Bilayer molecular assembly at a solid/liquid interface as triggered by a mild electric field.

The construction of a spatially defined assembly of molecular building blocks, especially in the vertical direction, presents a great challenge for surface molecular engineering. Herein, we demonstrate that an electric field applied between an STM tip and a substrate triggered the formation of a bilayer structure at the solid-liquid interface. In contrast to the typical high electric-field strength (10(9)  V m(-1) ) used to induce structural transitions in supramolecular assemblies, a mild electric field (10(5)  V m(-1) ) triggered the formation of a bilayer structure of a polar molecule on top of a nanoporous network of trimesic acid on graphite. The bilayer structure was transformed into a monolayer kagome structure by changing the polarity of the electric field. This tailored formation and large-scale phase transformation of a molecular assembly in the perpendicular dimension by a mild electric field opens perspectives for the manipulation of surface molecular nanoarchitectures.

Quantitative and qualitative analysis of contrast-enhanced ultrasound for differentiating benign and malignant superficial enlarged lymph nodes.

Background: In many clinical situations, it is critical to exclude or identify abnormally lymph nodes (LNs). The nature of superficial abnormally LNs is closely related to the stage, treatment, and prognosis of the disease. Ultrasound (US) is an important method for examining superficial LNs due to its cheap and safe characteristics. However, it is still difficult to determine the nature of some LNs with overlapping benign and malignant features in images. Contrast-enhanced ultrasound (CEUS) can be used to evaluate the microperfusion status of tissues in real time, and it can improve diagnostic accuracy to a certain extent. Therefore, in this study, we will analyze the correlation between CEUS quantitative parameters and benign and malignant superficial abnormally LNs, to evaluate the efficacy and value of CEUS in distinguishing benign and malignant superficial LNs. Methods: This study retrospectively analyzed 120 patients of abnormal LNs who underwent US and CEUS at the China-Japan Union Hospital of Jilin University from December 2020 to August 2023. All 120 cases of abnormal LNs underwent US-guided coarse needle biopsy, and accurate pathological results were obtained, along with complete US and CEUS images. According to the pathological results, LNs were divided into benign and malignant groups, and the qualitative and quantitative parameters of US and CEUS between the two groups were analyzed. The cutoff value is determined by the receiver operating characteristic (ROC) curve of the subjects, and sensitivity, specificity, and accuracy are applied to evaluate the ability of the cutoff value to distinguish between the two groups. Results: There were a total of 120 LNs, including 36 in the benign group and 84 in the malignant group. The results showed that malignant LNs were usually characterized by the disappearance of lymphatic hilum, round ness index (L/T) <2, irregular morphology, and the manifestation of uneven perfusion (P<0.05). The differences in the quantitative parameters peak enhancement (PE), rise time (RT), time to peak (TTP), wash-in rate (WIR), and wash-out rate (WOR) were statistically significant (P<0.05). The result showed that RT and TTP in the malignant LNs were higher than those in the benign LNs, while the PE, WIR, and WOR were lower. A comparison of the ∆ values showed that the differences in ∆PE, ∆WIR, and ∆fall time (FT) were statistically significant (P<0.05), Among them, the ∆PE and ∆WIR of malignant LNs were higher than those of benign LNs, while the ∆FT was lower than that of benign LNs. Conclusions: Quantitative analysis of CEUS features is valuable in the diagnosis of benign and malignant LNs, and US combined with CEUS helps to improve the accuracy of identifying the nature of LNs.

Au/TiO2 Hollow Spheres with Synergistic Effect of Plasmonic Enhancement and Light Scattering for Improved Dye-Sensitized Solar Cells.

Au-decorated TiO2 hollow spheres (Au-THS) have been successfully synthesized via a facile one-pot solvothermal method. The Au-THS hybrid features unique hollow structure with a large specific surface area of 120 m2 g-1 and homogeneous decoration of Au nanoparticles, giving rise to enhanced light harvesting and charge generation/separation efficiency. When incorporated into the active layer of dye-sensitized solar cells (DSSCs), an improved power conversion efficiency of 7.3% is obtained, which is increased by 37.7% compared with the controlled P25 DSSC. The underlying mechanism to rationalize the efficiency enhancement can be mainly attributed to the strong synergistic effect of superior light scattering ability of the THS and the plasmonic-enhanced effect rendered by the Au nanoparticles.

Highly Flexible Graphene/Mn3O4 Nanocomposite Membrane as Advanced Anodes for Li-Ion Batteries.

Advanced electrode design is crucial in the rapid development of flexible energy storage devices for emerging flexible electronics. Herein, we report a rational synthesis of graphene/Mn3O4 nanocomposite membranes with excellent mechanical flexibility and Li-ion storage properties. The strong interaction between the large-area graphene nanosheets and long Mn3O4 nanowires not only enables the membrane to endure various mechanical deformations but also produces a strong synergistic effect of enhanced reaction kinetics by providing enlarged electrode/electrolyte contact area and reduced electron/ion transport resistance. The mechanically robust membrane is explored as a freestanding anode for Li-ion batteries, which delivers a high specific capacity of ∼800 mAh g(-1) based on the total electrode mass, along with superior high-rate capability and excellent cycling stability. A flexible full Li-ion battery is fabricated with excellent electrochemical properties and high flexibility, demonstrating its great potential for high-performance flexible energy storage devices.

In situ observation of electrolyte-concentration-dependent solid electrolyte interphase on graphite in dimethyl sulfoxide.

High lithium salt concentration strategy has been recently reported to be an effective method to enable various organic solvents as electrolyte of Li-ion batteries. Here, we utilize in situ atomic force microscopy (AFM) to investigate the interfacial morphology on the graphite electrode in dimethyl sulfoxide (DMSO)-based electrolyte of various concentrations. The significant differences in interfacial features of the graphite in electrolytes of different concentrations are revealed. In the concentrated electrolyte, stable films form primarily at the step edges and defects on the graphite surface after initial electrochemical cycling. On the other hand, in the dilute electrolyte, DMSO-solvated lithium ions constantly intercalate into graphite layers, and serious decomposition of solvent accompanied by structural deterioration of the graphite surface is observed. The in situ AFM results provide direct evidence for the concentration-dependent interface reactions between graphite electrode and DMSO-based electrolyte.

Catalytic Performance of Pt/Reduced Graphene Oxide Composites to Methanol Electrochemical Oxidation: Optimization of Mass-Specific Activity.

Series of catalysts made of Pt nanoparticles supported on reduced graphene oxides (Pt/RGO) were synthesized and tested in methanol oxidation reaction, aiming for optimizing the mass-specific activity of prepared Pt/RGO composites. The loading amount of Pt is controlled through setting different reaction time and determined precisely by atomic absorption spectrophotometer. The structure of Pt/RGO composites is characterized by X-ray diffraction, transmission electron microscopy and Raman spectroscopy. The electrochemical testing data reveal that the Pt/RGO-mass-specific activity, judged by current density and long-term stability, is maximized in the sample in which cooperation of the Pt loading amount and electrochemical active surface area (ECSA) per amount of Pt is best optimized. The performance of the catalyst with smallest Pt particles or highest Pt loading amount is dragged down by either too less Pt loading or poor ECSA per amount of Pt. The results in this research demonstrate that the mass-normalized activity of whole catalyst, which is associated with the anticipated power output per amount of catalyst, could be enhanced significantly by deliberate tuning of fabrication process.

Depression-like Behavior Induced by Nesfatin-1 in Rats: Involvement of Increased Immune Activation and Imbalance of Synaptic Vesicle Proteins.

Depression is a multicausal disorder and has been associated with metabolism regulation and immuno-inflammatory reaction. The anorectic molecule nesfatin-1 has recently been characterized as a potential mood regulator, but its precise effect on depression and the possible mechanisms remain unknown, especially when given peripherally. In the present study, nesfatin-1 was intraperitoneally injected to the rats and the depression-like behavior and activity of the hypothalamic-pituitary-adrenal (HPA) axis were evaluated. The plasma concentrations of nesfatin-1, interleukin 6 (IL-6), and C-reactive protein (CRP); and the hypothalamic expression levels of nesfatin-1, synapsin I, and synaptotagmin I mRNA were evaluated in nesfatin-1 chronically treated rats. The results showed that both acute and chronic administration of nesfatin-1 increased immobility in the forced swimming test (FST), and resulted in the hyperactivity of HPA axis, as indicated by the increase of plasma corticosterone concentration and hypothalamic expression of corticotropin-releasing hormone (CRH) mRNA. Moreover, after chronic nesfatin-1 administration, the rats exhibited decreased activity and exploratory behavior in the open field test (OFT) and increased mRNA expression of synapsin I and synaptotagmin I in the hypothalamus. Furthermore, chronic administration of nesfatin-1 elevated plasma concentrations of IL-6 and CRP, which were positively correlated with despair behavior, plasma corticosterone level, and the hypothalamic mRNA expression of synapsin I and synaptotagmin I. These results indicated that exogenous nesfatin-1 could induce the immune-inflammatory activation, which might be a central hug linking the depression-like behavior and the imbalanced mRNA expression of synaptic vesicle proteins in the hypothalamus.

Acute, but not chronic, stress increased the plasma concentration and hypothalamic mRNA expression of NUCB2/nesfatin-1 in rats.

Nesfatin-1, a newly discovered satiety peptide, has recently been reported to be involved in the stress response. Stress-induced expression of nesfatin-1 has been reported and few studies focus on its expression in the hypothalamus, which is the center of the stress response. To test our hypothesis that peripheral and hypothalamic nesfatin-1 overexpression should play an important role in the stress response and the associated hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis, acute stress (AS) was induced using water avoidance stress (WAS), and chronic unpredictable mild stress (CUMS) was also induced using 3 consecutive weeks of 7 different stressors. The behavior of CUMS rats was evaluated by an open field test (OFT), sucrose preference test (SPT), and forced swimming test (FST). The activity of the HPA axis was detected by measurement of the plasma corticosterone concentration and hypothalamic mRNA expression of corticotropin-releasing-hormone (CRH). The plasma concentration and hypothalamic mRNA expression of nesfatin-1 were measured with an enzyme-linked immunosorbent assay (ELISA) and real-time fluorescent quantitative PCR, respectively. The results showed that both AS and CUMS increased the plasma corticosterone concentration and hypothalamic CRH mRNA expression. Depression-like behavior was induced in CUMS rats, as indicated by a decreased movement distance, frequency of rearing and grooming in the OFT, and sucrose preference index and increased immobility in the FST. Moreover, the AS rats showed increased plasma concentration and hypothalamic mRNA expression of nesfatin-1, which were positively correlated with the plasma corticosterone concentration and hypothalamic CRH expression, respectively. These results indicated that acute stress, but not chronic stress, increased the plasma concentration and hypothalamic mRNA expression of NUCB2/nesfatin-1 in rats.

Facet dependent SEI formation on the LiNi(0.5)Mn(1.5)O4 cathode identified by in situ single particle atomic force microscopy.

A facile protocol is developed for the direct observation and characterization of a single particle electrode during the lithium ion battery operation by using in situ AFM. The SEI formation on the LiNi0.5Mn1.5O4 particle cathode surface is found to be highly related to the exposed planes.

Single nanowire electrode electrochemistry of silicon anode by in situ atomic force microscopy: solid electrolyte interphase growth and mechanical properties.

Silicon nanowires (SiNWs) have attracted great attention as promising anode materials for lithium ion batteries (LIBs) on account of their high capacity and improved cyclability compared with bulk silicon. The interface behavior, especially the solid electrolyte interphase (SEI), plays a significant role in the performance and stability of the electrodes. We report herein an in situ single nanowire atomic force microscopy (AFM) method to investigate the interface electrochemistry of silicon nanowire (SiNW) electrode. The morphology and Young's modulus of the individual SiNW anode surface during the SEI growth were quantitatively tracked. Three distinct stages of the SEI formation on the SiNW anode were observed. On the basis of the potential-dependent morphology and Young's modulus evolution of SEI, a mixture-packing structural model was proposed for the SEI film on SiNW anode.