Topological Susceptibility under Gradient Flow

We study the impact of the Gradient Flow on the topology in various models of lattice field theory. The topological susceptibility $\chi_{\rm t}$ is measured directly, and by the slab method, which is based on the topological content of sub-volumes ("slabs") and estimates $\chi_{\rm t}$ even when the system remains trapped in a fixed topological sector. The results obtained by both methods are essentially consistent, but the impact of the Gradient Flow on the characteristic quantity of the slab method seems to be different in 2-flavour QCD and in the 2d O(3) model. In the latter model, we further address the question whether or not the Gradient Flow leads to a finite continuum limit of the topological susceptibility (rescaled by the correlation length squared, $\xi^{2}$). This ongoing study is based on direct measurements of $\chi_{\rm t}$ in $L \times L$ lattices, at $L/\xi \simeq 6$.Comment: 8 pages, LaTex, 5 figures, talk presented at the 35th International Symposium on Lattice Field Theory, June 18-24, 2017, Granada, Spai

Self-Precipitation of Highly Purified Red Emitting Carbon Dots as Red Phosphors

Colloidal carbon dots (C-dots) have attracted a great deal of attention for their unique optical properties. However, it is still a challenge to obtain highly purified C-dots without using multiple-step purification or postsize selection. In this work, a self-precipitation hydrothermal reaction was used to synthesize red-emitting C-dots (R-C-dots) using o-phenylenediamine (o-PDA) as a precursor without using any catalyst. The R-C-dots are able to precipitate on the wall of the reactor, which enables us to obtain solid-state C-dots with high purity. The R-C-dots have a photoluminescence quantum yield (PLQY) of as high as 36.75%, which is among the highest PLQY values reported previously for R-C-dots without using catalysts. The transient PL and transient absorption spectra revealed that 5,14-dihydroquinoxalino[2,3-b]phenazine linked on the surface of the C-dots determined the red luminescence behavior. This work provides a new path for the controllable synthesis of high-purity R-C-dots, showing potential applications in optoelectronic devices

Self-Precipitation of Highly Purified Red Emitting Carbon Dots as Red Phosphors

Colloidal carbon dots (C-dots) have attracted a great deal of attention for their unique optical properties. However, it is still a challenge to obtain highly purified C-dots without using multiple-step purification or postsize selection. In this work, a self-precipitation hydrothermal reaction was used to synthesize red-emitting C-dots (R-C-dots) using o-phenylenediamine (o-PDA) as a precursor without using any catalyst. The R-C-dots are able to precipitate on the wall of the reactor, which enables us to obtain solid-state C-dots with high purity. The R-C-dots have a photoluminescence quantum yield (PLQY) of as high as 36.75%, which is among the highest PLQY values reported previously for R-C-dots without using catalysts. The transient PL and transient absorption spectra revealed that 5,14-dihydroquinoxalino[2,3-b]phenazine linked on the surface of the C-dots determined the red luminescence behavior. This work provides a new path for the controllable synthesis of high-purity R-C-dots, showing potential applications in optoelectronic devices

Tuning the Charge-Transfer Property of PbS-Quantum Dot/TiO₂-Nanobelt Nanohybrids via Quantum Confinement

A newly designed photoactive nanohybrid structure based on the combination of near-infrared PbS quantum dots (QDs) as light harvester and one-dimensional TiO₂ nanobelts (NBs) to guide the flow of photogenerated charge carriers is reported. Efficient electron transfer from photoexcited PbS QDs to TiO₂ NBs has been demonstrated to occur in the developed PbS-QD/TiO₂-NB nanohybrids, and the charge-transfer property can be tuned through the size quantization effect of PbS QDs. Moreover, the use of TiO₂ NBs instead of TiO₂ NPs permits a larger critical size of PbS QDs capable of injecting electrons into TiO₂ NBs, which, in turn, markedly extends the “effective” absorption of the PbS-QD/TiO₂-NB nanohybrids to a longer wavelength region up to 1400 nm. Such an extension of the “effective” absorption is a major asset for improving the overall photoconversion efficiency of PbS-QD/TiO₂-NB nanohybrids-based photovoltaic devices

Size Dependence of Temperature-Related Optical Properties of PbS and PbS/CdS Core/Shell Quantum Dots

The effect of PbS core size on the temperature-dependent photoluminescence (PL) of PbS/CdS quantum dots (QDs) in the temperature range of 100–300 K was thoroughly investigated and compared with shell-free PbS QDs. The core/shell QDs show significantly smaller PL intensity variation with temperature at a smaller PbS size, while a larger activation energy when the PbS domain size is relatively large, suggesting both different density and different distribution of defects/traps in the PbS and PbS/CdS QDs. The most remarkable difference consists in the PbS size dependence of the energy gap temperature coefficient (d<i>E</i>/d<i>T</i>). The PbS/CdS QDs show unusual non-monotonic d<i>E</i>/d<i>T</i> variation, resulting in the reversal of the d<i>E</i>/d<i>T</i> difference between the PbS and PbS/CdS QDs at a larger PbS size. In combination with theoretical calculations, we find that, although lattice dilation and carrier-phonon coupling are generally considered as dominant terms, the unique negative contribution to d<i>E</i>/d<i>T</i> from the core/shell interfacial strain becomes most important in the relatively larger-core PbS@CdS QDs

Silver Nanorice Structures: Oriented Attachment-Dominated Growth, High Environmental Sensitivity, and Real-Space Visualization of Multipolar Resonances

We have synthesized and investigated the anisotropic growth of interesting silver nanorice. Its growth is kinetically controlled at 100 °C, and both oriented attachment and Ostwald ripening are involved, with the former growth mode dominating the anisotropic growth of the nanorice along the ⟨111⟩ direction. This one-directional growth is initiated by an indispensable seed-selection process, in which oxygen plays a critical role in oxidatively etching twinned silver crystals. The inhibition of this process by removing oxygen essentially blocks the nanorice growth. Although increasing reaction temperature to 120 °C accelerates the one-dimensional growth along the ⟨111⟩ direction, further temperature increase to 160 °C makes the oriented attachment dominated one-directional growth disappear; instead, the diffusion-controlled two-dimensional growth leads to the emergence of highly faceted truncated triangular and hexagonal plates mainly bound by low energy faces of {111}. Interestingly, we also found that the longitudinal surface plasmon resonance of the nanorice structures is highly sensitive to the refractive index of surrounding dielectric media, which predicts their promising applications as chemical or biological sensors. Moreover, the multipolar plasmonic resonances in these individual nanorice structures are visualized in real space, using high-resolution electron energy-loss spectroscopy

Asymmetric Silver “Nanocarrot” Structures: Solution Synthesis and Their Asymmetric Plasmonic Resonances

Here we report the wet-chemical synthesis of asymmetric one-dimensional (1D) silver “nanocarrot” structures that exhibit mixed twins and stacking fault domains along the ⟨111⟩ direction. Oriented attachment is the dominant mechanism for anisotropic growth. Multipolar plasmon resonances up to fourth order were measured by optical extinction spectroscopy and electron energy-loss spectroscopy (EELS) and are in agreement with theoretical calculations. Compared with those of symmetric 1D nanostructures of similar length, the dipole modes of the nanocarrots show a clear red shift, and the EELS maps show an asymmetric distribution of the resonant plasmonic fields and a compression of the resonance node spacing toward the tail. In addition, increasing the length of the nanocarrots causes an increase in the intensity and a steady red shift of the longitudinal surface plasmon resonance peaks. The silver nanocarrots also show very high sensitivity to the refractive index of their environment (890 ± 87 nm per refractive index unit)

Peripheral arterial occlusive disease: Global gene expression analyses suggest a major role for immune and inflammatory responses-2

a Venn diagram. B, C. Heatmap representation of commonly up-regulated genes (B) and commonly down-regulated genes (C) in overlapping genes, respectively. Samples are displayed in columns and genes in rows. Gene expression is represented as a color, normalized across each row, with brighter red for higher values and brighter green for lower values. Gene symbols are listed to the right. N (Normal control group), Int (intermediate lesions group), Ad (advanced lesions group).<p><b>Copyright information:</b></p><p>Taken from "Peripheral arterial occlusive disease: Global gene expression analyses suggest a major role for immune and inflammatory responses"</p><p>http://www.biomedcentral.com/1471-2164/9/369</p><p>BMC Genomics 2008;9():369-369.</p><p>Published online 1 Aug 2008</p><p>PMCID:PMC2529314.</p><p></p

Peripheral arterial occlusive disease: Global gene expression analyses suggest a major role for immune and inflammatory responses-7

S illustrated with significantly regulated genes highlighted.<p><b>Copyright information:</b></p><p>Taken from "Peripheral arterial occlusive disease: Global gene expression analyses suggest a major role for immune and inflammatory responses"</p><p>http://www.biomedcentral.com/1471-2164/9/369</p><p>BMC Genomics 2008;9():369-369.</p><p>Published online 1 Aug 2008</p><p>PMCID:PMC2529314.</p><p></p

Peripheral arterial occlusive disease: Global gene expression analyses suggest a major role for immune and inflammatory responses-0

8 um cryostat sections were stained with hematoxylin and eosin, dehydrated in graded alcohol, and cover-slipped with permanent mounting solution after xylene clearing. Three representative samples are listed: normal artery (A, B, C), intermediate lesions (D, E, F), and advanced lesions (G, H, I).<p><b>Copyright information:</b></p><p>Taken from "Peripheral arterial occlusive disease: Global gene expression analyses suggest a major role for immune and inflammatory responses"</p><p>http://www.biomedcentral.com/1471-2164/9/369</p><p>BMC Genomics 2008;9():369-369.</p><p>Published online 1 Aug 2008</p><p>PMCID:PMC2529314.</p><p></p