The far infra-red spectrum of poly(vinyl chloride)

The far infra-red spectrum of a poly(vinyl chloride) sample prepared by the urea clathrate (UC) route has been measured at various temperatures in the range 60 to 320 K. The results, taken in conjunction with those for two less highly ordered polymers, indicate that a revision of the assignments of earlier workers, based on normal coordinate calculations and on the measured spectra of secondary alkyl chlorides such as 2-chlorobutane, is required. The band at 65 cm^?1 is attributed to a lattice mode and is not indicative of weak hydrogen bonds of the type CH…ClC. However, it is suggested that the band at 185 cm^?1, which is particularly clear and sharp with the UC polymer, probably originates from an interaction of this type, occurring specifically at tight chain folds.     

Dynamic modelling and analysis of post-combustion CO2 chemical absorption process for coal-fired power plants

Post-combustion capture by chemical absorption using MEA solvent remains the only commercial technology for large scale CO₂ capture for coal-fired power plants. This paper presents a study of the dynamic responses of a post-combustion CO₂ capture plant by modelling and simulation. Such a plant consists mainly of the absorber (where CO₂ is chemically absorbed) and the regenerator (where the chemical solvent is regenerated). Model development and validation are described followed by dynamic analysis of the absorber and regenerator columns linked together with recycle. The gPROMS (Process Systems Enterprise Ltd.) advanced process modelling environment has been used to implement the proposed work. The study gives insights into the operation of the absorber-regenerator combination with possible disturbances arising from integrated operation with a power generation plant. It is shown that the performance of the absorber is more sensitive to the molar L/G ratio than the actual flow rates of the liquid solvent and flue gas. In addition, the importance of appropriate water balance in the absorber column is shown. A step change of the reboiler duty indicates a slow response. A case involving the combination of two fundamental CO₂ capture technologies (the partial oxyfuel mode in the furnace and the post-combustion solvent scrubbing) is studied. The flue gas composition was altered to mimic that observed with the combination. There was an initial sharp decrease in CO₂ absorption level which may not be observed in steady-state simulations.     

Fouling control of a membrane coupled photocatalytic process treating greywater

Fouling in membrane coupled photocatalytic reactors was investigated in the case of greywater treatment by establishing the link between product type, dose, irradiation time and fouling rates in a cross flow membrane cell fitted with a 0.4 μm pore sized polyethylene membrane. Rapid fouling occurred only with shower gels and conditioners and was linked to changes in the organo-TiO₂ aggregate size postulated to be caused by polymers within the products. Fouling was reduced to a negligible level when sufficient irradiation was applied demonstrating that the membrane component of the process is not the issue and that scale up and implementation of the process relates to effective design of the UV reactor.     

Microwave measurements for seniors: applications of computer-basedinstruction

The integration of computer-based instruction with advanced, automated instrumentation, making use of the automated system's capability for individualized, self-paced tutoring in its own operation, is discussed. Details are presented on two such computer-based tutorials: one to provide an introduction to a microwave vector network analyzer, and the other to train students in the operation of a spectrum analyzer. The technique has broad potential for use in systems of PC instruments, and as an instructional tool for industry as well as academia     

High-Performance Switched Reluctance Brushless Drives

Switched reluctance (SR) drives offer the advantages of simple and robust motor construction, high speeds, high overall efficiencies over a wide operating range of torque and speed, simple power converter circuits with a reduced number of switches, and excellent controllability. The basis of these claims is explained. The history of the SR system, in particular the extensive research at Nottingham and Leeds Universities, and the basic operating principles and design considerations for motors and power converters are reviewed. Alternative configurations are discussed. The difficulties of establishing a simple mathematical model for the motor and of calculating torque and inverter VA requirements are examined. A comparison of the VA requirements for SR and pulsewidth modulation (PWM) is given for a 7.85-kW system. Measured drive performance is discussed in terms of efficiency over an operating envelope, specific output, controllability, and power converter ratings. Earlier traction drives, incorporating a constant power range and including regeneration, are reported together with the constant torque industrial drives and more recent traction extensions. The long-term potential of the drive is discussed for a wide range of applications. A comprehensive list of references is provided.     

Oligonucleotide mixture analysis via electrospray and ion/ion reactions in a quadrupole ion trap

Electrospray ionization combined with ion/ion reactions in a quadrupole ion trap can be used for the direct analysis of oligonucleotide mixtures. Elements to the success of this approach include factors related to ionization, ion/ion reactions, and mass analysis. This paper deals with issues regarding the ion polarity combination, viz., positive oligonucleotides/negative charge-transfer agent versus negative oligonucleotides/positive charge-transfer agent. Anions derived from perfluorocarbons appear to be directly applicable to mixtures of positive ions derived from electrospray of oligonucleotides, in direct analogy with positive protein ions. Conditions for forming positive oligonucleotide ions devoid of adducts were more difficult to establish than for forming relatively clean negative oligonucleotide ions. A new approach for manipulating negative ion charge states in the ion trap is described and is based on use of the electric field of the positive charge-transfer agent for storage of high-mass negative ions formed during the ion/ion reaction period. Oxygen cations are shown to be acceptable for charge-state manipulation of mixed-base oligomers but induce fragmentation in polyadenylate homopolymers. Protonated isobutylene (C4H9+), on the other hand, is shown to induce significantly less fragmentation of polyadenylate homopolymers.     

Monospecific antibodies as probes for the stoichiometry of recombinant GABA(A) receptors

GABA(A) receptors composed of alpha1beta3 gamma2 and alpha1beta3 subunits were expressed in insect Sf9 cells and solubilized in 1% Triton X100. In sucrose density gradients, [3H]-Ro15-1788 binding activity, in the case of alpha1beta3 gamma2, and [3H]-muscimol binding activity, in the case of alpha1beta3 containing receptors sedimented as a single sharp peak suggesting the formation of receptors containing a defined number of subunits. When alpha1beta3gamma2 -containing receptors were incubated with an alpha-subunit specific antibody (bd24), a single class of antibody receptor complex was formed irrespective of the receptor-antibody ratio. This is consistent with two alpha subunits cross-linked within the receptor by the antibody. Similar results were obtained using a beta-subunit specific antibody (bd17). Several classes of antibody-receptor complex were formed when receptors were pre-incubated with a gamma specific antibody (anti gamma(2) 1-15 Cys). This profile is consistent with the presence of a single gamma subunit in each complex. Experiments with alpha1beta3 subunit containing receptors and antibody bd24 produced a profile similar to that seen with alpha1beta3 gamma2 receptors, consistent with two alpha subunits per receptor complex. In this case, the anti-beta subunit antibody, bd17, produced a unique and complex profile consistent with three beta subunits per receptor. This method permits the rapid determination of subunit stoichiometries of homogeneous receptor populations     

Ion trap collisional activation of the (M + 2H)2+ - (M + 17H)17+ ions of human hemoglobin beta-chain

The parent ions of human hemoglobin beta-chain ranging in charge from 2+ to 17+ have been subjected to ion trap collisional activation. The highest charge-state ions (17+ to 13+) yielded series of products arising from dissociation of adjacent residues. The intermediate charge-state ions (12+ to 5+) tended to fragment preferentially at the N-terminal sides of proline residues and the C-terminal sides of acidic residues. Many, but not all, of the possible cleavages at proline, aspartic acid, and glutamic acid residues were represented in the spectra. The lowest charge-state ions were difficult to dissociate with high efficiency and yielded spectra with poorly defined product ion signals. This observation is attributed to sequential fragmentations arising from losses of small molecules such as water and/or ammonia. The poor fragmentation efficiency observed for the low charge states is due at least in part to the low trapping wells used to store the ions. Higher ion stabilities due to lower Coulombic repulsion and charges being sequestered at highly basic sites may also play an important role. Ion/ion proton-transfer reactions involving protein parent ions allows for the formation of a wide range of parent ion charge states. In addition, the ion/ion proton-transfer reactions involving protein dissociation products simplify interpretation of the product ion spectra.     

Arthrodesis of the shoulder for synovial osteochondromatosis

OBJECTIVES: To identify the reasons for non-compliance with fecal occultblood test in the screening programme for colorectal cancer. DESIGN AND SETTING: The people who had never participated in the screening programme for colorectal cancer served as the subjects of this study. A structured questionnaire which included the reasons for rejection was sent to each of non-compliers. They were requested to choose two major reasons which were described in a best way that why they did not participate in the programme. The frequency of the stated reasons were analysed from the viewpoint of both sex and age effects. MAIN RESULTS:A total of 439 people was identified as non-compliers, and 356 (81.1%) people completed the questionnaire. No significant difference was noted in response to the questionnaire between male and female as well as aged 40-59 and those 60-79. The most commonest reason was felt well (47.8%) in male, fear or shyness of further examination (40.2%) in female, and also felt well (48.5%) in aged 40-59, fear or shyness of further examination (40.1%) in aged 60-79. Significant differences were observed in the frequencies of felt well (p<0.01), fear or shyness of further examination (p<0. 01), busy for work (p<0.01) and fear of cancer (p<0.01) between male and female, and also felt well (p<0.01), fear or shyness of further examination (p<0.01), busy for work (p<0.01) and coexistent disease (p<0.01) between aged 40-59 and those 60-79. CONCLUSIONS: These results suggest that public education about the concept of asymptomatic illness, the benefits of early detection, the safety and painless colonoscopy, and the effective treatment should be emphasised to increase compliance with screening for fecal occult blood.