Mechanisms of nanophase-induced desorption in LDI-MS. A short review

Nanomaterials are frequently used in laser desorption ionization mass spectrometry (LDI-MS) as DI enhancers, providing excellent figures of merit for the analysis of low molecular weight organic molecules. In recent years, literature on this topic has benefited from several studies assessing the fundamental aspects of the ion desorption efficiency and the internal energy transfer, in the case of model analytes. Several different parameters have been investigated, including the intrinsic chemical and physical properties of the nanophase (chemical composition, thermal conductivity, photo-absorption efficiency, specific heat capacity, phase transition point, explosion threshold, etc.), along with morphological parameters such as the nanophase size, shape, and interparticle distance. Other aspects, such as the composition, roughness and defects of the substrate supporting the LDI-active nanophases, the nanophase binding affinity towards the target analyte, the role of water molecules, have been taken into account as well. Readers interested in nanoparticle based LDI-MS sub-techniques (SALDI-, SELDI-, NALDI- MS) will find here a concise overview of the recent findings in the specialized field of fundamental and mechanistic studies, shading light on the desorption ionization phenomena responsible of the outperforming MS data offered by these techniques

Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide: 1. Selectivity enhancement by aliphatic alcohols

Oxygenated aqueous suspensions of home-prepared (HP) and commercial TiO2 catalysts were used in a batch photoreactor for carrying out the oxidation of benzyl alcohol (BA) and 4-methoxybenzyl alcohol (MBA) under different operative conditions. HP catalysts were synthesized from TiCl4 and underwent a hydrolysis treatment of different times under mild conditions. The textural characterization of catalysts was carried out with XRD, SEM observations, BET surface area and porosity measurements. For both alcohols the main oxidation products were the corresponding aromatic aldehydes and CO2. The HP catalysts exhibited selectivity values towards the aldehyde production up to 28% (BA conversion: 50%) and 41% (MBA conversion: 65%), about four times higher than those of commercial TiO2. The addition of an aliphatic alcohol (methanol, ethanol, 2-propanol or tert-butanol) in small amounts with respect to water decreased the overall oxidation rate of aromatic alcohols but enhanced the selectivity for aldehyde formation up to 1.5 times. The reactivity results suggest that: (i) the aromatic alcohol molecules interact with the TiO2 surface in different ways that eventually determine two parallel reaction pathways (partial oxidation or mineralization); (ii) the aliphatic alcohols preferentially compete with aromatic alcohols for the mineralizing pathway.Peer reviewe

Optimization of coupled advanced oxidation processes and activated carbons for purification of salt water

Photocatalysis, ozonation and activated carbons were investigated separately and in combination as tools for the purification of polluted salt water. Coupling different processes enables to overcome many drawbacks related to the use of the single technologies and at the same time to exploit possible synergistic effects. In this work a kinetic analysis was performed for modelling the degradation of 4-nitrophenol (4NP) as a probe pollutant molecule in synthetic seawater. Thus, the optimum synergistic conditions of the three processes acting together were determined and discussed

Dynastic Measures of Intergenerational Mobility

We suggest a simple and fexible criterion to assess relative inter-generational mobility. It accommodates different types of outcomes, such as (continuous) earnings or (discrete and ordinal) education levels, and captures dynastic improvements of such outcomes at different points of the initial distribution. We provide dominance characterizations - for instance on the relative progress made by women vs.men - that are consistent with social preferences upon desirable patterns of mobility. We suggest an application on Indonesia. Using the IFLS data, we match parents observed in 1993 to their children in 2014, providing one of the rare intergenerational mobility analyses based on a long panel in the context of a developing country. Results indicate that mobility in terms of education and potential earnings was markedly at the advantage of women. The bulk of the population came out of illiteracy, possibly due to largescale education reforms, but the relative educational mobility was regressive, which considerably reduced the progressivity of mobility in terms of potential earnings

Fatty acid neutral losses observed in tandem mass spectrometry with collision-induced dissociation allows regiochemical assignment of sulfoquinovosyl-diacylglycerols

A full characterization of sulfoquinovosyldiacylglycerols (SQDGs) in the lipid extract of spinach leaves has been achieved using liquid chromatography/electrospray ionization-linear quadrupole ion trap mass spectrometry (MS). Low-energy collision-induced dissociation tandem MS (MS/MS) of the deprotonated species [M - H]- was exploited for a detailed study of sulfolipid fragmentation. Losses of neutral fatty acids from the acyl side chains (i.e. [M - H - RCOOH]-) were found to prevail over ketene losses ([M - H - R'CHCO]-) or carboxylates of long-chain fatty acids ([RCOO]-), as expected for gas-phase acidity of SQDG ions. A new concerted mechanism for RCOOH elimination, based on a charge-remote fragmentation, is proposed. The preferential loss of a fatty acids molecule from the sn-1 position (i.e. [M - H - R1COOH]-) of the glycerol backbone, most likely due to kinetic control of the gas-phase fragmentation process, was exploited for the regiochemical assignment of the investigated sulfolipids. As a result, 24 SQDGs were detected and identified in the lipid extract of spinach leaves, their number and variety being unprecedented in the field of plant sulfolipids. Moreover, the prevailing presence of a palmitic acyl chain (16:0) on the glycerol sn-2 position of spinach SQDGs suggests a prokaryotic or chloroplastic path as the main route for their biosynthesis

Hydrophilic interaction and reversed phase mixed-mode liquid chromatography coupled to high resolution tandem mass spectrometry for polar lipids analysis

A hydrophilic interaction liquid chromatography (HILIC) fused-core column (150 × 2.1 mm ID, 2.7 μm particle size) and a short reversed-phase liquid chromatography (RPLC) column (20 mm × 2.1 mm ID, 1.9 μm) were serially coupled to perform mixed-mode chromatography (MMC) on complex mixtures of phospholipids (PL). Mobile phase composition and gradient elution program were, preliminarily, optimized using a mixture of phosphatidylcholines (PC), phosphatidylethanolamines (PE), their corresponding lyso-forms (LPC and LPE), and sphingomyelins (SM). Thus a mixture of PC extracted from soybean was characterized by MMC coupled to electrospray ionization (ESI) high-resolution Fourier-transform mass spectrometry (FTMS) using an orbital trap analyzer. Several previously undiscovered PC, including positional isomers (i.e. 16:0/19:1 and 19:1/16:0) of PC 35:1 and skeletal isomers (i.e. 18:1/18:2 and 18:0/18:3) of PC 36:3 were identified. Therefore, high-resolution MS/MS spectra unveiled the occurrence of isomers for several overall side chain compositions. The proposed MMC-ESI-FTMS/MS approach revealed an unprecedented capability in disclosing complexity of an actual lipid extract, thus representing a very promising approach to lipidomics

Photocatalytic ozonation under visible light for the remediation of water effluents and its integration with an electro-membrane bioreactor

Photocatalysis and photocatalytic ozonation under visible light have been applied for the purification of a complex aqueous matrix such as the grey water of Masdar City (UAE), by using N-doped brookite-rutile catalysts. Preliminary runs on 4-nitrophenol (4-NP) solutions allowed to test the reaction system in the presence of a model pollutant and to afford the relevant kinetic parameters of the process. Subsequently, the remediation of grey water effluent has been evaluated in terms of the reduction of total organic carbon (TOC) and bacterial counts. The concentration of the most abundant inorganic ionic species in the effluent has been also monitored during reaction. Photocatalytic ozonation under visible light allowed to reduce the TOC content of the grey water by ca. 60% in the optimized experimental conditions and to reduce the total bacterial count by ca. 97%. The extent of TOC mineralization reached ca. 80% when the photocatalytic ozonation occurred downstream to a preliminary electro-membrane bioreactor (eMBR). Coupling the two processes enhanced the global efficiency. In fact, the eMBR treatment lowered the turbidity and the organic load of the effluent entering the photocatalytic ozonation treatment, which in turn enhanced the extent of purification and disinfection

Novità speleologiche,idrologiche e naturalistiche dalla Palude del Capitano (pSIC IT9150013), costa neretina

EnThe speleodivers of the Centro di Speleologia Sottomarina “Apogon ” and the researchers of the Di.S.Te.B.A.-University of Lecce,conducted a joint exploration of the coastal cenote “Palude del Capitano”,with particular attention to the tangled,submerged tunnels that connect this unique aquatic environment to the open sea.The study performed since September 2001 for one year of observations resulted in:a photo-video documentation on the biotope;an exploration and a photo-video-topographic documentation of the tunnels;a periodical control of the physico-chemical water factors in several sites of the aquatic system;a florofaunistic census.12 out of the 35 taxa identi fied were found for the first time in this biotope.Many of them belonged to planctonic micro-(size <200 µm)and macro- fauna (size ≥200 µm).The community lives in particular stable conditions through the whole year.Temperature varies between 18.8 and 21.6 °C;salinity does not exceed over 20.50 0 /00 ;pH was comprised between 7.00 and 7.65.Among the sessile invertebrates,we con firm the presence,near the entrances of the western tunnels, of a conspicuous population of the brackish water hydroid Cordylophora caspia, already observed during a previous study on this biotope.Among ichtiological fauna,the presence of the mediterranean cyprinodontid Aphanius fasciatus has been con firmed as well by this study.This species is included in Annex II and III of the European Council Directive 92/43.The pond is characterised by inconstant hypothermal springs that periodically supply the aquatic ecosystem with underground brackish water.The chemical nature of this water is still unknown,but it most prob- ably results in the sulphuric freshwater even if mixed to the salt water coming from the sea.The explored tunnels open their submerged entrances on the western side of the pond and connect the aquatic system to the sea on an approximate distance of 800 m.It is possible to explore them only for a few m because the tunnels become then narrows and dangerous for the speleodive activity.The “Palude del Capitano” pond is an interesting example of speleogenetic phenomenon of hyperkarstic origin that assumes a remarkable territorial importance.It has been classi fied as a paralic system with a con finament grade ranging from IV to VI.The preservation of this unique aquatic biotope should seriously be taken into consideration by the relevant national competent authorities and be the focus of their attention.ItViene riportato uno studio della Palude del Capitano esteso ai cunicoli sommersi che,dal lato W,collegano questo ambiente al mare aperto distante circa 800 m. La ricerca ha consentito di realizzare una video-documentazione del sito nelle varie stagioni,l’esplorazione della porzione praticabile delle condotte sommerse, il monitoraggio di parametri fisico-chimici dell ’acqua in vari punti,un censimento floro-faunistico.12 dei 35 taxa identi ficati sono stati segnalati per la prima volta in questo biotopo.Gran parte di essi appartiene alla fauna micro-e macroplanctonica.La palude è caratterizzata dalla presenza di sorgenti ad attività intermittente che probabilmente mantengono condizioni stabili durante tutto l’anno.Viene confermata la presenza dell’idroide Cordylophora caspia.Tra i pesci si segnala Aphanius fasciatus ,incluso nella lista delle specie protette secondo la Direttiva 92/43/CEE.sedimenti più recenti.queste ultime sono date dalle Calcareniti di Gravina del Pleistocene inferiore.chiude il ciclo geologico un complesso di depositi di spiaggia e di piana costiera generatisi in fasi eustatico-tettoniche riferibili al Pleistocene superiore