Characterization and determination of swelling and diffusion characteristics of poly(n‐vinyl‐2‐pyrrolidone) hydrogels in water

Hydrogels in the form of rods with varying crosslink densities and three‐dimensional network structures were prepared from Poly(N‐vinyl‐2‐pyrrolidone) (PVP)/water and PVP/water/persulfate systems by irradiation with γ rays at ambient temperature. Average molecular weights between crosslinks, percent swelling, swelling equilibrium values, diffusion/swelling characteristics (i.e., the structure of network constant, the type of diffusion, the initial swelling rate, swelling rate constant), and equilibrium water content were evaluated for both hydrogel systems. Water diffusion to the hydrogel is a non‐Fickian type diffusion and diffusion coefficients vary from 6.56 × 10⁻⁷ to 2.51 × 10⁻⁷cm²min⁻¹ for PVP and 6.09 × 10⁻⁷ to 2.14 × 10⁻⁷ cm²min⁻¹ for PVP/persulfate hydrogel systems. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 994–1000, 2000     

Multi-period multi-objective electricity generation expansion planning problem with Monte-Carlo simulation

A new approach to the electricity generation expansion problem is proposed to minimize simultaneously multiple objectives, such as cost and air emissions, including CO₂ and NO_x, over a long term planning horizon. In this problem, system expansion decisions are made to select the type of power generation, such as coal, nuclear, wind, etc., where the new generation asset should be located, and at which time period expansion should take place. We are able to find a Pareto front for the multi-objective generation expansion planning problem that explicitly considers availability of the system components over the planning horizon and operational dispatching decisions. Monte-Carlo simulation is used to generate numerous scenarios based on the component availabilities and anticipated demand for energy. The problem is then formulated as a mixed integer linear program, and optimal solutions are found based on the simulated scenarios with a combined objective function considering the multiple problem objectives. The different objectives are combined using dimensionless weights and a Pareto front can be determined by varying these weights. The mathematical model is demonstrated on an example problem with interesting results indicating how expansion decisions vary depending on whether minimizing cost or minimizing greenhouse gas emissions or pollutants is given higher priority.     

Hydrogen production from the methanolysis of ammonia borane by Pd-Co/Al2O3 coated monolithic catalyst

The aim of this study is to enable high hydrogen production yield from catalytic methanolysis of ammonia borane (AB) in the presence of a cordierite type ceramic monolithic. The monolithic channel surfaces were coated with Al₂O₃ by wash-coating method and then this layer was impregnated with 1 wt%Pd-2 wt%Co bimetallic catalyst. SEM-EDX and multi-point BET analysis were used in order to characterize the catalyst. The experimental studies were conducted in a continuous flow type reactor, which was used for the first time in this study. The reactions were carried on low temperature (40 °C), and with various AB feed concentrations and flow rates. It was found that the highest hydrogen production yield (88.5%) was obtained from AB flow rate of 3.3 mL/min, and AB feed concentration of 0.1 wt%. It was concluded that Pd-Co/Al₂O₃ coated monolithic, which is a stable, active and low-cost catalyst, was a very promising catalyst for on-board hydrogen production from the methanolysis of ammonia borane.     

Sargassum swartzii extracts ameliorate memory functions by neurochemical modulation in a rat model

Food Science and Biotechnology - Recently, considerable attention has been paid to drug exploration from natural sources for treating memory loss, a major manifestation of various neurodegenerative...     

Valorization of Olive Pomace Oil with Enzymatic Synthesis of 2‐Monoacylglycerol

2‐Monoacylglycerols (2‐MAG) with a high content of oleic acid at sn‐2 position was synthesized by enzymatic ethanolysis of refined olive pomace oil, which is a byproduct of olive oil processing. Six lipases from different microbial sources were used in the synthesis of 2‐MAG. Immobilized lipase from Candida antarctica gave the highest product yield among the selected lipases. Response surface methodology was applied to optimize reaction conditions; time (4 to 10 h), temperature (45 to 60 °C), enzyme load (10 to 18 wt%), and ethanol:oil molar ratio (30:1 to 60:1). The predicted highest 2‐MAG yield (84.83%) was obtained at 45 °C using 10 (wt%) enzyme load and 50:1 ethanol:oil molar ratio for 5 h reaction time. Experiments to confirm the predicted results at optimum conditions presented a 2‐MAG yield of 82.54%. The purification yield (g 2‐MAG extracted/100 g of total product) was 80.10 and 69.00 for solvent extraction and low‐temperature crystallization, respectively. The purity of the synthesized 2‐MAG was found to be higher than 96%.     

Synthesis, electrochemistry and in situ spectroelectrochemistry of soluble lead phthalocyanines

The synthesis, characterization and voltammetric and spectroelectrochemical properties of newly synthesized lead phthalocyanines bearing tetra-(1,1-(dicarbpenthoxy)-2-(4-biphenyl)-ethyl), tetra-(1,1-(dicarbpenthoxy)-2-(1-naphthyl)-ethyl and tetra-((1,1,2-(tricarbopentoxyethyl)) substituents have been presented in this work for the first time. The characterization of the complexes was made by elemental analysis, ¹H NMR, FT-IR, UV-vis and Maldi-TOF. The solution redox properties and spectroelectrochemical investigation of the complexes are studied using various electrochemical techniques in DCM on a platinum electrode. Cyclic voltammetry and differential pulse voltammetry studies show that the complexes give three one-electron ligand-based reductions and two one-electron oxidation couples having diffusion-controlled mass transfer character. Assignments of the redox couples were confirmed by spectroelectrochemical measurements. Spectroelectrochemical studies reveal that all complexes are demetallized during the spectroelectrochemical measurement under the applied potentials at the first reduction and oxidation potentials of the complexes. Different ring substituents of the complexes affect the easy demetallization processes of the complexes.     

From heterogeneous to homogeneous nucleation of isotactic poly(propylene) confined to nanoporous alumina

The crystallization of highly isotactic polypropylene confined in self-ordered nanoporous alumina is studied by differential scanning calorimetry. A transformation from a predominantly heterogeneous to predominantly homogeneous nucleation takes place if the pore diameter is smaller than 65 nm. Crystallization is suppressed with decreasing pore size, and the absence of nucleation below 20 nm pores indicates the critical nucleus size. The results reported here might enhance the understanding of nanocomposites containing semicrystalline polymers and reveal design criteria for polymeric nanofibers with tailored mechanical and optical properties.     

Nanostructuring polymeric materials by templating strategies

This contribution summarizes efforts in designing, assembling/synthesizing, and structurally and functionally characterizing nanostructured materials using anodized aluminum oxide (AAO) as a thin-film template. Optical waveguide spectroscopy, using a nanoporous template as the guiding structure, is a particularly powerful analytical tool. The layer-by-layer approach for the fabrication of multilayer assemblies is shown to allow the fabrication of nanotube arrays. In addition to using dendrimers as building blocks, semiconducting nanomaterial (e.g., quantum dot) hybrid architectures with very interesting photophysical properties can be assembled. These can be employed, for example, in biosensing applications. Other strategies for using the AAO layers as templates include the growth of polymeric nanorod arrays from different functional monomers, which, after the dissolution of the template, are still able to guide light. This opens up novel concepts for integrated optics platforms with nanostructured materials.     

Antioxidant activities of organic grape, pomace, juice, must, wine and their correlation with phenolic content

The highest values of antioxidant activity (AOA), inhibition of low‐density lipoproteins (LDL‐diene, LDL‐MDA) and total phenols were determined in pomace (82.30 and 82.60%), grapes (68.91%) and must [2750 mg L^?1 gallic acid equivalents (GAE)], respectively. For all parameters (AOA, iLDL‐diene, iLDL‐MDA, total phenols) the highest values were obtained in Cabernet Sauvignon and Merlot grape varieties. Positive correlations were determined between AOA and iLDL‐diene (r = 0.809); AOA and total phenols (r = 0.528); total phenols and iLDL‐diene (r = 0.451) with significance of P < 0.005. The results of principal component analysis demonstrated that the location of iLDL‐diene and AOA is the same for pomace, must and red wines. The total phenols are found in the same place in red wines, red grapes, pomace and must. The results emphasize the importance of must, pomace and red wine for inhibiting LDL‐oxidation.     

Transient protein-protein interactions

Transient complexes are crucial for diverse biological processes such as biochemical pathways and signaling cascades in the cell. Here, we give an overview of the transient interactions; the importance of transient interactions as drug targets; and the structural characterization of transient protein-protein complexes based on the geometrical and physicochemical features of the transient complexes' interfaces. To better understand and eventually design transient protein-protein interactions (TPPIs), a molecular perspective of the protein-protein interfaces is necessary. Obtaining high-quality structures of protein-protein interactions could be one way of achieving this goal. After introducing the association kinetics of TPPIs, we elaborate on the experimental techniques detecting TPPIs in combination with the computational methods which classify transient and/or non-obligate complexes. In this review, currently available databases and servers that can be used to identify and predict TPPIs are also compiled.