Organometallic iridium complexes have been reported as water oxidation catalysts (WOCs) in the presence of ceric ammonium nitrate (CAN). One challenge for all WOCs regardless of the metal used is stability. Here we provide evidence for extensive modification of many Ir-based WOCs even after exposure to only 5 or 15 equiv of Ce(IV) (whereas typically 100-10000 equiv are employed during WOC testing). We also show formation of Ir-rich nanoparticles (likely IrO(x)) even in the first 20 min of reaction, associated with a Ce matrix. A combination of UV-vis and NMR spectroscopy, scanning transmission electron microscopy, and powder X-ray diffraction is used. Even simple IrCl(3) is an excellent catalyst. Our results point to the pitfalls of studying Ir WOCs using CAN.
Important requirements for exogenous
dyes or contrast agents in
magnetic resonance imaging (MRI) include an effective concentration
of paramagnetic or superparamagnetic ions at the target to be imaged.
We report the concise synthesis and characterization of several new
enantiopure bifunctional derivatives of (α1R,α4R,α7R,α10R)-α1,α4,α7,α10-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid (DOTMA) (and their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic
acid (DOTA) analogues as controls) that can be covalently attached
to a contrast agent delivery system using either click or peptide
coupling chemistry. Gd complexes of these derivatives can be attached
to delivery systems while maintaining optimal water residence time
for increased molecular imaging sensitivity. Long chain biotin (LC-biotin)
derivatives of the Eu(III) and Gd(III) chelates associated with avidin
are used to demonstrate higher efficiencies. Variable-temperature
relaxometry, 17O NMR, and nuclear magnetic resonance dispersion
(NMRD) spectroscopy used on the complexes and biotin–avidin
adducts measure the influence of water residence time and rotational
correlation time on constrained and unconstrained systems. The Gd(III)-DOTMA
derivative has a shorter water residence time than the Gd(III)-DOTA
derivative. Compared to the constrained Gd(III)-DOTA derivatives,
the rotationally constrained Gd(III)-DOTMA derivative has ∼40%
higher relaxivity at 37 °C, which could increase its sensitivity
as an MRI agent as well as reduce the dose of the targeting agent.
A 52-year-old type 2 diabetic man previously on canagliflozin developed severe anion gap metabolic acidosis and markedly elevated beta-hydroxybutyrate on postoperative day (POD) 2 status post laparoscopic Roux-en-Y gastric bypass. An insulin drip and aggressive intravenous fluid repletion were initiated, and electrolytes were monitored and repleted. His anion gap closed, and he was discharged on POD 4. This euglycaemic diabetic ketoacidosis prolonged his hospital stay by 2 days.
Malignant pleural effusions are common complications in patients with primary or metastatic cancer to the lungs. In this article, we describe a unique case of a patient with history of diffuse pulmonary metastases from gallbladder adenocarcinoma who acutely developed a bilious pleural effusion following endoscopic retrograde cholangiopancreatography. We believe the bilious pleural effusion (cholethorax or bilothorax) developed as a complication of endoscopic retrograde cholangiopancreatography rather than tumor burden causing a fistula from the biliary tree to the right pleural space. We discuss possible mechanisms of formation of the bilious pleural effusion in our patient and present a literature review of previously reported cases of bilious pleural effusions.
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