Comments on the High Pressure Preservation of Human Milk

The current state of studies on the high pressure preservation of the human milk is briefly presented. It is indicated that reaching (i) the antimicrobial safety, (ii) antiviral safety, and (iii) high nutritional, metabolic and immunological quality, may be difficult for a “classical” single pressure pulse High Pressure Preservation (HPP) treatment. It is shown that the sudden decompression leads to additional physical processes, which can be important for supporting the HPP technology. Additional advantages were reached due to the two-pulse compression, with subsequent values: P = 200 MPa and 400 MPa. Tests included the microbiological insight for the two-weeks storage. It is also shown that the decay of the number of microorganisms under the high pressure follows the relation n(t) = n0exp(At)exp(Bt2). Finally, issues regarding containers for the high pressure preservation of human milk are discussed

Pressure behaviour of dielectric permittivity on approaching the near-critical consolute point

Results are presented of studies on dielectric permittivity (ε) for the isothermal pressure (P) path of approaching the near-critical consolute point in 1-nitropropane–hexadecane solution. The pretransitional anomaly is well portrayed by the relation isomorphic to that applied in temperature (T) studies under atmospheric pressure. However, the $\varepsilon(P)$ anomaly is much larger, with almost negligible influence of correction-to-scaling terms and the low-frequency Maxwell-Wagner dispersion (even for $f = 1\;{\rm kHz}$), than it was observed in temperature studies at atmospheric pressure. This makes possible a reliable estimation of a critical exponent $\phi = 1 - \alpha \approx 0.88$ which accounts for the critical anomaly. Discrepancies between the $\varepsilon(P)$ and the $\varepsilon(T)$ behaviour may be associated with different positions of isothermal pressure and isobaric temperature paths of approaching the critical consolute point

Glassy and fluidlike behavior of the isotropic phase of n-cyanobiphenyls in broad-band dielectric relaxation studies

It is shown that the temperature behavior of peaks $\left( f_p,\varepsilon _p^{\prime\prime}\right)$ of dielectric loss curves in the isotropic phase of $n$-cyanobiphenyls $\left( n=8,9,10\right)$ with isotropic-nematic and isotropic-smectic A transitions exhibits features characterisic for both supercooled, glass-forming liquids and critical, binary mixtures. The behavior of $f_p\left( T\right)$ can be portrayed by the Vogel-Fulcher-Tamman relation and the “critical-like”, mode-coupling theory (MCT) equation. The latter is supported by the novel analysis of electric conductivity $\sigma \left( T\right)$. The obtained $f_p\left( T\right)$ and $\sigma \left( T\right)$ dependencies can be related by using the fractional Debye-Einstein-Stokes law. For all tested mesogens the static dielectric permittivities $\varepsilon ^{\prime}\left( T\right)$ and $\varepsilon _p^{\prime\prime}\left( T\right)$ are described by dependencies resembling those applied in the homogeneous phase of critical mixtures but with specific-heat critical exponent $\alpha \approx 0.5$. This behavior agrees with the novel fluidlike description for the isotropic-nematic transition (P.K. Mukherjee, Phys. Rev. E 51, 5745 (1995); A. Drozd-Rzoska, Phys. Rev. E 59, 5556 (1999)). The obtained glassy features of dielectric relaxation support the recent simulation analysis carried out by M. Letz et al.  (Phys. Rev. E 62, 5173 (2000))