Chemostat and total cell retention cultures with internal filter system ofSaecharomyc.es cerevisiae H1-7 were carried out to produce ethanol from wood hydrolysate. Maximum ethanol productivity obtained in a chemostat with
the aeration rate of 1 vvm was 3.79 g/(L·h). This was 20% higher than that in a chemostat without aeration. However, the substrate
was not completely consumed at the dilution rate with the maximum productivity. The realistic productivity, which has higher
than 99% conversion rate of substrate, was. 2.95 g/(L·h). The maximum productivity in the total cell retention culture was
6.65 g/(L·h) at the dilution rate of 0.19 h1 and the residual glucose concentration was negligible. 相似文献
A coiled quartz tubular reactor has been designed to measure the intrinsic reaction kinetics for homogeneous reactions at high temperatures up to 1100°C. Actual gas residence times were less than 100 ms. A simple and well‐studied test reaction (i.e., the decomposition of nitrous oxide, N2O), with published intrinsic kinetics, was used to verify the operation of the experimental reactor. For this system, Peclet numbers (Pe = uL/DL) computed from experimental conversion data were greater than 1000, indicating that the plug flow assumption could be used with this reactor system to determine intrinsic rate expressions with errors of less than 5% for the conditions studied. 相似文献
Ce3+/Tb3+ co-doped NaMgBO3 phosphors were successfully synthesized by solid-state method. Under 381 nm excitation, the cyan emission owing to the 5d → 4f of Ce3+ ions and green emissions arising from the 5D4 → 7FJ (J = 6, 5, 4, and 3) transitions of Tb3+ ions were seen in all the phosphors. Through theoretical analysis, one knows that the energy transfer from Ce3+ to Tb3+ ions with high efficiency of 83.74% was contributed by dipole–dipole transition. Furthermore, the internal quantum efficiency of NaMgBO3:0.01Ce3+,0.03Tb3+ phosphor was 54.28%. Compared with that of at 303 K, the emission intensity of the developed products at 423 K still kept 73%, revealing the splendid thermal stability of the studied phosphors. Through utilizing the resultant phosphors as cyan-green components, the fabricated white-LED device exhibited an excellent correlated color temperature of 2785 K, high color-rendering index of 85.73, suitable luminance efficiency of 25.00 lm/W, and appropriate color coordinate of (0.4279, 0.3617). Aside from the superior photoluminescence, the synthesized phosphors also exhibited excellent cathode-luminescence properties which were sensitive to the current and accelerating voltage. Furthermore, the NaMgBO3:0.01Ce3+,0.03Tb3+ phosphors with multi-mode emissions were promising candidates for optical anti-counterfeiting. All the results indicated that the Ce3+/Tb3+ co-doped NaMgBO3 phosphors were potential multi-platforms toward white-LED, field emission displays, and optical anti-counterfeiting applications. 相似文献
Standardization of Fourier transform infrared (FTIR) fingerprint region for paints and assessment on the reproducibility using different spectrophotometers were investigated. While selective fingerprint regions may be confusing for technicians/analysts who are non-chemists, we attempt to generalize these regions (e.g., 1300–1000 cm−1 for Epoxy part A and 1400–1000 cm−1 for Epoxy part B) by choosing a universal region (2000–900 cm−1) that works for different paints. Comparison result using a paired student t-test shows that the degree of similarity (r) values from the studied regions are not statistically different. The paint fails the screening analysis occasionally on-site when analyzed using handheld FTIR due to the higher level of noise that gives low r values (r < 0.900 ± 0.002). The same samples were analyzed using a benchtop FTIR and the r values are above 0.900 ± 0.002. While the screening may lead to a false rejection of the sample on-site, there could be occurrence of false acceptance. The on-site screening of EPZ part A with different formulations, for instance, shows that the r values over the entire IR spectrum are above 0.900 ± 0.002 when analyzed using handheld FTIR. After the samples were analyzed using the benchtop, the r values fall below 0.900 ± 0.002. 相似文献
In a continuous casting steelmaking operation, the surface of a slab is under a condition that can be characterized as high-temperature,
low-cycle fatigue in which the tensile and compressive stress is repeatedly developed. For this reason, for the evaluation
of the hot ductility of a slab, considering the fatigue deformation is more feasible before a tensile or compressive test.
In this study, the effects of low-cycle fatigue on the hot ductility of steels with a carbon content of 0.06–0.8 wt.% are
investigated at various temperatures. For a carbon content of 0.06%, there were no significant differences between the RA
values from a simple tensile test and those from a tensile test after fatigue deformation. The tendency of ductility deterioration
with fatigue deformation is evident in 0.1 %C steel, and is due to the deformation-induced ferrite film that forms around
the prior austenite grain. Conversely, high carbon steel containing 0.8 %C did not show a recovery of hot ductility in a low
temperature region, and the specimen on which the tensile was measured after fatigue showed a higher hot ductility in the
low temperature region, which is thought to result from the pearlite refinement effects. As the results obtained in this work
showed noticeable differences in the hot ductility of carbon steel through the test conditions, it is suggested that for more
accurate data, fatigue deformation be adopted in which the temperature range in an unbending operation is determined in the
steelmaking factory. 相似文献
Research was conducted on tailored blank welding between mild steel sheet and Zn-coated steel sheet using CO2 laser beam. The materials used in this study were low carbon steel sheets with a thickness of 1.2 mm and Zn-coated steel
sheet with the same thickness and 6.3 μm Zn coating. Experiments were conducted by applying the Taguchi method to obtain optimum
conditions for the application of this tailored blank laser welding method in practical manufacturing processes. Optical microscopy,
XRD, SEM and TEM analysis were performed to observe the microstructures and to determine the structures of welded zone. In
addition, mechanical properties were measured by the microhardness test, tensile test and Erichsen test to evaluate the formability
of the welded specimen. There was no trapped Zn in the fusion zone, and the phases of this region consisted of polygonal ferrite,
quasi-polygonal ferrite, banitic ferrite and martensite. The elongation value of welded specimen was more than 80% of the
value in substrate metal, and the LDH value was more than 90% of the value in substrate metal. 相似文献
Inhomogeneous plastic deformation that develops during wire-drawing, and its impact on the drawing force, are investigated with a computational method. The effects of critical parameters, including die angle, area reduction, friction coefficient, and material hardening are sorted out, and the accuracy of certain simple formulas presented in the literature is assessed. The results suggest that the redundant strains (strains beyond those necessary for area reduction) are dependent principally on the die angle and area reduction; the interfacial friction and the strain hardening tend to have little influence on the strains. In addition, the impact of spatial inhomogeneity in hardness induced by strain hardening from prior passes is investigated. 相似文献
In the conventional metallothermic reduction (MR) process used to obtain tantalum powder in batch-type operation, it is difficult
to control the morphology and location of the tantalum deposits. In contrast, an electronically mediated reaction (EMR) process
is capable of overcoming this difficulty. It has the advantage of being a continuous process, but has the disadvantage of
a poor reduction yield. A process known as the MR-EMR combination process is able to overcome the shortcomings of the MR and
EMR processes. In this study, an MR-EMR combination process is applied to the production of tantalum powder via sodium reduction
of K2TaF7. In the MR-EMR combination process, the total charge passed through an external circuit and the average particle size (FSSS)
increase as the reduction temperature increases. In addition, the proportion of fine particles (−325 mesh) decreases as the
reduction temperature increasess. The tantalum yield improved from 65 to 74% as the reduction temperature increased. Taking
into account the charge, impurities, morphology, particle size and yield, a reduction temperature of 1123 K was found to be
optimum for the MR-EMR combination process. 相似文献
The useful life of a cutting tool and its operating conditions largely control the economics of the machining operations. Hence, it is imperative that the condition of the cutting tool, particularly some indication as to when it requires changing, to be monitored. The drilling operation is frequently used as a preliminary step for many operations like boring, reaming and tapping, however, the operation itself is complex and demanding.
Back propagation neural networks were used for detection of drill wear. The neural network consisted of three layers input, hidden and output. Drill size, feed, spindle speed, torque, machining time and thrust force are given as inputs to the ANN and the flank wear was estimated. Drilling experiments with 8 mm drill size were performed by changing the cutting speed and feed at two different levels. The number of neurons in the hidden layer were selected from 1, 2, 3, …, 20. The learning rate was selected as 0.01 and no smoothing factor was used. The estimated values of tool wear were obtained by statistical analysis and by various neural network structures. Comparative analysis has been done between statistical analysis, neural network structures and the actual values of tool wear obtained by experimentation. 相似文献