Search

The mechanism of how porosity affects EM wave absorption was investigated with a quantitative random network model.

MOF-derived carbon materials with unique structures are prepared by salt-assisted pyrolysis and exhibit excellent microwave absorbing performance with an effective absorption bandwidth of 6.23 GHz at lower fill ratios of 7%.

Bromophenols (BPs) have both natural and artificial sources in the environment and are frequently detected in plants. Herein, the ubiquitous 2,4,6-TriBP was hydroponically exposed to rice seedlings at two concentrations (0.2 and 2.0 mg/L) to characterize the dose-dependent abiotic stress responses of rice plants to BPs. The 2,4,6-TriBP induced oxidative damage to rice roots and subsequently inhibited plant transpiration and growth at the end of exposure in both concentrations. Moreover, the gene expression of

As a widely applied semiconductor nanomaterial, quantum dots (QDs) have drawn considerable interest. In this study, pumpkin and rice seedlings were hydroponically exposed to two core/shell CdSe/ZnS QDs coated with cysteamine (CdSe/ZnS-CA) and polyethylene glycol-carboxy (CdSe/ZnS-PEG-COOH) for 10 days to analyze their time-varying uptake, translocation, and transformation behaviors in plants. Both QDs were mainly adsorbed/absorbed by the roots in the particulate state, and more CdSe/ZnS-CA accumulated than CdSe/ZnS-PEG-COOH. For CdSe/ZnS-CA-treated plants, the Se and Cd concentrations (C

There are numerous application prospects for black phosphorus (BP) in biomedical and agricultural fields. Here, the dispersion stability of BP nanosheets (BPNSs) in the root zone, which is essential for its bioactivity in plants, was investigated using the root exudates of rice, pumpkin, and soybean with the presence of a common environmental ion (Ca2+). The results showed that those root exudates inhibited the aggregation of BPNSs. The critical coagulation concentrations (CCCs) of Ca2+ for BPNSs dispersed in solutions with root exudates of rice and pumpkin increased over 97 times higher than that without exudates. Soybean exudates exhibited the strongest aggregation inhibition effects, as the aggregation behavior of BPNSs was maintained in the reaction-limited regime in the tested Ca2+ concentration range (1.28 × 104–9.62 × 104 mg L−1). Exudate macromolecules were able to directly stabilize the BPNSs. The CCC values for exudate fractions >3 kDa (molecular weight >3 kDa) were over 129 times higher than that without exudates. It was proven that exudate protein was adsorbed onto the BPNSs, as promoted by Ca2+, and formed protein corona, which suppressed the attachment of BPNSs and conjunction with Ca2+ for particle growth. This study explored the inhibitory effect of ecological corona (eco-corona) on the aggregation of BPNSs in the crop root zone, and provides a crucial foundation for future studies on BP nanoparticles' interactions with organisms and potential sustainable agricultural applications. It is proposed that root exudates are an essential constituent of eco-corona, which require more attention in ultimate fate evaluation of nanoparticles.

The glycosylation process was investigated for the common brominated flame retardant tetrabromobisphenol A (TBBPA) in hydroponic exposure systems with pumpkin seedlings. Two typical glycosylation metabolites of TBBPA formed in pumpkin seedlings, TBBPA mono-β-d-glucopyranoside (TBBPA MG) and TBBPA di-β-d-glucopyranoside (TBBPA DG), increasing their mass early in the exposure (reaching maximum masses of 608 ± 53 and 3806 ± 1570 pmol at 12 h, respectively) and then falling throughout exposure. These two metabolites were released from roots to rhizosphere solutions, where they also exhibited initial increases followed by decreasing trends (reaching maximum masses of 595 ± 272 pmol at 3 h and 77.1 ± 36.0 pmol at 6 h, respectively). However, a (pseudo)zero-order deglycosylation of TBBPA MG and TBBPA DG (during the first 1.5 h) back to TBBPA was unexpectedly detected in the hydroponic solutions containing pumpkin exudates and microorganisms. The function of microorganisms in the solutions was further investigated, revealing that the microorganisms were main contributors to deglycosylation. Plant detoxification through glycosylation and excretion, followed by deglycosylation of metabolites back to the toxic parent compound (TBBPA) in hydroponic solutions, provides new insight into the uptake, transformation, and environmental fate of TBBPA and its glycosylated metabolites in plant/microbial systems.

Occurrences of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in tree bark from four species were investigated. Species-dependent congener distribution patterns were firstly reported for perfluorocarboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs). The majority of PFSAs and PFCAs in Chinese red pine bark were C5–C7 PFSAs and perfluorohexanoic acid (PFHxA, containing six carbon atoms, C6), whereas perfluorobutanesulfonic acid (PFBS, C4) and longer chain congeners (PFCAs: C ≥ 7; PFSAs: C ≥ 8) took a larger proportion in the fissured bark from Canadian poplar, Chinese scholartree and weeping willow. The species-dependent congener profiles depended on the structures and chemical compositions of tree bark, as well as the translocation of PFASs within plants. Different tree bark characteristics caused different retention abilities for particle-bound and gaseous PFASs. Particle-bound PFASs retained in the rougher structures of fissured bark led to preferential retention of long chain congeners (the major fraction in the particle phase), while lipid-rich Chinese red pine bark retained more gaseous PFASs (mainly short chain congeners). Besides, the abundance of short chain PFASs in red pine bark was consistent with the chain length-dependent translocation behaviors of PFASs in various plants, suggesting that translocation of PFASs within plants to tree bark may be invovled.

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant in the world. Its biotic methylation products, tetrabromobisphenol A mono- and dimethyl ether (TBBPA MME and TBBPA DME, respectively), are frequently detected in the environment, but the importance of abiotic methylation reactions of TBBPA in the environment is not known. In this study, the methylation of TBBPA mediated by methyl iodide (CH(3)I), a ubiquitous compound in aqueous environments, was investigated in simulated waters in the laboratory. It was found that abiotic methylation occurred under both light and dark conditions and was strongly affected by the pH, temperature, and natural organic matter concentration of the water. Abiotic methylation was further verified in natural river water, and the yield of TBBPA MME mediated abiotically by CH(3)I was much greater than that of biotic methylation. According to our calculations and by comparison of the activation energies (E(a)) for the abiotic methylation of TBBPA and the other four typical phenolic contaminants and/or metabolites (bisphenol A, triclosan, 5-OH-BDE-47, and 4′-OH-CB-61) mediated by CH(3)I, those phenolic compounds all show great methylation potentials. The results indicate a new abiotic pathway for generating TBBPA MME and TBBPA DME from TBBPA, and they also confirm the potentials for abiotic methylation of other phenolic contaminants in aqueous environments.

For the most complex artificial chlorinated environmental contaminants, much less is known for medium-chain CPs than short-chain CPs. In this research, the spatial distributions of MCCPs and SCCPs in farmland soil and maize leaves near a CP production facility were found marginally influenced by seasonal winds. The levels of ∑MCCPs and ∑SCCPs were in the ranges of

The most environmentally abundant bromophenol congener, 2,4,6-tribromophenol (2,4,6-TBP, 6.06 μmol/L), was exposed to rice for 5 d both in vivo (intact seedling) and in vitro (suspension cell) to systematically characterize the fate of its sulfation and glycosylation conjugates in rice. The 2,4,6-TBP was rapidly transformed to produce 6 [rice cells (3 h)] and 8 [rice seedlings (24 h)] sulfated and glycosylated conjugates. The predominant sulfation conjugate (TP(408), 93.0–96.7%) and glycosylation conjugate (TP(490), 77.1–90.2%) were excreted into the hydroponic solution after their formation in rice roots. However, the sulfation and glycosylation conjugates presented different translocation and compartmentalization behaviors during the subsequent Phase III metabolism. Specifically, the sulfated conjugate could be vertically transported into the leaf sheath and leaf, while the glycosylation conjugates were sequestered in cell vacuoles and walls, which resulted in exclusive compartmentalization within the rice roots. These results showed the micromechanisms of the different compartmentalization behaviors of 2,4,6-TBP conjugates in Phase III metabolism. Glycosylation and sulfation of the phenolic hydroxyl groups orchestrated by plant excretion and Phase III metabolism may reduce the accumulation of 2,4,6-TBP and its conjugates in rice plants.

Short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) are mixtures of complex chemical compounds with intensive usage. They are frequently detected in various environmental samples. However, the interaction between CPs and plants, especially the biotransformation behaviors of CPs within plants, is poorly understood. In this study, 1,2,5,6,9,10-hexachlorodecane (CP-4, a typical standard of individual SCCP congeners) and 52%-MCCP (a commercial mixture standard of MCCPs with 52% chlorine content by mass) were selected as representative chemicals to explore the metabolic behaviors of SCCPs and MCCPs using suspension rice cell culture exposure systems. Both 79.53% and 40.70% of CP-4 and 52%-MCCP were metabolized by suspension rice cells, respectively. A complementary suspected screening strategy based on the pair mass distances (PMD) analysis algorithm was used to study the metabolism of CPs mediated by the plant cells. Forty and 25 metabolic products for CP-4 and 52%-MCCP, respectively, were identified, including (multi-) hydroxylation, dechlorination, -HCl- elimination metabolites, (hydroxylation-) sulfation, and glycosylation conjugates. Here, we propose a comprehensive metabolic molecular network and provide insight on degradation pathways of SCCPs and MCCPs in plants for the first time, aiding in further understanding of the transformation behaviors of CPs.

Synthetic phenolic antioxidants (SPAs) are widely used in foodstuffs, cosmetics, plastics, and rubber products. Little is known about their spatiotemporal distribution in the marine environment. In this study, a total of 144 surface sediments and three sediment cores were collected from the coastal areas of northern China to determine the spatial and vertical distributions of SPAs. For surface sediments, the total concentrations of five SPAs and their four metabolites (∑

As the metabolites of tetrabromobisphenol A (TBBPA), tetrabromobisphenol A mono- and di-methyl ethers (TBBPA MME and TBBPA DME) have been detected in various environmental media. However, knowledge of the contribution of plants to their environmental fates, especially to the interactions between TBBPA DME and TBBPA, is quite limited. In this study, the metabolism and behaviors of TBBPA DME was studied with pumpkin plants through 15-day hydroponic exposure. The TBBPA were also studied separately using in-lab hydroponic exposure for comparison. The results showed that more TBBPA DME accumulated in pumpkin roots and translocated up to stems and leaves compared with TBBPA. Transformation of TBBPA DME occurred later and more slowly than that of TBBPA. Interconversion between TBBPA DME and TBBPA was verified in intact plants for the first time. Namely, TBBPA DME can be biotransformed to TBBPA MME (transformation ratio in mole mass, TRMM 0.50%) and to TBBPA (TRMM 0.53%) within pumpkin; and TBBPA can be biotransformed to TBBPA MME (TRMM 0.58%) and to TBBPA DME (TRMM 0.62%). In addition, two single benzene-ring metabolites, 2,6-dibromo-4-(2-(2-hydroxyl)-propyl)-anisole (DBHPA, TRMM 3.4%) with an O-methyl group and 2,6-dibromo-4-(2-(2-hydroxyl)-propyl)-phenetole (DBHPP, TRMM 0.57%) with an O-ethyl group, were identified as the transformation products in the TBBPA exposure experiments. The transformation and interconversion from TBBPA DME back to TBBPA is reported as a new pathway and potential source for TBBPA in the environment.

The fates, especially the phase I, phase II, and phase III metabolisms of typical halogenated organic pollutants in plants are attracting more and more research interests. A series of reactions and pathways are involved in metabolism of halogenated organic pollutants in plants, including dehalogenation, hydroxylation, methylation, combination with glucose (or glycoside), glutathione, and other groups, and final generation of the water-soluble, less toxic, and non-reactive substances. This article reviewed the metabolism of several typical organic halogenated pollutants and the role of related enzymes in plants. The prospect for the future was also proposed.

Polychloro-1,3-butadienes (polyCBDs) are attracting increasing concern due to their high toxicity. However, research on multiple polyCBDs in aquatic biota is still extremely limited. In this study, a sensitive method for simultaneous determination of nine polyCBD (Cl4–Cl6) congeners, including six tetrachlorobutadiene (TeCBD) isomers, two pentachlorobutadiene (PeCBD) isomers, and hexachlorobutadiene (HCBD), in shellfish was developed based on accelerated solvent extraction (ASE), solid-phase extraction (SPE) clean-up and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Low method limits of detection (MDLs) in the range 0.03–0.21 ng/g dry weight for target analytes with satisfactory recoveries (47.7 %–70.6 %) were achieved. The valid method was then applied to analyze nine polyCBDs congeners in 42 shellfish and 11 fish samples collected from markets in eight coastal cities, China. Trace HCBD was detected in 14 samples, while TeCBDs and PeCBDs were under the MDLs in all the samples, indicating little contamination of these pollutants in the marketed shellfish and fish in China. Multiple polyCBDs especially TeCBDs and PeCBDs were firstly involved in the proposed method and investigation here, which lay the groundwork for future research on the environmental behavior and exposure risks of polyCBDs in aquatic biotas.

Short chain chlorinated paraffins (SCCPs) are ubiquitously present as persistent organic pollutants in the environment. However, little information on the interaction of SCCPs with plants is currently available. In this work, young pumpkin plants (Cucurbita maxima × C. Moschata) were hydroponically exposed to the congener of chlorinated decane, 1,2,5,5,6,9,10-heptachlorodecane (1,2,5,5,6,9,10-HepCD), to investigate the uptake, translocation and transformation of chlorinated decanes in the intact plants. It was found that parent HepCD was taken up by the pumpkin roots, translocated from root to shoots, and phytovolatilized from pumpkin plants to air via the plant transpiration flux. Our data suggested that dechlorination of 1,2,5,5,6,9,10-HepCD to lower chlorinated decanes and rearrangement of chlorine atoms in the molecule were all mediated by the whole pumpkin seedlings. Chlorinated decanes were found in the shoots and roots of blank controls, indicating that chlorinated decanes in the air could be absorbed by leaves and translocated from shoots to roots. Lower chlorinated congeners (C10H17Cl5) tended to detain in air compared to higher chlorinated congeners (C10H16Cl6 and other C10H15Cl7). Potential transformation pathway and behavior of 1,2,5,5,6,9,10-HepCD in pumpkin were proposed based on these experiments.

In view of the final destination of nanomaterials, the water system would be an important sink. However, the environmental behavior of nanomaterials is rather confusing due to the complexity of the real environment. In this study, a freshwater ecosystem, including water, sediment, water lettuce, water silk, Asian clams, snails, water fleas, Japanese medaka, and Yamato shrimp, was constructed to study the distribution, bioaccumulation, and potential impacts of CeO2 nanoparticles (CeO2 NPs) via long-term exposure. The results demonstrated most of the CeO2 NPs deposited in the sediment (88.7%) when the partition approached to the constant 30 days later. The bioaccumulated Ce in six tested biota species was negatively correlated with its trophic level, showing no biomagnification of CeO2 NPs through this food web. CeO2 NP exposure induced visual abnormalities in hydrophytes, including chlorophyll loss in water silk and water lettuce, ultrastructural changes in pyrenoids of water silk, and root elongation in w...

The uncertainties in analysis of trace environmental pollutants may come from sample matrix and sample pretreatment process. In this study, a boundary model was developed based on the visualized data of mass spectrometry to evaluate the influences from sample matrix and pretreatment process. The factors affecting the pretreatment procedures, such as the solvents, the extraction sorbents and the extraction process had limited influences compared with matrix effects. Using such boundary model, we found that selecting suitable qualitative and quantitative ions for MS detector is more important for reducing the matrix effect in GC-MS analysis than the traditionally used methods of optimizing the pretreatment process since some clean up sorbents might be useless to reduce the matrix effects. As for 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), the fragmental ions were usually used for qualitative and quantitative analysis, which however was easily affected by the matrix effects. While, molecular ions would eliminate the influences from the sample matrix. Such a model could be used to decrease the uncertainty and increase the accuracy of environmental trace analysis.

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant (BFR), and it bioaccumulates throughout the food chains. Its fate in the first trophic level, plants, is of special interest. In this study, a four-day hydroponic exposure of TBBPA at a concentration of 1 μmol L(−1) to pumpkin seedlings was conducted. A nontarget screening method for hydrophilic bromine-containing metabolites was modified, based on both typical isotope patterns of bromine and mass defect, and used to process mass spectra data. A total of 20 glycosylation and malonyl glycosylation metabolites were found for TBBPA in the pumpkin plants. Representative glycosyl TBBPA reference standards were synthesized to evaluate the contribution of this glycosylation process. Approximately 86% of parent TBBPA was metabolized to form those 20 glycosyl TBBPAs, showing that glycosylation was the most dominant metabolism pathway for TBBPA in pumpkin at the tested exposure concentration.

Short chain chlorinated paraffins (SCCPs) are a group of complex emerging persistent organic pollutants. In this study, the uptake, translocation, and transformation of four constitutionally defined SCCP isomers were studied using whole pumpkin (Cucurbita maxima × C. moschata) and soybean (Glycine max L. Merrill) seedlings via hydroponic exposure. Results showed that the daughter SCCPs were C(10)Cl(5–8) and C(11–13)Cl(5–6). The metabolic transformation of all tested isomers included dechlorination and chlorine rearrangement. In addition, carbon chain decomposition products were found for isomers with trichlorinated carbon atoms (CCl(3)-groups) in both pumpkin and soybean seedlings. This study provides the first evidence of carbon chain decomposition of SCCPs in whole plants, and it suggests new metabolism pathways of SCCPs in the environment. The influence of carbon chain length and degree of chlorination of SCCPs on their fate and behavior within different plant species were also investigated. Bioaccumulation of SCCPs in pumpkin and soybean increased with increasing carbon chain length and degree of chlorination. In comparison, soybean translocated and degraded parent SCCPs faster and to a greater extent than pumpkin, but pumpkin accumulated parent SCCPs to a greater extent than soybean. After 10 days exposure, less than 4% of the initial mass of exposed chemicals remained in solution of exposure groups. The parent chemicals accumulated in roots ranging from 23.6% to 59.9% for pumpkin and 1.98% to 54.5% for soybean and in stems ranging from 0.7% to 3.81% for pumpkin and 0.50% to 2.54% for soybean. These results give new perspectives on the transport, transformation, and fate of SCCPs in the environment.

Synthetic phenolic antioxidants (SPAs) are a group of chemicals widely used in various daily necessities and industrial supplies. Little is known about the occurrence and bioaccumulation potential of SPAs in marine biota. In this study, five commonly used SPAs and their four metabolites were detected in mollusk samples ( n = 274) collected from the Chinese Bohai Sea during 2006-2016 and the spatiotemporal distribution and bioaccumulation of SPAs in mollusks were examined. The concentrations of 2,6-di- tert-butyl-4-hydroxytoluene (BHT) ranged from 383 to 501000 ng/g (geometric mean: 3450 ng/g), accounting for 79.4% of the total concentrations of SPAs and their metabolites (∑9SPAs). The mollusk species, Rapana venosa (RAP), contained higher levels of BHT than other species, suggesting that Rap could be used as a potential bioindicator for monitoring of the BHT pollution in the investigated region. The ∑9SPAs concentrations in mollusks gradually increased with years and a significant positive correlation ( r = 0.900, p < 0.05) was found between ∑9SPAs concentration and trophic level of the mollusks. The trophic magnification factor value of ∑9SPAs was calculated as 16.1, suggesting a high biomagnification potential of SPAs in mollusks in the Chinese Bohai Sea. The estimated daily intake of ∑9SPAs through dietary ingestion of mollusks was up to 602 and 789 ng/kg bw/day for adults and children and teenagers, respectively. The principal component analysis result suggests that there exists a common source for three gallates (OG, DG, and PG), and BHT metabolites in mollusks were mainly derived from degradation of BHT. This is the first study to report the occurrence and bioaccumulation potentials of SPAs and their metabolites in invertebrate species from coastal marine environments.

Hexachlorobutadiene (HCBD) has been listed as a persistent organic pollutant (POP) in the Stockholm Convention, and is now drawing more and more research interest. However, the understanding of its bioaccumulation, especially in plants, is still very limited. In this work, the behavior of HCBD in aqueous solution and pumpkin seedlings was studied through in-lab hydroponic exposure experiments. It was found that 69% of HCBD volatilized from water to the atmosphere after one day of exposure, and only 1% remained in the solution after four days. This high volatility might be the main cause of the low HCBD levels in aqueous environments. Although a great amount of HCBD volatilized into the atmosphere, only a small proportion of airborne HCBD was captured by the leaves and stems of the blank pumpkin seedling controls. The translocation of HCBD from the leaves to the bottom roots, as well as its release from the roots into the water, was detected. For the exposure groups, the pumpkin seedlings absorbed HCBD from both the hydroponic solution and the air via the roots and leaves, respectively. The concentration of HCBD in the exposed pumpkin roots linearly increased with the continuous addition of HCBD into the exposure system. Upward translocation from the roots to the leaves and downward translocation from the leaves to the roots existed simultaneously in the exposed pumpkin seedlings. However, the concentrations of HCBD in the leaves, stems and roots in the exposure group were much higher than those of the blank plant controls, suggesting little contribution from the airborne HCBD in the hydroponically exposed pumpkin seedlings. The lipid content did not show obvious effects on the bioaccumulation and biodistribution of HCBD in the pumpkin seedlings, indicating that the translocation of HCBD within the pumpkin seedlings might be an active process. This study provided new findings on the environmental behavior of HCBD, which will be helpful for understanding the exposure risks.

In view of the final destination of nanomaterials, the water system would be an important sink. However, the environmental behavior of nanomaterials is rather confusing due to the complexity of the real environment. In this study, a freshwater ecosystem, including water, sediment, water lettuce, water silk, Asian clams, snails, water fleas, Japanese medaka, and Yamato shrimp, was constructed to study the distribution, bioaccumulation, and potential impacts of CeO

Diode side pumped and acousto-optical (AO) Q-switched Tm, Ho, LuLiF laser at 2 μm wavelength obtained in a ring resonator is reported in this paper. The three LDAs were placed 120° apart around the laser rod of ∅4 × 20 mm dimension. A ring resonator has been used for its At free run mode, four different output loss ouplers has been tried. When the output loss is 20%, 103 mJ per pulse at 1 Hz pulse repetition frequency has been obtained with the optical to optical energy conversion efficiency of 3.17%. At the Q-switched mode, the laser pulse energy is 30 mJ with the pulse width of 417 ns. The optical to optical energy conversion efficiency is 0.93%. The slope efficiency is 6.36 and 2.90% under the two running mode, respectively.