Corrosion control methods in supercritical water oxidation and gasification processes

Use of supercritical water (SCW) as a medium for oxidation reactions, conversion of organic materials to gaseous or liquid products, and for organic and inorganic synthesis processes, has been the subject of extensive research, development, and some commercial activity for over 25 years. A key aspect of the technology concerns the identification of materials, component designs, and operating techniques suitable for handling the moderately high temperatures and pressures and aggressive environments present in many SCW processes. Depending upon the particular application, or upon the particular location within a single process, the SCW process environment may be oxidizing, reducing, acidic, basic, nonionic, or highly ionic. Thus, it is difficult to find any one material or design that can withstand the effects of all feed types under all conditions. Nevertheless, several approaches have been developed to allow successful continuous processing with sufficient corrosion resistance for an acceptable period of time. The present paper reviews the experience to date for methods of corrosion control in the two most prevalent SCW processing applications: supercritical water oxidation (SCWO) and supercritical water gasification (SCWG).     

A prospective analysis of the accuracy of the TEST-yolk buffer enhanced hamster egg penetration test and acrosin activity in discriminating fertile from infertile males

The aim of this study, based on a prospective analysis, was to evaluate the accuracy of the TEST-yolk buffer enhanced hamster egg penetration test (HEPT) and acrosin activity in discriminating fertile from infertile males as compared with the conventional semen profile. The incidence of spontaneous pregnancies was monitored during a follow-up period ranging between 18-24 months in 62 couples without untreatable female infertility. The diagnostic accuracy of the HEPT was significantly higher than that of the conventional semen profile, as evaluated with fitted ROC curves. The best discriminatory ability was exhibited by a penetration index (penetrations/oocyte) of 2 as cut-off value. In our series it gave a positive predictive value of 77.8% and a negative predictive value of 92.3%. Acrosin activity did not show a discriminating power significantly higher than the conventional semen profile, but an acrosin activity <20 microIU/10(6) spermatozoa was found only among patients who did not achieve a pregnancy. In conclusion, this prospective analysis indicates that the TEST-yolk buffer enhanced HEPT constitutes a significant improvement over the conventional semen profile in discriminating fertile from infertile males. Acrosin activity could provide a useful adjunctive test because of the high negative predictive value of its poor results.     

Analysis of input-polarization-induced phase noise ininterferometric fiber-optic sensors and its reduction using polarizationscrambling

The dependence of the phase shift of an interferometric fiber sensor on the input state of polarization is analyzed, and it is shown that fluctuations in the input polarization to a fiber interferometer can lead to the generation of excess phase noise. The relationship between this effect and the variation in visibility with input polarization is described and theoretically confirmed. The use of depolarized source light to eliminate input-polarization-induced excess phase noise is theoretically and experimentally demonstrated     

Polarisation-holding in a high-birefringence fibre

The polarisation-holding ability of a 1 km length of high-birefringence fibre is reported. The fibre birefringence increases linearly with frequency and the polarisation-holding parameter h is independent of frequency with a value of 5.5 × 10?6 m?1, indicating average polarisation-holding to ?22 dB.     

Probing the kinetics of SYTOX Orange stain binding to double-stranded DNA with implications for DNA analysis

Rapid binding kinetics of SYTOX Orange stain with double-stranded DNA (dsDNA) was revealed on the DNA fragment sizing flow cytometer. We demonstrated for the first time that the dye molecules could be adsorbed onto the capillary surface and native DNA fragments can be dynamically stained while passing through the capillary. High-quality burst size distribution histograms were obtained for DNA samples analyzed immediately after staining, dilution, or mixing. These observations indicated that rapid interactions exist between SYTOX Orange dye molecules and dsDNA. A stopped-flow fluorescence apparatus was set up to capture the fast association traces of intercalating dyes binding to dsDNA. Kinetic equations were derived to fit the association curves for determination of association rates and to model the dynamic staining, dilution, and mixing processes of DNA samples stained with intercalating dyes. The measured association rates for both SYTOX Orange and PicoGreen stains intercalating into dsDNA were on the order of 10(8) M-1 s-1, suggesting a diffusion-controlled process. Simulations indicate that reequilibration can be reached in seconds upon staining, dilution, or mixing. Insight into the kinetics of DNA binding dyes will help implement efficient sample-handling practices in DNA analysis, including DNA fragment sizing flow cytometry.     

Polarization properties of birefringent fibers with stress rods in the cladding

The polarization properties of fibers with high-expansion aluminum-doped stress rods in the cladding are described. Polarization beat lengths and polarization-holding parameters comparable to those of state-of-the-art high-birefringence fibers are obtained. The diameter of the outer cladding is not sufficient to provide optimum constraint on the stress rods. Increasing the diameter of this region should significantly reduce both the beat length and the polarization-holdingh- parameter. No anomalous behavior or thermal hysteresis is observed in the temperature dependence of the fiber birefringence below 600°C. Above 600°C, a permanent hysteresis which reduces the fiber birefringence is observed.     

Visibility limits in fibre-optic Michelson interferometer with birefringence compensation

The operation of a polarisation-insensitive fibre optic Michelson interferometer is further analysed. In particular, details are reported of an investigation of the limits in interference fringe visibility of the system due to offsets in the rotation angle of the Faraday elements used to effect the birefringence compensation.<>     

Polarization holding in elliptical-core birefringent fibers

Polarization holding in high-birefringence elliptical-core fibers is evaluated for the fiber birefringence spatial frequency range 1.5 cm^-1< beta_{i} < 40cm^-1, corresponding to beat lengths from 1.6 mm to 4.2 cm. This range of spatial frequencies is spanned by making measurements with a broad-band light source on four fibers with different degrees of birefringence. In this way, the strength of the internal birefringence perturbations is mapped to give the first experimental measure of their power spectrum. It is shown that commonly available fiber jackets can significantly degrade the polarization holding. For low spatial frequencies, the strength of the perturbations decreases rapidly with increasing frequency, but this rate decreases by more than half over a one-and-a-half order of magnitude increase in spatial frequency. A possible origin of the perturbations is suggested and it is shown that the strength of these perturbations must be reduced if polarization holding to a very high degree is to be realized in elliptical-core fibers. Presently, internal perturbations limit the polarization holding to ≤ 14.4 dB over 1 km.