significantly with size for samples from December (age-0+) to May (age-1+). During the age-1+ summer however, shape varied significantly with size, but the relationship between shape and size was not different among life histories. In the autumn (age-1+) and winter (age-2+), life history differences explained a significant portion of the change in shape with size. Life history dependent morphometric variation may be useful to indicate the timing of early expressions of life history variation and as a tool to explore temporal and spatial variation in life history expression.

Study of droplet flow in a T-shape microchannel with bottom wall fluctuation

NASA Astrophysics Data System (ADS)

Pang, Yan; Wang, Xiang; Liu, Zhaomiao

2018-03-01

Droplet generation in a T-shape microchannel, with a main channel width of 50 μm , side channel width of 25 μm, and height of 50 μm, is simulated to study the effects of the forced fluctuation of the bottom wall. The periodic fluctuations of the bottom wall are applied on the near junction part of the main channel in the T-shape microchannel. Effects of bottom wall's shape, fluctuation periods, and amplitudes on the droplet generation are covered in the research of this protocol. In the simulation, the average size is affected a little by the fluctuations, but significantly by the fixed shape of the deformed bottom wall, while the droplet size range is expanded by the fluctuations under most of the conditions. Droplet sizes are distributed in a periodic pattern with small amplitude along the relative time when the fluctuation is forced on the bottom wall near the T-junction, while the droplet emerging frequency is not varied by the fluctuation. The droplet velocity is varied by the bottom wall motion, especially under the shorter period and the larger amplitude. When the fluctuation period is similar to the droplet emerging period, the droplet size is as stable as the non-fluctuation case after a development stage at the beginning of flow, while the droplet velocity is varied by the moving wall with the scope up to 80% of the average velocity under the conditions of this investigation.

Surface facial modelling and allometry in relation to sexual dimorphism.

PubMed

Velemínská, J; Bigoni, L; Krajíček, V; Borský, J; Šmahelová, D; Cagáňová, V; Peterka, M

2012-04-01

Sexual dimorphism is responsible for a substantial part of human facial variability, the study of which is essential for many scientific fields ranging from evolution to special biomedical topics. Our aim was to analyse the relationship between size variability and shape facial variability of sexual traits in the young adult Central European population and to construct average surface models of adult males and females. The method of geometric morphometrics allowed not only the identification of dimorphic traits, but also the evaluation of static allometry and the visualisation of sexual facial differences. Facial variability in the studied sample was characterised by a strong relationship between facial size and shape of sexual dimorphic traits. Large size of face was associated with facial elongation and vice versa. Regarding shape sexual dimorphic traits, a wide, vaulted and high forehead in combination with a narrow and gracile lower face were typical for females. Variability in shape dimorphic traits was smaller in females compared to males. For female classification, shape sexual dimorphic traits are more important, while for males the stronger association is with face size. Males generally had a closer inter-orbital distance and a deeper position of the eyes in relation to the facial plane, a larger and wider straight nose and nostrils, and more massive lower face. Using pseudo-colour maps to provide a detailed schematic representation of the geometrical differences between the sexes, we attempted to clarify the reasons underlying the development of such differences. Copyright © 2012 Elsevier GmbH. All rights reserved.

Capillary Origami Inspired Fabrication of Complex 3D Hydrogel Constructs.

PubMed

Li, Moxiao; Yang, Qingzhen; Liu, Hao; Qiu, Mushu; Lu, Tian Jian; Xu, Feng

2016-09-01

Hydrogels have found broad applications in various engineering and biomedical fields, where the shape and size of hydrogels can profoundly influence their functions. Although numerous methods have been developed to tailor 3D hydrogel structures, it is still challenging to fabricate complex 3D hydrogel constructs. Inspired by the capillary origami phenomenon where surface tension of a droplet on an elastic membrane can induce spontaneous folding of the membrane into 3D structures along with droplet evaporation, a facile strategy is established for the fabrication of complex 3D hydrogel constructs with programmable shapes and sizes by crosslinking hydrogels during the folding process. A mathematical model is further proposed to predict the temporal structure evolution of the folded 3D hydrogel constructs. Using this model, precise control is achieved over the 3D shapes (e.g., pyramid, pentahedron, and cube) and sizes (ranging from hundreds of micrometers to millimeters) through tuning membrane shape, dimensionless parameter of the process (elastocapillary number Ce ), and evaporation time. This work would be favorable to multiple areas, such as flexible electronics, tissue regeneration, and drug delivery. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamics of nanoparticle morphology under low energy ion irradiation.

PubMed

Holland-Moritz, Henry; Graupner, Julia; Möller, Wolfhard; Pacholski, Claudia; Ronning, Carsten

2018-08-03

If nanostructures are irradiated with energetic ions, the mechanism of sputtering becomes important when the ion range matches about the size of the nanoparticle. Gold nanoparticles with diameters of ∼50 nm on top of silicon substrates with a native oxide layer were irradiated by gallium ions with energies ranging from 1 to 30 keV in a focused ion beam system. High resolution in situ scanning electron microscopy imaging permits detailed insights in the dynamics of the morphology change and sputter yield. Compared to bulk-like structures or thin films, a pronounced shaping and enhanced sputtering in the nanostructures occurs, which enables a specific shaping of these structures using ion beams. This effect depends on the ratio of nanoparticle size and ion energy. In the investigated energy regime, the sputter yield increases at increasing ion energy and shows a distinct dependence on the nanoparticle size. The experimental findings are directly compared to Monte Carlo simulations obtained from iradina and TRI3DYN, where the latter takes into account dynamic morphological and compositional changes of the target.

Shape-dependence of the thermal and photochemical reactions of methanol on nanocrystalline anatase TiO2

NASA Astrophysics Data System (ADS)

Bennett, David A.; Cargnello, Matteo; Diroll, Benjamin T.; Murray, Christopher B.; Vohs, John M.

2016-12-01

Structure-activity relationships and the influence of particle size and shape on the partial- and photo-oxidation of methanol on nanocrystalline anatase TiO2 were investigated using temperature-programmed desorption. The study employed two distinct nanoparticle morphologies: truncated bipyramids exposing primarily {101} facets, and flatter platelets exposing primarily {001} surfaces, whose nominal sizes ranged from 10 to 25 nm. The platelets were found to be more active for thermally-driven reactions, such as coupling of methoxide groups to produce dimethyl ether, and deoxygenation to produce methane. A dependence of the reactivity of {001} facets for the coupling of methoxide groups to produce dimethyl ether on facet size was also observed. In contrast to the thermally-driven reactions, the bipyramidal nanoparticles were observed to be more active for a range of photochemical reactions, including oxidation and coupling to produce methyl formate, and photo-decomposition of surface methoxide species. This study also shows how well-defined nanocrystals can be used to help bridge the materials gap between studies of single crystal model catalysts and their high surface area industrial analogs.

Determining the functional form of density dependence: deductive approaches for consumer-resource systems having a single resource.

PubMed

Abrams, Peter A

2009-09-01

Consumer-resource models are used to deduce the functional form of density dependence in the consumer population. A general approach to determining the form of consumer density dependence is proposed; this involves determining the equilibrium (or average) population size for a series of different harvest rates. The relationship between a consumer's mortality and its equilibrium population size is explored for several one-consumer/one-resource models. The shape of density dependence in the resource and the shape of the numerical and functional responses all tend to be "inherited" by the consumer's density dependence. Consumer-resource models suggest that density dependence will very often have both concave and convex segments, something that is impossible under the commonly used theta-logistic model. A range of consumer-resource models predicts that consumer population size often declines at a decelerating rate with mortality at low mortality rates, is insensitive to or increases with mortality over a wide range of intermediate mortalities, and declines at a rapidly accelerating rate with increased mortality when mortality is high. This has important implications for management and conservation of natural populations.

SERS properties of different sized and shaped gold nanoparticles biosynthesized under different environmental conditions by Neurospora crassa extract.

PubMed

Quester, Katrin; Avalos-Borja, Miguel; Vilchis-Nestor, Alfredo Rafael; Camacho-López, Marco Antonio; Castro-Longoria, Ernestina

2013-01-01

Surface-enhanced Raman scattering (SERS) is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces. It is known that metal nanoparticles, especially gold and silver nanoparticles, exhibit great SERS properties, which make them very attractive for the development of biosensors and biocatalysts. On the other hand, the development of ecofriendly methods for the synthesis of metallic nanostructures has become the focus of research in several countries, and many microorganisms and plants have already been used to biosynthesize metallic nanostructures. However, the majority of these are pathogenic to plants or humans. Here, we report gold nanoparticles with good SERS properties, biosynthesized by Neurospora crassa extract under different environmental conditions, increasing Raman signals up to 40 times using methylene blue as a target molecule. Incubation of tetrachloroauric acid solution with the fungal extract at 60°C and a pH value of a) 3, b) 5.5, and c) 10 resulted in the formation of gold nanoparticles of a) different shapes like triangles, hexagons, pentagons etc. in a broad size range of about 10-200 nm, b) mostly quasi-spheres with some different shapes in a main size range of 6-23 nm, and c) only quasi-spheres of 3-12 nm. Analyses included TEM, HRTEM, and EDS in order to corroborate the shape and the elemental character of the gold nanoparticles, respectively. The results presented here show that these 'green' synthesized gold nanoparticles might have potential applicability in the field of biological sensing.

SERS Properties of Different Sized and Shaped Gold Nanoparticles Biosynthesized under Different Environmental Conditions by Neurospora crassa Extract

PubMed Central

Quester, Katrin; Avalos-Borja, Miguel; Vilchis-Nestor, Alfredo Rafael; Camacho-López, Marco Antonio; Castro-Longoria, Ernestina

2013-01-01

Surface-enhanced Raman scattering (SERS) is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces. It is known that metal nanoparticles, especially gold and silver nanoparticles, exhibit great SERS properties, which make them very attractive for the development of biosensors and biocatalysts. On the other hand, the development of ecofriendly methods for the synthesis of metallic nanostructures has become the focus of research in several countries, and many microorganisms and plants have already been used to biosynthesize metallic nanostructures. However, the majority of these are pathogenic to plants or humans. Here, we report gold nanoparticles with good SERS properties, biosynthesized by Neurospora crassa extract under different environmental conditions, increasing Raman signals up to 40 times using methylene blue as a target molecule. Incubation of tetrachloroauric acid solution with the fungal extract at 60°C and a pH value of a) 3, b) 5.5, and c) 10 resulted in the formation of gold nanoparticles of a) different shapes like triangles, hexagons, pentagons etc. in a broad size range of about 10-200 nm, b) mostly quasi-spheres with some different shapes in a main size range of 6-23 nm, and c) only quasi-spheres of 3-12 nm. Analyses included TEM, HRTEM, and EDS in order to corroborate the shape and the elemental character of the gold nanoparticles, respectively. The results presented here show that these ‘green’ synthesized gold nanoparticles might have potential applicability in the field of biological sensing. PMID:24130891

Gold-Copper alloy “nano-dumplings” with tunable compositions and plasmonic properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verma, Manoj, E-mail: duplasmonic@gmail.com; Kedia, Abhitosh; Kumar, P. Senthil

The unique yet tunable optical properties of plasmonic metal nanoparticles have made them attractive targets for a wide range of applications including nanophotonics, molecular sensing, catalysis etc. Such diverse applications that require precisely stable / reproducible plasmonic properties depend sensitively on the particle morphology ie. the shape, size and constituents. Herein, we systematically study the size / shape controlled synthesis of gold-copper “dumpling” shaped alloy nanoparticles by simultaneous reduction of gold and copper salts in the PVP-methanol solute-solvent system, by effectively utilizing the efficient but mild reduction as well as capping abilities of Poly (N-vinylpyrrolidone). Introduction of copper salts notmore » only yielded the alloy nanoparticles, but also slowed down the growth process to maintain high mono-dispersity of the new shapes evolved. Copper and gold has different lattice constants (0.361 and 0.408 nm respectively) and hence doping/addition/replacement of copper atoms to gold FCC unit cell introduces strain into the lattice which is key parameter to the shape evolution in anisotropic nanoparticles. Synthesized alloy nanoparticles were characterized by UV-visible absorption spectroscopy, XRD and TEM imaging.« less

Gold-Copper alloy "nano-dumplings" with tunable compositions and plasmonic properties

NASA Astrophysics Data System (ADS)

Verma, Manoj; Kedia, Abhitosh; Kumar, P. Senthil

2016-05-01

The unique yet tunable optical properties of plasmonic metal nanoparticles have made them attractive targets for a wide range of applications including nanophotonics, molecular sensing, catalysis etc. Such diverse applications that require precisely stable / reproducible plasmonic properties depend sensitively on the particle morphology ie. the shape, size and constituents. Herein, we systematically study the size / shape controlled synthesis of gold-copper "dumpling" shaped alloy nanoparticles by simultaneous reduction of gold and copper salts in the PVP-methanol solute-solvent system, by effectively utilizing the efficient but mild reduction as well as capping abilities of Poly (N-vinylpyrrolidone). Introduction of copper salts not only yielded the alloy nanoparticles, but also slowed down the growth process to maintain high mono-dispersity of the new shapes evolved. Copper and gold has different lattice constants (0.361 and 0.408 nm respectively) and hence doping/addition/replacement of copper atoms to gold FCC unit cell introduces strain into the lattice which is key parameter to the shape evolution in anisotropic nanoparticles. Synthesized alloy nanoparticles were characterized by UV-visible absorption spectroscopy, XRD and TEM imaging.

Fitness consequences of artificial selection on relative male genital size

PubMed Central

Booksmythe, Isobel; Head, Megan L.; Keogh, J. Scott; Jennions, Michael D.

2016-01-01

Male genitalia often show remarkable differences among related species in size, shape and complexity. Across poeciliid fishes, the elongated fin (gonopodium) that males use to inseminate females ranges from 18 to 53% of body length. Relative genital size therefore varies greatly among species. In contrast, there is often tight within-species allometric scaling, which suggests strong selection against genital–body size combinations that deviate from a species' natural line of allometry. We tested this constraint by artificially selecting on the allometric intercept, creating lines of males with relatively longer or shorter gonopodia than occur naturally for a given body size in mosquitofish, Gambusia holbrooki. We show that relative genital length is heritable and diverged 7.6–8.9% between our up-selected and down-selected lines, with correlated changes in body shape. However, deviation from the natural line of allometry does not affect male success in assays of attractiveness, swimming performance and, crucially, reproductive success (paternity). PMID:27188478

Control of peptide nanotube diameter by chemical modifications of an aromatic residue involved in a single close contact

PubMed Central

Tarabout, Christophe; Roux, Stéphane; Gobeaux, Frédéric; Fay, Nicolas; Pouget, Emilie; Meriadec, Cristelle; Ligeti, Melinda; Thomas, Daniel; IJsselstijn, Maarten; Besselievre, François; Buisson, David-Alexandre; Verbavatz, Jean-Marc; Petitjean, Michel; Valéry, Céline; Perrin, Lionel; Rousseau, Bernard; Artzner, Franck; Paternostre, Maité; Cintrat, Jean-Christophe

2011-01-01

Supramolecular self-assembly is an attractive pathway for bottom-up synthesis of novel nanomaterials. In particular, this approach allows the spontaneous formation of structures of well-defined shapes and monodisperse characteristic sizes. Because nanotechnology mainly relies on size-dependent physical phenomena, the control of monodispersity is required, but the possibility of tuning the size is also essential. For self-assembling systems, shape, size, and monodispersity are mainly settled by the chemical structure of the building block. Attempts to change the size notably by chemical modification usually end up with the loss of self-assembly. Here, we generated a library of 17 peptides forming nanotubes of monodisperse diameter ranging from 10 to 36 nm. A structural model taking into account close contacts explains how a modification of a few Å of a single aromatic residue induces a fourfold increase in nanotube diameter. The application of such a strategy is demonstrated by the formation of silica nanotubes of various diameters. PMID:21518895

Axially adjustable magnetic properties in arrays of multilayered Ni/Cu nanowires with variable segment sizes

NASA Astrophysics Data System (ADS)

Shirazi Tehrani, A.; Almasi Kashi, M.; Ramazani, A.; Montazer, A. H.

2016-07-01

Arrays of multilayered Ni/Cu nanowires (NWs) with variable segment sizes were fabricated into anodic aluminum oxide templates using a pulsed electrodeposition method in a single bath for designated potential pulse times. Increasing the pulse time between 0.125 and 2 s in the electrodeposition of Ni enabled the formation of segments with thicknesses ranging from 25 to 280 nm and 10-110 nm in 42 and 65 nm diameter NWs, respectively, leading to disk-shaped, rod-shaped and/or near wire-shaped geometries. Using hysteresis loop measurements at room temperature, the axial and perpendicular magnetic properties were investigated. Regardless of the segment geometry, the axial coercivity and squareness significantly increased with increasing Ni segment thickness, in agreement with a decrease in calculated demagnetizing factors along the NW length. On the contrary, the perpendicular magnetic properties were found to be independent of the pulse times, indicating a competition between the intrawire interactions and the shape demagnetizing field.

Adequacy of different experimental designs for eucalyptus spacing trials in Portuguese environmental conditions

Treesearch

Paula Soares; Margarida Tome

2000-01-01

In Portugal, several eucalyptus spacing trials cover a relatively broad range of experimental designs: trials with a non-randomized block design with plots of different size and number of trees per plot; trials based on a non-systematic design in which spacings were randomized resulting in a factorial arrangement with plots of different size and shape and equal number...

A novel polymer extrusion micropelletization process

NASA Astrophysics Data System (ADS)

Aquite, William

Polymer micropellets provide a variety of potential applications for different processes in the polymer industry. Conventional pellets are in the size range of 2.5 mm to 5 mm, while micropellets are at least ten times smaller, in the size range of 50 μm to 1000 μm. The potential benefits to a processor using micropellets include: high surface to volume ratio, high bulk density, fast and even melting rates in extrusion, improved dry flow properties, faster injection molding cycles, and consequently lower energy consumption during processing. More specialized sintering processes that require polymer powders, such as selective sintering techniques, microporous plastics parts manufacturing, and other powder sintering methods would benefit from the production of polymer micropellets since these exhibit the advantages of pellets yet have a lower average size. This work focuses on the study of a technique developed at the Polymer Engineering Center. The technique uses a microcapillary die for the production of micropellets by causing instabilities in extruded polymer threads deformed using an air stream. Tuning of process conditions allow the development of surface disturbances that promote breakup of the threads into pellets, which are subsequently cooled and collected. Although micropellets with high sphericity and a narrow size distribution can be produced using this technique, minimal changes in process conditions also lead to the production of lenticular pellets as well as pellets, fibers and threads with a wide range of size and shape distributions. This work shows how changing processing conditions achieve a variety of shapes and sizes of micropellets, broadening its application for the production of powders from a variety of polymer resins. Different approaches were used, including dimensional analysis and numerical simulation of the micropelletization process. This research reveals the influence of non-linear viscoelastic effects on the dispersion of a polymer thread through surface disturbances. Furthermore, this research reveals how processing parameters can influence the quality of the produced micropellet. Through this work, an economically feasible technique was developed that can produce the raw material for processors that depend on polymer powders that will deliver ideally shaped and distributed micropellets.

Illustrating ontogenetic change in the dentition of the Nile monitor lizard, Varanus niloticus: a case study in the application of geometric morphometric methods for the quantification of shape-size heterodonty.

PubMed

D'Amore, Domenic C

2015-05-01

Many recent attempts have been made to quantify heterodonty in non-mammalian vertebrates, but the majority of these are limited to Euclidian measurements. One taxon frequently investigated is Varanus niloticus, the Nile monitor. Juveniles possess elongate, pointed teeth (caniniform) along the entirety of the dental arcade, whereas adults develop large, bulbous distal teeth (molariform). The purpose of this study was to present a geometric morphometric method to quantify V. niloticus heterodonty through ontogeny that may be applied to other non-mammalian taxa. Data were collected from the entire tooth row of 19 dry skull specimens. A semilandmark analysis was conducted on the outline of the photographed teeth, and size and shape were derived. Width was also measured with calipers. From these measures, sample ranges and allometric functions were created using multivariate statistical analyses for each tooth position separately, as well as overall measures of heterodonty for each specimen based on morphological disparity. The results confirm and expand upon previous studies, showing measurable shape-size heterodonty in the species with significant differences at each tooth position. Tooth size increases with body size at most positions, and the allometric coefficient increases at more distal positions. Width shows a dramatic increase at the distal positions with ontogeny, often displaying pronounced positive allometry. Dental shape varied in two noticeable ways, with the first composing the vast majority of shape variance: (i) caniniformy vs. molariformy and (ii) mesially leaning, 'rounded' apices vs. distally leaning, 'pointed' apices. The latter was twice as influential in the mandible, a consequence of host bone shape. Mesial teeth show no significant shape change with growth, whereas distal teeth change significantly due primarily to an increase in molariformy. Overall, heterodonty increases with body size concerning both tooth size and shape, but shape heterodonty changes in the mandible are much less pronounced. Although it is unclear to what degree V. niloticus specializes in hard prey items (durophagy), previous studies of varanid feeding behavior, along with research on analogous durophagous vertebrates, indicate a division of labor along the tooth row in adults, due to a possible transition to at least a partial durophagous niche. The geometric morphometric method proposed here, although not without its own limitations, may be ideal for use with a number of dental morphotypes in the future. © 2015 Anatomical Society.

Size and shape effects on diffusion and absorption of colloidal particles near a partially absorbing sphere: implications for uptake of nanoparticles in animal cells.

PubMed

Shi, Wendong; Wang, Jizeng; Fan, Xiaojun; Gao, Huajian

2008-12-01

A mechanics model describing how a cell membrane with diffusive mobile receptors wraps around a ligand-coated cylindrical or spherical particle has been recently developed to model the role of particle size in receptor-mediated endocytosis. The results show that particles in the size range of tens to hundreds of nanometers can enter cells even in the absence of clathrin or caveolin coats. Here we report further progress on modeling the effects of size and shape in diffusion, interaction, and absorption of finite-sized colloidal particles near a partially absorbing sphere. Our analysis indicates that, from the diffusion and interaction point of view, there exists an optimal hydrodynamic size of particles, typically in the nanometer regime, for the maximum rate of particle absorption. Such optimal size arises as a result of balance between the diffusion constant of the particles and the interaction energy between the particles and the absorbing sphere relative to the thermal energy. Particles with a smaller hydrodynamic radius have larger diffusion constant but weaker interaction with the sphere while larger particles have smaller diffusion constant but stronger interaction with the sphere. Since the hydrodynamic radius is also determined by the particle shape, an optimal hydrodynamic radius implies an optimal size as well as an optimal aspect ratio for a nonspherical particle. These results show broad agreement with experimental observations and may have general implications on interaction between nanoparticles and animal cells.

Size and shape effects on diffusion and absorption of colloidal particles near a partially absorbing sphere: Implications for uptake of nanoparticles in animal cells

NASA Astrophysics Data System (ADS)

Shi, Wendong; Wang, Jizeng; Fan, Xiaojun; Gao, Huajian

2008-12-01

A mechanics model describing how a cell membrane with diffusive mobile receptors wraps around a ligand-coated cylindrical or spherical particle has been recently developed to model the role of particle size in receptor-mediated endocytosis. The results show that particles in the size range of tens to hundreds of nanometers can enter cells even in the absence of clathrin or caveolin coats. Here we report further progress on modeling the effects of size and shape in diffusion, interaction, and absorption of finite-sized colloidal particles near a partially absorbing sphere. Our analysis indicates that, from the diffusion and interaction point of view, there exists an optimal hydrodynamic size of particles, typically in the nanometer regime, for the maximum rate of particle absorption. Such optimal size arises as a result of balance between the diffusion constant of the particles and the interaction energy between the particles and the absorbing sphere relative to the thermal energy. Particles with a smaller hydrodynamic radius have larger diffusion constant but weaker interaction with the sphere while larger particles have smaller diffusion constant but stronger interaction with the sphere. Since the hydrodynamic radius is also determined by the particle shape, an optimal hydrodynamic radius implies an optimal size as well as an optimal aspect ratio for a nonspherical particle. These results show broad agreement with experimental observations and may have general implications on interaction between nanoparticles and animal cells.

Comparison of Impact Crater Size-Frequency Distributions (SFD) on Saturnian Satellites with Other Solar-System Bodies

NASA Astrophysics Data System (ADS)

Schmedemann, N.; Neukum, G.; Denk, T.; Wagner, R.; Hartmann, O.

2009-04-01

The examination of the geologic history of the saturnian satellites is a major goal of the Cassini imaging experiment (ISS) [5]. The study of the impact crater-SFD is necessary to derive ages of the saturnian satellite surface units. Furthermore it can be used for resolving the main impactor source and the impactor orbital characteristics for understanding the nature of the bombardment. While large and old areas are suited to measure the branch of large crater sizes, smaller craters can be found in a state of production only at relatively young areas on the saturnian satellites. The impact-crater SFD is derived only from such crater populations which are in production. Hence the measurement of the whole production function in one specific area is impossible. Therefore we have to measure it piece-wise in crater size range in a number of suitable areas. On Iapetus the production function has been measured in seven crater size range pieces, covering a crater size range from 0.15 km to 700 km. At the same crater size, these areas have somewhat different crater frequencies, since they are of different ages. The crater frequency differences of the respective pieces to each other have to be taken out, in order to obtain continuous curves. We have achieved that by normalizing the frequencies measured on the older surface units at the respective smallest crater sizes to the tail ends of the crater frequencies for the largest craters on the younger surface units. The resulting continuous curves give us a reliable production SFD over the whole accessible range. Doing so, we assumed that the production SFD has not changed over time in the parts of the SFD not directly accessible by measurement. Hence the resulting SFD curve is a consequence of a compilation of measurements taken in different areas. Intensive analyses of the crater diameter SFD of the lunar surface have revealed a characteristic W-shaped curve, when it is R-plotted. Crater counting on other planetary surfaces such as Mercury, Venus, Mars, Gaspra, Callisto, Ganymede and Mimas have revealed similarly shaped crater diameter SFDs e.g. [4]. While those SFD curves are equally shaped, the whole curves with their characteristic W-shapes appear to be shifted along the diameter axis. Most likely, this shift is primarily the result of different impact velocities. Other factors of scaling relationships between crater diameter and projectile diameter such as density and gravity on different target bodies are of secondary importance. The measurements of the crater diameter SFD on the saturnian satellites Tethys, Dione, Rhea, and Iapetus also show high similarities to the lunar W-shaped curve. The most complete and statistically valid data set was generated in the case of Iapetus. We have been able to measure crater sizes over four orders of magnitude. The most likely impactor source for the craters in the inner solar system is the asteroid belt orbiting the sun between Mars and Jupiter e.g. [3],[4]. The asteroid body diameter SFD has more recently been analyzed by [2] using the latest discoveries and the absolute geometric albedo of the asteroids. Those albedo values have been converted to asteroid-body diameters using the method of [1]. The body SFD of the asteroid belt in the range from its inner border out to the 5:2 resonance gap gives a very good match to the lunar SFD. The same W-shape characteristics is found at the jovian and saturnian satellite SFD curves as mentioned earlier. Based on these observations and similarities, it is reasonable to suspect asteroids as the major contribution for the outer solar system bombardment in the range of Saturn as well. References: [1]Fowler & Chillemi (1992) in "The IRAS minor planet survey" [2]Ivanov at al. (2002) in „Asteroids III"; The University of Arizona Press: 89-101 [3]Neukum (1983) Habilitation Thesis, "Meteoritenbombardement und Datierung planetarer Oberflächen"; Ludwig-Maximilians-University of Munich. [4]Neukum & Ivanov (1994) in "Hazards due to comets & Asteroids"; The University of Arizona Press: 359-416 [5]Porco et al. (2004) Space Science Reviews 115: 363-497

Assessment of the accuracy of plasma shape reconstruction by the Cauchy condition surface method in JT-60SA

NASA Astrophysics Data System (ADS)

Miyata, Y.; Suzuki, T.; Takechi, M.; Urano, H.; Ide, S.

2015-07-01

For the purpose of stable plasma equilibrium control and detailed analysis, it is essential to reconstruct an accurate plasma boundary on the poloidal cross section in tokamak devices. The Cauchy condition surface (CCS) method is a numerical approach for calculating the spatial distribution of the magnetic flux outside a hypothetical surface and reconstructing the plasma boundary from the magnetic measurements located outside the plasma. The accuracy of the plasma shape reconstruction has been assessed by comparing the CCS method and an equilibrium calculation in JT-60SA with a high elongation and triangularity of plasma shape. The CCS, on which both Dirichlet and Neumann conditions are unknown, is defined as a hypothetical surface located inside the real plasma region. The accuracy of the plasma shape reconstruction is sensitive to the CCS free parameters such as the number of unknown parameters and the shape in JT-60SA. It is found that the optimum number of unknown parameters and the size of the CCS that minimizes errors in the reconstructed plasma shape are in proportion to the plasma size. Furthermore, it is shown that the accuracy of the plasma shape reconstruction is greatly improved using the optimum number of unknown parameters and shape of the CCS, and the reachable reconstruction errors in plasma shape and locations of strike points are within the target ranges in JT-60SA.

Characterizing string-of-pearls colloidal silica by multidetector hydrodynamic chromatography and comparison to multidetector size-exclusion chromatography, off-line multiangle static light scattering, and transmission electron microscopy.

PubMed

Brewer, Amandaa K; Striegel, André M

2011-04-15

The string-of-pearls-type morphology is ubiquitous, manifesting itself variously in proteins, vesicles, bacteria, synthetic polymers, and biopolymers. Characterizing the size and shape of analytes with such morphology, however, presents a challenge, due chiefly to the ease with which the "strings" can be broken during chromatographic analysis or to the paucity of information obtained from the benchmark microscopy and off-line light scattering methods. Here, we address this challenge with multidetector hydrodynamic chromatography (HDC), which has the ability to determine, simultaneously, the size, shape, and compactness and their distributions of string-of-pearls samples. We present the quadruple-detector HDC analysis of colloidal string-of-pearls silica, employing static multiangle and quasielastic light scattering, differential viscometry, and differential refractometry as detection methods. The multidetector approach shows a sample that is broadly polydisperse in both molar mass and size, with strings ranging from two to five particles, but which also contains a high concentration of single, unattached "pearls". Synergistic combination of the various size parameters obtained from the multiplicity of detectors employed shows that the strings with higher degrees of polymerization have a shape similar to the theory-predicted shape of a Gaussian random coil chain of nonoverlapping beads, while the strings with lower degrees of polymerization have a prolate ellipsoidal shape. The HDC technique is contrasted experimentally with multidetector size-exclusion chromatography, where, even under extremely gentle conditions, the strings still degraded during analysis. Such degradation is shown to be absent in HDC, as evidenced by the fact that the molar mass and radius of gyration obtained by HDC with multiangle static light scattering detection (HDC/MALS) compare quite favorably to those determined by off-line MALS analysis under otherwise identical conditions. The multidetector HDC results were also comparable to those obtained by transmission electron microscopy (TEM). Unlike off-line MALS or TEM, however, multidetector HDC is able to provide complete particle analysis based on the molar mass, size, shape, and compactness and their distributions for the entire sample population in less than 20 min. © 2011 American Chemical Society

Using 3D printed eggs to examine the egg-rejection behaviour of wild birds

PubMed Central

Nunez, Valerie; Voss, Henning U.; Croston, Rebecca; Aidala, Zachary; López, Analía V.; Van Tatenhove, Aimee; Holford, Mandë E.; Shawkey, Matthew D.; Hauber, Mark E.

2015-01-01

The coevolutionary relationships between brood parasites and their hosts are often studied by examining the egg rejection behaviour of host species using artificial eggs. However, the traditional methods for producing artificial eggs out of plasticine, plastic, wood, or plaster-of-Paris are laborious, imprecise, and prone to human error. As an alternative, 3D printing may reduce human error, enable more precise manipulation of egg size and shape, and provide a more accurate and replicable protocol for generating artificial stimuli than traditional methods. However, the usefulness of 3D printing technology for egg rejection research remains to be tested. Here, we applied 3D printing technology to the extensively studied egg rejection behaviour of American robins, Turdus migratorius. Eggs of the robin’s brood parasites, brown-headed cowbirds, Molothrus ater, vary greatly in size and shape, but it is unknown whether host egg rejection decisions differ across this gradient of natural variation. We printed artificial eggs that encompass the natural range of shapes and sizes of cowbird eggs, painted them to resemble either robin or cowbird egg colour, and used them to artificially parasitize nests of breeding wild robins. In line with previous studies, we show that robins accept mimetically coloured and reject non-mimetically coloured artificial eggs. Although we found no evidence that subtle differences in parasitic egg size or shape affect robins’ rejection decisions, 3D printing will provide an opportunity for more extensive experimentation on the potential biological or evolutionary significance of size and shape variation of foreign eggs in rejection decisions. We provide a detailed protocol for generating 3D printed eggs using either personal 3D printers or commercial printing services, and highlight additional potential future applications for this technology in the study of egg rejection. PMID:26038720

Geographic location and phylogeny are the main determinants of the size of the geographical range in aquatic beetles

PubMed Central

2011-01-01

Background Why some species are widespread while others are very restricted geographically is one of the most basic questions in biology, although it remains largely unanswered. This is particularly the case for groups of closely related species, which often display large differences in the size of the geographical range despite sharing many other factors due to their common phylogenetic inheritance. We used ten lineages of aquatic Coleoptera from the western Palearctic to test in a comparative framework a broad set of possible determinants of range size: species' age, differences in ecological tolerance, dispersal ability and geographic location. Results When all factors were combined in multiple regression models between 60-98% of the variance was explained by geographic location and phylogenetic signal. Maximum latitudinal and longitudinal limits were positively correlated with range size, with species at the most northern latitudes and eastern longitudes displaying the largest ranges. In lineages with lotic and lentic species, the lentic (better dispersers) display larger distributional ranges than the lotic species (worse dispersers). The size of the geographical range was also positively correlated with the extent of the biomes in which the species is found, but we did not find evidence of a clear relationship between range size and age of the species. Conclusions Our findings show that range size of a species is shaped by an interplay of geographic and ecological factors, with a phylogenetic component affecting both of them. The understanding of the factors that determine the size and geographical location of the distributional range of species is fundamental to the study of the origin and assemblage of the current biota. Our results show that for this purpose the most relevant data may be the phylogenetic history of the species and its geographical location. PMID:22122885

Sexual dimorphism in America: geometric morphometric analysis of the craniofacial region.

PubMed

Kimmerle, Erin H; Ross, Ann; Slice, Dennis

2008-01-01

One of the four pillars of the anthropological protocol is the estimation of sex. The protocol generally consists of linear metric analysis or visually assessing individual skeletal traits on the skull and pelvis based on an ordinal scale of 1-5, ranging from very masculine to very feminine. The morphologic traits are then some how averaged by the investigator to estimate sex. Some skulls may be misclassified because of apparent morphologic features that appear more or less robust due to size differences among individuals. The question of misclassification may be further exemplified in light of comparisons across populations that may differ not only in cranial robusticity but also in stature and general physique. The purpose of this study is to further examine the effect of size and sex on craniofacial shape among American populations to better understand the allometric foundation of skeletal traits currently used for sex estimation. Three-dimensional coordinates of 16 standard craniofacial landmarks were collected using a Microscribe-3DX digitizer. Data were collected for 118 American White and Black males and females from the W.M. Bass Donated Collection and the Forensic Data Bank. The MANCOVA procedure tested shape differences as a function of sex and size. Sex had a significant influence on shape for both American Whites (F = 2.90; d.f. = 19, 39; p > F = 0.0024) and Blacks (F = 2.81; d.f. = 19, 37; p > F = 0.0035), whereas size did not have a significant influence on shape in either Whites (F = 1.69; d.f. = 19, 39; p > F = 0.08) or Blacks (F = 1.09; d.f. = 19, 37; p > F = 0.40). Therefore, for each sex, individuals of various sizes were statistically the same shape. In other words, while significant differences were present between the size of males and females (males on average were larger), there was no size effect beyond that accounted for by sex differences in size. Moreover, the consistency between American groups is interesting as it suggests that population differences in sexual dimorphism may result more from human variation in size than allometric variation in craniofacial morphology.

Size and shape of soil humic acids estimated by viscosity and molecular weight.

PubMed

Kawahigashi, Masayuki; Sumida, Hiroaki; Yamamoto, Kazuhiko

2005-04-15

Ultrafiltration fractions of three soil humic acids were characterized by viscometry and high performance size-exclusion chromatography (HPSEC) in order to estimate shapes and hydrodynamic sizes. Intrinsic viscosities under given solute/solvent/temperature conditions were obtained by extrapolating the concentration dependence of reduced viscosities to zero concentration. Molecular mass (weight average molecular weight (M (w)) and number average molecular weight (M (n))) and hydrodynamic radius (R(H)) were determined by HPSEC using pullulan as calibrant. Values of M (w) and M (n) ranged from 15 to 118 x 10(3) and from 9 to 50 x 10(3) (g mol(-1)), respectively. Polydispersity, as indicated by M (w)/M (n), increased with increasing filter size from 1.5 to 2.4. The hydrodynamic radii (R(H)) ranged between 2.2 and 6.4 nm. For each humic acid, M (w) and [eta] were related. Mark-Houwink coefficients calculated on the basis of the M (w)-[eta] relationships suggested restricted flexible chains for two of the humic acids and a branched structure for the third humic acid. Those structures probably behave as hydrated sphere colloids in a good solvent. Hydrodynamic radii of fractions calculated from [eta] using Einstein's equation, which is applicable to hydrated sphere colloids, ranged from 2.2 to 7.1 nm. These dimensions are fit to the size of nanospaces on and between clay minerals and micropores in soil particle aggregates. On the other hand, the good agreement of R(H) values obtained by applying Einstein's equation with those directly determined by HPSEC suggests that pullulan is a suitable calibrant for estimation of molecular mass and size of humic acids by HPSEC.

Ambient Tropospheric Particles

EPA Science Inventory

Atmospheric particulate matter (PM) is a complex mixture of solid and liquid particles suspended in ambient air (also known as the atmospheric aerosol). Ambient PM arises from a wide-range of sources and/or processes, and consists of particles of different shapes, sizes, and com...

Shape and size engineered cellulosic nanomaterials as broad spectrum anti-microbial compounds.

PubMed

Sharma, Priyanka R; Kamble, Sunil; Sarkar, Dhiman; Anand, Amitesh; Varma, Anjani J

2016-06-01

Oxidized celluloses have been used for decades as antimicrobial wound gauzes and surgical cotton. We now report the successful synthesis of a next generation narrow size range (25-35nm) spherical shaped nanoparticles of 2,3,6-tricarboxycellulose based on cellulose I structural features, for applications as new antimicrobial materials. This study adds to our previous study of 6-carboxycellulose. A wide range of bacteria such as Escherichia coli, Staphloccocus aureus, Bacillus subtilis and Mycobacterium tuberculosis (non-pathogenic as well as pathogenic strains) were affected by these polymers in in vitro studies. Activity against Mycobacteria were noted at high concentrations (MIC99 values 250-1000μg/ml, as compared to anti-TB drug Isoniazid 0.3μg/ml). However, the broad spectrum activity of oxidized celluloses and their nanoparticles against a wide range of bacteria, including Mycobacteria, show that these materials are promising new biocompatible and biodegradable drug delivery vehicles wherein they can play the dual role of being a drug encapsulant as well as a broad spectrum anti-microbial and anti-TB drug. Copyright © 2016. Published by Elsevier B.V.

Development of antifouling surfaces to reduce bacterial attachment

NASA Astrophysics Data System (ADS)

Graham, Mary Viola

Bacteria are exceptionally good at adhering to surfaces and forming complex structures known as biofilms. This process, known as biofouling, can cause problems for infrastructure (eg, clogging and damaging pipes), for the food industry (eg, contamination of processing surfaces and equipment, and for the medical industry (eg, contamination of indwelling medical devices). Accordingly, multiple strategies have been explored to combat biofouling, including chemical modification of surfaces, development of antibiotic coatings, and more recently, the use of engineered surface topography. When designed properly, engineered surface topographies can significantly reduce bacterial surface attachment, ultimately limiting surface colonization. In this work, we hypothesized that the morphology, size, spacing, and surface pre-treatment of topographical features should directly correlate with the size and shape of target organisms, in order to reduce biofouling. Topographical features with size and spacing from 0.25 to 2 mum were fabricated in silicone elastomer and tested against rod shaped bacteria with an average size of 0.5 x 2 mum and spherical bacteria (cocci) ranging from 0.5 - 1 μm in diameter. Antifouling properties of the different topographical features were tested in both static and flow-based assays, and under oxygen plasma-treated (hydrophilic) and untreated (hydrophobic) surface conditions. We found that surface pre-treatment universally affects the ability bacteria to attach to surfaces, while surface topography limits attachment in a manner dependent on the bacterial size/shape and the size/spacing of the topography.

Optical properties of mineral dust aerosol including analysis of particle size, composition, and shape effects, and the impact of physical and chemical processing

NASA Astrophysics Data System (ADS)

Alexander, Jennifer Mary

Atmospheric mineral dust has a large impact on the earth's radiation balance and climate. The radiative effects of mineral dust depend on factors including, particle size, shape, and composition which can all be extremely complex. Mineral dust particles are typically irregular in shape and can include sharp edges, voids, and fine scale surface roughness. Particle shape can also depend on the type of mineral and can vary as a function of particle size. In addition, atmospheric mineral dust is a complex mixture of different minerals as well as other, possibly organic, components that have been mixed in while these particles are suspended in the atmosphere. Aerosol optical properties are investigated in this work, including studies of the effect of particle size, shape, and composition on the infrared (IR) extinction and visible scattering properties in order to achieve more accurate modeling methods. Studies of particle shape effects on dust optical properties for single component mineral samples of silicate clay and diatomaceous earth are carried out here first. Experimental measurements are modeled using T-matrix theory in a uniform spheroid approximation. Previous efforts to simulate the measured optical properties of silicate clay, using models that assumed particle shape was independent of particle size, have achieved only limited success. However, a model which accounts for a correlation between particle size and shape for the silicate clays offers a large improvement over earlier modeling approaches. Diatomaceous earth is also studied as an example of a single component mineral dust aerosol with extreme particle shapes. A particle shape distribution, determined by fitting the experimental IR extinction data, used as a basis for modeling the visible light scattering properties. While the visible simulations show only modestly good agreement with the scattering data, the fits are generally better than those obtained using more commonly invoked particle shape distributions. The next goal of this work is to investigate if modeling methods developed in the studies of single mineral components can be generalized to predict the optical properties of more authentic aerosol samples which are complex mixtures of different minerals. Samples of Saharan sand, Iowa loess, and Arizona road dust are used here as test cases. T-matrix based simulations of the authentic samples, using measured particle size distributions, empirical mineralogies, and a priori particle shape models for each mineral component are directly compared with the measured IR extinction spectra and visible scattering profiles. This modeling approach offers a significant improvement over more commonly applied models that ignore variations in particle shape with size or mineralogy and include only a moderate range of shape parameters. Mineral dust samples processed with organic acids and humic material are also studied in order to explore how the optical properties of dust can change after being aged in the atmosphere. Processed samples include quartz mixed with humic material, and calcite reacted with acetic and oxalic acid. Clear differences in the light scattering properties are observed for all three processed mineral dust samples when compared to the unprocessed mineral dust or organic salt products. These interactions result in both internal and external mixtures depending on the sample. In addition, the presence of these organic materials can alter the mineral dust particle shape. Overall, however, these results demonstrate the need to account for the effects of atmospheric aging of mineral dust on aerosol optical properties. Particle shape can also affect the aerodynamic properties of mineral dust aerosol. In order to account for these effects, the dynamic shape factor is used to give a measure of particle asphericity. Dynamic shape factors of quartz are measured by mass and mobility selecting particles and measuring their vacuum aerodynamic diameter. From this, dynamic shape factors in both the transition and vacuum regime can be derived. The measured dynamic shape factors of quartz agree quite well with the spheroidal shape distributions derived through studies of the optical properties.

The terminal velocity of volcanic particles with shape obtained from 3D X-ray microtomography

NASA Astrophysics Data System (ADS)

Dioguardi, Fabio; Mele, Daniela; Dellino, Pierfrancesco; Dürig, Tobias

2017-01-01

New experiments of falling volcanic particles were performed in order to define terminal velocity models applicable in a wide range of Reynolds number Re. Experiments were carried out with fluids of various viscosities and with particles that cover a wide range of size, density and shape. Particle shape, which strongly influences fluid drag, was measured in 3D by High-resolution X-ray microtomography, by which sphericity Φ3D and fractal dimension D3D were obtained. They are easier to measure and less operator dependent than the 2D shape parameters used in previous papers. Drag laws that make use of the new 3D parameters were obtained by fitting particle data to the experiments, and single-equation terminal velocity models were derived. They work well both at high and low Re (3 × 10- 2 < Re < 104), while earlier formulations made use of different equations at different ranges of Re. The new drag laws are well suited for the modelling of particle transportation both in the eruptive column, where coarse and fine particles are present, and also in the distal part of the umbrella region, where fine ash is involved in the large-scale domains of atmospheric circulation. A table of the typical values of Φ3D and D3D of particles from known plinian, subplinian and ash plume eruptions is presented. Graphs of terminal velocity as a function of grain size are finally proposed as tools to help volcanologists and atmosphere scientists to model particle transportation of explosive eruptions.

Analysis on the stress corrosion crack inception based on pit shape and size of the FV520B tensile specimen

NASA Astrophysics Data System (ADS)

Xiang, Longhao; Pan, Juyi; Chen, Songying

2018-06-01

The influence of pit shape and size on local stress concentration in the tensile specimen and the stress corrosion cracks inception was studied by employing the element remove technique. The maximum stress located in the bottom of pit on FV520B tensile specimen. The location of maximum strain was near the mouth of the pit or the shoulder and plastic strain existed in this region. Stress concentration factor and plastic deformation on four different geometrical shape pits of hemisphere, semi-ellipsoid, bullet and butterfly were numerically investigated, respectively. The simulation results showed that butterfly pit got the biggest stress concentration factor. The plastic strain rate during pit growth was in the sensitivity range of stress corrosion cracks inception, indicating that stress corrosion cracks were more likely to nucleate near the pit tip or the shoulder.

Barlenses and X-shaped features compared: two manifestations of boxy/peanut bulges

NASA Astrophysics Data System (ADS)

Laurikainen, E.; Salo, H.

2017-02-01

Aims: We study the morphological characteristics of boxy/peanut-shaped bulges. In particular, we are interested to determine whether most of the flux associated with bulges in galaxies with masses similar to those of the Milky Way at redshift z 0 might belong to the vertically thick inner part of the bar, in a similar manner as in the Milky Way itself. At high galaxy inclinations, these structures are observed as boxy/peanut/X-shaped features, and when the view is near to face-on, they are observed as barlenses. We also study the possibility that bulges in some fraction of unbarred galaxies might form in a similar manner as the bulges in barred galaxies. Methods: We used the Spitzer Survey of Stellar Structure in Galaxies (S4G) and the Near-IR S0 galaxy Survey (NIRS0S) to compile complete samples of galaxies with barlenses (N = 85) and X-shaped features (N = 88). A sample of unbarred galaxies (N = 41) is also selected. For all 214 galaxies unsharp mask images were created, used to recognize the X-shaped features and to measure their linear sizes. To detect possible boxy isophotes (using the B4-parameter), we also performed an isophotal analysis for the barlens galaxies. We use recently published N-body simulations: the models that exhibit boxy/peanut/X/barlens morphologies are viewed from isotropically chosen directions that cover the full range of galaxy inclinations in the sky. The synthetic images were analyzed in a similar manner as the observations. Results: This is the first time that the observed properties of barlenses and X-shaped features are directly compared across a wide range of galaxy inclinations. A comparison with the simulation models shows that the differences in their apparent sizes, a/rbar ≳ 0.5 for barlenses and a/rbar ≲ 0.5 for X-shapes, can be explained by projection effects. Observations at various inclinations are consistent with intrinsic abl ≈ aX ≈ 0.5rbar: here intrinsic size means the face-on semimajor axis length for bars and barlenses, and the semilength of the X-shape when the bar is viewed exactly edge-on. While X-shapes are quite common at intermediate galaxy inclinations (for I = 40°-60° their frequency is about half that of barlenses), they are seldom observed at smaller inclinations. This is consistent with our simulation models, which have a small compact classical bulge that produces a steep inner rotation slope, whereas bulgeless shallow rotation curve models predict that X-shapes should be visible even in a face-on geometry. The steep rotation curve models are also consistent with the observed trend that B4 is positive at low inclination and with negative values for I ≳ 40°-60°; this implies boxy isophotes. In total, only about one quarter of the barlenses (with I ≤ 60°) show boxy isophotes. Conclusions: Our analyses are consistent with the idea that barlenses and X-shaped features are physically the same phenomenon. However, the observed nearly round face-on barlens morphology is expected only when at least a few percent of the disk mass is located in a central component, within a region much smaller than the size of the barlens itself. Barlenses contribute to secular evolution of galaxies, and might even act as a transition phase between barred and unbarred galaxies. We also discuss that the wide range of stellar population ages obtained for the photometric bulges in the literature are consistent with our interpretation.

Growth mechanics of bacterial cell wall and morphology of bacteria

NASA Astrophysics Data System (ADS)

Jiang, Hongyuan; Sun, Sean

2010-03-01

The peptidoglycan cell wall of bacteria is responsible for maintaining the cell shape and integrity. During the bacterial life cycle, the growth of the cell wall is affected by mechanical stress and osmotic pressure internal to the cell. We develop a theory to describe cell shape changes under the influence of mechanical forces. We find that the theory predicts a steady state size and shape for bacterial cells ranging from cocci to spirillum. Moreover, the theory suggest a mechanism by which bacterial cytoskeletal proteins such as MreB and crescentin can maintain the shape of the cell. The theory can also explain the several recent experiments on growing bacteria in micro-environments.

Interaction location outweighs the competitive advantage of numerical superiority in Cebus capucinus intergroup contests.

PubMed

Crofoot, Margaret C; Gilby, Ian C; Wikelski, Martin C; Kays, Roland W

2008-01-15

Numerical superiority confers a competitive advantage during contests among animal groups, shaping patterns of resource access, and, by extension, fitness. However, relative group size does not always determine the winner of intergroup contests. Smaller, presumably weaker social groups often defeat their larger neighbors, but how and when they are able to do so remains poorly understood. Models of competition between individuals suggest that location may influence contest outcome. However, because of the logistical difficulties of studying intergroup interactions, previous studies have been unable to determine how contest location and group size interact to shape relationships among groups. We address this question by using an automated radio telemetry system to study intergroup interactions among six capuchin monkey (Cebus capucinus) social groups of varying sizes. We find that the odds of winning increase with relative group size; one additional group member increases the odds of winning an interaction by 10%. However, this effect is not uniform across space; with each 100 m that a group moves away from the center of its home range, its odds of winning an interaction decrease by 31%. We demonstrate that contest outcome depends on an interaction between group size and location, such that small groups can defeat much larger groups near the center of their home range. The tendency of resident groups to win contests may help explain how small groups persist in areas with intense intergroup competition.

Urbanization disrupts latitude-size rule in 17-year cicadas.

PubMed

Beasley, DeAnna E; Penick, Clint A; Boateng, Nana S; Menninger, Holly L; Dunn, Robert R

2018-03-01

Many ectotherms show a decrease in body size with increasing latitude due to changes in climate, a pattern termed converse Bergmann's rule. Urban conditions-particularly warmer temperatures and fragmented landscapes-may impose stresses on development that could disrupt these body size patterns. To test the impact of urbanization on development and latitudinal trends in body size, we launched a citizen science project to collect periodical cicadas ( Magicicada septendecim ) from across their latitudinal range during the 2013 emergence of Brood II. Periodical cicadas are long-lived insects whose distribution spans a broad latitudinal range covering both urban and rural habitats. We used a geometric morphometric approach to assess body size and developmental stress based on fluctuating asymmetry in wing shape. Body size of rural cicadas followed converse Bergmann's rule, but this pattern was disrupted in urban habitats. In the north, urban cicadas were larger than their rural counterparts, while southern populations showed little variation in body size between habitats. We detected no evidence of differences in developmental stress due to urbanization. To our knowledge, this is the first evidence that urbanization disrupts biogeographical trends in body size, and this pattern highlights how the effects of urbanization may differ over a species' range.

Morphologically controlled synthesis of ferric oxide nano/micro particles and their catalytic application in dry and wet media: a new approach.

PubMed

Janjua, Muhammad Ramzan Saeed Ashraf; Jamil, Saba; Jahan, Nazish; Khan, Shanza Rauf; Mirza, Saima

2017-05-31

Morphologically controlled synthesis of ferric oxide nano/micro particles has been carried out by using solvothermal route. Structural characterization displays that the predominant morphologies are porous hollow spheres, microspheres, micro rectangular platelets, octahedral and irregular shaped particles. It is also observed that solvent has significant effect on morphology such as shape and size of the particles. All the morphologies obtained by using different solvents are nearly uniform with narrow size distribution range. The values of full width at half maxima (FWHM) of all the products were calculated to compare their size distribution. The FWHM value varies with size of the particles for example small size particles show polydispersity whereas large size particles have shown monodispersity. The size of particles increases with decrease in polarity of the solvent whereas their shape changes from spherical to rectangular/irregular with decrease in polarity of the solvent. The catalytic activities of all the products were investigated for both dry and wet processes such as thermal decomposition of ammonium per chlorate (AP) and reduction of 4-nitrophenol in aqueous media. The results indicate that each product has a tendency to act as a catalyst. The porous hollow spheres decrease the thermal decomposition temperature of AP by 140 °C and octahedral Fe 3 O 4 particles decrease the decomposition temperature by 30 °C. The value of apparent rate constant (k app ) of reduction of 4-NP has also been calculated.

Multi-scale ordering of self-assembled InAs/GaAs(001) quantum dots

PubMed Central

Songmuang, R; Rastelli, A; Heidemeyer, H; Schmidt, OG

2006-01-01

Ordering phenomena related to the self-assembly of InAs quantum dots (QD) grown on GaAs(001) substrates are experimentally investigated on different length scales. On the shortest length-scale studied here, we examine the QD morphology and observe two types of QD shapes, i.e., pyramids and domes. Pyramids are elongated along the [1-10] directions and are bounded by {137} facets, while domes have a multi-facetted shape. By changing the growth rates, we are able to control the size and size homogeneity of freestanding QDs. QDs grown by using low growth rate are characterized by larger sizes and a narrower size distribution. The homogeneity of buried QDs is measured by photoluminescence spectroscopy and can be improved by low temperature overgrowth. The overgrowth induces the formation of nanostructures on the surface. The fabrication of self-assembled nanoholes, which are used as a template to induce short-range positioning of QDs, is also investigated. The growth of closely spaced QDs (QD molecules) containing 2–6 QDs per QD molecule is discussed. Finally, the long-range positioning of self-assembled QDs, which can be achieved by the growth on patterned substrates, is demonstrated. Lateral QD replication observed during growth of three-dimensional QD crystals is reported.

Microwave-assisted synthesis of iron oxide nanoparticles in biocompatible organic environment

NASA Astrophysics Data System (ADS)

Aivazoglou, E.; Metaxa, E.; Hristoforou, E.

2018-04-01

The development of magnetite and maghemite particles in uniform nanometer size has triggered the interest of the research community due to their many interesting properties leading to a wide range of applications, such as catalysis, nanomedicine-nanobiology and other engineering applications. In this study, a simple, time-saving and low energy-consuming, microwave-assisted synthesis of iron oxide nanoparticles, is presented. The nanoparticles were prepared by microwave-assisted synthesis using polyethylene glycol (PEG) or PEG and β-cyclodextrin (β-CD)/water solutions of chloride salts of iron in the presence of ammonia solution. The prepared nano-powders were characterized using X-Ray Diffraction (XRD), Transition Electron Microscopy (TEM), Fourier-transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, Vibrating Sample Magnetometer (VSM), X-Ray Photoelectron Spectroscopy (XPS) and Thermal analysis (TG/DSC). The produced nanoparticles are crystallized mostly in the magnetite and maghemite lattice exhibiting very similar shape and size, with indications of partial PEG coating. Heating time, microwave power and presence of PEG, are the key factors shaping the size properties of nanoparticles. The average size of particles ranges from 10.3 to 19.2 nm. The nanoparticles exhibit a faceted morphology, with zero contamination levels. The magnetic measurements indicate that the powders are soft magnetic materials with negligible coercivity and remanence, illustrating super-paramagnetic behavior.

A scattering database of marine particles and its application in optical analysis

NASA Astrophysics Data System (ADS)

Xu, G.; Yang, P.; Kattawar, G.; Zhang, X.

2016-12-01

In modeling the scattering properties of marine particles (e.g. phytoplankton), the laboratory studies imply a need to properly account for the influence of particle morphology, in addition to size and composition. In this study, a marine particle scattering database is constructed using a collection of distorted hexahedral shapes. Specifically, the scattering properties of each size bin and refractive index are obtained by the ensemble average associated with distorted hexahedra with randomly tilted facets and selected aspect ratios (from elongated to flattened). The randomness degree in shape-generation process defines the geometric irregularity of the particles in the group. The geometric irregularity and particle aspect ratios constitute a set of "shape factors" to be accounted for (e.g. in best-fit analysis). To cover most of the marine particle size range, we combine the Invariant Imbedding T-matrix (II-TM) method and the Physical-Geometric Optics Hybrid (PGOH) method in the calculations. The simulated optical properties are shown and compared with those obtained from Lorenz-Mie Theory. Using the scattering database, we present a preliminary optical analysis of laboratory-measured optical properties of marine particles.

Size and shape dependent deprotonation potential and proton affinity of nanodiamond

NASA Astrophysics Data System (ADS)

Barnard, Amanda S.; Per, Manolo C.

2014-11-01

Many important reactions in biology and medicine involve proton abstraction and transfer, and it is integral to applications such as drug delivery. Unlike electrons, which are quantum mechanically delocalized, protons are instantaneously localized on specific residues in these reactions, which can be a distinct advantage. However, the introduction of nanoparticles, such as non-toxic nanodiamonds, to this field complicates matters, as the number of possible sites increases as the inverse radius of the particle. In this paper we present \\gt {{10}4} simulations that map the size- and shape-dependence of the deprotonation potential and proton affinity of nanodiamonds in the range 1.8-2.7 nm in average diameter. We find that while the average deprotonation potential and proton affinities decrease with size, the site-specific values are inhomogeneous over the surface of the particles, exhibiting strong shape-dependence. The proton affinity is strongly facet-dependent, whereas the deprotonation potential is edge/corner-dependent, which creates a type of spatial hysteresis in the transfer of protons to and from the nanodiamond, and provides new opportunities for selective functionalization.

Effects of sample size on KERNEL home range estimates

USGS Publications Warehouse

Seaman, D.E.; Millspaugh, J.J.; Kernohan, Brian J.; Brundige, Gary C.; Raedeke, Kenneth J.; Gitzen, Robert A.

1999-01-01

Kernel methods for estimating home range are being used increasingly in wildlife research, but the effect of sample size on their accuracy is not known. We used computer simulations of 10-200 points/home range and compared accuracy of home range estimates produced by fixed and adaptive kernels with the reference (REF) and least-squares cross-validation (LSCV) methods for determining the amount of smoothing. Simulated home ranges varied from simple to complex shapes created by mixing bivariate normal distributions. We used the size of the 95% home range area and the relative mean squared error of the surface fit to assess the accuracy of the kernel home range estimates. For both measures, the bias and variance approached an asymptote at about 50 observations/home range. The fixed kernel with smoothing selected by LSCV provided the least-biased estimates of the 95% home range area. All kernel methods produced similar surface fit for most simulations, but the fixed kernel with LSCV had the lowest frequency and magnitude of very poor estimates. We reviewed 101 papers published in The Journal of Wildlife Management (JWM) between 1980 and 1997 that estimated animal home ranges. A minority of these papers used nonparametric utilization distribution (UD) estimators, and most did not adequately report sample sizes. We recommend that home range studies using kernel estimates use LSCV to determine the amount of smoothing, obtain a minimum of 30 observations per animal (but preferably a?Y50), and report sample sizes in published results.

Improvement to microphysical schemes in WRF Model based on observed data, part I: size distribution function

NASA Astrophysics Data System (ADS)

Shan, Y.; Eric, W.; Gao, L.; Zhao, T.; Yin, Y.

2015-12-01

In this study, we have evaluated the performance of size distribution functions (SDF) with 2- and 3-moments in fitting the observed size distribution of rain droplets at three different heights. The goal is to improve the microphysics schemes in meso-scale models, such as Weather Research and Forecast (WRF). Rain droplets were observed during eight periods of different rain types at three stations on the Yellow Mountain in East China. The SDF in this study were M-P distribution with a fixed shape parameter in Gamma SDF(FSP). Where the Gamma SDFs were obtained with three diagnosis methods with the shape parameters based on Milbrandt (2010; denoted DSPM10), Milbrandt (2005; denoted DSPM05) and Seifert (2008; denoted DSPS08) for solving the shape parameter(SSP) and Lognormal SDF. Based on the preliminary experiments, three ensemble methods deciding Gamma SDF was also developed and assessed. The magnitude of average relative error caused by applying a FSP was 10-2 for fitting 0-order moment of the observed rain droplet distribution, and the magnitude of average relative error changed to 10-1 and 100 respectively for 1-4 order moments and 5-6 order moments. To different extent, DSPM10, DSPM05, DSPS08, SSP and ensemble methods could improve fitting accuracies for 0-6 order moments, especially the one coupling SSP and DSPS08 methods, which provided a average relative error 6.46% for 1-4 order moments and 11.90% for 5-6 order moments, respectively. The relative error of fitting three moments using the Lognormal SDF was much larger than that of Gamma SDF. The threshold value of shape parameter ranged from 0 to 8, because values beyond this range could cause overflow in the calculation. When average diameter of rain droplets was less than 2mm, the possibility of unavailable shape parameter value(USPV) increased with a decreasing droplet size. There was strong sensitivity of moment group in fitting accuracy. When ensemble method coupling SSP and DSPS08 was used, a better fit to 1-3-5 moments of the SDF was possible compared to fitting the 0-3-6 moment group.

Food web structure shaped by habitat size and climate across a latitudinal gradient.

PubMed

Romero, Gustavo Q; Piccoli, Gustavo C O; de Omena, Paula M; Gonçalves-Souza, Thiago

2016-10-01

Habitat size and climate are known to affect the trophic structure and dynamics of communities, but their interactive effects are poorly understood. Organisms from different trophic levels vary in terms of metabolic requirements and heat dissipation. Indeed, larger species such as keystone predators require more stable climatic conditions than their prey. Likewise, habitat size disproportionally affects large-sized predators, which require larger home ranges and are thus restricted to larger habitats. Therefore, food web structure in patchy ecosystems is expected to be shaped by habitat size and climate variations. Here we investigate this prediction using natural aquatic microcosm (bromeliad phytotelmata) food webs composed of litter resources (mainly detritus), detritivores, mesopredators, and top predators (damselflies). We surveyed 240 bromeliads of varying sizes (water retention capacity) across 12 open restingas in SE Brazil spread across a wide range of tropical latitudes (-12.6° to -27.6°, ca. 2,000 km) and climates (Δ mean annual temperature = 5.3°C). We found a strong increase in predator-to-detritivore mass ratio with habitat size, which was representative of a typical inverted trophic pyramid in larger ecosystems. However, this relationship was contingent among the restingas; slopes of linear models were steeper in more stable and favorable climates, leading to inverted trophic pyramids (and top-down control) being more pronounced in environments with more favorable climatic conditions. By contrast, detritivore-resource and mesopredator-detritivore mass ratios were not affected by habitat size or climate variations across latitudes. Our results highlight that the combined effects of habitat size, climate and predator composition are pivotal to understanding the impacts of multiple environmental factors on food web structure and dynamics. © 2016 by the Ecological Society of America.

Modeling of Grain Size Distribution of Tsunami Sand Deposits in V-shaped Valley of Numanohama During the 2011 Tohoku Tsunami

NASA Astrophysics Data System (ADS)

Gusman, A. R.; Satake, K.; Goto, T.; Takahashi, T.

2016-12-01

Estimating tsunami amplitude from tsunami sand deposit has been a challenge. The grain size distribution of tsunami sand deposit may have correlation with tsunami inundation process, and further with its source characteristics. In order to test this hypothesis, we need a tsunami sediment transport model that can accurately estimate grain size distribution of tsunami deposit. Here, we built and validate a tsunami sediment transport model that can simulate grain size distribution. Our numerical model has three layers which are suspended load layer, active bed layer, and parent bed layer. The two bed layers contain information about the grain size distribution. This numerical model can handle a wide range of grain sizes from 0.063 (4 ϕ) to 5.657 mm (-2.5 ϕ). We apply the numerical model to simulate the sedimentation process during the 2011 Tohoku earthquake in Numanohama, Iwate prefecture, Japan. The grain size distributions at 15 sample points along a 900 m transect from the beach are used to validate the tsunami sediment transport model. The tsunami deposits are dominated by coarse sand with diameter of 0.5 - 1 mm and their thickness are up to 25 cm. Our tsunami model can well reproduce the observed tsunami run-ups that are ranged from 16 to 34 m along the steep valley in Numanohama. The shapes of the simulated grain size distributions at many sample points located within 300 m from the shoreline are similar to the observations. The differences between observed and simulated peak of grain size distributions are less than 1 ϕ. Our result also shows that the simulated sand thickness distribution along the transect is consistent with the observation.

Heating efficiency dependency on size and morphology of magnetite nanoparticles

NASA Astrophysics Data System (ADS)

Parekh, Kinnari; Parmar, Harshida; Sharma, Vinay; Ramanujan, R. V.

2018-04-01

Different size magnetite nanoparticles ranging from superparamagnetic (9 nm) to single domain (27 nm) and multi domain (53 nm) were synthesized using chemical route. Morphology of these particles as seen from TEM images indicates shape change from spherical to cubic with the growth of particles. The saturation magnetization (σs) and Specific Loss Power (SLP) showed maximum for single domain size, 72 emu/g and 102 W/g, respectively then those of multi domain size particles. These samples show higher SLP at relatively low concentration, low frequency and low amplitude compared to samples prepared by other routes.

Occupancy in continuous habitat

USGS Publications Warehouse

Efford, Murray G.; Dawson, Deanna K.

2012-01-01

The probability that a site has at least one individual of a species ('occupancy') has come to be widely used as a state variable for animal population monitoring. The available statistical theory for estimation when detection is imperfect applies particularly to habitat patches or islands, although it is also used for arbitrary plots in continuous habitat. The probability that such a plot is occupied depends on plot size and home-range characteristics (size, shape and dispersion) as well as population density. Plot size is critical to the definition of occupancy as a state variable, but clear advice on plot size is missing from the literature on the design of occupancy studies. We describe models for the effects of varying plot size and home-range size on expected occupancy. Temporal, spatial, and species variation in average home-range size is to be expected, but information on home ranges is difficult to retrieve from species presence/absence data collected in occupancy studies. The effect of variable home-range size is negligible when plots are very large (>100 x area of home range), but large plots pose practical problems. At the other extreme, sampling of 'point' plots with cameras or other passive detectors allows the true 'proportion of area occupied' to be estimated. However, this measure equally reflects home-range size and density, and is of doubtful value for population monitoring or cross-species comparisons. Plot size is ill-defined and variable in occupancy studies that detect animals at unknown distances, the commonest example being unlimited-radius point counts of song birds. We also find that plot size is ill-defined in recent treatments of "multi-scale" occupancy; the respective scales are better interpreted as temporal (instantaneous and asymptotic) rather than spatial. Occupancy is an inadequate metric for population monitoring when it is confounded with home-range size or detection distance.

Advances in synthesis of calcium phosphate crystals with controlled size and shape.

PubMed

Lin, Kaili; Wu, Chengtie; Chang, Jiang

2014-10-01

Calcium phosphate (CaP) materials have a wide range of applications, including biomaterials, adsorbents, chemical engineering materials, catalysts and catalyst supports and mechanical reinforcements. The size and shape of CaP crystals and aggregates play critical roles in their applications. The main inorganic building blocks of human bones and teeth are nanocrystalline CaPs; recently, much progress has been made in the application of CaP nanocrystals and their composites for clinical repair of damaged bone and tooth. For example, CaPs with special micro- and nanostructures can better imitate the biomimetic features of human bone and tooth, and this offers significantly enhanced biological performances. Therefore, the design of CaP nano-/microcrystals, and the shape and hierarchical structures of CaPs, have great potential to revolutionize the field of hard tissue engineering, starting from bone/tooth repair and augmentation to controlled drug delivery devices. Previously, a number of reviews have reported the synthesis and properties of CaP materials, especially for hydroxyapatite (HAp). However, most of them mainly focused on the characterizations and physicochemical and biological properties of HAp particles. There are few reviews about the control of particle size and size distribution of CaPs, and in particular the control of nano-/microstructures on bulk CaP ceramic surfaces, which is a big challenge technically and may have great potential in tissue engineering applications. This review summarizes the current state of the art for the synthesis of CaP crystals with controlled sizes from the nano- to the macroscale, and the diverse shapes including the zero-dimensional shapes of particles and spheres, the one-dimensional shapes of rods, fibers, wires and whiskers, the two-dimensional shapes of sheets, disks, plates, belts, ribbons and flakes and the three-dimensional (3-D) shapes of porous, hollow, and biomimetic structures similar to biological bone and tooth. In addition, this review will also summarize studies on the controlled formation of nano-/microstructures on the surface of bulk ceramics, and the preparation of macroscopical bone grafts with 3-D architecture nano-/microstructured surfaces. Moreover, the possible directions of future research and development in this field, such as the detailed mechanisms behind the size and shape control in various strategies, the importance of theoretical simulation, self-assembly, biomineralization and sacrificial precursor strategies in the fabrication of biomimetic bone-like and enamel-like CaP materials are proposed. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Size and modal analyses of fines and ultrafines from some Apollo 17 samples

NASA Technical Reports Server (NTRS)

Greene, G. M.; King, D. T., Jr.; Banholzer, G. S., Jr.; King, E. A.

1975-01-01

Scanning electron and optical microscopy techniques have been used to determine the grain-size frequency distributions and morphology-based modal analyses of fine and ultrafine fractions of some Apollo 17 regolith samples. There are significant and large differences between the grain-size frequency distributions of the less than 10-micron size fraction of Apollo 17 samples, but there are no clear relations to the local geologic setting from which individual samples have been collected. This may be due to effective lateral mixing of regolith particles in this size range by micrometeoroid impacts. None of the properties of the frequency distributions support the idea of selective transport of any fine grain-size fraction, as has been proposed by other workers. All of the particle types found in the coarser size fractions also occur in the less than 10-micron particles. In the size range from 105 to 10 microns there is a strong tendency for the percentage of regularly shaped glass to increase as the graphic mean grain size of the less than 1-mm size fraction decreases, both probably being controlled by exposure age.

The interaction of neutral evolutionary processes with climatically-driven adaptive changes in the 3D shape of the human os coxae.

PubMed

Betti, Lia; von Cramon-Taubadel, Noreen; Manica, Andrea; Lycett, Stephen J

2014-08-01

Differences in the breadth of the pelvis among modern human populations and among extinct hominin species have often been interpreted in the light of thermoregulatory adaptation, whereby a larger pelvic girdle would help preserve body temperature in cold environments while a narrower pelvis would help dissipate heat in tropical climates. There is, however, a theoretical problem in interpreting a pattern of variation as evidence of selection without first accounting for the effects of neutral evolutionary processes (i.e., mutation, genetic drift and migration). Here, we analyse 3D configurations of 27 landmarks on the os coxae of 1494 modern human individuals representing 30 male and 23 female populations from five continents and a range of climatic conditions. We test for the effects of climate on the size and shape of the pelvic bone, while explicitly accounting for population history (i.e., geographically-mediated gene flow and genetic drift). We find that neutral processes account for a substantial proportion of shape variance in the human os coxae in both sexes. Beyond the neutral pattern due to population history, temperature is a significant predictor of shape and size variation in the os coxae, at least in males. The effect of climate on the shape of the pelvic bone, however, is comparatively limited, explaining only a small percentage of shape variation in males and females. In accordance with previous hypotheses, the size of the os coxae tends to increase with decreasing temperature, although the significance of the association is reduced when population history is taken into account. In conclusion, the shape and size of the human os coxae reflect both neutral evolutionary processes and climatically-driven adaptive changes. Neutral processes have a substantial effect on pelvic variation, suggesting such factors will need to be taken into account in future studies of human and fossil hominin coxal variation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

NASA Astrophysics Data System (ADS)

Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

2013-12-01

We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

Variability in body size and shape of UK offshore workers: A cluster analysis approach.

PubMed

Stewart, Arthur; Ledingham, Robert; Williams, Hector

2017-01-01

Male UK offshore workers have enlarged dimensions compared with UK norms and knowledge of specific sizes and shapes typifying their physiques will assist a range of functions related to health and ergonomics. A representative sample of the UK offshore workforce (n = 588) underwent 3D photonic scanning, from which 19 extracted dimensional measures were used in k-means cluster analysis to characterise physique groups. Of the 11 resulting clusters four somatotype groups were expressed: one cluster was muscular and lean, four had greater muscularity than adiposity, three had equal adiposity and muscularity and three had greater adiposity than muscularity. Some clusters appeared constitutionally similar to others, differing only in absolute size. These cluster centroids represent an evidence-base for future designs in apparel and other applications where body size and proportions affect functional performance. They also constitute phenotypic evidence providing insight into the 'offshore culture' which may underpin the enlarged dimensions of offshore workers. Copyright © 2016 Elsevier Ltd. All rights reserved.

Vocal tract length and acoustics of vocalization in the domestic dog (Canis familiaris).

PubMed

Riede, T; Fitch, T

1999-10-01

The physical nature of the vocal tract results in the production of formants during vocalisation. In some animals (including humans), receivers can derive information (such as body size) about sender characteristics on the basis of formant characteristics. Domestication and selective breeding have resulted in a high variability in head size and shape in the dog (Canis familiaris), suggesting that there might be large differences in the vocal tract length, which could cause formant behaviour to affect interbreed communication. Lateral radiographs were made of dogs from several breeds ranging in size from a Yorkshire terrier (2.5 kg) to a German shepherd (50 kg) and were used to measure vocal tract length. In addition, we recorded an acoustic signal (growling) from some dogs. Significant correlations were found between vocal tract length, body mass and formant dispersion, suggesting that formant dispersion can deliver information about the body size of the vocalizer. Because of the low correlation between vocal tract length and the first formant, we predict a non-uniform vocal tract shape.

Review and comparison of non-conventional imaging systems for three-dimensional digitization of transparent objects

NASA Astrophysics Data System (ADS)

Mériaudeau, Fabrice; Rantoson, Rindra; Fofi, David; Stolz, Christophe

2012-04-01

Fashion and design greatly influence the conception of manufactured products which now exhibit complex forms and shapes. Two-dimensional quality control procedures (e.g., shape, textures, colors, and 2D geometry) are progressively being replaced by 3D inspection methods (e.g., 3D geometry, colors, and texture on the 3D shape) therefore requiring a digitization of the object surface. Three dimensional surface acquisition is a topic which has been studied to a large extent, and a significant number of techniques for acquiring 3D shapes has been proposed, leading to a wide range of commercial solutions available on the market. These systems cover a wide range from micro-scale objects such as shape from focus and shape from defocus techniques, to several meter sized objects (time of flight technique). Nevertheless, the use of such systems still encounters difficulties when dealing with non-diffuse (non Lambertian) surfaces as is the case for transparent, semi-transparent, or highly reflective materials (e.g., glass, crystals, plastics, and shiny metals). We review and compare various systems and approaches which were recently developed for 3D digitization of transparent objects.

Size and shape in Melipona quadrifasciata anthidioides Lepeletier, 1836 (Hymenoptera; Meliponini).

PubMed

Nunes, L A; Passos, G B; Carvalho, C A L; Araújo, E D

2013-11-01

This study aimed to identify differences in wing shape among populations of Melipona quadrifasciata anthidioides obtained in 23 locations in the semi-arid region of Bahia state (Brazil). Analysis of the Procrustes distances among mean wing shapes indicated that population structure did not determine shape variation. Instead, populations were structured geographically according to wing size. The Partial Mantel Test between morphometric (shape and size) distance matrices and altitude, taking geographic distances into account, was used for a more detailed understanding of size and shape determinants. A partial Mantel test between morphometris (shape and size) variation and altitude, taking geographic distances into account, revealed that size (but not shape) is largely influenced by altitude (r = 0.54 p < 0.01). These results indicate greater evolutionary constraints for the shape variation, which must be directly associated with aerodynamic issues in this structure. The size, however, indicates that the bees tend to have larger wings in populations located at higher altitudes.

Image simulations of quantum dots.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lang, C.; Liao, Xiaozhou; Cockayne, D. J.

2001-01-01

Quantum dot (QD) nanostructures have drawn increased interest in recent years. Their small size leads to quantum confinement of the electrons, which is responsible for their unique electronic and optical properties. They promise to find use in a wide range of devices ranging from semiconductor lasers (Bimberg et al (2001), Ribbat et al (2001)) to quantum computing. The properties of QDs are also determined by their shape and composition. All three parameters (size, shape and composition) have a significant impact on their contrast in the transmission electron microscope (TEM), and consequently the possibility arises that these parameters can be extractedmore » from the images. Zone axis plan view images are especially sensitive to the composition of QDs, and image simulation is an important way to understand how the composition determines the contrast. This paper outlines a method of image simulation of QDs developed by Liao et. al. (1999) and presents an application of the method to QDs in wurtzite InN/GaN.« less

Assessment of the accuracy of plasma shape reconstruction by the Cauchy condition surface method in JT-60SA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miyata, Y.; Suzuki, T.; Takechi, M.

2015-07-15

For the purpose of stable plasma equilibrium control and detailed analysis, it is essential to reconstruct an accurate plasma boundary on the poloidal cross section in tokamak devices. The Cauchy condition surface (CCS) method is a numerical approach for calculating the spatial distribution of the magnetic flux outside a hypothetical surface and reconstructing the plasma boundary from the magnetic measurements located outside the plasma. The accuracy of the plasma shape reconstruction has been assessed by comparing the CCS method and an equilibrium calculation in JT-60SA with a high elongation and triangularity of plasma shape. The CCS, on which both Dirichletmore » and Neumann conditions are unknown, is defined as a hypothetical surface located inside the real plasma region. The accuracy of the plasma shape reconstruction is sensitive to the CCS free parameters such as the number of unknown parameters and the shape in JT-60SA. It is found that the optimum number of unknown parameters and the size of the CCS that minimizes errors in the reconstructed plasma shape are in proportion to the plasma size. Furthermore, it is shown that the accuracy of the plasma shape reconstruction is greatly improved using the optimum number of unknown parameters and shape of the CCS, and the reachable reconstruction errors in plasma shape and locations of strike points are within the target ranges in JT-60SA.« less

Foveal shape and structure in a normal population.

PubMed

Tick, Sarah; Rossant, Florence; Ghorbel, Itebeddine; Gaudric, Alain; Sahel, José-Alain; Chaumet-Riffaud, Philippe; Paques, Michel

2011-07-29

The shape of the human fovea presents important but still poorly characterized variations. In this study, the variability of the shape and structure of normal foveae were examined. In a group of 110 eyes of 57 healthy adults, the shape and structure of the fovea were analyzed by automated segmentation of retinal layer on high-resolution optical coherence tomography scans. In an additional group of 10 normal eyes of 10 patients undergoing fluorescein angiography, the size of the foveal avascular zone (FAZ) was correlated to foveal shape. From the thickest to the thinnest fovea, there was a structural continuum ranging from a shallow pit with continuity of the inner nuclear layer (INL) over the center (seven eyes; 6.7%), to a complete separation of inner layers overlying a flat and thinner central outer nuclear layer (ONL; eight eyes; 7.3%). Central foveal thickness correlated inversely to the degree of inner layer separation and to the surface of the FAZ. Foveal structure strongly correlates with its neurovascular organization. The findings support a developmental model in which the size of the FAZ determines the extent of centrifugal migration of inner retinal layers, which counteracts in some way the centripetal packing of cone photoreceptors.

Calcified cartilage shape in archosaur long bones reflects overlying joint shape in stress-bearing elements: Implications for nonavian dinosaur locomotion.

PubMed

Bonnan, Matthew F; Sandrik, Jennifer L; Nishiwaki, Takahiko; Wilhite, D Ray; Elsey, Ruth M; Vittore, Christopher

2010-12-01

In nonavian dinosaur long bones, the once-living chondroepiphysis (joint surface) overlay a now-fossilized calcified cartilage zone. Although the shape of this zone is used to infer nonavian dinosaur locomotion, it remains unclear how much it reflects chondroepiphysis shape. We tested the hypothesis that calcified cartilage shape reflects the overlying chondroepiphysis in extant archosaurs. Long bones with intact epiphyses from American alligators (Alligator mississippiensis), helmeted guinea fowl (Numida meleagris), and juvenile ostriches (Struthio camelus) were measured and digitized for geometric morphometric (GM) analyses before and after chondroepiphysis removal. Removal of the chondroepiphysis resulted in significant element truncation in all examined taxa, but the amount of truncation decreased with increasing size. GM analyses revealed that Alligator show significant differences between chondroepiphysis shape and the calcified cartilage zone in the humerus, but display nonsignificant differences in femora of large individuals. In Numida, GM analysis shows significant shape differences in juvenile humeri, but humeri of adults and the femora of all guinea fowl show no significant shape difference. The juvenile Struthio sample showed significant differences in both long bones, which diminish with increasing size, a pattern confirmed with magnetic resonance imaging scans in an adult. Our data suggest that differences in extant archosaur long bone shape are greater in elements not utilized in locomotion and related stress-inducing activities. Based on our data, we propose tentative ranges of error for nonavian dinosaur long bone dimensional measurements. We also predict that calcified cartilage shape in adult, stress-bearing nonavian dinosaur long bones grossly reflects chondroepiphysis shape.

Sonochemical synthesis of silica particles and their size control

NASA Astrophysics Data System (ADS)

Kim, Hwa-Min; Lee, Chang-Hyun; Kim, Bonghwan

2016-09-01

Using an ultrasound-assisted sol-gel method, we successfully synthesized very uniformly shaped, monodisperse, and size-controlled spherical silica particles from a mixture of ethanol, water, and tetraethyl orthosilicate in the presence of ammonia as catalyst, at room temperature. The diameters of the silica particles were distributed in the range from 40 to 400 nm; their morphology was well characterized by scanning electron microscopy. The silica particle size could be adjusted by choosing suitable concentrations of ammonium hydroxide and water, which in turn determined the nucleation and growth rates of the particles during the reaction. This sonochemical-based silica synthesis offers an alternative way to produce spherical silica particles in a relatively short reaction time. Thus, we suggest that this simple, low-cost, and efficient method of preparing uniform silica particles of various sizes will have practical and wide-ranging industrial applicability.

Size and habit evolution of PETN crystals - a lattice Monte Carlo study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zepeda-Ruiz, L A; Maiti, A; Gee, R

2006-02-28

Starting from an accurate inter-atomic potential we develop a simple scheme of generating an ''on-lattice'' molecular potential of short range, which is then incorporated into a lattice Monte Carlo code for simulating size and shape evolution of nanocrystallites. As a specific example, we test such a procedure on the morphological evolution of a molecular crystal of interest to us, e.g., Pentaerythritol Tetranitrate, or PETN, and obtain realistic facetted structures in excellent agreement with experimental morphologies. We investigate several interesting effects including, the evolution of the initial shape of a ''seed'' to an equilibrium configuration, and the variation of growth morphologymore » as a function of the rate of particle addition relative to diffusion.« less

Fracture surface analysis of a quenched (α+β)-metastable titanium alloy

NASA Astrophysics Data System (ADS)

Illarionov, A. G.; Stepanov, S. I.; Demakov, S. L.

2017-12-01

Fracture surface analysis is conducted by means of SEM for VT16 titanium alloy specimens solution-treated at temperatures ranging from 700 to 875 °C, water-quenched and subjected to tensile testing. A cup and cone shape failure and dimple microstructure of the fracture surface indicates the ductile behavior of the alloy. Dimple dimensions correlated with the β-grain size of the alloy in quenched condition. The fracture area (namely, the size; the cup and cone shape) depends on the volume fraction of the primary α-phase in the quenched sample. However, the fracture surface changes considerably when the strain-induced β-αʺ-transformation takes place during tensile testing, resulting in the increase of alloy ductility.

Differentiating gold nanorod samples using particle size and shape distributions from transmission electron microscope images

NASA Astrophysics Data System (ADS)

Grulke, Eric A.; Wu, Xiaochun; Ji, Yinglu; Buhr, Egbert; Yamamoto, Kazuhiro; Song, Nam Woong; Stefaniak, Aleksandr B.; Schwegler-Berry, Diane; Burchett, Woodrow W.; Lambert, Joshua; Stromberg, Arnold J.

2018-04-01

Size and shape distributions of gold nanorod samples are critical to their physico-chemical properties, especially their longitudinal surface plasmon resonance. This interlaboratory comparison study developed methods for measuring and evaluating size and shape distributions for gold nanorod samples using transmission electron microscopy (TEM) images. The objective was to determine whether two different samples, which had different performance attributes in their application, were different with respect to their size and/or shape descriptor distributions. Touching particles in the captured images were identified using a ruggedness shape descriptor. Nanorods could be distinguished from nanocubes using an elongational shape descriptor. A non-parametric statistical test showed that cumulative distributions of an elongational shape descriptor, that is, the aspect ratio, were statistically different between the two samples for all laboratories. While the scale parameters of size and shape distributions were similar for both samples, the width parameters of size and shape distributions were statistically different. This protocol fulfills an important need for a standardized approach to measure gold nanorod size and shape distributions for applications in which quantitative measurements and comparisons are important. Furthermore, the validated protocol workflow can be automated, thus providing consistent and rapid measurements of nanorod size and shape distributions for researchers, regulatory agencies, and industry.

The evolution of the avian bill as a thermoregulatory organ.

PubMed

Tattersall, Glenn J; Arnaout, Bassel; Symonds, Matthew R E

2017-08-01

The avian bill is a textbook example of how evolution shapes morphology in response to changing environments. Bills of seed-specialist finches in particular have been the focus of intense study demonstrating how climatic fluctuations acting on food availability drive bill size and shape. The avian bill also plays an important but under-appreciated role in body temperature regulation, and therefore in energetics. Birds are endothermic and rely on numerous mechanisms for balancing internal heat production with biophysical constraints of the environment. The bill is highly vascularised and heat exchange with the environment can vary substantially, ranging from around 2% to as high as 400% of basal heat production in certain species. This heat exchange may impact how birds respond to heat stress, substitute for evaporative water loss at elevated temperatures or environments of altered water availability, or be an energetic liability at low environmental temperatures. As a result, in numerous taxa, there is evidence for a positive association between bill size and environmental temperatures, both within and among species. Therefore, bill size is both developmentally flexible and evolutionarily adaptive in response to temperature. Understanding the evolution of variation in bill size however, requires explanations of all potential mechanisms. The purpose of this review, therefore, is to promote a greater understanding of the role of temperature on shaping bill size over spatial gradients as well as developmental, seasonal, and evolutionary timescales. © 2016 Cambridge Philosophical Society.

Does Print Size Matter for Reading? A Review of Findings from Vision Science and Typography

PubMed Central

Legge, Gordon E.; Bigelow, Charles A.

2012-01-01

The size and shape of printed symbols determine the legibility of text. In this paper we focus on print size because of its crucial role in understanding reading performance and its significance in the history and contemporary practice of typography. We present evidence supporting the hypothesis that the distribution of print sizes in historical and contemporary publications falls within the psychophysically defined range of fluent print size — the range over which text can be read at maximum speed. The fluent range extends over a factor of 10 in angular print size (x-height) from approximately 0.2° to 2°. Assuming a standard reading distance of 40 cm (16 inches), the corresponding physical x-heights are 1.4 mm (4 points) and 14 mm (40 points). We provide new data on the distributions of print sizes in published books and newspapers and in type founders' specimens, and consider factors influencing these distributions. We discuss theoretical concepts from vision science concerning visual size coding that help inform our understanding of historical and modern typographical practices. While economic, social, technological and artistic factors influence type design and selection, we conclude that properties of human visual processing play a dominant role in constraining the distribution of print sizes in common use. PMID:21828237

Does print size matter for reading? A review of findings from vision science and typography.

PubMed

Legge, Gordon E; Bigelow, Charles A

2011-08-09

The size and shape of printed symbols determine the legibility of text. In this paper, we focus on print size because of its crucial role in understanding reading performance and its significance in the history and contemporary practice of typography. We present evidence supporting the hypothesis that the distribution of print sizes in historical and contemporary publications falls within the psychophysically defined range of fluent print size--the range over which text can be read at maximum speed. The fluent range extends over a factor of 10 in angular print size (x-height) from approximately 0.2° to 2°. Assuming a standard reading distance of 40 cm (16 inches), the corresponding physical x-heights are 1.4 mm (4 points) and 14 mm (40 points). We provide new data on the distributions of print sizes in published books and newspapers and in typefounders' specimens, and consider factors influencing these distributions. We discuss theoretical concepts from vision science concerning visual size coding that help inform our understanding of historical and modern typographical practices. While economic, social, technological, and artistic factors influence type design and selection, we conclude that properties of human visual processing play a dominant role in constraining the distribution of print sizes in common use.

A preliminary assessment of asteroid shapes produced by impact disruption and re-creation: Application to the AIDA target.

NASA Astrophysics Data System (ADS)

Barnouin, Olivier; Michel, Patrick; Richardson, Derek

2016-04-01

In order to understand the origin of the 65803 Didymos, the target of the Asteroid Impact and Deflection Assessment mission, and gain insights on the origin and evolution of the asteroid's162173 Ryugu and 101955 Bennu, we investigate systematically the shapes of all re-accumulated fragments produced by the catastrophic disruption of a parent body that is 1 km in diameter or larger. These new fragments eventually become new asteroids of the size that current sample-return missions plan to explore. We choose a range of impact conditions by varying the parent bodies' strength, size and porosity, and the velocity and size of the projectile. Impact conditions range from near the catastrophic threshold, usually designated by Q*, where half of the target's mass escapes, to far greater values above this threshold. Our numerical investigations of the catastrophic disruption, which are undertaken using an SPH hydrocode, include a model of fragmentation for porous materials. The gravitationally dominated phase of reaccumulation of our asteroids is computed using the N-body code pkdgrav. At sufficiently slow impact speeds in the N-body model, particles are permitted to stick, forming irregular, competent pieces that can gather into non-idealized rubble piles as a result of re-accumulation. Shape and spin information of re-accumulated bodies are thus preserved. Due to numerical expense, this first study uses what we call a hard-sphere model, rather than a soft-sphere spring and dashpot model. This latter model is more commonly used in granular flow simulations for which detailed treatment of the multicontact physics is needed, which is not the case here, and comes at the expense of much smaller timesteps. With the hard-sphere model, there are three supported collision outcomes for bonded aggregates: sticking on contact (to grow the aggregate); bouncing (computed for these generally non-central impacts); and fragmentation (wherein the particles involved become detached from their respective aggregates and proceed to bounce as rigid spheres, possibly releasing more particles). We adjusted the strength of the forming aggregates to the measured strength of materials in the lab, scaled to the aggregate size, by using strength size scaling rules. In the future we expect to compare our hard-sphere models to a few soft-sphere for reasonable granular materials to best characterize differences between the two approaches, if any. Our results indicate that while 25143 Itokawa-like potato-shaped asteroids are typically the outcome of disruption, often more spherical or "top-shaped" asteroids can also be produced. Our results confirm what others have already noted, namely that a "top-shaped" or diamond shaped asteroid is not necessarily the result of the formation of YORP spin-up. Other criteria besides just shape need to be developed to determine whether or not the evolution of an asteroid and its surface geology have been dominated by YORP-related processes or by impact-derived re-accretion.

Resonance properties of the biological objects in the RF field

NASA Astrophysics Data System (ADS)

Cocherova, E.; Kupec, P.; Stofanik, V.

2011-12-01

Irradiation of people with electromagnetic fields emitted from miscellaneous devices working in the radio-frequency (RF) range may have influence, for example may affect brain processes. The question of health impact of RF electromagnetic fields on population is still not closed. This article is devoted to an investigation of resonance phenomena of RF field absorption in the models of whole human body and body parts (a head) of different size and shape. The values of specific absorption rate (SAR) are evaluated for models of the different shapes: spherical, cylindrical, realistic shape and for different size of the model, that represents the case of new-born, child and adult person. In the RF frequency region, absorption depends nonlinearly on frequency. Under certain conditions (E-polarization), absorption reaches maximum at frequency, that is called "resonance frequency". The whole body absorption and the resonance frequency depends on many further parameters, that are not comprehensively clarified. The simulation results showed the dependence of the whole-body average SAR and resonance frequency on the body dimensions, as well as the influence of the body shape.

Stem Cells, Patterning and Regeneration in Planarians: Self-Organization at the Organismal Scale.

PubMed

Rink, Jochen C

2018-01-01

The establishment of size and shape remains a fundamental challenge in biological research that planarian flatworms uniquely epitomize. Planarians can regenerate complete and perfectly proportioned animals from tiny and arbitrarily shaped tissue pieces; they continuously renew all organismal cell types from abundant pluripotent stem cells, yet maintain shape and anatomy in the face of constant turnover; they grow when feeding and literally degrow when starving, while scaling form and function over as much as a 40-fold range in body length or an 800-fold change in total cell numbers. This review provides a broad overview of the current understanding of the planarian stem cell system, the mechanisms that pattern the planarian body plan and how the interplay between patterning signals and cell fate choices orchestrates regeneration. What emerges is a conceptual framework for the maintenance and regeneration of the planarian body plan on basis of the interplay between pluripotent stem cells and self-organizing patterns and further, the general utility of planarians as model system for the mechanistic basis of size and shape.

The influence of leaf size and shape on leaf thermal dynamics: does theory hold up under natural conditions?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leigh, A.; Sevanto, Sanna Annika; Close, J. D.

Laboratory studies on artificial leaves suggest that leaf thermal dynamics are strongly influenced by the two-dimensional size and shape of leaves and associated boundary layer thickness. Hot environments are therefore said to favour selection for small, narrow or dissected leaves. Empirical evidence from real leaves under field conditions is scant and traditionally based on point measurements that do not capture spatial variation in heat load. Here in this study, we used thermal imagery under field conditions to measure the leaf thermal time constant (τ) in summer and the leaf-to-air temperature difference (ΔT) and temperature range across laminae (T range) duringmore » winter, autumn and summer for 68 Proteaceae species. We investigated the influence of leaf area and margin complexity relative to effective leaf width (w e), the latter being a more direct indicator of boundary layer thickness. Normalized difference of margin complexity had no or weak effects on thermal dynamics, but w e strongly predicted τ and ΔT, whereas leaf area influenced T range. Unlike artificial leaves, however, spatial temperature distribution in large leaves appeared to be governed largely by structural variation. Therefore, we agree that small size, specifically we, has adaptive value in hot environments but not with the idea that thermal regulation is the primary evolutionary driver of leaf dissection.« less

The influence of leaf size and shape on leaf thermal dynamics: does theory hold up under natural conditions?

DOE PAGES

Leigh, A.; Sevanto, Sanna Annika; Close, J. D.; ...

2016-11-05

Laboratory studies on artificial leaves suggest that leaf thermal dynamics are strongly influenced by the two-dimensional size and shape of leaves and associated boundary layer thickness. Hot environments are therefore said to favour selection for small, narrow or dissected leaves. Empirical evidence from real leaves under field conditions is scant and traditionally based on point measurements that do not capture spatial variation in heat load. Here in this study, we used thermal imagery under field conditions to measure the leaf thermal time constant (τ) in summer and the leaf-to-air temperature difference (ΔT) and temperature range across laminae (T range) duringmore » winter, autumn and summer for 68 Proteaceae species. We investigated the influence of leaf area and margin complexity relative to effective leaf width (w e), the latter being a more direct indicator of boundary layer thickness. Normalized difference of margin complexity had no or weak effects on thermal dynamics, but w e strongly predicted τ and ΔT, whereas leaf area influenced T range. Unlike artificial leaves, however, spatial temperature distribution in large leaves appeared to be governed largely by structural variation. Therefore, we agree that small size, specifically we, has adaptive value in hot environments but not with the idea that thermal regulation is the primary evolutionary driver of leaf dissection.« less

Size and shape of uniform particles precipitated in homogeneous solutions

NASA Astrophysics Data System (ADS)

Sevonkaev, Igor V.

The assembly of nanosize crystals into larger uniform colloids is a fundamental process that plays a critical role in the formation of a very broad range of fine-particles used in numerous applications in technology, medicine, and national security. It is widely accepted that, along with size, in most of these applications the shape of the particles represents a critical factor. In the current research, we investigate the size and shape control of uniform particles prepared by precipitation in homogeneous solutions. In the first---theoretical---part a combinational mechanism of the shape control during particle growth was proposed and analyzed numerically. The main finding of our simulation is that a proper balance of two processes, preferential attachment of transported monomers at the protruding features of the growing cluster and monomer rearrangement at the cluster surface, can yield a well-defined particle shape that persist for sizes much larger than the original seed over a large interval of time. In the experimental part, three chemically simple systems were selected MgF2, NaMgF3, and PbS for defining and evaluating the key parameters of the shape and size control of the precipitates. Thus, uniform dispersions of particles of different morphologies (spherical, cubic, platelet, and prismatic) were prepared by precipitation in aqueous solutions. The mechanisms of the formation of the resulting particles of different shapes are explained by the role of the pH, temperature, solubility, and ionic strength. Stages of particles growth were evaluated on short and long time scales, winch allowed to propose multistage mechanisms of NaMgF3 growth and estimate induction time and critical nuclei size for MgF2. In addition, for prospective numerical modeling the surface tensions of spherical and platelet particles of MgF2 were evaluated from the X-ray data by a lattice parameter change method. Also, a new method for the evaluation of the variation in the density distribution in colloidal spherical particles was proposed. This method utilizes transmission electron microscopy without high resolution mode and processes acquired images. Suggested method eliminates the dependency of the image contrast on sample crystallinity. The advantage of such approach manifested by the short time sample preparation, fast instrument tune-up, rapid image acquisition and analysis, all of which shortens the processing time.

The remarkable convergence of skull shape in crocodilians and toothed whales

PubMed Central

Evans, Alistair R.; Fitzgerald, Erich M. G.; Adams, Justin W.; Clausen, Philip D.; McHenry, Colin R.

2017-01-01

The striking resemblance of long-snouted aquatic mammals and reptiles has long been considered an example of morphological convergence, yet the true cause of this similarity remains untested. We addressed this deficit through three-dimensional morphometric analysis of the full diversity of crocodilian and toothed whale (Odontoceti) skull shapes. Our focus on biomechanically important aspects of shape allowed us to overcome difficulties involved in comparing mammals and reptiles, which have fundamental differences in the number and position of skull bones. We examined whether diet, habitat and prey size correlated with skull shape using phylogenetically informed statistical procedures. Crocodilians and toothed whales have a similar range of skull shapes, varying from extremely short and broad to extremely elongate. This spectrum of shapes represented more of the total variation in our dataset than between phylogenetic groups. The most elongate species (river dolphins and gharials) are extremely convergent in skull shape, clustering outside of the range of the other taxa. Our results suggest the remarkable convergence between long-snouted river dolphins and gharials is driven by diet rather than physical factors intrinsic to riverine environments. Despite diverging approximately 288 million years ago, crocodilians and odontocetes have evolved a remarkably similar morphological solution to feeding on similar prey. PMID:28275142

The remarkable convergence of skull shape in crocodilians and toothed whales.

PubMed

McCurry, Matthew R; Evans, Alistair R; Fitzgerald, Erich M G; Adams, Justin W; Clausen, Philip D; McHenry, Colin R

2017-03-15

The striking resemblance of long-snouted aquatic mammals and reptiles has long been considered an example of morphological convergence, yet the true cause of this similarity remains untested. We addressed this deficit through three-dimensional morphometric analysis of the full diversity of crocodilian and toothed whale (Odontoceti) skull shapes. Our focus on biomechanically important aspects of shape allowed us to overcome difficulties involved in comparing mammals and reptiles, which have fundamental differences in the number and position of skull bones. We examined whether diet, habitat and prey size correlated with skull shape using phylogenetically informed statistical procedures. Crocodilians and toothed whales have a similar range of skull shapes, varying from extremely short and broad to extremely elongate. This spectrum of shapes represented more of the total variation in our dataset than between phylogenetic groups. The most elongate species (river dolphins and gharials) are extremely convergent in skull shape, clustering outside of the range of the other taxa. Our results suggest the remarkable convergence between long-snouted river dolphins and gharials is driven by diet rather than physical factors intrinsic to riverine environments. Despite diverging approximately 288 million years ago, crocodilians and odontocetes have evolved a remarkably similar morphological solution to feeding on similar prey. © 2017 The Author(s).

The drag and terminal velocity of volcanic ash and lapilli with 3D shape obtained by X-ray microtomography

NASA Astrophysics Data System (ADS)

Dioguardi, Fabio; Mele, Daniela; Dellino, Pierfrancesco; Dürig, Tobias

2017-04-01

New experiments of falling volcanic particles were performed in order to define drag and terminal velocity models applicable in a wide range of Reynolds number Re. Experiments were carried out with fluids of various viscosities and with particles that cover a wide range of size, density and shape. Particle shape, which strongly influences fluid drag, was measured in 3D by High-resolution X-ray microtomography, by which sphericity and fractal dimension were obtained, the latter used for quantifying the aerodynamic drag of irregular particles for the first time. With this method, the measure of particle shape descriptors proved to be easier and less operator dependent than previously used 2D image particle analyses. Drag laws that make use of the new 3D parameters were obtained by fitting particle data to the experiments, and single-equation terminal velocity models were derived. They work well both at high and low Re (3x10-2 < Re < 104), while earlier formulations made use of different equations at different ranges of Re. The new drag laws are well suited for the modelling of particle transportation both in the eruptive column and pyroclastic density currents, where coarse and fine particles are present, and also in the distal part of the umbrella region, where fine ash is involved in the large-scale domains of atmospheric circulation. A table of the typical values of 3D sphericity and fractal dimension of particles from known plinian, subplinian and ash plume eruptions is presented. Graphs of terminal velocity as a function of grain size are proposed as tools to help volcanologists and atmosphere scientists to model particle transportation of explosive eruptions. Some volcanological application examples are finally presented.

Morphological and chemical analysis of bone substitutes by scanning electron microscopy and microanalysis by spectroscopy of dispersion energy.

PubMed

da Cruz, Gabriela Alessandra; de Toledo, Sérgio; Sallum, Enilson Antonio; de Lima, Antonio Fernando Martorelli

2007-01-01

This study evaluated the morphological and chemical composition of the following bone substitutes: cancellous and cortical organic bovine bone with macro and microparticle size ranging from 1.0 to 2.0 mm and 0.25 to 1.0 mm, respectively; inorganic bovine bone with particle size ranging from 0.25 to 1.0 mm; hydroxyapatite with particle size ranging from 0.75 to 1.0 mm; and demineralized freeze-dried bone allograft with particle size ranging from 0.25 to 0.5 mm. The samples were sputter-coated with gold in an ion coater, the morphology was observed and particle size was measured under vacuum by scanning electron microscopy (SEM). The chemical composition was evaluated by spectroscopy of dispersion energy (EDS) microanalysis using samples without coating. SEM analysis provided visual evidence that all examined materials have irregular shape and particle sizes larger than those informed by the manufacturer. EDS microanalysis detected the presence of sodium, calcium and phosphorus that are usual elements of the bone tissue. However, mineral elements were detected in all analyzed particles of organic bovine bone except for macro cancellous organic bovine bone. These results suggest that the examined organic bovine bone cannot be considered as a pure organic material.

The interplay of demography and selection during maize domestication and expansion

USDA-ARS?s Scientific Manuscript database

The history of maize has been characterized by major demographic events including changes in population size associated with domestication and subsequent range expansion as well as gene flow with wild relatives. This complex demographic history and its interplay with selection have shaped diversity ...

A UHF RFID system with on-chip-antenna tag for short range communication

NASA Astrophysics Data System (ADS)

Qi, Peng; Chun, Zhang; Xijin, Zhao; Zhihua, Wang

2015-05-01

A UHF RF identification system based on the 0.18 μm CMOS process has been developed for short range and harsh size requirement applications, which is composed of a fully integrated tag and a special reader. The whole tag chip with the antenna takes up an area of 0.36 mm2, which is smaller than other reported tags with an on-chip antenna (OCA) using the standard CMOS process. A self-defined protocol is proposed to reduce the power consumption, and minimize the size of the tag. The specialized SOC reader system consists of the RF transceiver, digital baseband, MCU and host interface. Its power consumption is about 500 mW. Measurement results show that the system's reading range is 2 mm with 20 dBm reader output power. With an inductive antenna printed on a paper substrate around the OCA tag, the reading range can be extended from several centimeters to meters, depending on the shape and size of the inductive antenna.

Growth and relaxation processes in Ge nanocrystals on free-standing Si(001) nanopillars.

PubMed

Kozlowski, G; Zaumseil, P; Schubert, M A; Yamamoto, Y; Bauer, J; Schülli, T U; Tillack, B; Schroeder, T

2012-03-23

We study the growth and relaxation processes of Ge crystals selectively grown by chemical vapour deposition on free-standing 90 nm wide Si(001) nanopillars. Epi-Ge with thickness ranging from 4 to 80 nm was characterized by synchrotron based x-ray diffraction and transmission electron microscopy. We found that the strain in Ge nanostructures is plastically released by nucleation of misfit dislocations, leading to degrees of relaxation ranging from 50 to 100%. The growth of Ge nanocrystals follows the equilibrium crystal shape terminated by low surface energy (001) and {113} facets. Although the volumes of Ge nanocrystals are homogeneous, their shape is not uniform and the crystal quality is limited by volume defects on {111} planes. This is not the case for the Ge/Si nanostructures subjected to thermal treatment. Here, improved structure quality together with high levels of uniformity of the size and shape is observed.

Volumes and bulk densities of forty asteroids from ADAM shape modeling

NASA Astrophysics Data System (ADS)

Hanuš, J.; Viikinkoski, M.; Marchis, F.; Ďurech, J.; Kaasalainen, M.; Delbo', M.; Herald, D.; Frappa, E.; Hayamizu, T.; Kerr, S.; Preston, S.; Timerson, B.; Dunham, D.; Talbot, J.

2017-05-01

Context. Disk-integrated photometric data of asteroids do not contain accurate information on shape details or size scale. Additional data such as disk-resolved images or stellar occultation measurements further constrain asteroid shapes and allow size estimates. Aims: We aim to use all the available disk-resolved images of approximately forty asteroids obtained by the Near-InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope together with the disk-integrated photometry and stellar occultation measurements to determine their volumes. We can then use the volume, in combination with the known mass, to derive the bulk density. Methods: We downloaded and processed all the asteroid disk-resolved images obtained by the Nirc2 that are available in the Keck Observatory Archive (KOA). We combined optical disk-integrated data and stellar occultation profiles with the disk-resolved images and use the All-Data Asteroid Modeling (ADAM) algorithm for the shape and size modeling. Our approach provides constraints on the expected uncertainty in the volume and size as well. Results: We present shape models and volume for 41 asteroids. For 35 of these asteroids, the knowledge of their mass estimates from the literature allowed us to derive their bulk densities. We see a clear trend of lower bulk densities for primitive objects (C-complex) and higher bulk densities for S-complex asteroids. The range of densities in the X-complex is large, suggesting various compositions. We also identified a few objects with rather peculiar bulk densities, which is likely a hint of their poor mass estimates. Asteroid masses determined from the Gaia astrometric observations should further refine most of the density estimates.

78 FR 74154 - Draft Guidance for Industry on Size, Shape, and Other Physical Attributes of Generic Tablets and...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-10

...] Draft Guidance for Industry on Size, Shape, and Other Physical Attributes of Generic Tablets and... ``Size, Shape, and Other Physical Attributes of Generic Tablets and Capsules.'' This guidance discusses FDA recommendations for the size, shape, and other physical attributes of generic tablets intended to...

Smaller beaks for colder winters: Thermoregulation drives beak size evolution in Australasian songbirds.

PubMed

Friedman, Nicholas R; Harmáčková, Lenka; Economo, Evan P; Remeš, Vladimír

2017-08-01

Birds' beaks play a key role in foraging, and most research on their size and shape has focused on this function. Recent findings suggest that beaks may also be important for thermoregulation, and this may drive morphological evolution as predicted by Allen's rule. However, the role of thermoregulation in the evolution of beak size across species remains largely unexplored. In particular, it remains unclear whether the need for retaining heat in the winter or dissipating heat in the summer plays the greater role in selection for beak size. Comparative studies are needed to evaluate the relative importance of these functions in beak size evolution. We addressed this question in a clade of birds exhibiting wide variation in their climatic niche: the Australasian honeyeaters and allies (Meliphagoidea). Across 158 species, we compared species' climatic conditions extracted from their ranges to beak size measurements in a combined spatial-phylogenetic framework. We found that winter minimum temperature was positively correlated with beak size, while summer maximum temperature was not. This suggests that while diet and foraging behavior may drive evolutionary changes in beak shape, changes in beak size can also be explained by the beak's role in thermoregulation, and winter heat retention in particular. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Dynamic modeling of photothermal interactions for laser-induced interstitial thermotherapy: parameter sensitivity analysis.

PubMed

Jiang, S C; Zhang, X X

2005-12-01

A two-dimensional model was developed to model the effects of dynamic changes in the physical properties on tissue temperature and damage to simulate laser-induced interstitial thermotherapy (LITT) treatment procedures with temperature monitoring. A modified Monte Carlo method was used to simulate photon transport in the tissue in the non-uniform optical property field with the finite volume method used to solve the Pennes bioheat equation to calculate the temperature distribution and the Arrhenius equation used to predict the thermal damage extent. The laser light transport and the heat transfer as well as the damage accumulation were calculated iteratively at each time step. The influences of different laser sources, different applicator sizes, and different irradiation modes on the final damage volume were analyzed to optimize the LITT treatment. The numerical results showed that damage volume was the smallest for the 1,064-nm laser, with much larger, similar damage volumes for the 980- and 850-nm lasers at normal blood perfusion rates. The damage volume was the largest for the 1,064-nm laser with significantly smaller, similar damage volumes for the 980- and 850-nm lasers with temporally interrupted blood perfusion. The numerical results also showed that the variations in applicator sizes, laser powers, heating durations and temperature monitoring ranges significantly affected the shapes and sizes of the thermal damage zones. The shapes and sizes of the thermal damage zones can be optimized by selecting different applicator sizes, laser powers, heating duration times, temperature monitoring ranges, etc.

Interaction location outweighs the competitive advantage of numerical superiority in Cebus capucinus intergroup contests

PubMed Central

Crofoot, Margaret C.; Gilby, Ian C.; Wikelski, Martin C.; Kays, Roland W.

2008-01-01

Numerical superiority confers a competitive advantage during contests among animal groups, shaping patterns of resource access, and, by extension, fitness. However, relative group size does not always determine the winner of intergroup contests. Smaller, presumably weaker social groups often defeat their larger neighbors, but how and when they are able to do so remains poorly understood. Models of competition between individuals suggest that location may influence contest outcome. However, because of the logistical difficulties of studying intergroup interactions, previous studies have been unable to determine how contest location and group size interact to shape relationships among groups. We address this question by using an automated radio telemetry system to study intergroup interactions among six capuchin monkey (Cebus capucinus) social groups of varying sizes. We find that the odds of winning increase with relative group size; one additional group member increases the odds of winning an interaction by 10%. However, this effect is not uniform across space; with each 100 m that a group moves away from the center of its home range, its odds of winning an interaction decrease by 31%. We demonstrate that contest outcome depends on an interaction between group size and location, such that small groups can defeat much larger groups near the center of their home range. The tendency of resident groups to win contests may help explain how small groups persist in areas with intense intergroup competition. PMID:18184811

Suggested design of gold-nanoobjects-based terahertz radiation source for biomedical research

NASA Astrophysics Data System (ADS)

Postnikov, A. V.; Moldosanov, K. A.

2018-07-01

Gold nanoparticles (GNPs) may serve as devices to emit electromagnetic radiation in the terahertz (THz) range, whereby the energy is delivered by radio frequency or microwave photons which will not by themselves induce transitions between sparse confinement-shaped electron levels of a GNP, but may borrow the energy from longitudinal acoustic (LA) phonons to overcome the confinement gap. Upon excitation, the Fermi electron cannot relax otherwise than via emitting a THz photon, the other relaxation channels being blocked by force of shape and size considerations. Within this general scope that has already been outlined earlier, the present work specifically discusses two-phonon processes, namely (i) a combined absorption–emission of two phonons from the top of the LA branch, and (ii) an absorption of two such phonons with nearly identical wavevectors. The case (i) may serve as a source of soft THz radiation (at ≃0.54 THz), the case (ii) the hard THz radiation at 8.7 THz. Numerical estimates are done for crystalline particles in the shape of rhombicuboctahedra, of 5–7 nm size. A technical realisation of this idea is briefly discussed, assuming the deposition of GNPs onto/within the substrate of Teflon®, the material sustaining high temperatures and transparent in the THz range.

Suggested design of gold-nanoobjects-based terahertz radiation source for biomedical research.

PubMed

Postnikov, A V; Moldosanov, K A

2018-04-18

Gold nanoparticles (GNPs) may serve as devices to emit electromagnetic radiation in the terahertz (THz) range, whereby the energy is delivered by radio frequency or microwave photons which will not by themselves induce transitions between sparse confinement-shaped electron levels of a GNP, but may borrow the energy from longitudinal acoustic (LA) phonons to overcome the confinement gap. Upon excitation, the Fermi electron cannot relax otherwise than via emitting a THz photon, the other relaxation channels being blocked by force of shape and size considerations. Within this general scope that has already been outlined earlier, the present work specifically discusses two-phonon processes, namely (i) a combined absorption-emission of two phonons from the top of the LA branch, and (ii) an absorption of two such phonons with nearly identical wavevectors. The case (i) may serve as a source of soft THz radiation (at ≃0.54 THz), the case (ii) the hard THz radiation at 8.7 THz. Numerical estimates are done for crystalline particles in the shape of rhombicuboctahedra, of 5-7 nm size. A technical realisation of this idea is briefly discussed, assuming the deposition of GNPs onto/within the substrate of Teflon ® , the material sustaining high temperatures and transparent in the THz range.

Illustrating ontogenetic change in the dentition of the Nile monitor lizard, Varanus niloticus: a case study in the application of geometric morphometric methods for the quantification of shape–size heterodonty

PubMed Central

D'Amore, Domenic C

2015-01-01

Many recent attempts have been made to quantify heterodonty in non-mammalian vertebrates, but the majority of these are limited to Euclidian measurements. One taxon frequently investigated is Varanus niloticus, the Nile monitor. Juveniles possess elongate, pointed teeth (caniniform) along the entirety of the dental arcade, whereas adults develop large, bulbous distal teeth (molariform). The purpose of this study was to present a geometric morphometric method to quantify V. niloticus heterodonty through ontogeny that may be applied to other non-mammalian taxa. Data were collected from the entire tooth row of 19 dry skull specimens. A semilandmark analysis was conducted on the outline of the photographed teeth, and size and shape were derived. Width was also measured with calipers. From these measures, sample ranges and allometric functions were created using multivariate statistical analyses for each tooth position separately, as well as overall measures of heterodonty for each specimen based on morphological disparity. The results confirm and expand upon previous studies, showing measurable shape–size heterodonty in the species with significant differences at each tooth position. Tooth size increases with body size at most positions, and the allometric coefficient increases at more distal positions. Width shows a dramatic increase at the distal positions with ontogeny, often displaying pronounced positive allometry. Dental shape varied in two noticeable ways, with the first composing the vast majority of shape variance: (i) caniniformy vs. molariformy and (ii) mesially leaning, ‘rounded’ apices vs. distally leaning, ‘pointed’ apices. The latter was twice as influential in the mandible, a consequence of host bone shape. Mesial teeth show no significant shape change with growth, whereas distal teeth change significantly due primarily to an increase in molariformy. Overall, heterodonty increases with body size concerning both tooth size and shape, but shape heterodonty changes in the mandible are much less pronounced. Although it is unclear to what degree V. niloticus specializes in hard prey items (durophagy), previous studies of varanid feeding behavior, along with research on analogous durophagous vertebrates, indicate a division of labor along the tooth row in adults, due to a possible transition to at least a partial durophagous niche. The geometric morphometric method proposed here, although not without its own limitations, may be ideal for use with a number of dental morphotypes in the future. PMID:25939576

A National Census of Birth Weight in Purebred Dogs in Italy

PubMed Central

Groppetti, Debora; Pecile, Alessandro; Palestrini, Clara; Marelli, Stefano P.; Boracchi, Patrizia

2017-01-01

Simple Summary Birth weight is a key factor for neonatal mortality and morbidity in most mammalian species. The great morphological variability in size, body weight and breed, as well as in skeletal and cranial conformation makes it challenging to define birth weight standards in dogs. A total of 3293 purebred pups were surveyed to study which maternal aspects can determine birth weight considering head and body shape, size, body weight and breed in bitches, as well as litter size and sex in pups. In our sample, multivariate analysis outcomes suggested that birth weight and litter size were directly proportional to maternal size. The maternal body shape influenced both birth weight and litter size, whereas the maternal head shape had impact only on birth weight. Sex differences in birth weight were found. Birth weight and litter size also varied among breeds. The results of the present study could have practical implications allowing one to identify pups in need of admission to intensive nursing care, as occurs in humans. A deeper knowledge of the factors that significantly influence birth weight could positively affect the canine breeding management helping to prevent and reduce neonatal mortality. Abstract Despite increasing professionalism in dog breeding, the physiological range of birth weight in this species remains unclear. Low birth weight can predispose to neonatal mortality and growth deficiencies in humans. To date, the influence of the morphotype on birth weight has never been studied in dogs. For this purpose, an Italian census of birth weight was collected from 3293 purebred pups based on maternal morphotype, size, body weight and breed, as well as on litter size and sex of pups. Multivariate analysis outcomes showed that birth weight (p < 0.001) and litter size (p < 0.05) increased with maternal size and body weight. Birth weight was also influenced by the maternal head and body shape, with brachycephalic and brachymorph dogs showing the heaviest and the lightest pups, respectively (p < 0.001). Birth weight decreased with litter size (p < 0.001), and male pups were heavier than females (p < 0.001). These results suggest that canine morphotype, not only maternal size and body weight, can affect birth weight and litter size with possible practical implications in neonatal assistance. PMID:28556821

Stony Endocarp Dimension and Shape Variation in Prunus Section Prunus

PubMed Central

Depypere, Leander; Chaerle, Peter; Mijnsbrugge, Kristine Vander; Goetghebeur, Paul

2007-01-01

Background and Aims Identification of Prunus groups at subspecies or variety level is complicated by the wide range of variation and morphological transitional states. Knowledge of the degree of variability within and between species is a sine qua non for taxonomists. Here, a detailed study of endocarp dimension and shape variation for taxa of Prunus section Prunus is presented. Method The sample size necessary to obtain an estimation of the population mean with a precision of 5 % was determined by iteration. Two cases were considered: (1) the population represents an individual; and (2) the population represents a species. The intra-individual and intraspecific variation of Prunus endocarps was studied by analysing the coefficients of variance for dimension and shape parameters. Morphological variation among taxa was assessed using univariate statistics. The influence of the time of sampling and the level of hydration on endocarp dimensions and shape was examined by means of pairwise t-tests. In total, 14 endocarp characters were examined for five Eurasian plum taxa. Key Results All linear measurements and index values showed a low or normal variability on the individual and species level. In contrast, the parameter ‘Vertical Asymmetry’ had high coefficients of variance for one or more of the taxa studied. Of all dimension and shape parameters studied, only ‘Triangle’ differed significantly between mature endocarps of P. insititia sampled with a time difference of 1 month. The level of hydration affected endocarp dimensions and shape significantly. Conclusions Index values and the parameters ‘Perimeter’, ‘Area’, ‘Triangle’, ‘Ellipse’, ‘Circular’ and ‘Rectangular’, based on sample sizes and coefficients of variance, were found to be most appropriate for further taxonomic analysis. However, use of one, single endocarp parameter is not satisfactory for discrimination between Eurasian plum taxa, mainly because of overlapping ranges. Before analysing dried endocarps, full hydration is recommended, as this restores the original dimensions and shape. PMID:17965026

Calculations of the variability of ice cloud radiative properties at selected solar wavelengths

NASA Technical Reports Server (NTRS)

Welch, R. M.; Zdunkowski, W. G.; Cox, S. K.

1980-01-01

This study shows that there is surprising little difference in values of reflectance, absorptance, and transmittance for many of the intermediate-size particle spectra. Particle size distributions with mode radii ranging from approximately 50 to 300 microns, irrespective of particle shape and nearly independent of the choice of size distribution representation, give relatively similar flux values. The very small particle sizes, however, have significantly larger values of reflectance and transmittance with corresponding smaller values of absorptance than do the larger particle sizes. The very large particle modes produce very small values of reflectance and transmittance along with very large values of absorptance. Such variations are particularly noticeable when plotted as a function of wavelength.

Fungal synthesis of size-defined nanoparticles

NASA Astrophysics Data System (ADS)

Zielonka, Aleksandra; Klimek-Ochab, Magdalena

2017-12-01

Fungi with metabolic capacities can efficiently synthesize a wide range of nanoparticles (NPs). This biotransformation process and its product have extensive applications especially for industry, agriculture and medicine, where NPs size and shape is essential and can be defined by specific analytical methods. Fungi cultivation and further bioconversion can be fully controlled to obtain the desired nanoparticles. Additionally, this review provides information about the fungus F. oxysporum, which is able to synthesize the largest amount of different types of NPs.

Gardening with Greenhouses

ERIC Educational Resources Information Center

Keeler, Rusty

2010-01-01

Greenhouses come in all shapes, sizes, and price ranges: from simple hand-built plastic-covered frames to dazzling geodesic domes. Some child care centers install greenhouses as a part of their outdoor garden space. Other centers have incorporated a greenhouse into the building itself. Greenhouses provide a great opportunity for children to grow…

Thermal conductivity measurements of particulate materials under Martian conditions

NASA Technical Reports Server (NTRS)

Presley, M. A.; Christensen, P. R.

1993-01-01

The mean particle diameter of surficial units on Mars has been approximated by applying thermal inertia determinations from the Mariner 9 Infrared Radiometer and the Viking Infrared Thermal Mapper data together with thermal conductivity measurement. Several studies have used this approximation to characterize surficial units and infer their nature and possible origin. Such interpretations are possible because previous measurements of the thermal conductivity of particulate materials have shown that particle size significantly affects thermal conductivity under martian atmospheric pressures. The transfer of thermal energy due to collisions of gas molecules is the predominant mechanism of thermal conductivity in porous systems for gas pressures above about 0.01 torr. At martian atmospheric pressures the mean free path of the gas molecules becomes greater than the effective distance over which conduction takes place between the particles. Gas particles are then more likely to collide with the solid particles than they are with each other. The average heat transfer distance between particles, which is related to particle size, shape and packing, thus determines how fast heat will flow through a particulate material.The derived one-to-one correspondence of thermal inertia to mean particle diameter implies a certain homogeneity in the materials analyzed. Yet the samples used were often characterized by fairly wide ranges of particle sizes with little information about the possible distribution of sizes within those ranges. Interpretation of thermal inertia data is further limited by the lack of data on other effects on the interparticle spacing relative to particle size, such as particle shape, bimodal or polymodal mixtures of grain sizes and formation of salt cements between grains. To address these limitations and to provide a more comprehensive set of thermal conductivities vs. particle size a linear heat source apparatus, similar to that of Cremers, was assembled to provide a means of measuring the thermal conductivity of particulate samples. In order to concentrate on the dependence of the thermal conductivity on particle size, initial runs will use spherical glass beads that are precision sieved into relatively small size ranges and thoroughly washed.

Characterisation of Fine Ash Fractions from the AD 1314 Kaharoa Eruption

NASA Astrophysics Data System (ADS)

Weaver, S. J.; Rust, A.; Carey, R. J.; Houghton, B. F.

2012-12-01

The AD 1314±12 yr Kaharoa eruption of Tarawera volcano, New Zealand, produced deposits exhibiting both plinian and subplinian characteristics (Nairn et al., 2001; 2004, Leonard et al., 2002, Hogg et al., 2003). Their widespread dispersal yielded volumes, column heights, and mass discharge rates of plinian magnitude and intensity (Sahetapy-Engel, 2002); however, vertical shifts in grain size suggest waxing and waning within single phases and time-breaks on the order of hours between phases. These grain size shifts were quantified using sieve, laser diffraction, and image analysis of the fine ash fractions (<1 mm in diameter) of some of the most explosive phases of the eruption. These analyses served two purposes: 1) to characterise the change in eruption intensity over time, and 2) to compare the three methods of grain size analysis. Additional analyses of the proportions of components and particle shape were also conducted to aid in the interpretation of the eruption and transport dynamics. 110 samples from a single location about 6 km from source were sieved at half phi intervals between -4φ to 4φ (16 mm - 63 μm). A single sample was then chosen to test the range of grain sizes to run through the Mastersizer 2000. Three aliquots were tested; the first consisted of each sieve size fraction ranging between 0φ (1000 μm) and <4φ (<63 μm, i.e. the pan). For example, 0, 0.5, 1, …, 4φ, and the pan were ran through the Mastersizer and then their results, weighted according to their sieve weight percents, were summed together to produce a total distribution. The second aliquot included 3 samples ranging between 0-2φ (1000-250 μm), 2.5-4φ (249-63 μm), and the pan. A single sample consisting of the total range of grain sizes between 0φ and the pan was used for the final aliquot. Their results were compared and it was determined that the single sample consisting of the broadest range of grain sizes yielded an accurate grain size distribution. This data was then compared with the sieve weight percent data, and revealed that there is a significant difference in size characterisation between sieving and the Mastersizer for size fractions between 0-3φ (1000-125 μm). This is due predominantly to the differing methods that sieving and the Mastersizer use to characterise a single particle, to inhomogeneity in grain density in each grain-size fraction, and to grain-shape irregularities. This led the Mastersizer to allocate grains from a certain sieve size fraction into coarser size fractions. Therefore, only the Mastersizer data from 3.5φ and below were combined with the coarser sieve data to yield total grain size distributions. This high-resolution analysis of the grain size data enabled subtle trends in grain size to be identified and related to short timescale eruptive processes.

Noctilucent cloud polarimetry: Twilight measurements in a wide range of scattering angles

NASA Astrophysics Data System (ADS)

Ugolnikov, Oleg S.; Maslov, Igor A.; Kozelov, Boris V.; Dlugach, Janna M.

2016-06-01

Wide-field polarization measurements of the twilight sky background during several nights with bright and extended noctilucent clouds in central and northern Russia in 2014 and 2015 are used to build the phase dependence of the degree of polarization of sunlight scattered by cloud particles in a wide range of scattering angles (from 40° to 130°). This range covers the linear polarization maximum near 90° and large-angle slope of the curve. The polarization in this angle range is most sensitive to the particle size. The method of separation of scattering on cloud particles from the twilight background is presented. Results are compared with T-matrix simulations for different sizes and shapes of ice particles; the best-fit model radius of particles (0.06 μm) and maximum radius (about 0.1 μm) are estimated.

Nanoparticle heterodimers: The role of size and interparticle gap distance on the optical response

NASA Astrophysics Data System (ADS)

Mokkath, Junais Habeeb

2018-05-01

Composite plasmonic nanostructures with controlled size, shape and relative arrangement is a subject of significant current research interest. Much of this is stimulated by the prospects by generating enormous near-field enhancements of the surface and interparticle gap regions for potential applications in surface-enhanced spectroscopies. In this manuscript, using time-dependent density functional theory (TDDFT) calculations, we investigate how the optical response in size matched homodimers and size mismatched heterodimers composed of Aluminum modify while varying the size and interparticle gap distances in the sub-nanometer range. Both systems show interesting optical response evolution. In particular, the size mismatched heterodimers show even more complex optical response evolution due to a symmetry-breaking in the system.

Microstructure and Shape Memory Characteristics of Powder-Metallurgical-Processed Ti-Ni-Cu Alloys

NASA Astrophysics Data System (ADS)

Kim, Yeon-Wook; Chung, Young-Soo; Choi, Eunsoo; Nam, Tae-Hyun

2012-08-01

Even though Ti-Ni-Cu alloys have attracted a lot of attention because of their high performance in shape memory effect and decrease in thermal and stress hysteresis compared with Ti-Ni binary alloys, their poor workability restrains the practical applications of Ti-Ni-Cu shape memory alloys. Consolidation of Ti-Ni-Cu alloy powders is useful for the fabrication of bulk near-net-shape shape memory alloy. Ti50Ni30Cu20 shape memory alloy powders were prepared by gas atomization, and the sieved powders with the specific size range of 25 to 150 μm were chosen for this study. The evaluation of powder microstructures was based on a scanning electron microscope (SEM) examination of the surface and the polished and etched powder cross sections. The typical images showed cellular/dendrite morphology and high population of small shrinkage cavities at intercellular regions. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis showed that a B2-B19 one-step martensitic transformation occurred in the as-atomized powders. The martensitic transformation start temperature (Ms) of powders ranging between 25 and 50 μm was 304.5 K (31.5 °C). The Ms increased with increasing powder size. However, the difference of Ms in the as-atomized powders ranging between 25 and 150 μm was only 274 K (1 °C). A dense cylindrical specimen of 10 mm diameter and 15 mm length were fabricated by spark plasma sintering (SPS) at 1073 K (800 °C) and 10 MPa for 20 minutes. Then, this bulk specimen was heat treated for 60 minutes at 1123 K (850 °C) and quenched in ice water. The Ms of the SPS specimen was 310.5 K (37.5 °C) whereas the Ms of conventionally cast ingot is found to be as high as 352.7 K (79.7 °C). It is considered that the depression of the Ms in rapidly solidified powders is ascribed to the density of dislocations and the stored energy produced by rapid solidification.

Analysis of the interplay among charge, hydration and shape of proteins through the modeling of their CZE mobility data.

PubMed

Piaggio, Maria V; Peirotti, Marta B; Deiber, Julio A

2009-07-01

Electrophoretic mobility data of four proteins are analyzed and interpreted through a physicochemical CZE model, which provides estimates of quantities like equivalent hydrodynamic radius (size), effective charge number, shape orientation factor, hydration, actual pK values of ionizing groups, and pH near molecule, among others. Protein friction coefficients are simulated through the creeping flow theory of prolate spheroidal particles. The modeling of the effective electrophoretic mobility of proteins requires consideration of hydrodynamic size and shape coupled to hydration and effective charge. The model proposed predicts native protein hydration within the range of values obtained experimentally from other techniques. Therefore, this model provides consistently other physicochemical properties such as average friction and diffusion coefficients and packing fractal dimension. As the pH varies from native conditions to those that are denaturing the protein, hydration and packing fractal dimension change substantially. Needs for further research are also discussed and proposed.

Plasmon-shaped polarization gating for high-order-harmonic generation

NASA Astrophysics Data System (ADS)

Wang, Feng; He, Lixin; Chen, Jiawei; Wang, Baoning; Zhu, Xiaosong; Lan, Pengfei; Lu, Peixiang

2017-12-01

We present a plasmon-shaped polarization gating for high-order-harmonic generation by using a linearly polarized laser field to illuminate two orthogonal bow-tie nanostructures. The results show that when these two bow-tie nanostructures have nonidentical geometrical sizes, the transverse and longitudinal components of the incident laser field will experience different phase responses, thus leading to a time-dependent ellipticity of laser field. For the polarizing angle of incident laser field in the range from 45∘ to 60∘, the dominant harmonic emission is gated within the few optical cycles where the laser ellipticity is below 0.3. Then sub-50-as isolated attosecond pulses (IAPs) can be generated. Such a plasmon-shaped polarization gating is robust for IAP generation against the variations of the carrier-envelope phases of the laser pulse. Moreover, by changing the geometrical size of one of the bow-tie nanostructures, the electron dynamics can be effectively controlled and the more efficient supercontinuum as well as IAP can be generated.

Finite-sized one-dimensional silica microstructures (rods): Synthesis, assembly, and applications

DOE PAGES

Sharma, Jaswinder

2017-01-28

Colloidal silica structures are highly important for applications ranging from surface modifications such as superhydrophobic, oleophobic, icephobic, and anti-biofouling coatings, as reinforcements in polymer-ceramic or metal-matrix composites, and phonon management. In addition to various types of silica structures, a unique structure silica rods has been synthesized by employing the emulsion droplets made by dissolving polyvinlypyrrolidone in pentanol. While a significant progress has been made in further modifying their shape and chemistry, in their assembly, and in their applications, however, no review article compiled the progress in this field. Furthermore, this minireview intends to highlight the development in the synthesis, assembly,more » and application of these rods, and discuss the remaining challenges for precise control of size and shape, possible solutions, and potential applications.« less

Technologies for precision manufacture of current and future windows and domes

NASA Astrophysics Data System (ADS)

Hallock, Bob; Shorey, Aric

2009-05-01

The final finish and characterization of windows and domes presents a number of challenges in achieving desired precision with acceptable cost and schedule. This becomes more difficult with advanced materials and as window and dome shapes and requirements become more complex, including acute angle corners, transmitted wavefront specifications, aspheric geometries and trending toward conformal surfaces. Magnetorheological Finishing (MRF®) and Magnetorheological Jet (MR Jet®), along with metrology provided by Sub-aperture Stitching Interferometry (SSI®) have several unique attributes that provide them advantages in enhancing fabrication of current and next generation windows and domes. The advantages that MRF brings to the precision finishing of a wide range of shapes such as flats, spheres (including hemispheres), cylinders, aspheres and even freeform optics, has been well documented. Recent advancements include the ability to finish freeform shapes up to 2-meters in size as well as progress in finishing challenging IR materials. Due to its shear-based removal mechanism in contrast to the pressure-based process of other techniques, edges are not typically rolled, in particular on parts with acute angle corners. MR Jet provides additional benefits, particularly in the finishing of the inside of steep concave domes and other irregular shapes. The ability of MR Jet to correct the figure of conformal domes deterministically and to high precision has been demonstrated. Combining these technologies with metrology techniques, such as SSI provides a solution for finishing current and future windows and domes in a reliable, deterministic and cost-effective way. The ability to use the SSI to characterize a range of shapes such as domes and aspheres, as well as progress in using MRF and MR Jet for finishing conventional and conformal windows and domes with increasing size and complexity of design will be presented.

Thermal phonon transport in Si thin film with dog-leg shaped asymmetric nanostructures

NASA Astrophysics Data System (ADS)

Kage, Yuta; Hagino, Harutoshi; Yanagisawa, Ryoto; Maire, Jeremie; Miyazaki, Koji; Nomura, Masahiro

2016-08-01

Thermal phonon transport in single-crystalline Si thin films with dog-leg shaped nanostructures was investigated. Thermal conductivities for the forward and backward directions were measured and compared at 5 and 295 K by micro thermoreflectance. The Si thin film with dog-leg shaped nanostructures showed lower thermal conductivities than those of nanowires and two-dimensional phononic crystals with circular holes at the same surface-to-volume ratio. However, asymmetric thermal conductivity was not observed at small temperature gradient condition in spite of the highly asymmetric shape though the size of the pattern is within thermal phonon mean free path range. We conclude that strong temperature dependent thermal conductivity is required to observe the asymmetric thermal phonon conduction in monolithic materials with asymmetric nanostructures.

Phase-field study on geometry-dependent migration behavior of voids under temperature gradient in UO2 crystal matrix

NASA Astrophysics Data System (ADS)

Chen, Weijin; Peng, Yuyi; Li, Xu'an; Chen, Kelang; Ma, Jun; Wei, Lingfeng; Wang, Biao; Zheng, Yue

2017-10-01

In this work, a phase-field model is established to capture the void migration behavior under a temperature gradient within a crystal matrix, with an appropriate consideration of the surface diffusion mechanism and the vapor transport mechanism. The interfacial energy and the coupling between the vacancy concentration field and the crystal order parameter field are carefully modeled. Simulations are performed on UO2. The result shows that for small voids (with an area ≤ πμm2), the well-known characteristics of void migration, in consistence with the analytical model, can be recovered. The migration is manifested by a constant velocity and a minor change of the void shape. In contrast, for large voids (with an area of ˜10 μm2) initially in circular shapes, significant deformation of the void from a circular to cashew-like shape is observed. After long-time migration, the deformed void would split into smaller voids. The size-dependent behavior of void migration is due to the combined effect of the interfacial energy (which tends to keep the void in circular shape) and the surface diffusion flow (which tends to deform the void due to the nonuniform diffusion along the surface). Moreover, the initial shape of the void modifies the migration velocity and the time point when splitting occurs (for large voids) at the beginning of migration due to the shape relaxation of the void. However, it has a minor effect on the long-time migration. Our work reveals novel void migration behaviors in conditions where the surface-diffusion mechanism is dominant over the vapor transport mechanism; meanwhile, the size of the void lies at a mediate size range.

Complex pattern of variation in neurocranial ontogeny revealed by CT-scanning.

PubMed

Anzelmo, Marisol; Ventrice, Fernando; Kelmansky, Diana; Sardi, Marina

2018-05-01

The neurocranium of hominid species has been largely studied with reference to the midsagittal plane, with variations being attributed to brain evolution. By contrast, there is limited information on variation in non-midsagittal regions, which are the points of insertion of muscles and bony structures related to mastication. This work aims to analyze ontogenetic changes and sexual dimorphism (SD) in midsagittal and non-midsagittal neurocranial structures from a contemporary human sample comprising 138 computed tomography (CT) cranial images of individuals ranging from infants to adults. Morphology of the vault and the base was assessed by registering landmarks and semilandmarks, which were analyzed by geometric morphometrics, and the endocranial volume (EV). The results of regressions and Kruskal-Wallis test indicate that the major size and shape changes in both midsagittal and non-midsagittal regions occur during infancy and juvenility; shape changes are also associated with an increase in EV. The size of the midsagittal vault, the shape of the non-midsagittal vault and the size of the base show an extension of ontogenetic trajectories. Sexes show similar changes in shape but different changes in size. We conclude that brain growth appears to be an important factor influencing the morphology of the neurocranium, at least during infancy and childhood. Subsequent changes may be attributed to osteogenic activity and the differential growth of the brain lobes. Masticatory-related bony structures and muscles may not be strong enough factors to induce independent modifications in non-midsagittal structures. The small influence of the cranial muscles would explain why the human neurocranium is a quite integrated structure.

Morphometric variations in gametocytes of Hepatozoon canis from naturally infected dogs.

PubMed

Eljadar, Mohamed S M; Singla, L D; Mustafa, Radya A A; Uppal, S K

2013-04-01

This study presents the morphometric characteristic of canine haemoprotozoan, Hepatozoon canis, using software DP2-BSW (OLYMPUS). The gametocytes of H. canis found inside the neutrophils were characteristic in shape and size and varied from 9.50 to 11.80 μm × 5.10-6.00 μm. Parasitaemia ranged from 1.00 to 39.00 %. Few gametocytes without nuclei and of abnormal shapes were also observed. The results were compared with the measurements done by using ocular micrometer.

Method of manufacturing an overwrapped pressure vessel

NASA Technical Reports Server (NTRS)

Beck, Emory J. (Inventor)

1976-01-01

A pressure vessel of the type wherein a metallic liner in the shape of a cylindrical portion with a dome-shaped portion at each end thereof is overwrapped by a plurality of layers of resin coated, single fiberglass filaments. A four-step wrapping technique reinforces the vessel with overwrap material at the most likely areas for vessel failure. Overwrapping of the vessel is followed by a sizing pressurization cycle which induces a compressive prestress into the liner and thereby permits the liner to deform elastically through an increased strain range.

Cyclodextrin-assisted synthesis of tailored mesoporous silica nanoparticles

PubMed Central

2018-01-01

Mesoporous silica nanoparticles (MSNs) have sparked considerable interest in drug/gene delivery, catalysis, adsorption, separation, sensing, antireflection coatings and bioimaging because of their tunable structural properties. The shape, size and pore structure of MSNs are greatly influenced by the type of additives used, e.g., solvent and pore-templating agent. Here, we studied the influence of cyclodextrin (CD) molecules on the formation of MSNs. The nanoparticles over 100 nm in diameter were synthesized by surfactant-templated, hydrolysis–polycondensation reactions in the presence of pristine CD (β-CD) or hydroxypropyl-functionalized CDs (HP-γ-CD and HP-β-CD). Depending on the formulation conditions, differently shaped MSNs, such as bean-like, spherical, ellipsoid, aggregate and faceted were generated. The morphology and size of MSNs varied with the CD-type used. Generally, spherical particles were obtained with β-CD, while a faceted morphology was observed for the particles synthesized using HP-CDs. The particle size could be tuned by adjusting the amount of CD used; increasing the CD concentration led to larger particles. MSNs synthesized in the presence of β-CD displayed a smaller particle size than those produced with HP-functional CDs. FTIR, TGA and solid-state 13C NMR demonstrated the adsorption of CDs on the particle surfaces. The proposed concept allows for the synthesis of silica nanoparticles with control over particle shape and size by adjusting the concentration of additives in a simple, one-pot reaction system for a wide range of applications. PMID:29527443

Experimental and computational study of the effect of 1 atm background gas on nanoparticle generation in femtosecond laser ablation of metals

NASA Astrophysics Data System (ADS)

Wu, Han; Wu, Chengping; Zhang, Nan; Zhu, Xiaonong; Ma, Xiuquan; Zhigilei, Leonid V.

2018-03-01

Laser ablation of metal targets is actively used for generation of chemically clean nanoparticles for a broad range of practical applications. The processes involved in the nanoparticle formation at all relevant spatial and temporal scales are still not fully understood, making the precise control of the size and shape of the nanoparticles challenging. In this paper, a combination of molecular dynamics simulations and experiments is applied to investigate femtosecond laser ablation of aluminum targets in vacuum and in 1 atm argon background gas. The results of the simulations reveal a strong effect of the background gas environment on the initial plume expansion and evolution of the nanoparticle size distribution. The suppression of the generation of small/medium-size Al clusters and formation of a dense layer at the front of the expanding ablation plume, observed during the first nanosecond of the plume expansion in a simulation performed in the gas environment, have important implications on the characteristics of the nanoparticles deposited on a substrate and characterized in the experiments. The nanoparticles deposited in the gas environment are found to be more round-shaped and less flattened as compared to those deposited in vacuum. The nanoparticle size distributions exhibit power-law dependences with similar values of exponents obtained from fitting experimental and simulated data. Taken together, the results of this study suggest that the gas environment may be effectively used to control size and shape of nanoparticles generated by laser ablation.

A Monte Carlo model for 3D grain evolution during welding

NASA Astrophysics Data System (ADS)

Rodgers, Theron M.; Mitchell, John A.; Tikare, Veena

2017-09-01

Welding is one of the most wide-spread processes used in metal joining. However, there are currently no open-source software implementations for the simulation of microstructural evolution during a weld pass. Here we describe a Potts Monte Carlo based model implemented in the SPPARKS kinetic Monte Carlo computational framework. The model simulates melting, solidification and solid-state microstructural evolution of material in the fusion and heat-affected zones of a weld. The model does not simulate thermal behavior, but rather utilizes user input parameters to specify weld pool and heat-affect zone properties. Weld pool shapes are specified by Bézier curves, which allow for the specification of a wide range of pool shapes. Pool shapes can range from narrow and deep to wide and shallow representing different fluid flow conditions within the pool. Surrounding temperature gradients are calculated with the aide of a closest point projection algorithm. The model also allows simulation of pulsed power welding through time-dependent variation of the weld pool size. Example simulation results and comparisons with laboratory weld observations demonstrate microstructural variation with weld speed, pool shape, and pulsed-power.

Structure of IgG and IgY molecules in ribosome-antibody complexes as studied by electron microscopy.

PubMed

Noll, F; Lutsch, G; Bielka, H

1982-03-01

The overall shape and dimensions of IgG (rabbit) and IgY (chicken) antibodies against ribosomal proteins have been studied in electron micrographs of ribosome-antibody complexes. The antibodies appear as Y-shaped molecules with an angle of about 90 degrees between their Fab arms. The length of one Fab arm amounts to about 10 nm. No differences between the IgG and IgY molecules could be detected electron microscopically. The data obtained on the shape of IgG and IgY correlate with those of earlier electron microscopic studies while the determined size of the Fab arms is in the range found by scattering methods.

Light-dependent governance of cell shape dimensions in cyanobacteria.

PubMed

Montgomery, Beronda L

2015-01-01

The regulation of cellular dimension is important for the function and survival of cells. Cellular dimensions, such as size and shape, are regulated throughout the life cycle of bacteria and can be adapted in response to environmental changes to fine-tune cellular fitness. Cell size and shape are generally coordinated with cell growth and division. Cytoskeletal regulation of cell shape and cell wall biosynthesis and/or deposition occurs in a range of organisms. Photosynthetic organisms, such as cyanobacteria, particularly exhibit light-dependent regulation of morphogenes and generation of reactive oxygen species and other signals that can impact cellular dimensions. Environmental signals initiate adjustments of cellular dimensions, which may be vitally important for optimizing resource acquisition and utilization or for coupling the cellular dimensions with the regulation of subcellular organization to maintain optimal metabolism. Although the involvement of cytoskeletal components in the regulation of cell shape is widely accepted, the signaling factors that regulate cytoskeletal and other distinct components involved in cell shape control, particularly in response to changes in external light cues, remain to be fully elucidated. In this review, factors impacting the inter-coordination of growth and division, the relationship between the regulation of cellular dimensions and central carbon metabolism, and consideration of the effects of specific environment signals, primarily light, on cell dimensions in cyanobacteria will be discussed. Current knowledge about the molecular bases of the light-dependent regulation of cellular dimensions and cell shape in cyanobacteria will be highlighted.

Size Distribution of Genesis Solar Wind Array Collector Fragments Recovered

NASA Technical Reports Server (NTRS)

Allton, J. H.; Stansbery, E. K.; McNamara, K. M.

2005-01-01

Genesis launched in 2001 with 271 whole and 30 half hexagonally-shaped collectors mounted on 5 arrays, comprised of 9 materials described in [1]. The array collectors were damaged during re-entry impact in Utah in 2004 [2], breaking into many smaller pieces and dust. A compilation of the number and approximate size of the fragments recovered was compiled from notes made during the field packaging performed in the Class 10,000 cleanroom at Utah Test and Training Range [3].

Size and Shape of Solid Fuel Diffusion Flames in Very Low Speed Flows. M.S. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Foutch, David W.

1987-01-01

The effect of very low speed forced flows on the size and shape of a solid fuel diffusion flame are investigated experimentally. Flows due to natural convection are eliminated by performing the experiment in low gravity. The range of velocities tested is 1.5 cm/s to 6.3 cm/s and the mole fraction of oxygen in the O2/N2 atmosphere ranges from 0.15 to 0.19. The flames did not reach steady state in the 5.2 sec to which the experiment was limited. Despite limited data, trends in the transient flame temperature and, by means of extrapolation, the steady state flame size are deduced. As the flow velocity is reduced, the flames move farther from the fuel surface, and the transient flame temperature is lowered. As the oxygen concentration is reduced the flames move closer to the fuel sample and the transient flame temperature is reduced. With stand off distances up to 8.5 + or - 0.7 mm and thicknesses around 1 or 2 mm, these flames are much weaker than flames observed at normal gravity. Based on the performance of the equipment and several qualitative observations, suggestions for future work are made.

Additional Study of Water Droplet Median Volume Diameter (MVD) Effects on Ice Shapes

NASA Technical Reports Server (NTRS)

Tsao, Jen-Ching; Anderson, David N.

2005-01-01

This paper reports the result of an experimental study in the NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the MVD-independent effect identified previously might apply to SLD conditions in rime icing situations. Models were NACA 0012 wing sections with chords of 53.3 and 91.4 cm. Tests were conducted with a nominal airspeed of 77 m/s (150 kt) and a number of MVD's ranging from 15 to 100 m with LWC of 0.5 to 1 g/cu m. In the present study, ice shapes recorded from past studies and recent results at SLD and Appendix-C conditions are reviewed to show that droplet diameter is not important to rime ice shape for MVD of 30 microns or larger, but for less than 30 m drop sizes a rime ice shape transition from convex to wedge to spearhead type ice shape is observed.

Sharp and round shapes of seen objects have distinct influences on vowel and consonant articulation.

PubMed

Vainio, L; Tiainen, M; Tiippana, K; Rantala, A; Vainio, M

2017-07-01

The shape and size-related sound symbolism phenomena assume that, for example, the vowel [i] and the consonant [t] are associated with sharp-shaped and small-sized objects, whereas [ɑ] and [m] are associated with round and large objects. It has been proposed that these phenomena are mostly based on the involvement of articulatory processes in representing shape and size properties of objects. For example, [i] might be associated with sharp and small objects, because it is produced by a specific front-close shape of articulators. Nevertheless, very little work has examined whether these object properties indeed have impact on speech sound vocalization. In the present study, the participants were presented with a sharp- or round-shaped object in a small or large size. They were required to pronounce one out of two meaningless speech units (e.g., [i] or [ɑ]) according to the size or shape of the object. We investigated how a task-irrelevant object property (e.g., the shape when responses are made according to size) influences reaction times, accuracy, intensity, fundamental frequency, and formant 1 and formant 2 of vocalizations. The size did not influence vocal responses but shape did. Specifically, the vowel [i] and consonant [t] were vocalized relatively rapidly when the object was sharp-shaped, whereas [u] and [m] were vocalized relatively rapidly when the object was round-shaped. The study supports the view that the shape-related sound symbolism phenomena might reflect mapping of the perceived shape with the corresponding articulatory gestures.

Electrochemical synthesis and characterization of zinc oxalate nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com; Roushani, Mahmoud; Department of Chemistry, Ilam University, Ilam

2013-03-15

Highlights: ► Synthesis of zinc oxalate nanoparticles via electrolysis of a zinc plate anode in sodium oxalate solutions. ► Design of a Taguchi orthogonal array to identify the optimal experimental conditions. ► Controlling the size and shape of particles via applied voltage and oxalate concentration. ► Characterization of zinc oxalate nanoparticles by SEM, UV–vis, FT-IR and TG–DTA. - Abstract: A rapid, clean and simple electrodeposition method was designed for the synthesis of zinc oxalate nanoparticles. Zinc oxalate nanoparticles in different size and shapes were electrodeposited by electrolysis of a zinc plate anode in sodium oxalate aqueous solutions. It was foundmore » that the size and shape of the product could be tuned by electrolysis voltage, oxalate ion concentration, and stirring rate of electrolyte solution. A Taguchi orthogonal array design was designed to identify the optimal experimental conditions. The morphological characterization of the product was carried out by scanning electron microscopy. UV–vis and FT-IR spectroscopies were also used to characterize the electrodeposited nanoparticles. The TG–DTA studies of the nanoparticles indicated that the main thermal degradation occurs in two steps over a temperature range of 350–430 °C. In contrast to the existing methods, the present study describes a process which can be easily scaled up for the production of nano-sized zinc oxalate powder.« less

Shape and size distribution of chaos areas on Europa

NASA Astrophysics Data System (ADS)

Mikell, T.; Cox, R.

2008-12-01

Chaos terrain is ubiquitous on Europa's surface, but not randomly distributed. The global distribution of chaos areas shows a significant concentration between 30° N and S latitude, decreasing dramatically at higher latitudes. The low-latitude clustering is not an artifact of recognizability, as there is a greater proportion of images with high solar incidence angle (low light) at higher latitudes. Clustering is especially marked in context of the few but vast regional chaos tracts (>15,000 km2) that occupy a substantial proportion of the equatorial region: i.e. the low latitudes have not only greater numbers but much greater areal chaos coverage. Apex-antapex asymmetry is difficult to evaluate because the Galileo longitudinal coverage is so poor; but comparison of the image swaths that follow great circles across the leading and trailing hemispheres respectively shows greater numbers of chaos areas on the leading side. In spite of the equatorial location of a few vast chaos tracts, there is no apparent relationship between chaos area size and latitude. Chaos area outlines vary from smoothly circular to extremely jagged: the irregularity index ranges from 2- 270% (based on the ratio between measured chaos area perimeter and the circumference of a circle of equal area). There is a range of shapes in all size brackets, but smaller chaos areas on average have simpler, more equidimensional shapes, and edge complexity increases for larger chaos areas. Chaos areas of ~10 km equivalent circle diameter (ECD) have outlines that are 4-90% irregular, ones ~50 km ECD are 15-180% and those >100 km ECD are 35-270% irregular. In general, chaos areas with higher irregularity indices also have a higher raft:matrix ratio. These results, while preliminary, are consistent with experimental evidence suggesting an impact origin for some chaos terrain on Europa. In particular, the relationship between shape and size parallels the results of impact experiments into ice over water, in which lower-energy impacts produce small, circular bullet-holes with few or no rafts; and higher-energy impacts generate wide-field fragmentation of the ice, producing large and highly irregular openings with abundant floating crustal blocks.

A systematic account of the genus Plagiostoma (Gnomoniaceae, Diaporthales) based on morphology, host-associations, and a four gene phylogeny

USDA-ARS?s Scientific Manuscript database

The genus Plagiostoma inhabits leaves and branches of a range of woody and herbaceous plant families in the temperate northern hemisphere. Based on analyses of morphological, cultural, and molecular data, Plagiostoma is reviewed and monographed. The morphological data include shape and size of perit...

Shape-morphing composites with designed micro-architectures

NASA Astrophysics Data System (ADS)

Rodriguez, Jennifer N.; Zhu, Cheng; Duoss, Eric B.; Wilson, Thomas S.; Spadaccini, Christopher M.; Lewicki, James P.

2016-06-01

Shape memory polymers (SMPs) are attractive materials due to their unique mechanical properties, including high deformation capacity and shape recovery. SMPs are easier to process, lightweight, and inexpensive compared to their metallic counterparts, shape memory alloys. However, SMPs are limited to relatively small form factors due to their low recovery stresses. Lightweight, micro-architected composite SMPs may overcome these size limitations and offer the ability to combine functional properties (e.g., electrical conductivity) with shape memory behavior. Fabrication of 3D SMP thermoset structures via traditional manufacturing methods is challenging, especially for designs that are composed of multiple materials within porous microarchitectures designed for specific shape change strategies, e.g. sequential shape recovery. We report thermoset SMP composite inks containing some materials from renewable resources that can be 3D printed into complex, multi-material architectures that exhibit programmable shape changes with temperature and time. Through addition of fiber-based fillers, we demonstrate printing of electrically conductive SMPs where multiple shape states may induce functional changes in a device and that shape changes can be actuated via heating of printed composites. The ability of SMPs to recover their original shapes will be advantageous for a broad range of applications, including medical, aerospace, and robotic devices.

Single-Step Fabrication of Computationally Designed Microneedles by Continuous Liquid Interface Production

PubMed Central

Johnson, Ashley R.; Caudill, Cassie L.; Tumbleston, John R.; Bloomquist, Cameron J.; Moga, Katherine A.; Ermoshkin, Alexander; Shirvanyants, David; Mecham, Sue J.; Luft, J. Christopher; DeSimone, Joseph M.

2016-01-01

Microneedles, arrays of micron-sized needles that painlessly puncture the skin, enable transdermal delivery of medications that are difficult to deliver using more traditional routes. Many important design parameters, such as microneedle size, shape, spacing, and composition, are known to influence efficacy, but are notoriously difficult to alter due to the complex nature of microfabrication techniques. Herein, we utilize a novel additive manufacturing (“3D printing”) technique called Continuous Liquid Interface Production (CLIP) to rapidly prototype sharp microneedles with tuneable geometries (size, shape, aspect ratio, spacing). This technology allows for mold-independent, one-step manufacturing of microneedle arrays of virtually any design in less than 10 minutes per patch. Square pyramidal CLIP microneedles composed of trimethylolpropane triacrylate, polyacrylic acid and photopolymerizable derivatives of polyethylene glycol and polycaprolactone were fabricated to demonstrate the range of materials that can be utilized within this platform for encapsulating and controlling the release of therapeutics. These CLIP microneedles effectively pierced murine skin ex vivo and released the fluorescent drug surrogate rhodamine. PMID:27607247

Colloidal Inorganic Nanocrystal Based Nanocomposites: Functional Materials for Micro and Nanofabrication

PubMed Central

Ingrosso, Chiara; Panniello, AnnaMaria; Comparelli, Roberto; Curri, Maria Lucia; Striccoli, Marinella

2010-01-01

The unique size- and shape-dependent electronic properties of nanocrystals (NCs) make them extremely attractive as novel structural building blocks for constructing a new generation of innovative materials and solid-state devices. Recent advances in material chemistry has allowed the synthesis of colloidal NCs with a wide range of compositions, with a precise control on size, shape and uniformity as well as specific surface chemistry. By incorporating such nanostructures in polymers, mesoscopic materials can be achieved and their properties engineered by choosing NCs differing in size and/or composition, properly tuning the interaction between NCs and surrounding environment. In this contribution, different approaches will be presented as effective opportunities for conveying colloidal NC properties to nanocomposite materials for micro and nanofabrication. Patterning of such nanocomposites either by conventional lithographic techniques and emerging patterning tools, such as ink jet printing and nanoimprint lithography, will be illustrated, pointing out their technological impact on developing new optoelectronic and sensing devices.

Gamma ray evaluation of fast neutron irradiated on topaz from Sri Lanka by HPGe gamma ray spectrometry

NASA Astrophysics Data System (ADS)

Boonsook, K.; Kaewwiset, W.; Limsuwan, P.; Naemchanthara, K.

2017-09-01

The purpose of this study was to evaluate the radionuclide concentrations of London blue topaz after fast neutron irradiation. The London blue topaz was obtained from Sri Lanka which classified into dark and light colors in the shape of an oval and rectangle with small, medium and large size. The optical property and radionuclide concentrations of London blue topaz have been examine by UV-Visible spectroscopy and HPGe gamma ray spectrometry, respectively. The UV-absorption spectra of topaz was taken in the range of 300 to 800 nm at room temperature. The results showed that the absorption peak of topaz was observed with only broad peaks in the range of 550 to 700 nm and 630 nm that correlated to the O - center in hydroxyl sites which substitutes for fluorine in topaz structure. The radioactivity of dark and light colors in the shape of an oval and rectangle London blue topaz was in the range of 1.437 ± 0.014 to 21.551 ± 0.037 nCi/g (oval dark), 2.958 ± 0.031 to 6.748 ± 0.054 nCi/g (oval light) and 2.350 ± 0.014 to 43.952 ± 0.088 nCi/g (rectangle dark), 1.442 ± 0.023 to 6.748 ± 0.054 nCi/g (rectangle light), respectively. The decay rates of 46Sc, 182Ta and 54Mn isotopes created by irradiation showed that the decay time of the radioactive element depended on the size of the topaz so increased with decreasing the size of topaz. Moreover, the size of topaz also affect the absorption coefficient. This study is applied to predict time of residue dose of topaz for enhancement colorless topaz by neutron radiation treatment.

Electron beam fabrication of a microfluidic device for studying submicron-scale bacteria

PubMed Central

2013-01-01

Background Controlled restriction of cellular movement using microfluidics allows one to study individual cells to gain insight into aspects of their physiology and behaviour. For example, the use of micron-sized growth channels that confine individual Escherichia coli has yielded novel insights into cell growth and death. To extend this approach to other species of bacteria, many of whom have dimensions in the sub-micron range, or to a larger range of growth conditions, a readily-fabricated device containing sub-micron features is required. Results Here we detail the fabrication of a versatile device with growth channels whose widths range from 0.3 μm to 0.8 μm. The device is fabricated using electron beam lithography, which provides excellent control over the shape and size of different growth channels and facilitates the rapid-prototyping of new designs. Features are successfully transferred first into silicon, and subsequently into the polydimethylsiloxane that forms the basis of the working microfluidic device. We demonstrate that the growth of sub-micron scale bacteria such as Lactococcus lactis or Escherichia coli cultured in minimal medium can be followed in such a device over several generations. Conclusions We have presented a detailed protocol based on electron beam fabrication together with specific dry etching procedures for the fabrication of a microfluidic device suited to study submicron-sized bacteria. We have demonstrated that both Gram-positive and Gram-negative bacteria can be successfully loaded and imaged over a number of generations in this device. Similar devices could potentially be used to study other submicron-sized organisms under conditions in which the height and shape of the growth channels are crucial to the experimental design. PMID:23575419

A Waveguide Antenna with an Extended Angular Range for Remote Steering of Wave-Beam Direction

NASA Astrophysics Data System (ADS)

Sobolev, D. I.; Denisov, G. G.

2018-03-01

A new method for increasing the angular range of a waveguide antenna for remote steering of the wave-beam direction in thermonuclear-fusion experimental setups with plasma magnetic confinement is proposed. Characteristics for large beam inclination angles can be improved using the synthesized nonuniform waveguide profile. For small angles, the characteristics remain invariable, the waveguide profile differs only slightly from the regular shape, and can be fit to limited waveguide-channel sizes.

SU-8 Lenses: Simple Methods of Fabrication and Application in Optical Interconnection Between Fiber/LED and Microstructures

NASA Astrophysics Data System (ADS)

Nguyen, Minh-Hang; Nguyen, Hai-Binh; Nguyen, Tuan-Hung; Vu, Xuan-Manh; Lai, Jain-Ren; Tseng, Fan-Gang; Chen, Te-Chang; Lee, Ming-Chang

2016-05-01

This paper presents two facile methods to fabricate off-plane lenses made of SU-8, an epoxy-based negative photoresist from MicroChem, on glass for optical interconnection. The methods allow the fabrication of lenses with flexible spot size and focal length depending on SU-8 well size and SU-8 drop volume and viscosity. In the first method, SU-8 drops were applied directly into patterned SU-8 wells with Teflon-coated micropipettes, and were baked to become (a)-spherical lenses. The lens shape and size were mainly determined by SU-8 viscosity, ratio of drop volume to well volume, and baking temperature and time. In the second method, a glass substrate with SU-8 patterned wells was emerged in diluted SU-8, then drawn up and baked to form lenses. The lens shapes and sizes were mainly determined by SU-8 viscosity and well volume. By the two methods, SU-8 lenses were successfully fabricated with spot sizes varying in range from micrometers to hundred micrometers, and focal lengths varying in range of several millimeters, depending on the lens rim diameters and aspheric sag height. Besides, on-plane SU-8 lenses were fabricated by photolithography to work in conjunction with the off-plane SU-8 lenses. The cascaded lenses produced light spots reduced to several micrometers, and they can be applied as a coupler for light coupling from fiber/Light-emitting diode (LED) to microstructures and nanostructures. The results open up the path for fabricating novel optical microsystems for optical communication and optical sensing applications.

Stereoscopic shape discrimination is well preserved across changes in object size.

PubMed

Norman, J Farley; Swindle, Jessica M; Jennings, L RaShae; Mullins, Elizabeth M; Beers, Amanda M

2009-06-01

A single experiment evaluated human observers' ability to discriminate the shape of solid objects that varied in size and orientation in depth. The object shapes were defined by binocular disparity, Lambertian shading, and texture. The object surfaces were smoothly curved and had naturalistic shapes, resembling those of water-smoothed granite rocks. On any given trial, two objects were presented that were either the same or different in terms of shape. When the "same" objects were presented, they differed in their orientation in depth by 25 degrees , 45 degrees , or 65 degrees . The observers were required to judge whether any given pair of objects was the "same" or "different" in terms of shape. The size of the objects was also varied by amounts up to +/-40% relative to the standard size. The observers' shape discrimination performance was strongly affected by the magnitude of the orientation changes in depth - thus, their performance was viewpoint dependent. In contrast, the observers' shape discrimination abilities were only slightly affected by changes in the overall size of the objects. It appears that human observers can recognize the three-dimensional shape of objects in a manner that is relatively independent of size.

Effect of interparticle interactions on size determination of zirconia and silica based systems – A comparison of SAXS, DLS, BET, XRD and TEM

PubMed Central

Pabisch, Silvia; Feichtenschlager, Bernhard; Kickelbick, Guido; Peterlik, Herwig

2012-01-01

The aim of this work is a systematic comparison of size characterisation methods for two completely different model systems of oxide nanoparticles, i.e. amorphous spherical silica and anisotropic facet-shaped crystalline zirconia. Size and/or size distribution were determined in a wide range from 5 to 70 nm using small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), nitrogen sorption (BET), X-ray diffraction (XRD) and transmission electron microscopy (TEM). A nearly perfect coincidence was observed only for SAXS and TEM for both types of particles. For zirconia nanoparticles considerable differences between different measurement methods were observed. PMID:22347721

A Sensitivity Study on the Effects of Particle Chemistry, Asphericity and Size on the Mass Extinction Efficiency of Mineral Dust in the Earth's Atmosphere: From the Near to Thermal IR

NASA Technical Reports Server (NTRS)

Hansell, R. A., Jr.; Reid, J. S.; Tsay, S. C.; Roush, T. L.; Kalashnikova, O. V.

2011-01-01

To determine a plausible range of mass extinction efficiencies (MEE) of terrestrial atmospheric dust from the near to thermal IR, sensitivity analyses are performed over an extended range of dust microphysical and chemistry perturbations. The IR values are subsequently compared to those in the near-IR, to evaluate spectral relationships in their optical properties. Synthesized size distributions consistent with measurements, model particle size, while composition is defined by the refractive indices of minerals routinely observed in dust, including the widely used OPAC/Hess parameterization. Single-scattering properties of representative dust particle shapes are calculated using the T-matrix, Discrete Dipole Approximation and Lorenz-Mie light-scattering codes. For the parameterizations examined, MEE ranges from nearly zero to 1.2 square meters per gram, with the higher values associated with non-spheres composed of quartz and gypsum. At near-IR wavelengths, MEE for non-spheres generally exceeds those for spheres, while in the thermal IR, shape-induced changes in MEE strongly depend on volume median diameter (VMD) and wavelength, particularly for MEE evaluated at the mineral resonant frequencies. MEE spectral distributions appear to follow particle geometry and are evidence for shape dependency in the optical properties. It is also shown that non-spheres best reproduce the positions of prominent absorption peaks found in silicates. Generally, angular particles exhibit wider and more symmetric MEE spectral distribution patterns from 8-10 micrometers than those with smooth surfaces, likely due to their edge-effects. Lastly, MEE ratios allow for inferring dust optical properties across the visible-IR spectrum. We conclude the MEE of dust aerosol are significant for the parameter space investigated, and are a key component for remote sensing applications and the study of direct aerosol radiative effects.

Size-Sensitive Perceptual Representations Underlie Visual and Haptic Object Recognition

PubMed Central

Craddock, Matt; Lawson, Rebecca

2009-01-01

A variety of similarities between visual and haptic object recognition suggests that the two modalities may share common representations. However, it is unclear whether such common representations preserve low-level perceptual features or whether transfer between vision and haptics is mediated by high-level, abstract representations. Two experiments used a sequential shape-matching task to examine the effects of size changes on unimodal and crossmodal visual and haptic object recognition. Participants felt or saw 3D plastic models of familiar objects. The two objects presented on a trial were either the same size or different sizes and were the same shape or different but similar shapes. Participants were told to ignore size changes and to match on shape alone. In Experiment 1, size changes on same-shape trials impaired performance similarly for both visual-to-visual and haptic-to-haptic shape matching. In Experiment 2, size changes impaired performance on both visual-to-haptic and haptic-to-visual shape matching and there was no interaction between the cost of size changes and direction of transfer. Together the unimodal and crossmodal matching results suggest that the same, size-specific perceptual representations underlie both visual and haptic object recognition, and indicate that crossmodal memory for objects must be at least partly based on common perceptual representations. PMID:19956685

The Effect of Particle Size on the Biodistribution of Low-modulus Hydrogel PRINT Particles

PubMed Central

Merkel, Timothy J.; Chen, Kai; Jones, Stephen W.; Pandya, Ashish A.; Tian, Shaomin; Napier, Mary E.; Zamboni, William E.; DeSimone, Joseph M.

2012-01-01

There is a growing recognition that the deformability of particles used for drug delivery plays a significant role on their biodistribution and circulation profile. Understanding these effects would provide a crucial tool for the rational design of drug delivery systems. While particles resembling red blood cells (RBCs) in size, shape and deformability have extended circulation times and altered biodistribution profiles compared to rigid, but otherwise similar particles, the in vivo behavior of such highly deformable particles of varied size has not been explored. We report the fabrication of a series of discoid, monodisperse, low-modulus hydrogel particles with diameters ranging from 0.8 to 8.9 μm, spanning sizes smaller than and larger than RBCs. We injected these particles into healthy mice, and tracked their concentration in the blood and their distribution into major organs. These deformable particles all demonstrated some hold up in filtration tissues like the lungs and spleen, followed by release back into the circulation, characterized by decreases in particles in these tissues with concomitant increases in particle concentration in blood. Particles similar to red blood cells in size demonstrated longer circulation times, suggesting that this size and shape of deformable particle is uniquely suited to avoid clearance. PMID:22705460

Influence of particle aspect ratio on the midinfrared extinction spectra of wavelength-sized ice crystals.

PubMed

Wagner, Robert; Benz, Stefan; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin; Leisner, Thomas

2007-12-20

We have used the T-matrix method and the discrete dipole approximation to compute the midinfrared extinction cross-sections (4500-800 cm(-1)) of randomly oriented circular ice cylinders for aspect ratios extending up to 10 for oblate and down to 1/6 for prolate particle shapes. Equal-volume sphere diameters ranged from 0.1 to 10 microm for both particle classes. A high degree of particle asphericity provokes a strong distortion of the spectral habitus compared to the extinction spectrum of compactly shaped ice crystals with an aspect ratio around 1. The magnitude and the sign (increase or diminution) of the shape-related changes in both the absorption and the scattering cross-sections crucially depend on the particle size and the values for the real and imaginary part of the complex refractive index. When increasing the particle asphericity for a given equal-volume sphere diameter, the values for the overall extinction cross-sections may change in opposite directions for different parts of the spectrum. We have applied our calculations to the analysis of recent expansion cooling experiments on the formation of cirrus clouds, performed in the large coolable aerosol and cloud chamber AIDA of Forschungszentrum Karlsruhe at a temperature of 210 K. Depending on the nature of the seed particles and the temperature and relative humidity characteristics during the expansion, ice crystals of various shapes and aspect ratios could be produced. For a particular expansion experiment, using Illite mineral dust particles coated with a layer of secondary organic matter as seed aerosol, we have clearly detected the spectral signatures characteristic of strongly aspherical ice crystal habits in the recorded infrared extinction spectra. We demonstrate that the number size distributions and total number concentrations of the ice particles that were generated in this expansion run can only be accurately derived from the recorded infrared spectra when employing aspect ratios as high as 10 in the retrieval approach. Remarkably, the measured spectra could also be accurately fitted when employing an aspect ratio of 1 in the retrieval. The so-deduced ice particle number concentrations, however, exceeded the true values, determined with an optical particle counter, by more than 1 order of magnitude. Thus, the shape-induced spectral changes between the extinction spectra of platelike ice crystals of aspect ratio 10 and compactly shaped particles of aspect ratio 1 can be efficiently balanced by deforming the true number size distribution of the ice cloud. As a result of this severe size/shape ambiguity in the spectral analysis, we consider it indispensable to cross-check the infrared retrieval results of wavelength-sized ice particles with independent reference measurements of either the number size distribution or the particle morphology.

Internal field distribution of a radially inhomogeneous droplet illuminated by an arbitrary shaped beam

NASA Astrophysics Data System (ADS)

Wang, Jia Jie; Wriedt, Thomas; Han, Yi Ping; Mädler, Lutz; Jiao, Yong Chang

2018-05-01

Light scattering of a radially inhomogeneous droplet, which is modeled by a multilayered sphere, is investigated within the framework of Generalized Lorenz-Mie Theory (GLMT), with particular efforts devoted to the analysis of the internal field distribution in the cases of shaped beam illumination. To circumvent numerical difficulties in the computation of internal field for an absorbing/non-absorbing droplet with pretty large size parameter, a recursive algorithm is proposed by reformulation of the equations for the expansion coefficients. Two approaches are proposed for the prediction of the internal field distribution, namely a rigorous method and an approximation method. The developed computer code is tested to be stable in a wide range of size parameters. Numerical computations are implemented to simulate the internal field distributions of a radially inhomogeneous droplet illuminated by a focused Gaussian beam.

Aesthetic breast shape preferences among plastic surgeons.

PubMed

Broer, Peter Niclas; Juran, Sabrina; Walker, Marc E; Ng, Reuben; Weichman, Katie; Tanna, Neil; Liu, Yuen-Jong; Shah, Ajul; Patel, Anup; Persing, John A; Thomson, James Grant

2015-06-01

There has been little discussion in the plastic surgery literature regarding breast shape preferences among plastic surgeons, despite strong evidence that such aesthetic preferences are influenced by multiple factors. Much effort has been focused on delineating the objective criteria by which an "attractive" breast might be defined. This study aimed at providing a better understanding of the presence and significance of differences in personal aesthetic perception, and how these relate to a plastic surgeon's demographic, ethnic, and cultural background, as well as practice type (academic vs private). An interactive online survey was designed. Modifiable ranges of upper pole fullness and areola size were achieved via digital alteration, enabling participants to interactively change the shape of a model's breasts. The questionnaire was translated into multiple languages and sent to plastic surgeons worldwide. Demographic data were also collected. Analysis of variance was used to elucidate plastic surgeon's breast shape preferences in respect to sex and age, geographic and ethnic background, as well as practice type. The authors gathered 614 responses from 29 different countries. Significant differences regarding preferences for upper pole fullness, areola size in the natural breast, and areola size in the augmented breast were identified across surgeons from the different countries. Further, significant relationships regarding breast shape preferences were distilled between the age and sex of the surgeon, as well as the practice type. No differences were found in respect to the surgeons' self-reported ethnic background. Country of residence, age, and practice type significantly impact breast shape preferences of plastic surgeons. These findings have implications for both patients seeking and surgeons performing cosmetic and reconstructive breast surgery. In an increasingly global environment, cultural differences and international variability must be considered when defining and publishing new techniques and aesthetic outcomes. When both the plastic surgeon and the patient are able to adequately and effectively communicate their preferences regarding the shape and relations of the breast, they will be more successful at achieving satisfying results.

Carbon dioxide crystals: An examination of their size, shape, and scattering properties at 37 GHz and comparisons with water ice (snow) measurements

NASA Astrophysics Data System (ADS)

Foster, J. L.; Chang, A. T. C.; Hall, D. K.; Wergin, W. P.; Erbe, E. F.; Barton, J.

1998-11-01

On Earth, the temperature regime is such that water is generally fairly close to its freezing point, and thus relatively small differences in climate affect how much snow and ice are present and whether or not the snow covering will be seasonal or last from one year to the next. On Mars, as on Earth, the presence of ice also plays a role in large-scale climate processes and it is important in controlling the abundance of atmospheric carbon dioxide (CO2) and water vapor. Passive microwave radiometry has been used to derive snow extent and snow depth on Earth, where scattering by snow (H2O) crystals is the dominant effect on the microwave radiation emanating from the ground and emerging from the snowpack. Microwave remote sensing may also prove to be useful for assessing the coverage and thickness of the frozen H2O and CO2 on Mars, but more exact information is needed on how both H2O crystals and frozen CO2 crystals scatter and absorb passive microwave radiation. In this study, CO2 crystals have been produced in a laboratory cold chamber with temperature conditions similar to those found on the polar caps of Mars, and detailed three-dimensional images of their size and shape have been made with a low-temperature scanning electron microscope. Unlike the much larger H2O snow crystals found on Earth, which typically range in size between 0.1 mm and 1.0 mm (radius), CO2 crystals are differently shaped and considerably smaller. Bipyramid crystals (base to base four-sided pyramids) are commonly observed, some as small as 1.0 μm. A discrete dipole model was employed to calculate the passive microwave radiation scattered and absorbed by crystals of various sizes and shapes. Modeling results indicate that the shape of the crystal, whether for frozen CO2 or H2O, is of little consequence in affecting extinction efficiency. However, owing to their smaller size, frozen CO2 crystals are more emissive than the H2O crystals in the 37 GHz region of the microwave spectrum. For the larger sizes of the modeled crystals, scattering dominates over absorption since the particles approach the size of the wavelength. The scattering values are 2 orders of magnitude larger than absorption for the 900 μm size snow particles. For CO2 crystals of 3.0 μm in size, absorption is 7 orders of magnitude greater than scattering.

Design of Compact Flower Shape Dual Notched-Band Monopole Antenna for Extended UWB Wireless Applications

NASA Astrophysics Data System (ADS)

Sharma, Manish; Awasthi, Y. K.; Singh, Himanshu; Kumar, Raj; Kumari, Sarita

2016-11-01

In this letter, a compact monopole antenna for ultra wideband (UWB) applications is proposed with small size of 18×20=360 mm2. Antenna consist of a flower shape radiating patch with a pair of C-shaped slots which offer two notch bands for WiMAX (3.04-3.68 GHz) & WLAN (4.73-5.76 GHz) and two rectangular shaped slots in the ground plane which provides a wide measured usable fractional extended bandwidth of 163 % (2.83-14.0 GHz) with improved VSWR. Moreover, it is also convenient for other wireless application as close range radar, 8-12 GHz in X-band. Measured radiation patterns exhibits nearly omnidirectional in H-plane and dipole like pattern in E-plane across the bandwidth and furthermore exhibits good time domain performance.

Ultra low density biodegradable shape memory polymer foams with tunable physical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singhal, Pooja; Wilson, Thomas S.; Cosgriff-Hernandez, Elizabeth

Compositions and/or structures of degradable shape memory polymers (SMPs) ranging in form from neat/unfoamed to ultra low density materials of down to 0.005 g/cc density. These materials show controllable degradation rate, actuation temperature and breadth of transitions along with high modulus and excellent shape memory behavior. A method of m ly low density foams (up to 0.005 g/cc) via use of combined chemical and physical aking extreme blowing agents, where the physical blowing agents may be a single compound or mixtures of two or more compounds, and other related methods, including of using multiple co-blowing agents of successively higher boilingmore » points in order to achieve a large range of densities for a fixed net chemical composition. Methods of optimization of the physical properties of the foams such as porosity, cell size and distribution, cell openness etc. of these materials, to further expand their uses and improve their performance.« less

Detecting personnel around UGVs using stereo vision

NASA Astrophysics Data System (ADS)

Bajracharya, Max; Moghaddam, Baback; Howard, Andrew; Matthies, Larry H.

2008-04-01

Detecting people around unmanned ground vehicles (UGVs) to facilitate safe operation of UGVs is one of the highest priority issues in the development of perception technology for autonomous navigation. Research to date has not achieved the detection ranges or reliability needed in deployed systems to detect upright pedestrians in flat, relatively uncluttered terrain, let alone in more complex environments and with people in postures that are more difficult to detect. Range data is essential to solve this problem. Combining range data with high resolution imagery may enable higher performance than range data alone because image appearance can complement shape information in range data and because cameras may offer higher angular resolution than typical range sensors. This makes stereo vision a promising approach for several reasons: image resolution is high and will continue to increase, the physical size and power dissipation of the cameras and computers will continue to decrease, and stereo cameras provide range data and imagery that are automatically spatially and temporally registered. We describe a stereo vision-based pedestrian detection system, focusing on recent improvements to a shape-based classifier applied to the range data, and present frame-level performance results that show great promise for the overall approach.

Crystallographically Anisotropic Shape of Forsterite: New Probe for Evaluating Dust Formation History from Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Takigawa, Aki; Tachibana, Shogo

2012-05-01

Crystalline dust has been observed by infrared spectroscopy around dust-enshrouded asymptotic giant branch stars, in protoplanetary disks, and from some comets. Crystalline materials often have a specific shape related to a specific crystallographic orientation (crystallographically anisotropic shape), which reflects the anisotropic nature of crystals, and their infrared spectral features depend on crystallographically anisotropic shapes. The crystallographically anisotropic shape is thus a potentially powerful probe to evaluate circumstellar dust-forming conditions quantitatively. In order to assess the possibility to determine the crystallographically anisotropic shape from infrared spectra, we calculated mass absorption coefficients for ellipsoidal forsterite particles, the most abundant circumstellar crystalline silicate, elongated and flattened along the crystallographic a-, b-, and c-axes with various aspect ratios in the wavelength range of 9-70 μm. It was found that differences in infrared features caused by various crystallographicaly anisotropic shapes are distinguishable from each other irrespective of the effects of temperature, size, chemical composition, and grain edges of forsterite in the range of 9-12 μm and 15-20 μm. We thus concluded that the crystallographically anisotropic shape of forsterite can be deduced from peak features in infrared spectra. We also showed that the crystallographically anisotropic shapes formed by evaporation and condensation of forsterite can be distinguished from each other and the temperature condition for evaporation can be evaluated from the peak features. We applied the present results to the infrared spectrum of a protoplanetary disk HD100546 and found that a certain fraction (~25%) of forsterite dust may have experienced high-temperature evaporation (>1600 K).

Bony pelvic canal size and shape in relation to body proportionality in humans.

PubMed

Kurki, Helen K

2013-05-01

Obstetric selection acts on the female pelvic canal to accommodate the human neonate and contributes to pelvic sexual dimorphism. There is a complex relationship between selection for obstetric sufficiency and for overall body size in humans. The relationship between selective pressures may differ among populations of different body sizes and proportions, as pelvic canal dimensions vary among populations. Size and shape of the pelvic canal in relation to body size and shape were examined using nine skeletal samples (total female n = 57; male n = 84) from diverse geographical regions. Pelvic, vertebral, and lower limb bone measurements were collected. Principal component analyses demonstrate pelvic canal size and shape differences among the samples. Male multivariate variance in pelvic shape is greater than female variance for North and South Africans. High-latitude samples have larger and broader bodies, and pelvic canals of larger size and, among females, relatively broader medio-lateral dimensions relative to low-latitude samples, which tend to display relatively expanded inlet antero-posterior (A-P) and posterior canal dimensions. Differences in canal shape exist among samples that are not associated with latitude or body size, suggesting independence of some canal shape characteristics from body size and shape. The South Africans are distinctive with very narrow bodies and small pelvic inlets relative to an elongated lower canal in A-P and posterior lengths. Variation in pelvic canal geometry among populations is consistent with a high degree of evolvability in the human pelvis. Copyright © 2013 Wiley Periodicals, Inc.

WIDE AND THICK GRAIN 1, which encodes an otubain-like protease with deubiquitination activity, influences grain size and shape in rice.

PubMed

Huang, Ke; Wang, Dekai; Duan, Penggen; Zhang, Baolan; Xu, Ran; Li, Na; Li, Yunhai

2017-09-01

Grain size and shape are two crucial traits that influence grain yield and grain appearance in rice. Although several factors that affect grain size have been described in rice, the molecular mechanisms underlying the determination of grain size and shape are still elusive. In this study we report that WIDE AND THICK GRAIN 1 (WTG1) functions as an important factor determining grain size and shape in rice. The wtg1-1 mutant exhibits wide, thick, short and heavy grains and also shows an increased number of grains per panicle. WTG1 determines grain size and shape mainly by influencing cell expansion. WTG1 encodes an otubain-like protease, which shares similarity with human OTUB1. Biochemical analyses indicate that WTG1 is a functional deubiquitinating enzyme, and the mutant protein (wtg1-1) loses this deubiquitinating activity. WTG1 is expressed in developing grains and panicles, and the GFP-WTG1 fusion protein is present in the nucleus and cytoplasm. Overexpression of WTG1 results in narrow, thin, long grains due to narrow and long cells, further supporting the role of WTG1 in determining grain size and shape. Thus, our findings identify the otubain-like protease WTG1 to be an important factor that determines grain size and shape, suggesting that WTG1 has the potential to improve grain size and shape in rice. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

Shape, size, and maturity trajectories of the human ilium.

PubMed

Wilson, Laura A B; Ives, Rachel; Cardoso, Hugo F V; Humphrey, Louise T

2015-01-01

Morphological traits of the ilium have consistently been more successful for juvenile sex determination than have techniques applied to other skeletal elements, however relatively little is known about the ontogeny and maturation of size and shape dimorphism in the ilium. We use a geometric morphometric approach to quantitatively separate the ontogeny of size and shape of the ilium, and analyze interpopulation differences in the onset, rate and patterning of sexual dimorphism. We captured the shape of three traits for a total of 191 ilia from Lisbon (Portugal) and London (UK) samples of known age and sex (0-17 years). Our results indicate that a) there is a clear dissociation between the ontogeny of size and shape in males and females, b) the ontogeny of size and shape are each defined by non-linear trajectories that differ between the sexes, c) there are interpopulation differences in ontogenetic shape trajectories, which point to population-specific patterning in the attainment of sexual dimorphism, and d) the rate of shape maturation and size maturation is typically higher for females than males. Male and female shape differences in the ilium are brought about by trajectory divergence. Differences in size and shape maturation between the sexes suggest that maturity may confound our ability to discriminate between the sexes by introducing variation not accounted for in age-based groupings. The accuracy of sex determination methods using the ilium may be improved by the use of different traits for particular age groups, to capture the ontogenetic development of shape in both sexes. © 2014 Wiley Periodicals, Inc.

Computational model for behavior shaping as an adaptive health intervention strategy.

PubMed

Berardi, Vincent; Carretero-González, Ricardo; Klepeis, Neil E; Ghanipoor Machiani, Sahar; Jahangiri, Arash; Bellettiere, John; Hovell, Melbourne

2018-03-01

Adaptive behavioral interventions that automatically adjust in real-time to participants' changing behavior, environmental contexts, and individual history are becoming more feasible as the use of real-time sensing technology expands. This development is expected to improve shortcomings associated with traditional behavioral interventions, such as the reliance on imprecise intervention procedures and limited/short-lived effects. JITAI adaptation strategies often lack a theoretical foundation. Increasing the theoretical fidelity of a trial has been shown to increase effectiveness. This research explores the use of shaping, a well-known process from behavioral theory for engendering or maintaining a target behavior, as a JITAI adaptation strategy. A computational model of behavior dynamics and operant conditioning was modified to incorporate the construct of behavior shaping by adding the ability to vary, over time, the range of behaviors that were reinforced when emitted. Digital experiments were performed with this updated model for a range of parameters in order to identify the behavior shaping features that optimally generated target behavior. Narrowing the range of reinforced behaviors continuously in time led to better outcomes compared with a discrete narrowing of the reinforcement window. Rapid narrowing followed by more moderate decreases in window size was more effective in generating target behavior than the inverse scenario. The computational shaping model represents an effective tool for investigating JITAI adaptation strategies. Model parameters must now be translated from the digital domain to real-world experiments so that model findings can be validated.

Constraints on the size of Asteroid (216) Kleopatra using stress analysis

NASA Astrophysics Data System (ADS)

Hirabayashi, M.; Scheeres, D. J.

2013-12-01

We investigate the stable size of Asteroid (216) Kleopatra by considering structural constraints on this body. Comprehensive radar observations (Ostro et al. 2000, Science) were used to estimate a shape model for this asteroid. Their estimation revealed that the shape looks like a dog-bone, the mean radius is 54.3 km (with uncertainty as large as 25%), and the surface seems similar to lunar surface regolith. However, 10 years later, Descamps et al. (2011, Icarus) performed near-infrared adaptive optics (AO) imaging with the W.M. Keck II telescope and found that although the shape may be consistent with their observation result, their size appeared to be larger than the Ostro size (by a factor of about 1.24). Our motivation in this study is to investigate structural stability constraints on the size of this asteroid. Across the stated range of uncertainty we find significant differences in the necessary angle of friction and cohesion for the body to avoid plastic deformation. We use the following physical parameters as fixed: a mass of 4.64e18 kg (Descamps et al. 2011, Icarus), a rotation period of 5.385 hr (Magnusson 1990, Icarus), and the Ostro et al. shape. We use the Drucker-Prager criterion to describe the rheology of the asteroid's material. Furthermore, we determine the friction angle from the fact that the surface of this asteroid is similar to lunar surface regolith, whose porosity ranges from 33% to 55%. According to Scott (1963), a soil with porosity of 44% (the mean value of the lunar surface porosity) has a friction angle of 32 degrees (which we use as our nominal value). Since the interior structure is unknown, we assume that the body is homogeneous. We first analyze the stable size by using the upper bound theorem from limit analysis on the assumption that this asteroid's materials are cohesionless. Based on this theorem, for any static surface traction and body force, the yield due to a smooth and convex yield envelope associated with the volume average is identical to the upper bound (Holsapple 2008, INT J NONLINEAR MECH). For the average stress, we give total volume (Holsapple, 2008, Icarus) and partial volume (Hirabayashi et al., 2013, ApJ, submitted). This method gives a conservative condition for structural failure. The result shows that if the size is between 1.18 and 1.32 (a scaling factor defined such that the Ostro shape's size has a value of 1.0), (216) Kleopatra is structurally stable, which is consistent with Descamps et al. (2011, Icaurus). Next, we calculate plastic stress solutions to determine possible actual structural failure regimes. For this computation, we use commercial finite element analysis software (ANSYS Academic Teaching Introductory 14.0). To determine structural failure, we search for the condition where a plastic region propagates over the majority of a cross section. Since the zero-cohesion condition leads to large plastic deformations, we evaluate the stable size as a function of cohesion under the constant friction angle 32 degree. The result shows that if the size is 1.24, the necessary cohesion required is 90000 Pa; otherwise, the value dramatically increases up to 1e6 Pa. This technique is robust; therefore, once we obtain accurate physical parameters from more detail observations, our methodology will be able to give stronger constraints (216) Kleopatra, as well as other rubble pile asteroids.

Automated Droplet Manipulation Using Closed-Loop Axisymmetric Drop Shape Analysis.

PubMed

Yu, Kyle; Yang, Jinlong; Zuo, Yi Y

2016-05-17

Droplet manipulation plays an important role in a wide range of scientific and industrial applications, such as synthesis of thin-film materials, control of interfacial reactions, and operation of digital microfluidics. Compared to micron-sized droplets, which are commonly considered as spherical beads, millimeter-sized droplets are generally deformable by gravity, thus introducing nonlinearity into control of droplet properties. Such a nonlinear drop shape effect is especially crucial for droplet manipulation, even for small droplets, at the presence of surfactants. In this paper, we have developed a novel closed-loop axisymmetric drop shape analysis (ADSA), integrated into a constrained drop surfactometer (CDS), for manipulating millimeter-sized droplets. The closed-loop ADSA generalizes applications of the traditional drop shape analysis from a surface tension measurement methodology to a sophisticated tool for manipulating droplets in real time. We have demonstrated the feasibility and advantages of the closed-loop ADSA in three applications, including control of drop volume by automatically compensating natural evaporation, precise control of surface area variations for high-fidelity biophysical simulations of natural pulmonary surfactant, and steady control of surface pressure for in situ Langmuir-Blodgett transfer from droplets. All these applications have demonstrated the accuracy, versatility, applicability, and automation of this new ADSA-based droplet manipulation technique. Combining with CDS, the closed-loop ADSA holds great promise for advancing droplet manipulation in a variety of material and surface science applications, such as thin-film fabrication, self-assembly, and biophysical study of pulmonary surfactant.

Deconstructing cartilage shape and size into contributions from embryogenesis, metamorphosis, and tadpole and frog growth.

PubMed

Rose, Christopher S; Murawinski, Danny; Horne, Virginia

2015-06-01

Understanding skeletal diversification involves knowing not only how skeletal rudiments are shaped embryonically, but also how skeletal shape changes throughout life. The pharyngeal arch (PA) skeleton of metamorphosing amphibians persists largely as cartilage and undergoes two phases of development (embryogenesis and metamorphosis) and two phases of growth (larval and post-metamorphic). Though embryogenesis and metamorphosis produce species-specific features of PA cartilage shape, the extents to which shape and size change during growth and metamorphosis remain unaddressed. This study uses allometric equations and thin-plate spline, relative warp and elliptic Fourier analyses to describe shape and size trajectories for the ventral PA cartilages of the frog Xenopus laevis in tadpole and frog growth and metamorphosis. Cartilage sizes scale negatively with body size in both growth phases and cartilage shapes scale isometrically or close to it. This implies that most species-specific aspects of cartilage shape arise in embryogenesis and metamorphosis. Contributions from growth are limited to minor changes in lower jaw (LJ) curvature that produce relative gape narrowing and widening in tadpoles and frogs, respectively, and most cartilages becoming relatively thinner. Metamorphosis involves previously unreported decreases in cartilage size as well as changes in cartilage shape. The LJ becomes slightly longer, narrower and more curved, and the adult ceratohyal emerges from deep within the resorbing tadpole ceratohyal. This contrast in shape and size changes suggests a fundamental difference in the underlying cellular pathways. The observation that variation in PA cartilage shape decreases with tadpole growth supports the hypothesis that isometric growth is required for the metamorphic remodeling of PA cartilages. It also supports the existence of shape-regulating mechanisms that are specific to PA cartilages and that resist local adaptation and phenotypic plasticity. © 2015 Anatomical Society.

Deconstructing cartilage shape and size into contributions from embryogenesis, metamorphosis, and tadpole and frog growth

PubMed Central

Rose, Christopher S; Murawinski, Danny; Horne, Virginia

2015-01-01

Understanding skeletal diversification involves knowing not only how skeletal rudiments are shaped embryonically, but also how skeletal shape changes throughout life. The pharyngeal arch (PA) skeleton of metamorphosing amphibians persists largely as cartilage and undergoes two phases of development (embryogenesis and metamorphosis) and two phases of growth (larval and post-metamorphic). Though embryogenesis and metamorphosis produce species-specific features of PA cartilage shape, the extents to which shape and size change during growth and metamorphosis remain unaddressed. This study uses allometric equations and thin-plate spline, relative warp and elliptic Fourier analyses to describe shape and size trajectories for the ventral PA cartilages of the frog Xenopus laevis in tadpole and frog growth and metamorphosis. Cartilage sizes scale negatively with body size in both growth phases and cartilage shapes scale isometrically or close to it. This implies that most species-specific aspects of cartilage shape arise in embryogenesis and metamorphosis. Contributions from growth are limited to minor changes in lower jaw (LJ) curvature that produce relative gape narrowing and widening in tadpoles and frogs, respectively, and most cartilages becoming relatively thinner. Metamorphosis involves previously unreported decreases in cartilage size as well as changes in cartilage shape. The LJ becomes slightly longer, narrower and more curved, and the adult ceratohyal emerges from deep within the resorbing tadpole ceratohyal. This contrast in shape and size changes suggests a fundamental difference in the underlying cellular pathways. The observation that variation in PA cartilage shape decreases with tadpole growth supports the hypothesis that isometric growth is required for the metamorphic remodeling of PA cartilages. It also supports the existence of shape-regulating mechanisms that are specific to PA cartilages and that resist local adaptation and phenotypic plasticity. PMID:25913729

The Microwave Properties of Simulated Melting Precipitation Particles: Sensitivity to Initial Melting

NASA Technical Reports Server (NTRS)

Johnson, B. T.; Olson, W. S.; Skofronick-Jackson, G.

2016-01-01

A simplified approach is presented for assessing the microwave response to the initial melting of realistically shaped ice particles. This paper is divided into two parts: (1) a description of the Single Particle Melting Model (SPMM), a heuristic melting simulation for ice-phase precipitation particles of any shape or size (SPMM is applied to two simulated aggregate snow particles, simulating melting up to 0.15 melt fraction by mass), and (2) the computation of the single-particle microwave scattering and extinction properties of these hydrometeors, using the discrete dipole approximation (via DDSCAT), at the following selected frequencies: 13.4, 35.6, and 94.0GHz for radar applications and 89, 165.0, and 183.31GHz for radiometer applications. These selected frequencies are consistent with current microwave remote-sensing platforms, such as CloudSat and the Global Precipitation Measurement (GPM) mission. Comparisons with calculations using variable-density spheres indicate significant deviations in scattering and extinction properties throughout the initial range of melting (liquid volume fractions less than 0.15). Integration of the single-particle properties over an exponential particle size distribution provides additional insight into idealized radar reflectivity and passive microwave brightness temperature sensitivity to variations in size/mass, shape, melt fraction, and particle orientation.

Gravity and the mechanics of dike intrusion

NASA Astrophysics Data System (ADS)

Townsend, M.

2017-12-01

Dikes are a diverse yet ubiquitous feature of terrestrial volcanic and magmatic settings, ranging in size from decimeter-thick aplite dikes in silicic plutons, to meters-thick dikes at basaltic shield volcanoes and rift zones, to 100-meter-thick "giant" dikes in swarms that can exceed over 2000 km in length. Dike profiles may be planar or curved, elliptical or teardrop-shaped, and blunt or tapered at the tips. The variety of size, shape, composition, and intrusion environment is in contrast with the ubiquitous observation that dikes tend to be vertically inclined, emanate from central reservoirs, and propagate laterally for distances that are 10 to over 100 times their height. In this talk, I will briefly review the geological and geophysical observations of dike geometry and propagation directions. These data motivate a 2D mechanical model for vertical dikes in which the primary loading is due to gravity. Using this model, I will explore fundamental relationships between density structure within the magma and surrounding crust, driving pressure, topographic and tectonic loading, and the size, shape, and depth at which dikes become vertically stable such that subsequent propagation is lateral. Modeling results highlight a dual effect of gravity, as both a source of diversity in stable dike geometries and as a robust mechanism for trapping dikes in the subsurface.

Biological synthesis of triangular gold nanoprisms

NASA Astrophysics Data System (ADS)

Shankar, S. Shiv; Rai, Akhilesh; Ankamwar, Balaprasad; Singh, Amit; Ahmad, Absar; Sastry, Murali

2004-07-01

The optoelectronic and physicochemical properties of nanoscale matter are a strong function of particle size. Nanoparticle shape also contributes significantly to modulating their electronic properties. Several shapes ranging from rods to wires to plates to teardrop structures may be obtained by chemical methods; triangular nanoparticles have been synthesized by using a seeded growth process. Here, we report the discovery that the extract from the lemongrass plant, when reacted with aqueous chloroaurate ions, yields a high percentage of thin, flat, single-crystalline gold nanotriangles. The nanotriangles seem to grow by a process involving rapid reduction, assembly and room-temperature sintering of 'liquid-like' spherical gold nanoparticles. The anisotropy in nanoparticle shape results in large near-infrared absorption by the particles, and highly anisotropic electron transport in films of the nanotriangles.

Beyond body size: muscle biochemistry and body shape explain ontogenetic variation of anti-predatory behaviour in the lizard Salvator merianae.

PubMed

de Barros, Fábio Cury; de Carvalho, José Eduardo; Abe, Augusto Shinya; Kohlsdorf, Tiana

2016-06-01

Anti-predatory behaviour evolves under the strong action of natural selection because the success of individuals avoiding predation essentially defines their fitness. Choice of anti-predatory strategies is defined by prey characteristics as well as environmental temperature. An additional dimension often relegated in this multilevel equation is the ontogenetic component. In the tegu Salvator merianae, adults run away from predators at high temperatures but prefer fighting when it is cold, whereas juveniles exhibit the same flight strategy within a wide thermal range. Here, we integrate physiology and morphology to understand ontogenetic variation in the temperature-dependent shift of anti-predatory behaviour in these lizards. We compiled data for body shape and size, and quantified enzyme activity in hindlimb and head muscles, testing the hypothesis that morphophysiological models explain ontogenetic variation in behavioural associations. Our prediction is that juveniles exhibit body shape and muscle biochemistry that enhance flight strategies. We identified biochemical differences between muscles mainly in the LDH:CS ratio, whereby hindlimb muscles were more glycolytic than the jaw musculature. Juveniles, which often use evasive strategies to avoid predation, have more glycolytic hindlimb muscles and are much smaller when compared with adults 1-2 years old. Ontogenetic differences in body shape were identified but marginally contributed to behavioural variation between juvenile and adult tegus, and variation in anti-predatory behaviour in these lizards resides mainly in associations between body size and muscle biochemistry. Our results are discussed in the ecological context of predator avoidance by individuals differing in body size living at temperature-variable environments, where restrictions imposed by the cold could be compensated by specific phenotypes. © 2016. Published by The Company of Biologists Ltd.

Crustal dynamics project site selection criteria

NASA Technical Reports Server (NTRS)

Allenby, R.

1983-01-01

The criteria for selecting site locations and constructing observing pads and monuments for the Mobile VLB1 and the satellite laser ranging systems used in the NASA/GSFC Crustal Dynamics Project are discussed. Gross system characteristics (size, shape, weight, power requirement, foot prints, etc.) are given for the Moblas, MV-1 through 3, TLRS-1 through 4 and Series instruments.

Monel-shot and screen regenerators

NASA Technical Reports Server (NTRS)

Browning, C. W.

1974-01-01

Monel has been found to be ideal material for matrix of regenerators operating in temperature range of 325 K to 50 K. Two best shapes are as spheres or as wire mesh. For given size of regenerator, spherical shots are preferable for low-temperature operation. At high temperatures, mesh would be superior by virtue of its lower flow resistance.

Dip TIPS as a Facile and Versatile Method for Fabrication of Polymer Foams with Controlled Shape, Size and Pore Architecture for Bioengineering Applications

PubMed Central

Kasoju, Naresh; Kubies, Dana; Kumorek, Marta M.; Kříž, Jan; Fábryová, Eva; Machová, Lud'ka; Kovářová, Jana; Rypáček, František

2014-01-01

The porous polymer foams act as a template for neotissuegenesis in tissue engineering, and, as a reservoir for cell transplants such as pancreatic islets while simultaneously providing a functional interface with the host body. The fabrication of foams with the controlled shape, size and pore structure is of prime importance in various bioengineering applications. To this end, here we demonstrate a thermally induced phase separation (TIPS) based facile process for the fabrication of polymer foams with a controlled architecture. The setup comprises of a metallic template bar (T), a metallic conducting block (C) and a non-metallic reservoir tube (R), connected in sequence T-C-R. The process hereinafter termed as Dip TIPS, involves the dipping of the T-bar into a polymer solution, followed by filling of the R-tube with a freezing mixture to induce the phase separation of a polymer solution in the immediate vicinity of T-bar; Subsequent free-drying or freeze-extraction steps produced the polymer foams. An easy exchange of the T-bar of a spherical or rectangular shape allowed the fabrication of tubular, open- capsular and flat-sheet shaped foams. A mere change in the quenching time produced the foams with a thickness ranging from hundreds of microns to several millimeters. And, the pore size was conveniently controlled by varying either the polymer concentration or the quenching temperature. Subsequent in vivo studies in brown Norway rats for 4-weeks demonstrated the guided cell infiltration and homogenous cell distribution through the polymer matrix, without any fibrous capsule and necrotic core. In conclusion, the results show the “Dip TIPS” as a facile and adaptable process for the fabrication of anisotropic channeled porous polymer foams of various shapes and sizes for potential applications in tissue engineering, cell transplantation and other related fields. PMID:25275373

Distribution and predictors of wing shape and size variability in three sister species of solitary bees

PubMed Central

Prunier, Jérôme G.; Dewulf, Alexandre; Kuhlmann, Michael; Michez, Denis

2017-01-01

Morphological traits can be highly variable over time in a particular geographical area. Different selective pressures shape those traits, which is crucial in evolutionary biology. Among these traits, insect wing morphometry has already been widely used to describe phenotypic variability at the inter-specific level. On the contrary, fewer studies have focused on intra-specific wing morphometric variability. Yet, such investigations are relevant to study potential convergences of variation that could highlight micro-evolutionary processes. The recent sampling and sequencing of three solitary bees of the genus Melitta across their entire species range provides an excellent opportunity to jointly analyse genetic and morphometric variability. In the present study, we first aim to analyse the spatial distribution of the wing shape and centroid size (used as a proxy for body size) variability. Secondly, we aim to test different potential predictors of this variability at both the intra- and inter-population levels, which includes genetic variability, but also geographic locations and distances, elevation, annual mean temperature and precipitation. The comparison of spatial distribution of intra-population morphometric diversity does not reveal any convergent pattern between species, thus undermining the assumption of a potential local and selective adaptation at the population level. Regarding intra-specific wing shape differentiation, our results reveal that some tested predictors, such as geographic and genetic distances, are associated with a significant correlation for some species. However, none of these predictors are systematically identified for the three species as an important factor that could explain the intra-specific morphometric variability. As a conclusion, for the three solitary bee species and at the scale of this study, our results clearly tend to discard the assumption of the existence of a common pattern of intra-specific signal/structure within the intra-specific wing shape and body size variability. PMID:28273178

Dip TIPS as a facile and versatile method for fabrication of polymer foams with controlled shape, size and pore architecture for bioengineering applications.

PubMed

Kasoju, Naresh; Kubies, Dana; Kumorek, Marta M; Kříž, Jan; Fábryová, Eva; Machová, Lud'ka; Kovářová, Jana; Rypáček, František

2014-01-01

The porous polymer foams act as a template for neotissuegenesis in tissue engineering, and, as a reservoir for cell transplants such as pancreatic islets while simultaneously providing a functional interface with the host body. The fabrication of foams with the controlled shape, size and pore structure is of prime importance in various bioengineering applications. To this end, here we demonstrate a thermally induced phase separation (TIPS) based facile process for the fabrication of polymer foams with a controlled architecture. The setup comprises of a metallic template bar (T), a metallic conducting block (C) and a non-metallic reservoir tube (R), connected in sequence T-C-R. The process hereinafter termed as Dip TIPS, involves the dipping of the T-bar into a polymer solution, followed by filling of the R-tube with a freezing mixture to induce the phase separation of a polymer solution in the immediate vicinity of T-bar; Subsequent free-drying or freeze-extraction steps produced the polymer foams. An easy exchange of the T-bar of a spherical or rectangular shape allowed the fabrication of tubular, open- capsular and flat-sheet shaped foams. A mere change in the quenching time produced the foams with a thickness ranging from hundreds of microns to several millimeters. And, the pore size was conveniently controlled by varying either the polymer concentration or the quenching temperature. Subsequent in vivo studies in brown Norway rats for 4-weeks demonstrated the guided cell infiltration and homogenous cell distribution through the polymer matrix, without any fibrous capsule and necrotic core. In conclusion, the results show the "Dip TIPS" as a facile and adaptable process for the fabrication of anisotropic channeled porous polymer foams of various shapes and sizes for potential applications in tissue engineering, cell transplantation and other related fields.

Preliminary Investigation in the NACA Low-Turbulence Tunnel of Low-drag Airfoil Sections Suitable for Admitting Air at the Leading Edge

NASA Technical Reports Server (NTRS)

von Doenhoff, Albert E.; Horton, Elmer A.

1942-01-01

An investigation was carried out in the NACA low-turbulence tunnel to develop low-drag airfoil sections suitable for admitting air at the leading edge. A thickness distribution having the desired type of pressure distribution was found from tests of a flexible model. Other airfoil shapes were derived from this original shape by varying the thickness, the camper, the leading-edge radius, and the size of the leading-edge opening. Data are presented giving the characteristics of the airfoil shapes in the range of lift coefficients for high-speed and cruising flight. Shapes have been developed which show no substantial increases in drag over that of the same position along the chord. Many of these shapes appear to have higher critical compressibility speeds than plain airfoils of the same thickness. Low-drag airfoil sections have been developed with openings in the leading edge as large as 41.5 percent of the maximum thickness. The range of lift coefficients for low drag in several cases is nearly as large as that of the corresponding plain airfoil sections. Preliminary measurements of maximum lift characteristics indicate that nose-opening sections of the type herein considered may not produce any marked effects on the maximum lift coefficient.

Spinal cord evolution in early Homo.

PubMed

Meyer, Marc R; Haeusler, Martin

2015-11-01

The discovery at Nariokotome of the Homo erectus skeleton KNM-WT 15000, with a narrow spinal canal, seemed to show that this relatively large-brained hominin retained the primitive spinal cord size of African apes and that brain size expansion preceded postcranial neurological evolution. Here we compare the size and shape of the KNM-WT 15000 spinal canal with modern and fossil taxa including H. erectus from Dmanisi, Homo antecessor, the European middle Pleistocene hominins from Sima de los Huesos, and Pan troglodytes. In terms of shape and absolute and relative size of the spinal canal, we find all of the Dmanisi and most of the vertebrae of KNM-WT 15000 are within the human range of variation except for the C7, T2, and T3 of KNM-WT 15000, which are constricted, suggesting spinal stenosis. While additional fossils might definitively indicate whether H. erectus had evolved a human-like enlarged spinal canal, the evidence from the Dmanisi spinal canal and the unaffected levels of KNM-WT 15000 show that unlike Australopithecus, H. erectus had a spinal canal size and shape equivalent to that of modern humans. Subadult status is unlikely to affect our results, as spinal canal growth is complete in both individuals. We contest the notion that vertebrae yield information about respiratory control or language evolution, but suggest that, like H. antecessor and European middle Pleistocene hominins from Sima de los Huesos, early Homo possessed a postcranial neurological endowment roughly commensurate to modern humans, with implications for neurological, structural, and vascular improvements over Pan and Australopithecus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Protection of obstetric dimensions in a small-bodied human sample.

PubMed

Kurki, Helen K

2007-08-01

In human females, the bony pelvis must find a balance between being small (narrow) for efficient bipedal locomotion, and being large to accommodate a relatively large newborn. It has been shown that within a given population, taller/larger-bodied women have larger pelvic canals. This study investigates whether in a population where small body size is the norm, pelvic geometry (size and shape), on average, shows accommodation to protect the obstetric canal. Osteometric data were collected from the pelves, femora, and clavicles (body size indicators) of adult skeletons representing a range of adult body size. Samples include Holocene Later Stone Age (LSA) foragers from southern Africa (n = 28 females, 31 males), Portuguese from the Coimbra-identified skeletal collection (CISC) (n = 40 females, 40 males) and European-Americans from the Hamann-Todd osteological collection (H-T) (n = 40 females, 40 males). Patterns of sexual dimorphism are similar in the samples. Univariate and multivariate analyses of raw and Mosimann shape-variables indicate that compared to the CISC and H-T females, the LSA females have relatively large midplane and outlet canal planes (particularly posterior and A-P lengths). The LSA males also follow this pattern, although with absolutely smaller pelves in multivariate space. The CISC females, who have equally small stature, but larger body mass, do not show the same type of pelvic canal size and shape accommodation. The results suggest that adaptive allometric modeling in at least some small-bodied populations protects the obstetric canal. These findings support the use of population-specific attributes in the clinical evaluation of obstetric risk. (c) 2007 Wiley-Liss, Inc.

Equipotential doming in flooded circular basins on the moon

NASA Technical Reports Server (NTRS)

Roth, L. E.; Elachi, C.; Phillips, R. J.

1977-01-01

A procedure is presented that permits determination of the shape of the gravity field due to an arbitrary mass configuration with circular symmetry. The procedure is used to model the shape of the field associated with the lunar circular basins. The mean slopes of the equipotential surfaces generated by a superisostatic deposit corresponding to a near-surface Crisium-size mascon are calculated to fall within the range from 1:700 to 1:1000; those generated by a mantle rebound of the same excess mass, at 60 km below the lunar surface, cluster around the value of 1:1500.

Nano-polarization-converter based on magnetic plasmon resonance excitation in an L-shaped slot antenna.

PubMed

Yang, Jing; Zhang, Jiasen

2013-04-08

We propose a nano-polarization-converter made of a resonant L-shaped slot antenna in a gold film and study its optical properties using the finite-difference time-domain method. Phase retardation between the fast and slow axes of the nano-polarization-converter originates from the simultaneous excitation of both single-surface first-order magnetic plasmon resonance mode and second-order magnetic plasmon resonance mode at the working wavelength. By adjusting the size of the slot antenna, which is still much smaller than the wavelength, the working wavelength can be tuned within a large wavelength range.

3D granulometry: grain-scale shape and size distribution from point cloud dataset of river environments

NASA Astrophysics Data System (ADS)

Steer, Philippe; Lague, Dimitri; Gourdon, Aurélie; Croissant, Thomas; Crave, Alain

2016-04-01

The grain-scale morphology of river sediments and their size distribution are important factors controlling the efficiency of fluvial erosion and transport. In turn, constraining the spatial evolution of these two metrics offer deep insights on the dynamics of river erosion and sediment transport from hillslopes to the sea. However, the size distribution of river sediments is generally assessed using statistically-biased field measurements and determining the grain-scale shape of river sediments remains a real challenge in geomorphology. Here we determine, with new methodological approaches based on the segmentation and geomorphological fitting of 3D point cloud dataset, the size distribution and grain-scale shape of sediments located in river environments. Point cloud segmentation is performed using either machine-learning algorithms or geometrical criterion, such as local plan fitting or curvature analysis. Once the grains are individualized into several sub-clouds, each grain-scale morphology is determined using a 3D geometrical fitting algorithm applied on the sub-cloud. If different geometrical models can be conceived and tested, only ellipsoidal models were used in this study. A phase of results checking is then performed to remove grains showing a best-fitting model with a low level of confidence. The main benefits of this automatic method are that it provides 1) an un-biased estimate of grain-size distribution on a large range of scales, from centimeter to tens of meters; 2) access to a very large number of data, only limited by the number of grains in the point-cloud dataset; 3) access to the 3D morphology of grains, in turn allowing to develop new metrics characterizing the size and shape of grains. The main limit of this method is that it is only able to detect grains with a characteristic size greater than the resolution of the point cloud. This new 3D granulometric method is then applied to river terraces both in the Poerua catchment in New-Zealand and along the Laonong river in Taiwan, which point clouds were obtained using both terrestrial lidar scanning and structure from motion photogrammetry.

The Effect of Cage Shape on Nanoparticle-Based Drug Carriers: Anticancer Drug Release and Efficacy via Receptor Blockade Using Dextran-Coated Iron Oxide Nanocages.

PubMed

Rampersaud, Sham; Fang, Justin; Wei, Zengyan; Fabijanic, Kristina; Silver, Stefan; Jaikaran, Trisha; Ruiz, Yuleisy; Houssou, Murielle; Yin, Zhiwei; Zheng, Shengping; Hashimoto, Ayako; Hoshino, Ayuko; Lyden, David; Mahajan, Shahana; Matsui, Hiroshi

2016-12-14

Although a range of nanoparticles have been developed as drug delivery systems in cancer therapeutics, this approach faces several important challenges concerning nanocarrier circulation, clearance, and penetration. The impact of reducing nanoparticle size on penetration through leaky blood vessels around tumor microenvironments via enhanced permeability and retention (EPR) effect has been extensively examined. Recent research has also investigated the effect of nanoparticle shape on circulation and target binding affinity. However, how nanoparticle shape affects drug release and therapeutic efficacy has not been previously explored. Here, we compared the drug release and efficacy of iron oxide nanoparticles possessing either a cage shape (IO-NCage) or a solid spherical shape (IO-NSP). Riluzole cytotoxicity against metastatic cancer cells was enhanced 3-fold with IO-NCage. The shape of nanoparticles (or nanocages) affected the drug release point and cellular internalization, which in turn influenced drug efficacy. Our study provides evidence that the shape of iron oxide nanoparticles has a significant impact on drug release and efficacy.

Complexity of Fit, with Application to Space Suits

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar; Benson, Elizabeth

2009-01-01

Although fitting a garment is often considered more of an art than a science, experts suggest that a subjectively poor fit is a symptom of inappropriate ease, the space between the wearer and the garment. The condition of poor suit fit is a unique problem for the space program and it can be attributed primarily to: a) NASA s policy to accommodate a wide variety of people (males and females from 1st to 99th percentile range and with various shapes and sizes) and b) its requirement to deploy a minimum number of suit sizes for logistical reasons. These factors make the space suit fit difficult to assess, where a wide range of people must be fit by the minimum possible number of suits, and yet, fit is crucial for operability and safety. Existing simplistic sizing scheme do not account for wide variations in shape within a diverse population with very limited sizing options. The complex issue of fit has been addressed by a variety of methods, many of which have been developed by the military, which has always had a keen interest in fitting its diverse population but with a multitude of sizing options. The space program has significantly less sizing options, so a combination of these advanced methods should be used to optimize space suit size and assess space suit fit. Multivariate methods can be used to develop sizing schemes that better reflect the wearer population, and integrated sizing systems can form a compromise between fitting men and women. Range of motion and operability testing can be combined with subjective feedback to provide a comprehensive evaluation of fit. The amount of ease can be tailored using these methods, to provide enough extra room where it is needed, without compromising mobility and comfort. This paper discusses the problem of fit in one of its most challenging applications: providing a safe and comfortable spacesuit that will protect its wearer from the extreme environment of space. It will discuss the challenges and necessity of closely fitting its potential wearers, a group of people from a broad spectrum of the population, and will detail some of the methods that can be employed to ensure and validate a good fit.

Size-Dependent Coherent-Phonon Plasmon Modulation and Deformation Characterization in Gold Bipyramids and Nanojavelins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirschner, Matthew S.; Lethiec, Clotilde M.; Lin, Xiao-Min

2016-04-04

Localized surface plasmon resonances (LSPRs) arising from metallic nanoparticles offer an array of prospective applications that range from chemical sensing to biotherapies. Bipyramidal particles exhibit particularly narrow ensemble LSPR resonances that reflect small dispersity of size and shape but until recently were only synthetically accessible over a limited range of sizes with corresponding aspect ratios. Narrow size dispersion offers the opportunity to examine ensemble dynamical phenomena such as coherent phonons that induce periodic oscillations of the LSPR energy. Here, we characterize transient optical behavior of a large range of gold bipyramid sizes, as well as higher aspect ratio nanojavelin ensemblesmore » with specific attention to the lowest-order acoustic phonon mode of these nanoparticles. We report coherent phonon-driven oscillations of the LSPR position for particles with resonances spanning 670 to 1330 nm. Nanojavelins were shown to behave similarly to bipyramids but offer the prospect of separate control over LSPR energy and coherent phonon oscillation period. We develop a new methodology for quantitatively measuring mechanical expansion caused by photogenerated coherent phonons. Using this method, we find an elongation of approximately 1% per photon absorbed per unit cell and that particle expansion along the lowest frequency acoustic phonon mode is linearly proportional to excitation fluence for the fluence range studied. These characterizations provide insight regarding means to manipulate phonon period and transient mechanical deformation.« less

A novel method of creation capillary structures in metal parts based on using selective laser melting methid of 3D printing technology and surface roughness

NASA Astrophysics Data System (ADS)

Ivanov, Roman A.; Melkikh, Alexey V.

2017-09-01

It has been experimentally proved that it is possible to produce a metal capillary structure with significant capillary action and free shape configuration using selective laser melting. Capillaries are created by dividing the solid detail volume into micro-sized parallel walls with roughness as a result of SLM 3D printing. Experiments are conducted on aluminum powder with particle size in the range of 10-40 µm (,) and distances in 3D model between surfaces incapillary generation zone in the range of 50-200 µm. It is showed that products produced from model with 100 µm gaps have the greatest efficiency of fluid lifting as a result of obtaining stable arrays of capillaries of 20-40 µm in size. Change in the direction of (growing) printingthe product doesn't significantly influence on capillary geometry, but it affects on safety of the structure.

The model of the long-range effect in solids: Evolution of structure, clusters of internal boundaries, and their statistical descriptors

NASA Astrophysics Data System (ADS)

Herega, Alexander; Sukhanov, Volodymyr; Vyrovoy, Valery

2017-12-01

It is known that the multifocal mechanism of genesis of structure of heterogeneous materials provokes intensive formation of internal boundaries. In the present papers, the dependence of the structure and properties of material on the characteristic size and shape, the number and size distribution, and the character of interaction of individual internal boundaries and their clusters is studied. The limitation on the applicability of the material damage coefficient is established; the effective information descriptor of internal boundaries is proposed. An idea of the effect of long-range interaction in irradiated solids on the realization of the second-order phase transition is introduced; a phenomenological percolation model of the effect is proposed.

The grain size dependency of vesicular particle shapes strongly affects the drag of particles. First results from microtomography investigations of Campi Flegrei fallout deposits

NASA Astrophysics Data System (ADS)

Mele, Daniela; Dioguardi, Fabio

2018-03-01

Acknowledging the grain size dependency of shape is important in volcanology, in particular when dealing with tephra produced and emplaced during and after explosive volcanic eruptions. A systematic measurement of the tridimensional shape of vesicular pyroclasts of Campi Flegrei fallout deposits (Agnano-Monte Spina, Astroni 6 and Averno 2 eruptions) varying in size from 8.00 to 0.016 mm has been carried out by means of X-Ray Microtomography. Data show that particle shape changes with size, especially for juvenile vesicular clasts, since it is dependent on the distribution and size of vesicles that contour the external clast outline. Two drag laws that include sphericity in the formula were used for estimating the dependency of settling velocity on shape. Results demonstrate that it is not appropriate to assume a size-independent shape for vesicular particles, in contrast with the approach commonly employed when simulating the ash dispersion in the atmosphere.

Identification of different shapes, colors and sizes of standard oral dosage forms in diabetes type 2 patients-A pilot study.

PubMed

Stegemann, Sven; Riedl, Regina; Sourij, Harald

2017-01-30

The clear identification of drug products by the patients is essential for a safe and effective medication management. In order to understand the impact of shape, size and color on medication identification a study was performed in subjects with type 2 diabetes mellitus (T2D). Ten model drugs differentiated by shape, size and color were evaluated using a mixed method of medication schedule preparation by the participants followed by a semi-structured interview. Detection times were fastest for the large round tablet shape and the bi-chromatic forms. Larger size was easier to identify than the smaller sizes except for the bi-chromatic forms. The shape was the major source of errors, followed by the size and the color dimension. The results from this study suggests that color as a single dimension are perceived more effectively by subjects with T2D compared to shape and size, which requires a more demanding processing of three dimension and is dependent on the perspective. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation of artificial kidney stones of reproducible size, shape, and mass by precision injection molding.

PubMed

Carey, Robert I; Kyle, Christopher C; Carey, Donna L; Leveillee, Raymond J

2008-01-01

To prepare artificial kidney stones of defined shape, size, mass, and material composition via precision injection molding of Ultracal 30 cement slurries into an inexpensive biodegradable mold. A calcium alginate and silica-based mold was used to prepare casts of varying shapes in a reproducible manner. Ultracal 30 cement slurries mixed 1:1 with water were injected into these casts and allowed to harden. The artificial stones were recovered and their physical properties determined. Ex-vivo and in-vivo responses to holmium laser lithotripsy were examined. Spheres, half spheres, cylinders, cubes, tapered conical structures, and flat angulated structures were prepared with high precision without post-molding manipulations. Large spheres of average mass 0.661 g (+/- 0.037), small spheres of average mass 0.046 g (+/- 0.0026), and hexagons of average mass 0.752 g (+/- 0.0180) were found to have densities (1610-1687 kg/m(3)) within the expected range for Ultracal 30 cement stones. Ex-vivo holmium laser lithotripsy of small spheres in saline showed uniformly reproducible efficiencies of comminution. Implantation of a tapered conical stone into the ureter of a porcine model demonstrated stone comminution in vivo consistent with that seen in the ex-vivo models. We present an environmentally safe, technically simple procedure for the formation of artificial kidney stones of predetermined size and shape. The technique does not require the use of hazardous solvents or postprocedural processing of the stones. These stones are intended for use in standardized experiments of lithotripsy efficiency in which the shape of the stone as well as the mass can be predetermined and precisely controlled.

Morphological variation in Sarracenia purpurea (Sarraceniaceae): geographic, environmental, and taxonomic correlates.

PubMed

Ellison, Aaron M; Buckley, Hannah L; Miller, Thomas E; Gotelli, Nicholas J

2004-11-01

Geographic variation in morphology reflects phenotypic responses to environmental gradients and evolutionary history of populations and species and may indicate local or regional changes in environmental conditions. The pitcher plant (Sarracenia purpurea) illustrates these principles. At local scales, its morphology reflects nutrient availability. At points along its broad geographic range (from Florida to northern Canada) morphology has been used to distinguish subspecies and varieties, but there has been no detailed study of the continuum of morphological variation across this entire range. Patterns of morphological variation in S. purpurea were characterized as a function of climatic and environmental conditions at 39 sites spanning its range. Differences in pitcher size and shape were strongly correlated with temperature, annual precipitation, and availability of ammonium and calcium in peat pore water. Pitcher shape (lip width, mouth diameter, and pitcher width) in Florida panhandle populations differed significantly from pitcher shape of all other populations, even after accounting for environmental correlations. In contrast, the northern and southern subspecies of S. purpurea (the latter exclusive of the Florida panhandle populations) cannot be distinguished based on these morphological measurements alone. These results support a recent proposal that identifies the Florida populations as a distinct species, Sarracenia rosea.

The determination of the operating range of a twin-grip control yoke through biomechanical means

NASA Technical Reports Server (NTRS)

Gaertner, K. P.

1978-01-01

A twin-grip control yoke was designed as an ergonomic case study that allows dual axis control inputs, both axes being rotational. Inputs are effected by rotating the grips. How the handles were designed with respect to their shape and size and how the angular range of the control yoke in both rotational axes was evaluated. The control yoke which requires two-hand operation was tested to determine its operating range. The intention of this investigation was to find out the optimal form of the control yoke and the maximum permissible range in both rotating axes. In these experiments controls had no spring resistance.

Size-controlled synthesis of nanocrystalline CdSe thin films by inert gas condensation

NASA Astrophysics Data System (ADS)

Sharma, Jeewan; Singh, Randhir; Kumar, Akshay; Singh, Tejbir; Agrawal, Paras; Thakur, Anup

2018-02-01

Size, shape and structure are considered to have significant influence on various properties of semiconducting nanomaterials. Different properties of these materials can be tailored by controlling the size. Size-controlled CdSe crystallites ranging from ˜ 04 to 95 nm were deposited by inert gas-condensation technique (IGC). In IGC method, by controlling the inert gas pressure in the condensation chamber and the substrate temperature or both, it was possible to produce nanoparticles with desired size. Structure and crystallite size of CdSe thin films were determined from Hall-Williamson method using X-ray diffraction data. The composition of CdSe samples was estimated by X-ray microanalysis. It was confirmed that CdSe thin film with different nanometer range crystallite sizes were synthesized with this technique, depending upon the synthesis conditions. The phase of deposited CdSe thin films also depend upon deposition conditions and cubic to hexagonal phase transition was observed with increase in substrate temperature. The effect of crystallite size on optical and electrical properties of these films was also studied. The crystallite size affects the optical band gap, electrical conductivity and mobility activation of nanocrystalline CdSe thin films. Mobility activation study suggested that there is a quasi-continuous linear distribution of three different trap levels below the conduction band.

Flexible wire-shaped strain sensor from cotton thread for human health and motion detection.

PubMed

Li, Yuan-Qing; Huang, Pei; Zhu, Wei-Bin; Fu, Shao-Yun; Hu, Ning; Liao, Kin

2017-03-21

In this work, a wire-shaped flexible strain sensor was fabricated by encapsulating conductive carbon thread (CT) with polydimethylsiloxane (PDMS) elastomer. The key strain sensitive material, CT, was prepared by pyrolysing cotton thread in N 2 atmosphere. The CT/PDMS composite wire shows a typical piezo-resistive behavior with high strain sensitivity. The gauge factors (GF) calculated at low strain of 0-4% and high strain of 8-10% are 8.7 and 18.5, respectively, which are much higher than that of the traditional metallic strain sensor (GF around 2). The wire-shaped CT/PDMS composite sensor shows excellent response to cyclic tensile loading within the strain range of 0-10%, the frequency range of 0.01-10 Hz, to up to 2000 cycles. The potential of the wire senor as wearable strain sensor is demonstrated by the finger motion and blood pulse monitoring. Featured by the low costs of cotton wire and PDMS resin, the simple structure and fabrication technique, as well as high performance with miniaturized size, the wire-shaped sensor based on CT/PDMS composite is believed to have a great potential for application in wearable electronics for human health and motion monitoring.

A Monte Carlo model for 3D grain evolution during welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodgers, Theron M.; Mitchell, John A.; Tikare, Veena

Welding is one of the most wide-spread processes used in metal joining. However, there are currently no open-source software implementations for the simulation of microstructural evolution during a weld pass. Here we describe a Potts Monte Carlo based model implemented in the SPPARKS kinetic Monte Carlo computational framework. The model simulates melting, solidification and solid-state microstructural evolution of material in the fusion and heat-affected zones of a weld. The model does not simulate thermal behavior, but rather utilizes user input parameters to specify weld pool and heat-affect zone properties. Weld pool shapes are specified by Bezier curves, which allow formore » the specification of a wide range of pool shapes. Pool shapes can range from narrow and deep to wide and shallow representing different fluid flow conditions within the pool. Surrounding temperature gradients are calculated with the aide of a closest point projection algorithm. Furthermore, the model also allows simulation of pulsed power welding through time-dependent variation of the weld pool size. Example simulation results and comparisons with laboratory weld observations demonstrate microstructural variation with weld speed, pool shape, and pulsed-power.« less

A Monte Carlo model for 3D grain evolution during welding

DOE PAGES

Rodgers, Theron M.; Mitchell, John A.; Tikare, Veena

2017-08-04

Welding is one of the most wide-spread processes used in metal joining. However, there are currently no open-source software implementations for the simulation of microstructural evolution during a weld pass. Here we describe a Potts Monte Carlo based model implemented in the SPPARKS kinetic Monte Carlo computational framework. The model simulates melting, solidification and solid-state microstructural evolution of material in the fusion and heat-affected zones of a weld. The model does not simulate thermal behavior, but rather utilizes user input parameters to specify weld pool and heat-affect zone properties. Weld pool shapes are specified by Bezier curves, which allow formore » the specification of a wide range of pool shapes. Pool shapes can range from narrow and deep to wide and shallow representing different fluid flow conditions within the pool. Surrounding temperature gradients are calculated with the aide of a closest point projection algorithm. Furthermore, the model also allows simulation of pulsed power welding through time-dependent variation of the weld pool size. Example simulation results and comparisons with laboratory weld observations demonstrate microstructural variation with weld speed, pool shape, and pulsed-power.« less

Shape, size, and distribution of magnetic particles in Bjurbole chondrules

NASA Technical Reports Server (NTRS)

Nava, David F.

1994-01-01

Chondrules from the Bjurbole chondritic meteorite (L4) exhibit saturation remanence magnetization (SIRM) values which vary over three orders of magnitude. REM values (Natural Remanence Magnetization/SIRM) for Allende (C3V) and Chainpur (LL3) are less than 0.01 but in Bjurbole some chondrules were found to have REM values greater than 0.1 with several greater than 0.2. REM values greater than 0.1 are abnormal and cannot be acquired during weak field cooling. If exposure to a strong field (whatever the source) during the chondrules' history is responsible for the high REM values, was such history associated with a different processing which might have resulted in different shape, size, and distribution of metal particles compared to chondrules having REM values of less than 0.01? Furthermore, magnetic hysteresis results show a broad range of magnetic hardness and other intrinsic magnetic properties. These features must be related to (1) size and amount of metal; and (2) properties of, and amount of, tetrataenite in the chondrules (all chondrules thus far subjected to thermomagnetic analysis show the presence of tetrataenite). A scanning electron microscopy (SEM) study is underway to determine the relationship between the shape, size, and distribution of metal particles within individual chondrules and the magnetic properties of these chondrules. Results from the SEM study in conjunction with magnetic property data may also help to discern effects from possible lightning strikes in the nebula prior to incorporation of the chondrules into the parent body.

Shape-morphing composites with designed micro-architectures

DOE PAGES

Rodriguez, Jennifer N.; Zhu, Cheng; Duoss, Eric B.; ...

2016-06-15

Shape memory polymers (SMPs) are attractive materials due to their unique mechanical properties, including high deformation capacity and shape recovery. SMPs are easier to process, lightweight, and inexpensive compared to their metallic counterparts, shape memory alloys. However, SMPs are limited to relatively small form factors due to their low recovery stresses. Lightweight, micro-architected composite SMPs may overcome these size limitations and offer the ability to combine functional properties (e.g., electrical conductivity) with shape memory behavior. Fabrication of 3D SMP thermoset structures via traditional manufacturing methods is challenging, especially for designs that are composed of multiple materials within porous microarchitectures designedmore » for specific shape change strategies, e.g. sequential shape recovery. We report thermoset SMP composite inks containing some materials from renewable resources that can be 3D printed into complex, multi-material architectures that exhibit programmable shape changes with temperature and time. Through addition of fiber-based fillers, we demonstrate printing of electrically conductive SMPs where multiple shape states may induce functional changes in a device and that shape changes can be actuated via heating of printed composites. As a result, the ability of SMPs to recover their original shapes will be advantageous for a broad range of applications, including medical, aerospace, and robotic devices.« less

An assessment of calcite crystal growth mechanisms based on crystal size distributions

USGS Publications Warehouse

Kile, D.E.; Eberl, D.D.; Hoch, A.R.; Reddy, M.M.

2000-01-01

Calcite crystal growth experiments were undertaken to test a recently proposed model that relates crystal growth mechanisms to the shapes of crystal size distributions (CSDs). According to this approach, CSDs for minerals have three basic shapes: (1) asymptotic, which is related to a crystal growth mechanism having constant-rate nucleation accompanied by surface-controlled growth; (2) lognormal, which results from decaying-rate nucleation accompanied by surface-controlled growth; and (3) a theoretical, universal, steady-state curve attributed to Ostwald ripening. In addition, there is a fourth crystal growth mechanism that does not have a specific CSD shape, but which preserves the relative shapes of previously formed CSDs. This mechanism is attributed to supply-controlled growth. All three shapes were produced experimentally in the calcite growth experiments by modifying nucleation conditions and solution concentrations. The asymptotic CSD formed when additional reactants were added stepwise to the surface of solutions that were supersaturated with respect to calcite (initial Ω = 20, where Ω = 1 represents saturation), thereby leading to the continuous nucleation and growth of calcite crystals. Lognormal CSDs resulted when reactants were added continuously below the solution surface, via a submerged tube, to similarly supersaturated solutions (initial Ω = 22 to 41), thereby leading to a single nucleation event followed by surface-controlled growth. The Ostwald CSD resulted when concentrated reactants were rapidly mixed, leading initially to high levels of supersaturation (Ω >100), and to the formation and subsequent dissolution of very small nuclei, thereby yielding CSDs having small crystal size variances. The three CSD shapes likely were produced early in the crystallization process, in the nanometer crystal size range, and preserved during subsequent growth. Preservation of the relative shapes of the CSDs indicates that a supply-controlled growth mechanism was established and maintained during the constant-composition experiments. CSDs having shapes intermediate between lognormal and Ostwald also were generated by varying the initial levels of supersaturation (initial Ω = 28.2 to 69.2) in rapidly mixed solutions. Lognormal CSDs were observed for natural calcite crystals that are found in septarian concretions occurring in southeastern Colorado. Based on the model described above, these CSDs indicate initial growth by surface control, followed by supply-controlled growth. Thus, CSDs may be used to deduce crystal growth mechanisms from which geologic conditions early in the growth history of a mineral can be inferred. Conversely, CSD shape can be predicted during industrial crystallization by applying the appropriate conditions for a particular growth mechanism.

Nutrition shapes life-history evolution across species

PubMed Central

Swanson, Eli M.; Espeset, Anne; Mikati, Ihab; Bolduc, Isaac; Kulhanek, Robert; White, William A.; Kenzie, Susan

2016-01-01

Nutrition is a key component of life-history theory, yet we know little about how diet quality shapes life-history evolution across species. Here, we test whether quantitative measures of nutrition are linked to life-history evolution across 96 species of butterflies representing over 50 independent diet shifts. We find that butterflies feeding on high nitrogen host plants as larvae are more fecund, but their eggs are smaller relative to their body size. Nitrogen and sodium content of host plants are also both positively related to eye size. Some of these relationships show pronounced lineage-specific effects. Testis size is not related to nutrition. Additionally, the evolutionary timing of diet shifts is not important, suggesting that nutrition affects life histories regardless of the length of time a species has been adapting to its diet. Our results suggest that, at least for some lineages, species with higher nutrient diets can invest in a range of fitness-related traits like fecundity and eye size while allocating less to each egg as offspring have access to a richer diet. These results have important implications for the evolution of life histories in the face of anthropogenic changes in nutrient availability. PMID:27412282

Search for global-minimum geometries of medium-sized germanium clusters. II. Motif-based low-lying clusters Ge21-Ge29

NASA Astrophysics Data System (ADS)

Yoo, S.; Zeng, X. C.

2006-05-01

We performed a constrained search for the geometries of low-lying neutral germanium clusters GeN in the size range of 21⩽N⩽29. The basin-hopping global optimization method is employed for the search. The potential-energy surface is computed based on the plane-wave pseudopotential density functional theory. A new series of low-lying clusters is found on the basis of several generic structural motifs identified previously for silicon clusters [S. Yoo and X. C. Zeng, J. Chem. Phys. 124, 054304 (2006)] as well as for smaller-sized germanium clusters [S. Bulusu et al., J. Chem. Phys. 122, 164305 (2005)]. Among the generic motifs examined, we found that two motifs stand out in producing most low-lying clusters, namely, the six/nine motif, a puckered-hexagonal-ring Ge6 unit attached to a tricapped trigonal prism Ge9, and the six/ten motif, a puckered-hexagonal-ring Ge6 unit attached to a bicapped antiprism Ge10. The low-lying clusters obtained are all prolate in shape and their energies are appreciably lower than the near-spherical low-energy clusters. This result is consistent with the ion-mobility measurement in that medium-sized germanium clusters detected are all prolate in shape until the size N ˜65.

On the work function and the charging of small ( r ≤ 5 nm) nanoparticles in plasmas

NASA Astrophysics Data System (ADS)

Kalered, E.; Brenning, N.; Pilch, I.; Caillault, L.; Minéa, T.; Ojamäe, L.

2017-01-01

The growth of nanoparticles (NPs) in plasmas is an attractive technique where improved theoretical understanding is needed for quantitative modeling. The variation of the work function W with size for small NPs, rN P≤ 5 nm, is a key quantity for modeling of three NP charging processes that become increasingly important at a smaller size: electron field emission, thermionic electron emission, and electron impact detachment. Here we report the theoretical values of the work function in this size range. Density functional theory is used to calculate the work functions for a set of NP charge numbers, sizes, and shapes, using copper for a case study. An analytical approximation is shown to give quite accurate work functions provided that rN P > 0.4 nm, i.e., consisting of about >20 atoms, and provided also that the NPs have relaxed close to spherical shape. For smaller sizes, W deviates from the approximation, and also depends on the charge number. Some consequences of these results for nanoparticle charging are outlined. In particular, a decrease in W for NP radius below about 1 nm has fundamental consequences for their charge in a plasma environment, and thereby on the important processes of NP nucleation, early growth, and agglomeration.

Analyses of scattering characteristics of chosen anthropogenic aerosols

NASA Astrophysics Data System (ADS)

Kaszczuk, Miroslawa; Mierczyk, Zygmunt; Muzal, Michal

2008-10-01

In the work, analyses of scattering profile of chosen anthropogenic aerosols for two wavelengths (λ1 = 1064 nm and λ2 = 532 nm) were made. As an example of anthropogenic aerosol three different pyrotechnic mixtures (DM11, M2, M16) were taken. Main parameters of smoke particles were firstly analyzed and well described, taking particle shape and size into special consideration. Shape of particles was analyzed on the basis of SEM pictures, and particle size was measured. Participation of particles in each fixed fraction characterized by range of sizes was analyzed and parameters of smoke particles of characteristic sizes and function describing aerosol size distribution (ASD) were determinated. Analyses of scattering profiles were carried out on the basis of both model of scattering on spherical and nonspherical particles. In the case of spherical particles Rayleigh-Mie model was used and for nonspherical particles analyses firstly model of spheroids was used, and then Rayleigh-Mie one. For each characteristic particle one calculated value of four parameters (effective scattering cross section σSCA, effective backscattering cross section σBSCA, scattering efficiency QSCA, backscattering efficiency QBSCA) and value of backscattering coefficient β for whole particles population. Obtained results were compared with the same parameters calculated for natural aerosol (cirrus cloud).

Rime-, mixed- and glaze-ice evaluations of three scaling laws

NASA Technical Reports Server (NTRS)

Anderson, David N.

1994-01-01

This report presents the results of tests at NASA Lewis to evaluate three icing scaling relationships or 'laws' for an unheated model. The laws were LWC x time = constant, one proposed by a Swedish-Russian group and one used at ONERA in France. Icing tests were performed in the NASA Lewis Icing Research Tunnel (IRT) with cylinders ranging from 2.5- to 15.2-cm diameter. Reference conditions were chosen to provide rime, mixed and glaze ice. Scaled conditions were tested for several scenarios of size and velocity scaling, and the resulting ice shapes compared. For rime-ice conditions, all three of the scaling laws provided scaled ice shapes which closely matched reference ice shapes. For mixed ice and for glaze ice none of the scaling laws produced consistently good simulation of the reference ice shapes. Explanations for the observed results are proposed, and scaling issues requiring further study are identified.

A Facile Methodology for Engineering the Morphology of CsPbX3 Perovskite Nanocrystals under Ambient Condition

NASA Astrophysics Data System (ADS)

Seth, Sudipta; Samanta, Anunay

2016-11-01

A facile and highly reproducible room temperature, open atmosphere synthesis of cesium lead halide perovskite nanocrystals of six different morphologies is reported just by varying the solvent, ligand and reaction time. Sequential evolution of the quantum dots, nanoplates and nanobars in one medium and nanocubes, nanorods and nanowires in another medium is demonstrated. These perovskite nanoparticles are shown to be of excellent crystalline quality with high fluorescence quantum yield. A mechanism of the formation of nanoparticles of different shapes and sizes is proposed. Considering the key role of morphology in nanotechnology, this simple method of fabrication of a wide range of high quality nanocrystals of different shapes and sizes of all-inorganic lead halide perovskites, whose potential is already demonstrated in light emitting and photovoltaic applications, is likely to help widening the scope and utility of these materials in optoelectronic devices.

Estimation of the superhigh-frequency magnetic permeability of alsifer from the measured permeability of composites

NASA Astrophysics Data System (ADS)

Starostenko, S. N.; Rozanov, K. N.; Shiryaev, A. O.; Lagar'kov, A. N.; Shalygin, A. N.

2017-11-01

The magnetic permeability of alsifer was restored from the frequency dependences of the dielectric and magnetic permeabilities of powder alsifer (AlSiFe alloy)-wax matrix composites. The permeabilities were measured using the coaxial line technique within a frequency range of 0.05-20 GHz. The effect of the concentration, shape, and size of powder particles on the microwave magnetic properties of composites was considered. A good agreement between the measurement results and the Maxwell-Garnett formula generalized with consideration for the particle shape, the percolation threshold, and the skin-effect was obtained. The found sizes of particles agreed with electron microscopy and granulometry data. Both the frequency and the ferromagnetic resonance line figure of merit (FOM) for lamellar particles proved to be higher than for spherical ones. Alsifer powders were shown to be promising fillers for radioabsorbing materials.

The stabilized, wavelet-Mellin transform for analyzing the size and shape information of vocalized sounds

NASA Astrophysics Data System (ADS)

Irino, Toshio; Patterson, Roy

2005-04-01

We hear vowels produced by men, women, and children as approximately the same although there is considerable variability in glottal pulse rate and vocal tract length. At the same time, we can identify the speaker group. Recent experiments show that it is possible to identify vowels even when the glottal pulse rate and vocal tract length are condensed or expanded beyond the range of natural vocalization. This suggests that the auditory system has an automatic process to segregate information about shape and size of the vocal tract. Recently we proposed that the auditory system uses some form of Stabilized, Wavelet-Mellin Transform (SWMT) to analyze scale information in bio-acoustic sounds as a general framework for auditory processing from cochlea to cortex. This talk explains the theoretical background of the model and how the vocal information is normalized in the representation. [Work supported by GASR(B)(2) No. 15300061, JSPS.

Forging of metallic nano-objects for the fabrication of submicron-size components

NASA Astrophysics Data System (ADS)

Rösler, J.; Mukherji, D.; Schock, K.; Kleindiek, S.

2007-03-01

In recent years, nanoscale fabrication has developed considerably, but the fabrication of free-standing nanosize components is still a great challenge. The fabrication of metallic nanocomponents utilizing three basic steps is demonstrated here. First, metallic alloys are used as factories to produce a metallic raw stock of nano-objects/nanoparticles in large numbers. These objects are then isolated from the powder containing thousands of such objects inside a scanning electron microscope using manipulators, and placed on a micro-anvil or a die. Finally, the shape of the individual nano-object is changed by nanoforging using a microhammer. In this way free-standing, high-strength, metallic nano-objects may be shaped into components with dimensions in the 100 nm range. By assembling such nanocomponents, high-performance microsystems can be fabricated, which are truly in the micrometre scale (the size ratio of a system to its component is typically 10:1).

SEM fractography studies of porous vitreous carbon: a candidate biomaterial.

PubMed

Tarr, R R

1979-09-01

A new porous vitreous carbon material under development for use in orthopedic applications was investigated. Specimens were machined to appropriate sizes and fractured in one of the following modes: compression, cantilevered bending, or axial torsion. Scanning electron microscopy (SEM) was used to examine surface and internal features. Characteristics of a brittle, glassy material were noted. Findings included internal voids which appeared as craters, patches of whiskerlike fibrils, and edge impurities. Numerous microcracks caused by mechanical shaping and handling were the most remarkable structural defects. Pore channels which would allow bony ingrowth ranged in size from 50--500 micrometers with the majority between 200 and 300 micrometers. This study of porous vitreous carbon points to the need for stricter quality control in manufacturing, alternative methods for shaping and handling, and careful consideration in design and usage of a brittle material with marginal limits of safety for biomedical applications.

Malignant mast cell tumor of the thymus in an Royal College of Surgeons (RCS) rat.

PubMed

Terayama, Yui; Matsuura, Tetsuro; Ozaki, Kiyokazu

2017-01-01

A 152-week-old male Royal College of Surgeons (RCS) rat kept as a non-treated animal in a long-term animal study presented with a soft mass in the anterior mediastinum, which adhered to the pleura of the lung. Histopathologically, the mass mainly consisted of round to short spindle-shaped tumor cells that had infiltrated through the hyperplastic thymic tissue. The tumor cells were arranged in loose to dense sheets. Nuclei were moderate in size and round to spindle-shaped, with small nucleoli. Almost all tumor cells exhibited abundant eosinophilic cytoplasm, including eosinophilic granules of a range of sizes. The granules of tumor cells exhibited metachromasia with toluidine blue stain and were positive for c-kit and mast cell protease II. These findings indicate that the tumor described here represents a rare case of spontaneous malignant mast cell tumor with thymic epithelial hyperplasia.

Body size and allometric variation in facial shape in children.

PubMed

Larson, Jacinda R; Manyama, Mange F; Cole, Joanne B; Gonzalez, Paula N; Percival, Christopher J; Liberton, Denise K; Ferrara, Tracey M; Riccardi, Sheri L; Kimwaga, Emmanuel A; Mathayo, Joshua; Spitzmacher, Jared A; Rolian, Campbell; Jamniczky, Heather A; Weinberg, Seth M; Roseman, Charles C; Klein, Ophir; Lukowiak, Ken; Spritz, Richard A; Hallgrimsson, Benedikt

2018-02-01

Morphological integration, or the tendency for covariation, is commonly seen in complex traits such as the human face. The effects of growth on shape, or allometry, represent a ubiquitous but poorly understood axis of integration. We address the question of to what extent age and measures of size converge on a single pattern of allometry for human facial shape. Our study is based on two large cross-sectional cohorts of children, one from Tanzania and the other from the United States (N = 7,173). We employ 3D facial imaging and geometric morphometrics to relate facial shape to age and anthropometric measures. The two populations differ significantly in facial shape, but the magnitude of this difference is small relative to the variation within each group. Allometric variation for facial shape is similar in both populations, representing a small but significant proportion of total variation in facial shape. Different measures of size are associated with overlapping but statistically distinct aspects of shape variation. Only half of the size-related variation in facial shape can be explained by the first principal component of four size measures and age while the remainder associates distinctly with individual measures. Allometric variation in the human face is complex and should not be regarded as a singular effect. This finding has important implications for how size is treated in studies of human facial shape and for the developmental basis for allometric variation more generally. © 2017 Wiley Periodicals, Inc.

Does the foveal shape influence the image formation in human eyes?

NASA Astrophysics Data System (ADS)

Frey, Katharina; Zimmerling, Beatrice; Scheibe, Patrick; Rauscher, Franziska G.; Reichenbach, Andreas; Francke, Mike; Brunner, Robert

2017-10-01

In human eyes, the maximum visual acuity correlates locally with the fovea, a shallow depression in the retina. Previous examinations have been reduced to simple geometrical fovea models derived from postmortem preparations and considering only a few superficial ray propagation aspects. In the current study, an extended and realistic analysis of ray-optical simulations for a comprehensive anatomical realistic eye model for the anterior part and realistic aspherical human foveal topographical profiles deduced from in vivo optical coherence tomography (OCT) are presented, and the refractive index step at the transition from vitreous to retinal tissue is taken into account. The optical effect of a commonly shaped (averaged) and an extraordinarily shaped foveal pit were both compared to the analysis of an assumed pure spherical boundary layer. The influence of the aperture size, wavelength, and incident angle on the spot size and shape, as well as the axial focal and lateral centroid position is investigated, and a lateral displacement of about 2 μm and an axial shift of the best focal position of less than 4 μm are found. These findings indicate only small optical effects that are laterally in the range of inter-receptor distances and axially less than the photoreceptor outer segment dimension.

A scattering model for forested area

NASA Technical Reports Server (NTRS)

Karam, M. A.; Fung, A. K.

1988-01-01

A forested area is modeled as a volume of randomly oriented and distributed disc-shaped, or needle-shaped leaves shading a distribution of branches modeled as randomly oriented finite-length, dielectric cylinders above an irregular soil surface. Since the radii of branches have a wide range of sizes, the model only requires the length of a branch to be large compared with its radius which may be any size relative to the incident wavelength. In addition, the model also assumes the thickness of a disc-shaped leaf or the radius of a needle-shaped leaf is much smaller than the electromagnetic wavelength. The scattering phase matrices for disc, needle, and cylinder are developed in terms of the scattering amplitudes of the corresponding fields which are computed by the forward scattering theorem. These quantities along with the Kirchoff scattering model for a randomly rough surface are used in the standard radiative transfer formulation to compute the backscattering coefficient. Numerical illustrations for the backscattering coefficient are given as a function of the shading factor, incidence angle, leaf orientation distribution, branch orientation distribution, and the number density of leaves. Also illustrated are the properties of the extinction coefficient as a function of leaf and branch orientation distributions. Comparisons are made with measured backscattering coefficients from forested areas reported in the literature.

Severe impingement of lumbar disc replacements increases the functional biological activity of polyethylene wear debris.

PubMed

Baxter, Ryan M; Macdonald, Daniel W; Kurtz, Steven M; Steinbeck, Marla J

2013-06-05

Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume of particles in all three size ranges. In both cohorts, the functional biological activity correlated with the chronic inflammatory response, and the extent of rim penetration positively correlated with increasing particle size, number, and functional biological activity. The results of this study suggest that severe rim impingement increases the production of biologically relevant particles from motion-preserving lumbar total disc replacement components. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Severe Impingement of Lumbar Disc Replacements Increases the Functional Biological Activity of Polyethylene Wear Debris

PubMed Central

Baxter, Ryan M.; MacDonald, Daniel W.; Kurtz, Steven M.; Steinbeck, Marla J.

2013-01-01

Background: Wear, oxidation, and particularly rim impingement damage of ultra-high molecular weight polyethylene total disc replacement components have been observed following surgical revision. However, neither in vitro testing nor retrieval-based evidence has shown the effect(s) of impingement on the characteristics of polyethylene wear debris. Thus, we sought to determine (1) differences in polyethylene particle size, shape, number, or biological activity that correspond to mild or severe rim impingement and (2) in an analysis of all total disc replacements, regardless of impingement classification, whether there are correlations between the extent of regional damage and the characteristics of polyethylene wear debris. Methods: The extent of dome and rim damage was characterized for eleven retrieved polyethylene cores obtained at revision surgery after an average duration of implantation of 9.7 years (range, 4.6 to 16.1 years). Polyethylene wear debris was isolated from periprosthetic tissues with use of nitric acid and was imaged with use of environmental scanning electron microscopy. Subsequently, particle size, shape, number, biological activity, and chronic inflammation scores were determined. Results: Grouping of particles by size ranges that represented high biological relevance (<0.1 to 1-μm particles), intermediate biological relevance (1 to 10-μm particles), and low biological relevance (>10-μm particles) revealed an increased volume fraction of particles in the <0.1 to 1-μm and 1 to 10-μm size ranges in the mild-impingement cohort as compared with the severe-impingement cohort. The increased volume fractions resulted in a higher specific biological activity per unit particle volume in the mild-impingement cohort than in the severe-impingement cohort. However, functional biological activity, which is normalized by particle volume (mm3/g of tissue), was significantly higher in the severe-impingement cohort. This increase was due to a larger volume of particles in all three size ranges. In both cohorts, the functional biological activity correlated with the chronic inflammatory response, and the extent of rim penetration positively correlated with increasing particle size, number, and functional biological activity. Conclusions: The results of this study suggest that severe rim impingement increases the production of biologically relevant particles from motion-preserving lumbar total disc replacement components. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence. PMID:23780545

Body shape convergence driven by small size optimum in marine angelfishes.

PubMed

Frédérich, Bruno; Santini, Francesco; Konow, Nicolai; Schnitzler, Joseph; Lecchini, David; Alfaro, Michael E

2017-06-01

Convergent evolution of small body size occurs across many vertebrate clades and may reflect an evolutionary response to shared selective pressures. However it remains unclear if other aspects of phenotype undergo convergent evolution in miniaturized lineages. Here we present a comparative analysis of body size and shape evolution in marine angelfishes (Pomacanthidae), a reef fish family characterized by repeated transitions to small body size. We ask if lineages that evolve small sizes show convergent evolution in body shape. Our results reveal that angelfish lineages evolved three different stable size optima with one corresponding to the group of pygmy angelfishes ( Centropyge ). Then, we test if the observed shifts in body size are associated with changes to new adaptive peaks in shape. Our data suggest that independent evolution to small size optima have induced repeated convergence upon deeper body and steeper head profile in Centropyge These traits may favour manoeuvrability and visual awareness in these cryptic species living among corals, illustrating that functional demands on small size may be related to habitat specialization and predator avoidance. The absence of shape convergence in large marine angelfishes also suggests that more severe requirements exist for small than for large size optima. © 2017 The Author(s).

Sample size and the detection of a hump-shaped relationship between biomass and species richness in Mediterranean wetlands

USGS Publications Warehouse

Espinar, J.L.

2006-01-01

Questions: What is the observed relationship between biomass and species richness across both spatial and temporal scales in communities of submerged annual macrophytes? Does the number of plots sampled affect detection of hump-shaped pattern? Location: Don??ana National Park, southwestern Spain. Methods: A total of 102 plots were sampled during four hydrological cycles. In each hydrological cycle, the plots were distributed randomly along an environmental flooding gradient in three contrasted microhabitats located in the transition zone just below the upper marsh. In each plot (0.5 m x 0.5 m), plant density and above- and below-ground biomass of submerged vegetation were measured. The hump-shaped model was tested by using a generalized linear model (GLM). A bootstrap procedure was used to test the effect of the number of plots on the ability to detect hump-shaped patterns. Result: The area exhibited low species density with a range of 1 - 9 species and low values of biomass with a range of 0.2 - 87.6 g-DW / 0.25 m2. When data from all years and all microhabitats were combined, the relationships between biomass and species richness showed a hump-shaped pattern. The number of plots was large enough to allow detection of the hump-shaped pattern across microhabitats but it was too small to confirm the hump-shaped pattern within each individual microhabitat. Conclusion: This study provides evidence of hump-shaped patterns across microhabitats when GLM analysis is used. In communities of submerged annual macrophytes in Mediterranean wetlands, the highest species density occurs in intermediate values of biomass. The bootstrap procedure indicates that the number of plots affects the detection of hump-shaped patterns. ?? IAVS; Opulus Press.

Grain shape of basaltic ash populations: implications for fragmentation

NASA Astrophysics Data System (ADS)

Schmith, Johanne; Höskuldsson, Ármann; Holm, Paul Martin

2017-02-01

Here, we introduce a new quantitative method to produce grain shape data of bulk samples of volcanic ash, and we correlate the bulk average grain shape with magma fragmentation mechanisms. The method is based on automatic shape analysis of 2D projection ash grains in the size range 125-63 μm. Loose bulk samples from the deposits of six different basaltic eruptions were analyzed, and 20,000 shape measurements for each were obtained within 45 min using the Particle Insight™ dynamic shape analyzer (PIdsa). We used principal component analysis on a reference grain dataset to show that circularity, rectangularity, form factor, and elongation best discriminate between the grain shapes when combined. The grain population data show that the studied eruptive environments produce nearly the same range of grain shapes, although to different extents. Our new shape index (the regularity index (RI)) places an eruption on a spectrum between phreatomagmatic and dry magmatic fragmentation. Almost vesicle-free Surtseyan ash has an RI of 0.207 ± 0.002 (2σ), whereas vesiculated Hawaiian ash has an RI of 0.134 ± 0.001 (2σ). These two samples define the end-member RI, while two subglacial, one lacustrine, and another submarine ash sample show intermediate RIs of 0.168 ± 0.002 (2σ), 0.175 ± 0.002 (2σ), 0.187 ± 0.002 (2σ), and 0.191 ± 0.002 (2σ), respectively. The systematic change in RI between wet and dry eruptions suggests that the RI can be used to assess the relative roles of magmatic vs. phreatomagmatic fragmentation. We infer that both magmatic and phreatomagmatic fragmentation processes played a role in the subglacial eruptions.

Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver.

PubMed

Meškinis, Šarūnas; Čiegis, Arvydas; Vasiliauskas, Andrius; Šlapikas, Kęstutis; Gudaitis, Rimantas; Yaremchuk, Iryna; Fitio, Volodymyr; Bobitski, Yaroslav; Tamulevičius, Sigitas

2016-12-01

In the present study, diamond-like carbon films with embedded Ag nanoparticles (DLC:Ag) were deposited by reactive magnetron sputtering. Structure of the films was investigated by Raman scattering spectroscopy. Atomic force microscopy was used to define thickness of DLC:Ag films as well as to study the surface morphology and size distribution of Ag nanoparticles. Optical absorbance and reflectance spectra of the films were studied in the 180-1100-nm range. Air annealing effects on structure and optical properties of the DLC:Ag were investigated. Annealing temperatures were varied in the 180-400 °C range. Changes of size and shape of the Ag nanoclusters took place due to agglomeration. It was found that air annealing of DLC:Ag films can result in graphitization following destruction of the DLC matrix. Additional activation of surface-enhanced Raman scattering (SERS) effect in DLC:Ag films can be achieved by properly selecting annealing conditions. Annealing resulted in blueshift as well as significant narrowing of the plasmonic absorbance and reflectance peaks. Moreover, quadrupole surface plasmon resonance peaks appeared. Modeling of absorption spectra of the nanoclusters depending on the shape and surrounding media has been carried out.

Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver

NASA Astrophysics Data System (ADS)

Meškinis, Šarūnas; Čiegis, Arvydas; Vasiliauskas, Andrius; Šlapikas, Kęstutis; Gudaitis, Rimantas; Yaremchuk, Iryna; Fitio, Volodymyr; Bobitski, Yaroslav; Tamulevičius, Sigitas

2016-03-01

In the present study, diamond-like carbon films with embedded Ag nanoparticles (DLC:Ag) were deposited by reactive magnetron sputtering. Structure of the films was investigated by Raman scattering spectroscopy. Atomic force microscopy was used to define thickness of DLC:Ag films as well as to study the surface morphology and size distribution of Ag nanoparticles. Optical absorbance and reflectance spectra of the films were studied in the 180-1100-nm range. Air annealing effects on structure and optical properties of the DLC:Ag were investigated. Annealing temperatures were varied in the 180-400 °C range. Changes of size and shape of the Ag nanoclusters took place due to agglomeration. It was found that air annealing of DLC:Ag films can result in graphitization following destruction of the DLC matrix. Additional activation of surface-enhanced Raman scattering (SERS) effect in DLC:Ag films can be achieved by properly selecting annealing conditions. Annealing resulted in blueshift as well as significant narrowing of the plasmonic absorbance and reflectance peaks. Moreover, quadrupole surface plasmon resonance peaks appeared. Modeling of absorption spectra of the nanoclusters depending on the shape and surrounding media has been carried out.

The decomposition of deformation: New metrics to enhance shape analysis in medical imaging.

PubMed

Varano, Valerio; Piras, Paolo; Gabriele, Stefano; Teresi, Luciano; Nardinocchi, Paola; Dryden, Ian L; Torromeo, Concetta; Puddu, Paolo E

2018-05-01

In landmarks-based Shape Analysis size is measured, in most cases, with Centroid Size. Changes in shape are decomposed in affine and non affine components. Furthermore the non affine component can be in turn decomposed in a series of local deformations (partial warps). If the extent of deformation between two shapes is small, the difference between Centroid Size and m-Volume increment is barely appreciable. In medical imaging applied to soft tissues bodies can undergo very large deformations, involving large changes in size. The cardiac example, analyzed in the present paper, shows changes in m-Volume that can reach the 60%. We show here that standard Geometric Morphometrics tools (landmarks, Thin Plate Spline, and related decomposition of the deformation) can be generalized to better describe the very large deformations of biological tissues, without losing a synthetic description. In particular, the classical decomposition of the space tangent to the shape space in affine and non affine components is enriched to include also the change in size, in order to give a complete description of the tangent space to the size-and-shape space. The proposed generalization is formulated by means of a new Riemannian metric describing the change in size as change in m-Volume rather than change in Centroid Size. This leads to a redefinition of some aspects of the Kendall's size-and-shape space without losing Kendall's original formulation. This new formulation is discussed by means of simulated examples using 2D and 3D platonic shapes as well as a real example from clinical 3D echocardiographic data. We demonstrate that our decomposition based approaches discriminate very effectively healthy subjects from patients affected by Hypertrophic Cardiomyopathy. Copyright © 2018 Elsevier B.V. All rights reserved.

Can skull form predict the shape of the temporomandibular joint? A study using geometric morphometrics on the skulls of wolves and domestic dogs.

PubMed

Curth, Stefan; Fischer, Martin S; Kupczik, Kornelius

2017-11-01

The temporomandibular joint (TMJ) conducts and restrains masticatory movements between the mammalian cranium and the mandible. Through this functional integration, TMJ morphology in wild mammals is strongly correlated with diet, resulting in a wide range of TMJ variations. However, in artificially selected and closely related domestic dogs, dietary specialisations between breeds can be ruled out as a diversifying factor although they display an enormous variation in TMJ morphology. This raises the question of the origin of this variation. Here we hypothesise that, even in the face of reduced functional demands, TMJ shape in dogs can be predicted by skull form; i.e. that the TMJ is still highly integrated in the dog skull. If true, TMJ variation in the dog would be a plain by-product of the enormous cranial variation in dogs and its genetic causes. We addressed this hypothesis using geometric morphometry on a data set of 214 dog and 60 wolf skulls. We digitized 53 three-dimensional landmarks of the skull and the TMJ on CT-based segmentations and compared (1) the variation between domestic dog and wolf TMJs (via principal component analysis) and (2) the pattern of covariation of skull size, flexion and rostrum length with TMJ shape (via regression of centroid size on shape and partial least squares analyses). We show that the TMJ in domestic dogs is significantly more diverse than in wolves: its shape covaries significantly with skull size, flexion and rostrum proportions in patterns which resemble those observed in primates. Similar patterns in canids, which are carnivorous, and primates, which are mostly frugivorous imply the existence of basic TMJ integration patterns which are independent of dietary adaptations. However, only limited amounts of TMJ variation in dogs can be explained by simple covariation with overall skull geometry. This implies that the final TMJ shape is gained partially independently of the rest of the skull. Copyright © 2017 Elsevier GmbH. All rights reserved.

Computational Modeling of Blood Flow in the TrapEase Inferior Vena Cava Filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singer, M A; Henshaw, W D; Wang, S L

To evaluate the flow hemodynamics of the TrapEase vena cava filter using three dimensional computational fluid dynamics, including simulated thrombi of multiple shapes, sizes, and trapping positions. The study was performed to identify potential areas of recirculation and stagnation and areas in which trapped thrombi may influence intrafilter thrombosis. Computer models of the TrapEase filter, thrombi (volumes ranging from 0.25mL to 2mL, 3 different shapes), and a 23mm diameter cava were constructed. The hemodynamics of steady-state flow at Reynolds number 600 was examined for the unoccluded and partially occluded filter. Axial velocity contours and wall shear stresses were computed. Flowmore » in the unoccluded TrapEase filter experienced minimal disruption, except near the superior and inferior tips where low velocity flow was observed. For spherical thrombi in the superior trapping position, stagnant and recirculating flow was observed downstream of the thrombus; the volume of stagnant flow and the peak wall shear stress increased monotonically with thrombus volume. For inferiorly trapped spherical thrombi, marked disruption to the flow was observed along the cava wall ipsilateral to the thrombus and in the interior of the filter. Spherically shaped thrombus produced a lower peak wall shear stress than conically shaped thrombus and a larger peak stress than ellipsoidal thrombus. We have designed and constructed a computer model of the flow hemodynamics of the TrapEase IVC filter with varying shapes, sizes, and positions of thrombi. The computer model offers several advantages over in vitro techniques including: improved resolution, ease of evaluating different thrombus sizes and shapes, and easy adaptation for new filter designs and flow parameters. Results from the model also support a previously reported finding from photochromic experiments that suggest the inferior trapping position of the TrapEase IVC filter leads to an intra-filter region of recirculating/stagnant flow with very low shear stress that may be thrombogenic.« less

Assessment of trophic ecomorphology in non-alligatoroid crocodylians and its adaptive and taxonomic implications.

PubMed

Iijima, Masaya

2017-08-01

Although the establishment of trophic ecomorphology in living crocodylians can contribute to estimating feeding habits of extinct large aquatic reptiles, assessment of ecomorphological traits other than the snout shape has scarcely been conducted in crocodylians. Here, I tested the validity of the proposed trophic ecomorphological traits in crocodylians by examining the correlation between those traits and the snout shape (an established trophic ecomorphology), using 10 non-alligatoroid crocodylian species with a wide range of snout shape. I then compared the ontogenetic scaling of trophic ecomorphology to discuss its adaptive and taxonomic significance. The results demonstrated that degree of heterodonty, tooth spacing, size of supratemporal fenestra (STF), ventral extension of pterygoid flange and length of lower jaw symphysis are significantly correlated with snout shape by both non-phylogenetic and phylogenetic regression analyses. Gavialis gangeticus falls outside of 95% prediction intervals for the relationships of some traits and the snout shape, suggesting that piscivorous specialization involves the deviation from the typical transformation axis of skull characters. The comparative snout shape ontogeny revealed a universal trend of snout widening through growth in the sampled crocodylians, implying the existence of a shared size-dependent biomechanical constraint in non-alligatoroid crocodylians. Growth patterns of other traits indicated that G. gangeticus shows atypical trends for degree of heterodonty, size of STF, and symphysis length, whereas the same trends are shared for tooth spacing and ventral extension of pterygoid flange among non-alligatoroid crocodylians. These suggest that some characters are ontogenetically labile in response to prey preference shifts through growth, but other characters are in keeping with the conserved biomechanics among non-alligatoroid crocodylians. Some important taxonomic characters such as the occlusal pattern are likely correlated with ontogeny and trophic ecomorphology rather than are constrained by phylogenetic relationships, and careful reassessment of such characters might be necessary for better reconstructing the morphological phylogeny of crocodylians. © 2017 Anatomical Society.

Fractal aspects of the flow and shear behaviour of free-flowable particle size fractions of pharmaceutical directly compressible excipient sorbitol.

PubMed

Hurychová, Hana; Lebedová, Václava; Šklubalová, Zdenka; Dzámová, Pavlína; Svěrák, Tomáš; Stoniš, Jan

Flowability of powder excipients is directly influenced by their size and shape although the granulometric influence of the flow and shear behaviour of particulate matter is not studied frequently. In this work, the influence of particle size on the mass flow rate through the orifice of a conical hopper, and the cohesion and flow function was studied for four free-flowable size fractions of sorbitol for direct compression in the range of 0.080-0.400 mm. The particles were granulometricaly characterized using an optical microscopy; a boundary fractal dimension of 1.066 was estimated for regular sorbitol particles. In the particle size range studied, a non-linear relationship between the mean particle size and the mass flow rate Q10 (g/s) was detected having amaximum at the 0.245mm fraction. The best flow properties of this fraction were verified with aJenike shear tester due to the highest value of flow function and the lowest value of the cohesion. The results of this work show the importance of the right choice of the excipient particle size to achieve the best flow behaviour of particulate material.Key words: flowability size fraction sorbitol for direct compaction Jenike shear tester fractal dimension.

Multi-Instrument Manager Tool for Data Acquisition and Merging of Optical and Electrical Mobility Size Distributions

NASA Astrophysics Data System (ADS)

Tritscher, Torsten; Koched, Amine; Han, Hee-Siew; Filimundi, Eric; Johnson, Tim; Elzey, Sherrie; Avenido, Aaron; Kykal, Carsten; Bischof, Oliver F.

2015-05-01

Electrical mobility classification (EC) followed by Condensation Particle Counter (CPC) detection is the technique combined in Scanning Mobility Particle Sizers(SMPS) to retrieve nanoparticle size distributions in the range from 2.5 nm to 1 μm. The detectable size range of SMPS systems can be extended by the addition of an Optical Particle Sizer(OPS) that covers larger sizes from 300 nm to 10 μm. This optical sizing method reports an optical equivalent diameter, which is often different from the electrical mobility diameter measured by the standard SMPS technique. Multi-Instrument Manager (MIMTM) software developed by TSI incorporates algorithms that facilitate merging SMPS data sets with data based on optical equivalent diameter to compile single, wide-range size distributions. Here we present MIM 2.0, the next-generation of the data merging tool that offers many advanced features for data merging and post-processing. MIM 2.0 allows direct data acquisition with OPS and NanoScan SMPS instruments to retrieve real-time particle size distributions from 10 nm to 10 μm, which we show in a case study at a fireplace. The merged data can be adjusted using one of the merging options, which automatically determines an overall aerosol effective refractive index. As a result an indirect and average characterization of aerosol optical and shape properties is possible. The merging tool allows several pre-settings, data averaging and adjustments, as well as the export of data sets and fitted graphs. MIM 2.0 also features several post-processing options for SMPS data and differences can be visualized in a multi-peak sample over a narrow size range.

An online detection system for aggregate sizes and shapes based on digital image processing

NASA Astrophysics Data System (ADS)

Yang, Jianhong; Chen, Sijia

2017-02-01

Traditional aggregate size measuring methods are time-consuming, taxing, and do not deliver online measurements. A new online detection system for determining aggregate size and shape based on a digital camera with a charge-coupled device, and subsequent digital image processing, have been developed to overcome these problems. The system captures images of aggregates while falling and flat lying. Using these data, the particle size and shape distribution can be obtained in real time. Here, we calibrate this method using standard globules. Our experiments show that the maximum particle size distribution error was only 3 wt%, while the maximum particle shape distribution error was only 2 wt% for data derived from falling aggregates, having good dispersion. In contrast, the data for flat-lying aggregates had a maximum particle size distribution error of 12 wt%, and a maximum particle shape distribution error of 10 wt%; their accuracy was clearly lower than for falling aggregates. However, they performed well for single-graded aggregates, and did not require a dispersion device. Our system is low-cost and easy to install. It can successfully achieve online detection of aggregate size and shape with good reliability, and it has great potential for aggregate quality assurance.

Three-Dimensional Spatiotemporal Modeling of Colon Cancer Organoids Reveals that Multimodal Control of Stem Cell Self-Renewal is a Critical Determinant of Size and Shape in Early Stages of Tumor Growth.

PubMed

Yan, Huaming; Konstorum, Anna; Lowengrub, John S

2018-05-01

We develop a three-dimensional multispecies mathematical model to simulate the growth of colon cancer organoids containing stem, progenitor and terminally differentiated cells, as a model of early (prevascular) tumor growth. Stem cells (SCs) secrete short-range self-renewal promoters (e.g., Wnt) and their long-range inhibitors (e.g., Dkk) and proliferate slowly. Committed progenitor (CP) cells proliferate more rapidly and differentiate to produce post-mitotic terminally differentiated cells that release differentiation promoters, forming negative feedback loops on SC and CP self-renewal. We demonstrate that SCs play a central role in normal and cancer colon organoids. Spatial patterning of the SC self-renewal promoter gives rise to SC clusters, which mimic stem cell niches, around the organoid surface, and drive the development of invasive fingers. We also study the effects of externally applied signaling factors. Applying bone morphogenic proteins, which inhibit SC and CP self-renewal, reduces invasiveness and organoid size. Applying hepatocyte growth factor, which enhances SC self-renewal, produces larger sizes and enhances finger development at low concentrations but suppresses fingers at high concentrations. These results are consistent with recent experiments on colon organoids. Because many cancers are hierarchically organized and are subject to feedback regulation similar to that in normal tissues, our results suggest that in cancer, control of cancer stem cell self-renewal should influence the size and shape in similar ways, thereby opening the door to novel therapies.

Three-Dimensional Spatiotemporal Modeling of Colon Cancer Organoids Reveals that Multimodal Control of Stem Cell Self-Renewal is a Critical Determinant of Size and Shape in Early Stages of Tumor Growth

PubMed Central

Yan, Huaming; Konstorum, Anna

2017-01-01

We develop a three-dimensional multispecies mathematical model to simulate the growth of colon cancer organoids containing stem, progenitor and terminally differentiated cells, as a model of early (prevascular) tumor growth. Stem cells (SCs) secrete short-range self-renewal promoters (e.g., Wnt) and their long-range inhibitors (e.g., Dkk) and proliferate slowly. Committed progenitor (CP) cells proliferate more rapidly and differentiate to produce post-mitotic terminally differentiated cells that release differentiation promoters, forming negative feedback loops on SC and CP self-renewal. We demonstrate that SCs play a central role in normal and cancer colon organoids. Spatial patterning of the SC self-renewal promoter gives rise to SC clusters, which mimic stem cell niches, around the organoid surface, and drive the development of invasive fingers. We also study the effects of externally applied signaling factors. Applying bone morphogenic proteins, which inhibit SC and CP self-renewal, reduces invasiveness and organoid size. Applying hepatocyte growth factor, which enhances SC self-renewal, produces larger sizes and enhances finger development at low concentrations but suppresses fingers at high concentrations. These results are consistent with recent experiments on colon organoids. Because many cancers are hierarchically organized and are subject to feedback regulation similar to that in normal tissues, our results suggest that in cancer, control of cancer stem cell self-renewal should influence the size and shape in similar ways, thereby opening the door to novel therapies. PMID:28681151

Diffusion amid random overlapping obstacles: Similarities, invariants, approximations

PubMed Central

Novak, Igor L.; Gao, Fei; Kraikivski, Pavel; Slepchenko, Boris M.

2011-01-01

Efficient and accurate numerical techniques are used to examine similarities of effective diffusion in a void between random overlapping obstacles: essential invariance of effective diffusion coefficients (Deff) with respect to obstacle shapes and applicability of a two-parameter power law over nearly entire range of excluded volume fractions (ϕ), except for a small vicinity of a percolation threshold. It is shown that while neither of the properties is exact, deviations from them are remarkably small. This allows for quick estimation of void percolation thresholds and approximate reconstruction of Deff (ϕ) for obstacles of any given shape. In 3D, the similarities of effective diffusion yield a simple multiplication “rule” that provides a fast means of estimating Deff for a mixture of overlapping obstacles of different shapes with comparable sizes. PMID:21513372

[Evaluation of the apron as a taxonomic trait in ixodid ticks of the genus Dermacentor Koch (Ixodoidea, Ixodidae)].

PubMed

Filippova, N A; Panova, I V

1986-01-01

Study of the apron in 9 species of the genus Dermacentor from the fauna of the USSR has revealed differencies in its structure. The subgenus Dermacentor (s. str.) differs from two other subgenera both in the shape of the apron itself and in the shape of the postgenital sclerite and setae of perigenital area. Close species within each of two other subgenera differ in apron proportion, shape and size of denticles along its hind edge, and sometimes in their number. Inspite of the statistically reliable interspecific differences in apron structure a wide range of individual variability of some details and geographical specificity of samples from various places of the area were observed in species with a vast area.

Evaluation of anti-cholinesterase, antibacterial and cytotoxic activities of green synthesized silver nanoparticles using from Millettia pinnata flower extract.

PubMed

Rajakumar, Govindasamy; Gomathi, Thandapani; Thiruvengadam, Muthu; Devi Rajeswari, V; Kalpana, V N; Chung, Ill-Min

2017-02-01

The aim of this study is to develop an easy and eco-friendly method for the synthesis of Ag-NPs using extracts from the medicinal plant, Millettia pinnata flower extract and investigate the effects of Ag-NPs on acetylcholinesterase (AChE), butyrylcholinesterase (BChE), antibacterial and cytotoxicity activity. UV-Vis peak at 438 nm confirmed the Ag-NPs absorbance. The SEM analysis results confirmed the presence of spherical shaped Ag-NPs by a huge disparity in the particle size distribution with an average size of 49 ± 0.9 nm. TEM images revealed the formation of Ag-NPs with spherical shape and sizes in the range between 16 and 38 nm. The Ag-NPs showed an excellent inhibitory efficacy against AChE and BChE. The highest antibacterial activity was found against Escherichia coli (20.25 ± 0.91 mm). These nanoparticles showed the cytotoxic effects against brine shrimp (artemia saliana) nauplii with a LD 50 value of 33.92. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Two-Dimensional Liquid Structure Explains the Elevated Melting Temperatures of Gallium Nanoclusters.

PubMed

Steenbergen, Krista G; Gaston, Nicola

2016-01-13

Melting in finite-sized materials differs in two ways from the solid-liquid phase transition in bulk systems. First, there is an inherent scaling of the melting temperature below that of the bulk, known as melting point depression. Second, at small sizes changes in melting temperature become nonmonotonic and show a size-dependence that is sensitive to the structure of the particle. Melting temperatures that exceed those of the bulk material have been shown to occur for a very limited range of nanoclusters, including gallium, but have still never been ascribed a convincing physical explanation. Here, we analyze the structure of the liquid phase in gallium clusters based on molecular dynamics simulations that reproduce the greater-than-bulk melting behavior observed in experiments. We observe persistent nonspherical shape distortion indicating a stabilization of the surface, which invalidates the paradigm of melting point depression. This shape distortion suggests that the surface acts as a constraint on the liquid state that lowers its entropy relative to that of the bulk liquid and thus raises the melting temperature.

Filler features and their effects on wear and degree of conversion of particulate dental resin composites.

PubMed

Turssi, C P; Ferracane, J L; Vogel, K

2005-08-01

Based on the incomplete understanding on how filler features influence the wear resistance and monomer conversion of resin composites, this study sought to evaluate whether materials containing different shapes and combinations of size of filler particles would perform similarly in terms of three-body abrasion and degree of conversion. Twelve experimental monomodal, bimodal or trimodal composites containing either spherical or irregular shaped fillers ranging from 100 to 1500 nm were examined. Wear testings were conducted in the OHSU wear machine (n = 6) and quantified after 10(5) cycles using a profilometer. Degree of conversion (DC) was measured by FTIR spectrometry at the surface of the composites (n = 6). Data sets were analyzed using one-way Anova and Tukey's test at a significance level of 0.05. Filler size and geometry was found to have a significant effect on wear resistance and DC of composites. At specific sizes and combinations, the presence of small filler particles, either spherical or irregular, may aid in enhancing the wear resistance of composites, without compromising the percentage of reacted carbon double bonds.

Phase gradient metasurface with broadband anomalous reflection based on cross-shaped units

NASA Astrophysics Data System (ADS)

Chen, Zhaobin; Deng, Hui; Xiong, Qingxu; Liu, Chen

2018-03-01

It has been pointed out by many documents that a phase gradient metasurface with wideband characteristics can be designed by the unit with a low-quality factor ( Q value). In this paper, a cross-shaped unit with a low-quality factor Q is proposed. By changing the variable parameters of the unit, it is found that the reflection phase of the unit can achieve a stable distribution of phase gradient in the frequency range of 8.0-20.0 GHz. we analyze variation of the electromagnetic field distribution on the unit with frequency and find that the size along electrical field polarization of electromagnetic field distribution area changes with frequency. Based on our design, effective size of electromagnetic field distribution area keeps meeting the subwavelength condition, thus stable phase distribution is gained across broadened bandwidth. It is found by the analysis of the phase gradient metasurface composed of seven units that the metasurface can exhibit anomalous reflection in the wide frequency band of 8.0-20.0 GHz, and the efficiency of abnormal reflection is higher in the range of 10.0-18.0 GHz. The error between the simulation results of abnormal reflection angle and the theoretical result is only - 1.5° to 0.5° after the work of comparison. Therefore, the metasurface designed by the new cross-shaped unit has a good control on the deflection direction of the reflected wave, and shows obvious advantages in widening the bandwidth.

An experimental and numerical study of the light scattering properties of ice crystals with black carbon inclusions

NASA Astrophysics Data System (ADS)

Arienti, Marco; Geier, Manfred; Yang, Xiaoyuan; Orcutt, John; Zenker, Jake; Brooks, Sarah D.

2018-05-01

We investigate the optical properties of ice crystals nucleated on atmospheric black carbon (BC). The parameters examined in this study are the shape of the ice crystal, the volume fraction of the BC inclusion, and its location inside the crystal. We report on new spectrometer measurements of forward scattering and backward polarization from ice crystals nucleated on BC particles and grown under laboratory-controlled conditions. Data from the Cloud and Aerosol Spectrometer with Polarization (CASPOL) are used for direct comparison with single-particle calculations of the scattering phase matrix. Geometrical optics and discrete dipole approximation techniques are jointly used to provide the best compromise of flexibility and accuracy over a broad range of size parameters. Together with the interpretation of the trends revealed by the CASPOL measurements, the numerical results confirm previous reports on absorption cross-section magnification in the visible light range. Even taking into account effects of crystal shape and inclusion position, the ratio between absorption cross-section of the compound particle and the absorption cross-section of the BC inclusion alone (the absorption magnification) has a lower bound of 1.5; this value increases to 1.7 if the inclusion is centered with respect to the crystal. The simple model of BC-ice particle presented here also offers new insights on the effect of the relative position of the BC inclusion with respect to the crystal's outer surfaces, the shape of the crystal, and its size.

MRI analysis of the size and shape of the oropharynx in chronic whiplash.

PubMed

Elliott, James; Cannata, Emma; Christensen, Eric; Demaris, Joel; Kummrow, John; Manning, Erin; Nielsen, Elizabeth; Romero, Tomas; Barnes, Clifford; Jull, Gwendolen

2008-06-01

To quantify differences in the size/shape of the oropharynx between female subjects with whiplash and controls. Retrospective cohort. A total of 113 subjects (79 whiplash, 34 controls) were included. T1-weighted MRI was used to measure 1) cross-sectional area (CSA [mm(2)]) and 2) shape ratios for the oropharynx. Reliability data were established. Whiplash subjects had significantly smaller oropharynx CSAs (P < 0.001) and shape ratios (P < 0.001) compared with healthy controls. Self-reported levels of pain and disability and duration of symptoms were not associated with size and shape of the oropharynx in whiplash subjects (P = 0.75 and P = 0.99, respectively). Age and BMI did influence the size (P = 0.01) and shape of the oropharynx (P < 0.001) in the whiplash subjects, but only 20 to 30 percent of the variance could be explained by these factors. Significant difference in the size and shape of the oropharynx was noted in subjects with chronic whiplash compared with controls. Future studies are required to investigate the relationships between oropharynx morphometry and symptoms in patients with chronic whiplash.

Granulometric profiling of aeolian dust deposits by automated image analysis

NASA Astrophysics Data System (ADS)

Varga, György; Újvári, Gábor; Kovács, János; Jakab, Gergely; Kiss, Klaudia; Szalai, Zoltán

2016-04-01

Determination of granulometric parameters is of growing interest in the Earth sciences. Particle size data of sedimentary deposits provide insights into the physicochemical environment of transport, accumulation and post-depositional alterations of sedimentary particles, and are important proxies applied in paleoclimatic reconstructions. It is especially true for aeolian dust deposits with a fairly narrow grain size range as a consequence of the extremely selective nature of wind sediment transport. Therefore, various aspects of aeolian sedimentation (wind strength, distance to source(s), possible secondary source regions and modes of sedimentation and transport) can be reconstructed only from precise grain size data. As terrestrial wind-blown deposits are among the most important archives of past environmental changes, proper explanation of the proxy data is a mandatory issue. Automated imaging provides a unique technique to gather direct information on granulometric characteristics of sedimentary particles. Granulometric data obtained from automatic image analysis of Malvern Morphologi G3-ID is a rarely applied new technique for particle size and shape analyses in sedimentary geology. Size and shape data of several hundred thousand (or even million) individual particles were automatically recorded in this study from 15 loess and paleosoil samples from the captured high-resolution images. Several size (e.g. circle-equivalent diameter, major axis, length, width, area) and shape parameters (e.g. elongation, circularity, convexity) were calculated by the instrument software. At the same time, the mean light intensity after transmission through each particle is automatically collected by the system as a proxy of optical properties of the material. Intensity values are dependent on chemical composition and/or thickness of the particles. The results of the automated imaging were compared to particle size data determined by three different laser diffraction instruments (Malvern Mastersizer 3000 with a Hydro LV unit; Fritsch Analysette 22 Microtec Plus and Horiba Partica LA-950 v2) and SEM micrographs. To date, there has been very few data published on automated image analyses of size and shape parameters of sedimentary deposits, accordingly many uncertainties exist about the relationship among the results of the different applied methods. Support of the Hungarian Research Fund OTKA under contract PD108708 (for G. Varga) is gratefully acknowledged. It was additionally supported (for G. Varga) by the Bolyai János Research Scholarship of the Hungarian Academy of Sciences.

Unconstrained Recovery Characterization of Shape-Memory Polymer Networks for Cardiovascular Applications

PubMed Central

Yakacki, Christopher M.; Shandas, Robin; Lanning, Craig; Rech, Bryan; Eckstein, Alex; Gall, Ken

2009-01-01

Shape-memory materials have been proposed in biomedical device design due to their ability to facilitate minimally invasive surgery and recover to a predetermined shape in-vivo. Use of the shape-memory effect in polymers is proposed for cardiovascular stent interventions to reduce the catheter size for delivery and offer highly controlled and tailored deployment at body temperature. Shape-memory polymer networks were synthesized via photopolymerization of tert-butyl acrylate and poly (ethylene glycol) dimethacrylate to provide precise control over the thermomechanical response of the system. The free recovery response of the polymer stents at body temperature was studied as a function of glass transition temperature (Tg), crosslink density, geometrical perforation, and deformation temperature, all of which can be independently controlled. Room temperature storage of the stents was shown to be highly dependent on Tg and crosslink density. The pressurized response of the stents is also demonstrated to depend on crosslink density. This polymer system exhibits a wide range of shape-memory and thermomechanical responses to adapt and meet specific needs of minimally invasive cardiovascular devices. PMID:17296222

Sensibility of grey particle production system to energy and centrality in 60A and 200A GeV 16O-Nucleus interactions

NASA Astrophysics Data System (ADS)

Abdelsalam, A.; El–Nagdy, M. S.; Badawy, B. M.; Osman, W.; Fayed, M.

2016-06-01

The grey particle production following 60 A and 200A GeV 16O interactions with emulsion nuclei is investigated at different centralities. The evaporated target fragment multiplicity is voted as a centrality parameter. The target size effect is examined over a wide range, where the C, N and O nuclei present the light target group while the Br and Ag nuclei are the heavy group. In the framework of the nuclear limiting fragmentation hypothesis, the grey particle multiplicity characteristics depend only on the target size and centrality while the projectile size and energy are not effective. The grey particle is suggested to be a multisource production system. The emission direction in the 4π space depends upon the production source. Either the exponential decay or the Poisson’s peaking curves are the usual characteristic shapes of the grey particle multiplicity distributions. The decay shape is suggested to be a characteristic feature of the source singularity while the peaking shape is a multisource super-position. The sensibility to the centrality varies from a source to other. The distribution shape is identified at each centrality region according to the associated source contribution. In general, the multiplicity characteristics seem to be limited w.r.t. the collision system centrality using light target nuclei. The selection of the black particle multiplicity as a centrality parameter is successful through the collision with the heavy target nuclei. In the collision with the light target nuclei it may be qualitatively better to vote another centrality parameter.

The effect of cultivation on the size, shape, and persistence of disease patches in fields.

PubMed

Truscott, J E; Gilligan, C A

2001-06-19

Epidemics of soil-borne plant disease are characterized by patchiness because of restricted dispersal of inoculum. The density of inoculum within disease patches depends on a sequence comprising local amplification during the parasitic phase followed by dispersal of inoculum by cultivation during the intercrop period. The mechanisms that control size, shape, and persistence have received very little rigorous attention in epidemiological theory. Here we derive a model for dispersal of inoculum in soil by cultivation that takes account into the discrete stochastic nature of the system in time and space. Two parameters, probability of movement and mean dispersal distance, characterize lateral dispersal of inoculum by cultivation. The dispersal parameters are used in combination with the characteristic area and dimensions of host plants to identify criteria that control the shape and size of disease patches. We derive a critical value for the probability of movement for the formation of cross-shaped patches and show that this is independent of the amount of inoculum. We examine the interaction between local amplification of inoculum by parasitic activity and subsequent dilution by dispersal and identify criteria whereby asymptomatic patches may persist as inoculum falls below a threshold necessary for symptoms to appear in the subsequent crop. The model is motivated by the spread of rhizomania, an economically important soil-borne disease of sugar beet. However, the results have broad applicability to a very wide range of diseases that survive as discrete units of inoculum. The application of the model to patch dynamics of weed seeds and local introductions of genetically modified seeds is also discussed.

An instrument for the simultaneous acquisition of size, shape, and spectral fluorescence data from single aerosol particles

NASA Astrophysics Data System (ADS)

Hirst, Edwin; Kaye, Paul H.; Foot, Virginia E.; Clark, James M.; Withers, Philip B.

2004-12-01

We describe the construction of a bio-aerosol monitor designed to capture and record intrinsic fluorescence spectra from individual aerosol particles carried in a sample airflow and to simultaneously capture data relating to the spatial distribution of elastically scattered light from each particle. The spectral fluorescence data recorded by this PFAS (Particle Fluorescence and Shape) monitor contains information relating to the particle material content and specifically to possible biological fluorophores. The spatial scattering data from PFAS yields information relating to particle size and shape. The combination of these data can provide a means of aiding the discrimination of bio-aerosols from background or interferent aerosol particles which may have similar fluorescence properties but exhibit shapes and/or sizes not normally associated with biological particles. The radiation used both to excite particle fluorescence and generate the necessary spatially scattered light flux is provided by a novel compact UV fiber laser operating at 266nm wavelength. Particles drawn from the ambient environment traverse the laser beam in single file. Intrinsic particle fluorescence in the range 300-570nm is collected via an ellipsoidal concentrator into a concave grating spectrometer, the spectral data being recorded using a 16-anode linear array photomultiplier detector. Simultaneously, the spatial radiation pattern scattered by the particle over 5°-30° scattering angle and 360° of azimuth is recorded using a custom designed 31-pixel radial hybrid photodiode array. Data from up to ~5,000 particles per second may be acquired for analysis, usually performed by artificial neural network classification.

The Current Status of the Distribution Range of the Western Pine Beetle, Dendroctonus brevicomis (Curculionidae: Scolytinae) in Northern Mexico

PubMed Central

Valerio-Mendoza, O; Armendáriz-Toledano, F; Cuéllar-Rodríguez, G; Negrón, José F

2017-01-01

Abstract The distribution range of the western pine beetle Dendroctonus brevicomis LeConte (Coleoptera: Curculionidae) is supported only by scattered records in the northern parts of Mexico, suggesting that its populations may be marginal and rare in this region. In this study, we review the geographical distribution of D. brevicomis in northern Mexico and perform a geometric morphometric analysis of seminal rod shape to evaluate its reliability for identifying this species with respect to other members of the Dendroctonus frontalis Zimmermann (Coleoptera: Curculionidae) complex. Our results provide 30 new records, with 26 distributed in the Sierra Madre Occidental and 4 in the Sierra Madre Oriental. These records extend the known distribution range of D. brevicomis to Durango and Tamaulipas states in northern Mexico. Furthermore, we find high geographic variation in size and shape of the seminal rod, with conspicous differences among individuals from different geographical regions, namely west and east of the Great Basin and between mountain systems in Mexico. PMID:28922899

Fabrication and electrorotation of a novel epoxy based micromotor working in a uniform DC electric field

NASA Astrophysics Data System (ADS)

Bauer, Rita A.; Kelemen, Lóránd; Nakano, Masami; Totsuka, Atsushi; Zrínyi, Miklós

2015-10-01

We have presented the first direct observation of electric field induced rotation of epoxy based polymer rotors. Polymer disks, hollow cylinders and gears were prepared in few micrometer dimensions as rotors. Electrorotation of these sub-millimeter sized tools was studied under uniform dc electric field. The effects of shape, size and thickness were investigated. The novel epoxy based micro devices show intensive spinning in a uniform dc electric field. The rotational speed of micron-sized polymer rotors can be conveniently tuned in a wide range (between 300 and 3000 rpm) by the electric field intensity, opening new perspectives for their use in several MEMS applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaysset, Adrien; Manfrini, Mauricio; Pourtois, Geoffrey

The functionality of a cross-shaped Spin Torque Majority Gate is explored by means of micromagnetic simulations. The different input combinations are simulated varying material parameters, current density and size. The main failure mode is identified: above a critical size, a domain wall can be pinned at the center of the cross, preventing further propagation of the information. By simulating several phase diagrams, the key parameters are obtained and the operating condition is deduced. A simple relation between the domain wall width and the size of the Spin Torque Majority Gate determines the working range. Finally, a correlation is found betweenmore » the energy landscape and the main failure mode. We demonstrate that a macrospin behavior ensures a reliable majority gate operation.« less

Rare ecomorphological convergence on a complex adaptive landscape: Body size and diet mediate evolution of jaw shape in squirrels (Sciuridae).

PubMed

Zelditch, Miriam Leah; Ye, Ji; Mitchell, Jonathan S; Swiderski, Donald L

2017-03-01

Convergence is widely regarded as compelling evidence for adaptation, often being portrayed as evidence that phenotypic outcomes are predictable from ecology, overriding contingencies of history. However, repeated outcomes may be very rare unless adaptive landscapes are simple, structured by strong ecological and functional constraints. One such constraint may be a limitation on body size because performance often scales with size, allowing species to adapt to challenging functions by modifying only size. When size is constrained, species might adapt by changing shape; convergent shapes may therefore be common when size is limiting and functions are challenging. We examine the roles of size and diet as determinants of jaw shape in Sciuridae. As expected, size and diet have significant interdependent effects on jaw shape and ecomorphological convergence is rare, typically involving demanding diets and limiting sizes. More surprising is morphological without ecological convergence, which is equally common between and within dietary classes. Those cases, like rare ecomorphological convergence, may be consequences of evolving on an adaptive landscape shaped by many-to-many relationships between ecology and function, many-to-one relationships between form and performance, and one-to-many relationships between functionally versatile morphologies and ecology. On complex adaptive landscapes, ecological selection can yield different outcomes. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

The effects of relative food item size on optimal tooth cusp sharpness during brittle food item processing

PubMed Central

Berthaume, Michael A.; Dumont, Elizabeth R.; Godfrey, Laurie R.; Grosse, Ian R.

2014-01-01

Teeth are often assumed to be optimal for their function, which allows researchers to derive dietary signatures from tooth shape. Most tooth shape analyses normalize for tooth size, potentially masking the relationship between relative food item size and tooth shape. Here, we model how relative food item size may affect optimal tooth cusp radius of curvature (RoC) during the fracture of brittle food items using a parametric finite-element (FE) model of a four-cusped molar. Morphospaces were created for four different food item sizes by altering cusp RoCs to determine whether optimal tooth shape changed as food item size changed. The morphospaces were also used to investigate whether variation in efficiency metrics (i.e. stresses, energy and optimality) changed as food item size changed. We found that optimal tooth shape changed as food item size changed, but that all optimal morphologies were similar, with one dull cusp that promoted high stresses in the food item and three cusps that acted to stabilize the food item. There were also positive relationships between food item size and the coefficients of variation for stresses in food item and optimality, and negative relationships between food item size and the coefficients of variation for stresses in the enamel and strain energy absorbed by the food item. These results suggest that relative food item size may play a role in selecting for optimal tooth shape, and the magnitude of these selective forces may change depending on food item size and which efficiency metric is being selected. PMID:25320068

Impact of interaction range and curvature on crystal growth of particles confined to spherical surfaces.

PubMed

Paquay, Stefan; Both, Gert-Jan; van der Schoot, Paul

2017-07-01

When colloidal particles form a crystal phase on a spherical template, their packing is governed by the effective interaction between them and the elastic strain of bending the growing crystal. For example, if growth commences under appropriate conditions, and the isotropic crystal that forms reaches a critical size, growth continues via the incorporation of defects to alleviate elastic strain. Recently, it was experimentally found that, if defect formation is somehow not possible, the crystal instead continues growing in ribbons that protrude from the original crystal. Here we report on computer simulations in which we observe both the formation of ribbons at short interaction ranges and packings that incorporate defects if the interaction is longer-ranged. The ribbons only form above some critical crystal size, below which the nucleus is disk-shaped. We find that the scaling of the critical crystal size differs slightly from the one proposed in the literature, and we argue that this is because the actual morphology transition is caused by the competition between line tension and elastic stress, rather than the competition between chemical potential and elastic stress.

Impact of interaction range and curvature on crystal growth of particles confined to spherical surfaces

NASA Astrophysics Data System (ADS)

Paquay, Stefan; Both, Gert-Jan; van der Schoot, Paul

2017-07-01

When colloidal particles form a crystal phase on a spherical template, their packing is governed by the effective interaction between them and the elastic strain of bending the growing crystal. For example, if growth commences under appropriate conditions, and the isotropic crystal that forms reaches a critical size, growth continues via the incorporation of defects to alleviate elastic strain. Recently, it was experimentally found that, if defect formation is somehow not possible, the crystal instead continues growing in ribbons that protrude from the original crystal. Here we report on computer simulations in which we observe both the formation of ribbons at short interaction ranges and packings that incorporate defects if the interaction is longer-ranged. The ribbons only form above some critical crystal size, below which the nucleus is disk-shaped. We find that the scaling of the critical crystal size differs slightly from the one proposed in the literature, and we argue that this is because the actual morphology transition is caused by the competition between line tension and elastic stress, rather than the competition between chemical potential and elastic stress.

Oval Window Size and Shape: a Micro-CT Anatomical Study With Considerations for Stapes Surgery.

PubMed

Zdilla, Matthew J; Skrzat, Janusz; Kozerska, Magdalena; Leszczyński, Bartosz; Tarasiuk, Jacek; Wroński, Sebastian

2018-06-01

The oval window is an important structure with regard to stapes surgeries, including stapedotomy for the treatment of otosclerosis. Recent study of perioperative imaging of the oval window has revealed that oval window niche height can indicate both operative difficulty and subjective discomfort during otosclerosis surgery. With regard to shape, structures incorporated into the oval window niche, such as cartilage grafts, must be compatible with the shape of the oval window. Despite the clinical importance of the oval window, there is little information regarding its size and shape. This study assessed oval window size and shape via micro-computed tomography paired with modern morphometric methodology in the fetal, infant, child, and adult populations. Additionally, the study compared oval window size and shape between sexes and between left- and right-sided ears. No significant differences were found among traditional morphometric parameters among age groups, sides, or sexes. However, geometric morphometric methods revealed shape differences between age groups. Further, geometric morphometric methods provided the average oval window shape and most-likely shape variance. Beyond demonstrating oval window size and shape variation, the results of this report will aid in identifying patients among whom anatomical variation may contribute to surgical difficulty and surgeon discomfort, or otherwise warrant preoperative adaptations for the incorporation of materials into and around the oval window.

Bicycle helmet size, adjustment, and stability.

PubMed

Thai, Kim T; McIntosh, Andrew S; Pang, Toh Yen

2015-01-01

One of the main requirements of a protective bicycle helmet is to provide and maintain adequate coverage to the head. A poorly fitting or fastened helmet may be displaced during normal use or even ejected during a crash. The aims of the current study were to identify factors that influence the size of helmet worn, identify factors that influence helmet position and adjustment, and examine the effects of helmet size worn and adjustment on helmet stability. Recreational and commuter cyclists in Sydney were surveyed to determine how helmet size and/or adjustment affected helmet stability in the real world. Anthropometric characteristics of the head were measured and, to assess helmet stability, a test analogous to the requirements of the Australian bicycle helmet standard was undertaken. Two hundred sixty-seven cyclists were recruited across all age groups and 91% wore an AS/NZS 2063-compliant helmet. The main ethnic group was Europeans (71%) followed by Asians (18%). The circumferences of the cyclists' heads matched well the circumference of the relevant ISO headform for the chosen helmet size, but the head shapes differed with respect to ISO headforms. Age and gender were associated with wearing an incorrectly sized helmet and helmet adjustment. Older males (>55 years) were most likely to wear an incorrectly sized helmet. Adult males in the 35-54 year age group were most likely to wear a correctly adjusted helmet. Using quasistatic helmet stability tests, it was found that the correctness of adjustment, rather than size, head dimensions, or shape, significantly affected helmet stability in all test directions. Bicycle helmets worn by recreational and commuter cyclists are often the wrong size and are often worn and adjusted incorrectly, especially in children and young people. Cyclists need to be encouraged to adjust their helmets correctly. Current headforms used in standards testing may not be representative of cyclists' head shapes. This may create challenges to helmet suppliers if on one hand they optimize the helmet to meet tests on ISO-related headforms while on the other seeking to offer greater range of sizes.

Geometric morphometrics reveals sex-differential shape allometry in a spider.

PubMed

Fernández-Montraveta, Carmen; Marugán-Lobón, Jesús

2017-01-01

Common scientific wisdom assumes that spider sexual dimorphism (SD) mostly results from sexual selection operating on males. However, testing predictions from this hypothesis, particularly male size hyperallometry, has been restricted by methodological constraints. Here, using geometric morphometrics (GMM) we studied for the first time sex-differential shape allometry in a spider ( Donacosa merlini , Araneae: Lycosidae) known to exhibit the reverse pattern (i.e., male-biased) of spider sexual size dimorphism. GMM reveals previously undetected sex-differential shape allometry and sex-related shape differences that are size independent (i.e., associated to the y-intercept, and not to size scaling). Sexual shape dimorphism affects both the relative carapace-to-opisthosoma size and the carapace geometry, arguably resulting from sex differences in both reproductive roles (female egg load and male competition) and life styles (wandering males and burrowing females). Our results demonstrate that body portions may vary modularly in response to different selection pressures, giving rise to sex differences in shape, which reconciles previously considered mutually exclusive interpretations about the origins of spider SD.

The impact of cigarette pack shape, size and opening: evidence from tobacco company documents.

PubMed

Kotnowski, Kathy; Hammond, David

2013-09-01

To use tobacco industry documents on cigarette pack shape, size and openings to identify industry findings on associations with brand imagery, product attributes, consumer perceptions and behaviour. Internal tobacco industry research and marketing documents obtained through court disclosure contained in the Legacy Tobacco Documents Library were searched using keywords related to pack shapes, sizes and opening methods. The search identified 66 documents related to consumer research and marketing plans on pack shape, size and openings, drawn from 1973 to 2002. Industry research consistently found that packs that deviated from the traditional flip-top box projected impressions of 'modern', 'elegant' and 'unique' brand imagery. Alternative pack shape and openings were identified as an effective means to communicate product attributes, particularly with regard to premium quality and smooth taste. Consumer studies consistently found that pack shape, size and opening style influenced perceptions of reduced product harm, and were often used to communicate a 'lighter' product. Slim, rounded, oval and booklet packs were found to be particularly appealing among young adults, and several studies demonstrated increased purchase interest for tobacco products presented in novel packaging shape or opening. Evidence from consumer tracking reports and company presentations indicate that pack innovations in shape or opening method increased market share of brands. Consumer research by the tobacco industry between 1973 and 2002 found that variations in packaging shape, size and opening method could influence brand appeal and risk perceptions and increase cigarette sales. © 2013 Society for the Study of Addiction.

SU-F-BRCD-03: Dose Calculation of Electron Therapy Using Improved Lateral Buildup Ratio Method.

PubMed

Gebreamlak, W; Tedeschi, D; Alkhatib, H

2012-06-01

To calculate the percentage depth dose of any irregular shape electron beam using modified lateral build-up-ratio method. Percentage depth dose (PDD) curves were measured using 6, 9, 12, and 15MeV electron beam energies for applicator cone sizes of 6×6, 10×10, 14×14, and 14×14cm 2 . Circular cutouts for each cone were prepared from 2.0cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The scanning was done using a water tank and two diodes - one for the signal and the other a stationary reference outside the tank. The water surface was determined by scanning the signal diode slowly from water to air and by noting the sharp change of the percentage depth dose curve at the water/air interface. The lateral build-up-ratio (LBR) for each circular cutout was calculated from the measured PDD curve using the open field of the 14×14 cm 2 cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter (sigma) of the electron shower was calculated. Unlike the commonly accepted assumption that sigma is independent of cutout size, it is shown that the sigma value increases linearly with circular cutout size. Using this characteristic of sigma, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves. In this research, it is shown that sigma increases with cutout size. For radius of circular cutout sizes up to the equilibrium range of the electron beam, the increase of sigma with the cutout size is linear. The percentage difference of the calculated PDD from the measured PDD for irregularly shaped cutouts was under 1.0%. Similar Result was obtained for four electron beam energies (6, 9, 12, and 15MeV). © 2012 American Association of Physicists in Medicine.

Particle size analysis of sediments, soils and related particulate materials for forensic purposes using laser granulometry.

PubMed

Pye, Kenneth; Blott, Simon J

2004-08-11

Particle size is a fundamental property of any sediment, soil or dust deposit which can provide important clues to nature and provenance. For forensic work, the particle size distribution of sometimes very small samples requires precise determination using a rapid and reliable method with a high resolution. The Coulter trade mark LS230 laser granulometer offers rapid and accurate sizing of particles in the range 0.04-2000 microm for a variety of sample types, including soils, unconsolidated sediments, dusts, powders and other particulate materials. Reliable results are possible for sample weights of just 50 mg. Discrimination between samples is performed on the basis of the shape of the particle size curves and statistical measures of the size distributions. In routine forensic work laser granulometry data can rarely be used in isolation and should be considered in combination with results from other techniques to reach an overall conclusion.

Modeling Sediment Bypassing around Rocky Headlands

NASA Astrophysics Data System (ADS)

George, D. A.; Largier, J. L.; Pasternack, G. B.; Erikson, L. H.; Storlazzi, C. D.; Barnard, P.

2016-12-01

Sediment bypassing rocky headlands remains understudied despite the importance of characterizing littoral processes and sediment budgets for erosion abatement, climate change adaptation, and beach management. This study was developed to identify controlling factors on and the mechanisms supporting sediment bypassing. Sediment flux around four idealized rocky headlands was investigated using the hydrodynamic model Delft3D and spectral wave model SWAN. The experimental design involved 120 simulations to explore the influence of headland morphology, substrate composition, sediment grain size, and oceanographic forcing. Headlands represented sizes and shapes found in natural settings, grain sizes ranged from fine to medium sand, and substrates from sandy beds to offshore bedrock reefs. The oceanography included a constructed representative tide, an alongshore background current, and four wave conditions derived from observational records in the eastern Pacific Ocean. A bypassing ratio was developed for alongshore flux between upstream and downstream cross-shore transects to determine the degree of blockage by a headland. Results showed that northwesterly oblique large waves (Hs = 7 m, Tp = 16 s) generated the most flux around headlands, whereas directly incident waves blocked flux across a headland apex. The headland shape heavily influenced the sediment fate by changing the relative angle between the shoreline and the incident waves. The bypassing ratio characterized each headland's capacity to allow alongshore flux under different wave conditions. All headlands may allow flux, although larger ones block sediment more effectively, promoting their ability to be littoral cell boundaries compared to smaller headlands. The controlling factors on sediment bypassing were determined to be wave angle, shape and size of the headland, and sediment grain size. This novel numerical modeling study advances headland modeling from the generic realm to broadly applicable classes of headlands and encourages further investigation into the mechanics of sediment bypassing.

Self-associated submicron IgG1 particles for pulmonary delivery: effects of non-ionic surfactants on size, shape, stability, and aerosol performance.

PubMed

Srinivasan, Asha R; Shoyele, Sunday A

2013-03-01

The ability to produce submicron particles of monoclonal antibodies of different sizes and shapes would enhance their application to pulmonary delivery. Although non-ionic surfactants are widely used as stabilizers in protein formulations, we hypothesized that non-ionic surfactants will affect the shape and size of submicron IgG particles manufactured through precipitation. Submicron particles of IgG1 were produced by a precipitation process which explores the fact that proteins have minimum solubility but maximum precipitation at the isoelectric point. Non-ionic surfactants were used for size and shape control, and as stabilizing agents. Aerosol performance of the antibody nanoparticles was assessed using Andersen Cascade Impactor. Spinhaler® and Handihaler® were used as model DPI devices. SEM micrographs revealed that the shape of the submicron particles was altered by varying the type of surfactant added to the precipitating medium. Particle size as measured by dynamic light scattering was also varied based on the type and concentration of the surfactant. The surfactants were able to stabilize the IgG during the precipitation process. Polyhedral, sponge-like, and spherical nanoparticles demonstrated improved aerosolization properties compared to irregularly shaped (>20 μm) unprocessed particles. Stable antibody submicron particles of different shapes and sizes were prepared. Careful control of the shape of such particles is critical to ensuring optimized lung delivery by dry powder inhalation.

Acceptable Tolerances for Matching Icing Similarity Parameters in Scaling Applications

NASA Technical Reports Server (NTRS)

Anderson, David N.

2003-01-01

This paper reviews past work and presents new data to evaluate how changes in similarity parameters affect ice shapes and how closely scale values of the parameters should match reference values. Experimental ice shapes presented are from tests by various researchers in the NASA Glenn Icing Research Tunnel. The parameters reviewed are the modified inertia parameter (which determines the stagnation collection efficiency), accumulation parameter, freezing fraction, Reynolds number, and Weber number. It was demonstrated that a good match of scale and reference ice shapes could sometimes be achieved even when values of the modified inertia parameter did not match precisely. Consequently, there can be some flexibility in setting scale droplet size, which is the test condition determined from the modified inertia parameter. A recommended guideline is that the modified inertia parameter be chosen so that the scale stagnation collection efficiency is within 10 percent of the reference value. The scale accumulation parameter and freezing fraction should also be within 10 percent of their reference values. The Weber number based on droplet size and water properties appears to be a more important scaling parameter than one based on model size and air properties. Scale values of both the Reynolds and Weber numbers need to be in the range of 60 to 160 percent of the corresponding reference values. The effects of variations in other similarity parameters have yet to be established.

Effect of finite size in magnetic properties of BaFe12O19

NASA Astrophysics Data System (ADS)

Kumar, A. Sendil; Bhatnagar, Anil K.

2018-05-01

BaFe12O19 Nanoparticles are prepared through auto ignition method and structure, microstructure and magnetic properties are characterized. Samples having spherical shapes and elongated nanorods are chosen to investigate the role of finite size effect in magnetic properties. Magnetization studies show superparamagnetic, antiferromagnetic and ferrimagnetic behaviors depending on the size and shape. Very small coercive field of around 200 Oe is observed for spherical nanoparticles and a large coercive field of around 7000 Oe for nanorods is found. The shape and size plays an important role in magnetic properties of BaFe12O19 nanoparticles. Shape anisotropy has significant value compared to other anisotropies. Therefore shape of nanoparticles influences the magnetic order.

Genetic Diversity, Population Structure, and Heritability of Fruit Traits in Capsicum annuum.

PubMed

Naegele, Rachel P; Mitchell, Jenna; Hausbeck, Mary K

2016-01-01

Cultivated pepper (Capsicum annuum) is a phenotypically diverse species grown throughout the world. Wild and landrace peppers are typically small-fruited and pungent, but contain many important traits such as insect and disease resistance. Cultivated peppers vary dramatically in size, shape, pungency, and color, and often lack resistance traits. Fruit characteristics (e.g. shape and pericarp thickness) are major determinants for cultivar selection, and their association with disease susceptibility can reduce breeding efficacy. This study evaluated a diverse collection of peppers for mature fruit phenotypic traits, correlation among fruit traits and Phytophthora fruit rot resistance, genetic diversity, population structure, and trait broad sense heritability. Significant differences within all fruit phenotype categories were detected among pepper lines. Fruit from Europe had the thickest pericarp, and fruit from Ecuador had the thinnest. For fruit shape index, fruit from Africa had the highest index, while fruit from Europe had the lowest. Five genetic clusters were detected in the pepper population and were significantly associated with fruit thickness, end shape, and fruit shape index. The genetic differentiation between clusters ranged from little to very great differentiation when grouped by the predefined categories. Broad sense heritability for fruit traits ranged from 0.56 (shoulder height) to 0.98 (pericarp thickness). When correlations among fruit phenotypes and fruit disease were evaluated, fruit shape index was negatively correlated with pericarp thickness, and positively correlated with fruit perimeter. Pepper fruit pericarp, perimeter, and width had a slight positive correlation with Phytophthora fruit rot, whereas fruit shape index had a slight negative correlation.

Genetic Diversity, Population Structure, and Heritability of Fruit Traits in Capsicum annuum

PubMed Central

Naegele, Rachel P.; Mitchell, Jenna; Hausbeck, Mary K.

2016-01-01

Cultivated pepper (Capsicum annuum) is a phenotypically diverse species grown throughout the world. Wild and landrace peppers are typically small-fruited and pungent, but contain many important traits such as insect and disease resistance. Cultivated peppers vary dramatically in size, shape, pungency, and color, and often lack resistance traits. Fruit characteristics (e.g. shape and pericarp thickness) are major determinants for cultivar selection, and their association with disease susceptibility can reduce breeding efficacy. This study evaluated a diverse collection of peppers for mature fruit phenotypic traits, correlation among fruit traits and Phytophthora fruit rot resistance, genetic diversity, population structure, and trait broad sense heritability. Significant differences within all fruit phenotype categories were detected among pepper lines. Fruit from Europe had the thickest pericarp, and fruit from Ecuador had the thinnest. For fruit shape index, fruit from Africa had the highest index, while fruit from Europe had the lowest. Five genetic clusters were detected in the pepper population and were significantly associated with fruit thickness, end shape, and fruit shape index. The genetic differentiation between clusters ranged from little to very great differentiation when grouped by the predefined categories. Broad sense heritability for fruit traits ranged from 0.56 (shoulder height) to 0.98 (pericarp thickness). When correlations among fruit phenotypes and fruit disease were evaluated, fruit shape index was negatively correlated with pericarp thickness, and positively correlated with fruit perimeter. Pepper fruit pericarp, perimeter, and width had a slight positive correlation with Phytophthora fruit rot, whereas fruit shape index had a slight negative correlation. PMID:27415818

Correlation between size distribution and luminescence properties of spool-shaped InAs quantum dots

NASA Astrophysics Data System (ADS)

Xie, H.; Prioli, R.; Torelly, G.; Liu, H.; Fischer, A. M.; Jakomin, R.; Mourão, R.; Kawabata, R.; Pires, M. P.; Souza, P. L.; Ponce, F. A.

2017-05-01

InAs QDs embedded in an AlGaAs matrix have been produced by MOVPE with a partial capping and annealing technique to achieve controllable QD energy levels that could be useful for solar cell applications. The resulted spool-shaped QDs are around 5 nm in height and have a log-normal diameter distribution, which is observed by TEM to range from 5 to 15 nm. Two photoluminescence peaks associated with QD emission are attributed to the ground and the first excited states transitions. The luminescence peak width is correlated with the distribution of QD diameters through the diameter dependent QD energy levels.

A Novel Method for Proximity Detection of Moving Targets Using a Large-Scale Planar Capacitive Sensor System

PubMed Central

Ye, Yong; Deng, Jiahao; Shen, Sanmin; Hou, Zhuo; Liu, Yuting

2016-01-01

A novel method for proximity detection of moving targets (with high dielectric constants) using a large-scale (the size of each sensor is 31 cm × 19 cm) planar capacitive sensor system (PCSS) is proposed. The capacitive variation with distance is derived, and a pair of electrodes in a planar capacitive sensor unit (PCSU) with a spiral shape is found to have better performance on sensitivity distribution homogeneity and dynamic range than three other shapes (comb shape, rectangular shape, and circular shape). A driving excitation circuit with a Clapp oscillator is proposed, and a capacitance measuring circuit with sensitivity of 0.21 Vp−p/pF is designed. The results of static experiments and dynamic experiments demonstrate that the voltage curves of static experiments are similar to those of dynamic experiments; therefore, the static data can be used to simulate the dynamic curves. The dynamic range of proximity detection for three projectiles is up to 60 cm, and the results of the following static experiments show that the PCSU with four neighboring units has the highest sensitivity (the sensitivities of other units are at least 4% lower); when the attack angle decreases, the intensity of sensor signal increases. This proposed method leads to the design of a feasible moving target detector with simple structure and low cost, which can be applied in the interception system. PMID:27196905

Abundance and morphometry changes across the high-mountain lake-size gradient in the tropical Andes of Southern Ecuador

NASA Astrophysics Data System (ADS)

Mosquera, Pablo V.; Hampel, Henrietta; Vázquez, Raúl F.; Alonso, Miguel; Catalan, Jordi

2017-08-01

The number, size, and shape of lakes are key determinants of the ecological functionality of a lake district. The lake area scaling relationships with lake number and volume enable upscaling biogeochemical processes and spatially considering organisms' metapopulation dynamics. These relationships vary regionally depending on the geomorphological context, particularly in the range of lake area <1 km2 and mountainous regions. The Cajas Massif (Southern Ecuador) holds a tropical mountain lake district with 5955 water bodies. The number of lakes deviates from a power law relationship with the lake area at both ends of the size range; similarly to the distributions found in temperate mountain ranges. The deviation of each distribution tail does not respond to the same cause. The marked relief limits the size of the largest lakes at high altitudes, whereas ponds are prompt to a complete infilling. A bathymetry survey of 202 lakes, selected across the full-size range, revealed a volume-area scaling coefficient larger than those found for other lake areas of glacial origin but softer relief. Water renewal time is not consistently proportional to the lake area due to the volume-area variation in midsize lakes. The 85% of the water surface is in lakes >104 m2 and 50% of the water resources are held in a few ones (˜10) deeper than 18 m. Therefore, midlakes and large lakes are by far more biogeochemically relevant than ponds and shallow lakes in this tropical mountain lake district.

Method of making bonded or sintered permanent magnets

DOEpatents

McCallum, R.W.; Dennis, K.W.; Lograsso, B.K.; Anderson, I.E.

1993-08-31

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density.

Method of making bonded or sintered permanent magnets

DOEpatents

McCallum, R.W.; Dennis, K.W.; Lograsso, B.K.; Anderson, I.E.

1995-11-28

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density. 14 figs.

Method of making bonded or sintered permanent magnets

DOEpatents

McCallum, R. William; Dennis, Kevin W.; Lograsso, Barbara K.; Anderson, Iver E.

1995-11-28

An isotropic permanent magnet is made by mixing a thermally responsive, low viscosity binder and atomized rare earth-transition metal (e.g., iron) alloy powder having a carbon-bearing (e.g., graphite) layer thereon that facilitates wetting and bonding of the powder particles by the binder. Prior to mixing with the binder, the atomized alloy powder may be sized or classified to provide a particular particle size fraction having a grain size within a given relatively narrow range. A selected particle size fraction is mixed with the binder and the mixture is molded to a desired complex magnet shape. A molded isotropic permanent magnet is thereby formed. A sintered isotropic permanent magnet can be formed by removing the binder from the molded mixture and thereafter sintering to full density.

Metrological characterization of 3D imaging devices

NASA Astrophysics Data System (ADS)

Guidi, G.

2013-04-01

Manufacturers often express the performance of a 3D imaging device in various non-uniform ways for the lack of internationally recognized standard requirements for metrological parameters able to identify the capability of capturing a real scene. For this reason several national and international organizations in the last ten years have been developing protocols for verifying such performance. Ranging from VDI/VDE 2634, published by the Association of German Engineers and oriented to the world of mechanical 3D measurements (triangulation-based devices), to the ASTM technical committee E57, working also on laser systems based on direct range detection (TOF, Phase Shift, FM-CW, flash LADAR), this paper shows the state of the art about the characterization of active range devices, with special emphasis on measurement uncertainty, accuracy and resolution. Most of these protocols are based on special objects whose shape and size are certified with a known level of accuracy. By capturing the 3D shape of such objects with a range device, a comparison between the measured points and the theoretical shape they should represent is possible. The actual deviations can be directly analyzed or some derived parameters can be obtained (e.g. angles between planes, distances between barycenters of spheres rigidly connected, frequency domain parameters, etc.). This paper shows theoretical aspects and experimental results of some novel characterization methods applied to different categories of active 3D imaging devices based on both principles of triangulation and direct range detection.

Shape and Size of Microfine Aggregates: X-ray Microcomputed Tomgraphy vs. Laser Diffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erdogan,S.; Garboczi, E.; Fowler, D.

Microfine rock aggregates, formed naturally or in a crushing process, pass a No. 200 ASTM sieve, so have at least two orthogonal principal dimensions less than 75 {mu}m, the sieve opening size. In this paper, for the first time, we capture true 3-D shape and size data of several different types of microfine aggregates, using X-ray microcomputed tomography ({mu}CT) with a voxel size of 2 {mu}m. This information is used to generate shape analyses of various kinds. Particle size distributions are also generated from the {mu}CT data and quantitatively compared to the results of laser diffraction, which is the leadingmore » method for measuring particle size distributions of sub-millimeter size particles. By taking into account the actual particle shape, the differences between {mu}CT and laser diffraction can be qualitatively explained.« less

Contribution of the hydrostatic pressure to the shape of silver island particles

NASA Astrophysics Data System (ADS)

Anno, E.; Hoshino, R.

1984-09-01

We have investigated the shape change of silver island particles caused by the surface energy reduction. When the surface energy was reduced by the reaction with hydrogen sulfide, the flattening of the particles was observed. As is well known, the similar shape change takes place when the particle size increases. Therefore, the particle shape is considered to depend both on the surface energy and the particle size. From this consideration, we predict the contribution of the hydrostatic pressure P to the particle shape. As evidence of this contribution, we consider the existence of the critical size below which P is larger than the adhesive force FA between deposit and substrate surface. Investigating the influence of the flattening due to the surface energy reduction on the size distribution, the critical size is found and estimated to be about 80 Å in diameter. This value is comparable with that estimated from the condition P = FA.

Monodisperse Block Copolymer Particles with Controllable Size, Shape, and Nanostructure

NASA Astrophysics Data System (ADS)

Shin, Jae Man; Kim, Yongjoo; Kim, Bumjoon; PNEL Team

Shape-anisotropic particles are important class of novel colloidal building block for their functionality is more strongly governed by their shape, size and nanostructure compared to conventional spherical particles. Recently, facile strategy for producing non-spherical polymeric particles by interfacial engineering received significant attention. However, achieving uniform size distribution of particles together with controlled shape and nanostructure has not been achieved. Here, we introduce versatile system for producing monodisperse BCP particles with controlled size, shape and morphology. Polystyrene-b-polybutadiene (PS-b-PB) self-assembled to either onion-like or striped ellipsoid particle, where final structure is governed by amount of adsorbed sodium dodecyl sulfate (SDS) surfactant at the particle/surrounding interface. Further control of molecular weight and particle size enabled fine-tuning of aspect ratio of ellipsoid particle. Underlying physics of free energy for morphology formation and entropic penalty associated with bending BCP chains strongly affects particle structure and specification.

Formulation of a dry powder influenza vaccine for nasal delivery.

PubMed

Garmise, Robert J; Mar, Kevin; Crowder, Timothy M; Hwang, C Robin; Ferriter, Matthew; Huang, Juan; Mikszta, John A; Sullivan, Vincent J; Hickey, Anthony J

2006-03-10

The purpose of this research was to prepare a dry powder vaccine formulation containing whole inactivated influenza virus (WIIV) and a mucoadhesive compound suitable for nasal delivery. Powders containing WIIV and either lactose or trehalose were produced by lyophilization. A micro-ball mill was used to reduce the lyophilized cake to sizes suitable for nasal delivery. Chitosan flakes were reduced in size using a cryo-milling technique. Milled powders were sieved between 45 and 125 microm aggregate sizes and characterized for particle size and distribution, morphology, and flow properties. Powders were blended in the micro-ball mill without the ball. Lyophilization followed by milling produced irregularly shaped, polydisperse particles with a median primary particle diameter of approximately 21 microm and a yield of approximately 37% of particles in the 45 to 125 microm particle size range. Flow properties of lactose and trehalose powders after lyophilization followed by milling and sieving were similar. Cryo-milling produced a small yield of particles in the desired size range (<10%). Lyophilization followed by milling and sieving produced particles suitable for nasal delivery with different physicochemical properties as a function of processing conditions and components of the formulation. Further optimization of particle size and morphology is required for these powders to be suitable for clinical evaluation.

Viscothermal Coupling Effects on Sound Attenuation in Concentrated Colloidal Dispersions.

NASA Astrophysics Data System (ADS)

Han, Wei

1995-11-01

This thesis describes a Unified Coupled Phase Continuum (UCPC) model to analyze sound propagation through aerosols, emulsions and suspensions in terms of frequency dependent attenuation coefficient and sound speed. Expressions for the viscous and thermal coupling coefficients explicitly account for the effects of particle size, shape factor, orientation as well as concentration and the sound frequency. The UCPC model also takes into account the intrinsic acoustic absorption within the fluid medium due to its viscosity and heat conductivity. The effective complex wave number as a function of frequency is derived. A frequency- and concentration-dependent complex Nusselt number for the interfacial thermal coupling coefficient is derived using an approximate similarity between the 'viscous skin drag' and 'heat conduction flux' associated with the discontinuous suspended phase, on the basis of a cell model. The theoretical predictions of attenuation spectra provide satisfactory agreement with reported experimental data on two concentrated suspensions (polystyrene latex and kaolin pigment), two concentrated emulsions (toluene -in-water, n-hexadecane-in-water), and two aerosols (oleic acid droplets-in-nitrogen, alumina-in-air), covering a wide range of relative magnitudes (from 10^ {-3} to 10^{3}) of thermal versus viscous contributions, for dispersed phase volume fractions as high as 50%. The relative differences between the additive result of separate viscous and thermal loss estimates and combined viscothermal absorption results are also presented. Effects of particle shape on viscous attenuation of sound in concentrated suspensions of non-spherical clay particles are studied. Attenuation spectra for 18 frequencies from 3 to 100 MHz are measured and analyzed for eleven kaolin clay slurries with solid concentrations ranging from 0.6% to 35% (w/w). A modified viscous drag coefficient that considers frequency, concentration, particle size, shape and orientation of spheroids, is developed and applied to estimate the viscous attenuation coefficients. With incorporation of particle size and shape distributions (PSSD), predictions agree quantitatively with observed attenuation coefficients. The effects of particle aspect ratio and orientation become more evident as particle concentrations and frequencies are increased. The UCPC model combined with the ultrasonic spectroscopy techniques can provide for theoretical and experimental frameworks in characterization of concentrated colloidal dispersions.

Effect of shape and size of lung and chest wall on stresses in the lung

NASA Technical Reports Server (NTRS)

Vawter, D. L.; Matthews, F. L.; West, J. B.

1975-01-01

To understand better the effect of shape and size of lung and chest wall on the distribution of stresses, strains, and surface pressures, we analyzed a theoretical model using the technique of finite elements. First we investigated the effects of changing the chest wall shape during expansion, and second we studied lungs of a variety of inherent shapes and sizes. We found that, in general, the distributions of alveolar size, mechanical stresses, and surface pressures in the lungs were dominated by the weight of the lung and that changing the shape of the lung or chest wall had relatively little effect. Only at high states of expansion where the lung was very stiff did changing the shape of the chest wall cause substantial changes. Altering the inherent shape of the lung generally had little effect but the topographical differences in stresses and surface pressures were approximately proportional to lung height. The results are generally consistent with those found in the dog by Hoppin et al (1969).

Sensing human hand motions for controlling dexterous robots

NASA Technical Reports Server (NTRS)

Marcus, Beth A.; Churchill, Philip J.; Little, Arthur D.

1988-01-01

The Dexterous Hand Master (DHM) system is designed to control dexterous robot hands such as the UTAH/MIT and Stanford/JPL hands. It is the first commercially available device which makes it possible to accurately and confortably track the complex motion of the human finger joints. The DHM is adaptable to a wide variety of human hand sizes and shapes, throughout their full range of motion.

How river rocks round: resolving the shape-size paradox.

PubMed

Domokos, Gabor; Jerolmack, Douglas J; Sipos, Andras Á; Török, Akos

2014-01-01

River-bed sediments display two universal downstream trends: fining, in which particle size decreases; and rounding, where pebble shapes evolve toward ellipsoids. Rounding is known to result from transport-induced abrasion; however many researchers argue that the contribution of abrasion to downstream fining is negligible. This presents a paradox: downstream shape change indicates substantial abrasion, while size change apparently rules it out. Here we use laboratory experiments and numerical modeling to show quantitatively that pebble abrasion is a curvature-driven flow problem. As a consequence, abrasion occurs in two well-separated phases: first, pebble edges rapidly round without any change in axis dimensions until the shape becomes entirely convex; and second, axis dimensions are then slowly reduced while the particle remains convex. Explicit study of pebble shape evolution helps resolve the shape-size paradox by reconciling discrepancies between laboratory and field studies, and enhances our ability to decipher the transport history of a river rock.

How River Rocks Round: Resolving the Shape-Size Paradox

PubMed Central

Domokos, Gabor; Jerolmack, Douglas J.; Sipos, Andras Á.; Török, Ákos

2014-01-01

River-bed sediments display two universal downstream trends: fining, in which particle size decreases; and rounding, where pebble shapes evolve toward ellipsoids. Rounding is known to result from transport-induced abrasion; however many researchers argue that the contribution of abrasion to downstream fining is negligible. This presents a paradox: downstream shape change indicates substantial abrasion, while size change apparently rules it out. Here we use laboratory experiments and numerical modeling to show quantitatively that pebble abrasion is a curvature-driven flow problem. As a consequence, abrasion occurs in two well-separated phases: first, pebble edges rapidly round without any change in axis dimensions until the shape becomes entirely convex; and second, axis dimensions are then slowly reduced while the particle remains convex. Explicit study of pebble shape evolution helps resolve the shape-size paradox by reconciling discrepancies between laboratory and field studies, and enhances our ability to decipher the transport history of a river rock. PMID:24533132

A morphogram for silica-witherite biomorphs and its application to microfossil identification in the early earth rock record.

PubMed

Rouillard, J; García-Ruiz, J-M; Gong, J; van Zuilen, M A

2018-05-01

Archean hydrothermal environments formed a likely site for the origin and early evolution of life. These are also the settings, however, were complex abiologic structures can form. Low-temperature serpentinization of ultramafic crust can generate alkaline, silica-saturated fluids in which carbonate-silica crystalline aggregates with life-like morphologies can self-assemble. These "biomorphs" could have adsorbed hydrocarbons from Fischer-Tropsch type synthesis processes, leading to metamorphosed structures that resemble carbonaceous microfossils. Although this abiogenic process has been extensively cited in the literature and has generated important controversy, so far only one specific biomorph type with a filamentous shape has been discussed for the interpretation of Archean microfossils. It is therefore critical to precisely determine the full distribution in morphology and size of these biomorphs, and to study the range of plausible geochemical conditions under which these microstructures can form. Here, a set of witherite-silica biomorph synthesis experiments in silica-saturated solutions is presented, for a range of pH values (from 9 to 11.5) and barium ion concentrations (from 0.6 to 40 mmol/L BaCl 2 ). Under these varying conditions, a wide range of life-like structures is found, from fractal dendrites to complex shapes with continuous curvature. The size, spatial concentration, and morphology of the biomorphs are strongly controlled by environmental parameters, among which pH is the most important. This potentially limits the diversity of environments in which the growth of biomorphs could have occurred on Early Earth. Given the variety of the observed biomorph morphologies, our results show that the morphology of an individual microstructure is a poor criterion for biogenicity. However, biomorphs may be distinguished from actual populations of cellular microfossils by their wide, unimodal size distribution. Biomorphs grown by diffusion in silica gel can be differentiated by their continuous gradient in size, spatial density, and morphology along the direction of diffusion. © 2018 The Authors. Geobiology Published by John Wiley & Sons Ltd.

The relationship between mammal faunas and climatic instability since the Last Glacial Maximum: A Nearctic vs. Western Palearctic comparison

NASA Astrophysics Data System (ADS)

Torres-Romero, Erik Joaquín; Varela, Sara; Fisher, Jason T.; Olalla-Tárraga, Miguel Á.

2017-07-01

Climate has played a key role in shaping the geographic patterns of biodiversity. The imprint of Quaternary climatic fluctuations is particularly evident on the geographic distribution of Holarctic faunas, which dramatically shifted their ranges following the alternation of glacial-interglacial cycles during the Pleistocene. Here, we evaluate the existence of differences between climatically stable and unstable regions - defined on the basis of climatic change velocity since the Last Glacial Maximum - in the geographic distribution of several biological attributes of extant terrestrial mammals of the Nearctic and Western Palearctic regions. Specifically, we use a macroecological approach to assess the dissimilarities in species richness, range size, body size, longevity and litter size of species that inhabit regions with contrasting histories of climatic stability. While several studies have documented how the distributional ranges of animals can be affected by long-term historic climatic fluctuations, there is less evidence on the species-specific traits that determine their responsiveness under such climatic instability. We find that climatically unstable areas have more widespread species and lower mammal richness than stable regions in both continents. We detected stronger signatures of historical climatic instability on the geographic distribution of body size in the Nearctic region, possibly reflecting lagged responses to recolonize deglaciated regions. However, the way that animals respond to climatic fluctuations varies widely among species and we were unable to find a relationship between climatic instability and other mammal life-history traits (longevity and litter size) in any of the two biogeographic regions. We, therefore, conclude that beyond some biological traits typical of macroecological analyses such as geographic range size and body size, it is difficult to infer the responsiveness of species distributions to climate change solely based on particular life-history traits.

The synthesis and characterization of iron nanoparticles

NASA Astrophysics Data System (ADS)

Bennett, Tyler

Nanoparticle synthesis has garnered attention for technological applications for catalysts, industrial processing, and medical applications. The size ranges for these is in the particles nanostructural domain. Pure iron nanoparticles have been of particular interest for their reactivity and relative biological inertness. Applications include cancer treatment and carrying medicine to a relevant site. Unfortunately, because of their reactivity, pure iron nanoparticles have been difficult to study. This is because of their accelerated tendency to form oxides in air, due to the increased surface area to volume ratio. Using synthesis processes with polyphenols or long chain amines, air stable iron nanoparticles have been produced with a diameter size range of ~ 2 to about ~10 nm, but apparently have transformed due to internal pressure and crystallographic defects to the FCC phase. The FCC crystals have been seen to form icosahedral and decahedral shapes. This size is within the range for use as a catalyst for the growth of both carbon nanotubes and boron nitride nanotubes as well for biomedical applications. The advantages of these kinds of catalysts are that nanotube growth can be for the first time separated from the catalyst formation. Additionally, the catalyst size can be preselected for a certain size nanotube to grow. In summary: (1) we found the size distributions of nanoparticles for various synthesis processes, (2) we discovered the right size range for growth of nanotubes from the iron nanoparticles, (3) the nanoparticles are under a very high internal pressure, (4) the nanoparticles are in the FCC phase, (5) they appear to be in icosahedral and decahedral structures, (6) they undergo room temperature twinning, (7) the FCC crystals are distorted due to carbon in octahedral sites, (8) the iron nanoparticles are stable in air, (9) adding small amounts of copper make the iron nanoparticles smaller.

The relationship between asymmetry, size and unusual venation in honey bees (Apis mellifera).

PubMed

Łopuch, S; Tofilski, A

2016-06-01

Despite the fact that symmetry is common in nature, it is rarely perfect. Because there is a wide range of phenotypes which differs from the average one, the asymmetry should increase along with deviation. Therefore, the aim of this study was to assess the level of asymmetry in normal individuals as well as in phenodeviants categorized as minor or major based on abnormalities in forewing venation in honey bees. Shape fluctuating asymmetry (FA) was lower in normal individuals and minor phenodeviants compared with major phenodeviants, whereas the former two categories were comparable in drones. In workers and queens, there were not significant differences in FA shape between categories. FA size was significantly lower in normal individuals compared with major phenodeviant drones and higher compared with minor phenodeviant workers. In queens, there were no significant differences between categories. The correlation between FA shape and FA size was significantly positive in drones, and insignificant in workers and queens. Moreover, a considerable level of directional asymmetry was found as the right wing was constantly bigger than the left one. Surprisingly, normal individuals were significantly smaller than minor phenodeviants in queens and drones, and they were comparable with major phenodeviants in all castes. The correlation between wing size and wing asymmetry was negative, indicating that smaller individuals were more asymmetrical. The high proportion of phenodeviants in drones compared with workers and queens confirmed their large variability. Thus, the results of the present study showed that minor phenodeviants were not always intermediate as might have been expected.

Analyses on the Performance and Interaction Between the Impeller and Casing in a Small-Size Turbo-Compressor

NASA Astrophysics Data System (ADS)

Kim, Youn-Jea; Kim, Dong-Won

The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-size turbo-compressor are investigated. Numerical analysis is conducted for the turbo-compressor with circular and single volute casings from the inlet to a discharge nozzle. The optimum design for each element is important to develop the small-size turbo-compressor using alternative refrigerant as a working fluid. Typically, the rotating speed of the compressor is in the range of 40000-45000rpm because of the small size of an impeller diameter. A blade of an impeller has backswept two-dimensional shape due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside the entire impeller, the vaneless diffuser and the casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For compressible turbulent flow fields, the continuity and time-averaged three-dimensional Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained with various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. To prove the accuracy of numerical results, measurements of static pressure around the casing and pressure difference between the inlet and the outlet of the compressor are performed for the circular casing. The comparison of experimental and numerical results is conducted, and reasonable agreement is obtained.

Target recognition for ladar range image using slice image

NASA Astrophysics Data System (ADS)

Xia, Wenze; Han, Shaokun; Wang, Liang

2015-12-01

A shape descriptor and a complete shape-based recognition system using slice images as geometric feature descriptor for ladar range images are introduced. A slice image is a two-dimensional image generated by three-dimensional Hough transform and the corresponding mathematical transformation. The system consists of two processes, the model library construction and recognition. In the model library construction process, a series of range images are obtained after the model object is sampled at preset attitude angles. Then, all the range images are converted into slice images. The number of slice images is reduced by clustering analysis and finding a representation to reduce the size of the model library. In the recognition process, the slice image of the scene is compared with the slice image in the model library. The recognition results depend on the comparison. Simulated ladar range images are used to analyze the recognition and misjudgment rates, and comparison between the slice image representation method and moment invariants representation method is performed. The experimental results show that whether in conditions without noise or with ladar noise, the system has a high recognition rate and low misjudgment rate. The comparison experiment demonstrates that the slice image has better representation ability than moment invariants.

Mass and heat transfer in crushed oil shale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carley, J.F.; Ott, L.L.; Swecker, J.L.

1995-03-01

Studies of heat and mass transfer in packed beds, which disagree substantially in their findings, have nearly all been done with beds of regular particles of uniform size, whereas oil-shale retorting involves particles of diverse irregular shapes and sizes. The authors, in 349 runs, measured mass-transfer rates front naphthalene particles buried in packed beds by passing through air at room temperature. An exact catalog between convection of heat and mass makes it possible to infer heat-transfer coefficients from measured mass-transfer coefficients and fluid properties. Some beds consisted of spheres, naphthalene and inert, of the same, contrasting or distributed sizes. Inmore » some runs, naphthalene spheres were buried in beds of crushed shale, some in narrow screen ranges and others with a wide size range. In others, naphthalene lozenges of different shapes were buried in beds of crushed shale in various bed axis orientations. This technique permits calculation of the mass-transfer coefficient for each active particle in the bed rather than, as in most past studies, for the bed as a whole. The data are analyzed by the traditional correlation of Colburn j{sub D} vs. Reynolds number and by multiple regression of the mass-transfer coefficient on air rate, sizes of active and inert particles, void fraction, and temperature. Principal findings are: local Reynolds number should be based on the active-particle size, not the average for the whole bed; differences between shallow and deep beds are not appreciable; mass transfer is 26% faster for spheres and lozenges buried in shale than in all-sphere beds; orientation of lozenges in shale beds has little or no effect on mass-transfer rate; and for mass or heat transfer in shale beds, log(j{center_dot}{epsilon}) = {minus}0.0747 - 0.6344 log N{sub Re} + 0. 0592 log {sup 2} N{sub Re}.« less

Gas dispersion and immobile gas volume in solid and porous particle biofilter materials at low air flow velocities.

PubMed

Sharma, Prabhakar; Poulsen, Tjalfe G

2010-07-01

Gas-phase dispersion in granular biofilter materials with a wide range of particle sizes was investigated using atmospheric air and nitrogen as tracer gases. Two types of materials were used: (1) light extended clay aggregates (LECA), consisting of highly porous particles, and (2) gravel, consisting of solid particles. LECA is a commercial material that is used for insulation, as a soil conditioner, and as a carrier material in biofilters for air cleaning. These two materials were selected to have approximately the same particle shape. Column gas transport experiments were conducted for both materials using different mean particle diameters, different particle size ranges, and different gas flow velocities. Measured breakthrough curves were modeled using the advection-dispersion equation modified for mass transfer between mobile and immobile gas phases. The results showed that gas dispersivity increased with increasing mean particle diameter for LECA but was independent of mean particle diameter for gravel. Gas dispersivity also increased with increasing particle size range for both media. Dispersivities in LECA were generally higher than for gravel. The mobile gas content in both materials increased with increasing gas flow velocity but it did not show any strong dependency on mean particle diameter or particle size range. The relative fraction of mobile gas compared with total porosity was highest for gravel and lowest for LECA likely because of its high internal porosity.

Spatial arrangement and size distribution of normal faults, Buckskin detachment upper plate, Western Arizona

NASA Astrophysics Data System (ADS)

Laubach, S. E.; Hundley, T. H.; Hooker, J. N.; Marrett, R. A.

2018-03-01

Fault arrays typically include a wide range of fault sizes and those faults may be randomly located, clustered together, or regularly or periodically located in a rock volume. Here, we investigate size distribution and spatial arrangement of normal faults using rigorous size-scaling methods and normalized correlation count (NCC). Outcrop data from Miocene sedimentary rocks in the immediate upper plate of the regional Buckskin detachment-low angle normal-fault, have differing patterns of spatial arrangement as a function of displacement (offset). Using lower size-thresholds of 1, 0.1, 0.01, and 0.001 m, displacements range over 5 orders of magnitude and have power-law frequency distributions spanning ∼ four orders of magnitude from less than 0.001 m to more than 100 m, with exponents of -0.6 and -0.9. The largest faults with >1 m displacement have a shallower size-distribution slope and regular spacing of about 20 m. In contrast, smaller faults have steep size-distribution slopes and irregular spacing, with NCC plateau patterns indicating imposed clustering. Cluster widths are 15 m for the 0.1-m threshold, 14 m for 0.01-m, and 1 m for 0.001-m displacement threshold faults. Results demonstrate normalized correlation count effectively characterizes the spatial arrangement patterns of these faults. Our example from a high-strain fault pattern above a detachment is compatible with size and spatial organization that was influenced primarily by boundary conditions such as fault shape, mechanical unit thickness and internal stratigraphy on a range of scales rather than purely by interaction among faults during their propagation.

Symmetry and scale orient Min protein patterns in shaped bacterial sculptures

NASA Astrophysics Data System (ADS)

Wu, Fabai; van Schie, Bas G. C.; Keymer, Juan E.; Dekker, Cees

2015-08-01

The boundary of a cell defines the shape and scale of its subcellular organization. However, the effects of the cell's spatial boundaries as well as the geometry sensing and scale adaptation of intracellular molecular networks remain largely unexplored. Here, we show that living bacterial cells can be ‘sculpted’ into defined shapes, such as squares and rectangles, which are used to explore the spatial adaptation of Min proteins that oscillate pole-to-pole in rod-shaped Escherichia coli to assist cell division. In a wide geometric parameter space, ranging from 2 × 1 × 1 to 11 × 6 × 1 μm3, Min proteins exhibit versatile oscillation patterns, sustaining rotational, longitudinal, diagonal, stripe and even transversal modes. These patterns are found to directly capture the symmetry and scale of the cell boundary, and the Min concentration gradients scale with the cell size within a characteristic length range of 3-6 μm. Numerical simulations reveal that local microscopic Turing kinetics of Min proteins can yield global symmetry selection, gradient scaling and an adaptive range, when and only when facilitated by the three-dimensional confinement of the cell boundary. These findings cannot be explained by previous geometry-sensing models based on the longest distance, membrane area or curvature, and reveal that spatial boundaries can facilitate simple molecular interactions to result in far more versatile functions than previously understood.

Event-related potentials during word mapping to object shape predict toddlers' vocabulary size

PubMed Central

Borgström, Kristina; Torkildsen, Janne von Koss; Lindgren, Magnus

2015-01-01

What role does attention to different object properties play in early vocabulary development? This longitudinal study using event-related potentials in combination with behavioral measures investigated 20- and 24-month-olds' (n = 38; n = 34; overlapping n = 24) ability to use object shape and object part information in word-object mapping. The N400 component was used to measure semantic priming by images containing shape or detail information. At 20 months, the N400 to words primed by object shape varied in topography and amplitude depending on vocabulary size, and these differences predicted productive vocabulary size at 24 months. At 24 months, when most of the children had vocabularies of several hundred words, the relation between vocabulary size and the N400 effect in a shape context was weaker. Detached object parts did not function as word primes regardless of age or vocabulary size, although the part-objects were identified behaviorally. The behavioral measure, however, also showed relatively poor recognition of the part-objects compared to the shape-objects. These three findings provide new support for the link between shape recognition and early vocabulary development. PMID:25762957

Determining the composition of gold nanoparticles: a compilation of shapes, sizes, and calculations using geometric considerations.

PubMed

Mori, Taizo; Hegmann, Torsten

2016-01-01

Size, shape, overall composition, and surface functionality largely determine the properties and applications of metal nanoparticles. Aside from well-defined metal clusters, their composition is often estimated assuming a quasi-spherical shape of the nanoparticle core. With decreasing diameter of the assumed circumscribed sphere, particularly in the range of only a few nanometers, the estimated nanoparticle composition increasingly deviates from the real composition, leading to significant discrepancies between anticipated and experimentally observed composition, properties, and characteristics. We here assembled a compendium of tables, models, and equations for thiol-protected gold nanoparticles that will allow experimental scientists to more accurately estimate the composition of their gold nanoparticles using TEM image analysis data. The estimates obtained from following the routines described here will then serve as a guide for further analytical characterization of as-synthesized gold nanoparticles by other bulk (thermal, structural, chemical, and compositional) and surface characterization techniques. While the tables, models, and equations are dedicated to gold nanoparticles, the composition of other metal nanoparticle cores with face-centered cubic lattices can easily be estimated simply by substituting the value for the radius of the metal atom of interest.

Physical Explanation of Archie's Porosity Exponent in Granular Materials: A Process-Based, Pore-Scale Numerical Study

NASA Astrophysics Data System (ADS)

Niu, Qifei; Zhang, Chi

2018-02-01

The empirical Archie's law has been widely used in geosciences and engineering to explain the measured electrical resistivity of many geological materials, but its physical basis has not been fully understood yet. In this study, we use a pore-scale numerical approach combining discrete element-finite difference methods to study Archie's porosity exponent m of granular materials over a wide porosity range. Numerical results reveal that at dilute states (e.g., porosity ϕ > 65%), m is exclusively related to the particle shape and orientation. As the porosity decreases, the electric flow in pore space concentrates progressively near particle contacts and m increases continuously in response to the intensified nonuniformity of the local electrical field. It is also found that the increase in m is universally correlated with the volume fraction of pore throats for all the samples regardless of their particle shapes, particle size range, and porosities.

Transport and Deposition of Welding Fume Agglomerates in a Realistic Human Nasal Airway.

PubMed

Tian, Lin; Inthavong, Kiao; Lidén, Göran; Shang, Yidan; Tu, Jiyuan

2016-07-01

Welding fume is a complex mixture containing ultra-fine particles in the nanometer range. Rather than being in the form of a singular sphere, due to the high particle concentration, welding fume particles agglomerate into long straight chains, branches, or other forms of compact shapes. Understanding the transport and deposition of these nano-agglomerates in human respiratory systems is of great interest as welding fumes are a known health hazard. The neurotoxin manganese (Mn) is a common element in welding fumes. Particulate Mn, either as soluble salts or oxides, that has deposited on the olfactory mucosa in human nasal airway is transported along the olfactory nerve to the olfactory bulb within the brain. If this Mn is further transported to the basal ganglia of the brain, it could accumulate at the part of the brain that is the focal point of its neurotoxicity. Accounting for various dynamic shape factors due to particle agglomeration, the current computational study is focused on the exposure route, the deposition pattern, and the deposition efficiency of the inhaled welding fume particles in a realistic human nasal cavity. Particular attention is given to the deposition pattern and deposition efficiency of inhaled welding fume agglomerates in the nasal olfactory region. For particles in the nanoscale, molecular diffusion is the dominant transport mechanism. Therefore, Brownian diffusion, hydrodynamic drag, Saffman lift force, and gravitational force are included in the model study. The deposition efficiencies for single spherical particles, two kinds of agglomerates of primary particles, two-dimensional planar and straight chains, are investigated for a range of primary particle sizes and a range of number of primary particles per agglomerate. A small fraction of the inhaled welding fume agglomerates is deposited on the olfactory mucosa, approximately in the range 0.1-1%, and depends on particle size and morphology. The strong size dependence of the deposition in olfactory mucosa on particle size implies that the occupation deposition of welding fume manganese can be expected to vary with welding method. © The Author 2016. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Measurement of Size-dependent Dynamic Shape Factors of Quartz Particles in Two Flow Regimes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexander, Jennifer M.; Bell, David M.; Imre, D.

2016-08-02

Understanding and modeling the behavior of quartz dust particles, commonly found in the atmosphere, requires knowledge of many relevant particles properties, including particle shape. This study uses a single particle mass spectrometer, a differential mobility analyzer, and an aerosol particle mass analyzer to measure quartz aerosol particles mobility, aerodynamic, and volume equivalent diameters, mass, composition, effective density, and dynamic shape factor as a function of particle size, in both the free molecular and transition flow regimes. The results clearly demonstrate that dynamic shape factors can vary significantly as a function of particle size. For the quartz samples studied here, themore » dynamic shape factors increase with size, indicating that larger particles are significantly more aspherical than smaller particles. In addition, dynamic shape factors measured in the free-molecular (χv) and transition (χt) flow regimes can be significantly different, and these differences vary with the size of the quartz particles. For quartz, χv of small (d < 200 nm) particles is 1.25, while χv of larger particles (d ~ 440 nm) is 1.6, with a continuously increasing trend with particle size. In contrast χt, of small particles starts at 1.1 increasing slowly to 1.34 for 550 nm diameter particles. The multidimensional particle characterization approach used here goes beyond determination of average properties for each size, to provide additional information about how the particle dynamic shape factor may vary even for particles with the same mass and volume equivalent diameter.« less

The use of impact force as a scale parameter for the impact response of composite laminates

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Poe, C. C., Jr.

1992-01-01

The building block approach is currently used to design composite structures. With this approach, the data from coupon tests is scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low velocity impacts where the mass of the impacter is large and the size of the specimen is small. For large mass impacts of moderately thick (0.35 to 0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large mass test results can be applied directly to other plates of the same size.

Effect of the solvent on the size of clay nanoparticles in solution as determined using an ultraviolet-visible (UV-Vis) spectroscopy methodology.

PubMed

Alin, Jonas; Rubino, Maria; Auras, Rafael

2015-06-01

Ultraviolet-visible (UV-Vis) spectroscopy methodology was developed and utilized for the in situ nanoscale measurement of the size of mineral clay agglomerates in various liquid suspensions. The clays studied were organomodified and unmodified montmorillonite clays (I.44p, Cloisite 93a, and PGN). The methodology was compared and validated against dynamic light scattering (DLS) analysis. The method was able to measure clay agglomerates in solvents in situations where DLS analysis was unsuccessful due to the shapes, polydispersity, and high aspect ratios of the clay particles and the complexity of the aggregates, or dispersion medium. The measured clay agglomerates in suspension were found to be in the nanometer range in the more compatible solvents, and their sizes correlated with the Hansen solubility parameter space distance between the clay modifiers and the solvents. Mass detection limits for size determination were in the range from 1 to 9 mg/L. The methodology thus provides simple, rapid, and inexpensive characterization of clays or particles in the nano- or microsize range in low concentrations in various liquid media, including complex mixtures or highly viscous fluids that are difficult to analyze with DLS. In addition, by combining UV-VIS spectroscopy with DLS it was possible to discern flocculation behavior in liquids, which otherwise could result in false size measurements by DLS alone.

Robust functional statistics applied to Probability Density Function shape screening of sEMG data.

PubMed

Boudaoud, S; Rix, H; Al Harrach, M; Marin, F

2014-01-01

Recent studies pointed out possible shape modifications of the Probability Density Function (PDF) of surface electromyographical (sEMG) data according to several contexts like fatigue and muscle force increase. Following this idea, criteria have been proposed to monitor these shape modifications mainly using High Order Statistics (HOS) parameters like skewness and kurtosis. In experimental conditions, these parameters are confronted with small sample size in the estimation process. This small sample size induces errors in the estimated HOS parameters restraining real-time and precise sEMG PDF shape monitoring. Recently, a functional formalism, the Core Shape Model (CSM), has been used to analyse shape modifications of PDF curves. In this work, taking inspiration from CSM method, robust functional statistics are proposed to emulate both skewness and kurtosis behaviors. These functional statistics combine both kernel density estimation and PDF shape distances to evaluate shape modifications even in presence of small sample size. Then, the proposed statistics are tested, using Monte Carlo simulations, on both normal and Log-normal PDFs that mimic observed sEMG PDF shape behavior during muscle contraction. According to the obtained results, the functional statistics seem to be more robust than HOS parameters to small sample size effect and more accurate in sEMG PDF shape screening applications.

Three-dimensional reconstruction of the size and shape of protein microcrystals using Bragg coherent diffractive imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coughlan, H. D.; Darmanin, C.; Kirkwood, H. J.

2016-03-14

Three-dimensional imaging of protein crystals during X-ray diffraction experiments opens up a range of possibilities for optimising crystal quality and gaining new insights into the fundamental processes that drive radiation damage. Obtaining this information at the appropriate lengthscales however is extremely challenging. One approach that has been recently demonstrated as a promising avenue for charactering the size and shape of protein crystals at nanometre lengthscales is Bragg Coherent Diffractive Imaging (BCDI). BCDI is a recently developed technique that is able to recover the phase of the continuous diffraction intensity signal around individual Bragg peaks. When data is collected at multiplemore » points on a rocking curve a Reciprocal Space Map (RSM) can be assembled and then inverted using BCDI to obtain a three-dimensional image of the crystal. The first demonstration of two-dimensional BCDI of protein crystals was reported by Boutet at al., recently this work was extended to the study of radiation damage of micron-sized crystals. Here we present the first three-dimensional reconstructions of a Lysozyme protein crystal using BDI. The results are validated against RSM and TEM data and have implications for both radiation damage studies and for developing new approaches to structure retrieval from micron-sized protein crystals.« less

Hydrothermal synthesis of zinc oxide nanoparticles using rice as soft biotemplate.

PubMed

Ramimoghadam, Donya; Bin Hussein, Mohd Zobir; Taufiq-Yap, Yun Hin

2013-01-01

Rice as a renewable, abundant bio-resource with unique characteristics can be used as a bio-template to synthesize various functional nanomaterials. Therefore, the effect of uncooked rice flour as bio-template on physico-chemical properties, especially the morphology of zinc oxide nanostructures was investigated in this study. The ZnO particles were synthesized through hydrothermal-biotemplate method using zinc acetate-sodium hydroxide and uncooked rice flour at various ratios as precursors at 120°C for 18 hours. The results indicate that rice as a bio-template can be used to modify the shape and size of zinc oxide particles. Different morphologies, namely flake-, flower-, rose-, star- and rod-like structures were obtained with particle size at micro- and nanometer range. Pore size and texture of the resulting zinc oxide particles were found to be template-dependent and the resulting specific surface area enhanced compared to the zinc oxide synthesized without rice under the same conditions. However, optical property particularly the band gap energy is generally quite similar. Pure zinc oxide crystals were successfully synthesized using rice flour as biotemplate at various ratios of zinc salt to rice. The size- and shape-controlled capability of rice to assemble the ZnO particles can be employed for further useful practical applications.

Getting in shape: molten wax drop deformation and solidification at an immiscible liquid interface.

PubMed

Beesabathuni, Shilpa N; Lindberg, Seth E; Caggioni, Marco; Wesner, Chris; Shen, Amy Q

2015-05-01

The controlled production of non-spherical shaped particles is important for many applications such as food processing, consumer goods, adsorbents, drug delivery, and optical sensing. In this paper, we investigated the deformation and simultaneous solidification of millimeter size molten wax drops as they impacted an immiscible liquid interface of higher density. By varying initial temperature and viscoelasticity of the molten drop, drop size, impact velocity, viscosity and temperature of the bath fluid, and the interfacial tension between the molten wax and bath fluid, spherical molten wax drops impinged on a cooling water bath and were arrested into non-spherical solidified particles in the form of ellipsoid, mushroom, disc, and flake-like shapes. We constructed cursory phase diagrams for the various particle shapes generated over a range of Weber, Capillary, Reynolds, and Stefan numbers, governed by the interfacial, inertial, viscous, and thermal effects. We solved a simplified heat transfer problem to estimate the time required to initiate the solidification at the interface of a spherical molten wax droplet and cooling aqueous bath after impact. By correlating this time with the molten wax drop deformation history captured from high speed imaging experiments, we elucidate the delicate balance of interfacial, inertial, viscous, and thermal forces that determine the final morphology of wax particles. Copyright © 2015 Elsevier Inc. All rights reserved.

Accuracy Assessments of Cloud Droplet Size Retrievals from Polarized Reflectance Measurements by the Research Scanning Polarimeter

NASA Technical Reports Server (NTRS)

Alexandrov, Mikhail Dmitrievic; Cairns, Brian; Emde, Claudia; Ackerman, Andrew S.; vanDiedenhove, Bastiaan

2012-01-01

We present an algorithm for the retrieval of cloud droplet size distribution parameters (effective radius and variance) from the Research Scanning Polarimeter (RSP) measurements. The RSP is an airborne prototype for the Aerosol Polarimetery Sensor (APS), which was on-board of the NASA Glory satellite. This instrument measures both polarized and total reflectance in 9 spectral channels with central wavelengths ranging from 410 to 2260 nm. The cloud droplet size retrievals use the polarized reflectance in the scattering angle range between 135deg and 165deg, where they exhibit the sharply defined structure known as the rain- or cloud-bow. The shape of the rainbow is determined mainly by the single scattering properties of cloud particles. This significantly simplifies both forward modeling and inversions, while also substantially reducing uncertainties caused by the aerosol loading and possible presence of undetected clouds nearby. In this study we present the accuracy evaluation of our algorithm based on the results of sensitivity tests performed using realistic simulated cloud radiation fields.

Influence of surfactants on depsipeptide submicron particle formation.

PubMed

Brunacci, Nadia; Wischke, Christian; Naolou, Toufik; Neffe, Axel T; Lendlein, Andreas

2017-07-01

Surfactants are required for the formation and stabilization of hydrophobic polymeric particles in aqueous environment. In order to form submicron particles of varying sizes from oligo[3-(S)-sec-butylmorpholine-2,5-dione]diols ((OBMD)-diol), different surfactants were investigated. As new surfactants, four-armed star-shaped oligo(ethylene glycol)s of molecular weights of 5-20kDa functionalized with desamino-tyrosine (sOEG-DAT) resulted in smaller particles with lower PDI than with desaminotyrosyl tyrosine (sOEG-DATT) in an emulsion/solvent evaporation method. In a second set of experiments, sOEG-DAT of M n =10kDa was compared with the commonly employed emulsifiers polyvinylalcohol (PVA), polyoxyethylene (20) sorbitan monolaurate (Tween 20), and D-α-tocopherol polyethylene glycol succinate (VIT E-TPGS) for OBMD particle preparation. sOEG-DAT allowed to systematically change sizes in a range of 300 up to 900nm with narrow polydispersity, while in the other cases, a lower size range (250-400nm, PVA; ∼300nm, Tween 20) or no effective particle formation was observed. The ability of tailoring particle size in a broad range makes sOEG-DAT of particular interest for the formation of oligodepsipeptide particles, which can further be investigated as drug carriers for controlled delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

Wing shape and size of the western corn rootworm (Coleoptera: Chrysomelidae) is related to sex and resistance to soybean-maize crop rotation.

PubMed

Mikac, K M; Douglas, J; Spencer, J L

2013-08-01

The western corn rootworm, Diabrotica virgifera virgifera LeConte, is a major pest of maize in the United States and more recently, Europe. Understanding the dispersal dynamics of this species will provide crucial information for its management. This study used geometric morphometric analysis of hind wing venation based on 13 landmarks in 223 specimens from nine locations in Illinois, Nebraska, Iowa, and Missouri, to assess whether wing shape and size differed between rotated and continuously grown maize where crop rotation-resistant and susceptible individuals are found, respectively. Before assessing differences between rotation-resistant and susceptible individuals, sexual dimorphism was investigated. No significant difference in wing (centroid) size was found between males and females; however, females had significantly different shaped (more elongated) wings compared with males. Wing shape and (centroid) size were significantly larger among individuals from rotated maize where crop-rotation resistance was reported; however, cross-validation of these results revealed that collection site resistance status was an only better than average predictor of shape in males and females. This study provides preliminary evidence of wing shape and size differences in D. v. virgifera from rotated versus continuous maize. Further study is needed to confirm whether wing shape and size can be used to track the movement of rotation-resistant individuals and populations as a means to better inform management strategies.

Impact of the definition of peak standardized uptake value on quantification of treatment response.

PubMed

Vanderhoek, Matt; Perlman, Scott B; Jeraj, Robert

2012-01-01

PET-based treatment response assessment typically measures the change in maximum standardized uptake value (SUV(max)), which is adversely affected by noise. Peak SUV (SUV(peak)) has been recommended as a more robust alternative, but its associated region of interest (ROI(peak)) is not uniquely defined. We investigated the impact of different ROI(peak) definitions on quantification of SUV(peak) and tumor response. Seventeen patients with solid malignancies were treated with a multitargeted receptor tyrosine kinase inhibitor resulting in a variety of responses. Using the cellular proliferation marker 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT), whole-body PET/CT scans were acquired at baseline and during treatment. (18)F-FLT-avid lesions (∼2/patient) were segmented on PET images, and tumor response was assessed via the relative change in SUV(peak). For each tumor, 24 different SUV(peaks) were determined by changing ROI(peak) shape (circles vs. spheres), size (7.5-20 mm), and location (centered on SUV(max) vs. placed in highest-uptake region), encompassing different definitions from the literature. Within each tumor, variations in the 24 SUV(peaks) and tumor responses were measured using coefficient of variation (CV), standardized deviation (SD), and range. For each ROI(peak) definition, a population average SUV(peak) and tumor response were determined over all tumors. A substantial variation in both SUV(peak) and tumor response resulted from changing the ROI(peak) definition. The variable ROI(peak) definition led to an intratumor SUV(peak) variation ranging from 49% above to 46% below the mean (CV, 17%) and an intratumor SUV(peak) response variation ranging from 49% above to 35% below the mean (SD, 9%). The variable ROI(peak) definition led to a population average SUV(peak) variation ranging from 24% above to 28% below the mean (CV, 14%) and a population average SUV(peak) response variation ranging from only 3% above to 3% below the mean (SD, 2%). The size of ROI(peak) caused more variation in intratumor response than did the location or shape of ROI(peak). Population average tumor response was independent of size, shape, and location of ROI(peak). Quantification of individual tumor response using SUV(peak) is highly sensitive to the ROI(peak) definition, which can significantly affect the use of SUV(peak) for assessment of treatment response. Clinical trials are necessary to compare the efficacy of SUV(peak) and SUV(max) for quantification of response to therapy.

SU-E-T-146: Beam Energy Spread Estimate Based On Bragg Peak Measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anferov, V; Derenchuk, V; Moore, R

2015-06-15

Purpose: ProNova is installing and commissioning a two room proton therapy system in Knoxville, TN. Beam energy out of the 230MeV cyclotron was measured on Jan 24, 2015. Cyclotron beam was delivered into a Zebra multi layered IC detector calibrated in terms of penetration range in water. The analysis of the measured Bragg peak determines penetration range in water which can be subsequently converted into proton beam energy. We extended this analysis to obtain an estimate of the beam energy spread out of the cyclotron. Methods: Using Monte Carlo simulations we established the correlation between Bragg peak shape parameters (widthmore » at 50% and 80% dose levels, distal falloff) and penetration range for a monoenergetic proton beam. For large uniform field impinging on a small area detector, we observed linear dependence of each Bragg peak parameter on beam penetration range as shown in Figure A. Then we studied how this correlation changes when the shape of Bragg peak is distorted by the beam focusing conditions. As shown in Figure B, small field size or diverging beam cause Bragg peak deformation predominantly in the proximal region. The distal shape of the renormalized Bragg peaks stays nearly constant. This excludes usage of Bragg peak width parameters for energy spread estimates. Results: The measured Bragg peaks had an average distal falloff of 4.86mm, which corresponds to an effective range of 35.5cm for a monoenergetic beam. The 32.7cm measured penetration range is 2.8cm less. Passage of a 230MeV proton beam through a 2.8cm thick slab of water results in a ±0.56MeV energy spread. As a final check, we confirmed agreement between shapes of the measured Bragg peak and one generated by Monte-Carlo code for proton beam with 0.56 MeV energy spread. Conclusion: Proton beam energy spread can be estimated using Bragg peak analysis.« less

Dispersal of Volcanic Ash on Mars: Ash Grain Shape Analysis

NASA Astrophysics Data System (ADS)

Langdalen, Z.; Fagents, S. A.; Fitch, E. P.

2017-12-01

Many ash dispersal models use spheres as ash-grain analogs in drag calculations. These simplifications introduce inaccuracies in the treatment of drag coefficients, leading to inaccurate settling velocities and dispersal predictions. Therefore, we are investigating the use of a range of shape parameters, calculated using grain dimensions, to derive a better representation of grain shape and effective grain cross-sectional area. Specifically, our goal is to apply our results to the modeling of ash deposition to investigate the proposed volcanic origin of certain fine-grained deposits on Mars. Therefore, we are documenting the dimensions and shapes of ash grains from terrestrial subplinian to plinian deposits, in eight size divisions from 2 mm to 16 μm, employing a high resolution optical microscope. The optical image capture protocol provides an accurate ash grain outline by taking multiple images at different focus heights prior to combining them into a composite image. Image composite mosaics are then processed through ImageJ, a robust scientific measurement software package, to calculate a range of dimensionless shape parameters. Since ash grains rotate as they fall, drag forces act on a changing cross-sectional area. Therefore, we capture images and calculate shape parameters of each grain positioned in three orthogonal orientations. We find that the difference between maximum and minimum aspect ratios of the three orientations of a given grain best quantifies the degree of elongation of that grain. However, the average aspect ratio calculated for each grain provides a good representation of relative differences among grains. We also find that convexity provides the best representation of surface irregularity. For both shape parameters, natural ash grains display notably different shape parameter values than sphere analogs. Therefore, Mars ash dispersal modeling that incorporates shape parameters will provide more realistic predictions of deposit extents because volcanic ash-grain morphologies differ substantially from simplified geometric shapes.

Shape Distribution of Fragments from Microsatellite Impact Tests

NASA Technical Reports Server (NTRS)

Liou, J.C.; Hanada, T.

2009-01-01

Fragment shape is an important factor for conducting reliable orbital debris damage assessments for critical space assets, such as the International Space Station. To date, seven microsatellite impact tests have been completed as part of an ongoing collaboration between Kyushu University and the NASA Orbital Debris Program Office. The target satellites ranged in size from 15 cm 15 cm 15 cm to 20 cm 20 cm 20 cm. Each target satellite was equipped with fully functional electronics, including circuits, battery, and transmitter. Solar panels and multi-layer insulation (MLI) were added to the target satellites of the last two tests. The impact tests were carried out with projectiles of different sizes and impact speeds. All fragments down to about 2 mm in size were collected and analyzed based on their three orthogonal dimensions, x, y, and z, where x is the longest dimension, y is the longest dimension in the plane perpendicular to x, and z is the longest dimension perpendicular to both x and y. Each fragment was also photographed and classified by shape and material composition. This data set serves as the basis of our effort to develop a fragment shape distribution. Two distinct groups can be observed in the x/y versus y/z distribution of the fragments. Objects in the first group typically have large x/y values. Many of them are needle-like objects originating from the fragmentation of carbon fiber reinforced plastic materials used to construct the satellites. Objects in the second group tend to have small x/y values, and many of them are box-like or plate-like objects, depending on their y/z values. Each group forms the corresponding peak in the x/y distribution. However, only one peak can be observed in the y/z distribution. These distributions and how they vary with size, material type, and impact parameters will be described in detail within the paper.

Facile one step synthesis of novel TiO2 nanocoral by sol-gel method using Aloe vera plant extract

NASA Astrophysics Data System (ADS)

Venkatesh, K. S.; Krishnamoorthi, S. R.; Palani, N. S.; Thirumal, V.; Jose, Sujin P.; Wang, Fu-Ming; Ilangovan, R.

2015-05-01

Titanium oxide (TiO2) nanoparticles (NPs) were synthesized by sol gel method using Aloe vera plant extract as a biological capping agent and a cauliflower-nanocoral morphology was observed in this technique. The assynthesized TiO2 nanopowder was calcined at a range of temperatures (300-600 °C) for 1 h. The influence of A. vera plant extract on the thermal, structural and morphological properties of TiO2 nanopowder was evaluated. Thermogravimetric analysis/differential thermal analysis was employed to study the thermal properties of the assynthesized TiO2 nanopowder. The crystallinity, phase transformation and the crystallite size of the calcined samples were studied by X-ray diffraction technique. XRD result confirmed the presence of TiO2 with anatase phase. FT Raman spectra showed the Raman active modes pertaining to the TiO2 anatase phase and Raman band shift was also observed with respect to particle size variation. The different functional group vibrations of as dried pure A. vera plant extract were compared with the mixture of TiO2 and A. vera plant extract by FT-IR analysis. The scanning electron microscopy images apparently showed the formation of spherical shaped NPs and also it demonstrated the effect of A. vera plant extract on the reduction of particles size. The surface area of the TiO2 NPs was measured through Brunauer-Emmett-Teller analysis. Transmission electron microscopy images ascertained that the spherical shaped TiO2 NPs were formed with cauliflower-nanocoral morphology decorated with nanopolyps with the size range between 15 and 30 nm.

Comparison between computed tomography and (99m)TC- pertechnetate scintigraphy characteristics of the thyroid gland in cats with hyperthyroidism.

PubMed

Lautenschlaeger, Ines E; Hartmann, Antje; Sicken, Julia; Mohrs, Sabrina; Scholz, Volkher B; Neiger, Reto; Kramer, Martin

2013-01-01

Scintigraphy is currently the reference standard for diagnosing feline hyperthyroidism; however, computed tomography (CT) is more widely available in veterinary practice. The purposes of this prospective study were to describe the CT appearance of thyroid glands in cats with hyperthyroidism and compare CT findings with findings from (99m) Tc-pertechnetate scintigraphy. Twenty-five adult hyperthyroid cats were included. Plain CT images were acquired for each cat and the following characteristics recorded for each thyroid lobe: visibility, delineation, position, attenuation, shape, and subjective size. Scintigraphic images were also acquired and the following characteristics recorded: radiopharmaceutical uptake, delineation, ectopic foci, shape, and subjective size. In CT images, thyroid lobes were most commonly found between the second and fourth cervical vertebrae, dorsolateral to the trachea. Affected thyroid lobes (based on scintigraphy reference standard) were most commonly oval and moderately enlarged in CT images. A heterogeneous attenuation pattern (isoattenuating to adjacent soft tissues with hypo- and hyperattenuating foci) was most commonly found in affected thyroid lobes. A positive correlation (P < 0.01) was identified between CT and scintigraphy for left-to-right thyroid lobe size relationship and subjective size of the larger thyroid lobe. The CT estimated mass was significantly higher (median = 148.8; range = [0;357.6]) for the more active thyroid lobe compared to the less active thyroid lobe (median = 84.6; range = [0;312.3]); (W = 154; P < 0.01). Findings indicated that CT may not reliably differentiate unilateral vs. bilateral hyperthyroidism in cats; however, CT may be a reliable alternative test for correctly identifying the more active thyroid lobe. © 2013 Veterinary Radiology & Ultrasound.

Size, shape and flow characterization of ground wood chip and ground wood pellet particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rezaei, Hamid; Lim, C. Jim; Lau, Anthony

Size, shape and density of biomass particles influence their transportation, fluidization, rates of drying and thermal decomposition. Pelleting wood particles increases the particle density and reduces the variability of physical properties among biomass particles. In this study, pine chips prepared for pulping and commercially produced pine pellets were ground in a hammer mill using grinder screens of 3.2, 6.3, 12.7 and 25.4mmperforations. Pellets consumed about 7 times lower specific grinding energy than chips to produce the same size of particles. Grinding pellets produced the smaller particles with narrower size distribution than grinding chips. Derived shape factors in digital image analysismore » showed that chip particles were rectangular and had the aspect ratios about one third of pellet particles. Pellet particles were more circular shape. The mechanical sieving underestimated the actual particle size and did not represent the size of particles correctly. Instead, digital imaging is preferred. Angle of repose and compressibility tests represented the flow properties of ground particles. Pellet particles made a less compacted bulk, had lower cohesion and did flow easier in a pile of particles. In conclusion, particle shape affected the flow properties more than particle size« less

Size, shape and flow characterization of ground wood chip and ground wood pellet particles

DOE PAGES

Rezaei, Hamid; Lim, C. Jim; Lau, Anthony; ...

2016-07-11

Size, shape and density of biomass particles influence their transportation, fluidization, rates of drying and thermal decomposition. Pelleting wood particles increases the particle density and reduces the variability of physical properties among biomass particles. In this study, pine chips prepared for pulping and commercially produced pine pellets were ground in a hammer mill using grinder screens of 3.2, 6.3, 12.7 and 25.4mmperforations. Pellets consumed about 7 times lower specific grinding energy than chips to produce the same size of particles. Grinding pellets produced the smaller particles with narrower size distribution than grinding chips. Derived shape factors in digital image analysismore » showed that chip particles were rectangular and had the aspect ratios about one third of pellet particles. Pellet particles were more circular shape. The mechanical sieving underestimated the actual particle size and did not represent the size of particles correctly. Instead, digital imaging is preferred. Angle of repose and compressibility tests represented the flow properties of ground particles. Pellet particles made a less compacted bulk, had lower cohesion and did flow easier in a pile of particles. In conclusion, particle shape affected the flow properties more than particle size« less

Complete grain boundaries from incomplete EBSD maps: the influence of segmentation on grain size determinations

NASA Astrophysics Data System (ADS)

Heilbronner, Renée; Kilian, Ruediger

2017-04-01

Grain size analyses are carried out for a number of reasons, for example, the dynamically recrystallized grain size of quartz is used to assess the flow stresses during deformation. Typically a thin section or polished surface is used. If the expected grain size is large enough (10 µm or larger), the images can be obtained on a light microscope, if the grain size is smaller, the SEM is used. The grain boundaries are traced (the process is called segmentation and can be done manually or via image processing) and the size of the cross sectional areas (segments) is determined. From the resulting size distributions, 'the grain size' or 'average grain size', usually a mean diameter or similar, is derived. When carrying out such grain size analyses, a number of aspects are critical for the reproducibility of the result: the resolution of the imaging equipment (light microscope or SEM), the type of images that are used for segmentation (cross polarized, partial or full orientation images, CIP versus EBSD), the segmentation procedure (algorithm) itself, the quality of the segmentation and the mathematical definition and calculation of 'the average grain size'. The quality of the segmentation depends very strongly on the criteria that are used for identifying grain boundaries (for example, angles of misorientation versus shape considerations), on pre- and post-processing (filtering) and on the quality of the recorded images (most notably on the indexing ratio). In this contribution, we consider experimentally deformed Black Hills quartzite with dynamically re-crystallized grain sizes in the range of 2 - 15 µm. We compare two basic methods of segmentations of EBSD maps (orientation based versus shape based) and explore how the choice of methods influences the result of the grain size analysis. We also compare different measures for grain size (mean versus mode versus RMS, and 2D versus 3D) in order to determine which of the definitions of 'average grain size yields the most stable results.

Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco

PubMed Central

Hollands, Gareth J; Shemilt, Ian; Marteau, Theresa M; Jebb, Susan A; Lewis, Hannah B; Wei, Yinghui; Higgins, Julian Pt; Ogilvie, David

2015-01-01

Background Overeating and harmful alcohol and tobacco use have been linked to the aetiology of various non-communicable diseases, which are among the leading global causes of morbidity and premature mortality. As people are repeatedly exposed to varying sizes and shapes of food, alcohol and tobacco products in environments such as shops, restaurants, bars and homes, this has stimulated public health policy interest in product size and shape as potential targets for intervention. Objectives 1) To assess the effects of interventions involving exposure to different sizes or sets of physical dimensions of a portion, package, individual unit or item of tableware on unregulated selection or consumption of food, alcohol or tobacco products in adults and children. 2) To assess the extent to which these effects may be modified by study, intervention and participant characteristics. Search methods We searched CENTRAL, MEDLINE, EMBASE, PsycINFO, eight other published or grey literature databases, trial registries and key websites up to November 2012, followed by citation searches and contacts with study authors. This original search identified eligible studies published up to July 2013, which are fully incorporated into the review. We conducted an updated search up to 30 January 2015 but further eligible studies are not yet fully incorporated due to their minimal potential to change the conclusions. Selection criteria Randomised controlled trials with between-subjects (parallel-group) or within-subjects (cross-over) designs, conducted in laboratory or field settings, in adults or children. Eligible studies compared at least two groups of participants, each exposed to a different size or shape of a portion of a food (including non-alcoholic beverages), alcohol or tobacco product, its package or individual unit size, or of an item of tableware used to consume it, and included a measure of unregulated selection or consumption of food, alcohol or tobacco. Data collection and analysis We applied standard Cochrane methods to select eligible studies for inclusion and to collect data and assess risk of bias. We calculated study-level effect sizes as standardised mean differences (SMDs) between comparison groups, measured as quantities selected or consumed. We combined these results using random-effects meta-analysis models to estimate summary effect sizes (SMDs with 95% confidence intervals (CIs)) for each outcome for size and shape comparisons. We rated the overall quality of evidence using the GRADE system. Finally, we used meta-regression analysis to investigate statistical associations between summary effect sizes and variant study, intervention or participant characteristics. Main results The current version of this review includes 72 studies, published between 1978 and July 2013, assessed as being at overall unclear or high risk of bias with respect to selection and consumption outcomes. Ninety-six per cent of included studies (69/72) manipulated food products and 4% (3/72) manipulated cigarettes. No included studies manipulated alcohol products. Forty-nine per cent (35/72) manipulated portion size, 14% (10/72) package size and 21% (15/72) tableware size or shape. More studies investigated effects among adults (76% (55/72)) than children and all studies were conducted in high-income countries - predominantly in the USA (81% (58/72)). Sources of funding were reported for the majority of studies, with no evidence of funding by agencies with possible commercial interests in their results. A meta-analysis of 86 independent comparisons from 58 studies (6603 participants) found a small to moderate effect of portion, package, individual unit or tableware size on consumption of food (SMD 0.38, 95% CI 0.29 to 0.46), providing moderate quality evidence that exposure to larger sizes increased quantities of food consumed among children (SMD 0.21, 95% CI 0.10 to 0.31) and adults (SMD 0.46, 95% CI 0.40 to 0.52). The size of this effect suggests that, if sustained reductions in exposure to larger-sized food portions, packages and tableware could be achieved across the whole diet, this could reduce average daily energy consumed from food by between 144 and 228 kcal (8.5% to 13.5% from a baseline of 1689 kcal) among UK children and adults. A meta-analysis of six independent comparisons from three studies (108 participants) found low quality evidence for no difference in the effect of cigarette length on consumption (SMD 0.25, 95% CI -0.14 to 0.65). One included study (50 participants) estimated a large effect on consumption of exposure to differently shaped tableware (SMD 1.17, 95% CI 0.57 to 1.78), rated as very low quality evidence that exposure to shorter, wider bottles (versus taller, narrower bottles) increased quantities of water consumed by young adult participants. A meta-analysis of 13 independent comparisons from 10 studies (1164 participants) found a small to moderate effect of portion or tableware size on selection of food (SMD 0.42, 95% CI 0.24 to 0.59), rated as moderate quality evidence that exposure to larger sizes increased the quantities of food people selected for subsequent consumption. This effect was present among adults (SMD 0.55, 95% CI 0.35 to 0.75) but not children (SMD 0.14, 95% CI -0.06 to 0.34). In addition, a meta-analysis of three independent comparisons from three studies (232 participants) found a very large effect of exposure to differently shaped tableware on selection of non-alcoholic beverages (SMD 1.47, 95% CI 0.52 to 2.43), rated as low quality evidence that exposure to shorter, wider (versus taller, narrower) glasses or bottles increased the quantities selected for subsequent consumption among adults (SMD 2.31, 95% CI 1.79 to 2.83) and children (SMD 1.03, 95% CI 0.41 to 1.65). Authors' conclusions This review found that people consistently consume more food and drink when offered larger-sized portions, packages or tableware than when offered smaller-sized versions. This suggests that policies and practices that successfully reduce the size, availability and appeal of larger-sized portions, packages, individual units and tableware can contribute to meaningful reductions in the quantities of food (including non-alcoholic beverages) people select and consume in the immediate and short term. However, it is uncertain whether reducing portions at the smaller end of the size range can be as effective in reducing food consumption as reductions at the larger end of the range. We are unable to highlight clear implications for tobacco or alcohol policy due to identified gaps in the current evidence base. PLAIN LANGUAGE SUMMARY Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco Review question We reviewed the evidence to establish by how much the amounts of food, alcohol or tobacco adults and children select or consume change in response to being presented with larger or smaller-sized (or differently shaped) portions or packages of these products, or of items of tableware (such as plates or glasses) used to consume them. Study characteristics This review includes 72 randomised controlled trials (RCTs) published up to July 2013 that compared at least two groups of participants, each presented with a different size of a portion, package or item of tableware. Included studies measured the amounts of food, alcohol or tobacco selected and/or consumed by participants, typically over a period of one day or less. Almost all of the included studies investigated food, with only three tobacco studies and no alcohol studies found. Almost all assessed participants' responses to different sizes rather than different shapes. The average age of participants in the different studies ranged from three to 55 years, with more studies involving adults than children and most conducted in the USA. Sources of funding were reported for the majority of studies and there was no evidence of study funding by agencies with commercial interests in their results. Key findings and quality of evidence Effects of size on consumption: We found evidence that people consistently ate more food or drank more non-alcoholic drinks when offered larger-sized portions, packages or items of tableware than when offered smaller-sized versions. We estimate the size of this effect to be small to moderate among both children and adults. If an effect of this size were sustained across the whole diet it would be equivalent to around a 12% to 16% change in average daily energy intake from food among UK adults. We rated the overall quality of the evidence for this effect as moderate, due to concern about study limitations arising from incomplete or unclear reporting of methods and procedures. From three tobacco studies, we found no effect of longer compared with shorter cigarettes on the amounts of tobacco consumed. We rated the overall quality of evidence for this effect as low due to concerns about study limitations and not having enough evidence. Effects of shape on consumption: One study found that adults provided with shorter, wider bottles drank larger amounts of water from them, having already poured more, compared with those provided with taller, narrower bottles. However, we rated the quality of this evidence as very low, due to very serious concerns about study limitations and not having enough evidence (only one study with outcome data from 50 participants). Effects of size on selection: We further found that adults, but not children, consistently chose (selected) more food (including non-alcoholic drinks) when offered larger-sized portions, packages or items of tableware than when offered smaller-sized versions. The estimated size of this effect was again small to moderate. We rated the overall quality of the evidence for this effect as moderate, due to concern about study limitations. Effects of shape on selection: Evidence from three studies suggested that adults and children provided with shorter, wider bottles or glasses selected increased quantities of non-alcoholic beverages for subsequent consumption, compared with those provided with taller, narrower bottles or glasses. We rated the quality of this evidence as low, again due to concerns about study limitations and unexplained variation in effects between the three studies. Conclusions Overall, this review provides the most conclusive evidence to date that acting to reduce the size, availability and appeal of larger-sized portions, packages and tableware has potential to reduce the quantities of food that people select and consume by meaningful amounts. However, it is uncertain whether reducing portions at the smaller end of the size range can be as effective in reducing food consumption as reductions at the larger end of the range. Our findings highlight the need for further research that aims to reduce uncertainties about these effects and address identified gaps in the evidence base, including not having enough evidence for longer-term effects and the absence of evidence about alcohol products. PMID:26368271

Can SNOMED CT be squeezed without losing its shape?

PubMed

López-García, Pablo; Schulz, Stefan

2016-09-21

In biomedical applications where the size and complexity of SNOMED CT become problematic, using a smaller subset that can act as a reasonable substitute is usually preferred. In a special class of use cases-like ontology-based quality assurance, or when performing scaling experiments for real-time performance-it is essential that modules show a similar shape than SNOMED CT in terms of concept distribution per sub-hierarchy. Exactly how to extract such balanced modules remains unclear, as most previous work on ontology modularization has focused on other problems. In this study, we investigate to what extent extracting balanced modules that preserve the original shape of SNOMED CT is possible, by presenting and evaluating an iterative algorithm. We used a graph-traversal modularization approach based on an input signature. To conform to our definition of a balanced module, we implemented an iterative algorithm that carefully bootstraped and dynamically adjusted the signature at each step. We measured the error for each sub-hierarchy and defined convergence as a residual sum of squares <1. Using 2000 concepts as an initial signature, our algorithm converged after seven iterations and extracted a module 4.7 % the size of SNOMED CT. Seven sub-hierarhies were either over or under-represented within a range of 1-8 %. Our study shows that balanced modules from large terminologies can be extracted using ontology graph-traversal modularization techniques under certain conditions: that the process is repeated a number of times, the input signature is dynamically adjusted in each iteration, and a moderate under/over-representation of some hierarchies is tolerated. In the case of SNOMED CT, our results conclusively show that it can be squeezed to less than 5 % of its size without any sub-hierarchy losing its shape more than 8 %, which is likely sufficient in most use cases.

The possibility of using photogrammetric and remote sensing techniques to model lavaka (gully erosion) development in Madagascar

NASA Astrophysics Data System (ADS)

Raveloson, Andrea; Székely, Balázs; Molnár, Gábor; Rasztovits, Sascha

2013-04-01

Gully erosion is a worldwide problem for it has a number of undesirable effects and their development is hard to follow. Madagascar is one of the most affected countries for its highlands are densely covered with gullies named lavakas. Lavaka formation and development seems to be triggered by many regional and local causes but the actual reasons are still poorly understood. Furthermore lavakas differ from normal gullies due to their enormous size and special shape. Field surveys are time consuming and data from two-dimensional measurements and pictures (even aerial) might lack major information for morphologic studies. Therefore close range surveying technologies should be used to get three-dimensional information about these unusual and complex features. This contribution discusses which remote sensing and photogrammetric techniques are adequate to survey the development of lavakas, their volume change and sediment budget. Depending on the types and properties (such as volume, depth, shape, vegetation) of the lavaka different methods will be proposed showing pros and cons of each one of them. Our goal is to review techniques to model, survey and analyze lavakas development to better understand the cause of their formation, special size and shape. Different methods are evaluated and compared from field survey through data processing, analyzing cost-effectiveness, potential errors and accuracy for each one of them. For this purpose we will also consider time- and cost-effectiveness of the softwares able to render the images into 3D model as well as the resolution and accuracy of the outputs. Further studies will concentrate on using the three dimensional models of lavakas which will be later on used for geomorphological studies in order to understand their special shape and size. This is ILARG-contribution #07.

Shape of boulders ejected from small lunar impact craters

NASA Astrophysics Data System (ADS)

Li, Yuan; Basilevsky, A. T.; Xie, Minggang; Ip, Wing-Huen

2017-10-01

The shape of ejecta boulders from 7 lunar impact craters <1 km in diameter of known absolute age was measured to explore whether it correlates with the crater age and the boulder size. The boulders were mapped and then measured by rectangular fitting and the shape was represented by the axial ratio or aspect ratio (A) of the rectangle. The main conclusions from the analysis of our measurement results are: 1) the percentages of the number of boulders of studied craters decrease with the increase of the axial ratio. Most (∼90%) of the boulders have the axial ratio in the range of 1-2; no boulder with axial ratio larger than 4 was found. 2) the axial ratios of mare ejecta boulders decrease with their exposure time, whereas that for highland ones show unchanged trend. This difference may be probably due to target properties. 3) The shape of ejecta boulders are influenced by mechanical strength of bedrocks and space erosion. 4) surface peak stresses caused by thermal fatigue maybe play a significant erosion role in the shape of boulders of various diameter.

Shape and size variation on the wing of Drosophila mediopunctata: influence of chromosome inversions and genotype-environment interaction.

PubMed

Hatadani, Luciane Mendes; Klaczko, Louis Bernard

2008-07-01

The second chromosome of Drosophila mediopunctata is highly polymorphic for inversions. Previous work reported a significant interaction between these inversions and collecting date on wing size, suggesting the presence of genotype-environment interaction. We performed experiments in the laboratory to test for the joint effects of temperature and chromosome inversions on size and shape of the wing in D. mediopunctata. Size was measured as the centroid size, and shape was analyzed using the generalized least squares Procrustes superimposition followed by discriminant analysis and canonical variates analysis of partial warps and uniform components scores. Our findings show that wing size and shape are influenced by temperature, sex, and karyotype. We also found evidence suggestive of an interaction between the effects of karyotype and temperature on wing shape, indicating the existence of genotype-environment interaction for this trait in D. mediopunctata. In addition, the association between wing size and chromosome inversions is in agreement with previous results indicating that these inversions might be accumulating alleles adapted to different temperatures. However, no significant interaction between temperature and karyotype for size was found--in spite of the significant presence of temperature-genotype (cross) interaction. We suggest that other ecological factors--such as larval crowding--or seasonal variation of genetic content within inversions may explain the previous results.

Comparison of Two Methods Used to Model Shape Parameters of Pareto Distributions

USGS Publications Warehouse

Liu, C.; Charpentier, R.R.; Su, J.

2011-01-01

Two methods are compared for estimating the shape parameters of Pareto field-size (or pool-size) distributions for petroleum resource assessment. Both methods assume mature exploration in which most of the larger fields have been discovered. Both methods use the sizes of larger discovered fields to estimate the numbers and sizes of smaller fields: (1) the tail-truncated method uses a plot of field size versus size rank, and (2) the log-geometric method uses data binned in field-size classes and the ratios of adjacent bin counts. Simulation experiments were conducted using discovered oil and gas pool-size distributions from four petroleum systems in Alberta, Canada and using Pareto distributions generated by Monte Carlo simulation. The estimates of the shape parameters of the Pareto distributions, calculated by both the tail-truncated and log-geometric methods, generally stabilize where discovered pool numbers are greater than 100. However, with fewer than 100 discoveries, these estimates can vary greatly with each new discovery. The estimated shape parameters of the tail-truncated method are more stable and larger than those of the log-geometric method where the number of discovered pools is more than 100. Both methods, however, tend to underestimate the shape parameter. Monte Carlo simulation was also used to create sequences of discovered pool sizes by sampling from a Pareto distribution with a discovery process model using a defined exploration efficiency (in order to show how biased the sampling was in favor of larger fields being discovered first). A higher (more biased) exploration efficiency gives better estimates of the Pareto shape parameters. ?? 2011 International Association for Mathematical Geosciences.

Effect of amylose, particle size & morphology on the functionality of starches of traditional rice cultivars.

PubMed

Bhat, Farhan Mohiuddin; Riar, Charanjit Singh

2016-11-01

The research was carried out to investigate the effect of starch powder particle size, morphology, amylose content and varietal effect on physicochemical, X-ray diffraction pattern, thermal and pasting characteristics. The results indicated that starches isolated from seven traditional rice cultivars of temperate region of India have possessed higher yield (82.47-86.83%) with lower degree of granule damage and higher level of starch crystallinity (36.55-39.15%). The water and oil binding capacities were observed to correlate positively with amylose content. The bulk density and color parameters of starches were found to have linked with starch powder particle size coupled with arrangement and morphology of the starch granules. The rice cultivars having smaller starch powder particle size indicated lowest degree of crystallinity. Morphological studies revealed that the starches with tightly packed granules had greater mean granular width, while granules with openly spaced granular morphology depicted the higher values for mean granular length. The peak height index (PHI) among different starches ranged from 1.01 to 2.57 whereas the gelatinization range varied from 10.66 to 10.88. Concluding, the differences in distributional pattern of starch granule size and shape and powder particle size indicated a significant effect on the functional properties of starch. Copyright © 2016 Elsevier B.V. All rights reserved.

Evolution of spur-length diversity in Aquilegia petals is achieved solely through cell-shape anisotropy.

PubMed

Puzey, Joshua R; Gerbode, Sharon J; Hodges, Scott A; Kramer, Elena M; Mahadevan, L

2012-04-22

The role of petal spurs and specialized pollinator interactions has been studied since Darwin. Aquilegia petal spurs exhibit striking size and shape diversity, correlated with specialized pollinators ranging from bees to hawkmoths in a textbook example of adaptive radiation. Despite the evolutionary significance of spur length, remarkably little is known about Aquilegia spur morphogenesis and its evolution. Using experimental measurements, both at tissue and cellular levels, combined with numerical modelling, we have investigated the relative roles of cell divisions and cell shape in determining the morphology of the Aquilegia petal spur. Contrary to decades-old hypotheses implicating a discrete meristematic zone as the driver of spur growth, we find that Aquilegia petal spurs develop via anisotropic cell expansion. Furthermore, changes in cell anisotropy account for 99 per cent of the spur-length variation in the genus, suggesting that the true evolutionary innovation underlying the rapid radiation of Aquilegia was the mechanism of tuning cell shape.

Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

NASA Astrophysics Data System (ADS)

Jangid, K. G.; Choudhary, N.; Jain, P.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

2016-03-01

This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiation properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.

The effect of particle shape and size distribution on the acoustical properties of mixtures of hemp particles.

PubMed

Glé, Philippe; Gourdon, Emmanuel; Arnaud, Laurent; Horoshenkov, Kirill-V; Khan, Amir

2013-12-01

Hemp concrete is an attractive alternative to traditional materials used in building construction. It has a very low environmental impact, and it is characterized by high thermal insulation. Hemp aggregate particles are parallelepiped in shape and can be organized in a plurality of ways to create a considerable proportion of open pores with a complex connectivity pattern, the acoustical properties of which have never been examined systematically. Therefore this paper is focused on the fundamental understanding of the relations between the particle shape and size distribution, pore size distribution, and the acoustical properties of the resultant porous material mixture. The sound absorption and the transmission loss of various hemp aggregates is characterized using laboratory experiments and three theoretical models. These models are used to relate the particle size distribution to the pore size distribution. It is shown that the shape of particles and particle size control the pore size distribution and tortuosity in shiv. These properties in turn relate directly to the observed acoustical behavior.

Impact of Snow Grain Shape and Internal Mixing with Black Carbon Aerosol on Snow Optical Properties for use in Climate Models

NASA Astrophysics Data System (ADS)

He, C.; Liou, K. N.; Takano, Y.; Yang, P.; Li, Q.; Chen, F.

2017-12-01

A set of parameterizations is developed for spectral single-scattering properties of clean and black carbon (BC)-contaminated snow based on geometric-optic surface-wave (GOS) computations, which explicitly resolves BC-snow internal mixing and various snow grain shapes. GOS calculations show that, compared with nonspherical grains, volume-equivalent snow spheres show up to 20% larger asymmetry factors and hence stronger forward scattering, particularly at wavelengths <1 mm. In contrast, snow grain sizes have a rather small impact on the asymmetry factor at wavelengths <1 mm, whereas size effects are important at longer wavelengths. The snow asymmetry factor is parameterized as a function of effective size, aspect ratio, and shape factor, and shows excellent agreement with GOS calculations. According to GOS calculations, the single-scattering coalbedo of pure snow is predominantly affected by grain sizes, rather than grain shapes, with higher values for larger grains. The snow single-scattering coalbedo is parameterized in terms of the effective size that combines shape and size effects, with an accuracy of >99%. Based on GOS calculations, BC-snow internal mixing enhances the snow single-scattering coalbedo at wavelengths <1 mm, but it does not alter the snow asymmetry factor. The BC-induced enhancement ratio of snow single-scattering coalbedo, independent of snow grain size and shape, is parameterized as a function of BC concentration with an accuracy of >99%. Overall, in addition to snow grain size, both BC-snow internal mixing and snow grain shape play critical roles in quantifying BC effects on snow optical properties. The present parameterizations can be conveniently applied to snow, land surface, and climate models including snowpack radiative transfer processes.

Size and shape effects in β-NaGdF4: Yb3+, Er3+ nanocrystals

NASA Astrophysics Data System (ADS)

Noculak, Agnieszka; Podhorodecki, Artur

2017-04-01

Three sets of β-NaGdF4:Yb3+, Er3+ nanocrystals (NCs) with different shapes (spherical and more complex flower shapes), different sizes (6-17 nm) and Yb3+ concentrations (2%-15%) were synthesized by a co-precipitation method using oleic acid as a stabilizing agent. The uncommon, single-crystalline flower-shaped NCs were obtained by simply adjusting the fluorine-to-lanthanides molar ratio. Additionally, some of the NCs with different sizes have been covered by the un-doped shell. The crystal phase, shapes and sizes of all NCs were examined using transmission electron microscopy and x-ray diffraction methods. Simultaneously, upconversion luminescence and lifetimes, under 980 nm excitation, were measured and the changes in green to red (G/R) emission ratios as well as emission decay times were correlated with the evolution of nanocrystal sizes and surface to volume ratios. Three different mechanisms responsible for the changes in G/R ratios were presented and discussed.

Tuning structural motifs and alloying of bulk immiscible Mo-Cu bimetallic nanoparticles by gas-phase synthesis

NASA Astrophysics Data System (ADS)

Krishnan, Gopi; Verheijen, Marcel A.; Ten Brink, Gert H.; Palasantzas, George; Kooi, Bart J.

2013-05-01

Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still remains a formidable challenge. Hence, we present here a general methodology for gas phase synthesis of bimetallic NPs with distinctively different structural motifs ranging at a single particle level from a fully mixed alloy to core-shell, to onion (multi-shell), and finally to a Janus/dumbbell, with the same overall particle composition. These concepts are illustrated for Mo-Cu NPs, where the precise control of the bimetallic NPs with various degrees of chemical ordering, including different shapes from spherical to cube, is achieved by tailoring the energy and thermal environment that the NPs experience during their production. The initial state of NP growth, either in the liquid or in the solid state phase, has important implications for the different structural motifs and shapes of synthesized NPs. Finally we demonstrate that we are able to tune the alloying regime, for the otherwise bulk immiscible Mo-Cu, by achieving an increase of the critical size, below which alloying occurs, closely up to an order of magnitude. It is discovered that the critical size of the NP alloy is not only affected by controlled tuning of the alloying temperature but also by the particle shape.Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still remains a formidable challenge. Hence, we present here a general methodology for gas phase synthesis of bimetallic NPs with distinctively different structural motifs ranging at a single particle level from a fully mixed alloy to core-shell, to onion (multi-shell), and finally to a Janus/dumbbell, with the same overall particle composition. These concepts are illustrated for Mo-Cu NPs, where the precise control of the bimetallic NPs with various degrees of chemical ordering, including different shapes from spherical to cube, is achieved by tailoring the energy and thermal environment that the NPs experience during their production. The initial state of NP growth, either in the liquid or in the solid state phase, has important implications for the different structural motifs and shapes of synthesized NPs. Finally we demonstrate that we are able to tune the alloying regime, for the otherwise bulk immiscible Mo-Cu, by achieving an increase of the critical size, below which alloying occurs, closely up to an order of magnitude. It is discovered that the critical size of the NP alloy is not only affected by controlled tuning of the alloying temperature but also by the particle shape. Electronic supplementary information (ESI) available: Experimental details including schematics of the gas phase synthesis set up, target arrangement, synthesis condition for various structures, and TEM images of alloy, core-shell and Mo-Cu-Mo onion nanoparticles. See DOI: 10.1039/c3nr00565h

Two-Photon Microscopy Analysis of Gold Nanoparticle Uptake in 3D Cell Spheroids.

PubMed

Rane, Tushar D; Armani, Andrea M

2016-01-01

Nanomaterials can be synthesized from a wide range of material systems in numerous morphologies, creating an extremely diverse portfolio. As result of this tunability, these materials are emerging as a new class of nanotherapeutics and imaging agents. One particularly interesting nanomaterial is the gold nanoparticle. Due to its inherent biocompatibility and tunable photothermal behavior, it has made a rapid transition from the lab setting to in vivo testing. In most nanotherapeutic applications, the efficacy of the agent is directly related to the target of interest. However, the optimization of the AuNP size and shape for efficacy in vitro, prior to testing in in vivo models of a disease, has been largely limited to two dimensional monolayers of cells. Two dimensional cell cultures are unable to reproduce conditions experienced by AuNP in the body. In this article, we systematically investigate the effect of different properties of AuNP on the penetration depth into 3D cell spheroids using two-photon microscopy. The 3D spheroids are formed from the HCT116 cell line, a colorectal carcinoma cell line. In addition to studying different sizes and shapes of AuNPs, we also study the effect of an oligo surface chemistry. There is a significant difference between AuNP uptake profiles in the 2D monolayers of cells as compared to the 3D cell spheroids. Additionally, the range of sizes and shapes studied here also exhibit marked differences in uptake penetration depth and efficacy. Finally, our results demonstrate that two-photon microscopy enables quantitative AuNP localization and concentration data to be obtained at the single spheroid level without fluorescent labeling of the AuNP, thus, providing a viable technique for large scale screening of AuNP properties in 3D cell spheroids as compared to tedious and time consuming techniques like electron microscopy.

Weight and volume variation in truckloads of logs hauled in the central Appalachians

Treesearch

Floyd G. Timson

1974-01-01

Variation in volume and weight was found among loaded log trucks even when such factors as truck type, logging job, and driver influence were eliminated. A load range of 10,000 pounds or 1,000 board feet was commonplace for the same truck, driver, and cutting site. Differences in log size, shape, weight, and species caused a major share of this variation. Yet,...

Asteroid 5535 Annefrank size, shape, and orientation: Stardust first results

NASA Technical Reports Server (NTRS)

Duxbury, T. C.; Newburn, R. L., Jr.; Acton, C. H.; Carranza, E.; McElrath, T. P.; Ryan, R. E.; Synnott, S. P.; You, T. H.; Brownlee, D. E.; Cheuvront, A. R.;

Bioavailability of Lead in Small Arms Range Soils

DTIC Science & Technology

2009-08-01

titanium TOC total organic carbon USEPA U.S. Environmental Protection Agency XRF X-ray fluorescence Zn zinc Zr zirconium 1 1.0 EXECUTIVE...particles of inert matrix such as rock or slag of variable size, shape, and association; these chemical and physical properties may influence the absorption...zirconium, Pb=lead, Cu=copper, Mn=manganese, Si=silicon, Zn= zinc , As=arsenic, Cd=cadmium, CEC= cation exchange capacity, TOC = total organic carbon, Sb

The evolution of the platyrrhine talus: A comparative analysis of the phenetic affinities of the Miocene platyrrhines with their modern relatives.

PubMed

Püschel, Thomas A; Gladman, Justin T; Bobe, René; Sellers, William I

2017-10-01

Platyrrhines are a diverse group of primates that presently occupy a broad range of tropical-equatorial environments in the Americas. However, most of the fossil platyrrhine species of the early Miocene have been found at middle and high latitudes. Although the fossil record of New World monkeys has improved considerably over the past several years, it is still difficult to trace the origin of major modern clades. One of the most commonly preserved anatomical structures of early platyrrhines is the talus. This work provides an analysis of the phenetic affinities of extant platyrrhine tali and their Miocene counterparts through geometric morphometrics and a series of phylogenetic comparative analyses. Geometric morphometrics was used to quantify talar shape affinities, while locomotor mode percentages (LMPs) were used to test if talar shape is associated with locomotion. Comparative analyses were used to test if there was convergence in talar morphology, as well as different models that could explain the evolution of talar shape and size in platyrrhines. Body mass predictions for the fossil sample were also computed using the available articular surfaces. The results showed that most analyzed fossils exhibit a generalized morphology that is similar to some 'generalist' modern species. It was found that talar shape covaries with LMPs, thus allowing the inference of locomotion from talar morphology. The results further suggest that talar shape diversification can be explained by invoking a model of shifts in adaptive peak to three optima representing a phylogenetic hypothesis in which each platyrrhine family occupied a separate adaptive peak. The analyses indicate that platyrrhine talar centroid size diversification was characterized by an early differentiation related to a multidimensional niche model. Finally, the ancestral platyrrhine condition was reconstructed as a medium-sized, generalized, arboreal, quadruped. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Morphology of blazar-induced gamma ray halos due to a helical intergalactic magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Andrew J.; Vachaspati, Tanmay, E-mail: andrewjlong@asu.edu, E-mail: tvachasp@asu.edu

We study the characteristic size and shape of idealized blazar-induced cascade halos in the 1–100,GeV energy range assuming various non-helical and helical configurations for the intergalactic magnetic field (IGMF). While the magnetic field creates an extended halo, the helicity provides the halo with a twist. Under simplifying assumptions, we assess the parameter regimes for which it is possible to measure the size and shape of the halo from a single source and then to deduce properties of the IGMF. We find that blazar halo measurements with an experiment similar to Fermi-LAT are best suited to probe a helical magnetic fieldmore » with strength and coherence length today in the ranges 10{sup −17} ∼< B{sub 0} / Gauss ∼< 10{sup −13} and 10 Mpc ∼< λ ∼< 10 Gpc where H ∼ B{sub 0}{sup 2} / λ is the magnetic helicity density. Stronger magnetic fields or smaller coherence scales can still potentially be investigated, but the connection between the halo morphology and the magnetic field properties is more involved. Weaker magnetic fields or longer coherence scales require high photon statistics or superior angular resolution.« less

Nano and micro U1-xThxO2 solid solutions: From powders to pellets

NASA Astrophysics Data System (ADS)

Balice, Luca; Bouëxière, Daniel; Cologna, Marco; Cambriani, Andrea; Vigier, Jean-François; De Bona, Emanuele; Sorarù, Gian Domenico; Kübel, Christian; Walter, Olaf; Popa, Karin

2018-01-01

Nuclear fuels production, structural materials, separation techniques, and waste management, all may benefit from an extensive knowledge in the nano-nuclear technology. In this line, we present here the production of U1-xThxO2 (x = 0 to 1) mixed oxides nanocrystals (NC's) through the hydrothermal decomposition of the oxalates in hot compressed water at 250 °C. Particles of spherical shape and size of about 5.5-6 nm are obtained during the hydrothermal decomposition process. The powdery nanocrystalline products were consolidated by spark plasma sintering into homogeneous mixed oxides pellets with grain sizes in the 0.4 to 5.5 μm range. Grain growth and mechanical properties were studied as a function of composition and size. No grain size effect was observed on the hardness or elastic modulus.

The Shapes of Splash-Form Tektites: Their Geometrical Analysis, Classification and Mechanics of Formation

NASA Astrophysics Data System (ADS)

Stauffer, Mel R.; Butler, Samuel L.

2010-12-01

Splash-form tektites are found with a wide range of sizes and in an intriguing array of shapes ranging from spheres to flat discs to dumbbells. Despite the considerable interest that exists in tektites, there has been relatively little effort to develop rational shape descriptors and to understand the origin of their shapes based on basic physics. Tektites represent a natural laboratory experiment that can be analyzed to better understand the physics of rotating fluid drops. In this paper, we propose a classification scheme based on the axial ratios of ellipsoids, and we analyze the frequency of tektite shapes using a database of over 1,000 measured tektites. We show that the shape distribution for tektites from Thailand and Vietnam are very similar and that the most common tektites are moderately deformed discs but there exist also a significant number of moderately deformed dumbbells, and we argue that this distribution comes about because fluid drops first deform as oblate forms and then undergo a non-axisymmetric instability to become prolate. We also find that the largest tektites are most likely to be weakly deformed oblate objects while the most strongly deformed and most highly prolate forms are considerably smaller. A numerical model for the evolution of an axisymmetric fluid drop, such as a tektite in its molten early stage, is presented which demonstrates that drops that deform relatively slowly over a longer period of time are likely to develop central thinning while those that deform more rapidly are more likely to retain the shape of an ellipsoid. For the numerical parameters used the characteristic time scale for deformation was less than 1 s.

Morpho morphometrics: Shared ancestry and selection drive the evolution of wing size and shape in Morpho butterflies.

PubMed

Chazot, Nicolas; Panara, Stephen; Zilbermann, Nicolas; Blandin, Patrick; Le Poul, Yann; Cornette, Raphaël; Elias, Marianne; Debat, Vincent

2016-01-01

Butterfly wings harbor highly diverse phenotypes and are involved in many functions. Wing size and shape result from interactions between adaptive processes, phylogenetic history, and developmental constraints, which are complex to disentangle. Here, we focus on the genus Morpho (Nymphalidae: Satyrinae, 30 species), which presents a high diversity of sizes, shapes, and color patterns. First, we generate a comprehensive molecular phylogeny of these 30 species. Next, using 911 collection specimens, we quantify the variation of wing size and shape across species, to assess the importance of shared ancestry, microhabitat use, and sexual selection in the evolution of the wings. While accounting for phylogenetic and allometric effects, we detect a significant difference in wing shape but not size among microhabitats. Fore and hindwings covary at the individual and species levels, and the covariation differs among microhabitats. However, the microhabitat structure in covariation disappears when phylogenetic relationships are taken into account. Our results demonstrate that microhabitat has driven wing shape evolution, although it has not strongly affected forewing and hindwing integration. We also found that sexual dimorphism of forewing shape and color pattern are coupled, suggesting a common selective force. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Fourier analysis of human soft tissue facial shape: sex differences in normal adults.

PubMed Central

Ferrario, V F; Sforza, C; Schmitz, J H; Miani, A; Taroni, G

1995-01-01

Sexual dimorphism in human facial form involves both size and shape variations of the soft tissue structures. These variations are conventionally appreciated using linear and angular measurements, as well as ratios, taken from photographs or radiographs. Unfortunately this metric approach provides adequate quantitative information about size only, eluding the problems of shape definition. Mathematical methods such as the Fourier series allow a correct quantitative analysis of shape and of its changes. A method for the reconstruction of outlines starting from selected landmarks and for their Fourier analysis has been developed, and applied to analyse sex differences in shape of the soft tissue facial contour in a group of healthy young adults. When standardised for size, no sex differences were found between both cosine and sine coefficients of the Fourier series expansion. This shape similarity was largely overwhelmed by the very evident size differences and it could be measured only using the proper mathematical methods. PMID:8586558

Predicting Visibility of Aircraft

PubMed Central

Watson, Andrew; Ramirez, Cesar V.; Salud, Ellen

2009-01-01

Visual detection of aircraft by human observers is an important element of aviation safety. To assess and ensure safety, it would be useful to be able to be able to predict the visibility, to a human observer, of an aircraft of specified size, shape, distance, and coloration. Examples include assuring safe separation among aircraft and between aircraft and unmanned vehicles, design of airport control towers, and efforts to enhance or suppress the visibility of military and rescue vehicles. We have recently developed a simple metric of pattern visibility, the Spatial Standard Observer (SSO). In this report we examine whether the SSO can predict visibility of simulated aircraft images. We constructed a set of aircraft images from three-dimensional computer graphic models, and measured the luminance contrast threshold for each image from three human observers. The data were well predicted by the SSO. Finally, we show how to use the SSO to predict visibility range for aircraft of arbitrary size, shape, distance, and coloration. PMID:19462007

Human induced rotation and reorganization of the brain of domestic dogs.

PubMed

Roberts, Taryn; McGreevy, Paul; Valenzuela, Michael

2010-07-26

Domestic dogs exhibit an extraordinary degree of morphological diversity. Such breed-to-breed variability applies equally to the canine skull, however little is known about whether this translates to systematic differences in cerebral organization. By looking at the paramedian sagittal magnetic resonance image slice of canine brains across a range of animals with different skull shapes (N = 13), we found that the relative reduction in skull length compared to width (measured by Cephalic Index) was significantly correlated to a progressive ventral pitching of the primary longitudinal brain axis (r = 0.83), as well as with a ventral shift in the position of the olfactory lobe (r = 0.81). Furthermore, these findings were independent of estimated brain size or body weight. Since brachycephaly has arisen from generations of highly selective breeding, this study suggests that the remarkable diversity in domesticated dogs' body shape and size appears to also have led to human-induced adaptations in the organization of the canine brain.

Optimizing granules size distribution for aerobic granular sludge stability: Effect of a novel funnel-shaped internals on hydraulic shear stress.

PubMed

Zhou, Jia-Heng; Zhang, Zhi-Ming; Zhao, Hang; Yu, Hai-Tian; Alvarez, Pedro J J; Xu, Xiang-Yang; Zhu, Liang

2016-09-01

A novel funnel-shaped internals was proposed to enhance the stability and pollutant removal performance of an aerobic granular process by optimizing granule size distribution. Results showed up to 68.3±1.4% of granules in novel reactor (R1) were situated in optimal size range (700-1900μm) compared to less than 29.7±1.1% in conventional reactor (R2), and overgrowth of large granules was effectively suppressed without requiring additional energy. Consequently, higher total nitrogen (TN) removal (81.6±2.1%) achieved in R1 than in R2 (48.1±2.7%). Hydraulic analysis revealed the existence of selectively assigning hydraulic pressure in R1. The total shear rate (τtotal) on large granules was 3.07±0.14 times higher than that of R2, while τtotal of small granules in R1 was 70.7±4.6% in R2. Furthermore, large granules in R1 with intact extracellular polymeric substances (EPS) outer layer structure entrapped hydroxyapatite at center, which formed a core structure and further enhanced the stability of aerobic granules. Copyright © 2016 Elsevier Ltd. All rights reserved.

Attrition in the kimberlite system

NASA Astrophysics Data System (ADS)

Jones, Thomas J.; Russell, James K.

2018-05-01

The sustained transportation of particles in a suspension commonly results in particle attrition leading to grain size reduction and shape modification. Particle attrition is a well-studied phenomenon that has mainly focussed on sediments produced in aeolian or fluvial environments. Here, we present analogue experiments designed to explore processes of attrition in the kimberlite system; we focus on olivine as it is the most abundant constituent of kimberlite. The attrition experiments on olivine use separate experimental set-ups to approximate two natural environments relevant to kimberlites. Tumbling mill experiments feature a low energy system supporting near continual particle-particle contact and are relevant to re-sedimentation and dispersal processes. Experiments performed in a fluidized particle bed constitute a substantially higher energy environment pertinent to kimberlite ascent and eruption. The run-products of each experiment are analysed for grain size reduction and shape modification and these data are used to elucidate the rates and extents of olivine attrition as a function of time and energy. Lastly, we model the two experimental datasets with an empirical rate equation that describes the production of daughter products (fines) with time. Both datasets approach a fines production limit, or plateau, at long particle residence times; the fluidized system is much more efficient producing a substantially higher fines content and reaches the plateau faster. Our experimental results and models provide a way to forensically examine a wide range of processes relevant to kimberlite on the basis of olivine size and shape properties.

Sample size and classification error for Bayesian change-point models with unlabelled sub-groups and incomplete follow-up.

PubMed

White, Simon R; Muniz-Terrera, Graciela; Matthews, Fiona E

2018-05-01

Many medical (and ecological) processes involve the change of shape, whereby one trajectory changes into another trajectory at a specific time point. There has been little investigation into the study design needed to investigate these models. We consider the class of fixed effect change-point models with an underlying shape comprised two joined linear segments, also known as broken-stick models. We extend this model to include two sub-groups with different trajectories at the change-point, a change and no change class, and also include a missingness model to account for individuals with incomplete follow-up. Through a simulation study, we consider the relationship of sample size to the estimates of the underlying shape, the existence of a change-point, and the classification-error of sub-group labels. We use a Bayesian framework to account for the missing labels, and the analysis of each simulation is performed using standard Markov chain Monte Carlo techniques. Our simulation study is inspired by cognitive decline as measured by the Mini-Mental State Examination, where our extended model is appropriate due to the commonly observed mixture of individuals within studies who do or do not exhibit accelerated decline. We find that even for studies of modest size ( n = 500, with 50 individuals observed past the change-point) in the fixed effect setting, a change-point can be detected and reliably estimated across a range of observation-errors.

Identification of major and minor QTL for ecologically important morphological traits in three-spined sticklebacks (Gasterosteus aculeatus).

PubMed

Liu, Jun; Shikano, Takahito; Leinonen, Tuomas; Cano, José Manuel; Li, Meng-Hua; Merilä, Juha

2014-04-16

Quantitative trait locus (QTL) mapping studies of Pacific three-spined sticklebacks (Gasterosteus aculeatus) have uncovered several genomic regions controlling variability in different morphological traits, but QTL studies of Atlantic sticklebacks are lacking. We mapped QTL for 40 morphological traits, including body size, body shape, and body armor, in a F2 full-sib cross between northern European marine and freshwater three-spined sticklebacks. A total of 52 significant QTL were identified at the 5% genome-wide level. One major QTL explaining 74.4% of the total variance in lateral plate number was detected on LG4, whereas several major QTL for centroid size (a proxy for body size), and the lengths of two dorsal spines, pelvic spine, and pelvic girdle were mapped on LG21 with the explained variance ranging from 27.9% to 57.6%. Major QTL for landmark coordinates defining body shape variation also were identified on LG21, with each explaining ≥15% of variance in body shape. Multiple QTL for different traits mapped on LG21 overlapped each other, implying pleiotropy and/or tight linkage. Thus, apart from providing confirmatory data to support conclusions born out of earlier QTL studies of Pacific sticklebacks, this study also describes several novel QTL of both major and smaller effect for ecologically important traits. The finding that many major QTL mapped on LG21 suggests that this linkage group might be a hotspot for genetic determinants of ecologically important morphological traits in three-spined sticklebacks.

[Eyeball shape in children with emmetropia and myopia].

PubMed

Dolzhich, G I; Shurygina, I P; Shapovalova, V M

1991-01-01

In order to determine the eyeball shape, the authors have carried out ultrasonic biometry of its three major parameters, the anteroposterior axis (APA), horizontal diameter (HD), and vertical diameter (VD), and estimated the ratios of these values (APA/HD and APA/VD) in children with emmetropia (234 eyes) and those with slight and medium-grave myopia (660 eyes), aged 7 to 14. The findings evidence a compressed ellipsoidal shape of the eyeball, presenting as a vertical oval, in all subjects with emmetropic refraction, whatever their age. In myopia the eyeball shape transforms, and all the eyeball sizes are increased, but the APA size is growing more rapidly than the rest sizes, and the eyeball acquires the ball shape with a trend to an elongated ellipsoidal shape. The mean APA length in 7-14-year-old children with emmetropia was up to 23 +/- 0.15 mm, whereas in those with the ball shape of the eyeball it was distended.

Laser light scattering review

NASA Technical Reports Server (NTRS)

Schaetzel, Klaus

1989-01-01

Since the development of laser light sources and fast digital electronics for signal processing, the classical discipline of light scattering on liquid systems experienced a strong revival plus an enormous expansion, mainly due to new dynamic light scattering techniques. While a large number of liquid systems can be investigated, ranging from pure liquids to multicomponent microemulsions, this review is largely restricted to applications on Brownian particles, typically in the submicron range. Static light scattering, the careful recording of the angular dependence of scattered light, is a valuable tool for the analysis of particle size and shape, or of their spatial ordering due to mutual interactions. Dynamic techniques, most notably photon correlation spectroscopy, give direct access to particle motion. This may be Brownian motion, which allows the determination of particle size, or some collective motion, e.g., electrophoresis, which yields particle mobility data. Suitable optical systems as well as the necessary data processing schemes are presented in some detail. Special attention is devoted to topics of current interest, like correlation over very large lag time ranges or multiple scattering.

L1(0)-FePd nanocluster wires by template-directed thermal decomposition and subsequent hydrogen reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, BZ; Marinescu, M; Liu, JF

2013-12-14

This paper reports the nanostructure, formation mechanism, and magnetic properties of tetragonal L1(0)-type Fe55Pd45 (at. %) nanocluster wires (NCWs) fabricated by thermal decomposition of metal nitrates and subsequent hydrogen reduction in nanoporous anodized aluminum oxide templates. The as-synthesized NCWs have diameters in the range of 80-300 nm, and lengths in the range of 0.5-10 mu m. The NCWs are composed of roughly round-shaped nanoclusters in the range of 3-30 nm in size and a weighted average size of 10 nm with a mixture of single-crystal and poly-crystalline structures. The obtained intrinsic coercivity H-i(c) of 3.32 kOe at room temperature formore » the tetragonal Fe55Pd45 NCWs is higher than those of electrodeposited Fe-Pd solid nanowires while among the highest values reported so far for L1(0)-type FePd nanoparticles. (C) 2013 AIP Publishing LLC.« less

Human Facial Shape and Size Heritability and Genetic Correlations.

PubMed

Cole, Joanne B; Manyama, Mange; Larson, Jacinda R; Liberton, Denise K; Ferrara, Tracey M; Riccardi, Sheri L; Li, Mao; Mio, Washington; Klein, Ophir D; Santorico, Stephanie A; Hallgrímsson, Benedikt; Spritz, Richard A

2017-02-01

The human face is an array of variable physical features that together make each of us unique and distinguishable. Striking familial facial similarities underscore a genetic component, but little is known of the genes that underlie facial shape differences. Numerous studies have estimated facial shape heritability using various methods. Here, we used advanced three-dimensional imaging technology and quantitative human genetics analysis to estimate narrow-sense heritability, heritability explained by common genetic variation, and pairwise genetic correlations of 38 measures of facial shape and size in normal African Bantu children from Tanzania. Specifically, we fit a linear mixed model of genetic relatedness between close and distant relatives to jointly estimate variance components that correspond to heritability explained by genome-wide common genetic variation and variance explained by uncaptured genetic variation, the sum representing total narrow-sense heritability. Our significant estimates for narrow-sense heritability of specific facial traits range from 28 to 67%, with horizontal measures being slightly more heritable than vertical or depth measures. Furthermore, for over half of facial traits, >90% of narrow-sense heritability can be explained by common genetic variation. We also find high absolute genetic correlation between most traits, indicating large overlap in underlying genetic loci. Not surprisingly, traits measured in the same physical orientation (i.e., both horizontal or both vertical) have high positive genetic correlations, whereas traits in opposite orientations have high negative correlations. The complex genetic architecture of facial shape informs our understanding of the intricate relationships among different facial features as well as overall facial development. Copyright © 2017 by the Genetics Society of America.

Screening of cyanobacterial extracts for synthesis of silver nanoparticles.

PubMed

Husain, Shaheen; Sardar, Meryam; Fatma, Tasneem

2015-08-01

Improvement of reliable and eco-friendly process for synthesis of metallic nanoparticles is a significant step in the field of application nanotechnology. One approach that shows vast potential is based on the biosynthesis of nanoparticles using micro-organisms. In this study, biosynthesis of silver nanoparticles (AgNP) using 30 cyanobacteria were investigated. Cyanobacterial aqueous extracts were subjected to AgNP synthesis at 30 °C. Scanning of these aqueous extracts containing AgNP in UV-Visible range showed single peak. The λ max for different extracts varied and ranged between 440 and 490 nm that correspond to the "plasmon absorbance" of AgNP. Micrographs from scanning electron microscope of AgNP from cyanobacterial extracts showed that though synthesis of nanoparticles occurred in all strains but their reaction time, shape and size varied. Majority of the nanoparticles were spherical. Time taken for induction of nanoparticles synthesis by cyanobacterial extracts ranged from 30 to 360 h and their size from 38 to 88 nm. In terms of size Cylindrospermum stagnale NCCU-104 was the best organism with 38 and 40 nm. But in terms of time Microcheate sp. NCCU-342 was the best organism as it took 30 h for AgNP synthesis.

Surface and finite size effect on fluctuations dynamics in nanoparticles with long-range order

NASA Astrophysics Data System (ADS)

Morozovska, A. N.; Eliseev, E. A.

2010-02-01

The influence of surface and finite size on the dynamics of the order parameter fluctuations and critical phenomena in the three-dimensional (3D)-confined systems with long-range order was not considered theoretically. In this paper, we study the influence of surface and finite size on the dynamics of the order parameter fluctuations in the particles of arbitrary shape. We consider concrete examples of the spherical and cylindrical ferroic nanoparticles within Landau-Ginzburg-Devonshire phenomenological approach. Allowing for the strong surface energy contribution in micro and nanoparticles, the analytical expressions derived for the Ornstein-Zernike correlator of the long-range order parameter spatial-temporal fluctuations, dynamic generalized susceptibility, relaxation times, and correlation radii discrete spectra are different from those known for bulk systems. Obtained analytical expressions for the correlation function of the order parameter spatial-temporal fluctuations in micro and nanosized systems can be useful for the quantitative analysis of the dynamical structural factors determined from magnetic resonance diffraction and scattering spectra. Besides the practical importance of the correlation function for the analysis of the experimental data, derived expressions for the fluctuations strength determine the fundamental limits of phenomenological theories applicability for 3D-confined systems.

Regular oscillations and random motion of glass microspheres levitated by a single optical beam in air

DOE PAGES

Moore, Jeremy; Martin, Leopoldo L.; Maayani, Shai; ...

2016-02-03

We experimentally reporton optical binding of many glass particles in air that levitate in a single optical beam. A diversity of particle sizes and shapes interact at long range in a single Gaussian beam. Our system dynamics span from oscillatory to random and dimensionality ranges from 1 to 3D. In conclusion, the low loss for the center of mass motion of the beads could allow this system to serve as a standard many body testbed, similar to what is done today with atoms, but at the mesoscopic scale.

The effect of finite geometry on the three-dimensional transfer of solar irradiance in clouds

NASA Technical Reports Server (NTRS)

Davies, R.

1978-01-01

Results are presented for a Monte Carlo model applied to a wide range of cloud widths and heights, and for an analytical model restricted in its application to cuboidally shaped clouds whose length, breadth, and depth may be varied independently; the clouds must be internally homogeneous with respect to their intrinsic radiative properties. Comparative results from the Monte Carlo method and the derived analytical model are presented for a wide range of cloud sizes, with special emphasis on the effects of varying the single scatter albedo, the solar zenith angle, and the scattering phase angle.

Engineering cartilage substitute with a specific size and shape using porous high-density polyethylene (HDPE) as internal support.

PubMed

Wu, Yujia; Zhu, Lie; Jiang, Hua; Liu, Wei; Liu, Yu; Cao, Yilin; Zhou, Guangdong

2010-04-01

Despite the great advances in cartilage engineering, constructing cartilage of large sizes and appropriate shapes remains a great challenge, owing to limits in thickness of regenerated cartilage and to inferior mechanical properties of scaffolds. This study introduces a pre-shaped polyglycolic acid (PGA)-coated porous high-density polyethylene (HDPE) scaffold to overcome these challenges. HDPE was carved into cylindrical rods and wrapped around by PGA fibres to form PGA-HDPE scaffolds. Porcine chondrocytes were seeded into the scaffolds and the constructs were cultured in vitro for 2 weeks before subcutaneous implantation into nude mice. Scaffolds made purely of PGA with the same size and shape were used as a control. After 8 weeks of implantation, the construct formed cartilage-like tissue and retained its pre-designed shape and size. In addition, the regenerated cartilage grew and completely surrounded the HDPE core, which made the entire cartilage substitute biocompatible to its implanted environment as native cartilage similarly does. By contrast, the shape and size of the constructs in the control group seriously deformed and obvious hollow cavity and necrotic tissue were observed in the inner region. These results demonstrate that the use of HDPE as the internal support of a biodegradable scaffold has the potential to circumvent the problems of limitations in size and shape, with promising implications for the development of engineered cartilage appropriate for clinical applications. Copyright 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Preparation of α-alumina nanoparticles with various shapes via hydrothermal phase transformation under supercritical water conditions

NASA Astrophysics Data System (ADS)

Hakuta, Y.; Nagai, N.; Suzuki, Y.-H.; Kodaira, T.; Bando, K. K.; Takashima, H.; Mizukami, F.

2013-12-01

Alumina (Al2O3) fine particles are widely used as industrial materials including fillers for metal or plastics, paints, polisher, cosmetics and electric substrates, due to its high hardness, chemical stability, and high thermal conductivity. The performance of those industrial products is closely related to the particle size or shape of the alumina particles used, and thus a new synthetic method to control size, shape, and crystal structure of the aluminum oxide is desired for the improvement of the performance. Hydrothermal phase transformation using various aluminum compounds such as oxide, hydroxide, and salt as a staring material, is known as one of the synthetic methods for producing alumina fine particles; however, the influence about the size and shape of the starting aluminum compounds has been little mentioned, although they strongly affect the size and shape of the final products. In this study, we investigated the influence of the shape, size and crystal structure of the starting aluminum compounds on those of the products, and newly succeeded in the production of rod-like α-Al2O3 nanoparticles from fibrous boehmite nanoparticles using hydrothermal phase transformation under supercritical water conditions.

Theoretical analysis of the effect of particle size and support on the kinetics of oxygen reduction reaction on platinum nanoparticles

NASA Astrophysics Data System (ADS)

Viswanathan, Venkatasubramanian; Wang, Frank Yi-Fei

2012-07-01

We perform a first-principles based computational analysis of the effect of particle size and support material on the electrocatalytic activity of platinum nanoparticles. Using a mechanism for oxygen reduction that accounts for electric field effects and stabilization from the water layer on the (111) and (100) facets, we show that the model used agrees well with linear sweep voltammetry and rotating ring disk electrode experiments. We find that the per-site activity of the nanoparticle saturates for particles larger than 5 nm and we show that the optimal particle size is in the range of 2.5-3.5 nm, which agrees well with recent experimental work. We examine the effect of support material and show that the perimeter sites on the metal-support interface are important in determining the overall activity of the nanoparticles. We also develop simple geometric estimates for the activity which can be used for determining the activity of other particle shapes and sizes.We perform a first-principles based computational analysis of the effect of particle size and support material on the electrocatalytic activity of platinum nanoparticles. Using a mechanism for oxygen reduction that accounts for electric field effects and stabilization from the water layer on the (111) and (100) facets, we show that the model used agrees well with linear sweep voltammetry and rotating ring disk electrode experiments. We find that the per-site activity of the nanoparticle saturates for particles larger than 5 nm and we show that the optimal particle size is in the range of 2.5-3.5 nm, which agrees well with recent experimental work. We examine the effect of support material and show that the perimeter sites on the metal-support interface are important in determining the overall activity of the nanoparticles. We also develop simple geometric estimates for the activity which can be used for determining the activity of other particle shapes and sizes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30572k

The effects of colorimetric detection of heavy metal ions based on Au nanoparticles (NPs): size and shape—a case of Co2+

NASA Astrophysics Data System (ADS)

Leng, Yumin; He, Junbao; Li, Bo; Xing, Xiaojing; Guo, Yongming; Ye, Liqun; Lu, Zhiwen

2017-09-01

The different sized and shaped Au NPs have intrigued considerable attention, because they possess different surface plasma resonance (SPR) absorption bands and thus result in many colorimetric Au NP-based detection applications. In this article, four different sized and shaped Au NPs of nanodots/rods were prepared and characterized. The as-prepared Au NPs were modified by the negatively charged anions of [SCH2CO2]2- to investigate both the size and shape effects of modified Au NPs on colorimetric detection of Co2+ and the corresponding SPR absorption properties. The different-shaped Au NPs possess different SPR absorption properties. The Au nanorods appeared to be colorimetric sensitive for Co2+ sensing.

Towards a perceptive understanding of size in cellular biology.

PubMed

Zoppè, Monica

2017-06-29

Cells are minute-typically too small to be seen by the human eye. Even so, the cellular world encompasses a range of scales, from roughly a tenth of a nanometer (10 -10 m) to a millimeter (10 -3 m) or larger, spanning seven orders of magnitude or more. Because they are so far from our experience, it is difficult for us to envision such scales. To help our imagination grasp such dimensions, I propose the adoption of a 'perceptive scale' that can facilitate a more direct experience of cellular sizes. From this, as I argue below, will stem a new perception also of biological shape, cellular space and dynamic processes.

Optical Properties of a Semimagnetic Quantum Well in a Proximity of a Superconducting Film

NASA Astrophysics Data System (ADS)

Lebecki, K. M.; Kłopotowski, Ł.; Kossut, J.

2006-11-01

We consider, via numerical calculations, a hybrid structure made of a semimagnetic Cd1-xMnxTe quantum well deposited in a close proximity to superconducting niobium film. We simulate photoluminescence and the Faraday rotation spectra, modified by the presence of vortices in this type II superconductor. The magnitude of the evaluated effects is small - the vortex induced spectral line shape variation is of the order of 1% at 1 K and 0.1% at 3 K and is expected to occur mainly in the field range between 0.03 T and 0.05 T.