It has been widely believed that an asymmetric GroEL-GroES complex (termed the bullet-shaped complex) is formed solely throughout the chaperonin reaction cycle, whereas we have recently revealed that a symmetric GroEL-(GroES) 2 complex (the football-shaped complex) can form in the presence of denatured proteins. However, the dynamics of the GroEL-GroES interaction, including the football-shaped complex, is unclear. We investigated the decay process of the football-shaped complex at a single-molecule level. Because submicromolar concentrations of fluorescent GroES are required in solution to form saturated amounts of the football-shaped complex, single-molecule fluorescence imaging was carried out using zero-mode waveguides. The single-molecule study revealed two insights into the GroEL-GroES reaction. First, the first GroES to interact with GroEL does not always dissociate from the football-shaped complex prior to the dissociation of a second GroES. Second, there are two cycles, the "football cycle " and the "bullet cycle," in the chaperonin reaction, and the lifetimes of the footballshaped and the bullet-shaped complexes were determined to be 3-5 s and about 6 s, respectively. These findings shed new light on the molecular mechanism of protein folding mediated by the GroEL-GroES chaperonin system.The chaperonin is an essential molecular chaperone that assists protein folding in the cell (1, 2). The Escherichia coli chaperonin GroEL is composed of 14 identical 57-kDa subunits arranged in two heptameric rings stacked back-to-back with each containing a cavity. The cofactor, GroES, consists of a dome-shaped heptameric ring of identical 10-kDa subunits.The widely accepted model of protein folding mediated by the GroEL-GroES chaperonin system is as follows. (i) The denatured protein is injected into one of GroEL rings (cis-ring) upon the ATP-dependent formation of the GroEL-GroES complex.(ii) ATP hydrolysis in the cis-ring results in the formation of the GroEL-GroES complex with bound ADP. (iii) Subsequent ATP binding to the opposite ring (trans-ring) induces the release of GroES, ADP, and the encapsulated protein from the cis-ring.(iv) The trans-ring is reoriented to a new cis-ring, thereby allowing the next ATPase cycle (1-5). In other words, an asymmetric GroEL-GroES complex (termed the bullet-shaped complex) is formed throughout the cycle, whereas a symmetric GroEL-(GroES) 2 complex (termed the football-shaped complex) does not exist.The accepted model has been challenged by the findings that indicate the existence of the football-shaped complex (6 -14). In particular, we have recently revealed that the bullet-and the football-shaped complexes coexist during the reaction cycle (14). We have also found that the formation of the footballshaped complex is regulated by the ATP/ADP ratio (14) and the amount of denatured proteins in solution (13). However, the dynamics of the GroEL-GroES interaction via the footballshaped complex remains elusive. Here, we have developed a single-molecule assay using zero-mode waveguid...

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We conducted a series of rotary‐shear friction experiments on ground dolerite gouges, in which the amount of adsorbed moisture increases with grinding time (tgr), at room temperature and humidity, a normal stress of 2 MPa, and constant equivalent slip rates (Veqs) ranging from 20 µm/s to 1.3 m/s. Their frictional strength changed with Veq and tgr in three different ways depending on Veq and the gouge temperature (T). At Veq ≤ 1.3 cm/s, T did not exceed 80°C, and the steady state friction coefficient (μss) ranged from 0.59 to 0.80. μss changes little with Veq, while μss at a given Veq systematically increases with tgr probably due to moisture‐adsorbed strengthening of gouges. At Veq = 4 cm/s, T exceeded 100°C, and dehydration of gouges resulted in roughly the same μss values (0.60–0.66) among gouges with different periods of tgr. At Veq ≥ 13 cm/s, T reached 160–500°C, and μss dramatically decreases with Veq to 0.08–0.26 at Veq = 1.3 m/s, while μss at a given Veq systematically decreases with tgr. At these fast Veqs, dehydration of gouges likely occurred too fast for water vapor to completely escape out from the gouge layer. Therefore, faster dehydration at faster Veq possibly resulted in a larger pore pressure increase and lower frictional strength. In addition, because gouges with longer periods of tgr contain larger amounts of adsorbed moisture, they became weaker due to larger increases in pore pressure and hence larger amounts of reduction in frictional strength.

In situ transmission electron microscopy (TEM) observation was carried out to clarify the aluminum single-crystallization mechanism. Aluminum filling into the grooves formed on an amorphous insulator completed at 903 K, which was 30 K below the melting point of pure aluminum. It was found that aluminum remained in the liquid state even at temperatures more than 80 K below its melting point. It is concluded that this supercooled aluminum state is essential to the fabrication of single-crystal aluminum lines, because this state enables fast solidification and suppresses polynucleations.

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