Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 75
Filtrar
1.
Nature ; 565(7741): 631-635, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30700869

RESUMO

Proton-exchange-membrane fuel cells (PEMFCs) are attractive next-generation power sources for use in vehicles and other applications1, with development efforts focusing on improving the catalyst system of the fuel cell. One problem is catalyst poisoning by impurity gases such as carbon monoxide (CO), which typically comprises about one per cent of hydrogen fuel2-4. A possible solution is on-board hydrogen purification, which involves preferential oxidation of CO in hydrogen (PROX)3-7. However, this approach is challenging8-15 because the catalyst needs to be active and selective towards CO oxidation over a broad range of low temperatures so that CO is efficiently removed (to below 50 parts per million) during continuous PEMFC operation (at about 353 kelvin) and, in the case of automotive fuel cells, during frequent cold-start periods. Here we show that atomically dispersed iron hydroxide, selectively deposited on silica-supported platinum (Pt) nanoparticles, enables complete and 100 per cent selective CO removal through the PROX reaction over the broad temperature range of 198 to 380 kelvin. We find that the mass-specific activity of this system is about 30 times higher than that of more conventional catalysts consisting of Pt on iron oxide supports. In situ X-ray absorption fine-structure measurements reveal that most of the iron hydroxide exists as Fe1(OH)x clusters anchored on the Pt nanoparticles, with density functional theory calculations indicating that Fe1(OH)x-Pt single interfacial sites can readily react with CO and facilitate oxygen activation. These findings suggest that in addition to strategies that target oxide-supported precious-metal nanoparticles or isolated metal atoms, the deposition of isolated transition-metal complexes offers new ways of designing highly active metal catalysts.

2.
J Exp Bot ; 75(13): 4052-4073, 2024 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-38497908

RESUMO

The glutamine synthetase/glutamic acid synthetase (GS/GOGAT) cycle plays important roles in N metabolism, growth, development, and stress resistance in plants. Excess ammonium (NH4+) restricts growth, but GS can help to alleviate its toxicity. In this study, the 84K model clone of hybrid poplar (Populus alba × P. tremula var. glandulosa), which has reduced biomass accumulation and leaf chlorosis under high-NH4+ stress, showed less severe symptoms in transgenic lines overexpressing GLUTAMINE SYNTHETASE 1;2 (GS1;2-OE), and more severe symptoms in RNAi lines (GS1;2-RNAi). Compared with the wild type, the GS1;2-OE lines had increased GS and GOGAT activities and higher contents of free amino acids, soluble proteins, total N, and chlorophyll under high-NH4+ stress, whilst the antioxidant and NH4+ assimilation capacities of the GS1;2-RNAi lines were decreased. The total C content and C/N ratio in roots and leaves of the overexpression lines were higher under stress, and there were increased contents of various amino acids and sugar alcohols, and reduced contents of carbohydrates in the roots. Under high-NH4+ stress, genes related to amino acid biosynthesis, sucrose and starch degradation, galactose metabolism, and the antioxidant system were significantly up-regulated in the roots of the overexpression lines. Thus, overexpression of GS1;2 affected the carbon and amino acid metabolism pathways under high-NH4+ stress to help maintain the balance between C and N metabolism and alleviate the symptoms of toxicity. Modification of the GS/GOGAT cycle by genetic engineering is therefore a potential strategy for improving the NH4+ tolerance of cultivated trees.


Assuntos
Compostos de Amônio , Carbono , Glutamato-Amônia Ligase , Nitrogênio , Plantas Geneticamente Modificadas , Populus , Populus/genética , Populus/metabolismo , Populus/enzimologia , Glutamato-Amônia Ligase/metabolismo , Glutamato-Amônia Ligase/genética , Nitrogênio/metabolismo , Carbono/metabolismo , Compostos de Amônio/metabolismo , Compostos de Amônio/toxicidade , Plantas Geneticamente Modificadas/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas
3.
Inflamm Res ; 73(2): 277-287, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38184814

RESUMO

AIMS: Inflammatory bowel disease (IBD) is a global disease. We aim to summarize the latest epidemiological patterns of IBD at the national, regional and global levels to give well-deserved attention and outline facilitating measures to reduce the disease burden. METHODS: We collected the incidence, prevalence, mortality and disability-adjusted life years (DALYs) of IBD in 204 countries and territories from 1990 to 2019 using data from the Global Burden of Disease Study 2019. We further calculated the estimated annual percentage change (EAPC) to qualify the temporal trends of IBD burden by sex, age and region over the past 30 years. RESULTS: Globally, a total of 404.55 thousand incident cases, 4898.56 thousand prevalent cases, 41.00 thousand deaths and 1622.50 thousand DALYs of IBD were estimated in 2019. The age-standardized DALYs decreased from 27.2 in 1990 to 20.15 per 100,000 people in 2019, with an EAPC of -1.04. The high socio-demographic index regions presented pronounced age-standardized rates (ASRs) consistently over the last 30 years. The high-income North America had the highest ASRs in 2019, followed by Western Europe and Australasia. No gender difference was observed after being stratified by sex. CONCLUSIONS: The accumulated IBD patients are expected to increase in the future due to the increased rate of IBD in developing countries, and social aging in developed countries. Understanding the changes in epidemiological patterns helps to provide evidence to mitigate the rising burden of IBD.


Assuntos
Carga Global da Doença , Doenças Inflamatórias Intestinais , Humanos , Adulto , Anos de Vida Ajustados por Qualidade de Vida , Saúde Global , Prevalência , Doenças Inflamatórias Intestinais/epidemiologia
4.
Int J Mol Sci ; 25(2)2024 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-38256092

RESUMO

Secondary development is a key biological characteristic of woody plants and the basis of wood formation. Exogenous nitrogen can affect the secondary growth of poplar, and some regulatory mechanisms have been found in the secondary xylem. However, the effect of nitrogen on cambium has not been reported. Herein, we investigated the effects of different nitrogen concentrations on cambium development using combined transcriptome and metabolome analysis. The results show that, compared with 1 mM NH4NO3 (M), the layers of hybrid poplar cambium cells decreased under the 0.15 mM NH4NO3 (L) and 0.3 mM NH4NO3 (LM) treatments. However, there was no difference in the layers of hybrid poplar cambium cells under the 3 mM NH4NO3 (HM) and 5 mM NH4NO3 (H) treatments. Totals of 2365, 824, 649 and 398 DEGs were identified in the M versus (vs.) L, M vs. LM, M vs. HM and M vs. H groups, respectively. Expression profile analysis of the DEGs showed that exogenous nitrogen affected the gene expression involved in plant hormone signal transduction, phenylpropanoid biosynthesis, the starch and sucrose metabolism pathway and the ubiquitin-mediated proteolysis pathway. In M vs. L, M vs. LM, M vs. HM and M vs. H, differential metabolites were enriched in flavonoids, lignans, coumarins and saccharides. The combined analysis of the transcriptome and metabolome showed that some genes and metabolites in plant hormone signal transduction, phenylpropanoid biosynthesis and starch and sucrose metabolism pathways may be involved in nitrogen regulation in cambium development, whose functions need to be verified. In this study, from the point of view that nitrogen influences cambium development to regulate wood formation, the network analysis of the transcriptome and metabolomics of cambium under different nitrogen supply levels was studied for the first time, revealing the potential regulatory and metabolic mechanisms involved in this process and providing new insights into the effects of nitrogen on wood development.


Assuntos
Câmbio , Populus , Câmbio/genética , Reguladores de Crescimento de Plantas , Transcriptoma , Metaboloma , Nitrogênio , Populus/genética , Amido , Sacarose
5.
J Integr Plant Biol ; 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38924348

RESUMO

IDEAL PLANT ARCHITECTURE1 (IPA1) is a pivotal gene controlling plant architecture and grain yield. However, little is known about the effects of Triticum aestivum SQUAMOSA PROMOTER-BINDING-LIKE 14 (TaSPL14), an IPA1 ortholog in wheat, on balancing yield traits and its regulatory mechanism in wheat (T. aestivum L.). Here, we determined that the T. aestivum GRAIN WIDTH2 (TaGW2)-TaSPL14 module influences the balance between tiller number and grain weight in wheat. Overexpression of TaSPL14 resulted in a reduced tiller number and increased grain weight, whereas its knockout had the opposite effect, indicating that TaSPL14 negatively regulates tillering while positively regulating grain weight. We further identified TaGW2 as a novel interacting protein of TaSPL14 and confirmed its ability to mediate the ubiquitination and degradation of TaSPL14. Based on our genetic evidence, TaGW2 acts as a positive regulator of tiller number, in addition to its known role as a negative regulator of grain weight, which is opposite to TaSPL14. Moreover, combinations of TaSPL14-7A and TaGW2-6A haplotypes exhibit significantly additive effects on tiller number and grain weight in wheat breeding. Our findings provide insight into how the TaGW2-TaSPL14 module regulates the trade-off between tiller number and grain weight and its potential application in improving wheat yield.

6.
J Am Chem Soc ; 145(12): 6702-6709, 2023 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-36920448

RESUMO

Reactive metal-support interactions (RMSIs) induce the formation of bimetallic alloys and offer an effective way to tune the electronic and geometric properties of metal sites for advanced catalysis. However, RMSIs often require high-temperature reductions (>500 °C), which significantly limits the tuning of bimetallic compositional varieties. Here, we report that an atomically thick Ga2O3 coating of Pd nanoparticles enables the initiation of RMSIs at a much lower temperature of ∼250 °C. State-of-the-art microscopic and in situ spectroscopic studies disclose that low-temperature RMSIs initiate the formation of rarely reported Ga-rich PdGa alloy phases, distinct from the Pd2Ga phase formed in traditional Pd/Ga2O3 catalysts after high-temperature reduction. In the CO2 hydrogenation reaction, the Ga-rich alloy phases impressively boost the formation of methanol and dimethyl ether ∼5 times higher than that of Pd/Ga2O3. In situ infrared spectroscopy reveals that the Ga-rich phases greatly favor formate formation as well as its subsequent hydrogenation, thus leading to high productivity.

7.
Gynecol Obstet Invest ; 88(1): 30-36, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36450266

RESUMO

OBJECTIVES: The objective of this study was to summarize the rate of lymph node metastasis (LNM) of patients with stage IA-IIA cervical cancer and further analyze its distribution characteristics and related risk factors. DESIGN: This study is a retrospective analysis of clinical data about cervical cancer. PARTICIPANTS: According to the International Federation of Gynecology and Obstetrics (FIGO) 2009 staging standard, 975 patients with stage IA-IIA cervical cancer treated in our hospital from January 2010 to December 2018. SETTING: This is a single-center study. METHODS: The incidence and distribution of LNM were analyzed, and the influencing factors of cervical cancer LNM were analyzed using univariate and multivariate logistic regression. RESULTS: In this study, the LNM rate was 14.8% (144/975), and a total of 20,288 lymph nodes were removed, among which 359 lymph nodes had metastasis. According to the number and frequency of metastatic lymph nodes in different regions, the metastatic rate was the highest in the external iliac regions. Univariate analysis showed that more than three pregnancies, tumor size >4 cm, gross type, FIGO stage, pathological type, positive lymphovascular space invasion (LVSI), deep cervical stromal invasion (outer half invasion), parametrial involvement, and uterine corpus invasion (UCI) were correlated with LNM (p < 0.05). Multivariate analysis showed that tumor lesion of >4 cm (odds ratio (OR) = 2.253, 95% confidence interval (CI): 1.486-3.416, p < 0.001), positive LVSI (OR = 5.353, 95% CI: 3.303-8.676, p < 0.001), deep cervical stromal invasion (OR = 3.461, 95% CI: 2.106-5.688, p < 0.001), and deep UCI (myometrial invasion ≥50%) (OR = 3.529, 95% CI: 1.321-9.427, p = 0.012) were independent risk factors for LNM. LIMITATIONS: Retrospective nature of the study and limitation to a single-center study are the limitations of the study. CONCLUSIONS: Patients with cervical cancer are more likely to have LNM with a tumor size of >4 cm, positive LVSI, deep cervical stromal invasion, or deep UCI. When these risk factors are present, the presence of LNM is possible, and attention should be paid. This study provides a certain reference value for predicting LNM risk for patients with early cervical cancer and for the stratified management of early cervical cancer treatment.


Assuntos
Metástase Linfática , Neoplasias do Colo do Útero , Feminino , Humanos , Histerectomia , Excisão de Linfonodo , Linfonodos/patologia , Metástase Linfática/patologia , Estadiamento de Neoplasias , Estudos Retrospectivos , Fatores de Risco , Neoplasias do Colo do Útero/patologia
8.
Anal Chem ; 94(41): 14099-14108, 2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-36197877

RESUMO

Extracellular vesicle (EV) cargos with regular fluctuations hold the potential for providing chemical predictors toward clinical diagnosis and prognosis. A plasma sample is one of the most important sources of circulating EVs, yet the technical barrier and cost consumption in plasma-EV isolation still limit its application in disease diagnosis and biomarker discovery. Here, we introduced an easy-to-use strategy that allows selectively purifying small EVs (sEVs) from human plasma and detecting their metabolic alternations. Fe3O4@TiO2 microbeads with a rough island-shaped surface have proven the capability of performing efficient and reversible sEV capture owing to the phospholipid affinity, enhanced binding sites, and size-exclusion-like effect of the rough TiO2 shell. The proposed system can also shorten the separation procedure from hours to 20 min when compared with the ultracentrifugation method and yield approximately 108 sEV particles from 100 µL of plasma. Metabolome variations of sEVs among progressive diabetic retinopathy subjects were finally studied, observing a cluster of metabolites with elevated levels and suggesting potential roles of these sEV chemicals in diabetic retinopathy onset and progression. Such a scalable and flexible EV capture system can be seen as an effective analytical tool for facilitating plasma-based liquid biopsies.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Vesículas Extracelulares , Biomarcadores/análise , Diabetes Mellitus/metabolismo , Retinopatia Diabética/diagnóstico , Retinopatia Diabética/metabolismo , Vesículas Extracelulares/química , Humanos , Fosfolipídeos/análise , Titânio
9.
Inorg Chem ; 61(18): 6953-6963, 2022 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-35476582

RESUMO

High-performance warm-white light-emitting diode (LED) devices are in great demand toward green and comfortable solid-state lighting. Herein, we report a creative green-emission CaY2HfGa(AlO4)3:Ce3+ phosphor. CaY2HfGa(AlO4)3:Ce3+ compounds with different cerium ion doping contents have been successfully prepared through a conventional high-temperature solid-state method, and their phase and crystal structure have been revealed via the powder X-ray diffraction and Rietveld refinement. Impressively, the CaY2HfGa(AlO4)3:Ce3+ phosphors exhibit a broad-band excitation, which well covers the wavelength region from the 300 to 500 nm, corresponding to the commercial blue-emitting LED chip. Upon 450 nm excitation, the optimal CaY2HfGa(AlO4)3:2%Ce3+ sample shows an intense broad-band green emission (the corresponding testing spectral range: 460-750 nm) with a strongest peak about 534 nm. In addition, the CaY2HfGa(AlO4)3:2%Ce3+ sample possesses a broad full width at half-maximum equal to 120 nm; moreover, its CIE chromaticity coordinate and the internal quantum efficiency are determined to be (0.3541, 0.5427) and 72.8%, respectively. A high-quality warm-white LED has been fabricated through incorporating our CaY2HfGa(AlO4)3:2%Ce3+ green phosphors and commercial red phosphors with the 450 nm blue LED chip. When upon the 20 mA bias driving current, the LED device demonstrates a bright warm-white light emission, which possesses a satisfactory color rendering index of 91, a low correlated color temperature of 4080 K, as well as a good luminous efficacy of 85.14 lm W-1. The creative green-emitting CaY2HfGa(AlO4)3:Ce3+ garnet phosphor has a bright application prospect toward high-quality warm-white LED lighting.

10.
Biochem Genet ; 60(2): 656-675, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34410559

RESUMO

Lignin is essential for the characteristics and quality of timber. Nitrogen has significant effects on lignin contents in plants. Nitrogen has been found to affect wood quality in plantations and lignin content in plants. Caffeoyl-CoA 3-O-methyltransferase (CCoAOMT) is an important methyltransferase in lignin biosynthesis. However, the classification of woody plant CCoAOMT gene family members and the regulation mechanism of nitrogen are not clear. Bioinformatics methods were used to predict the members, classification, and transcriptional distribution of the CCoAOMT gene family in Populus trichocarpa. The results showed that there were five PtCCoAOMTs identified, and they could be divided into three sub-groups according to their structural and phylogenetic features. The results of tissue expression specificity analysis showed that: PtCCoAOMT1 was highly expressed in roots and internodes; PtCCoAOMT2 was highly expressed in roots, nodes, and internodes, PtCCoAOMT3 was highly expressed in stems; PtCCoAOMT4 was highly expressed in young leaves, and, PtCCoAOMT5 was highly expressed in roots. Different forms and concentrations of nitrogen had varying effects on the expression patterns of genes in different plant tissue types. The results of real-time PCR showed that the expression levels of PtCCoAOMT1 and PtCCoAOMT2 in stems increased significantly under different forms of nitrogen. PtCCoAOMT3 and PtCCoAOMT4 were induced by nitrate nitrogen in upper stems and lower leaves, respectively. PtCCoAOMT4 and PtCCoAOMT5 were induced by different concentrations of nitrate nitrogen in lower stems and roots, respectively. These results could provide valuable information for revealing the differences between functions and expression patterns of the various CCoAOMT gene family members under different forms and concentrations of exogenous nitrogen in poplar.


Assuntos
Populus , Regulação da Expressão Gênica de Plantas , Metiltransferases/genética , Nitrogênio/metabolismo , Filogenia , Populus/genética , Populus/metabolismo
11.
J Nurs Scholarsh ; 54(2): 250-257, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34773375

RESUMO

PURPOSE: To explore the ethical experiences of new nurse managers when working at their units and propose response strategies accordingly. DESIGN AND METHODS: A qualitative approach was taken at a Grade 3A hospital in Shandong, China. Data were collected via semi-structured long interviews and analyzed using interpretative phenomenological analysis. A total of 19 new frontline nurse managers participated in the study. FINDINGS: The sample consisted of 17 females and two males, with an age range of 40.11 ± 2.71 years and each worked in a variety of units. Trust crisis, tests on capability, and conflicts with the administration were the main ethical issues of new nurse managers, and trust crisis was the most common, especially with nurses in the unit. Eleven subthemes were also involved in these three themes. CONCLUSIONS: New nurse managers encountered a variety of ethical conflicts and dilemmas in their first year. They should enhance their leadership to cope with the issues, and policy support at the hospital level is also needed. CLINICAL RELEVANCE: Senior hospital managers could use these findings to design interventions that might solve new frontline nurse managers' ethical issues. And medical staff might understand the ethical experiences of new nurse managers and support them in the most critical period of role transition. Findings are conducted in the hope of facilitating new nurse managers to quickly settle into the new position, establishing a good relationship with physicians and patients and improving the quality of nursing services.


Assuntos
Enfermeiros Administradores , Adulto , China , Feminino , Humanos , Liderança , Masculino , Princípios Morais , Confiança
12.
J Am Chem Soc ; 143(45): 18854-18858, 2021 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-34730347

RESUMO

Controlling the chemical environments of the active metal atom including both coordination number (CN) and local composition (LC) is vital to achieve active and stable single-atom catalysts (SACs), but remains challenging. Here we synthesized a series of supported Pt1 SACs by depositing Pt atoms onto the pretuned anchoring sites on nitrogen-doped carbon using atomic layer deposition. In hydrogenation of para-chloronitrobenzene, the Pt1 SAC with a higher CN about four but less pyridinic nitrogen (Npyri) content exhibits a remarkably high activity along with superior recyclability compared to those with lower CNs and more Npyri. Theoretical calculations reveal that the four-coordinated Pt1 atoms with about 1 eV lower formation energy are more resistant to agglomerations than the three-coordinated ones. Composition-wise decrease of the Pt-Npyri bond upshifts gradually the Pt-5d center, and minimal one Pt-Npyri bond features a high-lying Pt-5d state that largely facilitates H2 dissociation, boosting hydrogenation activity remarkably.

13.
Int J Environ Health Res ; 31(1): 34-44, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31145012

RESUMO

This study was designed to investigate the cytotoxicity of lead acetate (Pb(AC)2, a representative air pollutant) by focusing on PPARγ/caspase-3/PARP apoptotic signaling pathway and to explore the inhibitory effect of PPARγ antagonist on apoptosis of TM3 Leydig cells. MTT assay was utilized to examine cell viability. Cell apoptosis was analyzed using a flow cytometry by staining with Annexin V-PE/7AAD staining and a fluorescence microscope by staining with Hoechst 33,258. The levels of apoptosis-related proteins were examined using western blot. From the results, Pb reduced significantly TM3 cell proliferation in concentration- and time-dependent manner. It increased significantly apoptosis; increased the PPARγ, Bax, procaspase-3, cleaved caspase-3, proPARP, cleaved PARP levels; and decreased Bcl-2 level in Pb-treated TM3 cells as compared to control cells. Furthermore, pretreatment with PPARγ antagonist significantly attenuated the apoptosis and cleavage of caspase-3 and PARP induced by Pb. Our results suggested that Pb induced cytotoxicity on TM3 Leydig cells, at least in part, by increasing PPARγ expression, stimulating cleavage of caspase-3 and PARP, and then induced cell apoptosis.


Assuntos
Apoptose/efeitos dos fármacos , Poluentes Ambientais/toxicidade , Chumbo/toxicidade , Células Intersticiais do Testículo/efeitos dos fármacos , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Masculino , Camundongos
14.
Physiol Mol Biol Plants ; 27(9): 1919-1931, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34616114

RESUMO

Fructokinase (FRK) is the main fructose phosphorylase and plays an important role in catalyzing the irreversible reaction of free fructose phosphorylation. In order to study the regulatory effect of different forms and concentrations of nitrogen on PtFRK genes in Populus trichocarpa, seven genes encoding the hypothetical FRK proteins were identified in Populus trichocarpa genome by bioinformatics method. Phylogenetic analysis revealed that PtFRK family genes can be divided into two subgroups: SI (PtFRK 1, 3, 4, 6) and SII (PtFRK 2, 5, 7). The tissue-specific expression data obtained from PopGenIE indicate that PtFRK2, 3, 4 and 5 are expressed highly in the stem. Quantitative real-time RT-PCR illustrate that PtFRK1-7 showed different expression patterns in different tissues under different concentrations and morphological nitrogen application. Under high nitrate treatment, the expression levels of PtFRK1, 2, 3 and 6 in stem increased significantly, while under low nitrate treatment, only the expression of PtFRK1, 4 in the upper stem and the expression of PtFRK3, 5 in the lower stem increased significantly. In contrast, ammonium tends to inhibit the expression of PtFRKs in lower stems, the expression levels of PtFRK2, 3, 4 and 5 are significantly reduced under ammonium treatment. However, high ammonium had significant effects on PtFRK6 in the apical bud and upper leaves, which were 6 and 8 times of the control, respectively. These results laid the foundation for the study of the PtFRK gene family of poplar and provided a theoretical basis for the molecular mechanism of nitrogen regulating cell wall development. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01055-6.

15.
Angew Chem Int Ed Engl ; 60(35): 19324-19330, 2021 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-34184379

RESUMO

Semi-hydrogenation of acetylene to ethylene is an important process to purify ethylene streams in industry. However, among current approaches reported in the literature, high ethylene selectivity has been generally achieved at the expense of activity. Herein, we show that a Ga2 O3 coating of Ag@Pd core-shell bimetallic nanoparticle catalysts, allows improvement of the ethylene selectivity to a much greater extent than the coating of monometallic Pd nanoparticles, while preserving a remarkable intrinsic activity, approximately 50 times higher than the benchmark catalyst of Pd1 Ag single-atom alloys (SAAs). Importantly, the resulting catalyst also shows excellent long-term stability, by suppressing coke formation efficiently. Spectroscopic characterization reveals that weakened ethylene adsorption by bimetallic electronic synergy, and oxide site isolation are both essential for the high ethylene selectivity and high-coking resistance. H-D exchange measurements further show that the Ga2 O3 -coated Ag@Pd catalyst possesses a much higher activity of H2 activation than that of Pd1 Ag SAAs, thus boosting the hydrogenation activity at the same time.

16.
Small ; 16(52): e2005571, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33258310

RESUMO

Planar metal clusters possess high metal utilization, distinct electronic properties, and catalytic functions from their 3D counterparts. However, synthesis of these materials is challenging due to much elevated surface free energies. Here it is reported that silica supported planar bilayer Pt-CoOx subnano clusters, consisting of approximately one atomic layer of Pt and one CoOx layer on top, can be achieved by employing strong-electrostatic interactions during impregnation and precisely-controlled CoOx coating using atomic layer deposition. Such bilayer structure is unambiguously confirmed by electron microscopy and in situ X-ray absorption fine spectroscopy which is never reported before. This synthetic approach can be extended to another eight permutations of planar metal-oxide subnano clusters. The resulting bilayer catalysts, owing to unique electronic properties and the abundant metal-oxide interfaces created, exhibit excellent catalytic performances in the reactions of preferential oxidation of CO in H2 and selective hydrogenation of acetylene, by showing much higher selectivity and intrinsic activities at least 8 and 48 times greater than those conventional oxide coated 3D metal clusters/nanoparticles, highlighting the advances of bilayer interfacial structure. These findings open a new avenue to design abundant and highly active metal-oxide interfaces for advanced metal catalysis.

17.
Fish Shellfish Immunol ; 98: 632-640, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31669281

RESUMO

In this study, a Streptomyces strain was isolated from the soil samples of Yanghu Wetland Park in Changsha, Hunan Province. This strain showed excellent antimicrobial activity against 10 fish pathogens, as indicated by the results of the agar-diffusion and oxford cup assays. After 16s rDNA sequencing and physiological & biochemical analyses, it was identified as Streptomyces amritsarensis, namely for S. amritsarensis N1-32. Cytotoxicity test was performed, and the results exhibited that this strain had no toxicity to hepatic L8824 cell line from grass carp liver. The diets supplemented strain N1-32 at concentrations of 1 × 107 cfu/g and 1 × 109 cfu/g was used to feed fish. After 28 days, the expression levels of antioxidant-related genes Nrf2 and Keap1 in the liver and spleen were significantly up-regulated, and the expression of immune-related gene IgM was notably increased in the liver, kidney, head-kidney, and spleen. Toll-like receptor 4 (TLR4) gene expression was up-regulated in the spleen, and TLR4, myeloid differentiation factor 88 (MyD88) gene were up-regulated in the kidney. The survival rate of grass carp was significantly improved after pathogen infection. Whole-genome analysis of N1-32 showed that the strain harbored related genes, capability for producing substances that enhance the immunity of grass carp and inhibit pathogens. A total of 22 gene clusters were identified in the genome, including 5 terpene gene clusters, 4 nonribosomal peptide-synthetase (NRPS) gene clusters and 2 lantipeptide gene clusters. In summary, these results showed that strain N1-32 as a feed additive could regulate grass carp immunity and enhance the resistance of grass carp against fish pathogens.


Assuntos
Antibacterianos/farmacologia , Antioxidantes/metabolismo , Bactérias/efeitos dos fármacos , Expressão Gênica , Imunidade Humoral , Probióticos/farmacologia , Streptomyces/química , Ração Animal/análise , Dieta/veterinária , Expressão Gênica/efeitos dos fármacos , Genoma Bacteriano , Imunidade Humoral/efeitos dos fármacos , Probióticos/administração & dosagem , Streptomyces/genética
18.
BMC Plant Biol ; 19(1): 279, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31242858

RESUMO

BACKGROUND: Seed germination, a complex, physiological-morphogenetic process, is a critical stage in the life cycle of plants. Biological changes in germinating seeds have not been investigated in poplar, a model woody plant. RESULTS: In this study, we exploited next-generation sequencing and metabolomics analysis and uncovered a series of significantly different genes and metabolites at various stages of seed germination and post germination. The K-means method was used to identify multiple transcription factors, including AP2/EREBP, DOF, and YABBY, involved in specific seed germination and post-germination stages. A weighted gene coexpression network analysis revealed that cell wall, amino acid metabolism, and transport-related pathways were significantly enriched during stages 3 and 5, with no significant enrichment observed in primary metabolic processes such as glycolysis and the tricarboxylic acid cycle. A metabolomics analysis detected significant changes in intermediate metabolites in these primary metabolic processes, while a targeted correlation network analysis identified the gene family members most relevant to these changing metabolites. CONCLUSIONS: Taken together, our results provide important insights into the molecular networks underlying poplar seed germination and post-germination processes. The targeted correlation network analysis approach developed in this study can be applied to search for key candidate genes in specific biochemical reactions and represents a new strategy for joint multiomics analyses.


Assuntos
Germinação , Proteínas de Plantas/genética , Populus/genética , Sementes/crescimento & desenvolvimento , Fatores de Transcrição/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Germinação/genética , Proteínas de Plantas/metabolismo , Populus/crescimento & desenvolvimento , Sementes/genética , Fatores de Transcrição/metabolismo
19.
Appl Microbiol Biotechnol ; 103(21-22): 8987-8999, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31637491

RESUMO

This study evaluated the inhibition and interaction of Bacillus velezensis BvL03 as a probiotic agent against Aeromonas hydrophila. Strain BvL03 isolated from sediment samples of fish ponds had excellent antimicrobial activity against several fish pathogenic bacteria, especially Aeromonas, including A. hydrophila, A. veronii, A. caviae, and A. sobria. The successful amplification of lipopeptide antimicrobial chemical biosynthetic genes, including iturin family (ituA, ituB, and ituD), bacillomycin family (bacA, bacD, and bacAB), surfactin family (srfAB, srfC, and srfAA), and subtilosin family (albF and sunT) from the genome of BvL03 strain, confirmed its predominant antimicrobial activity. The challenge test suggested that BvL03 significantly decreased fish mortality when challenged with A. hydrophila, which had a cumulative mortality of 12.5% in the treatment group. Toxicity and hemolytic activity of A. hydrophila after co-cultured with BvL03 were relieved as confirmed by the cell experiments, when the initial inoculated concentration of BvL03 was 109 cfu/mL or higher. Moreover, the BvL03 strain labeled with GFP protein (BvL03-GFP) and AhX040 strain labeled with mCherry protein (AhX040-mCherry) were injected into grass carps. The fluorescence levels were monitored by using In Vivo Imaging System (IVIS), in which the green color was steadily increasing, whereas the red color was gradually weakening. Whole genome sequencing revealed that strain BvL03 possesses 15 gene clusters related to antibacterial compounds, including 5 NRPS gene clusters and 3 PKS gene clusters. These results suggested that B. velezensis BvL03 has the potential to be developed as a probiotic candidate against A. hydrophila infection in aquaculture.


Assuntos
Aeromonas hydrophila/fisiologia , Antibiose/fisiologia , Bacillus/fisiologia , Agentes de Controle Biológico/metabolismo , Carpas/microbiologia , Doenças dos Peixes/microbiologia , Animais , Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Catiônicos Antimicrobianos/metabolismo , Bacteriocinas/genética , Bacteriocinas/metabolismo , Doenças dos Peixes/prevenção & controle , Lipopeptídeos/genética , Lipopeptídeos/metabolismo , Peptídeos Cíclicos/genética , Peptídeos Cíclicos/metabolismo , Probióticos , Sequenciamento Completo do Genoma
20.
Int J Food Sci Nutr ; 70(5): 570-578, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30624124

RESUMO

Sulforaphane (SFN) is the major component extracted from broccoli/broccoli sprouts. It has been shown to possess anti-cancer activity. Gastric cancer is common cancer worldwide. The objective of this work was to evaluate the inhibitory effect of SFN on gastric cancer by Sonic hedgehog (Hh) Pathway. The results found that tumorsphere formation and the expression levels of gastric cancer stem cells (CSCs) markers were significantly decreased after SFN treatment. SFN also exerted inhibitory effects by suppressing proliferation and inducing apoptosis in gastric CSCs. Intriguingly, SFN inhibited the activation of Sonic Hh, a key pathway in maintaining the stemness of gastric CSCs. Upregulation of Sonic Hh pathway diminished the inhibitory effects of SFN on gastric CSCs. Collectively, these data revealed that SFN could be a potent natural compound targeting gastric CSCs via suppression of Sonic Hh pathway, which might be an promising agent for gastric cancer intervention.


Assuntos
Antineoplásicos/farmacologia , Proteínas Hedgehog/metabolismo , Isotiocianatos/farmacologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Neoplasias Gástricas/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Brassica/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica , Humanos , Receptores de Hialuronatos , Camundongos , Camundongos Transgênicos , Sulfóxidos , Regulação para Cima
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA