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1.
目的 研究不同浓度细菌脂多糖(Lipopolysaccharides,LPS)对选择性激光熔化技术(Selective laser melting,SLM)制作的钴铬钼合金腐蚀行为的影响。方法 分别以SLM法及铸造法各制作12个钴铬钼合金试件,根据在腐蚀电解液中LPS浓度(0、0.15、15、150 μg/mL)不同分为4组,每组3个试件。采用电化学阻抗谱、动电位极化测试法分析2组合金试件在不同浓度脂多糖(LPS)中的腐蚀行为。结果 在单纯人工唾液中,SLM合金和铸造合金的腐蚀参数无统计学上的差异(P> 0.05)。当LPS浓度为150 μg/mL时,SLM合金和铸造合金的电阻(Rp)均显著下降且自腐蚀电流密度(Icorr)显著增大,但SLM合金的Rp值大于铸造合金且Icorr值较小(P< 0.05)。结论 LPS对SLM法和铸造法制作的钴铬钼合金的腐蚀行为均有不利影响,但对SLM法制作的合金的腐蚀影响小于铸造法制得的合金。  相似文献   
2.
为了在腰椎退变性疾病保守治疗和融合手术中间地带寻找一种有效的预防与辅助相结合的微创治疗方式,通过对比目前常用的几种腰椎棘突间动态稳定系统的临床疗效观察和优缺点,以及对腰椎棘突间的生理结构、生物力学和相关数据的分析,在充分了解记忆合金材质的基础上,自行设计研究一种记忆合金材料的新型腰椎棘突间动态固定装置,既能重建腰椎的正常生物力学特性,满足人体脊柱的正常活动,又避免对原有结构的破坏,减少术后并发症的发生,同时也可以优化目前的治疗方法。通过研究,腰椎棘突间记忆合金动态稳定装置在理论上效果满意,可以解决现有技术的不足,优于目前的几种腰椎棘突间动态稳定系统。  相似文献   
3.
目的 探讨微弧氧化(MAO)表面改性3D打印多孔钛合金支撑棒对羊距骨坏死的治疗作用,为其进一步临床应用提供基础。方法 观察3D打印多孔钛合金支撑棒通过MAO表面改性后,其表面形态、元素变化及晶像情况。通过体外细胞实验,研究大鼠成骨细胞在材料表面的黏附、增殖及分化情况。建立羊距骨坏死模型基础,并置入3D打印多孔钛合金支撑棒,探究其在距骨内的稳定性及其成骨修复情况。结果 通过MAO改性,材料表面形成大小均一的多孔微米结构,Ca、P、O元素分布在材料表面,同时表面形成TiO2晶像。在体外细胞实验中,MAO改性组和对照组均表现出良好的生物相容性,但是MAO改性组在细胞接种后8 h黏附能力优于对照组、接种1、4、7 d后细胞增殖能力均优于对照组,同时接种7 d时细胞分化能力也优于对照组,差异具有统计学意义(P<0.05)。羊距骨植入实验表明,术后12周两组支撑棒都有骨长入,但是MAO改性组与对照组相比其周围有更多的新生骨长入。定量结果显示MAO组的骨体积分数、骨小梁厚度也优于对照组,差异具有统计学意义(P<0.05)。结论 仿生的3D打印多孔结构为支撑棒提供了优良的力学性能,MAO表面改性进一步提高了其生物活性,使其在治疗羊距骨早期骨坏死过程中充分发挥了力学和生物学的优势。本临床前研究效果满意,并为其未来临床应用提供了理论和研究基础。  相似文献   
4.
Epidemiological studies on magnesium intake and primary liver cancer (PLC) are scarce, and no prospective studies have examined the associations of magnesium intake with PLC incidence and mortality. We sought to clarify whether higher magnesium intake from diet and supplements was associated with lower risks of PLC incidence and mortality in the US population. Magnesium intake from diet and supplements was evaluated through a food frequency questionnaire in a cohort of 104,025 participants. Cox regression was employed to calculate hazard ratios for PLC incidence and competing risk regression was employed to calculate subdistribution hazard ratios for PLC mortality. Restricted cubic spline regression was employed to test nonlinearity. We documented 116 PLC cases during 1,193,513.5 person-years of follow-up and 100 PLC deaths during 1,198,021.3 person-years of follow-up. Total (diet + supplements) magnesium intake was found to be inversely associated with risks of PLC incidence (hazard ratiotertile 3 vs. 1: 0.44; 95% confidence interval: 0.24, 0.80; ptrend = 0.0065) and mortality (subdistribution hazard ratiotertile 3 vs. 1: 0.37; 95% confidence interval: 0.19, 0.71; ptrend = 0.0008). Similar results were obtained for dietary magnesium intake. Nonlinear inverse dose–response associations with PLC incidence and mortality were observed for both total and dietary magnesium intakes (all pnonlinearity < 0.05). In summary, in the US population, a high magnesium intake is associated with decreased risks of PLC incidence and mortality in a nonlinear dose–response manner. These findings support that increasing the consumption of foods rich in magnesium may be beneficial in reducing PLC incidence and mortality.  相似文献   
5.
We, herein, report the first use of a Magmaris® magnesium‐based vascular scaffold for native aortic coarctation in a 1,980 g infant with multiple malformations. Due to the low body weight, complex illness, and clinical instability, it was decided to delay surgical correction. After insufficient results had been obtained by balloon angioplasty, Magmaris® implantation was chosen to bridge the patient to surgery by stabilizing left ventricular function and to allow for sufficient growth. Due to significant early stent restenosis and complete loss of radial force, the patient required balloon reangioplasty only 21 days after Magmaris® implantation and early surgical correction. In addition, high systemic sirolimus levels were detected 48 hr after the intervention (5 ng/mL). Although the bioresorbable scaffold was successfully used as a short‐term bridge‐to‐surgery in our case, due to significant early stent failure (loss of radial force), this approach does not seem promising for long‐term bridging of infants with aortic coarctation. In addition, the consequences of sirolimus‐induced systemic immunosuppression may further limit the applicability of Magmaris® scaffolds in infants with congenital heart disease.  相似文献   
6.
目的:探讨异甘草酸镁(MgIG)对四氯化碳(CCl4)致大鼠肝纤维化模型肝细胞数量与体积的影响。方法: 雄性SD大鼠随机分为对照组、模型组、治疗组,治疗组给予CCl4 皮下注射,同时每日腹腔注射MgIG 30 mg/ kg。 各组大鼠在造模5 周后取材,从每只大鼠等距抽选4 个2 mm厚的肝组织块制作石蜡包埋切片,行Masson 染色, 采用体视学方法测量大鼠肝细胞体积与数量,以及肝细胞胞质内脂滴体积。结果:与对照组比较,模型组、治疗 组大鼠肝细胞的平均体积分别显著增加了91.9% 和105.0%,肝细胞胞质内脂滴的总体积分别显著增加了5.27 倍 与4.83 倍,肝细胞的总数量分别显著减少了40.0% 和42.4% ;与模型组比较,治疗组大鼠每个肝细胞平均体积、 肝细胞胞质内脂滴的总体积以及肝细胞的总数量之间的差异均无统计学意义。结论:CCl4 所致大鼠肝纤维化伴随 着肝细胞肿胀、脂肪变性及肝细胞数量减少等病理改变,MgIG 对CCl4 致肝细胞的病理改变无显著作用。  相似文献   
7.
This study investigates the very-high-cycle fatigue (VHCF) behavior at elevated temperature (650 °C) of the Inconel 718 alloy fabricated by selective laser melting (SLM). The results are compared with those of the wrought alloy. Large columnar grain with a cellular structure in the grain interior and Laves/δ phases precipitated along the grain boundaries were exhibited in the SLM alloy, while fine equiaxed grains were present in the wrought alloy. The elevated temperature had a minor effect on the fatigue resistance in the regime below 108 cycles for the SLM alloy but significantly reduced the fatigue strength in the VHCF regime above 108 cycles. Both the SLM and wrought specimens exhibited similar fatigue resistance in the fatigue life regime of fewer than 107–108 cycles at elevated temperature, and the surface initiation mechanism was dominant in both alloys. In a VHCF regime above 107–108 cycles at elevated temperature, the wrought material exhibited slightly better fatigue resistance than the SLM alloy. All fatigue cracks are initiated from the internal defects or the microstructure discontinuities. The precipitation of Laves and δ phases is examined after fatigue tests at high temperatures, and the effect of microstructure on the formation and the propagation of the microstructural small cracks is also discussed.  相似文献   
8.
This paper is focused on the mechanical properties and the energy absorption characteristics of the extruded Mg-Al-Ca-Mn alloy in different compression directions under high strain rate compression. Compressive characterization of the alloy was conducted from the high strain rate (HSR) test by using a Split Hopkinson Pressure Bar (SHPB). Results show that the investigated alloy exhibits a strong strain rate sensitivity. With the rise of strain rate, the compressive strength is increased significantly, and the deformation ability also improves. When compressed along the extrusion direction, as the strain rate increases, the total absorbed energy E, the crush force efficiency (CFE), and the specific energy absorption SEA of Mg-Al-Ca-Mn alloy are all greatly improved as compared with those obtained along other compression directions.  相似文献   
9.
Porous anodic alumina oxide (AAO) obtained via two-step anodization is a material commonly used as a template for fabricating 1D nanostructures. In this work, copper and cobalt-iron 1D nanocones were obtained by an electrodeposition method using AAO templates. The templates were produced using two-step anodization in H2C2O4. The Co–Fe nanostructures are characterized by homogeneous pore distribution. The electrocatalytic activity of the produced nanomaterials was determined in 1 M NaOH using the linear sweep voltammetry (LSV) and chronopotentiometry (CP) methods. These materials can be used as catalysts in the water-splitting reaction. The sample’s active surface area was calculated and compared with bulk materials.  相似文献   
10.
We performed biological safety evaluation tests of three Ti–Zr alloys under accelerated extraction condition. We also conducted histopathological analysis of long-term implantation of pure V, Al, Ni, Zr, Nb, and Ta metals as well as Ni–Ti and high-V-containing Ti–15V–3Al–3Sn alloys in rats. The effect of the dental implant (screw) shape on morphometrical parameters was investigated using rabbits. Moreover, we examined the maximum pullout properties of grit-blasted Ti–Zr alloys after their implantation in rabbits. The biological safety evaluation tests of three Ti–Zr alloys (Ti–15Zr–4Nb, Ti–15Zr–4Nb–1Ta, and Ti–15Zr–4Nb–4Ta) showed no adverse (negative) effects of either normal or accelerated extraction. No bone was formed around the pure V and Ni implants. The Al, Zr, Nb, and Ni–Ti implants were surrounded by new bone. The new bone formed around Ti–Ni and high-V-containing Ti alloys tended to be thinner than that formed around Ti–Zr and Ti–6Al–4V alloys. The rate of bone formation on the threaded portion in the Ti–15Zr–4Nb–4Ta dental implant was the same as that on a smooth surface. The maximum pullout loads of the grit- and shot-blasted Ti–Zr alloys increased linearly with implantation period in rabbits. The pullout load of grit-blasted Ti–Zr alloy rods was higher than that of shot-blasted ones. The surface roughness (Ra) and area ratio of residual Al2O3 particles of the Ti–15Zr–4Nb alloy surface grit-blasted with Al2O3 particles were the same as those of the grit-blasted Alloclassic stem surface. It was clarified that the grit-blasted Ti–15Zr–4Nb alloy could be used for artificial hip joint stems.  相似文献   
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