The combination of molecular recognition [1] and selfassembly processes [2] offers a powerful route to the development of nanoscale systems that have technological applications as sensors, devices, and switches. [3] Macrocyclic ligands continue to attract widespread attention, [4] especially when complexation of a neutral or ionic guest at one site in the molecule induces a change in the optical [5] or redox properties [6] of the system.The recent incorporation of the electroactive tetrathiafulvalene (TTF) unit into metal-binding macrocyclic structures has demonstrated that they can function as metal-cation sensors in organic media. [7] The presence of a metal cation imposes an inductive effect on the polarizable TTF system, resulting in an anodic shift of the first oxidation potential as indicated by cyclic voltammetry experiments (e.g., for compound 1, a maximum shift of DE 1,1/2 = 80 mV for Na + complexation has been observed); [7] the second oxidation potential is essentially unchanged, consistent with the expulsion of the metal cation after the first oxidation. There is current interest in electrochemically active self-assembled monolayers (SAMs), [8] and the recent observation of stable redox chemistry of TTF derivatives 2 in self-assembled monolayers [8b] prompted us to investigate thin-film electrochemical sensors based on the cation-sensitive redox-active molecules 6 and 9 immobilized on a metal surface. SAMs represent an attractive method for device fabrication, having the advantages of straightforward preparation and being generally very robust (stable to solvents, acids, and bases). The key starting reagent in our syntheses of compounds 6 and 9 (Scheme 1) is compound 3, [9] the hydrolysis of which under basic conditions (1 M sodium hydroxide in dioxane) yielded, after acidic work-up, the acid derivative 4 (75 % yield). Treatment of acid 4 with either 12-bromo-1-dodecanol or 6-bromo-1-hexanol in the presence of dicyclohexylcarbodiimide (DCC) and N,N-dimethylaminopyridine (DMAP) afforded ester derivatives 5a and 5b, respectively (75 and 85 % yield, respectively) with subsequent conversion of the bromide into a thiol being achieved by treatment with thiourea followed by basic hydrolysis of the intermediate isothiouronium salt to afford the target derivatives 6a and 6b (42 and 33 % yield, respectively). In both cases, this last step gave a complex reaction mixture; consequently, the purified yields for compounds 6a and 6b were reduced as a result of repeated chromatography. The byproducts could not be obtained pure and their structures are unknown. Reduction of compound 3 to afford the methanol derivative 7 occurred in dichloromethane at ±78 C using diisobutylaluminum hydride (DIBAL-H) [10] (85 % yield). Using a modification [11] of the Mitsunobu reaction [12] we successfully converted alcohol 7 into sulfanylmethyl derivative 9:[13] a mixture of compound 7 and thioacetic acid in tetrahydrofuran was added to a stirred mixture of diisopropyl azodicarboxylate (DIAD) and triphenylphosphine in tetrahydrofur...

Humans in hazardous environments take actions to reduce unnecessary risk, including limiting exposure to radioactive materials where ionising radiation can be a threat to human health. Robots can adopt the same approach of risk avoidance to minimise exposure to radiation, therefore limiting damage to electronics and materials. Reducing a robot’s exposure to radiation results in longer operational lifetime and better return on investment for nuclear sector stakeholders. This work achieves radiation avoidance through the use of layered costmaps, to inform path planning algorithms of this additional risk. Interpolation of radiation observations into the configuration space of the robot is accomplished using an inverse distance weighting approach. This technique was successfully demonstrated using an unmanned ground vehicle running the Robot Operating System equipped with compatible gamma radiation sensors, both in simulation and in real-world mock inspection missions, where the vehicle was exposed to radioactive materials in Lancaster University’s Neutron Laboratory. The addition of radiation avoidance functionality was shown to reduce total accumulated dose to background levels in real-world deployment and up to a factor of 10 in simulation.

When disasters and crises arise visual information needs to be rapidly gathered and assessed in order to assist rescue workers and emergency personnel. Often such situations are life-threatening and people cannot safely obtain such information. Disasters in urban areas are particularly taxing. Structural collapse, damaged staircases and the loss communication infrastructures aggravate rescue efforts. Robots, equipped with camera, can be employed to visually capture situational awareness. As such, the focus of our work is designing a backpackable aerial robot that can hoverand-stare. Such a robot would ascend, peer through windows, and transmits video to an operator. This paper presents a backpackable tandem-rotor prototype that can carry a wireless camera.

In this research, a combined fast-neutron/γ-raybackscatter imaging technique is described. The aim of this work is to understand corrosion defects in pipelines by measuring differences in the scattered radiation flux, generated when different steel thicknesses are irradiated by a neutron and γ-ray focused beam. A californium-252 radiation source is used to produce fast neutron and γ rays, exploiting its spontaneousfission. This mixed radiation field is collimated and directed towards the steel samples. Backscattered neutrons and γ rays aremeasured as a function of the steel thickness using 4 liquid organic scintillation detectors linked to a real-time, pulse-shape discrimination system, which separates and retains the neutron and γ-ray event data. In this paper, we describe how, using asingle radiation source and detection system, it is possible to perform and combine two complementary imaging modalities. This research is validated by an MCNP6 computer simulation study. The backscatter imaging system developed for this research and the experimental results of the measurements carried out using the National Physical Laboratory neutron low-scatter facility are also presented in this paper.

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