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Esmaeili A Rustaiyan A Nadimi M Larijani K Nadjafi F Tabrizi L Chalabian F Amiri H 《Natural product research》2008,22(6):516-520
The essential oils obtained by hydrodistillation of the leaves, stems and flowers of Salvia reuterana (Lamiaceae) were analysed by GC and GC/MS. Germacrene D and beta-caryophyllene were the major constituents in all the three oils: (28.5, 27.7 and 32.5%) and (15.5, 11.4 and 16.6%), respectively. Bicyclogermacrene (10.2 and 13.2%) was also prodominated in the stem and flower oils. The composition of the oils was mostly quantitativel rather than qualitatively different. All the oils consisted mainly of sesquiterpenes and a small percentage of non-terpenoid compounds. In all the three oils, monoterpenes were in a concentration less than 0.5%. Antibacterial activity was determined by the measurement of growth inhibitory zones. 相似文献
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We study various binomial and monomial ideals arising in the theory of divisors, orientations, and matroids on graphs. We use ideas from potential theory on graphs and from the theory of Delaunay decompositions for lattices to describe their minimal polyhedral cellular free resolutions. We show that the resolutions of all these ideals are closely related and that their \({\mathbb {Z}}\)-graded Betti tables coincide. As corollaries, we give conceptual proofs of conjectures and questions posed by Postnikov and Shapiro, by Manjunath and Sturmfels, and by Perkinson, Perlman, and Wilmes. Various other results related to the theory of chip-firing games on graphs also follow from our general techniques and results. 相似文献
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Izabela Janowska Kambiz Chizari Jean-Hubert Olivier Raymond Ziessel Marc Jacques Ledoux Cuong Pham-Huu 《Comptes Rendus Chimie》2011,14(7-8):663-670
Palladium supported on vertically aligned multi-walled carbon nanotubes (Pd/VA-CNTs) is used as catalyst for the C-C coupling reactions of p-iodonitrobenzene with styrene and ethyl acrylate under microwaves irradiation. Pd/VA-CNTs catalyst exhibits higher activity compared to Pd supported on activated charcoal, under the same reaction conditions. Due to the microwaves irradiation, the kinetics of the reaction is strongly accelerated compared to that obtained with a traditional heating mode. The macroscopic form of aligned CNTs support allows an easy recovery of the catalyst, avoiding a costly post-reaction filtration. In addition, the interaction between the active phase and the support leads to the negligible leaching of palladium during recycling tests. The observed results indicate that Pd/CNTs is a recyclable and stable heterogeneous catalytic system. 相似文献
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The volatile constituents of the essential oil of wild Melissa officinalis L. obtained from the Kurdistan province of Iran were extracted by headspace/solid-phase micro-extraction and were analysed by gas chromatography and gas chromatography/mass spectrometry. Of a total of 14 compounds in the oil, 12 (85.7%) were identified. The main components were as follows: (E)-citral (37.2%), neral (23.9%) and citronellal (20.3%). Some physicochemical properties, such as the logarithm of calculated octanol-water partitioning coefficients (log?K (ow))(,) total biodegradation (TB (d) in mol?h(-1) and g?h(-1)), water solubility (S (w), mg?L(-1) at 25°C) and median lethal concentration 50 (LC(50)), were calculated for compounds 1-14 from M. officinalis L. 相似文献
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Kambiz Abedi 《Optical and Quantum Electronics》2012,44(1-2):55-63
In this paper, asymmetric intra-step-barrier coupled double strained quantum wells structure (AICD-SQW), segmented transmission-line and mushroom-type waveguide that improve the performance of traveling wave electroabsorption modulators (TWEAM) are presented. The AICD-SQW structure shows that electroabsorption modulator properties such as large change in absorption, high extinction ratio, large Stark shift, very low insertion loss, zero chirp, and higher figures of merit are possible to be achieved simultaneously as compared with intra-step quantum well (IQW). The segmented transmission-line method allows us to design a TWEAM with above 25 Ω impedance and very high bandwidth. Furthermore, increasing the width of p-cladding layer with the same active layer to reduce the resistance in p-i-n mushroom-type waveguide of TWEAM based on AICD-SQW improve the microwave propagation loss and thus the high-speed electro-optical response. For this purpose, the transmission-line microwave properties of TWEAM such as microwave index, microwave loss, and characteristic impedance are obtained for active and passive segments of transmission-line. Then equivalent circuit model elements are extracted. The modulation response of segmented transmission-line mushroom-type TWEAM is obtained by HSPICE simulation and compared to circuit model simulation results of conventional mushroom-type TWEAM counterpart. The analysis results indicate that the segmented transmission-line mushroom-type TWEAM can achieve much wider bandwidth than the conventional mushroom-type TWEAM counterpart, with a small penalty in electro-optic conversion gain due to AICD-SQW structure. 相似文献
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Farbod Alimohammadi Mazeyar Parvinzadeh Gashti Ali Shamei Amir Kiumarsi 《Superlattices and Microstructures》2012
Silver was stabilized on multi-walled carbon nanotubes (MWCNTs) by chemical-reduction technique using N,N-dimethylformamide (DMF) as a reducing agent. The influence of silver on the performance of carbon nanotubes (CNTs) was investigated by employing Fourier-transform infrared spectra (FTIR), Raman spectroscopy (RAS), thermal gravimetric analysis (TGA), zeta potential measurement, scanning electron microscope (SEM), electron dispersive X-ray spectrometer (EDX), transmission electron microscopy (TEM), and reflectance spectroscopy (RS). FTIR as well as RS methods evidenced the synthesis procedure using chemical reduction method was successful. Performing TGA of the samples under oxygen atmosphere demonstrated that the silver nanoparticles (Ag NPs) generated on MWCNTs surface can decrease the thermal stability of the particles by the catalytic oxidation of CNTs. In contrary, the thermal stability of the MWCNTs has improved under nitrogen atmosphere. EDX results showed the presence of Ag, Au and Co on the surface of deposited sample. The synthesised silver multi-walled carbon nanotubes (Ag–MWCNTs) were found to have higher UV reflection activity compared with untreated particles. The Ag–CNTs can be used in producing anti-UV composites. 相似文献
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A state space model(SSM) is derived for quantum-dot semiconductor optical amplifiers(QD-SOAs).Rate equations of QD-SOA are formulated in the form of state update equations,where average occupation probabilities along QD-SOA cavity are considered as state variables of the system.Simulations show that SSM calculates QD-SOA's static and dynamic characteristics with high accuracy. 相似文献
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Karl Geisen Kambiz Taraz Herbert Budzikiewicz 《Monatshefte für Chemie / Chemical Monthly》1992,123(1-2):151-178
Summary The structure of four new pyoverdins (Pf12-IA, -IIA, -IB und IIB) isolated from the culture medium ofPseudomonas fluorescens 12 was elucidated by combination of spectroscopic methods and degradation reactions. The pyoverdins comprise (1S)-5-amino-2,3-dihydro-8,9-dihydroxy-1H-pyrimido[1,2-a]quinoline-1-carboxylic acid whose amino group carries a 3-carboxypropanoyl-(IA), succinamoyl- (IIA), 4-carboxy-4-oxobutanoyl- (IB) or L-4-amino-4-carboxybutanoylresidue (II B) and whose carboxyl group is bound amidically to the N-terminus of D-Ser-L-Lys-Gly-. According to the short-hand-nomenclature suggested in [2, 3] the pyoverdins may be described as pyoverdin-Q-sKGOsSGK*oES*-SUC(IA), pyoverdin-Q-sKGOsSGK*o-ES*-SUCA (IIA), pyoverdin-Q-sKGOsSGK*oES*-KGL (IB) and pyoverdin-Q-sKGOsSGK*oES*-GLU (IIB). The pyoverdins described here possess the most complex structure encountered so far as their peptide part comprises eleven amino acids and the cyclo-tetrapeptide substructure. In addition, they are of special interest as for the first time glutamic acid could be identified as a chromophore side chain which is the key compound for the citric acid cycle to which belong all dicarboxylic acids found so far in pyoverdins.
Verwendete Abkürzungen ASK Acylseitenkette - Chr Chromophor1 a - (HO)Chr Chromophor1 b - Dns Dansyl-Rest - DP Dansylpeptid - EDTA Ethylendiamintetraessigsäure - FAB Fast Atom Bombardment (PI=positive Ionen) - (HO)Orn N5-Hydroxyornithin - (CHO, HO)Orn N5-Formyl-N5-hydroxyornithin - PITC Phenylisothiocyanat - RP-HPLC Reversed-Phase High Performance Liquid Chromatography - Kgl -Ketoglutarsäure bzw. 4-Carboxy-4-oxobutanoyl-Rest - R t Retentionszeit - Suc Bernsteinsäure bzw. 3-Carboxypropanoyl-Rest - Suca Succinamoyl-Rest - Suci Succinimido-Rest - TAB Trifluoracetyl-n-butylester - TEA Triethylamin 相似文献
Verwendete Abkürzungen ASK Acylseitenkette - Chr Chromophor1 a - (HO)Chr Chromophor1 b - Dns Dansyl-Rest - DP Dansylpeptid - EDTA Ethylendiamintetraessigsäure - FAB Fast Atom Bombardment (PI=positive Ionen) - (HO)Orn N5-Hydroxyornithin - (CHO, HO)Orn N5-Formyl-N5-hydroxyornithin - PITC Phenylisothiocyanat - RP-HPLC Reversed-Phase High Performance Liquid Chromatography - Kgl -Ketoglutarsäure bzw. 4-Carboxy-4-oxobutanoyl-Rest - R t Retentionszeit - Suc Bernsteinsäure bzw. 3-Carboxypropanoyl-Rest - Suca Succinamoyl-Rest - Suci Succinimido-Rest - TAB Trifluoracetyl-n-butylester - TEA Triethylamin 相似文献