Scaling behaviors of heavy flavor meson suppression and flow in different nuclear collision systems at the LHC

We explore the system size dependence of heavy-quark-QGP interaction by studying the heavy flavor meson suppression and elliptic flow in Pb–Pb, Xe–Xe, Ar–Ar and O–O collisions at the LHC. The space-time evolution of the QGP is simulated using a $$(3+1)$$ ( 3 + 1 ) -dimensional viscous hydrodynamic model, while the heavy-quark-QGP interaction is described by an improved Langevin approach that includes both collisional and radiative energy loss inside a thermal medium. Within this framework, we provides a reasonable description of the D meson suppression and flow coefficients in Pb–Pb collisions, as well as predictions for both D and B meson observables in other collision systems yet to be measured. We find a clear hierarchy for the heavy meson suppression with respect to the size of the colliding nuclei, while their elliptic flow coefficient relies on both the system size and the geometric anisotropy of the QGP. Sizable suppression and flow are predicted for both D and B mesons in O–O collisions, which serve as a crucial bridge of jet quenching between large and small collision systems. Scaling behaviors between different collision systems are shown for heavy meson suppression factor and the bulk-eccentricity-rescaled heavy meson elliptic flow as functions of the number of participant nucleons in heavy-ion collisions.

Non-Radiative Recombination of Triplet Charge-Transfer State as the Key of Limiting Efficiency Mediates the Positive Relevance of JSC and VOC

Non-fullerene organic solar cells (NF OSCs) with A-D-A acceptors have realized the positive relevance of short-circuit current density (JSC) and open-circuit voltage (VOC), because of the restricted energy loss. However, non-radiative energy loss remains unclear, resulting in the positive relevance could not maximize power conversion efficiency (PCE). Here, the impact of non-radiative recombination directly related to the singlet- and triplet-charge-transfer (1CT and 3CT) states on the positive relevance is explored. It establishes the essential connection between 3CT-state non-radiation and positive relevance, points out the former mainly hinders PCE. The root reason is that decisive factors of decay rates in two pathways are completely different, but hard to adjust coordinately. Especially, another trade-off is still detected in NF OSCs, causing a bottleneck in PCE. To the end, we propose the defects of A-D-A molecular design by revealing 3CT-state non-radiation mediates the positive relevance.

Medium-induced radiative kernel with the Improved Opacity Expansion

We calculate the fully differential medium-induced radiative spectrum at next-to-leading order (NLO) accuracy within the Improved Opacity Expansion (IOE) framework. This scheme allows us to gain analytical control of the radiative spectrum at low and high gluon frequencies simultaneously. The high frequency regime can be obtained in the standard opacity expansion framework in which the resulting power series diverges at the characteristic frequency ωc ∼ $$ \hat{q} $$ q ̂ L2. In the IOE, all orders in opacity are resumed systematically below ωc yielding an asymptotic series controlled by logarithmically suppressed remainders down to the thermal scale T « ωc, while matching the opacity expansion at high frequency. Furthermore, we demonstrate that the IOE at NLO accuracy reproduces the characteristic Coulomb tail of the single hard scattering contribution as well as the Gaussian distribution resulting from multiple soft momentum exchanges. Finally, we compare our analytic scheme with a recent numerical solution, that includes a full resummation of multiple scatterings, for LHC-inspired medium parameters. We find a very good agreement both at low and high frequencies showcasing the performance of the IOE which provides for the first time accurate analytic formulas for radiative energy loss in the relevant perturbative kinematic regimes for dense media.

EXPRESS: A Lanthanide Complex Fluorescent Probe for the Detection of Melamine

Melamine is a kind of small molecule compound, which has been illegally adulterated in dairy food because of the rich nitrogen content and stable chemical properties. Therefore, the detection of melamine is of great significance to food safety and human's health protection. Melamine can emit weak fluorescence, making it difficult to detect melamine directly. However melamine can significantly enhance the emission of the tetracycline-europium (EuTC) complex at a wavelength of 616 nm, hence this work uses EuTC complex as a fluorescent probe to detect melamine. According to the characterizations of absorption spectra, molecular electrostatic potential distribution and the time-resolved spectra, we speculated that tetracycline and melamine may form a complex through hydrogen bonding interaction, causing the melamine closer approach to Eu3+ and reducing the non-radiative energy loss of water molecules to EuTC complex, which significantly enhanced the fluorescence intensity of EuTC. The fluorescence intensity with melamine concentration in the range of 0.5~40 μM shows a good linear relationship, and the correlation coefficient is 0.9951 with the detection limit of 0.0785 μM, which shows a high sensitivity in detection of melamine. As far as we know, EuTC complex is the first time that has been used as a fluorescent probe to detect melamine, which provides a supplement and extension for the detection of melamine in fluorescence spectroscopy.

Suppressing Energetic Disorder Enables Efficient Indoor Organic Photovoltaic Cells With a PTV Derivative

Indoor organic photovoltaics (IOPVs) cells have attracted considerable attention in the past few years. Herein, two PTV-derivatives, PTVT-V and PTVT-T, were used as donor materials to fabricate IOPV cells with ITCC as the acceptor. The preferred orientation of the crystals changed from edge-on to face-on after replacing the ethylene in the backbones of PTVT-V by the thiophene in that of PTVT-T. Besides, it was found that, the energetic disorder of the PTVT-T:ITCC based system is 58 meV, which is much lower than that of PTVT-V:ITCC-based system (70 meV). The lower energetic disorder in PTVT-T:ITCC leads to an efficient charge transfer, charge transport, and thus the weak charge recombination. As a result, a PCE of 9.60% under AM 1.5 G and a PCE of 24.27% under 1,000 lux (LED 2,700 K) with a low non-radiative energy loss of 0.210 eV were obtained based on PTVT-T:ITCC blend. The results indicate that to improve the PTV-derivatives photovoltaic properties by suppressing the energetic disorder is a promising way to realize low-cost IOPV cells.

Achieving Small Non-Radiative Energy Loss Through Synergically Non-Fullerene Electron Acceptor Selection and Side Chain Engineering in Benzo[1,2-b:4,5-b']difuran Polymer-Based Organic Solar Cells

Non-radiative recombination loss (ΔEnon-rad) has become the main limiting factor for the power conversion efficiency (PCE) of organic solar cell (OSC). Herein, two benzo[1,2-b:4,5-b']difuran (BDF) polymers (P-FT and P-FP) in...

Nonperturbative effects on radiative energy loss of heavy quarks

The radiative energy loss of fast partons traveling through the quark-gluon plasma (QGP) is commonly studied within perturbative QCD (pQCD). Nonperturbative (NP) effects, which are expected to become important near the critical temperature, have been much less investigated. Here, we utilize a recently developed T -matrix approach to incorporate NP effects for gluon emission off heavy quarks propagating through the QGP. We set up four cases that contain, starting from a Born diagram calculation with color- Coulomb interaction, an increasing level of NP components, by subsequently including (remnants of ) confining interactions, resummation in the heavy-light scattering amplitude, and off-shell spectral functions for both heavy and light partons. For each case we compute the power spectra of the emitted gluons, heavy-quark transport coefficients (drag and transverse-momentum broadening, $$ \hat{q} $$ q ̂ ), and the path-length dependent energy loss within a “QGP brick” at fixed temperature. Investigating the differences in these quantities between the four cases illustrates how NP mechanisms affect gluon radiation processes. While the baseline perturbative processes experience a strong suppression of soft radiation due to thermal masses of the emitted gluons, confining interactions, ladder resummations and broad spectral functions (re-)generate a large enhancement toward low momenta and low temperatures. For example, for a 10 GeV charm quark at 200 MeV temperature, they enhance the transport coefficients by up to a factor of 10, while the results smoothly converge to perturbative results at sufficiently hard scales.