Showing papers by "Zonguldak Karaelmas University published in 2001"

Free radical crosslinking of unsaturated bacterial polyesters obtained from soybean oily acids

Abstract: Poly(-3-hydroxy alkanoate) containing unsaturated side chains, PHA-soybean, were produced by feeding Pseudomonas oleovorans with soybean oily acids obtained from soybean oil. Unsaturation of PHA-soybean were found to be 10 mol-% of unsaturated side chains. Main saturated part of the biopolymer was Poly(3-hydroxy octanoate) with minor hexanoate and decanoate units. PHA films were crosslinked via free radical mechanism by means of thermally or under UV irradiation in the presence of benzoyl peroxide, benzophenon, and /or ethylene glycol dimethacrylate (EGDM). Crosslinking yield of the PHA films were found to be from 81 to 93 wt.-% from the sol-gel analysis. Swelling properties of the crosslinked PHA films in chloroform and toluene were also studied. Mc values of crosslinked PHAs were also calculated using Flory-Rehner equation. The crosslinked biopolyester obtained by thermally at 60 °C with benzoyl peroxide indicated the highest crosslinking density. Glass transition temperatures (Tg) of crosslinked biopolyester samples were changed from −33 to −45 °C while that of PHA-soybean was −60 °C.

Graft Copolymerisation of Methyl Methacrylate onto a Bacterial Polyester Containing Unsaturated Side Chains

Abstract: Poly(3-hydroxy alkanoate) containing unsaturated side chains was produced by feeding Pseudomonas oleovorans with soybean-soil acid (PHA-soybean). The composition of PHA-soyebean were found to be 10 mol-% of unsaturated side chains with the saturated hexanoate, octanoate and decanoate units. Methyl methacrylate (MMA) was thremally grafted on PHA-soybean in the presence of benzoyl peroxide. Fractional precipitation was used to isolate the grapht copolymer from related homopolymers. PHA content in copolymer samples was between 15 to 30 mol-%. Graft copolymer samples were kept in hydroquinone to prevent post polymerization leading to crosslinking in a day under laboratory atmospheric conditions. Copolymer characterization was performed using GPC and NMR techniques. Thermal analysis of the graft copolymer indicated the decomposition and glass transition temperatures of the PHA and PMMA segments of the graft copolymers. They also showed elongation at break in the range 10 to 21 related to the plasticizer effect of the biopolyester segments.

Poly(styrene peroxide) and Poly(methyl methacrylate peroxide) for Grafting on Unsaturated Bacterial Polyesters

Abstract: A new soluble terephthaloyl oligoperoxide (OTP) was synthesized by the reaction of terephthaloyl peroxide and 2,5-dimethyl 2,5-dihydroperoxy hexane. Thermal polymerization of vinyl monomers (styrene, methyl methacrylate) with OTP yielded poly(styrene peroxide) (PS-P) and poly(methyl methacrylate peroxide) (PMMA-P) which are used in the grafting reactions onto medium chain length unsaturated bacterial polyester obtained from soybean oily acids with Pseudomonas oleovorans poly(3-hydroxy alkanoate), (PHA). PS-g-PHA and PMMA-g-PHA graft copolymers isolated from related homopolymers were characterizated by 1H NMR spectrometry, FT-IR spectroscopy, thermal analysis and gel permeation chromatographic (GPC) techniques. Swelling measurement of the crosslinked graft copolymers were also measured to calculate qv values.

The first regio- and diastereoselective synthesis of homochiral perhydroimidazoisoxazoles via the 1,3-dipolar cycloaddition of imidazoline 3-oxides with (1S)-(−)-β-pinene

Abstract: The 1,3-dipolar cycloaddition of imidazoline 3-oxides 1 with (1 S )-(−)-β-pinene proceeds regio- and diastereoselectively to give homochiral perhydroimidazoisoxazole derivatives 3 in high yields in the cases of imidazoline 3-oxides 1a – e but in low yields in the reactions of 1f – g . The preferred attack of (1 S )-(−)-β-pinene to the cyclic nitrone was shown to be anti–endo. The reaction of racemic nitrones (±)- 1f – g with the homochiral β-pinene gave the adduct from the ( S )-nitrone and the corresponding imidazole. The adducts 3 undergo retro-1,3-dipolar cycloaddition when heated in the condensed phase or in diphenyl ether to give the corresponding imidazole and β-pinene.

2,6-Bis­[1-(phenyl­imino)­ethyl]­pyridine

Abstract: The structure of the title compound, C21H19N3 (BIP1), has been determined. The mol­ecule lies on a crystallographic mirror plane. The terminal phenyl groups are rotated 60.2 (2)° from the plane of the ethyl­idene­pyridine system.

A computer aided process planning system for concurrent engineering

Abstract: This paper present ProPlanner, a hybrid computer aided process planning (CAPP) system designed to facilitate concurrent product development. ProPlanner automates information acquisition, product design interpretation, manufacturing operation planning, cutting tool selection, set-up planning and operation sequencing. The system employs a hybrid approach utilizing a combination of rule-based reasoning and object-oriented programming. It enables the early detection of design errors during the design stage before manufacturing and incorporates a feedback mechanism for correcting errors and giving suggestions to modify the product design.

Symptomatic palatal myoclonus: an unusual cause of respiratory difficulty.

Abstract: A 67-year-old man presented with dysphagia and difficulty breathing. Physical examination revealed palatal myoclonus. In this patient, the respiratory difficulty was caused by the fragmentation of breathing. Electromyographic examination of the cricothyroid muscle demonstrated rhythmic myoclonic jerks. Magnetic Resonance Imaging (MRI) yielded a pontine midline and right sided tegmental infarct. The patient responded to sodium valproate.

Studies on the interaction of iron(III) with tetraaza macrocycles

Abstract: Tetraaza macrocycles and their Fe3+ complexes have been prepared and characterized by elemental analysis, i.r., n.m.r., and e.s.–m.s. spectroscopic techniques. The solution behaviour of the macrocycles and their complexes was studied by potentiometric titrations.

On the Stability and Uniqueness of the Solution of the Integral Geometry Problems Along Plane Curves

Abstract: The problems of integral geometry, in the sense that based on the work of Radon [1], consist in determining a function by its given integrals of this function (or the integrals are taken with a certain weight multiplier) over a family of manifolds. In this study, we consider the integral geometry problems (IGP) including a weight function along the family of plane curves of given curvatures. By reducing the problem of integral geometry to an equivalent boundary value problem for a second order partial dierential equation of mixed type and using the method of energy estimates the uniqueness theorems and the stability estimates are given for the linear and the nonlinear problems of integral geometry along some regular family of curves by Mukhometov in [2, 3]. With the choice of the coordinates and the family of the curves, more general than the ones of Mukhometov, as in [4] and by giving a general condition on the curvatures of the curves of the family along which the problem is considered, we prove a stability estimate and the uniqueness of the solution of these problems on the space of suciently smooth functions. Then, these stability and uniqueness results are investigated for the problems along the families of some special plane curves and we present the stability and uniqueness results for IGP with a less general condition on the curvatures, with the curvatures of a special form, along the family of circles with xed radius and along the family of circles of varying radius centered on a xed circle.