Microkinetic model for the pyrolysis of methyl esters: From model compound to industrial biodiesel

A tool for the generation of decomposition schemes of large molecules has been developed. These decomposition schemes contain radicals which can be eliminated from the model equations if both the μ‐hypothesis and the pseudosteady‐state approximation are valid. The reaction rate coefficients and thermodynamic parameters have been calculated by incorporating a comprehensive group additive framework. A microkinetic model for the pyrolysis of methyl esters with a carbon number of up to 19 has been generated using this tool. It is validated by comparing calculated and experimental yields of the pyrolysis of methyl decanoate and novel rapeseed methyl ester pyrolysis data in the temperature range from 800 to 1100 K and methyl ester partial pressure range from 1 × 10^?3 to 1 × 10^?2 MPa. This modeling frame work allows to not only assess the use of methyl ester mixtures as potential feedstock for olefin production but also their effect as blend‐in or trace impurity. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4309–4322, 2015     

Dietary intakes and food sources of fatty acids for Belgian women, focused on n-6 and n-3 polyunsaturated fatty acids

The intake of fat, saturated and monounsaturated FA (SFA and MUFA), and omega-6 and omega-3 PUFA has been estimated in 641 Belgian women (age 18-39 y). Their food intake was recorded using a 2-d food diary. The PUFA included were linoleic (LA), alpha-linolenic (LNA), arachidonic (AA), eicosapentaeonoic (EPA), docosapentaenoic (DPA) and docosahexaenoic (DHA) acids. The mean total fat intake corresponded to 34.3% of total energy intake (E). The mean intake of the FA groups corresponded to 13.7%, 13.1%, and 6.0% of E, for SFA, MUFA, and PUFA, respectively. The mean intake of LA was 5.3% of E and of LNA was 0.6% of E, with a mean LA/LNA ratio of 8.7. The mean intake of AA was 0.03% of E. The mean intake of EPA, DPA, and DHA was 0.4%, 0.01%, and 0.06% of E, respectively. According to the Belgian recommendations, the total fat and SFA intake was too high for about three-quarters of the population. The mean LA and overall n-6 PUFA intake corresponded with the recommendation, with part of the population exceeding the upper level. Conversely, the population showed a large deficit for LNA and n-3 PUFA. The major food source for LA and LNA was fats and oils, followed by cereal products. The main sources of long-chain PUFA were fish and seafood, and meat, poultry, and eggs. From a public health perspective, it seems desirable to tackle the problem of low n-3 PUFA intake.     

Irradiation gamma d'échantillons d'amidon contaminés par des sporulés anaérobies

Gamma Irradiation of Starch Samples Contaminated with Anaerobic Germs . Of the starch samples examined only a small part contained spores of mesophilic Clostridia. None of the samples showed signs of presence of rigidly thermophilic varieties and of Clostridium botulinum or Clostridium perfringens. 14 groups of germs were isolated from the dry products of starch industry. At least one germ group showed an activation phenomenon and a probable survival rate of 300% at 75 krad. This is true for the germ group which appears most frequently with starch and can be identified as Clostridium sporogenes. Gamma irradiation does not neutralize lysozyme dependence of the Clostridium perfringens germ which has this property. With a few reservations the standards for germ content which have been set for Bacillus spores can be also used for Clostridium spores.     

Performance of Sulfate-reducing Passive Bioreactors for the Removal of Cd and Zn from Mine Drainage in a Cold Climate

Mine Water and the Environment - Passive treatment is a promising, green technology that is increasingly being used for mine drainage treatment. However, several challenges remain concerning its...     

Understanding web site redesigns in small- and medium-sized enterprises (SMEs): a U.K.-based study on the applicability of e-commerce Stage Models

Despite the efforts of governments and the various support programmes, achievement of advanced stages of e-commerce by small- and medium-sized enterprises (SMEs) is still very low. There have been some attempts to study the dynamic nature of websites, but there is still little research evidence to explain why and how SMEs evolve their web presence. This paper aims to develop a comprehensive classification of drivers for web site redesign based on interviews with various members of staff from SMEs in the U.K. that have recently redesigned their web sites. A sequential mixed-methodological analysis, involving the use of qualitative and quantitative data analysis, was used to develop the classification. This enabled the development of a framework that classified seven main categories of drivers for web site redesign. The drivers identified were: changing business requirements, evolving internet strategies, addressing user needs, maintenance, changing technology, pressure from peers/competitors, and the influence of developers. However, only the first four were found to be significant in the study. The categorisation and the findings suggest a number of key determinants not explicitly addressed by other work. In addition, the findings provide little support for the staged approach to e-commerce progression as few companies reported the implementation of sophisticated internet technology features as a main reason for their web site redesigns. The contributions of this paper are firstly, to provide an instrument to the academic and practitioner communities interested in the topic of web site evolution. Secondly, the categorisation of drivers for redesign and the individual reasons found in this study are expected to provide assistance to SME managers to justify, plan and strategise internet investments realistically and effectively.     

BEM analysis of damage progress in 0/90 laminates

The massive use of composites in primary structures of modern commercial aeroplanes is leading to the need for profound knowledge of the mechanisms of damage and failure of heterogeneous materials of this type. This knowledge requires a very fine evaluation of the stress state, which in turn is needed to calculate the parameters of fracture mechanics used to evaluate the integrity or damage tolerance of a particular component. In this paper, the initiation and growth of the damage in a typical [0/90]_S laminate is investigated. Using a BEM code allowing contact between the lips of interfacial cracks appearing in the damaged configuration and based on a former generalized plane strain formulation of the problem developed by the authors, the energy release rate (ERR) is calculated for different configurations corresponding to the different intermediate states that may occur in the process of damage generation. The numerical results obtained clarify some aspects of the progression of the damage and open up the possibility, using comparison with experimental results, of understanding, and consequently improving, the performance of composite materials.     

Assigning multiple activities to work shifts

In some companies such as large retail stores, the employees perform different activities (e.g., cashier or clerk in a specific department) to respond to a customer demand for each activity that varies over the planning horizon and must be fulfilled as soon as possible. For a given time period, this demand translates into an ideal number of employees required for the corresponding activity. During a work shift, an employee can be assigned to several activities that are interruptible at any time and subject to operational constraints (required skills, minimum and maximum assignment durations). Given work shifts already assigned to the employees, the multi-activity assignment problem (MAAP) consists of assigning activities to the shifts such that the activity demands are satisfied as best as possible over the planning horizon. In this paper, we propose three integer programming models for the MAAP and develop various heuristics based on mathematical programming techniques. Computational results obtained on randomly generated MAAP instances show that a heuristic column generation method embedded into a rolling horizon procedure provides the best results in general.     

Electronic System to Obtain Directly the Electrochemical Charges in the Multipulse Potentiodynamic Technique

SUMMARY

A digital readout system to obtain automatically the anodic or cathodic charges in electrochemical reactions by the multipulse potentiodynamic technique is presented. The cathodic charge of the hydrogen deposition is determined in 1N H₂SO₄ in the absence and presence of 1M methanol on a platinum electrode to Illustrate the possibilities of the Instruments.