An Explanation of the Removal of Metastability in Some Hydroacid Salts by Water Adsorption

Abstract The metastability of some phases of CsHSO4 and RbH2PO4 is due to the volume decrease at an endothermic phase transition which "locks in" the metastability in question. Water adsorption, which removes these metastabilities, probably exerts a "wedge-like" force which expands the lattice spacing in the surface layer, thus facilitating the start of the phase transition. The induction time and the zeroth order kinetics of the transition in RbH2PO4 are exponential functions of the water activity applied.

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Temperature Effect on the Two-Dimensional Phase Transition Kinetics of Adenine Adsorbed at the Hg Electrode/Aqueous Solution Interface

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20031407 ◽

2003 ◽

Vol 68 (8) ◽

pp. 1407-1419 ◽

Cited By ~ 3

Author(s):

Claudio Fontanesi ◽

Roberto Andreoli ◽

Luca Benedetti ◽

Roberto Giovanardi ◽

Paolo Ferrarini

Keyword(s):

Phase Transition ◽

Aqueous Solution ◽

Phase Change ◽

Temperature Effect ◽

Transition Rate ◽

Effect Of Temperature ◽

Two Dimensional ◽

Solution Interface ◽

Phase Transition Kinetics ◽

Kinetics Of

The kinetics of the liquid-like → solid-like 2D phase transition of adenine adsorbed at the Hg/aqueous solution interface is studied. Attention is focused on the effect of temperature on the rate of phase change; an increase in temperature is found to cause a decrease of transition rate.

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Chemical and Physical Properties of Some Hazelnut Varieties Grown in Portugal

Agronomy ◽

10.3390/agronomy11081476 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1476

Author(s):

Ana Cristina Ferrão ◽

Raquel P. F. Guiné ◽

Elsa Ramalhosa ◽

Arminda Lopes ◽

Cláudia Rodrigues ◽

...

Keyword(s):

Discriminant Analysis ◽

Physical Properties ◽

Water Activity ◽

Induction Time ◽

Oxidation Stability ◽

Chemical Properties ◽

Physical And Chemical Properties ◽

Nutritional Characteristics ◽

Physical And Chemical ◽

And Chemical Properties

Hazelnuts are one of the most appreciated nuts worldwide due to their unique organoleptic and nutritional characteristics. The present work intended to analyse several physical and chemical properties of different hazelnut varieties grown in Portugal, namely Tonda de Giffoni, Grada de Viseu, Segorbe, Longa de Espanha, Butler, Gunslebert, and Negreta. In general, the results revealed statistically significant differences between the varieties under study. The Gunslebert had more elongated hazelnuts and with heavier shelled fruits, while the kernels of the Grada de Viseu revealed to be heavier. Grada de Viseu was harder in the shell, Gunslebert had a harder core, and Segorbe was more resistant to fracture. Fat was the more representative component for all varieties and in some cases the values of moisture and water activity were over the recommended amount (≥0.62). Tonda de Giffoni was the variety with the highest induction time, indicating the highest oxidation stability. Moreover, discriminant analysis revealed that the variables more important to distinguish the varieties were protein (λ = 0.007) and water activity (λ = 0.010). The results of this study help to better understand the differences between some hazelnut varieties that are cultivated in Portugal, which gives important hints for all players in the hazelnut sector.

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