Dense Core Research Articles

Preparation of thermally stable egg white protein microgel particles as assisted by differently charged polysaccharides: A comparatively study

Egg white proteins (EWP) were prone to thermal aggregation under heat sterilization conditions, thereby limiting their application in the field of protein beverages. In this study, EWP were microgel particleized via polysaccharide-protein phase separation to enhance their resistance to thermal aggregation during processing. Results indicated that the charge characteristics of polysaccharides were crucial factors influencing their interaction with EWP. Microstructural and physicochemical properties indicated that egg white protein microgel particles (EMGP) with the bilayer structure formation (polysaccharide shell layer and dense protein core) could only be formed in the phase separation system of EWP and anionic polysaccharides (carboxymethyl cellulose sodium salt (low viscosity), carboxymethyl cellulose sodium salt (high viscosity), High-methoxyl pectin). Additionally, the EMGP exhibited uniform size, high denaturation extent and dense structure that effectively prevented structural unfolding and exposure of active sites upon reheating of the EWP. The thermal denaturation temperatures of the EMGP were significantly higher (up to 155.8 °C, 163.5 °C, 165.7 °C), compared to natural proteins (88.8 °C). Thermal stability experiments confirmed that the suspension of 5% w/v microgel particles maintained good flow ability after heating at 100 °C for 30 min, demonstrating excellent thermal stability suitable for high-temperature pasteurization conditions. Moreover, its uniform particle size and adsorption of polysaccharides improved storage stability. In contrast, groups other than anionic polysaccharides exhibited aggregation and gelation upon heating. Overall, this study demonstrated that preparing heat-stable EMGP effectively reduces aggregation in EWP beverages during heat-pasteurization, enhanced product sensory attributes, extended shelf-life, and expanded the application scope of EWP.

К оценке геодинамической устойчивости геосфер Земли

The Earth, as a system, is characterized by certain average state parameters (density, temperature). These parameters cannot but depend on similar states of internal geospheres (subsystems), which follow the unified law of increasing entropy of the cooling Earth from the center in the direction of the Earth's radius. As a model for assessing the dynamic stability of the Earth's internal geospheres relative to each other, the principle of the golden proportion (golden section) was used with the given parameters of density, temperature, power of the geospheres to the extreme ratios of their states at points (0.618; 1.618; 2.618), which determine the conditions for the stable dynamic equilibrium of the compared parameters of geospheres. And if these relations satisfied the known theoretical, model, geophysical data, then the conclusion was made that the geospheres in the compared parameter relations were in a state close to a stable dynamic equilibrium of the exchange of matter and energy between them. Otherwise, it was recognized that the compared geospheres of the Earth were in a state of either unstable dynamic equilibrium with an assessment of the level of this deviation from the golden numbers, or the known values of the density and temperature of the geospheres, as well as their structure, should be subject to clarification. Average model estimates of the parameters of the Earth's internal geospheres reach a stable dynamic equilibrium at a level of deviation from the golden numbers of up to 2.72 %. This allows estimating the model duration of the modern geological activity of the Earth for another 124 million years until the formation of a new state of the existing continents. The instability of the dynamic equilibrium of density and temperature of matter is established at the boundaries: continental and oceanic crust; oceanic crust and Golitsin layer; at the boundary between the outer part of the Earth's core and the lower mantle; inside the Earth's core at the level of identified transition zones in the four-layer core model. The presence of spheres with a high core density from 16.05 to 26.45 g/cm3 suggests the stratification of its central part into essentially gold and platinoid. The presence of instability boundaries in the dynamic state of geospheres is in good agreement with the concept of plate tectonics and with the depths of plume origin. It can be assumed that the relative equilibrium of the internal structure of the Earth will continue for about 124 million years until the beginning of the formation of a new Pangea Proxima, which, according to Cristofor Scotese, will arise in 200 million years.

Incorporation of nitrogen and oxygen in carbon: A highly tuned electrochemistry with facile synthesis and its influence on optical and electrode performance in supercapacitors

A new approach for synthesizing heteroatom-doped carbon nanostructures has been developed, in which nitrogen and oxygen have been effectively infused into the graphitic core using the required precursors. The heteroatoms incorporated into the carbon matrix and their corresponding structural features are examined. The observed X-ray diffraction pattern reveals the presence of amorphous carbon forms that resemble carbon nitride in their structure. The presence of additional N–O and C–O bonds gives strong evidence of a graphitic structure with oxygen and nitrogen incorporation, as shown by the Fourier transform-infrared peaks. The X-ray photoelectron spectroscopy analysis reveals important information regarding the bond formation in the graphitic core of the sample. The study focused on examining the porous and intricately interconnected network structures, showcasing a variety of particle morphologies, and was carried out using scanning electron and transmission electron microscopy. The lattice defects are investigated using transmission electron microscopy-high angle annular dark field technique to explore the surface morphology. The influence of incorporated O and N in carbon structure drastically reduced the electron density of the graphitic core. As a result, the absorption bands observed were around 300–400 nm, showing the semiconductors' absorption characteristics. Three-electrode electrochemical systems are fabricated with working electrodes based on COx and CNx materials. The COx and CNx-modified electrodes were meticulously tested for their performance in supercapacitor applications. The COx samples exhibit a significant specific capacity value of 439.20 C g−1 under a low current density of 4 A g−1. The CNx samples demonstrate a specific capacity of 420.00 C g−1 under 4 A g−1 current density.

Regional Difference and Spatial Convergence of Land Use Carbon Emissions in Three Urban Agglomerations of Yangtze River Economic Belt

It is of great significance to explore the regional differences of land use carbon emission （LUCE） in the Yangtze River Economic Belt and the path of coordinated emission reduction for regional sustainable development. Based on the LUCE estimation method, this study scientifically calculated the LUCE of the three major urban agglomerations of the Yangtze River Economic Belt （Yangtze River Delta, middle reaches of the Yangtze River, and Chengdu-Chongqing urban agglomeration） from 2010 to 2020. Kernel density estimation and the spatial convergence model were used to study the dynamic evolution, regional differences, and convergence characteristics of LUCE. The results showed that： ① The carbon absorption of forest land, water areas, grassland, and unused land were relatively small in terms of carbon emissions from cultivated land and construction land. The carbon emission of construction land increased gradually, whereas the carbon absorption of four carbon sinks fluctuated little during the study period. ② The core density curves of different urban agglomerations showed different distribution patterns, extensibility, and polarization characteristics but generally tended to be balanced. ③ From 2010 to 2020, the LUCE of the Yangtze River Economic Belt as a whole showed the spatio-temporal characteristics of increasing first and then decreasing and high in the east and low in the west. The LUCE of the central cities of the three urban agglomerations were at the highest level steadily, and stable coupling mechanisms had not been established between the economic development level and the ecological environment. ④ The LUCE of the three urban agglomerations in the Yangtze River Economic Belt all had absolute β convergence and also had conditional β convergence under the model control variables such as economic development level, urbanization level, industrial structure, population density, and environmental regulation, etc., and the conditional convergence speed was greater than the absolute convergence speed in each region. The convergence speed of the Yangtze River Delta urban agglomeration was the slowest. The above conclusions provide support for the coordinated emission reduction path of the three urban agglomerations in the Yangtze River Economic Belt and are also conducive to actively and steadily promoting the realization of the goals of carbon peak and carbon neutralization.

Compensating slice emittance growth in high brightness photoinjectors using sacrificial charge

Achieving maximum electron beam brightness in photoinjectors requires detailed control of the 3D bunch shape and precise tuning of the beam focusing. Even in state-of-the-art designs, slice emittance growth due to nonlinear space charge forces and partial nonlaminarity often remains non-negligible. In this work, we introduce a new means to linearize the transverse slice phase space: a sacrificial portion of the bunch’s own charge distribution, formed into a wavebroken shock front by highly nonlinear space charge forces within the gun, whose downstream purpose is to dynamically linearize the desired bunch core. We show that linearization of an appropriately prepared bunch can be achieved via strongly nonlaminar focusing of the sacrificial shock front, while the inner core focuses laminarly. This leads to a natural spatial separation of the two distributions: a dense core surrounded by a diffuse halo of sacrificial charge that can be collimated. Multiobjective genetic algorithm optimizations of the ultracompact x-ray free electron laser injector employ this concept, and we interpret it with an analytic model that agrees well with the simulations. In simulation, we demonstrate a final bunch charge of 100 pC, peak current ∼30 A, and a sacrificial charge of 150 pC (250 pC total emitted from cathode) with normalized emittance growth of <20 nm rad due to space charge. This implies a maximum achievable brightness approximately an order of magnitude greater than existing free electron laser injector designs. Published by the American Physical Society 2024

Flow physics of a subcritical carbon dioxide jet in a multiphase ejector

Existing literature on ejectors, different researchers utilized different turbulence models by their choice, neither analyzing the physics of turbulence nor providing any sufficient optical diagnostics of the flow field. In this article, the physics captured by the Unsteady Reynolds Averaged Navier–Stokes (URANS) and Large Eddy Simulation (LES) are compared based on well-posed boundary conditions obtained experimentally from a carbon dioxide (CO2) vapor compression cycle with an error ≤2.5%. The experimental results utilized for this study are at Reynold’s number (Re) 1.2e5 at the high-pressure inlet (motive flow) maintaining CO2 in subcritical state. The low-pressure inlet (suction flow) is maintained at Re = 9.8e4 with CO2 in vapor state, providing a pressure lift ratio of 1.2 at the diffuser outlet. Comparison of flow topologies with different URANS models reveals that only standard, Shear Stress Transport (SST) k−ω, and Reynold’s Stress Model-Shear Stress Gradient (RSM-SSG) are the suitable URANS models capturing a linearly increasing anisotropy tensor component with increasing strain in the flow. LES also predicted the similar physics. However, standard k−ω overpredicted the suction pressure beyond the acceptable uncertainty limits, which made it inapplicable. For the first time, a spatio-temporal representation of the flow topology with LES revealed the actual jet morphology of a CO2 ejector. Specifically, finger-like structures are key features to entrain more surrounding warm fluid into the colder dense core fluid at the cost of destabilizing and breaking up the jet by stretching the streamwise vortices and obstructing the increase in pressure-lift ratio.

Transmembrane and coiled-coil 2 associates with Alzheimer's disease pathology in the human brain.

Transmembrane and coiled-coil 2 (TMCC2) is a human orthologue of the Drosophila gene dementin, mutant alleles of which cause neurodegeneration with features of Alzheimer's disease (AD). TMCC2 and Dementin further have an evolutionarily conserved interaction with the amyloid protein precursor (APP), a protein central to AD pathogenesis. To investigate if human TMCC2 might also participate in mechanisms of neurodegeneration, we examined TMCC2 expression in late onset AD human brain and age-matched controls, familial AD cases bearing a mutation in APP Val717, and Down syndrome AD. Consistent with previous observations of complex formation between TMCC2 and APP in the rat brain, the dual immunocytochemistry of control human temporal cortex showed highly similar distributions of TMCC2 and APP. In late onset AD cases stratified by APOE genotype, TMCC2 immunoreactivity was associated with dense core senile plaques and adjacent neuronal dystrophies, but not with Aβ surrounding the core, diffuse Aβ plaques or tauopathy. In Down syndrome AD, we observed in addition TMCC2-immunoreactive and methoxy-X04-positive pathological features that were morphologically distinct from those seen in the late onset and familial AD cases, suggesting enhanced pathological alteration of TMCC2 in Down syndrome AD. At the protein level, western blots of human brain extracts revealed that human brain-derived TMCC2 exists as at least three isoforms, the relative abundance of which varied between the temporal gyrus and cerebellum and was influenced by APOE and/or dementia status. Our findings thus implicate human TMCC2 in AD via its interactions with APP, its association with dense core plaques, as well as its alteration in Down syndrome AD.

Investigating the Star-forming Sites in the Outer Galactic Arm

We aim to investigate the global star formation scenario in star-forming sites AFGL 5157, [FSR2007] 0807 (hereafter FSR0807), [HKS2019] E70 (hereafter E70), [KPS2012] MWSC 0620 (hereafter KPS0620), and IRAS 05331+3115 in the outer Galactic arm. The distribution of young stellar objects in these sites coincides with a higher extinction and H2 column density, which agrees with the notion that star formation occurs inside the dense molecular cloud cores. We have found two molecular structures at different velocities in this direction; one contains AFGL 5157 and FSR0807, and the other contains E70, [KPS2012] MWSC 0620, and IRAS 05331+3115. All these clusters in our target region are in different evolutionary stages and might form stars through different mechanisms. The E70 cluster seems to be the oldest in our sample; AFGL 5157 and FSR0807 formed later, and KPS0620 and IRAS 05331+3115 are the youngest sites. AFGL 5157 and FSR0807 are physically connected and have cold filamentary structures and dense hub regions. Additionally, the near-infrared photometric analysis shows signatures of massive star formation in these sites. KPS0620 also seems to have cold filamentary structures with the central hub but lacks signatures of massive stars. Our analysis suggests molecular gas flow and the hub filamentary star formation scenario in these regions. IRAS 05331+3115 is a single clump of molecular gas favoring low-mass star formation. Our study suggests that the selected area is a menagerie of star-forming sites where the formation of the stars happens through different processes.

Direct Observational Evidence of Multi-epoch Massive Star Formation in G24.47+0.49

Using new continuum and molecular line data from the Atacama Large Millimeter/submillimeter Array Three-millimeter Observations of Massive Star-forming Regions (ATOMS) survey and archival Very Large Array, 4.86 GHz data, we present direct observational evidence of hierarchical triggering relating three epochs of massive star formation in a ringlike H ii region, G24.47+0.49. We find from radio flux analysis that it is excited by a massive star(s) of spectral type O8.5V–O8V from the first epoch of star formation. The swept-up ionized ring structure shows evidence of secondary collapse, and within this ring, a burst of massive star formation is observed in different evolutionary phases, which constitutes the second epoch. ATOMS spectral line (e.g., HCO+(1–0)) observations reveal an outer concentric molecular gas ring expanding at a velocity of ∼9 km s−1, constituting the direct and unambiguous detection of an expanding molecular ring. It harbors twelve dense molecular cores with surface mass density greater than 0.05 g cm−2, a threshold typical of massive star formation. Half of them are found to be subvirial and thus in gravitational collapse making them the third epoch of potential massive star-forming sites.

Spectroscopic Survey of Faint Planetary-nebula Nuclei. V. The EGB 6-type Central Star of Abell 57* *Based on observations obtained with the Hobby–Eberly Telescope (HET), which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Ludwig–Maximillians–Universität München, and Georg–August Universität Göttingen. The HET is named in honor of its principal benefactors, William P. Hobby and

During our spectroscopic survey of central stars of faint planetary nebulae (PNe), we found that the nucleus of Abell 57 exhibits strong nebular emission lines. Using synthetic narrowband images, we show that the emission arises from an unresolved compact emission knot (CEK) coinciding with the hot (90,000 K) central star. Thus Abell 57 belongs to the rare class of “EGB 6-type” PNe, characterized by dense emission cores. Photometric data show that the nucleus exhibits a near-infrared excess, due to a dusty companion body with the luminosity of an M0 dwarf but a temperature of ∼1800 K. Emission-line analysis reveals that the CEK is remarkably dense (electron density ∼ 1.6 × 107 cm−3), and has a radius of only ∼4.5 au. The CEK suffers considerably more reddening than the central star, which itself is more reddened than the surrounding PN. These puzzles may suggest an interaction between the knot and central star; however, Hubble Space Telescope imaging of EGB 6 itself shows that its CEK lies more than ∼125 au from the PN nucleus. We discuss a scenario in which a portion of the asymptotic giant branch wind that created the PN was captured into a dust cloud around a distant stellar companion; this cloud has survived to the present epoch, and has an atmosphere photoionized by radiation from the hot central star. However, in this picture EGB 6-type nuclei should be relatively common, yet they are actually extremely rare; thus they may arise from a different transitory phenomenon. We suggest future observations of Abell 57 that may help unravel its mysteries.

Hydraulic pressure resistance of the ceramic resin composite buoyancy materials based on cylindrical tube configuration

Due to high modulus, high strength and low water absorption of the 99.5% alumina ceramic, the tubular ceramic resin composite (TCRC) has been designed and fabricated, which can provide a potential option for the deep-sea buoyancy materials. The reliability and applicability of TCRC under hydrostatic pressure are systematically discussed by means of theory, experiment and simulation. Circumferential instability and strength failure are two possible failure modes of the TCRC through theoretical analysis. The study indicates that the load-bearing capacity of TCRC decreases with the increase of the number of vertical/horizontal tube arrays m, the ratio of the inner to outer radius r/Rc of the ceramic tube or the ratio of the length to the outer radius L/Rc of the ceramic tube. Conversely, the load-bearing capacity of TCRC increases with the increase in the modulus of matrix phase Er. In addition, TCRC with parameters of “r/R-0.93/0.91-3X3-L40-E3.18” has excellent performance through experimental verification. That is, the core density and hydrostatic strength of the TCRC are 0.67 g/cm3 and 150.6 MPa, respectively. Better stated, our designed buoyancy material can be applied in the deep-sea environment of 12000m, which is the deepest spot on the ocean floor ever explored. The excellent performance of TCRC verifies the feasibility of ceramic circular honeycomb configuration in the application of hydrostatic pressure environment. Meanwhile, the buoyancy materials used in different water depths can be designed by changing the L/Rc or r/Rc of the round tube in circular honeycomb.

The Formation of Filaments and Dense Cores in the Cocoon Nebula (IC 5146)

We present 850 μm linear polarization and C18O (3 − 2) and 13CO (3 − 2) molecular line observations toward the filaments (F13 and F13S) in the Cocoon Nebula (IC 5146) using the JCMT POL-2 and Heterodyne Array Receiver Program instruments. F13 and F13S are found to be thermally supercritical with identified dense cores along their crests. Our findings include that the polarization fraction decreases in denser regions, indicating reduced dust grain alignment efficiency. The magnetic field vectors at core scales tend to be parallel to the filaments, but disturbed at the high density regions. Magnetic field strengths measured using the Davis–Chandrasekhar–Fermi method are 58 ± 31 and 40 ± 9 μG for F13 and F13S, respectively, and it reveals subcritical and sub-Alfvénic filaments, emphasizing the importance of magnetic fields in the Cocoon region. Sinusoidal C18O (3 − 2) velocity and density distributions are observed along the filaments’ skeletons, and their variations are mostly displaced by ∼1/4 × the wavelength of the sinusoid, indicating core formation occurred through the fragmentation of a gravitationally unstable filament, but with shorter core spacings than predicted. Large-scale velocity fields of F13 and F13S, studied using 13CO (3 − 2) data, present a V-shape transverse velocity structure. We propose a scenario for the formation and evolution of F13 and F13S, along with the dense cores within them. A radiation shock front generated by a B-type star collided with a sheet-like cloud about 1.4 Myr ago. The filaments became thermally critical due to mass infall through self-gravity ∼1 Myr ago, and subsequently, dense cores formed through gravitational fragmentation, accompanied by the disturbance of the magnetic field.

A study of the dynamic evolution of spherical gravitating systems

This article discusses the problems of origin and evolution and issues of numerical modeling of spherical systems, such as clusters of galaxies, globular clusters or E0 galaxies, characterized by massiveness and relatively old age, including up to 1000 bodies. First, observational data on galaxy clusters and their results are analyzed, including using a numerical method. Methods for numerical modeling of the evolution of spherical systems are studied. Two models are analyzed: the first is spherically homogeneous, with an isotropic distribution, and the second is with a particle distribution obeying the Plummer model. Changes in the position of bodies in the system and the distribution of velocities for different moments of time were obtained for each individual model. The calculation results are presented in the form of graphs. In the first model, at an early stage of evolution, the system collapses: a dense core is formed in the center, and a shell is formed around it. It is shown that over time the concentration of the nucleus decreases and it begins to stretch and the size of the system begins to increase. In this case, the distribution of bodies in the system obeys the Gaussian distribution and remains unchanged until the end of evolution. The second model also shows that at an early stage of evolution, the system collapses: then the system contracts and a compacted core forms in the center. The difference between the second model and the first is that a dense halo appears around the nucleus. It is found that sometimes in the early stages of evolution the system is slightly elongated and then tends to a spherical shape. It is also discovered that when solving the modeling of spherical systems, the choice of initial conditions plays an important role

Turbulence-reduced high-performance scenarios in Wendelstein 7-X

In the Wendelstein 7-X (W7-X) stellarator, turbulence is the dominant transport mechanism in most discharges. This leads to a ‘clamping’ of ion temperature over a wide range of heating power, predominantly flat density profiles where hollow profiles driven by neoclassical thermo-diffusion would be expected and by rapid impurity transport in injection experiments. Significantly reduced turbulent transport is observed in the presence of strong core density gradients found transiently after core pellet injection and irregularly after boronisation or boron pellet injection. Density peaking is also achieved in a controlled manner in purely neutral beam heated discharges where particle transport analysis reveals an abrupt reduction in the main-ion particle flux leading to significant density profile peaking not explained by the NBI particle source alone. The plasmas exhibit a heat diffusivity of around χ=0.25±0.1m2 s−1 at mid radius, a factor of around 4 lower than ECRH dominated discharges. Despite the improved confinement, the achieved ion temperature is limited by broader heat deposition and the lower power-per-particle given the higher density. This is overcome with limited reintroduction of ECRH power, where the low heat diffusivity diffusivity is maintained, the density rise supressed and ion temperatures above the clamping limit are achieved. The applicability of these plasmas for a high performance scenario on transport relevant time scales is assessed, including initial predictions for planned heating upgrades of W7-X, based on a range of assumptions about particle transport.

Cryo-ET reveals the in situ architecture of the polar tube invasion apparatus from microsporidian parasites.

Microsporidia are divergent fungal pathogens that employ a harpoon-like apparatus called the polar tube (PT) to invade host cells. The PT architecture and its association with neighboring organelles remain poorly understood. Here, we use cryo-electron tomography to investigate the structural cell biology of the PT in dormant spores from the human-infecting microsporidian species, Encephalitozoon intestinalis . Segmentation and subtomogram averaging of the PT reveal at least four layers: two protein-based layers surrounded by a membrane, and filled with a dense core. Regularly spaced protein filaments form the structural skeleton of the PT. Combining cryo-electron tomography with cellular modeling, we propose a model for the 3-dimensional organization of the polaroplast, an organelle that is continuous with the membrane layer that envelops the PT. Our results reveal the ultrastructure of the microsporidian invasion apparatus in situ , laying the foundation for understanding infection mechanisms.

Probing the sterile neutrino dipole portal with SN1987A and low-energy supernovae

Beyond the Standard Model electromagnetic properties of neutrinos may lead to copious production of sterile neutrinos in the hot and dense core of a core-collapse supernova. In this work, we focus on the active-sterile transition magnetic moment portal for heavy sterile neutrinos. Firstly, we revisit the SN1987A cooling bounds for dipole portal using the integrated luminosity method, which yields more reliable results (especially in the trapping regime) compared to the previously explored via emissivity loss, also known as the Raffelt criterion. Secondly, we obtain strong bounds on the dipole coupling strength reaching as low as 10−11 GeV−1 from energy deposition, i.e., constrained from the observation of explosion energies of underluminous Type IIP supernovae. In addition, we find that sterile neutrino production from Primakoff upscattering off of a proton dominates over scattering off of an electron for low sterile neutrino masses. Published by the American Physical Society 2024

Two-Photon Planar Laser-Induced Fluorescence Of Near-Wall CO During The Interaction Between A Flame And A Cooling Air Film

Reducing the anthropogenic pollutant emissions is a major concern in the aeronautical community. Implementing high-power density core engines made of lighter materials would undoubtedly increase the thermal efficiency and reduce CO 2 emissions. Nevertheless, near-wall combustion processes will become significant, raising concerns regarding thermal management. As a result, walls in aero-engine combustors are commonly cooled, but it also introduces more complex physical phenomena associated to pollutant formation during flame-cooling air interaction (FCAI). This experimental study aims at elucidating the role of the cooling air film on CO emissions during FCAI. The experiments are conducted in an atmospheric pressure and optically-accessible lab-scale combustion test rig dedicated to near-wall combustion. It generates a lean premixed turbulent methane/air V-shaped flame, with one branch of the flame that interacts with an oil-cooled stainless-steel wall. A splash-cooling plate system enables to generate a momentum-controlled parietal cooling air film. The novelty of this study is to develop and implement planar laser-induced fluorescence of the CO molecule (CO-PLIF), complemented by planar laser-induced fluorescence of the OH radical (OH-PLIF) as well as global CO emissions in the exhaust gases. Results show that the excitation of the Hopfield-Birge system enables to detect the AN ngström bands and the third positive system. However, significant interferences with C 2 and CN emissions are highlighted, being more pronounced in rich combustion conditions, and originating from the incomplete fuel oxidation as well as the high energy density of the two-photon excitation process. A broadband collection strategy of the AN ngström bands is selected, since these interferences are limited in lean combustion regimes. The analysis of the flame dynamics indicates that the increase of the cooling air film momentum shifts the reactive flow away from the wall, but also controls the flame wrinkling through modified aerodynamics. As a result, the flame is not influenced anymore by thermal quenching processes, and can effectively burn further away from the wall. Global emission measurements indicate an increase in CO when the cooling air film momentum increases. While thermal quenching favors a faster oxidation downstream of the flame, the establishment of the cooling air film leads to a longer flame with more production areas. CO-PLIF imaging concurs this phenomenon, with a CO distribution all along the wall when the cooling air film is well established.

Herschel Gould Belt Survey in Taurus – II. A census of dense cores and filaments in the TMC1 region

ABSTRACT We present a catalogue of dense cores and filaments in a $3.8^\circ \times 2.4^\circ$ field around the TMC1 region of the Taurus molecular cloud. The catalogue was created using photometric data from the Herschel SPIRE and PACS instruments in the 70, 160, 250, 350, and 500 μm continuum bands. Extended structure in the region was reconstructed from a Herschel column density map. Power spectra and probability density functions (PDFs) of this structure are presented. The PDF splits into lognormal and power-law forms, with the high-density power-law component associated primarily with the central part of TMC1. The total mass in the mapped region is 2000 M$_\odot$, of which 34 per cent is above an extinction of $A_V\sim 3$ mag – a level that appears as a break in the PDF and as the minimum column density at which dense cores are found. A total of 35 dense filaments were extracted from the column density map. These have a typical full width at half-maximum (FWHM) width of 0.07 pc, but the TMC1 filament itself has a mean FWHM of $\sim 0.13$ pc. The thermally supercritical filaments in the region are aligned orthogonal to the prevailing magnetic field direction. Derived properties for the supercritical TMC1 filament support the scenario of it being relatively young. A catalogue of 44 robust and candidate prestellar cores is created and is assessed to be complete down to 0.1 M$_\odot$. The combined prestellar core mass function for the TMC1 and L1495 regions is well fit by a single lognormal distribution and is comparable to the standard initial mass function.

Early Planet Formation in Embedded Disks (eDisk). XV. Influence of Magnetic Field Morphology in Dense Cores on Sizes of Protostellar Disks

The magnetic field of a molecular cloud core may play a role in the formation of circumstellar disks in the core. We present magnetic field morphologies in protostellar cores of 16 targets in the Atacama Large Millimeter/submillimeter Array large program “Early Planet Formation in Embedded Disks (eDisk),” which resolved their disks with 7 au resolutions. The 0.1 pc scale magnetic field morphologies were inferred from the James Clerk Maxwell Telescope POL-2 observations. The mean orientations and angular dispersions of the magnetic fields in the dense cores are measured and compared with the radii of the 1.3 mm continuum disks and the dynamically determined protostellar masses from the eDisk program. We observe a significant correlation between the disk radii and the stellar masses. We do not find any statistically significant dependence of the disk radii on the projected misalignment angles between the rotational axes of the disks and the magnetic fields in the dense cores, nor on the angular dispersions of the magnetic fields within these cores. However, when considering the projection effect, we cannot rule out a positive correlation between disk radii and misalignment angles in three-dimensional space. Our results suggest that the morphologies of magnetic fields in dense cores do not play a dominant role in the disk formation process. Instead, the sizes of protostellar disks may be more strongly affected by the amount of mass that has been accreted onto star+disk systems, and possibly other parameters, for example, magnetic field strength, core rotation, and magnetic diffusivity.

The effects of stellar feedback on molecular clumps in the Lagoon Nebula (M8)

Context. The Lagoon Nebula (M8) is host to multiple regions with recent and ongoing massive star formation, due to which it appears as one of the brightest H II regions in the sky. M8-Main and M8 East, two prominent regions of massive star formation, have been studied in detail over the past few years, while large parts of the nebula and its surroundings have received little attention. These largely unexplored regions comprise a large sample of molecular clumps that are affected by the presence of massive O- and B-type stars. Thus, exploring the dynamics and chemical composition of these clumps will improve our understanding of the feedback from massive stars on star-forming regions in their vicinity. Aims. We established an inventory of species observed towards 37 known molecular clumps in M8 and investigated their physical structure. We compared our findings for these clumps with the galaxy-wide sample of massive dense clumps observed as part of the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL). Furthermore, we investigated the region for signs of star formation and stellar feedback. Methods. To obtain an overview of the kinematics and chemical abundances across the sample of molecular clumps in the M8 region, we conducted an unbiased line survey for each clump. We used the Atacama Pathfinder EXperiment (APEX) 12m submillimetre telescope and the 30 m telescope of the Institut de Radioastronomie Millimétrique (IRAM) to conduct pointed on-off observations of 37 clumps in M8. These observations cover bandwidths of 53 GHz and 40 GHz in frequency ranges from 210 GHz to 280 GHz and from 70 GHz to 117 GHz, respectively. Temperatures were derived from rotational transitions of acetonitrile, methyl acetylene, and para-formaldehyde. Additional archival data from the Spitzer, Herschel, MSX, APEX, WISE, JCMT, and AKARI telescopes were used to investigate the morphology of the region and to derive the physical parameters of the dust emission by fitting spectral energy distributions to the observed flux densities. Results. Across the observed M8 region, we identify 346 transitions from 70 different molecular species, including isotopologues. While many species and fainter transitions are detected exclusively towards M8 East, we also observe a large chemical variety in many other molecular clumps. We detect tracers of photo-dissociation regions (PDRs) across all the clumps, and 38% of these clumps show signs of star formation. In our sample of clumps with extinctions between 1 and 60 mag, we find that PDR tracers are most abundant in clumps with relatively low H2 column densities. When comparing M8 clumps to ATLASGAL sources at similar distances, we find them to be slightly less massive (median 10 M⊙) and have compatible luminosities (median 200 L⊙) and radii (median 0.16 pc). In contrast, dust temperatures of the clumps in M8 are found to be increased by approximately 5 K (25%), indicating substantial external heating of the clumps by radiation of the present O- and B-type stars. Conclusions. This work finds clear and widespread effects of stellar feedback on the molecular clumps in the Lagoon Nebula. While the radiation from the O- and B-type stars possibly causes fragmentation of the remnant gas and heats the molecular clumps externally, it also gives rise to extended PDRs on the clump surfaces. Despite this fragmentation, the dense cores within 38% of the observed clumps in M8 are forming a new generation of stars.