Thickness effect of notched metal sheets on deformation and fracture under tension

The deformation field in notched metal sheets stretched under tension was analysed experimentally. The results of strain distribution were explained by using the result of the near-tip deformation field of non-linear elastic material, combined with a simple model of the plastic state under a mixed plane stress and plane strain condition. Next, the relationship among fracture mechanics parameters, i.e. the notch-tip opening displacement, the notch-tip contraction and $\text{J-}\text{integral}$ was established based on the rigid plastic strip model. Finally, the effect of the specimen thickness on the toughness value at crack initiation and instability was discussed by improving Bluhm's idea that the total fracture resistance was the sum of the fracture work for slant and flat fractures.     

Simulations of reversible protein aggregate and crystal structure

We simulated the structure of reversible protein aggregates as a function of protein surface characteristics, protein-protein interaction energies, and the entropic penalty accompanying the immobilization of protein in a solid phase. These simulations represent an extension of our previous work on kinetically irreversible protein aggregate structure and are based on an explicit accounting of the specific protein-protein interactions that occur within reversible aggregates and crystals. We considered protein monomers with a mixture of hydrophobic and hydrophilic surface regions suspended in a polar solvent; the energetic driving force for aggregation is provided by the burial of solvent-exposed hydrophobic surface area. We analyzed the physical properties of the generated aggregates, including density, protein-protein contact distributions, solvent accessible surface area, porosity, and order, and compared our results with the protein crystallization literature as well as with the kinetically irreversible case. The physical properties of reversible aggregates were consonant with those observed for the irreversible aggregates, although in general, reversible aggregates were more stable energetically and were more crystal-like in their order content than their irreversible counterparts. The reversible aggregates were less dense than the irreversible aggregates, indicating that the increased energetic stability is derived primarily from the optimality rather than the density of the packing in the solid phase. The extent of hydrophobic protein-protein contacts and solvent-exposed surface area within the aggregate phase depended on the aggregation pathway: reversible aggregates tended to have a greater proportion of hydrophobic-hydrophobic contacts and a smaller fraction of hydrophobic solvent-exposed surface area. Furthermore, the arrangement of hydrophobic patches on the protein surface played a major role in the distribution of protein contacts and solvent content. This was readily reflected in the order of the aggregates: the greater the contiguity of the hydrophobic patches on the monomer surface, the less ordered the aggregates became, despite the opportunities for rearrangement offered by a reversible pathway. These simulations have enhanced our understanding of the impact of protein structural motifs on aggregate properties and on the demarcation between aggregation and crystallization.     

Spontaneous haemothorax associated with von Recklinghausen's disease: review of occurrence in Japan

The case history is presented of a 61 year old man with von Recklinghausen's disease who developed a spontaneous haemothorax. In spite of being asymptomatic for five days after drainage, he died as a result of fatal sudden re-bleeding. The post mortem examination showed dissection and rupture of the left subclavian artery. Microscopically, disarrangement of smooth muscle and decrease of elastic fibre was observed in the ruptured artery. Haemothorax in patients with von Recklinghausen's disease may require thoracotomy, even if the condition of the patient appears to be stable.     

Phase I safety and pharmacokinetic studies of brequinar sodium after single ascending oral doses in stable renal, hepatic, and cardiac allograft recipients

Brequinar sodium (BQR), a substituted 4-quinoline carboxylic acid, was in clinical development in combination with cyclosporine (CsA) as a potentially effective therapy for the treatment and prophylaxis of rejection in organ transplant patients. This phase I study was performed in stable renal, hepatic, and cardiac transplant patients receiving CsA and prednisone maintenance therapy for immunosuppression. The pharmacokinetic objectives of this study were to characterize the pharmacokinetics of (a) single oral 0.5- to 4-mg/kg doses of BQR when given in combination with CsA and prednisone to stable renal, hepatic, and cardiac transplant patients and (b) steady-state oral doses of CsA, with and without single oral doses of BQR. In all three patient populations, the pharmacokinetics of BQR were characterized by a lower oral clearance (12-19 mL/min) than that seen in previous studies in patients with cancer (approximately 30 mL/min at similar doses) and a long terminal half life (13-18 hrs). This slower oral clearance for BQR could be due either to a drug interaction between BQR and CsA or to altered clearance or metabolic processes in patients with transplants. Steady-state CsA trough levels and the oral clearance of CsA were not affected by BQR coadministration. Among the three transplant populations, the cardiac transplant patients had lower oral clearance values of BQR and of CsA. The cause of this lower clearance is not known. Safety results indicate that BQR was well tolerated by this patient population.     

Development of thick wall 2.25Cr-1MoNiNb steel forgings for steam generators of fast breeder reactors

The large and thick forgings made of 2.25Cr-1MoNiNb steel are required for vessel material of steam generator (SG) of the fast breeder reactor SNR 300.In order to study the feasibility of 2.25Cr-1MoNiNb steel heavy section forging, chemical composition, melting practice and ingot making, hot working and heat treatment conditions were investigated. The following recommendations were derived: (1) 0.04% C, 0.10% ΔNb, (2) application of electro-slag remelting process, (3) grain refining by hot working, (4) two-step austenitizing at 1020°C.Based on these recommendations, the actual products such as hollow cylinders with maximum 290 mm thickness, solid bars with 420 mm diameter and forged plates with maximum 185 mm thickness could be supplied for application in the helical coiled SG of the SNR 300. Statistical analysis of the products showed the sufficient and isotropic material properties, which fulfill the requirements of the basic safety rules.     

The ATP synthase of Trypanosoma brucei is developmentally regulated by an inhibitor peptide

The Trypanosoma brucei ATP synthase, like those of other organisms, is composed of two moieties, the membrane bound F0 and the catalytic F1 with each of these parts comprised of multiple subunits. In addition, an endogenous inhibitor peptide of the ATP synthase has been identified from a variety of sources. Previous reports have suggested that the Trypanosoma brucei ATPase may not possess such an inhibitor. Recently, we have isolated an inhibitor peptide fraction from the procyclic form of Trypanosoma brucei by modification of a previously published procedure. This fraction is composed of two dominant polypeptides with estimated molecular weights of 14,000 and 12,000 and an additional polypeptide of 15,000 that may or may not be functionally required. Antibodies raised to the smallest polypeptide showed strong cross reactivity with the other two polypeptides, suggesting that they are related. Antibodies to rat liver inhibitor peptide show cross reactivity with the same polypeptides in crude fractions. The inhibitor peptide fraction strongly suppresses the ATPase activity of membrane bound ATPase in a Mg(2+)-dependent manner and is cold and heat stable. Using antibodies to the smallest polypeptide and rat liver inhibitor peptide we have shown in crude extracts from the three experimental life cycle stages of T. brucei that the inhibitor peptide(s) is developmentally regulated to a modest extent. The pattern of regulation is opposite of the pattern seen for the ATP synthase complex. This suggests that the ATP synthase is stringently controlled in T. brucei in a unique way.