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排序方式: 共有745条查询结果,搜索用时 15 毫秒
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Ivan A. Pelevin Anton Yu. Nalivaiko Dmitriy Yu. Ozherelkov Alexander S. Shinkaryov Stanislav V. Chernyshikhin Alexey N. Arnautov Sergey V. Zmanovsky Alexander A. Gromov 《Materials》2021,14(10)
Aluminum matrix composites (AMC) are of great interest and importance as high-performance materials with enhanced mechanical properties. Al2O3 is a commonly used reinforcement in AMCs fabricated by means of various technological methods, including casting and sintering. Selective laser melting (SLM) is a suitable modern method of the fabrication of net-shape fully dense parts from AMC with alumina. The main results, achievements, and difficulties of SLM applied to AMCs with alumina are discussed in this review and compared with conventional methods. It was shown that the initial powder preparation, namely the particle size distribution, sphericity, and thorough mixing, affected the final microstructure and properties of SLMed materials drastically. The distribution of reinforcing particles tends to consolidate the near-melting pool-edges process because of pushing by the liquid–solid interface during the solidification process that is a common problem of various fabrication methods. The achievement of an homogeneous distribution was shown to be possible through both the thorough mixing of the initial powders and the precise optimization of SLM parameters. The strength of the AMCs fabricated by the SLM method was relatively low compared with materials produced by conventional methods, while for superior relative densities of more than 99%, hardness and tribological properties were obtained, making SLM a promising method for the Al-based matrix composites with Al2O3. 相似文献
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《Vaccine》2020,38(39):6141-6152
Influenza vaccination is considered the most valuable means to prevent and control seasonal influenza infections, which causes various clinical symptoms, ranging from mild cough and fever to even death. Among various influenza vaccine types, the inactivated subunit type is known to provide improved safety with reduced reactogenicity. However, there are some drawbacks associated with inactivated subunit type vaccines, with the main ones being its low immunogenicity and the induction of Th2-biased immune responses. In this study, we investigated the role of a single-stranded RNA (ssRNA) derived from the intergenic region in the internal ribosome entry site of the Cricket paralysis virus as an adjuvant rather than the universal vaccine for a seasonal inactivated subunit influenza vaccine. The ssRNA adjuvant stimulated not only well-balanced cellular (indicated by IgG2a, IFN-γ, IL-2, and TNF-α) and humoral (indicated by IgG1 and IL-4) immune responses but also a mucosal immune response (indicated by IgA), a key protector against respiratory virus infections. It also increases the HI titer, the surrogate marker of influenza vaccine efficacy. Furthermore, ssRNA adjuvant confers cross-protective immune responses against heterologous influenza virus infection while promoting enhanced viral clearance. Moreover, ssRNA adjuvant increases the number of memory CD4+ and CD8+ T cells, which can be expected to induce long-term immune responses. Therefore, this ssRNA-adjuvanted seasonal inactivated subunit influenza vaccine might be the best influenza vaccine generating robust humoral and cellular immune responses and conferring cross-protective and long-term immunity. 相似文献
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Exfoliated nanocomposites of chitosan-magnesium aluminum silicate (CS-MAS) particles are characterized by good compressibility but poor flowability. Thus, the aims of this study were to investigate agglomerates of CS-MAS nanocomposites prepared using the agglomerating agents water, ethanol, or polyvinylpyrrolidone (PVP) for flowability enhancement and to evaluate the agglomerates obtained as direct compression fillers for tablets. The results showed that the addition of agglomerating agents did not affect crystallinity, but slightly influenced thermal behavior of the CS-MAS nanocomposites. The agglomerates prepared using water were larger than those prepared using 95% ethanol because high swelling of the layer of chitosonium acetate occurred, allowing formation of solid bridges and capillary force between particles, leading to higher flowability and particle strength. Incorporation of PVP resulted in larger agglomerates with good flowability and high strength due to the binder hardening mechanism. The tablets prepared from agglomerates using water showed lower hardness, shorter disintegration times and faster drug release than those using 95% ethanol. In contrast, greater hardness and more prolonged drug release were obtained from the tablets prepared from agglomerates using PVP. Additionally, the agglomerates of CS-MAS nanocomposites showed good carrying capacity and provided desirable characteristics of direct compression tablets. 相似文献
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牙科渗透陶瓷用着色玻璃粉的制备与性能研究 总被引:4,自引:1,他引:4
目的:研究渗透陶瓷用着色玻璃粉的制备方法与相关性能。方法:将玻璃原料混匀烘干后放入氧化铝坩埚,在1400℃下熔融2h制成玻璃,测试玻璃的各种物理及力学性能。结果:差热分析显示玻璃的转换温度在690℃,在20℃-600℃之间,玻璃的热膨胀系数为6.2×10-6℃-1 ,密度2.23g/cm3,抗弯强度118Mpa,断裂韧性1.22Mpam1/2,维氏硬度7.4GPa。结论: 本研究所添加着色氧化物不影响渗透玻璃的物理及力学性能,制备的着色玻璃粉与多孔氧化铝预烧体有良好的物理与化学匹配性。 相似文献
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OBJECTIVES: To determine whether magnesium-aluminum-hydroxide-simethicone suspension (MgAl) is an effective treatment for dermal capsaicin exposures. METHODS: The authors performed a double-blind, randomized, controlled, pilot study comparing the effect of MgAl with that of saline in the treatment of dermal capsaicin exposures. Ten volunteers were sprayed with a commercial defensive spray containing 10% capsaicin on the flexor surface of both forearms. A dressing embedded with MgAl (Maalox) suspension was randomly applied to one arm and a saline-embedded dressing was applied to the other arm. Pain was assessed on a 10-cm visual analog scale at 0, 10, 20, 30, 60, 90, and 120 minutes. RESULTS: Mean pain scores were significantly lower in the MgAl group as compared with the saline (S) group at 10, 20, and 30 minutes. Differences in pain scores were not statistically significant at times 60, 90, and 120 minutes. CONCLUSIONS: During the initial 30 minutes of treatment, there was a statistically significant decrease in pain scores with MgAl as compared with saline treatments. Although the difference in means may have questionable clinical significance, MgAl is cheap and readily available, and has minimal side effects. Thus, MgAl may be an appropriate treatment for dermal capsaicin exposure. 相似文献
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Introduction
High Power Laser therapy (HPLT) can damage tissues due to its high skin absorption and side effects. The objective of this study was to determine the protective effect of human adipose-derived stem cells (hADSCs) against HPLT-mediated fat tissue damage after fat grafts in an in vivo study.Methods
To determine the viability of fat grafts with transplanted hADSCs, high power laser (HPL) irradiation was performed using a 830?nm gallium–aluminum–arsenide (Ga–Al–As) laser. In the in vivo study, fat grafts with hADSCs/Dulbecco’s modified Eagle’s medium (DMEM) were transplanted and HPL irradiation of each nude mouse was performed per protocol for a period of 13 weeks. Vascular endothelial growth factor (VEGF) and cluster of differentiation 31 (CD31) levels of hADSCs were quantified by immunofluorescent staining using anti-VEGF antibody and anti-CD31 antibody, respectively, along with human mitochondrial (hMT) antibody.Results
Compared to the HPLT?+?DMEM group, HPLT?+?hADSCs group showed increase in the number of viable cells of hADSCs in fat grafts, fat graft survival rate (weights and volumes), and expression levels of VEGF and CD31 in treated nude mice. Results of the in vivo study using nude mice and immune cytokine array suggest that hADSCs have potential protective effect against HPLT-mediated fat tissue damage.Discussion
hADSCs could be applied in clinical fields by inhibiting HPLT-mediated side effects. 相似文献10.