Size-dependent Analysis Research Articles

Publisher's Note: “Analysis of Size Dependence of Quality Factor of Quartz-Crystal Tuning Fork”

Publisher's Note: “Analysis of Size Dependence of Quality Factor of Quartz-Crystal Tuning Fork”

Analysis of Size Dependence of Quality Factor of Quartz-Crystal Tuning Fork

We derived an approximate formula for the quality factor (Q value or Q) of a quartz-crystal tuning fork by applying the approximate calculation method developed by Landau et al. and Lifshitz et al. to the thermoelastic coupling equations previously obtained from the viewpoint of the thermoelasticity for a cantilever beam. We found that our calculated Q obtained using the approximate formula is half of the measured Q for an etching-processed quartz-crystal tuning fork. Furthermore, we derived the equation of the size dependence of Q by further approximating the approximate formula for Q at a constant frequency and various frequencies. The predicted size dependence of Q from these obtained equations is confirmed by measuring the Q of seven commercially available quartz-crystal tuning forks. The equations, which show the size dependence of Q, and the approximate formula for Q obtained here are effective for explaining the decreases in Q of the miniaturized quartz-crystal tuning fork.

Analysis of Size Dependence of Quality Factor of Quartz-Crystal Tuning Fork

Analysis of Size Dependence of Quality Factor of Quartz-Crystal Tuning Fork

Intraobserver and interobserver agreement of volume perfusion CT (VPCT) measurements in patients with lung lesions

ObjectivesTo evaluate intraobserver and interobserver agreement of manually encompassed lung lesions for perfusion measurements using volume-perfusion computed tomography (VPCT). Materials and methodsInstitutional review board approval and informed consent were obtained. HIPAA guidelines were followed. A 65-s dynamic study was acquired with scan parameters 80kV, 60mAs (80mAs for patients ≥70kg), 128×0.6mm collimation. Blood flow (BF), blood volume (BV) and Ktrans parameters were determined by syngo volume perfusion CT body with 88 lesions analyzed retrospectively. ResultsWithin-subject coefficients of variation for intraobserver agreement (range 6.59–12.82%) were superior to those for interobserver agreement (range 21.75–38.30%). Size-dependent analysis revealed lower agreements for lesions <4cm as compared to larger lesions. Additionally, agreements of the upper, middle and lower lung zones were different. ConclusionsIntraobserver agreement was substantial for VPCT lung cancer perfusion measurements encouraging the use for tumor characterization and therapy response monitoring. Interobserver agreement is limited and unexperienced readers should be trained before using this new method.

Size dependent stability analysis of circular ultrathin films in elastic medium with consideration of surface energies

In this article, analytical framework is developed for size dependent symmetric stability and self-instability of circular nanoplates including surface effects using modified Kirchhoff plate theory. The surrounding elastic medium is modeled as Winkler elastic foundation and its effect is comprehensively studied on self-instability problems. The derived explicit solutions contain Bessel functions with modified arguments reflecting the size dependency of the buckling loads. In order to check the results an inverse formulation is presented for effective Young's modulus using the buckling loads to be verified by previous experimental results for nanowires. Several numerical examples are given for two types of materials with positive and negative surface properties to show the general trends of size dependencies. Some problems and limitations are explored for consistency of results with experiments and suggestions for future works.

Parasitic resistance analysis of pseudovertical structure diamond Schottky barrier diode

AbstractDiamond Schottky barrier diodes (SBDs) in pseudovertical configuration were fabricated and analysed. Temperature and diode size dependence analysis of forward I–V characteristics showed an increase in current with increasing diode size, and temperature, along with a decrease in device series‐resistance (RS). It was revealed that device RS consisted of two major factors: primarily significant resistance arising from p+ layer [$R_{({\rm p}^{ + } )} $], and the other from p− layer [$R_{({\rm p}^{ - } )} $]. High temperature characteristics of SBDs in varying size exhibited a saturating limitation in the increase of forward current with increasing diode size, because the decrease in device series resistance (RS) is mainly by $R_{({\rm p}^{ - } )} $ part, whereas $R_{({\rm p}^{ + } )} $ is same irrespective of diode size, and forms to be parasitic resistance of device structure. Curve fitting analysis of experimental RS with our proposed model for $R_{({\rm p}^{ + } )} $ of varying p+ layer thickness revealed that, parasitic resistance originating from p+ layer can be decreased by increasing its thickness, towards achieving high current transport.

Size dependent dynamic analysis of nanoplates

Determination of accurate behavior of nanostructures is important in nanoelectromechanical systems in view of the shortcoming of classical theories of mechanics. In this study size-dependent transverse vibration of nanoplates is investigated. Surface properties which include surface elasticity and residual stresses are taken into account. Elasticity modulus of the bulk part is considered dependent on size as well as temperature. Kirchhoff theory of laminated plates is used to derive the governing differential equation of nanoplate structure.

Size and density dependent sedimentation analysis of advanced nanoparticle systems

Various functional colloidal systems like polymer grafted inorganic particles, complex multi-component mixtures, organic–inorganic hybrid particles, inorganic–inorganic core–shell particles and swellable particles were characterized by sedimentation coefficient analysis in analytical ultracentrifuge owing to the accurate correlation of the sedimentation coefficient with variations in size and density of the materials. The sedimentation coefficient is absolute in nature and does not require any property information beforehand. By following the changes in the sedimentation coefficient and its distribution, it could be established if the polymer grafting on the surface of the inorganic particles took place or if the organic–inorganic or inorganic–inorganic hybrid was formed or if the particles were strongly crosslinked or swellable. The complex particle mixtures were also quantified for the number of components contained in them and their exact amounts by following the sedimentation coefficient distributions.

Quantifying changes and trends in glacier area and volume in the Austrian Ötztal Alps (1969-1997-2006)

Abstract. In this study we apply a simple and reliable method to derive recent changes in glacier area and volume by taking advantage of high resolution LIDAR (light detection and ranging) DEMs (digital elevation models) from the year 2006. Together with two existing glacier inventories (1969 and 1997) the new dataset enables us to quantify area and volume changes over the past 37 years at three dates. This has been done for 81 glaciers (116 km2) in the Ötztal Alps which accounts for almost one third of Austria's glacier extent. Glacier area and volume have reduced drastically with significant differences within the individual size classes. Between 1997 and 2006 an overall area loss of 10.5 km2 or 8.2% occurred. Volume has reduced by 1.0 km3 which accounts for a mean thickness change of −8.2 m. The availability of three comparable inventories allows a comprehensive size and altitude dependent analysis of glacier changes but lacks a high temporal resolution. For the comparison of rates of changes between the two different periods (1969 to 1997 with 1997 to 2006) we propose two approaches in this study: a) to estimate mean overall rates of changes (including a period of advance) and b) to extract periods of net-retreat by using additional information (length change and mass balance measurements). Analysis of the resulting acceleration factors reveals that the retreat of volume and mean thickness changes has accelerated significantly more than that of area changes.

Application of synchronous fluorescence scan spectroscopy for size dependent simultaneous analysis of CdTe nanocrystals and their mixtures

In this paper, synchronous fluorescence scan (SFS) spectroscopy has been applied for the first time for the simultaneous determination of a mixture of CdTe fluorescent nanocrystals (NCs) of various sizes without a pre-separation step. It is observed that synchronous fluorescence maximum correlates well with the size of the nanocrystals, i.e.; the λ SFS max is useful to determine size dependency of NCs. Synchronous fluorescence maximum along with the second derivative can identify individual NCs in a mixture in water. The method is found to be simple, sensitive, selective and fast for NCs determination in aqueous media.

Optimization of Low-Contrast Detectability in Thin-Collimated Modern Multidetector CT Using an Interactive Sliding-Thin-Slab Averaging Algorithm

To analyze the effects of the sliding-thin-slab averaging algorithm on low-contrast performance in MDCT imaging and to find reasonable parameters for clinical routine work. A low-contrast phantom simulating hypodense lesions (20 HU object contrast) was scanned with a 16-slice spiral CT scanner using different mAs-settings of 25, 50, 100, and 195 mAs. Other scan parameters were as follows: tube voltage = 120 kVp, slice collimation = 0.625 mm, pitch = 1.375 (high speed), reconstruction interval = 0.5 mm. Images were reconstructed with soft, standard, and bone algorithms, resulting in a total of 12 datasets. A sliding-thin-slab averaging algorithm was applied to these primary datasets, systematically varying the slab thickness between 0.5 and 5.0 mm. The low-contrast performance of the resulting datasets was semi-automatically analyzed using a statistical reader-independent approach: A size-dependent analysis of the image noise within the phantom was used to empirically generate a contrast discrimination function (CDF). The ratio between the actual contrast and the minimum contrast necessary for the detection (as given by the CDF) was calculated for all lesions in each dataset and used to evaluate the low-contrast detectability of the different lesions at increasing slab thickness. The results were compared with the original datasets to calculate the improvement in low-contrast detectability. Using the sliding-thin-slab algorithm, low-contrast performance was increased by a factor between 1.1 and 1.7 when compared with the primary dataset. The improvement of the visibility index at optimal slab thickness when compared with the original slice thickness (0.625 mm) was statistically significant (P < 0.05, Student t test) for the following datasets: 8 mm: all datasets; 6 mm: 25 mAs/soft, 195 mAs/bone, 25 mAs/bone; 5 mm: 25 mAs/soft, 25 mAs/bone. The ideal slab thickness over all datasets was 43% (+/-3%) of the diameter of the lesion to be detected. The use of an interactive sliding-thin-slab averaging algorithm can be readily applied to optimize low-contrast detectability in thin-collimated CT datasets. As a general rule for daily routine, a slice thickness of approximately 2.5 to 3.0 mm can be regarded as a reasonable preset, resulting in an optimized detectability of lesions with a diameter of 5 mm and above.

Interaction of CO with PdAu(111) and PdAu(100) Bimetallic Surfaces: A Theoretical Cluster Model Study

Structural parameters, binding energies, and bonding mechanism of CO molecules on PdAu(111) and PdAu(100) surface alloys have been investigated at the density functional level by employing a cluster model approach. Cluster models have been constructed to represent second-neighbor Pd pairs on both the exposed gold surfaces, given that special ensembles are able to confine reactants in a small region of bimetallic catalysts. Analysis of the cluster size dependence of the chemisorption properties has been carried out together with the study of the influence of exchange correlation functional and basis set quality. An accurate description of the bonding mechanism of CO on top of Pd monomers surrounded by gold atoms has been achieved by an atom-projected description of the surface bond. The remarkable agreement of computed results with available experimental information and previous periodic supercell calculations clearly indicates that the adopted cluster models are suitable for chemisorption studies on PdAu surface alloys.

Discrete dislocation plasticity analysis of the grain size dependence of the flow strength of polycrystals

The grain size dependence of the flow strength of polycrystals is analyzed using plane strain, discrete dislocation plasticity. Dislocations are modeled as line singularities in a linear elastic solid and plasticity occurs through the collective motion of large numbers of dislocations. Constitutive rules are used to model lattice resistance to dislocation motion, as well as dislocation nucleation, dislocation annihilation and the interaction with obstacles. The materials analyzed consist of micron scale grains having either one or three slip systems and two types of grain arrangements: either a checker-board pattern or randomly dispersed with a specified volume fraction. Calculations are carried out for materials with either a high density of dislocation sources or a low density of dislocation sources. In all cases, the grain boundaries are taken to be impenetrable to dislocations. A Hall–Petch type relation is predicted with Hall–Petch exponents ranging from ≈0.3 to ≈1.6 depending on the number of slip systems, the grain arrangement, the dislocation source density and the range of grain sizes to which a Hall–Petch expression is fit. The grain size dependence of the flow strength is obtained even when no slip incompatibility exists between grains suggesting that slip blocking/transmission governs the Hall–Petch effect in the simulations.

Asymptotic Analysis of Boundary-Induced Size Dependence of Fracture Properties

The recently-developed boundary effect concept and associated asymptotic model are used to explain the size effect phenomena in fracture of quasi-brittle materials. It is demonstrated that the size dependence of the fracture toughness and strength of quasi-brittle materials is indeed due to the influences of specimen boundaries on the failure mode and therefore, on the strength of the specimen. To verify the boundary effect concept, fracture tests on a high strength concrete reported by Karihaloo et al are analysed and predicted using the asymptotic model. The results show that the predictions of the asymptotic boundary effect model agree very well with those experimental results.

Energy density analysis of cluster size dependence of surface–molecule interactions (II): Formate adsorption onto a Cu(111) surface

Adsorption of formate (HCOO) onto a Cu(111) surface has been treated theoretically using 18 kinds of Cu(n) (6 < or = n < or = 56) clusters. The energy density analysis (EDA) proposed by Nakai has been adopted to examine surface-molecule interactions for different cluster sizes. EDA results for the largest model cluster Cu(56) have shown that the adsorption-induced energy density variation in Cu atoms decays with distance from the adsorption site. Analysis of this decay, which can be carried out using the EDA technique, is important because it enables verification of the reliability of the model cluster used. In the case of formate adsorption onto the Cu(111) surface, it is found that at least a four-layer model cluster is necessary to treat the surface-molecule interaction with chemical accuracy.

Quantification of stochastically stable representative volumes for random heterogeneous materials

This paper details a procedure to determine lower bounds on the size of representative volume elements (RVEs) by which the size of the RVE can be quantified objectively for random heterogeneous materials. Here, attention is focused on granular materials with various distributions of inclusion size and volume fraction of inclusions. An extensive analysis of the RVE size dependence on the various parameters is performed. Both deterministic and stochastic parameters are analysed. Also, the effects of loading mode and the parameter of interest are studied. As the RVE size is a function of the material, some material properties such as Young's modulus and Poisson's ratio are analysed as factors that influence the RVE size. The lower bound of RVE size is found as a function of the stochastically distributed volume fraction of inclusions; thus the stochastic stability of the obtained results is assessed. To this end a newly defined concept of stochastic stability (DH-stability) is introduced by which stochastic effects can be included in the stability considerations. DH-stability can be seen as an extension of classical Lyapunov stability. As is shown, DH-stability provides an objective tool to establish the lower bound nature of RVEs for fluctuations in stochastic parameters.

Enhancement of Dye Fluorescence by Gold Nanoparticles: Analysis of Particle Size Dependence

Rose Bengal was spun on spherical gold nanoparticles immobilized on a quartz plate by a silane coupling agent. The enhancement of the dye fluorescence was studied by changing the diameter of the gold nanoparticles from 20 to 250 nm. A maximum enhancement of dye fluorescence was observed at a size of 100 nm. We found good agreement between the experimental result and the theoretical calculation. From the theoretical analysis it is suggested that the maximum enhancement is obtained when the incident light and fluorescence light are in optimum resonance with the surface plasmons in the gold nanoparticles. These results demonstrate that the control of particle size is extremely important to obtain an optimum enhancement of dye fluorescence caused by metal particles.

Energy density analysis of cluster size dependence of surface-molecule interactions: H2, C2H2, C2H4, and CO adsorption onto Si(100)-(2x1) surface.

Adsorption of H2, C2H2, C2H4, and CO onto a Si(100)-(2x1) surface has been treated theoretically using Si(12n - 3)H(8n + 4) (n = 1-4) clusters. The energy density analysis (EDA) proposed by Nakai has been adopted to examine surface-molecule interactions for different cluster sizes. EDA results for the largest model cluster Si45H36 have shown that the adsorption-induced energy density variation in Si atoms decays with distance from the adsorption site. Analysis of this decay, which can be carried out using the EDA technique, is important because it enables verification of the reliability of the model cluster used. In the cases of H2, C2H2, C2H4, and CO adsorption onto the Si(100)-(2x1) surface, it is found that at least a Si21H20 cluster is necessary to treat the surface-molecule interaction with chemical accuracy.

Pinched inlet split flow thin fractionation for continuous particle fractionation: application to marine sediments for size-dependent analysis of PCDD/Fs and metals.

It is demonstrated that split-flow thin (SPLITT) fractionation, a continuous separation technique for sorting particles or macromolecules, can be utilized for the fractionation of environmental particles to study a size-dependent analysis of pollutants. In this study, focuses are made on the use of a pinched inlet gravitational SPLITT fractionation, a modified form of SPLITT channel formed by reducing the sample inlet thickness of the channel to improve separation efficiency, to separate marine sediments into five different sizes (<1.0, approximately 1.0 to 2.5, approximately 2.5 to 5.0, approximately 5.0 to 10, and approximately 10 to 53 microm). The resulting size fractions are examined with high resolution gas chromatography/high resolution mass spectrometry to determine the size-dependent distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans along with a statistical data treatment and are analyzed with inductively coupled plasma-atomic emission spectrometry and graphite furnace atomic absorption spectrometry to ascertain its major and trace metals. It is shown that the combined analytical methods detailed in this study can be powerfully utilized in such a way as to analyze pollutant distribution and its concentration with regard to particle sizes for an environmental assessment.

Quantitative analysis of the bit size dependence on the pulse width and pulse voltage in ferroelectric memory devices using atomic force microscopy

The Bit formation using atomic force microscopy (AFM) was studied on 270-nm-thick 〈111〉 preferentially oriented Pb(Zr0.4Ti0.6)O3 (PZT) films prepared by the sol-gel process. To minimize the cantilever-sample capacitive force interaction, the experiment was carried out at or near the sample edge. Bit formation was investigated by calculating the electric field in AFM-tip/PZT film/bottom electrode configuration. It was found both experimentally and theoretically that the bit size is linearly dependent on the pulse voltage and the logarithmic value of the pulse width. The linear dependence of the bit size on the logarithmic value of pulse width was explained from the relationship between the switching time and electric field. It was found that the minimum bit size of a fully penetrating domain equals the film thickness.