Evolution and Impact of a Diagnostic Point-of-Care Ultrasound Program in a PICU.

OBJECTIVES: To evaluate the impact of point-of-care ultrasound (POCUS) use on clinicians within a PICU and to assess infrastructural elements of our POCUS program development. DESIGN: Retrospective observational study. SETTING: Large academic, noncardiac PICU in the United States. SUBJECTS: Patients in a PICU who had diagnostic POCUS performed. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Between January 1, 2017, and December 31, 2022, 7201 diagnostic POCUS studies were ordered; 1930 (26.8%) had a quality assurance (QA) record generated in an independent POCUS QA database. The cardiac domain was most frequently imaged (81.0% of ordered studies, 81.2% of reviewed studies). POCUS images changed clinician understanding of pathophysiology in 563 of 1930 cases (29.2%); when this occurred, management was changed in 318 of 563 cases (56.5%). Cardiac POCUS studies altered clinician suspected pathophysiology in 30.1% of cases (472/1568), compared with 21.5% (91/362) in noncardiac studies (p = 0.06). Among cases where POCUS changed clinician understanding, management changed more often following cardiac than noncardiac POCUS (p = 0.02). Clinicians identified a need for cardiology consultation or complete echocardiograms in 294 of 1568 cardiac POCUS studies (18.8%). Orders for POCUS imaging increased by 94.9%, and revenue increased by 159.4%, from initial to final study year. QA database use by both clinicians and reviewers decreased annually as QA processes evolved in the setting of technologic growth and unit expansion. CONCLUSIONS: Diagnostic POCUS imaging in the PICU frequently yields information that alters diagnosis and changes management. As PICU POCUS use increased, QA processes evolved resulting in decreased use of our initial QA database. Modifications to QA processes are likely necessary as clinical contexts change over time.

Molecular Adsorbent Recirculating System for Acute Liver Failure in a New Pediatric-Based Extracorporeal Liver Support Program.

IMPORTANCE: Acute liver failure (ALF) carries significant morbidity and mortality, for both pediatric and adult patients. Albumin dialysis via the molecular adsorbent recirculating system (MARS) is a form of extracorporeal liver support (ELS) that can reduce hepatic encephalopathy (HE), a main driver of mortality in ALF. However, data on MARS and its benefit on mortality have been inconsistent. OBJECTIVES: We sought to report our experiences and patient outcomes from the first 2 years of operation of a new ELS program, within an established pediatric liver transplantation center. DESIGN SETTING AND PARTICIPANTS: Retrospective review of outcomes in pediatric and adult patients treated with MARS therapy for ALF, from 2021 to 2022. MAIN OUTCOMES AND MEASURES: Outcomes included reduction in HE and biochemical markers of ALF after MARS therapy, survival, and transplant-free survival. Comparisons were made via Wilcoxon signed-rank test. RESULTS: Five pediatric and two adult patients underwent MARS for ALF. Ages ranged from 2 to 29 years. Overall, 21 MARS runs were performed (median 3 runs per patient, 12.4 hr per run [interquartile range, IQR 10.1-17]). Overall survival was 85.7%, and transplant-free survival was 71.4%. There was a statistically significant reduction in HE score with MARS therapy (median 3 [IQR 3-4] to 1 [IQR 0-1], p = 0.03), and in ALF biomarkers including ammonia (256 µL/dL [195-265] to 75 µL/dL [58-101], p = 0.02), aspartate aminotransferase (6,362 U/L [920-8,305] to 212 U/L [72-431], p = 0.02), alanine aminotransferase (8,362 U/L [3,866-9,189] to 953 U/L [437-1,351], p = 0.02), and international normalized ratio (4.5 [3.3-6.7] to 1.3 [1.2-1.4], p = 0.02). CONCLUSIONS AND RELEVANCE: MARS therapy for ALF was well tolerated by both pediatric and adult patients, and resulted in significant improvement in clinical and biochemical parameters. We demonstrated encouraging overall and transplant-free survival, suggesting that early initiation of MARS with relatively long and frequent cycle times may be of significant benefit to ALF patients, and is worthy of additional study in larger cohorts.

A qualitative assessment of provider satisfaction and experiences with a COVID-19 community mobile health clinic outreach model in underserved Baltimore neighborhoods.

Objective: Although previous studies have assessed provider perceptions about telehealth, no prior studies have qualitatively assessed the experiences and satisfaction of health-care providers with a community mobile health clinic model within underserved urban settings. Methods: This study draws on the views expressed by community health workers (n = 4), registered nurses (n = 2), Grace Medical Center outreach specialists (n = 2), and physician assistants staffing LifeBridge Health's virtual hospital (n = 3) to understand their satisfaction and experiences with a COVID-19 community mobile health clinic in underserved Baltimore neighborhoods. Thematic analysis of the interviews was used to extract themes and subthemes of our health-care providers' experiences with the community mobile health clinic model. Results: These individuals shared their experiences addressing social determinants of health, the perceived impact of community mobile health clinic, satisfaction with and limitations of the pilot project, as well as future implications for the community mobile health clinic model. Finally, ideas for how the model can fit into the existing healthcare delivery framework are suggested. Conclusion: The context surrounding the COVID-19 pandemic has provided a unique opportunity to critically address healthcare frameworks and models. The LifeBridge community mobile health clinic served as an initiative to truly bridge together community outreach and health access. Among the many themes, health-care providers on the team applauded the model for its potential to bring preventative health care to the patient with the goal of improving patient health outcomes.

Single-Particle Insights into Plasmonic Hot Carrier Separation Augmenting Photoelectrochemical Ethanol Oxidation with Photocatalytically Synthesized Pd-Au Bimetallic Nanorods.

Understanding the nature of hot carrier pathways following surface plasmon excitation of heterometallic nanostructures and their mechanistic prevalence during photoelectrochemical oxidation of complex hydrocarbons, such as ethanol, remains challenging. This work studies the fate of carriers from Au nanorods before and after the presence of reductively photodeposited Pd at the single-particle level using scattering and emission spectroscopy, along with ensemble photoelectrochemical methods. A sub-2 nm epitaxial Pd0 shell was reductively grown onto colloidal Au nanorods via hot carriers generated from surface plasmon resonance excitation in the presence of [PdCl4]2-. These bimetallic Pd-Au nanorod architectures exhibited 14% quenched emission quantum yields and 9% augmented plasmon damping determined from their scattering spectra compared to the bare Au nanorods, consistent with injection/separation of intraband hot carriers into the Pd. Absorbed photon-to-current efficiency in photoelectrochemical ethanol oxidation was enhanced 50× from 0.00034% to 0.017% due to the photodeposited Pd. Photocurrent during ethanol oxidation improved 13× under solar-simulated AM1.5G and 40× for surface plasmon resonance-targeted irradiation conditions after photodepositing Pd, consistent with enhanced participation of intraband-excited sp-band holes and desorption of ethanol oxidation reaction intermediates owing to photothermal effects.

COVID-19 Testing and Social Determinants of Health Among Disadvantaged Baltimore Neighborhoods: A Community Mobile Health Clinic Outreach Model.

The objective was to summarize data on coronavirus disease 2019 (COVID-19) testing uptake, social determinants of health, and patient satisfaction with mobile health clinic services within underserved minority and low-income communities. This COVID-19 pilot project was conducted during June and July 2020 in low-income residential neighborhoods in West Baltimore, Maryland. Quantitative data were collected and assessed cross-sectionally. Demographically, 85% of the patients identified as Black or African American (n = 265) and 58.2% as female (n = 184). The COVID-19 test was administered by the registered nurse to 78.2% (n = 288) of the patients. More than 90% of patients confirmed high levels of satisfaction with the services they received from the community mobile health clinic. Social determinants were assessed and females reported significantly worse health literacy than their male counterparts (P < 0.05). Study findings suggest that the community mobile health clinic model was effective in attracting hard-to-reach and marginalized individuals, who otherwise may have gone untested or undiagnosed. This care delivery model can be one solution to disparities by improving access to COVID-19 testing and primary care for communities with higher vulnerability to COVID-19 complications.

Functionalized Phosphonium Cations Enable Zinc Metal Reversibility in Aqueous Electrolytes.

Aqueous rechargeable zinc metal batteries promise attractive advantages including safety, high volumetric energy density, and low cost; however, such benefits cannot be unlocked unless Zn reversibility meets stringent commercial viability. Herein, we report remarkable improvements on Zn reversibility in aqueous electrolytes when phosphonium-based cations are used to reshape interfacial structures and interphasial chemistries, particularly when their ligands contain an ether linkage. This novel aqueous electrolyte supports unprecedented Zn reversibility by showing dendrite-free Zn plating/stripping for over 6400 h at 0.5 mA cm-2 , or over 280 h at 2.5 mA cm-2 , with coulombic efficiency above 99 % even with 20 % Zn utilization per cycle. Excellent full cell performance is demonstrated with Na2 V6 O16 ⋅1.63 H2 O cathode, which cycles for 2000 times at 300 mA g-1 . The microscopic characterization and modeling identify the mechanism of unique interphase chemistry from phosphonium and its functionalities as the key factors responsible for dictating reversible Zn chemistry.

Proactively Connecting Residents in Underserved and Low Socioeconomic Status Communities with "Virtual Hospital" Telehealth Access in Response to the COVID-19 Pandemic.

This report from the field describes the uptake of a telemedicine outreach model among residents in under-resourced urban settings as a proactive response to the COVID-19 pandemic. We describe the methods and uptake of our telehealth virtual hospital program and implications for practice.

Formation of Brightly Luminescent MoS2 Nanoislands from Multilayer Flakes via Plasma Treatment and Laser Exposure.

A robust and reliable method for enhancing the photoluminescence (PL) of multilayer MoS2 is demonstrated using an oxygen plasma treatment process followed by laser exposure. Here, the plasma and laser treatments result in an indirect-to-direct band gap transition. The oxygen plasma creates a slight decoupling of the layers and converts some of the MoS2 to MoO3. Subsequent laser irradiation further oxidizes the MoS2 to MoO3, as confirmed via X-ray photoelectron spectroscopy, and results in localized regions of brightly luminescent MoS2 monolayer triangular islands as seen in high-resolution transmission electron microscopy images. The PL lifetimes are found to decrease from 494 to 190 ps after plasma and laser treatment, reflecting the smaller size of the MoS2 grains/regions. Atomic force microscopic imaging shows a 2 nm increase in thickness of the laser-irradiated regions, which provides further evidence of the MoS2 being converted to MoO3.

A Salt-Templated Synthesis Method for Porous Platinum-based Macrobeams and Macrotubes.

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.

Boosted Oxygen Evolution Reactivity by Igniting Double Exchange Interaction in Spinel Oxides.

A double-exchange interaction (DEI) was demonstrated to boost the oxygen evolution reaction (OER) in spinel oxides. DEI was ignited by synergistic actions of constructing nanoheterojunctions and creating oxygen vacancy (VO) in spinel NiCo2O4. DEI between octahedrally coordinated Ni and Co resulted in the generation of superior OER active centers Co(3-δ)+ and Ni3+. The multiple synergistic effects empower the electrocatalyst with exceptional OER activity, with an overpotential of 270 ± 3 mV at 10 mA/cm2 and a Tafel slope of 39 mV/dec, both of which are among the best values for NiCo2O4-based nanostructures, and even better than those for IrO2 and RuO2.

Photodeposition of Pd onto Colloidal Au Nanorods by Surface Plasmon Excitation.

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot electrons upon SPR irradiation drive reductive deposition of Pd on colloidal AuNR in the presence of [PdCl4]2-. Plasmon-driven reduction of secondary metals potentiates covalent, sub-wavelength deposition at targeted locations coinciding with electric field "hot-spots" of the plasmonic substrate using an external field (e.g., laser). The process described herein details a solution-phase deposition of a catalytically-active noble metal (Pd) from a transition metal halide salt (H2PdCl4) onto aqueously-suspended, anisotropic plasmonic structures (AuNR). The solution-phase process is amenable to making other bimetallic architectures. Transmission UV-vis monitoring of the photochemical reaction, coupled with ex situ XPS and statistical TEM analysis, provide immediate experimental feedback to evaluate properties of the bimetallic structures as they evolve during the photocatalytic reaction. Resonant plasmon irradiation of AuNR in the presence of [PdCl4]2- creates a thin, covalently-bound Pd0 shell without any significant dampening effect on its plasmonic behavior in this representative experiment/batch. Overall, plasmonic photodeposition offers an alternative route for high-volume, economical synthesis of optoelectronic materials with sub-5 nm features (e.g., heterometallic photocatalysts or optoelectronic interconnects).

Structure-Property-Performance Relationship of Ultrathin Pd-Au Alloy Catalyst Layers for Low-Temperature Ethanol Oxidation in Alkaline Media.

Pd-containing alloys are promising materials for catalysis. Yet, the relationship of the structure-property performance strongly depends on their chemical composition, which is currently not fully resolved. Herein, we present a physical vapor deposition methodology for developing PdxAu1-x alloys with fine control over the chemical composition. We establish direct correlations between the composition and these materials' structural and electronic properties with its catalytic activity in an ethanol (EtOH) oxidation reaction. By combining X-ray diffraction (XRD) and X-ray photelectron spectroscopy (XPS) measurements, we validate that the Pd content within both bulk and surface compositions can be finely controlled in an ultrathin-film regime. Catalytic oxidation of EtOH on the PdxAu1-x electrodes presents the largest forward-sweeping current density for x = 0.73 at ∼135 mA cm-2, with the lowest onset potential and largest peak activity of 639 A gPd-1 observed for x = 0.58. Density functional theory (DFT) calculations and XPS measurements demonstrate that the valence band of the alloys is completely dominated by Pd particularly near the Fermi level, regardless of its chemical composition. Moreover, DFT provides key insights into the PdxAu1-x ligand effect, with relevant chemisorption activity descriptors probed for a large number of surface arrangements. These results demonstrate that alloys can outperform pure metals in catalytic processes, with fine control of the chemical composition being a powerful tuning knob for the electronic properties and, therefore, the catalytic activity of ultrathin PdxAu1-x catalysts. Our high-throughput experimental methodology, in connection with DFT calculations, provides a unique foundation for further materials' discovery, including machine-learning predictions for novel alloys, the development of Pd-alloyed membranes for the purification of reformate gases, binder-free ultrathin electrocatalysts for fuel cells, and room temperature lithography-based development of nanostructures for optically driven processes.

Harvesting resonantly-trapped light for small molecule oxidation reactions at the Au/α-Fe2O3 interface.

Plasmonic metal nanoparticles (NPs) extend the overall light absorption of semiconductor materials. However, it is not well understood how coupling metal NPs to semiconductors alters the photo-electrochemical activity of small molecule oxidation (SMO) reactions. Different photo-anode electrodes comprised of Au NPs and α-Fe2O3 are designed to elucidate how the coupling plays not only a role in the water oxidation reaction (WO) but also performs for different SMO reactions. In this regard, Au NPs are inserted at specific regions within and/or on α-Fe2O3 layers created with a sequential electron beam evaporation method and multiple annealing treatments. The SMO and WO reactions are probed with broad-spectrum irradiation experiments with an emphasis on light-driven enhancements above and below the α-Fe2O3 band gap. Thin films of α-Fe2O3 supported on a gold back reflective layer resonantly-traps incident light leading to enhanced SMO/WO conversion efficiencies at high overpotential (η) for above band-gap excitations with no SMO activity observed at low η. In contrast, a substantial increase in the light-driven SMO activity is observed at low η, as well as for below band-gap excitations when sufficiently thin α-Fe2O3 films are decorated with Au NPs at the solution-electrode interface. The enhanced photo-catalytic activity is correlated with increased surface oxygen content (hydroxyl groups) at the Au/α-Fe2O3 interface, as well as simulated volume-integrated near-field enhancements over select regions of the Au/α-Fe2O3 interface providing an important platform for future SMO/WO photo-electrocatalyst development.

Medical retirement from sport after concussions: A practical guide for a difficult discussion.

PURPOSE OF REVIEW: In patients with a considerable history of sports-related concussion, the decision of when to discontinue participation in sports due to medical concerns including neurologic disorders has potentially life-altering consequences, especially for young athletes, and merits a comprehensive evaluation involving nuanced discussion. Few resources exist to aid the sports medicine provider. RECENT FINDINGS: In this narrative review, we describe 10 prototypical vignettes based upon the authors' collective experience in concussion management and propose an algorithm to help clinicians navigate retirement discussions. Issues for consideration include absolute and relative contraindications to return to sport, ranging from clinical or radiographic evidence of lasting neurologic injury to prolonged concussion recovery periods or reduced injury threshold to patient-centered factors including personal identity through sport, financial motivations, and navigating uncertainty in the context of long-term risks. SUMMARY: The authors propose a novel treatment algorithm based on real patient cases to guide medical retirement decisions after concussion in sport.

Effects of the New York State Concussion Management and Awareness Act ("Lystedt Law") on Concussion-Related Emergency Health Care Utilization Among Adolescents, 2005-2015.

BACKGROUND: All states have enacted legislation addressing the management of sports-related concussions (SRCs) in adolescent athletes. The effect of these laws on health care utilization is uncertain. Hypothesis/Purpose: The purpose was to evaluate the effects of New York's 2011 Concussion Management and Awareness Act ("Lystedt Law") on emergency department (ED) concussion health care visits (EDCHVs) and brain imaging utilization. It was hypothesized that New York concussion legislation would have a significant temporal effect on EDCHVs. STUDY DESIGN: Descriptive epidemiology study. METHODS: Using the New York State Department of Health Statewide Planning and Research Cooperative System (SPARCS) database, trends in EDCHVs from 2005 to 2015 were identified among 12- to 18-year-old patients, comprising 5,740,403 total ED visits. RESULTS: Overall, 208,024 EDCHVs, including 54,669 for an SRC, occurred during the study period. EDCHVs increased from 13,664 (2.74% of all ED visits) in 2005 to a peak of 21,374 (4.26%) in 2013, with greatest relative increases from 2008 to 2013. SRCs followed a similar trend: 3213 (0.64%) in 2005 to a peak of 6197 (1.24%) in 2013. Brain imaging utilization decreased by 5.3% for EDCHVs and 15.4% for SRCs (all comparisons year-by-year and for trends; P < .001). CONCLUSION: The period of greatest increases in EDCHVs and decreases in brain imaging utilization for SRCs preceded New York concussion legislation by several years, suggesting a minimal direct effect on emergency care-seeking behavior for concussions. Instead, increased public awareness of SRCs and imaging guidelines may have driven EDCHV trends and imaging practices.

Enhanced photocurrent from Photosystem I upon in vitro truncation of the antennae chlorophyll.

Current effects on climate change and dwindling fossil fuel reserves require new materials and methods to convert solar energy into a viable clean energy source. Recent progress in the direct conversion of light into photocurrent has been well documented using Photosystem I. In plants, PSI consists of a core complex and multiple light-harvesting complexes, denoted LHCI and LHCII. Most of the methods for isolating PSI from plants involve a selective, detergent solubilization from thylakoids followed by sucrose gradient density centrifugation. These processes isolate one variant of PSI with a specific ratio of Chl:P700. In this study, we have developed a simple and potentially scalable method for isolating multiple PSI variants using Hydroxyapatite chromatography, which has been well documented in other Photosystem I isolation protocols. By varying the wash conditions, we show that it is possible to change the Chl:P700 ratios. These different PSI complexes were cast into a PSI-Nafion-osmium polymer film that enabled their photoactivity to be measured. Photocurrent increases nearly 400% between highly washed and untreated solutions based on equal chlorophyll content. Importantly, the mild washing conditions remove peripheral Chl and some LHCI without inhibiting the photochemical activity of PSI as suggested by SDS-PAGE analysis. This result could indicate that more P700 could be loaded per surface area for biohybrid devices. Compared with other PSI isolations, this protocol also allows isolation of multiple PSI variants without loss of photochemical activity.

Engineering Photosystem I Complexes with Metal Oxide Binding Peptides for Bioelectronic Applications.

Conventional dye-sensitized solar cells comprise semiconducting anodes sensitized with complex synthetic organometallic dyes, a platinum counter electrode, and a liquid electrolyte. This work focuses on replacing synthetic dyes with a naturally occurring biological pigment-protein complex known as Photosystem I (PSI). Specifically, ZnO binding peptides (ZOBiP)-fused PSI subunits (ZOBiP-PsaD and ZOBiP-PsaE) and TiO2 binding peptides (TOBiP)-fused ferredoxin (TOBiP-Fd) have been produced recombinantly from Escherichia coli. The MOBiP-fused peptides have been characterized via western blotting, circular dichroism, MALDI-TOF, and cyclic voltammetry. ZOBiP-PSI subunits have been used to replace wild-type PsaD and PsaE, and TOBiP-Fd has been chemically cross-linked to the stromal hump of PSI. These MOBiP peptides and MOBiP-PSI complexes have been produced and incubated with various metal oxide nanoparticles, showing increased binding when compared to that of wild-type PSI complexes.

Photoelectrochemistry of photosystem I bound in nafion.

Developing a solid state Photosystem I (PSI) modified electrode is attractive for photoelectrochemical applications because of the quantum yield of PSI, which approaches unity in the visible spectrum. Electrodes are constructed using a Nafion film to encapsulate PSI as well as the hole-scavenging redox mediator Os(bpy)2Cl2. The photoactive electrodes generate photocurrents of 4 µA/cm(2) when illuminated with 1.4 mW/cm(2) of 676 nm band-pass filtered light. Methyl viologen (MV(2+)) is present in the electrolyte to scavenge photoelectrons from PSI in the Nafion film and transport charges to the counter electrode. Because MV(2+) is positively charged in both reduced and oxidized states, it is able to diffuse through the cation permeable channels of Nafion. Photocurrent is produced when the working electrode is set to voltages negative of the Os(3+)/Os(2+) redox potential. Charge transfer through the Nafion film and photohole scavenging at the PSI luminal surface by Os(bpy)2Cl2 depends on the reduction of Os redox centers to Os(2+) via hole scavenging from PSI. The optimal film densities of Nafion (10 µg/cm(2) Nafion) and PSI (100 µg/cm(2) PSI) are determined to provide the highest photocurrents. These optimal film densities force films to be thin to allow the majority of PSI to have productive electrical contact with the backing electrode.

Illicit and pharmaceutical drug consumption estimated via wastewater analysis. Part B: placing back-calculations in a formal statistical framework.

Concentrations of metabolites of illicit drugs in sewage water can be measured with great accuracy and precision, thanks to the development of sensitive and robust analytical methods. Based on assumptions about factors including the excretion profile of the parent drug, routes of administration and the number of individuals using the wastewater system, the level of consumption of a drug can be estimated from such measured concentrations. When presenting results from these 'back-calculations', the multiple sources of uncertainty are often discussed, but are not usually explicitly taken into account in the estimation process. In this paper we demonstrate how these calculations can be placed in a more formal statistical framework by assuming a distribution for each parameter involved, based on a review of the evidence underpinning it. Using a Monte Carlo simulations approach, it is then straightforward to propagate uncertainty in each parameter through the back-calculations, producing a distribution for instead of a single estimate of daily or average consumption. This can be summarised for example by a median and credible interval. To demonstrate this approach, we estimate cocaine consumption in a large urban UK population, using measured concentrations of two of its metabolites, benzoylecgonine and norbenzoylecgonine. We also demonstrate a more sophisticated analysis, implemented within a Bayesian statistical framework using Markov chain Monte Carlo simulation. Our model allows the two metabolites to simultaneously inform estimates of daily cocaine consumption and explicitly allows for variability between days. After accounting for this variability, the resulting credible interval for average daily consumption is appropriately wider, representing additional uncertainty. We discuss possibilities for extensions to the model, and whether analysis of wastewater samples has potential to contribute to a prevalence model for illicit drug use.

Comparative photoactivity and stability of isolated cyanobacterial monomeric and trimeric Photosystem I.

Photoactivity of native trimeric, and non-native monomeric Photosystem I (PSI) extracted from Thermosynechococcus elongatus is compared in a photoelectrochemical system. The PSI monomer is isolated by disassembling a purified PSI trimer using a freeze-thaw technique in presence of the short-chain surfactant, octylthioglucoside. Photoactive electrodes are constructed with PSI, functioning as both light absorber and charge-separator, embedded within a conductive polymer film. Despite structural differences between PSI trimers and monomers, electrodes cast with equal chlorophyll-a concentration generate similar photoactivities. Photoaction spectra show that all photocurrent derived from electrodes of PSI and conductive polymer originates solely from PSI with no photocurrent caused by redox mediators in the conductive polymer film. Longevity studies show that the two forms of PSI photodegrade at the same rate while exposed to equal intensities of 676 nm light. Direct photo-oxidation measurements indicate that PSI's monomeric form has fewer light harvesting antennae than trimer, and also shows energy sharing between monomeric subunits in the trimer. The structure of PSI is also found to impact cell performance when applying light at incident powers above 1.5 mW/cm(2) due to the reduced optical cross-section in the monomer, causing saturation at lower light intensities than the trimer.