Search

Abstract Purpose This study aims to provide a comprehensive overview of anesthesia management strategies employed in pediatric lung transplantation. Methods A retrospective analysis was conducted on data from 14 pediatric patients who underwent lung transplantation at the Wuxi Center between September 2019 and November 2022. Patient demographics, surgical particulars, airway management, utilization of extracorporeal support, fluid administration, blood gas and electrolyte profiles, and postoperative outcomes were systematically documented and subsequently summarized. Results Of the 14 patients, 7 received extracorporeal membrane oxygenation (ECMO) and 1 received cardiopulmonary bypass (CPB). The average operation time was 303 ± 53 min, with the median extubation time of 26 h. The entirety of pediatric lung transplant procedures was executed successfully, resulting in the discharge of thirteen patients postoperatively. Regrettably, one patient died due to infectious shock on the fourth postoperative day. Conclusion The achievement of successful pediatric lung transplantation necessitates effective perioperative anesthesia management, with a focal emphasis on circulatory control. Real-time measurements serve as the cornerstone for decision-making. Proactive administration of vasoactive agents is integral to sustaining hemodynamic stability. The judicious assessment of ECMO necessity is paramount, favoring central ECMO during the surgical intervention.

SOCS (Suppressor of Cytokine Signalling) proteins are intracellular negative regulators that primarily modulate and inhibit cytokine-mediated signal transduction, playing a crucial role in immune homeostasis and related inflammatory diseases. SOCS act as inhibitors by regulating the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, thereby intervening in the pathogenesis of inflammation and autoimmune diseases. Recent studies have also demonstrated their involvement in central immunity and neuroinflammation, showing a dual functionality. However, the specific mechanisms of SOCS in the central nervous system remain unclear. This review thoroughly elucidates the specific mechanisms linking the SOCS-JAK-STAT pathway with the inflammatory manifestations of neurodegenerative diseases. Based on this, it proposes the theory that SOCS proteins can regulate the JAK-STAT pathway and inhibit the occurrence of neuroinflammation. Additionally, this review explores in detail the current therapeutic landscape and potential of targeting SOCS in the brain via the JAK-STAT pathway for neuroinflammation, offering insights into potential targets for the treatment of neurodegenerative diseases.

Abstract Polyether block amide (PEBA) is an important thermoplastic polyester elastomer (TPE) owing to its low density and high resilience. Microcellular foaming can endow PEBA with significant potential in sports, medical, and industrial applications. However, with the current microcellular foaming technology, it remains challenging to obtain PEBA foams with stable shapes, which are critical for their mechanical properties. Therefore, microcellular foaming with CO2 and N2 as co‐blowing agents is utilized in this study to achieve mechanically robust PEBA foams by reducing the dimensional shrinkage. The introduction of N2 can effectively slow the diffusion rate of blowing agents into the air, providing support for the foam to resist external atmospheric pressure and effectively reducing the dimensional shrinkage of PEBA foams. Consequently, a stable foam shape is achieved with an expansion ratio of 7.9. Finally, the PEBA foams with excellent shrinkage resistance and mechanical properties are prepared, and the cell shrinkage mechanism is analyzed to study the effects of blowing agents and foaming methods on the structural evolution of TPE foams. This promising outcome paves way for their practical industrial applications.

Poly (ether-block-amide) PEBA foams have been widely used in many industrial fields. However, compared with amorphous polymers, the microcellular foaming process of PEBA is more complicated due to their complex phase morphology evolution behavior. Moreover, the productivity was limited owing to the long saturation time for thick samples. In this study, we proposed an efficient pre-foamed method to fabricate low density poly(ether-block-amide) foams. PEBA foams with controlled rather high density were firstly prepared by microcellular foaming under relatively low foaming temperatures. Afterwards, the pre-foamed PEBA sample with a high density were further foamed into much lower density by using secondary microcellular foaming under relatively high foaming temperature. The microphase separation phenomenon in PEBA was clearly studied by scanning transmission electron microscopy and atomic force microscopy-based infrared spectroscopy technique. Thanks to pre-foaming process, the diffusion rate of CO2 in PEBA matrix was greatly increased, resulting in shorter saturation time in microcellular foaming process. Most interestingly, pre-foaming process can also help PEBA achieve a higher expansion ratio compared with traditional microcellular foaming process with the same foaming parameters. Pre-foaming driven foaming process was a practical way of achieving low-density PEBA foams efficiently without adding new equipment, especially for thick parts.

Challenges remain in large-scale and successive preparation of porous polymer composite component, which limits its practical applications for high-performance electromagnetic interference (EMI) shielding. Herein, a scalable and efficient method based on mold-opening foam injection molding was developed to fabricate carbon fiber (CF) reinforced polymer composite foams for EMI shielding applications. Thanks to the novel foaming process and heterogeneous nucleation effect of CF, real microcellular poly(ether-block-amide) (PEBA)/CF composite foams with an average cell size of 6.6 μm and a cell density of up to 109 cells/cm3 were achieved. Due to the significantly refined cellular morphology, the PEBA/CF composite foams exhibit superior EMI shielding performance over the unfoamed composites which was characterized by absorption-dominated shielding characteristics and significantly enhanced EMI shielding effectiveness. Furthermore, compared with the unfoamed case, the foamed PEBA/CF composites with refined cellular morphology shows greatly improved cold toughness and duality, and the tensile strain at break and specific tensile toughness are increased by 88.6% and 109.1%, respectively. Moreover, real-microcellular PEBA/CF composite foams have remarkably enhanced surface quality than those fabricated by regular foam injection molding process, and the surface roughness can be maximumly increased by 91.6%. Thus, this study provides a promising strategy for producing lightweight and strong components for high-performance EMI shielding applications.

Due to the ever-increasing consumption of poly (ethylene terephthalate) (PET) for the industries of packaging and electronics, the waste non-degradable PET has brought serious ecological pollution. However, the current recovery rate of waste PET is still limited, and the mechanical and heat-resistant properties are too poor to meet the requirements of practical applications. The recycling of waste PET is of practical significance to material/energy saving and environmental protection, contributing to the sustainable development of economy and society. In this work, an innovative method was proposed to fabricate strong and heat-resistant materials by using waste PET bottle flakes via carbon dioxide (CO2) treatment at ambient temperature. The results show that the crystallinity of the PET samples treated by CO2 at 800 psi is increased by 30.6%, the tensile strength and Young's modulus are increased by 21.9% and 20.6%, respectively, compared with untreated samples. Moreover, the dynamic mechanical analysis indicates that the heat-resistant performance of CO2-treated samples is significantly improved, whose storage modulus increased 33.5% and glass transition temperature increased 17.7 °C. Furthermore, aiming to investigate how the CO2-treatment improved the mechanical performance of the waste PET, the sorption-desorption experiments were conducted to examine the sorption kinetics of CO2 in the matrix, combined with the Avrami model employed to analyze the crystallization kinetics of PET under high-pressure CO2. It demonstrates that the enhancement of the tensile strength is ascribed to the transition of crystals from two-dimensional structures to three-dimensional structures with an increment in the CO2 pressure.

Abstract Flexible microwave absorbers with Joule heating performance are urgently desired to meet the demands of extreme service environments. Herein, a type of flexible composite film is constructed by homogeneously dispersing a hierarchical Ni‐carbon microtube (Ni/CMT) into a processable polytetrafluoroethylene (PTFE) matrix. The Ni/CMT are interconnected into a 3D conductive network, in which the huge interior cavity of the carbon microtube (CMT) improves impedance matching and provides additional hyper channels for electromagnetic (EM) waves dissipation, and the hierarchical magnetic Ni nanoparticles enhance the synergistic interactions between confined heterogeneous interfaces. Such an ingenious structure endows the composites with excellent electrothermal performance and improves their serviceability for application under extreme environments. Moreover, under a low fill loading of 3 wt.%, the Ni/CMT/PTFE (NCP) can achieve excellent low‐frequency microwave absorption (MA) property with a minimum reflection loss of −59.12 dB at 5.92 GHz, which covers almost the entire C‐band. Relying on their brilliant MA property, an EM sensor is designed and achieved by the resonance coupling of the patterned NCP. This work opens up a new way for the design of next‐generation microwave absorbers that meet the requirements of EM packaging, proofing water and removing ice, fire safety, and health monitoring.

Functionally graded polymer foams are advanced materials that exhibit great potential for applications in energy absorption, electromagnetic interference shielding, and high-elasticity due to the graded cellular structure for mechanical performance and functional properties enhancements. However, producing polymer foams with tailored gradient structures remains a significant challenge. Herein, a new microcellular foaming strategy with two-step adsorptions was developed to prepare thermoplastic polyurethane (TPU) foams with gradient cellular structures. The TPU samples were saturated with low-pressure CO2 in the first sorption stage and partially saturated with high-pressure CO2 in the second sorption stage. By regulating CO2 pressure in the first stage and adsorption duration in the second stage, TPU samples with gradient CO2 concentrations were achieved, thereby leading to structure-gradient TPU foams. Finally, a prospective microcellular-macrocellular gradient foam with a cell size range of 30 μm to 400 μm was successfully prepared. The energy loss coefficient of structure-gradient TPU foam can be reduced by 21.5% compared to that of the foam with uniform cellular structure. Structure-gradient TPU foams show significantly enhanced mechanical performance and elasticity, and the underlying mechanism was clarified. The super-elastic TPU foams with tailored gradient structures hold significant promise for broaden applications requiring lightweight, flexibility, and elasticity.

This study provides an insight into the foaming of thermoplastic polyurethane (TPU), which was improved by the crystallization of hard segment domains. This study investigated the effects of packing time in the mold-opening foam injection molding (MOFIM) technology on the crystallization behavior of hard segments in TPU and the cell morphology of TPU foams. It was observed that the prolongation of the packing time, corresponding to a longer crystallization time before foaming, induced an increased crystallinity in the injection-molded TPU solids and foams due to the crystals becoming more close-packed. The enhancement of the foamability of TPU was attributed not only to the increased crystallinity of hard segments, but also to the broader distribution of crystals at the same crystallinity. Furthermore, TPU foams with greater hardness have smaller cell size, higher cell density, and narrower distribution in cell size owing to their higher viscosity and storage modulus than those with lower hardness prepared under the same conditions.

Microcellular polymer foams are a kind of advanced polymeric foams that show light weight and enhanced thermally insulating performance compared with traditional polymer foams. Microcellular injection molding (MIM) has emerged as a pollution-free technique to efficiently prepare microcellular polymer components. However, MIM products surfer from the problems including poor surface appearance, limited weight loss, and deteriorated mechanical properties, which seriously limit the application of this technology. Herein, we reported an approach to fabricate ultra-lightweight, high strength, surface quality and thermal insulation in-situ polytetrafluoroethylene (PTFE) microfibrils reinforced polypropylene (PP) foams using mold opening microcellular injection molding (MOMIM). Firstly, different morphology PP/PTFE composites were prepared by melt blending, and subsequently their crystallization behavior and rheological properties were further investigated. Afterwards, both MIM and MOMIM were conducted to produce PP and PP/PTFE microcellular parts. The results showed that the in-situ fibrillated PTFE benefit to accelerate crystallization, refine crystals and enhance viscoelasticity of PP compared with spherical PTFE. Both fibrillated and spherical PTFE led to greatly refined cellular morphology although the former is more effective. Compared with pristine PP foams, the tensile and impact strength of PP/fibrillated-PTFE foams could be enhanced by 21% and 133%, respectively. Meanwhile, the thermal conductivity of PP/fibrillated-PTFE foams could be reduced by 32% compared with the pristine PP foams. Moreover, MOMIM-fabricated parts exhibited better surface quality compared with MIM-fabricated ones.

Thermoplastic polyurethane (TPU) foams have exhibited promising prospect in many industries such as automobile, sportswear and packaging, due to their outstanding mechanical properties. However, the application of TPU foams prepared by microcellular foaming with CO2 as blowing agents is still limited, due to the serious shrinkage after foaming. Herein, in this study microcellular foaming with mixed CO2 and N2 as co-blowing agents was used to control the shrinking behavior of hexamethylene diisocyanate (HDI)-based TPU foams, and further, the effects of shrinkage, expansion ratio, and cell size on the mechanical properties of TPU foams were decoupled. The results show that the stretching degree of the molecular chain and the solubility of co-blowing agents play a vital role in stabilizing TPU foams. Foams with an expansion ratio of up to 16-fold can be prepared with both pure CO2 and co-blowing agents. The shrinkage ratio of TPU foams prepared with co-blowing agents is 6.3 %, while that of foams prepared with pure CO2 is 37.8 %. Moreover, it is also found that the mechanical properties of TPU foams with a smaller shrinkage ratio are much higher than those with a larger initial expansion ratio and a similar final expansion ratio.

Thermal insulation is vital for achieving efficient thermal management, energy conservation, and emission reduction. However, the existing polymer foams still have some performance limitations and cannot meet the application demands in a wider range of situations. Accordingly, herein, an innovative strategy based on polyvinylidene fluoride (PVDF) melt blending and CO2 microcellular foaming was proposed for the fabrication of lightweight high-performance polymethylmethacrylate (PMMA) foams for heat insulation, and ultralight, tough, and hydrophobic foams with outstanding heat insulation and shape memory performances were successfully prepared. Because of the plasticization of PVDF and nucleation of PVDF microcrystals, the foaming temperature window of PMMA substantially descended, and the cellular structure of PMMA became refined. Blend foams with expansion ratios of 36.2, cell sizes of 15.8 μm, and foam densities of 0.0357 g∙cm−3 were obtained at 130 °C. Due to higher porosity and strong infrared absorption ability of PMMA, the resulting foams exhibited thermal conductivities of less than 32 mW∙m−1∙K−1. Owing to the hydrophobicity and incombustibility of PVDF and its microcrystals, the blend foams demonstrated better hydrophobicities, shape memory properties, and flame retardancies. This study provides an effective way for the green and mass production of high-performance polymer foams with appropriate thermal insulation performances.

Background: Perioperative management involving anesthesiologists plays an important role in prognosis of recipients after lung transplantation. Since the development of lung transplantation, the demand for specialized anesthesiologists continues to increase. As the largest lung transplant center in China, the Wuxi People's Hospital was tasked with trainee anesthesiologists throughout the country in lung transplantation anesthesia. This study aimed to evaluate the current status and training needs of anesthesiologists for the anesthetic management of lung transplantation in Wuxi People's Hospital between 2015 to 2020. Methods: Overall, 53 trainee anesthesiologists for lung transplantation from 35 hospitals were investigated anonymously in our survey. The questionnaire included the anesthesiologists' demographic information, level of satisfaction, training needs and current status in their hospitals. We divided the doctors into two groups depending on the trainee anesthesiologists’ seniority and professional title: intermediate and senior. Survey data were compared between the groups. Results: Significantly more doctors in senior-level positions had clinical research experience than did doctors in intermediate-level positions (P = 0.041). All doctors were highly or very highly satisfied with the training received. Doctors in intermediate-level positions preferred training periods of 4–6 months, while those in senior-level positions preferred 1–3 months of training (P = 0.044). Most doctors considered theoretical courses to be lacking (69.0%), followed by a lack of scenario simulation teaching (54.8%). The most desirable programs were transesophageal echocardiography (TEE, 71.4%) and extracorporeal membrane oxygenation (ECMO, 64.3%). ECMO technology was available in the hospitals of 95.2% of respondents; however, only 2.4% of doctors said the anesthesiology department took charge of perioperative ECMO. Significantly more senior-level doctors chose calibrated pulse contour analysis (P = 0.018) and significantly more intermediate-level ones chose TEE (P = 0.049). Disappointingly, 21.4% doctors reported a lack of certification evaluation for trainee anesthesiologists at their hospitals. Conclusions: Different training programs should be set up according to the trainee anesthesiologists’ level of seniority and training needs. Theoretical courses and scenario simulation training must be added to improve the training program. Moreover, the training of TEE and ECMO requires greater attention. Finally, a standardized completion assessment is required for trainee anesthesiologists.

Sufentanil, a potent opioid, serves as the first option for perioperative analgesia owing to its analgesic effect, long duration and stable hemodynamics, whereas its side effects frequently blunt its application. The intravenous (IV) injection of sufentanil during anesthesia induction has high incidence of choking or bucking reaction, which is defined as sufentanil-induced cough (SIC). Moreover, postoperative nausea and vomiting (PONV) is a common and stressful complication, which is also related to the usage of opioid. High incidence of PONV is reported in the patients with SIC. Hence, we sought to determine whether naloxone, an opioid antagonist, at low dose would decrease the incidences of SIC and PONV. 216 female patients undergoing gynecological laparoscopic operation (

Microcellular injection molding (MIM) is a flexible, efficient, and environmentally friendly foaming technology to prepare plastic foams with complex shapes. However, MIM product suffers from deteriorated mechanical properties, limited weight reduction, and poor surface appearance. In this study, mold-opening microcellular injection molding (MOMIM) was used to prepare high-performance polypropylene/glass fiber (PP/GF) composite foams. GF was used to improve the foaming behavior of PP and to enhance the mechanical properties of foamed samples. Firstly, the crystallization and rheological behavior of PP and PP/GF were analyzed. Afterwards, the foaming behavior of PP and PP/GF in microcellular injection molding process were investigated. Finally, the mechanical properties of PP and PP/GF foams were measured and discussed. It was found that PP/GF composite foams show a rather uniform cellular structure than the pure PP foams. Moreover, PP/GF composite foams exhibit much higher strength and stiffness than the pure PP foams. Furthermore, MOMIM can significantly enhance the flexural modulus of the molded samples. For the foams with an expansion ratio of 1.5-fold, by adding 20 wt% GF, the tensile strength and modulus can be increased by 60% and 50%, respectively. For the PP/GF composite with 20 wt% GF, the foamed sample prepared by MOMIM can have a flexural modulus nearly 200% higher than that of the unfoamed sample. Thus, MOMIM PP/GF composites show a promising perspective in providing lightweight and strong plastic products that can be widely used in automotive, electronics, and appliances.

Thermally insulating polymer foams are instrumental in conserving energy and reducing peak carbon dioxide emissions owing to their light weight, environmental friendliness, and ease of processing. However, as most polymers are organic and flammable, the fire hazards associated with commonly used polymer foams are significant. Accordingly, intrinsic flame-retardant poly(vinylidene fluoride) (PVDF) is considered ideal for fabricating thermally insulating materials. In this study, lightweight, thermally insulating, flame-retardant, and strong PVDF foams were prepared using microcellular foaming. To analyze the crystallization behavior, various saturation pressures and temperatures were applied to investigate their effects on the foaming behavior of PVDF. PVDF foams with expansion ratios of 5–28.8 and cell sizes of 10–250 μm were prepared using microcellular foaming. Moreover, the crystal forms, thermal insulation, flame retardancy, and compressive performance of the structure-tailored PVDF foams were investigated. The foaming process induces the generation of β-phase crystals, and the PVDF foams exhibit excellent thermal insulating (thermal conductivity of 33 mW⋅m−1⋅K−1), flame-retardant, and compressive properties. High-performance PVDF foams can be potentially used for producing advanced flame-retardant thermally insulating materials via green and cost-efficient microcellular foaming.

In-situ polypropylene/polytetrafluoroethylene (PP/PTFE) composites are amazing and promising materials because continuous PTFE fibrils can be dispersed in polymer matrix randomly and uniformly, and meanwhile, PTFE microfibrils can greatly enhance the melt strength and thereby foaming ability of PP. It's worth noting that the crystallization, double influenced by fibrils and carbon dioxide (CO2) environment, plays a very important role in determining the mechanical performance of the composites. In this study, the crystallization kinetics of in-situ PTFE microfibril reinforced PP composites, spherical PTFE particle reinforced PP composites and pristine PP were compared. Furthermore, the crystallization behavior of composites under high-pressure CO2 environment and its influence on the mechanical properties of the material were studied. The crystallization kinetics calculation showed PTFE fibrils have more pronounced heterogeneous nucleation effect than PTFE particles, and yet PTFE fibrils restrict the growth of crystals compared with PTFE particles under atmosphere. Visual observations of crystallization further confirmed that PTFE fibrils led to nucleation-dominated crystallization behavior of PP/PTFE microfibril reinforced composites (MFC) especially under CO2 environment. The refined crystals by PTFE fibrils and further enhanced crystallization by CO2 treatment contributed to remarkably enhanced strength and modulus of PP/PTFE microfibril reinforced composites.

Microcellular injection-molded part can save materials usage and reduce energy consumption. However, the part molded by conventional microcellular injection molding often encounters problems of a limited weight-reduction and poor surface quality. Focusing on these problems, this paper adopted mold-opening microcellular injection molding and talc as nucleating agent to prepare foamed polypropylene (PP) part. Different PP/talc composites were obtained by twin-screw extruder compounding, and their crystallization and rheological behaviors were investigated. The results show that talc can significantly promote PP crystallization, and the crystallization temperature changes slightly with talc content. However, the viscoelasticity of PP melt cannot be enhanced by the added talc. Then, the effects of packing time, mold-opening distance and talc content on the foaming behavior of PP were studied. It is found that a high packing pressure for long time can effectively eliminate the cells generated in melt filling process, thus a transparent part is obtained. With increasing packing time, the unfoamed skin layer of the part increases and cell size decreases. With increasing mold-opening distance, cell density increases. At a same mold-opening distance, cell density remarkably increases because of the heterogeneous nucleation of talc, thus cell size decreases. When talc content is 10 wt.% and weight-reduction of the part is 62.1%, the average cell size is 56.5 μm and the cell density reaches 1.54 × 107 cells/cm3. Because the high packing pressure is employed in the mold-opening microcellular injection molding, the surface quality of the part is improved.

Abstract Background Hypothermic ischemia-reperfusion arrhythmia remains the main factor affecting cardiac resuscitation under cardiopulmonary bypass. Existing research shows that certain miRNAs exhibit significantly different expressions and effects in arrhythmias, however, the effect of miRNAs on the progression of hypothermic ischemic–reperfusion arrhythmias (RA) and its potential mechanism remain to be further explored. Methods Sprague-Dawley (SD) rats were randomly divided into two groups (n = 8): a normal control group (Group C) and a hypothermic ischemia-reperfusion group (Group IR), which were used to establish a Langendorff isolated cardiac perfusion model. According to the arrhythmia scoring system, rats in group IR were divided into a high-risk group (IR-H) and a low-risk group (IR-L). miRNAs expression profiles of ventricular myocardium with global hypothermic ischemia–reperfusion and those of ventricular myocardium with hypothermic ischemia–RA were established through high-throughput sequencing. Furthermore, the aberrantly expressed miRNAs in myocardium with and without hypothermic ischemia–RA were screened and verified. The target genes of these aberrantly expressed miRNAs were predicted using RNAhybrid and MiRanda software. Based on Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, we determined the mRNA targets associated with these miRNAs and studied the miRNA–mRNA interaction during the cardiovascular disease progression. The aberrantly expressed miRNAs related to hypothermic ischemia–RA were validated by Real-time Quantitative polymerase chain reaction (RT-qPCR). Results Eight significantly aberrantly expressed miRNAs (rno-miR-122-5p, rno-miR-429, novel_miR-1, novel_miR-16, novel_miR-17, novel_miR-19, novel_miR-30, and novel_miR-43) were identified, among which six were up-regulated and two were down-regulated. Moreover, target genes and signaling pathways associated with these aberrantly expressed miRNAs were predicted and analyzed. The miRNA–mRNA interaction network graph showed that GJA1 gene was considered as the target of novel_miR-17. Conclusions Aberrantly expressed miRNAs were possibly associated with the formation mechanism of hypothermic ischemia–RA. Specific miRNAs, such as novel_miR-17 and rno-miR-429 are probably new potential targets for further functional studies of hypothermic ischemia–RA.

With the ever-increasing demand for plastic structural components, the development of lightweight plastics is critical for environmental protection and reduced material consumption. Foam injection molding exhibits promise for manufacturing lightweight products, and hence, could be explored for the fabrication of foamed polypropylene (PP) parts. However, it is challenging to fabricate high-performance foam-injection-molded polypropylene (FIM-PP) foams due to the low melt strength of PP. Herein, we have proposed a novel method to prepare lightweight and strong ternary-blended PP foams with enhanced flame retardancy by incorporating in situ-fibrillated polytetrafluoroethylene (PTFE) and talc. The PTFE nanofibrils and talc effectively improved the melt viscoelasticity and crystallization of PP; hence, both, regular and mold-opening foam-injection-molded (MOFIM) ternary-blended PP foams, exhibited refined cellular structures. Furthermore, the MOFIM-PP/Talc/PTFE foam exhibited remarkable mechanical performance, including a 341% increase in the tensile toughness, 408% increase in the notched impact strength, and 121% increase in the flexural strength, which were attributed to the enhanced brittle-to-plastic transition by PTFE nanofibrils and the refined cellular structure. These advantages, combined with the enhanced flame retardancy of the MOFIM-PP/Talc/PTFE foam, make this method cost-efficient, scalable, and green to manufacture lightweight and strong PP foams, thereby broadening the application scope of PP in structural components.

It is a challenge to design Ti3C2Tx MXene-based electromagnetic interference (EMI) shielding composites with excellent mechanical properties. Herein, a highly robust, flexible and durable Ti3C2Tx MXene/carbon fiber fabric/thermoplastic polyurethanes (Ti3C2Tx MXene/CFf/TPU) composite was fabricated through simple electrohydrodynamic atomization deposition, layer-by-layer stacking and hot pressing technology. The synergistic strengthening effect of van der Waals forces and covalent bonds can improve the tensile strength of the composite up to170.2 MPa, which is far greater than that of other MXene-based composites previously reported. In addition, the EMI shielding performance of the Ti3C2Tx MXene/CFf/TPU composite also improved with increasing MXene mass fraction, reaching 40.4 dB, which can be attributed to the dielectric loss provided by conductive fillers and the enhanced absorption within the sandwich structure. More interestingly, the composite retained excellent resistance stability, EMI-SE stability and flexibility, even after multiple bending and releasing cycles. This work provides a facile and environmentally-friendly method for preparing composites with excellent EMI shielding properties and mechanical properties, which may provide more possibilities for applications in intelligent wear and electronic wireless communication equipment.

In-situ fibrillary PTFE was usually developed by melt blending to enhance the melt strength and processability of PP. However, the fibrosis mechanism and the morphology evolution of PTFE during in-situ fibrillation process is still unclear. In this study, both in-situ PP/fibril-PTFE and PP/spherical-PTFE composites were prepared by one-step extrusion process. DSC, XRD, SEM, AFM, as well as O-PTIR analysis were conducted to elucidate the fibrosis mechanism of PTFE. The main reason for the in-situ fibrillation of PTFE-3800 could be ascribed to the chain-extended crystal structure. Furthermore, the acrylate layer of PTFE-3800 can also help PTFE to develop into fibrils. Shear rate was the key parameter in affecting the morphology evolution of PTFE, while processing time could also affect the morphology of PTFE to a certain extent. Interestingly, the SEM analysis showed that reticular crystals are generated in the presence of PTFE fibrils, while spherulites were generated in the presence of PTFE particles. Simultaneous enhancements in the strength, modulus and rigidity were achieved for in-situ fibrillary PTFE reinforced PP composites.

Tough, flexible, and conductive polymer composites show numerous advantages over conventional metal-based materials for EMI shielding applications, for example, in enclosures and packages of electronic devices, due to their low density, high flexibility, excellent corrosion resistance, and easy processing. Herein, thermoplastic polyurethane (TPU) was compounded with flake-shaped nanographite to prepare flexible polymer composite membranes with enhanced mechanical and EMI shielding properties. To regulate TPU/graphite composite's properties, microcellular foaming with carbon dioxide was used to prepare microcellular TPU/graphite composite membranes. Nanographite can significantly promote cell nucleation and hence lead to a refined cellular structure. With 20 wt% nanographite, cell density can be increased by two orders of magnitude. By adding the optimal amount of nanographite, the tensile strength and modulus can be increased up to 28% and 39%, compared to TPU. Although microcellular foaming compromises the tensile properties of the composites, it can significantly enhance their elasticity with more than a 20% decrease in hysteresis loss in comparison to solid ones. Moreover, it is also found that TPU composites with high graphite contents significantly enhanced EMI shielding properties, and microcellular foaming leads to relatively worse EMI shielding performance. Both solid and foamed TPU/graphite composites show promising prospects in EMI shielding applications.

Although polypropylene (PP) foams fabricated by microcellular injection molding (MIM) have been widely studied and globally applied, it is still a big challenge to achieve lightweight products with high mechanical performance. Herein, the MIM method assisted by a fast cooling design was applied to prepare lightweight bimodal nanoporous PP foams with high toughness. A specific mold with a thin cavity was designed to achieve rapid cooling rate during MIM process, and to further accelerate crystallization and refine crystals, which was verified by visualization results, DSC curves, and WAXD patterns. Thus, nanocellular PP foams were prepared, whose high toughness was presented in tensile testing, especially for bimodal cellular foams, more than 327% higher than that of microcellular foams, and up to 53% higher than that of solid. It is owing to the introduced matrix craze, shear yielding, and larger plastic zone by nanocells and the transformed crack propagation direction by microcells. Therefore, this novel toughening method paves a promising prospect for MIM technology to achieve lightweight and tough products for industrial applications.

Due to special micro-nano scale heat transfer effect and the ultra-large specific area, nanocellular polymer foams (NPFs), especially NPFs with high porosity, have great application potential in the fields of heat insulation, filtration, and catalysis. However, since the thermodynamic instability of nanoscale bubbles causes lower nucleation density and cells rupture, developing a green and cost-effective method for fabricating high porosity NPFs remains a challenge. Hence, we proposed a novel method for fabricating high porosity NPFs based the design of materials system and foaming process, and the NPFs with a porosity of over 70%, an average cell size of 287 nm, and a nucleation density of over 1014/cm3 were obtained. Firstly, based on the excellent compatibility between poly (methyl methacrylate) (PMMA) and poly (vinylidene fluoride) (PVDF), homogeneous PMMA/PVDF blends were prepared by melt compounding. Then, the PMMA/(PVDF-microcrystals) system was formed by self-assembly through CO2 induced crystallization. Thanks to numerous homo-dispersed PVDF crystallites' facilitating heterogeneous nucleation and enhancing polymer strength, high porosity NPFs with tailored cellular structures were fabricated by heating foaming. This method provides a simple, flexible, and environmentally friendly way for the preparation of high porosity NPFs.

Abstract Lightweight plastic foams are of great significance for saving resources and reducing energy consumption. Foam injection molding (FIM) shows a promising future to provide lightweight and shape‐complex plastic components. However, it is still challenging to produce lightweight and strong polypropylene (PP) foams by FIM due to PP's poor foaming ability. Herein, rubber and talc are employed to improve PP's foaming ability, and hence to enhance PP foam's mechanical properties. Due to the significantly enhanced rheological properties, injection molded PP composite foam exhibits greatly refined and homogenized cellular structure compared with pure PP foam. Thanks to rubber toughening effect and improved cellular morphology, PP/rubber foam shows much higher ductility than pure PP foam. Moreover, talc particles lead to remarkably enhanced rigidity of PP/rubber foams. Thus, lightweight and strong PP/rubber/talc composite foam is achieved with tensile toughness increased by 82.58% and impact strength increased by 106.21%, and they show broad industrial application prospects.

Objective. To investigate the effect of sevoflurane on the monophasic action potentials (MAPs) in isolated rat hearts after ischemia-reperfusion. Methods. Twenty-four healthy SD male rats, weighing 280–320 g, were randomly divided into three groups after successful preparation of a Langendorff isolated heart perfusion model with a stabilization period perfusion of 15 min with Krebs–Henseleit (K–H) fluid (n = 8): the control group (group A, continuously perfused with K–H fluid for 105 min), the ischemia-reperfusion group (group B, continuously perfused with K–H fluid for 15 min, and then exposed to 60 min of global ischemia induced by Thomas solution followed by 30 min of reperfusion), and the sevoflurane group (group C, K–H fluid contained 1.0 MAC sevoflurane, and other procedures were same as in group B). Heart rate (HR) and MAPs including time course (MAPD50 or MAPD90) of the epicardium (Epi) and endocardium (Endo) were recorded at the time of balance perfusion for 15 min (T0), continuous perfusion for 15 min (T1), reperfusion for 15 min/continuous perfusion for 105 min (T2), and reperfusion for 30 min/continuous perfusion for 120 min (T3), and the transmural dispersion of repolarization (TDR) was calculated. The incidence of arrhythmia, time for restoration of spontaneous heart beat, and duration of arrhythmia were recorded during the period of reperfusion. Results. HR in group B and group C was lower at T2 and T3 than that in group A, while that in group B was significantly lower than that in group A at T2 and T3, and HR in group C was higher than that in group B at T2 and T3 (P0.05), while TDR in group B was increased at T2 and T3 compared with that in group C and group A (P0.05). The time for restoration of spontaneous heart beat and duration of arrhythmia in group C were shorter than those in group B (P0.05). The MAPD90 in group B was much longer than that in other groups at T2 and T3 (P0.05). The prolonged MAPD90 at T2 and T3 in group B strikingly differed from that at T0 and T1 (P0.05). Conclusion. Sevoflurane alleviates reperfusion arrhythmia induced by myocardial ischemia-reperfusion through the shortening of MPAD90 in isolated rat hearts.

The objective of the present study is to investigate the effect of energy-input on the mechanical properties of a 304 stainless-steel joint welded by continuous-drive rotary friction-welding (RFW). RFW experiments were conducted over a wide range of welding parameters (welding pressure: 25⁻200 MPa, rotation speed: 500⁻2300 rpm, welding time: 4⁻20 s, and forging pressure: 100⁻200 MPa). The results show that the energy-input has a significant effect on the tensile strength of RFW joints. With the increase of energy-input, the tensile strength rapidly increases until reaching the maximum value and then slightly decreases. An empirical model for energy-input was established based on RFW experiments that cover a wide range of welding parameters. The accuracy of the model was verified by extra RFW experiments. In addition, the model for optimal energy-input of different forging pressures was obtained. To verify the accuracy of the model, the optimal energy-input of a 170 MPa forging pressure was calculated. Three RFW experiments in which energy-input was equal to the calculated value were made. The joints’ tensile strength coefficients were 90%, 93%, and 96% respectively, which proved that the model is accurate.

The lipase2 from Yarrowia lipolytica (YLLip2) is a yeast lipase exhibiting high homologous to filamentous fungal lipase family. Though its crystal structure has been resolved, its structure-function relationship has rarely been reported. By contrast, there are two amino acid residues (V94 and I100) with significant difference in the substrate binding pocket of YLLip2; they were subjected to site-directed mutagenesis (SDM) to introduce aromatic amino acid mutations. Two mutants (V94W and I100F) were created. The enzymatic properties of the mutant lipases were detected and compared with the wild-type. The activities of mutant enzymes dropped to some extent towards p-nitrophenyl palmitate (pNPC16) and their optimum temperature was 35°C, which was 5°C lower than that of the wild-type. However, the thermostability of I100F increased 22.44% after incubation for 1 h at 40°C and its optimum substrate shifted from p-nitrophenyl laurate (pNPC12) to p-nitrophenyl caprate (pNPC10). The above results demonstrated that the two substituted amino acid residuals have close relationship with such enzymatic properties as thermostability and substrate selectivity.