Leaching Behavior of Heavy Metals from Cement Pastes Using a Modified Toxicity Characteristic Leaching Procedure (TCLP).

As the standard toxicity characteristic leaching procedure (TCLP) can not exhaust the acid neutralizing capacity of the cement rotary kiln co-processing solid wastes products which is particularly important for the assessment of the leaching concentrations of heavy metals. A modified TCLP was proposed. The extent of leaching of heavy metals is low using the TCLP and the leaching performance of the different metals can not be differentiated. Using the modified TCLP, however, Zn leaching was negligible during the first 180 h and then sharply increased (2.86 ± 0.18 to 3.54 ± 0.26 mg/L) as the acidity increased (pH < 6.0). Thus, Zn leaching is enhanced using the modified TCLP. While Pb leached readily during the first 126 h and then leachate concentrations decreased to below the analytical detection limit. To conclude, this modified TCLP is a more suitable method for these cement rotary kiln co-processing products.

A global synthesis of microplastic contamination in wild fish species: Challenges for conservation, implications for sustainability of wild fish stocks and future directions.

Research on the occurrence of microplastics in wild fish populations is a constantly growing area, requiring continuous reviews to properly keep up with the fast pace of publications and guide future work. This review analyses the scientific output of 260 field studies covering 1053 different fish taxa for the presence of microplastics. To date, microplastics have been recorded in 830 wild fish species, including 606 species of interest to commercial and subsistence fisheries. Among these, based on IUCN Red List status, 34 species are globally classified in one of the three threatened categories (Critically Endangered, Endangered or Vulnerable) and another 22 species were assessed as "Near Threatened". Of the species for which the IUCN Red List tracks population trend data, the fish species reported to have microplastics so far include 81 which are recorded as declining, 134 as stable and just 16 as increasing. This review highlights the potential implications of fish microplastic contamination to biodiversity conservation, sustainability of wild fish stocks, and human food safety and security. Finally, recommendations for future research are presented.

Molecular Epidemiology of Plasmid-Mediated Types 1 and 3 Fimbriae Associated with Biofilm Formation in Multidrug Resistant Escherichia coli from Diseased Food Animals in Guangdong, China.

Types 1 and 3 fimbriae in Enterobacteriaceae play versatile roles in bacterial physiology including attachment, invasion, cell motility as well as with biofilm formation and urinary tract infections. Herein, we investigated the prevalence and transmission of plasmid-mediated types 1 and 3 fimbriae from 1753 non-duplicate Enterobacteriaceae from diseased food Animals. We identified 123 (7.01%) strong biofilm producers and all was identified as E. coli. WGS analysis of 43 selected strong biofilm producers revealed that they harbored multiple ARGs, including ESBLs, PMQR and mcr-1. The gene clusters mrkABCDF and fimACDH encoding types 1 and 3 fimbriae, respectively, were identified among 43 (34.96%) and 7 (5.7%) of 123 strong biofilm isolates, respectively. These two operons were able to confer strong biofilm-forming ability to an E. coli weak-biofilm forming laboratory strain. Plasmid analysis revealed that mrk and fim operons were found to co-exist with ARGs and were primarily located on IncX1 and IncFII plasmids with similar backbones, respectively. mrkABCDF operons was present in all of 9457 Klebsiella pneumoniae using archived WGS data, and shared high homology to those on plasmids of 8 replicon types and chromosomes from 6 Enterobacteriaceae species from various origins and countries. In contrast, fimACDH operons was present in most of Enterobacter cloacae (62.15%), and shared high homology to those with only a small group of plasmids and Enterobacteriaceae species. This is the first comprehensive report of the prevalence, transmission and homology of plasmid-encoded type 1 and 3 fimbriae among the Enterobacteriaceae. Our findings indicated that plasmid-encoded mrkABCDF and fimACDH were major contributors to enhanced biofilm formation among E. coli and these two operons, in particular mrk could be as a potential anti-biofilm target. IMPORTANCE Biofilms allow bacteria to tolerate disinfectants and antimicrobials, as well as mammalian host defenses, and are therefore difficult to treat clinically. Most research concerning biofilm-related infections is typically focused on chromosomal biofilm-associated factors, including types 1 and 3 fimbriae of biofilm-forming Enterobacterium. However, the transmission and homology of the mobile types 1 and 3 fimbriae among Enterobacteriaceae is largely unknown. The findings revealed that the plasmid-encoded type 3 fimbriae encoded by mrkABCDF and type 1 fimbriae encoded by fimACDH were major contributors to enhancing biofilm formation among strong biofilm E. coli from diseased food producing animals. Additionally, mrk operon with high homology at an amino acid sequence was present both on plasmids of various replicon types and on chromosomes from diverse Enterobacteriaceae species from numerous origins and countries. These findings provide important information on the transmission of the mobile types 1 and 3 fimbriae among Enterobacteriaceae, indicating a potential antibiofilm target.

Effect of waste addition points on the chromium leachability of cement produced by co-processing of tannery sludge.

The effect of adding position for tannery sludge in a co-processing cement rotary kiln on the chromium leachability of the cement produced was assessed in laboratory scale. Cement clinkers and pastes were produced and evaluated based on analysis of the cement quality, characterization of the clinker crystalline phases, and extraction toxicity of heavy metals in the resulting cements (using the toxicity characteristic leaching procedure (TCLP) and the Chinese GB/T 30810-2014 standard). It was found that the amount of sludge added (up to 0.7% of the feed composition) and use of different addition points for the sludge had no detrimental effect on the resulting cement quality. The retention ratios of heavy metals during sintering were related to their volatilities and the sludge addition points. The Cr concentration in leachate generated by the TCLP was far below the regulatory limit (5mg/L); however, when using the GB/T 30810-2014 procedure, the Cr concentration in the leachate exceeded the regulatory limit (200µg/L) when the sludge addition was greater than or equal to 0.5% and it was added at the kiln main burner position. Based on our laboratory study, tannery sludge might be added at the decomposing furnace addition point to reduce the Cr leachability of the resulting cement.

Addition of large amount of municipal sewage sludge as raw material in cement clinker production.

Two addition modes were used to explore the maximum addition of municipal sewage sludge as a raw material in cement clinker production. The clinker and cement product quality were determined by chemical analysis, cement quality testing, characterization of the clinker crystalline phases, and leaching tests. Municipal sewage sludge addition in the raw mix could be up to 30% based on the cement clinker moduli, and the cement quality met the P.O 42.5 cement standard (GB 175-2007). The amount of municipal sewage sludge added based on the direct addition mode should be less than 15% because of an insufficient early-term cement strength (third day). The leaching concentrations of heavy metals in all cements were below the threshold (GB 30760-2014) using the latest leaching procedure (GB 30810-2014). The municipal sewage sludge could be used with a high addition (30%) in the raw mix as a raw material in cement clinker production.

Cloned Guangxi Bama minipig (Sus scrofa) and its offspring have normal reproductive performance.

Xenotransplantation is a rapidly expanding field of research, and cloned miniature pigs are considered to be good model animals for its development. Although many animal species have been cloned, the success rate is very low, especially in the pig. To optimize the protocols for somatic cell nuclear transfer in the Guangxi Bama minipig, the relationship between cell cycle synchronization and nuclear histone acetylation levels were investigated. The results showed that the cells were efficiently synchronized by either serum starvation or contact inhibition. The level of nuclear histone acetylation in G0/G1 donor cells had similar variation trends in serum starvation and contact inhibition groups. When the synchronized donor cells were introduced into the enucleated oocytes, 8.8% (serum starvation group) or 9.7% (contact inhibition group) of the reconstructed embryos developed to blastocysts. After embryo transfer, one healthy male Guangxi Bama minipig was obtained. To evaluate the fertility of the cloned pig and its offspring, a series of mating experiments were done. Ninety-eight F1 generation crossbred piglets were born, of which 93 piglets survived. Also, the F1 pigs gave birth to 22 F2 generation piglets, of which 14 piglets survived. In conclusion, a Guangxi Bama minipig was successfully cloned from cultured newborn male gonad fibroblast cells, and the cloned minipig and its offspring had normal fertility.