Mutations in the N-terminal globular domain of the type X collagen gene (COL10A1) in patients with Schmid metaphyseal chondrodysplasia

STATEMENT OF PROBLEM: Improved dental stone has been widely used for producing dies for the fabrication of restorations with the lost-wax technique. Improved dental stone is used for several reasons, but it is selected most often because of its reasonable cost, ease of use, and ability to produce consistent results. PURPOSE: This study evaluated the ability of an epoxy resin die material and a type IV dental stone to dimensionally reproduce a custom-fabricated metal die. MATERIAL AND METHODS: Dies were fabricated and measurements were made from three reference lines. Measurements were repeated three times for the master die and for the specimen dies. A mean measurement and percent relative change for each dimension was calculated. RESULTS: A significant difference in the relative change for die height was found between the groups studied (p < 0.003). CONCLUSIONS: This epoxy die system will provide a degree of dimensional accuracy comparable to gypsum when used with addition silicone impression material.     

高铝微珠/环氧树脂复合材料冲蚀磨损特性

采用从高铝粉煤灰中提取的空心微珠为填料制备了高铝微珠/环氧树脂复合材料,并研究了复合材料的冲击强度及其冲蚀磨损特性.从冲蚀磨损机理、耐磨性能以及冲击性能方面分析,确定聚酰胺650是环氧树脂比较理想的固化剂.硅烷偶联剂改善了空心微珠与环氧树脂基体的相容性,有效地提高了环氧树脂的耐冲蚀磨损性能.当空心微珠的加入量较少时,复合材料的冲击强度及耐冲蚀磨损性能并没有得到明显改善;当空心微珠质量分数达到3%时,复合材料的冲击强度达到最大值,耐冲蚀磨损性能也有明显的提高,而在空心微珠质量分数为4%时复合材料的耐冲蚀磨损性能最佳,从而最终确定高铝粉煤灰空心微珠合适的填充量为3%～4%.      

纳米SiO2改性环氧树脂增强抛光磨料性能的研究

研究了用纳米SiO2改性的环氧树脂作为结合剂对抛光磨料力学性能的影响.考察纳米SiO2的掺量、固化温度和分散时间3个影响因素,确定每个单因素试验的水平范围,然后采用正交试验来确定改性后环氧树脂制备抛光磨料的适宜条件.结果表明,纳米SiO2颗粒与有机高分子产生接枝和键合作用,使材料韧性增加,经过纳米SiO2改性后的环氧树脂作为磨料结合剂制成的抛光磨料试块,其耐磨性和硬度均有所提高.正交试验确定的制备抛光磨料试验条件是:固化温度60℃,分散时间60 min,纳米SiO2的掺量3%.     

Accuracy, detail reproduction, and hardness of gypsum casts produced from silicone impressions treated with glow discharge

Plasma treatment has been reported to improve the wettability of silicone impression materials. This study investigated whether plasma treatment of silicone impressions influenced the linear dimensional accuracy, detail reproducibility, and surface hardness of models produced from a type IV dental die stone. Five silicone impressions materials were used in this study. Linear dimensional accuracy and detail reproduction were tested according to ISO standards. Surface hardness was evaluated with a Vickers hardness test. The results indicated that plasma-treated impressions from Xantopren and Provil silicone impression materials had significantly smaller dimensional change than their respective controls, and the other materials were not influenced. The detail reproduction was superior in casts produced from plasma-treated impressions from President silicone. Surface hardness was not influenced by the treatment. Plasma treatment of silicone impressions has no negative influence on the tested physical properties of die stone models.     

环氧树脂粘结剂提高复合脱氧剂落下强度的试验及应用

针对当前洁净钢用Al-CaO复合脱氧剂从10 m高料仓落下使用过程中易粉碎导致使用率低,成本增加,现场起尘污染等问题,研究了Al-CaO复合脱氧剂细粉中添加环氧树脂、改性淀粉等粘结剂,其含量（0~2.5%）,粘结剂固化温度（180~350℃）对复合脱氧剂落下强度的影响。结果表明,环氧树脂优于改性淀粉;随环氧树脂含量增加,复合脱氧剂落下强度增强,环氧树脂含量>2.0%后,粉碎率无明显变化;当环氧树脂加入量为2.0%,350℃固化时,复合脱氧剂粉碎率最低为17.5%。对RH精炼的EH40钢所用Al-CaO复合脱氧剂添加环氧树脂的应用表明,添加后明显提高复合脱氧剂的落下强度,降低了现场起尘污染和冶污成本。     

树脂黏度变化对RTM成型工艺的影响

采用黏度计测定不同初始温度下环氧树脂的黏度,通过拟合法建立环氧树脂的工程黏度模型.将黏度模型引入树脂传递模塑(resin transfer molding,RTM)成型树脂流动模拟中,结合PAM-RTM软件模拟不同初始温度下树脂的填充过程,讨论树脂黏度变化对RTM成型过程树脂流动行为的影响.结果表明,随着树脂初始温度的上升,填充时间先降后升,在初始温度为40℃时填充时间最短.树脂黏度变化对大型结构件RTM成型影响显著.      

Antigen detection on resin sections and methods for improving the immunogold labeling by manipulating the resin

Considering the importance of immunolocalization of cellular substances combined with good ultrastructure and ease of use, this review is focused on the use of resin and the possibilities of manipulating the resin before and after embedding in order to improve the immunolabeling of resin sections for electron microscopy. The qualities of acrylic resins and conventional epoxy resin for immunoelectron microscopy are discussed. Acrylic sections are usually more suited for immunoelectron microscopy than conventional epoxy sections. Different etching procedures (sodium ethoxide or sodium metaperiodate) may be applied to conventional epoxy sections to enhance the yield of immunolabeling. Lately, a method which does not involve any kind of etching has been developed for enhancing the immunogold labeling of epoxy sections up to about 8 times. This method involves increased concentration of accelerator in the epoxy resin mixture when processing the tissue. The ultrastructural preservation of the tissue is important in immunoelectron microscopical procedures, and not only the intensity of the immunolabeling; in this respect no resin may compete with the widely used epoxy resins.     

Chairside-fabricated indirect resin restorations: a new articulated technique

A case report of a chairside-fabricated indirect resin composite restoration is used to introduce a modification to a newly released one-appointment resin inlay-onlay technique. Fast-setting poly(vinyl siloxane) die material accommodates an articulated working cast within 10 minutes. The technique allows the economical construction of large, occlusal, load-bearing, extracoronal resin composite restorations. The guarded prognosis associated with extensive posterior resin composite restorations is acknowledged; nevertheless this technique remains a realistic option for those financially compromised patients who request tooth-colored restorations.     

Purpurediolin and purpurenin, two new cytotoxic adjacent bis-tetrahydrofuran annonaceous acetogenins from the seeds of Annona purpurea

PURPOSE: This study investigated the different effects of quantitative percentages of glass fiber intensity on the transverse strength, maximum deformation, and the modulus of elasticity of acrylic resin. MATERIALS AND METHODS: Fifty-four specimens were formed in a specially designed mold to produce identical specimens in accordance with the manufacturer's recommendations. Six percentages of glass fiber reinforcement in loose random form were studied. Each glass fiber treatment percentage (0%, 1%, 2%, 5%, 10%, 15%) was related to the total powder/liquid mass. RESULTS: The results indicated that 1% glass fiber treatment enhanced the transverse strength of the tested specimen. Maximum deformation at failure in the tested treatment groups was found to be different. The interaction of glass fiber concentration on fracture strength and deformation was significant (p < 0.0001). CONCLUSION: The 1% glass fiber concentration was found to give the best fracture strength and deformation results. Significantly higher glass fiber percentages was found to weaken the resin.     

Behavior of FRP-Retrofitted Joints Built with Plain Bars and Low-Strength Concrete

Two series of tests on eight full-scale exterior beam-column joint subassemblages built with plain bars and low-strength concrete were conducted. No transverse reinforcement was present in the joint cores. In the first series of tests, which included three specimens, the behavior of joints before fiber-reinforced polymer (FRP) retrofitting was investigated. In the second series, which included five specimens, the behavior of the FRP-retrofitted joints was investigated. The six specimens consisted of a column, an in-plane beam, a transverse beam, and a slab part, and two specimens were plane members without transverse beams and slabs. The utilized retrofitting scheme is easily applicable for actual exterior beam-column joints, even in the presence of a transverse beam and a slab. Two types of strength limitation were observed for specimens in the first series. The strength of the specimen with beam longitudinal bars sufficiently anchored to the joint core was limited by the shear strength of the joint. The strengths of the other two specimens were limited by the slip of the beams’ longitudinal bars at their anchorages. In the second series of tests, significantly better performance was obtained both in terms of shear strength and ductility, provided that the slip of the beam bars was prevented. Furthermore, by using a simple theoretical algorithm based on truss analogy, the strength and deformability characteristics of the tested reference and FRP-retrofitted joints are predicted with reasonable accuracy. The same algorithm is used for predicting the joint shear strength of specimens tested by other researchers, and satisfactory agreement is obtained between the predictions and test results.     

Effect of etchant, etching period, and silane priming on bond strength to porcelain of composite resin

The purpose of this study was to evaluate the effect of etching and silane priming on bond strength to a feldspathic porcelain (VMK 68) of a composite resin (Clearfil APX). Two hydrofluoric acid etchants (2.5% and 5%) and seven different etching times (0, 30, 60, 90, 120, 150, and 180 seconds) were used to etch the porcelain specimens respectively. A self-curing bonding agent containing a silane coupler (Clearfil Porcelain Bond) was used on both etched and unetched porcelain surfaces. Etched relief patterns were observed by means of a scanning electron microscope, and the bond strengths between the photocured composite resin and the porcelain were determined. Scanning electron micrographs revealed complicated etching patterns with increased etching time periods. Shear testing results showed that the bond strength to the unetched porcelain of the composite resin was very low, and that etching periods for more than 30 seconds effectively enhanced the bond strength. Of the two etching agents applied to the unsilanated porcelain, the buffered 2.5% etchant produced higher bond strengths than the 5% etchant for all etching time periods except for 180 seconds. Silane priming was effective and critical for improving bond strength to the porcelain. Application of the silane bonding agent to the porcelain after hydrofluoric acid etching appeared to be suitable for achieving consistent bonding between the composite resin and the porcelain.     

Breeding of Philander frenata (Didelphimorphia, Didelphidae) in captivity

STATEMENT OF PROBLEM: Because water sorption of autopolymerizing acrylic reline resins is accompanied by volumetric change, it is a physical property of importance. As residual monomer leaches into the oral fluids and causes tissue irritation, low solubility of these resins is desired. Another requirement is a satisfactory bond between the autopolymerizing acrylic resins and the denture base acrylic resin. PURPOSE: This study compared the water sorption, solubility, and the transverse bond strength of 2 autopolymerizing acrylic resins (Duraliner II and Kooliner) and 1 heat-polymerizing acrylic resin (Lucitone 550). MATERIAL AND METHODS: The water sorption and solubility test was performed as per International Standards Organization Specification No. 1567 for denture base polymers. Bond strengths between the autopolymerizing acrylic resins and the heat-polymerizing acrylic resin were determine with a 3-point loading test made on specimens immersed in distilled water at 37 degrees C for 50 hours and for 30 days. Visual inspection determined whether failures were adhesive or cohesive. RESULTS: Duraliner II acrylic resin showed significantly lower water sorption than Kooliner and Lucitone 550 acrylic resins. No difference was noted in the solubility of all materials. Kooliner acrylic resin demonstrated significantly lower transverse bond strength to denture base acrylic resin and failed adhesively. The failures seen with Duraliner II acrylic resin were primarily cohesive in nature. CONCLUSIONS: Autopolymerizing acrylic reline resins met water sorption and solubility requirements. However, Kooliner acrylic resin demonstrated significantly lower bond strength to denture base acrylic resin.     

Respiratory effects of occupational exposure to an epoxy resin system

A standardized respiratory questionnaire and pulmonary function tests were used to examine thirty-four employees of a snow-ski manufacturing plant, including twenty-five workers who were exposed to an epoxy resin system containing the amine hardener 3-dimethylamino propylamine (3-DMAPA). Maximum expiratory flow-volume curves were obtained on Monday and Thursday, before and after each shift, and FVC, FEV1.0, MEF50%, and MEF25% were caculated. Environmental measurements of the total amine levels were found to range from 0.41 to 1.38 ppm. The group with the greatest exposure (0.55-1.38 ppm) showed significant decreases in lung function over Monday and over the week. Although all employees in this group showed decreases in pulmonary function, acute changes were greater in present cigarette smokers and in subjects who reported respiratory symptoms upon exposure to the epoxy resin system. There was no evidence of permanent loss of lung function in subjects with either the highest or longest exposure.     

Study on preparation and properties of CeO2/epoxy resin composite coating on sintered NdFeB magnet

The CeO₂/epoxy resin composite coating was deposited on NdFeB substrate by cathode electrophoresis method for enhancing the anticorrosion and anti-wear performances. The morphologies and structures were characterized by a scanning electron microscope and an X-ray diffractometer. The micro hardness of the composite coating was evaluated by a microhardness tester. The corrosive behaviors of the coatings were studied by potentiodynamic polarization curve, electrochemical impedance spectroscopy and neutral salt spray tests. The concentration of CeO₂ nanoparticles (NPs) in the electrophoresis bath was optimized according to the coating structures and anticorrosion performances. The results show that CeO₂ NPs can enhance the microhardness of the composite coatings. Moreover, the nanoparticles disperse uniformly in the matrix when the concentration is lower than 30 g/L. The microhardness of CeO₂/epoxy resin (30 g/L) composite coating is about 63% higher than that of the blank epoxy resin coating. And the NSS time of the CeO₂/epoxy resin (30 g/L) composite coated sample can reach 1248 h. Meanwhile, the composite coatings possess no deteriorate influence on the magnetic properties of NdFeB substrates. The anticorrosion mechanisms of the composite coatings on the NdFeB substrate are deeply discussed.     

Effect of Contact Pressure on Bond Strength of Fiber-Reinforced Polymer to Concrete

In this technical note, the importance of contact pressure (0.03 N/mm2) during curing of adhesive between fiber reinforced polymer (FRP) and concrete is addressed. The shortcoming of fast-curing epoxy resin is pointed out. Different pressures and an ordinary epoxy resin were chosen to assess the effectiveness of contact pressure on FRP-to-concrete bond strength. The test results showed that the bond quality could be significantly improved by exerting a contact pressure ≥ 0.01 N/mm2. A simple and easy site-operation method for exerting contact pressure is also introduced.     

Strength of secondary-cured resin composite inlay repairs

A study was designed to simulate the repair of an indirect resin composite restoration with conventionally cured resin composite. Two-part specimens were prepared to test the diametral tensile strength of the repair interface between the base material of an indirectly cured resin composite (Herculite XRV) and repairs carried out with three directly cured materials (Herculite XRV, TPH, and Charisma). The repairs were carried out with and without use of the bonding resin for the repair material. The diametral tensile strengths of all repaired specimens were significantly less than those of bulk unrepaired specimens. There were no significant differences between the diametral tensile strengths of repaired blocks when the repair materials were used without bonding resin. The use of an intermediate layer of bonding resin significantly increased the bond strengths obtained when Herculite XRV and TPH were used for repair. There was no significant difference between the strength values of Herculite XRV and TPH, but Charisma exhibited the lowest strengths of repaired specimens.     

不同粘结剂对粘结NdFeB磁体磁性能和抗压强度的影响

本文采用三种不同环氧值的粘结剂制备了NdFeB粘结磁体,研究了粘结剂环氧值影响磁体磁性能及抗压强度的规律及其机理.实验结果表明,在优化的固化工艺条件下,采用环氧值适中的环氧树脂制备的磁体,具有较好的磁性能和抗压强度.     

Accelerated evolution and molecular surface of venom phospholipase A2 enzymes

The objective of this study was to determine the in vitro shear bond strength (in megapascals) and location of bond failure with two light-cured glass ionomer resin systems. One system was a hybrid glass ionomer cement with resin (GC Orthodontics, Aslip, Ill), and the other system a glass-filled resin system (Reliance Orthodontic Products, Inc, Itasca, Ill). These systems, Fuji Ortho LC (GC Orthodontics) and Ultra Band Lok (Reliance), respectively, were compared to a light-cured composite resin. Maxillary premolar brackets (n = 200) were bonded to the facial surface of human premolar teeth. The two glass ionomer resin systems were each evaluated by two protocols, one according to the manufacturers' direction plus a variation of their respective technique. The five distinct groups (n = 40) were stored in 37 degreesC distilled water for 30 days and subjected to thermocycling before shear bond strength testing. The findings indicated that large variations existed between the bond strengths of the materials tested. The laboratory shear bond strength of the glass-filled resin glass ionomer cement (Reliance), whether tested in a dry or moist field, was similar to the composite control with all of the previous materials being significantly (P <.01) higher than both the hybrid glass ionomer cement groups (Fuji Ortho LC). However, the hybrid glass ionomer cement with enamel conditioner demonstrated a clinically acceptable mean megapascal value. The Adhesive Remnant Index values ranged from 0.53 to 1.62. The hybrid glass ionomer cement without enamel conditioning recorded the lowest mean adhesive remnant index score and the lowest mean megapascal score. Although both products are glass ionomer resin systems, their individual chemistries vary; this affects their clinical performance. Clinically, it may be suggested that glass ionomers used in a dry field may be beneficial for orthodontic bonding, and that glass ionomer resin systems used in a moist environment need an enamel conditioner.     

Repair of 130-Year Old Masonry Bridge using High-Performance Cement Grout

The restoration of a masonry bridge pier built in 1887 was carried out using cement-based grout. Erosion of the pointing mortar of the pier core outer surface and cracks and voids in the pier core were encountered. This paper presents the methodology used to develop high-performance cement grouts for injection of deteriorated joints and cracks in the stone pier and describes the repair and monitoring operations. Portland and microfine cement-based grouts were optimized in the laboratory. An epoxy resin grout was used as a benchmark to compare the performance of the cement-based grouts. The effectiveness of the grout injection was assessed with core samples testing and nondestructive testing using the sonic tomography method to compare the quality of the medium before and after grouting. High penetrability of the grout was achieved for the high-performance mixtures. The use of high-early-strength cement with some silica fume replacement resulted in a relatively economical mixture exhibiting high performance. The results of this pilot study were later recommended for the rehabilitation of similar masonry piers.     

Enamel and dentine shear bond strength of two resin modified glass ionomers and two resin based adhesives

OBJECTIVES: The purpose of this in vitro study was to compare the shear bond strength to enamel and dentine of two resin modified glass ionomers (Fuji Bond L.C. and Vitrebond) and two resin based adhesives (Prime&Bond 2.1 and Scotchbond Multi-Purpose). METHODS: A total of 120 bond sites were prepared on either enamel (n = 60) or dentine (n = 60) on human molars by grinding the teeth flat with a 600 grit sandpaper. Each tooth substrate group was divided into four groups (n = 15) to match each material. Each of the four material systems was applied, according to the manufacturers instructions, to the bond sites. On top of the placed material, a microfilled composite was placed in a 2.5 mm diameter matrix and light-cured for 40 s. All specimens were thermocycled 500 times (5-55 degrees C). Shear bond strength values were determined 120 h after bonding using a Zwick testing machine. One-way ANOVA was used to determine whether significant differences (p < 0.05) existed among the material groups on enamel and dentine. Pairwise comparisons were used to determine significant differences (p < 0.05) among the four products. RESULTS: The ANOVA revealed strong significant differences on enamel (p = 0.0001) and dentine (p = 0.0172). The enamel bond strength values of the two resin based adhesives were significantly higher than one of the resin modified glass ionomers (Vitrebond), while the other resin modified glass ionomers did not differ from Scotchbond Multi-Purpose. On dentine, however, Vitrebond performed significantly better than the two resin based adhesives. CONCLUSIONS: The investigated resin modified glass ionomers bonded better to dentine surfaces than to enamel surfaces, while the investigated resin based adhesive systems bonded better to enamel than to dentine.