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Objective To investigate the effect of vitamin A (VA) deficiency on lung injury in meconium aspiration syndrome (MAS) in newborn rats. Methods After pregnant rats were fed with normal and deficient VA diet, 25 VA-deficient (VAD) and 25 VA-normal (VAN) neonatal SD rats (7 days old) were obtained, respectively. These rats were used to establish MAS mode. The results of blood gas analysis and wet/dry mass ratio of lung tissue were recorded, compared and analyzed in each group. HE staining was employed to evaluate lung tissue injury. The contents of SP-A protein, SP-C protein, IL-6, vascular endothelial growth factor (VEGF) and tumor necrosis factor-α (TNF-α) in lung tissue were detected by ELISA. β-alanine and other metabolites in the lung tissue was measured with high performance liquid chromatography (HPLC). Results The pH value (P=0.003) and base excess (BE) (P=0.019) were significantly lower in the newborn rats from the VAD group than the VAN group. The VAD group had obviously higher partial pressure of carbon dioxide (PCO2) (P=0.049), wet/dry mass ratio of lung tissue (P=0.001), and contents of IL-6 (P=0.002), VEGF (P=0.003) and TNF-α (P=0.019) than the VAD group, suggesting more serious lung inflammation in the VAD group. Further metabolomic analysis showed that the major signaling pathways between VAD and VAN groups included β-alanine metabolism, cGMP-PKG signaling pathway, olfactory transduction pathway, and neural active ligand-receptor interaction pathway. The result of HPLC indicated that β-alanine was notably up-regulated in rats from the VAD group than the VAN group (P=0.000). Conclusion VAD can aggravate lung injury by up-regulating MAS inflammatory factors, which may be related to the changes in β-alanine metabolic pathways caused by VAD.

Objective To investigate the demands of clinical teaching and perception of the theoretical knowledge and clinical practice among nursing undergraduates at school, and provide reference for establishment of a systematic teaching management system and improve the quality of clinical teaching. Methods Totally 161nursing undergraduates at school were recruited by a convenience sampling method, and an open-ended questionnaire survey was conducted to investigate the nursing undergraduates’ demands of clinical teaching. Results The top-ranked demand for clinical teaching was the combination of theoretic knowledge and clinical practice (91. 93%), followed by the diversified teaching methods including video-assisted and real case teaching (85. 71%) and developing students' interest in clinical work(81. 99%). Most of students were satisfied with clinical teaching. Conclusion Clinical teachers should help students build clinical thinking ability by adopting the teaching method combining theory with practice. Clinical teachers should help students build conference and establish identity and self-worth in clinical practice. (目的 调查在校本科护理学生对临床带教老师的需求, 通过了解学生的理论知识与临床实践认知, 为建立系统、完善的教学管理体系, 不断探索完善临床护理实践与理论知识的紧密结合, 从而为提高临床护理教学质量提供参考。方法 采用便利抽样法对某高校161例在校本科护理学生进行临床教学需求问卷调查。结果 在校生护生对“应将书本理论与临床实操练习相结合”的需求最高(91. 93%), 其次为“教学多样化, 如视频、真实案例等教学”(85. 71%)和“教学过程中应培养学生对临床工作的兴趣”(81. 99%)。满意度调查显示, 156(96. 89%)例在校护生对教学满意。结论 在进行临床教学时, 教师可以通过现场理论与实操教学相结合的方式, 让学生建立自己的临床思维, 老师多分享临床经验, 多鼓励学生, 在潜移默化中帮助学生建立自信心, 帮助护理实习生在临床工作中找到自我价值, 从而提高护理教学质量。)

Effective water chemistry technology can inhibit the radiolysis of primary coolants and material corrosion in pressurized water reactors (PWRs). Research and operational experience suggest that methanol is a potential additive for the coolant transformation of PWRs. However, due to a lack of comprehensive understanding regarding the behavior and mechanism of methanol radiolysis in primary circuit scenarios, supporting methanol-based water chemistry control is challenging. This study initially outlines the importance of methanol radiolysis. It then summarizes global research progress on methanol radiolysis and its aqueous solution. Additionally, it discusses the yield of methanol radiolysis products and free-radical reactions at room temperature, as well as the radiolysis of methanol aqueous solutions under primary circuit conditions and its impact on material corrosion, are then discussed in detail. Finally, the study offers suggestions for future research on the radiolysis of methanol aqueous solutions.

At present, most coal mines in China do not have advanced ventilation systems, and local ventilation fans usually use constant frequency operation “one wind”to discharge gas, resulting in low equipment efficiency and serious waste of resources and energy. In view of the above problems, taking a mine as an example, the relationship between gas volume fraction and air demand in roadway was deeply analyzed, and a graded frequency conversion control strategy was proposed, which divided the fan frequency into four levels. The operating conditions of the system frequency upturn and frequency downturn were formulated by combining the fuzzy control theory. The fan control and gas emission under different gas volume fraction conditions were analyzed by numerical simulation method. The results show that this control strategy can keep the gas volume fraction in the working face within the range of 0.5%-0.8%, without complicated decoupling calculation, improve the stability of the system operation to a certain extent, realize “on-demand ventilation” in a real sense, which significantly improves ventilation efficiency and reduces energy consumption.

Objective To investigate the effect of ursolic acid (UA) combined with HDAC2 inhibitor (SA) on the growth and proliferation of human hepatocarcinoma cell line HepG2 and its potential mechanism. Methods CCK-8, optical microscopy, cell clone formation and flow cytometry were used to evaluate the inhibitory effects of UA and SA on HepG2 cells after UA and SA monotherapy or combination therapy. Western blot was used to analyze the expression of HDAC2, AC-α-tubulin CDK2, CDK1, Bax, Bcl-2, and cleaved-PARP in the HepG2 cells after the treatment. Results UA had a significant inhibitory effect on the growth of HepG2 with a concentration and time-dependent manner (P＜0.01); UA inhibited HepG2 cell cloning, and the inhibitory effect was more significant when combined with SA (P＜0.01). UA combined with SA blocked HepG2 cell cycle at G1 phase (P＜0.01); HDAC2 was highly expressed in human hepatoma SMMC-7721, HepG2, and PLC5 cell lines, and UA combined with SA significantly down-regulated HDAC2, Bcl-2, CDK2 and cyclin E1 protein expression, while up-regulated the expression of AC-α-tubulin, Bax and cleaved-PARP. Conclusions The combined application of UA and SA has a synergistic inhibitory effect on the proliferation of HepG2 cells.

The existing variable frequency control method for local ventilator lacks prediction of gas outburst variable. When a large amount of gas emission abnormally, there is a certain lag in regulation, which is easy to lead to gas accumulation. To solve this problem, a variable frequency control system for local ventilator based on fuzzy theory is designed. Fuzzy control is realized by using gas fuzzy controller and air volume fuzzy controller. The control quantity output by two fuzzy controllers is compared. The frequency conversion situation of ventilator is determined according to the larger value. When the two are equal, the fuzzy control of gas is dominant. The classification method based on gas emission is adopted. With the air volume corresponding to the farthest working point as the auxiliary, the ventilator frequency is divided into 4 levels. The gas volume fraction of the heading working face reaching 0.8% is set as the frequency-increasing condition. The gas volume fraction not more than 0.6% or 0.5% is set as the frequency-reducing condition. Moreover, the air supply quantity of the ventilator after frequency reduction is set as the air supply volume required to control the gas volume fraction of return airflow at 0.7% or 0.6% when the frequency reduction condition is achieved. When a large amount of abnormal gas emission, the ventilator is increased in frequency to reduce the gas concentration. At the same time, the air supply volume of the ventilator can meet the greater gas discharge demand. The ventilator can provide a certain buffer for adjustment, and overcome the shortcomings of frequency conversion control lag. The test results show that the gas volume fraction is 0.5% under the condition of frequency reduction. The air supply volume after frequency reduction is the air supply volume required to control the gas volume fraction of return air at 0.6% when the frequency reduction condition is achieved. The control effect is good under this condition. But the air supply volume of level I is slightly less than the minimum air supply volume required at the farthest heading distance. The new frequency level I* between level I and level II can be set. The air supply volume can be increased by increasing the frequency of the ventilator to meet the minimum air supply volume requirement at the farthest heading distance.

Dipeptidyl peptidase 4 (DPP4) inhibitors(oral hypoglycemic agents)have beneficial effects during the early stages of diabetes. In this study, we evaluated the role of DPP4inhibitorsonthe biological functions of cultured human endothelial progenitor cells (EPCs). After treating EPCs with the DPP4 inhibitors sitagliptin and vildagliptin, we examined the mRNA expression of DPP4, vascular endothelial growth factor (VEGF),VEGF receptor 2 (VEGFR-2),endothelial nitric oxide synthase (eNOS), caspase-3,stromal cell-derived factor-1 (SDF-1), chemokine (C-X-C motif) receptor 4 (CXCR4) were measured by RT-PCR. The protein expression of SDF-1 and CXCR4 was determined by Western blot; cell proliferation was tested by the MTT method, and DPP4 activity was determined by a DPP4 assay. Our results revealed that DPP4 expression and activity were inhibited following the treatment with various doses of DPP4 inhibitors. Cell proliferation and the expression of VEGF, VEGFR-2andeNOS were up regulated, while cell apoptosis was inhibited by DPP4 inhibitors in a dose-dependent manner. DPP4 inhibitors activated the SDF-1/CXCR4 signaling pathway, shown by the elevated expression of SDF-1/CXCR4. This further proved that after the SDF-1/CXCR4 signaling pathway was blocked by its inhibitor ADM3100, the effects of DPP4 inhibitors on the proliferation and apoptosis, and the expression of VEGF, VEGFR-2and eNOS of EPCs were significantly reduced. These findings suggest that DPP4 inhibitors promote the biological functions of human EPCs by up regulating the SDF-1/CXCR4 signaling pathway.

DOI：10.3969/j.issn.1672-6731.2010.02.024

ANSYS can be a powerful tool to simulate the process of energy exchange in magnetically-coupled resonant wireless power transfer system. In this work, the MCR-WPT system with single intermediate coil resonator is simulated and researched based on scattering parameters using ANSYS Electromagnetics. The change rule of power transfer efficiency is reflected intuitively through the scattering parameters. A new method of calculating the coupling coefficient is proposed. A cascaded 2-port network model using scattering parameters is adopted to research the efficiency of transmission. By changing the relative position and the number of turns of the intermediate coil, we find some factors affecting the efficiency of transmission. Methods and principles of designing the MCR-WPT system with single intermediate coil resonator are obtained. And these methods have practical value with design and optimization of system efficiency.

TiO2 thin films doped with neodymium(Nd) in the range from 0 at.% to 10at. % were prepared on glass substrates by sol-gel dip-coating method. Water contact angle on the Nd-doped TiO2 films were measured by contact angle analyzer. The water contact angle measurement result showed that the hydrophily of the films improved when the Nd3+ concentration increased to 5 at.%. The photocatalytic activity of the undoped and Nd-doped TiO2 thin films were investigated by the degradation of methylene blue under high-voltage mercury lamp. The results showed that 5 at.% Nd-doped TiO2 thin film exhibited the highest photocatalytic efficiency.