Spectroscopic observation of Feshbach resonances in the tellurium dimer anion.

We report on the high-resolution photodetachment spectroscopy of the cryogenically cooled anionic tellurium dimer (Te2-). The high-resolution resonant photoelectron spectrum yields an accurate electron affinity of 16 689.7(92) cm-1 or 2.0693(11) eV for Te2. Two resonant states of Te2- anions have been identified, positioned at 1092(17) cm-1 below and 250(11) cm-1 above the photodetachment threshold, respectively. The spectra of resonant two-photon detachment (R2PD) and autodetachment from a specific vibrational level through a Feshbach resonance exhibit notable non-Franck-Condon behaviors. Using the spectroscopic data from the current experiment, the equilibrium bond distances and spectroscopic constants of the ground state and two electronically excited states of Te2- were determined.

The unusual quadruple bonding of nitrogen in ThN.

Nitrogen has five valence electrons and can form a maximum of three shared electron-pair bonds to complete its octet, which suggests that its maximum bond order is three. With a joint anion photoelectron spectroscopy and quantum chemistry investigation, we report herein that nitrogen presents a quadruple bonding interaction with thorium in ThN. The quadruple Th≣N bond consists of two electron-sharing Th-N π bonds formed between the Th-6dxz/6dyz and N 2px/2py orbitals, one dative Th←N σ bond and one weak Th←N σ bonding interaction formed between Th-6dz2 and N 2s/2pz orbitals. The ThC molecule has also been investigated and proven to have a similar bonding pattern as ThN. Nonetheless, due to one singly occupied σ-bond, ThC is assigned a bond order of 3.5. Moreover, ThC has a longer bond length as well as a lower vibrational frequency in comparison with ThN.

Electron affinity of atomic scandium and yttrium and excited states of their negative ions.

The latest experimental electron affinity (EA) values of atomic scandium and yttrium were 0.189(20) and 0.308(12) eV as reported by Feigerle et al. in 1981. The measurement accuracy of these was far lower than that of other transition elements, and no conclusive result had been made on the excited states of their negative ions. In the current work, we report more accurate EA values of Sc and Y and the electronic structure of their negative ions using the slow-electron velocity-map imaging method. The EA values of Sc and Y are determined to be 0.179 378(22) and 0.311 29(22) eV, respectively. The ground state of Sc- is identified as 3d4s24p 1D2, and the ground state is 4d5s25p 1D2 for Y-. Furthermore, several excited states of Sc- and Y- are observed: Sc- (3D1) and Y- (3D1, 3D2, 3D3, 3F2, and 3F3), and their energy levels are determined to be 1131.8(28), 1210.0(13), 1362.3(30), 1467.7(26), 1747(16), and 1987(33) cm-1, respectively.

A case report of 4-day-old neonate infected with Omicron variant BA.5.1.3 / 中国热带医学

@#Abstract: Objective　To understand the clinical manifestations, symptoms, treatment and recovery of neonates infected with Omicron variant (BA.5.1.3) of SARS-CoV-2, and provide a certain reference for subsequent diagnosis and treatment of related diseases. Methods　The clinical manifestations, epidemiology, auxiliary examinations, and treatment processes of the neonate aged 4-day-old who was community-acquired infection of variant BA.5.1.3 in Sanya was retrospectively analyzed. Results　The neonate's mother was identified as a close contact with patients with coronavirus disease 2019 (COVID-19) one hour before delivery, and tested positive for nucleic acid within 24 hours after delivery. But her breast milk, amniotic fluid, placenta, and umbilical cord were not detected for nucleic acid test after delivery. The nucleic acid test of the neonate was negative within 24 hours after birth. Then he was transferred to the hotel for isolation. Before the transfer, the mother and baby stayed in the same room and ate breast milk but the mother did not wear any mask. The neonate didn't have nucleic acid test on the second and third days of his life, and the nucleic acid test of the neonate was positive on the fourth day, negative on the fifth day, and positive on the sixth day. Then he was transferred to the designated hospital of COVID-19 for treatment. The neonate had no cough, no fever, yellow skin, abdominal distension, general breast feeding, and good reaction. On admission, the laboratory examination showed that blood routine examination and electrolyte were normal, and the myocardial enzyme and liver and kidney functions were normal. The bilirubin was significantly increased (449.3 μmol/L). The nucleic acid test of the neonate was positive and his chest imaging results were normal. The treatment measures were mainly isolation, feeding, blue light fading, close monitoring of vital signs, and antiviral drugs were administered. Jaundice subsided and abdominal distension was relieved after 6 d of treatment, and the treatment process was smooth without complications. Conclusions　The results suggest that the neonates are susceptible to Omicron variant BA.5.1.3 and prone to aggregation. The evidence of vertical transmission is insufficient and the clinical symptoms of neonates infected with Omicron variant BA.5.1.3 are mid, with no involvement of organ damage of the heart, liver, kidney, brain, and other organs.

Molecular manipulations of miR398 increase rice grain yield under different conditions.

Rice miR398 targets two stress-tolerant genes, CSD1-2 (Cu/Zn Superoxide Dismutases1-2) and CCS (copper chaperone of CSD), which usually boost plants' tolerance by inhibiting growth. So, how to accurately regulate the activities of miR398 targets and thus make rice better able to adapt to different conditions has great significances in producing rice yields under the current circumstances of shrinking arable lands resulting from global urbanization and increasing salty soil caused by irrigation. Through controlling the expressions of miR398 in different levels, we found down-regulated expression of miR398 targets can promote growth under good growth conditions while up-regulated expressions of the targets can help rice tolerate salt. In this study, we over-expressed miR398 highly, moderately, and lowly, then three concomitantly inverse levels of its targets' expression were obtained. Under normal growth conditions, the transgenic lines with low and moderate levels of over-expressions of miR398 could increase grain yields 14.5% and 7.3%, respectively, although no transgenic lines could survive well under salty conditions simulating real saline-alkali soil. Using short tandem target mimic (STTM) technology to silence miR398 highly, moderately, and lowly respectively, also three inverse levels of its targets' expression were obtained. All three transgenic lines exhibited good agronomic performances under salt stress in inverse to their degrees of STTM, but their growth was inhibited differently under normal conditions. Altogether, we suggest that flexibly manipulating the expression of miR398 is an ideal strategy to help rice survive better and achieve optimized yields under specific conditions.

Probing Isomerization Dynamics via a Dipole-Bound State.

The observation of molecular isomerization dynamics is a long-standing goal in physical chemistry. The loosely bound electron in a dipole-bound state (DBS) can be a messenger for probing the isomerization of the neutral core. Here we study the isomerization dynamics of the salt dimer (NaCl)2 from linear to rhombic via a DBS using cryogenic photoelectron spectroscopy in combination with ab initio calculations. Although the energy level of the DBS is below the electron affinity of the linear (NaCl)2, (NaCl)2- in its DBS can autodetach due to the linear-to-rhombic isomerization. (NaCl)2- in the ground DBS has a relatively long lifetime of a few nanoseconds due to the quantum tunneling through a potential barrier during the transformation from linear to rhombic. In contrast, the vibrationally excited DBS has a much shorter lifetime on the order of picoseconds. The energy distribution of autodetachment electrons has an unexpected characteristic of the thermionic emission.

Electron affinity of tantalum and excited states of its anion.

The tantalum anion has the most complicated photoelectron spectrum among all atomic anions of transition elements, which was the main obstacle to accurately measure its electron affinity via the generic method. The latest experimental value of the electron affinity of Ta was 0.323(12) eV, reported by Feigerle et al. [J. Chem. Phys. 74, 1580 (1981)]. In the present work, we report the high-resolution photoelectron spectroscopy of Ta- via the slow-electron velocity-map imaging method combined with a cryogenic ion trap. The electron affinity of Ta was measured to be 2652.38(17) cm-1 or 0.328 859(23) eV. Three excited states 5D1, 3P0, and 5D2 of Ta- were observed, and their energy levels were determined to be 1169.64(17) cm-1 for 5D1, 1735.9(10) cm-1 for 3P0, and 2320.1(20) cm-1 for 5D2 above the ground state 5D0, respectively.

Structural Versatility and Energy Difference of Salt-Water Complex NaCl(H2O) Encoded in Cryogenic Photoelectron Spectroscopy.

A weakly bound complex usually has multiple structural isomers with small energy differences. The sophisticated ab initio calculations are the main workhorse for providing theoretical results of different isomers. In contrast, the experimental determination of the energy difference is very rare. We report the energy-difference measurement of a model complex: salt-water complex NaCl(H2O). We measured the energy difference among the structural isomers of the negatively charged NaCl(H2O) complex and the neutral counterpart using cryogenic photoelectron spectroscopy. The temperature-dependent photoelectron spectra (15-300 K) revealed that the negatively charged NaCl(H2O) and the neutral counterpart both have three isomers. The two higher-lying isomers are 186(22) and 481(48) cm-1, respectively, above the most stable isomer for the negatively charged and 123(10) and 1821(24) cm-1 for the neutral. These results provide a benchmark for the development of theoretic methods of weakly bound complexes. The experimental technique demonstrated here can be employed to investigate other weakly bound complexes with multiple isomers.

Association of Parental Famine Exposure With Offspring Depression and Cognition Function.

Background: The effect of early exposure to famine on depression and cognition in adulthood has been shown, but the intergenerational association of famine remain to be explored. This study focused on exploring the association of parental famine exposure with depression and cognition in the offspring. Methods: Based on the Chinese Family Panel Studies database, which is a longitudinal survey, we included 5,150 individuals born between 1959 and 1961 and divided them into fetal-exposed, infancy-exposed (birth year = 1957-1958), school-age-exposed (birth year = 1949-1956), adolescent-exposed (birth year = 1946-1948), and unexposed groups. We used one-way analysis of variance, multiple linear regression, and one follow-up measurement to analyze the association between parental famine exposure and offspring depression and cognitive function. Results: Compared with the unexposed group, the correlations between parental famine exposure during fetal period and their cognitive function (mother: ß = -1.614, 95% CI: -2.535, -0.693; p = 0.001; father: ß = -2.153, 95% CI: -3.104, -1.202, p < 0.001) were significant. For the offspring, there was a negative correlation between famine exposure of fathers during the fetal period and depression in their offspring (ß = -0.477, 95% CI: -0.907, -0.047; p = 0.030). There was a negative correlation between maternal famine exposure during the infant and adolescent period and cognitive function in the offspring (math test: ß = -0.730, 95% CI: -1.307, -0.153; p = 0.013; word test: ß = -2.346, 95% CI: -4.067, -0.625; p = 0.008). Limitations: Not all variables related to depression and cognition function were included in the CFPS database, and the other unknown or unmeasured confounders may explain our results.

Observation of an Excited Dipole-Bound State in a Diatomic Anion.

We report the observation of σ-type and π-type excited dipole-bound states (DBSs) in cryogenically cooled potassium iodide (KI) anions for the first time. Two DBSs were observed 39.7(10) meV and 5.0(12) meV below the photodetachment threshold via the resonant two-photon detachment. The different photoelectron angular distributions and binding energies suggest that the two DBSs are of different types. The existence of one σ-type and one π-type DBS in the KI anion was also supported by the high-level ab initio theoretical calculations. The excellent agreement between experimental and theoretical results confirms the prediction that a dipolar molecule with a large enough dipole moment can have an excited DBS.

Dipole-bound and valence excited states of AuF anions via resonant photoelectron spectroscopy.

Gold fluoride is a very unique species. In this work, we reported the resonant photodetachment spectra of cryogenically cooled AuF- via the slow-electron velocity-map imaging method. We determined the electron affinity of AuF to be 17 976(8) cm-1 or 2.2287(10) eV. We observed a dipole-bound state with a binding energy of 24(8) cm-1, a valence excited state with a binding energy of 1222(11) cm-1, and a resonant state with an energy of 814(12) cm-1 above the photodetachment threshold. An unusual vibrational transition with Δn = -3 was observed in the autodetachment from the dipole-bound state. Moreover, two excited states of neutral AuF were recognized for the first time, located at 13 720(78) cm-1 and 16 188(44) cm-1 above the AuF ground state.

The Rice miR396-GRF-GIF-SWI/SNF Module: A Player in GA Signaling.

Rice Growth-Regulating Factors (GRFs) were originally identified to be gibberellin (GA)-induced, but the nature of GA induction has remained unknown because most reports thereafter focused on revealing their roles in growth-promoting activities. GRFs have the WRC (Trp, Arg, Cys) domain to target DNA and contain the QLQ (Gln, Leu, Gln) domain to interact with GRF-Interacting Factor (GIF), which recruits ATP-dependent DNA translocase Switch/Sucrose Non-fermenting (SWI/SNF) for chromatin remodeling. Both GRFs and GIFs exhibit transcriptional activities but GIFs lack a DNA-binding domain. So, GRFs act like a navigator in the GRF-GIF-SWI/SNF complex, determining when and where the complex should work on. The levels of most rice GRFs can be sensitively regulated by miR396, which responds to many developmental and environmental factors. Recent clues from several studies highlight the original question of how GRFs participate in GA signaling. DELLA (contain DELLA motif) protein plays dual roles in controlling the level of GRFs by regulating the level of miR396 and interacting with GRFs. Here we address the question of why this complex plays an essential role in controlling plant growth focusing on the action of GA signaling pivot, DELLA.

Coordination between GROWTH-REGULATING FACTOR1 and GRF-INTERACTING FACTOR1 plays a key role in regulating leaf growth in rice.

BACKGROUND: The interactions between Growth-regulating factors (GRFs) and GRF-Interacting Factors (GIFs) have been well demonstrated but it remains unclear whether different combinations of GRF and GIF play distinctive roles in the pathway downstream of the complex. RESULTS: Here we showed that OsGRF1 and OsGIF1 synergistically regulate leaf growth in rice. The expression of OsGIF1 emerged in all tissues with much higher level while that of OsGRF1 appeared preferentially only in the stem tips containing shoot apical meristem (SAM) and younger leaves containing leaf primordium. Overexpression of an OsmiR396-resistant version of mOsGRF1 resulted in expanded leaves due to increased cell proliferation while knockdown of OsGRF1 displayed an opposite phenotype. Overexpression of OsGIF1 did not exhibit new phenotype while knockdown lines displayed pleiotropic growth defects including shrunken leaves. The crossed lines of mOsGRF1 overexpression and OsGIF1 knockdown still exhibited shrunk leaves, indicating that OsGIF1 is indispensable in leaf growth regulated by OsGRF1. The expression of OsGRF1 could be upregulated by gibberellins (GAs) and downregulated by various stresses while that of OsGIF1 could not. CONCLUSION: Our results suggest that OsGIF1 is in an excessive expression in various tissues and play roles in various aspects of growth while OsGRF1 may specifically involve in leaf growth through titrating OsGIF1. Both internal and external conditions impacting leaf growth are likely via way of regulating the expression of OsGRF1.

Accurate electron affinity of Ga and fine structures of its anions.

We report the high-resolution photoelectron spectra of negative gallium anions obtained via the slow-electron velocity-map imaging method. The electron affinity of Ga is determined to be 2429.07(12) cm-1 or 0.301 166(14) eV. The fine structures of Ga are well resolved: 187.31(22) cm-1 or 23.223(27) meV for 3P1 and 502.70(28) cm-1 or 62.327(35) meV for 3P2 above the ground state 3P0, respectively. The photoelectron angular distribution for photodetachment from Ga-(4s24p2 3P0) to Ga(4s25s 2S1/2) is measured. An unexpected perpendicular distribution instead of an isotropic distribution is observed, which is due to a resonance near 3.3780 eV.

Measurement of electron affinity of iridium atom and photoelectron angular distributions of iridium anion.

The latest electron affinity value of an iridium atom is 1.564 36(15) eV, determined via a method based on the Wigner threshold law by Bilodeau and co-workers. However, they observed a significant deviation from the Wigner threshold law in the threshold photodetachment experiment. To address this dilemma, we conducted high-resolution photoelectron spectroscopy of Ir- via the slow-electron velocity-map imaging method in combination with an ion trap. The electron affinity of Ir was measured to be 12 614.97(9) cm-1 or 1.564 057(11) eV. We find that the Wigner threshold law is still valid for the threshold photodetachment of Ir- through a p-wave fitting of the photodetachment channel Ir-5d86s23F4→Ir5d86sb4F9/2. The photoelectron angular distributions of photodetachment channels Ir-5d86s23F4→Ir5d76s2a4F9/2 and Ir-5d86s23F4→Ir5d86sb4F9/2 were also investigated. The behavior of anisotropy parameter ß indicates a strong interaction between the two channels. Moreover, the energy level 3P2 of Ir-, which was not observed in the previous works, was experimentally determined to be 4163.24(16) cm-1 above the ground state.

SLENDER RICE1 and Oryza sativa INDETERMINATE DOMAIN2 Regulating OsmiR396 Are Involved in Stem Elongation.

GAs play key roles in controlling cell proliferation through the GIBBERELLIN INSENSITIVE DWARF1/DELLA-mediated pathway. However, how DELLA proteins affect downstream pathways is not well understood. Therefore, discovering the signaling events downstream of DELLAs is key to better understanding the roles of GAs in plant development. Here, we discovered that miR396 is regulated by SLENDER RICE1 (SLR1) in controlling cell proliferation. The positive response of rice (Oryza sativa) GROWTH-REGULATING FACTORs (OsGRFs) to GAs was found to be caused by a negative response of miR396 to GAs. miR396 acts downstream of SLR1 and upstream of GA-induced cell-cycle genes. Rice INDETERMINATE DOMAIN2 (OsIDD2) directly binds the promoter of OsmiR396a and can interact with SLR1 in vivo and in vitro. Rice lines overexpressing miR396a (miR396OE) or OsIDD2 (OsIDD2OE) displayed dwarfism resulting from higher abundance of miR396 RNA. However, the stem elongation of OsIDD2OE plants could be significantly stimulated by applying exogenous GA3, while that of miR396OE plants could not. Rice with OsIDD2 knocked down by RNA interference showed a slr1-like phenotype, in which the expression of miR396 was inhibited while its targets were enhanced. The protein levels of OsIDD2 were unaffected by GA in wild-type and OsIDD2OE plants, implying that OsIDD2 promotes the expression of miR396 and likely requires the coactivator of SLR1. Taken together, these results provided a close link between SLR1/OsIDD2 and GRFs via a negative regulator, miR396, and thus highlighted a molecular mechanism of GA-mediated cell proliferation in rice.

Candidate for Laser Cooling of a Negative Ion: High-Resolution Photoelectron Imaging of Th

Laser cooling is a well-established technique for the creation of ensembles of ultracold neutral atoms or positive ions. This ability has opened many exciting new research fields over the past 40 years. However, no negatively charged ions have been directly laser cooled because a cycling transition is very rare in atomic anions. Efforts of more than a decade currently have La^{-} as the most promising candidate. We report on experimental and theoretical studies supporting Th^{-} as a new promising candidate for laser cooling. The measured and calculated electron affinities of Th are, respectively, 4901.35(48) cm^{-1} and 4832 cm^{-1}, or 0.607 690(60) and 0.599 eV, almost a factor of 2 larger than the previous theoretical value of 0.368 eV. The ground state of Th^{-} is determined to be 6d^{3}7s^{2} ^{4}F_{3/2}^{e} rather than 6d^{2}7s^{2}7p ^{4}G_{5/2}^{o}. The consequence of this is that there are several strong electric dipole transitions between the bound levels arising from configurations 6d^{3}7s^{2} and 6d^{2}7s^{2}7p in Th^{-}. The potential laser-cooling transition is ^{2}S_{1/2}^{o}↔^{4}F_{3/2}^{e} with a wavelength of 2.6 µm. The zero nuclear spin and hence lack of hyperfine structure in Th^{-} reduces the potential complications in laser cooling as encountered in La^{-}, making Th^{-} a new and exciting candidate for laser cooling.

Effect of purslane (Portulaca oleracea L.) extract on anti-browning of fresh-cut potato slices during storage.

Enzymatic browning is a crucial reaction affecting the quality of fresh-cut fruit and vegetables. Purslane is an edible Chinese folk medicine with extensive distribution and containing a lot of polyphenols and alkaloids. However, little research on its' anti-browning effect on fresh-cut food was reported. In this study, the effectiveness of 0.05% (w/w) purslane aqueous extract treatment efficiently inhibited the activities of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia-lyase (PAL), the membrane integrity was effectively maintained, and malondialdehyde (MDA) content increases was retarded during whole storage period at 4 °C. Oddly, the higher purslane extract concentration, the lower endogenesis phenolic content. Additionally, thirty polyphenols and fifty-six alkaloids were found in purslane aqueous extract by LC-MS/MS. All results suggest that purslane aqueous extract is a promising nutritive anti-browning agent for fresh-cut potato.

Ground-State Pd Anions React with H2 Much Faster than the Excited Pd Anions.

Recent advances in experimental techniques have made it relatively easy to prepare reactant cations in well-defined states of electronic excitation. Extensive studies on the role of excited states in the cation-neutral reactions have contributed significantly to our understanding of reaction kinetics and dynamics. The excited states are often more reactive than the ground state. However, the reactions involving the excited atomic anion are very rare because the negative ions usually have no bound excited states. In the present work, we report the state-specific reaction of Pd anions with H2. Surprisingly, we observed that the ground-state Pd anions react with H2 10 times faster than the excited Pd anions. The high-level calculations show that the difference is due to the reaction barrier.