Visible-light driven oxidation of gaseous aliphatic alcohols to the corresponding carbonyls via TiO2 sensitized by a perylene derivative

Sensitized P25 TiO₂ was prepared by wet impregnation with a home-prepared perylene dye, i.e., N,N′-bis(2-(1-piperazino)ethyl)-3,4,9,10-perylene-tetracarboxylic acid diimide dichloride (PZPER). Energy levels of PZPER were found to be compatible with those of TiO₂ allowing fast electron transfer. The obtained catalyst has been characterized and used in the gas-phase partial oxidation of aliphatic primary and secondary alcohols, i.e., methanol, ethanol, and 2-propanol. The reaction was carried out under cut-off (λ?>?400 nm) simulated solar radiation in O₂ atmosphere. The perylene derivative allowed a good absorbance of visible radiation thanks to its low optical energy gap (2.6 eV) which was evaluated by cyclic voltammetry. The optimal organic sensitizing amount was found to be 5.6 % w/w in terms of yield in carbonyl derivatives. Moreover, no change in reactivity/selectivity was observed after 10-h irradiation thus confirming the catalyst stability. Yields into formaldehyde, acetaldehyde, and acetone were 67, 70, and 96 %, respectively. No significant amounts of organic byproducts were detected but for methanol oxidation, whereas a minor amount of the substrate degraded to CO₂.     

Wind- and tide-induced currents in the Stagnone lagoon (Sicily)

The hydrodynamic circulation is analyzed in the coastal lagoon of Stagnone di Marsala, a natural reserve located in the north-western part of Sicily, using both experimental measurements and numerical simulations. Field measurements of velocities and water levels, carried out using an ultrasound sensor (3D), are used to validate the numerical model. A 3D finite-volume model is used to solve the Reynolds-averaged momentum and mass balance differential equations on a curvilinear structured grid, employing the k–e{\varepsilon} turbulence model for the Reynolds stresses. The numerical analysis allows to identify the relative contribution of the forces affecting the hydrodynamic circulation inside the lagoon. In the simulations only wind and tide forces are considered, neglecting the effects of water density changes. Two different conditions are considered. In the first both the wind stress over the free-surface and the tidal motion are imposed. In the second the wind action is neglected, to separately analyze the tide-induced circulation. The comparison between the two test cases highlights the fundamental role of the wind on the hydrodynamics of the Stagnone lagoon, producing a strong vertical recirculation pattern that is not observed when the flow is driven by tides only.     

Solicitation displays reliably reflect oxidative damage in barn swallow nestlings

Reproduction entails parental decisions over allocation of limiting resources. ‘Begging’ solicitation displays by the offspring have been hypothesised to evolve as reliable indicators of quality, allowing parents to adopt optimal allocation strategies. To function as such, however, begging signals must covary with offspring traits that affect viability. Here we tested whether oxidative damage of nestling barn swallows predicts begging bout duration, call amplitude and intensity of postural displays both under normal food provisioning and under food shortage. Oxidative damage as determined by normal metabolism, pathological conditions and functioning of the immune system can serve as a comprehensive indicator of offspring condition because it can profoundly affect viability, senescence and reproduction. Begging bout duration was negatively predicted by oxidative damage but only after food deprivation. Postural begging negatively covaried with oxidative damage, at least when nestlings were confronted with related nest mates. Plasma antioxidant capacity did not predict begging behaviour. Thus, we show for the first time that behavioural begging covaries with a comprehensive index of chick condition, lending support to reliability of such begging traits also as signals of quality rather than need or hunger only. Future studies are candidate to decouple the effect of hunger state and individual condition on behavioural begging.     

Prenatal diagnosis of recurrence of cystic hygroma with normal chromosomes

Cyst-like masses in the neck and back region, simulating an encephalocele, were detected by midtrimester ultrasound examinations in two sib fetuses. After termination, the fetuses were found to have large cystic hygromas. The present observation strongly suggests the existence of an autosomal recessive type of cystic hygroma.     

Prenatal diagnosis of X-linked retinitis pigmentosa (RP) in five pregnancies at risk

Five pregnancies at risk for X-linked retinitis pigmentosa (RP) have been monitored by first-trimester prenatal diagnosis using DNA markers flanking the RP2 and RP3 loci. Three affected and two unaffected fetuses, including a female carrying a wild-type genotype, were predicted on the basis of marker segregation and estimation of the recombination fraction.     

Azo-dyes photocatalytic degradation in aqueous suspension of TiO2 under solar irradiation

The photodegradation of two common and very stable azo-dyes, i.e. methyl-orange (C₁₄H₁₄N₃SO₃Na) and orange II (C₁₆H₁₁N₂SO₄Na), is reported. The photocatalytic oxidation was carried out in aqueous suspensions of polycrystalline TiO₂ irradiated by sunlight. Compound parabolic collectors, installed at the “Plataforma Solar de Almería” (PSA, Spain) were used as the photoreactors and two identical reacting systems allowed to perform photoreactivity runs for the two dyes at the same time and under the same irradiation conditions. The disappearance of colour and substrates together with the abatement of total organic carbon content was monitored. The main sulfonate-containing intermediates were found to be in lower number in respect to those obtained under artificial irradiation. In particular there were no more evidence of the presence of hydroxylated transients. The dependence of dye photooxidation rate on: (i) substrate concentration; (ii) catalyst amount; and (iii) initial pH was investigated. The influence of the presence of strong oxidant species (H₂O₂, S₂O₈²⁻) and some ions (Cl⁻, SO₄²⁻) on the process was also studied.     

Chlorinated herbicide (triallate) dehalogenation by iron powder

The reductive degradation of a chlorinated herbicide by iron powder was investigated at lab scale. The studied substrate was triallate (S-2,3,3-trichloroallyl di-isopropyl thiocarbamate) which contains a trichloroethylene moiety potentially reducible by zero-valent iron. Degradation reactions were carried out in batch, at 25 degrees C, in the absence of oxygen, by contacting electrolytic iron powder (size range: 20-50 microm) with a triallate aqueous solution (2.5 mgl(-1)). Herbicide decay, corresponding evolutions of TOC, TOX and chloride ion release were regularly monitored throughout the reactions. Furthermore, the main degradation by-products were identified by HPLC/MS. The results showed that, after 5 days, herbicide degradation extent was about 97% and that the reaction proceeded through the formation of a dechlorinated alkyne by-product (S-2-propinyl di-isopropyl thiocarbamate) resulting from the complete dechlorination of triallate. The subsequent reduction of such an alkyne intermediate gave S-allyl di-isopropyl thiocarbamate as main end by-product. The identified by-products suggested that dechlorination took place mainly via reductive beta-elimination. However, as traces of dichloroallyl di-isopropyl thiocarbamate were also detected, a role, although minor, was assigned even to hydrogenolysis in the overall dechlorination process.     

Testing the extended biotic index in Slovakia: consistency, advantages, and limitations versus the saprobic assessment method of water quality.

The European Union Water Framework Directive requires the achievement of environmental objectives for the ecological quality of water bodies. A comparable implementation of the Directive throughout member countries of the European Union is necessary to verify equal protection of surface waters. The Directive specifies that member states determine ecological quality by means of biological indices. To improve comparability of water quality assessment, this research carried out an intercalibration trial between the Slovak Saprobic Index and the Italian protocol of the Extended Biotic Index, as part of a cooperative program between Italy and the Slovak Republic. When assessing streams with no or low pollution, statistics showed similar results for both methods. In contrast, the comparison of indices was not accurate in the case of severely affected waters. Reliable conversion formulas are feasible to transform the Italian Extended Biotic Index into the Slovak Saprobic Index, and not vice versa.     

Spatial error propagation when computing linear combinations of spectral bands: The case of vegetation indices

The collection of accurate and timely information on land use, crops, forest and vegetation are increasingly based on remote sensing spectral measurements produced by satellites. The most recent spacecrafts like the Earth Observing 1 (EO-1) produce a rich source of information being endowed with hyperspectral sensors that can provide up to 200 or more channels. In many instances such a multivariate signal has to be reduced to just one single value per pixel representing a particular characteristic of land. Linear combinations of bands are the general form of many indices. Since each individual image used to construct indices contains errors, when combined they produce a propagation of errors, a process that can distort a final output map. In this paper we measure the extent of error propagation when building linear vegetation indices. We consider three types of indices: the difference vegetation index (DVI), selected Kauth-Thomas indices (SBI, GVI and WET), and principal components, using benchmarking examples taken from the remote sensing literature. The main implication emerging from these examples is that the SBI and the first principal component are the indices more prone to error propagation. The formalization presented here allows a user to derive measures of error propagation in cases where technical characteristics of a sensor and physical characteristics of a landscape are known. These results can help a user to choose between alternative vegetation indices, and to associate a measure of reliability with such indices.