Collective behaviour in a square lattice of driven Duffing resonators coupled to van der Pol oscillators

The global and local synchronisation of a square lattice composed of alternating Duffing resonators and van der Pol oscillators coupled through displacement is studied. The lattice acts as a sensing device in which the input signal is characterised by an external driving force that is injected into the system through a subset of the Duffing resonators. The parameters of the system are taken from MEMS devices. The effects of the system parameters, the lattice architecture and size are discussed.

Nonlinear dynamics of a periodically driven Duffing resonator coupled to a Van der Pol oscillator

We explore the dynamics of a periodically driven Duffing resonator coupled elastically to a van der Pol oscillator in the case of 1?:?1 internal resonance in the cases of weak and strong coupling. Whilst strong coupling leads to dominating synchronization, the weak coupling case leads to a multitude of complex behaviours. A two-time scales method is used to obtain the frequency-amplitude modulation. The internal resonance leads to an antiresonance response of the Duffing resonator and a stagnant response (a small shoulder in the curve) of the van der Pol oscillator. The stability of the dynamic motions is also analyzed. The coupled system shows a hysteretic response pattern and symmetry-breaking facets. Chaotic behaviour of the coupled system is also observed and the dependence of the system dynamics on the parameters are also studied using bifurcation analysis.

Employability and the psychological contract in European ICT sector SMEs

This article explores the employability of information and communication technology (ICT) professionals from the perspective of small- and medium-sized enterprises (SMEs). The first stage of analysis, based on over 100 interviews with managers of ICT supplier companies in seven European countries (Germany, Greece, Italy, the Netherlands, Norway, Poland and the UK), showed most SMEs to have a generally ad hoc approach to managing the employability of their ICT professionals. Assessment and development plans were used primarily to keep skills current to business needs; however, the more developed northern European markets showed greater awareness of the ‘high commitment’ benefits of a more sophisticated approach towards career management (e.g. through mentoring or career planning). A second stage of analysis based only on UK interviews builds on this to propose a model of positive employer influence on psychological contracts through career and employability management practices.

Minimum description length, regularisation and multi-modal data

Conventional feed forward Neural Networks have used the sum-of-squares cost function for training. A new cost function is presented here with a description length interpretation based on Rissanen's Minimum Description Length principle. It is a heuristic that has a rough interpretation as the number of data points fit by the model. Not concerned with finding optimal descriptions, the cost function prefers to form minimum descriptions in a naive way for computational convenience. The cost function is called the Naive Description Length cost function. Finding minimum description models will be shown to be closely related to the identification of clusters in the data. As a consequence the minimum of this cost function approximates the most probable mode of the data rather than the sum-of-squares cost function that approximates the mean. The new cost function is shown to provide information about the structure of the data. This is done by inspecting the dependence of the error to the amount of regularisation. This structure provides a method of selecting regularisation parameters as an alternative or supplement to Bayesian methods. The new cost function is tested on a number of multi-valued problems such as a simple inverse kinematics problem. It is also tested on a number of classification and regression problems. The mode-seeking property of this cost function is shown to improve prediction in time series problems. Description length principles are used in a similar fashion to derive a regulariser to control network complexity.

Transition in inclined internally heated fluid layers

Non-linear solutions and studies of their stability are presented for flows in a homogeneously heated fluid layer under the influence of a constant pressure gradient or when the mass flux across any lateral cross-section of the channel is required to vanish. The critical Grashof number is determined by a linear stability analysis of the basic state which depends only on the z-coordinate perpendicular to the boundary. Bifurcating longitudinal rolls as well as secondary solutions depending on the streamwise x-coordinate are investigated and their amplitudes are determined as functions of the supercritical Grashof number for various Prandtl numbers and angles of inclination of the layer. Solutions that emerge from a Hopf bifurcation assume the form of propagating waves and can thus be considered as steady flows relative to an appropriately moving frame of reference. The stability of these solutions with respect to three-dimensional disturbances is also analyzed in order to identify possible bifurcation points for evolving tertiary flows.

Solvent induced NMR chemical shifts that arise from molecular encounters

Recently Homer and Percival have postulated that intermolecular van der Waals dispersion forces can be characterized by three mechanisms. The first arises via the mean square reaction field < R1; 2> due to the transient dipole of a particular solute molecule that is considered situated in a cavity surrounded by solvent molecules; this was characterized by an extended Onsager approach. The second stems from the extra cavity mean square reaction field < R2; 2> of the near neighbour solvent molecules. The third originates from square field electric fields E2BI due to a newly characterized effect in which solute atoms are `buffeted' by the peripheral atoms of adjacent solvent molecules. The present work concerns more detailed studies of the buffeting screening, which is governed by sterically controlled parameter (2T - T)2, where and are geometric structural parameters. The original approach is used to characterise the buffeting shifts induced by large solvent molecules and the approach is found to be inadequate. Consequently, improved methods of calculating and are reported. Using the improved approach it is shown that buffeting is dependent on the nature of the solvent as well as the nature of the solute molecule. Detailed investigation of the buffeting component of the van der Waals chemical shifts of selected solutes in a range of solvents containing either H or Cl as peripheral atoms have enabled the determination of a theoretical acceptable value for the classical screening coefficient B for protons. 1H and 13C resonance studies of tetraethylmethane and 1H, 13C and 29Si resonance studies of TMS have been used to support the original contention that three (< R1; 2> , < R2; 2> and E2BI) components of intermolecular van der Waals dispersion fields are required to characterise vdW chemical shifts.

The separation of secondary oil-water dispersions in particulate beds

The literature relating to haze formation, methods of separation, coalescence mechanisms, and models by which droplets <100 μm are collected, coalesced and transferred, have been reviewed with particular reference to particulate bed coalescers. The separation of secondary oil-water dispersions was studied experimentally using packed beds of monosized glass ballotini particles. The variables investigated were superficial velocity, bed depth, particle size, and the phase ratio and drop size distribution of inlet secondary dispersion. A modified pump loop was used to generate secondary dispersions of toluene or Clairsol 350 in water with phase ratios between 0.5-6.0 v/v%.Inlet drop size distributions were determined using a Malvern Particle Size Analyser;effluent, coalesced droplets were sized by photography. Single phase flow pressure drop data were correlated by means of a Carman-Kozeny type equation. Correlations were obtained relating single and two phase pressure drops, as (ΔP2/μc)/ΔP1/μd) = kp Ua Lb dcc dpd Cine A flow equation was derived to correlate the two phase pressure drop data as, ΔP2/(ρcU2) = 8.64*107 [dc/D]-0.27 [L/D]0.71 [dp/D]-0.17 [NRe]1.5 [e1]-0.14 [Cin]0.26  In a comparison between functions to characterise the inlet drop size distributions a modification of the Weibull function provided the best fit of experimental data. The general mean drop diameter was correlated by: q_p q_p p_q /β      Γ ((q-3/β) +1) d qp = d fr  .α        Γ ((P-3/β +1 The measured and predicted mean inlet drop diameters agreed within ±15%. Secondary dispersion separation depends largely upon drop capture within a bed. A theoretical analysis of drop capture mechanisms in this work indicated that indirect interception and London-van der Waal's mechanisms predominate. Mathematical models of dispersed phase concentration m the bed were developed by considering drop motion to be analogous to molecular diffusion.The number of possible channels in a bed was predicted from a model in which the pores comprised randomly-interconnected passage-ways between adjacent packing elements and axial flow occured in cylinders on an equilateral triangular pitch. An expression was derived for length of service channels in a queuing system leading to the prediction of filter coefficients. The insight provided into the mechanisms of drop collection and travel, and the correlations of operating parameters, should assist design of industrial particulate bed coalescers.

Molecular architecture influences on material properties of pharmaceutical compounds

Salt formation has extensively been studied as a strategy to improve drug solubility but it has not been explored as a strategy to improve mechanical properties. A better understanding of which factors of the solid state can have an influence in the mechanical properties of pharmaceutical powders can help to optimise and reduce cost of tablet manufacturing. The aim of this study was to form different series of amine salts of flurbiprofen, gemfibrozil and diclofenac and to establish predictive relationships between architectural characteristics and physicochemical and mechanical properties of the salts. For this purpose, three different carboxylic acid drugs were selected: flurbiprofen, gemfibrozil and diclofenac, similar in size but varying in flexibility and shape and three different series of counterions were also chosen: one with increasing bulk and no hydroxyl groups to limit the hydrogen bonding potential; a second one with increasing number of hydroxyl groups and finally a third series, related to the latter in number of hydroxyl groups but with different molecular shape and flexibility. Physico-chemical characterization was performed (DSC, TGA, solubility, intrinsic dissolution rate, particle size, true density) and mechanical properties measured using a compaction replicator. Strained molecular conformations produce weaker compacts as they have higher energy than preferred conformations that usually lie close to energy minimums and oppose plastic deformation. It was observed that slip planes, which correspond to regions of weakest interaction between the planes, were associated with improved plasticity and stronger compacts. Apart from hydrogen bonds, profuse van der Waals forces can result in ineffective slip planes. Salts displaying two-dimensional densely hydrogen bonded layers produced stronger compacts than salts showing one-dimensional networks of non-bonded columns, probably by reducing the attachment energy between layers. When hydrogen bonds are created intramolecularly, it is possible that the mechanical properties are compromised as they do not contribute so much to create twodimensional densely bonded layers and they can force molecules into strained conformations. Some types of hydrogen bonding network may be associated with improved mechanical properties, such as type II, or R (10) 3 4 using graph-set notation, versus type III, or R (12) 4 8 , columns. This work clearly demonstrates the potential of investigating crystal structure-mechanical property relationship in pharmaceutical materials.

Viscoelasticity and high buckling stress of dense carbon nanotube brushes

We report on the mechanical behavior of a dense brush of small-diameter (1–3 nm) non-catalytic multiwall (2–4 walls) carbon nanotubes (CNTs), with ~10 times higher density than CNT brushes produced by other methods. Under compression with spherical indenters of different radii, these highly dense CNT brushes exhibit a higher modulus (~17–20 GPa) and orders of magnitude higher resistance to buckling than vapor phase deposited CNT brushes or carbon walls. We also demonstrate the viscoelastic behavior, caused by the increased influence of the van der Waals’ forces in these highly dense CNT brushes, showing their promise for energy-absorbing coatings.

Supervisor-subordinate age dissimilarity and performance ratings:the buffering effects of supervisory relationship practice

Using 394 pairs of employees and their immediate supervisors working in the Information and Communication Technology (ICT) sector in three northern European countries, this study examined the effect of workplace moderators on the link between relational demography and supervisor ratings of performance. Directional age differences between superior and subordinate (i.e., status incongruence caused when the supervisor is older or younger than his/her subordinate) and non-directional age differences were used as predictors of supervisor ratings of occupational expertise. The quality of the supervisor-subordinate relationship and the existence of positive age-related supervisory practices were examined as moderators of this relationship. The results provide no support for a relationship between directional age differences and age-related stereotyping by supervisors in ratings of performance, neither for the effects of age-related supervisory practices. However, high quality supervisor-subordinate relationships did moderate the effects of age dissimilarity on supervisory ratings. The implications of these findings for performance appraisal methodologies and recommendations for further research are discussed.

Genetic analysis of dyslexia candidate genes in the European cross-linguistic NeuroDys cohort

Dyslexia is one of the most common childhood disorders with a prevalence of around 5-10% in school-age children. Although an important genetic component is known to have a role in the aetiology of dyslexia, we are far from understanding the molecular mechanisms leading to the disorder. Several candidate genes have been implicated in dyslexia, including DYX1C1, DCDC2, KIAA0319, and the MRPL19/C2ORF3 locus, each with reports of both positive and no replications. We generated a European cross-linguistic sample of school-age children-the NeuroDys cohort-that includes more than 900 individuals with dyslexia, sampled with homogenous inclusion criteria across eight European countries, and a comparable number of controls. Here, we describe association analysis of the dyslexia candidate genes/locus in the NeuroDys cohort. We performed both case-control and quantitative association analyses of single markers and haplotypes previously reported to be dyslexia-associated. Although we observed association signals in samples from single countries, we did not find any marker or haplotype that was significantly associated with either case-control status or quantitative measurements of word-reading or spelling in the meta-analysis of all eight countries combined. Like in other neurocognitive disorders, our findings underline the need for larger sample sizes to validate possibly weak genetic effects. © 2014 Macmillan Publishers Limited All rights reserved.

Editorial

Readers may have noted that a short but very important announcement was made in the last issue of CLAE, at the top of the contents page. CLAE has been accepted by Thomson Reuters for abstracting and indexing in its SciSearch, Journal Citation Reports, and Current Contents services. This will ensure a greater visibility to the international research community. In addition, in June 2012 CLAE will receive its very first official Impact Factor – a measure of journal influence of importance to authors and readers alike. The impact factor value has not yet been decided but internal estimates by Elsevier estimate it will be around 1, and it will be applied to all CLAE issue back to January 2009 (volume 32). I would guess readers at this stage would have one of two responses – either ‘that's good news’ or perhaps ‘what's an impact factor?’ If you are in the latter camp then allow me to try and explain. Basically the impact factor or citation index of a journal is based on how many times in the previous year papers published in that journal in the previous two years were cited by authors publishing in other journals. So the 2012 impact factor for CLAE is calculated on how many times in 2011 papers that were published in CLAE in 2010 and 2009 were cited in other journals in 2011, divided by the number of papers published in CLAE 2010 and 2009. Essentially authors will try and get their work published in journals with a higher impact factor as it is thought that the paper will be cited more by other authors or the paper will have higher visibility in the arena. For universities having its published output in higher journals is one of the markers used to judge esteem. For individual authors publishing in journals with a higher impact factor or the number of times one of their papers is published is something that they are likely to add to their CVs or demonstrate the importance of their work. Journals with higher impact factors tend to be more review journals or journals with a wider spectrum so for a relatively small journal with a specialised field like CLAE it is great to be listed with a citation index. The awarding of a citation index crowns many changes that CLAE has undergone since the current Editor took the reins in 2005. CLAE has increased from four issues (in 2004) to six issues per year with at least one review article per issue and one article with continuing education per issue. The rejection rate has gone up significantly meaning that only best papers are published (currently it stands at 37%). CLAE has been Medline/Pubmed indexed for a few years now which is also a very important factor in improving visibility of the journal. The submission and reviewing process for CLAE in now entirely online and finally the editorial board has changed from being merely a list of keynote people to being an active group of keynote people who are enthusiastically involved with the journal. From the editorial board one person is appointed as a Reviews Editor plus we have two additional editors who work as Regional Editors. As ever, on behalf of CLAE I would like to thank the BCLA Council for their continued support (especially Vivien Freeman) and Elsevier for their continuing guidance (in particular Andrew Miller and Rosie Davey) and the excellent Editorial Board (Christopher Snyder, Pauline Cho, Eric Papas, Jan Bergmanson, Roger Buckley, Patrick Caroline, Dwight Cavanagh, Robin Chalmers, Michael Doughty, Nathan Efron, Michel Guillon, Nizar Hirji, Meng Lin, Florence Malet, Philip Morgan, Deborah Sweeney, Brian Tighe, Eef van Der Worp, Barry Weissman, Mark Willcox, James Wolffsohn and Craig Woods). And finally, a big thanks to the authors and reviewers who work tirelessly putting manuscripts together for publication in CLAE. Copyright © 2012 Published by Elsevier Ltd.

Resource-efficient supply chains:a research framework, literature review and research agenda

Purpose: To define a research agenda for creating Resource-Efficient Supply Chains (RESC) by identifying and analysing their key characteristics as well as future research opportunities. Design/methodology/approach: We follow a systematic review method to analyse the literature and to understand RESC taking a substantive theory approach. Our approach is grounded in a specific domain, the agri-food sector, because it is an intensive user of an extensive range of resources. Findings: The review shows that literature has looked at the use of resources primarily from the environmental impact perspective. It shows a lack of understanding of the specific RESC characteristics, and concludes more research is needed on multi-disciplinary methods for resource use and impact analyses as well as assessment methods for resource sensitivity and responsiveness. There is a need to explore whether or not, and how, logistics/supply chain decisions will affect the overall configuration of future food supply chains in an era of resource scarcity and depletion and what the trade-offs will be. Research limitations/implications: The paper proposes an agenda for future research in the area of resource–efficient supply chain. The framework proposed along with the key characteristics identified for RESC can be applied to other sectors. Practical implications: Our research should facilitate further understanding of the implications and trade-offs of supply chain decisions taken on the use of resources by supply chain managers. Originality/value: The paper explores the interaction between supply chains and natural resources and also defines the key characteristics of RESC.

International session at the BCLA conference

Full text: It seems a long time ago now since we were at the BCLA conference. The excellent FIFA World Cup in Brazil kept us occupied over the summer as well as Formula 1, Wimbledon, Tour de France, Commonwealth Games and of course exam paper marking! The BCLA conference this year was held in Birmingham at the International Convention Centre which again proved to be a great venue. The number of attendees overall was up on previous years, and at a record high of 1500 people. Amongst the highlights at this year's annual conference was the live surgery link where Professor Sunil Shah demonstrated the differences in technique between traditional phacoemulsification cataract surgery and femtosecond assisted phacoemulsification cataract surgery. Dr. Raquel Gil Cazorla, a research optometrist at Aston University, assisted in the procedure including calibrating the femtosecond laser. Another highlight for me was the session that I chaired, which was the international session organised by IACLE (International Association of CL Educators). There was a talk by Mirjam van Tilborg about dry eye prevalence in the Netherlands and how it was managed by medical general practitioners (GPs) or optometrists. It was interesting to know that there are only 2 schools of optometry there and currently under 1000 registered optometrists there. It also seems that GPs were more likely to blame CL as the cause for dry eye whereas optometrists who had a fuller range of tests were better at solving the issue. The next part of the session included the presentation of 5 selected posters from around the world. The posters were also displayed in the main poster area but were selected to be presented here as they had international relevance. The posters were: 1. Motivators and Barriers for Contact Lens Recommendation and Wear by Nilesh Thite (India) 2. Contact lens hygiene among Saudi wearers by Dr. Ali Masmaly (Saudi) 3. Trends of contact lens prescribing and patterns of contact lens practice in Jordan by Dr. Mera Haddad (Jordan) 4. Contact Lens Behaviour in Greece by Dr. Dimitra Makrynioti (Greece) 5. How practitioners inform ametropes about the benefits of contact lenses and overcome the potential barriers: an Italian survey, by Dr. Fabrizio Zeri (Italy) It was interesting to learn about CL practice in different parts, for example the CL wearing population ration in Saudi Arabia is around 1:2 Male:Female (similar to other parts of the world) and although the sale of CL is restricted to registered practitioners there are many unregistered outlets, like clothing stores, that flout the rules. In Jordan some older practitioners will still advise patients to use tap water or even saliva! But thankfully the newer generation of practitioners have been educated not to advise this. In Greece one of the concerns was that some practitioners may advise patients to use disposable lenses for longer than they should and again it seems to be the practitioners with inadequate education that would do this. In India it was found that cost was one barrier to using contact lenses but also some practitioners felt that they shouldn’t offer CLs due to cost too. In Italy sensitive eyes and CL care and maintenance were the barriers to CL wear but the motivators were vision and comfort and aesthetics. Finally the international session ended with the IACLE travel award and educator awards presented by IACLE president Shehzad Naroo and BCLA President Andrew Yorke. The travel award went to Wang Ling, Jinling Institute of Technology, Nanjing, China. There were 3 regional Contact Lens Educator of the Year Awards sponsored by Coopervision and presented by Dr. J.C. Aragorn of Coopervision. 1. Asia Pacific Region – Dr. Rajeswari Mahadevan of Sankara Nethralaya Medical Research Foundation, Chennai, India 2. Americas Region – Dr. Sergio Garcia of University of La Salle, Bogotá and the University Santo Tomás, Bucaramanga, Colombia 3. Europe/Africa – Middle East Region: Dr. Eef van der Worp, affiliated with the University of Maastricht, the Netherlands The posters above were just a small selection of those displayed at this year's BCLA conference. If you missed the BCLA conference then you can see the abstracts for all posters and talks in a virtual issue of CLAE very soon. The poster competition was kindly sponsored by Elsevier. The poster winner this year was: Joan Gispets – Corneal and Anterior Chamber Parameters in Keratoconus The 3 runners up were: Debby Yeung – Scleral Lens Central Corneal Clearance Assessment with Biomicroscopy Sarah L. Smith – Subjective Grading of Lid Margin Staining Heiko Pult – Impact of Soft Contact Lenses on Lid Parallel Conjunctival Folds My final two highlights are a little more personal. Firstly, I was awarded Honorary Life Fellowship of the BCLA for my work with the Journal, and I would like to thank the BCLA, Elsevier, the editorial board of CLAE, the reviewers and the authors for their support of my role. My final highlight from the BCLA conference this year was the final presentation of the conference – the BCLA Gold Medal award. The recipient this year was Professor Philip Morgan with his talk ‘Changing the world with contact lenses’. Phil was the person who advised me to go to my first BCLA conference in 1994 (funnily he didn’t attend himself as he was busy getting married!) and now 20 years later he was being honoured with the accolade of being the BCLA Gold Medallist. The date of his BCLA medal addressed was shared with his father's birthday so a double celebration for Phil. Well done to outgoing BCLA President Andy Yorke and his team at the BCLA (including Nick Rumney, Cheryl Donnelly, Sarah Greenwood and Amir Khan) on an excellent conference. And finally welcome to new President Susan Bowers. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Methyl chloride purification for the silicone industry

This study experimentally investigated methyl chloride (MeCl) purification method using an inhouse designed and built volumetric adsorption/desorption rig. MeCl is an essential raw material in the manufacture of silicone however all technical grades of MeCl contain concentrations (0.2 - 1.0 % wt) of dimethyl ether (DME) which poison the process. The project industrial partner had previously exhausted numerous separation methods, which all have been deemed not suitable for various reasons. Therefore, adsorption/desorption separation was proposed in this study as a potential solution with less economic and environmental impact. Pure component adsorption/desorption was carried out for DME and MeCl on six different adsorbents namely: zeolite molecular sieves (types 4 Å and 5 Å); silica gels (35-70 mesh, amorphous precipitated, and 35-60 mesh) and granular activated carbon (type 8-12 mesh). Subsequent binary gas mixture adsorption in batch and continuous mode was carried out on both zeolites and all three silica gels following thermal pre-treatment in vacuum. The adsorbents were tested as received and after being subjected to different thermal and vacuum pre-treatment conditions. The various adsorption studies were carried out at low pressure and temperature ranges of 0.5 - 3.5 atm and 20 - 100 °C. All adsorbents were characterised using Brunauer Emmett Teller (BET), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) to investigate their physical and chemical properties. The well-known helium (He) expansion method was used to determine the empty manifold and adsorption cell (AC) regions and respective void volumes for the different adsorbents. The amounts adsorbed were determined using Ideal gas laws via the differential pressure method. The heat of adsorption for the various adsorbate-adsorbent (A-S) interactions was calculated using a new calorimetric method based on direct temperature measurements inside the AC. Further adsorption analysis included use of various empirical and kinetic models to determine and understand the behaviour of the respective interactions. The gas purification behaviour was investigated using gas chromatography and mass spectroscopy (GC-MC) analysis. Binary gas mixture samples were syringed from the manifold iii and AC outlet before and after adsorption/desorption analysis through manual sample injections into the GC-MS to detect and quantify the presence of DME and ultimately observe for methyl chloride purification. Convincing gas purification behaviour was confirmed using two different GC columns, thus giving more confidence on the measurement reliability. From the single pure component adsorption of DME and MeCl on the as received zeolite 4A subjected to 1 h vacuum pre-treatment, both gases exhibited pseudo second order adsorption kinetics with DME exhibiting a rate constant nearly double that of MeCl thus suggesting a faster rate of adsorption. From the adsorption isotherm classification both DME and MeCl exhibited Type II and I adsorption isotherm classifications, respectively. The strength of bonding was confirmed by the differential heat of adsorption measurement, which was found to be 23.30 and 10.21 kJ mol-1 for DME and MeCl, respectively. The former is believed to adsorb heterogeneously through hydrogen bonding whilst MeCl adsorbs homogenously via van der Waal’s (VDW) forces. Single pure component adsorption on as received zeolite 5A, silica gels (35-70, amorphous precipitated and 35-60) resulted in similar adsorption/desorption behaviour in similar quantities (mol kg-1). The adsorption isotherms for DME and MeCl on zeolite 5A, silica gels (35-70, amorphous precipitated and 35-60) and activated carbon 8-12 exhibited Type I classifications, respectively. Experiments on zeolite 5A indicated that DME adsorbed stronger, faster and with a slightly stronger strength of interaction than MeCl but in lesser quantities. On the silica gels adsorbents, DME exhibited a slightly greater adsorption capacity whilst adsorbing at a similar rate and strength of interaction compared to MeCl. On the activated carbon adsorbent, MeCl exhibited the greater adsorption capacity at a faster rate but with similar heats of adsorption. The effect of prolonged vacuum (15 h), thermal pre-treatment (150 °C) and extended equilibrium time (15 min) were investigated for the adsorption behaviour of DME and MeCl on both zeolites 4A and 5A, respectively. Compared to adsorption on as received adsorbents subjected to 1 h vacuum the adsorption capacities for DME and MeCl were found to increase by 1.95 % and 20.37 % on zeolite 4A and by 4.52 % and 6.69 % on zeolite 5A, respectively. In addition the empirical and kinetic models and differential heats of adsorption resulted in more definitive fitting curves and trends due to the true equilibrium position of the adsorbate with the adsorbent. Batch binary mixture adsorption on thermally and vacuum pre-treated zeolite 4A demonstrated purification behaviour of all adsorbents used for MeCl streams containing DME impurities, with a concentration as low as 0.66 vol. %. The GC-MS analysis showed no DME detection for the tested concentration mixtures at the AC outlet after 15 or 30 min, whereas MeCl was detectable in measurable amounts. Similar behaviour was also observed when carrying out adsorption in continuous mode. On the other hand, similar studies on the other adsorbents did not show such favourable MeCl purification behaviour. Overall this study investigated a wide range of adsorbents (zeolites, silica gels and activated carbon) and demonstrated for the first time potential to purify MeCl streams containing DME impurities using adsorption/desorption separation under different adsorbent pre-treatment and adsorption operating conditions. The study also revealed for the first time the adsorption isotherms, empirical and kinetic models and heats of adsorption for the respective adsorbentsurface (A-S) interactions. In conclusion, this study has shown strong evidence to propose zeolite 4A for adsorptive purification of MeCl. It is believed that with a technical grade MeCl stream competitive yet simultaneous co-adsorption of DME and MeCl occurs with evidence of molecular sieiving effects whereby the larger DME molecules are unable to penetrate through the adsorbent bed whereas the smaller MeCl molecules diffuse through resulting in a purified MeCl stream at the AC outlet. Ultimately, further studies are recommended for increased adsorption capacities by considering wider operating conditions, e.g. different adsorbent thermal and vacuum pre-treatment and adsorbing at temperatures closer to the boiling point of the gases and different conditions of pressure and temperature.