Synthesis and radical polymerization of novel vinyl monomers having the imidazoline and pyrimidine moiety

Summary Alkylation of the methylene bridged tetrahydropyrimidine derivatives by chloromethylstyrene produces the bridged bis(4-vinylbenzyl)-1,4,5,6,-tetrahydropyrimidinium salts in high yields. Similar procedures are used to prepare 2-imidazolinium derivatives. The quaternary salts which support functional side groups of potential biomedical interest are characterized by means of spectroscopic methods. These monomers are readily polymerized free radically in solution of dimethyl formamide at moderate temperatures. The soluble and insoluble polymers containing 2-imidazolinium and 1,4,5,6-tetrahydropyrimidinium salts were found to exhibit antibacterial activites againstEscherichia coli.     

DOPGA: a new fitness assignment scheme for multi-objective evolutionary algorithms

In this article, a new fitness assignment scheme to evaluate the Pareto-optimal solutions for multi-objective evolutionary algorithms is proposed. The proposed DOmination Power of an individual Genetic Algorithm (DOPGA) method can order the individuals in a form in which each individual (the so-called solution) could have a unique rank. With this new method, a multi-objective problem can be treated as if it were a single-objective problem without drastically deviating from the Pareto definition. In DOPGA, relative position of a solution is embedded into the fitness assignment procedures. We compare the performance of the algorithm with two benchmark evolutionary algorithms (Strength Pareto Evolutionary Algorithm (SPEA) and Strength Pareto Evolutionary Algorithm 2 (SPEA2)) on 12 unconstrained bi-objective and one tri-objective test problems. DOPGA significantly outperforms SPEA on all test problems. DOPGA performs better than SPEA2 in terms of convergence metric on all test problems. Also, Pareto-optimal solutions found by DOPGA spread better than SPEA2 on eight of 13 test problems.     

Monitoring of hydrogenation with various catalyst ratios

Soybean oil was hydrogenated using two different nickel-based commercial catalysts (Nysosel 222 and SP-10) at various ratios in 4-L reactors under constant conditions (165°C, 2 bar hydrogen pressure, and 500 rpm stirring rate). Trans isomer formation, reaction rates, selectivity (S) ratios, and melting behaviors of the samples were monitored during the reactions. When Nysosel 222 was used at 0.02, 0.03, and 0.04%, iodine values (IV) were reduced from 130.1 to 70.6, 50.9, and 44.7 and total trans isomers increased from 0 to 34.2, 43.3, and 40.5%, respectively, after 100 min of hydrogenation. However, SP-10 reduced IV from 130.1 to 77.2, 75.7, and 71.3 after 100 min when used at 0.1, 0.15, and 0.2%, respectively, whereas total trans isomers were 58.6, 70.4, and 70.7%. Reaction rates increased with catalyst ratio and time but were higher for Nysosel 222 than for SP-10 although 5–10 times less Nyosel 22 was used than SP-10. Linoleate selectivity (S ₃₂) was almost constant for Nysosel 222, whereas it was higher but fell with time for SP-10. Increasing the catalyst ratio decreased the time needed to reach the highest oleate selectivity (S ₂₁) ratios, and the IV values where the highest S ₂₁ were attained were different for the catalysts. Increases in m.p. of SP-10 samples were slower after IV values of 80 were attained, where S ₂₁ ratios reached to higher values. Solid fat contents (SFC) of these samples fell markedly above 21.1°C, and steeped SFC curves were obtained.     

Comparison of two palladium catalysts on different supports during hydrogenation

Soybean oil was hydrogenated using two different palladium-based catalysts, 5% palladium on carbon (Pd/C) and 10% palladium on alumina (Pd/A), at various ratios in a 4-L reactor under constant conditions (165°C, 2 bar H₂, and 500 rpm stirring rate). Reaction rate, trans isomer formation, selectivity ratios, and melting behaviors of the samples were monitored. Activity of Pd/C was about 10 times higher than that of Pd/A, and the reaction rate showed a strong dependency on the support material. Increases in the concentrations of both Pd catalysts did not have considerable effect on trans formation, which is slightly dependent on support material. Oleate selectivity (S ₂₁) for all runs varied between 2.48 and 30.34, and type of support material did not have an effect on selectivity. Melting behaviors of the samples were mainly dependent on reaction rates.     

Preparation and in-vivo evaluation of dimenhydrinate buccal mucoadhesive films with enhanced bioavailability

Abstract

Dimenhydrinate (DMH)-loaded buccal bioadhesive films for the prevention and treatment of motion sickness were prepared and optimized. This study examines the rate of drug release from the films for prolonged periods of time to reduce or limit the frequency of DMH administration. Based on preliminary studies using various polymers and concentrations, hydroxyethylcellulose (2.5, 3.0, and 3.2%), and xanthan gum (2.8%) were chosen as matrix polymers. The films were analyzed with respect to their mechanical, physicochemical, bioadhesive, swelling, and in-vitro release properties. In in-vivo pharmacokinetic studies, xanthan gum-based DMH buccal film was associated with significantly increased DMH plasma levels between 1 h and 5 h after DMH dosing when compared with an oral drug solution. The area under the curve AUC_{0–7 h} value of the mucoadhesive buccal film was two-fold higher than the oral DMH solution. Histological analysis revealed that DMH films cause mild morphological and inflammatory changes in rabbit buccal mucosa. The DMH buccal film is effective for approximately 7 h, thus representing an option for single-dose antiemetic therapy. This dosage regimen could be particularly beneficial for chain travelers who travel for long periods of time.     

Efficient successor retrieval operations for aggregate query processing on clustered road networks

Get-Successors (GS) which retrieves all successors of a junction is a kernel operation used to facilitate aggregate computations in road network queries. Efficient implementation of the GS operation is crucial since the disk access cost of this operation constitutes a considerable portion of the total query processing cost. Firstly, we propose a new successor retrieval operation Get-Unevaluated-Successors (GUS), which retrieves only the unevaluated successors of a given junction. The GUS operation is an efficient implementation of the GS operation, where the candidate successors to be retrieved are pruned according to the properties and state of the algorithm. Secondly, we propose a hypergraph-based model for clustering successively retrieved junctions by the GUS operations to the same pages. The proposed model utilizes query logs to correctly capture the disk access cost of GUS operations. The proposed GUS operation and associated clustering model are evaluated for two different instances of GUS operations which typically arise in Dijkstra’s single source shortest path algorithm and incremental network expansion framework. Our simulation results show that the proposed successor retrieval operation together with the proposed clustering hypergraph model is quite effective in reducing the number of disk accesses in query processing.     

Multiprocessor task scheduling in multistage hybrid flow-shops: A parallel greedy algorithm approach

Hybrid flow shop scheduling problems have a special structure combining some elements of both the flow shop and the parallel machine scheduling problems. Multiprocessor task scheduling problem can be stated as finding a schedule for a general task graph to execute on a multiprocessor system so that the schedule length can be minimized. Hybrid Flow Shop Scheduling with Multiprocessor Task (HFSMT) problem is known to be NP-hard. In this study we present an effective parallel greedy algorithm to solve HFSMT problem. Parallel greedy algorithm (PGA) is applied by two phases iteratively, called destruction and construction. Four constructive heuristic methods are proposed to solve HFSMT problems. A preliminary test is performed to set the best values of control parameters, namely population size, subgroups number, and iteration number. The best values of control parameters and operators are determined by a full factorial experimental design using our PGA program. Computational results are compared with the earlier works of O?uz et al. [1], [3], and O?uz [2]. The results indicate that the proposed parallel greedy algorithm approach is very effective in terms of reduced total completion time or makespan (C_max) for the attempted problems.     

Online tuning of fuzzy PID controllers via rule weighing based on normalized acceleration

In this study, an on-line tuning method is proposed for fuzzy PID controllers via rule weighing. The rule weighing mechanism is a fuzzy rule base with two inputs namely; “error” and “normalized acceleration”. Here, the normalized acceleration provides relative information on the fastness or slowness of the system response. In deriving the fuzzy rules of the weighing mechanism, the transient phase of the unit step response of the closed loop system is to be analyzed. For this purpose, this response is assumed to be divided into certain regions, depending on the number of membership functions defined for the error input of the fuzzy logic controller. Then, the relative importance or influence of the fired fuzzy rules is determined for each region of the transient phase of the unit step response of the closed loop system. The output of the fuzzy rule weighing mechanism is charged as the tuning variable of the rule weights; and, in this manner, an on-line self-tuning rule weight assignment is accomplished. The effectiveness of the proposed on-line weight adjustment method is demonstrated on linear and non-linear systems by simulations. Moreover, a real time application of this new method is accomplished on a pH neutralization process.     

A comparison of orthogonal cutting data from experiments with three different finite element models

The aim of this study is to compare various simulation models of orthogonal cutting process with each other as well as with the results of various experiments. Commercial implicit finite element codes MSC.Marc, Deform2D and the explicit code Thirdwave AdvantEdge have been used. In simulations, a rigid tool is advanced incrementally into the deformable workpiece which is remeshed whenever needed. In simulations with MSC.Marc and Thirdwave AdvantEdge, there is no separation criterion defined since chip formation is assumed to be due to plastic flow, therefore, the chip is formed by continuously remeshing the workpiece. However, in simulations with Deform2D, the Cockroft–Latham damage criterion is used and elements, which exceed the predefined damage value, are erased via remeshing. Besides this different modeling of separation, the three codes also apply different friction models and material data extrapolation schemes. Estimated cutting and thrust forces, shear angles, chip thicknesses and contact lengths on the rake face by three codes are compared with experiments performed in this study and with experimental results supplied in literature. In addition, effects of friction factor, different remeshing criteria, and threshold tool penetration value on the results are examined. As a result, it has been found that although individual parameters may match with experimental results, all models failed to achieve a satisfactory correlation with all measured process parameters. It is suggested that this is due to the poor modeling of separation.     

Simple diagnostic approach for determining of faulted PV modules in string based PV arrays

This paper proposes a simple diagnostic method to determine the number of open and short circuited PV modules in a string of a PV system by taking into account the economical factor, such as minimum number of sensors. The diagnostic algorithm has as inputs the irradiance level, the PV modules temperature, the number of PV modules present in the string analyzed and its output power. So, just temperature and irradiance sensors, as well as a power meter by string are needed in the monitoring system forming part of the fault diagnostic system. The proposed fault detection method has been successfully validated experimentally.