In this review, we first briefly introduce the general knowledge of glass–ceramics, including the discovery and development, the application, the microstructure, and the manufacturing of glass–ceramics. Second, the review presents a detailed description of glass–ceramics in dentistry. In this part, the history, property requirements, and manufacturing techniques of dental glass–ceramics are reviewed. The review provided a brief description of the most prevalent clinically used examples of dental glass–ceramics, namely, mica, leucite, and lithium disilicate glass–ceramics. In addition, we also introduce the newly developed ZrO2–SiO2 nanocrystalline glass–ceramics that show great potential as a new generation of dental glass–ceramics. Traditional strengthening mechanisms of glass–ceramics, including interlocking, ZrO2–reinforced, and thermal residual stress effects, are discussed. Finally, a perspective and outlook for future directions in developing new dental glass–ceramics is provided to offer inspiration to the dental materials community.

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Ceramics is one of the oldest materials prepared and used by human beings. Ancient ancestors started to make pottery by forming and burning clay since the earliest civilizations. Ancient people started to fabricate burnt claywares since %6500 B.C., and clayware as a commercial product was available by %4000 B.C. [1] In modern society, as one of the largest branches in material family, ceramics have been developed and used in almost every fields of human beings' lives. In some senses, ceramics and metals possess complementary properties; generally, ceramics show the advantages of high strength, high hardness, high chemical stability, high wear resistance, whereas ceramics typically show intrinsic brittleness and poor plasticity due to their covalent and/or ionic chemical bonding; metals have good plasticity, high toughness, and high thermal and electronic conductivity; however, they typically show lower chemical stability and lower hardness than ceramics. It would be marvelous for a material to combine the properties of ceramics and metals. MAX phases are the materials that meet the challenge.MAX phases are a family of nanolaminate ternary nitrides and carbides, which were first discovered by Nowotny and his colleagues in Vienna. [2] In the beginning, MAX phases have a general formula of M nþ1 AX n (n ¼ 1-3), where M is a transition metal, A is an element from group A, and X is either carbon or nitrogen. The n value could be 1, 2, or 3, and the phases are named as 211, 312, and 413 MAX phases, respectively. These MAX phases show a hexagonal crystal structure (P63/mmc), consisting of M 6 X octahedra separated by A atomic layers. [3] M─X bonds in M 6 X octahedra are strong covalent bonds, whereas the M─A bonds between M 6 X and A atomic layer are much weaker, especially in shear. This unique bonding structure is analogous to graphite, and it is the special bonding structure that endows MAX phases properties of both ceramics and metals. On the one hand, MAX phases are stiff, lightweight, chemically stable, and oxidation resistant, which are the features of ceramics; on the other hand, they exhibit good electric and thermal conductivity as well as excellent machinability and damage tolerance, which are the features of metals.Unfortunately, MAX phases had not attracted enough attention in both academia and industry until 1996 when Barsoum et al. [4] synthesized and characterized Ti 3 SiC 2 . Ever since then, material researchers become more interested in this material. [5] In the past two decades, many MAX phases have been synthesized and tested to show highly unusual properties, [6] which will be discussed with detail in the following sections. The intensive extent of the researches on MAX phases can be demonstrated by the published papers (Figure 1). A remarkable jump can be observed between 1998 and 1999, and after that, the number of published papers increases steadily, reaching as high as 980 papers in 2019 (Figure 1a). From another aspect, the citation of the milestone paper published by Barsoum [4] also signific...

Two eye-movement experiments are reported in which a boundary paradigm was used to manipulate the presence versus absence of boundaries for high-frequency and low-frequency target words in the parafovea. In Experiment 1, this was done by introducing a blank space after the target words, whereas in Experiment 2 this was done by rendering the target words in red. In both experiments, higher frequency targets engendered longer saccades, whereas the presence of parafoveal word boundaries engendered shorter saccades. This pattern suggests the operation of two countermanding saccade-targeting mechanisms: one that uses parafoveal processing difficulty to adjust saccade lengths and a second that uses word boundaries to direct the eyes toward specific saccade targets. The implications of these findings for models of eye-movement control during reading are discussed, as are suggestions for integrating dynamic-adjustment and default-targeting accounts. Keywords Chinese reading. Dynamic-adjustment model. Eye-movement control. Word segmentation Skilled reading requires the coordination of lexical processing with eye movements to rapidly extract visual information from the printed page. One important aspect of this coordination is saccade targeting, or the Bdecisions^about where to move the eyes. Because much of what has been learned about eyemovement control in reading has come from studies involving alphabetic writing systems, models of how readers decide where to move their eyes have been informed largely by what has been learned from studying languages like English and German, where the eyes seem to be directed toward a small number of default targets (e.g., see Engbert, Nuthmann, Ricter, & Kliegl, 2005; Reichle, Pollatsek, & Rayner, 2012). For example, with English, readers seem to direct their eyes slightly to the left of a word's center, toward the preferred-viewing location (PVL;