Probabilistic, fractal, and related techniques for analysis of engineering surfaces

n many engineering fields surface topography is of crucial importance solving problems offriction and other problems of tribology. A review of mathematical approaches for descriptionof topography of engineering surfaces is presented. Firstly, we give a brief introduction to someof statistical parameters used for description of surface roughness. It is argued that althoughsome of these parameters may be quite useful for specific engineering problems, a set of finitenumbers of parameters cannot describe contact properties of rough surfaces. Then we discussvarious models of surface roughness based on Gaussian models of the asperity heights.The results of application of various modern tests of normality for checking whether thedistribution of the asperity heights is Gaussian, are presented. Further fractal models of rough-ness are discussed. Using fractal parametric-homogeneous (PH) surfaces, it is demonstratedthat tribological properties of a rough surface cannot be characterized just by the fractaldimension of the surface. It is also shown that models based solely on the power-spectraldensity function (PSDF) are quite similar to fractal models and these models do not reflecttribological properties of surfaces. In particular, it is demonstrated that different profiles mayhave the same PSDF

Combinatorial search of superconductivity in Fe-B composition spreads

We have fabricated Fe-B thin film composition spreads in search of possible superconducting phases following a theoretical prediction by Kolmogorov et al.^1 Co-sputtering was used to deposit spreads covering a large compositional region of the Fe-B binary phase diagram. A trace of superconducting phase was found in the nanocrystalline part of the spread, where the film undergoes a metal to insulator transition as a function of composition in a region with the average composition of FeB_2. The resistance drop occurs at 4K, and a diamagnetic signal has also been detected at the same temperature. The superconductivity is suppressible in the magnetic field up to 2 Tesla.Comment: 11 pages, 4 figure

Studies on the formation and forming mechanism of the related substance E in potassium clavulanate production by HPLC-MS/MS

O objetivo deste estudo foi investigar a formação da substância E e o respectivo mecanismo na produção de clavulanato de potássio. Confirmou-se a impureza com tempo de retenção de 11,1 min no produto final, clavulanato de potássio, como substância E, por meio de cromatografia líquida de alta eficiência, em conjunto com detecção por espectrometria de massas (CLAE-MS-MS). A análise da substância relacionada E durante a produção do ácido clavulânico mostrou que essa impureza pode ser formada tanto durante a fermentação quanto durante os processos de purificação, especialmente no estágio final de fermentação, filtração, concentração e procedimento de extração. O ácido clavulãnico foi o precursor da substância E. Estudos no mecanismo de sua formação mostraram que a substância E formou-se pela combinação do grupo imina da molécula do ácido clavulânico com o grupo carboxílico de outra molécula de ácido clavulânico, com a abertura do anel β-lactâmico. Resultados do teste ortogonal multifatorial confirmaram que a concentração do ácido clavulânico foi o fator dominante para acelerar a reação, enquanto a temperatura foi outro fator que contribuiu. O pH de 5,0 a 6,5 teve pouco impacto na geração da substância E.The objective of this study was to investigate the formation and forming mechanism of the related substance E in potassium clavulanate production. The impurity with retention time of 11.1 min in potassium clavulanate final product was confirmed as the related substance E by high performance liquid chromatography with tandem mass spectrometric detection (HPLC-MS/MS).The related substance E analysis during the production of clavulanic acid showed that this impurity could be formed during both the fermentation and purification processes, especially in the later fermentation stage, filtration concentration and back-extraction procedure. Clavulanic acid was the precursor of the related substance E. Studies on its forming mechanism showed that the related substance E was formed by the combination of the imino group of one molecule of clavulanic acid with the carboxyl group of another molecule of clavulanic acid with the opening of β-lactam ring. Results of a multi-factor orthogonal test confirmed that the concentration of clavulanic acid was the dominant factor to accelerate the reaction, while the temperature was another contributing factor. The pH 5.0-6.5 had little impact on the generation of the related substance E

Research Progress on Formaldehyde‐Free Wood Adhesive Derived from Soy Flour

Soy‐based adhesives have been regarded as the most suitable candidates for wood industry. For a widespread use of soy‐based adhesives, new technologies need to be developed to improve the water resistance. An overview on the methods to improve water resistance of soy‐based adhesives is presented. Denaturants were once considered necessary to modify soy protein. However, water‐resistant soy adhesives could be prepared by simply removing water‐soluble carbohydrates and low molecular peptides from soy flour. In addition, proper grafting and cross‐linking agents help to prepare water‐resistant soy‐based adhesives, which are used widely to bond interior wood composites. In particular, a new type of polyamidoamine (PADA) resin and an itaconic acid‐based polyamidoamine‐epichlorohydrin (IA‐PAE) resin were synthesized to perform as cross‐linking agents for soy‐based adhesives. This review concludes that soy‐based adhesives have great potential for use in numerous applications. However, future work is still needed to make soy‐based adhesives more competitive with synthetic adhesives

Numerical methods for contact between two joined quarter spaces and a rigid sphere

AbstractQuarter space problems have many useful applications wherever an edge is involved, and solution to the related contact problem requires extension to the classical Hertz theory. However, theoretical exploration of such a problem is limited, due to the complexity of the involved boundary conditions. The present study proposes a novel numerical approach to compute the elastic field of two quarter spaces, joined so that their top surfaces occupy the same plane, and indented by a rigid sphere with friction. In view of the equivalent inclusion method, the joined quarter spaces may be converted to a homogeneous half space with properly established eigenstrains, which are analyzed by our recent half space-inclusion solution using a three-dimensional fast Fourier transform algorithm. Benchmarked with finite element analysis the present method of solution demonstrates both accuracy and efficiency. A number of interesting parametric studies are also provided to illustrate the effects of material combinations, contact location and friction coefficient showing the deviation of the solution from Hertz theory

Engineering Oxygen Vacancy-Rich CeOx overcoating Onto Ni/Al2O3 by Atomic Layer Deposition for Bi-Reforming of Methane

Atomic Layer Deposition (ALD) Was Applied to Develop CeOx-Overcoated Ni/Al2O3 Catalyst for Bi-Reforming of Methane (BRM), as the Combination of Dry Reforming of Methane (DRM) and Steam Reforming of Methane (SRM). Non-Stoichiometric CeOx Thin Films Were Successfully Deposited on Ni/Al2O3 Particles by ALD, Which Constructed a Beneficial Ni-CeOx Interface and Modified the Catalyst Property. Ascribed to the Unique ALD Growth Mode, a High Amount of Ce(III) and Oxygen Vacancies Existed in the ALD-Deposited CeOx overcoating. a Reduction Process Before the BRM Reaction Contributed to the Further Reduction of Ce(IV) to Ce(III), Resulting in More Oxygen Vacancies. the Oxygen Vacancies at the Ni-CeOx Interface Enabled a High Rate of CO2 Activation and Enabled the Balance between the Activation of CO2 and H2O for BRM. Due to its Oxygen Vacancies as Activation Sites for CO2 and H2O, CeOx ALD overcoating Significantly Improved the Activity of Ni/Al2O3 Catalyst and Achieved a Better Control in the H2/CO Ratio with a Suitable Ratio of H2O/CO2/CH4 Feed. CeOx overcoatings Enhanced the Reducibility of Ni(II) Sites and Assisted in Preventing Ni from Oxidation during the BRM Reaction. Less Carbon Deposition Was Achieved by the Ni/Al2O3 Catalyst with CeOx overcoating as Ascribed to its Better Reactant Activation Capacity

(Z)-Ethyl 2,4-diphenyl-3-(propyl­amino)­but-2-enoate

The title compound, C21H25NO2, adopts a Z conformation about the C=C double bond. The mol­ecular structure is stabilized by an intra­molecular N—H⋯O hydrogen bond and the dihedral angle between the aromatic ring planes is 76.04 (12)°. The atoms of the ethyl substituent are disordered over two sets of sites in a 0.60 (2):0.40 (2) ratio