Fracture Mode Transition during Assembly of TC4 High-Lock Bolt under Tensile Load: A Combined Experimental Study and Finite Element Analysis

Fracture during the assembly process is an important failure mode for high-lock bolts used in the aviation industry, which greatly increases the potential of unpredictable accidents during service. In the current study, the underlying reasons for fracture during the assembly of a TC4 high-lock bolt was investigated using a tensile test and finite element analysis (FEA). The microstructure of the as-received bolt consisted of a high proportion of α phase, some β phase, and a small amount of α′ phase formed via martensite phase transformation during the rammer process. The experimental force–displacement curves revealed an average yield load of 55.9 kN and a breaking load of 67.65 kN. The corresponding yield strength was calculated to be 0.9 GPa, which was smaller than the standard value of TC4. This was attributed to the preload-induced stress concentration on the thread surface, leading to obvious strain hardening, which can lead to crack initiation. The effect of preload was further confirmed by the fractographies in which the initial crack was observed on the thread surface. The fractographies suggested that hybrid fracture occurred on the tensile loaded bolt. The initial failure was brittle fracture on the thread surface, transforming into ductile fracture in the screw. The results can contribute to understanding the effect of preload on the load carry capacity of high-lock bolts and provide a strategy to design its assembly specification.     

住院老年糖尿病14例跌倒原因及护理对策

跌倒是老年人常见的意外,这种意外在老年糖尿病病人中发生率更高,常引起骨折、头部损伤、腰扭伤等并发症,并直接影响老年病人的生活质量。本文对14例住院老年糖尿病病人的跌倒现象进行分析,以寻找原因及最佳的护理对策。     

Effect of the Surface Morphology of Porous Coatings on Secondary Electron Yield of Metal Surface

Surface roughening is an important material surface treatment technique, and it is particularly useful for use in secondary electron yield (SEY) suppression on metal surfaces. Porous structures produced via roughening on coatings have been confirmed to reduce SEY, but the regulation strategy and the influence of process parameters both remain unclear in the practical fabrication of effective porous structures. In this paper, the effect of the surface morphology of porous coatings on the SEY of aluminum alloy substrates was studied. Surface characterization and SEY measurements were carried out for samples with a specific process technique on their surfaces. An exponential fitting model of the correlation between surface roughness and the peak values of SEY curves, δm, was summarized. Furthermore, an implementation strategy to enable low surface SEY was achieved from the analysis of the effect of process parameters on surface morphology formation. This work will aid our understanding of the effect of the irregular surface morphology of porous coatings on SEY, thereby revealing low-cost access to the realization of an easy-to-scale process that enables low SEY.     

Prevention of Gestational Diabetes Mellitus and Gestational Weight Gain Restriction in Overweight/Obese Pregnant Women: A Systematic Review and Network Meta-Analysis

Background: Overweight/obesity is associated with pregnancy-related disorders, such as gestational diabetes mellitus (GDM) and excessive gestational weight gain (GWG). Although multiple interventions have been proposed to prevent GDM and restrict GWG, our knowledge of their comparative efficacy is limited. Objective: To evaluate the effectiveness and identify the optimal intervention strategy to prevent GDM and restrict GWG among overweight/obese pregnant women. Methods: Randomized controlled trials that recruited overweight/obese pregnant women at <20 gestational week were obtained. Predictive and confidence interval plot and surface under the cumulative ranking (SUCRA) were performed using Stata statistical software to determine and compare the efficacy of interventions (diet, physical activity (PA), diet + PA intervention and medication). Results: 23 studies with a total of 8877 participants were eligible for analysis. Our results indicated that although neither PA, diet + PA, diet nor medication intervention could significantly protect overweight/obese women from the development of GDM, there was a trend that PA and diet + PA intervention were preventive factors of GDM. Of these, PA intervention (SUCRA, 82.8%) ranked as the superior strategy, and diet intervention (SUCRA, 19.7%) was the least efficacious regimen. Furthermore, interventions of diet, PA and diet + PA were significantly beneficial for GWG restriction, whereas medication intervention could not restrict GWG. In detail, diet intervention (SUCRA, 19.7%) ranked as the optimal regimen, whilst PA intervention (SUCRA, 62.3%) ranked as the least efficacious regimen. Conclusion: Although none of the interventions could offer remarkable benefit for GDM prevention, interventions of diet, PA and diet + PA were significant factors to restrict GWG. In aggregate, diet + PA intervention seemed the superior choice for the prevention of both GDM and excessive GWG. Registration: PROSPERO CRD42022313542.     

胰岛素联合罗格列酮或二甲双胍治疗对2型糖尿病患者血清hCRP的影响

目的 了解胰岛素联合罗格列酮或二甲双胍治疗对2型糖尿病患者血清hCRP水平的影响。方法 将符合纳入标准的2型糖尿病患者60例。随机分成A,B两组。A组给予胰岛素联合罗格列酮（4mg／d。n=30）治疗。B组给予胰岛素联合二甲双胍治疗（n=30）,共8周,治疗前后分别测空腹血糖、餐后2h血糖、糖化血红蛋白及血清hCRP等。结果胰岛素联合罗格列酮或二甲双胍治疗。均能降低血糖和糖化血红蛋白（P〈0．05）。治疗前后。罗格列酮组hCRP水平降低了1．8mg／L。二甲双胍组hCRP水平降低了0．9mg/L,但均未达到统计学意义（P〉0．05）。结论 罗格列酮或二甲双胍在胰岛素治疗2型糖尿病患者的基础上。对血清hCRP水平进一步降低作用不明显。     

昆明地区1538例儿童急诊创伤患者流行病学分析

目的 研究昆明市儿童急诊创伤患者流行病学特征,为降低儿童创伤发生率以及合理制定医疗方针提供依据.方法 回顾性分析2019年9月—2020年8月昆明市儿童医院收治的1538例创伤儿童患者的临床资料,从儿童年龄、性别、致伤原因、主要损伤部位及创伤严重程度等方面进行分析,将致伤原因分为跌倒伤、道路交通伤、高处坠落伤、机械锐器...     

Evolution Characterization and Pathogenicity of a Porcine Reproductive and Respiratory Syndrome Virus Isolate from a Pig Farm in Shandong Province,China

In recent years, porcine reproductive and respiratory syndrome virus (PRRSV) strains have been experiencing extensive recombination in Chinese swine farms. This recombination usually happens in NADC30/34 strains and highly pathogenic (HP) PRRSV strains. This study identified a new PRRSV isolate that shared 99% and 99.1% nucleotide identity with CH-1a and CH-1R at the genomic level, respectively. After purification by viral plaque assay, this isolate was named PRRSV CSR1801. The isolate did not experience any recombination with other PRRSV strains common in swine herd epidemics in China, which means it still maintains the stable features of the classical PRRSV strain and did not easily recombine with other PRRSV strains. Further analysis of the pathogenicity of the PRRSV isolate CSR1801 was performed in piglets. The results indicated that none of the inoculated piglets showed the typical clinical manifestations of PRRS, which presented with runny noses, rough back hair, rectal temperatures always below 40.5 °C, and no deaths. Additionally, no obvious histopathological lesions such as severe interstitial pneumonia could be observed in the lungs of the piglets. Hence, the PRRSV isolate CSR1801 should be classified as a classical-like PRRSV strain. This classical PRRSV strain showed genetic stability and maintained low pathogenicity. This study may provide new clues for further understanding the genetic evolution and pathogenicity of PRRSV and may also be an important reference for the prevention and control of PRRS in swine farms.     

Numerical Simulation and Experimental Validation of Squeeze Casting of AlSi9Mg Aluminum Alloy Component with a Large Size

The squeeze casting process for an AlSi9Mg aluminum alloy flywheel housing component was numerically simulated using the ProCAST software, and orthogonal simulation tests were designed according to the L16 (4) ⁵ orthogonal test table to investigate the alloy melt flow rule under four factors and four levels each of the pouring temperature, mold temperature, pressure holding time and specific pressure, as well as the distributions of the temperature fields, stress fields and defects. The results showed that the flywheel housing castings in all 16 test groups were fully filled, and the thinner regions solidified more quickly than the thicker regions. Hot spots were predicted at the mounting ports and the convex platform, which could be relieved by adding a local loading device. Due to the different constraints on the cylinder surface and the lower end surface, the solidification was inconsistent, the equivalent stress at the corner junction was larger, and the castings with longer pressure holding time and lower mold temperature had larger average equivalent stress. Shrinkage cavities were mainly predicted at mounting ports, the cylindrical convex platform, the peripheral overflow groove and the corner junctions, and there was also a small defect region at the edge of the upper end face in some test groups.     

Risk factors for and predictive nomogram of overall survival in adult patients with craniopharyngiomas: A SEER population-based study

Studies with relatively large sample size as well as long-term follow-up focusing on adult craniopharyngioma (CP) patients are still lacking. We attempted to identify independent prognostic factors and establish a nomogram model to estimate survival rates for adult CP patients.The Surveillance, Epidemiology, and End Results database was used to obtain data on patients with CP. Univariable and multivariable Cox analyses were utilized to identify the prognostic factors of adult CP patients. A survival prediction model was constructed and its predictive performance was also assessed.A total of 991 patients (695 in training group and 296 in validation group) were eligible for final inclusion. Multivariate Cox analysis presented that age at diagnosis, marital status, race, tumor size, and surgery type were statistically significant prognostic factors for overall survival (all P < .05). A graphical predicting nomogram model was developed to calculate the predicted patients’ survival probabilities at 1, 2, 5, and 10 years. The concordance indexes were 0.708 ± 0.019 and 0.750 ± 0.025 for the training and validation samples, respectively, demonstrating favorable discrimination abilities. Similarly, the time-dependent area under curve also showed overall satisfactory discrimination ability. Favorable consistencies between the predicted and actual survival were presented according to the calibration curves.An easy-to-use nomogram, being proven to be with reliable discrimination ability and accuracy, was established to help predict overall survival for adult patients with CP using the identified significant prognostic factors.     

Pediatric Acute Severe Hepatitis of Unknown Origin: What is New?

Globally, there are emerging cases of acute severe hepatitis of unknown origin in children. These cases have gathered increasing attention, owing to the development of acute liver failure in some cases that resulted in liver transplantation. This review briefly summarizes the outbreak and diagnostic criteria of the disease. We further discuss the possible causes and related mechanisms underlying its occurrence and progression, and analyze the challenges in management. Finally, this review emphasizes patient management in clinical settings and a combination of efforts to unmask the disease.