Rubber Toughened and Nanoparticle Reinforced Epoxy Composites

Epoxy resins have achieved acceptance as adhesives, coatings, and potting compounds, but their main application is as matrix to produce reinforced composites. However, their usefulness in this field still limited due to their brittle nature. Some studies have been done to increase the toughness of epoxy composites, of which the most successful one is the modification of the polymer matrix with a second toughening phase. Resin Transfer Molding (RTM) is one of the most important technologies to manufacture fiber reinforced composites. In the last decade it has experimented new impulse, due to its favorable application to produce large surface composites with good technical properties and at relative low cost. This research work focuses on the development of novel modified epoxy matrices, with enhanced mechanical and thermal properties, suitable to be processed by resin transfer molding technology, to manufacture Glass Fiber Reinforced Composites (GFRC’s) with improved performance in comparison to the commercially available ones. In the first stage of the project, a neat epoxy resin (EP) was modified using two different nano-sized ceramics: silicium dioxide (SiO2) and zirconium dioxide (ZrO2); and micro-sized particles of silicone rubber (SR) as second filler. Series of nanocomposites and hybrid modified epoxy resins were obtained by systematic variation of filler contents. The rheology and curing process of the modified epoxy resins were determined in order to define their aptness to be processed by RTM. The resulting matrices were extensively characterized qualitatively and quantitatively to precise the effect of each filler on the polymer properties. It was shown that the nanoparticles confer better mechanical properties to the epoxy resin, including modulus and toughness. It was possible to improve simultaneously the tensile modulus and toughness of the epoxy matrix in more than 30 % and 50 % respectively, only by using 8 vol.-% nano-SiO2 as filler. A similar performance was obtained by nanocomposites containing zirconia. The epoxy matrix modified with 8 vol.-% ZrO2 recorded tensile modulus and toughness improved up to 36% and 45% respectively regarding EP. On the other hand, the addition of silicone rubber to EP and nanocomposites results in a superior toughness but has a slightly negative effect on modulus and strength. The addition of 3 vol.-% SR to the neat epoxy and nanocomposites increases their toughness between 1.5 and 2.5 fold; but implies also a reduction in their tensile modulus and strength in range 5-10%. Therefore, when the right proportion of nanoceramic and rubber were added to the epoxy resin, hybrid epoxy matrices with fracture toughness 3 fold higher than EP but also with up to 20% improved modulus were obtained. Widespread investigations were carried out to define the structural mechanisms responsible for these improvements. It was stated, that each type of filler induces specific energy dissipating mechanisms during the mechanical loading and fracture processes, which are closely related to their nature, morphology and of course to their bonding with the epoxy matrix. When both nanoceramic and silicone rubber are involved in the epoxy formulation, a superposition of their corresponding energy release mechanisms is generated, which provides the matrix with an unusual properties balance. From the modified matrices glass fiber reinforced RTM-plates were produced. The structure of the obtained composites was microscopically analyzed to determine their impregnation quality. In all cases composites with no structural defects (i.e. voids, delaminations) and good superficial finish were reached. The composites were also properly characterized. As expected the final performance of the GFRCs is strongly determined by the matrix properties. Thus, the enhancement reached by epoxy matrices is translated into better GFRC´s macroscopical properties. Composites with up to 15% enhanced strength and toughness improved up to 50%, were obtained from the modified epoxy matrices

Early Mesozoic tectonic transition of the eastern South China Block: constraints from Late Triassic Dashuang complex in eastern Zhejiang Province

<p>The Mesozoic tectonic transition from the Palaeo-Tethys tectonic regime to the Palaeo-Pacific tectonic regime in the eastern South China Block has long been debated. Geochemical and zircon U–Pb–Hf isotopic studies were conducted on the Dashuang complex in the eastern Zhejiang Province. The Dashuang complex consists mainly of quartz syenite in the northwestern part and quartz monzonite in the southeastern part. New laser ablation inductively coupled plasma mass spectrometry zircon U–Pb data show that the quartz syenite, the quartz monzonite, and its chilled margin (fine-grained granite) crystallized at 235 ± 4 Ma, 232 ± 3 Ma, and 230 ± 1 Ma, respectively. The Dashuang complex intrudes into the Chencai Group gneiss that postdated ~646 Ma and underwent anatexis at 443 ± 14 Ma. The quartz monzonite shows A-type granite affinity, characterized by high K₂O + Na₂O and Zr + Nb + Ce + Y, high FeO_T/(MgO + FeO_T) and Ga/Al ratios, an enrichment in light rare earth elements, and depletions in Ba, Sr, and Eu. The quartz monzonite has zircon ε_Hf(<i>t</i>) values of −14.2 to –11.9 and two-stage model ages of 1788–1922 Ma. Zircon ε_Hf(<i>t</i>) values of the chilled margin (fine-grained granite) and wall rock (gneiss) are scattered (−18.2 to –6.3 and −19.5 to 10.2). The corresponding two-stage model ages are 1482–2133 Ma and 1184–2471 Ma, respectively. The Dashuang complex was derived mainly from partial melting of Neoproterozoic clastic rocks in the Cathaysia Block. Geochemical data indicate that the quartz monzonite formed in a post-collision extensional environment. These results, considered with previous data, indicate that the transition from the Palaeo-Tethys to the Palaeo-Pacific tectonic regimes of the eastern South China Block occurred during the Late Triassic (225–215 Ma).</p

EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90°, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 °C

EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90°, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 °C

EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90°, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 °C

EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90°, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 °C

EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90°, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 °C

EBiIn-Cu-GaIn Composite Electrodes inside Microfluidic Chips

Fusible metal electrodes are one of the hot research topics today and have been more widely used in the field of microfluidics. Although many microfabrication-based techniques have been widely applied to various microstructures, current research is still unable to satisfy the use of electrodes in some extreme environments, such as the warning of electrodes in the case of thermal runaway (high temperature and high mechanical stress) in electric vehicles. In order to make the electrodes more adaptable to various environments, we have developed a method to fabricate EBiIn-Cu-GaIn composite electrodes within a single-layer microfluidic channel using a galvanic replacement reaction. The composite electrodes, which combine the advantages of miniaturization, flexibility, good mechanical properties, and high-temperature resistance, can withstand bending at 90°, stretching at 230%, and pressure at 2.7 MPa. The composite electrode was also used to fabricate a miniature heater with a heating temperature of up to 278 °C

DataSheet1_Head-to-head comparison of azvudine and nirmatrelvir/ritonavir for the hospitalized patients with COVID-19: a real-world retrospective cohort study with propensity score matching.docx

Background: Nirmatrelvir/ritonavir and azvudine have been approved for the early treatment of COVID-19 in China, however, limited real-world data exists regarding their effectiveness and safety.Methods: We conducted a retrospective cohort study involving the hospitalized COVID-19 patients in China between December 2022 and January 2023. Demographic, clinical, and safety variables were recorded.Results: Among the 6,616 hospitalized COVID-19 patients, we included a total of 725 patients including azvudine recipients (N = 461) and nirmatrelvir/ritonavir (N = 264) recipients after exclusions and propensity score matching (1:2). There was no significant difference in the composite disease progression events between azvudine (98, 21.26%) and nirmatrelvir/ritonavir (72, 27.27%) groups (p = 0.066). Azvudine was associated with a significant reduction in secondary outcomes, including the percentage of intensive care unit admission (p = 0.038) and the need for invasive mechanical ventilation (p = 0.035), while the in-hospital death event did not significantly differ (p = 0.991). As for safety outcomes, 33 out of 461 patients (7.16%) in azvudine group and 22 out of 264 patients (8.33%) in nirmatrelvir/ritonavir group experienced drug-related adverse events between the day of admission (p = 0.565).Conclusion: In our real-world setting, azvudine treatment demonstrated similar safety compared to nirmatrelvir/ritonavir in hospitalized COVID-19 patients. Additionally, it showed slightly better clinical benefits in this population. However, further confirmation through additional clinical trials is necessary.</p

MoS₂/MnO₂ Nanoparticles Loaded with 2,2′-Azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride for Chemodynamic/Photothermal Antibacterial Applications

Drug-resistant bacterial infections pose a significant threat to global public health. Furthermore, the formation of biofilms makes traditional antibiotic treatments significantly less effective in killing multidrug-resistant (MDR) bacteria. In this work, we prepared a molybdenum disulfide (MoS2) nanosphere-based nanocomposite that utilized both photothermal therapy (PTT) and chemodynamic therapy (CDT) for effectively eradicating biofilms. A layer of manganese dioxide (MnO2) was adsorbed onto the surface of the MoS2 nanospheres by redox and electrostatic adsorption methods, and the resulting MoS2/MnO2 were loaded with 2,2′-azobis[2-(2-imidazolin-2-yl)propane]-dihydrochloride (AIPH) to form the MoS2/MnO2-AIPH nanocomposite (MMA). The microenvironment of biofilms is slightly acidic, lacks oxygen, and has a high concentration of glutathione (GSH). The MnO2 was capable of reacting with GSH to deplete it while also generating •OH radicals for CDT. In the presence of NIR light (808 nm), the temperature increase brought about by PTT further enhanced the CDT efficacy synergistically. The results showed that the photothermal conversion efficiency of the MMA was 40.5% at a concentration of 100 μg/mL, and the biofilm eradication rate of both MDR Escherichia coli and MDR Staphylococcus aureus was above 90%. The high bacterial inhibition rate (above 96%), as well as the excellent biosafety and biocompatibility of the MMA nanocomposite enabled it to effectively promote wound healing, which has significant implications in treating bacterial infections and promoting wound healing in clinical settings