Comparison of urinary excretion of UV-absorbing constituents in healthy subjects and patients with rheumatoid arthritis using analytical isotachophoresis

Analytical isotachophoresis has been applied to the separation of urinary constituents in healthy controls and patients with rheumatoid and osteoarthritis. Various methods of comparing isotachograms have been investigated. Significant differences have been demonstrated between the pattern of UV-absorbing components in patients with rheumatoid arthritis and healthy subjects.     

Application of Balanced Detection to Absorption Measurements of Trace Gases with Room-Temperature, Quasi-cw Quantum-Cascade Lasers

Distributed-feedback quantum-cascade (QC) lasers are expected to form the heart of the next-generation mid-IR laser absorption spectrometers, especially as they are applied to measurements of trace gases in a variety of environments. The incorporation of room-temperature-operable, single-mode QC lasers should result in highly compact and rugged sensors for real-world applications. We report preliminary results on the performance of a laser absorption spectrometer that uses a QC laser operating at room temperature in a quasi-cw mode in conjunction with balanced ratiometric detection. We have demonstrated sensitivities for N(2)O [10 parts in 10(6) volume-mixing ratio for a 1-m path (ppmv-m)] and NO [520 parts in 10(9) volume-mixing ratio for a 1-m path (ppbv-m)] at 5.4 mum. System improvements are described that are expected to result in a 2 orders of magnitude increase in sensitivity.     

Cavity ringdown spectroscopic detection of nitric oxide with a continuous-wave quantum-cascade laser

A spectroscopic gas sensor for nitric oxide (NO) detection based on a cavity ringdown technique was designed and evaluated. A cw quantum-cascade distributed-feedback laser operating at 5.2 mum was used as a tunable single-frequency light source. Both laser-frequency tuning and abrupt interruptions of the laser radiation were performed through manipulation of the laser current. A single ringdown event sensitivity to absorption of 2.2 x 10(-8) cm(-1) was achieved. Measurements of parts per billion (ppb) NO concentrations in N(2) with a 0.7-ppb standard error for a data collection time of 8 s have been performed. Future improvements are discussed that would allow quantification of NO in human breath.     

A cost and performance comparison of LRTM and VI for the manufacture of large scale wind turbine blades

Light resin transfer moulding (LRTM) has been developed as an alternative to vacuum infusion (VI) but a direct comparison between the two processes is needed to quantify any advantages. This paper uses a technical cost model and an empirical study to show the potential financial and performance benefits of LRTM for manufacture of a generic 40 m wind turbine blade shell. The use of LRTM when compared to VI demonstrated a possible 3% cost saving, improved dimensional stability (5.5%), and reductions in resin wastage (3%) and infusion time (25%). A decrease in internal void formation (0.9%) resulted in an increase in mechanical performance (<4%) for LRTM moulded parts.     

CIB organizations

G.L. Hutchinson, Reader in Civil Engineering, University of Melbourne and John L. Wilson, formerly State Electricity Commission of Victoria, Melbourne, now of Ove Arup &; Partners, London, examine the design of typical medium‐rise steel‐framed industrial buildings. Such buildings usually possess a non‐uniform distribution of mass and stiffness and consequently respond in more than one mode under earthquake excitation, thus making the application of Article 16 of the Chinese Earthquake Code appropriate     

Heat generation during the fatigue of a cellular Al alloy

The heat generation from a notch during the compression-compression fatigue of a cellular Al alloy has been measured and compared with a model. The measurements indicate that heat is generated because of hysteresis occurring in narrow cyclic plastic zones outside the notch. This process continues until the notch closes. At closure, a brief period of heat generation arises because of friction along the notch faces. A plasticity model based on the Dugdale zone is shown to provide a reasonably accurate characterization of the heat generated, with the proviso that an “ineffective” zone be transposed onto the notch tip. It is found that the temperatures generated are too small to cause fatigue by thermal softening. A fatigue mechanism based on either geometric softening of the cells or crack growth in the cell walls is implied.