Nanoparticles from polylactide and polyether block copolymers: formation, properties, encapsulation, and release of pyrene--fluorescent model of hydrophobic drug

Polylactide-b-polyglycidol-b-poly(ethylene oxide) terpolymers and their derivatives with carboxyl and 4-(phenylazo)phenyl labels in polyglycidol blocks were used for formation of nanoparticles. Nanoparticles were produced by self assembly of terpolymer macromolecules in water above the critical aggregation concentration and by dialysis of terpolymer solutions in 1,4-dioxane against water. For terpolymers with 4-(phenylazo)phenyl labels critical aggregation concentrations increased after irradiation with UV light (300 < lambda < 400 nm) inducing conformational change of the label from trans- to cis-conformation. Diameters of nanoparticles obtained by self-assembly of macromolecules ranged from 20 to 44 nm. Dialysis yielded nanoparticles with bimodal diameter distribution. One fraction had diameters below 35 nm and diameters of the second fraction were in a range from 350 to 2300 nm, depending on terpolymer structure. Mixtures of terpolymers with poly(L,L-lactide) and poly(D,D-lactide) blocks yielded nanoparticles with diameters from 350 to 440 nm. Pyrene was incorporated into nanoparticles by partition between solution and nanoparticles or directly during particle formation by dialysis. Monitoring of pyrene release from nanoparticles suggests that a fraction of this compound was entrapped into the polylactide core whereas the remaining one was located in the polyether rich shell. The release from shells is faster for nanoparticles made from copolymers with carboxyl labels in polyglycidol blocks.     

Columnar Fe2O3 arrays via plasma-enhanced growth: Interplay of fluorine substitution and photoelectrochemical properties

A single-step plasma enhanced-chemical vapor deposition (PE-CVD) route for the synthesis of F-doped iron(III) oxide nanomaterials is presented. Growth experiments, performed from a fluorinated Fe(II) β-diketonate precursor on Indium Tin Oxide (ITO) between 200 and 400 °C, yielded columnar β-Fe₂O₃ arrays with a preferential (100) growth direction. The fluorine content in the deposits could be adjusted by the sole variation of the deposition temperature controlling, in turn, the optical absorption and energy bandgap. Photocurrent measurements and Mott–Schottky analyses, carried out in Na₂SO₄ solution under one sun illumination, evidenced a conductivity switch from n- to p-type upon increasing fluorine amount in the obtained nanomaterials. The sample photocurrent density, donor content and flatband potential support the hypothesis that a progressive substitution of oxygen by fluorine in the iron(III) oxide lattice can alter electronic structure and extend charge carrier lifetimes, making anion-doped β-Fe₂O₃ an efficient water oxidation catalyst.     

An empirical approach to compare the performance of heterogeneous academic fields

In this paper, we propose a ‘scaling’ approach to compare the scientific performance of Italian heterogeneous academic disciplines. This method is based on the idea that, after eliminating the percentages of ‘silent’ researchers, the distribution of bibliometric parameters of the different academic fields can be superimposed and collapse into a unique master curve by a single scaling parameter. By using data on the scientific production of around 2,500 scholars of the university of Rome ‘La Sapienza’ from the Web of Science from 2004 to 2008, we (i) demonstrate the existence of a master curve, (ii) determine the scaling factors that work like rates of substitution to compare the scientific production across different academic fields on a common ground, (iii) show that the master bibliometric distribution follows a log-normal law and (iv) illustrate the relevance of the proposed approach for research assessment and allocation of competitive funding at the university level.     

Washcoating of low surface area cerium oxide on complex geometry substrates

ABSTRACT

An acid-free formulation based on water, glycerol, and polyvinyl alcohol (PVA) was studied to disperse and stabilize, via steric-like interaction, low surface area cerium oxide powders. A dispersion route that implies a milling process and a proper ratio among the components was experienced. PVA was used as viscosity modulator, to enhance viscosity and system stability. Newtonian fluids, suitable for foams dip-coating, were obtained in the application shear range. Foams with different porosities (20, 30, and 40 pore per inch density) were coated. It was found that withdrawal velocity did not affect deposition: a constancy in coating load was obtained once rheology was fixed, while multiple dipping was effective to enhance load. An optimal flash drying temperature (350°C) was identified to consolidate the coated layer and to decompose the organic additives. Good loads, homogeneous coverage, and no pore clogging were obtained after calcination at 900°C. Even though acceptable weight losses were obtained, further investigations need to be accomplished to understand data scattering after adhesion tests.     

Validation by a Collaborative Interlaboratory Study of an ELISA Method for the Detection of Caseinate Used as a Fining Agent in Wine

The clarification or fining of wine removes undesirable substances such as proteins, phenols, and tannin compounds that would cloud the wine and cause bitterness and astringency. Caseinates have useful fining properties, but their residues could present a risk for allergic subjects. A commercial kit that was developed to detect caseinates in food has been examined for its applicability to a wine matrix; it is sensitive to caseinates at concentrations as low as 1 ppm. The general characteristics of the caseinate assay, described below in detail, are as follows. It is a sandwich enzyme-linked immunosorbent assay (ELISA): the microplate is first coated with a specific anti-casein antibody; and after incubation with the wine sample, a secondary anti-casein antibody conjugated with horseradish peroxidase is added to form a sandwich. The antibodies have been tested for their immunoreactivity and the reproducibility of antigen recognition has been measured. An interlaboratory collaborative trial was organized to evaluate the performance of this ELISA method and its ease of use by laboratories routinely dealing with wine/food analyses. The results satisfy the criteria established by the International Organisation of Vine and Wine in the Compendium of International Methods of Analysis MA-EAS1-07-ETCOL.     

Absence of allergenic residues in experimental and commercial wines fined with caseinates

The possible presence of allergenic residues in wines treated with one of the potassium caseinates used as fining agents has been investigated.     

Role of anionic and nonionic surfactants on the control of particle size and latex colloidal stability in the seeded emulsion polymerization of butyl methacrylate

The evolution of the main colloidal parameters in the seeded starved‐feed semi‐continuous emulsion polymerization of butyl methacrylate (BMA) was investigated, with the main purpose of assessing the effectiveness of the semi‐empirical relationship S = K · S_S · ΔA/A_S as a tool to define the surfactant/monomer feed ratio (∝ K) best suited to achieve a target particle size. In particular, the effect of the type and amount of surfactant [i.e., anionic, sodium dodecyl sulfate (SDS), or nonionic, Brij 58P] added during the semi‐continuous stage was considered. Coagulum formation was never observed under the adopted experimental conditions. To detect the occurrence of secondary nucleation or particle aggregation, or both, the particle size and number of particles, the surface tension and the particle surface coverage ratio were correlated. The best results were obtained with SDS and 0.8 ≤ K ≤ 3. In fact, under the selected experimental conditions, only with SDS did the number of particles remain nearly constant throughout the polymerization at the value defined by the seed latex; the particle size distribution was highly monodisperse, and the final particle diameter closely matched the calculated one (～ 120 nm). The above semi‐empirical relationship based on the adjustable parameter K was validated by running test polymerizations aimed at lattices with well‐defined particle size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3083–3094, 2006     

A Petri nets semantics for data flow networks

This work presents a truly concurrent operational semantics for nondeterministic data flow networks. We introduce a model, the df-process, which is a notion similar to that of non-sequential process for a Petri net: a df-process is defined as a mapping from an occurrence net K to a data flow net N, such that the places and the transitions of K are mapped onto the channels and the nodes of N. A df-process contains, by means of some labelling of the places, information on the value and the order in which data flow through the channels during a computation. Df-processes for a data flow network are characterized in an abstract way by a set of properties and in general a df-process corresponds to a set of computations of the network. We give a way to build the df-process corresponding to a computation incrementally at each event occurrence: a main result of the paper is that the incremental construction yields exactly the same set of df-processes as abstractly defined. We also show that df-processes are compositional. The model is intended to be used by distributed systems designers: it contains enough information to be a guideline for the designer and to be a base to develop dynamic checking tools. We outline how df-processes can be used in the design phase of a system.Research supported in part by Progetto Coordinato CNR ANATRA     

A dirichlet process elaboration diagnostic for binomial goodness of fit

Useful model checking tools can be constructed by measuring the distance between a prior distribution that concentrates most of its mass around a model of interest, and the resulting posterior distribution. In this paper we use this approach to construct a diagnostic measure for detecting lack of fit in discrete data, with special focus on binomial data. We begin by constructing a suitable probability model “around” the model of interest, via a Dirichlet Process elaboration. We derive the resulting diagnostic and show that, approximately, it is the sum of two terms: the first is the logarithm of the Bayes factor and the second is proportional to the Pearson chi-square statistics. We give details of a simulation algorithm for computing the diagnostic and illustrate its use in an application to biomedical data.