Preparation of colloidal Fe3O4 ultrafine particles in microemulsions

The preparation of magnetite particles is reported from the precipitation of Fe²⁺/Fe³⁺ with NH₄OH in several kinds of microemulsions: AOT/n-heptane/water microemulsions and a new non-toxic microemulsion system whose phase behaviour and structure has been recently studied. It is shown that both the droplet size and the presence of interactions in the dispersed phase greatly influence the final size of the obtained particles. In addition, the size of the particles can be increased by successive repetition of the reaction inside the droplets of the microemulsion.     

Development of the Multidimensional Acculturative Stress Inventory for adults of Mexican origin.

The Multidimensional Acculturative Stress Inventory (MASI), a 36-item stress measure that was developed to assess acculturative stress among persons of Mexican origin living in the United States, was tested on a community sample of 174 adults (117 women, 57 men). Principal-components analyses yielded 4 stable and internally consistent factors: Spanish Competency Pressures (7 items), English Competency Pressures (7 items), Pressure to Acculturate (7 items), and Pressure Against Acculturation (4 items). These 4 factors accounted for 64.4% of the variance and correlated in the expected directions with criterion measures of acculturation and/or psychological adjustment. Further reliability and validity testing of the MASI is discussed as well as the utility of this measure in assessing acculturative stress among adults of Mexican origin. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Modelling aquatic exposure and effects of insecticides--application to south-eastern Australia

Agricultural pesticides are widely used and can affect freshwater organisms. We applied a spatially explicit exposure model, validated for central Europe, to estimate exposure to insecticides through runoff for streams in south-eastern Australia. The model allows the identification of streams potentially affected by insecticide runoff located in 10 × 10 km grid cells. The computation of runoff relies on key environmental factors such as land use, soil texture, slope and precipitation. Additionally, the model predicted the ecological effect of insecticides on the macroinvertebrate community. We predicted insecticide surface runoff that results in a moderate to poor ecological quality for streams in half of the grid cells containing agricultural land. These results are in good accordance with the results obtained by estimating pesticide stress with a biotic index (SPEAR_pesticides) based on macroinvertebrate monitoring data. We conclude that the exposure and effect model can act as an effective and cost-saving tool to identify high risk areas of insecticide exposure and to support stream management.     

F‐actin and α‐actinin reorganization mediates initial fibroblast interaction with CoCr alloy particles in vitro

Asceptic loosening remains the primary cause for failure of joint implant. The active role of fibroblasts in mediating asceptic loosening is however not well documented. In this study the initial interactions of fibroblasts with metal particles was studied by evaluating changes in the cytoskeletal structure and cytokine level. Murine L929 fibroblasts cultured with cobalt chromium particles were observed by phase contrast and scanning electron microscopy (SEM). Changes in the cytoskeletal rearrangement of F‐actin and α‐actinin focal adhesion plaques were studied by confocal microscopy. Expression of the proinflammatory cytokines IL‐6 and IL‐1α were analyzed by ELISA. The role of actin filaments and microtubules in particle uptake were determined at low temperature and in presence of colchicine and cytochalasin B. Phase contrast and SEM studies reveal that the metal particles adhere to the fibroblasts. The cellular cytoplasm was observed to grow over the particles and is suggestive of particle uptake. Confocal microscopy shows the presence of voids within the F‐actin cytoskeletal framework corresponding to areas occupied by the metal particles, indicating the possible uptake of these particles. Aggregates of α‐actinin into patches at the cell surface were also noted. Adherence and uptake of particles did not occur at low temperature and in presence of cytochalasin B, indicating that it is an active energy‐dependent process involving actin filaments. Changes in the levels of cytokine IL‐6 and IL‐1α were not observed suggesting the role of other cytokine molecules in mediating the inflammatory response to wear debri by fibroblasts. Microsc. Res. Tech. 2012. © 2012 Wiley Periodicals, Inc.     

Simulation of time reversibility of Lamb wave in symmetric composite laminate

In this paper, a computationally efficient scheme to simulate Lamb wave propagation in symmetric laminated composite is presented and used to study time reversibility of Lamb wave. The technique proposed is a modified version of the wavelet spectral finite element (WSFE) which has been earlier developed for one- and two-dimensional wave propagation. The method follows a finite element procedure in the transformed frequency-wavenumber domain. The transformations are done using Daubechies scaling function approximation in time and one spatial dimension. Here, the modified WSFE method is used to simulate time domain Lamb wave response in doubly bounded, symmetric composite laminates. The results have been validated by comparing the wave velocities derived from these simulations with those obtained from experiments. The technique has also been used to emphasize and analyze the time reversibility phenomenon of Lamb wave. Finally, the constraint of the simulation in terms of wrap-around problem is explained with numerical examples.     

Reduced mammary tumor progression in a transgenic mouse model fed an isoflavone-poor soy protein concentrate

Dietary exposure to soy has been associated with reduced breast cancer incidence. Soy isoflavones and protein components, such as protease inhibitors and the lunasin peptide, have been indicated as potential agents reducing carcinogenesis. In this study, the effect of soy-based diets was evaluated in a transgenic mouse model of breast carcinoma, overexpressing the neu oncogene. Neu female mice were fed for 20 wk a soy- and isoflavone-free diet (IFD), 4RF21 laboratory mouse diet, soy-based, thus isoflavone-rich (STD), or AIN-76-based semisynthetic diets with a soy protein isolate (SPI) or an isoflavone-poor soy protein concentrate (IPSP) as protein source. Mice were then sacrificed and tumors removed. Mammary tumor weights were not different in SPI versus IFD and STD fed mice. In contrast, mice fed IPSP showed reduced tumor progression versus IFD and STD groups (p < 0.05). Moreover, IPSP fed mice showed lower bromo-2'-deoxyuridine (BrdU) incorporation into breast tumor cells compared to STD and SPI fed animals (p < 0.02). Lung metastases were detected in 80% of IFD fed mice, in 70% of mice fed STD and SPI, and only in 50% of the IPSP fed animals. These results indicate that a diet containing an isoflavone-poor soy protein concentrate may inhibit breast tumor progression and metastasis development.     

A generalized midpoint algorithm for the integration of a generalized plasticity model for sands

This paper describes a method of performing the integration of generalized plasticity models, in which, unlike classical elastoplasticity, the yield surface is not explicitly defined. The algorithm is based on a generalized midpoint scheme and is applied to a specific generalized plasticity model for sands, in which a hyperelastic formulation is introduced to describe the reversible component of the soil response instead of the hypoelastic approach originally proposed. In this way, an efficient integration scheme is developed in the elastic strain space. The consistent, algorithmic tangent operator is derived. Isoerror maps are generated to study the local accuracy of the numerical integration algorithm. Results from a series of numerical examples based on the simulation of drained triaxial tests are given to illustrate the accuracy and convergence properties of the algorithm, both at the local and at the global level. Finally an example is given of the simulation of a cyclic triaxial test to illustrate the improvement on accuracy caused by the use of a hyperelastic law into the constitutive equations, as opposed to the hypoelastic formulation initially adopted in the model. Copyright © 2008 John Wiley & Sons, Ltd.     

Single password authentication

Users frequently reuse their passwords when authenticating to various online services. Combined with the use of weak passwords or honeypot/phishing attacks, this brings high risks to the security of the user’s account information. In this paper, we propose several protocols that can allow a user to use a single password to authenticate to multiple services securely. All our constructions provably protect the user from dictionary attacks on the password, and cross-site impersonation or honeypot attacks by the online service providers.