951 resultados para Two-phase gas-solid flow
Resumo:
The research we present here forms part of a two-phase project - one quantitative and the other qualitative - assessing the use of primary health care services. This paper presents the qualitative phase of said research, which is aimed at ascertaining the needs, beliefs, barriers to access and health practices of the immigrant population in comparison with the native population, as well as the perceptions of healthcare professionals. Moroccan and sub-Saharan were the immigrants to who the qualitative phase was specifically addressed. The aims of this paper are as follows: to analyse any possible implications of family organisation in the health practices of the immigrant population; to ascertain social practices relating to illness; to understand the significances of sexual and reproductive health practices; and to ascertain the ideas and perceptions of immigrants, local people and professionals regarding health and the health system. Methods: qualitative research based on discursive analysis. Data gathering techniques consisted of discussion groups with health system users and semi-structured individual interviews with healthcare professionals. The sample was taken from the Basic Healthcare Areas of Salt and Banyoles (belonging to the Girona Healthcare Region), the discussion groups being comprised of (a) 6 immigrant Moroccan women, (b) 7 immigrant sub-Saharan African women and (c) 6 immigrant and native population men (2 native men, 2 Moroccan men and 2 sub-Saharan men); and the semi-structured interviews being conducted with the following healthcare professionals: (a) 3 gynaecologists, (b) 3 nurses and 1 administrative staff. Results: use of the healthcare system is linked to the perception of not being well, knowledge of the healthcare system, length of time resident in Spain and interiorization of traditional Western medicine as a cure mechanism. The divergences found among the groups of immigrants, local people and healthcare professionals with regard to healthcare education, use of the healthcare service, sexual and reproductive healthcare and reticence with regard to being attended by healthcare personnel of the opposite sex demonstrate a need to work with the immigrant population as a heterogeneous group. Conclusions: the results we have obtained support the idea that feeling unwell is a psycho-social process, as it takes place within a specific socio-cultural situation and spans a range of beliefs, perceptions and ideas regarding symptomology and how to treat it
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The goal of this article is to discuss the application of comprehensive two-dimensional gas chromatography (GCxGC) to petrochemical samples. The use of GCxGC for petroleum and petroleum derivatives characterization, through group type analysis, or BTEX (benzene, toluene, ethylbenzene, xylenes), total aromatic hydrocarbons, polyaromatic hydrocarbons, sulfur-containing, oxygen-containing, and nitrogen-containing compounds is presented. The capability of GCxGC to provide additional specific chemical information regarding petroleum processing steps, such as dehydrogenation of linear alkanes, the Fischer-Tropsch process, hydrogenation and oligomerization is also described. In addition, GCxGC analyses of petrochemical biomarkers and environmental pollutants derived from petrochemicals are reported.
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By the year 2005 the world biochemical market will reach an estimated $ 100 billion and separation processes are a vital link between lab discoveries and the fulfillment of this commercialization potential. The practical application of aqueous two-phase systems (ATPS) to extraction processes has been exploited for several years for the recovery of biological products. Unfortunately, this has not resulted in an extensive presence of the technique in commercial processes. In this paper a critical overview of the fundamental thermodynamic properties related to formation of aqueous two-phase systems and their application to extraction and purification of bioparticules is presented.
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Comprehensive Multidimensional Chromatography is a relatively new analytic technique, which is receiving growing attention in many parts of the world, including recently in Brazil. This work presents terms in Portuguese which are commonly used in Comprehensive Multidimensional Chromatography in order to help standardize the vocabulary employed in this area in the scientific literature. It also includes some symbols, their nominations, and explanation of some terms, whenever necessary. This proposal does not intend to be comprehensive or definitive; on the contrary, it intends to be a first step in the process of establishing a standardized nomenclature, serving as a base for a further sound discussion in the scientific community realm.
Resumo:
The essential oils from leaves (sample A) and flowers (sample B) of Aeolanthus suaveolens Mart. ex Spreng were obtained by hydrodistillation and analyzed by GC, GC-MS, and chiral phase gas chromatography (CPGC). Six compounds have been identified from the essential oils, representing ca 94.3 and 93% of the oils corresponding to samples A and B, respectively. The major constituents of samples A and B essential oils were respectively, linalool (34.2%/34.9%), (-)-massoialactone (25.9%/17.0%) and (E)-beta-farnesene (25.4%/29.1%). The enantiomeric distribution of the monoterpene linalool was established by analysis on heptakis- (6-O-methyl-2,3-di-O-pentyl)-beta-cyclodextrin capillary column. The antimicrobial activity of the essential oil from leaves and isolated compounds was also evaluated.
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Tämän työn tavoitteena oli kehittää monitehdasympäristöön siirtyneen pk-yrityksen tuotannon tuotetiedonhallintaa. Hajautettu tuotanto ja verkostoituminen oli luonut uusia haasteita ja vaatimuksia tuotetiedonhallinnalle. Teoriaosassa selvitettiin mitä tuotannon tuotetiedoilla tarkoitetaan, mitä osa-alueita on hallittava sekä miten niitä voitaisiin hallita kansainvälisesti verkostoituneen yrityksen näkökulmasta. Näiden lisäksi kartoitettiin ja vertailtiin erilaisia kehittämisvaihtoehtoja. Teorioista luotiin itsearviointityökalu kohdeyrityksen tuotannon tuotetiedon nykytilan kuvausta ja –analyysia varten. Löydetyt kehittämistarpeet priorisoitiin ja valituille kehityskohteille pohdittiin ratkaisuehdotuksia kaksivaiheisen kehittämismallin mukaisesti.
Resumo:
This paper presents the fundamental principles, instrumentation and selected applications of comprehensive two-dimensional gas chromatography (GC × GC). In this technique, introduced in 1991, two capillary columns are coupled and proper modulating interfaces continuously collect the eluate from the first column, transferring it to the second column. The result is a geometric increment in the chromatographic resolution, ensuring separation of extremely complex mixtures in time periods shorter or comparable to those of analysis using conventional gas chromatography and with better detectabilities and sensitivities.
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A simple liquid chromatographic method was optimized for the quantitative determination of terbinafine in pharmaceutical hydroalcoholic solutions and tablets, and was also employed for a tablet dissolution test. The analysis was carried out using a RP-C18 (250 mm × 4.6 mm, 5 μm) Vertical® column, UV-Vis detection at 254 nm, and a methanol-water (95:5, v/v) mobile phase at a flow-rate of 1.2 mL min-1. Method validation investigated parameters such as linearity, precision, accuracy, robustness and specificity, which gave results within the acceptable range. The tablets dissolution was quite fast: 80% of the drug was dissolved within 15 min.
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Preparative high-speed counter-current chromatography (HSCCC) was successfully applied for separation and purification of sesquiterpenoids from an extract of Tussilago farfara L. with a two-phase solvent system composed of n-hexane-ethyl acetate- methanol-water (1:0.5:1.1:0.3, v/v/v/v). The separation produced a total of 32 mg of tussilagone, 18 mg of 14-acetoxy-7β-(3'-ethyl cis-crotonoyloxy)-lα-(2'-methyl butyryloxy)-notonipetranone and 21 mg of 7β-(3'-ethyl cis-crotonoyloxy)-lα-(2'- methyl butyryloxy)-3,14-dehydro-Z-notonipetranone from 500 mg of the crude extract in one step separation with the purity of 99.5, 99.4 and 99.1%, respectively, as determined by HPLC. The structures of these compounds were identified by ESI-MS, ¹H-NMR and 13C-NMR.
Resumo:
Analysis of seven pesticides in sediments was successfully achieved using comprehensive two-dimensional gas chromatography with micro-electron capture detection, as it provided higher sensitivity and less matrix interference. Repeatability and intermediate precision of peak areas and heights were less than 4% and the recovery percentage for the analytes ranged from 52 to 115%. Instrumental LOD and LOQ were in the range of 0.60 to 2.31 μg L-1 and 1.83 to 5.62 μg L-1, respectively. Concentrations of 3.34 μg kg-1 (dry basis) for trifloxystrobin and azoxystrobin (below the LOQ) were found in a sediment sample.
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A method using liquid chromatography has been developed and validated for determination of buclizine in pharmaceutical formulations and in release studies. Isocratic chromatography was performed on a C18 column with methanol:water (80:20 v/v, pH 2.6) as mobile phase, at a flow rate of 1.0 mL/min, and UV detection at 230 nm. The method was linear, accurate, precise, sensible and robust. The dissolution test was optimized and validated in terms of dissolution medium, apparatus agitation and rotation speed. The presented analytical and dissolution procedures can be conveniently adopted in the quality and stability control of buclizine in tablets and oral suspension.
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Supercritical fluid extraction was used to extract active compounds from the Chinese traditional medicinal D. dasycarpus under the pressure of 30 MPa and temperature of 45 ºC. Further separation and purification was established by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.8:1.3:0.9, volume ratio). The separation yielded a total of 47 mg of dictamnine, 24 mg of obacunone and 83 mg of fraxinellone from 1.0 g of the crude extract in one step separation with the purity of 99.2, 98.4 and 99.0%, respectively, as determined by HPLC. The chemical structures of these compounds were identified by ESI-MS, IR, ¹H-NMR and 13C-NMR.
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Brazilian petroleum is known by its high acidity due to the presence of acidic constituents, especially naphthenic acids (NA). The total characterization of the NA in petrochemical samples has been receiving special attention in research and comprises an analytical challenge, mainly due to the complexity of their mixtures. Gas chromatography with mass detector (GC/MS) is the technique of analysis more used, but recently comprehensive two-dimensional gas chromatography (GC × GC) has been used, due to its high resolution, peak capacity and sensitivity. The goal of this article is to discuss the techniques for sample preparation and analysis of NA in petroleum.
Resumo:
The technique of pH-zone-refining counter-current chromatography was successfully applied to preparatively separate three C19-diterpenoid alkaloids from the crude extracts of Aconitum carmichaelii for the first time using a two-phase solvent system of petroleum ether-ethyl acetate-methanol-water (5:5:1:9, v/v/v/v). Mesaconitine (I), hypaconitine (II), and deoxyaconitine (III) were obtained from 2.5 g of the crude alkaloids in a one-step separation; the yields were 4.16%, 16.96%, and 5.05%, respectively. The purities of compounds I, II, and III were 93.0%, 95%, and 96%, respectively, as determined by HPLC. The chemical structures of the three compounds were identified by electrospray ionization mass spectrometry (ESI-MS) and NMR.
Resumo:
An effective method for the rapid separation and purification of three stilbenes from the radix of Polygonum cillinerve (Nakai) Ohwl by macroporous resin column chromatography combined with high-speed counter-current chromatography (HSCCC) was successfully established. In the present study, a two-phase solvent system composed of chloroform-n-butanol-methanol-water (4:1:4:2, v/v/v/v) was used for HSCCC separation. A one-step separation in 4 h from 150 mg of crude extract produced 26.3 mg of trans-resveratrol-3-O-glucoside, 42.0 mg of pieceid-2"-O-gallate, and 17.9 mg of trans-resveratrol with purities of 99.1%, 97.8%, and 99.4%, respectively, as determined by high-performance liquid chromatography (HPLC). The chemical structures of these compounds were identified by nuclear magnetic resonance (NMR) spectroscopy.