Dual Morphology Research Articles

Synthesis and characterization of interpenetrating polymer network of polyglycidyl methacrylate and acrylamide using selenonium ylide as an initiator

Interpenetrating polymer network (IPN) based on polyglycidylmethacrylate (PGMA) and acrylamide (AAm) was synthesized using divinylbenzene (DVB) as a crosslinking agent and diphenylselenonium 2, 3, 4, 5-tetraphenylcyclopentadienylide (selenonium ylide) as a new radical initiator. A series of IPNs were prepared by varying the concentrations of AAm, PGMA, DVB and selenonium ylide in dioxan for 90 min at 80 ± 1 °C under an inert atmosphere of nitrogen. Dual phase morphology of the synthesized IPN was revealed by scanning electron microscopy (SEM). The properties like percentage swelling, average molecular weight of network between crosslinks (Mc) and young’s modulous were direct function of linear polymer [PGMA] and initiator [Ylide] where as inverse function of monomer [AAm] and crosslinker [DVB]. The differential scanning calorimetry (DSC) curve showed glass transition temperature at 127 °C. The synthesized IPN is thermally stable up to 450 °C. FTIR, 1H NMR and 13C NMR spectroscopic techniques were used for characterization of polyglycidylmethacrylate and IPN of polyglycidylmethacrylate (PGMA) and acrylamide (AAm). FTIR spectrum confirmed the presence of PGMA, AAm and DVB in the formed IPN by showing their characteristic bands. Similarly, 1H NMR and 13C NMR spectrum of the synthesized IPN also exhibit all characteristic peaks of PGMA, AAm and DVB in the formed IPN.

The evolution of number in Otomi

Otomi (Oto-Pamean, Oto-Manguean) is a small group of languages spoken in Mexico which has emerged as a linguistic family in recent times. In this paper, I study relevant changes in the number system of the Otomi languages. These changes constitute an interesting object of study to gain a better understanding of two main phenomena: aspects of language change involving the loss of the dual number; and the constraints on number agreement restricted to conjoining structures. I show that changes in the number system in the Otomi family have different outcomes depending on the dialectal area. Such outcomes include the loss of dual morphology through a semantic rearrangement where the old dual forms have become exponents of either paucal or plural number. In some of the varieties, the old dual is still preserved, but it is relegated to male speech as a token of partnership and camaraderie.

Bijel reinforcement by droplet bridging: a route to bicontinuous materials with large domains

Bijels are non-equilibrium solid-stabilized emulsions with bicontinuous arrangement of the constituent fluid phases. These multiphase materials spontaneously form through arrested spinodal decomposition in mixtures of partially miscible liquids and neutrally wetting colloids. Here, we present a new solid-stabilized emulsion with an overall bicontinuous morphology similar to a bijel, but with one continuous phase containing a network of colloid-bridged droplets. This dual morphology is the result of combined spinodal decomposition and nucleation and growth in a binary liquid mixture containing colloidal particles with off-neutral wetting properties and partial affinity for one liquid phase. The rheology of these systems, which we call bridged bijels, is nearly identical to their simple bijel counterparts, with a unique exponential dependence of the zero-shear elastic modulus on the colloid volume fraction. However, partitioning of the colloids between the spinodal surface and the fluid domains delays the onset of structural arrest, providing access to domain sizes much larger than available in simple bijels without loss of mechanical stability. This ability greatly expands the potential technological applications of these unique materials. In addition, our findings reveal new strategies for tuning the rheology of bijels and outline new directions for future fundamental research on this unique class of soft materials.

Is Dual Morphology of Rock‐Salt Crystals Possible with a Single Additive? The Answer Is Yes, with Barbituric Acid

Crystal face lift: barbituric acid is shown to be a new crystal-habit modifier for sodium chloride crystals. Two morphologies of salt crystals can be prepared separately with this new additive. It is of the few additives able to induce rhombic dodecahedron crystals for NaCl, and is required only a trace of amount, unlike other additives, such as glycine.

Is Dual Morphology of Rock‐Salt Crystals Possible with a Single Additive? The Answer Is Yes, with Barbituric Acid

Salz in unterschiedlichen Formen: Barbitursäure kann das Aussehen von Natriumchlorid-Kristallen modifizieren (siehe Schema). Unter Verwendung dieses Additivs sind Salzkristalle mit zwei Morphologien separat erhältlich, darunter auch rhombisch-dodekaedrische NaCl-Kristalle. Im Unterschied zu anderen Additiven wie Glycin genügt schon die Zugabe von Spuren an Barbitursäure.

Effect of Particle Size Distribution on Microstructure and Wettability of 316L Coating

In this paper, a superhydrophobic surface was first obtained on plasma sprayed 316L coatings. The influence of particle size distribution of feedstock powder on the microstructure of the prepared coating was investigated. The results show that a wide particle size distribution may lead to a porous coating with a micro/submicro dual scale morphology. The wettability of the porous coating can change from superhydrophilicity to superhydrophobicity through modulating the surface energy. In addition, mechanical durability tests show that the morphology of the prepared coating varies periodically with abrasion time. The successive exposing of fresh layers with similar morphology during abrasion process was proposed to explain this phenomenon.

Aspects of second-language transfer in the oral production of Egyptian and Palestinian heritage speakers

The nature and extent of the impact of language transfer in majority–minority language contexts have been widely debated in both second- and heritage-language acquisition. This study examines four linguistic areas in three oral narratives collected from Egyptian and Palestinian heritage speakers in the United States (namely, plural and dual morphology, possessive constructions, and restrictive relative clauses), with a special focus on how the second language (English) influences the structure and use of these areas in connected discourse. In addition, the study examines the relationship between second-language transfer and the incompleteness and attrition of heritage Arabic. The findings show that heritage speakers have various gaps in their knowledge of the examined areas, particularly in forms and patterns that diverge from their counterparts in their dominant L2. The results also suggest that transfer effects are restricted to specific forms that are marked (e.g. broken plurals), infrequent (duals), or characterized by processing difficulty (as seems to be the case with the dependencies in the relative clauses). Moreover, transfer effects are intimately related to both the attrition and incomplete acquisition of the speakers’ knowledge of the four areas under study. The implications of the study for heritage language research are discussed.

Water-repellent coatings prepared by modification of ZnO nanoparticles

Superhydrophobic coatings with a static water contact angle (WCA)>150° were prepared by modifying ZnO nanoparticles with stearic acid (ZnO@SA). ZnO nanoparticles of size ∼14nm were prepared by solution combustion method. X-ray diffraction (XRD) studies reveal that as prepared ZnO has hexagonal wurtzite structure whereas the modified coatings convert to zinc stearate. Field emission scanning electron micrographs (FE-SEM) show the dual morphology of the coatings exhibiting both particles and flakes. The flakes are highly fluffy in nature with voids and nanopores. Fourier transformed infrared (FTIR) spectrum shows the stearate ion co-ordinates with Zn2+ in the bidentate form. The surface properties such as surface free energy (γp) and work of adhesion (W) of the unmodified and modified ZnO coatings have been evaluated. The electron paramagnetic resonance (EPR) spectroscopy reveals that surface defects play a major role in the wetting behavior.

Cobalt oxide polymorph growth on electrostatic self-assembled nanoparticle arrays fordually tunable nano-textures

We report on a method for surface nano-texturing on a plastic substrate. Nano-objectswith a silica nanoparticle core and a textured cobalt oxide crown are created withselectable density on the plastic substrate. The resulting dual morphology is easily tunedover large areas, either by changing the parameters directing nanoparticle depositionthrough electrostatic self-arrangement for nano-object density control, or the parameterdirecting cobalt oxide deposition for shape control. The entire process takes place at roomtemperature, with no chemicals harmful to the plastic substrate. The ready modulation ofthe dual morphology is used to control the wettability properties of the plastic film, whichis covered by nano-objects.

The Effect of Large Reduction on the Microstructure and Properties for As-Hot Rolled Dual-Phase Nb-Bearing Steel

The effect of reduction on the microstructure refinement and mechanical properties of the as-hot rolled dual-phase Nb-bearing steel were studied at laboratory. It is found that the dual-phase steel displays clearly classic dual phase morphology which is ferrite and martensite or bainsite, and the fine island or lath martinsite is dispersed on the matrix of ferrite by the observation of microstructure. The grain can be refined, and the increased precipitated second particles are fined and dispersed with the increasing of reduction. The mechanical properties determination result shows that the mechanical properties have greatly improved by large reduction. The tensile strength obtained in the laboratory is up to 680MPa, the ratio of yield strength and tensile strength is low, and the elongation is better.

Property tailoring of phenol–formaldehyde matrices by control of reactant molar ratio and thermoplastic modification

AbstractHigh modulus, strength and thermal stability make phenol–formaldehyde resins (PFRs) interesting as matrices for nanocomposites. Four PFR matrices synthesized with different formaldehyde (F) to phenol (P) molar ratios were investigated, as well as the influence of thermoplastic modification on their mechanical properties. The effectiveness of a specific curing cycle for obtaining macrovoid‐ and microvoid‐free specimens by controlling the thickness of samples is demonstrated. Fourier transform infrared spectroscopy results reveal that F content increases the presence of oxidized linkages as benzophenones and fully substituted aromatic structures. PFR matrices with highest F content present the highest values of main transition temperature and flexural modulus up to an F/P ratio of 1.8, revealing the achievement of a densely crosslinked and rigid structure. A selected PFR matrix was modified with 5, 10 and 15 wt% of two poly(vinyl butyral) (PVB) thermoplastics of differing molecular weight. Phase separation occurs before gelation in all cases leading to different morphologies, observed using atomic force microscopy and optical microscopy, depending on PVB content: PVB‐rich particles in PFR‐rich matrix for 5 wt% and co‐continuous dual morphology for 10 and 15 wt% for both PVBs. Strength improvement is achieved for PFR matrices modified with 5 wt% of PVB associated with a tailored particulate morphology with a particle size of around 1.2 µm. Finally, 5 and 10 wt% PVB‐modified PFR materials exhibit a very high thermal stability with degradation temperatures very close to those for neat PFR matrix. Copyright © 2011 Society of Chemical Industry

Dual morphology scoring system as predictor of blast thaw pregnancy outcome

Dual morphology scoring system as predictor of blast thaw pregnancy outcome

Solidification microstructures and mechanical properties of high-vanadium Fe–C–V and Fe–C–V–Si alloys

Fe–C–V and Fe–C–V–Si alloys of various C, V and Si compositions were investigated in this work. It was found that the phases present in both of these alloy systems were alloyed ferrite, alloyed cementite, and VC x carbides. Depending on the alloy composition the solidified microstructural constituents were granular pearlite-like, lamellar pearlite, or mixtures of alloyed ferrite + granular pearlite-like or granular pearlite-like + lamellar pearlite. In addition, it is shown that in Fe–C–V alloys the C/V ratio influences (a) the type of matrix, (b) the fraction of vanadium carbides, f v and (c) the eutectic cell count, N F. In Fe–C–V alloys, a relationship between the alloy content corresponding to the eutectic line was experimentally determined and can be described by C e = 7.91 V e − 0.635 where C e and V e are the carbon and vanadium composition of the eutectic. Moreover, in the Fe–C–V alloys (depending on the alloy chemistry), the primary VC x carbides crystallize with non-faceted or non-faceted/faceted interfaces, while the eutectic morphology is non-faceted/non-faceted with regular fiber-like structures, or it possesses a dual morphology (non-faceted/non-faceted with regular fiber-like structures + non-faceted/faceted with complex regular structures). In the Fe–C–V–Si system, the primary VC x carbides solidify with a non-faceted/faceted interface, while the eutectic is non-faceted/faceted with complex regular structures. In particular, spiral eutectic growth is observed when Si is present in the Fe–C–V alloys. In general, it is found that as the matrix constituent shifts from predominantly ferrite to lamellar pearlite, the hardness, yield and tensile strengths exhibit substantial increases at expenses of ductility. Moreover, Si additions lead to alloy strengthening by solid solution hardening of the ferrite phase and/or through a reduction in the eutectic fiber spacings with a decrease in the alloy ductility.

Photo Polymerized Interpenetrating Polymer Network of Poly(antimony acrylate) and Poly(arsenic acrylate): Synthesis and Characterization

A series of IPN based on poly(antimony acrylate) and poly(arsenic acrylate) have been synthesized by a sequential mode of synthesis. Formation of complex based on “polymer solvent” method reflects the contraction of the polymer coils by determining the value of mutual interaction constant (kAB) in different solvents such as dimethylsulphoxide (DMSO) (kAB=0.60); dimethylformamide (DMF) (kAB=0.42); dioxane (kAB=0.26) predicting weak Vander Waal interaction. The scanning electron microscopy reveals dual phase morphology of both metal acrylates. The infrared spectrum indicates characteristic frequencies of (>C˭O) at 1730 cm−1,thus giving structural evidence for IPN. The properties namely percentage swelling, average molecular weight between crosslinks(Mc),Young's modulus, increases with concentrations of linear polymer(polyantimony acrylate) and initiator (benzoyl peroxide). However, it decreases with concentrations of monomer (arsenic acrylate) and crosslinker (divinyl benzene).The value of activation energy calculated from thermo gravimetric analysis is 15 KJ/mol.

Dual Morphology of Islands and Fractal Holes in Block Copolymer Thin Films

This work was funded in part by the National Research Laboratory program. Financial supports from the Korean Ministry of Education through the Brain Korea 21 Program and from the Korean Ministry of Science and Technology (MOST) under Grant 99-07 as well as through the National Program for Tera-level Nano-devices as one of the 21 century Frontier Programs are also greatly appreciated. SAXS experiments performed at PLS were supported in part by MOST and POSCO. We thank Dr. S.-H. Chu for helping us with the ellipsometry.

Coronary artery disease in the transplanted heart.

Coronary artery disease in the transplanted heart limits the long-term success of cardiac transplantation. Intravascular ultrasound studies reveal a dual morphology with donor-transmitted and de novo plaques. Coronary vasomotor dysfunction may occur independently of morphological alterations. The disease is characterized by the interaction of activated T lymphocytes with cytokines and donor epicardial and microvascular endothelium. Various noxious stimuli contribute to the continuing inflammatory response. Consequently, adhesion molecule expression is upregulated, leukocytes migrate into the allograft, thrombocytes accumulate, and growth factors are expressed, finally resulting in functional and morphological chronic allograft lesions. Blocking the activation of T cells, CD4+ cytokines, and adhesion molecules may prevent endothelial injury and subsequent intimal thickening. Strategies to decrease the formation of anti-endothelial and anti-HLA-DR antibodies may also be protective, as may antiproliferative drugs, augmentation of endogenous nitric oxide bioactivity, and new immunosuppressive regimens. Revascularization procedures have a limited role in treating significant focal lesions. Retransplantation, the only definitive treatment, remains ethically controversial.

Dual morphology and topography of the corticothalamic terminals originating from the primary, supplementary motor, and dorsal premotor cortical areas in macaque monkeys.

In the motor, somatosensory, and auditory systems of rodents and cats, the corticothalamic connection is composed of a main projection formed by small endings and a minor projection terminating with giant endings. To establish whether the corticothalamic projection originating from motor cortical areas in primates exhibits the same duality, the anterograde tracer biotinylated dextran amine was injected in eight macaque monkeys in the primary motor (M1; n = 3), the supplementary motor (SMA; n = 3) and the dorsal premotor (PMd; n = 2) cortical areas to label corticothalamic axons. The corticothalamic projection originating from these three motor cortical areas was characterized by the presence of axon terminals constituting the same two types of endings, observed both as boutons en passant and terminaux. The population of small endings exhibited a mean cross-sectional maximum diameter of 0.95 microm (S.D. = 0.23), a range of diameters not overlapping that of giant endings (mean diameter = 3.46 microm, S.D. = 0.74 microm). Topographically, the giant endings originating from M1 were located in the same thalamic nucleus (ventroposterolateral nucleus, oral part) in which the small endings were found. In contrast, the giant endings originating from SMA and PMd were located in a thalamic nucleus (mediodorsal nucleus) distinct from the main termination zone formed by small endings. Along the rostrocaudal axis, the giant endings were distributed in a restricted zone, irrespective of the origin of the projection (M1, SMA, PMd). The dual morphology of corticothalamic endings, previously found in rodents and cats, is present in the motor system of subhuman primates for both primary and nonprimary motor cortical areas.

Cardiac Allograft Vasculopathy

Cardiac allograft vasculopathy (CAV) remains a troublesome long-term complication of heart transplantation. It is manifested by a unique and unusually accelerated form of coronary disease affecting both intramural and epicardial coronary arteries and veins.CAV is characterized by vascular injury induced by a variety of noxious stimuli, including the immune system response to the allograft, ischemia-reperfusion injury, viral infection, immunosuppressive drugs, and classic risk factors such as hyperlipidemia, insulin resistance, and hypertension. The obstructive vascular lesions are thought to progress through repetitive endothelial injury followed by repair response. The role of major histocompatibility complex donor-recipient differences in the pathogenesis of CAV has not yet been completely elucidated. Intracoronary ultrasound studies reveal a dual morphology with donor-transmitted or de novo focal, noncircumferential plaques in proximal segments and/or a diffuse, concentric pattern observed in distal segments. A lack of correlation between microvascular and epicardial vessel disease suggests discordant manifestations and progression of CAV. Apoptosis and loss of functional vascular remodeling have to be considered as important mediators of clinically relevant CAV. Strategies for blocking T-cell costimulation and expression of adhesion molecules may help prevent chronic rejection in clinical transplantation. 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors and antiproliferative drugs may slow progression of CAV by various effects. Methods to augment endogenous nitric oxide bioavailability as well as newer immunosuppressive regimens may be protective. Balloon angioplasty has a limited role in the treatment of focal lesions. Experiences with coronary stenting, coronary artery bypass grafting, and transmyocardial laser revascularization are limited. Retransplantation has a worse outcome than initial transplantation.

Deformation resistance in oriented nylon 6

Initially spherulitic nylon 6 was textured into a quasi-single crystal form by plane-strain compression in deep channel-die, followed by cooling under pressure to room temperature. The resulting material, having orthotropic symmetry with quasi-single crystalline perfection, had a dual morphology in which the normals of the crystallographic (100) planes equipartition at ±20° with respect tot he constraint direction of the planne-strain deformation. This highly textured material, has relatively large dimensions in all directions, was used to study the elastic and plastic anisotropy of the actual constituent lamellar crystallites

The dopaminergic amacrine cell

The detailed morphology of the dopaminergic amacrine cell type has been characterized in the macaque monkey retina by intracellular injection of horseradish peroxidase (HRP). This cell type was recognized by its large soma in an in vitro, wholemount preparation of the retina stained with the fluorescent dye, acridine orange. HRP-fills revealed a large, sparsely branching, spiny dendritic tree and a number of extremely thin, axon-like processes that arose from the soma and proximal dendrites. The axon-like processes were studded with distinct varicosities and were traced for up to 3 mm beyond the dendritic tree. The true lengths of the axon-like processes were greater than 3 mm, however, because the HRP reaction product consistently diminished before an endpoint was reached. Both the dendrites and the axon-like processes were narrowly stratified close to the outer border of the inner plexiform layer, although in a few cases single axon-like processes projected into the outer nuclear and outer plexiform layers. The HRP-filled amacrines appeared equivalent to a subpopulation of neurons that are intensely immunoreactive for tyrosine hydroxylase (TH). TH-immunoreactive cells showed a nearly identical soma size and dendritic field size range, the same pattern of dendritic branching and spiny morphology, and also gave rise to distinct axon-like processes from both the soma and proximal dendrites. To test this correspondence more directly, the large acridine stained cells were injected with Lucifer Yellow and the retina was subsequently processed for TH immunoreactivity using diaminobenzidine as the chromagen. In all cases Lucifer Yellow injected cells also showed intense TH immunoreactivity. Spatial densities of the TH amacrine cells were therefore used to calculate coverage factors for the dendritic trees and for the axon-like components of the HRP-filled cells. The axon-like processes showed a coverage factor of at least 300, about 100 times that of the dendritic fields. This great overlap could be directly observed in TH-immunoreacted retinal wholemounts as a dense plexus of fine, varicose processes. The density of the TH plexus is greater than the density predicted from the lengths (1-3 mm) of the HRP-filled axon-like processes however, and suggests that the axon-like processes have an actual length of about 4-5 mm.(ABSTRACT TRUNCATED AT 400 WORDS)