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1.
BMC Ophthalmol ; 22(1): 5, 2022 Jan 03.
Artículo en Inglés | MEDLINE | ID: mdl-34980033

RESUMEN

BACKGROUND: To determine whether it would be effective in predicting the results of the postoperative full-thickness macular hole (FTMH) closure when intraretinal cyst (IRC) is present. METHODS: Case-control study. Patients with idiopathic FTMH who underwent pars plana vitrectomy with internal limiting membrane peeling were retrospectively reviewed. Preoperative spectral-domain optical coherence tomography was undertaken in all patients. The new parameter, macular hole closing factor (MHCF) was defined as the base diameter - (arm length + IRC height) by adding IRC to the existing parameter. After surgery, patients were classified and analyzed according to the type of hole closure and the damage of photoreceptor. RESULTS: Of the 35 patients, 28 (80.00%) had type 1 closure and seven (20.00%) had type 2 closure. There was a significant difference in postoperative BCVA (P < 0.01), base diameter (P = 0.037), arm length (P = 0.045), and IRC height (P = 0.011) between the two groups. In the type 1 closure, they were further divided into two subgroups according to photoreceptor damage, and it was confirmed that there were significant differences in postoperative BCVA (P = 0.045), hole height (P = 0.048), and IRC height (P = 0.046) in the two subgroups. As for the new parameters, a significant difference between the three groups was confirmed (P < 0.01). CONCLUSION: IRC may help predict hole closure along with the known horizontal parameters. Therefore, the new parameter containing both two factors can help predict not only hole closure but also damage to photoreceptors that affects postoperative visual prognosis.


Asunto(s)
Quistes , Perforaciones de la Retina , Estudios de Casos y Controles , Humanos , Perforaciones de la Retina/diagnóstico , Perforaciones de la Retina/cirugía , Estudios Retrospectivos , Tomografía de Coherencia Óptica , Vitrectomía
2.
BMC Ophthalmol ; 21(1): 399, 2021 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-34794403

RESUMEN

BACKGROUND: To identify disease-specific cytokine and growth factor profile differences in the aqueous humor between wet age-related macular degeneration (AMD) patients and age-matched controls and to correlate their levels with the optical coherence tomography (OCT) findings. METHODS: Aqueous humors were obtained from 13 wet AMD eyes and 10 control eyes. Twenty cytokines and growth factors were measured using a RayBio antibody microarray technology in wet AMD and control eyes. RESULTS: The samples obtained from wet AMD patients exhibited a significantly increased expression of MCP-1, MIP-1α, MIP-1ß, and vascular endothelial growth factor (VEGF). Subretinal fluid (SRF) patients showed significantly lower levels of proinflammatory cytokines, such as IL-1α and GM-CSF, than those without SRF. Pigment epithelial detachments (PED) patients showed lower levels of inflammatory cytokines, such as GM-CSF, IFN-γ, and TNF-α, than those without PED. Subretinal tissue (SRT) patients showed a higher level of IFN-γ than those without SRT. Compared with the controls, type 1 macular neovascularization (MNV) patients showed increased levels of MCP-1, MIP-1α, and MIP-1ß, but not VEGF (p = 0.083). However, type 2 MNV patients showed increased levels of MCP-1 and VEGF (p = 0.040 and p = 0.040). CONCLUSION: Inflammatory cytokines varied according to the type of AMD- and OCT-based parameters. Our observation of low levels of VEGF in patients with type 1 MNV implies that the inhibition of VEGF alone appears to be insufficient treatment for these patients and that cytokines such as MCP-1, MIP-1α, and MIP-1ß should be modulated. And the presence of SRF in MNV may be associated with a positive prognosis because we found relatively low levels of proinflammatory cytokines.


Asunto(s)
Humor Acuoso , Degeneración Macular Húmeda , Inhibidores de la Angiogénesis/uso terapéutico , Citocinas , Humanos , Inyecciones Intravítreas , Análisis por Micromatrices , Tomografía de Coherencia Óptica , Factor A de Crecimiento Endotelial Vascular , Degeneración Macular Húmeda/diagnóstico , Degeneración Macular Húmeda/tratamiento farmacológico
3.
J Nanosci Nanotechnol ; 19(3): 1640-1644, 2019 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-30469237

RESUMEN

In this study, ZnO nanorods (NRs) were synthesized using the hydrothermal method, and the effects of annealing temperature (150 °C-600 °C) on morphology, crystallinity, defects states of the NRs, and electrical property of the n-type ZnO NRs/p-type Si heterojunction diodes were investigated. No appreciable changes in the morphology and crystal structure of the ZnO NRs were observed with increasing annealing temperature up to 450 °C. As the temperature increased to 600 °C, the average length and diameter of the NRs decreased due to the partial melting and sintering in the NRs. From the X-ray photoelectron spectroscopy (XPS) results, the concentration of internal oxygen vacancies decreased with increasing annealing temperature to 450 °C due to thermal diffusion of oxygen vacancies to the surface. The electrical conductivity of the NRs increased to 450 °C, which was attributed to the increased crystallinity and low defects concentration (oxygen vacancy) in the NRs. Conversely, the electrical conductivity degraded at 600 °C due to the decreased effective contact area.

4.
J Nanosci Nanotechnol ; 18(9): 6090-6094, 2018 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-29677748

RESUMEN

Controllable TiO2 architectures with different facets play a key role in the adjustment of the surface area and charge recombination efficiency in photocatalysts. In this study, we synthesized anatase TiO2 mesocrystals with diethanolamine (DEA, 0-5 mM) as a nontoxic capping agent to control the facet of subunits using hydrothermal method, and determine the effect of DEA on subunits, by-products, and consequent photocatalytic performance of TiO2 mesocrystals. The pure TiO2 was spindle-like shaped mesocrystal having bipyramidal subunits with high portion of {101} facets. As DEA concentration was increased, the percentage of {001} exposed facet of subunits increased, but the number of subunits was gradually reduced. When a large amount of DEA (≥3 mM) was added, TiO2 exhibited single crystals rather than mesocrystal, probably because the long chain of DEA interfered with the oriented attachment of subunits. The photocatalytic activity of the TiO2 improved at 0.5 mM of DEA due to low charge recombination rate by increasing {001} facet. On the other hand, subsequent deterioration with further increase of DEA was attributed to the increased by-products and reduced the number of subunits despite the increase in specific surface area. These results imply that charge separation efficiency, rather than specific surface area, is highly responsible for the photocatalytic activity of TiO2.

5.
Nanotechnology ; 27(39): 395604, 2016 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-27560359

RESUMEN

Reactive surface-exposed anatase TiO2 (a-TiO2) is highly desirable for applications requiring superior photocatalytic activity. In order to obtain a favorable surface, morphology control of the a-TiO2 using capping agents has been widely investigated. Herein, we systematically study the effects of different F sources (HF, TiF4, and NH4F) as the capping agent on the morphology control and photocatalytic activities of a-TiO2 in a hydrothermal process. When either HF or TiF4 was added, large truncated bipyramids formed with the photocatalytically active {001} facet, whereas the NH4F was not effective for facet control, yielding nanospheres similar to the pure a-TiO2. The morphology changes were related to the decomposition behaviors of the F sources in the solvent material: HF and TiF4 decomposed and supplied F(-) ions before a-TiO2 nucleation, which changed the nucleation rate and growth direction, leading to the resultant a-TiO2 morphology. On the other hand, NH4F supplied F(-) ions after a-TiO2 nucleation and could not change the growth behavior. In terms of the photocatalytic effect, the HF- and TiF4-treated a-TiO2 effectively decomposed ∼90% and ∼80% of methylene blue, respectively, in 1 h, while ∼60% was decomposed for the NH4F-treated a-TiO2. Note that pure a-TiO2 photocatalytically decomposed only ∼10% of methylene blue over the same time. These results pave the way to precise control of the facet of TiO2 through using different capping agents.

6.
Small ; 11(28): 3469-75, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25802061

RESUMEN

The use of ZnO nanorods (NRs) as an effective coordinator and biosensing platform to create bioluminescence resonance energy transfer (BRET) is reported. Herein, a hydrothermal approach is applied to obtain morphologically controlled ZnO NRs, which are directly bound to luciferase (Luc) and carboxy-modified quantum dot (QD) acting as a donor-acceptor pair for BRET. BRET efficiency varies significantly with the geometry of ZnO NRs, which modulates the coordination between hexahistidine-tagged Luc (Luc-His6 ) and QD, owing to the combined effect of the total surface area consisting of (001) and (100) planes and their surface polarities. Unlike typical QD-BRET reactions with metal ions (e.g., zinc ions), a geometry-controlled ZnO NR platform can facilitate the design of surface-initiated BRET sensors without being supplemented by copious metal ions: the geometry-controlled ZnO NR platform can therefore pave the way for nanostructure-based biosensors with enhanced analytical performance.


Asunto(s)
Transferencia Resonante de Energía de Fluorescencia/métodos , Luciferasas de Renilla/química , Mediciones Luminiscentes/métodos , Nanotubos/química , Puntos Cuánticos , Óxido de Zinc/química , Cristalización/métodos , Luz , Ensayo de Materiales , Nanotubos/efectos de la radiación , Nanotubos/ultraestructura , Tamaño de la Partícula , Propiedades de Superficie/efectos de la radiación , Óxido de Zinc/efectos de la radiación
7.
J Nanosci Nanotechnol ; 13(11): 7648-52, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24245308

RESUMEN

We reported the capability of the SnInZnO (TIZO) film, fabricated using the sol-gel process, to act as a channel layer for printed electronics. We varied the sintering temperature to examine the potential of both the material and the process for application at low processing temperatures. The structure of the film sintered at 300 degrees C consisted of amorphous phase and the nanocrystalline structure began to appear locally at 400 degrees C. With increasing sintering temperature, the ratio of the crystalline structure was increased. In addition, the saturation mobility (mu sat) and off current were increased, the I(on)/I(off) was decreased, and the threshold voltage was shifted in the negative direction by increasing the sintering temperature (mu sat of 11.91 cm2 V(-1) s(-1) and 0.11 cm2 V(-1) s(-1) for the 700 degrees C- and 300 degrees C-sintered samples, respectively). This study could encourage in developing cost-effective TIZO TFTs with robust performances.


Asunto(s)
Membranas Artificiales , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Óxidos/química , Transistores Electrónicos , Conductividad Eléctrica , Diseño de Equipo , Análisis de Falla de Equipo , Calor , Sustancias Macromoleculares/química , Ensayo de Materiales , Conformación Molecular , Tamaño de la Partícula , Transición de Fase , Propiedades de Superficie
8.
J Nanosci Nanotechnol ; 13(11): 7774-8, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24245332

RESUMEN

We fabricated InSnZnO (ITZO) thin-film transistors (TFTs) with a high-permittivity (K) ZrO2 gate insulator using a solution process and explored the microstructure and electrical properties. ZrO2 and ITZO (In:Sn:Zn = 2:1:1) precursor solutions were deposited using consecutive spin-coating and drying steps on highly doped p-type Si substrate, followed by annealing at 700 degrees C in ambient air. The ITZO/ZrO2 TFT device showed n-channel depletion mode characteristics, and it possessed a high saturation mobility of approximately 9.8 cm2/V x s, a small subthreshold voltage swing of approximately 2.3 V/decade, and a negative V(TH) of approximately 1.5 V, but a relatively low on/off current ratio of approximately 10(-3). These results were thought to be due to the use of the high-kappa crystallized ZrO2 dielectric (kappa approximately 21.8) as the gate insulator, which could permit low-voltage operation of the solution-processed ITZO TFT devices for applications to high-throughput, low-cost, flexible and transparent electronics.


Asunto(s)
Nanoestructuras/química , Compuestos de Estaño/química , Transistores Electrónicos , Óxido de Zinc/química , Circonio/química , Diseño de Equipo , Análisis de Falla de Equipo , Nanoestructuras/ultraestructura , Tamaño de la Partícula , Soluciones
9.
J Nanosci Nanotechnol ; 12(4): 3350-4, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22849122

RESUMEN

High-k ZrO2/Si films were fabricated by a sol-gel method and the effects of the thickness of ZrO2 on the phase formation, interface chemical structure, and dielectric performance were studied. The 0.1 M precursor sol was prepared by using Zr acetylacetonate, coated, dried on Si substrates, and finally annealed at 500 degrees C. The thickness of ZrO2 was varied in the range from 7 to 51 nm by repeating the coating and drying sequences. The deposited ZrO2 was amorphous for the sample with a thickness of -7 nm, but tetragonal (t-) phases appeared as the thickness increased. As the thickness increased, the flat-band voltage and hysteresis width in the capacitance-voltage curves increased. The sol-gel deposited ZrO2 dielectrics showed a high k value (-33) due to the formation of the t-phase, while retaining gate leakage current levels of less than -4.0 x 10(-5) A/cm2 at 1 MV/cm.

10.
J Nanosci Nanotechnol ; 12(2): 1406-10, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22629967

RESUMEN

C-doped MgB2 wires were fabricated from a polyacrylic acid (PAA) using a conventional in-situ PIT technique. The effects of the PAA content on the lattice parameter, microstructure, critical temperature (Tc) and critical current density (Jc) were examined. With increasing PAA content, the amount of MgO in the sample increased but the crystallinity, a-axis lattice parameter, and Tc of MgB2 wires decreased, indicating that the C that decomposed from PAA during heat treatment had substituted for B. All doped samples exhibited a higher Jc than the undoped sample at high magnetic field, and the Jc(B) property improved with increasing PAA content: for the 7 wt% doped sample, the Jc was approximately 3-times higher than that of the pristine sample (1.28 kA/cm2 vs. 3.43 kA/cm2) at 5 K and 6.6 T. The improved Jc(B) of the doped sample was attributed to the decreased grain size, enlarged lattice distortion and increased C doping level.

11.
J Nanosci Nanotechnol ; 12(7): 5804-7, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22966658

RESUMEN

The optical properties of InGaZnO (IGZO) films grown through the sol-gel process as a function of sintering time were investigated with spectroscopic ellipsometry (SE). The IGZO precursor sol was prepared by mixing In nitrate, Ga nitrate, and Zn acetate at a molar ratio of In:Ga:Zn = 3:1:1. The solution was deposited on a SiO2/Si substrate via spin coating. Sintering was performed at 400 degrees C for 1-15 h in an ambient atmosphere. The optical properties were measured over the range 1.12-6.52 eV via variable angle SE, at room temperature. The angle of incidence was varied from 50 to 70 degrees in 5 degree steps. To extract the pure optical properties of IGZO, multilayer-structure calculation with Tauc-Lorentz dispersion relation for IGZO was performed. The changes in the dielectric function of the IGZO films with varying sintering time were observed. The resultant optical properties can be related to the concentration of oxygen vacancies in the material, which can be controlled by the sintering time.

12.
Environ Technol ; 33(10-12): 1271-8, 2012 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-22856299

RESUMEN

A pilot-scale municipal wastewater treatment plant composed of a fixed film activated sludge (IFAS) system with sulfur-limestone autotrophic denitrification (SLAD) was operated for a year and the influence of different operational factors was investigated. Nitrification efficiency was found to be above 91% at temperatures above 25 degrees C even at short hydraulic residence times (HRTs), but declined to 51 +/- 2% when the temperature dropped to 22 +/- 3 degrees C. The minimum HRT (HRT(min)) to achieve nitrification efficiency > 90% was found to be 12 h at temperatures above 25 degrees C. Denitrification efficiencies were found to be 89% and 79% at a nitrate loading of 0.36 kg NO3(-)-N m(-3) d(-1) and at 0.18 kg NO3(-)-N m(-3) d(-1), respectively. The minimum empty bed residence time (EBRT) to achieve denitrification efficiency above 80% without methanol addition was 3 h at a nitrate loading rate of 0.27-0.38 kg NO3(-)-N m(-3) d(-1). The amount of nitrate removed as a function of the sulfate formed was found to be 0.188 g NO3(-)-N/g SO4(2-). The nitrate load removed by the biofilter as a function of the alkalinity consumed was found to be very close to the theoretical stoichiometric value. The application of the pilot plant was proven to be feasible and the performance of the SLAD system, especially with respect to the minimum EBRT to achieve denitrification efficiency above 80%, the maximum denitrification rate and performance at temperatures below 10 degrees C. To achieve a nitrification efficiency above 90% in the IFAS system, temperature changes and the minimum HRT were found to be the most influential operational parameters.


Asunto(s)
Desnitrificación , Nitrificación , Purificación del Agua/instrumentación , Procesos Autotróficos , Carbonato de Calcio , Estudios de Factibilidad , Filtración , Nitratos/análisis , Proyectos Piloto , Aguas del Alcantarillado , Sulfatos/análisis , Azufre
13.
J Am Coll Health ; 70(8): 2318-2326, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-33522463

RESUMEN

ObjectivesThis study investigates whether recreational marijuana legislation and perceived social norms (descriptive and injunctive) affect college students' propensity to share pro-marijuana messages. We examine which referent group (close friends, typical student, parents) most influence those norms. Participants: A sample of 343 college students participated in the study. Of these students, 214 were from Washington State, where recreational marijuana is legal, and 129 were from Wyoming, where recreational marijuana is illegal. Method: Data, from an online survey, were analyzed through PROCESS analyses. Results: College students in Washington State who believed a typical peer would want them to share pro-marijuana messaging were marginally more likely to share pro-marijuana messages than their counterparts in Wyoming. However, among students who thought a typical peer would not approve of them sharing pro-marijuana messaging, the opposite pattern emerged. Conclusion: Restrictive recreational marijuana legislation does not uniformly abate related message sharing on social media.


Asunto(s)
Cannabis , Medios de Comunicación Sociales , Humanos , Estudiantes , Universidades , Grupo Paritario , Normas Sociales
14.
Medicine (Baltimore) ; 100(46): e27887, 2021 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-34797334

RESUMEN

RATIONALE: We report a case of anisocoria that occurred after contamination with a scopolamine transdermal patch, and introduce a diagnostic approach for anisocoria patients. PATIENT CONCERNS: A 35-year-old woman with no past ophthalmologic history presented to the ophthalmology department complaining of a dilated pupil in the right eye. Corrected visual acuities was 20/20 in both eyes, and the intraocular pressures were 20 and 18 mm Hg in the right and left eye, respectively. The anterior chambers in both eyes were unremarkable on slit-lamp examination. The pupil size was 5.0 mm in the right eye and 2.0 mm in the left eye, and the extraocular muscles of both eyes were intact. DIAGNOSIS: The patient neither did present with facial anhidrosis nor did she present with ptosis. Furthermore, as we did not observe dilatation lag in the smaller pupil, we applied 1% apraclonidine in the left eye in order to rule out Horner syndrome and did not observe dilatation of the pupil. We then applied 0.125% and 1% pilocarpine to exclude oculomotor nerve palsy; however, it could not be ruled out as constriction of pupil to 3.1 mm in the right eye was observed after applying 1% pilocarpine. Moreover, upon further investigation, we discovered that the patient had a scopolamine transdermal patch applied for 2 days prior to the clinic visit. INTERVENTIONS: Artificial tears were administered and the patient was observed and monitored. OUTCOMES: The pupil size in the right eye gradually decreased to 4.5 mm on the second day of observation and to 3.6 mm on the fourth day of observation. LESSONS: A detailed history of the use of medications such as scopolamine patches in patients with unilateral dilated pupils without vision loss is of utmost importance. We report the exclusion of important diseases using pilocarpine and apraclonidine hydrochloride. It was confirmed that improvement naturally occurs over time.


Asunto(s)
Anisocoria/inducido químicamente , Escopolamina/efectos adversos , Parche Transdérmico , Adulto , Anisocoria/diagnóstico , Femenino , Humanos , Imagen por Resonancia Magnética , Pilocarpina , Pupila , Escopolamina/administración & dosificación
15.
Transl Vis Sci Technol ; 10(1): 6, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33505773

RESUMEN

Purpose: To confirm the predictors of postoperative visual outcomes by performing full-field electroretinography (ffERG) before surgery in patients with epiretinal membranes (ERMs). Methods: Sixty-one eyes of patients with ERMs who underwent pars plana vitrectomy with membrane peeling were prospectively reviewed. Correlations between preoperative data (ffERG and optical coherence tomography) and postoperative best-corrected visual acuity (BCVA) were investigated. Receiver operating characteristic (ROC) curve analysis was performed to obtain cutoff values of the ffERG parameters predicting good visual outcome (final BCVA ≥ 20/30). Results: Postoperative BCVA was significantly correlated with the implicit time and amplitude of the b-wave in light-adapted (LA) 3.0 electroretinography (ERG), with the amplitude difference between N1 and P1 in the LA 30-Hz flicker ERG, and with the sum of the amplitudes of OS1, OS2, and OS3 in dark-adapted (DA) oscillatory potential (OP) ERG (P < 0.01). The area under the ROC curve to predict good visual outcome was statistically significant for the four parameters (0.787, 0.815, 0.757, and 0.792, respectively). Conclusions: The postoperative BCVA in patients with ERM was significantly correlated with the implicit time and amplitude of the b-wave in the LA 3.0 ERG, the amplitude difference between N1 and P1 in the LA 30-Hz flicker ERG, and the sum of the amplitudes of OS1, OS2, and OS3 in DA OP ERG of ffERG. It is thought that ffERG before surgery may help predict visual outcomes after surgery. Translational Relevance: It was confirmed that the degree of retinal function in the ERM can predict BCVA after treatment.


Asunto(s)
Membrana Epirretinal , Electrorretinografía , Membrana Epirretinal/cirugía , Humanos , Retina/diagnóstico por imagen , Agudeza Visual , Vitrectomía
16.
Medicine (Baltimore) ; 100(35): e27141, 2021 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-34477167

RESUMEN

ABSTRACT: The aim of this study is to compare the endothelial cell density (ECD) and morphology between diabetic mellitus (DM) and nondiabetic patients at 1 year after phacoemulsification in operated eyes and nonoperated eyes.Evaluation was performed in 28 patients (56 eyes) with type 2 diabetes and 37 patients (74 eyes) without diabetes who underwent 1-year interval cataract surgery. Using a noncontact specular microscope and Scheimpflug rotating camera, corneal parameters were analyzed before and 1 year after surgery. Subgroups analysis was performed based on a disease duration 10 years and HbA1c concentration 7% and Pearson correlation analysis was performed.The mean change in ECD at 1 year after surgery was 13.28% in the DM group and 11.40% in the control group. In the fellow nonoperated eyes, the mean change was 4.47% and 3.63% in the DM and control groups, respectively. There was no significant difference in postoperative ECD, coefficient of variance, hexagonality, and central corneal thickness between 2 groups. In the subgroup analysis, the long disease duration DM group (≥10 years) had a significantly greater ECD loss than the control and short disease duration DM groups (<10 years). Blood urea nitrogen (BUN) showed a significant correlation with postoperative ECD change (r = -0.474, P = .011).The diabetic group with a longer disease duration showed significantly greater ECD decrease compared to the nondiabetic group and BUN correlated with ECD changes after phacoemulsification. Postoperative ECD loss may be high if the disease duration is long or if the BUN level is high.


Asunto(s)
Córnea/patología , Diabetes Mellitus Tipo 2/patología , Células Endoteliales , Facoemulsificación/efectos adversos , Anciano , Catarata/complicaciones , Diabetes Mellitus Tipo 2/complicaciones , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos
17.
Bull Environ Contam Toxicol ; 84(4): 459-64, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20352186

RESUMEN

Soil incubation and germination tests were conducted to assess zerovalent iron (ZVI), organic compost, moisture and their combinations on metolachlor degradation in soil. The ZVI alone degraded 91% of metolachlor in soil within 40 days following bi-phasic kinetics. Organic amendment alone facilitated metolachlor degradation in soil up to 60% after 40 days depending on the amendment rate. However, the combination of ZVI with compost amendment at 30 ton ha(-1) and 30% moisture content accelerated metolachlor degradation to 90% after 3 days and 98% after 40 days. The half life (t (1/2)) of metolachlor degradation with ZVI, compost at 30 ton ha(-1), and 30% moisture was about 1 day, which was faster than ZVI treatment alone and 98% faster than controls. Germination and growth of lettuce (Lactuca sativa) and crabgrass (Digitaria sanguinalis L. Scop.) were severely inhibited in unamended metolachlor-contaminated soils but when these soils were amended with ZVI, germination and growth was comparable to controls (metolachlor free soil). Metolachlor degradation was greatest when ZVI, compost and moisture were used together, suggesting that these treatments will maximize in situ remediation of metolachlor-contaminated soils in the field.


Asunto(s)
Acetamidas/metabolismo , Restauración y Remediación Ambiental/métodos , Herbicidas/metabolismo , Contaminantes del Suelo/metabolismo , Suelo/análisis , Digitaria/metabolismo , Germinación , Hierro/metabolismo , Lactuca/metabolismo , Contaminantes del Suelo/análisis
18.
J Nanosci Nanotechnol ; 9(12): 7402-6, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19908797

RESUMEN

In this report, high-purity nanocrystalline boron powders processed by ball-milling were used as the precursor powders to fabricate MgB2 superconductor. The transport properties and the critical current density in the samples made from ball-milled boron powders and as-supplied boron powders were investigated. It was found that the ball-milled boron powders led to a significant enhancement of the critical current density in MgB2 sintered at 650 degrees C. The reason can be attributed to the small MgB2 grain size caused by the ball-milled boron precursor powders. The resistivity of the samples made from the ball-milled boron powder was lower than that of the sample from as-supplied boron powder. As the sintering temperature increased, both resistivity and upper critical field decreased in the samples using the ball-milled boron powders as a precursor. Poor connectivity and large strain are responsible for the high resistivity.

19.
J Nanosci Nanotechnol ; 9(12): 7477-80, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19908812

RESUMEN

The change in the lattice parameters or the lattice disorder is claimed as a cause of the slight reduction in the transition temperature by carbon doping in MgB2. In this work, an extensive investigation on the effects of carbohydrate doping has been carried out. It is found that not only the a-axis but also the c-axis lattice parameter increases with the sintering temperature. A linear relation between the unit cell volume and the critical temperature is observed. Compared with the well known correlation between the lattice strain and the critical temperature, the X-ray peak broadening itself shows a closer correlation with the transition temperature. The residual resistivity and the critical temperature are linearly correlated with each other as well and its implication is further discussed.

20.
J Nanosci Nanotechnol ; 9(12): 7388-92, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19908794

RESUMEN

We fabricated carbon nanotube (CNT)- and nano-carbon (NC)-doped MgB2 using an in-situ process in order to improve the critical current density (J(c)) at high magnetic field. We then evaluated the effects of the doped carbon content on phase formation, microstructure, and critical properties. CNT had a diameter and length of 5-10 nm and 0.5-1 microm, respectively, and NC was a sphere with a diameter of 5-30 nm. The bulk MgB(2-x)C(x) samples with x = 0, 0.05, and 0.1 for NC and CNT were fabricated by pressing into pellets and then sintered at 900 degrees C for 30 min. NC was more effective than CNT for carbon doping at the B site in MgB2 and, therefore, the NC-doped MgB2 samples had a lower critical temperature (T(c)) of 35.0-34.7 K than that of the CNT-doped samples (36.4-36.1 K). In addition, the J(c)(B) behavior was improved when NC and CNT were doped due to doping effect. Microstructural observation suggested that the nano-sized and unreacted NC particles and the nanodomain MgB2 acted as effective flux pinning centers for the NC- and CNT-doped MgB2, respectively.

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