Effect of Thermal Oxygen Aging Mode on Rheological Properties and Compatibility of Lignin-Modified Asphalt Binder by Dynamic Shear Rheometer

Lignin is abundant in nature. The use of lignin in the asphalt pavement industry can improve pavement performance while effectively optimizing pavement construction costs. The purpose of this paper is to study the effect of lignin on the anti-aging properties of asphalt. Commercial lignin was selected to prepare a lignin-modified asphalt binder. The properties of lignin-modified asphalt were studied by rheological experiments. The high-temperature rheological properties of two kinds of base asphalt and modified asphalt samples with different contents of lignin under three conditions of original, rolling thin film oven (RTFO) aging, and pressure aging vessel (PAV) were tested and analyzed with temperature sweep, frequency sweep, and multiple stress creep recovery (MSCR) tests. By comparing the variation laws of evaluation indicators, such as complex shear modulus G*, phase angle δ, anti-aging index, cumulative strain, and viscous component Gv, we found that lignin could effectively improve the high-temperature stability of base asphalt, but it had a negative impact on the compatibility issues of base asphalt. Meanwhile, lignin played a filling role in the base asphalt, and the increase in viscosity was the fundamental reason for improving the high-temperature stability of the base asphalt. The research results indicated that lignin could effectively improve the anti-aging performance of asphalt and play a positive role in prolonging the service life of pavement

Characterization and Fungicide Screening of a New Pathogen That Causes Leaf Spot on <i>Rehmannia glutinosa</i>

Outbreaks of leaf spot disease occurred in Rehmannia glutinosa fields in Henan Province, China, in 2019, with the incidence ranging from 20% to 40%. R. glutinosa plants with diseased leaves were collected, and 25 isolates were obtained. Pathogenicity tests, morphological observations, and phylogenetic analyses were conducted to identify the pathogens, and the biological characteristics and control agents of the pathogens were studied. Five isolates of pathogenic fungi were isolated. Three isolates were identified as Fusarium equiseti, which is a new pathogen causing R. glutinosa leaf disease; the other two isolates were identified as Fusarium acuminatum. The mycelia of F. equiseti grew fastest on Czapek medium, and the optimal temperature and pH were 25 °C and 10.0, respectively. The mycelia of F. equiseti grew from 5 °C t o 35 °C, and the lethal temperature was 55 °C. The optimal carbon and nitrogen sources were soluble starch and peptone, respectively. Eight fungicides had inhibitory effects on the mycelial growth of F. equiseti and F. acuminatum. Prochloraz had higher activities against F. equiseti and F. acuminatum, with EC50 values of 0.139 mg·L−1 and 0.123 mg·L−1, respectively. These results provide useful information that will aid the development of management strategies to control leaf diseases of R. glutinosa caused by F. equiseti and F. acuminatum.</i

Characterization and Fungicide Screening of a New Pathogen That Causes Leaf Spot on Rehmannia glutinosa

Outbreaks of leaf spot disease occurred in Rehmannia glutinosa fields in Henan Province, China, in 2019, with the incidence ranging from 20% to 40%. R. glutinosa plants with diseased leaves were collected, and 25 isolates were obtained. Pathogenicity tests, morphological observations, and phylogenetic analyses were conducted to identify the pathogens, and the biological characteristics and control agents of the pathogens were studied. Five isolates of pathogenic fungi were isolated. Three isolates were identified as Fusarium equiseti, which is a new pathogen causing R. glutinosa leaf disease; the other two isolates were identified as Fusarium acuminatum. The mycelia of F. equiseti grew fastest on Czapek medium, and the optimal temperature and pH were 25 &deg;C and 10.0, respectively. The mycelia of F. equiseti grew from 5 &deg;C t o 35 &deg;C, and the lethal temperature was 55 &deg;C. The optimal carbon and nitrogen sources were soluble starch and peptone, respectively. Eight fungicides had inhibitory effects on the mycelial growth of F. equiseti and F. acuminatum. Prochloraz had higher activities against F. equiseti and F. acuminatum, with EC50 values of 0.139 mg&middot;L&minus;1 and 0.123 mg&middot;L&minus;1, respectively. These results provide useful information that will aid the development of management strategies to control leaf diseases of R. glutinosa caused by F. equiseti and F. acuminatum