DataSheet1_Quantifying the Temporal and Spatial Patterns of Ecosystem Services and Exploring the Spatial Differentiation of Driving Factors: a Case Study of Sichuan Basin, China.docx

Exploring the factors that drive the change of ecosystem services (ES) is very important for maintaining ES function and zoning ecological management, especially in the Sichuan Basin area with high spatial heterogeneity such as natural and socio-economic characteristics. Taking the Sichuan Basin in China as an example, the PCA-MGWR model was constructed to explore the temporal and spatial patterns of ES in the Sichuan Basin from 2000 to 2015. The potential driving factors including anthropogenic factors, geomorphological factors, climate factors, and vegetation factors would be analyzed by principal component analysis (PCA). To illustrate the impact of spatial dependence in the data, the multi-scale geographically weighted regression (MGWR) technology was selected to explore the spatial differentiation of the impact of these four dimensions on ES to reflect the local differences of ecosystem service driving mechanisms in more detail. The results showed that 1) from the perspective of time series evolution, carbon storage (CS) and soil conservation (SC) in ES in the Sichuan Basin showed an upward trend, while water yield (WY) showed a downward trend; from the perspective of spatial patterns, except the main urban areas of Chengdu and Chongqing, the CS service level of other regions was high; The spatial distribution characteristics of SC services were “low in the middle and high in the periphery”; the high value area of WY service was located in Northeast Sichuan. 2) Among natural factors, elevation (DEM), slope (SLO), NDVI, annual average temperature (TEM), and annual average precipitation (PRE) had a higher contribution rate to ES, while among socio-economic factors, GDP density (GDP), night light (LIG), and population density (POP) had a higher contribution rate to ES, while other factors had a lower contribution rate. 3) Combined with the PCA-MGWR model, we analyzed the comprehensive response and spatial differentiation of driving factors to ES in the Sichuan Basin and explained in detail the influence of anthropogenic factors, geomorphological factors, climatic factors, and vegetation factors and their spatial heterogeneity in ES. It is expected that the spatial differences in the impact degree of different indicators can be considered when formulating the countermeasures of ES in the Sichuan Basin, to provide theoretical support for the implementation of regional ecological management and control.</p

Reversible Unfolding and Folding of the Metalloprotein Ferredoxin Revealed by Single-Molecule Atomic Force Microscopy

Plant type [2Fe-2S] ferredoxins function primarily as electron transfer proteins in photosynthesis. Studying the unfolding–folding of ferredoxins in vitro is challenging, because the unfolding of ferredoxin is often irreversible due to the loss or disintegration of the iron–sulfur cluster. Additionally, the in vivo folding of holo-ferredoxin requires ferredoxin biogenesis proteins. Here, we employed atomic force microscopy-based single-molecule force microscopy and protein engineering techniques to directly study the mechanical unfolding and refolding of a plant type [2Fe-2S] ferredoxin from cyanobacteria Anabaena. Our results indicate that upon stretching, ferredoxin unfolds in a three-state mechanism. The first step is the unfolding of the protein sequence that is outside and not sequestered by the [2Fe-2S] center, and the second one relates to the force-induced rupture of the [2Fe-2S] metal center and subsequent unraveling of the protein structure shielded by the [2Fe-2S] center. During repeated stretching and relaxation of a single polyprotein, we observed that the completely unfolded ferredoxin can refold to its native holo-form with a fully reconstituted [2Fe-2S] center. These results demonstrate that the unfolding–refolding of individual ferredoxin is reversible at the single-molecule level, enabling new avenues of studying both folding–unfolding mechanisms, as well as the reactivity of the metal center of metalloproteins in vitro

Angular Trapping of Spherical Janus Particles

Developing angular trapping methods, which will enable optical tweezers to rotate a micronized bead, is of great importance for the studies of biomacromolecules during a wide range of torque-generation processes. Here we report a novel controlled angular trapping method based on composite Janus particles. We used a chemically synthesized Janus particle, which consists of two hemispheres made of polystyrene (PS) and poly(methyl methacrylate) (PMMA) respectively, as a model system to demonstrate this method. Through computational and experimental studies, we demonstrated the feasibility to control the rotation of a Janus particle in a linearly polarized laser trap. Our results showed that the Janus particle aligned its two hemisphere's interface parallel to the laser propagation direction as well as the laser polarization direction. In our experiments, the rotational state of the particle can be easily and directly visualized by using a CMOS camera, and does not require complex optical detection system. The rotation of the Janus particle in the laser trap can be fully controlled in real time by controlling the laser polarization direction. Our newly developed angular trapping technique has the great advantage of easy implementation and real time controllability. Considering the easy chemical synthesis of Janus particles and implementation of the angular trapping, this novel method has the potential of becoming a general angular trapping method. We anticipate that this new method will significantly broaden the availability of angular trapping in the biophysics community, and expand the scope of the research that can be enabled by the angular trapping approach

Visualization 1 twisting of microsphere probe.mp4

This video demonstrates the impact of the microsphere on the resonant frequency of the AFM cantilever,and the twisting of the microsphere probe when operating in tapping mode

Supplementary document for Microsphere probe: Combining microsphere-assisted imaging microscopy with AFM - 6519947.pdf

ANSYS simulation,comparison of standard probe and microsphere probe, Physical imag

Visualization 3.mp4

Scanning of image stitching to extend the field of microsphere imaging

Visualization 1.mp4

Magnified imaging larger than the size of the microsphere

Supplementary document for Addressing the imaging extension of microsphere-assisted nanoscope - 6079101.pdf

Supplemental Documen

Visualization 2.mp4

The real-time magnified imaging phenomenon of microspheres

Excitons Enabled Topological Phase Singularity in a Single Atomic Layer

The nontrivial and rigorous Heaviside phase jump behavior of phase singularities (PSs) empowers exotic topological modes and widely divergent nature compared to neighboring points, which has attracted great attention in condensed matter physics as well as applications in photonics and ultrasensitive sensors. Here we demonstrate the universal existence of a family of topologically protected PSs generated from exciton resonances of single-atom layers. We obtain the PSs by coating the transition metal dichalcogenide (TMDC) monolayers on a nonabsorptive semi-infinite substrate without surface plasmon effect or other assisted resonators, which exploits the benefits of both exciton-dominated enhancement and peculiarities of the singular phase. We show that a refractive indices matched transparent substrate enables TMDC monolayers to exhibit topologically protected zero reflection accompanied by a perfect Heaviside π-phase jump at strong light adsorptions, which can be utilized to radically reduce the thickness of PS-based devices to a single atomic layer. By using the TMDC monolayer-based PSs for refractive index biosensors, we demonstrate its superior phase sensitivity at a level of 104 degrees per refractive index unit and detection of bioactive bacteria, respectively, which is comparable to the cutting-edge surface plasmon and Fabry–Perot resonance sensors. Our proof-of-concept results offer experimental and theoretical insights into a single atomic playground for flat singular optics and label-free biosensing technologies