Precursor Compounds Research Articles

Anthropogenic and Biogenic Sources Drive the Molecular Fingerprints and Atmospheric Processing of Water‐Soluble Organic Aerosols at a Tropical Hill Station in the Western Ghats of India

AbstractThe widespread presence of organic aerosols (OA) in the atmosphere and their dominant role in climate forcing are increasingly recognized. Measurements from the high‐altitude region provide insights into the natural processes and long‐range transport of aerosols. We studied water‐soluble organic compounds in PM1.1 during January‐March 2020 and February‐April 2021 at Ponmudi (8.8°N and 77.1°E), a tropical hill station (960 m a.s.l.) located on the Western Ghats of India. The 5‐day backward trajectories of air masses presented that continental and marine sources impacted the site during the campaign, and thus we classified samples as mixed and marine air masses. Their molecular fingerprints revealed the prevalence of oxalic acid (C2), followed by terephthalic acid in mixed air mass and malonic (C3) or succinic (C4) acid in maritime air mass aerosol samples. This feature and the phthalic to azelaic acid ratio, as well as the C3 to C4 and fumaric to maleic acid ratios, evidenced that water‐soluble OA were of anthropogenic origin and less photochemically aged in mixed air mass samples, whereas they derived from biogenic sources and more photochemical aging in marine air mass samples. However, we found their comparable contributions in water‐soluble organic carbon under mixed and marine air masses. Linear correlations between C2 relative abundance and its ratios with the precursor compounds implied that the oxidation of precursors to oxalic acid occurs during atmospheric transport. The results revealed that the input of anthropogenic and biogenic precursors followed by atmospheric processing controlled the burden of water‐soluble OA across the Western Ghats.

Respon Pertumbuhan Bibit Bud Set Tebu (Saccarum officinarum L.) Pada Aplikasi Mikroorganisme Lokal Dari Fermentasi Ekstrak Keong Emas

Sugarcane plant (Saccarum officinarum L.) is one of the plantation commodities as a raw material for sugar production. The success rate of sugar production is greatly influenced by productivity, one of which is nursery techniques and soil nutrient requirements. In the nursery aspect, the innovation of the single bud planting (SBP) or Bud set method of sugarcane seeding is currently the recommended technology for sugarcane nurseries. The advantages of the Bud set include simultaneous growth, no need for large areas of land, early maturing seeds, and high quality and certainty of life. But for alternative fertilizers that currently can use organic fertilizers from materials around. One of them is a biological organic fertilizer containing Local Microorganisms (MOL) made from golden snail, where the tryptophan amino acid compound is the precursor compound for ZPT Indole Acetic Acid (IAA) so that it can be used as a growth regulator. The golden snail MOL treatment used a concentration of 0% (control); 2.5%; 5.0%; 7.5%; 10.0%; 12.5% ​​with an application frequency of 2 weeks and 4 weeks on 180 sugarcane seeds. The aim of the study was to examine the use of liquid organic fertilizer from golden snail on the productivity of sugarcane. The best results of the study and the parameters used occurred in the 8th week, namely, stem diameter 1.09 cm, number of tillers 3,6, root wet weight 18,23 grams, root dry weight 6,33 grams, and root length 32,33 cm

Impact of Precursor Compounds Associated with Long-Range Transport in the East Asia Region—Variation in CO/CO2 and VOCs

In this study, the impact of long-range transport, one of the factors contributing to the presence of PM2.5, was examined, and an analysis of marker compounds associated with its long-range transport was conducted. Aerosol optical depth, wind field, CO/CO2 back-trajectory analysis, and satellite observation results were performed to determine PM2.5, volatile organic compound (VOC), CO, CO2, SO2, O3, NO, NO2, and NH3 levels at an orchard located in Jeollabuk-do, Republic of Korea. The characteristic of long-range transport at the observation area was evaluated during the research period. The concentrations for long-range transport based on concentration changes in gaseous materials and composition changes in PM2.5 were analyzed. A back-trajectory analysis for the ratio of CO to CO2 with satellite observation results was used to identify long-range transport. Furthermore, the proportionality between the ratio of 1,2-dichloroethane to naphthalene in VOCs and the quantity of precursor compounds linked to long-range transport were observed.

Evolution of Markers Involved in the Fresh Mushroom Off-Flavor in Wine During Alcoholic Fermentation.

The fresh mushroom off-flavor (FMOff) is due to several C8 compounds such as 1-octen-3-one, 1-octen-3-ol and 1-hydroxyoctan-3-one, among others. Recently, glycosidic precursors of some FMOff compounds have been identified in grape musts, but the evolution of such compounds during alcoholic fermentation (AF) remains poorly studied. Therefore, the aim of this work was to monitor both FMOff glycosidic precursors and volatile compounds during AF by comparing healthy and Crustomyces subabruptus-contaminated musts. For the first time, glycosidic analysis revealed the presence of 1-hydroxyoctan-3-one glycosides in the laboratory-contaminated musts, together with other FMOff glycosidic fractions already described in the literature. During AF, the FMOff glycosidic fraction decreased, even more in the case of 1-hydroxyoctan-3-one precursors. For the volatile FMOff compounds, their evolutions were both compound- and matrix-dependent except for 1-hydroxyoctan-3-one, which seemed to reach an identical threshold concentration in wine regardless of its initial level in contaminated musts.

A comparative study of lupeol extraction from a by‐product of lupin processing by hydrophobic natural deep eutectic solvents and their precursor components

AbstractA series of hydrophobic natural deep eutectic solvents (HNADESs) have been employed to extract lupeol from lupin seed coat at 30 and 70°C. The extraction yields have been compared with those obtained with conventional organic solvents. In general, lupeol extraction yields (LEYs) obtained when using HNADES are somewhat smaller than those obtained if organic solvents are used. However, the nature of the HNADES mixtures as green solvents represents a superior performance in terms of sustainability of the extraction process. Additionally, an investigation has been carried out in order to compare the LEYs obtained when using the HNADES mixtures with those obtained if the isolated precursor compounds are employed at a temperature (70°C) where both HNADES and the corresponding precursor compounds are liquids. Surprisingly, LEYs for lupeol at 70°C were found to be, in some cases, slightly higher if the precursor compounds are used in comparison with the proper HNADES mixtures. It seems that the unique properties of the HNADES mixtures are not enough to perform better as extractants in comparison with the isolated precursor compounds at moderate temperatures, at least for the case of lupeol from lupin seed coat. Some hints are presented to explain these results.Practical Applications: The demand to use by‐products, such as raw materials, to obtain potential bioactive compounds is gaining strong attention in the last years. The use of green solvents to extract these compounds is also envisaged to obtain substances in an environment‐friendly way and with high sustainability for the economy and end‐consumers. The main aim of this work is the extraction of lupeol from lupin seed coat by using on one side different hydrophobic natural deep eutectic solvent (HNADES) mixtures, and on the other side by using the precursor compounds of the mixtures, in order to evaluate the efficiency of these green extraction solvents in the recovery of bioactive compounds with health benefits from waste material. Our results show that lupeol can be extracted both with the HNADES mixtures and with their precursor components at moderate temperatures with similar efficiency. This work questions the need of using HNADES as clean extraction solvents as the precursor compounds have themselves interesting extracting capacities.

One-pot nucleophilic substitution-double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives.

The nucleophilic substitution of benzylic bromides with sodium azide was combined with a subsequent copper-catalyzed (3 + 2) cycloaddition with terminal alkynes. This one-pot process was developed with a simple model alkyne, but then applied to more complex alkynes bearing enantiopure 1,2-oxazinyl substituents. Hence, the precursor compounds 1,2-, 1,3- or 1,4-bis(bromomethyl)benzene furnished geometrically differing bis(1,2,3-triazole) derivatives. The use of tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) as ligand for the click step turned out to be very advantageous. The compounds with 1,2-oxazinyl end groups can potentially serve as precursors of divalent carbohydrate mimetics, but the reductive cleavage of the 1,2-oxazine rings to aminopyran moieties did not proceed cleanly with these compounds.

Synthesis and characterization of energetic molecules based on pyrimidine rings: Selection and verification of computational-assisted synthesis pathways

The current rise in performance prediction techniques for energetic compounds provides the possibility of prejudging the effectiveness of derived patterns. In this work, 2,4-diamino-6-chloropyrimidine was used as the precursor, and the three possible derived pathways were systematically explored (guest oxidant, nitration, and N-oxidation). Theoretical calculations were adopted to predict the energy and stability parameters of possible products. The calculations indicated that constructing bridged-ring energetic molecules with N-oxide and nitro group is an effective way to balance energy and safety. Based on this protocol, we synthesized a series of pyrimidine-based energetic molecules within three steps and tested and analyzed their physicochemical properties, verifying the consistency between experimental results and theoretical predictions. This work provides a research model for determining the feasibility and effectiveness of the derivative pathway based on a specific energetic compound precursor and can offer guidance for the directed and large-scale synthesis of high-energy and low-sensitivity explosive molecules.

Thermally-Induced Isomerization of Prenucleation Clusters During the Prenucleation Stage of CdTe Quantum Dots.

The evolution of prenucleation clusters in the prenucleation stage of colloidal semiconductor quantum dots (QDs) has remained unexplored. With CdTe as a model system, we show that substances form and isomerize prior to the nucleation and growth of QDs. Called precursor compounds (PCs), the prenucleation clusters are relatively optically transparent and can transform to absorbing magic-size clusters (MSCs). When a prenucleation-stage sample at 25, 45, or 80 °C is dispersed in a mixture of cyclohexane (CH) and octylamine (OTA) at room temperature, either MSC-371, MSC-417, or MSC-448 evolves with absorption peaking at 371, 417, or 448 nm, respectively. We propose that PC-371 forms at 25 °C, and isomerizes to PC-417 at 45 °C and to PC-448 at 80 °C. The PCs and MSCs are quasi isomers. Relatively large and small amounts of OTA favor PC-371 and PC-448 in dispersion, respectively. The present findings suggest the existence of PC-to-PC isomerization in the QD prenucleation stage.

Thermally‐Induced Isomerization of Prenucleation Clusters During the Prenucleation Stage of CdTe Quantum Dots

AbstractThe evolution of prenucleation clusters in the prenucleation stage of colloidal semiconductor quantum dots (QDs) has remained unexplored. With CdTe as a model system, we show that substances form and isomerize prior to the nucleation and growth of QDs. Called precursor compounds (PCs), the prenucleation clusters are relatively optically transparent and can transform to absorbing magic‐size clusters (MSCs). When a prenucleation‐stage sample at 25, 45, or 80 °C is dispersed in a mixture of cyclohexane (CH) and octylamine (OTA) at room temperature, either MSC‐371, MSC‐417, or MSC‐448 evolves with absorption peaking at 371, 417, or 448 nm, respectively. We propose that PC‐371 forms at 25 °C, and isomerizes to PC‐417 at 45 °C and to PC‐448 at 80 °C. The PCs and MSCs are quasi isomers. Relatively large and small amounts of OTA favor PC‐371 and PC‐448 in dispersion, respectively. The present findings suggest the existence of PC‐to‐PC isomerization in the QD prenucleation stage.

Controlled preparation of Gd2O2SO4:Eu3+ monospheres via hydrothermal precursor engineering for enhanced photoluminescence

Rare-earth oxysulfates (RE2O2SO4) attracted attention for large-capacity oxygen storage, low-temperature magnetism and luminescence, whose preparation mostly involves toxic SOx gases and/or complicated procedures. In the phosphor field, monospheres are preferred for a number of applications due to their better luminescence and high packing density. With the simple reactants of RE(NO3)3, Na2CO3 and (NH4)2SO4 for hydrothermal reaction, dispersed monospheres and nanoplates were selectively synthesized for the recently discovered RE2(OH)2CO3SO4·nH2O (RE = Gd0.95Eu0.05, REOCSH) layered compound precursor, from which RE2O2SO4 phosphors mostly retaining their precursor morphologies were facilely derived via calcination in air at 800 °C, without involving SOx. Solution pH was found to decisively determine the chemical composition and crystallization kinetics of the initial precipitate, and the possible mechanisms of phase/morphology evolution during hydrothermal treatment were proposed by comparatively investigating the temperature-course and time-course of REOCSH formation under the typical pH values of 6 and 7. It was revealed that (Gd0.95Eu0.05)2O2SO4 monospheres emit ∼1.35 times as strong as nanoplates (λex = 257 nm, λem = 617 nm) and may retain as high as ∼81% of the room-temperature intensity at 150 °C. The phosphor monospheres were also analyzed to have a fluorescence lifetime of ∼1.32 ms at room temperature and an activation energy of ∼0.19 eV for the thermal quenching of luminescence.

Scaling up of native species for a sustainable microalgal biorefinery targeting different microalgal products

The present study aims to establish a sustainable bio refinery production in a semi-outdoor environment using two different types of media; fertilizer-based medium (FBM) and wastewater based medium (WWBM). A comparative study was performed under laboratory conditions to evaluate the effects of these media on a smaller scale. Cultivation was further scaled up to 500 L volume using WWBM resulting in four folds more biomass accumulation, 1.3 folds more carbohydrate accumulation, and 1.2 folds more lipids compared to cultivation under laboratory conditions. In this study, the species Ettlia texensis was used. It was isolated from the nearby regions of Indore. Being indigenous, Ettlia texensis easily adapted to Indore's climatic conditions and produced important precursors without compromising biomass. With the supplementation of WWBM at 500 L cultivation volume, E. texensis was able to produce 493.4 ± 34.4 μg of lipid per mg of biomass, which was 1.5 folds higher than at the laboratory scale. This study facilitates successful up-scaling of the process by providing insight into the utilization of low-cost media for microalgal production. The semi-outdoor cultivation of E. texensis to produce precursors of various compounds is used in this study for the first time.

Temperature and soil moisture change microbial allocation of pesticide‐derived carbon

AbstractTemperature and soil moisture are known to control pesticide mineralization. Half‐life times () derived from pesticide mineralization curves generally indicate longer residence times at low soil temperature and moisture but do not consider potential changes in the microbial allocation of pesticide‐derived carbon (C). We aimed to determine carbon use efficiency (, formation of new biomass relative to total C uptake) to better understand microbial utilization of pesticide‐derived C under different environmental conditions and to support the conventional description of degradation dynamics based on mineralization. We performed a microcosm experiment at two MCPA (2‐methyl‐4‐chlorophenoxyacetic acid) concentrations (1 and 20 mg kg−1) and defined 20°C/pF 1.8 as optimal and 10°C/pF 3.5 as limiting environmental conditions. After 4 weeks, 70% of the initially applied MCPA was mineralized under optimal conditions but MCPA mineralization reached less than 25% under limiting conditions. However, under limiting conditions, an increase in was observed, indicating a shift towards anabolic utilization of MCPA‐derived C. In this case, increased C assimilation implied C storage or the formation of precursor compounds to support resistance mechanisms, rather than actual growth since we did not find an increase in the tfdA gene relevant to MCPA degradation. We were able to confirm the assumption that under limiting conditions, C assimilation increases relative to mineralization and that C redistribution, may serve as an explanation for the difference between mineralization and MCPA dissipation‐derived degradation dynamics. In addition, by introducing to the temperature‐ and moisture‐dependent degradation of pesticides, we can capture the underlying microbial constraints and adaptive mechanisms to changing environmental conditions.

Valorization of Naturally Abundant Low-Value Peat into Highly Active Non-Platinum Group Metal Oxygen Reduction Catalysts

As society continues to adopt an increasingly eco-friendly stance, the efficient usage of natural resources needs to be maximised. For instance, energy obtained from biomass covers roughly a tenth of the global demand. This biomass can instead be used as a carbon source to produce value-added materials such as tnon-platinum group metal (NPGM) oxygen reduction catalysts, which are desperately sought after as global demand for fuel cells continues to rise [1,2]. For example, peat is an extremely abundant biomass material in Estonia covering roughly 20% of the country [3]. Herein, the viability of using peat-based catalysts as oxygen reduction catalysts in alkaline media was investigated.The peat sourced from a local peatland was processed and modified with inexpensive iron and nitrogen precursors through the common double-pyrolysis and acid washing synthesis procedure into peat-based NPGM catalysts. Additionally, zinc chloride was used as a pore forming agent. The influence of several principal synthesis parameters, e.g. precursor compound type and amount, on the physical and electrochemical properties of these materials was investigated using various characterization methods.The NPGM catalysts obtained from naturally abundant peat were highly microporous systems due to the inclusion of zinc chloride in the synthesis mixture. High onset (~0.93 V vs RHE) and half-wave potential (~0.83 V vs RHE) values were obtained for most of the materials in activity screening experiments conducted with a rotating disc electrode setup using 0.1 M KOH. However, using an excessive amount of the nitrogen precursor in the synthesis proved to be detrimental to the obtained activity. The high activity of the obtained peat-derived catalysts was further investigated in a rotating ring disc electrode setup where the influence of the studied synthesis parameters on the oxygen reduction reaction selectivity was more evident. Acknowledgments This work was supported by the EU through the European Regional Development Fund under projects TK141 “Advanced materials and high-technology devices for energy recuperation systems” (2014-2020.4.01.15-0011), NAMUR “Nanomaterials - research and applications” (3.2.0304.12-0397), NAMUR+ core facility funded by the Estonian Research Council (TT 13), PRG676 “Development of express analysis methods for micro-mesoporous materials for Estonian peat derived carbon supercapacitors” (01.01.2020–31.12.2024) and PUT1581 (1.01.2017–31.12.2020). References F. Jaouen, D. Jones, N. Coutard, V. Artero, P. Strasser, A. Kucernak, Johns. Matthey Technol Rev. 2018, 62, 231. E4tech, 2022, The Fuel Cell Industry Review 2021. M. Orru, H. Orru, Est. J. Earth Sci. 2008, 57, 87.

Panchromatic Light-Capturing Bis-styryl BODIPY-Perylenediimide Donor-Acceptor Constructs: Occurrence of Sequential Energy Transfer Followed by Electron Transfer.

Two wide-band-capturing donor-acceptor conjugates featuring bis-styrylBODIPY and perylenediimide (PDI) have been newly synthesized, and the occurrence of ultrafast excitation transfer from the 1 PDI* to BODIPY, and a subsequent electron transfer from the 1 BODIPY* to PDI have been demonstrated. Optical absorption studies revealed panchromatic light capture but offered no evidence of ground-state interactions between the donor and acceptor entities. Steady-state fluorescence and excitation spectral recordings provided evidence of singlet-singlet energy transfer in these dyads, and quenched fluorescence of bis-styrylBODIPY emission in the dyads suggested additional photo-events. The facile oxidation of bis-styrylBODIPY and facile reduction of PDI, establishing their relative roles of electron donor and acceptor, were borne out by electrochemical studies. The electrostatic potential surfaces of the S1 and S2 states, derived from time-dependent DFT calculations, supported excited charge transfer in these dyads. Spectro-electrochemical studies on one-electron-oxidized and one-electron-reduced dyads and the monomeric precursor compounds were also performed in a thin-layer optical cell under corresponding applied potentials. From this study, both bis-styrylBODIPY⋅+ and PDI⋅- could be spectrally characterizes and were subsequently used in characterizing the electron-transfer products. Finally, pump-probe spectral studies were performed in dichlorobenzene under selective PDI and bis-styrylBODIPY excitation to secure energy and electron-transfer evidence. The measured rate constants for energy transfer, kENT , were in the range of 1011 s-1 , while the electron transfer rate constants, kET , were in the range of 1010 s-1 , thus highlighting their potential use in solar energy harvesting and optoelectronic applications.

Long Chain Polyunsaturated Fatty Acids and Their Role in COVID 19-associated Inflammation and Dysbiosis

The COVID-19 pandemic has been an on-going global health problem since it started more than three years ago. Efficient treatment and its emerging long-term effects remain unresolved. The primary cause of COVID-19 deaths is the excessive immune response resulting in a cytokine storm leading to eventual organ failure. Dysbiosis has been observed in patients infected with SARS-CoV-2, promoting further inflammation and increasing risks for long COVID. Most of the current treatments for COVID-19 including vaccines are directed against the virus and its replication. However, these treatments need to be administered before viral infection (in the case of vaccines) or early in the infection process. Moreover, these treatments do not address the inflammatory phase of the disease, where cytokine storm increases the risk of death or may be a significant contributor to long COVID. Omega-3 fatty acids which are components of cell membranes are known to be precursors of anti-inflammatory compounds and aid in the regulation of the human microbiome. This article presents a hypothesis that posits the role of long-chain polyunsaturated fatty acids in modulating COVID-19 inflammation via the regulation of the lung and gut microbiomes, which have been associated with the body's immune response to SARS-CoV-2 infection. With known safety and benefits of omega-3 fatty acids, supplementation may be effective in preventing severe COVID-19 symptoms, managing mild and moderate symptoms, and may even extend post-recovery to mitigate increased risk for cardiovascular diseases after SARS-CoV-2 infection and recovery.

Fluorine mass balance analysis of PFAS in communal waters at a wastewater plant from Austria

Wastewater treatment plants are a major source of per and polyfluoroalkyl substances (PFAS) in the environment; moreover, long chain PFAS are known to accumulate in sewage sludge. Although publications on PFAS in wastewater are available from around the globe, little information is available from Central Europe. In this study influent, effluent, and sludge from two wastewater treatment plants from Austria were analysed for target PFAS compounds with HPLC MS/MS and extractable organic fluorine (EOF) content with combustion ion chromatography (CIC). The sum of 31 target PFAS increased from 22 to 47 ng L–1 in influent to 140 – 213 ng L–1 in effluent and around 10 ng g–1 in sludge, while EOF were found to be consistent (2.3 – 3.5 µg F L–1) in influent/effluent and 280 ng F g–1 in sludge. Mass balance analysis showed an increase in the identified PFAS compounds in the effluent compared to the influent (from 0.9% - 1.3% to 3.6% - 6.1%), suggesting biotransformation of non-targeted PFAS precursor compounds. In conclusion, wastewater treatment plants transform some PFAS, and wastewater effluent is a source of PFAS contamination in surface water.

Methane accumulation and its potential precursor compounds in the oxic surface water layer of two contrasting stratified lakes

Methane (CH4) supersaturation in oxygenated waters is a widespread phenomenon despite the traditional perception of strict anoxic methanogenesis. This notion has recently been challenged by successive findings of processes and mechanisms that produce CH4 in oxic environments. While some of the processes contributing to the vertical accumulation of CH4 in the oxygenated upper water layers of freshwater lakes have been identified, temporal variations as well as drivers are still poorly understood. In this study, we investigated the accumulation of CH4 in oxic water layers of two contrasting lakes in Germany: Lake Willersinnweiher (shallow, monomictic, eutrophic) and Lake Stechlin (deep, dimictic, eutrophic) from 2019 to 2020. The dynamics of isotopic values of CH4 and the role of potential precursor compounds of oxic CH4 production were explored. During the study period, persistent strong CH4 supersaturation (relative to air) was observed in the surface waters, mostly concentrated around the thermocline. The magnitude of vertical CH4 accumulation strongly varied over season and was generally more pronounced in shallow Lake Willersinnweiher. In both lakes, increases in CH4 concentrations from the surface to the thermocline mostly coincided with an enrichment in 13C-CH4 and 2H-CH4, indicating a complex interaction of multiple processes such as CH4 oxidation, CH4 transport from littoral sediments and oxic CH4 production, sustaining and controlling this CH4 supersaturation. Furthermore, incubation experiments with 13C- and 2H-labelled methylated P-, N- and C- compounds clearly showed that methylphosphonate, methylamine and methionine acted as potent precursors of accumulating CH4 and at least partly sustained CH4 supersaturation. This highlights the need to better understand the mechanisms underlying CH4 accumulation by focusing on production and transport pathways of CH4 and its precursor compounds, e.g., produced via phytoplankton. Such knowledge forms the foundation to better predict aquatic CH4 dynamics and its subsequent rates of emission to the atmosphere.

A new aggregation-induced emission-based fluorescent probe for effective detection of Hg2+ in water, tea and seafood and its cell imaging

Mercury ion (Hg2+) is highly toxic to the environment and organisms, therefore, monitoring and quantitative detection of Hg2+ is of great significance. In this work, a new fluorescent probe TPEH that integrated tetraphenylethene (TPE) and 2-(2′-hydroxyphenyl)benzothiazole was designed and synthesised. In EtOH/HEPES (2:8, v/v, pH = 7.2) solution, TPEH displays fluorescence turn on detection of Hg2+ with the advantages of swift response (<100 s), high selectivity and strong disturbance-resistant, a large Stokes shift (220 nm), and low limit of detection (81.7 nM). The sensing mechanism was proved to be Hg2+-triggered releasing of the aggregation-induced emission (AIE)-active precursor compound 2. TPEH has been successfully applied to detect Hg2+ in seafood and tea, and image Hg2+ in living cells. In addition, TPEH can be used to detect the content of Hg2+ in actual water samples with the aid of smartphone.

Amino Acid Catabolism: An Overlooked Area of Metabolism.

Amino acids have been extensively studied in nutrition, mainly as key elements for maintaining optimal protein synthesis in the body as well as precursors of various nitrogen-containing compounds. However, it is now known that amino acid catabolism is an important element for the metabolic control of different biological processes, although it is still a developing field to have a deeper understanding of its biological implications. The mechanisms involved in the regulation of amino acid catabolism now include the contribution of the gut microbiota to amino acid oxidation and metabolite generation in the intestine, the molecular mechanisms of transcriptional control, and the participation of specific miRNAs involved in the regulation of amino acid degrading enzymes. In addition, molecules derived from amino acid catabolism play a role in metabolism as they are used in the epigenetic regulation of many genes. Thus, this review aims to examine the mechanisms of amino acid catabolism and to support the idea that this process is associated with the immune response, abnormalities during obesity, in particular insulin resistance, and the regulation of thermogenesis.

Using the POD sampler for quantitative diffusive (passive) monitoring of volatile and very volatile organics in ambient air: Sampling rates and analytical performance

POD diffusive samplers loaded with Carbopack X and Carbograph 5TD were exposed to certified calibration mixtures containing a total of 110 different ozone precursor and air toxic compounds. Constant sampling rates were identified for 39 ozone precursors and 33 air toxics. As 9 of these compounds were included in both mixtures, this meant a total of 63 different volatile and very volatile compounds were sampled using the POD with overall expanded uncertainties below 30 % for the sampling rate associated with the whole range of sampling times from 2 to 24 h.Carbograph 5TD exhibited superior performance for diffusive sampling of oxygenated and halogenated compounds in the air toxics mixture, while Carbopack X showed higher sampling efficiencies for aliphatic and aromatic hydrocarbons, as well as halogenated compounds derived from benzene and C2 carbon number hydrocarbons.A model has been developed and applied to estimate sampling rates, primarily for the more volatile and weakly adsorbed compounds, as a function of the collected amount of analyte and the exposure time. For an additional 9 ozone precursors on Carbopack X, and 11 air toxics on Carbograph 5TD, the expanded uncertainties of modelled sampling rates were reduced to below 30 % and have a significantly reduced uncertainty compared to those associated with an averaged sampling rate.The paper provides Freundlich’s isotherm parameters for the estimated (modelled) sampling rates and defines a pragmatic approach to their application. It does so by identifying the best sampling time to use for the expected exposure concentrations and associated analyte masses. This allows for expansion of the sampling concentration range from hundreds ng m−3 to mg m−3, while avoiding saturation of the adsorbent.Finally, field measurement comparisons of POD samplers, pumped tube samplers and online gas chromatography (GC), for sampling periods of 3 and 7 days in a semi-rural background area, showed no significant differences between reported concentrations.