Akbari H.,Isfahan University of Technology |
Karimi K.,Isfahan University of Technology |
Karimi K.,University of Bors |
Lundin M.,University of Bors |
Taherzadeh M.J.,University of Bors
Food and Bioproducts Processing | Year: 2012
Instant active dry baker's yeast is a well-known product widely used for leavening of bread, produced by fermentation, and usually dried by hot air to 94-96% dry matter content. Multi-stage fluidized bed drying process is a commercial effective method for yeast drying. In this work, optimum operating parameters of an industrial continuous fluidized bed dryer for the production of instant active dry yeast were investigated. The dryer contained four zones separated with moving weirs. The operating conditions such as temperature, loading rate of compressed yeast granules, and hot air humidity had direct effects on both yeast activity and viability. The most important factors that affected the quality of the product were loading rate and the operational temperature in each zone on the bed. Optimization was performed for three loading rates of the feed to the dryer, using response surface methodology for the experimental design. The most significant factor was shown to be the loading rate with mean fermentation activity values of 620, 652, and 646 cm 3 CO 2/h for 300, 350, and 400 kg/h loading rates, respectively. The data analysis resulted in an optimal operating point at a loading rate of 350 kg/h and temperatures of zones 1, 2, 3, and 4 controlled at 33, 31, 31, and 29 °C, respectively. The best activity value was predicted as 668 ± 18 cm 3 CO 2/h, and confirmation experiments resulted in 660 ± 10 cm 3 CO 2/h. At the same operating point, the average viability of the cells was predicted as 74.8 ± 3.7% and confirmed as 76.4 ± 0.6%. Compared with the normal operating conditions at the plant, the optimization resulted in more than 12% and 27% improvement in the yeast activity and viability, respectively. © 2011 The Institution of Chemical Engineers.
Lennartsson P.R.,University of Bors |
Lennartsson P.R.,Chalmers University of Technology |
Ylitervo P.,University of Bors |
Ylitervo P.,Chalmers University of Technology |
And 3 more authors.
Process Biochemistry | Year: 2012
The capability of two zygomycetes strains, Mucor indicus and an isolate from tempeh (Rhizopus sp.), to grow on orange peel hydrolysate and their tolerance to its antimicrobial activity, was investigated. Both fungi, in particular M. indicus, tolerated up to 2% d-limonene in semi-synthetic media during cultivation in shake flasks, under aerobic as well as anaerobic conditions. The tolerance of M. indicus was also tested in a bioreactor, giving rise to varying results in the presence of 2% limonene. Furthermore, both strains were capable of consuming galacturonic acid, the main monomer of pectin, under aerobic conditions when no other carbon source was present. The orange peel hydrolysate was based on 12% (dry w/v) orange peels, containing d-limonene at a concentration of 0.6% (v/v), which no other microorganism has been reported to be able to ferment. However, the hydrolysate was utilised by M. indicus under aerobic conditions, resulting in production of 410 and 400 mg ethanol/g hexoses and 57 and 75 mg fungal biomass/g sugars from cultivations in shake flasks and a bioreactor, respectively. Rhizopus sp., however, was slow to germinate aerobically, and neither of the zygomycetes was able to consistently germinate in orange peel hydrolysate, under anaerobic conditions. The zygomycetes strains used in the present study demonstrated a relatively high resistance to the antimicrobial compounds present in orange peel hydrolysate, and they were capable of producing ethanol and biomass in the presence of limonene, particularly when cultivated with air supply. © 2012 Elsevier Ltd. All rights reserved.
Satyanarayana K.C.,University of Bors |
Bohlen M.,University of Bors |
Lund A.,University of Bors |
Lund A.,Chalmers University of Technology |
And 2 more authors.
Polymer | Year: 2012
Analysis of the torsion angle distribution of poly(vinylidene fluoride) (PVDF) structures at temperatures above its melting point is addressed by combining first principles methods, atomistic simulations and laboratory experiments. Amorphous, α- and β-conformations of PVDF structures have been considered. The results from the atomistic simulations as well as the experiments show that there is a larger probability of the PVDF torsions to be near ±180° at temperatures above the melting point, which is associated more with the β-conformation than the α-conformation. © 2012 Elsevier Ltd. All rights reserved.
Talebnia F.,University of Bors |
Talebnia F.,Babol Noshirvani University of Technology |
Taherzadeh M.J.,University of Bors
Carbohydrate Polymers | Year: 2012
Paper tube residual was utilized as a raw material for ethanol production. The effects of two pretreatment methods namely dilute acid steam explosion (DASE) and concentrate phosphoric acid (CPA) on enzymatic hydrolysis and SSF were studied. Cellulose, lignin, glue (PVA), and xylan were the main components of paper tube accounting for 52%, 20%, 9% and 7% of dry matter, respectively. Presence of PVA delayed the growth of yeast cells but showed no effect on ultimate yield of ethanol. Higher cellulase concentration as well as pretreatments increased hydrolysis rate and ultimate yield of ethanol. Enzymatic hydrolysis of native paper tube for 72 h resulted in 49% of theoretical glucose conversion while pretreatments by DASE and CPA increased this value to 67% and 93%, respectively. The best result of SSF process was from the CPA-pretreated paper tubes with an ethanol yield of 0.42 g/g after 48 h. Under optimal condition, 308 ml ethanol per kg paper tube could be produced. © 2011 Elsevier Ltd. All rights reserved.
Jeihanipour A.,University of Bors |
Jeihanipour A.,Chalmers University of Technology |
Niklasson C.,Chalmers University of Technology |
Taherzadeh M.J.,University of Bors
Process Biochemistry | Year: 2011
Hydrolysis is widely acknowledged as the rate-limiting step in anaerobic digestion of solid cellulose to biogas (methane), and pretreatment is generally considered to facilitate the process. However, few studies have investigated how such pretreatment may affect the rest of this complex process. The present study compared the solubilization rate in anaerobic digestion of cotton linter (high crystalline cellulose), with that of regenerated cellulose (amorphous cellulose), using pretreatment with NMMO. Batch digestions were performed, with the initial cellulose concentrations ranging between 5 and 40 g/l, and during 30 days of incubation, biogas and VFAs production as well as pH and COD changes were measured. The lag time before digestion started was longer for the high crystalline cellulose than for the amorphous one. The maximum solubilization rates of treated cellulose were 842 and 517 mg sCOD/g cCOD/day at the initial cellulose concentration of 5 and 30 g/l, respectively, while the solubilization rate of untreated cellulose never exceeded 417 mg sCOD/g cCOD/day. The difference between the two cellulose types was a direct result of the high rate of hydrolysis inhibiting the acetogenesis/methanogenesis microorganisms, a drawback to the rest of the process. © 2011 Elsevier Ltd.
George G.,St Berchmans College |
George G.,Kalasalingam University |
Tomlal Jose E.,St Berchmans College |
Jayanarayanan K.,Amrita University |
And 3 more authors.
Composites Part A: Applied Science and Manufacturing | Year: 2012
This paper mainly investigates the fabrication process of jute yarn reinforced, bidirectional thermoplastic commingled composites (both untreated and treated). Commingling method was used to prepare the composites wherein the Polypropylene yarn (PP yarn) and jute yarn were wound together onto a metal plate in a particular configuration and then compression moulded. The mechanical properties of the composites prepared from chemically treated jute yarn were found to increase substantially compared to those of untreated ones. The surface morphologies of the fracture surfaces of the composites were recorded using scanning electron microscope (SEM). The SEM micrographs reveal that interfacial bonding between the treated jute yarn and the matrix has improved significantly by chemical treatments. The various chemical treatment mechanisms have been supported by FT-IR spectra. Theoretical modelling was used to predict the tensile properties and was found to be in accordance with the experimental results. © 2011 Elsevier Ltd. All rights reserved.
Moodley S.,University of KwaZulu - Natal |
Johansson E.,University of KwaZulu - Natal |
Bolton K.,University of Bors |
Ramjugernath D.,University of KwaZulu - Natal
Molecular Simulation | Year: 2012
This paper reports the effects of varying the cross-energy parameter, via a multiplying factor in each phase, on the fluid phase equilibrium compositions of a binary monatomic Lennard-Jones-based mixture (methane/xenon) using constant pressure Gibbs ensemble Monte Carlo simulations. Homogeneous () increases in within the two-phase region resulted in monotonic enrichment of methane in the liquid phase; decreasing had the opposite effect. This was valid only within a certain interval (the two-phase region) at each simulation state point because below the lower bound a single vapour phase was observed and above the upper bound a single liquid phase was observed. Homogeneous were effective at several state points for satisfactory predictions of experimental compositions. At other states, such predictions were not possible with homogeneous but it is demonstrated that perturbing the energy parameter independently in each phase () results in the experimental compositions being predicted satisfactorily. Different combinations of heterogeneous energy cross-parameters do not necessarily result in unique compositions. Variations in revealed that several minima are present on the composition error surface in the - plane and also the existence of a temperature-dependent homogeneous, which has slopes of opposite sign on either side of the critical temperature of pure methane. © 2012 Copyright Taylor and Francis Group, LLC.
Magnusson L.,University of Bors |
Magnusson L.,Linnaeus University |
Hanson E.,Corresponding Author Elizabeth Hanson |
Hanson E.,Linnaeus University |
Hanson E.,University of Sheffield
Technology and Disability | Year: 2012
ACTION (Assisting Carers using Telematics Interventions to meet Older people's Needs) stemmed from an EU-funded project (1997-2000). It is an Information and Communication Technology (ICT) based support service designed together with frail older people and their family carers to help empower them in their daily lives by providing access to web-based educational programmes, support from other ACTION families and dedicated care practitioners via the use of an integrated videophone system. It is currently running as a mainstream service in Bors municipality in West Sweden and as implementation projects in an additional twenty-five municipalities across Sweden. It is well recognised that there are relatively few examples of telecare projects that have successfully managed the transfer to a mainstream service. Based on our fourteen years of experience with the design and implementation of ACTION, we reflect on the major lessons learned. This paper highlights the user centred design model developed and refined during this period, including the range of methods for working in partnership with a variety of stakeholder groups at all stages of the technology transfer process of the ACTION service. © 2012 - IOS Press and the authors. All rights reserved.
Samadikhah K.,Chalmers University of Technology |
Larsson R.,Chalmers University of Technology |
Bazooyar F.,University of Bors |
Bolton K.,University of Bors
Computational Materials Science | Year: 2012
In the present contribution we address the modeling of graphene membranes using a hierarchical modeling strategy to bridge the scales required to describe and understand the material. Quantum Mechanical (QM) and optimized Molecular Mechanical (MM) models are used to describe details on the nanoscale, while a multiscale continuum mechanical method is used to model the graphene response at the device or micrometer scale. The complete method is obtained on the basis of the Cauchy Born Rule (CBR), where the continuum model is coupled to the atomic field via the CBR and a local discrete fluctuation field. The MM method, often used to model carbon structures, involves the Tersoff-Brenner (TB) potential; however, when applying this potential to graphene with standard parameters one obtains material stress behavior much weaker than experiments. On the other hand, the more fundamental Hartree Fock and Density Functional Theory (DFT) methods are computationally too expensive and very limited in terms of their applicability to model the geometric scale at the device level. In this contribution a simple calibration of some of the TB parameters is proposed in order to reproduce the results obtained from QM calculations. Subsequently, the fine-tuned TB-potential is used for the multiscale modeling of a nano indentation sample, where experimental data are available. Effects of the mechanical response after the calibration are demonstrated. © 2011 Elsevier B.V. All rights reserved.
Rolandsson B.,University of Bors |
Bergquist M.,Gothenburg University |
Ljungberg J.,Gothenburg University
Research Policy | Year: 2011
Opening up firms to open source has changed professional programmers' work in software development. In their work practice they must cope with two modes of software production: one based on proprietary, closed work situations, the other built around open source community ways of cooperation and knowledge sharing. In this article we present a study of how programmers cope with the co-existence of an industrial/commercial and a community/commons based mode of production. We analyze how they develop strategies to handle tensions that arise from contradictions between these two modes, and how it changes programmers' approach towards open source software development in the company. The study covers proprietary companies that have gradually incorporated open source software (hybrid companies) and SMEs entirely built around open source business concepts (pure-play companies). Four strategies are elaborated and discussed in-depth: Engineering in the lab, Market driven tailoring, Developing the community consortium and Peer-production. At a more general level, the study contributes to our understanding of how the transformation of proprietary production processes into a more open mode of knowledge work is not only associated with company strategies, but also with tensions and new demands on how work is strategically handled by knowledge workers. © 2010 Elsevier B.V. All rights reserved.