Aqueous suspensions of microspheres were infused around gels varying composition. The solutes excluded from zones on the order 100 microm gel surface. We present evidence that this finding is not an artifact, and solute-repulsion forces exist at distances far greater than conventional theory predicts. observations imply may interact over unexpectedly long range.

While recent research on interfacial water has focused mainly the few layers adjacent to solid boundary, century-old studies have extensively shown that macroscopic domains of liquids near interfaces acquire features different from bulk. Interest in these long-range effects been rekindled by observations showing colloidal and molecular solutes are excluded extensive regions next many hydrophilic surfaces [Zheng Pollack Phys. Rev. E 2003, 68, 031408]. Studies aqueous "exclusion zones" reveal...

Tension development during isometric tetani in single fibers of frog semitendinosus muscle occurs three phases: (a) initial fast-rise phase; (b) a slow-rise and (c) plateau, which lasts greater than 10 s. The phase has previously been assumed to rise out progressive increase sarcomere length dispersion along the fiber (Gordon et al. 1966. J. Physiol. [Lond.]. 184:143--169;184:170--192). Consequently, "true" tetanic tension considered be one existing before onset this is obtained by...

Absorption and fluorescence characteristics of aqueous solutions salts, sugars, amino acids were studied using UV−vis spectroscopy spectrofluorometry. Motivation stemmed from unanticipated absorption spectral features the "exclusion zone" seen adjacent to various hydrophilic surfaces. Those implied a structure distinct that bulk water (Adv. Colloid Interface Sci. 2006, 127, 19). peaks at ∼270 nm similar those observed in exclusion zone following substances: Nafion 117 solution/film,...

The use of maximum velocity shortening (V max ) as an index contractility has been based on the assumption that V muscle fibers is equivalent to contractile element. It shown here such equivalence applies two-element model skeletal but not three-element models cardiac muscle. Analysis published data in terms Voigt and Maxwell shows element, unlike fibers, independent fiber length increases at least 50% for a 25% increase length. Moreover, element seen be even more highly dependent when...

1. A fluorescent tracer dye, sodium fluorescein (mol.wt. 332), was used to assess the relative degree of intercellular coupling in various tissues rabbit heart. 2. Dye injected intracellularly by micro‐iontophoresis. Subsequent movement into contiguous cells monitored video microscopy. From these data permeability boundaries computed. 3. The values boundary were consistent with those expected from previous studies tracers whose molecular weights bracketed that fluorescein. 4. In atrium,...

Hydrophilic materials immersed in aqueous solutions show near-surface zones that exclude suspended colloids and dissolved molecules. These exclusion (EZs) can extend for tens to hundreds of micrometers from hydrophilic surfaces physicochemical properties differ bulk water. Here we report exposure standard microsphere suspensions static magnetic fields creates similar microsphere-free adjacent poles. The EZs build next both north south poles; they whether the microspheres are polystyrene or...

1. We studied the effects of shortening history on isometric force and isotonic velocity in single intact frog fibres. Fibres were isometrically tetanized. When reached a plateau, was imposed, after which fibre held again. Isometric could then be compared with controls no had taken place. 2. Sarcomere length measured simultaneously two independent methods: laser-diffraction method segment-length that detects distance between markers attached to surface fibre, about 800 microns apart. 3. The...

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 be more ordered than bulk water. We report here other polar solvents including methanol, ethanol, isopropanol, acetic acid, D(2)O, dimethyl sulfoxide (DMSO) show similar near-surface exclusion zones, albeit smaller magnitude. Microelectrode measurements...

In suspensions of Nafion beads and cationic gel beads, NMR spectroscopy showed two water-proton resonances, one representing intimate water layers next to the polymer surface, other corresponding lying beyond. Both resonances show notably shorter spin-lattice relaxation times (T1) smaller self-diffusion coefficients (D) indicating slower dynamics than bulk water. These findings confirm existence highly restricted adsorbed onto hydrophilic surfaces dynamically stable beyond first hydration...

It is generally assumed that sarcomere lengths (SLs) change in isometric fibres following activation and stretch on the descending limb of force–length relationship, because an inherent instability. Although this assumption has never been tested directly, instability SL non–uniformity have associated with several mechanical properties, such as 'creep' force enhancement. The aim study was to test directly hypothesis sarcomeres are unstable relationship. We used single myofibrils, isolated...

By examining the mechanical properties of isolated skeletal and cardiac myofibrils in calcium-free, ATP-containing solution, we attempted to separate stiffness contribution titin filaments from that weakly bound cross bridges. Efforts enhance weak cross-bridge binding by lowering ionic strength were met clear contractile responses. Even at low temperature, bathed low-ionic-strength relaxing solution generated increased force exhibited sarcomere shortening, apparently caused active...

We present two new microfabricated cantilever-beam force transducers. The transducers were fabricated from thin silicon-nitride films, and used respectively to measure forces generated by small-muscle preparations: the single myofibril, actin filament in contact with a myosin-coated surface. A simple resonance method was developed characterize Because of high reproducibility lever dimensions consistency modulus elasticity, few calibration measurements sufficed stiffness all levers on wafer.