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FRACTURE MECHANISM IN SOFT MATERIALS REVEALED Researchers led by a team at the Polytechnic University of Milan developed a new theory they say has finally deciphered the physical mechanisms of [...]

Building on previous work, researchers at the University of Tsukuba, Japan, developed a new time-resolved atomic force microscopy (AFM) system, enhancing operability by merging AFM with their unique ultrashort laser [...]

Author(s): Catxere A. Casacio [sup.1] , Lars S. Madsen [sup.1] , Alex Terrasson [sup.1] , Muhammad Waleed [sup.1] , Kai Barnscheidt [sup.2] , Boris Hage [sup.2] , Michael A. Taylor [...], The performance of light microscopes is limited by the stochastic nature of light, which exists in discrete packets of energy known as photons. Randomness in the times that photons are detected introduces shot noise, which fundamentally constrains sensitivity, resolution and speed.sup.1. Although the long-established solution to this problem is to increase the intensity of the illumination light, this is not always possible when investigating living systems, because bright lasers can severely disturb biological processes.sup.2-4. Theory predicts that biological imaging may be improved without increasing light intensity by using quantum photon correlations.sup.1,5. Here we experimentally show that quantum correlations allow a signal-to-noise ratio beyond the photodamage limit of conventional microscopy. Our microscope is a coherent Raman microscope that offers subwavelength resolution and incorporates bright quantum correlated illumination. The correlations allow imaging of molecular bonds within a cell with a 35 per cent improved signal-to-noise ratio compared with conventional microscopy, corresponding to a 14 per cent improvement in concentration sensitivity. This enables the observation of biological structures that would not otherwise be resolved. Coherent Raman microscopes allow highly selective biomolecular fingerprinting in unlabelled specimens.sup.6,7, but photodamage is a major roadblock for many applications.sup.8,9. By showing that the photodamage limit can be overcome, our work will enable order-of-magnitude improvements in the signal-to-noise ratio and the imaging speed. A quantum microscope obtains signal-to-noise beyond the photodamage limits of conventional microscopy, revealing biological structures within cells that would not otherwise be resolved.

Author(s): Youngjoon Choi [sup.1] [sup.2] [sup.3] , Hyunjin Kim [sup.1] [sup.2] [sup.3] , Yang Peng [sup.4] , Alex Thomson [sup.2] [sup.3] [sup.5] , Cyprian Lewandowski [sup.2] [sup.3] [sup.5] , Robert [...], Magic-angle twisted bilayer graphene (MATBG) exhibits a range of correlated phenomena that originate from strong electron-electron interactions. These interactions make the Fermi surface highly susceptible to reconstruction when [plus or minus]1, [plus or minus]2 and [plus or minus]3 electrons occupy each moiré unit cell, and lead to the formation of various correlated phases.sup.1-4. Although some phases have been shown to have a non-zero Chern number.sup.5,6, the local microscopic properties and topological character of many other phases have not yet been determined. Here we introduce a set of techniques that use scanning tunnelling microscopy to map the topological phases that emerge in MATBG in a finite magnetic field. By following the evolution of the local density of states at the Fermi level with electrostatic doping and magnetic field, we create a local Landau fan diagram that enables us to assign Chern numbers directly to all observed phases. We uncover the existence of six topological phases that arise from integer fillings in finite fields and that originate from a cascade of symmetry-breaking transitions driven by correlations.sup.7,8. These topological phases can form only for a small range of twist angles around the magic angle, which further differentiates them from the Landau levels observed near charge neutrality. Moreover, we observe that even the charge-neutrality Landau spectrum taken at low fields is considerably modified by interactions, exhibits prominent electron-hole asymmetry, and features an unexpectedly large splitting between zero Landau levels (about 3 to 5 millielectronvolts). Our results show how strong electronic interactions affect the MATBG band structure and lead to correlation-enabled topological phases. Correlation-driven topological phases with different Chern numbers are observed in magic-angle twisted bilayer graphene in modest magnetic fields, indicating that strong electronic interactions can lead to topologically non-trivial phases.

Over the past few years, metal additive manufacturing (AM) technologies including laser powder bed fusion (LPBF) have benefited from high interest in both research and industry [1,2]. LPBF relies on [...]

Multilayered materials are commonly used across various sectors, such as the packaging, construction, and medical industries. However, multilayered structures may alter the mechanical, acoustic, and optical properties of these materials. [...]

Abstract. Dual-view inverted selective plane illumination microscopy (diSPIM) enables high-speed, long-term, four-dimensional (4D) imaging with isotropic spatial resolution. It is also compatible with conventional sample mounting on glass coverslips. However, [...]

This work proposes an analytical method to identify plant species based on microscopy images of the midrib cross-section of leaves. Unlike previous shape-based approaches based on the individual shape of external contours and cells, an architectural analysis is proposed, where the midrib is semi-automatically segmented and partitioned into histologically relevant structures composed of layers of cells and vascular structures. Using a sequence of morphological operations, a set of geometrical measures from the cells in each layer is extracted to produce a vector of features for species categorization. The method applied to a database containing 10 species of plants from the Brazilian flora achieved a success rate of 91.7%, outperforming other classical shape-based approaches published in the literature. Key words: automatic species identification, image analysis, morphological features. Les auteurs de ce travail proposent une methode analytique permettant d'identifier une espece vegetale a partir d'images en microscopie de coupes transversales de la nervure mediane des feuilles. Contrairement aux approches precedentes basees sur la forme qui reposent sur la forme individuelle des contours externes et sur les cellules, une analyse architecturale est proposee, dans laquelle la nervure mediane est segmentee de maniere semi-automatique et divisee en structures histologiquement pertinentes composees de couches cellulaires et de structures vasculaires. En utilisant une sequence d'operations morphologiques, une serie de mesures geometriques des cellules de chaque couche est extraite afin de produire un ensemble de caracteristiques pour categoriser les especes. La methode appliquee a une base de donnees contenant 10 especes de plantes issues de la flore du Bresil a obtenu un taux de succes de 91.7%, surpassant les autres approches classiques basees sur la forme publiees dans la litterature. [Traduit par la Redaction] Mots-cles : identification automatisee d'une espece, analyse d'image, caracteristiques morphologiques., Introduction The categorization of plants into species is an important taxonomical task; it provides meaningful information about particular characteristics of a species, which can be used in the context of [...]

Non-invasive imaging deep into organs at microscopic scales remains an open quest in biomedical imaging. Although optical microscopy is still limited to surface imaging owing to optical wave diffusion and [...]