Tracking Active Phase Behavior on Boron Nitride during the Oxidative Dehydrogenation of Propane Using Operando X-ray Raman Spectroscopy.

Hexagonal boron nitride (hBN) is a highly selective catalyst for the oxidative dehydrogenation of propane (ODHP) to propylene. Using a variety of ex situ characterization techniques, the activity of the catalyst has been attributed to the formation of an amorphous boron oxyhydroxide surface layer. The ODHP reaction mechanism proceeds via a combination of surface mediated and gas phase propagated radical reactions with the relative importance of both depending on the surface-to-void-volume ratio. Here we demonstrate the unique capability of operando X-ray Raman spectroscopy (XRS) to investigate the oxyfunctionalization of the catalyst under reaction conditions (1 mm outer diameter reactor, 500 to 550 °C, P = 30 kPa C3H8, 15 kPa O2, 56 kPa He). We probe the effect of a water cofeed on the surface of the activated catalyst and find that water removes boron oxyhydroxide from the surface, resulting in a lower reaction rate when the surface reaction dominates and an enhanced reaction rate when the gas phase contribution dominates. Computational description of the surface transformations at an atomic-level combined with high precision XRS spectra simulations with the OCEAN code rationalize the experimental observations. This work establishes XRS as a powerful technique for the investigation of light element-containing catalysts under working conditions.

Fluorescence microscope light source stability.

The process of fluorescence starts with the efficient generation of light that is required for the excitation of fluorophores. As such, light sources are a crucial component of a fluorescence microscope. Choosing the right illumination tool can not only improve the quality of experimental results, but also the microscope's economic and environmental footprint. While arc lamps have historically proven to be a reliable light source for widefield fluorescence microscopy, solid-state light-emitting diodes (LEDs) have become the light source of choice for new fluorescence microscopy systems. In this paper, we demonstrate that LEDs have superior light stability on all timescales tested and use less electrical power than traditional light sources when used at lower power outputs. They can be readily switched on and off electronically, have a longer lifetime and they do not contain mercury, and thus are better for the environment. We demonstrate that it is important to measure light source power output during warm-up and switching, as a light source's responsiveness (in terms of power) can be quite variable. Several general protocols for testing light source stability are presented. A detailed life cycle analysis shows that an LED light source can have a fourfold lower environmental impact when compared to a metal halide source.

Malignant cerebral edema after cranioplasty, a rare complication: case series and literature review.

Cranioplasty is standard neurosurgery performed after decompressive craniectomy. Fatal malignant cerebral oedema complications associated with this procedure are rare and clinically distinct, although unpredictable. It is thought that the pressure difference from removing atmospheric pressure had a long-term effect on the brain. This combined with the negative pressure applied by intraoperative pressure drainage may impact the perfusion brain. Here, the authors report four cases of cerebral oedema after cranioplasty and review similar cases in the literature. Case presentation: The authors report on four cases of patients who underwent cranioplasty following decompressive craniotomy and subsequently died after surgery. Three of the patients had undergone craniotomy following trauma, while one patient had skull resorption. All four patients developed cerebral oedema immediately after surgery and exhibited significant craniofacial depression (also known as sunk flap syndrome). A negative pressure drainage system was utilized in all cases. One patient remained intubated, while the remaining three developed postoperative epilepsy and subsequently fell into a coma. Dilated and fixed pupils were observed in all patients, and computed tomography scans revealed diffuse cerebral oedema. Despite intensive resuscitation efforts and attempts at decompression, all four patients ultimately succumbed to their conditions. Conclusion: Fatal post-cranioplasty malignant cerebral oedema is a rare but very dangerous complication. Despite being rare, neurosurgeons should be aware that this fatal complication can occur after cranioplasty.

Novel inhibitory function of miR-125b in melanogenesis.

MicroRNAs are known to be the important regulators of skin physiology and considered as new therapeutic targets to treat skin diseases. In this study, miR-125b was identified as a potent regulator of steady-state melanogenesis. We found that the expression of miR-125b was inversely related to pigment levels. A miR-125b mimic decreased the expression of pigmentation-related gene and melanin content, implying that miR-125b functions to decrease pigmentation. Moreover, we observed that the reduction in miR-125b expression in pigmented cells was at least partially due to the hypermethylation of the MIR125B-1 promoter, and miR-125b expression was regulated by intracellular cAMP levels.