Spiral Filaments Research Articles

Fragmentation of dense rotation-dominated structures fed by collapsing gravo-magneto-sheetlets and origin of misaligned 100 au-scale binaries and multiple systems

ABSTRACT The majority of stars are in binary/multiple systems. How such systems form in turbulent, magnetized cores of molecular clouds in the presence of non-ideal magnetohydrodynamic (MHD) effects remains relatively underexplored. Through athena++-based non-ideal MHD adaptive mesh refinement simulations with ambipolar diffusion, we show that the collapsing protostellar envelope is dominated by dense gravo-magneto-sheetlets, a turbulence-warped version of the classic pseudodisc produced by anisotropic magnetic resistance to the gravitational collapse, in agreement with previous simulations of turbulent, magnetized single-star formation. The sheetlets feed mass, magnetic fields, and angular momentum to a Dense ROtation-Dominated (DROD) structure, which fragments into binary/multiple systems. This DROD fragmentation scenario is a more dynamic variant of the traditional disc fragmentation scenario for binary/multiple formation, with dense spiral filaments created by inhomogeneous feeding from the highly structured larger-scale sheetlets rather than the need for angular momentum transport, which is dominated by magnetic braking. Provided that the local material is sufficiently demagnetized, with a plasma-$\beta$ of 10 or more, collisions between the dense spiralling filaments play a key role in facilitating gravitational collapse and stellar companion formation by pushing the local magnetic Toomre parameter $Q_\mathrm{m}$ below unity. This mechanism can naturally produce in situ misaligned systems on the 100-au scale, often detected with high-resolution Atacama Large Millimeter Array (ALMA) observations. Our simulations also highlight the importance of non-ideal MHD effects, which affect whether fragmentation occurs and, if so, the masses and orbital parameters of the stellar companions formed.

Observational energy transfers of a spiral cold filament within an anticyclonic eddy

The ocean surface mixed layer represents a critical interface linking the ocean and atmosphere. The physical processes determining the surface mixed layer properties and mediate atmosphere–ocean exchange. Submesoscale processes play a key role in cross-scale oceanic energy transformation and the determination of surface mixed-layer properties, includingthe enhancement of vertical nutrient transport, leading to increased primary productivity. Herein, we presented observations ofthe spiral chlorophyll-a filament and its influence on turbulence within an anticyclonic eddy in thewestern South China Sea during August 2021. The filament had a negative Ertel potential vorticity associated with strong upwelled/downward currents (approximately 20–40 m/day). Across-filament sections of the in-situ profiles showed turbulent dissipation rates enhanced inthe filament. We suggested this enhancement values can be attributed tosubmesoscale processes, which accounted for 25 % of the total parameterized turbulent dissipation rates. The present parametrized submesoscale turbulent scheme overestimated the in-situ values. The filament transferred kinetic energy upward to anticyclonic eddy via barotropic instability and gained energy from the anticyclonic eddy via baroclinic instability. After kinetic energy budget diagnostic, we suggested besides symmetric instability, centrifugal instability and mixed layer baroclinic instability should also be included in the turbulence scheme to overcome the overestimation. The observeddual energy transfers between the anticyclonic eddy and filament, and the observed high turbulent energy dissipation within the filament, emphasized the need for these processes to be accurately parameterized regional and climate models.

Revisiting the black hole mass of M 87 using VLT/MUSE adaptive optics integral field unit data

Context. Stellar dynamic-based black hole mass measurements of M 87 are twice that determined via ionized gas kinematics; the former are closer to the mass estimated from the diameter of the gravitationally lensed ring around the black hole. Aims. Using a deeper and more comprehensive ionized gas kinematic data set, we aim to better constrain the complex morphology and kinematics of the nuclear ionized gas and thus gain insights into the reasons behind the disagreement between the mass measurements. Methods. We use new narrow field mode with adaptive optics and wide field mode integral field spectroscopic data from the Multi Unit Spectroscopic Explorer instrument on the Very Large Telescope to model the morphology and kinematics of multiple ionized gas emission lines (primarily Hα+[N II] λλ6548,6583 and [O I] λ6300) in the nucleus of M 87. We used Kinemetry to fit the position angle, inclination, and velocities of the subarcsecond ionized gas disk. We used KinMSpy to create simulated datacubes across a range of black hole masses and disk inclinations, and parameterized the differences of the resulting residual (observed minus simulated) velocity maps, in order to obtain the best-fit model. Results. The new deep data set reveals complexities in the nuclear ionized gas kinematics that were not seen in earlier sparse and shallower Hubble Space Telescope spectroscopy. Several ionized gas filaments, some with high flow velocities, can be traced down into the projected sphere of influence. However, not all truly pass close to the black hole. Additionally, we find evidence of a partially filled biconical outflow, aligned with the jet, with radial velocities of up to 400 km s−1. The subarcsecond rotating ionized gas “disk” is well resolved in our datacubes. The velocity isophotes of this disk are twisted, and the position angle of the innermost gas disk (≲5 pc) tends toward a value perpendicular to the radio jet axis. The complexity of the nuclear morphology and kinematics (the mix of a warped disk with spiral arms, large linewidths, strong outflows, and filaments crossing the black hole in projection) precludes the measurement of an accurate black hole mass from the ionized gas kinematics. Two results, each relatively weak but together more convincing, support a high-mass black hole (∼6.0 × 109 M⊙) in a low-inclination disk (i ∼ 25°) rather than a low-mass black hole (∼3.5 × 109 M⊙) in a i = 42° disk: (a) Kinemetry fits to the subarcsecond disk support inclinations of ∼20°–25° rather than 42°; and (b) velocity residual (observed minus simulated) maps with slightly smaller residuals are found for the former case. The specific (sub-Keplerian) radiatively inefficient accretion flow (RIAF) model previously proposed to reconcile the mass measurement discrepancy was also tested: the sub-Keplerian factor used in this model is not sufficiently small to make a high-mass black hole in a RIAF inflow masquerade as a low-mass black hole in a Keplerian inflow. In general, Keplerian disk models perform significantly better than the RIAF model when fitting the subarcsecond ionized gas disk. Conclusions. A disk inclination close to 25° for the nuclear gas disk (rather than the previously posited 42°) and the warp in the subarcsecond ionized gas disk help reconcile the contradictory nature of key earlier results: (a) the mass discrepancy between stellar and ionized gas black hole masses (our results support the former) and (b) the misorientation between the axes of the ionized gas disk and the jet (we find them to be aligned in both two and three dimensions). Furthermore, we identify a previously unknown 400 km s−1 (partially filled) biconical outflow along the (three-dimensional) jet axis and show that the velocities of the two largest ionized gas filaments at 8″–30″ nuclear distances can be explained primarily by rotation in the extension of the nuclear ionized gas disk (inclination ∼25°).

Progressive Damage Analysis for Multiscale Model of Linerless Composite Cryotank and Integrated Design

Linerless composite cryogenic tank is significant for weight reducing in launch vehicles, and a microscopic-to-macroscopic model is presented in this paper to capture the burst behaviors of the carbon-fiber-reinforced-composite cryotank. The hierarchical framework starts from the material components (carbon fiber and matrix) at microlevel, filament winding layups at mesolevel, and pressure tank at macrolevel. The locally exact homogenization theory is first introduced to generate stiffness degeneration coefficients with matrix crack and fiber fracture failure, which is compared with previous literature and good agreements are obtained. And 1° finite element representative model is then established considering spiral filament winding, and progressive damage analysis is finally conducted based on Hashin and Maximum stress criteria complied with ANSYS Parametric Design Language. In addition, the thermodynamic analysis is demonstrated by considering the integrated design structure with a corrugated sandwich cylindrical shell under multiple physical fields. The proposed multiscale model provides references for fuel cryotank design from a microscopic perspective to predict the burst pressure.

Gravity-driven Magnetic Field at ∼1000 au Scales in High-mass Star Formation

Abstract A full understanding of high-mass star formation requires the study of one of the most elusive components of the energy balance in the interstellar medium: magnetic fields. We report Atacama Large Millimeter/submillimeter Array (ALMA) 1.2 mm, high-resolution (700 au) dust polarization and molecular line observations of the rotating hot molecular core embedded in the high-mass star-forming region IRAS 18089−1732. The dust continuum emission and magnetic field morphology present spiral-like features resembling a whirlpool. The velocity field traced by the H13CO+ (J = 3−2) transition line reveals a complex structure with spiral filaments that are likely infalling and rotating, dragging the field with them. We have modeled the magnetic field and find that the best model corresponds to a weakly magnetized core with a mass-to-magnetic-flux ratio (λ) of 8.38. The modeled magnetic field is dominated by a poloidal component, but with an important contribution from the toroidal component that has a magnitude of 30% of the poloidal component. Using the Davis–Chandrasekhar–Fermi method, we estimate a magnetic field strength of 3.5 mG. At the spatial scales accessible to ALMA, an analysis of the energy balance of the system indicates that gravity overwhelms turbulence, rotation, and the magnetic field. We show that high-mass star formation can occur in weakly magnetized environments, with gravity taking the dominant role.

The Organization of Cloud-scale Gas Density Structure: High-resolution CO versus 3.6 μm Brightness Contrasts in Nearby Galaxies

Abstract In this paper we examine the factors that shape the distribution of molecular gas surface densities on the 150 pc scale across 67 morphologically diverse star-forming galaxies in the PHANGS-ALMA CO (2–1) survey. Dividing each galaxy into radial bins, we measure molecular gas surface density contrasts, defined here as the ratio between a fixed high percentile of the CO distribution and a fixed reference level in each bin. This reference level captures the level of the faint CO floor that extends between bright filamentary features, while the intensity level of the higher percentile probes the structures visually associated with bright, dense interstellar medium features like spiral arms, bars, and filaments. We compare these contrasts to matched percentile-based measurements of the 3.6 μm emission measured using Spitzer/IRAC imaging, which trace the underlying stellar mass density. We find that the logarithms of CO contrasts on 150 pc scales are 3–4 times larger than, and positively correlated with, the logarithms of 3.6 μm contrasts probing smooth nonaxisymmetric stellar bar and spiral structures. The correlation appears steeper than linear, consistent with the compression of gas as it flows supersonically in response to large-scale stellar structures, even in the presence of weak or flocculent spiral arms. Stellar dynamical features appear to play an important role in setting the cloud-scale gas density in our galaxies, with gas self-gravity perhaps playing a weaker role in setting the 150 pc scale distribution of gas densities.

Spiral antennas for the generation of bessel beams with tunable nondiffractive range

Backward cylindrical leaky waves radiating in the direction of their central axis represent an efficient solution for generating nondiffracting Bessel-like beams. The structures proposed so far to support such waves, constituted by concentric metal rings printed on a grounded dielectric slab, ensure the formation of nondiffractive field patterns with preset unchangeable configurations at a given frequency. Here, we propose the adoption of subwavelength spiral filaments with controlled patterning of the envelope figure by dynamic mechanical deformations, in order to achieve spatial tuning of the nondiffractive region in its size and shape. Precise guidelines and examples are provided to describe the proposed design technique and underline the inherent advantages of this alternative technological solution.

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Ultra structural study on different sensory structure and some associated body parts of mango mealy bug, Drosicha mangiferae (G.) by scanning electron microscopy

Split conformation of Chaetomium thermophilum Hsp104 disaggregase

Hsp104 and its bacterial homolog ClpB form hexameric ring structures and mediate protein disaggregation. The disaggregated polypeptide is thought to thread through the central channel of the ring. However, the dynamic behavior of Hsp104 during disaggregation remains unclear. Here, we reported the stochastic conformational dynamics and a split conformation of Hsp104 disaggregase from Chaetomium thermophilum (CtHsp104) in the presence of ADP by X-ray crystallography, cryo-electron microscopy (EM), and high-speed atomic force microscopy (AFM). ADP-bound CtHsp104 assembles into a 65 left-handed spiral filament in the crystal structure at a resolution of 2.7Å. The unit of the filament is a hexamer of the split spiral structure. In the cryo-EM images, staggered and split hexameric rings were observed. Further, high-speed AFM observations showed that a substrate addition enhanced the conformational change and increased the split structure's frequency. Our data suggest that split conformation is an off-pathway state of CtHsp104 during disaggregation.

A sticky thicket of glue cells: A comparative morphometric analysis of colloblasts in 20 species of comb jelly (phylum Ctenophora)

Ctenophores in the class Tentaculata are distinct from Cnidarians in that they use sticky, not stinging, tentacles to capture and subdue their prey. The structures that make these tentacles sticky are colloblasts, specialized multicellular adhesive structures for predation. Located on the tentacles, tentacle side-branches (tentilla), or oral tentilla, colloblasts are only found in comb jellies (phylum Ctenophora). To perform comparative anatomy of the diversity of ctenophore colloblasts, specimens were collected from the epi- to bathypelagic zones near the coasts of central California and the Hawaiian Islands using blue-water divers and remotely operated vehicles. Tentacle samples were immediately fixed in a 4% formalin solution at sea, and then prepared in the lab via secondary fixation in 2% OsO4 for scanning electron microscopy (SEM). Diversity of ultrastructural characteristics was observed using SEM, and the morphometrics of the collosphere, external secretion granules, and spiral filament were recorded for 20 species, within 9 families and 9 genera, including 13 undescribed species. Morphometry of colloblasts reveals that the shape of the collosphere (the organizational unit of sticky granules) falls into 3 classifications: spherical, ellipsoidal, or non-uniform. External secretion granule deposition falls into 2 categories: clustered or patterned; the cap cell membrane was either present or absent. This morphological variation is summarized graphically and will be useful to describe the functional diversity and feeding ecology of the interesting and controversial phylum Ctenophora.

Harvesting of Arthrospira platensis by flocculation with phytic acid from rice bran.

PA: Phytic acid; PUFAs: Polyunsaturated fatty acids; FAO: Food and Agriculture Organization; γ-PGA: Poly (γ-glutamic acid); CNF: Cellulose nanofibrils; NIES: National Institute for Environmental Studies; SOT: Spirulina-Ogawa-Terui; CG: Control group; pI: Isoelectric point.

Gap, shadows, spirals, and streamers: SPHERE observations of binary-disk interactions in GG Tauri A

Context.A large portion of stars is found to be part of binary or higher-order multiple systems. The ubiquity of planets found around single stars raises the question of whether and how planets in binary systems form. Protoplanetary disks are the birthplaces of planets, and characterizing them is crucial in order to understand the planet formation process.Aims.Our goal is to characterize the morphology of the GG Tau A disk, one of the largest and most massive circumbinary disks. We also aim to trace evidence for binary-disk interactions.Methods.We obtained observations in polarized scattered light of GG Tau A using the SPHERE/IRDIS instrument in theH-band filter. We analyzed the observed disk morphology and substructures. We ran 2D hydrodynamical models to simulate the evolution of the circumbinary ring over the lifetime of the disk.Results.The disk and also the cavity and the inner region are highly structured, with several shadowed regions, spiral structures, and streamer-like filaments. Some of these are detected here for the first time. The streamer-like filaments appear to connect the outer ring with the northern arc. Their azimuthal spacing suggests that they may be generated through periodic perturbations by the binary, which tear off material from the inner edge of the outer disk once during each orbit. By comparing observations to hydrodynamical simulations, we find that the main features, in particular, the gap size, but also the spiral and streamer filaments, can be qualitatively explained by the gravitational interactions of a binary with a semimajor axis of ~35 au on an orbit coplanar with the circumbinary ring.

The Effect of Different Filament Arrangements on Thermal and Optical Performances of LED Bulbs

The influences on thermal and optical performances of light emitting diode (LED) bulbs with three different filament arrangements are investigated in detail. The average junction temperature, temperature of the surface of the bulb, and luminous flux of three samples all increased with increasing power. The thermal performance test results show that between the average junction, temperature and power were linear. The junction temperatures of the three samples at a power of 3.5 W were 102.48, 98.46, and 88.88 °C. The optical performance test results revealed that the luminous flux and efficiency in the two vertical filament arrangements were closely related to each other and higher than that of the horizontal filament arrangement. A numerical model of LED filament bulbs was established by the Floefd 17.2 software for analyzing the temperature distribution of the cross section and the gas flow path inside the bulb. The simulation results illustrated that the average temperatures of three samples were 105.88, 101.83, and 96.12 °C. Additionally, the gas flow inside the bulb of the two vertical filament arrangements was subject to forming a thermal cycle during operation work more than that of the horizontal filament arrangement. As a result, the flexible spiral LED filament bulb is feasible as a new light source.

Optical clearing and shielding with fan-shaped vortex beams

We propose and demonstrate a new method for creation of fan-shaped optical vortex beams by rational phase modulation and assembly based on a well-known conical vortex phase. Our design is different from the previously proposed method for generation of power-exponential vortex beams. Such unconventional vortex beams consist of multiple spiral beam filaments (as the fan blades), and their overall beam size and spiral angle can be readily controlled by adjusting the parameters. Experimentally, two examples of applications are illustrated with such fan-shaped vortex beams: one is optical clearing through densely scattering particle suspensions; the other is optical shielding and transporting a target particle from the suspensions by adding a donut pattern in the center (as the fan head). We envisage such specially designed fan beams may be used as a multifunctional tool for microfluidic and biological applications that involve the complex environment of the living bodies, especially for active isolation or separation of a trapped particle from fluid environments of high particle concentrations.

Highly Embedded 8 μm cores of Star Formation in the Spiral Arms and Filaments of 15 Nearby Disk Galaxies

Abstract Spitzer Space Telescope observations of 15 spiral galaxies show numerous dense cores at 8 μm that are revealed primarily in unsharp mask images. The cores are generally invisible in optical bands because of extinction, and they are also indistinct at 8 μm alone because of contamination by more widespread diffuse emission. Several hundred core positions, magnitudes, and colors from the four InfraRed Array Camera bands are measured and tabulated for each galaxy. The larger galaxies, which tend to have longer and more regular spiral arms, often have their infrared cores aligned along these arms, with additional cores in spiral arm spurs. Galaxies without regular spirals have their cores in more irregular spiral-like filaments, with typically only one or two cores per filament. Nearly every elongated emission feature has 8 μm cores strung out along its length. The occurrence of dense cores in long and thin filaments is reminiscent of filamentary star formation in the solar neighborhood, although on a scale 100 times larger in galaxies. The cores most likely form by gravitational instabilities and cloud agglomeration in the filaments. The simultaneous occurrence of several cores with regular spacings in some spiral arms suggests that in these cases, all of the cores formed at about the same time and the corresponding filaments are young. Total star formation rates for the galaxies correlate with the total embedded stellar masses in the cores with an average ratio corresponding to a possible age between 0.2 and 2 Myr. This suggests that the identified cores are the earliest phase for most star formation.

Organic walled microfossils from the Neoproterozoic Owk Shale, Kurnool Group, South India

An assemblage of organic walled microfossils (OWM) of 17 taxa belonging to 10 genera is reported from the Neoproterozoic Owk Shale of the Kurnool Group, South India. The assemblage comprises sphaeromorphs, colonial aggregates, filamentous forms, spiral cylindrical filaments belonging to cyanobacteria, problematic acanthomorphic acritarchs, Netromorphic, Sphaeromorphic and Acantomorphic groups. The assemblage includes cyanobacteria: Siphonophycus kestron, S. robustum, S. typicum, S. solidum, Polytrichoides lineatus; Netromorphic acritarch: Arctacellularia tetragonala, Navifusa majensis, Jacutianema solubila; Sphaeromorphic acritarch: Ostiana microcystis, Synsphaeridium spp., Leiosphaeridia minutissima, L. tenuissima, L. crassa, L. jacutica, L. ternate; and Acanthomorphic acritarch: Cavaspina aff. C. acuminata and Variomargosphaeridium aff. V. litoschum. The age conundrum of Kurnool Group (Mesoproterozoic versus Neoproterozoic) is discussed. On the basis of the reported OWM assemblage the age of the Kurnool Group is established as Neoproterozoic.

Gas flows and disks in a young binary

Star Formation Many stars are in binary systems, pairs of stars gravitationally bound to each other, often with the two components having similar masses. It remains unclear how these systems assemble and accrete material. Alves et al. made high-resolution observations of a young binary star that is still in the process of forming. A large disk surrounds both stars, and each component also has its own smaller circumstellar disk. Spiral filaments of dust and gas connect the small disks to the larger one. Material is accreting preferentially onto the star that currently has a lower mass, driving the masses toward similar values. Science , this issue p. [90][1] [1]: /lookup/doi/10.1126/science.aaw3491

Online Packaging Method of Filament Cathode for Intelligent Manufacturing

It is challenging to automatically package spiral shaped filament cathodes that are widely used in worldwide microwave ovens. The difficulties include a fast packaging speed of over one parts per second and the dexterity required to handle tangling and embedding between spiral filaments’ multiple circles. In order to convert conventional labor intensive packaging lines of filament cathodes into automatic ones, an online fast automatic packaging method is reported. The method converts the fast incoming sequential flow of filament spirals into a batch of twenty-parallel queues with two stopping levers. The proposed method using two levers to release only the front twenty filaments at a time, one from each queue to fill one complete row of the plastic packaging tray. In this way, it speeds up packaging speed twenty times over conventional sequential packaging method. The inner diameter of the queue tube matches the outer diameter of the filament. It is this dimeter matching to eliminate the embedding problem occurred between neighboring filaments. The proposed method uses vibrating brush to decouple tangled filaments. Large number of validating experiments indicate that the proposed method could automatically package 200 filaments spirals within 2 minutes, with positional accuracy of over 97%. Thus, the proposed packaging method could meet the manufacturing requirement of filament cathodes, releasing four labors out of every production line at every work-shift. Further, this method also simultaneously improves the surface quality of the filaments by eliminating scratch caused by their sharp fresh-cutting cross sections.

PHYSICOCHEMICAL AND PHARMACEUTICAL CHARACTERISATION OF MUCILAGE FROM SWEET BASIL SEED

Objective: Gums and mucilages are of immense significance as excipients owing to their renewable natural sources, cheapness, ready availability, biodegradability, non-toxicity, ability to undergo hydration and swelling rapidly. To satisfy the ever-increasing demand for highly specific and functional excipients, sweet basil (Ocimum basilicum L.) has been selected for the purpose of isolation of mucilage from its seeds and its physicochemical and pharmaceutical characterisation.
 Methods: Physicochemical characterisation of sweet basil seed mucilage was carried out by FTIR spectroscopy, HPTLC, phytochemical tests, X-ray diffractometry, studies on mucilage hydration, water holding capacity and swelling behaviour. Determination of compressibility index, Hausner ratio and angle of repose was done as part of pharmaceutical characterisation of mucilage.
 Results: The geometric diameter, sphericity and surface area of the seed have been found to be 1.24±0.31 mm, 0.62±0.01 and 4.83±0.5 mm2 respectively. From microscopy, mucilage from seeds was seen to emerge as spiral filaments as soon as they were placed in water. The FTIR study reveals the mucilage to be a carbohydrate containing–OH groups with intermolecular hydrogen bonding as in polysaccharides, with 1→4 glycosidic bonds. Qualitative phytochemical screening of Ocimum basilicum L. seed mucilage (BSM) revealed the presence of non-reducing sugars, gums and mucilage. X-ray diffractogram presented its amorphous structure. The HPTLC profiles of BSM in n-butanol: acetic acid: water (4:1:1) at 254 nm and at 366 nm (before and after spraying with p-anisidine) revealed several bands with Rf values ranging from<0.1 to 0.5. The water-holding capacity of the mucilage has been found to be 97.5±2.4 g/g mucilage and swelling index values (0.1-0.5% w/v) were in the range of 100±10 to 200±13 at 25 °C. BSM was found to possess fair to passable flow property with Hausner’s ratio of 1.247 and angle of repose of 37.57°.
 Conclusion: Therefore, mucilage from sweet basil seed can be employed as an excipient in manufacture of tablets by wet granulation after addition of suitable lubricants and also in development of liquid dosage forms.

A novel concept to produce periodic varied structural composite yarn via cyclical changing of the spacing between filaments and the strand

In this study, a novel concept has been developed as a cyclical spacing-change method to produce periodic varied structural composite yarn. Geometrical analysis indicated that the cyclical change of spacing between filaments and the strand altered the yarn formation zone shapes from corefil to sirofil, causing cyclic yarn structure variations from the hairy core–sheath (corefil section) to the smooth spiral filament wrapping (sirofil section). A mechanical analysis revealed the corefil section with more twists was thinner than the sirofil section with fewer twists. Specifically, the cross-sectional diameter performed gradual periodic changes from the thick sirofil section to the thin corefil section. Then, an eccentric godet wheel device was used to conduct confirmatory experiments. Besides validating the theoretical analysis, the experimental results also showed that the novel concept yarn had the minimum hairiness and medium irregularity and strength after comparisons with sirofil and corefil yarns.