Jamming of Miscible Liquids via Electrostatic Repulsion Between Polystyrene-Modified Gold Nanorods and Toluene.

Structured liquids in miscible fluids, due to ineffective resistance to withstand particle self-diffusion, differ from that in immiscible liquids because of interfacial interactions. Here, a kind of structured liquid, jammed by thiol-terminated polystyrene-modified gold nanorods (GNRs) within tetrahydrofuran and toluene (TOL), is developed by introducing electrostatic repulsion to counterbalance the self-diffusion of GNRs. First-principle calculations reveal charge transfer between the GNRs and TOL, resulting in the electrostatic repulsion. The structured liquids can be regarded as mimic "loading vehicles" to controllably carry and transport matter under electric or magnetic fields, where release rate can be adjusted by changing the concentration of the soluble matter for slow release and using the photothermal effect of the assembled GNRs for fast release. This work has developed a new assembly mechanism to form structured liquids, allowing the construction of a flexible and robust droplet platform with possible applications in microreactors, biomimetic permeable membranes, and functional liquid robots.

Topological Flat Bands in 2D Breathing-Kagome Lattice Nb3 TeCl7.

Flat bands (FBs) can appear in two-dimensional (2D) geometrically frustrated systems caused by quantum destructive interference (QDI). However, the scarcity of pure 2D frustrated crystal structures in natural materials makes FBs hard to be identified, let alone modulate FBs relating to electronic properties. Here, the experimental evidence of the complete electronic QDI induced FB contributed by the 2D breathing-kagome layers of Nb atoms in Nb3 TeCl7 (NTC) is reported. An identical chemical state and 2D localization characteristics of the Nb breathing-kagome layers are experimentally confirmed, based on which NTC is demonstrated to be a superior concrete candidate for the breathing-kagome tight-binding model. Furthermore, it theoretically establishes the tunable roles of the on-site energy over Nb sites on bandwidth, energy position, and topology of FBs in NTC. This work opens an aveanue to manipulate FB characteristics in these 4d transition-metal-based breathing-kagome materials.

Effect of rhodamine 6G dye molecular interactions on counterintuitive self-assembly of noble metal nanorods.

HYPOTHESIS: Self-assembled nanostructures with highly ordered and diversified patterns can be obtained by adding additives that directionally control the interparticle interactions. However, due to the complex non-covalent weak interactions in the self-assembly process, the active mechanism of additives is not fully understood, resulting in the limitation of obtaining the nano-superstructures. The introduction of rhodamine 6G (R6G) enables gold nanorods (GNRs) self-assembled into a counterintuitive tetragonal superlattice, during which the exploration of the influence of R6G molecular interactions on the GNRs self-assembly is of importance. EXPERIMENTS: We present the detailed investigations of spacial configuration, binding modes, and aggregated degree of R6G molecule on formation of the tetragonal GNRs superlattices by combining the experimental and simulated results. FINDINGS: By analyzing the peak position and peak intensity in the fluorescent spectra of assembled samples and pure R6G samples, H-dimer is verified as the main cause for inducing the tetragonal superstructures. Molecular dynamics simulations reveal that 2-3 H-dimers adsorbed obliquely in a zigzag chain manner on the surface of GNRs is the most stable state of the self-assembly. This work would contribute to a deeper understanding of the complex colloidal nanoparticle self-assemblies and push forward the development of the bottom-up nanoscale superstructures.

[Determination of steviol in Stevia Rebaudiana leaves by near infrared spectroscopy].

The objective of the present study is to develop a method for rapid determination of the content of stevioside (ST) and rebaudioside A (RA) in Stevia Rebaudiana leaves. One hundred and five samples of stevia from different areas containing ST of 0.27%-1.40% and RA of 0.61%-3.98% were used. The 105 groups' NIRS diagram was processed by different methods including subtracting a straight line (SLS), multiplicative scatter correction (MSC), first derivative (FD), second derivative (SD) and so on, and then all data were analyzed by partial least square (PLS). The study showed that SLS can be used to extracted spectra information thoroughly to analyze the contents of ST, the correlation coefficients of calibration (Re), the root-mean-square errors of calibration (RMSEC) and prediction (RMSEP), and the residual predictive deviation (RPD) were 0.986, 0.341, 1.00 and 2.8, respectively. The correlation coefficients of RA was 0.967, RMSEC was 1.50, RMSEP was 1.98 and RPD was 4.17. The results indicated that near infrared spectroscopy (NIRS) technique offers effective quantitative capability for ST and RA in Stevia Rebaudiana leaves. Then the model of stevia dried leaves was used to compare with the stevia powder near infrared model whose correlation coefficients of ST was 0.986, RMSEC was 0.32, RMSEP was 0.601 and RPD was 2.86 and the correlation coefficients of RA was 0.968, RMSEC was 1.50, RMSEP was 1.48 and RPD was 4.2. The result showed that there was no significant difference between the model of dried leaves and that of the powders. However, the dried leaves NIR model reduces the unnecessary the steps of drying and grinding in the actual detection process, saving the time and reducing the workload.