Solution pH change in non-uniform alternating current electric fields at frequencies above the electrode charging frequency

AC Faradaic reactions have been reported as a mechanism inducing non-ideal phenomena such as flow reversal and cell deformation in electrokinetic microfluidic systems. Prior published work described experiments in parallel electrode arrays below the electrode charging frequency (f_c), the frequency for electrical double layer charging at the electrode. However, 2D spatially non-uniform AC electric fields are required for applications such as in plane AC electroosmosis, AC electrothermal pumps, and dielectrophoresis. Many microscale experimental applications utilize AC frequencies around or above f_c. In this work, a pH sensitive fluorescein sodium salt dye was used to detect [H⁺] as an indicator of Faradaic reactions in aqueous solutions within non-uniform AC electric fields. Comparison experiments with (a) parallel (2D uniform fields) electrodes and (b) organic media were employed to deduce the electrode charging mechanism at 5 kHz (1.5f_c). Time dependency analysis illustrated that Faradaic reactions exist above the theoretically predicted electrode charging frequency. Spatial analysis showed [H⁺] varied spatially due to electric field non-uniformities and local pH changed at length scales greater than 50 μm away from the electrode surface. Thus, non-uniform AC fields yielded spatially varied pH gradients as a direct consequence of ion path length differences while uniform fields did not yield pH gradients; the latter is consistent with prior published data. Frequency dependence was examined from 5 kHz to 12 kHz at 5.5 V_pp potential, and voltage dependency was explored from 3.5 to 7.5 V_pp at 5 kHz. Results suggest that Faradaic reactions can still proceed within electrochemical systems in the absence of well-established electrical double layers. This work also illustrates that in microfluidic systems, spatial medium variations must be considered as a function of experiment time, initial medium conditions, electric signal potential, frequency, and spatial position.     

Inducing chemotactic and haptotactic cues in microfluidic devices for three-dimensional in vitro assays

Microfluidic devices allow for the production of physiologically relevant cellular microenvironments by including biomimetic hydrogels and generating controlled chemical gradients. During transport, the biomolecules interact in distinct ways with the fibrillar networks: as purely diffusive factors in the soluble fluid or bound to the matrix proteins. These two main mechanisms may regulate distinct cell responses in order to guide their directional migration: caused by the substrate-bound chemoattractant gradient (haptotaxis) or by the gradient established within the soluble fluid (chemotaxis). In this work 3D diffusion experiments, in combination with ELISA assays, are performed using microfluidic platforms in order to quantify the distribution of PDGF-BB and TGF-β₁ across collagen and fibrin gels. Furthermore, to gain a deeper understanding of the fundamental processes, the experiments are reproduced by computer simulations based on a reaction-diffusion transport model. This model yields an accurate prediction of the experimental results, confirming that diffusion and binding phenomena are established within the microdevice.     

体育规则：足球规则修改与集体项目规则的比较研究

本文以法学视角,尤其是国际法视角,通过研读规则文本的方式,对足球规则的演进进行分析,并且揭示一些目前体育法领域关注的问题:体育法(lex sportiva)确实存在,包含了公法部分(国际公约、国家立法)和私法部分(体育规则);体育规则(Laws of the game)是体育法的核心,包括国家、地区以及全球范围内各级体育主管部门的章程与条例;项目规则是体育法的另一个重要核心,作者以足球为例,论证了为什么项目规则也是法的问题。     

‘Motivate’: the effect of a Football in the Community delivered weight loss programme on over 35-year old men and women’s cardiovascular risk factors

The purpose of this study was to examine whether an innovative, inclusive and integrated 12-week exercise, behaviour change and nutrition advice-based weight management programme could significantly improve the cardiovascular risk factors of overweight and obese men and women over the age of 35. One hundred and ninety-four men and 98 women (mean age?=?52.28?±?9.74 and 51.19?±?9.04) attending a community-based intervention delivered by Notts County Football in the Community over one year, took part in the study. Height (m), weight (kg), fitness (meters covered during a 6?min walk) and waist circumference (cm) were measured at weeks 1 and 12 as part of the intervention. Changes in body weight, waist circumference and fitness for men and women were measured by a 2-way repeated measures ANOVA, with significance set to p?<?0.05.Weight, waist circumference and fitness significantly improved over time in both men (4.96?kg, 6.29?cm, 70.22?m; p?<?0.05) and women (4.26?kg, 5.90?cm, 35.29?m; p?<?0.05). The results demonstrated that the FITC lead weight loss intervention was successful in significantly improving cardiovascular risk factors in both men and women. In particular, the weight loss reductions achieved were comparable to those seen in similar, more costly men-only programmes. This is the first study to demonstrate the efficacy of such an intervention in an inclusive, mixed gender programme and more specifically, in women.     

The minimizing style: perceptions of psychological abuse and quality of past and current relationships

OBJECTIVE: The goals of this current project were to expand and elaborate on the results of Varia, Abidin, and Dass' (1996) study to better understand what historical parenting factors may contribute in creating a "Minimizing" perception of childhood psychological abuse. A second objective included examining the association between perceptual styles and adult ratings of adult relationship satisfaction. METHOD: Ninety individuals from a non-clinical adult sample completed self-report questionnaires regarding psychological maltreatment and adult relationship satisfaction. Three groups were created and compared using analysis of variance. The groups were (I) "Non-Abused," consistent reporters of no abuse; (II) "Acknowledgers," consistent reporters of abuse; and (III) "Minimizers," reporters of abuse, but do not label themselves as having been abused. RESULTS: Results indicated a continuum effect with the Non-Abused individuals reporting the highest level of maternal warmth and affection, the Acknowledgers reporting the lowest, with the Minimizers in the middle. The Non-Abused group reported the healthiest adjustment in terms of adult relationship satisfaction. While Minimizers and Acknowledgers reported similar levels of psychologically abusive experiences, Acknowledgers reported more difficulties with adult relationships. CONCLUSIONS: This study highlights the importance of studying Minimizers, a group which describes abusive events but minimizes the meaning and scope of these experiences. The relatively higher levels of maternal care which the Minimizers reported is hypothesized to be associated with their perceptions that they were not abused and acted as a protective factor associated with better quality adult relationships. The varying degrees of nurturance and care in the early family environment of abused individuals is speculated to be associated with distinct perceptual styles.     

MEDLINE services to the developing countries.

Supplying MEDLINE services to a widely dispersed user population in the developing countries creates numerous problems not encountered by other MEDLINE centres. The inability to interact with the user complicates system promotion and makes search formulation sometimes a gamble. Nevertheless, an evaluation survey has shown high user satisfaction. Of great concern is the still inadequate solution of document delivery. Near-term objectives are the broadening of geographic coverage and the integration of search processing with supporting hard copy supply.