Pt on SAS-CeO2 nanopowder as catalyst for the CO-WGS reaction

In this paper, we present a study on the preparation of ceria nanopowder by Supercritical Antisolvent technique and its use as catalysts support for water gas shift reaction. The effect of the concentration of ceria precursor and the solution flow rate was evaluated on particle size and granulometric distribution. The increase of concentration led to an increase in the average particle size, whereas the solution flow rate had a negligible effect. The platinum/ceria catalyst was prepared by wet impregnation and fully characterized; SEM and TEM-EDX showed a mean particle size of around 50 nm and a good dispersion of the active component. The results of the activity tests highlighted a good performance of the SAS-derived catalyst, that showed higher CO conversion with respect to a catalyst obtained from commercial ceria nanopowder.     

Lonicera Implexa Leaves Bearing Naturally Laid Eggs of the Specialist Herbivore Euphydryas Aurinia have Dramatically Greater Concentrations of Iridoid Glycosides than other Leaves

We tested in the field the hypothesis that the specialist butterfly Euphydryas aurinia (Lepidoptera: Nymphalidae, Melitaeinae) lays eggs on leaves of Lonicera implexa (Caprifoliaceae) plants with greater iridoid concentrations. We conducted our investigations in a Mediterranean site by analyzing leaves with and without naturally laid egg clusters. There were no significant differences in iridoid glycoside concentrations between leaves from plants that did not receive eggs and the unused leaves from plants receiving eggs, a fact that would seem to indicate that E. aurinia butterflies do not choose plants for oviposition by their iridoid content. However, the leaves of L. implexa that bore egg clusters had dramatically greater (over 15-fold) concentrations of iridoid glycosides than the directly opposite leaves on the same plant. These huge foliar concentrations of iridoids (15% leaf dry weight) may provide specialist herbivores with compounds that they either sequester for their own defense or use as a means of avoiding competition for food from generalist herbivores. Nevertheless, it may still be possible that these high concentrations are detrimental to the herbivore, even if the herbivore is a specialist feeder on the plant.     

Effect of flour type on Maillard reaction and acrylamide formation during toasting of bread crisp model systems and mitigation strategies

Maillard reaction along with caramelisation are the main chemical reactions occurring in bakery products. They are referred to as non enzymatic browning. In this work, the effect of flour type (wheat, rye and whole-wheat flours) and process conditions were investigated by using a bread crisp model system made up of flour, water and yeast. The bread was toasted at different temperature for different times. In a second set of experiments several additives (glycine, 0.1% on flour; asparaginase, 2000 U kg⁻¹ of flour and an antioxidant extract from green tea) were added to the basic formulations in order to test their ability in reducing the formation of potentially harmful Maillard reaction compounds such as HMF and acrylamide. Browning development and water content along with antioxidant activity were also monitored.Rye model systems produced more HMF and acrylamide at all temperature tested, while wholewheat systems produced less HMF, but more acrylamide than wheat one. The addition of glycine was effective in reducing acrylamide formation, and it increased browning development, antioxidant activity and HMF formation. Asparaginase reduced acrylamide formation up to 88% and had no effect on browning development and antioxidant activity. The addition of exogenous antioxidant compounds from green tea did not produce clear effect on acrylamide formation, thus it was not useful as mitigation strategy in bakery products, likely because of the low fat content.     

Supercritical antisolvent precipitation of Cephalosporins

We successfully performed the micronization of some Cephalosporinic antibiotics by Supercritical AntiSolvent (SAS) precipitation from Dimethylsulfoxide (DMSO) and evaluated the effect of temperature, pressure, concentration of the liquid solution and carbon dioxide molar fraction on the precipitation process. In particular, we varied temperature from 40 to 60 °C, pressure from 90 to 180 bar, concentration of the liquid solution from 10 to 90 mg/mL and CO₂ molar fraction from 0.5 to 0.98.We obtained different morphologies of precipitates: sub-microparticles, microparticles, balloons (micrometric empty shells) and large crystals. We tried to explain how the presence of solute modifies the vapor-liquid equilibria (VLEs) of the system DMSO-CO₂ and to relate the different morphologies observed to the position of the process operating point with respect to the ternary system mixture critical point (MCP). Particle dimensions range from 0.1 to 14 μm for spherical particles and from 3 to 50 μm for balloons.     

The role of radiolabeled somatostatin analogs in adrenal imaging

A retrospective epidemiological survey was conducted to evaluate the incidence and characteristics of thrombocytopenic purpura (TP) reported in France following measles, mumps or rubella vaccination with monovalent or multivalent vaccines. Sixty cases of TP were reported i.e an incidence/100,000 doses of 0.23 and 0.17 for measles or rubella vaccines respectively given alone, to 0.87 for combined measles-rubella vaccine and 0.95 for MMR vaccine. The mean age was 21 +/- 12 months and the delay of diagnosis was 16 +/- 6 days after vaccination. Thrombopenia was severe (mean platelet count: 8000 +/- 6000/mm3) and always associated with purpura. The immediate outcome was favourable in 89.5 per cent of cases. Vaccine-associated TP appears to be similar to acute childhood idiopathic thrombocytopenic purpura but the clear temporal relationship between MMR vaccination and the occurrence of TP make a causal relationship highly plausible. Acute TP seems a rare complication of measles-rubella and MMR vaccination but clinicians had to be informed of the possibility of their occurrence. Acute TP following vaccination should be reported by physicians to their Regional Drug Surveillance Centre.     

A cross-cultural study of the psychometric properties of the Reactive–Proactive Aggression Questionnaire among Italian nonclinical adolescents.

Five independent studies were used to test the hypothesis that a reliable 2-factor structure underlies the Reactive–Proactive Aggression Questionnaire (RPQ) items and that the 2 scales show distinct patterns of association with personality and bullying behavior measures. Study 1 (N = 1,447) gave evidence of a clear 2-factor structure of RPQ items with factor loading matrices closely matching reactive (congruence coefficient = .90) and proactive (congruence coefficient = .91) models of item assignment. The RPQ 2-factor structure was consistently replicated in Study 2 (N = 662), as well as across the remaining 3 studies. In Study 3 (N = 536), Neuroticism differentiated reactive and proactive forms of aggression. In Study 4 (N = 674), self-reports of bullying behaviors were selectively correlated with proactive aggression. Findings confirm and extend the differential correlates of proactive–reactive aggression and also support the psychometric properties of the RPQ in a different cultural context. Finally, in Study 5 (N = 347), the RPQ scales showed adequate 2-month test–retest reliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of pressure, temperature and concentration on the mechanisms of particle precipitation in supercritical antisolvent micronization

In this work, supercritical antisolvent micronization (SAS) is used to produce nanoparticles, microparticles and expanded microparticles of a model compound, gadolinium acetate (GdAc), using dimethylsulfoxide (DMSO) as the liquid solvent with the aim of studying the dependence of particles’ diameter and morphology on some process parameters like pressure, temperature and concentration of the starting solution. Experiments are performed varying the precipitation pressure between 90 and 200 bar, the precipitation temperature between 35 and 60 °C and the concentration of GdAc in the liquid solution in the range from 20 to 300 mg/mL. The experimental evidences show that the formation of particles with specific sizes in the micrometric and nanometric range depends on specific values of each one of these parameters. An explanation of the results is proposed in terms of the competition between two characteristic times of the SAS process that can control the precipitation process. The time of jet break-up of the liquid solution that produces liquid droplet formation, and the dynamic surface tension vanishing time, that induces gas mixing with the precipitation of nanoparticles from the gaseous phase. Indeed, GdAc sub-microparticle, or microparticle (diameter in the range 0.23-1.6 μm with mean diameters in the range 0.28-0.52 μm) formation can be attributed to micro-droplet drying, whereas nanoparticles (mean diameter in the range 90-210 nm) are consistently produced when gas mixing is the possible governing process. In conclusion, the precipitation mechanisms can be modulated varying one SAS parameter a time, thus selecting the range of particle diameters required for the specific application.     

Synthesis and properties of block poly(ether‐ester)s based on poly(ethylene oxide) and various hydrophobic segments

To obtain biodegradable amphiphilic block polymers for biomedical applications, a series of poly(ether‐ester)s based on poly(ethylene oxide) and various hydrophobic/hydrophilic segment ratios were synthesized by the solution polymerization technique. The polyesters were characterized using ¹H NMR spectroscopy, elemental analysis, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis and compression stress–strain measurements. The composition of the poly(ether‐ester)s agreed with the feed ratio. A study of the degree of phase segregation in the polymers evidenced that microphase mixing increases with the presence in the hydrophobic segments of polar groups able to establish interactions with the poly(ethylene oxide). This phase mixing increased the thermal stability of the acidic poly(ether‐ester)s. Nanospheres for drug delivery with an average diameter of 50 nm were obtained by employing the acidic poly(ether‐ester) showing less microphase segregation, while a scaffold structure with a homogeneous and highly interconnected porosity and an average pore size of approximately 15 µm for tissue engineering was prepared using the more hydrophobic copolymer not possessing functional groups. Compression mechanical measurements carried out on the scaffold showed that the more hydrophobic copolymer was suitable for tissue engineering applications. In order to obtain polymers employable both in drug delivery and in tissue engineering a series of block poly(ether‐ester)s showing various phase segregations were synthesized by varying the hydrophobic/hydrophilic segment ratio. Copyright © 2010 Society of Chemical Industry