Polyelectrolytes with tetrazole pendant groups useful in the stabilization of Au and Ag nanoparticles

Stabilization of metallic nanoparticles is a challenge of enormous dimensions because the nanosize nanoparticles are not stable by themselves and therefore they tend to coalesce, forming large agglomerates causing the loss of the properties of individual nanoparticles. In this work, we report the synthesis of polyelectrolytes with tetrazole groups useful as stabilizing agents of Au and Ag nanoparticles. The polyelectrolytes with tetrazole groups were synthetized from the appropriate starting materials with nitrile groups, which were successfully converted to the corresponding 1H‐tetrazole rings using 1,3‐dipolar cycloaddition with ammonium azide. These new materials were characterized by NMR and FT‐IR techniques and they were used for the stabilization of Au and Ag colloidal nanoparticles at room temperature, using sodium borohydride as reducing agent. Formation and stabilization processes of the nanoparticles were monitored by UV‐vis spectroscopy. Shape and size of nanoparticles were studied by TEM. The polyelectrolytes with tetrazole pendant group are suitable materials for synthesis and stabilization of gold nanoparticles, obtaining average sizes lower than 10 nm. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43773.     

Degradation of Magnesium Aluminum Spinel by Lithium Fluoride Sintering Aid

The effect of LiF sintering aid on the degradation of transparent magnesium aluminate spinel during hot-pressing was studied. LiF is used to etch spinel particles during the hot pressing process. The LiF was found to react with the aluminum in the spinel structure, thereby leaving Mg-rich regions behind that do not sinter well and result in opaque white regions in the otherwise transparent matrix.     

Effect of sulphur dioxide on microbial growth in refrigerated pre-peeled potatoes packaged in plastic films

Microbial growth in pre-peeled potatoes was analysed to determine the simultaneous effect of sodium bisulphite concentration (105–219 mg kg^?1), storage temperature (4, 7 and 10°C) and gaseous permeability of the packaging plastic film (polyethylene and EVA—SARAN—EVA used in vacuum) on product storage life. Composition of the microbial flora was determined at the beginning and the end of the storage period, and the principal microorganisms causing spoilage of the product were observed to be Pseudomonas spp and Enterobacteriaceae. Lag phase duration and specific rate constants were determined for these microorganisms in samples stored at each condition. In polyethylene-packaged samples microbial growth was observed at various temperatures and SO₂ concentrations were tested. With vacuum packaging in low oxygen permeability films and residues of 100 mg SO₂ kg^?1, microbial counts were maintained in the lag phase; larger residues produced microbial inhibition at 4, 7 and 10°C.     

Resistant Starch Made from Banana Starch by Autoclaving and Debranching

Resistant starches (RS) were prepared from banana starch by debranching with pullulanase for different times and after autoclaving treatment. The different treatments produced seven RS products, which were tested with respect to available starch (AS), RS and in vitro hydrolysis rate. The control sample (without debranching) had the highest AS (80.5%) and the lowest RS content (9.1%). The samples debranched for 5 h and longer did not show significant differences (α = 0.05) in AS (approximately 72%) and RS (approximately 18%). The RS values obtained in the samples prepared were twice as high as that of the control sample. However, the sample debranched for the longest time had the highest hydrolysis rate, demonstrating that this product has a high digestion rate. Banana starch is a good source for RS preparation by autoclaving due to its high RS content and can be an alternative source in developing countries for obtaining a nutraceutic ingredient for functional food preparation.     

Application of morphological connected openings and levelings on magnetic resonance images of the brain

In this article, several advanced connected transformations from mathematical morphology for computational neuroanatomy applications are developed. In particular, brain is separated from the skull in MRI T₁ using morphological connected openings. The use of connected transformations allow the preservation of regions, without introduce new information. As a result, the segmented brains preserve by complete information of the original images being more reliable for the specialist who deals with information such as white and gray matter. © 2011 Wiley Periodicals, Inc. Int J ImagingSyst Technol, 21, 336–348, 2011     

Mechanism mediating basolateral transport of 2,4-dichlorophenoxyacetic acid in rat kidney

The organic anions, p-aminohippurate (PAH) and fluorescein, are transported across the basolateral membrane of the renal proximal tubule in exchange for intracellular alpha-ketoglutarate (alpha KG), a mechanism indirectly coupled to sodium via Na+/alpha KG cotransport. To determine whether this mechanism mediates the basolateral transport of other organic anions, transport of the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was examined in rat renal cortical slices and basolateral membrane vesicles. In slices, uptake of 2,4-D increased steadily over time, approaching steady-state tissue/medium ratios of approximately 8 after 60 min. Probenecid, PAH and chlorophenol red inhibited steady-state uptake of 2,4-D. Accumulation of 10 microM 2,4-D was stimulated 2-fold by 60 microM glutarate; other dicarboxylic acids failed to stimulate uptake. In the presence of sodium, the addition of 5 mM LiCl or 2 mM ouabain to the bathing medium abolished glutarate stimulation. Removal of sodium from the bathing medium reversibly inhibited uptake as much as 75%. Furthermore, PAH inhibited 2,4-D uptake by slices in a dose-dependent manner, and increasing the external 2,4-D concentration decreased the inhibitory potency of PAH. In basolateral membrane vesicles, unlabeled 2,4-D inhibited sodium glutarate-coupled uptake of 3H-labeled PAH and 2,4-D in a concentration-dependent manner. Moreover, concentrative uptake of 2,4-D into vesicles could be driven by an outwardly directed gradient of glutarate or alpha KG that was generated by lithium-sensitive Na+/dicarboxylate cotransport or imposed experimentally. An outwardly directed gradient of unlabeled 2,4-D or PAH also stimulated uptake of 2,4-D. Based on these data, basolateral accumulation of 2,4-D by the renal proximal tubule is mediated by 2,4-D/alpha KG exchange, a mechanism energetically coupled to Na+/alpha KG cotransport and shared with PAH.     

The experimental determination and evaluation of the three-dimensional fission density distribution of the IPEN/MB-01 research reactor facility for the IRPhE project

Experiments for the determination of the three-dimensional fission density distribution were successfully carried out at the IPEN/MB-01 research reactor facility. The experiment is of very good quality for utilization in the benchmark of computer codes and related nuclear data library commonly used for the calculation of fission density distribution in reactor cores. The complete experimental data set comprises a very massive set of measured fission density distribution. The experiment was evaluated and included in the IRPhE handbook. Two calculation methodologies were employed for the theoretical analysis of the proposed benchmark; one stochastic (MCNP-5) and the other one deterministic (NJOY/AMPX-II/TORT); both utilizing ENDF/B-VII.0 as the source of nuclear data. The theory/experiment comparison reveals in general a good agreement for both methodologies. However, MCNP-5 results are in a better shape than those of TORT. TORT underestimates the relative power distribution mainly in the axial upper part of the fuel rod. This effect is mostly credited to the over-prediction of the control bank worth.     

Oligomeric chain extenders for economic reprocessing and recycling of condensation plastics

Growth in engineering thermoplastic recycling has been slow over the past decade because the current technologies based on solid-state re-polymerization of degraded feedstock do not offer a cost advantage over the use of virgin materials. As a result, most recycling efforts focus on using degraded post-industrial or post-consumer plastics in low cost, low performance applications, such as fiber and film. To change this paradigm new technologies have been developed. However, these new technologies have not been successful because of limited property enhancement. In this work, highly tailored epoxy functional styrene-acrylic oligomers have been evaluated as chain extenders or recycling aids for condensation thermoplastics. These oligomers, when reacted in simple extrusion or injection molding equipment with virgin, post-industrial recycle or post-consumer recycled polyesters, polyamides, polycarbonates, polyurethanes, and their blends, effectively revert molecular weight degradation even at very small use levels (<1.5%). The resultant chain extended materials demonstrate mechanical and rheological properties similar to or greater than the corresponding virgin resins, at a minimal added cost. The ability of this technology to enhance properties without the need for solid-state re-polymerization, renders high end recycling economically attractive for a large number of high value added engineering applications.     

Toward an evolutionary taxonomy of treatable conditions.

The definition of disorder as a harmful dysfunction (J. C. Wakefield [see record 1999-03409-002]) is a useful concept, anchored in the recognition that the evolved human architecture consists of a collection of functional mechanisms that may potentially be impaired and whose impairment may be harmful. Because natural selection organized each mechanism to solve a distinct adaptive problem under ancestral conditions, the criteria for whether a mechanism is dysfunctional are supplied by whether the mechanism has become impaired in performing its ancestral function. Because evolutionary function and dysfunction diverge markedly from normal human standards of value, many dysfunctions are beneficial, whereas various mechanisms that are performing their evolved function may cause disturbing outcomes. For this reason, many conditions in addition to disorders may require treatment, and the authors attempt to sketch an evolutionary taxonomy of treatable conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)