Theoretical investigations on electronics structure and chemical bonding on iridathiabenzene and iridaoxabenzene

The electronic structure and properties of the iridathiabenzene and iridaoxabenzene isomers have been investigated using the hybrid density functional mpw1pw91 theory. The energetic aspect shows that trans-ortho-isomer is the most stable isomer. This is compatible with principles of minimum energy and minimum polarizability. Molecular orbital analysis shows a linear correlation between hardness and anisotropic polarizability values for Iridathiabenzene and iridaoxabenzene isomers. The structural and natural bond analysis (NBO) results illustrate electronic delocalization in these rings. Also, the study of non linear optical properties of these molecules indicate a good correlation between β_tot and E(HOMO) for iridathiabenzene. The results from natural bond orbital (NBO) analysis have provided insights into Ir—ligand, P—H_apical and P—H_basal bonding.     

Mechanical and electrochemical effects on surface convection and on emulsification new criteria

Theoretical and experimental studies of surface instability for charged and polarized interfaces between two immiscible liquids are reviewed. A linear analysis of stability shows the role of mechanical and electrochemical para meters for the onset of interfacial convection. Three cases are studied: 1) For the restored Boltzman distribution in bulk phases, the stability is only governed by the interfacial tension through the composition between mechano-chemicaland electrical contributions to the surface free energy; 2) for the non-restored Boltzman distribution, the stability is also governed by the discontinuity of mechanical quantities (density-viscosity) associated with the discontinuity of electrochemical and electrical quantities (dielectric constant-solute concentration-diffusion coefficient, potential drop); and 3) for concentrated charged and dipolar monolayers, the convection criteria of stability are directly related to the discontinuity of mechanical quantities (density-viscosity) associated with the discontinuity of electrochemical quantities (dielectric constant).Additional experiments on emilsification and demulsification were performed in order to verify this last theoretical prediction.     

CO在Pt及其合金表面电化学氧化和吸附的理论研究

文本综述了CO在Pt及其它过渡金属上电化学氧化机理的量子化学研究现状。系统论述了密度泛函理论计算在催化剂对CO电氧化的作用机制和CO与金属间吸附、成键及振动频率方面所给出的详细信息, 并指出了量子化学计算结果对于电极催化剂设计的指导意义。最后, 指出了目前量子化学计算的局限性并展望来其未来发展趋势。     

Comparative study on sorption of individual and coupling cesium and selenium on mudrock

This study focused on sorption mechanism of Cs and Se in mudrock by batch techniques. Batch kinetics tests have been conducted with carriers 10^{− 4}M CsCl and SeO₂ by using individual and coupling radiotracers of ¹³⁷Cs and ⁷⁵Se. The distribution coefficients (K _d ) of Cs in synthetic groundwater (GW) and seawater (SW) showed that there is no interference between individual and coupling value (13 and 6 ml/g). Moreover, individual and coupling K _d ) (80 and 40 ml/g) of Se in GW and SW are in agreement with Cs. It is quite clear that the sorption mechanisms of Cs and Se on mudrock are independent and different by using radiotracer’s technique.     

Studies on the Adsorption and Dissociation of Methane and Carbon Dioxide on Nickel

The adsorption and dissociation of methane and carbon dioxide for reforming on nickel catalysts were extensively investigated by TPSR, TPD, XPS and pulse reaction methods. These studies showed that the decomposition of methane results in the formation of at least three kinds of surface carbon species on supported nickel catalysts. Carbidic Cα, carbonaceous Cβ and carbidic clusters Cγ surface carbon species formed by the decomposition of methane demonstrated different surface mobility, thermal stability and reactivity. Carbidic Cα is a very active and important intermediate in carbon dioxide reforming with methane, and the carbidic clusters Cγ species might be the precursor of surface carbon deposition. The partially dehydrogenated Cβ species can react with H2 or CO2 to form CH4 or CO. On the other hand, it was proven that CO2 can be weakly adsorbed on supported nickel catalysts, and only one kind of CO2 adsorption state is formed. The interaction mechanism between the species dissociated from CH4 and CO2 during reforming was then hypothesized.     

Hydrogen Electrocatalysis on Single Crystals and on Nanostructured Electrodes

We investigate hydrogen evolution on plain and nanostructured electrodes with a theory developed by us. On electrodes involving transition metals the most strongly adsorbed hydrogen is often only a spectator, while the reaction proceeds via a weakly adsorbed species. For Pt(111) the isotherms for both species are calculated. We explain why a nanostructure consisting of a monolayer of Pd on Au(111) is a good catalysts, and predict that Rh/Au(111) should be even better. Our calculations for a fair number of metals are in good agreement with experiment.     

实验与科学学习——一种认识论的反思

实验作为近代科学的根基,在科学教育中受到了广泛的关注。从认识论的角度,探讨实证主义和否证主义的相关论述将有助于我们重新理解实验在学生科学学习中的功能和作用。     

Structural investigations on zirconium phosphate-phosphite and on itsn-butylamine intercalate

Zirconium phosphate-phosphite have various structure belonging to the drying heat of the sample. While sample dried above sat. NaCl solution had interlayer distance of 1.30 nm (result fromd ₁=0.74 nm andd ₂=0.56 nm for phosphite layer), the sample dried under IR lamp on air having interlayer spacingd=0.74 nm charactderistic for -Zr(HPO₄)₂·H₂O containing little amount of phosphite groups. The composition of the first sample can be characterized by chemical formula, as Zr(HPO₄)_0.7(HPO₃)_1.3· ·0.5H₂O. The X-ray powder diffraction data ofn-butylamine intercalate suggest that in the process take place only the phosphate region of zirconium phosphate-phosphite (ZrPP).     

柴油脱硫的机理研究以及反应中的溶剂效应

柴油的脱硫技术分为加氢脱硫和非加氢脱硫。在非加氢脱硫的研究中,氧化脱硫技术具有反应条件温和、不使用昂贵的氢气、投资和操作费用低等优点日益受到重视。文章介绍了柴油的脱硫技术的机理方面的研究进展。其中包括加氢脱硫的反应网络;以及氧化脱硫研究中,光化学氧化体系和有机过氧化物氧化体系中DBT的氧化机理。在不同的反应体系中,溶剂对含硫化合物的脱除也有很大的影响.     

Porphyrinphosphonate fibers on mica and molecular rows on graphite

meso-Tetra(phenyl-p-phosphonate) porphyrin forms rigid and well-separated fibers of monomolecular thickness (2.8 nm) and lengths of several micrometers on mica at pH 13 (octasodium salt). The formation of these fibers could be observed directly by tapping mode scanning force microscopy (SFM) and was induced by capillary forces. Normal height images or images with a topographical inversion were observed depending on the distance of the SFM tip. Amplitude-distance curves indicated that a stable meniscus was formed on hydrophilic surface areas below a tip-sample separation of 20 nm. The meniscus let the original nanorods appear as ditches in the mica surface and enabled rearrangements. A partly protonated form of the same porphyrin (pH 11.5) gave rows of flat-lying porphyrins on graphite, which appear with molecular resolution in SFM images as well as two-dimensional platelets of monomolecular thickness.     

Investigations on hopeite- and phosphophyllite-containing phosphate coatings on steel

A series of phosphate coatings on steel produced by different procedures and containing differing contents of hopeite and phosphophyllite, are investigated by SEM, XRD, XRF on removed coatings, AES, ESCA, and EDX microanalysis. The morphology of the coatings is mainly determined by the procedure employed (spray or immersion). The hopeite/phosphophyllite ratio of the layers depends on the phosphating bath composition and is quantitatively determinable with sufficient accuracy by XRD, XRF on the removed phosphate layers, and AES. Further results are that an immersion time of more than 60 s does not considerably increase the layer thicknesses and that the first-grown crystalline layers on the steel sheets are hopeite-enriched.     

Micellar effects on dediazoniation and on azo coupling reactions

The effects of a sodium dodecyl sulfate, SDS, micellar solution on the coupling rates of two arenediazonium ions, ArN(2)(+), with the hydrophobic 1-naphthylamine, 1NA and N-(1-naphthyl) ethylenediamine, NED, coupling agents and with the hydrophilic Na salt of 2-naphthol-6-sulfonic acid, 2N6S, have been studied. First, we explored the micellar effects on the thermal decomposition of the arenediazonium ions. The observed rate constants are slightly depressed or increased, depending on the nature of ArN(2)(+), compared to those in pure water upon increasing [SDS]. Estimations of the corresponding association constant to the micelle indicate that a significant fraction of the arenediazonium ions are incorporated into the micelles even at low surfactant concentrations. The sulfonate group in 2N6S prevents its incorporation into the micellar aggregate due to the electrostatic barrier imposed by the micelles and, in consequence, the coupling reaction is inhibited. In contrast, when employing the naphthylamine derivatives, the observed rate constant increase rapidly up to a maximum at [SDS]相似文献   

Research on benzo- and naphthazoles

Fourteen unsymmetrical 1-(1-alkylbenzoimidazolyl-2)-3-methyl-5-arylformazans are synthesized by nitrogen coupling of aryl diazonium salts with acetaldehyde 1-alkylbenzoimidazolyl-2-hydrazones, and their visible absorption maxima are given.For Part XII see [6].     

Researches on allo- and isoalloxazines

The reaction of 7-aminoallo- and isoalloxazines with ethylene oxide is investigated, and its optimum conditions are found. Addition of ethylene oxide to 7-aminoisoalloxazine involves only the cyclic amino group at position 3, while addition to 7-aminoalloxazine involves the cyclic imino group at position 3 and the amino group at position 7.     

Langmuir aggregation of Evans blue on cetyltrimethylammonium bromide and on proteins and its application

The microphase adsorption-spectral correction (MPASC) technique is described and applied to the study of the interactions of Evans blue (EB) with cetyltrimethylammonium bromide (CTAB) and with four proteins: bovine serum albumin (BSA), myoglobin (Mb), hemoglobin (Hb) and ovalbumin (OVA). EB can be adsorbed on a cationic surfactant and on protein by electrostatic force and the aggregation obeys the Langmuir isotherm. Results have shown that the products are formed as follows: monomer aggregate EB·CTAB, micellar aggregate (EB·CTAB)₇₈ and protein aggregates (EB₆₈·BSA), (EB₁₄·OVA), (EB₁₂₆·Mb) and (EB₅₈·Hb). The adsorption constant of the aggregates are calculated to be K_EB·CTAB=2.95×10⁶, K_EB68·BSA=3.40×10⁴, K_EB14·OVA=5.20×10², K_EB126·Mb=6.81×10² and K_EB58·Hb=5.73×10², respectively. The aggregation of EB in proteins is sensitive in the presence of CTAB and selective in the presence of EDTA and it has been applied to the analysis of samples with satisfactory results.     

A brief survey on CLAYPEN and Nanocomposites based on unmodified PE and organo-pillared clays

New clay fillers are mixed with linear low-density polyethylene at 160 °C for 10 min to obtain clay-PE nanocomposites (CLAYPEN) by melt intercalation. Raw montmorillonite (Mt) was pillared (PMt) with partially hydrolyzed Al and Fe salt solutions and further reacted with hexadecyl trimethylammonium bromide (OPMt). For comparison, the hexadecyl trimethylammonium-montmorillonite (OMt) was prepared as a reference material. PE is not intercalated by organoclay. In investigating the pillared clay-PE nanocomposites, XRD is not an appropriate indicator of intercalation of PE, which penetrates into the mesoporous OPMt as shown by TEM. All the nanocomposites have higher Young modulus values than the pristine PE. The best compromise between the other mechanical properties (tensile strength and elongation at break) is obtained with the OPMt-PE nanocomposite. Cone-calorimeter study shows that peak heat release rate value of PE decreases substantially (34%) on addition of 5 phr of this novel OPMt filler.