In order to reach the full civic and scientific potential of physics, this white paper calls for a culture change in physics to recognize informal physics education (also referred to as public engagement or outreach) as an essential disciplinary practice. That is, engaging in informal physics education (IPE) is part of what it means to ”do physics.” In June 2024, we hosted a summit with forty-two members of the Joint Network for Informal Physics Education and Research (JNIPER) to discuss concrete steps for fostering this cultural shift in physics. We present key findings from the Summit to motivate this culture change: IPE makes the work of physicists relevant; fosters trust and supports a society where everyone benefits from science and technology advances; serves as a gateway for entering into the physics discipline, and for staying once there; and improves physicists' skills and research. We identify three levers for promoting the culture change: structures supporting IPE; engagement of interested, influential, and/or impacted parties; and integration of research-based IPE practices. Each lever is accompanied by associated recommendations for action directed at individuals, departments and institutions, topical groups such as JNIPER, and funders and (inter)national organizations. Our clarion call is for members and supporters of the IPE community to choose one recommendation per lever to prioritize and to set forth a roadmap for implementation. Together, we can establish IPE as a central physics practice, ultimately leading to a deeper connection between physics and society, strengthening our mutual potential and impact for good.

We explore in this paper the impulse to share our academic work via social media as well as the impact this sharing has on our senses of self as scholars and persons. We argue that this sharing raises a number of important philosophical questions: In what way does the branding or profiling encouraged by X/Twitter impact on our personal identity? How does the publicness of this particular platform disrupt the intimacy that lies at the heart of all edifying human relationship? And to invoke the terms of critical theorist, Axel Honneth, can we as teachers and researchers recognize ourselves in the social media sphere? Writing from the perspective of philosophy of education, Conroy and Smith (2017: 706) have argued that the contemporary university has been taken over by ‘Professor Lookatme’ and ‘Dr Loudmouth’ – but we are interested in the extent to which these caricatured figures are necessarily representative of today’s academy. While our paper draws attention to the dark side of social media, then, it still explores the possibilities for authentic selfhood as well as meaningful community in our increasingly digitized academic worlds.

This paper examines the representation of women in Irish Leaving Certificate Physics textbooks. Findings show that women are significantly underrepresented, both in terms of scientific characters (historic and current) described within the textbooks, and also in terms of more general non-scientific characters within the books. Furthermore, analysis suggests that the language used to describe characters mentioned in the books may compound gender inequalities. Relevant policies (curricular, governmental, etc) are examined and suggestions are made to improve gender balance in future textbooks.

Many undergraduate and graduate physics students participate in some form of public engagement throughout the course of their studies, often through groups supported by physics departments and universities. These informal teaching and learning programs can offer unique opportunities for physics identity development. Understanding how physics identities can be fostered will allow us to work toward a field that is inclusive of more identities. In this study, we build on previous work to investigate student-facilitator experiences in three informal physics programs using an operationalized Communities of Practice framework. Through our analysis, we identify different structures within these programs that support physics identity development.

Informal learning offers opportunities for physics - opportunities that I hope the physics education research (PER) community can co-define and engage with. This commentary piece is a personal reflection on this topic. It reflects, and builds on, my Physics Education Research Conference (PERC) 2019 presentation. Grounded in my personal experiences with informal physics education, my PERC presentation asked those present to collectively consider the values, practices, and people they associate with successful informal learning. Attendee comments are presented and discussed in ways that I hope the PER community will identify with and respond to. They suggest myriad opportunities that informal learning offers physics - opportunity to i) engage diverse groups of people in doing physics; ii) for physicists as a community; iii) to advance the field.

This study examines the potential of problem-based cooperative learning (PBCL) in expanding undergraduate physics students' understanding of, and engagement with, the scientific process. Two groups of first-year physics students (n=180) completed a questionnaire which compared their perceptions of learning science with their engagement in physics labs. One cohort completed a lab based on a PBCL approach, whilst the other completed the same experiment, using a more traditional, manual-based lab. Utilising a participant research approach, the questionnaire was co-constructed by researchers and student advisers from each cohort in order to improve shared meaning between researchers and participants. Analysis of students' responses suggests that students in the PBCL cohort engaged more in higher-order problem-solving skills and evidenced a deeper understanding of the scientific process than students in the more traditional, manual-based cohort. However, the latter cohort responses placed more emphasis on accuracy and measurement in lab science than the PBCL cohort. The students in the PBCL cohort were also more positively engaged with their learning than their counterparts in the manual led group.

The surface energy of graphene nanosheets is surprisingly poorly known, probably due to size effects and energetic heterogeneities. Here we use finite-dilution inverse gas chromatography to measure the surface energy of liquid-exfoliated, few-layer graphene nanosheets of different sizes as a function of probe coverage. In all cases, the surface energy falls with probe coverage from a defect-controlled, lowcoverage value to a value that approaches the basal plane surface energy at high coverage. Wefind an intrinsic basal plane dispersive surface energy of 61 +/- 4mJ m(-2), close to the value of 63 mJ m(-2) found for graphite. By comparison with similar data measured on graphite and using simple models, we can use the length dependence of the low coverage surface energy to differentiate between the effects of edge and basal plane defects, finding these to contribute similar to 130 and 180 mJ m(-2) to the surface energy respectively. From this data, we estimate a basal plane defect content of similar to 6 x 10(14) defectsm -2 for both graphite and graphene in reasonable agreement with Raman data. This work shows that, in terms of surface energetics, few-layer graphene nanosheets behave exactly like graphite with the only differences associated with platelet dimensions.

The constituent nanofibrils of bacterial cellulose are of interest to many researchers because of their purity and excellent mechanical properties. Mechanisms to disrupt the network structure of bacterial cellulose (BC) to isolate bacterial cellulose nanofibrils (BCN) are limited. This work focuses on liquid-phase dispersions of BCN in a range of organic solvents. It builds on work to disperse similarly intractable nanomaterials, such as single-walled carbon nanotubes, where optimum dispersion is seen for solvents whose surface energies are close to the surface energy of the nanomaterial; bacterial cellulose is shown to disperse in a similar fashion. Inverse gas chromatography was used to determine the surface energy of bacterial cellulose, under relevant conditions, by quantifying the surface heterogeneity of the material as a function of coverage. Films of pure BCN were prepared from dispersions in a range of solvents; the extent of BCN exfoliation is shown to have a strong effect on the mechanical properties of BC films and to fit models based on the volumetric density of nanofibril junctions. Such control offers new routes to producing robust cellulose films of bacterial cellulose nanofibrils.

Historically, reported values for the surface energy of graphite have covered a very wide range. Here, we use finite-dilution inverse gas chromatography (FD-IGC) to show that the dispersive component of the surface energy of graphite has contributions from edge and basal plane defects as well as from the hexagonal carbon lattice. The surface energy associated with the defect-free hexagonal lattice is measured at high probe-coverage to be 63 +/- 7 mJ/m(2), independent of graphite type. However, the surface energy measured at low probe coverage varied from 125 to 175 mJ/m(2) depending on the graphite type. Simulation of the FD-IGC output for different binding site distributions allows us to associate this low-coverage surface energy with the binding of probe molecules to high energy defect sites. Importantly, we find the rate of decay of surface energy with probe coverage to carry information about the defect density. By analyzing the dependence of these properties on flake size, it is possible to separate out the contributions of edge and basal plane defects, estimating the basal plane defect content to be similar to 10(15) m(-2) for all graphite samples. Comparison with simulation gives some insights into the basal plane and defect binding energy distributions.

When physicists at Trinity College Dublin began looking after an antique funnel full of pitch, they had no idea their humble experiment would spawn one of 2013's most "viral" news stories. Shane D Bergin, Stefan Hutzler and Denis Weaire reflect on the value of "slow science" to a hyper-connected, social-media world.

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Despite voluminous research on the acid oxidation of carbon nanotubes (CNTs), there is a distinct lack of experimental results showing distributions of functional groups at the nanometre length scale. Here, functional peaks have been mapped across individual multi-walled CNTs with low-dose, monochromated electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Density functional theory simulations show that the EELS features are consistent with oxygenated functional groups, most likely carboxyl moieties.

We report a simple model describing the solubility of rods in solvents, expressing the final result explicitly in terms of the surface entropy and the enthalpy of mixing. This model can be combined with any expression for the mixing enthalpy depending on the requirements. For example, in one instance it predicts the dispersed concentration of rods to decrease exponentially with the Flory-Huggins parameter of the dispersion. Using a different enthalpy function, it predicts a Gaussian peak when concentration is plotted versus solvent surface energy. The model also suggests specific solvent-rod interactions to be important and shows the dispersed concentration to be very sensitive to ordering at the solvent-rod interface. We have used this model to describe experimental results for the concentration of dispersed nanotubes in various solvents. Qualitative agreement with these predictions is observed experimentally. However, we suggest that the fact that quantitative agreement is not found may be explained by solvent ordering at the nanotube surface.

The aggregation of misfolded proteins is a common feature underlying a wide range of age-related degenerative disorders, including Alzheimer's and Parkinson's diseases. A key aspect of understanding the molecular origins of these conditions is to define the manner in which specific types of protein aggregates influence disease pathogenesis through their interactions with cells. We demonstrate how selenium-enhanced electron microscopy (SE-EM), combined with tomographic reconstruction methods, can be used to image, here at a resolution of 5-10 nm, the interaction with human macrophage cells of amyloid aggregates formed from Aβ(25-36), a fragment of the Aβ peptide whose self-assembly is associated with Alzheimer's disease. We find that prefibrillar aggregates and mature fibrils are distributed into distinct subcellular compartments and undergo varying degrees of morphological change over time, observations that shed new light on the origins of their differential toxicity and the mechanisms of their clearance. In addition, the results show that SE-EM provides a powerful and potentially widely applicable means to define the nature and location of protein assemblies in situ and to provide detailed and specific information about their partitioning and processing.

We have studied the dispersion and exfoliation of four inorganic layered compounds, WS(2), MoS(2), MoSe(2), and MoTe(2), in a range of organic solvents. The aim was to explore the relationship between the chemical structure of the exfoliated nanosheets and their dispersibility. Sonication of the layered compounds in solvents generally gave few-layer nanosheets with lateral dimensions of a few hundred nanometers. However, the dispersed concentration varied greatly from solvent to solvent. For all four materials, the concentration peaked for solvents with surface energy close to 70 mJ/m(2), implying that all four have surface energy close to this value. Inverse gas chromatography measurements showed MoS(2) and MoSe(2) to have surface energies of ∼75 mJ/m(2), in good agreement with dispersibility measurements. However, this method suggested MoTe(2) to have a considerably larger surface energy (∼120 mJ/m(2)). While surface-energy-based solubility parameters are perhaps more intuitive for two-dimensional materials, Hansen solubility parameters are probably more useful. Our analysis shows the dispersed concentration of all four layered materials to show well-defined peaks when plotted as a function of Hansen's dispersive, polar, and H-bonding solubility parameters. This suggests that we can associate Hansen solubility parameters of δ(D) ∼ 18 MPa(1/2), δ(P) ∼ 8.5 MPa(1/2), and δ(H) ∼ 7 MPa(1/2) with all four types of layered material. Knowledge of these properties allows the estimation of the Flory-Huggins parameter, χ, for each combination of nanosheet and solvent. We found that the dispersed concentration of each material falls exponentially with χ as predicted by solution thermodynamics. This work shows that solution thermodynamics and specifically solubility parameter analysis can be used as a framework to understand the dispersion of two-dimensional materials. Finally, we note that in good solvents, such as cyclohexylpyrrolidone, the dispersions are temporally stable with >90% of material remaining dispersed after 100 h.

Demand for carbon nanotubes (CNTs) is increasing rapidly in electrical, mechanical, and health and medical applications due to their thermal, electrical conductive and other properties. The continued commercial up-scaling of CNT production and application needs to be accompanied by an understanding of the occupational health, public safety and environmental implications of these materials. An increasing volume of literature on the toxicity of CNTs is being published; however, the results of these studies are frequently inconclusive. Due to the enormous number of permutations of nanoparticle shape, dimensions, composition and surface chemistry, only a fundamental understanding of the processes by which CNTs interact with cells will allow a realistic, practical assessment of the risks of the wide range of possible products. Alternatively, by understanding how the physicochemical properties of CNTs relate to their interaction with cells, it will be possible to design 'medical grade' CNTs, which can be used as diagnostic agents or as vectors to deliver therapeutic agents to cell and tissue targets. This article discusses the challenges associated with characterizing the toxicity of CNTs and the need for complimentary nanometrology techniques to relate their physicochemical properties to their toxicity.

If they could be easily exfoliated, layered materials would become a diverse source of two-dimensional crystals whose properties would be useful in applications ranging from electronics to energy storage. We show that layered compounds such as MoS(2), WS(2), MoSe(2), MoTe(2), TaSe(2), NbSe(2), NiTe(2), BN, and Bi(2)Te(3) can be efficiently dispersed in common solvents and can be deposited as individual flakes or formed into films. Electron microscopy strongly suggests that the material is exfoliated into individual layers. By blending this material with suspensions of other nanomaterials or polymer solutions, we can prepare hybrid dispersions or composites, which can be cast into films. We show that WS(2) and MoS(2) effectively reinforce polymers, whereas WS(2)/carbon nanotube hybrid films have high conductivity, leading to promising thermoelectric properties.