Clear Bands Research Articles

Topological signatures of triply degenerate fermions in Heusler alloys: an ab initio study

Triply degenerate nodal point (TP) fermions, lacking elementary particle counterparts, have been theoretically anticipated as quasiparticle excitations near specific band crossing points constrained by distinct space-group symmetries instead of Lorentz invariance. Here, based onfirst-principlescalculations and symmetry analysis, we demonstrate the presence of TP fermions in Heusler alloys. Furthermore, we predict that these Heusler alloys are dynamically stable, exhibiting TP fermions along four distinctC3axes in the F-43m space group. We show thatα-LiCaPdSb harbours peculiar Fermi arcs and surface states on the (111) and (001) crystal facets, owing to the coexistence of threefold rotational and time reversal symmetry. More interestingly, a modest tensile strain can increase the distance of fermions along the Γ-Lhigh symmetric line by as much as 21.10%, which give rise to measurable Fermi arcs. Furthermore, we investigate non-trivial topological insulator phase inβ-LiCaPdSb, by changing the chemical environment through placing transition metal atoms at various Wyckoff positions. Theβ-LiCaPdSb harbour a semi-metallic nature, and by breaking cubic symmetry, it undergoes a transition from semi-metal to a non-trivial topological insulator. In addition, for the first time, rare-earth LaPtBi half-Heusler alloy is examined under strain to uncover multiple band inversions associated with the TP fermionic phase. The observed multiple band inversion is entirely unaffected by spin-orbit coupling. We show that the LaPtBi compound hosts TP fermions, which are linked to aZ2topological invariant. Remarkably, with clear band crossings and multiple band inversion, we point out the possibilities of the LaPtBi for displaying a rich topological phase diagram. Our work provides a prototype material platform for experimental detection through angle-resolved photoemission spectroscopy or scanning tunnelling spectroscopy and practical spintronic applications.

Genetic diversity and fingerprinting of Elaeagnus angustifolia based on SSR molecular markers

DNA fingerprinting can reveal the genetic diversity of Elaeagnus angustifolia germplasm resources and clarify the source and genetic background of E. angustifolia germplasm, which are the preconditions for the breeding of new varieties, the identification and protection of germplasm resources, and the comprehensive development of the E. angustifolia industry considering both ecological and economic benefits. We employed 11 pairs of primers with high polymorphism, clear bands, and high reproducibility to analyze the genetic diversity of 150 E. angustifolia germplasm accessions from Gansu and Beijing by the simple sequence repeat (SSR) molecular markers. We then employed the unweighted pair-group method with arithmetic means (UPGMA) to perform the cluster analysis based on genetic distance and analyzed the genetic structure of the 150 germplasm accessions based on a Bayesian model in Structure v2.3.3. The genetic diversity analysis revealed the mean number of alleles (Na) of 7.636 4, the mean number of effective alleles (Ne) of 2.832 6, the mean Shannon genetic diversity index (I) of 1.178 1, the mean Nei's gene diversity index (H) of 0.582 1, the mean observed heterozygosity (Ho) of 0.489 9, the mean expected heterozygosity (He) of 0.584 0, the mean polymorphism information content (PIC) of 0.535 4, and the mean genetic similarity (GS) of 0.831 5. These results suggested that the E. angustifolia germplasm resources we studied exhibited significant genetic differences and rich genetic diversity. The cluster analysis revealed that the tested materials can be classified into 3 groups, with the main genetic distance (GD) of 0.422 9. The clustering results were not completely consistent with the geographic origin. The population structure analysis classified the germplasm accessions into 2 populations. We used 8 pairs of primers with high PIC to construct the fingerprints of 150 E. angustifolia germplasm accessions. The present study successfully constructs the DNA fingerprints and clarified the genetic relationship of the E. angustifolia germplasm resources in Gansu and Beijing, providing a theoretical basis for germplasm resource identification, breeding of elite varieties, application in gardening, and molecular-assisted breeding of E. angustifolia.

Development of a Multiplex Polymerase Chain Reaction Assay for Detecting Five Previously Unreported Papaya Viruses for Quarantine Purposes in Korea

There are concerns about the introduction and spread of plant pests and pathogens with globalization and climate change. As commercial control agents have not been developed for plant viruses, it is important to prevent virus spread. In this study, we developed a multiplex polymerase chain reaction (PCR) detection method to rapidly diagnose and control three DNA (papaya golden mosaic virus, Lindernia anagallis yellow vein virus, and melon chlorotic leaf curl virus) and two RNA (papaya leaf distortion mosaic virus and lettuce chlorosis virus) viruses that infect papaya. Specific primer sets were designed for the virus coat protein. Performing PCR, clear bands were observed with no non-specific reaction. Our multiplex PCR method can simultaneously detect small amounts of DNA/RNA to diagnose five viruses infecting papaya and prevent the spread of the virus.

Physiological alterations and genotoxic damage under combined aluminum and cadmium treatments in Bryophyllum daigremontianum clones.

Cadmium (Cd) is one of the most important stress factors in plants, with its high mobility in soils, ease of uptake by plants and toxicity at low concentrations. Aluminum (Al) is another phytotoxic metal, the accumulation of which is a crucial agricultural complication for plants, especially in acidic soils. In this study, Bryophyllum daigremontianum clone plantlets were obtained from bulbiferous spurs of a mother plant and separated into four different groups and watered with Hoagland solution and mixtures containing 0, 50, 100, and 200 µM of AlCl3 and CdCl2 each for 75 days. Control groups were maintained under the same conditions without Al and Cd treatment. To simulate acidic soil conditions typical of environments where Al toxicity is prevalent, the soil pH was adjusted to 4.5 by spraying the sulphuric acid (0.2%) with 2-day intervals after each irrigation day. After harvesting, growth parameters such as shoot length and thickness, root, shoot and leaf fresh and dry weights were measured, along with physiological parameters like mineral nutrient status, total protein, and photosynthetic pigment concentrations (chlorophyll a, b, a/b, total chlorophyll, and carotenoid) in both control and experimental groups of B. daigremontianum clones. In response to Al and Cd applications, the plant height, shoot thickness and carotenoid levels were declined, whereas the increments were found in leaf/shoot/root fresh weight, root dry weight, and total protein content. Moreover, differences in genomic alterations were investigated using 21 ISSR and 19 RAPD markers, which both have been used extensively as genetic markers to specify phylogenetic relationships among different cultivars as well as stress-dependent genetic alterations. RAPD primers were used due to their arbitrary sequences and the unknown genome sequence of the plant material used. In contrast, ISSR primers were preferred for a genome-wide genotoxic effect scan via non-arbitrary and more common genetic markers. Distinct types of band polymorphisms detected via RAPD and ISSR markers include band loss, and new band formation under a combination of Al and Cd stress. 17 ISSR and 14 RAPD primers generated clear electrophoretic bands. The study revealed that combined application of Al and Cd affect B. daigremontianum clones in terms of growth, physiology and genotoxicity related to the increasing concentrations.

Experimental investigation of the compressive behavior of epoxy nanocomposites reinforced with straight and helical carbon nanotubes

AbstractThis paper is aimed at an experimental investigation of the effect of straight and helical carbon nanotubes on the compressive behavior of epoxy nanocomposites. The epoxy nanocomposites are fabricated with varying levels of SCNT and HCNT, each with two different fabrication techniques viz. high shear mixing and ultrasonication. In samples made using high shear mixing, the compressive strength is found to actually decrease, due to poor dispersion of the CNTs, resulting in voids and clumps, which can adversely affect the strength. Ultrasonic homogenization is found to better disperse the CNTs within the epoxy resin with nearly a 10‐fold decrease in the heterogeneity size. Compression tests conducted on the ultrasonically homogenized CNT‐epoxy nanocomposites indicate a modest increase in the compressive strength. The best increase of 5% is obtained with 1% SCNT. On the other hand, the HCNT samples show a higher post‐peak residual stress suggesting an improved mode II/III fracture toughness. The high shear mixed samples exhibit a bulging deformation with no clear evidence of shear localization. On the other hand, the ultrasonic homogenization (UH) samples bulge and eventually show a clear localized shear band, likely due to a smaller heterogeneity size. Some samples with relatively poor dispersion exhibit an axial splitting failure and a comparatively low compressive strength. In addition, it is demonstrated that using acetone as a solvent during dispersion can affect the curing kinetics, which results in a nanocomposite with a rubbery consistency with low stiffness and strength, but high deformability.Highlights Straight and helical CNTs impact the compressive behavior of epoxy nanocomposites High shear mixing reduces compressive strength due to poor CNT dispersion Ultrasonication improves CNT dispersion but modest rise in compressive strength HCNTs cause higher post‐peak residual stress suggesting higher toughness Using acetone affects curing, leading to rubbery, deformable nanocomposites.

Microbial Diversity Assessment in Soil from Dumping Sites: Isolation, DNA Extraction and Electrophoretic Analysis

This study aims to investigate the microbial diversity present in soil samples collected from various dumping sites, which are known for their complex and heterogeneous waste environments. The primary objective is to isolate and characterize the microbial communities inhabiting these soils, providing insights into their composition and potential ecological roles. Soil samples were collected by digging 5 cm deep at multiple dumping locations to ensure a representative sampling of the microbial populations. The collected soil samples underwent a serial dilution process, extending up to 10^-9 and 10^-10 dilutions, to facilitate the isolation of individual microbial colonies. These diluted samples were then inoculated onto Standard Potato Dextrose Agar (PDA) media, a nutrient-rich medium conducive to microbial growth. Following an incubation period, distinct bacterial colonies were observed and isolated for further analysis. DNA was extracted from the isolated bacterial colonies using a standard DNA extraction protocol. The quality and purity of the extracted DNA were assessed through gel electrophoresis, a technique that separates DNA fragments based on their size. Remarkably, the electrophoretic analysis revealed clear and distinct DNA bands along with RNA bands, indicating successful extraction of high-quality microbial DNA. Notably, this was achieved without the use of proteinase treatment, which is typically employed to remove protein contaminants from DNA samples. The results of this study underscore the robustness of the methodologies employed in isolating and characterizing microbial DNA from soil samples collected at dumping sites. The presence of distinct DNA and RNA bands highlights the effectiveness of the DNA extraction process, even in the absence of proteinase treatment. These findings provide valuable insights into the microbial diversity within dumping site soils, suggesting a rich and varied microbial community that may play significant roles in soil health and waste decomposition.

Multiple jets in a rotating annulus model with an imposed azimuthal magnetic field

Zonal flows driven by rotation and convection are found commonly within astrophysical and geophysical bodies. Multiple jets are most famously observed on the surface of Jupiter, with prograde and retrograde zonal flows making up part of its banded structure of zones and belts. Non-magnetic studies of convection in a rotating annulus model have previously been shown to produce multiple jet structures, similar to those observed in atmospheres of giant planets such as Jupiter. These giant planets have strong magnetic fields which impact on convection in the electrically conducting regions of their atmospheres. Therefore the effect of a magnetic field on the multiple jet solutions of the annulus model is of astrophysical interest. In this work we impose a uniform azimuthal magnetic field to the annulus model and vary its strength and other control parameters to determine the parameter space where multiple jets exist. Zonal flows and multiple jet solutions are found at weak magnetic field strength and, indeed, the magnetic field can promote the production of these features. Simulations with a weak magnetic field or no magnetic field are also found to match well with the Rhines scaling theory. For cases with multiple jets, a strong inertial force must be present, combined with either a weak Lorentz force, or a Lorentz force entering the main balance with increased contributions from the viscous force. At strong magnetic field strengths two regimes are found. For weak magnetic diffusion zonal flows can be retained, albeit without the multiple jet structure. For larger magnetic diffusion non-axisymmetric solutions without clear bands are found. In these regimes, the Lorentz force appears in the primary balance of forces and zonal flows are only retained at strong driving when inertia is able to also enter the balance at leading order.

Identification and biological control of bacterial leaf spot disease of cucurbits

Objective: The present study was conducted for isolation and detection of the phyto-pathogen responsible for bacterial leaf spot disease of cucurbits as well as evaluation of its biological control techniques. Methods: The pathogen of the disease was isolated from infected leaf of bitter gourd and cultured on Luria-Bertani (LB) growth medium. The morphological tests and biochemical tests revealed the isolated bacteria as gram negative. Furthermore, advanced molecular technique was applied to facilitate proper detection of the isolated bacteria. The PCR of the bacterial genomic DNA using specific primers generated clear band of approximately 1450 bp in gel electrophoresis. Results: In gram staining test, the bacterial strain was found to be rod shaped and pinkish in color and Gram-negative. All the biochemical test showed positive without mannitol salt agar. The nucleotide sequencing of 16S rDNA gene of the bacterial isolate showed 86.02% similarities with the original sequence of Xanthomonas cucurbitae. In antibiotic sensitivity assay, the antibiotic cefixime showed highest 28.0±0.7 mm diameter of inhibition zone against the tested bacteria. The highest antibacterial activity was 8.0±0.5 mm zone of inhibition by of Allium sativum. Conclusion: The present findings may be benevolent for the detection, characterization and development of biological control techniques to prevent the leaf spot disease of cucurbits crops in Bangladesh. It may help to find out the specific signaling pathway techniques for plant microbes relationship for disease formation in future.

Rapid and reliable detection of Leishmania antibodies in canine serum with double-antigen sandwich homogeneous chemical luminescence

BackgroundLeishmaniasis, caused by Leishmania spp. parasites, is an important zoonotic disease globally, posing severe threats to humans and animals. In the absence of effective vaccines, reliable serological diagnostic methods are critical for disease control. However, the enzyme-linked immunosorbent assay (ELISA) and immunochromatographic assay have limitations due to complexity, time required and/or sensitivity. Therefore, our objective was to develop an accurate, rapid and user-friendly detection method of canine leishmania antibody based on double-antigen sandwich homogeneous chemical luminescence.MethodsHomogeneous chemiluminescent technology was employed, and expressed recombinant fusion proteins containing full-length K9, K39 and K26 repeat sequences were used as diagnostic antigens. To establish a dual-antigen sandwich serological assay capable of detecting various antibody types, a factorial design was used to optimize concentrations of diagnostic antigen-receptor microspheres and of biotinylated diagnostic antigens, as well as of reaction solution composition and reaction duration. To evaluate and validate this newly developed method, we collected 41 Leishmania-positive serum samples, 30 Leishmania-negative control serum samples and 78 clinical serum samples for which no diagnostic information was available. Comparative analyses were performed using parasitological testing and an indirect ELISA as reference methods, focusing on diagnostic sensitivity and specificity.ResultsSodium dodecyl sulfate–polyacrylamide gel electrophoresis confirmed the purification of the diagnostic antigens, which exhibited clear bands without impurities. Based on results from the 41 Leishmania-positive samples and 30 Leishmania-negative samples, there was sufficient sensitivity to detect samples diluted up to 256-fold, with analytical specificity of 100%. Overall diagnostic sensitivity was 100% and diagnostic specificity was 93.3%. Diagnostic performance was highly consistent between the newly developed method and the indirect ELISA (Kappa = 0.82, P < 0.01). Testing could be completed within 35 min with the new methodConclusionsWe have developed a novel double-antigen sandwich homogeneous chemical luminescence method to detect canine Leishmania antibodies, with high sensitively and specificity, a short incubation interval and a simple protocol. This streamlined approach not only offers a sensitive and efficient method for clinical diagnosis but also has great potential for use in automated testing.Graphical

Effect of rainfall interception and resting period on the soil seed bank

The ecosystems across the world are affected by diverse impacts of climate change. Climate change will also affect soil seed bank as the seed bank is determined by the plants that are above the ground. This study was conducted to determine whether rainfall interception and resting period will affect the soil seed bank or not. Rainfall interception was employed as main plot treatment at four different levels—namely, 15%, 30%, 60%, and 0%—and the main plot treatments were each replicated five times using the rainout shelters arranged as main plot treatments in a split-plot experimental design. The main plots are 49 m2 (7 m × 7 m) in size and were covered by metal frame structures with V-shaped clear acrylic bands on top without ultraviolet filter, and these plots were sub-divided into two sub-plots to determine the effect of resting periods (70 and 90 days). The soil samples were 8 cm in diameter and 20 cm in depth (1,005 cm3). We used seed emergence method rather than seed separation method to determine the soil seed bank due to the very small size of some seeds for some species. The 60% rainfall interception resulted in significantly high forb densities at both resting periods. The forb densities decreased by 32 and 35% at 15% and 30%, while they increased by 195% at 60% rainfall interception compared to 0% rainfall interception at 70-day resting period. Resting period significantly affected grass densities at 60% rainfall as the densities were higher at 70- than 90-day resting period. At 90-day resting period, grass densities were significantly higher at 0% rainfall interception than the rest of the treatments, while the grass densities were significantly lower at 60% rainfall interception. The 60% rainfall interception resulted in significantly (p&amp;lt; 0.05) higher total densities (forbs and grass) in both resting periods. Total density increased by 2.9% and 143.48% at 15% and 60% rainfall interception, respectively. Our results show that drought has a negative effect on grass soil seed bank, while it improves the forbs soil seed bank. Furthermore, the resting period has no significant effects on soil seed bank in grasslands.

An improved Trizol method for extracting total RNA from Eleutherococcus senticosus (Rupr. & Maxim.) Maxim leaves.

High-quality nucleic acids are the basis for molecular biology experiments. Traditional RNA extraction methods are not suitable for Eleutherococcus senticosus Maxim. To find a suitable method to improve the quality of RNA extracted, we modified the RNA extraction methods of Trizol. Based on the conventional Trizol method, the modified Trizol method 1 and modified Trizol method 2 were used as the control for extraction of RNA from E. senticosus Maxim leaves. The modified Trizol method 1 added β-mercaptoethanol on the conventional Trizol method. After RNA was dissolved, a mixed solution of phenol, chloroform, and isoamyl alcohol was added to denature protein and inhibit the degradation of RNA. The modified Trizol method 2 adds PVPP to grind on the basis of modified Trizol method 1, so as to better remove phenols from leaves, and eliminates the step of incubation at -20°C to reduce extraction time and RNA degradation. Chloroform, CTAB, and CH3COONa were used instead of a phenol, chloroform, and isoamyl alcohol mixed solution to ensure complete separation of nucleic acid from plant tissues and to obtain high-purity RNA. The research results showed that the quality of RNA extracted by conventional Trizol method, modified Trizol method 1, was incomplete, accompanied with different degrees of contamination of polysaccharides, polyphenols, and DNA. The modified Trizol method 2 could better extract RNA from E. senticosus Maxim leaves. The ratio of A260/A280 was in the range of 1.8-2.0, and the yield of RNA was the highest, which was 1.68 and 1.15 times compared with that by conventional Trizol method and modified Trizol method 1 extraction, respectively. The reverse transcription cDNA was further tested through PCR with the specific primers. The amplified fragments are displayed in clear and bright bands in accordance with the expected size. The modified Trizol method 2 could better extract RNA from E.senticosus Maxim leaves. High-quality RNA has more advantages in molecular biology study of E.senticosus Maxim.

HPTLC FINGERPRINTS AND FTIR ANALYSIS FOR AUTHENTICATION AND QUALITY CONTROL OF Holostemma ada-kodien Schult.

Plant-derived pharmaceuticals are gaining increased acceptance in treating various ailments, but ensuring their quality is crucial. Both conventional and modern techniques are employed to validate the quality. High performance thin layer chromatography (HPTLC) and Fourier transform infra-red (FTIR) analysis were conducted to analyse and identify the various phytoconstituents in serial root extract of Holostemma ada-kodien. The peaks observed in HPTLC fingerprint profile corresponding to different phytoconstituents served as markers for standardizing drug; while FTIR analysis aids in identifying the major functional groups present. Thirteen bands were noted for hexane extract of H. ada-kodien in short UV in track I, while chloroform and methanol extracts showed eight bands each. In track II, the hexane extract exhibited eight bands, while chloroform and methanol extracts showed eleven and eight bands, respectively, under similar conditions. The hexane extract in long UV showed a maximum area of 78.4 and 71.59%, in track 1 and 2, respectively, with respective spanning from Rf 0.61 to 0.75 and 0.51 to 0.73. The methanol extract in visible light in track I showed a maximum area of 46.87%, spanning from Rf 0.73 to 0.98, and in track II, it displayed a maximum area of 36.59%, spanning from Rf 0.75 to 0.96 with 10 µL applied. Methanolic root extract of H. ada-kodien showed clear banding patterns in HPTLC fingerprints which seemed to be a dependable technique to detect adulteration while FTIR technique revealed functional groups of methanol root extracts.

Methyl-Sensitive Amplification Polymorphism (MSAP) Analysis Provides Insights into the DNA Methylation Changes Underlying Adaptation to Low Temperature of Brassica rapa L.

DNA methylation can change rapidly to regulate the expression of stress-responsive genes. Previous studies have shown that there are significant differences in the cold resistance of winter rapeseed (Brassica rapa L.) after being domesticated in different selection environments; however, little is known about the epigenetic regulatory mechanisms of its cold resistance formation. Four winter rapeseed materials ('CT-2360', 'MXW-1', '2018-FJT', and 'DT-7') domesticated in different environments were selected to analyze the DNA methylation level and pattern changes under low temperature using methylation-sensitive amplified polymorphism technology with 60 primer pairs. A total of 18 pairs of primers with good polymorphism were screened, and 1426 clear bands were amplified, with 594 methylation sites, accounting for 41.65% of the total amplified bands. The total methylation ratios of the four materials were reduced after low-temperature treatment, in which the DNA methylation level of 'CT-2360' was higher than that of the other three materials; the analysis of methylation patterns revealed that the degree of demethylation was higher than that of methylation in 'MXW-1', '2018-FJT', and 'DT-7', which were 22.99%, 19.77%, and 24.35%, respectively, and that the methylation events in 'CT-2360' were predominantly dominant at 22.95%. Fifty-three polymorphic methylated DNA fragments were randomly selected and further analyzed, and twenty-nine of the cloned fragments were homologous to genes with known functions. The candidate genes VQ22 and LOC103871127 verified the existence of different expressive patterns before and after low-temperature treatment. Our work implies the critical role of DNA methylation in the formation of cold resistance in winter rapeseed. These results provide a comprehensive insight into the adaptation epigenetic regulatory mechanism of Brassica rapa L. to low temperature, and the identified differentially methylated genes can also be used as important genetic resources for the multilateral breeding of winter-resistant varieties.

A Comparative Study of "Grafting to" and "Grafting from" Conjugation Methods for the Preparation of Antibody-Temperature-Responsive Polymer Conjugates.

Early diagnosis of infectious diseases is still challenging particularly in a nonlaboratory environment or limited resources areas. Thus, sensitive, inexpensive, and easily handled diagnostic approaches are required. The lateral flow immunoassay (LFIA) is commonly used in the screening of infectious diseases despite its poor sensitivity, especially with low pathogenic loads (early stages of infection). This article introduces a novel polymeric material that might help in the enrichment and concentration of pathogens to overcome the LFIA misdiagnosis. To achieve this, we evaluated the efficiency of introducing poly(N-isopropylacrylamide) (PNIPAAm) into immunoglobulin G (IgG) as a model antibody using two different conjugation methods: grafting to (GT) and grafting from (GF). The IgG-PNIPAAm conjugates were characterized using SDS-PAGE, DLS, and temperature-responsive phase transition behavior. SDS-PAGE analysis revealed that the GF method was more efficient in introducing the polymer than the GT method, with calculated polymer introduction ratios of 61% and 34%, respectively. The GF method proved to be less susceptible to steric hindrance and more efficient in introducing high-molecular-weight polymers into proteins. These results are consistent with previous studies comparing the GT and GF methods in similar systems. This study represents an important step toward understanding how the choice of polymer incorporation method affects the properties of IgG-PNIPAAm conjugates. The synthesized polymer allowed binding and enrichment of mouse IgG that was used as a model antigen with a clear LFIA band. On the basis of our findings, this system might help in improving the sensitivity of simple diagnostics.

Development and characterization of novel EST-SSR markers for Gentiana straminea Maxim., a traditional Tibetan herb in China and cross-amplification in related species

Abstract Gentiana straminea Maxim. (Gentianaceae) is an important traditional Tibetan herb that is mainly distributed on the Qinghai-Tibetan Plateau. Despite its agricultural and pharmacological importance, there remains a paucity of microsatellite markers, particularly expressed sequence tag-simple sequence repeat (EST-SSR) markers, available for this local endemic species. In this study, based on previous Illumina transcriptome data of G. straminea, a total of 96 EST-SSR markers were initially designed and tested. Thirty-two of 96 loci (33.33%) were successfully amplified and verified for validation. Among them, 10 were polymorphic and had clear bands. The polymorphism information content values were 0.09–0.799, the number of alleles per locus ranged from 3 to 14, and the levels of observed and expected heterozygosity were 0.078–0.722 and 0.238–0.884, respectively, which suggested a high level of information. Moreover, cross-amplification was successful for 10 loci in two other related species, Gentiana macrophylla Pallas and Gentiana dahurica Fischer. These EST-SSR markers provide a valuable tool for investigating the genetic diversity related to quantitative traits and population genetic studies on G. straminea and related species in sect. Cruciata Gaudin.

Multicolour photometry of LEO mega-constellations Starlink and OneWeb

ABSTRACT The development of low earth orbit (LEO) mega-constellation fundamentally threatens ground-based optical astronomical observations. To study the photometric properties of the LEO mega-constellations, we used the Xinglong 50 cm telescope to conduct a large-sample, high-precision, and multicolour target-tracking photometry of two typical LEO mega-constellations: Starlink and OneWeb. Over a three-month observation period starting on 2022 January 1, we collected 1447 light curves of 404 satellites in four typical versions: Starlink v1.0, DarkSat, VisorSat, Starlink v1.5, and OneWeb. According to data statistics, Starlink v1.0 has the smallest median magnitude at clear and Sloan Digital Sky Survey gri band, and OneWeb is the dimmest bus. The brightness of Starlink v1.5 is slightly brighter than VisorSat. We construct a detailed photometric model with solar phase angle variations by calculating the illumination-visibility geometry based on the orbital parameters. Our data analysis shows that the solar phase angle is the significant characteristic which influencing Starlink satellites’ brightness, but it is not sensitive to OneWeb satellites. VisorSat and Starlink v1.5 versions, which are equipped with deployable visors, have significantly reduced scattered light compared to the previous Starlink v1.0 version. The multiband LOWESS and colour index are analysed in characterizing the energy and colour features of LEO mega-constellation satellites. This work found that the proportion of scattered sunlight mitigation achieved with VisorSat and Starlink v1.5 was 55.1 and 40.4 per cent, respectively. The colour index of different buses shows an evident clustering feature. Our observation and analysis could provide valuable quantitative data and photometric models, which can contribute to assessing the impact of LEO mega-constellations on astronomical observations.

A preliminary investigation on the mechanical behaviour of a stiff Italian clay in the context of hydrogen storage

The large-scale use of renewable energy sources is closely linked to the ability to store excess energy generated during periods of overproduction for use when demand is at a peak. Storing green energy is therefore a key component in the move towards a carbon-neutral economy. Underground hydrogen storage in depleted oil and gas reservoirs may provide an efficient long-term solution. Cyclic injection and production of hydrogen alter the chemo-hydro-mechanical conditions of the reservoir and caprocks, and possible geomechanical consequences of such alterations must be preliminarily assessed for safe storage operations. This study aims at exploring the possible effects of cyclic mechanical loads, such as those that might be induced by hydrogen storage and production, on the mechanical behaviour of a clayey caprock. A series of triaxial tests, both monotonic and cyclic, were carried out on undisturbed samples of a stiff Italian clay cored from a caprock formation overlying a hydrocarbon reservoir. The results show that the material response is characterized by the distinctive stress-strain behaviour of stiff clays, with a rather high fragility, which was found to be highly dependent on the loading strain rate. During laboratory experiments conducted at frequencies larger than in situ ones, cyclic loading under stress control causes a gradual degradation of the material structure leading to the formation of a clear shear band followed by a reduction in shear strength. Eventually, failure occurs as the peak shear strength approaches the applied load. The progressive destructuration also implies a reduction in P- and S-wave propagation velocities and a significant change in the signal shape, which is therefore a promising parameter for monitoring the material degradation process.

A Novel Method for Cloud and Cloud Shadow Detection Based on the Maximum and Minimum Values of Sentinel-2 Time Series Images

Automatic and accurate detection of clouds and cloud shadows is a critical aspect of optical remote sensing image preprocessing. This paper provides a time series maximum and minimum mask method (TSMM) for cloud and cloud shadow detection. Firstly, the Cloud Score+S2_HARMONIZED (CS+S2) is employed as a preliminary mask for clouds and cloud shadows. Secondly, we calculate the ratio of the maximum and sub-maximum values of the blue band in the time series, as well as the ratio of the minimum and sub-minimum values of the near-infrared band in the time series, to eliminate noise from the time series data. Finally, the maximum value of the clear blue band and the minimum value of the near-infrared band after noise removal are employed for cloud and cloud shadow detection, respectively. A national and a global dataset were used to validate the TSMM, and it was quantitatively compared against five other advanced methods or products. When clouds and cloud shadows are detected simultaneously, in the S2ccs dataset, the overall accuracy (OA) reaches 0.93 and the F1 score reaches 0.85. Compared with the most advanced CS+S2, there are increases of 3% and 9%, respectively. In the CloudSEN12 dataset, compared with CS+S2, the producer’s accuracy (PA) and F1 score show increases of 10% and 4%, respectively. Additionally, when applied to Landsat-8 images, TSMM outperforms Fmask, demonstrating its strong generalization capability.

Fractionating microplastics by density gradient centrifugation: a novel approach using LuerLock syringes in a low-cost density gradient maker

Abstract Microplastics are now ubiquitous in the environment and are even considered “technofossils” of the Anthropocene. Given their omnipresence and potential impact, identifying and analyzing these particles becomes increasingly crucial. Novel approaches suggest density gradient centrifugation for simultaneous extraction and fractionation of microplastic particles based on their plastic-specific densities. In this article we describe a cheap and harmless experimental setting to fractionate microplastic particles by density gradient centrifugation. An innovative low-cost Do-It-Yourself (DIY) gradient maker using Luer-Lock syringes is presented. With this gradient maker it is possible to produce density gradients with water and sucrose solutions, covering a density range of 1.00–1.32 g/cm3, as well as with water and saturated potassium carbonate solutions, covering a density range of 1.06–1.53 g/cm3. The separation performance was tested with the most broadly used plastics polyamide, polyurethane, polycarbonate, polyethylene terephthalate and polyvinylchloride. Both density gradients show centrifugation stability and clear banding patterns after centrifugation. Due to its cheap and easy-to-build-easy-to-use nature, this experimental setting for microplastic fractionation by density gradient centrifugation offers an approach for schools not only to address the microplastic problems, but also to integrate new methods of microplastic analysis in upper secondary school laboratories.

Ammonium-rich bright areas on Ceres demonstrate complex chemical activity

The dwarf planet Ceres has been proven to be a world with an extraordinary diversity of chemical species formed in aqueous environments. Dantu crater, being one of the largest and deepest impact craters on Ceres, offers valuable insights into the geological history and composition of this enigmatic world. Its particular position, within a topographic low, can be considered a window into the composition of Ceres’s subsurface. One of the intriguing aspects of Dantu is the presence of several bright areas called “faculae”. These bright materials, distributed unevenly on the Cerean surface, are believed to be residua from salty fluids, likely still circulating in the subsurface and capable to extrude onto the surface, as demonstrated by the identification of fresh hydrohalite (NaCl·2(H2O)) on the bright faculae in another exceptional crate, Occator. The detailed investigation of the Dantu’s faculae reveals the presence of at least two different “populations” of bright materials, compositionally distinct even if in close geographical proximity. These faculae appear different, white and yellow, in the color images (RGB: R = 0.917 μm, G = 0.653 μm, B = 0.438 μm) taken by the Dawn camera. The spectra show that the first population -white- is mainly composed of sodium carbonate, similar to other identified bright areas on Ceres; the second one -yellow- is likely dominated by ammonium-rich components. The spectra of the yellow faculae show specific and clear bands, associated to ammonium bearing phases, but the exact species producing such spectral features are not unambiguously identified. A potential candidate is ammonium bicarbonates, but we cannot exclude other compounds and combinations of different species. Other occurrences of these yellow faculae have been identified in a few other areas, even if less numerous and with a much smaller extent with respect to the Dantu crater. The discovery of a very bright component different from the carbonates and salts previously identified increases the variety and complexity of the salty aqueous solutions on Ceres, offering tantalizing clues about the potential for habitable environments and subsurface fluid reservoirs on this dwarf planet.