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The rapid expansion of urbanization both in scale and population leads to a series of serious urban diseases, which become a huge obstacle to the healthy and sustainable development of cities. To alleviate these problems and challenges, China launched a smart city construction program in the past decade and has taken the lead in smart city construction in the world. However, there is still a lack of reflection and summary on the practice of smart cities in China. Based on the definition and concept of smart city, this paper points out the internal and external driving factors of China’s smart city development, then summarizes the four major characteristics of China’s smart city construction practice, and explores the main problems existing in the process of China’s smart city construction. Through the reflection and summary, we can facilitate development of smart cities in China, provide useful reference to urban planners and smart city practitioners in other countries and regions, and promote the healthy and sustainable development of cities.

Covalent organic frameworks (COFs) have emerged as an extremely promising material for photocatalytic water splitting for hydrogen production. However, their photocatalytic performance is seriously affected by the properties of their donors, acceptors and linkages. So far, few studies have been reported on the key roles of the linkages of a specific COF in improving its photocatalytic hydrogen production performance. Herein, this study designed and synthesized two thiadiazole-based COFs linked by imine and alkyne bonds. The results show that the photocatalytic hydrogen production performance of imine-linked COFs (TeTz-COF1) is 19.6 times higher than that of alkyne-linked COFs (TeTz-COF2). Impressively, TeTz-COF1 achieves an apparent quantum efficiency of 3.5% at 475 nm due to the presence of imine bonds. The experimental results confirm that TeTz-COF1 with imine linkages shows higher photocurrent density, lower photocurrent resistance, and longer fluorescence lifetime than TeTz-COF2 with alkyne linkages. Meanwhile, the well-defined density functional theory (DFT) calculations further suggest that both the imine bond and the acetylene bond belong to the HOMO orbitals. Particularly, the imine bonds endow TeTz-COF1 with more delocalized orbital occupation and smaller work functions, thus leading to its lower excited state energy, stronger carrier separation ability and faster electron migration capability. Both theoretical analysis and the experimental results prove that the presence of imine bonds in TeTz-COF1 can enable the efficient separation and fast transport of photogenerated carriers and high reducing ability of photogenerated electrons. This work may provide important guiding significance for the development of new COFs in the direction of photocatalytic water splitting for hydrogen production.

Adventitious root (AR) formation is critical for the efficient propagation of elite horticultural and forestry crops. Despite decades of research, the cellular processes and molecular mechanisms underlying AR induction in woody plants remain obscure. We examined the details of AR formation in apple (Malus domestica) M.9 rootstock, the most widely used dwarf rootstock for intensive production, and investigated the role of polar auxin transport in postembryonic organogenesis. AR formation begins with a series of founder cell divisions and elongation of the interfascicular cambium adjacent to vascular tissues. This process is associated with a relatively high indole acetic acid (IAA) content and hydrolysis of starch grains. Exogenous auxin treatment promoted this cell division, as well as the proliferation and reorganization of the endoplasmic reticulum and Golgi membrane. In contrast, treatment with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) inhibited cell division in the basal region of the cuttings and resulted in abnormal cell divisions during the early stage of AR formation. In addition, PIN-FORMED (PIN) transcripts were differentially expressed throughout the whole AR development process. We also detected upregulation of MdPIN8 and MdPIN10 during induction; upregulation of MdPIN4, MdPIN5, and MdPIN8 during extension; and upregulation of all MdPINs during AR initiation. This research provides an improved understanding of the cellular and molecular underpinnings of the AR process in woody plants.

Porcine epidemic diarrhea virus (PEDV) is a highly contagious pathogenic virus that causes severe diarrhea and dehydration in pigs of all ages. Deoxynivalenol (DON), the most abundant trichothecene in food and feed, causes vomit and diarrhea in animals and human. However, whether DON exposure could affect PEDV infection remains unknown. Herein, we investigated the impacts of DON on entry and replication of PEDV, morbidity situation of piglets and the mechanisms involved. In vivo, twenty-seven piglets infected naturally with PEDV were randomly divided into three groups, receiving the basal diet containing 0, 750 and 1500 μg/kg DON, respectively. We observed significant increases in the diarrhea rates, the villous injury of jejunums and the PEDV proliferation of duodenum, jejunum, ileum and mesenterium of piglets in experimental groups compared with control. Additionally, the autophagosome-like vesicles and the autophagy-related protein expressions were also increased in experimental groups. In vitro, we observed that, approximately 2 hrs post-infection, 0.1, 0.5 and 1.0 μM DON promoted PEDV entry (P < 0.05) in IPEC-J2s and resulted in tight junction protein occludin internalization. Knockdown of occludin and CRISPR-Cas9-mediated knockout of LC3B indicated a vital role of autophagy-induced occludin internalization in DON-promoted PEDV entry. We also observed that, 24 hrs post-infection, a significant increase in PEDV replication after 0.1, 0.5 and 1.0 μM DON treatment, along with the induction of a complete autophagy. Specifically, deletion of LC3B indicated a crucial role of autophagy in DON-promoted PEDV replication. Pretreatment with SB202190, a p38 signaling inhibitor, abolished the induction of autophagy. Furthermore, downregulation of type I interferon revealed that DON contributed PEDV to escape innate immune. Mechanistically, DON-caused innate immune escape was related to the upregulation of LC3B, which further inhibited STING phosphorylation. Taken together, DON could promote PEDV infection by inducing occludin internalization and innate immune escape via triggering p38-mediated autophagy.Author summaryPorcine epidemic diarrhea (PED), a devastating enteric disease, leads to catastrophic economic loss to the global pig industry. Its primary pathogen is the coronavirus PED virus (PEDV). Growing evidence indicates that pathogen infection is not the only factor of PED outbreaks, other non-infectious factors is also related to this disease. We guessed some ubiquitous substances, such as deoxynivalenol (DON), that lead to pig intestinal epithelial cell stress might encourage the progress and spread of PED. In the present study, the weaning piglets infected naturally with PEDV and the IPEC-J2 cell line were selected as models to explore the effects of DON on PEDV infection, morbidity and gut barrier. Our results showed that DON exposure can promote PEDV infection in vitro and in vivo, and the underlying mechanism might be related to LC3B-mediated autophagy. Our findings reveal new pathways for developing potential novel antiviral strategies against PEDV infection.

The ABA/water stress/ripening-induced (ASR) gene family exists universally in higher plants, and many ASR genes are up-regulated during periods of environmental stress and fruit ripening. Although a considerable amount of research has been performed investigating ASR gene response to abiotic stresses, relatively little is known about their roles in response to biotic stresses. In this report, we identified five ASR genes in apple (Malus × domestica) and explored their phylogenetic relationship, duplication events, and selective pressure. Five apple ASR genes (Md-ASR) were divided into two clades based on phylogenetic analysis. Species-specific duplication was detected in M. domestica ASR genes. Leaves of ‘Golden delicious’ and ‘Starking’ were infected with Alternaria alternata f. sp. mali, which causes apple blotch disease, and examined for the expression of the ASR genes in lesion areas during the first 72 h after inoculation. Md-ASR genes showed different expression patterns at different sampling times in ‘Golden delicious’ and ‘Starking’. The activities of stress-related enzymes, peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia lyase (PAL), and polyphenoloxidase (PPO), and the content of malondialdehyde (MDA) were also measured in different stages of disease development in two cultivars. The ASR gene expression patterns and theses physiological indexes for disease resistance suggested that Md-ASR genes are involved in biotic stress responses in apple.

The biodegradation of Aflatoxin B1 (AFB1) is an industry of increasing importance. Bacillus licheniformis BL-010 was isolated from the aflatoxin contaminated corn feed storage, and was shown to degrade AFB1 efficiently. Here we present the complete genome sequence of BL-010, the genome comprises 4,287,714 bp in a circular chromosome with a GC content of 46.12% and contains genes encoding AFB1 degrading enzymes. The genome sequence displayed that this strain contains genes involved in production of laccase, aromatic ring-opening dioxygenase which could detoxify AFB1. Complete genome sequence of the strain BL-010 can further provide the genomic basis for the biotechnological application of strain BL-010 as an effective way to degrade AFB1.

For the first time, a simple and highly sensitive electrochemical dimetridazole (DMZ) sensor based on a carbon paste electrode modified with core-shell aluminum doped surface molecularly imprinted siloxane has been developed and tested. Because of aluminum doping, the surface imprinting sensor exhibits higher rebinding capacity, recognition ability and affinity for DMZ in comparison with the aluminum free and the non-imprinted ones. In addition, the as-prepared sensor shows good stability and satisfactory reproducibility for the determination of DMZ. Under optimal experimental conditions, the peak currents by differential pulse stripping voltammetry were found to vary linearly with DMZ concentrations in the range from 1.0 × 10 −8 to 1.0 × 10 −6 mol L −1 and 1.0 × 10 −6 to 1.0 × 10 −4 mol L −1 , with a detection limit of 3.6 × 10 −9 mol L −1 . This sensor was successfully employed to detect DMZ in egg, milk powder, and pig feed samples with acceptable recoveries of 91.4% to 107.6%, which was verified by high performance liquid chromatography.

Alternaria blotch, caused by Alternaria alternata f. sp. mali, is a destructive defoliating disease that affects apple worldwide, especially in Asia. Despite previous efforts in characterizing this disease, few have reported on nucleotide binding sites (NBS)-encoding genes in response to pathogen infection. In this study, we characterized the morphological and gene expression response of ‘Golden Delicious’ and ‘Starking’ apples challenged by A. alternata. Inoculation of detached leaves of ‘Golden Delicious’ resulted in a rapid initiation of disease symptoms but a slow spread of the infection from the point of inoculation. In contrast, detached leaves of ‘Starking’ exhibited a delayed visibility of infection but a rapid spread of the infection once it was established. Based upon quantitative reverse transcription polymerase chain reaction data, we characterized the expression of 12 NBS-encoding genes in response to infection by A. alternata. We further characterized the structure, chromosomal location, and...

Two novel methods, first derivative spectrophotometric method ((1)D) and first derivative ratio spectrophotometric method ((1)DR), have been developed for the simultaneous trace determination of rhodamine B (RhB) and rhodamine 6G (Rh6G) in food samples after dispersive liquid-liquid microextraction (DLLME). The combination of derivative spectrophotometric techniques and DLLME procedure endows the presented methods with enhanced sensitivity and selectivity. Under optimum conditions, the linear calibration curves ranged from 5 to 450 ng mL(-1), with the correlation coefficients (r) of 0.9997 for RhB and 0.9977 for Rh6G by (1)D method, and 0.9987 for RhB and 0.9958 for Rh6G by (1)DR method, respectively. The calculated limits of detection (LODs) based on the variability of the blank solutions (S/N = 3 criterion) for 11 measurements were in the range of 0.48-1.93 ng mL(-1). The recoveries ranged from 88.1% to 111.6% (with RSD less than 4.4%) and 91.5-110.5% (with RSD less than 4.7%) for (1)D and (1)DR method, respectively. The influence of interfering substances such as foreign ions and food colorants which might be present in the food samples on the signals of RhB and Rh6G was examined. The developed methods have been successfully applied to the determination of RhB and Rh6G in black tea, red wine and chilli powder samples with the characteristics of simplicity, cost-effectiveness, environmental friendliness, and could be valuable for routine analysis.

A sensitive and selective electrochemical sensor for metronidazole (MNZ) was developed. The core–shell metronidazole-magnetic molecularly imprinted polymer (MMIP) was synthesized and then attached to the surface of magnetic glassy carbon electrode (MGCE) with the help of magnetic force in order to prepare MMIP/MGCE sensor. The performance of the obtained imprinted sensor was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Various factors, known to affect the response behavior of the MMIP/MGCE electrode, were studied and optimized. The imprinted sensor exhibits high recognition ability and affinity for MNZ in comparison with the nonimprinted one. In addition, the MMIP/MGCE also shows good stability and acceptable reproducibility for the determination of MNZ. Under the optimal experimental conditions, the current response of the electrochemical sensor was linear to MNZ concentrations in the range from 5.0 × 10−8 to 1.0 × 10−6 M, with the detection limit of 1.6 × 10−8 M. The method was successfully applied to the analysis of MNZ in milk samples and honey samples with acceptable recoveries of 93.5–102.2%.

We have prepared a nanoparticle-based metronidazole-imprinted polymer by combining a surface molecular imprinting technique with a sol–gel process. Metronidazole was used as a template, 3-aminoprophyltriethoxysilane as the functional monomer, and tetraethyl orthosilicate as the cross-linker. The resulting magnetic molecularly imprinted polymer was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy. The adsorbent can be applied to the solid phase extraction of metronidazole and exhibits high adsorption capacity, good selectivity, favorable reusability and the feature of magnetic separation. The binding performances of the adsorbent were evaluated by equilibrium rebinding experiments and Scatchard analysis. The material was successfully applied to solid phase extraction of metronidazole, followed by spectrophotometric determination in food samples. Spiked recoveries ranged from 88.5% to 97.0%, with relative standard deviation (RSD) of

The disease resistance (R) genes play an important role in protecting plants from infection by diverse pathogens in the environment. The nucleotide-binding site (NBS)-leucine-rich repeat (LRR) class of genes is one of the largest R gene families. Chinese chestnut (Castanea mollissima) is resistant to Chestnut Blight Disease, but relatively little is known about the resistance mechanism. We identified 519 NBS-encoding genes, including 374 NBS-LRR genes and 145 NBS-only genes. The majority of Ka/Ks were less than 1, suggesting the purifying selection operated during the evolutionary history of NBS-encoding genes. A minority (4/34) of Ka/Ks in non-TIR gene families were greater than 1, showing that some genes were under positive selection pressure. Furthermore, Ks peaked at a range of 0.4 to 0.5, indicating that ancient duplications arose during the evolution. The relationship between Ka/Ks and Ks indicated greater selective pressure on the newer and older genes with the critical value of Ks = 0.4–0.5. Notably, species-specific duplications were detected in NBS-encoding genes. In addition, the group of RPW8-NBS-encoding genes clustered together as an independent clade located at a relatively basal position in the phylogenetic tree. Many cis-acting elements related to plant defense responses were detected in promoters of NBS-encoding genes.

A novel spectrofluorimetric method has been developed for the simultaneous determination of leucomalachite green (LMG), leucocrystal violet (LCV), malachite green (MG) and crystal violet (CV) by combining the sensitivity of molecular fluorescence and the selectivity of the second-order calibration. Residues of LMG, LCV, MG and CV were simultaneously extracted from fish and shrimp muscle with acetonitrile. The non-fluorescent CV and MG were then reduced to the corresponding fluorescent LMG and LCV by reacting with sodium borohydride. After preconcentration with dispersive liquid–liquid microextraction technique, the extracts were analyzed by using excitation–emission matrix fluorescence coupled with second-order calibration methods based on parallel factor analysis (PARAFAC) and alternating trilinear decomposition (ATLD) algorithms. The limits of detection obtained were 2.21–2.65 ng g−1 by PARAFAC and 2.30–2.86 ng g−1 by ATLD, respectively. The developed method was successfully applied to simultaneous determination of the four analytes in grass carp and shrimp samples with recoveries of 90.53–103.03% for PARAFAC and 90.40–102.75% for ATLD. The accuracy of this novel method was also verified by high performance liquid chromatography.

A novel core-shell magnetic nano-sorbent with surface molecularly-imprinted polymer coating was prepared via a sol-gel process. Methyltrimethoxysilane and 3-aminopropyltriethoxysilane were used as functional monomers, tetraethyl orthosilicate as cross-linker, and Al(3+) as dopant to generate Lewis acid sites in the silica matrix for the metal coordinate interactions with the template dimetridazole (DMZ). The ratios of the monomers, the dopant, and the cross-linker, were optimised by a OA9 (3(4)) orthogonal array design. The resultant sorbent was characterised by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, and magnetometry. The binding performances of the sorbent were evaluated by static, kinetic and selective adsorption experiments. The nano-sorbent was successfully applied to solid phase extraction followed by spectrophotometric determination of DMZ in real samples. Spiked recoveries ranged from 90.33% to 106.20% for egg, milk powder, and pig feed samples, with relative standard deviations of less than 4.54%.