Color Stability of Dry Earth Pigmented Maxillofacial Silicone A-2186 Subjected to Microwave Energy Exposure

PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments.     

Evaluation of Mechanical Properties of ZY-1 Maxillofacial Prosthetic Materials

Objective Maxillofacial prosthetic materials are used to replace facial parts lost through disease or trauma. Silicone rubbers are the materials of choice. The silicone elastomer A-2186 is a widely used maxillofacial prosthetic material. It is a pourable two-component silicone rubber cured by a platinum catalyst. Used as a prosthetic material, A-2186 has short working time and good mechanical properties. The purpose of this study is to evaluate the physical properties of new prosthetic materials based on addition-type silicone elastomer （ZY-1）, and compared the mechanical properties with those of A-2186, Methods Hardness, tensile strength, ultimate elongation, tear strength and adhesive bonding strength of ZY-1 and A-2186 were compared. Statistical analyses were done using a two-way analysis of variance （ANOVA）. Results The hardness and ultimate elongation of ZY-1 is similar to A-2186. However, tensile strength, tear strength of ZY-1 were higher than those of A-2186. Conclusion ZY-1 addition-type silicone elastomer processed good mechanical properties for use as a maxillofacial prosthetic material.     

锐钛型TiO_2性能研究 Ⅱ.锐钛型TiO_2的光化学活性封闭及其表征

用水热法ＳｉＯ２致密包覆封闭锐钛型ＴｉＯ２表面的光化学活性点,以Ｃｒ２Ｏ２－７的还原反应考察包覆层的致密性及包覆效果。讨论了ＴｉＯ２浆液的浓度、温度、ｐＨ及保温熟化等反应条件对ＳｉＯ２致密包覆的影响。     

纳米银应用于软衬材料的抗菌性实验研究

目的评价热固化型硅橡胶软衬材料中加入纳米银颗粒后的抗菌效果及对软衬剂和基托树脂结合强度的影响。方法体外实验对比热固化型硅橡胶软衬剂lucisoft分别添加纳米银颗粒、制霉菌素、米康唑制成标准试件后1周、2周、3周通过培养方法监测软衬剂对白色念珠菌抗菌性及时相关系,用电子万能材料测试机检测添加纳米银颗粒后粘结强度的变化。结果热固化型硅橡胶软衬剂lucisoft加入纳米银前后抗菌效果有明显差异(P<0.01),抗菌性随时间无明显改变(P>0.05),加入制霉菌素,米康唑后抗菌效果有明显差异(P<0.01),但随时间变化抗菌性明显减低(P<0.01),软衬剂中加入纳米银前后结合强度无明显改变(P>0.05)。结论在热固化型橡胶软衬材料中加入纳米银颗粒后的抗菌性及时效明显提高,软衬剂和基托树脂粘结强度未受影响,提示热固化型硅橡胶软衬材料中加入纳米银颗粒可作为预防义齿性口炎的积极措施。     

[18F]Fluoride labelling of macromolecules in aqueous conditions: silicon and boroaryl‐based [18F]fluorine acceptors, [18F]FDG conjugation and Al18F chelation

[¹⁸F]Fluorination is usually carried out by nucleophilic substitution reactions entailing the use of stringent conditions. A number of novel techniques including silicon and boron‐based fluoride acceptor molecules, [¹⁸F]fluoro‐2‐deoxy‐ d ‐glucose and chelation of the Al¹⁸F complex have been employed recently to achieve [¹⁸F]radiolabelling of macromolecules. These approaches are reviewed herein. Copyright © 2012 John Wiley & Sons, Ltd.     

Large‐scale bone mineral histomorphometry – report of a simplified technique

Karantzoulis V, Liapi C & Papaggelopoulos P
(2012) Histopathology
Large‐scale bone mineral histomorphometry – report of a simplified technique Aims: The aim of this study was the development of a simplified technique for bone mineral histomorphology on large undecalcified bone samples. Established techniques, such as undecalcified bone thin sectioning, ultrathin grinding, surface‐stained block grinding and micro‐computerized tomography (CT), are expensive, time‐consuming and put very high demands on equipment, safety standards, personnel and laboratory facilities. Methods and results: The method is based on the surface‐stained block‐grinding principle; however, its novelty lies in the selection of user‐friendly, safe and low‐cost materials, equipment and digitization techniques. We describe in detail the relevant steps, as well as many practical tips for their successful implementation: accurate bone cutting in thin sections with a customized arrangement on a commercial bandsaw, defatting with sodium hypochlorite, embedding in epoxy resin blocks at room temperature, silicon carbide paper grinding, von Kossa staining, flatbed scanner digitization and image processing. Conclusion: We believe that the proposed methodology could contribute to the expansion of the study of bone tissue, as it enables the rapid examination of bone specimens on a large scale with minimal laboratory requirements and consumables costs.     

A Mechanochemical Approach to Porous Silicon Nanoparticles Fabrication

Porous silicon samples have been reduced in nanometric particles by a well known industrial mechanical process, the ball grinding in a planetary mill; the process has been extended to crystalline silicon for comparison purposes. The silicon nanoparticles have been studied by X-ray diffraction, infrared spectroscopy, gas porosimetry and transmission electron microscopy. We have estimated crystallites size from about 50 nm for silicon to 12 nm for porous silicon. The specific surface area of the powders analyzed ranges between 100 m²/g to 29 m²/g depending on the milling time, ranging from 1 to 20 h. Electron microscopy confirms the nanometric size of the particles and reveals a porous structure in the powders obtained by porous silicon samples which has been preserved by the fabrication conditions. Chemical functionalization during the milling process by a siloxane compound has also been demonstrated.     

Optimization of the defibrillation current density in the heart region by a two-layer segmented electrode

Transthoracic defibrillation is a procedure applying high intensity electrical current through the thorax region by electrodes, in order to simultaneously activate most of the myocardial cells, thus enforcing them to reinstate a normal rhythm. A solution is proposed for analysis and synthesis of the current density distribution field J in the heart region. In an attempt to reach uniform excitation of the greatest possible quantity of myocardial cells, a field image is searched for, with the J-vector uniformity distribution as a criterion. The finite element method and the method of approximating functions are used, as well as nonlinear programming. This approach resulted in designing a two-layer defibrillation electrode, with the layer applied to the thorax divided in three different resistivity regions.     

Exploitation of silicon medicinal chemistry in drug discovery

There remains considerable pressure on the pharmaceutical industry to increase productivity and reduce the attrition of drug candidates. Genomics, parallel chemistry and high-throughput biology have not yielded the anticipated benefits, resulting in a renewed focus on validated targets and an aim to generate drugs directed towards such targets, which have a clear advantage. One strategy to identify and develop best-in-class drugs is to apply a high degree of innovation in chemistry and apply this to targets from gene families that have been clinically validated as tractable and drugable. The application of organosilicon medicinal chemistry in the context of privileged structures to aid drug design and development is one such innovative approach that is reviewed in this paper.     

Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

In this study, silicon nitride (SiN_x) thin films were deposited on polyimide (PI) substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD) system. The gallium-doped zinc oxide (GZO) thin films were deposited on PI and SiN_x/PI substrates at room temperature (RT), 100 and 200 °C by radio frequency (RF) magnetron sputtering. The thicknesses of the GZO and SiN_x thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiN_x thin films were a working pressure of 800 × 10⁻³ Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH₄ = 20 sccm and NH₃ = 210 sccm, respectively. For the GZO/PI and GZO-SiN_x/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiN_x/PI substrates with thickness of ~000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si) thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiN_x/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiN_x/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiN_x/PI.