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1.
Zhongguo Zhong Yao Za Zhi ; 46(15): 3764-3771, 2021 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34472248

RESUMO

The purpose of the present study was to investigate the relationship of the classification of traditional Chinese medicine(TCM) materials with the suitable binder concentration and dosage in the preparation of personalized water-paste pills and establish a model for predicting the binder concentration and dosage. Five representative TCM materials were selected, followed by mixture uniform design. The water-paste pills were prepared by extrusion and spheronization with hypromellose E5(HPMC E5) as the binder. The quality of intermediates and final products was evaluated, and the resulting data were subjected to multivariate statistical analysis. The prediction models for binder concentration and dosage were established as follows: binder concentration: Y_1=0.378 6 + 0.570 1X_A + 2.271 2X_B-0.894 5X_C-0.458 2X_D-1.145 4X_E(when Y_1 < 0, 10% HPMC E5 was required; when Y_1 > 0, 20% HPMC E5 was required), with the accuracy reaching up to 100%; binder dosage: Y_2=32.38 + 0.25X_A + 1.85X_B-0.013X_B~2-0.002 5X_C~2(R~2=0.932 6, P < 0.001). The results showed that the binder concentration and dosage were correlated positively with the proportion of fiber material but negatively with the proportions of sugar material and brittle material. Then the validation experiments were conducted with the prediction models and all the prescriptions could be successfully prepared at one time. These demonstrated that following the classification of TCM materials and the calculation of their proportions in the prescription, the established mathematical model could be adopted for predicting the binder concentration and dosage required in the preparation of personalized water-paste pills, which contributed to reducing the pre-formulation research and guiding the actual production of personalized water-paste pills.


Assuntos
Medicamentos de Ervas Chinesas , Medicina Tradicional Chinesa , Excipientes , Derivados da Hipromelose , Água
2.
Zhongguo Zhong Yao Za Zhi ; 46(15): 3772-3779, 2021 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-34472249

RESUMO

To explore the correlation between concentrate viscosity and molding quality of personalized traditional Chinese medicine(TCM) condensed water pill, this study established a concentrate viscosity characterization method with rotational rheometry. Seven model prescriptions were respectively concentrated to different degrees and the viscosity of each concentrate was determined. The pre-sence of 'viscosity jump' in the middle stage of 'flag hanging' of all the model prescriptions implied that there might be an ideal viscosity range in the preparation of condensed water pill. The further study of 22 model prescriptions demonstrated that the optimum viscosity range of concentrate was 5-15 Pa·s(25 ℃) for approximately 82% of the prescriptions. About 18% of the prescriptions had a wide range, which might be caused by the high proportions of mineral and crustacean drugs in the crushing part and sugar and fibrous drugs in the decocting part. This study clarified the optimum viscosity range for concentrates of personalized TCM condensed water pills and achieved a preparation technology without any excipient, laying a foundation for the on-line control of the preparation.


Assuntos
Medicamentos de Ervas Chinesas , Medicina Tradicional Chinesa , Excipientes , Viscosidade , Água
3.
Nanoscale ; 13(34): 14297-14303, 2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34473172

RESUMO

The application of perovskite quantum dots (PQDs) in biomedical fields such as bioimaging and biosensing has been limited owing to their instability in the physiological environment. Herein, PQDs are innovatively encapsulated into nano-micelles composed of a polyethylene glycol-polycaprolactone (PEG-PCL) block copolymer, which allows the preparation of biocompatible PQDs (bio-PQDs) with excellent water resistance. Due to the benefits of extraordinary water resistance and biocompatibility, these bio-PQDs are capable of real-time and long-term quantitatively monitoring the H2S level in living cells as well as in zebrafish.


Assuntos
Pontos Quânticos , Animais , Compostos de Cálcio , Óxidos , Pontos Quânticos/toxicidade , Titânio , Água , Peixe-Zebra
4.
Braz J Biol ; 83: e253009, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34495170

RESUMO

Today, global focus of research is to explore the solution of energy crisis and environmental pollution. Like other agricultural countries, bulk quantities of watermelon peels (WMP) are disposed-off in environment as waste in Pakistan and appropriate management of this waste is the need of hour to save environment from pollution. The work emphasizes the role of ethanologenic yeasts to utilize significant sugars present in WMP for low-cost bioethanol fermentation. Dilute hydrochloric acid hydrolysis of WMP was carried out on optimized conditions employing RSM (response surface methodology) following central composite design (CCD). This experimental design is based on optimization of ethanologenesis involving some key independent parameters such as WMP hydrolysate and synthetic media ratio (X1), incubation temperature (X2) and incubation temperature (X3) for maximal ethanol yield exploiting standard (Saccharomyces cerevisiae K7) as well as experimental (Metchnikowia cibodasensisY34) yeasts. The results revealed that maximal ethanol yields obtained from S. cerevisiae K7 was 0.36±0.02 g/g of reducing sugars whereas M. cibodasensisY34, yielded 0.40±0.01 g ethanol/g of reducing sugars. The yeast isolate M. cibodasensisY34 appeared as promising ethanologen and embodies prospective potential for fermentative valorization of WMP-to-bioethanol.


Assuntos
Cucurbitaceae , Etanol , Biotransformação , Fermentação , Estudos Prospectivos , Saccharomyces cerevisiae , Água
5.
An Acad Bras Cienc ; 93(4): e20190479, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34495195

RESUMO

This study was carried out to determine the toxicity and biochemical and morphophysiological changes caused by Serjania erecta leaf aqueous extract in pacu (Piaractus mesopotamicus). For acute toxicity testing (CL50-4h), pacu juveniles were exposed during 4 h to Serjania erecta aqueous extract concentrations of 2.5, 12.5, 25, 50, 100, and 150 µg mL-1, which were added directly to the water in the tanks. In the control group, the animals were kept in water free from aqueous extract. CL50-4 h was estimated at 57.43 µg mL-1. After exposure to the aqueous extract, the highest (P<0.05) glucose concentration and the lowest (P<0.05) plasma sodium level were when the fish were exposed to the S. erecta concentration of 50 µg mL-1. Mortality occurred at S. erecta extract levels higher than 50 µg mL-1, and all fish died at concentrations greater than 100 µg mL-1. In addition, exposure to this extract caused severe histological changes in the gills and liver with higher prevalence of necrosis (30.2%), and fatty degeneration (77.4%) respectively. At the concentrations tested here, S. erecta aqueous extract causes morphofunctional alterations in this fish species.


Assuntos
Caraciformes , Sapindaceae , Animais , Folhas de Planta , Água
6.
An Acad Bras Cienc ; 93(4): e20190667, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34495196

RESUMO

The Cerrado/Caatinga transition region in Piauí State has a high potential for production of food, fiber and energy, representing about 19% of the total area of the State. This work aimed to evaluate physical and hydraulic attributes under different crops in Latossolo Amarelo Distrófico (Oxisol) in cerrado/caatinga transition areas, in the Southwest of Piauí. In this study five areas with different crops were evaluated as follows: areas under pasture crop with Andropogon gayanus grass with three and six years of crop, area under intensive crop of Pennisetum purpureum grass, area under orchard of Annona squamosa L., area under intensive crop irrigated with central pivot and area under native vegetation of cerrado/caatinga ecotone representing a condition of equilibrium. Soil attributes evaluated were: soil density, total porosity, macroporosity, microporosity, unsaturated pores, blocked pores, saturation humidity, effective saturation, water readily available, void index, mechanical resistance of soil and saturated field hydraulic conductivity. The intensive crop of napier grass for five consecutive years and the pivot irrigated area under intensive crop for four years presented the greatest negative impacts on soil density, total porosity, macroporosity, saturation humidity, effective saturation, water readily available and index of voids.


Assuntos
Produtos Agrícolas , Solo , Brasil , Água
7.
Sensors (Basel) ; 21(17)2021 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-34502585

RESUMO

The topic of underwater (UW) image colour correction and restoration has gained significant scientific interest in the last couple of decades. There are a vast number of disciplines, from marine biology to archaeology, that can and need to utilise the true information of the UW environment. Based on that, a significant number of scientists have contributed to the topic of UW image colour correction and restoration. In this paper, we try to make an unbiased and extensive review of some of the most significant contributions from the last 15 years. After considering the optical properties of water, as well as light propagation and haze that is caused by it, the focus is on the different methods that exist in the literature. The criteria for which most of them were designed, as well as the quality evaluation used to measure their effectiveness, are underlined.


Assuntos
Água , Cor
8.
Water Res ; 203: 117488, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34482236

RESUMO

The biodegradability of the anticonvulsant pregabalin (PGB) was studied in laboratory incubation experiments in contact with water/sediment systems under different redox conditions. PGB was degraded by biological processes under aerobic conditions reaching half-lives of 8 to 10 d, while inactivated and anaerobic control experiments revealed no significant decrease of PGB concentrations. Within experiments spiked with elevated PGB concentrations, 12 TPs were formed and tentative chemical structures could be proposed by accurate masses and fragmentation pathways detected via measurements with high resolution mass spectrometry (LC-QToF-MS). Four of the proposed TPs were finally confirmed either by authentic reference standards (PGB-Lactam, ISA, TP 157-A (II)) or a self-synthesized standard (NA-PGB). PGB-Lactam was identified as the quantitatively most relevant TP formed via intramolecular cyclization under aerobic conditions, reaching up to 33% of the initial PGB concentration. Incubation experiments spiked with PGB-Lactam revealed three times higher half-lives compared to the parent compound, indicating that PGB-Lactam is more stable than PGB. A comparison with results gained from water/sediment incubation experiments with the structurally related compound gabapentin (GBP) revealed, that the transformation behaviour can be mainly extrapolated to PGB. Most of the observed transformation reactions found for PGB were comparable to the ones found for GBP. The TPs PGB-Lactam and NA-PGB as well as three GBP TPs (GBP-Lactam, NA-GBP and CCHA) have been detected in German wastewater treatment plants (WWTPs) effluents and the river Rhine including some of its tributaries such as Main, Neckar, Moselle and Aare. Moreover, GBP and PGB as well as some of their TPs were detected in German bank filtrates and finished drinking waters up to 260 ng L-1. For that reason these compounds should be monitored in drinking water in the future.


Assuntos
Poluentes Químicos da Água , Água , Biotransformação , Gabapentina , Pregabalina , Rios , Águas Residuárias , Poluentes Químicos da Água/análise
9.
Environ Monit Assess ; 193(10): 642, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34508274

RESUMO

The present research describes the successful preparation of melon peel biochar modified with CoFe2O4 (MPBC/CoFe2O4) followed by its usage as a new sorbent to separate, preconcentrate, and determine the toxic heavy metal ions by magnetic solid-phase extraction. The metal ion desorption was performed by 0.1 M HCl solution with a volume of 5.0 mL. Flame atomic absorption spectrometry (FAAS) was utilized for detection of the analyte levels. SEM-EDX, TEM, XRD, and FTIR techniques were carried out to illuminate the structure of MPBC/CoFe2O4. The fundamental variables affecting the adsorption and elution efficiencies of the analyte ions including solution pH, MPBC/CoFe2O4 amount, type and concentration of eluent, adsorption and desorption equilibrium time, and sample volume were optimized. The detection limits were calculated as 0.41, 1.82, and 3.16 µg L-1 for Cu2+, Cd2+, and Pb2+ ions, respectively, with the relative standard deviation of lower than 4.2%. There were no substantial interference effects on the analyte ion recovery due to the presence of foreign ions at high levels. Five minutes of contact time was adequate to attain the adsorption equilibrium. The adsorption capacity of MPBC/CoFe2O4 was obtained as 106.4, 65.4, and 188.7 mg g-1 for Cu2+, Cd2+, and Pb2+ ions, respectively, by utilizing Langmuir isotherm model. The pseudo-second order model is favorable to identify the adsorption kinetics. The method was validated by spike/recovery test, and then, it was successfully implemented to determine the aforementioned analyte levels in sea and stream water, pepper, black cabbage, eggplant, and tomato samples.


Assuntos
Cucurbitaceae , Poluentes Químicos da Água , Adsorção , Cádmio/análise , Carvão Vegetal , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Chumbo , Extração em Fase Sólida , Espectrofotometria Atômica , Verduras , Água , Poluentes Químicos da Água/análise
10.
Sci Total Environ ; 792: 148543, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465035

RESUMO

The preparation of an adsorbent with highest efficiency, selectivity and stability is usually a challenging task. Herein, we prepared a thio functionalized layered double hydroxide (LDH) denoted as S2O4 LDH by intercalating a strong reducing agent (S2O42-) in the interlayers of trimetallic LDH and was applied to capture vanadium (V(V)) oxyanions from aqueous medium of diverse conditions. The successful preparation of the adsorbent was first confirmed using XRD, FTIR, EDX and CHS analyses. The results revealed that the modified LDH showed excellent performance at a wider pH range which can avoid the tedious work of adjusting pH in actual industrial wastewater treatment. The adsorption capacity was increased with temperature and obtained 379.55 mg/g at 323 K comparing to 112.3 mg/g at 293 K. The adsorption isotherm was better fitted to Langmuir model which suggested monolayer adsorption behavior. At lower temperature (293 K), the sorption kinetics were fitted to a pseudo-first order reaction model which implied physisorption reaction while at higher temperatures (303 and 323 K), the reaction order fitted to pseudo-second order reaction model which highlighted the chemisorption reaction mechanism. As confirmed using XRD, FTIR, EDX and XPS instrumental techniques, the dominant removal mechanism of V(V) involved ion-exchange and partial reduction reactions to nontoxic and less soluble V(IV) and V(III) species due to the low valent sulfur group and followed adsorption in S2O4 LDH. The prepared adsorbent showed very good selectivity towards V(V) in the presence of different co-existing ions both in synthetic wastewater and spiked real water samples. This novel adsorbent also exhibited high recyclability and obtained >90.0% removal of V(V) after four consecutive adsorption-desorption cycles due to the unique memory effect of the LDH. We believe that this strategy provides a new direction to find highly efficient and selective materials for capturing vanadium ions from wastewater of diverse conditions.


Assuntos
Vanádio , Poluentes Químicos da Água , Adsorção , Elétrons , Concentração de Íons de Hidrogênio , Hidróxidos , Cinética , Sulfetos , Água , Poluentes Químicos da Água/análise
11.
Sci Total Environ ; 792: 148458, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465045

RESUMO

The Brazilian semiarid region presents a physical water scarcity and high seasonal and interannual irregularities of precipitation, known as a region with periodic droughts. This region is mainly covered by the Caatinga biome, recognized as a Seasonally Dry Tropical Forest (SDTF). Soil water availability directly impacts the ecosystem's functioning, characterized by low fertility and sparse vegetation cover during the dry season, making it a fragile ecosystem vulnerable to climatic variations. Additionally, this region has been suffering from several issues due to human activities over the centuries, which has resulted in extensive areas being severely degraded, which aggravates the impacts from climatic variations and the susceptibility to desertification. Thus, studying the soil-plant-atmosphere continuum in this region can help better understand the seasonal and annual behavior of the water and carbon fluxes. This study investigated the dynamics of water and carbon fluxes during four years (2013-2016) by using eddy covariance (EC) measurements within two areas of Caatinga (dense Caatinga (DC) and sparse Caatinga (SC)) that suffered anthropic pressures. The two study areas showed similar behavior in relation to physical parameters (air temperature, incoming radiation, vapor pressure deficit, and relative humidity), except for soil temperature. The SC area presented a surface temperature of 3 °C higher than the DC, related to their vegetation cover differences. The SC area had higher annual evapotranspiration, representing 74% of the precipitation for the DC area and 90% for the SC area. The two areas acted as a carbon sink during the study period, with the SC area showing a lower CO2 absorption capacity. On average, the DC area absorbs 2.5 times more carbon than the SC area, indicating that Caatinga deforestation affects evaporative fluxes, reducing atmospheric carbon fixation and influencing the ability to mitigate the effects of increased greenhouse gas concentrations in the atmosphere.


Assuntos
Ecossistema , Solo , Carbono , Ciclo do Carbono , Humanos , Água
12.
Sci Total Environ ; 792: 148462, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465053

RESUMO

Graphitic carbon nitride (g-C3N4) has gained enormous attention for water and wastewater treatment. Compared with g-C3N4 nanopowders, g-C3N4 based hybrid membranes have demonstrated great potential for its superior practicability. This review outlines the preparation and characterization of g-C3N4 based hybrid membranes and presents their representative applications in water and wastewater treatment (e.g., removal of organic dyes, phenolic compounds, pharmaceuticals, salt ions, heavy metals, and oils). Meanwhile, g-C3N4 based films for the removal of contaminants through photocatalytic degradation is also summarized. In addition, the corresponding mechanisms and relevant findings are discussed. Finally, the challenges and research needs in the future and application of g-C3N4 based hybrid membranes are highlighted.


Assuntos
Purificação da Água , Água , Catálise , Grafite , Compostos de Nitrogênio
13.
J Environ Sci (China) ; 108: 107-119, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34465425

RESUMO

The promising solar irradiated photocatalyst by pairing of bismuth oxide quantum dots (BQDs) doped TiO2 with nitrogen doped graphene oxide (NGO) nanocomposite (NGO/BQDs-TiO2) was fabricated. It was used for degradation of organic pollutants like 2,4-dichlorophenol (2,4-DCP) and stable dyes, i.e. Rhodamine B and Congo Red. X-ray diffraction (XRD) profile of NGO showed reduction in oxygenic functional groups and restoring of graphitic crystal structure. The characteristic diffraction peaks of TiO2 and its composites showed crystalline anatase TiO2. Morphological images represent spherical shaped TiO2 evenly covered with BQDs spread on NGO sheet. The surface linkages of NO-O-Ti, C-O-Ti, Bi-O-Ti and vibrational modes are observed by Fourier transform infrared spectroscopy (FTIR) and Raman studies. BQDs and NGO modified TiO2 results into red shifting in visible region as studied in diffused reflectance spectroscopy (DRS). NGO and BQDs in TiO2 are linked with defect centers which reduced the recombination of free charge carriers by quenching of photoluminescence (PL) intensities. X-ray photoelectron spectroscopy (XPS) shows that no peak related to C-O in NGO/BQDs-TiO2 is observed. This indicated that doping of nitrogen into GO has reduced some oxygen functional groups. Nitrogen functionalities in NGO and photosensitizing effect of BQDs in ternary composite have improved photocatalytic activity against organic pollutants. Intermediate byproducts during photo degradation process of 2,4-DCP were studied through high performance liquid chromatography (HPLC). Study of radical scavengers indicated that O2·- has significant role for degradation of 2,4-DCP. Our investigations propose that fabricated nanohybrid architecture has potential for degradation of environmental pollutions.


Assuntos
Nitrogênio , Água , Catálise , Luz , Titânio
14.
Mater Sci Eng C Mater Biol Appl ; 128: 112355, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474903

RESUMO

Electrostatically driven self-assembly of [Au2L2]2+ (L is cyclic PNNP ligand) with [{Mo6I8}(L')6]2- (L' = I-, CH3COO-) in aqueous solutions is introduced as facile route for combination of therapeutic and cellular contrasting functions within heterometallic colloids (Mo6-Au2). The nature of L' affects the size and aggregation behavior of crystalline Mo6-Au2 aggregates, which in turn affect the luminescence of the cluster units incorporated into Mo6-Au2 colloids. The spin trap facilitated electron spin resonance spectroscopy technique indicates that the level of ROS generated by Mo6-Au2 colloids is also affected by their size. Both (L' = I-, CH3COO-) Mo6-Au2 colloids undergo cell internalization, which is enhanced by their assembly with poly-DL-lysine (PL) for L' = CH3COO-, but remains unchanged for L' = I-. The colloids PL-Mo6-Au2 (L' = CH3COO-) are visualized as huge crystalline aggregates both outside and inside the cell cytoplasm by confocal microscopy imaging of the incubated cells, while the smaller sized (30-50 nm) PL-Mo6-Au2 (L' = I-) efficiently stain the cell nuclei. Quantitative colocalization analysis of PL-Mo6-Au2 (L' = CH3COO-) in lysosomal compartments points to the fast endo-lysosomal escape of the colloids followed by their intracellular aggregation. The cytotoxicity of PL-Mo6-Au2 differs from that of Mo6 and Au2 blocks, predominantly acting through apoptotic pathway. The photodynamic therapeutic effect of the PL-Mo6-Au2 colloids on the cancer cells correlates with their intracellular trafficking and aggregation.


Assuntos
Fotoquimioterapia , Coloides , Luminescência , Polímeros , Água
15.
Chemosphere ; 282: 131066, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470152

RESUMO

Copper ion (Cu2+), a common corrosion product released from copper pipes, is widely present in water distribution system (WDS). Cu2+ was confirmed to be capable to catalyze the decay of monochloramine (NH2Cl), which is a commonly used disinfectant and need to maintain a minimum concentration in WDS. Cu2+ and NH2Cl form a system in WDS and their interaction with other substances in WDS is unclear. In this study, the performance of Cu2+/NH2Cl system on degradation of trace pollutants, taking carbamazepine (CBZ) as an example, in WDS was investigated, and significant promotion on CBZ degradation was observed. The acceleration was due to the generation of Cl, OH and other oxidants, which were identified by scavenge experiments. CBZ degradation in Cu2+/NH2Cl system was highly pH-dependent, because the catalytic effect of Cu2+ can only work at low pH (Cu2+ precipitating at pH > 6.0). The removal of CBZ increased with the concentration of Cu2+ increasing. Water matrix (NOM, HCO3- and Br-) can inhibit the removal of CBZ in Cu2+/NH2Cl system. Further, five disinfection byproducts (DBPs), namely, trichloromethane (TCM), dichloroacetonitrile (DCAN), dichloroacetone (DCP), trichloronitromethane (TCNM) and trichloroacetone (TCP), were detected in chloramination in the presence/absence of Cu2+. Compared with chloramination without Cu2+, the cytotoxicity and genotoxicity of formed DBPs increased significantly in the presence of Cu2+, indicating that the chemical safety in WDS deserves more attention.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Carbamazepina , Cobre , Corrosão , Desinfecção , Halogenação , Água , Poluentes Químicos da Água/análise
16.
Chemosphere ; 282: 131092, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470156

RESUMO

Remediation of heavy metal contaminated soil with appropriate washing agents is crucial to the decline in the harmfulness of contaminated soil by heavy metals to the environment and human health. In this study, citric acid (CA) and water-soluble chitosan (WSCS) as natural and degradable washing agents were used to remove Zn in the soil by two-step washing method. Results indicated that the two-step washing with CA and WSCS were found to be suitable for the removal of Zn from the contaminated soils, which significantly decreased the total concentration of Zn in the soil. After the remediation process with two-step soil washing, the contents of Zn in different chemical species decreased, especially for the carbonate-bound fraction. Therefore, the two-step soil washing with CA and WSCS was advisable for the remediation of Zn-contaminated soils. The washing mechanism could include the acid dissolution, ion exchange and complexation reaction between zinc ions and functional groups such as hydroxyl, carboxyl, amine and amide groups. This study provided the theoretical support for the exploitation and application of suitable washing agents used for the remediation of contaminated soils by heavy metals.


Assuntos
Quitosana , Recuperação e Remediação Ambiental , Metais Pesados , Poluentes do Solo , Ácido Cítrico , Humanos , Metais Pesados/análise , Solo , Poluentes do Solo/análise , Água , Zinco
17.
Chemosphere ; 282: 131131, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470169

RESUMO

This is an integrated assessment of the distribution of Cd, Cr, Hg and Pb in dissolved water, sediments and muscle fish tissues (Cynoscion guatucupa, Micropogonias furnieri, Mustelus schmitti and Ramnogaster arcuata) from the Bahía Blanca estuary, Argentina. Within the water fraction (µg L-1), Hg and Pb concentrations ranged from below the limit of detection (

Assuntos
Metais Pesados , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Peixes , Sedimentos Geológicos , Metais Pesados/análise , Água , Poluentes Químicos da Água/análise
18.
Molecules ; 26(17)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34500625

RESUMO

The photophysical relaxation mechanisms of 1-cyclohexyluracil, in vacuum and water, were investigated by employing the Multi-State CASPT2 (MS-CASPT2, Multi-State Complete Active-Space Second-Order Perturbation Theory) quantum chemical method and Dunning's cc-pVDZ basis sets. In both environments, our results suggest that the primary photophysical event is the population of the S11(ππ*) bright state. Afterwards, two likely deactivation pathways can take place, which is sustained by linear interpolation in internal coordinates defined via Z-Matrix scans connecting the most important characteristic points. The first one (Route 1) is the same relaxation mechanism observed for uracil, its canonical analogue, i.e., internal conversion to the ground state through an ethylenic-like conical intersection. The other route (Route 2) is the direct population transfer from the S11(ππ*) bright state to the T23(nπ*) triplet state via an intersystem crossing process involving the (S11(ππ*)/T23(nπ*))STCP singlet-triplet crossing point. As the spin-orbit coupling is not too large in either environment, we propose that most of the electronic population initially on the S11(ππ*) state returns to the ground following the same ultrafast deactivation mechanism observed in uracil (Route 1), while a smaller percentage goes to the triplet manifold. The presence of a minimum on the S11(ππ*) potential energy hypersurface in water can help to understand why experimentally it is noticed suppression of the triplet states population in polar protic solvent.


Assuntos
Pirimidinas/química , Uracila/análogos & derivados , Teoria Quântica , Solventes/química , Termodinâmica , Uracila/química , Água/química
19.
Molecules ; 26(17)2021 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-34500638

RESUMO

The effect of humidity on sheep wool during irradiation by an accelerated electron beam was examined. Each of the samples with 10%, 53%, and 97% relative humidity (RH) absorbed a dose of 0, 109, and 257 kGy, respectively. After being freely kept in common laboratory conditions, the samples were subjected to batch Co(II) sorption experiments monitored with VIS spectrometry for different lapses from electron beam exposure. Along with the sorption, FTIR spectral analysis of the wool samples was conducted for cysteic acid and cystine monoxide, and later, the examination was completed, with pH measuring 0.05 molar KCl extract from the wool samples. Besides a relationship to the absorbed dose and lapse, the sorptivity results showed considerable dependence on wool humidity under exposure. When humidity was deficient (10% RH), the sorptivity was lower due to limited transformation of cystine monoxide to cysteic acid. The wool pre-conditioned at 53% RH, which is the humidity close to common environmental conditions, demonstrated the best Co(II) sorptivity in any case. This finding enables the elimination of pre-exposure wool conditioning in practice. Under excessive humidity of 97% RH and enough high dose of 257 kGy, radiolysis of water occurred, deteriorating the sorptivity. Each wool humidity, dose, and lapse showed a particular scenario. The time and humidity variations in the sorptivity for the non-irradiated sample were a little surprising; despite the absence of electron irradiation, relevant results indicated a strong sensitivity to pre-condition humidity and lapse from the start of the monitoring.


Assuntos
Cobalto/química , Íons/química , Ovinos/metabolismo , Lã/química , Adsorção/fisiologia , Animais , Cistina/química , Elétrons , Umidade , Água/química
20.
J Environ Manage ; 298: 113423, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34526286

RESUMO

The Yellow River, with a developmental and historical significance to China, is now facing several emerging pressures, which are degrading the river status and creating challenges for high-quality development in the basin. Numerous studies on such emerging pressures, present scattered outcomes, and trigger uncertainties and deficient assumptions on the river's problems. This review integrated such scattered information and investigated the emerging pressures, their drivers and integrated impacts at the basin level. The study intended to prioritize those pressures needing expeditious consideration, and carried a discussion on the alternative pathways to the solution. To determine the critical emerging pressures, a literature review was conducted and experts' opinion was sought. The outcome further led to a comprehensive review, data collection, and analysis of three groups of emerging pressures. The review recognized 'Water Stress' in the lower reach, primarily caused by an abated flow, as the most distressing emerging pressure inflicting social, ecological, and economic consequences. Such decline in flow was mostly induced by a recent increase in 'Anthropogenic activities', such as intensive water withdrawal for irrigation (≥27 BCM), and construction of check dams in the Loess Plateau region (trapping~5 BCM water). The increasing 'Pollution' in the river, besides threatening public health and ecology, also contributed to the water stress by rendering certain stretches of the river biologically dead and unsuitable for any use. The 'Climate Change', with its key negative effect on precipitation in the middle sub-basin, overall contributed small (8-11 %) to the observed reduction in river flow. With increasing challenges for the adopted engineering solutions tackling the water stress, the study suggested the use of a demand management approach, employing adaptive policy measures, as an alternative or supplementary solution to the current approach. In addition, the study highlights that regular reviewing and reforming the key decisions based on evidence and updated information, and taking a participatory approach, may offer a sustainable pathway to the environment as well as socio-economic goals.


Assuntos
Rios , Movimentos da Água , Mudança Climática , Ecologia , Água
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