Co/Ni-polyoxotungstate photocatalysts as precursor materials for electrocatalytic water oxidation.

An open-core cobalt polyoxometalate (POM) [(A-α-SiW9O34)Co4(OH)3(CH3COO)3]8-Co(1) and its isostructural Co/Ni-analogue [(A-α-SiW9O34)Co1.5Ni2.5(OH)3(CH3COO)3]8-CoNi(2) were synthesized and investigated for their photocatalytic and electrocatalytic performance. Co(1) shows high photocatalytic O2 yields, which are competitive with leading POM water oxidation catalysts (WOCs). Furthermore, Co(1) and CoNi(2) were employed as well-defined precursors for heterogeneous WOCs. Annealing at various temperatures afforded amorphous and crystalline CoWO4- and Co1.5Ni2.5WO4-related nanoparticles. CoWO4-related particles formed at 300 °C showed substantial electrocatalytic improvements and were superior to reference materials obtained from co-precipitation/annealing routes. Interestingly, no synergistic interactions between cobalt and nickel centers were observed for the mixed-metal POM precursor and the resulting tungstate catalysts. This stands in sharp contrast to a wide range of studies on various heterogeneous catalyst types which were notably improved through Co/Ni substitution. The results clearly demonstrate that readily accessible POMs are promising precursors for the convenient and low-temperature synthesis of amorphous heterogeneous water oxidation catalysts with enhanced performance compared to conventional approaches. This paves the way to tailoring polyoxometalates as molecular precursors with tuneable transition metal cores for high performance heterogeneous electrocatalysts. Our results furthermore illustrate the key influence of the synthetic history on the performance of oxide catalysts and highlight the dependence of synergistic metal interactions on the structural environment.

Pathways towards true catalysts: computational modelling and structural transformations of Zn-polyoxotungstates.

Current catalysis undergoes a paradigm shift from molecular and heterogeneous realms towards new dynamic catalyst concepts. This calls for innovative strategies to understand the essential catalytic motifs and true catalysts emerging from oxidative transformation processes. Polyoxometalate (POM) clusters offer an inexhaustible reservoir for new noble metal-free catalysts and excellent model systems whose structure-activity relationships and mechanisms remain to be explored. Here, we first introduce a new {ZnnNa6-n(B-α-SbW9O33)2} (n = 3-6) catalyst family with remarkable tuning options of the Zn-based core structure and high activity in H2O2-assisted catalytic alcohol oxidation as a representative reaction. Next, high level solution-based computational modelling of the intermediates and transition states was carried out for [Zn6Cl6(SbW9O33)2]12- as a representative well-defined case. The results indicate a radical-based oxidation process with the involvement of tungsten and adjacent zinc metal centers. The {ZnnNa6-n(B-α-SbW9O33)2} series indeed efficiently catalyses alcohol oxidation via peroxotungstate intermediates, in agreement with strong spectroscopic support and other experimental evidence for the radical mechanism. Finally, the high performance of [Zn6Cl6(SbW9O33)2]12- was traced back to its transformation into a highly active and robust disordered Zn/W-POM catalyst. The atomic short-range structure of this resting pre-catalyst was elucidated by RMC modelling of the experimental W-L3 and Zn-K edge EXAFS spectra and supported with further analytical methods. We demonstrate that computational identification of the reactive sites combined with the analytical tracking of their dynamic transformations provides essential input to expedite cluster-based molecular catalyst design.

Predictors of Outcome in Pediatric Osteomyelitis: Five Years Experience in a Single Tertiary Center.

BACKGROUND: Acute haematogenous osteomyelitis is a bacterial infection of bone, which occurs most frequently in children. Outcomes are excellent for the majority of children, but a minority develop complicated osteomyelitis. Predicting which children will develop complicated osteomyelitis remains a challenge, particularly in developed countries where most patients are discharged home after a relatively short period in hospital. METHODS: We conducted a 5-year retrospective case note review of all children aged 3 months to 16 years admitted with a diagnosis of acute haematogenous osteomyelitis. We compared standardized clinical and laboratory parameters in those who developed simple and complicated osteomyelitis. RESULTS: Of the 299 children who met inclusion, 241 (80.6%) had simple and 58 (19.4%) had complicated osteomyelitis. The major predictors of complicated disease were older age, a temperature greater than 38.5°C and a higher C-reactive protein at admission. CONCLUSIONS: A risk prediction model, utilizing information available shortly after hospitalization, allows early identification of children at greatest risk of developing complicated osteomyelitis.

Closer to photosystem II: a Co4O4 cubane catalyst with flexible ligand architecture.

We introduce the novel Co4O4 complex [Co(II)4(hmp)4(µ-OAc)2(µ2-OAc)2(H2O)2] (1) (hmp = 2-(hydroxymethyl)pyridine) as the first Co(II)-based cubane water oxidation catalyst. Monodentate acetate and aqua ligands lend the flexible environment of 1 closest resemblance to photosystem II among its tetranuclear mimics to date. Visible-light-driven catalytic activity of 1 increases with pH value through aqua ligand deprotonation. The Co(II) core combines robustness and stability with flexibility through a new type of water-oxidation mechanism via mobile ligands.

Fevers and the rheumatologist.

Fevers in children are mainly due to infection, malignancy or inflammatory conditions. Rheumatologists have an important role in the care of inflammatory conditions, many of which are associated with fevers. Seven conditions, the hereditary recurrent fever syndromes, have been defined with the presenting symptom of recurring fever, and for which mutation of a single gene has been defined: Chronic infantile neurological articular syndrome (CINCA), Familial cold autoinflammatory syndrome (FACS), Familial Mediterranean fever (FMF), hyperimmunoglobulinemia D (HIDS), Muckle-Wells syndrome (MWS), Pyogenic sterile arthritis and Pyoderma gangrenosum (PAPA) and Tumour necrosis factor receptor-associated periodic syndrome (TRAPS) . These conditions will be discussed in detail in regard to how they fit into the wider picture of pediatric rheumatological conditions, how the diagnoses may be established and the current recommended treatments for each condition.

The Fremantle lead study part 2.

AIM: A 1993 study of blood lead levels (BLLs) in pre-schoolers living in Fremantle showed 25% had BLLs >or= 10 microg/dL. This study compares the 1993 BLLs with a sample of contemporary Fremantle pre-schoolers. METHODS: Pre-schoolers (0-5 years) living in the Fremantle area were recruited from hospital and community settings during 2005. As in the 1993 study, guardians completed a questionnaire concerning demographic, environmental and behavioural variables. BLLs were determined by the same method used in 1993. Statistical analysis compared the 1993 and 2005 samples according to demographic variables and dichotomised BLL. Multivariate linear regression was used to control for confounding variables, and linear regression was used to identify risk factors in the 2005 sample. RESULTS: Community (40) and hospital (60) participants provided blood and completed questionnaires; none had BLLs >or=10 microg/dL. Compared with the 1993 sample, 2005 participants were younger, fewer were aboriginal, more had occupied their homes for over 6 months and more had a habit of putting soil in their mouths. After controlling for these variables, the geometric mean BLL in 2005 remained significantly lower than the 1993 value (1.83 and 6.82 microg/dL respectively). As in 1993, aboriginality, presence of participants during home renovation, occupancy of home less than 6 months and living <200 m from a main road were associated with higher mean BLLs. CONCLUSIONS: The reassuring decline in the mean BLL between the1993 and 2005 samples is likely associated with the phasing out of leaded petrol. Future research should concentrate on monitoring groups at higher risk.