Highly efficient conductors are strongly desired because they can lead to higher working performance and less energy consumption in their wide range applications. However, the improvements on the ...electrical conductivities of conventional conductors are limited, such as purification and growing single crystal of metals. Here, by embedding graphene in metals (Cu, Al, and Ag), the trade‐off between carrier mobility and carrier density is surmount in graphene, and realize high electron mobility and high electron density simultaneously through elaborate interface design and morphology control. As a result, a maximum electrical conductivity three orders of magnitude higher than the highest on record (more than 3,000 times higher than that of Cu) is obtained in such embedded graphene. As a result, using the graphene as reinforcement, an electrical conductivity as high as ≈117% of the International Annealed Copper Standard and significantly higher than that of Ag is achieved in bulk graphene/Cu composites with an extremely low graphene volume fraction of only 0.008%. The results are of significance when enhancing efficiency and saving energy in electrical and electronic applications of metals, and also of interest for fundamental researches on electron behaviors in graphene.
Ultrahigh electrical conductivity ≈3000 times higher than that of Cu is realized in graphene embedded in metals. As a result, the corresponding graphene/Cu composites show an electrical conductivity significantly higher than that of Ag. Such graphene/metal interactions provide a unique platform to explore electron behaviors in graphene, and the results open up new opportunities for graphene's applications.
Against the background of China’s strengthening of finance and accounting supervision, this study examines the practice among listed companies of changing signing auditors at the last minute and ...explores whether Chinese investors can capture this information in a timely manner. We find that China’s capital market responds significantly negatively to these last-minute changes, implying that investors perceive a potential negative impact of this behavior. Cross-sectional analyses suggest that the characteristics of the change event, recent corporate events, and accounting firm capability significantly affect the stock price response. Furthermore, in terms of the individual characteristics of signing auditors, external investors appear to comprehensively consider busyness level, industry experience, and the timing of the change to determine the causes and effects of the auditor change and make different market reactions accordingly. In addition, consistent with investor perceptions, we find that last-minute changes significantly impair the quality of financial statements, indicating that external investors’ judgments based on information about changes in signing auditors are rational and effective.
Background The purpose of this study was to explore a new estrogen receptor (ER) and/or progesterone receptor (PR)+ and human epidermal growth factor receptor 2 (HER2)- breast cancer prognostic ...model, called the extended Cox prognostic model, for determining the cutoff values for multiple continuous prognostic factors and their interaction via the new model concept and variable selection method. Methods A total of 335 patients with ER/PR+ and HER2- breast cancer were enrolled for the final analysis. The primary endpoint was breast cancer-specific mortality (BCSM). Prognostic factors (histological grade, histological type, stage, T, N, lymphovascular invasion (LVI), P53, Ki67, ER, PR, and age) were included in this study. The four continuous variables (Ki67, ER, PR, and age) were partitioned into a series of binary variables that were fitted in the multivariate Cox analysis. A smoothly clipped absolute deviation (SCAD) variable selection method was used. Model performance was expressed in discrimination and calibration. Results We developed an extended Cox model with a time threshold of 164-week (more than 3 years) postoperation and developed a user-friendly nomogram based on our extended Cox model to facilitate clinical application. We found that the cutoff values for PR, Ki67, and age were 20%, 60%, and 41-55 years, respectively. There was an interaction between age and PR for patients aged greater than or equal to 41 years and PR greater than or equal to 20% at 164-week postoperation: the older the patients with ER/PR+, HER2-, and PR greater than or equal to 20% were, the lower the survival and more likely to recur and metastasize exceeding 164 weeks (more than 3 years) after surgery. Conclusions Our study offers guidance on the prognosis of patients with ER/PR+ and HER2- breast cancer in China. The new concept can inform modeling and the determination of cutoff values of prognostic factors in the future. Keywords: Breast cancer, Estrogen receptor, Progesterone receptor, Human epidermal growth factor receptor 2, Clinicopathological prognostic factor, Prognostic model
River system is critical for the future sustainability of our planet but is always under the pressure of food, water and energy demands. Recent advances in machine learning bring a great potential ...for automatic river mapping using satellite imagery. Surface river mapping can provide accurate and timely water extent information that is highly valuable for solid policy and management decisions. However, accurate large-scale river mapping remains challenging given limited labels, spatial heterogeneity and noise in satellite imagery (e.g., clouds and aerosols). In this paper, we propose a new multi-source data-driven method for large-scale river mapping by combining multi-spectral imagery and synthetic aperture radar data. In particular, we build a multi-source data segmentation model, which uses contrastive learning to extract the common information between multiple data sources while also preserving distinct knowledge from each data source. Moreover, we create the first large-scale multi-source river imagery dataset based on Sentinel-1 and Sentinel-2 satellite data, along with 1013 handmade accurate river segmentation mask (which will be released to the public). In this dataset, our method has been shown to produce superior performance (F1-score is 91.53%) over multiple state-of-the-art segmentation algorithms. We also demonstrate the effectiveness of the proposed contrastive learning model in mapping river extent when we have limited and noisy data.
A ternary solid solution (0.935–x)Bi0.5Na0.5TiO3–0.065BaTiO3–xSrTiO3 (BNBST, BNBSTx), reported in our previous work, that exhibits a large strain response at a critical composition, was investigated ...with the emphasis on its bipolar fatigue behavior. The results indicated that BNBST with a high SrTiO3 content owning an ergodic relaxor state exhibited fatigue-free behavior after 106 cycles. Furthermore, unexpected almost fatigue-free behavior was also observed in BNBST with a low SrTiO3 concentration which has a typical ferroelectric long-range order. The excellent fatigue properties are quite favorable for practical applications.
As state-of-the-art fabrication techniques are approaching the 3 nm size, the traditional silicon-based circuit faces huge challenges. Transistors based on two-dimensional (2D) materials have ...attracted much attention as potential alternative candidates. However, critical performances including the subthreshold swing (SS), on/off ratio, and magnitude of the on-state current for 2D transistors around 3 nm size are far less to be studied well. In this work, we propose in-plane Schottky-barrier field-effect transistors (SBFETs) with a 4-nm channel based on the lateral heterostructure of monolayer 1T/2H MoTe2 and WTe2. The electric transport properties are investigated by first-principles quantum transport simulations. At a 0.64 V bias, the WTe2 SBFET has an on-state current of 3861 μA/μm, with a 4.5 × 104 on/off ratio and an SS of 87 mV/dec, while the MoTe2 SBFET has an on-state current of 1480 μA/μm, with a large on/off rate of 3.6 × 105 and an SS of 78 mV/dec. Our results suggest that FETs based on the lateral heterostructure of 1T/2H MoTe2 (WTe2) are promising candidates for high-performance 2D transistors.
This letter presents a new method for crater detection based on infrequently used morphological characteristics. Pixels representing the center and rim of each crater are connected and used to deduce ...its location and size. Based on the different characteristics shown by simple bowl-shaped and complex craters, two strategies are developed. The centers and rims of simple craters are detected directly using the original digital elevation models (DEMs). When it comes to complex ones, the slopes of DEMs and their derivatives are extracted to replace the original models. Methods for removing false craters are also developed. The characteristics of the new crater detection algorithm are as follows: 1) It avoids some deficiencies of previous methods and thus can detect new craters to complete current crater catalogs; and 2) the efficiency of the method is guaranteed due to its low time complexity. The new algorithm performs better when compared with the flooded object-oriented approach using Chang'E-1 DEMs in the same sample region, and it extends the LU60645GT catalog by 26.8% and 37.5% in two distinct areas when the crater diameters are larger than 6 km.
Recent developments in data mining and machine learning approaches have brought lots of excitement in providing solutions for challenging tasks (e.g., computer vision). However, many approaches have ...limited interpretability, so their success and failure modes are difficult to understand and their scientific robustness is difficult to evaluate. Thus, there is an urgent need for better understanding of the scientific reasoning behind data mining and machine learning approaches. This requires taking a transdisciplinary view of data science and recognizing its foundations in mathematics, statistics, and computer science. Focusing on the geospatial domain, we apply this crucial transdisciplinary perspective to five common geospatial techniques (hotspot detection, colocation detection, prediction, outlier detection and teleconnection detection). We also describe challenges and opportunities for future advancement.
The revealed “Christmas-tree” nanostructures in the cover and ground scales of the butterfly
Morpho menelaus are responsible for the observed iridescent blue color and the diffraction pattern of the ...wings. The aspect ratio of nanostructures in ground scales is more than 5 times higher than that of
Morpho peleides cover scales. Inspired by the butterfly, artificial nanostructures are fabricated successfully by templating the scales imbricating in the wings with low-temperature atomic layer deposition (ALD) methods. Through structural characterizations and optical measurements, we reveal that the hybrid structures inherit not only the morphology of the scales with high fidelity but also the homologous optical features including iridescence and diffraction. Besides, water contact angle measurements on both uncoated and coated wings show hydrophobic results. The integration of bio-templates and ALD methods provide a potential route to fabricate the nanostructures with multi-functional features, which may be especially crucial in the applications of innovative functional optical devices.
► “Christmas-tree” nanostructures contribute to the visual effects of
Morpho menelaus. ► ALD achieves comformal replication even with high aspect ratio bio-templates. ► Comprehensive optical features of
Morpho butterflies are inherited in coated wings. ► Hydrophobic feature of
Morpho butterflies is inherited in coated wings.
We performed a meta‐analysis to evaluate the oncological results in women with wound complications following mastectomy and immediate breast reconstruction. A systematic literature search up to ...August 2022 was performed and 1618 subjects with mastectomy and immediate breast reconstruction at the baseline of the studies; 443 of them were with wound complications, and 1175 were with no wound complications as a control. Odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) were calculated to assess the oncological results in women with wound complications following mastectomy and immediate breast reconstruction using dichotomous or contentious methods with a random or fixed‐effect model. The wound complications had a significantly longer length of time to adjuvant therapy (MD, 9.44; 95% CI, 4.07–14.82, P < .001) compared with no wound complications in subjects with mastectomy and immediate breast reconstruction. However, no significant difference was found between wound complications and no wound complications in subjects with mastectomy and immediate breast reconstruction in breast cancer recurrence (OR, 1.96; 95% CI, 0.95–4.06, P = .07), death rates (OR, 1.95; 95% CI, 0.89–4.27, P = .09), and kind of immediate breast reconstruction (OR, 1.01; 95% CI, 0.53–1.92, P = .98). The wound complications had a significantly longer length of time to adjuvant, however, no significant difference was found in breast cancer recurrence, death rates, and kind of immediate breast reconstruction. The analysis of outcomes should be done with caution even though no low sample size was found in the meta‐analysis but a low number of studies was found in certain comparisons.
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