Showing papers by "Istanbul Technical University published in 1992"
TL;DR: The diamonds and diamondiferous rocks of Dabie Shan are interpreted to be the products of ultrahigh pressure metamorphism in the und�rthrust basement of the Yangtze continental plate during the early Mesozoic, at greater than 4.0 gigapascals and 900�C.
Abstract: Diamond occurs in ultrahigh pressure metamorphic rocks from Dabie Shan, Anhui Province, eastern China. Diamond-bearing rocks include eclogite, gamet-pyroxenite, and jadeitite. Diamond occurs in a mineral assemblage with coesite and jadeite. The diamonds and diamondiferous rocks of Dabie Shan are interpreted to be the products of ultrahigh pressure metamorphism in the underthrust basement of the Yangtze continental plate during the early Mesozoic, at greater than 4.0 gigapascals and 900°C. This interpretation is based on the distribution of rock units, the stability field of diamond, and isotopic data indicating a crustal origin for the rocks. Most diamonds occur as euhedral inclusions in garnets and are 10 to 60 micrometers across, although some are up to 700 micrometers across.
768 citations
294 citations
TL;DR: In this article, it has been shown that hydrogen peroxide interferes in chemical oxygen demand (COD) analysis, and further shows how to allow for this interference in future COD analysis.
210 citations
TL;DR: In this article, the authors used long-period P-and SH-waveforms to determine the source parameters of the two largest earthquakes of the 1971 May 12 sequence that occurred in the Burdur region.
Abstract: SUMMARY
It is now widely accepted that the rapid extension observed in western Turkey is mainly accommodated by large active normal faults which control the geomorphology. The NE-SW trending Burdur, Acigol and Baklan basins bounded by large faults form a system of half-graben whose orientation is evident in both the topography and the tilting of Neogene sediments adjacent to them.
We used long-period P- and SH-waveforms to determine the source parameters of the two largest earthquakes of the 1971 May 12 sequence that occurred in the Burdur region. The main shock was followed by many aftershocks, which were distributed in a broad zone elongated NE-SW, parallel to the long axes of the basins in the region.
Documented surface breaks of the 1971 event suggest that the northwest-dipping faults along the southern margin of the Burdur Basin are those which moved. Well-exposed fault planes are found dominantly to the south of Burdur lake; the surface dips of these faults are greater than that of the NW-dipping nodal plane obtained for the main shock. Combined seismological and geological observations suggest that these faults have listric geometries.
155 citations
TL;DR: In this paper, the applicability of pyridinium salts, a new class of photoinitiators, of appropriate redox potential Ered1/2 in oxidizing carbon-centered free radicals to carbocations capable of initiating the polymerization of various compounds is demonstrated.
Abstract: General aspects of the photoinitiated free radical promoted cationic polymerization are discussed. The applicability of pyridinium salts, a new class of photoinitiators, of appropriate redox potential Ered1/2 in oxidizing carbon-centered free radicals to carbocations capable of initiating the polymerization of various compounds is demonstrated. Moreover, the use of polysilanes as source for readily oxidizable free radicals is described. Furthermore, possibilities for preparing block copolymers by free radical promoted cationic polymerization are pointed out.
66 citations
TL;DR: In this article, an electrochemical systematic study is realized to determine the kinetic parameters (effect of sweep rate, effect of temperature, order of reaction, etc.), and reaction mechanisms are suggested which take into account these results.
60 citations
TL;DR: In this paper, the effects of casting conditions and deformation processing on the mechanical properties of unreinforced A356 aluminum and A356-20 vol pct SiC composite were investigated by tensile properties in these compounds fabricated by either sand casting or squeeze casting techniques.
Abstract: The effects of casting conditions and deformation processing on the mechanical properties of unreinforced A356 aluminum and A356-20 vol pct SiC composite were investigated by tensile properties in these compounds fabricated by either sand casting or squeeze casting techniques followed by hot working to 33, 50, 90, and 95 percent reductions. The evolution of the microstructure and values of tensile properties were evaluated for the cast materials in each of the hot worked conditions. It was found that, while the deformation processing of the sand-cast composite resulted in banding of the Al and SiC particles within the microstructure, such features were not observed in the squeeze-cast microstructure. The tensile strengths of the squeeze cast materials was found to be higher than those of the sand cast materials, for both the unreinforced and composite samples, while increased amounts of deformation were found to improve the ductility of the composite.
57 citations
TL;DR: The polymerization of acrylamide (AAm) initiated by polyazoesters (PAE) possessing poly(ethylene glycol) (PEG) segments and azo functions was investigated in aqueous solution at 70°C as mentioned in this paper.
Abstract: The polymerization of acrylamide (AAm) initiated by polyazoesters (PAE) possessing poly(ethylene glycol) (PEG) segments and azo functions was investigated in aqueous solution at 70°C. Polymerization of AAm initiated by PAE yields polymers with PEG segments and appropriate hydroxy functions for the subsequent redox polymerization. Polymerization of AAm induced by these polymers in conjunction with Ce(IV) provided increase in the molecular weight of the initial polymer without formation of insoluble polymer. The water-soluble polymers obtained at various stages were tested in the flocculation of suspension of tincal concentrate and showed good flocculating properties.
Die Polymerisation von Acrylamid (AAm) in wasriger Losung, initiiert mit Polyazoestern (PAE) mit Poly(ethylenglykol) (PEG)-Segmenten, wurde bei 70°C untersucht. Die gebildeten Polymeren tragen Hydroxy-Endgruppen, die einer nachfolgenden Redox-Polymerisation mit Ce(IV) zuganglich sind. Bei der mit diesem System initiierten Polymerisation von Acrylamid ergab sich eine Erhohung des Molekulargewichts des vorgelegten polymeren Initiators ohne gleichzeitige Bildung unloslicher Polymerer. Die erhaltenen wasserloslichen Polymeren zeigten gute Flockungseigenschaften bei der Behandlung einer Tinkalkonzentrat-Suspension.
43 citations
TL;DR: In this article, steam was found to be a more effective sweep gas than nitrogen at low velocities in fixed-bed pyrolysis of Goynuk oil shale but, at higher velocity, the differences were considerably less marked.
41 citations
TL;DR: In this paper, the reproducibility of coloration cycles in TiO2 films was investigated as a function of time, and a saturation-like behavior of colour centres produced by charge injection in the form of Li+ ions was found.
40 citations
TL;DR: In this paper, the critical surface tension of wetting (gamma-c) values measured in methanol/water system were used to classify hydrophilic and partially hydrophobic minerals.
TL;DR: In this article, the kinetics of the lipolysis of Nigella sativa oil catalyzed by native lipase in crushed seed were studied between 20 and 90°C, and data fitted the pseudo first-order rate equation at 20, 30 and 40°C; and the pseudo second-order equation at 50, 60 and 70°C.
Abstract: Kinetics of the lipolysis ofNigella sativa oil catalyzed by native lipase in crushed seed were studied between 20 and 90°C. Data fitted the pseudo first-order rate equation at 20, 30 and 40°C; and the pseudo second-order equation at 50, 60 and 70°C, but neither equation fit at 80 and 90°C. Lipolysis approximated first-order with respect to water.
TL;DR: In this article, a pre-concentration sorbent for copper and cadmium was used as an asorbent prior to their determination by flame atomic absorption spectrometry (FAAS).
Abstract: 3-Aminopropyltriethoxysilane, (C2H5O)3 Si(CH2)3NH2, loaded on silica gel was used as a pre-concentration sorbent for copper and cadmium prior to their determination by flame atomic absorption spectrometry (FAAS). Both batch and column methods were used for the separation of the above metals. The analytes are quantitatively retained on the proposed adsorbent at pH 6.5. The complexation capacity of the collector is 0.032 mmol Cu/g silica. In the batch method, the effects of shaking time and the ratio of metal/silica on the retention by the asorbent were investigated. Columns filled with the collector provided quantitative recovery of the above metals from standardized samples as well as from sodium chloride solutions.
TL;DR: In this article, boundary layer equations for second order fluids are derived by using exterior calculus, and the general isovector fields for these equations are found by using interior calculus, from the four independent isovectors only one provides useful solutions which is a scaling transformation.
TL;DR: In this paper, a project to build an electrochromic device in which all active layers could be deposited from gels is reported, where a gel form of polyvinyl butyral was used as a fast ion conductor.
TL;DR: In this paper, the performance characteristics of unsaturated granular media were described using Monod type biological kinetics and mass transfer concepts within microbial films, and the effects of wetted surface area and other parameters on substrate removal were numerically evaluated.
Abstract: The performance characteristics of the unsaturated granular media were described using Monod type biological kinetics and mass transfer concepts within microbial films. For this purpose computer techniques were first developed for the numerical evaluation of the normalized biofilms mathematical model. The effects of wetted surface area and the other parameters on substrate removal were then numerically evaluated. The theory enables one to transfer the experimental findings obtained from a pilot plant to another filter for design purposes. Practical application of the theory to experimental results was also demonstrated.
TL;DR: The pyridinium salt of partially chloromethylated poly(methylphenysilylene) (Q-PMPSi) in aqueous solution is capable of initiating the polymerization of hydrophilic vinyl monomers, e.g. acrylic and methacrylic acid, acrylamide, 2-hydroxyethyl methacrylate and 1-vinyl-2-pyrrolidone.
Abstract: Radicals formed during photoscission of the pyridinium salt of partially chloromethylated poly(methylphenysilylene) (Q-PMPSi) in aqueous solution are capable of initiating the polymerization of hydrophilic vinyl monomers, e.g. acrylic and methacrylic acid, acrylamide, 2-hydroxyethyl methacrylate and 1-vinyl-2-pyrrolidone.
TL;DR: In this paper, a redox polymerization of methylmethacrylate (MMA) using Ce(1V) with poly(oxyethylene) having azo and hydroxy functions was carried out to yield multiblock copolymers with azo linkages in the main chain.
Abstract: SUMMARY Redox polymerization of methylmethacrylate (MMA) using Ce(1V) with poly(oxyethylene) having azo and hydroxy functions was carried out to yield methylmethacrylate-ethylene glycol block copolymers with labile azo linkages in the main chain. These prepolymers were used to initiate the radical polymerization of styrene through the thermal decomposition of the azo group, resulting in the formation of multiblock copolymers. Successful blocking has been confirmed by fractional precipitation, a strong change in the molecular weight distribution and spectral measurements. ZUSAMMENFASSUNG: Durch Ce(1V)-initiierte Redoxpolymerisation von Methylmethacrylat mit Poly(oxyethylen), das Azo- und Hydroxygruppen enthielt, wurden Copolymere mit labilen Azogruppen in der Hauptkette erhalten. Diese Prepolymeren wurden zur durch thermischen Zerfall der Azogruppen initiierten radikalischen Polymerisation von Styrol eingesetzt, wobei Multiblockcopolymere entstanden, was durch fraktionierte Filllung, Anderung der Molekulargewichtsverteilung und spektroskopische Messungen nachgewiesen wurde.
TL;DR: Ce(IV) salt-malonic acid or citric acid initiator systems were used for the polymerization of acrylamide in the presence of electrolysis as discussed by the authors, and the highest polymerization yield was obtained with a stainless-steel electrode.
Abstract: Ce(IV) salt-malonic acid or citric acid initiator systems were used for the polymerization of acrylamide in the presence of electrolysis. This allowed Ce(III) to be converted to Ce(IV) during polymerization. Graphite, silver, chromium/nickel, lead, platinum and stainless-steel electrodes were used. The highest polymerization yield was obtained with a stainless-steel electrode.
Acrylamid wurde in wasiger Losung mit den Initiatorsystemen Ce(1V)-Malonsaure bzw. Citronensaure unter Elektrolysebedingungen polymerisiert, was die elektrolytische Umwandlung von Ce(III) zu Ce(IV) wahrend der Polymerisation ermoglicht. Graphit-, Silber-, Chrom-Nickel-, Blei-, Platin- und Edelstahl-Elektroden wurden verwendet. Der groste Polymerisationsumsatz wurde mit der Edelstahlelektrode erreicht.
TL;DR: In this paper, a simulation model is provided for the determination of the shading effect of the surrounding buildings on a building in a settlement, and the simulation of shaded areas on vertical surfaces of buildings, created by neighbouring buildings, used the shadow components of a vertical pole on a three-dimensional coordinate system.
TL;DR: In this article, the authors evaluated the biological treatability of textile wastewaters generated by the knit and wowen fabric finishing category with specific emphasis on the assessment of different residual COD components.
TL;DR: In this article, the second order equations of steady motion for second order fluids are expressed in a special coordinate system generated by the potential flow corresponding to an inviscid fluid and boundary conditions are derived from the equations of motion by employing a technique of matched asymptotic expansion.
TL;DR: In this paper, the authors reported work carried out to process 2 million tons of copper slag for recovery of cobalt and copper in the northern part of Turkey from ancient time.
Abstract: An approximate amount of 2 million tons of copper slag has been lying on the northern part of Turkey from ancient time. This slag contains 0.43% cobalt and 1% copper. This paper reports work carried out to process this slag for recovery of cobalt and copper.
TL;DR: It is concluded that the new structure approximates the maximum entropy more closely compared to the three-parameter structure and leads to a more reliable and better modelling of AR data fields.
TL;DR: In this article, the free vibrations of a stiffened shallow shell numerically by the collocation method within the frame of the theory of thin orthotropic shallow shells were analyzed for various geometrical and material parameters.
Abstract: Introduction S plates and shells have found wide applications in aircraft, spacecraft, and ships. Hence, the dynamic characteristics of stiffened plates' and shells" have been studied extensively. The purpose of the present work is to analyze the free vibrations of a stiffened shallow shell numerically by the collocation method within the frame of the theory of classical thin orthotropic shallow shells. The eccentricity of stiffeners is included through the moments of inertia of the stiff eners. The vibration characteristics of unidirectionally and orthogonally stiffened shallow shells are studied for various geometrical and material parameters.
TL;DR: In this paper, the 2-vinyl pyridine/styrene (2VP/St) copolymer in terms of molecular weight and molar ratio was investigated, and the disperse dyeability of these fibers were investigated.
Abstract: Polypropylene fibers containing various amounts and different types of 2-vinyl pyridine/styrene (2VP/St) copolymer in terms of molecular weight and molar ratio were prepared, and the disperse dyeability of these fibers were investigated. In addition, the disperse dyeability of 2VP/St copolymer alone was also studied. © 1992 John Wiley & Sons, Inc.
TL;DR: In this article, design criteria for nitrification and denitrification of high-strength nitrogenous wastes have been derived by pilot-scale experiments in two submerged filters in series and Molasses proved to be a suitable carbon source in denitrif ication.
TL;DR: In this article, a quasi-living radical polymerization of styrene (St) and methyl methacrylate (MMA) was carried out in the presence of tri phenylmethyl mercaptan (TPMM) as a chain transfer agent to give trityl terminated polymers.
Abstract: Radical polymerizations of styrene (St) and methyl methacrylate (MMA) were carried out in the presence of tri phenylmethyl mercaptan (TPMM) as a chain transfer agent to give trityl (triphenylmethyl) terminated polymers. Transfer constants were found to be 17.8 and 0.71 for St and MMA, respectively. Trityl terminated polymers served as thermal “INITERS” for polymerization of vinyl monomers which proceeded via a quasi-living radical mechanism. This procedure makes it possible to prepare block copolymers. © John Wiley & Sons, Inc.
TL;DR: In this paper, the Laplace-transformed KB equation for the lifetime distribution was used to interpret these dimensions in terms of a crossover in the thread-like PEHMA network in PVA c particles.