Gerald Pollack

University of Washington Seattle | UW · Department of Bioengineering

The heart is widely acknowledged as the unique driver of blood circulation. Recently, we discovered a flow-driving mechanism that can operate without imposed pressure, using infrared (IR) energy to propel flow. We considered the possibility that, by exploiting this mechanism, blood vessels, themselves, could propel flow. We verified the existence o...

Previously, we have shown that water adjacent to many hydrophilic substances excludes colloidal and molecular solutes. It was labelled “exclusion zone” (EZ) or “fourth phase” water. A salient feature is its characteristic light absorbance at or near 270 nm. In this study, EZ water formed against three chemically distinct surfaces, Nafion, ghee, and...

Hydrophilic materials immersed in aqueous solutions show near-surface zones that exclude suspended colloids and dissolved molecules. These exclusion zones (EZs) can extend for tens to hundreds of micrometers from hydrophilic surfaces and show physicochemical properties that differ from bulk water. Here we report that exposure of standard aqueous mi...

We investigated the effects of unipolar magnetic fields (N or S polarity) on the physical properties of deionized water. Long-term experiments (15 and 25 days) revealed significant pole-dependent changes in water absorption in the UV range (186 –230 nm), and in water evaporation. The order of absorption magnitudes was C-N-S. That is, control (C) wa...

Abstract We investigated the effects of unipolar magnetic fields (N or S polarity) on the physical properties of deionized water. Long-term experiments revealed significant pole-dependent changes in water absorption in the UV range (186 – 240 nm), and in water evaporation. The order of absorption magnitudes was C-N-S. That is, control (C) water abs...

Low frequency electric fields were exposed to various water samples using platinum electrodes mounted near the water surface. Responses were monitored using a spectro-radiometer and a contact-angle goniometer. Treatment of DI (deionized), EZ (Exclusion Zone), and bulk water with certain electromagnetic frequencies resulted in a drop of radiance per...

We investigated the effects of unipolar magnetic fields (N or S polarity) on the physical properties of deionized water. Long-term experiments revealed significant pole-dependent changes in water absorption in the UV range (180 – 350 nm). In the case of water in open vessels, the order of absorption values was C-N-S. That is, control (C) water abso...

Hydrophilic materials such as Nafion can nucleate the buildup of interfacial water, which shows features different from bulk water. We investigated the effect of infrared (IR) light on a negatively charged, interfacial exclusion zone (EZ) and a positively charged proton zone (PZ) formed in the vicinity of Nafion. After irradiation for 5 min by mid-...

The heart is widely acknowledged as the unique driver of blood circulation. Recently, we discovered a flow-driving mechanism that can operate without imposed pressure, using infrared (IR) energy to propel flow. We considered the possibility that, by exploiting this mechanism, blood vessels, themselves, could propel flow. We verified the existence o...

Hydration plays a particularly important role in health maintenance and general well-being. A wide assortment of drinking waters are currently available on the market. However, their ability to hydrate may vary. For studying hydration, a useful organism may be the cysts of brine shrimp. Those cysts may remain dehydrated and functionless for years,...

Propolis is a natural product originating from life activity of honeybees. It exhibits wide range of biological properties applicable in medicine, the food industry, and cosmetics. Chemically, propolis is a complex and variable mixture with more than 300 identified biologically active components. Propolis's many health-promoting effects are attribu...

The ionic compositions of the intra- and extracellular environments are distinct from one another, with K⁺ being the main cation in the cytosol and Na⁺ being the most abundant cation outside of the cell. Specific ions can permeate into and out of the cell at different rates, bringing about uneven distribution of charges and development of negative...

A fourth phase of water, labeled exclusion-zone or "EZ," extends from hydrophilic surfaces. Salient features include exclusion of colloidal and molecular solutes, and characteristic light absorbance at 270 nm. In cell systems, EZ water interfaces with membranes, macromolecules, and organelles, and its buildup appears to be vital for function. For y...

Fluid commonly flows in response to an external pressure gradient. However, when a tunnel-containing hydrogel is immersed in water, spontaneous flow occurs through the tunnel without any pressure gradient. We confirmed this flow in a wide range of plant- and animal-derived hydrogels. The flow appears to be driven by axial concentration gradients or...

One of the characteristics of aqueous interfaces is their negative charge, whose origin is still a subject of a scientific debate. In this work we provide spectroscopic evidence that bicarbonate anions, from dissolution of atmospheric CO2, can be a source of negative charge at the air-water and/or solid-water interface. Also, interfacial charge sep...

While water evaporation and condensation are of fundamental importance to our environment, many features remain under investigation. In this study, we explored the water-condensation circle (WCC) formed on the inner surface of Petri dish lids covering containers of water. We found that they progressively diminished in diameter. Surprisingly, the di...

Silk sericin is a globular protein whose resistance against fouling is important for applications in biomaterials and water-purification membranes. Here it is shown how sericin generates a water-exclusion zone that may facilitate antifouling behavior. Negatively charged microspheres were used to mimic the surface charge and hydrophobic domains in b...

When droplets of purified water (1–5 μl) were cooled from the bottom, they slowly and continuously supercooled before releasing latent heat as a transient burst of infra-red (IR) radiation. In order to determine the role of this IR emission, a thin rectangular water layer was cooled unilaterally while imaged from above by an infrared (FLIR) camera....

It is now well-confirmed that hydrophilic surfaces including those within the cell generate structural changes in water. This interfacial water is ordered and acquires features different from the bulk. Amongst those features is the exclusion of colloidal and molecular solutes from extensive regions next to the hydrophilic surface, thereby earning i...

Earlier studies have reported the formation of an exclusion zone devoid of microspheres at the interface of water with a hydrophilic surface such as Nafion® or the hydrophilic ceramic powder. We now report the formation of a 'three-dimensional cell-like structured exclusion zone' in water prepared by two different methods. In the first, the hydroph...

Water is known to have three phases, solid, liquid, and vapor. However, we discovered a fourth phase, lying in between solid and liquid. While the evidence for this phase is relatively new, the concept of a fourth, ordered, phase of water dates back at least a century. This recently identified phase carries with it considerable explanatory power fo...

Hydrogels contain ample amounts of water, with the water-to-solid ratio sometimes reaching tens of thousands of times. How can so much water remain securely lodged within the gel? New findings imply a simple mechanism. Next to hydrophilic surfaces, water transitions into an extensive gel-like phase in which molecules become ordered. This “fourth ph...

The surface of ice plays a significant role in melting. To better understand the role of the surface, we studied the melting of ice using infrared imaging and pH-sensitive dyes. Ice was allowed to melt in baths of water of varying depth. When the ice melted in a high level of room-temperature water, equal to the height of the ice, the conventional...

A hydrophilic powder, QELBY, from the feldspar family of clay minerals was investigated for its ability to form structured or exclusion-zone (EZ) water. We demonstrated microsphere-free zones around different fractions of the QELBY powder or its hydrated pellet. Averaging approximately 100 μ m, these zones grew to a size similar to that formed in t...

Brownian particles suspended in water or other polar liquids are pushed out of the region next to hydrophilic polymers, leaving a microsphere-free region known as the “exclusion zone” (EZ). This study aimed to test the hypothesis that the dilution of ethanol in water may influence EZ formation. EZs were created in aqueous media using Nafion tubes a...

Background: Water undergoes structural change as it interfaces with hydrophilic surfaces, including the many hydrophilic surfaces within the cell. This interfacial water has become known as "Exclusion Zone (EZ) water" or "fourth-phase water" [1]. Methods: We tested the hypothesis that anesthetics diminish the amount of EZ water, and that this ch...

Colloidal particles in aqueous suspension generally sediment uniformly. By contrast, we found that suspensions of latex microspheres in polystyrene Petri dishes deviated sharply from the expected pattern when various objects were positioned immediately outside those dishes. When small coin-like metal discs were positioned immediately beneath the Pe...

Hyperbaric oxygen (HBO2) conditions are applied clinically to treat diverse conditions. There is a lack of a unifying consensus as to how HBO2 acts effectively against a broad range of medical conditions, and numerous differing biological explanations have been offered. The possibility of a mechanism dependent on the extensive ordering of interfaci...

The effect of atmospheric positivity on the electrical properties of interfacial water was explored. Interfacial, or exclusion zone (EZ) water was created in the standard way, next to a sheet of Nafion placed horizontally at the bottom of a water-filled chamber. Positive atmospheric ions were created from a high voltage source placed above the cham...

The dynamics of the development of solute exclusion zones produced by water in contact with various cellulosic surfaces are reported. The term “exclusion zone” (EZ) refers to the ordered water volume present immediately contiguous to hydrophilic surfaces. As such, three examples of cellulose-based films, i.e., cellophane, cellulose acetate with 0.9...

Protein-water interaction plays a crucial role in protein dynamics and hence function. To study the chemical environment of water and proteins with high spatial resolution, synchrotron radiation-Fourier transform infrared (SR-FTIR) spectromicroscopy was used to probe skeletal muscle myofibrils. Observing the OH stretch band showed that water inside...

The presence of large aqueous zones that exclude substances from the vicinity of various surfaces has become increasingly recognized. Two volumes have recently shown that such exclusion phenomena may address a number of previously unresolved issues in biology (Pollack et al., 2006; Pollack and Chin, 2008). And, with demonstrations of exclusion from...

We observed sustained axial flow through tubes immersed in water. The flow was spontaneous; i.e., no pressure gradient was applied. The tubes were made of hydrophilic materials: either the polymer Nafion, or a polyacrylic-acid gel in which a tunnel had been bored. Flow was monitored microscopically, with the aid of particles suspended in the water....

A self-driven flow was observed in Nafion and other hydrophilic tubes immersed in water. The intratubular flow was generated when water came in contact with the tube's hydrophilic surfaces. Flow characteristics were studied in tubes of varying size, exposed to light of different intensities and wavelengths. The results lead to the hypothesis that t...

Interfacial water lying next to hydrophilic surfaces has been shown to be spectroscopically, mechanically, and electrically distinct from bulk water. Interfacial water has also been shown to exclude negatively- and positively-charged microspheres, and has thus become known as the "exclusion zone". Measurements have demonstrated that exclusion zones...

Earlier, we reported solute-free “exclusion zones” in aqueous media next to various metal surfaces. Here we explore the effect of connecting zinc, which ordinarily shows a large exclusion zone, to platinum, which ordinarily does not. We found the connecting the two metals diminished the exclusion zone next to zinc, while it increased the exclusion...

Solute-free zones, termed "exclusion zones" are routinely seen next to hydrophilic surfaces in aqueous solution. Here we report similar zones next to various metals. The largest, approximately 200 µm in width, was found adjacent to zinc. Other reactive metals, including aluminum, tin, lead, and tungsten exhibited distinct but smaller exclusion zone...

In this perspective a definition of transformative research (TR) is proposed and discussed. We define TR as that which "transforms" or causes a major change in thought patterns concerning an area of scientific endeavor. This type of research is often elusive, requires different approaches and sometimes depends on a bit of luck. TR concerns intangib...

Experiments were carried out to explore the effect of light on Au, Pt and Cu surfaces immersed in water, in order to study the changes of work function arising from the interaction between the metallic surfaces and water. The results show an action of liquid water about three times larger than that of low-temperature ice. Theoretical calculations,...

The hypothesis is proposed that pre-biotic bacterial cell(s) and the first cells capable of growth/division did not require a cytoplasmic membrane. A gel-like microscopic structure less than a cubic micrometer may have had a dual role as both an ancient pre-cytoplasm and a boundary layer to the higher-entropy external environment. The gel pre-cytop...

Unexpectedly distinct patterns in evaporation were observed over heated water. Although the patterns had chaotic aspects, they often showed geometric patterns. These patterns bore strong resemblance to the infrared emission patterns observable with a mid-infrared camera focused on the water surface. This similarity puts constraints on the mechanism...

The conversion of ice to water is a process riddled with enigmas. We tested the possibility that ice does not transition directly to water, but first to an intermediate phase that has been recently identified. That intermediate is the interfacial \“exclusion zone” phase. The phase is characterized by strong absorption of light at 270 nm. We found i...

Many hydrophilic materials in aqueous solution show near-surface zones that exclude suspended colloids and dissolved molecules. These exclusion zones (EZs) can extend for tens to hundreds of micrometers from the hydrophilic surface, and show physicochemical properties that differ from bulk water. So far, only continuous surfaces of polymers, gels,...

Investigations carried out on single cardiac and bumblebee myofibrils have shown stepwise sarcomere-length change of ~2.7 nm.1 We have carried out parallel measurements on single myofibrils from rabbit psoas muscle. Activated specimens were released or stretched using a motor-imposed ramp. With a high-resolution algorithm, we found that step sizes...

The cell is rich with interfaces. But the role of these interfaces with water has received little attention among biologists, who generally consider water to be a mere background carrier of the more important molecules of life. Hydrophilic surfaces do impact water, and it has been recently shown that the impact is larger than anticipated. Surfaces...

Particles and solutes are excluded from the vicinity of hydrophilic surfaces, leaving large microsphere-free regions known as exclusion zones (EZs). Prior work had indicated that EZs could extend to distances of up to several hundred micrometers from the nucleating surface. These observations were made on large, extended surfaces, leaving open the...

The periodic bending of polyelectrolyte hydrogels made of polyacrylamide, polyacrylic and polymethacrylic acids with 10% ionization under the DC electric field was observed in 0.8 mM CaCl2. When the field with intensity 13.5 V/cm was applied perpendicular to the longitudinal axis of the gel sample, the gel first bent to cathode, then more substanti...

When a Nafion tube is immersed in water and a small hole is punched in the tube's wall, an unexpected phenomenon occurs: Water flows continuously into the tube through the hole. The phenomenon has proved repeatable, and dynamic aspects were therefore explored, including the effects of altered pH and introduction of a second hole. It appears that th...

Earlier work on particles in aqueous solution indicated that particle hydration could be expanded by incident light. To assess the effects of expanded hydration we measured Brownian displacements of microspheres exposed to light of varying intensities and wavelengths. Displacements were consistently diminished in an intensity-dependent and waveleng...

In suspensions of Nafion beads and of cationic gel beads, NMR spectroscopy showed two water-proton resonances, one representing intimate water layers next to the polymer surface, the other corresponding to water lying beyond. Both resonances show notably shorter spin-lattice relaxation times (T1) and smaller self-diffusion coefficients (D) indicati...

A physical model of the cytoskeleton based on synthetic polyelectrolyte hydrogel of polymethacrylic acid has been proposed. From the physicochemical point of view, the structures of polyelectrolyte gel and the cytoskeleton show a high degree of similarity. It was shown that polyelectrolyte gel can shorten and produce mechanical stress in response t...

The thesis offered here is that the muscle-contraction mechanism is similar to the mechanism of contraction in many artificial muscles. Artificial muscles typically contract by a phase-transition. Muscle is thought to contract by a sliding-filament mechanism in which one set of filaments is driven past another by the action of cyclically rotating c...

Recent observations have shown an unexpected feature of water adjacent to hydrophilic surfaces: the presence of wide interfacial zone that excludes solutes. The exclusion zone is charged, while the water beyond is oppositely charged, yielding a battery-like feature. The battery is powered by absorbed radiant energy. Implications of this energetic f...

Droplets of various liquids may float on the respective surfaces for extended periods of time prior to coalescence. We explored the features of delayed coalescence in highly purified water. Droplets several millimeters in diameter were released from a nozzle onto a water surface. Results showed that droplets had float times up to hundreds of millis...

Long-range attractions in aqueous suspensions were observed between polymeric microspheres and also between microspheres and a gel bead. Attractive displacements were consistently seen even between like-charged entities, and they were observed over spans as large as 2 mm. Such behaviors are unexpected, and may reside in a long-range attraction mech...

Large, solute-free interfacial zones have recently been described in aqueous solutions. Found next to hydrophilic surfaces, these "exclusion zones" are commonly several hundred micrometers wide and represent regions of water that appear to be more ordered than bulk water. We report here that other polar solvents including methanol, ethanol, isoprop...

Although it has been long known that like-charged particles attract one another in aqueous media, the mechanism underlying this counter-intuitive phenomenon has remained controversial. We tested the hypothesis put forth long ago by Langmuir and again by Feynman and by Ise, that the attraction between like-charged entities lies in an intermediate of...

While recent research on interfacial water has focused mainly on the few interfacial layers adjacent to the solid boundary, century-old studies have extensively shown that macroscopic domains of liquids near interfaces acquire features different from the bulk. Interest in these long-range effects has been rekindled by recent observations showing th...

Experiments were carried out to determine whether the newly identified "exclusion zone" found adjacent to hydrophilic surfaces might play a role in osmosis. Two chambers were juxtaposed face to face, separated by a membrane made of cellulose acetate or Nafion. One chamber contained water, the other 100 mM sodium sulfate solution. Osmotically driven...

We here examine the putative first step in the origin of life: the coalescence of dispersed molecules into a more condensed, organized state. Fresh evidence implies that the driving energy for this coalescence may come in a manner more direct than previously thought. The sun's radiant energy separates charge in water, and this free charge demonstra...

The Flory‐Huggins binary interaction parameter and its enthalpy and entropy parts were experimentally determined for polyelectrolyte hydrogels based on poly(acrylic) acid (PAAc) and poly(methacrylic) acid (PMAc) with various mono‐ and divalent counterions. It was shown that water is a poor solvent for acrylic and methacrylic polyelectrolyte hydroge...

When left overnight undisturbed in a covered beaker, suspensions of polystyrene microspheres were found to undergo a distinctive kind of macroscopically visible phase separation. Microspheres migrated radially, leaving a vertically oriented cylinder near the center of the beaker that was devoid of microspheres. Cylinder formation was preceded by fo...

Interaction between charged surfaces in aqueous solution is a fundamental feature of colloid science. Theoretically, surface potential falls to half its value at a distance equal to a Debye length, which is typically on the order of tens to hundreds of nanometers. This potential prevents colloids from aggregating. On the other hand, long-range surf...

The impact of surfaces on the contiguous water is thought to project no more than a few molecular layers from the surface. On the contrary, we have found that solutes are profoundly excluded from a several-hundred-micrometer-wide zone next to various hydrophilic surfaces, including gels. Such large ``exclusion zones'' appear to be quite general. Re...

Previous work from this and other laboratories has demonstrated large pH gradients in water. Established by passing current between immersed electrodes, pH gradients between electrodes were found to disappear slowly, persisting for tens of minutes after the current had been turned off. We find here that these pH gradients reflect a genuine separati...

Motile systems exhibit a stepwise nature, seen most prominently in muscle contraction. A novel algorithm has been developed that detects steps automatically in sarcomere-length change data and computes their size. The method is based on a nonlinear filter and a step detection protocol that detects local slope values in comparison to a threshold. Th...

Colloidal particles in suspension are excluded from the vicinity of various hydrophilic surfaces. On the basis of this phenomenon, a novel method of water purification is proposed and tested. Proof-of-concept is demonstrated using a custom-made extractor that collected clean water from the annular "exclusion zone" within a Nafion tube. Up to 99.6%...

We make the case that the unstirred layers of classical physiology arise from the influence of surfaces on the structure, and therefore the properties, of contiguous water. Traditionally, unstirred layers have been thought to arise merely out of stagnant volumes adjacent to membranes and other surfaces. These volumes would have to extend tens to hu...

Absorption and fluorescence characteristics of aqueous solutions of salts, sugars, and amino acids were studied using UV-vis spectroscopy and spectrofluorometry. Motivation stemmed from unanticipated absorption spectral and fluorescence features of the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those features implied a structur...

Colloidal crystals were formed from microsphere suspensions via a simple and novel approach using gel beads. The microspheres self-assembled not only around each bead but also between beads in an ordered pattern. The crystals shrunk under incident light, with the effect of blue (wavelength 450 to 500 nm) being the most profound. The results shed ne...

The correlation between the electrochemical (Donnan) potential and volume swelling was studied for synthetic polyelectrolyte hydrogels considered as models of cytoskeleton gel-forming biopolymers. Hydrogels involving polyacrylic and polymethacrylic acids with varying network density were synthesized by a radical polymerization in aqueous solution....

Phase transitions occur throughout nature. The most familiar example is the one that occurs in water – the abrupt, discontinuous transition from a liquid to a gas or a solid, induced by a subtle environmental change. Practically magical, the ever-so-slight shift of temperature or pressure can induce an astonishing transition from one entity to anot...

The electrical properties of water in the region between parallel electrodes were investigated using pH indicator dyes. Different pH values corresponded to different colors, which could be registered by a video camera. Imposition of electrical current was able to produce zones of constant pH around, and well beyond each electrode: extremely low pH...

Long-range interaction between polymeric surfaces and charged solutes in aqueous solution were observed microscopically. At Long-range interaction between polymeric surfaces and charged solutes in aqueous solution were observed microscopically. At low ionic strength, solutes were excluded from zones on the order of several hundred microns from the...

Donnan potentials have been measured in polyelectrolyte hydrogels gels of poly(methacr-ylic acid) and their potassium salts in water, using Ag/AgCl microelectrodes at 298 K. The Donnan potential varied from -80 to -40 mV as a function of gels’ cross-link density and the fraction of potassuim methacrylate monomer units. Negative values of the potent...

High passive stiffness is one of the characteristic properties of the asynchronous indirect flight muscle (IFM) found in many insects like Drosophila. To evaluate the effects of two thick filament protein domains on passive sarcomeric stiffness, and to investigate their correlation with IFM function, we used microfabricated cantilevers and a high r...

The cytoplasm is broadly acknowledged to be a polymer gel. Yet, textbook mechanisms build on the presumption that it is an aqueous solution. The concept of a gel-like cytoplasm is replete with power. Partitioning of ions between the inside and outside of the cell is directly explainable from the cytoplasm's gel-like character and the organization o...

It is generally thought that the impact of surfaces on the contiguous aqueous phase extends to a distance of no more than a few water-molecule layers. Older studies, on the other hand, suggest a more extensive impact. We report here that colloidal and molecular solutes suspended in aqueous solution are profoundly and extensively excluded from the v...

This book deals with the role of water in cell function. Long recognized to be central to cell function, water's role has not received the attention lately that it deserves. This book brings the role of water front and central. It presents the most recent work of the leading authorities on the subject, culminating in a series of sometimes astonishi...

The cell is known to be a gel. If so, then a logical approach to the understanding of cell function may be through an understanding of gel function. Great strides have been made recently in understanding the principles of gel dynamics. It has become clear that a central mechanism in biology is the polymer-gel phase-transition – a major structural c...

This paper considers problems with the scientific culture and granting systems, the most important of which is an aversion to risk. Grant awards tend to be "safe" rather than bold. This discourages the fresh approaches that may bring important breakthroughs. The paper then suggests remedies that could restore the scientific enterprise to one that i...

Previous experiments on thick filaments of the anterior byssus retractor muscle of Mytilus and the telson-levator muscle of Limulus polyphemus have shown large, reversible length changes up to 23% and 66% of initial length, respectively, within the physiological tension range. Using nanofabricated cantilevers and newly developed high-resolution det...

A hypothesis is proposed that the first cell(s) on the Earth assembled in a hydrogel environment. Gel environments are capable of retaining water, oily hydrocarbons, solutes, and gas bubbles, and are capable of carrying out many functions, even in the absence of a membrane. Thus, the gel-like environment may have conferred distinct advantages for t...

That the cell is a gel has been well established. If so, then a logical approach to the understanding of cell function may be through an understanding of gel function. Great strides have been made recently in understanding the principles of gel dynamics. It has become clear that a central mechanism in biology is the polymer-gel phase-transition: a...

By examining the mechanical properties of single unactivated myofibrils it has been shown that shortening and stretching of sarcomeres occurs in stepwise fashion, and that steps are seen also in the relaxed state (Yang et al. (1998) Biophys J 74: 1473-1483; Blyakhman et al. (2001) Biophys J 81: 1093-1100; Nagornyak et al. (2004) J. Muscle. Res. Cel...

The cell is a gel. This is now broadly established. If so, then a logical approach to the understanding of cell function may be through an understanding of gel function. Great strides have been made recently in understanding the principles of gel dynamics. It has become clear that a central mechanism in biology is the polymer-gel phase-transition -...

Theoretical analysis of the possibility of collapse/swelling phase transition propagation along a polyelectrolyte gel thread has been performed. A differential equation that determines the time dependence of the degree of swelling of polymer thread under the radial mechanical force has been obtained. It formally coincides with the equation of diffu...

The enthalpy of swelling over the entire concentration range in potassium polyacrylate and polymethacrylate hydrogels with varying charge density was measured by means of isothermal Calvet microcalorimetry at 298 K. Concentration plots of the enthalpy of swelling at polymer volume fractions up to 50% were used for evaluation of Flory-Huggins binary...

Cover: Partly dehydrated gels of potassium poly(acrylate) change their enthalpy as referred to maximum swollen equilibrium gel, due to the changes in molecular and ionic interactions. Microcalorimetry measurements of swelling to equilibrium for such gels reveal an enthalpy “spectrum”, which makes it possible to evaluate separately main contribution...

As the smallest muscle-cell substructure that retains the intact contractile apparatus, the single myofibril is considered the optimal specimen for muscle mechanics, although its small size also poses some technical difficulties. Myofibrils from Drosophila indirect flight muscle (IFM) are particularly difficult to study because their high passive s...