Nanophotonic droplet: a nanometric optical device consisting of size- and number-selective coupled quantum dots

Although recent advances in fabrication technologies have allowed the realization of highly accurate nanometric devices and systems, most approaches still lack uniformity and mass-production capability sufficient for practical use. We have previously demonstrated a novel technique for autonomously coupling heterogeneous quantum dots to induce particular optical responses based on a simple phonon-assisted photocuring method in which a mixture of quantum dots and photocurable polymer is irradiated with light. The cured polymer sequentially encapsulates coupled quantum dots, forming what we call a nanophotonic droplet. Recently, we found that each quantum dot in the mixture is preferably coupled with other quantum dots of similar size due to a size resonance effect of the optical near-field interactions between them. Moreover, every nanophotonic droplet is likely to contain the same number of coupled quantum dots. In this paper, we describe the basic mechanisms of autonomously fabricating nanophotonic droplets, and we examine the size- and number-selectivity of the quantum dots during their coupling process. The results from experiments show the uniformity of the optical properties of mass-produced nanophotonic droplets, revealed by emission from the contained coupled quantum dots, due to the fundamental characteristics of our method.     

New Raman Spectroscopic Data of the Almahata Sitta Meteorite

The archaeological site of Pintia (Padilla de Duero/Peñafiel, Valladolid), considered one of the first cities on the Iberian Peninsula, has yielded very interesting archaeological records regarding the different functional areas that involve the oppidum. Pottery, metal, and bone/skeletal remains are very well preserved, being optimal for analysis and study of the ancient food contained, such as milk-based products, animal fats, beer, and wine. The combination of Raman Microscopy (RM) with other analytical techniques such as Light Microscopy (LM) and Environmental Scanning Electron Microscopy equipped with Energy Dispersive X-ray Spectroscopy (ESEM-EDX) becomes a powerful tool to obtain information on the possible content in the ceramic receptacles from historical-archaeological heritage. It can lead to an interpretation of their specific use or functionality. In this work, a unique sample preparation was used for all techniques, which lead to a very simple procedure and documentation. The degradation and aging of natural fibers and the presence of organic matter with low crystallinity and calcium oxalate–related residuals can be studied by these combined techniques. The archaeological residuals can be separated from modern contamination coming from agriculture processes, surrounding land minerals, or fresh vegetal matter.     

Impaired pulmonary blood flow distribution in congestive heart failure assessed using synchrotron radiation microangiography

Synchrotron radiation microangiography is a powerful tool for assessing adverse changes in pulmonary vessel density associated with primary pulmonary hypertension (PH). Congestive heart failure (CHF) leads to a `secondary' onset of PH, yet it is unknown whether secondary PH is also associated with reduced vessel density. This study utilized synchrotron radiation to assess both pulmonary vessel density and endothelial function in a Dahl rat model of CHF with secondary PH. High salt‐fed Dahl salt‐sensitive (Dahl‐S) and salt‐resistant (Dahl‐R) rats were anesthetized and microangiography was performed to assess the pulmonary vessel density and vascular responses to (i) sodium nitroprusside (5.0 µg kg^?1 min^?1), (ii) acetylcholine (3.0 µg kg^?1 min^?1) and (iii) ET‐1_A receptor blockade, BQ‐123 (1 mg kg^?1). Dahl‐S rats developed CHF and secondary PH as evident by endothelial dysfunction, impaired vasodilatory responses to acetylcholine, enhanced vasodilatory responses to BQ‐123 and extensive pulmonary vascular remodeling. Consequently, the pulmonary vessel density was adversely reduced. Interestingly, the etiology of secondary PH manifests with structural and functional changes that are comparable with that previously reported for primary PH. One important discrepancy, however, is that ET‐1 modulation of pulmonary vessels is most striking in vessels with a diameter range of 100–200 µm in secondary PH, in contrast to a range of 200–300 µm in primary PH. Such discrepancies should be considered in future studies investigating primary and secondary forms of PH.     

Study of alkyl chain length dependent characteristics of imidazolium based ionic liquids [CnMIM]+[TFSA]− by Brillouin and dielectric loss spectroscopy

This study examined the acoustic phonon mode of ionic liquids consisting of 1-alkyl-3-methyl-imidazolium family (C_nMIM) cations with n values ranging from 2 to 10 and bis(trifluoromethylsulfonyl)amide (TFSA) anion in the temperature range from 300 K to 100 K. [C_nMIM]⁺[TFSA]^? showed depolarized (VH) components of Brillouin peaks at temperatures below the glass transition temperature when n is larger than 4. On the other hand, in the case of ionic liquids with different anions, such as [C₄MIM]⁺[BF₄]^?, [C₄MIM]⁺[PF₆]^? and [C₈MIM]⁺[BF₄]^?, the VH component of Brillouin peaks was not observed in the temperature range investigated. The dielectric loss spectra showed that the temperature dependence of alkyl chain domain relaxation of all ionic liquids followed the Arrhenius law and showed an increase in activation energy at the temperature where the VH component of Brillouin peak appeared. These results suggest that the observed depolarized component of Brillouin peak might originate from uniquely induced polarization in the 2nd domain composed of head groups of cations and anions.     

DFT calculations for Au adsorption onto a reduced TiO2 (110) surface with the coexistence of Cl

Residual chlorines, which originate from HAuCl₄, enhance the aggregation of gold (Au) nanoparticles and clusters, preventing the generation of highly active supported Au catalysts. However, the detailed mechanism of residual-chlorine-promoted aggregation of Au is unknown. Herein to investigate this mechanism, density functional theory (DFT) calculations of Au and Cl adsorption onto a reduced rutile TiO₂ (110) surface were performed using a generalised gradient approximation Perdew, Burke, and Ernzerhof formula (GGA–PBE) functional and plane-wave basis. Although both Au and Cl atoms prefer to mono-absorb onto oxygen defect sites, Cl atoms have a stronger absorption onto a reduced TiO₂ (110) surface, abbreviated as rTiO₂ (110) in the following, than Au atoms. Additionally, co-adsorption of a Cl atom and a Au atom or Au nanorod onto a rTiO₂ surface was investigated; Cl adsorption onto an oxygen defect site weakens the interaction between a Au atom or Au nanorod and rTiO₂ (110) surface. The calculation results suggest that the depletion of interaction between Au and rTiO₂ surface is due to strong interaction between Cl atoms at oxygen defect sites and neighbouring bridging oxygen (O^B) atoms.     

Enhancement of Magneto-Optic Effect in Optical Isolator with Semiconductor Guiding Layer by Selective Oxidation of AlInAs

Selective oxidation of an AlInAs layer was investigated for enhancement of magneto-optic effect in an optical isolator. Twelve times nonreciprocal phase shift enhancement was estimated from a measured AlInAs-oxide refractive index.     

Dose-dependent inhibition of ultrasound-induced cell killing and free radical production by carbon dioxide

Previous studies have shown that if a solution for cell suspension is saturated with CO(2), ultrasound-induced in vitro cell killing and free-radical production are inhibited. However, the dose dependency of this observation has not been explored. Here, we used NaHCO(3) and HCl to produce a predictable concentration of CO(2) within the culture medium. Using 1 MHz continuous wave 4 W/cm(2) ultrasound, we sonicated U937 cells suspension for 1 min at 37 degrees C with CO(2) at different concentrations. At 2 mM, reduced cell killing was observed that further decreased with increasing CO(2) concentration until 100% protection was attained at 20 mM. Ultrasound-induced free-radical production was significantly decreased at 1 mM and became undetectable at 2 mM CO(2). This finding shows that CO(2)-mediated inhibition is concentration dependent and that the threshold for free-radical production is one order of magnitude higher than the threshold for cell killing induced by ultrasound. In addition, it also cautions researchers when adding acids and acid-based agents to a culture medium, which almost always contains NaHCO(3), in experiments related to the bioeffects of ultrasound.     

Asymptotic behavior in chemical reaction-diffusion systems with boundary equilibria

We consider the asymptotic behavior for large time of solutions to reaction-diffusion systems modeling reversible chemical reactions. We focus on the case where multiple equilibria exist. In this case, due to the existence of so-called "boundary equilibria", the analysis of the asymptotic behavior is not obvious. The solution is understood in a weak sense as a limit of adequate approximate solutions. We prove that this solution converges in L^1 toward an equilibrium as time goes to infinity and that the convergence is exponential if the limit is strictly positive.