Dense Core Research Articles

Novel triply periodic minimal surfaces sandwich structures: Mechanical performance and failure analysis

AbstractSandwich structures are known for their exceptional mechanical properties and widespread applications. This study integrates additive manufacturing (AM) technology, experiments, theoretical equations, and numerical simulations to investigate a novel lightweight sandwich structure with a core based on Triply Periodic Minimal Surfaces (TPMS). The core incorporates Primitive, Neovius, and Diamond structures and is designed and manufactured using AM. Three‐point bending experiments are conducted to assess bending performance, failure modes, and energy absorption capability. A numerical model is established to analyze behavior under bending loads, validated through comparison with theoretical equations and numerical simulations, focusing on stress concentration areas. A parametric study investigates the effects of skin material, thickness, and TPMS core relative density on bending performance and energy absorption capacity. Furthermore, a functionally graded core layer with a gradient change in relative density is designed to study its influence on bending performance. The parameters of the core have a decisive impact on TPMS sandwich panel performance. This study demonstrates that sandwich structures with TPMS cores can be designed to possess desirable bending performance and energy absorption capacity, providing insights for future engineering applications.Highlights A novel TPMS sandwich structure is fabricated using 3D printing technology. The gradient relative density core is introduced. The bending performance and failure behavior of the structure are evaluated. A parametric study was conducted to investigate the effects on performance.

Spatial Distribution Characteristics and Sustainable Inheritance Strategies of National Traditional Fine Arts Intangible Cultural Heritage in China

A total of 417 intangible cultural heritage objects (ICHOs) are intertwined with traditional Chinese art, showcasing China’s rich historical heritage and distinctive creative allure. However, ICHOs currently grapple with a significant succession quandary due to modernization endeavors and the impacts of globalization. Hence, this study scrutinizes the spatial distribution of ICHO projects and inheritors and examines methodologies for inheriting these 417 ICHOs, employing approaches such as the closest neighbor index, Moran’s I index, kernel density estimation, geographic concentration analysis, and imbalance index assessment. Research indicates that ICHOs exhibit a spatial aggregation pattern, yet there is no substantial spatial correlation observed in their distribution. The national distribution highlights two core density zones: Beijing and Shanghai. In China, ICHO programs display uneven distribution across various types, levels, regions, and cultural zones. Regarding the ethnic composition of projects and inheritors, ICHO projects predominantly focus on the Han ethnic group, with a scattering of minority representations. Minority ICHO projects and inheritors are concentrated in central and eastern areas, while Han ICHO projects and inheritors are concentrated in central and western regions. Among the 148 ICHO projects lacking inheritors, 203 have one inheritor, and only 66 have several inheritors. Shanghai serves as the core density zone for 269 ICHO projects with inheritors, while Beijing holds that status for 148 ICHO projects without inheritors. Out of the 148 ICHO projects lacking inheritors, 115 belong to the Han ethnic group, with 33 split among 16 different ethnic minorities, and 2 have no inheritors. These disparities underscore the uneven distribution of ICHO projects and the critical issue of inheritance. This study identified education, tourism, digital communication, incentivizing inheritors, and international cooperation as potential strategies for preserving ICHA. Moreover, a sustainable inheritance pathway integrating government, education, tourism, and media is imperative for the effective perpetuation of ICHOs’ legacy.

#1978 Proteomic analysis of exosomes derived from mesangial cells treated with galactose-deficient IgA1

Abstract Background and Aims IgA nephropathy (IgAN) is an autoimmune disease characterized by IgA deposits that build up in the kidneys, inflame and damage glomeruli causing hematuria and proteinuria. It is a leading cause of chronic kidney disease, which often results in end-stage kidney disease. There is no disease specific treatment for IgAN. The glomerulus, in which IgA1 lacking galactose residues (gdIgA1) are deposited, consists of mesangial cells, podocytes, and endothelial cells. Crosstalk between the cell types allows the glomerulus to act as a unit and react to its dynamic environment. There is very little evidence on mesangial cell derived exosomes and their cargo to understand the pathological crosstalk signaling in the glomerulus of IgAN. We isolated exosomes from mesangial cells that were treated with patient-derived gdIgA1 and IgA1 complexes. Proteomic analysis was performed to identify the exosome cargo and delineate the signaling pathways leading to maladaptive paracrine crosstalk. From our study, we aim to understand the molecular targets for therapeutic strategies in IgAN. Method Human mesangial cells were treated with/without IgA1, gdIgA1 or IgG for 24 h. Cell culture supernatant was collected for exosome isolations. Exosomes were analyzed by size, morphology and number using TEM and NanoFCM. Exosome protein extracts were processed for LC-Tandem mass spectrometry analysis using filter-aided sample preparation protocol. Proteomic analysis was performed using Qlucore omics explorer and pathway analysis using Ingenuity Pathway Analysis (IPA). Exosome marker expressions such as CD63, CD81 and FLOT1 and proteome validation was performed using Western blotting. Statistical analysis was performed using GraphPad Prism and values <0.05 were considered significant. Results We confirmed the release of exosomes by mesangial cells in response to IgA1/gdIgA1 complexes. Exosomes were fewer in unstimulated cells as compared to IgA1/gdIgA1 treated cells. They showed round morphology with a dense core and uniform size distribution. Exosomes from treated cells showed a mean size of about 75 nm and concentration in the range of 1-2 × 10^10 particles/ml. While untreated cells showed a mean size of about 100 nm and concentration of about 1 × 10^9 particles/ml. We confirmed the protein expression of exosome markers such as CD63, CD81 and FLOT1. For the first time, we demonstrated global proteomics on exosomes from mesangial cells followed by pathway analysis. We have identified 89 unique proteins and pathways in exosomes derived from gdIgA1 treated mesangial cells that could mediate pathological signaling in the glomerulus in comparison to exosomes derived from IgA1 treated mesangial cells. Conclusion Our study provides an understanding of the pathological crosstalk signaling through exosomes and key molecular targets for IgAN.

The Effects of Induction Plasma Spheroidization on the Properties of Yttrium-Stabilized Zirconia Powders and the Performance of Corresponding Thermal Barrier Coatings for Gas Turbine Engine Applications

To modify the structure of thermal barrier coatings and improve their high-temperature resistance, induction plasma spheroidization (IPS) technology was applied to regulate the structure of YSZ powders in this study. The surface morphology, particle size distribution, phase composition, and internal microstructure of the conventional agglomerated and spheroidized powders were characterized using scanning electron microscopy and focused ion beam analysis methods. The results showed that the microstructure of the powders presented uneven evolution in the induction plasma stream. Due to the existence of the temperature gradient along the radial direction of the powders, the IPS powders consisted of outer dense shells and internal porous cores. The mechanical property of such shell–core structure was analyzed by using the finite elemental simulation method. In addition, coatings were prepared using the IPS powders and the agglomerated powders. The IPS coating showed improved water-cooling thermal cycling resistance compared to the conventional coating.

Surface Pinning of Mn by Oxidation State Control for the Synthesis of Cobalt-Free, Ni-Rich, Core/Shell Structured Cathode Materials.

Motivated by the increasing cost, environmental concerns, and limited availability of Co, researchers are actively seeking alternative cathode materials for lithium-ion batteries. A promising strategy involves structure-modified materials, such as a NiMn core/shell system. This design leverages the high energy density of a Ni-rich core while employing an Mn-rich shell to enhance interfacial stability by suppressing unwanted reactions with the electrolyte. This approach offers improved cycling stability and reduced reliance on Co. However, the interdiffusion of Mn ions between the core and shell remains a significant challenge during synthesis. This work presents a facile approach to address the issue of Mn interdiffusion in core/shell cathode materials. The study demonstrates that partial oxidation of the precursor during the drying stage effectively enhances the Mn oxidation state. This strategy successfully suppresses Mn interdiffusion during subsequent calcination, leading to the preservation of the core/shell architecture in the final cathode material. This optimized structure mitigates interfacial reactions, enhances chemomechanical properties, and reduces crosstalk, a major contributor to rollover failure. This work presents a novel approach for synthesizing high-performance core/shell cathode materials for next-generation lithium-ion batteries.

Linkage among the neutron-skin thickness of 208Pb and nuclear symmetry energy using heavy particle radioactivity

The nuclear symmetry energy (NSE) is a linchpin in deciphering the behavior of matter in a wider domain extending from the characteristics of exotic nuclei to those of neutron stars in the cosmos. Therefore, it is crucial to utilize potential probes to constrain the NSE and its slope parameter L(ρ 0). In this work, we put forth the heavy particle radioactivity (HPR) as a probable bridge among the slope of NSE (L(ρ 0)) and neutron-skin thickness of 208Pb (R skin 208), which serves to put constrain on the L(ρ 0) value. The NSE and its slope parameter are determined from the single nucleon potential of asymmetric nuclear matter exploiting the analytical relationship between these quantities. The isovector/symmetry potential component of the single nucleon potential is derived through HPR for varying R skin 208 by employing the heavy particle/cluster densities and core densities from the relativistic mean field model in conjunction with M3Y nucleon–nucleon interaction. It facilitates in constraining the L(ρ 0) value and neutron skin of finite nuclei using HPR as a linkage, where heavy cluster and core densities of standard Fermi form are considered. The constrained value of L(ρ o ) is 45 ± 8 MeV, which aligns with other estimations derived from nuclear mass measurements, dipole polarizability measurements, and astrophysical data.

Formation of low-mass protostars and their circumstellar disks

Understanding circumstellar disks is of prime importance in astrophysics; however, their birth process remains poorly constrained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often wrapped into a sub-grid model, play a crucial role in disk formation and evolution. This calls for a combined approach in which both the protostar and circumstellar disk are studied in concert. We aim to elucidate the small-scale physics and constrain sub-grid parameters commonly chosen in the literature by resolving the star-disk interaction. We carried out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe the collapse of a turbulent, dense molecular cloud core to stellar densities. We studied the birth of the protostar, the circumstellar disk, and its early evolution ($<6\ yr $ after protostellar formation). Following the second gravitational collapse, the nascent protostar quickly reaches breakup velocity and sheds its surface material, thus forming a hot ($ K $), dense, and highly flared circumstellar disk. The protostar is embedded within the disk such that material can flow without crossing any shock fronts. The circumstellar disk mass quickly exceeds that of the protostar, and its kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, and accretion onto the protostar mainly occurs through material that slides on the disk surface. The polar mass flux is negligible in comparison. The radiative behavior also displays a strong anisotropy, as the polar accretion shock was shown to be supercritical, whereas its equatorial counterpart is subcritical. We also find a remarkable convergence of our results with respect to initial conditions. These results reveal the structure and kinematics in the smallest spatial scales relevant to protostellar and circumstellar disk evolution. They can be used to describe accretion onto regions commonly described by sub-grid models in simulations studying larger-scale physics.

Curved Polymeric Sandwich Composites Subjected to Air Shock: An Experimental Investigation

BackgroundThe vulnerability of polymeric composite sandwich structures in marine applications to air explosions highlights a significant gap in our understanding of the dynamic behavior of the curved sandwich structures, which is essential for design improvements.ObjectiveThis study aims to explore the dynamic response and failure mechanisms of curved sandwich composite panels subjected to air-blast loading, providing insights into their structural integrity under such conditions.MethodsExperiments were performed using laboratory-simulated air shocks generated by a shock tube, employing high-speed photography and digital image correlation to measure deflections on the back surface of the panels. The panels, made with PVC closed-cell foam cores of two densities (H45 and H130), were tested across three curved geometries (radii of 112 mm, 305 mm, and infinity) under various boundary conditions.ResultsFindings indicate an increase in deformation with a decreased radius of curvature under simple support conditions, a trend that reverses under arrested displacement conditions. Moreover, a reduced radius significantly enhances panel strength and resistance to interfacial damage, with the primary failure mode transitioning from core shear cracking to interfacial debonding as core density increases.ConclusionsThe study reveals that the radius of curvature, boundary conditions, and core density significantly affect curved sandwich panels’ dynamic response and performance. Panels with smaller radii and higher core densities exhibit increased strength, though boundary conditions introduce variable effects on deformation behavior.

The Bow Shock and Magnetosheath Responses to Density Depletion Structures

AbstractHot flow anomalies (HFAs) are typical and important foreshock transients characterized by large flow deflection and plasma heating. HFAs can deform the Earth's bow shock by dynamic pressure perturbation resulting in disturbance in the magnetosphere and ionosphere. Traditionally, HFAs are believed to be associated with discontinuities. But recently, HFA‐like structures were simulated by a magnetohydrodynamics (MHD) model without the discontinuity prerequisite. In this study, three HFA‐like structures are shown to present the MHD formation mechanism. Multi‐points observation by the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission tracks the formation of an HFA from a density depletion upstream. HFAs with high‐ or low‐ density cores are observed by the Magnetospheric Multiscale mission in the flank region. The comparisons of the observation and their simulation show general agreement, particularly in the presence of a core with strong heating and velocity deflection, and two compression regions (shocks) with clear maxima in the ram pressure with a strongly inclined normal boundary at the leading edge and moderately inclined at the trailing edge. Agreement is better when the MHD simulations used a transient change to quasi‐parallel solar wind magnetic field during the events.

Multiple Outflows around a Single Protostar IRAS 15398−3359

We present the results of our mosaic observations of a single Class 0 protostar IRAS 15398−3359 with the Atacama Compact Array in the CO J = 2–1 line. The new observations covering a ∼2′ square region reveal elongated redshifted and blueshifted components, which are located at distances of ∼30″–75″ on the northern and southern sides of the protostar, respectively, in addition to the previously observed primary and secondary outflows. These elongated components exhibit Hubble-law-like velocity structures, i.e., an increase of velocity with increasing distance from the protostar, suggesting that they comprise the third outflow associated with the protostar. Besides, a new redshifted component is detected at radii of ∼40″–75″ on the northwestern side of the protostar. This redshifted component also exhibits a Hubble-law-like velocity profile, which could be a counterpart of the secondary outflow mostly detected at blueshifted velocities in a previous study. The three outflows are all misaligned by ∼20°–90°, and the dynamical timescale of the primary outflow is shorter than those of the other outflows, approximately by an order of magnitude. These facts hint that the outflow launch direction has significantly changed with time. The outflow direction may change if the rotational axis and the magnetic field are misaligned or if the dense core is turbulent. We favor the second scenario as the origin of the multiple outflows in IRAS 15398−3359, based on a comparison between the observational results and numerical simulations.

Reassessment of Birch's Law on hcp‐Fe From Ultrasonic Sound Velocity Measurement and Implications on the Velocity Profiles of Earth's Inner Core

AbstractWe performed in situ X‐ray diffraction and ultrasonic sound velocity measurements on hcp‐Fe up to 15 GPa, 873 K in a multi‐anvil apparatus. The elastic moduli and their pressure and temperature derivatives were determined by fitting the velocity and density data to the third‐order finite strain equations, yielding KS0 = 169.0(57) GPa, KS0′ = 5.4(6), (∂KS/∂T)P = −0.031(3) GPa/K, G0 = 104.5(27) GPa, G0′ = 1.7(2), (∂G/∂T)P = −0.060(2) GPa/K. Within the experimental P‐T range, we find significant temperature effect on the density‐velocity (ρ − VP or S) relations and caution the use of the temperature‐independent Birch's law for extrapolation to core conditions. Furthermore, temperature‐induced velocity decrease is more significant in VS than in VP, offering a possible explanation for the high Poisson's ratio in the core. Extrapolations based on our results together with previous experimental data suggest that VP of hcp‐Fe aligns with PREM at Earth's core conditions, while Vs and density are approximately 10% and 2.7% higher than PREM, respectively.

21 cm Intensity Mapping with the DSA-2000

Line-intensity mapping is a promising probe of the Universe’s large-scale structure. We explore the sensitivity of the DSA-2000, a forthcoming array consisting of over 2000 dishes, to the statistical power spectrum of neutral hydrogen’s 21 cm emission line. These measurements would reveal the distribution of neutral hydrogen throughout the near-redshift Universe without necessitating resolving individual sources. The success of these measurements relies on the instrument’s sensitivity and resilience to systematics. We show that the DSA-2000 will have the sensitivity needed to detect the 21 cm power spectrum at z ≈ 0.5 and across power spectrum modes of 0.03–35.12 h Mpc−1 with 0.1 h Mpc−1 resolution. We find that supplementing the nominal array design with a dense core of 200 antennas will expand its sensitivity at low power spectrum modes and enable measurement of Baryon Acoustic Oscillations. Finally, we present a qualitative discussion of the DSA-2000's unique resilience to sources of systematic error that can preclude 21 cm intensity mapping.

Age-related upregulation of dense core vesicles in the central inferior colliculus.

Presbycusis is one of the most prevalent disabilities in aged populations of industrialized countries. As we age less excitation reaches the central auditory system from the periphery. To compensate, the central auditory system [e.g., the inferior colliculus (IC)], downregulates GABAergic inhibition to maintain homeostatic balance. However, the continued downregulation of GABA in the IC causes a disruption in temporal precision related to presbycusis. Many studies of age-related changes to neurotransmission in the IC have therefore focused on GABAergic systems. However, we have discovered that dense core vesicles (DCVs) are significantly upregulated with age in the IC. DCVs can carry neuropeptides, co-transmitters, neurotrophic factors, and proteins destined for the presynaptic zone to participate in synaptogenesis. We used immuno transmission electron microscopy across four age groups (3-month; 19-month; 24-month; and 28-month) of Fisher Brown Norway rats to examine the ultrastructure of DCVs in the IC. Tissue was stained post-embedding for GABA immunoreactivity. DCVs were characterized by diameter and by the neurochemical profile (GABAergic/non-GABAergic) of their location (bouton, axon, soma, and dendrite). Our data was collected across the dorsolateral to ventromedial axis of the central IC. After quantification, we had three primary findings. First, the age-related increase of DCVs occurred most robustly in non-GABAergic dendrites in the middle and low frequency regions of the central IC during middle age. Second, the likelihood of a bouton having more than one DCV increased with age. Lastly, although there was an age-related loss of terminals throughout the IC, the proportion of terminals that contained at least one DCV did not decline. We interpret this finding to mean that terminals carrying proteins packaged in DCVs are spared with age. Several recent studies have demonstrated a role for neuropeptides in the IC in defining cell types and regulating inhibitory and excitatory neurotransmission. Given the age-related increase of DCVs in the IC, it will be critical that future studies determine whether (1) specific neuropeptides are altered with age in the IC and (2) if these neuropeptides contribute to the loss of inhibition and/or increase of excitability that occurs during presbycusis and tinnitus.

Force and wear prediction model of disc cutter under compression shear failure mode based on dense core–cavity expansion theory (U-713)

Calculating disc cutter wear and predicting wear life are long-standing issues affecting the efficiency and cost of tunnel boring machines (TBMs). During the TBM excavation process, the wear of the disc cutter is a comprehensive outcome of the interaction between the tool and rock. Studying the mechanisms of tool rock breaking and wear can assist in developing a more precise model for predicting cutter wear. Therefore, based on the rock-breaking and wear mechanisms of a cutter, this study developed a model for predicting the cutter wear rate and life. The model is based on the theory of dense core–cavity expansion combined with the motion state of a cutter. First, the TBM excavation process and rock-breaking mechanism of a cutter were analyzed in detail. A cutting force model under the compression shear failure mode based on the dense core–cavity expansion theory was established. Based on the force model, a prediction model for the wear rate and life of the disc cutter was established, considering the working characteristics and wear mechanism. Furthermore, the impact of penetration on the prediction model was investigated. In addition, to demonstrate the practicality of the method, this study conducted a comprehensive examination using engineering examples. The results showed that the average difference in the cutter average wear rate using the developed model was less than 3% compared with the actual engineering result. In addition, the average difference in the wear life rate was less than 5%. Finally, the developed prediction method was compared with other models. The wear rate fitting accuracy was improved by 4.91–10.85% and the wear life fitting accuracy was improved by 5.11–12.19% by the developed method. This improvement confirms the reasonableness and reliability of the method. This method can estimate the wear rate and lifespan of a cutter more accurately and reliably than other methods, providing a practical tool to TBM engineers to make informed decisions and optimize tool replacement programs.

Investigations of Massive Filaments and Star Formation (INFANT). I. Core Identification and Core Mass Function

Filamentary structures are ubiquitously found in high-mass star-forming clouds. To investigate the relationship between filaments and star formation, we carry out the INFANT (Investigations of Massive Filaments and Sar Formation) survey, a multiscale, multiwavelength survey of massive filamentary clouds with Atacama Large Millimeter/submillimeter Array (ALMA) band 3/band 6 and Very Large Array K band. In this first paper, we present the ALMA band 6 continuum observations toward a sample of eight high-mass star-forming filaments. We covered each target with an approximately rectangular mosaic field of view with two 12 m array configurations, achieving an angular resolution of ∼0.″6 (2700 au at 4.5 kpc) and a continuum rms of ∼0.1 mJy beam−1 (∼0.06 M ⊙ in gas mass assuming 15 K). We identify cores using the getsf and astrodendro and find the former is more robust in terms of both identification and measuring flux densities. We identify in total 183 dense cores (15–36 cores in each cloud) and classify their star formation states via outflow and warm gas tracers. The protostellar cores are statistically more massive than the prestellar cores, possibly indicating further accretion onto cores after the formation of protostars. For the high-mass end ( Mcore > 1.5 M ⊙) of the core mass function (CMF) we derive a power-law index of −1.15 ± 0.12 for the whole sample and −1.70 ± 0.25 for the prestellar population. We also find a steepening trend in CMF with cloud evolution (−0.89 ± 0.15 for the young group versus. −1.44 ± 0.25 for the evolved group) and discuss its implications for cluster formation.

Accretion discs onto supermassive compact objects: A portal to dark matter physics in active galaxies

Context. The study of the physics of the accretion discs that develop around supermassive black hole (BH) candidates provides essential theoretical tools to test their nature. Aims. Here, we study the accretion flow and associated emission using generalised α-discs accreting onto horizonless dark compact objects in order to make comparisons with the traditional BH scenario. The BH alternative proposed here consists in a dense and highly degenerate core made of fermionic dark matter (DM) and surrounded by a more diluted DM halo. This dense core–diluted halo DM configuration is a solution of Einstein’s equation of general relativity (GR) in spherical symmetry, which naturally arises once the quantum nature of the DM fermions is duly accounted for. Methods. The methodology followed in this work consists in first generalising the theory of α-discs to work in the presence of regular and horizonless compact objects, and then applying it to the case of core–halo DM profiles typical of active-like galaxies. Results. The fact that the compactness of the dense and transparent DM core scales with particle mass allows the following key findings of this work: (i) There is always a given core compacity – corresponding particle mass – that produces a luminosity spectrum that is almost indistinguishable from that of a Schwarzschild BH of the same mass as the DM core. (ii) The disc can enter deep inside the non-rotating DM core, allowing accretion-powered efficiencies of as high as 28%, which is comparable to that of a highly rotating Kerr BH. Conclusions. These results, together with the existence of a critical DM core mass of collapse into a supermassive BH, open new avenues of research for two seemingly unrelated topics: AGN phenomenology and dark matter physics.

Developing a lightweight hybrid profile concept with a steel shell and polymeric lattice core for optimal mechanical performance

The building industry needs new design approaches to minimize resource consumption and negative environmental impacts. This study proposes a lightweight hybrid profile that combines a thin steel shell and a polymeric lattice core. The core density and internal structure variation possibilities control the slender steel profile’s load-bearing capacity and optimize the hybrid structure’s weight because of a synergy of the composite section components. The test campaign employs a 3D printing technology for prototyping the lattice core because the manufacturing preciseness (including the internal stiffener structure) is vital for structural optimization and developing adequate numerical models. A straightforward example illustrates the proposed concept. Lateral compression tests on 100 mm long fragments of the slender rectangular hollow section (RHS) 200/100/4 mm (height/width/thickness) profile prove the mechanical efficiency of the proposed hybrid section concept. Reducing the RHS fragment length ensures the experimental identification of the stiffening mechanism in the polymeric insert using a digital image correlation (DIC) technique and simplifies the numerical model. The 3D-printed lattice polymeric core added only 28% to the weight of the hybrid RHS fragment and increased its mechanical resistance twice compared to the reference empty shell fragments. This effect is equivalent to raising the profile thickness from 4 mm to 6 mm, resulting in a 1.5-times increase in weight. Using recycled plastics, adhesive connecting the inserts, and optimizing the internal geometry of the core stiffeners, depending on the loading conditions, may further increase the economic benefits of the proposed hybrid profile concept.

Ultrastructure of silk threads of the water spider Argyroneta aquatica (Clerck, 1757) (Araneae, Cybeidae) in comparison with that of some mites

Silk of the water spider Argyroneta aquatica (Clerck, 1757) was obtained in the laboratory in the form of a capturing web irrespective of the formation of a diving bell and egg cocoon. Silk threads were examined by light microscopy, scanning (SEM), and transmission electron microscopy (TEM) as well as by atomic force (AFM) microscopy. Based on the diameter and internal organization, the silk threads have been divided into five types—a-, b-, c-, d-, and e-types interlaced freely in the thread bundles taken for examinations. Threads of all types are infinitely long, non-branched, round in shape, uniform in width through their course, and rarely found to be ruptured. Threads of the a-type are mostly straight, up to 1,000 nm in diameter, and composed of a fibrillary wall enveloping an electron-dense vacuolated core, which may be occasionally absent. The wall may also become lost, leaving a single core substance surrounded by a slightly wrinkled double membrane. Threads of the b-, c-, and d-types are organized nearly identical, being composed of a fine granular electron-light uniform material enveloped by a fine membrane. The diameter of these threads varies from max. 500 nm in the b-type and 120 nm in the c-type to around 50 nm in the d-type. Threads of these types are more convoluted and more numerous than threads of the a-type. Threads of the last kind, the e-type, occur rarely and are significantly larger with a diameter of around 3.5–4.5 µm. They possess the layered membranous wall surrounding a uniformly dense core. The silk of the water mites Limnochares aquatica (L., 1758) and Limnesia maculata (O.F. Müller, 1776) is composed of threads of only one type that closely corresponded to the a-type threads of A. aquatica. Conversely, the silk of the two-spotted spider mite Tetranychus urticae (C.L. Koch, 1836) consists of threads highly correlated with the d-type threads of A. aquatica. This finding shows that in different phylogenetic lineages of arachnids, the mechanisms of silk production are quite similar.

Experimental AC loss study on REBCO coil assemblies coupled with an iron cylinder

In high-temperature superconducting (HTS) power devices, the presence of iron cores changes the magnetic field profile around the HTS coil windings, potentially affecting their AC loss characteristics. AC loss measurements for HTS coil windings coupled with an iron core using the electrical method can lead to a significant error, owing to the indirect estimation of the iron core loss through using a copper test coil. To investigate the cause of the experimental error and the influence of an iron core on coil AC losses, transport AC losses of REBCO double pancake coil (DPC) assemblies coupled with an iron cylinder were measured. A 40-turn 1DPC and an 80-turn 2DPC assembly wound with 4 mm SuperPower wire were employed in the measurements. To ensure the same iron core loss using the HTS coil assembly and the copper coil, 2D finite element method simulations were conducted iteratively to design the iron core and the copper coil to get the same local magnetic field distributions in the designed iron core for the two cases. The main cause of the error is due to the difference in local magnetic flux densities in the iron core generated by the HTS coil assembly and the copper coil even when the ampere-turns of the coils are identical. We showed that the simulation-guided measurement method can assure accurate AC loss measurement in the HTS coil assemblies coupled with iron cores. Compared with the AC losses in the 1DPC and 2DPC coil assemblies without the iron cylinder, the presence of the iron cylinder significantly increases the coil losses. Frequency dependence is observed in the coil AC losses of the 1DPC and 2DPC assemblies when coupled with the iron cylinder. This is due to the eddy current induced in the iron cylinder generating a magnetic field, which influences the coil AC loss.

High-throughput assay for regulated secretion of neuropeptides in mouse and human neurons

Neuropeptides are the largest group of chemical signals in the brain. More than 100 different neuropeptides modulate various brain functions, and their dysregulation has been associated with neurological disorders. Neuropeptides are packed into dense core vesicles (DCVs), which fuse with the plasma membrane in a calcium-dependent manner. Here, we describe a novel high-throughput assay for DCV exocytosis using a chimera of Nanoluc luciferase and the DCV-cargo neuropeptide Y (NPY). The NPY-Nanoluc reporter colocalized with endogenous DCV markers in all neurons and little mis-localization to other cellular compartments. NPY-Nanoluc reported DCV exocytosis in both rodent and iPSC-derived human neurons, with similar depolarization-, Ca2+-, RAB3- and STXBP1/MUNC18-dependence as low throughput assays. Moreover, NPY-Nanoluc accurately reported modulation of DCV exocytosis by known modulators diacylglycerol-analog and Ca2+-channel blocker, and showed a higher assay sensitivity than a widely used single cell low throughput assay. Lastly, we showed that Nanoluc coupled to other secretory markers reports on constitutive secretion. In conclusion, the NPY-Nanoluc is a sensitive reporter of DCV exocytosis in mammalian neurons, suitable for pharmacological and genomic screening for DCV exocytosis genes and for mechanism-based treatments for CNS disorders.