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1.
J Med Chem ; 67(16): 13639-13665, 2024 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-39096294

RESUMEN

Inositol hexakisphosphate kinases (IP6Ks) have been studied for their role in glucose homeostasis, metabolic disease, fatty liver disease, chronic kidney disease, neurological development, and psychiatric disease. IP6Ks phosphorylate inositol hexakisphosphate (IP6) to the pyrophosphate, 5-diphosphoinositol-1,2,3,4,6-pentakisphosphate (5-IP7). Most of the currently known potent IP6K inhibitors contain a critical carboxylic acid which limits blood-brain barrier (BBB) penetration. In this work, the synthesis and testing of a variety of carboxylic acid isosteres resulted in several new compounds with improved BBB penetration. The most promising compound has an IP6K1 IC50 of 16 nM with an improved brain/plasma ratio and a favorable pharmacokinetic profile. This series of brain penetrant compounds may be used to investigate the role of IP6Ks in CNS disorders.


Asunto(s)
Barrera Hematoencefálica , Fosfotransferasas (Aceptor del Grupo Fosfato) , Barrera Hematoencefálica/metabolismo , Fosfotransferasas (Aceptor del Grupo Fosfato)/metabolismo , Fosfotransferasas (Aceptor del Grupo Fosfato)/antagonistas & inhibidores , Animales , Humanos , Relación Estructura-Actividad , Inhibidores Enzimáticos/farmacología , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Ratones , Masculino , Ácidos Carboxílicos/química , Ácidos Carboxílicos/farmacología , Ácidos Carboxílicos/síntesis química , Ratas
2.
bioRxiv ; 2024 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-39091763

RESUMEN

Sustained attention, the ability to focus on a stimulus or task over extended periods, is crucial for higher level cognition, and is impaired in individuals diagnosed with neuropsychiatric and neurodevelopmental disorders, including attention-deficit/hyperactivity disorder, schizophrenia, and depression. Translational tasks like the rodent continuous performance test (rCPT) can be used to study the cellular mechanisms underlying sustained attention. Accumulating evidence points to a role for the prelimbic cortex (PrL) in sustained attention, as electrophysiological single unit and local field (LFPs) recordings reflect changes in neural activity in the PrL in mice performing sustained attention tasks. While the evidence correlating PrL electrical activity with sustained attention is compelling, limitations inherent to electrophysiological recording techniques, including low sampling in single unit recordings and source ambivalence for LFPs, impede the ability to fully resolve the cellular mechanisms in the PrL that contribute to sustained attention. In vivo endoscopic calcium imaging using genetically encoded calcium sensors in behaving animals can address these questions by simultaneously recording up to hundreds of neurons at single cell resolution. Here, we used in vivo endoscopic calcium imaging to record patterns of neuronal activity in PrL neurons using the genetically encoded calcium sensor GCaMP6f in mice performing the rCPT at three timepoints requiring differing levels of cognitive demand and task proficiency. A higher proportion of PrL neurons were recruited during correct responses in sessions requiring high cognitive demand and task proficiency, and mice intercalated non-responsive-disengaged periods with responsive-engaged periods that resemble attention lapses. During disengaged periods, the correlation of calcium activity between PrL neurons was higher compared to engaged periods, suggesting a neuronal network state change during attention lapses in the PrL. Overall, these findings illustrate that cognitive demand, task proficiency, and task engagement differentially recruit activity in a subset of PrL neurons during sustained attention.

4.
Rehabil Psychol ; 2024 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-39207423

RESUMEN

PURPOSE/OBJECTIVE: Individuals with a spinal cord injury (SCI) may experience posttraumatic stress disorder (PTSD) at a higher rate, which is associated with worse psychiatric comorbidity, decreased quality of life, and greater disability. Yet, effective PTSD interventions remain understudied for individuals with SCI. We conducted the first randomized controlled trial (RCT) of an evidence-based psychotherapy (prolonged exposure [PE]) with survivors of SCI during acute rehabilitation. We examined the efficacy, feasibility, and secondary outcomes. RESEARCH METHOD/DESIGN: Participants (n = 29) were adults recruited from 2018 to 2021 1-month postinjury with PTSD randomized into either PE therapy or treatment as usual. The primary outcome was PTSD assessed at baseline, 6, 10, and 32 weeks postenrollment. RESULTS: An overall group-by-time interaction was not statistically significant (p = .102), but effect sizes demonstrated moderate and large improvements in PTSD for the PE group at 6 (-19.4 vs. -9.7) and 10 (-25.8 vs. -5.7), respectively. Similarly, moderate to large effect sizes were observed for depression, maladaptive posttraumatic cognitions, disruptive nocturnal behaviors, SCI-related quality of life, and risky alcohol consumption. Low rates of enrollment (50%) and treatment completion (25%) suggest feasibility challenges; however, treatment completers did report high satisfaction (100%). CONCLUSIONS/IMPLICATIONS: Results suggest that individuals who received PE had a quicker and clinically meaningful reduction in PTSD symptoms, but delivery during acute rehabilitation is not feasible for many individuals. Future research should examine abbreviated versions of PE for PTSD to enhance the feasibility of treatment in this setting. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

5.
Nat Commun ; 15(1): 7342, 2024 Aug 26.
Artículo en Inglés | MEDLINE | ID: mdl-39187496

RESUMEN

Acetylcholine regulates various cognitive functions through broad cholinergic innervation. However, specific cholinergic subpopulations, circuits and molecular mechanisms underlying recognition memory remain largely unknown. Here we show that Ngfr+ cholinergic neurons in the substantia innominate (SI)/nucleus basalis of Meynert (nBM)-medial prefrontal cortex (mPFC) circuit selectively underlies recency judgements. Loss of nerve growth factor receptor (Ngfr-/- mice) reduced the excitability of cholinergic neurons in the SI/nBM-mPFC circuit but not in the medial septum (MS)-hippocampus pathway, and impaired temporal order memory but not novel object and object location recognition. Expression of Ngfr in Ngfr-/- SI/nBM restored defected temporal order memory. Fiber photometry revealed that acetylcholine release in mPFC not only predicted object encounters but also mediated recency judgments of objects, and such acetylcholine release was absent in Ngfr-/- mPFC. Chemogenetic and optogenetic inhibition of SI/nBM projection to mPFC in ChAT-Cre mice diminished mPFC acetylcholine release and deteriorated temporal order recognition. Impaired cholinergic activity led to a depolarizing shift of GABAergic inputs to mPFC pyramidal neurons, due to disturbed KCC2-mediated chloride gradients. Finally, potentiation of acetylcholine signaling upregulated KCC2 levels, restored GABAergic driving force and rescued temporal order recognition deficits in Ngfr-/- mice. Thus, NGFR-dependent SI/nBM-mPFC cholinergic circuit underlies temporal order recognition memory.


Asunto(s)
Acetilcolina , Neuronas Colinérgicas , Corteza Prefrontal , Animales , Corteza Prefrontal/metabolismo , Corteza Prefrontal/fisiología , Neuronas Colinérgicas/metabolismo , Neuronas Colinérgicas/fisiología , Acetilcolina/metabolismo , Ratones , Masculino , Ratones Noqueados , Reconocimiento en Psicología/fisiología , Núcleo Basal de Meynert/metabolismo , Núcleo Basal de Meynert/fisiología , Ratones Endogámicos C57BL , Células Piramidales/metabolismo , Células Piramidales/fisiología , Hipocampo/metabolismo , Receptores de Factor de Crecimiento Nervioso
6.
Adv Mater ; : e2409356, 2024 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-39149770

RESUMEN

Delivery of proteins in plant cells can facilitate the design of desired functions by modulation of biological processes and plant traits but is currently limited by narrow host range, tissue damage, and poor scalability. Physical barriers in plants, including cell walls and membranes, limit protein delivery to desired plant tissues. Herein, a cationic high aspect ratio polymeric nanocarriers (PNCs) platform is developed to enable efficient protein delivery to plants. The cationic nature of PNCs binds proteins through electrostatic. The ability to precisely design PNCs' size and aspect ratio allowed us to find a cutoff of ≈14 nm in the cell wall, below which cationic PNCs can autonomously overcome the barrier and carry their cargo into plant cells. To exploit these findings, a reduction-oxidation sensitive green fluorescent protein (roGFP) is deployed as a stress sensor protein cargo in a model plant Nicotiana benthamiana and common crop plants, including tomato and maize. In vivo imaging of PNC-roGFP enabled optical monitoring of plant response to wounding, biotic, and heat stressors. These results show that PNCs can be precisely designed below the size exclusion limit of cell walls to overcome current limitations in protein delivery to plants and facilitate species-independent plant engineering.

7.
Environ Sci Technol ; 58(27): 12113-12122, 2024 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-38917351

RESUMEN

Size and purity of metal phosphate and metal sulfide colloids can control the solubility, persistence, and bioavailability of metals in environmental systems. Despite their importance, methods for detecting and characterizing the diversity in the elemental composition of these colloids in complex matrices are missing. Here, we develop a single-particle inductively coupled plasma time-of-flight mass spectrometry (sp-icpTOF-MS) approach to characterize the elemental compositions of individual metal phosphate and sulfide colloids extracted from complex matrices. The stoichiometry was accurately determined for particles of known composition with an equivalent spherical diameter of ≥∼200 nm. Assisted by machine learning (ML), the new method could distinguish particles of the copper sulfides covellite (CuS), chalcocite (Cu2S), and chalcopyrite particles (CuFeS2) with 75% (for Cu2S) to 99% (for CuFeS2) accuracy. Application of the sp-icpTOF-MS method to particles recovered from natural samples revealed that iron sulfide (FeS) particles in lake sediment contained ∼4% copper and zinc impurities, whereas pure pyrite (FeS2) was identified in hydraulic fracturing wastewater and confirmed by selected area electron diffraction. Colloidal mercury in an offshore marine sediment was present as pure mercury sulfide (HgS), whereas geogenic HgS recovered from an industrial process contained ∼0.08 wt % silver per Hg, enabling source apportionment of these colloids using ML. X-ray absorption spectroscopy confirmed that Hg was predominantly present as metacinnabar (ß-HgS) in the industrial process sample. The determination of impurities in individual colloids, such as zinc and copper in FeS, and silver in HgS may enable improved assessment of their origin, reactivity, and bioavailability potential.


Asunto(s)
Coloides , Espectrometría de Masas , Fosfatos , Suelo , Sulfuros , Coloides/química , Sulfuros/química , Suelo/química , Fosfatos/química , Sedimentos Geológicos/química , Metales/química
8.
Nano Lett ; 24(26): 7833-7842, 2024 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-38887996

RESUMEN

Tobacco mild green mosaic virus (TMGMV)-like nanocarriers were designed for gene delivery to plant cells. High aspect ratio TMGMVs were coated with a polycationic biopolymer, poly(allylamine) hydrochloride (PAH), to generate highly charged nanomaterials (TMGMV-PAH; 56.20 ± 4.7 mV) that efficiently load (1:6 TMGMV:DNA mass ratio) and deliver single-stranded and plasmid DNA to plant cells. The TMGMV-PAH were taken up through energy-independent mechanisms in Arabidopsis protoplasts. TMGMV-PAH delivered a plasmid DNA encoding a green fluorescent protein (GFP) to the protoplast nucleus (70% viability), as evidenced by GFP expression using confocal microscopy and Western blot analysis. TMGMV-PAH were inactivated (iTMGMV-PAH) using UV cross-linking to prevent systemic infection in intact plants. Inactivated iTMGMV-PAH-mediated pDNA delivery and gene expression of GFP in vivo was determined using confocal microscopy and RT-qPCR. Virus-like nanocarrier-mediated gene delivery can act as a facile and biocompatible tool for advancing genetic engineering in plants.


Asunto(s)
Arabidopsis , Proteínas Fluorescentes Verdes , Arabidopsis/virología , Arabidopsis/genética , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Técnicas de Transferencia de Gen , Plásmidos/genética , Poliaminas/química , Protoplastos/metabolismo , Nanoestructuras/química , ADN/química , ADN/administración & dosificación
9.
Environ Int ; 190: 108839, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38943925

RESUMEN

The presence in seawater of low-molecular-weight polyethylene (PE) and polydimethylsiloxane (PDMS), synthetic polymers with high chemical resistance, has been demonstrated in this study for the first time by developing a novel methodology for their recovery and quantification from surface seawater. These synthetic polymer debris (SPD) with very low molecular weights and sizes in the nano- and micro-metre range have escaped conventional analytical methods. SPD have been easily recovered from water samples (2 L) through filtration with a nitrocellulose membrane filter with a pore size of 0.45 µm. Dissolving the filter in acetone allowed the isolation of the particulates by centrifugation followed by drying. The isolated SPD were analysed by 1H nuclear magnetic resonance spectroscopy (1H NMR), identifying PE and PDMS. These polymers are thus persisting on seawater because of their low density and the ponderal concentrations were quantified in mg/m3. This method was used in an actual case study in which 120 surface seawater samples were collected during two sampling campaigns in the Mediterranean Sea (from the Gulf of Salerno to the Gulf of Policastro in South Italy). The developed analytical protocol allowed achieving unprecedented simplicity, rapidity and sensitivity. The 1H and 13C NMR structural analysis of the PE debris indicates the presence of oxidised polymer chains with very low molecular weights. Additionally, the origin of those low molecular weight polymers was investigated by analysing influents and effluents from a wastewater treatment plant (WWTP) in Salerno as a hot spot for the release of SPD: the analysis indicates the presence of low molecular weight polymers compatible with wax-PE, widely used for coating applications, food industry, cosmetics and detergents. Moreover, the origin of PDMS debris found in surface seawater can be ascribed to silicone-based antifoamers and emulsifiers.


Asunto(s)
Espectroscopía de Resonancia Magnética , Agua de Mar , Agua de Mar/química , Mar Mediterráneo , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente/métodos , Polietileno/química , Polietileno/análisis , Dimetilpolisiloxanos/química , Plásticos/análisis , Plásticos/química , Polímeros/química , Polímeros/análisis
10.
Nat Nanotechnol ; 2024 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-38844663

RESUMEN

Nanocarriers (NCs) that can precisely deliver active agents, nutrients and genetic materials into plants will make crop agriculture more resilient to climate change and sustainable. As a research field, nano-agriculture is still developing, with significant scientific and societal barriers to overcome. In this Review, we argue that lessons can be learned from mammalian nanomedicine. In particular, it may be possible to enhance efficiency and efficacy by improving our understanding of how NC properties affect their interactions with plant surfaces and biomolecules, and their ability to carry and deliver cargo to specific locations. New tools are required to rapidly assess NC-plant interactions and to explore and verify the range of viable targeting approaches in plants. Elucidating these interactions can lead to the creation of computer-generated in silico models (digital twins) to predict the impact of different NC and plant properties, biological responses, and environmental conditions on the efficiency and efficacy of nanotechnology approaches. Finally, we highlight the need for nano-agriculture researchers and social scientists to converge in order to develop sustainable, safe and socially acceptable NCs.

11.
J Hazard Mater ; 474: 134746, 2024 Aug 05.
Artículo en Inglés | MEDLINE | ID: mdl-38850952

RESUMEN

Subsurface injection of colloidal activated carbon (CAC) is an in situ remediation strategy for perfluoroalkyl acids (PFAA), but the influence of groundwater solutes on longevity is uncertain, particularly for short-chain PFAA. We quantify the impact of inorganic anions, dissolved organic matter (DOM), and stabilizing polymer on PFAA adsorption to a commercial CAC. Surface characterization supported PFAA chain-length dependent adsorption results and mechanisms are provided. Inorganic anions decreased adsorption for short-chain PFAA (<7 perfluorinated carbons) due to competitive effects, while long-chain PFAA (≥ 7 perfluorinated carbons) were less impacted. DOM decreased adsorption of all PFAA in a chain-length dependent manner. High DOM concentrations (10 mg/L, ∼5 mg OC/L) decreased PFOA adsorption by a factor of 2, PFPeA by one order of magnitude, and completely hindered PFBA adsorption. High MW DOM has less impact on short-chain PFAA than low MW DOM, possibly due to differences in the ability to access CAC micropores. Low DOM concentrations (1 mg/L, ∼0.5 mg OC/L) did not impact adsorption. CMC (90 kDa average MW) had negligible impact on PFAA adsorption likely due to minimal CAC surface coverage. Longevity modeling demonstrated that groundwater solutes limit the capacity for PFAA in a CAC barrier, particularly for short-chain PFAA.

13.
J Environ Manage ; 360: 121130, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38772232

RESUMEN

Good site characterization is essential for the selection of remediation alternatives for impacted soils. The value of site characterization is critically dependent on the quality and quantity of the data collected. Current methods for characterizing impacted soils rely on expensive manual sample collection and off-site analysis. However, recent advances in terrestrial robotics and artificial intelligence offer a potentially revolutionary set of tools and methods that will help to autonomously explore natural environments, select sample locations with the highest value of information, extract samples, and analyze the data in real-time without exposing humans to potentially hazardous conditions. A fundamental challenge to realizing this potential is determining how to design an autonomous system for a given investigation with many, and often conflicting design criteria. This work presents a novel design methodology to navigate these criteria. Specifically, this methodology breaks the system into four components - sensing, sampling, mobility, and autonomy - and connects design variables to the investigation objectives and constraints. These connections are established for each component through a survey of existing technology, discussion of key technical challenges, and highlighting conditions where generality can promote multi-application deployment. An illustrative example of this design process is presented for the development and deployment of a robotic platform characterizing salt-impacted oil & gas reserve pits. After calibration, the relationship between the in situ robot chloride measurements and laboratory-based chloride measurements had a good linear relationship (R2-value = 0.861) and statistical significance (p-value = 0.003).


Asunto(s)
Robótica , Suelo , Suelo/química , Monitoreo del Ambiente/métodos , Inteligencia Artificial
14.
Sci Total Environ ; 931: 172896, 2024 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-38692327

RESUMEN

The next generation of the self-forming dynamic membrane, referred to in this study as the "Living Membrane (LM)", is a new patented technology based on an encapsulated biological layer that self-forms on a designed coarse-pore size support material during wastewater treatment and acts as a natural membrane filter. Integrating electrochemical processes with wastewater treatment using the LM approach has also been recently studied (the reactor is referred to as the Electro-Living Membrane Bioreactor or e-LMBR). This study investigated the effects of varying current densities, i.e., 0.3, 0.5, and 0.9 mA/cm2, on the performance of an e-LMBR. The results were also compared with those of the Living Membrane Bioreactor or LMBR (without applied current density). Higher pollutant removals were observed in the presence of the electric field. However, the effect of varying applied current densities on the COD (98-99 %), NH3-N (97-99 %), and PO43-P (100 %) removals was not statistically significant. The more prominent differences (p < 0.05) were observed in the decrease of NO3--N concentrations from mixed liquor to effluent, with increasing current density resulting in lower mean NO3--N effluent concentrations (0.3 mA/cm2: 6.13 mg/L; 0.5 mA/cm2: 4.38 mg/L; 0.9 mA/cm2: 3.70 mg/L). The reduction of NO3--N concentrations as wastewater permeated through the LM layer also confirmed its role in removing nitrogen-containing compounds. Higher current densities resulted in lower concentrations of fouling substances, particularly those of microbial extracellular polymeric substances (EPS) and transparent exopolymer particles (TEPs). The average values of the temporal variation of transmembrane pressure (d(TMP)/d(t)) in the e-LMBR were extremely low, in the range of 0.013-0.041 kPa/day, throughout the operation period. The highest (d(TMP)/d(t)) was observed for the highest current density. However, the TMP values remained below 2 kPa in all the e-LMBR runs even after the initial LM formation stage.


Asunto(s)
Reactores Biológicos , Membranas Artificiales , Eliminación de Residuos Líquidos , Aguas Residuales , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Incrustaciones Biológicas/prevención & control , Contaminantes Químicos del Agua/análisis
15.
Environ Sci Technol ; 58(19): 8531-8541, 2024 May 14.
Artículo en Inglés | MEDLINE | ID: mdl-38690765

RESUMEN

Colloidal activated carbon (CAC) is an emerging technology for the in situ remediation of groundwater impacted by per- and polyfluoroalkyl substances (PFAS). In assessing the long-term effectiveness of a CAC barrier, it is crucial to evaluate the potential of emplaced CAC particles to be remobilized and migrate away from the sorptive barrier. We examine the effect of two polymer stabilizers, carboxymethyl cellulose (CMC) and polydiallyldimethylammonium chloride (PolyDM), on CAC deposition and remobilization in saturated sand columns. CMC-modified CAC showed high mobility in a wide ionic strength (IS) range from 0.1 to 100 mM, which is favorable for CAC delivery at a sufficient scale. Interestingly, the mobility of PolyDM-modified CAC was high at low IS (0.1 mM) but greatly reduced at high IS (100 mM). Notably, significant remobilization (release) of deposited CMC-CAC particles occurred upon the introduction of solution with low IS following deposition at high IS. In contrast, PolyDM-CAC did not undergo any remobilization following deposition due to its favorable interactions with the quartz sand. We further elucidated the CAC deposition and remobilization behaviors by analyzing colloid-collector interactions through the application of Derjaguin-Landau-Verwey-Overbeek theory, and the inclusion of a discrete representation of charge heterogeneity on the quartz sand surface. The classical colloid filtration theory was also employed to estimate the travel distance of CAC in saturated columns. Our results underscore the roles of polymer coatings and solution chemistry in CAC transport, providing valuable guidelines for the design of in situ CAC remediation with maximized delivery efficiency and barrier longevity.


Asunto(s)
Coloides , Restauración y Remediación Ambiental , Agua Subterránea , Agua Subterránea/química , Coloides/química , Restauración y Remediación Ambiental/métodos , Polímeros/química , Carbón Orgánico/química , Arena/química , Contaminantes Químicos del Agua/química , Carbono/química
16.
J Environ Manage ; 357: 120830, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38583383

RESUMEN

Greenhouse gases (GHGs) emissions due to increasing energy demand have raised the need to identify effective solutions to produce clean and renewable energy. Biotechnologies are an effective platform to attain green transition objectives, especially when synergically integrated to promote health and environmental protection. In this context, microalgae-based biotechnologies are considered among the most effective tools for treating gaseous effluents and simultaneously capturing carbon sources for further biomass valorisation. The production of biodiesel is regarded as a promising avenue for harnessing value from residual algal biomass. Nonetheless, the existing techniques for extracting lipids still face certain limitations, primarily centred around the cost-effectiveness of the process.This study is dedicated to developing and optimising an innovative and cost-efficient technique for extracting lipids from algal biomass produced during gaseous emissions treatment based on algal-bacterial biotechnology. This integrated treatment technology combines a bio-scrubber for degrading gaseous contaminants and a photobioreactor for capturing the produced CO2 within valuable algal biomass. The cultivated biomass is then processed with the process newly designed to extract lipids simultaneously transesterificated in fatty acid methyl esters (FAME) via In Situ Transesterification (IST) with a Kumagawa-type extractor. The results of this study demonstrated the potential application of the optimised method to overcome the gap to green transition. Energy production was obtained from residuals produced during the necessary treatment of gaseous emissions. Using hexane-methanol (v/v = 19:1) mixture in the presence KOH in Kumagawa extractor lipids were extracted with extraction yield higher than 12% and converted in fatty acid methyl esters. The process showed the enhanced extraction of lipids converted in bio-sourced fuels with circular economy approach, broadening the applicability of biotechnologies as sustainable tools for energy source diversification.


Asunto(s)
Lípidos , Microalgas , Biocombustibles , Promoción de la Salud , Ácidos Grasos , Gases , Biomasa , Ésteres
19.
Water Res ; 254: 121367, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38417268

RESUMEN

Differential absorption spectroscopy (DAS) quantifies changes in the UV-Visible absorbance of dissolved organic matter (DOM) caused by reactions of its chromophores. As a result of its precision and sensitvity, DAS serves as a powerful tool for characterizing the formation of disinfection by-products (DBPs) in generated in DOM chlorination reactions. However, the nonlinear relationship between the intensity of DAS and DBP concentrations as well as the need to develop site-specific fitting parameters limit its practical applications. This study investigated the physico-chemical nature of DAS of chlorinated DOM through experimental measurements and theoretical calculations. Results of this study provide molecular-level evidence that electrophilic substitution reactions involving DOM reactive sites result in the emergence of DAS feaures ascribed to the "fast" chromophores. The ring opening in the cyclic enones-like structures which can be present either in the original DOM or are generated as intermediates in its chlorination, leads to the emergence of DAS features associated with the "slow" chromophores and high yields of DBPs. The kinetic study of chlorination of real waters reveals a strong linear relationship (R2 > 0.91) between ln([DBP]) and the long-wavelength (λ > 325 nm) parameter of the DAS, notably (ln(-DA350)). This relationship varies among different water sources due to the differences in the heterogeneity of Band A3 whose maximum is near 350 nm. Band A3 is one of the Gaussian bands that comprise the overall UV-Visible spectrum of DOM. A new function (f(-DA350)) is proposed in this study to quantify DBP formation. This function, which is determined by the Band A3's area, allows establishing a universal linear relationship between f(-DA350) and ln([THMs]), as well as f(-DA350) and ln([HAAs]), across various water sources. The findings of this study will stimulate further development of spectroscopy-based DBP monitoring technology for monitoring and optimization of water disinfection processes.


Asunto(s)
Purificación del Agua , Purificación del Agua/métodos , Desinfección , Aminas , Agua/química
20.
Environ Sci Technol ; 2024 Feb 10.
Artículo en Inglés | MEDLINE | ID: mdl-38340051

RESUMEN

Here, isotopically labeled 68ZnO NPs (ZnO NPs) and 68ZnO NPs with a thin 68Zn3(PO4)2 shell (ZnO_Ph NPs) were foliarly applied (40 µg Zn) to pepper plants (Capsicum annuum) to determine the effect of surface chemistry of ZnO NPs on the Zn uptake and systemic translocation to plant organs over 6 weeks. Despite similar dissolution of both Zn-based NPs after 3 weeks, the Zn3(PO4)2 shell on ZnO_Ph NPs (48 ± 12 nm; -18.1 ± 0.6 mV) enabled a leaf uptake of 2.31 ± 0.34 µg of Zn, which is 2.7 times higher than the 0.86 ± 0.18 µg of Zn observed for ZnO NPs (26 ± 8 nm; 14.6 ± 0.4 mV). Further, ZnO_Ph NPs led to higher Zn mobility and phloem loading, while Zn from ZnO NPs was stored in the epidermal tissues, possibly through cell wall immobilization as a storage strategy. These differences led to higher translocation of Zn from the ZnO_Ph NPs within all plant compartments. ZnO_Ph NPs were also more persistent as NPs in the exposed leaf and in the plant stem over time. As a result, the treatment of ZnO_Ph NPs induced significantly higher Zn transport to the fruit than ZnO NPs. As determined by spICP-TOFMS, Zn in the fruit was not in the NP form. These results suggest that the Zn3(PO4)2 shell on ZnO NPs can help promote the transport of Zn to pepper fruits when foliarly applied. This work provides insight into the role of Zn3(PO4)2 on the surface of ZnO NPs in foliar uptake and in planta biodistribution for improving Zn delivery to edible plant parts and ultimately improving the Zn content in food for human consumption.

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