Localized three-photon upconversion enhancement in silver nanowire networks and its effect in thermal sensing.

The quest for enhancing the upconversion luminescence (UCL) efficiency of rare-earth doped materials has been a common target in nanophotonics research. Plasmonic nanoarchitectures have proven potential for amplifying UCL signals, prompting investigations into localized enhancement effects within noble metal nanostructures. In this work we investigate the localized enhancement of UCL in silver nanowire (AgNW) networks coated with upconversion nanoparticles (UCNPs) by employing hyperspectral microscopy to unveil distinctive regions of local enhancement.

Optical Printing of Single Au Nanostars.

Obtaining arrays of single nanoparticles with three-dimensional complex shapes is still an open challenge. Current nanolithography methods do not allow for the preparation of nanoparticles with complex features like nanostars. In this work, we investigate the optical printing of gold nanostars of different sizes as a function of laser wavelength and power.

Synthesis, characterization, and incorporation of upconverting nanoparticles into a dental adhesive.

The purpose of this study was to describe the synthesis, characterization, and functionalization of b-NaYF4:30%Yb/0.5%Tm upconverting nanocrystals for use as nanofillers in a dental adhesive and microscopically evaluate the interface between the particles and a commercial adhesive. The upconverting nanoparticles were synthesized and purified by thermal decomposition, and their chemical composition determined by energy dispersive X-Ray spectroscopy.

Controlling the thermal switching in upconverting nanoparticles through surface chemistry.

Photon upconversion taking place in small rare-earth-doped nanoparticles has been recently observed to be thermally modulated in an anomalous manner, showing thermal enhancement of the emission intensity. This effect was proved to be linked to the role of adsorbed water molecules as surface quenchers. The surface capping of the particles has a direct influence on the thermal dynamics of water adsorption and desorption, and therefore on the optical properties.

Thermal enhancement of upconversion emission in nanocrystals: a comprehensive summary.

Luminescence thermal stability is a major figure of merit of lanthanide-doped nanoparticles playing an essential role in determining their potential applications in advanced optics. Unfortunately, considering the intensification of multiple electron-vibration interactions as temperature increases, luminescence thermal quenching of lanthanide-doped materials is generally considered to be inevitable. Recently, the emergence of thermally enhanced upconversion luminescence in lanthanide-doped nanoparticles seemed to challenge this stereotype, and the research on this topic rapidly aroused wide attention.

Self-Calibrated Double Luminescent Thermometers Through Upconverting Nanoparticles.

Luminescent nanothermometry uses the light emission from nanostructures for temperature measuring. Non-contact temperature readout opens new possibilities of tracking thermal flows at the sub-micrometer spatial scale, that are altering our understanding of heat-transfer phenomena occurring at living cells, micro electromagnetic machines or integrated electronic circuits, bringing also challenges of calibrating the luminescent nanoparticles for covering diverse temperature ranges. In this work, we report self-calibrated double luminescent thermometers, embedding in a poly(methyl methacrylate) film Er- and Tm-doped upconverting nanoparticles.

Thermoplasmonic enhancement of upconversion in small-size doped NaGd(Y)F nanoparticles coupled to gold nanostars.

Plasmon enhancement of luminescence is a common strategy to boost the efficiency of both fluorescence and upconversion via the augmented local electromagnetic field. However, the local heating produced when exciting the plasmon resonance of metallic nanoparticles is often overlooked. As higher temperatures are usually detrimental for radiative processes, only the electromagnetic contribution is exploited for enhancement.

Tethering Luminescent Thermometry and Plasmonics: Light Manipulation to Assess Real-Time Thermal Flow in Nanoarchitectures.

The past decade has seen significant progresses in the ability to fabricate new mesoporous thin films with highly controlled pore systems and emerging applications in sensing, electrical and thermal isolation, microfluidics, solar cells engineering, energy storage, and catalysis. Heat management at the micro- and nanoscale is a key issue in most of these applications, requiring a complete thermal characterization of the films that is commonly performed using electrical methods. Here, plasmonic-induced heating (through Au NPs) is combined with Tb/Eu luminescence thermometry to measure the thermal conductivity of silica and titania mesoporous nanolayers.

Magnetic Gold Confined in Ordered Mesoporous Titania Thin Films: A Noble Approach for Magnetic Devices.

In the past decade, the surprising magnetic behavior of gold nanoparticles has been reported. This unexpected property is mainly attributed both to size and surface effects. Mesoporous thin films are ideal matrices for metallic nanoparticles inclusion, because of their highly accessible and tailorable pore systems that lead to completely tunable chemical environments.

Silver nanoparticle-mesoporous oxide nanocomposite thin films: a platform for spatially homogeneous SERS-active substrates with enhanced stability.

We introduce a nanoparticle-mesoporous oxide thin film composite (NP-MOTF) as low-cost and straightforward sensing platforms for surface-enhanced Raman Spectroscopy (SERS). Titania, zirconia, and silica mesoporous matrices templated with Pluronics F-127 were synthesized via evaporation-induced self-assembly and loaded with homogeneously dispersed Ag nanoparticles by soft reduction or photoreduction. Both methods give rise to uniform and reproducible Raman signals using 4-mercaptopyridine as a probe molecule.

Electrical conductivity in patterned silver-mesoporous titania nanocomposite thin films: towards robust 3D nano-electrodes.

The space-resolved electrical conductivity of patterned silver nanoparticle (NP) arrays embedded in mesoporous TiO(2) thin films was locally evaluated using a conductive-tip AFM. A remarkable conductivity dependence on the film mesostructure and metal NP loading was observed, confirming a three-dimensional current flow throughout the nanocomposite.

Patterned production of silver-mesoporous titania nanocomposite thin films using lithography-assisted metal reduction.

A simple method that allows selective positioning of nanoparticles into mesoporous monolayer or multilayer thin films is presented. This technique applies UV lithography in order to bring about in situ light-induced reduction of silver in templated cavities of TiO2. The nanoparticle lithography presented here provides a novel approach to hierarchical lithography patterning for multifunctional devices.

Extrauterine life duration and ontogenic EEG parameters in preterm newborns with and without major ultrasound brain lesions.

Objective: To determine whether extrauterine life duration is associated with different ontogenic electroencephalographic (EEG) patterns in premature infants compared with neonates born at later gestational ages (GAs).

Methods: We included 97 preterm infants of 24-36 weeks GA. We performed neurosonography and EEG recordings at week 1 and 2 of postnatal life, then every two weeks until term conceptional age (CA).

CNS siderosis and dandy-walker variant after neonatal alloimmune thrombocytopenia.

This report presents a case of superficial siderosis of the central nervous system secondary to repeated intraventricular and subarachnoid bleeding of a newborn infant with neonatal alloimmune thrombocytopenia. In addition, this infant manifested Dandy-Walker variant. To date, the few known cases of superficial siderosis in neonates have not been associated with neonatal alloimmune thrombocytopenia or Dandy-Walker complex.

Positive temporal sharp waves in preterm infants with and without brain ultrasound lesions.

Objective: Clinical significance of neonatal positive temporal sharp waves (PTS) is controversial. The aim of this work is to study (1) PTS incidence in preterm infants with or without major ultrasound lesion (MUL) per gestational age (GA), and (2) the relationship between PTS in both sleep states and other electroencephalographic (EEG) findings with poor prognoses.

Methods: 97 preterm infants of <27-36 weeks GA, and 12 full-term healthy infants were presented.