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1.
Artigo em Inglês | MEDLINE | ID: mdl-34638113

RESUMO

The nitrogen-rich compounds are promising candidates for high-energy-density applications, owing to the large difference in the bonding energy between triple and single/double nitrogen bonds. The exploration of stable copper-nitrogen (Cu-N) compounds with high-energy-density has been challenging for a long time. Recently, through a combination of high temperatures and pressures, a new copper diazenide compound (P63/mmc-CuN2) has been synthesized [J. Phys. Chem. Lett. 2019, 10, 1109-1114]. But the pressure-composition phase diagram of Cu-N compounds at different temperatures is still highly unclear. Here, by combining first-principles calculations with crystal structure prediction method, the Cu-N compounds with different stoichiometric ratios were searched within the pressure range of 0-150 GPa. Four Cu-N compounds are predicted to be thermodynamically stable at high pressures, Pnnm-CuN2, two CuN3 compounds with the P-1 space group (named as I-CuN3 and II-CuN3) and P21/m-CuN5 containing cyclo-N5-. Finite temperature effects (vibrational energies) play a key role in stabilizing experimentally synthesized P63/mmc-CuN2 at ~55 GPa, compared to our predicted Pnnm-CuN2. These new Cu-N compounds show great promise for potential applications as high-energy-density materials with the energy densities of 1.57-2.74 kJ/g.

2.
Food Chem ; 370: 130901, 2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34500289

RESUMO

The development of Aspergillus niger (A. niger) spores as glucose oxidase (GOD) biocatalysts to produce gluconic acid is highly anticipated in the food industry. Herein, a piezoelectric sensor (PIS) method has been developed for the detection of GOD activity and better application of rapid screening of GOD activity in A. niger spores. The GOD activity detection is based on GOD catalyzing ß-d-glucose to produce gluconic acid, which results in frequency shift changes recorded by the PIS device in real-time. Using the PIS method, the kinetic parameter 6.5 mg/mL, the correlation equation υ0=31.92CGOD+1.04, the recoveries (89.4%-93.9%, and their RSDs were all within 6.1%) and the optimal GOD activity in A. niger spores under different treatment conditions was obtained. Compared with the classical methods, the proposed method is accurate, rapid, convenient and does not require additional reagents. It has a broad range of potential applications for exploring new GOD biocatalysts.

3.
Food Chem ; 370: 131082, 2021 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-34537435

RESUMO

In this study, chitosan (CH), mulberry anthocyanin (MA), and lemongrass essential oils (LEO) were used as an interlayer using a 3D printer. Further, cassava starch (CS) was used as a protective layer to form indicator films. The indicator films containing LEO showed significant antioxidant and antibacterial properties, and the release rate of LEO increased with a rise in pH. When chilled pork spoiled, the color of the indicator films changed from red to gray-blue, and the RGB values could be automatically analyzed by a smartphone application to determine pork freshness. These films hold implications as easy-to-use indicators of meat freshness, with great potential for monitoring food spoilage, as part of an intelligent packaging system.

4.
Sci Total Environ ; 803: 150036, 2021 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-34525718

RESUMO

Thallium (Tl) is a highly toxic trace metal. Lead (Pb)­zinc (Zn) smelting, which is a pillar industry in various countries, is regarded as one of the dominant anthropogenic sources of Tl contamination in the environment. In this study, thallium isotope data have been evaluated for raw material and a set of industrial wastes produced at different stages of Pb-Zn smelting in a representative large facility located by the North River, South China, in order to capture Tl isotope signatures of such typical anthropogenic origin for laying the foundation of tracking Tl pollution. Large variations in Tl isotopic compositions of raw Pb-Zn ores and solid smelting wastes produced along the process chain were observed. The ε205Tl values of raw Pb-Zn ores and return fines are -0.87 ± 0.26 and -1.0 ± 0.17, respectively, contrasted by increasingly more negative values for electrostatic precipitator dust (ε205Tl = -2.03 ± 0.14), lime neutralizing slag (ε205Tl = -2.36 ± 0.18), and acid sludge (ε205Tl = -4.62 ± 0.76). The heaviest ε205Tl (1.12 ± 0.51) was found in clinker. These results show that isotopic fractionation occurs during the smelting processes. Obviously, the lighter Tl isotope is enriched in the vapor phase (-3.75 ε205Tl units). Further XPS and STEM-EDS analyses show that Tl isotope fractionation conforms to the Rayleigh fractionation model, and adsorption of 205Tl onto hematite (Fe2O3) may play an important role in the enrichment of the heavier Tl isotope. The findings demonstrate that Tl isotope analysis is a robust tool to aid our understanding of Tl behavior in smelting processes and to provide a basis for source apportionment of Tl contaminations.

5.
Nat Commun ; 12(1): 5072, 2021 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-34417473

RESUMO

In vivo bioprinting has recently emerged as a direct fabrication technique to create artificial tissues and medical devices on target sites within the body, enabling advanced clinical strategies. However, existing in vivo bioprinting methods are often limited to applications near the skin or require open surgery for printing on internal organs. Here, we report a ferromagnetic soft catheter robot (FSCR) system capable of in situ computer-controlled bioprinting in a minimally invasive manner based on magnetic actuation. The FSCR is designed by dispersing ferromagnetic particles in a fiber-reinforced polymer matrix. This design results in stable ink extrusion and allows for printing various materials with different rheological properties and functionalities. A superimposed magnetic field drives the FSCR to achieve digitally controlled printing with high accuracy. We demonstrate printing multiple patterns on planar surfaces, and considering the non-planar surface of natural organs, we then develop an in situ printing strategy for curved surfaces and demonstrate minimally invasive in vivo bioprinting of hydrogels in a rat model. Our catheter robot will permit intelligent and minimally invasive bio-fabrication.


Assuntos
Bioimpressão , Cateteres , Imãs/química , Robótica , Animais , Linhagem Celular , Elasticidade , Condutividade Elétrica , Humanos , Hidrogéis/química , Fígado/diagnóstico por imagem , Ratos Sprague-Dawley , Suínos , Tomografia Computadorizada por Raios X , Viscosidade
6.
J Mater Chem B ; 9(29): 5887-5897, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34259303

RESUMO

As one of the serious complications of diabetes, diabetic ulcers induce several clinical problems. Although a variety of wound dressings are commonly employed, their role is too simple to integrate wound adaptation, therapeutics and effectiveness. To meet this comprehensive need, an injectable hydrogel (Col/APG) consisting of collagen and polyethylene glycol was prepared and loaded with umbilical cord stem cell factor (SCF) for the treatment of diabetic wounds. The physico-chemical properties of the Col/APG hydrogel, including rheology, self-shaping and self-healing, were demonstrated to adapt to the wound. After loading with the SCF, the adhesion strength of the resulting Col/APG + SCF hydrogel was enhanced to 17 kPa and it also showed favorable biocompatibility. A rapid cellular response, sufficient collagen deposition and marked neovascularization were observed in the whole cortex defect model of a diabetic rat after the Col/APG + SCF hydrogel was applied. Additionally, the skew toward M2 macrophages, credited with providing the anti-inflammatory function, also existed in both hydrogel groups. These findings suggested that the Col/APG hydrogel is a desirable scaffold and the Col/APG hydrogel loaded stem cell factor as a dressing is a promising treatment for diabetic tissue regeneration.

7.
J Insect Sci ; 21(2)2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33844017

RESUMO

The codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) is a destructive pest of apple (Malus domestica (Rosales: Rosaceae)), pear (Pyrus spp. (Rosales: Rosaceae)), and other pome tree fruits; outbreaks cause significant ecological and economic losses. In this study, we used CLIMEX model to predict and evaluate the global risk of C. pomonella based on historical climate data (1989-2018) and simulated future climate data (2071-2100) under the RCP4.5 scenarios. Cydia pomonella exhibited a wide distribution under both historical and future climate conditions. Climate change is predicted to expand the northern boundary of the potential distribution from approximately 60°N to 75°N. Temperature was the most dominant factor in climatic suitability for the pest. Combinations of multiple meteorological factors (relative humidity and precipitation) associated with a failure to break diapause in certain regions also affect suitability, particularly in northern South America and central Africa. Irrigation only had a slight impact on species favorability in some areas. The projections established in our study present insight into the global potential suitability of C. pomonella under climate change scenarios by the end of the 21st century. Farmers should be aware of the risk associated with the pest based on the results, which would provide guidance for quarantine agencies and trade negotiators worldwide.


Assuntos
Mudança Climática , Modelos Estatísticos , Mariposas , Dinâmica Populacional , Animais , Clima , Produtos Agrícolas/economia , Diapausa , Análise Fatorial , Frutas , Aquecimento Global , Malus , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Controle de Pragas , Pyrus , Temperatura , Árvores
8.
Int J Biol Macromol ; 177: 135-148, 2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33610604

RESUMO

Polylactic acid (PLA)/nano-TiO2(TiO2 NPs)/Graphene oxide (GO) nano-fibrous films were prepared by ultrasonic assisted electrostatic spinning technology, and the effects of TiO2 NPs:GO mass ratio and ultrasonic power on film morphology and mechanical, thermal, barrier and antibacterial properties were investigated. The addition of TiO2 NPs and GO can significantly increase the tensile strength and elongation at the break of PLA nano-fibrous films, and improve the water barrier properties of the nano-fibrous films. The antibacterial experiment showed that the inhibition rates of the nano-fibrous films against Escherichia coli and Staphylococcus aureus after 24 h exposure to UV irradiation reached 94.4 ± 1.8% and 92.6 ± 1.7% At the same time, the fresh-keeping packaging experiment of green peppers at room temperature, through the determination of hardness, soluble solids, chlorophyll content to determine the degree of decay of green pepper, it showed that PLA/TiO2 NPs/GO nano-fibrous films can better maintain the sensory quality of green peppers, delay the rate of spoilage of green peppers, and prolong the preservation period of green peppers.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Capsicum/microbiologia , Grafite/química , Nanopartículas/química , Poliésteres/química , Titânio/química , Escherichia coli/efeitos dos fármacos , Conservação de Alimentos/métodos , Nanocompostos/química , Staphylococcus aureus/efeitos dos fármacos
9.
Nanotechnology ; 2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33571970

RESUMO

Ultrasmall metallic nanogaps are of great significance for wide applications in various nanodevices. However, it is challenging to fabricate ultrasmall metallic nanogaps by using common lithographic methods due to the limited resolution. In this work, we establish an effective approach for successful formation of ultrasmall metallic nanogaps based on the spontaneous nanoscale dewetting effect during metal deposition. By varying the initial opening size of the exposed resist template, the influence of dewetting behavior could be adjusted and tiny metallic nanogaps can be obtained. We demonstrate that this method is effective to fabricate diverse sub-10-nm gaps in silver nanostructures. Based on this fabrication concept, even sub-5-nm metallic gaps were obtained. SERS measurements were performed to show the molecular detection capability of the fabricated Ag nanogaps. This approach is a promising candidate for sub-10-nm metallic gaps fabrication, thus possessing potential applications in nanoelectronics, nanoplasmonics, and nano-optoelectronics.

10.
Environ Sci Process Impacts ; 23(1): 170-178, 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33399599

RESUMO

Hydroxypyromorphite (HPM) is a low-solubility Pb phosphate mineral that has the potential to limit solubility and bioavailability of Pb in soils and water. Because of reported uncertainty regarding the solubility product of this important mineral, we re-evaluated the solubility of Pb and activity of the free Pb2+ ion in aqueous suspensions of microcrystalline HPM equilibrated up to 30 days over a wide range of added soluble phosphate. A small addition of phosphate (0.1 mM) reduced Pb solubility as measured by ICP-OES, but greater phosphate additions (up to 50 mM) had no further effect in lowering HPM solubility. However, free Pb2+ ion activity measured by ion-selective electrode progressively decreased from about 10-6.5 with no added phosphate to 10-9 as soluble phosphate was increased. The effect of soluble phosphate in lowering Pb2+ activity is attributed to inhibited dissolution of HPM as well as increased Pb2+-phosphate ion pair formation in solution at higher solution concentrations of phosphate. Measurement of the ion activity products (IAP) of the solutions at equilibrium with HPM gave highly variable IAP values that were sensitive to pH and were generally not consistent with the reported solubility product of this mineral. The high variability of the IAPs for solutions with variable pH and phosphate concentrations indicates that dissolution-precipitation reactions of HPM are not described by a constant solubility product at equilibrium, possibly because of the incongruent dissolution behavior of this mineral at near-neutral pH.


Assuntos
Chumbo , Fosfatos , Concentração de Íons de Hidrogênio , Solubilidade , Água
11.
Environ Pollut ; 271: 116171, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33387783

RESUMO

In addition to being historically intentionally manufactured as commercial products, polychlorinated biphenyls (PCBs) can be unintentionally released as by-products from industrial processes. Recent studies have emphasized the importance of unintentionally produced PCBs (UP-PCBs) and have even identified them as major contributors to atmospheric PCBs. However, little is known about contributions of UP-PCBs in current soils. In this study, all 209 PCB congeners were analyzed in agricultural soils on a national scale to investigate the influence of unintentional sources on Chinese soil. The concentration of Σ209PCBs in soils across China was in the range of 64.3-4358 pg/g. Four non-Aroclor congeners, i.e., PCB11, PCB44 + 47+65, PCB68, and PCB209, were dominant among all PCBs, averagely accounting for 26.3%, 8.83%, 3.03%, and 2.80% of total PCBs, respectively. PCB11 and PCB209 were found to be higher in East China, while PCB44 + 47+65 and PCB68 were higher in South China. Their spatial distributions were largely dependent on local sources. The results of source apportionment indicated that the legacy of historically produced and used commercial PCB mixtures was the dominant contributor to seven indicator PCBs in Chinese agricultural soils, especially high-chlorinated congeners. However, unintentional sources (i.e., pigment/paint, combustion-related sources, and polymer sealant), which contributed 57.4% of the total PCBs, are controlling PCB burdens in agricultural soils across China.


Assuntos
Bifenilos Policlorados , Poluentes do Solo , Agricultura , China , Monitoramento Ambiental , Bifenilos Policlorados/análise , Solo , Poluentes do Solo/análise
12.
Jpn J Infect Dis ; 74(1): 54-60, 2021 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-32741931

RESUMO

This study aimed to analyze the clinical characteristics and potential predictors of disease severity in patients with coronavirus disease 2019 (COVID-19). We retrospectively analyzed the clinical data from 64 (37 male and 27 female) patients with COVID-19. Their mean age was 47.8 years; 43 (67.2%) cases were non-severe, 21 (32.8%) were severe, and 2 patients (3.1%) died. Age and serum ferritin levels were significantly associated with COVID-19 severity. There were no significant differences in the duration of severe illness or the number of days on high-level respiratory support between the low-dose and high-dose methylprednisolone groups. The mean number of days in hospital in the high-dose group was higher than that in the low-dose group. Repeated monitoring of ferritin, interleukin-6, C-reactive protein, lactic acid dehydrogenase, and erythrocyte sedimentation rate during COVID-19 treatment may assist in the prediction of disease severity and evaluation of treatment effects.


Assuntos
COVID-19/diagnóstico , COVID-19/patologia , SARS-CoV-2 , Índice de Gravidade de Doença , Adulto , Idoso , COVID-19/tratamento farmacológico , COVID-19/epidemiologia , China/epidemiologia , Feminino , Glucocorticoides/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco
13.
Bioorg Chem ; 106: 104511, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33272707

RESUMO

In this study, a novel series of 4,6,7-trisubstituted quinoline analogues bearing thiazolidinones were designed and synthesized based on our previous study. Among them, the most potent compound 15i, 4-((4-(4-(3-(2-(2,6-difluorophenyl)-4-oxothiazolidin-3-yl)ureido)-2-fluorophenoxy)-6-methoxyquinolin-7-yl)oxy)-N,N-diethylpiperidine-1-carboxamide was identified as a multi-kinase inhibitor. The results of MTT assay revealed in vitro antitumor activities against HT-29 cells of compound 15i with an IC50 value of 0.19 µM which was 14.5-fold more potent than that of Regorafenib. In the cellular context, significant antiproliferation, cytotoxicity and induction of apoptosis on HT-29 cells in a dose- and time-dependent manner were confirmed by IncuCyte live-cell imaging assays. Moreover, compound 15i strongly induced apoptosis by arresting cell cycle into the G2/M phase. No antiproliferation and cytotoxicity against human normal colorectal mucosa epithelial cell FHC was observed at 10.0 µg/mL or lower concentrations which indicated that the toxicity to normal cells of compound 15i was much lower than that of Regorafenib. Based on the above findings, further structural modification will be conducted for the development of more potent kinase inhibitors as anticancer agents.

14.
J Hazard Mater ; 407: 124402, 2021 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-33189469

RESUMO

Thallium (Tl) pollution caused by the exploitation of uranium (U) mines has long been neglected due to its low crustal abundance. However, Tl may be enriched in minerals of U ore because Tl has both sulfurophile and lithophile properties. Herein, a semi-dynamic leaching experiment combined with statistical analysis, geochemical speciation and multi-characterization provided novel insight into the distinct features and mechanisms of Tl release from uranium mill tailings (UMT). The results showed that particle size effects prevail over the pH on Tl release, and surface dissolution is the pivotal mechanism controlling Tl release based on Fick's diffusion model. The study revealed that long-term leaching and weathering can lead to the increased acid-extractable and oxidizable fractions of Tl in UMT, and that the exposure and dissolution of Tl-containing sulfides would largely enhance the flux of Tl release. The findings indicate that UMT containing (abundant) pyrite should be paid particular attention due to Tl exposure. Besides, critical concern over the potential Tl pollution in universal U mining and hydrometallurgical areas likewise may need to be seriously reconsidered.


Assuntos
Poluentes Radioativos do Solo , Urânio , Poluentes Radioativos da Água , Mineração , Tálio/análise , Urânio/análise , Poluentes Radioativos da Água/análise
15.
J Environ Manage ; 281: 111875, 2021 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-33378737

RESUMO

Alpine grasslands on the Qinghai-Tibetan Plateau are sensitive and vulnerable to climate change and human activities. Climate warming and overgrazing have already caused degradation in a large fraction of alpine grasslands on this plateau. However, it remains unclear how human activities (mainly livestock grazing) regulates vegetation dynamics under climate change. Here, alpine grassland productivity (substituted with the normalized difference vegetation index, NDVI) is hypothesized to vary in a nonlinear trajectory to follow climate fluctuations and human disturbances. With generalized additive mixed modelling (GAMM) and residual-trend (RESTREND) analysis together, both magnitude and direction of climatic (in terms of temperature, precipitation, and radiation) and anthropogenic impacts on NDVI variation were examined across alpine meadows, steppes, and desert-steppes on the Qinghai-Tibetan Plateau. The results revealed that accelerating warming and greening, respectively, took place in 76.2% and 78.8% of alpine grasslands on the Qinghai-Tibetan Plateau. The relative importance of temperature, precipitation, and radiation impacts was comparable, between 20.4% and 24.8%, and combined to explain 66.2% of NDVI variance at the pixel scale. The human influence was strengthening and weakening, respectively, in 15.5% and 14.3% of grassland pixels, being slightly larger than any sole climatic variable across the entire plateau. Anthropogenic and climatic factors can be in opposite ways to affect alpine grasslands, even within the same grassland type, likely regulated by plant community assembly and species functional traits. Therefore, the underlying mechanisms of how plant functional diversity regulates nonlinear ecosystem response to climatic and anthropogenic stresses should be carefully explored in the future.


Assuntos
Ecossistema , Pradaria , Animais , Mudança Climática , Humanos , Dinâmica não Linear , Tibet
16.
Comput Biol Chem ; 89: 107397, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33035753

RESUMO

Qiang-Huo-Sheng-Shi decoction (QHSSD), a classic traditional Chinese herbal formula, which has been reported to be effective in rheumatoid arthritis (RA) and osteoarthritis (OA). However, the concurrent targeting mechanism of how the aforementioned formula is valid in the two distinct diseases OA and RA, which represents the homotherapy-for-heteropathy principle in traditional Chinese medicine (TCM), have not yet been clarified. In the present study, network pharmacology was adopted to analyze the potential molecular mechanism, and therapeutic effective components of QHSSD on both OA and RA. A total of 153 active ingredients in QHSSD were identified, 142 of which associated with 59 potential targets for the two diseases were identified. By constructing the protein-protein interaction network and the compound-target-disease network, 72 compounds and 10 proteins were obtained as the hub targets of QHSSD against OA and RA. The hub genes of ESR1, PTGS2, PPARG, IL1B, TNF, MMP2, IL6, CYP3A4, MAPK8, and ALB were mainly involved in osteoclast differentiation, the NF-κB and TNF signaling pathways. Moreover, molecular docking results showed that the screened active compounds had a high affinity for the hub genes. This study provides new insight into the molecular mechanisms behind how QHSSD presents homotherapy-for-heteropathy therapeutic efficacy in both OA and RA. For the first time, a two-disease model was linked with a TCM formula using network pharmacology to identify the key active components and understand the common mechanisms of its multi-pathway regulation. This study will inspire more innovative and important studies on the modern research of TCM formulas.


Assuntos
Artrite Reumatoide/tratamento farmacológico , Medicamentos de Ervas Chinesas/farmacologia , Osteoartrite/tratamento farmacológico , Artrite Reumatoide/genética , Diferenciação Celular/efeitos dos fármacos , Bases de Dados de Produtos Farmacêuticos/estatística & dados numéricos , Medicamentos de Ervas Chinesas/metabolismo , Expressão Gênica/efeitos dos fármacos , Humanos , Simulação de Acoplamento Molecular , Osteoartrite/genética , Osteoclastos/citologia , Farmacologia/métodos , Mapas de Interação de Proteínas
17.
Prog Brain Res ; 253: 201-227, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32771124

RESUMO

While there has been a marked increase in investigation of benefits of sporting engagement and fitness beyond typical health benefits, particularly looking at beneficial effects on cognitive ability, there has been less investigation of whether cognitive training can benefit sporting-specific skills. Here, the effects of simple cognitive training on a sport-related skill were assessed, with the specific hypothesis that training on a visual tracking task would improve the ability of volleyball players to spike the ball on a volleyball court (the volleyball equivalent of a tennis smash). Following training with such a task, improvement in spiking performance was seen when the target was indicated before spike execution but not when it was indicated during execution. There was some retention of the spiking improvements 1 month after visual task training. No improvements were seen when a cognitive task with no motion was used for training such that the results suggest benefits of appropriate cognitive training on aspects of sporting skills. Future work could beneficially assess application to a more sporting environment, evaluate the suitability of different cognitive training, and see if effects are seen in individuals with higher sporting skill.


Assuntos
Desempenho Atlético/fisiologia , Prática Psicológica , Desempenho Psicomotor/fisiologia , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Voleibol/fisiologia , Adulto , Feminino , Humanos , Masculino , Percepção de Movimento/fisiologia , Adulto Jovem
18.
Inorg Chem ; 59(17): 11930-11934, 2020 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-32805992

RESUMO

A series of 3D homologous metal-organic frameworks, [M(H0.5L)2] [M = Dy (1), Ho (2), Yb (3), Sm (4), Gd (5), and Y (6); H2L = 5-(1H-imidazol-1-yl)isophthalic acid], were isolated. In these complexes, the metal centers behave as hexacoordinated environments with distorted octahedral geometries, which is unusual in the lanthanide series, linking to each other and producing a fascinating 3D architecture. Magnetically, 1 features a field-driven dual-magnetic relaxation, which is rarely observed in high-dimensional coordination polymers. Analysis on the dilution sample (1@Y) and ab initio calculation unveil that the thermally assisted slow relaxation is mostly caused by the single-ion magnetism of DyIII itself.

19.
ChemSusChem ; 13(17): 4394-4399, 2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32668064

RESUMO

Lignin may serve as a renewable feedstock for the production of chemicals and fuels if mild, scalable processes for its depolymerization can be devised. The use of small organic thiols represents a bioinspired strategy to cleave the ß-O-4 bond, the most common linkage in lignin. In the present study, synthetic ß-O-4 linked polymers were treated with organic thiols, yielding up to 90 % cleaved monomer products. Lignin extracted from poplar was also treated with organic thiols resulting in molecular weight reductions as high as 65 % (Mn ) in oxidized lignin. Thiol-based cleavage of other lignin linkages was also explored in small-molecule model systems to uncover additional potential pathways by which thiols might depolymerize lignin. The success of thiol-mediated cleavage on model dimers, polymers, and biomass-derived lignin illustrates the potential utility of small redox-active molecules to penetrate complex polymer matrices for depolymerization and subsequent valorization of lignin into fuels and chemicals.

20.
Sci Total Environ ; 742: 140321, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32721712

RESUMO

Metal(loid) contamination caused by industrial activities in agricultural soils has become a universal environmental and food safety concern. This study revealed the contamination, pathway, and source contribution of metal(loid)s such as lead (Pb), zinc (Zn) and cadmium (Cd) in maize and soils in different residential areas impacted by long-term historical artisanal zinc smelting activities from Southwest China. Results revealed that the soils were contaminated heavily by metals like Pb, Zn and Cd, with contents of 40-14,280, 150-47,020 and 1.28-61.7 mg/kg, respectively. Hazard quotients of food uptake for Pb, Cd and Cr in maize grains were extremely high for residents, in particular for the children. To trace the sources of metal health risk, lead isotope fingerprinting and binary mixing modeling were applied. It indicated that the anthropogenic activities contributed over 80% to the Pb contamination in maize grains. The findings highlighted warning levels of health risks to the residents in consuming maize grains in the historical artisanal PbZn smelting area. Therefore, an effective strategy including pollution source control and remediation measures must be taken to improve the soil quality and guarantee food safety around the historical smelting areas likewise.


Assuntos
Metais Pesados/análise , Poluentes do Solo/análise , Criança , China , Monitoramento Ambiental , Humanos , Isótopos , Chumbo , Medição de Risco , Solo , Zea mays , Zinco/análise
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