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Surgical aortic valve replacement with a rapid deployment valve (RDV) is a relatively recent treatment option. The aim of this study was to compare the hemodynamic performance of balloon-expandable (BE)-RDVs and BE-transcatheter heart valves (THVs) in a high surgical risk and frail-elderly population.

Multifunctional composites that couple high-capacity adsorbents with catalytic nanoparticles (NPs) offer a promising route toward the degradation of organophosphorus pollutants or chemical warfare agents (CWAs). We couple mesoporous TiO2aerogels with plasmonic Cu nanoparticles (Cu/TiO2) and characterize the degradation of the organophosphorus CWA sarin under both dark and illuminated conditions. Cu/TiO2aerogels combine high dark degradation rates, which are facilitated by hydrolytically active sites at the Cu||TiO2interface, with photoenhanced degradation courtesy of semiconducting TiO2and the surface plasmon resonance (SPR) of the Cu nanoparticles. The TiO2aerogel provides a high surface area for sarin binding (155 m2g–1), while the addition of Cu NPs increases the abundance of hydrolytically active OH sites. Degradation is accelerated on TiO2and Cu/TiO2aerogels with O2. Under broadband illumination, which excites the TiO2bandgap and the Cu SPR, sarin degradation accelerates, and the products are more fully mineralized compared to those of the dark reaction. With O2and broadband illumination, oxidation products are observed on the Cu/TiO2aerogels as the hydrolysis products subsequently oxidize. In contrast, the photodegradation of sarin on TiO2is limited by its slow initial hydrolysis, which limits the subsequent photooxidation. Accelerated hydrolysis occurs on Cu/TiO2aerogels under visible illumination (>480 nm) that excites the Cu SPR but not the TiO2bandgap, confirming that the Cu SPR excitation contributes to the broadband-driven activity. The high hydrolytic activity of the Cu/TiO2aerogels combined with the photoactivity upon TiO2bandgap excitation and Cu SPR excitation is a potent combination of hydrolysis and oxidation that enables the substantial chemical degradation of organophorphorus compounds.

Carbon monoxide (CO) oxidation is not only an important industrial reaction but also a useful model system for investigations into reaction dynamics involving new catalyst designs. In this work, we use CO oxidation to probe the metal−support interactions between Cu nanoparticles and a TiO2aerogel support. We utilized a packed-bed reactor to demonstrate the activity of a Cu/TiO2aerogel catalyst for CO oxidation at temperatures above 463 K. In situinfrared spectroscopic methods revealed that the reaction proceeds primarily by a Cu-assisted Mars-van-Krevelen type mechanism. Results indicate that Ti4+sites are reduced by CO to generate Ti3+sites adjacent to oxygen vacancies. Lattice oxygen extraction appears to be accompanied by interfacial charge transfer from lower work function copper nanoparticles to the TiO2support, as evidenced by variable-temperature infrared spectroscopic studies of adsorbed CO. The charge transfer is evidenced by differences in the nature of CO bound to Ti4+sites within aerogels in the presence and absence of Cu. The Cu particles on the TiO2support lower the vibrational frequency for CO bound to Ti4+sites by 3 cm–1and increase the binding enthalpy by 7 kJ/mol. Infrared spectroscopic probes of oxidation state cycling during catalysis contribute toward the development of an overall CO oxidation reaction mechanism on the Cu/TiO2aerogel.

Protocols that express functional materials in a way that amplifies their surface-to-volume ratio offer a means to probe the structural ambiguity and surface-mediated reactivity of technologically important materials. We previously reported that three-dimensional (3D) ultraporous scaffolds, such as silica aerogels, silica fiber paper, and carbon nanofoam paper (CNF), provide a form factor that expresses energy-storing, catalytic ruthenium oxide (RuOx) as essentially all-surface—and a highly disordered one at that. To track the chemical state and solid-state structure of the 3D-expressed RuOxnanoskins as a function of thermal processing, we use X-ray near-edge structure (XANES), extended X-ray fine structure (EXAFS), and differential pair-distribution function (DPDF) analyses. We find that a Ru-centered ∼2.4 Å correlation present in the as-deposited oxide, also observed in PDF analysis of RuO2·nH2O but previously unassigned, fits the metastable corundum-like Ru2O3structure. This corundum-like feature diminishes in concentration with increasing treatment temperature (25–200 °C), commensurate with an increase in relative rutile RuO2content, electrical conductivity, and charge-storing capacitance of the oxide. Yet disorder persists beyond 8 Å, and a rutile nanocrystalline structure is not attained until >200 °C. The combination of synthetic amplification and total scattering analyses offers a viable approach to elucidate the structural ambiguity of practical, disordered nanomaterials.

Thin-film ruthenium dioxide (RuO2) is a promising alternative material as a conductive electrode in electronic applications because its rutile crystalline form is metallic and highly conductive. Herein, a solution-deposition multilayer technique is employed to fabricate ca. 70 ± 20 nm thick films (nanoskins), and terahertz spectroscopy is used to determine their photoconductive properties. Upon calcining at temperatures ranging from 373 to 773 K, nanoskins undergo a transformation from insulating (localized charge transport) behavior to metallic behavior. Terahertz time-domain spectroscopy (THz-TDS) indicates that nanoskins attain maximum static conductivity when calcined at 673 K (σ = 1030 ± 330 S·cm–1). Picosecond time-resolved terahertz spectroscopy using 400 and 800 nm excitation reveals a transition to metallic behavior when calcined at 523 K. For calcine temperatures less than 523 K, the conductivity increases following photoexcitation (ΔE< 0) while higher calcine temperatures yield films composed of crystalline, rutile RuO2and the conductivity decreases (ΔE> 0) following photoexcitation.

Using a solution-based, non−line-of sight synthesis, we electrolessly deposit ultrathin films of RuO2(“nanoskins”) on planar and 3D substrates and benchmark their activity and stability for oxygen-evolution reaction (OER) in acid electrolyte under device-relevant conditions. When an electrically contiguous ∼9 nm thick RuO2nanoskin is expressed on commercially available, insulating SiO2fiber paper, the RuO2@SiO2electrode exhibits high current density at low overpotential (10 mA cm–2@ η = 280 mV), courtesy of a catalyst amplified in 3D; however, the mass-normalized activity falls short of that achieved for films deposited on planar, metallic substrates (Ti foil). By wrapping the fibers with a <100 nm thick graphitic carbon layer prior to RuO2deposition (RuO2@C@SiO2), we retain the high mass activity of the RuO2(40–60 mA mg–1@ η = 330 mV) and preserve the desirable macroscale properties of the 3D scaffold: porous, lightweight, flexible, and inexpensive. The RuO2@C@SiO2anodes not only achieve the 10 mA cm–2figure of merit at a low overpotential (η = ∼270 mV), but more importantly they do so while (1) minimizing the mass of catalyst needed to achieve this metric, (2) incorporating the catalyst into a practical electrode design, and (3) improving the long-term stability of the catalyst. Our best-performing anodes achieve state-of-the-art or better performance on the basis of area and mass, and do so with a catalyst density 300–580× less than that of bulk RuO2. By limiting the oxidizing potential required to evolve O2at the electrode, even at 10 mA cm–2, we achieve stable activity for 100+ h.

The spectrum of two-dimensional (2D) and layered materials ‘beyond graphene’ offers a remarkable platform to study new phenomena in condensed matter physics. Among these materials, layered hexagonal boron nitride (hBN), with its wide bandgap energy (∼5.0–6.0 eV), has clearly established that 2D nitrides are key to advancing 2D devices. A gap, however, remains between the theoretical prediction of 2D nitrides ‘beyond hBN’ and experimental realization of such structures. Here we demonstrate the synthesis of 2D gallium nitride (GaN) via a migration-enhanced encapsulated growth (MEEG) technique utilizing epitaxial graphene. We theoretically predict and experimentally validate that the atomic structure of 2D GaN grown via MEEG is notably different from reported theory. Moreover, we establish that graphene plays a critical role in stabilizing the direct-bandgap (nearly 5.0 eV), 2D buckled structure. Our results provide a foundation for discovery and stabilization of 2D nitrides that are difficult to prepare via traditional synthesis.

We use intensity-modulated photovoltage spectroscopy (IMVS) and intensity-modulated photocurrent spectroscopy (IMPS) to characterize carrier dynamics in titania (TiO2) aerogels under photocatalytic conditions. By systematically increasing the weight fraction of the sol–gel precursor during TiO2sol–gel synthesis, we are able to impart drastic changes in carrier transport/trapping and improve the photocatalytic activity of TiO2aerogels for two mechanistically divergent photochemical reactions: reductive water splitting (H2generation) and oxidative degradation of dichloroacetate (DCA). The lifetimes of photogenerated electrons increase in going from lowest-to-highest precursor concentrations, as measured by IMVS, indicating increasing site density for electron trapsa trend that correlates with an 8× improvement for photocatalytic H2generation. Electron mobility in the aerogel films, as measured by IMPS, decreases with increasing trap density, further implicating the trapping sites as reactive sites. In contrast, photocatalytic DCA degradationdriven primarily by direct hole transfer to adsorbed DCAdepends only weakly on the electron dynamics in the film. Transient infrared spectroscopy shows no difference in carrier decay among the aerogel samples on picosecond time scales, indicating that changes in carrier dynamics within these networked nanomaterials are only observable at time scales measured by IMPV and IMPS. Correlating hole-mediated and electron-mediated photocatalytic activity with direct measurement of electron dynamics under photocatalytically relevant conditions and time scales comprises a powerful approach to determine how synthetic modifications to networked nanostructured photocatalysts affect the relevant physicochemical phenomena underlying their photocatalytic performance.

Comparison of methanol photochemistry at three-dimensionally (3D) networked aerogels of TiO2or Au–TiO2reveals that incorporated Au nanoparticles strongly sensitize the oxide nanoarchitecture to visible light. Methanol dissociatively adsorbs at the surfaces of TiO2and Au–TiO2aerogels under dark, high-vacuum conditions. Upon irradiation of either ultraporous material with broadband UV light under anaerobic conditions, adsorbed methoxy groups act as hole-traps and extend conduction-band and shallow-trapped electron lifetimes. A higher excited-state electron density arises for UV-irradiated TiO2aerogel relative to commercial nanoparticulate TiO2, indicating that 3D networked TiO2more efficiently separates electron–hole pairs. Upon excitation with narrow-band visible light centered at 550 nm, long-lived excited-state electrons are evident on CH3OH-exposed Au–TiO2aerogelsbut not on identically dosed TiO2aerogelsverifying that incorporated Au nanoparticles sensitize the networked oxide to visible light. Under aerobic conditions (20 Torr O2) and broadband UV illumination, surface-sited formates accumulate as adsorbed methoxy groups oxidize, at similar rates, on Au–TiO2and TiO2aerogels. Moving to excitation wavelengths longer than ∼400 nm (i.e., the low-energy range of UV light) dramatically decreases methoxy photoconversion for methanol-saturated TiO2aerogel, while Au–TiO2aerogel remains highly active for methanol photooxidation. The wavelength dependence of formate production on Au–TiO2tracks the absorbance spectrum for this material, which peaks at λ = 550 nm due to resonance with the surface plasmon in the Au particles. The photooxidation rate for Au–TiO2aerogel at 550 nm is comparable to that for TiO2aerogel under broadband UV illumination, indicating efficient energy transfer from Au to TiO2in the 3D mesoporous nanoarchitecture.

The molecular characterization of a strain of Canine minute virus(CnMV) associated with neonatal death is reported. Three newborn puppies of a litter of Jack Russell terrier dogs died after displaying systemic disease, whereas 2 surviving puppies showed no clinical signs with the exception of transient cardiac abnormalities that were evident by electrocardiography. Necropsy of 1 dead puppy revealed severe lesions in the internal organs. A strain of Canine minute viruswas detected in tissue samples collected from the puppy, and virus circulation was demonstrated by molecular or serological testing in the dam, puppies of the same litter, and other puppies in the same kennel. By sequence and phylogenetic analysis of the gene encoding for the VP2 capsid protein, the strain circulating in the kennel was found to be related to recent Asian CnMV isolates. Continuous molecular surveillance for CnMV in kennels, shelters, and rescue centers would expand the knowledge base on the epidemiological and pathogenetic features of CnMV, which has been known for several decades but still poorly understood.

Abstract

Astroviruses are important pathogens of human beings and animals. Feline astroviruses have been identified by electron microscopy in the feces of either asymptomatic or symptomatic cats, and experimental infection with one isolate was shown to induce enteric clinical signs and virus excretion, thus suggesting a possible role as enteric pathogen. However, due to the lack of specific diagnostic assays, feline astroviruses are not included in the diagnostic algorithms of feline infectious diseases, and their role as feline pathogens remains unclear. The present report describes a dual infection by Feline astrovirusand Feline panleukopenia virusin a 4-month-old cat with severe gastroenteritis and panleukopenia. Upon sequence analysis, the Feline astrovirusstrain was found to be genetically related to astroviruses identified in human beings and felids.

Canine parvovirus (CPV) has been evolving, generating new genetic and antigenic variants throughout the world. This study was conducted to determine the types of CPV circulating in dogs in Figueira da Foz, Portugal. Thirty fecal samples, collected between 2006 and 2007 from dogs with clinical signs of CPV infection, were tested for CPV by a rapid, in-clinic, enzyme-linked immunosorbent assay (ELISA)/immunomigration test, by conventional real-time polymerase chain reaction (PCR), and by minor-groove binding TaqMan PCR. Of the 29 PCR-positive samples, 15 were identified as CPV-2b and 14 as CPV-2c. No CPV-2a was detected. The sensitivity of the ELISA test was 82.76% compared with the PCR assays. No significant associations were found between CPV type, clinical outcome, breed, vaccination status, or age.

ABSTRACTThe antigenic relationships among the original canine parvovirus type 2 (CPV-2) and the variants CPV-2a, -2b, and -2c were evaluated. Cross-antigenic evaluation revealed clear differences among the CPV variants, which were more appreciable by serum neutralization (SN) than by hemagglutination inhibition. Antigenic differences were found mostly between the original CPV-2 and the variants, but they were also observed among the variants CPV-2a, -2b, and -2c. The variant CPV-2c exhibited a unique antigenic pattern, since it was poorly recognized by the sera of animals immunized with CPV-2, CPV-2a, and CPV-2b. However, animals immunized with CPV-2c exhibited higher SN titers to CPV-2b than to the homologous virus CPV-2c. The observed antigenic differences might drive selection of CPV strains by generating differential immune pressure in the canine population, which raises concerns about vaccine efficacy.

Four outbreaks of bovine respiratory disease (BRD) associated with bovine Coronavirus (BCoV) infection in Italian cattle herds were reported. In 3 outbreaks, BRD was observed only in 2–3-month-old feedlot calves, whereas in the remaining outbreak, lactating cows, heifers, and calves were simultaneously affected. By using reverse transcription polymerase chain reaction (RT-PCR), BCoV RNA was detected in all outbreaks without evidence of concurrent viral pathogens (i.e., bovine respiratory syncytial virus, bovine herpesvirus type 1, bovine viral diarrhea virus, bovine parainfluenza virus). Common bacteria of cattle were recovered only from 2 outbreaks of BRD: Staphylococcusspp. and Proteus mirabilis(outbreak 1) and Mannheimia haemolytica(outbreak 4). A recently established real-time RT-PCR assay showed that viral RNA loads in nasal secretions ranged between 3.10 × 102and 7.50 × 107RNA copies/μl of template. Bovine Coronavirus was isolated from respiratory specimens from all outbreaks except outbreak 1, in which real-time RT-PCR found very low viral titers in nasal swabs.

Canine parvovirus (CPV) type 2 (CPV-2) emerged around 1978 as a major pathogen of dogs worldwide. In the mid-1980s, the original CPV-2 had evolved and was completely replaced by 2 variants, CPV-2a and CPV-2b. In 2000, a new variant of CPV (named CPV-2c) was detected in Italy and now cocirculates with types 2a and 2b in that country. The CPV-2c has also been reported from single outbreaks in Vietnam and Spain. This study was conducted to determine if CPV-2c occurs in the United States. Thirty-three fecal samples were collected from dogs in 16 states between April 2006 and April 2007 and were tested for CPV using real-time polymerase chain reaction (PCR). Positive samples were further tested using conventional PCR and minor-groove binding TaqMan PCR assays to determine the viral type and to differentiate vaccine strains from field strains. Twenty-seven samples were positive for CPV, 7 of which were CPV-2c from 5 states: Arizona, California, Georgia, Oklahoma, and Texas. Of the 7 isolates, 4 differed from European CPV-2c isolates by 2 additional single-nucleotide mutations at positions 4076 and 4104, the latter of which produces a ThrAla change at residue 440 located near a major antigenic site. The coast-to-coast geographic distribution of the states in which CPV-2c was detected strongly suggests that this new CPV variant is probably widespread in the United States. The continuous evolution of CPV requires that monoclonal antibody-based and nucleic acid-based diagnostic assays should be periodically checked for sensitivity on prevalent CPV strains.

An outbreak of canine parvovirus type 2 infection caused by the Glu-426 mutant in 2 litters of pups is reported. The infected pups (n= 6) were monitored daily for evidence of clinical signs and hematological changes and for the evaluation of viral shedding in the feces. The disease induced by the Glu-426 mutant was mild in all the infected pups. Vomiting and hemorrhagic diarrhea were not observed; however, the pups developed mucoid diarrhea (3.5 median days), depression (1.5 median days), and relative leukopenia and lymphopenia (2.5 median days). Fever and loss of appetite were observed only in 2 pups. Virus was detected in the feces for 4.5, 6.5, and 46 median days by hemagglutination, virus isolation on cell cultures, and real-time polymerase chain reaction (PCR), respectively. By real-time PCR, the highest viral DNA titers were detected in the feces of both litters at day 10, reaching median values of more than 1010DNA copies/mg of feces.

Nickel-based heterogeneous catalysts are economical alternatives to traditional Pt or Au-based materials, but their specific activity and stability fall short of these precious metals. Many questions remain regarding the active Ni phase for CO oxidation and how the supporting oxide affects its activity and stability under operating conditions. We demonstrate that CeO2aerogel-supported Ni(OH)2nanoparticles (NPs) show superior activity compared to Ni(OH)2NPs supported by commercial, nanometric CeO2powder or TiO2aerogels. Ex situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy reveal that intimate contact between Ni(OH)2NPs and the bonded nanoparticulate CeO2network prevents the conversion to NiO seen with larger aerogel-supported aggregates of Ni(OH)2NPs and unsupported Ni(OH)2NPs. The best stability and activity per mole of Ni is achieved at 2.5 wt % Ni(OH)2on the CeO2aerogel, which converts 95% of CO at 200 °C and maintains activity after 12 h of continuous reaction under dry or humid feedstreams. Computational analysis indicates that CO has far lower adsorption energy on Ni(OH)2compared to NiO, resulting in less poisoning of the active surface sites.