Since the outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, considerable attention has been paid on its epidemiology and clinical characteristics in children patients. However, it is also crucial for clinicians to summarize and investigate the co-infection of SARS-CoV-2 in children. We retrospectively reviewed the clinical manifestations, laboratory findings, and imaging characteristics of COVID-19 patients in co-infection group (CI, n = 27) and single infection group (SI, n = 54). Samples were tested for multiple pathogens. A high incidence (27/81, 33%) of co-infection in children with COVID-19 was revealed. The most frequent co-infected pathogen was mycoplasma pneumoniae (MP, 20/81, 25%), followed by virus (6/81, 7%), and bacteria (4/81, 5%). No significant difference in clinical characteristics, laboratory examinations, or hospital stay was observed between the patients with co-infections and those with monomicrobial, only lower in white blood cell counts (CI: 5.54 ± 0.36 vs SI: 7.38 ± 0.37, P = .002), neutrophil counts (CI: 2.20 ± 0.20 vs SI: 2.92 ± 0.23, P = .024) and lymphocyte counts (CI: 2.72 ± 0.024 vs SI: 3.87 ± 0.28, P = .006). Compared with the patients with monomicrobial, chest imaging of those with co-infections showed consolidation in more cases (CI: 29.6% vs SI: 11.1%, P = .038) and duration of positive in nucleic acid was shorter (CI: 6.69 ± 0.82 vs SI: 9.69 ± 0.74, P = .015). Co-infection was relatively common in children with COVID-19, almost 1/3 had co-infection, most commonly caused by MP. Co-infection did not cause a significant exacerbation in clinical manifestations.
In this reported work, thermoplastic polyurethane (TPU) was used as a reactive polymer modifying agent to prepare a modified-asphalt, using a high-speed shearing method. Physical performance tests of the TPU-modified asphalt were conducted before and after short-term aging, and the aging resistance was examined by the change in materials properties. In addition, low-temperature rheological properties, thermal properties, the high-temperature storage stability, and the aging mechanism of TPU-modified asphalt were also investigated. The results showed that the addition of TPU improved the aging resistance of base asphalt, which was evidenced by the increased penetration ratio and decreased softening point of the asphalt, after aging. Similarly, Fourier Transform infrared (FTIR) spectroscopy results verified that TPU improved the asphalt aging resistance. It was found that the TPU functional groups played a role in improving thermal properties, high-temperature storage stability, and in the dispersion of modified asphalt.
Packaging wastes not only pollute the environment, but also waste resources. In this study, bags of suits made mainly from ethylene(vinyl acetate) copolymer (EVA), as the modifier, were used to improve the properties of raw asphalt. On the basis of the common physical modification, crosslinking agents and catalysts were added to the raw oil asphalt. The modification technologies were studied carefully. The results showed that crosslinking agents and catalysts could make the polymer react with raw asphalt, thus providing chemical connections between them and forming three-dimensional network structures. As a result, the asphalt performance was improved. In addition, the dosages of the crosslinking agent, modification temperature, and time also had effects on the performance of the modified asphalt. When the ratio of divinylbenzene to asphalt was 0.0125, the ratio of catalyst to asphalt was 0.025, the temperature was 1408C, and the modification time was 2.5 h, the softening point of the asphalt rose from 49.58C to 63.58C, and the penetration degree dropped from 68.5 to 39.1 (0.1 mm). The results showed that after the modification with waste EVA, the performance of the asphalt had been significantly improved and stabilized. J. VINYL ADDIT. TECHNOL.,
Waste‐polyethylene (WPE) in packaging, instead of virgin polymer, was utilized as a modifier of base asphalt, and rheological properties of the modified asphalt were studied. Results show that the modified asphalt possesses better anti‐distortion capacity than the base asphalt, as indicated by the fact that the modified asphalt has higher viscosity and smaller endothermic peak dispersion in the transformation process of asphalt aggregation. Compared with base asphalt, the modified asphalt has higher complex modulus (G*), storage modulus (G′), and dissipation modulus (G″). In addition, the modified asphalt has smaller phase angle (δ), less tangent (tanδ), and lower rut factor (G*/sinδ), reflecting the high‐temperature rut resistance of the asphalt. The improvement of the rheological properties is related to the main features of the modified asphalt, including the swelling, whereas packaging‐waste‐PE absorbs low‐molecular‐weight fractions of asphalt, the displacement restriction of asphalt particles, and the molecular structure and performance of PE molecules. J. VINYL ADDIT. TECHNOL., 21:215–219, 2015. © 2014 Society of Plastics Engineers
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