Nanoparticle-delivered RNAi-based pesticide target screening for the rice pest white-backed planthopper and risk assessment for a natural predator.

Vacuolar-type (H+)-ATPase (vATPase) is a conserved multi-subunit eukaryotic enzyme composed of 14 subunits that form a functional complex consisting of an ATP-hydrolytic domain (V1) and a proton-translocation domain (V0). ATP hydrolysis and subsequent H+ translocation rely heavily on a fully assembled V1/V0 complex. Since vATPase is crucial for insect survival, it is a viable molecular target for pest control. However, detailed functional analyses of the 14 subunits and their suitability for pest control have not been fully explored in a single insect species. In this study, we identified 22 vATPase subunit transcripts that correspond to 13 subunits (A1, A2, B, C, D, E, F, G, H, a1, a2, c and d) in the white-backed planthopper (WBPH), Sogatella furcifera, a major hemipteran pest of rice. RNAi screens using microinjection and spray-based methods revealed that the SfVHA-F, SfVHA-a2 and SfVHA-c2 subunits are critical. Furthermore, star polymer (SPc) nanoparticles were utilized to conduct spray-induced and nanoparticle-delivered gene silencing (SI-NDGS) to evaluate the pest control efficacy of RNAi targeting the SfVHA-F, SfVHA-a2 and SfVHA-c2 transcripts. Target mRNA levels and vATPase enzymatic activity were both reduced. Honeydew excreta was likewise reduced in WBPH treated with dsRNAs targeting SfVHA-F, SfVHA-a2 and SfVHA-c2. To assess the environmental safety of the nanoparticle-wrapped dsRNAs, Cyrtorhinus lividipennis Reuter, a major natural enemy of planthoppers, was also sprayed with dsRNAs targeting SfVHA-F, SfVHA-a2 and SfVHA-c2. Post-spray effects of dsSfVHA-a2 and dsSfVHA-c2 on C. lividipennis were innocuous. This study identifies SfVHA-a2 and SfVHA-c2 as promising targets for biorational control of WBPH and lays the foundation for developing environment-friendly RNAi biopesticides.

[Spatiotemporal Distribution and Risk Assessment of Pharmaceuticals in Typical Drinking Water Sources in the Middle Reaches of the Yangtze River].

The seasonal variation and spatial distribution of pharmaceuticals in typical drinking water sources in the middle reaches of the Yangtze River were analyzed using the solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry methods. Combined with the risk entropy method, the corresponding ecological risks for aquatic organisms were evaluated. The results showed that 80% of the target pharmaceuticals were detected in the drinking water sources, with average concentrations of 0.07-13.00 ng·L-1. The concentrations of the target pharmaceuticals were lower than or comparable with those in other drinking water sources reported in China. The spatiotemporal distribution of different pharmaceuticals varied. Generally, the detection level in winter was higher than that in summer, and there was no significant difference between that upstream and that downstream. This might be mainly attributed to seasonal/regional use and emissions of the pharmaceuticals, the impact of flow rate on dilution, and the impact of temperature on biodegradation. Compared with those before the COVID-19 epidemic, the detection concentrations of the target pharmaceuticals were relatively low. The reason for this might be that the prevention and control of the epidemic reduced the use and emission of the pharmaceuticals to a certain extent, and the high rainfall and runoff strengthened the dilution of water flow. The target pharmaceuticals, especially antibiotics, posed medium or low risks to aquatic organisms (especially algae). Considering the ecological risks and genotoxicity of pharmaceuticals and the potential risks of antibiotic-resistant genes, it is suggested to strengthen the investigation, evaluation, treatment, and control of pharmaceuticals in the water environment.

Pharmaceuticals in drinking water sources and tap water in a city in the middle reaches of the Yangtze River: occurrence, spatiotemporal distribution, and risk assessment.

The occurrence of ten target pharmaceuticals was investigated in drinking water sources and tap water in a city in the middle reaches of the Yangtze River, including erythromycin (ERY), roxithromycin (RTM), ciprofloxacin (CPX), ofloxacin (OFX), sulfadiazine (SDZ), sulfamethoxazole (SMX), oxytetracycline (OTC), tetracycline (TC), ibuprofen (IBF), and naproxen (NPX). And the corresponding ecological risk for three classes of aquatic organisms and human health risk for different life stages were estimated. Results demonstrated that nine pharmaceuticals except for TC were detected with the frequencies of 20-100% and the concentrations of

An efficient, economical, and easy mass production biochar supported zero-valent iron composite derived from direct-reduction natural goethite for Cu(II) and Cr(VI) remove.

In this study, a novel biochar-supported zero-valent iron (ZVI) composite was synthesised by a one-pot co-pyrolysis reduction method, and was used to remove Cu(II) and Cr(VI). The raw materials for the composite were derived from natural bagasse/straw and goethite. Scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, thermogravimetry (TG), and Brunauer-Emmett-Teller (BET) analysis were used to characterise the biochar and biochar-supported ZVI composites. Batch removal experiments on the effects of the initial pH and citric acid concentrations were performed as well as kinetic studies and isotherm experiments. The composite materials showed better Cu(II) and Cr(VI) removal performance than single biochar and mineral. The removal of Cu(II) and Cr(VI) is pH-dependent, and proceeds via heterogeneous multilayer chemisorption. Electrochemical analysis revealed that straw biochar-supported ZVI composite exhibited greater electrical conductivity and electron transfer rate than pure biochar and ZVI. FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) elucidated the uptake mechanism, showing that Cu(II) and Cr(VI) were easily adsorbed onto the biochar surface and were then reduced by ZVI. These results indicate that biochar-supported ZVI composite is effective for heavy metal remediation, which is economical, environment-friendly, and suitable for mass production.

Wearable Circuits Sintered at Room Temperature Directly on the Skin Surface for Health Monitoring.

A soft body area sensor network presents a promising direction in wearable devices to integrate on-body sensors for physiological signal monitoring and flexible printed circuit boards (FPCBs) for signal conditioning/readout and wireless transmission. However, its realization currently relies on various sophisticated fabrication approaches such as lithography or direct printing on a carrier substrate before attaching to the body. Here, we report a universal fabrication scheme to enable printing and room-temperature sintering of the metal nanoparticle on paper/fabric for FPCBs and directly on the human skin for on-body sensors with a novel sintering aid layer. Consisting of polyvinyl alcohol (PVA) paste and nanoadditives in the water, the sintering aid layer reduces the sintering temperature. Together with the significantly decreased surface roughness, it allows for the integration of a submicron-thick conductive pattern with enhanced electromechanical performance. Various on-body sensors integrated with an FPCB to detect health conditions illustrate a system-level example.

An improved beam splitting method for intensity modulated proton therapy.

The pencil beam algorithm (PBA) has become the predominant dose calculation method in proton therapy, due to its high level of efficiency. However, density heterogeneity decreases the accuracy of PBA. To improve PBA's accuracy, a beam splitting method is used to divide the original scanning beam into multiple thinner beamlets. Beam splitting should ensure that the beamlets' summed fluence is as close to the original beam fluence as possible, while keeping the spatial variance of beamlets small, and minimizing the number of beamlets. In this work, the generalized differential evolution (GDE) algorithm is utilized for the optimal scheme. Under reasonable constraints for the radius and weight of beamlets, several schemes are optimized via the GDE algorithm. In order to achieve a trade-off between accuracy and calculation speed, three hexagon-based schemes, which split the original beam into 7, 13, and 19 beamlets, respectively, are proposed and compared with the scheme of Raystation 4.5. The fluence distribution calculated by the schemes with 13 beamlets and 19 beamlets are demonstrated to be more accurate than the Raystation scheme, which has 19 beamlets, with a maximum absolute difference between the summed beamlets fluence and the original beam fluence of 2.12%, and 0.93%, respectively. Furthermore, beam splitting schemes are implemented into a proton dose calculation algorithm based on the KylinRay-IMPT TPS. These schemes, based on the dose algorithm, are compared with the Monte Carlo program TOPAS 3.2 in slab geometry with lateral heterogeneity. The dose, calculated by the dose algorithm using a scheme of 13 beamlets, shows a good agreement with the dose from TOPAS. In addition, an abdominal geometry is used for further verification. Gamma analysis passing rates greater than 99.7% are observed, with a 2%/2 mm criterion. Thus, the accuracy and effectiveness of the improved beam splitting method are preliminarily verified.

A Geant4-based Monte Carlo study of a benchtop multi-pinhole X-ray fluorescence computed tomography imaging.

BACKGROUND: X-ray fluorescence (XRF) computed tomography (XFCT) has shown promise for molecular imaging of metal nanoparticles such as gold nanoparticles (GNPs) and benchtop XFCT is under active development due to its easy access, low-cost instrumentation and operation. PURPOSE: To validate the performance of a Geant4-based Monte Carlo (MC) model of a benchtop multi-pinhole XFCT system for quantitative imaging of GNPs. METHODS: The MC mode consisted of a fan-beam x-ray source (125 kVp), which was used to stimulate the emission of XRF from the GNPs, a phantom (3 cm in diameter) which included six or nine inserts (3 mm in diameter), each of which contained the same (1 wt. %) or various (0.08-1 wt. %) concentrations of GNPs, a multi-pinhole collimator which could acquire multiple projections simultaneously and a one-sided or two-sided two-dimensional (2D) detector. Various pinhole diameters (3.7, 2, 1, 0.5 and 0.25 mm) and various particle numbers (20, 40, 80 and 100 billion) were simulated and the results for single pinhole and multi-pinhole (9 pinholes) imaging were compared. RESULTS: The image resolution for a 1 mm multi-pinhole was between 0.88 and 1.38 mm. The detection limit for multi-pinhole operation was about 0.09 wt. %, while that for the single pinhole was about 0.13 wt. %. For a fixed number of pinholes, noise increased with decreasing number of photons. CONCLUSION: The MC mode could acquire 2D slice images of the object without rotation and demonstrated that a multi-pinhole XFCT imaging system could be a potential bioimaging modality for nanomedical applications.

Leaf turgor loss point is correlated with drought tolerance and leaf carbon economics traits.

Leaf turgor loss point (πtlp) indicates the capacity of a plant to maintain cell turgor pressure during dehydration, which has been proven to be strongly predictive of the plant response to drought. In this study, we compiled a data set of πtlp for 1752 woody plant individuals belonging to 389 species from nine major woody biomes in China, along with reduced sample size of hydraulic and leaf carbon economics data. We aimed to investigate the variation of πtlp across biomes varying in water availability. We also tested two hypotheses: (i) πtlp predicts leaf hydraulic safety margins and (ii) it is correlated with leaf carbon economics traits. Our results showed that there was a positive relationship between πtlp and aridity index: biomes from humid regions had less negative values than those from arid regions. This supports the idea that πtlp may reflect drought tolerance at the scale of woody biomes. As expected, πtlp was significantly positively correlated with leaf hydraulic safety margins that varied significantly across biomes, indicating that this trait may be useful in modelling changes of forest components in response to increasing drought. Moreover, πtlp was correlated with a suite of coordinated hydraulic and economics traits; therefore, it can be used to predict the position of a given species along the 'fast-slow' whole-plant economics spectrum. This study expands our understanding of the biological significance of πtlp not only in drought tolerance, but also in the plant economics spectrum.

Coevolutionary Landscape of Kinase Family Proteins: Sequence Probabilities and Functional Motifs.

The protein kinase catalytic domain is one of the most abundant domains across all branches of life. Although kinases share a common core function of phosphoryl-transfer, they also have wide functional diversity and play varied roles in cell signaling networks, and for this reason are implicated in a number of human diseases. This functional diversity is primarily achieved through sequence variation, and uncovering the sequence-function relationships for the kinase family is a major challenge. In this study we use a statistical inference technique inspired by statistical physics, which builds a coevolutionary "Potts" Hamiltonian model of sequence variation in a protein family. We show how this model has sufficient power to predict the probability of specific subsequences in the highly diverged kinase family, which we verify by comparing the model's predictions with experimental observations in the Uniprot database. We show that the pairwise (residue-residue) interaction terms of the statistical model are necessary and sufficient to capture higher-than-pairwise mutation patterns of natural kinase sequences. We observe that previously identified functional sets of residues have much stronger correlated interaction scores than are typical.

Thrombocytopenia as a Preoperative Risk Assessment Tool in Patients With Rheumatic Heart Disease Undergoing Valve Replacement Surgery.

BACKGROUND: Postoperative thrombocytopenia has been reported to be correlated with adverse events, but the prognostic value of baseline thrombocytopenia is unclear. This study was undertaken to evaluate the relationship between preoperative thrombocytopenia and adverse outcomes in patients with rheumatic heart disease who underwent valve replacement surgery. METHODS AND RESULTS: A total of 1789 patients with rheumatic heart disease undergoing valve replacement surgery were consecutively enrolled and postoperatively followed up for 1 year. Patients were stratified on the basis of presence (n=495) or absence (n=1294) of thrombocytopenia (platelet count, <150×109/L), according to hospital admission platelet counts. During the hospitalization period, 69 patients (3.9%) died. The in-hospital all-cause mortality rate was significantly higher in the thrombocytopenic group (6.9% versus 2.7%; P<0.001). Multivariate analyses revealed that thrombocytopenia was independently associated with in-hospital all-cause mortality (odds ratio, 2.21; 95% confidence interval, 1.29-3.80; P=0.004). Platelet counts could predict in-hospital all-cause mortality for patients both with and without previous atrial fibrillation (areas under the curve, 0.708 [P<0.001] and 0.610 [P=0.025], respectively). One-year survival was significantly lower in patients with thrombocytopenia compared with controls (91.3% versus 96.1%; log-rank=14.65; P<0.001). In addition, thrombocytopenia was an independent predictor for postoperative 1-year all-cause mortality in multivariate Cox regression analysis. CONCLUSIONS: Platelet counts, as simple and inexpensive indexes, were reliable to be used as a preoperative risk assessment tool for patients with rheumatic heart disease undergoing valve replacement surgery.

Monte Carlo Simulation for Polychromatic X-Ray Fluorescence Computed Tomography with Sheet-Beam Geometry.

X-ray fluorescence computed tomography (XFCT) based on sheet beam can save a huge amount of time to obtain a whole set of projections using synchrotron. However, it is clearly unpractical for most biomedical research laboratories. In this paper, polychromatic X-ray fluorescence computed tomography with sheet-beam geometry is tested by Monte Carlo simulation. First, two phantoms (A and B) filled with PMMA are used to simulate imaging process through GEANT 4. Phantom A contains several GNP-loaded regions with the same size (10 mm) in height and diameter but different Au weight concentration ranging from 0.3% to 1.8%. Phantom B contains twelve GNP-loaded regions with the same Au weight concentration (1.6%) but different diameter ranging from 1 mm to 9 mm. Second, discretized presentation of imaging model is established to reconstruct more accurate XFCT images. Third, XFCT images of phantoms A and B are reconstructed by filter back-projection (FBP) and maximum likelihood expectation maximization (MLEM) with and without correction, respectively. Contrast-to-noise ratio (CNR) is calculated to evaluate all the reconstructed images. Our results show that it is feasible for sheet-beam XFCT system based on polychromatic X-ray source and the discretized imaging model can be used to reconstruct more accurate images.

Simulating Replica Exchange: Markov State Models, Proposal Schemes, and the Infinite Swapping Limit.

Replica exchange molecular dynamics is a multicanonical simulation technique commonly used to enhance the sampling of solvated biomolecules on rugged free energy landscapes. While replica exchange is relatively easy to implement, there are many unanswered questions about how to use this technique most efficiently, especially because it is frequently the case in practice that replica exchange simulations are not fully converged. A replica exchange cycle consists of a series of molecular dynamics steps of a set of replicas moving under different Hamiltonians or at different thermodynamic states followed by one or more replica exchange attempts to swap replicas among the different states. How the replica exchange cycle is constructed affects how rapidly the system equilibrates. We have constructed a Markov state model of replica exchange (MSMRE) using long molecular dynamics simulations of a host-guest binding system as an example, in order to study how different implementations of the replica exchange cycle can affect the sampling efficiency. We analyze how the number of replica exchange attempts per cycle, the number of MD steps per cycle, and the interaction between the two parameters affects the largest implied time scale of the MSMRE simulation. The infinite swapping limit is an important concept in replica exchange. We show how to estimate the infinite swapping limit from the diagonal elements of the exchange transition matrix constructed from MSMRE "simulations of simulations" as well as from relatively short runs of the actual replica exchange simulations.

Different leaf cost-benefit strategies of ferns distributed in contrasting light habitats of sub-tropical forests.

BACKGROUND AND AIMS: Ferns are abundant in sub-tropical forests in southern China, with some species being restricted to shaded understorey of natural forests, while others are widespread in disturbed, open habitats. To explain this distribution pattern, we hypothesize that ferns that occur in disturbed forests (FDF) have a different leaf cost-benefit strategy compared with ferns that occur in natural forests (FNF), with a quicker return on carbon investment in disturbed habitats compared with old-growth forests. METHODS: We chose 16 fern species from contrasting light habitats (eight FDF and eight FNF) and studied leaf functional traits, including leaf life span (LLS), specific leaf area (SLA), leaf nitrogen and phosphorus concentrations (N and P), maximum net photosynthetic rates (A), leaf construction cost (CC) and payback time (PBT), to conduct a leaf cost-benefit analysis for the two fern groups. KEY RESULTS: The two groups, FDF and FNF, did not differ significantly in SLA, leaf N and P, and CC, but FDF had significantly higher A, greater photosynthetic nitrogen- and phosphorus-use efficiencies (PNUE and PPUE), and shorter PBT and LLS compared with FNF. Further, across the 16 fern species, LLS was significantly correlated with A, PNUE, PPUE and PBT, but not with SLA and CC. CONCLUSIONS: Our results demonstrate that leaf cost-benefit analysis contributes to understanding the distribution pattern of ferns in contrasting light habitats of sub-tropical forests: FDF employing a quick-return strategy can pre-empt resources and rapidly grow in the high-resource environment of open habitats; while a slow-return strategy in FNF allows their persistence in the shaded understorey of old-growth forests.