Numerical investigations of bubbles rising in water

The hydrodynamics of rising air bubbles in water filled bubble columns are examined using a transient numerical model following the Euler-Euler method. In this particular case the bubble-size distribution is assumed to be mono-disperse and the influence of this assumption on the specific mass-transfer area is discussed. Additionally, the influence of the bubble size is discussed with regard to the mass-transfer area, the air volume-fraction, and the axial air velocity profile. To validate the numerical model, experimental results from tomographic measurements at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) are used. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Developing the roots of modelling conceptions: ‘mathematical modelling is the life of the world’

A study conducted with 25 Year 6 primary school students investigated the potential for a short classroom intervention to begin the development of a Modelling conception of mathematics on the way to developing a sense of mathematics as a way of thinking about life. The study documents the developmental roots of the cognitive activity, actions and conceptions of both modelling and mathematics that these beginners to modelling displayed. Understanding the conceptions of mathematics that students might hold or be developing and how these can be influenced in early schooling are essential ingredients in any plans for introducing modelling seriously into primary school classrooms. The majority of the students (22/25) were identified as displaying a developing conception of modelling as a way of problem handling. The three other students displayed the developmental roots of a way of understanding the world conception of modelling. These three students also displayed a Modelling conception of mathematics with one showing indications of developing towards a Life conception of mathematics.     

Utilization of PVPA and its effect on the material properties and biocompatibility of PVA electrospun membrane

This study aims to investigate on the effect of the addition of polyvinylphosphonic acid (PVPA) on the material properties and biocompatibility of a polyvinyl alcohol (PVA) polymer tissue engineering scaffold fabricated by electrospinning process. Stabilization of the membranes was carried out by heat application. Fourier transform infrared spectroscopy confirmed the presence of P?O bonds and P–OH bonds and increase in the atomic percentage of phosphorus in Energy Dispersive Spectroscopy (EDS) indicated successful incorporation of PVPA to the PVA. Scanning electron microscope fiber morphology and microstructure showed that addition of PVPA reduced the average fiber diameter of the scaffold. After 1 hr of phosphate buffered saline immersion, scaffolds were observed to swell to almost 200% of their original weight. Increased tensile strength was observed at 0.1% PVPA addition but reduced values were observed when the concentration was greater than 0.1%. Cytocompatibility was examined with M3CT3‐E1 preosteoblast cells through cell viability after exposure to extract solutions and Live/Dead cell staining. Cell proliferation was quantified by MTT assay; cell adhesion was visualized by scanning electron microscope and confocal microscopy images. Bone regeneration was also observed and quantified using histomorphometric analysis and histological staining methods after implantation in rat calvarium for 4 weeks. Copyright © 2013 John Wiley & Sons, Ltd.     

Attitudes about genetics in underserved, culturally diverse populations

OBJECTIVE: New medical discoveries regarding genetic susceptibility to common chronic diseases, and the decoding of the human genome have increased public attention to genetics. What information is understood and what attitudes exist towards genetics and genetic research have not been well examined in underserved, culturally diverse communities. METHODS: To better understand attitudes and beliefs towards genetics and genetic testing in these groups, we conducted eight focus groups with 55 patients and health care workers in New York City and Westchester, N.Y., in English, Spanish, and Chinese. RESULTS: Focus group participants had limited understanding about genetics or genetic testing. Newborn screening was the least-known genetic issue, even among health care workers. Regardless of their cultural group, most participants expressed a desire for more information about genetics and genetic tests. Latinos and Chinese participants generally expressed positive attitudes towards genetic studies and genetic testing, with the possibility of preventing diseases cited as the main advantage. Black Americans and Non-Hispanic Whites reported mixed feelings about genetic research and genetic testing. Concerns expressed included: anxiety before receiving test results or waiting for a disease to develop, fear of genetic discrimination by health and life insurance companies and employers, not having the financial means to deal with genetic diseases in themselves or a sick child, concern that children and adults are having too many tests. Black Americans expressed the most concern for possibly harmful use of genetic information. CONCLUSIONS: Minority populations of diverse cultures have limited knowledge about genetics and genetic testing, would like to have more information, and are not well reached by the current educational approaches. Participants knew the least about newborn screening, a test that is mandatory in the New York State. While genetic knowledge by minority populations was perhaps not different from the level of knowledge of consumers in general, minority populations are at particular risk of being left behind because of historically poor access to information and services.     

Unitary Units Satisfying a Group Identity

Let K be a nonabsolute field of characteristic p ≠ 2, G a locally finite group and KG its group algebra. Let ?: KG → KG denote the K-linear extension of an involution ? defined on G. In this article, we prove that if the subgroup 𝒰_?(KG), i.e., the ?-unitary units of KG, satisfies a group identity, then KG satisfies a polynomial identity. Moreover, in case the prime radical of KG is nilpotent, we characterize the groups G for which 𝒰_?(KG) satisfies a group identity.     

Implementation of IBL in Europe from an Australasian perspective

In this paper the situation in Australasia with respect to research, curricula and practice in inquiry-based learning in mathematics education is examined. As an organising frame the work of researchers in the Mathematics Education Research Group of Australasia (MERGA) was examined for points of intersection with several of the papers that have arisen from the international PRIMAS project, one of several projects funded by the European Union which follow the recommendations of the Rocard Report (Rocard et al. 2007). Although MERGA services researchers in countries such as Singapore in addition to Australia and New Zealand, a survey of outputs of members showed that the latter two countries had more of a tradition of inquiry-based learning practices and research in mathematics education than did Asian countries under the MERGA umbrella such as Singapore. For this reason the focus here is on mathematics education in the schools in these two countries and the classroom research in them that extends or complements the research or issues raised in other papers in this issue of ZDM.     

Anionic Polysaccharides as Templates for the Synthesis of Conducting Polyaniline and as Structural Matrix for Conducting Biocomposites

A green chemoenzymatic pathway for the synthesis of conducting polyaniline (PANI) composites is presented. Laccase‐catalyzed polymerization in combination with anionic polysaccharides is used to produce polysaccharide/PANI composites, which can be processed into flexible films or coated onto cellulose surfaces. Different polysaccharide templates are assessed, including κ‐carrageenan, native spruce O‐acetyl galactoglucomannan (GGM), and TEMPO‐oxidized cellulose and GGM. The resulted conducting biocomposites derived from natural materials provide a broad range of potential applications, such as in biosensors, electronic devices, and tissue engineering.

     

MR elastography of the head and neck: Driver design and initial results

Purpose

The purpose was to describe the design and fabrication of a driver suitable for magnetic resonance elastography (MRE) of the head and neck and to assess its performance in evaluating human parotid gland, lymph nodes and thyroid at 3.0 T.

Materials and methods

A head and neck driver was fabricated using a commercial transducer, headrest mould and piston extension. Driver performance was tested using a motion-sensitized spin-echo MRE pulse sequence. Six healthy volunteers and three patients (two metastatic nodes and one papillary carcinoma) were evaluated using MRE. Viscoelastic maps were computed to obtain storage modulus (G’) and loss modulus (G”) of the normal parotid and thyroid, metastatic node and thyroid cancer. Reproducibility was assessed by coefficient of variation.

Results

All subjects completed MRE examination without discomfort. Initial G’ and G” values were as follows: normal parotid gland, 1.12 kPa and 0.48 kPa; thyroid, 0.58 kPa and 0.42 kPa; metastatic node, 0.66 kPa and 0.58 kPa; and thyroid cancer, 0.17 kPa and 0.28 kPa. Based on parotid data, the coefficient of variation for G’ and G” was 4.7% and 9.8%.

Conclusion

A new MRE driver for head and neck was successfully implemented, and our initial results suggested the device was suitable for the mechanical assessment of tissues in the head and neck.