Numerical Simulation and Process Optimization on Hot Twist-Stretch Straightening of Ti-6Al-4V Alloy Profile

Ti-6Al-4V profiles prepared by hot extrusion are usually accompanied by bending and twisting. The hot twist-stretch straightening is an effective strategy such that the bending deflection and twisting angle can be simultaneously decreased by a single straightening process. In addition, utilizing stress relaxation effect, the residual stress and springback can be greatly reduced by holding the straightening temperature and strain constant for a period after twist-stretch straightening. In this study, the hot deformation behaviors of the Ti-6Al-4V profile were revealed by experiments. The tensile model was obtained by uniaxial tensile tests within ranges of temperatures (500–700 °C) and strain rates (5 × 10⁻⁵–1 × 10⁻³ s⁻¹). The creep constitutive model was acquired with stress relaxation experiments in ranges of temperatures (500–700 °C) and pre-strain of 1.5%. Then, the coupled thermo-mechanical model of hot twist-stretch straightening was established. Based on orthogonal experiment strategy, the effects of straightening temperature, stretch strain, and holding time on the bending deflection and torsion angle of profile were investigated systematically and the process was optimized. The straightening accuracy is significantly affected by straightening temperature and holding time. By using optimized process parameters in practical straightening experiments, the deflection/length and angle/length after straightening does not exceed 2‰ and 2.5‰°/mm, respectively, which is basically consistent with the numerical simulation result.     

Effect of H2S Corrosion on the Fracture Toughness of the X80 Pipeline Steel Welded Joint

To analyze the causes and mechanisms affecting the fracture toughness of X80 pipeline steel welded joints against H₂S, the fracture toughness of different zones of X80 pipeline steel welded joints in both air and saturated H₂S solution was investigated. The fracture toughness of welded joints degraded significantly in the saturated H₂S solution, where the crack tip opening displacement (CTOD) characteristic value in the coarse grain heat-affected zone (CGHAZ) and weld metal (WM) was only 8% and 12% of that in air, respectively. However, the sub-critical grain heat-affected zone (SCHAZ) showed better resistance to H₂S corrosion, with the CTOD characteristic value reaching 42% of that in air. The resistance of the welded joint to H₂S corrosion was sensitive to microstructures. The grain boundary ferrite (GBF) presented in WM, and the angle of grain boundary orientation in CGHAZ was not conducive to hindering crack propagation. Moreover, the formation of the resultant hydrogen cracks owing to the H₂S corrosion also reduced the fracture toughness of the welded joint.     

Marginal bone level change during sequential loading periods of partial edentulous rehabilitation using immediately loaded self-tapping implants: a 6.5-year retrospective study

PURPOSEA large number of studies have suggested the practicability and predictability of immediate implant function, but few studies have reported marginal bone level changes during sequential loading periods. The purpose of this study was to evaluate the marginal bone remodeling of immediately loaded self-tapping implants both at each time point and during each loading period between two time points.MATERIALS AND METHODSThe patients included in this retrospective study were treated with immediately loaded NobelSpeedy Replace implants between August 2008 and July 2009. Differences in the marginal bone level (MBL) at each time point and the marginal bone level change (ΔMBL) between two time points were analyzed with Bonferroni correction (P < .05).RESULTSOverall, 24 patients (mean age, 47.3 ± 12.8 years) with 42 immediately loaded implants and a median follow-up of 6.5 years (IQR, 67.8 months) were included. The cumulative survival rate after 10 - 12 years was 95.2%. Continuous but slow marginal bone loss was observed during long-term follow-up. MBL at both 7.5 years and 11 years was significantly lower than that at loading, 6 months, 2 years and 4 years (P < .05). No bone loss difference was found in any period before 4 years of follow up (P > .05). The loading period of 4 years to 7.5 years showed the largest ΔMBL compared to those of other time periods (P < .05).CONCLUSIONSlight bone loss occurred continuously, and more radical changes of marginal bone can be observed during the period of 4-7.5 years. Thus, long-term effective follow-up of immediately loaded implants is needed.     

The effectiveness of Salvianolate injection for in-stent restenosis after percutaneous coronary intervention: A protocol for systematic review and meta-analysis

Background:In-stent restenosis (ISR) caused by vascular remodeling after percutaneous coronary intervention limits the long-term efficacy of this method. Salvianolate injection is now widely used in the clinical treatment of ISR. However, there is no systematic review or meta-analysis to evaluate the effects of Salvianolate injection on ISR.Methods:We will search articles in 8 electronic databases, including the Cochrane Central Register of Controlled Trials, PubMed, Embase, the Web of Science, China National Knowledge Infrastructure, the Chinese Biomedical Literature Database, Wanfang Database, and the Chinese Scientific Journal Database for randomized controlled trials of ISR treated by Salvianolate injection from their inception to February 27, 2022. The primary outcome measure will be the restenosis rate. The data meeting the inclusion criteria were analyzed by RevMan V.5.4 software. Two authors evaluated the study using the Cochrane collaborative risk bias tool. We will use a scoring method to assess the overall evidence supporting the main results.Results:This study will analyze the clinical effectiveness of Salvianolate injection in the treatment of ISR.Conclusion:The findings of this systematic review will provide evidence to evaluate the effectiveness of Salvianolate injection for the treatment of ISR.INPLASY registration number:INPLASY202220117.     

Clinical application of metagenomic next‐generation sequencing technology in the diagnosis and treatment of pulmonary infection pathogens: A prospective single‐center study of 138 patients

IntroductionRapid and accurate pathogen identification is essential for the treatment of pneumonia. Metagenomic next‐generation sequencing (mNGS) is a newly developed technology to obtain microbial nucleic acid sequence information quickly, efficiently, and without bias.MethodsWe performed shotgun metagenomic next‐generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) for pathogen identification in pneumonia in a prospective study with 138 patients from a single center. We compared the results of mNGS with standard methods including culture, staining, and targeted PCR and evaluated the clinical applicability of mNGS.ResultsMost of the patients (128/138, 92.75%) were cured or improved. One patient (1/138, 0.72%) died because of acute gastrointestinal bleeding, and 9 patients (9/138, 6.52%) showed no improvement. mNGS identified more bacteria (53 versus 27), fewer fungi (8 versus 31), and more viruses (16 versus 1) than standard methods. In total, treatment in 34 out of 138 cases (24.64%) was adjusted and optimized because of mNGS results. Positive mNGS results contributed to a definitive diagnosis in 23 cases (16.67%), which helped guide treatment decision by either adjusting the antibiotics without de‐escalation or continuing the empirical treatment. mNGS also confirmed no active infection in 11 cases (7.97%) allowed for antibiotic de‐escalation.ConclusionThis prospective clinical study evaluated the clinical utility of mNGS for the diagnosis of pneumonia and showed that mNGS of BALF provides valuable information for effective treatment.     

正常中国汉人红细胞中儿茶酚氧位甲基转移酶的活性测定

目的测定正常中国人群红细胞儿茶酚氧位甲基转移酶(COMT)活性浓度值,为研究COMT活性变化在疾病诊断中的应用提供依据。方法采用高效液相色谱法测定279名正常健康人(其中男性134例,女性145例)红细胞中COMT的活性浓度,用SPSS统计软件对性别间测定结果进行检验比较。结果男性和女性红细胞中COMT活性浓度分别为:(16.5±7.4)、(15.5±5.3)nmol.mL RBC-1.h-1。活性频率分布男性在6.0~37.4nmol.mL RBC-1.h-1,女性为5.4~37.2 nmol.mL RBC-1.h-1,男女之间COMT活性浓度的差异无统计学意义(P>0.05)。结论本法灵敏,简便,准确,重复性好,且测定结果与国外一些报道一致,适用于临床应用测定研究。本结果可作为中国健康人红细胞COMT活性正常值及今后研究的重要参考数据。     

Cell-penetrating peptide-doxorubicin conjugate loaded NGR-modified nanobubbles for ultrasound triggered drug delivery

A new drug-targeting system for CD13⁺ tumors has been developed, based on ultrasound-sensitive nanobubbles (NBs) and cell-permeable peptides (CPPs). Here, the CPP-doxorubicin conjugate (CPP-DOX) was entrapped in the asparagine–glycine–arginine (NGR) peptide modified NB (CPP-DOX/NGR-NB) and the penetration of CPP-DOX was temporally masked; local ultrasound stimulation could trigger the CPP-DOX release from NB and activate its penetration. The CPP-DOX/NGR-NBs had particle sizes of about 200?nm and drug entrapment efficiency larger than 90%. In vitro release results showed that over 85% of the encapsulated DOX or CPP-DOX would release from NBs in the presence of ultrasound, while less than 1.5% of that (30?min) without ultrasound. Cell experiments showed the higher cellular CPP-DOX uptake of CPP-DOX/NGR-NB among the various NB formulations in Human fibrosarcoma cells (HT-1080, CD13⁺). The CPP-DOX/NGR-NB with ultrasound treatment exhibited an increased cytotoxic activity than the one without ultrasound. In nude mice xenograft of HT-1080 cells, CPP-DOX/NGR-NB with ultrasound showed a higher tumor inhibition effect (3.1% of T/C%, day 24), longer median survival time (50 days) and excellent body safety compared with the normal DOX injection group. These results indicate that the constructed vesicle would be a promising drug delivery system for specific cancer treatment.