In vitro remineralization of hybrid layers using biomimetic analogs

Resin-dentin bond degradation is a major cause of restoration failures. The major aim of the current study was to evaluate the impact of a remineralization medium on collagen matrices of hybrid layers of three different adhesive resins using nanotechnology methods. Coronal dentin surfaces were prepared from freshly extracted premolars and bonded to composite resin using three adhesive resins (FluoroBond II, Xeno-III-Bond, and iBond). From each tooth, two central slabs were selected for the study. The slabs used as controls were immersed in a simulated body fluid (SBF). The experimental slabs were immersed in a Portland cement-based remineralization medium that contained two biomimetic analogs (biomineralization medium (BRM)). Eight slabs per group were retrieved after 1, 2, 3, and 4 months, respectively and immersed in Rhodamine B for 24 h. Confocal laser scanning microscopy was used to evaluate the permeability of hybrid layers to Rhodamine B. Data were analyzed by analysis of variance (ANOVA) and Tukey’s honest significant difference (HSD) tests. After four months, all BRM specimens exhibited a significantly smaller fluorescent area than SBF specimens, indicating a remineralization of the hybrid layer (P≤0.05). A clinically applicable biomimetic remineralization delivery system could potentially slow down bond degradation.     

虚拟现实系统中人机交互感官机理研究

探讨人机交互机理中感知系统模型和行为系统模型的基本原理与特点，总结出深入研究人机交互机理是实现虚拟现实人机交互的基础。同时指出人机交互感官机理研究有待进一步加强的方面。     

Differences in pedalling technique between road cyclists of different competitive levels

The purpose of this study was to compare the pedalling technique in road cyclists of different competitive levels. Eleven professional, thirteen elite and fourteen club cyclists were assessed at the beginning of their competition season. Cyclists’ anthropometric characteristics and bike measurements were recorded. Three sets of pedalling (200, 250 and 300 W) on a cycle ergometer that simulated their habitual cycling posture were performed at a constant cadence (~90 rpm), while kinetic and kinematic variables were registered. The results showed no differences on the main anthropometric variables and bike measurements. Professional cyclists obtained higher positive impulse proportion (1.5–3.3% and P < 0.05), mainly due to a lower resistive torque during the upstroke (15.4–28.7% and P < 0.05). They also showed a higher ankle range of movement (ROM, 1.1–4.0° and P < 0.05). Significant correlations (P < 0.05) were found between the cyclists’ body mass and the kinetic variables of pedalling: positive impulse proportion (r = ?0.59 to ?0.61), minimum (r = ?0.59 to ?0.63) and maximum torques (r = 0.35–0.47). In conclusion, professional cyclists had better pedalling technique than elite and club cyclists, because they opted for enhancing pulling force at the recovery phase to sustain the same power output. This technique depended on cycling experience and level of expertise.     

支付股息欧式看涨期权的两种定价方法

根据投资组合理论,本文建立了支付股息欧式看涨期权的价格模型,并在此基础上研究了两种定价方法。     

浅谈实践环节在教学过程中的重要性

从实践教学和理论教学的特点出发，通过分析两者间的关系，论述了实践教学在教学改革过程中的重要性，并指出教学过程中两者应相辅相成、取长补短。     

高校自媒体“中央厨房”模式建设研究

高校自媒体向融媒体转型,是当今互联网环境下的重大举措。构建“中央厨房”模式是融媒体建设的重点,其对“围绕中心、服务大局,确保新闻宣传、舆论引导目标与学校发展目标、中心工作同向同行”有着重要意义。高校“中央厨房”的建构过程中有其特有的时代使命和组织形式。鉴于此,提出高校“中央厨房”应以“提升新闻舆论传播力和影响力”为中心的建设四步走策略,以促进高校立体式宣传模式的全面建立。     

基于Pro/E的直齿锥齿轮Program参数化造型

介绍Pro/Engineer的Program参数化造型方法及其程序结构,并且以直齿锥齿轮为实例,详细地介绍Program参数化造型的实现过程。为同类产品实现参数化造型,减少重复劳动,提高设计效率提供一种适用、有效的方法。     

由“河堤决口了,洪水冲过来了”说开去

复句中的语义关系既是事物之间客观联系的反映,又是人们主观视角的反映。在事物之间的客观联系保持固定的情况下,人们的主观视角会随着认知需求的变化而变化。表现在复句中,则是适时添加复句关系词。并列范畴转化为因果范畴是人的特定视角的转化,这需要一定的客观条件,同时又必须有一定的认知作为前提。     

论《贞观政要》中唐太宗的人才思想

唐太宗的人才思想涉及到人才学的诸多方面,是一个完整的体系.研究唐太宗的人才思想,对全面建设小康社会具有重要的借鉴意义.     

热喷涂机器人离线编程

在介绍热喷涂机器人2种编程方法和机器人离线编程的基础上,概括叙述了从机器人离线编程阶段到应用于实际车间机器人喷涂的整个步骤;针对实际机器人喷涂过程中出现的机器人与车间里的设备碰撞的问题,提出了较好的解决方案,即建立虚拟车间;详细介绍了热喷涂虚拟车间的设计、建立步骤。实际的应用效果表明,虚拟车间的建立,避免了重大事故的发生,缩短了离线编程的时间,提高了生产率。