Theoretical study of the effects of alloying elements on TiO2/Ti2AlNb interface adhesion properties.

Ti2AlNb-based alloys are expected to be applied in the manufacture of parts of aeroengines to achieve the goal of increasing the thrust-to-weight ratio. However, the poor high temperature oxidation resistance of these alloys may hinder their applications. Alloying has been proven to be effective in improving oxidation resistance properties. However, the selection of alloying elements and their influence mechanisms are rarely studied. The TiO2/Ti2AlNb interface bonding interactions and the effects of alloying elements of Si, Sc, Y, Zr, Mo and Hf were investigated via first principles calculations. The separation energy and electronic structure were studied to explore the bonding interactions between the oxide scale and Ti2AlNb matrix. When Zr and Hf are used to replace Al, the bonding properties of the TiO2/Ti2AlNb interface are improved. The tensile and shear deformations of the interfacial zones are applied to study the influence of alloying elements on the TiO2 oxide spalling on Ti2AlNb. The tensile strength is increased by more than 2 GPa when Nb is substituted by the Sc, Zr and Hf elements. Therefore, Sc, Zr, and Hf are beneficial for inhibiting oxide spalling and will have great potential to improve the oxidation resistance properties.

[Clinical characteristics and prognostic factors of patients with anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis associated interstitial lung disease].

Objective: To analyze the clinical characteristics and prognostic factors of patients with anti-melanoma differentiation-associated gene 5 (anti-MDA5)-positive dermatomyositis associated interstitial lung disease (DM-ILD). Methods: The patients with MDA5+DM-ILD who were admitted to Department of Respiratory Medicine, Nanjing Drum Tower Hospital from January 2017 to March 2021 were enrolled. The clinical data and survival information were analyzed retrospectively. Patients were divided into survival group or death group, and rapid progressive ILD (RP-ILD) group or non-rapid progressive ILD group, according to their survival status and clinical progression. Results: A total of 105 patients with anti-MDA5+DM-ILD (median age of onset 54 years) were enrolled, 58% being female (61 cases). The main sub-type of dermatomyositis was amyopathic dermatomyositis (n=74, 70%), followed by dermatomyositis (n=31, 30%). The main extrapulmonary manifestations were skin lesions (n=60, 57.1%), muscle manifestations(n=20, 19%) and arthralgia/arthritis (n=20, 19%). 15.4% of the patients had positive ANA (antibody titer≥1∶320), and 61.9% of the patients had anti-RO-52 kDa antibody. A total of 66 patients (62.8%) developed RP-ILD, and 58 patients (56.3%) died. Lower oxygenation index (OR=0.974, 95%CI:0.954-0.994, P=0.012) and no joint pain (OR=0.032, 95%CI: 0.002-0.663 P=0.026) were independent risk factors for RP-ILD. Cox regression analysis showed that RP-ILD (HR=3.194, 95%CI:1.025-9.954, P=0.045), older than 53 years (HR=3.450, 95%CI: 1.388-8.577, P=0.008), ferritin level more than 1 330.5 ng/ml (HR=3.032, 95%CI 1.208-7.610, P=0.018) and C-reactive protein (CRP) above 16.95 mg/L (HR=2.794, 95%CI:1.102-7.084, P=0.030) were independent predictors of mortality. Conclusions: The clinical manifestations of patients with anti-MDA5+DM-ILD presenting to the respiratory department were heterogeneous, with most being amyopathic dermatomyositis, and both the incidence of RP-ILD and the risk of death were high. Even in the absence of associated rash, joint, or muscle manifestations, anti-MDA5 antibody screening should be considered in patients with rapidly progressive ILD who were negative on baseline autoantibody screening but positive for anti-RO52kDa antibody.

[Fibrinogen gamma-chain mutation, p.Ile171His, leads to hereditary hypofibrinogenemia].

Objective: To explore the clinical phenotype and genotype of a family with hereditary hypofibrinogenemia. Methods: Activated partial thrombin time (APTT), prothrombin time (PT),thrombin time (TT) and thrombelastogram (TEG) were tested in all family members. Fibrinogen activity and antigen were detected by Clauss method and immunoturbidimetric method respectively. All exons and flanking sequences of fibrinogen FGA,FGB,FGG genes were analyzed by PCR, and the products were subjected to Sanger sequencing. Results: The proband represented prolonged PT and TT, low Fg activity and antigen, elevated K value and decreased Angle value in TEG. Other family members reported similar changes including proband's father,daughter and son, and his elder brother and his niece. Exon 5 c.510_512 of FGG gene in the proband revealed a minor deletion mutation. Conclusion: The novel heterozygous missense mutation of exon 5 c.510_512del (Gln170_Ile171 del ins His) of FGG gene is the molecular mechanism that leads to hereditary hypofibrinogenemia in this family.

[Consistency analysis and clinical guiding significance of cytomegalovirus nucleic acid and antibody detections in patients with different clinical characteristics].

OBJECTIVE: To investigate the consistency of cytomegalovirus deoxyribo nucleic acid (CMV-DNA) and immunoglobulin M (IgM) antibody detections in patients with different clinical characteristics and their guiding value for clinical practice. METHODS: From December 2014 to November 2019, a total of 507 patients who were detected with both CMV-IgM and CMV-DNA were collected in Peking University International Hospital. Their general information, such as gender, age and clinical data, including the patient's diagnosis, medication, and outcome were also collected. The groups were stratified according to whether CMV-DNA was negative or positive, CMV-IgM was negative or positive, age, gender, and whether they received immunosuppressive therapy or not. The Pearson Chi-square test or Fisher's exact test was used for comparison of the rates between the groups. P < 0.05 means the difference is statisti-cally significant. RESULTS: Of the 507 patients submitted for examination, 55 (10.85%) were positive for CMV-DNA, 74 (14.60%) were positive for CMV-IgM, and 20 (3.94%) were positive for both CMV-DNA and CMV-IgM. Of the 55 patients with CMV-DNA positive, 37 were male, accounting for 67.27%. In addition, 25 patients were older than 60 years, accounting for 45.45% and 33 patients received immunosuppressive therapy, accounting for 60%. The rates were higher than that of CMV-DNA negative group, 47.35% (P=0.005), 68.14% (P=0.043), 46.02% (P=0.050), respectively. Of the patients with both CMV-DNA and IgM positive, 45% received immunosuppressive threapy, which was lower than that of CMV-DNA positive but IgM negative patients (68.57%, P=0.086), and also lower than CMV-DNA negative but IgM positive patients (68.52%, P=0.064). In the patients with both CMV-DNA and IgM positive, 91.67% showed remission after receiving ganciclovir, whereas in the patients with CMV-DNA positive but IgM negative, the rate was only 60% (P=0.067). CONCLUSION: CMV-IgM antibody detection is affected by age, gender, and immune status. It is not recommended to use CMV-IgM alone to determine CMV infection in patients with immunosuppressive status and those older than 60 years. CMV-DNA and CMV-IgM combined detection may help to predict patients' immune status and outcomes of antiviral therapy.

[Idiopathic pleuroparenehymal fibroelastosis: five case reports and review of literature].

Objective: To raise the awareness of idiopathic pleuroparenehymal fibroelastosis (iPPFE) through investigating the clinical, radiographic and pathological features. Methods: Five cases of iPPFE proved by pathology. The clinical data were studied respectively, and the relevant literature was reviewed. Results: All the cases of iPPFE were manifested by cough and dyspnea. The patients including 3 males and 2 females, aged from 30 to 70 years Chest CT scan showed pleural thickening, subpleural consolidation in both upper lungs complicated with tractive bronchiectasis.Computed tomography-guided percutaneous lung biopsy or surgical lung were performed and the same pathological showed pleura and subpleural dense elastic and collagen fibers. The elastic fibers stain was also positive,which was consistent with PPFE. One patient received low-dose corticosteroid, two received pirfenidone therapy, the others received no treatment. Three patients were stable during the follow-up. Conclusions: iPPFE has characteristic pathological features. However, the number of clinically reported cases is low due to missed diagnosis or misdiagnosed. Improving the understanding of features of iPPFE is helpful for the dianosis, therapy, and prognosis of this disease.

Functionalized M2TiC2Tx MXenes (M = Cr and Mo; T = F, O, and OH) as high performance electrode materials for sodium ion batteries.

First-principles calculations were performed to study the electrochemical performance of M2TiC2 (M = Cr or Mo) and M2TiC2Tx (T = O, F or OH) used as anode materials for sodium ion batteries (SIBs). The O functionalized MXenes (Cr2TiC2O2 and Mo2TiC2O2) are found to be more stable than F and OH terminated systems. The diffusion performance of sodium in MXene materials is mainly affected by the functional groups. The lowest diffusion barrier of functionalized MXenes is about one order larger in magnitude than that of bare MXenes. Although the introduction of O-groups hinders the diffusion of sodium, it can greatly improve the theoretical storage capacities. Meanwhile, the diffusion paths and diffusion energy barriers of Na are affected by Na concentration effects, while the interactions between terminations have little effect. Furthermore, multiple layers of sodium atoms are found to be adsorbed between the layers of M2TiC2O2, thus significantly increasing the theoretical capacities. The theoretical sodium storage capacities of M2TiC2O2 monolayers reach 515.70 mA h g-1 (M = Cr) and 362.46 mA h g-1 (M = Mo) and the OCVs can approach 0.034 V (M = Cr) and 0.042 V (M = Mo). Therefore, Cr2TiC2O2 and Mo2TiC2O2 are expected to be promising anode materials for SIBs due to their excellent properties, such as good electronic conductivity, low sodium diffusion barrier, and high theoretical sodium storage capacity.

[Rush poppers use and risks of human papillomavirus infection among men who have sex with men in Urumqi: mediation effect through high-risk sexual behaviors].

Objective: To study the prevalence of rush poppers use among men who have sex with men (MSM) in Urumqi and to analyze the mediating effect of high-risk sexual behavior between the use of rush poppers and human papillomavirus (HPV) infection. Methods: From January to June 2018, 651 MSM were recruited through network and publicity. Data was collected by using online questionnaire and anal swab were collected from them for HPV genotyping. According to Baron and Kenny's criterion, multivariate logistic regression models was used to analyze the mediation effect of high-risks sexual behaviors (multiple sexual partners, anal intercourse condom use) between rush poppers use and HPV infection. Results: A total of 651 subjects were (32.0±8.0) years old, and 174 subjects (26.7%) had ever used rush poppers in the past 6 months, while 350 subjects (46.9%) had more than 2 sexual partners and 188 subjects (28.9%) did not use anal condom. After adjusting age and marital status, rush poppers use was associated with HPV infection (OR (95%CI) was 2.34 (1.63-3.36), P<0.05), and sexual partners in the past 6 months (OR (95%CI) was 2.72 (1.89-3.93), P<0.05).After adjustment for age, marital status, sexual partners in the past 6 months, and anal condom use, rush poppers use was still associated with HPV infection (OR (95%CI) was 2.21 (1.53-3.19), P<0.05).After adjustment and adjustment of age, marital status, rush poppers use and anal sex condom use, the number of sexual partners at nearly 6 months was still associated with HPV infection (OR (95%CI) was 1.46 (1.05-2.04), P<0.05). Conclusion: Sexual partners in the past 6 months have a mediation effect between rush poppers use and HPV infection in Urumqi. For the prevention of sexually transmitted diseases, we should focus on rush poppers use.

[Clinical effect of minimally-Invasive surgical-transforaminal lumbar interbody fusion technique associated with percutaneous pedicle screws in micro endoscopy discectomy].

Objective: To evaluate the clinical efficacy between the minimally-Invasive surgical (MIS)-transforaminal lumbar interbody fusion (TLIF) technique associated with percutaneous pedicle screws in micro endoscopy discectomyand MIS-TLIF technique associated with both sides of the lower lumbar spine Wiltse approach in Quadrant channel with treatment of single segment herniation associated with lumbar instability syndrome. Methods: From January 2012 to January 2015, 75 cases that meet the inclusion and exclusion criteria were treated by retrospective study method, which were divided into two groups in Department of Orthopedics, the Affiliated Hospital of Putian University.Experimental group(30 patients) were treated with MIS-TLIF technique associated with percutaneous pedicle screws in microendoscopy discectomy, control group were treated with MIS-TLIF technique associated with both sides of the lower lumbar spine Wiltse approach in Quadrant Chanel.Compare operation time, blood loss, postoperativehospital stay, clinical efficacy, nailing accuracy, fusion rate, postoperative pain scoring of two groups. Results: The blood loss[(102.1±5.5) min vs(103.7±7.7) min, t=-0.586, P>0.05], postoperative blood loss, hospital stay[(44.6±5.2) ml and(57.2±5.3) ml, (7.3±1.6) d and(9.3±1.9) d; t=-5.813, -2.774, P<0.05], JOA score before and after surgery in same group were statistically significant(P<0.05), respectively.Patients of two groups compared with operation time, clinical efficacy, nailing accuracy[group A: 97.5%, group B: 95.7%; χ(2)=3.00, P>0.05.Postoperative 3 month , group A: 96.7%(29/30), group B: 94.3%(33/35; χ(2)=0.79, P>0.05], fusion rate[group A: 96.7%(29/30), group B: 94.3%(33/35), χ(2)=0.79, P>0.05], preoperative JOA score[(20.4±2.4)score and(7.9±1.0), (19.1±2.7)score and(7.8±1.2)score], postoperative JOA score were no statistically significant respectively, P>0.05. JOA score of both groups were statistically significant respectively Before and after operate.Excellent rate: group A; 84.4%(25/30), group B: 80.0%(28/35), χ(2)=0.43, P>0.05. Conclusion: MIS-TLIF technique associated with percutaneous pedicle screws in micro endoscopy discectomy relative to conventional minimally invasive spine surgery had many advantages: minimal damage, operation conveniently, precisely clinical effect, that is a kind of feasible and reliable minimally invasive surgery which is worth promoting.

[Pulmonary intravascular large B-cell lymphomamanifesting as interstitial pneumonias: report of 2 cases and review of literature].

Objective: To investigate the clinical, radiographic characteristics and prognosis of pulmonary intravascular large B-cell lymphoma(IVLBCL) manifesting as interstitial pneumonias on HRCT. Methods: A retrospective analysis was carried out on clinical data of 2 patients with pulmonary IVLBCL admitted to the Affiliated Drum Tower Hospital of Nanjing University from March 2010 to May 2012. A literature research was performed with "pulmonary intravascular lymphoma" as the key word in Wanfang Database, China Knowledge Resource Integrated Database and Pubmed. The time interval was from January 1980 to June 2015. Related articles of pulmonary IVLBCL were retrieved and the clinical, radiographic characteristics and prognosis were analyzed. Results: The first patient was a 69 year-old female presenting with ground-glass opacities, interlobular septal thickening and patchy consolidation on HRCT, for whom the diagnosis was confirmed by transbronchial lung biopsy (TBLB). The second patient was a 70 year-old male presenting with diffuse ground-glass opacities on HRCT, and the diagnosis was made by pathology on video-assisted thoracoscopic biopsy. The 2 patients all presented with dyspnoea, cough, fever and elevated lactate dehydrogenase(LDH). The pathological study of lung biopsy specimen demonstrated invasion of atypical lymphocytes into small vessels and capillaries. The tumor cells were positive for CD(20).Literature review found 19 articles, all case reports with a total of 22 patients. Conclusions: The clinical manifestation of pulmonary IVLBCL was nonspecific and the disease progressed rapidly. For patients with interstitial pneumonias on HRCT, pulmonary IVLBCL needed to be considered as a differential diagnosis and pathological studies should be obtained as soon as possible, so that better prognosis could be archived through early intervention.

[Intraocular lens power calculation for high myopic eyes with cataract: comparison of three formulas].

Objective: To compare the accuracy of three different formulas for intraocular lens power calculation in high myopic eyes with cataract and analyze their influencial factors. Methods: One hundred and three high myopic patients of cataract (103 eyes), with average age of 60.2±8.8 years old (39.0-77.0), including 45 male and 54 female and with axial length ≥ 26 mm were enrolled in this retrospective case-series study. All of them underwent routine ocular examination and IOLMastermeasurement preoperatively and then underwent phacoemulsification through temporal clear-corneal incision with implantation of HumanOptic posterior chamber Intraocular lens (IOL). All analyses were conducted using SPSS version 19.0. Repeated-measures analysis of variance was applied to compare the refractive results one month postoperatively with the predicted IOL powers calculated by SRK/T, Holladay 1, or Haigis formula before surgery. The differences were further compared based on different grouping of axial length (AXL), corneal curvature (K) and corneal astigmatism (CA). The accuracies of the three formulas were analyzed using Bland-Altman analyses and the possible error sources of each formula were analyzed using multiple regression model. Results: The majority of patients enrolled had hyperopic shift after cataract surgery. The mean errors (ME) of the three formulas were SRK/T: 0.70±0.89D, Holladay 1: (1.20±0.88) D and Haigis: (0.60±0.88) D; the mean absolute errors (MAE) of the three formulas were (0.81±0.79) D, (1.23±0.84) D and (0.76±0.74) D, respectively. Both ME and MAE of Holladay formula were significantly greater than the other two formulas (F=86.31, P<0.01). Besides, the proportion of patients having a prediction error within 0.50 D was lower in those using Holladay formula (20.4%, 21/103) than the other two (SRK/T: 38.8%, 40/103, χ(2)=8.41, P<0.01, Haigis: 45.6%, 47/103, χ(2)=14.84, P<0.01). Bland-Altman analyses showed that the accuracies of all the three formulas were acceptable in patients of cataract with high myopia in clinical practice. ME and MAE tended to be larger with longer axial length, larger corneal curvature and astigmatism of the patients in all three formulas. However, in eyes with axial length> 30 mm or corneal curvature ≤43.00 D, the MAE of Haigis formula was lower than that of SRK/T formula (F=63.26,63.94, both P<0.01). The prediction error of SRK/T formula was positively correlated with axial length and corneal astigmatism (F=33.97, r=0.66, ß=0.48, P<0.01 and ß=0.42, P<0.01), while for Holladay and Haigis formulas, in addition to the previous two factors, the errors were also positively correlated with mean corneal curvature (Holladay 1: F=31.26, r=0.72, AXL: ß=0.52, P<0.01, K: ß=0.20, P<0.05 and CA: ß=0.37, P<0.01; Haigis: F=30.96, r=0.72, AXL: ß=0.33, P<0.01, K: ß=0.40, P<0.01 and CA: ß=0.37, P<0.01). Conclusions: In the selection of IOL formula for high myopic patients with cataract, Haigis or SRK/T would reduce the prediction error and serve as the more accurate formulas than Holladay 1. Haigis formula may be more accurate than SRK/T formula in case of AXL>30 mm or K≤43.00 D. (Chin J Ophthalmol, 2017, 53: 260-265).

First principles study on stability and hydrogen adsorption properties of Mg/Ti interface.

The hydrogenation and stability properties of the Mg/Ti interface are studied by first-principles calculations. The strain of lattice and movement of ions were imposed to search for a stable Mg/Ti interface. The anti-symmetrical configuration was found to be the most stable. The easiest transition pathway from anti-symmetrical to symmetrical configuration may be through the diagonal direction with no energy barrier. The hydrogen adsorption at distinguished positions in the Mg/Ti interface is investigated. The negative hydrogen adsorption energy reaches -0.991 eV at the top site in the interface, which will highly favor the thermodynamic stability of the Mg/Ti interface. The electronic structure is studied and it was found that the Ti acts as a hydrogen atom 'capturer' and strong interactions between H and its surrounding Ti and Mg atoms are expected. Thus, inserting Ti layers could create an interfacial zone where the adsorptions of hydrogen atoms may get stabilized and therefore improve the hydrogen storage properties of Mg.

Effects of Omega-3 fatty acid on major cardiovascular events and mortality in patients with coronary heart disease: a meta-analysis of randomized controlled trials.

AIM: There is considerable discrepancy regarding the protective effects of Omega-3 polyunsaturated fatty acids (Omega-3 PUFAs) in patients with coronary heart disease (CHD) from the early-phase clinical randomized controlled trials (RCTs). We conducted a meta-analysis of RCTs to address this issue. DATA SYNTHESIS: Pubmed, the Cochrane Central Register of Controlled Trials, and EMBASE databases (∼ May 2013) were systematically searched. Odds ratios (OR) and associated 95% CI were retrieved by using random-effect model according to heterogeneity. A total of 14 RCTs involving 16,338 individuals in the Omega-3 PUFAs group and 16,318 in the control group were identified. Patients assigned to Omega-3 PUFAs did not demonstrate satisfactory improvements on major cardiovascular events (OR, 0.93; 95% CI, 0.86 to 1.01; P = 0.08; I(2) = 46%). By contrast, the reduced risks of death from cardiac causes, sudden cardiac death and death from all causes (OR, 0.88; 95% CI, 0.80 to 0.96; P = 0.003; I(2) = 0%; OR, 0.86; 95% CI, 0.76 to 0.98; P = 0.03; I(2) = 29%; and OR, 0.92; 95% CI, 0.85 to 0.99; P = 0.02; I(2) = 6%; respectively) were shown. CONCLUSIONS: Supplement of Omega-3 PUFAs in patients with CHD is not associated with a protective effect on major cardiovascular events, while it does exert beneficial effects in reducing death from cardiac causes, sudden cardiac death and death from all causes. However, with currently available cardio-protective therapies, whether dietary supplementation with Omega-3 PUFAs should be still considered in patients with CHD is currently debated.

Effect of inhaled MgSO4 on FEV1 and PEF in children with asthma induced by acetylcholine: a randomized controlled clinical trail of 330 cases.

OBJECTIVES: To determine the response of nebulized magnesium sulfate on the lung function of acetylcholine-induced asthma children. METHODS: Three hundred and thirty children of asthma with positive bronchial provocation test were randomly divided into three groups: magnesium sulfate, albuterol, and a combination of magnesium sulfate and albuterol. Lung function was compared between the three groups. RESULTS: Forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) as percentage over predicted at 10 min and 20 min in albuterol and combination group were significantly improved when compared to magnesium group. The changes in FEV1 and PEF expressed as absolute and percentage over predicted was not statistically significant from baseline to 20 min in magnesium, albuterol, and combination of magnesium sulfate and albuterol. There was no significant adverse effect observed during the present study. CONCLUSION: Nebulized magnesium sulfate alone has a bronchodilatory effect in Ach-induced asthmatic children. The combination of MgSO4 and albuterol did not has a synergistic effect.

Single nucleotide polymorphisms in the ORM1-like 3 gene associated with childhood asthma in a Chinese population.

Single nucleotide polymorphism (SNP)-based genome-wide association studies have revealed that polymorphisms of the ORM1-like 3 (ORMDL3) gene are associated with childhood asthma. We investigated genetic associations of SNPs in and around the ORMDL3 gene with childhood asthma in a Chinese population. Genomic DNA was extracted from peripheral venous blood drawn from 152 subjects with childhood asthma and from 190 control subjects. SNP genotyping was performed with the MassARRAY system (Sequenom) by means of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Among the six SNPs, only the genotype frequencies of rs7216389 were significantly different between asthmatic children and controls. Asthmatic children had a significantly higher frequency of T alleles [odds ratio (OR) = 1.653, 95% confidence interval (95%CI) = 1.170-2.333] in rs7216389, than controls. The TT genotype of rs7216389 was found to be a significant risk factor for childhood asthma by logistic regression analysis (OR = 1.704, 95%CI = 1.105-2.628). There was no significant association between the TT genotype of rs7216389 and clinical features of childhood asthma. We conclude that the ORMDL3 gene influences childhood asthma and that the TT genotype of the rs7216389 polymorphism is associated with childhood asthma in the Chinese population.

[CFTR gene variations and phenotypes in seven children].

Objective: To analyze the cystic fibrosis transmembrane conductance regulator (CFTR) gene variations and phenotypes in 7 Chinese children. Methods: In this retrospective study, the data of 7 children with CFTR gene variations admitted to Children's Hospital of Chongqing Medical University from December 2013 to October 2020 were extracted. The general information, clinical manifestations, gene variations, diagnosis and treatment were summarized. Results: Among the 7 children, 2 were males and 5 were females, aged 5.2(0.5-11.3) years. Main clinical manifestations included malnutrition (5 cases), recurrent respiratory infection (4 cases), bronchiectasis (3 cases), steatorrhea (3 cases), vomiting in infancy (2 cases), liver cirrhosis (2 cases), meconium ileus (1 case), metabolic alkalosis and hypochloremia (1 case). A total of 15 variations were found by whole exon sequencing and Sanger sequencing, among which 3 were newly discovered, and 7 were missense mutations. Four children were diagnosed as CF, and the other 3 were diagnosed as CFTR related disease (CFTR-RD). Compared with CF patients, the pancreatic insufficiency and typical CF lung disease were relatively mild in CFTR-RD patients. After treatment, 6 children were clinically improved, while the rest one withdrew treatment due to critical pulmonary infection and disturbance of water-electrolyte metabolism. Conclusions: The loci and phenotypes of CFTR gene variants vary hugely and the pathogenicity of some variations are not clear. Whole exon sequencing can facilitate the identification of CF-and CFTR-RD-causing variaions. For the cases not compatible with CF, CFTR-RD should be considered and evaluated by timely gene detection, so as to carry out appropriate long term management.

[Matching in observational research: from the directed acyclic graph perspective].

Matching is a standard method for selecting research objects regarding the observational research, which controls confounding factors and improves statistical efficiency. However, its role in controlling confounding is not consistent in different observational studies. Matching can eliminate the confounding bias of matching variables in cohort studies, but checking on itself cannot eliminate confounding bias in case-control studies. In matched case-control studies, researchers may not accurately judge whether the variable is a confounder. Sometimes the variables that are not confounders are mistakenly matched. In that case, it will result in overmatching, which will lead to the decline of statistical efficiency or the introduction of unavoidable bias or increase of workload. If the real confounding factors are omitted, it will cause confounding bias. Therefore, researchers should consider what kind of matching variable selection criteria should be formulated. A directed acyclic graph is a visual graphic language that can show the complicated causality among different epidemiological research designs. This article analyzes the role of Matching in different observational research designs from the perspective of the directed acyclic graph, formulates the selection criteria for matching variables in matched case-control studies, and provides some reference suggestions for future epidemiological research design.

[A cohort study on the new infections and natural clearance of anal human papillomavirus types 16 and 18 in men who have sex with men].

Objective: To understand the infection status and elimination of anal human papillomavirus (HPV) among men who have sex with men (MSM) in Urumqi, Xinjiang. Methods: The sample size formula in cohort study, a dynamic cohort study method, was used, with the sample size estimated to be 712 according to the new infection rate of HPV16. With the help from non-government organzitions in Urumqi, we recruited 810 MSMs by the snowballing method, and a follow-up program was carried every six months. Anal exfoliated cells were collected to analyze HPV type 16 and 18 infection rates. For statistical analyses, Poisson regression was used to estimate the density of new infections and persistent infections. Cox proportional hazard model was used to explore the influencing factors on both new and persistent infections and the diseases' natural clearing. Results: A total of 810 MSM were recruited, and 482 MSMs with the number of follow-ups more than 2 times were included in the analysis, with the total follow-up numbers as 994.7 person-years. The median number of follow-up and follow-up times was 4 (P25,P75:3,5) times , and 2.2 (P25,P75:1.8, 2.6) years. The baseline infection rates of HPV16 and HPV18 were 8.5% (41/482) and 3.3% (16/482), respectively. And the baseline mixed infection rate of the two types was 0.6% (3/482). The first new infection densities of HPV16 and HPV18 were 10.06 (95%CI:8.12-12.45)/100 person-years and 5.24 (95%CI:3.95-6.96)/100 person-years. The rate of natural infection clearance of HPV16 and HPV18 were 71.2% (89/125) and 71.8% (46/64), respectively. The natural clearance rate of HPV18 after 1.5 years follow-up was higher than HPV16 (97.7% vs. 94.1%). The persistent infection rate of HPV16 and HPV18 were 4.5% (20/441) and 1.7% (8/466), respectively. The risk of persistent HPV16 infection among unmarried subjects was lower than that of married subjects (aHR=0.29,95%CI:0.12-0.71). The natural clearance rate of HPV18 without condom use in anal intercourse in the last six months was 2.63 times higher than that of condom use (95%CI:1.08-6.42). Conclusions: HPV16 and 18 new infections are more common among MSM in Urumqi, and the natural clearance rate is higher. Compared with HPV18, HPV16 has a higher density of new and persistent infections, a low natural clearance rate, and a greater risk of the diseases.

[Formation of study population for causal inference].

Epidemiological analysis describes and compares the characteristics of a certain number of people to make causal inferences. The formation of the study population is always the first step. In this paper, we first define the concepts of cross-sections at both individual level and population level and introduce the three assumptions needed in the measurements in observational studies, i. e. the true values of the attributes are stable with time, the attribute variables are independent and the individuals are independent during the measuring process. We also determine that the causal inference research should be unified based on the time of the occurrence or beginning of a postulated cause, or exposure, should be in. Then, based on the dual roles of the population cross-section with causal thinking, we propose that research designs can be classified into two types with different characteristics: history reconstruction research and future exploration research. Finally, we briefly analyze the research design framework and the relationship between estimated effects and different designs. The discussion of the formation of a study population from the perspective of causal thinking can make a foundation for the classification of causal inference research design with appropriate effect parameters, which needs to be further studied.

Influence of dopants Ti and Ni on bonding interactions and dehydrogenation properties of lithium alanate.

We report a study of the influence of Ti and Ni dopants on the stability and bonding interactions of LiAlH(4) using the first-principles method. Both the Ti and the Ni prefer to occupy an interstitial site in the LiAlH(4) owing to lower occupation energies estimated from the total energy calculations. Calculations show that the bonding interactions between the Al and the H atoms within the [AlH(4)] groups were significantly reduced by the dopants, and both the stability and the geometry of the [AlH(4)] group were distorted in the doped LiAlH(4) systems. However, Ti and Ni use different mechanisms to improve the dehydrogenation properties of LiAlH(4). The Ti dopant tends to interact with the Al atom in its neighbouring [AlH(4)] to 'free' the H atoms from these [AlH(4)] groups. The effect of Ni dopant on the stability and the bonding interactions of the LiAlH(4) is due to the induction of the Ni d electrons that could cause a bonding interaction between the Ni and the Al atoms, strengthening the interactions between the Li and the H atoms, and 'freeing' the H atoms from the neighbouring [AlH(4)] groups as well.

[May cross-sectional studies provide causal inferences?]

Due to the flaws inherited in synchronicity, statistical association and survivor bias on variables under measurement, a common 'consensus' has been reached on "cross-sectiional studies (CSS) can lead to failure on causal inference". In this paper, under both causal thinking and diagram, the real and measured cross-sections are clearly defined that these two concepts only exist theoretically. In real CSS research, the temporal orders of measured variables are all non-synchronic, equivalent to the assumption that measurement variables are independent to each other, or there is no differentiated classification bias. Similar to cumulative case-control or historical cohort studies, both exposure and outcome that exist or occur before their measurements in cross-sectional studies, are actions of historical reconstruction or doing 'Archaeology'. One of the common preconditions for causal inference in such studies is that: there must be a causal relation between the measured variables and their historical counterparts. The measured variables are all agents of their corresponding real counterparts, and the temporal orders are not that important in causal inference. It is necessary to better understand the analytic role of the CSS.