酸碱中和单点滴定法研究

本文就酸碱中和单点滴定法的原理、方法和应用进行了讨论。已导出滴定一元、二元弱酸单点法计算公式。讨论了滴定剂加入量与单点法测定结果准确度和精密度的关系。已用本法对试样、标准样品和标准溶液进行了一百多次测定,用HX—20微机处理数据,测定结果相对误差一般小于0.1％,相对标准偏差在0.2％左右。

膨胀石墨的工艺优化及性能研究

利用混酸法与单酸法制备膨胀石墨,通过XRD、FESEM对2种制备方法进行比较并优化工艺条件,对吸附性能进行表征。实验得出,混酸法制备膨胀石墨的最佳工艺为:原料质量配比m(H2SO4)∶m(HNO3)∶m(石墨)=3∶1∶1,m(石墨)∶m(高锰酸钾)=1.00∶0.15,膨化温度为900℃;与单酸法相比,混酸法制备的膨胀石墨膨胀效果明显,吸附性能好,产物结构较规整。

A Simplified Method for Purifying Osteoclasts from Human Giant Cell Tumor of Bone

Objective: To purify and identify the osteoclasts from the tissue of humangiant cell tumor of bone. Methods: We have developed a new method that allows the purification oflarge numbers of authentic osteoclasts (OCs). The OCs were isolated from tissue of human giant celltumor of bone by 0.25% trypsin and collagenase. We characterized OCs in terms of the expression ofdifferent phenotypic markers of OCs. The phenotypic markers of OC included Tartrate-resistant acidphosphatase staining (TRAP). The expression of calcitonin receptor (CTR), cathepsin K and receptoractivator of necrosis factor κB (RANK) mRNA were examined by RT-PCR. Results: The OC cell purifiedby above method functioned normally in vitro. The purity was about 79.7%. They showed the normalosteoclast phenotypes markers of OC. Conclusion: The method provides a system for performingbiochemical and molecular studies of OCs. The study indicates that the method of purifying theosteoclasts from human GCT cell can be used for research of bone metabolism.

Kinetics of Forward Extraction of Boric Acid from Salt Lake Brine by2-Ethyl-1,3-hexanediol in Toluene Using Single Drop Technique

The kinetics of forward extraction of boric acid from salt lake brine by 2-ethyl-1,3-hexanediol in toluene was investigated using the single drop technique. The factors affecting the extraction rate include interfacial area between aqueous phase and organic phase, initial concentration of boric acid in aqueous phase, initial concentration of 2-ethyl-1,3-hexanediol in organic phase, and extraction temperature. The experimental results show that the extraction rate increases with the increase of the initial concentration of boric acid and2-ethyl-1,3-hexanediol, interfacial area of two phases, and temperature. With the temperature-dependence study, it is showed that the extraction is a diffusion-controlled process. The kinetic equation is presented for pH 1.0 in the aqueous phase and temperature of 318 K.

Rock Cutting Analysis Employing Finite and Discrete Element Methods

The petroleum industry has shown great interest in the study of drilling optimization on pre-salt formations given the low rates of penetration observed so far. Rate of penetration is the key to economically drill the pre-salt carbonate rock. This work presents the results of numerical modeling through finite element method and discrete element method for single cutter drilling in carbonate samples. The work is relevant to understand the mechanics of drill bit-rock interaction while drilling deep wells and the results were validated with experimental data raised under simulated downhole conditions. The numerical models were carried out under different geometrical configurations, varying the cutter chamfer size and back-rake angles. The forces generated on the cutter are translated into mechanical specific energy as this parameter is often used to measure drilling efficiency. Results indicate that the chamfer size does not change significantly the mechanical specific energy values, characteristic. Results also show there is a significant increase although the cutter aggressiveness is influenced by this geometrical in drilling resistance for larger values of back-rake angle.

Ba4M（CO3）2（BO3）2（M=Ba, Sr）: two borate-carbonates synthesized by open high temperature solution method

Two borate-carbonates Ba4M(CO3)2(BO3)2(M =Ba, Sr) have been successfully synthesized in the open air representing the first examples of borate-carbnate complex.Their structures were determined by single crystal X-ray diffraction and they both crystallize in same space group, Pnma.Their structures feature a Ba/Sr-based three dimensional framework composed of the BaO8 polyhedra(the SrO8 polyhedra), isolated BO3 and CO3 triangles. Detailed structure analysis shows that the intergrowth of [Ba3(BO3)2]/[Ba2Sr(BO3)2] and [BaCO3] layers favors the formation of these two borate-carbonates. In addition, their syntheses, spectroscopic properties and thermal behaviors were investigated.

Power analysis of principal components regression in genetic association studies

Association analysis provides an opportunity to find genetic variants underlying complex traits. A principal components regression （PCR）-based approach was shown to outperform some competing approaches. However, a limitation of this method is that the principal components （PCs） selected from single nucleotide polyrnorphisms （SNPs） may be unrelated to the phenotype. In this article, we investigate the theoretical properties of such a method in more detail. We first derive the exact power function of the test based on PCR, and hence clarify the relationship between the test power and the degrees of freedom （DF）. Next, we extend the PCR test to a general weighted PCs test, which provides a unified framework for understanding the properties of some related statistics. We then compare the performance of these tests. We also introduce several data-driven adaptive alternatives to overcome difficulties in the PCR approach. Finally, we illustrate our results using simulations based on real genotype data. Simulation study shows the risk of using the unsupervised rule to determine the number of PCs, and demonstrates that there is no single uniformly powerful method for detecting genetic variants.