Reptiles are an important part of vertebrates and are the primitive terrestrial vertebrates. However, lots of reptile species are endangered or susceptible to extinction. It is no doubt that ...contaminants are one of the important reasons for the decline of the lizard population. In this study, the selective metabolism of triadimenol (TN) in the male
Eremias argus
lizards and the toxic effects of TN on lizards were studied. TN chiral isomers were separated and detected by HPLC-MS/MS system with Lux Cellulose-1 column. Tissue distribution experiments showed the existence of stereoselectivity biotransformation of TN enantiomers among organs in lizards, and RR-TN preferentially emerged over the other enantiomers. The antioxidant enzymes (SOD, CAT, GST) activities and MDA content assays demonstrated that TN induced oxidative stress in most organs, especially in the liver, and the histopathology analysis showed the severe liver and testis damage caused by 14-day continuous TN gavage. The reproductive effects of TN-induced reflected in the increased sex hormone testosterone. This research confirms that TN could induce hepatic and reproductive toxicity of
E. argus
lizard.
•A method for detecting cyanamide in 21 plant-derived foods was developed.•The method is simple, sensitive, and widely applicable.•This method has good accuracy and precision.
Cyanamide is widely ...used in agriculture, and has a modest toxicity in humans. In the present study, a simple, sensitive, and widely applicable method for detecting cyanamide in 21 plant-derived foods was developed. In the proposed method, after the samples were homogenized and extracted, the method employs clean-up with multi-walled carbon nanotubes (MWCNTs) and derivatization with dansyl chloride. The derivatized sample extracts were quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS). The mean recoveries were in the range of 67.4%–107.1%, and the RSDs were between 1.0% and 17.8%. The quantification limit in shiitake, green tea and chinese pepper was 0.05mg/kg, and in others 18 plant-derived foods was 0.01mg/kg. Among the data of 5 different laboratories, the repeatability limits (r) ranged from 0.0010 to 0.0941, and the reproducibility limits (R) ranged from 0.0031 to 0.2667. Moreover, the repeatability among different testing personnels in the same laboratory also has been examined.
Microcosms containing DDT spiked-sediment, Tubifex tubifex and carp (Cyprinus carpio) were constructed to simulate a freshwater system. The accumulation, elimination and toxic effects of DDT ...(p,p'-DDT, o,p'-DDT), and its metabolites DDD (p,p'-DDD, o,p'-DDD) and DDE (p,p'-DDE, o,p'-DDE) were studied in T. tubifex and carp. Tissue/organ distributions of DDTs were also investigated in carp. The bioaccumulation and elimination of DDT differed in T. tubifex, carp and its tissues/organs. Unimodal or bimodal distributions were observed, and the concentrations of DDT metabolites (DDD and p,p'-DDE) increased over time. The carp organ with the highest concentrations of DDTs (DDT, DDD and DDE) was the gill. The largest mass distribution of DDTs was also in gill, followed by muscle and gastrointestinal tract. Maximum levels of DDTs in whole carp and carp muscle were 161 and 87 ng/g, respectively; therefore, the levels of DDTs observed in carp in this study were insufficient to constitute a health concern if present in fish for human consumption. Significant changes were observed in some biomarkers, including superoxide dismutase, catalase, glutathione-S-transferase, glutathione, and carboxylesterase, in T. tubifex and carp tissues during DDT exposure. Tissue-specific accumulation of DDTs in carp can be a key indicator of exposure to environmentally relevant concentrations.
•As a green and carbon-friendly grouting material, RGGM was prepared with industrial by-products at ambient temperature.•Models of the initial fluidity and mechanical strength of RGGM were developed ...using Response Surface Methodology (RSM).•RSM coupled with MOPSO algorithm was implemented for predicting and optimizing the properties of RGGM.•The predicted results obtained just brought a difference around 5% from the experiments results.
As a green and carbon-friendly material, road geopolymer grouting material (RGGM) has a great application potential as a replacement of cement grouting materials in subgrade reinforcement. However, the diversity of its components, including mineral precursors and activators, may mislead engineers in evaluating its performance, especially its fluidity and strength, which limits the popularization and application of RGGM. For this, a Response Surface Methodology (RSM) coupled with multi-objective particle swarm optimization (MOPSO) algorithm was developed for predicting and optimizing the variables that affect the initial fluidity and mechanical strength of RGGM. Initially, a Central-Composite Design (CCD) of RSM has been adopted to establish the statistical models of three responses (28d compressive strength, 28d flexural strength and initial Marsh time) of RGGM. Then, the significant effect of different variables on the three responses was investigated by ANOVA and 3D surface diagrams. Finally, MOPSO algorithm was applied to find global solutions using the three statistical models and optimize the multi-performances of RGGM. It is found that all statistical models are significant because the R-squared are more than 0.9, which can also be verified by the Normal probability plot and Predicted vs actual plot. The effect of water consumption on the three responses is the most significant among the single factors, and for the interaction factors, the interaction between water and NaOH is the most significant. Through the optimization of RSM coupled with MOPSO algorithm, the optimal solutions are predicted and verified only about 5% difference from the experimental results. This optimization method (RSM + MOPSO) is helpful for engineers and researchers to have a comprehensive understanding of the performances of RGGM, which will promote its application to cleaner road reinforcement in road engineering.
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•Provide a new insight for exploring the UV aging mechanism of asphalt binders.•Explore the effects of some potential influencing factors and their interactions on the UV aging ...characteristics of asphalt binders with RSM method.•Characterize the micro properties of asphalt binders irradiated by UV light with different wavelengths through some microscopic experiments.
To explore the UV aging characteristics of asphalt, effects of potential influencing factors as well as their interactions on asphalt’s properties were investigated with the aid of Response Surface Methodology (RSM). Four influencing factors, including ultraviolet irritation wavelength, irritation intensity, asphalt film thickness, and aging temperature, were selected as the response variables of RSM. And complex shear modulus aging index G*AI, DSR function aging index DAI and fatigue factor aging index FAI were selected as the responses’ values. Then, the Central Composite Design (CCD) model of RSM was adopted to establish the statistical models to analyze the effects of different variables on asphalt’s UV aging behaviors. On this basis, aging degree of asphalt under ultraviolet irradiation with different wavelengths was analyzed emphatically with Fourier Transform Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM) tests. Meanwhile, method for speeding up the efficiency of asphalt UV aging test by reducing the asphalt film was also proposed. Test results show that UV aging rate of asphalt increases gradually with the decreasing of asphalt film and the increasing of radiation intensity and aging temperature; among them, the effect of asphalt film thickness is the greatest, while that of aging temperature is the smallest. In addition, radiations with different wavelength have different effects on UV aging behaviors of asphalt, and asphalt irradiated by UV-340 to UV-360 has the highest aging degree, which can be further proved by FTIR and AFM test results. Interactions between different factors will also affect the UV aging characteristics of asphalt, and the results are related to the types of asphalt. However, interaction between UV radiation wavelength and asphalt film thickness all have the significant effects on the UV aging behaviors of base asphalt and SBS modified asphalt. Decreasing the asphalt film thickness can effectively increase the UV aging rate of asphalt. Thus, the aging time can be appropriately reduced on the basis of thinner asphalt film, so as to improve the test efficiency. And finally, it can be found that two processes may exist during the UV aging process of asphalt, namely molecular excitation process and chemical bond breaking process. Under the two actions, unstable chemical bonds in asphalt will reach the excited state or break, and combine easily with the oxygen atom and then generate some polar oxygen-containing functional groups, thus causing the decline of asphalt’s properties.
•A green road grouting material AASFGM was prepared at ambient temperature.•A multi-index optimization design based grey correlation and objective weighting is applied systematically.•The physical ...properties of AASFGM were tested and compared with those of cement grouting materials.•The microstructure and strength development mechanism of AASFGM was further characterized.
As a green and carbon-friendly material, alkali-activated grouting material (AAGM) has great application potential in reinforcement engineering. In this study, the alkali-activated slag/fly ash grouting material (AASFGM) was prepared with industrial-waste ground granulated blast-furnace slag (GGBS) and fly ash (FA) as raw materials. In order to meet the multi-performance requirements, a multi-index optimization design based on grey correlation and objective weight was adopted to prepare AASFGM pastes. And its physical performances including fresh and harden properties were tested and compared with those of cement grouting materials (CGM), more than that, the microstructure and strength development mechanism of AASFGM was further characterized by means of X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive Spectrum (EDS) and Fourier transform infrared spectroscopy (FT-IR). It is found that the AASFGM paste possesses clean production, high mechanical strength, high fluidity, low bleeding rate and low porosity, providing appealing properties as grouting materials for reinforcement. The new multi-index optimization method, based on grey correlation and objective weights determined, is much more scientific and objective to obtain a balanced performance for AASFGM preparation. The optimized AASFGM paste has a uniform and compact microstructure, and it also has remarkable advantages in mechanical strength, bleeding rate and porosity compared with CGM. As a carbon-friendly grouting material, it may become a greener substitute of CGM for the cleaner reinforcement engineering.
The porous asphalt pavements is often used in important occasion for its special properties and performance which can be to a great extent attributed to the binder—high viscosity and elasticity ...asphalt (HVEA). To prepare high demanding binder for porous asphalt pavements, the polyurethane prepolymer (PUP) and styrene–butadiene–styrene (SBS) were used to modify the matrix asphalt compositely. First, based on a series of physical tests, the effects of binder composition on performance of SBS/PUP HVEA binder (SBS/PUP‐HVEA) were investigated. Then the Fourier transform infrared (FTIR) test was conducted to investigate the reaction mechanism of SBS/PUP‐HVEA binder. Last, the fluorescence microscopy, stability tests, multiple stress creep recovery test, and differential scanning calorimetry test were carried out to evaluate and compare the phase structure, storage, high‐temperature performance, thermostability characteristics of several HVEA binders. It is found that the composite modification of SBS and PUP can produce high quality binder which possesses high viscosity and high elasticity. And the composition of SBS/PUP‐HVEA were recommended as follows: Shell‐70# can be chosen as matrix asphalt, the contents of SBS modifier (SBS1301:SBS4303 = 1:2), H2122A PUP, chain extender M‐OEA, and crosslinker sulfur were suggested 4%, 5%, 0.5%, and 1‰, respectively. The new functional groups observed in FTIR confirmed the existence of physical and chemical reactions in the modification process, which were beneficial to improve the high temperature performance and storage stability of the binder. SBS/PUP‐HVEA had good phase structure, storage stability, high temperature performance, and thermostability compared to other HVEA binders. This study demonstrated that the SBS/PUP compositely modified asphalt possessed high viscosity and high elasticity, which can be used in the porous asphalt mixture and other highly demanding working environment as well.
As a promising sustainable building material, geopolymer/steel-slag composite materials have been poorly known in the field of the interfacial characteristics of geopolymer/steel-slag interface, ...especially at the molecular level. Herein, in this work, molecular dynamics simulation was employed to reveal the interfacial characteristics and mechanical behaviors of geopolymer binder with steel slag aggregate. The molecular models of two geopolymer binders (C-A-S-H and N-A-S-H) and three main minerals of steel slag aggregate (Ca2SiO4, Ca2Fe2O5 and CaCO3) were constructed and carried out. Then the wetting characteristics of different mineral surfaces, interfacial characteristics, interaction mechanisms and mechanical behaviors of various geopolymer/steel-slag interfacial systems were elucidated and compared. It is found that the Ca2SiO4, Ca2Fe2O5 and CaCO3 of steel slag aggregate show strong hydrophilicity, attracting water molecules to accumulated on its mineral surface and promoting the diffusion of Ca2+ and Na + at the interface. The interaction energy of geopolymer/steel-slag systems is mainly composed of electrostatic interaction energy. Thanks to the accumulation of water molecules on the mineral surface, the stronger hydrogen bond interaction occurs at the interface of the geopolymer/steel-slag system. The free metal cations from mineral surfaces and geopolymer binder respectively are coordinated with the accumulated water molecules to emerge hydrated ions, forming composite ionic clusters to stabilize the interfacial interaction. Mechanically, the interaction systems with C-A-S-H binder possess stronger interfacial tensile strength and shear strength. Steel slag with higher Ca2SiO4 content can effectively form strong interfacial bonding, lowering the risk of interfacial tensile failure, whereas steel slag containing more Ca2Fe2O5 can reduce occurrence possibility of shearing damage. CaCO3 formed by carbonization of steel slag, is conductive to strengthening the interfacial interaction with geopolymer binder.
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•MD simulation can reveal the interfacial behaviors of geopolymer/steel-slag.•The interfacial interaction of geopolymer/steel-slag is mainly composed of electrostatic interaction.•The water molecules at the interface produce hydrogen bond interaction.•The water molecules, Ca2+ and Na + migrate to the interface to form hydrated ions.
•A green road grouting material was prepared at ambient temperature.•Provide a pathway to reduce drying shrinkage of geopolymeric grouts.•The modification mechanism of silicon-acrylic (SiA) latex ...contains physical and chemical aspects.
As a green and carbon-friendly material, road geopolymeric grouts have a great application potential as a replacement of cement-based grouts in road reinforcement, but it still possesses some shortcomings, including high drying shrinkage and poor toughness. In this study, four water-soluble polymer latexes were used to prepare the latex modified geopolymeric grouts (LMGG). Four material composition factors, including mixing ratio of mineral precursors, kinds and contents of alkali activators, water-solid ratios and kinds and contents of polymer latexes, were investigated to discuss the effect of each factor on LMGG paste. Then, the physical properties of LMGG were explored and compared with cement-based grouts. Finally, the Mercury Intrusion Porosimetry (MIP), X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive Spectrum (EDS) and Fourier transform infrared spectroscopy (FT-IR) were used to explore the pore structure, product phase, micromorphology and functional groups to reveal its modification mechanism. In this study, the effects of compositions (mineral precursors, alkali activators, water and polymer latexes) on LMGG pastes were studied and optimized. Using water glass and KOH as activators can obtain excellent strength and initial fluidity. And the addition of 5 wt% silicon-acrylic (SiA) polymer latex had a positive effect on the strength, shrinkage and pore size distribution, improving 7 d compressive strength by 8.1%, 7 d flexural strength by 19.9%, proportion of gel and medium pores by 28.0%, and reducing the total shrinkage by 63.5%. With the addition of SiA latex, the characterization of hydration and geopolymerization product phases of geopolymeric grouts does not change. The modification mechanism of SiA latex in LMGG system involves physical and chemical modification processes. In physical aspect, the polymeric film can be interweaved and wrapped with the geopolymer products, filling cracks and pores. And in chemical aspect, the active groups of SiA latex reacted with the geopolymer products linking the polymer chains with geopolymer products together.
•Analyze the UV aging characteristics of asphalt binders from multiple scales.•Explore the effects of UV aging on rheological properties of asphalt binders based on some rheological models.•Propose ...some suitable evaluation indexes to quantitatively characterize the UV aging degree of asphalt binders.•Discuss the relationships among the macro properties and micro properties of asphalt binders before and after UV aging.
Aiming to propose some suitable evaluation indexes to quantitatively characterize the UV aging resistance of asphalt binders, firstly, effects of UV aging on asphalt’s properties were comprehensively explored from the multiple scales, including their physical rheological properties, chemical compositions and microscope morphology. The above properties of asphalt binders before and after UV aging were respectively measured with the conventional physical properties tests, dynamic shear rheometer (DSR) test, thin-layer chromatography test (TLC) test, gel permeation chromatography (GPC) test and atomic force microscopy (AFM) test. Subsequently, based on some principles for establishing evaluation indexes, such as discrimination, regularity and consistency, the optimal evaluation indexes were proposed to quantitatively characterize the UV aging resistance of asphalt binders. Finally, relationships between the physical properties, chemical compositions and micro morphology of asphalt binders were discussed with the Pearson correlation coefficient method. Test results show that UV aging has a significant effect on physical rheological properties of asphalt, and ranking of aging resistances among asphalt binders evaluated by different macro indices are nearly consistent. Among these macro indexes, the G-R parameter aging index are proved to be the evaluation index with the highest discrimination degree, followed by complex shear modulus G* aging index (60 °C, 10 rad/s, 1 %) and zero shearing viscosity ZSV aging index (60 °C). Chemical composition test results demonstrate that with the growth of UV aging degree, resins components in asphalt increase gradually, while aromatics components decrease, which results in the proportion of larger molecular size (LMS) in asphalt gradually increases. And AFM test results show that UV aging will cause the number of the “bee structure” and roughness values of asphalt gradually decrease, thus promoting the transformation of the asphalt micro structure to smooth. Pearson correlation analysis indicates the compared with the roughness Ra, the Gel index Ic and LMS possesses higher correlation with G-R and G*, whose R values both exceed 0.8. Thus, it may be appropriate to adopt some chemical composition evaluation indexes (such as Ic, LMS) to characterize the UV aging degree of asphalt binders from the microscope perspective.
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