[en] Objective: To clone genes involved in neoplastic transformation induced by α-particles. Methods: Differential display technique was used to identify differentially expressed RNA species between primary and neoplastic transformed rat tracheal epithelial (RTE) cells. Results: Fifteen differentially displayed gene fragments were cloned and sequenced. Among them seven novel gene sequences were submitted to GenBank. Homology searching revealed that Clone ZG 35 was highly homologous to rat Annexin I gene which has been thought to be involved in mitogenic signal transduction as a substrate of EGF receptor kinase, Clone ZC 52 was nearly identical to a novel rattus norvegicus gene for carboxylesterase precursor, and Clone ZC 66 was highly homologous to rat NDPK gene or metastasis suppressor gene nm 23. Sequence analysis suggested that nm 23 may be mutated in the transformed RTE cells and Clone ZA73 was a novel gene fragment. Screening a rat cDNA library using the novel gene Clone ZG52 (Accession number: AF007838) as probe permitted the cloning of a 3.36-kb gene. Sequence analyse and homology searching indicated that the gene contained a unique 1409-bp 5' sequence and a 3' sequence showing high homology toward SRPK2, suggesting that it might be a novel SRPK2-related gene involved in pre-mRNA splicing. Northern hybridization confirmed that the above gene or gene fragments were up-regulated in the transformed RTE cells. Conclusion: These results provide clues to elucidate the mechanisms of radiation onco-genesis and suggest that Annexin I, nm 23, and carboxylesterase precursor gene might be involved in the neoplastic transformation induced by α-particle radiation

[en] Serum-free cultures of primary rat tracheal epithelial (RTE) cells from specific pathogen-free Wistar rats were used to study the cytotoxic potency and transforming effects induced by irradiation with ²³⁸Pu α-particles. The results showed that α-particles were substantially more effective than γ-rays. In terms of D₃₇, the RBE of α-particles was 2.54. For transformation study, primary cell cultures received single exposure to 4 Gy α-particles at a dose rate of 1.26 Gy·min^-1. By successive passaging, passage 40 cells produced invasive squamous cell carcinomas in two out of three animals with a latent period of 4 months upon inoculation into nude mice. This culture system is a useful model to study the mechanism of radiation carcinogenesis

[en] Objective: To determine whether the p53 gene has mutations in transformed RTE cells induced by α-particle irradiation. Methods: Four pairs of oligonucleotide primers corresponding to exon 5-8 of rat p53 gene were synthesized. The PCR-single strand conformation polymorphism (SSCP) analysis was used to prescreen the p53 gene mutations. Results: The single strand of exon 8 had mobility shift in polyacrylamide nondenaturing gel in transformed RTE cells in contrast to normal cells. DNA sequencing proved the mutation to be G→C transverse at codon 265. Conclusions: The mutation of p53 gene was found in transformed RTE cells, suggesting that the change of p53 gene might play an important role in radiation carcinogenesis

[en] Highlights: • Ag@SiO_2 nanoparticles of different silica shell thicknesses were prepared via the Stöber process. • Sm and Dy complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. • The complex-doped Ag@SiO_2 composites show stronger luminescent intensities than pure complexes. • The luminescent intensities of the composites strongly depend on the SiO_2 shell thickness. - Abstract: Three kinds of almost spherical core–shell Ag@SiO_2 nanoparticles of different silica shell thicknesses (10, 25 and 80 nm) were prepared via the Stöber process. The Ag core nanoparticles were prepared by reducing silver nitrate with sodium citrate. The size, morphology and structure of core–shell Ag@SiO_2 nanoparticles were characterized by transmission electron microscopy. Subsequently, eight kinds of lanthanide complexes with benzoate, 1,10-phenanthroline and 2,2′-bipyridine were synthesized. The composition of the lanthanide complexes was characterized by elemental analysis, IR and UV spectra. Finally, lanthanide complexes were attached to the surface of Ag@SiO_2 nanoparticles to form lanthanide-complex-doped Ag@SiO_2 nanocomposites. The results show that the complex-doped Ag@SiO_2 nanocomposites display much stronger luminescence intensities than the lanthanide complexes. Furthermore, the luminescence intensities of the lanthanide-complex-doped Ag@SiO_2 nanocomposites with SiO_2 shell thickness of 25 nm are stronger than those of the nanocomposites with SiO_2 shell thickness of 10 and 80 nm

[en] Objective: To compare the size of target volume, amplitudes of movements in different directions, movement vector, dose to the diseased lung, whole lung volume, and setup error between free breathing fixation (method A) and four-dimensional computed tomography (4DCT)-guided abdominal balloon compression fixation (method B), and to demonstrate that the 4DCT-guided abdominal balloon compression fixation is effective in the treatment of non-small cell lung cancer (NSCLC). Methods: A retrospective analysis was performed among 80 patients with NSCLC in our hospital. In those patients, 40 received method A and 40 method B. The GTV_free and GTV_press were delineated on the maximum intensity projection (MIP) images of 10 respiratory phases using method A and method B, respectively. The GTV_free and GTV_press were obtained by expansion of the GTV_free and GTV_press, respectively. The paired t test was used to analyze the differences in the PTV, maximum amplitudes of movements in three dimensions, absolute value of the movement vector (|V|), and volume between method A and method B. The treatment planning system was used to compare the V₅, V₁₀, V₂₀, and V₃₀ of the diseased lung and the whole lung volume between method A and method B. All patients underwent cone-beam CT (CBCT) scans after positioning. Setup error was obtained by matching the CBCT images with the MIP images in the XVI system based on bone and grayscale values. Results: The GTV_free and GTV_press were (283.2 ± 12.74) and (201.8 ± 12.99)cm³, respectively (P = 0.002). The maximum amplitudes of movements in the right-left, superior-inferior, and anterior-posterior directions as well as the |V| value were (0.22 ± 0.02), (1.85 ± 0.08), (0.43 ± 0.26), and (1.91 ± 0.27) cm, respectively, for method A, and (0.05 ± 0.01), (0.41 ± 0.03), (0.16 ± 0.16), and (0.44 ± 0.16) cm, respectively, for method B (P = 0.120, 0.001, 0.070). The V₅, V₁₀, V₂₀, and V₃₀ for the diseased lung and total lung volume were (61.26 ± 4.27)%, (44.52 ± 1.70)%, (28.22 ± 3.13)%, (18.26 ± 5.17)%, and (3556 ± 223.12) cm³, respectively, for method A, and (52.74 ± 4.78)%, (38.76 ± 4.92)%, (23.71 ± 4.03)%, (15.54 ± 3.43)%, and (3376 ± 311.65) cm³, respectively, for method B (P = 0.001, 0.003, 0.004, 0.021, 0.004). There was no significant difference in setup error obtained by the XVI system between the two fixation methods (P > 0.05). Conclusions: Without increasing setup error, abdominal balloon compression can effectively control the lung movement amplitude, reduce the planning target volume, and reduce the radiation dose to the lung in patients with NSCLC. (authors)

[en] Highlights: • Transient performance of a superheater during switching the load was presented. • Exergy efficiency considering exergy stored variation was applied on a superheater. • Thermodynamic optimization was done by optimizing the superheater parameters. • Exergy efficiency can improve by 1.04 points via regulating the fluid flowrates. • Exergy efficiency can improve by 1.16 points via regulating the fluid temperatures. The boiler superheater undergoes load cycling transients, once the thermal power plant participates in peak shaving. Thermodynamic optimization of a superheater is carried out by optimizing the flowrate/temperature matches between the hot and cold fluids during switching the load rate from 0.75 to 1.00. On the basis of a dynamic model of the superheater, the transient thermal performance is presented. Furthermore, the exergy delivery efficiency of the superheater was analyzed. The superheater outlet temperatures of hot fluid, metal wall, and cold fluid are highly affected when regulating work fluid inlet flowrates/temperatures. During switching the load transient, when increasing the hot fluid flowrate amplitude and variation rate by 50%, the average exergy efficiency (η_E,avg) of the superheater can improve by 1.04% and 0.13%, respectively. When increasing the cold fluid inlet temperature by 5%, η_E,avg can improve by 1.16%. When increasing the hot fluid inlet temperature by 5%, η_E,avg decreases by 0.74%. The exergy efficiency of the superheater is more sensitive to regulating temperature match than the flowrate match during switching the load transient process.

[en] Highlights: • Dynamic models of a 660 MW supercritical coal-fired power plant are developed. • Five measures of regulating extraction steam of high-pressure heaters are analyzed. • Dynamic responses of main thermodynamic parameters and output power are described. • The best strategy of operational flexibility on coal-fired power plant is achieved. The operational flexibility of a thermal power plant has played an essential and promising role in accommodating the increment of variability in the supply and demand sides in China. The rapid activation of thermal storage in entire coal-fired power plant lies at the heart for the strategy. Understanding the thermodynamic characteristics of the power unit in the transient process quantitatively remains a challenge. In this study, dynamic simulations of an entire 660 MW supercritical coal-fired power plant were conducted via GSE software, and the models were validated in the steady state and transient processes. Then, five different measures were introduced to regulate the extraction steam of high-pressure heaters for operational flexibility. The dynamic characteristics of the main thermodynamic parameters and output power were described and compared. Moreover, the operational flexibility of these measures was discussed. It turns out that: among the five measures, the change degrees of pressure, flowrate, and temperature in main devices increase with the increment in the number of throttled valves and/or the degree of feedwater bypass. The feedwater temperature at steady state reduces by 94.6 °C at most, and the maximum temperature change rate of metal slabs in HP heaters is −44.6 °C min⁻¹. The dynamic process for output power under different measures has two different ramp stages, namely, a rapid stage and a slow stage. Furthermore, compared with other measures, 100% throttling extraction steam of #1, #2, and #3 HP heaters has the best operational flexibility, that is, the maximum average power ramp rate in a minute, power capacity, and energy capacity are 6.19% of rate power per minute, 48.40 MW, 5.58 MW h, respectively. The average power ramp rate, power capacity and energy capacity increase with the increment in the number of throttled valves and/or the degree of feedwater bypass. This work is expected to provide a detailed reference on the use of turbine thermal storage to improve the operational flexibility of coal-fired power plants.

[en] Highlights: • Effect of carbon, ash, and moisture in coal on power plant efficiency is evaluated. • Coal-fired unit dynamic characteristics with coal quality variation are obtained. • Dynamic energy consumption with coal quality variation are calculated. • Water-fuel-ratio control strategy considering coal quality variation is proposed. The variation in feeding coal quality is a major issue during coal-fired power unit operation because it causes output power fluctuation, increase in heat losses, and operation safety risks. Given this situation, the effect of coal quality variation on power plant performance should be explored to improve the control strategy considering coal quality variation. In this study, dynamic models of coal-fired power plants are developed. Results show that the unit efficiency decreases when the coal quality worsens, and the carbon, ash, and moisture contents in coal are dominant factors. Dynamic processes with coal quality variation are simulated, and overtemperature risks, deviation of output power, and additional energy consumption are evaluated. Then, the modification of control strategy is proposed to enhance the coal-fired power unit performance, which adds coal quality variation into the water–fuel ratio calculation. With the modified control logic, the duration of the dynamic process is reduced by approximately 40%, and the fluctuation amplitudes of the live and reheat steam temperatures are decreased by approximately 90% and 60%, respectively. In addition, the additional energy consumption is diminished.

[en] Highlights: • Real-time entropy generation rate of the heater is studied during the transients. • Effects of the variation rate and range for the controlled parameters are explored. • Step and ramp variation formats are selected to exhibit the dynamic behaviors. • Influences of the operational parameters on the exergy efficiency are studied. Diminishing fossil fuel resources have intensified the need for energy saving. Heat transfer is a basic method of energy delivery and convention, and heat transfer during the transient processes may be affected by the dynamic performances of heaters. Analysis of the heater performances during the transient process based on the second law of thermodynamics may show the room for the improvement in energy saving. Variations of boundaries, such as the flow rates and temperatures of the work fluids, may affect the dynamic behaviors of heaters. The variation rates, formats and ranges of the inlet work fluids flow rates and temperatures on the irreversibility and exergy delivery characteristics are discussed in this paper. The average exergy efficiency (η_E,avg) of the heater during the transient process with different operational parameters are presented and compared. The results show that, in the identical variation range, the maximum difference in η_E,avg with different flow rates and temperature variation rates of the cold work fluid are 0.3% and 0.4%, respectively. With step variation format, the maximum difference in η_E,avg for the different variation ranges of the cold work fluid is 0.85%.

[en] Highlights: • A novel integrated Lignite-Pyrolysis Poly-Generation System is proposed. • The cascade utilization of energy during drying and pyrolysis process is realized. • 52.55% of overall system efficiency and 4.45% relatively increase are achieved. • The energy saving mechanism of the proposed system is uncovered. The efficient and clean use of lignite is strategically important to sustainable development. Predrying technology is a competitive approach to solve the utilization issue of the high moisture, and the pyrolysis technology is an ideal upgrading method to realize high value-added components extraction. However, the two technologies are normally used separately. By integrating the two technologies, the cascade utilization of energy may be realized, and the utilization efficiency of lignite may be increased accordingly. Therefore, a steam predrying coupled with lignite-pyrolysis power system (PPPS) is proposed in this paper. Theoretical models are developed on the basis of thermodynamics to assess the properties of the proposed system, and a case analysis is performed to determine the quantitative consequences of the PPPS. Moreover, energy and exergy analyses are performed to uncover the energy saving mechanism. Results indicate that the proposed system can evidently increase the thermal efficiency by approximately 4.43% relatively based on the higher heating value, and by approximately 4.45% relatively based on the lower heating value. The PPPS can noticeably increase the exergy efficiency by approximately 4.48% relatively owing to the integration of the lignite predrying and pyrolysis technologies.