电磁永磁混合EMS型磁浮列车的吸死防护问题研究

研究电磁永磁混合EMS型磁浮列车的吸死防护问题。从理论角度要求风险存在时防护措施既能有效防止吸死,又不会因误保护动作而影响列车正常运行。由此提出一种充分利用间隙变化信息的判定依据,并设计降维观测器及一套独立于悬浮控制器的吸死防护系统。系统由预测模块和保护模块构成。仿真结果表明该吸死判定依据预测准确,防护及时有效。实验结果表明该防护系统能够结合悬浮控制系统,较好地完成悬浮和吸死防护任务。

永磁电磁混合磁悬浮列车吸死防护技术研究

相对传统的电磁型磁悬浮(EMS)列车,永磁电磁混合型磁悬浮(PEMS)列车可以降低功耗、减少发热,还可以实现大气隙悬浮,但存在吸死的可能是目前阻碍其向工程应用发展的最大障碍,提出一种新型永磁电磁混合磁铁结构,使得系统具备冗余性,并通过理论和仿真分析新结构的合理性和有效性,能很好地完成悬浮和吸死防护任务,分析了相应的控制器改造的可行性。

基于不等宽结构的混合型悬浮装置的研究

针对中低速磁悬浮列车中永磁与电磁混合悬浮磁铁存在的吸死问题,研究了一种基于不等宽结构的混合悬浮装置。分析该装置中U型铁、F型轨及两者间气隙的电磁关系,建立基于不等宽结构悬浮装置的模型。以株洲中低速磁浮商业试验线列车为基础,使用ANSOFT软件进行仿真,对该悬浮装置进行了设计及验证。仿真结果表明:在改进的不等宽混合悬浮装置中,无论气隙间距大小如何,该不等宽结构中的悬浮力始终与重力保持平衡,可实现列车悬浮的"0功率"控制。

磁浮列车永磁电磁混合悬浮导向系统特性分析

针对中速磁浮列车悬浮系统节能降耗的需求,提出了一种永磁电磁混合悬浮导向系统。根据永磁电磁混合悬浮导向系统的工作原理,确定了其结构组成,完成了悬浮力特性、自导向特性分析,以及气隙控制方式和防吸死控制策略研究;在建立系统数学模型和仿真模型的基础上,对系统方案进行仿真验证,并对混合悬浮电磁铁的悬浮损耗、温升、悬浮控制器性能、悬浮系统在平直道和曲线段的悬浮导向能力和承载力等进行测试。试验结果表明,永磁电磁混合悬浮导向系统具有承载能力强、悬浮电流小,发热量少等优点,系统的自适应能力满足中速磁浮列车运行的要求,可为中速磁浮列车的推广应用奠定基础。

Ulcerative colitis in smokers,non-smokers and ex-smokers

Smoking is a major environmental factor that interferes in the establishment and clinical course of ulcerative colitis (UC). Firstly, the risk of smoking status impact in the development of UC is reviewed, showing that current smoking has a protective association with UC. Similarly, being a former smoker is associated with an increased risk of UC. The concept that smoking could have a role in determining the inflammatory bowel disease phenotype is also discussed. Gender may also be considered, as current smoking delays disease onset in men but not in women. No clear conclusions can be driven from the studies trying to clarify whether childhood passive smoking or prenatal smoke exposure have an influence on the development of UC, mainly due to methodology flaws. The influence of smoking on disease course is the second aspect analysed. Some studies show a disease course more benign in smokers that in non-smokers, with lower hospitalizations rates, less flare-ups, lower use of oral steroids and even less risk of proximal extension. This is not verified by some other studies. Similarly, the rate of colectomy does not seem to be determined by the smoking status of the patient. The third issue reviewed is the use of nicotine as a therapeutic agent. The place of nicotine in the treatment of UC is unclear, although it could be useful in selected cases, particularly in recent ex-smokers with moderate but refractory attacks of UC. Finally, the effect of smoking cessation in UC patients is summarised. Given that smoking represents a major worldwide cause of death, for inpatients with UC the risks of smoking far outweigh any possible benefit. Thus, physicians should advise, encourage and assist UC patients who smoke to quit.

卷烟机翼板改造

针对卷烟机翼板存在的缺陷,参照国外先进机组的经验及机械设计原理,把故障源吸丝带轮与翼板分开,改变吸丝带的支撑方式,增加负压调节,有效地解决翼板缺陷,提高设备有效作业率。

Additional manual thrombus aspiration for ST-segment elevation myocardial infarction during percutaneous coronary intervention： an updated meta- analysis

Background The clinical efficacy and safety of adjunctive thrombus aspiration （TA） in patients with ST-segment elevation myocardial infarction （STEMI） during percutaneous coronary intervention （PCI） remain controversial. Methods Twenty five eligible randomized controlled trials were included to compare the use of thrombus aspiration （TA） with PCI and PCI-only for STEMI. The primary endpoint was all-cause mortality and death. The secondary endpoints were major adverse cardiac events （MACE）, recurrent infarction （RI）, target vessel revascularization （TVR）, stent thrombosis （ST）, perfusion surrogate markers and stroke. Results TIMI flow grade 3 and MBG 2-3 were significantly increased in the TA plus PCI arm compared with the PCI-only arm [relative risk （RR）： 1.05, 95% confidence intervals （CI）： 1.02-1.09, P = 0.004] and （RR： 1.68, 95% CI： 1.40-2.00, P 〈 0.001）, respectively. There were no significant differences in all-cause mortal- ity, MACEs, TVR and ST rates between the two groups. The RI rate was lower in the TA plus PCI arm than that in the PCI-only arm with short-term follow-up duration （RR： 0.60, 95% CI： 0.38-0.96, P = 0.03）, but there was no significant difference in RI incidence over the me- diumor long-term follow-up periods （RR： 1.00, 95% CI： 0.77-1.29, P = 0.98）, and （RR： 0.96, 95% CI： 0.81-1.15, P = 0.69）, respectively. There were statistically significant differences in the rates of crude stroke and stroke over the medium- or long-term follow-up periods and the crude stroke rate in the TA plus PCI （RR： 1.60, 95% CI： 1.08-2.38, P = 0.02） and （RR： 1.43, 95% CI： 1.03-1.98, P = 0.03）, respectively; this was not observed between the two arms during the short-term follow-up period （RR： 1.47, 95% CI： 0.97-2.21, P = 0.07）. Conclusions Routine TA-assisted PCI in STEMI patients can improve myocardial reperfusion and get limited benefits related to the clinical endpoints, which may be associated with stroke risk.

冒死吸“毒”

一家造纸厂需要清理一个污水池，有两位工人下到了池里，他们的班长在池上检修一根水管。10分钟后，班长感觉不对劲，因为之前他一直听到两位工友在下面对话，而现在没有动静了。班长放下手中的工具，走到池边往下一看，他惊呼起来：“有人中毒了！快来人哪！”

Impacts of Climate Change on Human Health and Adaptation Strategies in South China

This study reviews the impacts of climate change on human health and presents corresponding adaptation strategies in South China. The daily mean surface air temperatures above or below 26.4~C increase the death risk for people in Guangzhou, especially the elderly are vulnerable to variations in temperature. Heat waves can cause insomnia, fatigue, clinical exacerbation, or death from heatstroke etc., while cold spells show increases in patients with fractures. During a cold spell period, the rates of both on-site emergency rescues and non-implementable rescues increase, and the risk of non-accidental deaths and respiratory disease deaths significantly rise as well. Both time series of hazy days and ozone concentrations have significant positive correlations with the number of patients with cardiovascular diseases. Both malaria and dengue fever reach higher altitudes and mountainous areas due to climate warming. Climate change is likely to bring stronger heat waves in the future, thereby increasing heat wave-related illnesses and deaths, particularly in the metropolitan areas of the Pearl River Delta. The projected increase of consecutive cold days in Guangdong province and parts of northern Guangxi province will affect residents＇ health in the future. The rising temperature exaggerates ozone pollution, but it is not clear whether climate change is aggravating or mitigating haze pollution. The transmission potential of malaria in South China will increase by 39%-140% and the transmission season will extend by 1 2 months with an air temperature increase of 1-2~C. By 2050, most areas in Hainan province are projected to convert from non-endemic dengue into endemic dengue areas. The aging population will cause more vulnerable people. To mitigate the adverse impacts of climate change on human health, sound and scientific adaptation strategies must be adopted in advance, such as strengthening the surveillance of epidemic diseases in potential transmission areas, conducting timely weather forecasting for human health, evaluating health vulnerability to climate change, improving environmental and health education, and strengthening hazard management and the cooperation between meteorological and health departments.

ANALYSIS OF CLINICAL CHARACTERISTICS AND DEATH RELATED FACTORS OF SEVERE MECONIUM ASPIRATION SYNDROME

Objective To investigate the factors in relation with the case fatality in severe meconium aspiration syndrome (MAS). Methods Eighty-one severe MAS cases intervened by the mechanical ventilation from 9 childrens hospitals were retrospectively analyzed for the risk factors of fatality with SAS software for non-parametric rank sum test and chi-square test. Results In the 81 cases, 49 were survived (death rate 39%). The gestational age (GA), Apgars score at 1min and other complications with MAS were significantly related to the death (P <0.05). There was no difference of death rate between the patients with or without receiving endotracheal intubation and airway suctioning (P>0.05). Conclusion A higher death rate (close to 40%) of severe MAS in the middle of 1990s in major cities of China suggests that it is important to detect the intrauterine hypoxemia as it may indicated by meconium staining amniotic fluid which should be intervened early by adequate termination of pregnancy before 42 weeks. The effects of delivery room suction and conventional ventilation also need to be reevaluated.

Emodin promoted pancreatic claudin-5 and occludin expression in experimental acute pancreatitis rats

AIM:To investigate the effect of emodin on pancreatic claudin-5 and occludin expression,and pancreatic paracellular permeability in acute pancreatitis(AP).METHODS:Experimental pancreatitis was induced by retrograde injection of 5% sodium taurocholate into the biliopancreatic duct.Emodin was injected via the external jugular vein 0 or 6 h after induction of AP.Rats from sham operation and AP groups were injected with normal saline at the same time.Samples of pancreas were obtained 6 or 12 h after drug administration.Pancreatic morphology was examined with hematoxylin and eosin staining.Pancreatic edema was estimated by measuring tissue water content.Tumor necrosis factor(TNF)-α and interleukin(IL)-6 level were measured by enzyme-linked immunosorbent assay.Pancreatic paracellular permeability was assessed by tissue dye extravasation.Expression of pancreatic claudin-5 and occludin was examined by immunohistology,quantitative real-time reverse transcriptase polymerase chain reaction and western blotting.RESULTS:Pancreatic TNF-α and IL-6 levels,wet/dry ratio,dye extravasation,and histological score were significantly elevated at 3,6 and 12 h following sodium taurocholate infusion;treatment with emodin prevented these changes at all time points.Immunostaining of claudin-5 and occludin was detected in rat pancreas,which was distributed in pancreatic acinar cells,ductal cells and vascular endothelial cells,respectively.Sodium taurocholate infusion significantly decreased pancreatic claudin-5 and occludin mRNA and protein levels at 3,6 and 12 h,and that could be promoted by intravenous administration of emodin at all time points.CONCLUSION:These results demonstrate that emodin could promote pancreatic claudin-5 and occludin expression,and reduce pancreatic paracellular permeability.

Clinical study on IL-8,TNF-α,T-cell subgroup in serum of patients with rectal cancer

Objective:The aim of our study was to investigate the immune status of patients with rectal cancer and its relationship with clinicopathological features.Methods:The serum levels of interleukin-8(IL-8),tumor necrosis factor(TNF-α) and T-cell subgroup contents were measured using a double-antibody sandwich assay of ELISA in 43 patients with rectal cancer,and compared with the normal health adults.Results:In patients with rectal cancer,the serum levels of CD4,CD4/CD8 of T-cell subgroup in peripheral blood were significantly lower than the control group(P < 0.01),which gradually decreased with increase of Dukes stage;but the levels of CD8,IL-8 and TNF-α were higher than the control group,which gradually increased with increase of Dukes stage.Conclusion:The immunocompromice exists in patients with rectal cancer,there is a correlation between the contents of T-cell subgroup,IL-8 and TNF-α in serum and the Dukes stage of rectal cancer.Therefore immunotherapy can be used in patients with rectal cancer.

Pneumocystis jiroveci pneumonia and pneumomediastinum in an anti-TNFαnaive patient with ulcerative colitis

We report the case of a 21-year-old man who was noted to have pneumomediastinum during an admission for an acute flare of ulcerative colitis. At that time, he was on maintenance treatment with azathioprine at a dose of 2.25 mg/kg per day, and had not received supplementary steroids for 9 mo. He had never received anti-tumor necrosis factor （TNF）α therapy. Shortly after apparently effective treatment with intravenous steroids and an increased dose of azathioprine, he developed worsening colitic and new respiratory symptoms, and was diagnosed with Pneumocystis jiroveci （carinii） pneumonia （PCP）. Pneumomediastinum is rare in immunocompetent hosts, but is a recognized complication of PCP in human immunodeficiency virus （HIV） patients, although our patient＇s HIV test was negative. Treatment of PCP with co-trimoxazole resulted in resolution of both respiratory and gastrointestinal symptoms, without the need to increase the steroid dose. There is increasing vigilance for opportunistic infections in patients with inflammatory bowel disease following the advent of anti-TNFα therapy. This case emphasizes the importance of considering the possibility of such infections in all patients with inflammatory bowel disease, irrespective of the immunosuppressants they receive, and highlights the potential of steroid-responsive opportunistic infections to mimic worsening colitic symptoms in patients with ulcerative colitis.

Competition between TRAF2 and TRAF6 Regulates NF-κB Activation in Human B Lymphocytes

Objective To investigate the role of TNF receptor-associated factor 2 (TRAF-2) and TRAF6 in CD40-induced nuclear factor-κB (NF-κB) signaling pathway and whether CD40 signaling requires TRAF2. Methods Human B cell lines were transfected with plasmids expressing wild type TRAF2 or dominant negative TRAF2,TRAF2-shRNA,or TRAF6-shRNA. The activation of NF-κB was detected by Western blot,kinase assay,transfactor enzyme-linked immunosorbent assay (ELISA),and fluorescence resonance energy transfer (FRET). Analysis of the role of TRAF-2 and TRAF-6 in CD40-mediated NF-κB activity was examined following stimulation with recombinant CD154. Results TRAF2 induced activity of IκB-kinases (IKKα,IKKi/ε),phosphorylation of IκBα,as well as nuclear translocation and phosphorylation of p65/RelA. In contrast,TRAF6 strongly induced NF-κB activation and nuclear translocation of p65 as well as p50 and c-Rel. Engagement of CD154-induced nuclear translocation of p65 was inhibited by a TRAF6-shRNA,but conversely was enhanced by a TRAF2-shRNA. Examination of direct interactions between CD40 and TRAFs by FRET documented that both TRAF2 and TRAF6 directly interacted with CD40. However,the two TRAFs competed for CD40 binding. Conclusions These results indicate that TRAF2 can signal in human B cells,but it is not essential for CD40-mediated NF-κB activation. Moreover,TRAF2 can compete with TRAF6 for CD40 binding,and thereby limit the capacity of CD40 engagement to induce NF-κB activation.

Retrospective analysis on acute respiratory distress syndrome in ICU

Objective： To assess the incidence, etiology, physiological and clinical features, mortality, and predictors of acute respiratory distress syndrome （ARDS） in intensive care unit （ICU）. Methods： A retrospective analysis of 5 314 patients admitted to the ICU of our hospital from April 1994 to December 2003 was performed in this study. The ARDS patients were identified with the criteria of the American- European Consensus Conference （ AECC ）. Acute physiology and chronic health evaluation Ⅲ （APACHE Ⅲ）, multiple organ dysfunction syndrome score （MODS score）, and lung injury score （LIS） were determined on the onset day of ARDS for all the patients. Other recorded variables included age, sex, biochemical indicators, blood gas analysis, length of stay in ICU, length of ventilation, presence or absence of tracheostomy, ventilation variables, elective operation or emergency operation. Resnits ： Totally, 131 patients （ 2. 5% ） developed ARDS, among whom, 12 patients were excluded from this study because they died within 24 hours and other 4 patients were also excluded for their incomplete information. Therefore, there were only 115 cases （62 males and 53 females, aged 22-75 years, 58 years on average ） left,accounting for 2. 2% of the total admitted patients. Their average ICU stay was （11.27±7.24） days and APACHE HI score was 17.23±7.21. Pneumonia and sepsis were the main cause of ARDS. The non-survivors were obviously older and showed significant difference in the ICU length of stay and length of ventilation as compared with the survivors. On admission, the non-survivors had significantly higher MODS and lower BE （base excess ）. The hospital mortality was 55. 7%. The main cause of death was multiple organ failure. Predictors of death at the onset of ARDS were advanced age, MODS≥8, and LIS ≥2.76. Conclusions： ARDS is a frequent syndrome in this cohort. Sepsis and pneumonia are the most common risk factors. The main cause of death is multiple organ failure. The mortality is high but similar to most recent series including severe comorbidities. Based on this patient population, advanced age, MODS score, and LIS may be the important prognostic indicators for ARDS.