Microstructure Evolution and Improved Permeability of Ceramic Waste-Based Bricks

The resource and large-scale utilization of waste ceramic materials, magnesium slag, and coal gangue are one of the important ways for the sustainable development in metallurgy, coal, and other related enterprises. In this paper, waste ceramic materials were used as aggregates; coal gangue and magnesium slag were used as mixed binder; and the all solid-waste-based permeable bricks with excellent performance were prepared by forming pressure at 5 MPa. The mechanical properties and water permeability of the all-solid-waste-based permeable bricks were evaluated. The results proved that the porous channel of permeable brick is mainly composed of waste ceramic materials with a particle size of 2–3 mm. Pore structures below 200 μm were mainly composed of fine aggregate and mixed binder. Using 60% coarse aggregate, 20% fine aggregate, 10% coal gangue, and 10% magnesium slag as raw materials, the all-solid-waste-based permeable bricks were obtained by pressing at 6 MPa and sintering at 1200 °C, which exhibited the best performance, and its water permeability, compressive strength, and apparent porosity were 1.56 × 10⁻² cm/s, 35.45 MPa, and 13.15%, respectively. Excellent water permeability, compressive strength, and apparent porosity of the all solid-waste-based permeable bricks were ascribed to the high content of connecting open pores, and closely adhesive force were ascribed to the porous microstructure constructed by the grading of waste ceramic materials and the tight conjoined points of the liquid phases in coal gangue and magnesium slag at a high sintering temperature.     

石膏矫形治疗幼儿特发性脊柱侧弯的临床研究

目的介绍简易石膏床方法行石膏矫形治疗幼儿特发性脊柱侧弯,并进行效果评价。方法选取2014年9月至2016年9月于河北省儿童医院住院治疗的25例幼儿特发性脊柱侧弯病例作为研究对象,平均年龄29.7个月(17~53个月),其中男童10例,女童15例,共行石膏矫形105次。应用去旋转石膏矫形方法并结合我院实际情况采用简易石膏床对患儿进行石膏矫形,测量并记录石膏矫形前后脊柱正位X线片上Cobb角改变情况,并对所有患儿按照性别及年龄是否≤2岁进行分组分析。结果 25例患儿石膏矫形治疗前脊柱侧弯Cobb角平均角度为(39.1±9.1)°,经过第1次石膏矫形后平均角度为(22.3±5.0)°,末次随访时平均角度为(20.3±4.3)°。第1次石膏矫形后Cobb角与矫形前相比差异有统计学意义(t=8.825,P<0.05)。随访终点时Cobb角与矫形前相比差异有统计学意义(t=9.653,P<0.05)。不同性别分组随访终点时Cobb角矫正度数差异无统计学意义(t=0.070,P=0.945)。不同年龄分组随访终点时Cobb角矫正度数差异无统计学意义(t=-0.733,P=0.471)。结论我们采用的简易石膏床方法结合去旋转技术进行石膏矫形可以纠正幼儿特发性脊柱侧弯患儿的Cobb角,性别和年龄因素未对矫正效果产生影响。     

自制IPS-Empress2铸瓷快速包埋材料的膨胀特性研究

IPS—Empress2铸瓷是国内外广泛应用的全瓷修复系统。为取代昂贵的进口专用包埋材料，国内已自制出与之相配套的快速包埋材料。本文研究的是其最关键的膨胀特性。采用千分尺位移计和热机械分析仪，分别测量了进口专用快速包埋材料和自制快速包埋材料的凝固膨胀及热膨胀性能，进行了统计分析和比较。结果显示，进口专用快速包埋材料的凝固膨胀率、热膨胀率和总膨胀率分别为0．858％、1．11％和1．17％；自制包埋材料的上述指标分别为0．798％、1．09％和1．16％，三项指标均无统计学差异，表明自制快速包埋材料的膨胀性能指标接近IPS—Empress2专用快速包埋材料，能满足IPS—Empress2铸瓷精密铸造的要求。     

不同切端设计的上前牙瓷贴面受载能力的定量研究

目的 瓷贴面因美观、微创的特点在临床上广为应用,但其使用寿命和破坏载荷的相关数据目前尚不清楚.该研究通过体外实验测定不同材料、不同设计的上前牙瓷贴面可承受的最大应力载荷,为前牙瓷贴面修复提供基础数据.方法 160颗离体上中切牙,随机分为8组,分别按照对接、切端包绕设计行牙体预备,用铸造玻璃陶瓷和氧化锆陶瓷制作贴面,并粘接;在万能测试机上进行不同受力方向的最大载荷实验,考察修复体对载荷的承受能力.结果 以60°和125°方向加载时,铸造玻璃陶瓷贴面的对接设计对载荷的承受能力均高于切端包绕设计,而切端包绕设计更利于氧化锆瓷贴面对载荷应力的分布.在以60°方向加载时,对于切断包绕设计,氧化锆陶瓷对载荷的承受能力明显优于铸造玻璃陶瓷,但对于对接设计,二者间并无明显差异.以125°方向加载时,在同种设计中,无论是切端包绕设计或对接设计,氧化锆陶瓷可承受的最大应力载荷均高于铸造玻璃陶瓷.结论 切端包绕设计的应力抵抗优于切端对接设计;氧化锆贴面目前存在粘接困难,但其破坏强度明显优于铸造玻璃陶瓷,有较好的潜在应用价值.     

Metallurgical and interfacial characterization of PFM Co–Cr dental alloys fabricated via casting,milling or selective laser melting

Objectives

Bulk and interfacial characterization of porcelain fused to metal (PFM) Co–Cr dental alloys fabricated via conventional casting, milling and selective laser melting.

Methods

Three groups of metallic specimens made of PFM Co–Cr dental alloys were prepared using casting (CST), milling (MIL) and selective laser sintering (SLM). The porosity of the groups was evaluated using X-ray scans. The microstructures of the specimens were evaluated via SEM examination, EDX and XRD analysis. Vickers hardness testing was utilized to measure the hardness of the specimens. Interfacial characterization was conducted on the porcelain-covered specimens from each group to test the elemental distribution with and without the application of INmetalbond. The elemental distribution of the probed elements was assessed using EDX line profile analysis. Hardness results were statistically analyzed using one-way ANOVA and Holm–Sidak's method (α = 0.05).

Results

X-ray radiography revealed the presence of porosity only in the CST group. Different microstructures were identified among the groups. Together with the γ phase matrix, a second phase, believed to be the Co₃Mo phase, was also observed by SEM and subsequent XRD analysis. Cr₇C₃ and Cr₂₃C₆ carbides were also identified via XRD analysis in the CST and MIL groups. The hardness values were 320 ± 12 HV, 297 ± 5 HV and 371 ± 10 HV, and statistically significant differences were evident among the groups.

Significance

The microstructure and hardness of PFM Co–Cr dental alloys are dependent on the manufacturing technique employed. Given the differences in microstructural and hardness properties among the tested groups, further differences in their clinical behavior are anticipated.     

不同设计类型的IPS Empress铸瓷贴面前牙美学修复的疗效观察

目的：通过比较研究不同设计类型的IPS?Empress铸瓷贴面在前牙美学修复中的临床疗效,探讨铸瓷贴面不同设计类型对瓷贴面成功率的影响。方法分别采用唇面覆盖型（Ⅰ型）、唇切缘覆盖型（L型）和唇切邻面覆盖型（U型）3种类型的贴面修复方法,对41例患者共计124颗患牙行铸瓷贴面修复,于修复后1周、6个月,12个月复诊观察修复体保存完整度、颜色匹配和边缘适合性等评价指标,评估其临床疗效。?结果???Ⅰ型贴面在第12个月时有1例在切端出现微小间歇;L型贴面在第6个月时出现2例脱落,第12个月时又出现1例因咬硬物脱落;U型贴面在第6个月时有1例出现边缘微小缝隙。3种类型的贴面在各随访时间段的成功率比较无明显差异。结论3种类型的铸瓷贴面均能取得较好的临床修复效果。     

菟丝子多糖复合羟基磷灰石局部植入对兔骨缺损修复的影响

目的：研究菟丝子多糖复合羟基磷灰石在促进兔骨缺损修复中的价值。方法：日本大耳白兔76只,随机分为实验组Ⅰ、实验组Ⅱ和模型组。行桡骨缺损造模后,实验组Ⅰ在缺损处植入菟丝子多糖-羟基磷灰石复合物,实验组Ⅱ在缺损处植入骨形态发生蛋白-羟基磷灰石复合物,模型组只造模不植入,分别在术后2、4、8周对实验组Ⅰ、实验组Ⅱ和模型组行抗折力学测试及骨痂重量检测。结果：术后4、8周,实验组Ⅰ与实验组Ⅱ之间的抗折力学测试结果无差异（P〉0.05）;术后2、4、8周,实验组Ⅰ与实验组Ⅱ之间的骨痂重量无显著性差异（P〉0.05）;术后4、8周,实验组Ⅰ、实验组Ⅱ的骨痂重量均大于同期实验组Ⅱ（P〉0.01,P〉0.05）。结论：菟丝子多糖复合羟基磷灰石局部植入能促进兔桡骨缺损修复。     

羟基磷灰石纳米粒子对肝癌H22小鼠肿瘤细胞凋亡的研究

目的通过不同浓度的羟基磷灰石(HAP)纳米粒子作用于肝癌H22小鼠肿瘤细胞,研究其对肿瘤细胞凋亡的影响。方法100只肝癌H22小鼠随即分组并连续服用不同剂量的HAP纳米粒子,11d后处死小鼠,计算抑瘤率和细胞凋亡率,评价不同剂量的HAP纳米粒子与H22小鼠肿瘤细胞生长的关系。结果肝癌H22小鼠肿瘤细胞对纳米羟基磷灰石(HAP)较敏感,能明显延长小鼠生存期,高剂量组与丝裂霉素结果相近(P>0.05)。实验后小鼠体重没有明显下降,抑瘤率和细胞的凋亡率随浓度升高而增大,呈明显的剂量依赖性(P<0.01)。结论不同浓度的羟基磷灰石(HAP)纳米粒子能够抑制H22肿瘤细胞的增殖,诱导肿瘤细胞的凋亡,并呈剂量依赖性。