Symmetric Morphology Research Articles

Confined Magnetic-Dielectric Balance Boosted Electromagnetic Wave Absorption.

Magnetic-dielectric property plays a critical significance for the functional expression toward advanced materials. Within nanoscale, the simultaneous regulation of the electrical and magnetic properties of electromagnetic (EM) wave absorption materials faces huge challenges. Herein, using the metal-organic frameworks (MOF) as templates, highly-dispersed ZnO and Co nanoparticles are uniformly confined inside graphited N-doped carbon skeleton, constructing the balanced EM property in the Co@NC-ZnO absorbers. Meanwhile, a dynamics and symmetrical morphology optimization of MOF-derived Co@NC-ZnO are dependent on the Co/Zn mass ratio and adjusting MOF frameworks, which evolves from the cube, truncated cube, dodecahedron, and to the final microsphere. Simultaneously, both the electronic conduction network and magnetic coupling network are compatible together in the in situ transformed Co@NC-ZnO system. Boosted magnetic responding ability and unique magnetic coupling are verified by the off-axis electronic holography. Plentiful heterojunction interfaces and special electronic conduction paths can be built in this Co-Zn-MOF derivatives, facilitating the dielectric loss behaviors. As expected, MOF-derived Co@NC-ZnO absorber displays outstanding EM wave absorption ability with strongest reflection loss value of -69.6 dB at only 1.9 mm thickness and wideband absorption covering 6.8 GHz at 2.4 mm. Confined EM balance provides new design strategy toward MOF-derived excellent MA materials and functional devices.

Seasonal changes and migration of longitudinal dunes in the northeastern Rub'al Khali Desert

The morphology of small longitudinal dunes responded clearly to wind fields in the northeastern Rub'al Khali Desert. Based on local meteorological data and high-resolution satellite images, we analyzed the wind regime, drift potential (DP), dune morphology changes, and migration rates. The wind roses revealed that two opposing winds (from the northwest and southeast), both at an oblique angle to the dune crest, dominated the structure of the wind regime, with periodic changes between these directions. The annual DP from 2017 to 2019 ranged from 615 to 688 vector units (VU), and the resultant drift potential (RDP) ranged from 149 to 311 VU, indicating a high-energy wind environment. The most erosive winds (DP > 60 VU) occurred from February to June. Controlled by the wind field, dune morphology remained longitudinal from September to May. However, small longitudinal dunes (height below 5 m) transformed into transverse dunes from June to August, and formed a dune network with the large longitudinal dunes. On flat land, a series of active longitudinal dunes migrated at 7.8 to 15.1 m yr−1, with a mean of 11.9 m yr−1. Their dominant migration mode was parallel to the resultant drift direction (RDD), with the dunes extending downwind via accretion at the downwind ends. These dunes also migrate laterally by 0.4 to 0.8 m yr−1 while maintaining a symmetrical longitudinal dune morphology. These results expand our knowledge of dune migration and evolution, and provide guidance for protecting areas such as oases threatened by migrating dunes.

Asymmetric instability in thin-film flow down a fiber

Experiments show that thin film flow down a fiber exhibits beading patterns whose symmetry about the fiber depends upon the fiber diameter and liquid surface tension. Both symmetric and asymmetric morphologies exhibit absolute (isolated, Plateau-Rayleigh) and convective instabilities, with the asymmetric beading dynamics resembling that of the free viscous jet indicating a minimal interaction between the liquid and fiber.

Characteristics of the Galactic Center excess measured with 11 years of Fermi -LAT data

The excess of $\gamma$ rays in the data measured by Fermi-LAT from the Galactic center region is one of the most intriguing mysteries in Astroparticle Physics. This Galactic center excess (GCE), has been measured with respect to different interstellar emission models (IEMs), source catalogs, data selections and techniques. Although several proposed interpretations have appeared in the literature, there are not firm conclusions as to its origin. The main difficulty in solving this puzzle lies in modeling a region of such complexity and thus precisely measuring the characteristics of the GCE. In this paper, we use 11 years of Fermi-LAT data, state of the art IEMs, and the newest 4FGL source catalog to provide precise measurements of the energy spectrum, spatial morphology, position, and sphericity of the GCE. We find that the GCE has a spectrum which is peaked at a few GeV and is well fit with a log-parabola. The normalization of the spectrum changes by roughly $60\%$ when using different IEMs, data selections and analysis techniques. The spatial distribution of the GCE is compatible with a dark matter (DM) template produced with a generalized NFW density profile with slope $\gamma = 1.2-1.3$. No energy evolution is measured for the GCE morphology between $0.6-30$ GeV at a level larger than $10\%$ of the $\gamma$ average value, which is 1.25. The analysis of the GCE modeled with a DM template divided into quadrants shows that the spectrum and spatial morphology of the GCE is similar in different regions around the Galactic center. Finally, the GCE centroid is compatible with the Galactic center, with best-fit position between $l=[-0.3^{\circ},0.0^{\circ}],b=[-0.1^{\circ},0.0^{\circ}]$, and it is compatible with a spherical symmetric morphology. In particular, fitting the DM spatial profile with an ellipsoid gives a major-to-minor axis ratio between 0.8-1.2.

Long-Range Surface-Assisted Molecule-Molecule Hybridization.

Metalated phthalocyanines (Pc's) are robust and versatile molecular complexes, whose properties can be tuned by changing their functional groups and central metal atom. The electronic structure of magnesium Pc (MgPc)-structurally and electronically similar to chlorophyll-adsorbed on the Ag(100) surface is investigated by low-temperature scanning tunneling microscopy and spectroscopy, non-contact atomic force microscopy, and density functional theory. Single, isolated MgPc's exhibit a flat, fourfold rotationally symmetric morphology, with doubly degenerate, partially populated (due to surface-to-molecule electron transfer) lowest unoccupied molecular orbitals (LUMOs). In contrast, MgPc's with neighbouring molecules in proximity undergo a lift of LUMOs degeneracy, with a near-Fermi local density of states with reduced twofold rotational symmetry, indicative of a long-range attractive intermolecular interaction. The latter is assigned to a surface-mediated two-step electronic hybridization process. First, LUMOs interact with Ag(100) conduction electrons, forming hybrid molecule-surface orbitals with enhanced spatial extension. Then, these delocalized molecule-surface states further hybridize with those of neighbouring molecules. This work highlights how the electronic structure of molecular adsorbates-including orbital degeneracies and symmetries-can be significantly altered via surface-mediated intermolecular hybridization, over extended distances (beyond 3nm), having important implications for prospects of molecule-based solid-state technologies.

Study of the Growth Mechanism of Solution-Synthesized Symmetric Tellurium Nanoflakes at Atomic Resolution.

As a new member of 2D materials, 2D tellurium (Te) has recently attracted much attention due to its intriguing properties. Through hydrothermal processing, 2D Te with tunable thickness and size has been realized, and its growth mechanism has also been studied. However, the tailored growth of 2D Te nanoflakes with symmetrical morphologies and interfacial moiré fringes has never been reported. Here, 2D Te nanoflakes have been prepared using the hydrothermal method, and mirror-symmetrical shapes (including "V-shape," "heart-shape," and "paper airplane-shape") with obvious moiré fringes in the middle of the nanoflakes are observed. Comprehensive transmission electron microscopy (TEM) techniques are utilized for structural characterization of these nanoflakes, especially the moiré fringes in the symmetry axis region of the nanoflakes. The systematic analyses of the moiré fringes and the observation of obvious overlapping edges of the composing nanoflakes from the cross-sectional samples reveal the possible mechanism of morphological evolution for these symmetrical nanoflakes. These details may fill the research gap in the controllable growth of 2D Te nanomaterials, pave the way for the fabrication of 2D Te moiré superlattices and in-plane homojunctions, and promote their future versatile applications.

The Flat Rotation Curve of the Spiral Galaxies may be the Result of the Perfect Combination of the Fluid Mechanics and the Gravitational Mechanics

A new hypothesis is proposed to explain the flat rotation curve of the spiral galaxies. The spiral galaxies can be treated as ideal fluid systems. For Milky Way, the mass density is constant within the radius of 0.65 kpc in the central portion of the bugle and results the linear relationship between the rotation velocity and the distance to the galactic center. The rotation of the spiral galaxies is driven by the central galactic bars and follows both fluid mechanics and gravitational mechanics, the flat rotation curve of the spiral galaxies is the result of the perfect combination of the fluid mechanics and the gravitational mechanics, the nature has balanced itself very well, the mass density distribution indirectly extracted from NASA’s near-infrared image of the Milky Way seems matching the hypothesis. Therefore, the “dark matter” could be unnecessary for the purpose of adding additional gravitational matter, but this does not deny the possible existence of the proposed dark matter in the universe. The feature of the flat rotation curve could be established during the formation of the galaxies from vast clouds of gas and dust, then, is maintained by gravitational force among those celestial objects, gases and interstellar medium, and such gravitational force acts as a binding force and fluid viscosity. After galactic merging, the combination of the fluid mechanics and gravitational mechanics is the only way to restore the galaxies into nice symmetric disk-like morphology with flat feature of the rotation curve after enough evolution time. The super black holes in the centers of the galaxies could be the rotation engines for whole rotation of galaxies. This model may not be perfect and could be improved in the future.

A Dust Trap in the Young Multiple System HD 34700

Abstract Millimeter observations of disks around young stars reveal substructures indicative of gas pressure traps that may aid grain growth and planet formation. We present Submillimeter Array observations of HD 34700: two Herbig Ae stars in a close binary system (Aa/Ab, ∼0.25 au), surrounded by a disk presenting a large cavity and spiral arms seen in scattered light, and two distant, lower-mass companions. These observations include 1.3 mm continuum emission and the 12CO 2–1 line at ∼05 (178 au) resolution. They resolve a prominent azimuthal asymmetry in the continuum and Keplerian rotation of a circumbinary disk in the 12CO line. The asymmetry is located at a radius of 155+11 −7 au, consistent with the edge of the scattered-light cavity, being resolved in both radius (72 +14 −15 au) and azimuth (FWHM = 64°+8 −7). The strong asymmetry in millimeter continuum emission could be evidence for a dust trap, together with the more symmetric morphology of 12CO emission and small grains. We hypothesize an unseen circumbinary companion responsible for the cavity in scattered light and creating a vortex at the cavity edge that manifests in dust trapping. The disk mass has limitations imposed by the detection of 12CO and nondetection of 13CO. We discuss its consequences for the potential past gravitational instability of this system, likely accounting for the rapid formation of a circumbinary companion. We also report the discovery of resolved continuum emission associated with HD 34700B (projected separation ∼1850 au), which we explain through a circumstellar disk.

LeMMINGs – II. The e-MERLIN legacy survey of nearby galaxies. The deepest radio view of the Palomar sample on parsec scale

ABSTRACT We present the second data release of high-resolution (≤0.2 arcsec) 1.5-GHz radio images of 177 nearby galaxies from the Palomar sample, observed with the e-MERLIN array, as part of the Legacy e-MERLIN Multi-band Imaging of Nearby Galaxies Sample (LeMMINGs) survey. Together with the 103 targets of the first LeMMINGs data release, this represents a complete sample of 280 local active (LINER and Seyfert) and inactive galaxies (H ii galaxies and absorption line galaxies, ALG). This large program is the deepest radio survey of the local Universe, ≳1017.6 W Hz−1, regardless of the host and nuclear type: we detect radio emission ≳0.25 mJy beam−1 for 125/280 galaxies (44.6 per cent) with sizes of typically ≲100 pc. Of those 125, 106 targets show a core which coincides within 1.2 arcsec with the optical nucleus. Although we observed mostly cores, around one third of the detected galaxies features jetted morphologies. The detected radio core luminosities of the sample range between ∼1034 and 1040 erg s−1. LINERs and Seyferts are the most luminous sources, whereas H ii galaxies are the least. LINERs show FR I-like core-brightened radio structures while Seyferts reveal the highest fraction of symmetric morphologies. The majority of H ii galaxies have single radio core or complex extended structures, which probably conceal a nuclear starburst and/or a weak active nucleus (seven of them show clear jets). ALGs, which are typically found in evolved ellipticals, although the least numerous, exhibit on average the most luminous radio structures, similar to LINERs.

Orbitofrontal Reconstruction With a Three-Dimensional Titanium Patient-Specific Implant After Intraosseous Haemangioma Resection

Intraosseous hemangiomas are rare benign tumors that can develop in the skull. Orbitofrontal localization is uncommon. The complexity of orbitofrontal anatomy results in difficult reconstruction following trauma or tumoral resection. A 50-year-old woman with a right orbitofrontal intraosseous hemangioma was referred to our department. The authors decided to perform tumoral bone resection and orbitofrontal reconstruction using virtual surgical planning in collaboration with Materialize engineers (Materialise, Leuven, Belgium). Three cutting guides and a patient-specific 3-dimensional (3D) titanium implant were designed and manufactured in 3 weeks. Surgery was performed with a double surgical team composed of maxillofacial surgeons and neurosurgeons. No perioperative or post-operative complications occurred. Post-operatively, the patient was completely asymptomatic and clinical examination showed symmetrical and satisfactory facial morphology. Virtual surgical planning, design of patient-specific guides and manufacturing of implants make surgery easier and increase surgical precision. This technique is recommended for wide use in cases of oncological or complex trauma craniomaxillofacial reconstruction.

Hidden AGNs in Dwarf Galaxies Revealed by MaNGA: Light Echoes, Off-nuclear Wanderers, and a New Broad-line AGN

Abstract Active galactic nuclei (AGNs) in dwarf galaxies could host the relics of those early universe seed black holes that did not grow into supermassive black holes. Using MaNGA integral field unit (IFU) spectroscopy we have found a sample of 37 dwarf galaxies that show AGN ionization signatures in spatially resolved emission line diagnostic diagrams. The AGN signatures are largely missed by integrated emission line diagnostics for 23 of them. The bolometric luminosity of these 23 new AGN candidates is ≲1040 erg s−1, fainter than that of single-fiber SDSS AGNs, X-ray AGNs, and radio AGNs in dwarf galaxies, which supports IFU spectroscopy as a powerful tool for identifying hidden and faint AGNs in dwarf galaxies. The AGN emission is in most cases offset from the optical center of the dwarf galaxy and shows a symmetric morphology, which indicates that either the AGNs are off-nuclear, that the central emission of the galaxy is dominated by star formation, or that the AGNs are turned off and we are observing a past ionization burst. One of the new AGNs shows a broad Hα emission line component, from which we derive a black hole mass in the realm of intermediate-mass black holes. This constitutes the first hidden type 1 AGN discovered in a dwarf galaxy based on IFU spectroscopy. The finding of this sample of hidden and faint AGNs has important implications for population studies of AGNs in dwarf galaxies and for seed black hole formation models.

Au@Ag Core\u2013Shell Nanorods Support Plasmonic Fano Resonances

In this work, we investigated experimentally and theoretically the plasmonic Fano resonances (FRs) exhibited by core–shell nanorods composed of a gold core and a silver shell (Au@Ag NRs). The colloidal synthesis of these Au@Ag NRs produces nanostructures with rich plasmonic features, of which two different FRs are particularly interesting. The FR with spectral location at higher energies (3.7 eV) originates from the interaction between a plasmonic mode of the nanoparticle and the interband transitions of Au. In contrast, the tunable FR at lower energies (2.92–2.75 eV) is ascribed to the interaction between the dominant transversal LSPR mode of the Ag shell and the transversal plasmon mode of the Au@Ag nanostructure. The unique symmetrical morphology and FRs of these Au@Ag NRs make them promising candidates for plasmonic sensors and metamaterials components.

Identification, investigation and classification of surface depressions and chalk dissolution features using integrated LiDAR and geophysical methods

The chalk bedrock of the Hampshire Basin, southern England is an important aquifer and is highly susceptible to dissolution, making the development and presence of karstic features a widespread occurrence. These features are hazardous because they provide possible pathways to the underlying aquifer and therefore present potential site-specific contamination risks. There is also evidence of extensive extraction, through both mining and surface quarrying, of chalk, flint and clay over many centuries. Geophysical techniques consisting of electromagnetic (EM31) and ground-penetrating radar surveys were used to identify and characterize target features identified from desk study data. The ground-penetrating radar and EM31 interpretations allowed the classification of non-anthropogenic target features, such as diffuse buried sinkholes with disturbed and subsiding clay-rich infill and varying symmetrical and asymmetrical morphologies. We describe here the investigations of such features identified at Holme Farm, Stansted House, Hampshire. The combination of EM31 data and ground-penetrating radar profiles facilitated the identification of a palaeovalley, cavities and irregular rockhead. This investigation identified locations of aquifer contamination risk as some sinkholes have been sites for the illegal dumping of waste or the infiltration of fertilizers, leaking sewage pipes or animal waste. This potential source of contamination utilizes the sinkhole as a pathway into the highly transmissive White Chalk Subgroup of Hampshire and has caused contamination of the aquifer. We conclude that our integrated approach of geophysical techniques linked to aerial photographs and LiDAR image interpretation was highly effective in the location and characterization of dissolution structures, infilled former quarries and mining features at this site.

Isomerism of the atrial appendages: morphology and terminology.

Our aim is to identify the pathognomonic anatomical markers and the best terminology to describe the cardiac malformations associated with absent or multiple spleens, which are known as asplenia or polysplenia syndromes or isomerism. We have reviewed 65 hearts with isomerism of atrial appendages of the Anatomical Collections of Congenital Heart Disease, Institute of Pathological Anatomy of the University of Padua consisting of 1800 specimens. All the hearts were classified according to sequential segmental classification. The incidence of isomerism was 3.6%. Of the total, 45 hearts with isomerism of right atrial appendages showed bilateral trilobed lungs, short bronchi, and absent spleen. The atrioventricular junction was univentricular in 49% of cases with a common atrioventricular valve in 91%. Pulmonary atresia and double outlet right ventricle were present in 40% and 47% of cases, respectively. Total anomalous pulmonary venous drainage and absent coronary sinus were always present. In 20 hearts with isomerism of left atrial appendages, bilateral bilobed lungs with long bilateral bronchi and multiple spleens were always found. The biventricular atrioventricular connection was present in 65% with a common valve in 30% of the hearts. The ventriculoarterial connection was concordant in 45% of cases, and aortic atresia and pulmonary atresia were both noted in 15% of each. An anomalous symmetric pulmonary venous drainage was observed in 65% of the hearts and interruption of inferior vena cava was found in 75% of cases. We believe that the appropriate terminology is based on the symmetrical morphology of the atrial appendages. The absence of the coronary sinus and the total anomalous pulmonary venous drainage are the markers of isomerism of the right atrial appendages. Symmetric pulmonary venous drainage and interruption of inferior vena cava are the markers of isomerism of left atrial appendages. In recent years, thanks to the improvement of clinical diagnosis and of surgical techniques these patients have the possibility to survive to adult age.

Self-assembly of Janus Au:Fe3O4 branched nanoparticles. From organized clusters to stimuli-responsive nanogel suprastructures.

Janus nanoparticles offer enormous possibilities through a binary selective functionalization and dual properties. Their self-assembly has attracted strong interest due to their potential as building blocks to obtain molecular colloids, supracrystals and well-organized nanostructures that can lead to new functionalities. However, this self-assembly has been focused on relatively simple symmetrical morphologies, while for complex nanostructures this process has been unexplored. Here, we study the assembly of plasmonic-magnetic Janus nanoparticles with a branched (nanostar) – sphere morphology. The branched morphology enhances their plasmonic properties in the near-infrared region and therefore their applicability, but at the same time constrains their self-assembly capabilities to obtain more organized or functional suprastructures. We describe the self-assembly of these nanoparticles after amphiphilic functionalization. The role of the nanoparticle branching, as well as the size of the polymer-coating, is explored. We show how the use of large molecular weight stabilizing polymers can overcome the anisotropy of the nanoparticles producing a change in the morphology from small clusters to larger quasi-cylindrical nanostructures. Finally, the Janus nanoparticles are functionalized with a thermo-responsive elastin-like recombinamer. These nanoparticles undergo reversible self-assembly in the presence of free polymer giving rise to nanoparticle-stabilized nanogel-like structures with controlled size, providing the possibility to expand their applicability to multi-stimuli controlled self-assembly.

Fluorescent mouse pheochromocytoma spheroids expressing hypoxia-inducible factor 2 alpha: Morphologic and radiopharmacologic characterization

BACKGROUND:Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-producing tumors arising from chromaffin tissue. In a PPGL subgroup, dysregulation of hypoxia signaling pathways, in particular mediated through stabilization of hypoxia-inducible factor 2 alpha (HIF2α), have been sugges ted to drive tumorigenesis through altering downstream transcriptional activity. OBJECTIVE:This study evaluated the use of mCherry-transgenic mouse pheochromocytoma (MPCmCherry) spheroids as in vitro models for investigating consequences of HIF2α expression on aggregation behavior, morphology, growth, glucose consumption, amino acid uptake, and somatostatin type 2 receptors under stable hypoxic conditions. METHODS:MPCmCherry spheroids were monitored using confocal laser scanning microscopy. Hypoxic regions were detected using pimonidazole. Radiotracer incubation was performed using 2-[18F]fluoro-2-deoxyglucose ([18F]FDG), O-3-(2[18F]fluoroethoxy)-4-hydroxyphenylalanine ([18F]OFED), and [68Ga]Ga-(Tyr3)octreotate ([68Ga]Ga-DOTA-TATE). RESULTS:Both HIF2α-expressing and empty vector (EV) control spheroids showed regions of stable cellular hypoxia. Expression of HIF2α in MPCmCherry spheroids was associated with less symmetric morphology, faster growth, and decreased uptake of [68Ga]Ga-DOTA-TATE (somatostatin type 2 receptors) compared to controls, whereas, uptake of [18F]FDG (glucose transporter 1 and hexokinases) and [18F]OFED (system L amino acid transporter 1) remained unaffected. CONCLUSIONS:The recent study proved MPCmCherry spheroids to be complex three-dimensional tumor cell models for investigating morphologic and metabolic consequences of dysregulated hypoxia pathways under hypoxic conditions.

Formation Mechanisms of Exit-Chippings in Rotary Ultrasonic Drilling and Conventional Drilling of Glass BK7

Abstract This paper presented a fundamental investigation on the exit-chipping formation mechanisms involved in rotary ultrasonic drilling (RUD) and conventional drilling (CD) of glass BK7. It was found that the mutual tool-material extrusion initially activated the subsurface crack with the maximum depth (incipient crack) at the margin of the machined surface, and its penetration of the undrilled thickness brought about the emergence of the exit-chipping at Region I. Subsequently, the opposite propagations of two ring-cracks along the circumferential direction of the drilled hole were conducive to the collapse of the machined cylinder, thus leading to the appearance of the exit-chipping at Region II. Ultrasonic superposition significantly decreased the actual undrilled thickness of the machined surface, while slightly increased the exit-chipping width. All the exit-chippings, generated with and without ultrasonic, exhibited the elliptic and symmetrical morphologies accompanied by the corrugated stripes winding the entire chipping surfaces. The quantitative relationship between the instantaneous extrusion pressure and the propagation direction of the incipient crack was proposed, revealing that the propagation angle was inversely proportional to the extrusion pressure. Ultrasonic superimposition augmented the extrusion pressure exerted the machined surface, which reduced the propagation angle of the incipient crack. The elliptic morphology characteristics of the exit-chipping were attributed to the parabolic variation of the additional bending moment with the circumferential spreading of the ring-crack. Ultrasonic superposition increased the propagation angle of the ring-crack, thus deteriorating the exit quality of the drilled hole.

Asymmetrical than symmetrical cerebral arterial bifurcations are more vulnerable to aneurysm presence

In order to investigate the role of lateral angle ratio (LA ratio) and daughter artery ratio (DA ratio) for predicting aneurysmal presence in main cerebral arterial bifurcations, three-dimensional cerebral angiographic data of major cerebral artery bifurcations were used for measurement of artery diameters and bifurcation angles including 115 middle cerebral arteries (MCAs), 59 basilar arteries (BAs), 35 internal carotid arteries (ICAs) and 115 anterior cerebral arteries (ACAs) with bifurcation aneurysms and control subjects of 1921 bifurcations with no aneurysms. The LA ratio (larger lateral angle/smaller lateral angle) and DA ratio (larger branch diameter/smaller branch diameter) were calculated, and ROC curve analysis of LA and DA ratios between normal and aneurysmal cases was performed. The LA and DA ratios of MCA bifurcations and the LA ratios of BA and ICA bifurcations with aneurysms were all significantly larger than normal bifurcations (P < 0.05), and the DA ratio of ACA bifurcations with aneurysms was significantly smaller than normal cases (P < 0.01). Moreover, the LA ratio or DA ratio between the normal and aneurysm cases in MCA, BA and ACA bifurcations demonstrated significant differences by ROC analysis (P < 0.01) except in the ICA bifurcations. No significant difference was observed (P > 0.05) between ruptured and unruptured aneurysms in MCA, BA, ICA and ACA bifurcations. In summary, normal MCA, BA and ICA bifurcations show symmetrical morphology in the lateral angles and daughter branches, whereas aneurysmal bifurcations show asymmetrical morphology. Normal ACA bifurcations have asymmetrical bilateral daughter branches while symmetrical branches are associated with ACA bifurcation aneurysm presence.

Recovery of 1-ethyl-2-methylbenzene from wastewater by polymeric membranes via pervaporation process

In the present study for the first time, recovery of 1-ethyl-2-methylbenzene from aqueous solution was investigated by pervaporation process with polymeric membranes containing ethylene propylene diene monomer (EPDM), poly dimethylsiloxane (PDMS), poly vinylidenefluoride (PVDF) and poly ether-block-amide (PEBA). After preparation of membranes by solution casting method, the membranes were applied in pervaporation experiments at ambient temperature to determine several parameters such as flux, separation factor and pervaporation separation index (PSI). Scanning electron microscopy (SEM), contact angle, mechanical resistance and degree of swelling analyses were performed to characterize the prepared membranes. SEM images showed a dense and symmetrical morphology in regard to the prepared membranes. Results of contact angle analysis indicated that PDMS and EPDM membranes were completely hydrophobic in comparison with the other prepared membranes. Percent of swelling for all membranes was rather low and all of them swelled lower than 3.5%; however, swelling value for PVDF membrane was approximately negligible (0.3%). EPDM membrane with PSI value of of 653 kg/m2.h and separation factor of 3558, showed a superior performance in pervaporation process compared to the other prepared membranes; however, this membrane presented lower mechanical strength than the other membranes. PVDF membrane showed better results in terms of mechanical strength compared to the other membranes. Considering pervaporation separation index of 248 kg/m2.h and separation factor of 480, which were better than that of PDMS and PEBA membranes, PVDF showed poor performance in PV process compared with EPDM membrane. According to the higher mechanical strength and slight willingness of PVDF membrane to swelling in contact with aqueous feed, performance enhancement of this membrane in the pervaporation process can greatly surpass its position in removing 1-ethyl-2-methylbenzene from contaminated water.

Resonances in the response of fluidic networks inherent to the cooperation between elasticity and bifurcations.

A global response function (GRF) of an elastic network is introduced as a generalization of the response function (RF) of a rigid network, relating the average flow along the network with the pressure difference at its extremes. The GRF can be used to explore the frequency behaviour of a fluid confined in a tree-like symmetric elastic network in which vessels bifurcate into identical vessels. We study such dynamic response for elastic vessel networks containing viscous fluids. We find that the bifurcation structure, inherent to tree-like networks, qualitatively changes the dynamic response of a single elastic vessel, and gives resonances at certain frequencies. This implies that the average flow throughout the network could be enhanced if the pulsatile forcing at the network’s inlet were imposed at the resonant frequencies. The resonant behaviour comes from the cooperation between the bifurcation structure and the elasticity of the network, since the GRF has no resonances either for a single elastic vessel or for a rigid network. We have found that resonances shift to high frequencies as the system becomes more rigid. We have studied two different symmetric tree-like network morphologies and found that, while many features are independent of network morphology, particular details of the response are morphology dependent. Our results could have applications to some biophysical networks, for which the morphology could be approximated to a tree-like symmetric structure and a constant pressure at the outlet. The GRF for these networks is a characteristic of the system fluid-network, being independent of the dynamic flow (or pressure) at the network’s inlet. It might therefore represent a good quantity to differentiate healthy vasculatures from those with a medical condition. Our results could also be experimentally relevant in the design of networks engraved in microdevices, since the limit of the rigid case is almost impossible to attain with the materials used in microfluidics and the condition of constant pressure at the outlet is often given by the atmospheric pressure.