Hydrodynamics and mixer-induced bubble formation in micro bubble columns with single and multiple-channels

A hydrodynamic characterization of an industrially used gas-liquid contacting microchannel. device is discussed, viz. the micro bubble column of IMM. Furthermore, similar characterization of a gas-liquid flow microchip of TU/e, with two tailored mixer designs, is used to solve fundamental issues on hydrodynamics, and therefore, to achieve further design and operating optimization of that chip and the IMM device. Flow pattern maps are presented in a dimensionless fashion for further predictions on new fluidic systems for optimum single-channel multiphase operation. Bubble formation was investigated in the two types of mixers and pinch-off and hydrodynamic decay mechanisms are observed. The impact of these mechanisms on bubble size, bubble size distributions, and on the corresponding flow patterns, i.e., the type of mixer design, can be decisive for the flow pattern map and thus, may be used to alter flow pattern maps. The bubble sizes and their distribution were improved for the tailored designs, i.e., smaller and more regular bubbles were generated. Finally, the impact of multi-channel distribution for gas and liquid flow is demonstrated. Intermediate flow patterns such as slug-annular flow, also found for single-phase operation, and the simultaneous coexistence of flow regimes are presented, with the latter providing evidence of flow maldistribution.

Hydrothermal synthesis and characterization of ZSM-5 coatings on a molybdenum support and scale-up for application in micro reactors

A procedure has been developed to grow ZSM-5 crystals in situ on a molybdenum (Mo) support. The high heat conductivity (138 W/mK) and high mechanical stability at elevated temperatures of the Mo support allow the application of ZSM-5 coatings in micro reactors for high temperature processes involving large heat effects. The effect of the synthesis mixture composition on ZSM-5 coverage and on the uniformity of the ZSNI-5 coatings was investigated on plates of 10 X 10 mm(2). Ratios of H2O/Si = 50, SUAI = 25, and TPA/Al = 2.0 were found to be optimal for the formation of uniform coatings of 6 g/m(2) at a temperature of 150 degrees C and a synthesis time of 48 h. Scaling up of the synthesis procedure on 72 Mo plates of 40 x 9.8 x 0.1 mm 3 resulted in a uniform coverage of 14.8 +/- 0.4 g/m(2). The low deviation per individual plate (

An in vitro Study to Assess the Potential of a Unique Micro porous Algal Derived Cap Bone Void Filler in Comparison with Clinically-Used Bone Void Fillers

Macroporosity(>100µm) in bone void fillers is a known prerequisite for tissue regeneration, but recent literature has highlighted the added benefit of microporosity(0.5 - 10µm). The aim of this study was to compare the in vitro performances of a novel interconnective microporous hydroxyapatite (HA) derived from red algae to four clinically available macroporous calcium phosphate (CaP) bone void fillers. The use of algae as a starting material for this novel void filler overcomes the issue of sustainability, which overshadows continued use of scleractinian coral in the production of some commercially available materials, namely Pro-OsteonTM and Bio-Coral®. This study investigated the physicochemical properties of each bone voidfiller material using x-ray diffraction, fourier transform infrared spectroscopy, inductive coupled plasma, and nitrogen gas absorption and mercury porosimetry. Biochemical analysis, XTT, picogreen and alkaline phosphatase assays were used to evaluate the biological performances of the five materials. Results showed that algal HA is non-toxic to human foetal osteoblast (hFOB) cells and supports cell proliferation and differentiation. The preliminary in vitro testing of microporous algal-HA suggests that it is comparable to the four clinically approved macroporous bone void fillers tested. The results demonstrate that microporous algal HA has good potential for use in vivo and in new tissue engineered strategies for hard tissue repair.

An Examination of Volunteer Motivation in Credit Unions: Informing Volunteer Resource Management

Volunteer recruitment and retention is a problem that most credit unions experience. Research suggests that knowledge of volunteer motivation can inform volunteer management strategies. This paper uses a survey approach to determine whether current volunteers in credit unions in Northern Ireland are more motivated by the actual act of volunteering, by the output from the volunteering activity (including altruism) or because the volunteering activity increases their human capital value. Altruistic reasons are found to be the most influential, with the act of volunteering also scoring highly. This knowledge should inform volunteer recruitment programmes and internal appraisal processes as management can reinforce messages that provide positive feedback to volunteers on the social benefits being achieved by the credit union. This will further motivate current volunteers, ensuring retention. When motivation was analyzed by volunteer characteristics we found that older volunteers, retired volunteers and volunteers who are less educated are more motivated in their role. There was little evidence that individuals volunteer to improve their human capital worth.

Profiling: a Strategy for Successful Volunteer Recruitment in Credit Unions

Credit unions are non-profit financial organisations that provide financial services to their members. They are located in 97 countries across the world. All credit unions are governed by a volunteer board and many are reliant on volunteers for all their labour requirements. However, recruiting volunteers is a problem. The literature on recruitment issues in volunteering in general, suggests that the not-for-profit sector looks to the private sector for guidance on recruitment policies and approaches. One such approach which is considered in this paper is ‘market segmentation’ wherein the potential volunteer body is profiled to determine if an individual is likely to volunteer and if they are, to identify the type of role they are most likely to be attracted to. Prior literature on volunteering in non-profit organisations suggests that certain types of individual (dominant individuals) are more likely to volunteer. This paper investigates whether this dominant status profile is evident amongst volunteers in credit unions in Northern Ireland (NI). The study finds that people with dominant characteristics are more likely to be attracted to volunteering to the board of directors and individuals who have less dominant traits overall should be offered more social/participative type roles. This information can be used by credit union governing boards for volunteer recruitment, retention and management purposes.

“An Examination of the Key Factor of Influence In the Development Process of Credit Union Industries,”

The aim of this paper is to analyse credit union industries within a development framework. Explicit consideration is given to credit union industries in four countries – Great Britain, Ireland, New Zealand and the United States. It is argued that in terms of a developmental typology the credit union industry in Great Britain is at a nascent stage of development, the industries in Ireland and New Zealand are at a transition stage while the US credit union industry is mature in nature. In progression between stages the analysis considers the influence of factors such as situational leadership, the complexion of trade associations, professionalisation, regulatory and legislative initiatives and technology. The analysis concluded that while there was a substantial commonality of experience, there were also significant differences in the impact of these factors. This consequently encouraged the recognition of the existence of ‘a variety of the species’ in respect of credit union development.

A charged-particle microbeam .2. A single-particle micro-collimation and detection system.

The use of a charged-particle microbeam provides a unique opportunity to control precisely, the number of particles traversing individual cells and the localization of dose within the cell. The accuracy of 'aiming' and of delivering a precise number of particles crucially depends on the design and implementation of the collimation and detection system. This report describes the methods available for collimating and detecting energetic particles in the context of a radiobiological microbeam. The arrangement developed at the Gray Laboratory uses either a 'V'-groove or a thick-walled glass capillary to achieve 2-5 mu m spatial resolution. The particle detection system uses an 18 mu m thick transmission scintillator and photomultiplier tube to detect particles with >99% efficiency.