Ordinary p-Laplacian systems with nonlinear boundary conditions

This paper is concerned with the existence of solutions for the boundary value problem

     

Synthesis of (R)-2-(benzyloxy)-tetrahydro-5,5-dimethylfuran by a new oxidative rearrangement

The rearrangement under oxidative conditions of 3-(benzyloxy)-tetrahydro- 2,6,6-trimethyl-2H-pyran-2-carbaldehydes to afford a chiral protected tetrahydrofuran lactol is described.     

Towards a Living Radical Polymerization of Styrene by Using Dithiolactone as a New Type of Mediating Agent

In this communication, γ‐phenyl‐γ‐butyrodithiolactone (DTL1) is presented as the first example of a new type of control agent. The styrene polymerization carried out at 60 °C in the presence of DTL1 exhibits living characteristics, without consuming DTL1 during the process. This unprecedented behavior was explained by a mechanism based on the reversible formation of a persistent radical adduct between the DTL1 and the polystyrene macroradicals.

     

A characterization study of xerogel silicapropylaniline powders

Silicapropylaniline nanometric materials with varying organic content were obtained using a sol-gel synthesis. By increasing the organic load, the scanning electron microscopy technique shows a slight increase in the average size of aggregated particles. N₂ isotherms and positron annihilation lifetime spectroscopy measurements show that the average pore size decreases accompanied by a surface area reduction. FTIR thermal analysis was used to estimate the thermal stability of the organic phase and also to detect the presence of trapped organic groups in closed pores. From the organic coverage and surface area measurements the surface density of the immobilized organic molecules as well as the average intermolecular distance between them could be estimated.     

Fatty acid composition and volatile compounds of caviar from farmed white sturgeon (Acipenser transmontanus)

The present study was conducted to characterize caviar obtained from farmed white sturgeons (Acipenser transmontanus) subjected to different dietary treatments. Twenty caviar samples from fish fed two experimental diets containing different dietary lipid sources have been analysed for chemical composition, fatty acids and flavour volatile compounds. Fatty acid make up of caviar was only minimally influenced by dietary fatty acid composition. Irrespective of dietary treatments, palmitic acid (16:0) and oleic acid (OA, 18:1 n-9) were the most abundant fatty acid followed by docosahexaenoic acid (DHA, 22:6 n-3) and eicopentaenoic (EPA, 20:5 n-3). Thirty-three volatile compounds were isolated using simultaneous distillation-extraction (SDE) and identified by GC-MS. The largest group of volatiles were represented by aldehydes with 20 compounds, representing the 60% of the total volatiles. n-Alkanals, 2-alkenals and 2,4-alkadienals are largely the main responsible for a wide range of flavours in caviar from farmed white surgeon.     

New findings for in-gel digestion accelerated by high-intensity focused ultrasound for protein identification by matrix-assisted laser desorption ionization time-of-flight mass spectrometry

New findings in sample treatment based on high-intensity focused ultrasound (HIFU) for protein digestion after polyacrylamide gel electrophoresis separation are presented. The following variables were studied: (i) sample volume; (ii) sonotrode diameter; (iii) previous protein denaturation; (iv) cooling; (v) enzyme concentration; and (vi) protein concentration. Results showed that positive protein identification could be done after protein separation by gel electrophoresis through peptide mass fingerprint (PMF) in a volume as low as 25 microL. The time needed was less than 2 min and no cooling was necessary. The importance of the sonotrode diameter was negligible. On the other hand, protein denaturation before sonication was a trade-off for the success of procedure here described. The protein coverage was raised from 5 to 30%, and the number of peptides matching the proteins was also increased in a percentage ranging 10-100% when the classical overnight treatment is compared with the proposed HIFU procedure. The minimum amount of protein that can be identified using the HIFU sample treatment by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was 0.06 microg. The lower concentration of trypsin successfully used to obtain an adequate protein digestion was 3.6 microg/mL.     

2-Methylisoxazolin-5-ones III. Curboxylic. Acids and their Derivatives

Carbethoxy-substituted 12-methylisoxazolin-5-ones and several functional derivatives have been prepared. Spectral properties of the corresponding carboxylic acids are discussed. These acids ant stronger when the carboxy group is in position 3 than when in position 4 of the heterocycle.     

Numerical stability analysis of submerged slopes subject to rapid sedimentation processes

In this paper, the stability of infinitely long submerged slopes subject to rapid sedimentation processes is theoretically/numerically investigated. In particular, rapid deposition is considered as a potential triggering factor for static liquefaction in inclined loose sand layers. The corresponding initial boundary value problem is numerically analysed by employing a one-dimensional finite difference scheme in conjunction with two distinct versions of the same constitutive model—elasto-plastic and elasto-viscoplastic (EV). The EV approach is shown to be the most suitable for describing the onset of liquefaction phenomena, since its mathematical well-posedness and numerical stability are never lost. The results of parametric analyses for both homogeneous and inhomogeneous strata are critically discussed in the light of some case history data concerning natural and anthropic sedimentation processes.     

A microcalorimetric enzymatic method for trehalose determination in food

As trehalose is a glucose font and also an additive in food, a new reliable method for trehalose determination is proposed. The analytical method uses an isothermal microcalorimeter, directly relates the analyte concentration with the heat variation of the enzymatic decomposition of trehalose into two glucose molecules. The enzymatic reaction is performed inside the calorimeter in the presence of trehalase enzyme immobilized on amino activated glass beads. Through the calibration curve, the trehalose quantity in some food samples (mushrooms and honey) has been determined. The calorimetric procedure was compared to a previously identified methodology based on an amperometric biosensor.