Using GFP-tagged Saccharomyces cerevisiae strains, the nucleus, endoplasmic reticulum (ER), and Golgi apparatus were visualized to examine the relationship between organelle damage and cell inactivation induced by high hydrostatic pressure (HHP). Cell inactivation was strongly dependent on growth phase, whereas organelle damage occurred largely independently of growth phase. Among the organelles examined, only Golgi apparatus damage showed a clear association with cell inactivation in the stationary phase. These findings suggest that pressure-induced disruption of Golgi-associated structures and/or protein localization, rather than nuclear or ER damage, may be closely associated with HHP-induced yeast inactivation, possibly through impairment of intracellular secretion and protein trafficking. This study provides new insights into organelle-specific responses to HHP treatment and contributes to a better understanding of microbial inactivation mechanisms under high-pressure conditions.
Self-consistent thermodynamic description of a mixture (a compound, an alloy, etc.) including both its equation of state (EOS) and solidus and liquidus boundaries is a challenging problem. We review several standard approaches with the associated mixing rules and discuss their shortcomings. We propose a new thermodynamics-based analytic model for the EOS of a N-component mixture, $N\geq 2$N >= 2. The model uses N-1 free parameters the values of which can be easily determined from the available experimental data. The calculation of the liquidus surface of a N-component mixture, which the model also suggests, requires the knowledge of the melting curves of each of the constituents of the mixture, but no other information such as their EOSs is really needed. We apply the new model to a ternary mixture in general, and to the ThO$_2$2-UO$_2$2-PuO$_2$2 mixed-oxide (MOX) system as an example in particular.
The laser-heated diamond anvil cell is widely used for experiments under extreme conditions, though pressure and temperature measurements often remain sources of error and inconsistency across studies. This work emphasizes the importance of accurately measuring the temperature distribution across the sample using an enhanced laser-heating setup and a four-color pyrometry system. Pressure calibration was improved by developing a dedicated protocol based on X-ray diffraction measurements of recrystallizing KCl in contact with the sample, bringing pressure and temperature readings closer to the actual sample conditions. When recrystallized KCl is not visible in diffraction patterns, we propose a thermal-pressure correction based on finite element simulations and validated against KCl metrology, which provides greater accuracy than previous methods. As a case study, the methodology was applied to determine the melting curves of Fe-FeO iron-w & uuml;stite and FeO w & uuml;stite.
High-pressure Raman scattering measurements on sodium borohydride dihydrate NaBH4 & centerdot;2H2O were performed up to 8.5 GPa to investigate the structural changes during dehydration and the transformation previously observed by X-ray diffraction. Density functional theory calculations were used to identify the Raman modes of NaBH4 & centerdot;2H2O. Below 4.6 GPa, the wavenumbers of the B-H stretching modes blue-shifted with increasing pressure, whereas the O-H bending modes red-shifted slightly and the O-H stretching modes remained nearly constant. Pressure-induced dehydration of NaBH4 & centerdot;2H2O occurred at 4.6 GPa, producing alpha-NaBH4 and ice VII. Subsequently, the decomposed NaBH4 underwent a phase transition to gamma-NaBH4 at 6.6 GPa. During decompression, a reversible transition from gamma-NaBH4 to alpha-NaBH4 occurred at 5.5 GPa, followed by the regeneration of NaBH4 & centerdot;2H2O at 3.2 GPa. These results are consistent with those of the X-ray diffraction measurements observed previously.
