Spheroidal Shape Research Articles

Loss of membrane asymmetry alters the interactions of erythrocytes with engineered silica nanoparticles.

Disruption of plasma membrane integrity is a primary mechanism of nanoparticle toxicity in cells. Mechanistic studies on nanoparticle-induced membrane damage have been commonly performed using model membranes with a focus on symmetric bilayers, overlooking the fact that the membrane has an asymmetric phospholipid composition. In this study, erythrocytes with normal and scrambled membrane asymmetry were utilized to examine how the loss of membrane asymmetry and the resulting alterations in the outer leaflet lipid composition affect nanoparticle-membrane interactions. Unmodified, amine-modified, and carboxyl-modified silica (30 nm) were used as nanoparticle models. Loss of membrane asymmetry was achieved by induction of eryptosis, using a calcium ionophore. Erythrocyte membrane disruption (hemolysis) by unmodified silica nanoparticles was significantly reduced in eryptotic compared to healthy cells. Amine- and carboxyl-modified particles did not cause hemolysis in either cell. In agreement, a significant reduction in the binding of unmodified silica nanoparticles to the membrane was observed upon loss of membrane asymmetry. Unmodified silica particles also caused significant cell deformation, changing healthy erythrocytes into a spheroid shape. In agreement with findings in the cells, unmodified particles disrupted vesicles mimicking the erythrocyte outer leaflet lipid composition. The degree of disruption and nanoparticle binding to the membrane was reduced in vesicles mimicking the composition of scrambled membranes. Cryo-electron microscopy revealed the presence of lipid layers on particle surfaces, pointing to lipid adsorption as the mechanism for vesicle damage. Together, findings indicate an important role for the lipid composition of the membrane outer leaflet in nanoparticle-induced membrane damage in both vesicles and erythrocytes.

Fibroblast growth factor-4 maintains cellular viability while enhancing osteogenic differentiation of stem cell spheroids in part by regulating RUNX2 and BGLAP expression.

Fibroblast growth factors (FGFs) are growth factors that were initially identified as proteins that stimulate fibroblast proliferation. The aim of the present study was to examine the effects of FGF-4 on the morphology, cellular viability and osteogenic differentiation of stem cell spheroids. Stem cell spheroids were generated using concave microwells in the presence of FGF-4 at concentrations of 0, 50, 100 and 200 ng/ml. Cellular viability was qualitatively assessed by a fluorometric live/dead assay using a microscope and quantitatively determined by using Cell Counting Kit-8. Furthermore, alkaline phosphatase activity and calcium deposition were determined to assess osteogenic differentiation. Reverse transcription-quantitative PCR (RT-qPCR) was performed to evaluate the mRNA expression levels of Runt-related transcription factor 2 (RUNX2) and bone γ-carboxyglutamate protein (BGLAP). Spheroidal shapes were achieved in the microwells on day 1 and a significant increase in the spheroid diameter was observed in the 200 ng/ml FGF-4 group compared with the control group on day 1 (P<0.05). The results regarding viability using Cell Counting Kit-8 in the presence of FGF-4 at 50, 100 and 200 ng/ml at day 1 were 98.0±2.5, 106.2±17.6 and 99.5±6.0%, respectively, when normalized to the control group (P>0.05). Furthermore, the alkaline phosphatase activity was significantly elevated in the 200 ng/ml group, when compared with the control group. The RT-qPCR results demonstrated that the mRNA expression levels of RUNX2 and BGLAP were significantly increased at 200 ng/ml. Therefore, the present results suggested that the application of FGF-4 maintained cellular viability while enhancing the osteogenic differentiation of stem cell spheroids, at least partially by regulating RUNX2 and BGLAP expression levels.

Multi-domain structures in spheroidal Co nanoparticles

The structure of multi-domain micromagnetic states in hcp cobalt nanoparticles of spheroidal shape has been studied using numerical simulation in the range of diameters 20–200 nm. The single-domain diameters of the particles are determined depending on their aspect ratio. The complicated vortex structure of domain walls for two- and three-domain micromagnetic configurations is investigated. It has been shown that three domain states are actually strongly deformed two vortex states. In hcp cobalt particles of sufficiently large sizes two types of three-domain micromagnetic states with close total energies have been obtained. They differ in different magnetization directions of the exchange cores of the vortex domain walls. The remanent magnetization of particles has been calculated for two- and three-domain micromagnetic states. The single-domain diameters of fcc cobalt nanoparticles with cubic type of magnetic anisotropy were also calculated.

Expansion of deformed harmonic oscillator wavefunctions in terms of spherical wavefunction bases: deformation effects

The interbasis expansion of deformed cylindrical 3D harmonic oscillator (HO) wavefunctions in terms of spherical wavefunction bases is introduced. The spatial overlap integral is rewritten in a simplified form and presented in terms of the axis ratio of the deformed nucleus. Deformed nuclear spheroidal shapes are considered, including both quadrupole and hexadecapole deformations. The effect of deformation on the oscillator lengths of deformed 3D-HO, and in turn on the spatial overlap coefficients, is discussed. For the description of the geometrical shape of deformed nuclear systems, the collective and extended Nilsson models for surface parametrization are used.

Laboratory Study of Bilateral Supernova Remnants and Continuous MHD Shocks

Abstract Many supernova remnants (SNRs), such as G296.5+10.0, exhibit an axisymmetric or barrel shape. Such morphologies have previously been linked to the direction of the Galactic magnetic field, although this remains uncertain. These SNRs generate magnetohydrodynamic shocks in the interstellar medium, modifying its physical and chemical properties. The ability to study these shocks through observations is difficult due to the small spatial scales involved. In order to answer these questions, we perform a scaled laboratory experiment in which a laser-generated blast wave expands under the influence of a uniform magnetic field. The blast wave exhibits a spheroidal shape, whose major axis is aligned with the magnetic field, in addition to a more continuous shock front. The implications of our results are discussed in the context of astrophysical systems.

Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu

Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels.

Dipolar interactions among magnetic dipoles of iron oxide particles dispersed in mili-size hydrogel beads

The recently published Mean Field Interacting Superparamagnet Model (MFISP model), which introduces the effective demagnetizing factor NE, is tested in specimens having a random-like spatial distribution of magnetic nanoparticles, where different hierarchies of clustering are present. These specimens are ferrogel PVA/iron oxide beads synthesized by a one-pot route, having spheroidal shapes and sizes of about 1 mm, and chain and disk-like arrays (superstructures) of beads. Raman analyses indicated that magnetic nanoparticles are composed by a mixture of magnetite and maghemite. Beads swell 208% by hydration in about 40 min.The increase of the ac susceptibility as a function of hydration time closely reflects the effect of bead swelling, in agreement with the expected diminution of dipole–dipole interactions. Measured susceptibility is analyzed in terms of the susceptibility χ of non-interacting particles and the effective demagnetizing factor NE of the specimen, which depends on swelling. The Specific Absorption Rate of electromagnetic power by the beads grows with the hydration time in agreement with ac susceptibility behavior.For long hydration times susceptibility and high field magnetization decrease. This is explained by the occurrence of oxidation of magnetite/maghemite to hematite.Isothermal magnetization experiments are performed on each superstructure in two perpendicular principal directions each. Results are consistently described with the MFISP model by considering two hierarchies of clustering: beads themselves and clusters within the beads.From the whole set of experiments, it is possible to estimate values for the volume fractions of particles in clusters and clusters in beads, given by xpc=0.46(15) and xcb=0.16(5). The susceptibility of non-interacting particles, χ=13(4), is also obtained, which results about five times larger than the measured (apparent) one.The MFISP model proves to be a convenient and efficient tool for the analysis of magnetization studies of complex 3d dispersions of magnetic nanoparticles, allowing an experimental determination of relevant physical information, otherwise not accessible by magnetic measurements.

On the interaction between γ′′ precipitates and dislocation microstructures in Nb containing single crystal nickel-base alloys

The precipitation of the metastable γ′′ phase has been studied in a Nb containing nickel-based alloy in single crystalline state, with a composition close to the commercially available superalloy IN718. Solution heat treatment and isothermal aging treatment are applied to undeformed single crystalline samples.We focus on the investigation of heterogeneous γ′′ precipitation on dislocation sites, without the interference of grain boundaries or co-precipitation with other phases. The γ′′ precipitation microstructure after aging is found to be strongly related to the dislocation microstructure before aging. The dislocations found in the undeformed specimens have been generated during the dendritic solidification or the water quenching after solution heat treatment.Two specific patterns dominate the precipitation microstructure after aging. First, some γ′′ particles precipitate along curved lines formed initially by the dislocations during solution heat treatment along the dendritic boundary. Second, γ′′ particles are found to be arranged along the dislocation in slip planes, which can be seen as largely extended straight lines parallel to the 〈011〉 directions within the (001) plane, similar to a basket weave structure. Such an aligned arrangement of γ′′ particles has been previously observed in polycrystalline IN718 within individual grains (Choi and Choi, 1972). In contrast, the bands of numerous γ′′ particles can span the whole sample of millimeter size in single crystals, cutting several hundred dendrite cores. All γ′′ particles are in the shape of an oblate spheroid, where the normals of the plates are pointing in 〈001〉 directions.

A coupled photogrammetric–finite element method approach to model irregular shape product freezing: Mozzarella cheese case

The freezing process can be industrially performed to extend shelf life and to improve exportability of Italian high-moisture Mozzarella cheese. This cheese is usually characterized by a non-regular spheroidal shape that may be responsible for local differences of temperature on the surface and that can influence the overall freezing time. In this work, Mozzarella freezing was modelled by coupling the finite element method and a photogrammetric procedure that permitted to reconstruct the three-dimensional domain of the product. Computational models were validated by performing experimental trials, and results were accurate (root mean square error<1.47°C). With the photogrammetric technique it was possible to estimate volume, surface area, shape and size of the cheeses, and to study temperature–surface distribution that was found to be non-homogeneous. Freezing models highlighted that the surface area-to-volume ratio of the product, that ranged between 1.09 and 1.15cm−1, is one of the most critical parameters that define the freezing time of the cheese. A geometrical approximation of the cheese based on the surface area-to-volume ratio, showed good accuracy in terms of freezing times. These models can be valuable for Mozzarella cheese freezing optimization and design, to recover efficiency and to improve quality.

Microfluidic Biofabrication of 3D Multicellular Spheroids by Modulation of Non-geometrical Parameters.

Three-dimensional (3D) cell spheroids are being increasingly applied in many research fields due to their enhanced biological functions as compared to conventional two-dimensional (2D) cultures. 3D cell spheroids can replicate tissue functions, which enables their use both as in vitro models and as building blocks in tissue biofabrication approaches. In this study, we developed a perfusable microfluidic platform suitable for robust and reproducible 3D cell spheroid formation and tissue maturation. The geometry of the device was optimized through computational fluid dynamic (CFD) simulations to improve cell trapping. Experimental data were used in turn to generate a model able to predict the number of trapped cells as a function of cell concentration, flow rate, and seeding time. We demonstrated that tuning non-geometrical parameters it is possible to control the size and shape of 3D cell spheroids generated using articular chondrocytes (ACs) as cellular model. After seeding, cells were cultured under perfusion at different flow rates (20, 100, and 500 μl/min), which induced the formation of conical and spherical spheroids. Wall shear stress values on cell spheroids, computed by CFD simulations, increased accordingly to the flow rate while remaining under the chondroprotective threshold in all configurations. The effect of flow rate on cell number, metabolic activity, and tissue-specific matrix deposition was evaluated and correlated with fluid velocity and shear stress distribution. The obtained results demonstrated that our device represents a helpful tool to generate stable 3D cell spheroids which can find application both to develop advanced in vitro models for the study of physio-pathological tissue maturation mechanisms and to obtain building blocks for the biofabrication of macrotissues.

Structural Analysis of Xanthan GUM-FE (III) Capsules

In this work, the formation of capsules in xanthan gum and complexing solutions of Fe III is structurally evaluated. These capsules have a spheroid shape that, when dried, collapse into disc shapes. These spheroids are made up of microspheres that partially explain this collapse. The backscattered SEM image shows areas rich in Fe and others poorer in this metal, the EDX analysis confirms this. FTIR chromatograms show a clear shift at approximately 1620 cm-1 due to the formation of the xanthan gum-Fe III complex. This work also proposes a structure, theoretically demonstrated, between xanthan gum and Fe III, which can explain what the biopolymeric structure bending procedure is like due to the presence of Fe III, a model called TransbiHook.

Multi-Spheroid-Loaded Human Acellular Dermal Matrix Carrier Preserves Its Spheroid Shape and Improves In Vivo Adipose-Derived Stem Cell Delivery and Engraftment.

Current in vivo adult stem cell delivery presents limited clinical effects due to poor engraftment and survival. To overcome current challenges in cell delivery and promote surgical cell delivery for soft tissue repair, a multi-spheroid-loaded thin sectioned acellular dermal matrix (tsADM) carrier which preserves loaded spheroids' three-dimensional (3D) structure, was developed. Adipose-derived stem cells (ASCs) were used for spheroid delivery. After generating spheroids in 3D cell culture dishes, spheroid plasticity and survival in-between coverslips were evaluated. Spheroids were loaded onto tsADM, their shape changes were followed up for 14days, and then imaged. Spheroid adhesion stability to tsADM against shear stress was also evaluated. Finally, cell delivery efficacy was compared with cell-seeded tsADM by in vivo implantation and histological evaluation. Spheroids withstood cyclic compression stress and maintained their 3D shape without fusion after 48h of culture in-between coverslips. Cell survival improved when spheroids were cultured on tsADM in-between the coverslips. Spheroid-loaded tsADM with coverslips maintained their spheroid outline for 14days of culture whereas without coverslips, the group lost their outline due to spreading after 4 days in culture. Spheroids loaded onto tsADMs were more stable after six rather than 3 days in culture. Spheroid-loaded tsADMs showed about a 2.96-fold higher ASCs transplantation efficacy than cell-seeded tsADMs after 2 weeks of in vivo transplantation. These results indicate that transplantation of spheroid-loaded tsADMs significantly improved cell delivery. These findings suggest that a combined approach with other cells, drugs, and nanoparticles may improve cell delivery and therapeutic efficacy.

A new ureteroileal anastomosis technique in modified ileal orthotopic bladder substitution after radical cystectomy

BackgroundThe aim of this study is to describe a modified technique in ileal orthotopic bladder substitution with a new ureteroileal anastomosis.Case presentationAfter a classic open radical cystectomy with bilateral pelvic lymphadenectomy was performed extraperitoneally, a 56-cm ileal segment was used to construct the spheroidal shape bladder substitution. The 8-cm long proximal and distal ends of the ileal segment were used as afferent limbs. Two-centimeter ileal segments of afferent limbs were detubularized and transversally tubularized. The elongated ileal tube was anastomosed with the ureter in an end-to-end fashion. The pathway of the ureteroileal anastomosis was placed between the abdominal cutaneous fat and the anterior rectus muscular sheath. Perioperative data and long-term functional outcomes were assessed. Between December 2011 and December 2015, seven male patients underwent this procedure with a median 46 (30–77) months follow-up in our hospital. There was no difference between preoperative and postoperative estimated glomerular filtration rates (Z = − 1.693, P = 0.09). One of 14 sides had ureteroileal anastomotic stenosis; two of 14 sides in one patient had ureteroileal anastomotic stenosis caused by invasion of pelvic recurrence 15 months postoperatively. Reflux was completely prevented by placing pressure on the corresponding point on the abdominal surface when voiding urine in all patients.ConclusionsWe describe a feasible technique modification in detail, which provides some advantages for effective anti-reflux by mechanical finger pressing and abdominal contraction, a low incidence of stricture, and ease for a secondary operation in the long-term follow-up period.

Contribution of magma mixing to the formation of porphyry-skarn mineralization in a post-collisional setting: The Machangqing Cu-Mo-(Au) deposit, Sanjiang tectonic belt, SW China

The Machangqing Cu-Mo-(Au) deposit in the central of Jinshajiang–Red River fold belt is a Cenozoic porphyry-skarn deposit in the western Yangtze Craton, southwestern China. Igneous rocks at Machangqing mainly consist of mafic and felsic rocks, including mafic dykes and barren syenite porphyry, as well as mineralized monzonite and granite porphyries with mafic microgranular enclaves (MMEs) in the ore-bearing porphyries. In this study, we compiled new and published geochemical and isotopic data for these intrusions, their MMEs and ore sulfides from the Machangqing deposit. Both mineralized and barren felsic porphyries, MMEs and mafic dyke were formed during the late Eocene (33–37 Ma), and have shoshonitic affinities (K2O + Na2O > 6 wt%, K2O/Na2O > 1 and Sr/Y > 40) ratios. They are enriched in LILE and LREE, but depleted in HFSE. Both mineralized and barren felsic porphyries are characterized by high SiO2 (64.67–72.81 wt%) and Al2O3 (13.43–16.10 wt%), but low Cr (average 37.63 ppm) and Ni (average 24.64 ppm) contents and low Mg# values (11–66). They have low whole–rock εNd(t) (–6.5 to –3.3) and relatively high (87Sr/86Sr)i (0.7061–0.7076), which fall inside the range of coeval mafic rocks in western Yunnan. The geochronological, geochemical and isotopic evidence suggest that the felsic magmas were formed by partial melting of the juvenile lower crust that had been injected by shoshonitic mafic magma as documented by the MMEs. The mafic dykes have high Mg# (71–76), Cr (average 492 ppm), Ni (average 195 ppm) contents, and were likely derived from partial melting of upper mantle sources metasomatized by paleo-subduction processes. The MMEs at Machangqing were produced by the mingling of metasomatized mantle-derived mafic melts with the juvenile Neoproterozoic thickened crust-derived felsic melts. The MMEs have spheroidal shapes and contain acicular apatite, indicating that the MMEs represent globules of coeval mafic melt injected into and partly assimilated by the felsic magmas. The ore sulfides have similar trace elemental and Pb isotopic features (206Pb/204Pb = 18.562–18.659; 207Pb/204Pb = 15.628–15.664; 208Pb/204Pb = 38.894–38.986) to the coeval mafic dykes, and their S-isotopic compositions (-2.24 to + 3.5‰) resemble typical mantle-source sulfides, suggesting a metallogenetic link with the coeval mafic magmas/melts and MMEs. Magmas of both the ore-bearing and barren porphyries are relatively oxidized in the FMQ to MH range (zircon Ce4+/Ce3+ = 87–950, log(fO2) = –22 to −5), although the ore-bearing ones are more oxidized. Petrological modelling suggests that the mineralized porphyries are derived from magma mixing dominated by partial melts of metasomatically-enriched mafic mantle, while the barren porphyries are products of magma mixing dominated by a juvenile lower crust component. We propose that magma mixing between lower crustal material with injected mafic mantle-derived magma has provided sufficient metals, sulfur and water to form the Machangqing Cu-Mo-(Au) deposit. The hydrous mafic magmas may have also remobilized the residual sulfides remaining in the continental lithospheric mantle (CLM), thus adding to the metal budget of these fertile magmas.

Algorithms of the Hybrid Projection Method Applied for Analyzing the Excitation of an Inhomogeneous Dielectric Body of Revolution by a Radial Magnetic Dipole

A revolution body consisting of a homogeneous dielectric sphere and an exterior inhomogeneous dielectric layer is considered. The problem of excitation of this body by a magnetic dipole located on the revolution axis is analyzed. Solution algorithms based on the hybrid projection method are developed. The method includes the projection of electromagnetic fields onto transverse spherical functions and application of the 1D finite element method for the solution of the obtained system of ordinary differential equations. The algorithms are also generalized to the case of the perfectly conducting interior sphere. The comparison results characterizing the efficiency of the method are presented. The calculation results are given for the pattern of the dipole in the presence of a conducting sphere surrounded by an inhomogeneous dielectric shell having the shape of a prolate spheroid in one case and a plasma shell having the same shape in the other case.

Age‐Related Loss of Phrenic Motor Neurons: Reduced Myogenic Influence?

There is an age‐associated loss of phrenic motor neurons (PhMNs) and withdrawal of pre‐synaptic terminals at neuromuscular junctions (NMJs) in 24‐month old Fischer 344 (F344) rats. Previously, we showed that age‐related PhMN loss is concomitant with neuromuscular transmission failure and diaphragm muscle (DIAm) sarcopenia (an age‐related atrophy of muscle fibers and a decrease in specific force). It is unknown if pre‐synaptic terminal withdrawal precedes PhMN loss, which would implicate a reduction in a trophic influence emanating from muscle fibers (myogenic). We hypothesized that age‐related PhMN loss results from pre‐synaptic terminal withdrawal and reduced myogenic influence, which occurs predominantly at type IIx and/or IIb DIAm fibers (innervated by larger PhMNs). F344 rats were obtained from the National Institutes of Aging. Experimental ages were chosen to represent 100% and 50% survival at 6 months and 24 months‐old, respectively. PhMNs were first retrogradely labeled by intrapleural injection of cholera toxin‐subunit B (CTB), which is dependent on binding to pre‐synaptic terminal gangliosides. Thus, with pre‐synaptic terminal withdrawal, PhMNs would not be labeled. Subsequently (3 days after CTB), PhMNs were retrogradely labeled by sectioning the phrenic nerve and dipping the proximal end into a Rhodamine dextran (Rho) solution – this labeling is not dependent on pre‐synaptic terminals. CTB and Rho labeled PhMNs were visualized by confocal microscopy. Only optical slices containing the nucleus of Rho‐ and/or CTB‐labeled PhMNs were counted. We analyzed the differences in labeling of PhMNs by CTB and Rho in both age groups. In labeled PhMNs, short and long axis measurements were used to determine somal surface areas by assuming a prolate spheroid shape. In 6‐month old rats, there was no significant difference in the number of PhMNs labeled by CTB or Rho. In 24‐month old rats, the total number of labeled PhMNs was reduced compared to the 6‐month old rats, which primarily affected larger PhMNs. Furthermore, at 24‐months, fewer PhMNs were labeled with CTB compared to Rho and those labeled with Rho had larger somal surface areas. These results support our hypothesis that the age‐related loss of larger PhMNs results from pre‐synaptic terminal withdrawal and reduced myogenic influence.Support or Funding InformationSupport: NIH R01‐AG044615American Physiological Society

New charophyte assemblage from middle Miocene lacustrine deposits of Moneva (Ebro Basin, Spain)

Two new fossil charophyte species from middle Miocene lacustrine deposits of Moneva (Ebro Basin, NE Spain) are described and illustrated. Sphaerochara miocenica nov. sp. is represented by medium sized gyrogonites with a characteristic spheroidal shape and ornamented with numerous small and regularly spaced tubercles arranged along the spiral cells. Several specimens show an unusual carbonate encrusted layer that covers completely or partially the gyrogonite. Psilochara monevaensis nov. sp. is characterized by large gyrogonites, with typical prolate shape and protruding apical poles. A second population of S. miocenica nov. sp. from a distant early upper Miocene lacustrine basin located in the Middle East (Bekaa Valley, Lebanon), identified in a previous study as Sphaerochara sp., is described and illustrated here, allowing the comparison of these distant populations. Ecologically, the associated fauna and facies from both localities suggest that these taxa grew in very shallow athalassic lakes. Interestingly, S. miocenica nov. sp. having a wide geographic distribution in peri-Mediterranean lakes with variable salinity, may become a fossil guide for the Miocene, providing at the same time important palaeoecological information.

Computational fluid dynamic simulations of thermochemical conversion of pulverized biomass in a dilute flow using spheroidal approximation

A drag force model for spheroids, referred as the spheroid model, was implemented in OpenFOAM, in order to better predict the thermochemical conversion of pulverized biomass. Our previous work has found that the spheroid model predicts more dispersed results in terms of particle velocities and local concentrations comparing to other conventional particle models under non-reactive conditions. This work takes the spheroid model one step further, by validating against experiments performed under reactive conditions with a newly implemented heat transfer model for spheroids as well as updated devolatilization kinetic parameters. In addition, simulations were conducted in a configuration similar to a pilot-scale entrained flow gasifier for more realistic scenarios. Particle mass and axial velocity development were compared accordingly using four different modelling approaches with increasing complexity. When compared with models of spheroidal shape assumptions, the sphere and simplified non-sphere model predict 61% and 43% longer residence times, respectively. The combination of the spheroid shape assumption with the heat transfer model for spheroids tends to promote drying and devolatilization. On the other hand, the traditional spherical approach leads to longer particle residence times. These opposing effects are believed to be a major contributing factor to the fact that no significant differences among modelling approaches were found in terms of syngas production at the outlet. Furthermore, particle orientation information was reported in both experiments and simulations under reactive conditions. Its dependency on gas velocity gradient under reactive conditions is similar to what was reported under non-reactive conditions.

Climate Models and Remote Sensing Retrievals Neglect Substantial Desert Dust Asphericity

AbstractClimate models and remote sensing retrievals generally assume that dust aerosols are spherical or spheroidal. However, measurements show that dust aerosols deviate substantially from spherical and spheroidal shapes, as ratios of particle length to width (the aspect ratio) and height to width (height‐to‐width ratio) deviate substantially from unity. Here, we quantify dust asphericity by compiling dozens of measurements of aspect ratio and height‐to‐width ratio across the globe. We find that the length is on average 5 times larger than the height and that climate models and remote sensing retrievals underestimate this asphericity by a factor of ~3–5. Compiled measurements further suggest that North African dust becomes more aspherical during transport, whereas Asian dust might become less aspherical. We obtain globally‐averaged shape distributions, from which we find that accounting for dust asphericity increases gravitational settling lifetime by ~20%. This increased lifetime helps explain the underestimation of coarse dust transport by models.

Density Profiles of 51 Galaxies from Parameter-Free Inverse Models of Their Measured Rotation Curves

Spiral galaxies and their rotation curves have key characteristics of differentially spinning objects. Oblate spheroid shapes are a consequence of spin and reasonably describe galaxies, indicating that their matter is distributed in gravitationally interacting homeoidal shells. Here, previously published equations describing differentially spinning oblate spheroids with radially varying density are applied to 51 galaxies, mostly spirals. A constant volumetric density (ρ, kg m−3) is assumed for each thin homeoid in these formulae, after Newton, which is consistent with RCs being reported simply as a function of equatorial radius r. We construct parameter-free inverse models that uniquely specify mass inside any given r, and thus directly constrain ρ vs. r solely from velocity v (r) and galactic aspect ratios (assumed as 1:10 for spirals when data are unavailable). Except for their innermost zones, ρ is proven to be closely proportional to rn, where the statistical average of n for all 36 spirals studied is −1.80 ± 0.40. Our values for interior densities compare closely with independently measured baryon density in appropriate astronomical environments: for example, calculated ρ at galactic edges agrees with independently estimated ρ of intergalactic media (IGM). Our finding that central densities increase with galaxy size is consistent with behavior exhibited by diverse self-gravitating entities. Our calculated mass distributions are consistent with visible luminosity and require no non-baryonic component.