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1.
Artigo em Inglês | MEDLINE | ID: mdl-32086636

RESUMO

Pediatric porcines have widely been used as substitute for children in biomechanical research. Previous studies have used entire piglet cranium when testing their properties. Here, the piglet craniums from the frontal and parietal locations were carefully dissected into spongy and cortical part, and tensile tests at different strain rates were then conducted on these two bone types. It is found that the elastic modulus, yield stress, and ultimate stress of the cortical bone were all significantly higher than those of the spongy bone. The ultimate strains of the cortical and spongy bone were similar. Overall, the effect of the position on the mechanical properties did not reach significance. Cortical bone strength from the frontal location was slightly higher than that obtained from the parietal location; however, spongy bone did not show this location difference. The mechanical properties of both the cortical and spongy bone are significantly strain-rate dependent. Specifically, the elastic modulus, yield stress, and the ultimate stress of the cortical bone increased by approximately 123%, 63%, and 50%, respectively, with strain rates ranging from 0.001 to 10/s. For spongy bone, increases were approximately 128%, 73%, and 77%, respectively. Ultimate strain decreased by approximately 37% and 7% for cortical and spongy bone, respectively. An elastic-plastic constitutive model incorporating with strain rate based on a combined exponential and logarithmic function was proposed and implemented into LS-DYNA through user-defined material. The developed model and the subroutine code successfully simulated the strain-rate characteristics and the fracture process of the bone samples.

2.
Sci Rep ; 10(1): 1598, 2020 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-32005910

RESUMO

Based on the electrical characteristic detection technology, the quantitative prediction models of sensory score and physical and chemical quality Index (theaflavins, thearubigins, and theabrownins) were established by using the fermented products of Congou black tea as the research object. The variation law of electrical parameters during the process of fermentation and the effects of different standardized pretreatment methods and variable optimization methods on the models were discussed. The results showed that the electrical parameters vary regularly with the test frequency and fermentation time, and the substances that hinder the charge transfer increase gradually during the fermentation process. The Zero-mean normalization (Zscore) preprocessing method had the best noise reduction effect, and the prediction set correlation coefficient (Rp) value of the original data could be increased from 0.172 to 0.842. The mixed variable optimization method (MCUVE-CARS) of Monte Carlo uninformed variable elimination (MC UVE) and competitive adaptive reweighted sampling (CARS) was proved that the characteristic electrical parameters were the loss factor (D) and reactance (X) of the low range. Based on the characteristic variables screened by MCUVE-CARS, the quantitative prediction models for each fermentation quality indicator were established. The Rp values of the sensory score, theaflavin, thearubigin and theabrownins of the predicted models were 0.924, 0.811, 0.85 and 0.938 respectively. The relative percent deviation (RPD) values of the sensory score, theaflavins, thearubigins and theabrownins of the predicted models were 2.593, 1.517, 1,851 and 2.920 respectively, and it showed that these models have good performance and could realize quantitative characterization of key fermentation quality indexes.

3.
Artigo em Inglês | MEDLINE | ID: mdl-31897871

RESUMO

This paper systematically studied the mass concentration levels of PM2.5 and PM10 and obtained the morphological characteristics and components of the particles through scanning electron microscopy (SEM-EDX) and discussed the sources of the particles. Meanwhile, the health risk was evaluated according to the mass concentration of particulate matter. The results showed that the average annual PM2.5 and PM10 in the eastern part of Chengdu were 101.99 µg/m3 and 168.89 µg/m3, respectively, exceeding the national second-level average annual air quality standard (GB3095-2012). Both of them were the highest in winter and the lowest in summer and had a significant positive correlation. The atmospheric particles in the study area were mainly composed of fly ash particles, soot aggregates, mineral particles (sulfate mineral particles, carbonate mineral particles, etc.), which mainly came from coal burning, dust, automobile exhaust and secondary products. The results of the health risk assessment showed that the mass concentration of PM2.5 and PM10 in the atmosphere of the eastern part of Chengdu exceeded the IT-1 target. The average annual air quality index was 185.84, and the air quality index was level 4, classified as medium pollution. PM10 and PM2.5 were both excessive pollutants, and PM10 was the primary pollutant. Relevant measures should be taken to control particulate matter sources to some extent.

4.
Development ; 147(4)2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31988189

RESUMO

Cellular proliferation is a basic process during organ development, tissue homeostasis and disease progression. Likewise, after injury typically multiple cell lineages respond to various cues and proliferate to initiate repair and/or remodeling of the injured tissue. Unravelling the specific role of proliferation of one cell type and its lineage in the context of the whole organism during tissue regeneration and/or disease progression would provide valuable information on these processes. Here, we report a new genetic system that allows cell proliferation to be inhibited in a tissue-specific manner. We generated Cre- or Dre-inducible p21-GFP (ip21-GFP) transgenic mice that enable experimentally induced permanent cell cycle arrest of specific cell lineages of interest, while genetically marking these cells. This system allows for the inhibition of pathogenic cell proliferation. We found that cardiac fibroblast proliferation inhibition significantly reduced scar formation, and promoted neovascularization and cardiomyocyte survival. Additionally, we found that inhibition of one type of cell proliferation (namely, hepatocytes) induces the lineage conversion of another type cells (i.e. ductal cells) during tissue regeneration. These results validate the use of ip21-GFP mice as a new genetic tool for cell lineage-specific inhibition of cell proliferation in vivo.

5.
J Reprod Dev ; 66(1): 57-65, 2020 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-31801914

RESUMO

Testis-specific genes are prone to affect spermatogenesis or sperm fertility, and thus may play pivotal roles in male reproduction. However, whether a gene really affects male reproduction in vivo needs to be confirmed using a gene knock-out (KO) model, a 'gold standard' method. Increasing studies have found that some of the evolutionarily conserved testis-enriched genes are not essential for male fertility. In this study, we report that 1700121C10Rik, a previously uncharacterized gene, is specifically expressed in the testis and produces two long noncoding RNAs (lncRNAs) in mouse: Transcript 1 and Transcript 2. qRT-PCR, northern blotting, and in situ hybridization revealed that expression of both the lncRNAs commenced at the onset of sexual maturity and was predominant in round and elongating spermatids during spermiogenesis. Moreover, we found different subcellular localization of Transcript 1 and Transcript 2 that was predominant in the cytoplasm and nucleus, respectively. 1700121C10Rik-KO mouse model disrupting Transcript 1 and Transcript 2 expression was generated by CRISPR/Cas9 to determine their role in male reproduction. Results showed that 1700121C10Rik-KO male mice were fully fertile with approximately standard testis size, testicular histology, sperm production, sperm morphology, sperm motility, and induction of acrosome reaction. Thus, we conclude that both the testis-specific 1700121C10Rik-produced lncRNAs are dispensable for male fertility in mice under standard laboratory conditions.

6.
Biomaterials ; 230: 119650, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31806404

RESUMO

A multitude of micro- and nano-surface structures have been developed to improve the clinical performance of endosseous titanium (Ti) implants. However, most of these surface structures only simulate the topographic elements on a micro- or nano-scale. In this study, a nano-micro hierarchical TiO2 clustered nanotubular structure was fabricated using anodization, and then functionalized with platelet derived growth factor-BB (PDGF-BB) using PhoA (11-hydroxyundecylphosphonic acid)/CDI (carbonyldiimidazole) chemistry. The resulting 3-dimensional spatial biomimetic structure, named NTPCP, exhibited negligible cytotoxicity and satisfactory bio-activity for host cells, and significantly enhanced the attachment as well as osteogenesis-related functions (early-stage proliferation, extracellular matrix synthesis and mineralization) of human bone marrow mesenchymal stem cells (bMSCs). We observed drastically elevated expression of osteocalcin (OCN), which mirrored prominent bone formation around the NTPCP implants in a rat model. This study establishes a novel strategy to improve the osseointegration of endosseous Ti implants via surface nano-topographic modification and bio-factor covalent functionalization.

7.
J Hazard Mater ; 385: 121528, 2020 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-31735468

RESUMO

Concentrations of Pb and Cd in topsoil from 24 locations along the Baguan River near a smelting dump in west Panzhihua were measured using ICP-MS to examine the spatial distributions of these toxic heavy metals. Twenty-one profile samples, 7 from each of 3 locations down to 80 cm, were also analyzed to establish background levels and Pb - Cd correlations. Lead isotopic ratios in all 45 samples and potential sources of soil contamination were determined using MC-ICP-MS. Contamination levels of Pb and Cd in soils from both sides of the river ranged from low to moderate, and the concentrations of Pb and Cd exhibited highly correlated behavior. Results of an isotope-tracer technique determined the number of end-member contaminants and background compositions contributing to the compositions of topsoils. Results of a binary mixing model indicated that contaminants in upslope soils from relatively higher elevations were coal and derivative products, and that these soils are isotopically distinct from downslope soils. Contaminants in downslope soils were slag and derivative products from V processing. Results demonstrate the use of Pb isotopic tracers in low-to-moderate contaminant levels to predict potential sources and Pb is a viable surrogate to trace potential Cd contamination in Panzhihua region.

8.
Clin Nutr ; 39(1): 192-197, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30718095

RESUMO

BACKGROUND & AIMS: Type 2 diabetes (T2D) is a complex metabolic disease with numerous risk factors, including a growing number of genetic susceptibility variants. The TCF7L2 gene is closely associated with an increased risk of type 2 diabetes, but the association of TCF7L2 with weight-related traits in humans is unclear. The purpose of this study was to determine if TCF7L2 variants and body mass index/waist circumference (BMI/WC) act synergistically to influence the incidence of type 2 diabetes in a Chinese population. METHODS: This is a large sample, case-control study. We recruited 1842 Chinese type 2 diabetes patients and 7777 healthy controls and collected demographic and anthropometric characteristics and blood samples. We extracted DNA and genotyped the TCF7L2 single nucleotide polymorphisms rs7903146 and rs290487 in all participants. RESULTS: There were significant linear interactions between rs7903146 and BMI/WC and elevated blood glucose (P < 0.001); rs290487 and BMI/WC also showed a linear interaction with blood glucose levels (P < 0.001). The interaction was stronger at higher BMI (>21.02) and higher WC (>66.77 cm). The additive interaction of rs 290487 and overweight/obesity variables yielded a significant increase in the risk for T2D. RERI (relative excess risk of interaction) was 2.949 (95%CI: 1.700-4.198), AP (attributable proportion due to interaction) was 0.391 (95%CI: 2.281-0.502), and SI (synergy index) was 1.822 (95%CI: 1.463-2.268). Additionally, there was a significant interaction between rs 290487 and abdominal obesity on the risk of T2D (RERI: 2.642, 95%CI: 1.384-3.900; AP: 0.350, 95%CI: 0.231-0.468; SI: 1.675, 95%CI: 1.348-2.083). CONCLUSIONS: These results show that a TCF7L2 gene-BMI interaction or gene-WC interaction may play an important role in the risk for T2D in the Chinese population.

9.
Acta Neurochir Suppl ; 127: 47-54, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31407062

RESUMO

BACKGROUND: Previously studies have shown that Nox2 and Nox4, as members of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase, Nox), participate in brain damage caused by ischemia-reperfusion (I/R). The aim of this study is to investigate the effects of specific chemical inhibitors of Nox2 and Nox4 on cerebral I/R-induced brain injury in rats. METHODS: At 0.5 h before MCAO surgery, the rats were pretreated with vehicle, Nox2 inhibitor (gp91ds-tat), and Nox4 inhibitor (GKT137831), respectively. After reperfusion for 24 h, the infarct sizes of brain tissues in rats in various groups are determined. The penumbra (ischemic) tissues are collected to measure ROS levels, neuronal apoptosis, and degeneration, as well as the integrity of the blood-brain barrier (BBB) in brain tissues of rats. RESULTS: gp91ds-tat and GKT137831 pretreatment significantly reduced the infarct sizes in brain tissues of rats, effectively suppressed I/R-induced increase in ROS levels, neuronal apoptosis and degeneration, and obviously alleviated BBB damage. CONCLUSION: Under cerebral I/R conditions, Nox2 inhibitor (gp91ds-tat) and Nox4 inhibitor (GKT137831) can effectively play a protective role in the brain tissues of rats.


Assuntos
Lesões Encefálicas , Isquemia Encefálica , NADPH Oxidase 2 , NADPH Oxidase 4 , Traumatismo por Reperfusão , Animais , Apoptose/efeitos dos fármacos , Lesões Encefálicas/tratamento farmacológico , Lesões Encefálicas/metabolismo , Isquemia Encefálica/tratamento farmacológico , Isquemia Encefálica/metabolismo , NADPH Oxidase 2/antagonistas & inibidores , NADPH Oxidase 2/metabolismo , NADPH Oxidase 4/antagonistas & inibidores , NADPH Oxidase 4/metabolismo , NADPH Oxidases , Ratos , Espécies Reativas de Oxigênio , Traumatismo por Reperfusão/metabolismo
10.
J Environ Sci (China) ; 87: 82-92, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31791520

RESUMO

Pot experiments were conducted to evaluate the effect of water management, namely continuous flooding (CF), intermittent flooding (IF) and non-flooding (NF), on Cd phytoavailaility in three paddy soils that differed in pH and in Cd concentrations. Diffusive gradients in thin films (DGT) technique was employed to monitor soil labile Cd and Fe concentrations simultaneously at three growth stages (tillering, heading and mature stage) of rice. The Cd phytoavailability were generally in the order of NF > IF > CF, and higher rice Cd (over permitted level, 0.2 mg/kg) were only found in neutral and acidic soils under NF conditions. DGT measured soil labile Cd rather than total Cd was the most reliable predictor for Cd accumulation in rice. CF enhanced the formation of root plaques, which related to oxidation of large quantities of available Fe on root surfaces due to the O2 secretion of rice root. The Cd concentration in root plaques shared the same trend with DGT-Cd. Generally, root plaques would inhibit Cd uptake by rice under CF conditions, while under IF and NF conditions, root plaques act as a temporarily store of Cd, and soil labile Cd is the key factor that controls the transfer of Cd from soil to rice. The results of principle component analysis revealed that water management had the greatest effect on soil Cd lability and rice Cd in acidic soil. Thus, it is important to consider the availability of Cd and soil pH when assessing current agricultural practices of contaminated soil in China.


Assuntos
Cádmio/análise , Oryza , Rizosfera , Poluentes do Solo/análise , Agricultura , China , Concentração de Íons de Hidrogênio
11.
PLoS One ; 14(12): e0224828, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31794559

RESUMO

There is currently no detailed evidence for the long-term effects of bariatric surgery on severely obese with type 2 diabetes, such as the risk of myocardial infarction and stroke. In order to provide evidence on the risks of macrovascular diseases and metabolic indicators of bariatric surgery follow-up for more than five years, we searched in the Cochrane library, Pubmed, and EMBASE databases from the earliest studies to January 31, 2019. Randomized clinical trials or cohort studies compared bariatric surgery and conventional medical therapy for long-term incidence of macrovascular events and metabolic outcomes in severely obese patients with T2DM. Fixed-effects and random-effects meta-analyses were performed to pool the relative risks (RRs), hazard ratios (HRs) and weighted mean difference (WMD). Publication bias and heterogeneity were examined. Four RCTs and six cohort studies were finally involved in this review. Patients in the bariatric surgery group as compared to the conventional treatment group had lower incidence of macrovascular complications (RR = 0.43, 95%CI = 0.27~0.70), cardiovascular events (CVEs) (HR = 0.52, 95%CI = 0.39~0.71), and myocardial infarction (MI) (RR = 0.40, 95%CI = 0.26~0.61). At the same time, the results demonstrate that bariatric surgery is associated with better weight and better glycemic control over the long-term than non-surgical therapies, and reveal that different surgical methods have different effects on various metabolic indicators. Bariatric surgery significantly decreases macrovascular complications over the long term and is associated with greater weight loss and better intermediate glucose outcomes among T2DM patients with severe obesity as compared to patients receiving only conservative medical measures.

12.
Comput Methods Programs Biomed ; 188: 105279, 2019 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-31865093

RESUMO

BACKGROUND AND OBJECTIVE: Characterizing the mechanical properties of the cancellous bone from the cervical vertebrae of child or child surrogate is important for the development of spine finite element models and the investigation of injury mechanism, however, there is currently no public data available as far as we know. METHODS: Compression tests were conducted on the specimens from the cervical vertebrae of 8-week-old piglets (child surrogates) in axial and radial directions at the strain rates of 0.01, 0.1, 1 and 10/s. The influences of directionality and strain rate on the mechanical properties of the vertebral cancellous bone were statistically investigated. The typical transversely isotropic model, which was added a strain rate item and a plasticity item, was implemented into LS-DYNA finite element code. Based on the material subroutine code, simulation was conducted on the vertebral tissue under compression in axial and radial directions at different strain rates. RESULTS: The mechanical properties of the cancellous bone of cervical vertebrae were obtained and most of the stress-strain curves showed major linear elastic stage and short plastic stage before fracture. Significant anisotropic behavior was observed for the vertebral tissue in axial and radial directions. The elastic modulus, ultimate stress,yield stress, and ultimate strain of the speimens in axial direction was obtained, with on average, 2.5 ±â€¯0.6 times, 2.1 ±â€¯0.15 times, and 2.1 ±â€¯0.1 times higher and 0.86 ± 0.076 times lower respecitvely, than those in radial direction. In addition, with the strain rate varying from 0.01/s to 10/s, the mechanical parameters, like elastic modulus, yield and ultimte stresses exhibited significant strain rate effect, however, no significant difference was found for the ultimate strain. CONCLUSIONS: The cervical vertebrae showed significant anisotropic and strain rate-dependent behaviors. The self-developed subroutine codes based on the strain rate-dependent transversely isotropic elastic and plastic constitutive model can simulate the behaviors well.

13.
Molecules ; 24(23)2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31757064

RESUMO

The sweet-mellow taste sensation is a unique and typical feature of premium congou black tea infusions. To explore the key taste-active compounds that influence the sweet-mellow taste, a sensory and molecular characterization was performed on thirty-three congou black tea infusions presenting different taste qualities, including the sweet-mellow, mellow-pure, or less-mellow taste. An integrated application of quantitative analysis of 48 taste-active compounds, taste contribution analysis, and further validation by taste supplementation experiments, combined with human sensory evaluation revealed that caffeine, γ-aminobutyric acid, rutin, succinic acid, citric acid, and gallic acid negatively affect the sweet-mellow taste, whereas glucose, sucrose, and ornithine positively contribute to the sweet-mellow taste of congou black tea infusions. Particularly, rutin, γ-aminobutyric acid, gallic acid, and caffeine, which impart the major inhibitory effect to the manifestation of the sweet-mellow taste, were identified as the key influencing components through stepwise screening and validation experiments. A modest level of these compounds was found to be favorable for the development and manifestation of the sweet-mellow taste. These compounds might potentially serve as the regulatory targets for oriented-manufacturing of high-quality sweet-mellow congou black tea.

14.
J Food Sci ; 84(12): 3411-3417, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31750940

RESUMO

Aroma assessment remains difficult and uncertain in the present sensory assessment system. It is highly desirable to develop a new assessment method to discriminate the quality of various teas in the tea market. In the present work, based on linear discriminant analysis and principal component analysis, the aroma of dry and wet samples of different Xi-hu Longjing and Pu-erh teas were tested and differentiated by electronic noses (e-nose). The results confirm that e-nose can discriminate different priced Xi-hu Longjing tea samples in the range of 80-800 RMB/500 g and varying storage years of Pu-erh tea samples. Furthermore, for the detection of both dry and wet samples of Longjing and Pu-erh teas, the results reveal that all samples have specific aroma characteristics that e-nose can recognize. More importantly, contribution analysis in sensors indicates that nitrogen oxides, methane and alcohols are the characteristic components that contribute to the fragrances of different priced Xi-hu Longjing teas, while nitrogen oxides, aromatic benzene and amines make the fragrances of Pu-erh teas with different storage years disparate. PRACTICAL APPLICATION: This work demonstrates that e-nose can rapidly distinguish tea products with different price levels and varying storage years. With the advantages of ease of use, high portability and flexibility, e-nose will be widely expanded and applied in refined processing and the development of flavored foods.

16.
Onco Targets Ther ; 12: 4993-5002, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31417288

RESUMO

Background: Dysregulation of a single miRNA can play an essential role in tumor development and progression. Recent studies have shown that miR-382-5p can function as an oncogene or as a tumor suppressor in different types of cancers. However, the role of miR-382-5p in glioma growth and expansion has not been characterized. Methods: Quantitative real time-PCR (qRT-PCR) was used to measure miR-382-5p levels in glioma tissues. The miR-382-5p mimics and inhibitors were employed to upregulate and downregulate miR-382-5p expression respectively in glioma cells. EdU assay was used to assess cell proliferation. Wound healing and Transwell assays were employed to evaluate cell migration and invasion. Western blot was used to measure the changes of epithelial-to-mesenchymal transition (EMT) markers and the potential miR-382-5p target genes. Results: We found that miR-382-5p levels were low in glioma tissues as determined by qRT-PCR. EdU assay showed that upregulation of miR-382-5p significantly decreased cell proliferation in both U87 and U251 cells. Wound healing rate was significantly decreased in response to miR-382-5p mimics and significantly increased in response to miR-382-5p inhibitors. Transwell migration assays further confirmed the inhibitory effects of miR-382-5p on the migration in both U251 and U87 cells. Transwell invasion assays showed that upregulation of miR-382-5p resulted in a remarkable decrease in the number of invading cells, whereas downregulation of miR-382-5p led to a significant increase in the numbers of invading U87 and U251 cells. In addition, overexpression of miR-382-5p decreased the protein levels of N-cadherin, Snail and Slug, and increased E-cadherin levels, in glioma cells. Furthermore, miR-382-5p levels negatively correlated with Y box-binding protein 1 (YBX1) in lower grade glioma tissues, and negatively regulated the expression of YBX1 in glioma cells. Conclusion: In summary, miR-382-5p inhibited proliferation, migration, invasion, and the EMT in glioma cells, possibly through targeting the oncogene YBX1.

17.
Bioresour Technol ; 292: 121948, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31408776

RESUMO

To improve the adsorption efficiency, a H3PO4-modified biochar (CFCP) was prepared using chicken feather and applied to Cd2+ and Pb2+ adsorption. The pseudo-second-order model could explain the Cd2+ and Pb2+ adsorption behavior. CFCP had faster adsorption rate than non-modified biochar (CFC2). The Langmuir and Freundlich isotherm could better describe the Cd2+ and Pb2+ adsorption, respectively. The value of qm for Cd2+ adsorption and KF for Pb2+ adsorption by CFCP was 7.84 mg·g-1 and 24.41 mg1-(1/n)·L1/n·g-1, which was 1.38 and 5.41 times of the corresponding results of CFC2. Relative to Cd2+, Pb2+ was selectively adsorbed by biochars in the binary metal system. Phosphate precipitation explained in part the selective adsorption of Pb2+. Proline, glucose, and pH (4-6) had little influence on Cd2+ and Pb2+ adsorption. Electrostatic interaction, precipitation, and O-H bonds were the primary adsorption mechanisms. The increased N-containing heterocycles of CFCP accounted for the increased Cd2+ and Pb2+ adsorption.


Assuntos
Cádmio , Galinhas , Adsorção , Animais , Carvão Vegetal , Plumas , Íons , Chumbo , Ácidos Fosfóricos
18.
J Environ Manage ; 249: 109425, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31446121

RESUMO

In the present study, the biodegradation behaviors of petroleum hydrocarbons under various reducing conditions were investigated. n-Alkanes and polycyclic aromatic hydrocarbons (PAHs) were degraded with NO3-, Fe3+, SO42-, or HCO3- as terminal electron acceptors (TEAs), which link to four typical reducing conditions (i.e., nitrate-reducing, ferric-reducing, sulfate-reducing and methanogenic conditions, respectively) in sediment. The fastest degradation rates were achieved under sulfate-reducing conditions with half-lives of 49.51 days for n-alkanes and 58.74 days for PAHs. For short-chain n-alkanes and low-molecular weight (LMW) PAHs, relatively higher removal efficiencies were achieved under nitrate- and ferric-reducing conditions. The degradation of long-chain n-alkanes and high-molecular weight (HMW) PAHs coupled to methanogenesis was the most favored as compared with other reducing conditions. Carboxylation was found to be the principle mechanism for regulating n-alkane degradation coupled to denitrification, while the activation of n-alkanes by the addition of fumarate was the principle mechanism for the n-alkane degradation under sulfate-reducing conditions. The anaerobic metabolism of n-alkanes may not proceed via fumarate addition or carboxylation under ferric-reducing and methanogenic conditions. Illumina HiSeq sequencing revealed dissimilar structures of the microbial communities under various reducing conditions. It is hypothesized that the utilization of different TEAs for n-alkane and PAH degradation resulted in distinct microbial community structures, which were highly correlated with the varied degradation behaviors of petroleum hydrocarbons in sediment. The current results may provide reference value on better understanding the biodegradation behaviors of n-alkanes and PAHs in association with the induced microbial communities in sedimentary environments under the four typical reducing conditions.


Assuntos
Microbiota , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Biodegradação Ambiental , Hidrocarbonetos , Sulfatos
19.
Environ Pollut ; 254(Pt A): 112938, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31404731

RESUMO

In the present study, the competitive adsorption of Cu2+, Pb2+, and Cd2+ by a novel natural adsorbent (i.e., argillaceous limestone) modified with chitosan (C-AL) was investigated. The results demonstrated that both intraparticle diffusion and chemisorption marked significant contributions to the Cu2+ adsorption process by both raw argillaceous limestone (R-AL) and C-AL in mono-metal adsorption systems. Antagonism was found to be the predominant competitive effect for Cu2+, Pb2+ and Cd2+ adsorptions by C-AL in the multi-metal adsorption system. The three-dimensional simulation and FTIR analysis revealed that the presence of Cu2+ suppressed Pb2+ and Cd2+ adsorptions, while the effect of Cd2+ on Cu2+ and Pb2+ adsorptions was insignificant. The spectroscopic analyses evidenced that amide groups in C-AL played a crucial role in metal adsorption. The preferential adsorptions of Pb2+ > Cu2+ > Cd2+ were likely due to the different affinities of the metals to the lone pair of electrons on the N atom from the amide groups and/or the O atoms from the -OH and -COO- groups on C-AL. The interactions between C-AL and metal ions and between various metal species influenced their competitive adsorption behaviors. C-AL exhibited a superior metal adsorption capacity in comparison with that the capacities of other natural adsorbents reported during the last decade, suggesting its potential practical applications.


Assuntos
Cádmio/química , Carbonato de Cálcio/química , Quitosana/química , Cobre/química , Recuperação e Remediação Ambiental/métodos , Chumbo/química , Adsorção , Íons , Metais Pesados/química , Análise Espectral
20.
Sci Total Environ ; 690: 438-446, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31299576

RESUMO

The application of iron oxide nanoparticles (IONs) is often limited by agglomeration and low loading. Here, we presented a facile phase change material (PCM) -based sol-gel strategy for the fabrication of α-Fe2O3 nanoparticles. Rosin was used as the PCM in the sol-gel process and the carbon-based substrate of α-Fe2O3 nanoparticles in the thermal process. The α-Fe2O3 nanoparticle embedded rosin-derived biochar(α-Fe2O3@HrBc)were highly dispersed. The dispersity of α-Fe2O3 nanoparticle could be regulated by the weight ratios of rosin to FeCl3·6H2O during the preparation, as evidenced by the scanning electron microscope (SEM) spectrum and the sorption capacity results. Among a series of α-Fe2O3@HrBc nanocomposites, the one with the weight ratios of 1/1.5 rosin/FeCl3·6H2O had the highest capacity for hexavalent chromium (Cr(VI)) sorption. This phenomenon can be ascribed to a remarkably enhanced interfacial reactivity due to an increase in the dispersity of α-Fe2O3 nanoparticle. In addition, SEM showed that the majority of α-Fe2O3 nanoparticles was dispersed on and inside the biochar substrate. Batch adsorption experiments revealed that the α-Fe2O3@HrBc adsorbed 90% Cr(VI) within one minute, and the maximum capacity was up to 166 mg·g-1 based on the Langmuir model. The FTIR and XPS spectra revealed that the adsorbed Cr(VI) species were partially reduced to less toxic Cr(III). Considering that α-Fe2O3 nanoparticles provided important sorption sites, the newly formed Cr(III) and the remaining Cr(VI) ions could be adsorbed on α-Fe2O3@HrBc via the formation of FeCr coprecipitation.

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