http://www.uniroma2.it/didattica/tbs2/deposito/Manufacture,_characterisation_and_application_of_cellular_metals_and_metal_foams.pdf

Manufacture, characterisation and application of cellular metals and metal foams

Cells can endure storage at low temperatures such as--196 degrees C for centuries. The challenge is to determine how they can survive both the cooling to such temperatures and the subsequent return to physiological conditions. A major factor is whether they freeze intracellularly. They do so if cooling is too rapid, because with rapid cooling insufficient cell water is removed osmotically to eliminate supercooling. Equations have been developed that describe the kinetics of this water loss and permit one to predict the likelihood of intracellular freezing as a function of cooling rate. Such predictions agree well with observations. Although the avoidance of intracellular freezing is usually necessary for survival, it is not sufficient. Slow freezing itself can be injurious. As ice forms outside the cell, the residual unfrozen medium forms channels of decreasing size and increasing solute concentration. The cells lie in the channels and shrink in osmotic response to the rising solute concentration. Prior theories have ascribed slow freezing injury to the concentration of solutes or the cell shrinkage. Recent experiments, however, indicate that the damage is due more to the decrease in the size of the unfrozen channels. This new view of the mechanism of slow freezing injury ought to facilitate the development of procedures for the preservation of complex assemblages of cells of biological, medical, and agricultural significance.

Freezing of living cells: mechanisms and implications

Starting from known properties of non-specific salt effects on the surface tension at an air–water interface, we propose the first general, detailed qualitative molecular mechanism for the origins of ion-specific (Hofmeister) effects on the surface potential difference at an air–water interface; this mechanism suggests a simple model for the behaviour of water at all interfaces (including water–solute interfaces), regardless of whether the non-aqueous component is neutral or charged, polar or non-polar Specifically, water near an isolated interface is conceptually divided into three layers, each layer being 1 water-molecule thick We propose that the solute determines the behaviour of the adjacent first interfacial water layer ( I 1 ); that the bulk solution determines the behaviour of the third interfacial water layer ( I 3 ), and that both I 1 and I 3 compete for hydrogen-bonding interactions with the intervening water layer ( I 2 ), which can be thought of as a transition layer The model requires that a polar kosmotrope (polar water-structure maker) interact with I 1 more strongly than would bulk water in its place; that a chaotrope (water-structure breaker) interact with I 1 somewhat less strongly than would bulk water in its place; and that a non-polar kosmotrope (non-polar water-structure maker) interact with I 1 much less strongly than would bulk water in its place We introduce two simple new postulates to describe the behaviour of I 1 water molecules in aqueous solution The first, the ‘relative competition’ postulate, states that an I 1 water molecule, in maximizing its free energy (—δG), will favour those of its highly directional polar (hydrogen-bonding) interactions with its immediate neighbours for which the maximum pairwise enthalpy of interaction (—δ H ) is greatest; that is, it will favour the strongest interactions We describe such behaviour as ‘compliant’, since an I 1 water molecule will continually adjust its position to maximize these strong interactions Its behaviour towards its remaining immediate neighbours, with whom it interacts relatively weakly (but still favourably), we describe as ‘recalcitrant’, since it will be unable to adjust its position to maximize simultaneously these interactions The second, the ‘charge transfer’ postulate, states that the strong polar kosmotrope–water interaction has at least a small amount of covalent character, resulting in significant transfer of charge from polar kosmotropes to water–especially of negative charge from Lewis bases (both neutral and anionic); and that the water-structuring effect of polar kosmotropes is caused not only by the tight binding (partial immobilization) of the immediately adjacent ( I 1 ) water molecules, but also by an attempt to distribute among several water molecules the charge transferred from the solute When extensive, cumulative charge transfer to solvent occurs, as with macromolecular polyphosphates, the solvation layer (the layer of solvent whose behaviour is determined by the solute) can become up to 5- or 6-water-molecules thick We then use the ‘relative competition’ postulate, which lends itself to simple diagramming, in conjunction with the ‘charge transfer’ postulate to provide a new, startlingly simple and direct qualitative explanation for the heat of dilution of neutral polar solutes and the temperature dependence of relative viscosity of neutral polar solutes in aqueous solution This explanation also requires the new and intriguing general conclusion that as the temperature of aqueous solutions is lowered towards o °C, solutes tend to acquire a non-uniform distribution in the solution, becoming increasingly likely to cluster 2 water molecules away from other solutes and surfaces (the driving force for this process being the conversion of transition layer water to bulk water) The implications of these conclusions for understanding the mechanism of action of general (gaseous) anaesthetics and other important interfacial phenomena are then addressed

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033583500005369

The Hofmeister effect and the behaviour of water at interfaces.

The anomalous properties of cold and supercooled water, such as the fact that at sufficiently low temperatures it becomes more compressible and less dense when cooled, and more fluid when compressed, have attracted the attention of physical scientists for a long time. The discovery in the 1970s that several thermodynamic and transport properties of supercooled water exhibit a pronounced temperature dependence and appear to diverge slightly below the homogeneous nucleation temperature inspired a large number of experimental and theoretical studies. Likewise, an important body of work on glassy water has been stimulated by experiments, starting in the mid-1980s and continuing to this date, which suggest that vitreous water can exist in at least two apparently distinct forms. A coherent theory of the thermodynamic and transport properties of supercooled and glassy water does not yet exist. Nevertheless, significant progress towards this goal has been made during the past 20 years. This article summarizes the known experimental facts and reviews critically theoretical and computational work aimed at interpreting the observations and providing a unified viewpoint on cold, non-crystalline, metastable states of water.

https://iopscience.iop.org/article/10.1088/0953-8984/15/45/R01/pdf

Supercooled and glassy water

Chapter 1: AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations.

Using an experimental system that mimics stone fragmentation in the renal pelvis, we have investigated the role of stress waves and cavitation in stone comminution in shock-wave lithotripsy (SWL). Spherical plaster-of-Paris stone phantoms (D = 10 mm) were exposed to 25, 50, 100, 200, 300 and 500 shocks at the beam focus of a Dornier HM-3 lithotripter operated at 20 kV and a pulse repetition rate of 1 Hz. The stone phantoms were immersed either in degassed water or in castor oil to delineate the contribution of stress waves and cavitation to stone comminution. It was found that, while in degassed water there is a progressive disintegration of the stone phantoms into small pieces, the fragments produced in castor oil are fairly sizable. From 25 to 500 shocks, clinically passable fragments (< 2 mm) produced in degassed water increases from 3% to 66%, whereas, in castor oil, the corresponding values are from 2% to 11%. Similar observations were confirmed using kidney stones with a primary composition of calcium oxalate monohydrate. After 200 shocks, 89% of the fragments of the kidney stones treated in degassed water became passable, but only 22% of the fragments of the kidney stones treated in castor oil were less than 2 mm in size. This apparent size limitation of the stone fragments produced primarily by stress waves (in castor oil) is likely caused by the destructive superposition of the stress waves reverberating inside the fragments, when their sizes are less than half of the compressive wavelength in the stone material. On the other hand, if a stone is only exposed to cavitation bubbles induced in SWL, the resultant fragmentation is much less effective than that produced by the combination of stress waves and cavitation. It is concluded that, although stress wave-induced fracture is important for the initial disintegration of kidney stones, cavitation is necessary to produce fine passable fragments, which are most critical for the success of clinical SWL. Stress waves and cavitation work synergistically, rather than independently, to produce effective and successful disintegration of renal calculi in SWL

The role of stress waves and cavitation in stone comminution in shock wave lithotripsy.

Transient cavitation and shockwave generation produced by pulsed-dye and holmium:YAG laser lithotripters were studied using high-speed photography and acoustic emission measurements. In addition, stone phantoms were used to compare the fragmentation efficiency of various laser and electrohydraulic lithotripters. The pulsed-dye laser, with a wavelength (504 nm) strongly absorbed by most stone materials but not by water, and a short pulse duration of ∼1 μsec, induces plasma formation on the surface of the target calculi. Subsequently, the rapid expansion of the plasma forms a cavitation bubble, which expands spherically to a maximum size and then collapses violently, leading to strong shockwave generation and microjet impingement, which comprises the primary mechanism for stone fragmentation with short-pulse lasers. In contrast, the holmium laser, with a wavelength (2100 nm) most strongly absorbed by water as well as by all stone materials and a long pulse duration of 250 to 350 μsec, produces an e...

Transient Cavitation and Acoustic Emission Produced by Different Laser Lithotripters

The invention relates to a method for the comminution of concretions in vivo by controlled, concentrated cavitation energy. This method utilizes two shock wave pulses (7, 8) with a specified time delay (3) and pressure relationship, with the first shock wave pulse (7) being used to induce a transient cavitation bubble cluster (9) near the target concretion (4), and the second shock wave pulse (8) to control and force the collapse of the cavitation bubble cluster towards the target concretion (4) with concentrated energy disposition, while avoiding injury to surrounding tissue caused by random collapse of the cavitation bubbles (9). This invention makes it possible to significantly enhance the fragmentation efficiency of the concretion using shock waves while reducing potential deleterious injury to surrounding tissue.

Method for the comminution of concretions

Phase diagram relationships in cryobiology.

The inertial cavitation and associated acoustic emission generated during electrohydraulic shock wave lithotripsy were studied using high-speed photography and acoustic pressure measurements. The dynamics of cavitation bubble clusters, induced in vitro by an experimental laboratory lithotripter, were recorded using a high-speed rotating drum camera at 20 000 frames/s. The acoustic emission, generated by the rapid initial expansion and subsequent violent collapse of the cavitation bubbles, was measured simultaneously using a 1-MHz focused hydrophone, The expansion duration of the cavitation bubble cluster was found to correlate closely with the time delay between the first two groups of pressure spikes in the acoustic emission signal. This correlation provides an essential physical basis to assess the inertial cavitation produced by a clinical Dornier HM-3 shock wave lithotripter, both in water and in renal parenchyma of a swine model. In the clinical output voltage range (16–24 kV), the expansion duration...

Franklin H. Cocks

Papers

The role of stress waves and cavitation in stone comminution in shock wave lithotripsy.

Transient Cavitation and Acoustic Emission Produced by Different Laser Lithotripters

Method for the comminution of concretions

Phase diagram relationships in cryobiology.

Inertial cavitation and associated acoustic emission produced during electrohydraulic shock wave lithotripsy