Effect of acid treatment on the physicochemical and structural characteristics of starches from different botanical sources

Starch and starch derivatives (maltodextrins) are used as encapsulating materials. Starch for use as encapsulating material could be subjected to mild acid treatment. However, the granule size and organization of starch components (AM and AP) play an important role in the acid treatment. The aim of this research was to produce modified starch that might be used as encapsulate material, applying moderate acid‐treatment with 3 N sulphuric acid in a ratio 1:5 w/v for 3 h at 60°C, in starches from different granule size, evaluating their morphological, physicochemical, and structural features. Acid treatment has an effect in the AM content and the outcome was higher in starch with larger granule size. Bimodal granule size distribution was found in acid‐treated rice and maize starches. Erosion and exo‐corrosion were observed in acid‐treated starches with SEM. The XRD pattern did not change with the acid treatment, the native and acid‐treated samples showed similar crystallinity values, except rice starch. The branching degree was higher for modified potato starch, showing higher branching points, modified starches had shorter chains with increased A‐chains, and decreased B3+ chains, and the effect was higher in cereal starches; modified starches had a higher degree of retrogradation and they did not show pasting properties. The internal organization given by the granule size is an important parameter in the acid treatment of starches as it affected their physicochemical and structural features, and in the end, their functionality as encapsulate agent.     

Starch properties of malted barley in relation to real degree of fermentation

Real degree of fermentation (RDF) is an important measure of brewhouse performance in the production of beer. In this work, the relationship of RDF with malted barley starch properties was investigated. Starches were isolated from 25 malted barley samples and analyzed for molecular size distribution (by HPSEC), AP structural features (by high‐performance size exclusion chromatography with multi‐angle laser light scattering and RI detectors), and thermal properties (by DSC). Cluster analysis, analysis of variance, principal component analysis, bivariate correlation, and multiple linear regression analysis were used in establishing correlations. RDF, AM, and AP content were 74.0–80.1%, 25.2–34.4%, and 65.6–74.9%, respectively. Starch gelatinization enthalpy was 6.4–8.1 J/g, and onset gelatinization temperature was 58.5–64.3°C. AP and AM content had a positive and negative impact on RDF, respectively. The effect of thermal properties (starch gelatinization and AM‐lipid complex melting) on RDF was not clear. Starch properties explained up to 86% of RDF variance to indicate that other malted barley constituents and/or properties also contribute to cultivar variations in RDF.     

Graphene-graphite oxide field-effect transistors

Graphene's high mobility and two-dimensional nature make it an attractive material for field-effect transistors. Previous efforts in this area have used bulk gate dielectric materials such as SiO(2) or HfO(2). In contrast, we have studied the use of an ultrathin layered material, graphene's insulating analogue, graphite oxide. We have fabricated transistors comprising single or bilayer graphene channels, graphite oxide gate insulators, and metal top-gates. The graphite oxide layers show relatively minimal leakage at room temperature. The breakdown electric field of graphite oxide was found to be comparable to SiO(2), typically ~1-3 × 10(8) V/m, while its dielectric constant is slightly higher, κ ≈ 4.3.     

Photonic density of states maps for design of photonic crystal devices

In this work, it has been investigated whether photonic density of states maps can be applied to the design of photonic crystal-based devices. For this reason, comparison between photonic density of states maps and transmittance maps was carried out. Results of comparison show full correspondence between these characteristics. Photonic density of states maps appear to be preferable for the design of photonic crystal devices, than photonic band gap maps presented earlier and than transmittance maps shown in the paper.     

Congestion management and transmission rights in centralized electric markets

A new congestion management system is proposed, applied under nodal and zonal dispatches with implementation of fixed transmission rights (FTR) and flowgate rights (FGR), respectively. The FTR model proves to be especially suitable for congestion management in deregulated centralized market structures with nodal dispatch, while the FGR is suitable for decentralized markets. The main contribution of this work is a nontraditional valuation of FGR under a centralized market, such as those present in Latin America, that builds a link between both transmission rights under the same market structure. To accomplish that, a computational model is developed, implementing marginal theory where congestion components are introduced in the pricing model. An application to the Chilean Central Interconnected System indicates that FGR presents advantages over FTR regarding signals on grid use, but its application results in complications that make its implementation unattractive.     

Disinfection kinetics of pathogens in physicochemical sludge treated with ammonia.

Ammonia is a disinfectant which can diffuse through the membrane of highly resistant structures like helminth ova. Thus, it can be considered an alternative disinfectant of wastewater sludge with high pathogenic content. In this study, the kinetic parameters of the Hom model were used to describe the inactivation with ammonia of faecal coliforms, Salmonella spp. and viable helminth ova. These were obtained in processes considering the addition of ammonia alone as well as for ammonia combined with an increase in temperature. The sludge was sampled from a municipal wastewater treatment plant using an APT (Advanced Primary Treatment) or CEP (Chemical Enhanced Primary) process. With 20% w/w of ammonia, 7 logs of faecal coliforms, 6 logs of Salmonella spp., and 83% of viable helminth ova were reduced in 2 hours contact time. To eliminate 100% of the helminth ova from samples having 88-132 ova/g TS it was needed to combine 20% of ammonia with 50 degrees C. The analysis of parameters k, n and m indicate higher resistance to inactivation of helminth ova compared to bacteria and a better performance of the ammonia process than lime stabilization to inactivate microorganisms. In addition, ammonia increased the agricultural value of the biosolids produced.     

A validation study of the Penn Interactive Peer Play Scale with urban Hispanic and African American preschool children.

Investigated the psychometric properties of a Spanish and English version of the Penn Interactive Peer Play Scale (PIPPS) when employed with Spanish- and English-speaking teachers and students in an urban, Southeastern community. Psychometrically sound structures were obtained with the Spanish translation of the PIPPS in support of the three original dimensions named Play Interaction, Play Disruption, and Play Disconnection, which were derived from studies of African American preschool children in lower income, Northeastern communities. Concurrent validity was supported by significant correlations between the 3 Spanish PIPPS constructs and teacher ratings of externalizing and internalizing behavior problems. Significant group differences in classroom peer play interactions were also detected for children's gender and ethnicity. The independent emergence of comparable Spanish and English PIPPS factor structures across 2 distinct regional samples provides initial support for use of this measure in research with Hispanic preschool children from low-income backgrounds. Implications for school psychologists engaging in outreach to preschool programs servicing diverse groups of children are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)