Tuneable separation of gold by selective precipitation using a simple and recyclable diamide

The efficient separation of metals from ores and secondary sources such as electronic waste is necessary to realising circularity in metal supply. Precipitation processes are increasingly popular and are reliant on designing and understanding chemical recognition to achieve selectivity. Here we show that a simple tertiary diamide precipitates gold selectively from aqueous acidic solutions, including from aqua regia solutions of electronic waste. The X-ray crystal structure of the precipitate displays an infinite chain of diamide cations interleaved with tetrachloridoaurate. Gold is released from the precipitate on contact with water, enabling ligand recycling. The diamide is highly selective, with its addition to 29 metals in 2 M HCl resulting in 70% gold uptake and minimal removal of other metals. At 6 M HCl, complete collection of gold, iron, tin, and platinum occurs, demonstrating that adaptable selective metal precipitation is controlled by just one variable. This discovery could be exploited in metal refining and recycling processes due to its tuneable selectivity under different leaching conditions, the avoidance of organic solvents inherent to biphasic extraction, and the straightforward recycling of the precipitant.

The structural basis of odorant recognition in insect olfactory receptors

Olfactory systems must detect and discriminate an enormous diversity of chemicals in the environment. To contend with this challenge, diverse species have converged on a common strategy in which odorant identity is encoded through the combinatorial activation of large families of olfactory receptors (ORs), thus allowing a finite number of receptors to detect an almost infinite chemical world. Although most individual ORs are sensitive to a variety of odorants, the structural basis for such flexible chemical recognition remains unknown. Here, we combine cryo-electron microscopy with functional studies of receptor tuning to gain insight into the structural and mechanistic basis of promiscuous odorant recognition. We show that OR5 from the jumping bristletail, Machilis hrabei, assembles as a homo-tetrameric odorant-gated ion channel with broad chemical tuning. We elucidated the structure of OR5 in multiple gating states, alone and in complex with two of its agonists—the odorant eugenol and the insect repellent DEET. Both ligands bind to a common binding site located in the transmembrane region of each subunit, composed of a simple geometric arrangement of aromatic and hydrophobic residues. We reveal that binding is mediated by hydrophobic, non-directional interactions with residues distributed throughout the binding pocket, enabling the flexible recognition of structurally distinct odorants. Mutation of individual residues lining the binding pocket predictably altered OR5’s sensitivity to eugenol and DEET and broadly reconfigured the receptor’s tuning, supporting a model in which diverse odorants share the same structural determinants for binding. Together, these studies provide structural insight into odorant detection, shedding light onto the molecular recognition mechanisms that ultimately endow the olfactory system with its immense discriminatory capacity.

Sensor behavior of MoS2 field-effect transistor with light injection toward chemical recognition

The application of field-effect transistor (FET) devices with atomically thin channels as sensors has attracted significant attention. We further explore the method to attach the chemical recognition capability by combining with light injection.

A kinetic model of thin-film fluorescent sensors for strategies to enhance chemical selectivity

An analytical model was developed for thin film chemical sensors which provides insight into the sensor dynamics and potential strategies to develop chemical recognition.

Quantification Analysis of 13 Organic Components and 8 Inorganic Elements in Angelica Sinensis Radix and Its Different Parts Combined with Chemical Recognition Pattern

Angelica Sinensis Radix (Danggui, DG) is one of the most commonly prescribed traditional Chinese medicines. The organic components include phthalides and phenolic acids. Meanwhile, inorganic elements play an important role in clinical effect. DG and its different parts have different effects. There is no relevant report on the analysis of organic compounds and inorganic elements among them. Therefore, ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry was developed for the simultaneous determination of 13 organic components (8 phthalides and 5 phenolic acids), and 8 inorganic elements were determined by inductively coupled plasma mass spectrometry. The contents of 32 samples were analyzed by orthogonal partial least squares discrimination analysis, hierarchical cluster analysis, and least-significant difference of one-way analysis of variance. The results showed that the differences were significant among DG and its different parts. 11 difference markers (Ca, Z-ligustilide, Mg, Mn, Fe, Na, K, Cu, Zn, coniferyl ferulate, and senkyunolide A) were obtained by variable importance for the project. These difference markers were some different among DG and its different parts, especially Z‐ligustilide, coniferyl ferulate, Mg, Zn, the differences were significant. This study can provide a reference for DG research.

Chemical blindness in Liolaemus lizards is counterbalanced by visual signals, the case of two species with different communication modalities

Animals employ a wide variety of communication tactics that rely on distinct sensory modalities. Lizards are characterized by their heightened dependence on chemical and visual communication. Some authors have proposed that a reduced number of chemical secretory pores may be associated with an increased visual dependence in some species. Here, we study two species of Liolaemus lizards with different chemical features to compare their visual and chemical communication. The first species, L. coeruleus, does not have precloacal pores in either sex, while L. albiceps has precloacal pores in both sexes. We expect that L. coeruleus will principally adhere to the visual modality, while L. albiceps will show greater chemical responses. We filmed the lizard’s response to different chemical and visual stimuli. In the trials, both species demonstrated chemical self-recognition, L. albiceps exhibited less total time in motion but more behavioural displays in the presence of conspecific scents, suggesting conspecific chemical recognition too. On the other hand, visuals results showed that L. coeruleus reacted more to the presence of conspecifics than L. albiceps. These observations suggest that L. coeruleus relies more on visual signalization, while L. albiceps has a greater dependence on chemical communication. Our results may indicate a correspondence between precloacal secretions and the response to these by conspecifics in both species studied.