The Na+-pumping NADH-ubiquinone (UQ) oxidoreductase (Na+-NQR) is present in the respiratory chain of many pathogenic bacteria and is thought to be a promising antibiotic target. While many details of Na+-NQR structure and function are known, the mechanisms of action of potent inhibitors is not well understood; elucidating the mechanisms would not only advance drug design strategies but might also provide insights on a terminal electron transfer from riboflavin to UQ. To this end, we performed photoaffinity labeling experiments using photoreactive derivatives of two known inhibitors, aurachin and korormicin, on isolated Vibrio cholerae Na+-NQR. The inhibitors labeled the cytoplasmic surface domain of the NqrB subunit including a protruding N-terminal stretch, which may be critical to regulate the UQ reaction in the adjacent NqrA subunit. The labeling was blocked by short-chain UQs such as ubiquinone-2. The photolabile group (2-aryl-5-carboxytetrazole (ACT)) of these inhibitors reacts with nucleophilic amino acids, so we tested mutations of nucleophilic residues in the labeled region of NqrB, such as Asp49 and Asp52 (to Ala), and observed moderate decreases in labeling yields, suggesting that these residues are involved in the interaction with ACT. We conclude that the inhibitors interfere with the UQ reaction in two ways: the first is blocking structural rearrangements at the cytoplasmic interface between NqrA and NqrB, and the second is the direct obstruction of UQ binding at this interfacial area. Unusual competitive behavior between the photoreactive inhibitors and various competitors corroborates our previous proposition that there may be two inhibitor binding sites in Na+-NQR.

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Developments of microstructures during heating Mg85Y9Zn6 amorphous ribbons have been examined by in-situ synchrotron radiation small-and wide-angle scattering measurements. The samples show sharp crystallization peak in a DSC measurement at 450 K for a heating rate of 10K/min. During and just after crystallization, clustering occurred first within supersaturated hcp crystallites, with concomitant hcp grain growth. Above 550 K, the spatial arrangements of the cluster became anisotropic, eventually lead to 18R LPSO structures accompanied by introduction of stacking faults.

A 10-month-old female Japanese black heifer presenting with sudden loss of appetite was diagnosed with extreme extension of the gallbladder. Laparotomy reaching from the right part of the 10th rib to the right flank showed an extended gallbladder greater than 50 cm in diameter. Cholecystectomy was performed as follows: 1) complete removal of the gallbladder distally from the base; 2) flushing via a catheter inserted into the common bile duct; and 3) covering of the hole opened in the common bile duct with a double-suturing method using the mucous membrane and muscular layers of the remaining gallbladder structures. Serum levels of total bilirubin gradually decreased from 7.5 mg/dl preoperatively to 4.7 mg/dl, 1.6 mg/dl and 0.6 mg/dl at 3, 8 and 34 days postoperatively, respectively. The heifer showed 1 month of clinical improvements, grew normally and finally became pregnant. To the best of our knowledge, this represents the first clinical report to describe cholecystectomy in cattle.

An accurate value for the threshold stress intensity factor range, ΔK th , is a key parameter for studying crack-like defects. However, it is difficult to obtain accurate ΔK th values due to oxide-induced crack closure. In this study, we report conditions for minimizing the effects of oxide-induced crack closure near the threshold region, where a concave curve of the effect on the loading frequency on oxideinduced crack closure is achieved. the resulting conditions allow for an accurate determination of ΔK th , which is a key material parameter relating to the pertinent loading ratio. Almost all the mechanical structures are exposed to cyclic loading, which means that it is important to estimate the fatigue strength of mechanical structures to ensure safe operation. It is also well known that obtaining an accurate value for the threshold stress intensity factor range, ΔK th , is necessary for studying fatigue related problems. ΔK th is typically obtained via the ΔK-decreasing test based on ASTM E647 standard 1 , that the force is controlled to decrease step-by-step as the crack grows in the fatigue test, which is known to be affected by plasticity-induced 2-7 , roughness-induced 2,8-12 and oxide-induced crack closures 2,4,5,7,11,13-31. Among these types of crack closures, the roughness-induced closure is thought to be a material property because the roughness of the fracture surface is related to the microstructure of the material 10. In contrast, the plasticity-induced and the oxide-induced closures are considered to be dependent on the testing conditions 2-5,11,13-28. In order to obtain an accurate ΔK th value, these types of closures should be minimized. Many studies have been performed on the plasticity-induced closure 32-35 and have been summarized in the ASTM standard 1. The oxide-induced closure has also been studied in order to discuss the effects of various parameters 2,4,5,11,13-31. However, to the best of our knowledge, there have been no studies on the conditions that are necessary to minimize the oxide-induced closure at a low stress ratio when tested in air. According previous studies, it is considered that the large amount of oxides is generated on fracture surfaces by fretting oxidation 18 , causing the closure effect due to pushing up the crack closing point 2. Regarding the causes for the oxidation, the humidity 19,29 and the loading frequency 15,22,27,30 are important factors. Since high-moisture conditions accelerate oxidation, a low-humidity condition is recommended to minimize the oxide-induced closure. The effects of the loading frequency on the oxide-induced closure were studied by Bignonnet et al. 22 , who found that the magnitude of the closure in a structural steel at 7 Hz is smaller than that at 65 Hz. Todd et al 30. also reported a similar trend based on results from a MIL-S-24645 base metal. Conversely, Radon 36 reported that the ΔK th of an aluminium alloy tested at a high frequency tends to be smaller than that at a low frequency based on test results at 35 and 0.15 Hz. Skelton and...