Unveiling the anchoring and catalytic effect of Co@C3N3 monolayer as a high-performance selenium host material in lithium-selenium batteries: a first-principles study.

Suppressing the shuttle effect of high-order polyselenides is crucial for the development of high-performance host materials in lithium-selenium (Li-Se) batteries. Using first-principles calculations, the feasibility of Co@C3N3 monolayer as selenium cathode host material for Li-Se batteries is systematically evaluated from the aspects of binding energy, charge transfer mechanism, and catalytic effect of polyselenides in the present work. The Co@C3N3 monolayer can effectively prevent the solubilization of high-order polyselenides with large binding energy and charge transfer resulting from the synergistic effect of Li-N and Co-Se bonds. The polyselenides are inclined to adsorb on the surface of Co@C3N3 monolayer instead of interacting with the electrolytes, which effectively inhibits the shuttling of high-order polyselenides and improves cycling stability. The cobalt participation improves the conductivity of C3N3 monolayer, and the semi-metallic characteristics of the Co@C3N3 monolayer are maintained after the adsorption of Li2Sen (n = 1, 2, 4, 6, 8) or Se8 clusters, which is advantageous for the utilization of active selenium material. The crucial catalytic role of the Co@C3N3 monolayer is evaluated by examining the reduction pathway of Se8 and the decomposition barrier of Li2Se, and the results highlight the capability of Co@C3N3 monolayer to enhance the utilization of selenium and promote the transition of Li2Se. Our present work could not only provide valuable insights into the anchoring and catalytic effect of Co@C3N3 monolayer, but also shed light on the future investigation on the high performance C3N3-based host materials for Li-Se batteries.

Theoretical Prediction of Thermoelectric Performance for Layered LaAgOX (X = S, Se) Materials in Consideration of the Four-Phonon and Multiple Carrier Scattering Processes.

Inspired by the experimental achievement of layered LaCuOX (X = S, Se) with superior thermoelectric (TE) performance, the TE properties of Ag-based isomorphic LaAgOX are systemically investigated by the first-principles calculation. The LaAgOS and LaAgOSe are direct semiconductors with wide bandgaps of ≈2.50 and ≈2.35 eV. Essential four-phonon and multiple carrier scattering mechanisms are considered in phonon and electronic transport calculations to improve the accuracy of the figure-of-merit (ZT). The p-type LaAgOX (X = S, Se) shows excellent TE performance on account of the large Seebeck coefficient originated from the band convergency and low thermal conductivity caused by the strong phonon-phonon scattering. Consequently, the optimal ZTs along the out-of-plane direction decrease in the order of n-type LaAgOSe (≈2.88) > p-type LaAgOSe (≈2.50) > p-type LaAgOS (≈2.42) > n-type LaAgOS (≈2.27) at 700 K, and the optimal ZTs of ≈1.16 and ≈1.29 are achieved for p-type LaAgOS and LaAgOSe at the same temperature. The present work would provide a deep insight into the phonon and electronic transport properties of LaAgOX (X = S, Se), but also could shed light on the way for the rational design of state-of-the-art heteroanionic materials for TE application.

[Retracted] MicroRNA­18b acts as an oncogene in gastric cancer by directly targeting Kruppel­like factor 6.

Following the publication of this paper, it was drawn to the Editors' attention by a concerned reader that certain of the cell migration assay data shown in Fig. 2C were strikingly similar to data that had appeared in different form in other articles by different authors. Owing to the fact that the contentious data in the above article had already been published elsewhere, or were already under consideration for publication, prior to its submission to Molecular Medicine Reports, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 19: 1926­1934, 2019; DOI: 10.3892/mmr.2019.9830].

Low-cost pentagonal NiX2 (X = S, Se, and Te) monolayers with strong anisotropy as potential thermoelectric materials.

Pentagonal compounds, as a new family of 2D materials, have recently been extensively studied in the fields of electrocatalysis, photovoltaics, and thermoelectrics. Encouraged by the successful synthesis of pentagonal PdSe2, the thermoelectric properties of low-cost pentagonal NiX2 (X = S, Se, and Te) monolayers are theoretically predicted with the help of first-principles calculations and the semiclassical Boltzmann transport theory. The high dynamic and thermal stabilities of pentagonal NiX2 (X = S, Se, and Te) monolayers are confirmed according to the phonon dispersion spectrums and ab initio molecular dynamics (AIMD) simulations. Indirect semiconductor features with wide bandgaps of 2.44, 2.31, and 1.88 eV at the Heyd-Scuseria-Ernzerhof (HSE06) level are discovered for pentagonal NiS2, NiSe2, and NiTe2 monolayers. Combining the Boltzmann transport equation and deformation potential theory, the Seebeck coefficient, power factor, and thermoelectric figure of merit (ZT) of NiX2 (X = S, Se, and Te) monolayers are evaluated from 300 to 600 K. The strongly anisotropic ZT values are discovered, which are attributed to the significant differences in electrical and thermal transport along the x and y directions. In addition, low lattice thermal conductivities are observed at 600 K for the pentagonal NiTe2 monolayer, accompanying higher ZT values of 1.81 and 1.58 along the x and y directions. The predicted thermoelectric properties indicate that the low-cost pentagonal NiSe2 and NiTe2 monolayers are potential anisotropic thermoelectric materials with high performance.

MicroRNA­18b acts as an oncogene in gastric cancer by directly targeting Kruppel­like factor 6.

Gastric cancer (GC) is the fourth most frequently occurring cancer and the second most common cause of cancer­associated mortality worldwide. An increasing number of studies have reported that microRNAs (miRNAs/miRs) contribute to the regulation of GC development and progression. Therefore, investigation of the miRNAs involved in the development of GC may result in identification of an effective therapeutic target for patients with this malignancy. miR­18b has been reported to be aberrantly expressed in several types of human cancer. However, the expression pattern, biological role and specific functional mechanism of miR­18b in GC remains to be elucidated. In the present study, reverse transcription­quantitative polymerase chain reaction (RT­qPCR) analysis revealed that miR­18b was significantly upregulated in GC tissues and cell lines compared with normal gastric tissues and the human gastric epithelial immortalized cell line GES­1, respectively. High miR­18b expression was significantly associated with lymph node metastasis, invasive depth and the Tumor Node Metastasis stage of patients with GC. Additionally, functional assays indicated that the inhibition of miR­18b attenuated cell proliferation and invasion in GC. Furthermore, Kruppel­like factor (KLF)­6 was identified as a direct target gene of miR­18b in GC, from the results of bioinformatics analysis, a luciferase reporter assay, RT­qPCR and western blot analysis. An inverse association was observed between miR­18b and KLF6 mRNA levels in GC tissues. KLF6 knockdown partially abrogated the effects of miR­18b inhibition on GC cell proliferation and invasion. Therefore, miR­18b/KLF6 targeted therapy may provide a promising treatment for patients with GC.