Light-Driven Nitrogen Fixation to Ammonia over Aqueous-Dispersed Mo-Doped TiO2 Colloidal Nanocrystals

Photocatalytic nitrogen fixation to ammonia and nitrates holds great promise as a sustainable route powered by solar energy and fed with renewable energy resources (N2 and H2O). This technology is currently under deep investigation to overcome the limited efficiency of the process. The rational design of efficient and robust photocatalysts is crucial to boost the photocatalytic performance. Widely used bulk materials generally suffer from charge recombination due to poor interfacial charge transfer and difficult surface diffusion. To overcome this limitation, this work explores the use of aqueous-dispersed colloidal semiconductor nanocrystals (NCs) with precise morphological control, better carrier mobility, and stronger redox ability. Here, the TiO2 framework has been modified via aliovalent molybdenum doping, and resulting Mo-TiO2 NCs have been functionalized with charged terminating hydroxyl groups (OH-) for the simultaneous production of ammonia, nitrites, and nitrates via photocatalytic nitrogen reduction in water, which has not been previously found in the literature. Our results demonstrate the positive effect of Mo-doping and nanostructuration on the overall N2 fixation performance. Ammonia production rates are found to be dependent on the Mo-doping loading. 5Mo-TiO2 delivers the highest NH4+ yield rate (ca. 105.3 μmol g-1 L-1 h-1) with an outstanding 90% selectivity, which is almost four times higher than that obtained over bare TiO2. The wide range of advance characterization techniques used in this work reveals that Mo-doping enhances charge-transfer processes and carriers lifetime as a consequence of the creation of new intra band gap states in Mo-doped TiO2 NCs.

Removal of NO at low concentration from air in urban built environments by activated miscanthus biochar

This work presents an innovative and sustainable approach to remove NO emissions from urban ambient air in confined areas (underground parking areas or tunnels) using low-cost activated carbons obtained from Miscanthus biochar (MSP700) by physical activation (with CO₂ or steam) at temperatures ranging from 800 to 900 °C. The NO removal capacity of the activated biochars was evaluated under different conditions (temperature, humidity and oxygen concentration) and compared against a commercial activated carbon. This last material showed a clear dependence on oxygen concentration and temperature, exhibiting a maximum capacity of 72.6% in air at 20 °C, whilst, its capacity notably decreased at higher temperatures, revealing that physical NO adsorption is the limiting step for the commercial sample that presents limited oxygen surface functionalities. In contrast, MSP700-activated biochars reached nearly complete NO removal (99.9%) at all tested temperatures in air ambient. Those MSP700-derived carbons only required low oxygen concentration (4 vol%) in the gas stream to achieve the full NO removal at 20 °C. Moreover, they also showed an excellent performance in the presence of H₂O, reaching NO removal higher than 96%. This remarkable activity results from the abundance of basic oxygenated surface groups, which act as active sites for NO/O₂ adsorption, along with the presence of a homogeneous microporosity of 6 Å, which enables intimate contact between NO and O₂. These features promote the oxidation of NO to NO₂, which is further retained over the carbon surface. Therefore, the activated biochars studied here could be considered promising materials for the efficient removal of NO at low concentrations from air at moderate temperatures, thus closely approaching real-life conditions in confined spaces.

Highly Active and Stable Ni/La-Doped Ceria Material for Catalytic CO2 Reduction by Reverse Water-Gas Shift Reaction

The design of an active, effective, and economically viable catalyst for CO₂ conversion into value-added products is crucial in the fight against global warming and energy demand. We have developed very efficient catalysts for reverse water-gas shift (rWGS) reaction. Specific conditions of the synthesis by combustion allow the obtention of macroporous materials based on nanosized Ni particles supported on a mixed oxide of high purity and crystallinity. Here, we show that Ni/La-doped CeO₂ catalysts─with the "right" Ni and La proportions─have an unprecedented catalytic performance per unit mass of catalyst for the rWGS reaction as the first step toward CO₂ valorization. Correlations between physicochemical properties and catalytic activity, obtained using a combination of different techniques such as X-ray and neutron powder diffraction, Raman spectroscopy, in situ near ambient pressure X-ray photoelectron spectroscopy, electron microscopy, and catalytic testing, point out to optimum values for the Ni loading and the La proportion. Density functional theory calculations of elementary steps of the reaction on model Ni/ceria catalysts aid toward the microscopic understanding of the nature of the active sites. This finding offers a fundamental basis for developing economical catalysts that can be effectively used for CO₂ reduction with hydrogen. A catalyst based on Ni_0.07/(Ce_0.9La_0.1O_x)_0.93 shows a CO production of 58 × 10^-5 mol_CO·g_cat^-1·s^-1 (700 °C, H₂/CO₂ = 2; selectivity to CO > 99.5), being stable for 100 h under continuous reaction.

POS0392 PRESENCE OF FOUR SERUM AUTOANTIBODIES ASSOCIATES WITH THE ACPA STATUS IN EARLY RHEUMATOID ARTHRITIS

Background:

The presence of anti-citrullinated protein antibodies (ACPAs) is a hallmark of rheumatoid arthritis (RA) that precede the development of the disease by years and is used for its clinical diagnosis. However, there are RA subjects that test negative for ACPA and thus the early diagnosis on these patients may be delayed. Furthermore, the presence or absence of ACPA in RA supports the hypothesis that on these two subsets of patients underlie different pathogenesis and clinical outcomes.

Objectives:

In this work, we searched for serum autoantibodies useful to assist the early diagnosis of ACPA-seronegative RA and its management.

Methods:

We profiled the serum autoantibody repertoire of 80 ACPA-seronegative and 80 ACPA-seropositive RA subjects from the Swedish population-based Epidemiological Investigation of RA (EIRA) cohort. A suspension bead array platform built on protein fragments within Human Protein Atlas and selected from an initial untargeted screening using arrays containing 2660 total antigens was employed to identify IgG and IgA serum autoantibodies. A validation phase on antigen suspension bead arrays was carried out on another set of samples from EIRA containing 386 ACPA-seropositive, 358 ACPA-seronegative and 372 randomly selected control subjects of the same age and sex. A sample-specific threshold based on 20 times the median absolute deviation plus the median of all signals was selected to determine the reactivity of samples. The Wilcoxon rank sum test and Fisher’s test were applied for the comparison of autoantibody levels and reactivity frequencies between the groups.

Results:

Our data revealed four antigens associated with the ACPA status (Table 1). Testis-specific Y-encoded-like protein 4 (TSPYL4) showed significantly higher IgG reactivity frequency in ACPA-seronegative subjects compared to ACPA-seropositive (8% vs. 3%; P<0.05). Significant differences at IgG autoantibody levels (P<0.05) were also observed between ACPA-seronegative subjects and controls for this specific antigen. Significantly higher IgG autoantibody levels (P<0.05) towards another antigen, dual specificity mitogen-activated protein kinase kinase 6 (MAP2K6), were also observed in ACPA-seronegative subjects compared to ACPA-seropositive and controls. In contrast, we found significantly higher IgG autoantibody levels (P<0.05) in ACPA-seropositive individuals compared to ACPA-seronegative and controls towards two antigens, anosmin-1 (ANOS-1) and muscle related coiled-coil protein (MURC). ANOS-1 shows also significantly higher IgG reactivity frequency in ACPA-seropositive individuals compared to ACPA-seronegative and controls (22%, 9% and 6% respectively; P<0.05). Interestingly, three out of the four antigens discovered to be associated with the ACPA status in early RA are highly expressed in lungs and heart, two of the main extraarticular sites affected in RA. No significant differences were observed at IgA levels for any of the antigens analyzed.

Table 1.

Scheme of the different phases of the study, the features within each phase and the results. The reactivity to four antigens allows to distinguish ACPA-seronegative (ACPA-), ACPA seropositive (ACPA+) and controls.

PhasesUntargeteddiscoveryTargeteddiscoveryTargetedvalidationNumber of samples80 ACPA-80 ACPA-358 ACPA-372 Controls80 ACPA+80 ACPA+386 ACPA+Antigen arrayplatformPlanararraysSuspensionbead array 1Suspensionbead array 2Number of antigens26606227Number of candidatebiomarkers6227 4 (TSPYL4,MAP2K6,ANOS1,MURC)

Conclusion:

Upon further validation in other early RA sample cohorts, our data suggest the measurement of these four autoantibodies may be useful for the early diagnosis of ACPA-seronegative RA and give insight into the pathogenesis of the different RA subsets.

Characters from table content including title and footnotes:

Disclosure of Interests:

None declared

Antimicrobial resistance and virulence genes profiles of Arcobacter butzleri strains isolated from back yard chickens and retail poultry meat in Chile

This research aims to investigate the presence and pathogenic potential of Arcobacter in poultry meat samples purchased in the retail market of Valdivia (South of Chile) as well as in faecal samples from backyard chickens from rural areas around this city. The isolates obtained were identified by molecular methods. Furthermore, putative virulence genes were assessed by PCR and the antimicrobial resistance was tested by phenotypic methods. Arcobacter was present in 41·6% of the samples, with the highest value in retail poultry meat (55·7%) followed by backyard production (28·0%). Arcobacter butzleri was the most prevalent species (75·6%) followed by Arcobacter skirrowii (14·8%) and Arcobacter cryaerophilus (9·6%). An 8·5% of A. butzleri strains from meat were resistant to both ciprofloxacin and tetracycline and 6·1% were resistant to erythromycin, while none was resistant to gentamycin, unlike strains from domestic chickens, which showed no resistance. Furthermore, A. butzleri strains from chicken meat presented a higher prevalence of virulence genes than strains from domestic chickens. In fact, in this last group, some genes (hecA, hecB and irgA) were completely absent. Therefore, this study provides insight on the epidemiology of Arcobacter in Chilean poultry and suggests that under traditional breeding conditions strains are, apparently, less pathogenic and drug resistant.

Comparison of media and growth conditions for culturing enterohepatic Helicobacter species

This research aims to compare the culturing conditions for enterohepatic Helicobacter, evaluating culture media, incubation atmosphere and susceptibility to antimicrobials used to generate selective conditions. Four common media for the closely related genus Campylobacter (Columbia, Bolton, Brucella and CCDA agar), as well as the need for hydrogen in the microaerobic incubation atmosphere, were evaluated. Serial dilutions of 13 strains belonging to six species (H. apodemus, H. bilis, H. canicola, H. canis, H. equorum and Helicobacter sp.) were inoculated in each media and incubated at 37°C for 48 to 96 h using CampyGen (OXOID) and gaseous exchange (including hydrogen) in parallel. Columbia or Brucella agars were the most appropriate for culturing EHH (P < 0·05). However, there was no significant difference between the atmospheres evaluated (P = 0·13). In addition, minimal inhibitory concentration for six antibiotics showed that all isolates were resistant to trimethoprim, whereas for the rest of the antibiotics (cephalothin, cefoperazone, cefsulodin, teicoplanin and vancomycin) the inhibition range was between 8 and 64 μg ml^{- 1} . Our findings suggest that Columbia or Brucella media, regardless of the use of hydrogen, can be used for the EHH isolation. In addition, the concentration of antibiotics included in commercial campylobacteria supplements is suitable for EHH species recovery. SIGNIFICANCE AND IMPACT OF THE STUDY: Enterohepatic Helicobacter (EHH) infections have been associated with several diseases in humans such as acute gastroenteritis, inflammatory bowel disease and hepatobiliary diseases. Although they are frequently detected in clinical samples by molecular methods, only occasionally they are isolated using culture conditions described for the taxonomic related pathogen Campylobacter sp. This is because the optimal conditions for the isolation of EHH have not yet been described, which results in an underestimation of the prevalence and clinical importance of these emerging pathogens. Therefore, this study provides insight for culturing EHH species.

Recommendations for the follow-up of children with leg length discrepancy: expert consensus

INTRODUCTION

Leg length discrepancy is when the length of one leg is different from the other, and is a common reason for consultation at the pediatrician's and pediatric orthopedist's office. The objective of this study was to develop recommendations for the follow-up, pre-surgical planning, and treatment of children with leg length discrepancy based on expert consensus.

MATERIAL AND METHODS

The Delphi method was used. A coordinating group selected a panel of experts, designed and analyzed each of the rounds of consultations. Semistructured questionnaires were sent by personalized e-mail. Agreement among experts > 80 % was established as the criterion for consensus. At each round of consultation, non-consensual aspects were reformulated and new aspects suggested in the previous round were included. A measure of stability to conclude the consultation was determined when more than 70 % of experts sustained their opinion in successive rounds.

RESULTS

Eight experts in orthopedics and six experts in imaging studies participated. After three rounds of consultations, consensus was reached in terms of 39 recommendations for follow-up, pre-surgical planning, and treatment. These were reorganized into 32 final recommendations.

CONCLUSIONS

These are the first recommendations for the follow-up of children with leg length discrepancy agreed by expert consensus.

Mechanistic View of the Main Current Issues in Photocatalytic CO2 Reduction

After 40 years of research on photocatalytic CO₂ reduction, there are still many unknowns about its mechanistic aspects even for the most common TiO₂-based photocatalytic systems. These uncertainties include the pathways inducing visible-light activity in wide-band gap semiconductors, the charge transfer between semiconductors and plasmonic metal nanoparticles, the unambiguous determination of the origin of C-bearing products, the very first step in the activation of the CO₂ molecule, the factors determining the selectivity, the reasons for photocatalyst deactivation, the closure of the catalytic cycle by the hole-scavenging reagent, and the detailed reaction pathways and the most suitable techniques for their determination. This Perspective discusses these controversial issues based on the most relevant investigations reported so far. For that purpose, we have tried to view the complex CO₂ reduction in a holistic manner, considering today's state-of-the-art approaches, strategies, and techniques for the study of one of the hottest topics in energy research.

Unravelling the effect of charge dynamics at the plasmonic metal/semiconductor interface for CO2 photoreduction

Sunlight plays a critical role in the development of emerging sustainable energy conversion and storage technologies. Light-induced CO2 reduction by artificial photosynthesis is one of the cornerstones to produce renewable fuels and environmentally friendly chemicals. Interface interactions between plasmonic metal nanoparticles and semiconductors exhibit improved photoactivities under a wide range of the solar spectrum. However, the photo-induced charge transfer processes and their influence on photocatalysis with these materials are still under debate, mainly due to the complexity of the involved routes occurring at different timescales. Here, we use a combination of advanced in situ and time-resolved spectroscopies covering different timescales, combined with theoretical calculations, to unravel the overall mechanism of photocatalytic CO2 reduction by Ag/TiO2 catalysts. Our findings provide evidence of the key factors determining the enhancement of photoactivity under ultraviolet and visible irradiation, which have important implications for the design of solar energy conversion materials.

Gas Phase Hydrogenation of Furaldehydes via Coupling with Alcohol Dehydrogenation over Ceria Supported Au-Cu

We have investigated the synthesis and application of Au-Cu/CeO₂ (Cu: Au = 2) in the continuous gas phase (P = 1 atm; T = 498 K) coupled hydrogenation of 5-hydroxymethyl-2-furaldehyde (HMF) with 2-butanol dehydrogenation. STEM-EDX analysis revealed a close surface proximity of both metals in Au-Cu/CeO₂ post-TPR. XPS measurements suggest (support → metal) charge transfer to form Auδ- and strong metal-support interactions to generate Cu⁰ and Cu⁺. Au-Cu/CeO₂ promoted the sole formation of 2,5-dihydroxymethylfuran (DHMF) and 2-butanone in the HMF/2-butanol coupling with full hydrogen utilisation. Under the same reaction conditions, Au/CeO₂ was fully selective to DHMF in standard HMF hydrogenation (using an external hydrogen supply), but delivered a lower production rate and utilised less than 0.2% of the hydrogen supplied. Exclusive -C=O hydrogenation and -OH dehydrogenation is also demonstrated for the coupling of a series of m-substituted (-CH₃, -CH₂CH₃, -CH₂OH, -CF₃, -N(CH₃)₂, -H) furaldehydes with alcohol (1-propanol, 1-butanol, 2-propanol, 2-butanol, cyclohexanol) dehydrogenation over Au-Cu/CeO₂, consistent with a nucleophilic mechanism. In each case, we observed a greater hydrogenation rate and hydrogen utilisation efficiency with a 3⁻15 times lower E-factor in the coupling process relative to standard hydrogenation. Our results demonstrate the feasibility of using hydrogen generated in situ through alcohol dehydrogenation for the selective hydrogenation of m-furaldehydes with important industrial applications.

Role of Support Oxygen Vacancies in the Gas Phase Hydrogenation of Furfural over Gold

Abstract

We have examined the role of support oxygen vacancies in the gas phase hydrogenation of furfural over Au/TiO₂ and Au/CeO₂ prepared by deposition–precipitation. Both catalysts exhibited a similar Au particle size distribution (1–6 nm) and mean (2.8–3.2 nm). Excess H₂ consumption during TPR is indicative of partial support reduction, which was confirmed by O₂ titration. Gold on CeO₂ with a higher redox potential exhibited a greater oxygen vacancy density. A lower furfural turnover frequency (TOF) was recorded over Au/CeO₂ than Au/TiO₂ and is linked to suppressed H₂ chemisorption capacity and strong –C=O interaction at oxygen vacancies that inhibited activity. Gold on non-reducible Al₂O₃ as benchmark exhibited greater H₂ uptake and delivered the highest furfural TOF. Full selectivity to the target furfuryl alcohol was achieved over Au/TiO₂ and Au/Al₂O₃ at 413 K and over Au/CeO₂ at 473 K with hydrogenolysis to 2-methylfuran at higher reaction temperature (523 K). A surface reaction mechanism is proposed to account for the activity/selectivity response.

Graphical Abstract

'Arcobacter porcinus' sp. nov., a novel Arcobacter species uncovered by Arcobacter thereius

Arcobacter thereius is a species associated with human disease. A group of A. thereius pork strains (represented by strain LMG 24487) clustered separately from the type strain (LMG 24486^T) in the 16S rRNA and multilocus phylogenetic trees. In silico DNA-DNA hybridization and average nucleotide identity results between their genomes (93.3 and 51.1%) confirmed ‘Arcobacter porcinus’ (LMG 24487^T) as a new species.

Genotypic and phenotypic diversity in Enterococcus faecalis: is agar invasion a pathogenicity score?

OBJECTIVES

The main objective of the present study is to analyze different genotypic and phenotypic traits related to virulence in Enterococcus faecalis, as well as evaluated the agar invasion phenotype in a collection of isolates with different clinical origins.

MATERIAL AND METHODS

Seventy-nine E. faecalis isolates, with invasive and non-invasive clinical origins, have been used in this work. Presence of cytolysin activator (cylA), gelatinase (gelE), surface protein (esp), aggregation substance (asa1), endocarditis antigen (efaA), and collagen-binding protein (ace) have been analyzed by PCR. Phenotypic characterization included gelatinase activity, haemolysin production, biofilm formation and agar invasion.

RESULTS

All the isolates tested harboured at least one of the virulence determinants. The 95.5% of isolates from haematologic samples were positive for agar invasion test, significantly higher than isolates from non-invasive diseases. A significant reduction in relative invasion area was observed in three selected agar-invasive strains after 15 serial passages.

CONCLUSIONS

It has been observed a significant high prevalence of agar-invasion positive isolates among strains belonged to haematological samples. Agar invasiveness is reduced after adaptation of clinical isolates to laboratory conditions, showing that agar invasion phenotype can be modulate by culture conditions as other virulence factors observed in different bacterial species.

Composition and organization of the SCZ: a large germinal layer containing neural stem cells in the adult mammalian brain

Two known germinal zones continue to generate new neurons and glia in the adult mammalian brain: the subventricular zone (SVZ), lining the lateral walls of the lateral ventricle, and the subgranular zone of the dentate gyrus. Here we describe a region we will refer to as the subcallosal zone (SCZ). The SCZ is a caudal extension of the SVZ that is no longer associated to an open ventricle. It lies between the hippocampus and the corpus callosum. Cells isolated from the SCZ and cultured as neurospheres behave as neural stem cells in vitro. Using electron and light microscopy, we describe the cell types present in this region and how their organization differs from that of the SVZ. Using retroviral labeling and homotypic-homochronic microtransplantation techniques, we show that the majority of cells born in the SCZ migrate into the corpus callosum to become oligodendrocytes in vivo. This study defines the organization and fate of cells born in a large germinal region of the adult forebrain.