蝗虫光电诱导滑移捕集调控行为的研究(英文)

目的:为获得蝗虫捕集装置的优化参数,给蝗虫灾害机械化捕集装置研制提供技术支持。方法:针对近光激发蝗虫趋光特性,利用蝗虫光电诱导滑移捕集行为装置,测试了机械捕集物理环境中蝗虫滑移捕集行为特征,分析了捕集光照环境及其物理特征引起的蝗虫生物摩擦行为对滑移捕集的影响,探讨了蝗虫趋光滑移捕集的增益因素及机理。结果:LED光源恒定光照突变特性,对蝗虫趋光视觉行为的调控,易化了趋光捕集实现,而通道光照及倾斜捕集环境特征,强化了其行为响应,产生了增益捕集实现的滑移弹跳碰撞捕集行为,且当通道高度及上、下层通道倾角组合为65 mm和(30°、45°)时,捕集作用效果最佳;通道内微弱光照环境,对蝗虫运动视觉的抑制性突变刺激,有效调控了生物摩擦控制下的响应调节,产生了或滑移或滑移弹跳碰撞捕集行为,且上层通道对蝗虫弹跳碰撞阻碍效应及下层通道滑移的导引作用,有助于蝗虫趋光捕集的快速实现;30 ms发光间隔频闪光照激发蝗虫趋光捕集效果较优,640 ms发光周期交变光照调控蝗虫行为反应效果较佳。结论:试验中,频闪交变及恒定捕集光照环境调控蝗虫生物摩擦控制下滑移行为响应的敏感性,制约了捕集效果,则需利用频闪交变耦合光照的激发特性,结合通道结构组合的最佳捕集参数,增加有效激发捕集通道内蝗虫滑移弹跳行为的调控性措施,来提高蝗虫的趋光捕集效果。     

Asymmetric Binary Plasmon Resonator Arrays for Perfect Trapping of Light

We propose to achieve perfect trapping of light with asymmetric binary plasmon resonator arrays on metal substrates, in which antisymmetrically coupled resonance modes are excited in each subwavelength period to eliminate any leaky radiation. The specific structure in the study is an ultrathin binary metal stripe array on a flat metal substrate interspaced with a dielectric layer. The antiphase resonance modes are excited underneath the binary metal stripes in each period, resulting in perfect trapping of light under appropriate difference of the metal stripe widths. The trapped light is fully absorbed by metals, accompanied with an improved enhancement of the local field compared to those in symmetric structures with equal metal stripe widths. The work suggests a new way in designing optical metamaterials to manipulate light for enhanced light-matter interactions.     

Nanoplasmonic Light Trapping Metascreen Encompassing Spectrally Dense Region of Solar Spectrum

Plasmonics - An energy efficient nanoplasmonic metascreen is tailored to support near perfect absorption of sunlight around visible frequency range. To efficiently tap sunlight source, the...     

Silver Nanoparticles in Epoxy Resin Deposited on Silicon Substrates for Light Trapping

Metallic silver nanoparticles were prepared in epoxy resin using N,N-dimethylformamide (DMF) as reducing agent of silver ions at room temperature. They were characterized by UV–Vis spectroscopy, atomic force microscopy (AFM), transmission electronic microscopy (TEM), and high-resolution transmission electronic microscopy (HRTEM). The silver nanoparticles showed broadband absorption spectra attributed to high-order plasmonic resonances. The morphology of the metallic particles corresponds to elongated particles and their aggregates with a size above 30 nm. These silver nanoparticles were deposited by the spin-coating process on crystalline silicon at room temperature. Then, the antireflective properties of these samples were measured. According to the observed results, it is inferred that the films of coalesced silver nanoparticles decrease the reflectance of crystalline silicon better than particles separated by large distances. These results are discussed in terms of forward scattering of large metallic nanoparticles where higher order multipolar modes are dominant and the retardation effects are very important.     

Light Trapping Effect in Wing Scales of Butterfly Papilio peranthus and Its Simulations

Broadband light trapping effect and arrays of sub-wavelength textured structures based on the butterfly wing scales are applicable to solar cells and stealth technologies. In this paper, the fine optical structures in wing scales of butterfly Papilio peranthus, exhibiting efficient light trapping effect, were carefully examined. First, the reflectivity was measured by reflectance spectrum. Field Emission Scanning Electronic Microscope (FESEM) and Transmission Electron Microscope (TEM) were used to observe the coupling morphologies and structures of the scales. Then, the optimized 3D model of the coupling structure was created combining Scanning Electron Microscope (SEM) and TEM data. Afterwards, the mechanism of the light trapping effect of these structures was analyzed by simulation and theoretical calculations. A multilayer nano-structure of chitin and air was found. These structures are effective in increasing optical path, resulting in that most of the incident light can be trapped and adsorbed within the structure at last. Furthermore, the simulated optical results are consistent with the experimental and calculated ones. This result reliably confirms that these structures induce an efficient light trapping effect. This work can be used as a reference for in-depth study on the fabrication of highly efficient bionic optical devices, such as solar cells, photo detectors, high-contrast, antiglare, and so forth.     

Improving Solar Cells’ Light Trapping by the Low Loss Interface Photonic Crystals

Improving the silicon layer’s optical absorption is a key research point for crystalline silicon based thin film solar cells. Light trapping is a method widely adopted to achieve this research purpose. In this paper, we propose low loss interface photonic crystals layer (IPC), which is sandwiched between the crystalline silicon layer and the cover layer. The low loss interface photonic crystals layer could boost the light trapping efficiency significantly. The mechanism is that the smaller refraction index difference between silicon layer and the low loss interface photonic crystals layer could reduce the light’s interface reflection. Taking advantage of the coupling calculation by optical and electrical simulations, solar cell’s absorption efficiency and electrical performance parameters are obtained. Compared with optimized reference group, the maximum output power of the proposed solar cell could be improved by 6.44%. The result indicates that the proposed low loss interface photonic crystals layer is applicable for light’s trapping in crystalline silicon thin film solar cells.

     

Design of Plasmonic Nanoparticles for Efficient Subwavelength Light Trapping in Thin-Film Solar Cells

This paper explores geometry-sensitive scattering from plasmonic nanoparticles deposited on top of a thin-film amorphous silicon solar cell to enhance light trapping in the photo-active layer. Considering the nanoparticles as ideal spheroids, the broadband optical absorption by the silicon layer is analyzed and optimized with respect to the nanoparticle aspect ratio in both the cases of resonant (silver) and nonresonant (aluminum) plasmonic nanostructures. It is demonstrated how the coupling of sunlight with the semiconductor can be improved through tuning the nanoparticle shape in both the dipolar and multi-polar scattering regimes, as well as discussed how the native oxide shell formed on the nanospheroid surface after the prolonged action of air and moisture affects the light trapping in the active layer and changes the photocurrent generation by the solar cell.     

Plasmon-Enhanced Light Trapping to Improve Efficiency of TiO2 Nanorod-Based Dye-Sensitized Solar Cell

Localized surface plasmon resonance incurred by silver nanoparticles is used to enhance the photoelectric conversion efficiency of a TiO₂ nanorod-based dye-sensitized solar cell (DSSC). Improved light transmission is observed experimentally in silver nanoparticle-coated FTO glass. The transmission data are used to explore the effect on electrical parameters of DSSC using theoretical model. Current density increased from 11.7 to 12.34 mA/cm² and open-circuit voltage increased from 704 to 709.5 mV. Overall efficiency enhancement of 6.67 % is observed in TiO₂ nanorod-based DSSC due to plasmon-induced light trapping.     

Diffraction‐Grated Perovskite Induced Highly Efficient Solar Cells through Nanophotonic Light Trapping

Achieving light harvesting is crucial for the efficiency of the solar cell. Constructing optical structures often can benefit from micro‐nanophotonic imprinting. Here, a simple and facile strategy is developed to introduce a large area grating structure into the perovskite‐active layer of a solar cell by utilizing commercial optical discs (CD‐R and DVD‐R) and achieve high photovoltaic performance. The constructed diffraction grating on the perovskite active layer realizes nanophotonic light trapping by diffraction and effectively suppresses carrier recombination. Compared to the pristine perovskite solar cells (PSCs), the diffraction‐grating perovskite devices with DVD obtain higher power conversion efficiency and photocurrent density, which are improved from 16.71% and 21.67 mA cm^?2 to 19.71% and 23.11 mA cm^?2. Moreover, the stability of the PSCs with diffraction‐grating‐structured perovskite active layer is greatly enhanced. The method can boost photonics merge into the remarkable perovskite materials for various applications.     

A Surface Design for Enhancement of Light Trapping Efficiencies in Thin Film Silicon Solar Cells

We report on a surface design of thin film silicon solar cells based on silver nanoparticle arrays and blazed grating arrays. The light transmittance is increased at the front surface of the cells, utilizing the surface plasmon resonance effect induced by silver nanoparticle arrays. As a reflection layer structure, blazed gratings are placed at the rear surface to increase the light reflectance at bottom of the thin film cells. With the combination of the silver nanoparticle arrays and the blazed gratings, the light trapping efficiency of the thin film solar cell is characterized by its light absorptance, which is determined from the transmittance at front surface and the reflectance at bottom, via the finite-difference time-domain (FDTD) numerical simulation method. The results reveal that the light trapping efficiency is enhanced as the structural parameters are optimized. This work also shows that the surface plasmon resonance effect induced by the silver nanoparticles and the grating characteristics of the blazed gratings play crucial roles in the design of the thin film silicon solar cells.     

Optimization of Dielectric-Coated Silver Nanoparticle Films for Plasmonic-Enhanced Light Trapping in Thin Film Silicon Solar Cells

Surface plasmonic-enhanced light trapping from metal nanoparticles is a promising way of increasing the light absorption in the active silicon layer and, therefore, the photocurrent of the silicon solar cells. In this paper, we applied silver nanoparticles on the rear side of polycrystalline silicon thin film solar cell and systematically studied the dielectric environment effect on the absorption and short-circuit current density (Jsc) of the device. Three different dielectric layers, magnesium fluoride (MgF₂, n?=?1.4), tantalum pentoxide (Ta₂O₅, n?=?2.2), and titanium dioxide (TiO₂, n?=?2.6), were investigated. Experimentally, we found that higher refractive index dielectric coatings results in a redshift of the main plasmonic extinction peak and higher modes were excited within the spectral region that is of interest in our thin film solar cell application. The optical characterization shows that nanoparticles coated with highest refractive index dielectric TiO₂ provides highest absorption enhancement 75.6 %; however, from the external quantum efficiency characterization, highest short-circuit current density Jsc enhancement of 45.8 % was achieved by coating the nanoparticles with lower refractive index MgF₂. We also further optimize the thickness of MgF₂ and a final 50.2 % Jsc enhancement was achieved with a 210-nm MgF₂ coating and a back reflector.     

Trapping single ions inside single ion channels.

Single Ca++-activated K+ channels from rat muscle plasma membranes are inhibited by Ba++. A single Ba++ entering the channel's conduction pore induces a long-lived blocked state. This study employs Ba++ as a probe of the channel's conduction pathway to show that the channel can be forced to close with a single Ba++ ion inside the pore. A Ba++ ion inside the closed channel is trapped and cannot escape until the channel opens. The results demonstrate that in the channel's closed state, the cytoplasmic side of the conduction pore is obstructed to the passage of ions.     

Resonant Aluminum Nanodisk Array for Enhanced Tunable Broadband Light Trapping in Ultrathin Bulk Heterojunction Organic Photovoltaic Devices

A cost-effective approach to enhancing broadband light trapping in ultrathin bulk heterojunction organic photovoltaic (OPV) devices is proposed. This is achieved by simply inserting an array of Al nanodisks at the interface of the ITO anode and the organic active layer; forming circular plasmonic nanopatch cavities (between the nanodisks and the Al cathode) that sandwich the active layer. Through interactions between the surface plasmon polaritons localized at the nanodisk and the cathode, a tunable broadband resonance peak spanning 450?C700?nm in the scattering cross-section spectrum is formed, thereby enhancing the electromagnetic field in the active layer. Compared to an OPV device with a 60-nm-thick PCPDTBT/PC₆₀BM layer, our numerical simulations reveal that integrated absorption enhancements of up to 40?% can be achieved in an equivalent device integrated with an array of nanodisks with a diameter of 100?nm and a periodicity of 250?nm. From the analysis of the structure?Cperformance relationships, implications for the design of these nanopatch cavities for light harvesting in ultrathin OPV devices are discussed.     

Light Trapping with Dielectric Scatterers in Single‐ and Tandem‐Junction Organic Solar Cells

Efficient dielectric scatterers based on a mixture of TiO₂ nanoparticles and polydimethylsiloxane are demonstrated for light trapping in semitransparent organic solar cells. An improvement of 80% in the photocurrent of an optimized semitransparent solar cell is achieved with the dielectric scatterer with ≈100% diffuse reflectance for wavelengths larger than 400 nm. For a parallel tandem solar cell, the dielectric scatterer generates 20% more photocurrent compared with a silver mirror beneath the cell; for a series tandem solar cell, the dielectric scatterer can be used as a photocurrent balancer between the subcells with different photoabsorbing materials. The power conversion efficiency of the tandem cell in series configuration with balanced photocurrent in the subcells exceeds that of an optimized standard solar cell with a reflective electrode. The characteristics of polydimethylsiloxane, such as flexibility and the ability to stick conformably to surfaces, also remain in the dielectric scatterers, which makes the demonstrated light trapping configuration highly suitable for large scale module manufacturing of roll‐to‐roll printed organic single‐ or tandem‐junction solar cells.     

Tuning of Light Trapping and Surface Plasmon Resonance in Silver Nanoparticles/c-Si Structures for Solar Cells

In this work, we investigate silver (Ag) nanoparticle-related plasmonic effect on light absorption in Si substrate. Ag nanoparticles (Ag-NPs) deposited on top of Si were used to capture and couple incident light into these structures by forward scattering. We demonstrate that we can control nanoparticle size and shape while varying deposition time and annealing parameters. By the increase of the total time of the reaction process, morphology of Ag-NPs evolutes affecting the number and the width of surface plasmon resonance peaks, whereas for changed annealing parameters (temperature and time), the effect is more pronounced on the broadening and the position of peaks. Specific morphology of Ag-NPs can exhibit an interesting enhancement of optical properties which enables plasmon-related application in photovoltaic solar cells.     

Trapping the sensor

Voltage-gated ion channels open in response to a change in membrane potential. The "sensor," or the channel's molecular entity responsible for the detection of voltage change, is formed by a transmembrane element, rich with basic residues, called the "voltage sensor" or the "S4 domain." The movement of the S4 drives a global conformational change leading to the opening of the permeation pathway and ion conduction. In this issue of Neuron, Sch?nherr and colleagues show that physical constrains of the "gating canal," or the crevice through which the S4 moves, determines whether voltage-gated potassium channels open quickly or slowly.     

Escherichia coli glutamyl-tRNA reductase. Trapping the thioester intermediate

In the first step of tetrapyrrole biosynthesis in Escherichia coli, glutamyl-tRNA reductase (GluTR, encoded by hemA) catalyzes the NADPH-dependent reduction of glutamyl-tRNA to glutamate-1-semialdehyde. Soluble homodimeric E. coli GluTR was made by co-expressing the hemA gene and the chaperone genes dnaJK and grpE. During Mg(2+)-stimulated catalysis, the reactive sulfhydryl group of Cys-50 in the E. coli enzyme attacks the alpha-carbonyl group of the tRNA-bound glutamate. The resulting thioester intermediate was trapped and detected by autoradiography. In the presence of NADPH, the end product, glutamate-1-semialdehyde, is formed. In the absence of NADPH, E. coli GluTR exhibited substrate esterase activity. The in vitro synthesized unmodified glutamyl-tRNA was an acceptable substrate for E. coli GluTR. Eight 5-aminolevulinic acid auxotrophic E. coli hemA mutants were genetically selected, and the corresponding mutations were determined. Most of the recombinant purified mutant GluTR enzymes lacked detectable activity. Based on the Methanopyrus kandleri GluTR structure, the positions of the amino acid exchanges are close to the catalytic domain (G7D, E114K, R314C, S22L/S164F, G44C/S105N/A326T, G106N, S145F). Only GluTR G191D (affected in NADPH binding) revealed esterase but no reductase activity.