Blooms of cyanobacteria cause enormous losses in both the economy and environment. Cyanophages are of great potential for fighting blooming cyanobacteria. Research report on cyanophage of ...bloom-forming cyanobacterium,
Microcystis elabens
is deficient. vB_MelS-Me-ZS1 (abbreviated as Me-ZS1) was isolated from fresh water by double-layer agar plate method using
M. elabens
. TEM exhibited that cyanosiphovirus Me-ZS1 has an icosahedral head about 60 nm in diameter, and a noncontractile tail approximately 260 nm. Experimental infection against 15 cyanobacterial strains showed that Me-ZS1 can infect 12 strains across taxonomic orders (Chroococcales, Nostocales and Oscillatoriales). High-throughput sequencing and bioinformatics analysis revealed that Me-ZS1 has a double-stranded DNA genome of 49,665 bp, with a G + C content of 58.22%, and 73 predicted open reading frames (ORFs). BLASTn and ORF comparisons showed that Me-ZS1 shares very low homology with the public sequences, and the phylogenetic tree based on TerL indicated that Me-ZS1 may delegate a novel and genetically distinct clade of Siphoviridae phages. In microcosm experiment, Me-ZS1 represented apparent effect on reducing relative abundance of cyanobacteria, increasing relative abundance of Saprospiraceae and protecting brocade carp (
Carassius auratus
) in cyanobacterial bloom water. This study isolated and characterized a novel broad-host-range
Microcystis
phage Me-ZS1 presenting a genetically distinct clade of freshwater cyanophage. The features of cyanophage Me-ZS1 provide a potential solution to the loss caused by cyanobacterial bloom.
A unique lytic phage infecting
was isolated and identified.
phage Ca belongs to the family Autographiviridae, possessing an icosahedral head with a diameter of 55 nm and a short non-contractile tail. ...Unusually, the burst size of
phage Ca of 10,292 ± 1,097 plaque-forming units (PFUs)/cell is much larger than other dsDNA phages reported before. Compared to the genome of the related phage,
phage Ca genome contains extra genes including DNA mimic ocr, dGTP triphosphohydrolase inhibitor, endonuclease, endonuclease VII, and HNH homing endonuclease gene. Extraordinarily, the phage developed different sizes of plaques when a single plaque was picked out and inoculated on a double-layer Luria broth agar plate with its host. Furthermore, varied packaging tightness for the tails of
phage Ca was observed (tail length: 4.35-45.92 nm). Most of the tails appeared to be like a cone with appendages, some were dot-like, bun-like, table tennis racket handle-like, and ponytail-like. Although the complete genome of
phage Ca is 40,286 bp, an incomplete genome with a deletion of a 397-bp fragment, containing one ORF predicted as HNH homing endonuclease gene (HEG), was also found by high throughput sequencing. Most of the genome of the virus particles in large plaques is complete (>98%), while most of the genome of the virus particles in small plaques is incomplete (>98%), and the abundance of both of them in medium-sized plaques is similar (complete, 40%; incomplete, 60%). In an experiment to see if the phage could be protective to brocade carps intramuscularly injected with
LY-23 and phage Ca, the protection rate of
phage Ca to brocade carp (
Koi) against
was 33.38% (0.01 <
< 0.05). This study highlights some new insights into the peculiar biological and genomic characteristics of phage.
•In this work, we propose a complex amplitude control method of metasurface based on full phase modulation.•The complex amplitude of the co-polarized component of the incident circular-polarized ...light is controlled by the circular nanopillars, and the complex amplitude of the cross-polarized component is controlled by the rectangular nanopillars.
Unlike the Pancharatnam-Berry phase and spin-decoupled metasurface, which only modifies the phase of the cross-polarization components, the full-phase modulation metasurface achieves independent wavefront control of the co– and cross-polarization components of circularly polarized waves. As a result, a novel concept for multifunctional manipulation of the metasurface is presented in this paper, which is a complex amplitude control method based on full-phase modulation via a metasurface. This method allows for simultaneous and independent amplitude and phase manipulation of the co– and cross-polarization components of circularly polarized waves. At 980 nm wavelength, the results of complex amplitude control for incident circularly polarized light (left circularly polarized or right circularly polarized) demonstrate the feasibility of the method.
Crop growth and yield monitoring are essential for food security and agricultural economic return prediction. Remote sensing is an efficient technique for measuring growing season crop canopies and ...providing information on the spatial variability of crop yields. In this study, ten vegetation indices (VIs) derived from time series PlanetScope and Sentinel-2 images were used to investigate the potential to estimate corn grain yield with different regression methods. A field-scale spatial crop yield prediction model was developed and used to produce yield maps depicting spatial variability in the field. Results from this study clearly showed that high-resolution PlanetScope satellite data could be used to detect the corn yield variability at field level, which could explain 15% more variability than Sentinel-2A data at the same spatial resolution of 10 m. Comparison of the model performance and variable importance measure between models illustrated satisfactory results for assessing corn productivity with VIs. The green chlorophyll vegetation index (GCVI) values consistently produced the highest correlations with corn yield, accounting for 72% of the observed spatial variation in corn yield. More reliable quantitative yield estimation could be made using a multi-linear stepwise regression (MSR) method with multiple VIs. Good agreement between observed and predicted yield was achieved with the coefficient of determination value being 0.81 at 86 days after seeding. The results would help farmers and decision-makers generate predicted yield maps, identify crop yield variability, and make further crop management practices timely.
In this paper, two polarization-insensitive Gallium Nitride (GaN) metasurfaces based on a dynamic phase for adjusting the wavefront are proposed. Specifically, we obtained the target phase to satisfy ...some design conditions by changing the structural parameters at the nanoscales. Under the irradiation of linearly polarized (LP) light and circularly polarized (CP) light, respectively, one of the metasurfaces can generate a focused beam with an efficiency of 84.7%, and the other can generate a vortex beam with a maximum efficiency of 76.6%. Our designed metasurfaces will have important applications in optical communication, holographic projection, and particle capture.
The positive and negative terrains (P–N terrains) of the Loess Plateau of China are important geographical topography elements for measuring the degree of surface erosion and distinguishing the types ...of landforms. Loess shoulder-lines are an important terrain feature in the Loess Plateau and are often used as a criterion for distinguishing P–N terrains. The extraction of shoulder lines is important for predicting erosion and recognising a gully head. However, existing extraction algorithms for loess shoulder-lines in areas with insignificant slopes need to be improved. This study proposes a regional fusion (RF) method that integrates the slope variation-based method and region-growing algorithm to extract loess shoulder-lines based on a Digital Elevation Model (DEM) at a spatial resolution of 5 m. The RF method introduces different terrain factors into the growth standards of the region-growing algorithm to extract loess-shoulder lines. First, we employed a slope-variation-based method to build the initial set of loess shoulder-lines and used the difference between the smoothed and real DEMs to extract the initial set for the N terrain. Second, the region-growing algorithm with improved growth standards was used to generate a complete area of the candidate region of the loess shoulder-lines and the N terrain, which were fused to generate and integrate contours to eliminate the discontinuity. Finally, loess shoulder-lines were identified by detecting the edge of the integrated contour, with results exhibiting congregate points or spurs, eliminated via a hit-or-miss transform to optimise the final results. Validation of the experimental area of loess ridges and hills in Shaanxi Province showed that the accuracy of the RF method based on the Euclidean distance offset percentage within a 10-m deviation range reached 96.9% compared to the manual digitalisation method. Based on the mean absolute error and standard absolute deviation values, compared with Zhou’s improved snake model and the bidirectional DEM relief-shading methods, the proposed RF method extracted the loess shoulder-lines highly accurately.
Water quality estimation tools based on real-time monitoring are essential for the effective management of organic pollution in watersheds. This study aims to monitor changes in the levels of ...chemical oxygen demand (COD, CODMn) and dissolved organic matter (DOM) in Erhai Lake Basin, exploring their relationships and the ability of DOM to estimate COD and CODMn. Excitation emission matrix–parallel factor analysis (EEM–PARAFAC) of DOM identified protein-like component (C1) and humic-like components (C2, C3, C4). Combined with random forest (RF), maximum fluorescence intensity (Fmax) values of components were selected as estimation parameters to establish models. Results proved that the COD of rivers was more sensitive to the reduction in C1 and C2, while CODMn was more sensitive to C4. The DOM of Erhai Lake thrived by internal sources, and the relationship between COD, CODMn, and DOM of Erhai Lake was more complicated than rivers (inflow rivers of Erhai Lake). Models for rivers achieved good estimations, and by adding dissolved oxygen and water temperature, the estimation ability of COD models for Erhai Lake was significantly improved. This study demonstrates that DOM-based machine learning can be used as an alternative tool for real-time monitoring of organic pollution and deepening the understanding of the relationship between COD, CODMn, and DOM, and provide a scientific basis for water quality management.
Lommel beam is a non-diffractive vortex beam of high concern recently, widely used in communication and turbulence studies. However, conventional methods of generating Lommel beams, such as using ...spatial light modulators (SLMs), are limited by their low resolution, poor phase manipulation, and small numerical aperture (NA). Here, non-diffractive Lommel beams based on all-dielectric metasurfaces are proposed. Using the Pancharatnam-Berry (PB) phase arrangement, the focal depth of the main lobe of the generated beam can reach 75 µm (∼119
λ
). Additionally, the broadband characteristics of the designed metasurface between 550 and 710 nm are observed. The resulting beam is demonstrated to show excellent self-healing properties by placing up obstacles. We also combine the phase of the Dammann grating with that of the Lommel beam to create a metasurface capable of producing a 1 × 4 Lommel beam array; the generated beams are still characterized by uniformity and non-diffraction. This study provides a new idea for Lommel beam generation with promising applications in optical communication, optical tweezers, and laser fabrication.
Photonic Spin Hall Effect (PSHE) is a relativistic spin-orbit coupling phenomenon that can provide a wide range of spin-controlled nano-photon applications. However, most of the research results have ...been achieved only on 1D modulation of PSHE and the PSHE is very weak because of the extremely small spin-orbit interaction. Here, we propose a novel method to achieve a 2D manipulation of PSHE based on the broadband dielectric metasurface with refractive efficiency of above 80%. Using silicon nitride nanorods with perfect half-wave plates properties, a high-efficiency metasurface is designed, which demonstrated that directly realizes the high-performance PSHE in the ultraviolet region. Moreover, the metasurface can realize longitudinal focusing and transverse deflection of photons in different spin states by using the Pancharatnam-Berry (PB) phase and propagation phase, thus enabling 2D flexible manipulation of spin photons. The results show that the broadband dielectric metasurface offers a method to develop a high-efficiency PSHE for generating and manipulating spin-polarized photons, achieving important applications in optical communication, beam shaping, and optical sensors.
This study proposes two types of metasurfaces to adjust the phase of wavefront based on geometric phases. Specifically, a meta-atom etched by two different elliptic cylinders possesses more adjusted ...parameters and satisfies some demanding design conditions. Under the illumination of circularly polarized light, one of them, metalens, can focus the light with a focusing efficiency of 60 %. The other can generate vortex beams with an efficiency of ∼55%. Such metasurfaces can be used as planar optical components in biological, medical, and intelligent wearable fields.
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