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Chaff jamming is a widely used passive interference method. A chaff cloud diffusion model for the widespread chaff cloud was presented. The high-density chaff cloud aerodynamic model can rapidly predict the chaff elements’ time-varying spatial orientation, location, and overall spatial distribution. Basing on these pieces of information, the radar cross section (RCS) for the single chaff fibre can be obtained based on the method of moments (MoM). For high-density chaff clouds, the attenuation and shielding effects on the signal must be considered. This paper proposed a voxel splitting method in rotated coordinates, dividing the chaff cloud into rectangular cells with one side perpendicular to the direction of radar entry. The varied polarized RCS features of the chaff cloud were simulated and analysed on this foundation. By dividing the chaff cloud into dynamic voxels and considering the uneven density distribution of the chaff cloud and the signal attenuation in each segment caused by the continuous fluctuating shape, fine-grained simulations of the chaff cloud radar echoes can be performed.

Small slope approximation (SSA) is a widely accepted approach in sea surface electromagnetic (EM) scattering studies. Nevertheless, the spatial sample interval used for sea surface should be around or even smaller than one-eighth of the incident wavelength to ensure EM scattering calculation accuracy, which requires a huge amount of computation, creating an obstacle to scattering numerical simulation, especially for high microwave band incident waves and large sea surface scenes. In this paper, a novel realization approach for SSA is proposed to significantly decrease the computation demands and computer memory requirements in sea surface scattering simulation. First, the sea surface is decomposed into two scales, and each scale has its own spatial sample interval. Then, the inclination state of the large-scale sea surface is determined under a specific wind speed. After that, scattering calculations of a typical surface cell with a finely sampled structure are completed and saved in all possible situations. Finally, scattering results for all the cells of a concrete sea surface are extracted from the saved cell scattering data base. From the different kinds of scattering result comparisons, it is demonstrated that this novel SSA realization approach can attain almost similar scattering results to exact SSA. This approach can be broadly applied in composite scattering studies, and remote sense imaging simulation of large sea surfaces with multiple targets.

為了避免積體電路遭受靜電放電的破壞，靜電放電防護元件通常被設計在電路的輸入/輸出端。操作在順偏條件的二極體適合被作為靜電放電防護元件，因此靜電放電防護二極體被廣泛應用在高頻以及高壓電路，然而靜電放電防護二極體的寄生電容卻嚴重地影響電路的高頻特性，導致信號不斷流失，為了解決信號損失的問題，靜電放電防護二極體的寄生電容必須被最小化。然而，防護元件的寄生電容能夠縮小的範圍仍然有限，一個元件同時擁有足夠的靜電放電防護能力以及小的寄生電容是相當困難的。因此，本論文提出一種低損耗焊墊的結構，能夠有效降低防護元件對高頻的影響，透過LC共振原理使K/Ka-bands中的信號損失降至最低。低損耗焊墊搭配靜電放電防護雙二極體已被實現在0.18μm互補式金氧半製程中，從高頻量測中證實，所提出之結構的信號損失較傳統結構低了六至十倍。最後，藉由各項靜電放電耐受度測試驗證，所提出之結構能夠擁有足夠高的靜電放電防護能力。 由於二極體為單向導通元件，僅適合提供一個靜電放電的路徑，需額外加入靜電放電箝制電路才能提供電路完整的防護，然而靜電放電電流透過靜電放電箝制電路排放，通常需要較遠的距離。因此，本論文提出一種雙向導通的P型二極體結構，藉由PN接面的空乏區控制其通道，當靜電放電事件發生時，通道的空乏區將消失並排放靜電電流，而在正常工作中，空乏區應切斷其通道並有足夠低的漏電流，在高壓的應用中，橫向雙擴散電晶體經常被作為靜電放電防護元件，然而橫向雙擴散電晶體的結構複雜且不易設計，使得高壓操作中的靜電放電防護設計受到挑戰。二極體不但結構簡單且有足夠的靜電放電耐受度，因此本論文針對二極體的結構去進行改良，所提出的P型空乏二極體已被實現在0.50μm互補式金氧半製程中。從直流量測結果證實，在正常工作下P型空乏二極體有足夠低的漏電流，靜電放電耐受度測試中，透過通道排放靜電電流的想法是可行的但仍有需改進的地方。最後一章節的未來工作中將會提及一些改良的結構與想法。

● Insect damaging and penetrating plastic materials has been observed since 1950s. ● Biodegradation of plastics by insects has become hot research frontiers. ● All major plastics can be biodegraded with half-live on hourly basis. ● The biodegradation is performed by the insect hosts together with gut microbiota. ● Future perspectives focus on biodegradation mechanisms and potential applications. Insects damaging and penetrating plastic packaged materials has been reported since the 1950s. Radical innovation breakthroughs of plastic biodegradation have been initiated since the discovery of biodegradation of plastics by Tenebrio molitor larvae in 2015 followed by Galleria mellonella in 2017. Here we review updated studies on the insect-mediated biodegradation of plastics. Plastic biodegradation by insect larvae, mainly by some species of darkling beetles (Tenebrionidae) and pyralid moths (Pyralidae) is currently a highly active and potentially transformative area of research. Over the past eight years, publications have increased explosively, including discoveries of the ability of different insect species to biodegrade plastics, biodegradation performance, and the contribution of host and microbiomes, impacts of polymer types and their physic-chemical properties, and responsible enzymes secreted by the host and gut microbes. To date, almost all major plastics including polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polyurethane (PUR), and polystyrene (PS) can be biodegraded by T. molitor and ten other insect species representing the Tenebrionidae and Pyralidae families. The biodegradation processes are symbiotic reactions or performed by synergistic efforts of both host and gut-microbes to rapidly depolymerize and biodegrade plastics with hourly half-lives. The digestive ezymens and bioreagents screted by the insects play an essential role in plasatic biodegradation in certain species of Tenebrionidae and Pyralidae families. New research on the insect itself, gut microbiomes, transcriptomes, proteomes and metabolomes has evaluated the mechanisms of plastic biodegradation in insects. We conclude this review by discussing future research perspectives on insect-mediated biodegradation of plastics.

The construction of a navigation system plays an important role in the development of national politics,economy and military affairs.Nowadays,the Beidou navigation system is facing a transition period from the regional navigation system to the global one.For the global constellation,the system performance will not be seriously degraded when one or two satellites are invalid,but it is out of case for the regional constellation,which usually has fewer satellites and less redundancy.This paper deals with this problem of hybrid constellations and analyzes the influence of the disabled satellites on the system.With hybrid constellations and simulation methods designed,the influence of invalid satellites on the navigation system is fully investigated.

The interaction of p-d orbitals at bimetallic sites plays a crucial role in determining the catalytic reactivity, which facilitates the modulation of charges and enhances the efficiency of CO 2 electroreduction process. Here, we show a ligand co-etching approach to create asymmetric Zn-Sn dual-atom sites (DASs) within metal-organic framework (MOF)-derived yolk-shell carbon frameworks (named Zn 1 Sn 1 /SNC). The DASs comprise one Sn center ( p -block) partially doped with sulfur and one Zn center ( d -block) with N coordination, facilitating the coupling of p-d orbitals between the Zn-Sn dimer. The N-Zn-Sn-S/N arrangement displays an asymmetric distribution of charges and atoms, leading to a stable adsorption configuration of HCOO* intermediates. In H-type cell, Zn 1 Sn 1 /SNC exhibits an impressive formate Faraday efficiency of 94.6% at -0.84 V. In flow cell, the asymmetric electronic architecture of Zn 1 Sn 1 /SNC facilitates high accessibility, leading to a high current density of -315.2 mA cm -2 at -0.90 V. Theoretical calculations show the asymmetric sites in Zn 1 Sn 1 /SNC with ideal adsorption affinity lower the CO 2 reduction barrier, thus improve the overall efficiency of CO 2 reduction. The electrocatalytic reduction of CO 2 to high-value products through local coordination environment regulation of metal centers is important. Here, the authors demonstrate an asymmetric Zn-Sn dual atom sites catalyst with d-p orbital hybridization thereby achieving high formate selectivity.

Regioselective arene C−H bond alkylation is a powerful tool in synthetic chemistry, yet subject to many challenges. Herein, we report the meta -C−H bond alkylation of aromatics bearing N -directing groups using (hetero)aromatic epoxides as alkylating agents. This method results in complete regioselectivity on both the arene as well as the epoxide coupling partners, cleaving exclusively the benzylic C−O bond. Oxetanes, which are normally unreactive, also participate as alkylating reagents under the reaction conditions. Our mechanistic studies reveal an unexpected reversible epoxide ring opening process undergoing catalyst-controlled regioselection, as key for the observed high regioselectivities. Regioselective arene C−H bond alkylation is a powerful tool in synthetic chemistry, yet subject to many challenges. Here, the authors report the meta-C−H bond alkylation of aromatics bearing N-directing groups using (hetero)aromatic epoxides as alkylating agents.

Architected materials that consist of multiple subelements arranged in particular orders can demonstrate a much broader range of properties than their constituent materials. However, the rational design of these materials generally relies on experts’ prior knowledge and requires painstaking effort. Here, we present a data-efficient method for the high-dimensional multi-property optimization of 3D-printed architected materials utilizing a machine learning (ML) cycle consisting of the finite element method (FEM) and 3D neural networks. Specifically, we apply our method to orthopedic implant design. Compared to uniform designs, our experience-free method designs microscale heterogeneous architectures with a biocompatible elastic modulus and higher strength. Furthermore, inspired by the knowledge learned from the neural networks, we develop machine-human synergy, adapting the ML-designed architecture to fix a macroscale, irregularly shaped animal bone defect. Such adaptation exhibits 20% higher experimental load-bearing capacity than the uniform design. Thus, our method provides a data-efficient paradigm for the fast and intelligent design of architected materials with tailored mechanical, physical, and chemical properties. Architected materials can have enhanced properties compared to bulk but are difficult to design. Here the authors propose a machine-learning-based pipeline to design architected materials with predetermined elastic modulus and enhanced yield strength and test it in additive manufacturing.

Wireless technologies-supported printed flexible electronics are crucial for the Internet of Things (IoTs), human-machine interaction, wearable and biomedical applications. However, the challenges to existing printing approaches remain, such as low printing precision, difficulty in conformal printing, complex ink formulations and processes. Here we present a room-temperature direct printing strategy for flexible wireless electronics, where distinct high-performance functional modules (e.g., antennas, micro-supercapacitors, and sensors) can be fabricated with high resolution and further integrated on various flat/curved substrates. The additive-free titanium carbide (Ti 3 C 2 T x ) MXene aqueous inks are regulated with large single-layer ratio (>90%) and narrow flake size distribution, offering metallic conductivity (~6, 900 S cm −1 ) in the ultrafine-printed tracks (3 μm line gap and 0.43% spatial uniformity) without annealing. In particular, we build an all-MXene-printed integrated system capable of wireless communication, energy harvesting, and smart sensing. This work opens a door for high-precision additive manufacturing of printed wireless electronics at room temperature. High-precision printing of flexible wireless electronics has not been achieved before. Here, the authors leverage a room-temperature direct printing strategy to realize an all-MXene-printed integrated system capable of wireless communication, energy harvesting, and smart sensing.

Anxiety is a negative emotional state that is overly displayed in anxiety disorders and depression. Although anxiety is known to be controlled by distributed brain networks, key components for its initiation, maintenance and coordination with behavioral state remain poorly understood. Here, we report that anxiogenic stressors elicit acute and prolonged responses in glutamatergic neurons of the mouse medial preoptic area (mPOA). These neurons encode extremely negative valence and mediate the induction and expression of anxiety-like behaviors. Conversely, mPOA GABA-containing neurons encode positive valence and produce anxiolytic effects. Such opposing roles are mediated by competing local interactions and long-range projections of neurons to the periaqueductal gray. The two neuronal populations antagonistically regulate anxiety-like and parental behaviors: anxiety is reduced, while parenting is enhanced and vice versa. Thus, by evaluating negative and positive valences through distinct but interacting circuits, the mPOA coordinates emotional state and social behavior. Zhang et al. show in mice that the medial preoptic area antagonistically regulates stress-induced anxiety and parental behaviors, coordinated by opposing roles of its glutamatergic and GABAergic neurons through their competitive interactions.