Composition of the essential oils of Angelica sylvestris L. var. sylvestris isolated from the fruits by different isolation techniques

Baser, K. Husnu Can/0000-0003-2710-0231; Ozek, Temel/0000-0003-4251-8783WOS: 000259509300007The essential oils of the fruits of Angelica sylvestris L.var.sylvestris (Umbelliferae) obtained using hydrodistillation (HD), nucrodistillation (MD) and micro-steam distillation-solid-phase microextraction (MSD-SPME) techniques were analyzed by GC and GUMS. The composition of the oils depended on the isolation method employed. alpha-Pinene (25.6%,36.2% and 9.2%, respectively), beta-phellandrene (9.1%, 9.9% and 3.2%), bornyl acetate (7.3%,4.3% and 6.9%), limonene (5.6%, 4.3% and 2.1%). myrcene (4.4%, 4.0% and 1.3%), camphene (3.9%, 4.7% and 1.2%), alpha-chamigrene (3.4%,4.4% and 9.1%) and beta-sesquiphellandrene (2.5%,3.8% and 8.7%) were found as the main constituents in the oils. p-Cresol (6.5%), epi-alpha-bisabolol (5.6%), (Z)-beta-farnesene (5.5%), naphthalene (4.4%), daucene (3.1%), amorpha-4,11-diene (3.1%) and gamma-muurolene (2.5%) were also among the main constituents of the oil isolated by MSD-SPME

The role of optical feedback for controlling chaotic cases in semiconductor laser diodes

In this study the effect of optical feedback in semiconductor laser diodes (LD) has been examined using small signal analysis. The transfer function of LD is given as H(j omega(m))(D) and transfer function of external cavity LD is given as TF(j omega(m))(HD) respectively. The investigated parameters of these transfer functions are external cavity length ( L-ext ), line-width enhancement factor (alpha) and mirror power reflection coefficient (R). The gain change occurring due to optical feedback noise is shown by broadening the bandwidth and narrowing the frequency spectra and the state of chaos (coherence collapse) is determined in each case. By varying the level of reflected optical feedback power ( f(ext) ) the optical feedback system of LD has been improved. In addition to that the system is driven out of chaos by finding reasonable levels for these variables

Different approach for distortion analysis of external cavity laser diode using volterra series

In this study, external cavity laser diode has been modelled and non-linear equations of system are being solved by using Volterra series. In the study, linearized laser diodes rate equations are reorganized for external cavity and these equations are solved with harmonic input method using Volterra series. The transfer functions brought about for harmonics are obtained using Volterra-Weiner series approach. The stability analysis of system is compared from output to input using these transfer functions. Nyquist stability criteria have been used in the analysis

Static and dynamic behaviour of the three cavity semiconductor laser diodes and oscillation frequency shift suppression

In this study, static and dynamic behaviour of a three cavity laser diode model have been analyzed and oscillation frequency shift under the dynamic structure is explanied theoretically. In the analysis, the effect of both the laser facet and the external cavity reflectivities as well as the lengths on the threshold conditions are investigated theoretically. The results have shown that when the optical feedback is increased depending upon the phase of the reflected field, the threshold gain of the laser is decreased The results indicate that strong optical feedback, AR coating of the laser facet and large external cavity lenghts are effective for the frequency shift suppression

The effect of optical confinement factor and gain constant on the distortion levels in InGaAsP semiconductor laser diodes

The effect of optical confinement factor and gain constant (optical gain coefficient) on harmonic distortion in 1,55 mu m. semiconductor laser diodes are investigated by using a mathematical model based on multi-mode rate equations. The model can be extended and used to simulate the output of any direct modulated Fabry-Perot semiconductor laser in long wavelength by changing some of the parameters. Gain and spontaneous emission are included as spectrums, since each mode experiences different gain and spontaneous emission coupled to each mode is different. The important parameters such as Auger recombination, nonradiative recombination, spontaneous emission life time and gain saturation are included in the model. The second harmonic distortion levels are examined and computed graphically for different threshold levels

Design of Quad-Band Bandpass Filter Using Nested Dual-Mode Square Loop Resonators

44th European Microwave Conference (EuMC) -- OCT 05-10, 2014 -- Rome, ITALYWOS: 000392912200236In this letter, design of a quad-band microstrip bandpass filter is presented by using nested placed four dual-mode square loop resonators (DMSLR) having different electrical lengths. Arms of the square loop resonators (SLR) are formed with low/high impedance parts, in order to obtain a maximum miniaturization by nesting DMSLRs and perturbation effects by changing the lengths of low impedance parts for the excitation of degenerate modes. Thus, the proposed configuration allows the control of mode frequencies, bandwidths and transmission zeros for each passband individually. Resonators are coupled to input/output (I/O) ports by feedlines having open-circuited stubs which suppress the harmonics. A dual-mode quad-band bandpass filter has been designed with an electrical length of 0.25 lambda(g) x 0.25 lambda(g) and fabricated, where lambda(g) is the guided wavelength at 1.79 GHz (the lowest resonance frequency). Measured and simulated results are in a good agreement.APS, European Microwave Assoc, IEEE MTT S, horizon houseScientific and Technological Research Council of Turkey (TUBITAK) [112E041]This work was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) under Grant 112E041

A Novel Compact Quad-Band Microstrip Bandstop Filter Design Using Open-Circuited Stubs

IEEE MTT-S International Microwave Symposium Digest (IMS) -- JUN 02-07, 2013 -- Seattle, WAWOS: 000369754300155A novel compact quad-band microstrip bandstop filter design is presented. Input and output ports of the filter are connected with a high impedance transmission line. Proposed filter is designed by using open-circuited stubs attached to the input and output ports. Thus, based on the f(r) - 3f(r) harmonic property of the stub-loaded resonators, four stopbands at 1.15-2.22, 2.94-4.56, 4.95-6.98 and 8.26-8.96 GHz are obtained. Insertion losses of all stopbands are better than 15 dB inside the stopbands. Under the even and odd mode excitations, resonance conditions of the structure are also investigated. For the experimental verification of the simulated results, proposed filter has been fabricated. Simulated and measured results are in a good agreement.IEE MTT