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Naturally occurring spatiotemporal patterns typically have a predictable pattern design and are reproducible over several cycles. However, the patterns obtained from artificially designed out-of-equilibrium chemical oscillating networks (such as the Belousov–Zhabotinsky reaction for example) are unpredictable and difficult to control spatiotemporally, albeit reproducible over subsequent cycles. Here, we show that it is possible to generate reproducible spatiotemporal patterns in out-of-equilibrium chemical reactions and self-assembling systems in water in the presence of sound waves, which act as a guiding physical stimulus. Audible sound-induced liquid vibrations control the dissolution of atmospheric gases (such as O2 and CO2) in water to generate spatiotemporal chemical patterns in the bulk of the fluid, segregating the solution into spatiotemporal domains having different redox properties or pH values. It further helps us in the organization of transiently formed supramolecular aggregates in a predictable spatiotemporal manner.Patterns formed by artificial out-of-equilibrium chemical oscillating networks (such as the Belousov–Zhabotinsky reaction) are difficult to control with any precision. Now, it has been shown that low-intensity audible sound can be used to generate spatiotemporal patterns with a programmable distribution of redox- and pH-responsive chemical systems and supramolecular assemblies in solution.

GaAs-on-Si templates with two different dislocation filter layers (DFLs) were grown at 550 °C low-temperature (LT)-DFL and 660 °C high-temperature (HT)-DFL using metal organic vapor-phase epitaxy and the effects of the growth temperature were studied. The threading dislocation density (TDD) values of LT-DFL and HT-DFL were 5.2 × 107 cm−2 and 1.5 × 107 cm−2, respectively. The 1.5 × 107 cm−2 of TDD in HT-DFL is reduced by almost one order compared to the 1.2 × 108 cm−2 of that in the control sample without DFLs. The annihilation process was mainly observed in the HT-DFL by a transmission electron microscope, resulting in a lower TDD. The 500-nm-thick GaAs bulk layer and InAs QDs were regrown on GaAs-on-Si templates and the optical properties were also evaluated by photoluminescence (PL). The highest PL peak intensity of the HT-DFL indicates that less non-radiative recombination in both the GaAs bulk and QDs occurred due to the reduced TDD. The GaAs p–i–n diodes were also fabricated to analyze the bulk leakage (JB) and the surface leakage current. The JB of HT-DFL shows the lowest value of 3.625 × 10–7 A/cm−2 at applied bias voltage of 1 V, which is 20 times lower than the JB of the control sample without DFLs. This supports that the high-temperature growth of DFL can make a good performance GaAs device on Si.

The molecular host cucurbit[7]uril forms an extremely stable inclusion complex with the dicationic ferrocene derivative bis(trimethylammoniomethyl)ferrocene in aqueous solution. The equilibrium association constant for this host-guest pair is 3 x 10¹⁵ M⁻¹ (Kd = 3 x 10⁻¹⁶ M), equivalent to that exhibited by the avidin-biotin pair. Although purely synthetic systems with larger association constants have been reported, the present one is unique because it does not rely on polyvalency. Instead, it achieves its extreme affinity by overcoming the compensatory enthalpy-entropy relationship usually observed in supramolecular complexes. Its disproportionately low entropic cost is traced to extensive host desolvation and to the rigidity of both the host and the guest.

White light-emitting diodes (LEDs) are becoming an alternative general light source, with huge energy savings compared to conventional lighting. However, white LEDs using phosphor(s) suffer from unavoidable Stokes energy converting losses, higher manufacturing cost, and reduced thermal stability. Here, we demonstrate electrically driven, phosphor-free, white LEDs based on three-dimensional gallium nitride structures with double concentric truncated hexagonal pyramids. The electroluminescence spectra are stable with varying current. The origin of the emission wavelength is studied by cathodoluminescence and high-angle annular dark field scanning transmission electron microscopy experiments. Spatial variation of the carrier injection efficiency is also investigated by a comparative analysis between spatially resolved photoluminescence and electroluminescence. White LEDs: phosphor-free LEDs with stable white emission Phosphor-free white light-emitting diodes (LEDs) are realized that are based on gallium nitride (GaN) structures and exhibit stable color emission. White LEDs are fast replacing conventional lighting due to the very significant energy savings they offer, but phosphor-based white LEDs suffer from inherent conversion losses, high manufacturing cost, and poor thermal stability. Now, Yong-Hoon Cho and co-workers at Korea Advanced Institute of Science and Technology (KAIST) in South Korea have demonstrated electrically driven phosphor-free white LEDs with stable color emission. The LEDs contain gallium nitride structures with double concentric truncated hexagonal pyramids grown by metal-organic vapor-phase epitaxy. Each facet of a pyramid emits a different wavelength. The LEDs were found to consistently emit white light with relatively stable CIE color coordinates when the injection current was varied.

The high-pressure elasticity of Baltic amber was investigated up to ∼12 GPa for the first time by using Brillouin spectroscopy. Two scattering geometries were adopted to derive the pressure dependence of the mode frequency of longitudinal acoustic waves, the longitudinal sound velocity, the refractive index and the density. These properties showed rapid changes at low pressures below ∼4 GPa while their changes were more sluggish at higher pressures. This crossover behavior was attributed to the collapse of free volume, which seems to be a rather common behavior of many amorphous materials. Since Baltic amber is a unique glass produced by vitrification under extremely long time, the first investigation of high-pressure elasticity reported in this study may be a good starting point for further in-depth research in this super-aged glassy system.

The quantum plasmonics field has emerged and been growing increasingly, including study of single emitter–light coupling using plasmonic system and scalable quantum plasmonic circuit. This offers opportunity for the quantum control of light with compact device footprint. However, coupling of a single emitter to highly localized plasmonic mode with nanoscale precision remains an important challenge. Today, the spatial overlap between metallic structure and single emitter mostly relies either on chance or on advanced nanopositioning control. Here, we demonstrate deterministic coupling between three-dimensionally nanofocused plasmonic modes and single quantum dots (QDs) without any positioning for single QDs. By depositing a thin silver layer on a site-controlled pyramid QD wafer, three-dimensional plasmonic nanofocusing on each QD at the pyramid apex is geometrically achieved through the silver-coated pyramid facets. Enhancement of the QD spontaneous emission rate as high as 22 ± 16 is measured for all processed QDs emitting over ∼150-meV spectral range. This approach could apply to high fabrication yield onchip devices for wide application fields, e.g., high-efficiency light-emitting devices and quantum information processing.

High-pressure Brillouin spectroscopy was applied to clarify quantitatively the physical and mechanical differences of a polymer with distinct structures consisting of the same elements. The pressure dependences of elastic properties, Young’s modulus, the shear modulus, the bulk modulus, and Poisson’s ratio for an amorphous poly (-ethylene terephthalate-) [(-PET-)] and a semi-crystalline PET were compared for pressures up to 11 GPa. A collapse of the free volume for the two PETs was ascertained at the different values of the pressure with different slopes for the elastic properties, Young’s modulus, the shear modulus, and the bulk modulus. Although the Poisson’s ratios of a semi-crystalline PET increased linearly with increasing pressure, those of an amorphous PET were almost constant. The P-V equation of state (EOS) for an amorphous PET was also determined, and isothermal bulk moduli extracted from the Birch-Murnaghan and the Vinet EOSs were 6.3 ± 0.2 GPa and 6.7 ± 0.1 GPa, respectively.

Clostridium perfringens forms metabolically dormant endospores that withstand extreme environmental conditions. Small acid-soluble proteins (SASPs) are ubiquitous DNA-binding proteins in endospores that promote resistance. While their protective role has been previously characterized, we aimed to provide further biophysical insight into the nature of these interactions, focusing on variant-specific structural dynamics through novel single-molecule and NMR approaches. Here, we characterize the DNA-binding properties and structural features of two Ssp4 variants using single-molecule fluorescence imaging and NMR spectroscopy along with electrophoretic mobility shift assays (EMSA). Both Ssp4 variants bind DNA cooperatively, but single-molecule analysis revealed preferential binding to GC-rich regions and significantly increased residence time in the presence of dipicolinic acid (DPA). NMR analysis reveals that an aspartic acid residue at position 36 (D36) stabilizes the Ssp4 structure, and its removal induces local structural perturbations without altering DNA affinity. Our findings provide molecular insights into how Ssp4 variants protect DNA in substantially dehydrated endospores and promote spore survival.

The elastic properties of a biocompatible silk film were investigated under temperature and pressure variations by using Brillouin spectroscopy. The Brillouin frequency shift decreased monotonically upon heating and showed a sudden change at the glass transition temperature. The existence of water molecules in the film increased the longitudinal modulus by approximately 10% and induced a relaxation peak in the hypersonic damping at ~60 ◦ C. The pressure dependences of the sound velocities of the longitudinal and the transverse acoustic modes and the refractive index were determined for the first time at pressures up to ~15.5 GPa. All these properties increased upon compression; these changes indicated that the free volume in the silk film collapsed at a pressure of about 3 GPa.