Stacking Order Engineering of Two-Dimensional Materials and Device Applications.

Stacking orders in 2D van der Waals (vdW) materials dictate the relative sliding (lateral displacement) and twisting (rotation) between atomically thin layers. By altering the stacking order, many new ferroic, strongly correlated and topological orderings emerge with exotic electrical, optical and magnetic properties. Thanks to the weak vdW interlayer bonding, such highly flexible and energy-efficient stacking order engineering has transformed the design of quantum properties in 2D vdW materials, unleashing the potential for miniaturized high-performance device applications in electronics, spintronics, photonics, and surface chemistry. This Review provides a comprehensive overview of stacking order engineering in 2D vdW materials and their device applications, ranging from the typical fabrication and characterization methods to the novel physical properties and the emergent slidetronics and twistronics device prototyping. The main emphasis is on the critical role of stacking orders affecting the interlayer charge transfer, orbital coupling and flat band formation for the design of innovative materials with on-demand quantum properties and surface potentials. By demonstrating a correlation between the stacking configurations and device functionality, we highlight their implications for next-generation electronic, photonic and chemical energy conversion devices. We conclude with our perspective of this exciting field including challenges and opportunities for future stacking order engineering research.

Nanoscale covariance magnetometry with diamond quantum sensors.

Nitrogen vacancy (NV) centers in diamond are atom-scale defects that can be used to sense magnetic fields with high sensitivity and spatial resolution. Typically, the magnetic field is measured by averaging sequential measurements of single NV centers, or by spatial averaging over ensembles of many NV centers, which provides mean values that contain no nonlocal information about the relationship between two points separated in space or time. Here, we propose and implement a sensing modality whereby two or more NV centers are measured simultaneously, and we extract temporal and spatial correlations in their signals that would otherwise be inaccessible. We demonstrate measurements of correlated applied noise using spin-to-charge readout of two NV centers and implement a spectral reconstruction protocol for disentangling local and nonlocal noise sources.

Isolation of deoxyribonucleic acid and ribosomal ribonucleic acid from bacteria.

1. Nucleic acids were released from Escherichia coli by lysing with tri-iso-propylnaphthalene sulphonate and 4-aminosalicylate and then extracting with a phenol-cresol mixture. 2. Nucleic acids were similarly released from Bacillus subtilis after initial treatment with lysozyme. 3. DNA was sedimented after careful precipitation with m-cresol or 2-butoxyethanol (0.1-0.12vol.) in the presence of 20% sodium benzoate. 4. Contaminating ribosomal RNA was removed by precipitation in the presence of 4m-sodium chloride or by extracting DNA with an acetate-butyrate mixture, in which RNA is insoluble. 5. The DNA from B. subtilis has a transforming ability of 0.3-0.6% for the tryptophan marker. 6. Ribosomal RNA was then precipitated with rapidly labelled RNA by the addition of an equal volume of 2-butoxyethanol. 7. There was good separation of the nucleic acids from protein and polysaccharides.