Unified theoretical analysis of experimental swelling data for irradiated austenitic and ferritic/martensitic alloys

Central concepts in the theory of swelling based on defect reactions are reviewed. The critical radius and critical number of gas atoms, which determine the initiation of swelling, and the ratio of the dislocation and cavity sink strengths, which dictates the swelling rate, are demonstrated to be of great utility in the understanding and control of swelling. Over the past two decades, a large data base has been accumulated covering austenitic and ferritic/martensitic alloys, the leading candidate materials for both fusion and fast fission reactor applications. This collection of data naturally serves as the largest source of information on which to develop and test mechanistic understanding of swelling. Over wide ranges in materials and irradiation parameters, including composition, temperature, damage rate, and helium generation rate, we find that apparently divergent swelling behaviors can be explained in a unified manner within the present theoretical framework. Principles for microstructures that insure swelling resistance, together with results from the necessary confirmatory experiments, are described. This paper is based on a presentation made in the symposium “Irradiation-Enhanced Materials Science and Engineering” presented as part of the ASM INTERNATIONAL 75th Anniversary celebration at the 1988 World Materials Congress in Chicago, IL, September 25–29, 1988, under the auspices of the Nuclear Materials Committee of TMS-AIME and ASM-MSD.     

Pharmacophore Synergism in Diverse Scaffold Clinches in Aurora Kinase B

Aurora kinase B (AKB) is a crucial signaling kinase with an important role in cell division. Therefore, inhibition of AKB is an attractive approach to the treatment of cancer. In the present work, extensive quantitative structure–activity relationships (QSAR) analysis has been performed using a set of 561 structurally diverse aurora kinase B inhibitors. The Organization for Economic Cooperation and Development (OECD) guidelines were used to develop a QSAR model that has high statistical performance (R²_tr = 0.815, Q²_LMO = 0.808, R²_ex = 0.814, CCC_ex = 0.899). The seven-variable-based newly developed QSAR model has an excellent balance of external predictive ability (Predictive QSAR) and mechanistic interpretation (Mechanistic QSAR). The QSAR analysis successfully identifies not only the visible pharmacophoric features but also the hidden features. The analysis indicates that the lipophilic and polar groups—especially the H-bond capable groups—must be present at a specific distance from each other. Moreover, the ring nitrogen and ring carbon atoms play important roles in determining the inhibitory activity for AKB. The analysis effectively captures reported as well as unreported pharmacophoric features. The results of the present analysis are also supported by the reported crystal structures of inhibitors bound to AKB.     

Large intestine obstruction complicated with perforation: a rare manifestation of Schistosoma mansoni infection

The authors report a case of a 25 year old Brazilian man with a history of crampy abdominal pain in the left iliac fossa for 2 weeks, abdominal distention, mucous diarrhea and anorexia. The patient presented signs of hemodynamic instability and a hard mass palpated in the left iliac fossa presented peritoneal irritation. At laparotomy, fecal peritonitis and a punched-out perforation of the midsigmoid colon were found. A left hemicolectomy was performed with terminal colostomy. Specimen examination revealed a thickened rectosigmoid wall, narrow lumen and multiple mucosal polyps. Microscopically, chronic granulomatous colitis with Schistosoma mansoni eggs confirmed the etiology. To the authors' knowledge, this is the first case of obstruction complicated with perforation due to mansoni schistosomiasis reported in the literature.     

Papain hydrolysates of casein: molecular weight profile and encapsulation in lipospheres

Some reaction parameters were tested in the hydrolysis of casein by papain, in order to prepare hydrolysates with high oligopeptide contents, for either dietetic or pharmaceutical purposes. Five casein hydrolysates were prepared and then fractionated by size‐exclusion HPLC. The rapid correct fraction area method was used for quantifying peptides and free amino acids. Among the five reaction conditions tested, three produced similar peptide profiles. However, the use of a temperature of 37°C and an E:S ratio of 2% is probably the most economical condition for use in large‐scale manufacture. With the aim of masking the bitterness of these preparations, a new method, based on the encapsulation in lipospheres, was used. Also, second derivative spectrophotometry was used for the first time to measure the extent of encapsulation of protein hydrolysates, which changed from 50% to 83%. Moreover, the efficiency of this system was evaluated by analysing other parameters, which showed a reduction of hydrophobicity and bitterness of all samples, as well as good chemical stability during 60 days of storage under refrigeration. The electron microscopical analysis of liposheres showed an average size around 5.0 ± 1.0 µm. Copyright © 2004 Society of Chemical Industry     

Characterization of the fine fraction of the argon oxygen decarburization with lance (AOD-L) sludge generated by the stainless steelmaking industry

The argon oxygen decarburization with lance (AOD-L) sludge generated by the stainless steelmaking industry is a hazardous waste due to the presence of chromium. While its coarse fraction is usually recycled into the own industrial process, the fine fraction is normally disposed in landfills. Techniques such as briquetting or magnetic separation were found to be inadequate to treat it for reuse purposes. So, in this work, the fine fraction of the AOD-L sludge was characterized aiming to find alternative methods to treat it. This sludge consists of a fine powder (mean diameter of 1 microm) containing 34 +/- 2% (w/w) of iron, 10.2 +/- 0.9% (w/w) of chromium and 1.4 +/- 0.1% (w/w) of nickel. The main crystalline phases identified in this study were chromite (FeCr(2)O(4)), magnetite (Fe(3)O(4)), hematite (Fe(2)O(3)) and calcite (CaCO(3)). In the digestion tests, the addition of HClO(4) has favored the dissolution of chromite which is a very stable oxide in aqueous media. Nickel was found in very fine particles, probably in the metallic form or associated with iron and oxygen. The sludge was classified as hazardous waste, so its disposal in landfills should be avoided.     

Providing the stability of the coefficient of friction of a vehicle disk brake under extreme operating conditions

The authors propose a method of providing stability of the coefficient of friction of a disk brake. The method is based on the use of combination of friction materials in the force pattern of working elements of a disk brake. These friction materials interact with a brake disk and have individual level of loading. The article theoretically substantiates the possibility of the impact of the integral properties of a combination of friction materials involved in the force interaction on vehicle braking parameters. The reasonability of the proposed method is proved by the results of the experimental research. A brake-pad (lining) design has been developed to implement this method.     

Transient heat conduction by the boundary element method: D‐BEM approaches

This work is concerned with the development of different domain‐BEM (D‐BEM) approaches to the solution of two‐dimensional diffusion problems. In the first approach, the process of time marching is accomplished with a combination of the finite difference and the Houbolt methods. The second approach starts by weighting, with respect to time, the basic D‐BEM equation, under the assumption of linear and constant time variation for the temperature and for the heat flux, respectively. A constant time weighting function is adopted. The time integration reduces the order of the time derivative that appears in the domain integral; as a consequence, the initial conditions are directly taken into account. Four examples are presented to verify the applicability of the proposed approaches, and the D‐BEM results are compared with the corresponding analytical solutions.Copyright © 2011 John Wiley & Sons, Ltd.     

Optimal per cent by weight of elements in diagnostic quality radiation shielding materials

By increasing the usage of radiation in all aspects of lives, the human body is becoming more exposed to ionising radiation. The purpose of this study is to find the optimal radiation shielding materials to protect humans from the radiation hazards of radiation. Some elements and compounds such as Ag, Bi, Pb, W, BaSO(4) were chosen on the basis of their attenuation coefficients and other characteristics to produce optimised radiation shielding compounds. Multi-objective non-dominated sorting genetic algorithm-II was used to optimise the weight fraction of the elements in compounds based on the dose equivalent rate, shield weight and cost. Consequently, sets of suitable compounds were obtained depending on various applications for energy 0.06 and 0.15 MeV. In addition, optimised lead free compounds were obtained. The results presented in a series of graphs should enable radiation shield designers to choose an appropriate combination according to their requirements.