Institute of Materials Science

Subcooled flow boiling of distilled water was investigated in a vertical annular minichannel with smooth and surface-modified heated tubes. Copper and stainless-steel substrates were tested with ZnO and ZnO/PMHS coatings; Al2O3 was additionally tested on stainless steel. A simplified one-dimensional cylindrical model provided local effective heat transfer coefficients, and modified surfaces were compared pointwise with smooth references at matched operating conditions and axial positions. A modification was considered favourable only when the heat transfer coefficient increased without an increase in wall temperature. ZnO on stainless steel was the only modification meeting this criterion at both nominal mass flow rates: the mean pointwise coefficient increased by 44.2% at 7 kg/h and 42.9% at 10 kg/h, while mean wall temperature decreased by 36.9 and 32.8 K, respectively. Al2O3 and ZnO/PMHS on stainless steel reduced the coefficient and increased wall temperature, whereas copper modifications showed no robust improvement relative to the designated references. A separate model-sensitivity assessment did not alter the qualitative ranking. ZnO-modified stainless steel was therefore the best-performing configuration within the tested matrix; no broader superiority is claimed beyond the present geometry, fluid, flow rates, and heat-flux range.

3,5-Dicyanopyridine and phenothiazine derivatives exhibit attractive mechanochromic properties that enable multicolour emissions and single-molecular white emission. Large hypsochromic shifts of up to 190 nm (from red to deep blue) were observed in the developed mechanochromic compounds in response to various external stimuli. These derivatives exhibit record-breaking solid-state emission enhancement factors of up to 755, indicating that the emission intensity of their solids is substantially higher than that of solutions. Single-molecular white light emitting samples were obtained by the tuning of the substituent nature in the pyridine ring and physical approaches (different treatments of aggregate-containing liquids and solid samples). The developed compounds possess different conformational states, with emissions ranging from deep blue to red. The amorphous states exhibit single-colour emissions, while crystalline states of various packing arrangements show white or multicoloured emissions. They can be used as down-conversion white emitters in white light-emitting diodes exhibiting colour coordinates of (0.32, 0.34), (0.28, 0.30) and (0.32, 0.38), colour rendering index (CRI) of 75–78 and colour temperatures in the range from 5368 to 6668 K.

Early detection of lithium-ion battery (LIB) electrolyte leakage in the vapor phase is important for battery safety, yet vapor-phase surface-enhanced Raman spectroscopy (SERS) remains challenging because weak gas–surface interactions limit analyte residence within plasmonic hot spots. Here, we report a hybrid graphene/plasmonic SERS platform for vapor-phase detection of LIB electrolyte components based on periodic Ag nanoparticle (AgNP) multimer arrays integrated with a monolayer graphene overlayer. The substrate is fabricated by capillary-assisted particle assembly (CAPA) followed by a unified poly(vinyl alcohol) (PVA)-assisted hot-press transfer process, enabling both the transfer of ordered AgNP arrays to glass and spatially selective graphene integration. This approach preserves nanoscale ordering while creating a four-region architecture on a single chip, allowing the individual and combined contributions of graphene and the plasmonic array to be evaluated under identical vapor-exposure conditions. Optical characterization shows a broadband plasmonic response dominated by interparticle coupling within AgNP multimers, with spectral overlap across the 532 nm excitation and Raman-scattering window. Upon exposure to vapors from a commercial LiPF6 electrolyte containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC), no analyte-attributable Raman features are observed from bare glass, graphene on glass, or the AgNP array alone. In contrast, the graphene-coated AgNP region yields clear vapor-phase Raman signatures assignable to both EC and EMC. These results show that detectable vapor-phase electrolyte signatures emerge only from the combined graphene–plasmonic architecture, consistent with a hybrid interfacial effect in which graphene may increase the local surface population of volatile molecules while the AgNP multimers provide localized electromagnetic enhancement. This work establishes a scalable hybrid-transfer strategy for ordered vapor-phase SERS substrates and highlights graphene-coated plasmonic arrays as promising material platforms for molecularly specific LIB leak detection.