Microscopic deformation processes determine defect formation on glass surfaces and, thus, the material's resistance to mechanical failure. While the macroscopic strength of most glasses is not directly dependent on material composition, local deformation and flaw initiation are strongly affected by chemistry and atomic arrangement. Aside from empirical insight, however, the structural origin of the fundamental deformation modes remains largely unknown. Experimental methods that probe parameters on short or intermediate length‐scale such as atom–atom or superstructural correlations are typically applied in the absence of alternatives. Drawing on recent experimental advances, spatially resolved Raman spectroscopy is now used in the THz‐gap for mapping local changes in the low‐frequency vibrational density of states. From direct observation of deformation‐induced variations on the characteristic length‐scale of molecular heterogeneity, it is revealed that rigidity fluctuation mediates the deformation process of inorganic glasses. Molecular field approximations, which are based solely on the observation of short‐range (interatomic) interactions, fail in the prediction of mechanical behavior. Instead, glasses appear to respond to local mechanical contact in a way that is similar to that of granular media with high intergranular cohesion.

In binary aluminosilicate liquids and glasses, heterogeneity on intermediate length scale is a crucial factor for optical fiber performance, determining the lower limit of optical attenuation and Rayleigh scattering, but also clustering and precipitation of optically active dopants, for example, in the fabrication of high-power laser gain media. Here, we consider the low-frequency vibrational modes of such materials for assessing structural heterogeneity on molecular scale. We determine the vibrational density of states VDoS g(ω) using low-temperature heat capacity data. From correlation with low-frequency Raman spectroscopy, we obtain the Raman coupling coefficient. Both experiments allow for the extraction of the average dynamic correlation length as a function of alumina content. We find that this value decreases from about 3.9 nm to 3.3 nm when mildly increasing the alumina content from zero (vitreous silica) to 7 mol%. At the same time, the average inter-particle distance increases slightly due to the presence of oxygen tricluster species. In accordance with Loewensteinian dynamics, this proves that mild alumina doping increases structural homogeneity on molecular scale.

The generation of optically active precipitates and quantum dots in glasses suitable for fiber application is a challenging task, in particular, for glasses which exhibit superbroad near‐infrared (NIR) photoemission. The latter can be achieved through dopants of heavy metal and post‐transition elements, but their stabilization in the desired chemical state requires unconventional approaches of synthesis. Here, atomic clusters of tellurium and metallic tellurium quantum dots in polyphosphate matrices are considered. Starting from the understanding of glass structure where the length and the degree of crosslinking of phosphate chains can be adjusted through composition, generation and stabilization of tellurium precipitates with ultra‐broadband infrared photoluminescence are demonstrated. Increased network crosslinking and, hence, increased molecular rigidity of the host enables finely distributed precipitates of optically active tellurium species. This demonstrates a generalist approach as to how the precipitation of metallic nanostructures can be tailored through network topology. In the present situation, the size of metallic tellurium inclusions can be limited to sub‐nanometric scale, enabling a luminescence bandwidth of about 260 nm across the telecommunication bands, and an emission lifetime of several tens of μs. In a demonstration experiment, it is shown that this strategy of structural control can be transferred to application in optical fiber.

Buildings represent more than 40% of Europe's energy demands and about one third of its CO2 emissions. Energy efficient buildings and, in particular, building skins have therefore been among the key priorities of international research agendas. Here, glass–glass fluidic devices are presented for large‐area integration with adaptive façades and smart windows. These devices enable harnessing and dedicated control of various liquids for added functionality in the building envelope. Combining a microstructured glass pane, a thin cover sheet with tailored mechanical performance, and a liquid for heat storage and transport, a flat‐panel laminate is generated with thickness adapted to a single glass sheet in conventional windows. Such multimaterial devices can be integrated with state‐of‐the‐art window glazings or façades to harvest and distribute thermal as well as solar energy by wrapping buildings into a fluidic layer. High visual transparency is achieved through adjusting the optical properties of the employed liquid. Also secondary functionality, such as chromatic windows, polychromatism, or adaptive energy uptake can be generated on part of the liquid.

This article aims to reduce huge pilot overhead when estimating the reconfigurable intelligent surface (RIS) relayed wireless channel. Motivated by the compelling grasp of deep learning in tackling nonlinear mapping problems, the proposed approach only activates a part of RIS elements and utilizes the corresponding cascaded channel estimate to predict another part. Through a synthetic deep neural network (DNN), the direct channel and active cascaded channel are first estimated sequentially, followed by the channel prediction for the inactive RIS elements. A three-stage training strategy is developed for this synthetic DNN. From simulation results, the proposed deep learning based approach is effective in reducing the pilot overhead and guaranteeing the reliable estimation accuracy.

Switchable windows provide intriguing opportunities for addressing the challenges of modern building skins. In particular, indoor comfort and the control of radiative heat transfer into and out of the building require adaptive and tunable solutions for shading and emissivity. Here, a switchable, ultrathin suspended particle device (SPD) for large‐area integration with smart facades is presented. The system is based on a fluidic window, manufactured at low cost from a laminate of structured, rolled glass and a thin cover with high surface strength. Loading the circulating fluid with magnetic nanoparticles enables active shading and solar‐thermal energy harvesting, whereby the loading state and, hence, the optical properties of the liquid can be controlled through remote switching in a particle collector‐suspender device. In the fully shaded state, a typical harvesting efficiency of 45% of the incoming solar power is obtained. For an average solar irradiance of 1000 W m−2 during 800 h a−1, this corresponds to a solar thermal harvesting capacity in the range of 360 kWh a−1 m−2. In comparison to alternative SPD concepts, this enables high flexibility and compatibility with established production lines. In addition, there is no need for further electrical contact, transparent conductive layers, or electrolytes.

Melting presents one of the most prominent phenomena in condensed matter science. Its microscopic understanding, however, is still fragmented, ranging from simplistic theory to the observation of melting point depressions. Here, a multimethod experimental approach is combined with computational simulation to study the microscopic mechanism of melting between these two extremes. Crystalline structures are exploited in which melting occurs into a metastable liquid close to its glass transition temperature. The associated sluggish dynamics concur with real‐time observation of homogeneous melting. In‐depth information on the structural signature is obtained from various independent spectroscopic and scattering methods, revealing a step‐wise nature of the transition before reaching the liquid state. A kinetic model is derived in which the first reaction step is promoted by local instability events, and the second is driven by diffusive mobility. Computational simulation provides further confirmation for the sequential reaction steps and for the details of the associated structural dynamics. The successful quantitative modeling of the low‐temperature decelerated melting of zeolite crystals, reconciling homogeneous with heterogeneous processes, should serve as a platform for understanding the inherent instability of other zeolitic structures, as well as the prolific and more complex nanoporous metal–organic frameworks.

improving the energy efficiency of a building is to minimize the heat exchange at the building interface. This is presently achieved through improvements on the building envelope, and facilitated through various material innovations, e.g., efficient thermal insulation materials, [11][12][13] emission-control coatings and surface layers, [14][15][16] or passive cooling systems which target enhancing the albedo of the urban environment, implemented either on the roof [17][18][19][20] or in façades. [21][22][23] Furthermore, active systems which adapt to environmental conditions are also studied, for example, chromogenics, [24][25][26][27][28][29][30] suspended particle devices, [29,31,32] liquid crystal devices, [29,31,[33][34][35] or evaporative or transpiration coolers. [36] Besides building envelopes, indoor cooling and air-conditioning systems represent a second area of major interest. This involves primarily the compensation of thermal load (originating from solar input as well as from electronic appliances, lighting, or human activity). Currently, the evacuation of latent and sensible heat is achieved using air-based cooling systems connected to chillers which operate with a fluid temperature of around 7-12 °C [37] and reach a seasonal performance factor of around 4. However, those systems are often conceived as being uncomfortable because of strong chill, convection, vertical gradients in air temperature, and noise. [38,39] Hydronic cooling systems for integration with building components (e.g., ceilings, walls, floors) are hence proposed as serious alternatives, enabling improvements on indoor comfort at significantly reduced energy consumption. [40][41][42][43] In this context, we now present a new type of hydronic system for sustainable cooling of indoor spaces and individual zones. Making use of visually transparent, large-area fluidic panels for wall, ceiling, and window integration, [44][45][46] we avoid negative effects such as draught or noise emitted by conventional air-conditioning systems which circulate cold and dry air. To facilitate significant reductions on energy consumption, the present system operates at very low flow rates and strongly reduced temperature gradients.As depicted in Figure 1, the device relies on cold water circulating through densely packed channels within a glassglass laminate such as recently reported for large-area integration with adaptive facades [44,47] or flat-panel algae reactors. [48] Adapted cooling performance is achieved by controlling the temperature and the flow rate of the circulating fluid, with More than 20% of the global energy demands are caused by heating, ventilating, and air conditioning in buildings. In particular during summer seasons and in warm climates, cooling loads are mostly neutralized by conventional air-conditioning systems. Due to often very low primary temperature, these require high energy input, cause significant noise, uncomfortably cool draughts, and vertical air temperature gradients. Here, an energy efficient planar cooling device for...