Total synthesis of calystegine A7

A straightforward chiral pool synthesis for the glycosidase inhibitor calystegine A₇ (isolated from Lycium chinense) from methyl α-d-glucopyranoside is described. Keysteps of this synthesis include a ultrasound assisted Zn-mediated tandem ring opening reaction followed by a Grubbs' catalyst mediated ring closure metathesis.     

Electricity generation by an enriched phototrophic consortium in a microbial fuel cell

Microbial fuel cell (MFC) technology is a novel electricity generation process catalyzed by microorganisms. Much progress is made in the design and construction of MFCs, however the diversity of the electrochemically active microorganisms and the electricity generation mechanisms remain a black box. As sun is a predominantly unused energy resource, here we present a highly enriched phototrophic consortium that can produce electricity in an “H” typed MFC at a high power density (2650 mW m⁻², normalized to membrane area) in light, which was eightfold of that produced by non-enriched consortium in the same reactor. Light–dark shift experiments showed that light contributed to the electricity generation. A microbial excreted mediator assisted the electron transfer to the electrode. During the experiment, the accumulation of the mediator over time enhanced the electron transfer rate. The excitation–emission matrix fluorescence spectroscopy results indicated indole group containing compound representing the dominant mediator component.     

不同直径碳纳米管的抗电化学氧化性

本文比较了由化学气相沉积法制备的不同直径(在100 nm以内)的多壁碳纳米管(CNT)的抗电化学氧化性.将CNT电极于1.2 V(vs.RHE)下电氧化120 h,记录氧化电流~时间变化曲线;X射线光电子能谱(XPS)分析氧化前后CNT的表面化学组成.结果表明,随着CNT直径的减小,其氧化电流降低,但其中以为10~20 nm的CNT电极氧化电流最小,表面氧的增量也最小,即被氧化的程度最低,抗电化学氧化性最强.根据不同直径CNT的缺陷位、不定型碳的丰度和碳原子的应力能,分析了其抗电化学氧化性差异的原因.     

Cs–Ba separation using N2O as a reactant gas in a Multiple Collector-Inductively Coupled Plasma Mass Spectrometer collision-reaction cell: Application to the measurements of Cs isotopes in spent nuclear fuel samples

In the general frameworks of the nuclear fuel cycle and environmental research field, the Cs isotopic composition must be known with high precision and accuracy. The direct determination of Cs isotopes by mass spectrometry techniques is generally hampered by the presence of Ba isobaric interferences however. Here we present a new method which takes advantage of the collision-reaction cell based Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) and allows to analyse Cs isotopes in the presence of Ba without prior separation step. The addition of N₂O gas in the cell leads to an antagonistic behavior of Cs⁺ and Ba⁺ as the latter reacts with the gas to form BaO⁺ and BaOH⁺ products whereas Cs⁺ remains unreactive. The efficiency of the method was demonstrated for an UOx sample by comparing the results obtained (1) from the measurements of pure Cs fractions and (2) from Fission Products fractions containing more than 30 ionisable elements in addition to Cs, Ba, and where U and Pu were previously removed by using ion exchange resin. An excellent agreement is achieved between each set of experiments with an external reproducibility always better than 0.5% (RSD, k = 2). This study confirms the strong potential of collision–reaction cell to measure Cs isotopes in presence of interfering Ba, precluding therefore former systematic chemical separations.     

Liquid interfacial nanoarchitectonics: Molecular machines,organic semiconductors,nanocarbons, stem cells,and others

The concept of nanoarchitectonics has been proposed as an extensional development of nanotechnology through fusions with material science and the other fields. In nanoarchitectonics, nano-units of atoms, molecules, and nanomaterials are architected into construction of functional material systems. In order to assemble intended structures or hierarchical structures from nano-units, it is more useful to confine nano-units at the interface. In addition, nanoarchitectonics is expected to output functions by harmonizing many units in dynamic environments. However, the liquid interfaces still have lots of unexplored matters in nanoscale because supports by advanced apparatus and techniques in nanotechnology are not always available. Specifically, this review paper summarizes examples of research on molecular manipulation, molecular arrangement and assembly, materials synthesis, and life manipulation at the liquid interface. These examples demonstrate that the liquid interface enables the control of dynamic functions of various size regions, from molecular-level phenomena such as the control of molecular machines to techniques of living creature size such as the control of stem cell differentiation. Liquid interfaces are very useful environments for controlling dynamic functions for a wide range of targets and would have tremendous potential in terms of functional exploration. The great potential of nanoarchitectonics at the liquid interface and the challenges to be solved in the future are also discussed.     

High Hydrostatic Pressure to Increase the Biosynthesis and Extraction of Phenolic Compounds in Food: A Review

Phenolic compounds from fruits and vegetables have shown antioxidant, anticancer, anti-inflammatory, among other beneficial properties for human health. All these benefits have motivated multiple studies about preserving, extracting, and even increasing the concentration of these compounds in foods. A diverse group of vegetable products treated with High Hydrostatic Pressure (HHP) at different pressure and time have shown higher phenolic content than their untreated counterparts. The increments have been associated with an improvement in their extraction from cellular tissues and even with the activation of the biosynthetic pathway for their production. The application of HHP from 500 to 600 MPa, has been shown to cause cell wall disruption facilitating the release of phenolic compounds from cell compartments. HPP treatments ranging from 15 to 100 MPa during 10–20 min at room temperature have produced changes in phenolic biosynthesis with increments up to 155%. This review analyzes the use of HHP as a method to increase the phenolic content in vegetable systems. Phenolic content changes are associated with either an immediate stress response, with a consequent improvement in their extraction from cellular tissues, or a late stress response that activates the biosynthetic pathways of phenolics in plants.     

Plant-Derived Molecule 4-Methylumbelliferone Suppresses FcεRI-Mediated Mast Cell Activation and Allergic Inflammation

Mast cells (MCs) are an important treatment target for high-affinity IgE Fc receptor (FcεRI)-mediated allergic diseases. The plant-derived molecule 4-methylumbelliferone (4-MU) has beneficial effects in animal models of inflammation and autoimmunity diseases. The aim of this study was to examine 4-MU effects on MC activation and probe the underlying molecular mechanism(s). We sensitized rat basophilic leukemia cells (RBLs) and mouse bone marrow-derived mast cells (BMMCs) with anti-dinitrophenol (DNP) immunoglobulin (Ig)E antibodies, stimulated them with exposure to DNP-human serum albumin (HSA), and then treated stimulated cells with 4-MU. Signaling-protein expression was determined by immunoblotting. In vivo allergic responses were examined in IgE-mediated passive cutaneous anaphylaxis (PCA) and ovalbumin (OVA)-induced active systemic anaphylaxis (ASA) mouse models. 4-MU inhibited β-hexosaminidase activity and histamine release dose-dependently in FcεRI-activated RBLs and BMMCs. Additionally, 4-MU reduced cytomorphological elongation and F-actin reorganization while down-regulating IgE/Ag-induced phosphorylation of SYK, NF-κB p65, ERK1/2, p38, and JNK. Moreover, 4-MU attenuated the PCA allergic reaction (i.e., less ear thickening and dye extravasation). Similarly, we found that 4-MU decreased body temperature, serum histamine, and IL4 secretion in OVA-challenged ASA model mice. In conclusion, 4-MU had a suppressing effect on MC activation both in vitro and in vivo and thus may represent a new strategy for treating IgE-mediated allergic conditions.     

两亲性D-π-A型有机染料在染料敏化太阳能电池中的应用

设计合成了6个带有烷基链的D-π-A型有机光敏染料应用于染料敏化太阳能电池. 发现长链烷基有利于电池开路光电压的提高. 利用脂肪酸共敏化可进一步提高染料分子的敏化效果, 且提高的程度与脂肪酸的链长有重要关系.