RESUMO
HYPOTHESIS: One of the main drawbacks of metal-supported materials, traditionally prepared by the impregnation of metal salts onto pre-synthesized porous supports, is the formation of large and unevenly dispersed particles. Generally, the larger are the particles, the lower is the number of catalytic sites. Maximum atom exposure can be reached within single-atom materials, which appear therefore as the next generation of porous catalysts. EXPERIMENTS: Herein, we designed single iron atom-supported silica materials through sol-gel hydrothermal treatment using mixtures of a non-ionic surfactant (Pluronic P123) and a metallosurfactant (cetyltrimethylammoniumtrichloromonobromoferrate, CTAF) as porogens. The ratio between the Pluronic P123 and the CTAF enables to control the silica structural and textural properties. More importantly, CTAF acts as an iron source, which amount could be simply tuned by varying the non-ionic/metallo surfactants molar ratio. FINDINGS: The fine distribution of iron atoms onto the silica mesopores results from the iron distribution within the mixed micelles, which serve as templates for the polymerization of the silica matrix. Several characterization methods were used to determine the structural and textural properties of the silica material (XRD, N2 sorption isotherms and TEM) and the homogeneous distribution and lack of clustering of iron atoms in the resulting materials (elemental analysis, magnetic measurements, pair distribution function (PDF), MAS-NMR and TEM mapping). The oxidation and spin state of single-iron atoms determined from their magnetic properties were confirmed by DFT calculations. This strategy might find straightforward applications in preparing versatile single atom catalysts, with improved efficiency compared to nanosized ones.
RESUMO
HYPOTHESIS: Newtonian liquids, usually used as base oil lubricants, exhibit low viscosity under extreme thermal conditions, needed for the functioning of wind turbines. This is directly affecting the colloidal stability and the tribological properties of the formulations containing additives, such as MoS2. Here, it was hypothesized that the surface hydrophobization of MoS2 particles will allow for an increased colloidal stability of the resulting formulations, for temperatures as high as 80 °C. EXPERIMENTS: The antifriction properties and the thermal stability of the designed formulations were determined on submicron MoS2 particles dispersed in poly-α-olefins (PAO) base oils of different dynamic viscosities (from 32 to 1650 mPa·s at 25 °C). The submicron particles of MoS2 (300-500 nm in diameter) were synthesised by a simple one-pot solvothermal method under mild conditions. The resulting particles were hydrophobized in situ in PAO base oils using alkyltrichlorosilane grafting agents with two chain lengths (C8 and C18). FINDINGS: The covalent grafting of alkylsilanes through Mo-O-Si bonds was confirmed by DFT calculations and FT-IR measurements. Turbiscan optical analysis revealed that thermal and colloidal stabilities can be significantly improved depending on oil viscosity and chain length of the grafting agent. The formulations in the PAO65 oil remained highly stable (TSI < 1), even at 80 °C. Herein, we demonstrate the impact of hydrophobization degree on the tribological properties of the lubricants, which, importantly, could reach ultra-low friction coefficients, less than 0.02.
RESUMO
Olive stones (OS) were submitted to hydrothermal carbonisation (HTC) in order to evaluate the possibility of producing high added-value products, mainly furfural (FU) and 5-hydroxymethylfurfural (5-HMF) on one hand and hydrochars and carbons on the other hand. Temperature (160-240 °C), residence time (1-8 h), initial pH (1-5.5) and liquid/solid ratio (4-48 w/w) were systematically varied in order to study the main products and to optimise FU production. FU production yield up to 19.9 %, based on the hemicellulose content, was obtained. Other minor, but valuable, compounds such as 5-methylfurfural (5-MF) and some phenolic compounds were also produced. The hydrochar was carbonised at 900 °C, and the resultant carbon material was highly ultramicroporous with a peak of pore size distribution centred on 0.5 nm and a surface area as high as 1065 m2 g-1, typical of most carbon molecular sieves.
Assuntos
Carbono/química , Olea , Furaldeído/análogos & derivados , TemperaturaRESUMO
Tyre pyrolysis char (TPC), produced when manufacturing pyrolysis oil from waste tyre, was used as raw material to prepare activated carbons (ACs) by KOH activation. KOH to TPC weight ratios (W) between 0.5 and 6, and activation temperatures from 600 to 800 °C, were used. An increase in W resulted in a more efficient development of surface area, microporosity and mesoporosity. Thus, ACs derived from TPC (TPC-ACs) with specific surface areas up to 814 m(2) g(-1) were obtained. TPC, TPC-ACs and a commercial AC (CAC) were tested for removing Tetracycline (TC) in aqueous phase, and systematic adsorption studies, including equilibrium, kinetics and thermodynamic aspects, were performed. Kinetics was well described by the pseudo-first order model for TPC, and by a pseudo second-order kinetic model for ACs. TC adsorption equilibrium data were also fitted by different isotherm models: Langmuir, Freundlich, Sips, Dubinin-Radushkevich, Dubinin-Astokov, Temkin, Redlich-Peterson, Radke-Prausnitz and Toth. The thermodynamic study confirmed that TC adsorption onto TPC-ACs is a spontaneous process. TC adsorption data obtained in the present study were compared with those reported in the literature, and differences were explained in terms of textural properties and surface functionalities. TPC-ACs had similar performances to those of commercial ACs, and might significantly improve the economic balance of the production of pyrolysis oil from waste tyres.
Assuntos
Carvão Vegetal/química , Hidróxidos/química , Compostos de Potássio/química , Tetraciclina/análise , Poluentes Químicos da Água/análise , Adsorção , Carbono , Cinética , Temperatura , Tetraciclina/química , Poluentes Químicos da Água/químicaRESUMO
Roxarsone is included in chicken food as anticoccidial and mainly excreted unchanged in faeces. Microorganisms biotransform roxarsone into toxic compounds that leach and contaminate underground waters used for human consumption. This study evaluated roxarsone biotransformation by underground water microorganisms and the toxicity of the resulting compounds. Underground water from an agricultural field was used to prepare microcosms, containing 0.05 mM roxarsone, and cultured under aerobic or anaerobic conditions. Bacterial communities of microcosms were characterized by PCR-DGGE. Roxarsone degradation was measured by HPLC/HG/AAS. Toxicity was evaluated using HUVEC cells and the Toxi-ChromoTest kit. Roxarsone degradation analysis, after 15 days, showed that microcosms of underground water with nutrients degraded 90 and 83.3% of roxarsone under anaerobic and aerobic conditions, respectively. Microcosms without nutrients degraded 50 and 33.1% under anaerobic and aerobic conditions, respectively. Microcosms including nutrients showed more roxarsone conversion into toxic inorganic arsenic species. DGGE analyses showed the presence of Proteobacteria, Firmicutes, Actinobacteria, Planctomycetes and Spirochaetes. Toxicity assays showed that roxarsone biotransformation by underground water microorganisms in all microcosms generated degradation products toxic for eukaryotic and prokaryotic cells. Furthermore, toxicity increased when roxarsone leached though a soil column and was further transformed by the bacterial community present in underground water. Therefore, using underground water from areas where roxarsone containing manure is used as fertilizer might be a health risk.
Assuntos
Bactérias/metabolismo , Água Subterrânea/microbiologia , Roxarsona/metabolismo , Roxarsona/toxicidade , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biodegradação Ambiental , Biotransformação , Galinhas , Água Subterrânea/análise , Esterco/análise , Dados de Sequência Molecular , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Poluentes da Água/metabolismo , Poluentes da Água/toxicidadeRESUMO
Aqueous solutions of condensed tannins were submitted to hydrothermal carbonization (HTC) in a stainless steel autoclave, and the kinetics of hydrothermal carbon formation was investigated by changing several parameters: amount of tannin (0.5; 1.0; 1.5; 2.0 g in 16 mL of water), HTC temperature (130, 160, 180 and 200°C) and reaction times (from 1 to 720 h). The morphology and the structure of the tannin-based hydrothermal carbons were studied by TEM, krypton adsorption at -196°C and helium pycnometry. These materials presented agglomerated spherical particles, having surface areas ranging from 0.6 to 10.0 m(2) g(-1). The chemical composition of the hydrothermal carbons was found to be constant and independent of reaction time. HTC kinetics of tannin were determined and shown to correspond to first-order reaction. Temperature-dependent measurements led to an activation energy of 91 kJ mol(-1) for hydrothermal conversion of tannin into carbonaceous microspheres separable by centrifugation.
Assuntos
Biotecnologia/métodos , Carbono/química , Microesferas , Taninos/química , Temperatura , Água/farmacologia , Cinética , Tamanho da PartículaRESUMO
BACKGROUND: As a result of several clinical reports addressing coincidence or coprevalence of atopy and autoimmune disease such as multiple sclerosis and type I diabetes mellitus, there has been considerable interest in defining the relationship between the expression of allergic and autoimmune disease in populations of patients. Although thyroid autoimmunity has been regularly associated with chronic urticaria in children, the cofrequency of thyroid autoimmunity and atopic dermatitis has not yet been investigated. The aim of the study was to describe our experience with children affected by atopic dermatitis and associated thyroid autoimmunity. METHODS: From January 2010 to December 2012, 147 children affected by atopic dermatitis were consecutively referred to the Pediatric Clinic of the Pediatric Department at the Second University of Naples. Seventy healthy children of comparable ages, unaffected by atopic dermatitis, atopy or thyroid disease, served as a control group. RESULTS: On the basis of skin prick test results we selected 54 IgE-mediated (36.7%) and 93 non-IgE-mediated AD (63.3%) children. Fourteen of 147 patients (9.52%) showed increased levels of antithyroid antibodies. CONCLUSIONS: Our results therefore suggest that atopy, especially food allergy, and autoimmunity are two potential outcomes of dysregulated immunity.
Assuntos
Autoimunidade , Dermatite Atópica/imunologia , Glândula Tireoide/imunologia , Criança , Feminino , Humanos , Masculino , Fatores de RiscoRESUMO
A set of epoxy resin composites filled with 0.25-2.0 wt.% of commercially available ENSACO carbon black (CB) of high and low surface area (CBH and CBL respectively) has been produced. The results of broadband dielectric spectroscopy of manufactured CB/epoxy below the percolation threshold in broad temperature (200 K to 450 K) and frequency (20 Hz to 1 MHz) ranges are reported. The dielectric properties of composites below the percolation threshold are mostly determined by alpha relaxation in pure polymer matrix. The glass transition temperature for CB/epoxy decreases in comparison with neat epoxy resin due to the extra free volume at the polymer-filler interface. At room temperature, the dielectric permittivity is higher for epoxy loaded with CBH additives. In contrast, at high temperature, the electrical conductivity was found to be higher for composites with CBL embedded. The established influence of the CB surface area on the broadband dielectric characteristics can be exploited for the production of effective low-cost antistatic paints and coatings working at different temperatures.
RESUMO
The structure of a series of activated carbons prepared from anthracite by chemical activation has been studied using wide-angle x-ray scattering, molecular dynamics and Raman spectroscopy. The BET surface areas of the investigated samples are in the range 1500-3430 m(2) g(-1) and the average pore sizes vary from 0.75 to 1.35 nm. The diffraction measurements were carried out to a maximum value of the scattering vector K(max) = 22 Å(-1). The obtained diffraction data have been converted to a real space representation in the form of the pair correlation function. The structure of the studied samples consists of one or two graphite-like layers, stacked without spatial correlations. The size of the ordered layer region is approximately 24 Å. The atomic arrangement within an individual layer has been described in terms of paracrystalline ordering, in which lattice distortions are propagated proportionally to the square root of inter-atomic distances. The paracrystalline structure has been simulated by introducing the Stone-Thrower-Wales, mono-vacancy and di-vacancy defects, randomly distributed in the network. These defects lead to the formation of a defected network with the presence of non-hexagonal rings in which distortion of the structure extends outside of a defect region. Computer generated structural models have been relaxed at room temperature using the reactive empirical bond order potential for intra-layer interactions and the Lennard-Jones potential for inter-layer interactions. For such generated models the structure factors and the pair correlation functions were computed. A good agreement between the simulation results and the experimental data in both reciprocal and real space provides evidence for the correctness of the proposed models. The Raman data support the validity of these models. Porosity of the activated anthracites is discussed in relation to their defective structure.
RESUMO
A potential role of Helicobater Pylori (HP) infection in several extra-intestinal pathologies has been recently suggested. The aim of our study was to assess the role of serology positive for HP in atopic and non atopic infants and children affected by atopic dermatitis, urticaria, rhinitis and asthma. We included 615 children affected by atopic diseases. According to prick test positivity and age, we divided the patients into two groups: atopic or non-atopic patients and infants (0-2 years) or children (2-12 years). The serum levels of antibodies for H. pylori immunoglobulin G were measured by using an ELISA test. We found a not significant difference between group 1 and group 2 about atopy. There was a significant higher frequency of HP positive serology in older children. As for infants, a higher significant prevalence of HP positive serology was found in non-atopic patients. HP positive serology was significantly higher only in non-atopic infants affected by atopic dermatitis and urticaria than in atopic. In group 2, non atopic children shown a significant increase in the prevalence of HP serum positivity than atopic children. As for asthma, there was an higher prevalence of HP serology positive in non atopic asthmatic children group than in atopic asthmatics. On the contrary, the prevalence of positive HP serology was not significantly different between atopic and non atopic children affected by dermatitis, urticaria, and rhinitis. The present data confirm an inverse association between HP positive serology and atopy in both groups. However, the higher prevalence of positive HP serology was observed in non atopic asthmatics children than in atopic asthmatics. We could speculate that HP infection can favour non-atopic asthma onset.
Assuntos
Asma/microbiologia , Infecções por Helicobacter/imunologia , Helicobacter pylori , Hipersensibilidade/microbiologia , Anticorpos Antibacterianos/sangue , Criança , Pré-Escolar , Feminino , Helicobacter pylori/imunologia , Humanos , Lactente , Interleucina-10/biossíntese , MasculinoRESUMO
Recently, there has been considerable interest in the relationship between allergic and autoimmune diseases. We evaluated the prevalence of thyroid autoimmunity in 566 children affected by atopic dermatitis (AD), urticaria, rhinitis, chronic cough, and asthma. Our results suggest that allergy and autoimmunity can be two potential outcomes of dysregulated immunity. It is tempting to speculate that NK Th2 cells can favour asthma onset and at the same time improve thyroid autoimmunity.
Assuntos
Hipersensibilidade/complicações , Glândula Tireoide/imunologia , Tireoidite Autoimune/etiologia , Adolescente , Autoimunidade , Criança , Pré-Escolar , Feminino , Humanos , Células Matadoras Naturais/fisiologia , Masculino , Fatores de RiscoRESUMO
Highly mesoporous activated carbons (ACs) with a mesopore fraction ranging from 42 to 73% were obtained by activation of rice straw (RS) with ortho-phosphoric acid (PA). Due to such a high mesoporosity, these ACs can be successfully used for pollutant removal in aqueous phase. The ACs were prepared at activation temperatures (T) ranging from 350 to 500 degrees C, using PA to RS weight ratios (R) from 0 to 1.6 and activation times from 0 to 2 h. They were characterised by nitrogen adsorption at -196 degrees C, SEM-EDX, and methylene blue adsorption. RS is a very heterogeneous material with a variable content of mineral matter: using the product of activated carbon yield multiplied by surface area (CxS(BET)) as the performance criterion, the best AC was produced at T=450 degrees C and R>or=1. These conditions lead to S(BET) higher than 500 m(2) g(-1) and a CxS(BET) around 270 m(2) g(-1).
Assuntos
Carvão Vegetal/química , Oryza/química , Ácidos Fosfóricos/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Azul de Metileno/isolamento & purificação , Nitrogênio/isolamento & purificação , Caules de Planta , Porosidade , TemperaturaRESUMO
Tannin-based rigid foams of different bulk densities and their carbonized counterparts were investigated for the first time by X-ray microtomography. This method allowed acquisition of three-dimensional pictures of such highly porous materials. Through mathematical treatment of the images, extremely useful physical characteristics such as porosity, fraction of open cells, connectivity, tortuosity, and pore-size distribution were determined as a function of the foam's density. The obtained information was compared with independent data derived from pycnometry measurements and scanning electron microscope image analysis. The agreement was shown to be acceptable in the limit of the accuracy of the laboratory microtomograph (4 microm). Moreover, recalculating properties like permeability were shown to be quite possible based on the results of standard microtomography data.
RESUMO
Tannin-based rigid foams, prepared from 95% natural material, are suggested for replacing synthetic phenol-formaldehyde foams in various applications. For that purpose, a few physical properties were measured and reported here: resistance to fire and chemicals, absorption of various liquids, permeability, thermal conductivity and mechanical (compressive and tensile) strength. Modifying the composition through the use of boric and/or phosphoric acid allowed substantial increase of fire resistance. The materials were also found to present good resistance to strong acid and bases, and to solvents. High affinity for water, but limited one for organic liquids, was also evidenced. Finally, slightly anisotropic mechanical properties were measured. The materials present a brittle behaviour, whether tested in compression or traction; nevertheless, their strengths, as well as their thermal conductivities, are fully comparable with those of their phenolic counterparts. We show that such materials of vegetable origins can compete with synthetic ones for most of traditional applications.
Assuntos
Materiais de Construção/análise , Teste de Materiais , Taninos/química , Absorção , Fenômenos Biomecânicos , Força Compressiva , Incêndios , Permeabilidade , Porosidade , Propriedades de Superfície , Temperatura , Fatores de TempoRESUMO
OBJECTIVE: To describe serum and urinary hormones, androgens metabolites and testosterone/epitestosterone ratio profiles after testosterone administration in male hypogonadal volunteers, and to evaluate their possible usefulness in detecting doping with testosterone in treated hypogonadal athletes. DESIGN: Controlled open label design vs placebo; pharmacokinetic study. PARTICIPANTS: Ten male volunteers affected by severe hypogonadism (serum testosterone <2.31 ng/ml). INTERVENTIONS AND MAIN OUTCOME MEASURES: Serum and urinary parameters were evaluated, by radioimmunoassay and gas chromatography-mass spectrometry, before and at different time points for 7/3 weeks after a single administration of testosterone enanthate (250 mg) or placebo, respectively. RESULTS: As partially known, testosterone administration increased, with great individual variability, urinary concentrations of glucuronide testosterone, androsterone, etiocholanolone, 5alpha-androstane- 3alpha,17beta-diol, 5beta-androstane-3alpha,17beta-diol, testosterone/ epitestosterone and testosterone/LH ratios; and decreased epitestosterone and 5alpha-androstane-3beta,17beta-diol/5beta-androstane- 3alpha,17beta-diol ratio. Serum testosterone and dihydrotestosterone increased in all volunteers, and concentrations higher than the upper reference limits were observed in many volunteers until 2 weeks after testosterone administration. CONCLUSION: Whereas the observed prolonged hyperandrogenism partially limited data interpretation, the report ed characteristics of variation of urinary parameters might be used to suspect testosterone misuse in hypogonadal athletes treated with testosterone enanthate. In this sense, while the actual threshold for tes tos terone/epites tos ter one ratio was confirmed to be of reduced usefulness, we suggest a contemporary evaluation of whole urinary androgen metabolites profile and serum androgens, at specific time points after testosterone enanthate administration. Moreover, an adequate tailoring of treatment, to avoid transitory hyperandrogenism, is highly advisable. Further studies on strategies for detecting doping with testosterone in hypogonadal athletes are warranted.
Assuntos
Atletas , Dopagem Esportivo , Hormônios/sangue , Hormônios/urina , Hipogonadismo/tratamento farmacológico , Testosterona/análogos & derivados , Adulto , Hormônios/metabolismo , Humanos , Hipogonadismo/sangue , Hipogonadismo/metabolismo , Hipogonadismo/urina , Injeções Intramusculares , Masculino , Placebos , Testosterona/administração & dosagem , Testosterona/metabolismo , Testosterona/urina , Adulto JovemRESUMO
Effects of both pre-treatment and number of steps in KOH activation of raw rice straw (RS) on textural and adsorption properties of RS-derived activated carbons (ACs) were investigated. Three pre-treatment protocols were tested: mechanical, chemical by NaOH pulping, and a combination of both. Activation of RS-based materials was investigated, at a constant temperature of 800 degrees C, according to two ways: a 1-step simultaneous carbonisation-activation with KOH, and a 2-steps process: carbonisation followed by activation by KOH. 2-Steps KOH activation was more efficient in producing activated carbons with high surface areas and high methylene blue adsorption than 1-step KOH activation. Additionally, 2-steps KOH activation increased the yield of activated carbons having moderate ash content (8-14%). Surface areas as high as 1917 m(2)/g were obtained when the combined mechanical-chemical pre-treatment method and a 2-steps activation process were carried out.
Assuntos
Carvão Vegetal/síntese química , Química Orgânica/métodos , Hidróxidos/química , Oryza/química , Compostos de Potássio/química , Adsorção , Carvão Vegetal/química , Cinética , Lignina/química , Azul de Metileno/química , Azul de Metileno/isolamento & purificação , Nitrogênio/química , Porosidade , Propriedades de Superfície , TemperaturaRESUMO
Ferric chloride forced hydrolysis is shown to be a good method for increasing the iron content of activated carbons (ACs). Iron content increased linearly with hydrolysis time, and ACs with iron content as high as 9.4wt.% at 24h hydrolysis time could be prepared. The increase in iron content did not produce any modification in the textural parameters determined by nitrogen adsorption at 77K. Iron-based nanoparticles, homogeneous in size and well-dispersed in the carbon matrix, were obtained. Nanoparticles forming iron (hydr)oxide agglomerates at the outer surface of the carbon grains at hydrolysis times higher than 6h were also produced. The AC obtained after 6h of ferric chloride forced hydrolysis removed 94% of the arsenic present in a groundwater from the State of Chihuahua (Mexico), whereas the commercial AC used as precursor allowed the removal of only 14%. The lower performance in arsenic removal observed for AC prepared using long forced hydrolysis time (24h) is probably due to the existence of iron (hydr)oxides nanoparticles agglomerates, which once hydrated could prevent diffusion of arsenate (HAsO(4)(-)) towards the inner surface of the AC grain.
Assuntos
Arsênio/isolamento & purificação , Carvão Vegetal/química , Compostos Férricos/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cloretos , Água Doce , Hidrólise , Ferro , MéxicoRESUMO
Arsenic removal from natural well water from the state of Chihuahua (Mexico) is investigated by adsorption using a commercial activated carbon (AC). The latter is used as such, or after oxidation by several chemicals in aqueous solution: nitric acid, hydrogen peroxide, and ammonium persulphate. Raw and oxidised activated carbons are fully characterised (elementary analysis, surface chemistry, pore texture parameters, pH(ZC), and TEM observation). Adsorption of As is measured in the aforementioned water, containing ca. 300 ppb of arsenic: removal of As is poor with the raw AC, and only the most oxidised carbons exhibit higher performances. By contrast, iron-doped ACs are much more efficient for that purpose, though their As uptake strongly depends on their preparation conditions: a number of samples were synthesised by impregnation of raw and oxidised ACs with HCl aqueous solutions of either FeCl(3) or FeCl(2) at various concentrations and various pH. It is shown that iron(II) chloride is better for obtaining high iron contents in the resultant ACs (up to 8.34 wt.%), leading to high As uptake, close to 0.036 mg As/g C. In these conditions, 100% of the As initially present in the natural well water is removed, as soon as the Fe content of the adsorbent is higher than 2 wt.%.
Assuntos
Arsênio/isolamento & purificação , Carvão Vegetal/química , Ferro/química , Poluentes Químicos da Água/isolamento & purificação , Abastecimento de Água/análise , Adsorção , Compostos Férricos/química , Compostos Ferrosos/química , Água Doce , México , Abastecimento de Água/normasRESUMO
The problems of valorisation of particleboard wastes on one hand, and contamination of aqueous effluents by phenolic compounds on the other hand, are simultaneously considered in this work. Preparation of activated carbons from a two steps thermo-chemical process, formerly designed for generating combustible gases, is suggested. The resultant carbonaceous residue is activated with steam at 800 degrees C. Depending on the preparation conditions, surface areas within the range 800-1300 m(2)/g are obtained, close to that of a commercial activated carbon (CAC) specially designed for water treatment and used as a reference material. The present work shows that particleboard waste-derived activated carbons (WAC) are efficient adsorbents for the removal of phenol from aqueous solutions, with maximum measured capacities close to 500 mg/g. However, most of times, the adsorption capacities are slightly lower than that of the commercial material in the same conditions, i.e., at equilibrium phenol concentrations below 300 ppm. Given the extremely low cost of activated carbons prepared from particleboard waste, it should not be a problem to use it in somewhat higher amounts than what is required with a more expensive commercial material. Phenol adsorption isotherms at 298 K were correctly fitted by various equations modelling type I and type II isotherms for CAC and WAC, respectively. Phenol adsorption isotherms of type II were justified by a 3-stages adsorption mechanism.
Assuntos
Carvão Vegetal/síntese química , Conservação dos Recursos Naturais/métodos , Fenóis/isolamento & purificação , Eliminação de Resíduos/métodos , Poluentes Químicos da Água/isolamento & purificação , Madeira/química , Adsorção , Resíduos Industriais/prevenção & controleRESUMO
Prostaglandins modulate the hypothalamus-pituitary-adrenal and -gonadal axis pathways. We explored the effects of a single course of treatment with acetylsalicylic acid (ASA), an inhibitor of prostaglandin synthesis, on the steroid milieu in athletes. Morning plasma cortisol (F), dehydroepiandrosterone sulphate, free-testosterone, testosterone (T) and their ratios were evaluated before and after the administration of either ASA or placebo in twelve male athletes, when affected by minor musculoskeletal trauma and, as control, after a five/six week wash-out in healthy conditions respectively. One tablet of ASA (800 mg), or placebo, was administered two times daily for 10 days during treatment. All the volunteers suspended exercise training during treatment. The results revealed that compared to placebo, plasma F was significantly lower after ASA treatment (p = 0.023). Furthermore, the comparison of hormone's absolute and percentage of variations (Delta and Delta%) between ASA and placebo treatment showed significant differences respectively for DeltaF (p = 0.045), for DeltaT (p = 0.047), for DeltaT/F (p = 0.042), for DeltaF% (p = 0.04) and for DeltaT% (p = 0.049). Our data suggest that in comparison to placebo, a short-term ASA treatment is able to influence the plasma steroid milieu in athletes. Due to the observed variability of the individual hormonal patterns, further research is required to substantiate these findings.