中国食材分类方法浅析

物以类聚,按类划分物质是认识了解使用该物质的前题,通过对古代药物本草、食物本草的分类方法的演变分析,得出分类方法是伴随着药性、食性的发展而逐步形成发展起来的,同时分类方法又能促进人们对食性、药性的认识和利用。     

历史上有代表性的食疗典籍初探

目前专门研究分析食物类典籍著录内容及特点的文献鲜见,本文从食物食品的性能、分类、数量、著录方式及有关食养理论的角度对历史上有代表性的4部食疗典籍进行研究,由古至近作一对比阐述,旨在了解食疗的基础学科食疗本草的发展现状——有待于发展完善,为中国食材性能研究奠定基础。     

加强食材学研究完善中医食疗学理论体系

本文使用类比的方法,通过对中药学与中医学的辨证关系分析,目前中医食疗学理论体系的构架分析,提出以"方药共荣"思想加强中医食材学研究,促进完善中医食疗学理论体系。     

10种广东本地清热解毒中草药抗细菌内毒素作用实验研究

目的:探讨10种广东本地清热解毒中草药的抗细菌内毒素作用。方法:采用鲎试剂试管凝集反应进行体外抗内毒素实验。结果:所研究的10种广东本地清热解毒中草药,药液浓度为1.0g/mL时,10种中草药均有抗鲎试剂试管凝集反应,均具有抗细菌内毒素的作用;调整浓度为0.5g/mL时,除金扭扣、溪黄草外,其余中草药具有抗细菌内毒素作用;浓度为0.3g/mL时,除金扭扣、溪黄草、岗梅根外,其余中草药具有抗细菌内毒素作用;浓度为0.1g/mL时,田基黄、葫芦茶、救必应具有抗细菌内毒素作用,提示不同的药材存在抗细菌内毒素作用的差异。结论:广东10种本地清热解毒中草药有直接抗细菌内毒素的作用;其中田基黄、葫芦茶、救必应的抗内毒素作用最强、金扭扣、溪黄草的抗细菌内毒素作用较弱。     

我国民用药品器材国防动员的发展趋势探讨

本文结合我国的国情和军情,在国防动员及国防卫生动员研究的基础上,对我国尚属专项研究领域空白的民用药品器材动员进行归纳性的分析,总结其内涵、必要性以及特征,并对我国民用药品器材动员的未来发展提出自己的看法。     

药品集中招标采购价值的思考—基于新制度经济学理论的分析

集中招标采购是药品分散采购市场出现问题后的制度选择。在我国,药品集中招标采购仅仅被视为一种采购的手段,而忽略了其作为特殊市场的替代机制的本质。因此,从新制度经济学的角度去剖析药品集中招标采购制度,认识其制度内涵,对认清药品集中招标采购制度完善的方向具有一定的指导意义。     

Analysis of interfacial fracture in dental restorations

Objectives

To provide a brief summary of the background theory of interfacial fracture mechanics and develop an analytical framework that identifies the critical factors for the analysis of the initiation and propagation of adhesion failure in composite restorations.

Methods

A conceptual framework utilizing interfacial fracture mechanics and Toya's solution for a partially delaminated circular inclusion in an elastic matrix, which can be applied (with caution) to approximate polymer curing induced cracking about composite resins for class 1 cavity restorations.

Results

The findings indicate that: (1) most traditional shear tests are not appropriate for the analysis of the interfacial failure initiation; (2) material properties of the restorative and tooth material have a strong influence on the energy realize rate; (3) there is a strong size effect; and (4) interfacial failure once initiated is characterized by unstable propagation along the interface almost completely encircling the composite.

Significance

The work is important for the analysis of the reliability of composite class I restorations and provides an adequate interpretation of recent adhesion debonding experimental results utilizing tubular geometry of specimens. The approach clearly identifies the critical parameters including; curing strain, material modulii, size and interfacial strain energy release rate for reliable development of advanced restorative materials.     

Surface integrity of solvent-challenged ormocer-matrix composite

Objective

To investigate the surface integrity of solvent-challenged ormocer-matrix composites, photoactivated by different light exposure modes, through surface-hardness measurements at different periods of time; and to compare such behavior with dimethacrylate-based materials.

Methods

One hundred percent ormocer-based matrix (experimental ormocer (ORM)), a commercial mixed dimethacrylate-ormocer-based matrix (Admira (ADR)) and two commercial dimethacrylate-based matrix composites (experimental controls, (Grandio (GRD) and Premise (PRE)) were evaluated. Disk specimens (4 mm × 2 mm) were prepared from each material and light-activated using either a standard (S) or soft-start (SS) light exposure protocol with an LED-curing unit. Top, irradiated surface Knoop hardness (KHN) was measured within the following experimental groups (n = 5): Group 1: immediately after exposure; Group 2: after dry and dark storage, Group 3: after storage in distilled water, and Group 4: immersion in absolute ethanol. Hardness of Groups 2-4 were measured after 7 days storage. Immediate hardness values were submitted to Student's t-tests separately for each material. Hardness values after treatments were submitted to two-way ANOVA and Tukey's post hoc test to compare values among different storage media and light exposure mode protocols. Comparisons among materials were described using percentage of hardness change. Statistical testing was performed at a pre-set alpha of 0.05.

Results

Immediate hardness values were not affected by the light exposure mode, regardless of the material. In general, exposure mode did not significantly affect hardness after 7 days storage, regardless of storage media or material. After 7 days dry storage, hardness values increased for all materials relative to immediate testing, and decreased after water and ethanol storage, with ethanol showing the greatest effect. The experimental ormocer-based material had the lowest percentage hardness change and thus proved more resistant to solvent degradation than the other materials, regardless of the light exposure method.

Significance

Irradiated surface hardness values and surface integrity were unaffected by light exposure mode, regardless of the material tested. The experimental ormocer-based material presented the least change in hardness as a result of solvent challenge than any of the commercial products: ormocer or conventional resin-based, and thus showed better surface integrity.     

Scanning electron microscopic evaluation of the material interface of adjacent layers of dental materials

Objective

Many dental materials are used in contact with each other in sandwich techniques. Liners, bases and permanent restorative materials are placed adjacent to each other and allowed to set under the same conditions. The same applies for endodontic materials where irrigating solutions and root canal dressings come in contact with root canal obturating materials and root-end fillers. The aim of this research was to investigate the material interface of mineral trioxide aggregate (MTA) in contact with non-setting calcium hydroxide paste (CH), glass ionomer cement (GIC) and intermediate restorative material (IRM).

Methods

All materials were mixed according to manufacturer's instructions. Freshly mixed MTA (Dentsply) was placed in a plastic container and another dental material was compacted on it while still unset. These materials included GIC (Fuji IX), non-setting calcium hydroxide (Calasept) and IRM (Dentsply). The materials were allowed to set for 28 days at 37 °C and 100% humidity. The layered materials were sectioned longitudinally embedded in resin and polished to expose the interface between the two materials. Scanning electron microscopy (SEM) was performed of the interface and X-ray energy dispersive analysis (EDX) was conducted at 50 μm intervals to establish elements present at specific distances from the material interface.

Results

The calcium hydroxide paste did not affect the hydration of MTA. Migration of silicon, aluminum and bismuth from the MTA to the CH occurred. The GIC exhibited a high degree of micro-cracking and some porosity in the interfacial region. Strontium from the GIC was detected at 200 μm within the MTA. The zinc from the IRM cement was detected at 100 μm within the MTA. The zinc affected the hydration of the MTA leading to retardation of setting and increased porosity.

Conclusions

MTA interacts with other dental materials with resultant elemental migration in adjacent materials. Zinc oxide eugenol based cements should be avoided in the presence of MTA as zinc causes retardation of cement hydration with increased porosity. Glass ionomer cements absorb the water of hydration from the MTA also resulting in increased porosity and incomplete hydration of MTA.     

Changes in stress relaxation property and softness of soft denture lining materials after cyclic loading

Objectives

Soft denture lining materials show varied and changeable stress relaxation property and softness under cyclic loading conditions. The purpose of this study was to determine the changes in the stress relaxation property and the softness of commercial soft lining materials after cyclic loading.

Methods

One plasticized acrylic-based material (Coe Soft: COS) and two silicone-based materials (Mucosoft: MUS; Sofreliner S: SFL) were investigated. For each material, 10 cylinder-shaped specimens were subjected to 29 days of cyclic loading, 1800 times per day; other 10 unloaded specimens were used as control groups. Stress relaxation ratio and softness were measured after 1, 4, 8, 15, 22 and 29 days of cyclic loading or storage.

Results

During 29 day period, the stress relaxation ratios of the cyclic loaded and unloaded COS, MUS and SFL specimens were 28.5-31.6% and 30.9-32.6%, 6.4-15.1% and 1.8-15.4%, 14.0-38.2% and 19.8-40.6%, respectively. The softness values of the cyclic loaded and unloaded COS, MUS and SFL specimens were 42.6-60.6% and 56.4-61.8%, 47.6-52.5% and 46.9-51.5%, 56.6-58.4% and 58.0-65.1%, respectively. Based on repeated-measures, 3-way ANOVA, the stress relaxation ratio was influenced by the loaded or stored period and the type of material (p < 0.05), but not by the application of cyclic loading; the softness value was influenced by the loaded or stored period and the application of cyclic loading (p < 0.05), but not by the type of material.

Significance

Soft lining materials showed the loaded or stored period and the material type dependent stress relaxation properties regardless of the application of cyclic loading. Softness value was influenced by the loaded or stored period and the application of cyclic loading.