Superlong Metal-Organic Framework Micro-/Nanofibers for Selective Vitamin Absorption.

Superlong MOF-74-type micro/nanofibers, which have aspect ratios much higher than 200, are synthesized via nanoparticulate MOF-mediated recrystallization. Co-MOF-74 microfibers have high crystallinity, whereas Co-MOF-74-II nanofibers are composed of nanocrystals and amorphous phases, even though they have nanofibrous morphology. Both MOFs consist of plenty of micropores with diameters in the range of 1.0 to 2.0 nm, and they exhibit high thermal stability with a decomposition temperature higher than 260.0 °C. The MOFs are demonstrated for selective absorption of some vitamins including riboflavin, folic acid, and 5-methyltetrahydrofolate. Co-MOF-74-II nanofibers can efficiently absorb riboflavin and folic acid from their aqueous solution with absorption percentages approaching 90.0%, and they have enhanced capability for absorbing tocopherol in methanol. The micro/nanofibrous morphology, together with the capability for selective vitamin absorption, makes the novel MOFs highly promising for applications in micro-solid-phase extraction.

In Situ Monitoring of the Surface Evolution of a Silver Electrode from Polycrystalline to Well-Defined Structures.

Capturing the surface-structural dynamics of metal electrocatalysts under certain electrochemical environments is intriguingly desired for understanding the behavior of various metal-based electrocatalysts. However, in situ monitoring of the evolution of a polycrystalline metal surface at the interface of electrode-electrolyte solutions at negative/positive potentials with high-resolution scanning tunneling microscopy (STM) is seldom. Here, we use electrochemical STM (EC-STM) for in situ monitoring of the surface evolution process of a silver electrode in both an aqueous sodium hydroxide solution and an ionic liquid of 1-methyl-1-octylpyrrolidinium bis(trifluoromethylsulfonyl) amide driven by negative potentials. We found silver underwent a surface change from a polycrystalline structure to a well-defined surface arrangement in both electrolytes. In NaOH aqueous solution, the silver surface transferred in several minutes at a turning-point potential where hydrogen adsorbed and formed mainly (111) and (100) pits. Controversially, the surface evolution in the ionic liquid was much slower than that in the aqueous solution, and cation adsorption was observed in a wide potential range. The surface evolution of silver is proposed to be linked to the surface adsorbates as well as the formation of their complexes with undercoordinated silver atoms. The results also show that cathodic annealing of polycrystalline silver is a cheap, easy, and reliable way to obtain quasi-ordered crystal surfaces.

Characteristics and Antioxidant Activity of Lignans in Schisandra chinensis and Schisandra sphenanthera from Different Locations.

Twenty Schisandra samples were collected from different locations. Contents of 7 lignans in the samples were determined and analyzed by HPLC method coupled with hierarchical clustering analysis (HCA) and principal component analysis (PCA), and the antioxidant capacity of Schisandra from the different locations was evaluated by reducing power, ferric thiocyanate (FTC) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) assay. The results showed that there was a significant difference in the content of lignans between Schisandra chinensis and Schisandra sphenanthera. The Schisandra sphenanthera samples in the southwest of China were significantly different from those from the other locations. The antioxidant capacity of Schisandra chinensis was significantly superior to that of Schisandra sphenanthera, and the main antioxidant components were schisandrol A, schisandrol B and schisandrin B based on the result of discrimination analyses. The differences in the chemical composition and antioxidant activity of lignans in Schisandra chinensis and Schisandra sphenanthera from the different locations were investigated in this study, which may provide an experimental basis for the quality control of Schisandra.

A Janus heteroatom-doped carbon electrocatalyst for hydrazine oxidation.

The trade-off between the intrinsic activity and electronic conductivity of carbon materials is a major barrier for electrocatalysis. We report a Janus-type carbon material combining electrically conductive nitrogen-doped carbon (NC) and catalytically active boron, nitrogen co-doped carbon (BNC). The integration of NC with BNC can not only ensure high electronic conductivity of the hybrid, but also achieve an enhancement in the intrinsic activity of the BNC side due to the electron redistribution on their coupling interfaces. In the electrocatalytic hydrazine oxidation reaction (HzOR), the Janus carbon electrocatalyst exhibits superior activity than their single counterparts and simple physical mixtures. Density functional theory calculations reveal that the NC/BNC interfaces simultaneously promote efficient electron transport and decrease the free energy of the rate-determining step in the HzOR process.

Intense and Superflat White Laser with 700-nm 3-dB Bandwidth and 1-mJ Pulse Energy Enabling Single-Shot Subpicosecond Pulse Laser Spectroscopy.

An optical spectrometer is a basic spectral instrument that probes microscopic physical and chemical properties of macroscopic objects but generally suffers from difficulty in broadband time-resolved measurement. In this work, we report the creation of ultrabroadband white-light laser with a 3-dB bandwidth covering 385 to 1,080 nm, pulse energy of 1.07 mJ, and pulse duration of several hundred femtoseconds by passing 3-mJ pulse energy, 50-fs pulse duration Ti:Sapphire pulse laser through a cascaded fused silica plate and chirped periodically poled lithium niobate crystal. We utilize this unprecedented superflat, ultrabroadband, and intense femtosecond laser light source to build a single-shot (i.e., single-pulse) subpicosecond pulse laser ultraviolet-visible-near-infrared spectrometer and successfully measure various atomic and molecular absorption spectra. The single-shot ultrafast spectrometer may open up a frontier to monitor simultaneously the ultrafast dynamics of multiple physical and chemical processes in various microscopic systems.

Dimensional Design for Surface-Enhanced Raman Spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) is a vibrational spectroscopy technique that enables specific identification of target analytes with sensitivity down to the single-molecule level by harnessing metal nanoparticles and nanostructures. Excitation of localized surface plasmon resonance of a nanostructured surface and the associated huge local electric field enhancement lie at the heart of SERS, and things will become better if strong chemical enhancement is also available simultaneously. Thus, the precise control of surface characteristics of enhancing substrates plays a key role in broadening the scope of SERS for scientific purposes and developing SERS into a routine analytical tool. In this review, the development of SERS substrates is outlined with some milestones in the nearly half-century history of SERS. In particular, these substrates are classified into zero-dimensional, one-dimensional, two-dimensional, and three-dimensional substrates according to their geometric dimension. We show that, in each category of SERS substrates, design upon the geometric and composite configuration can be made to achieve an optimized enhancement factor for the Raman signal. We also show that the temporal dimension can be incorporated into SERS by applying femtosecond pulse laser technology, so that the SERS technique can be used not only to identify the chemical structure of molecules but also to uncover the ultrafast dynamics of molecular structural changes. By adopting SERS substrates with the power of four-dimensional spatiotemporal control and design, the ultimate goal of probing the single-molecule chemical structural changes in the femtosecond time scale, watching the chemical reactions in four dimensions, and visualizing the elementary reaction steps in chemistry might be realized in the near future.

Size-dependent electrocatalytic activity of gold nanoparticles on HOPG and highly boron-doped diamond surfaces.

Gold nanoparticles were prepared by electrochemical deposition on highly oriented pyrolytic graphite (HOPG) and boron-doped, epitaxial 100-oriented diamond layers. Using a potentiostatic double pulse technique, the average particle size was varied in the range from 5 nm to 30 nm in the case of HOPG as a support and between < 1 nm and 15 nm on diamond surfaces, while keeping the particle density constant. The distribution of particle sizes was very narrow, with standard deviations of around 20% on HOPG and around 30% on diamond. The electrocatalytic activity towards hydrogen evolution and oxygen reduction of these carbon supported gold nanoparticles in dependence of the particle sizes was investigated using cyclic voltammetry. For oxygen reduction the current density normalized to the gold surface (specific current density) increased for decreasing particle size. In contrast, the specific current density of hydrogen evolution showed no dependence on particle size. For both reactions, no effect of the different carbon supports on electrocatalytic activity was observed.

The prognostic value of C-reactive protein/albumin ratio in human malignancies: an updated meta-analysis.

PURPOSE: This study aims to investigate the prognostic value of pretreatment C-reactive protein/albumin ratio (CAR) in human malignancies by an updated meta-analysis. METHODS: PubMed, Web of Science, Cochrane Library and Wanfang databases were searched. Pooled hazard ratios (HRs) and odds ratios (ORs) with their corresponding 95% confidence intervals (CIs) were used as effective values. RESULTS: A total of 25 studies with 12,097 patients were included in this meta-analysis. Pooled results showed that high pretreatment CAR was associated with poor overall survival (OS) (HR =1.99, 95% CI: 1.65-2.40, P=0.000) and poor disease-free survival (HR =1.55, 95% CI: 1.34-1.79, P=0.000). In addition, high pretreatment CAR was associated with increased 5-year mortality (OR =2.74, 95% CI: 2.11-3.55, P=0.000). Moreover, subgroup analysis demonstrated that high CAR was associated with poor OS despite variations in publication year, country, sample size, CAR cut-off value and treatment. However, high CAR was associated with poor OS in human malignancies except colorectal cancer (HR =1.64, 95% CI: 0.96-2.80, P=0.069). CONCLUSION: High pretreatment CAR indicates poor prognosis in human malignancies except colorectal cancer. Thus, pretreatment CAR serves as a prognostic marker in human malignancies and could be used in the evaluation of prognosis in clinical work.

Decorin inhibits the proliferation of HepG2 cells by elevating the expression of transforming growth factor-ß receptor II.

The aim of the present study was to investigate the effects of decorin (DCN) on the proliferation of human hepatoma HepG2 cells and the involvement of transforming growth factor-ß (TGF-ß) signaling pathway. A vector containing DCN was transfected into HepG2 cells with the use of Lipofectamine 2000. Cell proliferation was assessed with an MTT assay, and western blot analysis was used to detect the protein expression of TGF-ß receptor I (TGF-ßRI), phosphorylated TGF-ßRI, p15 and TGF-ßRII. In addition, small interfering RNA (siRNA) silencing was performed to knock down the target gene. The results indicated that, compared with the control group, cell proliferation was significantly decreased in HepG2 cells transfected with DCN. In addition, DCN transfection significantly increased the phosphorylation level of TGF-ßRI in HepG2 cells. The expression of the downstream factor p15 was also significantly elevated in the DCN-transfected HepG2 cells. Furthermore, DCN transfection significantly elevated the expression level of TGF-ßRII in HepG2 cells. By contrast, the silencing of TGF-ßRII significantly decreased the phosphorylation of TGF-ßRI in DCN-transfected HepG2 cells. In addition, TGF-ßRII silencing abolished the effects of DCN on the proliferation of HepG2 cells. In conclusion, DCN elevated the expression level of TGF-ßRII, increased the phosphorylation level of TGF-ßRI, enhanced the expression of p15, and finally inhibited the proliferation of HepG2 cells. These findings may contribute to the understanding of the role of DCN in the pathogenesis of hepatic carcinoma and assist in the disease treatment.

Decorin protects human hepatoma HepG2 cells against oxygen-glucose deprivation via modulating autophagy.

This study is to investigate the effects of decorin (DCN) on human hepatoma HepG2 cells under oxygen-glucose deprivation (OGD) condition. HepG2 cells were cultured under OGD condition. CCK-8 assay was used to assess the cell survival, and flow cytometry was performed to detect the apoptosis. Protein expression levels were detected with Western blot analysis. Transfection was performed with liposome, and cells were screened with G418. The cell survival rates were significantly decreased in the OGD groups. When treated with autophagy inhibitor 3-MA, the survival rates were further declined in these cells. Moreover, flow cytometry indicated that apoptosis occurred in the HepG2 cells under OGD condition, and the apoptosis rates were significantly increased by the 3-MA treatment. Western blot analysis showed that, the expression levels of DCN were significantly elevated in OGD-preconditioned HepG2 cells. Meanwhile, the expression level of Beclin1 and the LC3BI/LC3BII ratio were significantly increased, while the expression level of P62 was significantly decreased, in HepG2 cells under OGD condition. Over-expression of DCN significantly increased the expression level of Beclin1 and the LC3BI/LC3BII ratio, while no significant changes were observed in the P62 expression level, in HepG2 cells. Under the OGD condition, the apoptosis rate was also significantly decreased in DCN-transfected HepG2 cells. DCN protects HepG2 cells against OGD-induced injury, via regulating autophagy. These results might contribute to a better understanding of the roles of DCN and autophagy in hepatocellular carcinoma, and the potential treatment for the disease.