The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery semi-coke. The characteristic of low ...volatile results in poor combustion performance and high NO
x
emission, and to co-fire with bituminous coal is a practical strategy to address this problem. However, the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently understood. In addition, the influences of secondary air arrangement, the boiler operation load, and the fuel type on co-combustion process are still unclear, which is urgent to be further explored. In the present study, experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NO
x
emission features of semi-coke and coal. The results demonstrated that the “out-furnace method” was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%, due to the limited combinations of the semi-coke injection position. It was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the “in-furnace method” to improve the overall co-combustion performance. The critical value of the separated over fire air ratio in this study was 27.5%, over which a slight drop of carbon content in fly ash could come about. Moreover, the elevation in the proportion of separated over fire air gave rise to the significant decline of NO
x
concentration. The constricted secondary air arrangement was preferred to be employed due to the high boiler efficiency. The separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NO
x
emissions and the coking of nozzles. For the load reduction regulation method adopted in this study, the NO
x
concentration first rose and then dropped, while the burnout ratio decreased obviously as the operation load was reduced. Different combinations of coal and semi-coke generated significant influences on co-combustion behaviors within the furnace. The NO
x
generated by high-volatile fuel (bituminous coal) combustion was mainly affected by volatile-N, while the NO
x
generated by low-volatile fuel (semi-coke) was mainly impacted by char-N. This study is of guiding significance for the efficient and clean utilization and beneficial to the large-scale application of powder semi-coke in power plants.
In the present work, we study theoretically the electron wave's focusing phenomenon in a single-layered graphene pn junction (PNJ) and obtain the electric current density distribution of graphene ...PNJ, which is in good agreement with the qualitative result in previous numerical calculations (Cheianov et al 2007 Science, 315, 1252). In addition, we find that, for a symmetric PNJ, 1/4 of total electric current radiated from the source electrode can be collected by the drain electrode. Furthermore, this ratio reduces to 3/16 in a symmetric graphene npn junction. Our results obtained by the present analytical method provide a general design rule for an electric lens based on negative refractory index systems.
Spontaneous polygonization for a multi-walled carbon nanotubes (MWCNTs) have been observed for about two decades. In present manuscript, this phenomenon is understood by the competition between ...cohesion energy (with lattice mismatching effect) and curvature elastic energy of tubes inside the MWCNTs. Based on a continuum elastic model and perturbation analysis, the crucial conditions for spontaneous polygonization of MWCNT is expressed by fundamental parameters of MWCNTs, which are in reasonable agreement with all relevant experiments and computer simulations reported in literatures. Present approach can be used in further studies of crossectional geometry-dependent properties of MWCNTs.
The stochastic systems without detailed balance are common in various chemical reaction systems, such as metabolic network systems. In studies of these systems, the concept of potential landscape is ...useful. However, what are the sufficient and necessary conditions of the existence of the potential function is still an open problem. Use Hodge decomposition theorem in differential form theory, we focus on the general chemical Langevin equations, which reflect complex chemical reaction systems. We analysis the conditions for the existence of potential landscape of the systems. By mapping the stochastic differential equations to a Hamiltonian mechanical system, we obtain the Fokker-Planck equation of the chemical reaction systems. The obtained Fokker-Planck equation can be used in further studies of other steady properties of complex chemical reaction systems, such as their steady state entropies.
In present work, we theoretically study the electron wave's focusing phenomenon in a single layered graphene pn junction(PNJ) and obtain the electric current density distribution of graphene PNJ, ...which is in good agreement with the qualitative result in previous numerical calculations Science, 315, 1252 (2007). In addition, we find that for symmetric PNJ, 1/4 of total electric current radiated from source electrode can be collected by drain electrode. Furthermore, this ratio reduces to 3/16 in a symmetric graphene npn junction. Our results obtained by present analytical method provide a general design rule for electric lens based on negative refractory index systems.
Previous studies show that transient axonal glycoprotein-1, a ligand of amyloid precursor pro- tein, increases the secretion of amyloid precursor protein intracellular domain and is involved in ...apoptosis in Alzheimer＇s disease. In this study, we examined the effects of transient axonal glyco- protein-1 on U251 glioma cells. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that transient axonal glycoprotein-1 did not inhibit the proliferation of U251 cells, but promoted cell viability. The terminal deoxynucleotidyl transferase dUTP nick end labeling assay showed that transient axonal glycoprotein-1 did not induce U251 cell apoptosis. Real-time PCR revealed that transient axonal glycoprotein-1 substantially upregulated levels of amyloid precursor protein intracellular C-terminal domain, and p53 and epidermal growth factor recep- tor mRNA expression. Thus, transient axonal glycoprotein-1 increased apoptosis-related gene expression in U251 cells without inducing apoptosis. Instead, transient axonal glycoprotein-1 promoted the proliferation of these glioma cells.
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