Extractant Assisted Synthesis of Polymer Stabilized Platinum and Palladium Metal Nanoparticles for Sensor Applications

Abstract

Extractant‐assisted synthesis of platinum and palladium polymer‐stabilized metal nanoparticles (PSMNP) was carried out for the first time. The synthesis included the following sequential steps: a) loading of extractant (tributyl‐phosphine oxide, TBPO) with the desired metal ion; b) preparation of a membrane “cocktail” by mixing a metal‐containing extractant, solution of the polymer (PVC or polysulfone) and plastisizer; c) membrane deposition and metal reduction inside the membrane (intermatrix synthesis of PSMNP) by using either a chemical or an electrochemical reduction technique. The electro conductivity of the resulting polymer‐metal nanocomposite membrane appeared by several orders of magnitude higher than that of the metal‐free polymer. The mass‐exchange properties of PSMNP‐containing membranes were shown to depend on both the type of the polymer and the membrane deposition technique.     

Dense nanostructured zirconia compacts obtained by colloidal filtration of binary mixtures

As starting materials two commercial nanosized zirconias doped with 3 mol% of Y₂O₃ were used: a powder of about 100 nm (TZ3YE, Tosoh, Japan) and a colloidal suspension of about 15 nm (Mel Chemicals, UK). Colloidal stability in water was studied for both zirconias in terms of zeta potential as a function of deflocculant concentration and pH. Concentrated suspensions were prepared by dispersing the powder in the colloidal suspension to solids loadings ranging from 5 to 30 vol.% using a sonication probe to achieve dispersion. The rheological behavior was optimized in terms of solids content, deflocculant content and sonication time. Optimized suspensions with up to 25 vol.% solids showed a nearly Newtonian behavior and extremely low viscosities and maintain stable for long times (days) which is an important drawback of conventional nanoparticle suspensions. Samples obtained by slip casting in plaster moulds were used for dynamic sintering studies and dense, nanostructured specimens were obtained at temperatures of 1300–1400 °C.     

Effect of a novel soy fermented product enriched with isoflavones and calcium on bone tissue of rats

The objective was to evaluate the effect of soy fermented product intake on the corporal weight and bone tissue of ovariectomized mature rats. This product was fermented with Enterococcus faecium and Lactobacillus jugurti and enriched with isoflavones and calcium. The animals were divided in 5 groups: sham-ovariectomized; ovariectomized; ovariectomized treated with soy fermented product enriched with isoflavones and calcium; ovariectomized treated with soy fermented product enriched with calcium and ovariectomized treated with non-fermented product enriched only with calcium. In order to evaluate the effect of the tested product on bone tissue (femur and tibia), the following parameters were analyzed: length; mechanical assay of three points; density (Archimedes principle); mineral content; calcium content; measure of the trabecular widths. The corporal weight of group treated with soy fermented product containing isoflavones and calcium showed no statistical difference from sham-ovariectomized group and trabecular widths tended to have larger than ovariectomized group. However, there was no significant difference to the other evaluated parameters in result of the diverse treatments. Thus, soy fermented product enriched with isoflavones and calcium inhibited the increasing of corporal weight caused by ovariectomy and revealed a tendency to trabecular protection after castration.     

Energy Efficiency of an Indirect Thermally Coupled Distillation Sequence

Several thermally coupled distillation sequences have been proposed to improve the thermal inefficiency of conventional distillation sequences. Particularly, for the separation of ternary mixtures, structures that perform a lateral extraction in one of the columns of the integrated arrangement have been shown to provide significant energy savings. The structure of existing sequences, based on conventional distillation columns, might provide the basis for alternate thermally coupled designs. In this paper, it is shown how a thermally coupled system derived from an indirect conventional sequence can provide energy savings through a proper optimization of the interconnecting streams.     

Microstructure–function relationships of heat-induced gels of porcine haemoglobin

The purpose of this work was to use image analysis to study the microstructural properties of haemoglobin gels, with structural changes induced by pH conditions, and their correlations with physical properties such as texture and water holding capacity (WHC). Two types of networks showing great differences in the dimensions of the gel structure were obtained as influenced by pH. At pH < 5.5 there was a shift from an aggregated to a fine-stranded gel type. Fractal dimension values revealed that more complex structures corresponded to softest and non-exudative gels. Lacunarity and pore size, which were used to study the pore distribution within the network, confirmed that softest gels with high WHC showed large number of small cavities. Finally, correlations between textural attributes, i.e. springiness and adhesiveness, and spatial variability, referred quantitatively to the degree of compactness, were also established.     

Water hydraulic manipulator for fail safe and fault tolerant remote handling operations at ITER

Department of Intelligent Hydraulics and Automation (IHA) of Tampere University of Technology has been involved in the European Fusion program since 1994 within the ITER reactor maintenance activities. In this paper we discuss the design and development of a six degrees of freedom water hydraulic manipulator with a force feedback for teleoperation tasks. The manipulator is planned to be delivered to Divertor Test Platform 2 (DTP2) during year 2008. The paper also discusses the possibility to improve the fail safe and redundant operation of the manipulator. During the design of the water hydraulic manipulator, special provisions have been made in order to meet the safety requirements such as servo valve block for redundant operation and safety vane brakes for fail safe operation.     

Root cause analysis during process development using Joint-Y PLS

The original purpose of the JYPLS model was to aid product transfer and scale-up. This work demonstrates that the JYPLS model is also well suited to analyze data from a process in development where the number and type of sensors and sensor locations are also being decided. The specific application in this case was to determine the root cause for a bias found during the development of a multivariate calibration model for a Near Infrared (NIR) instrument. The calibration model was built in parallel with the development of the manufacturing process itself. Each time the calibration model was tested with data from a new batch run, a non-explained bias was observed. Laboratory results on samples gathered from the process show that the NIR signal itself was biased and not the actual concentration of the constituent. Data on the processing conditions were collected for all the batches and included in the JYPLS model along with NIR and lab results. The loadings and scores from the JYPLS model were interpreted to isolate the root cause of the observed drift in the calibration model. This work discusses the general approach and presents the sequence of diagnostics used to analyze the different campaigns during process development. This should be applicable to other scenarios in process development where the data has the same architecture.     

On the efficient computation of robust regression estimators

The problem of providing efficient and reliable robust regression algorithms is considered. The impact of global optimization methods, such as stopping conditions and clustering techniques, in the calculation of robust regression estimators is investigated. The use of stopping conditions permits us to devise new algorithms that perform as well as the existing algorithms in less time and with adaptive algorithm parameters. Clustering global optimization is shown to be a general framework encompassing many of the existing algorithms.     

Centralized Modular Diagnosis and the Phenomenon of Coupling

This paper studies modular decomposition as an approach for failure diagnosis based on Discrete Event Systems. This paper also analyses the problem of coupling produced in the implementation of centralized modular diagnosers, as coupled diagnosers cannot carry out their own diagnosis task, when there is a failure in another subsystem sharing a common energy or material flow. In addition, we propose a method to avoid diagnoser coupling, by means of decoupling functions using non-local information with respect to the coupled diagnoser and generated in the diagnoser where the failure has been isolated.     

The influence of chemical treatment and suture on the elastic behavior of calf pericardium utilized in the construction of cardiac bioprostheses

Poor mechanical properties of biological tissue are known to cause wear, leading to the failure of cardiac bioprostheses made of calf pericardium. Different chemical agents such as sodium dodecyl sulfate (SDS) are presently being tested as possible inhibitors of the calcification process. The objective of this report was to determine the mechanical behavior of calf pericardium treated with SDS for 24 h and the influence of the suture on the mechanical properties of the tissue. Forty-eight samples were tested: 24 subjected to a standard treatment with glutaraldehyde (12 sewn with 4/0 silk suture thread) and 24 incubated with SDS for 24 h (12 sewn with the same suture thread). Each sutured and non-sutured sample was cut into two strips to yield paired samples. All were subjected to tensile stress to breaking point. The mean stress at breaking point in the non-sutured series treated with glutaraldehyde alone was 16.42 and 13.85 MPa depending on the region of the pericardium, while in the sutured samples subjected to glutaraldehyde the mean stress was 7.50 and 7.63 MPa, respectively, differences which were statistically significant (p = 0.03 and p = 0.003, respectively) when the means for non-sutured samples from equivalent regions treated with glutaraldehyde were compared. The stress at breaking point was lower in the SDS-treated series, ranging between 2.60 and 3.56 MPa. The mathematical functions that govern the stress/strain or deformation were obtained. In the series of pericardium treated with SDS, deformations of 10% were produced with stresses of under 0.4 MPa, an outcome that is intolerable from the constructive point of view. We established a regression model that enabled us to determine the mechanical behavior of a sutured sample by testing a contiguous piece of tissue, with a high correlation coefficient (r > 0.99). We consider this finding to be of interest in the selection of pericardium for use in the construction of leaflets for cardiac bioprostheses.