Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

TÜBİTAK

Discipline
Keyword
Publication Year
Publication

Articles 11191 - 11220 of 12081

Full-Text Articles in Entire DC Network

Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye Jan 2000

Antiferromagnetic Transition In \Alpha-Mn-Fe System, R. K. Nkum, F. Boakye

Turkish Journal of Physics

Antiferromagnetic transition in $\alpha$-Mn-Fe alloys has been studied using resistivity-temperature measurements from 300 to 1.5 K. The results indicate that the transition temperature $T_N$ of the samples studied increases with increasing Fe concentration. This suggests that the N\'{e}el temperature is affected by Fe. Also, Fe plays a significant role in the local disorder on the magnetic moment of the ions in the complex manganese structure.


Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan Jan 2000

Radioluminescent Properties Of Cds(Ag) Crystals, Ruhi̇ Kaplan, F. Esen Özsan

Turkish Journal of Physics

The radioluminescent proporties of silver-doped cadmium sulphide, CdS(Ag), crystals excited by 5.5 MeV $ \alpha $-particles from an $ ^{241}$Am radioactive source have been investigated. The emission spectra, decay profiles and thermal quenching curves were obtained accurately at temperatures between 80 K and 300 K. Two main radioluminescent emission bands centered at about 5760 \AA\ and 5940 \AA\ were observed. Their decay curves were found to be fast and nonexponential. From the thermal quenching of radioluminescence, the activation energies of centers responsible for these emissions were determined. The results are interpreted as the radioluminescence is possibly due to donor-acceptor pair …


Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab Jan 2000

Synthesis And Characteristics Of Nickel Manganite By Lithiation, S. V. Salvi, M. R. Parab

Turkish Journal of Physics

Spinel nickel manganite has been synthesized using ceramic technique, from (2MnO$_{2}$+NiO) mixture reduced using LiAlH$_{4}$. Powder X-ray diffractometry (XRD) indicates the formation of cubic spinel (a=8.33 A^o), while IR absorption spectral features are rather broad, though similar to those of spinel. The d.c. electrical conductivity of the ceramic is much smaller than that reported for NiMn$_{2}$O$_{4}$. Even though the band gap remains the same, when the sintering temperature is increased from 950^oC to 1100 ^oC, all other changes are insignificant except that the porosity and particle size nearly halve. The characteristics of the system are discussed in terms of `lithiation'.


Barrier Heights Of Antimony / And Bismuth / P -Silcon (100) Junctions, A. A. Oberafo, A. Z. Ziriki Jan 2000

Barrier Heights Of Antimony / And Bismuth / P -Silcon (100) Junctions, A. A. Oberafo, A. Z. Ziriki

Turkish Journal of Physics

Junctions were fabricated in vacuum of about $10^{-5}$ Torr by thermal evaporation of Sb or Bi onto chemically etched $p$-type silicon (100) substrates. The electrical properties were studied by current voltage (I-V) measurements. Some of the Sb and Bi junctions were heated-treated for $\frac{1}{2}$ hr at 200 and 150^oC, respectively. The barrier height (BH) was equal to 0.64 eV for both as-deposited and heat-treated Sb junctions, while it was 0.56 and 0.74 eV for as-deposited and heat-treated Bi Junctions, respectively. These observatimons indicate that for Sb junctions, annealing at a temperature of 200^oC resulted only in partial elimination of any …


Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik Jan 2000

Determination Of Optical Constant Of Materials By Two Different Methods: An Application To Single Crystals Si, Hazi̇ret Durmuş, Haluk Şafak, Haldun Karabiyik

Turkish Journal of Physics

The normal reflectance of single crystal Si was measured at 0.5 ­5.6 eV range by unpolarized light. Optical parameters of Si were determined from this reflectance data by using two different methods: oscillator fit procedure and Kramers-Kronig analysis. The refractive index, extinction coefficient and the real and imaginary parts of complex dielectric constant obtained by these two methods were compared. A good agreement was found between two methods. Furthermore, the optical parameters so obtained seem to be in a satisfactory agreement with the literature.


Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak Jan 2000

Crystallographic Analysis Of Martensitic Transformation In Cusn Alloy, Ekrem Artunç, Seyfetti̇n Çakmak, Seval Çakmak

Turkish Journal of Physics

In this study, the Kajiwara model has been applied to Cu-14.8at.\%Sn alloy with good agreement with experimental results. For this alloy, the austenite phase has a body centered cubic (bcc) lattice and the martensite phase has a monoclinic 9R superlattice. Using the lattice parameters of both phases, the calculated habit plane indices, magnitude of the lattice invariant shear and orientation relationships, have been compared with the observed results for this alloy.


A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten Jan 2000

A Product Operator Formalism Of 3d J-Resolved Nmr Spectroscopy For Is_Nk_M(I = 1/2, S = 1/2, K = 1/2) Spin System, Özden Tezel, Azmi̇ Gençten

Turkish Journal of Physics

Product operator formalism is widely used for analytical description of multiple-pulse NMR experiments for weakly coupled spin systems. 3D J-resolved NMR spectroscopy is widely used in order to resolve the chemical shift along one axis and spin-spin coupling parameters along the two other axis. In this study, product operator theory is used for analytical description of heteronuclear 3D J-resolved NMR spectroscopy for the \( IS_nK_m (I=1/2, S=1/2, K=1/2; n=1,2, m=1,2,3) \) spin system.


Cover And Contents Jan 2000

Cover And Contents

Turkish Journal of Zoology

No abstract provided.


Taxonomic And Paelogeographic Approaches To The Dasyclad Algae In The Upper Jurassic (Kimmeridgian)-Upper Cretaceous (Cenomanian) Peritidal Carbonates Of The Fele (Yassıbel) Area (Western Taurides, Turkey), İsmai̇l Ömer Yilmaz Jan 1999

Taxonomic And Paelogeographic Approaches To The Dasyclad Algae In The Upper Jurassic (Kimmeridgian)-Upper Cretaceous (Cenomanian) Peritidal Carbonates Of The Fele (Yassıbel) Area (Western Taurides, Turkey), İsmai̇l Ömer Yilmaz

Turkish Journal of Earth Sciences

In the Fele (Yassıbel) area in the north of Beyşehir Lake in the Western Taurides, Upper Jurassic (Kimmeridgian) - Upper Cretaceous (Cenomanian) peritidal carbonates were studied in detail. In this study, 30 species of dasyclad algae were identified and 3 new Salpingoporella species were identified within the peritidal carbonates. It was determined that they belong to 13 different genera: Acroporella, Actinoporella, Campbelliella, Clypeina, Cylindroporella, Epimastopora, Epimastoporella, Kopetdagaria, Macroporella, Otternstella, Rajkaella, Salpingoporella, and Selliporella. Salpingoporella is the dominant genus. Some of the species are new records for Turkey: Clypeina nigra, Clypeina parasolkani, Otternstella lemmensis, Salpingoporella biokovensis, Salpingoporella circassa, Salpingoporella piriniae, and …


Clinopyroxene Compositions Of The Isotropic Gabbros From The Sarıkaraman Ophiolite: New Evidence On Supra-Subduction Zone Type Magma Genesis In Central Anatolia, Kenan M. Yaliniz, M. Cemal Göncüoğlu Jan 1999

Clinopyroxene Compositions Of The Isotropic Gabbros From The Sarıkaraman Ophiolite: New Evidence On Supra-Subduction Zone Type Magma Genesis In Central Anatolia, Kenan M. Yaliniz, M. Cemal Göncüoğlu

Turkish Journal of Earth Sciences

The Sarıkaraman Ophiolite is one of the least dismembered ophiolitic units of the allochthonous Central Anatolian Ophiolites, which retains its recognizable pseudostratigraphy. The Sarıkaraman Ophiolite is represented in its lowermost part by isotropic gabbros. Within the isotropic gabbro sequence, clinopyroxenes are observed as small, colorless relicts with a cloudy appearance. In most of the samples, they are completely replaced by a successive generation of green to brown amphiboles. Clinopyroxenes display diopsitic to augitic compositions within the range of En 45 Fs 5 Wo 49 to En 50 Fs 9 Wo 41 . They are Ca-rich and Na-poor (Na 2 O


Field, Petrographic And Geochemical Features Of The Baranadağ Quartz Monzonite Of The Central Anatolian Granitoids, Turkey, Nurdan S. Aydin, A. Piril Önen Jan 1999

Field, Petrographic And Geochemical Features Of The Baranadağ Quartz Monzonite Of The Central Anatolian Granitoids, Turkey, Nurdan S. Aydin, A. Piril Önen

Turkish Journal of Earth Sciences

The Baranadağ quartz monzonite is one of the granitioid intrusions of the Central Anatolian Crystalline Complex (CACC) which represents the passive continental margin of the Anatolide-Tauride platform. Medium to coarse-grained Baranadağ quartz monzonites typically include mafic microgranular enclaves and K-feldspar megacrysts and are cut by aplitic dykes representing the youngest magmatic activity of the study area. The intrusion is mainly composed of orthoclase, plagioclase, quartz, hornblende, biotite and clinopyroxene. It displays a slightly alkaline character and relatively well-developed calc-alkaline trend. The metaluminous Baranadağ quartz monzonites show comparable field, petrographic and/or geochemical features with those of the H-type (Hybrid) granitoids of …


Biostratigraphic And Environmental Analysis Of The Upper Jurassic- Lower Cretaceous Carbonate Sequence In The Başoba Yayla Area (Trabzon, Ne Turkey), Kemal Tasli, Erol Özer, Cemi̇l Yilmaz Jan 1999

Biostratigraphic And Environmental Analysis Of The Upper Jurassic- Lower Cretaceous Carbonate Sequence In The Başoba Yayla Area (Trabzon, Ne Turkey), Kemal Tasli, Erol Özer, Cemi̇l Yilmaz

Turkish Journal of Earth Sciences

In the Başoba Yayla (Trabzon, NE Turkey) area, which is located in the Eastern Pontides northern zone, platform carbonates were deposited during the Late Jurassic-Early Cretaceous time in environments varying from intertidal/ supratidal to outer shelf. The carbonate sequence begins with a thick dolomite unit of the Late Jurassic to Early Cretaceous age. The following unit is rich in benthic foraminifers and pelecypoda shells. The foraminiferal assemblage comprising Vercorsella laurentii/camposaurii and Pseudolituonella gavonensis indicates a Late Hauterivian to Early Aptian age for this unit. The Late Aptian-Albian facies is characterized by bioclastic wackestones containing benthic foraminifers typical of outer platform …


Deformation Of Stibnites And Pyrites In The Madsan Antimony Deposit (Niğde, Turkey): Implications For Pressure-Temperatureconditions Of Local Deformation, İlkay Kuşcu, Ayhan Erler Jan 1999

Deformation Of Stibnites And Pyrites In The Madsan Antimony Deposit (Niğde, Turkey): Implications For Pressure-Temperatureconditions Of Local Deformation, İlkay Kuşcu, Ayhan Erler

Turkish Journal of Earth Sciences

The Madsan antimony deposit at the southeastern part of the Niğde province (south-central Turkey) includes a series of epithermal veins hosted by marbles and gneisses. The veins have a simple mineralogy of quartz, calcite, stibnite and pyrite as major constituents, and cinnabar occurs in trace amounts. The deposit experienced a progressive deformation evidenced by a set of textures developed especially in stibnite and pyrite. These are pressure lamellae and annealing as the main textures, and curvature, off-set of pressure lamellae and fracture filling as the textures of minor importance. These were developed in three successive deformation phases. Pressure lamellae represent …


Mafic Microgranular Enclaves In The Kozak Granodiorite, Western Anatolia, Cüneyt Akal, Cahi̇t Helvaci Jan 1999

Mafic Microgranular Enclaves In The Kozak Granodiorite, Western Anatolia, Cüneyt Akal, Cahi̇t Helvaci

Turkish Journal of Earth Sciences

Enclaves which are relicts of initial basic magma give important information on the origin and evolution of granitic magmas. The mafic microgranular enclaves from the l-type Kozak pluton are less than 1 m that are located at the margin of pluton and mostly less than 15 cm and are generally in sharp contact with the surrounding granodiorite. In some cases, several enclaves may occur close to each other, but they are not closely clustered to form swarms. Most of the enclaves are ellipsoidal in shape. The largest enclaves are less ellipsoidal with curved boundaries. The mafic microgranular enclaves contain same …


Rock-Forming Nannofossils In Uppermost Jurassic-Lowercretaceous Rock Units Of Northwest Anatolia: Nannoconusand Its Resived Taxonomy, Sevi̇nç Özkan Altiner Jan 1999

Rock-Forming Nannofossils In Uppermost Jurassic-Lowercretaceous Rock Units Of Northwest Anatolia: Nannoconusand Its Resived Taxonomy, Sevi̇nç Özkan Altiner

Turkish Journal of Earth Sciences

Nannoconids have been recorded in a rock-forming quantity in the uppermost Jurassic-Lower Cretaceous rock units in Northwest Anatolia, Turkey. Samples were collected from seventeen stratigraphic sections spanning the calciturbidities of the Yosunlukbayiri Formation and pelagic micrites of the Sogukçam Limestone. Because of rareness and difficulties for extracting of calcareous nannofossil species particularly zone markers in these type lithologies, nannoconids have particular attention in terms of biostratigraphy. Twenty nine species of nannoconids were recorded in the studied samples. Their taxonomy were revised and their stratigraphic ranges were given. The classification of genus Nannoconusis based on the gross morphology of the test, …


Geology Of The Dereiçi (Şavsat, Artvin) Cu-Pb-Zn Deposits, Mesut Soylu, Ayhan Erler Jan 1999

Geology Of The Dereiçi (Şavsat, Artvin) Cu-Pb-Zn Deposits, Mesut Soylu, Ayhan Erler

Turkish Journal of Earth Sciences

The geological relationships between the rock units in the Dereiçi/Şavsat (Artvin) region and vein-type Cu-Pb-Zn deposits were presented in this paper. The study area comprises the Upper Cretaceous intermediate volcanic rocks and sedimentary rocks, with Post-Eocene dykes of andesitic and diabasic composition. The mineral deposits are classified as (1) Sphalerite-Galena-Chalcopyrite-Pyrite veins (Talatin Madeni, Binektasi and Fikrinin Madeni), (2) milky quartz-Chalcopyrite-Sphalerite-Galena-Pyrite veins and (3) Chalcopyrite-Pyrite veins. The general paragenetic sequence of the mineralizations is observed as quartz I-pyrite-chalcopyrite-sphalerite-galena-quartz II-chalcocite-covellite. The wall rocks are subjected to silicification, sericitic alteration, chloritization and carbonatization.


Along-Strike Discontinuity Of Active Normal Faults And Its Influence On Quaternary Travertine Deposition; Examples From Western Turkey, Zi̇yadi̇n Çakir Jan 1999

Along-Strike Discontinuity Of Active Normal Faults And Its Influence On Quaternary Travertine Deposition; Examples From Western Turkey, Zi̇yadi̇n Çakir

Turkish Journal of Earth Sciences

Detail mapping of active fault zones bounding four travertine masses in the Gediz and Menderes grabens of western Turkey revealed that they are divided into geometric fault segments up to 13 km long. Fissures, supplying the carbonate-rich waters that give rise to the travertines are preferentially developed at the ends of the fault segments or in extensional step-over zones where the offset between the fault strands is about 1 km or more. The deposition of travertines in such structural settings is probably a consequence of the network of fissures supplying the carbonate-rich waters being highly interconnected where extensional strains were …


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Biology

No abstract provided.


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Biology

No abstract provided.


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Biology

No abstract provided.


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Biology

No abstract provided.


The Extended Hybrid Model For Optical Phonon Confinement, C. R. Bennett, B. K. Ridley, N. A. Zakhleniuk, M. Babiker Jan 1999

The Extended Hybrid Model For Optical Phonon Confinement, C. R. Bennett, B. K. Ridley, N. A. Zakhleniuk, M. Babiker

Turkish Journal of Physics

The theory of optical phonons and their confinement in heterostructures is reviewed with analogies made to the theory of acoustic phonons. The dielectric continuum (DC) model is obtained when bulk dispersion is ignored and the hybrid model is found when dispersion is included. The issue of boundary conditions is investigated and the solutions are shown with comparisons made using electron-phonon scattering.


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Earth Sciences

No abstract provided.


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Earth Sciences

No abstract provided.


A Research On Evaluating For Recreation And Tourism Potential Of Natural Resource Values At Çoruh Watershed Area (Yusufeli Region), Öner Demi̇rel Jan 1999

A Research On Evaluating For Recreation And Tourism Potential Of Natural Resource Values At Çoruh Watershed Area (Yusufeli Region), Öner Demi̇rel

Turkish Journal of Agriculture and Forestry

The watershed area of Çoruh River in Yusufeli Region with its untouched landscape values is one of the distinguished potential areas where recreational and nature tourism activities can be carried out. In this research, the natural and cultural potentials of the area have been studied. In addition, recreational and touristic areas as well as the general recreational tendencies of people in the study area have been determined. A total of 500 questionnaire forms, which were prepared in the light the data gathered from this preliminary research, were applied to people living in the research area at both residential and temporary …


Cover And Contents Jan 1999

Cover And Contents

Turkish Journal of Veterinary & Animal Sciences

No abstract provided.


Rapd Analysis Of Genetic Variation In Barley, Gülruh Albayrak, Nermi̇n Gözükirmizi Jan 1999

Rapd Analysis Of Genetic Variation In Barley, Gülruh Albayrak, Nermi̇n Gözükirmizi

Turkish Journal of Agriculture and Forestry

The variation between wild barley lines ( Hordeum murinum, Hordeum bulbosumand Hordeum vulgare spontaneum) orig-inated from Turkey were investigated comparatively at the molecular level with the Random Amplified Polymorphic DNA (RAPD) technique. Leaf DNAs extracted from different barley lines were amplified with randomly chosen primers in a Polymerase Chain Reaction (PCR). Rates of polymorphisms between the 23 lines were determined in pairwise comparisons. The lowest value of poly-morphism was determined to be 0.3% between wild barley lines numbered 50327 and 50354, and between 48101 and 50365 while the highest polymorphism value was determined to be 60% between wild barley lines …


Leaf Area Prediction Models ( Uzçelik-I) For Different Horticultural Plants, Sezgi̇n Uzun, Hüseyi̇n Çeli̇k Jan 1999

Leaf Area Prediction Models ( Uzçelik-I) For Different Horticultural Plants, Sezgi̇n Uzun, Hüseyi̇n Çeli̇k

Turkish Journal of Agriculture and Forestry

A total of 343 leaves were selected randomly from fifteen different horticultural plants, that are widely grown under Samsun ecological conditions. Lamina width, length and leaf area were measured. The plants were divided into three groups according to lamina shape, plants with similar shapes being put into the same group for developing an equation to predict their leaf areas. The first group of plants included avocado species [1], lotus plum used as persimmon rootstock [2], 52 ÜN 13 selected persimmon type [3], Hayward kiwifruit cultivar [4], Bonica F1 aubergine [5] and Yalova F1 pepper [6]. The second group included GAP …


Planning Of Allowable Cut In Working Forest Groups Of Calabrian Pine For Timber Production, Altay Uğur Gül Jan 1999

Planning Of Allowable Cut In Working Forest Groups Of Calabrian Pine For Timber Production, Altay Uğur Gül

Turkish Journal of Agriculture and Forestry

Linear programming models were developed and solved according to different interest rates and rotation periods for the planning of allowable cut using data obtained from working forest groups of calabrian pine in the Gazipaşa Forest Enterprise in Antalya. Then, the most suitable rotation period; regeneration and afforestation area; total and annual allowable cut; and present net value were determined.


Evaluation Of The Greenhouse Tomato Growth Model Tomgro Under Çukurova Protected Cultivation Conditions, Sevi̇lay Topçu, A. Nafi̇ Baytorun Jan 1999

Evaluation Of The Greenhouse Tomato Growth Model Tomgro Under Çukurova Protected Cultivation Conditions, Sevi̇lay Topçu, A. Nafi̇ Baytorun

Turkish Journal of Agriculture and Forestry

In recent years, models of the greenhouse environment and of crops have been used to determine optimal strategies for environment control in regions where new greenhouse industries are developing. In this study, the tomato crop growth model TOMGRO, which was developed to describe the growth and yield of an indeterminate tomato variety under controlled conditions of greenhouse cultivation in Israel, was evaluated under Çukurova conditions. The input parameters for the model were observed from a greenhouse experiment conducted during 1995-1996 growing season. There was good agreement between the simulated and observed number of nodes. The simulated number of leaves and …