Saline irrigation and wound infection in abdominal gynecologic surgery.

OBJECTIVE: To evaluate whether saline wound irrigation decreases the incidence of wound infection following abdominal gynecologic surgery. METHOD: In this prospective randomized study, 104 patients underwent wound irrigation before wound closure following abdominal gynecologic surgery and 102 patients did not. RESULTS: There were no significant differences between the 2 groups in patient characteristics or in factors influencing the incidence of wound infection after abdominal gynecologic surgery. The incidence of wound infection was 10.6% among women who underwent wound irrigation and 9.8% among those who did not, and the difference was not statistically significant. CONCLUSION: Saline wound irrigation before abdominal wall closure is not helpful in decreasing the incidence of wound infection after abdominal gynecologic surgery.     

树脂加强型玻璃离子黏结剂黏结力的实验研究

目的 了解光固化树脂加强型玻璃离子水门汀的剪切强度能否满足临床需要;并比较不同条件下其剪切强度的变化.方法 收集离体前磨牙50颗,随机均分为5组.第1组(对照组):35%磷酸酸蚀30s,冲洗、干燥,涂黏结剂,采用京津釉质黏结剂黏结托槽.第2、4组:35%磷酸酸蚀30s,冲洗,湿润,采用光固化型的Fuji Ortho Lc树脂加强型玻璃离子黏结托槽.第3、5组:不酸蚀,采用光固化型的Fuji Ortho Lc树脂加强型玻璃离子黏结托槽.1、2、3组用电子万能实验机测24h的抗剪切强度,4、5组测30 min的抗剪切强度.并统计牙面上的黏结剂残留量.结果 第2、3、4组的抗剪切强度均能满足临床需要,第5组的抗剪切强度不能满足临床需要,第2组的抗剪切强度与其它各组相比差别有显著性.结论 光固化树脂加强型玻璃离子在酸蚀和免酸蚀后24h,以及酸蚀黏结30min后的剪切强度均能满足临床需要;而免酸蚀黏结30min的抗剪切强度不能满足临床需要;酸蚀后光固化树脂加强型玻璃离子的剪切强度明显增强.     

ZTA和Al2O3正畸托槽的研究

目的 分别评价ZTA(ZrO2增韧Al2O3)和Al2O3陶瓷的性能,探索一种适合制备正畸托槽的陶瓷材料.方法 选用ZrO2(3mol%Y2O3)和α-Al2O3粉体作为原料,利用热压铸成型工艺制备陶瓷托槽,在1600 ℃下烧结.将制得样品进行各方面的性能测试.结果 采用纯Al2O3制备的托槽抗弯强度远远低于ZTA复合陶瓷.结论 牙科正畸托槽可以选用具有较高抗弯强度的ZTA复合陶瓷作为原料.     

纳米金刚石改性核树脂与纤维桩的微拉伸粘结强度研究

目的：测试自行合成的纳米金刚石改性的核树脂（UFD-C）与三种材料纤维桩的微拉伸粘结强度.方法：选择石英纤维桩、玻璃纤维桩、碳纤维桩各10个,每种随机分成2组.在桩周分别用UFD-C或Luxa-Core（L-C）商品核树脂充填,用低速锯沿纤维桩外周平行片切,再垂直粘结面片切成约0.9mm×0.9mm的长方形柱状试件,每组共15个试件.测试其粘结强度,并观察其断裂类型.结果：UFD-C与三种纤维桩的微拉伸粘结强度分别为20.08±2.79 MPa、17.78±5.70 MPa、20.12±3.78 MPa;L-C与三种纤维桩的微拉伸粘结强度分别为21.09±3.64 MPa、23.55±3.41 MPa、18.12±3.80 MPa.L-C与玻璃纤维桩的微拉伸粘结强度高于UFD-C与玻璃纤维桩,差异有统计学意义（P＜0.05）,2种核树脂与石英纤维桩和碳纤维桩的粘结强度差异无显著性（P＞0.05）.体视显微镜观察92%试件是粘结界面的断裂.结论：纳米金刚石改性核树脂与石英纤维桩、碳纤维桩的微拉伸粘结强度与商品Luxa-Core核树脂相当,能满足牙体缺损修复的要求.     

不同溶剂的酒石酸酸蚀对黏结强度影响的研究

目的观察用不同溶剂的酒石酸酸蚀牙釉质表面对黏结强度的影响。方法40颗前磨牙随机分为4组,分别用10%的酒石酸水溶液、10%酒石酸乙醇水溶液、10%酒石酸丙酮水溶液及37%磷酸酸蚀(对照组)前磨牙颊面牙釉质表面后,用京津釉质黏合剂黏结舌侧扣。通过电子万能实验机测量记录舌侧扣在轴向拉力作用下脱位的张力强度。结果用37%磷酸酸蚀、10%的酒石酸水溶液酸蚀、10%酒石酸乙醇水溶液酸蚀、10%酒石酸丙酮水溶液酸蚀牙釉质后,京津釉质黏合剂黏结舌侧扣脱位的张力强度分别为(4.12±1.11)MPa、(4.42±1.64)MPa、(2.57±0.75)MPa、(2.65±1.22)MPa,4者间有显著性差异(P<0.01)。结论不同溶剂的酒石酸酸蚀对黏结强度有一定的影响。     

Estimation of Nanoporous Au Young’s Modulus from Serial Block Face-SEM 3D-Characterisation

Nanoporous Au has been subjected to serial block face-scanning electron microscopy (SBF-SEM) 3D-characterisation. Corresponding sections have been digitalized and used to evaluate the associated mechanical properties. Our investigation demonstrates that the sample is homogeneous and isotropic. The effective Young’s modulus estimated by an analytical multiscale approach agrees remarkably well with the values stated in the literature.     

Infill Density Influence on Mechanical and Thermal Properties of Short Carbon Fiber-Reinforced Polyamide Composites Manufactured by FFF Process

In three-dimensional (3D) printing, one of the main parameters influencing the properties of 3D-printed materials is the infill density (ID). This paper presents the influence of ID on the microstructure, mechanical, and thermal properties of carbon fiber-reinforced composites, commercially available, manufactured by the Fused Filament Fabrication (FFF) process. The samples were manufactured using FFF by varying the infill density (25%, 50%, 75%, and 100%) and were subjected to tensile tests, three-point bending, and thermal analyses by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). It was shown that the samples with 100% ID had the highest values of both tensile, 90.8 MPa, and flexural strengths, 114 MPa, while those with 25% ID had the lowest values of 56.4 MPa and 62.2 MPa, respectively. For samples with infill densities of 25% and 50%, the differences between the maximum tensile and flexural strengths were small; therefore, if the operating conditions of the components allow, a 25% infill density could be used instead of 50%. After DSC analysis, it was found that the variation in the ID percentage determined the change in the glass transition temperature from 49.6 °C, for the samples with 25% ID, to 32.9 °C, for those with 100% ID. TGA results showed that the samples with IDs of 75% and 100% recorded lower temperatures of onset degradation (approximately 344.75 °C) than those with infill densities of 25% and 50% (348.5 °C, and 349.6 °C, respectively).     

Liquid Guayule Natural Rubber,a Sustainable Processing Aid,Enhances the Processability,Durability and Dynamic Mechanical Properties of Rubber Composites

Petroleum-based oils are widely used as processing aids in rubber composites to improve processability but can adversely affect rubber composite performance and increase carbon footprint. In this research, liquid guayule natural rubber (LGNR), produced from guayule natural rubber, was used as a renewable processing aid to replace naphthenic oil (NO) in Hevea natural rubber, styrene-butadiene rubber (SBR) and guayule natural rubber (GNR) composites. The rheological properties, thermal stability, glass transition temperature, dynamic mechanical properties, aging, and ozone resistance of rubber composites with and without NO or LGNR were compared. Natural and synthetic rubber composites made with LGNR had similar processability to those made with NO, but had improved thermal stability, mechanical properties after aging, and ozone resistance. This was due to the strong LGNR–filler interaction and additional crosslinks formed between LGNR and the rubber matrices. The glass transition temperature of SBR composites was reduced by LGNR because of its increased molecular mobility. Thus, unlike NO, LGNR processing aid can simultaneously improve rubber composite durability, dynamic performance and renewability. The commercialization of LGNR has the potential to open a new sustainable processing-aid market.     

Burst Pressure Prediction of Subsea Supercritical CO2 Pipelines

To improve transportation efficiency, a supercritical CO₂ pipeline is the best choice for large-scale and long-distance transportation inshore and offshore. However, corrosion of the pipe wall will occur as a result of the presence of free water and other impurities present during CO₂ capture. Defects caused by corrosion can reduce pipe strength and result in pipe failure. In this paper, the burst pressure of subsea supercritical CO₂ pipelines under high pressure is investigated. First, a mechanical model of corroded CO₂ pipelines is established. Then, using the unified strength theory (UST), a new burst pressure equation for subsea supercritical CO₂ pipelines is derived. Next, analysis of the material’s intermediate principal stress parameters is conducted. Lastly, the accuracy of the burst pressure equation of subsea supercritical CO₂ pipelines is proven to meet the engineering requirement by experimental data. The results indicate that the parameter b of UST plays a significant role in determining burst pressure of pipelines. The study can provide a theoretical basis and reference for the design of subsea supercritical CO₂ pipelines.     

根管锥度和循环疲劳对牙根力学性能的影响

目的：分析根管预备锥度和循环疲劳对离体牙根力学性能的影响。方法：将32颗离体下颌第一前磨牙随机分成4组,每组8颗牙齿,截冠后将每组的牙根分别预备成0.02、0.04、0.06、0.08锥度,使用侧方加压充填根管。随后每组中随机抽取4颗牙根做循环疲劳实验,疲劳前后均做扫描电镜观察牙根表面形态,最后对所有牙根进行抗压强度测试。结果：各锥度组随锥度的增大牙根抗压强度值有降低趋势,但无统计学差异（P〉0.05）;疲劳实验后0.08锥度牙根表面裂纹明显多于疲劳前,疲劳实验中实验组和对照组两组离体牙根抗压强度值无统计学差异（P〉0.05）;且疲劳和锥度两因素之间没有交互作用（P〉0.05）。结论：根管预备后锥度在0.08以内对牙根的整体抗压性能和抗疲劳性能无明显影响。