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1.
J Hazard Mater ; 423(Pt B): 127056, 2022 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-34547692

RESUMEN

Reducing the cost of pellet additives as a substitute for reducing bentonite binder is an important research direction of new pellet additives. There are some industrial solid wastes that have the similar physical and chemical properties to bentonite, and SiO2 content of them may be much lower than bentonite, but also contains a lot of Fe2O3, Al2O3, MgO, B2O3 and other components beneficial to the quality of pellets, which have been paid more attention by many pellet workers. In this review, the effect mechanism of Fe2O3, Na2O/K2O, Al2O3, SiO2, CaO, MgO and B2O3 in the industrial solid wastes on the fired strength and reduction expansion of pellets were systematically summarized. At the same time, the influences of five representative large scale modified industrial solid waste additives including iron tailings, bauxite tailings, fly ash, red mud and boron sludge on the properties of green pellets and finished pellets were described in detail. It can be seen that the applications of industrial solid waste in pellet additives can partially or completely replace bentonite binder, especially fly ash, red mud and boron sludge, which can not only improve the quality of pellets, but also decrease the cost, save energy and reduce pollution, with significant economic benefits.

2.
Ying Yong Sheng Tai Xue Bao ; 32(9): 3097-3106, 2021 Sep.
Artículo en Chino | MEDLINE | ID: mdl-34658194

RESUMEN

To investigate the interaction between Pinus tabuliformis and root microorganisms and its effects on the stability of P. tabuliformis forests, we collected rhizosphere and non-rhizosphere soil from natural and planted P. tabuliformis forests in Huanglong County of Shaanxi Province. The non-rhizosphere soil was used to analyze chemical properties, while the rhizosphere soil was used to isolate and purify phosphorus-solubilizing (organic and inorganic phosphorus) bacteria. We mea-sured the phosphate-solubilizing ability and identified those bacteria using DNA genes sequencing. The results showed that soil total carbon concentration (TC), total nitrogen concentration (TN), carbon:nitrogen (C/N), and nitrogen:phosphorus (N/P) were significantly higher in natural forest than those in the plantation. A total of 20 genera and 65 species of phosphate-solubilizing bacteria were identified in those two forests, with Bacillus, Streptomyces and Pseudomonas as the dominant group. The diversity, richness, and evenness of phosphate-solubilizing bacteria in the natural forest were higher than that in the planted forest, but dominance was lower. Streptomyces was positively correlated with soil TC, TN, C/N and N/P ratios, while Bacillus and Pseudomonas were positively correlated with soil nitrate (NO3-), ammonium (NH4+), available phosphorus (AP), and total phosphorus (TP). The solubilizing ability of phosphate-solubilizing bacteria was different between two forest types, indicating that Pseudomonas sp.34-5 shared in two forests had the strongest phosphate-solubilizing ability for calcium phosphate with 11.40 µg·mL-1 and Bacillus mycoides BF1-5 exclusive to natural forest had the strongest phosphate-solubilizing ability for lecithin with 4.58 µg·mL-1. The composition and structure of phosphorus-solubilizing bacterial community were different in two forest types, with higher diversity, richness and phosphate-solubilizing ability in natural forest than that in plantation.


Asunto(s)
Pinus , Rizosfera , Bacillus , Bacterias/genética , China , Bosques , Fosfatos , Suelo , Microbiología del Suelo
3.
Rev Sci Instrum ; 92(9): 094703, 2021 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-34598530

RESUMEN

In circular waveguides, the TE01 mode has the lowest transmission loss, which is very suitable for long-distance transmission of high-power microwaves (HPMs). The output mode of HPM sources is mainly the TM01 mode; however, there are few research studies on mode converters of TM01-TE01. In this paper, a high efficiency HPM TM01-TE01 mode converter is designed; compared with the traditional TM01-TE01 mode converters, the structure of the mode converter is compact and easier to process. It is mainly composed of an input circular waveguide, a tapered rectangular waveguide, a 90° bent rectangular waveguide, and an output circular waveguide. A prototype with a center frequency of 2.4 GHz is fabricated and HPM experiments are carried out. The transmission efficiency of this device reaches 99.8% in the simulation, and the measured transmission efficiency is more than 98%. Additionally, the measured power handling capacity is more than 1 GW, which is consistent with simulation. This design has important reference significance for the design of long-distance power transmission devices and HPM mode converters.

4.
Rev Sci Instrum ; 92(8): 084709, 2021 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-34470405

RESUMEN

A compact double-layer wideband 1:60 power divider/combiner based on a radial-line waveguide is designed and investigated for high-power microwave (HPM) applications. Compared with other HPM radial-line power dividers, the proposed power divider is smaller and more compact. The power divider is miniaturized by the double-layer method, and the wideband characteristic is realized by a specially designed wavy disk. Moreover, it can divide the microwave energy into 60 output ports equally by symmetrical design. As for simulation, in the range of 1.64-3.6 GHz, the voltage standing-wave ratio is below 2 (the relative bandwidth is 76%) and the return loss reaches -44 dB at 2.1 GHz. Additionally, a prototype is fabricated and the wideband performance from 1.6 to 2.6 GHz is verified by an existing wideband antenna array. Furthermore, filled with SF6 (0.3 MPa), the theoretical power handling capacity is more than 200 MW and the device works steadily in HPM tests under the condition of 140 MW. To sum up, the compact power divider/combiner has important application potentials in HPM fields.

6.
Mitochondrial DNA B Resour ; 3(1): 145-146, 2018 Jan 26.
Artículo en Inglés | MEDLINE | ID: mdl-33474100

RESUMEN

Tricyrtis (Liliaceae) is an endemic genus in East Asia. Many of the species in the genus are in Endangered condition due to habitat loss and extensive horticultural usage in recent decades. In present study, we reported the first Tricyrtis chloroplast (cp) genome, Tricyrtis macropoda, based on Illumina pair-end sequencing data. The complete chloroplast genome size is 155,778 bp. In total, 131 genes were identified, including 85 protein-coding genes, 8 rRNA genes, and 38 tRNA genes. Fifteen genes are containing introns (clpP and ycf3 contained two introns) and 14 genes had two copies. The overall GC content of this genome was 37.4%. A further phylogenomic analysis of Liliales, including 62 taxa, was conducted for the placement of genus Tricyrtis. The complete plastome of T. marcropoda will provide a valuable resource for further genetic conservation, phylogenomic, and evolution studies in the genus and family.

7.
Mitochondrial DNA B Resour ; 3(2): 1081-1082, 2018 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-33490560

RESUMEN

Linnaea chinensis (Caprifoliaceae), which inhabits in China and Japan, is commonly cultivated as an ornamental shrub. The complete chloroplast genome of L. chinensis was newly assembled in this study based on Illumina pair-end sequencing data. The full length of L. chinensis plastome is 155,813 bp. In total, 124 genes were identified, including 75 protein-coding genes, 8 rRNA genes, and 42 tRNA genes. The overall GC content of this genome was 38.4%. A further phylogenomic analysis including16 species from Adoxaceae and Caprifoliaceae was constructed.

8.
Zhongguo Zhong Yao Za Zhi ; 42(17): 3312-3319, 2017 Sep.
Artículo en Chino | MEDLINE | ID: mdl-29192440

RESUMEN

With Sophora japonica at the flowering stage as the object, the effect of nitrogen, phosphorus and potassium fertilizers on the yield composition factors, yield and quality of Flos Sophorae Immaturus (FSI) was studied. The results indicated that in early spring, nitrogen, phosphorus and potassium fertilizer on the amplification rate of S. japonica, FSI yield composition, yield and quality were different significantly, middle to high nitrogen (1.5-2.0 kg/plant) significantly increased the level of panicled clusters, raceme and flower bud number and yield. Phosphorus (1.5-2.0 kg/plant) could significantly increase the total buds of flower number and yield, potassium showed no significant increase in yield and yield components. Comprehensively considering yield and quality of FSI, nitrogen 1.5-2.0 kg/plant, phosphorus 1.5-2.0 kg/plant and potassium 0.6-0.9 kg/plant are appropriate.


Asunto(s)
Fertilizantes , Flores/crecimiento & desarrollo , Nitrógeno , Fósforo , Potasio , Sophora/crecimiento & desarrollo , China , Plantas Medicinales/crecimiento & desarrollo
9.
Sensors (Basel) ; 17(10)2017 Oct 13.
Artículo en Inglés | MEDLINE | ID: mdl-29027944

RESUMEN

Silicon carbide (SiC) detectors of an Ni/4H-SiC Schottky diode structure and with sensitive areas of 1-4 cm² were fabricated using high-quality lightly doped epitaxial 4H-SiC material, and were tested in the detection of alpha particles and pulsed X-rays/UV-light. A linear energy response to alpha particles ranging from 5.157 to 5.805 MeV was obtained. The detectors were proved to have a low dark current, a good energy resolution, and a high neutron/gamma discrimination for pulsed radiation, showing the advantages in charged particle detection and neutron detection in high-temperature and high-radiation environments.

10.
Zhongguo Zhong Yao Za Zhi ; 42(5): 902-911, 2017 Mar.
Artículo en Chino | MEDLINE | ID: mdl-28994533

RESUMEN

The endophytic fungi from root, main stem, branch and leaf of Scrophularia ningpoensis were isolated and identified from Wulong and Chongqing, and the population diversity analysis and phylogenetic analysis were followed. The result indicated that, as to population diversity index, S. ningpoensis from Wulong: leaf>main stem=branch>root, branch from Chongqing>branch from Wulong. Fifty-eight endophytic fungi were obtained, most of which were the pathogens of the plant. Colletotrichum was the prevailing genus, of which C. gloeosporioides and C. boninense were the prevailing strains. Leaf and seedlings might be the main path of infection. Endophytic fungi and pathogen might convert to each other, influenced by such factors as environment, genotype et al.


Asunto(s)
Endófitos/clasificación , Hongos/clasificación , Filogenia , Scrophularia/microbiología , China , Colletotrichum , Hojas de la Planta/microbiología , Raíces de Plantas/microbiología , Tallos de la Planta/microbiología
11.
Sci Rep ; 6: 22911, 2016 Mar 18.
Artículo en Inglés | MEDLINE | ID: mdl-26987602

RESUMEN

Aim of this study was to develop a new simpler and more effective severity score for community-acquired pneumonia (CAP) patients. A total of 1640 consecutive hospitalized CAP patients in Second Affiliated Hospital of Zhejiang University were included. The effectiveness of different pneumonia severity scores to predict mortality was compared, and the performance of the new score was validated on an external cohort of 1164 patients with pneumonia admitted to a teaching hospital in Italy. Using age ≥ 65 years, LDH > 230 u/L, albumin < 3.5 g/dL, platelet count < 100 × 10(9)/L, confusion, urea > 7 mmol/L, respiratory rate ≥ 30/min, low blood pressure, we assembled a new severity score named as expanded-CURB-65. The 30-day mortality and length of stay were increased along with increased risk score. The AUCs in the prediction of 30-day mortality in the main cohort were 0.826 (95% CI, 0.807-0.844), 0.801 (95% CI, 0.781-0.820), 0.756 (95% CI, 0.735-0.777), 0.793 (95% CI, 0.773-0.813) and 0.759 (95% CI, 0.737-0.779) for the expanded-CURB-65, PSI, CURB-65, SMART-COP and A-DROP, respectively. The performance of this bedside score was confirmed in CAP patients of the validation cohort although calibration was not successful in patients with health care-associated pneumonia (HCAP). The expanded CURB-65 is objective, simpler and more accurate scoring system for evaluation of CAP severity, and the predictive efficiency was better than other score systems.


Asunto(s)
Biomarcadores/análisis , Infecciones Comunitarias Adquiridas/mortalidad , Neumonía/mortalidad , Anciano , Área Bajo la Curva , China/epidemiología , Infecciones Comunitarias Adquiridas/metabolismo , Femenino , Hospitalización , Humanos , Tiempo de Internación , Masculino , Persona de Mediana Edad , Neumonía/metabolismo , Factores de Riesgo , Índice de Severidad de la Enfermedad
12.
Molecules ; 21(3): 296, 2016 Mar 02.
Artículo en Inglés | MEDLINE | ID: mdl-26950107

RESUMEN

Microwave-assisted extraction was applied to extract rutin; quercetin; genistein; kaempferol; and isorhamnetin from Flos Sophorae Immaturus. Six independent variables; namely; solvent type; particle size; extraction frequency; liquid-to-solid ratio; microwave power; and extraction time were examined. Response surface methodology using a central composite design was employed to optimize experimental conditions (liquid-to-solid ratio; microwave power; and extraction time) based on the results of single factor tests to extract the five major components in Flos Sophorae Immaturus. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis. Data were also analyzed using appropriate statistical methods. Optimal extraction conditions were as follows: extraction solvent; 100% methanol; particle size; 100 mesh; extraction frequency; 1; liquid-to-solid ratio; 50:1; microwave power; 287 W; and extraction time; 80 s. A rapid and sensitive ultra-high performance liquid chromatography method coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (EIS-Q-TOF MS/MS) was developed and validated for the simultaneous determination of rutin; quercetin; genistein; kaempferol; and isorhamnetin in Flos Sophorae Immaturus. Chromatographic separation was accomplished on a Kinetex C18 column (100 mm × 2.1 mm; 2.6 µm) at 40 °C within 5 min. The mobile phase consisted of 0.1% aqueous formic acid and acetonitrile (71:29; v/v). Isocratic elution was carried out at a flow rate of 0.35 mL/min. The constituents of Flos Sophorae Immaturus were simultaneously identified by EIS-Q-TOF MS/MS in multiple reaction monitoring mode. During quantitative analysis; all of the calibration curves showed good linear relationships (R² > 0.999) within the tested ranges; and mean recoveries ranged from 96.0216% to 101.0601%. The precision determined through intra- and inter-day studies showed an RSD% of <2.833%. These results demonstrate that the developed method is accurate and effective and could be readily utilized for the comprehensive quality control of Flos Sophorae Immaturus.


Asunto(s)
Sophora/química , Cromatografía Líquida de Alta Presión , Genisteína/aislamiento & purificación , Quempferoles/aislamiento & purificación , Medicina Tradicional China , Microondas , Plantas Medicinales/química , Quercetina/análogos & derivados , Quercetina/aislamiento & purificación , Rutina/aislamiento & purificación , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masas en Tándem
13.
Int J Biol Macromol ; 76: 80-5, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25732619

RESUMEN

High-pressure ultrasound-assisted extraction was used to extract polysaccharides from the Ligusticum chuanxiong rhizomes. Three independent variables, namely, extraction temperature (X1), ultrasonic power (X2) and extraction time (X3) were investigated. Response surface methodology was performed based on the results of single-factor tests. Experimental data were fitted to a second-order polynomial equation using multiple regression analysis, and results were examined using appropriate statistical methods. The optimal conditions were as follows: extraction temperature of 85°C, ultrasonic power of 187 W and extraction time of 29 min. Under these conditions, the experimental yield of polysaccharides was 5.33%, which is close to the predicted yield of 5.41%. The extracted and purified polysaccharides showed excellent antioxidative effects on 2,2-diphenyl-1-picryl-hydrazy, hydroxyl and superoxide radicals in vitro.


Asunto(s)
Antioxidantes/farmacología , Fraccionamiento Químico/métodos , Ligusticum/química , Extractos Vegetales/farmacología , Polisacáridos/farmacología , Presión , Rizoma/química , Ondas Ultrasónicas , Antioxidantes/química , Antioxidantes/aislamiento & purificación , Radicales Libres/antagonistas & inhibidores , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Polisacáridos/química , Polisacáridos/aislamiento & purificación , Reproducibilidad de los Resultados
14.
Mol Plant Pathol ; 16(8): 847-59, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25605006

RESUMEN

The ATP-dependent Lon protease is involved in many physiological processes. In bacteria, Lon regulates pathogenesis and, in yeast, Lon protects mitochondia from oxidative damage. However, little is known about Lon in fungal phytopathogens. MAP1, a homologue of Lon in Magnaporthe oryzae, was recently identified to be important for stress resistance and pathogenesis. Here, we focus on a novel pathogenic pathway mediated by MAP1. Based on an interaction system between rice and a tandem affinity purification (TAP)-tagged MAP1 complementation strain, we identified 23 novel fungal proteins from infected leaves using a TAP approach with mass spectrometry, and confirmed that 14 of these proteins physically interact with MAP1 in vivo. Among these 14 proteins, 11 candidates, presumably localized to the mitochondria, were biochemically determined to be substrates of MAP1 hydrolysis. Deletion mutants were created and functionally analysed to further confirm the involvement of these proteins in pathogenesis. The results indicated that all mutants showed reduced conidiation and sensitivity to hydrogen peroxide. Appressorial formations were not affected, although conidia from certain mutants were morphologically altered. In addition, virulence was reduced in four mutants, enhanced (with lesions forming earlier) in two mutants and remained unchanged in one mutant. Together with the known virulence-related proteins alternative oxidase and enoyl-CoA hydratase, we propose that most of the Lon-interacting proteins are involved in the pathogenic regulation pathway mediated by MAP1 in M. oryzae. Perturbation of this pathway may represent an effective approach for the inhibition of rice blast disease.


Asunto(s)
Adenosina Trifosfato/metabolismo , Magnaporthe/enzimología , Mitocondrias/enzimología , Micosis/metabolismo , Oryza/microbiología , Proteasa La/metabolismo , Cromatografía de Afinidad , Datos de Secuencia Molecular , Micosis/enzimología , Proteasa La/aislamiento & purificación
15.
Plant Physiol ; 167(2): 394-410, 2015 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-25540331

RESUMEN

The intercellular movement of plant viruses requires both viral and host proteins. Previous studies have demonstrated that the frame-shift protein P3N-PIPO (for the protein encoded by the open reading frame [ORF] containing 5'-terminus of P3 and a +2 frame-shift ORF called Pretty Interesting Potyviridae ORF and embedded in the P3) and CYLINDRICAL INCLUSION (CI) proteins were required for potyvirus cell-to-cell movement. Here, we provide genetic evidence showing that a Tobacco vein banding mosaic virus (TVBMV; genus Potyvirus) mutant carrying a truncated PIPO domain of 58 amino acid residues could move between cells and induce systemic infection in Nicotiana benthamiana plants; mutants carrying a PIPO domain of seven, 20, or 43 amino acid residues failed to move between cells and cause systemic infection in this host plant. Interestingly, the movement-defective mutants produced progeny that eliminated the previously introduced stop codons and thus restored their systemic movement ability. We also present evidence showing that a developmentally regulated plasma membrane protein of N. benthamiana (referred to as NbDREPP) interacted with both P3N-PIPO and CI of the movement-competent TVBMV. The knockdown of NbDREPP gene expression in N. benthamiana impeded the cell-to-cell movement of TVBMV. NbDREPP was shown to colocalize with TVBMV P3N-PIPO and CI at plasmodesmata (PD) and traffic to PD via the early secretory pathway and the actomyosin motility system. We also show that myosin XI-2 is specially required for transporting NbDREPP to PD. In conclusion, NbDREPP is a key host protein within the early secretory pathway and the actomyosin motility system that interacts with two movement proteins and influences virus movement.


Asunto(s)
Actomiosina/metabolismo , Nicotiana/metabolismo , Proteínas de Plantas/metabolismo , Plasmodesmos/metabolismo , Vías Secretoras , Citoesqueleto de Actina/efectos de los fármacos , Citoesqueleto de Actina/metabolismo , Secuencia de Aminoácidos , Brefeldino A/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Silenciador del Gen/efectos de los fármacos , Proteínas Fluorescentes Verdes/metabolismo , Modelos Biológicos , Datos de Secuencia Molecular , Movimiento/efectos de los fármacos , Mutación , Miosinas/metabolismo , Enfermedades de las Plantas/virología , Plasmodesmos/efectos de los fármacos , Potyvirus/patogenicidad , Unión Proteica/efectos de los fármacos , Estructura Terciaria de Proteína , Transporte de Proteínas/efectos de los fármacos , Proteínas Recombinantes de Fusión/metabolismo , Saccharomyces cerevisiae/metabolismo , Vías Secretoras/efectos de los fármacos , Fracciones Subcelulares/efectos de los fármacos , Fracciones Subcelulares/metabolismo , Tiazolidinas/farmacología , Nicotiana/efectos de los fármacos , Proteínas Virales/química , Proteínas Virales/metabolismo
16.
Zhongguo Zhong Yao Za Zhi ; 39(9): 1650-5, 2014 May.
Artículo en Chino | MEDLINE | ID: mdl-25095378

RESUMEN

A simple and quick method is described for the determination of ferulic acid, senkyunolide I, senkyunolide H, senkyunolide A and ligustilide in rhizomes of Ligusticum chuanxiong. The 5 active ingredients in the sample was extracted using 40% ethanol and analyzed by reversed-phase high performance liquid chromatography (HPLC). Chromatography separation was performed using Agilent 1100 series HPLC system with a Symmetry C18 column and gradient elution with a mixture of three solvents : solvent A, acetonitrile, solvent B, methanol and solvent C, 1% aqueous acetic acid, 0 min to 5 min A: B: C 20: 40: 40, 5 min to 30 min A: B: C 60 to 100 : 0 : 40 to 0. The effluent was monitored using a VWD detector set at 321 nm (0-4.3 min) and 275 nm (4.31-30 min). The flow rate was set at 1 mL x min(-1) and the injection volume was 10 microL. The column temperature was maintained at 35 degrees C. The calibration curve was linear (r > or = 0.99) over the tested ranges. The average recovery was 94.44%-103.1% (n = 6). The method has been successfully applied to the analysis in different harvest periods of L. chuanxiong samples. In this paper, single-factor randomized block design to study the 5 components content of L. chuanxiong on ten collecting stages. For the L. chuanxiong collected from April 15th to May 30rd, the content of 5 ingredients increased primarily, and then decreased. Determine the appropriate harvest time has important significance to the promotion of the quality of L. chuanxiong.


Asunto(s)
4-Butirolactona/análogos & derivados , Benzofuranos/análisis , Cromatografía Líquida de Alta Presión/métodos , Ácidos Cumáricos/análisis , Ligusticum/química , 4-Butirolactona/análisis , Ácido Acético/química , Acetonitrilos/química , Metanol/química , Solventes/química , Factores de Tiempo
17.
Ying Yong Sheng Tai Xue Bao ; 25(5): 1266-74, 2014 May.
Artículo en Chino | MEDLINE | ID: mdl-25129924

RESUMEN

The black locust plantations located in Weibei area were chosen as research objects and the texture parameters of different window sizes from high resolution imagery were measured. Four different techniques, including simple linear regression model, quadratic regression model, power model and exponential model, were developed to describe the relationship between the texture parameters and field measurements of LAI and to select the most effective texture parameters and window size. The results showed that the texture parameters influenced the accuracy of LAI estimation. Angular second moment and entropy index yielded better adjust r2 than the other parameters. The r2 changed with the window size. Dissimilarity and contrast index gained the largest r2 when the window size was 9x9. The r2 of the other texture parameters reduced as the window size increased and a window size of 3 x 3 was more successful than any of the others. Power equation performed poorest than the other three techniques for estimation of LAI.


Asunto(s)
Hojas de la Planta/crecimiento & desarrollo , Robinia/crecimiento & desarrollo , Bosques , Modelos Estadísticos , Imágenes Satelitales
18.
Chem Commun (Camb) ; 50(69): 9969-72, 2014 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-25034974

RESUMEN

We report the exploration of fluorescent nanoscale metal-organic frameworks (nMOF-253s) for highly selective and sensitive detection of Fe(2+) ions in aqueous solution. Moreover, nMOF-253 of 50 nm is successfully applied in fluorescent bioimaging and intracellular Fe(2+) sensing in HeLa cells.


Asunto(s)
Cationes Bivalentes/análisis , Colorantes Fluorescentes/química , Hierro/análisis , Compuestos Organometálicos/química , Compuestos Ferrosos/análisis , Células HeLa , Humanos , Luminiscencia , Modelos Moleculares , Imagen Óptica
19.
Rev Sci Instrum ; 85(5): 053512, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24880374

RESUMEN

The improved magnetically insulated transmission line oscillator (MILO) is a gigawatt-class L-band high power microwave tube. It has allowed us to generate 3.1 GW pulse of 40 ns duration in the single-pulse operation and 500 MW pulse of 25 ns duration in the repetition rate operation. However, because of the severe impedance mismatch, the power conversion efficiency is only about 4% in the repetition rate operation. In order to eliminate the impedance mismatch and obtain repetitive long-pulse high-power microwave (HPM), a series of experiments are carried out and the recent progress is presented in this paper. In the single-pulse operation, when the diode voltage is 466 kV and current is 41.6 kA, the radiated microwave power is above 2.2 GW, the pulse duration is above 102 ns, the microwave frequency is about 1.74 GHz, and the power conversion efficiency is about 11.5%. In the repetition rate operation, under the condition of the diode voltage about 400 kV, beam current about 38 kA, the radiated microwave power is about 1.0 GW, the pulse duration is about 85 ns. Moreover, the radiated microwave power and the pulse duration decline little by little when the shot numbers increase gradually. The experimental results show that the impedance matching is a vital factor for HPM systems and one of the major technical challenges is to improve the cathode for the repetition rate operation MILO.

20.
Rev Sci Instrum ; 85(4): 044709, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24784640

RESUMEN

In this paper, the inner surface flash-over of high-voltage self-breakdown switch, which is used as a main switch of pulse modulator, is analyzed in theory by employing the method of distributed element equivalent circuit. Moreover, the field distortion of the switch is simulated by using software. The results of theoretical analysis and simulation by software show that the inner surface flash-over usually starts at the junction points among the stainless steel, insulator, and insulation gas in the switch. A switch with improved structure is designed and fabricated according to the theoretical analysis and simulation results. Several methods to avoid inner surface flash-over are used to improve the structure of switch. In experiment, the inductance of the switch is no more than 100 nH, the working voltage of the switch is about 600 kV, and the output voltage and current of the accelerator is about 500 kV and 50 kA, respectively. And the zero-to-peak rise time of output voltage at matched load is less than 30 ns due to the small inductance of switch. The original switch was broken-down after dozens of experiments, and the improved switch has been worked more than 200 times stably.

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