Ultrafast Nanodrum-on-Chip Pixels.

Environmentally friendly, ultrafast display pixels of micrometer sizes are fabricated with nanometer-thick gold films and Si/SiO2 wafers. The color displayed is due to both the plasmon response of the gold film and the optical interference from the Fabry-Peerot cavity formed by the underlying silicon substrate, the semitransparent gold film and the air gap between them. When an electric potential is applied to the gold film, the electrostatic force induces an attraction between the gold film and the silicon wafer. Due to the flexibility of the film, the size of the air gap changes, resulting in a changing color. By applying different driving signals, we have achieved cyan, magenta, and yellow reflected colors. The maximum switching rate of the pixel is primarily determined by the thickness dependence of the metal drum and its Young's modulus and is typically in the MHz regime.

Optical Cavity Design and Functionality for Molecular Strong Coupling.

Optical cavity/molecule strong coupling offers attractive opportunities to modulate photochemical or photophysical processes. When atoms or molecules are placed in an optical cavity, they can coherently exchange photonic energy with optical cavity vacuum fields, entering the strong coupling interaction regime. Recent work suggests that the thermodynamic and kinetic properties of molecules can be significantly changed by strong coupling, resulting in the emergence of intriguing photochemical and photophysical phenomena. As more and more physico-chemical systems are studied under strong coupling conditions, optical cavities have also advanced in their sophistication, responsiveness, and (multi)functionality. In this review, we highlight some of these recent developments, particularly focusing on Fabry-Perot microcavities.

Association of delayed adequate antimicrobial treatment and organ dysfunction in pediatric bloodstream infections.

BACKGROUND: Bloodstream infections (BSIs) are associated with significant mortality and morbidity, including multiple organ dysfunction. We explored if delayed adequate antimicrobial treatment for children with BSIs is associated with change in organ dysfunction as measured by PELOD-2 scores. METHODS: We conducted a multicenter, retrospective cohort study of critically ill children <18 years old with BSIs. The primary outcome was change in PELOD-2 score between days 1 (index blood culture) and 5. The exposure variable was delayed administration of adequate antimicrobial therapy by ≥3 h from blood culture collection. We compared PELOD-2 score changes between those who received early and delayed treatment. RESULTS: Among 202 children, the median (interquartile range) time to adequate antimicrobial therapy was 7 (0.8-20.1) hours; 124 (61%) received delayed antimicrobial therapy. Patients who received early and delayed treatment had similar baseline characteristics. There was no significant difference in PELOD-2 score changes from days 1 and 5 between groups (PELOD-2 score difference -0.07, 95% CI -0.92 to 0.79, p = 0.88). CONCLUSIONS: We did not find an association between delayed adequate antimicrobial therapy and PELOD-2 score changes between days 1 and 5 from detection of BSI. PELOD-2 score was not sensitive for clinical effects of delayed antimicrobial treatment. IMPACT: In critically ill children with bloodstream infections, there was no significant change in organ dysfunction as measured by PELOD-2 scores between patients who received adequate antimicrobial therapy within 3 h of their initial positive blood culture and those who started after 3 h. Higher PELOD-2 scores on day 1 were associated with larger differences in PELOD-2 scores between days 1 and 5 from index positive blood cultures. Further study is required to determine if PELOD-2 or alternative measures of organ dysfunction could be used as primary outcome measures in trials of antimicrobial interventions in pediatric critical care research.

A Shear-Thinning, Self-Healing, Dual-Cross Linked Hydrogel Based on Gelatin/Vanillin/Fe3+ /AGP-AgNPs: Synthesis, Antibacterial, and Wound-Healing Assessment.

A shear-thinning and self-healing hydrogel based on a gelatin biopolymer is synthesized using vanillin and Fe3+ as dual crosslinking agents. Rheological studies indicate the formation of a strong gel found to be injectable and exhibit rapid self-healing (within 10 min). The hydrogels also exhibited a high degree of swelling, suggesting potential as wound dressings since the absorption of large amounts of wound exudate, and optimum moisture levels, lead to accelerated wound healing. Andrographolide, an anti-inflammatory natural product is used to fabricate silver nanoparticles, which are characterized and composited with the fabricated hydrogels to imbue them with anti-microbial activity. The nanoparticle/hydrogel composites exhibit activity against Escherichia coli, Staphylococcus aureus, and Burkholderia pseudomallei, the pathogen that causes melioidosis, a serious but neglected disease affecting southeast Asia and northern Australia. Finally, the nanoparticle/hydrogel composites are shown to enhance wound closure in animal models compared to the hydrogel alone, confirming that these hydrogel composites hold great potential in the biomedical field.

Using metabolomics to predict severe traumatic brain injury outcome (GOSE) at 3 and 12 months.

BACKGROUND: Prognostication is very important to clinicians and families during the early management of severe traumatic brain injury (sTBI), however, there are no gold standard biomarkers to determine prognosis in sTBI. As has been demonstrated in several diseases, early measurement of serum metabolomic profiles can be used as sensitive and specific biomarkers to predict outcomes. METHODS: We prospectively enrolled 59 adults with sTBI (Glasgow coma scale, GCS ≤ 8) in a multicenter Canadian TBI (CanTBI) study. Serum samples were drawn for metabolomic profiling on the 1st and 4th days following injury. The Glasgow outcome scale extended (GOSE) was collected at 3- and 12-months post-injury. Targeted direct infusion liquid chromatography-tandem mass spectrometry (DI/LC-MS/MS) and untargeted proton nuclear magnetic resonance spectroscopy (1H-NMR) were used to profile serum metabolites. Multivariate analysis was used to determine the association between serum metabolomics and GOSE, dichotomized into favorable (GOSE 5-8) and unfavorable (GOSE 1-4), outcomes. RESULTS: Serum metabolic profiles on days 1 and 4 post-injury were highly predictive (Q2 > 0.4-0.5) and highly accurate (AUC > 0.99) to predict GOSE outcome at 3- and 12-months post-injury and mortality at 3 months. The metabolic profiles on day 4 were more predictive (Q2 > 0.55) than those measured on day 1 post-injury. Unfavorable outcomes were associated with considerable metabolite changes from day 1 to day 4 compared to favorable outcomes. Increased lysophosphatidylcholines, acylcarnitines, energy-related metabolites (glucose, lactate), aromatic amino acids, and glutamate were associated with poor outcomes and mortality. DISCUSSION: Metabolomic profiles were strongly associated with the prognosis of GOSE outcome at 3 and 12 months and mortality following sTBI in adults. The metabolic phenotypes on day 4 post-injury were more predictive and significant for predicting the sTBI outcome compared to the day 1 sample. This may reflect the larger contribution of secondary brain injury (day 4) to sTBI outcome. Patients with unfavorable outcomes demonstrated more metabolite changes from day 1 to day 4 post-injury. These findings highlighted increased concentration of neurobiomarkers such as N-acetylaspartate (NAA) and tyrosine, decreased concentrations of ketone bodies, and decreased urea cycle metabolites on day 4 presenting potential metabolites to predict the outcome. The current findings strongly support the use of serum metabolomics, that are shown to be better than clinical data, in determining prognosis in adults with sTBI in the early days post-injury. Our findings, however, require validation in a larger cohort of adults with sTBI to be used for clinical practice.

Molecular Chemistry in Cavity Strong Coupling.

The coherent exchange of energy between materials and optical fields leads to strong light-matter interactions and so-called polaritonic states with intriguing properties, halfway between light and matter. Two decades ago, research on these strong light-matter interactions, using optical cavity (vacuum) fields, remained for the most part the province of the physicist, with a focus on inorganic materials requiring cryogenic temperatures and carefully fabricated, high-quality optical cavities for their study. This review explores the history and recent acceleration of interest in the application of polaritonic states to molecular properties and processes. The enormous collective oscillator strength of dense films of organic molecules, aggregates, and materials allows cavity vacuum field strong coupling to be achieved at room temperature, even in rapidly fabricated, highly lossy metallic optical cavities. This has put polaritonic states and their associated coherent phenomena at the fingertips of laboratory chemists, materials scientists, and even biochemists as a potentially new tool to control molecular chemistry. The exciting phenomena that have emerged suggest that polaritonic states are of genuine relevance within the molecular and material energy landscape.

SERS Endoscopy for Monitoring Intracellular Drug Dynamics.

Understanding the dynamics and distribution of medicinal drugs in living cells is essential for the design and discovery of treatments. The tools available for revealing this information are, however, extremely limited. Here, we report the application of surface-enhanced Raman scattering (SERS) endoscopy, using plasmonic nanowires as SERS probes, to monitor the intracellular fate and dynamics of a common chemo-drug, doxorubicin, in A549 cancer cells. The unique spatio-temporal resolution of this technique reveals unprecedented information on the mode of action of doxorubicin: its localization in the nucleus, its complexation with medium components, and its intercalation with DNA as a function of time. Notably, we were able to discriminate these factors for the direct administration of doxorubicin or the use of a doxorubicin delivery system. The results reported here show that SERS endoscopy may have an important future role in medicinal chemistry for studying the dynamics and mechanism of action of drugs in cells.

Molecular Energy Transfer under the Strong Light-Matter Interaction Regime.

Research into strong light-matter interactions continues to fascinate, being spurred on by unforeseen and often spectacular experimental observations. Properties that were considered to depend exclusively on material composition have been found to be drastically altered when a material is placed inside a resonant optical cavity. This is nowhere more the case than in the field of intermolecular energy transfer, where polaritonic states formed as a result of strong light-matter interactions have been shown to promote energy transfer over distances vastly exceeding conventional limits. In this review, we provide the reader with a succinct account of the fundamental concepts of intermolecular energy transfer, and how they are modified by strong light-matter interactions. We also summarize recent experimental advances in the area, including in optoelectronic device contexts, and highlight both the potential and challenges that remain in this exciting field of research going forward.

Spectroelectrochemistry of CdSe/CdxZn1-xS Nanoplatelets.

We report an unexpected enhancement of photoluminescence (PL) in CdSe-based core/shell nanoplatelets (NPLs) upon electrochemical hole injection. Moderate hole doping densities induce an enhancement of more than 50% in PL intensity. This is accompanied by a narrowing and blue-shift of the PL spectrum. Simultaneous, time-resolved PL experiments reveal a slower luminescence decay. Such hole-induced PL brightening in NPLs is in stark contrast to the usual observation of PL quenching of CdSe-based quantum dots following hole injection. We propose that hole injection removes surface traps responsible for the formation of negative trions, thereby blocking nonradiative Auger processes. Continuous photoexcitation causes the enhanced PL intensity to decrease back to its initial level, indicating that photocharging is a key step leading to loss of PL luminescence during normal aging. Modulating the potential can be used to reversibly enhance or quench the PL, which enables electro-optical switching.

Formation of extramembrane ß-strands controls dimerization of transmembrane helices in amyloid precursor protein C99.

The 99-residue C-terminal domain of amyloid precursor protein (APP-C99), precursor to amyloid beta (Aß), is a transmembrane (TM) protein containing intrinsically disordered N- and C-terminal extramembrane domains. Using molecular dynamics (MD) simulations, we show that the structural ensemble of the C99 monomer is best described in terms of thousands of states. The C99 monomer has a propensity to form ß-strand in the C-terminal extramembrane domain, which explains the slow spin relaxation times observed in paramagnetic probe NMR experiments. Surprisingly, homodimerization of C99 not only narrows the conformational ensemble from thousands to a few states through the formation of metastable ß-strands in extramembrane domains but also stabilizes extramembrane α-helices. The extramembrane domain structure is observed to dramatically impact the homodimerization motif, resulting in the modification of TM domain conformations. Our study provides an atomic-level structural basis for communication between the extramembrane domains of the C99 protein and TM homodimer formation. This finding could serve as a general model for understanding the influence of disordered extramembrane domains on TM protein structure.

Criterion validity of the brief test of adult cognition by telephone (BTACT) for mild traumatic brain injury.

OBJECTIVES: There is a growing demand for remote assessment options for measuring cognition after mild traumatic brain injury (mTBI). The current study evaluated the criterion validity of the Brief Test of Adult Cognition by Telephone (BTACT) in distinguishing between adults with mTBI and trauma controls (TC) who sustained injuries not involving the head or neck. METHODS: The BTACT was administered to the mTBI (n = 46) and TC (n = 35) groups at 1-2 weeks post-injury. Participants also completed the Rivermead Post Concussion Symptoms Questionnaire. RESULTS: The BTACT global composite score did not significantly differ between the groups (t(79) = -1.04, p = 0.30); the effect size was small (d = 0.23). In receiver operating characteristic curve analyses, the BTACT demonstrated poor accuracy in differentiating between the groups (AUC = 0.567, SE = 0.065, 95% CI [0.44, 0.69]). The BTACT's ability to discriminate between mTBI and TCs did not improve after excluding mTBI participants (n = 15) who denied ongoing cognitive symptoms (AUC = 0.567, SE = 0.072, 95% CI [0.43, 0.71]). CONCLUSIONS: The BTACT may lack sensitivity to subacute cognitive impairment attributable to mTBI (i.e., not explained by bodily pain, post-traumatic stress, and other nonspecific effects of injury).

Antibiotic treatment duration for bloodstream infections in critically ill children-A survey of pediatric infectious diseases and critical care clinicians for clinical equipoise.

OBJECTIVE: To describe antibiotic treatment durations that pediatric infectious diseases (ID) and critical care clinicians usually recommend for bloodstream infections in critically ill children. DESIGN: Anonymous, online practice survey using five common pediatric-based case scenarios of bloodstream infections. SETTING: Pediatric intensive care units in Canada, Australia and New Zealand. PARTICIPANTS: Pediatric intensivists, nurse practitioners, ID physicians and pharmacists. MAIN OUTCOME MEASURES: Recommended treatment durations for common infectious syndromes associated with bloodstream infections and willingness to enrol patients into a trial to study treatment duration. RESULTS: Among 136 survey respondents, most recommended at least 10 days antibiotics for bloodstream infections associated with: pneumonia (65%), skin/soft tissue (74%), urinary tract (64%) and intra-abdominal infections (drained: 90%; undrained: 99%). For central vascular catheter-associated infections without catheter removal, over 90% clinicians recommended at least 10 days antibiotics, except for infections caused by coagulase negative staphylococci (79%). Recommendations for at least 10 days antibiotics were less common with catheter removal. In multivariable linear regression analyses, lack of source control was significantly associated with longer treatment durations (+5.2 days [95% CI: 4.4-6.1 days] for intra-abdominal infections and +4.1 days [95% CI: 3.8-4.4 days] for central vascular catheter-associated infections). Most clinicians (73-95%, depending on the source of bloodstream infection) would be willing to enrol patients into a trial of shorter versus longer antibiotic treatment duration. CONCLUSIONS: The majority of clinicians currently recommend at least 10 days of antibiotics for most scenarios of bloodstream infections in critically ill children. There is practice heterogeneity in self-reported treatment duration recommendations among clinicians. Treatment durations were similar across different infectious syndromes. Under appropriate clinical conditions, most clinicians would be willing to enrol patients into a trial of shorter versus longer treatment for common syndromes associated with bloodstream infections.

Anode Catalysts in Anion-Exchange-Membrane Electrolysis without Supporting Electrolyte: Conductivity, Dynamics, and Ionomer Degradation.

Anion-exchange-membrane water electrolyzers (AEMWEs) in principle operate without soluble electrolyte using earth-abundant catalysts and cell materials and thus lower the cost of green H2 . Current systems lack competitive performance and the durability needed for commercialization. One critical issue is a poor understanding of catalyst-specific degradation processes in the electrolyzer. While non-platinum-group-metal (non-PGM) oxygen-evolution catalysts show excellent performance and durability in strongly alkaline electrolyte, this has not transferred directly to pure-water AEMWEs. Here, AEMWEs with five non-PGM anode catalysts are built and the catalysts' structural stability and interactions with the alkaline ionomer are characterized during electrolyzer operation and post-mortem. The results show catalyst electrical conductivity is one key to obtaining high-performing systems and that many non-PGM catalysts restructure during operation. Dynamic Fe sites correlate with enhanced degradation rates, as does the addition of soluble Fe impurities. In contrast, electronically conductive Co3 O4 nanoparticles (without Fe in the crystal structure) yield AEMWEs from simple, standard preparation methods, with performance and stability comparable to IrO2 . These results reveal the fundamental dynamic catalytic processes resulting in AEMWE device failure under relevant conditions, demonstrate a viable non-PGM catalyst for AEMWE operation, and illustrate underlying design rules for engineering anode catalyst/ionomer layers with higher performance and durability.

Andrographolide stabilized-silver nanoparticles overcome ceftazidime-resistant Burkholderia pseudomallei: study of antimicrobial activity and mode of action.

Burkholderia pseudomallei (B. pseudomallei) is a Gram-negative pathogen that causes melioidosis, a deadly but neglected tropical disease. B. pseudomallei is intrinsically resistant to a growing list of antibiotics, and alternative antimicrobial agents are being sought with urgency. In this study, we synthesize andrographolide-stabilized silver nanoparticles (andro-AgNPs, spherically shaped with 16 nm average diameter) that show excellent antimicrobial activity against B. pseudomallei, including ceftazidime-resistant strains, being 1-3 orders of magnitude more effective than ceftazidime and 1-2 orders of magnitude more effective than other green-synthesized AgNPs. The andro-AgNPs are meanwhile non-toxic to mammalian cell lines. The mode of action of Andro-AgNPs toward B. pseudomallei is unraveled by killing kinetics, membrane neutralization, silver ions (Ag+) release, reactive oxygen species (ROS) induction, membrane integrity, and cell morphology change studies. The antimicrobial activity and mode of action of andro-AgNPs against B. pseudomallei reported here may pave the way to alternative treatments for melioidosis.

Autotuning of Vibrational Strong Coupling for Site-Selective Reactions.

Site-selective chemistry opens new paths for the synthesis of technologically important molecules. When a reactant is placed inside a Fabry-Perot (FP) cavity, energy exchange between molecular vibrations and resonant cavity photons results in vibrational strong coupling (VSC). VSC has recently been implicated in modified chemical reactivity at specific reactive sites. However, as a reaction proceeds inside an FP cavity, the refractive index of the reaction solution changes, detuning the cavity mode away from the vibrational mode and weakening the VSC effect. Here we overcome this issue, developing actuatable FP cavities to allow automated tuning of cavity mode energy to maintain maximized VSC during a reaction. As an example, the site-selective reaction of the aldehyde over the ketone in 4-acetylbenzaldehyde is achieved by automated cavity tuning to maintain optimal VSC of the ketone carbonyl stretch during the reaction. A nearly 50 % improvement in site-selective reactivity is observed compared to an FP cavity with static mirrors, demonstrating the utility of actuatable FP cavities as microreactors for organic chemistry.

Noninferiority Margin Size and Acceptance of Trial Results: Contingent Valuation Survey of Clinician Preferences for Noninferior Mortality.

OBJECTIVES: We used modified contingent valuation methodology to determine how noninferiority margin sizes influence clinicians' willingness to accept clinical trial results that compare mortality in critically ill children. METHODS: We surveyed pediatric infectious diseases and critical care clinicians in Canada, Australia, and New Zealand and randomized respondents to review 1 of 9 mock abstracts describing a noninferiority trial of bacteremic critically ill children assigned to 7 or 14 d of antibiotics. Each scenario showed higher mortality in the 7-d group but met noninferiority criterion. We explored how noninferiority margins and baseline mortality rates influenced respondent acceptance of results. RESULTS: There were 106 survey respondents: 65 (61%) critical care clinicians, 28 (26%) infectious diseases physicians, and 13 (12%) pharmacists. When noninferiority margins were 5% and 10%, 73% (24/33) and 79% (27/33) respondents would accept shorter treatment, compared with 44% (17/39) when the margin was 20% (P = 0.003). Logistic regression adjusted for baseline mortality showed 5% and 10% noninferiority margins were more likely to be associated with acceptance of shorter treatment compared with 20% margins (odds ratio [OR] 3.5, 95% confidence interval [CI]: 1.3-9.6, P = 0.013; OR 5.1, 95% CI: 1.8-14.6, P = 0.002). Baseline mortality was not a significant predictor of acceptance of shorter treatment. CONCLUSIONS: Clinicians are more likely to accept shorter treatment when noninferiority margins are ≤10%. However, nearly half of respondents who reviewed abstracts with 20% margins were still willing to accept shorter treatment. This is a novel application of contingent valuation methodology to elicit acceptance of research results among end users of the medical literature. HIGHLIGHTS: Clinicians are more likely to accept shorter treatment durations based on noninferior mortality results when the noninferiority margin is 5% or 10% than if the margin is 20%.However, nearly half of clinicians would still accept shorter-duration treatment as noninferior with margins of 20%.Baseline mortality does not independently predict acceptance of shorter-duration treatment.Contingent valuation is a novel approach to elicit the acceptance of research design parameters from the perspective of endusers of the medical literature.

Three-Electrode Study of Electrochemical Ionomer Degradation Relevant to Anion-Exchange-Membrane Water Electrolyzers.

Among existing water electrolysis (WE) technologies, anion-exchange-membrane water electrolyzers (AEMWEs) show promise for low-cost operation enabled by the basic solid-polymer electrolyte used to conduct hydroxide ions. The basic environment within the electrolyzer, in principle, allows the use of non-platinum-group metal catalysts and less-expensive cell components compared to acidic-membrane systems. Nevertheless, AEMWEs are still underdeveloped, and the degradation and failure modes are not well understood. To improve performance and durability, supporting electrolytes such as KOH and K2CO3 are often added to the water feed. The effect of the anion interactions with the ionomer membrane (particularly other than OH-), however, remains poorly understood. We studied three commercial anion-exchange ionomers (Aemion, Sustainion, and PiperION) during oxygen evolution (OER) at oxidizing potentials in several supporting electrolytes and characterized their chemical stability with surface-sensitive techniques. We analyzed factors including the ionomer conductivity, redox potential, and pH tolerance to determine what governs ionomer stability during OER. Specifically, we discovered that the oxidation of Aemion at the electrode surface is favored in the presence of CO32-/HCO3- anions perhaps due to the poor conductivity of that ionomer in the carbonate/bicarbonate form. Sustainion tends to lose its charge-carrying groups as a result of electrochemical degradation favored in basic electrolytes. PiperION seems to be similarly negatively affected by a pH drop and low carbonate/bicarbonate conductivity under the applied oxidizing potential. The insight into the interactions of the supporting electrolyte anions with the ionomer/membrane helps shed light on some of the degradation pathways possible inside of the AEMWE and enables the informed design of materials for water electrolysis.

Antimicrobial treatment duration for uncomplicated bloodstream infections in critically ill children: a multicentre observational study.

BACKGROUND: Bloodstream infections (BSIs) cause significant morbidity and mortality in critically ill children but treatment duration is understudied. We describe the durations of antimicrobial treatment that critically ill children receive and explore factors associated with treatment duration. METHODS: We conducted a retrospective observational cohort study in six pediatric intensive care units (PICUs) across Canada. Associations between treatment duration and patient-, infection- and pathogen-related characteristics were explored using multivariable regression analyses. RESULTS: Among 187 critically ill children with BSIs, the median duration of antimicrobial treatment was 15 (IQR 11-25) days. Median treatment durations were longer than two weeks for all subjects with known sources of infection: catheter-related 16 (IQR 11-24), respiratory 15 (IQR 11-26), intra-abdominal 20 (IQR 14-26), skin/soft tissue 17 (IQR 15-33), urinary 17 (IQR 15-35), central nervous system 33 (IQR 15-46) and other sources 29.5 (IQR 15-55) days. When sources of infection were unclear, the median duration was 13 (IQR 10-16) days. Treatment durations varied widely within and across PICUs. In multivariable linear regression, longer treatment durations were associated with severity of illness (+ 0.4 days longer [95% confidence interval (CI), 0.1 to 0.7, p = 0.007] per unit increase in PRISM-IV) and central nervous system infection (+ 17 days [95% CI, 6.7 to 27.4], p = 0.001). Age and pathogen type were not associated with treatment duration. CONCLUSIONS: Most critically ill children with BSIs received at least two weeks of antimicrobial treatment. Further study is needed to determine whether shorter duration therapy would be effective for selected critically ill children.

Comparison of Intracranial Pressure Measurements Before and After Hypertonic Saline or Mannitol Treatment in Children With Severe Traumatic Brain Injury.

Importance: Hyperosmolar agents are cornerstone therapies for pediatric severe traumatic brain injury. Guideline recommendations for 3% hypertonic saline (HTS) are based on limited numbers of patients, and no study to date has supported a recommendation for mannitol. Objectives: To characterize current use of hyperosmolar agents in pediatric severe traumatic brain injury and assess whether HTS or mannitol is associated with greater decreases in intracranial pressure (ICP) and/or increases in cerebral perfusion pressure (CPP). Design, Setting, and Participants: In this comparative effectiveness research study, 1018 children were screened and 18 were excluded; 787 children received some form of hyperosmolar therapy during the ICP-directed phase of care, with 521 receiving a bolus. Three of these children were excluded because they had received only bolus administration of both HTS and mannitol in the same hour, leaving 518 children (at 44 clinical sites in 8 countries) for analysis. The study was conducted from February 1, 2014, to September 31, 2017, with follow-up for 1 week after injury. Final analysis was performed July 20, 2021. Interventions: Boluses of HTS and mannitol were administered. Main Outcomes and Measures: Data on ICP and CPP were collected before and after medication administration. Statistical methods included linear mixed models and corrections for potential confounding variables to compare the 2 treatments. Results: A total of 518 children (mean [SD] age, 7.6 [5.4] years; 336 [64.9%] male; 274 [52.9%] White) were included. Participants' mean (SD) Glasgow Coma Scale score was 5.2 (1.8). Bolus HTS was observed to decrease ICP and increase CPP (mean [SD] ICP, 1.03 [6.77] mm Hg; P < .001; mean [SD] CPP, 1.25 [12.47] mm Hg; P < .001), whereas mannitol was observed to increase CPP (mean [SD] CPP, 1.20 [11.43] mm Hg; P = .009). In the primary outcome, HTS was associated with a greater reduction in ICP compared with mannitol (unadjusted ß, -0.85; 95% CI, -1.53 to -0.19), but no association was seen after adjustments (adjusted ß, -0.53; 95% CI, -1.32 to 0.25; P = .18). No differences in CPP were observed. When ICP was greater than 20 mm Hg, greater than 25 mm Hg, or greater than 30 mm Hg, HTS outperformed mannitol for each threshold in observed ICP reduction (>20 mm Hg: unadjusted ß, -2.51; 95% CI, -3.86 to -1.15, P < .001; >25 mm Hg: unadjusted ß, -3.88; 95% CI, -5.69 to -2.06, P < .001; >30 mm Hg: unadjusted ß, -4.07; 95% CI, -6.35 to -1.79, P < .001), with results remaining significant for ICP greater than 25 mm Hg in adjusted analysis. Conclusions and Relevance: In this comparative effectiveness research study, bolus HTS was associated with lower ICP and higher CPP, whereas mannitol was associated only with higher CPP. After adjustment for confounders, both therapies showed no association with ICP and CPP. During ICP crises, HTS was associated with better performance than mannitol.

Reaction Atmospheres and Surface Ligation Control Surface Reactivity and Morphology of Cerium Oxide Nanocrystals during Continuous Addition Synthesis.

Cerium oxide nanocrystals have size- and shape-dependent properties that are potentially useful in a variety of applications if these structural attributes can be controlled through synthesis. Various syntheses have been developed in attempts to access different sizes and shapes, but little is known about selecting reaction conditions to predictably control the growth, and therefore properties, of the nanocrystals. Here, we investigate the role of cerium precursor oxidation states, reaction atmospheres, and acetic acid ligation on the size and shape of cerium oxide nanocrystals. A continuous addition synthesis allowed us to vary individual reaction parameters to better understand how each affects growth and morphology. Under N2, the synthesis leads to either irregular shapes or nanoribbons, whereas the same synthesis under air leads to size-tunable nanocubes. To determine whether air might be oxidizing the cerium precursor and changing its reactivity, we synthesized Ce(IV)-rich and Ce(III) oleate precursors and found that the oxidation state of the precursor has little effect on the resulting nanocrystals. In fact, we found that Ce(IV) oleate is readily reduced to Ce(III) at at temperatures above 100 °C in the reaction medium. The significant role of air during synthesis therefore suggests that oxygen is altering the surface reactivity of the nanocrystals, as opposed to the precursor. We investigated the origin of nanoribbon formation and found that the presence of acetate ligands is responsible for nanoribbon formation in syntheses under N2, with more acetate leading to longer nanoribbons. These insights were used to identify conditions to predictably grow various sizes and shapes of nanocubes and nanoribbons. The findings elucidate the effects that various synthetic parameters can have on cerium oxide nanocrystal synthesis and suggest that redox reactivity may influence growth and properties in other syntheses where changes in the oxidation state occur for the precursor or the nanocrystal surface.