Breaking the diffraction barrier: optical microscopy on a nanometric scale

In near-field scanning optical microscopy, a light source or detector with dimensions less than the wavelength (lambda) is placed in close proximity (lambda/50) to a sample to generate images with resolution better than the diffraction limit. A near-field probe has been developed that yields a resolution of approximately 12 nm ( approximately lambda/43) and signals approximately 10(4)- to 10(6)-fold larger than those reported previously. In addition, image contrast is demonstrated to be highly polarization dependent. With these probes, near-field microscopy appears poised to fulfill its promise by combining the power of optical characterization methods with nanometric spatial resolution.     

Aminoacyl-CoAs as probes of condensation domain selectivity in nonribosomal peptide synthesis

In nonribosomal biosynthesis of peptide antibiotics by multimodular synthetases, amino acid monomers are activated by the adenylation domains of the synthetase and loaded onto the adjacent carrier protein domains as thioesters, then the formation of peptide bonds and translocation of the growing chain are effected by the synthetase's condensation domains. Whether the condensation domains have any editing function has been unknown. Synthesis of aminoacyl-coenzyme A (CoA) molecules and direct enzymatic transfer of aminoacyl-phosphopantetheine to the carrier domains allow the adenylation domain editing function to be bypassed. This method was used to demonstrate that the first condensation domain of tyrocidine synthetase shows low selectivity at the donor residue (D-phenylalanine) and higher selectivity at the acceptor residue (L-proline) in the formation of the chain-initiating D-Phe-L-Pro dipeptidyl-enzyme intermediate.     

Microstructured optical fibers as high-pressure microfluidic reactors

Deposition of semiconductors and metals from chemical precursors onto planar substrates is a well-developed science and technology for microelectronics. Optical fibers are an established platform for both communications technology and fundamental research in photonics. Here, we describe a hybrid technology that integrates key aspects of both engineering disciplines, demonstrating the fabrication of tubes, solid nanowires, coaxial heterojunctions, and longitudinally patterned structures composed of metals, single-crystal semiconductors, and polycrystalline elemental or compound semiconductors within microstructured silica optical fibers. Because the optical fibers are constructed and the functional materials are chemically deposited in distinct and independent steps, the full design flexibilities of both platforms can now be exploited simultaneously for fiber-integrated optoelectronic materials and devices.     

单胞藻超滤浓缩技术研究与发展

综述了单胞藻各种浓缩方法——自然沉降法、化学浓缩方法和离心浓缩方法的研究概况,详细评述了近年来国内外采用超滤技术作为浓缩、分离过程的研究和应用进展,以及超滤作为膜分离技术已广泛应用于单胞藻浓缩领域的发展趋势。     

单胞藻超滤浓缩技术研究与发展

综述了单胞藻各种浓缩方法——自然沉降法、化学浓缩方法和离心浓缩方法的研究概况,详细评述了近年来国内外采用超滤技术作为浓缩、分离过程的研究和应用进展,以及超滤作为膜分离技术已广泛应用于单胞藻浓缩领域的发展趋势。     

N-酰基丙氨酸类杀菌剂光学纯度的色谱分析

报道了旋光性Ｎ－酰基丙氨酸类杀菌剂光学纯度的色谱分析方法。光学活性杀菌剂的合成中间体Ｎ－（２,６－二甲苯基）－丙氨酸与ｌ－薄荷醇在催化剂作用下,生成非对映异构体的薄荷醇酯。经薄层色谱纯化,用高效液相色谱进行分析,即可确定中间体的光学纯度。光学纯度一定的中间体经合成至最终产物,其光学纯度不变。     

Laser as light source for optical diffractometers; fourier analysis of electron micrographs

Fourier analysis of electron micrographs has been accomplished underptimum conditions with a gas laser as the light source for an optical diffractometer.     

高折射率环硫树脂镜片材料的制备与性能研究

以双酚A型环氧树脂(Epoxy resin,EP)和硫脲(Thiourea)为原料,制备出环硫树脂(Episulfide resin),再与双酚A型环氧树脂按一定比例混合制备出一系列环硫和环氧混合树脂(Episulfide&epoxy mixture resin),用于镜片树脂材料;同时利用红外光谱仪(IR)分析了环硫树脂的结构,用万能试验机测定了混合树脂的弯曲性能,用折射率仪和紫外可见分光光度计分别测定了混合树脂的折射率和透光性.结果表明,当m(环硫树脂)∶m(环氧树脂)1∶5时力学性能又有所改善,随着