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Optical functions and transitions are essential for a material to reveal the light–matter interactions and promote its applications. Here, we propose a quantitative strategy to systematically identify the critical point (CP) optical transitions of 2D semiconductors by combining the spectroscopic ellipsometry (SE) and DFT calculations. Optical functions and CPs are determined by SE, and connected to DFT band structure and projected density of states via equal-energy and equal-momentum lines. The combination of SE and DFT provides a powerful tool to investigate the CP optical transitions, including the transition energies and positions in Brillouin zone (BZ), and the involved energy bands and carries. As an example, the single-crystal monolayer WS2 is investigated by the proposed method. Results indicate that six excitonic-type CPs can be quantitatively distinguished in optical function of the monolayer WS2 over the spectral range of 245–1000 nm. These CPs are identified as direct optical transitions from three highest valence bands to three lowest conduction bands at high symmetry points in BZ contributed by electrons in S-3p and W-5d orbitals. Results and discussion on the monolayer WS2 demonstrate the effectiveness and advantages of the proposed method, which is general and can be easily extended to other materials.

Invasive fractional flow reserve (FFR) measured by a pressure wire is a reference standard for evaluating functional stenosis in coronary artery disease. Coronary computed tomography angiography-derived fractional flow reserve (CT-FFR) uses advanced computational analysis methods to noninvasively obtain FFR results from a single conventional coronary computed tomography angiography data to evaluate the hemodynamic significance of coronary artery disease. More and more evidence has found good correlation between the results of noninvasive CT-FFR and invasive FFR. CT-FFR has proven its potential in optimizing patient management, improving risk stratification and prognosis, and reducing total health care costs. However, there is still a lack of standardized interpretation of CT-FFR technology in real-world clinical settings. This expert consensus introduces the principle, workflow, and interpretation of CT-FFR; summarizes the state-of-the-art application of CT-FFR; and provides suggestions and recommendations for the application of CT-FFR with the aim of promoting the standardized application of CT-FFR in clinical practice.

A series of transparent ceramics with the composition of Al(8+x)/3O4−xNx (x = 0.299–0.575) were prepared without any sintering additives by presintering combined with hot isostatic pressing (HIP). The composition of the samples was accurately determined to investigate the effect of nitrogen content on optical properties in γ-AlON. The samples with x = 0.299–0.510 possessed excellent in-line transmittance (>80 %) from the visible light to middle-infrared wavelengths, which was attributed to rare pores and high density in these ceramics. As the increasing nitrogen content, the refractive index increased, the UV absorption edge presented a red-shift, and the transmittance at about 5.5 μm decreased. The Sellmeier optical coefficients Eo, λo, So, and Ed were obtained on the basis of the single-term oscillator equation, which associates directly with the electronic energy band structure. The origin of the high refractive index is ascribed to the large electronic polarizability of nitrogen ions.

A green, efficient, and high active catalytic system for the hydrogenation of ketones and aldehydes to produce corresponding alcohols under atmospheric-pressure H2 gas and ambient temperature conditions was developed by a water-soluble metal–ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(OH)][Na] in water without addition of a base. The catalyst exhibited high activity for the hydrogenation of ketones and aldehydes. Furthermore, it was worth noting that many readily reducible or labile functional groups in the same molecule, such as cyan, nitro, and ester groups, remained unchanged. Interestingly, the unsaturated aldehydes can be also selectively hydrogenated to give corresponding unsaturated alcohols with remaining C=C bond in good yields. In addition, this reaction could be extended to gram levels and has a large potential of wide application in future industrial.

Background Differentiating diagnosis between the benign schwannoma and the malignant counterparts merely by neuroimaging is not always clear and remains still confounding in many cases because of atypical imaging presentation encountered in clinic and the lack of specific diagnostic markers. Purpose To construct and validate a novel deep learning model based on multi-source magnetic resonance imaging (MRI) in automatically differentiating malignant spinal schwannoma from benign. Material and Methods We retrospectively reviewed MRI imaging data from 119 patients with the initial diagnosis of benign or malignant spinal schwannoma confirmed by postoperative pathology. A novel convolutional neural network (CNN)-based deep learning model named GAIN-CP (Guided Attention Inference Network with Clinical Priors) was constructed. An ablation study for the fivefold cross-validation and cross-source experiments were conducted to validate the novel model. The diagnosis performance among our GAIN-CP model, the conventional radiomics model, and the radiologist-based clinical assessment were compared using the area under the receiver operating characteristic curve (AUC) and balanced accuracy (BAC). Results The AUC score of the proposed GAIN method is 0.83, which outperforms the radiomics method (0.65) and the evaluations from the radiologists (0.67). By incorporating both the image data and the clinical prior features, our GAIN-CP achieves an AUC score of 0.95. The GAIN-CP also achieves the best performance on fivefold cross-validation and cross-source experiments. Conclusion The novel GAIN-CP method can successfully classify malignant spinal schwannoma from benign cases using the provided multi-source MR images exhibiting good prospect in clinical diagnosis.

Tellurene's giant in-plane optical anisotropy brings richer physics and an extra degree of freedom to regulate its optical properties for designing novel and unique polarization-sensitive devices. Here, we quantitatively evaluate the in-plane optical anisotropy of tellurene and further reveal its physical origins by combining imaging Mueller matrix spectroscopic ellipsometry (MMSE) and first-principles calculations. The anisotropic complex refractive indices and dielectric functions, as well as the derived giant birefringence (|Δ

Anisotropy in low-dimensional materials offers an extra degree of freedom to understand and tune the peculiar or potential properties to design novel electronic, optical, thermal, and optoelectroni...

Image well logging is an intuitive approach to identify fractures of reservoir for oil and gas exploration. However, these logging images are rare and nonannotated. A method of unsupervised segmentation network based on convolutional neural network is adopted to automatically extract pixels pertaining to fracture information in this paper. We propose a modified model to accomplish domain adaptation from the source domain with similar fractures information to the target domain, which can improve the accuracy of fracture recognition. The network is trained in the source domain with ground truth and tested in the target domain without any labels. Compared with the experimental results of other classical methods, this method has demonstrated satisfactory performances in terms of accuracy and visual quality even if the logging image dataset is insufficient.

Due to the advantages of being non-contact, non-destructive, highly efficient, and low in cost, scatterometry has emerged as a powerful technique for nanostructure metrology. In this paper, we propose an angle-resolved scatterometer composed of a scattered light acquisition channel and a spatial imaging channel, which is capable of detecting multi-order diffracted light in a single measurement. Since the high numerical aperture objective lens is usually employed in an angle-resolved scatterometer, the polarization effect of the objective lens introduced by the non-normal incidence and installation stress should be considered. An in-situ calibration method for the objective lens’s polarization effects is proposed, in which a known analyzer is appended to the output light path to enable the extraction of the ellipsometric parameters of isotropic samples. Then the polarization effect of the objective lens can be determined in-situ by fitting the measured ellipsometric parameters to the calculated ones. With the objective lens polarization effect being considered, significant improvements in the accuracy and repeatability precision can be achieved in the metrology of the film thickness and grating topography parameters.

With China’s ambitious goals of carbon capping by 2030 and carbon neutrality by 2060, the multi-energy coupled clean heating technology represented by solar-air source heat pumps is developing rapidly. In order to solve the above problems, this paper analyzes the characteristics of the multi-energy coupled heating system by establishing a virtual simulation model and optimizing the system operation and control modes. Technical support is provided for efficiently utilizing multi-energy coupled heating technology in rural buildings. In this paper, the mathematical model of the system is established by analyzing the form and working principle of the solar-air source heat pump coupled heating system. Initially, three operation strategies are constructed: priority utilization of solar energy strategy (Strategy I), air source heat pump fixed temperature switching strategy (Strategy II), and air source heat pump timed switching strategy (Strategy III), laying the foundation for operation strategy optimization. The dynamic load change pattern of the building in winter was calculated using TRNSYS software, based on which equipment selection was carried out, and a simulation model of the solar-air source heat pump coupled heating system was established. The system operation strategy was optimized. A temperature difference control strategy was used for the solar collector cycle control optimization, which increased the solar collector efficiency by 12% compared to the fixed temperature control strategy. Based on typical climate data, the heating season was divided into 10 phases according to a 15-day cycle, and three operation strategies were optimized and compared for each phase with the goal of comprehensive system energy efficiency. After comparison and analysis, strategy 1 and 3 have their advantages in different stages of the heating season. The operation strategies with higher system energy efficiency in each stage were combined in the heating season, called combined operation strategy (strategy 4), and compared with other strategies in the heating season. Compared with strategy 1 and strategy 3 in the whole heating season, the system energy efficiency of strategy 4 was improved by 3%-6%. This indicates that strategy 4 has better operation effect.

Purpose To analyze the initial CT features of different clinical categories of COVID-19. Material and methods A total of 86 patients with COVID-19 were analyzed, including the clinical, laboratory and imaging features. The following imaging features were analyzed, the lesion amount, location, density, lung nodule, halo sign, reversed-halo sign, distribution pattern, inner structures and changes of adjacent structures. Chi-square test, Fisher’s exact test, or Mann–Whitney U test was used for the enumeration data. Binary logistic regression analysis was performed to draw a regression equation to estimate the likelihood of severe and critical category. The forward conditional method was employed for variable selection. Results Significant statistical differences were found in age (p = 0.001) and sex (p = 0.028) between mild and moderate and severe and critical category. No significant difference was found in clinical symptoms and WBC count between the two groups. The majority of cases (91.8%) showed multifocal lesions. The presence of GGO was higher in severe and critical category than in the mild and moderate category. (57.8% vs.31.7%, p = 0.015). Lymphocyte count was important indicator for the severe and critical category. Conclusion The initial CT features of the different clinical category overlapped. Combining with laboratory test, especially the lymphocyte count, could help to predict the severity of COVID-19. Supplementary Information The online version contains supplementary material available at 10.1007/s42058-021-00056-4.

Government research and development (R&D) subsidy is one of the main policy instruments to deal with market failure, and its effectiveness has attracted attention increasingly. This study investigates the impact of two types of government R&D subsidies on innovation using the data of Chinese listed enterprises from 2010 to 2016. We find that compared with ex-post rewards, ex-ante grants have a better effect on innovation performance by stimulating private R&D investment. Additionally, the effectiveness of government R&D subsidies is weakened in enterprises engaging in rent-seeking and political connections. This study provides a new perspective for understanding the effect of government R&D subsidies, and the research conclusions are the relevant reference for the government to improve the efficiency of allocating public funds.

Lutein belongs to the carotenoid compound family, which is a special group of hydrocarbon pigments characterized by π-conjugated double bonds in the molecular backbone. Four lutein crystal forms wi...

Hydrogen storage materials are the key to hydrogen energy utilization. However, current materials can hardly meet the storage capacity and/or operability requirements of practical applications. Here we report an advancement in hydrogen storage performance and related mechanism based on a hydrofluoric acid incompletely etched MXene, namely, a multilayered Ti2CTx (T is a functional group) stack that shows an unprecedented hydrogen uptake of 8.8 wt% at room temperature and 60 bar H2. Even under completely ambient conditions (25 °C, 1 bar air), Ti2CTx is still able to retain ~4 wt% hydrogen. The hydrogen storage is stable and reversible in the material, and the hydrogen release is controllable by pressure and temperature below 95 °C. The storage mechanism is deduced to be a nanopump-effect-assisted weak chemisorption in the sub-nanoscale interlayer space of the material. Such a storage approach provides a promising strategy for designing practical hydrogen storage materials. An incompletely etched Ti2CTx stack exhibits highly reversible hydrogen storage under near-ambient conditions by nanopump-effect-assisted weak chemisorption.

High-performance piezoelectric thin films generally contain toxic lead that limits the application scenarios especially in wearable and medical devices. Alternative lead-free piezoelectric materials such as Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) have been proved to have high biocompatibility and competitive piezoelectric performances. However, few have reported BCZT thin films integrated within flexible electronics. To fill this gap, we prepare BCZT thin films on flexible mica substrates and based on that fabricate piezoelectric nanogenerators (PENGs). The piezoelectric modulus d33 of the BCZT thin films evaluated from the established system reaches 150 pC N−1, which is comparable to those of films grown on single crystal substrates. The BCZT-based PENG can charge capacitors under mechanical excitation, indicating that it has broad application prospects in the field of flexible self-powered electronics.

Rationale and Objectives To describe the rational and design of a population-based comparative study. The objective of the study is to assess the screening performance of volume-based management of CT-detected lung nodule in comparison to diameter-based management, and to improve the effectiveness of CT screening for chronic obstructive pulmonary disease (COPD) and cardiovascular disease (CVD), in addition to lung cancer, based on quantitative measurement of CT imaging biomarkers in a Chinese screening setting. Materials and Methods A population-based comparative study is being performed, including 10,000 asymptomatic participants between 40 and 74 years old from Shanghai urban population. Participants in the intervention group undergo a low-dose chest and cardiac CT scan at baseline and 1 year later, and are managed according to NELCIN-B3 protocol. Participants in the control group undergo a low-dose chest CT scan according to the routine CT protocol and are managed according to the clinical practice. Epidemiological data are collected through questionnaires. In the fourth year from baseline, the diagnosis of the three diseases will be collected. Results The unnecessary referral rate will be compared between NELCIN-B3 and standard protocol for managing early-detected lung nodules. The effectiveness of quantitative measurement of CT imaging biomarkers for early detection of lung cancer, COPD and CVD will be evaluated. Conclusion We expect that the quantitative assessment of the CT imaging biomarkers will reduce the number of unnecessary referrals for early detected lung nodules, and will improve the early detection of COPD and CVD in a Chinese urban population. Trial Registration ClinicalTrials.gov, NCT03988322. Registered on 14 June 2019.