Enhanced Crystallinity of Covalent Organic Frameworks Formed Under Physical Confinement by Exfoliated Graphene.

The polymerization of 1,4-benzenediboronic acid (BDBA) on mica to form a covalent organic framework (COF-1) reveals a dramatic increase in crystallinity when physically confined by exfoliated graphene. COF-1 domains formed under graphene confinement are highly geometric in shape and on the order of square micrometers in size, while outside of the exfoliated flakes, the COF-1 does not exhibit long-range mesoscale structural order, according to atomic force microscopy imaging. Micro-Fourier transform infrared spectroscopy confirms the presence of COF-1 both outside and underneath the exfoliated graphene flakes, and density functional theory calculations predict that higher mobility and self-assembly are not causes of this higher degree of crystallinity for the confined COF-1 domains. The most likely origin of the confined COF-1's substantial increase in crystallinity is from enhanced dynamic covalent crystallization due to the water confined beneath the graphene flake.

Wilderness Medicine Education in the Time of Social Distancing and COVID-19.

Wilderness medicine (WM) education has traditionally been conducted as in-person training. The current COVID-19 pandemic has forced medical schools to cancel clerkships and clinical electives and pivot to remote education. With online media modalities, it is possible to conduct a WM student elective remotely. The use of recorded audio lectures, instructional videos, choice-based simulations, and video conferencing allows students access to nearly all necessary content under the guidance of instructors. Although hands-on practicums are still essential to WM education, the process outlined here enables a temporary alternative during the time of necessary social distancing.

Rebound metabolic acidosis following intentional amygdalin supplement overdose.

Introduction: Amygdalin, marketed misleadingly as supplement "Vitamin B17," is a cyanogenic glycoside. When swallowed, it is hydrolyzed into cyanide in the small intestine, which causes histotoxic hypoxia via inhibition of cytochrome c oxidase. It remains available for purchase online despite a ban from the US Food and Drug Administration. We report a case of massive intentional amygdalin overdose resulting in recurrent cyanide toxicity after initial successful antidotal therapy.Case summary: A 33-year-old woman intentionally ingested 20 g of "apricot POWER B17 Amygdalin" supplements. She presented five hours post-ingestion with vital signs: P 127 bpm, BP 112/65 mmHg, RR 25/min, temperature 98.1 °F, and SpO2 98% RA. She was in agitated delirium, diaphoretic, and mydriatic. Her VBG was notable for a pH of 7.27 (rr 7.32-7.42) and lactate 14.1 mmol/L (rr 0.5-2.2), with ECG demonstrating QTc 538 ms (normal <440 ms). She was empirically treated with hydroxocobalamin and supportive care, but worsened clinically, requiring intubation and additional hydroxocobalamin and sodium thiosulfate, which resolved her toxicity. Twelve hours later, she developed recurrent hypotension, acidemia, and QTc prolongation that resolved with repeat hydroxocobalamin and sodium thiosulfate dosing.Discussion: Our case demonstrates rebound metabolic acidosis after massive amygdalin overdose. Toxicity was associated with prolonged QTc, which warrants further investigation into clinical significance. Redosing of combination antidotal therapy suggested efficacy without adverse effects.

Emergency Medicine Residencies Are Failing Main Street America.

Emergency medicine residencies are commonly based out of large, urban medical centers with very little, if any, exposure to the practice of rural emergency medicine. With one-third of all hospitals and one-fifth of the entire United States population residing in rural areas, more can be done to prepare residents for a career in such a setting. Potential changes include increasing access to rotations at rural sites and altering didactic content and bedside teaching to take into consideration practice with limited access to specialists. In doing so, emergency medicine residents will be better trained and the residents of rural America will be better served.

Myopic Changes in a Climber after Taking Acetazolamide and the Use of Corrective Lenses to Temporize Symptoms: A Case Report from Mount Kilimanjaro.

When performing detailed tasks related to climbing or hiking, accurate vision is important for safety. Acetazolamide is a medication commonly used to prevent acute mountain sickness, but it has an uncommon side effect of transient myopia. Reports of this side effect are mainly associated with its use in obstetrics, where it is often prescribed in higher doses than used in acute mountain sickness prophylaxis. We describe the case of a climber taking low-dose acetazolamide who developed transient myopia. We further describe potential mechanisms of this rare side effect as well as a novel approach of field management utilizing possible materials at hand.

Electron Dynamics and IR Peak Coalescence in Bridged Mixed Valence Dimers Studied by Ultrafast 2D-IR Spectroscopy.

Dynamic IR peak coalescence and simulations based on the optical Bloch equations have been used previously to predict the rates of intramolecular electron transfer in a group of bridged mixed valence dimers of the type [Ru3(O)(OAc)6(CO)L]-BL-[Ru3(O) (OAc)6(CO)L]. However, limitations of the Bloch equations for the analysis of dynamical coalescence in vibrational spectra have been described. We have used ultrafast 2D-IR spectroscopy to investigate the vibrational dynamics of the CO spectator ligands of several dimers in the group. These experiments reveal that no electron site exchange occurs on the time scale required to explain the observed peak coalescence. The high variability in FTIR peak shapes for these mixed valence systems is suggested to be the result of fluctuations in the charge distributions at each metal cluster within a single-well potential energy surface, rather than the previous model of two-site exchange.

Determining equilibrium fluctuations using temperature-dependent 2D-IR.

We demonstrate the capability of temperature-dependent 2D-IR to characterize sources of vibrational population transfer. In a model system of iron diene tricarbonyl "piano stool" complexes, this approach reveals symmetry breaking associated with equilibrium fluctuations and differentiates these from fluxional rearrangement. Tricarbonyl(1,3-butadiene)iron and tricarbonyl(1,5-cyclooctadiene)iron are shown to undergo intramolecular vibrational redistribution (IVR) coupled to the wagging motion of their carbonyl ligands. In the case of both molecules, these equilibrium fluctuations are distinguished from chemical exchange behaviors by their temperature dependence and arguments of molecular symmetry.

Ultrafast observation of a solvent dependent spin state equilibrium in CpCo(CO).

We report the observation of a solvent-dependent spin state equilibrium in the 16-electron photoproduct CpCo(CO). Time-resolved infrared spectroscopy has been used to observe the concurrent formation of two distinct solvated monocarbonyl photoproducts, both of which arise from the same triplet CpCo(CO) precursor. Experiments in different solvent environments, combined with electronic structure theory calculations, allow us to assign the two solvated photoproducts to singlet and triplet CpCo(CO)(solvent) complexes. These results add to our previous picture of triplet reactivity for 16-electron organometallic photoproducts, in which triplets were not believed to interact strongly with solvent molecules. In the case of this photoproduct, it appears that spin crossover does not present a significant barrier to reactivity, and relative thermodynamic stabilities determine the spin state of the CpCo(CO) photoproduct in solution on the picosecond time scale. While the existence of transition metal complexes with two thermally accessible spin states is well-known, this is, to our knowledge, the first observation of a transient photoproduct that exhibits an equilibrium between two stable spin states, and also the first observed case in which a solvent has been able to coordinate as a token ligand to two spin states of the same photoproduct.

Improving the environment for immobilized dehydrogenase enzymes by modifying Nafion with tetraalkylammonium bromides.

Recent research in our group has shown that mixture-casting Nafion with quaternary ammonium bromides can increase the electrochemical flux of redox couples through the membrane and allow for larger redox species to diffuse to the electrode surface. The research has also suggested that when these salts are cast with Nafion micellar pore size is changing. Therefore, it was proposed that the quaternary ammonium salts could be employed to tailor the structure of the Nafion membrane for immobilizing enzymes in the polymer. For cations with a high affinity for the sulfonic acid groups of Nafion, the modified structure of Nafion can also help to stabilize the enzyme and increase activity by providing a protective outer shell and an ideal chemical environment that resists a decrease in pH within the pore structure. This research examines the ability to immobilize dehydrogenase enzymes in Nafion that has been modified with quaternary ammonium bromides. Fluorescence assays, fluorescence microscopy, and cyclic voltammetric studies were employed to analyze the ability to immobilize an enzyme within the membrane, to determine the activity of the immobilized enzyme and to examine the transport of coenzyme within the membrane. Dehydrogenase enzymes immobilized in tetrabutylammonium bromide/Nafion membranes have shown high catalytic activity and enzyme active lifetimes of greater than 45 days. A variety of dehydrogenase enzymes have been successfully immobilized in the membrane, including: alcohol dehydrogenase, aldehyde dehydrogenase, glucose dehydrogenase, and lactic dehydrogenase.