Reactivity of heat-treated coals in steam

Reactivities of seventeen 40 × 100 mesh (U.S.) coals charred to 1000 °C have been measured at 910 °C in 0.1 MPa of a N₂H₂O mixture containing water vapour at a partial pressure of 2.27 kPa. Char reactivity decreases, in general, with increasing rank of the parent coal. The chars show a 250-fold difference in their reactivities. Results suggest that gasification of chars in air, CO₂ and steam involves essentially the same mechanism and that relative gasification rates are controlled by the same intermediate oxygen-transfer step. Removal of inorganic matter from raw coals prior to their charring or from chars produced from raw coals decreases the reactivities of lower-rank chars, whereas reactivities of higher-rank chars increase. Addition of H₂ to steam has a marked retarding effect on char reactivity in most cases. However, in a few cases H₂ acts as an accelerator for gasification. The effect of particle size, reaction temperature and water-vapour pressure on char reactivity is considered.     

Modulated gluconic acid production from immobilized cells of Aspergillus niger ORS‐4.410 utilizing grape must

BACKGROUND: Gluconic acid (GA) production by immobilized cells of mutant Aspergillus niger ORS‐4.410 on polyurethane sponge (PUS) and calcium‐alginate (Ca‐alginate) was evaluated in repeated batches of solid state surface fermentation (SSF) and submerged fermentation (SmF) conditions, respectively, utilizing rectified grape must as carbon source. RESULTS: The passive immobilization of cells in fermentation medium solid support of having 0.4 cm³ cube size, 4% spore suspension, 0.6 g inoculum of PUS immobilized cells at 32 °C and 2.0 L min^?1 resulted in the maximum GA production (88.16 g L^?1) with a 92.8% yield, while the Ca‐alginate matrix with a 0.5 cm diameter bead size, 2–3% spore suspension, 15 g inoculum at 34 °C and 150 rpm agitation speed revealed 67.19 g L^?1 GA with a 85.2% yield. Repeated use of PUS showed higher levels of GA (110.94 g L^?1) in the third–fourth fermentation cycles with 95–98% yield and 22.50 g L^?1 d^?1 productivity under SSF that was 2.5‐fold higher than the productivity obtained from a typical fermentation cycle, and 54% greater than the productivity obtained with repetitive use of Ca‐alginate immobilized cells of A. niger under SmF. CONCLUSION: Using immobilized cells of A. niger in PUS, the rectified form of grape must can be utilized for GA production as an alternative source of carbohydrate by replacing the conventional fermentation conditions. Copyright © 2008 Society of Chemical Industry     

Study of Electrical Conduction Behavior of the System La1−xNaxCo1−xNbxO3 (x 0.50)

Electrical behavior of a few compositions with x 0.50 in the system La_{1− x} Na _x Co_{1− x} Nb _x O₃ has been studied by complex-plane-impedance analysis in the temperature range 300–525 K. Three depressed semicircular arcs have been observed in the complex impedance plot of the composition with x = 0.50. These arcs represent the contributions of bulk, grain boundaries, and electrode polarization to the total observed resistance. Two semicircular arcs have been observed in the complex-impedance plot of the compositions with x = 0.70 and 0.80. They represent the bulk and the grain boundaries contribution to the total observed resistance. The values of the resistance for the bulk and grain boundaries in each sample indicate the formation of barrier layers in these materials.     

Geometrico-Harmonic Broadcasting Scheme With Continuous Redundancy

The harmonic broadcasting scheme has the best performance for the user latency. It, however, does not always provide the video data in time to the users. To provide the video data reliably, its two main variants - cautious and quasi-harmonic schemes have been proposed. They require more bandwidth than the harmonic scheme. The cautious and quasi-harmonic schemes need 0.50 b and 0.1771 b more bandwidth, respectively, than the harmonic scheme in limiting case. In this paper, a new broadcasting scheme: geometrico-harmonic scheme with continuous redundancy is proposed. This scheme provides the video data in time unlike the harmonic scheme, and its bandwidth requirement can be had as close to that of the harmonic scheme as we please. Moreover, the extra bandwidth required in this scheme can be evaluated at any point of time, that is, it can be estimated for a fractional size of a segment and/or subsegment. The bandwidth is a scarce resource and its requirement for any fractional size of segments (or subsegments) may be helpful while dealing with the variable bandwidth rate-encoded videos. In the proposed scheme, the user latency can be made arbitrarily close to that of the harmonic scheme. In comparison to the cautious and the quasi-harmonic schemes, it has better performance for the user latency as well as the buffer storage. For disk transfer rate, it performs better than the quasi-harmonic scheme and in comparison to the cautious harmonic scheme its performance is same     

Comparison of various safety guidelines for electronic article surveillance devices with pulsed magnetic fields

The paper uses the two methods suggested in both the ICNIRP and proposed IEEE safety guidelines for compliance testing of security systems based on time-varying magnetic fields being introduced for electronic article surveillance (EAS), radiofrequency identification, and other applications. For nonsinusoidal pulses that are often used, the two procedures are to treat the exposure as a multifrequency exposure with various frequency components or to calculate the peak induced current densities or electric fields treating the highest of the pulses of duration t(p) as a single frequency, half sinusoid of the same duration and frequency 1/(2t(p)). Using either of the procedures, the induced current densities (J) or electric fields (E) are compared to the basic restrictions on J or E for compliance testing. Using a heterogeneous, tissue-classified anatomic model of the human body, we calculate the induced J and E for the various tissues for a realistic, EAS system for two typical nonsinusoidal pulses to show that the two methods give substantially different results. While the approximate but simpler method of treating the pulse as a half sinusoid results in peak induced J or E that may be compliant with safety guidelines, the rigorous method of treating such exposures as multifrequency exposures gives induced current densities or electric fields that may be up to twice as large, thus making such systems potentially noncompliant with the safety guidelines. Since it is more accurate, it is suggested that safety assessment based on the Fourier analysis leading to multifrequency components be used for compliance testing of such devices.     

Characterisation of bubble materials

The rapid development of magnetic bubble technology has required growth to exacting specifications of a large number of magnetic films of garnets and some amorphous binary and ternary alloys of rare-earth and transition metals. The characterisation of these films is an essential part in the search for newer materials which hold out promise for better device performance and cost viability. Many methods of films characterisation have been reported from time to time. By and large, these methods can be divided into two groups: one, bulk measurements made on the film and two, measurements made on the domains. We have attempted to collate and briefly introduce various techniques to characterise magnetic bubble materials in this review.     

Organic photoconductors: Dark and photoconduction studies in two p-dimethylamino styryl dyes derived from pyridine-2 and pyridine-4

Results of our experiments on the dark and photoconduction studies in two p-dimethylamino styryl dyes derived from pyridine-2 (PDMS-P2) and pyridine-4 (PDMS-P4) in their pure form without any dopant or additive are reported. Measurements on surface-type (raster pattern) cells show that the dark and photocurrents are dependent on the applied potential, temperature, and the photocurrent on the intensity of the incident radiation and the wavelength. Action spectra of the samples could not be recorded as the intensity of the monochromatic radiation from the monochromator reaching the sample was too low to induce any noticeable photocurrent. The compounds show a low dark conductivity. The dark and photocurrents show a perfect ohmic behaviour in the temperature range studied (288–328 K). Since photoconduction could only be observed in a vacuum, this clearly indicates that the compounds are n-type semiconductors. The observed rise and decay kinetics of the photocurrents indicate the presence of traps in the forbidden zone. The dyes show an enhanced photoconduction on illumination with visible radiation only. The marked open circuit voltage and the short-circuit current observed in these compounds indicate a possible application in solar photovoltaics.     

Dielectric relaxator behaviour of the system Sr1−xLaxTi1−xCoxO3 (x ⩽ 0.40)

The dielectric behaviour of the valence-compensated solid solution Sr_1–x La _x Ti_1–x Co_xO₃ (x=0.05, 0.10, 0.20, 0.30 and 0.40) has been studied as a function of temperature and frequency. Compositions withx=0.20, 0.30 and 0.40 exhibit high values of dielectric constant. This high dielectric constant is due partly to the presence of interfacial polarization, and partly to the formation of grain-boundary barrier layers in these materials. The presence of barrier layers is shown by complex plane impedance analysis.     

非易失性可无限次配置的PLD

一、ispXPGA和ispXPLD产品系列iSPXPGA FPGA(Field Programmable Gate Array 现场可编程门阵列)和ispXPLD PLD(Programmable Logic Device 可编程逻辑器件)产品的种类丰富，并以其强大的功能性获得了广泛的应用。该类产品基于SRAM(Static Random Access Memory 静态随机读写存储器)系列产品，允许被重新配置无     

Magnetic and catalytic properties of sintered nickel catalysts for the methanation reaction

Ni catalysts supported on Al₂O₃, as received commercially and subjected to sintering at 723–973 K, were characterised in terms of distinct magnetic structures. It was found that the Ni on all the catalysts consisted of a mixture of single domain structures, with and without anisotropic effects, and multidomain (ferromagnetic) structures. The formation of the multidomain particles during the sintering process coincides with a decrease in catalytic activity for the reaction CO+3H₂°CH₄+H₂O. From this study it was concluded that the methanation reaction is ‘magnetic-structure’ sensitive.