Reductive immobilization of radioactive pertechnetate (99TcO4−) in simulated groundwater was studied by prepared carboxymethyl cellulose (CMC) and starch stabilized zero valent iron nanoparticles (nZVI), and long-term remobilization of reduced Tc was also evaluated under anoxic and oxic conditions. The stabilized nZVI can effectively reduce soluble 99Tc(VII) to insoluble 99Tc(IV), and they can be easily delivered into a contaminated groundwater zone and facilitate in situ remediation. In this study, CMC-stabilized nZVI showed higher reactivity than that using starch as the stabilizer. Batch experiments indicated that more than 99% of 99Tc(VII) (C0=12mg/mL) was reduced and removed from groundwater by CMC-stabilized nZVI with a CMC content of 0.2% (w/w) at a broad pH of 5–8. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses further confirmed that 99Tc(VII)O4− transformed into 99Tc(IV)O2 (s). The presence of bicarbonate exhibited insignificant effect on Tc immobilization, while humic acid (HA) inhibited reaction mainly due to retardation on electron transfer and formation of Tc(IV)-HA complexes. More interesting, the immobilized Tc(IV) remained insoluble even after 120 d under anoxic condition, while only ∼21% was remobilized when exposed to air. Therefore, bio-macromolecules stabilized nZVI nanoparticles could be a viable alternative for in situ remediation of radioactive contamination in groundwater.
Abstract Aim Dryland ecosystems are exceedingly sensitive to climate change. Desertification induced by both climate changes and human activities seriously threatens dryland vegetation. However, the impact of climate change on distribution of dryland plant species has not been well documented. Here, we studied the potential distribution of four representative dryland plant species (Haloxylon ammodendron, Anabasis aphylla, Calligonum mongolicum, and Populus euphratica) under current and future climate scenarios in a temperate desert region, aiming to improve our understanding of the responses of dryland plant species to climate change and provide guidance for dryland conservation and afforestation. Location Junggar Basin, a large desert region in northwestern China. Methods Occurrence data of the studied species were collected from an extensive field investigation of 2,516 sampling sites in the Junggar Basin. Ensemble species distribution models using 10 algorithms were developed and used to predict the potential distribution of each studied species under current and future climate scenarios. Result Haloxylon ammodendron and A. aphylla were likely to lose most of their current suitable habitats under future climate scenarios, while C. mongolicum and P. euphratica were likely to expand their ranges or remain relatively stationary. Variable importance evaluation showed that the most important climate variables influencing species distribution differed across the studied species. These results may be explained by the different ecophysiological characteristics and adaptation strategies to the environment of the four studied species. Main conclusions We explored the responses of the representative dryland plant species to climate change in the Junggar Basin in northwestern China. The different changes in suitability of different species imply that policymakers may need to reconsider the selection and combination of the afforestation species used in this area. This study can provide valuable reference for the management and conservation of dryland ecosystems under future climate change scenarios.
Lab-on-a-chip has been used widely in rapid, high-throughput and low-consumption analysis of samples in biochemistry. The ion concentration polarization (ICP) produced by ion-selective transport of nanochannels provides a novel solution for problems in ultra-low concentration sample detection, systems biology and desalination. This paper reviews the applications of ion transport based on the principle of ICP in micro-nanofluidic systems. First, the fundamental governing equations of ICP are described. Then, the applications of nano-electrokinetic ion enrichment and ion current rectification (ICR) are introduced. Nano-electrokinetic ion enrichment is used mainly in the fields of molecular enrichment, ultra-low concentration sample detection and seawater desalination. ICR is applied mainly to the sensitive detection of analytical substances such as proteins, nucleic acids and small molecules. The application of ion transport based on ICP principle is summarized and the possible directions worthy of further research are proposed. (c) 2019 Society of Chemical Industry
Geoffrey Robinson’s The Killing Season is one of the most-awaited books by the Southeast Asian studies community in 2018. The 456-page monograph explores in great detail the anti-communist massacres of Indonesia in 1965-66 and the long-term repercussions in the following decades. As one of the worst human atrocities in the 20th century, the mass killing led to the death of some half a million real and alleged communist members and sympathizers. After more than 50 years, however, reflections on this tragic event are far from sufficient. Although academic work in recent years spurred growing discussions within small circles, the mass violence has not received adequate attention from the international audience. Worse still, a troubling silence permeates Indonesia even today, as many of those who committed the atrocities have stayed in power. While victims struggled to find viable ways to pursue justice, numerous murderers managed to get away with impunity.
An accurate determination of the minimum miscibility pressure (MMP) is required for the miscible gas injection project in oilfield. The experimental methods are usually considered to be an available and appropriate way to determine the MMPs, while so far few study has been found to systematically review and evaluate the experimental MMP determination methods. In this study, for the first time, ten existing experimental methods and their three important technical aspects, including the experimental design, operating procedure, and MMP criterion, are critically reviewed for determining the MMPs. Then, the three technical parts for each experimental method are specifically evaluated and scored from thirteen factors. On the basis of the evaluation results, a novel and effective screening table, which is coupled with the weight analysis, is initially developed to assist the selection of the most appropriate MMP experiment for different specific conditions. From the previously published studies, the conventional slim-tube tests, rising-bubble apparatus (RBA), and vanishing interfacial tension (VIT) technique are still the three most widely-used experimental methods for the MMP determinations. Results from this study indicate that the slim-tube and coreflood tests are the best experimental methods for the MMP determinations, which are followed by the RBA, VIT technique, and microfluidic test. Future work with respect to the experimental design, operating procedure, and MMP criteria are expected to improve the existing experimental methods and possibly initiate a completely standardized experimental method for the MMP determinations.
As recent trends in comparing the Han and Roman empires from primarily the point of view of literary evidence has brought forth new frameworks and opportunities of research, one asks how these developments could contribute to the comparison of the two empires' governance behaviors. The paper first surveys current literature published in the past decade and identify common themes in the scholarship on the Han and the Roman metallurgical advances and aspects of their iron industries. Of particular focus is the gradual awareness in the importance of iron semi-products in the Han and the Roman domains. In the second and third section, literary sources from the Qin-Han and the Roman domains are reviewed in order to identify general trends that can be juxtaposed for closer discussion. Particular emphasis is placed on the relationship between the private iron operators with generational legacies in the iron industries even be fore the formation of the Qin-Han and the Roman states, and how the state administrators engage with and adapt to the sophisticated and complex traditions of the Qin-Han and Roman iron industries. The fourth section provides a comparative discussion on issues concerning the states' juridical or statutory approaches to regulating iron mining and smelting operations, and observations on the intersect between semi-products, local ironworks andsmithies, and the needs of agricultural producers.
Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities. This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity. Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.
Nitrous oxide (N2O) emission from wastewater treatment plants (WWTPs) has become a focus of attention due to its significant greenhouse effect. In this study, the role of sludge retention time (SRT) in mitigation of N2O emission from a pilot-scale oxidation ditch was systematically investigated. The activated sludge system that operated at SRT of 25 days demonstrated significantly lower N2O emission factor, higher resistance to ammonia overload and aeration failure shock than those obtained at SRT of 15 days no matter which hydraulic retention time (HRT) was adopted. Batch experiments revealed that nitrifier denitrification (ND) was the primary mechanism of N2O generation. However, more microbes affiliated with Nitrospira genera were harbored in the system at SRT 25 d, which could effectively avoid nitrite accumulation, a key factor promoting N2O generation by ND. PICRUSt results further suggested the system at SRT 25 d possessed higher genetic potential for N2O reduction reflected by the more abundant nitrous-oxide reductase.