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Analysis of Pipeline Steel Corrosion Data From NBS (NIST) Studies Conducted Between 1922-1940 and Relevance to Pipeline Management. 美国国家统计局(NIST)在1922-1940年间进行的管道钢腐蚀数据分析及其与管道管理的相关性
IF 1.5 4区 工程技术 Pub Date : 2010-10-01 Print Date: 2010-09-01 DOI: 10.6028/jres.115.026
Richard E Ricker

Between 1911 and 1984, the National Bureau of Standards (NBS) conducted a large number of corrosion studies that included the measurement of corrosion damage to samples exposed to real-world environments. One of these studies was an investigation conducted between 1922 and 1940 into the corrosion of bare steel and wrought iron pipes buried underground at 47 different sites representing different soil types across the Unites States. At the start of this study, very little was known about the corrosion of ferrous alloys underground. The objectives of this study were to determine (i) if coatings would be required to prevent corrosion, and (ii) if soil properties could be used to predict corrosion and determine when coatings would be required. While this study determined very quickly that coatings would be required for some soils, it found that the results were so divergent that even generalities based on this data must be drawn with care. The investigators concluded that so many diverse factors influence corrosion rates underground that planning of proper tests and interpretation of the results were matters of considerable difficulty and that quantitative interpretations or extrapolations could be done "only in approximate fashion" and attempted only in the "restricted area" of the tests until more complete information is available. Following the passage of the Pipeline Safety Improvement Act in 2002 and at the urging of the pipeline industry, the Office of Pipeline Safety of the U.S. Department of Transportation approached the National Institute of Standards and Technology (NBS became NIST in 1988) and requested that the data from this study be reexamined to determine if the information handling and analysis capabilities of modern computers and software could enable the extraction of more meaningful information from these data. This report is a summary of the resulting investigations. The data from the original NBS studies were analyzed using a variety of commercially available software packages for statistical analysis. The emphasis was on identifying trends in the data that could be later exploited in the development of an empirical model for predicting the range of expected corrosion behavior for any given set of soil chemistry and conditions. A large number of issues were identified with this corrosion dataset, but given the limited knowledge of corrosion and statistical analysis at the time the study was conducted, these shortcomings are not surprising and many of these were recognized by the investigators before the study was concluded. However, it is important to keep in mind that complete soil data is provided for less than half of the sites in this study. In agreement with the initial study, it was concluded that any differences in the corrosion behavior of the alloys could not be resolved due to the scatter in the results from the environmental factors and no significant difference could be determined between alloys. Linear regressi

1911年至1984年间,美国国家标准局(NBS)进行了大量的腐蚀研究,包括测量暴露在真实环境中的样品的腐蚀损伤。其中一项研究是在1922年至1940年间进行的一项调查,调查了埋在美国47个不同地点的裸钢和锻铁管道的腐蚀情况,这些地点代表了不同的土壤类型。在这项研究开始时,人们对地下铁合金的腐蚀知之甚少。本研究的目的是确定(1)是否需要涂层来防止腐蚀,以及(2)是否可以使用土壤特性来预测腐蚀并确定何时需要涂层。虽然这项研究很快就确定了某些土壤需要涂层,但它发现结果是如此不同,以至于即使是基于这些数据的一般性结论也必须谨慎绘制。调查人员的结论是,影响地下腐蚀速率的因素多种多样,因此规划适当的试验和解释结果是相当困难的事情,定量的解释或推断只能"近似地"进行,而且只能在试验的"限定区域"进行,直到获得更完整的资料为止。随着2002年《管道安全改进法案》的通过,在管道行业的敦促下,美国运输部管道安全办公室联系了美国国家标准与技术研究所(NBS于1988年更名为NIST),要求对这项研究的数据进行重新检查,以确定现代计算机和软件的信息处理和分析能力是否能够从这些数据中提取出更有意义的信息。这份报告是对调查结果的总结。来自原始国家统计局研究的数据是使用各种商用软件包进行统计分析的。重点是确定数据中的趋势,这些趋势可用于开发经验模型,以预测任何给定土壤化学和条件下预期腐蚀行为的范围。通过该腐蚀数据集发现了大量问题,但考虑到研究进行时对腐蚀和统计分析的了解有限,这些缺点并不令人惊讶,其中许多问题在研究结束前就被研究人员发现了。然而,重要的是要记住,在这项研究中,只有不到一半的地点提供了完整的土壤数据。与最初的研究一致,由于环境因素对结果的分散,合金的腐蚀行为的任何差异都不能得到解决,并且合金之间没有明显的差异。腐蚀损伤测量值与实测土壤成分和性质的线性回归和曲线拟合发现了一些微弱的趋势。这些趋势通过多元回归得到改善,并利用不确定度估计建立了代表测试中样品性能的经验方程。这些腐蚀数据的经验模型的不确定性很大,并且超出这些实验的参数空间或暴露时间的外推将产生额外的不确定性。结论是,可以从这些数据中建立估计腐蚀损伤分布和速率的方程,但这些模型总是具有相对较大的不确定性,这将限制它们的效用。这些不确定性是由于埋葬地点的年、季节和样本位置变化导致测量结果的分散造成的。数据表明,更完整的土壤性质测量数据集反映了与统计设计实验样品直接接触的土壤和地下水的性质,将大大减少这种分散,并使预测更具代表性。
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引用次数: 46
Measuring Scale Errors in a Laser Tracker's Horizontal Angle Encoder Through Simple Length Measurement and Two-Face System Tests. 通过简单长度测量和双面系统测试测量激光跟踪仪水平角度编码器的尺度误差。
IF 1.5 4区 工程技术 Pub Date : 2010-10-01 Print Date: 2010-09-01 DOI: 10.6028/jres.115.022
B Muralikrishnan, C Blackburn, D Sawyer, S Phillips, R Bridges

We describe a method to estimate the scale errors in the horizontal angle encoder of a laser tracker in this paper. The method does not require expensive instrumentation such as a rotary stage or even a calibrated artifact. An uncalibrated but stable length is realized between two targets mounted on stands that are at tracker height. The tracker measures the distance between these two targets from different azimuthal positions (say, in intervals of 20° over 360°). Each target is measured in both front face and back face. Low order harmonic scale errors can be estimated from this data and may then be used to correct the encoder's error map to improve the tracker's angle measurement accuracy. We have demonstrated this for the second order harmonic in this paper. It is important to compensate for even order harmonics as their influence cannot be removed by averaging front face and back face measurements whereas odd orders can be removed by averaging. We tested six trackers from three different manufacturers. Two of those trackers are newer models introduced at the time of writing of this paper. For older trackers from two manufacturers, the length errors in a 7.75 m horizontal length placed 7 m away from a tracker were of the order of ± 65 μm before correcting the error map. They reduced to less than ± 25 μm after correcting the error map for second order scale errors. Newer trackers from the same manufacturers did not show this error. An older tracker from a third manufacturer also did not show this error.

本文描述了一种估计激光跟踪仪水平角编码器标度误差的方法。该方法不需要昂贵的仪器,如旋转台或甚至校准的工件。在两个安装在跟踪器高度上的目标之间实现了一个未校准但稳定的长度。跟踪器从不同的方位位置测量这两个目标之间的距离(例如,间隔为20°/ 360°)。每个目标的正面和背面都要测量。从这些数据可以估计出低阶谐波标度误差,然后可以用来校正编码器的误差图,以提高跟踪器的角度测量精度。我们已经在本文中对二阶谐波进行了证明。补偿偶阶谐波很重要,因为它们的影响不能通过平均正面和背面测量来消除,而奇阶谐波可以通过平均来消除。我们测试了来自三家不同制造商的六台追踪器。其中两个跟踪器是在撰写本文时引入的新模型。对于两家厂商生产的较老的跟踪器,在距跟踪器7 m处放置的7.75 m水平长度的长度误差在校正误差图之前为±65 μm。在修正二阶比例尺误差后,它们减小到±25 μm以下。来自同一制造商的较新的跟踪器没有显示此错误。来自第三家制造商的旧跟踪器也没有显示此错误。
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引用次数: 31
Fracture Toughness of Veneering Ceramics for Fused to Metal (PFM) and Zirconia Dental Restorative Materials. 金属熔覆陶瓷和氧化锆牙科修复材料的断裂韧性研究。
IF 1.5 4区 工程技术 Pub Date : 2010-09-01 Epub Date: 2010-10-01 DOI: 10.6028/jres.115.024
Janet B Quinn, George D Quinn, Veeraraghaven Sundar

Veneering ceramics designed to be used with modern zirconia framework restorations have been reported to fracture occasionally in vivo. The fracture toughness of such veneering ceramics was measured and compared to that of conventional feldspathic porcelain veneering ceramics for metal framework restorations. The fracture toughness of the leucite free veneer was measured to be 0.73 MPa m ± 0.02 MPa m, which is less than that for the porcelain fused to metal (PFM) veneering ceramic: 1.10 MPa ± 0.2 MPa. (Uncertainties are one standard deviation unless otherwise noted.) The surface crack in flexure (SCF) method was suitable for both materials, but precrack identification was difficult for the leucite containing feldspathic porcelain PFM veneer.

据报道,用于现代氧化锆框架修复的贴面陶瓷偶尔会在体内断裂。测量了这种贴面陶瓷的断裂韧性,并与传统的长石瓷贴面陶瓷的断裂韧性进行了比较。无白晶石贴面陶瓷的断裂韧性为0.73 MPa m±0.02 MPa m,低于烤瓷贴面陶瓷的断裂韧性1.10 MPa±0.2 MPa。(除非另有说明,不确定度为一个标准差。)表面弯曲裂纹(SCF)法适用于两种材料,但对含白石质长石瓷烤瓷单板的预裂纹识别较困难。
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引用次数: 48
Introduction to the Special Issue: Dental Chemistry of Calcium Phosphates. 特刊简介:磷酸钙的牙科化学。
IF 1.5 4区 工程技术 Pub Date : 2010-08-01 Print Date: 2010-07-01 DOI: 10.6028/jres.115.014
Clifton M Carey
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引用次数: 0
Properties of Injectable Apatite-Forming Premixed Cements. 可注射的磷灰石形成预混水泥的性能。
IF 1.5 4区 工程技术 Pub Date : 2010-07-01 Epub Date: 2010-08-01 DOI: 10.6028/jres.115.017
Yashushi Shimada, Laurence C Chow, Shozo Takagi, Junji Tagami

Previous studies reported premixed calcium phosphate cements (CPCs) that were stable in the package and form hydroxyapatite (HA) as the product after exposure to an aqueous environment. These cements had setting times of greater than 60 min, which are too long to be useful for some clinical applications. The present study investigated properties of fast-setting HA-forming premixed CPCs that initially consisted of two separate premixed pastes: (1) finely ground (1.0 μm in median size) dicalcium phosphate anhydrous (DCPA) mixed with an aqueous NaH(2)PO(4) solution, 1.5 mol/L or 3.0 mol/L in concentration, and (2) tetracalcium phosphate consisting of combinations of particles of two different size distributions, 5 μm (TTCP5) and 17 μm (TTCP17) in median size, mixed with glycerin. Equal volume of Pastes 1 and 2 were injected with the use of atwo-barrel syringe fitted with a static mixer into sample molds. The molar Ca/P ratio of combined paste was approximately 1.5. Cements were characterized in terms of setting time (Gilmore needle), diametral tensile strength (DTS), and phase composition (powder x-ray diffraction, XRD). Setting times were found to range from (4.3 ± 0.6 to 68 ± 3) min (mean ± sd; n = 3), and 1-d and 7-d DTS values were from (0.89 ± 0.08 to 2.44 ± 0.16) MPa (mean ± sd; n = 5). Both the NaH(2)PO(4) concentration and TTCP particle size distribution had significant (p < 0.01) effects on setting time and DTS. Powder XRD analysis showed that low crystallinity HA and unreacted DCPA were present in the 1-day specimens, and the extent of HA formation increased with increasing amount of TTCP5 in the TTCP paste. CONCLUSION: Injectable HA-forming premixed CPCs with setting times from 4 to 70 min can be prepared by using DCPA and TTCP as the ingredients. Compared to the conventional powder liquid cements, these premixed CPCs have the advantages of being easy to use and having a range of hardening times.

以前的研究报告称,预混合磷酸钙水门汀(CPC)在包装中很稳定,暴露于水性环境后会形成羟基磷灰石(HA)。这些水门汀的凝固时间超过 60 分钟,时间过长,无法用于某些临床应用。本研究调查了快速固化 HA 形成预混合 CPC 的特性,这些 CPC 最初由两种独立的预混合浆料组成:(1) 磨细(中值尺寸为 1.0 μm)的无水磷酸氢钙 (DCPA) 与 NaH(2)PO(4) 水溶液(1.5 摩尔/升或 3.0 摩尔/升)混合。5 mol/L 或 3.0 mol/L 浓度的无水磷酸二钙(DCPA)与 NaH(2)PO(4) 水溶液(浓度为 1.5 mol/L 或 3.0 mol/L)混合;(2) 磷酸四钙由中值尺寸为 5 μm (TTCP5) 和 17 μm (TTCP17)的两种不同尺寸分布的颗粒组合而成,并与甘油混合。使用装有静态混合器的双管注射器将等体积的浆料 1 和 2 注入样品模具。混合浆料的 Ca/P 摩尔比约为 1.5。对水泥的凝结时间(吉尔莫针)、直径拉伸强度(DTS)和相组成(粉末 X 射线衍射,XRD)进行了表征。凝结时间为(4.3 ± 0.6 至 68 ± 3)分钟(平均值 ± sd;n = 3),1 d 和 7 d DTS 值为(0.89 ± 0.08 至 2.44 ± 0.16)兆帕(平均值 ± sd;n = 5)。NaH(2)PO(4) 浓度和 TTCP 粒径分布对凝固时间和 DTS 均有显著影响(p < 0.01)。粉末 XRD 分析表明,1 天试样中存在低结晶度的 HA 和未反应的 DCPA,HA 的形成程度随 TTCP 浆料中 TTCP5 含量的增加而增加。结论:以 DCPA 和 TTCP 为成分可制备凝固时间为 4 至 70 分钟的可注射 HA 成型预混合 CPC。与传统的粉末液体水泥相比,这些预混合 CPC 具有使用方便、硬化时间范围广等优点。
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引用次数: 0
In Vitro and in Vivo Characteristics of Fluorapatite-Forming Calcium Phosphate Cements. 形成氟磷灰石的磷酸钙胶结物的体内外特性
IF 1.5 4区 工程技术 Pub Date : 2010-07-01 Epub Date: 2010-08-01 DOI: 10.6028/jres.115.020
Shozo Takagi, Stan Frukhtbeyn, Laurence C Chow, Akiyoshi Sugawara, Kenji Fujikawa, Hidehiro Ogata, Makoto Hayashi, Binnai Ogiso

This study reports for the first time in vitro and in vivo properties of fluorapatite (FA)-forming calcium phosphate cements (CPCs). The experimental cements contained from (0 to 3.1) mass % of F, corresponding to presence of FA at levels of approximately (0 to 87) mass %. The crystallinity of the apatitic cement product increased greatly with the FA content. When implanted subcutaneously in rats, the in vivo resorption rate decreased significantly with increasing FA content. The cement with the highest FA content was not resorbed in soft tissue, making it the first known biocompatible and bioinert CPC. These bioinert CPCs might be useful for applications where slow or no resorption of the implant is required to achieve the desired clinical outcome.

本研究首次报道了氟磷灰石(FA)形成的磷酸钙胶结物(CPCs)的体内外性能。实验水泥含有(0 ~ 3.1)质量%的F,对应于FA的含量约为(0 ~ 87)质量%。随着FA含量的增加,磷灰石水泥产品的结晶度大大提高。大鼠皮下注射后,体内吸收率随FA含量的增加而显著降低。FA含量最高的水泥不被软组织吸收,使其成为已知的第一个具有生物相容性和生物惰性的CPC。这些生物惰性cpc对于需要缓慢或不吸收植入物以达到预期临床效果的应用可能是有用的。
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引用次数: 14
Diffusion of Ions Between Two Solutions Saturated With Respect to Hydroxyapatite: A Possible Mechanism for Subsurface Demineralization of Teeth. 离子在两种饱和羟基磷灰石溶液之间的扩散:牙齿表面下脱矿的可能机制。
IF 1.5 4区 工程技术 Pub Date : 2010-07-01 Epub Date: 2010-08-01 DOI: 10.6028/jres.115.015
Laurence C Chow

Diffusion-controlled dissolution and precipitation reactions occur in many biological systems and some non-stirred in vitro systems. Previous studies have shown that differences in the diffusion rates of the ions involved in a dissolution/precipitation reaction can produce significant effects on the rate and course of the reaction. We report here results of a study that show inter-diffusion of ions between two solutions, both saturated with respect to hydroxyapatite but with dissimilar compositions, resulted in one solution becoming undersaturated and the other supersaturated. A model is proposed that may explain the formation of a mineral-dense layer in the caries process.

扩散控制的溶解和沉淀反应发生在许多生物系统和一些非搅拌的体外系统中。以往的研究表明,溶解/沉淀反应中离子扩散速率的差异会对反应的速率和过程产生显著影响。我们在这里报告了一项研究的结果,表明离子在两种溶液之间的相互扩散,两种溶液相对于羟基磷灰石都是饱和的,但具有不同的成分,导致一种溶液变得不饱和而另一种溶液变得过饱和。提出了一个可以解释龋蚀过程中致密矿物层形成的模型。
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引用次数: 1
Effects of Addition of Mannitol Crystals on the Porosity and Dissolution Rates of a Calcium Phosphate Cement. 甘露醇晶体的加入对磷酸钙水泥孔隙率和溶解速率的影响。
IF 1.5 4区 工程技术 Pub Date : 2010-07-01 Epub Date: 2010-08-01 DOI: 10.6028/jres.115.016
Debra Vazquez, Shozo Takagi, Stan Frukhtbeyn, Laurence C Chow

The bone defect repair functions of calcium phosphate cement (CPC) are related to its osteoconductivity and its gradual replacement by new bone. Adding mannitol to CPC may enhance its bone repair potential by increasing CPCs macroporosity and dissolution rate. The objective of the study was to assess microporosity and macroporosity and dissolution rates for CPC mixed with mannitol. Three groups of CPC discs were prepared by combining an equimolar mixture of tetracalcium phosphate and anhydrous dicalcium phosphate with (0 %, 10 %, or 50 %) mass fraction (hereafter expressed as mass %) of mannitol. Macroporosity and microporosity of the samples were calculated from volume and mass measurements of the discs. Discs were then placed in a pH 3.0 demineralizing solution simulating acidified physiological solution, and dissolution rates were measured by a previously described constant-composition titration method. Pure CPC exhibited no macropores and microporosity (mean ± s.d.; n = 5) of (46.8 ± 0.8) % volume fraction (hereafter expressed as vol %). Adding 10 mass % mannitol resulted in 15.6 ± 3.9 vol % macroporosity and 39.4 ± 1.8 vol % microporosity, and adding 50 mass % mannitol produced 54.7 ± 0.8 vol % macroporosity and 21.1 ± 0.4 vol % microporosity. The dissolution rates (mean ± s.d.; n = 5) of CPC with (0, 10, and 50) mass % mannitol incorporation were (30.6 ± 3.4, 44.8 ± 10.2, and 54.7 ± 3.6, respectively) μg · cm(-2) · min(-1), or (0.018 ± 0.002, 0.032 ± 0.007, and 0.072 ± 0.005, respectively) μL · cm(-2) · min(-1). Adding either 10 mass % or 50 mass % mannitol into CPC significantly (p < 0.05) increased CPC dissolution rates. Adding mannitol readily increased macroporosity and dissolution rate of CPC, which may enhance the capacity of CPC to be osteoconductive.

磷酸钙骨水泥(CPC)的骨缺损修复功能与其骨传导能力及其逐渐被新骨替代有关。甘露醇可通过增加CPCs的宏观孔隙度和溶出速率来增强CPCs的骨修复能力。该研究的目的是评估混合甘露醇的CPC的微孔隙率和宏观孔隙率以及溶出率。将磷酸四钙和无水磷酸二钙的等摩尔混合物与甘露醇(0%、10%、50%)质量分数(以下以质量%表示)混合制备三组CPC圆盘。通过测量圆盘的体积和质量,计算了试样的宏观孔隙度和微观孔隙度。然后将圆盘放入pH 3.0的模拟酸化生理溶液中,通过先前描述的恒成分滴定法测量溶解速率。纯CPC无宏观孔隙和微观孔隙(平均±s.d;N = 5)为(46.8±0.8)%体积分数(以下以vol %表示)。添加10质量%甘露醇的孔隙率为15.6±3.9 vol %,微孔隙率为39.4±1.8 vol %;添加50质量%甘露醇的孔隙率为54.7±0.8 vol %,微孔隙率为21.1±0.4 vol %。溶出率(平均±s.d;n = 5),甘露醇掺入(0、10、50)质量%的CPC分别为(30.6±3.4、44.8±10.2、54.7±3.6)μL·cm(-2)·min(-1)或(0.018±0.002、0.032±0.007、0.072±0.005)μL·cm(-2)·min(-1)。添加10%质量%和50%质量%的甘露醇可显著提高CPC的溶出率(p < 0.05)。甘露醇的加入增加了CPC的宏观孔隙率和溶解速率,从而增强了CPC的骨传导能力。
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引用次数: 8
In Vivo Characteristics of Premixed Calcium Phosphate Cements When Implanted in Subcutaneous Tissues and Periodontal Bone Defects. 植入皮下组织和牙周骨缺损处的预混合磷酸钙粘合剂的体内特性
IF 1.5 4区 工程技术 Pub Date : 2010-07-01 Epub Date: 2010-08-01 DOI: 10.6028/jres.115.021
Akiyoshi Sugawara, Kenji Fujikawa, Satoshi Hirayama, Shozo Takagi, Laurence C Chow

Previous studies showed that water-free, premixed calcium phosphate cements (Pre-CPCs) exhibited longer hardening times and lower strengths than conventional CPCs, but were stable in the package. The materials hardened only after being delivered to a wet environment and formed hydroxyapatite as the only product. Pre-CPCs also demonstrated good washout resistance and excellent biocompatibility when implanted in subcutaneous tissues in rats. The present study evaluated characteristics of Pre-CPCs when implanted in subcutaneous tissues (Study I) and used for repairing surgically created two-wall periodontal defects (Study II). Pre-CPC pastes were prepared by combining CPC powders that consisted of CPC-1: Ca(4)(PO(4))(2)O and CaHPO(4), CPC-2: α-Ca(3)(PO(4))(2) and CaCO(3) or CPC-3: DCPA and Ca(OH)(2) with a glycerol at powder-to-liquid mass ratios of 3.5, 2.5, and 2.5, respectively. In each cement mixture, the Ca to P molar ratio was 1.67. The glycerol contained Na(2)HPO(4) (30 mass %) and hydroxypropyl methylcellulose (0.55 %) to accelerate cement hardening and improve washout resistance, respectively. In Study I, the test materials were implanted subcutaneously in rats. Four weeks after the operation, the animals were sacrificed and histopathological observations were performed. The results showed that all of the implanted materials exhibited very slight or negligible inflammatory reactions in tissues contacted with the implants. In Study II, the mandibular premolar teeth of mature beagle dogs were extracted. One month later, two-wall periodontal bone defects were surgically created adjacent to the teeth of the mandibular bone. The defects were filled with the Pre-CPC pastes and the flaps replaced in the preoperative position. The dogs were sacrificed at 1, 3 and 6 months after surgery and sections of filled defects resected. Results showed that one month after surgery, the implanted Pre-CPC-1 paste was partially replaced by bone and was converted to bone at 6 months. The pockets filled with Pre-CPC-2 were completely covered by newly formed bone in 1 month. The Pre-CPC-2 was partially replaced by trabecular bone in 1 month and was completely replaced by bone in 6 months. Examination of 1 month and 3 month samples indicated that Pre-CPC-2 resorbed and was replaced by bone more rapidly than Pre-CPC 1. Both Pre-CPC pastes were highly osteoconductive. When implanted in periodontal defects, Pre-CPC-2 was replaced by bone more rapidly than Pre-CPC-1.

以前的研究表明,与传统的磷酸钙水门汀相比,无水预混磷酸钙水门汀(Pre-CPCs)的硬化时间更长,强度更低,但在包装中却很稳定。这些材料只有在进入潮湿环境后才会硬化,并形成羟基磷灰石作为唯一的产物。将 Pre-CPCs 植入大鼠皮下组织时,还表现出良好的耐冲刷性和出色的生物相容性。本研究评估了将 Pre-CPCs 植入皮下组织(研究 I)和用于修复手术造成的双壁牙周缺损(研究 II)时的特性。将由 CPC-1:Ca(4)(PO(4))(2)O 和 CaHPO(4)、CPC-2:α-Ca(3)(PO(4))(2) 和 CaCO(3) 或 CPC-3:DCPA 和 Ca(OH)(2)组成的 CPC 粉末与甘油混合,粉液质量比分别为 3.5、2.5 和 2.5,制备 Pre-CPC 浆料。在每种水泥混合物中,Ca 与 P 的摩尔比均为 1.67。甘油中含有 Na(2)HPO(4) (30 质量 %) 和羟丙基甲基纤维素 (0.55 %),分别用于加速水泥硬化和提高抗冲刷性。在研究 I 中,试验材料被植入大鼠皮下。手术四周后,动物被处死并进行组织病理学观察。结果显示,所有植入材料在与植入物接触的组织中都表现出非常轻微或可以忽略不计的炎症反应。在研究 II 中,成熟的小猎犬下颌前磨牙被拔除。一个月后,通过手术在下颌骨牙齿附近形成两壁牙周骨缺损。用 Pre-CPC 粘贴剂填充缺损,并在术前位置替换牙瓣。狗在术后 1、3 和 6 个月被处死,并切除已填充缺损的部分。结果显示,术后 1 个月,植入的 Pre-CPC-1 粘贴部分被骨取代,6 个月后转变为骨。用 Pre-CPC-2 填充的凹陷在 1 个月后完全被新形成的骨覆盖。1 个月后,Pre-CPC-2 部分被骨小梁取代,6 个月后完全被骨取代。对 1 个月和 3 个月样本的检查表明,Pre-CPC-2 比 Pre-CPC 1 更快吸收并被骨取代。当植入牙周缺损处时,Pre-CPC-2 比 Pre-CPC-1 更快地被骨取代。
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引用次数: 0
Preparation and Properties of Nanoparticles of Calcium Phosphates With Various Ca/P Ratios. 不同钙磷比磷酸钙纳米颗粒的制备及性能研究。
IF 1.5 4区 工程技术 Pub Date : 2010-07-01 Epub Date: 2010-08-01 DOI: 10.6028/jres.115.018
Limin Sun, Laurence C Chow, Stanislav A Frukhtbeyn, John E Bonevich

This study aimed at preparing and studying the properties of nanoparticles of calcium phosphate (nCaP) with Ca/P ratios ranging from 1.0 to 1.67 using a spray-drying technique. Micro-structural analyses suggested that the nCaPs with Ca/P ratios of 1.67 to 1.33 were nano-sized amorphous calcium phosphate (ACP) containing varying amounts of acid phosphate and carbonate. The nCaP with Ca/P ratio of 1 contained only nano-sized low crystalline dicalcium phosphate (DCP). BET measurements of the nCaPs showed specific surface areas of (12 ± 2 to 50 ± 1) m(2)/g, corresponding to estimated equivalent spherical diameters of (38 to 172) nm. However, dynamic light scattering measurements revealed much larger particles of (380 ± 49 to 768 ± 111) nm, owing to agglomeration of the smaller primary nano particles as revealed by Scanning Electron Microscopy (SEM). Thermodynamic solubility measurements showed that the nCaPs with Ca/P ratio of 1.33 - 1.67 all have similar solubility behavior. The materials were more soluble than the crystalline hydroxyapatite (HA) at pH greater than about 4.7, and more soluble than β-tricalcium phosphate (β-TCP), octacalcium phosphate (OCP) and DCP at pH above 5.5. Their solubility approached that of α-tricalcium phosphate (α-TCP) at about pH 7. These nCaPs, which cannot be readily prepared by other currently available methods for nanoparticle preparation, have potential biomedical applications.

本研究旨在利用喷雾干燥技术制备和研究Ca/P比值为1.0 ~ 1.67的磷酸钙纳米颗粒(nCaP)的性能。微观结构分析表明,Ca/P比值在1.67 ~ 1.33之间的ncap是含有不同量的酸性磷酸钙和碳酸盐的纳米无定形磷酸钙(ACP)。Ca/P比为1的nCaP只含有纳米级低晶磷酸二钙(DCP)。BET测量显示ncap的比表面积为(12±2至50±1)m(2)/g,对应于估计的等效球直径为(38至172)nm。然而,动态光散射测量显示,由于扫描电子显微镜(SEM)显示较小的初级纳米颗粒聚集,导致颗粒更大(380±49 ~ 768±111)nm。热力学溶解度测试表明,Ca/P比值为1.33 ~ 1.67的ncap具有相似的溶解度行为。在pH大于4.7左右时,材料的可溶性高于结晶羟基磷灰石(HA);在pH大于5.5时,材料的可溶性高于β-三磷酸钙(β-TCP)、八磷酸钙(OCP)和DCP。它们的溶解度接近于α-磷酸三钙(α-TCP)的溶解度。这些ncap目前无法通过其他可用的纳米颗粒制备方法制备,具有潜在的生物医学应用。
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引用次数: 104
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Journal of Research of the National Institute of Standards and Technology
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