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Among various hybrid nanomaterials, the combination of plasmonic nanoparticles and fluorophores in a single multifunctional nanoplatform, so‐called plasmophores, has attracted significant attention in different fields such as dark field, fluorescence, and photoacoustic imaging, biosensing, photothermal, and photodynamic therapy. Herein, author report a facile and controlled synthesis route of hybrid nanoplatforms composed of fluorescent gold nanoclusters (GNCs) coupled to plasmonic gold nanorods (GNRs) using controlled silica (SiO2) dielectric spacers of different thicknesses from now on referred to as GNR@SiO2@GNC plasmophores. The results show different degrees of plasmon‐enhanced fluorescence of the GNCs in their plasmophore hybrid system when placed at different distances from the plasmonic cores of the GNRs. On the other hand, these plasmophores show enhanced thermal stability compared to GNRs@CTAB (CTAB, cetyl trimethyl ammonium bromide). This results also demonstrated that upon annealing at elevated temperatures (800–1000 °C), the GNRs in the plasmophores are more thermally stable and robust than the GNRs@CTAB. More surprisingly, despite the commonly reported very low melting temperature of smaller‐size nanocrystals, the GNCs in the plasmophores showed high thermal stability and do not exhibit significant structural changes at elevated temperatures (800–1000 °C). [ABSTRACT FROM AUTHOR]

Wearable flexible strain sensors with spatial resolution enable the acquisition and analysis of complex actions for noninvasive personalized healthcare applications. To provide secure contact with skin and to avoid environmental pollution after usage, sensors with biocompatibility and biodegradability are highly desirable. Herein, wearable flexible strain sensors composed of crosslinked gold nanoparticle (GNP) thin films as the active conductive layer and transparent biodegradable polyurethane (PU) films as the flexible substrate are developed. The patterned GNP films (micrometer‐ to millimeter‐scale square and rectangle geometry, alphabetic characters, and wave and array patterns) are transferred onto the biodegradable PU film via a facile, clean, rapid and high‐precision contact printing method, without the need of a sacrificial polymer carrier or organic solvents. The GNP‐PU strain sensor with low Young's modulus (≈17.8 MPa) and high stretchability showed good stability and durability (10 000 cycles) as well as degradability (42% weight loss after 17 days at 74 °C in water). The GNP‐PU strain sensor arrays with spatiotemporal strain resolution are applied as wearable eco‐friendly electronics for monitoring subtle physiological signals (e.g., mapping of arterial lines and sensing pulse waveforms) and large‐strain actions (e.g., finger bending). [ABSTRACT FROM AUTHOR]

We calculate the optical properties of InP and CdSe colloidal quantum dots (QDs) within the framework of the atomic effective pseudopotential approach and the screened configuration interaction theory. We obtain an excellent agreement with experiment with our microscopic and space-dependent screening function where the dielectric constant varies in real space with a sharp transition (width of ≈0.18 nm) from the QD material high-frequency bulk value inside the QD to the solvent or passivant high-frequency value outside. We obtain a reasonable agreement (with deviations less than 140 meV) for a computationally less demanding solvent-independent screening using the full high-frequency bulk screening, in contrast to the more commonly used reduced QD radius-dependent screening constant. We show theoretically that for QDs passivated with long-chained organic molecules, the influence of the solvent on the optical gap is in the range of 10 meV, while QDs passivated with short ligands can experience shifts in the order of 100 meV. Experiments on CdSe QDs passivated with octadecylphosphonic acid (ODPA, long-chained ligand) in two different solvents (toluene and chloroform) confirm the bandgap dependence. While the optical gap is weakly affected by the environment, the quasiparticle gap and the exciton binding energy show a strong environmental dependence. Finally, we show that the optical bandgap does not depend significantly on the crystal structure (wurtzite or zincblende) or the morphological details (faceted or "spherical" shape). [ABSTRACT FROM AUTHOR]

Catalyst layers made from novel catalysts must be fabricated in a way that the catalyst can function to its full potential. To characterize a PtNi alloy catalyst for use in the cathode of Direct Methanol Fuel Cells (DMFCs), the effects of the manufacturing technique, ink composition, layer composition, and catalyst loading were here studied in order to reach the maximum performance potential of the catalyst. For a more detailed understanding, beyond the DMFCs performance measurements, we look at the electrochemically active surface area of the catalyst and charge-transfer resistance, as well as the layer quality and ink properties, and relate them to the aspects stated above. As a result, we make catalyst layers with optimized parameters by ultrasonic spray coating that shows the high performance of the catalyst even when containing less Pt than commercial products. Using this approach, we can adjust the catalyst layers to the requirements of DMFCs, hydrogen fuel cells, or polymer electrolyte membrane electrolysis cells. [ABSTRACT FROM AUTHOR]

With the development of X-ray free-electron lasers (XFELs), producing pulses of femtosecond durations comparable with the coherence times of X-ray fluorescence, it has become possible to observe intensity-intensity correlations due to the interference of emission from independent atoms. This has been used to compare durations of X-ray pulses and to measure the size of a focused X-ray beam, for example. Here it is shown that it is also possible to observe the interference of fluorescence photons through the measurement of the speckle contrast of angle-resolved fluorescence patterns. Speckle contrast is often used as a measure of the degree of coherence of the incident beam or the fluctuations of the illuminated sample as determined from X-ray diffraction patterns formed by elastic scattering, rather than from fluorescence patterns as addressed here. Commonly used approaches to estimate speckle contrast were found to suffer when applied to XFEL-generated fluorescence patterns due to low photon counts and a significant variation of the excitation pulse energy from shot to shot. A new method to reliably estimate speckle contrast under such conditions, using a weighting scheme, is introduced. The method is demonstrated by comparing the speckle contrast of fluorescence observed with pulses of 3 fs to 15 fs duration. [ABSTRACT FROM AUTHOR]

AbstractJudicious selection of the amount of surfactant during synthesis enables a drastic increase in the photoluminescence efficiency of aqueous CdTe nanocrystals (NCs) stabilized by thioglycolic acid (TGA). Elemental determination of the NCs was undertaken to identify the origin of this effect. The molar ratio of (Te + S) to Cd approached unity when the optimum amount of TGA was used during synthesis, whereas the number of S atoms originating from TGA molecules in one NC (2.6 nm of diameter) remained unchanged at 90 ± 3. This indicates that the core lattice composition at the beginning of synthesis, rather than the surface conditions, affects the photoluminescence efficiency of the NCs even after prolonged refluxing.

The spin‐dependent electrical transport in rigid inorganic‐inorganic layered systems is extensively applied for the detection of magnetic fields in data storage. In this work, spin‐dependent electrical transport in flexible organic‐inorganic supercrystals based on superparamagnetic iron oxide nanoparticles is investigated. These nanoparticles are stabilized by oleic acid ligands, which in turn are serving as tunneling barriers between individual magnetic nanoparticles. The resulting tunneling magnetoresistance (TMR) is tunable due to the elastic properties of these organic barriers. Applying external mechanical stress on this composite material will change the average distance between adjacent nanoparticles and will hence determine the resulting TMR‐effect amplitude. Thus, measured stress‐induced changes in the barrier thickness at sub‐nanometer scale allow for determining the mechanical properties of organic barrier molecules in the confined space between the particles. These results provide the foundation for a new type of mechanical sensor. [ABSTRACT FROM AUTHOR]

Controlled assembly of gold nanoparticles (AuNPs) into clusters is a promising avenue for the development of sensitive bioimaging and diagnostic tools based on surface‐enhanced Raman scattering (SERS). However, several challenges, such as biocompatibility or colloidal and structural stability in biological environments, remain before AuNPs can be used as a tool for in vivo bioimaging. A versatile strategy for the preparation of colloidally stable and biocompatible AuNP clusters (AuNPCs) is introduced with high SERS signals, which are used as SERS contrast bioimaging agents (SERS tags). By tuning the ligand ratio of Raman reporter molecules to stabilizing polymer on the surface of each AuNP, aggregation can be carefully controlled. The resulting AuNPCs exhibit redshifted surface plasmon resonances in the near‐infrared (NIR) region, as well as distinct electromagnetic hotspots that give rise to SERS analytical enhancement factors above 104, compared to non‐clustered spherical AuNPs. Thanks to the protective polymer shell, high levels of cellular uptake with low cytotoxicity are observed, allowing 3D SERS mapping of cells with sufficiently high spatial resolution to detect AuNPCs within intracellular organelles. [ABSTRACT FROM AUTHOR]

Brown adipose tissue (BAT) burns fatty acids for heat production to defend the body against cold (1,2) and has recently been shown to be present in humans (3-5). Triglyceride-rich lipoproteins (TRLs) transport lipids in the bloodstream, where the fatty acid moieties are liberated by the action of lipoprotein lipase (LPL) (6). Peripheral organs such as muscle and adipose tissue take up the fatty acids, whereas the remaining cholesterol-rich remnant particles are cleared by the liver (6). Elevated plasma triglyceride concentrations and prolonged circulation of cholesterol-rich remnants, especially in diabetic dyslipidemia, are risk factors for cardiovascular disease (7-11). However, the precise biological role of BAT for TRL clearance remains unclear. Here we show that increased BAT activity induced by short-term cold exposure controls TRL metabolism in mice. Cold exposure drastically accelerated plasma clearance of triglycerides as a result of increased uptake into BAT, a process crucially dependent on local LPL activity and transmembrane receptor CD36. In pathophysiological settings, cold exposure corrected hyperlipidemia and improved deleterious effects of insulin resistance. In conclusion, BAT activity controls vascular lipoprotein homeostasis by inducing a metabolic program that boosts TRL turnover and channels lipids into BAT. Activation of BAT might be a therapeutic approach to reduce elevated triglyceride concentrations and combat obesity in humans., Although white adipose tissue is a specialized lipid storage organ for excess calories, BAT contains large amounts of mitochondria to dissipate chemical energy. Upon cold-stimulated activation by nervous input, BAT [...]

The inter-nanocrystals (NCs) interactions among pristine assemblies, electrostatically mixed assemblies, and covalently linked NCs assemblies of CdTe NCs stabilized with thioamine and thio acid surfactants were compared. The spectral overlaps between the adsorption and emission curves, the PL red shift, the PL decay curves, and the calculated FRET revealed that covalently linked NCs have the strongest inter-NCs interaction, while CdTe(TGA) NCs act as the most efficient donors.

The interplay between Auger effects and ionization processes are studied in the limit of strong electronic confinement in core/shell CdSe/ZnS semiconductor nanocrystal quantum dots. The results suggest that Auger recombination accelerates ionization processes that lead to the occupation of dark, nonemissive nanocrystal states.

The self-organization of CdSe nanorods into nematic, smectic, and crystalline solids is demonstrated. The colloidal crystals of nanorods show characteristic birefringence, which is assigned to specific spherulite-like texture of each nanorod assembly.

The energy transfer between polystyrene beads coated with CdTe as donors and Alexaflour molecules as acceptors is analyzed. The study demonstrated that the system is a very promising candidate for fluorescence-resonance energy transfer (FRET)- scanning near-field optical microscopy (SNOM) applications and single molecules.

A comparison is made of the optical and electrical properties of 11-20 nm thick films composed of ~4 nm gold nanoparticles (Au-NPs) by six organic dithiol or bis-dithiocarbonate derivatives. The results suggest that the nonresonant tunneling along the nonconjugated parts of the molecule govern the electron tunneling decay constant.

A novel chemical route in homogeneous solution for well-crystallized anatase TiO2 nanorods under easily controlled and mild conditions is presented. The fundamental factors affecting the growth and crystallinity of Tio2 particles are investigated by simple variation of the synthesis conditions.

A theoretical model for the formation and dissolution of nanoparticles in solution is presented. It is shown that the particle formation process consists of a nucleation phase and a phase of Ostwald ripening and the dissolution process of a given amount of particles can be modeled.

Colloidally prepared CdTe nanocrystals are studied. A photoemission study was performed to reveal if there are structural differences in the nanocrystals and a structure model is proposed to explain the differences in luminescence efficiency.

Photoluminescence efficiency of Inp nanocrystals prepared via the dehalosilylation reaction between indium chloride and tris- (trimethylsilyl) phosphine in mixtures of trioctylphosphine and trioctylphosphine oxide can be drastically improved by etching with fluorine compounds. The pure photochemical nature of etching process allowed improving its reproducibility and reliability.

The swelling behavior of clay minerals by a combination of molecular dynamics and Monte Carlo sampling techniques is addressed. The result reveals that the extent of clay swelling strongly depends on the charge locus.

Photoluminescence efficiency of Inp nanocrystals prepared via the dehalosilylation reaction between indium chloride and tris- (trimethylsilyl) phosphine in mixtures of trioctylphosphine and trioctylphosphine oxide can be drastically improved by etching with fluorine compounds. The pure photochemical nature of etching process allowed improving its reproducibility and reliability.

The charge transport in nanoparticulate ZnO layers held at different potentials is studied by analyzing the anodic transient photocurrents. The results reveal that the effective diffusion constant for the electron transport through ZnO film held at positive potentials is calculated to be 1.7 x 10(super -4) cm(super 2)/s which is in good agreement with diffusion constants.

Interactions in semiconductor nanocrystal assemblies are studied on films of the cluster crystal compounds Cd17S4(SCH2CH2OH)(sub 26) and Cd32S14(SCH2CH(CH3)OH)(sub 36) prepared by spin coating. The redshift of the transition energy is explained by dipole-dipole interactions of the semiconductor nanocrystals in the films.

The investigations made on the particle properties, which show variations within the ensembles of colloidal II-VI and III-V semiconductor nanocrystals, are reported. A theoretical model is explained, which describes the evolution of an ensemble of nanocrystals in a colloidal solution.

The results are presented of the electroluminescence of CdTe nanocrystals inserted into ultrathin, self-assembled films.