Correction: Ji et al. Mesoporous Cobalt Oxide (CoOx) Nanowires with Different Aspect Ratios for High Performance Hybrid Supercapacitors. Nanomaterials 2023, 13, 749.

There was an error in the original publication [...].

Integrating street view images and deep learning to explore the association between human perceptions of the built environment and cardiovascular disease in older adults.

Understanding how built environment attributes affect health remains important. While many studies have explored the objective characteristics of built environments that affect health outcomes, few have examined the role of human perceptions of built environments on physical health. Baidu Street View images and computer vision technological advances have helped researchers overcome the constraints of traditional methods of measuring human perceptions (e.g., these methods are laborious, time-consuming, and costly), allowing for large-scale measurements of human perceptions. This study estimated human perceptions of the built environment (e.g., beauty, boredom, depression, safety, vitality, and wealth) by adopting Baidu Street View images and deep learning algorithms. Negative binomial regression models were employed to analyze the relationship between human perceptions and cardiovascular disease in older adults (e.g., ischemic heart disease and cerebrovascular disease). The results indicated that wealth perception is negatively related to the risk of cardiovascular disease. However, depression and vitality perceptions are positively associated with the risk of cardiovascular disease. Furthermore, we found no relationship between beauty, boredom, safety perceptions, and the risk of cardiovascular disease. Our findings highlight the importance of human perceptions in the development of healthy city planning and facilitate a comprehensive understanding of the relationship between built environment characteristics and health outcomes in older adults. They also demonstrate that street view images have the potential to provide insights into this complicated issue, assisting in the formulation of refined interventions and health policies.

Position-Induced Controllable Growth of Vertically Oriented Graphene Using Plasma-Enhanced Chemical Vapor Deposition.

Because the morphology of vertically oriented graphene (VG) synthesized by the plasma-enhanced chemical vapor deposition process determines the application performance of VG, morphology control is always an important part of the research. A concise correspondence between plasma and the morphology of VG is the key to investigating the morphology control of VG, which is still under research. In this study, a simple but effective parameter, position, is used to grow VG, by which the continuous morphology evolution of VG is realized. As a result, the morphology of VGs varies from a porous structure to a "wall-like" structure, thus leading to a continuous change in its hydrophobicity and thermal emissivity. An ultrahigh emissivity of 0.999 with superhydrophobicity is obtained among these VGs, showing great potential in the area of the black body and infrared thermometer. Finally, the states of active particles in plasma depending on the positions are diagnosed to investigate their relations with the morphology of VGs.

Fast-response photothermal bilayer actuator based on poly(N-isopropylacrylamide)-graphene oxide-hydroxyethyl methacrylate/polydimethylsiloxane.

Demands for highly deformable and responsive intelligent actuators are increasing rapidly. Herein, a photothermal bilayer actuator consisting of a photothermal-responsive composite hydrogel layer and a polydimethylsiloxane (PDMS) layer is presented. The photothermal-responsive composite hydrogel is prepared by compositing hydroxyethyl methacrylate (HEMA) and the photothermal material graphene oxide (GO) with the thermal-responsive hydrogel poly(N-isopropylacrylamide) (PNIPAM). The HEMA improves the transport efficiency of water molecules inside the hydrogel network, eliciting a fast response and large deformation, facilitating greater bending behavior of the bilayer actuator, and improving the mechanical and tensile properties of the hydrogel. Moreover, GO enhances the mechanical properties and the photothermal conversion efficiency of the hydrogel in the thermal environment. This photothermal bilayer actuator can be driven under various conditions, such as hot solution, simulated sunlight, and laser, and can achieve large bending deformation with desirable tensile properties, broadening the application conditions for bilayer actuators, such as artificial muscles, bionic actuators, and soft robotics.

Equal-intensity beam splitter realization by wire grid polarizers for passive laser speckle reduction.

A method to realize an equal-intensity beam splitter (EIBS) using wire grid polarizers (WGPs) is proposed. The EIBS consists of WGPs with predetermined orientations and high-reflectivity mirrors. We demonstrated the generation of three laser sub-beams (LSBs) with equivalent intensities using EIBS. The three LSBs were incoherent by introducing optical path differences larger than the laser coherence length. The LSBs were used to reduce speckle passively, where the objective speckle contrast was reduced from 0.82 to 0.5 when all three LSBs were used. The feasibility of EIBS in speckle reduction was studied using a simplified laser projection system. The structure of the EIBS implemented by WGPs is simpler than EIBSs obtained by other methods.

Synthesizing Metal Oxide Semiconductors on Doped Si/SiO2 Flexible Fiber Substrates for Wearable Gas Sensing.

Traditional metal oxide semiconductor (MOS) gas sensors have limited applications in wearable devices owing to their inflexibility and high-power consumption by substantial heat loss. To overcome these limitations, we prepared doped Si/SiO2 flexible fibers by a thermal drawing method as substrates to fabricate MOS gas sensors. A methane (CH4) gas sensor was demonstrated by subsequently in situ synthesizing Co-doped ZnO nanorods on the fiber surface. The doped Si core acted as the heating source through Joule heating, which conducted heat to the sensing material with reduced heat loss; the SiO2 cladding was an insulating substrate. The gas sensor was integrated into a miner cloth as a wearable device, and the concentration change of CH4 was monitored in real time through different colored light-emitting diodes. Our study demonstrated the feasibility of using doped Si/SiO2 fibers as the substrates to fabricate wearable MOS gas sensors, where the sensors have substantial advantages over tradition sensors in flexibility, heat utilization, etc.

Pressure Sensor Based on a Lumpily Pyramidal Vertical Graphene Film with a Broad Sensing Range and High Sensitivity.

Wearable sensors are vital for the development of electronic skins to improve health monitoring, robotic tactile sensing, and artificial intelligence. Active materials and the construction of microstructures in the sensitive layer are the dominating approaches to improve the performance of pressure sensors. However, it is still a challenge to simultaneously achieve a sensor with a high sensitivity and a wide detection range. In this work, using three-dimensional (3D) vertical graphene (VG) as an active material, in combination with micropyramid arrays and lumpy holders, the stress concentration effects are generated in nano-, micro-, and macroscales. Therefore, the lumpily pyramidal VG film-based pressure sensor (LPV sensor) achieves an ultrahigh sensitivity (131.36 kPa-1) and a wide response range (0.1-100 kPa). Finite element analysis demonstrates that the stress concentration effects are enhanced by the micropyramid arrays and lumpy structures in micro- and macroscales, respectively. Finally, the LPV pressure sensors are tested in practical applications, including wearable health monitoring and force feedback of robotic tactile sensing.

Highly Sensitive and Flexible Capacitive Pressure Sensors Based on Vertical Graphene and Micro-Pyramidal Dielectric Layer.

Many practical applications require flexible high-sensitivity pressure sensors. However, such sensors are difficult to achieve using conventional materials. Engineering the morphology of the electrodes and the topography of the dielectrics has been demonstrated to be effective in boosting the sensing performance of capacitive pressure sensors. In this study, a flexible capacitive pressure sensor with high sensitivity was fabricated by using three-dimensional vertical graphene (VG) as the electrode and micro-pyramidal polydimethylsiloxane (PDMS) as the dielectric layer. The engineering of the VG morphology, size, and interval of the micro-pyramids in the PDMS dielectric layer significantly boosted the sensor sensitivity. As a result, the sensors demonstrated an exceptional sensitivity of up to 6.04 kPa-1 in the pressure range of 0-1 kPa, and 0.69 kPa-1 under 1-10 kPa. Finite element analysis revealed that the micro-pyramid structure in the dielectric layer generated a significant deformation effect under pressure, thereby ameliorating the sensing properties. Finally, the sensor was used to monitor finger joint movement, knee motion, facial expression, and pressure distribution. The results indicate that the sensor exhibits great potential in various applications, including human motion detection and human-machine interaction.

Mesoporous Cobalt Oxide (CoOx) Nanowires with Different Aspect Ratios for High Performance Hybrid Supercapacitors.

Cobalt oxide (CoOx) nanowires have been broadly explored as advanced pseudocapacitive materials owing to their impressive theoretical gravimetric capacity. However, the traditional method of compositing with conductive nanoparticles to improve their poor conductivity will unpredictably lead to a decrease in actual capacity. The amelioration of the aspect ratio of the CoOx nanowires may affect the pathway of electron conduction and ion diffusion, thereby improving the electrochemical performances. Here, CoOx nanowires with various aspect ratios were synthesized by controlling hydrothermal temperature, and the CoOx electrodes achieve a high gravimetric specific capacity (1424.8 C g-1) and rate performance (38% retention at 100 A g-1 compared to 1 A g-1). Hybrid supercapacitors (HSCs) based on activated carbon anode reach an exceptional specific energy of 61.8 Wh kg-1 and excellent cyclic performance (92.72% retention, 5000 cycles at 5 A g-1). The CoOx nanowires exhibit great promise as a favorable cathode material in the field of high-performance supercapacitors (SCs).

Post COVID-19 pandemic recovery of intracity human mobility in Wuhan: Spatiotemporal characteristic and driving mechanism.

After successfully inhibiting the first wave of COVID-19 transmission through a city lockdown, Wuhan implemented a series of policies to gradually lift restrictions and restore daily activities. Existing studies mainly focus on the intercity recovery under a macroscopic view. How does the intracity mobility return to normal? Is the recovery process consistent among different subareas, and what factor affects the post-pandemic recovery? To answer these questions, we sorted out policies adopted during the Wuhan resumption, and collected the long-time mobility big data in 1105 traffic analysis zones (TAZs) to construct an observation matrix (A). We then used the nonnegative matrix factorization (NMF) method to approximate A as the product of two condensed matrices (WH). The column vectors of W matrix were visualized as five typical recovery curves to reveal the temporal change. The row vectors of H matrix were visualized to identify the spatial distribution of each recovery type, and were analyzed with variables of population, GDP, land use, and key facility to explain the recovery driving mechanisms. We found that the "staggered time" policies implemented in Wuhan effectively staggered the peak mobility of several recovery types ("staggered peak"). Besides, different TAZs had heterogeneous response intensities to these policies ("staggered area") which were closely related to land uses and key facilities. The creative policies taken by Wuhan highlight the wisdom of public health crisis management, and could provide an empirical reference for the adjustment of post-pandemic intervention measures in other cities.

Vertical Graphene Canal Mesh for Strain Sensing with a Supereminent Resolution.

The development of microstrain sensors offers significant prospects in diverse applications, such as microrobots, intelligent human-computer interaction, health monitoring, and medical rehabilitation. Among strain sensor materials, vertical graphene (VG) has demonstrated considerable potential as a resistive material; however, VG-based strain sensors with high resolution are yet to be developed. In addition, the detection mechanism of VG has not been extensively investigated. Herein, we developed a VG canal mesh (VGCM) to fabricate a flexible strain sensor for ultralow strain sensing, achieving an accurate response to strains as low as 0.1‰ within a total strain range of 0%-4%. The detection of such low strains is due to the rigorous structural design and strain concentration effect of the three-dimensional micronano structure of the VGCM. Through experimental results and theoretical simulation, the evolution of microcracks in VG and the sensing mechanism of VG and VGCM are elaborated, and the unique advantages of VGCM are revealed. Finally, the VGCM-based strain sensors are proposed as portable breathing test equipment for rapid breathing detection.

Porous Carbon Boosted Non-Enzymatic Glutamate Detection with Ultra-High Sensitivity in Broad Range Using Cu Ions.

A non-enzymatic electrochemical sensor, based on the electrode of a chitosan-derived carbon foam, has been successfully developed for the detection of glutamate. Attributed to the chelation of Cu ions and glutamate molecules, the glutamate could be detected in an amperometric way by means of the redox reactions of chelation compounds, which outperform the traditional enzymatic sensors. Moreover, due to the large electroactive surface area and effective electron transportation of the porous carbon foam, a remarkable electrochemical sensitivity up to 1.9 × 104 µA/mM∙cm2 and a broad-spectrum detection range from nM to mM scale have been achieved, which is two-orders of magnitude higher and one magnitude broader than the best reported values thus far. Furthermore, our reported glutamate detection system also demonstrates a desirable anti-interference ability as well as a durable stability. The experimental revelations show that the Cu ions chelation-assisted electrochemical sensor with carbon foam electrode has significant potential for an easy fabricating, enzyme-free, broad-spectrum, sensitive, anti-interfering, and stable glutamate-sensing platform.

Equal-intensity beam splitter fabricated by segmented half-wave plate for passive laser speckle reduction.

An equal-intensity beam splitter (EIBS) for passive laser speckle reduction is reported. The EIBS consists of a segmented half-wave plate (SHWP) with the designed orientation of the fast axis of each segment, a polarization beam splitter, and a mirror. The SHWP is fabricated using patterned photoalignment material and liquid crystal polymer. Ten laser sub-beams are generated by the twenty-one-pixelated EIBS, where the largest intensity ratio among them is 7.6. Laser temporal and spatial coherences are destroyed because of the optical path delays among the laser sub-beams. The EIBS is used to reduce laser speckle passively, and objective speckle contrast is reduced from 0.82 to 0.33 when all 10 laser sub-beams are used.

Oxygen-Assisted Trimming Growth of Ultrahigh Vertical Graphene Films in a PECVD Process for Superior Energy Storage.

Combining the advantages of a three-dimensional structure with intrinsic properties of graphene, vertical graphene (VG) synthesized by the plasma-enhanced chemical vapor deposition (PECVD) process has shown great promise to be applied to energy-storage electrodes. However, the practical application of the VG electrodes suffers from the limited height, which is mostly in a scale of few hundreds of nanometers, as shown in the previous studies. The reason for the unacceptable thin VG film deposition is believed to be the height saturation, stemming from the inevitable confluence of the VG flakes along with the deposition time. In this study, we developed an oxygen-assisted "trimming" process to eliminate the overfrondent graphene nanosheets thereby surmounting the saturation of the VG thickness during growth. In this approach, the height of the VGs reaches as high as 80 µm. Tested as supercapacitor electrodes, a desirable capacitance of 241.35 mF cm-2 is obtained by the VG films, indicating the superior electrochemical properties and the potential for applications in energy storage. It is worth noting, this thickness is by no means the maximum that can be achieved with our synthesis technique and higher capacitance can be achieved by conducting the circulating deposition-correction process in our work.

Micro-refractive optical elements fabricated by multi-exposure lithography for laser speckle reduction.

Laser speckle reduction with a macro refractive optical element (mROE) is restricted by the limited entrance facet size of light pipe. Here, we have fabricated a micro-ROE (µROE) that incorporates three-dimensional micro-optical structures. The µROE with 2 × 2 duplicated multi-level cells is made of SU-8 photoresist with the help of multi-exposure lithography process. When the µROE works together with the mROE, objective speckle contrast is reduced to 0.2, where the light source is a low-coherence multimode laser diode. In principle, more speckle reduction can be obtained by fabricating µROEs with more cells and larger height differences among the cells.

Influence of Spatial Inhomogeneity of Detector Temporal Responses on the Spectral Fidelity in Continuous Wave Cavity Ringdown Spectroscopy.

Due to their advantages of having a wide bandwidth, low cost, and being easy to obtain, traditional photodetectors (PDs) are being widely applied in measurements of transient signals. The spatial inhomogeneity of such PD temporal responses was measured directly to account for the PD spatial effect of decay rate due to poor alignment in continuous wave cavity ringdown spectroscopy (CW-CRDS) experiments. Based on the measurements of three PDs (i.e., model 1611 (Newport), model 1811 (Newport), and model PDA10CF-EC (Thorlabs)), all the temporal responses followed a tendency of declining first and then rising, and steady platforms existed for the last two PDs. Moreover, as we expected, the closer the PD center was, the faster the response. On the other hand, the initial shut-off amplitude generally reached a larger value for a faster temporal response. As a result, the spatial effect can strongly influence the spectral line shape and value, which will introduce more errors into the precise measurements of spectral parameters using the CRDS technique if this effect is not considered. The defined effective detection area (EDA) of the PDs, which was close to the active area given by manufacturers, was the key parameter that should be paid more attention by researchers. Therefore, the PD should be aligned perfectly to make sure that the EDA covers the laser spot completely.

Experimental Investigation on Vertically Oriented Graphene Grown in a Plasma-Enhanced Chemical Vapor Deposition Process.

Vertically oriented graphene (VG) with three-dimensional architecture has been proved to exhibit unique properties, and its particular morphology has been realized by researchers to be crucial for its performance in practical applications. In this study, we investigated the morphology evolution of VG films synthesized by the plasma-enhanced chemical vapor deposition process, including porous graphene film, graphene wall, and graphene forest. This study reveals that the morphology of VG is controlled by a combination of the deposition and etching effects and tailored by the growth conditions, such as plasma source power and growth time and temperature. The plasma source power relates to the number of branches of VG, and the growth temperature relates to the thickness of each VG flake, whereas the growth time determines the height of VG. Finally, the electrochemical properties of VG films along with morphology evolution are investigated by fabricating as VG-based supercapacitor electrodes.

Weak-scattering static diffuser by fast pumping dispersed-nanoparticles in a long distance using microfluidic flows for efficient laser speckle reduction.

Changing diffusers are most commonly used for laser speckle reduction. Here, a weak-scattering static diffuser (WSSD) is proposed and demonstrated by fast pumping poly(methyl methacrylate) nanoparticles in a long distance using microfluidic flow. Experimental results show that this proof-of-concept device can effectively reduce speckle, where the lowest speckle contrast ratio is 0.04. Comparing with vibrating/rotating diffusers driven by mechanical motors for speckle reduction, the WSSD is static. Moreover, the WSSD can suppress speckle with weaker light scatterings (scattering angle equals to 5.8° at the lowest speckle contrast ratio value), making it superior to vibrating/rotating diffusers driven by micro actuators. Because of these promising advantages, the WSSD has prospects of wide range of applications, such as in laser projection displays.

Combination of micro-scanning mirrors and multi-mode fibers for speckle reduction in high lumen laser projector applications.

In high lumen laser projectors, it is required to use laser diodes coupled to multi-mode fibers (MMFs) to obtain a high power illumination module. In this paper, we have fabricated an electromagnetic micro-scanning mirror (EM-MSM), and we have firstly demonstrated a speckle reduction method by the combination of the EM-MSM and the MMF. With the help of a condenser lens, laser beams modulated and reflected from the EM-MSM are coupled into the MMF within its acceptance angle. Because the fast scanning behavior of the EM-MSM results in the phase modulation and mode coupling among the MMF guided modes, the light intensity field distributions at the exit aperture of the MMF are changing. During the charge-coupled device (CCD) integration time, the random speckle patterns are integrated and homogenized by the CCD camera, and hence speckle is reduced. By driving the EM-MSM in raster scan, the lowest compound speckle contrast ratio at 0.0794 is obtained, where the EM-MSM half scanning angles are 0.4 ° and the optical power loss is lower than 4.5%. The demonstrated technique is compact and can endure the high power of the laser module; thus, it has a promising potential in high lumen laser projector applications.

Speckle contrast for superposed speckle patterns created by rotating the orientation of laser polarization.

For a rough diffuser that fully depolarizes a linearly polarized laser, the speckle contrast of a fully developed speckle image can be reduced from 1 to 0.5 by polarization diversity. This reduction is achieved by rotating an x-polarized laser to the y-polarized orientation to form four independent speckle patterns with equal intensities during the detector exposure time. For the case of arbitrary rotation of the polarization, we derived a generalized speckle contrast formula for the superposed speckle patterns. This formula completes the theory of speckle contrast for the sum of correlated speckle intensities as it relates to polarization diversity.