The Experts below are selected from a list of 336 Experts worldwide ranked by ideXlab platform

Dimos Poulikakos - One of the best experts on this subject based on the ideXlab platform.

  • fabrication of multilayer passive and active electric components on polymer using inkjet printing and low temperature laser processing
    Sensors and Actuators A-physical, 2007
    Co-Authors: Jaewon Chung, Costas P Grigoropoulos, Heng Pan, Dimos Poulikakos
    Abstract:

    The low temperature fabrication of passive (conductor, capacitor) and active (field effect transistor) electrical components on flexible polymer substrate is presented in this paper. A drop-on-demand (DOD) ink-jetting system was used to print gold nano-particles suspended in Alpha-Terpineol solvent, PVP (poly-4-vinylphenol) in PGMEA (propylene glycol monomethyl ether acetate) solvent, semiconductor polymer (modified polythiophene) in chloroform solution to fabricate passive and active electrical components on flexible polymer substrates. Short pulsed laser ablation enabled finer electrical components to overcome the resolution limitation of inkjet deposition. Continuous argon ion laser was irradiated locally to evaporate the carrier solvent as well as sinter gold nano-particles. In addition, selective ablation of multilayered gold nanoparticle film was demonstrated using the novel SPLA-DAT (selective pulsed laser ablation by different ablation threshold) scheme for sintered and non-sintered gold nanoparticles. Finally, selective ablation of multilayered film was used to define narrow FET (field effect transistor) channel. Semiconductor polymer solution was deposited on top of channel to complete OFET (organic field effect transistor) fabrication.

  • air stable high resolution ofet organic field effect transistor fabrication using inkjet printing and low temperature selective laser sintering process
    Electronic and Photonic Packaging Electrical Systems Design and Photonics and Nanotechnology, 2006
    Co-Authors: Heng Pan, Costas P Grigoropoulos, Dimos Poulikakos
    Abstract:

    A novel high resolution OFET (organic field effect transistor) fabrication process has been developed to realize low cost, large area electronics at low processing temperature without use of expensive, high temperature lithography process in vacuum. A drop-on-demand (DOD) ink-jetting system was used to print gold nano-particles suspended in Alpha-Terpineol solvent. Continuous Argon ion laser was irradiated locally to evaporate carrier solvent as well as sinter gold nano-particles in order to fabricate metal source and drain electrodes with high resolution and minimal thermal damage to the substrate. PVP (poly-4-vinylphenol) in Hexanol solvent and air-stable semiconductor polymer (Carboxulate - functionalized Polythiophenes) in 1,2-dichlorobenzene (o-DCB) solvent were spin-coated to form thin film of dielectric layer and semiconducting active layer. All of the processes were carried out in plastic-compatible low temperature, ambient air and atmospheric pressure environment. The OFETs showed good accumulation mode p-channel transistor behavior with carrier mobility of 0.01cm2 /V·s and Ion /Ioff ratio of ranging from 103 to 104 .Copyright © 2006 by ASME

  • Subtractive Laser Processing of Low Temperature Inkjet Printed Micro Electric Components of Functional Nano-Ink for Flexible Electronics
    Advances in Electronic Packaging Parts A B and C, 2005
    Co-Authors: Seung Hwan Ko, Yeonho Choi, David J. Hwang, Jaewon Chung, Costas P Grigoropoulos, Dimos Poulikakos
    Abstract:

    The low temperature fabrication of electrical components on flexible substrate is presented in this paper. As an additive process, combined with a CAD tool, a drop-on-demand (DOD) inkjetting system was used to print electrical components from gold nano-particles suspended in Alpha-Terpineol solution on flexible polymer substrates. In a subtractive process, Nd:YAG pulsed laser was irradiated to produce finer electrical components. Continuous Ar laser was irradiated locally to evaporate carrier solution as well as to sinter gold nanoparticles. It is demonstrated for the first time, that the melting temperature depression of gold nanoink, combined with local laser heating and ablation can be used to fabricate micro electric components on low melting temperature polymer substrate to realize flexible electronics.Copyright © 2005 by ASME

  • fabrication of inkjet printed flexible electronics by low temperature subtractive laser processing
    Electronic and Photonic Packaging Electrical Systems Design and Photonics and Nanotechnology, 2005
    Co-Authors: Jaewon Chung, Yeonho Choi, Costas P Griogoropoulos, Dimos Poulikakos
    Abstract:

    The low temperature fabrication of passive electrical components (resistor, capacitor) on flexible substrates is presented in this paper. A drop-on-demand (DOD) ink-jetting system was used to print passive electrical components from gold nano-particles suspended in Alpha-Terpineol solution on a flexible polymer substrate. PVP (poly-4-vinylphenol) in PGMEA (propylene glycol monomethyl ether acetate) solvent was inkjet-printed as dielectric layer for capacitor. A pulsed laser beam was irradiated to produce finer electrical components, thereby overcoming the inherent limitation of inkjet processing. A continuous Ar laser beam was irradiated locally to evaporate carrier solvent as well as to cure the gold nano-particles in order to improve the electrical resistivity. Conductor lines and capacitors were fabricated on polymer substrate and their performance was analyzed.Copyright © 2005 by ASME

André Camargo De ,azevedo - One of the best experts on this subject based on the ideXlab platform.

  • Estudos de geração e caracterização físico-química de nanobolhas produzidas por despressurização e aplicações em sistemas de flotação
    2017
    Co-Authors: André Camargo De ,azevedo
    Abstract:

    O presente trabalho descreve um estudo teórico-experimental da geração de nanobolhas (NBs) por despressurização, da caracterização físico-química das dispersões aquosas de NBs e seus efeitos nos sistemas de flotação de minérios e efluentes líquidos, nas etapas de agregação, condicionamento e flotação. A geração de NBs foi realizada em um sistema de bancada de Flotação por Ar Dissolvido (FAD), por despressurização de uma corrente aquosa supersaturada em ar em um constritor de fluxo (válvula agulha), onde ocorre o fenômeno de cavitação hidrodinâmica com geração de microbolhas (MBs) e NBs. Após, um procedimento de separação das NBs em uma coluna de vidro foi realizado, explorando o fato de que as MBs ascendem e colapsam na superfície do líquido, enquanto as NBs são estáveis e permanecem em suspensão por longos períodos de tempo. As dispersões aquosas de NBs foram caracterizadas medindo diversos parâmetros físicos e físico-químicos, entre outros: concentração numérica, diâmetro médio-Dm, potencial zeta-PZ e tempo de vida. Para tanto, foram usadas as técnicas de Nanoparticle Tracking Analysis (NTA, ZetaView®, Particle Matrix, Germany) e Dynamic Light Scattering (DLS, NanoZetaSizer®, Malvern, UK). Ainda, foram avaliadas diferentes condições de geração para os parâmetros pressão de saturação e tensão superficial da solução aquosa Os resultados demonstraram que a concentração de NBs é inversamente proporcional a pressão de saturação e a tensão superficial do líquido, atingindo o valor de 1,6 x 109 NBs.mL-1 com Psat = 2,5 bar e solução de alfa-Terpineol (100 mg.L-1 e Tsup = 49 mN.m-1). Ainda, medidas de NTA demonstraram que as NBs permanecem estáveis, sem mudanças significativas na sua concentração numérica e no tamanho médio, por um período superior a 14 dias. Ainda, com o preparo de amostra da dispersão aquosa de NBs com uso de corante azul de metileno, foi possível a realização de microfotografias de dispersões aquosas de NBs, uma vez que o corante adsorve na superfície das bolhas e possibilita um contraste visual necessário para obtenção de imagens por microscopia ótica. As interações de NBs com partículas minerais, precipitados coloidais de aminas e microbolhas foram estudadas, assim como seus efeitos na flotação aplicada a esses sistemas (partículas de quartzo e precipitados de aminas). Os resultados de flotação mostraram que as nanobolhas isoladas não são capazes de flotar as partículas de quartzo, devido ao baixo lifting power das NBs. Entretanto, quando utilizadas em uma etapa de condicionamento do quartzo, antes da flotação com macrobolhas, foram responsáveis por aumentar significativamente a flotação de partículas finas ( 212 μm). Os precipitados de amina foram formados em meio alcalino (insolubilização) a partir de concentração 10-3 mol.L-1, pH >10,5 e após 30 min de agitação. As medidas de tamanho e potencial zeta, em função do pH do meio, mostraram que os colóides formados apresentaram tamanhos na ordem de nanômetros (120 – 350 nm), sendo que o máximo crescimento foi obtido próximo ao ponto isoelétrico (pH 11). Os estudos de flotação dos precipitados coloidais de amina revelaram que as nanobolhas isoladas foram altamente eficientes, atingindo valores de remoção em torno de 80%. Por sua vez, a flotação com microbolhas juntamente com as nanobolhas apresentaram valores de remoção de amina entre 50 – 60 %. Para validar os resultados obtidos previamente dos efeitos das NBs na flotação de quartzo e precipitados coloidais de aminas, foram realizados estudos com condicionamento de partículas finas de quartzo (D32 = 8 μm) e de precipitados de aminas com NBs e análise por microscopia ótica (magnificação de 1000x), demonstrando visualmente a agregação desses sistemas particulados. Acredita-se que a presente Tese de doutorado traz avanços na geração de NBs dispersas em alta concentração e apresenta dados inéditos de caracterização física e físico-química desses sistemas, contribuindo para um melhor entendimento dos efeitos das NBs em diferentes sistemas de flotação no tratamento de minérios e de efluentes líquidos e possibilitando o desenvolvimento de novas técnicas que utilizam NBs em diferentes áreas da engenharia e outras ciências aplicadas.The present work describes a theoretical and experimental study of the generation of nanobubbles (NBs) by depressurization, the physico-chemical characterization of aqueous dispersions of NBs and its effects on flotation systems of minerals and liquid effluents, in the steps of aggregation, conditioning and flotation. The generation of NBs was performed in a bench system of Dissolved Air Flotation (DAF) for depressurizing an aqueous stream supersaturated in air at a flow constrictor (needle valve), where the hydrodynamic cavitation phenomenon generating microbubbles (MBs) and NBs occurs. After, a separation procedure of NBs in a glass column was accomplished by exploiting the fact that the MBs rise and collapse on the liquid surface, while the NBs are stable and remain suspended in the liquid for long periods of time. The aqueous dispersions of NBs were characterized by measuring physical and physicochemical parameters, among others: numerical concentration, mean diameter-Dm, zeta potential-PZ and lifetime. For that, it was used the techniques of Nanoparticle Tracking Analysis (NTA, ZetaView®, Particle Matrix, Germany) and Dynamic Light Scattering (DLS, NanoZetaSizer®, Malvern, UK) Different conditions for the generation of NBs were evaluated for the parameters of saturation pressure and surface tension of the aqueous solution. The results showed that the concentration of NBs is inversely proportional to the saturation pressure and the surface tension of the liquid, reaching the value of 1.6 x 109 NBs mL-1 with Psat = 2.5 bar and Alpha-Terpineol solution ( 100 mg L-1 and surface tension = 49 mN m-1). Yet, measurements by NTA technique showed that NBs are stable without significant changes in their number concentration and their mean size, for a period of at least 14 days. Furthermore, with the use of methylene blue dye in the preparation of the sample of aqueous dispersion of NBs, it was possible to perform photomicrographs of aqueous dispersions of NBs, since the colorant adsorbs on the surface of the bubbles and provides a visual contrast needed to obtain pictures by optical microscopy. The NBs interactions with mineral particles (quartz), colloidal amines precipitates and microbubbles were studied, as well as its effects on flotation applied to these systems (quartz particles and amines precipitates) The results showed that flotation with isolated nanobubbles are not able to float quartz particles due to the low lifting power of NBs. However, when used in a conditioning step of the quartz particles prior to the flotation with macrobubbles, the NBs were responsible for significantly increasing the flotation of fine quartz particles ( 212 μm) The amines precipitates were formed in alkaline medium (insolubilization) with a concentration of 10-3 mol L-1 and pH > 10.5, after 30 min of stirring. The size and zeta potential measurements as a function of pH, showed that the colloids formed had sizes in the nanometer range (120-350 nm), and maximum growth was obtained near the isoelectric point (pH 11). Flotation studies of amines colloidal precipitates revealed that the isolated nanobubbles were highly efficient, reaching values of amine removal near 80%. On the other hand, the flotation with microbubbles jointly with nanobubbles presented amines removal efficiency about 50 – 60 %. To validate previously obtained results of the effects of NBs in the flotation of quartz and amines colloidal precipitates, studies were performed with conditioning of fine quartz particles (D32 = 8 microns) and precipitated amines with NBs and analysis by optical-microscopy (magnification 1000x), visually demonstrating the aggregation of these particulate systems It is believed that this doctoral thesis provides advances in the generation of dispersed NBs at high concentration and provides novel data of physical and physicochemical characterization of such systems and contributes to a better understanding of the effects of NBs in different flotation systems in the beneficiation of minerals and the treatment of liquid effluents and enabling the development of new techniques that use NBs in different areas of engineering and other applied sciences

  • Estudos de geração e caracterização físico-química de nanobolhas produzidas por despressurização e aplicações em sistemas de flotação
    Universidade Federal do Rio Grande do Sul, 2017
    Co-Authors: André Camargo De ,azevedo
    Abstract:

    O presente trabalho descreve um estudo teórico-experimental da geração de nanobolhas (NBs) por despressurização, da caracterização físico-química das dispersões aquosas de NBs e seus efeitos nos sistemas de flotação de minérios e efluentes líquidos, nas etapas de agregação, condicionamento e flotação. A geração de NBs foi realizada em um sistema de bancada de Flotação por Ar Dissolvido (FAD), por despressurização de uma corrente aquosa supersaturada em ar em um constritor de fluxo (válvula agulha), onde ocorre o fenômeno de cavitação hidrodinâmica com geração de microbolhas (MBs) e NBs. Após, um procedimento de separação das NBs em uma coluna de vidro foi realizado, explorando o fato de que as MBs ascendem e colapsam na superfície do líquido, enquanto as NBs são estáveis e permanecem em suspensão por longos períodos de tempo. As dispersões aquosas de NBs foram caracterizadas medindo diversos parâmetros físicos e físico-químicos, entre outros: concentração numérica, diâmetro médio-Dm, potencial zeta-PZ e tempo de vida. Para tanto, foram usadas as técnicas de Nanoparticle Tracking Analysis (NTA, ZetaView®, Particle Matrix, Germany) e Dynamic Light Scattering (DLS, NanoZetaSizer®, Malvern, UK). Ainda, foram avaliadas diferentes condições de geração para os parâmetros pressão de saturação e tensão superficial da solução aquosa Os resultados demonstraram que a concentração de NBs é inversamente proporcional a pressão de saturação e a tensão superficial do líquido, atingindo o valor de 1,6 x 109 NBs.mL-1 com Psat = 2,5 bar e solução de alfa-Terpineol (100 mg.L-1 e Tsup = 49 mN.m-1). Ainda, medidas de NTA demonstraram que as NBs permanecem estáveis, sem mudanças significativas na sua concentração numérica e no tamanho médio, por um período superior a 14 dias. Ainda, com o preparo de amostra da dispersão aquosa de NBs com uso de corante azul de metileno, foi possível a realização de microfotografias de dispersões aquosas de NBs, uma vez que o corante adsorve na superfície das bolhas e possibilita um contraste visual necessário para obtenção de imagens por microscopia ótica. As interações de NBs com partículas minerais, precipitados coloidais de aminas e microbolhas foram estudadas, assim como seus efeitos na flotação aplicada a esses sistemas (partículas de quartzo e precipitados de aminas). Os resultados de flotação mostraram que as nanobolhas isoladas não são capazes de flotar as partículas de quartzo, devido ao baixo lifting power das NBs. Entretanto, quando utilizadas em uma etapa de condicionamento do quartzo, antes da flotação com macrobolhas, foram responsáveis por aumentar significativamente a flotação de partículas finas ( 212 μm). Os precipitados de amina foram formados em meio alcalino (insolubilização) a partir de concentração 10-3 mol.L-1, pH >10,5 e após 30 min de agitação. As medidas de tamanho e potencial zeta, em função do pH do meio, mostraram que os colóides formados apresentaram tamanhos na ordem de nanômetros (120 – 350 nm), sendo que o máximo crescimento foi obtido próximo ao ponto isoelétrico (pH 11). Os estudos de flotação dos precipitados coloidais de amina revelaram que as nanobolhas isoladas foram altamente eficientes, atingindo valores de remoção em torno de 80%. Por sua vez, a flotação com microbolhas juntamente com as nanobolhas apresentaram valores de remoção de amina entre 50 – 60 %. Para validar os resultados obtidos previamente dos efeitos das NBs na flotação de quartzo e precipitados coloidais de aminas, foram realizados estudos com condicionamento de partículas finas de quartzo (D32 = 8 μm) e de precipitados de aminas com NBs e análise por microscopia ótica (magnificação de 1000x), demonstrando visualmente a agregação desses sistemas particulados. Acredita-se que a presente Tese de doutorado traz avanços na geração de NBs dispersas em alta concentração e apresenta dados inéditos de caracterização física e físico-química desses sistemas, contribuindo para um melhor entendimento dos efeitos das NBs em diferentes sistemas de flotação no tratamento de minérios e de efluentes líquidos e possibilitando o desenvolvimento de novas técnicas que utilizam NBs em diferentes áreas da engenharia e outras ciências aplicadas.The present work describes a theoretical and experimental study of the generation of nanobubbles (NBs) by depressurization, the physico-chemical characterization of aqueous dispersions of NBs and its effects on flotation systems of minerals and liquid effluents, in the steps of aggregation, conditioning and flotation. The generation of NBs was performed in a bench system of Dissolved Air Flotation (DAF) for depressurizing an aqueous stream supersaturated in air at a flow constrictor (needle valve), where the hydrodynamic cavitation phenomenon generating microbubbles (MBs) and NBs occurs. After, a separation procedure of NBs in a glass column was accomplished by exploiting the fact that the MBs rise and collapse on the liquid surface, while the NBs are stable and remain suspended in the liquid for long periods of time. The aqueous dispersions of NBs were characterized by measuring physical and physicochemical parameters, among others: numerical concentration, mean diameter-Dm, zeta potential-PZ and lifetime. For that, it was used the techniques of Nanoparticle Tracking Analysis (NTA, ZetaView®, Particle Matrix, Germany) and Dynamic Light Scattering (DLS, NanoZetaSizer®, Malvern, UK) Different conditions for the generation of NBs were evaluated for the parameters of saturation pressure and surface tension of the aqueous solution. The results showed that the concentration of NBs is inversely proportional to the saturation pressure and the surface tension of the liquid, reaching the value of 1.6 x 109 NBs mL-1 with Psat = 2.5 bar and Alpha-Terpineol solution ( 100 mg L-1 and surface tension = 49 mN m-1). Yet, measurements by NTA technique showed that NBs are stable without significant changes in their number concentration and their mean size, for a period of at least 14 days. Furthermore, with the use of methylene blue dye in the preparation of the sample of aqueous dispersion of NBs, it was possible to perform photomicrographs of aqueous dispersions of NBs, since the colorant adsorbs on the surface of the bubbles and provides a visual contrast needed to obtain pictures by optical microscopy. The NBs interactions with mineral particles (quartz), colloidal amines precipitates and microbubbles were studied, as well as its effects on flotation applied to these systems (quartz particles and amines precipitates) The results showed that flotation with isolated nanobubbles are not able to float quartz particles due to the low lifting power of NBs. However, when used in a conditioning step of the quartz particles prior to the flotation with macrobubbles, the NBs were responsible for significantly increasing the flotation of fine quartz particles (< 37 mm) by about 20%. However, the same effect was not observed in the recovery of coarse particles (> 212 μm) The amines precipitates were formed in alkaline medium (insolubilization) with a concentration of 10-3 mol L-1 and pH > 10.5, after 30 min of stirring. The size and zeta potential measurements as a function of pH, showed that the colloids formed had sizes in the nanometer range (120-350 nm), and maximum growth was obtained near the isoelectric point (pH 11). Flotation studies of amines colloidal precipitates revealed that the isolated nanobubbles were highly efficient, reaching values of amine removal near 80%. On the other hand, the flotation with microbubbles jointly with nanobubbles presented amines removal efficiency about 50 – 60 %. To validate previously obtained results of the effects of NBs in the flotation of quartz and amines colloidal precipitates, studies were performed with conditioning of fine quartz particles (D32 = 8 microns) and precipitated amines with NBs and analysis by optical-microscopy (magnification 1000x), visually demonstrating the aggregation of these particulate systems It is believed that this doctoral thesis provides advances in the generation of dispersed NBs at high concentration and provides novel data of physical and physicochemical characterization of such systems and contributes to a better understanding of the effects of NBs in different flotation systems in the beneficiation of minerals and the treatment of liquid effluents and enabling the development of new techniques that use NBs in different areas of engineering and other applied sciences

Magali Monteiro - One of the best experts on this subject based on the ideXlab platform.

  • changes in the aroma of organic passion fruit passiflora edulis sims f flavicarpa deg during ripeness
    Lwt - Food Science and Technology, 2014
    Co-Authors: Natalia Soares Janzantti, Magali Monteiro
    Abstract:

    Abstract The odoriferous importance of volatile compounds during maturation of organic passion fruit was studied. The volatile compounds were analyzed using GC-FID-OSME and GC-MS. The volatile profile changed throughout maturation. Relative peak area improved from the 1/3 to 2/3 yellow skin color state of ripeness and was still improved from the 2/3 to 3/3, but the profile remained. Ethyl butanoate showed the highest relative peak area and importance for the aroma of the organic passion fruit in the 1/3 yellow skin color. Ethyl butanoate and hexanoate, propyl acetate and Alpha-Terpineol showed odoriferous importance from the 2/3 yellow skin color, and together with diethyl carbonate and cis-3-hexen-1-ol were the most important compounds in the 3/3 yellow skin color state of ripeness. PCA allowed clearly differentiate all ripening states, indicating that hexanal and caramel, earthy and synthetic aroma were most closely associated with the unripe passion fruit. 2-methylpropyl acetate characterized the passion fruit at the 2/3 yellow skin color together with cis-beta-ocimene, benzaldehyde and aroma sweet and passion fruit, skin, which also were associated with the 3/3 yellow skin color. Esters, terpenes, alcohols, octanal, dodecanol and aroma of passion fruit, fruity, citric, candy and plastic were closely associated with the whole maturation.

  • influence of the cultivation system in the aroma of the volatile compounds and total antioxidant activity of passion fruit
    Lwt - Food Science and Technology, 2012
    Co-Authors: Natalia Soares Janzantti, Mariana Serrao Macoris, Deborah Dos Santos Garruti, Magali Monteiro
    Abstract:

    The aim of this study was to investigate the influence of the cultivation system on the volatile composition of the passion fruit and to determine the odoriferous contribution of the compounds for the aroma of the organic and conventional fruit, besides to assess the total antioxidant activity. The volatile compounds were isolated from dynamic headspace, separated by high-resolution gas chromatography and the odoriferous contribution to the passion fruit aroma was evaluated using the OSME technique. Total antioxidant activity was determined using the ABTS radical reaction. The organic and conventional passion fruit showed similar volatile profile, although some differences occurred. Ethyl 2-propenoate, 2-methyl-1-propanol, diethyl carbonate and ethyl hexanoate were threefold higher in the organic fruit while butyl acetate, hexanal, cis-3-hexenyl acetate and trans-3-hexenyl butanoate were threefold higher in the conventional fruit. Hexanoate and acetate esters, and saturated alcohols described as fruity, sweet, citrus and passion-fruit aroma showed the highest odorific intensity in the organic fruit. Furthermore, trans and cis-3-hexenyl acetate and alpha-copaene, Alpha-Terpineol, D-limonene, trans-beta-ocimene and delta-cadinene had higher contribution to the organic passion fruit aroma. On the other hand, unsaturated alcohols, beta-myrcene and beta-linalool described as grass, sulfur-like and passion-fruit aroma were higher in the conventional fruit. The organic passion fruit showed higher levels of total phenolic compounds and total antioxidant activity than the conventional fruit, suggesting that the cultivation system influenced the production of antioxidant bioactive compounds.

Jaewon Chung - One of the best experts on this subject based on the ideXlab platform.

  • fabrication of multilayer passive and active electric components on polymer using inkjet printing and low temperature laser processing
    Sensors and Actuators A-physical, 2007
    Co-Authors: Jaewon Chung, Costas P Grigoropoulos, Heng Pan, Dimos Poulikakos
    Abstract:

    The low temperature fabrication of passive (conductor, capacitor) and active (field effect transistor) electrical components on flexible polymer substrate is presented in this paper. A drop-on-demand (DOD) ink-jetting system was used to print gold nano-particles suspended in Alpha-Terpineol solvent, PVP (poly-4-vinylphenol) in PGMEA (propylene glycol monomethyl ether acetate) solvent, semiconductor polymer (modified polythiophene) in chloroform solution to fabricate passive and active electrical components on flexible polymer substrates. Short pulsed laser ablation enabled finer electrical components to overcome the resolution limitation of inkjet deposition. Continuous argon ion laser was irradiated locally to evaporate the carrier solvent as well as sinter gold nano-particles. In addition, selective ablation of multilayered gold nanoparticle film was demonstrated using the novel SPLA-DAT (selective pulsed laser ablation by different ablation threshold) scheme for sintered and non-sintered gold nanoparticles. Finally, selective ablation of multilayered film was used to define narrow FET (field effect transistor) channel. Semiconductor polymer solution was deposited on top of channel to complete OFET (organic field effect transistor) fabrication.

  • Subtractive Laser Processing of Low Temperature Inkjet Printed Micro Electric Components of Functional Nano-Ink for Flexible Electronics
    Advances in Electronic Packaging Parts A B and C, 2005
    Co-Authors: Seung Hwan Ko, Yeonho Choi, David J. Hwang, Jaewon Chung, Costas P Grigoropoulos, Dimos Poulikakos
    Abstract:

    The low temperature fabrication of electrical components on flexible substrate is presented in this paper. As an additive process, combined with a CAD tool, a drop-on-demand (DOD) inkjetting system was used to print electrical components from gold nano-particles suspended in Alpha-Terpineol solution on flexible polymer substrates. In a subtractive process, Nd:YAG pulsed laser was irradiated to produce finer electrical components. Continuous Ar laser was irradiated locally to evaporate carrier solution as well as to sinter gold nanoparticles. It is demonstrated for the first time, that the melting temperature depression of gold nanoink, combined with local laser heating and ablation can be used to fabricate micro electric components on low melting temperature polymer substrate to realize flexible electronics.Copyright © 2005 by ASME

  • fabrication of inkjet printed flexible electronics by low temperature subtractive laser processing
    Electronic and Photonic Packaging Electrical Systems Design and Photonics and Nanotechnology, 2005
    Co-Authors: Jaewon Chung, Yeonho Choi, Costas P Griogoropoulos, Dimos Poulikakos
    Abstract:

    The low temperature fabrication of passive electrical components (resistor, capacitor) on flexible substrates is presented in this paper. A drop-on-demand (DOD) ink-jetting system was used to print passive electrical components from gold nano-particles suspended in Alpha-Terpineol solution on a flexible polymer substrate. PVP (poly-4-vinylphenol) in PGMEA (propylene glycol monomethyl ether acetate) solvent was inkjet-printed as dielectric layer for capacitor. A pulsed laser beam was irradiated to produce finer electrical components, thereby overcoming the inherent limitation of inkjet processing. A continuous Ar laser beam was irradiated locally to evaporate carrier solvent as well as to cure the gold nano-particles in order to improve the electrical resistivity. Conductor lines and capacitors were fabricated on polymer substrate and their performance was analyzed.Copyright © 2005 by ASME

Youngjoon Ahn - One of the best experts on this subject based on the ideXlab platform.

  • fumigant toxicity of summer savory and lemon balm oil constituents and efficacy of spray formulations containing the oils to b and neonicotinoid resistant q biotypes of bemisia tabaci homoptera aleyrodidae
    Journal of Economic Entomology, 2014
    Co-Authors: Songhwa Chae, Soonil Kim, Seong Hum Yeon, Haribalan Perumalsamy, Youngjoon Ahn
    Abstract:

    An assessment was made of the fumigant toxicity of 36 constituents from lemon balm oil (LBO) and summer savory oil (SSO) and another additional nine previously identified compounds of the oils, as well as of the control efficacy of four experimental spray formulations containing individual oils (0.5 and 0.1% sprays) and spinosad 10% suspension concentrate (SC) to females from B- and neonicotinoid-resistant Q-biotypes of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Based on 24-h LC50 values, Q-biotype females (0.20 microg/cm3) were 40 times less susceptible to dichlorvos than B-biotype females (0.005 microg/cm3). Thymol (LC50, 0.35 microg/cm3) and carvacrol (0.56 microg/cm3) were the most toxic compounds toward Q-biotype females, followed by (1S)-(-)-borneol, Alpha-Terpineol, nerol, linalool, and carvone (1.06-1.38 microg/cm3). The toxicity of these compounds was virtually identical toward both biotype females, indicating that the terpenoids and the insecticides (neonicotinoids and dichlorvos) do not share a common mode of action or elicit cross-resistance. The 0.5% spray of LBO, SSO, and spinosad 10% SC resulted in >90% mortality toward both biotype females. Global efforts to reduce the level of toxic synthetic insecticides in the agricultural environment justify further studies on LBO- and SSO-derived materials as potential contact-action fumigants for the control of B. tabaci populations.

  • ovicidal and adulticidal activities of origanum majorana essential oil constituents against insecticide susceptible and pyrethroid malathion resistant pediculus humanus capitis anoplura pediculidae
    Journal of Agricultural and Food Chemistry, 2009
    Co-Authors: Youngcheol Yang, Marshall J Clark, Si Hyeock Lee, Youngjoon Ahn
    Abstract:

    The toxicity of essential oil constituents from marjoram, Origanum majorana, to eggs and adult females of the susceptible KR-HL and dual malathion- and permethrin-resistant BR-HL strains of human head louse, Pediculus humanus capitis, was examined using contact + fumigant mortality bioassay. Results were compared with those following treatment with two pyrethroid pediculicides, d-phenothrin or pyrethrum. As judged by the lethal time to 50% mortality (LT(50)) values at the exposure rate of 0.25 mg/cm(2), 1,8-cineole (14.1 min) was the most toxic compound, followed by linalool (15.4 min) to KR-HL females. These compounds were faster acting than either d-phenothrin (24.1 min) or pyrethrum (33.4 min). Based on the lethal concentration causing 50% mortality (LC(50)) values, (-)-camphor (0.022 mg/cm(2)) was the most toxic compound, followed by linalool (0.035 mg/cm(2)), (-)-terpinen-4-ol (0.040 mg/cm(2)), Alpha-Terpineol (0.045 mg/cm(2)), and 1,8-cineole (0.068 mg/cm(2)) against KR-HL females. These monoterpenoids were less toxic than either d-phenothrin (LC(50), 0.0015 mg/cm(2)) or pyrethrum (0.0013 mg/cm(2)). However, the toxicities of these monoterpenoids were almost identical against females from either of the two strains, even though the BR-HL females exhibited high levels of resistance to d-phenothrin [resistance ratio (RR), 667] and pyrethrum (RR, 754). After a 24 h exposure to linalool, BR-HL egg hatch was inhibited 100 and 84% at 0.25 or 0.125 mg/cm(2), respectively, while (-)-terpinen-4-ol caused 94 and 69% inhibition of egg hatch at 0.25 and 0.125 mg/cm(2). Alpha-Terpineol caused 88 and 76% inhibition of egg hatch at 0.5 and 0.25 mg/cm(2), respectively. Thus, certain monoterpenoids from O. majorana essential oil, particularly linalool, (-)-terpinen-4-ol and Alpha-Terpineol, merit further study as potential pediculicides and ovicides for the control of insecticide-resistant P. h. capitis populations as fumigants with contact action.

  • toxicity of myristica fragrans seed compounds against blattella germanica dictyoptera blattellidae
    Journal of Medical Entomology, 2007
    Co-Authors: Woochul Jung, Youngsu Jang, Tran Trung Hieu, Chongkyu Lee, Youngjoon Ahn
    Abstract:

    The insecticidal constituents of hexane-soluble fraction from a methanolic extract of the seeds from Myristica fragrans (Myristicaceae) against adult females of Blattella germanica (L.) (Dictyoptera: Blattellidae) were analyzed by gas chromatography and gas chromatography-mass spectrometry. The insecticidal activity of 13 Myristica seed compounds against female B. germanica was examined by using the filter-paper contact toxicity and vapor phase toxicity bioassays. Results were compared with those of the other 23 known compounds of Myristica seed and currently used insecticides: dichlorvos, deltamethrin, permethrin, and propoxur. In contact toxicity tests using female B. germanica, (IS)-(-) -beta-pinene (0.06 mg/cm2) was the most toxic insecticide, based on 24-h LD50 values. The insecticidal activity of this compound was comparable with that of permethrin (0.05 mg/cm2). (1R)-(+) -Camphor, (1S)-(-) -camphor, dipentene, (1R)-(+) -3-pinene, and (+)-Alpha-Terpineol (0.10-0.14 mg/cm2) were more toxic than propoxur (0.19 mg/cm2). (E)-Sabinene hydrate and propoxur were almost equitoxic. Potent insecticidal activity also was observed with (R)-(+) -citronellal, (S)-(-) -citronellal, (R)-(-) -alpha-phellandrene, (1S)-(-) -alpha-pinene, (1R)-(+) -alpha-pinene, and safrole (0.27-0.48 mg/cm2). In vapor phase toxicity tests, the compounds tested were effective in closed but not in open containers. These results indicate that the effect of these compounds was largely a result of action in the vapor phase. Myristica seed compounds described merit further study as potential insecticides or as leads for the control of cockroaches.

  • vapor phase toxicity of marjoram oil compounds and their related monoterpenoids to blattella germanica orthoptera blattellidae
    Journal of Agricultural and Food Chemistry, 2005
    Co-Authors: Youngsu Jang, Youngcheol Yang, Dalsoon Choi, Youngjoon Ahn
    Abstract:

    The toxicity of marjoram, Origanum majorana L., oil, 41 monoterpenoids, and 2 sesquiterpenoids against adult females of the German cockroach, Blattella germanica L., was examined using direct contact and vapor phase toxicity bioassays and compared with those of deltamethrin, dichlorvos, permethrin, and propoxur, four commonly used insecticides. In a filter-paper contact toxicity bioassay, the adulticidal activities of pulegone (0.06 mg/cm2), (+/-)-camphor (0.07 mg/cm2), and verbenone (0.07 mg/cm2) were comparable to that of permethrin (0.05 mg/cm2) but more pronounced than that of propoxur (0.18 mg/cm2), as judged by the 24-h LC50 values. These compounds were less effective than either deltamethrin (0.013 mg/cm2) or dichlorvos (0.007 mg/cm2). The toxicity of marjoram oil, thymol, Alpha-Terpineol, (-)-alpha-thujone, linalool, 1,8-cineole, (-)-camphor, and (+)-carvone, ranging from 0.08 to 0.18 mg/cm2, was higher than that of propoxur. In vapor phase toxicity tests, verbenone (11.48 mg/L air) was the most toxic compound followed by (-)-alpha-thujone (18.43 mg/L of air), thymol (18.76 mg/L of air), Alpha-Terpineol (21.89 mg/L of air), (+/-)-camphor (24.59 mg/L of air), linalool (26.20 mg/L of air), and marjoram oil (38.28 mg/L of air) on the basis of the 24-h LC50 values. Dichlorvos (0.07 mg/L of air) was the most potent fumigant. Structure-activity relationships indicate that structural characteristics, such as degrees of saturation and types of functional groups rather than types of carbon skeleton, and hydrophobicity and vapor pressure parameters appear to play a role in determining the monoterpenoid toxicities to adult B. germanica. Marjoram oil and the monoterpenoids described merit further study as potential fumigants or leads for the control of B. germanica.