100,488 research outputs found
Gas and solid behaviours during defluidisation of Geldart-A particles
No full textBed collapsing experiments were carried out in a cold-air transparent column 192 mm in diameter and 2 m high. Typical Fluid Catalytic Cracking (FCC) catalyst with a mean particle size of 76 μm and a density of 1400 kg/m3 was used. Both single and double-drainage protocols were tested. The local pressure drop and bed surface collapse height were acquired throughout the bed settling.Typical results were found regarding dense phase voidage of a fluidised bed and the bed surface collapse velocity. In addition, bubble fraction was calculated based on the collapse curve.Experimental results showed that windbox effect is significantly reduced compared to previous works since the volume of air within the windbox was reduced. The comparison of single/double-drainage protocols revealed a new period in the defluidisation of Geldart-A particles concerning gas compressibility. Through the temporal analysis of local pressure drop, the progress of the solid sedimentation front from bottom to top was determined, analysed and modelled
Temperature dependent resistivity in the low resistance region for diffusive transport in two-dimensions
No full textThe interpretation of the metal-insulator transition phenomena in disordered two-dimensional electron systems in terms of density-dependent scaling variables suggests the existence of a quantum critical point at some critical electron density. However a first principles scaling theory based on renormalization group (RG) methods predicts a strong temperature dependence of the dimensionless resistivity R(T), even at small R(T), that is not observed. The observed properties are in fact consistent with a weakly disordered Fermi liquid, and there are no indications of strong temperature dependence induced by scaling. While the RG expansion in a power series in R(T) has only been evaluated to lowest order, this should be sufficient to describe experiments in the region of very small R. A further apparent anomaly is a return from metal-like to insulating-like behavior for increasing density. We explain these fundamental discrepancies between the first principles theory and experiment. We find that the R<<1 data in the currently attainable temperature range are in a weak scaling regime described by the logarithmic approximation. We independently determine the density dependent prefactor of the logarithm using data for the spin susceptibility and effective mass. We find good agreement between theory and experiment for R(T) in the diffusive regime. We point out that there are corrections to the leading logarithm approximation that should be observable at still lower temperatures
An unusual differential diagnosis of penile warts: metastases from rectal carcinoma
No full textPatients with penile lesions, such as virally induced papillomata, frequently present to genitourinary medicine clinics and general practitioners. Their diagnosis is usually based on clinical observation and biopsy is not generally undertaken. Penile lesions may rarely have a more sinister aetiology and represent metastatic spread from solid tumours arising at distant sites. Penile metastases arise most frequently from genitourinary cancers (prostate, bladder and kidney), but may also arise from tumours of the large bowel; other primary sites are extremely uncommon. We report the case of a patient presenting with penile metastases from rectal carcinoma arising during third-line chemotherapy for metastatic diseas
Computational characterisation of intermittent hydrodynamic behaviours in a riser with Geldart A particles
No full textIn the riser of a gas-solid circulating fluidised bed (CFB) with Geldart A particles, the multiscale interactions and diverse coherent structures give rise to an important hydrodynamic phenomenon called flow intermittency. In this work, the two-fluid model incorporating the energy minimisation multi-scale (EMMS) drag model is employed to simulate the gas-solid flow in the riser. The predicted fluctuating signals are processed to acquire the intermittency indices, wavelet flatness factors, power spectra of solids volume fraction fluctuation, probability density function (PDF) of wavelet coefficients for solids fluctuating velocity, and PDF of solids volume fraction, based on which the flow intermittency and effects of coherent structures are characterised. The results presented in this paper reveal that the EMMS-based computational fluid dynamics (CFD) simulation in combination with the fluctuating signal analysis provide an in-depth understanding of the intermittent flow behaviours in the riser with Geldart A particles. Particle clusters and particle vortices are identified as typical coherent structures in the riser, and the flow intermittency, caused by the flow field heterogeneity and the presence of coherent structures, is found to be significantly dependent on the radial locations and operation conditions
Clinical outcomes following neoadjuvant cisplatin-based chemotherapy for bladder cancer in elderly compared with younger patients
No full textBladder cancer is a disease of the elderly. Older patients might potentially be undertreated due to assumptions about benefit versus risk. Our objective was to determine outcomes in older patients receiving neoadjuvant chemotherapy for muscle-invasive bladder cancer (MIBC). We hypothesised that appropriately selected elderly patients (?70 years) with MIBC could have similar clinical outcomes, and be safely treated, with standard neoadjuvant chemotherapy prior to definitive cystectomy or radiotherapy. We utilised a single institution case series analysis of patients with T2-4a N0 M0 transitional cell carcinoma of the bladder treated with cisplatin-based neoadjuvant chemotherapy between 2005 and 2011. Eighty-three patients were eligible. Median age was 68 (range 48–80), 33 patients (40%) were ?70 years. Overall survival at 3 years was 65.8% (?70) and 63.2% (<70) (P = 0.653), relapse-free survival at 3 years was 61.6% and 54.8% respectively (P = 0.471). The rates going forward to definitive local therapy (87.9% ? 70 and 84.0% < 70) and the pathological complete response rate (31.3% ? 70 and 40% < 70) were similar. Disease relapse rate was also similar (63.6% ? 70 vs. 60% < 70, P = 0.906). Elderly patients with good functional status and limited comorbidities diagnosed with MIBC receiving standard neoadjuvant chemotherapy followed by cystectomy or radiotherapy can have similar clinical outcomes as their younger counterparts. Prospective studies evaluating the optimum curative management in this elderly population are warranted
Quantum Critical Behaviour in the Insulating Region of the 2D Metal Insulator Transition
No full textWe show the insulating region of the metal-insulator transition phenomena in disordered two-dimensional electron systems contains new information about the quantum critical dynamics at low T because the insulating region and the quantum critical region are two aspects of the localized phase
Low Temperature Properties of 2D Correlated Electrons in Weakly Disordered Materials
No full textTransport properties of extremely high purity two-dimensional (2D) electron systems at low temperatures are still not well understood either experimentally or theoretically, even though these systems are fast becoming a mainstream basis of computing devices. In fact there are two separate issues to be resolved. The first of these has attracted the more attention. This is the existence of a quantum phase transition (the metal-insulator transition) in the low density 2D system at zero temperature. Experimentally, in spite of claims, from existing data at finite temperatures there is no conclusive evidence either way on the existence of a T = 0 quantum phase transition. There is a need for a unified theory encompassing, on the same level, both insulating and metallic behaviour to predict the cross-over. We propose a semi-empirical one parameter renormalisation group equation for the temperature dependent resistivity of a 2D electron system with weak disorder. The renormalisation group equation has a physically meaningful insulating limit and it predicts a metallic ground state of zero resistance at higher electron densities. The resulting temperature dependence of the resistivity is found to give a good fit to experimental data near the separatrix. The second issue is the mechanism behind the sudden change in the temperature dependence of the resistivity, as is actually observed at low but non-zero temperatures, T = 0.1 to 2 K. This phenomenon is well-documented experimentally and it is of interest in its own right whether or not there is an actual transition at T = 0. We present direct evidence of the important role of the electron Coulomb repulsion and exchange in determining these finite temperature properties by noting an empirical relationship between the critical density at the bifurcation point and parallel magnetic field. The relationship is controlled by properties of the electron-electron correlation function for the 2D electron system. This result provides direct evidence of the central role of the Coulomb repulsion and exchange in driving the bifurcation phenomenon
Quantum critical point description of the 2D metal insulator transition
No full textWe argue that a quantum critical point associated with the putative metal–insulator transition phenomenon in 2D controls not only the usual quantum critical sector but also a range of the low temperature insulator sector. The extended range of criticality permits a unified analysis of data from the insulating critical sector and quantum critical sector. Both the dynamical critical exponent z and the correlation length critical exponent can then be determined from published data from a single experiment in the insulator critical region. The resulting value of is consistent with the T dependence of the resistivity in the quantum critical sector which provides support for the presence of a quantum critical point
The combination of raltitrexed (Tomudex) and mitomycin-C in the treatment of advanced colorectal cancer - A phase II study
No full textAims
To investigate the combination of raltitrexed and mitomycin-C as first-line chemotherapy treatment in patients with advanced colorectal cancer.Materials and methods
A phase II study.Results
In total, 22 patients were treated with a combination of raltitrexed 3 mg/m2 every 3 weeks and mitomycin-C 7 mg/m2 every 6 weeks for up to 24 weeks. The study was closed early for safety reasons as there were three unexpected treatment-related deaths. The overall response rate was 20%, and a further 40% achieved stable disease. The median time to progression was 3.9 months and the median overall survival time was 11.6 months.Conclusion
Owing to the potential for increased toxicity, the combination of raltitrexed and mitomycin-C cannot be recommended as first-line treatment in patients with advanced colorectal cancer
Measurement of Flow Characteristics in a Bubbling Fluidized Bed Using Electrostatic Sensor Arrays
No full textFluidized beds are widely applied in a range of industrial processes. In order to maintain the efficient operation of a fluidized bed, the flow parameters in the bed should be monitored continuously. In this paper, electrostatic sensor arrays are used to measure the flow characteristics in a bubbling fluidized bed. In order to investigate the electrostatic charge distribution and the flow dynamics of solid particles in the dense region, time and frequency domain analysis of the electrostatic signals is conducted. In addition, the correlation velocities and weighted average velocity of Geldart A particles in the dense and transit regions are calculated, and the flow dynamics of Geldart A and D particles in the dense and transit regions are compared. Finally, the influence of liquid antistatic agents on the performance of the electrostatic sensor array is investigated. According to the experimental results, it is proved that the flow characteristics in the dense and transit regions of a bubbling fluidized bed can be measured using electrostatic sensor arrays
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