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Plasmonic rulers (PRs) linking nanoscale distance dependence spectral shifts are important for studying cellular microenvironments and biomarker detection. The traditional PR design employs tethering metal nanoparticle pairs using synthetic and biopolymers that severely suffer from reproducibility issues, as well as lack reversibility. Here, the fabrication of novel PRs is reported through the formation of self‐assembled monolayers (SAMs) of photoswitchable molecular machines chemically tethered onto sharp‐tip gold nanostructures (Au NSs). This unique and highly sensitive PR utilizes localized surface plasmon resonance (LSPR) properties of Au NSs to spectroscopically evaluate dipole–dipole coupling between NSs and photoisomerizable spiropyran (SP)‐merocyanine (MC) conjugates in the solid‐state. It is observed that the SAM‐modified NSs are extremely sensitive to the photoisomerization of SP‐to‐MC, resulting in LSPR shifts as large as 5.6 nm for every 1.0 Å change in distance. The highly dipolar MC changes the NS‐SAM interfacial polarizability and alters the dipole–dipole coupling leading to the ultrasensitive PR is hypothesized. The hypothesis is supported theoretically by calculating dipole polarizability of an inorganic‐organic heterodimer model and experimentally by determining work function and interfacial dipole values. Taken together, this work represents the fabrication of next‐generation PRs, which hold great promise for advanced, plasmonic‐based sensors and optoelectronic device fabrication.

We study theqKZdifference equations with values in the th tensor power of the vector representation , variables , and integer step . For any integer relatively prime to the step , we construct a family of polynomials in variables with values in such that the coordinates of these polynomials with respect to the standard basis of are polynomials with integer coefficients. We show that satisfy theqKZequations modulo . Polynomials are modulo analogs of the hypergeometric solutions of theqKZgiven in the form of multidimensional Barnes integrals.

Ion mobility spectrometry coupled to mass spectrometry (IMS/MS) is a widely used tool for biomolecular separations and structural elucidation. The application of IMS/MS has resulted in exciting developments in structural proteomics and genomics. This perspective gives a brief background of the field, addresses some of the important issues in making structural measurements, and introduces complementary techniques.

The merging of photocatalysis with halogen‐atom transfer (XAT) processes has proven to be a versatile tool for the generation of carbon‐centered radicals in organic synthesis. XAT processes are unique in that they generate radicals without requiring the use of strong reductants necessary for the traditional single electron transfer (SET) activation of halides. Pathways to achieve XAT in synthetic applications can be categorized into three major sections: i) heteroatom‐based activators, ii) metal‐based activators, and iii) carbon‐based activators among which α‐aminoalkyl radicals have taken the center stage. Access to these α‐aminoalkyl radicals as XAT reagents has gained significant attention in the past few years due to the robustness of the reactions, the simplicity of the reagents required, and the broadness of their applications. Generation of these α‐aminoalkyl radicals is simply achieved through the single electron oxidation of tertiary amines, which after deprotonation at the α‐position generates the α‐aminoalkyl radicals. Due to the wide scope of tertiary amines available and the tunable nucleophilicity of α‐aminoalkyl radical formed, this strategy has become an attractive alternative to heteroatom/metal‐based radicals for XAT. In this minireview, we focus our attention on recent (2020–2023) developments and uses of this robust technology to mediate XAT processes.

To advance the MXene field, it is crucial to optimize each step of the synthesis process and create a detailed, systematic guide for synthesizing high‐quality MXene that can be consistently reproduced. In this study, a detailed guide is provided for an optimized synthesis of titanium carbide (Ti₃C₂T_x) MXene using a mixture of hydrofluoric and hydrochloric acids for the selective etching of the stoichimetric‐Ti₃AlC₂MAX phase and delamination of the etched multilayered Ti₃C₂T_xMXene using lithium chloride at 65 °C for 1 h with argon bubbling. The effect of different synthesis variables is investigated, including the stoichiometry of the mixed powders to synthesize Ti₃AlC₂, pre‐etch impurity removal conditions, selective etching, storage, and drying of MXene multilayer powder, and the subsequent delamination conditions. The synthesis yield and the MXene film electrical conductivity are used as the two parameters to evaluate the MXene quality. Also the MXenes are characterized with scanning electron microscopy, x‐ray diffraction, atomic force microscopy, and ellipsometry. The Ti₃C₂T_xfilm made via the optimized method shows electrical conductivity as high as ≈21,000 S/cm with a synthesis yield of up to 38 %. A detailed protocol is also provided for the Ti₃C₂T_xMXene synthesis as the supporting information for this study.

Classifying insect species involves a tedious process of identifying distinctive morphological insect characters by taxonomic experts. Machine learning can harness the power of computers to potentially create an accurate and efficient method for performing this task at scale, given that its analytical processing can be more sensitive to subtle physical differences in insects, which experts may not perceive. However, existing machine learning methods are designed to only classify insect samples into described species, thus failing to identify samples from undescribed species.

Most fog detection from space cannot differentiate fog and low stratus clouds, and cannot estimate fog deposition. This study assessed the feasibility of using spaceborne lidar observations from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) in fog detection and estimation. We tested the method in the central Namib Desert, Namibia, where frequent fog events occur and fog observations are available. Results showed the CALIPSO backscatter signal at 532 nm can differentiate low clouds and fog due to its high‐resolution vertical profiles. Backscatter signals during fog events were significantly higher than those during non‐fog periods. TheR²between backscatter signals and fog observations was 0.85. Moreover, the backscatter signal was also sensitive to relative humidity variation (R² = 0.66). These results indicate that the CALIPSO data are feasible to estimate fog occurrence and deposition, providing a new perspective for space‐based fog studies.

We use the Riemann–Hilbert approach, together with string and Toda equations, to study the topological expansion in the quartic random matrix model. The coefficients of the topological expansion are generating functions for the numbers of 4‐valent connected graphs withjvertices on a compact Riemann surface of genusg. We explicitly evaluate these numbers for Riemann surfaces of genus 0,1,2, and 3. Also, for a Riemann surface of an arbitrary genusg, we calculate the leading term in the asymptotics of as the number of vertices tends to infinity. Using the theory of quadratic differentials, we characterize the critical contours in the complex parameter plane where phase transitions in the quartic model take place, thereby proving a result of David. These phase transitions are of the following four types: (a) one‐cut to two‐cut through the splitting of the cut at the origin, (b) two‐cut to three‐cut through the birth of a new cut at the origin, (c) one‐cut to three‐cut through the splitting of the cut at two symmetric points, and (d) one‐cut to three‐cut through the birth of two symmetric cuts.