The analysis on groundwater storage variations from GRACE/GRACE-FO in recent 20 years driven by influencing factors and prediction in Shandong Province, China.

Monitoring and predicting the regional groundwater storage (GWS) fluctuation is an essential support for effectively managing water resources. Therefore, taking Shandong Province as an example, the data from Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) is used to invert GWS fluctuation from January 2003 to December 2022 together with Watergap Global Hydrological Model (WGHM), in-situ groundwater volume and level data. The spatio-temporal characteristics are decomposed using Independent Components Analysis (ICA), and the impact factors, such as precipitation and human activities, which are also analyzed. To predict the short-time changes of GWS, the Support Vector Machines (SVM) is adopted together with three commonly used methods Long Short-Term Memory (LSTM), Singular Spectrum Analysis (SSA), Auto-Regressive Moving Average Model (ARMA), as the comparison. The results show that: (1) The loss intensity of western GWS is significantly greater than those in coastal areas. From 2003 to 2006, GWS increased sharply; during 2007 to 2014, there exists a loss rate - 5.80 ± 2.28 mm/a of GWS; the linear trend of GWS change is - 5.39 ± 3.65 mm/a from 2015 to 2022, may be mainly due to the effect of South-to-North Water Diversion Project. The correlation coefficient between GRACE and WGHM is 0.67, which is consistent with in-situ groundwater volume and level. (2) The GWS has higher positive correlation with monthly Global Precipitation Climatology Project (GPCP) considering time delay after moving average, which has the similar energy spectrum depending on Continuous Wavelet Transform (CWT) method. In addition, the influencing facotrs on annual GWS fluctuation are analyzed, the correlation coefficient between GWS and in-situ data including the consumption of groundwater mining, farmland irrigation is 0.80, 0.71, respectively. (3) For the GWS prediction, SVM method is adopted to analyze, three training samples with 180, 204 and 228 months are established with the goodness-of-fit all higher than 0.97. The correlation coefficients are 0.56, 0.75, 0.68; RMSE is 5.26, 4.42, 5.65 mm; NSE is 0.28, 0.43, 0.36, respectively. The performance of SVM model is better than the other methods for the short-term prediction.

Phase-amplitude reduction and optimal phase locking of collectively oscillating networks.

We present a phase-amplitude reduction framework for analyzing collective oscillations in networked dynamical systems. The framework, which builds on the phase reduction method, takes into account not only the collective dynamics on the limit cycle but also deviations from it by introducing amplitude variables and using them with the phase variable. The framework allows us to study how networks react to applied inputs or coupling, including their synchronization and phase locking, while capturing the deviations of the network states from the unperturbed dynamics. Numerical simulations are used to demonstrate the effectiveness of the framework for networks composed of FitzHugh-Nagumo elements. The resulting phase-amplitude equations can be used in deriving optimal periodic waveforms or introducing feedback control for achieving fast phase locking while stabilizing the collective oscillations.

Self-induced-stochastic-resonance breathing chimeras.

The study by Semenova et al. [Phys. Rev. Lett. 117, 014102 (2016)0031-900710.1103/PhysRevLett.117.014102] discovered a type of chimera state known as coherence-resonance chimera (CRC), which combines the effects of coherence resonance (CR) and the spatial property of classical chimeras. In this Letter, we present yet another form of chimera, which we refer to as self-induced-stochastic-resonance breathing chimera (SISR-BC), which differs fundamentally from the CRC in that it combines the mechanism and effects of self-induced stochastic resonance (SISR, previously shown by DeVille et al. [Phys. Rev. E 72, 031105 (2005)1539-375510.1103/PhysRevE.72.031105] to be intrinsically different from CR), the symmetry breaking in the rotational coupling between the slow and fast subsystems of the coupled oscillators, and the property of breathing chimera-a form of chimera state characterized by nonstationary periodic dynamics of coherent-incoherent patterns with a periodically oscillating global order parameter. Unlike other types of chimeras, including CRC, SISR-BC demonstrates remarkable resilience to a relatively wide range of stochastic perturbations and persists even when the purely excitable system is significantly distant from the Hopf bifurcation threshold-thanks to the mechanism of SISR-and globally attracts random distributions of initial conditions. Considering its potential impact on information processing in neuronal networks, SISR-BC could have special significance and applications.

Algal organic matter inhibits methylmercury photodegradation in eutrophic lake water: A dynamic study.

Algal organic matter (AOM) is a major component of dissolved organic matter (DOM) in eutrophic lakes and could impact the photodegradation of neurotoxic methylmercury (MeHg) in water. Predicting these effects, however, is challenging, largely due to the dynamic changes of AOM during algal decomposition. Here, we investigated the effects of AOM on MeHg photodegradation throughout the algal decomposition process and elucidated these effects by characterizing dynamic changes of AOM and exploring the respective roles of various reactive oxygen species (ROS). Our results reveal that AOM derived from algal decomposition significantly inhibits MeHg photodegradation, and the extent of this inhibition varies depending on the specific lakes (8-21 %, p < 0.05) and their eutrophication states (16-28 %, p < 0.05). The inhibitory effect gradually weakened as the decomposition progressed, which may be attributed to the dynamic changes in the quantity and quality of AOM. Moreover, hydroxyl radical (·OH) was found to be the main contributor in driving MeHg photodegradation (15-23 %) during the early stages of decomposition (day 0-3), while in the later stage (day 12-24), the role of singlet oxygen (1O2, 15-20 %) and (3DOM*, 21-30 %) gradually strengthened and these three ROS jointly drove MeHg photodegradation. Based on our findings and recent studies, we propose that AOM derived from algal decomposition plays a vital role in increasing the risk of MeHg in eutrophic lakes. It promotes MeHg formation while simultaneously inhibiting its photodegradation. Integrating AOM-MeHg interactions into Hg biogeochemical cycling models would reduce uncertainties when predicting MeHg risks.

High-responsivity dual-band ultraviolet photodetector based on Ga2O3/GaN heterostructure.

Ultraviolet photodetectors have aroused wide concern based on wide-band-gap semiconductors, such as GaN and Ga2O3. Exploiting multi-spectral detection provides unparalleled driving force and direction for high-precision ultraviolet detection. Here we demonstrate an optimized design strategy of Ga2O3/GaN heterostructure bi-color ultraviolet photodetector, which presents extremely high responsivity and UV-to-visible rejection ratio. The electric field distribution of optical absorption region was profitably modified by optimizing heterostructure doping concentration and thickness ratio, thus further facilitating the separation and transport of photogenerated carriers. Meanwhile, the modulation of Ga2O3/GaN heterostructure band offset leads to the fluent transport of electrons and the blocking of holes, thereby enhancing the photoconductive gain of the device. Eventually, the Ga2O3/GaN heterostructure photodetector successfully realizes dual-band ultraviolet detection and achieves high responsivity of 892/950 A/W at the wavelength of 254/365 nm, respectively. Moreover, UV-to-visible rejection ratio of the optimized device also keeps at a high level (∼103) while exhibiting dual-band characteristic. The proposed optimization scheme is anticipated to provide significant guidance for the reasonable device fabrication and design on multi-spectral detection.

Pollen self-elimination CRISPR-Cas genome editing prevents transgenic pollen dispersal in maize.

This study reports the development of a programmed pollen self-elimination CRISPR-Cas (PSEC) system in which the pollen is infertile when PSEC is present in haploid pollen. PSEC can be inherited through the female gametophyte and retains genome editing activity in vivo across generations. This system could greatly alleviate serious concerns about the widespread diffusion of genetically modified (GM) elements into natural and agricultural environments via outcrossing.

CRISPR/dCas-mediated gene activation toolkit development and its application for parthenogenesis induction in maize.

Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems can be engineered as programmable transcription factors to either activate (CRISPRa) or inhibit transcription. Apomixis is extremely valuable for the seed industry in breeding clonal seeds with pure genetic backgrounds. We report here a CRISPR/dCas9-based toolkit equipped with dCas9-VP64 and MS2-p65-HSF1 effectors that may specifically target genes with high activation capability. We explored the application of in vivo CRISPRa targeting of maize BABY BOOM2 (ZmBBM2), acting as a fertilization checkpoint, as a means to engineer parthenogenesis. We detected ZmBBM2 transcripts only in egg cells but not in other maternal gametic cells. Activation of ZmBBM2 in egg cells in vivo caused maternal cell-autonomous parthenogenesis to produce haploid seeds. Our work provides a highly specific gene-activation CRISPRa technology for target cells and verifies its application for parthenogenesis induction in maize.

Noise-tuned bursting in a Hedgehog burster.

Noise can shape the firing behaviors of neurons. Here, we show that noise acting on the fast variable of the Hedgehog burster can tune the spike counts of bursts via the self-induced stochastic resonance (SISR) phenomenon. Using the distance matching condition, the critical transition positions on the slow manifolds can be predicted and the stochastic periodic orbits for various noise strengths are obtained. The critical transition positions on the slow manifold with non-monotonic potential differences exhibit a staircase-like dependence on the noise strength, which is also revealed by the stepwise change in the period of the stochastic periodic orbit. The noise-tuned bursting is more coherent within each step while displaying mixed-mode oscillations near the boundaries between the steps. When noise is large enough, noise-induced trapping of the slow variable can be observed, where the number of coexisting traps increases with the noise strength. It is argued that the robustness of SISR underlies the generality of the results discovered in this paper.

A field-deployable method for single and multiplex detection of DNA or RNA from pathogens using Cas12 and Cas13.

For some Cas nucleases, trans-cleavage activity triggered by CRISPR/Cas-mediated cis-cleavage upon target nucleic acid recognition has been explored for diagnostic detection. Portable single and multiplex nucleic acid-based detection is needed for crop pathogen management in agriculture. Here, we harnessed and characterized RfxCas13d as an additional CRISPR/Cas nucleic acid detection tool. We systematically characterized AsCas12a, LbCas12a, LwaCas13a, and RfxCas13d combined with isothermal amplification to develop a CRISPR/Cas nucleic acid-based tool for single or multiplex pathogen detection. Our data indicated that sufficient detection sensitivity was achieved with just a few copies of DNA/RNA targets as input. Using this tool, we successfully detected DNA from Fusarium graminearum and Fusarium verticillioides and RNA from rice black-streaked dwarf virus in crude extracts prepared in the field. Our method, from sample preparation to result readout, could be rapidly and easily deployed in the field. This system could be extended to other crop pathogens, including those that currently lack a detection method and have metabolite profiles that make detection challenging. This nucleic acid detection system could also be used for single-nucleotide polymorphism genotyping, transgene detection, and qualitative detection of gene expression in the field.

Algal Organic Matter Drives Methanogen-Mediated Methylmercury Production in Water from Eutrophic Shallow Lakes.

Algal blooms bring massive amounts of algal organic matter (AOM) into eutrophic lakes, which influences microbial methylmercury (MeHg) production. However, because of the complexity of AOM and its dynamic changes during algal decomposition, the relationship between AOM and microbial Hg methylators remains poorly understood, which hinders predicting MeHg production and its bioaccumulation in eutrophic shallow lakes. To address that, we explored the impacts of AOM on microbial Hg methylators and MeHg production by characterizing dissolved organic matter with Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy and quantifying the microbial Hg methylation gene hgcA. We first reveal that the predominance of methanogens, facilitated by eutrophication-induced carbon input, could drive MeHg production in lake water. Specifically, bioavailable components of AOM (i.e., CHONs such as aromatic proteins and soluble microbial byproduct-like materials) increased the abundances (Archaea-hgcA gene: 438-2240% higher) and activities (net CH4 production: 16.0-44.4% higher) of Archaea (e.g., methanogens). These in turn led to enhanced dissolved MeHg levels (24.3-15,918% higher) for three major eutrophic shallow lakes in China. Nevertheless, our model results indicate that AOM-facilitated MeHg production could be offset by AOM-induced MeHg biodilution under eutrophication. Our study would help reduce uncertainties in predicting MeHg production, providing a basis for mitigating the MeHg risk in eutrophic lakes.

Unified mechanism of inverse stochastic resonance for monostability and bistability in Hindmarsh-Rose neuron.

Noise is ubiquitous and has been verified to play constructive roles in various systems, among which the inverse stochastic resonance (ISR) has aroused much attention in contrast to positive effects such as stochastic resonance. The ISR has been observed in both bistable and monostable systems for which the mechanisms are revealed as noise-induced biased switching and noise-enhanced stability, respectively. In this paper, we investigate the ISR phenomenon in the monostable and bistable Hindmarsh-Rose neurons within a unified framework of large deviation theory. The critical noise strengths for both cases can be obtained by matching the timescales between noise-induced boundary crossing and the limit cycle. Furthermore, different stages of ISR are revealed by the bursting frequency distribution, where the gradual increase of the peak bursting frequency can also be explained within the same framework. The perspective and results in this paper may shed some light on the understanding of the noise-induced complex phenomena in stochastic dynamical systems.

Establishment of an efficient seed fluorescence reporter-assisted CRISPR/Cas9 gene editing in maize.

Genome editing by clustered regularly interspaced short palindromic sequences (CRISPR)/CRISPR-associated protein 9 (Cas9) has revolutionized functional gene analysis and genetic improvement. While reporter-assisted CRISPR/Cas systems can greatly facilitate the selection of genome-edited plants produced via stable transformation, this approach has not been well established in seed crops. Here, we established the seed fluorescence reporter (SFR)-assisted CRISPR/Cas9 systems in maize (Zea mays L.), using the red fluorescent DsRED protein expressed in the endosperm (En-SFR/Cas9), embryos (Em-SFR/Cas9), or both tissues (Em/En-SFR/Cas9). All three SFRs showed distinct fluorescent patterns in the seed endosperm and embryo that allowed the selection of seeds carrying the transgene of having segregated the transgene out. We describe several case studies of the implementation of En-SFR/Cas9, Em-SFR/Cas9, and Em/En- SFR/Cas9 to identify plants not harboring the genome-editing cassette but carrying the desired mutations at target genes in single genes or in small-scale mutant libraries, and report on the successful generation of single-target mutants and/or mutant libraries with En-SFR/Cas9, Em-SFR/Cas9, and Em/En-SFR/Cas9. SFR-assisted genome editing may have particular value for application scenarios with a low transformation frequency and may be extended to other important monocot seed crops.

Distribution of Nitrogen and Phosphorus in Pore Water Profiles and Estimation of Their Diffusive Fluxes and Annual Loads in Guanting Reservoir (GTR), Northern China.

Improvement of water quality has frequently been delayed due to high recycling rates of nutrients across the sediment-water interface in a reservoir. Diffusive fluxes and annual loads of ammonia nitrogen (NH4+-N) and phosphate (PO43--P) in sediments from Guanting Reservoir (GTR) were estimated according to their vertical distribution. The average contents of NH4+-N and PO43--P in surface pore water were higher by factors of 6.9 - 11.7 and 1.3 - 6.4 than those in overlying water, respectively. The ranges of fluxes were 1.59 - 13.0 (mg m2 d-1) for NH4+-N, and 0.002 - 0.196 (mg m2 d-1) for PO43--P. The annual load contributions from sediments of GTR were 659 t a-1 for NH4+-N and 4.83 t a-1 for PO43--P. Notably, the upstream of GTR accounted for 50.7% annual loads for NH4+-N, while the downstream contributed 71.2% loads to PO43--P. This study will better inform future environmental management for the reservoir.

Genome Editing Enables Next-Generation Hybrid Seed Production Technology.

The next-generation hybrid seed technology enables the successful production of sortable hybrid seeds from genic male sterile (GMS) lines and maintainers; however, it requires multiple laborious and complicated steps. Here, we designed a simple next-generation hybrid seed production strategy that takes advantage of the CRISPR/Cas9 technology to create a Manipulated GMS Maintainer (MGM) system via a single transformation. Under this schema, the maize male fertility gene ZmMS26 was nullified by removal of its fifth exon using the CRISPR/Cas9 system on a vector, and a second vector carrying a functional ZmMS26 cDNA was co-transformed to restore fertility. The second vector also contains a male gametophyte inactivation gene (ZmAA1) encoding maize α-amylase driven by the pollen-specific promoter PG47 and an endosperm fluorescent marker (DsRED) driven by the barley endosperm aleurone-specific promoter Ltp2. The derived single-copy hemizygous MGM lines bore a mutated MS26 gene, leading to complete male sterility but normal vegetative growth and grain yield. The MGM system could prevent genetic transmission of the MGM elements via male gametophytes, providing an efficient method for sorting maintainer seeds labeled by DsRED. This strategy can be extended to any GMS gene and to hybrid crops other than maize.

Phase reduction for FitzHugh-Nagumo neuron with large timescale separation.

Phase reduction approach is a useful tool to reduce the dimension of limit-cycle oscillators. In this paper, it is applied to the FitzHugh-Nagumo neuron model with large timescale separation. To quantitate the response of the oscillator to the external perturbations, the asymptotic behaviors of the phase sensitivity functions for fast and slow variables are obtained. It is shown that in the relaxation limit, apart from the jump points which are the vertices of the cubic nullcline, the phase is insensitive to the perturbations on the fast variable. By using the phase sensitivity functions, two cases, namely, periodic pulse train perturbation and common noise perturbation, are investigated. Theoretical and numerical results suggest better performance for the synchronization behaviors of the perturbations on the slow variable for large timescale separation.

Maize WI5 encodes an endo-1,4-ß-xylanase required for secondary cell wall synthesis and water transport in xylem.

Water transport from roots to leaves through xylem is important for plant growth and development. Defects in water transport can cause drought stress, even when there is adequate water in the soil. Here, we identified the maize (Zea mays) wilty5 (wi5) mutant, which exhibits marked dwarfing and leaf wilting throughout most of its life cycle under normal growth conditions. wilty5 seedlings exhibited lower xylem conductivity and wilted more rapidly under drought, NaCl, and high temperature treatments than wild-type plants. Map-based cloning revealed that WI5 encodes an active endo-1,4-ß-xylanase from glycosyl dehydration family 10, which mainly functions in degrading and reorganizing cell wall xylan. Reverse-transcription polymerase chain reaction and ß-glucuronidase assays revealed that WI5 is highly expressed in stems, especially in internodes undergoing secondary wall assembly. RNA sequencing suggested that WI5 plays a unique role in internode growth. Immunohistochemistry and electron microscopy confirmed that wi5 is defective in xylan deposition and secondary cell wall thickening. Lignin deposition and xylan content were markedly reduced in wi5 compared to the wild-type plants. Our results suggest that WI5 functions in xylem cell wall thickening through its xylanase activity and thereby regulates xylem water transport, the drought stress response, and plant growth in maize.

Sorption kinetics of parent and substituted PAHs for low-density polyethylene (LDPE): Determining their partition coefficients between LDPE and water (KLDPE) for passive sampling.

Low-density polyethylene (LDPE) has been widely used as a sorbent for passive sampling of hydrophobic organic contaminants (HOCs) in aquatic environments. However, it has seen only limited application in passive sampling for measurement of freely dissolved concentrations of parent and substituted PAHs (SPAHs), which are known to be toxic, mutagenic and carcinogenic. Here, the 16 priority PAHs and some typical PAHs were selected as target compounds and were simultaneously determined by gas chromatography-mass spectrometer (GC-MS). Some batch experiments were conducted in the laboratory to explore the adsorption kinetics of the target compounds in LDPE membranes. The results showed that both PAHs and SPAHs could reach equilibrium status within 19-38 days in sorption kinetic experiments. The coefficients of partitioning between LDPE film (50 µm thickness) and water (KLDPE) for the 16 priority PAHs were in good agreement with previously reported values, and the values of KLDPE for the 9 SPAHs are reported in this study for the first time. Significant linear relationships were observed, i.e., log KLDPE = 0.705 × log KOW + 1.534 for PAHs (R2 = 0.8361, p < 0.001) and log KLDPE = 0.458 × log KOW + 3.092 for SPAHs (R2 = 0.5609, p = 0.0077). The selected LDPE film was also proven to meet the condition of "zero sink" for the selected target compounds. These results could provide basic support for the configuration and in situ application of passive samplers.