Comparison between the theoretical models and experimental structures of some octacoordinated Ln(III)-bis-dipyridyl-bis-dichloroacetato-diaquo complexes and their phenanthroline analogues

The title complexes were modeled using the semiempirical MOPAC and the newly developed SPARKLE paramerters of the lanthanides. The calculated bond distances and angles agreed well with those found from crystal structure measurements. This technique allows us to screen a large number of molecules and get structural information within a very short time.     

MECHANICAL PROPERTIES OF A FRIED CRUST*

A restructured potato model system was fried in canola oil for 5, 10, or 15 min at 170, 180, or 190C and tested in a Dynamic Mechanical Analyzer. Selected mechanical properties were measured using puncture and three‐point bending cells. Forces involved in puncture were a combination of tension, compression, and shear, while the three‐point bend test studied the crust flexural properties. Crust deformability seemed to be governed by internal structural yielding. Maximum force at rupture increased significantly with both frying time and temperature. Failure criteria identified and standardized types of failure observed during bending tests.     

Particle size and morphology of hydrothermally processed MnZn ferrites observed by atomic force microscopy

Atomic force microscopy (AFM) was employed to analyse ultrafine MnZn ferrite powders, obtained by precipitation from metal sulphates and sodium hydroxide at 110 and 190 °C, under hydrothermal conditions. Particle sizes measured on AFM images taken at the surfaces of pressed samples ranged from 10 to 40 nm, as a function of synthesis temperature, and were in good agreement with measurements made using X-ray diffraction and the Brunnauer–Emmett–Teller (BET) technique. Direct observation also showed that the particles were monodispersed and approximately spherical in shape, meeting the requirements for the production of high density sintered components. Using a straightforward sample-preparation technique, AFM proved to be a powerful tool for direct analysis of ceramic powder particles on the nanometre scale. This revised version was published online in November 2006 with corrections to the Cover Date.     

Application of interface finite elements to three-dimensional progressive failure analysis of adhesive joints

ABSTRACT The paper presents a new model for three‐dimensional progressive failure analysis of adhesive joints. The method uses interface elements and includes a damage model to simulate progressive debonding. The interface finite elements are placed between the adherents and the adhesive. The damage model is based on the indirect use of fracture mechanics and allows the simulation of the initiation and growth of damage at the interfaces without considering the presence of initial flaws. The application of the model to single lap joints is presented. Experimental tests were performed in aluminium/epoxy adhesive joints. Linear elastic and elastoplastic analyses were performed and the predicted failure load for the elastoplastic case agrees with experimental results.     

DNA mismatch repair gene methylation in gastric cancer in individuals from northern Brazil

Gastric cancer is one of the most common malignancies. DNA methylation is implicated in DNA mismatch repair genes deficiency. In the present study, we evaluated the methylation status of MLH1, MSH2, MSH6 and PMS2 in 20 diffuse- and 26 intestinal-type gastric cancer samples and 20 normal gastric mucosal of gastric cancer patients from Northern Brazil. We found that none of the nonneoplastic samples showed methylation of any gene promoter and 50% of gastric cancer samples showed at least one methylated gene promoter. Methylation frequencies of MLH1, MSH2, MSH6 and PMS2 promoter were 21.74%, 17.39%, 0% and 28.26% respectively in gastric cancer samples. MLH1 and PMS2 methylation were associated with neoplastic samples compared to nonneoplastic ones. PMS2 methylation was associated with diffuse- and intestinal-type cancer compared with normal controls. Intestinal-type cancer showed significant association with MLH1 methylation. Diffuse-type cancer was significantly associated with MSH2 methylation. Our findings show differential gene methylation in tumoral tissue, which allows us to conclude that methylation is associated with gastric carcinogenesis. Methylation of mismatch repair genes was associated with gastric carcinogenesis and may be a helpful tool for diagnosis, prognosis and therapies. However, MSH6 does not seem to be regulated by methylation in our samples.     

Numerical analysis of the ENF and ELS tests applied to mode II fracture characterization of cortical bone tissue

The objective of this work is to verify numerically the adequacy of the ENF and the ELS tests to determine the fracture toughness under mode II loading of cortical bovine bone tissue. A data‐reduction scheme based on the specimen compliance and the equivalent crack concept is proposed to overcome the difficulties inherent to crack monitoring during its growth. A cohesive damage model was used to simulate damage initiation and growth, thus assessing the efficacy of the proposed data‐reduction scheme. The influences of the initial crack length, local strength and toughness on the measured fracture energy were analysed, taking into account the specimen length restriction. Some limitations related to spurious influence on the fracture process zone of the central loading in the ENF test, and clamping conditions in the ELS test were identified. However, it was verified that a judicious selection of the geometry allows, in both cases, a rigorous estimation of bone toughness in mode II.     

ANTIBIOTIC RESISTANCE OF CAMPYLOLOBACTER ISOLATED FROM AUTOMATED BROILER FARMS

The use of the same antibiotics in animal food and conventional medicine can cause problems in the treatment of human diseases, because poultry frequently carry human pathogens. The aim of the present study was to determine the antibiotic resistances patterns of Campylobacter jejuni isolated from the rearing environment of broiler chickens – litter, drinking water, feed and the bird's cloaca. The results showed significant resistance to the following antibiotics: sulfonamide (77%), tetracycline (100%), erythromycin (80%) and penicillin G (100%). Intermediary resistance was present in bacitracin (90%), trimethoprim (100%), vancomycin (100%), chloramphenicol (97%), nalidixic acid (100%) and azithromycin (100%). However, new studies need to be carried out in Brazil to determine the resistance amplitude of this microorganism in other animals and humans. It is important to define some control strategies of the antibiotics used in animal production and human medicine.     

Cryo‐scanning x‐ray diffraction microscopy of frozen‐hydrated yeast

We developed cryo‐scanning x‐ray diffraction microscopy, utilizing hard x‐ray ptychography at cryogenic temperature, for the noninvasive, high‐resolution imaging of wet, extended biological samples and report its first frozen‐hydrated imaging. Utilizing phase contrast at hard x‐rays, cryo‐scanning x‐ray diffraction microscopy provides the penetration power suitable for thick samples while retaining sensitivity to minute density changes within unstained samples. It is dose‐efficient and further minimizes radiation damage by keeping the wet samples at cryogenic temperature. We demonstrate these capabilities in two dimensions by imaging unstained frozen‐hydrated budding yeast cells, achieving a spatial resolution of 85 nm with a phase sensitivity of 0.0053 radians. The current work presents the feasibility of cryo‐scanning x‐ray diffraction microscopy for quantitative, high‐resolution imaging of unmodified biological samples extending to tens of micrometres.