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Dynamics of photoinduced species, as a key parameter for nanomaterials plays a significantly role in the performance of optoelectronic devices. In this work, the origin of broadband optical response for the emerging Ti3C2Tx MXene is revealed by transient spectroscopic analysis. From ultraviolet to infrared, the steady-state and transient optical responses present wavelength-related features. The carrier lifetime is found to change from femtosecond to nanosecond time scale dominated by various photoinduced species, i.e., carrier and surface plasmon. The unique optoelectronic character enables photodetection. This fundamental study on carrier, plasmon dynamics, and application in photodetection is helpful for exploring MXene-based optoelectronic devices.

Unlike traditional two-dimensional layered materials, tellurium (Te) shows its one-dimensional van der Waals structure and triggers intensive researches. Through a density functional theory coupled with the nonequilibrium Green’s function calculation, we found that bilayer tellurene has a broad photoelectric response over the range from the visible to the near-infrared region. Besides, bilayer tellurene photodetector presents an ultra-strong anisotropic photo-responsivity and an ultra-high extinction ratio (~2812 at the photon energy of 3.4 eV) because of its non-layer/chain structure, which is superior to the antimonene (~145) and phosphorene/blue phosphorene bilayers (~240). Time-domain first principle study further reveals that the ultra-strong anisotropy comes from the transition of Te 5p bonding orbitals along or perpendicular to the chain directions. With these excellent optoelectronic merits, bilayer tellurene may become a promising candidate for next-generation photoelectronic devices.

Old landslides in the Loess Plateau, Northwest China usually occurred over a relatively long period, and their sizes are usually smaller compared to old landslides in the alpine valley areas of Sichuan, Yunnan, and Southeast Tibet. These landslide areas may have been changed either partially or greatly, and they are usually covered with vegetation and similar to their surrounding environment. Therefore, it is a great challenge to detect them using high-resolution remote sensing images with only orthophoto view. This paper proposes the optimal-view and multi-view strategic hybrid deep learning (OMV-HDL) method for old loess landslide detection. First, the optimal-view dataset in the Yan'an area (YA-OP) was established to solve the problem of insufficient optical features in orthophoto images. Second, in order to make the process of interpretation more labor-saving, the optimal-view and multi-view (OMV) strategy was proposed. Third, hybrid deep learning with weighted boxes fusion (HDL-WBF) was proposed to detect old loess landslides effectively. The experimental results with the constructed optimal-view dataset and multi-view data show that the proposed method has excellent performance among the compared methods—the F1 score and AP (mean) of the proposed method were improved by about 30% compared with the single detection model using traditional orthophoto-view data—and that it has good detection performance on multi-view data with the recall of 81.4%. [ABSTRACT FROM AUTHOR]

The recovery of gold from water is an important research area. Recent reports have highlighted the ultrahigh capacity and selective extraction of gold from electronic waste using reduced graphene oxide (rGO). Here, we made a further attempt with the thermal rGO membranes and found that the thermal rGO membranes also had a similarly high adsorption efficiency (1.79 g gold per gram of rGO membranes at 1000 ppm). Furthermore, we paid special attention to the detailed selectivity between Au3+ and other ions by rGO membranes. The maximum adsorption capacity for Au3+ ions was about 16 times that of Cu2+ ions and 10 times that of Fe3+ ions in a mixture solution with equal proportions of Au3+/Cu2+ and Au3+/Fe3+. In a mixed-ion solution containing Au3+:Cu2+:Na+:Fe3+:Mg2+ of printed circuit board (PCB), the mass of Au3+:Cu2+:Na+:Fe3+:Mg2+ in rGO membranes is four orders of magnitude higher than the initial mass ratio. A theoretical analysis indicates that this selectivity may be attributed to the difference in the adsorption energy between the metal ions and the rGO membrane. The results are conducive to the usage of rGO membranes as adsorbents for Au capture from secondary metal resources in the industrial sector. [ABSTRACT FROM AUTHOR]

Transgender and nonbinary (TNB) individuals are at increased risk for depression, making it important to understand the factors that may contribute to or attenuate this disparity. Community connectedness is one such factor, but prior research regarding its effect on depression has been mixed. It is possible that these mixed findings may be because community connectedness leads to multiple types of self-focused attention (i.e., gender reflection, gender rumination, and preoccupation with others' perceptions) which then have opposing effects on depression. To explore this possibility, the current study sought to test a mediation model in which the three types of self-focused attention would mediate the relationship between community connectedness and depression. Cross-sectional data were collected using online surveys with 309 TNB young adults aged 18–30 years old. As hypothesized, preoccupation with others' perceptions was a significant mediator explaining 35.85% of the variance in depression. Contrary to expectations, gender reflection and gender rumination were not significant mediators. However, community connectedness significantly predicted greater gender reflection, while gender rumination predicted greater depression. The present results indicate that different types of self-focused attention have differing effects on depression in this population, suggesting that clinicians working with TNB young adults should target the ways that these clients think about their gender identity. Additionally, connection to the TNB community can have multiple effects on thought processes, and efforts should be made to maximize the benefits while minimizing the costs. Future research should test these relationships using longitudinal designs and at different ages, as well as assess whether aspects of the community connectedness itself (e.g., co-rumination in TNB spaces, online vs. in-person connection) may have different effects. [ABSTRACT FROM AUTHOR]

Landslides pose a greater potential risk to the Sichuan-Tibet Transportation Project, and extensive landslide inventory and mapping are essential to prevent and control geological hazards along the Sichuan-Tibet Transportation Corridor (STTC). Recently proposed landslide detection methods mainly focused on new landslides with high vegetation. In addition, there are still challenges in automatic detection of old landslides using optical images. In this paper, two methods, namely mask region-based convolutional neural networks (Mask R-CNN) and transfer learning Mask R-CNN (TL-Mask R-CNN), are presented for detecting and segmenting new and old landslides, respectively. An optical remote sensing dataset for landslide recognition along the Sichuan-Tibet Transportation Corridor (LRSTTC) is constructed as an evaluation benchmark. Our experimental results show that the recall rate and F1-score of the proposed method for new landslide detection can reach 78.47% and 79.80%, respectively. Transfer learning is adopted to detect old landslides, and our experimental results show that evaluation indices can be further improved by about 10%. Furthermore, TL-Mask R-CNN has been applied to identify ice avalanches based on the characteristics of landslides. It appears that our proposed methods can detect and segment landslides effectively along the STTC with the constructed LRSTTC dataset, which is essential for studying and preventing landslide hazards in mountainous areas. [ABSTRACT FROM AUTHOR]

Considering current problems in the identifying, locating, and supervising of construction waste, it is difficult to achieve real-time target judgement and identification in the short term. This study proposes a deep learning-based construction waste identification and classification system, named IUNet-IF, developed using unmanned aerial vehicle (UAV) images. High-resolution UAV aerial images were used to establish a sample database and train U-Net models. The U-Net model, which exhibited the highest overall performance and identification accuracy, was enhanced to develop an IUNet model. Subsequently, the texture and colour features of UAV images were extracted and input to the IUNet model to build a novel IUNet-IF model. The proposed method uses the optimal model and an input combination of texture features, colour features, and original images, which improves the segmentation results compared to those when only the original image is used. The experimental results indicate that the system can achieve a maximum pixel accuracy index, mean intersection over union (mIoU), and mean pixel accuracy (MPA) of 98.98%, 93.78%, and 97.26%, respectively. These results verify the feasibility of extracting construction waste covered by a dust-proof net from UAV remote sensing images and can provide reference information for the automatic extraction of construction waste. [ABSTRACT FROM AUTHOR]

The ion-enrichment inside carbon nanotubes (CNTs) offers the possibility of applications in water purification, ion batteries, memory devices, supercapacitors, field emission and functional hybrid nanostructures. However, the low filling capacity of CNTs in salt solutions due to end caps and blockages remains a barrier to the practical use of such applications. In this study, we fabricated ultra-short CNTs that were free from end caps and blockages using ball milling and acid pickling. We then compared their ion-enrichment capacity with that of long CNTs. The results showed that the ion-enrichment capacity of ultra-short CNTs was much higher than that of long CNTs. Furthermore, a broad range of ions could be enriched in the ultra-short CNTs including alkali-metal ions (e.g., K+), alkaline-earth-metal ions (e.g., Ca2+) and heavy-metal ions (e.g., Pb2+). The ultra-short CNTs were much more unobstructed than the raw long CNTs, which was due to the increased orifice number per unit mass of CNTs and the decreased difficulty in removing the blockages in the middle section inside the CNTs. Under the hydrated-cation–π interactions, the ultra-short CNTs with few end caps and blockages could highly efficiently enrich ions. [ABSTRACT FROM AUTHOR]

Intimate partner violence (IPV) is prevalent among young sexual and gender minorities assigned male at birth (YSGM-AMAB). However, few studies have examined the chronicity or distinguished between minor and severe forms of IPV among YSGM-AMAB. Furthermore, while past research has documented differences in IPV by race/ethnicity, sexual identity, gender identity, income, and education in other populations, few studies have examined these sociodemographic characteristics in relation to IPV in YSGM-AMAB. Thus, the present study aims to: (1) estimate past year prevalence and chronicity of minor and severe forms of IPV victimization and perpetration in a diverse sample of (N = 665) YSGM-AMAB in New York City, and (2) examine differences in IPV prevalence and chronicity by the aforementioned sociodemographic characteristics. Cross-sectional data from [BLINDED] informed these descriptive and inferential analyses. Nearly half of all participants reported past year IPV victimization and approximately 40% reported perpetration. Psychological violence was the most common form of victimization, followed by sexual, physical, and injury victimization. Psychological violence was the most common form of perpetration, followed by physical, sexual, and injury perpetration. Regarding sociodemographic differences in last year IPV prevalence, bisexual, transgender, and lower income YSGM-AMAB were more likely to report several subtypes of IPV victimization. Whereas Asian/API, bisexual, transgender, and lower income participants were more likely to report several subtypes of IPV perpetration. Regarding last year IPV chronicity, non-graduate YSGM-AMAB reported more instances of two subtypes of IPV victimization, while Black, White, cisgender, upper income, non-graduate participants reported more instances of several subtypes of IPV perpetration. These findings may be used to develop IPV prevention and intervention programs, inform future research endeavors, and develop and strengthen policies that reduce sociodemographic inequalities and promote more favorable sociopolitical conditions for YSGM-AMAB. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) indium selenide (InSe) has been widely studied for application in transistors and photodetectors, which benefit from its excellent optoelectronic properties. Among the three specific polytypes (γ -, ϵ - and β -phase) of InSe, only the crystal lattice of InSe in β -phase (β -InSe) belongs to a non-symmetry point group of |$D_{6h}^4$|⁠ , which indicates stronger anisotropic transport behavior and potential in the polarized photodetection of β -InSe-based optoelectronic devices. Therefore, we prepare the stable p-type 2D-layered β -InSe via temperature gradient method. The anisotropic Raman, transport and photoresponse properties of β -InSe have been experimentally and theoretically proven, showing that the β -InSe-based device has a ratio of 3.76 for the maximum to minimum dark current at two orthogonal orientations and a high photocurrent anisotropic ratio of 0.70 at 1 V bias voltage, respectively. The appealing anisotropic properties demonstrated in this work clearly identify β -InSe as a competitive candidate for filter-free polarization-sensitive photodetectors. [ABSTRACT FROM AUTHOR]

The in-plane anisotropy of monolayer InSe plays a critical role in the application of photodetectors. In this work, through nonequilibrium Green's function density functional theory (NEGF-DFT) and time-dependent density functional theory (TD-DFT) calculations, we investigated the anisotropic quantum transport in darkness and under linearly polarized light, and explored the role of surface-bound excitons in the anisotropic photocurrent. The anisotropic dark quantum transport is attributed to different potential barriers in the zigzag and armchair orientations (Id-zig/Id-arm = 1.2 × 102). Linearly polarized photocurrent calculations show that the extinction ratio reaches a maximum value of 105.67. Moreover, surface-bound exciton calculations via TD-DFT revealed that the strong anisotropic photocurrent derives from surface-bound excitons generated in the In 5pz, Se 4pz, and Se 4dz2 orbitals. InSe shows tremendous potential for use in field-effect transistors, flexible nano- and optoelectronics, and polarized light devices. [ABSTRACT FROM AUTHOR]

Unlike traditional two-dimensional layered materials, tellurium (Te) shows its one-dimensional van der Waals structure and triggers intensive researches. Through a density functional theory coupled with the nonequilibrium Green's function calculation, we found that bilayer tellurene has a broad photoelectric response over the range from the visible to the near-infrared region. Besides, bilayer tellurene photodetector presents an ultra-strong anisotropic photo-responsivity and an ultra-high extinction ratio (~2812 at the photon energy of 3.4 eV) because of its non-layer/chain structure, which is superior to the antimonene (~145) and phosphorene/blue phosphorene bilayers (~240). Time-domain first principle study further reveals that the ultra-strong anisotropy comes from the transition of Te 5p bonding orbitals along or perpendicular to the chain directions. With these excellent optoelectronic merits, bilayer tellurene may become a promising candidate for next-generation photoelectronic devices. [ABSTRACT FROM AUTHOR]

The identification of urban functional areas is essential for urban planning and sustainable development. Spatial grids are the basic units for the implementation of urban plans and management by cities or development zones. The emergence of internet "big data" provides new ideas for the identification of urban functional areas. Based on point of interest (POI) data from Baidu Maps, the Xicheng District of Beijing was divided into grids with side lengths of 200, 500, and 1000 m in this study. The kernel density method was used to analyze the spatial structure of POI data. Two indicators, that is, the frequency density and category ratio, were then used to identify single- and mixed-functional areas. The results show that (1) commercial and financial areas are concentrated in the city center and multiple business centers have not developed; (2) scenic areas account for the largest proportion of single-functional areas in the Xicheng District of Beijing, followed by education and training, residence, and party and government organizations areas; and (3) the 200 × 200 m and 500 × 500 m grids are the most suitable for the identification of single- and mixed-functional areas, respectively. [ABSTRACT FROM AUTHOR]

In contrast to zero‐bandgap metallic graphene, the binary semiconducting compound, InSe, possesses a tunable bandgap. Herein, a range of particle sizes of β‐InSe from bulk to few‐layer nanosheets and quantum dots are carefully prepared. The size‐dependent bandgap variation and photon‐induced carrier dynamics of InSe are systemically investigated. In contrast to the normal size‐dependent carrier lifetime trend observed at 700 nm, anomalous size‐independent carrier decay is observed at 500 nm. Through time‐dependent density functional theory calculations, the normal carrier lifetimes at lower probe photon energies are attributed to in‐plane excitons, whereas the abnormal size‐independent carrier lifetimes at higher probe photon energies are found to be stimulated by surface‐bound excitons. In view of the robust surface exciton, this suggests that InSe may possess an outstanding optoelectronic performance in the shorter wavelength range. Through photoelectrochemical detection experiments, it is confirmed that InSe features a high photocurrent density and stability and, in particular, a more distinct photoresponse at short wavelengths than at longer ones. Comprehending and quantifying the role of the surface‐bound excitons in InSe across a broad range of semiconductor nanostructures and their fundamental properties may play an important role in understanding the physical properties of 2D III–VI compound materials. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) indium selenide (InSe) has been widely studied for application in transistors and photodetectors, which benefit from its excellent optoelectronic properties. Among the three specific polytypes ( γ -, ϵ - and β -phase) of InSe, only the crystal lattice of InSe in β -phase ( β -InSe) belongs to a non-symmetry point group of [Formula: see text], which indicates stronger anisotropic transport behavior and potential in the polarized photodetection of β -InSe-based optoelectronic devices. Therefore, we prepare the stable p-type 2D-layered β -InSe via temperature gradient method. The anisotropic Raman, transport and photoresponse properties of β -InSe have been experimentally and theoretically proven, showing that the β -InSe-based device has a ratio of 3.76 for the maximum to minimum dark current at two orthogonal orientations and a high photocurrent anisotropic ratio of 0.70 at 1 V bias voltage, respectively. The appealing anisotropic properties demonstrated in this work clearly identify β -InSe as a competitive candidate for filter-free polarization-sensitive photodetectors., (© The Author(s) 2021. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)