Novel binary gene expression tools like the LexA-LexAop system could powerfully enhance studies of metabolism, development, and neurobiology in Drosophila. However, specific LexA drivers for neuroendocrine cells and many other developmentally relevant systems remain limited. In a unique high school biology course, we generated a LexA-based enhancer trap collection by transposon mobilization. The initial collection provides a source of novel LexA-based elements that permit targeted gene expression in the corpora cardiaca, cells central for metabolic homeostasis, and other neuroendocrine cell types. The collection further contains specific LexA drivers for stem cells and other enteric cells in the gut, and other developmentally relevant tissue types. We provide detailed analysis of nearly 100 new LexA lines, including molecular mapping of insertions, description of enhancer-driven reporter expression in larval tissues, and adult neuroendocrine cells, comparison with established enhancer trap collections and tissue specific RNAseq. Generation of this open-resource LexA collection facilitates neuroendocrine and developmental biology investigations, and shows how empowering secondary school science can achieve research and educational goals.

Over the past few decades, terahertz (THz) spectroscopy has become an established technique for studying the dielectric and transient photoconductive properties of materials. THz spectroscopy is a contact-free probe of electrical conductivity with subpicosecond time resolution, and it has proven especially useful for studying emerging materials. We highlight recent work used to study metal halide perovskites, metal oxides, metal–organic frameworks, and 2D materials in addition to providing an overview of methods in pump–probe THz spectroscopy. We focus on the ways in which THz spectroscopy can be used to study charge transport mechanisms and factors that might limit carrier mobility in emerging materials. This Perspective will provide a general understanding of pump–probe THz spectroscopy and how it can be applied to next-generation materials and will identify challenges and advantages in data processing to extract broadband complex conductivity spectra.

In the search for improved materials for photoelectrochemical water splitting, it has become important to identify new classes of semiconductor materials that may serve as improved photocathodes. To this end, p-type AgRhO2 has been synthesized and tested as a photocathode for water splitting. The AgRhO2 photocathode is found to exhibit excellent photocatalytic capability for reducing protons to H2 across a wide range of pH values with nearly 100% faradaic efficiency and good photostability. Polycrystalline AgRhO2 electrodes exhibit strong preferred c-axis orientation, resulting in anisotropic conductivity, evident from resistivity measurements. AgRhO2 photocathodes are found to provide improved performance and photostability when compared to prior work using a p-CuRhO2 electrode. Enhanced performance is in part attributed to the unusual degree of c-axis orientation found in this material. In addition, there is a significantly lower kinetic barrier for H2 production at the AgRhO2 interface.

One ongoing challenge in the field of iridium-based water oxidation catalysts is to develop a molecular precatalyst affording well-defined homogeneous active species for catalysis. Our previous work by using organometallic precatalysts Cp*Ir(pyalk)-OH and Ir(pyalk)(CO) 2 (pyalk = (2-pyridyl)-2-propanolate) suggested a μ-oxo-bridged Ir dimer as the probable resting state, although the structure of the active species remained elusive. During the activation, the ligands Cp* and CO were found to oxidatively degrade into acetic acid or other products, which coordinate to Ir centers and affect the catalytic reaction. Two related dimers bearing two pyalk ligands on each iridium were crystallized for structural analysis. However, preliminary results indicated that these crystallographically characterized dimers are not active catalysts. In this work, we accessed a mixture of dinuclear iridium species from a coordination precursor, Na[Ir(pyalk)Cl 4 ], and assayed their catalytic activity for oxygen evolution by using NaIO 4 as the oxidant. This catalyst showed comparable oxygen-evolution activity to the ones previously reported from organometallic precursors without demanding oxidative activation to remove sacrificial ligands. Future research along this direction is expected to provide insights and design principles toward a well-defined active species.

Terahertz (THz) spectroscopy is a powerful tool for unambiguously extracting complex-valued material properties (e.g., refractive index, conductivity, etc.) from a wide range of samples, with applications ranging from materials science to biology. However, extracting complex refractive indices from THz time-domain spectroscopy data can prove challenging, especially for multilayer samples. These challenges arise from the large number of transmission-reflection paths the THz pulse can take through the sample layers, leading to unwieldy strings of Fresnel coefficients. This issue has often been addressed using various approximations. However, these approximations are only applicable to specific classes of samples and can give erroneous results when misapplied. An alternative to this approach is to programmatically model all possible paths through the sample. The many paths through the sample layers can be modeled as a tree that branches at every point where the paths diverge, i.e., whenever the pulse can either be transmitted or reflected. This tree can then be used to generate expressions relating the unknown refractive index to the observed time domain data. Here, we provide a freely available open-source package implementing this method as both a MATLAB library and a corresponding graphical user interface, which can also be run without a MATLAB license (https://github.com/YaleTHz/nelly). We have tested this method for a range of samples and compared the results to commonly used approximations to demonstrate its accuracy and wide applicability. Our method consistently gives better agreement than common approximations.