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Abstract Controlling the number of molecular switches and their relative positioning within porous materials is critical to their functionality and properties. The proximity of many molecular switches to one another can hinder or completely suppress their response. Herein, a synthetic strategy involving mixed linkers is used to control the distribution of spiropyran-functionalized linkers in a covalent organic framework (COF). The COF contains a spiropyran in each pore which exhibits excellent reversible photoswitching behavior to its merocyanine form in the solid state in response to UV/Vis light. The spiro-COF possesses an urchin-shaped morphology and exhibits a morphological transition to 2D nanosheets and vesicles in solution upon UV light irradiation. The merocyanine-equipped COFs are extremely stable and possess a more ordered structure with enhanced photoluminescence. This approach to modulating structural isomerization in the solid state is used to develop inkless printing media, while the photomediated polarity change is used for water harvesting applications.

In this paper, we report the use of a superconducting transmon qubit in a 3D cavity for quantum machine learning and photon counting applications. We first describe the realization and characterization of a transmon qubit coupled to a 3D resonator, providing a detailed description of the simulation framework and of the experimental measurement of important parameters, such as the dispersive shift and the qubit anharmonicity. We then report on a Quantum Machine Learning application implemented on a single-qubit device to fit the u-quark parton distribution function of the proton. In the final section of the manuscript, we present a new microwave photon detection scheme based on two qubits coupled to the same 3D resonator. This could in principle decrease the dark count rate, favoring applications like axion dark matter searches.

The effect of precipitate coherency in an aged aluminum (Al) 2024 alloy is investigated using scanning transmission electron microscopy (STEM) and density functional theory (DFT) methods. The focus of the study is on understanding the effects of hydrogen (H2) entrapment in the alloy, which leads to the degradation of its corrosion resistance. We employed STEM to analyze the structure and strain properties of the alloy at high spatial resolution. This has been achieved by applying the geometrical phase analysis (GPA) to the acquired HRSTEM images. The determination of strain field around the precipitates was utilized to gauge the degree of coherency at the interface of the precipitates with Al matrix. We also applied density functional theory (DFT) simulations to investigate the interfacial energy at the interfaces of the precipitates with the Al matrix. The obtained results of the DFT simulations showed that the interfacial energy at the semi-coherent precipitates was determined to be 0.06 eV per atom, which was higher compared to the coherent precipitates. Our findings suggest that the semi-coherent precipitates have a less stable interface with the Al matrix. Furthermore, the study revealed that the H2 entrapped at the semi-coherent precipitate regions exhibits a binding energy which is 3.2 eV lower than that of the coherent precipitates. This implies that hydrogen binds more strongly at the semi-coherent precipitate cites, which enhances the process of the alloy embrittlement.

Two-dimensional (2D) surface-terminated layered transition metal carbide MXenes with high electrochemical performance paved the way for robust energy storage supercapacitor devices. However, because of the 2D nature of the MXene flakes, self-restacking of 2D MXene flakes limits the use of all the flake functionalized surfaces in MXene electrodes. Here, we report the synthesis of V2CTx MXene and multiwall carbon nanotube (MWCNT)/V2CTx composites as a promising electrode material for hybrid energy storage devices. Our hybrid electrodes exhibited enhanced electrochemical performance and a gravimetric capacitance of 1842 F g−1 at a scan rate of 2 mV s−1, with a specific charge capacity of 62.5 A h/g. Moreover, the electrodes presented an excellent rate performance, durability, and retention capacity of 94% lasted up to 10 000 cycles. Density functional theory calculations provided electronic and structural properties of the considered MWCNT@V2CTx. Therefore, the introduction of MWCNTs enhanced the conductivity and reaction kinetics of the MXenes and facilitates the charge storage mechanism useful for next-generation smart energy storage devices.

Hygroscopic materials which possess high moisture adsorption capacity were successfully upgraded by the functionalization of sodium chloride (NaCl) using two nuances of oxides. A procedure was developed to first prepare submicron-sized NaCl crystals; thereafter, these crystals were coated by choice of either titanium dioxide (TiO2) or silica (SiO2) to enhance the hygroscopic properties of NaCl and prevent its premature deliquescence. After coating, several analytical techniques were employed to evaluate the obtained composite materials. Our findings revealed that both composites NaCl-TiO2 and NaCl-SiO2 gave excellent performances by exhibiting interesting hydrophilic properties, compared to the sole NaCl. This was demonstrated by both environmental scanning electron microscope (ESEM) and water vapor adsorption experiments. In particular, NaCl-TiO2 composite showed the highest water adsorption capacity at low relative humidity and at a faster adsorption rate, induced by the high surface energy owing to the presence of TiO2. This result was also confirmed by the kinetics of adsorption, which revealed that not only does NaCl-TiO2 adsorb more water vapor than NaCl-SiO2 or sole NaCl but also the adsorption occurred at a much higher rate. While at room temperature and high relative humidity, the NaCl-SiO2 composite showed the best adsorption properties making it ideal to be used as a hygroscopic material, showing maximum adsorption performance compared to NaCl-TiO2 or sole NaCl. Therefore, NaCl-TiO2 and NaCl-SiO2 composites could be considered as promising hygroscopic materials and potential candidates to replace the existing salt seeding agents.

To achieve low contact resistance between metal and III-V material, transmission-line-model (TLM) structures of molybdenum (Mo) were fabricated on indium phosphide (InP) substrate on the top of an indium gallium arsenide (InGaAs) layer grown by molecular beam epitaxy. The contact layer was prepared using a digital etch procedure before metal deposition. The contact resistivity was found to decrease significantly with the cleaning process. High Resolution Transmission & Scanning Electron Microscopy (HRTEM & HRSTEM) investigations revealed that the surface roughness of treated samples was increased. Further analysis of the metal-semiconductor interface using Energy Electron Loss Spectroscopy (EELS) showed that the amount of oxides (InxOy, GaxOy or AsxOy) was significantly decreased for the etched samples. These results suggest that the low contact resistance obtained after digital etching is attributed to the combined effects of the induced surface roughness and oxides removal during the digital etch process.