943 resultados para Absorption of water


Relevância:

100.00% 100.00%

Publicador:

Resumo:

Objectives: To develop an epirubicin-loaded, water-soluble mucoadhesive gels that have the correct rheological properties to facilitate their delivery into the bladder via a catheter, while allowing for their spread across the bladder wall with limited expansion of the bladder and increasing the retention of epirubicin in the bladder and flushing with urine.

Methods: Epirubicin-loaded hydroxyl ethyl cellulose (HEC) and hydroxy propyl methyl cellulose (HPMC) gels were manufactured and tested for their rheological properties. Their ability to be pushed through a catheter was also assessed as was their in-vitro drug release, spreading in a bladder and retention of epirubicin after flushing with simulated urine.

Key findings: Epirubicin drug release was viscosity-dependent. The 1 and 1.5% HEC gels and the 1, 1.5 and 2% HPMC gels had the correct viscosity to be administered through a model catheter and spread evenly across the bladder wall under the pressure of the detrusor muscle. The epirubicin-loaded gels had an increased retention time in the bladder when compared with a standard intravesical solution of epirubicin, even after successive flushes with simulated urine.

Conclusion: The increased retention of epirubicin in the bladder by the HEC and HPMC gels warrant further investigation, using an in-vivo model, to assess their potential for use as treatment for non-muscle-invasive bladder cancer.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Herein, we report the densities and speeds of sound in binary mixtures of three hydrophobic and one hydrophilic ionic liquids: 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [C4mim][NTf2], 1-butyl-1-methylpyrrolidinium bis[(trifluoromethyl)sulfonyl]imide, [C4mpyr][NTf2], 1-propyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, [C3mim][NTf2] and 1-ethyl-3-methylimidazolium thiocyanate, [C2mim][SCN], with water at 298.15 K and 0.1 MPa. The concentration range of water, which encompassed relatively small values well below the saturation point, is often regarded as an impurity for hydrophobic ionic liquids. On the basis of experimental results the molar volume, adiabatic molar compressibility, partial molar volume and apparent molar volume, as well as, partial molar and apparent molar isentropic compressibility properties were then calculated. Interesting results are obtained using the solutions based on the hydrophilic [C2mim][SCN], since these mixtures are characterized by relatively low density and high values of speed of sound. Furthermore, the partial molar volumes and partial molar adiabatic compressibilities of water in solution with [C2mim][SCN] are the lowest among the investigated in mixtures with ionic liquids. However, in the case of the hydrophobic ionic liquid solutions, only small differences are observed for molar adiabatic compressibilities with the change of the cation structure, i.e. for water + [C4mim][NTf2] or + [C4mpyr][NTf2]. A more pronounced difference has been observed for the partial molar compressibility of water in solutions with these two ionic liquids.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The use of semiconductor photocatalysis for treatment of water and air has been a topic of intense research activity over the past 20 years. This chapter provides a review of this highly effective technology. The fundamental processes involved in the technique are initially detailed with a discussion of some recent novel concepts in photocatalysis. A range of applications of water and air treatment are subsequently described with examples of mechanistic description of the major breakdown pathways of some key compounds. Examples of large-scale water treatment applications are also discussed.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The title process comprises admixing cellulose with an ionic liq. capable of solvating or dissolving at least some of the cellulose, the ionic liq. being a compd. comprised solely of cations and anions (e.g., 1-ethyl-3-methylimidazolium sulfate) and which exists in a liq. state at a temp. at or below 150°, and in which the anions are selected from sulfate, hydrogen sulfate and nitrate; and treating the resulting solvate or soln. with an acid in the presence of water, the acid having a pKa in water of less than 2 at 25°. [on SciFinder(R)]

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The title process comprises admixing cellulose with an ionic liq. capable of solvating or dissolving at least some of the cellulose, the ionic liq. being a compd. comprised solely of cations and anions (e.g., 1-ethyl-3-methylimidazolium sulfate) and which exists in a liq. state at a temp. at or below 150°, the cations in the ionic liq. having the general formula R1Z(R2)(R3)R4: in which Z represents a nitrogen or phosphorus atom, R1 represents a Me or Et group, each of R2 and R3, which may be the same or different, is selected from C4-8alkyl, optionally-substituted benzyl, optionally-substituted Ph, and C5-7cycloalkyl, and R4 represents C1-8 alkyl, optionally-substituted benzyl, optionally-substituted Ph or C5-7cyclohexyl; in which the optional substituents on a benzyl or Ph ring are one, two or three substituents selected from C1-4alkyl or alkoxy groups, halogen atoms and nitro groups; and treating the resulting solvate or soln. with an acid in the presence of water, the acid having a pKa in water of less than 2 at 25°. [on SciFinder(R)]

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The growth of the construction industry worldwide poses a serious concern on the sustainability of the building material production chain, mainly due to the carbon emissions related to the production of Portland cement. On the other hand, valuable materials from waste streams, particularly from the metallurgical industry, are not used at their full potential. Alkali activated concrete (AAC) has emerged in the last years as a promising alternative to traditional Portland cement based concrete for some applications. However, despite showing remarkable strength and durability potential, its utilisation is not widespread, mainly due to the lack of broadly accepted standards for the selection of suitable mix recipes fulfilling design requirements, in particular workability, setting time and strength. In this paper, a contribution towards the design development of AAC synthetized from pulverised fuel ash (60%) and ground granulated blast furnace slag (40%) activated with a solution of sodium hydroxide and sodium silicate is proposed. Results from a first batch of mixes indicated that water content influences the setting time and that paste content is a key parameter for controlling strength development and workability. The investigation indicated that, for the given raw materials and activator compositions, a minimum water to solid (w/s) ratio of 0.37 was needed for an initial setting time of about 1 hour. Further work with paste content in the range of 30% to 33% determined the relationship between workability and strength development and w/s ratio and paste content. Strengths in the range of 50 - 60 MPa were achieved.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The coast of the Bulgarian Black Sea is a popular summer holiday destination. The Dam of Iskar is the largest artificial dam in Bulgaria, with a capacity of 675 million m3. It is the main source of tap water for the capital Sofia and for irrigating the surrounding valley. There is a close relationship between the quality of aquatic ecosystems and human health as many infections are waterborne. Rapid molecular methods for the analysis of highly pathogenic bacteria have been developed for monitoring quality. Mycobacterial species can be isolated from waste, surface, recreational, ground and tap waters and human pathogenicity of nontuberculose mycobacteria (NTM) is well recognized. The objective of our study was to perform molecular analysis for key-pathogens, with a focus on mycobacteria, in water samples collected from the Black Sea and the Dam of Iskar. In a two year period, 38 water samples were collected-24 from the Dam of Iskar and 14 from the Black Sea coastal zone. Fifty liter water samples were concentrated by ultrafiltration. Molecular analysis for 15 pathogens, including all species of genus Mycobacterium was performed. Our results showed presence of Vibrio spp. in the Black Sea. Rotavirus A was also identified in four samples from the Dam of Iskar. Toxigenic Escherichia coli was present in both locations, based on markers for stx1 and stx2 genes. No detectable amounts of Cryptosporidium were detected in either location using immunomagnetic separation and fluorescence microscopy. Furthermore, mass spectrometry analyses did not detect key cyanobacterial toxins. On the basis of the results obtained we can conclude that for the period 2012-2014 no Mycobacterium species were present in the water samples. During the study period no cases of waterborne infections were reported.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The shallow water kelp Laminaria digitata, abundant in coastal zones of the North Atlantic, is exposed to a range of hydrodynamic environments that makes it ideal for assessing the role of water motion on their growth rate. Here we quantify the growth of L. digitata, as a factor of blade and stipe elongation, at sites adjacent to Strangford Lough, Northern Ireland under different hydrodynamic conditions over a one year period. A modelling approach was used to numerically determine both the temporal and spatial variability of the hydrodynamic environment. Ambient seawater nutrient concentrations, temperature and irradiance were measured as well as the internal nutrient status of the L. digitata populations. Kelp populations growing in the greatest and lowest water motion showed the lowest growth rates. Differences observed in growth rate could not be attributed to seawater nutrient availability, temperature or light. The internal nutrient status also suggested no influence on the observed differences in growth rate. Therefore if there are minimal differences in light, temperature and nutrients between sites, then populations of L. digitata exposed to different water motions are likely to exhibit different growth rates. It is suggested that the growth rate differences observed were a function of water motion with the possibility that, in response to the hydrodynamic forces experienced by the algal cells, L. digitata kelps in the high energy environments were putting more energy into strengthening cell walls rather than blade elongation

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Todos os sistemas aquáticos estão potencialmente expostos a alterações nos parâmetros da água em consequência de fenómenos ambientais tais como deposição ácida, lixiviação de iões dos solos e alterações climáticas. Dado que os parâmetros químicos da água estão geralmente correlacionados, é pertinente estudar os seus efeitos combinados para o biota aquático. Assim, o principal objetivo desta tese é avaliar a importância ecológica da variação simultânea dos principais parâmetros fisico-químicos da água nos parâmetros de história de vida dos crustáceos tanto na ausência como na presença de metais. Foram estudados os seguintes parâmetros: dureza (0.5 - 3.5 mM), alcalinidade (0.3 - 2.3 mM), pH (5.7 - 9.0) e temperatura (13 - 30ºC). A Daphnia magna foi usada como espécie modelo representando os crustáceos aquáticos. A variação simultânea da dureza e alcalinidade afetou significativamente o crescimento, reprodução e crescimento populacional de Daphnia; no entanto, os efeitos da dureza excederam os efeitos da alcalinidade. Pareceu haver interação entre a dureza e alcalinidade na reprodução dos dafnídeos, o que sugere que os efeitos da variação da dureza para Daphnia e provavelmente outros crustáceos poderão depender do nível de alcalinidade. O pH e dureza da água exerceram efeitos combinados para Daphnia, sendo os efeitos do pH mais pronunciados do que os efeitos da dureza. A diminuição do pH reduziu a sobrevivência, crescimento, reprodução, taxa de ingestão e crescimento populacional dos dafnídeos. No entanto, os efeitos do pH baixo foram mais adversos a baixa dureza, o que sugere uma interação entre estes parâmetros. Assim, a diminuição do pH em lagos de água mole pode ser um estressor determinante para os crustáceos sensíveis à acidez, ameaçando a sua sobrevivência e, consequentemente, afetando a estrutura das cadeias alimentares aquáticas. A temperatura e a química da água (dureza e alcalinidade) interagiram entre si nos parâmetros de história de vida de Daphnia; no entanto, os efeitos da temperatura excederam os efeitos da química da água. De um modo geral, temperaturas extremas reduziram o crescimento, reprodução e, consequentemente, o crescimento populacional de Daphnia. Os efeitos do aumento da temperatura foram mais adversos a baixa dureza e alcalinidade, aumentando a preocupação com os efeitos ecológicos do aquecimento global em águas moles. A dureza e alcalinidade da água também desempenharam um papel importante na toxicidade aguda e subletal (inibição da ingestão) dos metais para Daphnia. A diminuição da dureza aumentou a toxicidade aguda do zinco. Por outro lado, a diminuição da alcalinidade aumentou a toxicidade aguda e subletal do cobre, mas reduziu a toxicidade subletal do zinco, tornando evidente o importante papel da alcalinidade na toxicidade subletal dos metais para Daphnia. Globalmente, os parâmetros fisico-químicos da água parecem interagir entre si, afetando os parâmetros de história de vida e o crescimento populacional de Daphnia e também afetam a toxicidade dos metais. Em particular, a baixa dureza agrava os efeitos adversos da diminuição do pH, aumento da temperatura e toxicidade dos metais, o que aumenta a preocupação com os efeitos ecológicos da sua variação simultânea sobre os crustáceos e, portanto, sobre as cadeias alimentares aquáticas.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The fast increase in the energy’s price has brought a growing concern about the highly expensive task of transporting water. By creating an hydraulic model of the Water Supply System’s (WSS) network and predicting its behaviour, it is possible to take advantage of the energy’s tariffs, reducing the total cost on pumping activities. This thesis was developed, in association with a technology transfer project called the E-Pumping. It focuses on finding a flexible supervision and control strategy, adaptable to any existent Water Supply System (WSS), as well as forecasting the water demand on a time period chosen by the end user, so that the pumping actions could be planned to an optimum schedule, that minimizes the total operational cost. The OPC protocol, associated to a MySQL database were used to develop a flexible tool of supervision and control, due to their adaptability to function with equipments from various manufacturers, being another integrated modular part of the E-Pumping project. Furthermore, in this thesis, through the study and performance tests of several statistical models based on time series, specifically applied to this problem, a forecasting tool adaptable to any station, and whose model parameters are automatically refreshed at runtime, was developed and added to the project as another module. Both the aforementioned modules were later integrated with an Graphical User Interface (GUI) and installed in a pilot application at the ADDP’s network. The implementation of this software on WSSs across the country will reduce the water supply companies’ running costs, improving their market competition and, ultimately, lowering the water price to the end costumer.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Tese de doutoramento, Química (Química Tecnológica), Universidade de Lisboa, Faculdade de Ciências, 2014