Predominant Peak Research Articles

Injector Port Acylation of γ-hydroxybutyrate (GHB): condition optimisation, source adjustments, and characterisation of the derivatives.

For several years, gas chromatography-mass spectrometry (GC-MS) has been used to identify gamma-hydroxybutyrate (GHB) in forensic toxicology cases. However, under injector port conditions GHB can dehydrate into gamma-butyrolactone (GBL). Therefore, it is important for GHB to undergo a derivatisation reaction before an analysis to avoid the production of GBL; various analytical methods have been developed for the analysis of GHB but very few methods use acylation as a form of derivatisation. This study explores the optimisation of injector port acylation of GHB to improve its detectability and thermostability. By utilising trifluoroacetic acid anhydride (TFAA) and heptafluorobutyric acid anhydride (HFBA) to enhance the chromatography and mass spectra of the resulting derivatives. As a result, both reagents improved the detectability of GHB, with TFAA producing more predominant peaks within the chromatogram and HFBA offering a more complex mass spectrum. The optimal injector temperature was found to be 240°C for both reagents, which significantly increased the derivatisation yields. These results demonstrate the effectiveness of injector port acylation as an alternative derivatisation route for GHB related drug cases.

Identification of the drug/metabolite transporter 1 as a marker of quinine resistance in a NF54×Cam3.II P. falciparum genetic cross.

The genetic basis of Plasmodium falciparum resistance to quinine (QN), a drug used to treat severe malaria, has long been enigmatic. To gain further insight, we used FRG-NOD human liver-chimeric mice to conduct a P. falciparum genetic cross between QN-sensitive and QN-resistant parasites, which also differ in their susceptibility to chloroquine (CQ). By applying different selective conditions to progeny pools prior to cloning, we recovered 120 unique recombinant progeny. These progeny were subjected to drug profiling and QTL analyses with QN, CQ, and monodesethyl-CQ (md-CQ, the active metabolite of CQ), which revealed predominant peaks on chromosomes 7 and 12, consistent with a multifactorial mechanism of resistance. A shared chromosome 12 region mapped to resistance to all three antimalarials and was preferentially co-inherited with pfcrt. We identified an ATP-dependent zinc metalloprotease (FtsH1) as one of the top candidates and observed using CRISPR/Cas9 SNP-edited lines that ftsh1 is a potential mediator of QN resistance and a modulator of md-CQ resistance. As expected, CQ and md-CQ resistance mapped to a chromosome 7 region harboring pfcrt. However, for QN, high-grade resistance mapped to a chromosome 7 peak centered 295kb downstream of pfcrt. We identified the drug/metabolite transporter 1 (DMT1) as the top candidate due to its structural similarity to PfCRT and proximity to the peak. Deleting DMT1 in QN-resistant Cam3.II parasites significantly sensitized the parasite to QN but not to the other drugs tested, suggesting that DMT1 mediates QN response specifically. We localized DMT1 to structures associated with vesicular trafficking, as well as the parasitophorous vacuolar membrane, lipid bodies, and the digestive vacuole. We also observed that mutant DMT1 transports more QN than the wild-type isoform in vitro. Our study demonstrates that DMT1 is a novel marker of QN resistance and a new chromosome 12 locus associates with CQ and QN response, with ftsh1 is a potential candidate, suggesting these genes should be genotyped in surveillance and clinical settings.

Comparative Study on PSD and HHT Techniques for Condition Assessment of Steel Truss Bridge Using Acceleration Data

Bridge structures deteriorate over time due to factors like corrosion, fatigue, aging of materials, and unexpected natural or accidental events. Consequently, the vibrations measured in these structures exhibit time-varying and non-stationary characteristics. Additionally, non-linearities are inherent in these structures due to material behavior, boundary condition changes, and joints or connections. Analysis of non-linear and non-stationary structural vibration data is necessary to extract information on the condition of the bridge. Most methods assessing bridge conditions from acceleration responses rely on the Power Spectral Density (PSD) which is based on the Fourier Transform. However, the accuracy of the Fourier transforms for non-linear and non-stationary signals limits its application potential. The Hilbert–Huang Transform (HHT) has emerged as an alternative for handling these non-stationary signals due to its time-frequency-energy representation. This study provides a comparative study of both techniques by utilizing the data obtained from continuously monitored Pamban Bridge. This steel truss bridge was fitted with accelerometers to record bidirectional acceleration time histories at twenty bottom node points on the bridge. This study examines the continuous variations in the frequency component by both methods for 136 days. A linear best-fit trendline is obtained for the frequency parameters at different sensor positions. The slope and intercept values of this linear best fit trendline is further studied. The HHT showcases various evolving dominant frequency components over time in contrast to the PSD representation. The frequency spectrum from the HHT displays less variation over time at each sensor position compared to the predominant peak value derived from the PSD of the acceleration signal. The spatial variability in the predominant frequency obtained from HHT is also less than the PSD. Therefore, the ability of HHT to discriminate damages needs further investigations.

Selenium‐chitosan engineered nanocomposite as efficient formulated fish diet evaluated for sustainable aquaculture practice of Oreochromis niloticus (Nile tilapia) fishes

AbstractOreochromis niloticus a Nile tilapia fish is widely used for fish culture practice in many countries for its easy acclimatization and high yield at a short pace of time. Selenium‐chitosan (SeCh) nanoparticles are efficiently used in agriculture, medicine, and aquaculture practices in several studies. The significant approach of Selenium‐Chitosan incorporated fish feed will be evaluated in the present study to achieve the better aquaculture practice in future. In the present study, SeCh nanoparticle was chemically synthesized and incorporated with formulated fish feed. Selenium formulated fish feed contains 31.49 g of carbohydrates and 41.52 g of proteins. SeCh‐fed O. niloticus fingerlings exhibited significantly increased specific growth rates in terms of weight gain, and feed conversion ratio. Chemical characterization of SeChNPs through FTIR spectroscopy indicates the presence of an adjuvant combination of selenium and chitosan presence through functional groups of COO stretch, CH, CC, and CN stretch representing at 3226, 2878, and 1734 cm−1, respectively. Scanning electron microscopy (SEM) and EDX analysis revealed the structural properties of SeChNPs as a fibrous pattern that contains Carbon, Oxygen, and Selenium elements as predominant peak values. SeChNPs incorporated fish feed has higher protein content which is a standard hallmark for a fish feed and an essential prerequisite for fish growth. The formulated SeCh fish feed in the present study is an innovative approach which can be taken further for higher level testing and processing for developing as a better fish feed in terms of feasible and efficient fish growth enhancer.

An alkaloidal fraction of Annona tomentosa possesses anthelmintic activity and induces surface modifications in Haemonchus contortus

The nematode Haemonchus contortus is, as a parasite, responsible for most mortality of small ruminants, causing significant economic losses. Numerous plant-derived compounds have exhibited promising anthelmintic activities against this nematode. Notably, the Annona genus stands out for demonstrated anthelmintic effects by extracts from several of its species against different nematodes. This study aimed to assess the effect of an Annona tomentosa fraction, rich in alkaloids, on H. contortus. This fraction, named Alk.F, is derived from the methanolic extract of the plant’s stem bark. Chemical characterization of Alk.F was performed by liquid chromatography coupled with mass spectrometry. Among the nine predominant peaks obtained, seven alkaloids were identified: reticuline, reticuline N-oxide, reticuline N-oxide isomer, cyclanoline, asimilobine, tetrahydropalmatine and anonaine. Alk.F inhibited the larval development of H. contortus with an IC50 of 0.026 mg/mL, inhibited larval exsheathment with an IC50 of 0.38 mg/mL, and displayed low hemolytic activity towards sheep erythrocytes. Furthermore, atomic force microscopy revealed that Alk.F altered adhesive forces and the height profile on the surface of H. contortus larvae. In conclusion, A. tomentosa alkaloids alter the cuticle structure of H. contortus, inhibiting larval development and exsheathment, thus offering possibilities for contributing to the development of new anthelmintic drugs.

Development and understanding of the lithiation/de-lithiation mechanism of a low cobalt and nickel-rich cathode material for lithium‐ion batteries

Nickel-rich LiNixMnyCo1−x−yO2 (NMC, with x ≥ 0.6) layered oxides are regarded as cathode candidates for high-energy density lithium-ion batteries (LIBs). However, this technology faces several challenges due to the scarcity of crucial raw materials such as cobalt precursors and the negative environmental impact of their extraction process. It is therefore, it becomes imperative to develop low cobalt content cathode compositions that offer alternative options with comparable electrochemical performance. Herein, we have used a systematic approach to modify the composition while keeping all other properties (particle size and morphology) constant to synthesise low-Co-cathode materials, namely LiNi0·8Mn0·1Co0·1O2 (NMC-10 %) and LiNi0·8Mn0·15Co0·05O2 (NMC-5%). A co-precipitation route using a continuous stirred thank reactor was used for synthesis. The physico-chemical properties, electrochemical performances, cycling stability, and rate capabilities of NMC-5% materials are comparable to those of NCM-10 % materials. NMC-10 % and NMC-5% half cells show initial specific discharge capacities of 191 mAh.g−1, and 185 mAh.g−1, respectively, in a voltage range of 2.8–4.3 V (vs. Li+/Li). The NMC-5% exhibits excellent thermal stability, characterized by a predominant exothermic peak at 432 °C and significantly lower total heat energy when compared to NMC-10 % counterpart, which displayed its main exothermic peak at 339 °C. The structural and electronic changes of both materials were evaluated through in operando synchrotron-based X-ray techniques. Regardless of the cobalt content, both materials show comparable structural and electronic evolution upon the de-intercalation/intercalation of Li+ ions. An irreversible phase transition at the first delithiation was observed as emphasized by diffraction of synchrotron radiations.

Coexistence of passive vortex-induced vibrations and active pitch oscillation triggered by a square cylinder attached with a deformable splitter plate

To understand passive vortex-induced vibrations (VIV) coexisting with active structure motions, this paper numerically investigates the use of pure pitch oscillation to control a square cylinder mounted with a deformable splitter plate at the Reynolds number of 333. The oscillation is enforced with an amplitude of 3° and different frequencies from 0 to 6 Hz. Direct numerical simulations using a partitioned method with a semi-implicit coupling algorithm are performed. According to the trajectories of the splitter-plate tip displacement with respect to the lift or drag force coefficient, a specific lock-in regime determined by the frequency of the enforced pitch oscillation is identified. Further spectral analyses of the tip displacement and lift force show that the lock-in frequencies are equal to the enforced frequencies. Next to the lock-in regime, semi-lock-in regimes with narrow bandwidths are distinguished, exhibiting both lock-in and non-lock-in features. In the non-lock-in regimes, the frequencies of the most predominant peaks in the spectra are found near the natural frequency of the splitter plate of 3.236 Hz, and the frequencies of the two secondary peaks are distributed along the characteristic lines following the ratios of these frequencies to the enforced frequency, which are ±1. Thus, the interaction is dependent on the combined effects of the passive VIV and the actively enforced pitch oscillations. Moreover, the intersection points of the characteristic lines are located close to the upper and lower frequency limits of the lock-in regime, inferring the conditions for the lock-in onset.

Nitrogen doped single layer graphene for CZTS-based thin film solar cells

CdS thin films are commonly utilized as a buffer layer in chalcopyrite thin-film solar cells. However, due to the toxic nature of Cadmium (Cd), ongoing efforts are being directed towards exploring alternative options. In this contribution, doped graphene film with remarkable optical and electrical properties has been introduced for the first time as an alternative buffer layer, replacing CdS in CZTS thin-film solar cell application. In this study, nitrogen-doped graphene (N-doped graphene) film was utilized as a substitute buffer layer in the CZTS thin-film solar cell structure, replacing the conventional CdS thin film. For comparative analysis, CZTS/N-doped graphene and CZTS/CdS traditional solar cell structures were fabricated and separately characterized. The CZTS thin films produced were examined through EDX, XRD, SEM, Raman, optical transmission and PL spectroscopy measurements. According to performed analyses, the Cu-poor and Zn-rich kesterite CZTS thin films exhibited a uniform and dense polycrystalline microstructure as observed in surface and cross-sectional SEM images. XRD spectra of the kesterite CZTS thin film displayed predominant peaks corresponding to the (112), (220/204), and (312/116) diffraction planes of the kesterite CZTS phase. Raman spectra showed a dominant peak at ∼336 cm−1 associated with the kesterite CZTS phase. PL emission spectra indicated transitions from the conduction band to defect levels. The CVD-grown doped graphene film exhibited a 3.43 I2D/IG ratio and a 25 cm−1 FWHM of the 2D peak, indicating a single-layer graphene according to Raman analysis. Permanent nitrogen doping with a 2% atomic concentration was confirmed by XPS measurement. The optical transmission measurement of the single layer doped graphene film showed a 95% transmittance value. Nitrogen doping was contributed to decrease the sheet resistance of the graphene film. The Glass/Mo/CZTS/N-doped graphene/i-ZnO/ITO/Al solar cell displayed a VOC of 0.267 V, JSC of 24.6 mA/cm2, FF of 36.46, and η of 2.37%, showing higher FF and Jsc values but lower conversion efficiency compared to the Glass/Mo/CZTS/CdS/i-ZnO/ITO/Al traditional solar cell structure. Hence, the superior working function and transparency properties position the N-doped graphene film as a competitive buffer layer for use in CZTS-based thin-film solar cells.

Effects of W6+ on the microstructure, sinterability, lattice vibration, and dielectric properties of Pr2Zr3(Mo1˗xWxO4)9 ceramics at microwave/terahertz/infrared regions

In this article, a series of Pr2Zr3(Mo1−xWxO4)9 ceramics were prepared using the solid-state reaction method and investigated in terms of phase compositions, lattice stress, lattice vibrations, and dielectric properties at microwave, terahertz, and infrared regions. X-ray diffraction (XRD) analysis revealed that all ceramics possess a trigonal structure (R-3c space group) with no discernible second-phase presence. Moreover, the ceramics exhibit oriented growth along the (0,0,18) crystal plane. The densification of all ceramics occurred within the range of 800–825 °C. Raman spectroscopy exhibited a minor blue shift in the predominant peak as the x value increased. The complex permittivity (ε′ and ε″) were evaluated using both infrared reflectance spectrum and terahertz time-domain (THz-TD) spectroscopy. Interestingly, the THz-TD spectral data exhibited a closer agreement with the measured values, which was attributed to a significant relaxation polarization mechanism. Specifically, the peaks below 400 cm−1 contributed significantly to the dielectric parameters, accounting for 88.4% and 95.7% of ε′ and ε″, respectively. As a result of these findings, it is suggested that Pr2Zr3(Mo0.94W0.06O4)9 (εr = 9.82, Qf = 81,892 GHz, τf = −17.90 ppm/°C) ceramics synthesized at 825 °C hold promise as potential materials for high-frequency communication circuits.

A novel digitonin/graphene oxide/iron oxide nanocomposite: synthesis, physiochemical characterization and antioxidant activity.

In this work, iron oxide (Fe3O4) magnetic nanoparticles (MNPs) and graphene oxide (GO) nanosheets were prepared via the co-precipitation technique and the Modified Hummer method. Fe3O4 MNPs and GO nanosheets were combined to prepare Fe3O4/GO nanocomposite and subsequently conjugated with Digitonin (DIG) in order to obtain a dual-targeted delivery system based on DIG/Fe3O4/GO nanocomposite. SEM images reveal the presence of Fe3O4 MNPs at a scale of 100nm, exhibiting dispersion between the GO nanosheets. Aggregation of the DIG/Fe3O4/GO nanocomposite was observed at various size scales. The XRD structural analysis confirms the crystal structure of the prepared samples. The Fe3O4 MNPs demonstrated the main XRD-diffracted peaks. Also, GO nanosheets exhibit crystalline characteristics on the (001) and (002) planes. The predominant peaks observed in the DIG/GO/Fe3O4 nanocomposite are attributed to the crystal phases of Fe3O4 MNPs. The FT-IR vibrational modes observed in the GO/DIG/Fe3O4 nanocomposite indicate the presence of crosslinking between GO nanosheet layers and the Fe3O4 MNPs. The antioxidant activity of the prepared samples was measured and the DIG/GO/Fe3O4 nanocomposite demonstrated a significantly high antioxidant activity in both 2-diphenyl-1-picrylhydrazyl (DPPH·) and 2,2-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS·+) tests.

Sedimentary stratigraphy and provenance off Dronning Maud Land (East Antarctica) during the mid-Pleistocene transition: Implications for paleoclimate and ice dynamics

Glacial-marine sediments from the Antarctic continental margin provide a record of depositional environment, oceanographic variability and ice dynamics that is tapped with scientific ocean drilling. This study focuses on Ocean Drilling Program Core 693A-2R, a 9.7 m sediment core retrieved from near the continental margin of the Archean Grunehogna Craton in Dronning Maud Land (DML), East Antarctica. The results contribute to a better understanding of ice-shelf behavior in DML during the mid-Pleistocene transition (MPT), a well-known transition from 40-kyr to 100-kyr cycle periods. The age model, constructed based on Sr isotope stratigraphy and geomagnetic reversals, indicates that the core spans 1.20 to 0.65 Ma. The dynamic behavior of DML ice shelves with periodic iceberg calving is revealed by the glacial–interglacial variation in sedimentation patterns, with interglacials characterized by higher concentrations of ice-rafted debris (IRD) associated with enhanced paleoproductivity than glacial intervals. The responses of DML ice shelves to warm climates are represented by a prolonged interglacial period at 1.0–1.1 Ma (MIS 31–27) and significant interglacial expressions during MIS 19 and 17. The 40Ar/39Ar ages of individual ice-rafted hornblende grains are compared with the on-land geology of DML and neighboring regions to determine the provenances of IRD. Specifically, 40Ar/39Ar results record primarily late Neoproterozoic to Cambrian ages (600–400 Ma) with a predominant peak of 520–480 Ma. This Pan-African/Ross orogeny signature is very common in East Antarctica but is not found in the most proximal margin of the Grunehogna Craton, and is instead associated with the region of DML several hundred kilometers east of the deposition site. This indicates that significant discharges of icebergs occurred in the remote DML, which were then transported by the westward-flowing Antarctic Coastal Current to deposit IRD at the studied site during the MPT. This study establishes a confirmed MPT sedimentary sequence off DML, against which future MPT proxy records from the Weddell Sea embayment and other sectors in Antarctica can be compared and correlated, and provides a basis for more detailed analyses of the response of DML ice sheet to Pleistocene climate variations.

Optimisation of Polyhydroxy Butyrate Production by Lysinibacillus fusiformis and Metabacillus indicus isolated from Spent Engine-oil Contaminated Soil

This study isolated bacteria from spent engine oil-contaminated soil and optimized their production of polyhydroxybutyrate (PHB), a biodegradable polymer belonging to the polyesters classes that are of interest as bioderived and biodegradable plastics. Out of 12 bacterial isolates (species of Bacillus, Pseudomonas, Staphylococcus and Lactobacillus) recovered from the spent engine oil contaminated soils, and screened for their capacity to accumulate polyhydroxybutyrate (PHB), only two bacterial isolates (Lysinibacillus fusiformis and Metabacillus indicus), showed significant PHB production. L. fusiformis produced PHB at a concentration of 1.5 g/L, while M. indicus produced PHB at a concentration of 1.0 g/L. Optimal production conditions included a temperature of 35°C, agitation speed of 100 rpm, neutral pH of 7.0, glucose as the carbon source, and peptone as the nitrogen source. Gas chromatography-mass spectrometry confirmed the presence of PHB in the extracted samples, with hexadecanoic acid methyl ester identified as the predominant peak. These findings highlight the potential of bacteria from engine oil-contaminated soil as efficient PHB producers and contribute to the development of sustainable and biodegradable plastics.

Temperature/electric field induced photoluminescence-modulation effect in dysprosium-doped barium titanate ferroelectric ceramics

Lanthanide (Ln3+) based ferroelectric phosphors, with an integration of PL emission and ferroelectric effect, are unveiling an exciting realm of possibilities for multifunctional ferroelectric-optic materials. However, how the ferroelectric host enables the tuning on the PL emissions through modulating the local structure (e.g., lattice site, symmetry, strains etc.) of the Ln3+ activator is not established yet. In this work, a luminescent-ferroelectric material, i.e. Dy3+ doped BaTiO3 ceramic (Ba1–xDyxTiO3 (x = 0–0.07), abbr: BTO:Dy3+), was explored to address the aforementioned issues. The BTO:Dy3+ ceramics were synthesized by a solid-state reaction method. The crystal structure, photoluminescence (PL) and electric properties (dielectric constant, ferroelectric hysteresis and piezoelectric hysteresis loop) were systematically investigated. The BTO:Dy3+ ceramics show two predominant emission peaks, corresponding to the blue magnetic dipole transition (477 nm, 4F7/2 → 6H15/2) and yellow electric dipole transition (573 nm, 4F7/2 → 6H13/2), the intensity ration of which can be modulated by the ferroelectric polarization that causes the slight lattice deformation. Such a polarization-emission modulation combining with the Dy3+ doping could accelerate the color change, from yellow to blue, which is characterized to detect the phase transition, with a method and mechanism were proposed, that is, the phase change is reflected by the PL characteristic peak intensity ratio. Therefore, the current results offer a convenient photoluminescence method for detecting the ferroelectric phase transition and a feasible approach to study the interaction between the photoluminescence and polarization in ferroelectric materials, for providing new insights for the development of multifunctional materials.

Contribution of HVSR, MASW, and geotechnical investigations in seismic microzonation for safe urban extension: A case study in Ghabt Admin (Agadir), western Morocco

Ghabt Admin, located in western Morocco, is prone to seismic activity and site effects due to its position within an alluvial basin situated between two faulted mountain belts. The region has experienced several devastating earthquakes, including the 1960 Agadir earthquake that resulted in the loss of 12,000 lives and the destruction of over 75% of the city. Moreover, the area has recently undergone rapid urbanization, necessitating the implementation of seismic studies to make informed decisions regarding land use. This study aims to conduct the first seismic microzonation and site characterization studies by using HVSR, 1D-MASW, and geotechnical investigations. The datasets consist of 80 microtremors, 15 1D-MASW profiles, detailed geological observations, boreholes, and soil/rock identification tests. Due to challenges related to anthropogenic sources and soil heterogeneities, only 31 H/V measurements met the SESAME criteria. The HVSR results indicate the following: (i) the predominant peak frequency (f0) ranges from 1.4 to 15.7 Hz, with lower values (1.4–3 Hz) observed in the Oued Issen alluvial fans and the sand dune area, while moderate to high values (4–15.7 Hz) are found in the lacustrine limestone and Tagragra’s dome. (ii) The amplitude peak frequency (A0) ranges from 2 to 7.7, with higher values observed in the southwestern zone and certain parts of the glacis-fans zone, particularly in the Oued Issen zone. (iii) The seismic vulnerability index (Kg) ranges from 0.28 to 39.5. The Oued Issen area, which is composed of recent unconsolidated deposits and affected by the Oued Issen fault, exhibits high Kg values. Analysis of HVSR curve typology reveals complex geology. The VS30 map shows VS values ranging from 179 m/s to 830 m/s, classifying the study area into soil classes A, B, and C according to Eurocode 8. Furthermore, the 1D-MASW results are compatible with the HVSR results and the distribution of the geological units.

Growth of high carrier mobility 2-Dimensional hexagonal Bi2Te3-xSex nanoplatelets and its thermoelectric performance studies

Morphologically controlled growth of selenium-doped 2-Dimensional (2D) Bi2Te3-xSex nanoplatelets have been optimized by solvothermal synthesis using polyvinyl-pyrro-lidone (PVP) surfactant from the pre-optimized growth conditions of 2D-Bi2Te3 hexagonal nanoplatelet. An optimization was carried out using the Se-doping of x = 0.3 under variable growth durations of 4 h, 8 h, and 12 h. X-ray powder diffraction studies confirmed the complete crystallization with a pure phase of 2D-Bi2Te3-xSex at an extended duration of 12 h synthesis. Crystallization with defined hexagonal morphology was confirmed by FESEM analysis. Selenium doping into the 2D-Bi2Te3-xSex lattice from x = 0.1 to x = 0.4 indicates a step-by-step shift in the 2θ value of the (015) predominant peak towards higher 2θ values. Raman analysis revealed the alteration of the appearance of A1u2 to A1g2 upon the lattice inclusion of “Se” in the place of “Te”. Hall measurements on the consolidated pellet of 2D-Bi2Te3-xSex resulted in the highest electron mobility of 1675 cm2V−1s−1 with carrier concentration of 2.9 × 1018 cm−3 for Se-doping x = 0.2. Thermal conductivity analysis in comparison with the total thermal conductivity and the calculated electronic thermal conductivity revealed the lowest lattice thermal conductivity of 0.17 Wm−1K−1 for the Se-doping x = 0.2 after the correction for structural anisotropy factor (f). The highest thermoelectric figure of merit of 0.74 was achieved in this course of work.

Tracing source and palaeo‐weathering conditions of quartzose sandstone in the Cretaceous Cambay Basin: A combined petrographical, geochemical and geochronological approach

Based on detrital monazite dating, mineral chemistry of tourmaline and rutile, bulk rock geochemistry, modal analysis of petrographic and palaeocurrent data, this study tracks the source of quartzose sandstone within the Cretaceous succession of the Cambay Basin primarily to rocks within the Aravalli‐Delhi Fold Belt. Monazite geochronology shows predominant peaks around 506 ± 11 Ma, 905 ± 12 Ma and a minor peak at 750 ± 20 Ma, 1485 ± 30 Ma relating sediment sources to the Aravalli‐Delhi orogeny and Pan‐African orogeny. The petrographic modal analysis of the moderate‐to‐well‐sorted Himmatnagar Sandstone indicates at least 91% quartz, with minor feldspar and rock fragments. The mineral chemistry of tourmalines in Himmatnagar Sandstone matches with Li‐ and Ca‐poor granitoid, pegmatites, metapelites and quartz tourmaline rocks. The trace element content of rutiles in sandstones corresponds to metapelitic sources. Detrital monazite dates and mineral chemistry of tourmalines and rutiles pinpoint the sediment source to the South Delhi Supergroup of rocks. The dominance of rounded zircons and tourmalines and abraded quartz overgrowth in the Himmatnagar Sandstone indicate the recycling of sediments, possibly from the Marwar Supergroup. Palaeoclimatic proxies based on mineralogy and geochemistry, particularly, the high value (93–97) of mineralogical index alteration, indicate intense chemical weathering of the source rocks under humid climatic conditions. Therefore, the combination of factors, including the quartzo‐feldspathic source rocks, intense chemical weathering under humid climatic conditions and the recycling of sediments facilitated the formation of quartzose sandstone within the Himmatngar Sandstone in the Cambay Basin.

Typical Synoptic Patterns Responsible for Summer Regional Hourly Extreme Precipitation Events Over the Middle and Lower Yangtze River Basin, China

AbstractBased on the hourly rainfall gauge data and ERA5 reanalysis for the period 1980–2020, typical synoptic patterns responsible for summer regional hourly extreme precipitation events (RHEPE) over the middle and lower Yangtze River basin have been objectively identified using a circulation clustering method. It is found that the Meiyu front with different locations and intensities imbedded in the East Asian summer monsoon, and landfalling typhoons are the leading contributors. As the dominant synoptic pattern, the Meiyu front pattern is associated with ∼92% of the total RHEPE occurrence and can be categorized into a southerly strong‐Meiyu type and a northerly weak‐Meiyu type. The RHEPE occurrence shows a predominant morning peak associated with the southerly strong‐Meiyu type and a secondary late afternoon peak related to the northerly weak‐Meiyu type, in which the Meiyu front is pushed northward by the strengthened western North Pacific subtropical high accompanied by accelerated low‐level southwesterly flow.

Monitoring performance of slopes via ambient seismic noise recordings: Case study in a colluvium deposit

Long-term monitoring of slopes is of significance for engineering geology research and geo-disaster prevention. There is a growing need to develop fast, nondestructive and affordable techniques that can detect gradual and cyclic changes inside slopes. For this purpose, we propose a fast and low-cost computational framework based on processing the single-point ambient seismic noise recordings by the horizontal-to-vertical spectral ratio (HVSR) method. To test the efficiency of the proposed framework, we conduct a demonstration study in a road-cut slope in colluvium deposits in Southwest China. First, we carry out short-term ambient seismic noise surveys on the slope, delineate the shear wave velocity (Vs) structure of the slope, verify and establish this structure as the reference Vs model for the slope. Then we conduct the long-term monitoring of the ambient seismic noise on two profiles of the slope, calculate the HVSR curves and observe the time-dependent variations of the predominant peaks that reflect temporal changes of subsurface interfaces. Finally, we perform the Vs inversion to investigate changes in the Vs structure with rainfall. Through the monitoring, we identify the rainfall-induced slope failure and discover that both predominant frequency and shallow subsurface Vs of slope are negatively correlated with rainfall. The HVSR calculation, the predominant peak identification and the Vs inversion can all be implemented in minutes, which is much faster than the array-based surface wave method. The theoretical analysis and the demonstration application show that the framework we proposed in this study has great potential for monitoring changes in performance of slopes.

Late Triassic initial closure of the Mongol-Okhotsk Ocean in the western segment: Constraints from sedimentological, detrital zircon ages and paleomagnetic evidence

The Mesozoic evolution of the Mongol-Okhotsk Ocean (MOO) has significantly affected the configuration of the modern Asian continent. Although a scissor-like closure of the MOO has long been proposed, when and how the MOO closed are still hotly debated, especially the timing of initial closure of the MOO in its western segment, hindering our understanding of both the evolution of the MOO and tectonics of the northern Asian continent. In order to uncover the timing of initial closure of the MOO, we performed a multidisciplinary study in sedimentology, detrital zircon U-Pb dating and paleomagnetic on the Late Triassic clastic strata from the Tarvagatay Block and the Amuria Block (AMB) on the both sides of the Mongol-Okhotsk Suture. The upper Triassic strata on both sides of the suture were dominated by plant fossil-bearing alluvial-fluvial facies sediments, which unconformably overlain pre-Triassic geological units, indicating a terrestrial setting after the closure of the MOO. Detrital zircon U-Pb dating results revealed consistent age distribution patterns for samples from both sides of the suture with a predominant peak at ∼253–251 Ma and a secondary peak at ∼359–357 Ma, representing two main arc magmatic events during the bidirectional subduction of the MOO in the Late Devonian-Early Carboniferous and Late Permian-Early Triassic. Coeval Late Triassic paleomagnetic poles were obtained from the northern AMB and Tarvagatay Block, revealing a comparable paleolatitude of the AMB (∼31–33°) and Tarvagatay Block (∼32–34°) in the Late Triassic, arguing for that the western segment of the MOO should have closed at the Late Triassic. The compilation of sedimentology, detrital zircon U-Pb dating, magmatic and paleomagnetic evidence provides integrated constraints on the Late Triassic initial closure of the MOO in its western segment.

Thermoluminescent characteristics of UV-irradiated Aluminum nitride (AlN)

This paper presents results of studying the thermoluminescence (TL) properties of aluminum nitride (AlN) synthesized by chemical vapor deposition (CVD) method. Previously to study the TL properties, the phosphor was characterized by means of X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), photoluminescence (PL), and electron microscopy (EDS-SEM). TL studies were performed after ultraviolet (UV) irradiation using the whole spectrum of the xenon (Xe) lamp. XRD results show that AlN has a hexagonal crystalline structure. EDS-SEM analysis revealed the presence of oxygen (O) and Carbon (C) impurities in the powders. FT-IR spectroscopy lets us discuss the distribution of these impurities in the crystalline structure. The sample with 9.54% of C and 7.36% of O exhibits a TL glow curve with a predominant peak around 450 K, and according to the deconvolution method was found that the glow curve is composed by six peaks each one centered at 383, 446, 478, 540, 587 and 637 K. The TL response as a function of dose fits a logarithmic increasing function along the dose range studied: These results suggest that AlN is a promising material for application as a TL dosimeter for UV radiation.