相转移催化合成黄豆黄苷的研究

以4-甲氧基间苯二酚和对羟基苯乙腈通过Hoesch反应制备的7,4'-二羟基-6-甲氧基异黄酮(黄豆黄素)为苷元,以三(3,6-二氧杂庚基)胺(TDA-1)为相转移催化剂,碳酸氢钠/氯化钾体系为碱性介质,研究了黄豆黄素与1-溴-2,3,4,6-O-四乙酰基-α-D-吡喃葡萄糖进行偶联反应制备大豆异黄酮黄豆黄苷的合成工艺,糖苷化反应收率为77%,结构经IR和1H NMR以及元素分析加以确证.     

Ni-Catalyzed Regioselective Hydroarylation of 1-Aryl-1,3-Butadienes with Aryl Halides

An efficient nickel-catalyzed regioselective hydroarylation of 1,3-dienes with aryl halides and a silane has been developed, affording a range of allylic arenes in good to excellent yields under mild conditions. This method exhibits broad substrate scope, and excellent functional group tolerance. Late-stage modification of complex architectures was demonstrated.     

Asymmetric phase-transfer catalysts bearing multiple hydrogen-bonding donors: Synthesis and application in nitro-Mannich reaction of isatin-derived N-Boc ketimines

A series of bifunctional asymmetric phase-transfer catalysts bearing multiple hydrogen-bonding donors derived from cinchona alkaloids are synthesized, and successfully applied to asymmetric nitro-Mannich of isatin-derived N-Boc ketimines. The products 3-substituted 3-amino-oxindoles were constructed in excellent yields (96–99%) and good enantioselectivities (up to 95% ee).     

High-Power in-Band Pumped a-Cut Ho:Yap Laser

We report the continuous wave and acousto-optically Q-switched operation of an in-pumped a-cut Ho:YAP laser at room temperature. We obtained a continuous-wave output power of 17.2 W at 2118 nm under an absorbed pump power of 29.8 W, corresponding to a slope efficiency of 63.2 %. For the Q-switched mode, we achieved a maximum pulse energy of about 1.7 mJ and a minimum pulse width of 24 ns at a repetition rate of 10 kHz, resulting in a peak power of 70.8 kW.     

Evaluation and applications of a gaseous mercuric chloride source

In this study, a diffusion-type device for generating gaseous mercuric chloride (HgCl₂) was systematically evaluated and applied to validate the annular denuder method for sampling gaseous HgCl₂ species in a synthetic gas stream. The results show that it takes at least 48 h for the system to reach a steady-state condition after the diffusion cell reaches the temperature set-point and the carrier gas is activated. The primary Hg species from the source was proven to be HgCl₂. In the temperature range from –5.00 to 11.80 °C, the Hg emission rates from the source vary from 1.8 to 14.2 pg min^–1. It is shown that, under the experimental conditions examined, KCl-coated annular quartz denuders designed for ambient reactive gaseous mercury (RGM) collection could quantitatively collect HgCl₂. It is also demonstrated that the impactors used to remove coarse airborne particulate matter could lead to a loss of up to one third of the HgCl₂ in the gas stream.     

应用红外差谱技术测定二元混纺纤维的种类

应用傅立叶变换红外光谱测定六种二元混纺纤维,得到了清晰的红外光谱图,应用计算机差谱技术得到高质量的差谱结果,准确判明了混纺纤维的种类。本方法不需要对混纺纤维进行分离、预处理,制样简单、准确度好、操作简便。     

VCSEL with reticular electrode and larger emitting aperture and its optoelectronic characteristics

The enlargement of the emitting aperture is usually one of the important methods of increasing vertical- cavity surface-emitting laser （VCSEL） optical output power. However, in a VCSEL with a larger aperture, the inhomogeneity in the injected current often causes inhomogeneous or even no emission. To solve this problem and to increase VCSEL output power, as well as to improve its thermal characteristics, we develop a new type of injected VCSEL with a larger aperture and a reticular electrode, where the conventional circular injection electrode of the P side is turned into a reticular one, and the heat sink is on the N side. The tests of the new VCSEL show an improvement in homogeneity in not only the injected current but also the emission intensity. The optical output power is also considerably increased, and the device optoelectronic performance is improved.     

金、银纳米结构中的非局域吸收特性

采用时域有限差分方法（FDTD）研究金、银纳米结构的非局域吸收。对金属材料的Drude-Lorentz模型进行离散差分,详细推导各项迭代系数。研究一维、二维、三维金、银纳米结构的吸收特性。讨论一维分层纳米薄膜吸收率与材料的关系。结果表明：非局域分层介质板仍然符合等效介质理论。在一维、二维情况下,金、银纳米结构的非局域吸收峰只与纳米尺度相关而与材料无关。三维纳米结构的非局域吸收特性不仅与纳米尺度相关还与材料特性相关。三维纳米结构尺度更小,非局域效应表现也更为明显,吸收峰的蓝移也更大。因此,三维纳米颗粒有望在纳米材料以及纳米器件的研究中发挥更大的作用。     

Non-enzymatic sensing of hydrogen peroxide using a glassy carbon electrode modified with the layered MoS<Subscript>2</Subscript>-reduced graphene oxide and Prussian Blue

The authors describe an electrochemical sensor for hydrogen peroxide (H₂O₂). It was constructed by consecutive, selective modification of a glassy carbon electrode (GCE) with Prussian Blue (PB), layered molybdenum disulfide (MoS₂), and reduced graphene oxide (rGO). The properties of the modified GCE were characterized via high-resolution transmission electron microscopy, UV-vis spectroscopy and X-ray diffraction. The electrochemical properties of the electrode were studied using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrocatalytic activity for the reduction of hydrogen peroxide in comparison to GCEs modified with MoS₂-rGO or PB only. Response is linear in the 0.3 μM to 1.15 mM H₂O₂ concentration range at a working analytical voltage of 0.1 V, with a 0.14 μM detection limit. The electrochemical sensitivity is 2883.5 μA·μM^?1·cm^?2, and response is fast (<10 s). The sensor is selective, stable and reproducible. This is attributed to the efficient electron transport properties of the MoS₂-rGO composite and the high loading with PB.

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Graphic abstract Prussian Blue nanoparticles were deposited on MoS₂-rGO modified glassy carbon electrode by electrochemical method. This sensor was used for the detection of H₂O₂ in tap water and river water.

     

A tantalum electrode coated with graphene nanowalls for simultaneous voltammetric determination of dopamine,uric acid,L-tyrosine,and hydrochlorothiazide

The authors describe a voltammetric sensor for simultaneous determination of dopamine (DA), uric acid (UA), L-tyrosine (Tyr), and the diuretic drug hydrochlorothiazide (HCTZ). The assay is based on the use of graphene nanowalls deposited on a tantalum substrate. The nanowalls are characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, electrochemical impedance spectroscopy, and cyclic voltammetry. The nanowalls are vertically grown on the substrate by direct-current arc plasma jet chemical vapor deposition. The modified electrode is shown to enable simultaneous differential pulse voltammetric determination of DA, UA, Tyr, and HCTZ. The graphene nanowalls display a large specific surface, high conductivity, and a large number of catalytically active sites for oxidation of analytes. Simultaneous detection is performed best at a pH value of 7.0 and at peak potentials of 0.124 V (vs. SCE) for DA, 0.256 V for UA, 0.536 V for Tyr and 0.708 V for HCTZ. The respective detection limits are 0.04 μM, 0.1 μM, 0.6 μM and 0.4 μM. The results show that this graphene wall modified electrode is a promising tool for the design of sensitive, selective, and stable sensors.

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Graphical abstract The graphene-based differential pulse voltammetric sensor for simultaneous determination of dopamine, uric acid, L-tyrosine, and hydrochlorothiazide exhibits high selectivity, sensitivity, and stability.