二合一石墨炉在运行中的问题及解决措施

介绍了二合一石墨炉的生产工艺及运行中出现的问题，提出了整改措施，实施后效果良好。     

Determination of trace metals in naphtha by graphite furnace atomic absorption spectrometry: Comparison between direct injection and microemulsion pretreatment procedures

Naphtha is a volatile petroleum fraction containing C4-C15 hydrocarbon compounds used as feedstock for petrochemical processes which are seriously affected by trace metals. Simple methods for copper, iron, lead and silicon determination in naphtha using graphite furnace atomic absorption spectrometry (GFAAS) have been developed. Two different approaches are presented: direct injection of the sample and oil-in-water microemulsion formation using a mixture of the sample, propan-1-ol and nitric acid aqueous solution. The calibration curves showed linear response for each concentration range with correlation coefficients ranging from 0.9728 to 0.9998. Precision figures of 1.7-20%, reported as the relative standard deviation, were calculated from at least twenty consecutive measurements of solutions containing the metal in a concentration level below 100 μg L⁻¹. The characteristic masses varied from 8.5 to 44 pg and the limit of detection, defined as the metal concentration that gives a response equivalent to three times the standard deviation of the blank (n = 10), was found to be within the range 0.01-26 μg L⁻¹. A critical analysis is presented by the authors emphasizing the advantages and limitations of both approaches. The proposed procedures have been used for copper, iron, lead and silicon determination in naphtha feeds processed in Braskem S.A. (Camacari, Bahia, Brazil).     

Interfacial reactions between magnesia refractory and electric arc furnace (EAF) slag with use of direct reduced iron (DRI) as raw material

Interfacial reactions between the electric arc furnace (EAF) slag, i.e., CaO–SiO₂–FeO–MgO–Al₂O₃–MnO system, and the magnesia refractory as a function of direct reduced iron (DRI) addition (0, 10, 20, 30 wt%) were investigated at 1550 °C under an Ar atmosphere. MgO solubility increases with increasing DRI content by decreasing basicity (i.e., CaO/SiO₂ ratio), which is due to an increase in SiO₂ supplied from DRI. The measured MgO content was always lower than the theoretical MgO saturation level irrespective of DRI content because the magnesiowüstite (MW) intermediate layer, which formed at the slag/refractory interface, retarded the direct dissolution of the refractory by acting as a self-protective layer. The thickness of the MW intermediate layer and dissolution depth were proportional to DRI content. However, the penetrativity decreased with increasing DRI content by decreasing the fluidity of the slag. Several kinetic parameters were estimated, including the dissolution rate constant of the MW intermediate layer, the dissolution rate of the MgO refractory, and the rate constant of MW growth. Dissolution of MgO refractory is controlled by the dissolution of the MW intermediate layer. Increasing the growth rate is very important for protecting refractory after the formation of a MW intermediate layer. In addition, we provided a schematic diagram of the slag/refractory interfacial reaction phenomena that compares situations of low and high DRI content. The results of the present study show that it is necessary to control DRI content to minimize refractory degradation during the EAF process. If a large amount of DRI must be used in the EAF process, then MgO content in the slag should be at the saturation limit at first, which accelerates growth of the MW intermediate layer.     

Interaction of vanadium containing catalysts with microwaves and their activation in oxidative dehydrogenation of ethane

Microwave (MW)-activated oxidative dehydrogenation of ethane is studied using kinetic approach. It consists in the comparison of kinetic dependencies (shape of kinetic equations, “selectivity or yield vs. conversion” curves) and apparent parameters (activation energies) obtained in thermal and MW modes. In the case of VMo and VMoNb oxides a distinct difference between ethane yields was observed at given conversion of limiting reactant (oxygen). It was proven by X-ray diffraction that MW activation changes the catalyst microstructure forming phase distribution different from that formed under a conventional heating and thus changing catalytic behavior of VMo and VMoNb oxides.     

不对称催化中的手性配体和底物之间的相互作用

讨论了手性配体和底物之间的相互作用及其在对映选择催化中的应用。     

Interaction between La and MP-11 in the physiological solution

In this paper, the interaction between La³⁺ and microperoxidase-11 (MP-11) in the imitated physiological solution was investigated with the electrochemical method, circular dichroism (CD) and ultraviolet-visible (UV-vis) absorption spectroscopy. It was found that the interaction ways between La³⁺ and MP-11 are different with increasing the molar ratio of La³⁺ and MP-11. When the molar ratio of La³⁺ and MP-11 is less than 2, La³⁺ mainly interacts with the metacetonic acid group of the heme group in the MP-11 molecules, causing the increase in the non-planarity of the porphyrin cycle in the heme group and the decrease in the content of the random coil conformation of MP-11. These structural changes would increase the exposure extent of the electrochemical active center of MP-11 and thus, La³⁺ can promote the electrochemical reaction of MP-11 and its electrocatalytic activity for the reduction of H₂O₂ at the glassy carbon (GC) electrode. However, when the molar ratio of La³⁺ and MP-11 is larger than 3, except binding to the carbonyl oxygen of the metacetonic acid group in the heme group, La³⁺ interacts also with the oxygen-containing groups of the amides in the polypeptide chains of the MP-11 molecules, leading to the increase in the contents of the random coil conformation in the peptide of the MP-11 molecule, comparing with that for the molar ratio of less than 2. However, the non-planarity of the porphyrin cycle in the heme group is similar to that for the molar ratio of less than 2. Perhaps, the increase in the contents of the random coil conformation in the peptide of the MP-11 molecule would partially shield the electrochemical active center of MP-11 and is not favorable to the electrochemical and electrocatalytic reaction of MP-11. Thus, the reversibility of the electrochemical reaction of MP-11 and its electrocatalytic activity for the reduction of H₂O₂ are lower than that for the molar ratio of less than 2.     

Interaction of powdery Al, Zr and Ti with atmospheric nitrogen and subsequent nitride formation under the metal powder combustion in air

The combustion process in air for aluminum nanopowders (nAl), micron-sized powders of aluminum (μAl), titanium (μTi) and zirconium (μZr) was accompanied by the predominant reaction of the metals with N₂ and the subsequent stabilization of the nitride phases (from 38 wt.% of ZrN for μZr combustion to 72 wt.% of AlN for nAl combustion) in the condensed combustion products (CCP). The combustion process, composition and structure of CCP of nAl, μAl, μTi, and μZr were studied. Scanning electronic microscopy (SEM), X-ray diffraction (XRD), energy dispersive (X-ray) spectroscopy (EDX), and chemical analysis were performed on both initial powders and CCP. The combustion mechanism for the studied metal powders was experimentally proved. The formation of a large amount of non-equilibrium products (AlN, ZrN, TiN) instead of oxides in air is the special feature of the above mentioned experimental conditions. Nitride formation in air was defined by high temperatures and high burning rates during combustion of powdery Al, Ti and Zr.     

微波消解-石墨炉原子吸收光谱法测定桂皮中铅、镉、铬、锑、镍和铜

建立了微波消解-石墨炉原子吸收光谱法测定桂皮中的铅、镉、铬、锑、镍、铜。结果表明,在选定实验条件下,各元素标准曲线相关系数均超过0.99,精密度RSD值均低于5%,加标回收率在97.75%~100.95%。该方法具有简便、快速、准确和灵敏度高的优点,适用于桂皮中铅、镉、铬、铜、镍、锑的测定。     

铈锆复合氧化物催化HCl氧化中相互作用机制

采用浸渍法制备了不同负载量的ZrO₂/CeO₂·（xZr/Ce）和CeO₂/ZrO₂·（yCe/Zr）两组催化剂。并采用XRD、Raman、N₂-Sorption、TEM和H₂-TPR等手段对xZr/Ce和yCe/Zr的结构和性质进行表征,并结合HCl催化氧化活性研究CeO₂与ZrO₂在反应体系中的相互作用。结果显示,CeO₂表面掺杂适量的Zr⁴⁺可以增加xZr/Ce表面氧空位浓度,提高其HCl氧化反应活性;但当CeO₂表面掺杂过量的Zr⁴⁺,Zr元素会以ZrO₂的形式存在于xZr/Ce表面,覆盖氧空位,降低了xZr/Ce的反应活性。对于yCe/Zr催化剂,ZrO₂表面高分散的CeO₂有利于催化活性的提高,但ZrO₂表层负载的CeO₂对催化活性的贡献具有阈值,当CeO₂负载量超过10%后,额外增加的铈物种对催化活性已无显著促进作用;对比发现xZr/Ce的氧空位主要来自于铈锆固溶体,yCe/Zr的氧空位主要来自于高分散的CeO₂,由铈锆固溶体产生的氧空位对活性提升更有利;与纯组分CeO₂相比,xZr/Ce与yCe/Zr两组催化剂在苛刻条件下的长期稳定性测试中均表现出高反应稳定性。     

工艺因素对电炉顶用高铝质浇注料性能的影响

首先采用70%(质量分数,下同)的特级矾土骨料(粒度8～5mm、5～3mm、3～1mm与<1mm的质量比分别为5:25:20:20、10:20:20:20、15:15:20:20和20:20:10:20)与30%的基质细粉(由22%的矾土粉、5%的CA80水泥、3%的SiO2微粉和0.2%(外加)的三聚磷酸钠组成)制成不同骨料粒度组成的高铝浇注料试样,检测其烘干强度,以此确定此浇注料合适的骨料粒度级配,然后在此骨料粒度级配基础上,分别研究了矾土粉(<0.088mm)加入量(分别为20%、25%、30%和35%)、骨料颗粒形状、结合剂种类(CA80和Secar-71水泥)及其加入量(1%、3%、5%和7%)、SiO2微粉加入量(1%、2%、3%和4%)、α-Al2O3微粉加入量(1%、3%、5%和7%)、分散剂三聚加入量(0.10%、0.15%、0.20%、0.25%和0.30%)和三聚 六偏加入量(0.05%、0.10%、0.15%和0.20%)对高铝烧注料烘干及中、高温处理后性能的影响。结果表明:骨料粒度组成以8～5mm、5～3mm、3～1mm与<1mm的质量比为10:20:20:20为好;基质细粉加入量以30%为宜;颗粒形状浑圆制备的试样强度不如不规则形状颗粒的;浇注料结合系统采用5%的CA80水泥,然后添加3%硅微粉或者3%～5%的氧化铝微粉,以及0.2%三聚磷酸钠和六偏磷酸钠复合减水剂制备的浇注料的性能较好。     

Modelling the complex interactions between reformer and reduction furnace in a midrex‐based iron plant

This article studies the complex mass and energy interactions between the reformer and the reduction furnace in an iron plant based on Midrex technology. The methodology consists in the development of rigorous first principle models for the reformer and the reduction furnace, in addition to models for auxiliary units such as heat recuperator, scrubber and compressor. In this regard, a one‐dimensional heterogeneous model for the catalyst tubes which takes into account the intraparticle mass transfer resistance was developed for the reformer unit, while the furnace was modelled with bottom‐firing configuration. As for the reduction furnace, the mathematical model was based on the concept of shrinking core model. The furnace was modelled as a moving bed reactor taking into consideration the effects of water gas shift reaction, steam reforming of methane and carburisation reactions. The model was first validated using data from a local iron/steel plant and was then simulated to determine key output variables such as bustle gas temperature, degree of metalisation, carbon content, ratio of hydrogen to carbon monoxide, reductants to oxidants ratio and required compression energy. The effects of key input parameters on the performance of the plant were studied. These parameters included recycle ratio, scrubber exit temperature, injected oxygen flow rate, flow rate of natural gas after reformer, to transition zone, to reformer and to cooling zone. Useful profiles were compiled to illustrate the results of the sensitivity analysis. These results may serve as guidelines for a further optimisation of the plant.     

维C和左氧氟沙星对白蛋白的荧光淬灭研究

通过荧光光谱法研究了在维生素C存在下左氧氟沙星对牛血清白蛋白的荧光淬灭作用。在模拟生理条件（pH=7.4,37℃）下,根据Stem-Volmer方程,确定了在维生素C存在条件下,左氧氟沙星与牛血清白蛋白的淬灭类型仍为静态淬灭,左氧氟沙星对牛血清白蛋白的荧光淬灭减弱,结合常数和结合位点均变小。为研究左氧氟沙星和维生素对蛋白质构象的影响等提供了重要信息。     

Interaction between partitioning porous plate and rising bubbles in a trayed bubble column

In a trayed bubble column, the structure of the partitioning plate plays an important role on the bubble behavior. This study examined the effect of the opening ratio and pore size of the plate on the bubble break-up frequency and bubble size distribution. The sieve tray was used as the partitioning plate. The opening ratio was closely related to gas cap development. The stagnation of bubble flow and a gas cap were observed with an opening ratio less than 48.5%. The gas cap increased with decreasing opening ratio and increasing superficial gas velocity. The main effect of the sieve tray could be categorized into the additional drag force and bubble break-up depending on the sieve pore size. When the sieve pore size was smaller than the Sauter diameter of the bubble swarm, the movement of rising bubbles was interrupted by the drag force applied by the surrounding mesh lines. On the other hand, when the sieve pore size was larger than the Sauter diameter, the bubbles were affected by the additional bubble break-up. After the bubbles penetrated the sieve tray, the bubble size distribution shifted to a smaller one and the Sauter diameter decreased.     

橡胶硫化中纳米碳酸钙粒子网络与交联网络的相互影响

用橡胶加工分析仪（RPA）分析硫化程度对未硫化天然橡胶（NR）的动态性能影响。结果表明,不同硫化程度的混炼胶储能模量随硫化时间的增加而增加,损耗因子降低,NR在0．8倍的正硫化时间（t90）时储能模量最大,损耗因子变化最小。交联密度（Mc）和／△G＇（△G’=G’max-G’min）的值随硫化时间的增加而增大,当体系Mc增大时,△G’也随之增大,说明交联网络和粒子网络存在相互作用。由扫描电镜（SEM）图可以看出,在0．8倍的正硫化时间,交联网络与粒子网络相互作用明显,进一步验证了粒子网络和交联网络之间的相互影响。     

填充床中气体流动与气固反应的相互作用

对界面化学反应和粒内扩散联合控制的气固反应,考虑到反应造成的混合气体质量和密度的变化,研究了填充床中等温条件下的快速气固反应和气体运动的相互作用,建立了相应的数学模型.数值分析表明,按耦合分析和非耦合分析得到的混合气体速度完全不同;忽略反应造成的混合气体密度变化,相当于增加一个额外的源项或汇项,因此当反应气体与惰性气体摩尔质量相差较大时,不能忽略反应造成的混合气体密度变化;按耦合分析和非耦合分析得到的浓度场也有很大差别,反应气体浓度波(物质波)阵面的差别也很大;化学反应明显地阻滞反应气体浓度波的推进;当平均压力降和其他条件相同时,反应器越长波阵面推进的量纲1距离越短;反应活跃区的发展对速度场的影响极大.     

Interaction between Galectin-3 and Integrins Mediates Cell-Matrix Adhesion in Endothelial Cells and Mesenchymal Stem Cells

Galectin-3 (Gal-3) is a β-galactoside-binding protein that influences various cell functions, including cell adhesion. We focused on the role of Gal-3 as an extracellular ligand mediating cell-matrix adhesion. We used human adipose tissue-derived stem cells and human umbilical vein endothelial cells that are promising for vascular tissue engineering. We found that these cells naturally contained Gal-3 on their surface and inside the cells. Moreover, they were able to associate with exogenous Gal-3 added to the culture medium. This association was reduced with a β-galactoside LacdiNAc (GalNAcβ1,4GlcNAc), a selective ligand of Gal-3, which binds to the carbohydrate recognition domain (CRD) in the Gal-3 molecule. This ligand was also able to detach Gal-3 newly associated with cells but not Gal-3 naturally present on cells. In addition, Gal-3 preadsorbed on plastic surfaces acted as an adhesion ligand for both cell types, and the cell adhesion was resistant to blocking with LacdiNAc. This result suggests that the adhesion was mediated by a binding site different from the CRD. The blocking of integrin adhesion receptors on cells with specific antibodies revealed that the cell adhesion to the preadsorbed Gal-3 was mediated, at least partially, by β1 and αV integrins—namely α5β1, αVβ3, and αVβ1 integrins.     

Interaction between Bitumen and Fines in Oil Sands Extraction System: Implication to Bitumen Recovery

Colloidal interactions between bitumen and fines, extracted directly from oil sand ores, were investigated with zeta potential distribution measurement and surface force measurement using an atomic force microscope (AFM). Fines from good processing ores exhibit a negligible attachment to bitumen surfaces, due to hydrophilic nature of the fines. Fines from poor processing ores exhibit a stronger attachment to bitumen surfaces by an attractive hydrophobic force between bitumen and fines, due to hydrophobic nature of the fines and the presence of high concentration divalent cations in the processing water.     

Stage-Specific Genetic Interaction between FgYCK1 and FgBNI4 during Vegetative Growth and Conidiation in Fusarium graminearum

CK1 casein kinases are well conserved in filamentous fungi. However, their functions are not well characterized in plant pathogens. In Fusarium graminearum, deletion of FgYCK1 caused severe growth defects and loss of conidiation, fertility, and pathogenicity. Interestingly, the Fgyck1 mutant was not stable and often produced fast-growing spontaneous suppressors. Suppressor mutations were frequently identified in the FgBNI4 gene by sequencing analyses. Deletion of the entire FgBNI4 or disruptions of its conserved C-terminal region could suppress the defects of Fgyck1 in hyphal growth and conidiation, indicating the genetic relationship between FgYCK1 and FgBNI4. Furthermore, the Fgyck1 mutant showed defects in polarized growth, cell wall integrity, internalization of FgRho1 and vacuole fusion, which were all partially suppressed by deletion of FgBNI4. Overall, our results indicate a stage-specific functional relationship between FgYCK1 and FgBNI4, possibly via FgRho1 signaling for regulating polarized hyphal growth and cell wall integrity.