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1.
Small ; : e2401812, 2024 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-38816772

RESUMEN

Carbon quantum dots (C-dots) have emerged as efficient fluorescent materials for solid-state lighting devices. However, it is still a challenge to obtain highly bright solid-state C-dots because of the aggregation caused quenching. Compared to the encapsulation of as-prepared C-dots in matrices, one-step preparation of C-dots/matrix complex is a good method to obtain highly bright solid-state C-dots, which is still quite limited. Here, an efficient and controllable vacuum-boosting gradient heating approach is demonstrated for in situ synthesis of a stable and efficient C-dots/matrix complex. The addition of boric acid strongly bonded with urea, promoting the selectivity of the reaction between citric acid and urea. Benefiting from the high reaction selectivity and spatial-confinement growth of C-dots in porous matrices, in situ synthesize C-dots bonded can synthesized dominantly with a crosslinked octa-cyclic compound, biuret and cyanuric acid (triuret). The obtained C-dots/matrix complex exhibited bright green emission with a quantum yield as high as 90% and excellent thermal and photo stability. As a proof-of-concept, the as-prepared C-dots are used for the fabrication of white light-emitting diodes (LEDs) with a color rendering index of 84 and luminous efficiency of 88.14 lm W-1, showing great potential for applications in LEDs.

2.
Small ; 20(16): e2306453, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38032174

RESUMEN

Colloidal quantum dots (QDs) are shown to be effective as light-harvesting sensitizers of metal oxide semiconductor (MOS) photoelectrodes for photoelectrochemical (PEC) hydrogen (H2) generation. The CdSe/CdS core/shell architecture is widely studied due to their tunable absorption range and band alignment via engineering the size of each composition, leading to efficient carrier separation/transfer with proper core/shell band types. However, until now the effect of core size on the PEC performance along with tailoring the core/shell band alignment is not well understood. Here, by regulating four types of CdSe/CdS core/shell QDs with different core sizes (diameter of 2.8, 3.1, 3.5, and 4.8 nm) while the thickness of CdS shell remains the same (thickness of 2.0 ± 0.1 nm), the Type II, Quasi-Type II, and Type I core/shell architecture are successfully formed. Among these, the optimized CdSe/CdS/TiO2 photoelectrode with core size of 3.5 nm can achieve the saturated photocurrent density (Jph) of 17.4 mA cm-2 under standard one sun irradiation. When such cores are further optimized by capping alloyed shells, the Jph can reach values of 22 mA cm2 which is among the best-performed electrodes based on colloidal QDs.

3.
Small ; 19(35): e2302056, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37186343

RESUMEN

The development of high-efficiency non-precious metal electrocatalysts for alkaline electrolyte hydrogen evolution reactions (HER) is of great significance in energy conversion to overcome the limited supply of fossil fuels and carbon emission. Here, a highly active electrocatalyst is presented for hydrogen production, consisting of 2D CoSe2 /Co3 S4 heterostructured nanosheets along Co3 O4 nanofibers. The different reaction rate between the ion exchange reaction and redox reaction leads to the heterogeneous volume swelling, promoting the growth of 2D structure. The 2D/1D heteronanostructures enable the improved the electrochemical active area, the number of active sites, and more favorable H binding energy compared to individual cobalt chalcogenides. The roles of the different composition of the heterojunction are investigated, and the electrocatalysts based on the CoSe2 /Co3 S4 @Co3 O4 exhibited an overpotential as low as 165 mV for 10 mA cm-2 and 393 mV for 200 mA cm-2 in 1 m KOH electrolyte. The as-prepared electrocatalysts remained active after 55 h operation without any significant decrease, indicating the excellent long-term operation stability of the electrode. The Faradaic efficiency of hydrogen production is close to 100% at different voltages. This work provides a new design strategy toward Co-based catalysts for efficient alkaline HER.

4.
Small ; 19(15): e2206316, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36642852

RESUMEN

Manipulating the separation and transfer behaviors of charges has long been pursued for promoting the photoelectrochemical (PEC) hydrogen generation based on II-VI quantum dot (QDs), but remains challenging due to the lack of effective strategies. Herein, a facile strategy is reported to regulate the recombination and transfer of interfacial charges through tuning the surface stoichiometry of heterostructured QDs. Using this method, it is demonstrated that the PEC cells based on CdSe-(Sex S1- x )4 -(CdS)2 core/shell QDs with a proper Ssurface /Cdsurface ratio exhibits a remarkably improved photocurrent density (≈18.4 mA cm-2 under one sun illumination), superior to the PEC cells based on QDs with Cd-rich or excessive S-rich surface. In-depth electrochemical and spectroscopic characterizations reveal the critical role (hole traps) of surface S atoms in suppressing the recombination of photogenerated charges, and further attribute the inferior performance of excessive S-rich QDs to the impeded charge transfer from QDs to TiO2 and electrolyte. This work puts forward a simple surface engineering strategy for improving the performance of QDs PEC cells, providing an efficient method to guide the surface design of QDs for their applications in other optoelectronic devices.

5.
Langmuir ; 39(20): 7184-7191, 2023 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-37167539

RESUMEN

Benefiting from the wide-range absorption and adjustable energy gap, carbon dots (C-dots) have attracted a great deal of attention and they have been used to sensitize semiconductor nanocomposites to boost the efficiency of energy conversion devices, while there is still a lack of fundamental understanding of the interaction between such materials and their influence on the catalytic activity on the reaction process. In this study, C-dots were used to modify TiO2 to form a direct Z-scheme (DZS) junction for enhancement of the photocatalytic activity. The C-dot/TiO2 composite was prepared by ultrasonication at room temperature through coupling between the Ti-O-C bond and electrostatic interaction. The C-dots can dramatically enhance the absorption of the composite by forming the DZS, and the composite is enabled to generate more free radicals, which facilitate ∼10 times higher photocatalytic activity compared to that of TiO2. As a proof of concept, the as-prepared C-dot/TiO2 was used for textile wastewater dye degradation. This study provides an efficient approach for room-temperature preparation of C-dot/TiO2 composites with high photocatalytic activity.

6.
Ann Plast Surg ; 2023 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-38170987

RESUMEN

OBJECTIVE: The present study aimed to evaluate the effectiveness of minimally invasive 980 nm laser-assisted lipolysis and skin tightening in lower eyelid blepharoplasty of Asian patients. METHODS: Patients with mild and moderate degree of eyebags underwent 980 nm laser-assisted lipolysis via lower eyelid stab incision between December 2017 and December 2019. Evaluation criteria was reviewed by photographs taken preoperatively and 6 months postoperatively in accordance with guidelines of Global Aesthetic Improvement Scale, the patient's perspective from the questionnaire with the perception of reduction in eyebags size, the average perception of improvement in skin tightening, and the patient overall satisfaction, all with a score of 1 to 5 (5 being the most noticeable and very satisfied) and complications such as dyspigmentation, hematoma, prolonged edema, skin bump and thermal burn were documented as well. RESULTS: A total of 178 cases with 137 women and 41 men (age range from 23 to 50 years) were included. Total energy of 1200 J to 2000 J was delivered to both eyebags at 6 to 10 W. They were followed up for at least 6 months. A total of 166 patients (93.26%) revealed an improvement in Global Aesthetic Improvement Scale, with the 12 patients (6.74%) complaint no change 6 month postoperatively. Perception of improvement in eye bag protrusion scored 4.39 ± 0.59, improvement in skin tightening scored 4.42 ± 0.58 and the overall patient's satisfaction scored 4.59 ± 0.53. The patients' average recovered swelling from 4.35 ± 2.3 days. There were 5 patients (2.8%) with dyspigmentation, 3 patients (1.69%) with prolonged edema and 2 patients (1.12%) with skin bump and none of the patients had thermal burn. All of them resolve after 6 months of follow up. CONCLUSION: Patients with mild to moderate degree of eyebags who resist surgery are good candidates for laser-assisted lower eyelid blepharoplasty.

7.
Aesthetic Plast Surg ; 47(5): 1806-1823, 2023 10.
Artículo en Inglés | MEDLINE | ID: mdl-37198297

RESUMEN

PURPOSE: Micro-focused ultrasound (MFU) is commonly used to improve facial relaxation and wrinkles. The objective of this study was to determine the efficacy of MFU for facial rejuvenation and patients' satisfaction with the treatment. METHOD: Articles published before December 2022 were retrieved using PubMed, Embase, Web of Science, and Cochrane Library databases. The retrieved literature was screened according to strict criteria, and the risk of bias of each study was assessed. RESULT: A total of 13 MFU studies for facial rejuvenation and tightening were included, involving 477 participants. Efficacy was assessed using the Global Aesthetic Improvement Scale (GAIS), and meta-analysis showed an overall response rate of 0.77 (95%CI: 0.58, 0.96) at 90 days after intervention and 0.69 (95%CI: 0.51, 0.87) at 180 days. 0.78 (95%CI: 0.61, 0.95) and 0.71 (95%CI: 0.54, 0.87) patients were satisfied and very satisfied overall at 90 days and 180 days, respectively. The pain score was on a 10-point scale, and the overall score was 3.10 (95%CI: 2.71, 3.94). There were no instances during treatment where patients could not tolerate pain. Sensitivity analysis showed that the results were robust. CONCLUSION: In conclusion, MFU is an effective way to treat facial rejuvenation and tightening. More large-sample, multicenter and randomized studies are needed to determine the optimal treatment parameters in the future. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .


Asunto(s)
Satisfacción del Paciente , Envejecimiento de la Piel , Humanos , Rejuvenecimiento/fisiología , Resultado del Tratamiento , Cara/diagnóstico por imagen , Dolor , Estudios Multicéntricos como Asunto
8.
Arch Toxicol ; 96(11): 2913-2926, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-35962800

RESUMEN

With the widespread use of copper oxide nanoparticles (CuO-NPs), their potential toxicity to the environment and biological health has attracted close attention. Heterophil extracellular traps (HETs) are an innate immune mechanism of chicken heterophils against adverse stimuli, but excessive HETs cause damage. Here, we explored the effect and mechanism of CuO-NPs on HETs formation in vitro and further evaluated the potential role of HETs in chicken liver and kidney injury. Heterophils were exposed to 5, 10, and 20 µg/mL of CuO-NPs for 2 h. The results showed that CuO-NPs induced typical HETs formation, which was dependent on NADPH oxidase, P38 and extracellular regulated protein kinases (ERK1/2) pathways, and glycolysis. In in vivo experiments, fluorescence microplate and morphological analysis showed that CuO-NPs elevated the level of HETs in chicken serum and caused liver and kidney damage. Meanwhile, CuO-NPs caused hepatic oxidative stress (MDA, SOD, CAT, and GSH-PX imbalance), and also induced an increase in mRNA expression of their inflammatory and apoptosis-related factors (IL-1ß, IL-6, TNF-α, COX-2, iNOS, NLRP3, and Caspase-1, 3, 11). However, these results were significantly altered by DNase I (HETs degradation reagent). In conclusion, the present study demonstrates for the first time that CuO-NPs induce the formation of HETs and that HETs exacerbate pathological damage in chicken liver and kidney by promoting oxidative stress and inflammation, providing insights into immunotoxicity and potential prevention and treatment targets caused by CuO-NPs overexposure.


Asunto(s)
Trampas Extracelulares , Nanopartículas del Metal , Animales , Caspasas , Pollos , Cobre/toxicidad , Ciclooxigenasa 2 , Desoxirribonucleasa I/farmacología , Interleucina-6 , Hígado , Nanopartículas del Metal/toxicidad , NADPH Oxidasas/farmacología , Proteína con Dominio Pirina 3 de la Familia NLR , Estrés Oxidativo , Óxidos , Proteínas Quinasas , ARN Mensajero , Superóxido Dismutasa , Factor de Necrosis Tumoral alfa
9.
Biol Pharm Bull ; 44(6): 771-779, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33731543

RESUMEN

Emodin (1,3,8-trihydroxy-6-methylanthraquinone), as an active ingredient in rhubarb roots and rhizomes, has been reported to possess various pharmacological properties including anti-tumor effects. Recent studies have confirmed that emodin inhibited cell proliferation and induced apoptosis of cancer cells. However, the inhibitory effect of emodin on the migration and invasion of melanoma cells and its underlying mechanism are still unclear. In the study, we observed the impercipient effects of emodin in B16F10 and A375 melanoma cells with strong metastatic abilities, focusing on the functions and mechanisms of migration and invasion of B16F10 and A375 melanoma cells. Cell counting kit-8 (CCK-8), colony formation test and Annexin V-fluorescein isothiocyanate (FITC)/propidium iodide (PI) staining tests confirmed that emodin possessed anti-proliferative and pro-apoptotic activities in B16F10 and A375 cells. The inhibitory effects on the migration and invasion of B16F10 and A375 cells were proved by wound healing assay and Transwell methods. Moreover, immunofluorescence assay approved the decrease in protein expression of matrix metalloproteinas (MMP)-2/-9 by emodin, and Western blot analyses revealed that emodin could increase the Bax/Bcl-2 ratio and inhibit the MMP-2/-9 protein expression and Wnt/ß-catenin pathway in a dose-depended manner. BML-284, as an agonist of Wnt/ß-catenin signaling pathway, reversed the effects of emodin on cell growth, migration and invasion in B16F10 cells. These findings may suggest that emodin treatment can be a promising therapeutic strategy for melanoma with highly metastatic abilities.


Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Emodina/farmacología , Melanoma/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Rheum/química , Vía de Señalización Wnt , beta Catenina/metabolismo , Antineoplásicos Fitogénicos/uso terapéutico , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Emodina/uso terapéutico , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Genes myc , Humanos , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 9 de la Matriz/metabolismo , Melanoma/tratamiento farmacológico , Invasividad Neoplásica , Fitoterapia , Extractos Vegetales/farmacología , Extractos Vegetales/uso terapéutico , Inhibidores de Proteínas Quinasas/uso terapéutico , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Factores de Transcripción TCF/metabolismo , Proteína X Asociada a bcl-2/metabolismo
10.
Small ; 16(28): e2000804, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32468691

RESUMEN

Colloidal quantum dots (QDs) are a fascinating class of semiconducting nanocrystals, thanks to their optical properties tunable through size and composition, and simple synthesis methods. Recently, colloidal double-emission QDs have been successfully applied as competitive optical temperature sensors, since they exhibit structure-tunable double emission, temperature-dependent photoluminescence, high quantum yield, and excellent photostability. Until now, QDs have been used as nanothermometers for in vivo biological thermal imaging, and thermal mapping in complex environments at the sub-microscale to nanoscale range. In this Review, recent progress for QD-based nanothermometers is highlighted and perspectives for future work are described.

11.
Acc Chem Res ; 51(3): 609-618, 2018 03 20.
Artículo en Inglés | MEDLINE | ID: mdl-29260851

RESUMEN

Semiconductor nanocrystals exhibit size-tunable absorption and emission ranging from the ultraviolet (UV) to the near-infrared (NIR) spectral range, high absorption coefficient, and high photoluminescence quantum yield. Effective surface passivation of these so-called quantum dots (QDs) may be achieved by growing a shell of another semiconductor material. The resulting core/shell QDs can be considered as a model system to study and optimize structure/property relations. A special case consists in growing thick shells (1.5 up to few tens of nanometers) to produce "giant" QDs (g-QDs). Tailoring the chemical composition and structure of CdSe/CdS and PbS/CdS g-QDs is a promising approach to widen the spectral separation of absorption and emission spectra (i.e., the Stokes shift), improve the isolation of photogenerated carriers from surface defects and enhance charge carrier lifetime and mobility. However, most stable systems are limited by a thick CdS shell, which strongly absorbs radiation below 500 nm, covering the UV and part of the visible range. Modification of the interfacial region between the core and shell of g-QDs or tuning their doping with narrow band gap semiconductors are effective approaches to circumvent this challenge. In addition, the synthesis of g-QDs composed of environmentally friendly elements (e.g., CuInSe2/CuInS2) represents an alternative to extend their absorption into the NIR range. Additionally, the band gap and band alignment of g-QDs can be engineered by proper selection of the constituents according to their band edge positions and by tuning their stoichiometry during wet chemical synthesis. In most cases, the quasi-type II localization regime of electrons and holes is achieved. In this type of g-QDs, electrons can leak into the shell region, while the holes remain confined within the core region. This electron-hole spatial distribution is advantageous for optoelectronic devices, resulting in efficient electron-hole separation while maintaining good stability. This Account provides an overview of emerging engineering strategies that can be adopted to optimize structure/property relations in colloidal g-QDs for efficient photon management or charge separation/transfer. In particular, we focus on our recent contributions to this rapidly expanding field of research. We summarize the design and synthesis of a variety of colloidal g-QDs with the aim of tuning the optical properties, such as absorption/emission in a wide region of the solar spectrum, which allows enlargement of their Stokes shift. We also describe the band alignment within these systems, charge carrier dynamics, and charge transfer from g-QDs into semiconducting oxides. We show how these tailored g-QDs may be used as active components in luminescent solar concentrators, photoelectrochemical cells for hydrogen generation, QD-sensitized solar cells and optical nanothermometers. In each case, we aim at providing insights on structure/property relationships and on how to optimize them toward improving device performance. Finally, we describe perspectives for future work, sketching new directions and opportunities in this field of research at the intersection between chemistry, physics, materials science and engineering.

12.
Chem Soc Rev ; 47(15): 5866-5890, 2018 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-29915833

RESUMEN

Luminescent solar concentrators (LSCs) can serve as large-area sunlight collectors, are suitable for applications in high-efficiency and cost-effective photovoltaics (PVs), and provide adaptability to the needs of architects for building-integrated PVs, which makes them an attractive option for transforming buildings into transparent or non-transparent electricity generators. Compared with traditional organic dyes, colloidal semiconducting quantum dots (QDs) are excellent candidates as emitters for LSCs because they exhibit wide size/shape/composition-tunable absorption spectra ranging from ultraviolet to near infrared, significantly overlapping with the solar spectrum. They also feature narrow emission spectra, high photoluminescence quantum yields, high absorption coefficients, solution processability and good photostability. Most importantly, QDs can be engineered to provide a minimal overlap between absorption and emission spectra, which is key to the realization of large-area LSCs with largely suppressed reabsorption energy losses. In this review article, we will first present and discuss the working principle of LSCs, the synthesis of colloidal QDs using wet-chemistry approaches, the optical properties of QDs, their band alignment and the intrinsic relationship between the band energy structure and optical properties of QDs. We focus on emerging architectures, such as core/shell QDs. We then highlight recent progress in QD-based LSCs and their anticipated applications. We conclude this review article with the major challenges and perspectives of LSCs in future commercial technologies.

13.
Small ; 14(51): e1801668, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30294898

RESUMEN

Metal chalcogenide quantum dots (QDs) are among the most promising materials as light harvesters in all-inorganic systems for applications in solar cells and production of solar fuels. The electronic band structure of composite QDs formed by lead and cadmium chalcogenides directly grafted on highly oriented pyrolytic graphite surfaces through successive ionic layer absorption and reaction is investigated. Atomic force microscopy and Kelvin probe force microscopy (KPFM) are applied to investigate PbS, CdS, and PbS/CdS QD systems. The variation of the surface potential of individual QDs is measured, investigating the evolution of the electronic band structure as a function of QD size and composition. A shift of the Fermi level toward more negative values occurs when QD size is increased. The shift is more pronounced in CdS than in PbS, while the composite PbS/CdS exhibits an intermediate behavior. The calculated shift is in good agreement with the experiments. These results highlight the ability of KPFM to directly measure the electronic band structure in individual QDs of metal chalcogenide composites. This feature regulates charge dynamics in composite systems, thereby affecting device performance. This work provides valuable insights for applications in several fields, in which charge injection plays a major role.

14.
Lasers Med Sci ; 33(7): 1505-1511, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-29687409

RESUMEN

Day surgery is being more and more adopted by clinicians. Higher wavelength lasers give patients better experience than lower wavelength lasers, which makes it more suitable for day surgery. This study compares the short- and mid-term efficacy, postoperative morbidity, and patient satisfaction of "1470-nm endovenous laser ablation (EVLA) combining foam sclerotherapy in day surgery" with "810-nm EVLA with high ligation combining foam sclerotherapy in hospital surgery" on great saphenous vein (GSV) insufficiency postoperatively. A single-institution historical cohort study of 194 patients was performed in Shanghai Ninth People's Hospital, China. Ninety-seven patients received 1470-nm EVLA combining foam sclerotherapy in day surgery ("1470-nm group"), and 97 patients received 810-nm EVLA with high ligation combining foam sclerotherapy in hospital surgery recommended by guidelines ("810-nm group"). No significant difference was found between the 1470-nm group and the 810-nm group in terms of GSV occlusion rate (both 100%), complication rate, and recurrence rate (8.2 vs. 11.3%) during the period of 1-12 months after surgery. Serious complications in the 1470-nm group and 810-nm group were 0 and 1.0%. Minor complications in the 1470-nm group and 810-nm group were ecchymosis at 20.6 and 18.6%, edema at 69.1 and 63.9%, and paresthesia around ankle at 0 and 3.1%, respectively. Advantage of the 1470-nm group over the 810-nm group was statistically significant considering the patient perioperative comfort and economic cost. Treatment of 1470-nm EVLA combining foam sclerotherapy in day surgery has similar efficacy as the 810-nm EVLA with high ligation combining foam sclerotherapy in hospital surgery in GSV insufficiency and is more comfortable with less incision, hospitalization procedure, and medical costs. It may be a new option for patients who are afraid or unable to be hospitalized.


Asunto(s)
Terapia por Láser/métodos , Extremidad Inferior/patología , Extremidad Inferior/cirugía , Escleroterapia/métodos , Várices/cirugía , China , Estudios de Cohortes , Femenino , Humanos , Terapia por Láser/efectos adversos , Terapia por Láser/economía , Extremidad Inferior/efectos de la radiación , Masculino , Persona de Mediana Edad , Dolor Postoperatorio/etiología , Vena Safena/efectos de la radiación , Vena Safena/cirugía , Escleroterapia/efectos adversos , Escleroterapia/economía , Resultado del Tratamiento
15.
Small ; 12(29): 3888-907, 2016 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-27345736

RESUMEN

Lanthanide doped upconverting nanoparticles (UCNPs) have emerged as a new class of luminescent materials, with major discoveries and overall significant progress during the last decade. Unlike multiphoton absorption in organic dyes or semiconductor quantum dots, lanthanide doped UCNPs involve real intermediate quantum states and convert infrared (IR) into visible light via sequential electronic excitation. The relatively high efficiency of this process even at low radiation flux makes UCNPs particularly attractive for many current and emerging areas of technology. The aim of this article is to highlight several recent advances in this rapidly growing field, emphasizing the relationships between structure and properties of UCNPs. Additionally, various strategies developed for the synthesis of UCNPs with a focus on the various synthetic approaches that yield high-quality monodisperse samples with controlled size, shape and crystalline phase are reviewed. Emerging synthetic approaches towards designed structure to improve the optical and electronic properties of UCNPs are discussed. Finally, recent examples of applications of UCNPs in biomedical and optoelectronics research, giving our own perspectives on future directions and emerging possibilities of the field are described.

16.
Small ; 12(38): 5354-5365, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27515385

RESUMEN

Luminescent solar concentrators (LSCs) can potentially reduce the cost of solar cells by decreasing the photoactive area of the device and boosting the photoconversion efficiency (PCE). This study demonstrates the application of "giant" CdSe/Cdx Pb1-x S core/shell quantum dots (QDs) as light harvesters in high performance LSCs with over 1.15% PCE. Pb addition is critical to maximize PCE. First, this study synthesizes "giant" CdSe/Cdx Pb1-x S QDs with high quantum yield (40%), narrow size distribution (<10%), and stable photoluminescence in a wide temperature range (100-300 K). Subsequently these thick alloyed-shell QDs are embedded in a polymer matrix, resulting in a highly transparent composite with absorption spectrum covering the range 300-600 nm, and are applied as active material for prototype LSCs. The latter exhibits a 15% enhancement in efficiency with respect to 1% PCE of the pure-CdS-shelled QDs. This study attributes this increase to the contribution of Pb doping. The results demonstrate a straightforward approach to enhance light absorption in "giant" QDs by metal doping, indicating a promising route to broaden the absorption spectrum and increase the efficiency of LSCs.

17.
Nanotechnology ; 27(49): 495405, 2016 Dec 09.
Artículo en Inglés | MEDLINE | ID: mdl-27834311

RESUMEN

Quantum dots (QDs) are attractive systems for potential applications in future solar energy technologies, due to their optical properties which are tunable as a function of size and composition. In this study, we synthesized PbS QDs with first excitonic peak in the range 1060 to 1300 nm using a PbCl2/sulfur molar ratio of 10:1. The first excitonic absorption peak from 1300 to 950 nm of the PbS/CdS core/shell QDs can be further synthesized via the cation exchange approach. Our method resulted in high quantum yield, good stability, monodisperse QD solutions with a full surface coverage by excess Cd cations. In addition, we used our core/shell QDs in a photoelectrochemical cell for hydrogen generation. This heterostructure exhibited a saturated photocurrent as high as 3.3 mA cm-2, leading to ∼29 ml cm-2 d-1 hydrogen generation, indicating the strong potential of our core/shell QDs for applications in water splitting.

18.
Phys Chem Chem Phys ; 18(46): 31828-31835, 2016 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-27841403

RESUMEN

In this study, we report anomalous size-dependent photoluminescence (PL) intensity variation of PbS quantum dots (QDs) with the formation of a thin CdS shell via a microwave-assisted cation exchange approach. Thin shell formation has been established as an effective strategy for increasing the PL of QDs. Nonetheless, herein we observed an unusual PL decrease in ultrasmall QDs upon shell formation. We attempted to understand this abnormal phenomenon from the perspective of trap density variation and the probability of electrons and holes reaching surface defects. To this end, the quantum yield (QY) and PL lifetime (on the ns-µs time scales) of pristine PbS QDs and PbS/CdS core/shell QDs were measured and the radiative and non-radiative recombination rates were derived and compared. Moreover, transient absorption (TA) analysis (on the fs-ns time scale) was performed to better understand exciton dynamics at early times that lead to and affect longer time dynamics and optical properties such as PL. These experimental results, in conjunction with theoretical calculations of electron and hole wave functions, provide a complete picture of the photophysics governing the core/shell system. A model was proposed to explain the size-dependent optical and dynamic properties observed.

19.
Small ; 11(43): 5741-6, 2015 Nov 18.
Artículo en Inglés | MEDLINE | ID: mdl-26467511

RESUMEN

Core-shell quantum dots serve as self-calibrating, ultrasensitive, multiparametric, near-infrared, and biocompatible temperature sensors. They allow temperature measurement with nanometer accuracy in the range 150-373 K, the broadest ever recorded for a nanothermometer, with sensitivities among the highest ever reported, which makes them essentially unique in the panorama of biocompatible nanothermometers with potential for in vivo biological thermal imaging and/or thermoablative therapy.


Asunto(s)
Materiales Biocompatibles/síntesis química , Mediciones Luminiscentes/instrumentación , Puntos Cuánticos , Termografía/instrumentación , Transductores , Materiales Biocompatibles/normas , Calibración , Diseño de Equipo , Análisis de Falla de Equipo , Mediciones Luminiscentes/normas , Ensayo de Materiales , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Temperatura , Termografía/normas
20.
Biochem Biophys Res Commun ; 443(2): 598-603, 2014 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-24333432

RESUMEN

Hypoxia-inducible factor 1α (HIF1α) is a transcription factor involved in the growth, invasion and metastasis of malignant tumors. Glycogen synthase kinase 3 beta (GSK3ß) is a protein kinase involved in a variety of signaling pathways, such as the Wnt and NF-κB pathways; this kinase can affect tumor progress through the regulation of transcription factor expression and apoptosis. Recent studies showed that GSK3ß was involved in the expression of HIF1α. However, the effect of GSK3ß on HIF1α expression in osteosarcoma cells remains unknown. To understand the relationship between GSK3ß and HIF1α comprehensively, small RNA interference techniques, Western blot analyses, quantitative real-time PCR analyses and luciferase assays were used in our study. Experimental data revealed that inhibition of GSK3ß could increase HIF1α protein levels and expression of its target genes by increasing the stability of the HIF1α mRNA, not by affecting the HIF1α protein stability, and that this process could be mediated by nucleolin.


Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Osteosarcoma/metabolismo , Fosfoproteínas/metabolismo , Estabilidad del ARN/fisiología , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Línea Celular Tumoral , Regulación hacia Abajo , Humanos , ARN Mensajero/genética , Nucleolina
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