Israel Journal of Chemistry最新文献

The cover image shows the logo of the 15th International Conference on Quasicrystals, held at Tel Aviv University in June 2023. The logo depicts the hexagonal Star of David. The background depicts a hexagonal quasiperiodic tiling, whose construction and characterization are the focus of the Review by Coates et al. in this volume. Such aperiodic yet perfectly ordered trigonal and hexagonal tilings served to study various experimental systems, such as the 3-fold surfaces of icosahedral quasicrystals and 6-fold bilayer graphene.

We provide an overview on the theory of topological quantum numbers from the point of view of non-commutative topology. Topological phases are described by K-groups of C*-algebras. The algebras are constructed from the set of positions of the nuclei of the materials we want to study. Topological quantum numbers are Chern numbers of K-group elements. Maps between K-groups which are of algebraic topological origin provide the means to obtain relations between different topological quantum numbers as, for instance, in the bulk edge correspondence. We present simple aperiodic examples related to quasicrystals to illustrate the theory.

The study of quasicrystals – materials that are characterized by their aperiodic yet long-range ordered structures^1-5 – continues to evolve, offering new challenges and opportunities in understanding complex-ordered systems that transcend traditional crystallography. They have emerged as a rich interdisciplinary field, encompassing mathematics, physics, chemistry, and materials science. This introduces the additional challenge of bridging varied research communities, each with its distinct language and culture. Central to the investigation of quasicrystals are mathematical tools that describe their intricate geometric and topological properties, physical models that capture their unique electronic and other physical properties, as well as innovative experimental methods that can be employed to analyze their unique and complex nature. This special issue of the Israel Journal of Chemistry is dedicated to the latest advancements in quasicrystal research, presented at ICQ15 – the 15th International Conference on Quasicrystals – held on the campus of Tel Aviv University in June 2023 (see Fig. 1 for a group photo). It offers a valuable snapshot of the current state of quasicrystal research, highlighting the progress made in recent years and the challenges that lie ahead. The collection of Reviews and Research Articles, included here, spans a broad spectrum of topics, reflecting the diverse and interdisciplinary nature of quasicrystal research, providing a good entry point, as well as some deep insight, into the theoretical, experimental and practical underpinnings of aperiodic long-range order.

Liquid phase TEM has attracted widespread attention in recent years as a groundbreaking tool to address various fundamental problems in nanoscience. It has provided the opportunity to reveal many unseen dynamic phenomena of nanoscale materials in solution processes by direct imaging through liquids with high spatial and temporal resolution. After my earlier work on real-time imaging of the nucleation, growth, and dynamic motion of nanoparticles in liquids by developing high-resolution liquid phase transmission electron microscopy (TEM) down to the sub-nanometer level, I established my own research group at Lawrence Berkeley National Lab in 2010. My group focuses on developing and applying liquid phase TEM to investigate complex systems and reactions. We have studied a set of scientific problems centered on understanding how atomic level heterogeneity and fluctuations at solid-liquid interfaces impact nanoscale materials transformations using advanced liquid phase TEM. This article describes my personal journey in nanoscience, highlighting the main discoveries of my research group using liquid phase TEM as a unique tool. Some perspectives on the impacts of liquid phase TEM and the future opportunities in nanoscience and nanotechnology enabled by liquid phase TEM are also included.

Tilings and point sets arising from substitutions are classical mathematical models of quasicrystals. Their hierarchical structure allows one to obtain concrete answers regarding spectral questions tied to the underlying measures and potentials. In this review, we present some generalisations of substitutions, with a focus on substitutions on compact alphabets, and with an outlook towards their spectral theory. Guided by two main examples, we will illustrate what changes when one moves from finite to compact (infinite) alphabets, and discuss under which assumptions do we recover the usual geometric and statistical properties which make them viable models of materials with almost periodic order. We also present a planar example (which is a two-dimensional generalisation of the Thue−Morse substitution), whose diffraction is purely singular continuous.

This article deals with pure point diffraction and its connection to various notions of almost periodicity. We explain why the Fibonacci chain does not fit into the classical concept of Bohr almost periodicity and how it fits into the classes of mean, Besicovitch and Weyl almost periodic point sets. We report on recent results which characterize pure point diffraction as mean almost periodicity of the underlying structure, and discuss how the complex amplitudes fit into this picture.

This essay presents the viewpoint of the author on the topic of chirality and optical activity in nanostructures. It particularly focuses on the interaction of chiral molecules with plasmonic and excitonic nanocrystals and on induction of circular dichroism in such achiral nanocrystals. It discusses recent developments in the shape symmetry breaking of achiral metal nanostructures using photochemical processes induced by asymmetric localized plasmonic hot spots excited through circularly polarized light illumination. Finally, it addresses symmetry breaking in intrinsically chiral inorganic nanocrystals using chiral ligands during their formation, leading to 100 % enantiomeric excess in the nanocrystals of TbPO₄⋅H₂O. These nanocrystals exhibit an interesting nucleation mechanism, which leads to very high chiral amplification (secondary nucleation).

Changes in protein homeostasis are broadly implicated in many disease states, including amyloidoses, neurodegenerative diseases, cancer, and normal aging. Although this relationship has been fruitful for identifying and developing therapeutic strategies, it is challenging to identify which proteins are misfolding. New technologies have recently emerged that enable proteome-wide interrogation of protein conformation and stability. In this review, we describe these technologies, and how they have been used to identify proteins whose folding changes between disease states. We discuss some of the challenges in this emerging field, and the potential for misfolded protein profiling to provide insight into human disease.

The atomic-scale disorder of aperiodic crystals, and quasicrystals in particular, is inherently difficult to explore by experimental methods due to their complex atomic arrangements. Two advanced characterization techniques, a revived and an emerging one, offer direct experimental access even to such complex atomic structures: Diffuse Scattering and Atomic Resolution Holography. In this overview, we introduce their specific application to aperiodic crystals and discuss their merits and difficulties.

The cover art depicts the RNA catalyst ‘flexizyme’ based on its three-dimensional structure. It attaches a yellow sphere representing a non-canonical amino acid onto a tRNA, which is shown as a classical two-dimensional ‘cloverleaf’ representation. The catalyst is aided by two structural magnesium ions represented by small, darker red circles. Surrounding the flexizyme is a pool of acylated tRNA molecules and numerous macrocyclic peptides incorporating the non-canonical amino acids shown as colored circles.