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Heat is almost everywhere. Unlike electricity, which can be easily manipulated, the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics. Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions; however, these strategies are less cost-effective and unscalable. Here, we spectroscopically demonstrate the glassy crystal state of 2-amino-2-methyl-1,3-propanediol (AMP) to realize an affordable, easily manageable approach for thermal energy recycling. The supercooled state of AMP is so sensitive to pressure that even several megapascals can induce crystallization to the ordered crystal, resulting in a substantial temperature increase of 48 K within 20 s. Furthermore, we demonstrate a proof-of-concept device capable of programable heating with an extremely high work-to-heat conversion efficiency of ∼383. Such delicate and efficient tuning of heat may remarkably facilitate rational utilization of waste heat.

Understanding composition-structure-property relationships is critical to developments and applications of novel microwave dielectric ceramics used in the field of wireless communications. Herein, a series of CeZr1·14Bi0.045A0.045Mo4·5O18 (abbreviated as CZA, A = Nb, Ta and Sb) ceramics were prepared through a solid-state reaction method. Density and scanning electron microscope results revealed dense and homogeneous microstructures. X-ray diffraction analysis indicated the formation of solid solutions. Accordingly, the effects of extrinsic factors were negligible and thus composition-structure-property relationships were systematically investigated by the combination of the chemical bond theory, Raman spectroscopy, far-infrared (FIR) spectroscopy and terahertz time-domain spectroscopy (THz-TDS) from an intrinsic perspective. Interestingly, the measured dielectric constants (εr) and quality factors (Q × f) are quite close to the extrapolated values from FIR and THz-TDS, and these values show a similar trend with varying components. In addition, Mo–O bonds play an important role in the coefficient of thermal expansion (α) and bond energy (E), and the composition dependent temperature coefficient of the resonance frequency (τf) can be well explained by variations of mean α and E of Mo–O bonds. Typically, excellent properties of Q × f = 116,485 GHz (at 9.58 GHz), εr = 9.91 and τf = −19.20 ppm °C−1 were achieved for the CZSb ceramic sintered at 700 °C. Notably, Q × f values of CZSb and CZTa ceramics are 6.13 and 4.16 times larger than that of the matrix, respectively. Ultra-high Q × f, low sintering temperatures (600 − 700 °C) and low εr make them potential candidates for low temperature co-fired ceramics (LTCC) applications.

Highlights This review systematically analyzes the effect of the electrolyte-to-sulfur ratios on battery energy density and the challenges for sulfur reduction reactions under lean electrolyte conditions. The strengths and limitations of different transition metal compounds are systematically presented and discussed from a fundamental perspective. Three promising strategies for sulfur hosts that act as anchors and catalysts are proposed to boost lean electrolyte Li–S battery performance.

Abstract Despite the importance of cell characterization and identification for diagnostic and therapeutic applications, developing fast and label‐free methods without (bio)‐chemical markers or surface‐engineered receptors remains challenging. Here, we exploit the natural cellular response to mild thermal stimuli and propose a label‐ and receptor‐free method for fast and facile cell characterization. Cell suspensions in a dedicated sensor are exposed to a temperature gradient, which stimulates synchronized and spontaneous cell‐detachment with sharply defined time‐patterns, a phenomenon unknown from literature. These patterns depend on metabolic activity (controlled through temperature, nutrients, and drugs) and provide a library of cell‐type‐specific indicators, allowing to distinguish several yeast strains as well as cancer cells. Under specific conditions, synchronized glycolytic‐type oscillations are observed during detachment of mammalian and yeast‐cell ensembles, providing additional cell‐specific signatures. These findings suggest potential applications for cell viability analysis and for assessing the collective response of cancer cells to drugs.

180° orientational disorder of molecular building blocks can lead to a peculiar spatial distribution of polar properties in molecular crystals. Here we present two examples [4-bromo-4′-nitrobiphenyl (BNBP) and 4-bromo-4′-cyanobiphenyl (BCNBP)] which develop into a bipolar final growth state. This means orientational disorder taking place at the crystal/nutrient interface produces domains of opposite average polarity for as-grown crystals. The spatial inhomogeneous distribution of polarity was investigated by scanning pyroelectric microscopy (SPEM), phase-sensitive second harmonic microscopy (PS-SHM) and selected volume X-ray diffraction (SVXD). As a result, the acceptor groups (NO2 or CN) are predominantly present at crystal surfaces. However, the stochastic process of polarity formation can be influenced by adding a symmetrical biphenyl to a growing system. For this case, Monte Carlo simulations predict an inverted net polarity compared with the growth of pure BNBP and BCNBP. SPEM results clearly demonstrate that 4,4′-dibromobiphenyl (DBBP) can invert the polarity for both crystals. Phenomena reported in this paper belong to the most striking processes seen for molecular crystals, demonstrated by a stochastic process giving rise to symmetry breaking. We encounter here further examples supporting the general thesis that monodomain polar molecular crystals for fundamental reasons cannot exist.

In ultrathin polymer films, the coupling between the segmental mobility, precursor of the molecular diffusion, and the crystallization rate is broken down because of interfacial interactions. In particular, in the presence of a reduced mobility layer at the interface with the substrate, the crystallization kinetics slow down at a length scale bigger than the one connected with the deviation from bulk behavior of the structural relaxation. By modeling the influence of the substrate interactions on the parameters governing the temperature evolution of the main relaxation time, it was possible to reproduce the effect of geometrical confinement on the quantities connected to the diffusion-limited crystallization rate. Upon reduction of the thickness or increasing of the substrate interaction, the films show an apparent higher glass stability in terms of an increase of the cold crystallization temperature and of the crystallization time. The deviations from bulk behavior were found to vanish above a crossover temperature as already observed for the phenomena connected to the glass transition. [ABSTRACT FROM AUTHOR]

Extremely thin films of poly(styrene) (h≤ 6 nm), in the geometry of “model” nanocomposites, show a continuous increase of the capacitance with temperature. This phenomenon is discussed in terms of a gradual defreezing of the interfacial zone between the so-called dead layer and the bulk. Such a mechanism shows a strong analogy to the dielectric response of the rigid amorphous fraction in semicrystalline materials. The defreezing process, foregoing the dynamic glass transition, is responsible for the temperature dependence of the deviations from bulk behavior. [ABSTRACT FROM AUTHOR]