Xiangzhi Li

Life cycle assessment of four municipal solid waste management scenarios in China.

A life cycle assessment was carried out to estimate the environmental impact of municipal solid waste. Four scenarios mostly used in China were compared to assess the influence of various technologies on environment: (1) landfill, (2) incineration, (3) composting plus landfill, and (4) composting plus incineration. In all scenarios, the technologies significantly contribute to global warming and increase the adverse impact of non-carcinogens on the environment. The technologies played only a small role in the impact of carcinogens, respiratory inorganics, terrestrial ecotoxicity, and non-renewable energy. Similarly, the influence of the technologies on the way other elements affect the environment was ignorable. Specifically, the direct emissions from the operation processes involved played an important role in most scenarios except for incineration, while potential impact generated from transport, infrastructure and energy consumption were quite small. In addition, in the global warming category, highest potential impact was observed in landfill because of the direct methane gas emissions. Electricity recovery from methane gas was the key factor for reducing the potential impact of global warming. Therefore, increasing the use of methane gas to recover electricity is highly recommended to reduce the adverse impact of landfills on the environment.

Polycomblike 2 facilitates the recruitment of PRC2 Polycomb group complexes to the inactive X chromosome and to target loci in embryonic stem cells

Polycomb group (PcG) proteins play an important role in the control of developmental gene expression in higher organisms. In mammalian systems, PcG proteins participate in the control of pluripotency, cell fate, cell cycle regulation, X chromosome inactivation and parental imprinting. In this study we have analysed the function of the mouse PcG protein polycomblike 2 (Pcl2), one of three homologues of the Drosophila Polycomblike (Pcl) protein. We show that Pcl2 is expressed at high levels during early embryogenesis and in embryonic stem (ES) cells. At the biochemical level, Pcl2 interacts with core components of the histone H3K27 methyltransferase complex Polycomb repressive complex 2 (PRC2), to form a distinct substoichiometric biochemical complex, Pcl2-PRC2. Functional analysis using RNAi knockdown demonstrates that Pcl2-PRC2 facilitates both PRC2 recruitment to the inactive X chromosome in differentiating XX ES cells and PRC2 recruitment to target genes in undifferentiated ES cells. The role of Pcl2 in PRC2 targeting in ES cells is critically dependent on a conserved PHD finger domain, suggesting that Pcl2 might function through the recognition of a specific chromatin configuration.

Mammalian Polycomb-Like Pcl2/Mtf2 Is a Novel Regulatory Component of PRC2 That Can Differentially Modulate Polycomb Activity both at the Hox Gene Cluster and at Cdkn2a Genes.

ABSTRACT The Polycomb group of proteins forms at least two distinct complexes designated the Polycomb repressive complex-1 (PRC1) and PRC2. These complexes cooperate to mediate transcriptional repression of their target genes, including the Hox gene cluster and the Cdkn2a genes. Mammalian Polycomb-like gene Pcl2/Mtf2 is expressed as four different isoforms, and the longest one contains a Tudor domain and two plant homeodomain (PHD) fingers. Pcl2 forms a complex with PRC2 and binds to Hox genes in a PRC2-dependent manner. We show that Pcl2 is a functional component of PRC2 and is required for PRC2-mediated Hox repression. Pcl2, however, exhibits a profound synergistic effect on PRC1-mediated Hox repression, which is not accompanied by major alterations in the local trimethylation of histone H3 at lysine 27 (H3K27me3) or PRC1 deposition. Pcl2 therefore functions in collaboration with both PRC2 and PRC1 to repress Hox gene expression during axial development. Paradoxically, in embryonic fibroblasts, Pcl2 is shown to activate the expression of Cdkn2a and promote cellular senescence, presumably by suppressing the catalytic activity of PRC2 locally. Taken together, we show that Pcl2 differentially regulates Polycomb-mediated repression of Hox and Cdkn2a genes. We therefore propose a novel role for Pcl2 to modify functional engagement of PRC2 and PRC1, which could be modulated by sensing cellular circumstances.

Environmental assessment of sewage sludge as secondary raw material in cement production--a case study in China.

A life cycle assessment was carried out to estimate the environmental impact of sewage sludge as secondary raw material in cement production. To confirm and add credibility to the study, uncertainty analysis was conducted. Results showed the impact generated from respiratory inorganics, terrestrial ecotoxicity, global warming, and non-renewable energy categories had an important contribution to overall environmental impact, due to energy, clinker, and limestone production stages. Also, uncertainty analysis results showed the technology of sewage sludge as secondary raw material in cement production had little or no effect on changing the overall environmental potential impact generated from general cement production. Accordingly, using the technology of sewage sludge as secondary raw material in cement production is a good choice for reducing the pressure on the environment from dramatically increased sludge disposal. In addition, increasing electricity recovery rate, choosing natural gas fired electricity generation technology, and optimizing the raw material consumption in clinker production are highly recommended to reduce the adverse effects on the environment.

Life cycle assessment of electronic waste treatment

Life cycle assessment was conducted to estimate the environmental impact of electronic waste (e-waste) treatment. E-waste recycling with an end-life disposal scenario is environmentally beneficial because of the low environmental burden generated from human toxicity, terrestrial ecotoxicity, freshwater ecotoxicity, and marine ecotoxicity categories. Landfill and incineration technologies have a lower and higher environmental burden than the e-waste recycling with an end-life disposal scenario, respectively. The key factors in reducing the overall environmental impact of e-waste recycling are optimizing energy consumption efficiency, reducing wastewater and solid waste effluent, increasing proper e-waste treatment amount, avoiding e-waste disposal to landfill and incineration sites, and clearly defining the duties of all stakeholders (e.g., manufacturers, retailers, recycling companies, and consumers).

Environmental assessment of recycled printing and writing paper: A case study in China

A life cycle assessment was conducted using IMPACT2002+ to estimate the environmental impact of producing printing and writing paper, which is entirely made with wastepaper. To confirm and add credibility to the study, uncertainty analysis was conducted using Taylor series expansion. Printing and writing paper produced from wood pulp was assessed for comparison. Compared with the wood pulp contained scenario, printing and writing paper made from wastepaper represented environmental benefit on non-carcinogens, respiratory inorganics, global warming, and non-renewable energy categories. In both scenarios, the technologies significantly contribute to the potential impacts of non-carcinogens, respiratory inorganics, terrestrial ecotoxicity, global warming, and non-renewable energy. The influence of the technologies on the way other categories affect the environment was negligible. Improved efficiency in electricity consumption, decreased transport distance from raw material buyers to suppliers, and change in the end-life treatment of solid waste from landfill to incineration are the key factors in reducing the overall environmental impact.

Effects of electron donors on the microbial reductive dechlorination of hexachlorocyclohexane and on the environment.

The reductive biotransformation of α-, β-, γ-, and δ-hexachlorocyclohexane isomers was investigated using five alternative electron donors (i.e., glucose plus methanol, glucose only, methanol only, acetate, and ethanol) in a batch assay of an HCH-dechlorinating anaerobic culture. In addition, a life cycle assessment was conducted using the IMPACT2002+ method to evaluate the environmental effects of HCH bioremediation with the aforementioned electron donors. Results showed that the electron donors methanol plus glucose, ethanol, glucose, and methanol can significantly enhance the biotransformation of each HCH isomer. However, the amended electron donors and the byproduct of the anoxic/anaerobic systems may negatively affect the environment (e.g., respiratory inorganic, land occupation, global warming, and non-renewable energy categories). These effects are attributed to the electron donor production processes. To avoid secondary pollutants, a linear relationship between the upper bound electron donor applications and HCH concentration was observed from an environmental perspective. Results indicated that the methanol scenario was the most suitable option for the current research.

Life cycle environmental assessment of industrial hazardous waste incineration and landfilling in China

PurposeThe improper handling of industrial hazardous waste (IHW), which comprises large amounts of toxic chemicals, heavy metals, or irradiation substances, is a considerable threat to human health and the environment. This study aims to quantify the life cycle environmental impacts of IHW landfilling and incineration in China, to identify its key factors, to improve its potential effects, and to establish a hazardous waste disposal inventory.MethodsLife cycle assessment was conducted using the ReCiPe model to estimate the environmental impact of IHW landfilling and incineration. The characterization factors for the human toxicity and freshwater ecotoxicity categories shown in the ReCiPe were updated based on the geographies, population, food intake, and environmental conditions in China.Results and discussionThe overall environmental burden was mainly attributed to the carcinogen category. The national carcinogen burden in 2014 at 37.8 CTUh was dominated by diesel consumption, cement and sodium hydroxide production, direct emission, transportation, and electricity generation stages caused by direct mercury and arsenic emissions, as well as indirect chromium emission. Although the atmospheric mercury emission directly caused by IHW incineration was comparative with the emission levels of developed countries, the annual direct mercury emission accounted for approximately 0.1% of the national mercury emission.ConclusionsThe key factors contributing to the reduction of the national environmental burden include the increasing diesel and electricity consumption efficiency, the reduction of cement and sodium hydroxide use, the development of air pollutant controlling systems, the reduction of transport distance between IHW disposers to suppliers, and the improvement of IHW recycling and reuse technologies.

Histone Acetyltransferase Mof Affects the Progression of DSS-Induced Colitis.

Background/Aims: Histone acetylation has been demonstrated to be associated with inflammation response. Histone acetyltransferase (HAT) Mof, specifically acetylating lysine 16 of histone H4 (H4K16), has been reported to regulate T cell differentiation. In addition, it has been suggested that acetylation of H4K16 is associated with the inflammatory response. We evaluated the role and potential mechanism of Mof in the development of experimental colitis. Methods: We used Mof conditional knockout mice to study the role of Mof in dextran sulfate sodium (DSS)-induced colitis and detected the differential expression of genes due to Mof deficiency involved in the inflammatory response, particularly the Th17 signaling pathway, by western blotting, quantitative PCR and RNA sequencing (RNA-seq). Results: A significant elevation of Mof was observed in colonic tissues of mice with DSS-induced colitis. Mof deficiency alleviated the severity of DSS- induced colitis in mice. We found that Th17 signaling pathway associated genes, including Il17a, Il22, RORγt, RORα, Stat3, TGF-β 1, and Il6, were downregulated in colon tissues with Mof deficiency. RNA-seq data analysis suggested that 68 genes were related to inflammatory response processing and 47 genes were downregulated in Mof defective colon tissues. Conclusion: Our study demonstrated that HAT Mof is involved in the development of colitis, and the lack of Mof ameliorates DSS-induced colitis in mice.

The histone acetyltranseferase KAT8 regulates cell differentiation by suppression of MN1 in AML

K(lysine) acetyltransferase 8 (KAT8, also known as MOF or MYST1) was originally identified as an essential component of the dosage compensation in Drosophila, causing a twofold increase in the expression of X-linked genes in male flies (Rea et al, 2007). The corresponding acetylation of histone H4 at lysine 16 (H4K16ac) is closely related to KAT8 expression level. The global reduction of H4K16ac and depletion of KAT8 in mammal cells can result in abnormal gene transcription, especially causing abnormal expression of certain tumours. Despite all the improvements in the study and treatment of acute myeloid leukaemia (AML), there is little information about KAT8 expression in leukaemic cells from AML patients. Bone marrow (BM) samples were obtained from 50 patients with AML upon diagnosis (see Table SI for Patient characteristics). U937, HL-60 and K562 cell lines were obtained from the American Type Culture Collection (Manassas, VA, USA). U937 cells were treated with 100 nM