Antibiofilm and Protein-Repellent Polymethylmethacrylate Denture Base Acrylic Resin for Treatment of Denture Stomatitis

Candida albicans (C. albicans) biofilm is a common etiological factor in denture stomatitis. The purpose of this study was to investigate the effects of incorporating 2-methacryloyloxyethyl phosphorylcholine (MPC) as a protein repellent into a new high-impact denture acrylic (HIPA) resin on the surface roughness, solution pH, and C. albicans biofilm adhesion to the denture base. The new acrylic denture resin base was formulated by mixing MPC into HIPA resin at mass fractions of 1.5%, 3%, and 4.5%. Surface roughness was measured using a Mitutoyo surface roughness tester. C. albicans biofilm growth and viability were assessed via colony forming unit counts. The pH of the biofilm growth medium was measured using a digital pH meter. Adding MPC to the HIPA resin at percentages of 1.5% and 3% increased the roughness values significantly (p < 0.05), while adding 4.5% MPC resulted in no difference in roughness values to that of the control group (p > 0.05). All experimental groups demonstrated neutral pH values (pH ≅ 7) and were not significantly different from each other (p > 0.05). Incorporating 2-methacryloyloxyethyl phosphorylcholine at 4.5% resulted in a significant (≅1 log) colony-forming unit reduction compared with the control group with 0% MPC (p < 0.05). A fungal-retarding denture acrylic resin was developed through the incorporation of MPC for its protein-repelling properties. This newly developed denture acrylic material has the potential to prevent oral microbial infections, such as denture stomatitis.     

血府逐瘀口服液对大鼠缺氧-再给氧损伤心脏微血管内皮细胞黏附分子表达的影响

目的 观察血府逐瘀口服液对心脏微血管内皮细胞缺氧／复氧损伤中黏附分子表达的影响。方法 通过心脏微血管内皮细胞体外培养技术，建立缺氧／复氧损伤模型，模拟心肌缺血再灌注损伤。用免疫细胞化学法和图像定量分析系统，观察心脏微血管内皮细胞的细胞间黏附分子-1（ICAM-1）和血管细胞黏附分子-1（VCAM-1）的表达变化。结果大鼠心脏微血管内皮细胞缺氧4h后ICAM-1和VCAM-1的蛋白表达较对照组升高，但无统计学意义（P〉0．05），再给氧6h、12h后ICAM-1和VCAM一1的表达较对照组明显增高（P〈0．01）。血府逐瘀口服液能显著降低ICAM-1和VCAM-1的蛋白表达，这种作用随着剂量的增加而增强。结论 血府逐瘀口服液可通过降低心脏微血管内皮细胞的ICAM-1和VCAM-1表达，减少白细胞浸润，从而减轻缺血再灌注损伤中的炎性反应对心功能造成损害。     

The Wear of Seal Fins during High-Speed Rub between Labyrinth Seal Fins and Honeycomb Stators at Different Incursion Rates

Labyrinth seals as a noncontact sealing technology are widely used in aero-engine. To improve the efficiency of the aero-engine, the clearance between the rotor and stator must be as small as possible. However, the change of the clearance between the rotor and stator because of thermal expansion, vibration, mechanical loading may lead to undesirable high-speed rub, which will lead to the cracking of the seal fins. This paper focuses on the wear of the seal fin after the rub and presents the rubbing tests between seal fins and the metal honeycomb under rubbing speed of 380 m/s and incursion rates between 20 and 180 μm/s, with an incursion depth of 1500 μm and a temperature of 350 °C. The rubbing force and temperature were recorded, and the seal fins were checked by SEM and EDS. The results show that the wear mechanism of seal fins changed from oxidation wear and adhesive wear to delamination wear and then to metal wear with the increasing incursion rate. The axial cracks appeared on the worn surface of the seal fins due to the cracking of tribo-layers under periodic thermomechanical stress. The wear mechanism of the seal fin also has a great influence on the rubbing force and temperature.     

Accuracy of the Intra- and Extra-Oral Scanning Technique for Transferring the Intaglio Surface of a Pontic of Provisional Restorations to Definitive Restorations

When taking the final impression for a three-unit fixed partial denture (FPD), the intaglio surface of the pontic of provisional restoration cannot be transferred accurately to that of definitive restoration. The intra- and extra-oral scanning (IEOS) technique, a method for accurately reproducing the submucosal morphology of the superstructure of an implant, has been reported using an intraoral scanner. In the present study, we evaluated the difference between the conventional impression method using impression material and the IEOS technique in reproducing the morphology of the surface of the pontic of a definitive FPD. There was a significant difference in the trueness of the intaglio surface morphology of the pontic between the conventional method and the IEOS technique; however, no significant difference in precision was observed. As a result, the intaglio surface of the pontic of the three-unit FPD could be transferred to definitive restorations more accurately with the IEOS technique than with the conventional method. These results suggest that the IEOS technique can duplicate the intaglio surface of the pontic more reproducibly to the definitive restorations compared with the conventional method.     

Comparison of the Masticatory Force (with 3D Models) of Complete Denture Base Acrylic Resins with Reline and Reinforcing Materials

The reinforcement of acrylic denture base remains problematic. Acrylic prosthesis fractures are commonly observed in prosthodontic practice and have not been reliably resolved. This study compared the resistance to masticatory force of acrylic bases of removable complete conventional prosthesis in 3D upper models. Forty acrylic base test specimens containing two types of reinforcement meshes (20 with glass fiber meshes (FIBER-FORCE^®- Synca, Bio Composants Médicaux^TM, Tullins, France), 20 with metal meshes (DENTAURUM^®-Ispringen, Germany)), 20 with a conventional PMMA acrylic base (LUCITONE 199^®-Dentsply Sirona, York, PA, USA), and 20 using a permanent soft reline material (MOLLOPLAST-B^®-DETAX GmbH & Co. KG, Ettlingen, Germany) were tested—a total of 80 specimens. Half of the specimens were made for a low alveolar ridge and half for a high alveolar ridge. The data were analysed using one-way analysis of variance and Student’s t-test for independent test specimens. In the high-alveolar-ridge group, the prosthesis reinforced with the glass fiber mesh was the most resistant to fracture, while in the low-alveolar-ridge group, the non-reinforced prosthesis showed the highest resistance masticatory force. Prostheses with the permanent soft reline material showed the lowest resistance to fracture in both high and low-alveolar-ridge groups. The results show that the selection of the right reinforcement material for each clinical case, based on the height of the alveolar ridge, may help to prevent prosthesis fractures.     

可溶性细胞间粘附分子-1与肝纤维化关系的研究

探讨可溶性细胞间粘附分子－1（sICAM－1）在慢性乙型病毒性肝炎（简称慢性乙肝）、肝硬化（LC）患者的水平及其与肝纤维化的关系。sICAM－1的检测采用ELISA法，并同时检测PCⅢ、LN、HA，以20例健康者体者作对照。慢性乙肝、LC患者血清sICAM－1水平均高于对照组，且随着HC、PCⅢ水平的升高而升高。慢性乙肝、LC患者血清sICAM－1水平升高，可反映肝细胞损伤程度有肝纤维化程度。     

口服不同剂量的碘化油微囊防治地方性甲状腺肿的疗效及有效期观察

本文报告1990～1991年在缺碘性疾病流行区新疆托克逊县观察了一次性口服不同剂量(400、300和200mg)碘化油微囊的防治疗效及尿碘排泄。结果表明,在服药后半年和1年甲状腺肿患病率在不同剂量组均有不同程度的下降,治愈率均有不同程度的提高,但与对照组比较无论患病率还是治愈率均无显著差异(P>0.05)。不同剂量组之间服药后1月内尿碘排泄有随剂量增大相应增高的趋势(P<0.01),但至第三个月时无论是不同剂量组之间还是与对照组之间均未见显著差异(P>0.05)。从而提示,口服碘化油微囊能否作为防治缺碘性疾病的长效补碘方法,很值得商榷。     

青海省相同海拔地区世居汉族与藏族慢性胃炎患者胃黏膜内MDA、SOD、NO、XOD的含量比较

目的 探讨高原地区不同民族世居人群慢性胃炎胃黏膜组织内4种体液因子代谢水平的差异及其意义.方法 检测青海省相同海拔地区世居汉族与世居藏族人群慢性胃炎胃黏膜组织内脂质过氧化物丙二醛（MDA）、超氧化物歧化酶（SOD）、一氧化氮（NO）、黄嘌呤氧化酶（XOD）水平,并将两民族组间相关数据进行比较分析.结果 同海拔地区世居汉族居民胃黏膜组织内MDA含量和SOD活力[（2.2699±1.58908）nmol/mgprot、（134.6313＋48.35329）U/mgport]显著高于世居藏族居民[（1.7095±1.19474）nmol/mgprot、（109.5056±28.26794）U/mgport]（P〈0.05）,提示氧自由基与抗氧自由基代谢存在民族差别;而NO与XOD含量两民族间差异无统计学意义,提示NO与XOD代谢无民族差别.结论 高原地区慢性胃炎胃组织内MDA与SOD代谢水平在世居汉族和世居藏族人群间存在差别,推测世居汉族与世居藏族居民慢性胃炎发病率不同的原因可能是基于不同民族对高原缺氧的耐受能力不同所致.     

Enhancement of Interface between Lignocellulosic Fibers and Polypropylene Matrix via the Structure Alteration of Lignin at Elevated Temperatures

This paper investigated the feasibility of enhancing the interface between lignocellulosic fibers and a polypropylene matrix via structure alteration of lignin at elevated temperatures. Alkali treatment can remove gum substances from lignocellulose fibers effectively at elevated temperatures but easily causes damages to fiber strength. In previous studies on directional delignification of lignocellulosic fibers, loss of fiber strength is avoided but condensation and degradation of lignin are accelerated. So far, few reports have been available on the effect of lignin structures on the interface between fibers and a matrix. In this study, jute fibers with different lignin structures are produced at 100 and 130 °C for reinforcing a polypropylene matrix. The interface between the fibers and matrix is analyzed. The result shows that decrease in aliphatic hydroxyl concentration by 9.5% at 130 °C from 3 to 5 h contributes to a 14.2% decrease in the surface energy of jute fibers. Meanwhile, the polydispersity index of lignin decreases from 1.21 to 1.15. Centralized distribution of lignin molecule-weight and reduction in fiber surface energy improves the interface between the fibers and matrix, which manifests as a 30.8% increase in the impact strength of the composites. Similar improvement is not observed in the composites reinforced with jute fibers at 100 °C, due to the absence of lignin-structure changes. This paper provides a new strategy to improve the interface between lignocellulose fibers and a hydrophobic matrix.     

Understanding the Failure Mechanism of Thermal Barrier Coatings Considering the Local Bulge at the Interface between YSZ Ceramic and Bond Layer

The TC/BC interface morphology in APS TBC is one of the important factors leading to crack propagation and coating failure. Long cracks are found near the bulge on the TC/BC interface. In this study, the TBC model with the bulge on the interface is developed to explore the influence of the bulge on the coating failure. Dynamic TGO growth and crack propagation are considered in the model. The effects of the bulge on the stress state and crack propagation in the ceramic layer are examined. Moreover, the effects of the distribution and number of bulges are also investigated. The results show that the bulge on the interface results in the redistribution of local stress. The early cracking of the ceramic layer occurs near the top of the bulge. One bulge near the peak or valley of the interface leads to a coating life reduction of about 75% compared with that without a bulge. The increase in the number of bulges further decreases the coating life, which is independent of the bulge location. The results in this work indicate that a smooth TC/BC interface obtained by some possible surface treatments may be an optional scenario for improving coating life.