Ground vibration propagation and attenuation of vibrating compaction

When a high-power vibrating roller compact the subgrade, the vibration wave will quickly propagate along the surface of the subgrade and generate hazards to surrounding environment and structure. To study the vibration propagation rules of the roller, the vibration acceleration of the high-power vibrating roller was measured on the surface of the rock subgrade, coarse-grained soil subgrade and fine-grained soil subgrade. The respective relations between vibration acceleration and the distance from a vibration source in the vertical, horizontal radial and horizontal circumferential direction have been discovered. The research results show that the vibration peak frequency generated by the vibrating roller on the subgrade approximates vibration frequency. The vibration effective influence distance varies from 10m to14m, and the horizontal radial vibration is greater than that of vertical and horizontal circumferential direction. The vibration of the rock subgrade attenuates the most slowly and propagates the most remotely

Experimental study on the shear stiffness and damping ratio of the coarse-grained soil against geogrid interface

Geosynthetic-reinforced soil structures are mostly used to retain subgrade slope of highway and railway. For the design and performance analyses of geosynthetic-reinforced soil structures under repeated loading, such as those induced by compaction, traffic and earthquakes, the understanding of cyclic soil–geosynthetic interface behaviour is of great interest. Nevertheless, experimental data concerning this type of behaviour are very scarce. A laboratory study was carried out and is described in this paper. This paper presents the behaviour of an interface between a coarse-grained soil and a geogrid under cyclic loading conditions. A large-scale direct shear test device able to perform displacement-controlled cyclic tests was used. The results obtained are presented and discussed, especially the effects of the displacement amplitude and normal stress on the shear stiffness and damping ratio are investigated. The dynamic response parameters of the soil-geosynthetic interface are greatly affected by the number of cycles, and the variations in the two parameters with the number of cycles are related to the normal stress and the shear displacement amplitude. when at large displacements, the damping ratio decreases first and then stabilizes with the number of cycles. However, at small displacement, the shear stiffness and damping ratio are all decrease somewhat at the initial stage of cyclic shearing. As the experimental materials used in this study are relatively single, and further experimental research should be carried out in the future. The shear parameters of interface in this study can provide reference for the design of reinforced soil structure

Forsythiae Fructus: A Review on its Phytochemistry, Quality Control, Pharmacology and Pharmacokinetics

Forsythiae Fructus, as a traditional Chinese medicine, has been widely used both as a single herb and in compound prescriptions in Asia, mainly due to its heat-clearing and detoxifying effects. Modern pharmacology has proved Forsythiae Fructus possesses various therapeutic effects, both in vitro and in vivo, such as anti-inflammatory, antibacterial and antiviral activities. Up to now, three hundred and twenty-one compounds have been identified and sensitive analytical methods have been established for its quality control. Recently, the pharmacokinetics of Forsythiae Fructus and its bioactive compounds have been reported, providing valuable information for its clinical application. Therefore, this systematic review focused on the newest scientific reports on Forsythiae Fructus and extensively summarizes its phytochemistry, pharmacology, pharmacokinetics and standardization procedures, especially the difference between the two applied types—unripe Forsythiae Fructus and ripe Forsythiae Fructus—in the hope of providing a helpful reference and guide for its clinical applications and further studies

Asperuloside and Asperulosidic Acid Exert an Anti-Inflammatory Effect via Suppression of the NF-κB and MAPK Signaling Pathways in LPS-Induced RAW 264.7 Macrophages

Hedyotis diffusa is a folk herb that is used for treating inflammation-related diseases in Asia. Previous studies have found that iridoids in H. diffusa play an important role in its anti-inflammatory activity. This study aimed to investigate the anti-inflammatory effect and potential mechanism of five iridoids (asperuloside (ASP), asperulosidic acid (ASPA), desacetyl asperulosidic acid (DAA), scandoside methyl ester (SME), and E-6-O-p-coumaroyl scandoside methyl ester (CSME)) that are presented in H. diffusa using lipopolysaccharide (LPS)—induced RAW 264.7 cells. ASP and ASPA significantly decreased the production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in parallel with the inhibition of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), TNF-α, and IL-6 mRNA expression in LPS-induced RAW 264.7 cells. ASP treatment suppressed the phosphorylation of the inhibitors of nuclear factor-kappaB alpha (IκB-α), p38, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). The inhibitory effect of ASPA was similar to that of ASP, except for p38 phosphorylation. In summary, the anti-inflammatory effects of ASP and ASPA are related to the inhibition of inflammatory cytokines and mediators via suppression of the NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways, which provides scientific evidence for the potential application of H. diffusa

Employing Singlet Fission into Boosting the Generation of Singlet Oxygen and Superoxide Radicals for Photooxidation Reactions

Developing highly efficient heavy-metal-free photosensitizers (PSs) for the production of reactive oxygen species (ROS) is urgent to achieve wide applications of ROS, yet it remains a great challenge. As a proof of concept, singlet fission (SF), possessing the exciton multiplication ability with a maximum 200% triplet yield, is employed to generate ROS. Herein, a metal-free tetracene dimer with a high yield (∼164%) of long-lived triplets (>300 μs) is prepared and used to generate singlet oxygen (1O2) and superoxide radicals (O2·–). Remarkably, 1O2 and O2·– yields are boosted compared to the existing traditional PSs based on intersystem crossing (ISC). The 1O2 yield reaches an unprecedented ∼148%, representing the highest value ever reported so far. Thus, this SF PS shows an improved photooxidation activity over ISC PSs. Additionally, the 1O2 and O2·– generation mechanisms are described clearly by combining TA spectra and controlled experiments. This represents the first example of utilizing the two triplet states produced by SF to generate ROS and catalyze related reactions. The work not only presents a strategy for generating and enhancing the 1O2/O2·– yield but also opens up a new field for the application of SF