Effects of acidic calcium phosphate concentration on mechanical strength of porous calcite fabricated by bridging with dicalcium phosphate dihydrate

Porous calcium carbonate (CaCO₃) has attracted attention as an artificial bone substitute. We previously reported that interconnected porous calcite block can be fabricated when calcite granules are exposed to acidic calcium phosphate (ACaP) under loading conditions. Dicalcium phosphate dihydrate (DCPD) formed on the surface of the calcite granules caused bridging of the calcite granules with one another and formed an interconnected porous calcite block with DCPD. In this study, the effect of the ACaP concentration on the mechanical strength of the interconnected porous calcite was studied under loading conditions. When the ACaP concentration was increased, the amount of DCPD increased and the compressive strength of the porous calcite increased to approximately 2 MPa. The interconnected porous structure was maintained regardless of the ACaP concentration. No statistically significant difference was observed for the porosity, which was approximately 50%, based on the concentration of ACaP. Therefore, we concluded that the amount of precipitated DCPD can be regulated by the concentration of ACaP solution, and the mechanical strength of the porous calcite can be regulated by the amount of the precipitated DCPD.     

Interaction of the catalytic domain of inositol 1,4,5-trisphosphate 3-kinase A with inositol phosphate analogues

The levels of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] in the cytoplasm are tightly regulated by two enzymes, Ins(1,4,5)P3 3-kinase and type I Ins(1,4,5)P3 5-phosphatase. The catalytic domain of Ins(1,4,5)P3 3-kinase (isoenzymes A, B and C) is restricted to approximately 275 amino acids at the C-terminal end. We were interested in understanding the catalytic mechanism of this key family of enzymes in order to exploit this in inhibitor design. We expressed the catalytic domain of rat Ins(1,4,5)P3 3-kinase A in Escherichia coli as a His- and S-tagged fusion protein. The purified enzyme was used in an Ins(1,4,5)P3 kinase assay to phosphorylate a series of inositol phosphate analogues with three or four phosphate groups. A synthetic route to D-2-deoxy-Ins(1,4,5)P3 was devised. D-2-Deoxy-Ins(1,4,5)P3 and D-3-deoxy-Ins(1,4,6)P3 were potent inhibitors of the enzyme, with IC50 values in the micromolar range. Amongst all analogues tested, only D-2-deoxy-Ins(1,4,5)P3 appears to be a good substrate of the Ins(1,4,5)P3 3-kinase. Therefore, the axial 2-hydroxy group of Ins(1,4,5)P3 is not involved in recognition of the substrate nor does it participate in the phosphorylation mechanism of Ins(1,4,5)P3. In contrast, the equatorial 3-hydroxy function must be present in that configuration for phosphorylation to occur. Our data indicate the importance of the 3-hydroxy function in the mechanism of inositol trisphosphate phosphorylation rather than in substrate binding.     

激光粒度仪测定纳米磷酸铁粉体粒度的研究

采用Zetasizer Nano S90型激光粒度分析仪对纳米磷酸铁粉体进行粒度测定的实验研究。主要考察了分散剂及其用量、超声时间、磷酸铁在测定液中的含量等因素对粉体分散性能及粒径测定的影响,确定了纳米磷酸铁粉体粒度分析的最佳条件,即以蒸馏水为分散介质,质量浓度为1 g/L的十二烷基硫酸钠为分散剂,纳米磷酸铁质量浓度为0.2 g/L,超声时间为15 min时,激光粒度仪测得的结果与扫描电镜表征结果基本一致。     

磷矿正-反浮选产品粒度分布与存在问题分析(II)——回水流程实验

通过对浮选产品的粒度分析,指出了某磷矿正反浮选连续性实验(回水流程)存在的问题,并提出了改进建议。     

高性能防锈颜料磷酸锌的研制

采用液-液直接法,利用氧化锌和磷酸来生产磷酸锌。通过控制氧化锌悬浮液的加料速度、分散剂的用量、复合表面改性剂的用量,用吸油量、磷酸锌含量、粒度分布和耐盐雾性能来表征磷酸锌防锈颜料的最佳制备工艺。     

生产饲料级磷酸氢钙的新工艺

介绍了我国硫酸法生产饲料级磷酸氢钙的工艺,指出了其存在的问题,并提出了一种新的工艺。新工艺的实验结果表明,产品平均粒径达到60~70μm,湿含量下降到18.7%,中和后的水能满足化灰所需用量。新工艺提高了产品的质量,降低了能耗,也促进了水的循环利用。     

The presence of calcite in archeological ceramics

The present work describes the methods for detecting and classifying calcite in archeological ceramics, the forms of calcite and their interpretation in archeometric terms. Calcite appears in form of coarse granules and fine particles, and its origin can be primary or secondary. Coarse granules can be polycrystalline or mono-crystals of calcite. Fragments of shells, fossils or microfossils are also found. Primary calcite is the initial calcite preserved in low-fired pottery. Secondary calcite, formed after the ceramic firing, may be reformed (re-carbonated) calcite, precipitated calcite or calcite from alteration. The firing can cause the formation of a ‘reaction rim’ around coarse granules of calcite, while strong decomposition of coarse calcite causes the formation of ‘calcite ghosts’. The identification of the forms of calcite gives information on raw materials, the firing temperature and the manufacturing technology of the pottery.     

Reactive rock phosphate fertilizers and soil testing for phosphorus: The effect of particle size of the rock phosphate

North Carolina rock phosphate (NCRP) (highly carbonate—substituted apatite) was ground to produce three samples with different particle size distributions. The effectiveness of these fertilizers was compared with the effectiveness of superphosphate in a field experiment and three glasshouse experiments using lateritic soils from south-western Australia. Non-reactive Queensland rock phosphate (low carbonate-substituted apatite from the Duchess deposit) was also used in the pot experiments. Bicarbonate-soluble phosphorus extracted from the soil is widely used in Western Australia to predict plant yields from previously-applied fertilizer dressings. For both field and pot experiments bicarbonate-extractable phosphorus (soil test value) was measured and related to subsequent plant yields.As calculated from the initial slope of the relationship between yield and the level of P applied, finely powdered NCRP was about 5–32% as effective as freshly-applied superphosphate in the year of application and also for two years after application in the field experiment, and for two successive crops in the three pot experiments. For both field and pot experiments, finely powdered NCRP, was at best, 1.5–2.0 times as effective as granular NCRP. Relative to freshly-applied superphosphate, the effectiveness of rock phosphates usually decreased with increasing level of application.For each of the crops in the field experiment, the relationships between yield and phosphorus content of plants (i.e. internal efficiency curves) were similar for all fertilizers. Thus the low effectiveness of the rock phosphates relative to superphosphate was solely due to much less phosphorus being taken up by plants. By contrast, in the pot experiments internal efficiency curves differed for different fertilizers. This is attributed to differences in the rate of phosphorus uptake by plant roots during the early stages of plant growth.For both field and pot experiments, soil test calibrations (the relationship between yield and soil test value) differed for rock phosphates and superphosphate. For superphosphate, soil test calibrations also differed for the three different years after the initial application of this fertilizer in the field experiment. For the second crop in the pot experiment, soil test calibrations differed for superphosphate applied at different times (before the first and the second crop). These results point out the difficulty of applying soil testing procedures to soils that have experienced different histories of fertilizer application.     

典型阴离子杂质对磷酸二氢钠结晶过程影响

采用间歇冷却结晶法研究了工业上生产磷酸二氢钠的原料湿法磷酸中典型阴离子杂质SO42-、F-、Cl－ 等对磷酸二氢钠结晶过程的影响,并以诱导期表征晶核形成,以结晶速率表征晶体生长,以粒度分布、长径比衡量晶体形态。研究结果表明,随着SO42-含量的增加,磷酸二氢钠诱导期和晶体平均粒径逐渐降低,而结晶速率呈现先增加后降低的趋势;随着F-含量的增加,诱导期、结晶速率、平均粒径均逐渐增大;随着Cl-含量的增加,诱导期减小,而结晶速率变大,平均粒径先增大后减小。此研究成果可用于指导湿法磷酸制备磷酸二氢钠的工业生产。     

烟酸肌醇酯的合成

对烟酸肌醇合成过程中反应温度、溶剂吡啶含水量等因素对收率的影响作了探讨 ,结果表明 ,酰氯化反应温度 40℃～ 45℃ ,吡啶含水量≤ 0 2 % ,为最佳合成条件     

Adsorption characteristics of glycols on calcite and hematite

Monoethylene glycol, diethylene glycol, and triethylene glycol can be used for hydrate prevention during transport of liquids and gases, in dehumidifiers, for controlling growth of hematite nanoparticles and in the precipitation of different calcium carbonate morphologies. In all these applications, glycols may interact with calcite or hematite or both. Molecular dynamics and electronic structure calculations were used to investigate glycol adsorption on these surfaces. All glycols primarily adsorbed with hydroxyl hydrogen atoms to surface oxygen atoms. Glycol hydroxyl oxygen atoms coordinated toward surface calcium atoms and iron atoms of calcite and hematite, respectively. Glycols generally had a stronger affinity toward un-hydroxylated hematite. However, hydroxylation of hematite reduced the absolute value of glycol adsorption free energies considerably. Molecular conformations changed during adsorption, which affected the free energy profiles. Adsorbed glycols resulted in a dipole moment pointing away from the surfaces.     

方解石颗粒尺寸对白云质灰岩中碱白云石反应的影响

探讨了白云质灰岩中方解石基质对Na＋在岩石中迁移及其对碱白云石反应的影响。采用图像分析法测定不同白云质灰岩样本中方解石颗粒的尺寸,采用N2吸附法测定岩石孔径分布,采用火焰光度计测定养护在80℃、1 mol／L NaOH溶液中岩石柱内部的Na＋含量,采用X-射线内标法定量分析白云质灰岩中碱白云石反应（ ADR）生成的水镁石含量。结果表明,白云质灰岩TS-1、TS-2、GS-2及FHS-1中方解石颗粒中位径分别为4μm、12μm、15μm和33μm;方解石颗粒越小,迁移到岩石内部的Na＋含量越高,岩石中白云石的碱白云石反应程度越高。     

利用磷矿制备饲料添加剂磷酸二氢钙

以磷矿为原料制备磷酸,通过化学沉淀法脱氟除杂质得到净化的磷酸,再将净化后的磷酸与碳酸钙反应制备饲料级磷酸二氢钙.考察了硫酸质量分数、石灰乳用量、反应时间和反应温度4个因素对磷酸二氢钙产率的影响,得到了制备磷酸二氢钙的最佳工艺条件:硫酸质量分数60％,石灰乳用量7.00 g,反应时间1.5h,反应温度50℃.在此最佳工艺...     

斜窄流分级技术在磷矿磨矿回路中的应用研究

在采用斜窄流分级技术进行磷矿开路磨矿产品料浆分级中试,且取得良好技术指标的基础上,在新建磷矿闭路磨矿分级回路作业中首次设计采用了100 m2斜窄流分级箱.生产考查结果表明,分级设备运行稳定,分级效率高达61.79％.设备优良的分级性能,提高了磨矿系统处理能力,改善了磨矿产品粒度特性,产品粒度较好地满足了后续工序技术要求,系统取得了满意的技术经济指标.     

Behaviour and mechanism of enhanced phosphate sorption on loess modified with metals: equilibrium study

BACKGROUND: Phosphate is one of the main contaminants responsible for the eutrophication of surface waters. In developing countries, algae blooming in lakes have threatened the quality of drinking water due to the lack of proper management of phosphate‐containing wastewaters from mining sites and industry. MAJOR RESULTS: The sorption behaviour of phosphate on loess modified by metals (Zn(II), Cu(II) and Pb(II)) was investigated in this paper. Zn(II) and Cu(II) sorption on the loess was attributed to the constituent silicate minerals while the sorption of Pb(II) was assigned to natural carbonate in the loess. The sorption affinity of phosphate towards the modified sorbent was as follows: Pb(II) (221.3–832.2 L g⁻¹) > Cu(II) (20.26 L g⁻¹) > Zn(II) (0.77–1.90 L g⁻¹) > loess (0.11 L g⁻¹) with regard to the partition coefficient. The sorption isotherms were well fitted by an extended Henry's law with multi‐linearity. Several factors including metal loading, pH, sorbent dosage and temperature were investigated and all were found to correlate positively with phosphate sorption. The enthalpy and entropy changes during phosphate sorption on Pb(II) loaded loess were predicted as 14.32 kJ mol⁻¹ and 128.45 J mol⁻¹ K⁻¹, respectively. The sorption mechanism for phosphate on Pb(II) doped loess was investigated by FT‐IR spectra from which the sorption was attributed to chemical bonding with lead carbonate and physisorption with surface adsorbed phosphate as well as diffusion through micropores into the sorbent. CONCLUSIONS: Pb(II) loaded loess shows the best performance for phosphate removal from aqueous solution. The optimum conditions for sorption were pH = 9.5, lead modified loess sorbent dosage = 10 g L⁻¹, temperature = 35 °C and Pb(II) loading 295 mg g⁻¹. Copyright © 2008 Society of Chemical Industry     

热重分析法测定胶磷矿中白云石和方解石的含量

采用热重分析方法,在升温速率10℃/min、N2流量40 mL/min、等速升温条件下,测定某胶磷矿中白云石和方解石的含量。结果表明:570～800℃温度区间白云石分解,白云石质量分数为17.85%;600～810℃温度区间方解石分解,方解石质量分数为1.4%。该法操作简单,数据处理快,结果与气量法吻合。     

糖的磷酰化反应研究

选用磷酸氢二钠和磷酸二氢钠的混合盐作酯化试剂与葡萄糖反应,制备了葡萄糖磷酸酯,考察了酯化剂用量、磷酸盐混合物的质量比、催化剂尿素等因素对葡萄糖磷酸酯的取代度和反应效率的影响。结果表明,制备葡萄糖磷酸酯的最佳反应条件为:反应温度80℃,磷酸盐和葡萄糖的质量比为1∶1,磷酸二氢钠与磷酸氢二钠的质量比为3∶1;催化剂加入量为葡萄糖含量的10%,反应时间为6 h。用水作溶剂,合成了水溶性较好的Ca、Cu、Zn等金属磷酸酯配合物,并进行了红外光谱分析。另外,对多糖——纤维素进行磷酰化,测定了其产物的络合能力。     

克林霉素磷酸酯结晶工艺

冷却与溶析的耦合结晶是目前克林霉素磷酸酯工业提纯的主要工艺,也是控制产品质量的的关键步骤.本文考察了克林霉素磷酸酯结晶过程中降温方式、搅拌速率和溶剂配比这3个主要操作因素对结晶质量的影响,包括纯度、粒度分布、溶剂残留等方面.研究结果表明,在实验研究范围内,溶剂配比为D、程序降温控制下,冷却速率为B4或岛、搅拌速率为300～400 r/min方案时可以得到质量最好的产品.     

Adsorption of new hydrophobic polyacrylamide on the calcite surface

A hydrophobic polyacrylamide (HPAM) was synthesized by aqueous free‐radical chain polymerization to understand the adsorption action of the polymer on the calcite during operating stimulation. The polymer was designed as acrylamide (AM)/2‐acrylamide‐2‐methylpropanesulfonic acid (AMPS)/2‐methacryloyloxyethyl 12‐alkyl dimethyl ammonium bromide (MADA). The structure of the polymer was characterized by Fourier transform infrared spectroscopy. The adsorption properties of the polyacrylamide onto pure calcite was investigated. When we compared the ζ potentials of the calcite particles in the presence and absence of HPAM, the adsorbed amount was affected by different factors, and the adsorption behaviors were examined to determine the adsorption layer. The results of the ζ potential measurements indicated that the particles were negatively charged between pHs of 6 and 12, and the presence of HPAM did not reverse that. Equilibrium adsorption studies showed that the adsorbed amount was affected by the concentration of HPAM, liquid‐to‐solid ratio, calcite particle size, concentration of background ions, and temperature, which were related the adsorption behaviors of HPAM. Hydrogen bonds between HPAM and calcite were important because the adsorbed amount was significantly reduced when the hydrogen bonds were broken by urea. It is necessary to develop a more active reagent that can break the hydrogen bonds and improve the effect of hydraulic fracturing. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45314.