Microplastic release and sulfate reduction response in the early stage of a simulated landfill.

Landfills are essential facilities for treating and disposing municipal solid waste. They emit sulfur-containing odors and serve as an important sink for a new type of pollutant called microplastics (MPs). This study focused on the initial stage of anaerobic degradation to establish the relationship between the release of MPs and odor generation. Our findings show the rapid release of MPs into the leachate in the early stage of landfill and their predominant accumulation in the leachate sediment. The circulating leachate contained 1.45 times higher concentrations of MPs than the noncirculating leachate, with a peak concentration of 39 items·L-1. In addition, fragmentation of MPs occurred. The percentage of MPs with particle sizes of 2.5-5 mm decreased from 66.70 % to 22.32 %, while those measuring 0.1-0.5 mm increased by 33.12 %. A positive correlation was observed between MP release and sulfate reduction. Although leachate circulation increased the release of MPs, it also reduced the overall release time and total amount of MPs exported from the landfill. Compared with the initial landfill waste, the leachate operation mode, regardless of circulation, resulted in a 6.15-8.93-fold increase in MP release. These findings provide a valuable foundation for the simultaneous regulation of traditional pollutant odor and new pollutants (MPs) in landfills.

Adhesion between Asphalt and Recycled Concrete Aggregate and Its Impact on the Properties of Asphalt Mixture.

To study and evaluate the adhesion between recycled concrete aggregate and asphalt, the contact angles (CAs) between droplet (water and ethanol) and recycled concrete aggregate (RCA), natural aggregates, and solid bitumen (matrix asphalt, SBS modified asphalt) were tested via the sessile drop method with an optical microscope. The surface free energy was then calculated. The CAs between hot asphalt and RCA and natural aggregates were tested via the hanging slice method. The adhesive energy between asphalt and RCA and natural aggregates were calculated based on the test results of the surface free energy and CAs. Then, the influence of RCA on the water stability and fatigue performance of the asphalt mixture was analyzed by testing the water stability and fatigue properties of hot mix asphalts containing RCA (HMA-RCA) with different aggregates and RCA dosages. The surface energy of the various aggregates and the CAs between aggregates and asphalts were sorted as follows: Granite > RCA > serpentinite > limestone. The surface energy and CA of RCA were very close to that of serpentinite. The adhesive energy between various aggregates and asphalt were sorted as follows: Limestone > serpentinite > RCA > granite. The adhesive energy between RCA and asphalt was also very close to that of serpentinite. The residual Marshall stability, tensile strength ratio, and fatigue performance of the HMA-RCAs were gradually reduced along with the increasing RCA dosage. This effect may be attributed to the fact that the adhesive energy between the RCA and the asphalt was less than that of water and that the asphalt was easily stripped from the RCA surface. Excessive RCA content in the aggregate can lead to excessive porosity of the HMA-RCA. The CAs and adhesive energy between RCA and asphalt showed significant effects on the water stability and fatigue performance of HMA-RCA.

[Clinicopathologic and radiologic features of dysembryoplastic neuroepithelial tumors].

OBJECTIVE: To study the clinicopathologic features and radiologic findings of dysembryoplastic neuroepithelial tumor (DNT). METHODS: The clinical presentations, radiologic findings, histologic features and immunophenotype of 9 cases of DNT were analyzed. RESULTS: The age of patients ranged from 12 to 51 years (mean age = 32 years). Most presented with partial seizures, sometimes accompanied by transient aphasia, agraphia and decreased visual acuity. One case was asymptomatic and discovered incidentally during a routine check-up. All patients had no neurological deficit found on physical examination. All tumors were located in the supratentorial cerebral cortex. There was no peritumoral edema or space-occupying effect on radiologic examination. The tumors involved either frontal lobe (number = 4), temporal lobe (number = 4), frontoparietal lobe (number = 1) . Two cases showed cystic changes. Two histologic variants of DNT were recognized: simple (number = 3) and complex (number = 6). Simple variant was composed mainly of the glioneuronal element, accompanied by surrounding oligodendrocyte-like cells, and the complex variant contained a low-grade glioma component, in addition to the glioneuronal element and sometimes foci of cortical dysplasia. CONCLUSIONS: DNT is a benign tumor with excellent prognosis after surgical excision. Local recurrence is rare. Complex variant of DNT needs to be distinguished from other types of low-grade glioma.