Homogeneity Enhancement of Mixtures Containing Epoxy Polymer and 100% Reclaimed Asphalt Pavement.

The utilization of reclaimed asphalt pavement (RAP) could reduce the cost of pavements containing epoxy polymer (EP) materials. This study was aimed at improving the homogeneity of an EP-reclaimed asphalt mixtures (ERAMs) at both the micro- and meso-scale to provide a reference for an ERAM production process. At the microscale, nanoindentation tests were conducted to characterize the diffusion between the EP and aged asphalt mastic. At the mesoscale, computerized tomography (CT) X-ray scanning and MATLAB analysis were employed to investigate the distribution of the aggregate within the ERAM. The results revealed that mixing temperature played a significant role in the diffusion and distribution between the EP and the aged asphalt mastic, thus impacting the mechanical properties of the material. Heating at 180 °C (the recommended mixing temperature of EP) resulted in a wider blending zone between the EP and the aged asphalt mastic compared to heating at 160 °C (the usual mixing temperature of ordinary reclaimed asphalt mixtures). The overall dispersion of the aggregate in the ERAM exhibited greater homogeneity in the vertical direction than in the horizontal direction. Adjusting the gradation of the RAP was found to be effective in reducing horizontal variability in the distribution of the coarse aggregate, fine aggregate, and air voids in the ERAM. Adjusting the RAP gradation further enhanced the vertical homogeneity in the distribution of the fine aggregate, while its impact on the vertical distribution of the coarse aggregate was minimal. Short-term aging led to increased variability in the distribution of the coarse aggregate, fine aggregate, and air voids within the ERAM. However, adjusting the gradation was effective in mitigating the adverse effects of short-term aging on both horizontal and vertical homogeneity in the aggregate distribution.

A Symmetric-Actuating Linear Piezoceramic Ultrasonic Motor Capable of Producing a Scissoring Effect.

Conventionally, to produce a linear motion, one motor's stator is employed to drive one runner moving forward or backward. So far, there is almost no report of one electromechanical motor or piezoelectric ultrasonic motor that can directly generate two symmetrical linear motions, while this function is desired for precise scissoring and grasping in the minimally invasive surgery field. Herein, we report a brand-new symmetric-actuating linear piezoceramic ultrasonic motor capable of generating symmetrical linear motions of two outputs directly without additional mechanical transmission mechanisms. The key component of the motor is an (2 × 3) arrayed piezoceramic bar stator operating in the coupled resonant mode of the first longitudinal (L1) and third bending (B3) modes, leading to symmetric elliptical vibration trajectories at its two ends. A pair of microsurgical scissors is used as the end-effector, demonstrating a very promising future for high-precision microsurgical operations. The sliders of the prototype show the following features: (a) symmetrical, fast relative moving velocity (~1 m/s) outward or inward simultaneously; (b) high step resolution (40 nm); and (c) high power density (405.4 mW/cm3) and high efficiency (22.1%) that are double those of typical piezoceramic ultrasonic motors, indicating the full capacity of symmetric-actuating linear piezoceramic ultrasonic motor working in symmetric operation principle. This work also has enlightening significance for future symmetric-actuating device designs.

Double [4]Helicene-like Naphthobisbenzothiophene Diimides and Their Thienyl-S,S-dioxidized Derivatives with Attractive Solid-State Fluorescence and High Electron Affinity.

A series of double [4]helicene-like naphthobisbenzothiophene diimides and their thienyl-S,S-dioxidized derivatives are synthesized via MoCl5-catalyzed cyclization and m-CPBA-mediated oxidation reactions. The functional five-membered ring diimides show a helicene-like geometry, strong solid-state fluorescence, and deep LUMO of -4.37 eV.

Detecting concealed information using functional near-infrared spectroscopy (fNIRS) combined with skin conductance, heart rate, and behavioral measures.

In this study, brain imaging data from functional near-infrared spectroscopy (fNIRS) associated with skin conductance response (SCR), heart rate (HR), and reaction time (RT) were combined to determine if the combination of these indicators could improve the efficiency of deception detection in concealed information test (CIT). During the CIT, participants were presented with a series of names and cities that served as target, probe, or irrelevant stimuli. In the guilty group, the probe stimuli were the participants' own names and hometown cities, and they were asked to deny this information. Our results revealed that probe items were associated with longer RT, larger SCR, slower HR, and higher oxyhemoglobin (HbO) concentration changes in the inferior prefrontal gyrus (IFG), middle frontal gyrus (MFG), and the superior frontal gyrus (SFG) compared with irrelevant items for participants in the guilty group but not in the innocent group. Furthermore, our results suggested that the combination of RT, SCR, HR, and fNIRS indicators could improve the deception detection efficiency to a very high area under the ROC curve (0.94) compared with any of the single indicators (0.74-0.89). The improved deception detection efficiency might be attributed to the reduction of random error and the diversiform underlying the psychophysiological mechanisms reflected by each indicator. These findings demonstrate a feasible way to improve the deception detection efficiency by using combined multiple indicators.

Designing Artificial Vibration Modes of Piezoelectric Devices Using Programmable, 3D Ordered Structure with Piezoceramic Strain Units.

Piezoelectric ceramic devices, which utilize multifarious vibration modes to realize electromechanical coupling and energy conversions, are extensively used in high-technological fields. However, the excitation of basic modes is mainly subjected to natural eigenfrequency of ceramic devices, which is related to the structure and material parameters. Herein, inspired by metamaterial theory, a programmable, 3D ordered structure with piezoceramic strain units (3D OSPSU) is developed to artificially generate basic modes in a broad frequency band other than only in narrow eigenfrequency. A (2 × 2 × 2) arrayed, co-fired, multilayer 3D OSPSU is painstakingly designed and fabricated for generating basic modes, such as flexural, extension, shear, torsion, and even coupled modes at nonresonance. To validate the 3D OSPSU method, a five-degree-of-freedom micro-nano actuating platform based on only one co-fired multilayer ceramic is constructed. The proposed methodology provides a new paradigm for creating extraordinary material properties of piezoelectric ceramics and will inspire brand-new piezoelectric device designs.

Cross-Functional Test to Explore the Determination Method of Meso-Parameters in the Discrete Element Model of Asphalt Mixtures.

In order to obtain more accurate parameters required for the simulation of asphalt mixtures in the discrete element method (DEM), this study carried out a series of cross-functional asphalt mixture experiments to obtain the DEM simulation meso-parameters. By comparing the results of simulation and actual experiments, a method to obtain the meso-parameters of the DEM simulation was proposed. In this method, the numerical aggregate profile was obtained by X-ray CT scanning and the 3D aggregate model was reconstructed in MIMICS. The linear contact parameters of the aggregate and the Burgers model parameters of the asphalt mastic were obtained by nanoindentation technology. The parameters of the parallel bonding model between the aggregate and mastic were determined by the macroscopic tensile adhesion test and shear bond test. The results showed that the meso-parameters obtained by the macroscopic experiment provide a basis for the calibration of DEM parameters to a certain extent. The trends in simulation results are similar to the macro test results. Therefore, the newly proposed method is feasible.

Designing Ordered Structure with Piezoceramic Actuation Units (OSPAU) for Generating Continual Nanostep Motion.

Continual precision actuations with nanoscale resolution over large ranges have extensive requirements in advanced intelligent manufacturing and precise surgical robots. To produce continual nanostep motion, conventionally, multiple pairs of piezo-actuators are employed to operate in inchworm principle under complex three- or four-phase timing signal drive. Inspired by the idea of ordered structures with functional units, a much simpler nanostep piezoelectric actuator consisting of (2 × 2) arrayed, cofired multilayer piezoceramic actuation units is developed, which operates in an artificially generated quasi shear mode (AGQSM) that is missing in natural piezoelectric ceramics. Under only one-phase square-wave voltage drive, the actuator can produce a stable, continual nanostep motion in two ways at nonresonant frequencies, and the obtained minimum step displacement is as low as 7 nm in open control, indicating its potential application as a precise finger or knife actuator in surgical robots. This work is of great guiding significance for future actuator designs using the methodology of ordered structure with piezoceramic actuation units and AGQSM.

Chemical and microscopic investigation of co-pyrolysis of crumb tire rubber with waste cooking oil at mild temperature.

Approximate rubber/bitumen homogeneous system formed by desulfurization and degradation of crumb tire rubber in bitumen under high temperature is beneficial to enhance the storage stability of rubberized bitumen. However, the main problems during the processing of desulfurized and degraded rubberized bitumen are aging caused by volatilization of light components, and burning or explosion due to the direct utilization of low flash point bitumen. Therefore, waste cooking oil was proposed as a safer medium to desulfurize and degrade crumb rubber prior to production of rubberized bitumen. This study focused on the feasibility and effectiveness of the application of waste cooking oil in desulfurizing and degrading rubber particles through co-pyrolysis of them at mild temperature (240-280 °C). Chemical and microscopic analyses were performed to investigate the structural changes of vulcanized rubber. Results showed that solubility of rubber powder reached above 60 wt% after pyrolysis in waste cooking oil, which increased with higher temperatures and more of oil, while increased to a maximum at 2 h and then decreased with the extension of time. The rubber hydrocarbon content decreased greatly, and dramatic reduction of carbon, hydrogen and sulfur elements happened according to component and elemental analyses. The surface of pyrolysis product was even and smooth without obvious rubber particles. The grooves and cavities of rubber residues in scanning electron microscopy micrographs proved that shedding of degraded polymer molecules occurred. Fourier transform infrared spectra revealed that breakage of carbon-sulfur, carbon=carbon and sulfur=oxygen bonds took place during pyrolysis, with appearance of natural rubber characteristic peak.