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1.
J Plant Res ; 134(5): 1139-1148, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34142247

RESUMEN

It is known that rice roots take up cadmium (Cd) via the symplastic route mediated by membrane-bound mineral transporters. Here we provide evidence that apoplastic bypass flow is another Cd uptake route in rice. High concentrations of Cd rendered apoplastic bypass flow rate increased in rice seedlings. These concentrations of Cd compromised membrane integrity in the root meristem and transition zone. Polyethleneglycol and proline inhibited the Cd-induced apoplastic bypass flow and Cd transfer to the shoots. Loss-of-function mutant of the Cd uptake transporter, nramp5, showed Cd transport to the shoot comparable to the wild type. At a low Cd concentration, increased apoplastic bypass flow rate by NaCl stress resulted in an elevation of Cd transport to shoots both in the wildtype and nramp5. These observations indicate that apoplastic bypass flow in roots carries Cd transport leading to xylem loading of Cd in addition to the symplastic pathway mediated by mineral transporters under stressed conditions.


Asunto(s)
Cadmio , Oryza , Transporte Biológico , Oryza/genética , Raíces de Plantas , Plantones
2.
Plant Cell Physiol ; 61(3): 470-480, 2020 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-31722408

RESUMEN

Regulation of the stability and the quality of mitochondrial RNA is essential for the maintenance of mitochondrial and cellular functions in eukaryotes. We have previously reported that the eukaryotic poly(A)-specific ribonuclease (PARN) and the prokaryotic poly(A) polymerase encoded by AHG2 and AGS1, respectively, coordinately regulate the poly(A) status and the stability of mitochondrial mRNA in Arabidopsis. Mitochondrial function of PARN has not been reported in any other eukaryotes. To know how much this PARN-based mitochondrial mRNA regulation is conserved among plants, we studied the AHG2 and AGS1 counterparts of the liverwort, Marchantia polymorpha, a member of basal land plant lineage. We found that M. polymorpha has one ortholog each for AHG2 and AGS1, named MpAHG2 and MpAGS1, respectively. Their Citrine-fused proteins were detected in mitochondria of the liverwort. Molecular genetic analysis showed that MpAHG2 is essential and functionally interacts with MpAGS1 as observed in Arabidopsis. A recombinant MpAHG2 protein had a deadenylase activity in vitro. Overexpression of MpAGS1 and the reduced expression of MpAHG2 caused an accumulation of polyadenylated Mpcox1 mRNA. Furthermore, MpAHG2 suppressed Arabidopsis ahg2-1 mutant phenotype. These results suggest that the PARN-based mitochondrial mRNA regulatory system is conserved in land plants.


Asunto(s)
Embryophyta/genética , Embryophyta/metabolismo , Exorribonucleasas/genética , Exorribonucleasas/metabolismo , Poli A/metabolismo , ARN Mensajero/metabolismo , ARN Mitocondrial/metabolismo , Arabidopsis/enzimología , Arabidopsis/genética , Arabidopsis/metabolismo , Embryophyta/enzimología , Regulación de la Expresión Génica de las Plantas , Marchantia/genética , Marchantia/metabolismo , Mitocondrias/metabolismo , Fenotipo , Plantas Modificadas Genéticamente/genética , Transcriptoma
3.
Sensors (Basel) ; 19(14)2019 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-31295953

RESUMEN

Paper-based sensors fabricated using the pencil-on-paper method are expected to find wide usage in many fields owing to their low cost and high reproducibility. Here, hydrogen (H2) detection was realized by applying palladium (Pd) nanoparticles (NPs) to electronic circuits printed on paper using a metal mask and a pencil. We confirmed that multilayered graphene was produced by the pencil, and then characterized Pd NPs were added to the pencil marks. To evaluate the gas-sensing ability of the sensor, its sensitivities and reaction rates in the presence and absence of H2 were measured. In addition, sensing tests performed over a wide range of H2 concentrations confirmed that the sensor had a detection limit as low as 1 ppm. Furthermore, the sensor reacted within approximately 50 s at all H2 concentrations tested. The recovery time of the sensor was 32 s at 1 ppm and 78 s at 1000 ppm. Sensing tests were also performed using Pd NPs of different sizes to elucidate the relationship between the sensing rate and catalyst size. The experimental results confirmed the possibility of fabricating paper-based gas sensors with a superior sensing capability and response rate.

4.
Sensors (Basel) ; 18(12)2018 Dec 03.
Artículo en Inglés | MEDLINE | ID: mdl-30513867

RESUMEN

The possibility of exposure to botulinum neurotoxin (BoNT), a powerful and potential bioterrorism agent, is considered to be ever increasing. The current gold-standard assay, live-mouse lethality, exhibits high sensitivity but has limitations including long assay times, whereas other assays evince rapidity but lack factors such as real-time monitoring or portability. In this study, we aimed to devise a novel detection system that could detect BoNT at below-nanomolar concentrations in the form of a stretchable biosensor. We used a field-effect transistor with a p-type channel and electrodes, along with a channel comprising aligned carbon nanotube layers to detect the type E light chain of BoNT (BoNT/E-Lc). The detection of BoNT/E-Lc entailed observing the cleavage of a unique peptide and the specific bonding between BoNT/E-Lc and antibody BoNT/E-Lc (Anti-BoNT/E-Lc). The unique peptide was cleaved by 60 pM BoNT/E-Lc; notably, 52 fM BoNT/E-Lc was detected within 1 min in the device with the antibody in the bent state. These results demonstrated that an all-carbon nanotube-based device (all-CNT-based device) could be produced without a complicated fabrication process and could be used as a biosensor with high sensitivity, suggesting its potential development as a wearable BoNT biosensor.


Asunto(s)
Técnicas Biosensibles , Toxinas Botulínicas/aislamiento & purificación , Péptidos/aislamiento & purificación , Animales , Anticuerpos Monoclonales/química , Bioterrorismo/tendencias , Toxinas Botulínicas/química , Toxinas Botulínicas/toxicidad , Humanos , Ratones , Nanotubos de Carbono/química , Péptidos/química
5.
J Nanosci Nanotechnol ; 11(2): 1434-7, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21456206

RESUMEN

CuInS2 powders have been successfully prepared by simple heating a mixture of copper nitrate, indium nitrate and thiourea in ethylene glycol. The prepared powders were fully characterized by SEM, XRD and UV-Vis spectroscopy. The particle shape of the powders obtained with an optimal condition showed spherical shape with about 50 nm in size. The XRD results showed more enhanced crystallized CuInS2 with chalcopyrite structure with increasing reaction time. The values in band-gap energy of nano-sized CuInS2 powders would be estimated 1.63 eV, blue-shifted from that of micron-sized powders due to size quantization effect.

6.
J Nanosci Nanotechnol ; 8(10): 5316-20, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19198446

RESUMEN

One-dimensional (1-D) layered titanate nanotubes and nanoribbon thin films were prepared via the hydrothermal reaction of Ti metal flakes with concentrated NaOH solution. TEM, SEM, and XRD studies of the reaction products revealed that 20-nm-wide and about 1-microm-long nanoribbons formed in 5 M NaOH aqueous solution at 140 degrees C for 12 h, while 6 aproximately 8-nm-wide and several hundred-nanometer-long nanotubes formed with 10 M NaOH. The effect of post treatments on the thermal stablity, phase structure and morphology of the as-prepared nanotubes films was investigated. Different morphologies and crystallinity changes of the as-prepared nanotubes films during heat treatment process are attributed to the sodium impurity.

7.
J Nanosci Nanotechnol ; 8(10): 5158-61, 2008 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19198411

RESUMEN

In this study, various sized and shaped titanates were prepared using rutile phase TiO2 nano-powders in strong basic solution of NaOH having various metallic ions as chlorides by hydrothermal process. Obtained powders were fully characterized using SEM, TEM, XRD, and BET. The XRD results show that all obtained powders have layered structure. However, the shapes of particles doped with Zr4+ and Li+ show nano-belt and nano-plate, respectively, compared to those with nano-tubes of undoped, Ni2+ and Fe3+ doped. These results suggest that particle shape of titanates can be controlled only by small amount of doping elements in NaOH aqueous solutions.

8.
Arch Pharm Res ; 31(11): 1517-23, 2008 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19023550

RESUMEN

This study examined the effects of ketorolac tromethamine (KT) and baicalein (BE) on the levels of inflammatory factors in human synoviocytes. The fibroblast-like synoviocytes (FLS) cells were used to determine the possible regulatory effects of KT and BE (KTBE) on the levels of inflammatory factors in FLS cells. In addition, the levels of TNF-alpha, IL-6, and IL-1beta mRNA expression in FLS cells induced by a TNF-alpha and IL-1beta co-treatment were largely inhibited by a KTBE treatment. The level of FLS cells proliferation was increased by IL-1beta and TNF-alpha, and strongly inhibited by KTBE treatment. The production of oxygen species (ROS) was inhibited by KTBE in FLS cells. KTBE appears to regulate the levels of mRNA that are important for regulating RA progression.


Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Flavanonas/farmacología , Mediadores de Inflamación/metabolismo , Ketorolaco Trometamina/farmacología , Antagonistas de Prostaglandina/farmacología , Líquido Sinovial/metabolismo , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Humanos , Interleucina-1beta/biosíntesis , Interleucina-6/biosíntesis , ARN Mensajero/biosíntesis , ARN Mensajero/aislamiento & purificación , Especies Reactivas de Oxígeno/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Espectrometría de Fluorescencia , Líquido Sinovial/citología , Líquido Sinovial/efectos de los fármacos , Factor de Necrosis Tumoral alfa/biosíntesis
9.
J Exerc Nutrition Biochem ; 22(1): 1-8, 2018 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-29673238

RESUMEN

PURPOSE: We investigated whether treadmill exercise (TE)-induced neuroprotection was associated with enhanced autophagy and reduced apoptosis in a mouse model of pharmacologically induced Parkinson's disease (PD). METHODS: PD was induced via the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). C57BL/6 male mice were randomly assigned to the following three groups: control (C57BL, n=10), MPTP with probenecid (MPTP/C, n=10), and MPTP/ C plus exercise (MPTP-TE, n=10). The MPTP-TE mice performed TE training (10 m/min, 60 min/day, 5 days/week) for 8 weeks. The rotarod test was used to assess motor function. RESULTS: TE restored MPTP/P-induced motor dysfunctionand increased tyrosine hydroxylase levels. Furthermore, TE diminished the levels of α-synuclein (α-syn), a neurotoxin; modulated the levels of autophagy-associated proteins, including microtubule-associated protein 1 light chain 3-II, p62, BECLIN1, BNIP3, and lysosomal-associated membrane protein-2, which enhanced autophagy; inhibited the activation of proapoptotic proteins (caspase-3 and BAX);and upregulated BCL-2, an antiapoptosis protein. CONCLUSION: Taken together, these results suggested that the TE-induced neuroprotection against MPTP-induced cell death was associated with enhanced autophagy and neuronal regeneration based on the findings of inhibited proapoptotic events in the brains of the TE-trained animals.

10.
Oncotarget ; 8(1): 1213-1225, 2017 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-27901484

RESUMEN

Pexa-Vec (pexastimogene devacirpvec; JX-594) has emerged as an attractive tool in oncolytic virotherapy. Pexa-Vec demonstrates oncolytic and immunotherapeutic mechanisms of action. But the determinants of resistance to Pexa-Vec are mostly unknown. We treated hemoatologic malignant cells with Pexa-Vec and examined the gene-expression pattern of sensitive and resistant cells. Human myeloid malignant cell lines (RPMI-8226, IM-9, K562, THP-1) and lymphoid cancer cell lines (MOLT4, CCRF-CEM, Ramos, U937) were treated with Pexa-Vec. Pexa-Vec was cytotoxic on myeloid cell lines in a dose-dependent manner, and fluorescent imaging and qPCR revealed that Pexa-Vec expression was low in RAMOS than IM-9 after 24 hrs and 48 hrs of infection. Gene expression profiles between two groups were analyzed by microarray. Genes with at least 2-fold increase or decrease in their expression were identified. A total of 660 genes were up-regulated and 776 genes were down-regulated in lymphoid cancer cell lines. The up- and down-regulated genes were categorized into 319 functional gene clusters. We identified the top 10 up-regulated genes in lymphoid cells. Among them three human genes (LEF1, STAMBPL1, and SLFN11) strongly correlated with viral replication. Up-regulation of PVRIG, LPP, CECR1, Arhgef6, IRX3, IGFBP2, CD1d were related to resistant to Pexa-Vec. In conclusion, lymphoid malignant cells are resistant to Pexa-Vec and displayed up-regulated genes associated with resistance to oncolytic viral therapy. These data provide potential targets to overcome resistance, and suggest that molecular assays may be useful in selecting patients for further clinical trials with Pexa-Vec.


Asunto(s)
Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Neoplasias Hematológicas/genética , Biomarcadores de Tumor , Línea Celular Tumoral , Efecto Citopatogénico Viral/genética , Vectores Genéticos/genética , Neoplasias Hematológicas/terapia , Humanos , Viroterapia Oncolítica , Virus Oncolíticos/genética , Transcriptoma , Virus Vaccinia/genética
11.
Neuroscience ; 356: 102-113, 2017 07 25.
Artículo en Inglés | MEDLINE | ID: mdl-28527958

RESUMEN

Parkinson's disease (PD) is characterized by progressive dopamine depletion and a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Treadmill exercise is a promising non-pharmacological approach for reducing the risk of PD and other neuroinflammatory disorders, such as Alzheimer's disease. The goal of this study was to investigate the effects of treadmill exercise on α-synuclein-induced neuroinflammation and neuronal cell death in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. Eight weeks of treadmill exercise improved motor deficits and reduced α-synuclein expression, a major causative factor of PD-like symptoms, in MPTP mice. Treadmill exercise also down-regulated the expression of toll-like receptor 2 and its associated downstream signaling molecules, including myeloid differentiation factor-88, tumor necrosis factor receptor-associated factor 6, and transforming growth factor-ß-activated protein kinase 1. These effects were associated with reduced ionized calcium-binding adapter molecule 1 expression, decreased IκBα and nuclear transcription factor-κB phosphorylation, decreased tumor necrosis factor α and interleukin-1ß expression, and decreased NADPH oxidase subunit expression in the SNpc and striatum. Additionally, it promoted the expression of tyrosine hydroxylase and the dopamine transporter, as well as plasma dopamine levels, in MPTP mice; these effects were associated with decreased caspase-3 expression and cleavage, as well as increased Bcl-2 expression in the SNpc. Taken together, our data suggest that treadmill exercise improves MPTP-associated motor deficits by exerting neuroprotective effects in the SNpc and striatum, supporting the notion that treadmill exercise is useful as a non-pharmacological tool for the management of PD.


Asunto(s)
Factor 88 de Diferenciación Mieloide/metabolismo , FN-kappa B/metabolismo , Enfermedad de Parkinson/metabolismo , Transducción de Señal/efectos de los fármacos , Receptor Toll-Like 2/metabolismo , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina/farmacología , Animales , Cuerpo Estriado/metabolismo , Modelos Animales de Enfermedad , Neuronas Dopaminérgicas/efectos de los fármacos , Masculino , Ratones Endogámicos C57BL , Fármacos Neuroprotectores/farmacología , Enfermedad de Parkinson/patología , Condicionamiento Físico Animal , Sustancia Negra/efectos de los fármacos , alfa-Sinucleína/metabolismo
12.
Artículo en Inglés | MEDLINE | ID: mdl-25961674

RESUMEN

Physicians for ordinary people in Korea's Joseon Dynasty (1392-1910) did not need to pass the national medical licensing examination. They were able to work after a sufficient apprenticeship period. Only physician officers were licensed as technical civil servants. These physician officers were middle class, located socially between the nobility and the commoner. They had to pass a national licensing examination to be considered for high-ranking physician officer positions, that is, those at the rank equal to or above the 6th level out of a total of 9 ranks, where the first rank was highest. Royal physicians also had to pass this examination before accepting responsibility for the King's healthcare. This article aims to describe the world of physician officers during the Joseon Dynasty. Physician officers enjoyed considerable social status because they dealt with matters of life and death. Owing to the professional nature of their fields and a strong sense of group identity, they came to compose a distinct social class. The physician officers' world was marked by strong group allegiances based on shared professional knowledge; the use of marriage to gain and maintain social status; and the establishment of hereditary technical posts within the medical profession that were handed down from one generation to the next. The medical licensing examination persisted until 1894 when the civil service examination agency, of which it was part, was abolished. Until that time, the testing agency, the number of candidates who were accepted, two-step test procedures, and the method of test item selection were maintained and enforced.

13.
J Nanosci Nanotechnol ; 15(11): 8711-5, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26726581

RESUMEN

Carbon nanofibers (CNFs) are good candidates for nano-system applications because they have the excellent mechanical and the electrical properties. The mechanical and electrical properties of a single CNF were measured. A tensile test and a measurement of the electrical resistance of CNFs during elongation were performed inside a scanning electron microscope. We confirmed that the CNFs used in this experiment consisted of a polycrystalline structure and an amorphous phase by a result of Raman. Additionally, we observed that the crystal structure in nanofibers exhibits brittle fracture behavior and the amorphous phase make them relatively ductile. The elastic moduli of the CNFs were 9.57 to 13.6 GPa in the elastic section. The electrical resistance of the CNFs exhibited unusual behavior during elongation. The electrical resistance of the CNFs exhibited stable resistance increase like as the tensile results in the initial region. But the electrical resistance exhibited generally irregular increase after initial region because of the polycrystalline structure and amorphous phase. The strain sensitivity of the CNFs exhibited a much lower value.

14.
J Nanosci Nanotechnol ; 15(11): 9071-6, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26726645

RESUMEN

Large-scale graphene or carbon nanotube (CNT) films are good candidates for transparent flexible electrodes, and the strong interest in graphene and CNT films has motivated the scalable production of a good-conductivity and an optically transmitting film. Unzipping techniques for converting CNTs to graphene are especially worthy of notice. Here, we performed nanotube unzipping of the spun multi-walled carbon nanotubes (MWCNTs) to produce networked graphene nanoribbon (GNR) sheet films using an 02 plasma etching method, after which we produced the spun MWCNT film by continually pulling MWCNTs down from the vertical well aligned MWCNTs on the substrate. The electrical resistance was slightly decreased and the optical transmittance was significantly increased when the spun MWCNT films were etched for 20 min by O2 plasma of 100 mA. Plasma etching for the optimized time, which does not change the thickness of the spun MWCNT films, improved the electrical resistance and the optical transmittance.

15.
J Exerc Nutrition Biochem ; 17(4): 151-60, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25566426

RESUMEN

(AD). Although physical exercise and AD have received attention in the scientific literature, the mechanism through which treadmill exercise may impact the brain insulin signaling of AD has not been elucidated. This study aimed to evaluate the neuroprotective effects of treadmill exercise on apoptotic factors (Bcl-2/Bax ratio, caspase-3), HSP70, COX-2, BDNF and PI3-K/Akt signaling pathway in the cortex of NSE/hPS2m transgenic mice model of AD. Treadmill exercise ameliorated cognitive function in water maze test and significantly increased the level of Bcl-2/Bax ratio and HSP-70 in Tg-exe group compared to Tg-con group; on the other hand, it significantly decreased the expression of caspase-3 and COX-2 in Tg-exe group compared to Tg-con group. In addition, treadmill exercise significantly increased the expression of BDNF and PI3K/Akt in Tg-exe group compared to Tg-con group. Consequently, treadmill exercise improves cognitive function possibly via activating neurotrophic factor, BDNF and PI3k/Akt signaling pathway, and Aß-induced neuronal cell death in the cortex of Tg mice was markedly suppressed following treadmill exercise. These results suggest that treadmill exercise may be beneficial in preventing or treating Alzheimer's disease.

16.
Nanoscale Res Lett ; 5(11): 1846-1851, 2010 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-21124625

RESUMEN

The functional silica/polyamide-imide composite films were prepared via simple ultrasonic blending, after the silica nanoparticles were modified by cationic surfactant-cetyltrimethyl ammonium bromide (CTAB). The composite films were characterized by scanning electron microscope (SEM), thermo gravimetric analysis (TGA) and thermomechanical analysis (TMA). CTAB-modified silica nanoparticles were well dispersed in the polyamide-imide matrix, and the amount of silica nanoparticles to PAI was investigated to be from 2 to 10 wt%. Especially, the coefficients of thermal expansion (CET) continuously decreased with the amount of silica particles increasing. The high thermal stability and low coefficient of thermal expansion showed that the nanocomposite films can be widely used in the enamel wire industry.

17.
Biol Pharm Bull ; 28(5): 921-4, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-15863908

RESUMEN

The AIP1 fraction, a small water-soluble fraction purified from Artemisia iwayomogi, was shown to increase antibody production and suppress transplanted tumor cell growth in mice. In order to understand its immuno-modulating activity, we have examined the effect of the AIP1 on mouse thymocytes in vitro. Treatment of mouse thymocytes in culture with the fraction resulted in the suppression of the cell death and the extension of the cell survival. A mouse gene array provided a profile of gene expression change showing the pattern of up- and down-regulated genes by the AIP1 treatment, suggesting that the Fas/FasL-dependent apoptosis pathway might be modulated by the fraction.


Asunto(s)
Apoptosis/efectos de los fármacos , Artemisia , Regulación hacia Abajo/efectos de los fármacos , Glicoproteínas de Membrana/biosíntesis , Factores de Necrosis Tumoral/biosíntesis , Animales , Apoptosis/fisiología , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Células Cultivadas , Fraccionamiento Químico , Regulación hacia Abajo/fisiología , Proteína Ligando Fas , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/fisiología , Factores Inmunológicos/aislamiento & purificación , Factores Inmunológicos/fisiología , Glicoproteínas de Membrana/antagonistas & inhibidores , Ratones , Ratones Endogámicos BALB C , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/farmacología , Hojas de la Planta/química , Solubilidad , Inhibidores del Factor de Necrosis Tumoral , Agua
18.
Biotechnol Lett ; 27(4): 253-7, 2005 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-15742146

RESUMEN

Apoptotic death of mouse thymocytes in vitro, as induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), involves the up-regulation of Fas gene expression, while a carbohydrate fraction, AIP1, from Artemisia iwayomogi suppresses the death of thymocytes in culture along with the down-regulation of Fas gene expression. We have now investigated whether the AIP1 fraction modulates TCDD-induced thymocyte death. When treated with TCDD and AIP1 fraction together, the thymocytes do not show apoptosis induced by the TCDD treatment. The AIP1 supplementation to the TCDD treatment also down-regulates the TCDD-induced Fas gene up-regulation. These findings indicate that the AIP1 fraction suppresses TCDD-induced thymocyte apoptosis through the modulation of Fas gene expression.


Asunto(s)
Apoptosis/efectos de los fármacos , Artemisia/metabolismo , Carbohidratos/farmacología , Dioxinas/farmacología , Receptores del Factor de Necrosis Tumoral/metabolismo , Timo/metabolismo , Animales , Apoptosis/fisiología , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo/efectos de los fármacos , Regulación hacia Abajo/fisiología , Interacciones Farmacológicas , Femenino , Ratones , Ratones Endogámicos C57BL , Timo/efectos de los fármacos , Receptor fas
19.
Langmuir ; 20(25): 10838-44, 2004 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-15568831

RESUMEN

Nano rutile, anatase, and bicrystalline (anatase + brookite) titania powders with an average crystal size of below 10 nm are prepared from aqueous TiOCl(2) solution at low temperatures by adjusting pH values of the starting solution and adding different additives. Adding a small amount of octyl phenol poly(ethylene oxide) into aqueous TiOCl(2) solution leads to the change of particle morphologies of obtained nano titania from needlelike to nano spherical rutile crystals. Amorphous-anatase transformation of titania could proceed in liquid-solid reaction at low temperatures, even at room temperature. A formation mechanism of rutile, anatase, and brookite titania was proposed. It is found that H(+) or H(3)O(+) plays a catalytic role in the phase transformation from amorphous to anatase titania and that the presence of a small amount of SO(4)(2)(-) ion is unfavorable to the formation of both rutile and brookite. By carefully adjusting preparation conditions, nano pure anatase with higher surface area, good crystallinity, and a lower recombination rate of photoexcited electrons and holes was obtained. This nano pure anatase showed a very good photocatalytic activity for gas-phase photo-oxidation of benzene.


Asunto(s)
Benceno/química , Cloruros/química , Oxígeno/química , Temperatura , Titanio/química , Benceno/efectos de la radiación , Gases , Concentración de Iones de Hidrógeno , Hidrólisis , Mediciones Luminiscentes/métodos , Oxidación-Reducción , Tamaño de la Partícula , Fotoquímica , Polvos , Soluciones/química , Propiedades de Superficie , Titanio/efectos de la radiación , Rayos Ultravioleta , Agua/química
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