Possible involvement of psychrotolerant Enterobacteriaceae in blown pack spoilage of vacuum-packaged raw meats

Recent investigations of blown pack spoilage in New Zealand chilled vacuum-packaged meats have found moderate to high numbers of Enterobacteriaceae in the spoilage flora, but no clostridia, such as C. estertheticum and C. gasigenes, that are usually associated with blown pack spoilage. This study showed that pyschrotolerant Enterobacteriaceae produced gas in a lamb homogenate model under anaerobic conditions and that these organisms could cause blown pack spoilage of vacuum-packaged chilled meats. Significant gas production was observed with the majority of the psychrotolerant Enterobacteriaceae strains tested including presumptive species of Enterobacter, Serratia, Hafnia and Rahnella. However, no gas was produced in lamb homogenates inoculated with presumptive species of Ewingella americana or Yersinia enterocolitica. Gas production was also confirmed in vacuum-packaged lamb shoulders stored at 4 degrees C for 21 days after being inoculated with individual representative Enterobacteriaceae isolates. Biochemical characterisation proved to be more useful than genotype-based typing of 16S rRNA genes for discriminating different psychrotolerant Enterobacteriaceae from naturally contaminated meat microflora.     

Increased apoptosis and DNA double-strand breaks in the embryonic mouse brain in response to very low-dose X-rays but not 50 Hz magnetic fields

The use of X-rays for medical diagnosis is enhancing exposure to low radiation doses. Exposure to extremely low-frequency electromagnetic or magnetic fields is also increasing. Epidemiological studies show consistent associations of childhood leukaemia with exposure to magnetic fields but any causal relationship is unclear. A limitation in assessing the consequence of such exposure is the availability of sensitive assays. The embryonic neuronal stem and progenitor cell compartments are radiosensitive tissues. Using sensitive assays, we report a statistically significant increase in DNA double-strand break (DSB) formation and apoptosis in the embryonic neuronal stem cell compartment following in utero exposure to 10–200 mGy X-rays. Both endpoints show a linear response. We also show that DSB repair is delayed following exposure to doses below 50 mGy compared with 100 mGy. Thus, we demonstrate in vivo consequences of low-dose radiation. In contrast to these impacts, we did not observe any significant induction of DSBs or apoptosis following exposure to 50 Hz magnetic fields (100 or 300 µT). We conclude that any DSB induction by treatment with magnetic fields is lower than following exposure to 10 mGy X-rays. For comparison, certain procedures involving computed tomography scanning are equivalent to 1–5 mGy X-rays.     

Recognition of uncertainty in emotional inferences: Reasoning about emotionally equivocal situations.

Three experiments investigated children's and adults' understanding of the uncertainty inherent in emotionally equivocal situations (i.e., situations that commonly elicit different feelings in different people). Students in 1st grade, 3rd grade, 6th grade, and college heard scenarios in which a peer experienced an emotionally equivocal or unequivocal event. Children, and to some degree adults, were overconfident about how individuals felt in equivocal situations. The tendency to acknowledge only 1 emotional possibility appeared to reflect difficulty in recognizing the plausibility of alternatives. Neither prompting children to give greater consideration to alternatives nor reminding them of the existence of individual differences produced greater discrimination between equivocal and unequivocal situations. In contrast, children recognized uncertainty when there was variability in the situation or within the individual. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electromechanical Properties of Some Pb (Mg1/3Nb2/3–PbTiO3–(Ba,Sr)TiO3 Ceramics: I

Compositional variation within the Pb(Mg_1/3Nb_2/3) O₃–PbTiO₃–(Ba, Sr)TiO₃ (hereafter PMN–PT–BT,ST) ternary (6.4% PT% 14.1%, 1.25% BT,ST% 2.5%) results in major changes in induced strain and hysteresis. For the 1.25% BT family, the increase in strain correlates with an increase in T _max, while the dielectric loss is uncorrelated with hysteresis and strain. In addition, weak field aging (which is not reset by application of field) shows little effect on strain and hysteresis for drive fields of > 0.2 MV/m. The vary narrow polarization-fields loops (virgin curvesnearly indistinguishable from subsequent cycles) show that weak-field permittivity is a good approximation to the high-field permittivity. is a good approximation to the high-field Permittivity. Although these data clarify the frequency ( T _max is linearly dependent on the logarithm of the frequency) effect on weak-field dielectric behavior, they do not directly address the question of meaningful extrapolation of high-field strain with frequency. In particular, the question remains as to whether the high-field permittivity and strain are frequency dependent. In future papers we will address this question by a combination of measurement techniques as functions of frequency.     

Children's use of situational information to infer emotion: Understanding emotionally equivocal situations.

Children's recognition of individual differences in people's emotional reactions to situations was investigated. Children in kindergarten, first, second, and third grades heard scenarios in which a child experienced an emotionally equivocal or unequivocal event. Children were asked several questions to assess their ability to discriminate between the equivocal and unequivocal situations. Results indicated that school-age children are aware that almost everyone feels the same about unequivocal situations but that there are individual differences in reactions to equivocal situations. Yet these children often fail to consider that a particular individual might feel 1 of 2 different emotions in an equivocal situation. The ability to consider more than one emotional possibility for an individual increases with age. Two follow-up studies helped to clarify the meaning of these findings. Implications for children's social sensitivity are discussed. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Number of inhomogeneities at which the effective moduli of a heterogeneous material stabilize

When the effective elastic moduli of heterogeneous materials containing inhomogeneities are numerically calculated, one of the issues is the number of inhomogeneities at which the effective moduli stabilize. This number may depend on the shape and distribution of the inhomogeneities. In this study, circular holes of the same size are considered. Two distributions of holes, equilateral triangular and random ones are analyzed. It is found that the effective moduli associated with the two distributions stabilize for the samples with seven and nineteen holes, respectively.     

Effect of a Minimal Spacing between Inhomogeneities on the Effective Moduli of Isotropic Plates with Circular Inhomogeneities

An interaction factor is used to characterize the effect of the interactions among inhomogeneities on the effective moduli. Many circular samples of plates are generated using a random number generator. When randomly generating a sample, a minimal spacing between inhomogeneities is set. Then, simulations using FEM are carried out to check the effect of the minimal spacing on the interaction factor. FEM results show that the interaction factor decreases as the minimal spacing increases.     

A general synthesis for PEDOT-coated nonconductive materials and PEDOT hollow particles by aqueous chemical polymerization

A method for coating functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) on nonconductive substrates in aqueous solution allows the deposition of PEDOT thin layers on various substrates, including silica and polystyrene (PS) nanoparticles, siliceous mesocellular foam, and chitosan-alginate fibers. The surface property is tuned by controlling the monomer composition in the aqueous solutions. Using appropriate organic solvents to remove the PS cores of PEDOT-coated PS nanoparticles, hollow PEDOT particles with single holes and PEDOT capsules can be formed.     

Mechanical Properties of Ternary Blends of ABS + HIPS + PETG

The effect of a commercial styrene/butadiene/styrene-based compatibilizer (Styroflex) on the tensile and impact properties of ternary blends of poly(acrylonitrile-co-butadiene-co-styrene) (ABS), high impact poly(styrene) (HIPS) and poly(ethylene terephthalate-co-cyclohexanedimethanol terephthalate) (PETG) was investigated. The tensile yield strengths and the moduli of the blends were of similar magnitude as the parent polymers. However, notched Charpy impact properties showed significant deviations with high synergy in ABS/PETG blends and strong antagonism in HIPS/PETG blends. Addition of Styroflex improved the impact properties of all blends containing HIPS and ABS. Dynamic mechanical analysis studies confirm the phase separated nature of ABS/PETG binary blends.