Lateral Phase Research Articles

RADIOGRAPHIC THORACIC ANATOMY OF THE RED PANDA (AILURUS FULGENS)

The red panda ( Ailurus fulgens ) is classified as an endangered species by the International Union for Conservation of Nature and Natural Resources. The natural distribution of the red panda is in the Himalayas and southern China. Thoracic diseases such as dirofilariasis, hypertrophic cardiomyopathy, tracheal obstruction, lung worm infestation, and pneumonia have been reported in the red panda. The aim of this study was to describe the normal radiographic thoracic anatomy of captive red pandas as a species-specific reference for routine health examinations and clinical cases. Right lateral (RL) and dorsoventral (DV) inspiratory phase views of the thorax were obtained in 11 adult captive red pandas. Measurements were made and ratios calculated to establish reference ranges for the mean vertebral heart score on the RL (8.34 ± 0.25) and DV (8.78 ± 0.34) views and the mean ratios of the caudal vena cava diameter to the vertebral body length above tracheal bifurcation (0.67 ± 0.05) and tracheal diameter to the width of the third rib (2.75 ± 0.24). The majority of animals (10/11) had 14 thoracic vertebrae, except for one animal that had 15 thoracic vertebrae. Rudimentary clavicles were seen in 3/11 animals. The ovoid, oblique cardiac silhouette was more horizontally positioned and elongated in older animals. A redundant aortic arch was seen in the oldest animal. The trachea was seen with mineralized cartilage rings in all animals. The carina was clearly seen in the majority of animals (10/11). Variations exist in the normal radiographic thoracic anatomy of different species. Knowledge of the normal radiographic thoracic anatomy of the red panda should prove useful for routine health examinations and in the diagnosis of thoracic diseases.

Structure and magnetic properties of Zr–Mn substituted strontium hexaferrite Sr(Zr,Mn) x Fe12−2x O19 nanoparticles synthesized by sol–gel auto-combustion method

In this research, nano-sized powders of Zr–Mn substituted strontium hexaferrite (Sr(Zr,Mn) x Fe12−2x O19 (x = 0, 2, 2.5, 3)) were synthesized by sol–gel auto-combustion route using subsequent heat treatment. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Mössbauer spectroscopy and vibration sample magnetometer (VSM) techniques. XRD and Mössbauer spectroscopy results revealed formation of Sr(Zr,Mn) x Fe12−2x O19 accompanied with Mn δ Fe2−δ O4 lateral phase in the samples. Also, FTIR and XRD results demonstrated presence of SrO impurity phase. FESEM micrographs show particle size reduction and presence of two distinct powder morphologies with different brightness levels with Zr4+ and Mn2+ substitutions which approves existence of lateral phases in the substituted samples. TEM micrographs show nanometric particles with sizes smaller than 100 nm with high crystallinity. Mössbauer results showed that at low level of substitution, Zr4+ ions prefer to occupy both 4f1 and 2b however, at higher level of substitution, they prefer exclusively 4f1 site. While, Mn2+ ions distributed approximately equally between 12k and 2a sites. The presence of nonmagnetic Zr4+ cation leads to decrease in exchange interaction, especially at 12k and 2a sites. VSM results showed decrement of coercivity force ( i H c ) from 5593.60 to 3282.46 Oe and maximum magnetization from 62.60 to 46.15 emu g−1, respectively, by increment of Zr–Mn substitution values. Variations in maximum magnetization magnitude have been explained on the basis of occupation of the substituted cations at different iron sites.

Phase constituents and magnetic properties of the CoFe2O4 nanoparticles prepared by polyvinylpyrrolidone (PVP)-assisted hydrothermal route

In this research, nanoparticles of cobalt ferrite were synthesized by a simple hydrothermal process at 190 °C using different treatment durations with the assistance of polyvinylpyrrolidone (PVP) surfactant. The synthesized powders were characterized using X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscope and vibration sample magnetometer techniques. The quantitative values of phase constituents and also inversion parameter of cobalt ferrite spinel structure were calculated by Rietveld method using XRD results. XRD results show formation of cobalt ferrite as the main phase in all samples and also the presence of small amounts of Co3O4 lateral phase in some cases. Raman spectroscopies also confirm the presence of this lateral phase. Microstructural studies represent formation of nanoparticles with a narrow particle size distribution. Magnetic measurements represent that maximum magnetization (Mmax) values are in the range of 25–57 emu/g with changes in the hydrothermal treatment duration. Intrinsic coercivity force values (iHc) change from 0 to 487 Oe in different samples. The highest Mmax value of 57 emu/g was obtained in the sample after 3 h of hydrothermal treatment with PVP addition. The iHc value of this sample was 35 Oe, while without PVP addition, the high Mmax value of 60 emu/g is observed in a sample that has iHc value equal to 320 Oe.

Chimeric lipid/block copolymer nanovesicles: Physico-chemical and bio-compatibility evaluation

Chimeric systems are mixed nanovectors composed by different in nature materials and exhibit new functionalities and properties. The particular chimeric nanovectors, formed by the co-assembly of low and high molecular weight amphiphiles, have the potential to be utilized as drug delivery platforms. We have utilized two lipids, l-α-phosphatidylcholine, hydrogenated (Soy)(HSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and a poly(oligoethylene glycol acrylate)-b-poly(lauryl acrylate) (POEGA-PLA) block copolymer, at different molar ratios, in aqueous media. Light scattering, differential scanning calorimetry (DSC) and imaging techniques (cryo-TEM, AFM) were employed in order to elucidate the structure and properties of the nanostructures, as well as the cooperativity between the components. DSC experiments showed considerable interaction of the block copolymer with the lipid bilayers and suggested an inhomogeneous distribution of the copolymer chains and lateral phase separation of the components. Vesicle formation was observed in most cases by cryo-TEM with a chimeric membrane exhibiting kinks, in accordance with DSC data. A series of biocompatibility experiments indicated good in vitro biological stability and low cytotoxicity in vivo of the novel nanocarriers. Finally, ibuprofen (IBU) was used as model drug in order to study the loading and the release properties of the prepared chimeric lipid/block copolymer vesicles.

Investigation and solution of low yield problem for phase change memory with lateral fully-confined structure**Project supported by the National Basic Research Program of China (No. 2011CB922103), the National Natural Science Foundation of China (Nos. 61376420, 61404126, A040203), and the Science and Technology Project of Shenzhen (No. JCYJ20140509172609175).

This paper mainly focuses on solving the low yield problem for lateral phase change random access memory with a fully confined phase change material node. Improper over-etching and bad step-coverage of physical vapor deposition were the main reasons for the poor contact quality, which leads to the low yield problem. Process improvement was carried out to better control over-etching within 10 nm. Atomic layer deposition process was used to replace physical vapor deposition to guarantee good step coverage. Contrasting cross-sectional photos taken by scanning electron microscopy showed great improvement in contact quality. The atom layer deposition process was demonstrated to have good prospects in nano-contact for phase change memory application.

The effect of poly vinyl alcohol (PVA) surfactant on phase formation and magnetic properties of hydrothermally synthesized CoFe2O4 nanoparticles

Nanoparticles of CoFe2O4 were synthesized by hydrothermal process at 190°C with and without poly vinyl alcohol (PVA) addition using treatment durations of 1.5–6h. The synthesized powders were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and vibration sample magnetometer (VSM) techniques. XRD results show presence of CoFe2O4 as the main phase and Co3O4 as the lateral phase in some samples. The results show that in the samples synthesized without PVA addition considerable amount of lateral phase is present after 3h of hydrothermal treatment while with PVA addition this phase is undetectable in the XRD patterns of the sample synthesized at the same conditions. Microstructural studies represent increasing of particle size with increasing of hydrothermal duration and formation of coarser particles with PVA addition. The highest maximum magnetization (Mmax) values in both of the samples that were synthesized with and without PVA addition are about 59emu/g that were obtained after 4.5h of hydrothermal treatment. Intrinsic coercive field (iHc) value of the sample without PVA addition increases from 210 to 430Oe. While with PVA addition the iHc value changes from 83Oe to 493Oe. The mechanism of changes in Mmax and iHc values has been explained.

Phase Diagrams and Ordering in Charged Membranes: Binary Mixtures of Charged and Neutral Lipids.

We propose a model describing the phase behavior of two-component membranes consisting of binary mixtures of electrically charged and neutral lipids. We take into account the structural phase transition (main-transition) of the hydrocarbon chains, and investigate the interplay between this phase transition and the lateral phase separation. The presence of charged lipids significantly affects the phase behavior of the multicomponent membrane. Due to the conservation of lipid molecular volume, the main-transition temperature of charged lipids is lower than that of neutral ones. Furthermore, as compared with binary mixtures of neutral lipids, the membrane phase separation in binary mixtures of charged lipids is suppressed, in accord with recent experiments. We distinguish between two types of charged membranes: mixtures of charged saturated lipid/neutral unsaturated lipid and a second case of mixtures of neutral saturated lipid/charged unsaturated lipid. The corresponding phase behavior is calculated and shown to be very different. Finally, we discuss the effect of added salt on the phase separation and the temperature dependence of the lipid molecular area.

Turbulence-induced bubble collision force modeling and validation in adiabatic two-phase flow using CFD

The prediction capability of the two-fluid model for gas–liquid dispersed two-phase flow depends on the accuracy of the closure relations for the interfacial forces. In previous studies of two-phase flow Computational Fluid Dynamics (CFD), interfacial force models for a single isolated bubble has been extended to disperse two-phase flow assuming the effect in a swarm of bubbles is similar. Limited studies have been performed investigating the effect of the bubble concentration on the lateral phase distribution. Bubbles, while moving through the liquid phase, may undergo turbulence-driven random collision with neighboring bubbles without significant coalescence. The rate of these collisions depends upon the bubble approach velocity and bubble spacing. The bubble collision frequency is expected to be higher in locations with higher bubble concentrations, i.e., volume fraction. This turbulence-driven random collision causes the diffusion of the bubbles from high concentration to low concentration. Based on experimental observations, a phenomenological model has been developed for a “turbulence-induced bubble collision force” for use in the two-fluid model. For testing the validity of the model, two-phase flow data measured at Purdue University are utilized. The geometry is a 10mm×200mm cross section channel. Experimentally, non-uniform inlet boundary conditions are applied with different sparger combinations to vary the volume fraction distribution across the wider dimension. Examining uniform and non-uniform inlet data allows for the influence of the volume fraction to be studied as a separate effect. The turbulence-induced bubble collision force has been implemented in ANSYS CFX. The assessment results show agreement with the measured data, correctly capturing the redistribution of volume fraction downstream with uniform and non-uniform inlet profiles. In particular, for the non-uniform data, the transverse redistribution of volume fraction at downstream locations is captured. This signifies the importance of bubble–bubble collision phenomena in correctly predicting volume fraction distributions.

Grazing incidence resonant soft X-ray scattering for analysis of multi-component polymer-fullerene blend thin films

Grazing incidence small angle X-ray scattering (GISAXS) methods are frequently very successfully utilized for morphological investigations of thin polymer blend films used in organic photovoltaics. However, conventional GISAXS does no longer provide material sensitivity when the blend consists of more than two components due to the contrast conditions. In case of multi-component blends the use of grazing incidence resonant soft X-ray scattering (GI-RSoXS) can overcome such problems. In this work we exemplarily apply GI-RSoXS to investigate simultaneously the vertical and lateral morphology of polymer-fullerene bulk heterojunction layers made from poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2,6-diyl]] (PCPDTBT) and [6,6]-penyl-C 61 butyric acid methyl ester (PCBM) with added photosensitizer perylene diimide (PDI) with and without use of the solvent additive 1,8-octanedithiol (ODT). The investigation reveals that films without solvent additive ODT tend to show only vertical phase separation while films prepared with solvent additive also phase separate laterally. PDI seems to assist lateral phase separation between PCPDTBT and PCBM by expelling PCBM from the amorphous polymer matrix.

Anisotropic Charge-Carrier Transport in High-Mobility Donor-Acceptor Conjugated Polymer Semiconductor Films.

Many high-performance solution-processable polymer thin-film transistors (PTFTs) have been reported. This contribution presents a comparative study of oriented films that have been deposited by means of solution shearing (SS) with charge-carrier transport anisotropy for PTFTs based on a diketopyrrolopyrrole-thiazolothiazole donor-acceptor copolymer (PDPPTzBT). The maximum field-effect mobility of the SS film of PDPPTzBT was 10.00 cm2 V-1 s. We also blended a solution of PDPPTzBT with a solution of polystyrene (PS). Solvent vapor annealing (SVA) lateral phase separation was adopted to block carrier transport in the direction of π-π stacking, and further evidence of charge transport anisotropy was provided. Highly oriented polymer films will further influence the carrier transport anisotropy and promote carrier transport along the backbone, and the performance of the field-effect transistor is thus improved.

White-light quantitative phase imaging unit

We introduce the white-light quantitative phase imaging unit (WQPIU) as a practical realization of quantitative phase imaging (QPI) on standard microscope platforms. The WQPIU is a compact stand-alone unit which measures sample induced phase delay under white-light illumination. It does not require any modification of the microscope or additional accessories for its use. The principle of the WQPIU based on lateral shearing interferometry and phase shifting interferometry provides a cost-effective and user-friendly use of QPI. The validity and capacity of the presented method are demonstrated by measuring quantitative phase images of polystyrene beads, human red blood cells, HeLa cells and mouse white blood cells. With speckle-free imaging capability due to the use of white-light illumination, the WQPIU is expected to expand the scope of QPI in biological sciences as a powerful but simple imaging tool.

Fabrication process not limited by the lithography resolution of lateral phase change memory

To improve the performance of phase change memory (PCM) and reduce the cost of fabrication, we propose a new lateral PCM structure based on the technology of angle evaporation to define the critical dimension controllable, not limited by the limitation of lithography resolution. The fabrication process is cost-effective. PCM cells featured 80nm×100nm were successfully demonstrated, although the resolution of the aligned used was 1µm only. Compared with the traditional lateral PCM structure, finite element simulation results show that the new structure has better thermal stability.

Automated phase attribute-based picking applied to reflection seismics

We have applied an attribute-based autopicking algorithm to reflection seismics with the aim of reducing the influence of the user’s subjectivity on the picking results and making the interpretation faster with respect to manual and semiautomated techniques. Our picking procedure uses the cosine of the instantaneous phase to automatically detect and mark as a horizon any recorded event characterized by lateral phase continuity. A patching procedure, which exploits horizon parallelism, can be used to connect consecutive horizons marking the same event but separated by noise-related gaps. The picking process marks all coherent events regardless of their reflection strength; therefore, a large number of independent horizons can be constructed. To facilitate interpretation, horizons marking different phases of the same reflection can be automatically grouped together and specific horizons from each reflection can be selected using different possible methods. In the phase method, the algorithm reconstructs the reflected wavelets by averaging the cosine of the instantaneous phase along each horizon. The resulting wavelets are then locally analyzed and confronted through crosscorrelation, allowing the recognition and selection of specific reflection phases. In case the reflected wavelets cannot be recovered due to shape-altering processing or a low signal-to-noise ratio, the energy method uses the reflection strength to group together subparallel horizons within the same energy package and to select those satisfying either energy or arrival time criteria. These methods can be applied automatically to all the picked horizons or to horizons individually selected by the interpreter for specific analysis. We show examples of application to 2D reflection seismic data sets in complex geologic and stratigraphic conditions, critically reviewing the performance of the whole process.

Direct formation of nano-pillar arrays by phase separation of polymer blend for the enhanced out-coupling of organic light emitting diodes with low pixel blurring.

We have demonstrated a simple and efficient method to fabricate OLEDs with enhanced out-coupling efficiencies and with low pixel blurring by inserting nano-pillar arrays prepared through the lateral phase separation of two immiscible polymers in a blend film. By selecting a proper solvent for the polymer and controlling the composition of the polymer blend, the nano-pillar arrays were formed directly after spin-coating of the polymer blend and selective removal of one phase, needing no complicated processes such as nano-imprint lithography. Pattern size and distribution were easily controlled by changing the composition and thickness of the polymer blend film. Phosphorescent OLEDs using the internal light extraction layer containing the nano-pillar arrays showed a 30% enhancement of the power efficiency, no spectral variation with the viewing angle, and only a small increment in pixel blurring. With these advantages, this newly developed method can be adopted for the commercial fabrication process of OLEDs for lighting and display applications.

Small roll angle measurement using lateral shearing cyclic path polarization interferometry.

We present a technique for the measurement of roll angular displacement of a rotary stage using a lateral shearing cyclic path optical configuration (CPOC) setup and polarization phase shifting interferometry (PPSI). The CPOC setup, aligned on the rotary stage, laterally shears the input plane polarized spherical beam into a pair of orthogonally polarized beams, which when brought to the same state of polarization by a polarizer produce interference fringes similar to Young's fringes. Rotation of the CPOC setup in its plane introduces a phase change between the orthogonally polarized lateral sheared beams due to the change in angle of incidence of the input beam. The change in the phase results in spatial displacement of the interference fringes. Using PPSI, the phase, or the optical path difference change between the laterally sheared beams that is related to the rotation angle of the CPOC setup, is measured.

Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition (CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and confirmed analytically in the boron deposition temperature range from 700 °C down to 400 °C. For this temperature range the local loading effect of the boron deposition is investigated on the micro scale. A LB = 2.2 mm was determined for boron deposition at 700 °C, while a LB of less than 1 mm was observed at temperatures lower than 500 °C.

The Role of Lipid Rafts in the Localization and Function of the Chemosensory TRPA1 Channel

Lipid rafts are highly specialized membrane domains characterized by high concentrations of cholesterol, sphingolipids and gangliosides. This distinctive composition results in lateral phase separation and generation of a liquid-ordered domains accommodating various receptors and channels involved in numerous cellular processes. Recently, several members of the Transient Receptor Potential channels superfamily (TRPCs, TRPM8, and TRPV1) have been shown to locate mainly in the lipid rafts and that this compartmentalization modulates their activation properties. Yet, not much is known about localization and interactions of TRPA1 with the surrounding plasma membrane. Since TRPA1 can be gated by a large number of electrophilic and non-electrophilic compounds, as well as by physiological stimuli such as cold we hypothesize that its localization in the lipid rafts could be a crucial factor influencing the channel activity. Exploiting microscopy and biochemical approaches, this study provides evidence for TRPA1 localization in lipid rafts. TIRF microscopy experiments in HEK293T cells transfected with a mouse or human TRPA1 channel carrying a C-terminal mCherry tag indicate high co-localization rate between channel and the lipid raft maker cholera toxin subunit B. Density gradient centrifugation of Triton-X insoluble fractions confirmed co-expression of TRPA1 and the lipid raft marker flotillin-2 in the low density membrane fractions. Lipid raft disruption experiments further affirmed the cholesterol-related localization of the channel, shifting its localization into higher density gradients. Modification of lipid rafts composition by cholesterol depletion (methyl-b-cyclodextrin) or sphingolipids hydrolysis (sphingomyelinase) decreased the responses of TRPA1 to lipopolysaccharides, thymol, allyl isothiocyanate and cold. Taken together, these results indicate that TRPA1 is present in lipid rafts and this location is essential for its normal activation by different agonists.

Lateral Phase Behavior of Human Skin Lipids

The human stratum corneum (SC) is the outermost layer of the epidermis, the first barrier against the environment. This largely impenetrable layer consists of anucleated, flattened, protein-rich cells called corneocytes suspended in an extracellular lipid matrix. This lipid matrix is composed of ceramides (Cers), cholesterol (Chol), and free fatty acids (FFAs). The SC lipids are unique from other biologically relevant lipids commonly found in cell membranes in that the Cers and FFAs have very long (>20 carbons) fatty acid chains, nearly all of which are fully saturated. Using surface pressure vs. molecular area isotherms and fluorescence microscopy, our research investigates the lateral packing and domain formation within Langmuir monolayers of the individual Cer, Chol, and FFA components and their binary and ternary mixtures to determine the role of each component in the material properties of the SC layer. Particular attention is paid to the effect of FFA length on membrane fluidity – FFA chains ranging from 16 to 30 carbons (24 carbons being the most common in the SC) were studied. We show that longer FFAs have a condensing effect in Cer monolayers, while Chol tends to disrupt this Cer-FFA organization. We also demonstrate the differences between the canonical 1:1:1 Cer:Chol:FFA mixture and more physiologically accurate mixtures in which Cers and Chol are in higher concentrations and several FFAs of different chain length are present.

Bending Moduli of Ternary Mixture Models of the Cell Plasma Membrane

Cells must be able to maintain and change membrane shape. This membrane curvature can be influenced by any lateral phase heterogeneity. Ternary mixtures of high-melting lipid, low-melting lipid, and cholesterol exhibit a region of liquid-ordered (Lo)+ liquid-disordered (Ld) phase coexistence analogous to raft + non-raft behavior in cells. Although curvature can induce separation and sorting in vitro, a number of highly-curved membranes in vivo have raft-like composition, which is puzzling since the raft-like compositions have greater rigidity in lipid model mixtures. We find that including transmembrane helical WALP peptides as a component of the model mixtures greatly changes their bending behavior. Measurements were made by shape analysis of giant unilamellar vesicles with both fluorescence and phase contrast microscopy. Vesicles of a single phase were made by the gentle hydration method to obtain a more narrow distribution of vesicle tensions than is obtained by electroformation. We find that a WALP peptide component rigidifies the liquid-disordered phase whereas the liquid-ordered phase is unaffected. This rigidifying effect might be related to the monolayers sliding relative to each other. Further, we have investigated the effects of peptides of different lengths and results suggest a role for hydrophobic mismatch of the peptide component relative to the bilayer thickness.

Synthesis of bottlebrush copolymers based on poly(dimethylsiloxane) for surface active additives

Abstract Bottlebrush polymers have been used as surface-active additives for chemically-identical linear polymers because they spontaneously accumulate at surfaces through an entropy-mediated process. In this work, we design functional bottlebrush polymer additives with mixed side-chain chemistries that can deliver unique surface properties. Bottlebrush polymers with poly(dimethylsiloxane) (PDMS) side-chains and bottlebrush copolymers with PDMS and poly(lactic acid) (PLA) side-chains are synthesized using ring opening metathesis polymerization. Contact angle goniometry, X-ray photoelectron spectroscopy (XPS), and microscopy demonstrate a spontaneous accumulation of these additives at the film surface without lateral phase segregation. Bottlebrush polymers were found to enrich the film surface more strongly than linear block copolymers of PDMS-b-PLA, and the surface contact angle was tunable by varying the composition and quantity of added bottlebrush copolymer. Significantly, bottlebrush additives segregate rapidly, during film casting. This work demonstrates that low-surface energy bottlebrush copolymer additives can be used to introduce new surface properties in polymer films.