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Whipple shield, a dual-wall system, as well as its improved structures, is widely applied to defend the hypervelocity impact of space debris (projectile). This paper reviews the studies about the mechanism and process of protection against hypervelocity impacts using Whipple shield. Ground-based experiment and numerical simulation for hypervelocity impact and protection are introduced briefly. Three steps of the Whipple shield protection are discussed in order, including the interaction between the projectile and bumper, the movement and diffusion of the debris cloud, and the interaction between the debris cloud and rear plate. Potential improvements of the protection performance focusing on these three steps are presented. Representative works in the last decade are mentioned specifically. Some prospects and suggestions for future studies are put forward.

Freezing-induced groundwater-level decline is widely observed in regions with a shallow water table, but many existing studies on freezing-induced groundwater migration do not account for freezing-induced water-level fluctuations. Here, by combining detailed field observations of liquid soil water content and groundwater-level fluctuations at a site in the Ordos Plateau, China, and numerical modeling, we showed that the interaction of soil water and groundwater dynamics was controlled by wintertime atmospheric conditions and topographically driven lateral groundwater inflow. With an initial water table depth of 120 cm and a lateral groundwater inflow rate of 1.03 mm d−1, the observed freezing and thawing-induced fluctuations of soil water content and groundwater level are well reproduced. By calculating the budget of groundwater, the mean upward flux of freezing-induced groundwater loss is 1.46 mm d−1 for 93 d, while the mean flux of thawing-induced groundwater recharge is as high as 3.94 mm d−1 for 32 d. These results could be useful for local water resources management when encountering seasonally frozen soils and for future studies on two- or three-dimensional transient groundwater flow in semi-arid and seasonally frozen regions. By comparing models under a series of conditions, we found the magnitude of freezing-induced groundwater loss decreases with initial water table depth and increases with the rate of groundwater inflow. We also found a fixed-head lower boundary condition would overestimate freezing-induced groundwater migration when the water table depth is shallow. Therefore, an accurate characterization of freezing-induced water table decline is critical to quantifying the contribution of groundwater to hydrological and ecological processes in cold regions.

Tomato is more prone to Tuta absoluta invasion and damages as compared to other host plants but the mechanism behind this preference has not been elucidated. Here, two contrasting host preference plants, tomato and eggplant, were used to investigate biochemical and transcriptomic modifications induced by T. absoluta infestation. Biochemical analysis at 0–72 h post T. absoluta infestation revealed significantly reduced concentrations of amino acid, fructose, sucrose, jasmonic acid, salicylic acid, and total phenols in tomato compared to eggplant, mainly at 48 h post T. absoluta infestation. Transcriptome analysis showed higher transcript changes in infested eggplant than tomato. Signaling genes had significant contributions to mediate plant immunity against T. absoluta, specifically genes associated with salicylic acid in eggplant. Genes from PR1b1, NPR1 , NPR3, MAPKs , and ANP1 families play important roles to mitigate T. absoluta infestation. Our results will facilitate the development of control strategies against T. absoluta for sustainable tomato production.

The polarization effect has been a powerful tool in controlling the morphology of metal nanoparticles. However, a precise investigation of the polarization effect has been a challenging pursuit for a long time, and little has been achieved for analysis at the atomic level. Here the atomic-level analysis of the polarization effect in controlling the morphologies of metal nanoclusters is reported. By simply regulating the counterions, the controllable transformation from Pt1Ag28(S-PhMe2)x(S-Adm)18−x(PPh3)4 (x = 0–6, Pt1Ag28-2) to Pt1Ag24(S-PhMe2)18 (Pt1Ag24) with a spherical configuration or to Pt1Ag28(S-Adm)18(PPh3)4 (Pt1Ag28-1) with a tetrahedral configuration has been accomplished. In addition, the spherical or tetrahedral configuration of the clusters could be reversibly transformed by re-regulating the proportion of counterions with opposite charges. More significantly, the configuration transformation rate has been meticulously manipulated by regulating the polarization effect of the ions on the parent nanoclusters. The observations in this paper provide an intriguing nanomodel that enables the polarization effect to be understood at the atomic level., Based on the inter-conversion between Pt1Ag24(SR)18 and Pt1Ag28(SR)18(PPh3)4, an insight into the polarization effect in controlling the morphology of metal nanoparticles is presented.

Background Thermotolerant yeast has outstanding potential in industrial applications. Komagataella phaffii (Pichia pastoris) is a common cell factory for industrial production of heterologous proteins. Results Herein, we obtained a thermotolerant K. phaffii mutant G14 by mutagenesis and adaptive evolution. G14 exhibited oxidative and thermal stress cross-tolerance and high heterologous protein production efficiency. The reactive oxygen species (ROS) level and lipid peroxidation in G14 were reduced compared to the parent. Oxidative stress response (OSR) and heat shock response (HSR) are two major responses to thermal stress, but the activation of them was different in G14 and its parent. Compared with the parent, G14 acquired the better performance owing to its stronger OSR. Peroxisomes, as the main cellular site for cellular ROS generation and detoxification, had larger volume in G14 than the parent. And, the peroxisomal catalase activity and expression level in G14 was also higher than that of the parent. Excitingly, the gene knockdown of CAT encoding peroxisomal catalase by dCas9 severely reduced the oxidative and thermal stress cross-tolerance of G14. These results suggested that the augmented OSR was responsible for the oxidative and thermal stress cross-tolerance of G14. Nevertheless, OSR was not strong enough to protect the parent from thermal stress, even when HSR was initiated. Therefore, the parent cannot recover, thereby inducing the autophagy pathway and resulting in severe cell death. Conclusions Our findings indicate the importance of peroxisome and the significance of redox balance in thermotolerance of yeasts.

Alloyed green-emitting CdZnSeS/ZnS quantum dots (QDs) demonstrate potential applications in solid-state lighting and displays owing to their various advantages, such as high color purity, light conversion efficiency, and color rendering index. However, their applications in white light-emitting diodes (WLEDs) are limited by their poor photostabilities on blue-emitting gallium nitride (GaN) LED chips. In this study, the effect of the specific surface area (SSA) in the coating layers on the photostabilities of QDs was investigated. SSA was adjusted by controlling the proportions of dense aluminum oxide (AlOX) layers and porous silica dioxide (SiO2) layers to fabricate QD protective layers via a catalyst-free sol-gel method. The results showed that the synthesized AlOX possessing the lowest SSA among the synthesis protective layers presented the best QD photostabilities on the LED chips. Moreover, they exhibited a 9.9-fold increase in the operational lifetime (T80) compared to that of pristine QDs. In addition, the QD-based WLED achieved an excellent display performance with a wide color gamut (115%) of the National Television System Committee (NTSC) color gamut standard. This approach offers a promising strategy for enhancing the QD photostabilities for applications in solid-state lighting and displays by coating the protective layers on the QD surface.

Recently, the free element method(FREM), a novel strong-form method, is successfully used to solve thermal and mechanical problems. However, similar to some other strong-form methods, it is difficult to handle the geometric model with corner points. To overcome this weakness, the zonal free element method (ZFREM), which has strong adaptability to deal with complex geometry, is proposed by introducing the sub-domain mapping technique. Besides, the proposed method is firstly applied to solve piezoelectric problems. A unified formulation for piezoelectric problems in the case of electro-mechanical coupling field is established by the zonal free element method. Several two-dimensional (2D) and three-dimensional (3D) examples are carried out and the results are compared with available analytical solutions and finite element solutions to demonstrate validity and accuracy of the proposed method.

Underground space utilization is becoming increasingly essential for modern metropolitan cities such as Singapore. Mapping a soil/rock interface using traditional borehole investigation methods is expensive and difficult, owing to the numerous physical constraints within a built-up city. Boreholes are often far apart, resulting in many unforeseen ground conditions during subsequent excavation. Geophysical methods are sometimes employed as possible alternatives for fast, economical, and efficient bedrock surveys. The goal of this study is to investigate the practical details of applying microtremor array measurement (MAM) as a non-invasive surface wave survey for mapping soil/rock interfaces in Singapore. Critical configurations in field data acquisition are examined, and practical recommendations for array construction are provided. In addition, 30 in situ MAM tests are carried out for two major geological formations in Singapore. From the results, a standard shear wave velocity (Vs) of 500 m/s is found to be suitable for interpreting the soil/rock interface, for the Bukit Timah Granite and Jurong formations. However, the method does not predict well when soft Kallang formation deposits are present. Other limitations are also discussed in the later parts of this paper. Conclusions and practical recommendations are discussed, providing constructive guidance to the industry. The proposed Vs-based method and associated guidelines and limitations can be used to create a digital geological database and are especially useful for rock profiling in an urban environment.

The low temperature of sewage in north China results in low performance of biological treatment at municipal wastewater treatment plants (MWTPs), especially in biological nitrogen removal. A modified two-stage A/O process with an embedded biofilm was proposed to enhance nitrogen removal. The operation performance of a pilot test was compared with an A2/O and SBR process at existing MWTPs to investigate the resistance to low temperature. The microbial communities for the three processes were compared based on the metagenomics results of 16sDNA high-throughput sequencing from activated sludge. The modified A/O resulted in a higher average removal of COD (90.12%) than A2/O (85.23%) and SBR (83.03%), especially of small-molecule organic compounds ( 5 k Da); the TN removal rate of A2/O, SBR and the modified A/O was also increased from 74.47%, 70.63% and 78.46%, respectively. High-throughput sequencing revealed increased microbial diversity and an abundance of denitrifying functional bacteria was observed in the modified A/O process at low temperatures. The abundance of nitrite oxidation bacteria (NOB) including Nitrosomonas and Nitrospira, the amount was 1.76% and 2.34% in modified A/O, respectively, whereas NOB only accounted for 1.82% in A2/O and 1.35% in SBR.

Al–TiO2–C–La2O3 refiners were synthesized by the in-situ exothermic dispersion method using TiO2, C, Al and La2O3 powders as raw materials. Scanning electron microscopy equipped with energy dispersive X-ray spectrometry and X-ray diffraction were used to investigate the microstructures of the Al–TiO2–C–La2O3 refiners. Commercial pure aluminum was refined by the Al–TiO2–C–La2O3 refiners, aimed at investigating refining performance and the resistance to recession. The results show that the Al–TiO2– C–La2O3 refiner with 0.2% La2O3 is composed of α-Al, blocky Al3Ti, dispersive Al2O3 and TiC, which has a better refining effect on commercial pure aluminum than the Al– TiO2–C refiner. The average grain size refined by the above refiner is about 80 μm and it performs better and has a longer refining effect. The grain structure refined by Al–TiO2– C–La2O3 becomes finer within 5 min and remains the same after 120 min, while refined by the Al–TiO2–C refiner the equivalent times are 10 min and 30 min respectively.

The determination of active sites in metal nanoclusters is of great significance for the in-depth understanding of the structural evolution and the mechanism of physicochemical properties. In this work, the surface active Ag2(SR)3 units of the Ag48Cl14(S-Adm)30 nanocluster are determined, and the active-site tailoring of this nanocluster gives rise to two derivative nanoclusters, i.e., the structure-maintained Ag48Cl14(S-Adm)26(S-c-C6H11)4 and the structure-growth Ag50Cl16(S-Adm)28(DPPP)2. Both Ag48 and Ag50 nanoclusters exhibit almost the same cluster framework, but the Ag2(S-Adm)3 active units are regulated to Ag3(S-Adm)2(DPPP)1Cl1 with the transformation from Ag48 to Ag50. The surface active sites on Ag48 are rationalized by analyzing its crystal structure and the ligand-exchange-induced cluster transformation. This study provides some inspiration toward the active-site tailoring of nanocluster surface structures, which is significant for the preparation of new cluster-based nanomaterials with customized structures and enhanced performance.

This study investigated the feasibility of using the mineral element contents and 87Sr/86Sr ratios of blueberries to trace their origins. The contents of 28 mineral elements, including K, Al, and Mg, were determined in 104 blueberry samples from three blueberry-producing areas in Guizhou Province, China. Also determined were both the 87Sr/86Sr ratios in 48 blueberry samples as well as the type of soil in which the blueberries were grown. Cluster analysis of 87Sr/86Sr ratios, stepwise discriminant analysis of mineral element contents, and combined discriminant analyses of 87Sr/86Sr ratios and mineral element contents were done. The results show that ten elements (Ca, Cr, Cs, Mg, Mn, P, Rb, Sb, Th, and Y) were selected by linear discriminant analysis, which could be used to establish the provenance traceability model of blueberries in Guizhou. The original accuracy of linear discriminant analysis was 89.4%, and the accuracy of cross-validation was 83.6%. When 87Sr/86Sr ratios were used for tracing, the accuracies of both the original discrimination and the cross-validation were 81.3% as determined by linear discriminant analysis, and the accuracy rate of origin discrimination was 81.25% by cluster analysis. The results of combined discrimination were the best: the accuracy of the original discrimination was 95.8%, and the accuracy of cross-validation was 93.8%. Mineral element contents and 87Sr/86Sr ratios can be used to trace the origins of blueberries, and combining them can significantly improve the discrimination accuracy. Fisher linear discriminant analysis had the greatest accuracy followed by cluster analysis, while principal component analysis was relatively poor in the research of Guizhou blueberry origin traceability.

Efficient destruction of cyanide by thermal decomposition with ferric oxide addition was proposed. The mechanism of destruction of sodium cyanide with or without ferric oxide addition under various conditions was examined by XRD, DSC−TG, and chemical analysis technologies. In the absence of ferric oxide, sodium cyanide decomposes at 587.4 °C in air and 879.2 °C in argon atmosphere. In the presence of ferric oxide, about 60% of sodium cyanide decomposes at 350 °C for 30 min in argon, while almost all sodium cyanide decomposes within 30 min in air or O2 with mass ratio of ferric oxide to sodium cyanide of 1:1. The increase of ferric oxide addition, temperature, and heating time facilitates the destruction of sodium cyanide. It is believed that with ferric oxide addition, NaCN reacts with Fe2O3 to form Na4Fe(CN)6, Na2CO3, NaNO2 and Fe3O4 in argon. NaCN decomposes into NaCNO, Na4Fe(CN)6, minor NaNO2, and the formed NaCNO and Na4Fe(CN)6 further decompose into Na2CO3, CO2, N2, FeOx, and minor NOx in air or O2.

The emergence of optical Internet of Things (optical-IoT) for sixth-generation (6G) networks has been envisaged to relieve the bandwidth congestion in the conventional radio frequency (RF) channel, and to support the ever-increasing number of smart devices. Among the plethora of device innovations deemed essential for fortifying the development, herein we report on the visible-to-near-infrared color-conversion luminescent-dyes based on lead sulphide quantum dots (PbS QDs), so as to achieve an eye-safe high-speed optical link. The solution-processed PbS QDs exhibited strong absorption in the visible range, radiative recombination lifetime of 6.4 $\mu$s, as well as high photoluminescence quantum yield of up to 88%. Our proof-of-principle demonstration based on an orthogonal frequency-division multiplexing (OFDM) modulation scheme established an infrared data transmission of 0.27 Mbit/s, readily supporting an indoor optical-IoT system, and shed light on the possibility for PbS-integrated transceivers in supporting remote access control of multiple nodes. We further envisaged that our investigations could find applications in future development of solution-processable PbS-integrated luminescent fibers, concentrators, and waveguides for high-speed optical receivers.

Ultrasound scanning plays an important role in modern clinical examinations. Thanks to its small footprint, low cost, and popularity, it has been widely used in annual physical examinations and many other diagnosis and intervention procedures. However, the scanning results depend heavily on the clinician operators’ skills, causing inconsistency and even false detection. A fully autonomous ultrasound scanning robot can be a promising solution, enabling consistent and accurate operation. In this letter, we propose a procedure-specified imitation learning framework based on clinical protocols to implement autonomous scanning tasks. Based on the targeted carotid artery examination procedure, we design a feature-based visual servo controller for both in-plane and out-of-plane feature tasks. A one-step-exploring (OSE) method is also designed to improve the robustness and transition smoothness in between tasks. The proposed methods are tested and validated with experiments on both medical phantom and human subjects. The results show that the proposed appraoch is able to significantly improve the success rate of procedure completion from 22.2% to 84.6% for the out-of-plane feature-based operation.

Under solvothermal conditions, two new Zn(II)-based coordination polymers, namely {[Zn(tptc)0.5(2,2′-bpy)]·dioxane}n (1, H4tptc = p-terphenyl-2,2″,5″,5‴-tetracarboxylate acid, 2,2′-bpy = 2,2′-bipyridine) and [Zn(tptc)0.5(bib)]n (2, bib = 1,3-bis((imidazol-1-yl) benzene), have been synthesized using the mixed-ligand approach. Furthermore, the luminescence studies show that complex 2 can test acetylacetone selectively and sensitively, and the detection limit is 1.72 ppm. In addition, we evaluated the compounds therapeutic effect against uterine leiomyomas. The uterine leiomyomas rats model was established, the compound 1 and compound 2 was used for treatment. The detection of the transforming growth factor-β (TGF-β) releasing from endometrial stromal cells into plasma was detected with an enzyme linked immunosorbent assay (ELISA) detection kit. Then, the mmp-3 and mmp-7 relative expression levels in the uterine smooth muscle cells after compound treatment were measured by the reverse transcription-polymerase chain reaction (RT-PCR).

In this article, we introduce a new Durrmeyer-type generalization of p , q -Szász-Mirakjan operators using the p , q -gamma function of the second kind. The moments and central moments are obtained. Then, the Voronovskaja-type asymptotic formula is investigated and point-wise estimates of these operators are studied. Also, some local approximation properties of these operators are investigated by means of modulus of continuity and Peetre K -functional. Finally, the rate of convergence and weighted approximation of these operators are presented.

The interest in indole dearomatization, which serves as a useful tool in the total synthesis of related alkaloid natural products, has recently been renewed with the intention of developing new methods efficient in both yield and stereoselective control. Here, we report an enzymatic approach for the oxidative dearomatization of indoles in the asymmetric synthesis of a variety of furoindolines with a vicinal quaternary carbon stereogenic center. This approach depends on the activity of a flavin-dependent monooxygenase, TsrE, which is involved in the biosynthesis of bicyclic thiopeptide antibiotic thiostrepton. TsrE catalyzes 2,3-epoxidation and subsequent epoxide opening in a highly enantioselective manner during the conversion of 2-methyl-indole-3-acetic acid or 2-methyl-tryptophol to furoindoline , with up to > 99% conversion and > 99% ee under mild reaction conditions. Complementing current chemical methods for oxidative indole dearomatization, the TsrE activity-based approach enriches the toolbox in the asymmetric synthesis of products possessing a furoindoline skeleton.

Iodoacetic acid (IAA) is the most genotoxic iodinated disinfection byproduct known in drinking water. Previous studies have shown that IAA may be an endocrine disruptor. However, whether IAA has re...

The frequent occurrence of coal spontaneous combustion (CSC) poses a serious threat to coal mine production safety. Inhibitor fire extinguishing technology has therefore played an important role in reducing CSC in recent years. Microcapsule material is a combined fire extinguishing material that has shown a good effect in preventing CSC. In this study, microcapsule materials were fabricated with short-chain ammonium polyphosphate as the core material and melamine–formaldehyde resin as the capsule material. The microcapsule materials were uniformly mixed with coal samples according to mass ratios of 1:4, 1:5, and 1:6. The quality change of the microcapsule material during heating was detected from thermogravimetric experiments. The results show that microcapsule material decomposition can be divided into five stages. The ammonium polyphosphate begins to decompose at 151.1 °C and the decomposition rate of the microcapsule material reaches a maximum at 200 °C Fourier transform infrared spectroscopy was used to detect the distribution of functional groups during coal oxidation before and after the addition of different microcapsule ratios. The results show that microcapsule materials can reduce the number of hydroxyl and aliphatic hydrocarbons in coal and enhance the stability of aromatic hydrocarbons and oxygenic functional groups. We also performed synchronous thermal analyzer experiments to monitor the temperatures of each characteristic point in the coal oxidation and heating process. The results show that the microcapsule material can reduce the coal mass loss rate, delay the temperature of heat equilibrium by around 100 °C reduce the heat release by more than 4560 J g–1, and increase the maximum temperature of the heat release rate by at least 14 °C. These materials therefore effectively reduce the coal-oxygen composite reaction rate and delay the CSC process.

Swimming pools are commonly treated with chlorine, which reacts with the natural organic matter and organic matter introduced by swimmers and form disinfection byproducts (DBPs) that are associated with respiratory-related issues, including asthma, in avid swimmers. We investigated a complementary disinfectant to chlorine, copper-silver ionization (CSI), with the aim of lowering the amount of chlorine used in pools and limiting health risks from DBPs. We sampled an indoor and outdoor pool treated with CSI-chlorine during the swimming season in 2017-2018 and measured 71 DBPs, speciated total organic halogen, in vitro mammalian cell cytotoxicity, and N-acetyl-l-cysteine (NAC) thiol reactivity as a cytotoxicity predictor. Controlled, simulated swimming pools were also investigated. Emerging DBP concentrations decreased by as much as 80% and cytotoxicity decreased as much as 70% in the indoor pool when a lower chlorine residual (1.0 mg/L) and CSI was used. Some DBPs were quantified for the first time in pools, including chloroacetaldehyde (up to 10.6 μg/L), the most cytotoxic haloacetaldehyde studied to date and a major driver of the measured cytotoxicity in this study. Three highly toxic iodinated haloacetic acids (iodoacetic acid, bromoiodoacetic acid, and chloroiodoacetic acid) were also quantified in pools for the first time. We also found that the NAC thiol reactivity was significantly correlated to cytotoxicity, which could be useful for predicting the cytotoxicity of swimming pool waters in future studies.

Hierarchical 3D nanolayered Zr-2.5Nb has high strength, strain hardening and ductility because of the 3D α/β-Zr networks, which is a promising structural material for nuclear reactor. However, excellent thermal stability is of great importance for materials service in nuclear reactor. Here, we study thermal stability of the hierarchical 3D nanolayered Zr-2.5Nb. After 1 h annealing at various temperatures below 700 °C, α-Zr layer thickness only has a slightly increase. The hardness, yield strength and uniform elongation of the sample remain unchanged. Interface orientation relationship and layer morphology keep stable after annealing, indicating high thermal stability. The duplex phase structures coarsen quickly after annealing at 1000 °C. An obvious increase in hardness and yield strength was observed when sample annealed at 300 °C, which relates to the precipitation of ωiso phase in β-Zr. Controlling the number of ωiso phase is likely a strategy to further enhance the strength and ductility of the alloy.

In this paper, a new and efficient Dual Boundary Element Method (DBEM) named Dual Boundary-Interface Integral Equation Method (DBIIEM) is presented to solve crack problems in objects composed of arbitrary number of different materials. The conventional DBEM has been widely used in crack analysis and proved to be one of the most effective BEM for solving crack problems, however it cannot be directly employed to solve more complicated multi-medium crack problems. The presented DBIIEM can remedy this deficiency by dually collocating the displacement boundary-interface integral equation on one of the multi-medium crack surface and traction boundary-interface integral equation on the other. The newly derived displacement and traction boundary-interface integral equations are naturally fit for solving multi-medium elasticity problems, and independent each other, therefore they can be employed together in multi-medium crack analysis. The established DBIIEM inherits the advantage of single -region formulation of DBEM for solving more complicated crack problems. Complex stress intensity factors which characterize the oscillatory singularity of crack tips located at the interface crack are evaluated. Several numerical examples are given to verify correctness of the presented method.

In this perspective, we outline that a space borne gravitational wave detector network combining LISA and Taiji can be used to measure the Hubble constant with an uncertainty less than 0.5% in ten years, compared with the network of the ground based gravitational wave detectors which can measure the Hubble constant within a 2% uncertainty in the next five years by the standard siren method. Taiji is a Chinese space borne gravitational wave detection mission planned for launch in the early 2030 s. The pilot satellite mission Taiji-1 has been launched in August 2019 to verify the feasibility of Taiji. The results of a few technologies tested on Taiji-1 are presented in this paper. Gravitational wave astronomy has opened the door to test general relativity and the effect of gravity in the Universe. The authors present the capabilities of an overlap between space gravitational wave detectors LISA and Taiji to constrain the Hubble constant to 0.5%, in 10 years, and what can be learned from the satellite pilot Taiji-1 launched in 2019.

In nature, a plant can be infected by multiple viruses simultaneously. However, the effects of coinfection on plant–vector interactions are less well studied. Two begomoviruses of the family Geminiviridae, Tomato yellow leaf curl virus (TYLCV) and Tomato yellow leaf curl China virus (TYLCCNV), occur sympatrically in China. Each of them is reported to increase the performance of whitefly vector via manipulation of plant traits. In this study, we examined the effects of coinfection by the two viruses TYLCV and TYLCCNV on plant–whitefly interactions, compared to that infected by a single virus. We found that plants infected by two viruses showed aggravated symptoms but the performance and preference of whiteflies were not altered significantly compared to singly-infected plants. Coinfection suppressed the transcription of genes involved in jasmonic acid (JA) signaling pathway in plants, but showed no significant difference to single-virus infected plants. These findings suggest that although TYLCV and TYLCCNV may synergistically induce plant symptoms, they did not manipulate synergistically plant-mediated responses to the insect vector.

Abscisic acid (ABA) induces chlorophyll degradation and leaf senescence; however, the molecular mechanism remains poorly understood, especially in woody plants. In this study, we found that MdABI5 plays an essential role in the regulation of ABA-triggered leaf senescence in Malus domestica (apple). Through yeast screening, three transcription factors, MdBBX22, MdWRKY40 and MdbZIP44, were found to interact directly with MdABI5 in vitro and in vivo. Physiological and biochemical assays showed that MdBBX22 delayed leaf senescence in two pathways. First, MdBBX22 interacted with MdABI5 to inhibit the transcriptional activity of MdABI5 on the chlorophyll catabolic genes MdNYE1 and MdNYC1, thus negatively regulating chlorophyll degradation and leaf senescence. Second, MdBBX22 interacted with MdHY5 to interfere with the transcriptional activation of MdHY5 on MdABI5, thereby inhibiting the expression of MdABI5, which also contributed to the delay of leaf senescence. MdWRKY40 and MdbZIP44 were identified as positive regulators of leaf senescence. They accelerated MdABI5-promoted leaf senescence through the same regulatory pathways, i.e., interacting with MdABI5 to enhance the transcriptional activity of MdABI5 on MdNYE1 and MdNYC1. Taken together, our results suggest that MdABI5 works with its positive or negative interaction partners to regulate ABA-mediated leaf senescence in apple, in which it acts as a core regulator. The antagonistic regulation pathways ensure that plants respond to external stresses flexibly and efficiently. Our results provide a concept for further study on the regulation mechanisms of leaf senescence.

In this study, sodium alginate (SA) was used as a carbon precursor and K2CO3 as an activator to prepare SA-based porous carbon (SAC) with high specific surface area in one step. The optimal product...

A wavelength sensor as a representative optoelectronic device plays an important role in many fields including visible light communication, medical diagnosis, and image recognition. In this study, a wavelength-sensitive detector with a new operation mechanism was reported. The as-proposed wavelength sensor which is composed of two parallel PtSe2/thin Si Schottky junction photodetectors is capable of distinguishing wavelength in the range from ultraviolet to near infrared (UV-NIR) light (265 to 1050 nm), in that the relationship between the photocurrent ratio of both photodetectors and incident wavelength can be numerically described by a monotonic function. The unique operation mechanism of the thin Si based wavelength sensor was unveiled by theoretical simulation based on Synopsys Sentaurus Technology Computer Aided Design (TCAD). Remarkably, the wavelength sensor has an average absolute error of ±4.05 nm and an average relative error less than ±0.56%, which are much better than previously reported devices. What is more, extensive analysis was performed to reveal how and to what extent the working temperature and incident light intensity, and the thickness of the PtSe2 layer will influence the performance of the wavelength sensor.

The imprinted polymers were prepared to absorb dichlorophen (DCP) by using mesoporous silica with ordered pores and high specific surface area. Both scanning electron microscopy and transmission electron microscopy results suggested that the mesoporous silica nanosphere pores had a periodic distribution. The imprinted layer of polymers was thin and uniform. The adsorption experiments showed that the adsorption of imprinted polymers was obviously improved due to the presence of mesoporous structure. The maximum adsorption capacity of MSNs@MIPs at 318 K was 91.1 mg/g, and the adsorption process rapidly reached the equilibrium within 40 min. The adsorption isotherm was well fitted by the Freundlich isotherm model, indicating that multimolecular layer adsorption mechanism governs the adsorption of DCP by the polymers. The adsorption of MSNs@MIPs complied with pseudo-second-order kinetic model. Both selective and regenerative experiments demonstrated that MSNs@MIPs can be successfully applied for selective adsorption of DCP.

IASCC of stainless steel has been the most important issue for internals BFBs. The inspection data analysis indicates that there is a closed relation between irradiation fluence and cracked BFBs distribution. Then the nanoindentation and 3DAP tests were carried out to study the hardening and radiation induced segregation (RIS) behaviors of the reactor internals stainless steel specimens irradiated with 6 MeV Xe ions at room temperature. It is indicated that higher irradiation damage will cause more significant hardening and RIS and consequently increase the IASCC susceptibility.

Clinically, the primary cause of chemotherapy failure belongs to the occurrence of cancer multidrug resistance (MDR), which directly leads to the recurrence and metastasis of cancer along with high mortality. More and more attention has been paid to multifunctional nanoplatform-based dual-therapeutic combination to eliminate resistant cancers. In addition to helping both cargoes improve hydrophobicity and pharmacokinetic properties, increase bioavailability, release on demand and enhance therapeutic efficacy with low toxic effects, these smart co-delivery nanocarriers can even overcome drug resistance. Here, this review will not only present different types of co-delivery nanocarriers, but also summarize targeted and stimuli-responsive combination nanomedicines. Furthermore, we will focus on the recent progress in the co-delivery of dual-drug using such intelligent nanocarriers for surmounting cancer MDR. Whereas it remains to be seriously considered that there are some knotty issues in the fight against MDR of cancers via using co-delivery nanoplatforms, including limited intratumoral retention, the possible changes of combinatorial ratio under complex biological environments, drug release sequence from the nanocarriers, and subsequent free-drug resistance after detachment from the nanocarriers. It is hoped that, with the advantage of continuously developing nanomaterials, two personalized therapeutic agents in combination can be better exploited to achieve the goal of cooperatively combating cancer MDR, thus advancing the time to clinical transformation.

An all-solid organic semiconducting conjugated polymer poly(2-methoxy-5-(2ʹ-ethyl-hexyloxy)-p-phenylenevinylene) (MEH-PPV) activated polarisation grating (PG) laser was demonstrated for the first t...

As a common pretreatment process for coal chemical wastewater, the conventional one-stage coagulation process has the problem of poor removal of small size oil, which will inhibit the subsequent biological treatment. Measures to improve oil removal efficiency based on the development of new coagulants and the addition of composite processes are common in the literature, but two-stage coagulation to improve coagulation efficiency has not been reported to date. Here, we optimized coagulation parameters and compared the oil removal efficiency of two-stage coagulation and one-stage coagulation. Under the same total dosage of coagulant (PAC), the optimum removal of oil in two-stage coagulation was achieved 90% which increased by 11% compared to one-stage process. P10 and P 1 μm were proposed to evaluate the oil removing effect of two-stage coagulation. In addition, SEM scanning was used to conduct flocs analysis and two-stage coagulation process simulation, revealing the principle of the excellent oil removal performance of two-stage coagulation. Finally, coagulant in filter residue was recovered by acidification method and the recovered coagulant was used again in the two-stage coagulation process of coal chemical wastewater. These results suggest that two-stage coagulation is a cost-effective alternative oil removal technique with high energy efficiency and environmental benign. This research may offer helpful insights to develop an advanced oil removal process.

In this paper, a meshless BEM based on the radial integration method is developed to solve transient non-homogeneous convection-diffusion problem with spatially variable velocity and time-dependent source term. The Green function served as the fundamental solution is adopted to derive the boundary domain integral equation about the normalized field quantity. The two-point backward finite difference technique is utilized to discretize the time-dependent terms in the integral equation, which results in that the final integral equation formulation is only related with the normalized field quantity at the current time and has three domain integrals. Both two domain integrals regarding the normalized field quantity at the current and previous times are transformed into boundary integrals by using radial integration method and radial basis function approximation. For domain integral about the source term being known function of time and coordinate, radial basis functions approximation is still adopted to make the transformed boundary integral be evaluated only once, not at each time level. A pure boundary element algorithm with boundary-only discretization and internal points is established and the system of equations is assembled like the corresponding steady problem. Four numerical examples are given to demonstrate the accuracy and effectiveness of the present method.

Platinum telluride (PtTe2) has garnered significant research enthusiasm owing to its unique characteristics. However, large-scale synthesis of PtTe2 toward potential photoelectric and photovoltaic application has not been explored yet. Herein, we report direct tellurization of Pt nanofilms to synthesize large-area PtTe2 films and the influence of growth conditions on the morphology of PtTe2. Electrical analysis reveals that the as-grown PtTe2 films exhibit typical semimetallic behavior, which is in agreement with the results of first-principles density functional theory (DFT) simulation. Moreover, the combination of multilayered PtTe2 and Si results in the formation of a PtTe2/Si heterojunction, exhibiting an obvious rectifying effect. Moreover, the PtTe2-based photodetector displays a broadband photoresponse to incident radiation in the range of 200-1650 nm, with the maximum photoresponse at a wavelength of ∼980 nm. The R and D* of the PtTe2-based photodetector are found to be 0.406 A W-1 and 3.62 × 1012 Jones, respectively. In addition, the external quantum efficiency is as high as 32.1%. On the other hand, the response time of τrise and τfall is estimated to be 7.51 and 36.7 μs, respectively. Finally, an image sensor composed of a 8 × 8 PtTe2-based photodetector array was fabricated, which can record five near-infrared (NIR) images under 980 nm with a satisfying resolution. The result demonstrates that the as-prepared PtTe2 material will be useful for application in NIR optoelectronics.

Nanomedicines (NMs) have played an increasing role in cancer therapy as carriers to efficiently deliver therapeutics into tumor cells. For this application, the uptake of NMs by tumor cells is usually a prerequisite to deliver the cargo to intracellular locations, which mainly relies on endocytosis. NMs can enter cells through a variety of endocytosis pathways. Different endocytosis pathways exhibit different intracellular trafficking routes and diverse subcellular localizations. Therefore, a comprehensive understanding of endocytosis mechanisms is necessary for increasing cellular entry efficiency and to trace the fate of NMs after internalization. This review focuses on endocytosis pathways of NMs in tumor cells, mainly including clathrin- and caveolae-mediated endocytosis pathways, involving effector molecules, expression difference of those molecules between normal and tumor cells, as well as the intracellular trafficking route of corresponding endocytosis vesicles. Then, the latest strategies for NMs to actively employ endocytosis are described, including improving tumor cellular uptake of NMs by receptor-mediated endocytosis, transporter-mediated endocytosis and enabling drug activity by changing intracellular routes. Finally, active targeting strategies towards intracellular organelles are also mentioned. This review will be helpful not only in explicating endocytosis and the trafficking process of NMs and elucidating anti-tumor mechanisms inside the cell but also in rendering new ideas for the design of highly efficacious and cancer-targeted NMs.

Enhanced hole injection is essential to achieve high performance in perovskite light-emitting diodes (LEDs). Here, a strategy is introduced to enhance hole injection by an electric dipole layer. Hopping theory demonstrates electric dipoles between hole injection layer and hole transport layer can enhance hole injection significantly. MoO3 is then chosen as the electric dipole layer between PEDOT:PSS (hole injection layer) and PVK (hole transport layer) to generate electric dipoles due to its deep conduction band level. Theoretical results demonstrate that strong electric fields are produced for efficient hole injection, and recombination rate is substantially increased. Capacitance-voltage analyses further prove efficient hole injection by introducing the electric dipole layer. Based on the proposed electric dipole layer structure, perovskite LEDs achieve a high current efficiency of 72.7 cd A−1, indicating that electric dipole layers are a feasible approach to enhance perovskite LEDs performance. Perovskite nanocrystals are promising for use in light emitting diodes, but improved hole injection is needed. Here, MoO3 is added as an electric dipole layer between hole injection and transport layers, achieving a current efficiency of 72.7cd/A in a green light emitting diode.

We herein report the manipulation of the crystallographic packing modes of Pt1Ag28(S-Adm)18(PPh3)4 nanoclusters by altering counterions as different polyoxometalates (POMs). Specifically, the Cl- anion of the presynthesized Pt1Ag28 nanocluster was substituted by POM anions including [Mo6O19]2-, [W6O19]2-, or [PW12O40]3-. The crystal lattices of these Pt1Ag28 nanoclusters with diverse anions showed distinct packing modes and thus manifested remarkably distinguishable crystalline-state optical properties and nitrogen adsorption-desorption performances. Overall, the combination of intercluster control in this work and intracluster control reported previously (the control over metal-ligand within the nanocluster framework) accomplished a more comprehensive manipulation over the M29(SR)18(PR'3)4 nanocluster system, which enables us to further grasp the structure-property correlations at the atomic level.

A tunable frequency-multiplying optoelectronic oscillator (OEO) based on a dual-parallel Mach-Zehnder modulator (DPMZM) is proposed and experimentally demonstrated. In the proposed system, the tunable fundamental microware signal is generated by a tunable optoelectronic oscillator incorporating a phase-shifted fiber Bragg grating (PS-FBG). By adjusting the DC bias of the DPMZM, the frequency-doubled microwave signal with a tunable frequency range from 11 GHz to 20 GHz and the frequency-quadrupled microwave signal with a tunable frequency range from 22.5 GHz to 26 GHz are generated. The phase noises of the fundamental, frequency-doubled and frequency-quadrupled signals at 10 kHz offset frequency are −105.9 dBc/Hz, −103.3 dBc/Hz and −86.2 dBc/Hz, respectively.

Calcium (Ca) and silicon (Si) have been found to reduce inorganic pollutant accumulation by agricultural plants. Arsenic (As) and cadmium (Cd) are the most common and dangerous inorganic pollutants in cultivated soil that often present simultaneously. Due to difference in chemical properties of As and Cd, concurrent minimizing their uptake poses a problem. The effect of two types of Si fertilizers and Si-treated metallurgical slag applied with or without limestone or gypsum on the As and Cd accumulation by rice was investigated in medium-polluted paddy soils in field test. Application of Ca- and Si-rich substances reduced the grain As by 16 to 68% and the grain Cd by 30 to 56% with increasing yield by 16.6 to 31.0%. The root-to-grain transport of As and Cd depended on the plant-available Si supply in the soil. Soil-applied Si resulted in diminished As and Cd translocation inside plant tissue and decreased the pollutant mobility in the soil. The combination of Ca- and Si-rich substances reinforced the reduction in both the pollutant mobility in soil and accumulation by rice grain. Silicon-rich materials mainly impacted both As and Cd translocation into the grain, whereas Ca-rich substances demonstrated a more remarkable effect on the pollutant mobility in the soil. Limestone showed a higher decrease in the mobility of Cd, while gypsum was more efficient in the case of As. Thus, for minimizing pollutant accumulation by rice grain, the combination of Si fertilizer with limestone or gypsum could be recommended in the co-contaminated soil with prevailing Cd or As, respectively.

By using field survey, sampling, and indoor analysis, we analyzed the geochemical characteristics of heavy metals in the blueberries and soil of the core blueberry production area of Majiang in Guizhou, China. Analyses were based on national standards for soil pollution risk control on agricultural land (GB15618-2018) and pollution index limits in food (GB2762-2017/2012). The results demonstrated that heavy metal content in the soil profile of this area exceeds standards, but standards were exceeded mainly in the lower layer of the profile, and blueberry growth was not substantially affected. Except for in Lanmenggu, heavy metals in the cultivation soil layer of Majiang Blueberry Farms did not considerably exceed standards. The content of heavy metals in blueberry did not exceed the standard, so it was a safe fruit. These results can provide a reference for the safe cultivation of Majiang blueberries.

Aprotic Li-O2 batteries with high theoretical energy density are regarded as promising next-generation energy storage devices. However, the accumulation of discharge products (Li2O2) duiring the discharge/charge processes would lead to high overpotential, low round-trip efficiency and poor cycling stability of the batteries. Soluble redox mediators (RMs) have been proved to be efficient in promoting the oxidation of Li2O2 particles. However, the self-discharge of the electrochemically oxidized RMs (RMsox) on the surface of Li metal would accelerate the formation of lithium dendrites. In this work, nitrogenous radicals, 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH), is designed and employed as a RMs to lower the overpotential of Li–O2 batteries. Moreover, the self-discharge of the oxidized DPPH on the surface of Li metal and the formation of lithium dendrites are successfully suppressed by the formation of graphene/luteolin protective layer on Li metal. Consequently, an ultrastable cycle stability (>150 cycles) is achieved with DPPH and the stable graphene/luteolin protective layer for the Li metal anodes. These synergistic effect of RMs and stable Li protective layer may inspire the development of sustainable and durable Li–O2 batteries.

Shock wave is emitted into the plate and sphere when a sphere hypervelocity impacts onto a thin plate. The fragmentation and phase change of the material caused by the propagation and unloading of shock wave could result in the formation of debris cloud eventually. Propagation models are deduced based on one-dimensional shock wave theory and the geometry of sphere, which uses elliptic equations (corresponding to ellipsoid equations in physical space) to describe the propagation of shock wave and the rarefaction wave. The “Effective thickness” is defined as the critical plate thickness that ensures the rarefaction wave overtake the shock wave at the back of the sphere. The “Effective thickness” is directly related to the form of the debris cloud. The relation of the “Effective thickness” and the “Optimum thickness” is also discussed. The impacts of Al spheres onto Al plates are simulated within SPH to verify the propagation models and associated theories. The results show that the wave fronts predicted by the propagation models are closer to the simulation result at higher impact velocity. The curvatures of the wave fronts decrease with the increase of impact velocities. The predicted “Effective thickness” is consistent with the simulation results. The analysis about the shock wave propagation and unloading in this paper can provide a new sight and inspiration for the quantitative study of hypervelocity impact and space debris protection.

The correlation between sludge reduction induced by 2,4,6-trichlorophenol (2,4,6-TCP) as an uncoupler and sludge toxicity was investigated in sequence batch reactors over a 100-d operation period. The influent concentrations of 2,4,6-TCP tested were 10 mg/L, 30 mg/L, and 50 mg/L. Sludge reduction, chemical oxygen demand (COD) removal rate, and sludge toxicity were measured. The results showed that from 30 to 80 d, when the COD removal rate was at an acceptable level, the sludge reduction levels for the 10 mg/L, 30 mg/L, and 50 mg/L groups were 9.7%, 31.6%, and 41.5%, respectively, and the average sludge toxicity values were 24.2%, 38.0%, and 53.0%, respectively. Sludge reduction was positively correlated with sludge toxicity. The two-dimensional polyacrylamide gel electrophoresis/results showed that extracellular and intracellular proteins secreted by the activated sludge during uncoupling metabolism were positively correlated with sludge toxicity. Taking the COD removal rate, sludge reduction, and sludge toxicity into consideration, the optimal influent concentration of the uncoupler 2,4,6-TCP was 30 mg/L when the initial mixed liquid suspended solids of sludge was 2,500 mg/L.

For PbS quantum dot (QD)-based optoelectronic devices, gold is the most frequently used electrode material. In most device architectures, gold is in direct contact with the QD solid. To better understand the formation of the interface between gold and a close-packed QD layer at an early stage, in situ grazing-incidence small-angle X-ray scattering is used to observe the gold sputter deposition on a 1,2-ethanedithiol (EDT)-treated PbS QD solid. In the kinetics of gold layer growth, the forming and merging of small gold clusters (radius less than 1.6 nm) are observed at the early stages. The thereby formed medium gold clusters (radius between 1.9-2.4 nm) are influenced by the QDs' templating effect. Furthermore, simulations suggest that the medium gold clusters grow preferably along the QDs' boundaries rather than as a top coating of the QDs. When the thickness of the sputtered gold layer reaches 6.25 nm, larger gold clusters with a radius of 5.3 nm form. Simultaneously, a percolation layer with a thickness of 2.5 nm is established underneath the gold clusters. This fundamental understanding of the QD-gold interface formation will help to control the implementation of sputtered gold electrodes on close-packed QD solids in device manufacturing processes.

Wind speed and wind direction are two important factors to describe the wind properties. The statistical probability model of wind speed and wind direction is widely used to characterize the uncertainty of wind field around the structures. Considering the correlation between the wind speed and wind direction, they should be modeled simultaneously, which highlights the importance of using joint probability density function (JPDF) to describe the wind properties. An angular–linear (AL) model is employed to construct the JPDF of wind speed and wind direction based on long-term monitoring data. The finite mixture (FM) Gumbel distribution, which models the wind speed, and the FM von Mises distribution, which models the wind direction, are proposed to formulate the AL model. Expectation–maximization (EM) and genetic algorithm (GA) are adopted to estimate the AL model parameters. For the EM method, the analytical expressions for calculating the AL model parameters are derived. For the GA method, the analytical fitness functions are derived. These derived analytical expressions facilitate the implementation of the EM and GA methods. One-year wind monitoring data collected by structural health monitoring (SHM) system installed on Jiubao Bridge is employed to demonstrate the feasibility of the AL model-based method in evaluating the wind properties. The results show that the AL model formulated by the FM Gumbel distribution and FM Von Mises distribution is effective for establishing JPDF for joint modeling of the wind speed and wind direction. In the AL model, the EM method is more effective for estimating the parameters of the FM von Mises distribution, whereas the GA methods is more powerful for estimating the parameters of the FM Gumbel distribution.

At present, inhibitors have been widely used in the field of coal fire prevention and control, but there are some defects in the use of them. So it is necessary to find a new practical and economical inhibitor. Dissolvable tiny-foam extinguisher (DTE) is environment-friendly, high in thermal stability, and fast in cooling. In view of the good performance of the product, the thermal behavior effects of DTE on coal spontaneous combustion were investigated through experimental tests. A scanning electron microscopy was used to study changes in the surface microstructure of raw coal after DTE treatment. Laser thermal conductivity analysis and simultaneous thermal analysis were used to test the effects of DTE at mass fraction of 0%, 5%, 10%, and 15% on the thermophysical properties, mass loss, characteristic temperature, and heat release of coal during heating. The surface of the DTE-treated coal sample was covered in a dense film. The treated coal sample had lower thermal diffusivity and thermal conductivity values and a higher specific heat capacity. Moreover, coal treated with DTE showed no obvious oxygen absorption or mass gain during initial heating, and the dry cracking temperature was greatly increased by 37 °C, 53 °C, and 100 °C, respectively. The initial heat release temperature increased by more than 170 °C, and the amount of the initial heat absorption was more than 52.2 times that of untreated samples. Oxidation kinetics were applied to calculate the activation energy of the coal during thermal decomposition and ignition, and the activation energies of the treated samples at the thermal decomposition and combustion stages increased by 161%, 179%, and 173%, respectively. From these results, we concluded that DTE could inhibit heat accumulation by blocking oxygen contact with the coal and greatly reducing heat release during heating. Besides, only a small quantity of DTE was needed to effectively inhibit coal self-ignition. These results provide reference for the field application of DTE in restraining coal spontaneous combustion.

In addition to using common ligands (phosphine, thiol, or acetylene ligands) to protect metal nanoclusters, halogens can also be used to participate in the formation of nanoclusters. In this study, we reported the formation of two new nanoclusters promoted by chlorides released from HAuCl4: one [Au1Ag26(SR)18Cl] with an icosahedral Au1Ag12 kernel, which is surrounded by the shell of Ag14(SR)18, and the special chlorine atom fills the space between the metal core and the metal shell; the other [Au6Ag33(Dppf)2(SR)16Cl6]+ with the kernel consisted of two icosahedral Au3Ag10 units by sharing one vertex Ag atom, which is protected by the complicated shell of Ag14(Dppf)2(SR)16Cl4, two special chlorine atoms also fill the space between the metal core and the metal shell. Thus, both two nanoclusters suggest that the chlorine atoms can exist in the space between the metal kernel and out shell, playing a critical role in maintaining the stability of the overall structures. These will deepen the comprehensive understanding of chlorine in constructing the structures of alloy nanoclusters and will also be helpful in mapping out the new strategies for core-shell nanocluster synthesis.

Lead-free double perovskite phosphors are promising alternatives to lead halide perovskites for wide uses in optoelectronic applications, but suffer from a low quantum efficiency. Here, we propose ...

Fluorescence spectra and lifetimes of single molecules reflect their specific local environments involved, which is not available from the ensemble-averaged measurements. Usually, low signal to noi...