Is heat transfer governing chemical reactions in supercritical fluids?

A high pressure reactor calorimeter has been developed to study chemical reactions in supercritical fluids. Non-dimensional analysis of the heat transfer mechanism in the calorimeter verifies the application of the Nusselt correlation in scCO₂. The reactor's cover and flange have been modified to be fully temperature controlled and their contribution to the dynamic response of the calorimeter is investigated. Finally, the esterification of methanol with acetic anhydride was chosen as a model reaction and the role of heat transfer in chemical reactions in supercritical fluids is discussed.     

Improvement of reliability and dielectric breakdown strength of Nb-doped lead zirconate titanate films via microstructure control of seed

A Pb(Zr,Ti)O₃ (PZT) seed layer without Pb-deficient defective areas was developed to improve the dielectric breakdown strength and lifetime of thin film piezoelectric actuators. The proportion of defective area in the seed layers was reduced by adjusting the amount of Pb excess in the solution, combined with implementation of a dense, large-grained (>200 nm) Pt bottom electrode. The optimal Pb excess amount in the solution was about 20 at%; seeding was improved when a slightly Ti-rich composition (relative to the morphotropic phase boundary) was utilized. It was found that the dielectric breakdown strength and lifetime of PZT films improved as the proportion of visible defective area on the PZT seed layer decreased. Dielectric breakdown strength increased from approximately 300 kV/cm to about 1 MV/cm. The lifetime, characterized by highly accelerated lifetime testing, was increased 60 times by reducing the fraction of defective area. The activation energy (E_a) and voltage acceleration factor (N) for failure of devices (eg, patterned PZT films) were 1.12 ± 0.03 eV and 4.24 ± 0.07 respectively.     

Co-procurement: making the most of collaborative procurement

While the procurement decision is generally made by individual buyers, this study investigates how a group of buyers can make a shared decision. We call this collaborative approach, co-procurement. A mathematical model is formulated for the decision of procurement from multiple suppliers. The model is solved for individual buyers. The outcome shows the optimal number of items a buyer should buy from different suppliers such that the total cost is minimised for that buyer. Next, it is investigated how a group of buyers could make this decision together. The proposed model takes into account transaction costs of collaboration, to determine the optimal size of the collaboration and the involved parties. The idea is new in the old direction of procurement and it introduces the concept of transaction costs in this area and analyses its impact on the optimal collaboration size and mix. A case study from Dutch Food Valley is provided to investigate the benefits of co-procurement and validate the developed structure. The results indicate that co-procurement can bring considerable cost-savings through consolidation of orders and more efficient transportation schedules. A sensitivity analysis is conducted to determine the impact of changes in the transaction cost in favour of the co-procurement.     

Development and Validation of an ETAAS Method for the Determination of Tin in Canned Tomato Paste Samples

The determination of tin in canned food became very important in the last few years since it gives information about the contamination process helping to increase canned food quality and safety. The present work describes the development of a method for the determination of tin in canned tomato paste by electrothermal atomic absorption spectrometry in order to investigate the influents of (1) the industrial sample pretreatment procedure of canned tomato paste and (2) the type of materials used in packaging, on the total concentration of tin in canned tomato paste samples. For method validation, precision (repeatability and reproducibility) and accuracy (by recovery tests) have been assessed as performance criteria. The calculated recoveries ranged between 87.9% and 91.9%. The calculated expanded uncertainties based on the EURACHEM/CITAC Guidelines achieved from three different concentration levels were also calculated. The obtained results indicated that the method is efficiently and properly implemented. The validated method was applied for tin concentration determination in canned tomato paste purchased from the local market. In all analyzed samples, tin concentrations levels were lower than the maximum permissible value recommended by the European Regulation.     

Potential for utilizing waste corrugated paper containers into wood composites using UF and PMDI resin systems

The objective of this study was to investigate the possibility of using waste paper recovered from old corrugated containers (OCC) as substitute for wood particles in the production of particleboards. Three proportions of wood chips: waste paper flakes (100:0, 70:30, 50:50) were used in the production of one-layer and the core of three-layer experimental particleboards. Various adhesive systems were applied as binders: a UF resin (E1 grade), a PMDI resin and three UF:PMDI combinations: (6:2, 5:3 and 4:4). The evaluation of the board’s mechanical and hygroscopic properties showed the following results: Replacing woods chips with waste OCC paper adversely affected the board’s properties. The participation of waste paper in the core layer resulted in decreased differentiation between surface and core density of the boards. Partial substitution of UF resin by PMDI in amounts of 2–4?% significantly improved the properties of boards containing 30 and 50?% waste paper. An increase in board density resulted in a corresponding improvement in mechanical properties. In terms of mechanical properties, three-layer UF boards containing 30?% and PMDI bonded boards containing 30 and 50?% waste paper in the core layer complied with the requirements of European Standard EN312 for board types P1, P2 and P4 for use in interior applications.     

Cognitive and context-aware assistive environments using future internet technologies

Future Internet (FI) technologies are introducing new ways of networking and cognitive data delivery. In this paper, the potential of FI-based architectures for enabling the context-aware content adaptation and specialized delivery of health related information in assistive environments is investigated. The proposed system utilizes the publish/subscribe internetworking (PSI) architecture, an information-oriented architecture built for the FI using the so-called publish/subscribe paradigm. Information is brought at the center of the approach, providing several advantages: flexibility, seamless information morphing and exploitation of context, access control, and security in general. In addition to an overview of the approach and its characteristics, this work also presents the implementation of a subset of an assistive environment, using Blackadder, PSI’s prototype, and illustrates its potential with an emergency service scenario for the assistive healthcare domain.     

Removal of heavy metals from wastewater using CFB-coal fly ash zeolitic materials

Polish bituminous (PB) and South African (SA) coal fly ash (FA) samples, derived from pilot-scale circulated fluidized bed (CFB) combustion facilities, were utilized as raw materials for the synthesis of zeolitic products. The two FAs underwent a hydrothermal activation with 1 M NaOH solution. Two different FA/NaOH solution/ratios (50, 100 g/L) were applied for each sample and several zeolitic materials were formed. The experimental products were characterized by means of X-ray diffraction (XRD) and energy dispersive X-ray coupled–scanning electron microscope (EDX/SEM), while X-ray fluorescence (XRF) was applied for the determination of their chemical composition. The zeolitic products were also evaluated in terms of their cation exchange capacity (CEC), specific surface area (SSA), specific gravity (SG), particle size distribution (PSD), pH and the range of their micro- and macroporosity. Afterwards the hybrid materials were tested for their ability of adsorbing Cr, Pb, Ni, Cu, Cd and Zn from contaminated liquids. Main parameters for the precipitation of the heavy metals, as it was concluded from the experimental results, are the mineralogical composition of the initial fly ashes, as well as the type and the amount of the produced zeolite and specifically the mechanism by which the metals ions are hold on the substrate.     

Lipidomic Analysis of Serum from High Fat Diet Induced Obese Mice

Lipid metabolites regulate fatty acid and glucose homeostasis. The intention of the current study is to identify circulating lipid species, which are altered in rodent obesity and strongly correlate with the classically measured metabolites glucose, triglycerides, and cholesterol. Mice fed a high fat diet (HFD) for 14 weeks have increased body weight and fasting glucose. Serum triglycerides are not altered, while cholesterol tends to be increased. Accordingly, major cholesteryl ester (CE) species and free cholesterol are not significantly raised in obesity while minor metabolites, including CE 20:3 and CE 18:3, are increased or reduced, respectively. Distinct sphingomyelin (SM) species are elevated while ceramides are not raised. Phosphatidylinositol (PI) species, including PI 34:1, are raised while others are decreased. PI 34:1 strongly correlates with fasting glucose and proinsulin levels. Phosphatidylcholine (PC) 26:0, 40:2, and 40:5, which are induced in obesity, correlate with cholesterol. PC 38:4 and PC 40:6 are also raised in fat fed mice and positively correlate with fasting glucose. Lysophosphatidylcholine (LPC) species are also changed in obesity and the already shown reduction of LPC 16:1 has been confirmed. LPC 22:4, which is increased, correlates with serum cholesterol. The data indicate that circulating levels of various lipid species are changed in the obesity model studied and some of them are strongly associated with classically measured metabolites.