Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Rev Sci Instrum ; 87(2): 02B510, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26932063

RESUMO

The present paper summarizes the results obtained from the past few years in the framework of the Enhanced Multi-Ionization of short-Lived Isotopes for Eurisol (EMILIE) project. The EMILIE project aims at improving the charge breeding techniques with both Electron Cyclotron Resonance Ion Sources (ECRIS) and Electron Beam Ion Sources (EBISs) for European Radioactive Ion Beam (RIB) facilities. Within EMILIE, an original technique for debunching the beam from EBIS charge breeders is being developed, for making an optimal use of the capabilities of CW post-accelerators of the future facilities. Such a debunching technique should eventually resolve duty cycle and time structure issues which presently complicate the data-acquisition of experiments. The results of the first tests of this technique are reported here. In comparison with charge breeding with an EBIS, the ECRIS technique had lower performance in efficiency and attainable charge state for metallic ion beams and also suffered from issues related to beam contamination. In recent years, improvements have been made which significantly reduce the differences between the two techniques, making ECRIS charge breeding more attractive especially for CW machines producing intense beams. Upgraded versions of the Phoenix charge breeder, originally developed by LPSC, will be used at SPES and GANIL/SPIRAL. These two charge breeders have benefited from studies undertaken within EMILIE, which are also briefly summarized here.

2.
Rev Sci Instrum ; 85(2): 02B917, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24593622

RESUMO

Radioactive Ion Beams play an increasingly important role in several European research facility programs such as SPES, SPIRAL1 Upgrade, and SPIRAL2, but even more for those such as EURISOL. Although remarkable advances of ECRIS charge breeders (CBs) have been achieved, further studies are needed to gain insight on the physics of the charge breeding process. The fundamental plasma processes of charge breeders are studied in the frame of the European collaboration project, EMILIE, for optimizing the charge breeding. Important information on the charge breeding can be obtained by conducting similar experiments using the gas mixing and 2-frequency heating techniques with a conventional JYFL 14 GHz ECRIS and the LPSC-PHOENIX charge breeder. The first experiments were carried out with noble gases and they revealed, for example, that the effects of the gas mixing and 2-frequency heating on the production of high charge states appear to be additive for the conventional ECRIS. The results also indicate that at least in the case of noble gases the differences between the conventional ECRIS and the charge breeder cause only minor impact on the production efficiency of ion beams.

3.
Nucl Med Rev Cent East Eur ; 15(2): 163-4, 2012 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-22936515

RESUMO

Two important events happened at the Heavy Ion Laboratory of the University of Warsaw in May this year. First, on May 15 the new Radiopharmaceuticals Production and Research Centre (RPRC) was inaugurated by the Rector Elect, Prof. Marcin Palys. The construction of this Centre, located on the premises of the Laboratory, was supported by grants from the Ministry of Sciences, International Atomic Energy Agency, Ministry of Health and European Structural Funds.


Assuntos
Íons Pesados , Laboratórios/estatística & dados numéricos , Compostos Radiofarmacêuticos , Pesquisa , Universidades/estatística & dados numéricos , Polônia
4.
Rev Sci Instrum ; 83(2): 02A906, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22380247

RESUMO

As the most ambitious concept of isotope separation on line (ISOL) facility, EURISOL aims at producing unprecedented intensities of post-accelerated radioactive isotopes. Charge breeding, which transforms the charge state of radioactive beams from 1+ to an n+ charge state prior to post-acceleration, is a key technology which has to overcome the following challenges: high charge states for high energies, efficiency, rapidity and purity. On the roadmap to EURISOL, a dedicated R&D is being undertaken to push forward the frontiers of the present state-of-the-art techniques which use either electron cyclotron resonance or electron beam ion sources. We describe here the guidelines of this R&D.

5.
Appl Radiat Isot ; 67(3): 447-53, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18676154

RESUMO

Chinese hamster ovary CHO-K1 cells were exposed to high LET (12)C-beam (LET: 830 keV/microm) in the dose range of 0-6 Gy and to (60)Co irradiation and the RBE value was obtained. Effects of (12)C-beam exposure on cell survival and chromosomal aberrations were calculated. The chromosomal aberration data were fitted with linear equation. The distribution of aberration in cells was examined with a standard u-test and used to evaluate the data according to Poisson probabilities. The variance to the mean ratio sigma(2)/Y and the dispersion index (u) were determined. Overdispersion was significant (p<0.05) when the value of u exceeded 1.96.


Assuntos
Radioisótopos de Carbono , Sobrevivência Celular/efeitos da radiação , Aberrações Cromossômicas/efeitos da radiação , Animais , Células CHO/efeitos da radiação , Cricetinae , Cricetulus , Íons , Distribuição de Poisson , Radiação
6.
Meat Sci ; 80(4): 1264-72, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22063867

RESUMO

This study investigated the effect of marinades in improving the eating quality in ready-to-eat boar meat. Neck chops with fat content below 18.9%, skatole ⩽1.1ppm (range 0.03-1.1) and androstenone ⩽5.6ppm (range 0.01-5.6) were used. In a screening experiment different marinades were tested for their ability to mask boar taint (defined as manure and urine odour and flavour). Liquid smoke and oregano extracts appeared to have the best potential for masking, and were studied in detail. Results from the study indicated that marinated chops with skatole content of approximately 0.4ppm appeared similar to castrates in boar taint. Chops with skatole contents above 0.7ppm remained unmasked despite the use of strongly flavoured marinades. Unmarinated chops served at 60°C were more tainted than those served at 15°C, but scored lower for boar taint when reheated, although the concentrations of androstenone and skatole remained the same. The fat content of the chops was not well correlated to the perception of boar taint. The attributes manure and urine were correlated with the level of skatole, but urine attribute was not a good indicator of the androstenone level.

7.
Radiat Prot Dosimetry ; 122(1-4): 207-9, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17169947

RESUMO

A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw University. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as in the region of the Bragg peak.


Assuntos
Técnicas de Cultura de Células/instrumentação , Fenômenos Fisiológicos Celulares/efeitos da radiação , Ciclotrons/instrumentação , Íons Pesados , Aceleradores de Partículas/instrumentação , Radiobiologia/instrumentação , Técnicas de Cultura de Células/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Polônia , Doses de Radiação , Radiobiologia/métodos , Espalhamento de Radiação
8.
J Nat Prod ; 62(8): 1179-81, 1999 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10479333

RESUMO

Phytochemical investigation of the leaves of Paullinia pinnata L. (Sapindaceae) resulted in the isolation of the two new flavone glycosides characterized as diosmetin-7-O-(2' '-O-beta-D-apiofuranosyl-6' '-acetyl-beta-D-glucopyranoside) (1) and tricetin-4'-O-methyl-7-O-(2' '-O-beta-D-apiofuranosyl-6' '-acetyl-beta-D-glucopyranoside) (2).

9.
Tree Physiol ; 13(1): 17-27, 1993 07.
Artigo em Inglês | MEDLINE | ID: mdl-14969898

RESUMO

Changes in net carbon assimilation and water status were studied during leaf development in the deciduous, tropical species Brachystegia spiciformis Benth. In this upland savanna African tree, bud-burst and leaf development occur approximately two months before the rainy season. The newly formed leaves synthesize anthocyanin until the fully expanded leaves of the whole canopy are red. This foliage is referred to as "spring flush" foliage. Subsequently, the anthocyanins are metabolized and the pre-rain leaves become green. Carbon dioxide assimilation exhibited a bimodal diurnal pattern and was similar for pre-rain green leaves and fully expanded flushing leaves, although pre-rain green leaves showed a net uptake of carbon throughout the daylight period, whereas flushing leaves exhibited only brief periods of net photosynthesis in the morning and early afternoon. Measurements of leaf water potential and relative water content showed a diurnal pattern with considerable variation throughout the day. Leaf water potential and relative water content values decreased soon after sunrise reaching a minimum at a time corresponding to the afternoon peak in CO(2) assimilation. Stomatal conductance was closely related to transpiration rate in both flushing and pre-rain green leaves, although flushing leaves had lower stomatal conductances than pre-rain green leaves. Pre-rain green leaves exhibited a compensation irradiance of approximately 180 micro mol m(-2) s(-1), whereas flushing leaves had positive net photosynthesis only at PPFDs greater than 300 micro mol m(-2) s(-1). Rate of photosynthesis (expressed per leaf area or chlorophyll unit) increased as anthocyanin concentration decreased, although the photosynthetic rate continued to increase long after the leaf anthocyanins had been degraded to low, visually undetectable amounts. Post-rain green leaves had chlorophyll concentrations, transpiration rates and stomatal conductances similar to those of pre-rain green leaves; however, photosynthetic rates in post-rain leaves were more than three times higher. Thus, during the early stages of the spring flush, carbon asimilation rates of the flushing leaves were inversely related to leaf anthocyanin concentrations. In pre-rain green leaves, photosynthesis was limited by other non-stomatal factors.

10.
Planta ; 152(5): 428-35, 1981 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24301116

RESUMO

Cotton (Gossypium hirsutum L.) embryos excised from bolls 38-43 d after anthesis and cultured in vitro for 4 d on a nutrient agar medium containing 3.8 µM abscisic acid (ABA) developed enzyme activity and accumulated insoluble protein, neutral lipid, and dry weight similar to embryos maturing on the plant. Inclusion of ABA in the medium prevented precosious germination and allowed continued increases in catalase, malate dehydrogenase, citrate synthase, aspartate aminotransferase, and ß-oxidation enzyme activities as well as de-novo synthesis of malate synthase. Isocitrate lyase activity was not detectable in ABA-cultured embryos nor normally-developed embryos. Omission of sucrose from the medium resulted in near-doubling of the development of malate synthase activity, with minimal effects on the other enzyme activities. Addition of Actinomycin D, cordycepin, or cycloheximide to ABA-containing cultures did not overcome the observed inhibition of germination, but severely reduced both the appearance of new malate synthase activity and further production of other related enzyme activities. Thus, development of these enzyme activities in the presence of ABA appears dependent on transcription and translation, while inhibition of germination by ABA at this stage of development is not sensitive to the RNA- and protein-synthesis inhibitors. The results indicate that ABA does not prevent vivipary by suppressing translation of m-RNAs coding for isocitrate lyase and its companion enzymes, as previously proposed.

11.
Plant Physiol ; 65(6): 1031-5, 1980 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16661324

RESUMO

Treatment of etiolated pea (Pisum sativum (L. cv. Alaska) seedlings with 2'-isopropyl-4'-(trimethylammonium chloride)-5'-methylphenyl piperidine-1-carboxylate (Amo-1618) prior to irradiation with white light inhibits photomorphogenesis and formation and stacking of thylakoid membranes in the chloroplasts, as well as (-)-kaur-16-ene (ent-kaurene)biosynthesis. Exogenous gibberellic acid also inhibits greening. A crudely determined action spectrum for the photoinduction of ent-kaurene biosynthesis shows two peaks, one in the blue region at 458 to 490 nanometers and another in the red region at 606 to 678 nanometers. The possible participation of phytochrome in the photoinduction of ent-kaurene biosynthesis is indicated by comparative effects of red, far red, and alternating red/far red irradiations on enhancement of enzyme activity. The activity of blue light as well as red shows a similarity of the photoinduction of ent-kaurene synthesis activity to the high irradiance responses, and indicates probable participation of a second photoreceptor. From these observations, it is concluded that photoinduction of ent-kaurene biosynthesis and chloroplast development in shoots are closely linked processes.

12.
Plant Physiol ; 63(6): 1068-71, 1979 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16660858

RESUMO

Extracts from several species and varieties of ungerminated cotton seeds plus homogenates from 18 other oilseeds (representing 11 different families) were examined for malate synthase and isocitrate lyase activity. Malate synthase activities in the various cotton seeds ranged from 35 to 129% of the units per dry seed weight found in Deltapine 16 cotton. For other oilseeds, the range was from 0.3 to 58% of Deltapine 16 cotton. Castor bean (Ricinus communis L.) had the least activity per mg dry weight (12-fold lower than the next lowest species), while Pima cotton (Gossypium barbadense L.) had the highest level (8.53 units). On a per seed basis, these values were 15 and 747 nanomoles per minute.Malate synthase activity was measurable in all seed types examined, whereas isocitrate lyase could not be detected in any of the seeds. We suggest that synthesis of malate synthase during seed development is universal among oilseeds in the absence of glyoxylate-cycle-associated isocitrate lyase activity.

13.
Plant Physiol ; 62(1): 141-5, 1978 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16660455

RESUMO

The sequence of glyoxysomal enzyme development was investigated in cotyledons of cotton (Gossypium hirsutum L. cv. Deltapine 16) embryos from 16 to 70 days after anthesis (DAA). Catalase, malate dehydrogenase, and citrate condensing enzyme activities were barely detectable prior to 22 DAA, but showed dramatic increases from 22 to 50 DAA. Development of malate synthase activity, however, was delayed during this period, rising to peak activity from 45 to 50 DAA (just prior to desiccation) in the absence of any detectable isocitrate lyase activity. Substantial activities of all of these enzymes (except isocitrate lyase) persisted in the dry seeds. Isopycnic centrifugations on sucrose gradients demonstrated that the enzymes were compartmentalized within particles increasing in buoyant density with time of development (1.226 to 1.245 grams per cubic centimeter from 22 to 50 DAA). Of particular significance were the observations in 22-day embryos of smooth surfaced membrane dilations of rough endoplasmic reticulum having cytochemical catalase reactivity, and the demonstrations of catalase activities in microsomal fractions isolated throughout the 16- to 50-DAA period. Our data do not allow determination of the mechanism(s) for enzyme activation and/or addition to previously existing or newly formed microbodies, but do show that development and acquisition of enzyme activities within glyoxysomes occur sequentially and thus are not regulated in concert as previously thought.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...