Search

Bioinspired polarized skylight navigation, which can be used in unfamiliar territories, is an important alternative autonomous navigation technique in the absence of Global Navigation Satellite System (GNSS). However, the polarization pattern in night environment with noise effects and model uncertainties is a less explored area. Although several decades have passed since the first publication about the polarization of the moonlit night sky, the usefulness of nocturnal polarization navigation is only sporadic in previous researches. This study demonstrates that the nocturnal polarized light is capable of providing accurate and stable navigation information in dim light outdoor environment. Based on the statistical characteristics of Angle of Polarization (AoP) error, a probability density estimation method is proposed for heading determination. To illustrate the application potentials, the simulation and outdoor experiments are performed. Resultingly, the proposed method robustly models the distribution of AoP error and gives accurate heading estimation evaluated by Standard Deviation (STD) which is 0.32° in a clear night sky and 0.47° in a cloudy night sky.

In this paper, we study a (3+1)-dimensional generalized shallow water wave equation with variable coefficients, which describes the flow below a pressure surface in a fluid. We give the Kadomtsev-P...

For a coupled nonlinear Schrodinger system with the negative coherent coupling, which describes two orthogonally polarized pulses in a weakly birefringent fibre, we construct the Darboux dressing t...

Converting biomass waste into high-value products presents a challenging task in the environmental field. Growth of graphene from solid-state precursors is cost-effective and is becoming a hot research topic. However, the underlying mechanisms are as yet unclear. In this work, we report a novel method for directly growing adlayer-free large area graphene from cellulose acetate, the main component of cigarette filter waste. The evolution of cellulose acetate to reduced graphene oxide and finally to graphene is shown in this work for the first time. The effect of various growth parameters, hydrogen concentration and Cu grain boundaries on the size and qualities of the monolayer graphene domains is clarified. Finally, the mechanism for the growth of graphene from a solid-state precursor is proposed. The field-effect-transistor fabricated from transferred monolayer graphene demonstrated high electron and hole mobilities ∼1500 cm2/(V·s). This work presents a new opportunity for converting biomass waste into high-value graphene products.

Salt marshes provide crucial ecological functions and services and are experiencing rapid losses and degradation under global climate changes and high-intensity human activities in coastal zone. However, mapping salt marsh distributions and compositions with high accuracy on the national or global scale remains challenging. Here, we used Sentinel-1 time-series data and knowledge-based automatic decision tree classifiers to produce a 10-m map of the salt marshes in China coastal zones. We established annual synthetic aperture radar (SAR) composite features to address seasonal variations and tidal dynamics in salt marshes and created five partitioned-region classifiers according to the climatic and environmental characteristics. In total, 1729 Sentinel-1 images in 2019 and 3418 in situ sites were included for the classification. The results showed that (1) the annual mean SAR composite is more stable and practical than the seasonal composite for salt marsh classification along the China coastal zones in terms of these features addressing variations in tidal fluctuation, climate zones, and salt marsh compositions; (2) SAR surface roughness can effectively separate salt marshes into sparse density and red phenotype salt marshes; (3) the total area of Chinese coastal salt marshes was 127,477.37 ha with an overall accuracy of 87.30%, it included 48.30% Spartina alterniflora, 29.19% Phragmites australis, 13.76% Suaeda spp. and 8.75% Scirpus spp., and more than 85% of salt marshes were distributed from Shandong Province to Zhejiang Province. This study showed the potential application of time-series Sentinel-1 SAR data, annual composite data and knowledge-based classifiers for large-scale coastal zones, and these data will be valuable for coastal ecological restoration and sustainability management.

In the process of cold tandem rolling, chatter instability leads to serious impacts on enhancing rolling speed, improving product quality, reducing production cost and realizing intellectualization. Chatter occurs with the rolling speed up to a certain threshold value, but the critical speed is determined by both product specifications and rolling schedules. A 5-stand cold tandem rolling mill whose first three stands and subsequent two stands, respectively, have four and six rolls was investigated by formulating its dynamic equations with the corresponding structure–process coupling. By applying the stability-based calculation model about the critical rolling speed in each stand, the system dynamic responses around the critical rolling speed were simulated, and the system eigenvalues which represent instability and characteristic frequencies were figured out. Thereafter, via combining the critical rolling speeds with the system dynamic behavior, a dynamics-based optimization model of rolling schedule for the 5-stand cold tandem system was proposed for the purposes of both the chatter suppression and rolling speed increase. In the optimization model, eight rolling technique parameters (four strip thicknesses and four tensions between the upstream and downstream stands) were taken as design variables, and the constraint conditions were set as no chatter instability in all five stands, and the optimization goal was to maximize the outlet speed of the final stand. The pattern search method was introduced to solve the optimization model. By applying such a dynamics-based optimization model for the 5-stand cold tandem rolling process, the chatter instability was suppressed effectively and the rolling efficiency was improved considerably; therefore, such an optimization model is expected to be valuable for intelligent manufacturing of rolling process.

Nervonic acid (NA, cis-15-tetracosenoic acid) is a very long-chain monounsaturated fatty acid that has been shown to be a core component of nerve fibers and nerve cells. It can be used to treat and prevent many neurological diseases. At present, commercially available NA is mainly derived from Acer truncatum seeds, which contain about 5%–6% NA in their seed oil. The aim of this study were to identify and analyze NA-containing Acer species that could be used as NA resource plants. For this purpose, 46 Acer species seeds were collected in China and in some or all of the seed oils from these species 15 fatty acids were detected, including linoleic acid, oleic acid (C18:1Δ9, C18:1Δ11), erucic acid, palmitic acid, NA, linolenic acid (C18:3Δ6,9,12, C18:3Δ9,12,15), eicosenoic acid (C20:1Δ11, C20:1Δ13), stearic acid, behenic acid, tetracosanoic acid, arachidic acid, and docosadienoic acid. Nervonic acid was detected in all samples, but the content was highly variable among species. NA content over 9% was detected in eleven species, of which Acer elegantulum had the highest levels (13.90%). The seed oil content, seed weight, and fatty acid profiles varied among species, but the comprehensive evaluation value (W) showed that A. coriaceifolium could be a new potential NA resources plant. The results also showed that NA was significantly negatively correlated with palmitic acid, oleic acid, and eicosenoic acid, but positively correlated with eicosadienoic acid, behenic acid, erucic acid, and tetracosanoic acid, which indicate the probable pathway for NA biosynthesis in Acer plants. This study has identified Acer species that may serve as NA resources and will help guide subsequent species breeding programs.

In this paper, outcomes of the study on the Backlund transformation, Lax pair, and interactions of nonlinear waves for a generalized (2 + 1)-dimensional nonlinear wave equation in nonlinear optics, fluid mechanics, and plasma physics are presented. Via the Hirota bilinear method, a bilinear Backlund transformation is obtained, based on which a Lax pair is constructed. Via the symbolic computation, mixed rogue–solitary and rogue–periodic wave solutions are derived. Interactions between the rogue waves and solitary waves, and interactions between the rogue waves and periodic waves, are studied. It is found that (1) the one rogue wave appears between the two solitary waves and then merges with the two solitary waves; (2) the interaction between the one rogue wave and one periodic wave is periodic; and (3) the periodic lump waves with the amplitudes invariant are depicted. Furthermore, effects of the noise perturbations on the obtained solutions will be investigated.

Production of hydroxy fatty acids (HFAs) in transgenic crops represents a promising strategy to meet our demands for specialized plant oils with industrial applications. The expression of Ricinus communis (castor) OLEATE 12-HYDROXYLASE (RcFAH12) in Arabidopsis has resulted in only limited accumulation of HFAs in seeds, which probably results from inefficient transfer of HFAs from their site of synthesis (phosphatidylcholine; PC) to triacylglycerol (TAG), especially at the sn-1/3 positions of TAG. Phospholipase As (PLAs) may be directly involved in the liberation of HFAs from PC, but the functions of their over-expression in HFA accumulation and distribution at TAG in transgenic plants have not been well studied. In this work, the functions of lecithin:cholesterol acyltransferase-like PLAs (LCAT-PLAs) in HFA biosynthesis were characterized. The LCAT-PLAs were shown to exhibit homology to LCAT and mammalian lysosomal PLA2 , and to contain a conserved and functional Ser/His/Asp catalytic triad. In vitro assays revealed that LCAT-PLAs from the HFA-accumulating plant species Physaria fendleri (PfLCAT-PLA) and castor (RcLCAT-PLA) could cleave acyl chains at both the sn-1 and sn-2 positions of PC, and displayed substrate selectivity towards sn-2-ricinoleoyl-PC over sn-2-oleoyl-PC. Furthermore, co-expression of RcFAH12 with PfLCAT-PLA or RcLCAT-PLA, but not Arabidopsis AtLCAT-PLA, resulted in increased occupation of HFA at the sn-1/3 positions of TAG as well as small but insignificant increases in HFA levels in Arabidopsis seeds compared with RcFAH12 expression alone. Therefore, PfLCAT-PLA and RcLCAT-PLA may contribute to HFA turnover on PC, and represent potential candidates for engineering the production of unusual fatty acids in crops.

Biomass transformation is being considered as a green and sustainable strategy for carbon-based functional materials in many fields. To produce porous structure favorable for microwave absorption, we demonstrate herein the successful synthesis of macroporous carbon materials with cornstalk as a biomass precursor. It is found that two kinds of typical biological structures in cornstalk, linear vascular bundles and parenchyma cells, can be well preserved during high-temperature pyrolysis. Mercury intrusion porosimetry and N2 adsorption indicate that these cornstalk-derived carbon materials have very high porosity, which is mainly from desirable macroporous structure rather than conventional micro/mesopores. Electromagnetic (EM) analysis reveals that dielectric loss is the only pathway for the consumption of EM energy, and high pyrolysis temperature favors strong dielectric loss through conductive loss and interfacial polarization loss. Meanwhile, pyrolysis temperature also affects the matching degree of characteristic impedance. When the pyrolysis temperature reaches 750 °C, good dielectric loss and impedance matching endow the sample (CSC-750) with excellent microwave absorption performance, including strong reflection loss, broad response bandwidth, and relatively thin absorber thickness. The advantages of macroporous structure are further highlighted in impedance matching and multiple reflection by comparing with a macropore-free counterpart.

Investigation is conducted on a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid mechanics and plasma physics. By virtue of the homoclinic-test, ansatz and polynomial-expansio...

Due to the complexity and variability of the cellular metabolic process and the physiological environment inside and outside the cell, higher requirements are needed on the application of DNA molecular logic gate in cell analysis. In addition, heterogeneity of tumor cells tends to lead to false positives in the clinical diagnosis of a single target, even those with the same cancer type. To address these issues above, we have developed a novel DNA molecular logic gate responsive nanomachine for bispecific recognition and computation of cell membranes. Only when two membrane proteins, MUC1 and EpCAM as model proteins, exist simultaneously, the DNA molecular logic gate can be activated to perform "AND" logic operation and generate amplified "ON" fluorescence signal from the cell membrane. Therefore, our proposed dual-specific "recognition-biocomputing" DNA molecular logic gate has achieved highly accurate imaging analysis of dual-target membrane proteins in situ. Furthermore, the logic gate responsive DNA nanomachine can also be used to analyze target cells in complex cell samples with excellent specificity, which will meet the needs of biomedicine and their application in clinical diagnosis and provide new tools for the biomedical application of DNA molecular logic gates in complex cell systems.

Non-Kerr media possess certain applications in photonic lattices and optical fibers. Studied in this paper are the vector rational and semi-rational rogue waves in a non-Kerr medium, through the coupled cubic-quintic nonlinear Schrodinger system, which describes the effects of quintic nonlinearity on the ultrashort optical pulse propagation in the medium. Applying the gauge transformations, we derive the Nth-order Darboux transformation and Nth-order vector rational and semi-rational rogue wave solutions, where N is a positive integer. With such solutions, we present three types of the second-order rogue waves with the triangle structure: the one with each component containing three four-petaled rogue waves, the one with each component containing three eye-shaped rogue waves, and the other with one component containing three anti-eye-shaped rogue waves and the other component containing three eye-shaped rogue waves. We exhibit the third-order vector rogue waves with the merged, triangle and pentagon structures in each component. Moreover, we show the first- and second-order vector semi-rational rogue waves which display the coexistence of the rogue waves and the breathers.

BCL-2 gene as well as its products is recognized as a promising target for the molecular targeted therapy of tumors. However, due to certain defense measures of tumor cells, the therapeutic effect based on the gene silencing of BCL-2 is greatly reduced. Here we fabricate a smart response nucleic acid therapeutic that could silence the gene effectively through a dual-targeted and cascade-enhanced strategy. In brief, nano-graphene oxide (GO), working as a nano-carrier, is loaded with a well-designed DNAzyme, which can target and silence the BCL-2 mRNA. Furthermore, upon binding with the BCL-2 mRNA, the enzymatic activity of the DNAzyme can be initiated, cutting a substrate oligonucleotide to produce an anti-nucleolin aptamer AS1411. Nucleolin, a nucleolar phosphoprotein, is known as a stabilizer of BCL-2 mRNA. Via binding and inactivating the nucleolin, AS1411 can destabilize BCL-2 mRNA. By this means of simultaneously targeting mRNA and its stabilizer in an integrated system, effective silencing of the BCL-2 gene of tumor cells is achieved at both the cellular and in vivo levels. After being dosed with this nucleic acid therapeutic and without any chemotherapeutics, apoptosis of tumor cells at the cellular level and apparent shrinkage of tumors in vivo are observed. By labeling a molecular beacon on the substrate of DNAzyme, visualization of the enzymatic activity as well as the tumor in vivo can be also achieved. Our work presents a pure bio-therapeutic strategy that has positive implications for enhancing tumor treatment and avoiding side effects of chemotherapeutics.

Among the patterning technologies for organic thin-film transistors (OTFTs), the fabrication of OTFT electrodes using polymer templates has attracted much attention. However, deviations in the electrode alignment occur because the coefficient of thermal expansion (CTE) of the polymer template is much higher than the CTE of the dielectric layer. Here, a novel dry-blending method is described in which SiO2 nanoparticles are filled into a grooved silicon template, followed by permeation of polydimethylsiloxane (PDMS) into the SiO2 nanoparticle gaps. The SiO2 nanoparticles in the groove are extracted by curing and peeling off PDMS to prepare a PDMS/SiO2 composite template with a nanoparticle content of 83.8 wt %. The composite template has a CTE of 96 ppm/°C, which is a reduction by 69.23% compared with the original PDMS template. Finally, we achieved the alignment of OTFT electrodes using the composite template.

Detection of a single base mutation in Mycobacterium tuberculosis DNA can provide fast and highly specific diagnosis of antibiotic-resistant tuberculosis. Mutation-specific ligation of padlock probes (PLPs) on the target followed by rolling circle amplification (RCA) is highly specific, but challenging to integrate in a simple microfluidic device due to the low temperature stability of the phi29 polymerase and the interference of phi29 with the PLP annealing and ligation. Here, we utilized the higher operation temperature and temperature stability of Equiphi29 polymerase to simplify the integration of the PLP ligation and RCA steps of an RCA assay in two different strategies performed at uniform temperature. In strategy I, PLP annealing took place off-chip and the PLP ligation and RCA were performed in one pot and the two reactions were clocked by a change of the temperature. For a total assay time of about 1.5 h, we obtained a limit of detection of 2 pM. In strategy II, the DNA ligation mixture and the RCA mixture were separated into two chambers on a microfluidic disc. After on-disc PLP annealing and ligation, the disc was spun to mix reagents and initiate RCA. For a total assay time of about 2 h, we obtained a limit of detection of 5 pM. Graphical abstract.

Under investigation in this paper is a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid mechanics and plasma physics. With the help of symbolic computation, we obtain and disc...

Bifacial dye-sensitized solar cells (DSSCs) are regarded as promising solar energy conversion devices with high efficiency and less resource consumption. In this work, a highly transparent and efficient counter electrode (CE) is fabricated by introducing highly dispersed single Pt atoms doped into the van der Waals layer-by-layer epitaxially grown Zn-TCPP thin film (Zn-TCPP-Pt). The resulting Zn-TCPP-Pt CE has similar catalytic activity to commercial Pt CE but shows a better light transmission capacity in the range of visible light. The bifacial DSSC with Zn-TCPP-Pt thin film CE achieves high power conversion efficiencies of 5.48 and 4.88% under front-side and rear-side irradiation, respectively. With maximized atomic efficiency, excellent performance was obtained with about 1% Pt content and highly transparent CEs. Therefore, the light energy resource utilization rate of such less Pt and transparence CE is greatly improved in bifacial dye-sensitized solar cells, making it a promising candidate to replace Pt CE.

Optical fiber communication becomes one of the main pillars of modern communication. In this paper, we study a coupled nonlinear Schrodinger system with variable coefficients, which can describe the simultaneous propagation of the M-field components in an inhomogeneous optical fiber, where M is a positive integer. When M = 2 , the bilinear forms are constructed with the Hirota method and the N-bright-dark soliton solutions in terms of the Grammian can be obtained via the Kadomtsev-Petviashvili hierarchy reduction, where N is a positive integer. With the asymptotic analysis and graphic analysis, we find that the amplitudes of one-bright-dark solitons and the background in the dark components exhibit the periodic oscillations. Without the amplification/absorption effect, elastic interaction between the two-bright-dark solitons which keep both the amplitudes and the wave backgrounds invariant is demonstrated. Particularly, we find inelastic interaction between the two-bright-dark solitons, which possess the V-shape profiles in the zero background components and the Y-shape profiles in the periodic oscillating background components. The bound-state soliton under that inelastic condition is also shown. Besides, we present the bound-state bright-dark solitons with varying amplitudes. Furthermore, the analysis of the N-bright-dark soliton solutions are extended to those with M > 2, and as an example, inelastic interaction of the solitons with the case of M = 4 is presented.

Optical fiber communication system is one of the core supporting systems of the modern internet age. In this paper, under investigation is a variable-coefficient fourth-order nonlinear Schrodinger system, which describes the simultaneous propagation of the optical pulses in an inhomogeneous optical fiber. The first-order breathers are constructed. Breathers are converted into several types of the nonlinear waves, i.e., multi-peak solitons, antidark solitons, periodic waves and W-shaped solitons, under the transition condition. With the decrease of | λ r + a 2 | , the peak number of a multi-peak soliton increases, where λr represents the real part of the spectral parameter and a is a real constant. Peak number reaches the maximum since the multi-peak soliton is transformed into a set of the periodic waves with λ r + a 2 = 0 . Widths and velocities of the multi-peak solitons are related to the group velocity dispersion and fourth-order dispersion coefficients. We find that the condition of baseband modulational instability coincides with the transition condition when we use the rogue-wave eigenvalues, i.e., the transition between the rogue waves and multi-peak solitons can occur in the baseband modulational instability.

Offshore wind farms are widely adopted by coastal countries to obtain clean and green energy; their environmental impact has gained an increasing amount of attention. Although offshore wind farm datasets are commercially available via energy industries, records of the exact spatial distribution of individual wind turbines and their construction trajectories are rather incomplete, especially at the global level. Here, we construct a global remote sensing-based offshore wind turbine (OWT) database derived from Sentinel-1 synthetic aperture radar (SAR) time-series images from 2015 to 2019. We developed a percentile-based yearly SAR image collection reduction and autoadaptive threshold algorithm in the Google Earth Engine platform to identify the spatiotemporal distribution of global OWTs. By 2019, 6,924 wind turbines were constructed in 14 coastal nations. An algorithm performance analysis and validation were performed, and the extraction accuracies exceeded 99% using an independent validation dataset. This dataset could further our understanding of the environmental impact of OWTs and support effective marine spatial planning for sustainable development., Measurement(s) offshore wind turbine Technology Type(s) satellite imaging • digital curation Factor Type(s) temporal interval • spatial extent Sample Characteristic - Environment wind farm • atmospheric wind Sample Characteristic - Location global Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.14865690

In this paper, a (2+1)-dimensional generalized Hirota-Satsuma-Ito equation for the water waves is investigated. We obtain the N-soliton solutions according to the bilinear form. The M-lump solutions are obtained based on the N-soliton solutions, where N and M are the positive integers. We take $$M=2$$ and 3 to get the two- and three-lump solutions. Besides, three types of the hybrid solutions are discussed graphically, which contain the hybrid solutions between the one-lump wave and two-kink solitons, between the two-lump wave and one-kink soliton, and between the one-lump wave and breather wave.

Anthocyanins are vital components of plant secondary metabolites, and are also the most important coloring substances in wine. Teinturier cultivars are rich in anthocyanins. However, the differences in anthocyanin accumulation and profiles between teinturier and non-teinturier cultivars have not been reported. In this study, Yan 73 and Dunkelfelder were selected as the experimental materials, and three non-teinturier cultivars were used for comparison. LC-MS and qRT-PCR were used to determine the individual anthocyanin contents and the relative gene expression. The results show that the total anthocyanin content of the teinturier cultivars was considerably higher than that in non-teinturier cultivars, and the levels of individual anthocyanins increased gradually during ripening. Lower ratios of modified anthocyanins were found in the teinturier cultivars, which was not only due to the high expression level of VvUFGT and VvGST4, but also due to the relatively low expression of VvOMT in these cultivars. Cluster analysis of gene expression and anthocyanin accumulation showed that VvUFGT is related to anthocyanin accumulation, and that AM1 is related to the synthesis and transport of methylated anthocyanins. Our results will be useful for further clarifying the pathways of anthocyanin synthesis, modification, and transport in teinturier cultivars.

A (2+1)-dimensional extended Calogero–Bogoyavlenskii–Schiff system in nonlinear optics, fluid dynamics and plasma physics is investigated via the symbolic computation in this paper. Soliton solutions, which are kink-shaped, are obtained via the Hirota method. Breather solutions are derived via the extended homoclinic test approach, and lump solutions are obtained from the breather solutions under a limiting procedure. We find that the shape and amplitude of the one soliton keep unchanged during the propagation, and the velocity of one soliton depends on all the coefficients in the system. We graphically demonstrate that the interaction between the two solitons is elastic, and analyse the solitons with the influence of the coefficients. We observe that the amplitudes and shapes of the breather and lump remain unchanged during the propagation, and graphically present the breathers and lumps with the influence of the coefficients.

The Korteweg-de Vries (KdV)-type equations appear during the studies on the cosmic plasmas, planetary atmospheres and oceans. In this paper, via the Lie symmetry method, we investigate a three-coupled KdV system. Lie point symmetry generators and Lie symmetry groups are given. Based on the Lie point symmetry generators, the system is reduced to some ordinary differential systems. Applying the power-series, polynomial, Jacobi elliptic function and (G′/G) expansion methods on those reduced systems, we derive some group-invariant solutions including the explicit power-series, soliton, snoidal-wave and cnoidal-wave solutions. We graphically analyze the solitons and snoidal waves. Besides, we demonstrate the nonlinear self-adjointness of the system, based on which we present the conservation laws according to the Lie point symmetries.

Under investigation in this paper is a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid mechanics. We derive the mixed lump-stripe waves, bright mixed rogue wave-stripe, dark mixed rogue wave-stripe and dark rogue waves solutions by virtue of the symbolic computation. We observe the fission and fusion phenomena between the lump and one-stripe wave through the mixed-stripe wave solutions. Then, we observe that the influence of l1, l2, l3, l4, l5, l6, l7 and l8 on the mixed lump-stripe waves, where l1 and l2 represent the dispersion and nonlinear effects, l3, l6, l7 and l8 are the perturbed effects, while l4 and l5 stand for the disturbed wave velocities along the transverse spatial coordinates y and z, respectively. We graphically present the interaction between a rogue wave and a pair of stripe waves through the mixed rogue wave-stripe solutions. We derive a dark mixed rogue wave-stripe when l1

Complexes of proteins are central to certain cellular processes. Investigated in this paper is the three-coupled fourth-order nonlinear Schrodinger system, which is used for describing the alpha he...

Fluids are seen in a wide range of disciplines, including mechanical, civil, chemical and biomedical engineering, geophysics, astrophysics and biology. In this paper, we investigate a ( 3 + 1 ) -dimensional generalized Kadomtsev–Petviashvili equation for the long water waves and small-amplitude surface waves with the weak nonlinearity, weak dispersion and weak perturbation in a fluid. Breather-wave, lump-wave and lump wave–soliton solutions are derived under certain conditions via the Hirota method. With h 1 h 2 − 1 0 , where h 1 and h 2 represent the coefficients of dispersion and nonlinearity, respectively, we obtain the dark breather wave and lump wave. We observe the effects of h 1 , h 2 , h 4 , h 6 and h 8 on the dark breather wave and lump wave, where h 6 is the perturbed effect, h 4 and h 8 stand for the disturbed wave velocity effects corresponding to the y and z coordinates: h 1 and h 2 influence the amplitude of the dark breather wave; h 1 , h 4 and h 8 influence the distance between the adjacent valleys of the dark breather wave; h 1 , h 4 , h 6 and h 8 influence the location of the dark breather wave; h 2 , h 4 , h 6 and h 8 influence the amplitude of the dark lump wave; h 1 , h 4 and h 8 influence the width of the dark lump wave; h 4 , h 6 and h 8 influence the location of the dark lump wave. When h 1 h 2 − 1 > 0 , we present the fusion between a bright lump wave and one bright soliton as well as fission of one bright soliton. We also observe the fusion between a dark lump wave and one dark soliton as well as fission of one dark soliton with h 1 h 2 − 1 > 0 .

Padlock probe ligation-based rolling circle amplification (RCA) can distinguish single-nucleotide variants, which is promising for the detection of drug-resistance mutations in, e.g., Mycobacterium tuberculosis (Mtb). However, the clinical application of conventional linear RCA is restricted by its unsatisfactory picomolar-level limit of detection (LOD). Herein, we demonstrate the mechanism of a nicking-enhanced RCA (NickRCA) strategy that allows several polymerases to act simultaneously on the same looped template, generating single-stranded amplicon monomers. Limiting factors of NickRCA are investigated and controlled for higher amplification efficiency. Thereafter, we describe a NickRCA-based magnetic nanoparticle (MNP) dimer formation strategy combined with a real-time optomagnetic sensor monitoring MNP dimers. The proposed methodology is applied for the detection of a common Mtb rifampicin-resistance mutation, rpoB 531 (TCG/TTG). Without additional operation steps, an LOD of 15 fM target DNA is achieved with a total assay time of ca. 100 min. Moreover, the proposed biosensor holds the advantages of single-nucleotide mutation discrimination and the robustness to quantify targets in 10% serum samples. NickRCA produces short single-stranded monomers instead of the DNA coils produced in conventional RCA, which makes it more convenient for downstream operation, immobilization or detection, thus being applicable with different molecular tools and biosensors.

For describing the propagation of ultrashort pulses in a high-speed, long-distance optical fiber transmission system with the fourth-order dispersion, cubic–quintic nonlinearity, self-steepening and self-frequency shift, a higher-order generalized nonlinear Schrodinger equation is investigated. We get the rogue-wave solutions. Effects of the modulation instability on the optical rogue waves are studied: Increasing the growth rate of the modulation instability makes the existence time of the optical rogue wave shorter. We numerically derive the optical breathers in the chaotic wave fields via the modulation instability. Spectrum of the optical chaotic wave field can be used to indicate the appearance of the optical breather in the chaotic wave field. Optical rogue waves in the chaotic wave fields are also gotten via the modulation instability.

In this paper, we investigate the surface elevation of water waves $$\eta $$ via an NLS equation under the coefficient constraint $$\omega ^{2}=gk$$ , where g is the gravity acceleration, k and $$\omega $$ are the carrier wave number and cyclic frequency, respectively. Through the Euler formula, we derive the breather-like solitons and rogue waves on the periodic background for $$\eta $$ . Breather-like solitons and rogue waves for $$\eta $$ are related with g and k. Effects of k on the breather-like solitons for $$\eta $$ are discussed analytically and graphically: Increase of k makes the decrease in the amplitudes of the breather-like solitons for $$\eta $$ . Amplitudes of the rogue waves for $$\eta $$ increase with k increasing in the position $$X=0$$ , where X denotes the spatial coordinate. Rogue waves on the periodic background for $$\eta $$ are more stable than breather-like solitons for $$\eta $$ . Multiple rogue waves of $$\eta $$ are generated from the initial rogue waves and periodic waves for $$\eta $$ with the noise perturbations in the baseband MI regime. Quasi-periodic state for $$\eta $$ is seen with $$0.5230.544$$ .

We study the problem of dynamically controlling the shape of a cable that is fixed at one end and attached to an actuated robot at another end. This problem is relevant to unmanned aerial vehicles (UAVs) tethered to a base. While rotorcrafts, such as quadcopters, are agile and versatile in their applications and have been widely used in scientific, industrial, and military applications, one of the biggest challenges with such UAVs is their limited battery life that make the flight time for a typical UAVs limited to twenty to thirty minutes for most practical purposes. A solution to this problem lies in the use of cables that tether the UAV to a power outlet for constant power supply. However, the cable needs to be controlled effectively in order to avoid obstacles or other UAVs. In this paper, we develop methods for controlling the shape of a cable using actuation at one end. We propose a discrete model for the spatial cable and derive the equations governing the cable dynamics for both force controlled system and position controlled system. We design a controller to control the shape of the cable to attain the desired shape and perform simulations under different conditions. Finally, we propose a quasi-static model for the spatial cable and discuss the stability of this system and the proposed controller.

In this work, a two-dimensional self-assembled magnetic nanoparticle–graphene oxide (MNP-GO) nanocomposite is reported for the detection of DNA. Single-stranded DNA (ssDNA) coils, generated through a rolling circle amplification (RCA) reaction triggered by the hybridization of target oligos and padlock probes, have a strong interaction with MNP-GO nanotags through several mechanisms including π–π stacking, hydrogen bonding, van der Waals, electrostatic, and hydrophobic interactions. This interaction leads to a hydrodynamic size increase or aggregation of MNP-GO nanotags, which can be detected by a simple optomagnetic setup. Due to the high shape anisotropy, MNP-GO nanotags provide stronger optomagnetic signal than individual MNPs. Moreover, the avoidance of DNA probes (i.e., short ssDNA sequences as the biosensing receptor) provides easier material preparation and lower measurement cost. From real-time measurements of interactions between MNP-GO and RCA products amplified from a highly conserved Escherich...

In this paper, we investigate the vector multi-rogue waves for the three-coupled fourth-order nonlinear Schrodinger equations, which describe the dynamics of an alpha helical protein with the nearest and next-nearest neighbor interactions and interspine coupling. Via the Darboux-dressing transformation, the vector multi-rogue-wave solutions are derived. Based on such solutions, we present the single vector rogue wave, vector rogue wave pair and triple vector rogue wave graphically. We show that a four-petaled rogue wave with two humps and two valleys appears in two components, while the other component has an eye-shaped rogue wave. Existing time of the rogue wave decreases with the strength of higher-order linear and nonlinear effects in the alpha helical protein. We also obtain the separated and interacting vector rogue wave pairs, as well as the triple vector rogue waves. Moreover, we verify the baseband modulation instability through the linear stability analysis.

The B-type Kadomtsev-Petviashvili (BKP) equations can describe certain nonlinear phenomena in the fluids. In this paper, a BKP equation is investigated. Lump-wave, mixed lump-kink wave, breather-wa...

We investigate the breathers and their interactions via the N th binary Darboux transformation for the coupled nonlinear Schrodinger equations with negatively coherent coupling in a weakly birefringent fiber, where N is a positive integer. For the two interacting optical modes, we obtain four types of the vector breathers with different structures, i.e., the single- and double-hump Kuznetsov–Ma breathers, double-hump Akhmediev breathers, kink-type breathers, as well as their interactions. Interaction with the varying background amplitude, i.e., interaction between the single-hump/double-hump Kuznetsov–Ma breather and kink-type breather, is pointed out. Interaction between the double-hump Kuznetsov–Ma breather and double-hump Akhmediev breather is elastic with the invariant background amplitude, while interaction between the single-hump Kuznetsov–Ma breather and double-hump Akhmediev breather is inelastic. Breathers and rogue waves can coexist and interact with each other. During the interaction between an eye-shaped rogue wave and a breather, eye-shaped rogue wave can split to a pair of the beak-type rogue waves. Those waves correspond to the slowly varying envelopes of two interacting optical modes in a weakly birefringent fiber.

Optical fiber communication system is one of the core supporting systems of the modern internet age. In this paper, under investigation is a higher-order nonlinear Schrodinger system for the simultaneous propagation of two ultrashort optical pulses in an optical fiber. Based on the Lax pair, with respect to the two-component electric fields, infinitely-many conservation laws and one/N-fold binary Darboux transformations are derived, where N = 2 , 3 , … . Solitons are discussed: (1) Nondegenerate one dark–dark soliton, which is black or gray in each component, is obtained. ϵ has no relation with the soliton amplitude in each component, but has a linear correlation with the soliton velocities, where ϵ, σ1 and σ2 are the constant coefficients in the system; (2) Overtaking and head-on interactions between the two dark–dark solitons as well as the bound state are depicted. With the decreasing value of σ1, the gray solitons’ amplitudes increase, but the black solitons’ amplitudes decrease. With the decreasing value of σ2, the gray solitons’ amplitudes increase, but the black solitons’ amplitudes do not change; (3) Interaction among the three overtaking solitons and interaction between a bound state and one soliton are displayed. We find that the interactions between the two solitons and among the three solitons are elastic.

Under investigation in this paper is a coupled nonlinear Schrodinger system with the four-wave mixing term, which describes the propagation of optical waves in a birefringent fiber. Via the Darboux dressing transformation, the semirational solutions which give rise to the vector rogue waves and breathers are obtained. We display the vector rogue waves and the interaction between the rogue waves and bright–dark solitons. During the interaction, breather-like structures arise because of the interference between the dark and bright components of the soliton. Besides, it can be observed that the rogue wave and soliton merge together. Interactions between the breathers and bright–dark solitons are shown graphically. Keeping | α 1 | 2 a + | α 2 | 2 c + b α 1 α 2 ∗ + b ∗ α 1 ∗ α 2 invariant, we find that the smaller value of a c − | b | 2 yields the more obvious breather-like structure, with a and c representing the self- and cross-phase modulations, respectively, b representing the four-wave mixing effect, α 1 and α 2 being two constants. Similarly, keeping a c − | b | 2 invariant, we find that the smaller value of | α 1 | 2 a + | α 2 | 2 c + b α 1 α 2 ∗ + b ∗ α 1 ∗ α 2 yields the more obvious breather-like structure. Bound state forming between the Kuznetsov-Ma soliton and breather-like structure is illustrated.

In this paper, we investigate the ( 3 + 1 ) -dimensional Kadomtsev–Petviashvili equation in a plasma or fluid. For the amplitude of the electrostatic wave potential in the plasma or shallow-water wave in the fluid, via the Kadomtsev–Petviashvili hierarchy reduction, we obtain the semi-rational solutions in determinant form for such an equation. Interactions between the first-order lump (or rogue wave) and soliton are illustrated. We find that the lump arises and then separates from the soliton on the x – y and x – z planes; and that the rogue wave possesses a line profile and arises from the soliton (or constant background) on the y – z plane, where x , y and z are the scaled spatial coordinates. Interactions between the two lumps (or rogue waves) and two solitons are presented. Interactions between the second-order lump (or rogue wave) and one soliton are also presented.

Wetland landscape patterns are the result of various ecological and hydrological processes. Based on the land use landscape types from 1980 to 2017, a transfer matrix, landscape pattern analysis index, and principal component analysis were used to analyze the landscape pattern evolution in the Xiong’an New Area of China, which has a large area with a lake and river wetlands. The results showed that the wetland area has changed greatly since 2000 and the beach land has decreased greatly, while the area of the lake and river wetlands has increased slightly. Beach land was the dominant landscape type of the wetland. The dominant degree of the wetland landscape showed a slightly decreasing trend, and the patches tended to be scattered. The shape complexity of the ponds was the lowest, while that of rivers was the highest. The fragmentation degree of the wetland patches increased, the proportion of landscape types tended to be equalized, and the landscape heterogeneity increased. The leading factors of the wetland landscape change can be summarized as socioeconomic, meteorological, and hydrological processes, with a cumulative contribution rate of 85.3%, among which socioeconomic development was the most important factor. The results have important guiding significance for the ecological restoration and management of wetlands in the Xiong’an New Area and other wetland ecosystems with rivers and lakes.

Enhancement interaction between polybutadiene (PB) nanoparticle and polypropylene (PP) matrix by grafts via hydrogen bonding was verified and characterized by dynamic rheological analysis. The introduction of acrylamide (AM) facilitated PB uniform distribution in PP and strengthened interfacial interaction. The correlated structure based on H-bonding interaction leading to the viscoelastic nonlinearity, which restricted polymer relaxation and exhibited different rheological responses. The formation of correlated structure is an energetically favorable process driven by enthalpy, while the dynamics of construction is controlled by diffusion of the binding groups correspondingly, thus, the reconstruction and recoverability depend on the thermodynamic equilibrium distorted by either the shearing or the temperature. Therefore, the recovery ratio increases from 77.31%, 96.53%, to 98.87%, for the blend with identical composition, when increment of temperature from 180, 200–220 °C, is attributed to relaxation enhancement for both the decrement of local viscosity and the acceleration of diffusion.

Investigation and evaluation of dyes play a vital role in the process of introduction novel labels and their corresponding sensing methods, which signify opportunities for the development of biosensors. This chapter introduces applications of various dyes as labels in biosensing. Bio-recognition molecules with dyes transduce biological information into measurable optical, electrochemical, magnetic or other kinds of signals for quantification. The dyes used in this field were summarized and reviewed according to their signal types, namely colorimetric, fluorescent and electrochemical. Some dyes can transduce signals between multiple physical signals. For some most important dyes, detailed descriptions were given focused on their unique properties, labeling methods and sensing mechanisms.

The potential of metal–organic frameworks (MOFs) for applications in optoelectronics results from a unique combination of interesting photophysical properties and straightforward tunability of organic and inorganic units. Here, it is demonstrated that using MOF approach chromophores can be assembled into well‐ordered 1D arrays using metal‐oxo strands as lead structure, and the resulting porphyrinic rows exhibit unique photophysical properties and allow the realization of highly sensitive photodetectors. A porphyrinic MOF thin film, In‐TCPP surface‐coordinated MOF thin films with [021] orientation is fabricated using a layer‐by‐layer method, from In(NO3)3 and TCPP (5,10,15,20‐(4‐carboxyphenyl)porphyrin). Detailed experimental and theoretical analysis reveals that the assembly yields a structure where In‐oxo strands running parallel to the substrate fix the chromophoric linkers to yield 1D arrays of porphyrins. The frontier orbitals of this highly anisotropic arrangement are localized in these columnar arrangements of porphyrins and result in high photoactivity, which is exploited to fabricate a photodetector with record (as compared to other organic materials) responsivity in visible regime of 7.28 × 1014 Jones and short rise/fall times (0.07/0.04 s). This oriented MOF thin film‐based high‐sensitive photodetector provides a new avenue to use inorganic, stable lead structures to assemble organic semiconductors into regular arrays, thus creating a huge potential for the fabrication of optoelectronic devices., Highly photoactive, porphyrinic metal–organic framework (MOF) thin films are grown on substrates using layer‐by‐layer process. The unusual architecture of this particular MOF consists of In‐oxo chains acting as lead structure to obtain highly ordered 1D arrays of porphyrins. The MOF thin film is successfully integrated in a visible light photodetector with record sensitivity, 7.28 × 1014 Jones.

Fluid mechanics studies are applied in the turbines, airplanes, ships, rivers, windmills, pipes, etc. Under investigation is a generalized (2+1)-dimensional Hirota–Satsuma–Ito equation in fluid mechanics. Via the Hirota bilinear method, bilinear Backlund transformation is obtained, based on which the kink solutions are constructed. Breather-wave solutions are constructed via the extended homoclinic test approach. When the periods of the breather-wave solutions tend to infinity, the lump solutions are derived. It is found that the amplitudes and shapes of the breather waves keep unchanged during the propagation. Effects of the coefficients in the equation on the amplitudes and velocities for the breather waves are analyzed graphically.

The composition and distribution of wetland vegetation is critical for ecosystem diversity and sustainable development. However, tidal flat wetland environments are complex, and obtaining effective satellite imagery is challenging due to the high cloud coverage. Moreover, it is difficult to acquire phenological feature data and extract species-level wetland vegetation information by using only spectral data or individual images. To solve these limitations, statistical features, temporal features, and phenological features of multiple Landsat 8 time-series images obtained via the Google Earth Engine (GEE) platform were compared to extract species-level wetland vegetation information from Chongming Island, China. The results indicated that (1) a harmonic model obtained the phenological characteristics of wetland vegetation better than the raw vegetation index (VI) and the Savitzky–Golay (SG) smoothing method; (2) classification based on the combination of the three features provided the highest overall accuracy (85.54%), and the phenological features (represented by the amplitude and phase of the harmonic model) had the greatest impact on the classification; and (3) the classification result from the senescence period was more accurate than that from the green period, but the annual mapping result on all seasons was the most accurate. The method described in this study can be applied to overcome the impacts of the complex environment in tidal flat wetlands and to effectively classify wetland vegetation species using GEE. This study could be used as a reference for the analysis of the phenological features of other areas or vegetation types.

A method based on sparse array is applied to direction-of-arrival estimation of passive radar in this paper to increase the number of resolvable sources and improve the direction-of-arrival estimation performance for coprime array. The virtual symmetric non-uniform linear array of coprime array based on passive radar signal model is introduced. Considering the impact of direct wave, extensive cancellation algorithm is used to cancel the direct wave, with the conventional MUSIC with spatial smoothing algorithm and virtual aperture filling applied on the sparse array of passive radar; the resolution of target is low in the low signal-noise-ratio. To effectively improve the estimation of the target under the low signal-noise-ratio, a noise subspace reconstruction method is proposed. The proposed direction-of-arrival estimation method can improve the direction-of-arrival estimation performance of passive radar. The simulations are provided to demonstrate the effectiveness of the proposed method.

The effect of ultrasound on the conformational and physicochemical properties of soy protein isolate hydrolysates (SPHs) was investigated. SPHs were prepared at hydrolysis times of 20 min, 60 min, and 180 min, then treated with ultrasound for 10 min, 20 min, and 30 min at a frequency of 20 kHz and output powers of 150 W and 450 W. The structural properties and antioxidant capacities of the aqueous layer of SPHs (ASPHs) after sonication were evaluated by Fourier-transform infrared spectroscopy (FTIR), intrinsic fluorescence, DPPH radical scavenging activity assays, and microscopy observations. Results obtained showed that ultrasound treatment significantly disrupted the peptide aggregates formed during protein hydrolysis. The protein solubility was significantly increased after sonication (by up to 18.33%), as did the percentage of proteins with MW 1 kDa in ASPHs. The antioxidant capacity of ASPHs also increased, as measured by DPPH assay. FTIR analysis of ASPHs indicated that the protein secondary structures were different, with an increase in β-sheet and a decrease in α-helix and β-turn. Furthermore, the changes in fluorescence spectra of ASPHs showed the transition of protein tertiary structure with a greater exposure of Trp residues in the side chains. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations of the morphological structure of ASPHs further confirmed the significant effect of sonication on disrupting peptide aggregates. In conclusion, ultrasound can be used as an efficient treatment to promote the solubility of protein hydrolysates.

Applications of conventional linear ligation-rolling circle amplification (RCA) are restricted by the sophisticated operation steps and unsatisfactory picomolar-level detection limits. We herein demonstrate an RCA-based cascade amplification reaction that converts a side-reaction to secondary amplification, which improves the detection limit and simplifies the operation compared to linear ligation-RCA assays. The proposed nicking-assisted enzymatic cascade amplification (NECA) comprises an on-loop amplification reaction using circular templates to generate intermediate amplicons, and an off-loop amplification reaction using intermediate amplicons as primers for end amplicons. The whole NECA reaction is homogeneous and isothermal. Amplicons anneal to detection probes that are grafted onto magnetic nanoparticles (MNPs), such that MNP clusters form and can be detected in real-time using optomagnetic measurements. The optomagnetic sensor detects the presence and size increase of MNP clusters by optical transmission measurements in an oscillating magnetic field. A detection limit of 2 fM was achieved with a total assay time of ca. 70 min. By combining optomagnetic readouts of signal phase lag and hydrodynamic size increase of MNPs, NECA-based target quantification provided a wide dynamic detection range of ca. 4.5 orders of magnitude. Moreover, the specificity and the serum detection capability of the proposed method were investigated.

The (2 $$+$$ 1)-dimensional Davey–Stewartson equations concerning the evolution of surface water waves with finite depth are studied. We derive the periodic-wave solutions through the Kadomtsev–Petviashvili hierarchy reduction. We obtain the growing-decaying periodic wave and three kinds of breathers via those solutions. We obtain the periodic wave takes on the growing and decaying property. Taking the long-wave limit on the periodic-wave solutions, we derive the semirational solutions describing the interaction of the rogue wave, lump, breather and periodic wave. We illustrate the lump and rogue wave and find that the rogue wave (lump) is the long-wave limit of the periodic wave (breather).

A disturbance of reactive oxygen species (ROS) homeostasis may cause the pathogenesis of many diseases. Inspired by natural photosynthesis, this work proposes a photo-driven H2-evolving liposomal nanoplatform (Lip NP) that comprises an upconversion nanoparticle (UCNP) that is conjugated with gold nanoparticles (AuNPs) via a ROS-responsive linker, which is encapsulated inside the liposomal system in which the lipid bilayer embeds chlorophyll a (Chla). The UCNP functions as a transducer, converting NIR light into upconversion luminescence for simultaneous imaging and therapy in situ. Functioning as light-harvesting antennas, AuNPs are used to detect the local concentration of ROS for FRET biosensing, while the Chla activates the photosynthesis of H2 gas to scavenge local excess ROS. The results thus obtained indicate the potential of using the Lip NPs in the analysis of biological tissues, restoring their ROS homeostasis, possibly preventing the initiation and progression of diseases., Hydrogen can be used to reduce the concentration of reactive oxygen species (ROS), but its delivery to diseased tissues is challenging due to its low solubility. Here the authors develop a photosynthesis-inspired FRET nanocomplex to detect and scavenge local excess of ROS in the tissue using photocatalytic hydrogen production.