Physical Review Letters 132, 191902 (2024) We report the measurement of the inclusive cross sections for
$e^+e^-$$\rightarrow$nOCH (where nOCH denotes non-open charm hadrons) with
improved precision ...at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV.
We observe three resonances: $\mathcal R(3760)$, $\mathcal R(3780)$, and
$\mathcal R(3810)$ with significances of $8.1\sigma$, $13.7\sigma$, and
$8.8\sigma$, respectively. The $\mathcal R(3810)$ state is observed for the
first time, while the $\mathcal R(3760)$ and $\mathcal R(3780)$ states are
observed for the first time in the nOCH cross sections. Two sets of resonance
parameters describe the energy-dependent line shape of the cross sections well.
In set I set II, the $\mathcal R(3810)$ state has mass $(3805.7 \pm 1.1 \pm
2.7)$ $(3805.7 \pm 1.1 \pm 2.7)$ MeV/$c^2$, total width $(11.6 \pm 2.9 \pm
1.9)$ $(11.5 \pm 2.8 \pm 1.9)$ MeV, and an electronic width multiplied by the
nOCH decay branching fraction of $(10.9\pm 3.8\pm 2.5)$ $(11.0\pm 3.4\pm
2.5)$ eV. In addition, we measure the branching fractions ${\mathcal
B}{\mathcal R}(3760)$$\rightarrow$nOCH$=(25.2 \pm 16.1 \pm 30.4)\% (6.4 \pm
4.8 \pm 7.7)\%$ and ${\mathcal B}\mathcal R(3780)$$\rightarrow$nOCH$=(12.3
\pm 6.6 \pm 8.3)\% (10.4 \pm 4.8 \pm 7.0)\%$ for the first time. The
$\mathcal R(3760)$ state can be interpreted as an open-charm (OC) molecular
state, but containing a simple four-quark state component. The $\mathcal
R(3810)$ state can be interpreted as a hadrocharmonium state.
The natural contamination deposited on the surface of insulators after a period of on-line operation. And under certain weather condition, flashover may occur on the surface of insulators. This paper ...analysed the process of pollution flashover and summarized the characteristics of the pollution flashover accidents. Then an early-warning defense platform for power system accidents caused by pollution flashover is developed. Non-electrical information, such as weather information and other external environmental information, is taken into consideration in this platform. A flashover probability assessment framework is given by combining the static information with the non-electrical information. The static information here means the line data, the insulator string data, etc. So the flashover probability can be calculated dynamically with the change of time, location and surroundings. The result can be used to amend fault list and provide initial fault set for power system safety and stability analysis.
The first observation of the decays $J\!/\!\psi \rightarrow \bar{p}
\Sigma^{+} K_{S}^{0}$ and $J\!/\!\psi \rightarrow p \bar{\Sigma}^{-} K_{S}^{0}$
is reported using $(10087\pm44)\times10^{6}$ ...$J\!/\!\psi$ events recorded by
the BESIII detector at the BEPCII storage ring. The branching fractions of each
channel are determined to be $\mathcal{B}(J\!/\!\psi \rightarrow \bar{p}
\Sigma^{+} K_{S}^{0})=(1.361 \pm 0.006 \pm 0.025) \times 10^{-4}$ and
$\mathcal{B}(J\!/\!\psi \rightarrow p \bar{\Sigma}^{-} K_{S}^{0})=(1.352 \pm
0.006 \pm 0.025) \times 10^{-4}$. The combined result is
$\mathcal{B}(J\!/\!\psi \rightarrow \bar{p} \Sigma^{+} K_{S}^{0} +c.c.)=(2.725
\pm 0.009 \pm 0.050) \times 10^{-4}$, where the first uncertainty is
statistical and the second systematic. The results presented are in good
agreement with the branching fractions of the isospin partner decay $J\!/\!\psi
\rightarrow p K^- \bar\Sigma^0 + c.c.$.
The Pd-La/spinel catalyst for the preparation of 2,6-diisopropylaniline (2,6-DIPA) by gas-phase amination of 2,6-diisopropylphenol (2,6-DIPP) has been studied. The catalysts before and after reaction ...were characterized by BET, XRD, differential thermal analysis (DTA)-thermo gravimetric analysis (TGA), FTIR, and NH
3-TPD techniques. The DTA study results show two kinds of coke deposited on the metal and support of Pd-La/spinel catalyst, and they are combusted at about 242 and 324
°C, respectively. The XRD and FTIR spectra of the Pd-La/spinel catalyst show that the coke contains the aromatic and aliphatic rings, alkyl groups, polynuclear aromatic system, hydroxyl groups, and amine groups. The reason for catalyst deactivation can be expressed as follows: coke formed on palladium metals may move from metal to the interface or boundaries of metal-support and acid sites of the support where further dehydrogenation and polymerization are occurring. The H
2 plays a key role in retarding coke formation, but must be in suitable amount to get relatively high selectivity. The rare earth promoter La not only promotes the activity and selectivity by retaining Pd species in the metallic state, but also decreases the formation of carbon by neutralizing the strong acid sites on the catalyst.
We report a study of the processes of e^{+}e^{-}→K^{+}D_{s}^{-}D^{*0} and K^{+}D_{s}^{*-}D^{0} based on e^{+}e^{-} annihilation samples collected with the BESIII detector operating at BEPCII at five ...center-of-mass energies ranging from 4.628 to 4.698 GeV with a total integrated luminosity of 3.7 fb^{-1}. An excess of events over the known contributions of the conventional charmed mesons is observed near the D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0} mass thresholds in the K^{+} recoil-mass spectrum for events collected at sqrts=4.681 GeV. The structure matches a mass-dependent-width Breit-Wigner line shape, whose pole mass and width are determined as (3982.5_{-2.6}^{+1.8}±2.1) MeV/c^{2} and (12.8_{-4.4}^{+5.3}±3.0) MeV, respectively. The first uncertainties are statistical and the second are systematic. The significance of the resonance hypothesis is estimated to be 5.3 σ over the contributions only from the conventional charmed mesons. This is the first candidate for a charged hidden-charm tetraquark with strangeness, decaying into D_{s}^{-}D^{*0} and D_{s}^{*-}D^{0}. However, the properties of the excess need further exploration with more statistics.
Phys. Rev. Lett. 132, 151901 (2024) Using a sample of $(10087\pm44)\times 10^6$ $J/\psi$ events, which is about
45 times larger than that was previously analyzed, a further investigation on
the ...$J/\psi\rightarrow \gamma 3(\pi^+\pi^-)$ decay is performed. A significant
distortion at 1.84 GeV/$c^2$ in the line-shape of the $3(\pi^+\pi^-)$ invariant
mass spectrum is observed for the first time, which could be resolved by two
overlapping resonant structures, $X(1840)$ and $X(1880)$. The new state
$X(1880)$ is observed with a statistical significance larger than $10\sigma$.
The mass and width of $X(1880)$ are determined to be $1882.1\pm1.7\pm0.7$
MeV/$c^2$ and $30.7\pm5.5 \pm2.4$ MeV, respectively, which indicates the
existence of a $p\bar{p}$ bound state.
Two Hg(II) halide complexes, Hg2Cl4(TPA)2 (1) and HgBr2(TPA) (2) (TPA=tris(2-pyridyl)amine) have been synthesized. X-ray diffraction analyses reveal that 1 is binuclear, whereas, 2 is mononuclear. ...The binuclear structure of 1 is unsymmetrical: one Hg(II) atom is octahedrally coordinated, with the other Hg(II) tetrahedrally coordinated. Hg(II) atom in 2 has a distorted tetrahedral coordination environment. The coordination moieties of complexes 1 and 2 are connected to give 2D and 1D structures, respectively, by weak intermolecular interactions, namely, the multiple π–π interactions between the TPA pyridyl rings in complex 1, and the intermolecular Hg(II)⋯Br interactions in complex 2. 1H NMR, IR, and Raman results are discussed with reference to the crystal structures.
Phys. Rev. D 108, 092011 (2023) Based on $(27.08\pm 0.14)\times10^{8}$ $\psi(3686)$ events collected with the
BESIII detector operating at the BEPCII collider, the
...$\psi(3686)\to\Sigma^{+}\bar{\Sigma}^{-}\omega$ and
$\Sigma^{+}\bar{\Sigma}^{-}\phi$ decays are observed for the first time with
statistical significances of 13.8$\sigma$ and 7.6$\sigma$, respectively. The
corresponding branching fractions are measured to be
$\mathcal{B}(\psi(3686)\to\Sigma^{+}\bar{\Sigma}^{-}\omega)=(1.90 \pm 0.18 \pm
0.21) \times 10^{-5}$ and
$\mathcal{B}(\psi(3686)\to\Sigma^{+}\bar{\Sigma}^{-}\phi)=(2.96 \pm 0.54 \pm
0.41) \times 10^{-6}$, where the first uncertainties are statistical and the
second systematic.
The utility of interstitial water concentrations of metals and simultaneously extracted metals/acid-volatile sulfide differences (SEM-AVS) in two seasons were investigated to explain the biological ...availability of zinc in sediments to benthic organisms exposed in the laboratory. The amphipod Grandidierella japonica was exposed, in 10-day acute toxicity tests, to clean sediment spiked with zinc to obtain nominal treatments ranging from 0.25 to 74.4 μmol g^sup -1^ dry weight with respect to the molar difference between SEM^sub Zn^ and AVS. When the molar difference between SEM^sub Zn^ and AVS (i.e., SEM-AVS) was <0 μmol g^sup -1^, the concentration of zinc in the sediment interstitial water was low and few adverse effects were observed for any of the biological endpoints measured. Conversely, when SEM^sub Zn^-AVS exceeded 0 μmol g^sup -1^, the concentration of zinc in the interstitial water and amphipod mortality increased. These data compare favorably with observations made in short-term exposures and thus support the use of AVS as a normalization phase for predicting toxicity in metal-contaminated sediments in different season.PUBLICATION ABSTRACT
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