Exogenous silicon applied at appropriate concentrations is effective at improving tomato nutritional and flavor qualities.

Silicon can mitigate biotic and abiotic stresses in various plants; however, its effects on tomato quality under normal growth conditions are remain unclear. We used a randomized design with four Si treatments, CON (0 mmol/L), T1 (0.6 mmol/L), T2 (1.2 mmol/L), and T3 (1.8 mmol/L) on tomato fruit components Chlorogenic acid and rutin, among polyphenolic components, were increased by 56.99% and 20.31%, respectively, with T2 treatment compared to CON concentrations. T2 increased the sugar-acid ratio by 19.21%, compared to that with the CON treatment, and increased fruit Ca and Mg contents, compared to those with other treatments, improving the characteristic aroma. Furthermore, silicon application reduced the abscisic acid content by 112%, promoting ripening. Endogenous gibberellin, auxin, and salicylic acid, which retard fruit ripening and softening, were increased by 34.96%, 14.56%, and 35.21%, respectively. These findings have far-reaching implications for exogenous Si applications to enrich tomato nutritional and flavor qualities.

Study on Microstructure Characteristics of Axially Braided Carbon/Carbon Composites Based on SEM and Micro-CT.

In order to study the microstructure characteristics of an axially braided Carbon/Carbon (C/C) composite, a comprehensive observation and study of the mesoscopic and microstructure characteristics of an axially braided C/C composite is conducted. Scanning electron microscopy and Micro-CT were used to obtain the microstructure characteristics and distribution rules of the axially braided C/C composite material. The physical model of the material and the geometric model of the representative unit were established. At the same time, the characteristics of this kind of material are also obtained. The microstructure characteristics show that the axially braided C/C composite is a polymer with cracks and pores of different sizes, which is a three-dimensional and four-directions carbon fiber braided body as the reinforcing phase and pitch carbon as the reinforcing matrix. The microcosmic data obtained in this chapter is the basis for carrying out material property prediction and qualitative comparison of macro performance.

N-Doped graphene-supported PdCu nanoalloy as efficient catalyst for reducing Cr(vi) by formic acid.

Reducing Cr(vi) to Cr(iii) with formic acid is desirable for environmental protection, but the sluggish kinetics limits its practical application, which currently motivates the intensive study of efficient catalysts for this redox reaction. Here bimetallic PdCu nanoalloy (∼5 nm in size) supported by N-doped graphene was synthesized through a one-pot hydrothermal process. The catalytic activity of PdCu nanoalloy highly depends on the Pd/Cu atomic ratio and N-doped graphene support. The obtained Pd6Cu4/NG shows superior catalysis towards the Cr(vi) reduction by formic acid with a high kinetic constant (kn = 23.2 min-1 mg-1) and a low activation energy (Ea = 34.9 kJ mol-1). Active H atoms were found to be the exact reductant for the Cr(vi) reduction, quite different from the reported H2-reduction route. The enhanced catalysis originates from the electronic and geometric modification of active Pd after formation of PdCu alloy. Electron transfer from Cu to Pd enhances the electron density of Pd atoms, which favors the adsorption of the bridging formate intermediate and subsequent generation of active H atoms over PdCu/NG. The catalyst can be recycled five times without obvious loss of activity. Our work provides an example to explore the alloying effect on the catalytic behavior of PdCu alloy, which may shed light on developing other advanced nanoalloys for Cr(vi) reduction.

Catalytic reduction of 4-nitrophenol over Ni-Pd nanodimers supported on nitrogen-doped reduced graphene oxide.

Catalytic reduction of toxic 4-nitrophenol to 4-aminophenol over magnetically recoverable nanocatalysts has attracted much attention. Herein, we report a Ni-Pd/NrGO catalyst through the growth of Ni-Pd nanodimers (NDs) on nitrogen-doped reduced graphene oxide (NrGO). The Ni-Pd NDs show a heterogeneous nanostructure with Ni and Pd subparts contacting with each other, remarkably different from the frequently-observed core/shell nanoparticles (NPs) or nanoalloy. The formation of Ni-Pd NDs follows an initial deposition of Pd NPs on the graphene and in-situ catalytic generation of Ni subparts over the newly-generated Pd NPs. The resulting Ni-Pd/NrGO exhibits a superior catalytic activity towards the reduction of 4-nitrophenol at room temperature with a high rate constant (3400s-1g-1) and a low activated energy (29.1kJmol-1) as compared to unsupported Ni-Pd NDs and supported monometallic catalysts. The conversion rate of 4-NP is calculated to be 99.5% and the percent yield (%) of 4-AP is as high as 99.1%. A synergistic catalysis mechanism is rationally proposed, which is ascribed to the electronic modification of Ni-Pd metals due to the strong metal/support interaction (SMSI) effect as well as the electron transfer between Ni and Pd. The hybrid catalyst shows soft ferromagnetic properties and can be magnetically separated and recycled without obvious loss of activity.