Gradient‐enhanced one‐dimensional pulse schemes for quaternary and methylene carbon detection

Gradient‐enhanced pulse schemes are presented for the detection of quaternary and methylene carbons. The new pulse schemes permit the detection of quaternary and methylene (—CH₂) carbons or CH₂ carbons alone from a single experiment. Efficient suppression of CH and CH₃ carbons in all the pulse schemes is achieved by creating their antiphase magnetization and then dephasing using gradients. In the pulse schemes for detection of only CH₂ carbons, the quaternary carbons are also suppressed either by dephasing using gradients or by rendering them unobservable by retaining in longitudinal order. The experimental results of the gradient pulse schemes are demonstrated on cholesteryl acetate and cyclosporin A. These one‐dimensional techniques, because of their simplicity and the ease of performing the experiments, can be important for routine chemical applications. Copyright © 2003 John Wiley & Sons, Ltd.     

On the tribological characteristics of dynamically loaded journal bearing with micropolar fluids

The addition of the additives to the lubricant oil to enhance the characteristics of the lubricant will influence the performance of the bearings. Based on the theory of micropolar fluids, the tribological characteristics of a dynamically-loaded journal bearing are numerically studied. Comparisons are made between the Newtonian fluids and the micropolar fluids. It is shown that for a dynamically-loaded journal bearing, the micropolar fluids yield an increase not only in the friction force, but also in the friction coefficient. In addition, the oil film pressure and the oil film thickness are obviously higher than that of Newtonian fluids.     

受迫振动演示实验装置

本文叙述用示波器显示来演示受迫振动的实验装置，可直观地向学生展示受迫振动的幅频特性和相频特性。     

掺Perylene的PVK薄膜荧光谱及发光机理

用高荧光效率的有机染料芘(perylene)掺杂聚乙烯咔唑(PVK),其荧光光谱与芘的发射光谱基本一致,而且亮度比纯芘发光提高十多倍,说明发光主要来自芘分子,并在PVK和perylene之间存在十分有效的能量传递或电荷转移过程,荧光谱强度随掺杂浓度的变化关系说明存在一个最佳的掺杂浓度比.分析PVK和perylene之间可能发生的能量转移过程,认为从PVK到perylene这种能量转移与实验不符;分析PVK和perylene薄膜的光致发光过程,认为从(PVK+)→(perylene+)和从(PVK-)→(p     

ARL 9800XP型X射线荧光光谱仪的故障及维修

介绍了一例ARL-9800X射线荧光光谱仪的故障及故障排除的措施。     

Synthesis and optical properties of tetraphenylmethane-based tetrahedral fluorescent compounds and their water-soluble PEG-linked polymers

The synthesis and optical properties of tetrahedral fluorescent compounds comprising of tetraphenylmethane as the core and oligothiophenes as the chromophoric arms, and their water-soluble poly(ethylene glycol)-linked polymers are reported.     

Spectral Analysis of Powers of the Operator (Vf)(x)=q(x)∫0 xw(t)f(t),dt

Mathematical Notes -     

Polarization Sensitive Spectral Interferometric Optical Coherence Tomography for Biological Samples

A spectral interferometric optical coherence tomography (OCT) system which has polarization sensitivity is developed. This system reduces the mechanical scanning dimension by employing the principle of spectral interferometry, and measures a two dimensional cross-sectional image of biological tissue with one dimensional mechanical scanning. Sixteen OCT images with different polarization conditions are measured, and two dimensional distributions of each element of the Müller matrix of a sample to be measured are calculated.