Birds of a feather eat plastic together: high levels of plastic ingestion in Great Shearwater adults and juveniles across their annual migratory cycle.

Limited work to date has examined plastic ingestion in highly migratory seabirds like Great Shearwaters (Ardenna gravis) across the their entire migratory range, although this species is prone to ingest plastic as a wide-ranging procellariiform. We examined 217 Great Shearwaters obtained from 2008-2019 at multiple locations spanning their yearly migration cycle across the Northwest and South Atlantic to assess accumulation of ingested plastic as well as trends over time and between locations. A total of 2,328 plastic fragments were documented in the ventriculus portion of the gastrointestinal tract, with an average of 9 plastic fragments per bird. The mass, count, and frequency of plastic occurrence (FO) varied by location, with higher plastic burdens but lower FO in South Atlantic individuals from the breeding colonies. No fragments of the same size or morphology were found in the primary forage fish prey, the sand lance, (Ammodytes spp., n = 202) that supports Great Shearwaters in Massachusetts Bay, USA, suggesting the birds directly ingest the bulk of their plastic loads rather than accumulating via trophic transfer. Fourier-transform infrared spectroscopy indicated that low- and high-density polyethylene were the most common polymers ingested, within all years and locations. Individuals from the South Atlantic contained a higher proportion of larger plastic items and fragments compared to juveniles and non-breeding adults from the NW Atlantic, possibly due to increased use of remote, pelagic areas subject to reduced inputs of smaller, more diverse, and potentially less buoyant plastics found adjacent to coastal margins. Different signatures of polymer type, size, and category between similar life stages at different locations suggests rapid turnover of ingested plastics commensurate with migratory stage and location, though more empirical evidence is needed to ground-truth this hypothesis. This work is the first to comprehensively measure the accumulation of ingested plastics by Great Shearwaters over the last decade and across multiple locations spanning their yearly trans-equatorial migration cycle, and underscores their utility as sentinels of plastic pollution in Atlantic ecosystems.

Oral absorption of PEG-coated versus uncoated gold nanospheres: does agglomeration matter?

BACKGROUND: Particle size is thought to be a critical factor affecting the bioavailability of nanoparticles following oral exposure. Nearly all studies of nanoparticle bioavailability focus on characterization of the primary particle size of the material as supplied or as dosed, and not on agglomeration behavior within the gastrointestinal tract, which is presumably most relevant for absorption. METHODS: In the study reported here, snapshots of agglomeration behavior of gold nanospheres were evaluated in vivo throughout the gastrointestinal tract using transmission electron microscopy. Agglomeration state within the gastrointestinal tract was then used to help explain differences in gastrointestinal particle absorption, as indicated by tissue levels of gold detected using inductively coupled plasma mass spectrometry. Mice were dosed (10 mg/kg) with either 23 nm PEG-coated or uncoated gold nanospheres. RESULTS: Transmission electron microscopy demonstrates that PEG-coated gold nanoparticles can be observed as primary, un-agglomerated particles throughout the gastrointestinal tract and feces of dosed animals. In contrast, uncoated gold nanoparticles were observed to form agglomerates of several hundred nanometers in all tissues and feces. Inductively coupled plasma mass spectrometry shows significantly higher levels of gold in tissues from animals dosed with PEG-coated versus uncoated 23 nm gold nanoparticles. Retention of particles after a single oral gavage was also very high, with all tissues of animals dosed with PEG-coated particles having detectable levels of gold at 30 days following exposure. CONCLUSIONS: Qualitative observation of these particles in vivo shows that dispersed PEG-coated particles are able to reach the absorptive tissues of the intestine while agglomerated uncoated particles are sequestered in the lumen of these tissues. However, the large differences observed for in vivo agglomeration behavior were not reflected in oral absorption, as indicated by gold tissue levels. Additional factors, such as surface chemistry, may have played a more important role than in vivo particle size and should be investigated further.

Differential interferences with clinical chemistry assays by gold nanorods, and gold and silica nanospheres.

Nanomaterials are known to cause interference with several standard toxicological assays. As part of an in vivo study of PEG-coated gold nanorods in mice, nanorods were added to reference serum, and results for standard clinical chemistry parameters were compared with serum analyzed without nanorods. PEG-coated gold nanorods produced several concentration-dependent interferences. Comparisons were then made with PEG-coated gold and silica nanospheres. Interferences were observed for both materials that differed from gold nanorods. Removal of the particles from serum by centrifugation prior to analysis resolved most, but not all of the interferences. Additional clinical chemistry analyzers were used to further investigate trends in assay interference. We conclude that PEG-coated gold and silica nanoparticles can interfere with standard clinical chemistry tests in ways that vary depending upon material, shape, and specific assay methodology employed. Assay interferences by nanomaterials cannot always be predicted, underscoring the need to verify that nanomaterials under study do not interfere with methods used to evaluate potential biological effects.

The Image Gently pediatric digital radiography safety checklist: tools for improving pediatric radiography.

Transition from film-screen to digital radiography requires changes in radiographic technique and workflow processes to ensure that the minimum radiation exposure is used while maintaining diagnostic image quality. Checklists have been demonstrated to be useful tools for decreasing errors and improving safety in several areas, including commercial aviation and surgical procedures. The Image Gently campaign, through a competitive grant from the FDA, developed a checklist for technologists to use during the performance of digital radiography in pediatric patients. The checklist outlines the critical steps in digital radiography workflow, with an emphasis on steps that affect radiation exposure and image quality. The checklist and its accompanying implementation manual and practice quality improvement project are open source and downloadable at www.imagegently.org. The authors describe the process of developing and testing the checklist and offer suggestions for using the checklist to minimize radiation exposure to children during radiography.

Characterization of nanomaterials for toxicological studies.

The scientific community, regulatory agencies, environmentalists, and most industry representatives all agree that more effort is required to ensure the responsible and safe development of new nanotechnologies. Characterizing nanomaterials is a key aspect in this effort. There is no universally agreed upon minimum set of characteristics although certain common properties are included in most recommendations. Therefore, characterization becomes more like a puzzle put together with various measurements rather than a single straightforward analytical measurement. In this chapter, we emphasize and illustrate the important elements of nanoparticle characterization with a systematic approach to physicochemical characterization. We start with an overview describing the properties that are most significant to toxicological testing along with suggested methods for characterizing an as-received nanomaterial and then specifically address the measurement of size, surface properties, and imaging.

Influence of Suwannee River humic acid on particle properties and toxicity of silver nanoparticles.

Adsorption of natural organic matter (NOM) on nanoparticles can have dramatic impacts on particle dispersion resulting in altered fate and transport as well as bioavailability and toxicity. In this study, the adsorption of Suwannee River humic acid (SRHA) on silver nanoparticles (nano-Ag) was determined and showed a Langmuir adsorption at pH 7 with an adsorption maximum of 28.6 mg g(-1) nano-Ag. It was also revealed that addition of <10 mg L(-1) total organic carbon (TOC) increased the total Ag content suspended in the aquatic system, likely due to increased dispersion. Total silver content decreased with concentrations of NOM greater than 10mg TOCL(-1) indicating an increase in nanoparticle agglomeration and settling above this concentration. However, SRHA did not have any significant effect on the equilibrium concentration of ionic Ag dissolved in solution. Exposure of Daphnia to nano-Ag particles (50 µg L(-1) and pH 7) produced a linear decrease in toxicity with increasing NOM. These results clearly indicate the importance of water chemistry on the fate and toxicity of nanoparticulates.

Investigation of acute nanoparticulate aluminum toxicity in zebrafish.

In freshwater fish, aluminum is a well-recognized gill toxicant, although responses are influenced by pH. Aluminum nanomaterials are being used in diverse applications that are likely to lead to environmental release and exposure. However, it is unclear if the effects of nanoparticulate aluminum are similar to those of other forms of aluminum or require special consideration. To examine the acute toxicological effects of exposure to aluminum nanoparticle (Al-NP)s, adult female zebrafish were exposed to either Al-NPs or aluminum chloride for up to 48 hours in moderately hard fresh water. Al-NPs introduced into test water rapidly aggregated and up to 80% sedimented from the water column during exposures. No mortality was caused by concentrations of Al-NP up to 12.5 mg/L. After exposure, tissue concentrations of aluminum, effects on gill morphology, Na+, K+ -ATPase (NKA) activity, and global gene expression patterns were examined. Exposure to both aluminum chloride and nanoparticulate aluminum resulted in a concentration dependent decrease in sodium potassium ATPase activity, although Al-NP exposure did not alter gill morphology as measured by filament widths. Decreased ATPase activity coincided with decreases in filamental NKA staining and mucous cell counts. Analysis of gill transcriptional responses demonstrated that exposure to 5 mg/L Al-NP only resulted in significant changes in expression of two genes, whereas aluminum chloride exposure significantly affected the expression of 105 genes. Taken together, these results indicate that nanoparticulate aluminum has little acute toxicity for zebrafish in moderately hard freshwater.

Amorphous silica coatings on magnetic nanoparticles enhance stability and reduce toxicity to in vitro BEAS-2B cells.

BACKGROUND: Nanoparticles are being rapidly assimilated into numerous research fields and consumer products. A concurrent increase in human exposure to such materials is expected. Magnetic nanoparticles (MNPs) possess unique and beneficial features, increasing their functionality and integrative potential. However, MNP toxicity characterization is limited, especially in regards to the human respiratory system. This study aimed to assess the in vitro effects of airborne MNPs on BEAS-2B cells. Uncoated iron oxide was compared with two amorphous silica-coated MNPs, hypothesizing the coatings reduced toxicity and increased particle stability. METHOD: BEAS-2B cells were cultured at an air-liquid interface and exposed to airborne MNPs using a fabricated exposure device. Indices of cytotoxicity, inflammatory response, oxidative stress, and iron homeostasis were monitored postexposure via cell viability assays and qRT-PCR. Concentrations of soluble iron-associated with different MNPs were also examined before and after contact with several aqueous organic and inorganic acids. RESULTS: The silica-coated MNPs had reduced soluble iron concentrations. This result indicates that the silica coating provides a barrier to and prevents the mobilization of soluble iron from the particle to the cell, thereby reducing the risk of oxidative stress or alterations of iron homeostasis. Cells exposed to MagSilica50 and MagSilica50-85® showed little to no indications of cytotoxicity or induction of inflammatory response/oxidative stress at the examined delivery concentrations. CONCLUSION: MNPs coated with amorphous silica are protected from acidic erosion. Correspondingly, the particle stability translates into reduced cytotoxicity and cellular influence on human airway epithelial cells.

Nanoparticle characterization for cancer nanotechnology and other biological applications.

Nanotechnology is actively being used to develop promising diagnostics and therapeutics tools for the treatment of cancer and many other diseases. The unique properties of nanomaterials offer an exciting frontier of possibilities for biomedical researchers and scientists. Because existing knowledge of macroscopic materials does not always allow for adequate prediction of the characteristics and behaviors of nanoscale materials in controlled environments, much less in biological systems, careful nanoparticle characterization should accompany biomedical applications of these materials. Informed correlations between adequately characterized nanomaterial properties and reliable biological endpoints are essential for guiding present and future researchers toward clinical nanotechnology-based solutions for cancer. Biological environments are notoriously dynamic; hence, nanoparticulate interactions within these environments will likely be comparatively diverse. For this reason, we recommend that an interactive and systematic approach to material characterization be taken when attempting to elucidate or measure biological interactions with nanoscale materials. We intend for this chapter to be a practical guide that could be used by researchers to identify key nanomaterial characteristics that require measurement for their systems and the appropriate techniques to perform those measurements. Each section includes a basic overview of each measurement and notes on how to address some of the common difficulties associated with nanomaterial characterization.

Cell death discrimination with Raman spectroscopy and support vector machines.

In the present study, Raman spectroscopy is employed to assess the potential toxicity of chemical substances. Having several advantages compared to other traditional methods, Raman spectroscopy is an ideal solution for investigating cells in their natural environment. In the present work, we combine the power of spectral resolution of Raman with one of the most widely used machine learning techniques. Support vector machines (SVMs) are used in the context of classification on a well established database. The database is constructed on three different classes: healthy cells, Triton X-100 (necrotic death), and etoposide (apoptotic death). SVM classifiers successfully assess the potential effect of the test toxins (Triton X-100, etoposide). The cells that are exposed to heat (45 degrees C) are tested using the classification rules obtained. It is shown that the heat effect results in apoptotic death, which is in agreement with existing literature.

Development of silica/vanadia/titania catalysts for removal of elemental mercury from coal-combustion flue gas.

SiO2/V2O5/TiO2 catalysts were synthesized for removing elemental mercury (Hg0) from simulated coal-combustion flue gas. Experiments were carried out in fixed-bed reactors using both pellet and powder catalysts. In contrast to the SiO2-TiO2 composites developed in previous studies, the V2O5 based catalysts do not need ultraviolet light activation and have higher Hg0 oxidation efficiencies. For Hg0 removal by SiO2-V2O5 catalysts, the optimal V2O5 loading was found between 5 and 8%, which may correspond to a maximum coverage of polymeric vanadates on the catalyst surface. Hg0 oxidation follows an Eley-Rideal mechanism where HCI, NO, and NO2 are first adsorbed on the V2O5 active sites and then react with gas-phase Hg0. HCI, NO, and NO2 promote Hg oxidation, while SO2 has an insignificant effect and water vapor inhibits Hgo oxidation. The SiO2-TiO2-V2O5 catalysts exhibit greater Hg0 oxidation efficiencies than SiO2-V2O5, may be because the V-O-Ti bonds are more active than the V-O-Si bonds. This superior oxidation capability is advantageous to power plants equipped with wet-scrubbers where oxidized Hg can be easily captured. The findings in this work revealed the importance of optimizing the composition and microstructures of SCR (selective catalytic reduction) catalysts for Hg0 oxidation in coal-combustion flue gas.

Exposure to copper nanoparticles causes gill injury and acute lethality in zebrafish (Danio rerio).

Increasing use of metallic nanomaterials is likely to result in release of these particles into aqueous environments; however, it is unclear if these materials present a hazard to aquatic organisms. Because some dissolution of metal particles will occur, it is important to distinguish effects of nanoparticulates from dissolved metals. To address this issue, acute toxicity of soluble copper and 80 nm copper nanoparticle suspensions were examined in zebrafish. The results demonstrate that nanocopper is acutely toxic to zebrafish, with a 48 h LC50 concentration of 1.5 mg/L. Rapid aggregation of copper nanoparticles occurred after suspension in water, resulting in 50-60% of added mass leaving the water column. While dissolution of particulate copper occurred, it was insufficient to explain the mortality in nanocopper exposures. Histological and biochemical analysis revealed that the gill was the primary target organ for nanocopper. To further investigate the effects of nanocopper on the gill, zebrafish were exposed to 100 microg/L of nanocopper or to the concentration of soluble copper matching that present due to dissolution of the particles. Under these conditions, nanocopper produced different morphological effects and global gene expression patterns in the gill than soluble copper, clearly demonstrating that the effects of nanocopper on gill are not mediated solely by dissolution.

Research strategies for safety evaluation of nanomaterials. Part VI. Characterization of nanoscale particles for toxicological evaluation.

To properly assign mechanisms or causes for toxic effects of nanoscale materials, their properties and characteristics both outside and within the biological environment must be well understood. Scientists have many tools for studying the size, shape, and surface properties of particulates outside of the physiological environment; however, it is difficult to measure many of these same properties in situ without perturbing the environment, leading to spurious findings. Characterizing nanoparticle systems in situ can be further complicated by an organism's active clearance, defense, and/or immune responses. As toxicologists begin to examine nanomaterials in a systematic fashion, there is consensus that a series of guidelines or recommended practices is necessary for basic characterization of nanomaterials. These recommended practices should be developed jointly by physical scientists skilled in nano characterization and biological scientists experienced in toxicology research. In this article, basic nanoparticle characterization techniques are discussed, along with the some of the issues and implications associated with measuring nanoparticle properties and their interactions with biological systems. Recommendations regarding how best to approach nanomaterial characterization include using proper sampling and measurement techniques, forming multidisciplinary teams, and making measurements as close to the biological action point as possible.

Adsorption enhancement mechanisms of silica-titania nanocomposites for elemental mercury vapor removal.

A novel nanocomposite that combines high-surface area silica with the photocatalytic properties of titania has been developed that allows for effective capture of elemental mercury vapor. The adsorption capability of the developed material has been found to improve after periods of photocatalytic oxidation. In this study, the mechanisms for adsorption enhancement were identified. BET nitrogen adsorption and mercury porosimetry were used to evaluate pore structure, and the results suggest that a decrease in contact angle was likely to be responsible for improved mercury capture over time. Contact angle measurements showed a significant change of more than 10 degrees, indicating greater attraction to mercury for the used pellets due to deposited mercuric oxide. ICP and TGA analyses showed that mercury was captured as both elemental mercury (Hg0) and mercuric oxide (HgO). In addition, it was shown that pellets used for nearly 500 h still showed greater than 90% removal efficiency and had an average capacity of 10 mg of Hg/g based on mass balance calculations, while some pellets had a capacity over 30 mg of Hg/g according to ICP and TGA analyses. Mercuric oxide doped pellets removed 100% of elemental mercury without pretreatment. The superior mercury removal efficiency combined with various advantages of the novel composite demonstrates its use as an effective alternative to conventional activated carbon injection technology.

An analytical model for the dissolution of different particle size samples of Bioglass in TRIS-buffered solution.

We analyzed the early stages of reactivity of three different particle size samples of Bioglass 45S5 and a bulk sample in TRIS-buffered solution at pH 8. Ion release, measured with ion-coupled plasma emission spectroscopy, and pH variations are reported. It was demonstrated that differences in the initial surface area influence the increase in pH, the rate of elemental release, and the rate of calcium phosphate reprecipitation. In particular, a thicker Ca/P layer was obtained on larger particles. The equilibrium value of Si in solution was independent of sample form and amount of sample dissolved, and was always close to the value observed when bulk silica is dissolved at pH 8. An analytical model is proposed for cation release, based on a two-step mechanism. It was found that the early stage of dissolution was nearly diffusion controlled for larger particles and bulk samples. The second stage was similar to a first-order homogeneous dissolution. The influence of sample surface area/solution volume ratio seemed to be more complex than that proposed in the early works presented in the literature. It is suggested that variation of surface area has a significant impact on the course of the dissolution.

Radiologic sciences. Faculty needs assessment.

A total of 326 programs are represented in the data collected. Based on the average number of full- and part-time faculty members reported per program, this survey represents more than 1500 faculty positions. Based on the forecast of retirement and career change for all faculty members, there will be a turnover of 700 to 800 positions over the next 5 to 10 years. Part-time/adjunct faculty vacancies are expected to create the greatest number of opportunities for technologists to make the transition to education, with approximately one third of current part-time/adjunct educators planning on leaving radiologic sciences education within 5 years. To encourage retention of part-time/adjunct educators, annual evaluations should be modified to recognize the important educational role these instructors play. There is a need to create enthusiasm and interest in education as a career pathway for radiologic technologists. Resources are needed that help radiologic technologists make the transition to teaching. Finally, the retention of educators must be emphasized. Program applicant trends indicate radiologic technology students are older, have prior postsecondary education experience or are making a career change. This data emphasizes the need for educators, both full time and part time, to understand the characteristics and needs of the adult learner. Adult learners bring a wealth of education, experience and life skills that create both opportunities and challenges in the classroom and clinical setting. All categories of respondents indicated that their current salaries were greater than those of program graduates in their firstjob. Of interest is that 1 in 5 (20%) of part-time/adjunct educators indicated the opposite--that program graduates earn more in their firstjob than educators earn. When asked about salaries if working full time in clinical practice, the majority of all groups indicated their salary would be about the same or would decrease. Only 20% of program directors, 21% of full-time educators and 26% of part-time/adjunct educators indicated their salary would be higher in clinical practice. Part-time/adjunct educators reported working the most in clinical practice within the past week to month. Program directors exhibited the greatest separation from clinical practice, with more than half indicating a gap of 2 years or more from practicing in the clinical environment. While academic achievement is common among the educator populations sampled, a very low percentage of these educators are seeking an advanced academic degree. Less than a third of those surveyed indicated that they were pursuing an advanced degree. Becoming involved in research is not a requirement for many current educators, although survey participants expressed an interest in information about how to conduct a research project. A primary motivator for conducting the faculty development needs assessment was to use the data in strategic planning to set priorities for the resources available to the ASRT Education Department. The data will help maximize ASRT support for present and future educators. Services created by the ASRT Education Department will deepen the relationship with this key segment of the professional community.

Effect of pH and ionic strength on the reactivity of Bioglass 45S5.

Bioglass 45S5 is a silica-based melt-derived glass, used in medical field as a bone regenerative material because of the deposition of a layer of hydroxy carbonate apatite (HCA) on the surface of the glass when immersed in body fluid. The present paper studies the early steps of reaction of 2-microm sized particles of Bioglass, in solutions buffered with TRIS at different pH, by means of ICP-ES and FTIR spectroscopy. Only at pH 8 could a total reconstruction of the glass be observed, with the formation of both a silica and a calcium phosphate rich layers. At higher pH, selective dissolution of the glass was hindered by the immediate precipitation of a layer of calcium phosphate, whereas at lower pH a total breakdown of the glass occurred and no calcium phosphate precipitation was noted. The use of the ATR-liquid cell allowed the observation of the reaction in real time, and this showed that the process of silica formation is not separable from cation leaching from the glass, as well as the formation of the calcium phosphate rich layer.