Synthesis of hydroxy-terminated polytetrahydrofuran by photoinduced process

Summary This paper describes the preparation of hydroxy-functional telechelics by photoinduced decomposition of polytetrahydrofuran possessing terminal pyridinium ions in THF solution. Hydroxyl functionality was evidenced by end capping and polycondensation with isocyanates.     

Influence of the gas—liquid separator design on hydrodynamic and mass transfer performance of split-channel airlift reactors

Three geometric configurations of gas–liquid separators were used in split-channel airlift reactors (0·1 m³ liquid volume; riser-to-downcomer cross-sectional area ratio = 0·7; aspect ratio = 3.6) to test the effect of geometry on hydrodynamic performance and oxygen transfer behaviour. For otherwise fixed conditions, the design of gas–liquid separators affected the induced liquid circulation rate, the depth of penetration of the bubble layer in the downcomer, the gas holdup in the downcomer, the mixing time and the overall volumetric gas–liquid oxygen transfer coefficient. The gas holdup in the riser was only marginally affected by the design of the separator. The impact of the various separator designs on hydrodynamic behaviour could be explained as emanating from a combination of the gas–liquid separating ability of the design and its hydraulic resistance.     

Synthesis of block copolymers by using polysilanes

Poly(methyl phenyl silane) was used to photoinitiate the polymerization of methyl methacrylate. Poly(methyl methacrylate) (PMMA), obtained this way, contains remaining polysilane chains. Photolysis of this PMMA in the presence of vinyl monomers such as styrene makes it possible to prepare block copolymers. Such PMMA prepolymers were also used to induce the polymerization of cyclohexene oxide through formation of PMMA-attached silyl radicals and subsequent oxidation to the corresponding ions in the presence of N-ethoxy-2-methylpyridinium hexafluorophosphate resulting in the formation of a block copolymer.     

Block Copolymers by Using Combined Controlled Radical and Radical Promoted Cationic Polymerization Methods

Summary A novel synthetic procedure for the preparation of block copolymers based on the combination of diphenylethene (DPE) mediated controlled radical polymerization and radical promoted cationic polymerization is described. In the first step, the controlled polymerization of styrene (St) and methyl methacrylate (MMA) in presence of DPE yields polymers with various structures of diphenylethyl units in the main chain. Upon heating these prepolymers undergo scission to give polymeric radicals. Oxidation of these radicals by onium salts such as diphenyliodonium heaxfluorophosphate (Ph₂I⁺PF₆ ⁻) and N-ethoxy-2-methylpyridinium hexafluorophosphate (EMP⁺PF₆ ⁻) yields reactive cations capable of initiating cationic polymerization of cyclohexene oxide (CHO). Block copolymer structure was confirmed by IR and NMR spectral measurements and GPC analysis. Received: 13 December 2002/Revised version: 25 March 2003/ Accepted: 11 March 2003 Correspondence to Yusuf Yagci     

XRF and Raman Characterization of Antimonite

Abstract

Two type Antimonite (stibnite) ore samples were analyzed by polarized energy dispersive X-ray fluorescence (PEDXRF) spectrometry and by confocal Raman spectrometry (CRS) in this study. The samples were collected from two different localities (?zmir-Ödemi? and Bursa-Uluda? zones from Turkey) according to the sampling methods. The first locality hosted within the metamorphic basement and the second locality hosted within the felsic intrusive rock units. The goal of this paper is to compare two different stibnite samples from various regions through PEDXRF and CRS with the optical characteristic features under the ore microscope. Ore microscopy studies reveal that the ?zmir-Ödemi? stibnite is associated mainly with calcite and the Bursa-Uluda? stibnite is associated with celestite and quartz as gangue minerals. Two different colored species were observed in the stibnite of the studied samples. Ore microscopy results, CRS with the PEDXRF results show that the stibnites from the two different localities have different mineral associations, different chemical compositions, and different physical properties.     

Development of a new multi-criteria optimization method for engineering design problems

In this study, we developed a new multiple criteria optimization method in the context of engineering design. The design of experiment (DoE) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) methods are combined to identify an objective function of the selected problem by fitting a polynomial to the experimental data in a multiple linear regression analysis. Then, the regression function is incorporated into a mathematical model with the criteria constraints to determine an optimal criteria set. The proposed method can be used to compare the functionality and results provided by different scenario analyses of a building design optimization problem, which represent design solutions. We applied the DoE–TOPSIS model to solve different multi-criteria design optimization problems using two examples from the literature and obtained satisfactory results. In the examples, the results obtained using the combined DoE–TOPSIS model are almost in agreement with those derived from conventional multi-criteria design optimization methods, which demonstrates the simplicity, usability, and flexibility of the proposed method in solving engineering design problems.     

SpyDetector: An approach for detecting side-channel attacks at runtime

International Journal of Information Security - In this work, we first present a low-cost, anomaly-based semi-supervised approach, which is instrumental in detecting the presence of ongoing...     

Human gait analysis based on biological motion and evolutionary computing

Human motion has already deeply affected many aspects of psychological and social research. On the other hand, because of the huge challenges and new dimensions of its increasingly extreme applications, this field remains an inspiring area in which to explore rich possibilities in the fields of artificial intelligence and bio-informatics. In this research, we investigated a novel approach to identify individuals based on their gaits. Furthermore, we investigated a new avenue of the research toward the biometric identification of humans that involves the classification of human gait using the power of genetic programming (GP). Moreover, we also propose an approach that applies collaborative filter using multiple evolved classifiers to address the challenges of non-determinism and insufficient generality of GP.     

In Vitro and In Vivo Characterization of Biodegradable Poly(organophosphazenes) for Biomedical Applications

The need and the growing interest in polymers as biomaterials have led to the synthesis of new polymers with a variety of physico-chemical properties. Biomedical application of such materials not only depends on their physical properties but also on biocompatibility and biodegradability. Polyphosphazenes are a family of ‘hybrid inorganic–organic polymers’ with inorganic elements in the backbone and organic side-groups. The polyphosphazenes constitute a family of greatly diverse performance materials with a broad spectrum of properties. The present review focuses on the biodegradable polyphosphazenes, their biocompatibility, and degradation behavior both in vitro and in vivo. This review also covers the use of biodegradable polyphosphazenes as controlled release devices.     

Photochemically masked benzophenone: Photoinitiated free radical polymerization by using benzodioxinone

A new photoinitiating system for free radical polymerization of methyl methacrylate (MMA) is reported. This system consists of benzodioxinone and hydrogen donors such as triethylamine (TEA), N,N-dimethyl ethanol amine (DMEA) and tetrahydrofuran (THF). A feasible mechanism involves photoinduced formation of benzophenone from benzodioxinone and subsequent hydrogen abstraction of photoexcited benzophenone from hydrogen donors to yield radicals capable of initiating polymerization of MMA.