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Interlayer excitons (ILXs) — electron–hole pairs bound across two atomically thin layered semiconductors — have emerged as attractive platforms to study exciton condensation 1 – 4 , single-photon emission and other quantum information applications 5 – 7 . Yet, despite extensive optical spectroscopic investigations 8 – 12 , critical information about their size, valley configuration and the influence of the moiré potential remains unknown. Here, in a WSe 2 /MoS 2 heterostructure, we captured images of the time-resolved and momentum-resolved distribution of both of the particles that bind to form the ILX: the electron and the hole. We thereby obtain a direct measurement of both the ILX diameter of around 5.2 nm, comparable with the moiré-unit-cell length of 6.1 nm, and the localization of its centre of mass. Surprisingly, this large ILX is found pinned to a region of only 1.8 nm diameter within the moiré cell, smaller than the size of the exciton itself. This high degree of localization of the ILX is backed by Bethe–Salpeter equation calculations and demonstrates that the ILX can be localized within small moiré unit cells. Unlike large moiré cells, these are uniform over large regions, allowing the formation of extended arrays of localized excitations for quantum technology. Imaging the electron and hole that bind to form interlayer excitons in a 2D moiré material enables direct measurement of its diameter and indicates the localization of its centre of mass.

Background This study aimed to evaluate the knowledge of non-dental health profession students regarding the etiology and management of gingival pigmentation, and determine the ability of health professions students in different disciplines to assess levels of gingival pigmentation when they viewed intraoral clinical photographs of patients. Methods A cross-sectional, pre-tested, and validated survey was conducted among non-dental health professional students to assess knowledge. Visual perception was evaluated using a collection of intraoral clinical images classified according to the Dummett-Gupta Oral Pigmentation index (DOPI) and a visual analog scale. Statistical significance was set at the 5% level. Results There were no significant differences based on nationality or sex in knowledge of the causes and treatment of gingival pigmentation. However, significant differences were observed among students from different health professions educational programs. Moreover, students’ visual assessment of clinical cases varied in comparison to the actual DOPI scores assigned by experienced clinicians, possibly because of their subjective visual perception of esthetics. Conclusions Although the students demonstrated reasonable comprehension of the etiology of gingival pigmentation, their knowledge of treatment options was limited. Visual pigmentation assessment saw individual variations depending on cultural background and societal acceptance. The findings of this study provide insights into the subjectivity of perception of gingival pigmentation, which varies among individuals in reference to a validated categorical classification.

The most crucial event in a mining project is the selection of an appropriate mining method (MMS). Consequently, determining the optimal choice is critical because it impacts most of the other key decisions. This study provides a concise overview of the development of multiple selection methods using a cascade-forward backpropagation neural network (CFBPNN). Numerous methods of multicriteria decision-making (MCDM) are discussed and compared herein. The comparison includes several factors, such as applicability, subjectivity, qualitative and quantitative data, sensitivity, and validity. The application of artificial intelligence is presented and discussed using CFBPNN. The Chengchao iron mine was selected for this investigation to pick the optimum mining method. The results revealed that cut and fill stoping is the most appropriate mining method, followed by sublevel and shrinkage stoping methods. The least appropriate method is open-pit mining, followed by room and pillar and longwall mining methods.

Gingival bleeding, which was not previously present, may be a preceding symptom associated with COVID‐19 infections, preceding or coincidental with fever, other clinical signs, and positive testing. Gingival bleeding, which was not previously present, may be a preceding symptom associated with COVID‐19 infections, preceding or coincidental with fever, other clinical signs, and positive testing.

Purpose This paper aims to find a suitable solution to treat the solidification paper by using hydroxypropyl cellulose (HPC) to improve the mechanical, physical and chemical properties of paper. Design/methodology/approach The samples have gone several stages, starting with the manufacture of paper from the linen pulp and the same components of the hardened manuscript papers. It was subjected to artificial aging to reach an age comparable to the manuscript age, then it was subjected to natural aging by inoculation it with A. niger. Mechanical cleaning of the leaves was done with soft brushes. The samples have been consolidated by HPC 2%. Digital microscopy, scanning electron microscopy, mechanical properties measurement, color change, Fourier transform infrared and pH measurements were used to assess the effect of HPC on the qualities of leaves. Findings HPC succussed in strengthening and restoring the natural, chemical and mechanical properties for the solidified leaves. Originality/value The solidified papers phenomenon constitutes severe suffering for manuscripts and books conservators. The paper consolidation initial stage is one of the most important conservation stages because paper has lost many natural, mechanical and chemical properties. The most important feature of this study is providing a solution to the hardened leaves strengthening problem and restoring their chemical, natural and mechanical properties.

Purpose The purpose of this study is to find an applicable solution for the consolidation of petrified paper after disassembling it to complete other stages of treatment. Design/methodology/approach The samples were subjected to natural aging by being inoculated with Aspergillus niger until they reached the stage of adhesion and petrification. After that, the leaves were separated, and cellulose nanocrystals were applied, then the leaves were subjected to wet thermal aging for 21 days. Digital microscope, scanning electron microscope, mechanical properties measurement, measurement of color change, Fourier transform infrared spectroscopy and pH measurement were used to evaluate the effects of the cellulose nanocrystal on paper. Findings The results proved that cellulose nanocrystal (5%) successes consolidation of petrified paper Without affecting its natural, mechanical and chemical properties. Originality/value This study was based on the effectiveness of cellulose nanocrystal in strengthening the petrified papers and testing its effect on the physical, mechanical and chemical paper properties.

Purpose Paper aims to determinate caking paper manuscript cause through studying of the manuscript components, bio-deterioration and physio-chemical deterioration factor. It will facilitate manuscripts and paper conservators to understand paper blocking and caking phenomenon. Design/methodology/approach The manuscript condition has been diagnosed by focusing on adhesion and fossilization regions. To achieve this, some methods of analysis and examination were used, such as visual examination, digital microscopy and scanning electron microscope were used to studying surface changes. X-ray diffraction and Fourier transform infrared microscopy were used to determinate of cellulose crystallinity, ink composition and identify the binding medium. Findings The results revealed the use of cotton pulp, and calcium carbonate was among the fillers that were used to improve the properties of paper. The crystallization of cellulose was lower in the first and last papers than the papers located in the heart of the manuscript. The most important reasons that led to the papers caking was the presence of fungi A. niger, Cladosporium sp, Chaetomium sp, by secreting some enzymes in combination with some other factors such as difference variation in temperature and moisture. Originality/value All deterioration factors participate with each other until rule the damage circle of the papers because one factor alone cannot stick the papers. It was inferred from the examinations and analyzes that were conducted for the samples.

The ability to withstand accidental loads without disproportionate collapse, i.e. robustness, is a necessary characteristic of any structure. Previous studies have demonstrated that the robustness of steel frames during fire is controlled primarily by the rotational capacity of beam to column connections. Higher values of rotational capacity allow the beam to develop catenary action which enhances the survivability of the steel frame during fire. Over the last two decades several inroads have been made to increase the rotational capacity of beam to column connections during fire. The previous methods improved the rotational capacity by either changing the connection types or topology while overlooking the contribution of the bolt assembly (bolt and nut) to the behaviour, despite the fact that the frequent failure mode of connections reported in the literature is the bolt failure.In this study, the rotational capacity is enhanced by improving the contribution of bolts. One feasible method is to eliminate the brittle failure mode of the bolt assembly i.e. stripping. A detailed FE study is initially presented investigating the factors affecting the failure modes of high strength and stainless steel bolt assemblies under tensile force. It was concluded that the stripping failure is primarily controlled by the thread length in the grip, the further the nut distance from the shank, the higher the resistance to stripping. The effect of stripping failure on the ductility of end plate beam to column connections was also numerically investigated at ambient and elevated temperatures. It was concluded that the rotational capacity of a connection can be 5.0 times higher if stripping failure is avoided, particularly at elevated temperatures.Another feasible method to improve the rotational capacity of connections is to increase the deformation capacity of the bolt assembly, the higher the bolt's elongation, the higher the rotational capacity that can be achieved. By inserting a steel sleeve with a designated length, thickness and wall curvature between the end plate and the washer, the load path between the end plate and the bolts can be interrupted, promoting a more ductile response. End plate connections with various sleeve geometries were numerically investigated using a validated FE model at ambient and elevated temperatures. The proposed system substantially enhances the rotational capacity up to 3.46 times that of the standard connection. An elastic response consistent with standard connections is maintained indicating that the proposed system is compatible with existing codified elastic design approaches without modification. An analytical solution was also proposed to predict the geometric parameter of a sleeve with a circular waveform. The sleeve is mathematically represented using shell of revolution theories under axisymmetric load. The comparison between the proposed analytical solution with validated FE models show that the predicted rotational capacity based on the analytical solution is very conservative, however with a significantly higher rotation capacity than that of the standard configuration.

Interlayer excitons (ILXs) - electron-hole pairs bound across two atomically thin layered semiconductors - have emerged as attractive platforms to study exciton condensation, single-photon emission and other quantum-information applications. Yet, despite extensive optical spectroscopic investigations, critical information about their size, valley configuration and the influence of the moiré potential remains unknown. Here, we captured images of the time- and momentum-resolved distribution of both the electron and the hole that bind to form the ILX in a WSe2/MoS2 heterostructure. We thereby obtain a direct measurement of the interlayer exciton diameter of ~5.4 nm, comparable to the moiré unit-cell length of 6.1 nm. Surprisingly, this large ILX is well localized within the moiré cell to a region of only 1.8 nm - smaller than the size of the exciton itself. This high degree of localization of the interlayer exciton is backed by Bethe-Salpeter equation calculations and demonstrates that the ILX can be localized within small moiré unit cells. Unlike large moiré cells, these are uniform over large regions, thus allowing the formation of extended arrays of localized excitations for quantum technology.

An exciton, a two-body composite quasiparticle formed of an electron and hole, is a fundamental optical excitation in condensed-matter systems. Since its discovery nearly a century ago, a measurement of the excitonic wavefunction has remained beyond experimental reach. Here, we directly image the excitonic wavefunction in reciprocal space by measuring the momentum distribution of electrons photoemitted from excitons in monolayer WSe2. By transforming to real space, we obtain a visual of the distribution of the electron around the hole in an exciton. Further, by also resolving the energy coordinate, we confirm the elusive theoretical prediction that the photoemitted electron exhibits an inverted energy-momentum dispersion relationship reflecting the valence band where the partner hole remains, rather than that of conduction-band states of the electron.