Bottomonium Studies at Belle Garmash, A
EPJ Web of Conferences,
2015, Letnik:
96
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Recent results on studies of bottomonium and bottomonium-like states at Belle are reported. The results are obtained with a 121.4 fb−1 data sample collected with the Belle detector in the vicinity of ...the ϒ(5S) resonance at the KEKB asymmetric-energy e+e− collider.
Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5–5 Torr), we fabricated substrate-supported silicon (Si) ...nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the “red - near infrared” (maximum at 760 nm) and “green” (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense “green-yellow” PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.
The paper presents the results of investigation of the possibility of using textural statistical features to classify the images of ultrasound diagnostics of thyroid nodules. Ultrasound diagnostics ...has a significant potential for quantitative diagnostics. New information technologies allow us to identify characteristics that complement the classical methods of image analysis in medicine.
Due to particular physico-chemical characteristics and prominent optical properties, nanostructured germanium (Ge) appears as a promising material for biomedical applications, but its use in ...biological systems has been limited so far due to the difficulty of preparation of Ge nanostructures in a pure, uncontaminated state. Here, we explored the fabrication of Ge nanoparticles (NPs) using methods of pulsed laser ablation in ambient gas (He or He-N2 mixtures) maintained at low residual pressures (1–5 Torr). We show that the ablated material can be deposited on a substrate (silicon wafer in our case) to form a nanostructured thin film, which can then be ground in ethanol by ultrasound to form a stable suspension of Ge NPs. It was found that these formed NPs have a wide size dispersion, with sizes between a few nm and hundreds of nm, while a subsequent centrifugation step renders possible the selection of one or another NP size fraction. Structural characterization of NPs showed that they are composed of aggregations of Ge crystals, covered by an oxide shell. Solutions of the prepared NPs exhibited largely dominating photoluminescence (PL) around 450 nm, attributed to defects in the germanium oxide shell, while a separated fraction of relatively small (5–10 nm) NPs exhibited a red-shifted PL band around 725 nm under 633 nm excitation, which could be attributed to quantum confinement effects. It was also found that the formed NPs exhibit high absorption in the visible and near-IR spectral ranges and can be strongly heated under photoexcitation in the region of relative tissue transparency, which opens access to phototherapy functionality. Combining imaging and therapy functionalities in the biological transparency window, laser-synthesized Ge NPs present a novel promising object for cancer theranostics.
The effect of laser radiation parameters on properties of bismuth (Bi) nanoparticles (NPs) produced by pulsed laser ablation in liquids (PLAL) was studied. We demonstrated that the average NPs size ...increases under the increase of laser radiation energy and the decrease in the distance from the focusing lens to the target surface. The obtained results provide a tool for a controllable synthesis of new functional nanomaterials for biomedical applications.
Abstract
We elaborated a technique of pulsed laser ablation in gas mixtures (He-N
2
), maintained under residual pressures of 0.5–5 Torr to deposit silicon (Si)-based nanostructured films on a ...substrate. We show that the deposited films can exhibit strong photoluminescence (PL) emission with the position of peaks depending on the pressure of ambient gas and the ratio of gases in the mixture. Nanostructured films prepared in pure He gas exhibited a strong band in the infrared range (around 760 nm) and a weak band in the green range (550 nm), which were attributed to quantum-confined excitonic states in small Si nanocrystals and radiative transitions via the localized electronic states in silicon suboxide coating, respectively. In contrast, nanostructured films prepared in He-N
2
mixtures exhibited more intense “green-yellow” PL band centered at 580 nm, which was attributed to a radiative recombination in amorphous oxynitride (a-SiN
x
O
y
) coating of Si nanocrystals. We also present a detailed analysis of morphology of nanostructures Si-based films prepared by laser ablation. Finally, we show that the nanocrystals can be removed from the substrate and milled by ultrasound to form aqueous solutions of colloidal Si nanopartiles. The fabricated Si-based nanocrystals present a promising object for theranostics, combining imaging functionality based on PL emission and a series of therapy functionalities (photo and radiofrequency hyperthermia, photodynamic therapy).
Photothermal properties of boron (B) nanoparticles (NPs) synthesized by pulsed laser ablation in liquid (PLAL) are studied. It is found that B NPs have high optical extinction coefficient in the near ...infrared (IR) region, in particular, its value was 0.2 l/(cm g) at a wavelength of 800 nm. It is shown that aqueous suspensions of B NPs can be heated during laser irradiation with a wavelength of 830 nm and a radiation power of 1 W. Here, the temperature increase varied from 6.5 to 36°C under the increase of the particle concentration from 0.04 to 0.8 g/L; while the relevant parameter in the absence of particles was 2°C. B NPs were able to provide a stable photothermal response during several irradiation cycles. The results evidence a high potential of B NPs as sensitizers of photothermal therapy (PTT).
We present the first model-independent measurement of the CKM unitarity triangle angle ϕ3 using B±→ D(KS0\ {K}_{\mathrm{S}}^0 \π+π−π0) K± decays, where D indicates either a D0 or D¯\ \overline{D} \0 ...meson. Measurements of the strong-phase difference of the D →KS0\ {K}_{\mathrm{S}}^0 \π+π−π0 amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of 772 × 106BB¯\ \overline{B} \ events collected at the Υ(4S) resonance. We obtain ϕ3 = (5.7−8.8+10.2\ {5.7}_{-8.8}^{+10.2} \±3.5±5.7)° and the suppressed amplitude ratio rB = 0.323±0.147±0.023±0.051. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on ϕ3 is (−29.7, 109.5)°, which is consistent with the current world average.
Experimental and kinetic modeling study of the ignition of a stoichiometric mixture of acetone with oxygen diluted by argon was carried out behind reflected shock waves within the temperature range ...of 1350-1810 K for the total mixture concentration M50 ~ 10-5 mol/cm3. Emission signals were recorded simultaneously for three different wavelengths: OH* (λ = 308 nm) and CO 2 * (λ1 = 365 nm; λ2 = 451 nm). It was revealed that the time it takes to reach the maximum of emission of OH* and CO 2 * is practically the same over the whole temperature range. At the same time, the emission profiles of CO 2 * after the maximum was attained, recorded at λ2 = 451 nm, differ noticeably from the profiles recorded at λ1 = 365 nm. For numerical modeling of the emission profiles of OH* and CO 2 * , the corresponding sets of excitation and quenching reactions available in the literature were used. In the course of our numerical simulations we succeeded in good agreement of our own experimental and simulation results on acetone ignition and the results available in the literature for conditions under consideration.
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