A study of J-coupling spectroscopy using the Earth's field nuclear magnetic resonance inside a laboratory

In this paper, an instrumentation of the Earth's field nuclear magnetic resonance (EFNMR) inside a laboratory is presented. A lock-in analysis (LIA) technique was proposed to enhance the signal-to-noise ratio (SNR). A SNR of 137.8 was achieved in a single measurement for 9 ml tap water, and the LIA technique significantly enhanced the SNR to 188 after a 10-average in a noisy laboratory environment. The proton-phosphorus coupling in trimethyl phosphate ((CH(3)O)(3)PO) with J-coupling J[H,F]=(10.99±0.013)?Hz has been demonstrated. The LIA technique improves the SNR, and a 2.6-fold improvement in SNR over that of the frequency-adjusted averaging is achieved. To reduce the noise in EFNMR, it was suggested that the LIA technique and the first order gradient shim be used to achieve a subhertz linewidth.     

Biosynthesis of nanocrystal akaganéite from FeCl2 solution oxidized by Acidithiobacillus ferrooxidans cells

Akaganéite (beta-FeOOH) is a major iron oxyhydroxide component in some soils, marine concretions, and acid mine drainage environments. Recently, synthetic beta-FeOOH has been found to be a promising absorbent in the treatment of metal-contaminated water. It has been recognized in previous study that akaganéite could be formed via FeCl2 chemical oxidation under specific conditions. Here we report a novel and simple method for akaganéite bioformation from FeCl2 solution oxidized by Acidithiobacillus ferrooxidans LX5 cells at 28 degrees C. After acclimation in modified 9K medium containing 0.2 M chloride, Acidithiobacillus ferrooxidans cells had great potential for oxidization of Fe2+ as FeCl2 solution, and then resulted in the formation of precipitates. The resulting precipitates were identified by powder X-ray diffraction and transmission FT-IR analyses to be akaganéite. Scanning electron microscopy images showed the akaganéite was spindle-shaped, approximately 200 nm long with an axial ratio of about 5, and the spindles had a rough surface. X-ray energy-dispersive spectral analyses indicated the chemical formula of the crystalloid akaganéite could be expressed as Fe8O8(OH)7.1(Cl)0.9 with Fe/Cl molar ratio of 8.93. The biogenetic akaganéite had a specific surface area of about 100 m2 g(-1) determined by BET method.     

电雷管感度分类的模糊模式识别方法

电雷管发火感度的一致性是工程爆破中实现串联齐爆的关键.针对感度不能精确测量的问题,对以电热响应原理为基础的无损检测技术测得的特征参数进行分析,利用模糊数学手段,找到一种建立产品感度模糊模式的方法.通过模糊模式识别可将产品按感度分类,同类感度的电雷管串联齐爆的可靠性明显提高.     

New fast algorithm for 2-D Angle-Of-Arrival estimation

Based on propagator method, a fast 2-D Angle-Of-Arrival （AOA） algorithm is proposed in this paper. The proposed algorithm does not need the Eigen-Value Decomposition （EVD） or Singular Value Decomposition （SVD） of the Sample Covariance Matrix （SCM）, thus the fast algorithm has lower computational complexity with insignificant performance degradation when comparing with conventional subspace approaches. Furthermore, the proposed algorithm has no performance degradation. Finally, computer simulations verify the effectiveness of the proposed algorithm.     

An efficient total synthesis of a potent anti-inflammatory agent, benzocamphorin f, and its anti-inflammatory activity

A naturally occurring enynyl-benzenoid, benzocamphorin F (1), from the edible fungus Taiwanofungus camphoratus (Antrodia camphorata) was characterized by comprehensive spectral analysis. It displays anti-inflammatory bioactivity and is valuable for further biological studies. The present study is the first total synthesis of benzocamphorin F and the developed strategy described is a more efficient procedure that allowe the large-scale production of benzocamphorin F for further research of the biological activity both in vitro and in vivo.     

Sodium Sulfinate‐Mediated trans‐Stilbene Formation from Benzylic Halides

A convenient and efficient method for the synthesis of various symmetrical and non‐symmetrical trans‐stilbene derivatives from benzylic halides in the absence of any transition metals is described. Sodium sulfinates played an important role in this transformation. Various functional groups were well tolerated under the optimized reaction conditions.     

Asymmetric Counteranion‐Directed Iron Catalysis: A Highly Enantioselective Sulfoxidation

A highly active and enantioselective ion‐pair sulfoxidation catalyst, consisting of an achiral iron(III)‐salen cation and a chiral phosphate counteranion, mediates the oxidization of various sulfides with high yields and enantioselectivities. The enantioselectivities observed, especially for electron‐poor substrates, represent the best results so far in manganese and iron‐salen systems. This work represents the first application of our concept of asymmetric counteranion‐directed catalysis (ACDC) to iron catalysis.     

Fabrication of a form- and size-variable microcellular-polymer-stabilized metal nanocomposite using supercritical foaming and impregnation for catalytic hydrogenation

ABSTRACT: This article presents the fabrication of size-controllable and shape-flexible microcellular high-density polyethylene-stabilized palladium nanoparticles (Pd/m-HDPE) using supercritical foaming, followed by supercritical impregnation. These nanomaterials are investigated for use as heterogeneous hydrogenation catalysts of biphenyls in supercritical carbon dioxide with no significant surface and inner mass transfer resistance. The morphology of the Pd/m-HDPE is examined using scanning electron microscopy images of the pores inside Pd/m-HDPE catalysts and transmission electron microscopy images of the Pd particles confined in an HDPE structure. This nanocomposite simplifies industrial design and operation. These Pd/m-HDPE catalysts can be recycled easily and reused without complex recovery and cleaning procedures.     

高压断路器液（气）压操作机构常见故障处理

分析了高压断路器液（气）压操作机构常见的几种故障原因,指出缺陷处理过程中应注意的问题,介绍了断路器操作机构故障时的检查和处理方法。