86,649 research outputs found
Ultrasensitive, Biocompatible, Self-Calibrating, Multiparametric Temperature Sensors
No full textCore-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
Tailoring the Heterostructure of Colloidal Quantum Dots for Ratiometric Optical Nanothermometry
No full textColloidal 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
Ultrasensitive, Biocompatible, Self-Calibrating, Multiparametric Temperature Sensors
No full textCore-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
Temperature Sensors: Ultrasensitive, Biocompatible, Self‐Calibrating, Multiparametric Temperature Sensors (Small 43/2015)
No full textPbS/CdS core/shell quantum dots are applied as ultrasensitive, biocompatible, self-calibrating, multi-parametric temperature sensors by H. Zhao, A. Vomiero, and F. Rosei. On page 5741, they show how part of the colour emission comes from the PbS core and part from the CdS shell. The relative intensity of these emissions is temperature-dependent, inducing color changes when the temperature varies. The lifetime and peak position of PbS emission also monotonically change with the temperature, offering a platform for a multi-parametric detection system.</p
Solar Concentrators : Absorption Enhancement in “Giant” Core/Alloyed-Shell Quantum Dots for Luminescent Solar Concentrator
No full textOn page 5354, H. G. Zhao, F. Rosei, A. Vomiero, and co-workers, demonstrate the application of “giant” core/shell quantum dots as light harvesters in high-performance luminescent solar concentrators (LSCs) with over 1.15% power conversion efficiency. Metal doping approach can tune the absorption spectra of QDs to better match the solar spectrum, and represents a significant advance for the development of high-efficiency LSCs for cost-effective photovoltaic applications.</p
ACCUMULATION OF TRIBUTYLTIN CHLORIDE BY CARP (CYPRINUS CARPIO L.).
No full textIn these last twenty-five years, tributyltin compounds (TBTs) have been widely used as successful system for the control of growth of fouling organisms on structures submerged in aquatic environment. The TBT compounds are highly toxic to aquatic organisms. The aim of the present work was to evaluate possible uptake of tributyltin chloride (TBTC) by carp (Cyprinus carpio L.) and the subsequent accumulation in organs and tissues. Two groups of 15 fishes of about 1 kg each were fed on wet pellets (3% of live weight) contaminated for one week by TBTC 25 mg/kg and 100 mg/kg, respectively. TBTC levels were measured by high resolution gas chromatography coupled with low resolution mass spectrometry. The concentrations were the highest in kidney and liver, whereas in the brain were less than one filth of renal values. On the other hand, low levels were found in the muscle tissue. However, we believe this represents a great risk for human health through dietary uptake, because TBTs are immunotoxic substances
Direct Measurement of Electronic Band Structure in Single Quantum Dots of Metal Chalcogenide Composites
No full textMetal 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
Colloidal thick-shell pyramidal quantum dots for efficient hydrogen production
No full textColloidal semiconductor quantum dots (QDs) have attracted a great attention for their potential applications in optoelectronic devices, such as water splitting, luminescent solar concentrators, and solar cells, because of their size/shape/composition-dependent optoelectronic properties. However, the fast electron-hole (e-h) recombination and slow charge separation of QDs limit their applications as light absorbers in high-efficiency optoelectronic devices. Here, we synthesized thick-shell CdSe/CdSexS1-x/CdS QDs with pyramidal shape, which exhibit a quantum yield of ~ 15%, with a long radiative lifetime up to ~ 100 ns due to the spatial separation of the e/h wavefunction and significantly broadened light absorption toward the 500–700 nm range, compared to CdSe/CdS unalloyed QDs. As a proof-of-concept, the pyramidal QDs are applied as light absorbers in a photoelectrochemical (PEC) system, leading to a saturated photocurrent density of ~ 12 mA/cm2 (with a H2 generation rate of 90 mL cm−2 day−1), which is a record for thick-shell QD-based photoelectrodes in PEC hydrogen generation. Core/thick-shell QDs hold great potential for breakthrough developments in the field of QD-based optoelectronic devices
Adaptive nanolaminate coating by atomic layer deposition
No full textAtomic layer deposition (ALD) was used to deposit ZnO/Al2O3/V2O5 nanolaminate coatings to demonstrate a coating system with temperature adaptive frictional behaviour. The nanolaminate coating exhibited excellent conformity and crack-free coating of thickness 110 nm over Inconel 718 substrate. The ALD trilayer coating showed a hardness and elastic modulus of 12 GPa and 193 GPa, respectively. High-temperature tribology of the nanolaminate trilayer was tested against steel ball in dry sliding condition at 25 °C (room temperature, RT), 200 °C, 300 °C, and 400 °C. It was found that the nanolaminate coating showed a low coefficient of friction (COF) and wear rate at RT and 300 °C. The trilayer coating was found intact and stable at all temperatures during the friction tests. The adaptability of nanolaminate coating with the temperature was verified by performing the cyclic friction test at 300 °C and RT. The low COF and wear rate had been attributed to the (100) and (002) basal plane sliding of ZnO top layer, and the interlayer sliding of weakly bonded planes parallel to (001) plane in V2O5 bottom layer. Furthermore, even after the removal of ZnO coating during the tribotest, the bottom V2O5 layer coating stabilized the COF and wear rate at RT and 300 °C
Quantum Dots: Near‐Infrared Colloidal Quantum Dots for Efficient and Durable Photoelectrochemical Solar‐Driven Hydrogen Production (Adv. Sci. 3/2016)
No full textIn article number 1500345, G. Zhao, A. Vomiero, F. Rosei, and co-workers develop a new hybrid photoelectrochemical photoanode to generate H2 from water, composed of a TiO2 mesoporous frame functionalized by colloidal core@shell quantum dots (QDs) followed by CdS and ZnS capping layers. Saturated photocurrent density as high as 11.2 mA cm−2 is obtained in a solar-cell-driven PEC system using near infrared QDs.Godkänd; 2016; 20160314 (andbra);Full text license: CC BY-NC</p
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