Molecular Ratios Research Articles

Apportioning sources of natural and anthropogenic organic matter in sediment from Lake Shihwa: An integrated approach using molecular ratios and compound-specific stable-isotope analysis

We tested an integrated multi-isotopic analysis framework to quantitatively estimate anthropogenic organic matter (OM) loads in different land-use types of a watershed (Lake Shihwa, South Korea). The isotopic signatures of increased bulk-element abundances in urban areas and industrial complexes may reflect the mixed contributions of natural and anthropogenic sources. Together with the predominant abundance of n-alkanes and polycyclic aromatic hydrocarbons at both boundaries, specific indices derived from their abundance may be indicative of mixed contributions from terrestrial plants, petroleum, and combustion deposited through various pathways (e.g., atmospheric deposition, outfall pipes, and surface runoff). Based on these properties, compound isotopic signatures (δ13CC27+C29+C31, δ13CFl, δ13CPyr, δ13CBaA+Chry, δ13CIcdP, δ13CBghiP,) for both land-use types may provide significant evidence of an increase in anthropogenic derived-OM loads (> 90 %) in Lake Shihwa. This approach suggests that total organic carbon–weighted source apportionments can provide useful quantitative estimates of OM loads within complex river systems.

IGRINS Observations of WASP-127 b: H2O, CO, and Super-solar Atmospheric Metallicity in the Inflated Sub-Saturn

High-resolution spectroscopy of exoplanet atmospheres provides insights into their composition and dynamics from the resolved line shape and depth of thousands of spectral lines. WASP-127 b is an extremely inflated sub-Saturn (R p = 1.311 R Jup, M p = 0.16 M Jup) with previously reported detections of H2O and CO2. However, the seeming absence of the primary carbon reservoir expected at WASP-127 b temperatures (T eq ∼1400 K) from chemical equilibrium, CO, posed a mystery. In this manuscript, we present the analysis of high-resolution observations of WASP-127 b with the Immersion Grating Infrared Spectrometer on Gemini South. We confirm the presence of H2O (8.67σ) and report the detection of CO (4.34σ). Additionally, we conduct a suite of Bayesian retrieval analyses covering a hierarchy of model complexity and self-consistency. When freely fitting for the molecular gas volume mixing ratios, we obtain super-solar metal enrichment for H2O abundance of log10 X H2O = −1.23 −0.49+0.29 and a lower limit on the CO abundance of log10 X CO ≥–2.20 at 2σ confidence. We also report tentative evidence of photochemistry in WASP-127 b based upon the indicative depletion of H2S. This is also supported by the data preferring models with photochemistry over free-chemistry and thermochemistry. The overall analysis implies a super-solar (∼39× Solar; [M/H] = 1.59−0.30+0.30 ) metallicity for the atmosphere of WASP-127 b and an upper limit on its atmospheric C/O ratio as < 0.68.

A method for numerical simulation of shock waves in rarefied gas mixtures based on direct solution of the Boltzmann kinetic equation

The paper proposes an approach to numerical simulation of shock waves in rarefied gas mixtures on the basis of direct solution of the Boltzmann kinetic equation. Software for simulating the gas flows was developed. The structure of a shock wave in a binary gas mixture was computed with an accuracy controlled by the computational parameters. The computations were performed for various molecular masses ratios and Mach numbers. The total accuracy of at least 1.4% for the local values of the molecular densities and temperatures of the mixture components was achieved. Numerical simulation of a shock wave propagation through a periodically perforated surface was performed. The distributions of the macroscopic characteristics of the mixture components at various points in time were obtained. Unsteady areas of strong separation of the gas mixture components were discovered.

Hydrogeochemical dynamics under saltwater-freshwater mixing in a mangrove wetland over tidal cycles

Seawater and groundwater interactions shape the hydrogeochemical profile of mangrove aquifers, revealing how biogeochemical processes adapt to saline-freshwater mixing via the fluctuating patterns of key hydrochemical indicators and primary biogenic elements. This study, utilizing a multi-level monitoring profile spanning the entire submerged aquifer within a mangrove wetland, analyzed the spatiotemporal dynamics of DO, ORP, pH, alkalinity and biogenic elements (C, N, S). The results revealed that among the basic hydrochemical parameters, total alkalinity showed the most stable spatiotemporal distribution and was positively correlated with salinity. pH demonstrated a significant negative correlation with salinity, whereas the correlations of ORP and DO with salinity were not substantial. The discharge of terrestrial freshwater into the mangrove wetland is marked by hydrogeochemical reactions favoring the input of Mg2+ and DIC, with potential iron mineral precipitation within the aquifer. Spatial distribution of biogenic elements in the groundwater showed no apparent pattern across sampling periods. DOC concentrations ranged from 0.3 to 1.3 mmol/L. Three components of dissolved organic matter were identified using three-dimensional fluorescence spectroscopy, with high molecular weight components (C1 + C2) accounting for an average of 47 to 73 %. Both elevated DOC concentrations and high molecular weight component ratios were primarily found in shallow layers of dense mangrove areas, decreasing with depth. Concentrations of ammonia, nitrite, and nitrate varied dynamically, reflecting active biochemical processes in the shallow to mid-layers of the aquifer. Furthermore, sulfate and sulfide concentrations, ranging from 0 to 26 mmol/L and 0.4 to 576.8 μmol/L, respectively, underscore the interplay of biogeochemical reactions, especially sulfate reduction. These findings highlight valuable insights into the complex biogeochemical processes within mangrove aquifers and provide theoretical guidance for protecting the ecological health of mangrove wetlands.

JWST-TST High Contrast: Spectroscopic Characterization of the Benchmark Brown Dwarf HD 19467 B with the NIRSpec Integral Field Spectrograph

We present the atmospheric characterization of the substellar companion HD 19467 B as part of the pioneering James Webb Space Telescope Guaranteed Time Observer program to obtain moderate resolution spectra (R ∼ 2700, 3–5 μm) of a high-contrast companion with the NIRSpec integral field unit (IFU). HD 19467 B is an old, ∼9 Gyr, companion to a solar-type star with multiple measured dynamical masses. The spectra show detections of CO, CO2, CH4, and H2O. We forward model the spectra using Markov Chain Monte Carlo methods and atmospheric model grids to constrain the effective temperature and surface gravity. We then use NEWERA-PHOENIX grids to constrain nonequilibrium chemistry parameterized by K zz and explore molecular abundance ratios of the detected molecules. We find an effective temperature of 1103 K, with a probable range from 1000 to 1200 K, a surface gravity of 4.50 dex, with a range of 4.14–5.00, and deep vertical mixing, log10(K zz ), of 5.03, with a range of 5.00–5.44. All molecular mixing ratios are approximately solar, leading to a C/O ∼ 0.55, which is expected from a T5.5 brown dwarf. Finally, we calculate an updated dynamical mass of HD 19467 B using newly derived NIRCam astrometry, which we find to be 71.6−4.6+5.3MJup , in agreement with the mass range we derive from evolutionary models, which we find to be 63–75 M Jup. These observations demonstrate the excellent capabilities of the NIRSpec IFU to achieve detailed spectral characterization of substellar companions at high contrast close to bright host stars, in this case at a separation of ∼1.″6 with a contrast of 10−4 in the 3–5 μm range.

The application of unsupervised machine learning for the elucidation of the burial effect of lignin in peatland: Case of TMAH thermochemolysis

Lignin is one of the major components of organic macromolecules in peatland. Analysis of lignin in sediments is considered as a valuable tool for understanding peat vegetation as well as carbon cycle. It provides valuable perspectives on different sides such as occurrence of various vegetation types and the extent of decay in terrestrial organic material. Thermochemolysis technique using tetramethyl ammonium hydroxide (TMAH) was used for lignin analysis, in an ombrotrophic peatland. It specifically breaks of O-aryl bonds followed by methylation of the lignin components yielding phenolic subunits. Several discrepancies exist between TMAH thermochemolysis findings and those obtained from previous investigations with CuO oxidation. This could be explained by the specific pool of aryl ether, specifically targeted by the thermochemolysis, with discarding of C-C bonds. Hence, this would show the capacity of TMAH thermochemolysis to cleave oxidised lignin leaving lignin of fresh and preserved organic matter intact. The TMAH thermochemolysis method's efficiency in molecular characterization and lignin degradation was evaluated using principal component analysis (PCA). PCA reduced dimensionality and redundancy of component contributions, with the first two principal components accounting for 70.33 % of the total variance. PCA has reinforced the selectively of the thermochemolytic approach in targeting O-aryl bonds while maintaining C-C bonding of polyphenolic sub-units. Hence, two distinct oxidation phases: recent (acrotelm and mesotelm) and older (catotelm) have been revealed. PCA was applied to diagenetic and source vegetation proxies, revealing strong agreement among variables which is supported by the use of molecular ratios as indicators of organic matter source and dynamics in a peat core.

Pyrolytic conversion of glucose into hydroxymethylfurfural and furfural: Benchmark quantum-chemical calculations.

Quantum chemical methods have been intensively applied to study the pyrolytic conversion of glucose into hydroxymethylfurfural (HMF) and furfural (FF). Herein, we collect the most relevant mechanistic proposals from the recent literature and organize them into a single reaction network. All the transition structures (TSs) and intermediates are characterized using highly accurate ab initio methods and the possible reaction pathways are assessed in terms of the Gibbs energies of the TSs and intermediates with respect to β-glucopyranose, selecting a 2D ideal-gas standard state at 773 K to represent the pyrolysis conditions. Several pathways can lead to the formation of both HMF and FF passing through rate-determining TSs that have ΔG‡ values of ~49-50 kcal/mol. Both water-assisted mechanisms and nonspecific environmental effects have a minor impact on the Gibbs energy profiles. We find that the HMF → FF + CH2O fragmentation has a small ΔrxnG value and an accessible ΔG‡ barrier. Our computational results, which are in consonance with the kinetic parameters derived from lumped models, the results of isotopic labeling experiments and the reported HMF/FF molecular ratios, could be useful for modeling studies including on nonequilibrium kinetic effects that may render more information about product yields and the relevance of the various pathways.

Polycyclic aromatic hydrocarbons in ship breaking area and associated ecological risk assessment: evidence from the Sitakund ship-breaking area in Bangladesh.

Ship-breaking yards are recognized for releasing hazardous polycyclic aromatic hydrocarbons (PAHs), leading to severe environmental pollution in the sediment of ship-breaking areas. This study assessed the concentrations of 16 priority PAHs in surface sediments collected from the intertidal zone adjacent to the Sitakund ship-breaking yards. The samples underwent Soxhlet extraction and detection using PerkinElmer GC-Clarus 690 and MS-Clarus SQ8C with an Elite-5MS capillary column (30m × 0.25mm ID × 0.25µm). The study utilized PAH concentrations to reveal spatial distribution patterns, identify point sources, and assess potential toxicity. The total PAH concentration ranged from 1899.2 to 156,800.08ngg-1 dw, while the concentration of 7 carcinogenic PAHs ranged from 822.03 to 1899.15ngg-1 dw. High molecular weight PAHs dominated among the 16 PAHs, whereas low molecular weight PAHs, such as 2-ring PAHs, were negligible. Source characterization based on different molecular ratios suggested that PAHs in the area originated from pyrolytic processes related to ship dismantling, fishing activities, and water transportation for people. The observed PAH concentrations exceeded both national and international standards for sedimentary PAH levels, indicating significant ecological risks. The total TEQcarc values of sediment samples varied from 564.41 to 10,695.12ngg-1, with a mean value of 3091.25ngg-1. The study's findings underscore the immediate biological damage that PAH contamination in the Sitakund ship-breaking area could cause, emphasizing the need for effective control measures to ensure ecological and human safety.

Insights into the variations of polycyclic aromatic hydrocarbons and their nitrated and oxygenated derivatives in urban airborne PM2.5

Polycyclic aromatic hydrocarbons (PAHs) can be transformed into more toxic species in the atmosphere, but field evidence for their transformation remains rare. Here, polycyclic aromatic compounds (PACs), including PAHs and their nitrated and oxygenated derivatives (NPAHs and OPAHs), in fine particulate matter (PM2.5) were measured in the seasons at multiple locations in a megacity (Guangzhou, China). Molecular diagnostic ratios (MDRs), meteorological factors, and atmospheric oxidant measurements were employed to understand the atmospheric behaviors of PM2.5-bound PACs. The results indicated that similarities/differences in the short-term variations of PAC concentrations between the locations depended on their sources and seasons. The temporal trends in MDRs were more distinct than those in concentrations among the locations. Meteorological factors affected PAC concentrations through a similar pathway (demodulating loadings on PM). Their influence on the ratios can be explained by compounds’ atmospheric half-life, vapor pressure, or particle-size distribution. Temperature was the most powerful factor for both the concentrations and MDRs. Relative humidity was minor, but its positive influence on the reaction to OH radicals was appreciable. The dependence on PM2.5 concentrations suggests that PM plays a more significant role in the sorption or formation of N/OPAHs than in their parent compounds. The OH radical-initiated reaction is the major formation mechanism of N/OPAHs throughout the year, but substantial reactions to NO3 radical in autumn were observed due to high ozone levels. Multiple linear regression revealed that parent PAHs, NO2, and/or O3 are significant contributing factors to the secondary formation of N/OPAHs. Partial least squares-discriminant analysis showed the distinguishing characteristics of summer and autumn PM2.5-bound PACs. This study provides field evidence for the gaseous and heterogeneous reactions of PAHs.

Dried blood spot-based free sterol signatures in sitosterolemia diagnostics

BackgroundSitosterolemia is a rare inherited lipid metabolic disorder characterized by increased levels of plant sterols and accelerated atherosclerosis. Although early detection is beneficial for the prevention of disease progression, it is largely underdiagnosed by routine screening based on conventional lipid profiles. Materials and methodsA gas chromatography-mass spectrometry (GC–MS)-based profiling has been developed and validated to measure the levels of biologically active free sterols, including five endogenous sterols and three plant sterols (sitosterol, campesterol, and stigmasterol) in dried blood spot (DBS). ResultsWithin- and between-run precisions were 1.4–11.1 % and 2.2–14.1 %, respectively, while the accuracies were all 86.3 ∼ 121.9 % with the correlation coefficients (r2) > 0.988 for all the sterols. In the patients (four girls and two boys, 6.5 ± 2.8 years), sitosterol levels were significantly increased, with an optimal cut-off value of 2.5 µg/mL distinguishing them from ninety-three age-matched healthy children. A cut-off value of 31.9 µg/mL differentiated the patients from six ABCG5/ABCG8 heterozygous carriers. In addition, the molecular ratios of sitosterol to cholesterol, desmosterol, and 7-dehydrocholesterol provided excellent cut-off values of 26.3, 67.6, and 21.6, respectively, to distinguish patients from both healthy controls and heterozygous carriers. ConclusionsThe novel DBS-based GC–MS profiling of free sterols accurately identified patients with sitosterolemia, with a performance comparable to that of a serum assay. The DBS profiling could be more feasible method in clinical practice as well as population screening programs, and it can provide diagnostic cut-off values for individual plant sterols.

Decoding the Impact of Molecular Configuration on High‐Efficiency Blue Hot Exciton Emitters

AbstractRealizing highly efficient organic light‐emitting diodes (OLEDs) based on “hot exciton” emitters is crucial for the widespread use of purely organic electroluminescence. Herein, it is demonstrated that the radiative decay rate, modulated by molecular configuration, plays a vital role in determining the optoelectronic properties of hot exciton materials. The proof‐of‐concept isomers, TPA‐1IPCN and TPA‐3IPCN, and TPA‐1IANCN and TPA‐3IANCN are intentionally designed and successfully synthesized. By employing a novel donor–acceptor–acceptor (D–A'–A) molecular architecture, implementing a molecular isomerization strategy, incorporating diverse steric hindrance moieties, and strategically manipulating the positioning of functional groups, precise modulation of the molecular configuration can be achieved to enable accurate regulation of the radiative decay rate. Consequently, various optoelectronic properties, including photoluminescent wavelength, photoluminescence quantum yield, fluorescence lifetime, packing mode in aggregated state, and molecular horizontal dipole ratios in films, undergo significant modifications. As a result, non‐doped blue OLED based on TPA‐1IPCN exhibits outstanding maximum external quantum efficiency (EQE) of 10.3% with minimal efficiency roll‐off—one of the highest reported values for blue OLEDs based on hot exciton materials.

Deciphering the imprint of active galactic nucleus feedback in Seyfert galaxies. Nuclear-scale molecular gas deficits

We study the distribution of cold molecular gas in the circumunuclear disks (CND; $r pc) of a sample of 64 nearby L $=7-45 Mpc) disk galaxies ---including 45 active galactic nuclei (AGN) and 19 nonAGN--- for which high-spatial-resolution (median value $ pc) multiline CO interferometer observations have been obtained at millimeter wavelengths with the Atacama Large Millimeter Array (ALMA) and/or Plateau de Bure Interferometer (PdBI). We decipher whether or not the concentration and normalized radial distribution of cold molecular gas change as a function of X-ray luminosity in the 2--10 keV range X $) in order to analyze the imprint left by AGN feedback. We also look for similar trends in the concentration and normalized radial distribution of the hot molecular gas and in the hot-to-cold-molecular gas mass ratio in a subset of 35 galaxies using near-infrared (NIR) integral field spectroscopy data obtained for the H$_2$ 1-0 S(1) line. We find a significant turnover in the distribution of the cold molecular gas concentration as a function of X-ray luminosity with a breakpoint that divides the sample into two branches: (1) the `AGN build-up branch'' ($L_ X pm0.3 $erg s$^ $) and (2) the ``AGN feedback branch'' ($L_ X pm0.3 $erg s$^ $) . Lower-luminosity AGN and nonAGN of the AGN build-up branch show high cold molecular gas concentrations and centrally peaked radial profiles on nuclear ($r pc) scales. Higher-luminosity AGN of the AGN feedback branch show a sharp decrease in the concentration of molecular gas and flat or inverted radial profiles. The cold molecular gas concentration index ($CCI$) --- defined as the ratio of surface densities at $r pc ($ gas $) and $r pc $( gas $), namely $CCI gas gas $)--- spans a 0.63 dex range, equivalent to a factor simeq 4-5, between the galaxies lying at the high end of the AGN build-up branch and the galaxies showing the most extreme nuclear-scale molecular gas deficits in the AGN feedback branch. The concentration and radial distributions of the hot molecular gas in our sample follow qualitatively similar but less extreme trends as a function of X-ray luminosity. As a result, we find higher values of hot-to-cold molecular gas mass ratios on nuclear scales in the highest luminosity AGN sources of the AGN feedback branch. These observations confirm ---with a three times larger sample--- previous evidence found in the context of the Galaxy Activity Torus and Outflow Survey (GATOS) that the imprint of AGN feedback on the CND-scale distribution of molecular gas is more extreme in higher luminosity Seyfert galaxies of the local Universe.

Myrcene-itaconate Diels-Alder cycloadducts in the synthesis of photocurable polyesters for the 3D printing of fully biobased resins

Photopolymerization-based 3D printing techniques, such as vat photopolymerization (VP), unfortunately still strongly rely on the use of fossil-based (meth)acrylate monomers for the formulation of photo hardening resins. Because of that many researchers have recently directed their efforts towards the replacement of methacrylic and acrylic acid derivatives with biobased counterparts. Indeed, in this work, we introduce a novel approach for producing sixteen fully biobased resins for VP, based on photocurable polyesters synthesized starting from bio-sourced reagents. Itaconic acid, widely recognized as an effective biobased photocurable monomer, and myrcene, a terpene consisting of two isoprene units, are employed in a Diels-Alder cycloaddition to achieve a co-monomer (My-DMI) for the new photocurable polyesters. By exploring various molecular weights, diols and ratios between itaconate and My-DMI, we synthesized eight different polyesters. By combining these with appropriately designed reactive diluents, we successfully tuned the mechanical properties of the 3D printed materials, ranging from very flexible to extremely rigid, depending on the diol chain length and itaconate contents. Additionally, we provide a detailed evaluation of the biobased content of each formulation according to the OK BIOBASED labelling for plastics, finding biobased content as high as 97 % in most cases.

The Ice Chemistry in Comets and Planet-forming Disks: Statistical Comparison of CH3OH, H2CO, and NH3 Abundance Ratios

Comets are frozen remnants of our solar system’s formation, and comparing their chemical composition to that of planet-forming systems can reveal crucial insights about our origins, potentially answering one of the most challenging questions in planetary science, i.e., whether cometary material was mainly inherited from the protosolar nebula or reprocessed during the solar system formation. Here we provide the first statistical analysis of methanol, formaldehyde, and ammonia abundances in 35 comets and 11 protostellar solar analogs and planet-forming disks. We show that comets from different dynamical families have comparable compositions on average, implying that their chemistry is preserved even after formation. While abundances retrieved from infrared and (sub)millimeter ground-based observations are in agreement, there are significant differences with those obtained via mass spectroscopy for 67P/Churyumov–Gerasimenko, target of the ESA-Rosetta mission; we discuss the implication of relying solely on the latter data for comparisons with disk abundance ratios. Finally, we find a significant difference in the [CH3OH]/[H2CO] ratio in comets observed within or farther than 1 au from the Sun, suggesting that temperature-activated mechanisms can enhance the H2CO production in the coma; this bias can strongly influence our understanding of comet chemistry in the context of planet formation. When compared to planet-forming systems, the [CH3OH]/[H2CO] and [NH3]/[CH3OH] molecular abundance ratios in comets are consistent with those measured in Class 0 hot corinos and in the inner regions of Class II disks, hence suggesting an inheritance scenario.

Porous PVDF composites with ultralow percolation threshold for wide-range dynamic and static pressure sensing

Porous conductive polymer composites are very attractive for static pressure sensing due to high sensitivity and good elasticity contributed by the porous structure, while they are hard to detect dynamic pressure. Herein, we report a porous conductive poly (vinylidene fluoride) (PVDF) composite capable of detecting static and dynamic pressure over a pressure range of 0–1 MPa, which was fabricated by melt mixing PVDF, polyethylene oxide (PEO) and carbon nanofillers, followed by etching PEO with water. Such porous PVDF composites have a very low percolation threshold (0.035 wt%) of carbon nanostructures (i.e., branched carbon nanotubes) thanks to the selective distribution of conductive fillers in the pore wall after etching. At the same time, the pore size and porosity of the porous PVDF composites can be tuned by the molecular weight (Mw) and blending ratios of two polymers, leading to the kinetically-tailorable blend morphology for tunable mechanical and electrical properties. The as-fabricated porous PVDF composites with a good combination of mechanical properties and electrical conductivities, which can be used as pressure sensors toward wide-range (0–1 MPa) dynamic and static pressure sensing. Such pressure sensors demonstrate potential applications in detecting the degree of finger bending, distinguishing the walking and running, and monitoring a series of technical movements in playing soccer, i.e., static and dynamic exercises.

Source identification of polycyclic aromatic hydrocarbons (PAHs) in soils around crude oil contaminated area in Ohaji/Egbema, Imo State

ABSTRACT This study aims to determine the source of polycyclic aromatic hydrocarbons (PAHs) in the soils surrounding an area in Ohaji/Egbema, Imo State, that has been contaminated by crude oil. Soil samples were collected in the study area using a soil auger at a depth of 0–20 cm at three sampling locations (sample A, sample B, and sample C) in the Mmahu community in Ohaji/Egbema. In each of the sampling locations, twenty sub-samples were collected from twenty sampling points and pooled together to form representative samples for each of the sampling locations. Prior to GC-MS analysis, the composite samples were air-dried, sieved through a 2-mm mesh, and then kept in pet bottles that had been previously cleaned. The GC-MS investigations were carried out using a Shimadzu Model 2010 GC-MS (Shimadzu, Japan) fitted with an HP-5 MS fused silica column. This was used to quantify the 16 USEPA priority PAHs in the studied soils. The sum of the 16 USEPA priority PAHs in the sample locations ranged from 0.0192 mg/kg in the control sample to 10.73 mg/kg in sample A. Compared to high molecular weight PAHs (4–6 rings), the total concentration of low molecular weight PAHs (2–3 rings) was found to be substantially greater. According to the PAH molecular diagnostic ratio, all sampling points had low to high molecular mass ratios >1, which suggests that the origin of the PAH contamination was petrogenic. The petrogenic source of contamination was attributed to oil spillage around the study area. The knowledge of source identification of PAHs in soils helps in the determination of the most appropriate remediation strategy in order to prevent further contamination and minimise the risks to human health and the environment.

U3 snoRNA inter-regulates with DDX21 in the perichromosomal region to control mitosis

U3 snoRNA is essential for ribosome biogenesis during interphase. Upon mitotic onset, the nucleolus disassembles and U3 snoRNA relocates to the perichromosomal region (PR) to be considered as a chromosome passenger. Whether U3 controls mitosis remains unknown. Here, we demonstrate that U3 snoRNA is required for mitotic progression. We identified DDX21 as the predominant U3-binding protein during mitosis and confirmed that U3 snoRNA colocalizes with DDX21 in the PR. DDX21 knockdown induces mitotic catastrophe and similar mitotic defects caused by U3 snoRNA depletion. Interestingly, the uniform PR distribution of U3 snoRNA and DDX21 is interdependent. DDX21 functions in mitosis depending on its PR localization. Mechanistically, U3 snoRNA regulates DDX21 PR localization through maintaining its mobility. Moreover, Cy5-U3 snoRNA downsizes the fibrous condensates of His-DDX21 at proper molecular ratios in vitro. This work highlights the importance of the equilibrium between U3 snoRNA and DDX21 in PR formation and reveals the potential relationship between the PR assembly and mitotic regulation.

Atmospheric polycyclic aromatic hydrocarbons in India: geographical distribution, sources and associated health risk-a review.

Atmospheric distribution of polycyclic aromatic hydrocarbons and associated human health risks have been studied in India. However, a comprehensive overview is not available in India, this review highlights the possible sources, and associated cancer risks in people living in different zones of India. Different databases were searched for the scientific literature on polycyclic aromatic hydrocarbons in ambient air in India. Database searches have revealed a total of 55 studies conducted at 139 locations in India in the last 14years between 1996 and 2018. Based on varying climatic conditions in India, the available data was analysed and distributed with four zone including north, east, west/central and south zones. Comparatively higher concentrations were reported for locations in north zone, than east, west/central and south zones. The average concentrations of ∑PAHs is lower in east zone, and concentrations in north, west/central and south zones are higher by 1.67, 1.47, and 1.12 folds respectively than those in east zone. Certain molecular diagnostic ratios and correlation receptor models were used for identification of possible sources, which aided to the conclusion that both pyrogenic and petrogenic activities are the mixed sources of PAH emissions to the Indian environment. Benzo(a)pyrene toxicity equivalency for different zones is estimated and presented. Estimated Chronic daily intake (CDI) due to inhalation of PAHs and subsequently, cancer risk (CR) is found to be ranging from extremely low to low in various geographical zones of India.

Investigation of 200 anthropogenic activities in a representative alpine peatland in the Altay Mountains, northwestern China

Peatlands records can be used to reconstruct and understand the history of environmental evolution, as well as a more accurate reflection of human activities. The black carbon (BC) and polycyclic aromatic hydrocarbons (PAHs) are ideal natural archives of anthropogenic activities. To identify the information of anthropogenic activities recorded by peatlands in the middle and high latitudes of the alpine mountains in the arid and semi-arid regions of China. this study analyzed the concentrations of BC, δ13C ratios of BC, PAHs, and molecular diagnostic ratios of PHAs (including Benzo(a) anthracene (BaA), Chrysene (Chr), fluoranthene (Flt), anthracene (Ant), phenanthrene (Phe), Benzo(a) pyrene (BaP), and pyrene (Pyr) in a 30-cm peat profile from the Altay Mountain, northwestern China. Our results revealed concentrations of BC from 11.71 to 67.5 mg·g−1, and PAHs from 168.09 to 263.53 ng·g−1. The δ13CBC value ranged from − 31.37 to − 26.27‰, with an average of − 29.54‰, indicating that the BC mainly comes from biomass combustion. The ratios of BaA/(BaA + Chr), Flt/(Flt + Pyr), and Ant/(Ant + Phe) exceeded 0.35, 0.5, and 0.1, respectively, revealing that the PAHs pollutants mainly originated from the combustion of biomass and fossil fuel burning. Furthermore, based on these findings and our knowledge of social development in Altay, industrial transport and tourism have influenced the emission, transport, and deposition of BC and PAH in peatlands in the Altay mountains since the 1980s. After 1980, pollutant concentrations decreased with the implementation of environmental policies. The results not only reveal the influence of anthropogenic activities on the sedimentary characteristics of peatlands in the Altay Mountains, but also provide an important theoretical basis for the conservation of fragile mountain peatlands.

Distribution, levels, sources and risk assessment of polycyclic aromatic hydrocarbons in the bottom sediments of a Mediterranean river under multiple anthropopressures (Soummam River), Algeria

The Soummam River, a vital watercourse in Algeria is threatened by anthropogenic activities despite its protected wetland status. This study is the first to assess sediment pollution in the Soummam River, examining levels, compositions, sources of 16 PAHs and their effects on the environment and human health. Analysis employing Principal Component Analysis (PCA) and molecular diagnostic ratios pointed to petrogenic sources, likely stemming from petroleum leaks originating from aging pipeline and vehicles, as well as pyrogenic sources arising from vehicle exhaust and biomass combustion. Environmental and health risks were assessed through risk quotients (RQ), Sediments Quality Guidelines (SQG) and Total Lifetime Cancer Risk (TLCR). Ecological risk was found to range from moderate to high, with anticipated biological impacts, while cancer risk was deemed low. Toxicity assessment, measured by TEQ, revealed that the majority of monitoring stations exceeded safe levels. Consequently, urgent action by local authorities is warranted to implement ecosystem rehabilitation measures.