Black Scales Research Articles

Analytical Models for Secular Descents in Hierarchical Triple Systems

Three-body systems are prevalent in nature, from planetary to stellar to supermassive black hole scales. In a hierarchical triple system, oscillations of the inner orbit’s eccentricity and inclination can be induced on secular timescales. Over many cycles, the octupole-level terms in the secular equations of motion can drive the system to extremely high eccentricities via the eccentric Kozai–Lidov (EKL) mechanism. The overall decrease in the inner orbit’s pericenter distance has potentially dramatic effects for realistic systems, such as tidal disruption events. We present an analytical approximation in the test-particle limit to describe individual stepwise increases in eccentricity of the inner orbit. A second approximation, also in the test-particle limit, is obtained by integrating the equations of motion and calibrating to numerical simulations to estimate the overall octupole-level time evolution of the eccentricity. The latter approach is then extended beyond the test particle to the general case. The three novel analytical approximations are compared to numerical solutions to show that the models accurately describe the form and timescale of the secular descent from large distances to a close-encounter distance (e.g., the Roche limit). By circumventing the need for numerical simulations to obtain the long-term behavior, these approximations can be used to readily estimate properties of close encounters and descent timescales for populations of systems. We demonstrate this by calculating rates of EKL-driven migration for Hot Jupiters in stellar binaries.

Effects of Acid Pre-Treatment on Removal of Organic and Inorganic Substances from Black Tilapia Bones and Scales

Fish bones and scales are good sources of gelatin. However, high mineral content in bones and scales often lead to low quality gelatin with high percentage of ash. Therefore, pre-treatment with acid prior to gelatin extraction is necessary. Black tilapia (Oreochromis niloticus) bones and scales were subjected to Hydrochloric (HCl) acid of 0.6 M to 1.4 M for 0 to 32 hr. The suitable pre-treatment conditions were determined using percentage of ash removed and loss of protein from the samples. Results obtained indicate, 99.86 % and 99.84 % of ash can be removed from bones and scales, with 1.4 M HCl (32 hr) and 1.0 M HCl (10 hr), respectively. Further analysis with UV-Vis revealed that, excessive protein breakdown starts to occur at 1.0 M (32 hr) and 0.6 M (12 hr), in bones and scales, respectively. The data suggest using pre-treatment conditions lower than the above to avoid protein loss which may lead to low gelatin yield.

Bridging relativistic jets from black hole scales to long-term electromagnetic radiation distances: A moving-mesh general relativistic hydrodynamics code with the HLLC Riemann solver

Relativistic jets accompany the collapse of massive stars, the merger of compact objects, or the accretion of gas in active galactic nuclei. They carry information about the central engine and generate electromagnetic radiation. No self-consistent simulations have been able to follow these jets from their birth at the black hole scale to the Newtonian dissipation phase, making the inference of central engine property through astronomical observations undetermined. We present the general relativistic moving-mesh framework to achieve the continuity of jet simulations throughout space and time. We implement the general relativistic extension for the moving-mesh relativistic hydrodynamic code, , and develop a tetrad formulation to utilize the Harten-Lax-van Leer Contact Riemann solver in the general relativistic moving-mesh code. The new framework is able to trace the radial movement of relativistic jets from central regions where strong gravity holds all the way to distances of jet dissipation. Published by the American Physical Society 2024

Effects of Mn and Cu on descaling of hot-rolled 304L stainless steel in HCl and H2O2 mixtures

Abstract Descaling of stainless-steel black coil is an important step to produce white coil with smooth glossy surface. The AISI 304L black and white coils from a company containing 1.08–1.71Mn and 0.22–0.40Cu (wt%) were used to study the effects of Mn and Cu on descaling rate by potentiodynamic polarization technique at 25 °C. The pickling solutions were 0.5 M HCl and 0.5 M HCl mixed with H2O2 of 0.5, 0.88 and 1.76 M. The polarization curves of black and white coil samples measured in HCl–H2O2 mixture showed no passive range. The descaling rate of black coil oxide scales, and the corrosion potential (E corr) increased with H2O2 concentration. Low-Mn sample, that is 1.08%Mn0.23%Cu sample, showed higher descaling rate than high-Mn samples. No effects of Cu content on the descaling rate were observed. For white coil samples, the descaling rates were almost constant, but pitting on surface was observed. Passive films were eliminated. The corrosion potentials of black and white coil samples increased when adding H2O2 in HCl solution indicating an increase in cathodic reaction due to increase in dissolved oxygen. The corrosion potentials of 1.08%Mn0.23%Cu black and white coil samples were lower than those of high-Mn samples corresponding to less Mn oxide.

The Anatomy and Morphology of Taenitis Willd. ex Sprengel (Monilophytes) in Peninsular Malaysia

The present study investigates the anatomical and morphological characteristics of four Taenitis species sampled from several localities in Peninsular Malaysia, namely Taenitis blechnoides, T. interrupta, T. dimorpha and Taenitis sp. The morphological and anatomical characters were observered with compound and dissecting microscopes, and sliding microtome. The species exhibited varying frond sizes (length and width) and positions of sori. Conversely, all the species showed common short creeping rhizomes with black hairy scales, scales at the base of stipes, U-shaped steles, simple trichome, sclerenchyma cells under the epidermis on stipes and rhizomes, polocytic stomata, and sinuous anticlinal walls. Morphologically, the frond form of Taenitis sp. is distinct from the other Taenitis. Thus, the species could be a new record for ferns in Peninsular Malaysia. However, molecular studies are required to confirm this.

The Complete Genome Sequence of Chrysopelea ornata, Ornate Flying Snake

Chrysopelea ornata, commonly known as the ornate flying snake, is a beautiful and unique species of snake found in Southeast Asia. This snake is famous for its ability to glide from tree to tree. The snake’s body is slender and long, with a characteristic pattern of black and yellow scales that give it a prominent appearance. The significant feature of the ornate flying snake is its ability to glide. This snake launches itself from a high branch and glide up to 100 meters through the air. The snake’s gliding ability is due to its unique physical features, including its elongated ribcage and flattened belly. By flattening its body, the snake can create a greater surface area, allowing it to stay aloft for longer periods. The snake also moves its body in an undulating motion, which generates lift and helps it maintain its balance. It is hunted and smuggled. Here we present you the Whole Genome Sequence of Chrysopelea ornata.

Wrapped M5-branes and AdS5 black holes

We use consistent truncations in supergravity to show that the backreaction of N rotating M5-branes wrapped on a Riemann surface leads to asymptotically AdS5 black hole solutions of 11d supergravity. We discuss the thermodynamic properties of these black holes focusing on their supersymmetric limit. The Bekenstein-Hawking entropy of the supersymmetric black holes scales as N3 and can be reproduced by the superconformal index of the holographically dual 4d mathcal{N} = 1 SCFTs of class mathcal{S} .

Heme protein identified from scaly-foot gastropod can synthesize pyrite (FeS2) nanoparticles.

The scaly-foot gastropod (Chrysomallon squamiferum), which lives in the deep-sea zone of oceans around thermal vents, has a black shell and scales on the foot. Both the black shell and scales contain iron sulfide minerals such as greigite (Fe3S4) and pyrite (FeS2). Although pyrite nanoparticles can be used as materials for solar panels, it is difficult to synthesize stable and spherical nanoparticles in vitro. In this study, we extracted organic molecules that interact with nano-pyrite from the shell of the scaly-foot gastropod to develop a low-cost, eco-friendly method for pyrite nanoparticles synthesis. Myoglobin (csMG), a heme protein, was identified in the iron sulfide layer of the shell. We purified recombinant csMG (r-csMG) and demonstrated that r-csMG helped in the conversion of ferric ions, sulfide ions and sulfur into spherical shaped pyrite nanoparticles at 80°C. To reduce the effort and cost of production, we showed that commercially available myoglobin from Equus caballus (ecMG) also induced the in vitro synthesis of pyrite nanoparticles. Using structure-function experiments with digested peptides, we highlighted that the amino acid sequence of r-csMG peptides controlled the spherical shape of the nanoparticle while the hemin molecules, which the peptides interacted with, maintained the size of nanoparticles. Synthesized pyrite nanoparticles exhibited strong photoluminescence in the visible wavelength region, suggesting its potential application as a photovoltaic solar cell material. These results suggest that materials for solar cells can be produced at low cost and energy under eco-friendly conditions. STATEMENT OF SIGNIFICANCE: Pyrite is a highly promising material for photovoltaic devices because of its excellent optical, electrical, magnetic, and transport properties and high optical absorption coefficient. Almost all current pyrite synthesis methods use organic solvents at high temperature and pressure under reducing conditions. Synthesized pyrite nanoparticles are unstable and are difficult to use in devices. The scaly-foot gastropod can synthesize pyrite nanoparticles in vivo, meaning that pyrite nanoparticles can be generated in an aqueous environment at low temperature. In this study, we demonstrated the synthesis of pyrite nanoparticles using a heme protein identified in the iron sulfide layer of the scaly-foot gastropod shell. These results exemplify how natural products in organisms can inspire the innovation of new technology.

The origin of black and white coloration of the Asian tiger mosquito Aedes albopictus (Diptera: Culicidae).

Micro- and nanostructures of the white and black scales on the tarsi of the mosquito Aedes albopictus are analysed using scanning electron microscopy, transmission electron microscopy, and fluorescence microscopy. Reflectance spectra of the white areas are measured. No clear difference is present in the morphology of micro- and nanostructures of black and white scales in SEM and TEM, but black scales contain a dark pigment. The white colour of the scales has a structural origin. The structural white produced by the micro- and nanostructures of the scales on the tarsi of Ae. albopictus appears bright and is angle-dependent, since the reflected light changes according to the angle detection and according to the tarsus orientation. The optical appearance of the scale system of Ae. albopictus has a complex nature and can be explained by the combination of several effects. Among them, multiple refraction and reflection on the micro- and nanostructures of the scales are mainly responsible for the white appearance. The results suggest that mosquito scales, in addition to their superhydrophobic function, produce structural white. The biological role of white and black patches in mate recognition and defensive behaviour in the mosquitoes of the genus Aedes is hypothesized.

The genetic basis of wing spots in Pieris canidia butterflies

Spots in pierid butterflies and eyespots in nymphalid butterflies are likely non-homologous wing colour pattern elements, yet they share a few features in common. Both develop black scales that depend on the function of the gene spalt, and both might have central signalling cells. This suggests that both pattern elements may be sharing common genetic circuitry. Hundreds of genes have already been associated with the development of nymphalid butterfly eyespot patterns, but the genetic basis of the simpler spot patterns on the wings of pierid butterflies has not been investigated. To facilitate studies of pierid wing patterns, we report a high-quality draft genome assembly for Pieris canidia, the Indian cabbage white. We then conducted transcriptomic analyses of pupal wing tissues sampled from the spot and non-spot regions of P. canidia at 3-6 h post-pupation. A total of 1352 genes were differentially regulated between wing tissues with and without the black spot, including spalt, Krüppel-like factor 10, genes from the Toll, Notch, TGF-β, and FGFR signalling pathways, and several genes involved in the melanin biosynthetic pathway. We identified 14 genes that are up-regulated in both pierid spots and nymphalid eyespots and propose that spots and eyespots share regulatory modules despite their likely independent origins.

Supersoft luminous X-ray sources in galactic nuclei

Context. Tidal disruption events (TDEs) are usually discovered at X-ray or optical wavelengths through their transient nature. A characteristic spectral feature of X-ray detected TDEs is a ‘supersoft’ X-ray emission, not observed in any other extragalactic source, with the exception of a few rapidly variable hyperluminous X-ray sources (HLXs) or supersoft active galactic nuclei (AGN) that are distinguishable by their optical emission. Aims. The goal of our work is to find extragalactic supersoft sources associated with galactic centres. We expect this category to include overlooked TDEs, supersoft AGN, and nuclear HLXs. Finding such sources would allow for the study of extreme regime accretion on different black hole mass scales. Methods. We searched for supersoft X-ray sources (SSSs) by cross-correlating optical and X-ray catalogues to select extragalactic near-nuclear sources and we then filtered for very steep spectra (photon index Γ > 3) and high X-ray luminosities (LX > 1041 erg s−1). Results. With our blind search we retrieved about 60 sources, including 15 previously known supersoft AGN or TDEs, thus demonstrating the efficiency of our selection. Of the remaining sample, 36 sources are optically classified as AGN, although they show steeper-than-usual spectra. The remaining nine previously unknown sources show spectral properties consistent with emission by extremely soft-excess dominated AGN (five sources) or TDEs (four sources). An XMM-Newton follow-up observation of one of these sources confirmed its likely TDE nature. Conclusions. Our work is the first attempt to discover TDEs by their spectral features rather than their variability, and it has been successful in retrieving known TDEs and in discovering new extreme ultrasoft sources, including four new TDE candidates, one of which is confirmed via follow-up observations.

Pollution characteristics of full-scale butterfly valves: Risk assessment of heavy metal release behavior influenced by the bacterial communities and corrosion products

Given that contamination of butterfly valves has not been well understood in drinking water distribution systems (DWDSs), this study aimed to investigate the synergistic adsorption/release effects of microorganisms and corrosives on heavy metals. Results showed that outer layer scales were relatively loose, while hard black inner scales were mainly composed of Fe3O4 and Fe2O3, allowing Ca, As, Cr, Tl, and Pb to accumulate with low-diverse bacteria, primarily Desulfovibrio. Loose black inner layer scales were mainly formed by Fe(OH)3 and Fe(OH)2, enabling Ca, Cr, and Pb to accumulate with high-diverse bacteria, notably Desulfovibrio, Xanthobacteraceae, and Gallionellaceae. Metals involved in the metabolic activity of bacteria showed a negative correlation with these bacteria. Metals complexed and precipitated extracellularly in bacteria exhibited a positive correlation with these bacteria. Individual Pollution Factor (ICF), Global Pollution Factor (GCF), and Risk Assessment Code (RAC) demonstrated high bio-availability risks for Cd, especially in loose deposits with significant mobility.

Deciphering the extreme X-ray variability of the nuclear transient eRASSt J045650.3−203750

Context. During its all-sky survey, the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spectrum-Roentgen-Gamma (SRG) observatory has uncovered a growing number of X-ray transients associated with the nuclei of quiescent galaxies. Benefitting from its large field of view and excellent sensitivity, the eROSITA window into time-domain X-ray astrophysics yields a valuable sample of X-ray selected nuclear transients. Multi-wavelength follow-up enables us to gain new insights into understanding the nature and emission mechanism of these phenomena. Aims. We present the results of a detailed multi-wavelength analysis of an exceptional repeating X-ray nuclear transient, eRASSt J045650.3−203750 (hereafter J0456−20), uncovered by SRG/eROSITA in a quiescent galaxy at a redshift of z ∼ 0.077. We aim to understand the radiation mechanism at different luminosity states of J0456−20, and provide further evidence that similar accretion processes are at work for black hole accretion systems at different black hole mass scales. Methods. We describe our temporal analysis, which addressed both the long- and short-term variability of J0456−20. A detailed X-ray spectral analysis was performed to investigate the X-ray emission mechanism. Results. Our main findings are that (1) J0456−20 cycles through four distinctive phases defined based on its X-ray variability: an X-ray rising phase leading to an X-ray plateau phase that lasts for abouttwo months. This is terminated by a rapid X-ray flux drop phase during which the X-ray flux can drop drastically by more than a factor of 100 within one week, followed by an X-ray faint state for about two months before the X-ray rising phase starts again. (2) The X-ray spectra are generally soft in the rising phase, with a photon index ≳3.0, and they become harder as the X-ray flux increases. There is evidence of a multi-colour disk with a temperature of Tin ∼ 70 eV in the inner region at the beginning of the X-ray rising phase. The high-quality XMM-Newton data suggest that a warm and hot corona might cause the X-ray emission through inverse Comptonisation of soft disk seed photons during the plateau phase and at the bright end of the rising phase. (3) J0456−20 shows only moderate UV variability and no significant optical variability above the host galaxy level. Optical spectra taken at different X-ray phases are constant in time and consistent with a typical quiescent galaxy with no indication of emission lines. (4) Radio emission is (as yet) only detected in the X-ray plateau phase and rapidly declines on a timescale of two weeks. Conclusions. J0456−20 is likely a repeating nuclear transient with a tentative recurrence time of ∼223 days. It is a new member of this rare class. We discuss several possibilities to explain the observational properties of J0456−20. We currently favour a repeating partial tidal disruption event as the most likely scenario. The long-term X-ray evolution is explained as a transition between a thermal disk-dominated soft state and a steep power-law state. This implies that the corona can be formed within a few months and is destroyed within a few weeks.

Survey of insect-pests of citrus crop in Eritrea

Citrus is the main fruit crop in Eritrea with the main citrus species being orange, lemon and mandarin that are produced in 2064, 328 and 17 ha, respectively. The production and productivity of these fruit crops are affected by several pests. Citrus pest survey was conducted in major citrus growing regions of the country with the objectives to assess the type of citrus insect-pests in the different areas, study the natural enemies of the citrus pests and assess the nature of pest damage on the fruit crop. Pest assessments and counts by species were done using hand lenses under field condition and microscope in laboratory. The result of the study showed that citrus is affected by 21 different species of arthropods out of which 19 are insect species and the remaining 2 species are Acarina (mites). The insect pests cause citrus tree damage at different stage and on different parts of the tree such as leaves, stem, fruit and root. Of the 21 species, six are major pest and the remaining 15 species are minor pests. The six important pests are leaf miner, red scale, black scale, fruit fly, whitefly and red spider mites. Leaf miner, fruit fly and red spider mites were observed in all citrus production areas while the remaining three species were recorded in limited areas. Black and red scales incidence and severity were high in Hamelmalo, Elabered, Alla, and Durfo. Fruit fly is the main pest of citrus throughout the fruit producing areas of the country, threatening its production and cause 20-40 percent fruit dropping and rotting.

Size-related changes and chemical basis of melanin-based body coloration in the amphisbaenian Trogonophis wiegmanni

Abstract Melanin is a fundamental pigment in animal coloration as it is involved in many different adaptive functions such as signaling or thermoregulation. Two forms of melanin are known to produce different colors (eumelanin: black; pheomelanin: yellow or brown). Here, we explored whether there were intersexual differences and/or size-related changes in melanization of the amphisbaenian Trogonophis wiegmanni, a fossorial species with a characteristic black and yellow color pattern of scales. We found a clear effect of body length, but not of sex, on the levels of melanization, which was also dependent on the body region; the proportion of melanin-dependent blackish coloration increased with body length in the dorsum, but decreased with body length in the ventral belly area. We also studied the chemical basis of this coloration using Raman spectroscopy and found that eumelanin was present in both black and yellow scales, but pheomelanin was not found in yellow scales, suggesting that this yellow coloration is caused by the reduction of eumelanin or dispersion of melanosomes and/or perhaps by other pigments.

Effect of hydrocarbon condensation on fouling and heat exchange efficiency in EGR cooler

Based on the self-established experiment and test platform and evaluation system, we studied the effects of hydrocarbon condensation on mass, hydrophilicity, color, and micromorphology of fouling and heat transfer efficiency in exhaust gas recirculation (EGR) coolers. The results show that hydrocarbon condensation converts low mass, hydrophobic, solid black, and fluffy scales into larger mass, hydrophilic, white and yellow, and compact scales of fouling. When Total Hydrocarbons (THC) are 590 ppmC, 411 ppmC, and 359 ppmC, the temperatures to the demarcation points of the rapid condensation enhancement and stability stage are 100 °C, 120 °C, and 135 °C, respectively. However, when the temperature exceeds 160 °C, hydrocarbons' condensation is substantially suppressed, and the heat exchange efficiency is the worst. Hydrocarbons condensation will increase the fouling density, improving the heat exchange efficiency; the highest heat exchange efficiency will be achieved when the condensation is stable. Hydrocarbon and particulate matter (PM) together determine the composition and structure of the fouling, which in turn determines the heat transfer efficiency.

The Broad Line Region and Black Hole Mass of NGC 4151

We present a reanalysis of reverberation mapping data from 2005 for the Seyfert galaxy NGC 4151, supplemented with additional data from the literature to constrain the continuum variations over a significantly longer baseline than the original monitoring program. Modeling of the continuum light curve and the velocity-resolved variations across the Hβ emission line constrains the geometry and kinematics of the broad line region (BLR). The BLR is well described by a very thick disk with similar opening angle (θ o ≈ 57°) and inclination angle (θ i ≈ 58°), suggesting that our sight line toward the innermost central engine skims just above the surface of the BLR. The inclination is consistent with constraints from geometric modeling of the narrow-line region, and the similarity between the inclination and opening angles is intriguing given previous studies of NGC 4151 that suggest BLR gas has been observed temporarily eclipsing the X-ray source. The BLR kinematics are dominated by eccentric bound orbits, with ∼10% of the orbits preferring near-circular motions. With the BLR geometry and kinematics constrained, the models provide an independent and direct black hole mass measurement of or M ⊙, which is in good agreement with mass measurements from stellar dynamical modeling and gas dynamical modeling. NGC 4151 is one of the few nearby broad-lined Seyferts where the black hole mass may be measured via multiple independent techniques, and it provides an important test case for investigating potential systematics that could affect the black hole mass scales used in the local universe and for high-redshift quasars.

Toward Red Color Display via Step-By-Step Scheme Design in Particle Activation Stage for Three-Color Electrophoretic Displays

Red particles are the basis of red color display in a three-color electrophoretic display, but driving voltage of red particles overlaps with black gray scales, resulting in a low red saturation and poor display effect. In order to improve the red saturation, a step-by-step driving scheme was proposed with an optimized in the activation stage, which is a part of a driving waveform. Firstly, Stokes law and electrophoretic law were used to analyze and calculate overall driving wave-form, and a positive pulse in activation stage was modulated into a mixture of +3 V and +15 V. Then, mixing duration ratio of +3 V and +15 V was adjusted to improve the activity of red particles. Finally, the number of pulse cycles of the driving waveform in activation stage were optimized to reduce viscous force of red particles. Experimental results showed that compared with ordinary three-color Electrophoretic Displays driving waveform, the proposed driving waveform increased red saturation by 12.915%.

Wing scale patterns of Hypolimnas bolina (Linnaeus, 1758) (Lepidoptera: Nymphalidae)

Hypolimnas bolina (L), exhibit a stunningly bright and lustrous colour wing patches. The present study is focused on the variety of pigmented scales that cover the wings of H. bolina. A total of 128 different types of scales (white, brown, blue as well as black scales) were investigated, which includes 63 morphologically different types of scales on the dorsal part and 65 scales from ventral side. For the analysis the scales are taken from the black and violet portion of dorsal part and brown and white colored patches in ventral region. Micrometry of scales on the dorsal side showed a length range of about 86.6 to 102.4? and width range of 63 to 78.8?. Dimension analysis of ventral region range from 86.6 to 106.3? in length and width of 66.8 to 86.6?. The shape and distribution of scale depends on their exact location on the wing which are responsible for boggling pattern and brilliant visual appearance.

A phylogenetic and morphological study of the Tectariafuscipes group (Tectariaceae), with description of a new species.

The fern species Tectariafuscipes and morphologically similar species, which are common in tropical and subtropical mainland Asia, constitute a taxonomically confusing group. To better understand species boundaries and relationships within the T.fuscipes group, we conducted phylogenetic analyses of five plastid regions and morphological observations of herbarium specimens and living plants. As a result, we produced a generally well-resolved phylogeny of the T.fuscipes group and related species in Asia. The phylogenetic analyses supported the monophyly of the T.fuscipes group, which includes T.dissecta, T.fuscipes, T.ingens, T.paradoxa, T.setulosa, T.subfuscipes, T.subsageniacea and a new species, but excludes T.kusukusensis. However, T.fuscipes, T.subfuscipes and T.subsageniacea are almost indistinguishable in morphology, which form a complex characterised by the black linear-lanceolate stipe scales. The new species found in southern China and Vietnam is described here as T.fungii. It is similar to the T.fuscipes complex and T.kusukusensis, but differs from the former mainly by its brown-castaneous lanceolate stipe scales and from the latter by having nearly hairless laminae (versus frond axes abaxially bearing copious hairs).