Structural Characterization and Functional Analysis of Mevalonate Kinase from Tribolium castaneum (Red Flour Beetle).

Mevalonate kinase (MevK) is an important enzyme in the mevalonate pathway that catalyzes the phosphorylation of mevalonate into phosphomevalonate and is involved in juvenile hormone biosynthesis. Herein, we present a structure model of MevK from the red flour beetle Tribolium castaneum (TcMevK), which adopts a compact α/ß conformation that can be divided into two parts: an N-terminal domain and a C-terminal domain. A narrow, deep cavity accommodating the substrate and cofactor was observed at the junction between the two domains of TcMevK. Computational simulation combined with site-directed mutagenesis and biochemical analyses allowed us to define the binding mode of TcMevK to cofactors and substrates. Moreover, TcMevK showed optimal enzyme activity at pH 8.0 and an optimal temperature of 40 °C for mevalonate as the substrate. The expression profiles and RNA interference of TcMevK indicated its critical role in controlling juvenile hormone biosynthesis, as well as its participation in the production of other terpenoids in T. castaneum. These findings improve our understanding of the structural and biochemical features of insect Mevk and provide a structural basis for the design of MevK inhibitors.

Selenophene-Based 2D Ruddlesden-Popper Perovskite Solar Cells with an Efficiency Exceeding 19.

Two-dimensional (2D) Ruddlesden-Popper (RP) perovskites have emerged as attractive candidates for high-performance perovskite solar cells (PSCs) thanks to their superior environmental and structural stability. However, 2D RP PSCs exhibit larger exciton binding energy due to the dielectric mismatch between the organic and inorganic layers, resulting in poorer photovoltaic performance compared to their 3D analogs. Here, we developed a selenophene-based spacer, namely, 2-selenophenemethylammonium (SeMA), for stable and efficient 2D RP PSCs. The 2D perovskite film using methylammonium (MA) as the A-site cation (nominal n = 5) shows excellent film quality with large grain size and a preferred vertical orientation relative to the substrate. Furthermore, we have successfully demonstrated the effectiveness of a predeposition transport layer (PDTL) consisting of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in passivating surface defects of the perovskite film and inducing densification of the upper PCBM electron transport layer. This densification promotes efficient extraction and transport of electrons. The optimized PSCs based on 2D RP perovskite using MA as A-site cation (nominal n = 5) achieved a power conversion efficiency (PCE) of 17.25%, which was further boosted to 19.03% when using formamidinium (FA) as A-site cation. This represents a record PCE of 2D RP PSCs by using the selenophene-based spacer. Moreover, these 2D RP PSCs significantly improve thermal, moisture, and light stability. Our results provide significant implications for the synergistic strategy of developing selenophene-based spacers and device engineering methods for achieving highly efficient and stable 2D RP perovskite solar cells.

Fibulin-2: A potential regulator of immune dysfunction after bone trauma.

OBJECTIVES: To reveal the relationship between the fibulin-2 protein and immune dysfunction after bone trauma. METHODS: Individuals who were admitted to the study were divided into a bone trauma group, a recovered from bone trauma group and a volunteer without bone trauma group based on the reason for admission. Fibulin-2 levels in the three groups were compared. Fibulin-2-knockout (fibulin-2-/- ) mice and wild-type (WT) mice were used to detect susceptibility to infection. Hematoxylin and eosin (HE) staining and immunohistochemical staining were employed to observe pathological changes in each organ from fibulin-2-/- mice and WT mice. RESULTS: In total, 132 patients were enrolled in this study. The fibulin-2 level in the bone trauma group was lower than that in the recovered bone trauma group (3.39 ± 1.41 vs. 4.30 ± 1.38 ng/mL, t = 2.948, p < .05) and also lower than that in the volunteers without bone trauma group (3.39 ± 1.41 vs. 4.73 ± 1.67 ng/mL, t = 4.135, p < .05). Fibulin-2-/- mice are more prone to infection. Compared with those in WT mice, spleen function and thymus function in fibulin-2-/- mice were impaired. Immunohistochemical staining revealed that compared with those in WT mice, significantly fewer CD4+ T cells, CD8+ T cells, and CD19+ B cells were noted in the spleen and thymus of fibulin-2-/- mice. CONCLUSIONS: The plasma fibulin-2 level was lower in patients with bone trauma. Decreased fibulin-2 is associated with immune dysfunction after bone trauma.

Orbital Interactions between the Organic Semiconductor Spacer and the Inorganic Layer in Dion-Jacobson Perovskites Enable Efficient Solar Cells.

2D Dion-Jacobson (DJ) perovskites have become emerging photovoltaic materials owing to their intrinsic structure stability. However, as insulating aliphatic cations are widely used as spacers, the interactions between the spacers and inorganic layers in DJ perovskites have rarely been studied. Here, an organic semiconductor spacer with two covalently connected thiophene rings, namely bithiophene dimethylammonium (BThDMA), is successfully developed for 2D DJ perovskite solar cells (PSCs). An important finding is that there are strong orbital interactions between the conjugated organic spacer and adjacent inorganic layers, whereas no such interactions exist in DJ perovskite using an aliphatic octane-1,8-diaminium (ODA) spacer with similar length. The BThDMA spacer with multiple conjugated aromatic rings can also induce crystal growth with large grain size and preferred vertical orientation, resulting in reduced trap density and improved charge-carrier mobility. As a result, the optimized device based on (BThDMA)MAn -1 Pbn I3 n +1 (nominal n = 5) shows an excellent PCE of 18.1% with negligible hysteresis, which is a record efficiency for 2D DJ PSCs using a spacer with two or more covalently linked aromatic rings. These findings provide a novel and important insight on achieving efficient and stable 2D DJ perovskite solar cells by developing organic semiconductor spacers.

Synthesis optimization of rich-urea carbon-dots and application in the determination of H2S in rich- and barren-liquids of desulphurizing solutions.

In the research of carbon dots (CDs) containing various nitrogen sources, it was first found that urea/citric acid-CDs showed a selective discolouration reaction with sulphide ions. Therefore, by optimizing various synthesis and detection conditions of the CDs determining sulfur ions, such as the raw material ratio, temperature, time, pH, and oxidation atmosphere in the CD synthesis, a discolour CD-probe method for trace-level sulphide ions was developed. The method is environmentally friendly, shows two linear-response ranges in 0.050-1.0 mg L-1 (A = -0.0827c + 0.8366) and 1.0-15 mg L-1 S2- (A = -0.0209c + 0.7587) and can be used for the high and low concentration quantification of sulphide in various wastewaters. Subsequently, in order to realize the separation and detection of sulphide ions in wastewaters or rich- and barren-liquids containing N-methyldiethanolamine and other substances in desulphurizing solutions, an automatic pretreatment system was also established.

Multiple-Noncovalent-Interaction-Stabilized Layered Dion-Jacobson Perovskite for Efficient Solar Cells.

Two-dimensional Dion-Jacobson (DJ) perovskites have shown improved structure stability in comparison with Ruddlesden-Popper (RP) perovskites. However, the mechanism behind the improved stability is still largely unexplored. Here a multifluorinated aromatic spacer, namely, 4F-PhDMA, has been successfully developed for 2D DJ perovskites. It is found that the 2D DJ perovskite with a 4F-PhDMA spacer exhibits a high dissociation energy due to the multiple noncovalent interactions. The optimized 2D DJ device based on the 4F-PhDMA spacer (n = 4) exhibits a champion efficiency of 16.62% with much improved light and thermal stability. This efficiency is much higher than that of the control device using an unfluorinated spacer (n = 4, PCE = 10.11%) and is among the highest efficiencies in aromatic-spacer-based 2D DJ perovskite solar cells (PSCs). Our work highlights the importance of incorporating multiple noncovalent interactions in the 2D DJ perovskite by employing a multifluorinated aromatic spacer to achieve DJ PSCs with both high efficiency and high stability.