ABSTRACT
Chinese cabbage (Brassica rapa L. ssp. pekinensis), in the family Brassicaceae, is a widely planted crop in China valued for its nutritional benefits. In May 2023, wilt symptoms on Chinese cabbage (cv. 'Dongtian118') were observed in several commercial fields located in Sheqi County, (32.47ºN, 112.46ºE), Nanyang, Henan Province, China. A disease survey noted that disease incidence on plants was approximately 20% to 50% within observed fields. Symptoms included yellowing and wilting leaves, and vascular discoloration of the stem bases. To isolate the pathogen, ten symptomatic leaves collected from different diseased cabbage in two field were cut into small pieces (5 × 5 mm), surface disinfected with 75% ethanol for 30 s, then washed three times in sterile water. After drying, tissues were transferred onto potato dextrose agar (PDA). Plates were incubated at 28â for 7 days in the dark. Twelve morphologically similar fungal isolates were obtained by single-spore subculture. The mycelia on PDA were originally white, later becoming dark gray due to the formation of masses of melanized chlamydospores after 15 days of culture. Conidiophores were hyaline and most had secondary branches. In addition, verticillate branches had three to four phialides in each whorl. The conidia were hyaline, elliptical or nearly circular, measuring from 3.2 to 9.5 × 2.6 to 3.8 µm (n=40). These morphological characteristics were similar to those described for Gibellulopsis nigrescens (Zare et al. 2007). The isolates were further identified based on PCR amplification. The ITS, GAPDH, and TEF1 genes were amplified using primers ITS1/ITS4, VGPDf2/VGPDr (Inderbitzin et al. 2011) and EF-2/EF1-728F (O'Donnell et al. 1998). BLAST analysis revealed 12 isolates were highly similar to G. nigrescens, with 99.82% similarity for ITS (OR818474, KJ534578), 93.17% similarity for GAPDH (JN188192.1, JN188166.1) and 91.07% similarity for TEF1 (EF543798.1, EF543804.1). Sequences of the representative isolate BC230515 were deposited into NCBI GenBank with accession nos. OR889646 for ITS and PP135039 for GAPDH. Pathogenicity of all 12 isolates was tested on potted Chinese cabbage plants (cv. 'Dongtian118'). Twenty-four healthy Chinese cabbage plants were inoculated by applying a 10 mL conidial suspension (1×107 conidial/mL) at the artificially wounded root region of each plant. Twenty-four control plants wounded similarly were treated with sterile distilled water. All plants were kept in a growth chamber at 22~25°C (day)/18~20°C (night) , 85% relative humidity and a photoperiod of 12 h per day. After 15 days, inoculated plants exhibited wilting symptoms similar to those observed in the field, whereas control plants remained healthy. The pathogenicity test was repeated three times. The associated fungus on the artificially inoculated plants was reisolated from the symptomatic leaves, and its identity was confirmed by PCR with the primers described above. Reisolated G. nigrescens had identical morphological and molecular characteristics to the original isolates, confirming Koch's postulates. To our knowledge, this is the first report of G. nigrescens causing yellowing and wilt of Chinese cabbage in China. G. nigrescens is a destructive pathogen with multiple hosts such as beet (Zhou et al. 2017), alfalfa (Hu et al. 2011), prevention and control measures should be taken in advance.
ABSTRACT
Corynespora leaf spot, caused by Corynespora cassiicola, is a foliar disease in cucumber. While the application of quinone outside inhibitors (QoIs) is an effective measure for disease control, it carries the risk of resistance development. In our monitoring of trifloxystrobin resistance from 2008 to 2020, C. cassiicola isolates were categorized into three populations: sensitive isolates (S, 0.01 < EC50 < 0.83 µg/mL), moderately resistant isolates (MR, 1.18 < EC50 < 55.67 µg/mL), and highly resistant isolates (HR, EC50 > 56.98 µg/mL). The resistance frequency reached up to 90% during this period, with an increasing trend observed in the annual average EC50 values of all the isolates. Analysis of the CcCytb gene revealed that both MR and HR populations carried the G143A mutation. Additionally, we identified mitochondrial heterogeneity, with three isolates carrying both G143 and A143 in MR and HR populations. Interestingly, isolates with the G143A mutation (G143A-MR and G143A-HR) displayed differential sensitivity to QoIs. Further experiments involving gene knockout and complementation demonstrated that the major facilitator superfamily (MFS) transporter (CcMfs1) may contribute to the disparity in sensitivity to QoIs between the G143A-MR and G143A-HR populations. However, the difference in sensitivity caused by the CcMfs1 transporter is significantly lower than the differences observed between the two populations. This suggests additional mechanisms contributing to the variation in resistance levels among C. cassiicola isolates. Our study highlights the alarming level of trifloxystrobin resistance in C. cassiicola in China, emphasizing the need for strict prohibition of QoIs use. Furthermore, our findings shed light on the occurrence of both target and non-target resistance mechanisms associated with QoIs in C. cassiicola.
Subject(s)
Acetates , Ascomycota , Fungicides, Industrial , Imines , Strobilurins/pharmacology , Fungicides, Industrial/pharmacology , Drug Resistance, Fungal/genetics , Plant DiseasesABSTRACT
Cucumber leaf spot (CLS), caused by Corynespora cassiicola, is a serious disease of greenhouse cucumbers. With frequent use of existing fungicides, C. cassiicola has developed resistance to some of them, with serious implications for the control of CLS in the field. With a lack of new fungicides, it is necessary to use existing fungicides for effective control. Therefore, this study monitored the resistance of C. cassiicola to three commonly used and effective fungicides, boscalid, trifloxystrobin, and carbendazim, from 2017 to 2021. The frequency of resistance to boscalid showed an increasing trend, and the highest frequency was 85.85% in 2020. The frequency of resistance to trifloxystrobin was greater than 85%, and resistance to carbendazim was maintained at 100%. Among these fungicides, strains with multiple resistance to boscalid, trifloxystrobin, and carbendazim were found, accounting for 32.00, 25.25, 33.33, 43.06, and 37.24%, respectively. Of the strains that were resistant to boscalid, 87% had CcSdh mutations, including seven genotypes: B-H278L/Y, B-I280V, C-N75S, C-S73P, D-D95E, and D-G109V. Also, six mutation patterns of the Ccß-tubulin gene were detected: E198A, F167Y, E198A&M163I, E198A&F167Y, M163I&F167Y, and E198A&F200C. Detection of mutations of the CcCytb gene in resistant strains showed that 98.8% were found to have only the G143A mutation. A total of 27 mutation combinations were found and divided into 14 groups for analysis. The resistance levels differed according to genotype. The development of genotypes showed a complex trend, increasing from 4 in 2017 to 13 in 2021 and varying by region. Multiple fungicide resistance is gradually increasing. Therefore, it is necessary to understand the types of mutations and the trend of resistance to guide the use of fungicides to achieve disease control.
Subject(s)
Acetates , Ascomycota , Benzimidazoles , Biphenyl Compounds , Carbamates , Cucumis sativus , Fungicides, Industrial , Imines , Niacinamide/analogs & derivatives , Strobilurins , Fungicides, Industrial/pharmacology , Plant Diseases , ChinaABSTRACT
Quinone outside inhibitor fungicides (QoIs) are crucial fungicides for controlling plant diseases, but resistance, mainly caused by G143A, has been widely reported with the high and widespread use of QoIs. However, two phenotypes of Corynespora casiicola (RI and RII) with the same G143A showed significantly different resistance to QoIs in our previous study, which did not match the reported mechanisms. Therefore, transcriptome analysis of RI and RII strains after trifloxystrobin treatment was used to explore the new resistance mechanism in this study. The results show that 332 differentially expressed genes (DEGs) were significantly up-regulated and 448 DEGs were significantly down-regulated. The results of GO and KEGG enrichment showed that DEGs were most enriched in ribosomes, while also having enrichment in peroxide, endocytosis, the lysosome, autophagy, and mitophagy. In particular, mitophagy and peroxisome have been reported in medicine as the main mechanisms of reactive oxygen species (ROS) scavenging, while the lysosome and endocytosis are an important organelle and physiological process, respectively, that assist mitophagy. The oxidative stress experiments showed that the oxidative stress resistance of the RII strains was significantly higher than that of the RI strains: specifically, it was more than 1.8-fold higher at a concentration of 0.12% H2O2. This indicates that there is indeed a significant difference in the scavenging capacity of ROS between the two phenotypic strains. Therefore, we suggest that QoIs' action caused a high production of ROS, and that scavenging mechanisms such as mitophagy and peroxisomes functioned in RII strains to prevent oxidative stress, whereas RI strains were less capable of resisting oxidative stress, resulting in different resistance to QoIs. In this study, it was first revealed that mitophagy and peroxisome mechanisms available for ROS scavenging are involved in the resistance of pathogens to fungicides.
ABSTRACT
Graphene cladded cobalt phosphide nanoparticles with a sandwich structure are synthesized using Ar-H2-P plasma. In situ phosphorization and graphene reduction are achieved at the same time. Benefitting from the sandwich structure and heterointerface between CoP and RGO, the electrode delivered a high reversible capacity and durable lifespan for both lithium and sodium storage.
ABSTRACT
Two natural carbon sources, glutamic acid and tyrosine, were used to fabricate strong green emission nitrogen-doped graphene quantum dots (N-GQDs) with the one-pot pyrolysis method. The morphology of the prepared GQDs has been characterized by high-resolution transmission electron microscopy, showing a well-displayed crystalline structure with a lattice spacing of 0.262 nm. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to analyze the surface functional groups and elemental composition, suggesting that the N-GQDs have active carboxylic and amino functional groups. Meanwhile, photoluminescence and ultraviolet-visible (UV-vis) spectroscopy were used to evaluate the optical properties of GQDs; the prepared N-GQDs show an excitation-dependent fluorescence behavior with a maximum excitation/emission wavelength at 460/522 nm, respectively. N-GQDs showed good photostability and the fluorescence intensity quenched about 10% after irradiating 2800 s in the experiment of time kinetic analysis. The MTT assay was utilized to assess the viability of N-GQDs; good biocompatibility with a relatively high quantum yield of 12% demonstrated the potential for serving as bioimaging agents. Besides, the selectivity study on metal ions indicates that the N-GQDs could be used in Cu2+ detection. The linear range is from 0.1 to 10 µM with a limit of detection of 0.06 µM. Overall, these proposed N-GQDs with one-pot synthesis showed their promising potential in cell imaging and Cu2+ monitoring applications involved in the biological environment.
ABSTRACT
Cucumber leaf spot, caused by Corynespora cassiicola, is a serious disease of cucumbers in greenhouses. Due to the frequent application of succinate dehydrogenase inhibitors (SDHIs), resistance caused by point mutations in the SDHB/C/D gene has been reported. Different mutations lead to different resistance levels, and mutations vary over time and regions. This means that it is necessary to know the type of mutation in the field to select the appropriate SDHIs. Here, the sensitivity of mutations to SDHIs was determined, and eight resistance patterns were obtained: pattern I (BosVHR, FluoMR, PenHR, CarR); pattern II (BosMR, FluoSS, PenS, CarS); pattern III (BosVHR, FluoSS, PenLR, CarS); pattern IV (BosLR, FluoLR, PenS, CarR); pattern V (BosMR, FluoLR, PenS, CarS); pattern VI (BosMR, FluoLR, PenLR, CarS); pattern VII (BosVHR, FluoHR, PenHR, CarS); and pattern VIII (BosLR, FluoLR, PenLR, CarS). We successfully established nine allele-specific PCR (AS-PCR) assays that can detect mutation types. The sensitivity and specificity of AS-PCR were also determined. The sensitivity results showed that most of the detection thresholds of the AS-PCR assays were 100 pg/µl, while the AS-PCR assay of the B-H278R and D-G109V mutations exhibited high sensitivity, with 10 pg/µl. To validate the use of the developed AS-PCR assay, DNA from leaves inoculated with known mutations was extracted, detected by AS-PCR, and sequenced. The results showed good similarity between the two methods. Additionally, to rapidly detect mutations in the CcSdhD gene, we developed a single-tube multiplex allele-specific PCR (MAS-PCR) assay. In conclusion, AS-PCR and MAS-PCR were established for mutation detection and targeted control of CLS.
Subject(s)
Cucumis sativus , Fungicides, Industrial , Succinic Acid , Succinate Dehydrogenase/genetics , Fungicides, Industrial/pharmacology , Mutation , SuccinatesABSTRACT
In general, ß-casein is a stable molecular chaperone. However, the fact that amyloid fibrils derived from ß-casein has been reported in some cases, which were usually associated with some malignant breast diseases. As an important amino acid, arginine not only exhibits the significance in casein synthesis in mammary gland, but also has great potentiality in inhibiting the amyloid fibril formation. Therefore, the influence of arginine on the amyloid fibrils formed by ß-casein and further molecular mechanism were studied firstly with multi-spectroscopic techniques in the present work. The results of Thioflavin T determination, particle size analysis, transmission electron microscope observation showed that arginine not only inhibited the aggregation of ß-casein at the growth stage, but also depolymerized the mature amyloid fibrils at the saturation stage. The further fluorescence experiment results demonstrated that the complex was formed between ß-casein and arginine. Besides, there was one binding site and 0.48 nm binding distance. The thermodynamic parameters like ΔG0, ΔS0, ΔH0 were all negative, showing their binding reaction was spontaneous, and hydrogen bond and van der Waals force were the possibly chief intermolecular forces. Furthermore, the synchronous fluorescence spectra showing that the conformation of ß-casein was affected and its tyrosine residues were gradually buried inside the protein. Our research would provide new insights into the treatments for the breast amyloidosis.
Subject(s)
Amyloid , Caseins , Amyloid/chemistry , Amyloid beta-Peptides , Arginine , Caseins/chemistry , Spectrum Analysis , ThermodynamicsABSTRACT
Corynespora leaf spot caused by Corynespora cassiicola is an important foliar disease in cucumber. Succinate dehydrogenase inhibitors are the main fungicides used to control this disease. With the application of succinate dehydrogenase inhibitors (SDHIs) in the field, boscalid-resistant isolates have been continuously detected in the field. Resistance monitoring programs were performed to investigate the frequency and genotypes of resistant isolates. In our resistance monitoring, the frequency of resistant isolates rapidly increased from 9.68 to 85.88% in 2005 to 2020. Nine genotypes conferring SDHI resistance were found in resistant isolates, with different levels of resistance to SDHIs: B-H278R, B-H278L, B-H278Y, B-I280V, C-N75S, C-S73P, D-D95E, D-H105R, and D-G109V. The first sdh mutation was detected in Hebei Province in China, conferring an amino acid substitution at codon 278 in the sdhB subunit from histidine to tyrosine (B-H278Y), and it was the dominant resistance genotype in 2014 to 2015. Subsequently, other genotypes were gradually detected in the field, and the dominant mutations varied across years and across regions. The newest genotype (B-H278L) conferring SDHI resistance was found in 2020. To the best of our knowledge, this is the first report of C. cassiicola in cucumber. To date, multiple resistance to SDHIs, quinone outside inhibitors, benzimidazole fungicides, and dicarboximide fungicides have been detected, accounting for 75.64% of SDHI-resistant isolates. Therefore, the above four fungicides must be strictly restricted, and further monitoring work in other provinces with more isolates should be performed in the future.
Subject(s)
Cucumis sativus , Fungicides, Industrial , Ascomycota , Biphenyl Compounds , Drug Resistance, Fungal/genetics , Fungicides, Industrial/pharmacology , Niacinamide/analogs & derivatives , Plant Diseases , Succinate Dehydrogenase/geneticsABSTRACT
With the further application of succinate dehydrogenase inhibitors (SDHI), the resistance caused by double mutations in target gene is gradually becoming a serious problem, leading to a decrease of control efficacy. It is important to assess the sensitivity and fitness of double mutations to SDHI in Corynespora cassiicola and analysis the evolution of double mutations. We confirmed, by site-directed mutagenesis, that all double mutations (B-I280V+D-D95E/D-G109V/D-H105R, B-H278R+D-D95E/D-G109V, B-H278Y+D-D95E/D-G109V) conferred resistance to all SDHI and exhibited the increased resistance to at least one fungicide than single point mutation. Analyses of fitness showed that all double mutations had lower fitness than the wild type; most of double mutations suffered more fitness penalties than the corresponding single mutants. We also further found that double mutations (B-I280V+D-D95E/D-G109V/D-H105R) containing low SDHI-resistant single point mutation (B-I280V) exhibited higher resistance to SDHI and low fitness penalty than double mutations (B-H278Y+D-D95E/D-G109V) containing high SDHI-resistant single mutations (B-H278Y). Therefore, we may infer that a single mutation conferring low resistance is more likely to evolve into a double mutation conferring higher resistance under the selective pressure of SDHI. Taken together, our results provide some important reference for resistance management.
ABSTRACT
The impaired wound healing in diabetes is a central concern of healthcare worldwide. However, current treatments often fail due to the complexity of diabetic wounds, and thus, emerging therapeutic approaches are needed. Macrophages, a prominent immune cell in the wound, play key roles in tissue repair and regeneration. Recent evidence has demonstrated that macrophages in diabetic wounds maintain a persistent proinflammatory phenotype that causes the failure of healing. Therefore, modulation of macrophages provides great promise for wound healing in diabetic patients. In this study, the potential of paeoniflorin (PF, a chemical compound derived from the herb Paeonia lactiflora) for the transition of macrophages from M1 (proinflammatory phenotype) to M2 (anti-inflammatory/prohealing phenotype) was confirmed using ex vivo and in vivo experimental approaches. A hydrogel based on high molecular weight hyaluronic acid (HA) was developed for local administration of PF in experimental diabetic mice with a full-thickness wound. The resultant formulation (HA-PF) was able to significantly promote cutaneous healing as compared to INTRASITE Gel (a commercial hydrogel wound dressing). This outcome was accompanied by the amelioration of inflammation, the improvement of angiogenesis, and re-epithelialization, and the deposition of collagen. Our study indicates the significant potential of HA-PF for clinical translation in diabetic wound healing.
ABSTRACT
Docetaxel (DTX) is a chemotherapeutic agent used for a range of cancers, but it has little activity against colorectal cancer (CRC). However, combination therapy with other therapeutic agents is a potential strategy to enhance the efficacy of DTX in CRC treatment. The nuclear factor-κB (NF-κB) signaling pathway is implicated in a variety of malignancies (e.g., CRC), and the blockade of NF-κB may increase the sensitivity of cancer cells to chemotherapy. The application of small interference RNA (siRNA) to inhibit the translation of complementary mRNA has demonstrated the potential for cancer gene therapy. In this study, an amphiphilic cationic cyclodextrin (CD) nanoparticle modified with PEGylated folate (FA; a ligand to target folate receptor on CRC) has been developed for co-delivery of DTX and siRNA (against the RelA, a subunit of NF-κB) in the treatment of CRC. The resultant co-formulation (CD.DTX.siRelA.PEG-FA) achieved cell-specific uptake indicating the function of the folate targeting ligand. The CD.DTX.siRelA.PEG-FA nanoparticle enhanced the apoptotic effect of DTX with the downregulation of RelA expression, which significantly retarded the growth of CRC in mice, without causing significant toxicity. These results suggest that the FA-targeted PEGylated CD-based co-formulation provides a promising strategy for combining DTX and siRNA in treating CRC.
Subject(s)
Antineoplastic Agents , Colorectal Neoplasms , Cyclodextrins , Nanoparticles , Animals , Cell Line, Tumor , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/genetics , Docetaxel , Folic Acid , Mice , Polyethylene Glycols , RNA, Small InterferingABSTRACT
Carboxamide fungicides target succinate dehydrogenase (SDH). Recently published monitoring studies have shown that Corynespora cassiicola isolates are resistant to one or several SDH inhibitors (SDHIs) with amino acid substitutions in the SDH B and D subunits. We confirmed, by site-directed mutagenesis of the sdhB and sdhD genes, that each of the mutations identified in the field strains of C. cassiicola conferred resistance to boscalid and, in some cases, cross-resistance to other SDHIs (fluopyram, carboxin and penthiopyrad). Analyses of the enzyme activity and sdhB and sdhD gene expression show that modifications (SdhB_H278Y and SdhD_H105R) that result in a decline in SDH enzyme activity may be complemented by gene overexpression. The SdhB_H278Y, SdhB_I280V and SdhD_H105R mutants suffered large fitness penalties based on their biological properties, including conidia production and germination, mycelial growth, pathogenicity or survival abilities under environment stress. However, fitness cost was not found in the SdhB_H278R, SdhD_D95E and SdhD_G109V mutants. In the evaluation of resistance to boscalid in 2018 and 2019, the frequency of the SdhD_D95E and SdhD_G109V genotypes in the Liaoning and Shandong provinces changed dramatically compared with 2005-2017, from low resistance frequency (0.53% for D95E and 2.53% for G109V) to dominant resistance frequency (17.28% for D95E and 15.38% for G109V). Considering both the fitness and increased frequency of these genotypes, we may infer that the SdhD_D95E and SdhD_G109V mutants will be the dominant resistance mutants in field.
Subject(s)
Drug Resistance, Fungal , Succinate Dehydrogenase , Ascomycota , Drug Resistance, Fungal/genetics , Fungal Proteins/genetics , Mutagenesis, Site-Directed , Plant Diseases , Succinate Dehydrogenase/genetics , Succinate Dehydrogenase/metabolismABSTRACT
BACKGROUND: For Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei, a necrotrophic pathogen with a broad host range and a worldwide distribution, resistance to fluopyram has been attributed to mutations in SdhB/C/D subunit of the succinate dehydrogenase (SDH) complex. In our previous study, two point mutations in SdhB from isoleucine to valine at position 280 (I280V) and histidine to tyrosine at position 278 (H278Y) showed different resistance phenotypes to fluopyram and boscalid. This research was conducted to explore the correlation between the mutation of SdhB-I280V or SdhB-H278Y and resistance to fluopyram or boscalid and its effect on the fitness characteristics of C. cassiicola. RESULTS: The sdhB gene in a succinate dehydrogenase inhibitor (SDHI)-sensitive C. cassiicola strain (wild type) was successfully replaced with the mutant sdhB gene (GTT at position 280, SdhB-I280V) or with the mutant sdhB gene (TAC at position 278, SdhB-H278Y,). Compared with the wild-type strain, the replacement mutants exhibited significantly different resistance phenotypes, with SdhB-V280 demonstrating moderate resistance to fluopyram and low resistance to boscalid, while SdhB-Y278 was supersensitive to fluopyram and very highly resistant to boscalid. Both of the mutants exhibited decreased sensitivity to salt stress and increased SDH activity. These two mutations had no effect on the mycelial growth rate, sporulation ability, pathogenicity in vivo, sensitivity to osmotic stress and oxidative stress, cell wall damaging agents, or SHAM. CONCLUSION: Two adjacent mutations in the SdhB gene conferred different resistance phenotypes to SDHIs in C. cassiicola, which is important for the development of alternative antifungal fungicides and fluopyram resistance management. © 2021 Society of Chemical Industry.
Subject(s)
Fungicides, Industrial , Succinate Dehydrogenase , Ascomycota , Benzamides , Drug Resistance, Fungal/genetics , Fungal Proteins/genetics , Fungal Proteins/metabolism , Fungicides, Industrial/pharmacology , Mutation , Phenotype , Plant Diseases , Pyridines , Succinate Dehydrogenase/genetics , Succinate Dehydrogenase/metabolismABSTRACT
Phosphorus-rich metal phosphides have very high lithium storage capacities, but they are difficult to prepare. A low-temperature phosphorization method based on Mg reducing PCl3 in ZnCl2 molten salt at 300 °C is developed to synthesize phosphorus-rich CuP2 @C from a Cu-MOF derived Cu@C composite. Abnormal oxidation of Cu by Zn2+ in the molten salt is observed, which leads to the porous honeycomb nanostructure and homogeneously distributed ultrafine CuP2 nanocrystals. The honeycomb CuP2 @C exhibits excellent lithium storage performance with high reversible capacity (1146â mAh g-1 at 0.2â A g-1 ) and superior cycling stability (720â mAh g-1 after 600 cycles at 1.0â A g-1 ), showing the promising application of P-rich metal phosphides in lithium ion batteries.
ABSTRACT
While nickel phosphide is a highly attractive catalyst for the hydrogen evolution reaction, its preparation requires either high temperature or the use of highly toxic PH3 directly or indirectly. Herein, we demonstrate that H2 plasma activated red phosphorus enables the synthesis of self-supported Ni2P nanosheet (Ni2P/NF) arrays on commercial nickel foam from a NiO/NF precursor at only 250 °C. Highly reactive atomic H in the plasma induces dissociation of the P4 molecules, yielding an acid stable electrode with excellent hydrogen evolution activity and good mechanical strength.
ABSTRACT
Hydrogenation of N-heterocycles is of great significance for their wide range of applications such as building blocks in drug and agrochemical syntheses and liquid organic hydrogen carriers (LOHCs). Pursuing a better hydrogenation performance and stereoselectivity, we successfully developed a rare earth hydride supported ruthenium catalyst Ru/YH3 for the hydrogenation of N-heterocycles, especially N-ethylcarbazole (NEC), the most promising LOHC. Full hydrogenation of NEC on Ru/YH3 can be achieved at 363 K and 1 MPa hydrogen pressure, which is currently the lowest compared to previous reported catalysts. Furthermore, Ru/YH3 shows the highest turnover number, namely the highest catalytic activity among the existing catalysts for hydrogenation of NEC. Most importantly, Ru/YH3 shows remarkable stereoselectivity for all-cis products, which is very favorable for the subsequent dehydrogenation. The excellent performance of Ru/YH3 originates from the new hydrogen transfer path from H2 to NEC via YH3. Ru/LaH3 and Ru/GdH3 also reveal good activity for hydrogenation of NEC and Ru/YH3 also possesses good activity for hydrogenation of 2-methylindole, indicating that the use of rare earth hydride supported catalysts is a highly effective strategy for developing better hydrogenation catalysts for N-heterocycles.
ABSTRACT
We developed self-microemulsifying drug-delivery systems (SMEDDS), including bile salts, to improve the oral bioavailability of pueraria flavones (PFs). The physical properties of the SMEDDS using Cremophor RH 40, and bile salts as mixed surfactants at weight ratios of 10:0â»0:10 were determined. The particle sizes of PFs-SMEDDSNR containing sodium taurocholate (NaTC) and Cremophor RH 40, and PFs-SMEDDSR containing Cremophor RH 40 were measured upon dilution with deionized water and other aqueous media. Dilution volume presented no remarkable effects on particle size, whereas dilution media slightly influenced particle size. PFs-SMEDDSNR and PFs-SMEDDSR provided similar release rates in pH-1.2 hydrochloride solution. However, the release rate of PFs-SMEDDSNR was faster than that of PFs-SMEDDSR in pH-6.8 phosphate buffer containing 20 mM NaTC and 500 U/mL porcine pancreas lipase. The pharmacokinetics and bioavailability were measured in rats. The oral bioavailability of PFs-SMEDDSNR was 2.57- and 2.28-fold that of a suspension of PFs (PFs-suspension) before and after the blockade of the lymphatic transport route by cycloheximide, respectively. These results suggested PFs-SMEDDSNR could significantly improve the oral relative absorption of PFs via the lymphatic uptake pathway. SMEDDS containing NaTC may provide an effective approach for enhancing the oral bioavailability of PFs.
ABSTRACT
A mild phosphorization process in low-temperature molten salt (NaCl-KCl-AlCl3 ) has been developed to synthesize peapod-like CoP@C nanostructures by using low-toxicity industrial PCl3 as the phosphorus source and Mg as the reductant at 250 °C. Importantly, high efficiency of the phosphorous source is achieved since only stoichiometric PCl3 is required to complete the reaction. The molten NaCl-KCl-AlCl3 not only provides a liquid environment but also participates in the electron transport by the reversible conversion of the Al3+ /Al redox couple. The obtained 0D-in-1D peapod CoP@C structure exhibits excellent lithium storage performance, delivering a superiorly stable capacity of 500â mAh g-1 after 800 cycles at a high current of 1.0â A g-1 .
ABSTRACT
SiCl4 can be directly reduced to nano-Si with commercial Na metal under solvent-free conditions by mechanical milling. Crystalline nano-Si with an average size of 25 nm and quite uniform size distribution can be obtained, which shows excellent lithium storage performance, for a high reversible capacity of 1600 mA h g-1 after 500 cycles at 2.1 A g-1.