Characterization of Environmental Nano- and Macrocolloid Particles Extracted from Selected Soils and Biosolids

Environmental nanoparticles found in soil systems and biosolids may pose a considerable risk to groundwater quality as contaminant carriers. Little effort has been invested in the characterization of natural nanocolloids compared to corresponding macrocolloids. This study involved physicochemical, mineralogical, and morphological characterizations of nanocolloids and macrocolloids fractionated from three Kentucky soils and one biosolid. Particle size and morphology were investigated using scanning/transmission electron microscopy and dynamic light scattering. Mineralogical composition was determined by X-ray diffraction and thermogravimetric and Fourier-transform infrared spectroscopy analyses. Zeta potentials and cation exchange capacities assessed surface charge and chemical reactivity. The estimated average hydrodynamic diameter of nanoparticles was nearly twice the ideal 100 nm range, apparently due to irregular particle shapes and partial aggregation. Nanoparticles were also found attached to surfaces of macrocolloids, forming macro-nano aggregates and obscuring some of their physical and chemical characteristics. However, nanocolloids exhibited greater surface reactivity, likely due to their smaller size, poor crystallinity, and morphological shape distortions. In spite of some behavior modification due to nanoaggregation phenomena, nanocolloids appeared to be much more potent vectors of contaminant transport in subsurface environments than their macrosize fractions. Nevertheless, their heterogeneous nature brings to light important considerations in addressing pollution prevention and remediation challenges

Fragipan Horizon Fragmentation in Slaking Experiments with Amendment Materials and Ryegrass Root Tissue Extracts

Slaking experiments were conducted of fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H2O, CaCO3, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5–18.8 mm compared to the 44.2–47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. The poor efficiency of the poultry manure, ADB, and FBC treatments was attributed to their high ionic strength, while the high efficiency of the NaF, Na-hexa-metaphosphate, and rye grass root solutions to their high sodium soluble ratio (SSR). A slaking mechanism is proposed suggesting that aqueous solutions with high SSR penetrate faster into the fragipan capillaries and generate the critical swelling pressure and shearing stress required to rupture the fragipan into several fragments. Additional fragmentation occurs in a followup stage during which potential Si, Al, Fe, and Mn binding agents may be released into solution. Field experiments testing these findings are in progress

Alarm calling behavior of the thirteen-lined ground squirrel, Spermophilus tridecemlineatus

Alarm calling in a population of thirteenlined ground squirrels, Spermophilus tridecemlineatus , was studied over a three-year period. Data on ground squirrel reactions to human and canine approaches and to the approach or presence of avian predators were used to quantify alarm calling behavior.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46905/1/265_2004_Article_BF00299364.pd

A multiple timepoint pre-post evaluation of a ‘sexual respect’ dvd to improve competence in discussing sex with patients with disability

Sexual problems are common after chronic illnesses and disability, yet research indicates that this is a neglected area in healthcare services. Evaluation studies provide evidence of the effectiveness of education in enhancing professionals’ knowledge, skills, and comfort in addressing patients’ sexual concerns. However, there are limited evaluations aimed at improving ability to discuss sexuality when working with people with disabilities. The overall aim of this study was to evaluate a ‘Sexual Respect’ DVD as an intervention to improve competence in addressing ‘sexuality and disability’. A mixed methods design was used with both quantitative and qualitative components. Nursing students’ self-report ratings of knowledge, confidence, comfort and willingness (to discuss sexuality) levels were collected across four time points: baseline, pre-intervention, post-intervention, and follow-up. Data were analysed using one-way repeated measures ANOVAs with post hoc comparisons. Open-ended qualitative comments relating to the barriers and facilitators to discussing sexuality were analysed using content analysis and subsequent frequency analysis. Reported barriers included lack of knowledge about sex¬uality and disability issues, the patient’s level of disability, and waiting for the patient to raise sexuality issues first. Facilitators included education/training, written information, and if the patient raised it first. Overall, the DVD intervention had a significant and positive impact on nursing students’ self-reported knowledge, confidence, comfort and willingness levels. The findings are discussed in relation to the PLISSIT model, which emphasises the importance of a proactive approach to addressing sexuality issues

An overview of using small punch testing for mechanical characterization of MCrAlY bond coats

Considerable work has been carried out on overlay bond coats in the past several decades because of its excellent oxidation resistance and good adhesion between the top coat and superalloy substrate in the thermal barrier coating systems. Previous studies mainly focus on oxidation and diffusion behavior of these coatings. However, the mechanical behavior and the dominant fracture and deformation mechanisms of the overlay bond coats at different temperatures are still under investigation. Direct comparison between individual studies has not yet been achieved due to the fragmentary data on deposition processes, microstructure and, more apparently, the difficulty in accurately measuring the mechanical properties of thin coatings. One of the miniaturized specimen testing methods, small punch testing, appears to have the potential to provide such mechanical property measurements for thin coatings. The purpose of this paper is to give an overview of using small punch testing to evaluate material properties and to summarize the available mechanical properties that include the ductile-to-brittle transition and creep of MCrAlY bond coat alloys, in an attempt to understand the mechanical behavior of MCrAlY coatings over a broad temperature range

Colloid-mediated vertical phosphorus transport in a waste-amended soil

Vertical phosphorus (P) transport in relatively high clay content (≥10%) soils is often assumed to be a minor contributor to surface-water P enrichment, when compared with runoff-P losses. Studies have emphasized the importance of P sorbed by colloidal particles in runoff-P losses, but little is known about the role of soil colloids on the vertical P transport in manure-amended soils. The objectives of this study were: firstly, to determine the effect of water-dispersible soil colloids (WDC) isolated from a long-term (∼ 10 years) manure-amended soil on the forms and concentrations of leached-P from manured and unmanured intact soil columns; and secondly, to evaluate whether the potential for soluble and particulate-P transport was greater in manure-amended soil columns. Around 30% of the initially added WDC concentration was detected in the effluent of both manured and unmanured columns, although WDC particle breakthrough was earlier in the manured than that of the unmanured columns. Manure-amended soil columns exhibited higher P concentrations in all P forms (MRP, particulate) when compared to the unmanured. Breakthrough curves for inorganic-particulate P (IPP) and organic-particulate P (OPP) partially explained vertical P movement with WDC. In the manure-amended soils, dissolved inorganic P (MRP) concentrations were reduced in the presence of WDC relative to the untreated (no WDC added), but did not reduce MRP concentrations to levels observed with the unmanured columns. Iron-hydroxide-rich WDC particles exhibited similar breakthrough with particulate P and suggested an iron-phosphate association in the transported WDC fraction of the soil. Not only do naturally occurring WDC act as P carriers, but upon saturation of their P sorption sites are unable to reduce MRP “leaking” in long-term manured soils. Results illustrated the soluble and particulate P vertical transport through a waste-amended soil