The Workability and Mechanical Performance of Fly Ash Cenosphere-Desert Sand Ceramsite Concrete: An Experimental Study and Analysis.

In order to alleviate the shortage of sand resources for construction, make full use of industrial waste and promote the development of green lightweight aggregate concrete in the desert and surrounding areas, this paper proposes a new lightweight ceramsite concrete, fly ash cenospheres and desert sand ceramsite concrete (FDCC). An orthogonal test was conducted to analyze the effects of the desert sand (DS) replacing ratio, fly ash cenosphere (FAC) replacing ratio and polymer emulsion (PLE) addition on the damage patterns, slump, apparent density and compressive strength of the FDCC. The results showed that the most influential factors for the slump, apparent density and compressive strength of the FDCC were the FAC replacing ratio, FAC replacing ratio and DS replacing ratio, respectively. Meanwhile, the PLE addition had little effect on the workability or mechanical performance of the FDCC. With the increase in the DS replacing ratio, the slump decreased rapidly and the compressive strength reached its peak value, increasing by 20.6% when the DS replacing ratio was 20%. With the increase in the FAC replacing ratio, the slump increased by 106%, the apparent density decreased gradually and the compressive decreased and then increased, reaching its lowest value when the FAC replacing ratio was 20%. According to the synthetic evaluation analysis, the optimum DS replacing ratio, FAC replacing ratio and PLE addition of the FDCC were 20%, 30% and 1%, respectively.

Diagnostic value of congenital pulmonary airway malformation volume ratio for fetal hydrops due to congenital lung malformations: a systematic review and meta-analysis.

OBJECTIVE: Meta-analysis was used to evaluate the diagnostic value of a CVR cut-off value of 1.6 for fetal hydrops due to congenital lung malformation (CLM). METHODS: A systematic search of PubMed, Embase, Web of Science, CNKI, VIP, and Wanfang published before 7/30/2021 for the value of a congenital pulmonary airway malformation volume ratio (CVR) cut-off value of 1.6 for the diagnosis of fetal hydrops. According to the inclusion and exclusion criteria, the literature that met the requirements were obtained. A total of 75 articles were retrieved, and 12 articles were included for further analysis. The quality of these studies was evaluated according to the Quality Assessment for Studies of Diagnostic Accuracy tool (QUADAS-2) criteria. The Q test and heterogeneity I2 were used to evaluate the heterogeneity due to non-threshold effects, and Stata 15.0 was used for statistical analysis to evaluate the diagnostic value of the CVR cutoff value of 1.6 for fetal hydrops due to CLM. RESULTS: A total of 12 studies were included. The QUADAS-2 indicated that the risk of bias was relatively low, and the clinical applicability was relatively high. Statistical analysis was performed on included studies using a random effect model. Meta-analysis showed that the pooled sensitivity, specificity, diagnostic ratio and summary receiver operating characteristic (SROC) for the diagnosis of fetal hydrops by CVR were 0.86 (95% CI, 0.72-0.93; I2 = 59.84), 0.90 (95% CI, 0.88-0.93; I2 = 31.94), 58 (95% CI, 22-149; I2 = 100%), 0.93 (95% CI, 0.91-0.95). CONCLUSIONS: The sensitivity and specificity of CVR cut-off value 1.6 for the diagnosis of CLM-induced fetal hydrops were high, no publication bias was observed, and the CVR cut-off value 1.6 is meaningful for the early diagnosis prediction of CLM-induced fetal hydrops.

Synthesis of styrene maleic anhydride copolymer grafted graphene and its dispersion in aqueous solution.

In this study, three simple methods were described to synthesize covalently functionalized graphene nanoplatelets (GNPs) with poly(styrene-co-maleic anhydride) (SMA) via ester linkages. Furthermore, the dispersibility of modified GNPs in aqueous solution was characterized by several techniques. Anchoring of SMA long-chains on GNPs via chemical bonds was confirmed by Fourier transform infrared spectroscopy. Furthermore, field emission scanning electron microscopy analysis indicated that the SMA unevenly covered the surface and edges of the GNPs. Solubility measurements showed that the modified GNPs prepared by the designed method had excellent dispersibility in aqueous solution, and the grafting rate of modified GNPs showed an obvious positive correlation with the concentration in aqueous solution as revealed by ultraviolet absorbency and thermogravimetric analysis results. Markedly, the modified GNPs during ultrasonic treatment exhibited better dispersibility and grafting rate compared to others. Moreover, the experimental results confirmed that GNP concentration reached up to 0.32 mg mL-1 in aqueous solution and the grafting rate was 18.02%. The content of SMA had little effect on grafting rate; however, the ultrasonic duration significantly affected the process.