Failure of elastic‐plastic core–shell microcapsules under compression

Characterization of the failure behavior of microcapsules is extremely important to control the release of their core actives by mechanical forces. The strain and stress of elastic‐plastic uninflated core–shell microcapsules at failure (rupture or bursting) has been determined using finite element modeling (FEM) and micromanipulation compression experiments. The ductile failure of polymeric microcapsules at high deformations is considered to occur when the maximum strain in the shell exceeds a critical strain, resulting in their rupture. FEM has been used to determine the maximum strains present in the capsule wall at different deformations for three types of shell material: elastic, elastic—perfectly plastic and elastic—perfectly plastic with strain hardening at large strains. The results obtained were used to determine the failure strain and stress of melamine‐formaldehyde microcapsules, with average population values of ～0.48 and ～350 MPa, respectively. Thus, the elastic‐plastic stress–strain relationship has been determined for the core–shell microcapsules tested. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Development of a hydrogen fuelling infrastructure in the Northeast U.S.A.

Development of critical selection criteria was undertaken, identifying locations for possible hydrogen refuelling stations depending on population density, demographics and traffic density. This identified suitable locations for the initial installations of refuelling stations when the first hydrogen fuel cell vehicles became commercially available. This was continued through the three time phases to implement an expanding network of refuelling stations to service demand and ensure consumer convenience.     

Increased Urinary IgA in Paediatric IgA Vasculitis Nephritis

IgA vasculitis (IgAV) is the most common form of paediatric vasculitis, with up to 50% of patients experiencing kidney inflammation. Much remains unknown about IgAV, but it is believed to arise due to galactose-deficient IgA1 promoting an auto-inflammatory response. This study assesses whether urinary IgA can be detected in children with IgAV to allow further evaluation of IgA1 and whether it has any relationship with nephritis. Urinary and serum IgA concentrations were measured using commercially available ELISA kits. Patients were grouped into IgAV nephritis (IgAVN) or IgAV without nephritis (IgAVwoN). Fifty-nine children were included: IgAVN n = 12, IgAVwoN n = 35, and healthy controls (HC) n = 12, with a mean age of 8.2 ± 4.1 years. Urinary IgA concentrations were statistically significantly higher in patients with IgAV (107.1 ± 136.3 μg/mmol) compared to HC (50.6 ± 26.3 μg/mmol; p = 0.027) and IgAVN (229.8 ± 226.3 μg/mmol) compared to both IgAVwoN (65.0 ± 37.8 μg/mmol; p = 0.002) and HC (p < 0.001). Urinary IgA concentrations were able to distinguish between renal status (AUC 0.838, 95%CI [0.704–0.973], p < 0.001) and did not correlate with proteinuria (r = 0.124; p = 0.407). Urinary IgA concentrations are increased in children with IgAVN, and it has the potential to act as a non-invasive biofluid to further evaluate nephritis in this disease.     

Synthesis of Unsaturated Polyester Resins from Various Bio-Derived Platform Molecules

Utilisation of bio-derived platform molecules in polymer synthesis has advantages which are, broadly, twofold; to digress from crude oil dependence of the polymer industry and secondly to reduce the environmental impact of the polymer synthesis through the inherent functionality of the bio-derived platform molecules. Bulk polymerisation of bio-derived unsaturated di-acids has been employed to produce unsaturated polyester (UPEs) which have been analysed by GPC, TGA, DSC and NMR spectroscopy, advancing on the analysis previously reported. UPEs from the diesters of itaconic, succinic, and fumaric acids were successfully synthesised with various diols and polyols to afford resins of M_N 480–477,000 and T_g of −30.1 to −16.6 °C with solubilities differing based on starting monomers. This range of properties allows for many applications and importantly due to the surviving Michael acceptor moieties, solubility and cross-linking can be specifically tailored, post polymerisation, to the desired function. An improved synthesis of itaconate and succinate co-polymers, via the initial formation of an itaconate bis-diol, is also demonstrated for the first time, resulting in significantly improved itaconate incorporation.     

The contribution of human factors to accidents in the offshore oil industry

Accidents such as the Piper Alpha disaster illustrate that the performance of a highly complex socio-technical system, is dependent upon the interaction of technical, human, social, organisational, managerial and environmental factors and that these factors can be important co-contributors that could potentially lead to a catastrophic event. The purpose of this article is to give readers an overview of how human factors contribute to accidents in the offshore oil industry. An introduction to human errors and how they relate to human factors in general terms is given. From here the article discusses some of the human factors which were found to influence safety in other industries and describes the human factors codes used in accident reporting forms in the aviation, nuclear and marine industries. Analysis of 25 accident reporting forms from offshore oil companies in the UK sector of the North Sea was undertaken in relation to the human factors. Suggestions on how these accident reporting forms could be improved are given. Finally, this article describes the methods by which accidents can be reduced by focusing on the human factors, such as feedback from accident reporting in the oil industry, auditing of unsafe acts and auditing of latent failures.     

Focal-plane and aperture-plane heterodyne array receivers for millimeter-wave radioastronomy—A comparison

In this paper we consider the maximization of the throughput of a single large antenna, for two possible array configurations: focal plane imaging arrays and aperture plane phased arrays. We discuss trade-offs between the two types of array in terms of field of view, sampling efficiency and time to map, a source. We also discuss limits on the number of feed elements in an imaging array imposed by the deterioration in aperture efficiency off-axis.     

What college students really think about ethnic student organizations.

In this study, the authors examined European, Hispanic, and African American college students' attitudes toward ethnic student organizations (ESOs). Based on data from Study 1 (N = 750), it was found that students across ethnic groups expressed uncertainty about whether ESOs were beneficial/necessary, fair/acceptable, and about their interest in joining an ESO. As a group, Hispanic and African American students did not believe that ESOs contributed to racial or ethnic separatism on campus, whereas European Americans expressed uncertainty about that possibility. In Study 2, a separate sample of students (N = 631) was randomly assigned to read the mission statement of a White, Hispanic, or African American ESO. Consistent with asymmetry theory, students in general judged the White American ESO as significantly less beneficial/necessary, less fair/acceptable, and as contributing more to racial/ethnic separatism than the Hispanic and African American ESOs. European, Hispanic, and African American students viewed their own ESO most favorably, although European American students were more consistent in their appraisals of ESOs irrespective of the ethnic focus of the ESO. Implications of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of chlorophyll pigments in ripening canola seed (Brassica napus)

This study characterizes the chlorophyll pigments in ripeningBrassica napus seed. Seed samples, collected weekly as the crop ripened, were analyzed by high-performance liquid chromatography to characterize chlorophyll pigment composition. Chlorophyll A, chlorophyll B, pheophytin A and pheophytin B were the predominant pigments, while pheophorbide A, methylpheophorbide A and pyropheophytin A were minor components. No differences in pigment composition were observed between the three cultivars tested or between early and late seeding dates. There were differences in pigment composition between the two years of the study, which may result either from seed aging during storage or from environmental influences. Pigment composition was dependent on seed maturity, with physiologically mature green seeds containing both chlorophylls and pheophytins, but fully mature seeds containing only chlorophylls. Pheophytins and the minor components appeared transiently, presumably formed from the chlorophylls and subsequently degraded. The ratio of chlorophyll A/B increased during seed ripening, with fully mature canola seed having a chlorophyll A/B ratio twice that of physiologically mature green seed. The “B” derivatives degraded faster than the “A” derivatives, suggesting enzymatic reactions. The initial steps in the chlorophyll breakdown pathway in canola seed appear to be: