Characterization of Springtail (Arrhopalites caecus) for Use in Soil Ecotoxicity Testing.

Springtails (subclass: Collembola) represent one of the most extensively studied invertebrate groups in soil ecotoxicology. This is because of their ease of laboratory culture, significant ecological role, and sensitivity to environmental contaminants. Folsomia candida (family: Isotomidae) is a globally widespread parthenogenetic species that is prevalent in laboratory toxicity testing with springtails. Conversely, Arrhopalites caecus (family: Arrhopalitidae), a parthenogenic globular springtail species, remains untested in soil ecotoxicology. This species is found in diverse habitats, including cave systems and forest leaf litter, and has a global distribution. The sensitivity of A. caecus to environmental contaminants, such as neonicotinoid insecticides, as well as its life history and optimal culturing conditions, are largely unknown. The present study describes the establishment of a pure A. caecus laboratory culture and characterization of its life cycle and culturing conditions. We assessed the sensitivity of A. caecus to various insecticides, including exposures to the neonicotinoid thiamethoxam in soil and through a novel feeding assay as well as to clothianidin and cyantraniliprole in spiked soil exposures. In 7- and 14-day exposures to thiamethoxam in agricultural soil, the 50% lethal concentration (LC50) values were determined to be 0.129 mg/kg dry weight and 0.010 mg/kg dry weight, respectively. The 14-day LC50 for exposure to thiamethoxam via spiked food was determined to be 0.307 mg/kg dry weight. In addition, the 28-day 50% effect concentration for inhibition of juvenile production from cyantraniliprole exposure in the same soil type was 0.055 mg/kg dry weight. Challenges encountered in using this species included susceptibility to mite infestation and low adult survival rates in the 28-day cyantraniliprole test. Environ Toxicol Chem 2024;00:1-16. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Sediment Toxicity Tests: A Critical Review of Their use in Environmental Regulations.

Sediments are an integral component of aquatic systems, linking multiple water uses, functions, and services. Contamination of sediments by chemicals is a worldwide problem, with many jurisdictions trying to prevent future pollution (prospective) and manage existing contamination (retrospective). The present review assesses the implementation of sediment toxicity testing in environmental regulations globally. Currently, the incorporation of sediment toxicity testing in regulations is most common in the European Union (EU), North America, and Australasian regions, with some expansion in Asia and non-EU Europe. Employing sediment toxicity testing in prospective assessments (i.e., before chemicals are allowed on the market) is most advanced and harmonized with pesticides. In the retrospective assessment of environmental risks (i.e., chemicals already contaminating sediments), regulatory sediment toxicity testing practices are applied inconsistently on the global scale. International harmonization of sediment toxicity tests is considered an asset and has been successful through the widespread adoption and deployment of Organisation for Economic Co-operation and Development guidelines. On the other hand, retrospective sediment assessments benefit from incorporating regional species and protocols. Currently used toxicity testing species are diverse, with temperate species being applied most often, whereas test protocols are insufficiently flexible to appropriately address the range of environmental contaminants, including nanomaterials, highly hydrophobic contaminants, and ionized chemicals. The ever-increasing and -changing pressures placed on aquatic resources are a challenge for protection and management efforts, calling for continuous sediment toxicity test method improvement to insure effective use in regulatory frameworks. Future developments should focus on including more subtle and specific toxicity endpoints (e.g., incorporating bioavailability-based in vitro tests) and genomic techniques, extending sediment toxicity testing from single to multispecies approaches, and providing a better link with ecological protection goals. Environ Toxicol Chem 2024;00:1-20. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

New insights into pesticide occurrence and multicompartmental monitoring strategies in stream ecosystems using periphyton and suspended sediment.

Streams are susceptible to pesticide pollutants which are transported outside of the intended area of application from surrounding agricultural fields. It is essential to monitor the occurrence and levels of pesticides in aquatic ecosystems to comprehend their effects on the aquatic environment. The common sampling strategy used for monitoring pesticides in stream ecosystems is through the collection and analysis of grab water samples. However, grab water sampling may not effectively monitor pesticides due to its limited ability to capture temporal and spatial variability, potentially missing fluctuations and uneven distribution of pesticides in aquatic environments. Monitoring using periphyton and sediment sampling may offer a more comprehensive approach by accounting for accumulative processes and temporal variations. Periphyton are a collective of microorganisms that grow on hard surfaces in aquatic ecosystems. They are responsive to chemical and biological changes in the environment, and therefore have the potential to act as a cost-effective, integrated sampling tool to monitor pesticide exposures in aquatic ecosystems. The objective of this study was to assess pesticides detected through periphyton, suspended sediment, and conventional grab water sampling methods and identify the matrix that offers a more comprehensive characterization of a stream's pesticide exposure profile. Ten streams across Southern Ontario were sampled in 2021 and 2022. At each stream site, water, sediment and periphyton, colonizing both artificial and natural substrates, were collected and analyzed for the presence of ~500 pesticides. Each of the three matrices detected distinctive pesticide exposure profiles. The frequency of detection in periphyton, sediment and water matrices were related to pesticides' log Kow and log Koc (P < 0.05). In addition, periphyton bioconcentrated 22 pesticides above levels observed in the ambient water. The bioconcentration factors of pesticides in periphyton can be predicted from their log Kow (simple linear regressions, P < 0.05). The results demonstrate that sediment and periphyton accumulate pesticides in stream environments. This highlights the importance of monitoring pesticide exposure using these matrices to ensure a complete and comprehensive characterization of exposure in stream ecosystems.

Nutritional, pharmacological, and sensory properties of maple syrup: A comprehensive review.

Maple syrup is a naturally sweet product consumed directly or introduced in the preparation of various maple-derived food products. Several studies have described the chemical isolation and identification of maple syrup compounds, with some presenting pharmacological properties. However, a detailed review on maple syrup nutritional properties has not been undertaken. This review presents detailed information about the nutritional, organoleptic, and pharmacological properties of maple syrup. Studies carried out on animal models and a limited number of human models emphasize the potential benefits of maple syrup as a substitute for refined sugars, indicating that it could contribute to improved metabolic health when used in moderation. However, further medical and nutritional health studies based on human health assessments are needed to better understand the mechanisms of action of the various components of maple syrup and its potential therapeutic properties to demonstrate a stronger justification for its consumption relative to refined sugars. In addition, we compare maple syrup and common sweeteners to provide a further critical perspective on the potential nutritional and health benefits of maple syrup.

An Assessment of the Toxicity of Pesticide Mixtures in Periphyton from Agricultural Streams to the Mayfly Neocloeon triangulifer.

Residual concentrations of pesticides are commonly found outside the intended area of application in Ontario's surface waters. Periphyton are a vital dietary component for grazing organisms in aquatic ecosystems but can also accumulate substantial levels of pesticides from the surrounding water. Consequently, grazing aquatic organisms are likely subjected to pesticide exposure through the consumption of pesticide-contaminated periphyton. The objectives of the present study were to determine if pesticides partition into periphyton in riverine environments across southern Ontario and, if so, to determine the toxicity of pesticides in periphyton when fed to the grazing mayfly Neocloeon triangulifer. Sites with low, medium, and high pesticide exposure based on historic water quality monitoring data were selected to incorporate a pesticide exposure gradient into the study design. Artificial substrate samplers were utilized to colonize periphyton in situ, which were then analyzed for the presence of approximately 500 pesticides. The results demonstrate that periphyton are capable of accumulating pesticides in agricultural streams. A novel 7-day toxicity test method was created to investigate the effects of pesticides partitioned into periphyton when fed to N. triangulifer. Periphyton collected from the field sites were fed to N. triangulifer and survival and biomass production recorded. Survival and biomass production significantly decreased when fed periphyton colonized in streams with catchments dominated by agricultural land use (p < 0.05). However, the relationship between pesticide concentration and survival or biomass production was not consistent. Using field-colonized periphyton allowed us to assess the dietary toxicity of environmentally relevant concentrations of pesticide mixtures; however, nutrition and taxonomic composition of the periphyton may vary between sites. Environ Toxicol Chem 2023;42:2143-2157. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Comparison of Established and Novel Insecticides on Survival and Reproduction of Folsomia candida.

Neonicotinoids have been among the most widely and abundantly used insecticides for most of the current century. The effects of these substances on nontarget terrestrial and aquatic organisms have resulted in a significant decrease in their use in many parts of the world. In response, the application of several novel classes of insecticides including diamides, ketoenols, pyridines, and butenolides has significantly increased. The hexapod subclass Collembola is an ecologically significant and widely distributed group of soil invertebrates often found in leaf litter and in surficial soils. We exposed the parthenogenic collembolan species Folsomia candida to six insecticides in a sandy loam soil for 28 days, including two neonicotinoids (thiamethoxam and clothianidin), a diamide (cyantraniliprole), a ketoenol (spirotetramat), a pyridine (flonicamid), and a butanolide (flupyradifurone) to assess the effect of each insecticide on survival and reproduction. Clothianidin, thiamethoxam, and cyantraniliprole (median effective concentration [EC50] values for reproduction: 0.19, 0.38, and 0.49 mg/kg soil, respectively) had a greater effect on survival and reproduction of F. candida than flupyradifurone, spirotetramat, and flonicamid (EC50 values for reproduction: 0.73, >3.08, and 5.20 mg/kg soil, respectively). All significant impacts found in our study were observed at concentrations below concentrations of the active ingredients that would be expected in agricultural soils. Environ Toxicol Chem 2023;42:1516-1528. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Cyanotoxins accumulate in Lake St. Clair fish yet their fillets are safe to eat.

Consuming fish exposed to cyanobacterial harmful algal blooms (HABs) may be a major route of microcystin toxin exposure to humans. However, it remains unknown whether fish can accumulate and retain microcystins temporally in waterbodies with recurring seasonal HABs, particularly before and after a HAB event when fishing is active. We conducted a field study on Largemouth Bass, Northern Pike, Smallmouth Bass, Rock Bass, Walleye, White Bass, and Yellow Perch to assess the human health risks to microcystin toxicity via fish consumption. We collected 124 fish in 2016 and 2018 from Lake St. Clair, a large freshwater ecosystem in the North American Great Lakes that is actively fished pre- and post-HAB periods. Muscles were analyzed using the 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) Lemieux Oxidation method for total microcystins, which was used to perform a human health risk assessment for comparison against fish consumption advisory benchmarks available for Lake St. Clair. From this collection 35 fish livers were additionally extracted to confirm the presence of microcystins. Microcystins were detected in all livers at widely varying concentrations (1-1500 ng g-1 ww), suggesting HABs are an underappreciated and pervasive stressor to fish populations. Conversely, microcystin levels were consistently low in muscles (0-15 ng g-1 ww) and presented negligible risk, empirically supporting that fillets may be safely consumed before and after HAB events following fish consumption advisories.

Revision of Failed Radial Head Arthroplasty.

BACKGROUND: Revision of radial head arthroplasty (RHA) may be indicated in cases of prosthesis loosening and malposition. Inherent difficulties in revision surgery include poor bone stock and disrupted soft tissue envelope. Although cases of RHA used for revision of failed RHA are rare, there is reasonable expectation for increasing frequency of these cases due to the increasing incidence of primary RHA. Furthermore, there is an increasing demand for postoperative recovery of function; thus, surgeons may consider revising a failed RHA to a new RHA. We report on series of failed RHA which were revised to a new radial head prosthesis. METHODS: A retrospective review was performed at multiple institutions for a single radial head prosthesis used for revision of a failed radial head prosthesis. Clinical and radiographic outcomes were collected with a minimum of 1 year of follow-up. RESULTS: Across 11 patients at a mean follow-up of 45.1 months, the mean Mayo Elbow Performance Score was 81.7; mean Disabilities of the Arm, Shoulder, and Hand scores were 24.4; and mean Visual Analog Scale for pain was 0.6. Radiographic analysis yielded no evidence of capitellar wear or stem loosening. CONCLUSION: A radial head prosthesis can produce satisfactory results when used for revision of a failed prosthesis. Inherent difficulties in revision surgery include the potential for reduced bone stock and a disrupted soft tissue envelope. Elements of prosthesis design which may contribute to effectively managing revision surgery include a long stem with in-growth surface and prosthetic head alignment to the axis of forearm rotation.

Lake Erie fish safe to eat yet afflicted by algal hepatotoxins.

Toxic harmful algal blooms (HABs) pose serious threats to human health and instances of wildlife death have been documented across taxa. However, the extent of toxicological impacts on wildlife species is largely unresolved, raising uncertainty about the repercussions of increasingly severe HABs on the biodiversity and functioning of aquatic ecosystems. Here, we conducted a field study to assess human health risks from consuming fish caught across all stages of a HAB and to determine the pervasiveness of potentially harmful levels of the cosmopolitan toxin microcystin on fish populations. We collected 190 fish in 2015 and 2017 from Lake Erie, a large freshwater ecosystem that is highly productive for fisheries and is an epicenter of HABs and microcystin toxicity events. Fish muscles and livers were analyzed for total microcystins, which was used to conduct a human health risk assessment for comparison against fish consumption advisory benchmarks available for Lake Erie. We found microcystins pose low risks to human health from fillet consumption (mean 1.80 ng g-1 ww) but substantial risks to fish health and recruitment from liver concentrations measured well before and after seasonal bloom events (mean 460.13 ng g-1 ww). Our findings indicate HABs are a previously underappreciated but pervasive threat to fish populations.

Improved cross-talk suppression for digitally enhanced interferometry using Golay complementary pairs.

We demonstrate digitally enhanced interferometry with better than 100 dB mean cross-talk suppression with Golay complementary pairs using a combination of numerical simulations and experiments. These results exceed previously reported cross-talk suppression using conventional maximal length sequences by more than 48 dB.

Are There Longitudinal Effects of Forest Harvesting on Carbon Quality and Flow and Methylmercury Bioaccumulation in Primary Consumers of Temperate Stream Networks?

Forest harvesting affects dissolved organic matter (DOM) and aqueous mercury inputs as well as the food web structure in small-headwater streams, but how these upstream changes manifest downstream is unclear. To address this uncertainty, we examined DOM quality, autochthony in the caddisfly Hydropsychidae (using δ2 H), and methylmercury (MeHg) concentrations in stream water and the caddisfly along a longitudinal gradient (first- to fourth-order streams, subcatchments of 50-1900 ha) in paired partially harvested and reference catchments in central Ontario, Canada. Although measures of DOM quality (specific ultraviolet absorbance at 254 nm 2.20-11.62) and autochthony in caddisflies (4.9%-34.0%) varied among sites, no upstream-to-downstream differences in these measures were observed between the paired harvested and reference catchments. In contrast, MeHg levels in stream water (0.06-0.35 ng/L) and caddisflies (29.7-192 µg/kg dry wt) were significantly higher in the upstream sites but not the farthest downstream sites in the harvested catchments compared to the reference catchments. This suggests that while current mitigation measures used by forestry companies did not prevent elevated MeHg in water and invertebrates at smaller spatial scales (subcatchments of 50-400 ha), these upstream impacts did not manifest at larger spatial scales (subcatchments of 800-1900 ha). The present study advances our understanding of spatially cumulative impacts within harvested catchments, which is critical to help forest managers maintain healthy forest streams and their provisioning of aquatic ecosystem services. Environ Toxicol Chem 2022;41:1490-1507. © 2022 SETAC.

Macrolides from rare actinomycetes: Structures and bioactivities.

Rare actinomycetes are a source of numerous diverse, biologically active secondary metabolites, including macrolides, which have been shown to display several antibiotic activities. The bioactivities and representative structures of 26 groups of macrolides from rare actinomycetes are presented in this review. The most interesting groups, with a wide range of biological activities, are ammocidins, bafilomycins, neomaclafungins, rosaramicins, spinosyns, and tiacumicins. Most macrolides are from the genus, Micromonospora, with smaller contributions from genera such as Saccharothrix, Amycolatopsis, Nocardiopsis and Catenulispora. These macrolides display unique cytotoxic, antibacterial, antifungal, antimicrobial, insecticidal, anti-trypanosomal, antimalarial, antiprotozoal, antimycobacterial and anti-herpetic activity. Considering their bioactivities and diverse structures, macrolides from rare actinomycetes warrant further investigation for future applications in medicine. This work highlights the bioactivities and structures of important classes of macrolides from rare actinomycetes that are already marketed or could be used in medicine in the future.

Fish tissue accumulation and proteomic response to microcystins is species-dependent.

Cyanotoxins including microcystins are increasing globally, escalating health risks to humans and wildlife. Freshwater fish can accumulate and retain microcystins in tissues; however, uptake and depuration studies thus far have not exposed fish to microcystins in its intracellular state (i.e., cell-bound or conserved within cyanobacteria), which is a primary route of exposure in the field, nor have they investigated sublethal molecular-level effects in tissues, limiting our knowledge of proteins responsible for microcystin toxicity pathways in pre-to-postsenescent stages of a harmful algal bloom. We address these gaps with a 2-wk study (1 wk of 'uptake' exposure to intracellular microcystins (0-40 µg L-1) produced by Microcystis aeruginosa followed by 1 wk of 'depuration' in clean water) using Rainbow Trout (Oncorhynchus mykiss) and Lake Trout (Salvelinus namaycush). Liver and muscle samples were collected throughout uptake and depuration phases for targeted microcystin quantification and nontargeted proteomics. For both species, microcystins accumulated at a higher concentration in the liver than muscle, and activated cellular responses related to oxidative stress, apoptosis, DNA repair, and carcinogenicity. However, intraspecific proteomic effects between Rainbow Trout and Lake Trout differed, and interspecific accumulation and retention of microcystins in tissues within each species also differed. We demonstrate that fish do not respond the same to cyanobacterial toxicity within and among species despite being reared in the same environment and diet.

The sustainable agriculture imperative: A perspective on the need for an agrosystem approach to meet the United Nations Sustainable Development Goals by 2030.

The development of modern, industrial agriculture and its high input-high output carbon energy model is rendering agricultural landscapes less resilient. The expected continued increase in the frequency and intensity of extreme weather events, in conjunction with declining soil health and biodiversity losses, could make food more expensive to produce. The United Nations has called for global action by establishing 17 sustainable development goals (SDGs), four of which are linked to food production and security: declining biodiversity (SDG 15), loss of ecosystem services and agroecosystem stability caused by increasing stress from food production intensification and climate change (SDG 13), declining soil health caused by agricultural practices (SDGs 2 and 6), and dependence on synthetic fertilizers and pesticides to maintain high productivity (SDG 2). To achieve these SDGs, the agriculture sector must take a leading role in reversing the many negative environmental trends apparent in today's agricultural landscapes to ensure that they will adapt and be resilient to climate change in 2030 and beyond. This will demand fundamental changes in how we practice agriculture from an environmental standpoint. Here, we present a perspective focused on the implementation of an agrosystem approach, which we define to promote regenerative agriculture, an integrative approach that provides greater resilience to a changing climate, reverses biodiversity loss, and improves soil health; honors Indigenous ways of knowing and a holistic approach to living off and learning from the land; and supports the establishment of emerging circular economies and community well-being. Integr Environ Assess Manag 2022;18:1199-1205. © 2021 SETAC.

Chemical composition and mineralogical residence of maple syrup: A comprehensive review.

Maple syrup is a sweet-tasting product prepared by boiling and concentrating the sap of sugar maple (Acer saccharum March). Because of its potential health benefits (except for people with diabetes and those with blood sugar problems), desirable flavor, and taste,maple syrup is one of most popular natural products in the world.Maple syrup fundamentally consists of both organic and inorganic components. The composition of maple syrup plays an important role in determining its flavour, smell, color, and distinguishes it from other sugar syrups. Maple syrup constituents have been identified by different analytical techniques typically based onspectroscopy or spectrometry. Herein, we present the first comprehensive review of all available information on the chemical composition and mineralogical residence of maple syrup collected from over 117 years of published literature.

Algebraic cancellation of inter-channel cross talk in multiplexed heterodyne interferometry.

We demonstrate the algebraic cancellation of residual phase cross talk in digitally enhanced heterodyne interferometry (DEHeI), a code division multiplexing technique for interferometric sensing. By using linear combinations of parallel decoding operations at multiple delays, we synthesize a zero correlation for spurious signals and remove phase cross talk: a method we call offset decoding. We experimentally demonstrate 70 dB of signal isolation and over 40 dB greater isolation than the equivalent standard implementation of DEHeI.

Cyanotoxins within and Outside of Microcystis aeruginosa Cause Adverse Effects in Rainbow Trout (Oncorhynchus mykiss).

The global expansion of toxic Microcystis blooms, and production of cyanotoxins including microcystins, are an increasing risk to freshwater fish. Differentiating intracellular and extracellular microcystin toxicity pathways (i.e., within and outside of cyanobacterial cells) in fish is necessary to assess the severity of risks to populations that encounter harmful algal blooms in pre-to-postsenescent stages. To address this, adult and juvenile Rainbow Trout (Oncorhynchus mykiss) were, respectively, exposed for 96 h to intracellular and extracellular microcystins (0, 20, and 100 µg L-1) produced by Microcystis aeruginosa. Fish were dissected at 24 h intervals for histopathology, targeted microcystin quantification, and nontargeted proteomics. Rainbow Trout accumulated intracellular and extracellular microcystins in all tissues within 24 h, with greater accumulation in the extracellular state. Proteomics revealed intracellular and extracellular microcystins caused sublethal toxicity by significantly dysregulating proteins linked to the cytoskeletal structure, stress responses, and DNA repair in all tissues. Pyruvate metabolism in livers, anion binding in kidneys, and myopathy in muscles were also significantly impacted. Histopathology corroborated these findings with evidence of necrosis, apoptosis, and hemorrhage at similar severity in both microcystin treatments. We demonstrate that sublethal concentrations of intracellular and extracellular microcystins cause adverse effects in Rainbow Trout after short-term exposure.

Deterministic risk assessment of firefighting water additives to terrestrial organisms.

Firefighting water additives are used to increase the rate at which fires can be extinguished. The majority of ecotoxicological research has focused on firefighting formulations containing perfluorinated compounds as additives, due to the persistence and bioaccumulative nature of the perfluorinated constituents. A number of relatively new additives have come on the market to replace the products containing perfluorinated compounds. The potential effect of these new additives on the environment has been largely unstudied. This study investigated the toxicity of six firefighting water additives: Eco-Gel™, ThermoGel 200L™, FireAde™, Fire-Brake™, Novacool Foam™, and F-500™ to terrestrial biota. Terrestrial organisms could be exposed to firefighting water additives through leaching into soil and/or runoff following a firefighting event or through direct aerial application during a forest fire. Toxicity to three plant species was assessed through seedling germination and emergence tests: Fagopyrum esculentum (buckwheat), Raphanus raphanistrum subsp. sativus (radish), and Rudbeckia hirta (black-eyed Susan). The effects of firefighting water additives on three soil invertebrates, the collembolan Folsomia candida, the earthworms Eisenia andrei, and Dendrodrilus rubidus, were also investigated using static acute tests to estimate EC50/LC50s. The concentration that resulted in a 50% reduction in survival (LC50) for the acute toxicity tests conducted with F. candida ranged from 3 (Eco-Gel) to 0.175% (Novacool) by volume. Comparatively, the acute toxicity of two firefighting water additives to D. rubidus could not be determined, as a 50% reduction in survival was not observed. A number of firefighting water additives were found to pose a hazard to terrestrial organisms based on a worst-case exposure scenario of direct application at the greatest recommended application rate for a class A fire (e.g., wood, paper). The firefighting water additive F-500 was found to pose a hazard (HQ ≥ 1) for all species tested, except for the acute test conducted with D. rubidus. Comparatively, Eco-Gel posed a hazard for only the acute and chronic tests with F. candida. This study represents the first comparative deterministic risk assessment of firefighting water additives to terrestrial ecosystems.

Optimization of an MMPB Lemieux Oxidation method for the quantitative analysis of microcystins in fish tissue by LC-QTOF MS.

Microcystins are toxic heptapeptides produced by cyanobacteria in marine and freshwater environments. In biological samples such as fish, microcystins can be found in the free form or covalently bound to protein phosphatases type I and II. Total microcystins in fish have been quantified in the past using the Lemieux Oxidation approach, where all toxins are oxidated to a common fragment (2-methyl-3-methoxy-4-phenylbutyric acid, MMPB) regardless of their initial amino acid configuration or form (free or protein bound). These studies have been carried out using different experimental conditions and employed different quantification strategies. The present study has further investigated the oxidation step using a systematic approach, to identify the most important factors leading to a higher, more robust MMPB generation yield from fish tissue in order to reduce the method detection limit. Field samples were quantified using an in-situ generated MMPB matrix matched calibration curve by isotope dilution with d3-MMPB via liquid chromatography coupled to time-of-flight mass spectrometry (LC-QTOF MS). This approach improves method's accuracy by taking into account of potential matrix effects that could affect the derivatization, sample prepation and instrumental analysis steps. The validated method showed 16.7% precision (RSD) and +6.7% accuracy (bias), with calculated method detection limits of 7.28 ng g-1 Performance of the method was assessed with the analysis of laboratory exposed Rainbow Trout (Oncorhynchus mykiss) to cyanobacteria as a positive control, where no microcystins were detected in the pre-exposure fish liver and fillet, low levels in the exposed fillet (65.0 ng g-1) and higher levels in the exposed liver (696 ng g-1). Finally, the method was employed for the analysis of 26 fillets (muscle) and livers of Walleye (Sander vitreus) and Yellow Perch (Perca flavescens) from Lake Erie, showing very low concentrations of microcystins in the fillet and higher concentrations in liver, up to 3720 ng g-1.

Fast beam steering with an optical phased array.

Optical phased arrays (OPAs) are devices that use the coherence of light to control the interference pattern in the far field, which enables them to steer a laser beam with no moving parts. As such, OPAs have potential applications in laser communications, target acquisition and tracking, metrology, and directed energy. In this Letter, we present a control architecture for an actively phase-locked OPA, capable of steering a laser beam at speeds limited by the actuation bandwidth of electro-optic modulators. The system achieved an output phase stability of λ/770 and steering speeds up to 1 MHz. The digital control architecture can be extended to GHz steering speeds, is readily scalable to hundreds of emitters, and is compatible with high-power arrays.