Nitrogen Reduction Testing with Real-Time NH Yield Quantification Using Orbital Multiturn Time-of-Flight Mass Spectrometry.

Yield validation of dinitrogen reduction reaction (NRR) catalysts with N isotope labeling experiments is frustrated by the high cost of N and the frequent occurrence of NH and NO impurities in commercial N sources. Also, gas diffusion electrode (GDE) cell architectures are relevant to scaling NRR but underexplored and limited by ex situ product analysis methods. To overcome these obstacles, we develop and demonstrate a protocol for NRR catalyst testing using a scalable GDE cell architecture and specialized test station that facilitates in-line product analysis with multiturn time-of-flight mass spectrometry.

Membranes Matter: Preventing Ammonia Crossover during Electrochemical Ammonia Synthesis.

The electrochemical nitrogen and nitrate reduction reactions (E-NRR and E-NORR) promise to provide decentralized and fossil-fuel-free ammonia synthesis, and as a result, E-NRR and E-NORR research has surged in recent years. Membrane NH/NH crossover during E-NRR and E-NORR decreases Faradaic efficiency and thus the overall yield. During catalyst evaluation, such unaccounted-for crossover results in measurement error.

Integrated halide perovskite photoelectrochemical cells with solar-driven water-splitting efficiency of 20.8.

Achieving high solar-to-hydrogen (STH) efficiency concomitant with long-term durability using low-cost, scalable photo-absorbers is a long-standing challenge. Here we report the design and fabrication of a conductive adhesive-barrier (CAB) that translates >99% of photoelectric power to chemical reactions. The CAB enables halide perovskite-based photoelectrochemical cells with two different architectures that exhibit record STH efficiencies.

Failure Modes of Platinized pn-GaInP Photocathodes for Solar-Driven H Evolution.

The long-term stability for the hydrogen-evolution reaction (HER) of homojunction pn-GaInP photocathodes (band gap = 1.8 eV) with an electrodeposited Pt catalyst (pn-GaInP/Pt) has been systematically evaluated in both acidic and alkaline electrolytes. Electrode dissolution during chronoamperometry was correlated with changes over time in the current density-potential (-) behavior to reveal the underlying failure mechanism.

Engineering Surface Architectures for Improved Durability in III-V Photocathodes.

GaInP has shown promise as the wide bandgap top junction in tandem absorber photoelectrochemical (PEC) water splitting devices. Among previously reported dual-junction PEC devices with a GaInP top cell, those with the highest performance incorporate an AlInP window layer (WL) to reduce surface recombination and a thin GaInP capping layer (CL) to protect the WL from corrosion in electrolytes. However, the stability of these III-V systems is limited, and durability continues to be a major challenge broadly in the field of PEC water splitting.

Understanding the Stability of Etched or Platinized p-GaInP Photocathodes for Solar-Driven H Evolution.

The long-term stability in acidic or alkaline aqueous electrolytes of p-GaInP photocathodes, with a band gap of ∼1.8 eV, for the solar-driven hydrogen-evolution reaction (HER) has been evaluated from a thermodynamic, kinetic, and mechanistic perspective. At either pH 0 or pH 14, etched p-GaInP electrodes corroded cathodically under illumination and formed metallic In on the photoelectrode surface.

High performance III-V photoelectrodes for solar water splitting via synergistically tailored structure and stoichiometry.

Catalytic interface of semiconductor photoelectrodes is critical for high-performance photoelectrochemical solar water splitting because of its multiple roles in light absorption, electrocatalysis, and corrosion protection. Nevertheless, simultaneously optimizing each of these processes represents a materials conundrum owing to conflicting requirements of materials attributes at the electrode surface. Here we show an approach that can circumvent these challenges by collaboratively exploiting corrosion-resistant surface stoichiometry and structurally-tailored reactive interface.

Protection of GaInP Photocathodes by Direct Photoelectrodeposition of MoS Thin Films.

Catalytic MoS thin films have been directly photoelectrodeposited on GaInP photocathodes for stable photoelectrochemical hydrogen generation. Specifically, the MoS deposition conditions were controlled to obtain 8-10 nm films directly on p-GaInP substrates without ancillary protective layers. The films were nominally composed of MoS, with additional MoOS and MoO species detected and showed no long-range crystalline order.

Covalent Surface Modification of Gallium Arsenide Photocathodes for Water Splitting in Highly Acidic Electrolyte.

Efficient water splitting using light as the only energy input requires stable semiconductor electrodes with favorable energetics for the water-oxidation and proton-reduction reactions. Strategies to tune electrode potentials using molecular dipoles adsorbed to the semiconductor surface have been pursued for decades but are often based on weak interactions and quickly react to desorb the molecule under conditions relevant to sustained photoelectrolysis. Here, we show that covalent attachment of fluorinated, aromatic molecules to p-GaAs(1 0 0) surfaces can be employed to tune the photocurrent onset potentials of p-GaAs(1 0 0) photocathodes and reduce the external energy required for water splitting.

Molybdenum Disulfide as a Protection Layer and Catalyst for Gallium Indium Phosphide Solar Water Splitting Photocathodes.

Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis because MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, and light-limited current density) after 60 h of operation.

Water reduction by a p-GaInP2 photoelectrode stabilized by an amorphous TiO2 coating and a molecular cobalt catalyst.

Producing hydrogen through solar water splitting requires the coverage of large land areas. Abundant metal-based molecular catalysts offer scalability, but only if they match noble metal activities. We report on a highly active p-GaInP2 photocathode protected through a 35-nm TiO2 layer functionalized by a cobaloxime molecular catalyst (GaInP2-TiO2-cobaloxime).

Semiconductor interfacial carrier dynamics via photoinduced electric fields.

Solar photoconversion in semiconductors is driven by charge separation at the interface of the semiconductor and contacting layers. Here we demonstrate that time-resolved photoinduced reflectance from a semiconductor captures interfacial carrier dynamics. We applied this transient photoreflectance method to study charge transfer at p-type gallium-indium phosphide (p-GaInP2) interfaces critically important to solar-driven water splitting.

Understanding the ligamentum teres of the hip: a histological study.

Objective: To perform a histological study describing the microstructure of the ligamentum teres of the hip, with special emphasis on the presence of nerve bundles. Our study aims to correlate the microstructure of the ligamentum teres with its postulated functions, allowing greater understanding of its role within the hip joint.

Methods: Fresh specimens excised intra-operatively in 11 patients undergoing open hip procedures were preserved in formalin and sent to the laboratory for histological analysis by our collaborating pathologist.

Phosphonic Acid Modification of GaInP2 Photocathodes Toward Unbiased Photoelectrochemical Water Splitting.

The p-type semiconductor GaInP2 has a nearly ideal bandgap (∼1.83 eV) for hydrogen fuel generation by photoelectrochemical water splitting but is unable to drive this reaction because of misalignment of the semiconductor band edges with the water redox half reactions. Here, we show that attachment of an appropriate conjugated phosphonic acid to the GaInP2 electrode surface improves the band edge alignment, closer to the desired overlap with the water redox potentials.

Langerhans cell histiocytosis: a comprehensive review.

Langerhans cell histiocytosis (LCH) is currently regarded as a myeloid neoplasm, with remarkably broad clinical spectrum, ranging from isolated skin or bone lesions to a disseminated disease that can involve nearly any organ. LCH is generally regarded as a sporadic disease that occurs predominantly in the paediatric population. The diagnosis of LCH is confirmed by immunohistochemistry (IHC) by demonstrating the presence of dendritic cell markers such as S100 protein, in addition to CD1a and langerin.

CD14 deficiency impacts glucose homeostasis in mice through altered adrenal tone.

The toll-like receptors comprise one of the most conserved components of the innate immune system, signaling the presence of molecules of microbial origin. It has been proposed that signaling through TLR4, which requires CD14 to recognize bacterial lipopolysaccharide (LPS), may generate low-grade inflammation and thereby affect insulin sensitivity and glucose metabolism. To examine the long-term influence of partial innate immune signaling disruption on glucose homeostasis, we analyzed knockout mice deficient in CD14 backcrossed into the diabetes-prone C57BL6 background at 6 or 12 months of age.

Psychiatric considerations in patients with decreased levels of consciousness.

When patients present to the emergency department with changes in behavior and levels of consciousness, psychiatric causes often move to the top of the list of diagnostic considerations. It is important to thoroughly assess such patients for medical causes. Although it is not common for primary psychiatric conditions to present with altered levels of consciousness, severe cases may present in this fashion.

The successful use of right unilateral ultra-brief pulse electroconvulsive therapy in an adolescent with catatonia.

Right unilateral ultra-brief electroconvulsive therapy (RUL UB ECT) has been shown to be efficacious with minimal cognitive adverse effects in adult patients with major depression. We present the case of a 14-year-old girl with major depressive disorder with catatonic and psychotic features whose symptoms remitted after 12 treatments of RUL UB ECT.

Metformin inhibits proinflammatory responses and nuclear factor-kappaB in human vascular wall cells.

Objective: Metformin may benefit the macrovascular complications of diabetes independently of its conventional hypoglycemic effects. Accumulating evidence suggests that inflammatory processes participate in type 2 diabetes and its atherothrombotic manifestations. Therefore, this study examined the potential action of metformin as an inhibitor of pro-inflammatory responses in human vascular smooth muscle cells (SMCs), macrophages (Mphis), and endothelial cells (ECs).

Cytokines in the pathogenesis of atherosclerosis.

Research during the last two decades established atheromatous lesions as active sites of inflammation and immune responses, contrasting to the traditional view of atherosclerosis as an acellular lesion composed of lipid deposits. In particular, cytokines appear to orchestrate the chronic development of atherosclerosis, eventually leading to the formation of complex atherosclerotic plaques, which can trigger acute thromboembolic complications, such as myocardial infarction or stroke. Indeed the rupture-prone plaque, characterized by a thin fibrous cap overlaying a voluminous lipid core, exhibits accumulation of various pro-inflammatory cytokines.

Expression of interleukin (IL)-18 and functional IL-18 receptor on human vascular endothelial cells, smooth muscle cells, and macrophages: implications for atherogenesis.

Although considerable evidence implicates the cytokine interferon (IFN)-gamma in atherogenesis, the proximal inducers and the range of sources of its expression remain unknown. This study tested the hypothesis that interleukin (IL)-18 regulates IFN-gamma expression during atherogenesis. Indeed, human atheroma in situ expressed IL-18 and elevated levels of its receptor subunits, IL-18Ralpha/beta, compared with nondiseased arterial tissue.