Dispersed phase morphology of impact PP copolymers. Effects of blend composition as determined by TREF

Polypropylene (PP) blends, commercially known as “impact polypropylene copolymers” (IPC), are produced by a sequential gas phase polymerization process. The final product is a complex mixture of polypropylene (PP) and a range of ethylenepropylene copolymers (EPC) with different ethylene contents. In the present work, the composition of three different IPC was estimated by performing a step elution mode Analytical Temperature Rising Elution Fractionation (TREF) separation. The recovered fractions were analyzed by Differential Scanning Calorimetry (DSC), Size Exclusion Chromatography (SEC) and Fourier Transform Infrared Spectroscopy (FTIR). The morphology was examined by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Amorphous EPC were isolated in an independent way in order to perform a more careful characterization. The distinct particle size and shape of the dispersed phase for different IPC was interpreted in terms of the molecular characteristics of the blend components and their compositions.     

Pd@Al2O3‐Catalyzed Hydrogenation of Allylbenzene to Propylbenzene in Methanol and Aqueous Micellar Solutions

The palladium on alumina (Pd@Al₂O₃)‐catalyzed hydrogenation of allylbenzene to propylbenzene was studied in methanol and aqueous micellar solutions of sodium dodecyl sulfate (SDS), decyltrimethylammonium bromide (DTAB), and t‐octylphenoxypolyethoxyethanol (TX‐100). Over Pd@Al₂O₃, propylbenzene was obtained via direct hydrogenation of allylbenzene and isomerization to β‐methylstyrene which was hydrogenated afterwards. In aqueous micellar solutions, the reaction was faster than in pure water, but slower than in methanol due to lower hydrogen solubility. In the H₂O/SDS system, a higher activation energy was obtained than in methanol. For the investigated surfactants, the initial reaction rate in the micellar systems decreased in the order SDS > TX‐100 > DTAB.     

Catalytic performance of a copper–promoted CeO2 catalyst in the CO oxidation: Influence of the operating variables and kinetic study

A study of the CO oxidation reaction was conducted on a CuO–CeO₂ catalyst, with a copper content of 20 at%. The stability, activity and selectivity of this sample were evaluated in the absence of H₂ and also under PROX conditions (i.e. in great H₂ excess). The influence of the reaction temperature and the feed composition was also analyzed. It was found that water and CO₂ have a negative effect on the catalytic activity. Except for the undesired oxidation of hydrogen, the occurrence of other lateral reactions that could be present in the PROX reactor can be discarded. A kinetic study was carried out in order to fit a classical power-law expression for CO oxidation rate. Although this mathematical expression gave a good fit in limited concentration ranges, it was found that the partial reaction orders depend on the reactant molar fractions.     

Mesoporous silica from rice hull ash

In the synthesis of mesoporous materials, the use of a template with an adequate porosity is normally favoured. As far as silica is concerned, many sophisticated procedures directed towards this goal have been published. It is already well documented that rice hull contains relatively pure silica after combustion of the residual organic matter. The authors of this contribution have recently demonstrated that large surface area silicates react with glycerol around 200 °C to give depolymerized silica with a chemical composition similar to that of poly‐alkoxides. The interest in this so‐called depolymerization is to allow easy formation of reactive gels which retain the memory of the porous structure of the original starting material. Rice hull ash (RHA), obtained after combustion of the organic residues at 500 °C, gives a silica characterized by mesopores with an average diameter about 3.5 nm. It is shown that RHA reacts with glycerol at 200 °C to form gels which, after hydrolysis and calcination, retain the mesoporous character. The hydrolysis procedure and especially, the pH is important for the distribution of the mesoporosity. The very simple reaction of a by‐product of the food industry with glycerol, a “green reagent”, gives a mesoporous solid silica in the form of a reactive gel, with many potential uses. Its use in a new procedure for the synthesis of a supported ZSM‐5 zeolite has been demonstrated. Copyright © 2007 Society of Chemical Industry     

Analysis of phenotypic variation of sugar profile in different peach and nectarine [Prunus persica (L.) Batsch] breeding progenies

BACKGROUND: Specific sugar contents are well known for contributing to a range of quality traits of fresh fruits such as flavour, texture and health properties. Peaches and nectarines of 205 genotypes from 14 different breeding progenies cultivated under Mediterranean conditions were evaluated by high‐performance liquid chromatography for their content of these sugar traits. RESULTS: A high contribution of cross to the phenotypic variance of all evaluated fruit quality traits was found. There were significant differences in mean sugar concentrations between peach and nectarine, yellow‐ and white‐fleshed or freestone and clingstone genotypes. Pre‐selected genotypes from the original breeding programme showed enhanced soluble solid content (SSC), total sugar and sucrose contents. A significant effect of year was found for SSC, sucrose and glucose contents, whereas no effect was found for fructose and sorbitol contents. Individual sugar contents correlated significantly with each other and with other fruit quality traits. CONCLUSION: A significant effect of cross, year and qualitative traits on the sugar profile of peaches and nectarines was found. Moreover, the differences shown in sugar traits between the breeding population and the pre‐selected genotypes indicated the importance of sugar profile in the global quality of peaches and nectarines. Copyright © 2009 Society of Chemical Industry     

Formulation of Corn Zein Chewing Gum and Evaluation of Sensory Properties by the Time-Intensity Method

This study was conducted to determine the feasibility of using corn zein as a natural gum base to be an alternative to the currently used synthetic gum base. The objectives were to (1) develop a corn zein chewing gum and (2) evaluate the taste, texture, and aroma qualities compared with synthetic gum base using a time‐intensity (T‐I) method. Four corn zein gum samples, each made with a different plasticizer (oleic acid, glycerin, propylene glycol, and 1 without any plasticizer), were included in the study along with 2 synthetic gum‐base samples. Nine panelists participated in the T‐I study. Thirteen attributes were evaluated. Maximum intensity, time to maximum intensity, and duration were parameters extracted from the T‐I curve. The synthetic gum‐base samples were rated higher for the maximum intensity of sweet taste and cinnamon aroma‐by‐mouth and lower for the maximum intensity of bitter taste. The propylene glycol corn zein sample was rated the highest for cinnamon aroma and the lowest for stale, rancid, and cheesy aromas. Out of the corn zein gums, the oleic acid sample was rated the lowest for the maximum intensity of hardness. It was also rated highest for the maximum intensity of bitter taste and the lowest for sweet taste. This study showed that it is feasible to use corn zein as a gum base, but future work is needed to develop an acceptable product for consumers.     

Optimization of intercooling compression in CO2 capture systems

Compression of CO₂ is an essential process in the development of carbon capture and storage (CCS) technologies. In spite of power requirements for CO₂ compression could be as much as 100 kWe per tonne CO₂, the minimization of energy requirements has received little attention in the literature. Although intercooling compression reduces power requirements, it introduces important cooling necessities that could be minimized.The aim of this paper is the integration of intercooling compression into the low-pressure part of a steam cycle to take advantage of the intercooling heat and analyse the energetic and economical results under different assumptions. Simulation and optimization have been performed in order to evaluate the intercooling configuration, energy requirements and the most cost-effective integration. Results have shown reduction in compression power requirement around 40% and reduction of the incremental COE around 23%. Proposed integration could be used to increase the efficiency of CO₂ capture processes and, therefore, to reduce the CO₂ capture cost.     

Obtaining hydroxyapatite from the exoskeleton and spines of the purple sea urchin Strongylocentrotus purpuratus

We present a simple, quick, and viable way to produce hydroxyapatite (HA) from a waste by-product of the sea food industry, this was achieved by submitting the exoskeleton of the purple sea urchin Strongylocentrotus purpuratus through a chemical reaction with H₃PO₄ at 3 different times (3, 18, and 36 hours) with constant stirring at 35-40°C. The characterization of the materials was made by several techniques (FTIR, XRD, SEM-EDS, and TEM).The FTIR results confirmed the presence of the HA characteristic functional groups OH, PO₄, and CO₃, the XRD characterization showed that the synthesis of calcium phosphates such as brushite and HA was achieved by confirming the presence of its characteristic peaks, also the EDS analysis confirmed the expected HA Ca/P atomic ratio of 1.67. This work shows that we can take advantage from raw materials derived from processing sea food by giving it an added value for the biomedical industry.     

Channeling in solid Xe, Ar and Ne direct dark matter detectors

The channeling of the ion recoiling after a collision with a WIMP changes the ionization signal in direct detection experiments, producing a larger scintillation or ionization signal than otherwise expected. We give estimates of the fraction of channeled recoiling ions in solid Xe, Ar and Ne crystals using analytic models produced since the 1960s and 1970s to describe channeling and blocking effects.