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The Landau-Zener formula is a semiclassical model describing nonadiabatic transitions, but its range of validity in approaching the adiabatic regime had not been verified. The authors investigate electron transfer reactions in a series of mixed-valence complexes spanning the nonadiabatic throughout the adiabatic limit, and show that the model is valid in a broader range of conditions than previously expected.

The nervous system of the silkworm is vital for the development of organisms. It achieves and maintains normal life activities by regulating the function of the organs and all kinds of physiological processes in the silkworm. BmApontic (BmApt), as an important bZIP transcription factor, is required for the formation of pigmentation in the silkworm. However, the function of BmApt in the development of the nervous system of the silkworm remains unclear. Here, we showed that amino acid sequence of BmApt was evolutionarily conserved in its Myb/SANT motif and basic DNA binding domain. BmApt was expressed in the nervous system at the embryonic stage. Knockdown of Bmapt by RNA interference resulted in abnormal development of axons. Moreover, the expression of BmnetrinA, BmnetrinB and Bmfrazzled was decreased in the Bmapt knockdown embryos. These results demonstrate that BmApt controls neurodevelopment by activating the expression of Bmnetrin and Bmfrazzled.

To broaden the application of magnesium oxychloride cement (MOC) in thermal insulation materials, lightly burned magnesia powder and magnesium chloride hexahydrate were used as the main raw materials of cement and a chemical foaming method was used to prepare a magnesium oxychloride cement foam concrete (MOCFC) with fast hardness and early strength. By changing the molar ratio (M) of the MOCFC and adding different dosages of hydrogen peroxide (H₂O₂), fly ash (FA), potassium dihydrogen phosphate (KDP) and other admixtures, while measuring and observing the compressive strength and flexural strength at 3, 7, and 28 days, the thermal conductivity, dry apparent density, volume water absorption, softening coefficient, and other parameters, combined with its hydration phase composition and microscopic appearance, the effect of the molar ratio and the admixtures on the properties of MOCFC were studied. The results show that with an increase in the molar ratio and the dosage of H₂O₂, FA and KDP, the internal pore structure of the slurry changes significantly, which affects its mechanical properties, water resistance, and thermal insulation performance.

We design a novel negative curvature fiber (NCF) to support terahertz orbital angular momentum (OAM) modes. Numerical models are constructed to evaluate the transmission performances of vector modes in the frequency range of 0.40–0.80 THz. The designed fiber made from only one kind of heat-resistance resin (HTL) material can support 50–52 OAM modes with large effective index differences above 10−4 and low confinement loss (in the level of 10−15 dB/cm). Some other significant characteristics of the designed NCF including waveguide dispersion, OAM purity, and effective mode field area (Aeff), are also calculated and analyzed with their effects and applications on terahertz OAM guidance. The optimized absolute value of dispersion is between 0.33 and 0.8 ps/(THz × cm) in the range of 0.45–0.75 THz. The high mode purity (85%−95%) in the range of 0.60–0.80 THz further promotes the mode division multiplexing in OAM fiber. The proposed NCF can offer great potential in high-capacity terahertz communication based on OAM multiplexing.

Summary: Studies of intermolecular interactions enhance our knowledge of chemistry across molecular and supramolecular levels. Here, we show that host-guest quadrupolar interaction has a profound influence on the molecular system. With covalently bonded dimolybdenum complex units as the electron donor (D) and acceptor (A) and a thienylene group (C4H2S) as the bridge (B), the mixed-valence D-B-A complexes are shaped with clefts in the middle of the molecule. Interestingly, in aromatic solvents, the D-A electronic coupling constants (Hab) and electron transfer rates (ket) are dramatically reduced. Theoretical computations indicate that an aromatic molecule is encapsulated in the cleft of the D-B-A array; quadrupole-quadrupole interaction between the guest molecule and the C4H2S bridge evokes a charge redistribution, which increases the HOMO-LUMO energy gap, intervening in the through-bond electron transfer. These results demonstrate that a supramolecular system is unified underlying the characteristics of the assembled molecules through constitutional, electronic, and energetic complementarities. : Supramolecular Chemistry; Computational Molecular Modelling; Molecular Physics Subject Areas: Supramolecular Chemistry, Computational Molecular Modelling, Molecular Physics

Thermal electron transfer across hydrogen bond remains largely unexplored. Here the authors demonstrate that electron self-exchange through hydrogen bonds is highly efficient and can proceed either via the known proton-coupled pathway or an overlooked proton-uncoupled pathway

A tunable graphene terahertz metamaterial absorber is designed by treating a monolayer continuous dumbbell-shaped structure graphene layer, which can simultaneously realize the narrow bandwidth and dual-band absorption with transverse magnetic (TM) polarization and wide incident angle operation. Two pronounced absorption peaks are caused by the novel toroidal dipole phenomenon and magnetic plasmon polariton. By optimizing the geometry parameters, the relative narrow bandwidths of the two absorption peaks are 26.4 and 23.5 GHz at frequencies of 0.2242 THz and 0.5302 THz, respectively, with the absorption rate above 99.6%. Since the continuous dumbbell-shaped graphene structure is treated in the absorber, a more convenient way to realize the tuning ability by treating a bias voltage compared to the absorbers with discrete graphene structures. The designed device can work at a wide incident angles (up to 80°) under TM polarization with the absorption above 88% at low frequency. The simulation results are basically in good agreement with the results of the equivalent circuit model. This work offers huge potential applications in terahertz imaging, detecting and sensing, especially in the 6G communication systems.

A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-21530-8

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Using proprietary data on nonperforming loan (NPL) transactions in China, we document that banks conceal NPLs in disposal transactions that are supposed to resolve NPLs. In these transactions, banks provide financing and retain the credit risks and debt collection obligations. Transaction prices contradict underlying credit risks: Despite being delinquent for 4.5 years, the median NPL package is sold at face value with zero haircut. The majority of NPL packages are resold at a premium to banks' non–government-owned borrowers, further supporting the concealment view. Banks under stricter regulation conceal NPLs more and engage in more illicit concealment. NPL-concealing banks increase zombie lending, suggesting that an ineffective resolution exacerbates credit misallocation. Recognizing the hidden NPLs implies the total NPLs in China is two to three times the reported amount. This paper was accepted by Victoria Ivashina, finance. Funding: B. Charoenwong acknowledges financial support from the Singapore Ministry of Education [AcRF Tier 1 Research Grant A-8000760-00-00]. T. Ruan acknowledges financial support from the National University of Singapore (NUS) [Start-Up Grant A-0003870-00-00]. B. Charoenwong and T. Ruan acknowledge financial support from the NUS Business School Financial Database [Grant N-311-000-251-001]. Supplemental Material: The online appendix and data files are available at https://doi.org/10.1287/mnsc.2022.02163. [ABSTRACT FROM AUTHOR]