Hydroxyl Group Separation Distances in Anti-Freeze Compounds and Their Effects on Ice Nucleation

Since the discovery of biological antifreeze glycoproteins (AFGPs), which can inhibit ice nucleation, there has been considerable interest in understanding their mechanisms and mimicking them in synthetic polymers. In this study, we used molecular dynamics simulations of modified polyvinyl alcohol (PVA) compounds to show that the hydroxyl (OH) group distance is a key factor in whether certain compounds promote or inhibit ice nucleation. A hydroxyl distance smaller than ~2.8 Å but greater than ~7.1 Å in modified PVA (MPVA) compounds was associated with the promotion of ice nucleation, while a hydroxyl group separation distance of approximately ~5.0 Å was correlated with a delay in ice nucleation, owing to changes in the energy of the system. Thus, these results may help explain some of the mechanisms of current known anti-freeze compounds and may have implications for designing new anti-freeze compounds in the future.     

Overheating in care settings: magnitude,causes, preparedness and remedies

ABSTRACT

Research in UK and elsewhere has highlighted that older people are particularly vulnerable to negative health effects of overheating. This paper examines the magnitude, causes, preparedness and remedies for addressing the risk of summertime overheating in four case study residential care and extra-care settings across the UK, spanning different building types, construction and age. An interdisciplinary approach is adopted, drawing from building science and social science methods, including temperature monitoring, building surveys, and interviews with design and management teams. The findings suggest that overheating is a current and prevalent risk in the case study schemes, yet currently little awareness or preparedness exists to implement suitable and long-term adaptation strategies (e.g., external shading). There was a perception from designers to managers, that cold represents a bigger threat to older occupants’ health than excessive heat. A lack of effective heat management was found across the case studies that included unwanted heat gains from the heating system, confusion in terms of responsibilities to manage indoor temperatures, and conflicts between window opening and occupant safety. Given that care settings should provide protection against risks from cold and hot weather, design, management and care practices need to become better focused towards this goal.     

Gardening cyberspace—social media and hybrid spaces in the creation of food citizenship in the Bristol city-region,UK

Abstract

This paper conducts a detailed analysis of urban food and online networks in Bristol, UK. In particular, it examines social media postings of grass-roots food networks. Qualitative research identifies and analyses five core themes, from which two dominant discourses emerge. Analysis reinforces the multifunctional nature of city food but moves beyond dominant scholarly pre-occupations with nutrition and physical resources. Instead, the paper positions social and symbolic aspects as equal components within the convening power of food. To date, social media has been neglected in urban food research, although this is a space as well-tended and structured as the physical spaces it augments. The paper finds a relationship of limited collaboration between the grass-roots networks and the city council. While the former are dynamic and networked, the council adheres to a linear policy process that limits the scope of citizenship. The relationships examined here indicate implications for urban planning processes.     

Evaluation of the effects of sodium chloride,potassium sorbate,nisin and lysozyme on the probability of growth of Clostridium sporogenes

The aim of this study was to evaluate the combined effect of salt (sodium chloride, 0–8% w/v), sorbate (potassium sorbate, 0–4.5% w/v), nisin (0–500 ppm) and lysozyme (0–500 ppm) on the survival of Clostridium sporogenes as a non‐toxigenic surrogate of Clostridium botulinum in terms of the probability of growth by using a central composite rotatable design. The results indicated that salt and sorbate were the most effective factors in preventing the growth of Cl. sporogenes in high‐moisture (>95%) and low‐acid conditions. The probability of growth of Cl. sporogenes in broth was reduced by combinations of salt and sorbate. Nisin and lysozyme had insignificant effects on the probability of growth of Cl. sporogenes (P > 0.05). Lysozyme individually and in combination with nisin had no inhibitory effect on Cl. sporogenes. Overall, the addition of sorbate and lysozyme may allow the salt concentration to be reduced while preventing growth.     

Role of Bose enhancement in photoassociation

Abstract

We discuss the role of Bose enhancement of the dipole matrix element in photoassociation, using stimulated Raman adiabatic passage as an example. In a non-degenerate gas the time scale for coherent optical transients tends to infinity in the thermodynamic limit, whereas Bose enhancement keeps this time scale finite in a condensate. Coherent transients are therefore absent in photoassociation of a thermal non-degenerate gas, but are feasible if the gas is a condensate.     

Performative technologies for heritage site regeneration

Heritage sites are an important part of understanding our role in history. They have the potential to teach us important lessons, such as where we came from and subsequently, the people it has made us today. As members of a large, heritage-led, regeneration project, we are working with the Hafod–Morfa Copperworks, a heritage site in the Lower Swansea Valley where there is not much to see or hear. The few ruins at the site make it difficult to imagine what the site would have been like back in its heyday. Our goal at the site is to draw people together, not to view a finished piece of curated heritage, but rather, to start conversations about their memories and the significance of the site to them and to discover what they would like to see at the site in the future. The technology we are producing is about engaging with the local community and stakeholders as groups to provoke discussion. This contrasts with previous uses of mobile guides which only attempt to be tourist aids. In this article, we report on two prototype technologies we have developed to help accomplish this task. Throughout the article, we discuss how and why designing performative technologies could help encourage people to visit, socialise and communicate within the area. Our early results suggest that expressive performative technologies are good at gaining spectators’ attention and encouraging an active engagement between performer and spectator.     

A Practical and Controllable Hair and Fur Model for Production Path Tracing

We present an energy‐conserving fiber shading model for hair and fur that is efficient enough for path tracing. Our model adopts a near‐field formulation to avoid the expensive integral across the fiber, accounts for all high order internal reflection events with a single lobe, and proposes a novel, closed‐form distribution for azimuthal roughness based on the logistic distribution. Additionally, we derive, through simulation, a parameterization that relates intuitive user controls such as multiple‐scattering albedo and isotropic cylinder roughness to the underlying physical parameters.     

Very Low Degree of Energetic Disorder as the Origin of High Mobility in an n‐channel Polymer Semiconductor

Charge transport is investigated in high‐mobility n‐channel organic field‐effect transistors (OFETs) based on poly{[N,N′‐bis(2‐octyldodecyl)‐naphthalene‐1,4,5,8‐bis(dicarboximide)‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (P(NDI2OD‐T2), Polyera ActivInk? N2200) with variable‐temperature electrical measurements and charge‐modulation spectroscopy. Results indicate an unusually uniform energetic landscape of sites for charge‐carrier transport along the channel of the transistor as the main reason for the observed high‐electron mobility. Consistent with a lateral field‐independent transport at temperatures down to 10 K, the reorganization energy is proposed to play an important role in determining the activation energy for the mobility. Quantum chemical calculations, which show an efficient electronic coupling between adjacent units and a reorganization energy of a few hundred meV, are consistent with these findings.