Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

Nutrition during pregnancy can induce alterations in offspring phenotype. Maternal ratio of protein to non-protein (P:NP) energy has been linked to variations in offspring body composition and adult risk of metabolic disease. This study describes the dietary patterns of pregnant women by tertiles of the P:NP ratio and compares diet to Australian recommendations. Data are from 179 Australian women enrolled in the Women and Their Children’s Health Study. Diet was assessed using a validated 74-item food frequency questionnaire. Food group servings and nutrient intakes were compared to the Australian Guide to Healthy Eating and Australian Nutrient Reference Values. Higher maternal P:NP tertile was positively associated with calcium (P = 0.003), zinc (P = 0.001) and servings of dairy (P = 0.001) and meat (P = 0.001) food groups, and inversely associated with the energy dense, nutrient poor non-core (P = 0.003) food group. Micronutrient intakes were optimized with intermediate protein (18%E–20%E), intermediate fat (28%E–30%E) and intermediate carbohydrate (50%E–54%E) intakes, as indicated in tertile two. Results suggest a moderate protein intake may support pregnant women to consume the largest variety of nutrients across all food groups.

The field electron emission performance of bulk, 1D, and 2D nanomaterials is here empirically compared in the largest metal‐analysis of its type. No clear trends are noted between the turn‐on electric field and maximum current density as a function of emitter work function, while a more pronounced correlation with the emitters dimensionality is noted. The turn‐on field is found to be twice as large for bulk materials compared to 1D and 2D materials, empirically confirming the wider communities view that high aspect ratios, and highly perturbed surface morphologies allow for enhanced field electron emitters.