Comparison of pollution characteristics and magnetic response of heavy metals in dustfall before and after COVID-19 outbreak in Shanghai

In this study, dustfall samples were systematically collected in various regions of Shanghai before and after the occurrence of COVID-19 in December 2019 and December 2020. The magnetic response, content and pollution status of relevant heavy metal elements in the samples were analyzed using environmental magnetism, geochemistry, scanning electron microscopy (SEM) and the enrichment factor (EF) method. The results show that the magnetic particles in the dustfall samples are mainly pseudo-single-domain (PSD) and multi-domain (MD) ferrimagnetic minerals, and Fe, Zn, Cr, and Cu are mainly concentrated in the districts with intensive human activities. Due to restrictions on human activities following the COVID-19 epidemic, both the values of magnetic parameters and the heavy metal pollution level in 2019 are more significant than those in 2020, which is consistent with the Air Quality Index (AQI) results. In addition, magnetic susceptibility (χlf), non-hysteresis remanence (χARM) and saturation isothermal remanence (SIRM) have different degrees of correlation with heavy metal elements, and the correlations with Fe, Pb, Cr and Zn are extremely prominent. The magnetic parameters can effectively and quickly reflect the level of particulate matter pollution, making them a useful tool for monitoring urban air quality

Effect of Different Silane Coupling Agents In-Situ Modified Sepiolite on the Structure and Properties of Natural Rubber Composites Prepared by Latex Compounding Method

With the increasing demand for eco-friendly, non-petroleum-based natural rubber (NR) products, sepiolite, a naturally abundant, one-dimensional clay mineral, has been identified as a suitable material for reinforcing NR through the latex compounding method. To create superior NR/sepiolite composites, three silane coupling agents with different functional groups were used to modify sepiolite in situ via grafting or adsorption during the disaggregation and activation of natural sepiolite, which were subsequently mixed with natural rubber latex (NRL) to prepare the composites. The results showed that the modified sepiolite improved the dispersion and interfacial bonding strength with the rubber matrix. VTES-modified sepiolite containing C=C groups slightly improved the performance but retarded the vulcanization of the NR composites, and MPTES and TESPT-modified sepiolites containing -SH and −S4− groups, respectively, effectively accelerated vulcanization, inducing the composites to form a denser crosslink network structure, and exhibiting excellent dynamic and static properties, such as the modulus at a 300% increase from 8.82 MPa to 16.87 MPa, a tear strength increase from 49.6 N·mm−1 to 60.3 N·mm−1, as well as an improved rolling resistance and abrasive resistance of the composites. These findings demonstrate that modified sepiolite can be used to produce high-quality NR/sepiolite composites with enhanced properties

Silanized Silica-Encapsulated Calcium Carbonate@Natural Rubber Composites Prepared by One-Pot Reaction

This article demonstrates the one-pot reaction, an efficient and environmentally friendly organic synthesis method, utilized to prepare the silanized silica-encapsulated calcium carbonate@natural rubber composites (SSC@NR), following first mixing the calcium carbonate (CaCO3) solution, silica (SiO2) sol solution and a small amount of Si-69 solution, to modify the surface of CaCO3 particles, and then wet mixing with natural rubber latex. The obtained silanized silica-encapsulated calcium carbonate (SSC) particles were tested by TGA, FTIR and XRD, to substantiate the effect of surface modification. Moreover, the effects of the amount of SSC on the Mooney viscosity, curing characteristics, physical and mechanical properties and dynamic mechanical properties of the SSC@NR were investigated. The results show that the surface of modified CaCO3 is effectively coated with SiO2 particles by means of physical and chemical combination, to achieve the effect of surface coating. When the optimum amount of SSC filler is 40 phr, the SSC can form better physical adsorption and chemical combination with the NR molecular chains and can be evenly dispersed in the rubber matrix, resulting in the conspicuous improvement of physical and mechanical properties, such as the tensile strength, tear strength, elongation at break and abrasion resistance. Meanwhile, the compound with SSC has preferable processability and dynamic mechanical properties

Interfacial contributions to anomalous Hall effect in perpendicular magnetic anisotropic [Co2MnSi/Pd]3 multilayer

Through engineering the interface between Co2MnSi and Pd, we realize a high perpendicular magnetic anisotropy (PMA) and controllable anomalous Hall effect (AHE) in [Co2MnSi(tCMS)/Pd]3multilayers. The multilayers are characterized by a particulatelike layer morphology following annealing at 573 K with weak B2 crystallographic ordering of the Co2MnSi layer. The largest PMA (Keff) of 1.2x106erg/cm3 has been obtained in [Co2MnSi(1.2nm)/Pd]3 multilayer annealed at 573 K. The AHE can be tuned, which we attribute to a varying proximity effect at the Co2MnSi/Pd interface, by varying the annealing temperature and Co2MnSi thickness. According to the expanded AHE scaling relation, we calculate the different contributions to the origin of AHE. Both skew scattering and side jump decrease monotonically with increasing Co2MnSi thickness, but show maximum values for the multilayer annealed around 573 K with increasing annealing temperature. It is found that skew scattering (ρss) and side-jump scattering (ρsj) exhibit opposite contributions to the AHE; the skew scattering ρss is larger than the value of side jump ∣∣ρsj∣∣, giving a ρss value of approximately 1.34 μΩ cm and the absolute ∣∣ρsj∣∣ value of 1.1 μΩ cm at 5 K in [Co2MnSi(1.2nm)/Pd]3 multilayer, indicating that the overall AHE originates mostly from the skew scattering

Effects of Posttreatments on the Storage Stability of Reclaimed Rubber

Reclaimed rubber should be considered a source of new material with an economic impact, so the recycling of waste rubber is especially important. In this paper, sulfur-cured waste tire rubber powder is successfully devulcanized in a normal-pressure continuous regeneration system under the application of an activator and aromatic oil. Then, the reclaimed rubber was subjected to further mechanical shearing using a two-roll mill, rubber extruder, and rubber strainer. The effects of the storage time at room temperature on the properties and structure of reclaimed rubber were examined by sol fraction measurement, Mooney viscosity measurement, crosslink density measurement, tensile property testing, and Rubber Process Analyzer (RPA) measurement. The results under the test conditions indicated that different postprocessing operations were not making much difference to the properties of the reclaimed rubber. But the effect of storage time is more significant; the Mooney viscosity value increased from 65 to 90 when the storage period increases to 60 days, the sol fraction decreased, and the crosslink and density storage modulus also increased with increasing storage time due to the slow recombination and aggregation of the molecular fragments with free radicals happening in the reclaimed rubber during the storage

Influence of Pyrolytic Carbon Black Derived from Waste Tires at Varied Temperatures within an Industrial Continuous Rotating Moving Bed System

Nowadays, waste tires have emerged as one of the most significant sources of environmental pollution. To address this issue, pyrolysis has become a widely adopted method. The continuous rotary kiln reactor has particularly gained popularity in industrial production for pyrolysis due to its suitability. In order to guide the development of new industrial continuous rotary kiln reactors and achieve high-performance pyrolytic carbon black (CBp), this study was conducted to investigate the relationship between the physical and chemical characteristics of CBp and pyrolysis temperature. The elevated-temperature procedure led to a reduction in DBP values from 90 to 70 mL/100 mg, accompanied by a rise in the specific surface area from 63 to 77 m2/g. The augmentation of pyrolysis temperature was noted to induce the agglomeration of CBp particles, thereby negatively impacting their dispersion within polymer matrices. CBp particles at 550 °C exhibited greater structural order, as determined by Raman spectroscopy, which can be attributed to the elevated temperature proximate to the cylinder wall surface. Furthermore, the potential of CBp for reinforcement in natural rubber (NR) was taken into consideration. The pronounced propensity of high-temperature CBps to agglomerate led to uneven dispersion within the polymer, consequently causing heightened heat accumulation and the emergence of the Payne effect. Based on a thorough analysis of the outcomes, the optimal pyrolysis temperature for CBp synthesis within the continuous reactor was ascertained

Bi-Objective Flexible Job-Shop Scheduling Problem Considering Energy Consumption under Stochastic Processing Times

<div><p>This paper presents a novel method on the optimization of bi-objective Flexible Job-shop Scheduling Problem (FJSP) under stochastic processing times. The robust counterpart model and the Non-dominated Sorting Genetic Algorithm II (NSGA-II) are used to solve the bi-objective FJSP with consideration of the completion time and the total energy consumption under stochastic processing times. The case study on GM Corporation verifies that the NSGA-II used in this paper is effective and has advantages to solve the proposed model comparing with HPSO and PSO+SA. The idea and method of the paper can be generalized widely in the manufacturing industry, because it can reduce the energy consumption of the energy-intensive manufacturing enterprise with less investment when the new approach is applied in existing systems.</p></div