Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
1.
BMC Ophthalmol ; 22(1): 293, 2022 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-35787271

RESUMEN

BACKGROUND: Capillary non-perfusion is an important characteristic for diabetic retinopathy (DR) indicating microvascular damage and ischemia. Data on the description and treatment outcomes of DR with large area of non-perfusion are lacking to date. We aim to describe the characteristics and treatment outcomes in a series of patients with DR who presented extensively large area of capillary non-perfusion (LACNP). METHODS: Fundus fluorescein angiograms from medical charts in patients diagnosed with DR between Jan 2017 and Dec 2019 were retrospectively reviewed. Clinical data in eyes with LACNP including imaging and laboratory findings at the first presentation were analyzed. The LACNP was defined as over 70% area of capillary non-perfusion throughout the whole image retina. The mean follow-up duration was 12.4 ± 16.7 months. Follow-up data including extensive pan-retinal photocoagulation and surgical intervention and treatment outcomes were evaluated. RESULTS: A total of 43 eyes in 24 patients with LACNP were included, accounting for 3.3% of DR populations in the same period. The overall percentage of non-perfusion area was 79.1 ± 8.1%. All patients received proper control of diabetes and hypertension, and extensive pan-retinal laser photocoagulation. During the follow-up periods, 20 eyes (46.5%) developed severe neovascular complications, of which 15 eyes (34.9%) underwent vitrectomy and/or anti-glaucoma surgeries. Conservative therapies including glycemic control and supplemental laser photocoagulation were conducted in 23 eyes (53.5%) without neovascular complications. In the final follow-up, best corrected visual acuity improved or maintained stable in 19 eyes (44.2%) while deteriorated in 24 eyes (55.8%). CONCLUSIONS: The presence of LACNP is the hallmark of advanced DR and often indicates a poor visual outcome, although aggressive treatments may slow DR progression and maintain central vision for some time.


Asunto(s)
Diabetes Mellitus , Retinopatía Diabética , Retinopatía Diabética/diagnóstico , Retinopatía Diabética/terapia , Humanos , Coagulación con Láser , Estudios Retrospectivos , Resultado del Tratamiento , Agudeza Visual
2.
Nanotechnology ; 32(2): 025205, 2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-32980827

RESUMEN

We propose a valley filter based on 8-Pmmn borophene which hosts two tilted Dirac cones. It is found that the application of a magnetic-electric barrier provided by a single ferromagnetic gate is sufficient to create valley-polarized current in 8-Pmmn borophene. The valley polarization of output current depends on the barrier orientation. Due to an intrinsic symmetry, it vanishes when the barrier orientation is along the tilted direction of Dirac cones. For the barrier orientation perpendicular to the tilted direction, the valley polarization for a realistic magnetic barrier can approach nearly 100% at proper Fermi energy and gate voltage. The remarkable valley contrast of conductance in this case is attributed to a new transmission resonance. The tilting of Dirac cones is essential for the predicted valley filtering. Our findings are helpful for valleytronic applications of two-dimensional materials with tilted Dirac cones.

3.
Sensors (Basel) ; 16(6)2016 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-27294935

RESUMEN

This paper presents a systematic pioneering study on the use of agricultural-purpose frequency domain reflectometry (FDR) sensors to monitor temperature and moisture of a subgrade in highway extension and reconstruction engineering. The principle of agricultural-purpose FDR sensors and the process for embedding this kind of sensors for subgrade engineering purposes are introduced. Based on field measured weather data, a numerical analysis model for temperature and moisture content in the subgrade's soil is built. Comparisons of the temperature and moisture data obtained from numerical simulation and FDR-based measurements are conducted. The results show that: (1) the embedding method and process, data acquisition, and remote transmission presented are reasonable; (2) the temperature and moisture changes are coordinated with the atmospheric environment and they are also in close agreement with numerical calculations; (3) the change laws of both are consistent at positions where the subgrade is compacted uniformly. These results suggest that the data measured by the agricultural-purpose FDR sensors are reliable. The findings of this paper enable a new and effective real-time monitoring method for a subgrade's temperature and moisture changes, and thus broaden the application of agricultural-purpose FDR sensors.

4.
J Sep Sci ; 37(6): 642-9, 2014 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-24415673

RESUMEN

In this study, a specific and sensitive LC-MS/MS method for the simultaneous analysis of type-B trichothecenes (deoxynivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol) and the de-epoxy metabolite of deoxynivalenol (de-epoxy-deoxynivalenol) in chicken muscle, liver, kidney, and fat tissues was developed and validated. The method involved an extraction step using ethyl acetate, followed by the evaporation of the supernatant, which was further purified by an Oasis HLB SPE cartridge (Waters, Milford, MA, USA). Chromatographic separation was performed on a C18 column by detection with MS in multiple-reaction monitoring mode and using a gradient elution program with 0.1% formic acid in water and methanol. The correlation coefficients (r) for each calibration curve were >0.99 within the experimental concentration range. The extraction recoveries ranged from 73.7 to 106.4%, with intraday and interday RSD < 11.6% at three levels of concentrations of 2, 10, and 100 µg/kg. The decision limits and the detection capabilities of the analytes in the chicken tissues ranged from 0.16 to 0.92 and 0.68 to 2.07 µg/kg, respectively. The results demonstrated the applicability of this sensitive procedure to the determination of trichothecenes in chicken tissue samples.


Asunto(s)
Tejido Adiposo/química , Riñón/química , Hígado/química , Músculos/química , Tricotecenos/análisis , Animales , Pollos , Cromatografía Líquida de Alta Presión , Espectrometría de Masas en Tándem , Tricotecenos/metabolismo
5.
J Diabetes Res ; 2024: 2550367, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39308630

RESUMEN

Aims: To investigate the impact of intravitreal injection of conbercept, a recombinant fusion protein with decoy receptors for the vascular endothelial growth factor (VEGF) family, on intraocular concentrations of angiogenic and inflammatory mediators in patients with proliferative diabetic retinopathy (PDR), analyzed its potential impact on surgical outcomes. Methods: Forty eyes from 40 patients with PDR were included in this prospective study. Patients received intravitreal injection of conbercept followed by vitrectomy or phacovitrectomy in 1 week. Aqueous humor samples were collected before and 1 week after the conbercept injection. The concentrations of angiogenic and inflammatory cytokines and chemokines were measured by flow cytometry. Follow-up clinical data were collected and analyzed. Results: Intravitreal conbercept injection significantly decreased aqueous concentrations of VEGF (325.5 (baseline) versus 22.3 pg/mL (postinjection), p < 0.0001), PlGF (39.5 versus 24.5 pg/mL, p < 0.0001), and PDGF-A (54.1 versus 47.0 pg/mL, p = 0.0016), while no impact on bFGF levels. For inflammatory mediators, the concentration of TNF-α (0.79 versus 0.45 pg/mL, p = 0.0004) and IL-8 (180.6 versus 86 pg/mL, p < 0.0001) were decreased, while IL-6 (184.1 versus 333.7 pg/mL, p = 0.0003) and IL-10 (1.1 versus 1.5 pg/mL, p = 0.0032) were increased. No significant changes in IFN-γ or MCP-1 were detected. Three months after surgery, the mean best-corrected visual acuity improved from a baseline of 1.8 ± 0.1 logMAR to 0.7 ± 0.1 logMAR (p < 0.0001), with 36 eyes (90%) achieving an improvement of visual function. Conclusions: Intravitreal conbercept injection presents dual effects of antiangiogenesis and anti-inflammation and can be served as an adjuvant treatment to vitrectomy for PDR patients.


Asunto(s)
Humor Acuoso , Citocinas , Retinopatía Diabética , Inyecciones Intravítreas , Proteínas Recombinantes de Fusión , Vitrectomía , Humanos , Retinopatía Diabética/tratamiento farmacológico , Masculino , Proteínas Recombinantes de Fusión/administración & dosificación , Proteínas Recombinantes de Fusión/uso terapéutico , Femenino , Persona de Mediana Edad , Citocinas/metabolismo , Estudios Prospectivos , Anciano , Humor Acuoso/metabolismo , Humor Acuoso/efectos de los fármacos , Adulto , Resultado del Tratamiento , Inhibidores de la Angiogénesis/administración & dosificación , Inhibidores de la Angiogénesis/uso terapéutico , Factor A de Crecimiento Endotelial Vascular/metabolismo
6.
Retina ; 33(6): 1258-62, 2013 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23508077

RESUMEN

PURPOSE: To investigate the structural features of outer retinal atrophy secondary to closed globe trauma and their correlation with visual prognosis, using spectral-domain optical coherence tomography (OCT). METHODS: In this retrospective study, patients with outer retinal atrophy secondary to closed globe trauma were examined with Topcon 3D OCT-1000. The foveal thickness was measured. The severity of outer retinal atrophy was graded into three levels: disruption of inner/outer segment layer, reduced thickness of outer nuclear layer, and disappearance of outer nuclear layer. Cases with >180 days of follow-up were included. The correlations between OCT features and best-corrected visual acuity at the last follow-up were analyzed. RESULTS: Overall, 52 eyes of 52 patients were included, with mean follow-up of 286 ± 200 days. Spectral-domain OCT revealed disruption of the inner/outer segment layer with atrophy of outer nuclear layer and disorganization of inner retina in severe cases. The final best-corrected visual acuity significantly correlated with foveal thickness (r = -0.813; P < 0.001) and the grade of outer retinal atrophy (r = 0.796; P < 0.001). CONCLUSION: Spectral-domain OCT revealed disruption of the inner/outer segment layer and atrophy of outer nuclear layer in cases of commotio retinae. Foveal thickness and grade of outer retinal atrophy were predictors for final visual outcome in these cases.


Asunto(s)
Lesiones Oculares/complicaciones , Retina/patología , Heridas no Penetrantes/complicaciones , Adolescente , Adulto , Atrofia/etiología , Atrofia/patología , Niño , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Pronóstico , Segmento Interno de las Células Fotorreceptoras Retinianas/patología , Segmento Externo de las Células Fotorreceptoras Retinianas/patología , Estudios Retrospectivos , Tomografía de Coherencia Óptica/métodos , Agudeza Visual/fisiología , Adulto Joven
7.
Nanomaterials (Basel) ; 12(21)2022 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-36364660

RESUMEN

Driven by the huge thermal energy in cement concrete pavements, thermoelectric (TE) cement has attracted considerable attention. However, the current TE cement shows poor performance, which greatly limits its application. Herein, a series of Bi0.5Sb1.5Te3/carbon nanotubes (CNTs) co-reinforced cement composites have been prepared, and their TE properties were systematically investigated. It was shown that the addition of Bi0.5Sb1.5Te3 particles can effectively improve the TE properties of CNTs-reinforced cement composites by building a better conductive network, increasing energy filtering and interfaces scattering. The Bi0.5Sb1.5Te3/CNTs cement composites with 0.6 vol.% of Bi0.5Sb1.5Te3 exhibits the highest ZT value of 1.2 × 10-2, increased by 842 times compared to that of the CNTs-reinforced cement composites without Bi0.5Sb1.5Te3. The power output of this sample with the size of 2.5 × 3.5 × 12 mm3 reaches 0.002 µW at a temperature difference of 19.1 K. These findings shed new light on the development of high-performance TE cement, which can guide continued advances in their potential application of harvesting thermal energy from pavements.

8.
Micromachines (Basel) ; 13(2)2022 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-35208357

RESUMEN

Transverse thermoelectric performance of the artificially tilted multilayer thermoelectric device (ATMTD) is very difficult to be optimized, due to the large degree freedom in device design. Herein, an ATMTD with Fe and Bi2Te2.7Se0.3 (BTS) materials was proposed and fabricated. Through high-throughput calculation of Fe/BTS ATMTD, a maximum of calculated transverse thermoelectric figure of merit of 0.15 was obtained at a thickness ratio of 0.49 and a tilted angle of 14°. For fabricated ATMTD, the whole Fe/BTS interface is closely connected with a slight interfacial reaction. The optimizing Fe/BTS ATMTD with 12 mm in length, 6 mm in width and 4 mm in height has a maximum output power of 3.87 mW under a temperature difference of 39.6 K. Moreover the related power density per heat-transfer area reaches 53.75 W·m-2. This work demonstrates the performance of Fe/BTS ATMTD, allowing a better understanding of the potential in micro-scaled devices.

9.
Ann Transl Med ; 9(6): 497, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33850894

RESUMEN

BACKGROUND: Due to the variety of clinical presentation, some tumors may be concealed and easily misdiagnosed, leading to delays in management. We report a series of patients who initially presented to an Ophthalmic Clinic with ocular symptoms and were subsequently diagnosed with extraocular tumors. METHODS: Patients who presented to the ophthalmic outpatient clinic at the Joint Shantou International Eye Center with ocular symptoms between April 2013 and December 2019 and were subsequently diagnosed with intracranial or systemic tumors were reviewed retrospectively. Clinical data, including ocular symptoms and signs, ophthalmic and systemic imaging examinations, and the results of tumor biopsies were collected and analyzed. RESULTS: Twenty-three patients were included in this study, of which 16 were female (69.6%) and 7 were male (30.4%). Chief complaints at the first visit included visual loss (n=20), proptosis (n=2), and diplopia (n=1). Ocular examination revealed disc pallor (n=8) and swelling (n=3), choroidal mass with or without chorioretinal detachment (n=5), and proptosis (n=2). Visual field (VF) examination was performed in 11 patients of which hemianopia (n=4) and non-specific field loss (n=7) were noted. Brain CT or MRI, together with histopathological findings from surgical biopsies confirmed the diagnosis of the intracranial tumors in 18 cases, including pituitary adenoma (n=7), meningioma (n=2), oligodendroglioma (n=1), sellar tumor (n=1), suprachiasmatic arteriovenous aneurysm (n=1), orbital glioma (n=1), multiple intracranial tumors (n=1), and sphenoid ossifying fibroma (n=1). Nasopharyngeal carcinoma (NPC) (n=3) was diagnosed with brain MRI and nasal endoscopy. Five patients were confirmed as choroidal metastasis secondary to lung cancer (n=3), hepatoma (n=1), and breast cancer (n=1). CONCLUSIONS: Patients with extraocular tumors may present initially to an ophthalmologist with ocular symptoms. It is important to identify and appropriately manage these patients to avoid unnecessary delays in future treatment.

10.
Asia Pac J Ophthalmol (Phila) ; 10(6): 564-571, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34608067

RESUMEN

PURPOSE: To evaluate the efficacy and safety of adequate silicone oil (SO) tamponade procedure in patients with complicated retinal detachment. METHODS: Thirty-one eyes in 31 patients were enrolled in this prospective case series. Adequate SO tamponade was performed by injecting the SO into the vitreous cavity and the entire anterior chamber, followed by posterior capsulotomy and inferior peripheral iridotomy. Preoperative and follow-up data including retinal anatomic reattachment and SO status, best-corrected visual acuity, intraocular pressure, surgical complications and management were collected and analyzed. RESULTS: Twenty-nine eyes presented with complete retinal reattachment after subsequent SO removal with a primary success rate of 93.5%. Seventeen patients (54.8%) had complete anterior chamber SO migration to the vitreous cavity within the first postoperative day. The average time for anterior chamber SO migration was 2.3 ±â€Š1.8 days. No oil-fluid interface in the vitreous cavity was observed in all the eyes, indicating a relatively adequate SO tamponade. Acute intraocular pressure elevation occurred in 16 (51.6%) eyes and was controllable under medication (n = 16) and anterior chamber paracentesis (n = 1). Two patients developed recurrent retinal detachment and received SO removal and a secondary adequate SO tamponade. At final follow-up, all the eyes had SO removal for at least 3 months and retinas maintained completely attached. CONCLUSIONS: The adequate SO tamponade procedure offers a simple, safe, and efficacious treatment alternative for complicated retinal detachment.


Asunto(s)
Desprendimiento de Retina , Aceites de Silicona , Humanos , Recurrencia Local de Neoplasia , Desprendimiento de Retina/cirugía , Resultado del Tratamiento , Agudeza Visual , Vitrectomía
11.
Materials (Basel) ; 13(23)2020 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-33261224

RESUMEN

The authors wish to make the following correction to this paper [...].

12.
J Neurol Sci ; 413: 116805, 2020 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-32259708

RESUMEN

Separated ventral and dorsal streams in auditory system have been proposed to process sound identification and localization respectively. Despite the popularity of the dual-pathway model, it remains controversial how much independence two neural pathways enjoy and whether visual experiences can influence the distinct cortical organizational scheme. In this study, representational similarity analysis (RSA) was used to explore the functional roles of distinct cortical regions that lay within either the ventral or dorsal auditory streams of sighted and early blind (EB) participants. We found functionally segregated auditory networks in both sighted and EB groups where anterior superior temporal gyrus (aSTG) and inferior frontal junction (IFJ) were more related to the sound identification, while posterior superior temporal gyrus (pSTG) and inferior parietal lobe (IPL) preferred the sound localization. The findings indicated visual experiences may not have an influence on this functional dissociation and the cortex of the human brain may be organized as task-specific and modality-independent strategies. Meanwhile, partial overlap of spatial and non-spatial auditory information processing was observed, illustrating the existence of interaction between the two auditory streams. Furthermore, we investigated the effect of visual experiences on the neural bases of auditory perception and observed the cortical reorganization in EB participants in whom middle occipital gyrus was recruited to process auditory information. Our findings examined the distinct cortical networks that abstractly encoded sound identification and localization, and confirmed the existence of interaction from the multivariate perspective. Furthermore, the results suggested visual experience might not impact the functional specialization of auditory regions.


Asunto(s)
Percepción Auditiva , Lóbulo Occipital , Estimulación Acústica , Ceguera , Mapeo Encefálico , Humanos , Imagen por Resonancia Magnética , Lóbulo Parietal , Lóbulo Temporal
13.
J Int Med Res ; 48(5): 300060520925705, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32436475

RESUMEN

OBJECTIVE: Some patients have been found to develop intraoperative amaurosis under sub-Tenon's anesthesia. We explored whether these patients have poor surgical outcomes during mid- to long-term postoperative follow-up. METHODS: In this case series, 74 of 85 patients with macular diseases who underwent phacoemulsification combined with vitrectomy under sub-Tenon's anesthesia developed intraoperative amaurosis. The surgical outcomes at the 2- and 4-month follow-ups in these patients were investigated and compared with the outcomes in patients without amaurosis using best-corrected visual acuity (BCVA), optical coherence tomography (OCT), and pattern visual evoked potential (PVEP). RESULTS: Both BCVA and the OCT-based macular structure in patients with intraoperative amaurosis showed significant postoperative improvement comparable with that of patients without amaurosis. The presence of intraoperative amaurosis was not associated with either macular hole closure or macular edema regression. PVEP revealed no significant changes in the wave latency or amplitude before and after surgery. CONCLUSION: Intraoperative amaurosis following sub-Tenon's block is commonly seen but does not predict a poor surgical prognosis. When a patient develops amaurosis during surgery, the surgeon should increase patient comfort through verbal communication rather than perform an additional intervention to help relieve the patient's anxiety.


Asunto(s)
Anestesia Local/efectos adversos , Ceguera/epidemiología , Complicaciones Intraoperatorias/epidemiología , Bloqueo Nervioso/efectos adversos , Facoemulsificación/efectos adversos , Vitrectomía/efectos adversos , Anestesia Local/métodos , Ceguera/etiología , Ceguera/psicología , Ceguera/rehabilitación , Potenciales Evocados Visuales , Estudios de Seguimiento , Fóvea Central/diagnóstico por imagen , Fóvea Central/cirugía , Humanos , Incidencia , Complicaciones Intraoperatorias/etiología , Complicaciones Intraoperatorias/psicología , Complicaciones Intraoperatorias/rehabilitación , Bloqueo Nervioso/métodos , Facoemulsificación/métodos , Periodo Posoperatorio , Factores Protectores , Perforaciones de la Retina/cirugía , Cápsula de Tenon/inervación , Tomografía de Coherencia Óptica , Resultado del Tratamiento , Vitrectomía/métodos
14.
Childs Nerv Syst ; 25(1): 13-20, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-18818933

RESUMEN

INTRODUCTION: MicroRNAs (miRNAs) are small (approximately 22 nucleotides) regulatory RNAs which play fundamental roles in many human diseases, including cancer. There is no report on the miRNA expression profile of retinoblastoma. METHODS: This work was undertaken to identify differentially expressed miRNAs in human retinoblastoma tissues by microRNA microarray technique, and some miRNAs were verified using northern blot analysis and the in situ hybridization method. RESULTS: A cluster of microRNAs was identified as highly expressed in retinoblastoma, including hsa-miR-494, hsa-let-7e, hsa-miR-513-1, hsa-miR-513-2, hsa-miR-518c*, hsa-miR-129-1, hsa-miR-129-2, hsa-miR-198, hsa-miR-492, hsa-miR-498, hsa-miR-320, hsa-miR-503, and hsa-miR-373*. CONCLUSION: These miRNAs are the first to be reported for human retinoblastoma and may play significant roles in regulating tumor genesis.


Asunto(s)
Perfilación de la Expresión Génica/métodos , MicroARNs/genética , Análisis de Secuencia por Matrices de Oligonucleótidos/métodos , Retinoblastoma/genética , Adulto , Northern Blotting , Análisis por Conglomerados , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Hibridación in Situ , Masculino
15.
JAMA Otolaryngol Head Neck Surg ; 150(9): 829-830, 2024 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-39052279

RESUMEN

A 32-year-old female patient presented with chronic discharging sinus with recurrent infection at the left sternoclavicular joint. What is your diagnosis?


Asunto(s)
Articulación Esternoclavicular , Humanos , Articulación Esternoclavicular/diagnóstico por imagen , Articulación Esternoclavicular/anomalías , Masculino , Femenino , Tomografía Computarizada por Rayos X
16.
Materials (Basel) ; 12(6)2019 Mar 17.
Artículo en Inglés | MEDLINE | ID: mdl-30884893

RESUMEN

Although the rutting resistance, fatigue cracking, and the resistance to water and frost are important for the asphalt pavement, the strength of asphalt mixture is also an important factor for the asphalt mixture design. The strength of asphalt mixture is directly associated with the overall performance of asphalt mixture. As a top layer material of asphalt pavement, the strength of asphalt mixture plays an indispensable role in the top structural bearing layer. In the present design system, the strength of asphalt pavement is usually achieved via the laboratory tests. The stress states are usually different for the different laboratory approaches. Even at the same stress level, the laboratory strengths of asphalt mixture obtained are significantly different, which leads to misunderstanding of the asphalt mixtures used in asphalt pavement structure design. The arbitrariness of strength determinations affects the effectiveness of the asphalt pavement structure design in civil engineering. Therefore, in order to overcome the design deviation caused by the randomness of the laboratory strength of asphalt mixtures, in this study, the direct tension, indirect tension, and unconfined compression tests were implemented on the specimens under different loading rates. The strength model of asphalt mixture under different loading modes was established. The relationship between the strength ratio and loading rate of direct tension, indirect tension, and unconfined compression tests was adopted separately. Then, one unified strength model of asphalt mixture with different loading modes was established. The preliminary results show that the proposed unified strength model could be applied to improve the accurate degree of laboratory strength. The effectiveness of laboratory-based asphalt pavement structure design can therefore be promoted.

17.
Materials (Basel) ; 12(12)2019 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-31200547

RESUMEN

TiO2 pillared montmorillonite (T/M) modifiers have been studied to alleviate the aging of asphalt pavement and degrade automobile exhaust, but the photocatalytic activity of ordinary TiO2 is not good enough. In this study, in order to improve the photocatalytic performance of T/M, different metal (Ce, Cu, Fe) doped modifiers were prepared based on T/M. Metal doped TiO2 pillared montmorillonite was prepared by the sol-gel method. The modifier was characterized by X-ray diffraction (XRD) and an Ultraviolet visible (UV-Vis) spectrophotometer. The results show that TiO2 with different metal ions successfully entered into the layer of organic montmorillonite (OMMT) to form a pillared structure. Compared with the undoped TiO2 pillared montmorillonite (T/M), the optical absorption edge of the metal doped TiO2 pillared montmorillonite has an obvious red shift. In addition, the influences of the different content of modifiers on the properties of the original bitumen and catalytic capacities for automobile exhaust were also investigated. The results show that Ce doped TiO2 (Ce-T/M) pillared montmorillonite has the best improvement in high temperature performance and ultraviolet (UV) resistance of bitumen. In the experiment of automobile exhaust degradation, the degradation law of NO and HC showed Cu-T/M > Ce-T/M > Fe-T/M > T/M. These three kinds of metal ions can effectively improve the photocatalytic degradation efficiency of T/M.

18.
Materials (Basel) ; 12(14)2019 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-31336712

RESUMEN

In order to describe the fatigue damage state of asphalt mixture more reasonably, direct tensile tests of the fatigue and the residual strength under stress levels of 1.00 MPa, 0.50 MPa and 0.25 MPa with five parallel tests were carried out. The trabecular specimens of AC-13C asphalt mixture (25 cm × 5 cm × 5 cm) were manufactured with Styrene-Butadiene-Styrene (SBS) modified asphalt, aggregate basalt and limestone mineral filler. The optimum asphalt-aggregate ratio was 5.2%. The dynamic modulus decay and the residual strength decay were termed as the damage variables to evaluate the fatigue damage process of asphalt mixtures, respectively. Based on the test results, the decay patterns of the dynamic modulus and the residual strength during fatigue tests under different stress states were revealed, and the model and the parameters of fatigue damage according to the corresponding decay patterns were obtained. Then, based on the assumption that the residual strength and dynamic modulus depend on the same damage state, the relationship between the two damage definitions was given, and the residual strength-dynamic modulus coupled model was established. The results showed that the residual strength-dynamic modulus coupled model could better describe the fatigue damage evolution law of asphalt mixture, and the parameter of this coupled model could be obtained by less residual strength tests. A modified formula for calculating the damage variables associated with residual strength and dynamic modulus was proposed based on the relationship between two kinds of damage variables.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA