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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.
1051

Single step production of nanoporous electrospun poly(ε-caprolactone) fibres

Katsogiannis, Konstantinos A. G. January 2016 (has links)
Nanoporous polymer fibres are currently attracting increasing interest due to their unique characteristics. Increased specific surface area, improved mechanical properties and improved cellular growth are amongst the advantages that set porous fibres as ideal candidates in applications like catalysis, separation and tissue engineering. This work explores the single step production of porous poly(ε-caprolactone) (PCL) fibres through combinative electrospinning and Non-solvent Induced Phase Separation (NIPS) technique. Theoretical models, based on three different contact models (Hertzian, DMT, JKR), correlating the fibrous network specific surface area to material properties (density, surface tension, Young s modulus, Poisson s ratio) and network physical properties (density) and geometrical characteristics (fibre radius, fibre aspect ratio, network thickness) were developed in order to calculate the surface area increase caused by pore induction. Experimental results proved that a specific surface area increase of up to 56% could be achieved, compared to networks composed of smooth surfaced fibres. The good solvent effect on electrospun fibre surface morphology and size was examined through experimental investigation of four different good solvent (chloroform, dichloromethane, tetrahydrofuran and formic acid) based solutions at various good/poor solvent ratios. Chloroform was proven to be the most suitable solvent for good /poor solvent ratios varying from 75-90% v/v, whereas alternative mechanisms leading to different fibre morphologies were identified, interpreted and discussed. Evaporation rate of the good solvent was identified as the key parameter of the process. Second order polynomial equations, derived from the experimental data, correlating the feed solution physical parameters (viscosity, conductivity, surface tension) to the fibre average diameter produced were developed and validated. Response surface methodology was implemented for the design and conduction of electrospinning experiments on a 12.5 % w/v Chloroform/DMSO solution 90/10 % v/v in order to determine the individual process parameters (spinning distance, applied voltage, solution flow rate) effect in fibre surface morphology and size. The increase in any of these parameters results in increase of both the fibre size and the tendency for pore generation, whereas applied voltage was the parameter with the strongest effect. Findings from this thesis expand the knowledge about both phenomena occurring during the production process and end product properties, and can be used for the production of controlled morphology and size porous poly(ε-caprolactone) (PCL) fibres.
1052

Determinacao de elementos terras raras em rochas por analise por ativacao com neutrons com separacao pre-irradiacao

ALCALA, ANTONIO L. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:36:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:09Z (GMT). No. of bitstreams: 1 04223.pdf: 1419857 bytes, checksum: c459646dde6311c48fc0d2d70d417684 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
1053

Comportamento de extracao de especies complexas metal-azoteto com tri-n-octilamina-benzeno .Aplicacao a determinacao de impurezas em torio puro

BUENO, LUIZ A.O. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:25:55Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:28Z (GMT). No. of bitstreams: 1 11274.pdf: 2409354 bytes, checksum: d6b5c35f48ae749c8a0173449e8d1de1 (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
1054

Determinacao de microconstituintes em compostos de uranio por espectrometria de emissao atomica com fonte de plasma induzido (ICP-AES)

FURUSAWA, HELIO A. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:37:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:31Z (GMT). No. of bitstreams: 1 02046.pdf: 4605414 bytes, checksum: 083bd884df538642741b4cf2176f8795 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
1055

Tecnologia de purificacao de concentrados de torio e sua transformacao em produtos de pureza nuclear. Estudo do sitema TH(NOsub (3)) sub(4) -HNOsub(3)-TBP-varsol)

IKUTA, ALVARO 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:24:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:22Z (GMT). No. of bitstreams: 1 00020.pdf: 1979654 bytes, checksum: 18bc314b5b9ffe69f9ca23c2ea9dd3b2 (MD5) / Dissertacao (Mestrado) / IEA/D / Escola Politecnica, Universidade de Sao Paulo - POLI/USP
1056

Troca ionica focalizada - Aplicacao a separacao de elementos das terras raras

PUSCHEL, CLAUDIO R. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:24:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:22Z (GMT). No. of bitstreams: 1 00429.pdf: 872636 bytes, checksum: 9c83770eba88d0400824d10f4e45ebcb (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Química - Universidade de São Paulo - IQ/USP
1057

Contribuicao ao estudo da separacao zirconio/hafnio no sistema MIBK-HSCN-HCL

ZARPELON, LIA M.C. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:38:32Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:40Z (GMT). No. of bitstreams: 1 06010.pdf: 10090735 bytes, checksum: 27ba3c575e2c6be05736a4e1e736812a (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
1058

Estudo da determinacao de fosforo em amostras biologicas

OLIVEIRA, ROSANGELA M. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:38:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:09Z (GMT). No. of bitstreams: 1 05659.pdf: 3317573 bytes, checksum: 088eec0d018f1cd0f1976bad121d8428 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
1059

Viabilizacao do reaproveitamento dos blister de PVC/Al e estudos das propriedades do PVC apos processamento por radiacao ionizante / The viability of PVC/Al blister reuse and PVC property studies after ionizing radiation processing

CASTRO, ALEX T.P. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:55:13Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:01Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
1060

Separacao e concentracao de uranio por cromatografia de extracao .Sistema U(VI)- Hsub(3)POsub(4)

NOBRE, JULIA S.M. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:30:23Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:12Z (GMT). No. of bitstreams: 1 01263.pdf: 1423825 bytes, checksum: 763258d39fca71010a502429c52dd595 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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