Investigation of fire protection performance and mechanical properties of thin-ply bio-epoxy composites

Hybrid composites composed of bio-based thin-ply carbon fibre prepreg and flameretardant mats (E20MI) have been produced to investigate the effects of laminate design on their fire protection performance and mechanical properties. These flame-retardant mats rely primarily on expandable graphite, mineral wool and glass fibre to generate a thermal barrier that releases incombustible gasses and protects the underlying material. A flame retardant (FR) mat is incorporated into the carbon fibre bio-based polymeric laminate and the relationship between the fire protection properties and mechanical properties is investigated. Hybrid composite laminates containing FR mats either at the exterior surfaces or embedded 2-plies deep have been tested by the limited oxygen index (LOI), vertical burning test and cone calorimetry. The addition of the surface or embedded E20MI flame retardant mats resulted in an improvement from a base line of 33.1% to 47.5% and 45.8%, respectively. All laminates passed the vertical burning test standard of FAR 25.853. Cone calorimeter data revealed an increase in the time to ignition (TTI) for the hybrid composites containing the FR mat, while the peak of heat release rate (PHRR) and total heat release (TTR) were greatly reduced. Furthermore, the maximum average rate of heat emission (MARHE) values indicated that both composites with flame retardant mats had achieved the requirements of EN 45545-2. However, the tensile strengths of laminates with surface or embedded flame-retardant mats were reduced from 1215.94 MPa to 885.92 MPa and 975.48 MPa, respectively. Similarly, the bending strength was reduced from 836.41 MPa to 767.03 MPa and 811.36 MPa, respectively

Nonexistence of entire positive solution for a conformal kk-Hessian inequality

summary:In this paper, we study the nonexistence of entire positive solution for a conformal $k$-Hessian inequality in $\mathbb {R}^n$ via the method of proof by contradiction

The Role of Oxymatrine in Amelioration of Acute Lung Injury Subjected to Myocardial I/R by Inhibiting Endoplasmic Reticulum Stress in Diabetic Rats

Background. Oxymatrine (OMT) is the primary pharmacological component of Sophora flavescens Aiton., which has been shown to possess potent antifibrotic, antioxidant, and anti-inflammatory activities. The aim of the present study was to clarify the protective mechanism of OMT on acute lung injury (ALI) subjected to myocardial ischemia/reperfusion (I/R). Methods. A myocardial I/R-induced ALI model was achieved in diabetic rats by occluding the left anterior descending coronary artery for 1 h, followed by reperfusion for 1 h. The levels of inflammatory factors (tumor necrosis factor-α, interleukin- (IL-) 6, and IL-17) in bronchoalveolar lavage fluid were assessed using commercially available kits. The index of myocardial injury, including the detection of cardiac troponin I (cTnI), cardiac troponin T (cTnT), lactate dehydrogenase (LDH), and creatine kinase-MB (CK-MB), was also determined using commercially available kits. Hematoxylin and eosin staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to identify histological changes. The expression levels of endoplasmic reticulum chaperone BiP (GRP78), DNA damage-inducible transcript 3 protein (CHOP), eukaryotic translation initiation factor 2-alpha kinase 3 (PERK), inositol dependent enzyme 1α (IRE1α), ATF6, caspase-3, -9, and-12, Bcl-2, and Bax were determined by Western blotting. The mRNA expression levels of GRP78 and CHOP were detected by reverse transcription-quantitative PCR. Results. Myocardial I/R increased the levels of cTnI, cTnT, LDH, and CK-MB in diabetic rats. Damaged and irregularly arranged myocardial cells were also observed, as well as more serious ALI with higher lung injury scores and WET/DRY ratios and lower PaO2. Moreover, the expression of key proteins of endoplasmic reticulum stress (ERS) was increased by I/R injury, including phosphorylated- (p-) PERK, p-IRE1ɑ, and ATF6, as well as decreased levels of apoptosis. These effects were all significantly reversed by OMT treatment. Conclusions. OMT protects against ALI subjected to myocardial I/R by inhibiting ERS in diabetic rats

Effect of silane coupling agent on the properties of recycled carbon fibers reinforced bio-based epoxy composites

In this work, the effect of a silane coupling agent on the mechanical behavior of recycled carbon fiber reinforced bio-based epoxy composites was studied. For this purpose, the surface of the recycled carbon fiber was treated with 3-aminopropyltriethoxysilane (APS) agent at the concentrations in the 0-8 wt.% range. Dynamic mechanical analysis and characterization of the tensile and flexural properties were performed to observe the mechanical behavior of the specimens, and the morphology of the fracture surface after mechanical testing was also studied by scanning electron microscopy. It was found that the glass transition temperature and the tensile and flexural strengths of the composites increased with an addition of a suitable amount of the silane agent (< 4 wt.%), which was attributed to the cross-linking and curing reaction between the amino groups of APS and the epoxy matrix that improved the interfacial bonding. Thus, an appropriate concentration of the silane coupling agent can improve the mechanical properties of recycled carbon fiber reinforced bio-based epoxy composites

Superiority of indocyanine green-enhanced near-infrared fluorescence-guided imaging for laparoscopic lymph node dissection in patients with early-stage endometrial cancer: A retrospective cohort study

Objective: Laparoscopic pelvic lymph node dissection (LPND), which is an effective therapy for endometrial cancer, is challenging because of the complexity of the procedure and the occurrence of postoperative complications. This study aimed to explore whether indocyanine green (ICG)-enhanced near-infrared (NIR) fluorescence-guided LPND is superior to LPND in the context of early-stage endometrial carcinoma. Methods: In this retrospective study, we included the medical records of 190 patients with early-stage endometrioid adenocarcinoma who underwent LPND at the Department of Obstetrics and Gynecology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine between January 2019 and January 2021. Depending on whether ICG-enhanced NIR fluorescence guidance was used, the patients were assigned to the ICG group or non-ICG group. Patients were followed-up for one year after surgery. Data on demographic characteristics, pathological results, operative outcomes, and complications were collected and analyzed. Results: The baseline characteristics were comparable between the ICG group and non-ICG group, including age, BMI, pregnancy history, and preoperative hemoglobin. For surgical outcomes, the patients in ICG group had significantly lower intraoperative blood loss (50 mL vs. 120 mL, p < 0.001), less postoperative pelvic drainage time (4.14 ± 1.44 d vs. 5.70 ± 1.89 d, p = 0.001), shorter duration of hospital stay (5.26 ± 1.41 d vs. 7.37 ± 1.85 d, p = 0.003), higher number of positive pelvic lymph nodes (PLNs) (1 vs. 0, p = 0.003), and more PLN-positive cases (16.0% vs. 3.6%, p = 0.003) than the patients in non-ICG group. However, no significant differences were noted in blood transfusion requirement, operative time, hemoglobin level decreases, number of PLNs harvested, or the presence of lymphocysts between the two groups. Conclusion: Our study showed that ICG-enhanced NIR fluorescence-guided operation may improve the accuracy and safety of LPND

A Periodic Assessment System for Urban Safety and Security Considering Multiple Hazards Based on WebGIS

With the frequent occurrence of various disasters and accidents, realizing the periodic assessment and visualization of urban safety and security considering multiple hazards is of great significance for safe urban development. In this paper, a periodic assessment system is developed for urban safety and security considering multiple hazards, based on WebGIS. This system consists of an assessment module, a visualization module, and an assistant module that integrates the assessment model to process the assessment data quickly and realizes the visualization of a thematic map and data statistics for rationalizing assessment results. The assessment of a typical urban area was carried out to prove that the created system can effectively conduct periodic assessments and support single-hazard and multi-hazard analysis and auxiliary decision-making. This system can be applied to the grid management and periodic assessment of urban areas at different levels, with high expansibility and application value. It can also help to promote the sustainable construction of a safe and smart city

Fie [sic: Fire] performance of sandwich composites with intumescent mat protection: evolving thermal insulation, post-fire performance and rail industry testing

In this study, a novel approach to improving the fire performance of sandwich composites without effect on intrinsic composite structure was explored. The intumescent mat M10 and M20 with expansion ratio 10:1 and 20:1, respectively, were used to protect sandwich composite with evaluation for thermal insulation, heat release rate, smoke density, smoke toxicity, and post-fire performance. Due to char layer formed with expanded graphite when intumescent mat exposed to fire, significant reduction in the maximum average rate of heat emission (MARHE), specific optical density and Valeur Obscurcissement Fumee values in the initial 4 min (VOF4) were observed for sandwich composite with intumescent mat protection, which also improved mechanical properties retention following exposure to flame. According to the EN 45545 standard, all composites passed HL3 hazard level of smoke toxicity. However, due to higher expansion ratio, sandwich composites with M20 mat passed HL3 hazard level of MARHE and HL2 for specific optical density. As such, the M20 mat with excellent flame retardant performance and mechanical properties retention could be potentially used for rail industry applications

Video1_To use a simple hernia needle for single-port laparoscopic percutaneous inguinal hernia repair in children: a 5-year experience study.mp4

PurposeThe aim of this study is to investigate the technique and practical significance of using a simple hernia needle in single-port laparoscopic herniorrhaphy in pediatric patients.MethodsThe study conducted a retrospective analysis of all pediatric patients who underwent treatment for inguinal hernia using single-port laparoscopic herniorrhaphy with a simple hernia needle at Yellow River Sanmenxia Hospital from June 2018 to May 2023. The medical records of all the children were collected, and clinical characteristics, procedural information, and follow-up data were carefully reviewed.ResultsA total of 848 patients underwent inguinal hernia repair, with ages ranging from 7 months to 13 years (2.99 ± 2.49 years), including 756 males and 92 females. A total of 528 cases of unilateral hernia and 310 cases of bilateral hernia were reported, with intra-operative findings revealing contralateral occult hernia in 253 cases. Single-port laparoscopic herniorrhaphy was successfully completed in all patients, with no instances of conversion to open surgery. The mean operation time for unilateral hernia repair was (7.50 ± 4.80) min, while for bilateral hernia repair it was (11.55 ± 7.27) min. Five patients presented with subcutaneous emphysema, while two patients experienced a recurrence of inguinal hernia. No complications, such as scrotal hematoma, trocar umbilical hernia and testicular atrophy, were observed. The duration of the follow-up period ranged from 3 to 24 months.ConclusionThe promotion and utilization of single-port laparoscopy combined with a simple hernia needle in clinical practice are justified. Our initial investigation indicates that this surgical approach is both safe and dependable for the management of pediatric inguinal hernia. The procedure presents numerous benefits, including the utilization of uncomplicated instruments, straightforward operation, a clear curative impact, minimal tissue damage, rapid recovery, and the absence of scarring.</p