Synthesis and structural characterization of an alternating double aquo-bridged and single cyano-bridged polymeric barium–iron complex: {[Ba2(phen)4(H2O)6Fe(CN)6]·Cl·2(phen)·3H2O}n

A new alternating double aquo-bridged and single cyano-bridged polymeric complex {[Ba₂(phen)₄(H₂O)₆Fe(CN)₆]·Cl·2(phen)·3H₂O}_n (1) (phen = 1,10-phenanthroline) has been synthesized and structurally characterized. In the crystal structure the two centrosymmetric [Ba₂(phen)₄(H₂O)₆] units are bridged through two trans CN groups of [Fe(CN)₆]³⁻ ion, which results in the formation of a zig-zag polymeric chain. In each [Ba₂(phen)₄(H₂O)₆] unit, the two Ba centers are joined by double aquo bridges. Both the Ba atoms are 9-coordinated with distorted mono-capped square antiprismatic geometry. An elaborate hydrogen bonding system holds the parallel polymeric chains together.     

Microstructure and mechanical properties of mechanically alloyed and spark plasma sintered amorphous–nanocrystalline Al65Cu20Ti15 intermetallic matrix composite reinforced with TiO2 nanoparticles

Multiphase Al₆₅Cu₂₀Ti₁₅ intermetallic alloy matrix composite, dispersed with 10 wt.% of TiO₂ nanoparticles, has been processed by mechanical alloying, followed by spark plasma sintering under pressure in the temperature range of 623–873 K. Differential scanning calorimetry and X-ray diffraction suggest that equilibrium crystalline phases evolve from the amorphous or intermediate crystalline phases. Transmission electron microscopy shows that the composite sintered at 873 K has partially amorphous microstructure, with dispersion of equilibrium, crystalline, intermetallic precipitates of Al₅CuTi₂, Al₃Ti, and Al₂Cu of 25–50 nm size, besides the TiO₂. The composite sintered at 873 K exhibits little porosity, hardness of 5.6 GPa, indentation fracture toughness in the range of 3.1–4.2 MPa√m, and compressive strength of 1.1 GPa. Indentation crack deflection by TiO₂ particle aggregates causes increase in fracture resistance with crack length, and suggests R-curve type behaviour. The study provides guidelines for processing high strength amorphous–nanocrystalline intermetallic composites based on the Al–Cu–Ti ternary system.     

Microstructural evolution and hardness of in situ Al-4.5Cu-5TiB2 composite processed by multiple roll passes in mushy state

In situ Al-4.5Cu-5TiB₂ composite has been processed through stir casting method, in which, the TiB₂ particles have been precipitated in situ by mixed salt route involving reactions between K₂TiF₆ and KBF₄.The as-cast specimens containing 20 volume percent liquid content have been subjected to three mushy state roll passes, each leading to 5 percent reduction in thickness. The grain structure has been found to be globular in the mushy state rolled composites. Measurements along the cross-section have shown decrease in average grain size and increase in hardness, as one proceeds along the direction of rolling. On the other hand, grain size and hardness have been found to be more or less similar, when compared for sections perpendicular to the rolling direction.     

Logistics cost analysis of rice straw for biomass power generation in Thailand

The logistics of the fuel supply have a large impact on the economy of a biomass power generation facility, especially for low density biomass fuels like straw. A detailed cost analysis of a typical rice straw logistics process for two baling options in three regions of Thailand shows that the costs for all logistics operations vary from a minimum of 18.75 USD/t for small rectangular bales in the Northern region of Thailand to maximum 19.89 USD/t for large rectangular bales in the North-eastern region. The difference in costs is not very significant due to the higher ownership and operating costs of the equipment for using large rectangular bales; however, the specific fuel consumption cost is substantially lower by around 17.5% and a total transport cost reduction is about 31.5%. Analysis of the logistics economies of scale for projected power plant capacities of 2-35 MW_e showed that each doubling the capacity of the energy facility increases the specific costs of the logistics operations only by around 4% in all regions.     

Growth kinetics and lipid production using Chlorella vulgaris in a circulating loop photobioreactor

BACKGROUND: Compared with agriculture, microalgae culture promises to be a novel way of producing lipids for both food consumption and transportation fuel (biodiesel) purposes while using a minimal amount of land area. A circulating loop photobioreactor has been used to study the growth kinetics and lipid yield of Chlorella vulgaris growing on carbon dioxide as the sole source of carbon. RESULTS: Because of high photosynthetic active radiation (PAR) fluxes, C. vulgaris was observed to grow in exponential mode. The highest growth rate achieved was 0.049 h^?1 at the optimum growth conditions of 71.8 mW L^?1 PAR density, 10% CO₂ (v/v) in air and with an applied 8 h dark phase. The microalgae was observed to grow in a Monod fashion with a PAR density saturation coefficient of 2.8 mW L^?1. Light intensity showed the potential to significantly increase lipid yield, which reached a maximum of 30% (by mass) of cell dry weight. CONCLUSION: The circulating loop photobioreactor is a low‐cost bioreactor technology capable of culturing photosynthetic microalgae at high PAR densities and with uniform mixing and lighting. C. vulgaris is able to grow exponentially in this bioreactor and produce lipids at concentrations up to 30% by cell dry weight. Copyright © 2011 Society of Chemical Industry     

Effect of Thermal Cycling on Creep Behavior of Powder-Metallurgy-Processed and Hot-Rolled Al and Al-SiC Particulate Composites

The tensile creep behavior of powder metallurgy (P/M)–processed and hot-rolled commercially pure Al and Al-5 or Al-10 vol pct SiC particulate composites has been evaluated after subjecting to 0, 2, and 8 thermal cycles between 500 °C and 0 °C with rapid quenching. The images of microstructures obtained using scanning and transmission electron microscopy as well as changes in the electrical resistivity, Young’s modulus, and microhardness have been examined in the samples subjected to thermal cycling, in order to compare the effects of structural damage and strengthening by dislocation generation. The damage is caused by voids formed by vacancy coalescence, and is more severe in pure Al than in Al-SiC_p composites, because the particle-matrix interfaces in the composites act as effective sinks for vacancies. Creep tests have shown that the application of 2 thermal cycles lowers the creep strain rates in both pure Al and Al-SiC_p composites. However, the creep resistance of pure Al gets significantly deteriorated, unlike the mild deterioration in the Al-5 SiC_p composite, while the time to rupture for the Al-10 SiC_p composite is increased. The dislocation structure and subgrain sizes in the Al and in the matrices of the Al-SiC_p composites in the as-rolled condition, after thermal cycling, and after creep tests, have been compared and related to the creep behavior. The dimple sizes of the crept fracture surfaces appear to be dependent on the void density, tertiary component of strain, and time to rupture.     

Combining continuous catalytic regenerative naphtha reformer with thermally coupled concept for improving the process yield

Advancements in the catalytic naphtha reforming process, as one of the main processes in petrochemical industry, contributed to development of continuous catalytic regenerative naphtha reformer units. Increasing the yield of aromatic and hydrogen as well as saving the energy in this process through the application of thermal coupling technique is a potentially interesting idea. This novel idea has been assessed in this paper. In the proposed configuration, continuous catalyst regeneration naphtha reforming process is coupled with hydrogenation of nitrobenzene in a two co-axial reactor separated by a solid wall, where the generated heat in nitrobenzene hydrogenation reaction transfers to naphtha reforming reaction medium through the surface of the tube. A steady-state, homogeneous, two-dimensional model is used to describe the performance of this configuration and a kinetic model including 32 pseudo-components with 84 reactions is considered for naphtha reforming reaction. After validating the model with the commercial data of a domestic plant, the obtained results of coupled reactor are compared by the conventional one. The obtained results show the superiority of CCR coupled reactor against the conventional one.     

Rough-fuzzy collaborative clustering.

In this study, we introduce a novel clustering architecture, in which several subsets of patterns can be processed together with an objective of finding a common structure. The structure revealed at the global level is determined by exchanging prototypes of the subsets of data and by moving prototypes of the corresponding clusters toward each other. Thereby, the required communication links are established at the level of cluster prototypes and partition matrices, without hampering the security concerns. A detailed clustering algorithm is developed by integrating the advantages of both fuzzy sets and rough sets, and a measure of quantitative analysis of the experimental results is provided for synthetic and real-world data.