Effect of gamma irradiation on gas-ionic liquid and water-ionic liquid interfacial stability

The effect of γ-radiation on gas-ionic liquid (IL) and water-IL interfacial stability was investigated. Three phosphonium-based ILs, which vary considerably in their viscosity, conductivity and miscibility with water, were examined. The gas phase above the IL samples (headspace gas) was analyzed using gas chromatography with a mass spectrometer detector while the changes in the IL and aqueous phases were followed by conductivity measurements and Raman spectroscopy. For the gas-IL systems, the headspace samples showed trace amounts of the radiolytic decomposition products of the ILs that were small and volatile enough to become airborne. The type of cover gas, air or Ar, had no effect on the gas speciation. Negligible changes in the conductivity and the Raman spectra of the IL phase due to irradiation indicate that γ-irradiation induces negligible chemical changes in the IL phase when it is in contact with a gas phase. For the water-IL systems, the initially immiscible layers slowly developed an interfacial emulsion layer, even in the absence of radiation. This layer started at the water-IL interface and then grew downwards, eventually converting the entire IL phase to an emulsion. Gamma-irradiation accelerated the conversion of the IL phase to an emulsion. The development of the emulsion layer was accompanied by changes in the conductivity and the Raman spectra of both the IL and water phases. Based on these results, a mechanism involving the formation of micelles at, or near, the water-IL interface has been proposed to explain the development of an emulsion layer. We also suggest that radiolytic decomposition of ILs produces surfactants that can accumulate at the interface and, even at low concentrations, accelerate the emulsification process.     

Design of dinuclear copper species with carboranylcarboxylate ligands: study of their steric and electronic effects

A series of new mononuclear and carboranylcarboxylate‐bridged dinuclear copper(II) compounds containing the 1‐CH₃‐2‐CO₂H‐1,2‐closo‐C₂B₁₀H₁₀ carborane ligand ( L H) has been synthesized. Reaction of different copper salts with L H at room temperature leads to dinuclear compounds of the general formula [Cu₂(μ‐ L )₄( L_t )₂] ( L_t =thf ( 1 ), L_t =H₂O ( 1′ )). The reaction of 1 and 1′ with different terminal pyridyl (py) ligands leads to the formation of a series of structurally analogous complexes by substitution of the terminal ligand thf or H₂O ( L_t =py ( 2 ), p‐CF₃‐py ( 3 ), p‐CH₃‐py ( 4 ), pz ( 6 ), and 4,4′‐bpy ( 7 )), which maintain the structural Cu₂(μ‐O₂CR)₄ core in the majority of the cases except for o‐(CH₃)₂‐py, where a mononuclear compound ( 5 ) is exclusively obtained. These compounds have been characterized through analytical, spectroscopic (NMR, IR, UV‐visible, ESI‐MS) and magnetic techniques. X‐ray structural analysis revealed a paddle‐wheel structure for the dinuclear compounds, with a square‐pyramidal geometry around each copper ion and the carboranylcarboxylate ions bridging two copper atoms in syn–syn mode. The mononuclear complex obtained with the o‐(CH₃)₂‐py ligand presents a square‐planar structure, in which the carboranylcarboxylate ligand adopts a monodentate coordination mode. The magnetic properties of the dinuclear compounds 1 , 3 , 4 , and 6 show a strong antiferromagnetic coupling in all cases (J=?261 ( 1 ), ?255 ( 3 ), ?241 ( 4 ), ?249 cm^?1 ( 6 )). Computational studies based on hybrid density functional methods have been used to study the magnetic properties of the complexes and also to evaluate their relative stability on the basis of the strength of the bond between each Cu^II and the terminal ligand.     

Uncommon coordination behaviour of P(S) and P(Se) units when bonded to carboranyl clusters: experimental and computational studies on the oxidation of carboranyl phosphine ligands

Oxidation of closo-carboranyl diphosphines 1,2-(PR(2))(2)-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr) and closo-carboranyl monophosphines 1-PR(2)-2-R'-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr, Cy; R'=Me, Ph) with hydrogen peroxide, sulfur and elemental black selenium evidences the unique capacity of the closo-carborane cluster to produce uncommon or unprecedented P/P(E) (E=S, Se) and P=O/P=S chelating ligands. When H(2)O(2) reacts with 1,2-(PR(2))(2)-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr), they are oxidized to 1,2-(OPR(2))(2)-1,2-closo-C(2)B(10)H(10) (R=Ph, iPr). However, when S and Se are used, different reactivity is found for 1,2-(PPh(2))(2)-1,2-closo-C(2)B(10)H(10) and 1,2-(PiPr(2))(2)-1,2-closo-C(2)B(10)H(10). The reaction with sulfur produces mono- and dioxidation products for R=Ph, whereas Se produces the mono-oxidation product only. For R=iPr, only monooxidation takes place with S, and the second C(c)-PiPr(2) bond breaks to yield 1-SPiPr(2)-1,2-closo-C(2)B(10)H(11). When Se is used, only 1-SePiPr(2)-1,2-closo-C(2)B(10)H(11) is formed. The potential of the mono-chalcogenide carboranyl diphosphines 1-EPPh(2)-2-PPh(2)-1,2-closo-C(2)B(10)H(10) (E=S, 9; Se, 15) to behave as unsymmetric chelating bidentate ligands was studied for different metal complexes, different solvents and in the solid state. Dechalcogenation takes place in each case. Computational studies provided information on the P=E (E=S, Se) bonds. Steric effects block the bonding ability of the P=E group due to interactions between the chalcogen and the neighbouring hydrogen atoms (three from the phenyl rings and one from the carborane cluster). The electronic effects originate from the strongly electron-withdrawing character of the closo carborane cluster, which polarizes the P=E (E=S, Se) bond towards the phosphorus atom. As a consequence, the E atom is the electron-poor site and the P atom the electron-rich site in the P=E bond.     

Approach to the study of C-glycosyl flavones acylated with aliphatic and aromatic acids from Spergularia rubra by high-performance liquid chromatography-photodiode array detection/electrospray ionization multi-stage mass spectrometry

The use of mass spectrometry (MS) coupled to liquid chromatography (LC) as working tool for the study of the C-glycosyl flavones acylated with aliphatic and aromatic acids has allowed the tentative characterization of these compounds in Spergularia rubra and the establishment of the position of the acylation on the sugar moiety of the C-glycosylation by use of MS data. The combination of retention time (Rt), ultraviolet (UV) and MS(n) data of the compounds revealed their C-glycosyl flavone nature, being luteolin, apigenin and chrysoeriol derivatives. Ten non-acylated flavones were identified, from which six are described for the first time (one 7-O-glycosyl-6,8-diC-glycosyl flavone, four 6,8-diC-glycosyl flavones and one 2"-O-glycosyl-6-C-glycosyl flavone). Twenty-six acylated derivatives were also found for the first time. These compounds are grouped in three classes, namely, C-glycosyl flavones acylated with aliphatic acids, with aromatic acids or with a mixed acylation. The first group is characterized by the presence of one 6,8-diC-(acetyl)glycosyl flavone, four 6,8-diC-(malonyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(malonyl)glycosyl flavones, while in the second one twelve 6,8-diC-(acyl)glycosyl flavones and two 7-O-glycosyl-6,8-diC-(acyl)glycosyl flavones are described. The last class contained five 6,8-diC-(malonyl,acyl)glycosyl flavones. No previous work has described the presence of C-glycosyl flavones acylated with aliphatic acids in this genus.     

Determination of 40 currently used pesticides in airborne particulate matter (PM 10) by microwave-assisted extraction and gas chromatography coupled to triple quadrupole mass spectrometry

A confirmatory and sensitive procedure has been developed for the determination of 40 currently used pesticides (CUPs) in airborne particulate matter (PM 10) at trace level. The proposed method includes extraction of PM 10-bound pesticides by microwave-assisted extraction (MAE) followed by a gel permeation chromatography (GPC) clean-up and determination by GC-MS/MS. The injection mode and the main parameters in MS/MS were optimized. The matrix effect was also evaluated. Recoveries ranged from 70 to 120% except for pyrimethanil and pirimicarb. The limit of quantification (LOQ) ranged from 1.32 to 39.47 pg m(-3), when air volumes of 760 m(3) were collected. The method was applied to 38 samples collected from a rural station belonging to the atmospheric monitoring network of the Regional Valencia Government (Spain) during April-June 2010. Eighteen out of 40 pesticides investigated were found in at least one sample (bifenthrin, chlorothalonil, chlorpyriphos-e, chlorpyriphos-m, clorpropham, diazinon, dicofol, diphenylamine, fipronil, fludioxonil, folpet, malathion, metalaxyl, penconazole, quinoxyfen, triadimefon, trifluralin, and vinclozoline), with concentrations ranging from 1.32 to 625.80 pg m(-3).     

Development of an ultra-high performance liquid chromatography analytical methodology for the profiling of olive (Olea europaea L.) pulp proteins

Ultra-high performance liquid chromatography (UHPLC) constitutes an interesting proposal to speed protein separations but it is almost not explored. In this work UHPLC is proposed, for the first time, to separate olive pulp proteins. An important difficulty in the analysis of proteins is related to their extraction. The difficulty in the extraction of proteins from the olive pulp is derived from its high content in lipids and phenolic compounds. Eight different methods for the extraction of pulp proteins were designed and evaluated. The optimized extraction procedure consisted of a cleaning step to remove interfering compounds, followed by the extraction of proteins with a Tris–HCl buffer containing sodium dodecyl sulphate (SDS) and dithiothreitol (DTT), precipitation of proteins with acetone, and solubilization in the Tris–HCl buffer. This methodology yielded the most successful isolation of pulp proteins and enabled the optimization of a UHPLC methodology for their separation. The method was applied to the profiling of olive pulp proteins from different olive cultivars observing in all cases a protein that had never been described before.     

Lesion T(2) relaxation times and volumes predict the response of malignant breast lesions to neoadjuvant chemotherapy

The aim of this study was to investigate the utility of the water T(2) values of malignant breast lesions in predicting response after the first and second cycles of neoadjuvant chemotherapy (NAC), both alone and in combination with lesion volumes. Thirty-five patients were scanned before the commencement of chemotherapy and again after the first, second and final treatment cycles. Two methods of obtaining lesion T(2) were used: imaging, where a series of T(2)-weighted images was acquired (T(R)/T(E)=1000/30, 60, 90 and 120 ms), and spectroscopy, where the T(2) value of unsuppressed water signal was determined with a multiecho sequence (T(R)=1.5 s; initial T(E)=35 ms; 64 steps of 2.5 ms; 2 unsuppressed acquisitions per T(E)). Lesion volumes were computed from contrast-enhanced 3D fat-suppressed images. The study found that, using the imaging method of obtaining T(2), the ratio of the product of lesion T(2) and volume after the second cycle of NAC to pretreatment value is a good predictor of ultimate lesion response, defined as a > or =65% reduction in tumor volume after the final treatment cycle, with positive and negative predictive values of 95.5% and 84.6%, respectively.     

A novel fractional-order model and controller for vibration suppression in flexible smart beam

Nonlinear Dynamics - Vibration suppression represents an important research topic due to the occurrence of this phenomenon in multiple domains of life. In airplane wings, vibration can cause...     

The Contribution of Density Functional Theory to the Atomistic Knowledge of Electrochromic Processes

In this review, we provide a brief overview of the contribution that computational studies can offer to the elucidation of the electronic mechanisms responsible for the electrochromism phenomenon, through the use of the density functional theory (DFT) and its time-dependent formulation (TDDFT). Although computational studies on electrochromic systems are not as numerous as those for other physico-chemical processes, we will show their reliability and ability to predict structures, excitation energies, and redox potentials. The results confirm that these methods not only help in the interpretation of experimental data but can also be used for the rational design of molecules with interesting electrochromic properties to be initiated for synthesis and experimental characterization.     

Synthesis and Pharmacological Characterization of New H2‐Antagonists Containing NO‐Donor Moieties,Endowed with Mixed Antisecretory and Gastroprotective Activities

Synthesis, structural characterization, and pharmacological profile of a series of H₂‐antagonists able to release nitric oxide (NO) are reported. These compounds were obtained by using appropriate spacers to join H₂‐antagonistic pharmacophoric groups related to lamtidine and tiotidine to different NO‐donor moieties such as esters of HNO₃, nitrosothio groups, and benzenesulfonyl‐substituted furoxans. All of the compounds were tested for their NO‐donor properties. Furthermore, the hybrid structures synthesized, together with some selected reference compounds, were tested for their H₂‐antagonistic properties, both in vitro and in vivo, and for their gastroprotective effects. Only the hybrid compounds were able both to antagonize histamine effects on guinea‐pig papillary muscle and to display in vivo antisecretory and gastroprotective action. The best results were obtained with the lamtidine/furoxan hybrid structure.