Towards Ideal Magnetofluorescent Nanoparticles for Bimodal Detection of Breast‐Cancer Cells

An increasing number of novel molecular markers based on nanomaterials for tumor diagnostics have been developed in recent years. Many efforts have focused on the achievement of site‐targeted bioconjugated nanoparticles. In contrast, the mechanisms of toxicity, endocytosis, and degradation pathways are still poorly understood, despite their primary importance for clinical translation. In this study, three different model nanoscale magnetofluorescent particle systems (MFNs) are designed and fabricated. These nanoparticles are evaluated in terms of size, morphology, zeta potential, fluorescence efficiency, capability of enhancing T₂ relaxivity of water protons, and stability. Accordingly, two are developed and the mechanism of internalization, the intracellular fate, and the toxicity in MCF‐7 adenocarcinoma cells are studied. Besides the well‐documented size effect, the anionic charge seems to be a crucial factor for particle internalization, as MFN penetration through the cell membrane could be modulated by surface charge. Ultrastructural analysis of transmission electron micrographs combined with evidence from confocal microscopy reveals that MFNs are internalized by clathrin‐mediated endocytosis and macropinocytosis. Moreover, MFNs are found in EEA1‐positive endosomes and in lysosomes, indicating that they follow a physiological pathway of endocytosis. Magnetorelaxometric analysis demonstrates that MFNs enable the detection of 5 × 10⁵ cells mL^?1 after treatment with particle dosages as low as 30 µg mL^?1. Hence, MFNs appear to be a valuable and safe bimodal contrast agent that can be developed for the noninvasive diagnosis of breast cancer.     

A Simulative Model for the Analysis of Conduction Properties of Ion Channels Based on First-Principle Approaches

A physical model and a simulation framework are proposed for the analysis of conduction properties of ion channels. The permeation path of ions along the channel is defined through the simultaneous occupancy of a set of individual ion binding sites within the pore identified from structural X-ray data and Molecular Dynamics (MD) simulations. All permitted elementary transitions between different channel configurations and their rate constants can be evaluated from the atomistic structure and MD data and are implemented into a statistical model which is then coded in a Monte Carlo simulator. Results for K ions permeating the KcsA channel are shown.     

Role of biogenic amines as index of freshness in beef meat packed with different biopolymeric materials

The main objectives of this work were to evaluate the chemical and microbiological fresh beef meat quality packed in aerobic atmosphere with biopolymers, to investigate the possible role of biogenic amines (BAs) as indicators of spoilage in fresh beef meat stored at 4 °C for 8 days. The results of this research highlighted that for fresh meat packaging it could be possible to replace the PS tray/PVC film system, with an expanded PLA biopolymeric tray heat-sealed with a biopolymeric film, characterized by a negligible environmental impact in comparison with the use of synthetic plastic materials. The storage time differentiated the meat samples on the basis of pH and microbiological characteristics. With regard to BAs, tyramine and cadaverine resulted strongly influenced by the storage time, and to a less extent putrescine and spermidine. Tyramine and cadaverine could be used as spoilage indexes of fresh beef meat chilled and packed in aerobic atmosphere with biopolymers.     

Phytoplankton dynamics in two tropical rivers with different degrees of human impact (southeast Brazil)

Potamoplankton attracts little research attention worldwide and this also holds true in Brazil, despite its numerous river systems. The origin and maintenance of phytoplankton populations in these systems have not been well studied. We analysed biological, physical and chemical parameters of the Paraibuna and Pomba rivers to identify the main driving forces behind temporal and spatial phytoplankton patterns. Both systems are located in the southeast, the most populated region. These rivers are similar in climate and geomorphology, and have become eutrophic due to the increase in the human population of the region, especially in Paraibuna River catchments. Twelve and eleven stations were, respectively, sampled during the dry and rainy seasons in the Paraibuna and Pomba rivers. The seasonal pattern of abiotic and biotic variables was related to the increase in the discharge and dilution caused by the rainy period. However, human influences such as the presence of a reservoir and sewage inflow were important to distinguish the rivers. The phytoplankton community of Paraibuna River was influenced by Chapéu D'Uvas Reservoir, which was dominated by a toxic population of Cylindrospermopsis raciborskii. Pomba River phytoplankton was typical of the lotic tropical systems. Phytoplankton functional groups in both rivers were those commonly found in turbid and turbulent shallow lakes. Although the functional group approach was originally described for lentic environments, our data support this approach for lotic community patterns. Copyright © 2007 John Wiley & Sons, Ltd.     

Omega‐limit sets of a class of nonlinear systems that are semiglobally practically stabilized

In nonlinear control theory, the equilibrium of a system is semiglobally practically stabilizable if, given two balls centred at the equilibrium, one of arbitrarily large radius and one of arbitrarily small radius, it is possible to design a feedback so that the resulting closed‐loop system has the following property: all the trajectories originating in the large ball enter into the small ball and stay inside thereafter. In this work, given certain classes of nonlinear systems that are semiglobally practically stabilized, we focus on the problem of characterizing the structure of the omega‐limit set that attracts the trajectories that start inside the large ball. Copyright © 2005 John Wiley & Sons, Ltd.     

Control of magnetorheological dampers for vibration reduction in a washing machine

The aim of this work is the analysis and design of a control system for vibration and noise reduction in a washing machine. The control system is implemented via a semi-active magnetorheological (MR) damper located on the suspension that links the drum to the cabinet. The entire design procedure is outlined: first, the semi-active actuator is described and an experimental protocol is proposed and tested; two adaptive control strategies are proposed, designed and tested. Some experiments are done in an anechoic chamber to assess the noise reduction. The reported results show the effectiveness of the proposed control system.     

Textural changes during cooking of cassava (Manihot esculenta Crantz) roots

Consumer acceptability of cassava food products depends mostly on the final texture of the cooked tissue. The age of the roots at harvest seems to be an important factor in determining the final texture. Two cassava cultivars harvested at 8, 17 and 30 months after planting were used for texture loss determination by a puncture test after cooking at constant boiling water temperature. Kinetic data were analysed using fractional conversion. The raw tissue showed decreasing or constant peak yield force values as the root aged. There was a gradual first‐order softening during cooking, with decreasing rate constant as the root aged. Copyright © 2004 Society of Chemical Industry     

Processing effects on poly(ethylene terephthalate) from bottle scraps

Processing of virgin and recycled poly(ethylene terephthalate) (PET) in a twin screw extruder evidences the degradative effect caused by thermal decomposition of poly(vinyl chloride) (PVC) and other impurities, e.g. adhesives, at the processing temperature. Lower melt viscosity and molecular weight, along with higher carboxylic end group concentration, were observed for recycled PET, the extent depending on PET purity. In an attempt to investigate the correlation between the kinetics of degradation phenomena and the level of thermomechanical stress, a novel dynamic method of evaluating thermal stability in processing conditions was developed. Such a method allows the achievement of long equivalent residence times while using lab-scale extruders. As a result of these experiments, PVC-rich recycled PET was shown to reach very low melt viscosity after less than 10 min in processing conditions, while virgin PET retained high viscosity even after 30 min.