An apparent ensemble effect in the oxidative coupling of methane on hydroxyapatites with incorporated lead

The introduction of small quantities of lead into calcium hydroxyapatite catalysts produces marked increases in the selectivity to C₂₊ hydrocarbons, while the conversion of methane remains relatively constant. Small surface concentrations of lead are sufficient to achieve C₂₊ selectivities of 80 and 90%, with oxygen and nitrous oxide, respectively, in contrast with 18 and 46%, respectively, obtained in the absence of lead. Since surface concentration of lead species sufficient to stabilize pairs of methyl radicals in close proximity to each other would be expected to facilitate the formation of C₂ hydrocarbons, an ensemble effect appears to be extant.     

Synthesis and optical properties of Eu~(3+) ion doped nanocrystalline hydroxya patites embedded in PMMA matrix

Transparent,luminescent and functional nanocomposites demonstrate interesting optical and mechanical properties suitable for many optoelectronic applications.Transparent polymethyl methacrylate(PMMA) polymer nanocomposites modified with thenoyl-trifluoroacetonate(TAA) were fabricated by in situ polymerization and used as hosts for homogenous dispersion of 3 mol.% Eu3+:Ca10(PO4) 6(OH) 2(Eu3+:HA) hydroxyapatite ～20 nm large nanocrystals.The emission,excitation and transmission spectra as well as the fluorescence decay rates of bare Eu3+:HA nanocrystallites,Eu3+:HA embedded in the PMMA and and Eu:HA embedded in the PMMA/TTA nanocomposites were studied.The improvement of transparency was demonstrated with the addition of TTA as well as europium doped hy-droxyapatites in comparison to pure PMMA matrix.The Judd-Ofelt analysis of f-f transitions of Eu3+:HA nanocrystallites,the PMMA/Eu3+:HA and the PMMA+TTA/Eu3+:HA was performed to investigate the optical behavior of the polymeric composites.     

Bone Regeneration of a 3D-Printed Alloplastic and Particulate Xenogenic Graft with rhBMP-2

This study aimed to evaluate the bone regeneration capacity of a customized alloplastic material and xenograft with recombinant human bone morphogenetic protein-2 (rhBMP-2). We prepared hydroxyapatite (HA)/tricalcium phosphate (TCP) pure ceramic bone blocks made using a 3D printing system and added rhBMP-2 to both materials. In eight beagle dogs, a total of 32 defects were created on the lower jaws. The defective sites of the negative control group were left untreated (N group; 8 defects), and those in the positive control group were filled with particle-type Bio-Oss (P group; 12 defects). The defect sites in the experimental group were filled with 3D-printed synthetic bone blocks (3D group; 12 defects). Radiographic and histological evaluations were performed after healing periods of 6 and 12 weeks and showed no significant difference in new bone formation and total bone between the P and 3D groups. The 3D-printed custom HA/TCP graft with rhBMP-2 showed bone regeneration effects similar to that of particulate Bio-Oss with rhBMP-2. Through further study and development, the application of 3D-printed customized alloplastic grafts will be extended to various fields of bone regeneration.     

碳羟磷灰石吸附水溶性F^—的影响因素研究

驿羰羟磷灰石（CHAP）固定水溶性F^-的影响因素进行了较为系统的实验研究，结果表明：除F^-率与F^-的初始浓度，pH(温度（T≤0℃或T≥40℃）为负相关，与作用时间，CHAP用量，温度（0℃≤T≤40℃）显正相关。通过正交实验确定了最佳吸附条件，CHAP用量1.5g/L,pH值为7 ，体系温度20－40℃，作用时间为120min,F^-初始浓度小于300mg/L时。     

Ag-HA/TiO2抗菌剂的制备及在大黄鱼中的应用

为探究载银羟基磷灰石（AgHAp）/二氧化钛（Ag-HA/TiO ₂ ）抗菌剂在水产品中的应用,研究了Ag-HA/TiO ₂ 的结构表征。选取大肠杆菌和金黄色葡萄球菌为测试菌株,比较了AgHAp和Ag-HA/TiO ₂ 的抗菌性能,并初步判断Ag-HA/TiO ₂ 对水产品特定腐败菌荧光假单胞菌和腐败希瓦氏菌（SSOs）的抗菌率,在此基础上进行了实际应用。测试了抗菌液质量浓度和浸泡时间对大黄鱼的微生物和一级鲜肉标准的影响,结果表明：Ag-HA/TiO ₂ 负载二氧化钛、降低一半银质量分数后,结构晶形基本不变,Ag-HA/TiO ₂ 对大肠杆菌和金黄色葡萄球菌的抗菌率为100 %,比银质量分数为3.00%的AgHAp要好,且对该2种菌的最小抑菌质量浓度均为312.5 μg/mL;10 mg/mL Ag-HA/TiO ₂ 对SSOs在0.5 h时抑菌率分别为（97.58±3.43）%和100%,作用时间为1 h和1.5 h时均为100%;Ag-HA/TiO ₂ 浸泡液质量浓度越高或大黄鱼浸泡时间越长,对大黄鱼中细菌生长越有明显的抑制效果,且延长大黄鱼一级鲜肉标准的货架期。该研究结果证明,Ag-HA/TiO2抗菌具有高效性,有望成为一种理想的水产抗菌材料。     

羟基磷灰石（HAP）的制备方法及其研究进展

阐述了不同状态的羟基磷灰石（HAP）的制备方法及国内外进展,并提出了相应的设想与展望。     

Nanoporous surface of organofunctionalized hydroxyapatite fabricated from natural phosphate rock

Surface functionalized apatite nanoparticles were prepared by covalent grafting of nitrilotrismethylenetriphosphonates (NTP) into a mesoporous apatite layer, which has been converted from phosphate rock by dissolution-precipitation methods. BET measurements show that the specific surface area of the particles is between 88 and 193 m²/g, depending on the grafted phosphonate.     

Grain-oriented calcium hydroxyapatite ceramic and film prepared by magnetic alignment

Grain-oriented calcium hydroxyapatite (HA) ceramics are potential to enhance or select their bioactive properties. In the current work, highly a-axis oriented calcium HA bulk and thick film samples were prepared by a novel process combining magnetic alignment and polymerization techniques. The slurry containing 40 vol.% commercial HA powder, monomer, initiator and catalyst were poured into a rubber mold for bulk samples or drop-coated on Al₂O₃ substrate for films at first, and then moved them into a vertical 10 T magnetic field. The HA particles in the low viscosity slurry were aligned by magnetic force and then in situ locked via polymerization of the slurry. After sintering, the grain-oriented HA ceramic bulk and thick film samples with a-axis parallel to the magnetic field direction were obtained. Theoretically, the grain-orientation can be easily controlled by adjusting the magnetic field direction.