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[Display omitted] • A super-sensitive carbon nanofiber aggregate (SSCNFA) sensor with 0.05% CNFs content has been developed. • The sensor's sensitivity is enhanced due to a well-defined conductive path between CNFs and steel mesh. • SSCNFA can detect forces as low as 0.28 N, making it suitable for stress/strain sensing and damage detection. • The sensor has a wide dynamic range, with any frequency from 1 Hz to 500 kHz available for various applications. A carbon nanofiber aggregate of exceptional sensitivity is developed. Our approach involves the development and utilization of a novel nanobrush structure of carbon nanofiber within the mortar matrix. The high number of nanostructures in the nanobrush, particularly near the electrodes, results in a greater number of nanogaps, leading to a substantial improvement in sensitivity. We are able to detect forces as small as 1 N using this sensor. The carbon nanofiber brush (CNFB) provides a well-defined conductive path for the piezoresistive functioning of the super-sensitive carbon nanofiber aggregate (SSCNFA) with significantly reduced cost. The influence of scanning frequency in impedance is rigorously investigated with alternating current (AC) based on two methods. SSCNFAs are tested in uniaxial compression to determine the highly sensitive face of cube sensor. An SSCNFA (0.05 % CNFs, dense electrodes) and a CNFA (0.5 % CNFs, wide-spaced electrodes) were tested in a sweep-frequency test under parallel compression to compare the super-sensitive performance of the new sensor. The gauge factors at various frequencies were determined. The electrical impedance measured at various frequencies provides versatility to the SSCNFA for stress monitoring. Four fixed-frequency tests were conducted to determine the resolution under uniaxial compression and examine repeatability. [ABSTRACT FROM AUTHOR]

[Display omitted] Magnesium rechargeable batteries are promising candidates for large-scale energy storage due to their -high safety, low material cost, and earthabundant materials. Many redox-active polymers have recently been reported to show excellent cycling stability with decent Mg-storage performance. However, compared to their Li counterparts, these polymers exhibit lower Mg-storage capacity, resulting in a low ratio of materials utilization (η Mg/ η Li) for the same polymer in two electrolyte systems (i.e., Mg vs. Li electrolytes). Herein, we present a sulfur-linked porous polymer, poly(hexaazatrinaphthalene sulfide) (PSHATN), which sets a record for material utilization of 98% among all polymer electrodes and delivers a reversible capacity of 196 mAh g−1 in Mg electrolytes. Based on electrochemical impedance spectroscopy and operando optical microscopy, we discover a strong correlation between specific capacity and degree of electrochemical swelling of polymers in both electrolytes. Importantly, the high ratio (η Mg/ η Li) of PSHATN is ascribed to sufficient electrochemical swelling due to its large pore volume and flexible polymer nature, in contrast to linear polymers and rigid covalent organic frameworks that swell less effectively. This work highlights the critical need for polymer swelling in promoting ion transport in redox polymers for high material utilization and offers important polymer structural design insights for multivalent ion-based energy storage. [ABSTRACT FROM AUTHOR]

Quantifying the interactions of bacteria with external ligands is fundamental to the understanding of pathogenesis, antibiotic resistance, immune evasion, and mechanism of antimicrobial action. Due to inherent cell-to-cell heterogeneity in a microbial population, each bacterium interacts differently with its environment. This large variability is washed out in bulk assays, and there is a need of techniques that can quantify interactions of bacteria with ligands at the single bacterium level. In this work, we present a label-free and real-time plasmonic imaging technique to measure the binding kinetics of ligand interactions with single bacteria, and perform statistical analysis of the heterogeneity. Using the technique, we have studied interactions of antibodies with single Escherichia coli O157:H7 cells and demonstrated a capability of determining the binding kinetic constants of single live bacteria with ligands, and quantify heterogeneity in a microbial population. [ABSTRACT FROM AUTHOR]

Abstract: ZnO and graphene composites (ZnO/GR) were prepared by a simple and repeatable thermal evaporation process, and both the reduction of graphene oxide and the loading of ZnO were achieved. The structural and optical properties were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscope (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) measurements. In the PL spectra, when the mass ratio of graphene to ZnO increased, a series of fluorescence quenching were found, and a regularly blue shift of the ultraviolet (UV) peak were also found, which might be attributed to the Burstein–Moss effect. [Copyright &y& Elsevier]

• Ultra-high-performance carbon nanofiber aggreagate is proposed and developed. • The relationship between electrical response and stress–strain response are obtained. • The influence of scaning frequency and loading orientation are investigated. • The proposed sensor has compressive strength of 138 MPa to fit UHPC strength. Ultra-high-performance concrete (UHPC) is rapidly implemented to build robust, durable, and sustainable structures. This study presents the development of a robust self-sensing sensor with the motivation to monitor structures with high-performance construction material, such as UHPC. The ultra-high-performance carbon nanofiber aggregates (UHPCNFAs) are carbon nanofibers (CNFs) and UHPC-based smart aggregates. The newly developed UHPCNFAs are experimentally investigated in uniaxial compression. Sweep-frequency and fixed-frequency tests are adopted in alternating current measurements for determining the electrical behavior of the UHPCNFAs. UHPCNFAs are compressed in parallel and perpendicular loading orientations to understand the difference in the sensor's electrical sensitivity and mechanical behavior in each case. In addition, the robustness of the UHPCFNA is examined to the point of failure in both orientations. The relationship between stress, strain, and electrical impedance variation is established for eight different frequencies. Furthermore, the UHPCNFAs are compressed at a fixed frequency to verify the repeatable behavior. This paper examines the effect of loading orientations on electrical and mechanical response, robustness, and sensitivity of UHPCNFA in a wide range of frequency spectrum to check its suitability in real-time structural health monitoring. [ABSTRACT FROM AUTHOR]

• A comprehensive report of large-scale field tests for metamaterial-based barriers. • T -Rex mobile shaker at UT Austin is used to generate excitation. • Significant response reduction was observed for cases with metamaterial-based barriers. • Various excitations result in similar results of frequency response function. Seismic isolation systems protect structures and act as decoupling systems with the structure, which aims to uncouple the motion of the structure from incoming waves by reducing the kinetic energy of vibration transferred to structures. This research aims to study a non-invasive vibration isolation system using periodic barriers. A comprehensive field test program is completed to evaluate the wave isolation performance of empty trench and periodic barriers. The precast one-dimensional (1D) periodic barriers are arranged to form one long barrier and one short thick barrier to examine the influence of barrier length and the number of unit cells on the vibration isolation performance. The test program reported in this study is the P0 case (without periodic foundation), which serves as a reference group compared to previous test case P 1 (with periodic barrier and reinforced concrete foundation) and test case P 2 (with a combination of periodic barrier and periodic foundation). The triaxial (T -Rex) shaker truck generates excitation in three axis and the wave form include sine wave, sweep frequency and seismic waves. Each geophone sensor position records the triaxial soil response. The responses of soil along the direction of wave transfer, the normalized responses, and the frequency response function (FRF) are all provided and discussed. Various excitation inputs are comparable. It is found that the excitation directions influence the periodic barrier's effectiveness because of the dominant waveform. When FRF is compared between benchmark case and test cases, the periodic barriers' screening effectiveness can be determined in the attenuation zones. These attenuation zones are expected to be the frequency band gaps of the periodic barrier. When the incoming wave frequency falls in this frequency band gap, the periodic barrier can isolate the vibration propagating towards the protected region. [ABSTRACT FROM AUTHOR]

The Ni atom is difficult to occupy the Ti or Al site in TiAl, it exists in the form of NiTi phase at the grain boundary of TiAl alloy, which is detrimental to the ductility of the TiAl alloy. The Fe and Co atoms preferentially occupy the Al sites and can improve the electronic structures and elastic properties of TiAl, leading to the improvement of the ductility of TiAl alloy. With the addition of 3 at.% Fe and Co, the tested average fracture strain of TiAl alloy increases from 17.3% to 19.1% and 18.0%, respectively. [ABSTRACT FROM AUTHOR]

Nanomaterial additives have been broadly used in cement and concrete-based sensors to measure the stress and strain in the structure. Most of the studies focused on measuring the resistivity of sensors with Direct Current (DC) or relatively low-frequency. In this work, the impedance responses of enhanced Carbon Nano-Fiber Aggregates (CNFAs) at different frequencies are rigorously studied and utilized as a tool for real-time structural health monitoring (SHM). The CNFA impedance measurements at different measurement frequencies provide an extra dimension (frequency dimension) to allow the characterization of different phenomena and multimodal measurements simultaneously. First, a comprehensive physical model is established to understand the frequency responses of the CNFA impedance. Second, COMSOL Multiphysics is used to simulate the frequency responses of the CNFA impedance, which provides more insights into the electric field and current density distribution. The impedance of CNFAs decreased with the increased dosage of carbon nanofibers (CNFs). Third, experimental studies are reported in detail. The electrical impedance variation (EZV) of the CNFA in parallel orientation is 151% higher than that of perpendicular orientation at the frequency of 2612 Hz and uniaxial compression stress of 4.65 MPa. The strain-EZV curve obtained from the response spectrum is linear for frequencies ranging from 98 Hz to 463.9 kHz. The strain-EZV curve for 5625 Hz has a linear fit with the gauge factor of 147.78. At 1000 Hz, the CNFA exhibited a repeatable behavior up to 9.35 MPa and detection limit up to the stress of 18.62 MPa. [ABSTRACT FROM AUTHOR]

Abstract: A series of ZnO and graphene composites (ZnO/GRs) was synthesized by a simple and nontoxic hydrothermal reaction route. The TEM, AFM, FTIR, Raman and current–voltage (I–V) results demonstrated that the ZnO particles were coated by the graphene sheets, confirming the formation of ZnO/GRs composites. During the photocatalytic test, in comparison with ZnO and P25, the ZnO/GRs exhibited enhanced photocatalytic performance for degradation of methylene blue (MB) dye since the graphene sheets could prevent the photoinduced hole–electron pairs of ZnO from recombination by transferring the photoinduced electron to the MB. When the mass ratio of ZnO to graphene was 50:1, the ZnO/GR showed the best photocatalytic performance. Moreover the photocorrosion of ZnO was inhibited to a large extent, which could be attributed to the formation of ZnO and graphene composite. [Copyright &y& Elsevier]