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Mechanical properties of nickel-graphene composites synthesized by electrochemical deposition
No full textGraphene (Gr) nanosheets with multilayer structures were dispersed in a nickel (Ni) plating solution by using a surfactant with a magnetic stirring method. Gr nanosheets were incorporated into a Ni matrix through a plating process to form Ni-Gr composites on a target substrate. Gr nanosheets were uniformly dispersed in the Ni matrix, and the oxygen radicals present in the Gr were reduced during the electro-deposition process. The incorporation of Gr in the Ni matrix increases both the inter-planar spacing and the degree of preferred orientation of crystalline Ni. With the addition of Gr content as low as 0.05 g L−1, the elastic modulus and hardness of the Ni-Gr composites reach 240 GPa and 4.6 GPa, respectively, which are about 1.7 and 1.2 times that of the pure Ni deposited under the same condition. The enhancement in mechanical properties of the composites is attributed to the preferred formation of the Ni crystalline phases in its (111) plane, the high interaction between Ni and Gr and the prevention of the dislocation sliding in the Ni matrix by the Gr. The results suggest that the method of using Gr directly instead of graphene oxide (GO) is efficient and scalable
Low-pressure H₂, NH₃ microwave plasma treatment of Polytetrafluoroethylene (PTFE) powders: chemical, thermal and wettability analysis.
No full textFunctionalization of Polytetrafluoroethylene (PTFE) powders of ~6 μm particle size is carried out using low-pressure 2.45 GHz H₂, NH₃ microwave plasmas for various durations (2.5, 10 h) to chemically modify their surface and alter their surface energy.The X-ray Photoelectron Spectroscopy (XPS) analyses reveal that plasma treatment leads to significant defluorination (F/C atomic ratio of 1.13 and 1.30 for 10 h NH₃ and H₂ plasma treatments, respectively vs. 1.86 for pristine PTFE), along with the incorporation of functional polar moieties on the surface, resulting in enhanced wettability. Analysis of temperature dependent XPS revealed a loss of surface moieties above 200 °C, however, the functional groups are not completely removable even at higher temperatures (>300 °C), thus enabling the use of plasma treated PTFE powders as potential tribological fillers in high temperature engineering polymers. Ageing studies carried over a period of 12 months revealed that while the surface changes degenerate over time, again, they are not completely reversible. These functionalised PTFE powders can be further used for applications into smart, high performance materials such as tribological fillers for engineering polymers and bio-medical, bio-material applications
Controlled synthesis of TiO2 using a combined sol gel and dielectrophoresis method
No full textA controlled synthesis of titanium dioxide nanoparticles (TiO2-NPs) with uniform size and a specific crystal structure could be achieved by a combined sol gel/dielectrophoresis (DEP) approach. The applied voltage could influence the crystal structure and particle size
Assessing victim risk in cases of violent crime
No full textPurpose
– There is a body of evidence that suggests a range of psychosocial characteristics demarcate certain adults to be at an elevated risk for victimisation. The purpose of this paper is to examine consistency between one police force, and a corresponding Victim Support service based in England, in their assessment of level of risk faced by victims of violent crime.
Design/methodology/approach
– This study explored matched data on 869 adult victims of violent crime gathered from these two key services in Preston, namely, Lancashire Constabulary and Victim Support, from which a sub-group of comparable “domestic violence” cases (n=211) were selected for further examination.
Findings
– Data analyses revealed methodological inconsistencies in the assessment of victimisation resulting in discrepancies for recorded levels of risk in domestic violence cases across these two agencies.
Practical implications
– These findings provide a compelling argument for developing a more uniformed approach to victim assessment and indicate a significant training need.
Originality/value
– This paper highlights areas of good practice and forwards several recommendations for improved practice that emphasises the integration of empirical research conducted by psychologists to boost the validity and reliability of risk assessment approaches and tools used
Knowledge management on site: a case study project
No full textConstruction is a knowledge-intensive industry. However, the majority of knowledge management research focuses on corporate and managerial levels rather than on constructions sites. Sites are where money is made or lost, and decisions made which impact expenditure, efficiency and productivity. To support this macro-or organisational-level research, this paper aims to develop insight at the micro or site level, to help inform knowledge management decisions made at corporate level. It reports the findings of a case study that examined knowledge management in operation on a small civil engineering project in north-west England. Data, including participant observation, unstructured interviews and project documentation, were analysed to explore the creation, flow and transfer of knowledge throughout the project. Complex relationships existed between explicit and tacit knowledge, while predicted and unpredicted knowledge gains could also be identified alongside 'aspirational' knowledge. A reliance on 'pending' knowledge to make decisions that influence project performance suggests improved knowledge management within a more integrated project team would be beneficial. Knowledge management was found to be limited by the tacit nature of much of the knowledge generated on the project, and the lack of formal feedback into an organisational knowledge management system
The Higher Education Classification of Subjects (HECoS) vocabulary. HEDIIP project public deliverable 4.
No full textA report on the development of the Higher Education Classification of Subjects vocabulary, with an account of feedback on it by stakeholders, and how the feedback has been used.The New Subject Coding Scheme project was commissioned by HEDIIP under the Standards and Understanding theme. The project aims to develop a replacement for the Joint Academic Coding System that meets the needs of a broad group of stakeholders and reflected the diverse and dynamic nature of Higher Education in the twenty-first century. The New Subject Coding Scheme Project is undertaken by the Centre for Educational Technology, Interoperability and Standards (CETIS) with partners Aspire Ltd and APS Ltd. in two phases between July 2014 and October 2015. The project undertook extensive stakeholder engagement to identify the requirements for the new coding system and developed a coding structure that aims to meet these requirements. The new coding scheme is referred to as HECoS – the Higher Education Classification of Subjects
Tutors’ Perceptions on the Pedagogical Validity of Teaching ‘Taboo’ Topics in the Second Language Learning Sector
No full textThe purpose of this study is to establish teachers’ perceptions of the pedagogical value of introducing taboo or controversial topics into an L2 classroom. In order to achieve the aims of this study a semi-structured interview was designed and conducted with five experienced ESOL tutors. A focus group of trainee tutors were also interviewed for purposes of comparison and triangulation. Overall, participants agreed that the introduction of taboo/controversial topics did have some pedagogical relevance. Specifically from a language learning point of view taboo/controversial topics were seen to be technique that could prompt previously unknown vocabulary and linguistic structures. Others recognised the potential for such issues as a method to widen the learners understanding of the attitudes and values the target culture has.In conclusion, the personal perceptions of the tutors indicate that many understood that there was an efficacy to using taboo/controversial issues as a learning tool, ranging from basic language skills to promoting cultural enrichment, and potentially promoting a higher level of societal engagement. Yet, the primary concern of maintaining the welfare of the learners was the dominating factor as to whether tutors would introduce taboo/controversial issues into the class. Lastly, there are indications that the influence of L2 tutors on possible changes to the current method of avoidance of taboo/controversial topics is much greater than realised
Novel Metal Complex Fire Retardants for Engineering Polymers.
No full textThe aims of this project were to develop non-halogenated, non-toxic and environmentally benign synthetic inorganic compounds capable of imparting flame retardant and/or synergistic activity with selected conventional flame retardants to selected engineering polymer systems.Following a comprehensive literature survey with specific focus centered upon the degradation and fire retardancy of polyamide 6,6 (PA66), an initial study of the effect of several metal oxalates on the burn rate of impregnated cotton in combination with sources of bromine and phosphorus was performed, with some promising synergistic activity detected with the former.Following this, a matrix of potential non-toxic inorganic flame retardant candidates (FRCs) was devised from a range of non-toxic, water-soluble precursors. And 180 FRCs were successfully synthesised and a cursory characterisation was conducted using X-Ray Fluorescence (XRF). These were screened for potential flame retardant properties with polyamide 6,6 (PA66) as a suitable engineering polymer. PA66 pellets were powdered and mixed with each FRC in 3:1 mass ratio, and subjected to simultaneous differential thermal analysis/thermogravimetric analysis (TGA/DTA), to which a range of selection parameters were applied, assessing their stability and char-forming potential. All FRCs which did not conform to these conditions were eliminated, reducing the number to 60. Differential mass analysis was performed on TGAs of the 60 FRCs to better define their char promotion potential in PA66, thereby narrowing these down to 16 samples: aluminium, zinc and tin (II) tungstates (AlW, ZnW and SnW respectively); zinc molybdate (ZnMo); iron aluminate (FeAl); iron (III) hypophosphite (FeHP); zinc oxalate (ZnOx); three stannic metal nitrite complexes (SnMNO where M = Mn, Cu or Zn), tin (II) oxide (SnO), hydrogenphosphite (SnH2PO3), triphosphate (SnTP) and phenylphosphonate (SnPhPO3); and tin (IV) silicate (SnSi).The 16 selected were synthesised on a larger scale and fully characterised, of which 6 were discounted due to difficulties in synthesis scaling, or characterisation. The final 10 FRCs were selected for small-scale fire testing in PA66 (at 5 wt%), using UL94, LOI and cone calorimetry with additional analysis provided by TGA/DTA. All samples were prepared by melt compounding, during which two of the samples (ZnMo and FeHP) displayed erroneous activity during processing and so were eliminated.The remaining 8 FRCs had little effect on PA66 LOI performance with only two samples (AlW and SnW) marginally improving UL94 performance. All samples reduced cone peak heat release rate (PHRR) to levels ranging from 70 % (ZnW) to 53 % (FeAl) compared to the PA66 control. Two FRCs (SnPhPO3 and SnH2PO3) incorporated at a higher level (10 wt%) showed improved performance iv although insufficient for achieving acceptable levels of flame retardancy. Further studies were undertaken to test potential synergism of the FRCs with several phosphorus- and bromine containing flame retardants.Combinations of 3 phosphorus-containing flame retardants (PFRs) with each of the 4 FRCs, FeAl, AlW, SnW and ZnW were studied. A degree of synergy with AlW and SnW combined with aluminium phosphinate (AlPi) was observed and for SnW with a combination of AlPi with melamine polyphosphate (MPP) with respect to UL94 and LOI performance. A moderate reduction in cone PHRR was observed for all FRCs combined with AlPi, and a significant reduction for all with AlPi/MPP. AlW, SnW and ZnW combined with MPP showed moderate improvements in UL94 and LOI and slight reductions in PHRR relative to the MPP control. These results indicate a degree of synergism of several FRCs with PFRs, the greatest effect being observed with the combined vapour and condensed-phase active AlPi/MPP.Two polymeric brominated flame retardants (BrFRs) were selected: brominated polystyrene, (BrPS) and poly(pentabromopolybenzl acrylate (BrPBz), and were compounded with AlW, ZnW and SnW into PA66. AlW displayed significant antagonism with both BrFRs while SnW and ZnW both showed promising improvements in terms of UL94 and LOI performance and significant reductions in cone-derived PHRR values. These results were replicated at various differing Sn:Br and Zn: Br molar ratios.Mechanisms of action of AlW, SnW and ZnW were studied with both PFRs and BrFRs using TGAFTIR and analysis of cone-derived chars. Based on the detailed analysis, the inherent action of these tungstates alone was proposed to be condensed phase, Lewis-acid catalysed cross-linking of PA66), thereby promoting the formation of char, whereas any vapour phase activity for the FRCs such as SnPhPO3 and SnH2PO3 could originate from volatilisation of either phosphorus or metal (Sn, Fe, Zn) acting as vapour-phase radical quenching agents. With regards to the specific mechanism of action of the tungstates with other flame retardant elements, in combination with BrFRs, formation of metal halides and oxyhalides are proposed to contribute to condensed-phase char promotion and vapour-phase radical quenching. In combination with PFRs, increased chain cross-linking promotes the formation of greater char, stabilised by the presence of phosphorus groups and metal oxide residues, coupled with vapour phase activity inherent to AlPi.In conclusion, of 180 FRCs synthesised and screened for potential FR behaviour in PA66, the tungstates in particular were observed to possess both some level of flame retardant behaviour as well as function as synergists with selected phosphorus- and bromine-containing flame retardants. A method for screening future FRCs was also developed
Overcoming barriers to recruiting ethnic minorities to mental health research: a typology of recruitment strategies
No full textBackground:The ethnic minority population in developed countries is increasing over time. These groups are at higher risk of mental illness and demonstrate lower participation in research. Published evidence suggests that multiple factors like stigma, lack of trust, differences in explanatory models, logistical issues and lack of culturally aware researchers act as barriers to ethnic minority recruitment into mental health research. To reduce inequalities in participation, there is a need to devise innovative and culturally sensitive recruitment strategies. It is important that researchers share their experience of employing these strategies so that ethnic minority participation can be facilitated.Methods:We previously published a systematic review of barriers to recruiting ethnic minority participants into mental health research. The nine papers included in our prior review formed the basis for developing a typology of barriers to recruiting ethnic minorities into mental health research. This typology identified 33 barriers, described under five themes. We further extracted data on the strategies used to overcome these recruitment barriers, as described in the included studies.Results:The strategies employed by the authors could be matched to all but two barriers (psychopathology/substance misuse and limited resource availability). There was evidence that multiple strategies were employed, and that these depended upon the population, clinical set-up and resources available.Conclusions:This typology of strategies to overcome barriers to recruiting ethnic minorities provides guidance on achieving higher rates of recruitment. It is important that researchers plan to deploy these strategies well in advance of initiating recruitment. Whilst adopting these strategies, the authors have not been able to quantify the positive impact of these strategies on recruitment. The typology should encourage researchers to employ these strategies in future research, refine them further and quantitatively evaluate their impact
Rethinking informal learning
No full textInformal learning has been always an important source of knowledge, perhaps the most important at the workplace, but its own informal nature has caused difficulties to be recognized and introduced in the "official" ways of training and certification. TEEM conference has paid special attention to the problems associated with informal learning from the first edition of this event, and now this track continues with this significant tradition with the aim of rethinking the informal learning basis