Gold‐Catalyzed Fluorination–Hydration: Synthesis of α‐Fluorobenzofuranones from 2‐Alkynylphenol Derivatives

The Au^I‐catalyzed fluorination–hydration of 2‐alkynylphenol derivatives in the presence of Selectfluor [1‐chloromethyl‐4‐fluoro‐1,4‐diazoniabicyclo‐[2.2.2]octane bis(tetrafluoroborate)] has been developed. This method provides straightforward access to α‐fluorobenzofuranones with the construction of C?O, C=O, and C?F bonds in a single step on the basis of an Au^I/Au^III redox catalytic cycle. Several control experiments, including the asymmetric variant of this reaction, were also conducted to gain insight into the reaction mechanism.     

Synthesis and Insecticidal Activities of Chlorothiazolyl Analogs of Nitromethylene Neonicotinoids with Tetrahydropyridine Fixed cis‐Configuration

The chlorothiazolyl moiety was an effective bioisoster of chloropyridyl in pesticide molecular design. Replacement of chloropyridyl in cis‐nitromethylene neonicotinoids with chlorothiazolyl generated the chlorothiazolyl counterpart of nitromethylene neonicotinoids with tetrahydropyridine fixed cis‐configuration. Bioassay against cowpea aphis (Aphis craccivora) indicated that the chlorothiazolyl analogs could maintain the high insecticidal activity.     

The roles of cysteines in the heme domain of human soluble guanylate cyclase

Soluble guanylate cyclase(sGC) is a critical heme-containing enzyme involved in NO signaling.The dimerization of sGC subunits is necessary for its bioactivity and its mechanism is a striking and an indistinct issue.The roles of heme domain cysteines of the sGC on the dimerization and heme binding were investigated herein.The site-directed mutations of three conserved cysteines(C78A,C122A and C174S) were studied systematically and the three mutants were characterized by gel filtration analysis,UV-vis spectroscopy and heme transfer examination.Cys78 was involved in heme binding but not referred to the dimerization,while Cys174 was demonstrated to be involved in the homodimerization.These results provide new insights into the cysteine-related dimerization regulation of sGC.     

Cold crystallization behavior of polyamide 6 in PS‐g‐PA6 graft copolymers

TEM micrographs show that the PA grafts of PS‐g‐PA6 graft copolymers, which are obtained directly by extracting homo‐PA6 out from the homo‐PA6/PS‐g‐PA6 blends, are in the form of wormlike structure. The wormlike PA6 domains can shrink into droplets after annealing at 250 °C for 15 min. The diameter of the droplet determined by TEM and SAXS is in the range of 50–60 nm. This article reports on a unique crystallization behavior of the PA6 grafts in PS‐g‐PA6 graft copolymers. In a DSC cooling scan, PA6 grafts do not crystallize from the melt with a cooling rate of 10 °C/min. However, there is a cold crystallization peak around 65 °C in the subsequent heating scan. This cold crystallization phenomenon, which has not yet been reported in the literature till now, follows well the homogeneous nucleation mechanism and is depressed at relatively slow cooling rates (2 °C/min) or even completely eliminated after annealing within a specific temperature range. It may be caused by the slow diffusion or transport rate of the less flexible PA6 grafts to the crystal fronts when crystallization takes place around its glass transition temperature. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 65–73, 2010     

Synthesis of novel chiral oxazoline-Schiff base ligands for the catalytic asymmetric chlorination of β-keto esters

A series of novel monooxazoline-Schiff base ligands 1 has been successfully synthesized. The Cu(I)–1a complex showed excellent catalytic activities with up to 83% ee for the asymmetric α-chlorination of β-keto esters.     

自制三种物理实验装置及演示

1演示超重现象 取透明塑料瓶一个，截去瓶底，并改用一张白纸封住底部（可用细线捆扎）．再取一段橡皮筋，一端和一柱形金属重物连结，并将重物放入瓶中，橡皮筋另一端固定在瓶口处．静止时重物不和白纸接触，约保持1cm距离．整个装置如图1所示．     

Beam focusing through a tapered subwavelength aperture surrounded by dielectric surface gratings

A novel plasmonic nanolens formed by a tapered subwavelength metal slit surrounded by surface dielectric gratings is proposed and demonstrated numerically. By patterning surface corrugations on the output surface, the beam can be focused, by regulating the aperture, the focal length can be controlled effectively. Numerical simulations using Finite-Difference Time-Domain (FDTD) method coupled with anisotropic perfectly matched layer (APML) boundary conditions verify that the proposed metallic lens can focus the radiation on the scale of a wavelength below the substrate and the method is effective for the design of nano-optical devices such as optical microprobes.     

Local field enhancement of pair arrays of silver nanospheres

Local field surface plasmon excitation of pair arrays of silver nanospheres was studied using three-dimensional finite-difference time-domain method. The near-field enhancement was associated with the radius of nanosphere and the incident wavelength, the highest of which always appeared in the penultimate gaps, regardless of the number of the pairs. The surface plasmon resonance could be controlled and tuned by radius of nanosphere and incident wavelength.     

Grain size of nanocrystalline YSZ buffer layers fabricated by ion beam deposition

Amorphous or nanocrystalline thin films are capable to be efficient diffusion barrier layers for YBCO coated conductors of ion beam assisted deposition route. Nanocrystalline Yttria-Stabilized Zirconia (YSZ) buffer layers were fabricated by the ion beam deposition. Kr and Ar gases were utilized for the dual Kaufman type sputtering ion sources sequently. Both of the ion beams were fixed at 200 mA, while the ion energy was in the range of 450–2000 eV. The thickness of the YSZ buffer layers was several hundreds of nanometers. The grain size of YSZ thin films, which varied from 2 to 20 nm, was calculated by Scherrer Formulation based on the X-ray diffraction measurement results. The grain size always decreased at first and then increased when the ion energy was increased. In the cases Kr gas was utilized and Ar gas was utilized, the grain size reached its minimum value at the ion energy of about 1800 eV and 1000 eV, respectively. Such phenomenon was discussed using the thermodynamic theory of thin film nucleation. Deposition rate and substrate temperature were the two chief variables of the critical nuclei concentration and grain size.