Preparation and Performance of Bitumen Modified by Melt-Blown Fabric of Waste Mask Based on Grey Relational and Radar Chart Analysis.

To effectively utilize waste mask materials in road engineering and minimize resource waste, the melt-blown fabric (MBF) of waste masks was utilized to modify the virgin bitumen. The preparation process of MBF-modified bitumen was investigated, and the physical and rheological properties of bitumen were measured. Subsequently, the blending mechanism during preparation and the dispersion morphology of the modifier were explored. Finally, the pavement performance of the mixture was investigated, and a radar chart analysis was performed to quantitatively assess the effects of MBF modification. Results suggested that the recommended preparation process of shear time, shear rate, and shear temperature was 170 °C, 4000 r/min, and 15 min, respectively. MBF enhanced the high-temperature stability of the binder and weakened the temperature susceptibility. The modification was primarily a physical process. No network structure and agglomeration formed in the bitumen after modification. The addition of MBF significantly improved the resistance of the asphalt mixture to a high-temperature deformation and water damage but harmed its low-temperature crack resistance. The comprehensive assessment results of 0% (f1), 1% (f2), 3% (f3), and 5% (f4) MBF to improve the properties of the mixture were in the following order: f3>f4>f2>f1, where the impact of 3% MBF was the most significant, followed by 5% and 1% MBF.

Analysis on the synergistic variation law of pile refreezing process and bearing capacity based on high-strain dynamic test method.

The high-strain dynamic test method possesses the attributes of speed, efficiency, and environmentally-friendly, low-carbon characteristics. To study the reliability of the high-strain dynamic test method in detecting the bearing capacity of pile foundation in permafrost regions, 4 test piles, each with a length of 15 m and a diameter of 1.0 m, were poured based on the actual bridge construction project in the permafrost region of Daxing'an Mountains in China. Based on the temperature data between the piles and soil, the refreezing state of the pile foundation was comprehensively judged. Subsequently, the static method was employed to assess the friction resistance values and single pile bearing capacity of each soil layer on the pile side under different freezing states before and after the pile foundation refreezing. Building upon these findings, the restrictive parameters for soil elastic limit [Formula: see text], soil resistance [Formula: see text] and other parameters in the pile-soil model of high-strain dynamic test method are clarified. The test and analysis results indicate that under the condition that the ground temperature of frozen soil is about - 1.9 °C, the pile-soil refreezing takes about 120 days, and the pile-soil refreezing is a slow process; In CAPWAPC calculation program, after the values of soil parameters were constrained by the results of static-load test, the calculated curve is in satisfactory agreement with the measured curve, and the parameters of the pile-soil model are reliable, which can be used for the rapid detection of the ultimate bearing capacity of piles in permafrost regions; In the process of pile-soil refreezing, the change of temperature field affects the freezing strength between pile and soil, the process of pile-soil refreezing is positively correlated with the increase of pile foundation bearing capacity.

Modification-Free Fluorescent Biosensor for CEA Based on Polydopamine-Coated Upconversion Nanoparticles.

Upconversion nanoparticles (UCNPs) have achieved considerable success in protein sensing in vitro. And aptamer is one of the most frequently used biomolecules to modify the nanoparticles for protein assay. However, the complicated process of modifying UCNPs with DNA and the susceptibility of the phosphate groups of DNA backbone to adsorb on the surface of UCNPs have limited their practical applications. To overcome these limitations, a modification-free fluorescent biosensor based on polydopamine-coated upconversion nanoparticles (UCNPs@PDA) is proposed. It consists of UCNPs@PDA and CEA aptamer-functionalized AuNPs (AuNPs-CEA aptamer). The CEA aptamer on AuNPs can be adsorbed onto the surface of UCNPs@PDA due to the interactions of π-π stacking and hydrogen bonding, triggering the process of fluorescence resonance energy transfer (FRET) from UCNPs@PDA to AuNPs-CEA aptamer. In the presence of CEA, the AuNPs-CEA aptamer departs from UCNPs@PDA due to the stronger affinity of CEA with its aptamer. Therefore, the recovery of upconversion fluorescence can sensitively quantify the concentration of CEA. This biosensor provides a linear range from 0.1 to 100 ng/mL for CEA with a LOD of 0.031 ng/mL in an aqueous solution. In spiked human serum samples, the same linear range is acquired with a slightly higher LOD of 0.055 ng/mL, demonstrating the great potential of the biosensor in practical application.

Polychlorinated Dibenzo-p-Dioxins, Polychlorinated Dibenzofurans, and Dioxin-Like Polychlorinated Biphenyls in Umbilical Cord Serum from Pregnant Women Living Near a Chemical Plant in Tianjin, China.

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (dl-PCBs) are bioaccumulative compounds that may affect fetal growth and infant development. The aim of this study was to determine whether the pregnant women living near a chemical plant in Tianjin had a risk of exposure to dioxins. Concentrations of PCDD/Fs and dl-PCBs in 24 umbilical cord serum samples collected from pregnant women were measured using a high-resolution gas chromatograph with a high-resolution mass spectrometer (HRGC-HRMS) and an isotopic dilution method. The levels of ∑(PCDD/Fs + dl-PCBs) were in the range 476-8307 pg·g-1 lipid, with a mean of 3037 pg·g-1. The mean World Health Organization toxicity equivalent (WHO-TEQ) for PCDD/Fs and dl-PCBs was 14.0 and 2.14 pg·g-1 lipid, respectively. The PCDD/Fs and dl-PCBs contributed 86.7% and 13.3%, respectively, to the total TEQ. The octa-CDFs and penta-CBs were predominant for the PCDD/Fs and dl-PCBs, accounting for 57.6% and 74.3%, respectively. Several PCDD/F and dl-PCB congeners were highly correlated, such as PCB 105 and PCB 118 (r = 0.982, p < 0.001). Although the results hint at decreasing trends for PCDD/F and dl-PCBs by comparison with a similar study in Tianjin, a total TEQ of 41.7% of study participants had a body burden that exceeded the biomonitoring equivalents for dioxins. It was shown that pregnant women and infants had a health risk of exposure to dioxins.

Mesoporous Carbon and Ceria Nanoparticles Composite Modified Electrode for the Simultaneous Determination of Hydroquinone and Catechol.

In this work, a novel material that was based on mesoporous carbon and ceria nanoparticles composite (MC⁻CeNPs) was synthesized, and a modified electrode was fabricated. When compared with a bare glass electrode, the modified electrode exhibited enhanced electrocatalytic activity towards the simultaneous determination of hydroquinone (HQ) and catechol (CC), which is attributed to the large specific area and fast electron transfer ability of MC⁻CeNPs. Additionally, it exhibited linear response ranges in the concentrations of 0.5⁻500 µM and 0.4⁻320 µM for HQ and CC, with detection limits (S/N = 3) of 0.24 µM and 0.13 µM, respectively. This method also displayed good stability and reproducibility. Furthermore, the modified electrode was applied to the simultaneous determination of HQ and CC in tap and lake water samples, and it exhibited satisfactory recovery levels of 98.5⁻103.2% and 98⁻103.4% for HQ and CC, respectively. All of these results indicate that a MC⁻CeNPs modified electrode could be a candidate for the determination of HQ and CC.

The effects of Bi2O3 on the selective catalytic reduction of NO by propylene over Co3O4 nanoplates.

Bi2O3/Co3O4 catalysts prepared by the impregnation method were investigated for the selective catalytic reduction of NO by C3H6 (C3H6-SCR) in the presence of O2. Their physicochemical properties were analyzed with SEM, XRD, H2-TPR, XPS, PL and IR measurements. It was found that the deposition of Bi2O3 on Co3O4 nanoplates enhanced the catalytic activity, especially at low reaction temperature. The SO2 tolerance of Co3O4 in C3H6-SCR activity was also improved with the addition of Bi2O3. Among all catalysts tested, 10.0 wt% Bi2O3/Co3O4 achieved a 90% NO conversion at 200 °C with the total flow rate of 200 mL min-1 (GHSV 30 000 h-1). No loss in its C3H6-SCR activity was observed at different temperatures after the addition of 100 ppm of SO2 to the reaction mixture. These enhanced catalytic behaviors may be associated with the improved oxidizing characteristics of 10.0 wt% Bi2O3/Co3O2. XRD results showed that Bi2O3 entered the lattice of Co3O4, resulting in the formation of lattice distortion and structural defects. H2-TPR results showed that the reduction of Co3O4 was promoted and the diffusion of oxygen was accelerated with the addition of Bi2O3. XPS measurements implied that more Co3+ formed on the 10.0% Bi2O3/Co3O2 catalysts. The improved oxidizing characteristics of the catalyst with the addition of Bi2O3 due to the synergistic effect of the nanostructure hybrid, thus enhanced the C3H6-SCR reaction and hindered the oxidization of SO2. Therefore, the 10.0% Bi2O3/Co3O4 catalyst exhibited the highest NO conversion and strongest SO2 tolerance ability.

Enhancement of waste activated sludge dewaterability using calcium peroxide pre-oxidation and chemical re-flocculation.

The effects of combined calcium peroxide (CaO2) oxidation with chemical re-flocculation on dewatering performance and physicochemical properties of waste activated sludge was investigated in this study. The evolutions of extracellular polymeric substances (EPS) distribution, composition and morphological properties were analyzed to unravel the sludge conditioning mechanism. It was found that sludge filtration performance was enhanced by calcium peroxide oxidation with the optimal dosage of 20 mg/gTSS. However, this enhancement was not observed at lower dosages due to the absence of oxidation and the performance deteriorated at higher dosages because of the release of excess EPS, mainly as protein-like substances. The variation in soluble EPS (SEPS) component can be fitted well with pseudo-zero-order kinetic model under CaO2 treatment. At the same time, extractable EPS content (SEPS and loosely bound EPS (LB-EPS)) were dramatically increased, indicating sludge flocs were effectively broken and their structure became looser after CaO2 addition. The sludge floc structure was reconstructed and sludge dewaterability was significantly enhanced using chemical re-flocculation (polyaluminium chloride (PACl), ferric iron (FeCl3) and polyacrylamide (PAM)). The inorganic coagulants performed better in improving sludge filtration dewatering performance and reducing cake moisture content than organic polymer, since they could act as skeleton builders and decrease the sludge compressibility.

[Influencing Mechanism of Titanium Salt Coagulant Chemical Conditioning on the Physical and Chemical Properties of Activated Sludge Flocs].

The effect of the different forms of titanium salt coagulant conditioning on sludge dewatering performance was studied. The result showed that the sludge dewaterability was the best and the specific resistance to filtration (SRF), the compressibility and the content of organic content in EPS were the lowest when B=0.5 compared with others. The optimal dosage of polymeric titanium chloride (PTC) was 0.005 g·g-1, which was far less than those of the traditional iron salts and aluminum coagulants. When the dosage of PTC with different B values was 0.005 g·g-1, the order of dewaterability was:PTC 0.5> PTC1.5> TiCl4> PTC2.5. In addition, the variations of characteristics such as particle size (d0.5) and fractal dimension(DF) of sludge during conditioning were analyzed. The effect of titanium salt coagulant conditioning on the distribution and composition of the sludge extracellular polymeric substance(EPS) was characterized by Three-dimensional Excitation Emission Matrix Fluorescence (3DEEM) and High Performance Size Exclusion Chromatography(HPSEC).The decrease of fluorescent intensity and molecular weight of peak distribution and intensity of organics in EPS was highly correlated to the improvement of the dewatering performance and change of sludge properties.

Studies on the photodegradation of Rhodamine dyes on nanometer-sized zinc oxide.

The nanometer-sized ZnO was prepared through the sol-gel method. Its average particle diameter, determined by TEM, was 20-30 nm. The specific surface area was determined to be 22 m2 g(-1) by BET. The photodegradation mechanism of Rhodamine dyes on nanometer-sized ZnO was studied by dynamic molecular spectra, and the results showed that the photodegradation of Rhodamine dyes obeyed the rules of a pseudo first-order kinetic reaction. The rate constant k of the degradation of Rhodamine B (RB) and butyl-Rhodamine (BR) were 0.0128 and 0.0154 min(-1), respectively, and the half period t(1/2) were 60 and 52 min, respectively. The photodegradation reaction conditions were optimized. After intermixing with silver, the photodegradation efficiency was greatly improved. A life-span test showed that nanometer-sized ZnO had a long life-span.