RESUMO
Compelling evidence is presented that sub-micron picoplankton shape, internal structure and orientation in combination leads to a disproportionate enhancement of differential forward scatter compared with differential side scatter when analyzed with a flow cytometer. Theoretical evidence is provided which results in an order of magnitude amplification in the forward scatter direction, with little or no change in the side scatter: this discounts the possibility of "doublets" caused by multiple particles simultaneously present in the laser beam. Observational evidence from progressively finer filtered seawater samples shows up to three orders of magnitude enhancement in the forward scatter direction and sizes of Prochlorococcus close to that reported in the literature (0.61 ± 0.17 µm). It therefore seems likely that flow cytometrically observed "bi-modal size distributions" of Prochlorococcus are instead the manifestation of intra-population differences in shape (spherical - prolate with preferential alignment) and internal structure (homogenous - heterogenous).
Assuntos
Citometria de Fluxo/instrumentação , Prochlorococcus/citologia , Espalhamento de Radiação , Água do Mar/microbiologia , Synechococcus/citologia , LuzRESUMO
Phosphorus (P) loss from agricultural areas to waterbodies is a worldwide concern. However, the effect of soil source and transport factors, such as clay (C) content and slope (S), on the magnitude of the P transport in Brazilian subtropical soils is still understudied. The objectives of this study were i) to quantify the loss of P fractions by runoff in areas receiving pig slurry application and with variations in S and C content; ii) propose an environmental critical limit model of P (P-threshold) for Brazilian subtropical soils. Thus, two series of experiments were conducted from 2016 to 2018, one under a Nitisol with 642 g kg-1 of C and another under a Cambisol with 225 g kg-1 of C. The treatments were four P rates (0, 56, 112 and 224 kg P ha-1 year-1) superficially applied as pig slurry, on Tifton (Cynodon sp) pasture, and three S (10, 20 and 30% in the Nitisol and 15, 25 and 35% in Cambisol). P losses increased in both soils as the S and P rates rose. The Nitisol showed P losses three times higher than the Cambisol. Soil S above 25% promotes P losses at a rate three times higher than in soil below this limit. Therefore, we propose a P-threshold model for Mehlich-1 extractable P levels for Brazilian subtropical soils as: "P-threshold = (42.287 + C) - (0.230 S + 0.0123 C S)" in soils with a S ≤ 25% and "P-threshold = (42.287 + C) - (-0.437 S + 0.039 C S)" in soils with a S >25%, where both C and S are shown in percentage. The soil clay content and slope are aggravating factors to the P transfer process, thus must be considered in suitable models to predict the P losses risk.
RESUMO
Depth-resolved flow cytometric observations have been used to determine the size distribution and refractive index (RI) of picoplankton throughout the Atlantic Ocean. Prochlorococcus frequently showed double size distribution peaks centered on ${0.75 \pm 0.25}$0.75±0.25 and ${1.75 \pm 0.25}\,\,{\rm \unicode{x00B5}{\rm m}}$1.75±0.25µm; the smallest peak diameters were ${\le}{0.65}\,\,{\rm \unicode{x00B5}{\rm m}}$≤0.65µm in the equatorial upwelling with larger cells (${\sim}{0.95}\,\,{\rm \unicode{x00B5}{\rm m}}$â¼0.95µm) in the surface layers of the tropical gyres. Synechococcus was strongly monodispersed: the smallest (${\sim}{1.5}\,\,{\rm \unicode{x00B5}{\rm m}}$â¼1.5µm) and largest cells (${\sim}{2.25{-}2.50}\,\,{\rm \unicode{x00B5}{\rm m}}$â¼2.25-2.50µm) were encountered in the lowest and highest abundance regions, respectively. Typical RI for Prochlorococcus was found to be ${\sim}{1.06}$â¼1.06, whereas for Synechococcus surface RI varied between 1.04-1.08 at high and low abundances, respectively.
Assuntos
Prochlorococcus/crescimento & desenvolvimento , Água do Mar/microbiologia , Synechococcus/crescimento & desenvolvimento , Oceano Atlântico , Clorofila/análise , Contagem de Colônia Microbiana , Ecossistema , Citometria de Fluxo/métodos , Óptica e Fotônica , Prochlorococcus/citologia , Synechococcus/citologiaRESUMO
Due to their high anti-oxidant activity, phlorotannins represent potential natural alternatives to synthetic preservatives currently used within the food industry. However, their successful integration into food products requires research into their chemical integrity, particularly when selecting appropriate storage conditions. Subsequently, this study aims to investigate the stability of low molecular weight phlorotannin fractions from Fucus vesiculosus (L.). Powder and aqueous fractions were stored under five different conditions for 10weeks. Phlorotannin stability was determined using Q-ToF-MS and UPLC-TQD-MS/MS and a DPPH assay. After 10weeks of storage, fractions suspended in an aqueous matrix underwent oxidation when exposed to continuous atmospheric oxygen and thermal degradation when exposed to a constant temperature of 50°C, resulting in decreases in radical scavenging activity (p<0.001). Phlorotannins remained stable under all other storage conditions. This study highlights phlorotannins as highly stable polymers, under certain storage conditions, with an excellent capacity for scavenging radicals.
Assuntos
Antioxidantes/química , Conservantes de Alimentos/química , Fucus/química , Taninos/química , Antioxidantes/isolamento & purificação , Compostos de Bifenilo/química , Conservantes de Alimentos/isolamento & purificação , Estrutura Molecular , Peso Molecular , Picratos/química , Espectrometria de Massas em Tandem , Taninos/isolamento & purificaçãoRESUMO
Plant extracts have traditionally been used as sources of natural antimicrobial compounds, although in many cases, the compounds responsible for their antimicrobial efficacy have not been identified. In this study, crude and dialysed extracts from dandelion root (Taraxacum officinale) were evaluated for their antimicrobial properties against Gram positive and Gram negative bacterial strains. The methanol hydrophobic crude extract (DRE3) demonstrated the strongest inhibition of microbial growth against Staphylococcus aureus, methicillin-resistant S. aureus and Bacillus cereus strains. Normal phase (NP) fractionation of DRE3 resulted in two fractions (NPF4 and NPF5) with enhanced antimicrobial activity. Further NP fractionation of NPF4 resulted in two fractions (NPF403 and NPF406) with increased antimicrobial activity. Further isolation and characterisation of compounds in NPF406 using liquid chromatography solid phase extraction nuclear magnetic resonance LC-SPE-NMR resulted in the identification of 9-hydroxyoctadecatrienoic acid and 9-hydroxyoctadecadienoic acid, while the phenolic compounds vanillin, coniferaldehyde and p-methoxyphenylglyoxylic acid were also identified respectively. The molecular mass of these compounds was confirmed by LC mass spectroscopy (MS)/MS. In summary, the antimicrobial efficacy of dandelion root extracts demonstrated in this study support the use of dandelion root as a source of natural antimicrobial compounds.
Assuntos
Antibacterianos/farmacologia , Bacillus cereus/efeitos dos fármacos , Extratos Vegetais/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Taraxacum/química , Cromatografia Líquida , Espectroscopia de Ressonância Magnética , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Fenóis/química , Extratos Vegetais/química , Raízes de Plantas/química , Espectrometria de Massas em TandemRESUMO
Antimicrobial properties of ethanol and water extracts from eight Asteraceae species were investigated against three Gram positive (Staphylococcus aureus, MRSA and Bacillus cereus) and two Gram negative (Escherichia coli and Salmonella typhimurium) bacterial strains. Ethanol extracts from Centaurea scabiosa, Arctium minus, Taraxacum officinale, Centaurea nigra and Cirsium palustre demonstrated antimicrobial activity against strains of S. aureus, MRSA and B. cereus (MIC=187.5-365µg/ml). Ethanol extracts also had higher antioxidant activities and phenolic content demonstrating a link between these compounds and the bioactivity of these extracts. Further investigation into the phenolic content of ethanol extracts using UPLC-MS/MS lead to the identification and quantification of numerous phenolic compounds in all species including; 18 from Cirsium arvense, 16 from Cirsium vulgare, 19 from C. palustre, 15 from C. nigra, 17 from C. scabiosa, 14 from Sonchus asper, 17 from A. minus and 11 from T. officinale.
Assuntos
Anti-Infecciosos/uso terapêutico , Antioxidantes/uso terapêutico , Asteraceae/microbiologia , Cromatografia Líquida/métodos , Testes de Sensibilidade Microbiana , Espectrometria de Massas em Tandem/métodosRESUMO
The combination of hyphenated techniques, LC-SPE-NMR and LC-MS, to isolate and identify minor isomeric compounds from an ethyl acetate fraction of Taraxacum officinale root was employed in this study. Two distinct fractions of 4-hydroxyphenylacetic acid derivatives of inositol were isolated and characterised by spectroscopic methods. The (1)H NMR spectra and MS data revealed two groups of compounds, one of which were derivatives of the di-4-hydroxyphenylacetic acid derivative of the inositol compound tetrahydroxy-5-[2-(4-hydroxyphenyl)acetyl] oxycyclohexyl-2-(4-hydroxyphenyl) acetate, while the other group consisted of similar tri-substituted inositol derivatives. For both fractions the derivatives of inositols vary in the number of 4-hydroxyphenylacetic acid groups present and their position and geometry on the inositol ring. In total, three di-substituted and three tri-substituted 4-hydroxyphenylacetic acid inositol derivates were identified for the first time along with a further two previously reported di-substituted inositol derivatives.
Assuntos
Inositol/química , Fenilacetatos/isolamento & purificação , Raízes de Plantas/química , Taraxacum/química , Cromatografia Líquida de Alta Pressão , Espectroscopia de Ressonância Magnética , Fenilacetatos/química , Espectrometria de Massas em TandemRESUMO
Freeze-dried fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit were extracted sequentially using non-polar to polar solvents, with further separation carried out on polar extracts by molecular weight cut off dialysis. The fenugreek ethyl acetate crude extract (FGE3) demonstrated the highest antioxidant activity, in terms of Trolox Equivalents (TE), for both the DPPH (35.338±0.908 mg TE/g) and FRAP (77.352±0.627 mg TE/g) assays. This extract also contained the highest phenolic content, in terms of Gallic Acid Equivalents (GAE) (106.316±0.377 mg GAE/g). Despite having considerably lower antioxidant activity than fenugreek, the highest antioxidant activities for bitter fruit were observed in the hexane (BME1) and methanol hydrophilic<3.5 kDa dialysed (BME4<3.5 kDa) extracts, while the highest phenolic content was found in the methanol hydrophilic>3.5 kDa (BME4>3.5 kDa) dialysed extract. UPLC-MS was used to quantify 18 phenolic compounds from fenugreek and 13 from bitter melon in active crude extracts. The flavonoids apigenin-7-O-glycoside (1955.55 ng/mg) and luteolin-7-O-glycoside (725.50 ng/mg) were the most abundant compounds in FGE3, while bitter melon extracts contained only small amounts of mainly phenolic acids. A further 5 fenugreek and 1 bitter melon compounds were identified in trace amounts from the same extracts, respectively.
Assuntos
Antioxidantes/química , Momordica charantia/química , Fenóis/química , Extratos Vegetais/química , Trigonella/química , Cromatografia Líquida de Alta Pressão , Frutas/química , Espectrometria de MassasRESUMO
The use of small angle neutron scattering, SANS, neutron reflectivity, NR, and surface tension to study the mixing properties of the biosurfactant rhamnolipid with a conventional anionic surfactant, sodium dodecyl 6-benzene sulfonate, LAS, is reported. The monorhamnose rhamnolipid, R1, mixes close to ideally with LAS at the air-water interface, whereas for mixtures of LAS with the dirhamnose rhamnolipid, R2, the LAS strongly partitions to the air-water interface relative to R2, probably because of the steric hindrance of the larger R2 headgroup. These trends in the binary mixtures are also reflected in the ternary R1/R2/LAS mixtures. However, for these ternary mixtures, there is also a pronounced synergy in the total adsorption, which reaches a maximum for a LAS/rhamnolipid mole ratio of about 0.6 and a R1/R2 mol ratio of about 0.5, an effect which is not observed in the binary mixtures. In solution, the R1/LAS mixtures form relatively small globular micelles, L(1), at low surfactant concentrations (<20 mM), more planar structures (lamellar, L(α), unilamellar/multilamellar vesicles, ulv/mlv) are formed at higher surfactant concentrations for R1 and LAS rich compositions, and a large mixed phase (L(α)/L(1) and L(1)/L(α)) region forms at intermediate surfactant compositions. In contrast, for the R2/LAS mixtures, the higher preferred curvature of R2 dominates the phase behavior. The predominant microstructure is in the form of small globular micelles, except for solution compositions rich in LAS (>80 mol % LAS) where more planar structures are formed. For the ternary mixtures, there is an evolution in the resulting phase behavior from one dominated by L(1) (R2 rich) to one dominated by planar structures, L(α), (R1, LAS rich), and which strongly depends upon the LAS/rhamnolipid and R1/R2 mole ratio.
Assuntos
Benzenossulfonatos/química , Tensoativos/química , Adsorção , Ânions , Glicolipídeos/química , Luz , Micelas , Modelos Estatísticos , Nêutrons , Espalhamento a Baixo Ângulo , Propriedades de Superfície , Tensão SuperficialRESUMO
The self-assembly in solution and adsorption at the air-water interface, measured by small-angle neutron scattering, SANS, and neutron reflectivity, NR, of the monorhamnose and dirhamnose rhamnolipids (R1, R2) and their mixtures, are discussed. The production of the deuterium-labeled rhamnolipids (required for the NR studies) from a Pseudomonas aeruginosa culture and their separation into the pure R1 and R2 components is described. At the air-water interface, R1 and R2 exhibit Langmuir-like adsorption isotherms, with saturated area/molecule values of about 60 and 75 Å(2), respectively. In R1/R2 mixtures, there is a strong partitioning of R1 to the surface and R2 competes less favorably because of the steric or packing constraints of the larger R2 dirhamnose headgroup. In dilute solution (<20 mM), R1 and R2 form small globular micelles, L(1), with aggregation numbers of about 50 and 30, respectively. At higher solution concentrations, R1 has a predominantly planar structure, L(α) (unilamellar, ULV, or bilamellar, BLV, vesicles) whereas R2 remains globular, with an aggregation number that increases with increasing surfactant concentration. For R1/R2 mixtures, solutions rich in R2 are predominantly micellar whereas solutions rich in R1 have a more planar structure. At an intermediate composition (60 to 80 mol % R1), there are mixed L(α)/L(1) and L(1)/L(α) regions. However, the higher preferred curvature associated with R2 tends to dominate the mixed R1/R2 microstructure and its associated phase behavior.
Assuntos
Lipídeos/química , Ramnose/química , Água/química , Adsorção , Ar , Química/métodos , Cromatografia Líquida de Alta Pressão , Concentração de Íons de Hidrogênio , Luz , Espectrometria de Massas/métodos , Modelos Químicos , Modelos Estatísticos , Nêutrons , Espalhamento de Radiação , Soluções , Propriedades de SuperfícieRESUMO
The antimicrobial activities of 60 naturally occurring and synthetic quinolines were studied. The quinolines were organised into seven structural subgroups and, using an in-house microtitre assay, were tested against a range of gram-positive and gram-negative bacteria, including a hospital isolate of meticillin-resistant Staphylococcus aureus (MRSA). The quinolines exhibiting good bioactivity [i.e. low minimum inhibitory concentration (MIC)] against two S. aureus strains were then assessed for their antimicrobial activity against a range of eight clinically isolated MRSA strains. The study showed that 30 of the tested compounds displayed antimicrobial activity, mostly against gram-positive bacteria. The effects of substituent groups on the bioactivity of these quinolines have also been discussed. The quinoline 4-hydroxy-3-iodo-quinol-2-one (11) exhibited significant antimicrobial activity, being active against the MRSA clinical isolates with MIC values comparable with the antibiotic vancomycin used in the treatment of MRSA infections. In particular, 4-hydroxy-3-iodo-quinol-2-one (11) showed MIC values of 0.097 microg/mL against an Irish hospital MRSA-1 strain and 0.049 microg/mL against a distinct MRSA strain as well as a non-typeable MRSA strain.
Assuntos
Antibacterianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Quinolinas/farmacologia , Antibacterianos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Quinolinas/química , Relação Estrutura-AtividadeRESUMO
The ethyl acetate extract of the leaves of Melicope vitiflora was separated by column chromatography and the resulting fractions tested for their bioactivity towards methicillin-resistant-Staphylococcus aureus (MRSA) and Micrococcus luteus (ML). The bioactive column chromatography fractions were further separated by preparative TLC and dereplication was carried out on them by first subjecting them to electrospray ionisation-ion trap mass spectrometry (ESI-MS(n)). The resulting molecular masses, their fragmentation patterns in addition to the chemnet database (www.chemnetbase.com) were used to aid in the structural elucidation of some of the compounds by permitting comparison with known structures of natural origin. Some molecular masses and the corresponding fragmentations were found that did not correlate with any known compounds thus revealing potentially novel natural products that could be investigated on a larger scale and could ultimately find application as new drugs against MRSA and other multi drug resistant microorganisms. Structures are also proposed for known compounds that have not been previously reported for M. vitiflora.
Assuntos
Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Extratos Vegetais/análise , Extratos Vegetais/farmacologia , Folhas de Planta/química , Rutaceae/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Antibacterianos/análise , Cromatografia em Camada Fina , Dióxido de Silício/químicaRESUMO
ABSTRACT Aluminum (Al) is toxic to many plant pathogens, including Thielaviopsis basicola and Phytophthora parasitica var. nicotianae. Because fungi-toxicity of Al has been described in soils over a wide pH range, multiple species of Al may be responsible for pathogen suppression. The goals of this work were to determine the sensitivity of T. basicola and P. para-sitica var. nicotianae to Al over a range of pH values, quantify the toxicity of monomeric Al species to production of sporangia of P. parasitica var. nicotianae and chlamydospores of T. basicola, and detect the accumulation of Al in pathogen structures. A complete factorial treatment design was used with Al levels ranging from 0 to 100 muM and pH levels ranging from 4 to 6 in a minimal salts medium. The chemistry of test solutions was modeled using GEOCHEM-PC. Colonies were grown in 5% carrot broth, and after 1 or 2 days, the nutrient solution was removed, colonies were rinsed with water, and Al test solutions were added to each of four replicate plates. After 2 days, propagules were counted and colonies were stained with the Al-specific, fluorescent stain lumogallion. The oomycete P. parasitica var. nicotianae was sensitive to multiple monomeric Al species, whereas sensitivity of T. basicola to Al was pH-dependent, suggesting that only Al(3+) is responsible for suppression of this fungal pathogen. Chlamydospore production by T. basicola was inhibited at pH values <5.0 and Al levels >20 muM, whereas sporangia production by P. parasitica was inhibited at Al levels as low as 2 muM across all pH values tested. The lumogallion stain was an effective technique for detection of Al in fungal tissues. Aluminum accumulated in sporangia and zoospores of P. parasitica var. nicotianae and in nonmelanized chlamy-dospores of T. basicola, but not in cell walls of either organism. The differential sensitivity of the two organisms may indicate that true fungi respond differently to Al than members of the oomycota, which are more closely related to plants.
RESUMO
The mechanistic basis for cation amelioration of Al rhizotoxicity in soybean was investigated through a series of studies comparing protective effects of Ca and Mg against Al inhibition of root elongation in a background 0.8 mM CaSO4 solution (pH 4.3). A modified Gouy-Chapman-Stern model was used to evaluate the effect of cations on electrical potential and Al3+ activity at root plasma membrane surfaces. Activities of Al3+ up to 4.6 microM in the background solution inhibited soybean tap root elongation by more than 80%. There was little or no response in root elongation when Ca and Mg were added to background solutions in the absence of AL: When added to Al-toxic solutions in the micromolar concentration range, Mg was 100-fold more effective than Ca in alleviating Al toxicity, whereas both cations were equally effective when added in the millimolar concentration range. The protective effect of micromolar additions of Mg on root elongation was specific for Al and it failed to alleviate La rhizotoxicity. In contrast to wheat, Mg amelioration of Al toxicity to soybean root elongation at low Mg concentration could not be explained by changes in potential and Al3+ activity at the root plasma membrane surfaces as predicted by a Gouy-Chapman-Stern model. These results suggest that Mg is not acting as an indifferent cation when present at low concentration and implies the involvement of a mechanism other than pure electrostatic effects at the root surface.
Assuntos
Alumínio/toxicidade , Cálcio/metabolismo , Glycine max/efeitos dos fármacos , Glycine max/metabolismo , Magnésio/metabolismo , Absorção , Membrana Celular/metabolismo , Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Íons , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Eletricidade Estática , Propriedades de SuperfícieRESUMO
Superior effectiveness of Mg over Ca in alleviating Al rhizotoxicity cannot be accounted for by predicted changes in plasma membrane Al3+ activity. The influence of Ca and Mg on the production and secretion of citrate and malate, and on Al accumulation by roots was investigated with soybean genotypes Young and PI 416937 which differ in Al tolerance. In the presence of a solution Al3+ activity of 4.6 microM, citrate and malate concentrations of tap root tips of both genotypes increased with additions of either Ca up to 3 mM or Mg up to 50 microM. Citrate efflux rate from roots exposed to Al was only enhanced with Mg additions and exceeded malate efflux rates by as much as 50-fold. Maximum citrate release occurred within 12 h after adding Mg to solution treatments. Adding 50 microM Mg to 0.8 mM CaSO4 solutions containing Al3+ activities up to 4.6 microM increased citrate concentration of tap root tips by 3- to 5-fold and root exudation of citrate by 6- to 9-fold. Plants treated with either 50 microM Mg or 3 mM Ca had similar reductions in Al accumulation at tap root tips, which coincided with the respective ability of these ions to relieve Al rhizotoxicity. Amelioration of Al inhibition of soybean root elongation by low concentrations of Mg in solution involved Mg-stimulated production and efflux of citrate by roots.
Assuntos
Alumínio/toxicidade , Cálcio/metabolismo , Citratos/metabolismo , Glycine max/metabolismo , Magnésio/metabolismo , Malatos/metabolismo , Raízes de Plantas/metabolismo , Absorção , Membrana Celular/metabolismo , Hidrogênio/metabolismo , Concentração de Íons de Hidrogênio , Íons , Raízes de Plantas/crescimento & desenvolvimento , Glycine max/efeitos dos fármacos , Eletricidade Estática , Propriedades de SuperfícieRESUMO
The mechanistic basis for Al toxicity effects on root growth is still a matter of speculation, but it almost certainly involves decreased cell division at the root apex. In this series of experiments, we attempt to determine whether Al enters meristematic cells and binds to nuclei when roots are exposed to a low Al(3+) activity in solution. The methodology involved the use of the Al-sensitive stain lumogallion (3-[2,4 dihydroxyphenylazo]-2-hydroxy-5-chlorobenzene sulfonic acid), the DNA stain 4',6-diamino-phenylindole, and confocal laser scanning microscopy. Soybean (Glycine max L. Merr.) cv Young (Al-sensitive) and PI 416937 (Al-tolerant) genotypes were exposed to 1.45 microM Al(3+) for periods ranging from 30 min to 72 h, and then washed with 10 mM citrate to remove apoplastic Al. Fluorescence images show that within 30 min Al entered cells of the sensitive genotype and accumulated at nuclei in the meristematic region of the root tip. Substantial Al also was present at the cell periphery. The images indicated that the Al-tolerant genotype accumulated lower amounts of Al in meristematic and differentiating cells of the root tip and their cell walls. Collectively, the results support an important role for exclusion in Al tolerance.
Assuntos
Alumínio/metabolismo , Benzenossulfonatos/química , Núcleo Celular/metabolismo , Microscopia Confocal/métodos , Raízes de Plantas/metabolismo , Espectrometria de Fluorescência/métodos , Genótipo , Lasers , Glycine max/genética , Glycine max/metabolismoRESUMO
Supercritical fluid extraction (SFE) is an innovative soil remediation technology. To aid system evaluation and design, thermodynamic and kinetic parameters have been measured using a naphthalene contaminated, loamy sand at various water contents. The experimental results show that supercritical carbon dioxide can easily extract naphthalene from soil when the water content is below 10%. At low water contents, mass transfer is rapid and the equilibrium partition coefficient is independent of the soil's water content. However, the overall mass transfer coefficient, (kova), decreases by at least a factor of 200 as the water content increases from 10 to 20%.
Assuntos
Dióxido de Carbono/química , Descontaminação/métodos , Naftalenos/química , Poluentes do Solo , Água/química , Humanos , Naftalenos/análise , Poluentes do Solo/análise , TermodinâmicaRESUMO
OBJECTIVE: To explore the factors associated with waiting times for surgery in public hospitals. SETTING: Three major acute care public hospitals in one Area Health Service. PARTICIPANTS: 691 adult patients entered onto the computerised booking list between 16 and 22 November 1994, and then between 16 January and 12 February 1995, were interviewed prospectively and followed up over a minimum of 18 months. Data were obtained from the Area Health Service's computerised booking system and patient self-report. RESULTS: Relevant surgical specialty, urgency rating, employment status and health insurance status were significantly associated with waiting time. Age, hospital, sex, country of birth, education, marital status and holding a Health Care Card were not significantly associated with waiting time. Self-reported health status (as measured by the SF-36) was not associated with waiting time for surgery. CONCLUSIONS: Waiting time for surgery was not simply determined by how urgently patients need surgery, but also by the type of surgery needed and patient's employment and health insurance status. The extent of disability experienced by patients, as measured by the SF-36, was not reflected in waiting times for surgery.
Assuntos
Procedimentos Cirúrgicos Eletivos/estatística & dados numéricos , Programas Nacionais de Saúde/estatística & dados numéricos , Listas de Espera , Adulto , Idoso , Feminino , Hospitais Públicos/estatística & dados numéricos , Humanos , Masculino , Medicina/estatística & dados numéricos , Pessoa de Meia-Idade , New South Wales , EspecializaçãoRESUMO
The remuneration of medical practitioners working in public hospitals has emerged as a critical issue during the doctors dispute associated with the Medicare programme in New South Wales. In this paper the authors present the findings of a study, conducted at the Prince Henry/Prince of Wales Hospitals Group, of the costs of replacing the present sessional arrangements for treatment of non-changeable orthopaedic patients with a system of fee-for-service payments. Under certain assumptions, public hospitals could find that fee-for-service becomes a cheaper method of payment for certain surgical procedures.