Electrochemical Metal Recycling: Recovery of Palladium from Solution and In Situ Fabrication of Palladium-Carbon Catalysts via Impact Electrochemistry.

Recycling of critical materials, regeneration of waste, and responsible catalyst manufacture have been repeatedly documented as essential for a sustainable future with respect to the environment and energy production. Electrochemical methods have become increasingly recognized as capable of achieving these goals, and "impact" electrochemistry, with the advantages associated with dynamic nanoelectrodes, has recently emerged as a prime candidate for the recovery of metals from solution. In this report, the nanoimpact technique is used to generate carbon-supported palladium catalysts from low-concentration palladium(II) chloride solutions (i.e., a waste stream mimic) as a proof of concept. Subsequently, the catalytic properties of this material in both synthesis (Suzuki coupling reaction) and electrocatalysis (hydrogen evolution) are demonstrated. Transient reductive impact signals are shown and analyzed at potentials negative of +0.4 V (vs SCE) corresponding to the onset of palladium deposition in traditional voltammetry. Direct evidence of Pd modification was obtained through characterization by environmental scanning electron microscopy/energy-dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimetric analysis of impacted particles. This showed the formation of deposits of Pd0 partially covering the 50 nm carbon black particles with approximately 14% Pd (wt %) under the conditions used. This material was then used to demonstrate the conversion of iodobenzene into its biphenyl product (confirmed through nuclear magnetic resonance) and the successful production of hydrogen as an electrocatalyst under acidic conditions (under cyclic voltammetry).

"Janus" Calixarenes: Double-Sided Molecular Linkers for Facile, Multianchor Point, Multifunctional, Surface Modification.

We herein report the synthesis of novel "Janus" calix[4]arenes bearing four "molecular tethering" functional groups on either the upper or lower rims of the calixarene. These enable facile multipoint covalent attachment to electrode surfaces with monolayer coverage. The other rim of the calixarenes bear either four azide or four ethynyl functional groups, which are easily modified by the copper(I)-catalyzed azide-alkyne cycloaddition reaction (CuAAC), either pre- or postsurface modification, enabling these conical, nanocavity reactor sites to be decorated with a wide range of substrates to impart desired chemical properties. Redox active species decorating the peripheral rim are shown to be electrically connected by the calixarene to the electrode surface in either "up" or "down" orientations of the calixarene.

Impact Electrochemistry of MoS2: Electrocatalysis and Hydrogen Generation at Low Overpotentials.

MoS2 materials have been extensively studied as hydrogen evolution reaction (HER) catalysts. In this study nanoparticulate MoS2 is explored as a HER catalyst through impact voltammetry. The onset potential was found to be -0.10 V (vs RHE) at pH 2, which was confirmed to be due to HER by scale-up of the impact experiment to generate and collect a sufficient volume of the gas to enable its identification as hydrogen via gas chromatography. This is in contrast to electrodeposited MoS2, which was found to be stable in pH 2 sulfuric acid solution with an onset potential of -0.29 V (vs RHE), in good agreement with literature. XPS was used to categorize the materials and confirm the chemical composition of both nanoparticles and electrodeposits, with XRD used to analyze the crystal structure of the nanoparticles. The early onset of HER was postulated from kinetic analysis to be due to the presence of nanoplatelets of about 1-3 trilayers participating in the impact reactions, and AFM imaging confirmed the presence of these platelets.

Surface modification of polymeric biomaterials: utilization of cyclodextrins for blood compatibility improvement.

A novel modified polymeric biomaterial surface using cyclodextrins (CDs) for improved blood compatibility was studied. Plasticized poly(vinyl chloride) (PVC-P) was selected for modification and polyethylene was used as a reference material. The modification was achieved by polymer blending. Fibrinogen and albumin adsorption were utilized as indices for the assessment of the blood compatibility. Surface characterization confirmed that CDs were able to accumulate at the PVC surface and alter the surface properties. The combination of other hydrophilic polymers such as poly(ethylene oxide) (PEO) and PEO/poly(propylene oxide) (PPO) copolymers, such as Pluronic F68 (F68), with CDs were also investigated. These modified materials have a remarkable protein-resistant surface. The combination of B-cyclodextrin (B-CD)/PEO and B-CD/F68 in certain feeding ratio are synergistic in producing enhanced blood compatibility.

The in vitro adsorption of cytokines by polymer-pyrolysed carbon.

This study investigated a range of phenol-formaldehyde-aniline-based pyrolysed carbon matrices and their component materials, for their ability to adsorb a range of inflammatory cytokines crucial to the progression of sepsis. The efficiency of adsorption of the target molecules from human plasma was assessed and compared to that of Adsorba 300C, a commercially available cellulose-coated activated charcoal. Results indicate that a number of the primary carbon/resin materials demonstrate efficient adsorption of the cytokines studied here (TNF, IL-6 and IL-8), comparable to other adsorbents under clinical investigation. Our findings also illustrate that these adsorbent capabilities are retained when the primary particles are combined to form a pyrolysed carbon matrix. This capability will enable the engineering of the carbon matrix porosity allowing a blend of carbonised particle combinations to be tailored for maximum adsorption of inflammatory cytokines. The present findings support further investigation of this carbon material as a combined carbon-based filtration/adsorbent device for direct blood purification.

Report of the Task Force on National Fourth Year Medical Student Emergency Medicine Curriculum Guide.

This manuscript reports recommendations of the National Fourth Year Medical Student Emergency Medicine Curriculum Guide Task Force. This task force was convened by 6 major emergency medicine organizations to develop a standardized curriculum for fourth year medical students. The structure of the curriculum is based on clerkship curricula from other specialties such as internal medicine and pediatrics. The report contains a historical context, global and targeted needs assessment, goals and objectives, recommended educational strategies, implementation guidelines, and suggestions on feedback and evaluation.

Novel B(Ar')2(Ar'') hetero-tri(aryl)boranes: a systematic study of Lewis acidity.

A series of homo- and hetero-tri(aryl)boranes incorporating pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl, and pentachlorophenyl groups, four of which are novel species, have been studied as the acidic component of frustrated Lewis pairs for the heterolytic cleavage of H2. Under mild conditions eight of these will cleave H2; the rate of cleavage depending on both the electrophilicity of the borane and the steric bulk around the boron atom. Electrochemical studies allow comparisons of the electrophilicity with spectroscopic measurements of Lewis acidity for different series of boranes. Discrepancies in the correlation between these two types of measurements, combined with structural characterisation of each borane, reveal that the twist of the aryl rings with respect to the boron-centred trigonal plane is significant from both a steric and electronic perspective, and is an important consideration in the design of tri(aryl)boranes as Lewis acids.

Metal-free electrocatalytic hydrogen oxidation using frustrated Lewis pairs and carbon-based Lewis acids.

Whilst hydrogen is a potentially clean fuel for energy storage and utilisation technologies, its conversion to electricity comes at a high energetic cost. This demands the use of rare and expensive precious metal electrocatalysts. Electrochemical-frustrated Lewis pairs offer a metal-free, CO tolerant pathway to the electrocatalysis of hydrogen oxidation. They function by combining the hydrogen-activating ability of frustrated Lewis pairs (FLPs) with electrochemical oxidation of the resultant hydride. Here we present an electrochemical-FLP approach that utilises two different Lewis acids - a carbon-based N-methylacridinium cation that possesses excellent electrochemical attributes, and a borane that exhibits fast hydrogen cleavage kinetics and functions as a "hydride shuttle". This synergistic interaction provides a system that is electrocatalytic with respect to the carbon-based Lewis acid, decreases the required potential for hydrogen oxidation by 1 V, and can be recycled multiple times.

Assessing the in vitro biocompatibility of a novel carbon device for the treatment of sepsis.

The aim of the present study was to conduct a preliminary investigation into the blood biocompatibility of a novel, uncoated carbon for use in a filtration/adsorption device for the treatment of sepsis. Carbon well prototypes were manufactured from phenol-formaldehyde-aniline-based pyrolysed carbons using monolithic polymer technology. Inflammatory blood cell and plasma protein mediation of the inflammatory response were evaluated using the novel carbon prototypes and compared with dialyser membrane and tissue culture plate controls. Assays determining monocyte and granulocyte adhesion, platelet adhesion and activation, granulocyte activation and complement activation were performed. Preliminary findings suggest an adsorptive but passivating carbon surface. Moderate levels of monocyte and granulocytes adhesion were seen in conjunction with adsorption of plasma proteins to the carbon surface. Activation of granulocyte and adherent platelets was not detected and the complement cascade was not activated by the carbons, indicating a surface compatible with blood contact. The results support the further development of the proposed carbon-based device for the treatment of sepsis.

Novel "anchor modification" of polymeric biomaterial surfaces by the utilization of cyclodextrin inclusion complex supramolecules.

In this article, a novel approach for the surface modification of polymeric biomaterials by the utilization of supramolecules was studied. The supramolecules selected were cyclodextrin inclusion complexes (CICs). The biomaterial selected for surface modification was plasticized poly (vinyl chloride) (PVC-P). Results indicate that when the CICs were blended into PVC-P, they tend to migrate and "anchor" on the surface to achieve a remarkable protein-resistant surface, with improved blood compatibility. In comparison with a physical mixture of cyclodextrins and a "guest" molecule, such as poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO and PPO-PEO-PPO for PVC-P modification, CICs modified PVC-P are more consistent in processing and achieve reproducible surface characteristics. Based on this study, a novel "anchor modification" was proposed regarding CICs modified surface. This "anchor modification" is likely to reduce plasticizer extraction from PVC-P and also can be utilized for the modification of polymers other than PVC-P.

Blood interactions with plasticised poly (vinyl chloride): influence of surface modification.

Surface modification of plasticised poly (vinyl chloride) (PVC), with di-(2-ethylhexyl) phthalate (DEHP) as plasticiser, for the improvement of blood compatibility in potential clinical use such as cardiopulmonary bypass was achieved by heparinisation. The influence of surface modification on blood compatibility was assessed in terms of the influence on fibrinogen and factor XII adsorption in vitro, and the generation of thrombin-antithrombin III complex (TAT) and the complement component C3a, in vitro and ex vivo. Electron spectroscopy for chemical analysis (ESCA) was used to characterise the heparinised surface in order to correlate the surface properties with the blood response. Results indicate that at the plasticised PVC surface there is a higher content of heparin than that of the PVC and the DEHP content is lower than that present at the surface of standard plasticised PVC. The blood compatibility assessment confirms the importance of surface modification for the improvement of blood compatibility.