Distance measures with heavy aggregation operators

The use of distance measures and heavy aggregations in the ordered weighted averaging (OWA) operator is studied. We present the heavy ordered weighted averaging distance (HOWAD) operator. It is a new aggregation operator that provides a parameterized family of aggregation operators between the minimum distance and the total distance operator. Thus, it permits to analyze an aggregation from its usual average (normalized distance) to the sum of all distances available in the aggregation process. We analyze some of its main properties and particular cases such as the normalized Hamming distance, the weighted Hamming distance and the OWA distance (OWAD) operator. This approach is generalized by using quasi-arithmetic means obtaining the quasi-arithmetic HOWAD (Quasi-HOWAD) operator and with norms obtaining the heavy OWA norm (HOWAN). Further extensions to this approach are presented by using moving averages forming the moving HOWAD (HOWMAD) and the moving Quasi-HOWAN (Quasi-HOWMAN) operator. The applicability of the new approach is studied in a decision making model regarding the selection of national policies. We focus on the selection of monetary policies. The key advantage of this approach is that we can consider several sources of information that are independent between them.     

Near-unity quantum yields of biexciton emission from CdSe/CdS nanocrystals measured using single-particle spectroscopy

Biexciton photoluminescence (PL) quantum yields (Q(2X)) of individual CdSe/CdS core-shell nanocrystal quantum dots with various shell thicknesses are derived from independent PL saturation and two-photon correlation measurements. We observe a near-unity Q(2X) for some nanocrystals with an ultrathick 19-monolayer shell. High Q(2X)'s are, however, not universal and vary widely among nominally identical nanocrystals indicating a significant dependence of Q(2X) upon subtle structural differences. Interestingly, our measurements indicate that high Q(2X)'s are not required to achieve complete suppression of PL intensity fluctuations in individual nanocrystals.     

A direct, efficient method for the preparation of siRNAs containing ribo-like North bicyclo[3.1.0]hexane pseudosugars

An efficient method for the preparation of siRNAs modified with ribo-like North bicyclo[3.1.0]hexane pseudosugars is described. The combined use of 2'-O-(2-cyanoethoxymethyl) (CEM) and 2'-O-TBDMS protection was successfully employed for RNA synthesis with the added advantage that both groups were efficiently removed in a single step. The resulting North ribo-methanocarba-modified siRNAs are compatible with the intracellular RNAi machinery and can mediate specific degradation of target mRNA.     

Poly(methyl malate) nanoparticles: formation, degradation, and encapsulation of anticancer drugs

PMLA nanoparticles with diameters of 150-250 nm are prepared, and their hydrolytic degradation is studied under physiological conditions. Degradation occurs by hydrolysis of the side chain methyl ester followed by cleavage of the main-chain ester group with methanol and L-malic acid as the final degradation products. No alteration of the cell viability is found after 1 h of incubation, but toxicity increases significantly after 3 d, probably due to the noxious effect of the released methanol. Anticancer drugs temozolomide and doxorubicin are encapsulated in the NPs with 20-40% efficiency, and their release is monitored using in vitro essays. Temozolomide is fully liberated within several hours, whereas doxorubicin is steadily released from the particles over a period of 1 month.     

Smart thorium and uranium determination exploiting renewable solid-phase extraction applied to environmental samples in a wide concentration range

A smart fully automated system is proposed for determination of thorium and uranium in a wide concentration range, reaching environmental levels. The hyphenation of lab-on-valve (LOV) and multisyringe flow injection analysis (MSFIA), coupled to a long path length liquid waveguide capillary cell, allows the spectrophotometric determination of thorium and uranium in different types of environmental sample matrices achieving high selectivity and sensitivity levels. Online separation and preconcentration of thorium and uranium is carried out by means of Uranium and TEtraValents Actinides resin. The potential of the LOV–MSFIA makes possible the full automation of the system by the in-line regeneration of the column and its combination with a smart methodology is a step forward in automation. After elution, thorium(IV) and uranium(VI) are spectrophotometrically detected after reaction with arsenazo-III. We propose a rapid, inexpensive, and fully automated method to determine thorium(IV) and uranium(VI) in a wide concentration range (0–1,200 and 0–2,000 μg L^-1 Th and U, respectively). Limits of detection reached are 5.9 ηg L^-1 of uranium and 60 ηg L^-1 of thorium. Different water sample matrices (seawater, well water, freshwater, tap water, and mineral water), and a channel sediment reference material which contained thorium and uranium were satisfactorily analyzed with the proposed method.     

Biophysical investigations of GBV-C E1 peptides as potential inhibitors of HIV-1 fusion peptide

Five peptide sequences corresponding to the E1 protein of GBV-C [NCCAPEDIGFCLEGGCLV (P7), APEDIGFCLEGGCLVALG (P8), FCLEGGCLVALGCTICTD (P10), QAGLAVRPGKSAAQLVGE (P18), and AQLVGELGSLYGPLSVSA (P22)] were synthesized because they were capable of interfering with the HIV-1 fusion peptide (HIV-1 FP)-vesicle interaction. In this work the interaction of these peptides with the HIV-1 FP, as well as with membrane models, was analyzed to corroborate their inhibition ability and to understand if the interaction with the fusion peptide takes place in solution or at the membrane level. Several studies were carried out on aggregation and membrane fusion, surface Plasmon resonance, and conformational analysis by circular dichroism. Moreover, in vitro toxicity assays, including cytotoxicity studies in 3T3 fibroblasts and hemolysis assays in human red blood cells, were performed to evaluate if these peptides could be potentially used in anti-HIV-1 therapy. Results show that P10 is not capable of inhibiting membrane fusion caused by HIV-1 and it aggregates liposomes and fuses membranes, thus we decided to discard it for futures studies. P18 and P22 do not inhibit membrane fusion, but they inhibit the ability of HIV-1 FP to form pores in bilayers, thus we have not discarded them yet. P7 and P8 were selected as the best candidates for future studies because they are capable of inhibiting membrane fusion and the interaction of HIV-1 FP with bilayers. Therefore, these peptides could be potentially used in future anti-HIV-1 research.     

A smart palladium catalyst in ionic liquid for tandem processes

New catalytic systems based on in situ and preformed palladium nanoparticles in ionic liquids (characterised by TEM) starting from palladium acetate or dipalladiumtris(dibenzylideneacetone) have been applied in the synthesis of 4-phenylbutan-2-one (II), a model compound for the preparation of fragrances. Imidazolium-based ionic liquid containing a methyl hydrogenophosphonate anion leads to an efficient Pd-catalyzed tandem coupling/reduction process, taking advantage of the multi-role of this solvent (nanoparticles stabiliser, base, hydrogen transfer agent). The influence of the mono-phosphine ligands (1-3) on the catalyst has been evaluated, showing that the ligand-free palladium system turns into the most appropriate for the formation of II using Pd(OAc)(2) as precursor. Fine-tuning conditions involved in this multi-parameter process have led us to propose a plausible mechanism based on the hydrogen transfer coming from the methyl hydrogenophosphonate anion.     

A New Modular Phosphite‐Pyridine Ligand Library for Asymmetric Pd‐Catalyzed Allylic Substitution Reactions: A Study of the Key Pd‐π‐Allyl Intermediates

A library of phosphite‐pyridine ligands L1 – L12 a – g has been successfully applied for the first time in the Pd‐catalyzed allylic substitution reactions of several di‐ and trisubstituted substrates by using a wide range of C, N and O nucleophiles, among which are the little studied α‐substituted malonates, β‐diketones, and alkyl alcohols. The highly modular nature of this ligand library enables the substituents/configuration at the ligand backbone, and the substituents/configurations at the biaryl phosphite moiety to be easily and systematically varied. We found that the introduction of an enantiopure biaryl phosphite moiety played an essential role in increasing the versatility of the Pd‐catalytic systems. Enantioselectivities were therefore high for several hindered and unhindered di‐ and trisubstituted substrates by using a wide range of C, N and O nucleophiles. Of particular note were the high enantioselectivities (up to>99 % ee) and high activities obtained for the trisubstituted substrates S6 and S7 , which compare favorably with the best that have been reported in the literature. We have also extended the use of these new catalytic systems in alternative environmentally friendly solvents such as propylene carbonate and ionic liquids. Studies on the Pd‐π‐allyl intermediates provide a deeper understanding of the effect of ligand parameters on the origin of enantioselectivity.