Water Oxidation Catalysis by Molecular Metal-Oxides

Abstract Water oxidation catalysis is recognized as the bottleneck for the development of efficient devices based on artificial photosynthesis, that is the light driven water splitting into hydrogen and oxygen. A recent breakthrough in this field, is the development of a molecular, fast and robust water oxidation catalyst namely a fully inorganic tetranuclear ruthenium complex with polyoxometalate ligands. The crystal structure of [Ru4(μ-O)4(μ-OH)2(H2O)4(SiW10O36)2]10-, 1, evidences the entrapment of an adamantane like, tetranuclear ruthenium(IV)-oxo core, by two decatungtosilicate units. Several spectroscopic techniques confirm the maintenance of the structure in aqueous solution. In the presence of Ce(IV) as sacrificial electron acceptor, 1 catalyzes water oxidation to oxygen, showing up to 500 turnovers and a turnover frequency of 0.125 s-1. The synergistic effect of the four ruthenium centres has a fundamental effect on such astounding performance, as confirmed by spectroscopic and computational characterization of five competent intermediates involved in the catalytic cycle, in strict analogy with the natural paradigm of the oxygen evolving centre in Photosystem II. Interestingly, 1 efficiently catalyzes water oxidation in the presence of photogenerated oxidants, as well; this fundamental feature is probably related to very fast hole scavenging of anionic 1 from cationic photogenerated oxidants, such as Ru(bpy)33+. Thus, 1 is an ideal candidate for the assembly of high efficient oxygenevolving anodes into nanostructured devices for artificial photosynthesis

Reduction in finger blood flow induced by hand-transmitted vibration: effect of hand elevation

Objectives This study investigated the effect of hand elevation on reductions in finger blood flow (FBF) induced by hand-transmitted vibration. Methods Fourteen males attended six sessions on six separate days, with a control sessions and a vibration session (125-Hz vibration at 44 ms 2 r.m.s.) with the right hand supported at each of three elevations: 20 cm below heart level (HL), at HL, and 20 cm above HL. Finger blood flow on the left and right hand was measured every 30 s during each 25-minute session comprised of five periods: (i) no force and no vibration (5 minutes), (ii) 2-N force and no vibration (5 minutes), (iii) 2-N force and vibration (5 minutes), (iv) 2-N force and no vibration (5 minutes), and (v) no force and no vibration (5 minutes). Results Without vibration, FBF decreased with increasing elevation of the hand. During vibration of the right hand, FBF reduced on both hands. With elevation of the right hand, the percentage reduction in FBF due to vibration (relative to FBF on the same finger at the same elevation before exposure to vibration) was similar on the middle and little fingers of both hands. After cessation of vibration, there was delayed return of FBF with all three hand heights. Conclusions Vibration of one hand reduces finger blood flow on both exposed and unexposed hands, with the reduction dependent on the elevation of the hand. The mechanisms responsible for vibration-induced reductions in FBF seem to reduce blood flow as a percentage of the blood flow without vibration. Tasks requiring the elevation of the hands will be associated with lower FBF, and the FBF will be reduced further if there is exposure to hand-transmitted vibration

Investigating alcohol consumption during pregnancy for the prevention of Fetal Alcohol Spectrum Disorders (FASD)

The term FASD (Fetal Alcohol Spectrum Disorders) is used to describe the entire spectrum of pathologies and disorders caused by alcohol exposure in uterus. Alcohol assumed in pregnancy passes directly through the placental barrier causing a broad range of symptoms whose severity can greatly vary in degree. The alcohol teratogenic effect may result in physical damage and specific facial anomalies, growth delays, neurological defects along with intellectual disabilities and behavioral problems. Children affected show difficulties in verbal learning, memory, visual-spatial abilities, attention, logic and math abilities, information processing, executive functions as well as in many other domains and in general coping with daily life. Total abstention from alcohol during pregnancy is strongly recommended, as a safe threshold of consumption has not been established yet. Hence, the early identification of alcohol consumption in pregnancy is crucial. Specific methodologies to overcome difficulties related to the identification of alcohol behavior in pregnant women are needed and intervention protocols should be implemented to prevent damage in offsprings. This paper gives an overview on this pathology, from clinical delineation to epidemiology and risk factors with a special focus to promote alcohol-free pregnanc

Botulinum toxin treatment in glaucomatous patients: a pilot study

PURPOSE: The purpose was to evaluate the efficacy of the treatment of iatrogenic entropion (IE), in patients affected by primary open angle glaucoma (POAG), by botulinum toxin injections (BTI). PATIENTS AND METHODS: 20 patients of the "Glaucoma Center" of the Hospital "Umberto I" (Rome) were examined. These patients had POAG and used prostaglandin analogues (PA). Mean age was 75.5 years old (range 68-83); they had been suffering from PAOG since 10 years and were not affected by other relevant systemic diseases. One to three BTI were made into the lower orbicularis muscle using a 0.3 G needle (0.025 to 0.05 units for each injection site). RESULTS: The results were particularly significant in 18 out of 20 patients. Two patients showed slight improvements. A rating scale ranging from 0 to 6 points (0 corresponded to 'no effect' and 6 to the 'complete' resolution of the entropion) was used to evaluate the goals of the treatment. The average rating was 5.37 points. CONCLUSIONS: The entropion due to glaucoma therapy with PA can be successfully treated with BTI in the orbicularis muscle, despite offering temporary therapeutic effects

An overview of low back pain and occupational exposures to whole-body vibration and mechanical shocks

This paper offers an overview of the relation of low back pain (LBP) to occupational exposures to whole-body vibration (WBV) and mechanical shocks. LBP is a condition of multifactorial origin and is a very common health problem in the general population. Among occupational risk factors, epidemiological studies of driving occupations have provided evidence for strong associations between LBP and occupational exposures to WBV and mechanical shocks. Since it is hard to separate the contribution of WBV exposure to disorders in the lower back from that of other individual, ergonomic or psychosocial risk factors, a quantitative exposure-response relationship for WBV cannot be outlined precisely. Experimental research has provided biodynamic support to the findings of epidemiological studies, showing that in controlled laboratory conditions exposure to WBV can cause mechanical overload to the human spine. The EU Directive on mechanical vibration has established daily exposure action and limit values to protect the workers against the risk from WBV. There is some evidence that the EU exposure limit values are excessive, so much so that an elevated risk of LBP has been found for WBV exposures beneath the EU limit values. In the Italian arm of the EU VIBRISKS prospective cohort study of professional drivers, measures of internal lumbar load (compressive and shear peak forces), calculated by means of anatomy-based finite-element models, were found better predictors of the occurrence over time of low back disorders than the metrics of external exposure suggested by the EU Directive on mechanical vibration. Further biodynamic and epidemiological studies are needed to validate the findings of the VIBRISKS study