Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 288
Filtrar
1.
Chem Commun (Camb) ; 56(79): 11819-11822, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-33021275

RESUMO

Accelerated rate calorimetric studies have been employed to study the exothermic and thermal runaway behaviour of some aprotic and protic ionic liquids based on several families of ions including the bis(flurorsulfonyl)imide anion ([FSI]-); it was found that the protic salts are safer than aprotic salts of the [FSI]- anion.

3.
Chem Commun (Camb) ; 53(47): 6288-6302, 2017 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-28534592

RESUMO

Thermo-electrochemical cells (also called thermocells) are promising devices for harvesting waste heat for the sustainable production of energy. Research into thermocells has increased significantly in recent years, driven by advantages such as their ability to continuously convert heat into electrical energy without producing emissions or consuming materials. Until relatively recently, the commercial viability of thermocells was limited by their low power output and conversion efficiency. However, there have lately been significant advances in thermocell performance as a result of improvements to the electrode materials, electrolyte and redox chemistry and various features of the cell design. This article overviews these recent developments in thermocell research, including the development of new redox couples, the optimisation of electrolytes for improved power output and high-temperature operation, the design of high surface area electrodes for increased current density and device flexibility, and the optimisation of cell design to further enhance performance.

4.
Haemophilia ; 23(1): 33-41, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27761964

RESUMO

INTRODUCTION: Development of inhibitors to human FVIII (hFVIII) significantly complicates the control of bleeding events in patients with haemophilia A. AIM: This prospective, multicentre, open-label, non-comparative, Phase II study evaluated the haemostatic activity of a recombinant B-domain-deleted porcine FVIII (r-pFVIII), in the treatment of non-life/non-limb-threatening bleeding in individuals with haemophilia A and FVIII inhibitors. METHODS: Acute bleeding episodes in patients with pFVIII inhibitor titres <0.8 BU mL-1 were treated with 50 U kg-1 body weight r-pFVIII. Those with pFVIII inhibitor titres of >0.8 BU mL-1 received an initial calculated r-pFVIII loading dose followed by 50 U kg-1 treatment dose. Treatment continued at 6-hourly intervals until bleeding was determined, controlled or till a maximum of eight doses was reached. RESULTS: All 25 bleeding episodes in nine patients (mean age: 23.7 years; range: 14-34 years) were controlled successfully with eight or fewer injections of r-pFVIII. The median time from bleeding onset to the administration of r-pFVIII was 5.7 h (range: 1.5-20.0 h). Twenty of the bleeding episodes (80%) were controlled with one treatment dose of r-pFVIII (with or without a loading dose, median dose: 200.8 U kg-1 ; range: 50-576 U kg-1 ) regardless of pFVIII level. r-pFVIII was well tolerated and no treatment-emergent serious adverse events were considered by the investigator to be related to r-pFVIII administration. CONCLUSION: The results suggest that FVIII replacement therapy with r-pFVIII could be a viable alternative to bypassing agents for the treatment of bleeding episodes in individuals with haemophilia A and FVIII inhibitors.


Assuntos
Hemofilia A/tratamento farmacológico , Hemorragia/tratamento farmacológico , Adolescente , Adulto , Animais , Fator VIII/uso terapêutico , Feminino , Humanos , Masculino , Estudos Prospectivos , Suínos , Adulto Jovem
5.
J Environ Manage ; 184(Pt 2): 178-185, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27697373

RESUMO

Coal seam (CS) gas operations coproduce water with gas from confined CS aquifers. This CS water represents a potential agricultural resource if the water is able to be chemically amended to comply with management guidelines. Stoichiometric quantities of sulphur and gypsum amendments can be used to neutralise the alkalinity and reduce the sodicity of CS water respectively. These amendments can either be mixed in-line at a water treatment plant or applied directly to land prior to the application of CS water (a practice termed land amendment irrigation - LAI). This study compared the efficacy of LAI with in-line chemical amendment of CS water and irrigation with non-saline, non-sodic and non-alkaline (good quality) water under field conditions in southern Queensland. Soil chemical properties, soluble Ca, Mg, K, Na, electrical conductivity (EC), pH, chloride and alkalinity, as well as saturated hydraulic conductivity were measured to determine the impact of the irrigation treatments on soil chemical and physical conditions. Irrigation of lucerne pasture using solid-set sprinklers applied a total of 6.7 ML/ha of each treatment irrigation water to the experimental plots over a 10-month period. Alkalinity was neutralised using LAI, with no increase in soil alkalinity observed. Soil sodicity did not exceed threshold electrolyte concentration values under either CS water irrigation treatment. Soil chemical and physical properties were comparable for both LAI and in-line chemical amendment of CS water. Soil saturated hydraulic conductivity was maintained under all irrigation treatments. Results showed that the constrained capacity of the irrigation system was unable to meet crop evapotranspiration demand. This resulted in accumulation of salt within the root-zone under the CS water treatments compared to the good quality water treatment. LAI successfully chemically amended Bowen Basin CS water facilitating its beneficial use for agricultural irrigation.


Assuntos
Carvão Mineral , Resíduos Industriais , Solo/química , Água Subterrânea , Humanos , Queensland , Sódio/química , Cloreto de Sódio/análise
6.
Opt Express ; 24(13): 14951-9, 2016 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-27410645

RESUMO

A holey cladding dielectric waveguide with square cross section is designed, simulated, fabricated and characterized. The TOPAS waveguide is designed to be single mode across the broad frequency range of 180 GHz to 360 GHz as shown by finite-difference time domain simulation and to robustly support simultaneous TE and TM mode propagation. The square fiber geometry is realized by pulling through a heat distribution made square by appropriate furnace design. The transmitted mode profile is imaged using a vector network analyzer with a pinhole at the receiver module. Good agreement between the measured mode distribution and the calculated mode distribution is demonstrated.

7.
Phys Chem Chem Phys ; 17(14): 8706-13, 2015 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-25820549

RESUMO

Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg(-1) of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1 : 1 salt to IL molar ratio, equivalent to 3.2 mol kg(-1) of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications.

8.
Int J Obes (Lond) ; 39(2): 199-207, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24984753

RESUMO

BACKGROUND: Physical activity (PA) has been consistently implicated in the etiology of obesity, whereas recent evidence on the importance of sedentary time remains inconsistent. Understanding of dose-response associations of PA and sedentary time with overweight and obesity in adults can be improved with large-scale studies using objective measures of PA and sedentary time. The purpose of this study was to examine the strength, direction and shape of dose-response associations of accelerometer-based PA and sedentary time with body mass index (BMI) and weight status in 10 countries, and the moderating effects of study site and gender. METHODS: Data from the International Physical activity and the Environment Network (IPEN) Adult study were used. IPEN Adult is an observational multi-country cross-sectional study, and 12 sites in 10 countries are included. Participants wore an accelerometer for seven consecutive days, completed a socio-demographic questionnaire and reported height and weight. In total, 5712 adults (18-65 years) were included in the analyses. Generalized additive mixed models, conducted in R, were used to estimate the strength and shape of the associations. RESULTS: A curvilinear relationship of accelerometer-based moderate-to-vigorous PA and total counts per minute with BMI and the probability of being overweight/obese was identified. The associations were negative, but weakened at higher levels of moderate-to-vigorous PA (>50 min per day) and higher counts per minute. No associations between sedentary time and weight outcomes were found. Complex site- and gender-specific findings were revealed for BMI, but not for weight status. CONCLUSIONS: On the basis of these results, the current Institute of Medicine recommendation of 60 min per day of moderate-to-vigorous PA to prevent weight gain in normal-weight adults was supported. No relationship between sedentary time and the weight outcomes was present, calling for further examination. If moderator findings are confirmed, the relationship between PA and BMI may be country- and gender-dependent, which could have important implications for country-specific health guidelines.


Assuntos
Acelerometria/estatística & dados numéricos , Prática Clínica Baseada em Evidências/estatística & dados numéricos , Promoção da Saúde , Atividade Motora , Obesidade/epidemiologia , Comportamento Sedentário , Adulto , Índice de Massa Corporal , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/etiologia , Inquéritos e Questionários
9.
Chem Soc Rev ; 43(23): 8132-49, 2014 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-25198613

RESUMO

Ionic liquids, as reaction media, and sonochemistry are two recently developing fields of chemistry that present some similarities. Firstly, they constitute separately unconventional approaches to reaction chemistry that, in many cases, generate improvements in yield, rate and selectivity compared to classical chemistry, or even change the mechanisms or products expected. In addition, both are often associated with green chemistry concepts as a result of their properties and their possible eco-friendly uses. A recent trend has been to combine these two technologies in a range of different applications and the results demonstrate very significant and occasionally surprising synergetic effects. Here we critically review the advantages and limitations of the ionic liquid/ultrasound combination in different applications in chemistry, to understand how, and in which respects, it could become an essential tool of sustainable chemistry in the future. Many practical and theoretical aspects associated with this combination of techniques are not understood or resolved and we discus where fundamental studies might further advance this field.

10.
Am J Physiol Gastrointest Liver Physiol ; 307(7): G760-8, 2014 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-25104497

RESUMO

To investigate the potential of therapies which reduce glucocorticoid action in patients with Type 2 diabetes we performed a randomized, double-blinded, placebo-controlled crossover study of acute glucocorticoid blockade, using the glucocorticoid receptor antagonist RU38486 (mifepristone) and cortisol biosynthesis inhibitor (metyrapone), in 14 men with Type 2 diabetes. Stable isotope dilution methodologies were used to measure the rates of appearance of glucose, glycerol, and free fatty acids (FFAs), including during a low-dose (10 mU·m⁻² ·min⁻¹) hyperinsulinemic clamp, and subgroup analysis was conducted in patients with high or low liver fat content measured by magnetic resonance spectroscopy (n = 7/group). Glucocorticoid blockade lowered fasting glucose and insulin levels and improved insulin sensitivity of FFA and glycerol turnover and hepatic glucose production. Among this population with Type 2 diabetes high liver fat was associated with hyperinsulinemia, higher fasting glucose levels, peripheral and hepatic insulin resistance, and impaired suppression of FFA oxidation and FFA and glycerol turnover during hyperinsulinemia. Glucocorticoid blockade had similar effects in those with and without high liver fat. Longer term treatments targeting glucocorticoid action may be useful in Type 2 diabetes with and without fatty liver.


Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Metabolismo Energético/efeitos dos fármacos , Antagonistas de Hormônios/uso terapêutico , Fígado/efeitos dos fármacos , Mifepristona/uso terapêutico , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Receptores de Glucocorticoides/antagonistas & inibidores , Glicemia/efeitos dos fármacos , Glicemia/metabolismo , Estudos Cross-Over , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Método Duplo-Cego , Inibidores Enzimáticos/uso terapêutico , Ácidos Graxos não Esterificados/sangue , Glicerol/sangue , Humanos , Hidrocortisona/metabolismo , Técnicas de Diluição do Indicador , Insulina/sangue , Fígado/metabolismo , Espectroscopia de Ressonância Magnética , Masculino , Metirapona/uso terapêutico , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/sangue , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Receptores de Glucocorticoides/metabolismo , Escócia , Esteroide 11-beta-Hidroxilase/antagonistas & inibidores , Esteroide 11-beta-Hidroxilase/metabolismo , Fatores de Tempo , Resultado do Tratamento
12.
Chem Commun (Camb) ; 50(66): 9228-50, 2014 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-24830849

RESUMO

As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today.


Assuntos
Líquidos Iônicos , Medicina
13.
J Phys Chem B ; 118(18): 4895-905, 2014 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-24712560

RESUMO

In order to expand our understanding of a potential zinc-based battery electrolyte, we have characterized the physical and transport properties of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium dicyanamide ([C4mpyr][dca]) containing various levels of both Zn(2+) and H2O. Detailed measurements of density, viscosity, conductivity, and individual anion and cation diffusion coefficients using pulsed-field-gradient (PFG) NMR combined with NMR chemical shifts and spin-lattice relaxation (T1) NMR experiments provide insights into the motion and chemical environment of all molecular species. We find that the various techniques for probing ion transport and dynamics form a coherent picture as a function of electrolyte composition. Zn(2+) addition causes a moderate reduction in the self-diffusion of the IL anion and cation, whereas the addition of H2O increases ion mobility by increasing the liquid's overall fluidity. Temperature-dependent (13)C T1 experiments of the dca carbon analyzed using Bloembergen-Purcell-Pound fits show monotonic slowing of anion dynamics with Zn(2+) addition, suggesting increased Zn(2+)/dca(-) association. T1 experiments show minimal change in the spin-lattice relaxation of cation or anion upon H2O addition, suggesting that H2O is playing no significant role in Zn(2+) speciation. Finally, we employ a novel electrophoretic NMR technique to directly determine the electrophoretic mobility of the C4mpyr cation, which we discuss in the context of impedance-based conductivity measurements.

14.
Eur J Pharm Sci ; 51: 34-44, 2014 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-24012589

RESUMO

The main focus of this study is to encapsulate hydrophobic drug curcumin in hydrophilic polymeric core such as poly(2-hydroxyethyl methacrylate) [PHEMA] nanoparticles from gelled ionic liquid (IL) to improve its efficacy. We have achieved 26.4% drug loading in a biocompatible hydrophilic polymer. Curcumin loaded PHEMA nanoparticles (C-PHEMA-NPs) were prepared by nano-precipitation method. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis showed that the prepared nanoparticles were spherical in shape and free from aggregation. The size and zeta potential of prepared C-PHEMA-NPs were about 300 nm and -33.4 mV respectively. C-PHEMA-NPs were further characterized by FT-IR spectroscopy which confirmed the existence of curcumin in the nanoparticles. X-ray diffraction and differential scanning calorimetry studies revealed that curcumin present in the PHEMA nanoparticles were found to be amorphous in nature. The anticancer activity of C-PHEMA-NPs was measured in ovarian cancer cells (SKOV-3) in vitro, and the results revealed that the C-PHEMA-NPs had better tumor cells regression activity than free curcumin. Flow cytometry showed the significant reduction in G0/G1 cells after treatment with C-PHEMA-NPs and molecular level of apoptosis were also studied using western blotting. Toxicity of PHEMA nanoparticles were studied in zebrafish embryo model and results revealed the material to be highly biocompatible. The present study demonstrates the curcumin loaded PHEMA nanoparticles have potential therapeutic values in the treatment of cancer.


Assuntos
Antineoplásicos/farmacologia , Curcumina/farmacologia , Metacrilatos/química , Nanopartículas/química , Poli-Hidroxietil Metacrilato/química , Polímeros/química , Animais , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Curcumina/química , Portadores de Fármacos/química , Fase G1/efeitos dos fármacos , Géis/química , Géis/farmacologia , Humanos , Tamanho da Partícula , Fase de Repouso do Ciclo Celular/efeitos dos fármacos , Peixe-Zebra
15.
Hong Kong Med J ; 19 Suppl 4: 39-41, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23775186

RESUMO

1. Reliable and valid interviewer-administered questionnaires were developed to investigate associations of perceived neighbourhood attributes of Hong Kong older adults with their walking for transportation and recreation. 2. Access to and availability of different types of services and destinations, provision of facilities for resting/sitting in the neighbourhood, and easy access to/from residential buildings may help maintain an active lifestyle by facilitating walking for transport in the neighbourhood. 3. Access to services, indoor places for walking, environmental aesthetics, low traffic, and absence of physical barriers may promote recreational walking..


Assuntos
Estilo de Vida , Características de Residência , Meios de Transporte , Caminhada/fisiologia , Idoso , Idoso de 80 Anos ou mais , Planejamento Ambiental , Feminino , Hong Kong , Humanos , Masculino , Projetos Piloto , Recreação , Inquéritos e Questionários
17.
Eur J Appl Physiol ; 113(3): 753-62, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22945269

RESUMO

Knowing the inter-unit variability, especially the technological error, is important when using many physiological measurement systems, yet no such inter-unit analysis has been undertaken on duplicate automated gas analysis systems. This study investigated the inter-unit performance of two identical ParvoMedics TrueOne 2400 automated gas analysis systems during a range of submaximal steady-state exercises performed on an electromagnetic cycle ergometer. Fifteen adult males were tested on two separate days a rest, 30, 60, 90, and 120 Watts with the duplicate gas analysis units arranged (1) collaterally (2 min of steady-state expired gas was alternately passed through each system), and (2) simultaneously (identical steady-state expired gas was passed simultaneously through both systems). Total within-subject variation (biological + technological) was determined from the collateral tests, but the unique inter-unit variability (technological error between identical systems) was shown by the simultaneous tests. Absolute percentage errors (APE), coefficient of variations (CV), effect sizes and Bland-Altman analyses were undertaken on the metabolic data, including expired ventilation (V (E)), oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)). The few statistically significant differences detected between the two duplicate systems were determined to have small or trivial effect sizes, and their magnitudes to be of little physiological importance. The total within-subject variations for VO(2), VCO(2) and V (E) each equated to a mean CV and mean APE value of ~4 and ~6 %, whilst the respective inter-unit technological errors equated to ~1.5 and ~2.1 %. The two ParvoMedics TrueOne 2400 systems demonstrated excellent inter-unit agreement.


Assuntos
Testes Respiratórios/instrumentação , Teste de Esforço , Gases/análise , Troca Gasosa Pulmonar , Adulto , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Processamento Eletrônico de Dados , Gases/metabolismo , Humanos , Masculino , Modelos Biológicos , Variações Dependentes do Observador , Oxigênio/análise , Oxigênio/metabolismo , Espirometria/instrumentação , Espirometria/métodos , Adulto Jovem
18.
Appl Microbiol Biotechnol ; 97(4): 1767-74, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22526779

RESUMO

Choline-based biocompatible salts were used as "nutrients" for the growth of Staphylococcus lentus bacteria. Increase in the growth rate of bacteria was observed, compared to conventional carbon sources. In the case of the ionic liquid, choline lactate, the increase was pronounced. Bacterial growth was correlated with power-time curve in an investigation monitored online by reaction calorimetry. From the power-time curve, three phases of the growth can be distinctly seen. Heat yield coefficients estimated for the growth of S. lentus were found to match well with those reported hitherto. A comparative study of heat yields (catabolic) between glucose and choline lactate revealed significant information; the heat yield due to choline lactate (Y (Q/S)) consumption and oxygen (Y (Q/O)) were 23.4 kJ/g and 435 kJ/mol and whereas that for glucose with oxygen were 9.6 kJ/g and 427 kJ/mol, respectively, showing clearly the preferential affinity of choline lactate by the bacteria rather than glucose. This study also established that the use of ionic liquids as nutrients can be monitored using bioreaction calorimetry.


Assuntos
Colina/metabolismo , Staphylococcus/crescimento & desenvolvimento , Staphylococcus/metabolismo , Metabolismo Energético , Glucose/metabolismo , Temperatura Alta , Cinética , Staphylococcus/química , Staphylococcus/genética
19.
Haemophilia ; 18(5): 798-804, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22512291

RESUMO

OBI-1 is a recombinant B-domain deleted porcine factor VIII (FVIII). FVIII treatment in those with haemophilia A may be complicated by the development of anti-FVIII antibodies (inhibitors) leading to a failure to respond to treatment with human FVIII. To compare the pharmacokinetics and safety of a single dose of OBI-1 with Hyate:C in subjects with haemophilia A and inhibitors, subjects were randomized to receive either Hyate:C followed by placebo or placebo followed by OBI-1 in a double-blind fashion. FVIII levels were assayed using both a one-stage coagulation assay (OSCA) and chromogenic assay. Pharmacokinetic parameters for FVIII were calculated for 6/9 subjects randomized; in three subjects baseline anti-porcine FVIII inhibitors led to a lack of measurable FVIII activity. Mean C(max) appeared higher for OBI-1 (OSCA: 176.00 U dL(-1), standard deviation ± 88.00; chromogenic: 151.00 ± 31.51 U dL(-1)) than Hyate:C (OSCA: 82.3 ± 19.22 U dL(-1); chromogenic: 52.67 ± 13.8 U dL(-1)). Mean AUC also appeared higher for OBI-1 (OSCA: 2082.87 ± 1323.43 U h(-1) dL(-1) ; chromogenic: 1817.28 ± 625.14 U h(-1) dL(-1)) than Hyate:C (OSCA: 1177.8 ± 469.49 U h(-1) dL(-1); chromogenic: 707.61 ± 420.05 U h(-1) dL(-1)). Two infusion-related events occurred: one with Hyate:C, one with placebo. Four of five subjects without anti-porcine FVIII inhibitors at baseline remained porcine FVIII inhibitor negative 29 days after infusion. A single dose of OBI-1 appears to have higher bioavailability than Hyate:C in subjects with haemophilia A without measurable anti-porcine FVIII inhibitors, and is well tolerated. These results should be confirmed in a larger phase 2/3 study.


Assuntos
Fator VIII/administração & dosagem , Fator VIII/farmacocinética , Hemofilia A/terapia , Adolescente , Adulto , Animais , Inibidores dos Fatores de Coagulação Sanguínea/sangue , Fator VIII/efeitos adversos , Fator VIII/antagonistas & inibidores , Hemofilia A/sangue , Humanos , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Fragmentos de Peptídeos/administração & dosagem , Fragmentos de Peptídeos/efeitos adversos , Fragmentos de Peptídeos/farmacocinética , Proteínas Recombinantes/administração & dosagem , Proteínas Recombinantes/efeitos adversos , Proteínas Recombinantes/farmacocinética , Suínos , Adulto Jovem
20.
Eur J Appl Physiol ; 112(7): 2539-47, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22075643

RESUMO

This study investigated the performance of the portable Cortex Metamax 3B (MM3B) automated gas analysis system during both simulated and human exercise using adolescents. Repeated measures using a Gas Exchange System Validator (GESV) across a range of simulated metabolic rates, showed the MM3B to be adequately reliable (both percentage errors, and percentage technical error of measurements <2%) for measuring expired ventilation (V (E)), oxygen consumption (VO(2)), and carbon dioxide production (VCO(2)). Over a 3 h period, the MM3B was shown to be acceptably stable in measuring gas fractions, as well as V (E), VO(2), and VCO(2) generated by the GESV, especially at moderate and high metabolic rates (drifts <2% and of minor physiological significance). Using eight healthy adolescents during rest, moderate, and vigorous cycle ergometry, the validity of the MM3B was tested against the primary criterion Douglas bag method (DBM) and a secondary criterion machine known to be accurate, the Jaeger Oxycon Pro system. No significant errors in V (E) were noted, yet the MM3B significantly overestimated both VO(2) and VCO(2) by approximately 10-17% at moderate and vigorous exercise as compared to the DBM and at all exercise levels compared to the Oxycon Pro. No significant differences were seen in any metabolic variable between the two criterion systems (DBM and Oxycon Pro). It is concluded the MM3B produces acceptably stable and reliable results, but is not adequately valid during moderate and vigorous exercise without some further correction of VO(2) and VCO(2).


Assuntos
Capnografia/instrumentação , Dióxido de Carbono/análise , Oximetria/instrumentação , Oxigênio/análise , Troca Gasosa Pulmonar/fisiologia , Espirometria/instrumentação , Adolescente , Adulto , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Masculino , Miniaturização , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...