Effects of SiO2 and Al2O3 nanofillers on polyethylene properties

Polymers filled with inorganic nanoparticles have become interesting materials as dielectrics because of their improved mechanical and electrical properties compared with the unfilled polymers and with polymer microcomposites. These improvements are mainly due to the large surface area of nanoparticles and new polymer–nanofiller interface characteristics. In the present work, polyethylene nanocomposites with SiO₂ and Al₂O₃ nanoparticles were prepared by melt mixing. Mechanical and electrical properties of these composites were determined and morphological aspects were revealed by scanning electron microscopy, wide‐angle X‐ray diffraction, and atomic force microscopy. The effect of nanostructure and the importance of nanofiller dispersion were analyzed in connection with mechanical and electrical properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

In Situ Ultrasonic Characterization of Cocoa Butter Using a Chirp

Differences between tempered and untempered cocoa butter were investigated by an ultrasonic signal “chirp” generated by contact transducers. Polarized light microscopy and powder X-ray diffraction were used to characterize the morphology and polymorphism of tempered and untempered cocoa butter, whereas pulsed nuclear magnetic resonance was used to determine the amount of crystalline solids present. Ultrasonic wave velocity and attenuation data were collected simultaneously throughout the 5-h crystallization process for cocoa butter. Ultrasonic velocity and attenuation changed at the different solid fat contents (SFC): 4, 8, and 11 %. Untempered cocoa butter showed an attenuation of 3 dB/cm at 1.7 MHz and 4 % SFC, whereas tempered cocoa butter showed an attenuation of 4.5 dB/cm at 1.7 MHz and 4 % SFC. At 3 MHz, the attenuation was 2 dB/cm for untempered and 6 dB/cm for tempered cocoa butter. Under these conditions (4 % SFC, 3 MHz), the chirp wave of tempered sample showed a phase angle change of 0.5 rad, whereas the untempered sample showed ?0.5 rad relative to the canola oil that was taken as 0. The study suggests that an ultrasonic chirp can be effectively used to detect differences between tempered and untempered cocoa butter when measuring attenuation and ultrasonic wave phase angle changes as a function of frequency. The in-line characterization of chocolate “temper” using such nondestructive ultrasonic measurements could be applied to industrial chocolate manufacturing.     

Polymerase Synthesis of DNAs Bearing Vinyl Groups in the Major Groove and their Cleavage by Restriction Endonucleases

DNA molecules containing 5‐vinyluracil, 5‐vinylcytosine, or 7‐deaza‐7‐vinyladenine were prepared by polymerase incorporation of the corresponding vinyl‐modified 2′‐deoxyribonucleoside triphosphates, and the influence of the vinyl group in the major groove of DNA on the cleavage by diverse type II restriction endonucleases (REs) was studied. The presence of 5‐vinyluracil was tolerated by most of the REs, whereas only some REs were able to cleave sequences containing 7‐deaza‐7‐vinyladenine. The enzyme ScaI was found to cleave DNA containing 5‐vinylcytosine efficiently but not DNA containing the related 5‐ethynylcytosine. All other REs failed to cleave sequences containing any cytosine modifications.     

Millipedes That Smell Like Bugs: (E)-Alkenals in the Defensive Secretion of the Julid Diplopod Allajulus Dicentrus

The secretions from serial defensive glands of the Austrian diplopod Allajulus dicentrus (Julidae, Cylindroiulini) were extracted and analyzed by means of gas chromatography - mass spectrometry. In adults, 13 components from two chemical classes were detected: 1) The common juliform benzoquinones were represented by four compounds (2-hydroxy-3-methyl-1,4-benzoquinone, 2-methoxy-3-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, and 2,3-dimethoxy-5-methyl-1,4-benzoquinone). From this series, 2-methoxy-3-methyl-1,4-benzoquinone was most abundant, comprising about 40?% of the whole secretion. 2) All remaining compounds were identified as aliphatic (E)-alkenals [(E)-2-heptenal, (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal)] along with their corresponding alcohols. (E)-2-Octenal was most abundant, roughly accounting for another 35?% of the secretion. In juveniles, different stages in the ontogenetic development of the secretion were observed, with early instars (stadium III and IV) exclusively containing the benzoquinone fraction. Alkenols and alkenals were added in later instars (stadium V and VI), with secretions of stadium VI-juveniles being already similar to those of adults. Representatives of Spirostreptida, Spirobolida, and Julida traditionally have been considered to produce benzoquinonic secretions only ("quinone millipedes"), and information on secretion components from other chemical classes is still scarce. We here provide evidence for the participation of non-quinonic compounds in the defensive exudates of the Cylindroiulini. The occurrence of additional, non-quinonic compounds in certain species within a chemically homogenous, benzoquinone-producing taxon indicates the rapid adoption of novel exocrine compounds, possibly in order to meet the demands in a changed ecological environment.     

Single-breath-hold 3-D CINE imaging of the left ventricle using Cartesian sampling

Objectives

Our objectives were to evaluate a single-breath-hold approach for Cartesian 3-D CINE imaging of the left ventricle with a nearly isotropic resolution of \(1.9 \times 1.9 \times 2.5\,{\text {mm}^3}\) and a breath-hold duration of \(\sim \)19 s against a standard stack of 2-D CINE slices acquired in multiple breath-holds. Validation is performed with data sets from ten healthy volunteers.

Materials and methods

A Cartesian sampling pattern based on the spiral phyllotaxis and a compressed sensing reconstruction method are proposed to allow 3-D CINE imaging with high acceleration factors. The fully integrated reconstruction uses multiple graphics processing units to speed up the reconstruction. The 2-D CINE and 3-D CINE are compared based on ventricular function parameters, contrast-to-noise ratio and edge sharpness measurements.

Results

Visual comparisons of corresponding short-axis slices of 2-D and 3-D CINE show an excellent match, while 3-D CINE also allows reformatting to other orientations. Ventricular function parameters do not significantly differ from values based on 2-D CINE imaging. Reconstruction times are below 4 min.

Conclusion

We demonstrate single-breath-hold 3-D CINE imaging in volunteers and three example patient cases, which features fast reconstruction and allows reformatting to arbitrary orientations.

     

Classification criteria and probability risk maps: limitations and perspectives

Delineation of polluted zones with respect to regulatory standards, accounting at the same time for the uncertainty of the estimated concentrations, relies on classification criteria that can lead to significantly different pollution risk maps, which, in turn, can depend on the regulatory standard itself. This paper reviews four popular classification criteria related to the violation of a probability threshold or a physical threshold, using annual (1996-2000) nitrogen dioxide concentrations from 40 air monitoring stations in Milan. The relative advantages and practical limitations of each criterion are discussed, and it is shown that some of the criteria are more appropriate for the problem at hand and that the choice of the criterion can be supported by the statistical distribution of the data and/or the regulatory standard. Finally, the polluted area is estimated over the different years and concentration thresholds using the appropriate risk maps as an additional source of uncertainty.     

Detection of Proteinases in Saccharomyces cerevisiae by Flow Cytometry

The physiological state of a yeast population used for inoculation determines how rapidly the cells adapt to new environmental conditions, begin proliferating and utilising extract. The decision as to whether a yeast culture is suitable for re‐pitching should not be based only on viability determinations since this can be misleading. Increased proteolytic activity in a yeast population indicates the onset of senescence. A flow cytometric method has been developed for measuring a wide variety of proteinases in Saccharomyces cerevisiae employing a commercially available casein‐dye conjugate. The detection of intracellular proteinase activity gives an early indication of apoptotic events and allows improved assessment of the physiological state of a yeast population. This knowledge will assist the industry to optimize the selection of yeast and its subsequent fermentation performance. Yeast cell autolysis with all its negative consequences for beer quality and stability will thus be minimised.     

Phenolic compounds in tomatoes. Natural variations and effect of gamma-irradiation

A method for determination of p-hydroxybenzaldehyde, p-coumaric acid, ferulic acid, rutin and naringenin in tomatoes based on HPLC with coulometric electrode array detection was developed. After lyophilisation and extraction the compounds were separated isocratically (acetonitrile/buffer: 14:86, v:v, or acetonitrile/buffer: 27:73, v:v, flow rate: 0.8 ml/min) on reversed phase columns (LiChrospher 60 RP select B or Spherisorb ODS2) and detected at 16 respectively 10 working electrodes set at potentials between +50 and +750 mV against palladium reference electrodes. The natural content of these components showed a strong variation between different varieties, harvests and degrees of maturity. Gamma-irradiation reduced the concentration of the phenolic compounds markedly in all tomato samples investigated, however, this change was smaller than the naturally occurring differences. The irradiation products vanillin and eriodictyol, identified in standard solutions, could not be found in irradiated tomatoes.     

The inhibition by naphthoquinones and anthraquinones of 2-amino-3-methylimidazo[4,5-f?]quinoline metabolic activation to a mutagen: a structure-activity relationship study

 Nine naphthoquinones, 19 anthraquinones, and nine structurally related monoketonic compounds such as anthrone, xanthone, etc., inhibited mutagenicity induced by 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in Salmonella typhimurium TA 98 in the presence of rat liver S9 with distinct structure-activity relationships. A carbonyl function was a prerequisite for antimutagenicity while, in general, anthraquinones (IC₅₀ values: 2.3–>213 nmol/ml top agar) were more potent antimutagens than structurally related monoketonic compounds (IC₅₀ values: 25.3–94.9 nmol/ml top agar) and naphthoquinones (IC₅₀ values: 3.7–90.7 nmol/ml top agar). The parent compounds and methyl substituted derivatives were already the most potent while introduction of polar substituents such as COOH and SO₃H considerably reduced antimutagenicity. Introduction of OH functions had equivocal effects: with increasing numbers, antimutagenic potencies were concomitantly reduced; however, anthraflavic acid, chrysazin, quinizarin, and especially 5,8-dihydroxy-1,4-naphthoquinone were more potent than the parent compounds. The patterns of inhibition by quinones of 7-ethoxyresorufin-O-dealkylase activities in rat liver microsomes, linked to cytochrome P-450-dependent oxidation of IQ to N-hydroxy-IQ (N-OH-IQ), were in general identical with those obtained in the Salmonella/reversion assay except for chrysophanic acid, emodin, and some naphthoquinones which were very potent in this assay (IC₅₀: 0.20–45.0 μM). On the other hand, mutagenicity of N-OH-IQ in S. typhimurium TA 98NR was not inhibited by nonpolar quinones (except 1,4-naphthoquinone) but rather by polar compounds and especially by hydroxyquinones (IC₅₀ values: 5.3–106.7 nmol/ml top agar or not reached). Inhibition of mutagenic activities of IQ, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-6-methyldipyrido[1,2-a:3′,2′-d]imidazole, and 3-amino-1-methyl-5H-pyrido[4,3-b]indole by chrysazin, chrysophanic acid, physicon, and purpurin varied, but no clearcut structure-activity relationships of the mutagens were observed. Received: 29 May 1998     

Factors affecting consumers' preferences for and purchasing decisions regarding pasteurized and raw milk specialty cheeses

Eight hundred ninety consumers at a local food festival were surveyed about their specialty cheese purchasing behavior and asked to taste and rate, through nonforced choice preference, 1 of 4 cheese pairs (Cheddar and Gouda) made from pasteurized and raw milks. The purpose of the survey was to examine consumers’ responses to information on the safety of raw milk cheeses. The associated consumer test provided information about specialty cheese consumers’ preferences and purchasing behavior. Half of the consumers tested were provided with cheese pairs that were identified as being made from unpasteurized and pasteurized milk. The other half evaluated samples that were identified only with random 3-digit codes. Overall, more consumers preferred the raw milk cheeses than the pasteurized milk cheeses. A larger portion of consumers indicated preferences for the raw milk cheese when the cheeses were labeled and thus they knew which samples were made from raw milk. Most of the consumers tested considered the raw milk cheeses to be less safe or did not know if raw milk cheeses were less safe. After being informed that the raw milk cheeses were produced by a process approved by the FDA (i.e., 60-d ripening), most consumers with concerns stated that they believed raw milk cheeses to be safe. When marketing cheese made from raw milk, producers should inform consumers that raw milk cheese is produced by an FDA-approved process.