Cylindrical Form Factor Research Articles

Computational simulation of impact perforation of polymeric-foam core sandwiched composites with different skin–face configurations

The normal and oblique impact perforation responses of composite sandwich panels based on a Rohacell polymeric-foam core are numerically investigated at high impact energies (>60 J). A cylindrical form factor with a diameter of 140 mm and a thickness of 15 mm is selected for the sandwich specimens. Four different stacking sequences of 1 mm carbon/epoxy face sheets are considered (i.e., quasi-isotropic, cross-ply, angle-ply, and unidirectional stacking). A computational model was constructed using LS-DYNA finite element software and an inverse perforation testing scheme adapted with a split Hopkinson bar and confirmed by comparing these results with those obtained using the free shooting projectile-target testing schemes published in the literature. The effects of impact energy, failure modes, impact angles, and damage key parameters are analyzed. The results reveal the contact force versus displacement curves are highly influenced by the impact energy increases. The stacking sequence of the face sheets does not influence the energy absorption capacity. However, the maximum absorbed energy increases with an increasing impact angle up to 20°. Using Hopkinson bars in conjunction with the virtual inverse perforation testing approach is effective for examining the response of sandwich composites at high impact energies.

Quantitative collagen fiber assessment in myopic guinea pig eye sclera using a cylindrical Gaussian form factor at 80 MHz

Myopia (also called near-sightedness) is an irreversible ocular abnormality that occurs when the eye is excessively elongated, resulting in defocused images and vision. When myopia progresses to pathological myopia, the possibility of permanent vision loss is extremely high. Therefore, it is important to identify early myopic eyes likely to progress to pathologic myopia and vision loss to start treatment and intervene as soon as possible. As myopia progresses, posterior eye elongation is caused by changes in the microstructural properties of the sclera including decreased collagen density and fibril diameters. High-frequency quantitative ultrasound (QUS) allows measuring biomechanical parameters associated with changes in tissue microstructure. This study investigated microstructural changes occurring in the posterior sclera in myopic guinea pig eyes using two independent QUS approaches at 80-MHz: envelope statistics quantification using the Homodyned-K distribution and backscatter coefficient quantification using a cylindrical Gaussian form factor. QUS parameters suggest changes in collagen fiber size occur in myopic sclera and is associated with microstructural changes in the scleral collagen fiber homogeneity and density. In conclusion, high-frequency QUS has the potential to quantitatively characterize microstructural changes that occur in the posterior sclera during myopia development and/or progression.

Smaller than MLCC: CCW (Ceramic Capacitor Wire)

The world’s smallest discrete capacitor was invented in a cylindrical form factor for high-frequency power delivery, contrary to a planar capacitor such as MLCC. A dielectric layer of Al2O3 (5~50nm ALD) was deposited on conventional Au metal wires (18~40µm), and subsequently, a 2nd electrode metal (0.5~1µm) was sputtered on the Al2O3 layer. Advanced wire bonding was used to assemble CCW to PCB pads for electrical connections required capacitors. Electrical simulations were used to characterize CCW in terms of electrical performances. The capacitance measurements were compared between CCW & MLCC in conjunction with electrical simulation at high frequencies for RF & HPC applications. CCW can also be embedded into PCB and integrated into package chips.

Injectable Devices for Delivery of Liquid or Solid Protein Formulations

Sustained delivery of protein therapeutics remains a largely unsolved problem across anatomic locations. Miniaturized devices that can provide sustained delivery of protein formulations have the potential to address this challenge via minimally invasive administration. In particular, methodologies that can optimize protein formulation independent of device manufacture have the greatest potential to provide a platform suitable for wide applications. The techniques developed here demonstrate the fabrication of tubular devices for sustained release of protein therapeutics. Utilizing a dip-casting process, fine-scale tubes can be reliably produced with wall thickness down to 30 μm. Techniques were developed that enabled effective loading of either solid or liquid formulations, while maintaining a cylindrical form-factor compatible with placement in a 22-gauge needle. Further, highly compacted protein pellets that approach the expected density of the raw materials were produced with a diameter (∼300 μm) suitable for miniaturized devices. Release from a solid-loaded device was capable of sustaining release of a model protein in excess of 400 days. Given significant interest in ocular applications, intravitreal injection was demonstrated in a rabbit model with these devices. In addition, to simulate repeated injections in ocular applications, serial intravitreal injection of two devices in a rabbit model demonstrated acceptable ocular safety without significant intraocular inflammation from clinical exam and histology.

Investigation of the Ordered Structure in Partially Melted Isotactic Polypropylene.

The ordered structure of partially melted isotactic polypropylene (iPP) was investigated using polarized optical microscopy (POM) and small-/wide-angle X-ray scattering (SAXS/WAXS) measurements. The crystalline morphology was first examined by means of pulling a glass fiber through the iPP melt, which was generated by partially melting a preformed spherulite. The results from the POM experiments indicated that, even at a minimal pulling rate, the surviving ordered structure could also relocate along the direction of fiber pulling and grow into cylindrites eventually. In addition, during the quiescent crystallization from the partially melted sample, which had the same thermal history of fiber-pulling experiments, the obvious memory effect of melt was also observed from the results of X-ray experiments. Moreover, the SAXS profile derived from the partially melted iPP at 170 °C was fitted by the theory of scattering amplitude with the cylindrical form factor. The fit result implied that the surviving ordered structure is of cylindrical nanocrystals with a diameter D ≈ 30 ± 3 nm and height h ≈ 45 ± 3 nm, which can significantly influence the crystallization morphology and kinetics during the subsequent crystallization process.

A Shear-Stress Sensor for Hypersonic Flow Measurement

A shear-stress or skin-friction sensor for hypersonic flow measurements is presented. The sensor measures the displacement of a spring-mounted rectangular plate using a differential capacitance-based detection scheme. The 1.8-mm $\times $ 1.8-mm sensor is fabricated using a silicon-on-insulator wafer with a 20- $\mu \text{m}$ -thick epitaxial layer and packaged into a cylindrical form-factor with a 1/4-in diameter. Wall-shear-stress measurements are performed at a Mach-2.3 supersonic wind-tunnel facility at The University of Arizona. The sensors observe several features anticipated from hypersonic/supersonic flow physics, including the passing of normal shocks and the reversal of measured shear polarity when flow separation is deliberately induced via the use of a compression ramp. Furthermore, the measured value for dc wall-shear stress agrees with the model predictions for fully developed turbulent boundary layers. [2018-0191]

Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactive growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron microscopy observations but also provide additional information on the large scale size and shape distribution of the nanostructured components.

Designing Auto-Injectors for Children: Effect of Form Factor on the Human Factors of Efficient Drug Delivery

Because commercially available epinephrine auto-injectors differ in form factor, and are important for children the goal of this study was to evaluate their effect on human factors of efficient drug delivery in children. Auto-injectors with 3 different form factors (cylindrical, elliptical, and prismatic) were tested in a laboratory-based repeated measures experiment with 20 participants (aged 8-12 years). Participants applied their maximum possible force onto a force plate positioned over their thigh (maximum force capability task) and practiced an injection using the trainer auto-injector after watching the device’s training video (application task). Participants rated force confidence and preference for all devices. For the maximum force capability task, the elliptical device exhibited significantly higher axial-applied force compared with the prismatic device (43N vs 38N, respectively). The elliptical device also exhibited the lowest difference between force and device angle compared with the other two devices (1º vs 6º and 12º). For the application task, the elliptical device had the fastest time to force. The elliptical and prismatic devices had significantly lower grip effort compared to the cylindrical. The cylindrical form factor was the least preferred. Overall, these general patterns across form factors were similar to patterns observed in a previous study of adults. However,children exhibited lower force, higher grip effort, higher force angle, and more variability in application force, force angle, and grip effort. General trends were similar between adults and children. The results suggest that the elliptical form factor may have better success in drug delivery in children.

High-efficiency microstructured semiconductor neutron detectors for direct 3He replacement

High-efficiency Microstructured Semiconductor Neutron Detectors (MSNDs) have been tiled and arranged in a cylindrical form factor in order to serve as a direct replacement to aging and increasingly expensive 3He gas-filled proportional neutron detectors. Two 6-in long by 2-in diameter cylinders were constructed and populated with MSNDs which were then directly compared to a 4atm Reuter Stokes 3He detector of the same dimensions. The Generation 1 MSND-based 3Helium-Replacement (HeRep Mk I) device contained sixty-four 1-cm2 active-area MSNDs, each with an intrinsic neutron detection efficiency of approximately 7%. A Generation 2 device (the HeRep Mk II) was populated with thirty 4-cm2 active-area MSNDs, with an intrinsic thermal neutron detection efficiency of approximately 30%. The MSNDs of each HeRep were integrated to count as a single device. The 3He proportional counter and the HeRep devices were tested while encased in a cylinder of high-density polyethylene measuring a total of 6-in by 9-in. The 3He counter and the HeRep Mk II were each placed 1m from a 54-ng 252Cf source and tested for efficiency. The 3He proportional counter had a net count rate of 17.13±0.10cps at 1m. The HeRep Mk II device had a net count rate of 17.60±0.10cps, amounting to 102.71±2.65% of the 3He gas counter while inside of the moderator. Outside of moderator, the 3He tube had a count rate of 3.35±0.05cps and the HeRep Mk II device reported 3.19±05, amounting to 95.15±9.04% of the 3He neutron detector.

Hydrogen trapping at dislocation cores at room temperature in deformed Pd

Abstract Small-angle neutron scattering (SANS) measurements of hydrogen segregation at dislocations in heavily deformed single crystal Pd have been performed at very low solute concentration (PdH0.0016) at equilibrium with respect to hydrogen gas at 295 K. The net (the without-hydrogen measurement subtracted from with-hydrogen measurement) absolute differential macroscopic scattering cross section has been fit with a cylindrical form factor to represent the Cottrell atmosphere, yielding local trapped concentration δ ∼ 0.06 [H]/[Pd], local volumetric dilatation f ∼ 1.01, and trapping radius R ∼ 4 A of the segregated hydrogen. This measurement augments SANS results below ambient temperature [B.J. Heuser, H. Ju, Phys. Rev. B 83 (2011) 094103]. The temperature dependence of the measured radius is confirmed by a Fourier transform of hydrogen occupation at dislocations based on an elastic continuum treatment [Trinkle et al., Phys. Rev. B 83 (2011) 174116]. The measured trapping parameters are consistent with a depopulation of weak long-range dislocation strain fields at ambient temperature; hydrogen binding to stronger core dislocation sites persists at 295 K and results in the measured net scattering. The local solute concentration and trapping radius (less than two Burgers vectors in Pd), are both too small to support optic mode dispersion due to inter-hydrogen interactions. This result supports the conclusion that trapped hydrogen undergoes a hydride to solid solution phase transformation between 200 and 300 K based on hydrogen vibration density of states measurements using incoherent inelastic neutron scattering [Trinkle et al., Phys. Rev. B 83 (2011) 174116, Ju et al., Nucl. Instr. Meth. Phys. Res. A 654, (2011) 522, and Heuser et al., Phys. Rev. B 78 (2008) 214101].

Solution Structural Characterization of Coiled-Coil Peptide–Polymer Side-Conjugates

Detailed structural characterization of protein-polymer conjugates and understanding of the interactions between covalently attached polymers and biomolecules will build a foundation to design and synthesize hybrid biomaterials. Conjugates based on simple protein structures are ideal model system to achieve these ends. Here we present a systematic structural study of coiled-coil peptide-poly(ethylene glycol) (PEG) side-conjugates in solution, using circular dichroism, dynamic light scattering, and small-angle X-ray scattering, to determine the conformation of conjugated PEG chains. The overall size and shape of side-conjugates were determined using a cylindrical form factor model. Detailed structural information of the covalently attached PEG chains was extracted using a newly developed model where each peptide-PEG conjugate was modeled as a Gaussian chain attached to a cylinder, which was further arranged in a bundle-like configuration of three or four cylinders. The peptide-polymer side-conjugates were found to retain helix bundle structure, with the polymers slightly compressed in comparison with the conformation of free polymers in solution. Such detailed structural characterization of the peptide-polymer conjugates, which elucidates the conformation of conjugated PEG around the peptide and assesses the effect of PEG on peptide structure, will contribute to the rational design of this new family of soft materials.

Time-resolved small angle X-ray scattering study of sol–gel precursor solutions of lead zirconate titanate and zirconia

The evolution of nanostructure in sol–gel derived lead zirconate titanate (PZT) and zirconia precursor sols at different hydrolysis ratios was investigated by small angle X-ray scattering (SAXS). The shape of the clusters in the zirconia sol could be described by the length-polydisperse cylindrical form factor. The zirconia-based clusters were characterized by a cross-sectional radius, r0, of 0.28nm and a practically monodisperse length of ca. 1.85nm. These clusters were probably constructed of zirconia-related tetrameric building blocks. Similar cylindrical structural motifs were observed in PZT precursor sols with [H2O]/[Zr+Ti]=9.26 and 27.6, but the polydispersity in length was much higher. Clear scattering contributions from Ti and Pb centers were not detected, which was interpreted in terms of a homogeneous distribution of unbound lead ions in solution and the relatively low scattering intensity from any Ti-based clusters or oligomers that may have been present in the sols.

A Quasistatic Antenna Design Approach for Minimum-Q Antennas

The quasistatic antenna-design algorithm uses electrostatic methods to calculate the antenna's shape. The asymptotic conical dipole is a classic quasistatic design. A charged disk is added to the asymptotic conical dipole to model a thick top-loaded monopole. The antenna's shape is an equipotential surface. The disk height and radius control the width and height of the top load. The minimum Q for this design is lower than the ideal thin-disk-loaded monopole. A Computer Simulation Technology model confirmed the predicted Q value of twice Chu's limit. Measurements on a 16-wire, 0.5 m physical antenna agreed with the NEC 4 model. The tradeoff in Q and radiation resistance is illustrated with detailed examples. Several designs have a lower Q than the ideal thin-disk-loaded monopole. This design approach gives a very good design with only two degrees of freedom. The computational time for the algorithm is a small fraction of one NEC 4 modeling run. The algorithm can be extended to design antennas with a cylindrical, elliptical, or conical form factor.

Small-angle neutron scattering measurements of hydrogen and deuterium trapping at dislocations in deformed single-crystalline Pd at low temperature

Small-angle neutron scattering (SANS) measurements of hydrogen and deuterium trapped at dislocation defects in deformed single-crystalline Pd have been performed at 15, 100, and 200 K at total interstitial solute concentrations of order ${10}^{\ensuremath{-}3}$. This work supports recent incoherent inelastic neutron scattering measurements of the vibrational density of states of trapped hydrogen under similar concentration-temperature conditions [Heuser et al., Phys. Rev. B 78, 214101 (2008)]. The measured net absolute macroscopic differential scattering cross sections have been fitted with a cylindrical form factor representing solute-decorated dislocation line segments. Generally, very little difference in the measured cross sections was observed with temperature for a given solute type, while a significant change was observed between hydrogen- and deuterium-loaded samples. The latter difference is understood within a cross-section model that takes into account the local lattice dilatation associated with solute segregation at dislocations. The application of the model cross section to the net PdH${}_{0.0013}$ SANS response yields an effective trapping radius of $R$ \ensuremath{\sim} 10 \AA{} and dislocation density of ${\ensuremath{\rho}}_{d}~{10}^{10}$ cm${}^{\ensuremath{-}2}$. Analysis of the SANS response allowed the local trapped solute concentration (\ensuremath{\sim}0.5 [H]/[Pd]) and volumetric dilatation (\ensuremath{\Delta}\ensuremath{\nu}/\ensuremath{\Omega} \ensuremath{\sim} 1.1) to be determined with the constraint that the system locally satisfies the known lattice expansion of Pd hydride (i.e., Vegard's law).

Scattering Study of the Structure of Polystyrene Sulfonate Comb Polyelectrolytes in Solution

AbstractThe structures of a range of PSS combs in aqueous solutions were characterized using SLS, DLS, SANS and SAXS. Combined SLS and SANS data indicated that the comb polyelectrolytes adopted extended cylindrical structures in dilute solutions. The degree of extension of the side‐chains was analyzed by fitting the data with a novel cylindrical form factor using a variable number density of monomers. The results were in agreement with hydrodynamic radii from DLS measurements. Addition of salt to the samples caused a contraction of the cylindrical morphology, but the chains continued to adopt relatively extended conformations. In semi‐dilute solutions a universal behaviour, independent of the comb topology, was found for the screening length in SAXS measurements.magnified image

Effect of Dwarf Mistletoe on Bole Taper and Volume in Young Douglas-Fir

Abstract Boles of 210 residual understory Douglas-fir trees, ranging from uninfected to heavily infected with Douglas-fir dwarf mistletoe, were measured for cylindrical form factor, Girard form class, height-to-diameter ratio, bole profile, and volume. Height-to-diameter ratio and Girard form class were significantly reduced by dwarf mistletoe across the range of infection classes. However, no effect due to infection by dwarf mistletoe was found on cylindrical form factor, and only a slight difference in bole profile between uninfected and heavily infected trees was found. These results suggest that dwarf mistletoe increases bole taper and affects the volume of younger Douglas-fir by affecting tree diameter and height but not by a substantive change in bole profile. West. J. Appl. For.16(1):5–8.

Crystal Chemistry of Nanotubes Lattices

X-ray diffraction profiles of pristine and hypothetical “intercalated” crystalline bundles of single-wall carbon nanotubes are computed and compared with experiment. The pristine case is complicated by finite size effects, tube diameter dispersion and the cylindrical form factor for uncorrelated tube rotations. Experimental profiles of “doped” samples are not in agreement with simulations based on 2-D ordered sublattices except at very low doping levels.

Detection of TPA-silicalite precursors nucleated during the room temperature aging of a clear homogeneous synthesis solution

The transformations occurring during the aging of a clear silicalite preparation at room temperature were studied by small angle X-ray (SAXS) and neutron scattering (SANS), X-ray diffraction and IR spectroscopy. Particles with a radius of gyration of 28 A were detected in a solution that was aged at room temperature for six months. A cylindrical form factor provided the best fit to the experimental scattering functions and so a similar particle morphology to that formed during the initial stages of the hydrothermal synthesis at 100 °C can be presumed. The IR spectrum of a freeze dried sample taken from the aged solution shows a band at 560 cm−1 characteristic of the framework structure of silicalite, and a SANS contrast variation study showed that the scattering species contain the tetrapropylammonium template. The time required for the hydrothermal crystallisation of silicalite was significantly reduced by aging the silicalite preparation prior to heating to 100 °C.

TPA−Silicalite Crystallization from Homogeneous Solution: Kinetics and Mechanism of Nucleation and Growth

The formation and growth of tetrapropylammonium-templated crystal nuclei of silicalite from a clear homogeneous solution was recorded in situ as a function of time at temperatures between 90 and 115 °C using small-angle X-ray scattering (SAXS). The kinetics of the nucleation process was studied and give an apparent activation energy of 70 kJ mol-1. A small-angle neutron scattering (SANS) contrast variation study confirms that the nuclei contain the tetrapropylammonium template in the expected stoichiometry of the completed crystal. Infrared spectroscopy provides evidence that the silicalite framework structure is present in the nuclei. Our SAXS and SANS data both show that a cylindrical form factor gave the best fit to the measured scattering functions for the particles that developed from nucleation to the end of the induction period. Dynamic light scattering measurements were used to follow the crystal growth in the 100−6000 A size domain, beyond the range of the SAXS measurements. Scanning electron mic...

Long-term effects of superphosphate fertilization on stem form, taper and stem volume estimation of Pinus radiata

The long term effects of superphosphate fertilization on stem form, taper and stem volume estimation of Pinus radiata on a phosphorus-deficient site was examined using data from a fertilizer experiment which had been maintained for 30 years. The application of superphosphate resulted in long term and statistically significant changes in stem form. Mean cylindrical form factor ranged from 0.33 for the control trees up to 0.40 for trees fertilized with 100 kg P ha −1. Stem form was also examined through taper curves which provided detailed depiction of average relative stem profiles. The increase in cylindrical form factor of fertilized trees was largely attributed to a significantly broader profile of the lower third of the stem. In comparison with the control trees, the fertilized trees also had a broader, although not statistically significant, profile of upper and middle stem which could also contribute to the increase in their cylindrical form factor. With increased form factor a greater proportion of the stem became merchantable because of increased log length to tree height ratio. Mean average taper of trees did not show a consistent trend with increasing lelevels of superphosphate application. It largely reflected the differential response of DBH and height growth to the treatments. The volume equation based on control trees underestimated the underbark stem volume of fertilized trees by 5–12% on average. Developing separate volume equations for the fertilized trees is warranted.