Tunable Diode Laser Spectroscopy With Wavelength Modulation: A Phasor Decomposition Method for Calibration-Free Measurements of Gas Concentration and Pressure

The principles and implementation of a phasor decomposition method for analyzing signals in tunable diode laser spectroscopy with wavelength modulation are described. This new technique enables recovery of the isolated and normalized residual amplitude modulation (RAM) signal from measured first harmonic signals at any chosen fundamental modulation frequency. Like the previously reported RAM technique, this new approach is absolute, yielding gas absorption line shape functions, concentrations and pressures without the need for calibration, under certain defined operating conditions. It represents an advancement of the RAM technique in that it obviates the need to operate at a specific high frequency to achieve phase quadrature between the RAM and derivative signals: the signals may be recovered at their maximum levels at any frequency. Measurements of the 1650.96 nm and the 1666.2 nm rotation/vibration absorption line shape functions for 1% and 10% methane in nitrogen at various pressures are compared to theoretical predictions derived from HITRAN data. The excellent agreement confirms the validity of the new technique. Further measurements of concentration and pressure confirm the efficacy of the technique for determining concentration in industrial process environments where the pressure may be unknown and changing. With the above features this new method is particularly suited to stand alone instrumentation for on-line deployment in industrial processes where the calibration factors in the conventional approach would present significant difficulties.     

Surface-initiated growth of copper using isonicotinic acid-functionalized aluminum oxide surfaces

Isonicotinate self-assembled monolayers (SAM) were prepared on alumina surfaces (A) using isonicotinic acid (iNA). These functionalized layers (iNA-A) were used for the seeded growth of copper films (Cu-iNA-A) by hydrazine hydrate-initiated electroless deposition. The films were characterized by scanning electron microscopy (SEM), electron-dispersive X-ray spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and advancing contact angle measurements. The films are Cu⁰ but with surface oxidation, and show a faceted morphology, which is more textured (R _q = 460 ± 90 nm) compared to the SAM (R _q = 2.8 ± 0.5 nm). In contrast, growth of copper films by SnCl₂/PdCl₂ catalyzed electroless deposition, using formaldehyde (CH₂O) as the reducing agent, shows a nodular morphology on top of a relatively smooth surface. No copper films are observed in the absence of the isonicotinate SAM. The binding of Cu²⁺ to the iNA is proposed to facilitate reduction to Cu⁰ and create the seed for subsequent growth. The films show good adhesion to the functionalized surface.     

Cost of administering controlled drugs in a hospice ward

A study was undertaken in 1995 to examine the time taken to administer Controlled Drugs (CDs) in one of the two seven-bedded wards in the Prince and Princess of Wales Hospice (PPWH) in the course of one week. A stop watch was used to measure the time taken from the decision to give a CD until its administration was entered into the CD Register. The drugs used were oral morphine, oral sustained release morphine and diamorphine for subcutaneous administration by syringe driver. The grade of nurses involved in administering the CDs was also recorded. The time taken by D, E, F, and G grade nurses was extrapolated to the number of hours per annum spent administering the CDs. The hourly rate for the various grades was documented and the total cost calculated. The total annual cost of administering CDs to the seven patients in the study was calculated to be 10,883.94 pounds. The total cost for the two wards was extrapolated to 21,767.88 pounds. The annual cost of the CDs was 7,294.63 pounds. The total cost of the CDs and their administration was 29,062.51 pounds: 75% of the expenditure is the cost of administration. Syringe drivers cost twice as much to administer as sustained release morphine tablets.     

Dielectric spectroscopy of anaerobic adhesive cure

Dielectric spectroscopy (DS) is shown to be a most useful tool for the study of the surface initiated redox cure in model anaerobic acrylic adhesives. These models are deliberately designed to exhibit different levels of cure heterogeneity. The cure is initiated by the surfaces of two substrates on either side of a bondline. The heterogeneous cure situation is referred to as low cure through volume (CTV). Poor CTV is an undesirable feature that leads to mechanical weakness in an adhesive bond. Thus, experimental techniques based on DS are developed to investigate the cure characteristics and in particular the CTV phenomenon in the model anaerobic adhesives.     

Tunable Diode Laser Spectroscopy for Industrial Process Applications: System Characterization in Conventional and New Approaches

Tunable diode laser spectroscopy (TDLS) can only be successfully implemented if a number of system characterization procedures and critical parameter measurements can be made accurately. These include: application of a wavelength/frequency scale to the signals recovered in time; measurement of the frequency dither applied to the laser; measurement of the relative phase between the laser power modulation and frequency modulation; determination of the background amplitude modulation for normalization purposes and measurement of required cross broadening coefficients for the host/target gas mixtures. Easy to implement, accurate and low-cost systems and procedures for achieving these are described and validated below. They were developed for two new approaches to TDLS measurements, viz the residual amplitude modulation (RAM) technique and the phasor decomposition (PD) method, but are equally applicable to all forms of TDLS. Following full system characterization using the new techniques, measurements of the absolute transmission function of the 1650.96 nm absorption line of methane over a wide range of concentration and pressure were made using the RAM technique. The close agreement with theoretical traces derived from HITRAN data validated the entire approach taken, including the system characterization procedures. In addition, measurements of a wide range of gas concentration and pressure were made by curve fitting theoretical traces to the measured transmission functions obtained using a variety of operating conditions. Again, the low errors confirmed the validity of the new methods and the system characterization/measurement procedures described here.     

Characterization of model anaerobic adhesive cure using real-time fourier transform infrared spectroscopy and dielectric spectroscopy

A technique has been developed based on Fourier transform infrared spectroscopy (FTIR) in the attenuated total reflectance (ATR) mode, which is suitable for the investigation of the heterogeneous cure of surface-initiated redox polymerizations in thin and thick bondline situations. The results of the investigations into the surface-catalyzed and anaerobically promoted cure of some model adhesives using this method are reported. The systems under investigation were designed to exhibit different levels of cure heterogeneity or “cure through volume” (CTV) so that the influence of the bondline thickness and the formulation variables may be assessed. The analysis of the data provides evidence that supports our concept of the heterogeneous cure distribution existing in the form of a cure gradient. This concept of a cure gradient is developed further using dielectric spectroscopy. Here the cure gradient is characterized in terms of the parameters obtained using an empirical equation to fit the dielectric relaxation data. The results obtained using the infrared and dielectric spectroscopic methods are in satisfactory agreement and are shown to be most informative in characterizing and quantifying the CTV performance of the model anaerobic adhesives. © 1994 John Wiley & Sons, Inc.     

Glassy carbon manufacture using rapid photonic curing

Journal of Materials Science - Photonic curing was explored as a rapid method for producing glassy carbon coatings, reducing processing time from ~?20 h for conventional thermal...     

Food intake, milk production, and tissue changes of Holstein-Friesian and Jersey × Holstein-Friesian dairy cows within a medium-input grazing system and a high-input total confinement system

Although interest in crossbreeding within dairy systems has increased, the role of Jersey crossbred cows within high concentrate input systems has received little attention. This experiment was designed to examine the performance of Holstein-Friesian (HF) and Jersey × Holstein-Friesian (J × HF) cows within a high concentrate input total confinement system (CON) and a medium concentrate input grazing system (GRZ). Eighty spring-calving dairy cows were used in a 2 (cow genotype) × 2 (milk production system) factorial design experiment. The experiment commenced when cows calved and encompassed a full lactation. With GRZ, cows were offered diets containing grass silage and concentrates [70:30 dry matter (DM) ratio] until turnout, grazed grass plus 1.0 kg of concentrate/day during a 199-d grazing period, and grass silage and concentrates (75:25 DM ratio) following rehousing and until drying-off. With CON, cows were confined throughout the lactation and offered diets containing grass silage and concentrates (DM ratio; 40:60, 50:50, 40:40, and 75:25 during d 1 to 100, 101 to 200, 201 to 250, and 251 until drying-off, respectively). Full-lactation concentrate DM intakes were 791 and 2,905 kg/cow for systems GRZ and CON, respectively. Although HF cows had a higher lactation milk yield than J × HF cows, the latter produced milk with a higher fat and protein content, so that solids-corrected milk yield (SCM) was unaffected by genotype. Somatic cell score was higher with the J × HF cows. Throughout lactation, HF cows were on average 37 kg heavier than J × HF cows, whereas the J × HF cows had a higher body condition score. Within each system, food intake did not differ between genotypes, whereas full-lactation yields of milk, fat plus protein, and SCM were higher with CON than with GRZ. A significant genotype × environment interaction was observed for milk yield, and a trend was found for an interaction with SCM. Crossbred cows on CON gained more body condition than HF cows, and overall pregnancy rate was unaffected by either genotype or management system. In summary, milk and SCM yields were higher with CON than with GRZ, whereas genotype had no effect on SCM. However, HF cows exhibited a greater milk yield response and a trend toward a greater SCM yield response with increasing concentrate levels compared with the crossbred cows.