Morphological and mineral features of nZVI induced precipitation on quartz particles

Nano Zero-Valent Iron (nZVI) is a versatile nanomaterial that can not only efficiently remove contaminants in soil, but also improve the soil’s geotechnical strength by changing their physicochemical properties. Inert solid mineral particles are the most common ingredients in soils, they present universal surface modification after the nZVI treatment. This study presents an investigation on the morphological and mineral features of nZVI induced iron mineral precipitations on quartz particles. Lead was employed as the artificial contaminant, while quartz was used to mimic the inert solid mineral particles in soil. Scanning Electron Microscope (SEM), Digital Image Analysis (DIA), Transmission Electron Microscopy (TEM), laser particle size analyzer, X-ray diffraction (XRD) and Raman spectrum were carried out for the characterization. The results indicate that iron minerals precipitated heterogeneously on the surface of quartz particles with plush-like and flake-like structure. They are made of deuterogenic plumbiferous minerals and ferriferous minerals. XRD analysis demonstrated that these minerals are amorphous. The curly flake-like mineral clusters were scatteredly distributed on the surface of quartz along with the of corroded nZVI aggregation. The thickness of the curly flake-like precipitation varied from 20 nm to 60 nm, and 20 nm to 35 nm for the plush-like precipitation. The generation of these iron mineral precipitations led to a slight increase in the average particle size and a decrease in the surface area of the soil. However, no clear difference in the shape and roughness of quartz was found after the nZVI treatment. This study is provided to improve the understanding of mass transfer from nZVI to inert solid particles in soil and its effect in soil improvement

Microstructure and morphological characterization of lead-contaminated clay with nanoscale zero-valent iron (nZVI) treatment

The increasing use of nanoscale zero-valent iron (nZVI) for soil and groundwater remediation has raised concerns about its potential effect on soil properties. Numerous laboratory and field studies have demonstrated its excellent capability to immobilize contaminants and enhance contaminated soil. However, a few studies have shed light on the changes in the microstructure and morphology of the soil due to nZVI treatment. This study explores the variation in particle morphology and microstructure in nZVI-treated soil. A series of microscale experiments, including field emission scanning electron microscopy (FESEM), particle size analysis, mercury injection porosimetry (MIP), optical microscopic analysis, and particle shape tests, were conducted on nZVI-treated samples. The dosages of nZVI used were 0%, 0.2%, 1%, 5%, and 10% of the contaminated soil. Morphological characterization suggested that the addition of nZVI resulted in the occurrence of larger-sized particles, on-particle branched structures, finer pore size distribution, aggregation, and a flocculent network in the soil structure. The aggregated and bonded soil particles via nZVI could be one of the mechanisms for its variation in geotechnical characteristics. The findings of this study may improve our understanding of soil improvement using nZVI treatment

Simultaneous stabilization of Pb and improvement of soil strength using nZVI

This study demonstrates the feasibility of nanoscale Zero-Valent Iron (nZVI) for simultaneous stabilization of Pb and improvement of soil strength via batch experiments. The soil samples were prepared using slurry and pre-consolidation method at nZVI doses of 0.2%, 1%, 5%, and 10% (by dry weight). The physicochemical and geotechnical properties of Pb-contaminated soil treated by nZVI were analyzed. The results indicate that the contamination of Pb(II) resulted in a notable reduction in the undrained shear strength of soil from 16.85 kPa to 7.25 kPa. As expected, the Pb in exchangeable and carbonate-bound fractions decreased significantly with the increasing doses of nZVI. Meanwhile, the undrained shear strength of Pb-contaminated soil enhanced substantially as the increase of nZVI, from 25.83 kPa (0.2% nZVI treatment) to 69.33 kPa (10% nZVI treatment). An abundance of bubbles, generated from the oxidation of nZVI, was recorded. The mechanisms for simultaneous stabilization of Pb and soil improvement primarily include: 1) the precipitation and transformation of Pb-/Fe-hydrated oxides on the soil particles and their induced bounding effects; 2) the increased drainage capability of soil as the occupation of nZVI aggregates and bubbles in the macropores space and 3) the lower soil density derived from the increase in microbubbles retained in the soil. This study is provided to facilitate the application of nZVI in the redevelopment of contaminated soil

Cortical brain abnormalities in 4474 individuals with schizophrenia and 5098 control subjects via the enhancing neuro Imaging genetics through meta analysis (ENIGMA) Consortium

BACKGROUND: The profile of cortical neuroanatomical abnormalities in schizophrenia is not fully understood, despite hundreds of published structural brain imaging studies. This study presents the first meta-analysis of cortical thickness and surface area abnormalities in schizophrenia conducted by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Schizophrenia Working Group. METHODS: The study included data from 4474 individuals with schizophrenia (mean age, 32.3 years; range, 11-78 years; 66% male) and 5098 healthy volunteers (mean age, 32.8 years; range, 10-87 years; 53% male) assessed with standardized methods at 39 centers worldwide. RESULTS: Compared with healthy volunteers, individuals with schizophrenia have widespread thinner cortex (left/right hemisphere: Cohen's d = -0.530/-0.516) and smaller surface area (left/right hemisphere: Cohen's d = -0.251/-0.254), with the largest effect sizes for both in frontal and temporal lobe regions. Regional group differences in cortical thickness remained significant when statistically controlling for global cortical thickness, suggesting regional specificity. In contrast, effects for cortical surface area appear global. Case-control, negative, cortical thickness effect sizes were two to three times larger in individuals receiving antipsychotic medication relative to unmedicated individuals. Negative correlations between age and bilateral temporal pole thickness were stronger in individuals with schizophrenia than in healthy volunteers. Regional cortical thickness showed significant negative correlations with normalized medication dose, symptom severity, and duration of illness and positive correlations with age at onset. CONCLUSIONS: The findings indicate that the ENIGMA meta-analysis approach can achieve robust findings in clinical neuroscience studies; also, medication effects should be taken into account in future genetic association studies of cortical thickness in schizophrenia

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Hu Shih and popular education in the May Fourth Period

Includes bibliographical references (pages [63]-66)Hu Shih (1891-1962) was one of the most influential figures in modern Chinese intellectual history. The highlight of his life was shown in the May Fourth Period (1915-1921), an era that needed and created thinkers. This thesis describes the historical context of Chinese intellectuals' learning from the West, Hu's early education at home, his American experience, and his activities after returning to China. An attempt is made to draw some lessons from Hu's history by analyzing the impact of education on his intellectual development and his role in the popular education of the May Fourth Period so as to emphasize the importance of critical assimilation and application of knowledge.M.S. Ed. (Master of Education