Total Ion Research Articles

Narcissus cv. Hawera Leaves' Extract Cleaves DNA in Chlamydomonas reinhardtii by Inducing DSBs

The aim of this study is to go inside the mode of action of Narcissus cv. Hawera leaves' extract on Chlamydomonas reinhardtii by analyzing its chemical composition, genotoxic, mutagenic, and DNA damaging effects.
 GC/MS analysis of the methanol extract shows that alkaloids comprise about 23.93% of the total ion current (TIC). Considering the alkaloid pattern, lycorine is the major alkaloid (8.53% of TIC), followed by 6-epi-mesembrenol (4.59% of TIC), galanthamine (2.63% of TIC), and mesembrenone (2.01% of TIC). Other compounds in the extract are mono- and di-saccharides, organic acids, and fatty acids.
 Based on our experiments, both well-expressed genotoxic and DNA damaging potential of Narcissus cv. Hawera total leaves' extract was revealed for the first time. The most pronounced effect is obtained after the treatment with concentrations equal to or higher than 500 μg/ml. Cell survival decrease in a dose-dependent manner correlates with increased levels of induced DNA double-strand breaks (DSBs) but does not correspond with statistically confirmed mutagenic action. A good correlation is obtained between the levels of DSBs induced and cell survival rate.
 Here, for the first time, experimental evidence that Narcissus cv. Hawera leaves' extract can cleave DNA of Chlamydomonas reinhardtii inducing DSBs was reported by us. Our finding could be considered a good reason for further investigation of its biocidal capacity on other test systems for the purposes of “green” practice.

Metabolite profiling and histochemical localization of alkaloids in Hippeastrum papilio (Ravena) van Scheepen

Hippeastrum papilio (Amaryllidaceae) is a promising new source of galanthamine - an alkaloid used for the cognitive treatment of Alzheimer's disease. The biosynthesis and accumulation of alkaloids are tissue - and organ-specific. In the present study, histochemical localization of alkaloids in H. papilio's plant organs with Dragendorff's reagent, revealed their presence in all studied samples. Alkaloids were observed in vascular bundles, vacuoles, and intracellular spaces, while in other plant tissues and structures depended on the plant organ. The leaf parenchyma and the vascular bundles were indicated as alkaloid-rich structures which together with the high proportion of alkaloids in the phloem sap (49.3% of the Total Ion Current – TIC, measured by GC-MS) indicates the green tissues as a possible site of galanthamine biosynthesis. The bulbs and roots showed higher alkaloid content compared to the leaf parts. The highest alkaloid content was found in the inner bulb part. GC-MS metabolite profiling of H. papilio's root, bulb, and leaves revealed about 82 metabolites (>0.01% of TIC) in the apolar, polar, and phenolic acid fractions, including organic acids, fatty acids, sterols, sugars, amino acids, free phenolic acids, and conjugated phenolic acids. The most of organic and fatty acids were in the peak part of the root, while the outermost leaf was enriched with sterols. The outer and middle parts of the bulb had the highest amount of saccharides, while the peak part of the middle leaf had most of the amino acids, free and conjugated phenolic acids.

Ion-induced surface effects on soda-lime, amorphous silica (aSiO2) and silicon (100) substrates with 1.5 MeV Cu ion implantation

Soda-lime, silica and silicon (100) substrates were implanted with 1.5 MeV Cu+ ions with observable macroscopic surface effects. All substrates were irradiated at 70°, at 200-nA currents, in room temperature conditions, and for a total ion fluence between 3×1016 and 2×1017 ions cm−2. Surface characterization was carried out using SEM and AFM. Changes on the morphology result in the emergence of surface structures resembling ripples in the early stage which evolve into complex wrinkling structures at high ion doses. The formation and growth of surface patterns may be elucidated in terms of low and medium energies theories.

Characterization of the Volatile Constituents of Plai (Zingiber purpureum) by Gas Chromatography-Mass Spectrometry.

Zingiber purpureum Roscoe, known as plai in Thailand, is a perennial plant of the Zingiberaceae family and has traditionally been used in Southeast Asian countries to treat inflammation, pain, and asthma. In this study, we performed the characterization of the volatile constituents in ethyl acetate extracts of plai. Ethyl acetate extracts derived from the rhizomes of plai were subjected to gas chromatography-mass spectrometry, and the key peaks in the total ion current chromatograms were annotated or identified. In total, twenty-one compounds were identified using isolation procedures or standards, and nine compounds were annotated by comparing their Kovats retention index (RI) and electron ionization (EI) mass spectra with those in the literature. Most of the identifications were inconsistent with the tentative annotations found via library search and suggested that some peaks were incorrectly assigned in previous studies. Thus, to avoid further misannotations and contribute to the research on dereplication, the RI value, EI mass spectral data, and NMR spectroscopy data of the isolated compounds are reported.

Optimization of a carbon adsorption/HS-GC–MS method for ignitable liquids classification from fire debris

The main goal of any fire investigation is to find the origin and cause of fire. Fire is commonly initiated or accelerated by using ignitable liquids (ILs). The analysis of fire debris can contribute to the determination of the origin of the fire. In this study, the thermal desorption of IL residues (ILRs) from activated charcoal strips (ACS) was optimized prior to headspace- gas chromatography- mass spectrometry (HS-GC–MS) analysis for the identification and classification of ILRs in fire debris samples. A Box-Behnken Design (BBD) coupled with Response Surface Methodology (RSM) were used to determine the optimized conditions in the following ranges: incubation temperature (80–140 ˚C), incubation time (30–60 min), and agitation speed (250–750 rpm). The sum of the differences between the total ion spectrum (TIS) of gasoline and diesel was used as dependent variables. The quadratic model was significant with a p- value of 0.0061 and a coefficient of determination equals to 0.911. RSM revealed that an increase in incubation temperature and agitation speed increases the response. The optimized conditions were 140 °C and 750 rpm. Further optimization of the incubation time was studied by analyzing fire debris samples at different times (5–30 min) and 5 min was determined as the optimum condition. The final optimized conditions were applied in combination with chemometrics for the characterization of fire debris samples burned with different ILs. The obtained results demonstrate the feasibility of the method in fire debris analysis which avoids the use of organic solvents providing a greener and faster alternative method.

Machine Learning Method to Explore the Correlation between Fly Ash Content and Chloride Resistance.

Chloride ion corrosion has been considered to be one of the main reasons for durability deterioration of reinforced concrete structures in marine or chlorine-containing deicing salt environments. This paper studies the relationship between the amount of fly ash and the durability of concrete, especially the resistance to chloride ion erosion. The heat trend map of total chloride ion factor correlation displayed that the ranking of factor correlations was as follows: sampling depth > cement dosage > fly ash dosage. In order to verify the effect of fly ash dosage on chloride ion resistance, three different machine learning algorithms (RF, GBR, DT) are employed to predict the total chloride content of fly ash proportioned concrete with varying admixture ratios, which are evaluated based on R2, MSE, RMSE, and MAE. The results predicted by the RF model show that the threshold of fly ash admixture in chlorinated salt environments is 30-40%. Replacing part of cement with fly ash in the mixture of concrete below this threshold of fly ash, it could change the phase structure and pore structure, which could improve the permeability of fly ash concrete and reduce the content of free chloride ions in the system. Machine learning modeling using sample data can accurately predict concrete properties, which effectively reduce engineering tests. The development of machine learning models is essential for the decarbonization and intelligence of engineering.

The impacts of different seasons on macroinvertebrate community structure and functional diversity in the Jingui River, China

Species diversity and functional diversity indices reflect the variations of community structure and their responses to environmental stress. This study clarifies the biodiversity of macroinvertebrates in the Jingui River of Shenzhen and their response to the aquatic environment across different seasons. Utilizing ten functional traits, we conducted a seasonal survey at ten sampling points to examine changes in macroinvertebrate species and functional diversity, along with their relationships with environmental variables in the JGR. The results of the study demonstrated that the species and functional diversity of macroinvertebrates were significantly affected by season. Redundancy analysis indicated that water velocity, hydrogen ion concentration, turbidity, water depth, and total nitrogen were the most important factors for macroinvertebrate functional diversity. Moreover, structural equation modeling demonstrated that seasonal variations in total nitrogen, ammonia nitrogen, nitrate nitrogen, conductivity, water velocity, and hydrogen ion concentration directly or indirectly impacted the species diversity and functional diversity of macroinvertebrates. This study provides valuable information into the seasonal variation characteristics of macroinvertebrate communities, contributing to a more comprehensive understanding of biodiversity crucial for maintaining river ecosystem functioning and stability.

Phytochemical Characterization and Anticancer Screening of Cladophora goensis and Cladophora glomerata Extracts

Background Cladophora goensis and Cladophora glomerata has been widely identified in the Indian Oceans. Marine algae have been identified as potential pharmacological agents useful in the treatment of diabetes, hypertension, infections, and cancers. Objectives The present study aimed to evaluate the phytochemicals in C. goensis and C. glomerata using gas chromatography-mass spectroscopy (GC-MS), and to study the molecular interactions with cancer-related proteins using molecular docking techniques. Materials and methods GC-MS analysis was done using electron impact ionization at 70eV and the data was evaluated using total ion count for compound identification and quantification. AutoDock 4.0 version was used for the molecular docking analysis. Results The methanolic extracts of algae when subjected to GC-MS analysis, 19 compounds from C. goensis and 11 phytocompounds from C. glomerata were identified. The significant molecular interactions of phytochemicals of C. goensis (6-nitro-3 H-quinazolin-4-one, Isoquinoline, 1,2,3,4-tetrahydro-7-methoxy-2-methyl-8-(phenyl methoxy) and 9-Decen-1-ol, pentafluropropionate) and C. glomerata (phytol, palmitic acid, and octadec-9-enoic acid) against human epidermal growth factor receptor (4WRG), poly (ADP-ribose) polymerase-1 (4UND), human estrogen receptor alpha ligand-binding domain (3ERT), human peroxisome proliferator-activated receptor alpha ligand-binding domain (3VI8), and human topoisomerase (1EJ9) have been demonstrated. Conclusion The phytochemicals of methanolic extracts of C. goensis and C. glomerata showed potential interactions with cancer-related proteins.

Feature of Diurnal Double Maxima in the Topside Ionosphere Observed by ICON

AbstractThis study investigates the diurnal variation of topside ionospheric plasma density using the Ionospheric Connection Explorer (ICON) observations from May to July in 2020 and 2021. The total ion density exhibits daytime double‐maxima (DDM) patterns, also known as “bite‐out” at magnetic latitudes from 10°S to 20°N and longitudes of 180°–276°E, but a single peak in other longitudes. The total ion density between 180° and 276°E reaches its first peak around 12 LT (Local Time) in both hemispheres and the second peak at 14–15 LT in the Northern Hemisphere, gradually shifting to around 16–17 LT in the Southern Hemisphere. The formation of the first peak is mainly influenced by vertical plasma drift, while the second peak is associated with both neutral wind and vertical plasma drift. Furthermore, this study provides direct observational evidence for the influence of neutral winds on the longitude and latitude differences of the topside DDM. Stronger southward magnetic meridional winds and vertical plasma drifts are observed at approximately 11–15 LT in the longitude sector with DDM compared to other longitudes, leading to a valley of ion density in the Southern Hemisphere around 15 LT. In the Northern Hemisphere, ion density continues to accumulate to form a second peak at 15 LT.

Photodissociation Dynamics of the Highly Stable ortho-Nitroaniline Cation.

0rtho-Nitroaniline (ONA) is a model for the insensitive high explosive 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) that shares strong hydrogen bonding character between adjacent nitro and amino groups. This work reports femtosecond time-resolved mass spectrometry (FTRMS) measurements and theoretical calculations that explain the high stability of the ONA cation compared with related nitroaromatic molecules. Ab initio calculations found that the lowest-lying electronic excited state of the ONA cation, D1, lies more than 2 eV above the ground state, and the energetic barriers to rearrangement and dissociation reactions exceed this D1 energy. These theoretical results were confirmed by FTRMS pump-probe measurements showing that (1) fragment ions represented less than 30% of the total ion yield when a 1014 W cm-2, 1300 nm, 20 fs pump pulse was used to ionize ONA; and (2) 3.1 eV (400 nm) photons were required to induce dissociation of the ONA cation. Stronger coupling between the ground D0 and excited D4 states of the ONA cation at the geometry of neutral ONA resulted in a transient enhancement of fragment ion yields at <300 fs pump-probe delay times, prior to relaxation of the ONA cation to its optimal geometry.

Photoionization of Nitrile-substituted Naphthalene and Benzene: Cation Spectroscopy, Photostability, and Implications for Photoelectric Gas Heating

We investigate the vacuum ultraviolet (VUV) photodynamics of gas phase 1- and 2-cyanonaphthalene and cyanobenzene, recently detected in the Taurus molecular cloud, by combining synchrotron radiation and a double imaging electron/ion coincidence setup. The high-resolution threshold photoelectron spectra (TPES) of all three molecules are obtained experimentally from which the adiabatic ionization energies are reported with very high accuracy, particularly for 2-cyanonaphthalene, for which no data exist at this level of precision. Theoretical calculations are performed to compare with the TPES for the ground electronic state of the cations. Furthermore, the different features observed in the extended TPES have been assigned to the different molecular orbitals with the help of the outer valence Green's function calculations. The present experiments also shed light on the kinetic energy distribution of the photoelectrons as a function of the incident photon energy, to describe their contribution to the photoelectric heating effect in the interstellar medium. In this context, we show how kinetic energy distributions can be obtained from our data for any given photon energy, such as the omnipresent Lyα line, or any given interstellar radiation field (ISRF). In addition, from the total ion yields, we estimate the photorates for a few ISRFs. Finally, we discuss the photodissociation of the two cyanonaphthalenes, quoting the activation energies of the dissociation channels with the help of Rice–Ramsperger–Kassel–Marcus modeling. It is observed that CN substitution does not cause any appreciable change to the VUV dissociative photoionization relaxation channel.

Selective adsorption in ion exchange membranes: The effect of solution ion composition on ion partitioning

Electrodialysis is a water desalination technology that enables selective separation of ions, making it a promising solution for sustainable water reuse. The selectivity of the process is mainly determined by the properties of ion exchange membranes that can vary depending on the composition of ions in water, such as water uptake and charge density. In this work, we studied selective adsorption of Na+ and K+ ions in various ion exchange membranes considering the effect of solution ion composition on membrane water volume fraction. For that purpose, we conducted membrane adsorption experiments using solutions with Na+ and K+ ions with different ion compositions including Li+, Ca2+ or Mg2+ ions at different concentrations (0.001 – 0.25 M). The experiments showed that with the total ion concentration and the amount of divalent ions in solution, the membrane water volume fraction decreases while the selective adsorption of the smaller (hydrated) K+ ions over the Na+ ions in the membrane increases. We developed a theoretical framework based on Boublik-Mansoori-Carnahan-Starling-Leland (BMCSL) theory to describe the effect of membrane water volume fraction on selective adsorption of the ions by including volumetric effects, such as size exclusion. The developed framework was used to describe ion partitioning results of the membrane adsorption experiments. In addition, the effect of solution ion composition on selective ion removal during electrodialysis operation was evaluated using experimental data and theoretical calculations. The results of this study show that considering volumetric effects can improve the ion partitioning description in ion exchange membranes for solutions with various ion compositions.

Fluorine mass balance analysis in wild boar organs from the Bohemian Forest National Park

Wild boars have been reported as bioindicators for per- and polyfluoroalkyl substances (PFAS) in a variety of studies. However, data about PFAS levels in wild boars from sites with limited industrial and general human activity is scarce. In this study, wild boar (Sus scrofa) organs from the Bohemian Forest National Park (Czech Republic) were used as bioindicators for PFAS pollution. In this work, 29 livers and 24 kidneys from 30 wild boars (0.5–5 years) were investigated using a fluorine mass balance approach. For this, the samples were measured using high performance liquid chromatography with electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS), targeting 30 PFAS, including legacy and replacement PFAS, direct total oxidisable precursor assay (dTOPA) and combustion ion chromatography (CIC). Perfluorocarboxylic acids (PFCAs) from C7 to C14 and perfluorooctanesulfonic acid (PFOS) were detected in >50 % of samples. In the livers, PFCAs dominated the profile with median concentrations of 230 μg/kg for perfluorononanoic acid (PFNA) and 75 μg/kg perfluorooctanoic acid (PFOA). PFOA and PFNA concentrations in the livers were one order of magnitude higher than in livers from wild boars caught in rural NE Germany considered as background concentration. PFOS in liver contributed only 30 % to the Σc(PFASTarget) with a median concentration of 170 μg/kg. Kidneys and livers contain an average of 2460 μg F/kg and 6800 μg F/kg extractable organic fluorine (EOF) respectively. Σc(PFASTarget) add up to a maximum of 10 % of the extractable organic fluorine. After oxidisation of the samples, PFOA, PFNA and Σc(PFASdTOPA) increased in livers, but could not explain the EOF. The elevated concentration of PFOA and PFNA may indicate differences in biomagnification for different habitats or an unidentified PFAS source in proximity to the national park.

Near-edge x-ray absorption fine structure spectra and specific dissociation of small peptoid molecules.

In this study, the total ion yield near-edge x-ray absorption fine structure spectra of four similar peptoid molecules, which differ in the numbers and positions of methyl groups, were investigated experimentally and theoretically. At each excitation energy, the intensity and branching ratio of each ionic product were measured. At a few resonant excitation energies, a specific dissociation of the C-CO bond at the nitrogen and oxygen K-edges and of the N-CO bond at the carbon K-edge was dominant, which correlated well with the predicted destination antibonding orbitals of the core electron excitation. These specific dissociation mechanisms of small peptoid molecules could provide insights into similar phenomena that occur in peptide molecules.

Method validation and characterization of stress degradation products of azelastine hydrochloride using LC-UV/PDA and LC-Q/TOF-MS studies.

Azelastine HCl is a second-generation H1 -receptor antagonist approved by the US Food and Drug Administration (US FDA) for treating seasonal allergic rhinitis and non-allergic vasomotor rhinitis. This study encompasses the validation of a liquid chromatography-ultra violet photo diode array (LC-UV/PDA) method for the drug and its extension to liquid chromatography/quadrupole time-of-flightmassspectrometry (LC-Q/TOF-MS) studies for identification and characterization of various stress degradation products of the drug. Stress degradation of azelastine HCl was undertaken under the International Council for Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) prescribed conditions of hydrolytic, photolytic, oxidative, and thermal stress. The degraded drug solutions were analyzed using Ultra Performance Liquid Chromatography (UPLC) employing a C18 (100 × 4.6mm; 2.6μ, Kinetex) column by isocratic elution. Detection wavelength was 241 nm. The degradation products were identified and characterized using UPLC-MS/TOF studies, and an attempt was made to isolate one of the degradation products by solvent extraction. The drug was found to significantly degrade under acidic/alkaline/neutral photolytic, oxidative, and alkaline hydrolytic conditions. Six degradation products (I-VI) were identified through LC-Q/TOF-MS studies that were adequately resolved from the drug with the developed UPLC method. All degradation products (I-VI) were ionized in the total ion chromatogram (TIC) in the LC-MS studies, and these were identified and characterized, and the degradation pathway of the drug was postulated. One of the oxidation products isolated from the degraded drug solution was characterized through differential scanning calorimetry, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance spectral data. Six degradation products generated from stress degradation studies on azelastine HCl were adequately resolved through LC-UV/PDA studies followed by method validation. These were successfully identified and characterized through LC-Q/TOF-MS studies, and the degradation pathways for the generation of these products from the drug have been postulated.

Two new coastal time-series of seawater carbonate system variables in the NW Mediterranean Sea: rates and mechanisms controlling pH changes

In this work, we present, for the first time, the seawater carbonate system measurements of two coastal time-series in the NW Mediterranean Sea, L’Estartit Oceanographic Station (EOS; 42.05°N 3.2542°E) and the Blanes Bay Microbial Observatory (BBMO; 41.665°N 2.805°E). At these two time-series, measurements of total alkalinity (TA), pH, and associated variables, such as dissolved inorganic nutrients, temperature, and salinity, have been performed monthly since 2010 in surface seawater. Seasonality and seasonal amplitude are analogous in both time-series, with seasonality in pHTin situ(pH at in situ seawater conditions on the total hydrogen ion scale) primarily determined by seasonality in sea surface temperature. The evaluated pHTin situtrends at BBMO (-0.0021 ± 0.0003 yr-1) and EOS (-0.0028 ± 0.0005 yr-1) agree with those reported for coastal and open ocean surface waters in the Mediterranean Sea and open ocean surface waters of the global ocean, therefore indicating that these time-series are representative of global ocean acidification signals despite being coastal. The decreases in pHTin situcan be attributed to increases in total dissolved inorganic carbon (DIC; 1.5 ± 0.4 µmol kg-1 yr-1 at BBMO and 1.6 ± 0.6 µmolESkg-1 yr-1 at EOS) and sea surface temperature (0.08 ± 0.02 °C yr-1 at BBMO and 0.08 ± 0.04 °C yr-1 at EOS). The increases in carbon dioxide fugacity (fCO2; 2.4 ± 0.3 µmol kg-1 yr-1 at BBMO and 2.9 ± 0.6 µmol kg-1 yr-1 at EOS) follow the atmospheric CO2 forcing, thus indicating the observed DIC increase is related to anthropogenic CO2 uptake. The increasing trends in TA (1.2 ± 0.3 µmol kg-1 yr-1 at BBMO and 1.0 ± 0.5 µmol kg-1 yr-1 at EOS) buffered the acidification rates, counteracting 60% and 72% of the pHTin situdecrease caused by increasing DIC at EOS and BBMO, respectively. Once accounted for the neutralizing effect of TA increase, the rapid sea surface warming plays a larger role in the observed pH decreases (43% at EOS and 62% at BBMO) than the DIC increase (36% at EOS and 33% at BBMO).

A pyrolysis‐gas chromatography/mass spectrometry study of volatile compounds produced by wood‐based materials

AbstractThe pyrolysis by‐products of five common wood‐based construction materials (low‐density wood fiberboard, oriented strand board, pine, particle board, and plywood) were studied using pyrolysis‐gas chromatography/mass spectrometry. Samples of wood‐based materials were pyrolyzed under helium from 300 to 800°C to further understand the production of compounds that may become airborne and available for respiratory and dermal exposure. Benzene, toluene, ethylbenzene, p‐xylene, styrene, and naphthalene were specifically targeted since these compounds are common by‐products of pyrolysis. These compounds have been measured in previous live fire scenarios and are associated with human health concerns. The generated pyrolysates were separated and identified with a gas chromatography/mass spectrometry instrument. The results from total ion chromatograms and selected ion monitoring chromatograms were analyzed to compare the abundance of chemicals of interest generated during pyrolysis. Oriented strand board and plywood generated the greatest total concentration of the targeted volatile organic compounds. Plywood and particle boards generated the largest variety in results. Samples from solid pine boards generated the smallest number of volatile compounds, followed by low‐density wood fiberboard that is manufactured with wood fibers, starch, and wax. Notably, pyrolysis by‐products are not the sole compounds generated during the combustion of biomass and these products evolve when they are exposed to the conditions of combustion. Our future work plans to study the combustion by‐products of these materials.

Contrasting patterns in pH variability in the Arabian Sea and Bay of Bengal.

Continuous understanding of the ongoing ocean acidification (OA) is essential for predicting the future impact of OA on marine ecosystems. Here we report the results of open ocean time-series measurements (19 cruises) of seawater pH in total hydrogen ion scale (pHT) and associated parameters in the Arabian Sea (AS) and the Bay of Bengal (BoB). During southwest monsoon (SWM), the pHT within the 30 to 100 m water column shows the maximum difference between the two basins with BoB pHT being lower (up to ~0.39 units) than AS which could be due to freshwater influx from rivers, mixed layer dynamics, and cold-core eddies. However, during Spring inter-monsoon (SIM), the pHT of BoB follows the trend of AS. A contrasting finding is that the lowest pHT occurs at 350 to 500 m in the BoB while it is ~1000 m in the AS. The pHT within the 150 to 1500 m layer of these two basins shows lower values by 0.03 (±0.02) in the BoB as compared to the AS. The possible reasons for the low pHT within the BoB oxygen minimum zone (OMZ) could be due to intrusion of western Pacific water in the BoB, freshwater influx from rivers, variations in OMZ of the two basins, higher temperature (~2°C) within the OMZ of the AS, anddenitrification in the AS. The pHT in both the basins (500 to 1000 m) is lower than in the North Atlantic and higher than in the North Pacific waters; however, the pHT in the 200 to 500 m is lower in the BoB than in all these basins. This study highlights the under-saturation of calcium carbonate at very shallow depths (~ 100 m) in the BoB, indicating that the plankton in the BoB are facing a major risk from OA compared to the AS and need further investigation.

Achieving Less Than 100 ppb Total Metal Ion Concentration in ESCAP Resins Synthesized by Atom Transfer Radical Polymerization

AbstractIn the photolithography process of integrated circuits （IC） manufacturing, it is desired that the photoresist resins have both smaller polydispersity index (PDI) and lower trace metal ion concentrations. The commercial environmentally stable chemical amplified photoresist (ESCAP) resins for 248 nm lithography are synthesized by free radical polymerization with PDI &gt;1.5. Although using atom transfer radical polymerization (ATRP) can result in lower PDI, the potential of high metal ion contamination is a major concern, as the reaction initiators usually are copper‐containing compounds. In this study, copolymer of p‐acetoxy styrene and tert‐butyl acrylate [poly(AOST‐co‐TBA)] is synthesized via ATRP achieving PDI as low as 1.25. It is then purified by ion exchange with two different resins, IRC747 and A15, which are effective at removing Cu and other metal ions. This reduces the total metal ion concentration in the copolymer powder to &lt;30 ppb with individual metal ion &lt;6 ppb. This is the first reported ATRP synthesized ESCAP resin having both low PDI and metal ion concentrations suitable for 248 nm photoresist application.

Geochemical Characteristics of Mesoproterozoic Source Rocks in North China: Insights for Organic Matter Enrichment and Thermal Evolution

In recent years, the exploration of oil and gas in China’s Precambrian strata has garnered significant attention, leading to notable advancements in exploration play assessment. However, there is a dearth of published literature on Proterozoic source rocks’ organic sources, sedimentary environments, marine hydrochemistry, and other attributes. This study focuses on investigating potential source rocks within the Hongshuizhuang and Xiamaling Formations in the Jibei Depression of North China. A comprehensive analysis was conducted to evaluate hydrocarbon generation characteristics, using hydrocarbon biomarkers and polar compounds as geochemical indicators for precursor biota and maturity levels. The results indicate high organic matter abundance with predominantly type I-II1 organic matter composition in the studied source rocks. These samples are at an immature–low mature stage, with the potential for primarily generating aromatic crude oil. The parent material is mainly attributed to lower aquatic organisms, such as bacteria and algae. The sedimentary environment exhibits marine facies, characterized by high evaporation rates, salinity levels, and strong euxinic conditions, that led to sulfur incorporation into the organic matter matrix. It should be noted that correlations between biomarker parameters and maturity may not be fully applicable to ancient source rocks; however, the methyldibenzothiophene ratio (MDR) demonstrates a strong correlation with Tmax. The compounds and their total monoisotope ions abundance (TMIA) were primarily identified and analyzed using FT–ICR MS. It was observed that these compounds were influenced by the depositional environment and organic matter maturity. Importantly, it was clearly demonstrated that the DBE and carbon number range of CH compounds gradually increased with maturity, due to the removal of N, S, and O functional groups. Specifically, N1 compounds predominantly consisted of carbazoles with short alkyl side chains which readily converted into N1Ox compounds. On the other hand, O1 compounds mainly comprised benzofurans with low abundance, indicating a reducing sedimentary environment, as suggested by their low TMIA values. Furthermore, S1 compounds were primarily thiophenes whose DBE range and carbon number increased with maturity, possibly suggesting an abiotic input of inorganic sulfur. Notably, the maturity indices (MAT) proved suitable for Mesoproterozoic source rocks while exhibiting strong linear relationships.