Chemical Measurements Research Articles

Degradation Analysis of Exciplex-Based Organic Light-Emitting Devices Using Carbazole-Based Materials.

A spectral shift and new emission bands in the green and red regions have been observed in deep blue exciplex-based organic light-emitting diodes (OLEDs) using carbazole-based materials, namely, tris(4-carbazoyl-9-ylphenyl)amine (TCTA). To deeply understand the origin of these new bands, single-layer and bilayer TCTA-based OLEDs subjected to electrical and optical (ultraviolet (UV)) stresses were investigated by using various optical, electrical, morphological, and chemical measurements. The results showed that the stress-induced emission bands primarily originate from morphological changes rather than chemical changes. The accumulation of excitons in the TCTA layer induces molecular aggregation, leading to the formation of electrically active electronic states, namely, electroplexes and electromers, which lead to the appearance of additional emission bands in green and red regions. Impedance spectroscopy measurements on single-layer OLEDs complemented this study. The results showed that TCTA degradation affects charge injection and transport. It was concluded that the stress-induced emission bands are caused by aggregate domain formation and are closely linked to the formation of electrically active defects, which act as trap states for charge carriers in the TCTA band gap.

Photothermal modulated hotspot for accurate and sensitive SERS detection of pesticides in complicated media

Designing smart surface-enhanced Raman scattering (SERS) nanosensors with superior sensibility, stabilities and repeatability is a challenging and intriguing goal in chemical measurement. Herein, we develop a photothermal modulated SERS platform (PM-SERS) for sensitive and stable analysis of targets by exploiting a stimuli-responsive gold nanoparticles (GNPs) decorated polyvinyl alcohol hydrogel (GPH). Importantly, the proposed GPH facilitates exactly controlling 3D hot-spot regions by modulating surrounding temperature and humidity. The adjustable GPH could not only act as a stable matrix for installing of high-density GNPs, but also as a sorption domain for preconcentration of targeted analyte in hot-spots sites, thus permitting simultaneously modulating 3D nanostructures and seizing targeted analytes in plasmonic regions. Crucially, because of the reversible nanostructures and nanoplasmonic features, GPH can eradicate adsorbates after being exposed to bromide solutions, thereby allowing renewable and reliable on-site SERS detection of complex media. The GPH-based PM-SERS platform exhibits excellent sensitivities and reproducibility for on-demand detection of multiplexed pesticide over a wide linear concentration range (2 × 10-6 to 103 μM), with detection limits as low as hundreds of fM. The GPH-based analytical platform provides tremendous potentials for credible quantification of complicated matrices and on-line process screening.

Identifying childhood pesticide exposure trajectories and critical window associated with behavioral problems at 10 years of age: Findings from SMBCS

BackgroundPesticides may impact children’s neurodevelopment. As children’s metabolic function and neural plasticity change throughout their growth and development, the effects of pesticide exposure may also vary. ObjectivesWe aimed to identify the trajectories of combined pesticide exposure during childhood, and examine the associations of the exposure trajectories with children’s neurobehavior at the age of 10. MethodsWe involved repeated measurements of three pesticide metabolites [Pentachlorophenol (PCP), 3,5,6-Trichloro-2-pyridinol (TCPy), and Carbofuran phenol (CFP)], in urine samples collected from children in a cohort study at ages 1, 2, 3, 6, 7, 8, 9, and 10 years. The group-based multi-trajectory model (GBMT) and latent class analysis (LCA) were separately utilized to describe the distinct trajectories and patterns of pesticide mixture exposure during childhood. Meanwhile, the Strengths and Difficulties Questionnaire (SDQ) and attention deficit hyperactivity disorder (ADHD) Criteria of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) list were applied to assess behavioral disorders in children. The associations between exposure trajectories and behavioral problem scores were then examined. ResultsThe GBMT model delineated three distinct trajectories of combined pesticide exposure among children: consistently low, higher levels in early childhood transitioning to lower levels during pre-school age, and lower levels in early childhood followed by higher levels in the middle childhood. The LCA model identified three similar longitudinal exposure patterns. Further, the children in the second trajectory group identified by GBMT, characterized by higher early childhood exposure levels, exhibited significantly elevated hyperactivity/inattention scores of the SDQ compared to the other two groups (β = 0.46, 95 %CI: 0.11, 0.81; β = 0.44, 95 %CI: 0.02, 0.86). ConclusionsOur study revealed that exposure to pesticides during early childhood (especially before the age of two), rather than other age periods, was linked to hyperactivity/inattention problems in children aged 10 years. We also provided a novel perspective on characterizing the fluctuation in repeated measurements of multiple environmental chemicals and identifying the potential critical windows.

Constructing HairDB to facilitate exposome research using human hair

This study introduces HairDB, an online database serving as a comprehensive repository of hair-related chemicals for exposome research. HairDB was created via an integrative approach. It first extracted 4,184 unique hair-related chemicals through text mining of over 34 million PubMed abstracts and 5.2 million PubMed Central articles, followed by manual data checking. HairDB also applied an artificial intelligence-enabled search to discover organic aerosol biomarkers in literature. A set of 768 chemicals used in hair-related products was then curated through a combination of manual searches and data extraction from the Cosmetic Ingredient Database (CosIng) of the European Union. From manually reading review papers, 29 organic aerosol biomarkers were extracted. Furthermore, 3,679 known exposure chemicals extracted from the Toxin and Toxin Target Database (T3DB) were incorporated in HairDB to represent the possible environmental exposures detected on hair surfaces. The comprehensive set of chemicals captured in HairDB represents the current knowledge of what can be found in and on hair. HairDB was constructed as a user-friendly web interface, allowing easy exploration of hair-related chemicals and tailored for annotating mass spectrometry-based hair exposomics data. The development of HairDB marks an important step forward in using hair as a biological matrix for chemical exposure measurement, facilitating the adoption of hair for exposome research. HairDB is publicly available at https://www.hairdb.ca/.

Seasonal and Climatic Drivers of Wet Deposition Organic Matter at the Continental Scale

AbstractDissolved organic matter (DOM) concentrations and composition within wet deposition are rarely monitored despite contributing a large input of bioavailable dissolved organic carbon (DOC) and nitrogen (DON) to the Earth's surface. Lacking from the literature are spatially comprehensive assessments of simultaneous measurements of wet deposition DOC and DON chemistry and their dependencies on metrics of climate and environmental factors. Here, we use archived precipitation samples from the US National Atmospheric Deposition Program collected in 2017 to 2018 from 17 sites across six ecoregions to investigate variability in the concentration and composition of depositional DOM. We hypothesize metrics of DOM chemistry vary with ecoregion, season, large‐scale climate drivers, and precipitation geographic source. Findings indicate differences in DOC and DON concentrations and loads among ecoregions. The highest wet deposition concentrations are from sites in the Northern Forests and lowest concentrations from sites in Marine West Coast Forests. Summer and autumn samples contained the highest DOC concentrations and DON concentrations that were consistently above detection limit, corresponding with seasonality of peak air temperatures and the phenology of the growing season in the northern hemisphere. Compositional trends suggest lighter DOM molecules in autumn and winter and heavier molecules in spring and summer. Climate drivers explain 51% of variation in DOM chemistry, revealing differing drivers on the concentrations and loads of DOC versus DON in wet deposition. This study highlights the necessity of incorporating DOC and DON measurements into national deposition monitoring networks to understand spatial and temporal feedbacks between climate change, atmospheric chemistry and landscape biogeochemistry.

Mining and urbanization affect river chemical water quality and macroinvertebrate communities in the upper Selenga River basin, Mongolia (revised version).

Mongolia is a country with a quickly growing economy mainly based on the mining of gold, copper, coal, and other minerals. Mining, urbanization, and agriculture impact the water quality in the upper Selenga River basin in northern Mongolia, which is the center of the Mongolian economy. Previous measurements of pollution loads were alarming, but restricted to chemical measurements. Here, for the first time, we combine freshwater biomonitoring and laboratory water quality data across a broad gradient of water quality and land use intensity. We track the effects of different types of pollution on aquatic invertebrates and test their use as bioindicators. We collected water samples, environmental parameters, and macroinvertebrates at 36 sampling sites at the rivers of Tuul, Kharaa, and Orkhon and their tributaries Sugnugur, Boroo, Sharyn Gol, Gatsuurt, and Yeröö. PCA of catchment water quality distinguished three groups of pollutants prevalent at the sites, (1) nutrients, (2) salt ions(Cl-, Na+, Mg2+, So42-, Ca2+) and mining by-products (B, Sr, U, Mo), and (3) (heavy) metals, which often exceeded regulatory standards. We recorded a total of 59 macroinvertebrate taxa belonging to 31 families in seven insect orders plus Amphipoda and Gastropoda. Species diversity declined with higher impact. Five environmental factors structured macroinvertebrate community composition in RDA: elevation of sample location, site total nitrogen, dissolved oxygen, electrical conductivity, and water chemistry. We conclude that macroinvertebrate communities are an appropriate and inexpensive tool for monitoring water quality in Mongolia and suggest government action to establish a long-term monitoring program.

SMCVdb: a database of experimental cellular toxicity information for drug candidate molecules.

Many drug discovery exercises fail because small molecules that are effective inhibitors of target proteins exhibit high cellular toxicity. Early and effective assessment of toxicity and pharmacokinetics is essential to accelerate the drug discovery process. Conventional methods for toxicity profiling, including in vitro and in vivo assays, are laborious and resource-intensive. In response, we introduce the Small Molecule Cell Viability Database (SMCVdb), a comprehensive resource containing toxicity data for over 24 000 compounds obtained through high-content imaging (HCI). SMCVdb seamlessly integrates chemical descriptions and molecular weight data, offering researchers a holistic platform for toxicity data aiding compound prioritization and selection based on biological and economic considerations. Data collection for SMCVdb involved a systematic approach combining HCI toxicity profiling with chemical information and quality control measures ensured data accuracy and consistency. The user-friendly web interface of SMCVdb provides multiple search and filter options, allowing users to query the database based on compound name, molecular weight range, or viability percentage. SMCVdb empowers users to access toxicity profiles, molecular weights, compound names, and chemical descriptions, facilitating the exploration of relationships between compound properties and their effects on cell viability. In summary, the database provides experimentally derived cellular toxicity information for over 24 000 drug candidate molecules to academic researchers, and pharmaceutical companies. The SMCVdb will keep growing and will prove to be a pivotal resource to expedite research in drug discovery and compound evaluation. Database URL: http://smcvdb.rcb.ac.in:4321/.

Relationship between root system-soil C:N:P and soil microbial diversity at different evolutionary stages of Caragana tibetica scrub in arid desert grassland, Northern China.

Scrub root systems play a crucial role in preventing soil erosion and nutrient loss. However, the effects of the root system configuration on soil nutrient dynamics and microbial changes at various evolutionary stages remain poorly understood. In this study, we investigated the relationship between soil physical and chemical properties and the diversity of bacteria and fungi throughout the evolutionary stages of the scrub root systems. This was achieved through a combination of whole-root excavation and root tracing techniques. The results indicated that root diameter was the main factor contributing to the continuous increase in carbon (C): phosphorus (P) and nitrogen (N): P ratios as the scrub sand pile developed. The soil organic carbon (SOC), total soil nitrogen (TN), and total soil phosphorus (TP) contents in the soil in the four evolutionary stages were the highest during the developmental stage, but the change in TP content was not statistically significant (P > 0.05). Partial least squares path modeling and redundancy analysis (RDA) indicated that root system stoichiometric C and N contents were positively correlated with microbial diversity (R2 = 0.85). There was no correlation between the evolutionary stage and soil nutrient TN, whereas soil nutrient TN was negatively correlated with microbial diversity (R2 = -0.92). These findings elucidate the relationship between the evolutionary stage of root chemical measurement characteristics, soil elements and microorganisms, and their subsequent effects on root elemental composition and microbial diversity. This study enhances the current understanding of plant-soil interactions in desert steppe ecosystems.

Introduction and Agrotechnology of Greek Chambala (Trigonella Foenum-Graecum L.) in Surkhondaryo Region

This research explores the introduction and agrotechnology of Greek Chambala (Trigonella foenum-graecum L.) in the Surkhandarya region of Uzbekistan. The study focuses on the growth development and medicinal properties of this leguminous herb, with particular emphasis on agrotechnological factors such as planting dates, row spacing, and chemical protection measures that influence productivity. Greek Chambala is valued for its bioactive compounds, known for medicinal benefits like managing diabetes and obesity. The experiment was conducted at the "Jonchekka Sarhadlari" farm using different planting configurations and fertilization methods. The results showed that planting in November yielded optimal seed development and contributed to soil fertility through nitrogen fixation. The findings provide practical insights for enhancing the cultivation of Greek Chambala in Surkhandarya's climatic conditions, making it a promising crop for both agricultural and medicinal purposes.

Characterization of the Major Elements and Paleoenvironmental Significance of the Shiyang Profile in the Weinan Basin, China

The enrichment and migration patterns of different chemical elements record paleoclimatic information in loess formations. The chemical elemental measurements of 245 samples from the Shiyang profile in the Weinan Region were compared with the geochemical characteristics of typical wind-formed profiles, and the paleoclimatic evolution was discussed. The results showed the following: (1) the standardized curves of the cumulative concentrations of SiO2, Al2O3, and CaO along with the Upper Continental Crust (UCC) in the Shiyang profile exhibited significant similarities with typical wind-formed profiles. This strongly suggests that the Shiyang profile has a wind-formed origin. (2) The mean value of the chemical index of alteration (CIA) of the Shiyang profile is 62.06, indicating that the Shiyang profile has been in the stage of primary chemical weathering. (3) The ratios of K2O/Al2O3, TiO2/Al2O3, and Fe2O3/Al2O3 in the Shiyang profile are comparable to those found in typical wind-formed profiles, suggesting a common source area and supporting the premise that the Shiyang profile is of wind-induced origin.(4) The regional climate has undergone a series of transitions: from a dry and cool phase in the early Holocene to warm and humid yet unstable conditions in the middle Holocene, and returning to dry and cool during the late Holocene.

Recent Advances in Luminophores for Enhanced Electrochemiluminescence Analysis.

Electrochemiluminescence (ECL) detection is widely applied in many fields, including chemical measurement, biological analysis, and clinic tests, due to its high sensitivity. Currently, the fast development of many new electrochemical luminophores is continuously improving the ECL-based detection ability. Besides the enhancement of luminescence emission for a high detection sensitivity, minimizing the effect of co-reactants on ECL detection and achieving multiple analysis in one sample are also the main directions in this field. This review focuses on a summary of recently prepared new luminophores to achieve the three aims mentioned above. Especially, the review is composed by three parts, focusing on the luminophores or materials with high ECL efficiency, self-enhancing properties, and multi-color ECL luminophores. The fabrication of biosensors using these molecules is also reviewed to exhibit the advances in biological applications.

Assessment of the impact of chemical security measures on domestic terrorism: a study of Boko Haram’s use of precursor chemicals in Nigeria

Assessment of the impact of chemical security measures on domestic terrorism: a study of Boko Haram’s use of precursor chemicals in Nigeria

Glassy Carbon Fiber‐Like Multielectrode Arrays for Neurochemical Sensing and Electrophysiology Recording

AbstractReal‐time measurement of neurochemical and electrophysiological activities in the living brain is vital for advancing neuroscience and understanding brain disorders. Carbon fiber microelectrodes (CFEs) have been widely utilized for in vivo electrochemical detection due to their subcellular size, biocompatibility, and desirable electrochemical properties, and CFE arrays have demonstrated excellent multi‐site chronic sensing of dopamine (DA) and neural activity recording capabilities. However, manual fabrication of CFE arrays lacks reproducibility and batch production capacity. Alternatively, photolithography enables batch fabrication of glassy carbon (GC) multielectrode arrays (GC‐MEAs) with high resolution and reproducibility, but the insertion of planar flexible MEAs poses challenges. In this study, GC fiber‐like (GCF) MEAs are presented and fabricated using photolithography. The GCF MEAs feature fiber‐like GC electrodes with small cross‐sections, facilitating self‐insertion into brain tissue without additional aids. Batch fabrication of GCF MEAs allows for customizable designs with minimal manual intervention. Comparative analysis with CFEs demonstrates improved electrochemical properties of GCF. In vivo experiments in mouse brains confirm the GCF MEAs' ability to measure neurotransmitter concentrations and record neural activities. This novel fabrication approach is promising for multimodal electrical and chemical measurements with minimal footprint, offering significant advancements in neural interface technology for neuroscience research and clinical applications.

Onboard multivariate hazard assessment for UIKKU chemical tanker by Gaidai reliability method

The current study outlines a novel multimodal structural reliability methodology, suitable for naval dynamic systems, that are either numerically simulated, or directly physically measured. Cross-correlations between the system's principal/key dimensions/components, along with the high dimensionality of complex naval dynamic systems, are not easily addressed by existing reliability methods, that are mostly univariate or bivariate. The objective of this study had been to apply a novel reliability/hazard assessment methodology to UIKKU chemical tanker onboard dynamic measurements to demonstrate the efficiency of the proposed multimodal structural reliability methodology. Current investigation utilized onboard measured ice loadings, exerted on the UIKKU tanker hull and propulsion devices during its Arctic voyage. Onboard dynamic data recordings then were interpreted to gain knowledge about dynamic load levels. The hull of UIKKU had been instrumented so that ice-induced loads/stresses on vessel shell plating had been monitored at various key locations, both in longitudinal as well as in vertical directions, along the vessel’s hull. Longitudinal bending stresses at several locations on the vessel hull and vessel vertical accelerations had been measured to analyze global vessel behaviour when colliding e.g., moderately heavy ice ridges. In addition to UIKKU onboard measurements onboard, Russian partners had instrumented icebreaker vessel Capitan Dranitsyn to real-time measure strains/stresses within ice belt grillage, located at the vessel’s bow. Icebreaker vessel Capitan Dranitsyn acted as escort icebreaker during the whole Arctic voyage. Obtained results may be utilized to harmonize IACS Polar ship rules. In the current study, the onboard measuring system along with measured results, during the whole voyage have been briefly represented.

Expressing the Unit of Measurement in Analytical Chemistry

Expressing the Unit of Measurement in Analytical Chemistry

Multi-diagnostic of dust growth in a capacitive Ar/C2H2 plasma

Abstract The interest in the production of nanoparticles (NPs) within Ar/C2H2 reactive plasmas is increasing, driven by their potential applications in functional materials or for their analogy to cosmic dust. The growth process of NPs has been thoroughly examined using a broad array of diagnostic tools. Significant among these tools are those that determine two-dimensional distributions of NP sizes and densities. The inherent complexity of these techniques has resulted in a limited number of works that integrate these measurements with a multitude of other diagnostic tools. Here, we show a multi-diagnostic exploration of the growing process of NPs in Ar/C2H2 plasmas. The combination of in-situ techniques, such as scattered light images, optical emission spectroscopy, light extinction, quadrupole mass signals, or self-bias voltage, with ex-situ scanning electron microscopy images and FTIR spectra of the deposited dust, provides a detailed picture of the growth process. The temporal evolution of plasma parameters, coupled with chemical composition measurements, provides a comprehensive description of the dust growth phases, and the FTIR measurements reveal an appreciable difference in chemical composition between the core and shell of the NPs. Furthermore, employing a method based on the terminal falling velocity of NPs in the afterglow, the intrinsic mass density of NPs is estimated. The asymmetries observed in the spatial distributions of NP size and density are qualitatively discussed in terms of neutral drag, ion drag, and electrostatic forces.

Chemical Quality (Water Content, Protein, Fiber) and Organoleptic Properties of Chicken Nuggets with Addition of Vegetables

This study aimed to assess the chemical quality (moisture content, protein, and fiber) and organoleptic properties of chicken nuggets with the addition of vegetables. The materials used included chicken breast, wheat flour, tapioca flour, bread crumbs, eggs, pepper, salt, ice water, carrots, broccoli, spinach, and young corn. Five treatments were applied: P0 (no vegetable addition), P1 (carrot addition), P2 (broccoli addition), P3 (spinach addition), and P4 (young corn addition). The research employed a Completely Randomized Design (CRD) for analyzing chemical quality and a Randomized Block Design (RBD) for examining organoleptic properties. Preferences were tested using the Kruskal-Wallis test. The chemical quality measurements included moisture content, protein, and crude fiber, while the organoleptic measurements assessed color, aroma, texture, taste, and preference. The results showed that the addition of vegetables significantly (P0.05) affected moisture content but had no significant effect (P0.05) on protein and fiber content. Furthermore, the addition of vegetables significantly (P0.05) influenced the color, aroma, and taste of the nuggets, but did not significantly affect (P0.05) texture and preference. It was concluded that incorporating 10% vegetables into chicken nuggets increased moisture content without affecting protein and fiber levels or overall preference. The addition of carrots yielded the highest scores for aroma and taste preference.

Metallicity calibrations based on auroral lines from PHANGS-MUSE data

We present a chemical analysis of selected regions from the PHANGS-MUSE nebular catalogue. Our intent is to empirically re-calibrate strong-line diagnostics of gas-phase metallicity, applicable across a wide range of metallicities within nearby star-forming galaxies. To ensure reliable measurements of auroral line fluxes, we carried out a new spectral fitting procedure whereby only restricted wavelength regions around the emission lines of interest are taken into account: this assures a better fit for the stellar continuum. No prior cuts to nebulae luminosity were applied to limit biases in auroral line detections. Ionic abundances of O$^+$ $, N$^+$, S$^+$, and S$^ $ were estimated by applying the direct method. We integrated the selected PHANGS-MUSE sample with other existing auroral line catalogues, appropriately re-analysed to obtain a homogeneous dataset. This was used to derive strong-line diagnostic calibrations that span from 12+log(O/H) = 7.5 to 8.8. We investigate their dependence on the ionisation parameter and conclude that it is likely the primary cause of the significant scatter observed in these diagnostics. We apply our newly calibrated strong-line diagnostics to the total sample of regions from the PHANGS-MUSE nebular catalogue, and we exploit these indirect metallicity estimates to study the radial metallicity gradient within each of the 19 galaxies of the sample. We compare our results with the literature and find good agreement, validating our procedure and findings. With this paper, we release the full catalogue of auroral and nebular line fluxes for the selected regions from the PHANGS-MUSE nebular catalogue. This is the first catalogue of direct chemical abundance measurements carried out with PHANGS-MUSE data.

Identifying the sex chromosome and sex determination genes in the cattle tick, Rhipicephalus (Boophilus) microplus.

Rhipicephalus (Boophilus) microplus is globally one of the most economically important ectoparasites of cattle costing the agriculture industry billions of dollars annually. Resistance to chemical control measures has prompted the development of novel methods of control. Recent advancements in genetic control measures for human and other animal vectors have utilized sex determination research to manipulate sex ratios, which have shown promising results in mosquitoes namely Aedes aegypti and Anopheles stephensi. Here, we use R. (B.) microplus as a model to provide foundational research to allow similar avenues of investigation in ticks using R. (B.) microplus as a model. Karyotypes for R. (B.) microplus show an XX:XO sex determining system with the largest chromosome being the sex chromosome. Using flow cytometric methods, the size of the sex chromosome was estimated at 526.91 Mb. All measures to identify the sex chromosome within the cattle tick genome assembly associated sex chromosomal characteristics to two chromosomes. This discrepancy between the assembly and karyotypes of the tick led to generating a new genome assembly with a single adult male specimen. The two chromosomes in question aligned with a single scaffold within the new genome that had a length of 513.29 Mb and was the first time the sex chromosome was identified in an Ixodid genome assembly.

Mitigating inland waters’ greenhouse gas emissions: current insights and prospects

ABSTRACT Natural and constructed inland waters emit globally significant amounts of greenhouse gasses (GHGs) into the atmosphere. As a result of human-induced alterations in the landscape, these emissions tend to increase. While proper management of waterbodies is fundamental to reaching the global sustainable development goals as well as the Paris Agreement, insights on climate-smart inland water management are still underexplored. Here we review and discuss physical, chemical, and biological management measures applied in a wide range of inland waters to (1) reduce external loads of compounds fueling aquatic GHG emissions, (2) reduce the aquatic production of GHG-fueling compounds, and (3) minimize GHG production and stimulate GHG consumption. Some measures are well studied and others are in the exploration phase, resulting in a varying degree of confidence with respect to their effectiveness. Climate-smart water management (e.g., through the reduction of organic matter and nutrient loading) generally not only reduces GHG production and emission but also improves the ecological state of aquatic environments. Reductions in GHG emissions from 5% (fish effect) to ∼90% (salinization effect) were observed among the climate-smart measures discussed here. Certainly, the global effect of the different measures also depends on the application scale. Depending on the local context, the implementation of one or more of these measures can be considered in a GHG mitigation program.