Low-temperature Resistivity Research Articles

Characteristics of the Accessible Chromatin Landscape and Transcriptome under Different Temperature Stresses in Bemisia tabaci.

Bemisia tabaci is an important invasive pest with worldwide distribution and strong temperature tolerance. Previous studies have shown that temperature tolerance varies significantly between the different invasive populations. Several key factors involved in epigenetic regulation have been identified and verified in B. tabaci; therefore, epigenetic adaptation mechanisms may also exist. This study aimed to detect changes in the chromatin accessibility landscape and genome-wide transcriptome under different temperature stresses in B. tabaci. Assay for transposase-accessible chromatin with high-throughput sequencing and RNA-seq analyses indicated that transcriptional activity of the genes strongly correlates with chromatin accessibility. Chromatin transcription-activated gene expression regulation is dominant during high-temperature stress in B. tabaci, mainly through the transcriptional repression of genes related to low-temperature stress resistance. Furthermore, B. tabaci resists low-temperature stress by regulating enzyme activities and withstands high-temperature stress by regulating metabolism and synthesis of organic substances, both achieved by altering chromatin accessibility. In summary, this study provides a theoretical basis for exploring changes in gene expression and chromatin accessibility under different temperature stresses, offering a new approach to unravelling regulatory mechanisms underlying the onset of molecular regulation in response to various temperature stress conditions.

Synergistic Activation of Inert Iron Oxide Basal Planes through Heterostructure Formation and Doping for Efficient Hydrogen Evolution.

Iron oxides have emerged as a very promising and cost-effective alternative to precious metal catalysts for hydrogen production. However, the inert basal plane of iron oxides needs to be activated to enhance their catalytic efficiency. In this study, we employed heterostructure engineering and doped nickel to cooperatively activate the basal planes of iron oxide (Ni-Fe2 O3 /CeO2 HSs) to achieve high hydrogen evolution reaction (HER) activity. The Ni-Fe2 O3 /CeO2 HSs electrocatalyst demonstrates excellent basic HER activity and stability, such as an extremely low overpotential of 43 mV at 10 mA cm-2 current density and corresponding Tafel slope of 58.6 mV dec-1 . The increase in electrocatalyst activity and acceleration of hydrogen precipitation kinetics arises from the dual modulation of Ni doping and heterostructure, which not only modulates the electrocatalyst's electronic structure, but also increases the number and exposure of active sites. Remarkably, the generation of heterogeneous structure makes the catalyst se. The Ni-doped catalyst has not only increased HER activity but also low-temperature resistance. These results suggest that the synergistic activation of inert iron oxide basal planes through heterostructure formation and doping is a feasible strategy. Furthermore, for efficient electrocatalytic water splitting, this technique can be extended to other non-noble metal oxides.

Comprehensive transcriptome and WGCNA analysis reveals the potential function of anthocyanins in low-temperature resistance of a red flower mutant tobacco

The anthocyanin is a protective substance in various plants, and plays important roles in resisting to low-temperature. Here, we explored transcriptome analysis of pink flower (as CK) and the natural mutant red flower (as research objects) under low-temperature conditions, and aimed to reveal the potential functions of anthocyanins and anthocyanin-related regulatory factors in resistance to low-temperature. Our results showed that most of the differentially expressed genes (DEGs) encoding key enzymes in the late stage of anthocyanin metabolism in the mutant were significantly up-regulated. Meanwhile, several genes significantly differentially expressed in CK or mutant were obtained by classification and analysis of transcription factors (TFs), phytohormones and osmoregulators. Additionally, WGCNA was carried out to mine hub genes resistanted to low-temperature stress in flavonoid pathway. Finally, one UFGT family gene, three MYB and one bHLH were obtained as the future hub genes of this study. Combined with the above information, we concluded that the ability of the red flower mutant to grow and develop normally at low-temperatures was the result of a combination of flavonoids and cold resistance genes.

Effect of Basalt Fiber Diameter on the Properties of Asphalt Mastic and Asphalt Mixture.

In this study, basalt fiber having two types of diameters (16 μm and 25 μm) was selected and added to asphalt mastic and asphalt mixtures using different fiber proportions. The influences of fiber diameters and proportions on the properties of asphalt mastic and mixtures were studied. The adhesion behavior of the fiber-asphalt mastic (FAM) interface was evaluated by a monofilament pullout test, and the rheological properties of FAM were evaluated by temperature sweep, linear amplitude sweep, and bending beam rheological tests. In addition, the high-temperature stability, intermediate and low-temperature cracking resistance, and water stability of fiber-modified mixtures were studied by wheel tracking, ideal cracking, a low-temperature bending beam, and a water-immersed Marshall test. The results showed that the interface adhesion behavior between 16 μm fiber and asphalt mastic was more likely in the fiber failure mode at both -12 °C and 25 °C. Adding basalt fiber can significantly improve the high-temperature and fatigue properties of asphalt mastics. Moreover, 16 μm fiber had a better modifying effect on asphalt mastic than 25 μm fiber. The same enhancement trend can be observed in asphalt mixtures. Basalt fibers with 16 μm diameters can improve the high-temperature performance of asphalt mixtures more significantly. In addition, 16 μm fiber could sharply enhance the cracking performance of the mixtures at intermediate and low temperatures, while the enhancing effect of 25 μm fiber on the mixture is insignificant, though both diameters of the fibers have a minor effect on the water stability.

Preparation and microstructural and thermal properties of a vulcanized Eucommia ulmoides gum modified asphalt

In this study, a vulcanized Eucommia ulmoides gum modified asphalt (VEUGMA) was prepared using a natural plant-based renewable rubber Eucommia ulmoides gum (EUG) as the matrix. The preparation process and microstructural and thermal properties of VEUGMA were investigated. The results showed that the optimum shearing time for preparing VEUGMA was 45 min, and the optimum development time was 120 min. Moreover, the EUG dosage follows a monotonically decreasing linear relationship with the optimum sulfur dosage. The VEUGMA exhibited a preferable corrugated network structure, and the vulcanization process of EUG in asphalt can be divided into three stages: slight crosslinking, deep crosslinking, and supreme crosslinking. The X-ray diffraction pattern displayed that only new diffraction peaks of ZnO appeared in the VEUGMA, and the EUG and asphalt exhibited better compatibility under the action of vulcanization aids. After EUG was vulcanized in asphalt, the aromatic ring hydrogen in the asphalt was replaced by aliphatic chains. The VEUGMA exhibited a lower glass transition temperature that suggests a better low-temperature crack resistance. Two maximum decomposition temperatures were noted in the thermal decomposition process of VEUGMA. Moreover, the main gases released were CO2, CO, CH4, SO2, NO2, and NO; of which, CO2 and CO exhibited the highest content, whereas the inferior emissions of SO2, NO2, and NO, can be ignored. The VEUGMA can effectively reduce the release of CO2 and CO but has no significant effect on the release of CH4. Further, VEUGMA demonstrated a smaller storage modulus (E'), loss modulus (E”), and loss factor (tanδ), which suggested better flexibility at low temperatures. Therefore, this work demonstrated the preferable modification effect achieved by adding 3.5 wt% EUG and 6 phr (parts per hundred parts of resin) sulfur to the matrix asphalt.

Research on low-temperature and fatigue properties of recycled asphalt based on the stability of the micelle structure

The research is focused on the asphalt colloid system and provides a detailed analysis of why the effective recovery of low-temperature performance and fatigue performance is challenging during the regeneration of aged asphalt. This study initially examined the alterations in the stability of colloidal structures and micelle structures while rejuvenating aged asphalt. These were performed through four-component analytical tests and asphaltene-resin (A-R) adsorption experiments, respectively. Subsequently, the impact of the regeneration process on the low-temperature performance and fatigue performance of aged asphalt was assessed using bending beam rheometer (BBR) tests and linear amplitude sweep (LAS) tests, respectively. In addition, linear regression analysis was employed to determine the relationship between the stability of colloidal and micelle structures and the performance of recycled asphalt in terms of low-temperature and fatigue resistance. The results show that regeneration of aged asphalt results in 100% recovery of colloidal structural stability, while the maximum recovery of micelle structural stability is only 68.2%. The stability of the micelle structure in recycled asphalt is primarily influenced by the proportion of aged asphalt to virgin asphalt. When the mass ratio of aged asphalt to virgin asphalt is 2:8, the stability of the micelle structure can be restored to 58.1%. However, when the mass ratio is reversed to 8:2, the stability of the micelle structure can only be restored to 21.6%. The impact of the regeneration agent on the recovery of micelle structure stability is minimal. Out of all the samples that underwent regeneration, the highest level of enhancement in the stability of the micelle structure achieved by the rejuvenators was approximately 15%. Linear regression analysis showed that the low-temperature performance of recycled asphalt was significantly affected by the stability of the colloid and micelle structure. The fatigue performance of recycled asphalt was only significantly affected by the stability of the micelle structure. Therefore, enhancing the stability of the micelle structure in recycled asphalt can effectively improve its low-temperature and fatigue performance. This study provides valuable insights into the underlying factors contributing to the subpar low-temperature and fatigue performance of recycled asphalt. Moreover, it contributes to the development of more effective rejuvenators for aged asphalt recycling.

Evaluation of quantum dot composite graphene /Titanium oxide enhanced UV aging resistance modified asphalt

The long-term ultraviolet radiation of asphalt pavement leads to performance degradation, which seriously affects the service life. However, inorganic nanoparticles as anti-ultraviolet aging modifiers can only respond to some ultraviolet light, resulting in not high absorption rate of ultraviolet light. In this study, a variety of nano-quantum dots were introduced to modify graphene/titanium dioxide to further improve the ultraviolet absorption capacity of inorganic nanoparticles and slow down the aging of asphalt pavement caused by ultraviolet light. The effect and mechanism of the special heterojunction structure formed by a variety of quantum dots on the aging resistance and rheological properties of asphalt were investigated. The results show that the introduction of various quantum dots improves the ultraviolet absorption capacity of nano-TiO2. Although the thermal stability of nanographene/titanium dioxide composites decreases, its initial decomposition temperature is much higher than the test temperature of the asphalt mixture. From the macroscopic rheological test, the nano-graphene / titanium dioxide composite material further expands the improvement effect on the high-temperature rheological properties of asphalt, and secondly slows down the low-temperature crack resistance of nano-TiO2 modified asphalt. From the microscopic test, the introduction of various quantum dots greatly reduces the sulfoxide index (SI), carbonyl index (CI) and root mean square roughness Sq of modified asphalt, effectively slowing down the aging effect of ultraviolet light on asphalt, and ensuring the service state of asphalt pavement in a complex environment.

Effects of Environment-Friendly Rejuvenator on the Rheological Properties and Microstructure of Aged Asphalt

The purpose of this paper is to explore the feasibility of using waste soybean oil and the multi-epoxy compound trimethylolpropane triglycidyl ether (TMPGE) compound as a rejuvenator to recycle aged styrene-butadiene-styrene (SBS)-modified asphalt, and to develop an environment-friendly SBS-modified asphalt rejuvenator (ESMAR) to achieve dual waste reuse. The optimum ratio of each component of ESMAR and the production conditions of the formulation were firstly determined by the orthogonal test method. To evaluate the rejuvenation effect of ESMAR, the physical properties and rheological properties of SBS-modified asphalt before and after rejuvenation were studied. Physical properties test results showed that ESMAR can effectively soften the aged asphalt and decrease its softening point and viscosity, as well as increase its needle penetration. As far as rheological properties are concerned, ESMAR could improve the low-temperature cracking resistance and fatigue resistance of aged SBS-modified asphalt; however, there was a certain reduction in the rutting resistance. The microscopic characteristics of the rejuvenation of ESMAR were analyzed by fluorescence microscopy, infrared spectroscopy, and gel permeation chromatography tests for the aged SBS-modified asphalt before and after rejuvenation, which showed that ESMAR can not only reconstruct the degraded SBS molecules in the aged SBS-modified asphalt, but also has a “dilution” effect on the aged asphalt.

Performance Evaluation of Asphalt Concrete Incorporating Steel Slag Powder as Filler under the Combined Damage of Temperature and Moisture

Recycling steel slag into asphalt concrete is an important way to save natural resources and protect the environment. The high asphalt absorption and adsorption and the sensitivity of steel slag aggregate (SSA) to the combined damage of temperature and moisture (volume expansion and poor durability under freeze-thaw cycle damage) still pose risks for the use of SSA in asphalt concrete. It is urgent to develop new utilization methods of steel slag. With this in mind, the material properties of steel slag powder (SSP) and performance characteristics of asphalt concrete incorporating SSP filler were evaluated in this research. The SSP was prepared in the laboratory by grinding steel slag with a particle size of 2.36–4.75 mm. Firstly, the material properties of SSP including the specific surface area, particle gradation, apparent density, chemical compositions, and thermal stability were analyzed. Steel slag (2.36–4.75 mm) and common limestone powder (LP) filler were used as control groups. The grindability of steel slag and the advantages of using SSP as a filler in asphalt concrete were preliminarily analyzed based on the test results of material properties. Then, the Superpave method was used to design asphalt concrete incorporating SSP and LP. Considering that steel slag is sensitive to the combined damage of temperature and moisture, the main engineering performance of asphalt concrete after the combined damage of temperature and moisture was evaluated to further reveal the feasibility of using SSP as a filler. Two combined damage modes, namely hot water damage and freeze-thaw cycle damage, were applied. Results suggest that although the steel slag is more difficult to grind compared to limestone particles, grinding steel slag into SSP has improved the uniformity of its material properties. Good uniformity of material properties, high alkalinity, and excellent thermal stability of SSP give it some advantages in its application in asphalt concrete. Although the freeze-thaw cycle damage has a slightly more significant effect on the engineering performance of asphalt concrete than hot water damage, compared to the asphalt concrete with LP filler, even after freeze-thaw cycle damage for three cycles asphalt concrete incorporating SSP still possesses comparable or better volume stability, mechanical performance, high-temperature deformation resistance, low-temperature crack resistance, fatigue crack resistance, and fatigue durability.

Experimental investigation on the preparation and surface treatment of biomass fibers for stone mastic asphalt mixtures modification

With the sustainable development of infrastructure construction materials, the use of renewable biomass resources in asphalt mixtures could contribute to better sustainability. The bamboo fibers and corn straw fibers with lengths ranging from 1.5 to 12 mm were produced in the laboratory through the proposed crushing, steaming, and grinding processes. A surface treatment with the phenolic resin copolymer modifier was utilized to reconstruct the micro-surface of biomass fibers. The surface treatment effectively reduced the oil absorption multiplier and mass loss of proposed biomass fibers by about 0.6 and 2 %, respectively. The FI-IR absorption peak and change of micromorphology also validated the effective surface reconstructive. Afterward, the virgin asphalt (70#) mixtures and SBS-modified asphalt mixtures with/without biomass fibers were produced for road performance tests and fatigue resistance tests. The results showed that the proposed biomass fibers contributed to about 20 % to 30 % improvement in the high-temperature performance, while the low-temperature cracking resistance was also obviously increased. In addition, the moisture damage resistance and fatigue life were also improved after the addition of biomass fiber modifier, in which the residual stability and tensile strength ratio were increased by about 9 % and 6 % by comparing that with fibreless mixtures, respectively. By comparing the effect of different types and lengths of fiber modifiers, the long bamboo fiber with surface treatment represented the optimized strengthening efficiency. The enhancement mechanism of proposed biomass fiber modifiers was revealed through the microstructure observation. The feasibility of using proposed biomass fibers with surface treatment for producing high-performance SMA has been verified, which can be utilized in the field application for replacing the lignin fiber modifiers for achieving better sustainability.

Cascade phase change from highly-ordered salt hydrate composite monolith for Li-ion battery low-temperature resistance enhancement

The rapid growth of electric vehicles raises an unmet need to enhance low temperature resistance of Li-ion battery (LIB). Herein, highly-ordered and porous boron nitride/polyvinylalcohol (BN/PVA) via directional freeze-drying is fabricated to impregnate with sodium sulfate decahydrate (SSD). The highly-ordered SSD@BN/PVA (HSBP) that is flexible, mechanically strong and electrically insulated possesses high latent heat and leakage-proof temperature. Being inspired by the traditional nucleation theory, a multi-layer structure with gradient freezing points (f.p.s) was built based on HSBP composite along the highly-ordered direction to achieve cascade solidification and controllably thermal energy release. The highly-ordered structure enhances thermal conductivity by 30 times and largely reduces heat dissipation in layers interface. By studying vital factors as solidified heat, f.p. gradient and layer number, a mechanism for cascade solidification is proposed and trilayer HSBP monolith with 3 °C f.p. gradient is proven to be effective for controllable heat release. Consequently, cascade solidification from the multi-layer HSBP monolith could increase temperature holding time by 70 min when battery stops working at −20 °C and improve discharge capacity by 0.71 Ah during cold-start. Therefore, cascade phase change from the multi-layer HSBP monolith shows a significant potential in improving low-temperature resistance of LIB.

Design optimization and performance evaluation of metakaolin-based geopolymer filled porous (semi-flexible) asphalt mixture

This study was conducted to enhance the mixture design proportions and performance of metakaolin based geopolymer (MKG) filled porous asphalt concrete (MKGAC) mixture. The optimum dosage contents of various admixtures, namely fly ash, fine sand, expansion agent, and coupling agent, were determined based on the laboratory evaluation of the mechanical, shrinkage, and fluidity properties of the modified MKG. Additionally, scanning electron microscope (SEM), energy spectra, X-ray diffraction (XRD), and surface free energy measurements were also conducted to characterize the morphological structure and interfacial bonding of the basic (unmodified) and modified MKGAC. In the study, the solid content of the basic MKG was varied within a range of 26%–32%, with 30% determined as the optimum content for maximizing workability and performance characteristics, namely fluidity, shrinkage resistance, low-temperature cracking resistance, moisture resistance, high-temperature stability, and fatigue-crack resistance potential. Based on the high-temperature stability, fatigue, low-temperature cracking, and moisture resistance evaluations, 30% fly ash, 40% fine sand, 6% HCSA expansive agent, and 1.25% KH550 coupling agent were recommended as the optimum admixture contents for modifying and maximizing the performance of MKGAC. The SEM, energy spectra, and XRD analyses, on the other hand, showed that the microstructure and morphological compositions of the geopolymer (MKG) were uniformly consistent after modification with the admixtures. Lastly, it was also quantitatively observed that the interfacial energy between the geopolymer and asphalt-binder matrix increased after adding the admixtures, indicating an enhancement in the adhesive bond strength between the geopolymer (MKG) and the asphalt-binder matrix.

Effect of aging on the low-temperature performance of fiber-reinforced asphalt mixtures

To study the effect of aging on the low-temperature crack resistance of fiber asphalt mixes, three kinds of fibers (lignin fiber, polyester fiber, and basalt fiber) were dry blended into AC-13 asphalt mixes to prepare unaged, asphalt aged (that is, the original asphalt material is subjected to aging treatment), short-term aged, and long-term aged fiber reinforced asphalt mixes. Semicircular bending (SCB) tests and scanning electron microscopy tests were used to analyze and study the effects of aging time and fiber type on the low-temperature properties of asphalt mixtures at an ambient temperature of −5 °C. The SCB test results indicated that: with the deepening of aging, the fracture toughness and fracture energy of the fiber asphalt mixture specimens will tend to decrease, and the aging of the original asphalt has a greater impact on the specimens without fiber; there was great variability in the effect of lignin fibers on the crack resistance of the mix, but it could be a good promoter in unaged asphalt mixes; polyester fiber is the material of choice for improving low-temperature crack resistance in long-term aging pavements; the incorporation of basalt fiber greatly enhances the crack resistance of asphalt mixes and is an excellent material for improving aging asphalt mixes. It is clearly seen by the scanning electron microscope test that with the deepening of aging, the adhesion of asphalt and aggregate gradually deteriorates, and even more so, there is the phenomenon of fine aggregate flaking, and the fiber cannot play an excellent role in reinforcement and crack resistance.

Synthesis of block copolymer with cis-1,4-polybutadiene and isotactic-rich polystyrene using α-diimine nickel catalysts.

A series of styrene-butadiene di-block copolymers with high cis-1,4 unit content (greater than 92%) polybutadiene (PB) and isotactic-rich polystyrene (PS) (mmmm > 65%) was synthesized using α-diimine nickel catalysts (Ni-diimine). Four different Ni-diimine catalysts were synthesized via a complexing reaction between nickel (II) naphthenate and laboratory-made α-diimine ligands L1, L2, L3 and L4, which have different steric volume structures. The results indicate that the Ni-diimine catalyst prepared using the L4 ligand with a higher steric volume can effectively initiate the block polymerization of butadiene and styrene, and the resulting polymer has distinguished cis-1,4 structure unit PB and high isotactic-selective PS block. Differential scanning calorimetry and electrochemical performance tests show that these block copolymers with cis-1,4-regulated and isotactic-selective polymerization have advantages in terms of high-temperature and low-temperature resistance as well as corrosion resistance. Therefore, these copolymers are expected to be widely used in some harsh industrial environments.

Characteristics of waste dry battery powder and its enhancement effect on the physicochemical properties of asphalt binder

The rationalized recycling of waste dry batteries is of great significance to the circular development of resources. In this research, the feasibility of using waste dry batteries in asphalt modification was discussed. Waste dry battery powder (WDBP) was extracted from discarded zinc-manganese dry batteries, and its composition, micromorphology and heavy metal emissions were characterized. Further, the modified asphalts with different WDBP contents were also prepared, and the enhancement effect of WDBP on the physicochemical properties of the binder was evaluated. The results indicate that WDBP mainly contains inorganic carbon and metal oxides. Under acid rain and neutral environment, the heavy metals from WDBP are mainly Zn, Mn and Cd, and their concentrations exceed the concentration limits of Class I surface water in China. The heavy metals in WDBP can be physically solidified for the use of WDBP in asphalt modification. Meanwhile, WDBP can enhance the flow deformation resistance of the binder at the medium-high temperatures, further improve its rutting resistance. However, the WDBP may be have adverse impact on the low-temperature cracking resistance of asphalt, and the WDBP modified asphalt (WDBP-MA) is more suitable for the application in the areas with heavy traffic and hot climate. In addition, the WDBP can enhance the aging resistance of asphalt. Overall, the conclusions confirm the feasibility of applying WDBP to asphalt modification, which can provide a new approach for rational recycling of waste batteries and development of modified asphalt.

Development and Performance Evaluation of an Asphalt Regenerant Derived from Waste Engine Oil Residue.

This study assessed the fundamental physical properties and chemical composition of three specific waste engine oil residue (WEORs) asphalt regenerants. Through dynamic shear rheometer and rolling thin-film oven tests, the performance of aged asphalt was evaluated using three key indicators. Thin-layer chromatography investigations probed the WEOR-induced changes in the aging asphalt components, leading to the creation of two novel asphalt regenerants, WEOR-H and WEOR-G. WEOR-G was developed from WEOR-1, liquid rubber, ultraviolet absorber, light shielding agent, and antioxidant, while WEOR-H was formulated from WEOR-2, aromatic oil, and liquid rubber. The study employed differential scanning calorimetry and conventional laboratory tests to analyze the road performance attributes of Ingevity J type regenerant (J), WEOR-G, and WEOR-H. The results indicated that WEORs increase the saturate and aromatic content in asphalt and partially replenish the missing lightweight components of aged asphalt, moderately improving the three key indicators, though the regenerative effect is restricted. Achieving a full restoration of component proportions within aged asphalt to their initial levels proved unattainable, and direct application of any of the three WEORs as asphalt regenerants is impractical. WEOR-H and WEOR-G demonstrated potential in enhancing aged asphalt binder road performance, outpacing three other WEORs. At a 14% dosage, WEOR-G and WEOR-H could increase the 10 °C ductility to 23.5 and 21.4 cm, respectively, effectively counterbalancing the insufficient ability of WEOR-1 and WEOR-2 to restore the low-temperature performance of aged asphalt. Among the regenerants, WEOR-G, possessing superior regenerative effects, the lowest glass transition temperature, and optimal low-temperature deformation resistance, emerged as the most efficacious. This inquiry furnishes vital data support for future applications of WEOR-G asphalt regenerant.

Investigation on physical properties and modification mechanisms of diatomite/SBR modified asphalt.

In recent years, diatomite has been successfully adopted in asphalt modification to overcome the problems of polymer modified asphalt, because of the advantages in wide sources, low price, and worthy technical characteristics. Although the improvement of the high-temperature performance of the modified diatomite asphalt has been verified in previous studies, the diatomite will bring negative impact on the low-temperature resistance. Hence, the objective of this study is to seek a new channel to improve the comprehensive performance of the diatomite modified asphalt binder. Considering the advantage of the SBR in improving the low-temperature performance of asphalt binder, the diatomite/SBR composite modified asphalt binder (DSA) and the corresponding preparation technology are developed to obtain an improved comprehensive performance via the orthogonal experiment method in this study. Moreover, the modification mechanisms of the DSA are revealed using fluorescence microscopy (FM) tests, Gel permeation chromatography (GPC) tests, and Fourier transform infrared spectroscopy (FTIR) tests.

Improving low-temperature NH3-SCR denitration activity and resistance to H2O and SO2 over Nb-modified NbaSn0.3CeOx catalysts by enhancing acidity to compensate for its weak oxidation ability

In this paper, a series of Nb-modified NbaSn0.3CeOx (a = 0.2, 0.4, 0.5) catalysts for denitrification were prepared using a facile co-precipitation method. In order to explore the various individual properties of the samples, the catalysts were characterized by XRD, Raman, N2 adsorption and desorption, TEM, NH3-TPD, H2-TPR, XPS and in-situ DRIFTS tests to understand the influences of the Nb introduction on the NH3-SCR reaction. Among these catalysts, the Nb0.4Sn0.3CeOx catalyst exhibit excellent NH3-SCR performance in the temperature range of 155–450 °C with more than 90 % NO conversion, 100 % N2 selectivity, and possess good resistance to H2O and SO2. Compared with the Sn0.3CeOx catalyst, we believe that the improvement of the low-temperature NH3-SCR performance of the Nb0.4Sn0.3CeOx catalysts is mainly due to the change in the amount of acid, special for the increase in B acid content, which compensates for the effect of the weaken oxidizing ability on the low-temperature activity. Beyond that, the good H2O and SO2 resistance at low temperature after the introduction of Nb into Nb0.4Sn0.3CeOx catalysts was analyzed by using in-situ DRIFTS characterization in detail, and the results indicate that the incorporation of Nb can inhibit the oxidation of SO2 to form sulfate on the catalysts, and prevent the competing adsorption of H2O and NOx, but the adsorption of NH3 is not affected. This work proves that the acidity regulation can improve low-temperature SCR activity by the synergistic effect between oxidation capacity and acidity.

Innovative Use of Waste PET-Derived Additive to Enhance Application Potentials of Recycled Concrete Aggregates in Asphalt Rubber.

Polyethylene terephthalate (PET) drinking bottles, rubber tires, and concrete are the very common municipal solid wastes, which are usually disposed of at landfills and stockpiles and cause continuous damage to the environment. Some studies have indicated that waste PET can be chemically converted into an additive for improving the overall properties of asphalt pavement incorporating natural aggregates, especially the moisture-induced damage resistance. However, it is not clear whether this PET additive still works for asphalt rubber containing recycled concrete aggregates (RCA). To well reveal this issue, this study first adopted a similar way to chemically recycle waste PET into the additive for modifying crumb rubber modified asphalt (CRMA) binder and then mixed the binder with the 13 mm maximum aggregate stone matrix asphalt containing 100% coarse RCA for preparing the mixtures. After a series of physicochemical characterizations of the PET additive, the moisture resistance, rutting resistance, low-temperature cracking resistance, and fatigue resistance of the mixture were systematically evaluated. The results showed that the PET additive is capable of improving the resistance to moisture and high-temperature deformation of asphalt rubber and helps greatly reduce the moisture-induced damage to the interfacial bonding layer. To be more detailed, the residual Marshall stability (RMS) value of RCA-CRMAM/1PET after 72 h of immersion is higher than 85% by contrast to that of RCA-CRMAM (77.1%), while the tensile strength ratio (TSR) value of RCA-CRMAM/1PET shows more than 80% compared to that of 65.2%. In addition, only 1% PET additive can enhance the high-temperature resistance of asphalt rubber containing RCA to rut and allow it to maintain higher resistance to rut after moisture-induced damage. 1% PET additive can help improve the bearing capacity of RCA-CRMAM under a low-temperature environment and delay its fatigue life at small stresses. Generally, with the successful introduction of PET additives to asphalt rubber containing RCA, more durable and sustainable highway pavement can be produced and applied in practice to alleviate the negative impacts caused by waste PET, waste tire rubber, and waste concrete.

Study on properties and application of chloroprene rubber/polyurethane modified asphalt sealant

Under the long-term effect of loads and climate conditions, various diseases can appear on the surface of asphalt pavement, causing deterioration in its performance. To address the pavement surface cracks during service, the present study developed a crumb rubber/polyurethane (CR/PU) compound as the modified asphalt sealant with excellent properties. The optimal material proportion, ensuring the best asphalt compatibility was selected to meet the requirements of standard hot-poured sealants for pavement. Additionally, the fineness and content of CR were determined. The research investigated rheological properties, aging performance, microstructure, and modification mechanism of the CR/PU sealant was then applied in an engineering project to evaluate its effectiveness in treating pavement cracks, and suitable construction techniques were summarized. The results revealed that the in-situ polymerization method is an appropriate approach for preparing the CR/PU sealant, demonstrating good high-temperature deformation resistance and low-temperature crack resistance, indicating synergistic interactions between CR and PU. Among various compositions, the sealant with 30 %PU and 15 %CR content exhibited the best thermal oxygen and UV aging properties. Microscopic tests indicated that CR was physically blended with asphalt, while PU underwent chemical modification and formed a cross-linked network structure with asphalt, resulting in CR dispersion around it, enhancing the thermal stability of the system. Furthermore, the test section displayed an ideal crack treatment effect, demonstrating the sealant’s excellent sealing, durability, and watertight capacity.