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We report the rational engineering of a remarkably stable yellow fluorescent protein (YFP), ‘hyperfolder YFP’ (hfYFP), that withstands chaotropic conditions that denature most biological structures within seconds, including superfolder green fluorescent protein (GFP). hfYFP contains no cysteines, is chloride insensitive and tolerates aldehyde and osmium tetroxide fixation better than common fluorescent proteins, enabling its use in expansion and electron microscopies. We solved crystal structures of hfYFP (to 1.7-Å resolution), a monomeric variant, monomeric hyperfolder YFP (1.6 Å) and an mGreenLantern mutant (1.2 Å), and then rationally engineered highly stable 405-nm-excitable GFPs, large Stokes shift (LSS) monomeric GFP (LSSmGFP) and LSSA12 from these structures. Lastly, we directly exploited the chemical stability of hfYFP and LSSmGFP by devising a fluorescence-assisted protein purification strategy enabling all steps of denaturing affinity chromatography to be visualized using ultraviolet or blue light. hfYFP and LSSmGFP represent a new generation of robustly stable fluorescent proteins developed for advanced biotechnological applications.

An insulator–metal transition (IMT) is an emergent characteristic of quantum materials, which have a great amount promise for applications, such as memories, optical switches, and analog brain functions. This is due to their ability to switch between two well-defined states. Thus, the characterization of the state-switching process is essential for the application of these materials. For vanadium dioxide ([Formula: see text]), the phase transition can be determined from temperature, magnetic field, and dielectric constant. In this paper, we propose a diamond quantum sensing approach based on nitrogen-vacancy centers for analyzing phase transitions. By using lock-in-based optically detected magnetic resonance and Rabi measurement protocols, temperature and magnetic field can reflect local IMT information of the circuit, and microwave can determine IMT information of an electrical isolation region. Our multifunctional quantum sensor exhibits local, nondestructive, and integrated measurements, which are useful for reliability testing in IMT technology applications.

Focusing electromagnetic field to enhance the interaction with matter has been promoting researches and applications of nano electronics and photonics. Usually, the evanescent-wave coupling is adopted in various nano structures and materials to confine the electromagnetic field into a subwavelength space. Here, based on the direct coupling with confined electron oscillations in a nanowire, we demonstrate an extreme localization of microwave field down to 10$^{-6}\lambda$. A hybrid nanowire-bowtie antenna is further designed to focus the free-space microwave to this deep-subwavelength space. Detected by the nitrogen vacancy center in diamond, the field intensity and microwave-spin interaction strength are enhanced by 2.0$\times$10$^{8}$ and 1.4$\times$10$^{4}$ times, respectively. Such an extreme concentration of microwave field will further promote integrated quantum information processing, sensing and microwave photonics in a nanoscale system., Comment: 16 pages, 10 figures

The leaf area index (LAI) is a key parameter for describing the canopy structure of apple trees. This index is also employed in evaluating the amount of pesticide sprayed per unit volume of apple trees. Hence, numerous manual and automatic methods have been explored for LAI estimation. In this work, the leaf area indices for different types of apple trees are obtained in terms of multispectral remote-sensing data collected with an unmanned aerial vehicle (UAV), along with simultaneous measurements of apple orchards. The proposed approach was tested on apple trees of the “Fuji”, “Golden Delicious”, and “Ruixue” types, which were planted in the Apple Experimental Station of the Northwest Agriculture and Forestry University in Baishui County, Shaanxi Province, China. Five vegetation indices of strong correlation with the apple leaf area index were selected and used to train models of support vector regression (SVR) and gradient-boosting decision trees (GBDT) for predicting the leaf area index of apple trees. The best model was selected based on the metrics of the coefficient of determination (R2) and the root-mean-square error (RMSE). The experimental results showed that the gradient-boosting decision tree model achieved the best performance with an R2 of 0.846, an RMSE of 0.356, and a spatial efficiency (SPAEF) of 0.57. This demonstrates the feasibility of our approach for fast and accurate remote-sensing-based estimation of the leaf area index of apple trees.

Electric-field control of magnetism (EFCM) is very important for the exploration of high-density, fast, and nonvolatile random-access memory with ultralow energy consumption. Here, we report the electric-field-induced ferroelectric phase transitions in Pb(Mg1/3Nb2/3)0.82Ti0.18O3 (PMN-0.18PT) and symmetry breaking of EFCM behaviors for corresponding directions in multiferroic heterostructures composed of amorphous ferromagnetic Co40Fe40B20 (CoFeB) and PMN-0.18PT. We uncover a new mechanism behind the unusual phenomena, involving coupling between CoFeB and PMN-0.18PT via complex cooperation of electric-field-induced ferroelectric phase transitions, competition of different ferroelectric domains, and internal electric field in PMN-0.18PT. The deterministic EFCM with reversible and nonvolatile nature opens up a new avenue for exploring EFCM in multiferroic heterostructures and is also significant for applications.

We report electric-field control of magnetism of (Co/Pt)3 multilayers involving perpendicular magnetic anisotropy with different Co-layer thicknesses grown on Pb(Mg,Nb)O3-PbTiO3 (PMN-PT) FE substrates. For the first time, electric-field control of the interface magnetic anisotropy, which results in the spin reorientation transition, was demonstrated. The electric-field-induced changes of the bulk and interface magnetic anisotropies can be understood by considering the strain-induced change of magnetoelastic energy and weakening of Pt 5d-Co 3d hybridization, respectively. We also demonstrate the role of competition between the applied magnetic field and the electric field in determining the magnetization of the sample with the coexistence phase. Our results demonstrate electric-field control of magnetism by harnessing the strain-mediated coupling in multiferroic heterostructures with perpendicular magnetic anisotropy and are helpful for electric-field modulations of Dzyaloshinskii-Moriya interaction and Rashba effect at interfaces to engineer new functionalities.

Anisotropy and overconsolidation are two important features of depositional clay and are not comprehensively addressed in current cavity expansion solutions. Aiming at better modeling the cavity expansion responses in the natural soils, this paper develops a novel and rigorous elastoplastic semi-analytical solution by implementing the advanced anisotropic unified hardening (UH) model in conjunction with incorporating the anisotropic SMP criterion. The novel incorporation of the anisotropic SMP criterion and the proper consideration of overconsolidated properties are the major contributions of the present solution. By utilizing the anisotropic stress transformation method, the initial stress-induced anisotropy, anisotropic yielding and anisotropic failure of soil are also incorporated into the proposed solution. Following the derived constitutive equations in incremental form and large strain theory, both undrained and the drained cases are reduced to boundary-value problems consisting of several first-order ordinary differential equations formed in the Lagrangian scheme. Detailed parametric analyses are presented and compared with other existing solutions to investigate the effects of anisotropy and initial overconsolidation on the cavity responses. The present solution could properly capture the cross-anisotropy and 3D strength of overconsolidated soil and hence provides a more advanced and generic approach for modeling the cavity expansion responses in wide ranges of soils.

The laser performance of coumarin 440 (C440) and coumarin 460 (C460) mixture is studied. The mixture dyes demonstrated broader and more efficient tuning curves compared with those of coumarin 440 and coumarin 460. A wide tuning range from 421 nm to 482 nm is achieved. The highest conversion efficiency of 12.2% is obtained at 453 nm. Comparing with the efficiencies of individual dye C440 and C460, which are ∼5%, the tuning range and the conversion efficiency of the coumarin 440 (C440) and coumarin 460 (C460) mixture are the best under the same condition so far. All our results indicate that high laser performance can be achieved using the co-doped laser dyes of coumarin 440 and coumarin 460.

We have determined the crystal structure of Clover, one of the brightest fluorescent proteins, and found that its T203H/S65G mutations relative to wild-type GFP lock the critical E222 side chain in a fixed configuration that mimics the major conformer of that in EGFP. The resulting equilibrium shift to the predominantly deprotonated chromophore increases the extinction coefficient (EC), opposes photoactivation, and is responsible for the bathochromic shift. Clover's brightness can further be attributed to a π-π stacking interaction between H203 and the chromophore. Consistent with these observations, the Clover G65S mutant reversed the equilibrium shift, dramatically decreased the EC, and made Clover photoactivatable under conditions that activated photoactivatable GFP. Using the Clover structure, we rationally engineered a non-photoactivatable redox sensor, roClover1, and determined its structure as well as that of its parental template, roClover0.1. These high-resolution structures provide deeper insights into structure-function relationships in GFPs and may aid the development of excitation-improved ratiometric biosensors.

We report electric-field control of magnetism of (Co/Pt)

Two-dimensional layered materials with remarkable thermoelectric coefficients are promising candidates for sustainable thermopower batteries. Here, we investigate the anomalous Nernst effect and anomalous Hall effect in the polycrystalline Fe 3 GeTe 2 thin films. While its Seebeck coefficient and anomalous Hall angle (or magnetization) monotonously increase and decrease with temperature, respectively, the anomalous Nernst coefficient of the Fe 3 GeTe 2 films exhibits a peak value of 0.28 μV K–1 T–1 at 150 K, which is the compromised outcome between the enhanced Seebeck effect and the gradually weakened magnetism with elevating temperature. A noticeable anomalous Nernst effect observed in Fe 3 GeTe 2 sheds light on the low-temperature application of two-dimensional layered materials in spin-caloritronics.

The transcription factor T-bet (Tbox protein expressed in T cells) is one of the master regulators of both the innate and adaptive immune responses. It plays a central role in T-cell lineage commitment, where it controls the T H 1 response, and in gene regulation in plasma B-cells and dendritic cells. T-bet is a member of the Tbox family of transcription factors; however, T-bet coordinately regulates the expression of many more genes than other Tbox proteins. A central unresolved question is how T-bet is able to simultaneously recognize distant Tbox binding sites, which may be located thousands of base pairs away. We have determined the crystal structure of the Tbox DNA binding domain (DBD) of T-bet in complex with a palindromic DNA. The structure shows a quaternary structure in which the T-bet dimer has its DNA binding regions splayed far apart, making it impossible for a single dimer to bind both sites of the DNA palindrome. In contrast to most other Tbox proteins, a single T-bet DBD dimer binds simultaneously to identical half-sites on two independent DNA. A fluorescence-based assay confirms that T-bet dimers are able to bring two independent DNA molecules into close juxtaposition. Furthermore, chromosome conformation capture assays confirm that T-bet functions in the direct formation of chromatin loops in vitro and in vivo. The data are consistent with a looping/synapsing model for transcriptional regulation by T-bet in which a single dimer of the transcription factor can recognize and coalesce distinct genetic elements, either a promoter plus a distant regulatory element, or promoters on two different genes.

The NAD-dependent DNA ligase is an excellent target for the discovery of antibacterial agents with a novel mode of action. In this work the DNA ligase from Streptococcus pneumoniae was investigated for its steady-state kinetic parameters and inhibition by compounds with an adenosine substructure. Inhibition by substrate DNA that was observed in the enzyme turnover experiments was verified by direct binding measurements using isothermal titration calorimetry (ITC). The substrate-inhibited enzyme form was identified as deadenylated DNA ligase. The binding potencies of 2-(butylsulfanyl) adenosine and 2-(cyclopentyloxy) adenosine were not significantly affected by the presence of the enzyme-bound DNA substrate. Finally, a mutant protein was prepared that was known to confer resistance to the adenosine compounds’ antibacterial activity. The mutant protein was shown to have little catalytic impairment yet it was less susceptible to adenosine compound inhibition.

Interfacial charge and strain distributions inside artificial perovskite ABO3 heterostructures often affect intriguing physical properties that are important to device performance. Normally, both charge and strain coexist across the interfaces, and their exact roles in determining the properties remain elusive. In the present work, La0.7Sr0.3MnO3 (LSMO) ultrathin films were grown on (001)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMNPT) single-crystal substrates to discriminate between the effect of charge and strain on the transport and magnetoelectric properties. In heterostructures with thicker LSMO films, the strain effect dominates the resistance and the magnetic moment depends on the external electric field. With the decreasing LSMO thickness, the butterfly-like resistance–electric-field (R-E) and magnetization–electric-field (M-E) curves become loop-like, indicating that charge effects dominate strain effects in determining the electric field that controls the transport and magnetic properties. Furthermore, soft-x-ray absorption spectra of 32 and 4 nm LSMO/PMNPT samples at the Mn L edge under an applied electric field of ±6 kV/cm indicate that orbital reconstruction also plays an important role in interfacial magnetoelectric coupling.Interfacial charge and strain distributions inside artificial perovskite ABO3 heterostructures often affect intriguing physical properties that are important to device performance. Normally, both charge and strain coexist across the interfaces, and their exact roles in determining the properties remain elusive. In the present work, La0.7Sr0.3MnO3 (LSMO) ultrathin films were grown on (001)-0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMNPT) single-crystal substrates to discriminate between the effect of charge and strain on the transport and magnetoelectric properties. In heterostructures with thicker LSMO films, the strain effect dominates the resistance and the magnetic moment depends on the external electric field. With the decreasing LSMO thickness, the butterfly-like resistance–electric-field (R-E) and magnetization–electric-field (M-E) curves become loop-like, indicating that charge effects dominate ...

Electric-field control of the anomalous Hall effect (AHE) was investigated in Fe40Pt60/(001)-Pb(Mg1/3Nb2/3)0.67Ti0.33O3 (FePt/PMN-PT) multiferroic heterostructures at room temperature. It was observed that a very large Hall resistivity change of up to 23.9% was produced using electric fields under a magnetic field bias of 100 Oe. A pulsed electric field sequence was used to generate nonvolatile strain to manipulate the Hall resistivity. Two corresponding nonvolatile states with distinct Hall resistivities were achieved after the electric fields were removed, thus enabling the encoding of binary information for memory applications. These results demonstrate that the Hall resistivity can be reversibly switched in a nonvolatile manner using programmable electric fields. Two remanent magnetic states that were created by electric-field-induced piezo-strain from the PMN-PT were attributed to the nonvolatile and reversible properties of the AHE. This work suggests that a low-energy-consumption-based approach can be used to create nonvolatile resistance states for spintronic devices based on electric-field control of the AHE.

Brightness and color are two basic visual features integrated by the human visual system (HVS) to gain a better understanding of color natural scenes. Aiming to combine these two cues to maximize the reliability of boundary detection in natural scenes, we propose a new framework based on the color-opponent mechanisms of a certain type of color-sensitive double-opponent (DO) cells in the primary visual cortex (V1) of HVS. This type of DO cells has oriented receptive field with both chromatically and spatially opponent structure. The proposed framework is a feedforward hierarchical model, which has direct counterpart to the color-opponent mechanisms involved in from the retina to V1. In addition, we employ the spatial sparseness constraint (SSC) of neural responses to further suppress the unwanted edges of texture elements. Experimental results show that the DO cells we modeled can flexibly capture both the structured chromatic and achromatic boundaries of salient objects in complex scenes when the cone inputs to DO cells are unbalanced. Meanwhile, the SSC operator further improves the performance by suppressing redundant texture edges. With competitive contour detection accuracy, the proposed model has the additional advantage of quite simple implementation with low computational cost.

A novel edge-preserving image decomposition based on saliency map is proposed to avoid halo phenomena in traditional image decompositions. Our method uses feature of saliency map that emphasizes salient edges in image to determine whether a region should be retained or processed, and then blur the image adaptively according to the local saliency average gradient. Experiments show that the proposed decomposition performs well in smoothing and enhancement. We compare our results with the guided filter and bilateral filter, and demonstrate a variety of applications including HDR and multi-scale enhancement.

This paper aims at presenting and testing a simple semi quantitative approach for mapping regional landslide susceptibility in the Wenchuan earthquake area, as shown in Fig. 1, using few key parameters and analytic hierarchy process (AHP) method. AHP is an expert-based method, which combines the numerical value with the intuitive experience. The validation of the method shows that the method is suitable for the landslide susceptibility assessment in the Wenchuan earthquake area.

In central and western regions where the topography is complex, various obstructions such as roads, rivers, and villages interfere the deployment of the mountain seismic line. In this paper, we compared the traditional operators, such as the Robert operator, the Sobel operator, and the Laplacian operator, discovering the defect in accuracy and noise resistance. Then, a computational approach using Canny detection with wavelet denoising has been proposed, which solves the problem of locating the seismic line accurately and efficiently.

Autoinducer inactivator A (AiiA) is a metal-dependent N-acyl homoserine lactone hydrolase that displays broad substrate specificity but shows a preference for substrates with long N-acyl substitutions. Previously, crystal structures of AiiA in complex with the ring-opened product N-hexanoyl-l-homoserine revealed binding interactions near the metal center but did not identify a binding pocket for the N-acyl chains of longer substrates. Here we report the crystal structure of an AiiA mutant, F107W, determined in the presence and absence of N-decanoyl-l-homoserine. F107 is located in a hydrophobic cavity adjacent to the previously identified ligand binding pocket, and the F107W mutation results in the formation of an unexpected interaction with the ring-opened product. Notably, the structure reveals a previously unidentified hydrophobic binding pocket for the substrate's N-acyl chain. Two aromatic residues, F64 and F68, form a hydrophobic clamp, centered around the seventh carbon in the product-bound structure's decanoyl chain, making an interaction that would also be available for longer substrates, but not for shorter substrates. Steady-state kinetics using substrates of various lengths with AiiA bearing mutations at the hydrophobic clamp, including insertion of a redox-sensitive cysteine pair, confirms the importance of this hydrophobic feature for substrate preference. Identifying the specificity determinants of AiiA will aid the development of more selective quorum-quenching enzymes as tools and as potential therapeutics.

Intrinsically rectifying-resistive switching (IR-RS) has been regarded as an effective way to address the crosstalk issue, due to the Schottky diodes formed at the metal/oxide interfaces in the ON states to suppress the sneak current at reverse biases. In this paper, the authors report for the first time another type of IR-RS that is related to the built-in homojunction. The IR-RS study is usually limited to macroscopic samples with micrometer-order pad-type electrodes, while this work is on NiO nanodots fabricated with ultrathin anodic-aluminum-oxide templates and acting as nanoscaled analogs of real devices. The NiO nanodots show high storage density and high uniformity, and the IR-RS behaviors are of good device performances in terms of retention, endurance, switching ratio, and rectification ratio. The feasibility of the IR-RS for selection device-free memory application is demonstrated by calculating the maximum crossbar array size under the worst-case scenario to be 3 Mbit.

The relationship between enzyme inhibition and antimicrobial potency of adenine-based NAD(+)-dependent DNA ligase (LigA) inhibitors was investigated using a strain of the Gram-negative pathogen Haemophilus influenzae lacking its major AcrAB-TolC efflux pump and the Gram-positive pathogen Streptococcus pneumoniae. To this end, biochemical inhibitors not mediating their antibacterial mode of action (MOA) via LigA were removed from the analysis. In doing so, a significant number of compounds were identified that acted via inhibition of LigA in S. pneumoniae but not in H. influenzae, despite being inhibitors of both isozymes. Deviations from the line correlating antimicrobial and biochemical potencies of LigA inhibitors with the correct MOA were observed for both species. These deviations, usually corresponding to higher MIC/IC50 ratios, were attributed to varying compound permeance into the cell.

Optimization of adenosine analog inhibitors of bacterial NAD(+)-dependent DNA ligase is discussed. Antibacterial activity against Streptococcus pneumoniae and Staphylococcus aureus was improved by modification of the 2-position substituent on the adenine ring and 3'- and 5'-substituents on the ribose. Compounds with logD values 1.5-2.5 maximized potency and maintained drug-like physical properties.