Doping Effects on the Performance of Paired Metal Catalysts for the Hydrogen Evolution Reaction

Metal heteroatoms dispersed in nitrogen-doped graphene display promising catalytic activity for fuel cell reactions such as the hydrogen evolution reaction (HER). Here we explore the effects of dopant concentration on the synergistic catalytic behaviour of a paired metal atom active site comprised of Co and Pt atoms. The metals are coordinated to six atoms in a vacancy of N-doped graphene. We find that HER activity is enhanced with increasing N concentration, where the free energy of hydrogen atom adsorption ranges from 0.23 to -0.42 eV as the doping changes from a single N atom doped in the pore, to fully doped coordination sites. The results indicated that the effect of N is to make the Co atom more active towards H adsorption and presents a means through which transition metals can be modified to make more effective and sustainable fuel cell catalysts

Evaluating the catalytic efficiency of paired, single-atom catalysts for the oxygen reduction reaction

Paired, single-atom catalysts have been shown to demonstrate synergistic effects computationally and experimentally which enable them to outperform the benchmark catalyst, Pt/C, for electrochemical reactions. We explore the limit of these catalysts by screening different transition metal atoms (M = Co, Pt, Fe, Ni) in nitrogen-doped graphene for their ability to catalyze the oxygen reduction reaction (ORR). We employ density functional theory methods to explore the electronic factors affecting catalytic activity in an effort to rationalize trends in the performance of materials which are promising candidates for the next generation of electrocatalysts. It is found that CoPt@N8V4, composed of paired Co and Pt in a nitrogen-doped four-atom vacancy in graphene (N8V4), performs ideally for the ORR with an overpotential (η) of 0.30 V, followed closely by Co and Ni (η = 0.35 V) and paired Co (η = 0.37 V). The origin of activity is suggested to be the changing reduction potential of the active Co atom via the local distortion of the pore by the spectating metal partner. We utilize the ORR scaling relations and plot catalytic activity on a volcano plot, which we correlate with the degree of antibonding interactions with the O atom in the OH intermediate of the ORR. We establish that the local tuning of paired catalysts allows for the reactivity of metal atoms to be specifically modified for desirable reactivity

Responses of Ileal and Fecal Microbiota to Withdrawal of Pancreatic Enzyme Replacement Therapy in a Porcine Model of Exocrine Pancreatic Insufficiency

Little is known regarding the interplay between microbiota and pancreas functions in humans as investigations are usually limited to distal sites, namely the analyses of fecal samples. The aim of this study was to investigate both ileal and fecal microbiota in response to pancreatic enzyme replacement therapy (PERT) in a porcine model of exocrine pancreatic insufficiency (EPI). PERT was stopped for ten days in ileo-cecal fistulated minipigs with experimentally induced EPI (n = 8) and ileal digesta as well as fecal samples were obtained before withdrawal, during withdrawal and after the reintroduction of PERT. Profound community changes occurred three days after enzyme omission and were maintained throughout the withdrawal phase. A reduction in α-diversity together with relative abundance changes in several taxa, in particular increases in Bifidobacteria (at both sites) and Lactobacilli (only feces) were observed. Overall, dysbiosis events from the ileum had accumulating effects in distal parts of the gastrointestinal tract with additional alterations occurring only in the colon. Changes were reversible after continuing PERT, and one week later, bacterial communities resembled those at baseline. Our study demonstrates the rapid and profound impacts of enzyme withdrawal in bacterial communities, contributing to our understanding of the interplay between pancreas function and microbiot

Enhanced CO2 photocatalytic reduction on alkali-decorated graphitic carbon nitride

In this work, visible-light photocatalytic reduction performance of carbon dioxide (CO) on graphitic carbon nitride (g-CN) was significantly promoted by the decoration of potassium hydroxide (KOH) on g-CN. More importantly, the role of KOH was thoroughly discussed via various characterizations, control experiments and density functional theory (DFT) calculations. It was found that KOH decoration did not result in any significant difference regards to the morphology, elemental states, BET surface area and light adsorption of g-CN except a drastically enhanced CO adsorption capacity. The promotion effect of KOH on g-CN was mainly contributed by the hydroxide ion (OH) functioning as both a hole accepter and a driving force to keep a dynamically stable amount of HCO (probably the major form of CO to be reduced) on the surface of the catalyst. Moreover, the different extents of influence of NaOH and KOH on g-CN were revealed and further explained using computational results. This study supplements current understanding on alkali-promoted photocatalytic processes and provides new insights into the mechanism of CO photocatalytic reduction

In vitro evaluation of sodium butyrate on the growth of three Salmonella serovars derived from pigs at a mild acidic pH value

Foodborne zoonotic diseases can be transferred into the food chain at the stage of livestock farming. As an emerging public health challenge, practicable reduction measures in porcine health management for Salmonella are constantly being investigated. This in vitro study aimed to determine the influence of six different sodium butyrate (SB) concentrations (0, 5, 10, 20, 40, and 80 mM) on the growth of three different Salmonella enterica serovars at a constant pH value of 6.0, corresponding to conditions in the pig's hindgut. S. Derby and S. Typhimurium, isolated from a pig farm, and S. Typhimurium DSM 19587, which served as control, were used. Broth microdilution assay was applied to record Salmonella growth in the presence of different SB-concentrations over six different incubation periods (0, 1, 2, 4, 6, and 24 h). Results were quantified in the log colony-forming units (log10 CFU/mL). For 1 h incubation, the addition of SB showed no significant differences in the range of initial Salmonella dose of about 5.7 log10 between concentrations (0–80 mM, 5.26 ± 0.10–5.60 ± 0.07 log10, p > 0.05). After 6 h, for SB addition, the range of Salmonella counts was significantly lower compared to no addition of SB (5–80 mM, p < 0.05), 6.78 ± 0.84–7.90 ± 0.10 log10 for 5 mM, and 7.53 ± 0.04–8.71 ± 0.22 log10 for 0 mM. Moreover, for SB concentrations of 40 and 80 mM, no difference in the range of Salmonella counts over 6 h was obtained (5.23 ± 0.11–5.38 ± 0.05 log10, p > 0.05), and minor Salmonella growth was recorded at the earliest after 24 h incubation. Growth rates for varying SB concentrations and incubation times were confirmed in a similar manner for the three serovars. Obtained results suggest that increasing SB concentrations suppress Salmonella growth for concentrations of 5–20 mM over a 6 h incubation period and for 40 and 80 mM over a 24 h incubation period. When transferring these in vitro findings to the porcine organism, it may be assumed that Salmonella reduction can be achieved by increased butyrate content in the chyme of the large intestine

Impact of the first COVID lockdown on accident- and injury-related pediatric intensive care admissions in Germany - a multicenter study

Children’s and adolescents’ lives drastically changed during COVID lockdowns worldwide. To compare accident- and injury-related admissions to pediatric intensive care units (PICU) during the first German COVID lockdown with previous years, we conducted a retrospective multicenter study among 37 PICUs (21.5% of German PICU capacities). A total of 1444 admissions after accidents or injuries during the first lockdown period and matched periods of 2017–2019 were reported and standardized morbidity ratios (SMR) were calculated. Total PICU admissions due to accidents/injuries declined from an average of 366 to 346 (SMR 0.95 (CI 0.85–1.05)). Admissions with trauma increased from 196 to 212 (1.07 (0.93–1.23). Traffic accidents and school/kindergarten accidents decreased (0.77 (0.57–1.02 and 0.26 (0.05–0.75)), whereas household and leisure accidents increased (1.33 (1.06–1.66) and 1.34 (1.06–1.67)). Less neurosurgeries and more visceral surgeries were performed (0.69 (0.38–1.16) and 2.09 (1.19–3.39)). Non-accidental non-suicidal injuries declined (0.73 (0.42–1.17)). Suicide attempts increased in adolescent boys (1.38 (0.51–3.02)), but decreased in adolescent girls (0.56 (0.32–0.79)). In summary, changed trauma mechanisms entailed different surgeries compared to previous years. We found no evidence for an increase in child abuse cases requiring intensive care. The increase in suicide attempts among boys demands investigation

High Dietary Intake of Rye Affects Porcine Gut Microbiota in a Salmonella Typhimurium Infection Study

Bacterial fermentation of undigested carbohydrates in the hindgut has considerable potential for the stimulation or inhibition of the growth of distinct bacteria within microbiota. The aim of the present study was to evaluate whether high levels of rye affect porcine gut microbiota composition with subsequent effects on the load of Salmonella Typhimurium, an intestinal pathogen with zoonotic relevance. Therefore, forty-two 25-day-old piglets were allocated to two groups and fed a diet containing either 69% wheat or 69% rye for 35 days. One week after introducing the two different diets, the piglets were experimentally infected with Salmonella Typhimurium. The microbiota composition of cecal and fecal samples of the piglets were evaluated 28 days after infection. In the cecum, promoted growth of Bifidobacterium, several lactic acid bacteria and Faecalibacterium prausnitzii were seen in pigs fed the diet containing 69% rye. Bacterial species belonging to the genera Bifidobacterium and Catenisphaera were associated with differing bacterial counts of Salmonella Typhimurium detected in the cecal contents of all piglets in both feeding groups via cultural cultivation. The high intake of rye instead of wheat seems to promote the growth of beneficial intestinal bacteria accompanied by impaired growth conditions for the foodborne pathogen Salmonella Typhimurium

Energy Consumption of Young Military Working Dogs in Pre-Training in Germany

Many factors have specific effects, in varying degrees of intensity, on the metabolic energy requirements of working dogs. Appropriate energy supply adjusted to the requirements of military working dogs at pre-training is a basic prerequisite for working dogs, so they are fully able to exercise. Therefore, more knowledge obtained under standardized conditions would be advantageous. Twenty intact Belgian Shepherds var. Malinois at the age of 12 months were accompanied for four weeks during pre-training (odour detection, obedience training, and protection work) as military working dogs (MWDs) in Germany (ambient temperature about 7.8 °C), and the amount of energy intake was evaluated. To assess changes in body constitution, body weight and shoulder height were measured, and the thickness of subcutaneous fat tissue (SCF), and of Musculus sacrocaudalis dorsalis lateralis (MSCDL), were recorded via ultrasound. Energy intake amounted to, on average, 244 ± 34 kcal/kg body weight (BW)0.75 daily. Increases in body weight, shoulder height, and thickness of the MSCDL, as well as a reduction of SCF thickness lying on the MSCDL, were observed. Changes of body constitution might be attributed to training-induced muscle growth and physiological growth in size. In addition to training intensity, influences of ambient temperature and physiological body growth seemed to be important contributing factors in the supply of energy for MWDs during pre-training

Computational Studies of the Interaction of Carbon Dioxide with Graphene-Supported Titanium Dioxide

The interaction of carbon dioxide (CO2) with titanium dioxide (TiO2) supported on graphene (GR) and epoxy-enhanced graphene (GR-O) was investigated using density functional theory (DFT) calculations and compared with the interaction on unsupported TiO2 systems. Adsorption energies, charge density differences, and activation barriers were calculated. TiO2 clusters, comprising two to four TiO2 units were considered. We show that the carbon support influences the binding energy of CO2 significantly when chemisorbed, and the molecule is bound in a bent VI:614 40 configuration. The epoxy oxygen connection of GR-O with TiO2 leads to a further increase in the binding energy of CO2, as does increasing the size of the TiO2 cluster, due to a higher charge delocalization on the GR sheet

A Field Study Evaluating the Effects of Diclazuril and Oregano Oil for the Prevention of Coccidiosis in Fattening Rabbits

For years, there has been an increasing interest in natural alternatives to the conventional coccidiostats applied as feed additives, which have been used for decades to prevent coccidiosis in poultry and fattening rabbits. This study aimed to compare the possible anticoccidial effects of oregano oil to the established substance diclazuril in growing rabbits. The control group (CG) received a non-supplemented basal compound feed, to which either diclazuril (1 mg/kg; DG) or oregano oil (75 mg/kg; OG) was added. In each of the three trials, subgroups of 50 rabbits each were assigned to one of the three experimental groups (CG, DG and OG). Natural Eimeria infection was monitored weekly by fecal oocyst counts and Eimeria species identification following sporulation. Additionally, the performance parameters were determined at the middle and the end of the trials, and the deceased rabbits were subjected to necropsy. Neither oocyst excretion nor the performance parameters differed significantly between the three experimental groups. Eimeria media, Eimeria magna, Eimeria perforans and Eimeria exigua were identified as the occurring species. The highest animal losses (16.0%) occurred in the OG, while the losses were 12.7% in the DG and 12.0% in the CG. However, these differences were not statistically significant. Overall, neither diclazuril nor oregano oil was superior to the non-supplemented feed. This underlines the importance of diagnostics, as this study’s results indicate that in the absence of the highly pathogenic Eimeria species, economic rabbit rearing and fattening is achievable without the use of coccidiostats