PVDF-based composites containing PZT particles: How processing affects the final properties

Poly(vinylidene fluoride) (PVDF)-based composites containing up to 30 vol % of lead zirconate titanate (PZT) particles were prepared by: (a) different techniques, melt blending and solvent casting; and (b) different molding procedures, a single-step and a two-step hot-pressing method. The obtained samples were characterized in order to study how the processing affects their final properties. Results indicate that the different molding processes have a strong effect on polymorphism and molecular relaxations of PVDF as well as on dielectric response of the composite materials, that results enhanced by the two-step molding. The preparation technique influences the filler dispersion and, consequently, the elastic modulus of the composites, but without remarkably impacting on other properties. This suggests the possibility of preparing performing composites by a solvent-free and easily scalable technique (i.e., melt blending) and obtaining suitable dielectric characteristics, very important for application of such kind of materials, just by tuning the molding conditions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48871.     

SNPs of the FADS Gene Cluster are Associated with Polyunsaturated Fatty Acids in a Cohort of Patients with Cardiovascular Disease

Polymorphisms of the human Δ-5 (FADS1) and Δ-6 (FADS2) desaturase genes have been recently described to be associated with the level of several long-chain n-3 and n-6 polyunsaturated fatty acids (PUFAs) in serum phospholipids. We have genotyped 13 single nucleotide polymorphisms (SNPs) located on the FADS1–FADS2–FADS3 gene cluster (chromosome 11q12–13.1) in 658 Italian adults (78% males; mean age 59.7 ± 11.1 years) participating in the Verona Heart Project. Polymorphisms and statistically inferred haplotypes showed a strong association with arachidonic acid (C20:4n-6) levels in serum phospholipids and in erythrocyte cell membranes (rs174545 adjusted P value for multiple tests, P < 0.0001 and P < 0.0001, respectively). Other significant associations were observed for linoleic (C18:2n-6), alpha-linolenic (C18:3n-3) and eicosadienoic (C20:2n-6) acids. Minor allele homozygotes and heterozygotes were associated to higher levels of linoleic, alpha-linolenic, eicosadienoic and lower levels of arachidonic acid. No significant association was observed for stearidonic (C18:4n-3), eicosapentaenoic (C20:5n-3) and docosahexaenoic (C22:6n-3) acids levels. The observed strong association of FADS gene polymorphisms with the levels of arachidonic acid, which is a precursor of molecules involved in inflammation and immunity processes, suggests that SNPs of the FADS1 and FADS2 gene region are worth studying in diseases related to inflammatory conditions or alterations in the concentration of PUFAs. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Daily Dialysis: Toward a New Standard in Well‐Being

Daily hemodialysis (DHD) is a promising option; however, logistic obstacles and clinical perplexities limit its dissemination. Understanding the mechanisms of, and the time until, the onset of improved well‐being may help to quantify clinical advantages and to define the minimum length of a “trial” of daily dialysis. By following 30 patients treated in 4 centers, this study aimed to determine how long a period of time is needed until a patient experiences subjective improvement. From November 1998 to November 2000, 30 patients tried at least 2 weeks of short daily dialysis in four Northern Italian centers of Piemonte and Valle d'Aosta. The DHD (2 – 3 hours; blood flow 270 – 350 mL/min; individual HCO₃, Na, K) was performed at home or in a center. Motivations to try DHD, fears and concerns regarding DHD, and changes in perceived well‐being were assessed by semi‐structured interview. The main clinical indications for a trial of DHD were poor tolerance of conventional treatment, cardiovascular disease, and hypertension or hypotension; only 6 patients had no comorbidity at start. The patients' main reasons for choosing DHD were related to job problems and the search for a better treatment. Most of the patients continued DHD because of improved well‐being; logistic reasons accounted for the drop‐outs (5 patients). The main fears were related to logistic aspects, vascular access problems, and excessive involvement of the partner on home dialysis. Improved well‐being was reported by 28 of 30 patients; 2 patients reported no difference. Subjective improvement was perceived within 2 weeks in 22 of 30 patients, and within 1 month in 28 of 30 patients. An offer of a 2 – 4 week trial of DHD may help patients and caregivers to determine whether subjective and objective benefits outweigh logistic problems and whether a permanent transfer to DHD is worthwhile.     

HPLC assay of ascorbic acid in fresh and processed fruit and vegetables

A method is reported to estimate ascorbic acid (AA) content in fresh and preserved fruit and vegetables. Following its extraction by HPO₃, AA is separated by HPLC on a strong anionic pellicular (Partisil 10 SAX) column, isocratically eluting with 0·1 m sodium acetate buffer solution at pH 4·25, and detecting at 250 nm by a variable wavelength UV detector. The amount of AA is estimated by adding benzoic acid as an internal standard and processing data by an attached electronic printer plotter integrator.The method has shown a high selectivity and speed together with a very good reliability in the range 0·04% to 1% AA.     

Enzyme immobilisation within insolubilised gelatin

A method originally developed for entrapping invertase-active yeast cells (Saccharomyces cerevisiae) in gelatin has been extended to enzymes. Six enzymes belonging to three different classes were immobilised in gelatin made insoluble by formaldehyde. The activity yield of the resulting immobilised enzyme preparations ranged from 9.6 to 48.0%. These values, however, can be roughly doubled by crushing the immobilised enzyme particles into very small fragments, thus indicating that independently of enzyme sensitivity to formaldehyde or of enzyme interaction with gelatin, the limiting factor is mass transfer resistance to diffusion of substrate into the insolubilised gelatin matrix.     

Empirical Identification in the Mixed Logit Model: Analysing the Effect of Data Richness

The flexible structure of the mixed logit (ML) model is at the root of the difficulties associated to its estimation. Major problems are parameter identification and the distinction between different substitution patterns. In this paper we focus on the empirical identification problem and investigate the effect of low information richness in the data on the capability of estimating a correct ML model (i.e. with identifiable parameters and free of confounding effects). In particular, we analyse to which extent the empirical identification problem depends on the variability of the data among alternatives, on the degree of heterogeneity of the taste parameters, on the dimension of the sample and on the number of choice tasks for each individual. To test for information richness of the data and its effect on the capability of the ML model to reproduce random heterogeneity in tastes, a collection of datasets was generated varying systematically (a) the standard deviation (SD) of the distribution of travel time differences between the two alternatives, (b) the SD of the random parameter, (c) the number of choice tasks for each individual and (d) the number of individuals in relation to the number of choice tasks. Then, several ML models allowing for random travel time parameters were estimated using different number of draws and results were compared in terms of model goodness of fit and, also, on the capability of reproducing the real parameters used to generate each dataset. Our results suggest that identification problems depend only on the (low) variability of the associated data and disappear as the richness of the data associated to the random parameter increases. However, rich enough data only allows obtaining good statistics but the estimated parameters do not always reproduce the correct values, as the capability of the ML to reproduce random heterogeneity depends on the random parameter distribution (degree of variability and symmetry). Moreover, the capability of the ML to reproduce random heterogeneity increases when more than one choice is available for each individual and the effect of sample size on the empirical identification reduces considerably.     

Mapping the 5-50-kDa fraction of human amniotic fluid proteins by 2-DE and ESI-MS

This report presents a proteomic analysis and provides a reference map of the 5-50-kDa components of normal amniotic fluid collected in gestational weeks 16-18. Early amniocentesis samples were pooled and proteins with molecular mass lower than albumin were separated by gel filtration chromatography. The 2-DE protocol was optimized for the separation of the small proteins and peptides in the fraction of interest. A total of 132 Coomassie blue-stained protein spots were analyzed, following in-gel tryptic digestion, by ESI-MS/MS and 49 different gene products were identified. The treatment with alkaline phosphatase caused the shift of the phosphoisoforms of insulin-like growth factor-binding protein-1 and of the N-terminal osteopontin fragment. Of the 33 full-length proteins identified in the 2-DE profile, 23 had not been previously detected in the amniotic fluid and, of these, 22 are not present in the human plasma proteome under physiological conditions. Fragments of 16 larger proteins were identified and the sequence coverage data revealed that several correspond to autonomous domains that may have biological roles on their own. Several of the detected proteins and peptides appear to be involved in critical regulatory processes associated with placentation and early development, thus representing potential markers of various physiological or pathological conditions.