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Lipids play crucial roles in many biological processes. Mapping spatial distributions and examining the metabolic dynamics of different lipid subtypes in cells and tissues are critical to better understanding their roles in aging and diseases. Commonly used imaging methods (such as mass spectrometry-based, fluorescence labeling, conventional optical imaging) can disrupt the native environment of cells/tissues, have limited spatial or spectral resolution, or cannot distinguish different lipid subtypes. Here we present a hyperspectral imaging platform that integrates a Penalized Reference Matching algorithm with Stimulated Raman Scattering (PRM-SRS) microscopy. Using this platform, we visualize and identify high density lipoprotein particles in human kidney, a high cholesterol to phosphatidylethanolamine ratio inside granule cells of mouse hippocampus, and subcellular distributions of sphingosine and cardiolipin in human brain. Our PRM-SRS displays unique advantages of enhanced chemical specificity, subcellular resolution, and fast data processing in distinguishing lipid subtypes in different organs and species. Spatial imaging methods in lipid research can disrupt tissue integrity and can have limited spatial and spectral resolution. Here, the authors present an SRS-based hyperspectral imaging platform to visualise lipids and lipoproteins in a variety of tissues and animal species. [ABSTRACT FROM AUTHOR]

Local dry underwater backward median pulse MIG welding (LDU-BMPMIG) was proposed in this study. The effects of different backward median currents on welding process stability, weld forming, microstructure, and mechanical properties of weldments were investigated comprehensively. The results reveal that the backward median current waveform effectively improved the welding stability. By calculating the approximate entropy of the voltage signal during welding, it is proved that the welding stability increases first and then decreases with the increase of the backward median current. The welding process stability was the most satisfied with the backward median current of 200 A. The quality of weld formation was consistent with welding stability. LDU-BMPMIG weldments exhibited fewer macroscopic defects and better overall morphology compared with LDU-PMIG weldment. The weldment microstructure was mainly composed of γ-austenite and δ-ferrite with different morphologies. The satisfied stability of the welding process contributed to improving the microstructure uniformity. The variation trend of tensile strength for LDU-BMPMIG weldments was approximately kept consistent with welding process stability. The weldment prepared by 200 A showed considerable mechanical properties with minimal fluctuation, which reached 97.58% of maximum average tensile strength, which meant the most excellent compared to the others. The experimental results can improve the stability of local dry underwater welding and provide a theoretical basis and technical support for the application of underwater welding. [ABSTRACT FROM AUTHOR]

The oil-paper insulation of high-frequency (HF) transformers frequently withstands high-frequency over-voltages at frequencies of several kHz and above. This leads to the occurrence of partial discharge (PD), which causes premature insulation failure in HF transformers. In order to investigate the effect of PD under high-frequency stresses on oil-impregnated Nomex paper, this paper analyzes the surface morphology, bond-broken types of the molecular chain, and product types formed for oil paper after PD degradation. Then, the damage mechanism of oil-immersed Nomex paper between high-frequency and AC stress is explored. The experimental results show that the branches of creepage do not exist in the oil-paper insulation during the entire discharge process under high-frequency stresses, and that their damage degree is higher than that of AC stress. This is mainly because the benzene ring of oil-impregnated Nomex paper is destroyed and opened caused by high-energy particles, the heating effect in HF discharge, and the bulk effect. These results help to improve the design theory of insulation structures and to develop PD-resistant insulation materials in HF transformers. [ABSTRACT FROM AUTHOR]

304 stainless steel, which is widely used in the industrial field due to its excellent thermostability, corrosion resistance, and welding performance, was welded using local dry underwater pulse metal inert gas (LDU-PMIG) welding technology in this study. The effect of different pulse peak currents on droplet transfer behavior and weld formation was investigated. The results show that short circuit transfer, globular transfer, and projected transfer were observed in the LDU-PMIG process. With the peak current of 240 A, the droplet transfer modes were short-circuit transfer and globular transfer; the weld formation was irregular with large particle spatters around the weld. With the peak current increased to 260 A, the droplet transfer mode changed into the globular transfer, and the weld formation quality was improved. With the peak current of 280 A, the droplet transfer mode was projected transfer, the weld formation was satisfied with a few spatters, and the coefficient of weld formation was the largest, and projected transfer was the most stable mode. With the increase of the peak current from 300 to 320 A, the droplet transfer mode did not change, but the instability of the welding arc resulted in poor weld formation with serious spatters and undercuts. [ABSTRACT FROM AUTHOR]

The ability of superabsorbent polymers (SAPs) to absorb and retain a large amount of aqueous solution enables their applications in agriculture, medicine and water treatment. As a result, there were numerous studies reporting the present status and application prospects of raw materials and the mechanism of cross-linking agents. Conversely, there was a lack of research on the factors affecting SAP performance and the summaries of methods to improve performance. In this paper, a comprehensive and systematic review based on the structure and water absorption mechanism of SAPs was performed. The methods of improving the performance and main factors of the synthesis of SAPs, such as monomer, cross-linking agent, initiator, ion concentration, hydrophilic group, neutralization degree and particle size, were discussed. The improvement methods of salinity tolerance, reusability, water absorption and rate of SAP were explored. In addition, some applications and future research in SAPs are also discussed in this review. [ABSTRACT FROM AUTHOR]

Thermosets—polymeric materials that adopt a permanent shape upon curing—have a key role in the modern plastics and rubber industries, comprising about 20 per cent of polymeric materials manufactured today, with a worldwide annual production of about 65 million tons1,2. The high density of crosslinks that gives thermosets their useful properties (for example, chemical and thermal resistance and tensile strength) comes at the expense of degradability and recyclability. Here, using the industrial thermoset polydicyclopentadiene as a model system, we show that when a small number of cleavable bonds are selectively installed within the strands of thermosets using a comonomer additive in otherwise traditional curing workflows, the resulting materials can display the same mechanical properties as the native material, but they can undergo triggered, mild degradation to yield soluble, recyclable products of controlled size and functionality. By contrast, installation of cleavable crosslinks, even at much higher loadings, does not produce degradable materials. These findings reveal that optimization of the cleavable bond location can be used as a design principle to achieve controlled thermoset degradation. Moreover, we introduce a class of recyclable thermosets poised for rapid deployment. A method of endowing thermoset plastics with a degree of recyclability and reprocessability by incorporating cleavable chemical linkages in the strands of the polymer, rather than in the crosslinks, is presented. [ABSTRACT FROM AUTHOR]

The aim is to study the characteristics of dual-net and dual-protection configuration of 750 kV substation and take into consideration the uncertainty of the substation, such as maloperation and rejection miss trip of protection and breaker. This paper proposed a diagnosis fault method with redundancy based on fuzzy Petri net in a framework of multi-agent system. The reasoning model is divided into global agent layer, local agent layer, and connected agent layer according to multi-agent hierarchical method, and the fault region and suspicious fault component are determined by the former two layer based on case information. The restriction and rule are formed by topological structure and protection configuration of grid. This algorithm adopts the information entropy to determine the credibility of initial information, the model of fuzzy Petri is established in the third layer and divided into main network and redundant network to carry out the sub-network, and then the diagnosis result with minimum uncertainty is obtained by fuzzy reasoning. The simulation results show this model has higher accuracy and better fault tolerance ability. [ABSTRACT FROM AUTHOR]

The low-complexity channelizer is essential in passive radar multi-channel wideband receiver using array antennas. The digital filter bank is usually used to realize the channelizer. In the paper, a low-complexity channelizer based on frequency response masking (FRM) is proposed to reduce the high computational complexity of the narrow transition bandwidth filter bank. A half-band filter is used to design the prototype filter of the proposed low-complexity channelizer based on FRM. Compared to the maximally decimated filter bank, the decimation coefficient of the non-maximally decimated filter bank can be different from the number of channels, which makes the low-complexity channelizer more flexible. The low-complexity channelizer based on FRM can be directly applied to a wideband receiver without the limit of the sampling rate. The simulation and complexity analysis results show that the proposed low-complexity channelizer is correct and significantly reduces computational and hardware complexities. The proposed low-complexity channelizer makes it possible to implement passive radar multi-channel wideband receiver on a single hardware processor; thus, it is suitable to applied in passive radar multi-channel wideband receiver using array antennas. [ABSTRACT FROM AUTHOR]

Modulated filter bank with low complexity is the key to realize the engineering applications for speech signal processing, multicarrier communication, and wideband digital receivers. The frequency response masking (FRM) technology is an effective method to design finite impulse response filters with narrow transition band (NTB). In this paper, an interpolation FRM unified modulated filter bank (IFRM-UMFB) architecture with NTB is proposed to reduce the computational complexity of the modulated filter bank architecture. The IFRM approach increases the transition band of two masking filters by the interpolation of N and reduces the computational complexity of two masking filters compared with classic FRM approach. The proposed IFRM-UMFB architecture with NTB is suitable for different odd-stacked or even-stacked, maximally decimated or non-maximally decimated structures. The proposed IFRM-UMFB architecture with NTB is verified to be correct through simulation. The complexity comparison result shows that the proposed IFRM-UMFB architecture offers multipliers reduction of 77.4% over the directly design approach and 26.5% over the classic FRM approach. Moreover, the proposed IFRM-UMFB architecture with NTB also can be directly applied to wideband digital receivers with high sampling rate. [ABSTRACT FROM AUTHOR]

Aiming at the locality and uncertainty of observations in large-scale multi-agent application scenarios, the model of Decentralized Partially Observable Markov Decision Processes (DEC-POMDP) is considered, and a novel multi-agent reinforcement learning algorithm based on local communication is proposed. For a distributed learning environment, the elements of reinforcement learning are difficult to describe effectively in local observation situation, and the learning behaviour of each individual agent is influenced by its teammates. The local communication with consensus protocol is utilized to agree on the global observing environment, and thus that a part of strategies generated by repeating observations are eliminated, and the agent team gradually reach uniform opinion on the state of the event or object to be observed, they can thus approach a unique belief space regardless of whether each individual agent can perform a complete or partial observation. The simulation results show that the learning strategy space is reduced, and the learning speed is improved. [ABSTRACT FROM AUTHOR]

The two key requirements of channelized filter bank in the design of a digital receiver are low computational complexity and reconfigurability. Modulated discrete Fourier transform (MDFT) filter bank permits sub-channel with linear phase characteristics and provides high degree of computational efficiency. However, with sub-channel exhibiting narrow transition bandwidth in MDFT filter bank, the length of the prototype filter becomes long prohibitively, which can reduce the computational efficiency. It is well known that the frequency response masking (FRM) provides an attractive technique for the realization of digital filters with very narrow transition bandwidth. In this paper, the FRM digital filter design technique and another important technique named complex-exponential modulation (CEM) are exploited and applied to the design of a novel cascaded channelized filter bank to realize selective sub-channel with very narrow transition bandwidth. A simulation is provided to illustrate the design of the proposed CEM filter bank. It is shown that the resulting filter bank entails less computational complexity substantially and reduces multiplier resource consumption comparing to the conventional MDFT filter bank. [ABSTRACT FROM AUTHOR]

We have calculated the longitudinal acoustic phonon limited electron mobility of 14 two-dimensional semiconductors with composition of MX, where M (= Mo, W, Sn, Hf, Zr and Pt) is the transition metal, and X is S, Se and Te. We treated the scattering matrix by the deformation potential approximation. We found that out of 14 compounds, MoTe, HfSe and ZrSe are promising regarding to their possible high mobility and finite band gap. The phonon limited mobility can be above 2,500 cm·V·s at room temperature. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Aims: Rice is a well-known silica-accumulating plant. The dumbbell-shaped silica bodies in the silica cells in rice leaf epidermis are formed via biosilicification, but the underlying mechanisms are largely unknown. Methods: Leaves at different developmental stages were collected to investigate silica cell differentiation by analyzing structures and silicon localization in the silica cells. Results: Exogenous silicon application increased both shoot and root biomass. When silicon was supplied, silica cells in the leaf epidermis developed gradually into a dumbbell-shape and became increasingly silicified as leaves aged. Silicon deposition in the silica cells was not completed until the leaf was fully expanded. Multiple lines of evidence suggest that lignification of silica cell walls precedes silicon deposition in the lumen of silica cells. The organized needle-like silica microstructures were formed by moulding the inner cell walls and filling up the lumen of the silica cell following leaf maturation. Conclusions: Two processes were involved in silicon deposition: (1) the silica cell wall was lignified and silicified, and then (2) the silicon was deposited gradually in silica cells as leaves aged. Silica body formation was not completed until the leaf was fully mature. [ABSTRACT FROM AUTHOR]

M-type barium ferrite thin films with hexagonal platelets on sapphire were fabricated by spin-coating of precursors. Fourier-transform infrared spectra indicated that bonds between the metal and oxygen were formed at about 500°C. X-ray diffraction showed that the films had preferred c-axis orientation. Surface morphology of the film was investigated by scanning electron microscopy. Textures of the films were influenced by the amount of ethylenediamine tetraacetic acid (EDTA). The film with the least pores and the most c-axis-textured platelet hexagonal grains was obtained when the ratio of EDTA to metal ions was 1.0. At the same time, the magnetic hysteresis loops in directions parallel and perpendicular to the film plane demonstrated that the films were almost isotropic. The maximum coercive forces of 43.23 kA/m in plane and 54.70 kA/m out of plane were achieved when the ratio of the amount of EDTA to metal ions was 0.5. The highest in-plane remanence ratio was 0.32 when the ratio of EDTA to metal ions was 1.5, while the highest out-of-plane value was 0.28 in the other two cases. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

A versatile two-dimensional (2D) molecular bilayer heterostructure of asymmetric MXene/monolayer transition metal dichalcogenide (aMXene/mTMDC) with a high interfacial built-in electric field is here simulated, where aMXene is an aMXene with the top or bottom electronegative atom plane of MXene removed. The asymmetric structural design of aMXene leads to a high dipole moment perpendicular to the 2D molecular plane. Although the unpassivated metal atoms in the aMXene are unstable and electropositive, coupling them to the electronegative chalcogenide atoms in an aMXene/mTMDC bilayer resolves this deficiency. The dipole field tunable by the specific composition of aMXene/mTMDC is leveraged to engineer unusual band structures, band alignments, and charge redistribution/injection in the bilayer. The simulated design of several aMXene/mTMDC bilayers for possible use in spintronics, microelectronics/optoelectronics, and catalysis/photocatalysis are shown. [ABSTRACT FROM AUTHOR]

The distribution of carbon from a branch setting pod in alfalfa was investigated during the seed development of seeds to determine the relative contribution of pod and leaf photoassimilates to the total C balance and to investigate the partitioning of these photoassimilates to other plant organs. A 13Clabeling procedure was used to label C photoassimilates of pods and leaves in alfalfa, and the Δ13C values of a pod, leaves, a section of stem and roots were measured during seed development on day 10, 15, 20 and 25 after labeling of the pod. The results showed that the alfalfa pod had photosynthetic capacity early in the development of seeds, and that pod photosynthesis could provide carbon to alfalfa organs including seeds, pods, leaves, stems and roots, in addition to leaf photosynthesis. Photosynthesis in the pod affected the total C balance of the alfalfa branch with the redistribution of a portion of pod assimilates to other plant organs. The assimilated 13C of the pod was used for the growth requirements of plant seeds and pods. The requirements for assimilated C came primarily from the young pod in early seed development, with later requirements provided primarily from the leaf. [ABSTRACT FROM AUTHOR]