Preparation pulse 660 INDEX

A wide linear response range and high flow rate capability, are desirable features in a detector for preparative-scale chromatography. Problems with temperature stability (refractive index) and pressure pulses (UV detector) are less important because of the high sample concentrations present in the mobile phase. Some analytical detectors have interchangeable flow cells, which allow replacement of the analytical cell with one of... 

With this much interest in polyethylene, many attempts have been made to use low frequency NMR in either the time domain or frequency domain to monitor and control the production more rapidly. Auburn International (now part of Oxford Instruments) developed a widely adopted system based on the time domain spectrometers [21]. In this case, sample preparation is no longer an issue since the system accepts either powder or pellets and no solvent is used. The Auburn systems determine crystalline and amorphous ratios, viscosity, melt index and molecular weight For other types of polymers, the list of advertised measurements include tacticity, rubber content, copolymer analysis, and various rheological properties. These values are determined by correlating several routine but laborious methods with the decay of the NMR signal under various pulse sequences. The man-hours... 

It is well known that high-quality three-dimensional photonic stmctures, e.g., buried chaimel waveguides, which can be used for laser emissions, have been readily created on transparent laser ceramics, by using irradiations of short-pulse lasers [263-271] and particle beams [272—278]. This process is based on the controlled modification of the refractive index of the electronic processes and thermally induced transformations associated with laser irradiation. Laser writing to create such structures is a one-step process without the requirement of special preparation. It is a very fast, highly reproductive, and thus low-cost process. It has been employed to fabricate various integrated photonic devices. 

Hu et al. [131] used optical transmission to measure the optical functions of thin-film ZnO prepared by pulsed laser deposition on a-Si02 substrates. The ordinary refractive indices deduced from transmittance oscillations were 0.02-0.03 lower than the bulk ZnO crystal data by Bond [11]. The existence of grain boundaries in the films was assumed to be the source for this difference. In addition, the measurement technique introduced a considerably large error resulting in large variations in the data. The best fits for the ordinary index using the three-term Cauchy equation,... 

The output waveforms that passed through the two typ>es of GI POFs, prepared by the rod-in-tube method and the interfadal-gel polymerization technique, respectively, are shown in Figure 13. Even though both fibers have similar refractive index coeffidents, which is approximated to eqn [4] by using a least-square method, the output pulse of the GI POF prepared by the rod-in-tube method is much narrower than that of the fiber prepared by the interfadal-gd polymerization technique. Figure 14 represents the -3 dB bandwidth of these GI POFs with various index coeffidents. The GI POFs prepared by the intetfadal-gel polymerization method show good agreement with the theoretical value. On the other hand, the bandwidth of the Gl POF prepared by the rod-in-tube method deviates upward from the theoretical line. Based on the calculations, the bandwidth of a GI POF with a refractive index coeffident of 6.0 should be 620 MHz, but the fiber actually exhibits a bandwidth of 4.8 GHz. 

---