Solution Behaviour of Polyethylene Oxide, Nonionic Gemini Surfactants

In recent years there has been increasing interest in novel forms of surfactants. Of particular interest are gemini surfactants, which consist of two conventional surfactants joined by a spacer at the head groups, as they exhibit lower critical micelle concentrations than can be achieved by conventional surfactants. In this work, the self-assembly behaviour of several nonionic gemini surfactants with polyethylene oxide head groups (GemnEm, where n (= 20) is the number of carbons per tail and m (= 10, 15, 20 and 30) is the number of ethylene oxides per head group) were investigated. The Critical Micelle Concentrations (CMCs) were measured using a fluorescence probe technique. The CMCs are all ~2 x 10?7 M, with almost no variation with m. The CMCs are several orders of magnitude lower than conventional C12Em nonionic surfactants. The mixing behaviour of the gemini surfactants with conventional surfactants was also studied. They obeyed ideal mixing behaviour with both ionic and nonionic surfactants. Micelle morphologies were studied using Small Angle Neutron Scattering. The gemini surfactants with the larger head groups (i.e. Gem20E20 and Gem20E30) formed spherical micelles. Gem20E15 showed strong scattering at low Q, characteristic of elongated micelles. As the temperature was increased towards the cloud point, the scattering approached the Q-1 dependence predicted for infinite, straight rods. The existence of anisotropic micelles was supported by the viscosity of Gem20E15, which increases by several orders of magnitude on heating towards its cloud point. Phase behaviour was determined using Diffusive Interfacial Transport coupled to near-infrared spectroscopy. Much of the behaviour of these systems is similar to conventional nonionic surfactants. For example, Gem20E10 forms a dilute liquid isotropic phase (W) coexisting with a concentrated lamellar phase (La) at around room temperature and forms a sponge phase at higher temperatures. This is similar to the behaviour of C12E3 and C12E4. The other surfactants studied are all quite soluble in water and form liquid isotropic and hexagonal phases from room temperature. At higher concentrations Gem20E15 formed a cubic and then a lamellar phase while Gem20E20 formed a cubic phase and then an intermediate phase. This is also comparable to the phase behaviour of conventional nonionic surfactants except the intermediate phase, which is often only observed for surfactant systems with long alkyl tails

The role and relevancy of the black church in today\u27s society

The purpose of this study is to gather information about the role and the relevancy of the black church in regards to social issues in today\u27s society. The significance of the study reflects many attitudes of the African-American community. It gives greater insight on the questions surrounding the differing roles of the black church. This study also gives some insight to churches on what the participants say makes the church relevant to them. With this information, churches can become more aware and capable of meeting the needs of the people in the community; The methods used were an in-depth qualitative interview process consisting of exploratory insights from the participants into what they believed the role and relevancy of the black church is today. Taped interviews, written interviews, note-taking, and open-ended guiding questions were also used. The sample size of 25 people and five local pastors included people in eight churches located in the Las Vegas area. The people interviewed were African-American males and females age 18 and above, with various education levels, family structures, and backgrounds. (Abstract shortened by UMI.)

Vehicular sources in acoustic propagation experiments

One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range

Streamlining Collaborative Agreements in an e-Research World

On 22 January 2008, the Australian Minister for Innovation, Science and Research announced a review of the ‘National Innovation System’2 which intends to analyse the Australian innovation system and to ‘build innovation capacity by bringing sectors, institutions and individuals together’.3 To achieve innovation through this style of collaboration, the different actors will inevitably need to engage with technologically enhanced research methods and practices known broadly as e-Research. The rapidly emerging e-Research landscape promises to accelerate the discovery of knowledge, to increase the access and dissemination of data and to provide the opportunity for the international and serendipitous exchange of knowledge. 4 The law will play a central role in this environment. It acts like an infrastructure to shape the flow of knowledge. In many collaborative projects, the negotiation and completion of agreements which outline the project are not only critical, but also represent one of the biggest barriers to effective collaboration. The purpose of this chapter is to consider how the negotiation and contractual frameworks for research can be streamlined to accommodate the coming era of collaborative e-Research

Optimizing multi-dimensional terahertz imaging analysis for colon cancer diagnosis

Peer reviewedPublisher PD

Payout Policy in the 21st Century

We survey 384 CFOs and Treasurers, and conduct in-depth interviews with an additional two dozen, to determine the key factors that drive dividend and share repurchase policies. We find that managers are very reluctant to cut dividends, that dividends are smoothed through time, and that dividend increases are tied to long-run sustainable earnings but much less so than in the past. Rather than increasing dividends, many firms now use repurchases as an alternative. Paying out with repurchases is viewed by managers as being more flexible than using dividends, permitting a better opportunity to optimize investment. Managers like to repurchase shares when they feel their stock is undervalued and in an effort to affect EPS. Dividend increases and the level of share repurchases are generally paid out of residual cash flow, after investment and liquidity needs are met. Financial executives believe that retail investors have a strong preference for dividends, in spite of the tax disadvantage relative to repurchases. In contrast, executives believe that institutional investors as a class have no strong preference between dividends and repurchases. In general, management views provide at most moderate support for agency, signaling, and clientele hypotheses of payout policy. Tax considerations play only a secondary role. By highlighting where the theory and practice of corporate payout policy are consistent and where they are not, we attempt to shed new light on important unresolved issues related to payout policy in the 21st century.

The impact of a workplace catering initiative on dietary intakes of salt and other nutrients: a pilot study

Owing to modern lifestyles, individuals are dependent on out-of-home eating. The catering sector can have a pivotal role in influencing our food choices. The objective of the present study was to examine the impact of a structured catering initiative on food choices in a public sector workplace setting

Assessing Graduate Student Needs and Structures of Support at Virginia Commonwealth University

The purpose of this multi-case study was to explore how the institutional landscape is designed to support graduate student success at Virginia Commonwealth University (VCU), a large, public, urban, R1 research university. The study included review of existing literature on the various factors that contribute to or limit graduate student success at institutions across the country. A major aim of this study was to collect qualitative data from participants with a key stake in this issue, including enrolled graduate students, and faculty/staff supporting graduate (master’s and doctoral) programs at VCU. Participants included 39 graduate students and 23 institutional stakeholders. All graduate students were invited to participate by email, with 39 final graduate students participating in seven, 60-90 minute focus groups of 6-8 students via Zoom with two members of the research team. Institutional stakeholders, with roles as full-time faculty or staff members at the university, were identified through institutional mapping and website review and invited via email, participated in 60-minute, one-on-one interviews via Zoom with one member of the research team. The study resulted in data coalescing around larger themes of graduate student support, factors promoting graduate student success, and challenges and barriers to success. A benchmarking comparison of VCU alongside peer institutions related to standards for graduate studies further identified areas of interest in 1) Programs and Services for Student Success, 2) Social Justice and Accessibility, 3) Collaboration, and 4) Assessment and Strategic Planning. Findings from the study indicated that, although VCU students appear to excel academically, there are challenges to graduate students balancing the demands of academic rigor with other obligations including, familial support, mental health and wellbeing needs, financial obligations, and social engagement. VCU students will continue to need increased support for funding, social connections, and referrals to appropriate resources. These findings have significant implications for structuring support for graduate students both at Virginia Commonwealth University and could influence institutions similarly situated across the country

A systematic review and meta-regression analysis of the vitamin D intake-serum 25-hydroxyvitamin D relationship to inform European recommendations

The present study used a systematic review approach to identify relevant randomised control trials (RCT) with vitamin D and then apply meta-regression to explore the most appropriate model of the vitamin D intake–serum 25-hydroxyvitamin D (25(OH)D) relationship to underpin setting reference intake values. Methods included an updated structured search on Ovid MEDLINE; rigorous inclusion/exclusion criteria; data extraction; and meta-regression (using different model constructs). In particular, priority was given to data from winter-based RCT performed at latitudes >49•58°N (n 12). A combined weighted linear model meta-regression analyses of natural log (Ln) total vitamin D intake (i.e. diet and supplemental vitamin D) versus achieved serum 25(OH)D in winter (that used by the North American Dietary Reference Intake Committee) produced a curvilinear relationship (mean (95% lower CI) serum 25(OH)D (nmol/l) = 9•2 (8•5) Ln (total vitamin D)). Use of non-transformed total vitamin D intake data (maximum 1400 IU/d; 35µg/d) provided for a more linear relationship (mean serum 25(OH)D (nmol/l) = 0•044 × (total vitamin D) + 33•035). Although inputting an intake of 600 IU/d (i.e. the RDA) into the 95% lower CI curvilinear and linear models predicted a serum 25(OH)D of 54•4 and 55•2 nmol/l, respectively, the total vitamin D intake that would achieve 50 (and 40) nmol/l serum 25(OH)D was 359 (111) and 480 (260) IU/d, respectively. Inclusion of 95% range in the model to account for inter-individual variability increased the predicted intake of vitamin D needed to maintain serum 25(OH)D ≥50 nmol/l to 930 IU/d. The model used to describe the vitamin D intake–status relationship needs to be considered carefully when setting new reference intake values in Europe

Group problem-solving skills training for self-harm: randomised controlled trial

Background: Rates of self-harm are high and have recently increased. This trend and the repetitive nature of self-harm pose a significant challenge to mental health services. Aims: To determine the efficacy of a structured group problem-solving skills training (PST) programme as an intervention approach for self-harm in addition to treatment as usual (TAU) as offered by mental health services. Method: A total of 433 participants (aged 18-64 years) were randomly assigned to TAU plus PST or TAU alone. Assessments were carried out at baseline and at 6-week and 6-month follow-up and repeated hospital-treated self-harm was ascertained at 12-month follow-up. Results: The treatment groups did not differ in rates of repeated self-harm at 6-week, 6-month and 12-month follow-up. Both treatment groups showed significant improvements in psychological and social functioning at follow-up. Only one measure (needing and receiving practical help from those closest to them) showed a positive treatment effect at 6-week (P = 0.004) and 6-month (P = 0.01) follow-up. Repetition was not associated with waiting time in the PST group. Conclusions: This brief intervention for self-harm is no more effective than treatment as usual. Further work is required to establish whether a modified, more intensive programme delivered sooner after the index episode would be effective