Magnetic behavior of nickel–bismuth ferrite synthesized by a combined sol–gel/thermal method

The bulk NiFe_2?xBi_xO₄ ferrites with various Bi³⁺ concentration (x=0, 0.1, 0.15) were synthesized via sol–gel procedure, starting from nickel, bismuth and iron nitrate powders, followed by the conventional thermal treatment. The structural and magnetic properties of the as-prepared ferrites were studied by means of X-ray diffraction, alternating gradient force magnetometry and Faraday balance. The anisotropy constant was determined by the law of approach to saturation (LAS) model. An increasing Bi³⁺ concentration in NiFe_2?xBi_xO₄ leads to a decrease in the saturation magnetization, Néel temperature and the anisotropy constant of the material.     

A decision-process model of relational risk and governance and their impact on performance

The purpose of this paper is to investigate the link among risk, governance, and performance. In order to achieve this objective, the paper examines the impact of relational risk on governance decision options (trust, bilateral control, and unilateral control) and performance (design time). Survey research was conducted to collect data from 221 new product development (NPD) relationships and structural equation modeling was conducted to test the hypotheses. The results suggest that relational risk influences trust and bilateral control negatively and unilateral control positively. Results also indicated that trust and bilateral control are positively related to shortened design time while unilateral control and shortened design time are negatively related. We also found that there are threshold effects for modes of governance decision as they influence shortened design time. This study enhances the understanding of NPD relationships by examining the key mechanisms through which governance decision modes are influenced and how they influence NPD performance. In summary, this study shows how relational risk perception through affecting governance decision modes influence shortened design time.     

Palladiumπ - complexes as catalysts for olefin polymerization

Polymerization of different types of olefins was investigated with a $\text{palladium}\text{π-}\text{allylic complex}$ as catalyst. Polymerization was possible only with those olefins which have a bicyclo structure. Compounds with two double bonds reacted as easily as mono-olefins. The effect of temperature on reaction rate was studied and an activation energy of 21.3 kcal/mol calculated for the polymerization reaction of bicyclohepta-2,5-diene.     

Effect of carbon nanotube on cured shape of cross-ply polymer matrix nanocomposite laminates: analytical and experimental study

Cured shape of cross-ply [0₂/90₂]_T fiber-reinforced composite laminates and the effect of multi-wall carbon nanotubes (MWCNTs) on the mechanical and thermal properties of laminates have been investigated. The nanocomposite laminate used in this study is composed of three phases: carbon fiber, polymer matrix and MWCNT. The volume fractions of 0%, 1%, 2% and 3% MWCNT were used to prepare nanocomposites. The mechanical and thermal properties of nanocomposites and fiber-reinforced nanocomposite laminates have been calculated by using analytical micromechanical models. Analytical micromechanical models were applied to determine the mechanical and thermal properties for two-phase nanocomposite composed of MWCNT and polymer matrix. The obtained mechanical and thermal data were considered as matrix properties and used in properties calculation of three-phase fiber-reinforced nanocomposite laminates. A developed model was used to determine curvature and the effect of MWCNT on the curvature in different specimens. Nonlinear relations have been considered for non-mid-plane strain equations. The addition of 1% volume fraction of MWCNT led to decreasing curvature and increasing critical size almost 14% and 9%, respectively, in different directions. The results were used to develop model and to compare with those calculated by Hyer model. Finally, unsymmetrical cross-ply [0₂/90₂]_T laminates with different weight fractions of 0, 0.1%, 0.25% and 0.5% MWCNT were fabricated. The curvature of cured composite laminates, obtained by experimental study, was compared with that developed as Hyer models and good agreements were observed between the predicted model and experimental data. The experimentally predicted and developed model for the curvature of cross-ply [0₂/90₂]_T fiber-reinforced nanocomposite laminates is better than the Hyer model.     

亚洲原油市场在全球中的地位

分析了亚太地区的原油市场供需状况及对全球的影响,并对亚太地区未来10年的原油需求,代应和贸易作了展望。     

Effect of stiffness ratio of piezoelectric patches and plate on stress concentration reduction in a plate with a hole

The effect of piezoelectric patches and plate stiffness on placement and power of piezoelectric actuators for reduction of the stress concentration factor around a hole in a plate under tension is investigated. For this purpose, two conditions are considered: patches are softer than the plate and the plate is softer than the patches. Patches are located at the top/bottom and left/right of a hole. Results show that the stiffness ratio of patches and the plate can affect the best location to reduce the stress concentration factor. Next, by comparing the results, some suggestions are presented for locating the patches. Results are validated by some experimental tests.     

Polymerisation of bicyclohepta-(2,5)-diene with palladium-π-complexes

A pinene-π-allylic complex of palladium was capable of catalysing the polymerisation of bicyclohepta-(2,5)-diene. Polymerisation pattern was the same as in the case of PdCl₂, i.e. only one double bond of the diene was opened by this reaction. The optimum temperature range for the polymerisation was between 130 and 200 °C. Polar solvents retarded the reaction. The Pd-π-allylic complex, for the polymerisation of the same olefin, was a more active catalyst than other palladium compounds (e.g. PdCl₂).     

OPEC's push into refining Dilemma of interactions between crude and product markets

This article shows that the interaction between the crude oil and the product market is not a symmetric phenomenon. A $1.00 change in the price of crude will change the price of the product by only $0.51 (in the short run), while a $1.00 change in the price of refined product will cause a $1.03 change in the price of crude (again, in the short run). The product market is much more sensitive to excess supply than the crude market. Excess supply in the product market will not only depress the price of refined oil, but will also lower the price of crude, with a more significant proportion. At present, the international oil market attempts to avoid the consequences of excess supply in the product market by some sort of subjective coordination of refining capacity utilization. The expected market, however, may change the picture for everyone in the industry — refiners, crude producers and OPEC.     

Polymer-attached palladium-τ-complexes

Palladium-τ-complexes can be attached to polymers producing a new type of palladium catalyst, with the properties of heterogeneous catalysts, for the polymerisation of certain olefins. Two different methods of linkage are described: (a) fixation through a phosphine ligand, and (b) formation of a τ-complex between palladium and polymer support.