Macroscopic modelling of the surface tension of polymer-surfactant systems

Polymer-surfactant mixtures are increasingly being used in a wide range of applications. Weakly-interacting systems, such as SDS/PEO and SDS/PVP, comprise ionic surfactants and neutral polymers, while strongly-interacting systems, such as SDS/POLYDMDAAC and C12TAB/NaPSS, comprise ionic surfactants and oppositely charged ionic polymers. The complex nature of interactions in the mixtures leads to interesting and surprising surface tension profiles as the concentrations of polymer and surfactant are varied. The purpose of our research has been to develop a model to explain these surface tension profiles and to understand how they relate to the formation of different complexes in the bulk solution. In this paper we shouw how an existing model based on the law of mass action can be extended to model the surface tension of weakly-interacting systems, and we also extend it further to produce a model for the surface tension of strongly interacting systems. Applying the model to a variety of strongly-interacting systems gives remarkable agreement with the experimental results. The model provides a sound theoretical basis for comparing and contrasting the behaviour of different systems and greatly enhances our understanding of the features observed

Developmental programming by maternal obesity in 2015: Outcomes, mechanisms, and potential interventions.

This article is part of a Special Issue "SBN 2014". Obesity in women of child-bearing age is a growing problem in developed and developing countries. Evidence from human studies indicates that maternal BMI correlates with offspring adiposity from an early age and predisposes to metabolic disease in later life. Thus the early life environment is an attractive target for intervention to improve public health. Animal models have been used to investigate the specific physiological outcomes and mechanisms of developmental programming that result from exposure to maternal obesity in utero. From this research, targeted intervention strategies can be designed. In this review we summarise recent progress in this field, with a focus on cardiometabolic disease and central control of appetite and behaviour. We highlight key factors that may mediate programming by maternal obesity, including leptin, insulin, and ghrelin. Finally, we explore potential lifestyle and pharmacological interventions in humans and the current state of evidence from animal models.NCP holds a Wellcome Trust PhD studentship; SEO is a member of the MRC Metabolic Diseases Unit and is funded by MRC grant MC_UU_12012/4.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.yhbeh.2015.06.01

Amniotic fl uid embolism in an HIV-positive parturient

We present a case of a parturient infected with human immunode ciency virus, who developed amniotic fluid embolism during the delivery of her twins by elective Caesarean section. Our management and the available literature are briefly discussed, and consideration is given to a possible association between the two pathologies.Keywords: amniotic fluid embolism; anaphylaxis; human immunode  ciency viru

Emerging trends in polymerization-induced self-assembly

In this Perspective, we summarize recent progress in polymerization-induced self-assembly (PISA) for the rational synthesis of block copolymer nanoparticles with various morphologies. Much of the PISA literature has been based on thermally initiated reversible addition–fragmentation chain transfer (RAFT) polymerization. Herein, we pay particular attention to alternative PISA protocols, which allow the preparation of nanoparticles with improved control over copolymer morphology and functionality. For example, initiation based on visible light, redox chemistry, or enzymes enables the incorporation of sensitive monomers and fragile biomolecules into block copolymer nanoparticles. Furthermore, PISA syntheses and postfunctionalization of the resulting nanoparticles (e.g., cross-linking) can be conducted sequentially without intermediate purification by using various external stimuli. Finally, PISA formulations have been optimized via high-throughput polymerization and recently evaluated within flow reactors for facile scale-up syntheses

The kinetics of surfactant desorption at the air–solution interface

The kinetics of desorption of the anionic surfactant sodium dodecylbenzene sulfonate at the air–solution interface have been studied using neutron reflectivity (NR). The experimental arrangement incorporates a novel flow cell in which the subphase can be exchanged (diluted) using a laminar flow whilst the surface region remains unaltered. The kinetics of the desorption is relatively slow and occurs over many tens of minutes compared with the dilution timescale of approximately 10–30 minutes. A detailed mathematical model, in which the rate of the desorption is determined by transport through a near-surface diffusion layer into a diluted bulk solution below, is developed and provides a good description of the timedependent adsorption data.\ud \ud A key parameter of the model is the ratio of the depth of the diffusion layer, Hc , to the depth of the fluid, Hf, and we find that this is related to the reduced Péclet number, Pe*, for the system, via Hc/Hf, = C/Pe* 1/ 2 . Although from a highly idealised experimental arrangement, the results provide an important insight into the ‘rinse mechanism’, which is applicable to a wide variety of domestic and industrial circumstances

Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies

By reducing energy density, low-energy sweeteners (LES) might be expected to reduce energy intake (EI) and body weight (BW). To assess the totality of the evidence testing the null hypothesis that LES exposure (versus sugars or unsweetened alternatives) has no effect on EI or BW, we conducted a systematic review of relevant studies in animals and humans consuming LES with ad libitum access to food energy. In 62 of 90 animal studies exposure to LES did not affect or decreased BW. Of 28 reporting increased BW, 19 compared LES with glucose exposure using a specific ‘learning’ paradigm. Twelve prospective cohort studies in humans reported inconsistent associations between LES use and Body Mass Index (-0.002 kg/m2/year, 95%CI -0.009 to 0.005). Meta-analysis of short- term randomized controlled trials (RCTs, 129 comparisons) showed reduced total EI for LES- versus sugar-sweetened food or beverage consumption before an ad libitum meal (-94 kcal, 95%CI -122 to -66), with no difference versus water (-2 kcal, 95%CI -30 to 26). This was consistent with EI results from sustained intervention RCTs (10 comparisons). Meta-analysis of sustained intervention RCTs (4 weeks to 40 months) showed that consumption of LES versus sugar led to relatively reduced BW (nine comparisons; -1.35 kg, 95%CI –2.28 to - 0.42), and a similar relative reduction in BW versus water (three comparisons; -1.24 kg, 95%CI –2.22 to -0.26). Most animal studies did not mimic LES consumption by humans, and reverse causation may influence the results of prospective cohort studies. The preponderance of evidence from all human RCTs indicates that LES do not increase EI or BW, whether compared with caloric or non-caloric (e.g., water) control conditions. Overall, the balance of evidence indicates that use of LES in place of sugar, in children and adults, leads to reduced EI and BW, and possibly also when compared with water

Clean Home-Delivery in Rural Southern Tanzania: Barriers, Influencers, and Facilitators

The study explored the childbirth-related hygiene and newborn care practices in home-deliveries in Southern\ud Tanzania and barriers to and facilitators of behaviour change. Eleven home-birth narratives and six focus group discussions were conducted with recently-delivering women; two focus group discussions were conducted with birth attendants. The use of clean cloth for delivery was reported as common in the birth narratives; however, respondents did not link its use to newborn’s health. Handwashing and wearing of gloves by birth attendants varied and were not discussed in terms of being important for newborn’s health, with few women giving reasons for this behaviour. The lack of handwashing and wearing of gloves was most commonly linked to the lack of water, gloves, and awareness. A common practice was the insertion\ud of any family member’s hands into the vagina of delivering woman to check labour progress before calling the birth attendant. The use of a new razor blade to cut the cord was near-universal; however, the cord was usually tied with a used thread due to the lack of knowledge and the low availability of clean thread. Applying something to the cord was near-universal and was considered essential for newborn’s health. Three hygiene practices were identified as needing improvement: family members inserting a hand into\ud the vagina of delivering woman before calling the birth attendant, the use of unclean thread, and putting\ud substances on the cord. Little is known about families conducting internal checks of women in labour, and more research is needed before this behaviour is targeted in interventions. The use of clean thread as cord-tie appears acceptable and can be addressed, using the same channels and methods that were used for successfully encouraging the use of new razor blade

Geographic disparities in the risk of perforated appendicitis among children in Ohio: 2001–2003

<p>Abstract</p> <p>Background</p> <p>Rural-urban disparities in health and healthcare are often attributed to differences in geographic access to care and health seeking behavior. Less is known about the differences between rural locations in health care seeking and outcomes. This study examines how commuting patterns in different rural areas are associated with perforated appendicitis.</p> <p>Results</p> <p>Controlling for age, sex, insurance type, comorbid conditions, socioeconomic status, appendectomy rates, hospital type, and hospital location, we found that patient residence in a rural ZIP code with significant levels of commuting to metropolitan areas was associated with higher risk of perforation compared to residence in rural areas with commuting to smaller urban clusters. The former group was more likely to seek care in an urbanized area, and was more likely to receive care in a Children's Hospital.</p> <p>Conclusion</p> <p>To our knowledge, this is the first study to differentiate rural dwellers with respect to outcomes associated with appendicitis as opposed to simply comparing "rural" to "urban". Risk of perforated appendicitis associated with commuting patterns is larger than that posed by several individual indicators including some age-sex cohort effects. Future studies linking the activity spaces of rural dwellers to individual patterns of seeking care will further our understanding of perforated appendicitis and ambulatory care sensitive conditions in general.</p

The one-component plasma: a conceptual approach

The one-component plasma (OCP) represents the simplest statistical mechanical model of a Coulomb system. For this reason, it has been extensively studied over the last forty years. The advent of the integral equations has resulted in a dramatic improvement in our ability to carry out numerical calculations, but came at the expense of a physical insight gained in a simpler analytic theory. In this paper we present an extension of the Debye-Hueckel (DH) theory to the OCP. The theory allows for analytic calculations of all the thermodynamic functions, as well as the structure factor. The theory explicitly satisfies the Stillinger-Lovett and, for small couplings, the compressibility sum rules, implying its internal self consistency.Comment: 28 pages, 5 Postscript figures, uses elsart.sty, accepted for publication in Physica