Ultrasound and microwave-assisted extraction of metals from sediment: a comparison with the BCR procedure

In this paper we investigate alternatives to mechanical stirring for the extraction of the mobile fraction of metals from sediment, and analyze whether these techniques can reduce extraction time and improve reproducibility. We compare the quantities of metal extracted from BCR601 and BCR701 certified sediments using ultrasound bath, microwave-assisted extraction and the first step in the certified BCR sequential extraction procedure. Some environmentally important not-certified metals such as As, Mn, Co, Fe and Al have been included in this study. In the case of microwave-assisted extraction, we compare tests in which samples are exposed to constant, low power irradiation with tests using pulsed high power.

In the tests using the ultrasound bath, less metal was extracted than with the other extractive techniques and standard deviations were comparable to those obtained with the BCR procedure; in assays using microwaves at constant power, extraction efficiencies were different for different metals and for different reference materials and, in some cases, standard deviations were higher than those for the reference method. In contrast, tests with microwaves and constant temperature produced encouraging results: R.S.D.s lay in the 2–4% range, both for certified and not-certified metals; these values are very low compared to those for the reference method. Extraction efficiencies for certified metals were close to 100% for Cd, Zn, Cu and Ni and around 80% for Pb and Cr.     

Microcantilevers and organic transistors: two promising classes of label-free biosensing devices which can be integrated in electronic circuits

Most of the success of electronic devices fabricated to actively interact with a biological environment relies on the proper choice of materials and efficient engineering of surfaces and interfaces. Organic materials have proved to be among the best candidates for this aim owing to many properties, such as the synthesis tunability, processing, softness and self-assembling ability, which allow them to form surfaces that are compatible with biological tissues. This review reports some research results obtained in the development of devices which exploit organic materials' properties in order to detect biologically significant molecules as well as to trigger/capture signals from the biological environment. Among the many investigated sensing devices, organic field-effect transistors (OFETs), organic electrochemical transistors (OECTs) and microcantilevers (MCLs) have been chosen. The main factors motivating this choice are their label-free detection approach, which is particularly important when addressing complex biological processes, as well as the possibility to integrate them in an electronic circuit. Particular attention is paid to the design and realization of biocompatible surfaces which can be employed in the recognition of pertinent molecules as well as to the research of new materials, both natural and inspired by nature, as a first approach to environmentally friendly electronics.     

Chemistry of nitrated lipids: remarkable instability of 9-nitrolinoleic acid in neutral aqueous medium and a novel nitronitrate ester product by concurrent autoxidation/nitric oxide-release pathways

Despite the mounting interest in nitrolinoleic acids and related nitrated polyunsaturated fatty acids as a novel class of bioactive signaling lipids, their chemistry and metabolic fate have remained poorly elucidated. Herein, we report an expedient nitroselenenylation/oxidation route to 9-nitrolinoleic acid (1) and 10-nitrolinoleic acid (2), which enabled comparative product studies under physiologically relevant conditions. Under biomimetic conditions, 1 decayed at an unusually fast rate to give the hydroxy-, keto-, and nitronitrate ester derivatives 3, 4, and 5 as main products, identified by ESI-MS and 2D NMR spectroscopy, including (1)H, (15)N HMBC experiments on the (15)N-labeled derivatives. The 13-nitrato functionality in 5 suggested partitioning of 1 between concurrent peroxidation and nitric oxide (NO)-release pathways. Lipid 2 decayed at a much slower rate giving only the hydroxynitro derivative 6 as an isolable product. Diphenylpicrylhydrazide (DPPH) radical quenching experiments and DFT computations concurred to support a higher H-atom donating ability of 1 versus 2, due to more effective stabilization of the resulting pentadienyl radical by the terminal nitro group. The markedly different stability of isomeric nitrolinoleic acids disclosed in the present study may provide an explanation for the previous identification of 2, but not 1, in body fluids and offers a key for future insights into the biological activities of nitrated lipids.     

Mass Spectrometry-Based Peptide Profiling of Haemolymph from Pterostichus melas Exposed to Pendimethalin Herbicide

Pendimethalin-based herbicides are used worldwide for pre-emergence selective control of annual grasses and weeds in croplands. The endurance of herbicides residues in the environment has an impact on the soil biodiversity and fertility, also affecting non-target species, including terrestrial invertebrates. Carabid beetles are known as natural pest control agents in the soil food web of agroecosystems, and feed on invertebrates and weed seeds. Here, a mass spectrometry untargeted profiling of haemolymph is used to investigate Pterostichus melas metabolic response after to pendimethalin-based herbicide exposure. Mass spectrometric data are examined with statistical approaches, such as principal component analysis, for possible correlation with biological effects. Those signals with high correlation are submitted to tandem mass spectrometry to identify the associated biomarker. The time course exposure showed many interesting findings, including a significant downregulation of related to immune and defense peptides (M-lycotoxin-Ls4a, Peptide hormone 1, Paralytic peptide 2, and Serine protease inhibitor 2). Overall, the observed peptide deregulations concur with the general mechanism of uptake and elimination of toxicants reported for Arthropods.     

Chemical Compositions and Antioxidant Activities of Essential Oils,and Their Combinations,Obtained from Flavedo By-Product of Seven Cultivars of Sicilian Citrus aurantium L.

In this work, seven Citrus aurantium essential oils (EOs) derived from flavedo of cultivars ‘Canaliculata’, ‘Consolei’, ‘Crispifolia’, ‘Fasciata’, ‘Foetifera’, ‘Listata’, and ‘Bizzaria’ were investigated. EOs were also combined in 1:1 (v/v) ratio to identify possible synergism or antagonism of actions. GC-MS analysis was done to investigate Eos’ phytochemical profiles. The antioxidant activity was studied by using a multi-target approach based on FRAP, DPPH, ABTS, and β-carotene bleaching tests. A great difference was observed in EOs’ phytochemical profiles. d-limonene (33.35–89.17%) was the main monoterpene hydrocarbon, and α-Pinene, β-myrcene, and β-linalool were identified in almost all samples. Among EOs, only C3 showed high quantitative and qualitative variability in its chemical composition. The chemical diversity of EOs was also demonstrated by PCA and HCA statistical analysis. Samples C2, C4, C5, C6, and C7 were statistically similar to each other, while C1 and C3 were characterized as having a different amount of other compounds and oxygenated monoterpenes, respectively, with respect to the other EOs mentioned. The global antioxidant score (GAS) revealed that among the tested EOs, C. aurantium ‘Fasciata’ EO had the highest antioxidant potential, with a GAS value of −0.47, whereas among combinations, the EO obtained by mixing ‘Canaliculata’ + ‘Bizzaria’ was the most active. Comparison by theoretical and real data on inhibitory concentration (IC₅₀) and FRAP values did not reveal any significant effect of synergism or antagonism of actions to be valid in all biological applied tests. These findings, considered together, represent an important starting point to understand which compounds are responsible for the activities and their future possible industrial application.     

On the curvature of a generalization of contact metric manifolds

Summary We consider a genaralization of contact metric manifolds given by assignment of 1-formsη¹, . . . ,η^sand a compatible metric gon a manifold. With some integrability conditions they are called almost<span style='font-size:10.0pt;font-family:"Monotype Corsiva"; mso-bidi-font-family:"Monotype Corsiva"'>S-manifolds. We give a sufficient condition regarding the curvature of an almost<span style='font-size:10.0pt;font-family:"Monotype Corsiva";mso-bidi-font-family: "Monotype Corsiva"'>S-manifold to be locally isometric to a product of a Euclidean space and a sphere.     

Balanced and strongly balanced Pk-designs

Given a graph $G$, a G-decomposition of the complete graph $K_v$ is a set of graphs, all isomorphic to $G$, whose edge sets partition the edge set of $K_v$. A $G$-decomposition of $K_v$ is also called a G-design and the graphs of the partition are said to be the blocks. A $G$-design is said to be balanced if the number of blocks containing any given vertex of $K_v$ is a constant.In this paper the concept of strongly balanced G-design is introduced and strongly balanced path-designs are studied. Furthermore, we determine the spectrum of those path-designs which are balanced, but not strongly balanced.     

Oxygen electrodes in fused salts: Investigation and mechanistic remarks on the system (Ni)O2, H2O/OH− in the (Na,K)NO3 eutectic melt

A potentiometric investigation on the system (Ni)O₂, H₂O/OH^? was carried out within the temperature range 513?T?636 K in the (Na, K)NO₃ equimolar mixture containing OH^? ions in the concentration range 5×10^?6<[OH^?]<10^?1m and flushed with a mixture of O₂ and H₂O at variable partial pressures. The system has been found to behave reversibly in all hydroxide concentration and temperature intervals studied with respect to all the species involved in the over-all electrode reaction ½ O₂+H₂O+2e^?=2OH^? so that the following nernstian relationship could be written E=E_O2,H₂O/OH^?+RT/Fln{[O₂]^1/4[H₂O]^1/2/[OH^?]} This potentiometric behaviour was tentatively interpreted on the basis of mechanistic models involving, in some steps, solid nickel oxides formed on the electrode surface by contact with the melt. The actual formation and existence of these compounds on the electrode surface under the given experimental conditions was proved by a proper XPS investigation.     

A Light-Induced Decarboxylative-Elimination of Substituted Maleimides as a Strategy Towards Triggered Photorelease

Herein we report on photodecarboxylations of various substituted maleimides, resulting in an elimination reaction. Furthermore, we establish facile wavelength tunability through modulation of the maleimide double bond substituents. We envisage that these versatile reagents, which are readily constructed and diversified by nucleophilic substitution reactions on bromomaleimides, will offer new opportunities for triggered photorelease.