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Bulunan: 55 Adet 0.001 sn
Koleksiyon [16]
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Yazar [20]
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Sage oil extraction and optimization by response surface methodology

Akalin M.K. | Tekin K. | Akyüz M. | Karagöz S.

Article | 2015 | Industrial Crops and Products76 , pp.829 - 835

Sage oil extraction is important as most of the components in sage play an important role in the treatment of various diseases. The aim of the present study was to optimize supercritical extraction parameters for sage (Salvia officinalis L.) oil yield by response surface methodology. A 3-factor Box-Behnken design was used to generate factor combinations. The optimal conditions for the sage oil extraction yield were 280. °C extraction temperature, 110. min extraction time and 11% (wt/v) plant concentration in ethanol. The validation experiment showed that the actual and predicted values were 49.21 and 47.04. wt%, respectively. The co . . .mposition of sage essential oil consisted mainly of acid esters together with phenols, limonene, indoles, and pyrroles. These compounds can be used in various industrial applications. © 2015 Elsevier B.V Daha fazlası Daha az

Open and closed circuit dry grinding of cement mill rejects in a pilot scale vertical stirred mill

Pilevneli C.C. | Kizgut S. | Toroglu I. | Çuhadaroglu D. | Yigit E.

Article | 2004 | Powder Technology139 ( 2 ) , pp.165 - 174

In this study, separator rejects of a closed circuit cement tube milling were dry ground in a 10-l pilot scale vertical stirred mill. Tests were done as open and closed circuit. The results were evaluated by size distributions, Blaine surface area of the products and the specific energy consumed during the tests. Mill capacity and the stirring speeds were the investigated parameters for the open circuit tests, whereas closed circuit tests were carried out at a constant stirring speed but variable discharge rate. Five speed levels used in the open circuit grinding tests are 200, 400, 600, 800 and 1000 rpm. The capacities were determi . . .ned to obtain product Blaine surface areas in the limits between 2000 and 5000 cm2/g. Closed circuit tests have resulted in 87%, 182% and 452% circulating loads. © 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az

A Simple Traction Assembly for Shoulder Arthroscopy in Lateral Decubitus Position: A Cost-Effective Alternative

Songur M. | Sahin E.

Article | 2015 | Arthroscopy Techniques4 ( 4 ) , pp.165 - 174

The lateral decubitus position shoulder arthroscopy requires traction for positioning, as well as distraction. We describe a cost-effective lateral decubitus traction assembly for shoulder arthroscopy. © 2015 Arthroscopy Association of North America.

Resistance fluctuations in amorphous Cr74Fe26 films

Öner Y. | Kilic A. | Özdemir M. | Senoussi S.

Article | 1998 | Journal of Magnetism and Magnetic Materials185 ( 3 ) , pp.305 - 308

Magnetoresistance measurements ??/? have been carried out on an amorphous Cr74Fe26 film in the temperature range of 4-120 K in a magnetic field up to 120 kOe. We observed that the isotropic component of the magnetoresitance at low temperatures first decreases with increasing field due to the decrease in the spin fluctuations (negative magnetoresistance), goes through a minimum at a certain field value, Hc and then starts to increase (positive magnetoresistance) as the magnetic field is further increased. As the temperature increases, Hc shifts to a higher field and the magnetoresistance on both sides of this field (negative and posi . . .tive magnetoresistance) decreases. The magnetoresistance becomes almost zero at temperatures between 10-16 K. However, as the temperature is further increased, the magnetoresistance starts to increase again. This overall behaviour with the resistivity data have been interpreted successfully in terms of localization effects. We have also observed huge oscillations in the resistivity at low frequencies (7-70 mHz) in the temperature range where ??/? becomes weaker. Starting with the temperature at about T = 15 K, the amplitudes of these oscillations reduce with both increasing and decreasing temperatures. However, the frequencies of these oscillations increase with decreasing temperature. No detectable oscillation in the resistivity has been observed at temperatures below T = 8 K and above T > Tc (the Curie temperature, Tc = 43.8 K). We have no full explanation for this phenomenon, however, it is tempting to ascribe it to some kind of spin density wave. © 1998 Elsevier Science B.V. All rights reserved Daha fazlası Daha az

Testicular development, ultrasonographic and histological appearance of the testis in ram lambs immunized against recombinant LHRH fusion proteins

Ülker H. | Kanter M. | Gökdal Ö. | Aygün T. | Karakuş F. | Sakarya M.E. | DeAvila D.M.

Article | 2005 | Animal Reproduction Science86 ( 03.Apr ) , pp.205 - 219

Sixteen native ram lambs weaned at 10 wk of age were divided into two groups. Eight animals were immunized against LHRH with a mixture of two fusion proteins: ovalbumin-LHRH-7 and thioredoxin-LHRH-7. The immunized lambs received a primary immunization plus two booster immunizations at 4 and 12 wks. Animals in the control group (n = 8) were not treated. Scrotal measurements and blood samples were taken at 2-week intervals. Beginning at 25 wk of age, semen was collected and sexual behaviour was evaluated on a weekly basis. At 35 and 37 wk of age testes and accessory glands of all animals were subjected to ultrasound scanning. At 37 wk . . . of age animals were slaughtered and testes were evaluated histologically. Serum LHRH antibodies (P < 0.01) were detected in animals of the immunized group which had reduced serum testosterone concentrations (P < 0.01). Testicular development was suppressed in the immunized animals (P < 0.01). Immunized animals exhibited mounting activity 5 wks later than control animals. No mature spermatozoa containing ejaculates were collected from immunized animals. Control animals had moderately echogenic ultrasonographic appearance at 37 wk age, whereas immunized animals had hypoechogenic images. Mean seminiferous tubule diameter in immunized lambs was significantly smaller than that in control lambs. Basal membrane was thickened and hyalinized; there was an increase in peritubular connective tissue. No proliferating spermatogonia or mature spermatozoa were present in the tubules in these animals. There were no differences in the ultrasonographic appearance of prostate and vesicular gland between control and immunized animals. The LHRH recombinant fusion proteins were effective in immunological castration in ram lambs when started at 10 wk of age as noted by differences in serum testosterone, testicular histology and ultrasonographic appearance of testis and weight of accessory sex glands. Determining the effects of immunization on ultrasonographic appearance of the testis related to time after immunization requires further investigations. © 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az

Novel ruthenium(II)-N-heterocyclic carbene complexes; Synthesis, characterization and catalytic application

Yaşar S. | Karaca E.Ö. | Şahin Ç. | Özdemir I. | Şahin O. | Büyükgüngör O.

Article | 2015 | Journal of Organometallic Chemistry789-790 , pp.1 - 7

The synthesis of highly active ruthenium(II) catalyst based on N-heterocyclic carbene (NHC) bearing alkyl and aryl groups is reported. The complexes are easily handled in very good yields via synthesis of silver-NHC complexes and subsequent reaction with [RuCl2(p-cymene)]2 in dichloromethane (DCM) under N2 condition. All new compounds were characterized by LC-MSMS, elemental analysis, NMR spectroscopy and X-ray diffraction. With the development of a more efficient catalytic system for transfer hydrogenation of aryl ketones and aldehydes in mind, the catalytic performance of the Ru-NHC complexes for transfer hydrogenation was investi . . .gated. © 2015 Elsevier B.V. All rights reserved Daha fazlası Daha az

Residual stresses and white layer in electric discharge machining (EDM)

Ekmekci B.

Article | 2007 | Applied Surface Science253 ( 23 ) , pp.9234 - 9240

The effect of dielectric liquid and electrode type on white layer structure in electric discharge machined surfaces has been studied in terms of retained austenite and residual stresses using X-ray diffraction method. The machining tests were conducted by using two different tool electrodes (copper and graphite) and dielectric liquid (kerosene and de-ionized water) under same operational conditions. The present work suggests that the surface is saturated with carbon irrespective of the tool electrode material when machining with kerosene dielectric liquid. But, retained austenite is formed on the surface due to carbon uptake from gr . . .aphite tool electrode when machining with de-ionized water dielectric liquid. On the other hand, even though surface residual stresses increase with structural non-homogeneities in the white layer, no clear consequences have been observed in residual stress distribution beneath the white layer. © 2007 Elsevier B.V. All rights reserved Daha fazlası Daha az

Modeling of unburned carbon in fly ash and importance of size parameters

Bilen M. | Kizgut S.

Article | 2016 | Fuel Processing Technology143 , pp.7 - 17

Unburned carbon (UBC) percentage in coal ash can be considered as an economic and environmental constraint since it is not only an important characteristic in terms of combustion efficiency but also it becomes more of an issue of further utilization of ash. In this study, particle size distribution (PSD) effect on UBC in fly ash (FA) was discussed and efficient size parameter of PSD in terms of UBC formation was determined. At the first stage of the study, regarding ash formation, percentage of any set of coal particles which are more likely to form fly ash (FA) was theoretically determined. For this purpose, a formulation including . . . the size parameters was proposed. Secondly, with the help of a 3-day long systematical control of power, the effect of size distribution on UBC was obtained. The size distributions of these samples showed that an increase in D32 size parameter causes an increase in the amount of UBC as well. Relationships between the amount of UBC and mean values of size parameters (D10, D50, D90, D32, D43)were all statisticallymeaningful for both units of power plant concerned but D32 size parameter has a better fit among all the size parameters. In summary, D32 & UBC have a regression coefficient of 0.90 (R2 ~ 0.9),while other size parameters (D10, D50, D90, D43) & UBC have regression coefficients of 0.2 (R2 ~ 0.2) for both units. Finally, a model including these size parameters was proposed to predict UBC in FA. The model proposed was in good agreement with the measured UBC in FA. © 2015 Elsevier B.V Daha fazlası Daha az

Synthesis, characterization and the Suzuki-Miyaura coupling reactions of N-heterocyclic carbene-Pd(II)-pyridine (PEPPSI) complexes

Yaşar S. | Şahin Ç. | Arslan M. | Ozdemir I.

Article | 2015 | Journal of Organometallic Chemistry776 , pp.107 - 112

N-heterocyclic carbenes (NHCs) are a significant and powerful class of ligands for transition metals. A new series of air and moisture-stable NHC-PdCl2-pyridine complexes, (2a-f), have been described. With the development of a more efficient catalytic system for the cross-coupling of aryl halides in mind, the catalytic performance of the NHC-PdCl2-pyridine complexes for Suzuki cross-coupling under mild conditions in aqueous N,N-dimethylformamide (DMF) was investigated. Electron-rich and electron-poor aryl chlorides were facilely coupled with boronic acids by NHC-PdCl2-pyridine complexes. ©2014 Elsevier B.V. All rights reserved.

Ion-pair extraction and GC-MS determination of linear alkylbenzene sulphonates in aqueous environmental samples

Akyüz M.

Article | 2007 | Talanta71 ( 1 ) , pp.471 - 478

A GC-MS method was developed for the determination of linear alkylbenzene sulphonates (LAS) and sulphophenylcarboxylic acids (SPC) in aqueous environmental samples. LAS and SPC were isolated from aqueous samples using methylene green (MG) as ion-pair reagent and derivatised with diazomethane for their chromatographic analysis. LAS and SPC were then analysed with GC-MS in EI mode as their methyl esters. The method eliminates positive and negative interferences found by the methylene blue method and considered to be selective and sensitive for the determination of LAS and SPC in aqueous samples. The recovery of LAS was 98% with a rela . . .tive standard deviation (R.S.D.) of 2.0% and the detection limit obtained from calculations by using GC-MS results based on S/N:3 was lower than 10 ppb. Obtained results revealed that the method can also be employed in the analysis of organic compounds bearing sulphate and sulphonate groups. © 2006 Elsevier B.V. All rights reserved Daha fazlası Daha az

Effects of acceptor phase and donor phase properties on sodium ions transport from aqueous solutions using liquid membrane systems

Altın, Süreyya | Demircioğlu, Nuhi | Peker, İbrahim | Altın, Ahmet

Article | 2007 | Colloids and Surfaces A: Physicochemical and Engineering Aspects306 ( 1-3 SPEC. ISS. ) , pp.14 - 21

In this study, the effects of the acceptor phase and the donor phase properties on sodium ion transport were examined in bulk liquid membrane systems. In the experiments, toluene and a mixture of toluene-dichloromethane (90-10%, v/v) containing 1 × 10-3 M DB18C6 (dibenzo18crown6) was used as the membrane. In order to examine the effects of different the acceptor phases, firstly H2SO4, HCl, HNO3, CH3COOH and distilled water were used as the acceptor phases. Furthermore, the experiments were performed by using various acid concentrations such as 2, 0.2 and 0.02 M of acids, as the acceptor phase. In the second part of the study, the ef . . .fect of donor phase on sodium ion transport was examined. For this examination, Na2SO4, NaNO3, NaOH and NaCl were applied. In order to determine the effect of the donor phase concentration, the experimentation was performed using 1.08 × 10-2, 2.17 × 10-2, 3.26 × 10-2 and 4.34 × 10-2 M concentrations of Na+ in form of NaCl. Finally, nonsteady-state kinetics was applied on all data obtained from the experiments and reaction constants (k1, k2, and k3) and the values of the Rmax, tmax, k1/k2 were calculated. Consequently, it was determined that the type and the concentration of the acceptor phase and the donor phase solutions were significant for transport efficiency in liquid membrane systems. The most efficient transport was obtained by applying 2 M H2SO4 and 2.17 × 10-2 M Na+ in form of NaCl. Besides, It was observed that there was a significant effect of the anion attached to the cation on transport efficiency. © 2007 Elsevier B.V. All rights reserved Daha fazlası Daha az

Synthesis and characterization of water soluble O-carboxymethyl chitosan Schiff bases and Cu(II) complexes

Baran T. | Menteş A. | Arslan H.

Article | 2015 | International Journal of Biological Macromolecules72 , pp.94 - 103

In this study, mono-imine was synthesized (3a and 4a) via a condensation reaction between 2,4-pentadion and aminobenzoic acid (meta or para) in alcohol (1:1). The second-imine (CS-3a and CS-4a) was obtained as a result of the reaction of the free oxo groups of mono-imine (3a and 4a) with the amino groups on the chitosan (CS). Their structures were characterized with FTIR and 13C CP-MAS. Then, the water soluble forms of CS-3a and CS-4a were obtained through oxidation of the hydroxide groups on the chitosan to carboxymethyl groups using monochloracetic acid ([O-CMCS-3a]·2H2O and [O-CMCS-4a]·2H2O). Thus, the solubility problem of chito . . .san in an aqueous media was overcome and Cu(II) complexes could be synthesized more easily. Characterization of the synthesized O-carboxymethyl chitosan Schiff base derivatives and their metal complexes, [O-CMCS-3a-Cu(OAc)2]·2H2O and [O-CMCS-4a-Cu(OAc)2]·2H2O, was conducted using FTIR, UV-Vis, TG/DTA, XRD, SEM, elemental analysis, conductivities and magnetic susceptibility measurements. © 2014 Elsevier B.V Daha fazlası Daha az

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