Miscibility study of chitosan/polyethylene glycol fumarate blends in dilute solutions

Solution miscibility of chitosan/polyethylene glycol fumarate blends dissolved in acetate buffer solution was investigated in different blend compositions by viscosity, density, and refractive index measurement techniques at 30, 40, and 50°C. In order to quantify the miscibility of the polymer pair, degree of miscibility was studied by means of two criteria known as interaction parameters i.e., μ and α. On the basis of the sign convention involved in these criteria, these values revealed that the blend solution was miscible when the chitosan content was more than 80% (w/w) of the composition. The results were confirmed by density, and refractive index measurements. Furthermore, the results showed that the miscibility window of chitosan/polyethylene glycol fumarate blends was independent with respect to the changes in solution temperature. Therefore, these results suggested due to intermolecular hydrogen‐bonding interaction between amino and hydroxy groups of chitosan and hydroxy groups of polyethylene glycol fumarate which play an important role in the formation of miscible phase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Using Taguchi method to determine optimum process conditions for flue gas desulfurization through an amine scrubber

This study was done to determine the optimum process conditions for absorption of sulfur dioxide in a mixture of flue gases. Using a selective amine-based absorber; a high amount of SO₂ was absorbed in the scrubbing process. The process was designed to reduce the amount of sulfur dioxide. The pilot plant was designed and set up in the Research Center of Petroleum University of Technology, containing absorption and desorption stages. This paper reports an investigation of the effect and optimization of parameters that improve the efficiency of the whole process. The experiments were conducted under varying levels of desorption temperature, pH of the absorber solution, concentration of SO₂ inlet gas, and flow rate of the absorbing solution. Using Taguchi experimental design method, the optimum conditions were identified for the absorption process. An efficiency of more than 99 % could be obtained by varying the parameters in which all the released SO₂ gas was absorbed from the inlet flue gas; an achievement that is much favorable for industrial purposes.     

Synthesis and characterization of CdO nanocrystalline structure by mechanochemical method

Cadmium oxide nanostructure was synthesized by calcining the obtained precursor of a mechanochemical reaction. The milling was carried out with cadmium nitrate tetrahydrate and acetamide reactants without any additives at room temperature. Resulting precursor was calcined at 450 °C for 2 h in a furnace. As a result of heating, the organic section of precursor was removed and cadmium oxide nanostructure was produced. The obtained compound from the mechanical milling (MM) technique possesses a cubic crystalline structure at nanoscale. XRD studies indicate that the obtained CdO has a cubic phase. Also, SEM and TEM images showed that the resulting material is composed of nanoparticles with the average diameter of 41 nm. The average size and standard deviation were calculated using a Microstructure Measurement program and a Minitab statistical software.     

Effect of two horizontal components of earthquake on nonlinear response of torsionally coupled base isolated structures

Torsion in base‐isolated structures using bilinear rubber isolators effected by two horizontal components of earthquake simultaneously is investigated under various principal parameters including number of storeys; ratio of uncoupled torsional frequency to lateral frequency in the superstructure; ratio of uncoupled torsional frequency to lateral frequency in the isolation system; mass eccentricity in the superstructure and isolation system; and, in addition, the direction of eccentricity. Structure was supposed a shear structure and it was modeled by using concentrated mass and springs. Isolators are modelled by using nonlinear springs considering the interaction of isolator behaviour in two directions. The effect of variation in considered parameters on the behaviour of the superstructure and isolation system is investigated under seven ground motions. It is demonstrated that the parameters affect asymmetric structure behaviour with respect to symmetric one. The results of our investigations help us to understand the asymmetric structure behaviour under bidirectional earthquake by comparing it with a symmetric one. These results demonstrate that asymmetry in the superstructure or isolation system could have a significant effect on the torsional behaviour of isolated structures. In addition, the results show that the use of rigid superstructures and calculation of dynamic torsion by multiplying eccentricity by the dynamic base shear are unacceptable assumptions. Torsional effect on the isolated structural behaviour is amplified by considering two horizontal components of earthquake and comparing them with just one horizontal component. Copyright © 2010 John Wiley & Sons, Ltd.     

Aneurysm in a persistent sciatic artery. Apropos of 2 cases

Persistent sciatic is a vascular malformation resulting in the embryo from the preferential growth of the ischiatic posterior axis remaining atrophic. We report here two cases of unilateral, complete and incompleted, persistent sciatic arteries, complicated by buttock aneurysm.     

Using flower pollinating with artificial bees (FPAB) technique to determine machinable volumes in process planning for prismatic parts

Process planning (PP) has an important role in manufacturing systems design and operations. Volume decomposition and machinable volumes (MVs) or machining features determination is the core activity in process planning. This process requires extraction of elementary volumes (EVs), merging or clustering EVs to construct feasible MVs and finally selecting an optimal combination of MVs. Development of MVs is an important activity, so that better solution is obtained by better developed MVs. Generation of limited number of MVs or machining features, which is often performed by experts may miss the optimal solution. Also, using exact methods such as combinatorial optimization not only generate infeasible MVs, but also require an excessive amount of computational time. In this research, the meta-heuristic procedure of flower pollinating by artificial bees (FPAB) is used in manufacturing context to generate and assess the feasibility of MVs. Furthermore, a set-covering method is used to select the optimal solution. The performance of the proposed model is assessed through some numerical examples. The encouraging results of the numerical examples demonstrate good performance of the proposed method in machining feature or machinable volumes determination problem (MVDP).     

Effects of forage provision to dairy calves on growth performance and rumen fermentation: A meta-analysis and meta-regression

A meta-analysis of the potential effect of forage provision on growth performance and rumen fermentation of dairy calves was conducted using published data from the literature (1998–2016). Meta-regression was used to evaluate the effects of different forage levels, forage sources, forage offering methods, physical forms of starter, and grain sources on the heterogeneity of the results. We considered 27 studies that reported the effects of forage provision to dairy calves. Estimated effect sizes of forage were calculated on starter feed intake, average daily gain (ADG), feed efficiency (FE), body weight (BW), and rumen fermentation parameters. Intake of starter feed, ADG, BW, ruminal pH, and rumen molar proportion of acetate increased when supplementing forage but FE decreased. Heterogeneity (the amount of variation among studies) was significant for intake of starter feed, ADG, FE, final BW, and rumen fermentation parameters. Improving overall starter feed intake was greater in calves offered alfalfa hay compared with those offered other types of forages. During the milk feeding and overall periods, improving ADG was greater for calves fed a high level of forage (>10% in dry matter) compared with those fed a low level of forage (≤10% in dry matter) diets. The advantages reported in weight gain at a high level of forage could be due to increased gut fill. Improving overall ADG was lower for calves offered forages with textured starter feed compared with ground starter feed. The meta-regression analysis revealed that changes associated with forage provision affect FE differently for various forage sources and forage offering methods during the milk-feeding period. Forage sources also modulated the effect of feeding forage on ruminal pH during the milk-feeding period. In conclusion, forage has the potential to affect starter feed intake and performance of dairy calves, but its effects depend on source, level, and method of forage feeding and physical form of starter feed independently of grain sources included in the starter feed.     

High-speed contouring enhanced with P-H curves

In this paper, Pythagorean hodograph (P-H) curve theory is used for high-speed contouring applications. There are large contouring errors around sharp corners when low-bandwidth servo controllers (such as P-PI control) are used. It is possible to construct a P-H curve in the region of sharp corners in order to decrease the amount of cornering error. The developed algorithm is implemented for various corners with different angles. With respect to sharp tool paths, the total machining time is increased by a small amount, but the cornering error is reduced to the allowable tolerance limit. The results of simulation, such as the total cornering time and the cornering error, are compared with previously published methods. It has been shown that the over-corner P-H approach will substantially decrease the amount of cornering error.     

Difference-based target detection using Mahalanobis distance and spectral angle

Two difference-based target detection methods are proposed in this work. In contrast to many target detectors which only calculate the distance between the testing pixel to the target spectrum, the proposed methods calculate the distance of the testing pixel to both of target and of background spectra. In other words, they utilize the difference between target and background computed distances. The first proposed method uses the Mahalanobis distance and benefits the valuable information contained in the statistics of targets and background. The second proposed method uses the kernel-based spectral angle mapper to benefit the advantages of spectral angle and kernel trick to separate targets from background, especially in non-linear cases. The experiments done on three real hyperspectral images indicate the high detection probability of the proposed methods compared to several target detectors.