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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Preparation and characterisation of pheroid vesicles / Charlene Ethel Uys

Uys, Charlene Ethel January 2006 (has links)
Pheroid is a patented system comprising of a unique submicron emulsion type formulation. Pheroid vesicles consist mainly of plant and essential fatty acids and can entrap, transport and deliver pharmacologically active compounds and other useful molecules. The aim of this study was to show that a modulation of components and parameters is necessary to obtain the optimum formula to be used in pharmaceutical preparations. Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions (Bjerregaard et al., 2001:23). Careful consideration was given to the apparatus used during the processing along with the ratios of the various components added to the formulation and the storage conditions of the Pheroid vesicles. A preliminary study was performed to optimize the most accurate processing parameters during emulsification. The effect of emulsification rate and time, the temperature of the aqueous phase, the number of days the water phase were gassed, the concentration of the surfactant, cremophor® RH 40, used and the concentration of Vitamin F Ethyl Ester CLR added to the oil phase of the o/w emulsion has been studied. Quantification of the mean particle size, zeta potential, turbidity, pH and current values were used to characterize the emulsions. The samples were characterised after 1, 2, 3, 7, 14, 21 and 28 days of storage. The emulsions were also characterised with confocal laser scanning microscopy (CLSM) to measure the number and size and size distribution of the vesicles. After determination of the processing variables influencing the emulsion stability an accelerated stability test was conducted on a final formula. In the present study, accelerated stability testing employing elevated temperatures and relative humidity were used with good accuracy to predict long-term stability of an o/w emulsion kept at both 5 and 25 OC with 60 % relative humidity and 40 OC with 75 % relative humidity. The results of the stability tests were presented in histograms of the physical properties 24 hours, 1 month, 2 months and 3 months after preparation of the emulsion. It was concluded that Pheroid vesicles demonstrate much potential as a drug delivery system. The high stability of this formula allows its use in a wide variety of applications in the pharmaceutical industry. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
272

Comparison of airborne particulate exposure in two platinum refining process areas / Z. Selenati–Dreyer

Selenati-Dreyer, Zoe January 2010 (has links)
The aims and objectives: The aims and objectives of this study were to characterize and compare the airborne particulate matter in the tankhouse and crusher areas of a base metal refinery sampled with two separate methods, in terms of mass concentration, nickel content, and particle size distribution. Methods: Area sampling was conducted in the two areas. Two methods were applied to collect particulate samples. The first is a multi–stage virtual impactor, the Respicon, which was used to determine the three critical particle fractions (inhalable, thoracic and respirable). The NIOSH 7300 method determined the particle concentration and nickel percentage present in each fraction. Using formulas provided by the manufacturers two additional particle–size fractions (extra–thoracic and trachea–bronchial) could be calculated. The second was based on the standard NIOSH 0500 method, which determined particle size distribution depicted as cumulative percentages. The samples were analyzed using laser scattering instrumentation. Results: In the tankhouse the highest level of exposure was to particles bigger than 10 um, with the highest nickel percentage also falling into this range. However, high nickel percentages were present in all three cut–off sizes (4 um, 10 um and > 10 um). The particle concentration for the crusher area was the highest for particulates bigger than 10 um, with the highest nickel percentage present in this fraction. After comparing the tankhouse and crusher areas, it is clear that the particle concentration is much higher in the crusher area according to all sampling methods used. The nickel content present in the analysis of these areas is of great concern. Conclusion: With the knowledge obtained through this research one hopes to establish a basis for particle size sampling in the platinum mining industry. This may lead to the development of health based OEL's and reflect a more accurate evaluation of workers particulate exposure. This information will give a greater understanding of health risks workers are exposed to. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.
273

Preparation and characterisation of pheroid vesicles / Charlene Ethel Uys

Uys, Charlene Ethel January 2006 (has links)
Pheroid is a patented system comprising of a unique submicron emulsion type formulation. Pheroid vesicles consist mainly of plant and essential fatty acids and can entrap, transport and deliver pharmacologically active compounds and other useful molecules. The aim of this study was to show that a modulation of components and parameters is necessary to obtain the optimum formula to be used in pharmaceutical preparations. Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions (Bjerregaard et al., 2001:23). Careful consideration was given to the apparatus used during the processing along with the ratios of the various components added to the formulation and the storage conditions of the Pheroid vesicles. A preliminary study was performed to optimize the most accurate processing parameters during emulsification. The effect of emulsification rate and time, the temperature of the aqueous phase, the number of days the water phase were gassed, the concentration of the surfactant, cremophor® RH 40, used and the concentration of Vitamin F Ethyl Ester CLR added to the oil phase of the o/w emulsion has been studied. Quantification of the mean particle size, zeta potential, turbidity, pH and current values were used to characterize the emulsions. The samples were characterised after 1, 2, 3, 7, 14, 21 and 28 days of storage. The emulsions were also characterised with confocal laser scanning microscopy (CLSM) to measure the number and size and size distribution of the vesicles. After determination of the processing variables influencing the emulsion stability an accelerated stability test was conducted on a final formula. In the present study, accelerated stability testing employing elevated temperatures and relative humidity were used with good accuracy to predict long-term stability of an o/w emulsion kept at both 5 and 25 OC with 60 % relative humidity and 40 OC with 75 % relative humidity. The results of the stability tests were presented in histograms of the physical properties 24 hours, 1 month, 2 months and 3 months after preparation of the emulsion. It was concluded that Pheroid vesicles demonstrate much potential as a drug delivery system. The high stability of this formula allows its use in a wide variety of applications in the pharmaceutical industry. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.
274

Comparison of airborne particulate exposure in two platinum refining process areas / Z. Selenati–Dreyer

Selenati-Dreyer, Zoe January 2010 (has links)
The aims and objectives: The aims and objectives of this study were to characterize and compare the airborne particulate matter in the tankhouse and crusher areas of a base metal refinery sampled with two separate methods, in terms of mass concentration, nickel content, and particle size distribution. Methods: Area sampling was conducted in the two areas. Two methods were applied to collect particulate samples. The first is a multi–stage virtual impactor, the Respicon, which was used to determine the three critical particle fractions (inhalable, thoracic and respirable). The NIOSH 7300 method determined the particle concentration and nickel percentage present in each fraction. Using formulas provided by the manufacturers two additional particle–size fractions (extra–thoracic and trachea–bronchial) could be calculated. The second was based on the standard NIOSH 0500 method, which determined particle size distribution depicted as cumulative percentages. The samples were analyzed using laser scattering instrumentation. Results: In the tankhouse the highest level of exposure was to particles bigger than 10 um, with the highest nickel percentage also falling into this range. However, high nickel percentages were present in all three cut–off sizes (4 um, 10 um and > 10 um). The particle concentration for the crusher area was the highest for particulates bigger than 10 um, with the highest nickel percentage present in this fraction. After comparing the tankhouse and crusher areas, it is clear that the particle concentration is much higher in the crusher area according to all sampling methods used. The nickel content present in the analysis of these areas is of great concern. Conclusion: With the knowledge obtained through this research one hopes to establish a basis for particle size sampling in the platinum mining industry. This may lead to the development of health based OEL's and reflect a more accurate evaluation of workers particulate exposure. This information will give a greater understanding of health risks workers are exposed to. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011.
275

Influence of flame retardant additives on the processing characteristics and physical properties of ABS

Seddon, Richard January 2000 (has links)
Antimony trioxide (Sb203) and halogenated additives are used together in flameretarded formulations due to their synergistic retardant properties. A study has been made to determine the effects of adding different grades of Sb203 (dSD particle sizes 0.11 um, 0.52um and 1.31 um) into ABS polymer either alone or with commercial brominated materials (BTBPE, TBBA, DBDPO) and an experimental bromine grade (sDBDPO). The Sb20 3 was added at 4wt% loadings and the bromines at 20wt% loadings. The results consider the influence of the additives on processing, mechanical, morphological and flame retardant properties. All compounds were produced using a twin-screw co-rotating extruder and then an injection moulder was used to mould notched impact (falling weight testing), flexural, LOI and UL-94 flame test bars. Samples of all the compounded formulations were titrated to determine Sb20 3 and Br contents. Fracture surface, morphology, size and dispersion analysis was carried out using both SEM and TEM equipment. Osmium tetroxide (OS04) staining was used to determine relative locations of filler particles and polybutadiene phase. Additions of the different antimony trioxide grades showed that the 0.52um and 1.31 um grades lowered impact energy absorption (-25 to -30%) when added at 4wt% loading. The use of a sub-micron size grade (0.1 um) did not significantly lower impact properties (-3%) and had similarly small effects on the flexural modulus and flexural strength. Additions of the brominated materials had much greater effects causing large reductions in impact properties (-20 to :70%). The presence of the bromines generally increased flexural modulus and lowered flexural strength with the exception of TB BA, which increased both modulus and strength. Compounds containing both 1.31 um Sb203 and bromines suffered a further reduction in impact energies, with the bromine properties dominating. Using the 0.1 um Sb20 3 grade again improved impact and flexural properties compared to the 1.31 um grade. The 0.1 um grade resulted in improvements in fire resistance as measured by the UL-94 properties when used with all bromine grades.
276

The impact of airway-irritating exposure and wet work on subjects with allergy or other sensitivity : epidemiology and mechanisms /

Wiebert, Pernilla, January 2007 (has links)
Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 5 uppsatser.
277

Metals in urban playground soils : distribution and bioaccessibility /

Ljung, Karin, January 2006 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2006. / Härtill 4 uppsatser.
278

Use of sugarcane trash for solid biofuel production: physicochemical characterization and influence of storage time / Uso do palhiço da cana-de-açúcar para a produção de biocombustíveis sólidos: caracterização físico-química e influência do tempo de estocagem

Nakashima, Gabriela Tami 29 April 2016 (has links)
Submitted by Milena Rubi (milenarubi@ufscar.br) on 2017-08-09T12:48:03Z No. of bitstreams: 1 NAKASHIMA_Gabriela_2016.pdf: 18948386 bytes, checksum: c4adf2165784091a5371108a8c2bd529 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2017-08-09T12:48:12Z (GMT) No. of bitstreams: 1 NAKASHIMA_Gabriela_2016.pdf: 18948386 bytes, checksum: c4adf2165784091a5371108a8c2bd529 (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2017-08-09T12:48:18Z (GMT) No. of bitstreams: 1 NAKASHIMA_Gabriela_2016.pdf: 18948386 bytes, checksum: c4adf2165784091a5371108a8c2bd529 (MD5) / Made available in DSpace on 2017-08-09T12:48:26Z (GMT). No. of bitstreams: 1 NAKASHIMA_Gabriela_2016.pdf: 18948386 bytes, checksum: c4adf2165784091a5371108a8c2bd529 (MD5) Previous issue date: 2016-04-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / In the sugarcane plantation it was common to use fire to facilitate the cutting and harvesting of sugarcane. However, Law 11,241 / 02 in São Paulo State provides the gradual elimination of this straw burning of sugarcane. The largest producer of sugarcane in Brazil is the São Paulo State, which has about 4.7 million hectares of planted area. It is estimated that one hectare produces about 14 tons of trash. Therefore, the mills have been trying to incorporate this trash in burning with the bagasse for power generation. However, high concentrations of mineral impurities are impossible its use for energy purposes. The aim of the study was to investigate the influence of storage time and particle size in the physicochemical characterization of the sugarcane trash. It was used the sugarcane trash inside and outside of the bale collected at different storage time (0, 1 and 2 years). The collected material was separated into four different particle sizes (> 0.420mm, 0.250-0.420mm, < 0.250mm and mix). The analyzes involved particle size distribution, proximate analysis, the high heating value (HHV), the chemical analysis of the components of the ashes, the images in the Scanning Electron Microscope (SEM), the Klason lignin content, the holocellulose content and extractives. There were variations in the results of the ash content with different particle sizes. It was observed a higher concentration of mineral impurities in smaller particles (< 0.250mm). The HHV varied from 15.9 to 18.3 MJ.kg-1 and showed no statistical difference for the treatments. The results indicate that the sugarcane trash presents problems related to mineral impurities which constrain its use as a solid fuel in the industry. The particle size interferes in their physicochemical characteristics. The trash can be stored in field and the time storage did not affect the quality for use as solid biofuel. / No manejo da cana-de-açúcar era comum a utilização do fogo para facilitar o corte e colheita da cana. No entanto, a Lei 11.241/02 do estado de São Paulo prevê a eliminação gradual da queima da palha da cana-de-açúcar. O maior produtor de cana-de-açúcar do Brasil é o estado de São Paulo, que possui aproximadamente 4,7 milhões de hectares de área plantada. É estimado que 1 hectare produza cerca de 14 toneladas de palha. Logo, as usinas vêm tentando incorporar esta palha na queima para geração de energia, juntamente com o bagaço. Porém, as altas concentrações de impurezas minerais estão impossibilitando seu uso para fins energéticos. O trabalho teve como objetivo o estudo da influência do tempo de estocagem e da granulometria na caracterização físico-química do palhiço da cana-de-açúcar. Foi utilizado o palhiço de canade-açúcar da superfície e do interior do fardo coletados em diferentes períodos de estocagem, 0, 1 e 2 anos. O material coletado foi separado em 4 granulometrias diferentes (> 0,420mm, 0,250-0,420mm, < 0,250mm e mix). As análises realizadas foram a distribuição granulométrica, a análise imediata, o poder calorífico superior (PCS), a análise química dos componentes das cinzas, as imagens no Microscópio Eletrônico de Varredura (MEV), o teor de lignina Klason, a holocelulose e os extrativos. Houve variações nos resultados do teor de cinzas com as diferentes granulometrias. Observou-se maior concentração de impurezas minerais nas partículas mais finas (< 0,250mm). O PCS variou entre 15,9 a 18,3 MJ.kg-1 e não apresentou diferença estatística para os tratamentos. Os resultados indicam que a palha de cana-de-açúcar apresenta problemas relacionados às impurezas minerais, que dificultam e restringem seu uso como combustível sólido na indústria. A granulometria da palha interferiu nas suas características físico-químicas. O palhiço pode ser estocado no campo e o tempo de estocagem não interferiu na qualidade para o uso como combustível sólido.
279

Synthesis of zinc oxide nanoparticles with different morphologies by wet chemistry routes

Young, Michael I. January 2016 (has links)
The objectives of this project were to synthesise semi-conducting ceramic nanoparticles including zinc oxide (ZnO) and aluminium doped zinc oxide (AZO) through a wet chemistry route to obtain nanoparticles with a controlled size and morphology. Wet chemistry methods (co-precipitation method and hydrothermal method) were used to synthesise ZnO and AZO particles. In the synthesis, various compounds and morphologies were synthesised. ZnO, Zn(OH)2 and unknown phases were co-precipitated, with only ZnO obtained following hydrothermal treatment. Morphologies ranging from platelets, flower-like, nanorods and microflowers were obtained. Particle sizes as small as 11 nm were characterised. Nanorod and nanosphere AZO particles were also synthesised with the results indicated the average grain size decreasing with increasing Al atomic content. Three orthogonal arrays were carried out to investigate the effects of the reaction parameters on the size and morphology of ZnO particles. The applicability of the orthogonal array was successful, with the optimum parameters of both hydrothermal experiments showing an increase in aspect ratio. The L/D ratio of ZnO nanorods obtained in the confirmation experiment increased to 9.4 which was larger than the ZnO synthesised using other reaction conditions (1.0 8.0). Scanning electron microscopy, transmission electron microscopy and X-ray diffraction were used to characterise the properties of the obtained particles. Morphology, crystallinity and particle size were all characterised.
280

Alteração do processo de fabricação de comprimidos de diclofenaco sódico - foco na granulação úmida / Changing the manufacturing of diclofenac sodium tablets process - focus on wet granulation

Silveira, Larissa dos Santos da January 2014 (has links)
Made available in DSpace on 2016-06-21T13:45:02Z (GMT). No. of bitstreams: 2 9.pdf: 5002800 bytes, checksum: 1aab555cfe6db1a0cf1577ab298c8017 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2014 / Made available in DSpace on 2016-07-05T22:38:04Z (GMT). No. of bitstreams: 3 9.pdf.txt: 252589 bytes, checksum: b070d500ec1baafb988fc3fbf27085c1 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) 9.pdf: 5002800 bytes, checksum: 1aab555cfe6db1a0cf1577ab298c8017 (MD5) Previous issue date: 2014 / Fundação Oswaldo Cruz. Instituto de Tecnologia em Fármacos/Farmanguinhos. Rio de Janeiro, RJ, Brasil. / O escalonamento no processo de fabricação de comprimidos é um processo complexo e ainda bastante empírico, feito por método de tentativas e erros, cujos desafios são ainda maiores quando trata-se de formulação obtida por granulação úmida. Este trabalho realizou a transposição de escala de uma formulação de comprimidos revestidos contendo diclofenaco de sódio, fármaco de ação antiinflamatória,não esteroide e inibidor não seletivo das COX 1 e 2, avaliando os fatores relevantes para a obtenção tanto de uma formulação robusta, no que diz respeito ao processo de escalonamento em si, quanto de um medicamento que atendesse às exigências legais necessárias ao registro junto ao órgão regulador.Como resultado, o medicamento originário da formulação proposta apresentou-se aprovado em todos os ensaios exigidos, inclusive mostrando-se bioequivalente ao de referência. Este resultado ratificou a importância dos trabalhos preliminares,como a caracterização do ativo e os estudos referentes aos parâmetros a serem observados na transposição de escala. Na caracterização, as análises mostraram que a forma polimórfica do diclofenaco de sódio utilizado na formulação era a anidra,forma mais solúvel do fármaco; nas etapas de transposição de escala, identificou-se problemas com a alteração dos tempos de mistura do lote experimental para o lote piloto, pois não obteve-se uma boa compressibilidade para o lote piloto. Foi verificada, nas análises do granulado, uma diferença de granulometria que poderia justificar a diferença de desempenho entre os dois lotes. Um novo piloto foi manipulado, com a manutenção dos tempos de mistura do lote experimental, sendo que, dessa forma, os resultados satisfatórios do referido lote experimental foram reproduzidos para o segundo piloto, tanto em processabilidade quanto na avaliação granulométrica e demais ensaios. / Scaling up in the tabletting process is still a rather complex and empirical process carried out by trial and error methods, whose challenges are even greater when the formulation is obtained through wet granulation. Through this work, the development of large-scale production of a formulation of coated tablets containing diclofenac sodium, an anti-inflammatory drug, non-steroidal and non-selective inhibitor of COX 1 and 2, was conducted, evaluating the relevant factors for obtaining both a robust formulation with regard to the scale-up process itself and a drug which meets the legal requirements necessary for registration with the regulatory body. As a result, the product originating from the proposed formulation passed all of the required tests, and it was also proven to be bioequivalent to the reference drug. This result confirmed the importance of preliminary work, such as the characterization of active and studies concerning the parameters to be observed in the development of largescale production. In the characterization, the analysis showed that the polymorphic form of diclofenac sodium used in formulating was the anhydrous one, the more soluble form of the drug. In the steps of the development of large-scale production, there were problems with the alteration of the mixing times from the experimental batch to the pilot batch, as there was no good compressibility for the pilot batch. In the analyzes of the granulate, a difference of particle size was identified. It could explain the difference in performance between the two batches. Therefore, a new pilot batch was manipulated, with the maintenance of the mixing times of the experimental batch, and thus satisfactory results of the experimental batch were reproduced for the second pilot batch, regarding processability, particle assessment and other tests.

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