Blast resistance evaluation of urban utility tunnel reinforced with BFRP bars

To improve corrosion-resistance of shallow-buried concrete urban utility tunnels(UUTs),basalt fiber reinforced polymer(BFRP)bars are applied to reinforce UUTs.As the UUT must have excellent survival capability under accidental explosions,a shallow-buried BFRP bars reinforced UUT(BBRU)was designed and constructed.Repetitive blast experiments were carried out on this BBRU.Dynamic responses,damage evolutions and failure styles of the BBRU under repetitive explosions were revealed.The tunnel roof is the most vulnerable component and longitudinal cracks develop along the tunnel.When the scaled distance is larger than 1.10 m/kg1/3,no cracks are observed in the experiments.When the BBRU is severely damaged,there are five cracks forming and developing along the roof.The roof is simplified as a clamped-supported one-way slab,proved by the observation that the maximum strain of the transverse bar is much larger than that of the longitudinal bar.Dynamic responses of the roof slab are predicted by dynamic Euler beam theory,which can consistently predict the roof displacement under large-scaleddistance explosion.Compared with the UUT reinforced with steel bars,the BBRU has advantages in blast resistance with smaller deflections and more evenly-distributed cracks when the scaled distance is smaller than 1.260 m/kg1/3 and the steel bars enter plastic state.Longer elastic defamation of the BFRP bars endows the UUT more excellent blast resistance under small-scaled-distance explosions.

Geometric phase-encoded stimuli-responsive cholesteric liquid crystals for visualizing real-time remote monitoring:humidity sensing as a proof of concept

Liquid crystals are a vital component of modern photonics,and recent studies have demonstrated the exceptional sensing properties of stimuli-responsive cholesteric liquid crystals.However,existing cholesteric liquid crystal-based sensors often rely on the naked eye perceptibility of structural color or the measurement of wavelength changes by spectrometric tools,which limits their practical applications.Therefore,developing a platform that produces recognizable sensing signals is critical.In this study,we present a visual sensing platform based on geometric phase encoding of stimuli-responsive cholesteric liquid crystal polymers that generates real-time visual patterns,rather than frequency changes.To demonstrate this platform’s effectiveness,we used a humidity-responsive cholesteric liquid crystal polymer film encoded with a q-plate pattern,which revealed that humidity causes a shape change in the vortex beam reflected from the encoded cholesteric liquid crystal polymers.Moreover,we developed a prototype platform towards remote humidity monitoring benefiting from the high directionality and long-range transmission properties of laser beams carrying orbital angular momentum.Our approach provides a novel sensing platform for cholesteric liquid crystals-based sensors that offers promising practical applications.The ability to generate recognizable sensing signals through visual patterns offers a new level of practicality in the sensing field with stimuli-responsive cholesteric liquid crystals.This platform might have significant implications for a broad readership and will be of interest to researchers working in the field of photonics and sensing technology.

Dynamic coloration of polymerized cholesteric liquid crystal networks by infiltrating organic compounds

We demonstrate the dynamic coloration of polymerized cholesteric liquid crystal(PCLC)networks templated by the“wash-out/refill”method in the presence of organic compounds.The reflection colors were modulated by two key approaches,that is,the injection of mutually soluble organic fluids into a microfluidic channel and the diffusion of volatile organic compounds(VOCs).The reversible tuning of reflected colors with central wavelengths between~450 nm and~600 nm was achieved by alternative injection of nematic liquid crystal E7(n_(av)=1.64)and benzyl alcohol(n=1.54)using syringe pumps.The fascinating iridescence with reflection centers from~620 nm to~410 nm was presented from the volatilization and diffusion of alcohol as a model VOC.Additionally,the flow velocity of fluid and the diffusion time were adjusted to explore the underlying mechanism for the dynamic coloration of cholesteric networks.This work is expected to extend the study of PCLCs as a dynamically tunable optofluidic reflector,visually readable sensor,or compact anticounterfeit label in response to organic compounds.

Polymerized cholesteric liquid crystal microdisks generated by centrifugal microfluidics towards tunable laser emissions [Invited]

The method for batch continuous production of polymerized cholesteric liquid crystal(PCLC) microdisks based on centrifugal microfluidics was proposed. The prototype centrifugal microfluidic chip was fabricated by the wetetching technique with a series of ladder-like concentric ring channels whose depths decrease radially. Two types of dye-doped PCLC microdisks with different doping procedures were generated by this method, the tunable lasing properties were characterized, and corresponding potential applications in a micro-cavity laser and optical barcode were demonstrated. The method is also applicable to a broad range of other polymerized materials.