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A novel theory and design methodology for continuous-mode dual-input outphasing amplifiers (CM-OPA) is proposed to enhance the bandwidth of mixed-mode Chirex PAs. The design procedure relies on a modified analytical role-exchange Doherty-Chireix continuum theory which doubles the design space for the realization of high-efficiency PAs with a mode of operation continuously changing between the Chireix mode and two role-exchange hybrid Doherty-Chireix outphasing modes as the frequency varies up and down, respectively. Using this theory, a mixed-mode CM-OPA with constant output power back-off level and constant saturated power is developed. The CM-OPA theory is first verified at the current-source reference planes for a frequency range from 1.3 GHz to 2.0 GHz for a GaN HEMT. The proposed CM-OPA is then implemented at the package reference planes using the embedding model to synthesize the combiner circuit across the entire frequency bandwidth. The 1.3 to 2.0 GHz bandwidth-enhanced CM-OPA was fabricated and characterized using both continuous-wave and modulated signals. When driven by a 20-MHz LTE signal with 7.1 dB peak-to-average-power ratio (PAPR), the proposed CM-OPA achieves better than -45 dBc adjacent channel leakage ratio (ACLR) and higher than 44% power-added efficiency (PAE) after digital predistortion linearization at 1.3/1.6/1.8 GHz.

The movement mode of snakes is crawling, and the living environment of snakes with numerous branches and stones will cause plenty of wear for the snake scales. There are plenty of surface structures and morphology on snake scales to avoid severe wear. Among them, the research towards the keeled structure on snake scales is missing. Therefore, in this research, the wear resistance improvement of the keeled structure on the snake scales and the overlapped distribution of snake scales are investigated. The keeled and smooth snake scales were 3D printed and they were distributed on the substrate in the overlapped or paralleled ways. Besides these four samples with keeled/smooth scales and overlapped/paralleled distributed, there is also a reference sample with the same thickness. Based on the tribology test, the number of grooves of samples with the keeled structures is higher than that of samples with smooth surfaces, which indicates that the keeled structure dramatically enhances the wear resistance of snake scales, especially during the wear in the vertical direction. The experiment on surface morphology greatly compromised the result of the tribology test. In addition, the bottom portion of the keeled snake scales can be protected by the keeled structure. Besides, the overlapped distribution can protect the central region of snake scales and provide double-layer protection of the snake body. Overall, the keeled structure and the overlapped distribution play a significant part in the improvement of wear resistance of the snake skin. These findings can enhance the knowledge of the reptiles-mimic surface structure and facilitate the application of military uniforms under high-wear conditions.

A 95% efficiency reusable adaptive time control bidirectional buck charge converter for wide input range operation is presented in this brief. For keeping the switching frequency stable, a reusable adaptive time generator is proposed to improve the transient response and stability of the system. In the buck charging and reverse boost discharging mode, the circuit adopts adaptive off-time control and on-time control, respectively. In order to ensure that the converter can work over a wide input range in the above two working modes, a maximum voltage selection circuit is used to generate a stable high-voltage output signal as the power supply voltage of the system. The proposed bidirectional converter has been fabricated using 0.18- $\mathbf {\mathrm {\mu }}\text{m}$ BCD process. Measurement results show that the converter has good output accuracy. The switching frequency is centered at 750kHz with less than 1.5% variation when the input voltage is 4.5-14V in the buck mode and 2.6-4.5V in the boost mode. The maximum conversion efficiency is up to 95%. Its minimum input starting voltage can be as low as 2.6V.

Hyperspectral unmixing (HSU), which aims to identify constituent materials and estimate the corresponding proportions in a scene, is an essential research topic in remote sensing. Most deep learning-based methods are data-inspired, relying on massive amounts of data to train black-box-like networks, while a few model-inspired unmixing networks only consider the spectral features of the pixel, ignoring the exploration of spatial information between pixels. In this article, we design a network topology according to the classical iterative algorithm, and the large number of learnable parameters contained in the network is continuously updated through data fitting. In other words, we integrate the concepts of both model- and data-driven and propose a deep interpretable fully convolutional neural network (DIFCNN). The iteration of the classic sparse unmixing algorithm is unfolded to provide guidance for the network structure and incorporate prior knowledge into the network. Meanwhile, 2-D convolutional layers are employed to automatically learn the spatial information at different scales. A known spectral library is used as a prior to initialize network parameters and reconstruct the image. The DIFCNN adopts an end-to-end training strategy; in addition, we establish a new loss function that adds a joint sparse constraint on the abundance result to the cross-entropy loss. Experiments on both synthetic and real datasets show that the performance of the DIFCNN not only outperforms the sparse unmixing by variable splitting and augmented Lagrangian (SUnSAL) and its improved algorithms but also is highly competitive in the state-of-the-art methods of deep learning.

Exploring the spatio-temporal variations of farmland landscape patterns in a traditional agricultural region can provide scientific support for decision-making on sustainable rural land use and rural vitalization development. This study established a comprehensive evaluation index for farmland fragmentation with multiple aspects (dominance, integrity, aggregation, regularity, and connectivity) at the county scale. The goal was to identify the evolution of farmland fragmentation in the traditional agricultural region of the Huang-Huai-Hai Plain during 2000–2015 and investigate underlying drivers using panel data of 359 counties. Results showed an accelerating but fluctuating fragmentation pattern of the farmland landscape. The indexes of dominance, integrity, and aggregation of farmland decreased most sharply, while the index of connectivity increased. Furthermore, the evolution of the farmland fragmentation pattern showed significant spatio-temporal heterogeneity, which is similar to the trajectory of urbanization and land use transition. Farmland fragmentation in municipal districts also emerged earlier and was more severe than in county-level cities and counties. Factors influenced by advancing urbanization include the proportion of artificial land, population density, and proportion of primary industry; these factors drove the evolution of farmland fragmentation. In contrast, the increase in income of rural residents and production efficiency of farmland were the key factors contributing to the improvement in farmland connectivity.

Longitudinal optical field modulation is of critical importance in a wide range of applications, including optical imaging, spectroscopy, and optical manipulation. However, it remains a considerable challenge to realize a uniformly distributed light field with extended depth-of-focus. Here, a high-efficiency extended depth-of-focus metalens is proposed by adjoint-based topology-shape optimization approach, wherein the theoretical electric field intensity corresponding to a variable focal-length phase is utilized as the figure of merit. Using a dozen of metalens with random structure parameters as initial structures, the average focal depth of topology-shape optimized metalens is greatly improved up to 18.80 μm (about 29.7λ), which is 1.54 times higher than the diffraction-limited focal depth. Moreover, all the topology-shape optimized metalens exhibit high diffraction efficiency exceeding 0.7 over the whole focal depth range, which is approximately three times greater than that of the forward design. Our results offer a new insight into the design of extended depth-of-focus metalens and may find potential applications in imaging, holography, and optical fabrication.

Metabolic programs are crucial for regulatory T (T reg) cell stability and function, but the underlying mechanisms that regulate T reg cell metabolism are elusive. Here, we report that lysosomal TRAF3IP3 acts as a pivotal regulator in the maintenance of T reg cell metabolic fitness. T reg–specific deletion of Traf3ip3 impairs T reg cell function, causing the development of inflammatory disorders and stronger antitumor T cell responses in mice. Excessive mechanistic target of rapamycin complex 1 (mTORC1)–mediated hyper-glycolytic metabolism is responsible for the instability of TRAF3IP3-deficient T reg cells. Mechanistically, TRAF3IP3 restricts mTORC1 signaling by recruiting the serine-threonine phosphatase catalytic subunit (PP2Ac) to the lysosome, thereby facilitating the interaction of PP2Ac with the mTORC1 component Raptor. Our results define TRAF3IP3 as a metabolic regulator in T reg cell stability and function and suggest a lysosome-specific mTORC1 signaling mechanism that regulates T reg cell metabolism.

China’s investments, financial incentives and deductions in terms of ecological conservation are based at the county level. Therefore, the monitoring and assessment of the effects of ecological conservation at the county level is important to provide a scientific basis for the assessment of the ecological and environmental quality at the county scale. This paper quantitatively estimated the dynamics of high-quality ecosystems and vegetation coverage over the past 15 years, and their relationships with the number of ecological conservation programs at the county level were analyzed. Then, the effects of ecological conservation measures on ecological changes at the county level and their regional suitability were assessed and discussed. The results showed that counties with a percentage of high-quality ecosystems greater than 50% were primarily distributed in northeastern China, southern subtropical China and the southeastern Qinghai-Tibet Plateau, and those with a percentage lower than 20% were mostly distributed in northwestern China, the southwestern karst region and the North China Plain. In recent decades, ecological conservation has focused on ecologically fragile regions; more than five ecological conservation programs have been implemented in most counties of the Three River Source Region in Qinghai Province, southeastern Tibet, western Sichuan, the Qilian Mountains, southern Xinjiang and other western regions, while only one or zero have been implemented in the eastern coastal area of China. Over the past 15 years, the proportional area of high-quality ecosystems has increased in approximately 53% of counties. The vegetation coverage of counties in the Loess Plateau, Huang-Huai-Hai Plain, Beijing-Tianjin-Hebei (Jing-Jin-Ji), Sichuan-Guizhou-Chongqing, and Guangdong-Guangxi provincial-level areas has increased significantly. However, it decreased in northern Xinjiang, central Tibet, central and eastern Inner Mongolia, the Yangtze River Delta and other regions. The relationships between the numbers of ecological conservation programs and the indicators of ecosystem restoration response, such as high-quality ecosystem and vegetation coverage, do not show positive correlations. These results suggest that ecological conservation programs should be planned and implemented according to the distribution patterns of high-quality ecosystems and that restoration measures such as afforestation should follow natural principles and regional differentiation under the background of climate change.

Microbial community structure is affected by both natural processes and human activities. In coastal area, anthropegenetic activity can usually lead to the discharge of the effluent from wastewater treatment plant (WWTP) to sea, and thus the water quality chronically turns worse and marine ecosystem becomes unhealthy. Microorganisms play key roles in pollutants degradation and ecological restoration; however, there are few studies about how the WWTP effluent disposal influences coastal microbial communities. In this study, sediment samples were collected from two WWTP effluent-receiving areas (abbreviated as JX and SY) in Hangzhou Bay. First, based on the high-throughput sequencing of 16S rRNA gene, microbial community structure was analyzed. Secondly, several statistical analyses were conducted to reveal the microbial community characteristics in response to the effluent disposal. Using PCoA, the significant difference of in microbial community structure was determined between JX and SY; using RDA, water COD and temperature, and sediment available phosphate and ammonia nitrogen were identified as the key environmental factors for the community difference; using LDA effect size analysis, the most distinctive microbes were found and their correlations with environmental factors were investigated; and according to detrended beta-nearest-taxon-index, the sediment microbial communities were found to follow “niche theory”. An interesting and important finding was that in SY that received more and toxic COD, many distinctive microbes were related to the groups that were capable of degrading toxic organic pollutants. This study provides a clear illustration of eco-environmental deterioration under the long-term human pressure from the view of microbial ecology.