Cefazolin-induced hypoprothrombinemia.

Long-term antibiotic use can be associated with a myriad of side effects, ranging from relatively benign to life-threatening. The most common side effects of cephalosporins include dermatologic reactions and diarrhea. Here, we present a rarer side effect: a spontaneous retroperitoneal hematoma in the setting of cefazolin administration for vertebral osteomyelitis. Several cephalosporins have been implicated in coagulopathy secondary to hypoprothrombinemia. However, only a few case reports have implicated cefazolin, and all have occurred in the context of acute or chronic renal failure. Our case of cefazolin-induced coagulopathy occurred in a patient with normal renal function.

Controlling the 3-D morphology of Ni-Fe-based nanocatalysts for the oxygen evolution reaction.

Controlling the 3-D morphology of nanocatalysts is one of the underexplored but important approaches for improving the sluggish kinetics of the oxygen evolution reaction (OER) in water electrolysis. This work reports a scalable, oil-based method based on thermal decomposition of organometallic complexes to yield highly uniform Ni-Fe-based nanocatalysts with a well-defined morphology (i.e. Ni-Fe core-shell, Ni/Fe alloy, and Fe-Ni core-shell). Transmission electron microscopy reveals their morphology and composition to be NiOx-FeOx/NiOx core-mixed shell, NiOx/FeOx alloy, and FeOx-NiOx core-shell. X-ray techniques resolve the electronic structures of the bulk and are supported by electron energy loss spectroscopy analysis of individual nanoparticles. These results suggest that the crystal structure of Ni is most likely to contain α-Ni(OH)2 and that the chemical environment of Fe is variable, depending on the morphology of the nanoparticle. The Ni diffusion from the amorphous Ni-based core to the iron oxide shell makes the NiOx-NiOx/FeOx core-mixed shell structure the most active and the most stable nanocatalyst, which outperforms the comparison NiOx/FeOx alloy nanoparticles expected to be active for the OER. This study suggests that the chemical environment of the mixed NiOx/FeOx alloy composition is important to achieve high electrocatalytic activity for the OER and that the 3-D morphology plays a key role in the optimization of the electrocatalytic activity and stability of the nanocatalyst for the OER.

Rapid Deposition of Uniform Polydopamine Coatings on Nanoparticle Surfaces with Controllable Thickness.

Polydopamine is a bioinspired, versatile material that can adhere to bulk and nanoscale surfaces made of disparate materials to improve their physical and chemical properties in many applications. The typical methods to coat polydopamine on the nanoparticle substrates usually take several hours to a day. This work successfully applies a dispersion method to form a controllable, uniform coating on a nanoparticle surface within minutes. Using plasmonic Ag nanoparticles as a substrate, the coating thickness can be monitored using a spectroscopic method based on the extinction peak shifts of the Ag nanoparticles. The deposition rate increases with dopamine concentration; however, too much excess dopamine leads to the formation of free dopamine particles. The optimized concentration of dopamine (i.e., ∼6 mM) can be applied to other nanoparticles by normalizing the number of particles to maintain a constant concentration of dopamine per unit surface area (i.e., 1.70 × 104 dopamine/nm2). The molecular dynamics simulation reveals that the amount of hydrogen bonding increases with water content, suggesting that sufficient mixing using the dispersion tool facilitates the formation of hydrogen bonding, thus rapidly depositing PDA on the nanoparticle surface. The physical and chemical properties (e.g., pH response and thermal stability) can be tailored by varying the coating thickness due to the changes in the number of hydrogen bonds and the conformation of π-π interactions. This dispersion method provides a facile means to control the PDA coating thickness on nanoparticle surfaces and thus the surface properties of nanoparticles toward various applications.

Water adsorption on clay minerals as a function of relative humidity: application of BET and Freundlich adsorption models.

Water adsorption on kaolinite, illite, and montmorillonite clays was studied as a function of relative humidity (RH) at room temperature (298 K) using horizontal attenuated total reflectance (HATR) Fourier transform infrared (FTIR) spectroscopy equipped with a flow cell. The water content as a function of RH was modeled using the Brunauer, Emmett, and Teller (BET) and Freundlich adsorption isotherm models to provide complementary multilayer adsorption analysis of water uptake on the clays. A detailed analysis of model fit integrity is reported. From the BET fit to the experimental data, the water content on each of the three clays at monolayer (ML) water coverage was determined and found to agree with previously reported gravimetric data. However, BET analysis failed to adequately describe adsorption phenomena at RH values greater than 80%, 50%, and 70% RH for kaolinite, illite, and montmorillonite clays, respectively. The Freundlich adsorption model was found to fit the data well over the entire range of RH values studied and revealed two distinct water adsorption regimes. Data obtained from the Freundlich model showed that montmorillonite has the highest water adsorption strength and highest adsorption capacity at RH values greater than 19% (i.e., above ML water adsorption) relative to the kaolinite and illite clays. The difference in the observed water adsorption behavior between the three clays was attributed to different water uptake mechanisms based on a distribution of available adsorption sites. It is suggested that different properties drive water adsorption under different adsorption regimes resulting in the broad variability of water uptake mechanisms.