Contrasting soil nitrogen dynamics under Zea mays and Miscanthus × giganteus: A story of complex interactions among site, establishment year, and nitrogen fertilization

Perennial cropping systems have been proposed as an alternative to conventional, annual cropping systems to improve water quality by increasing nitrogen (N) retention in the plant and soil. In this study, I used a staggered-start experimental design to compare a perennial cropping system, miscanthus (Miscanthus × giganteus Greef et Deu.) at two stand-ages (mature (3 years old), and juvenile (establishment year)) with an annual cropping system, continuous corn (Zea mays L.), across two N fertility treatments of 0 and 224 kg N ha-1. This experiment was duplicated at two locations in Iowa, USA with similar soil parent material, but different background soil fertility due to past fertilizer management. I measured pools and processes associated with N cycling dynamics, including inorganic soil N, net N mineralization, and N leaching. Also measured were soil health indicators, including soil microbial biomass carbon (C) and N, and potentially mineralizable C and N. Measurements were taken at different frequencies over two years. One of the most salient findings in this study was mature miscanthus’ ability to alter soil microclimate properties. Mature miscanthus increased soil temperature by 134% in the winter, and decreased it by 16% during the growing season, compared to continuous corn. Also, during the growing season juvenile miscanthus decreased soil moisture by 10% compared to continuous corn. Across both sites and all treatments net soil N mineralization showed large variability, but the juvenile miscanthus treatment, on average, had the greatest cumulative net N mineralization, and mature miscanthus the lowest. Across all sites and N rates, mature miscanthus reduced nitrate-N leaching by 64% compared to continuous corn. Juvenile miscanthus leached the same amount of nitrate-N as continuous corn. Since miscanthus changed soil microclimate properties and N dynamics compared to continuous corn, it was surprising to find very little effect of miscanthus on soil health indicators – microbial biomass or potentially mineralizable C and N. However, the soil aggregates (\u3c 2 mm diameter) under mature miscanthus could hold 11% more water than that under continuous corn. This study suggests that integrating miscanthus into the Midwestern Corn Belt would substantially reduce N leached through the soil profile, potentially preventing it from being lost to surface or groundwater. Miscanthus shows the potential to provide farm income while reducing the impact of agriculture on water quality, and some signs of improving soil health. More research is needed on the underlying mechanisms driving the differences in soil N dynamics between miscanthus and corn

Evidence-Based Elements of Child Welfare In-Home Services

In this article we discuss evidence-based elements of effective in-home child welfare services as a foundation for advancing the evidence base for family-centered child welfare practice. In 2009 the U.S. Children’s Bureau established the National Resource Center for In-Home Services to build the capacity of state and tribal child welfare agencies to ensure the safety and well-being of children and youth in their homes, prevent their initial placement or re-entry into out-of-home care, and to support families in their role as primary caregivers. Through a nationwide assessment of in-home services conducted over four years of research and technical assistance, we developed a set of core elements for in-home services. These core elements are supported by empirical research and are congruent with evidence-based practices and programs. We review each of the elements with its underlying research base. We also discuss five evidence-supported in-home services interventions that share many of the elements. We conclude with a discussion of how evidence-based elements can be implemented to strengthen family centered child welfare practice

A new mechanistic proposal for the aromatic cycle of the MTO process based on a computational investigation for H-SSZ-13

The paring mechanism of the aromatic cycle of the hydrocarbon pool is reinvestigated based on the heptamethylbenzenium cation adsorbed within H-SSZ-13 using quantum chemical calculations. Based on the outcome of our calculations we propose a modified mechanism to that presently existing in the literature, where ring contraction starts from hexamethylmethylenecyclohexadiene. After protonation and ring contraction, the unsaturated methylene side chain remains throughout this mechanism. This new mechanistic proposal avoids the formation of antiaromatic intermediates present in current proposals for the paring mechanism. The barriers for the modified paring mechanism are found to be significantly lower than those for the original proposal, being in the range from 130–150 kJ mol−1 at 400 °C and are thus accessible at typical MTO conditions

NH3_{3}-SCR over V-W/TiO2_{2} Investigated by Operando X-ray Absorption and Emission Spectroscopy

V–W/TiO$_{2}$-based catalysts, which are used for the removal of NO$_{x}$ from the exhaust of diesel engines and stationary sources via selective catalytic reduction with NH$_{3}$ (NH$_{3}$-SCR), were studied by operando X-ray absorption spectroscopy (XAS) and emerging photon-in/photon-out techniques. In order to minimize the influence of highly X-ray absorbing tungsten and the fluorescence of titanium, we used a high-energy-resolution fluorescence setup that is able to separate efficiently the V Kβ$_{1,3}$ emission lines and additionally allows to record valence-to-core (vtc) X-ray emission lines. High-energy resolution fluorescence-detected XAS (HERFD-XAS) and vtc X-ray emission spectroscopy (vtc-XES) proved to be the only way to perform an operando V K edge X-ray spectroscopic study on industrially relevant V–W/TiO$_{2}$ catalysts so far. The V–W/TiO$_{2}$ and V/TiO$_{2}$ samples synthesized by incipient wetness impregnation and grafting exhibited high activity toward NH$_{3}$-SCR. Raman spectroscopy showed that they mainly contained highly dispersed, isolated, and polymeric V-oxo species. HERFD-XAS and XES identified redox cycling of vanadium species between V$^{4+}$ and V$^{5+}$. With respect to most of the potential NH$_{3}$ adsorption complexes, density functional theory calculations further showed that vtc-XES is more limited than surface-sensitive techniques such as infrared spectroscopy; hence, a combination of X-ray techniques with IR or similar spectroscopies is required to unequivocally identify the mechanism of NH$_{3}$-SCR over vanadia-based catalysts

Supported Intermetallic PdZn Nanoparticles as Bifunctional Catalysts for the Direct Synthesis of Dimethyl Ether from CO-Rich Synthesis Gas

The single-step syngas-to-dimethyl ether (STD) process entails economic and technical advantages over the current industrial two-step process. Pd/ZnO-based catalysts have recently emerged as interesting alternatives to currently used Cu/ZnO/Al2O3 catalysts, but the nature of the active site(s), the reaction mechanism, and the role of Pd and ZnO in the solid catalyst are not well established. Now, Zn-stabilized Pd colloids with a size of 2 nm served as the key building blocks for the methanol active component in bifunctional Pd/ZnO-gamma-Al2O3 catalysts. The catalysts were characterized by combining high-pressure operando X-ray absorption spectroscopy and DFT calculations. The enhanced stability, longevity, and high dimethyl ether selectivity observed makes Pd/ZnO-gamma-Al2O3 an effective alternative system for the STD process compared to Cu/ZnO/gamma-Al2O3

School bullying from a sociocultural perspective

School bullying is an important concern. Whilst there is growing knowledge about the nature, extent and effects of school bullying, areas of complexity in research findings remain. In this paper we develop our thinking on school bullying using a sociocultural theoretical framework. We review existing literature around three main themes: 1) The conceptualisation and interpretation of bullying; 2) The relational aspects of bullying 3) Bullying as part of someone’s life trajectory. For each theme, empirical findings are discussed to highlight key issues, and arguments presented from relevant sociocultural theories to provide insight in each case. During the paper, we show how varying strands of research into bullying can be integrated, and how areas of complexity can be explained. Adopting a sociocultural view of school bullying presents implications for both research and practice. Bullying is contextual, and attention should be given to the situated relationships and multiple settings surrounding the behaviour