Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Membranes (Basel) ; 9(7)2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31319501

RESUMO

Hydrophobic pure-silica *BEA-type zeolite membranes with large pores were prepared on tubular silica supports by hydrothermal synthesis using a secondary growth method and were applied to the separation of alcohol/water mixtures by pervaporation (PV), an alternative energy-efficient process for production of biofuels. Amorphous pure-silica tubular silica supports, free of Al atoms, were used for preparing the membranes. In this study, the effects of the synthesis conditions, such as the H2O/SiO2 and NH4F/SiO2 ratios in the synthetic gel, on the membrane formation process and separation performance were systematically investigated. The successfully prepared dense and continuous membranes exhibited alcohol selectivity and high flux for the separation of ethanol/water and butanol/water mixtures. The pure-silica *BEA membranes obtained under optimal conditions (0.08SiO2:0.5TEAOH:0.7NH4F:8H2O) showed high PV performance with a separation factor of 229 and a flux of 0.62 kg·m-2·h-1 for a 1 wt % n-butanol/water mixture at 318 K. This result was attributed to the hydrophobicity and large pore size of the pure-silica *BEA membrane. This was the first successful synthesis of hydrophobic large-pore zeolite membranes on tubular supports with alcohol selectivity, and the obtained results could provide new insights into the research on hydrophobic membranes with high permeability.

2.
Membranes (Basel) ; 9(4)2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30939830

RESUMO

Silicalite-1 membranes with high pervaporation performance were prepared successfully on a silica-particle-coated tubular silica support using a gel-free steam-assisted conversion (SAC) method. The effects of the silica-particle layer formed on the top surface of the silica support and the physical properties of the silica particles themselves on the membrane-formation process were investigated. The silica particles coated served as the additional silica source for growing the silicalite-1 seed crystal layer into the silicalite-1 membrane. As a result, it was possible to form a dense and continuous membrane even under gel-free conditions. Furthermore, it was found that the properties of the silica particles, such as their primary particle diameter, had a determining effect on their solubility during the steam treatment, that is, on the supply rate of the silica source. The silicalite-1 membrane obtained using the spherical-silica-particle-coated support had an approximately 9-µm-thick separation layer and showed very high pervaporation performance, exhibiting a separation factor of 105 and a flux of 3.72 kg m-2 h-1 for a 10 wt % ethanol/water mixture at 323 K. Thus, the gel-free SAC method can be used with a silica support coated with silica particles to readily prepare high-performance membranes without producing any chemical waste.

3.
J Biosci Bioeng ; 121(6): 697-700, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26718336

RESUMO

We investigated butanol recovery by pervaporation separation, using a silicalite-1 membrane, from batch cultures of butanol-producing Clostridium beijerinckii SBP2 grown on sweet sorghum juice as a fermentation medium. The pervaporation system yielded 73% (w/v) butanol from intact feed cultures containing 1% (w/v) butanol, and had a butanol permeation flux of 11 g m(-2) h(-1). Upon neutralization and activated charcoal treatment of the feed cultures, butanol yield and total flux increased to 82% (w/v) and 40 g m(-2) h(-1), respectively. This system is applicable to refining processes for practical biobutanol production from a promising energy crop, sweet sorghum.


Assuntos
1-Butanol/isolamento & purificação , 1-Butanol/metabolismo , Acetona/metabolismo , Clostridium beijerinckii/metabolismo , Etanol/metabolismo , Fermentação , Membranas Artificiais , Sorghum/química , Técnicas de Cultura Celular por Lotes , Carvão Vegetal , Clostridium beijerinckii/crescimento & desenvolvimento , Volatilização
4.
Bioresour Technol ; 116: 448-52, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22575842

RESUMO

A polytetrafluoroethylene (PTFE) membrane was used in membrane-assisted extractive (MAE) fermentation of acetone-butanol-ethanol (ABE) by Clostridium saccharoperbutylacetonicum N1-4. The growth inhibition effects of 1-dodecanol, which has a high partition coefficient for butanol, can be prevented by employing 1-dodecanol as an extractant when using a PTFE membrane. Compared to conventional fermentation, MAE-ABE fermentation with 1-dodecanol decreased butanol inhibition and increased glucose consumption from 59.4 to 86.0 g/L, and total butanol production increased from 16.0 to 20.1g/L. The maximum butanol production rate increased from 0.817 to 0.979 g/L/h. The butanol productivity per membrane area was remarkably high with this system, i.e., 78.6g/L/h/m(2). Therefore, it is expected that this MAE fermentation system can achieve footprint downsizing.


Assuntos
1-Butanol/metabolismo , Clostridium/efeitos dos fármacos , Clostridium/metabolismo , Dodecanol/farmacologia , Fermentação/fisiologia , Extração Líquido-Líquido , Membranas Artificiais , Acetona/metabolismo , Técnicas de Cultura Celular por Lotes , Clostridium/crescimento & desenvolvimento , Dodecanol/toxicidade , Etanol/metabolismo , Politetrafluoretileno
5.
J Prosthodont Res ; 54(4): 185-91, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20472524

RESUMO

PURPOSE: This study was to develop a titanium dioxide (TiO(2))-coated implant abutment, surface with ultraviolet (UV) light-induced hydrophilicity and investigate the initial response of human, fibroblasts to the surface modification. MATERIALS AND METHODS: Commercially pure titanium (JIS 2 grade) disks were coated with TiO(2) to various, thicknesses (1, 2 or 3 µm) using peroxotitanium acid solution. The surface characteristics of each disk, were examined with X-ray diffraction (XRD), surface roughness equipment and scanning electron, microscopy (SEM). The hydrophilic change of each disk was determined by the contact angles at 0-24h, after 24-h UV irradiation. The biological response at the surface of each disk was examined by using, human periodontal ligament fibroblasts (HPLFs). The data were statistically analyzed with analysis of variance (ANOVA) and multiple-comparison tests. RESULTS: The TiO(2)-coated disk surface had an anatase structure. Surface roughness did not differ, significantly among the disks; the surface morphology was smooth and had a hydrophilic or superhydrophilic, status. HPLF proliferation significantly increased on the TiO(2)-coated disks compared with the uncoated disks and depended upon the coated film thickness. CONCLUSION: An anatase TiO(2)-coated surface under UV irradiation markedly improves the initial response of human fibroblasts.


Assuntos
Materiais Biocompatíveis , Dente Suporte , Implantes Dentários , Fibroblastos/fisiologia , Titânio , Células Cultivadas , Humanos , Propriedades de Superfície , Raios Ultravioleta
6.
Mol Med Rep ; 2(3): 359-63, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-21475837

RESUMO

Prostaglandin E2 (PGE2) is an important modulator of cytokine-driven inflammation. Using GeneChip analysis, we found that interleukin (IL)-1ß induces the gene expression of PTGER4, which encodes the PGE2 receptor subtype EP4 (PGE2EP4). This subtype is one of four PGE2 receptors occurring in synoviocyte MH7A cells. Immunofluorescence microscopy revealed a corresponding upregulation in the production of PGE2EP4 protein in IL-1ß-pretreated MH7A cells. PGE2 alone has no effect on IL-8 production, but in cells pretreated with IL-1ß it markedly enhances IL-8 production. Moreover, a stimulatory effect of PGE2 on IL-8 production in the synoviocyte MH7A cells was observed. These results indicate that, in the synovial tissues of patients with rheumatoid arthritis, PGE2 stimulates the release of IL-8 from the fibroblastic cells classified as present, thereby exacerbating inflammation.

7.
Nihon Hotetsu Shika Gakkai Zasshi ; 52(3): 366-74, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18678970

RESUMO

PURPOSE: Bone marrow stromal cells (BMSCs) are a promising cell source in applications for tissue engineering and regenerative medicine. Optimization and control of the growth and differentiation of cultivated cells can be achieved by the administration of growth factors and hormones in vitro. This study provided experimental information on the enhancement of the osteogenic potential of rat BMSCs in vitro and in vivo. METHODS: Mineralized nodule formation of rat BMSCs in culture for 3 weeks with dexamethasone (Dex)-treated media supplemented with both basic fibroblast growth factor (bFGF) and 17beta -estradiol (E2) was examined by histology. In porous beta-tricalcium phosphate (beta - TCP), proliferation, migration, and differentiation of BMSCs were examined by histology and transmission electron microscopy. After culturing, the composites were subcutaneously implanted into syngeneic rats. The tissues with implants were harvested after 4 weeks and evaluated microscopically by using histological stain. RESULTS: Dex-treated media supplemented with both bFGF and E2 was the most effective in mineralized nodule formation of BMSCs in vitro. Light and electron microscopy revealed the presence of many cells with developed rough endoplasmic reticulum. Bone formation in the BMSC/beta -TCP composites in cultures in vitro for 3 weeks was observed histologically at 4 weeks after implantation. When BMSC/beta -TCP composites were cultured in Dex-treated media supplemented with both bFGF and E2, the amount of bone formation at implants was substantially greater than that of composites cultured in Dex-treated media supplemented with bFGF. CONCLUSION: The combined use of bFGF and E2 could effectively improve the bone-forming ability of BMSCs.


Assuntos
Células da Medula Óssea/fisiologia , Dexametasona/farmacologia , Estradiol/farmacologia , Fator 2 de Crescimento de Fibroblastos/farmacologia , Osteogênese/efeitos dos fármacos , Células Estromais/fisiologia , Animais , Fosfatos de Cálcio , Células Cultivadas , Sinergismo Farmacológico , Masculino , Ratos , Ratos Endogâmicos F344 , Estimulação Química , Células Estromais/transplante
8.
FEMS Yeast Res ; 8(5): 706-14, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18399986

RESUMO

The development of fermentative yeasts secreting no organic acids is highly desirable for ethanol production coupled with membrane separation processes, because the acidic byproduct, succinic acid, significantly inhibits the membrane permeation of ethanol. Of the Pichia and Candida yeasts tested, Candida krusei IA-1 showed the highest ethanol productivity [55 g L(-1) day(-1) from 150 g L(-1) (w/v) of glucose], comparable to the strains of Saccharomyces cerevisiae, and produced much less of the acid (0.6 g L(-1) day(-1)) than the Saccharomyces strains (1.5-1.8 g L(-1) day(-1)) under semi-aerobic conditions. Interestingly, under aerobic conditions, strain IA-1 showed no production of the acid. Stain IA-1 exhibited a good assimilation of the acid, while S. cerevisiae NBRC 0216 showed no assimilation. The activity of succinate dehydrogenase (SDH) in strain IA-1 was 37.5 mU mg(-1), and 7.8-fold higher than that in S. cerevisiae strain NBRC 0216. More significantly, SDH1 was abundantly transcribed in strain IA-1, different from that in strain NBRC 0216, regardless of the culture conditions. From these results, C. krusei IA-1 efficiently takes up succinic acid and metabolizes it in the Krebs cycle, producing an extremely low level of byproducts in the culture medium. Therefore, C. krusei is not only a promising alternative to S. cerevisiae but also a suitable model for metabolic engineering of S. cerevisiae.


Assuntos
Candida/metabolismo , Etanol/metabolismo , Ácido Succínico/metabolismo , Aerobiose , Anaerobiose , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Perfilação da Expressão Gênica , Microbiologia Industrial , Redes e Vias Metabólicas , Modelos Biológicos , Dados de Sequência Molecular , Pichia/metabolismo , Saccharomyces cerevisiae/metabolismo , Análise de Sequência de DNA , Succinato Desidrogenase/genética , Succinato Desidrogenase/metabolismo
9.
Chemistry ; 12(9): 2434-40, 2006 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-16374891

RESUMO

Self-assembling properties of "natural" glycolipid biosurfactants, mannosyl-erythritol lipids A and B (MEL-A, MEL-B), which are abundantly produced from yeast strains, were investigated by using the fluorescence-probe method, dynamic light-scattering (DLS) analysis, freeze-fracture transmission electron microscopy (FF-TEM), and synchrotron small/wide-angle X-ray scattering (SAXS/WAXS) analysis, among other methods. Both MEL-A and MEL-B exhibit excellent self-assembly properties at extremely low concentrations; they self-assemble into large unilamellar vesicles (LUV) just above their critical-aggregation concentration (CAC). The CAC(I) value was found to be 4.0x10(-6) M for MEL-A and 6.0x10(-6) M for MEL-B. Moreover, the self-assembled structure of MEL-A above a CAC(II) value of 2.0x10(-5) M was found to drastically change into sponge structures (L3) composed of a network of randomly connected bilayers that are usually obtained from a complicated multicomponent "synthetic" surfactant system. Interestingly, the average water-channel diameter of the sponge structure was 100 nm. This is relatively large compared with those obtained from "synthetic" surfactant systems. In addition, MEL-B, which has a hydroxyl group at the C-4' position on mannose instead of an acetyl group, gives only one CAC; the self-assembled structure of MEL-B seems to gradually move from LUV to multilamellar vesicles (MLV) with lattice constants of 4.4 nm, depending on the concentration. Furthermore, the lyotropic-liquid-crystal-phase observation at high concentrations demonstrates the formation of an inverted hexagonal phase (H2) for MEL-A, together with a lamella phase (L(alpha)) for MEL-B, indicating a difference between MEL-A and MEL-B molecules in the spontaneous curvature of the assemblies. These results clearly show that the difference in spontaneous curvature caused by the single acetyl group on the head group probably decides the direction of self-assembly of glycolipid biosurfactants. The unique and complex molecular structures with several chiral centers that are molecularly engineered by microorganisms must have led to the sophisticated self-assembling properties of the glycolipid biosurfactants.


Assuntos
Glicolipídeos/química , Tensoativos/química , Técnicas de Química Analítica/instrumentação , Técnicas de Química Analítica/métodos , Substâncias Macromoleculares/química , Transição de Fase
10.
Tissue Eng ; 11(9-10): 1346-55, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16259590

RESUMO

We studied the effects of dexamethasone (Dex) and basic fibroblast growth factor (bFGF) on proliferation and differentiation of rat bone marrow stromal cells (RBMSCs), using three scaffolds: collagen sponge, poly(glycolic acid) (PGA)-collagen sponge, and PGA-collagen (UV) sponge. RBMSCs were seeded into the sponges, and cultured in primary medium, primary medium with Dex, and primary medium with bFGF and Dex. Three weeks after cultivation, we examined alkaline phosphatase (ALP) activity and cell number in the sponges, and also performed macroscopic, light microscopic, and scanning electron microscopic (SEM) observations. Collagen sponge shrank considerably, but PGA-collagen and PGA-collagen (UV) sponges maintained most of their original shape. PGA-collagen (UV) sponge supplemented with bFGF and Dex together had the highest ALP activity and cell number, followed by PGA-collagen sponge. Although collagen sponge showed cell proliferation only on the surface, the other two sponges showed cell proliferation in the interior. SEM showed the best cell attachment to PGA-collagen (UV) sponge in the presence of bFGF and Dex, followed by PGA-collagen sponge. In conclusion, PGA-collagen (UV) and PGA-collagen sponges proved to be much more useful as scaffolding for bone regeneration when combined with bFGF and Dex.


Assuntos
Diferenciação Celular , Proliferação de Células , Ácido Poliglicólico/química , Células Estromais/citologia , Células Estromais/fisiologia , Engenharia Tecidual/métodos , Fosfatase Alcalina/metabolismo , Animais , Anti-Inflamatórios/farmacologia , Células da Medula Óssea/citologia , Regeneração Óssea , Adesão Celular , Contagem de Células , Técnicas de Cultura de Células , Células Cultivadas , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/efeitos da radiação , Colágeno Tipo I/química , Colágeno Tipo I/efeitos da radiação , Colágeno Tipo I/ultraestrutura , Dexametasona/farmacologia , Combinação de Medicamentos , Fator 2 de Crescimento de Fibroblastos/farmacologia , Masculino , Microscopia Eletrônica de Varredura , Ácido Poliglicólico/efeitos da radiação , Ratos , Ratos Endogâmicos F344 , Células Estromais/efeitos dos fármacos , Células Estromais/enzimologia , Células Estromais/metabolismo , Células Estromais/ultraestrutura , Suínos , Tendões/química , Raios Ultravioleta
11.
Dent Mater J ; 23(4): 585-92, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15688723

RESUMO

The purpose of this study was to evaluate the durability of tubules occluded with FTLA treatment by toothbrush abrasion test on the applied surface and by measuring fluoride release from the FTLA components. Dentin specimens with simulated hypersensitive surfaces were treated with APF containing tannic acid. After which, the specimens received lanthanum-chloride-with-powdered-fluoroapatite-glass-ceramics treatment. The specimens were subjected to toothbrush abrasion test up to 6,000 strokes. SEM observation revealed that dentinal tubules of the FTLA treated specimens were completely occluded with fine deposits even after toothbrush abrasion of 6,000 strokes. EPMA analysis revealed that fluoride, lanthanum, and aluminum were the main FTLA components on the dentin surface after 6,000-stroke abrasion. To measure fluoride release from the FTLA components, a slurry was enclosed in a cellulose tube and suspended in deionized water at 37 degrees C. After fluoride was dialyzed against deionized water, a high concentration of fluoride was found to be released from FTLA the components, indicating FTLA treatment's prominent durability. These results suggested that FTLA treatment has a superior resistance against toothbrush abrasion and a high fluoride-releasing performance. These characteristics lend much weight to showing that the FTLA method is an effective and durable medicament for dentin hypersensitivity.


Assuntos
Fluoreto de Fosfato Acidulado/uso terapêutico , Sensibilidade da Dentina/tratamento farmacológico , Fluoretos Tópicos/uso terapêutico , Fluoretos/uso terapêutico , Lantânio/uso terapêutico , Análise de Variância , Animais , Apatitas , Bovinos , Cerâmica , Permeabilidade da Dentina/efeitos dos fármacos , Sensibilidade da Dentina/diagnóstico , Microanálise por Sonda Eletrônica , Fluoretos/análise , Fluoretos/farmacologia , Fluoretos Tópicos/farmacologia , Lantânio/farmacologia , Estatísticas não Paramétricas , Abrasão Dentária , Escovação Dentária
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...