bluuebunny/crossref_metadata_2025_split huggingface dataset:
The synthesis of novel polycyclic heterocyclic ring systems via photocyclization. 8. [1]Benzothieno[2,3‐c]naphtho[1,2‐h]quinoline and [1]benzothieno[2,3‐c]naphtho[1,2‐h][1,2,4]triazolo[4,3‐a]quinoline
Authors: Sasaki Kenji , Castle Raymond N. 
Published: March 2009

AbstractThe previously unknown polycyclic heterocyclic ring systems, namely, [1]benzothieno[2,3‐c]naphtho[1,2‐h]‐quinoline and [1]benzothieno[2,3‐c]naphtho[1,2‐h][1,2,4]triazolo[4,3‐a]quinoline were synthesized via photocyclization of 3‐chloro‐N‐(1′‐phenanthryl)benzo[b]thiophene‐2‐carboxamide.
Selective N‐methylation of ethyl esters of 3‐(1H‐imidazol‐4‐yl)‐2‐propenoic acid
Authors: Mawlawi H. , Monje M. C. , Lattes A. , Rivère M. 
Published: March 2009

AbstractMethods of selective methylation of the nitrogen atoms of the ethyl ester of 3‐(1H‐imidazol‐4‐yl)‐2‐propenoic acid are reported. The nitrogen atom α to the ethylenic chain was methylated after protection of the β nitrogen with a phenacyl group.
Orientation effects in the nitration of the dithieno[b,d]pyridine N‐oxides. Its dependence on acidity of the reaction medium
Authors: Gronowitz Salo , Szabó Kálmán J. , Olugbade Tiwalade A. 
Published: March 2009

AbstractThe nitration of three dithienopyridine‐N‐oxides was investigated. The regiochemistry of the reaction was dependent on the reaction conditions used. Under strongly acidic conditions the positional preference is similar for the N‐oxides and free bases. However, under mildly acidic or neutral conditions a completely different substitution pattern was obtained. In the latter case those ring positions were substituted which are expected to be unfavored or forbidden in electrophilic substitution of the free bases. The structures of the nitro derivatives were proven by extensive use of 1H and 13C nmr spectroscopy.
Indole alkaloids from the roots of an african plant securidaca longipedunculata. I. Isolation by column chromatography and preliminary structural characterization by mass spectrometry
Authors: Costa Carlo , Bertazzo Antonella , Allegri Graziella , Curcuruto Ornella , Traldi Pietro 
Published: March 2009

AbstractThe extraction and the isolation of some alkaloids from the roots of an African plant (Securidaca Longipedunculata Fres) are reported. The structural characterization was performed by mass spectrometry. Alternative ionization methods (FAB and EI), collisionally‐induced decomposition experiments and accurate mass measurements revealed the presence of elymoclavine and dehydroelymoclavine and the presence of a new ergoline alkaloid.
A new type of deoxygenation of quinoxaline N‐oxides
Authors: Kurasawa Yoshihisa , Katoh Ritsuko , Kureyama Tomomi , Yoshishiba Noriko , Takada Atsushi , Kim Ho Sik , Okamoto Yoshihisa 
Published: March 2009

AbstractThe reaction of 6‐chloro‐2‐[2‐(p‐chlorobenzylidene)‐1‐methylhydrazino]quinoxaline 4‐oxide 3a or 2‐[2‐(p‐bromobenzylidene)‐1‐methylhydrazino]‐6‐chloroquinoxaline 4‐oxide 3b with dimethyl acetylenedicarboxylate under reflux in N,N‐dimethylformamide resulted in deoxygenation to give 6‐chloro‐2‐[2‐(p‐chlorobenzylidene)‐1‐methylhydrazino]quinoxaline 4a or 2‐[2‐(p‐bromobenzilidene)‐1‐methylhydrazino]‐6‐chloroquinoxaline 4b, respectively, while the reaction of compound 3a or 3b with dimethyl acetylenedicarboxylate under reflux in dioxane precipitated dimethyl 8‐chloro‐4‐[2‐(p‐chlorobenzyli‐dene)‐1‐methylhydrazino]‐3aH‐isoxazolo[2,3‐a]quinoxaline‐2,3‐dicarboxylate 6a or dimethyl 4‐[2‐(p‐bromobenzylidene)‐1‐methylhydrazino]‐8‐chloro‐3aH‐isoxazolo[2,3‐a]quinoxaline‐2,3‐dicarboxylate 6b, respectively. Further refluxing of compound 6a or 6b in N,N‐dimethylformamide provided compound 4a or 4b, respectively.
Studies in organic mass spectrometry. Part 15 [1]. Electron ionization mass spectra of some 5‐nitro‐3‐thiophenecarboxanilides
Authors: Ceraulo Leopoldo , De Maria Paolo , Fontana Antonella , Frascari Sara , Spinelli Domenico 
Published: March 2009

AbstractThe study of the electron ionization mass spectra of 5‐nitro‐3‐thiophenecarboxanilides 1‐24 has shown peculiar effects induced by the 5‐nitro group on the fragmentation of molecular ions M and the thenoyl cation a (Scheme 1). A comparison of the abundances of the important fragment ions for 5‐nitro‐3‐thiophene‐carboxanilides with those of the corresponding 3‐thiophenecarboxanilides shows that the extent of C‐N amide bond cleavage decreases in the former series as a consequence of the increased bond strength. The produced ion a does not eliminate carbon monoxide as 2‐ and 3‐thenoyl cations usually do. Again this behaviour depends on the electronic effects of the nitro group which strongly destabilizes the 5‐nitro‐3‐thienyl cation and consequently strengthens the carbon‐3 carbonyl carbon bond. Recalling the behavior of the previously studied 2‐ and 3‐thiophenecarboxanilides most of the 2′‐substituted 5‐nitro‐3‐thiophenecarboxanilides give loss of the ‘ortho’ substituent of the phenyl ring furnishing the cyclic ion g(Scheme 2). In the instance of 2′‐alkyl substituted derivatives the formation of abundant ions h' by loss of 5‐nitrothenoyl radical from M (Scheme 3) was observed, thus confirming the occurrence of a cryptic ‘ortho’ effect. The results are also discussed in relation to those obtained on some related benzoylanilides.
Prognostic effect of pathologic fracture in localized osteosarcoma: A cohort/case controlled study at a single institute
Authors: Kim Min S. , Lee Soo‐Yong , Lee Tae R. , Cho Wan H. , Song Won S. , Cho Sang H. , Lee Jun A. , Yoo Ji Y. , Jung Sung T. , Jeon Dae‐Geun 
Published: March 2009

AbstractBackgroundThe negative prognostic role of pathologic fracture in osteosarcoma is not determined, as previous case–control and retrospective cohort studies have produced contradictory results.MethodsWe conducted both cohort (n = 384) and case–control (n = 111) studies on 37 pathologically fractured localized osteosarcoma of extremity.ResultsIn cohort study, patients with a fracture showed a tendency of poorer survival, but the difference did not reach the level of significance (5‐year metastasis‐free survival rates; 48% for cases vs. 61% for controls; P = 0.06). A case–control study on 37 fractured and 74 control recruited from 347 patients matched for tumor size and location showed no survival difference between the cases and controls (P = 0.12).ConclusionsReported negative prognostic effect of a pathologic fracture is likely to be due to confounding by tumor size and location. The present study suggests that the presence of a pathologic fracture has no prognostic relevance. J. Surg. Oncol. 2009;100:233–239. © 2009 Wiley‐Liss, Inc.
Performance comparison between two commercial EM softwares using higher order and piecewise RWG basis functions
Authors: Zhao X. W. , Liang C. H. 
Published: March 2009

AbstractIn this article, numerical result obtained using two different commercially available electromagnetic (EM) codes based on an integral equation method are presented. One of the methods solves the integral equation by the method of moments (MoM) using higher order basis functions (the commercially available parallel software named TIDES), and the other one solves the integral equation by MoM with a multilevel fast multipole algorithm (MLFMA) incorporating the RWG basis functions (the commercially available software FEKO). Numerical results indicate that the integral equation solver with higher order basis functions occupies less than 40% of the RAM and the execution time is significantly less when compared with that of using the RWG basis functions along with MLFMA. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1219–1225, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24271
High order bandpass filter using the first negative resonant mode of composite right/left‐handed transmission line
Authors: Lee Joo‐Young , Kim Dong‐Jin , Lee Jeong‐Hae 
Published: March 2009

AbstractIn this article, a high order composite right/left‐handed (CRLH) bandpass filter using the first negative resonant mode is presented. The proposed filter employs mushroom structure as CRLH transmission line. To design a high order CRLH filter, the design equations are derived by adopting the design equations of the conventional right‐handed (RH) bandpass filter because the resonant property of the first negative mode is similar to that of the first positive mode. The size of a CRLH filter is reduced by 41% when compared with that of conventional RH filter. The measured results are in good agreement with that of full wave simulation. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1182–1185, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24273
Microwave directional filters using metamaterial closed‐loop resonators
Authors: Lobato‐Morales H. , Corona‐Chavez A. , Rodriguez‐Asomoza J. 
Published: March 2009

AbstractThe design and construction of two Metamaterial (MTM) directional filters (DF) for multiplexing applications at 900 MHz is presented. The four‐port filters are realized using composite‐right‐left‐handed (CRLH) closed‐loop resonators, which present small dimensions and suppression of harmonic resonances due to the zeroth‐order resonance produced by MTM's. The first filter uses two conventional transmission lines (TL) between resonators to generate the necessary constructive‐destructive interference for directional behavior. The second design is further miniaturized by a CRLH TL. The simulated responses are compared with measured data showing good agreement. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1155–1156, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24275
SCM transmission in MM fiber with automatic selection of the subcarrier frequency
Authors: Kowalczyk Marcin , Siuzdak Jerzy 
Published: March 2009

AbstractDemonstrated was a 10 Mbit/s binary frequency shift keying subcarrier multiplexing system operating beyond the pass‐band of 1 km MM graded index optical fiber. The system automatically adjusted the carrier frequency to the fiber frequency response. Transmission of four 10 Mbit/s channels was also shown over the same fiber. No visible channel interaction was observed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1212–1214, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24277
Small printed CPW‐fed triangular monopole antenna for ultra‐wideband applications
Authors: Choi Sung Tae , Hamaguchi Kiyoshi , Kohno Ryuji 
Published: March 2009

AbstractA novel small size coplanar waveguide (CPW)‐fed monopole antenna with wide bandwidth and small group delay variation is proposed for ultra‐wideband (UWB) applications. It consists of a triangular patch with a pair of wide stubs on the lower sides thereof and linearly tapered coplanar ground planes. The measured return loss of the fabricated antenna is better than −10 dB from 2.9 to 13.2 GHz. The radiation pattern is nearly omni‐directional and the variation of the measured group delay between two proposed antennas is less than 0.94 ns over the entire UWB band. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1180–1182, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24278
Slow‐wave characteristics of a 1D EBG structure for a miniaturized monopole antenna
Authors: Kim S. H. , Oh K. H. , Lim H. , Song J. I. , Jang J. H. 
Published: March 2009

AbstractTransmission line and monopole antenna embedded with one‐dimensional electromagnetic bandgap (1D EBG) structure were designed, fabricated, and characterized. The slow wave characteristics of a 1D EBG cell were verified using an electro‐optic near‐field mapping system. The group velocity of the electric pulse propagating along the coplanar waveguides loaded with the 1D EBG cell was effectively slowed down compared with that of the pulse propagating along the normal coplanar waveguide without a 1D EBG cell. The slow wave characteristics were utilized to reduce the size of the monopole antenna. A compact monopole antenna could be designed by incorporating a 1D EBG cell on the radiator of the antenna. The fabricated 1D EBG monopole antenna exhibited a 58% reduction in size and performance that was comparable to a large reference monopole antenna. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1231–1235, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24284
Bandpass filter modeling employing Lorentzian distribution
Authors: Al Ahmad Mahmoud , Papaioannou George , Plana Robert , Russer Peter 
Published: March 2009

AbstractThis letter takes a close outlook of modeling a bandpass filter performance with the Lorentzian distribution function. Lorentzian function parameters are correlated with the filter parameters, namely, its bandwidth and center frequency. The zeros and poles of the filter are extracted from the closed form expression of the Lorentzian function, which is used to construct the rational model of the filter. This procedure is expected to optimize the overall filter performance and to construct a consistent equivalent circuit from its computed poles and zeros. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1167–1169, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24288
Improvement of compactness of low pass and band pass filter using a simple combination of cross‐defected ground structure and a discontinuous microstrip line
Authors: Boutejdar Ahmed , Omar Abbas 
Published: March 2009

AbstractThis article presents a method to reduce the size of LPF/BPF using defected ground structure (DGS). The DGS filter structure employs two cross‐slots etched in the ground plane. To validate the feasibility of the proposed design method, a low‐pass filter with 0.1‐dB ripple is designed, fabricated, and measured. Then a simple technique to transform the designed BPF to a LPF was presented. Additionally, a new suspended Layer's technique will be used with DGS in order to reduce more the size and to suppress the second harmonic in reject band. The second order band pass filter was designed using the proposed technique and their simulation results confirmed the validity of the technique. Simulated and measured results of the proposed filters are presented and show good agreements. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1191–1195, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24291
Compact wideband tag antenna for UHF RFID
Authors: Lim Sang Ho , Oh Young Cheol , Lim Ho , Myung Noh Hoon 
Published: March 2009

AbstractA UHF radio frequency identification tag antenna using an inductively coupled feeding method and meander lines is proposed. The antenna has a compact size (diameter: 0.08λ, 26.4 mm), wide bandwidth, and simple matching technique between a tag antenna and a tag chip. To get a physical operation of the proposed antenna, a simplified structure is presented and analyzed. An equivalent circuit model with a simplified structure has good results compared with a simulation. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1291–1294, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24295
Effect of the conductive coating thickness on performance of the microstrip reflectarray
Authors: Abbosh Amin M. 
Published: March 2009

AbstractEffect of thickness of the conductive coating on performance of the microstrip reflectarray is investigated. The unit cell used in this article is in the form of a cross shaped ring. Dimensions of the utilized cell are chosen such that it resonates at the X‐band. The simulated and measured results show that increasing thickness of the conductive layer decreases the losses significantly, reduces the phase slope and shifts the resonant frequency to a higher value, while it has a negligible effect on the phase range. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1288–1290, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24296
Multi‐soliton generation using a micro ring resonator system for DWDM based soliton communication
Authors: Pornsuwancharoen N. , Dunmeekaew U. , Yupapin P. P. 
Published: March 2009

AbstractWe propose a new optical system that can be used to form the multi soliton pulses within the micro ring resonators. The system consists of two micro ring resonators and an add/drop multiplexer that can be integrated into a single system. The large bandwidth signal is generated by using a soliton pulse propagating in a Kerr type nonlinear medium. The tuned soliton pulses in either spatial or temporal modes are obtained by using the add/drop multiplexer. Results obtained have shown that the multi soliton pulses can be localized coherently within the micro ring waveguide. This is shown that the generation of the multi soliton pulses within the micro ring resonator is achieved, which is available for long distance communication with dense wavelength division multiplexing (DWDM). A significant increase in channel number and spacing is obtained, and the large free spectrum range (FSR) of 600 pm is achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1374–1377, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24299
Compact low‐power 2.4 GHz QPSK modulator in CMOS
Authors: El‐Gabaly Ahmed M. , Saavedra Carlos E. 
Published: March 2009

AbstractA compact low‐power QPSK modulator is proposed for short‐range wireless communications using a new pass‐transistor logic circuit. It is experimentally demonstrated in the unlicensed 2.4 GHz ISM frequency band using standard 0.18 μm CMOS technology, with the data rates well exceeding 100 Mbps. The core circuit occupies only 505 μm by 435 μm and consumes less than 19 mW from 1.8 V. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1344–1348, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24300
Slow wave‐modified low profile planar spiral antenna on EBG
Authors: B. A Sapna , Rao Patnam Hanumantha 
Published: March 2009

AbstractA two arm Archimedean spiral antenna is modified to form various slow wave structures that have much lower operating frequency than the conventional spirals, making them compact elements for wideband array applications. Uni‐directional patterns are obtained from a slow wave modified circular star spiral with electromagnetic band gap (EBG) structure. Measured return loss of circular star spiral at 2 GHz backed by perfect electric conductor at λ/4 is −16.37 dB and this is improved to −20.25 dB when the antenna is placed over an EBG at a separation of λ/10. The radiation pattern of antenna on EBG provides a back lobe suppression of 30 dB over an isolated planar modified spiral antenna. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1270–1274, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24303
Characterization and modeling of stacked MIM on‐chip capacitors with high‐capacitance density up to 20 GHz frequency region
Authors: Moon Hyunwon , Yu Sunil , Song Seong‐Sik , Nam Ilku 
Published: March 2009

AbstractIn this article, double‐stacked and triple‐stacked metal‐insulator‐metal (MIM) capacitors fabricated in 0.18 μm CMOS process are reported. These provide high‐capacitance density of 2 fF/μm2 and 3.2 fF/μm2 and excellent dc and RF characteristics, respectively. The lumped circuit model of the stacked MIM capacitors is presented for high‐frequency applications up to 20 GHz. The stacked MIM capacitors offer a reduced chip area for a given capacitance value and are expected to be a viable choice for integration of RF/mixed‐mode circuits in a single chip. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1235–1238, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24305
An equilateral‐triangular microstrip antenna with polarization diversity
Authors: Sung Yongje 
Published: March 2009

AbstractAn equilateral‐triangular microstrip antenna with reconfigurable polarization capability is proposed. The proposed design is achieved by loading with three L‐type slits in the triangular patch and three PIN diodes are utilized to switch the slits on or off. According to the states of the diodes, the reconfigurable antenna can produce linear polarization or right hand circular polarization. An antenna prototype is implemented and measured. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1372–1374, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24306
Macro PZT MEMS based wide‐tunable coupled line resonator
Authors: Al Ahmad Mahmoud , Soulimane S. , Plana R. , van der Linden K. , Riedel M. 
Published: March 2009

AbstractResonators are core components in building advanced radio frequency circuits and systems. Tunable resonators are highly needed for adaptive/tunable microwave components including filters and low‐noise power amplifiers, which are of great potential for the use in future multi‐band multi‐carrier systems. This letter reports a wide tunable two‐coupled microstrip resonator. One of the lines is replaced by a macro MEMS piezoelectric actuator. When bias is applied, the coupling between the two lines is tuned; as a consequence, the center frequency is shifted. This work also takes a close look of the actuator's mechanical resonance. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1336–1338, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24308
The compact quad‐band PCB embedded antenna for mobile handset applications
Authors: Park Gyubok , Hwang Soonho , Park Sungkoo , Byun Joonho , Kim Austin S. 
Published: March 2009

AbstractA novel compact PCB printed quad‐band antenna using a composite loop and PIFA structure for mobile phones is presented. The proposed antenna is composed of a meandered loop antenna and PIFA having the merits of the loop antenna and PIFA. The antenna element is printed on the top ungrounded portion (34.5 mm (W) × 17 mm (L)) of a 0.8‐mm thick FR4 substrate of a mobile phone PCB. Despite the low volume and low profile of the antenna structure, it can fulfill the bandwidth requirements of the GSM900, DCS1800, PCS1900, and UMTS2100 systems with sufficiently high efficiency, thus making it a promising antenna candidate for future mobile terminals. The antenna design was carried out using a high‐frequency structure simulator (HFSS) by Ansoft, and the modeling structure of the mobile handsets was obtained with the aid of the commercially available simulation software SEMCAD. The overall radiation pattern is suitable for mobile applications. To demonstrate the proposed design, simulated and measured results are presented and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1332–1336, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24309