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Based on the practical problem of fatigue life prediction of landing gear, the fatigue life prediction model of landing gear components with surface treatment was studied. The calculation process of the traditional local stress-strain method was introduced, and the factors that affect the local stress-strain method for fatigue life prediction were systematically explained; The actual engineering research shows that the main factors for predicting the fatigue life of landing gear by using the local stress-strain method are surface treatment and surface roughness. By modifying the strain-life curve, a model for predicting the fatigue life of landing gear components is proposed. The two calculation examples show that the predicted results are in good agreement with the experimental results, and the proposed method for revising the strain-life curves under different surface conditions is reasonable.

The landing gear of an aircraft bears a large impact load during landing, which causes the internal shock absorber to withstand high oil pressure and air pressure, and the buffer performance is greatly influenced. Firstly, based on the axial load of the buffer, the pressure formula of each cavity of the buffer is deduced. Then, the differential equation of the landing motion of landing gear is established by using the two mass system. Finally, the landing gear buffer pressure simulation model is built by using MATLAB/Simulink, which is used to analyze the variation of the pressure of each chamber with time and buffer stroke at different landing speeds, and the influence of oil chamber pressure on the cushioning performance with different oil return areas. The results show that, at different landing speeds, the pressure of each cavity presents a certain regularity at a specific moment of the landing process; the positive stroke oil return hole should not be too small, ensuring that the oil fills the oil return cavity, and the reverse stroke oil return hole cannot be too large to ensure that the oil fills the main oil chamber; the oil pressure in the buffer during landing process affects the stability of the plunger.

[Introduction] The paper aims to establish a sparseness approach based sample distribution for LS-SVM models to solve the problem of excessive computation in the application of classical iterative shearing sparseness algorithm for the soft measurement model of the carbon content in flying ash. [Method] On the basis of calculating the feature space distance between the samples, global representative indicator is constructed by mixing together the density and dispersion. The original samples were sorted and pruned and the sparsenseness was realized according to the indicator. The LS-SVM soft measurement model of the carbon content in fly ash was applied to a 1 000 MW coal-fired power plant, the original training sample set was taken from the field operation data of the unit. [Result] The results show that the proposed algorithm can greatly reduce the capacity of the training set with tiny loss of the error performance and it can reduce the training and online prediction calculation work during the LS-SVM soft measurement model of the carbon content in fly ash. [Conclusion] The LS-SVM sparse algorithm proposed in this paper reduces the sample space from 90 to 30, which not only reduces the calculation scale, but also guarantees the calculation accuracy, while guaranteeing that the error is reduced by 0.01%. The algorithm can realize on-line soft measurement of carbon content in fly ash in industrial controllers with limited computing performance such as PLC, and can be extended to other parameters soft measurement systems in power plants.

Objective: To explore the relationship between the onset time of sepsis-associated acute kidney injury (SA-AKI) and adverse clinical outcomes. Methods: Data were derived from Beijing Acute Kidney Injure Trial (BAKIT) which investigated the epidemiology of acute kidney injury (AKI) in critically ill patients at 30 intensive care units (ICU) of 28 tertiary hospitals in Beijing from 1 March to 31 August 2012. Patients who were older than 18 years and diagnosed with sepsis and AKI, and expected to stay in ICU for at least 24 h were included in this study. A total of 653 patients were included in this study, 414 males and 239 females with a mean age of (68.2±17.0) years. According to the onset time of SA-AKI, patients were grouped into early AKI (E-AKI) (AKI occurred within 48 hours after ICU admission) and late AKI (L-AKI) (AKI occurred after 48 hours of ICU admission) group. The primary outcome was major adverse kidney events (MAKE), consisted of all-cause mortality, renal replacement therapy-dependence, and an inability to recover to 1.5 times of the baseline creatinine value up to 30 days. Multivariable logistic regression was used to investigate the association between the onset time of SA-AKI and clinical outcomes. Results: A total of 653 patients with SA-AKI were included, 423 (64.8%) patients developed E-AKI, 230 (35.2%) cases developed L-AKI, MAKE occurred in 405 (62.0%) cases, and 301 (46.1%) patients died in hospital. Compared with E-AKI group, L-AKI patients showed higher AKI 3 level rate [55.7%(128/230) vs 40.2%(170/423), P <0.001], incidence of MAKE [72.6%(167/230) vs 56.3%(238/423, P <0.001)] and hospital mortality [55.2%(127/230) vs 44.1%(174/423), P =0.001]. The risk of MAKE and in-hospital mortality in L-AKI group increased for 2.55-fold times ( OR =3.55, 95% CI : 1.94-6.04) and 1.84-fold times ( OR =2.84, 95% CI : 1.44-5.60) when compared with those in E-AKI, respectively (both P <0.05). Conclusion: Late timing onset of SA-AKI is associated with poor clinical outcomes.

Objective: To investigate dose-response associations between fluid overload (FO) and hospital mortality in patients with sepsis. Methods: The current cohort study was prospective and multicenter. Data were derived from the China Critical Care Sepsis Trial, which was conducted from January 2013 to August 2014. Patients aged≥18 years who were admitted to intensive care units (ICUs) for at least 3 days were included. Fluid input/output, fluid balance, fluid overload (FO), and maximum FO (MFO) were calculated during the first 3 days of ICU admission. The patients were divided into three groups based on MFO values: MFO<5%L/kg, MFO 5%-10%L/kg, and MFO≥10% L/kg. Kaplan-Meier analysis was used to predict time to death in hospital in the three groups. Associations between MFO and in-hospital mortality were evaluated via multivariable Cox regression models with restricted cubic splines. Results: A total of 2 070 patients were included in the study, of which 1 339 were male and 731 were female, and the mean age was (62.6±17.9) years. Of 696 (33.6%) who died in hospital, 968 (46.8%) were in the MFO<5%L/kg group, 530 (25.6%) were in the MFO 5%-10%L/kg group, and 572 (27.6%) were in the MFO≥10%L/kg group. Deceased patients had significantly higher fluid input than surviving patients during the first 3 days [7 642.0 (2 874.3, 13 639.5) ml vs. 5 738.0 (1 489.0, 7 153.5)ml], and lower fluid output [4 086.0 (1 367.0, 6 354.5) ml vs. 6 130.0 (2 046.0, 11 762.0) ml]. The cumulative survival rates in the three groups gradually decreased with length of ICU stay, and they were 74.9% (725/968) in the MFO<5% L/kg group, 67.7% (359/530) in the MFO 5%-10%L/kg group, and 51.6% (295/572) in the MFO≥10%L/kg group. Compared with the MFO<5%L/kg group, the MFO≥10%L/kg group had a 49% increased risk of inhospital mortality ( HR =1.49, 95% CI 1.28-1.73). For each 1% L/kg increase in MFO, the risk of in-hospital mortality increased by 7% ( HR =1.07, 95% CI 1.05-1.09). There was a"J-shaped"non-linear association between MFO and in-hospital mortality with a nadir of 4.1% L/kg. Conclusion: Higher and lower optimum fluid balance levels were associated with an increased risk of in-hospital mortality, as reflected by the observed J-shaped non-linear association between fluid overload and inhospital mortality.

Objective: To explore the incidence and clinical characteristics of engraftment syndrome (ES) after syngeneic hematopoietic stem cell transplantation (syn-HSCT) in patients with hematological diseases. Methods: The clinical data of 21 patients who received syn-HSCT at People's Hospital of Peking University from January 1994 to May 2018 were retrospectively analyzed. Results: Seven (33.3% ) of 21 patients developed ES. The onset of ES symptoms occurred at a median of 8 (range: 5-13) days after HSCT, and the diagnosis of ES occurred at a median of 10 (range: 7-14) days after HSCT. Steroids were administered immediately after the diagnosis of ES, the median time of symptom continuance was 2 (range: 1-5) days, and all patients showed complete resolution of ES symptoms. In the multivariate analysis, patients with acute myeloid leukemia and faster neutrophil reconstitution were the risk factors for ES ( HR =15.298, 95% CI 1.486-157.501, P =0.022, and HR =17.459, 95% CI 1.776-171.687, P =0.014) . Meanwhile, there was no significant difference in the overall survival and disease-free survival between patients with ES and those without ES. Conclusion: A high incidence of ES was observed in syn-HSCT recipients. Moreover, the prognosis of ES was excellent.

Objective: To identify clinical subphenotypes of sepsis by clinical variables, and the association between fluid balance (FB) and outcomes in sepsis patients with different subphenotypes. Methods: Data were derived from China Critical Care Sepsis Trial. A total of 2 075 patients were included in the study, with a mean age of (62.5±17.4) years, 1 362 (65.6%) were male, 713 (34.3%) were female. In-hospital mortality was the primary outcome. Clinical variables were entered into the latent profile analysis (LPA) model which was used to identify the subphenotypes of sepsis. Multivariable logistic regression model was used to explore the association of FB on the first 2 days admitted to ICU and in-hospital mortality. Results: Total of 687 (33.1%) patients died in the hospital. Four subphenotypes of sepsis were identified by the PLA model: 1 421 (68.5%) patients were identified as profile 1, which was characterized by the lowest in-hospital mortality (28.3%, 402/1 421) and was considered as the baseline subphenotype; profile 2 was characterized by multiple organ dysfunction(232, 11.2%); profile 3 was characterized by respiratory dysfunction (196, 9.4%) and profile 4 was characterized by kidney injury/failure (226, 10.9%). Profile 2 showed the highest in-hospital mortality (54.3%, 126/232), followed by profile 4 (39.4%, 89/226), profile 3 (35.7%, 70/196). Profile 2 had the highest FB of 68.5(34.7, 89.4)ml/kg on day 1 and decreased rapidly to 29.4(13.6, 49.8) ml/kg on day 2. Multivariable analysis showed that for every 10 ml/kg of FB increased on the first 48 hours admitted to ICU, the risk of in-hospital mortality decreased 14% ( OR =0.86, 95% CI : 0.81-0.97) in profile 2, and increased 4% ( OR =1.04, 95% CI :1.02-1.07) in profile 4. However, there were no significant association between FB on the fist 2 days admitted to ICU and the risk of in-hospital mortality in profile 1 ( OR =1.06, 95% CI : 0.94-1.19)and in profile 3 ( OR =0.99, 95% CI : 0.94-1.05). Conclusions: Four subphenotypes of sepsis were identified according to the clinical variables, which showed different characteristics, distributions, outcomes and responses to fluid balance.

Objective: To explore the association between glucose variability and poor prognosis in critically ill patients., Methods: This prospective study was undertaken in a 24-bed intensive care unit (ICU). A total of 145 patients staying for over 24 hours in ICU were enrolled. Their arterial levels of blood glucose were measured four times daily routinely. And the mean glucose level (MGL), standard deviation (SD) and coefficient of variation (CV) were calculated. The incidence of moderate hypoglycemia (MH), severe hypoglycemia (SH), total dosage of hormone, average daily dosage of insulin, duration of renal replacement- therapy (RRT), mechanical ventilation and ICU free days were also recorded. They were divided into survival (n = 85) and nonsurvival (n = 60) groups according to survival or not at 28 days. And CV was compared between two groups and the relationship of CV and mortality examined., Results: The nonsurvival group had higher CV value accompanied by higher RRT proportion, higher incidences of MH and SH, shorter free mechanical ventilation time and free ICU stay. The higher CV value was found in surviving nondiabetics. However, no significant difference existed in diabetes group., Conclusion: Critically ill patients have higher CV of glucose variability especially in non-diabetic patients. Blood glucose fluctuations denote a worse prognosis. And hypoglycemia should raise a high alert. Frequent blood glucose monitoring is beneficial to detecting the changes of condition and adjusting treatment regimens accordingly.

Objective: To identify the effect of XW630 on the expression of type I collagen in the epiphyseal plates of mice., Methods: The immunohistochemical method was used to measure the change of type I collagen protein after being treated with XW630., Results: With 10(-7) mol/L or 10(-7) mol/L of XW630, the area of positive stain cells in every zone increased significantly compared to the control group. A more significant increase of the area of positive cells in the proliferative zone and hypertrophic zone was observed in the XW630 group than in the estrone group at a concentration of 10(-7) mol/L. When the XW630 was decreased to 10(-9) mol/L, the increase of positive cells was only found in the hypertrophic zone. The area of positive cells increased with the concentration of XW630., Conclusion: The XW630 upregulates the dose-dependent expression of type I collagen protein in the resting zone, proliferative zone, and hypertrophic zone in the epiphyseal plates of mice in vitro.

Objective: To investigate the physiological role of fragile X mental retardation protein (FMRP) and screen the proteins interacting with FMRP in human fetal hippocampus cDNA library., Methods: Human fetal hippocampus cDNA library was constructed in yeast two-hybrid DAD vector pGAD10. Quality of the library was measured by picking up random colonies as templates for PCR testing. Proteins interacting with FMRP were screened by yeast two-hybrid system. Furthermore, the interaction site of FMRP was mapped in yeast., Results: The average length of inserts of the two-hybrid library was 1.5 kb, and the ratio of recombinant colonies was about 90%. Human NDK/Nm23-H2 was found interacting with FMRP. NDK/Nm23-H2 interacted with FMRP exon 1-12, as well as FMRP isoforms without exon 12, and exons 14-17. NDK/Nm23-H2 couldn't interact with FMRP exon 1-6 and exon 2-7 fragments., Conclusions: Human NDK/Nm23-H2 can bind FMRP directly. The interaction site of FMRP is located at its exon 1-11. This interaction in vitro might alter the intracellular distribution of NDK/Nm23-H2, and even regulates the transcription and expression of FMRP.

Objective: To analyze the interactions between domains within the NH2- and COOH-terminal regions of presenilins., Methods: The various constructions corresponding to NH2-terminal fragment (NTF) and COOH-terminal fragment (CTF) derivatives of presenilin 1 (PS1) and presenilin 2 (PS2) were generated by RT-PCR, and their interactions were assayed by yeast two-hybrid system., Results: Domains within the NH- and COOH-terminal fragments of presenilins could directly interact with each other, and therefore form high molecular weight complex. The interaction site between domains within PS1 located at amino acid 361-447 of PS1 CTF, without the involvement of other partners. Similar interaction was not observed between PS11-360 and PS2341-448, PS2(1)-340 and PS1(361)-467., Conclusions: Intramolecular interaction between domains within the NH2- and COOH-terminal regions of presenilins may be critical to the folding and assembly of mature PS molecules.

Objective: To investigate the reconstructional method of posterior wall of vagina after the resection of rectum carcinoma., Methods: From August 1991 to March 1996, 10 patients with rectum carcinoma were adopted in this study, among them, there were 4 cases belong to B stage of Dukas, and 6 cases belong to C stage of Dukes. In operation, rectum carcinoma and posterior wall of vagina were resected, and concurrent reconstruction was finished by using pedicled muscular flap of uterus., Results: The effect of operation were satisfactory except one case who was failed because of insufficient blood supply of the flap. Followed-up for 3-6 months, the posterior wall of vagina healed in 7 cases, the width of vagina was 2-3 fingers and the depth was 5-6 cm., Conclusion: Reconstruction of the posterior wall of vagina with pedicled muscular flap of uterus was available in clinic. For its simplicity and feasibility, it's suitable for the resection of rectum carcinoma in which the posterior wall of vagina was infiltrated.

From 1983 to 1985, 214 patients with rectal carcinoma were assessed for the conformation rate of the rectal examination to the gross findings of the extent of perirectal infiltration in the resected specimens. It was found that the conventional classification of the extent of rectal infiltration by rectal examination, 1/4, 1/3, 2/4, 3/4 and 4/4 of the circumference, had only a conformation rate of 32.7% to the gross findings. According to the classification of 1/4 or less and more, the conformation rate could reach 93%. It was also found that the extent of perirectal infiltration, being closely related to the regional lymph node metastasis and the depth of invasion, was only demonstrated by this latter classification, which was not shown in the conventional classification. Hence, it is suggested that the rectal examination implying the extent of perirectal infiltration by simply classified into two groups: equal to or less than 1/4 and more than 1/4 of the circumference of the rectal wall.